Diabetic retinopathy (DR) is diagnosed clinically by directly viewing retinal vascular changes during ophthalmoscopy or through fundus photographs. However, electroretinography (ERG) studies in humans and rodents have revealed that retinal dysfunction is demonstrable prior to the development of visible vascular defects. Specifically, delays in dark-adapted ERG oscillatory potential (OP) implicit times in response to dim flash stimuli (<-1.8 log cd·s/m²) occur prior to clinically-recognized diabetic retinopathy. Animal studies suggest that retinal dopamine deficiency underlies these early functional deficits. Here, we randomized persons with diabetes, without clinically detectable retinopathy, to treatment with either low or high dose Sinemet (levodopa plus carbidopa) for 2 weeks and compared their ERG findings with those of control (no DM) subjects. We assessed dim flash stimulated OP delays using a novel hand-held ERG system (RETeval) at baseline, 2 and 4 weeks. RETeval recordings identified significant OP implicit-time delays in persons with diabetes without retinopathy compared to age-matched controls (p<0.001). After two weeks of Sinemet treatment, OP implicit times were restored to control values, and these improvements persisted even after a two-week washout. We conclude that detection of dim flash OP delays could provide early detection of DR, and that Sinemet treatment may reverse retinal dysfunction.

Clinical studies have shown a link between hyperuricemia (HU) and diabetes, while the exact effect of soluble serum urate on glucose metabolism remains elusive. This study aims to characterize the glucose metabolic phenotypes and investigate the underlying molecular mechanisms using a novel spontaneous HU mouse model in which the Uricase (Uox) gene is absent. In an attempt to study the role of HU in glycometabolism, we implemented external stimulation on Uox-knockout (KO) and wild-type (WT) males with a high-fat diet (HFD) and/or injections of multiple low-dose streptozotocin (MLD-STZ) to provoke the potential role of urate. Notably, while Uox-KO mice developed glucose intolerance in the basal condition, no mice spontaneously developed diabetes, even with aging. HFD-fed Uox-KO mice manifested similar insulin sensitivity compared with WT controls. HU augmented the existing glycometabolism abnormality induced by MLD-STZ and eventually led to diabetes, as evidenced by the increased random glucose. Reduced β-cell masses and increased terminal deoxynucleotidyl TUNEL-positive β-cells suggested that HU-mediated diabetes was cell death dependent. However, urate-lowering treatment (ULT) cannot ameliorate the diabetes incidence or reverse β-cell apoptosis with significance. ULT displayed a significant therapeutic effect of HU-crystal– associated kidney injury and tubulointerstitial damage in diabetes. Moreover, we present transcriptomic analysis of isolated islets, using Uox-KO versus WT mice and streptozotocin-induced diabetic WT (STZ-WT) versus diabetic Uox-KO (STZ-KO) mice. Shared differentially expressed genes of HU primacy revealed Stk17β is a possible target gene in HU-related β-cell death. Together, this study suggests that HU accelerates but does not cause diabetes by inhibiting islet β-cell survival.

The purpose of this study was to investigate the protective role of Peroxisome Proliferator-Activated Receptor-alpha (PPARα) against diabetic keratopathy and corneal neuropathy. Corneal samples were obtained from diabetic and non-diabetic human donors. Streptozotocin-induced diabetic rats and mice were orally treated with PPARα agonist fenofibrate. As shown by immunohistochemistry and Western blotting, PPARα was down-regulated in the corneas of diabetic humans and rats. Immunostaining of β-III tubulin demonstrated that corneal nerve fiber metrics were decreased significantly in diabetic rats and mice, which was partially prevented by fenofibrate treatment. As evaluated using a Cochet-Bonnet aesthesiometer, corneal sensitivity was significantly decreased in diabetic mice, which was prevented by fenofibrate. PPARα^-/- mice displayed progressive decreases in the corneal nerve fiber density. Consistently, corneal sensitivity was decreased in PPARα^-/- mice relative to wild-type mice by nine months of age. Diabetic mice showed increased incidence of spontaneous corneal epithelial lesion, which was prevented by fenofibrate while exacerbated by PPARα knockout. Western blot analysis revealed significantly altered neurotrophic factor levels in diabetic rat corneas, which were partially restored by fenofibrate treatment. These results indicate that PPARα protects corneal nerve from degeneration induced by diabetes, and PPARα agonists have therapeutic potential in the treatment of diabetic keratopathy.

Diabetes occurs due to a loss of functional β-cells, resulting from β-cell death and dysfunction. Lactogens protect rodent and human β-cells in vitro and in vivo against triggers of β-cell cytotoxicity relevant to diabetes, many of which converge onto a common pathway, endoplasmic reticulum (ER) stress. However, whether lactogens modulate the ER stress pathway is unknown. This study examines if lactogens can protect β-cells against ER stress and mitigate diabetes incidence in Akita mice, a rodent model of ER stress-induced diabetes, akin to neonatal diabetes in humans. We show that lactogens protect INS1 cells, primary rodent and human β-cells in vitro against two distinct ER stressors, tunicamycin and thapsigargin, through activation of the JAK2/STAT5 pathway. Lactogens mitigate expression of pro-apoptotic molecules in the ER stress pathway that are induced by chronic ER stress in INS1 cells and rodent islets. Transgenic expression of placental lactogen in β-cells of Akita mice drastically reduces the severe hyperglycemia, diabetes incidence, hypoinsulinemia, β-cell death, and loss of β-cell mass observed in Akita littermates. These are the first studies in any cell type demonstrating lactogens modulate the ER stress pathway, causing enhanced β-cell survival and reduced diabetes incidence in the face of chronic ER stress.

Diabetic Keratopathy, a sight-threatening corneal disease, comprises several symptomatic conditions including delayed epithelial wound healing, recurrent erosions, and sensory nerve (SN) neuropathy. We investigated the role of neuropeptides in mediating corneal wound healing, including epithelial wound closure and SN regeneration. Denervation by Resiniferatoxin severely impaired corneal wound healing and markedly up-regulated pro-inflammatory gene expression. Exogenous neuropeptides CGRP, SP, and VIP partially reversed Resiniferatoxin’s effects, with VIP specifically inducing IL-10 expression. Hence, we focused on VIP and observed that wounding induced VIP and VIPR1 expression in normal (NL), but not diabetic (DM) mouse corneas. Targeting VIPR1 in NL corneas attenuated corneal wound healing, dampened wound-induced expression of neurotrophic factors, and exacerbated inflammatory responses while exogenous VIP had the opposite effects in DM corneas. Remarkably, wounding and diabetes also affected the expression of Sonic Hedgehog (SHH) in a VIP-dependent manner. Downregulating SHH expression in NL corneas decreased, while exogenous SHH in DM corneas increased the rates of corneal wound healing. Furthermore, inhibition of SHH signaling dampened VIP-promoted corneal wound healing. We conclude that VIP regulates epithelial wound healing, inflammatory response, and nerve regeneration in the corneas in a SHH-dependent manner, suggesting a therapeutic potential for these molecules in treating diabetic keratopathy.

Cardiac glucose uptake and oxidation are reduced in diabetes despite hyperglycemia. Mitochondrial dysfunction contributes to heart failure in diabetes. It is unclear if these changes are adaptive or maladaptive. To directly evaluate the relationship between glucose delivery and mitochondrial dysfunction in diabetic cardiomyopathy we generated transgenic mice with inducible cardiomyocyte-specific expression of the glucose transporter (GLUT4). We examined mice rendered hyperglycemic following low-dose streptozotocin prior to increasing cardiomyocyte glucose uptake by transgene induction. Enhanced myocardial glucose in non-diabetic mice decreased mitochondrial ATP generation and was associated with echocardiographic evidence of diastolic dysfunction. Increasing myocardial glucose delivery after short-term diabetes onset, exacerbated mitochondrial oxidative dysfunction. Transcriptomic analysis revealed that the largest changes, driven by glucose and diabetes, were in genes involved in mitochondrial function. This glucose-dependent transcriptional repression was in part mediated by O-GlcNAcylation of the transcription factor Sp1. Increased glucose uptake induced direct O-GlcNAcylation of many electron transport chain subunits and other mitochondrial proteins. These findings identify mitochondria as a major target of glucotoxicity. They also suggest reduced glucose utilization in diabetic cardiomyopathy might defend against glucotoxicity and caution that restoring glucose delivery to the heart in the context of diabetes could accelerate mitochondrial dysfunction by disrupting protective metabolic adaptations.

Mitochondrial protein FAM3A suppresses hepatic gluconeogenesis and lipogenesis. This study aimed to screen drug(s) that activates FAM3A expression and evaluate its effect(s) on hyperglycemia and steatosis. Drug-repurposing methodology predicted that antidepressive drug doxepin was among the drugs that potentially activated FAM3A expression. Doxepin was further validated to stimulate the translocation of transcription factor HNF4α from the cytoplasm into the nucleus, where it promoted FAM3A transcription to enhance ATP synthesis, suppress gluconeogenesis, and reduce lipid deposition in hepatocytes. HNF4α antagonism or FAM3A deficiency blunted doxepin-induced suppression on gluconeogenesis and lipid deposition in hepatocytes. Doxepin administration attenuated hyperglycemia, steatosis, and obesity in obese diabetic mice with upregulated FAM3A expression in liver and brown adipose tissues (BAT). Notably, doxepin failed to correct dysregulated glucose and lipid metabolism in FAM3A-deficient mice fed on high-fat diet. Doxepin’s effects on ATP production, Akt activation, gluconeogenesis, and lipogenesis repression were also blunted in FAM3A-deficient mouse livers. In conclusion, FAM3A is a therapeutic target for diabetes and steatosis. Antidepressive drug doxepin activates FAM3A signaling pathways in liver and BAT to improve hyperglycemia and steatosis of obese diabetic mice. Doxepin might be preferentially recommended as an antidepressive drug in potential treatment of patients with diabetes complicated with depression.

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.

The C-type lectin receptors (CLRs) form a family of pattern recognition receptors that recognize numerous pathogens, such as bacteria and fungi, and trigger innate immune responses. The extracellular carbohydrate-recognition domain (CRD) of CLRs forms a globular structure that can coordinate a Ca2+ ion, allowing receptor interactions with sugar-containing ligands. Although well-conserved, the CRD fold can also display differences that directly affect the specificity of the receptors for their ligands. Here, we report crystal structures at 1.8–2.3 Å resolutions of the CRD of murine dendritic cell-immunoactivating receptor (DCAR, or Clec4b1), the CLR that binds phosphoglycolipids such as acylated phosphatidyl-myo-inositol mannosides (AcPIMs) of mycobacteria. Using mutagenesis analysis, we identified critical residues, Ala136 and Gln198, on the surface surrounding the ligand-binding site of DCAR, as well as an atypical Ca2+-binding motif (Glu-Pro-Ser/EPS168–170). By chemically synthesizing a water-soluble ligand analog, inositol-monophosphate dimannose (IPM2), we confirmed the direct interaction of DCAR with the polar moiety of AcPIMs by biolayer interferometry and co-crystallization approaches. We also observed a hydrophobic groove extending from the ligand-binding site that is in a suitable position to interact with the lipid portion of whole AcPIMs. These results suggest that the hydroxyl group-binding ability and hydrophobic groove of DCAR mediate its specific binding to pathogen-derived phosphoglycolipids such as mycobacterial AcPIMs.

Barbara H. Braffett
May 1, 2020; 69:1000-1010
Complications

Christer S. Andreassen
Mar 1, 2006; 55:806-812
Complications

Anne Jörns
Apr 1, 2020; 69:624-633
Islet Studies

Marc Y. Donath
Dec 1, 2005; 54:S108-S113
Section III: Inflammation and beta-Cell Death

Juli Bai
Jun 1, 2019; 68:1099-1108
Perspectives in Diabetes

Miriam Cnop
Dec 1, 2005; 54:S97-S107
Section III: Inflammation and beta-Cell Death

Bruce B. Duncan
Jul 1, 2003; 52:1799-1805
Pathophysiology

Michael Brownlee
Jun 1, 2005; 54:1615-1625
Banting Lecture 2004

Jay S. Skyler
Feb 1, 2017; 66:241-255
Perspectives in Diabetes

Mathematical Reviews will be at the JMM in Denver, January 13-18, 2020. The Joint Mathematical Meetings is the largest gathering of mathematicians in the world.  There are lots of great activities:  invited lectures, special sessions, editorial meetings, exhibits, and the chance to … Continue reading →

Mathematics is a useful tool in studying the growth of infections in a population, such as what occurs in epidemics.  A simple model is given by a first-order differential equation, the logistic equation, $frac{dx}{dy}=eta x(1-x)$ which is discussed in almost any … Continue reading →

There is a three-minute video about MathSciNet now available online on Vimeo. It is also available as part of a blog post from EBSCO, which mostly discusses Mathematics and Statistics Awareness Month and the really neat book Living Proof: Stories … Continue reading →

Invitation Only Research Event

Event participants

Arancha González, Executive Director, International Trade Centre
Chair: Marianne Schneider-Petsinger, Research Fellow, US and the Americas Programme, Chatham House

A year-long project focused on what is at stake in the pivotal 2020 US presidential and congressional elections, considering the future of US policy on trade, global economy and technology, national security, transatlantic relations, climate, migration and Latin America.

  So I thought about my brother and sister a lot this weekend. It’s not like me at all. You don’t count on people just, sort of vanishing. I’ve been talking about death since I was born, so with my Dad it was kinda different. I knew he was dying. It was strange. We both […]

Approximately 10% of patients with type 2 diabetes suffer from latent autoimmune diabetes in adults (LADA). This study provides a systematic assessment of the pathology of the endocrine pancreas of patients with LADA and for comparison in a first rat model mimicking the characteristics of patients with LADA. Islets in human and rat pancreases were analyzed by immunohistochemistry for immune cell infiltrate composition, by in situ RT-PCR and quantitative real-time PCR of laser microdissected islets for gene expression of proinflammatory cytokines, the proliferation marker proliferating cell nuclear antigen (PCNA), the anti-inflammatory cytokine interleukin (IL) 10, and the apoptosis markers caspase 3 and TUNEL as well as insulin. Human and rat LADA pancreases showed differences in areas of the pancreas with respect to immune cell infiltration and a changed ratio between the number of macrophages and CD8 T cells toward macrophages in the islet infiltrate. Gene expression analyses revealed a changed ratio due to an increase of IL-1β and a decrease of tumor necrosis factor-α. IL-10, PCNA, and insulin expression were increased in the LADA situation, whereas caspase 3 gene expression was reduced. The analyses into the underlying pathology in human as well as rat LADA pancreases provided identical results, allowing the conclusion that LADA is a milder form of autoimmune diabetes in patients of an advanced age.

The Jamaica Tallawahs have wasted little time in finding a replacement for the ‘Universe Boss’ Chris Gayle, as they have snapped up the captain of the St Kitts and Nevis Patriots, Carlos Brathwaite. The Gleaner has been reliably informed that...

National 400m hurdles champion Rushell Clayton is concerned about what she says are inequalities between men and women in track and field. Clayton was speaking at a Women in Sports Conference in Kingston recently and discussed issues of inequality...

Katherine Henderson is the clinical lead of the emergency department at St Thomas's hospital in London. She worries that lack of ward space is having a domino effect throughout A and E and is the cause of increased waiting time for both patients and ambulances. If you would like to contribute to this collection, please email a brief audio...

A recent review by the Australian National Health and Medical Research Council concluded that “there are no health conditions for which there is reliable evidence that homeopathy is effective”, but Europe currently spends €1bn annually on such remedies - often at the recommendation of doctors. So a recent head to head debate in The BMJ asks,...

Hepatic encephalopathy constitutes a spectrum of neuropsychiatric abnormalities, beginning with subtle psychomotor changes and progressing to confusion with asterixis, somnolence, and then coma, arising in patients with impaired liver function. In this podcast, Tim Cross, a consultant hepatologist from the Royal Liverpool University Hospital,...

The current orthodoxy is that home is the best and preferred place of death for most people, but in this podcast, Kristian Pollock a sociologist from Nottingham University questions these assumptions and calls for greater attention to improving the experience of dying in hospital and elsewhere. Read the full...

Medical error is not included on death certificates or in rankings of cause of death. Martin Makary, professor of surgery at Johns Hopkins University School of Medicine, joins us to explain why we don't measure medical error, and why it is so important that we start. Read the full analysis: http://www.bmj.com/content/353/bmj.i2139

The European Medicines Agency (EMA) has embraced a new model of drug testing and marketing called “adaptive pathways”, allowing new drugs for “unmet medical needs” to be launched on the market faster, on the basis of fewer data. While industry claims this is necessary, an analysis on thebmj.com looks at the assumptions underlying the new pathway,...

Scott Murray, professor of primary palliative care at the University of Edinburgh, has written, and talked in this podcast before, about the benefits of early palliative care - and today he’s back to explain how illness trajectory, and the pattern of decline at the end of life, affects 4 main areas of wellness - physical, social, psychological and...

Findings from a range of prospective cohort studies based around the world indicate that higher intelligence in children is related to a lower risk of all cause mortality in adulthood - and now a new study, published on bmj.com, is trying to dig into that association further, with a whole population cohort and data on cause specific...

Its now widely agreed that one of the key ways of reducing the current high level of "waste " in biomedical research is to focus it more squarely on addressing the questions that matter to patients - and the people and medical staff that care for them. In this interview, Tessa Richards - the BMJ's patient partnership editor, talks to...

This week a very different kind of conversation on the Recommended Dose – one that considers the art of medicine more than the science. Iona Heath is a long-time family doctor who has worked in a London GP clinic for over 30 years, and at one time became President of the Royal College of General Practitioners. With an international profile, gained...

On the 7th of June, 1753, Dr Archibald Cameron was executed at Tyburn. "The body, after hanging twenty minutes, was cut down: it was not quartered; but the heart was taken out and burnt. " 250 years later, his sixth great grandson, Robert Syned found himself deeply involved in the process of execution, as an expert witness in a case about the use...

This week the Trump administration has banned the sale of flavoured vapes in the USA. The reason for that is the sudden rash of cases of pulmonary disease, including deaths, linked to vaping. The mechanism by which vaping may be causing damage to the lungs is as yet unclear, and our understanding is hampered by the heterogeneous nature of the...

For the next few months Talk Evidence is going to focus on the new corona virus pandemic. There is an enormous amount of uncertainty about the disease, what the symptoms are, fatality rate, treatment options, things we shouldn't be doing. We're going to try to get away from the headlines and talk about what we need to know - to hopefully give...

A new podcast from The BMJ, to help GP's feel more connected, heard, and supported. Subscribe on; Apple podcasts - https://bit.ly/applepodsDBI Spotify - https://bit.ly/spotifyDBI Google podcasts - https://bit.ly/googlepodsDBI This week, our topic is fear: we try to get a better understanding of fear, how it affects all of us as clinicians for...

Katalin Susztak
Jan 1, 2006; 55:225-233
Complications

Cindy J.M. Loomans
Jan 1, 2004; 53:195-199
Complications

Christophe Bonny
Jan 1, 2001; 50:77-82
Islet Studies

R A DeFronzo
Dec 1, 1981; 30:1000-1007
Original Contribution

Miriam Cnop
Dec 1, 2005; 54:S97-S107
Section III: Inflammation and beta-Cell Death