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Biomedical subjects

N Singh

Publications and source records attributed to N Singh.

At least 379 records · Page 21Linked to original sources
PubMed1995

The effect of active oxygen generated by xanthine/xanthine oxidase on genes and signal transduction in mouse epidermal JB6 cells.

To gain insight into the gene regulation and signal transduction effects of active oxygen in tumour promotion and progression, we studied the effect of active oxygen generated extracellularly by xanthine/xanthine oxidase (X/XO) in promotion-insensitive (P-), promotion-sensitive (P+) and transformed (Tx) mouse epidermal JB6 cells. Active oxygen inhibited growth, particularly of P- cells and increased poly ADPR transferase activity and PKC activity more significantly in P- cells. No phenotypic differences in the distribution pattern of PKC isotypes alpha, beta and gamma were seen in JB6 cells. PKC alpha was expressed abundantly, whereas beta and gamma were not detected. Basal levels of the antioxidant enzymes catalase and CuZn. Superoxide dismutase were higher in P+ and Tx cells. X/XO resulted in an initial decrease in the activity of these enzymes, followed by recovery or transient induction in Tx and P+ cells. X/XO induced c-myc and c-fos expression in JB6 cells, with c-fos induction being more pronounced in P- cells, whereas a biphasic increase in c-jun was seen in P+ cells. These early genes may play a role in proliferation whereas post-translational poly ADP-ribosylation and, perhaps, phosphorylation suggest a genetic-epigenetic mechanism in oxidant tumour promotion and progression.

Animals↗
PubMed1995

Trimethoprim-sulfamethoxazole for the prevention of spontaneous bacterial peritonitis in cirrhosis: a randomized trial.

OBJECTIVE: To assess the efficacy and safety of trimethoprim-sulfamethoxazole for the prevention of spontaneous bacterial peritonitis in patients with cirrhosis and ascites. DESIGN: A randomized controlled trial. SETTING: University-affiliated Veterans Affairs medical center. PATIENTS: 60 consecutive patients with cirrhosis and ascites. INTERVENTIONS: Consecutive patients were randomly assigned to receive either no prophylaxis or trimethoprim-sulfamethoxazole, one double-strength tablet daily, five times a week (Monday through Friday). Patient entry was stratified by serum bilirubin (> 51 mumol/L [> 3 mg/dL]), ascitic fluid protein (< 1 g/dL), and serum creatinine (> 177 mumol/L [> 2 mg/dL]) levels to ensure that high-risk patients would be similarly distributed in the two groups. The median duration of follow-up for the study patients was 90 days. MAIN OUTCOME MEASURES: Spontaneous bacterial peritonitis or spontaneous bacteremia as defined by objective criteria. RESULTS: Spontaneous bacterial peritonitis or spontaneous bacteremia developed in 27% (8 of 30) of patients who did not receive prophylaxis compared with 3% (1 of 30) of patients receiving trimethoprim-sulfamethoxazole (P = 0.025). Overall, infections developed in 9 of 30 patients (30%) not receiving prophylaxis and in 1 of 30 patients (3%) receiving trimethoprim-sulfamethoxazole (P = 0.012). Death occurred in 6 of 30 patients (20%) who did not receive prophylaxis and in 2 of 30 patients (7%) who received trimethoprim-sulfamethoxazole (P = 0.15). Side effects--particularly, hematologic toxicity--could not be attributed to trimethoprim-sulfamethoxazole in any patient. CONCLUSIONS: Trimethoprim-sulfamethoxazole was efficacious, safe, and cost-effective for the prevention of spontaneous bacterial peritonitis in patients with cirrhosis.

Ascites↗
PubMed1995

Induction of apoptosis in chronic myelogenous leukemia lymphocytes by hydroxyurea and adriamycin.

The nature of the cytotoxic effects of the anticancer drugs hydroxyurea, adriamycin, cisplatin and interferon, was studied on lymphocytes obtained from chronic myelogenous leukemia (CML) subjects prior to the commencement of chemotherapy. These drugs appeared to mediate their cytotoxic effects by the process of apoptosis as observed from the morphological changes, i.e., cell shrinkage, chromatin condensation, cell membrane blebbing, and also from the cellular damage and DNA fragmentation into oligonucleosomal ladder of 180-bp multiples, which are all characteristics of apoptotic cell death. The effect was much more marked by hydroxyurea and adriamycin. Maximum sensitivity was seen at 24 h post treatment. Untreated CML lymphocytes cultured for 24 h also showed some apoptosis.

Adult↗
PubMed1995

Modulation of immunogenicity and antigenicity of proteins by maleylation to target scavenger receptors on macrophages.

We have maleylated proteins to target macrophage-specific scavenger receptors and have used this system to study changes in the epitopes and immunogenicity of such proteins. We show that maleylation of diphtheria toxoid (DT) induces targeting to macrophage scavenger receptors and enhances its immunogenicity. DT does not evoke detectable serum Ab responses upon injection as soluble protein. However, maleylated DT (mDT) does generate a significant Ab response. Furthermore, immunization with soluble mDT leads to a better T cell proliferative response in vitro than immunization with DT can generate, thereby demonstrating that maleylation leads to enhanced T cell immunogenicity in vivo. We also find that maleylation disrupts the native B cell epitopes of DT and creates new epitopes, because antisera to DT and mDT do not cross-react. At least some of the new epitopes generated are maleylation specific, because antisera against various maleylated proteins do cross-react. In contrast, maleylation does not significantly modify the repertoire of T cell epitopes generated from DT, because T cells generated by either DT or mDT immunization are cross-reactive, and both DT and mDT can stimulate T cells that are specific for single synthetic DT peptide. Maleylated proteins are better presented in vitro than are their native counterparts, and this enhancement of presentation is blocked by unrelated maleylated proteins. These results suggest that Ags targeted to scavenger receptors on macrophages by maleylation are better presented to T cells and are immunogenic in vivo without adjuvant.

Animals↗
PubMed1995

Treatment of silent ischemia in unstable angina: a randomized comparison of sustained-release verapamil versus metoprolol.

Silent ischemia is a frequent finding in patients with unstable angina and portends a poor prognosis. We compared the efficacy of sustained-release (SR) verapamil and metoprolol in reducing silent ischemia in patients with unstable angina and assessed whether detection of silent ischemia was related to unfavorable outcomes in the contemporary setting of concurrent therapy with heparin and aspirin. Holter monitoring (leads a VF, V2, V5) for the first 72 h was used to assess the frequency and duration of ST-shift episodes. There were 37 patients in the verapamil-SR group and 40 patients in the metoprolol group, with both groups having similar baseline characteristics. There were more episodes of angina in the verampamil-SR group (29 vs. 12, p = 0.05). There was no difference between the two groups in the frequency (51 vs. 49 episodes, p = 0.9) or duration (23 +/- 48 vs. 18 +/- 50 min, p = 0.6) of ST-shift episodes. There were 20 unfavorable in-hospital outcomes distributed equally between the two groups (p = 0.9). Patients with unfavorable outcomes had ST shift more often (50 vs. 28%, p = 0.07) and for a longer duration (40 +/- 69 vs. 13 +/- 38 min, p = 0.03). Patients with ST shift > or = 60 min had a 60% probability of unfavorable outcome compared with 33% for ST shift of 1-59 min duration and 20% for no ST shift (p = 0.04). We conclude that metoprolol appears to reduce symptoms better than verapamil-SR, but no difference in silent ischemia or unfavorable outcomes was seen. Silent ischemia remains a common occurrence in these patients despite heparin and aspirin therapy and its detection continues to have prognostic value.

Adrenergic beta-Antagonists↗
PubMed1995

X-ray fluorescence in the assessment of inter-elemental interactions in rat liver following lead treatment.

Energy dispersive X-ray fluorescence technique was employed to study the interactions of lead (50 and 100 mg/kg body wt) with K, Fe, Cu, Zn, Br and Rb in rat liver. Lead was administered orally to rats daily for dosage periods of 1 and 4 months (short and long terms). Hepatic Fe levels were found to increase significantly with the supplementation of low and high doses of lead for both the treatment periods, although the increase was more pronounced following long-term treatment. The levels of hepatic K, Cu and Br were seen to decrease significantly over both time intervals. Moreover, hepatic Rb contents were lowered with the short-term supplementation of low doses of lead. In contrast, Rb and Zn levels were increased when lead was administered for the longer period at both dose levels.

Animals↗
PubMed1995

Herpes zoster-associated idiopathic thrombocytopenic purpura in a liver transplant recipient: a case report and overview.

Idiopathic (autoimmune) thrombocytopenic purpura has been previously reported as a rare complication in children and in a few adults following chickenpox. We report a case of varicella zoster virus-associated idiopathic thrombocytopenic purpura in an adult liver transplant recipient following dermatomal zoster. Idiopathic thrombocytopenic purpura developed 3 days after the onset of herpes zoster in our patient, with a nadir platelet count of 3000/mm3. The patient was treated with intravenous gamma globulin with recovery of thrombocytopenia after 3 weeks. Transplant clinicians need to be aware that this serious and potentially life-threatening complication may occur with herpes zoster in transplant recipients.

Acyclovir↗
PubMed1995

Suitability of full fat and defatted rice brain obtained from Indian rice for use in food products.

The effect of blending different types of rice bran in wheat flour on the rheological, pasting and baking properties is reported. Dough development time and strength as measured through farinograph decreased with the blending of unstabilized full fat and defatted bran; whereas, blending of stabilized full fat and defatted bran improved the dough strength. Pasting properties revealed an increase in gelatinization temperature and decrease in paste viscosities and set-back values with the blending of various types of rice bran. Bread volume and cookie spread decreased with blending of different types of rice bran; however, the decrease was more pronounced with the defatted bran. Muffin volume improved with the blending of rice bran. Stabilized full fat rice bran up to 20% level and unstabilized full fat or stabilized defatted rice bran up to 10% was found suitable in various food products.

Dietary Fats↗
PubMed1995

The role of NMDA receptor systems in neuropeptide responses to stimulants of abuse.

High doses of stimulants of abuse, such as methamphetamine and cocaine, cause significant increases in the content of neurotension- and dynorphin-like immunoreactivity in the striatum and nucleus accumbens (approximately 200-600% of control) in the rat. These changes in neuropeptide content are caused by stimulation of dopamine D1 receptors and prevented by the glutamate NMDA receptor antagonist, MK 801. Stimulation of the NMDA receptor with N-methyl-D-aspartate results in increases in the neuropeptide levels like that caused by methamphetamine and cocaine. These findings demonstrate that stimulants of abuse profoundly influence neurotensin and dynorphin pathways associated with extrapyramidal and limbic structures by an interaction of activated dopamine D1 and glutamate NMDA receptors.

Animals↗
PubMed1995

Invasive gastrointestinal zygomycosis in a liver transplant recipient: case report and review of zygomycosis in solid-organ transplant recipients.

Zygomycosis is a rare but highly invasive fungal infection that occurs in transplant recipients. We report a case of invasive gastrointestinal zygomycosis that occurred in a heavily immunosuppressed liver transplant recipient 5 days after retransplantation and that presented as gastric perforation. Despite aggressive surgical and antifungal therapy, the patient died. We review 46 cases of invasive zygomycosis in solid-organ transplant recipients. The rhinocerebral form of zygomycosis occurred in 57% of cases; the pulmonary, cutaneous, and disseminated forms each occurred in 13%; the renal form occurred in 2%; and the gastrointestinal form occurred in 2%. The infection ensued a median of 2 months after transplantation (range, 5 days to 8 years). Seventy-six percent of the patients had diabetes or had received antirejection therapy, mainly in the form of corticosteroids, before the onset of zygomycotic infection. The mortality for patients who received antifungal therapy and/or who underwent surgery was 50% for those who had rhinocerebral zygomycosis, none for those who had pulmonary and cutaneous zygomycosis, and 100% for those who had disseminated zygomycosis. Knowledge of the diverse clinical manifestations (including gastrointestinal involvement, as is illustrated by our case) and predisposing factors in transplant recipients with zygomycosis can aid in early recognition of this disease in this patient population.

Adult↗
PubMed1995

An outbreak of infusion-related Klebsiella pneumoniae bacteremia in a liver transplantation unit.

Over a 1-month period, there were five episodes of infusion-related Klebsiella pneumoniae bacteremia in four liver transplantation patients housed in the same ward. Investigation of nursing practices revealed that a common normal-saline bag, to which intravenous (iv) tubing and a stopcock were attached, was used to flush iv catheters. The iv tubing and stopcock were changed at sporadic intervals. Cultures of the normal saline and iv equipment yielded K. pneumoniae, which had the same susceptibility pattern as the patients' isolates. Isolates recovered during the outbreak from the patients and from the iv saline/equipment were of the same strain, as determined by pulsed-field electrophoresis of Xba I-digested genomic DNA. Termination of the practice of flushing iv catheters with a common normal-saline bag halted the outbreak.

Adult↗
PubMed1995

Secondary syphilis: a clinicopathologic study.

BACKGROUND: With the resurgence of syphilis in the HIV era, a greater awareness of the clinicopathologic features of the disease is desirable. This report describes and correlates the clinical and histopathologic features of secondary syphilis seen at a teaching hospital in Delhi, India. METHODS: Forty biopsies of mucocutaneous lesions from 31 consecutive patients with secondary syphilis, seen between September 1987 and January 1991, were studied and the histopathologic findings correlated with the clinical findings. RESULTS: A spectrum of histopathologic changes ranging from a minimal infiltrate to granulomatous inflammation throughout the dermis was seen. The pattern of inflammation correlated well with the type of skin lesion, with macules showing the least and nodules the most prominent changes. The predominant cell type in the infiltrate was the mononuclear cell/lymphocyte. Plasma cells were seen infrequently except in condylomata lata. Endothelial proliferation, the "classical" feature of the histopathology of syphilis was noted infrequently. CONCLUSIONS: The histologic manifestations of secondary syphilis appear to be as varied as the clinical ones. This calls for close interaction between the clinician and the pathologist to correlate the clinical, serologic, and histologic findings to establish the diagnosis of syphilis.

Adolescent↗