Activation of a nonclassical NKT cell subset in a transgenic mouse model of hepatitis B virus infection

NKT cells are specialized cells of the immune system that bear both T cell and NK cell markers. Classical NKT cells display TCRs of restricted heterogeneity (Valpha14-Jalpha281) and recognize lipid antigens (e.g., alpha-galactosyl ceramide) presented by nonpolymorphic CD1 molecules. Recently, other nonclassical NKT subsets have been recognized, including NKT cells not reactive with CD1d-alpha-galactosyl ceramide complexes. The biological functions of these cells are unknown. Here, we show that nonclassical NKT cells that are CD1d restricted but nonreactive to alpha-GalCer are activated in response to hepatocytes expressing hepatitis B viral antigens in a transgenic mouse model of acute hepatitis B virus infection. Our results document the first in vivo function for such nonclassical NKT cells and suggest a role for these cells in the host response to HBV infection.     

Gastrointestinal Adverse Effects of Short-Term Aspirin Use: A Meta-Analysis of Published Randomized Controlled Trials

Background and Objectives

Aspirin is widely used for short-term treatment of pain, fever or colds, but there are only limited data regarding the safety of this use. To summarize the available data on this topic, we conducted a meta-analysis of the published clinical trial literature regarding the gastrointestinal adverse effects of short-term use of aspirin in comparison with placebo and other medications commonly used for the same purpose.

Data Sources and Methods

An extensive literature search identified 119,310 articles regarding possible adverse effects of aspirin, among which 23,131 appeared to possibly include relevant data. An automated text-mining procedure was used to score the references for potential relevance for the meta-analysis. The 3,983 highest-scoring articles were reviewed individually to identify those with data that could be included in this analysis. Ultimately, 78 relevant articles were identified that contained gastrointestinal adverse event data from clinical trials of aspirin versus placebo or an active comparator. Odds ratios (ORs) computed using a Mantel–Haenszel estimator were used to summarize the comparative effects on dyspepsia, nausea/vomiting, and abdominal pain, considered separately and also aggregated as ‘minor gastrointestinal events’. Gastrointestinal bleeds, ulcers, and perforations were also investigated.

Results

Data were obtained regarding 19,829 subjects (34 % treated with aspirin, 17 % placebo, and 49 % an active comparator). About half of the aspirin subjects took a single dose. Aspirin was associated with a higher risk of minor gastrointestinal events than placebo or active comparators: the summary ORs were 1.46 (95 % confidence interval [CI] 1.15–1.86) and 1.81 (95 % CI 1.61–2.04), respectively. Ulcers, perforation, and serious bleeding were not seen after use of aspirin or any of the other interventions.

Conclusions

During short-term use, aspirin is associated with a higher frequency of gastrointestinal complaints than other medications commonly used for treatment of pain, colds, and fever. Serious adverse events were not observed with aspirin or any of the comparators.

Electronic supplementary material

The online version of this article (doi:10.1007/s40268-013-0011-y) contains supplementary material, which is available to authorized users.     

Investigation into the suitability of capillary tubes for microcrystalline testing

A comparison between microcrystalline tests performed on microscope slides and flat capillary tubes with inner diameters ranging from 0.1 to 0.7 mm was carried out to explore the appropriateness of tubes for rapid testing of suspected drugs of abuse in the laboratory as well as in the field. Tests for mephedrone, cocaine, and phencyclidine were chosen as examples to investigate the handling of the capillary tubes, the influence on crystal habit, size, and the effects on the limit of detection. Image stacking software was used to increase the depth of field of micrographs taken from developed microcrystals greatly enhancing the interpretability even months after carrying out the microcrystalline test. Additionally, the potential of seeding capillary tubes with a reagent was studied. Pre‐treatment of tubes would allow microcrystalline tests to be carried out quicker and anywhere without the necessity of taking along expensive and hazardous reagents. The sealing of capillary tubes containing developed microcrystalline tests in order to preserve results for a long period of time was successfully done by applying paraffin wax to the open ends. Finally, it was concluded that capillary tubes are suitable vessels for performing microcrystalline tests. The increased portability of the improved set‐up allows tests to be safely executed outside laboratories without impairing the quality of the result. Findings were applied to six legal high samples purchased online between May and August 2011. The active ingredients like MDAI as well as cutting agents like caffeine were successfully identified using the microcrystalline test technique in capillary tubes. Copyright © 2012 John Wiley & Sons, Ltd.     

Insulin resistance in the vasculature

Insulin resistance is typically defined as a reduced ability of insulin to induce glucose uptake by target tissues such as fat and skeletal muscle cells. It accompanies several disease states, including obesity, type 2 diabetes, hepatitis C, and polycystic ovary syndrome, and is a primary feature of metabolic syndrome. Outside of its effects on blood glucose levels, insulin resistance is also associated with a 2- to 3-fold increased risk of cardiovascular mortality. In 1996, Alain Baron, Helmut Steinberg, and colleagues demonstrated that insulin resistance is associated with endothelial dysfunction. This seminal observation led to significant advances in our understanding of insulin’s action in health and disease.In the mid-1990s, our lab produced seminal observations demonstrating that insulin-mediated augmentation of skeletal muscle blood flow was a physiologic feature of insulin’s action in humans (1). Moreover, in the insulin-resistant states of human obesity and type 2 diabetes, this vascular action of insulin was impaired (2). These studies used femoral arterial catheterizations to evaluate the response to intra-arterial vasodilator stimuli, comparing control conditions against euglycemic-hyperinsulinemic clamp conditions. Obesity was associated with parallel defects in the vasodilatory responses to insulin and to methacholine, an endothelium-dependent vasodilator. We further demonstrated that the vasodilatory effects of insulin were mediated by the release of endothelial nitric oxide, and we and others demonstrated that blocking nitric oxide production in vivo could induce insulin resistance and inhibit glucose uptake by preventing insulin-mediated vasodilation in skeletal muscle (3). Finally, we demonstrated that endothelial dysfunction, characterized by reduced nitric oxide production and exaggerated release of endothelin, was a key feature of human insulin-resistant states (4). The link between insulin resistance and endothelial dysfunction is now widely accepted, and there is broad recognition that insulin’s action to enhance its own vascular delivery (and that of its substrates) is integral to its overall action. These observations have prompted much subsequent work, including the exploration of the cellular and molecular details of the vascular actions of insulin. Quon and colleagues demonstrated that the molecular signaling pathways mediating insulin stimulation of nitric oxide production in endothelial cells are similar to signaling pathways mediating insulin activation of glucose transport in classical target tissues (i.e., the PI 3-kinase pathway) (5). Among many experiments confirming these observations, mice with defective insulin signaling (Irs1 knockout) exhibited impaired endothelial function and insulin resistance (6). While insulin in endothelial cells also acts via a MAP kinase pathway independent of impaired insulin receptor/IRS-1 signaling (5), in the setting of impaired endothelial IRS-1 function, insulin preferentially activates the MAP kinase pathway, resulting in a mitogenic, proatherosclerotic response in the vascular wall. These effects are prominently driven by endothelin. Excess endothelin action appears to contribute to insulin resistance in human obesity (4). A current model suggests that endothelial insulin sensitivity determines a balance between the vasculoprotective PI 3-kinase and proatherogenic MAP kinase pathways (Figure ​(Figure11). Open in a separate windowFigure 1Distinct signaling pathways mediate insulin effects on nitric oxide and endothelin in vascular endothelial cells.Endothelial insulin resistance can preferentially impair signaling via the IRS/PI3K pathway, adversely affecting the balance between prothrombotic and antithrombotic signaling. This imbalance could potentially contribute to the increased cardiovascular mortality associated with insulin resistance.The observation that insulin’s vasodilatory actions are impaired in obesity and insulin resistance has also prompted studies exploring the location of this action in the vascular tree. Using a clever microbubble technique, the Barrett and Clark laboratories demonstrated that insulin acts in a nitric oxide–dependent fashion to regulate capillary recruitment and perfusion by affecting precapillary resistance vessels (7). Importantly, this action of insulin precedes the induction of glucose uptake (8), demonstrating that the vascular effects of insulin are primary and do not arise as a consequence of changes in cellular metabolism. These same authors have confirmed that insulin resistance is associated with impaired capillary recruitment and altered skeletal muscle perfusion. Recognition of impaired vascular actions of insulin in obesity and insulin resistance has recast prior observations of the contributions of fatty acids and inflammation to systemic insulin resistance and the role of other metabolically active hormones on the vasculature. Fatty acid excess (particularly palmitic acid), previously known to cause insulin resistance, also induces tissue and vascular insulin resistance (9). Inflammation is associated with vascular dysfunction, and fatty acids appear to act in part by inducing local inflammation. Fatty acid lowering achieved with nicotinic acid or with PPARγ agonists has proven beneficial for vascular function and for insulin sensitivity, but the presence of multiple concurrent effects prevents simple assessment of underlying causal relationships. Therapeutically reducing systemic inflammation has been surprisingly ineffective at improving vascular function in diabetes. In general, interventions that improve insulin action have also been shown to ameliorate endothelial function. Whether improved endothelial function could result in improved insulin action has not been shown. The effects of other fuel hormones on the vasculature have also been evaluated. Most recently, studies with glucagon-like peptide 1 (GLP-1) have shown that it can act similarly to insulin as a microvascular vasodilator in skeletal muscle (10). Additionally, GLP-1 appears to regulate myocardial perfusion and fuel selection (observations that are leading to clinical studies of GLP-1 in the setting of myocardial ischemia). Further study is required to evaluate the impact of diabetes and obesity on the vascular effects of GLP-1 and other fuel hormones, and to evaluate the therapeutic application of these observations. Much remains to be learned regarding insulin’s vascular effects and the role of endothelial insulin resistance in the pathogenesis of atherosclerosis. It is interesting to speculate that correction of endothelial vascular resistance, independent of insulin action in other tissues, may be sufficient to reduce the risk of insulin resistance–associated vascular disease.     

Age-dependent hepatic lymphoid organization directs successful immunity to hepatitis B

Hepatitis B virus (HBV) is a major human pathogen that causes immune-mediated hepatitis. Successful immunity to HBV is age dependent: viral clearance occurs in most adults, whereas neonates and young children usually develop chronic infection. Using a mouse model of HBV infection, we sought mechanisms underpinning the age-dependent outcome of HBV and demonstrated that hepatic macrophages facilitate lymphoid organization and immune priming within the adult liver and promote successful immunity. In contrast, lymphoid organization and immune priming was greatly diminished in the livers of young mice, and of macrophage-depleted adult mice, leading to abrogated HBV immunity. Furthermore, we found that CXCL13, which is involved in B lymphocyte trafficking and lymphoid architecture and development, is expressed in an age-dependent manner in both adult mouse and human hepatic macrophages and plays an integral role in facilitating an effective immune response against HBV. Taken together, these results identify some of the immunological mechanisms necessary for effective control of HBV.     

Contribution of the laboratory in hypoglycemia diagnosis induced by insulin administration in a 2-year-old girl

We report the case of a 2 year-old child presented to the emergency department following a seizure. The child was hypotonic and examination was unremarkable but laboratory tests confirmed a severe hypoglycaemia. The insulin level, inappropriately high for the glycemia and the peptide C undetectable suggested exogenous hyperinsulinism. We conclude that the hypoglycaemia was likely the result of Munchhausen syndrome by proxy. The specificity of two immunoassays used (Elecsys Roche and IRMA CisBio) for the synthetic analogues of insulin explains the discrepancy between the insulin levels obtained but was crucially useful to the approach of the cause of the hypoglycaemia.     

Bilateral Iliac Vein Filter Deployment in a Patient with Megacava

An 85-year-old-woman presenting with low back pain developed shortness of breath and right-sided chest pain. She was found to have perfusion defects indicative of pulmonary embolus (PE). Heparin was at first employed, but had to be discontinued because of gastrointestinal bleeding. Caval filtration was the obvious course, but it was found on computed tomography (CT) scan that the suprarenal portion of the inferior vena cava was 55 mm in diameter, and the infrarenal portion 44 mm. These measurements were too large for insertion of a Greenfield filter, for which the maximum diameter should be 28 mm. The right common iliac vein was 28 mm in diameter, and the left external iliac vein 25 mm. Two filters were inserted percutaneously in these vessels. The patient was followed for 9 months. No clinical evidence of recurrent PE or venous insufficiency occurred.