Influence of heat stress on the reactivity of isolated chicken carotid artery to vasoactive agents

Cerebral ischaemia is considered to be an important cause of central nervous system dysfunction in heat stress. We hypothesized that heat stress would alter the reactivity of isolated carotid artery to vasoactive agents. Carotid arteries were isolated from broiler chickens maintained either at 23-24 degrees C with 55-65% humidity (control conditions) or exposed to 40 +/- 1 degrees C with 35% humidity for 4 h (heat stress). Contractions were elicited with vasoconstrictors such as 5-HT, phenylephrine, guanfacine and CaCl(2) (K(+)-depolarized) in endothelium-denuded arterial rings. Heat stress significantly increased the potency of 5-HT, but had no effect on the sensitivity of the vessel to phenylephrine or guanfacine. In contrast, it markedly decreased the potency and efficacy of CaCl(2). Vasodilator responses to ACh (endothelium-intact) and sodium nitroprusside (endothelium-denuded), however, were unaffected. Although cyclopiazonic acid (10 microm) significantly decreased 5-HT responses in both the conditions, the agonist was still more potent in heat stress. Extracellular Ca(2)(+) removal had no effect on contractions caused by 5-HT in control conditions, but it significantly decreased the agonist potency in heat stress. Interestingly, nifedipine (1 microm) markedly inhibited 5-HT-induced contractions both in control conditions and in heat stress, implying an inhibitory effect on both Ca(2)(+) influx and release. Thus, nifedipine had a markedly greater inhibitory effect on 5-HT-induced contractions in heat stress compared with control conditions. The results suggest that heat stress increased the vasoconstrictor responses to 5-HT by a mechanism that involved extracellular Ca(2)(+) influx through nifedipine-sensitive L-type calcium channels.     

Evaluation of the diagnostic potential of region of deletion-1-encoded antigen culture filtrate protein-10 in pulmonary tuberculosis

The ability of region of deletion-1 (RD-1)-encoded culture filtrate protein-10 (CFP-10) to supplement the sensitivity of 38-kDa antigen was studied using enzyme-linked immunosorbent assay in pulmonary tuberculosis (TB) patients and controls. The sensitivities for individual antigens ranged from 50% to 60%, and the specificity was 100% for immunoglobulin (Ig) G alone. When IgA results were added to IgG, the sensitivity increased. On combination of the isotype results, sensitivity increased to 61.8% and 57.2% (for 38-kDa antigen and CFP-10), respectively, and specificity changed to 98.8% and 99.4% for 38-kDa and CFP-10, respectively. Combination of results of both the antigens gave 82.4% sensitivity in smear-positive and culture-positive group, and 98.1% specificity. In smear-negative and culture-positive group, the sensitivity was 66.7%. In smear-negative and culture-negative cases, a sensitivity of 65.6% was obtained. This study demonstrates that the use of RD-1-encoded CFP-10 enhances the sensitivity of 38-kDa antigen and can be a useful diagnostic marker in TB.     

Prolonged effects of DPP-4 inhibitors on steato-hepatitic changes in Sprague–Dawley rats fed a high-cholesterol diet

Objective

Sitagliptin and other dipeptidyl peptidase (DPP)‐4 inhibitors/gliptins are antidiabetic drugs known to improve lipid profile, and confer anti‐inflammatory and anti‐fibrotic effects, which are independent of their hypoglycemic effects. However, in our previous short-term (35 days) studies, we showed that sitagliptin accentuates the hepato-inflammatory effects of high dietary cholesterol (Cho) in male Sprague–Dawley rats. Since most type 2 diabetics also present with lipid abnormalities and use DPP-4 inhibitors for glucose management, the present study was conducted to assess the impact of sitagliptin during long-term (98 days) feeding of a high Cho diet. An additional component of the present investigation was the inclusion of other gliptins to determine if hepatic steatosis, necro‐inflammation, and fibrosis were specific to sitagliptin or are class effects.

Methods

Adult male Sprague–Dawley rats were fed control or high Cho (2.0%) diets, and gavaged daily (from day 30 through 98) with vehicle or DPP-4 inhibitors (sitagliptin or alogliptin or saxagliptin). On day 99 after a 4 h fast, rats were euthanized. Blood and liver samples were collected to measure lipids and cytokines, and for histopathological evaluation, determination of hepatic lesions (steatosis, necrosis, inflammation, and fibrosis) using specific staining and immunohistochemical methods.

Results

Compared to controls, the high Cho diet produced a robust increase in NASH like phenotype that included increased expression of hepatic (Tnfa, Il1b, and Mcp1) and circulatory (TNFα and IL-1β) markers of inflammation, steatosis, necrosis, fibrosis, and mononuclear cell infiltration. These mononuclear cells were identified as macrophages and T cells, and their recruitment in the liver was facilitated by marked increases in endothelium‐expressed cell adhesion molecules. Importantly, treatment with DPP‐4 inhibitors (3 tested) neither alleviated the pathologic responses induced by high Cho diet nor improved lipid profile.

Conclusions

The potential lipid lowering effects of DPP-4 inhibitors were diminished by high Cho (a significant risk factor for inducing liver damage). The robust inflammatory responses induced by high Cho feeding in long-term experiment were not exacerbated by DPP-4 inhibitors and a consistent hepatic inflammatory environment persisted, implying a prospective physiological adaptation.

     

Design and synthesis of pH-responsive polymeric carriers that target uptake and enhance the intracellular delivery of oligonucleotides.

The delivery of biomolecular therapeutics that function intracellularly remains a significant challenge in the field of biotechnology. In this report, a new family of polymeric drug carriers that combine cell targeting, a pH-responsive membrane-disruptive component, and serum-stabilizing polyethylene glycol (PEG) grafts, is shown to direct the uptake and endosomal release of oligonucleotides in a primary hepatocyte cell line. These polymers are called encrypted polymers and are graft terpolymers that consist of a hydrophobic, membrane-disruptive backbone onto which hydrophilic PEG chains have been grafted through acid-degradable linker acetal linkages. In this report, the ability of the encrypted polymers to deliver rhodamine-labeled oligonucleotides or PEG-FITC (a model macromolecular drug) (5 kDa) into the cytoplasm of hepatocytes was investigated by fluorescence microscopy. Two new encrypted polymer derivatives (polymers E2 and E3) were synthesized that contained lactose for targeting to hepatocytes. Polymer E2 also has PEG-FITC conjugated to it, as a model macromolecular drug, and polymer E3 contains a pendant hexalysine moiety for complexing oligonucleotides. The results of the fluorescence microscopy experiments show that the encrypted polymers direct vesicular escape and efficiently deliver oligonucleotides and macromolecules into the cytoplasm of hepatocytes.     

Antihypertensive activity of captopril (SQ 14,225), an orally active inhibitor of angiotensin converting enzyme in conscious two-kidney perinephritic hypertensive dogs

Conscious dogs made hypertensive by wrapping both kidneys with cellophane were treated daily with a single dose of captopril (31 mg/kg p.o.), an inhibitor of the angiotensin converting enzyme, or with placebo (lactose, 31 mg/kg p.o.) for a period of 13 weeks. Blood pressures were recorded indirectly from a forepaw by using a Roche ultrasonic pressure transducer (Arteriosonde). Treatment with captopril resulted in decreases in blood pressure (25-30 mm Hg) that were maximal at 3 to 6 hr with no associated changes in heart rate. The captopril-induced hypotensive effect was maintained throughout the 13-week treatment period, and after the termination of captopril dosing, pressure rose slowly over the next 72 hr to a level not significantly different from placebo-treated dogs. Plasma renin activity (PRA) in the hypertensive dogs at the time treatment was initiated was not different from the same animals when they were normotensive. In captopril-treated animals, PRA increased 3- to 4-fold after each dose of the drug was given, reaching a maximum at 3 to 6 hr, a time corresponding to the maximal blood pressure decrease. PRA gradually declined but did not reach control levels before the next dose of captopril was administered. In animals treated with placebo, PRA remained at levels not significantly different from normotensive dogs during the entire treatment period. After termination of captopril administration, PRA slowly returned to pretreatment levels; the return of PRA paralleled the recovery of blood pressure. The results indicate that captopril is effective in reducing blood pressure for an extended period of time in a hypertensive model in which the level of activity of the renin angiotensin system is not elevated.     

Relationship Between Glycine Transporter 1 Inhibition as Measured with Positron Emission Tomography and Changes in Cognitive Performances in Nonhuman Primates

Several lines of evidence suggest that schizophrenia is associated with deficits in glutamatergic transmission at the N-methyl-d-aspartate (NMDA) receptors. Glycine is a NMDA receptor co-agonist, and extracellular levels of glycine are regulated in the forebrain by the glycine type-1 transporters (GlyT-1). GlyT-1 inhibitors elevate extracellular glycine and thus potentiate NMDA transmission. This mechanism represents a promising new avenue for the treatment of schizophrenia. Here, the recently introduced positron emission tomography radiotracer [11C]GSK931145 was used to quantify the relationship between occupancy of GlyT-1 by a GlyT-1 inhibitor, Org 25935, and its impact on spatial working memory performances in rhesus monkeys. The effect of Org 25935 on working memory was assessed both in control conditions and during a state of relative NMDA hypofunction induced by ketamine administration, at a dose selected for each animal to reduce task performance by about 50%. Under control conditions, Org 25935 had no effect on working memory at GlyT-1 occupancies lower than 75% and significantly impaired working memory at occupancies higher than 75%. Under ketamine conditions, Org 25935 reversed the deficit in working memory induced by ketamine and did so optimally in the 40–70% GlyT-1 occupancy range. The results confirm the efficacy of this mechanism to correct working memory deficits associated with NMDA hypofunction. These data also suggest the existence of an inverted-U dose–response curve in the potential therapeutic effect of this class of compounds.     

Chronic conjunctivitis due to Mycobacterium tuberculosis

To report the clinical characteristics and treatment outcome in six patients with chronic conjunctivitis due to Mycobacterium tuberculosis. In this retrospective observational case series, all patients with a diagnosis of conjunctival tuberculosis seen in our clinics between January 2000 and January 2010 were reviewed. The clinical presentation, diagnostic investigations and response to medical therapy and outcomes were analyzed. Six patients (age range 15–47 years) were diagnosed with conjunctival tuberculosis. The mean duration from onset of symptoms to diagnosis was 6.5 months (range 1–12 months). Of the six patients, two had ulceration, one had a nodulo-ulcerative lesion, one had bilateral nodular epibulbar masses, and one had a hypertrophied papillary lesion. Systemic signs of tuberculosis were noted in two patients—pleural effusion in one and preauricular and submandibular lymph node involvement in the other. All patients had resolution of symptoms after treatment with four-drug anti-tuberculosis therapy (ATT). None had ocular or systemic recurrences after completion of ATT. Tuberculosis of the conjunctiva can have varied clinical presentation. Although a rare entity, it should be suspected in non-responding chronic conjunctivitis. A high index of suspicion and clinical examination aided by appropriate microbiological and histopathological testing can help in early diagnosis and management.     

Neurosyphilis: MRI features and their phenotypic correlation in a cohort of 35 patients from a tertiary care university hospital

Introduction

The clinical and MR imaging features of neurosyphilis are highly varied. In this study, we describe the spectrum of the imaging findings in patients with neurosyphilis.

Methods

The MR imaging observations of 35 patients diagnosed to have neurosyphilis on the basis of cerebrospinal fluid reactive for the Venereal Disease Research Laboratory test were reviewed.

Results

All the 35 patients, including four with human immunodeficiency virus coinfection, met the CDC diagnostic criteria for neurosyphilis. Patients were classified into three groups: (1) neuropsychiatric, (2) meningovascular, and (3) myelopathic, based on the dominant clinical manifestations. Fourteen patients with neuropsychiatric manifestations showed diffuse cerebral atrophy (14), parenchymal signal changes in the mesial temporal region (2) and temporal and basifrontal regions (1), infarcts (3), and nonspecific white matter changes (3). Eleven patients with meningovascular form showed infarcts (6), diffuse cerebral atrophy (3), signal changes in the mesial temporal region (3), sulcal exudates (1), progressive multifocal leukoencephalopathy (1), and a mass surrounding the carotid sheath (1). Spine imaging in ten patients with myelopathy showed long-segment signal changes (5), contrast enhancement (2), and dorsal column involvement (2). Three of these patients had normal spinal study. Six patients in the myelopathic group also underwent brain MRI that showed signal changes in the temporal region (2) and frontal region (1), multiple infarcts (1), and enhancing hypothalami (1). Three patients had normal study.

Conclusion

MRI abnormalities in neurosyphilis are protean and mimic of many other neurological disorders and thus require a high index of suspicion to reduce diagnostic omissions.