The fibrinogen gamma chain dodecapeptide inhibits agonist-induced aggregation of rabbit platelets and fibrinogen binding to rabbit glycoprotein IIb-IIIa

The HHLGGAKQAGDV (H12) sequence at the carboxyl termini of the y chains and the RGD sequences in the Aalpha chains of human fibrinogen are potential recognition sites for the binding of soluble fibrinogen to glycoprotein IIb-IIIa (GPIIb-IIIa) on activated human platelets. Thus, addition of either H12 or RGD-containing peptides inhibits aggregation of and fibrinogen binding to human platelets. In contrast, we reported previously that RGDS had relatively little inhibitory effect on these functions of rabbit platelets. In the present study, we found that H12 inhibited ADP- and thrombin-induced aggregation of rabbit platelets in a dose-dependent manner. Specificity was demonstrated by the failure of the variant HHLGGAKQAGEV peptide to inhibit ADP-induced aggregation. Furthermore, flow cytometric analyses demonstrated that H12 inhibited the binding of FITC-fibrinogen to ADP-activated rabbit platelets in a dose-dependent manner. To examine the direct interaction of H12 with rabbit GPIIb-IIIa, we performed affinity chromatography by applying an octylglucoside extract of rabbit platelet proteins onto an affinity matrix containing the fibrinogen gamma chain sequence. Proteins of approximately 135 kDa and approximately 95 kDa were specifically eluted by soluble H12, and the 95 kDa protein band was immunoblotted by anti-LIBS1, a monoclonal antibody against human GPIIIa. In control samples, no detectable protein from rabbit platelet lysates was eluted from an RGD affinity matrix by GRGDSP. Collectively, our results demonstrated that H12 inhibits aggregation of and fibrinogen binding to rabbit platelets by directly interacting with rabbit GPIIb-IIIa. These findings suggest that rabbit platelets would serve as a suitable thrombosis model for testing the efficacy of peptide mimetics derived from H12.     

Distribution of thoracic lymphadenopathy in sarcoidosis using computed tomography

The authors used chest computed tomography to determine the distribution of pulmonary lymphadenopathy in 40 patients with sarcoidosis. Using the American Thoracic Society lymph node map, the number and distribution of significant lymph nodes was calculated. Overall, lymphadenopathy was identified in 39 of the 40 patients. Mediastinal adenopathy was present in 38 patients, and hilar adenopathy was present in 27. Commonly involved nodal stations were 4R, 5, 7, 10R, 11R, and 11L, and little involvement was seen in stations 1, 6, and 14. An understanding of the common sites of adenopathy in sarcoidosis is useful when assessing adenopathy in patients without a known diagnosis.     

The glyoxylate cycle enzyme activities in the pathogenic isolates of Candida albicans obtained from HIV/AIDS, diabetic and burn patients

Recently it has been found that Candida albicans harbours enzymes involved in the glyoxylate cycle (GC), which have a role in its virulence, especially the two key enzymes, isocitrate lyase (ICL) and malate synthase (MS). There are however, few studies on the GC enzyme activities isolated in the clinical isolates. Samples were collected from three groups of patients namely, HIV/AIDS, diabetic and burn patients suffering from candidiasis at different body locations. Isolation, identification and the antifungal susceptibility test of all the isolates of C. albicans were followed by the standard techniques. Measurements of all the GC enzyme activities were also carried out by the standard methods. Levels of the principal GC enzymes showed significant changes when calculated and compared taking control strains of C. albicans. The activity of the two key enzymes of the GC, ICL and MS were significantly higher in the isolates from diabetic patients. No significant relationship between the drug susceptibility and the level of enzymes of the GC was observed. As GC activity is absent in mammalian cells, a specific inhibitor for the GC could be developed and these enzymes therefore can be used as a new antifungal target.     

Biodegradable microparticulate system of captopril

Albumin microparticles have found many applications in diagnosis and treatment in recent years and more than 100 diagnostic agents and drugs have been incorporated into albumin microparticles. In the present study, bovine serum albumin (BSA) based microparticles bearing captopril were prepared by an emulsification-heat stabilization technique. Four batches of microparticles with varying ratio of drug and polymer were prepared. The prepared microparticles were studied for drug loading, particle size distribution, in vitro release characteristics, in vivo tissue distribution study and stability studies. The microparticles had mean diameter between 2 and 11 microm of which more than 70% were below 5 microm and incorporation efficiency of 41-63% was obtained. In vitro release profile for formulations containing captopril-loaded albumin microparticles with heat stabilizing technique shows slow controlled release up to 24 h. The in vivo result of drug-loaded microparticles showed preferential drug targeting to liver followed by lungs, kidneys and spleen. Stability studies showed that maximum drug content and closest in vitro release to initial data were found in the formulation stored at 4 degrees C. In the present study, captopril-loaded BSA microparticles were prepared and targeted to various organs to a satisfactory level and were found to be stable at 4 degrees C.     

Elevation of systolic blood pressure in an animal model of olanzapine induced weight gain

In the present study, we examined the effect of olanzapine on weight gain, systolic blood pressure and metabolic changes in rats. Female Sprague Dawley rats were treated with either vehicle or olanzapine (1 and 2 mg/kg i.p, twice daily) for 20 days. Body weight, food and water intake, systolic blood pressure, plasma glucose, insulin and lipid were measured. Olanzapine (1 and 2 mg/kg) significantly increased the body weight and systolic blood pressure. Whereas, food intake and plasma insulin and insulin resistance index, were elevated only at 1 mg/kg. In conclusion, olanzapine induced weight gain in rats is associated with elevation of systolic blood pressure.     

Modulatory effect of sildenafil in diabetes and electroconvulsive shock-induced cognitive dysfunction in rats

The nitric oxide/guanylyl cyclase, cyclic guanosine monophosphate/phosphodiesterase 5 (NO/cGMP/PDE5) pathways play a key role in physiological and pathological situations, such as synaptic plasticity, learning and memory formation, diabetic gastropathy and neuropathy, long-term potentiation (LTP), epilepsy, cerebral ischemia, and neurodegenerative diseases. Several studies have demonstrated the alteration of NO-cGMP pathway in cognitive impairment. The present study was aimed to study the effect of sildenafil, a PDE5 inhibitor on diabetes and electroconvulsive shock (ECS)-induced cognitive dysfunction in rat using one-trial step-through type of passive avoidance and elevated plus-maze task. Diabetic and ECS-treated rats showed poor learning performance in step-through passive avoidance and plus-maze task. Acute administration of sildenafil significantly reversed the diabetes and ECS-induced retention deficits in both the test paradigms. Sildenafil also significantly improved the cognitive performance in young rats in both the paradigms. Furthermore, L-NAME, a non-selective NOS inhibitor and methylene blue, a guanylate cyclase inhibitor blocked the effect of sildenafil. The results thus suggest that cognitive impairment might be due to the modulatory effect of nNOS or PDE5 enzyme on cGMP levels. Moreover, sildenafil-induced reversal of cognitive impairment suggests the protective role of PDE5 inhibitors in neurodegenerative disorders.     

Citrus juice modulates antioxidant enzymes and lipid profiles in orchidectomized rats

Oxidative stress and hypogonadism are two factors linked to the increased incidence of cardiovascular disease in males. Eating fruits and vegetables is known to reduce the incidences of oxidative stress. The objective of this research was to delineate whether drinking daily squeezed orange juice (OJ) or grapefruit juice (GJ) modulates oxidative stress and antioxidant enzymes while impacting cardiovascular risk factors in hypogonad male rats. In the present study, 36 1-year-old male rats were equally divided among the following four treatments: sham (control), orchidectomized (ORX), ORX + OJ, and ORX + GJ. After 60 days of drinking OJ or GJ, antioxidant capacity, cholesterol, and triglycerides in serum and superoxide dismutase (SOD), catalase (CAT), cholesterol, and triglycerides in liver were evaluated. Serum antioxidant capacity and SOD and CAT activities decreased (P < .05), while serum cholesterol and liver triglycerides increased (P < .05) in the ORX group compared with the sham group. In contrast to the ORX group, drinking OJ was ineffective while drinking GJ decreased (P < .05) cholesterol concentration in liver and in serum. Nevertheless, OJ and GJ decreased (P < .05) triglyceride concentration in liver and increased (P < .05) serum antioxidant capacity and SOD and CAT activities compared with the ORX group. In conclusion, drinking OJ or GJ prevented oxidative stress by enhancing total antioxidant capacity and elevating liver antioxidant enzymes while modulating cardiovascular risk factors.     

Antiproliferative effects of citrus limonoids against human neuroblastoma and colonic adenocarcinoma cells

Limonoids, a family of triterpenoids with putative anticancer properties, occur in fruits as glucosides and aglycones. Both highly purified forms were isolated from seeds and molasses of citrus fruits and tested for toxic effects against two human cancer cell lines, SH-SY5Y neuroblastoma and Caco-2 colonic adenocarcinoma, and a noncancerous mammalian epithelial Chinese hamster ovary (CHO) cells. Viability, as quantified by 3-[4,5-dimethylthiazol- 2-yl]-2,5-diphenyltetrazolium reduction and light microscopy, was shortened significantly (P < 0.001) in cancer cells exposed to aglycones, viz., limonin, nomilin, obacunone, and deacetylnomilin. SH-SY5Y cells were more sensitive than Caco-2 cells to the limonoids, whereas noncancerous CHO cells showed hardly any change in cell numbers or cell morphology. Aglycone toxicity was dose dependent, but below the killing potential of glucosides. This observation correlated with a slower rate of induction of caspase 3/7 activity by aglycones. A flow cytometric analysis of SH-SY5Y cells treated with glucosides and aglycones showed an increased ploidy, which is consistent with enhancing chromosomal abnormalities. The results confirm that limonoids exert a strong multifaceted lethal action against cancer cells, but are relatively ineffective against CHO cells. Of the two, metabolites derived from glucosides are the more likely progenitors of an apoptosis response in situ.