Cardiac spinal deafferentation reduces the susceptibility to sustained ventricular tachycardia in conscious rats

The response to myocardial ischemia is complex and involves the cardio-cardiac sympathetic reflex. Specifically, cardiac spinal (sympathetic) afferents are excited by ischemic metabolites and elicit an excitatory sympathetic reflex, which plays a major role in the genesis of ventricular arrhythmias. For example, brief myocardial ischemia leads to ATP release, which activates cardiac spinal afferents through stimulation of P2 receptors. Clinical work with patients and preclinical work with animals document that disruption of this reflex protects against ischemia-induced ventricular arrhythmias. However, the role of afferent signals in the initiation of sustained ventricular tachycardia has not been investigated. Therefore, we tested the hypothesis that cardiac spinal deafferentation reduces the susceptibility to sustained ventricular tachycardia in adult (12-15 wk of age), conscious, male Sprague-Dawley rats. To test this hypothesis, the susceptibility to ventricular tachyarrhythmias produced by occlusion of the left main coronary artery was determined in two groups of conscious rats: 1) deafferentation (bilateral excision of the T1-T5 dorsal root ganglia) and 2) control (sham deafferentation). The ventricular arrhythmia threshold (VAT) was defined as the time from coronary occlusion to sustained ventricular tachycardia resulting in a reduction in arterial pressure. Results document a significantly higher VAT in the deafferentation group (7.0 ± 0.7 min) relative to control (4.3 ± 0.3 min) rats. The decreased susceptibility to tachyarrhythmias with deafferentation was associated with a reduced cardiac metabolic demand (lower rate-pressure product and ST segment elevation) during ischemia.     

Agency,intimacy, and rape jokes: an ethnographic study of young women and sexual risk in Chennai

In this article, I examine the circulation of jokes about sexual violence among young middle‐class women in the South Indian city of Chennai. Drawing on ethnographic research with undergraduate students in this city, I locate the rape joke in an ambivalent discourse of risk that conflates the possibility of sexual assault with the perceived ‘risks’ of women's sexual autonomy. In this context, I argue that humour about sexual violence functions as a form of lateral agency, facilitating a break from the task of reproducing middle‐class respectability.     

Exploratory algorithm to devise multi-epitope subunit vaccine by investigating Leishmania donovani membrane proteins

Visceral leishmaniasis (VL) is a deadly parasitic infection which affects poorest to poor population living in the endemic countries. Increasing resistant to existing drugs, disease burden and a significant number of deaths, necessitates the need for an effective vaccine to prevent the VL infection. This study employed a combinatorial approach to develop a multi-epitope subunit vaccine by exploiting Leishmania donovani membrane proteins. Cytotoxic T- and helper T-lymphocyte binding epitopes along with suitable adjuvant and linkers were joined together in a sequential manner to design the subunit vaccine. The occurrence of B-cell and IFN-γ inducing epitopes approves the ability of subunit vaccine to develop humoral and cell-mediated immune response. Physiochemical parameters of vaccine protein were also assessed followed by homology modeling, model refinement and validation. Moreover, disulfide engineering was performed for the increasing stability of the designed vaccine and molecular dynamics simulation was performed for the comparative stability purposes and to conform the geometric conformations. Further, molecular docking and molecular dynamics simulation study of a mutated and non-mutated subunit vaccine against TLR-4 immune receptor were performed and respective complex stability was determined. In silico cloning ensures the expression of designed vaccine in pET28a(+) expression vector. This study offers a cost-effective and time-saving way to design a novel immunogenic vaccine that could be used to prevent VL infection.

Communicated by Ramaswamy H. Sarma     

Cartilage interstitial fluid load support in unconfined compression

Under physiological conditions of loading, articular cartilage is subjected to both compressive strains, normal to the articular surface, and tensile strains, tangential to the articular surface. Previous studies have shown that articular cartilage exhibits a much higher modulus in tension than in compression, and theoretical analyses have suggested that this tension–compression nonlinearity enhances the magnitude of interstitial fluid pressurization during loading in unconfined compression, above a theoretical threshold of 33% of the average applied stress. The first hypothesis of this experimental study is that the peak fluid load support in unconfined compression is significantly greater than the 33% theoretical limit predicted for porous permeable tissues modeled with equal moduli in tension and compression. The second hypothesis is that the peak fluid load support is higher at the articular surface side of the tissue samples than near the deep zone, because the disparity between the tensile and compressive moduli is greater at the surface zone. Ten human cartilage samples from six patellofemoral joints, and 10 bovine cartilage specimens from three calf patellofemoral joints were tested in unconfined compression. The peak fluid load support was measured at 79±11% and 69±15% at the articular surface and deep zone of human cartilage, respectively, and at 94±4% and 71±8% at the articular surface and deep zone of bovine calf cartilage, respectively. Statistical analyses confirmed both hypotheses of this study. These experimental results suggest that the tension–compression nonlinearity of cartilage is an essential functional property of the tissue which makes interstitial fluid pressurization the dominant mechanism of load support in articular cartilage.     

Binding Cooperativity Matters: A GM1-Like Ganglioside-Cholera Toxin B Subunit Binding Study Using a Nanocube-Based Lipid Bilayer Array

Protein-glycan recognition is often mediated by multivalent binding. These multivalent bindings can be further complicated by cooperative interactions between glycans and individual glycan binding subunits. Here we have demonstrated a nanocube-based lipid bilayer array capable of quantitatively elucidating binding dissociation constants, maximum binding capacity, and binding cooperativity in a high-throughput format. Taking cholera toxin B subunit (CTB) as a model cooperativity system, we studied both GM₁ and GM₁-like gangliosides binding to CTB. We confirmed the previously observed CTB-GM₁ positive cooperativity. Surprisingly, we demonstrated fucosyl-GM₁ has approximately 7 times higher CTB binding capacity than GM₁. In order to explain this phenomenon, we hypothesized that the reduced binding cooperativity of fucosyl-GM₁ caused the increased binding capacity. This was unintuitive, as GM₁ exhibited higher binding avidity (16 times lower dissociation constant). We confirmed the hypothesis using a theoretical stepwise binding model of CTB. Moreover, by taking a mixture of fucosyl-GM₁ and GM₂, we observed the mild binding avidity fucosyl-GM₁ activated GM₂ receptors enhancing the binding capacity of the lipid bilayer surface. This was unexpected as GM₂ receptors have negligible binding avidity in pure GM₂ bilayers. These unexpected discoveries demonstrate the importance of binding cooperativity in multivalent binding mechanisms. Thus, quantitative analysis of multivalent protein-glycan interactions in heterogeneous glycan systems is of critical importance. Our user-friendly, robust, and high-throughput nanocube-based lipid bilayer array offers an attractive method for dissecting these complex mechanisms.     

Mammalian brain plasma membranes : Isolation, enzymatic, and chemical characterization

Two variants of a simplified procedure for the isolation of plasma membrane fractions from monkey and rat brains, are described. The preparations show marked enrichments in the marker enzymes, (Na⁺-K⁺) adenosine triphosphatase, acetylcholinesterase, 5′-nucleotidase and adenylate cyclase. Lipid analysis and a protein electrophoretic pattern are presented. An enzymatic check has been made to assess for contamination by other cellular organelles. The amino acid composition of brain membrane proteins show a resemblance to the reported composition of erythrocyte ghost proteins but differ from myelin proteins.     

Exercise and diet enhance fat oxidation and reduce insulin resistance in older obese adults.

Older, obese, and sedentary individuals are at high risk of developing diabetes and cardiovascular disease. Exercise training improves metabolic anomalies associated with such diseases, but the effects of caloric restriction in addition to exercise in such a high-risk group are not known. Changes in body composition and metabolism during a lifestyle intervention were investigated in 23 older, obese men and women (aged 66 +/- 1 yr, body mass index 33.2 +/- 1.4 kg/m(2)) with impaired glucose tolerance. All volunteers undertook 12 wk of aerobic exercise training [5 days/wk for 60 min at 75% maximal oxygen consumption (Vo(2max))] with either normal caloric intake (eucaloric group, 1,901 +/- 277 kcal/day, n = 12) or a reduced-calorie diet (hypocaloric group, 1,307 +/- 70 kcal/day, n = 11), as dictated by nutritional counseling. Body composition (decreased fat mass; maintained fat-free mass), aerobic fitness (Vo(2max)), leptinemia, insulin sensitivity, and intramyocellular lipid accumulation (IMCL) in skeletal muscle improved in both groups (P < 0.05). Improvements in body composition, leptin, and basal fat oxidation were greater in the hypocaloric group. Following the intervention, there was a correlation between the increase in basal fat oxidation and the decrease in IMCL (r = -0.53, P = 0.04). In addition, basal fat oxidation was associated with circulating leptin after (r = 0.65, P = 0.0007) but not before the intervention (r = 0.05, P = 0.84). In conclusion, these data show that exercise training improves resting substrate oxidation and creates a metabolic milieu that appears to promote lipid utilization in skeletal muscle, thus facilitating a reversal of insulin resistance. We also demonstrate that leptin sensitivity is improved but that such a trend may rely on reducing caloric intake in addition to exercise training.