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DNAJA2 and Hero11 mediate similar conformational extension and aggregation suppression of TDP-43 [REPORT]

Many RNA-binding proteins (RBPs) contain low-complexity domains (LCDs) with prion-like compositions. These long intrinsically disordered regions regulate their solubility, contributing to their physiological roles in RNA processing and organization. However, this also makes these RBPs prone to pathological misfolding and aggregation that are characteristic of neurodegenerative diseases. For example, TAR DNA-binding protein 43 (TDP-43) forms pathological aggregates associated with amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). While molecular chaperones are well-known suppressors of these aberrant events, we recently reported that highly disordered, hydrophilic, and charged heat-resistant obscure (Hero) proteins may have similar effects. Specifically, Hero proteins can maintain the activity of other proteins from denaturing conditions in vitro, while their overexpression can suppress cellular aggregation and toxicity associated with aggregation-prone proteins. However, it is unclear how these protective effects are achieved. Here, we used single-molecule FRET to monitor the conformations of the aggregation-prone prion-like LCD of TDP-43. While we observed high conformational heterogeneity in wild-type LCD, the ALS-associated mutation A315T promoted collapsed conformations. In contrast, an Hsp40 chaperone, DNAJA2, and a Hero protein, Hero11, stabilized extended states of the LCD, consistent with their ability to suppress the aggregation of TDP-43. Our results link single-molecule effects on conformation to macro effects on bulk aggregation, where a Hero protein, like a chaperone, can maintain the conformational integrity of a client protein to prevent its aggregation.




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Characterization and Prediction of Organic Anion Transporting Polypeptide 1B Activity in Prostate Cancer Patients on Abiraterone Acetate Using Endogenous Biomarker Coproporphyrin I [Articles]

Organic anion transporting polypeptide (OATP) 1B1 and OATP1B3 are important hepatic transporters. We previously identified OATP1B3 being critically implicated in the disposition of abiraterone. We aimed to further investigate the effects of abiraterone on the activities of OATP1B1 and OATP1B3 utilizing a validated endogenous biomarker coproporphyrin I (CP-I). We used OATP1B-transfected cells to characterize the inhibitory potential of abiraterone against OATP1B-mediated uptake of CP-I. Inhibition constant (Ki) was incorporated into our physiologically based pharmacokinetic (PBPK) modeling to simulate the systemic exposures of CP-I among cancer populations receiving either our model-informed 500 mg or clinically approved 1000 mg abiraterone acetate (AA) dosage. Simulated data were compared with clinical CP-I concentrations determined among our nine metastatic prostate cancer patients receiving 500 mg AA treatment. Abiraterone inhibited OATP1B3-mediated, but not OATP1B1-mediated, uptake of CP-I in vitro, with an estimated Ki of 3.93 μM. Baseline CP-I concentrations were simulated to be 0.81 ± 0.26 ng/ml and determined to be 0.72 ± 0.16 ng/ml among metastatic prostate cancer patients, both of which were higher than those observed for healthy subjects. PBPK simulations revealed an absence of OATP1B3-mediated interaction between abiraterone and CP-I. Our clinical observations confirmed that CP-I concentrations remained comparable to baseline levels up to 12 weeks post 500 mg AA treatment. Using CP-I as an endogenous biomarker, we identified the inhibition of abiraterone on OATP1B3 but not OATP1B1 in vitro, which was predicted and observed to be clinically insignificant. We concluded that the interaction risk between AA and substrates of OATP1Bs is low.

SIGNIFICANCE STATEMENT

The authors used the endogenous biomarker coproporphyrin I (CP-I) and identified abiraterone as a moderate inhibitor of organic anion transporting polypeptide (OATP) 1B3 in vitro. Subsequent physiologically based pharmacokinetic (PBPK) simulations and clinical observations suggested an absence of OATP1B-mediated interaction between abiraterone and CP-I among prostate cancer patients. This multipronged study concluded that the interaction risk between abiraterone acetate and substrates of OATP1Bs is low, demonstrating the application of PBPK-CP-I modeling in predicting OATP1B-mediated interaction implicating abiraterone.




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Functional Characterization of Reduced Folate Carrier and Protein-Coupled Folate Transporter for Antifolates Accumulation in Non-Small Cell Lung Cancer Cells [Articles]

Antifolates are important for chemotherapy in non–small cell lung cancer (NSCLC). They mainly rely on reduced folate carrier (RFC) and proton-coupled folate transporter (PCFT) to enter cells. PCFT is supposed to be the dominant transporter of the two in tumors, as it operates optimally at acidic pH and has limited transport activity at physiological pH, whereas RFC operates optimally at neutral pH. In this study, we found RFC showed a slightly pH-dependent uptake of antifolates, with similar affinity values at pH 7.4 and 6.5. PCFT showed a highly pH-dependent uptake of antifolates, with an optimum pH of 6.0 for pemetrexed and 5.5 for methotrexate. The Michaelis-Menten constant (Km) value of PCFT for pemetrexed at pH 7.4 was more than 10 times higher than that at pH 6.5. Interestingly, we found that antifolate accumulations mediated by PCFT at acidic pH were significantly affected by the efflux transporter, breast cancer resistance protein (BCRP). The highest pemetrexed concentration was observed at pH 7.0–7.4 after a 60-minute accumulation in PCFT-expressing cells, which was further evidenced by the cytotoxicity of pemetrexed, with the IC50 value of pemetrexed at pH 7.4 being one-third of that at pH 6.5. In addition, the in vivo study indicated that increasing PCFT and RFC expression significantly enhanced the antitumor efficacy of pemetrexed despite the high expression of BCRP. These results suggest that both RFC and PCFT are important for antifolates accumulation in NSCLC, although there is an acidic microenvironment and high BCRP expression in tumors.

SIGNIFICANCE STATEMENT

Evaluating the role of reduced folate carrier (RFC) and proton-coupled folate transporter (PCFT) on antifolates accumulation in non–small cell lung cancer (NSCLC) is necessary for new drug designs. By using cell models, we found both RFC and PCFT were important for antifolates accumulation in NSCLC. Breast cancer resistance protein (BCRP) significantly affected PCFT-mediated antifolates accumulation at acidic pH but not RFC-mediated pemetrexed accumulation at physiological pH. High expression of PCFT or RFC enhanced the cytotoxicity and antitumor effect of pemetrexed.




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Molecular Mechanisms for the Selective Transport of Dichlorofluorescein by Human Organic Anion Transporting Polypeptide 1B1 [Articles]

Human organic anion transporting polypeptide (OATP) 1B1 and 1B3 are two highly homologous liver-specific uptake transporters. However, 2’,7’-dichlorofluorescein (DCF) is preferably transported by OATP1B1. In the present study, the molecular mechanisms for the selective transport of DCF by OATP1B1 were investigated by constructing and characterizing an array of OATP1B1/1B3 chimeras and site-directed mutagenesis. Our results show that transmembrane domain (TM) 10 is crucial for the surface expression and function of OATP1B1, in which Q541 and L545 play the most important roles in DCF transport. Replacement of TM10 in OATP1B1 with its OATP1B3 counterpart led to OATP1B1’s complete intracellular retention. Q541 and L545 may interact with DCF directly via hydrogen bonding and hydrophobic interactions. The decrease of DCF uptake by Q541A and L545S was due to their reduced binding affinity for DCF as compared with OATP1B1. In addition, Q541 and L545 are also crucial for the transport of estradiol-17β-glucuronide (E17βG) but not for the transport of estrone-3-sulfate (E3S), indicating different interaction modes between DCF/E17βG and E3S in OATP1B1. Taken together, Q541 and L545 in TM10 are critical for OATP1B1-mediated DCF uptake, but their effect is substrate-dependent.

SIGNIFICANCE STATEMENT

The key TMs and amino acid residues for the selective transport of DCF by OATP1B1 were identified. TM10 is crucial for the surface expression and function of OATP1B1. Within TM10, Q541 and L545 played the most significant roles and affected the function of OATP1B1 in a substrate-dependent manner. This information is crucial for a better understanding of the mechanism of the multispecificity of OATP1B1 and as a consequence the mechanism of OATP1B1-mediated drug–drug interactions.




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The Simultaneous Inhibition of Solute Carrier Family 6 Member 19 and Breast Cancer Resistance Protein Transporters Leads to an Increase of Indoxyl Sulfate (a Uremic Toxin) in Plasma and Kidney [Articles]

Solute carrier family 6 member 19 (SLC6A19) inhibitors are being studied as therapeutic agents for phenylketonuria. In this work, a potent SLC6A19 inhibitor (RA836) elevated rat kidney uremic toxin indoxyl sulfate (IDS) levels by intensity (arbitrary unit) of 13.7 ± 7.7 compared with vehicle 0.3 ± 0.1 (P = 0.01) as determined by tissue mass spectrometry imaging analysis. We hypothesized that increased plasma and kidney levels of IDS could be caused by the simultaneous inhibition of both Slc6a19 and a kidney IDS transporter responsible for excretion of IDS into urine. To test this, we first confirmed the formation of IDS through tryptophan metabolism by feeding rats a Trp-free diet. Inhibiting Slc6a19 with RA836 led to increased IDS in these rats. Next, RA836 and its key metabolites were evaluated in vitro for inhibiting kidney transporters such as organic anion transporter (OAT)1, OAT3, and breast cancer resistance protein (BCRP). RA836 inhibits BCRP with an IC50 of 0.045 μM but shows no significant inhibition of OAT1 or OAT3. Finally, RA836 analogs with either potent or no inhibition of SLC6A19 and/or BCRP were synthesized and administered to rats fed a normal diet. Plasma and kidney samples were collected to quantify IDS using liquid chromatography–mass spectrometry. Neither a SLC6A19 inactive but potent BCRP inhibitor nor a SLC6A19 active but weak BCRP inhibitor raised IDS levels, whereas compounds inhibiting both transporters caused IDS accumulation in rat plasma and kidney, supporting the hypothesis that rat Bcrp contributes to the excretion of IDS. In summary, we identified that inhibiting Slc6a19 increases IDS formation, while simultaneously inhibiting Bcrp results in IDS accumulation in the kidney and plasma.

SIGNIFICANCE STATEMENT

This is the first publication to decipher the mechanism for accumulation of indoxyl sulfate (IDS) (a uremic toxin) in rats via inhibition of both Slc6a19 and Bcrp. Specifically, inhibition of Slc6a19 in the gastrointestinal track increases IDS formation, and inhibition of Bcrp in the kidney blocks IDS excretion. Therefore, we should avoid inhibiting both solute carrier family 6 member 19 and breast cancer resistance protein simultaneously in humans to prevent accumulation of IDS, a known risk factor for cardiovascular disease, psychic anxiety, and mortality in chronic kidney disease patients.




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Ontogeny of Hepatic Organic Cation Transporter-1 in Rat and Human [Articles]

The organic cation transporter (OCT)-1 mediates hepatic uptake of cationic endogenous compounds and xenobiotics. To date, limited information exists on how Oct1/OCT1 functionally develops with age in rat and human livers and how this would affect the pharmacokinetics of OCT substrates in children or juvenile animals. The functional ontogeny of rOct/hOCT was profiled in suspended rat (2–57 days old) and human hepatocytes (pediatric liver tissue donors: age 2–12 months) by determining uptake clearance of 4-[4-(dimethylamino)styryl]-N-methylpyridinium iodide (ASP+) as a known rOct/hOCT probe substrate. mRNA expression was determined in rat liver tissue corresponding to rat ages used in the functional studies, while hOCT1 mRNA expressions were determined in the same hepatocyte batches as those used for uptake studies. Maturation of rOct/hOCT activity and expression were evaluated by comparing values obtained at the various ages to the adult values. Relative to adult values (at 8 weeks), ASP+ uptake clearance in suspended rat hepatocytes aged 0, 1, 2, 3, 4, 5, and 6 weeks reached 26%, 29%, 33%, 37%, 72%, 63%, and 71%, respectively. Hepatic Oct1 mRNA expression was consistent with Oct activity (correlation coefficient of 0.92). In human hepatocytes, OCT1 activity was age dependent and also correlated with mRNA levels (correlation coefficient of 0.88). These data show that Oct1/OCT1 activities and expression mature gradually in rat/human liver, thereby mirroring the expression pattern of organic anion transporting polypeptide in rat. These high-resolution transporter ontogeny profiles will allow for more accurate prediction of the pharmacokinetics of OCT1/Oct1 substrates in pediatric populations and juvenile animals.

SIGNIFICANCE STATEMENT

Organic cation transporter-1 (OCT1) represents a major drug uptake transporter in human liver. This study provides high-resolution data regarding the age-dependent function of OCT1 in the liver, based on in vitro experiments with rat and human hepatocytes obtained from donors between birth and adulthood. These ontogeny profiles will inform improved age-specific physiologically based pharmacokinetic models for OCT1 drug substrates in neonates, infants, children, and adults.




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The Induction of Drug Uptake Transporter Organic Anion Transporting Polypeptide 1A2 by Radiation Is Mediated by the Nonreceptor Tyrosine Kinase v-YES-1 Yamaguchi Sarcoma Viral Oncogene Homolog 1 [Articles]

Organic anion transporting polypeptides (OATP, gene symbol SLCO) are well-recognized key determinants for the absorption, distribution, and excretion of a wide spectrum of endogenous and exogenous compounds including many antineoplastic agents. It was therefore proposed as a potential drug target for cancer therapy. In our previous study, it was found that low-dose X-ray and carbon ion irradiation both upregulated the expression of OATP family member OATP1A2 and in turn, led to a more dramatic killing effect when cancer cells were cotreated with antitumor drugs such as methotrexate. In the present study, the underlying mechanism of the phenomenon was explored in breast cancer cell line MCF-7. It was found that the nonreceptor tyrosine kinase v-YES-1 Yamaguchi sarcoma viral oncogene homolog 1 (YES-1) was temporally coordinated with the change of OATP1A2 after irradiation. The overexpression of YES-1 significantly increased OATP1A2 both at the mRNA and protein level. The signal transducer and activator of transcription 3 (STAT3) pathway is likely the downstream target of YES-1 because phosphorylation and nuclear accumulation of STAT3 were both enhanced after overexpressing YES-1 in MCF-7 cells. Further investigation revealed that there are two possible binding sites of STAT3 localized at the upstream sequence of SLCO1A2, the encoding gene of OATP1A2. Electrophoretic mobility shift assay and chromatin immunoprecipitation analysis suggested that these two sites bound to STAT3 specifically and the overexpression of YES-1 significantly increased the association of the transcription factor with the putative binding sites. Finally, inhibition or knockdown of YES-1 attenuated the induction effect of radiation on the expression of OATP1A2.

SIGNIFICANCE STATEMENT

The present study found that the effect of X-rays on v-YES-1 Yamaguchi sarcoma viral oncogene homolog 1 (YES-1) and organic anion transporting polypeptides (OATP)1A2 was temporally coordinated. YES-1 phosphorylates and increases the nuclear accumulation of signal transducer and activator of transcription 3, which in turn binds to the upstream regulatory sequences of SLCO1A2, the coding gene for OATP1A2. Hence, inhibitors of YES-1 may suppress the radiation induction effect on OATP1A2.




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Roles of the ABCG2 Transporter in Protoporphyrin IX Distribution and Toxicity [Special Section on New and Emerging Areas and Technologies in Drug Metabolism and Disposition, Part II-Minireview]

ATP-binding cassette transporter subfamily G member 2 (ABCG2) is a membrane-bound transporter responsible for the efflux of various xenobiotics and endobiotics, including protoporphyrin IX (PPIX), an intermediate in the heme biosynthesis pathway. Certain genetic mutations and chemicals impair the conversion of PPIX to heme and/or increase PPIX production, leading to PPIX accumulation and toxicity. In mice, deficiency of ABCG2 protects against PPIX-mediated phototoxicity and hepatotoxicity by modulating PPIX distribution. In addition, in vitro studies revealed that ABCG2 inhibition increases the efficacy of PPIX-based photodynamic therapy by retaining PPIX inside target cells. In this review, we discuss the roles of ABCG2 in modulating the tissue distribution of PPIX, PPIX-mediated toxicity, and PPIX-based photodynamic therapy.

SIGNIFICANCE STATEMENT

This review summarized the roles of ABCG2 in modulating PPIX distribution and highlighted the therapeutic potential of ABCG2 inhibitors for the management of PPIX-mediated toxicity.




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Differential Tissue Abundance of Membrane-Bound Drug Metabolizing Enzymes and Transporter Proteins by Global Proteomics [Special Section on New and Emerging Areas and Technologies in Drug Metabolism and Disposition, Part II]

Protein abundance data of drug-metabolizing enzymes and transporters (DMETs) are useful for scaling in vitro and animal data to humans for accurate prediction and interpretation of drug clearance and toxicity. Targeted DMET proteomics that relies on synthetic stable isotope-labeled surrogate peptides as calibrators is routinely used for the quantification of selected proteins; however, the technique is limited to the quantification of a small number of proteins. Although the global proteomics-based total protein approach (TPA) is emerging as a better alternative for large-scale protein quantification, the conventional TPA does not consider differential sequence coverage by identifying unique peptides across proteins. Here, we optimized the TPA approach by correcting protein abundance data by the sequence coverage, which was applied to quantify 54 DMETs for characterization of 1) differential tissue DMET abundance in the human liver, kidney, and intestine, and 2) interindividual variability of DMET proteins in individual intestinal samples (n = 13). Uridine diphosphate-glucuronosyltransferase 2B7 (UGT2B7), microsomal glutathione S-transferases (MGST1, MGST2, and MGST3) carboxylesterase 2 (CES2), and multidrug resistance-associated protein 2 (MRP2) were expressed in all three tissues, whereas, as expected, four cytochrome P450s (CYP3A4, CYP3A5, CYP2C9, and CYP4F2), UGT1A1, UGT2B17, CES1, flavin-containing monooxygenase 5, MRP3, and P-glycoprotein were present in the liver and intestine. The top three DMET proteins in individual tissues were: CES1>CYP2E1>UGT2B7 (liver), CES2>UGT2B17>CYP3A4 (intestine), and MGST1>UGT1A6>MGST2 (kidney). CYP3A4, CYP3A5, UGT2B17, CES2, and MGST2 showed high interindividual variability in the intestine. These data are relevant for enhancing in vitro to in vivo extrapolation of drug absorption and disposition and can be used to enhance the accuracy of physiologically based pharmacokinetic prediction of systemic and tissue concentration of drugs.

SIGNIFICANCE STATEMENT

This study quantified the abundance and compositions of drug-metabolizing enzymes and transporters in pooled human liver, intestine, and kidney microsomes as well as individual intestinal microsomes using an optimized global proteomics approach. The data revealed large intertissue differences in the abundance of these proteins and high intestinal interindividual variability in the levels of cytochrome P450s (e.g., CYP3A4 and CYP3A5), uridine diphosphate-glucuronosyltransferase 2B17, carboxylesterase 2, and microsomal glutathione S-transferase 2. These data are applicable for the prediction of first-pass metabolism and tissue-specific drug clearance.




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Development and Piloting of Implementation Strategies to Support Delivery of a Clinical Intervention for Postpartum Hemorrhage in Four sub-Saharan Africa Countries

ABSTRACTIntroduction:Postpartum hemorrhage (PPH) remains the leading cause of maternal mortality. A new clinical intervention (E-MOTIVE) holds the potential to improve early PPH detection and management. We aimed to develop and pilot implementation strategies to support uptake of this intervention in Kenya, Nigeria, South Africa, and Tanzania.Methods:Implementation strategy development: We triangulated findings from qualitative interviews, surveys and a qualitative evidence synthesis to identify current PPH care practices and influences on future intervention implementation. We mapped influences using implementation science frameworks to identify candidate implementation strategies before presenting these at stakeholder consultation and design workshops to discuss feasibility, acceptability, and local adaptations. Piloting: The intervention and implementation strategies were piloted in 12 health facilities (3 per country) over 3 months. Interviews (n=58), case report forms (n=1,269), and direct observations (18 vaginal births, 7 PPHs) were used to assess feasibility, acceptability, and fidelity.Results:Implementation strategy development: Key influences included shortages of drugs, supplies, and staff, limited in-service training, and perceived benefits of the intervention (e.g., more accurate PPH detection and reduced PPH mortality). Proposed implementation strategies included a PPH trolley, on-site simulation-based training, champions, and audit and feedback. Country-specific adaptations included merging the E-MOTIVE intervention with national maternal health trainings, adapting local PPH protocols, and PPH trollies depending on staff needs. Piloting: Intervention and implementation strategy fidelity differed within and across countries. Calibrated drapes resulted in earlier and more accurate PPH detection but were not consistently used at the start. Implementation strategies were feasible to deliver; however, some instances of limited use were observed (e.g., PPH trolley and skills practice after training).Conclusion:Systematic intervention development, piloting, and process evaluation helped identify initial challenges related to intervention fidelity, which were addressed ahead of a larger-scale effectiveness evaluation. This has helped maximize the internal validity of the trial.




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Factors Influencing the Central Nervous System (CNS) Distribution of the Ataxia Telangiectasia Mutated and Rad3-Related Inhibitor Elimusertib (BAY1895344): Implications for the Treatment of CNS Tumors [Metabolism, Transport, and Pharmacogenetics]

Glioblastoma (GBM) is a disease of the whole brain, with infiltrative tumor cells protected by an intact blood-brain barrier (BBB). GBM has a poor prognosis despite aggressive treatment, in part due to the lack of adequate drug permeability at the BBB. Standard of care GBM therapies include radiation and cytotoxic chemotherapy that lead to DNA damage. Subsequent activation of DNA damage response (DDR) pathways can induce resistance. Various DDR inhibitors, targeting the key regulators of these pathways such as ataxia telangiectasia mutated and Rad3-related (ATR), are being explored as radio- and chemosensitizers. Elimusertib, a novel ATR kinase inhibitor, can prevent repair of damaged DNA, increasing efficacy of DNA-damaging cytotoxic therapies. Robust synergy was observed in vitro when elimusertib was combined with the DNA-damaging agent temozolomide; however, we did not observe improvement with this combination in in vivo efficacy studies in GBM orthotopic tumor-bearing mice. This in vitro–in vivo disconnect was explored to understand factors influencing central nervous system (CNS) distribution of elimusertib and reasons for lack of efficacy. We observed that elimusertib is rapidly cleared from systemic circulation in mice and would not maintain adequate exposure in the CNS for efficacious combination therapy with temozolomide. CNS distribution of elimusertib is partially limited by P-glycoprotein efflux at the BBB, and high binding to CNS tissues leads to low levels of pharmacologically active (unbound) drug in the brain. Acknowledging the potential for interspecies differences in pharmacokinetics, these data suggest that clinical translation of elimusertib in combination with temozolomide for treatment of GBM may be limited.

SIGNIFICANCE STATEMENT

This study examined the disconnect between the in vitro synergy and in vivo efficacy of elimusertib/temozolomide combination therapy by exploring systemic and central nervous system (CNS) distributional pharmacokinetics. Results indicate that the lack of improvement in in vivo efficacy in glioblastoma (GBM) patient-derived xenograft (PDX) models could be attributed to inadequate exposure of pharmacologically active drug concentrations in the CNS. These observations can guide further exploration of elimusertib for the treatment of GBM or other CNS tumors.




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Nonclinical Profile of PF-06952229 (MDV6058), a Novel TGF{beta}RI/Activin Like Kinase 5 Inhibitor Supports Clinical Evaluation in Cancer [Drug Discovery and Translational Medicine]

The development of transforming growth factor βreceptor inhibitors (TGFβRi) as new medicines has been affected by cardiac valvulopathy and arteriopathy toxicity findings in nonclinical toxicology studies. PF-06952229 (MDV6058) selected using rational drug design is a potent and selective TGFβRI inhibitor with a relatively clean off-target selectivity profile and good pharmacokinetic properties across species. PF-06952229 inhibited clinically translatable phospho-SMAD2 biomarker (≥60%) in human and cynomolgus monkey peripheral blood mononuclear cells, as well as in mouse and rat splenocytes. Using an optimized, intermittent dosing schedule (7-day on/7-day off/cycle; 5 cycles), PF-06952229 demonstrated efficacy in a 63-day syngeneic MC38 colon carcinoma mouse model. In the pivotal repeat-dose toxicity studies (rat and cynomolgus monkey), PF-06952229 on an intermittent dosing schedule (5-day on/5-day off cycle; 5 cycles, 28 doses) showed no cardiac-related adverse findings. However, new toxicity findings related to PF-06952229 included reversible hepatocellular (hepatocyte necrosis with corresponding clinically monitorable transaminase increases) and lung (hemorrhage with mixed cell inflammation) findings at ≥ targeted projected clinical efficacious exposures. Furthermore, partially reversible cartilage hypertrophy (trachea and femur in rat; femur in monkey) and partially to fully reversible, clinically monitorable decreases in serum phosphorus and urinary phosphate at ≥ projected clinically efficacious exposures were observed. Given the integral role of TGFβ in endochondral bone formation, cartilage findings in toxicity studies have been observed with other TGFβRi classes of compounds. The favorable cumulative profile of PF-06952229 in biochemical, pharmacodynamic, pharmacokinetic, and nonclinical studies allowed for its evaluation in cancer patients using the intermittent dosing schedule (7-day on/7-day off) and careful protocol-defined monitoring.

SIGNIFICANCE STATEMENT

Only a few TGFβRi have progressed for clinical evaluation due to adverse cardiac findings in pivotal nonclinical toxicity studies. The potential translations of such findings in patients are of major concern. Using a carefully optimized intermittent dosing schedule, PF-06952229 has demonstrated impressive pharmacological efficacy in the syngeneic MC38 colon carcinoma mouse model. Additionally, a nonclinical toxicology package without cardiovascular liabilities and generally monitorable toxicity profile has been completed. The compound presents an acceptable International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use S9-compliant profile for the intended-to-treat cancer patients.




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Effects of Dual Inhibition at Dopamine Transporter and {sigma} Receptors in the Discriminative-Stimulus Effects of Cocaine in Male Rats [Behavioral Pharmacology]

Previous studies demonstrated that sigma receptor (R) antagonists alone fail to alter cocaine self-administration despite blocking various other effects of cocaine. However, R antagonists when combined with dopamine transporter (DAT) inhibitors substantially decrease cocaine self-administration. To better understand the effects of this combination, the present study examined the effects of R antagonist and DAT inhibitor combinations in male rats discriminating cocaine (10 mg/kg, i.p.) from saline injections. The DAT inhibitors alone [(–)-2-β-carbomethoxy-3-β-(4-fluorophenyl)tropane 1,5-naphthalenedisulfonate monohydrate (WIN 35,428) and methylphenidate] at low (0.1-mg/kg) doses that were minimally active failed to shift the dose-effect function for discriminative-stimulus effects of cocaine to the left more than 2-fold. At 0.32 mg/kg the DAT inhibitors alone shifted the cocaine dose-effect function leftward 24- or 6.6-fold, respectively. The R antagonists (BD1008, BD1047, and BD1063) failed to fully substitute for cocaine, although BD1008 and BD1047 substituted partially. At 10 mg/kg, BD1008, BD1047, or BD1063 alone shifted the cocaine dose-effect function leftward less than 6.0-fold. In combination with 0.1 mg/kg WIN 35,428, the 10 mg/kg doses of R antagonists shifted the cocaine dose-effect function from 12.3- to 36.7-fold leftward, and with 0.32 mg/kg WIN 35,428 from 14.3- to 440-fold leftward. In combination with 0.1 mg/kg methylphenidate, those R antagonist doses shifted the cocaine dose-effect function from 5.5- to 55.0-fold leftward, and with 0.32 mg/kg methylphenidate from 10.5- to 48.1-fold leftward. The present results suggest that dual DAT/R inhibition produces agonist-like subjective effects that may promote decreases in self-administration obtained in previous studies.

SIGNIFICANCE STATEMENT

There is currently no approved medication for treating stimulant abuse, although dopamine uptake inhibitors in combination with sigma receptor (R) antagonists decrease cocaine self-administration in laboratory animals. The present study assessed how this combination alters the discriminative-stimulus effects of cocaine in male rats. Results suggest that concurrent dopamine uptake inhibition and R antagonism together may promote decreases in self-administration, possibly by mimicking the subjective effects extant when subjects cease continued cocaine self-administration.




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Cannabis and Cannabinoid Signaling: Research Gaps and Opportunities [Special Section: Cannabinoid Signaling in Human Health and Disease-Commentary]

Cannabis and its products have been used for centuries for both medicinal and recreational purposes. The recent widespread legalization of cannabis has vastly expanded its use in the United States across all demographics except for adolescents. Meanwhile, decades of research have advanced our knowledge of cannabis pharmacology and particularly of the endocannabinoid system with which the components of cannabis interact. This research has revealed multiple targets and approaches for manipulating the system for therapeutic use and to ameliorate cannabis toxicity or cannabis use disorder. Research has also led to new questions that underscore the potential risks of its widespread use, particularly the enduring consequences of exposure during critical windows of brain development or for consumption of large daily doses of cannabis with high content 9-tetrahydrocannabinol. This article highlights current neuroscience research on cannabis that has shed light on therapeutic opportunities and potential adverse consequences of misuse and points to gaps in knowledge that can guide future research.

SIGNIFICANCE STATEMENT

Cannabis use has escalated with its increased availability. Here, the authors highlight the challenges of cannabis research and the gaps in our knowledge of cannabis pharmacology and of the endocannabinoid system that it targets. Future research that addresses these gaps is needed so that the endocannabinoid system can be leveraged for safe and effective use.




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Neuroactive Kynurenines as Pharmacological Targets: New Experimental Tools and Exciting Therapeutic Opportunities [75th Anniversary Celebration Collection Special Section]

Both preclinical and clinical studies implicate functional impairments of several neuroactive metabolites of the kynurenine pathway (KP), the major degradative cascade of the essential amino acid tryptophan in mammals, in the pathophysiology of neurologic and psychiatric diseases. A number of KP enzymes, such as tryptophan 2,3-dioxygenase (TDO2), indoleamine 2,3-dioxygenases (IDO1 and IDO2), kynurenine aminotransferases (KATs), kynurenine 3-monooxygenase (KMO), 3-hydroxyanthranilic acid oxygenase (3-HAO), and quinolinic acid phosphoribosyltransferase (QPRT), control brain KP metabolism in health and disease and are therefore increasingly considered to be promising targets for the treatment of disorders of the nervous system. Understanding the distribution, cellular expression, and regulation of KP enzymes and KP metabolites in the brain is therefore critical for the conceptualization and implementation of successful therapeutic strategies.

Significance Statement

Studies have implicated the kynurenine pathway of tryptophan in the pathophysiology of neurologic and psychiatric diseases. Key enzymes of the kynurenine pathway regulate brain metabolism in both health and disease, making them promising targets for treating these disorders. Therefore, understanding the distribution, cellular expression, and regulation of these enzymes and metabolites in the brain is critical for developing effective therapeutic strategies. This review endeavors to describe these processes in detail.:




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Low-Field (64 mT) Portable MRI for Rapid Point-of-Care Diagnosis of Dissemination in Space in Patients Presenting with Optic Neuritis [CLINICAL PRACTICE]

BACKGROUND AND PURPOSE:

Low-field 64 mT portable brain MRI has recently shown diagnostic promise for MS. This study aimed to evaluate the utility of portable MRI (pMRI) in assessing dissemination in space (DIS) in patients presenting with optic neuritis and determine whether deploying pMRI in the MS clinic can shorten the time from symptom onset to MRI.

MATERIALS AND METHODS:

Newly diagnosed patients with optic neuritis referred to a tertiary academic MS center from July 2022 to January 2024 underwent both point-of-care pMRI and subsequent 3T conventional MRI (cMRI). Images were evaluated for periventricular (PV), juxtacortical (JC), and infratentorial (IT) lesions. DIS was determined on brain MRI per 2017 McDonald criteria. Test characteristics were computed by using cMRI as the reference. Interrater and intermodality agreement between pMRI and cMRI were evaluated by using the Cohen . Time from symptom onset to pMRI and cMRI during the study period was compared with the preceding 1.5 years before pMRI implementation by using Kruskal-Wallis with post hoc Dunn tests.

RESULTS:

Twenty patients (median age: 32.5 years [interquartile range {IQR}, 28–40]; 80% women) were included, of whom 9 (45%) and 5 (25%) had DIS on cMRI and pMRI, respectively. Median time interval between pMRI and cMRI was 7 days (IQR, 3.5–12.5). Interrater agreement was very good for PV (95%, = 0.89), and good for JC and IT lesions (90%, = 0.69 for both). Intermodality agreement was good for PV (90%, = 0.80) and JC (85%, = 0.63), and moderate for IT lesions (75%, = 0.42) and DIS (80%, = 0.58). pMRI had a sensitivity of 56% and specificity of 100% for DIS. The median time from symptom onset to pMRI was significantly shorter (8.5 days [IQR 7–12]) compared with the interval to cMRI before pMRI deployment (21 days [IQR 8–49], n = 50) and after pMRI deployment (15 days [IQR 12–29], n = 30) (both P < .01). Time from symptom onset to cMRI in those periods was not significantly different (P = .29).

CONCLUSIONS:

In patients with optic neuritis, pMRI exhibited moderate concordance, moderate sensitivity, and high specificity for DIS compared with cMRI. Its integration into the MS clinic reduced the time from symptom onset to MRI. Further studies are warranted to evaluate the role of pMRI in expediting early MS diagnosis and as an imaging tool in resource-limited settings.




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The diagnostic odyssey of a patient with dihydropyrimidinase deficiency: a case report and review of the literature [RESEARCH REPORT]

Dihydropyrimidinase (DHP) deficiency is an autosomal recessive metabolic disorder caused by biallelic pathogenic variants of DPYS. Patients with DHP deficiency exhibit a broad spectrum of phenotypes, ranging from severe neurological and gastrointestinal involvement to cases with no apparent symptoms. The biochemical diagnosis of DHP deficiency is based on the detection of a significant amount of dihydropyrimidines in urine, plasma, and cerebrospinal fluid samples. Molecular genetic testing, specifically the identification of biallelic pathogenic variants in DPYS, has proven instrumental in confirming the diagnosis and facilitating family studies. This case study documents the diagnostic journey of an 18-yr-old patient with DHP deficiency, highlighting features at the severe end of the clinical spectrum. Notably, our patient exhibited previously unreported skeletal features that positively responded to bisphosphonate treatment, contributing valuable insights to the clinical characterization of DHP deficiency. Additionally, a novel DPYS variant was identified and confirmed pathogenicity through metabolic testing, further expanding the variant spectrum of the gene. Our case emphasizes the importance of a comprehensive diagnostic approach using genetic sequencing and metabolic testing for accurate diagnosis.




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PD-L1+ diffuse large B-cell lymphoma with extremely high mutational burden and microsatellite instability due to acquired PMS2 mutation [RESEARCH REPORT]

We present a unique case of a single patient presenting with two mutationally distinct, PD-L1+ diffuse large B-cell lymphomas (DLBCLs). One of these DLBCLs demonstrated exceptionally high mutational burden (eight disease-associated variants and 41 variants of undetermined significance) with microsatellite instability (MSI) and an acquired PMS2 mutation with loss of PMS2 protein expression, detected postchemotherapy. This report, while highlighting the extent of possible tumor heterogeneity across separate clonal expansions as well as possible syndromic B-cell neoplasia, supports the notion that, although rare, PD-L1 expression and associated states permissive of high mutational burden (such as mismatch repair gene loss of function/MSI) should be more routinely considered in DLBCLs. Appropriate testing may be predictive of outcome and inform the utility of targeted therapy in these genetically diverse and historically treatment-refractory malignancies.




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Deep molecular tracking over the 12-yr development of endometrial cancer from hyperplasia in a single patient [RESEARCH REPORT]

Although the progressive histologic steps leading to endometrial cancer (EndoCA), the most common female reproductive tract malignancy, from endometrial hyperplasia are well-established, the molecular changes accompanying this malignant transformation in a single patient have never been described. We had the unique opportunity to investigate the paired histologic and molecular features associated with the 12-yr development of EndoCA in a postmenopausal female who could not undergo hysterectomy and instead underwent progesterone treatment. Using a specially designed 58-gene next-generation sequencing panel, we analyzed a total of 10 sequential biopsy samples collected over this time frame. A total of eight pathogenic/likely pathogenic mutations in seven genes, APC, ARID1A, CTNNB1, CDKN2A, KRAS, PTEN, and TP53, were identified. A PTEN nonsense mutation p.W111* was present in all samples analyzed except histologically normal endometrium. Apart from this PTEN mutation, the only other recurrent mutation was KRAS G12D, which was present in six biopsy samplings, including histologically normal tissue obtained at the patient's first visit but not detectable in the cancer. The PTEN p.W111* mutant allele fractions were lowest in benign, inactive endometrial glands (0.7%), highest in adenocarcinoma (36.9%), and, notably, were always markedly reduced following progesterone treatment. To our knowledge, this report provides the first molecular characterization of EndoCA development in a single patient. A single PTEN mutation was present throughout the 12 years of cancer development. Importantly, and with potential significance toward medical and nonsurgical management of EndoCA, progesterone treatments were consistently noted to markedly decrease PTEN mutant allele fractions to precancerous levels.




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Pazopanib elicits remarkable response in metastatic porocarcinoma: a functional precision medicine approach [RESEARCH REPORT]

Metastatic porocarcinomas (PCs) are vanishingly rare, highly aggressive skin adnexal tumors with mortality rates exceeding 70%. Their rarity has precluded the understanding of their disease pathogenesis, let alone the conduct of clinical trials to evaluate treatment strategies. There are no effective agents for unresectable PCs. Here, we successfully demonstrate how functional precision medicine was implemented in the clinic for a metastatic PC with no known systemic treatment options. Comprehensive genomic profiling of the tumor specimen did not yield any actionable genomic aberrations. However, ex vivo drug testing predicted pazopanib efficacy, and indeed, administration of pazopanib elicited remarkable clinicoradiological response. Pazopanib and its class of drugs should be evaluated for efficacy in other cases of PC, and the rationale for efficacy should be determined when PC tumor models become available. A functional precision medicine approach could be useful to derive effective treatment options for rare cancers.




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Prostate cancer patient stratification by molecular signatures in the Veterans Precision Oncology Data Commons [RESEARCH REPORT]

Veterans are at an increased risk for prostate cancer, a disease with extraordinary clinical and molecular heterogeneity, compared with the general population. However, little is known about the underlying molecular heterogeneity within the veteran population and its impact on patient management and treatment. Using clinical and targeted tumor sequencing data from the National Veterans Affairs health system, we conducted a retrospective cohort study on 45 patients with advanced prostate cancer in the Veterans Precision Oncology Data Commons (VPODC), most of whom were metastatic castration-resistant. We characterized the mutational burden in this cohort and conducted unsupervised clustering analysis to stratify patients by molecular alterations. Veterans with prostate cancer exhibited a mutational landscape broadly similar to prior studies, including KMT2A and NOTCH1 mutations associated with neuroendocrine prostate cancer phenotype, previously reported to be enriched in veterans. We also identified several potential novel mutations in PTEN, MSH6, VHL, SMO, and ABL1. Hierarchical clustering analysis revealed two subgroups containing therapeutically targetable molecular features with novel mutational signatures distinct from those reported in the Catalogue of Somatic Mutations in Cancer database. The clustering approach presented in this study can potentially be used to clinically stratify patients based on their distinct mutational profiles and identify actionable somatic mutations for precision oncology.




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Novel pathogenic UQCRC2 variants in a female with normal neurodevelopment [RESEARCH REPORT]

Electron transport chain (ETC) disorders are a group of rare, multisystem diseases caused by impaired oxidative phosphorylation and energy production. Deficiencies in complex III (CIII), also known as ubiquinol–cytochrome c reductase, are particularly rare in humans. Ubiquinol–cytochrome c reductase core protein 2 (UQCRC2) encodes a subunit of CIII that plays a crucial role in dimerization. Several pathogenic UQCRC2 variants have been identified in patients presenting with metabolic abnormalities that include lactic acidosis, hyperammonemia, hypoglycemia, and organic aciduria. Almost all previously reported UQCRC2-deficient patients exhibited neurodevelopmental involvement, including developmental delays and structural brain anomalies. Here, we describe a girl who presented at 3 yr of age with lactic acidosis, hyperammonemia, and hypoglycemia but has not shown any evidence of neurodevelopmental dysfunction by age 15. Whole-exome sequencing revealed compound heterozygosity for two novel variants in UQCRC2: c.1189G>A; p.Gly397Arg and c.437T>C; p.Phe146Ser. Here, we discuss the patient's clinical presentation and the likely pathogenicity of these two missense variants.




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Rapid genome diagnosis of alveolar capillary dysplasia leading to treatment in a child with respiratory and cardiac failure [RESEARCH REPORT]

Alveolar capillary dysplasia (ACD) is a fatal disorder that typically presents in the neonatal period with refractory hypoxemia and pulmonary hypertension. Lung biopsy is traditionally required to establish the diagnosis. We report a 22-mo-old male who presented with anemia, severe pulmonary hypertension, and right heart failure. He had a complicated hospital course resulting in cardiac arrest and requirement for extracorporeal membrane oxygenation. Computed tomography of the chest showed a heterogenous pattern of interlobular septal thickening and pulmonary edema. The etiology of his condition was unknown, lung biopsy was contraindicated because of his medical fragility, and discussions were held to move to palliative care. Rapid whole-genome sequencing (rWGS) was performed. In 2 d it resulted, revealing a novel FOXF1 gene pathogenic variant that led to the presumptive diagnosis of atypical ACD. Cases of atypical ACD have been reported with survival in patients using medical therapy or lung transplantation. Based on the rWGS diagnosis and more favorable potential of atypical ACD, aggressive medical treatment was pursued. The patient was discharged home after 67 d in the hospital; he is currently doing well more than 30 mo after his initial presentation with only one subsequent hospitalization and no requirement for lung transplantation. Our case reveals the potential for use of rWGS in a critically ill child in which the diagnosis is unknown. rWGS and other advanced genetic tests can guide clinical management and expand our understanding of atypical ACD and other conditions.




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The importance of escalating molecular diagnostics in patients with low-grade pediatric brain cancer [PRECISION MEDICINE IN PRACTICE]

Pilocytic astrocytomas are the most common pediatric brain tumors, typically presenting as low-grade neoplasms. We report two cases of pilocytic astrocytoma with atypical tumor progression. Case 1 involves a 12-yr-old boy with an unresectable suprasellar tumor, negative for BRAF rearrangement but harboring a BRAF p.V600E mutation. He experienced tumor size reduction and stable disease following dabrafenib treatment. Case 2 describes a 6-yr-old boy with a thalamic tumor that underwent multiple resections, with no actionable driver detected using targeted next-generation sequencing. Whole-genome and RNA-seq analysis identified an internal tandem duplication in FGFR1 and RAS pathway activation. Future management options include FGFR1 inhibitors. These cases demonstrate the importance of escalating molecular diagnostics for pediatric brain cancer, advocating for early reflexing to integrative whole-genome sequencing and transcriptomic profiling when targeted panels are uninformative. Identifying molecular drivers can significantly impact treatment decisions and improve patient outcomes.




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Support for primary care prescribing for adult ADHD in England: national survey

BackgroundAttention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder, for which there are effective pharmacological treatments that improve symptoms and reduce complications. Guidelines published by the National Institute for Health and Care Excellence recommend that primary care practitioners prescribe medication for adult ADHD under shared-care agreements with Adult Mental Health Services (AMHS). However, provision remains uneven, with some practitioners reporting a lack of support.AimThis study aimed to describe elements of support, and their availability/use, in primary care prescribing for adult ADHD medication in England to improve access for this underserved population and inform service improvement.Design and settingCross-sectional surveys were used to elicit data from commissioners, health professionals (HPs), and people with lived experience of ADHD (LE) across England about elements supporting pharmacological treatment of ADHD in primary care.MethodThree interlinked cross-sectional surveys were used to ask every integrated care board in England (commissioners), along with convenience samples of HPs and LEs, about prescribing rates, AMHS availability, wait times, and shared-care agreement protocols/policies for the pharmacological treatment of ADHD in primary care. Descriptive analyses, percentages, and confidence intervals were used to summarise responses by stakeholder group. Variations in reported provision and practice were explored and displayed visually using mapping software.ResultsData from 782 responders (42 commissioners, 331 HPs, 409 LEs) revealed differences in reported provision by stakeholder group, including for prescribing (95% of HPs versus 64% of LEs). In all, >40% of responders reported extended AMHS wait times of ≥2 years. There was some variability by NHS region – for example, London had the lowest reported extended wait time (25%), while East of England had the highest (55%).ConclusionElements supporting appropriate shared-care prescribing of ADHD medication via primary care are not universally available in England. Coordinated approaches are needed to address these gaps.




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PBRNs: Past, Present, and Future: A NAPCRG Report on the Practice-Based Research Network Conference. [Family Medicine Updates]




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The Odyssey of HOMER: Comparative Effectiveness Research on Medication for Opioid Use Disorder During the COVID-19 Pandemic [Special Report]

The usual challenges of conducting primary care research, including randomized trials, have been exacerbated, and new ones identified, during the COVID-19 pandemic. HOMER (Home versus Office for Medication Enhanced Recovery; subsequently, Comparing Home, Office, and Telehealth Induction for Medication Enhanced Recovery) is a pragmatic, comparative-effectiveness research trial that aims to answer a key question from patients and clinicians: What is the best setting in which to start treatment with buprenorphine for opioid use disorder for this patient at this time? In this article, we describe the difficult journey to find the answer. The HOMER study began as a randomized trial comparing treatment outcomes in patients starting treatment with buprenorphine via induction at home (unobserved) vs in the office (observed, synchronous). The study aimed to enroll 1,000 participants from 100 diverse primary care practices associated with the State Networks of Colorado Ambulatory Practices and Partners and the American Academy of Family Physicians National Research Network. The research team faced unexpected challenges related to the COVID-19 pandemic and dramatic changes in the opioid epidemic. These challenges required changes to the study design, protocol, recruitment intensity, and funding conversations, as well as patience. As this is a participatory research study, we sought, documented, and responded to practice and patient requests for adaptations. Changes included adding a third study arm using telehealth induction (observed via telephone or video, synchronous) and switching to a comprehensive cohort design to answer meaningful patient-centered research questions. Using a narrative approach based on the Greek myth of Homer, we describe here the challenges and adaptations that have provided the opportunity for HOMER to thrive and find the way home. These clinical trial strategies may apply to other studies faced with similar cultural and extreme circumstances.




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Self-Reported PrEP Use and Risk of Bacterial STIs Among Ontarian Men Who Are Gay or Bisexual or Have Sex With Men [Original Research]

PURPOSE

HIV pre-exposure prophylaxis (PrEP) may increase rates of bacterial sexually transmitted infections (STIs) among gay, bisexual, and other men who have sex with men (GBM) through risk compensation (eg, an increase in condomless sex or number of partners); however, longitudinal studies exploring the time-dependent nature of PrEP uptake and bacterial STIs are limited. We used marginal structural models to estimate the effect of PrEP uptake on STI incidence.

METHODS

We analyzed data from the iCruise study, an online longitudinal study of 535 Ontarian GBM from July 2017 to April 2018, to estimate the effects of PrEP uptake on incidence of self-reported bacterial STIs (chlamydia, gonorrhea, and syphilis) collected with 12 weekly diaries. The incidence rate was calculated as the number of infections per 100 person-months, with evaluation of the STIs overall and individually. We used marginal structural models to account for time-varying confounding and quantitative bias analysis to evaluate the sensitivity of estimates to nondifferential outcome misclassification.

RESULTS

Participating GBM were followed up for a total of 1,623.5 person-months. Overall, 70 participants (13.1%) took PrEP during the study period. Relative to no uptake, PrEP uptake was associated with an increased incidence rate of gonorrhea (incidence rate ratio = 4.00; 95% CI, 1.67-9.58), but not of chlamydia or syphilis, and not of any bacterial STI overall. Accounting for misclassification, the median incidence rate ratio for gonorrhea was 2.36 (95% simulation interval, 1.08-5.06).

CONCLUSIONS

We observed an increased incidence rate of gonorrhea associated with PrEP uptake among Ontarian GBM that was robust to misclassification. Although our findings support current guidelines for integrating gonorrhea screening with PrEP services, additional research should consider the long-term impact of PrEP among this population.

Annals Early Access article




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Evaluation of the Importance of Capsule Transparency in Dry Powder Inhalation Devices [Research Briefs]

The aim of this work is to test whether the use of a transparent capsule affects the residual capsule weight after inhalation as a surrogate of the inhaled delivered dose for patients with non-reversible chronic airway disease. Researchers conducted an observational cross-sectional study with patients using a single-dose dry powder inhaler. The weight of the capsule was measured with a precision microbalance before and after inhalation. Ninety-one patients were included, of whom 63 (69.2%) used a transparent capsule. Inhalation with a transparent capsule achieved a weight decrease of 30.1% vs 8.6% for devices with an opaque capsule (P <0.001). These data reinforce the need to provide patients with mechanisms that verify the correct inhalation technique.




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[Evolutionary Biology] How Important Is Variation in Extrinsic Reproductive Isolation to the Process of Speciation?

The strength of reproductive isolation (RI) between two or more lineages during the process of speciation can vary by the ecological conditions. However, most speciation research has been limited to studying how ecologically dependent RI varies among a handful of broadly categorized environments. Very few studies consider the variability of RI and its effects on speciation at finer scales—that is, within each environment due to spatial or temporal environmental heterogeneity. Such variation in RI across time and/or space may inhibit speciation through leaky reproductive barriers or promote speciation by facilitating reinforcement. To investigate this overlooked aspect of speciation research, we conducted a literature review of existing studies of variation in RI in the field and then conducted individual-based simulations to examine how variation in hybrid fitness across time and space affects the degree of gene flow. Our simulations indicate that the presence of variation in hybrid fitness across space and time often leads to an increase in gene flow compared to scenarios where hybrid fitness remains static. This observation can be attributed to the convex relationship between the degree of gene flow and the strength of selection on hybrids. Our simulations also show that the effect of variation in RI on facilitating gene flow is most pronounced when RI, on average, is relatively low. This finding suggests that it could serve as an important mechanism to explain why the completion of speciation is often challenging. While direct empirical evidence documenting variation in extrinsic RI is limited, we contend that it is a prevalent yet underexplored phenomenon. We support this argument by proposing common scenarios in which RI is likely to exhibit variability and thus influence the process of speciation.





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Column: Why reporting from South Sudan is so difficult — and critically needed

Simona Foltyn walks down a mountain slope shortly after crossing into South Sudan. Photo by Jason Patinkin

In August, fellow reporter Jason Patinkin and I crossed on foot from northern Uganda into rebel-held South Sudan. Over the course of four days, we walked more than 40 miles through the bush, escorted by rebel soldiers, to shed light on one of the world’s most underreported conflicts.

Reporting on South Sudan’s war, which began in 2013, has always been a challenge due to the risk and logistical hurdles associated with accessing remote areas where fighting takes place. But over the past year, covering the war and its humanitarian fallout has become particularly difficult. Since the beginning of this year, South Sudan’s government has banned at least 20 foreign journalists in an apparent effort to silence reporters who had a track record of critically reporting on the government.

The war has had a devastating impact on South Sudanese communities, but much of it has remained out of the limelight of international media.

This systematic crackdown on the foreign press (South Sudanese journalists have long risked imprisonment and death for doing their work) coincided with two important developments. In November 2016, the United Nations warned that the violence being committed against civilians in the southern region of Equatoria risked spiraling into genocide. Then, in February, the UN declared a man-made famine, warning that 100,000 people were at risk of starving to death as a result of civil war.

Journalists seeking to cover these events were left with two equally unsavory options: self-censorship or a risky trip to rebel-held parts of the country. Only a handful of journalists have attempted the latter since fighting escalated in July last year. For us, this was our second embed with the rebels this year.

Martin Abucha (second from right) rests with his troops in rebel-held South Sudan. Photo by Jason Patinkin

We set off from a town in northern Uganda at five in the morning, bouncing along a bumpy dirt track towards the South Sudan border. Crammed into our four-wheel drive were rebel commander Martin Abucha, a dual American and South Sudanese citizen who we planned to profile for our PBS NewsHour Weekend segment, a couple of guides, and several duffle bags stuffed with our tents, sleeping bags, emergency medical kits and provisions to last us four days.

Just as the sun began to rise above a distant range of hills that we aimed to cross later that day, our car came to a halt in front of a stream. Because of the rainy reason, it carried more water than usual. It was time to disembark and start walking, or “footing,” as South Sudanese tend to call it.

We took off our shoes and waded through the stream’s chilly waters. This was the first of a many rivers we’d have to cross along the way, either on foot or in small flimsy canoes dug out from tree trunks. Each time, we dreaded the idea of falling in with our camera gear.

The first part of our journey in northern Uganda felt very much like a hike through a national park. Passing beautiful landscapes and idyllic farming villages, one could almost forget we were headed into a war zone — but we were about to get a reality check.

We had just crossed into South Sudan when out of nowhere, two dozen armed men popped out of the tall grass and surrounded us at gunpoint.

“Stop! Who are you and where are you going?” a soldier called out in Juba Arabic from his hideout no more than 20 yards away, pointing his AK47 at us. Another one next to him had a rocket-propelled grenade propped on his shoulder, also unequivocally aiming it in our direction.

Instinctively, we threw our hands in the air and exchanged a baffled glance. Had we accidentally bumped into government soldiers? Or perhaps we had come onto the “wrong” rebels? Abucha’s group, called the Sudan People’s Liberation Army In Opposition, is the biggest but not the only armed group in Equatoria, an area rife with rival militia and bandits who exploit the security vacuum left by war.

To our relief, and only after Abucha answered a series of questions, this routine security check quickly gave way to a warm welcome. The platoon would be our escort for the next four days as we trekked to their base and to Loa, Abucha’s hometown.

Keeping up with the rebels was no easy task. Given the country’s pervasive lack of basic infrastructure, South Sudanese grow up walking for dozens of miles just to go about their daily lives. For sedentary Westerners, keeping the target pace of “two meters per second” (around five miles an hour) proved challenging amid 90-degree temperatures, all while filming and plowing our way through dense, itchy elephant grass.

The upside of the cumbersome terrain was that it kept us safe. During our four-day trip, we didn’t cross a single road, instead walking along a dizzying network of narrow bush paths the rebels seemed to know like the backs of their hands. An unwanted encounter with government troops, who tended to stick to roads and move around in vehicles as opposed to on foot, was highly unlikely.

The closest we got to government-controlled area was a visit to Loa, located just two kilometers away from a main road frequently patrolled by government soldiers. We couldn’t stay long, but the hour we spent on the ground offered us a glimpse into what villages must look like in many parts of Equatoria: burned mud huts, looted schools and clinics, fallow fields and – most strikingly – no civilians.

The war has had a devastating impact on South Sudanese communities like the one in Loa, but much of it has remained out of the limelight of international media. Our four-day venture into rebel-held South Sudan offered us a rare opportunity to report ground truths, and we are thankful for that.

The post Column: Why reporting from South Sudan is so difficult — and critically needed appeared first on PBS NewsHour.




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Tillerson: ‘Heartbreaking’ reports of suffering in Myanmar

Secretary of State Rex Tillerson speaks at the Center for Strategic and International Studies on Wednesday.

WASHINGTON — Secretary of State Rex Tillerson is condemning reported atrocities committed against Rohingya Muslims in Myanmar, and he says those responsible — perhaps the country’s military — will be held accountable.

Tillerson says accounts of the suffering of the Rohingya are “heartbreaking” — and that if those reports are true, then “someone is going to be held to account for that.”

Tillerson — who’s set to visit South Asia next week — is urging the Myanmar government to improve humanitarian access to the population in western Rakhine state.

Amnesty International has accused Myanmar’s security forces of killing hundreds of men, women and children during a systematic campaign to expel the Rohingya. More than 580,000 refugees have fled to neighboring Bangladesh since late August.

“We really hold the military leadership accountable for what’s happening,” Tillerson said at the Center for Strategic and International Studies, a Washington think tank. “What’s most important to us is that the world can’t just stand idly by and be witness to the atrocities that are being reported in that area.”

He also called Wednesday for the U.S. and India to expand strategic ties. He pointedly criticized China, which he accused of challenging international norms needed for global stability.

He said the world needed the U.S. and India to have a strong partnership. The two nations share goals of security, free navigation, free trade and fighting terrorism in the Indo-Pacific, and serve as “the eastern and western beacons” for an international rules-based order which is increasingly under strain, he said.

Both India and China had benefited from that order, but Tillerson said India had done so while respecting rules and norms, while China had “at times” undermined them. To make his point, he alluded to China’s island building and expansive territorial claims in seas where Beijing has long-running disputes with Southeast Asian neighbors.

“China’s provocative actions in the South China Sea directly challenge the international law and norms that the United States and India both stand for,” Tillerson said in an address at the Center for Strategic and International Studies, a Washington think tank.

He added that the U.S. seeks constructive relations with China but “won’t shrink” from the challenges it poses when it “subverts the sovereignty of neighboring countries, and disadvantages the U.S. and our friends.”

U.S.-India relations have generally prospered in the past decade, in part because of their shared concerns about the rise of China. While President Donald Trump has looked to deepen cooperation with China on addressing the nuclear threat from North Korea, he’s also sought a closer relationship with India, which shares U.S. worries on Islamic extremism.

“In this period of uncertainty and angst, India needs a reliable partner on the world stage. I want to make clear: with our shared values and vision for global stability, peace and prosperity, the United States is that partner,” Tillerson said.

Tillerson said the U.S. wants to help improve India’s military capabilities, and also improve security cooperation among the region’s major democracies, which included Japan and Australia.

Tillerson said the U.S. and India were leading regional efforts on counterterrorism. He called for India’s archrival Pakistan “to take decisive action against terrorist groups based within their own borders that threaten its own people and the broader region.”

The post Tillerson: ‘Heartbreaking’ reports of suffering in Myanmar appeared first on PBS NewsHour.




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'Systematic racism' in social work in Scotland to be addressed in review after report

A national review of social work in Scotland has been launched in a bid to address ‘systemic racism’ within the sector.




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Scottish airport chief 'thrilled' as airline giant launches first advanced aircraft

The plane is hailed as 'one of the most advanced aircraft available on the market'




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EA Sports FC 25 Debuts in 1st on the Canadian Charts

EA Sports FC 25 has debuted in first place on the Canadian charts for September 2024, according to data from Circana (formerly The NPD Group) reported by the Entertainment Software Association of Canada (ESA).

There were four other new releases in the top 10 with NHL 25 debuting in second place, The Legend of Zelda: Echoes of Wisdom in third place, Astro Bot in fourth place, and NBA 2K25 in 10th place.

Star Wars: Outlaws is in fifth place, Hogwarts Legacy is in sixth place, and Madden NFL 25 is in seventh place. God of War: Ragnarök is in eighth place following the release of the PC version and Elden Ring is in ninth place.

Top 10 best-selling games in Canada:

  1. EA Sports FC 25 - NEW
  2. NHL 25 - NEW
  3. The Legend of Zelda: Echoes of Wisdom* - NEW
  4. Astro Bot - NEW
  5. Star Wars: Outlaws
  6. Hogwarts Legacy
  7. Madden NFL 25
  8. God of War: Ragnarök
  9. Elden Ring
  10. NBA 2K25* - NEW

*Digital sales not included

A life-long and avid gamer, William D'Angelo was first introduced to VGChartz in 2007. After years of supporting the site, he was brought on in 2010 as a junior analyst, working his way up to lead analyst in 2012 and taking over the hardware estimates in 2017. He has expanded his involvement in the gaming community by producing content on his own YouTube channel and Twitch channel. You can contact the author on Twitter @TrunksWD.

Full Article - https://www.vgchartz.com/article/463027/ea-sports-fc-25-debuts-in-1st-on-the-canadian-charts/




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Trump Calls Jan. 6, the Day His Supporters Led a Failed Insurrection, ‘A Day of Love’

Marco Bello/Reuters

Former President Donald Trump said Wednesday that Jan. 6, 2021— the day his supporters occupied Congress in a failed insurrection to try to stop lawmakers from certifying Joe Biden’s election victory—was a “day of love.”

Trump made the baffling claim during a televised election town hall hosted by Univision.

Ramiro González, a construction worker from Tampa, told the meeting he deregistered as a Republican because he found Trump’s “inaction” during both Jan. 6 and the COVID-19 pandemic “disturbing.” He asked Trump to square his controversial behavior during the attack on the U.S. Capitol—and the fact that many of his own former administration officials don’t support him any longer—with why he should be re-elected.

Read more at The Daily Beast.




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Respawn have killed Apex Legends' Steam Deck support in the name of anti-cheat

The Steam Deck is something of a talisman for gaming on Linux, its popularity and penguin-powered SteamOS having almost singlehandedly dragged it past MacOS as the second-most-used operating system among Steam users. Sadly, this also means the Valve handheld is the primary casualty when developers decide to stop bothering with Linux support, as Respawn Entertainment have decided to do for Apex Legends.

Read more




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Dragon Age: The Veilguard won't get expansions, reports say, as BioWare move to the next Mass Effect

BioWare currently has no plans for Dragon Age: The Veilguard expansions, according to reports. Instead the studio will support the fantasy RPG with smaller updates and otherwise turn their full attention towards Mass Effect 5.

Read more




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Five of the most important International Space Station experiments

From artificial retinas to ageing mice, here are five of the most promising results from research performed on the ISS – and what they might mean for humans on Earth and in space




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Quantum computers teleport and store energy harvested from empty space

A quantum computing protocol makes it possible to extract energy from seemingly empty space, teleport it to a new location, then store it for later use




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American Sports Story: Aaron Hernandez Finale Recap: Absolute Freedom

The finale doesn’t look to provide a definitive answer to what drove Aaron’s actions, much to the show’s credit.




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Germany's Harsh Reckoning Is Also an Opportunity




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Demand Senators Publicly Support a Leader Who's Pro-Trump

Hours after Donald Trump wins the most conclusive mandate in 40 years, Mitch McConnell engineers a coup against his agenda by calling early leadership elections in the senate.




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The Case for Mass Deportations

It's hard to imagine opposing Trump's proposal. Who would want to help murderers and drug dealers who entered the country illegally remain in the United States?




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Inside the report that reveals the extent of DEI spending in HHS

A new report by OpenTheBooks reveals that the Health and Human Services Department (HHS) employs 294 people in diversity-focused positions, with 182 of them earning six-figure salaries.




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Report: NFL intentionally delayed fine for 49ers' Nick Bosa until after election

According to a report Tuesday, the league deliberately decided not to impose an immediate fine on San Francisco 49ers defensive end Nick Bosa for wearing a "Make America Great Again" hat during a postgame television interview.




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'Bring on Lampard and Morris!' - Chelsea fans react to reports of Gianfranco Zola exit

The Italian is reportedly set to leave Stamford Bridge at the end of his contract..





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Great British summer of sport - your guide to how each event is ready for return of crowds