Title: Exercise Plus Computer Time May Boost Seniors' Brains
Category: Health News
Created: 5/1/2012 6:05:00 PM
Last Editorial Review: 5/2/2012 12:00:00 AM

Title: Health Tip: Make TV Time Exercise Time
Category: Health News
Created: 5/4/2012 8:05:00 AM
Last Editorial Review: 5/4/2012 12:00:00 AM

Title: Exercise May Lower Older Women's Risk for Kidney Stones
Category: Health News
Created: 5/3/2013 12:35:00 PM
Last Editorial Review: 5/3/2013 12:00:00 AM

Title: Exercise and Vitamin D: A Heart-Healthy Combo
Category: Health News
Created: 5/1/2017 12:00:00 AM
Last Editorial Review: 5/1/2017 12:00:00 AM

Title: Get Out There and Exercise
Category: Health News
Created: 5/1/2017 12:00:00 AM
Last Editorial Review: 5/1/2017 12:00:00 AM

Title: Health Tip: Getting Enough Hard Exercise
Category: Health News
Created: 5/2/2017 12:00:00 AM
Last Editorial Review: 5/2/2017 12:00:00 AM

Title: Low-Dose Aspirin May Lower Risk for Common Breast Cancer by 20 Percent
Category: Health News
Created: 5/1/2017 12:00:00 AM
Last Editorial Review: 5/2/2017 12:00:00 AM

Title: Rock Climbing Goes Mainstream for Exercise Buffs
Category: Health News
Created: 5/1/2018 12:00:00 AM
Last Editorial Review: 5/1/2018 12:00:00 AM

Title: U.S. Motorcycle Deaths Dropped 6 Percent Last Year
Category: Health News
Created: 5/4/2018 12:00:00 AM
Last Editorial Review: 5/4/2018 12:00:00 AM

Title: Tailoring Exercise to Your Age
Category: Health News
Created: 4/29/2019 12:00:00 AM
Last Editorial Review: 4/29/2019 12:00:00 AM

Title: Many Women With Heart Disease Falling Short on Exercise
Category: Health News
Created: 4/26/2019 12:00:00 AM
Last Editorial Review: 4/29/2019 12:00:00 AM

Title: Morning Exercise Kick-Starts Seniors' Brains
Category: Health News
Created: 5/2/2019 12:00:00 AM
Last Editorial Review: 5/2/2019 12:00:00 AM

Title: Eylea (aflibercept)
Category: Medications
Created: 4/25/2020 12:00:00 AM
Last Editorial Review: 4/25/2020 12:00:00 AM

Title: AHA News: Most of the Nation's Teens Aren't Getting Enough Exercise
Category: Health News
Created: 4/9/2020 12:00:00 AM
Last Editorial Review: 4/10/2020 12:00:00 AM

Title: U.S. Jobless Rate at Nearly 15 Percent as Coronavirus Cases Top 1.2 Million
Category: Health News
Created: 5/8/2020 12:00:00 AM
Last Editorial Review: 5/8/2020 12:00:00 AM

Title: Intense Exercise Can Trigger Heart Trouble in the Unprepared
Category: Health News
Created: 3/2/2020 12:00:00 AM
Last Editorial Review: 3/3/2020 12:00:00 AM

Few studies have been published on thesis completion experiences of master’s degree students. However, for doctoral students, dissertation completion has been found to be dependent on individual, relational, and institutional factors. The aim of this study was to examine dental hygienists’ perceptions of their experiences completing a thesis as a requirement for an advanced degree. A qualitative phenomenological research design was used utilizing virtual focus groups with a national purposive sample of dental hygienists (n=25) who had graduated from a degree program in which a thesis was a requirement for the degree. Data analysis used an inductive approach to identify themes using Liechty et al.’s framework of individual, relational, and institutional factors impacting completion of a dissertation. Liechty et al.’s framework is based on Vygotsky’s sociocultural theory of learning. In the results, individual factors identified included family/work responsibilities, lack of understanding of the thesis process, time management, health issues, and reaching personal and professional goals. Relational factors focused primarily on positive and negative experiences with the thesis advisor/committee and support from expert peers/family. Institutional factors included the thesis structure, financial concerns, and challenges in recruiting research participants. This study found many factors influencing the thesis experience that may help guide the process in graduate degree programs. In addition, the findings suggest a need to provide mentoring and support for thesis advisors and committee members to more effectively guide students through the thesis process. Effective modifications of these may improve retention of students and facilitate timely completion of thesis research.

ABSTRACT

Synthesis and cleavage of the cell wall polymer peptidoglycan (PG) are carefully orchestrated processes and are essential for the growth and survival of bacteria. Yet, the function and importance of many enzymes that act on PG in Mycobacterium tuberculosis remain to be elucidated. We demonstrate that the activity of the N-acetylmuramyl-l-alanine amidase Ami1 is dispensable for cell division in M. tuberculosis in vitro yet contributes to the bacterium’s ability to persist during chronic infection in mice. Furthermore, the d,l-endopeptidase RipA, a predicted essential enzyme, is dispensable for the viability of M. tuberculosis but required for efficient cell division in vitro and in vivo. Depletion of RipA sensitizes M. tuberculosis to rifampin and to cell envelope-targeting antibiotics. Ami1 helps sustain residual cell division in cells lacking RipA, but the partial redundancy provided by Ami1 is not sufficient during infection, as depletion of RipA prevents M. tuberculosis from replicating in macrophages and leads to dramatic killing of the bacteria in mice. Notably, RipA is essential for persistence of M. tuberculosis in mice, suggesting that cell division is required during chronic mouse infection. Despite the multiplicity of enzymes acting on PG with redundant functions, we have identified two PG hydrolases that are important for M. tuberculosis to replicate and persist in the host.

IMPORTANCE Tuberculosis (TB) is a major global heath burden, with 1.6 million people succumbing to the disease every year. The search for new drugs to improve the current chemotherapeutic regimen is crucial to reducing this global health burden. The cell wall polymer peptidoglycan (PG) has emerged as a very successful drug target in bacterial pathogens, as many currently used antibiotics target the synthesis of this macromolecule. However, the multitude of genes encoding PG-synthesizing and PG-modifying enzymes with apparent redundant functions has hindered the identification of novel drug targets in PG synthesis in Mycobacterium tuberculosis. Here, we demonstrate that two PG-cleaving enzymes are important for virulence of M. tuberculosis. In particular, the d,l-endopeptidase RipA represents a potentially attractive drug target, as its depletion results in the clearance of M. tuberculosis from the host and renders the bacteria hypersusceptible to rifampin, a frontline TB drug, and to several cell wall-targeting antibiotics.

ABSTRACT

The synergy between Mycobacterium tuberculosis and human immunodeficiency virus-1 (HIV-1) interferes with therapy and facilitates the pathogenesis of both human pathogens. Fundamental mechanisms by which M. tuberculosis exacerbates HIV-1 infection are not clear. Here, we show that exosomes secreted by macrophages infected with M. tuberculosis, including drug-resistant clinical strains, reactivated HIV-1 by inducing oxidative stress. Mechanistically, M. tuberculosis-specific exosomes realigned mitochondrial and nonmitochondrial oxygen consumption rates (OCR) and modulated the expression of host genes mediating oxidative stress response, inflammation, and HIV-1 transactivation. Proteomics analyses revealed the enrichment of several host factors (e.g., HIF-1α, galectins, and Hsp90) known to promote HIV-1 reactivation in M. tuberculosis-specific exosomes. Treatment with a known antioxidant—N-acetyl cysteine (NAC)—or with inhibitors of host factors—galectins and Hsp90—attenuated HIV-1 reactivation by M. tuberculosis-specific exosomes. Our findings uncover new paradigms for understanding the redox and bioenergetics bases of HIV-M. tuberculosis coinfection, which will enable the design of effective therapeutic strategies.

IMPORTANCE Globally, individuals coinfected with the AIDS virus (HIV-1) and with M. tuberculosis (causative agent of tuberculosis [TB]) pose major obstacles in the clinical management of both diseases. At the heart of this issue is the apparent synergy between the two human pathogens. On the one hand, mechanisms induced by HIV-1 for reactivation of TB in AIDS patients are well characterized. On the other hand, while clinical findings clearly identified TB as a risk factor for HIV-1 reactivation and associated mortality, basic mechanisms by which M. tuberculosis exacerbates HIV-1 replication and infection remain poorly characterized. The significance of our research is in identifying the role of fundamental mechanisms such as redox and energy metabolism in catalyzing HIV-M. tuberculosis synergy. The quantification of redox and respiratory parameters affected by M. tuberculosis in stimulating HIV-1 will greatly enhance our understanding of HIV-M. tuberculosis coinfection, leading to a wider impact on the biomedical research community and creating new translational opportunities.

ABSTRACT

Mobile elements—plasmids and phages—are important components of microbial function and evolution via traits that they encode and their capacity to shuttle genetic material between species. We here report the unusually rich array of mobile elements within the genome of Arsenophonus nasoniae, the son-killer symbiont of the parasitic wasp Nasonia vitripennis. This microbe’s genome has the highest prophage complement reported to date, with over 50 genomic regions that represent either intact or degraded phage material. Moreover, the genome is predicted to include 17 extrachromosomal genetic elements, which carry many genes predicted to be important at the microbe-host interface, derived from a diverse assemblage of insect-associated gammaproteobacteria. In our system, this diversity was previously masked by repetitive mobile elements that broke the assembly derived from short reads. These findings suggest that other complex bacterial genomes will be revealed in the era of long-read sequencing.

IMPORTANCE The biology of many bacteria is critically dependent on genes carried on plasmid and phage mobile elements. These elements shuttle between microbial species, thus providing an important source of biological innovation across taxa. It has recently been recognized that mobile elements are also important in symbiotic bacteria, which form long-lasting interactions with their host. In this study, we report a bacterial symbiont genome that carries a highly complex array of these elements. Arsenophonus nasoniae is the son-killer microbe of the parasitic wasp Nasonia vitripennis and exists with the wasp throughout its life cycle. We completed its genome with the aid of recently developed long-read technology. This assembly contained over 50 chromosomal regions of phage origin and 17 extrachromosomal elements within the genome, encoding many important traits at the host-microbe interface. Thus, the biology of this symbiont is enabled by a complex array of mobile elements.

ABSTRACT

RepA is a bacterial protein that builds intracellular amyloid oligomers acting as inhibitory complexes of plasmid DNA replication. When carrying a mutation enhancing its amyloidogenesis (A31V), the N-terminal domain (WH1) generates cytosolic amyloid particles that are inheritable within a bacterial lineage. Such amyloids trigger in bacteria a lethal cascade reminiscent of mitochondrial impairment in human cells affected by neurodegeneration. To fulfill all the criteria to qualify as a prion-like protein, horizontal (intercellular) transmissibility remains to be demonstrated for RepA-WH1. Since this is experimentally intractable in bacteria, here we transiently expressed in a murine neuroblastoma cell line the soluble, barely cytotoxic RepA-WH1 wild type [RepA-WH1(WT)] and assayed its response to exposure to in vitro-assembled RepA-WH1(A31V) amyloid fibers. In parallel, murine cells releasing RepA-WH1(A31V) aggregates were cocultured with human neuroblastoma cells expressing RepA-WH1(WT). Both the assembled fibers and donor-derived RepA-WH1(A31V) aggregates induced, in the cytosol of recipient cells, the formation of cytotoxic amyloid particles. Mass spectrometry analyses of the proteomes of both types of injured cells pointed to alterations in mitochondria, protein quality triage, signaling, and intracellular traffic. Thus, a synthetic prion-like protein can be propagated to, and become cytotoxic to, cells of organisms placed at such distant branches of the tree of life as bacteria and mammalia, suggesting that mechanisms of protein aggregate spreading and toxicity follow default pathways.

IMPORTANCE Proteotoxic amyloid seeds can be transmitted between mammalian cells, arguing that the intercellular exchange of prion-like protein aggregates can be a common phenomenon. RepA-WH1 is derived from a bacterial intracellular functional amyloid protein, engineered to become cytotoxic in Escherichia coli. Here, we have studied if such bacterial aggregates can also be transmitted to, and become cytotoxic to, mammalian cells. We demonstrate that RepA-WH1 is capable of entering naive cells, thereby inducing the cytotoxic aggregation of a soluble RepA-WH1 variant expressed in the cytosol, following the same trend that had been described in bacteria. These findings highlight the universality of one of the central principles underlying prion biology: No matter the biological origin of a given prion-like protein, it can be transmitted to a phylogenetically unrelated recipient cell, provided that the latter expresses a soluble protein onto which the incoming protein can readily template its amyloid conformation.

Despite the ecological relevance of diatoms, many aspects of their photosynthetic machinery remain poorly understood. Diatoms differ from the green lineage of oxygenic organisms by their photosynthetic pigments and light-harvesting complex (Lhc) proteins, the latter of which are also called fucoxanthin-chlorophyll proteins (FCP). These are composed of three groups of proteins: Lhcf as the main group, Lhcr that are PSI associated, and Lhcx that are involved in photoprotection. The FCP complexes are assembled in trimers and higher oligomers. Several studies have investigated the biochemical properties of purified FCP complexes, but limited knowledge is available about their interaction with the photosystem cores. In this study, isolation of stable supercomplexes from the centric diatom Thalassiosira pseudonana was achieved. To preserve in vivo structure, the separation of thylakoid complexes was performed by native PAGE and sucrose density centrifugation. Different subpopulations of PSI and PSII supercomplexes were isolated and their subunits identified. Analysis of Lhc antenna composition identified Lhc(s) specific for either PSI (Lhcr 1, 3, 4, 7, 10–14, and Lhcf10) or PSII (Lhcf 1–7, 11, and Lhcr2). Lhcx6_1 was reproducibly found in PSII supercomplexes, whereas its association with PSI was unclear. No evidence was found for the interaction between photosystems and higher oligomeric FCPs, comprising Lhcf8 as the main component. Although the subunit composition of the PSII supercomplexes in comparison with that of the trimeric FCP complexes indicated a close mutual association, the higher oligomeric pool is only weakly associated with the photosystems, albeit its abundance in the thylakoid membrane.

For cell entry, vaccinia virus requires fusion with the host membrane via a viral fusion complex of 11 proteins, but the mechanism remains unclear. It was shown previously that the viral proteins A56 and K2 are expressed on infected cells to prevent superinfection by extracellular vaccinia virus through binding to two components of the viral fusion complex (G9 and A16), thereby inhibiting membrane fusion. To investigate how the A56/K2 complex inhibits membrane fusion, we performed experimental evolutionary analyses by repeatedly passaging vaccinia virus in HeLa cells overexpressing the A56 and K2 proteins to isolate adaptive mutant viruses. Genome sequencing of adaptive mutants revealed that they had accumulated a unique G9R open reading frame (ORF) mutation, resulting in a single His44Tyr amino acid change. We engineered a recombinant vaccinia virus to express the G9^H44Y mutant protein, and it readily infected HeLa-A56/K2 cells. Moreover, similar to the A56 virus, the G9^H44Y mutant virus on HeLa cells had a cell fusion phenotype, indicating that G9^H44Y-mediated membrane fusion was less prone to inhibition by A56/K2. Coimmunoprecipitation experiments demonstrated that the G9^H44Y protein bound to A56/K2 at neutral pH, suggesting that the H44Y mutation did not eliminate the binding of G9 to A56/K2. Interestingly, upon acid treatment to inactivate A56/K2-mediated fusion inhibition, the G9^H44Y mutant virus induced robust cell-cell fusion at pH 6, unlike the pH 4.7 required for control and revertant vaccinia viruses. Thus, A56/K2 fusion suppression mainly targets the G9 protein. Moreover, the G9^H44Y mutant protein escapes A56/K2-mediated membrane fusion inhibition most likely because it mimics an acid-induced intermediate conformation more prone to membrane fusion.

IMPORTANCE It remains unclear how the multiprotein entry fusion complex of vaccinia virus mediates membrane fusion. Moreover, vaccinia virus contains fusion suppressor proteins to prevent the aberrant activation of this multiprotein complex. Here, we used experimental evolution to identify adaptive mutant viruses that overcome membrane fusion inhibition mediated by the A56/K2 protein complex. We show that the H44Y mutation of the G9 protein is sufficient to overcome A56/K2-mediated membrane fusion inhibition. Treatment of virus-infected cells at different pHs indicated that the H44Y mutation lowers the threshold of fusion inhibition by A56/K2. Our study provides evidence that A56/K2 inhibits the viral fusion complex via the latter’s G9 subcomponent. Although the G9^H44Y mutant protein still binds to A56/K2 at neutral pH, it is less dependent on low pH for fusion activation, implying that it may adopt a subtle conformational change that mimics a structural intermediate induced by low pH.

The entry/fusion complex (EFC) consists of 11 conserved proteins embedded in the membrane envelope of mature poxvirus particles. Poxviruses also encode proteins that localize in cell membranes and negatively regulate superinfection and syncytium formation. The vaccinia virus (VACV) A56/K2 fusion regulatory complex associates with the G9/A16 EFC subcomplex, but functional support for the importance of this interaction was lacking. Here, we describe serially passaging VACV in nonpermissive cells expressing A56/K2 as an unbiased approach to isolate and analyze escape mutants. Viruses forming large plaques in A56/K2 cells increased in successive rounds of infection, indicating the occurrence and enrichment of adaptive mutations. Sequencing of genomes of passaged and cloned viruses revealed mutations near the N terminus of the G9 open reading frame but none in A16 or other genes. The most frequent mutation was His to Tyr at amino acid 44; additional escape mutants had a His-to-Arg mutation at amino acid 44 or a duplication of amino acids 26 to 39. An adaptive Tyr-to-Cys substitution at amino acid 42 was discovered using error-prone PCR to generate additional mutations. Myristoylation of G9 was unaffected by the near-N-terminal mutations. The roles of the G9 mutations in enhancing plaque size were validated by homologous recombination. The mutants exhibited enhanced entry and spread in A56/K2 cells and induced syncytia at neutral pH in HeLa cells despite the expression of A56/K2. The data suggest that the mutations perturb the interaction of G9 with A56/K2, although some association was still detected in detergent-treated infected cell lysates.

IMPORTANCE The entry of enveloped viruses is achieved by the fusion of viral and cellular membranes, a critical step in infection that determines host range and provides targets for vaccines and therapeutics. Poxviruses encode an exceptionally large number of proteins comprising the entry/fusion complex (EFC), which enables infection of diverse cells. Vaccinia virus (VACV), the prototype member of the poxvirus family, also encodes the fusion regulatory proteins A56 and K2, which are displayed on the plasma membrane and may be beneficial by preventing reinfection and cell-cell fusion. Previous studies showed that A56/K2 interacts with the G9/A16 EFC subcomplex in detergent-treated cell extracts. Functional evidence for the importance of this interaction was obtained by serially passaging wild-type VACV in cells that are nonpermissive because of A56/K2 expression. VACV mutants with amino acid substitutions or duplications near the N terminus of G9 were enriched because of their ability to overcome the block to entry imposed by A56/K2.

Synesthesia is a neurologic trait in which specific inducers, such as sounds, automatically elicit additional idiosyncratic percepts, such as color (thus “colored hearing”). One explanation for this trait—and the one tested here—is that synesthesia results from unusually weak pruning of cortical synaptic hyperconnectivity during early perceptual development. We tested the...

High magnetic fields have revealed a surprisingly small Fermi surface in underdoped cuprates, possibly resulting from Fermi-surface reconstruction due to an order parameter that breaks translational symmetry of the crystal lattice. A crucial issue concerns the doping extent of such a state and its relationship to the principal pseudogap and...

Purpose:

To identify specific actions and characteristics of health care providers (HCPs) in the United States and Canada that influenced patients with type 2 diabetes who were initially reluctant to begin insulin.

Ricardo Benini, Leandro A. Oliveira, Lucas Gomes-de-Souza, Bruno Rodrigues, and Carlos C. Crestani

This study evaluated the effect of exposure to either a chronic variable stress (CVS) protocol or social isolation, as well as treadmill exercise training, in the habituation of the cardiovascular response upon repeated exposure to restraint stress in rats. The habituation of the corticosterone response to repeated restraint stress was also evaluated. For this, animals were subjected to either acute or 10 daily sessions of 60 min of restraint stress. CVS and social isolation protocols lasted for 10 consecutive days, whereas treadmill training was performed for 1 h per day, 5 days per week for 8 weeks. We observed that the increase in serum corticosterone was reduced during both the stress and the recovery period of the 10th session of restraint. Habituation of the cardiovascular response was identified in terms of a faster return of heart rate to baseline values during the recovery period of the 10th session of restraint. The increase in blood pressure and the decrease in tail skin temperature were similar at the 1st and 10th session of restraint. Exposure to CVS, social isolation or treadmill exercise training inhibited the habituation of the restraint-evoked tachycardia. Additionally, CVS increased the blood pressure response at the 10th session of restraint, whereas social isolation enhanced both the tachycardia during the first session and the drop in skin temperature at the 10th session of restraint. Taken together, these findings provide new evidence that pathologies evoked by stress might be related to impairment in the habituation process to homotypic stressors.

BACKGROUND:Patients with cystic fibrosis develop decreased exercise capacity. However, the main factors responsible for this decline are still unclear. Thus, the objective of this study was to evaluate the factors influencing exercise capacity assessed with the modified shuttle test (MST) in individuals with cystic fibrosis.METHODS:A cross-sectional study was carried out in subjects with a diagnosis of cystic fibrosis who were 6–26 y old and were regularly monitored at 2 cystic fibrosis reference centers in Brazil. Individuals who were unable to perform the tests or who exhibited hemodynamic instability and exacerbation of respiratory symptoms were excluded. Anthropometric, clinical, and genotype data were collected. In addition, lung function and exercise capacity were evaluated with the MST.RESULTS:73 subjects (mean age 12.2 ± 4.9 y and FEV1 76.8 ± 23.3%) were included. The mean distance achieved in the MST was 765 ± 258 m (71.6% of predicted). The distance achieved on the MST correlated significantly with age (r = 0.49, P < .001), body mass index (r = 0.41, P < .001), resting heart rate (r = −0.51, P < .001), and FEV1 (r = 0.24, P = .042). Subjects with FEV1 > 67% of predicted (P = .02) and those with resting heart rate < 100 beats/min (P = .01) had a greater exercise capacity. Resting heart rate, age, and FEV1 (%) were found as significant variables to explain the distance achieved on the MST (R2 = 0.48, standard error = 191.0 m).CONCLUSIONS:The main determinants of exercise capacity assessed with the MST in individuals with cystic fibrosis were resting heart rate, age, and lung function.

3-Mercaptopyruvate sulfur transferase (MPST) catalyzes the desulfuration of 3-mercaptopyruvate (3-MP) and transfers sulfane sulfur from an enzyme-bound persulfide intermediate to thiophilic acceptors such as thioredoxin and cysteine. Hydrogen sulfide (H2S), a signaling molecule implicated in many physiological processes, can be released from the persulfide product of the MPST reaction. Two splice variants of MPST, differing by 20 amino acids at the N terminus, give rise to the cytosolic MPST1 and mitochondrial MPST2 isoforms. Here, we characterized the poorly-studied MPST1 variant and demonstrated that substitutions in its Ser–His–Asp triad, proposed to serve a general acid–base role, minimally affect catalytic activity. We estimated the 3-MP concentration in murine liver, kidney, and brain tissues, finding that it ranges from 0.4 μmol·kg−1 in brain to 1.4 μmol·kg−1 in kidney. We also show that N-acetylcysteine, a widely-used antioxidant, is a poor substrate for MPST and is unlikely to function as a thiophilic acceptor. Thioredoxin exhibits substrate inhibition, increasing the KM for 3-MP ∼15-fold compared with other sulfur acceptors. Kinetic simulations at physiologically-relevant substrate concentrations predicted that the proportion of sulfur transfer to thioredoxin increases ∼3.5-fold as its concentration decreases from 10 to 1 μm, whereas the total MPST reaction rate increases ∼7-fold. The simulations also predicted that cysteine is a quantitatively-significant sulfane sulfur acceptor, revealing MPST's potential to generate low-molecular-weight persulfides. We conclude that the MPST1 and MPST2 isoforms are kinetically indistinguishable and that thioredoxin modulates the MPST-catalyzed reaction in a physiologically-relevant concentration range.

Triple-negative breast cancer (TNBC) is characterized by its aggressive biology, early metastatic spread, and poor survival outcomes. TNBC lacks expression of the targetable receptors found in other breast cancer subtypes, mandating use of cytotoxic chemotherapy. However, resistance to chemotherapy is a significant problem, encountered in about two-thirds of TNBC patients, and new strategies are needed to mitigate resistance. In this issue of the Journal of Biological Chemistry, Geck et al. report that TNBC cells are highly sensitive to inhibition of the de novo polyamine synthesis pathway and that inhibition of this pathway sensitizes cells to TNBC-relevant chemotherapy, uncovering new opportunities for addressing chemoresistance.

Allostery exploits the conformational dynamics of enzymes by triggering a shift in population ensembles toward functionally distinct conformational or dynamic states. Allostery extensively regulates the activities of key enzymes within biosynthetic pathways to meet metabolic demand for their end products. Here, we have examined a critical enzyme, 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase (DAH7PS), at the gateway to aromatic amino acid biosynthesis in Mycobacterium tuberculosis, which shows extremely complex dynamic allostery: three distinct aromatic amino acids jointly communicate occupancy to the active site via subtle changes in dynamics, enabling exquisite fine-tuning of delivery of these essential metabolites. Furthermore, this allosteric mechanism is co-opted by pathway branchpoint enzyme chorismate mutase upon complex formation. In this study, using statistical coupling analysis, site-directed mutagenesis, isothermal calorimetry, small-angle X-ray scattering, and X-ray crystallography analyses, we have pinpointed a critical node within the complex dynamic communication network responsible for this sophisticated allosteric machinery. Through a facile Gly to Pro substitution, we have altered backbone dynamics, completely severing the allosteric signal yet remarkably, generating a nonallosteric enzyme that retains full catalytic activity. We also identified a second residue of prime importance to the inter-enzyme communication with chorismate mutase. Our results reveal that highly complex dynamic allostery is surprisingly vulnerable and provide further insights into the intimate link between catalysis and allostery.

Bovine tuberculosis (TB), caused by Mycobacterium bovis, remains an important zoonotic disease posing a serious threat to livestock and wildlife. The current TB tests relying on cell-mediated and humoral immune responses in cattle have performance limitations. To identify new serodiagnostic markers of bovine TB, we screened a panel of 101 recombinant proteins, including 10 polyepitope fusions, by a multiantigen print immunoassay (MAPIA) with well-characterized serum samples serially collected from cattle with experimental or naturally acquired M. bovis infection. A novel set of 12 seroreactive antigens was established. Evaluation of selected proteins in the dual-path platform (DPP) assay showed that the highest diagnostic accuracy (~95%) was achieved with a cocktail of five best-performing antigens, thus demonstrating the potential for development of an improved and more practical serodiagnostic test for bovine TB.

As yet, very few vaccine candidates with activity in animals against Mycobacterium tuberculosis infection have been tested as therapeutic postexposure vaccines. We recently described two pools of mycobacterial proteins with this activity, and here we describe further studies in which four of these proteins (Rv1738, Rv2032, Rv3130, and Rv3841) were generated as a fusion polypeptide and then delivered in a novel yeast-based platform (Tarmogen) which itself has immunostimulatory properties, including activation of Toll-like receptors. This platform can deliver antigens into both the class I and class II antigen presentation pathways and stimulate strong Th1 and Th17 responses. In mice this fusion vaccine, designated GI-19007, was immunogenic and elicited strong gamma interferon (IFN-) and interleukin-17 (IL-17) responses; despite this, they displayed minimal prophylactic activity in mice that were subsequently infected with a virulent clinical strain. In contrast, in a therapeutic model in the guinea pig, GI-19007 significantly reduced the lung bacterial load and reduced lung pathology, particularly in terms of secondary lesion development, while significantly improving survival in one-third of these animals. In further studies in which guinea pigs were vaccinated with BCG before challenge, therapeutic vaccination with GI-19007 initially improved survival versus that of animals given BCG alone, although this protective effect was gradually lost at around 400 days after challenge. Given its apparent ability to substantially limit bacterial dissemination within and from the lungs, GI-19007 potentially can be used to limit lung damage as well as facilitating chemotherapeutic regimens in infected individuals.

The emergence of drug resistance is a major obstacle for the success of targeted therapy in melanoma. Additionally, conventional chemotherapy has not been effective as drug-resistant cells escape lethal DNA damage effects by inducing growth arrest commonly referred to as cellular dormancy. We present a therapeutic strategy termed "targeted chemotherapy" by depleting protein phosphatase 2A (PP2A) or its inhibition using a small molecule inhibitor (1,10-phenanthroline-5,6-dione [phendione]) in drug-resistant melanoma. Targeted chemotherapy induces the DNA damage response without causing DNA breaks or allowing cellular dormancy. Phendione treatment reduces tumor growth of BRAF^V600E-driven melanoma patient-derived xenografts (PDX) and diminishes growth of NRAS^Q61R-driven melanoma, a cancer with no effective therapy. Remarkably, phendione treatment inhibits the acquisition of resistance to BRAF inhibition in BRAF^V600E PDX highlighting its effectiveness in combating the advent of drug resistance.

Editor’s Note: This article is adapted from the address Ms. Valentine delivered as the recipient of the American Diabetes Association’s (ADA’s) Outstanding Educator in Diabetes Award for 2019. She delivered the address in June 2019 at the Association’s 79th Scientific Sessions in San Francisco, CA. A webcast of this speech is available for viewing at the ADA website (professional.diabetes.org/webcast/outstanding-educator-diabetes-award-lecture%E2%80%94-most-important-thing-we-give-people-hope).

Despite significant advances in therapies for pediatric type 1 diabetes, achievement of glycemic targets remains elusive, and management remains burdensome for patients and their families. This article identifies common challenges in diabetes management at the patient-provider and health care system levels and proposes practical approaches to overcoming therapeutic inertia to enhance health outcomes for youth with type 1 diabetes.

Background and objectives

The effects of active case finding (ACF) models that mobilise community networks for early identification and treatment of tuberculosis (TB) remain unknown. We investigated and compared the effect of community-based ACF using a seed-and-recruit model with one-off roving ACF and passive case finding (PCF) on the time to treatment initiation and identification of bacteriologically confirmed TB.

Pyrazinamide (PZA) is a cornerstone antimicrobial drug used exclusively for the treatment of tuberculosis (TB). Due to its ability to shorten drug therapy by 3 months and reduce disease relapse rates, PZA is considered an irreplaceable component of standard first-line short-course therapy for drug-susceptible TB and second-line treatment regimens for multidrug-resistant TB. Despite over 60 years of research on PZA and its crucial role in current and future TB treatment regimens, the mode of action of this unique drug remains unclear. Defining the mode of action for PZA will open new avenues for rational design of novel therapeutic approaches for the treatment of TB. In this review, we discuss the four prevailing models for PZA action, recent developments in modulation of PZA susceptibility and resistance, and outlooks for future research and drug development.

ABSTRACTBackground:The focused assessment with sonography for HIV-associated tuberculosis (TB) (FASH) ultrasound protocol has been increasingly used to help clinicians diagnose TB. We sought to quantify the diagnostic utility of FASH for TB among individuals with HIV in Malawi.Methods:Between March 2016 and August 2017, 210 adults with HIV who had 2 or more signs and symptoms that were concerning for TB (fever, cough, night sweats, weight loss) were enrolled from a public HIV clinic in Lilongwe, Malawi. The treating clinicians conducted a history, physical exam, FASH protocol, and additional TB evaluation (laboratory diagnostics and chest radiography) on all participants. The clinician made a final treatment decision based on all available information. At the 6-month follow-up visit, we categorized participants based on clinical outcomes and diagnostic tests as having probable/confirmed TB or unlikely TB; association of FASH with probable/confirmed TB was calculated using Fisher's exact tests. The impact of FASH on empiric TB treatment was determined by asking the clinicians prospectively about whether they would start treatment at 2 time points in the baseline visit: (1) after the initial history and physical exam; and (2) after history, physical exam, and FASH protocol.Results:A total of 181 participants underwent final analysis, of whom 56 were categorized as probable/confirmed TB and 125 were categorized as unlikely TB. The FASH protocol was positive in 71% (40/56) of participants with probable/confirmed TB compared to 24% (30/125) of participants with unlikely TB (odds ratio=7.9, 95% confidence interval=3.9,16.1; P<.001). Among those classified as confirmed/probable TB, FASH increased the likelihood of empiric TB treatment before obtaining any other diagnostic studies from 9% (5/56) to 46% (26/56) at the point-of-care. For those classified as unlikely TB, FASH increased the likelihood of empiric treatment from 2% to 4%.Conclusion:In the setting of HIV coinfection in Malawi, FASH can be a helpful tool that augments the clinician's ability to make a timely diagnosis of TB.

Accumulation of lipid in skeletal muscle is thought to be related to the development of insulin resistance and type 2 diabetes. Initial work in this area focused on accumulation of intramuscular triglyceride; however, bioactive lipids such as diacylglycerols and sphingolipids are now thought to play an important role. Specific species of these lipids appear to be more negative toward insulin sensitivity than others. Adding another layer of complexity, localization of lipids within the cell appears to influence the relationship between these lipids and insulin sensitivity. This article summarizes how accumulation of total lipids, specific lipid species, and localization of lipids influence insulin sensitivity in humans. We then focus on how these aspects of muscle lipids are impacted by acute and chronic aerobic and resistance exercise training. By understanding how exercise alters specific species and localization of lipids, it may be possible to uncover specific lipids that most heavily impact insulin sensitivity.

At the end of 2019 and early 2020, an outbreak of pneumonia of unknown etiology emerged in the city of Wuhan in China. The cases were found to be caused by a novel beta coronavirus, which was subsequently named SARS-CoV-2 by the World Health Organization (WHO). The virus has since spread further in China and to other regions of the world, having infected more than 88 K people, and causing close to 3000 deaths as of March 1, 2020. More than 50 million people remain in quarantine at this time. Scientists and clinicians globally are working swiftly to combat COVID-19, the respiratory disease caused by the virus. Notably, diagnostic assays have been developed rapidly in many countries, and have played significant roles in diagnosis, monitoring, surveillance, and infection control. Starting February 29, 2020, the development and performance of molecular testing for SARS-CoV-2 in high complexity Clinical Laboratory Improvement Amendments (CLIA) laboratories prior to emergency use authorization was allowed by the US FDA. Although the epidemic is evolving rapidly, many valuable lessons have been learned and many questions remain to be answered. Here we invited multiple experts across the globe from clinical laboratories, public health laboratories, infection control, and diagnostic industry to share their views on the diagnosis, infection control, and public perception of SARS-CoV-2.

A 40-year-old, male non-smoker was diagnosed with asthma 6 years ago. He now presents with a 1-week history of worsening breathlessness with fever, cough, and purulent expectoration. He has had >10 emergency department visits and two admissions to hospital in the last 3 months. At each admission, he received bronchodilators and systemic steroids resulting in rapid improvement within 24 h. However, in the current presentation, the patient has no relief with corticosteroids and bronchodilators. His pulse is 140 per min, respiratory rate is 40 per min, blood pressure is 90/60 mmHg and room air oxygen saturation is 80%. Arterial blood gas (ABG) analysis shows hypercapnic respiratory failure. In view this respiratory failure, the patient is intubated and mechanical ventilation initiated. A chest radiograph is shown in figure 1. The therapy initiated includes bronchodilators, a systemic steroid, antibiotics and supportive care.

Caseum, the central necrotic material of tuberculous lesions, is a reservoir of drug-recalcitrant persisting mycobacteria. Caseum is found in closed nodules and in open cavities connecting with an airway. Several commonly accepted characteristics of caseum were established during the preantibiotic era, when autopsies of deceased tuberculosis (TB) patients were common but methodologies were limited. These pioneering studies generated concepts such as acidic pH, low oxygen tension, and paucity of nutrients being the drivers of nonreplication and persistence in caseum. Here we review widely accepted beliefs about the caseum-specific stress factors thought to trigger the shift of Mycobacterium tuberculosis to drug tolerance. Our current state of knowledge reveals that M. tuberculosis is faced with a lipid-rich diet rather than nutrient deprivation in caseum. Variable caseum pH is seen across lesions, possibly transiently acidic in young lesions but overall near neutral in most mature lesions. Oxygen tension is low in the avascular caseum of closed nodules and high at the cavity surface, and a gradient of decreasing oxygen tension likely forms toward the cavity wall. Since caseum is largely made of infected and necrotized macrophages filled with lipid droplets, the microenvironmental conditions encountered by M. tuberculosis in foamy macrophages and in caseum bear many similarities. While there remain a few knowledge gaps, these findings constitute a solid starting point to develop high-throughput drug discovery assays that combine the right balance of oxygen tension, pH, lipid abundance, and lipid species to model the profound drug tolerance of M. tuberculosis in caseum.