Biomedical subjects
Publications and source records attributed to T Singh.
Six cases of spinal epidural abscess are presented. All patients were young with no predisposing conditions. All were treated with laminectomy and intravenous antibiotics. The patients with no neurological deficit recovered completely, while patients with pre-existing neurological deficit had a poorer outcome. Emphasis is given to early detection and surgical management to prevent irreversible damage to the spinal cord.
PURPOSE: This feasibility study was undertaken to compare the sensitivity of Tc-99m dextran with that of Tc-99m human immunoglobulin G to diagnose ulcerative colitis, and to explore its possible role in disease follow-up. MATERIALS AND METHODS: Twenty-six patients with active disease and six patients in remission underwent serial Tc-99m dextran scanning for as long as 3 hours or more after injection. Eight of the patients with active disease also underwent Tc-99m human immunoglobulin G imaging. RESULTS: Twenty-four of 26 (92%) patients with active ulcerative colitis had a positive result of the Tc-99m dextran study, mainly within 1 hour. In comparison, Tc-99m human immunoglobulin G accumulated abnormally in four of eight (50%) patients and had a relatively poor target localization with high persisting background even after 6 hours. Four of the six patients in remission still had a positive result of the dextran scan, but the abnormal uptake was less than that in the patients with active disease. The disease has recurred already in one of these patients. A patient with pancolitis who was receiving steroid enema therapy had intense uptake of Tc-99m dextran in the ascending colon, probability because it was outside the range of the enema. CONCLUSIONS: Tc-99m dextran is a sensitive and cost-effective agent to diagnose ulcerative colitis, and it may have a role in disease follow-up.
Transforming growth factor-beta1 (TGF-beta1), a multifunctional cytokine with fibrogenic properties, has been implicated in the pathogenesis of the vascular and target organ complications of hypertension. TGF-beta1 may also regulate blood pressure via stimulation of endothelin-1 and/or renin secretion. Herein we explored the hypothesis that circulating levels of TGF-beta1 protein (quantified using a TGF-beta1-specific sandwich ELISA) are correlates of blood pressure levels. This hypothesis was tested in 98 stable end-stage renal disease (ESRD) patients. (The use of ESRD patients as the study cohort eliminates renal function-dependent alterations in circulating levels of TGF-beta1 protein.) In addition, in view of the previously reported correlation among TGF-beta1 DNA polymorphisms and systolic blood pressure, TGF-beta1 codon 25 genotype and alleles were identified in 71 hypertensive subjects and 57 normotensives using amplification refractory mutation system polymerase chain reaction. Our studies demonstrate for the first time that TGF-beta1 levels (209+/-13 ng/mL, mean+/-SEM) are positive correlates (Pearson correlation analysis) of mean arterial pressure (P=0.008), systolic pressure (P=0.02), and diastolic pressure (P=0. 01). We also report that a higher percentage of hypertensives (92%) compared with normotensives (86%) are homozygous for the arginine allele at codon 25. Our observations support the idea that genetically determined TGF-beta1 protein concentrations may play a role in blood pressure regulation in humans.
Data on STDs and sexual practices in commercial sex workers (CSWs) is in general limited in India. Manipur in north-east Indian has a high prevalence of HIV in injecting drug users but the rate in CSWs is not known. The site selected for the study was Moreh, on the Myanmar border of Manipur. One hundred blood samples were collected, 7 from migrants from Myanmar, the remainder from Manipuri women. The HIV seropositivity rate was 12% (95% CI = 5.6-18.4). The age of the women ranged from 15 to 42 (mean = 24.5 years, median 23.7 years). The proportion of HIV positives increased significantly with number of customers per day and number of years in the profession. The HIV prevalence among Injecting drug using CSWs was 9.4 times higher that among non-IDU CSWs. Vaginal discharge was strongly associated with HIV positivity. Effective intervention programmes among CSWs in Manipur to prevent further spread of HIV are strongly indicated by the results of this study.
OBJECTIVE: The use of erythropoietin (EPO) for the amelioration of anemia has dramatically changed the quality of life of the patients with chronic renal failure (CRF). The efficacy of a low dose EPO therapy was assessed in the prospective 6 week trial. METHODS: Assessment of hematological parameters and iron stores was done in 40 patients of CRF: Group A--20 patients of CRF receiving 40 U/kg EPO biweekly for 6 weeks and Group B--20 patients of CRF not receiving EPO. The parameters were studied at the start and at 2, 4 and 6 weeks of the study. RESULTS: A statistically significant rise in mean haemoglobin levels (7.27 +/- 1.26 g/dl to 8.60 +/- 1.66 g/dl); mean packed cell volume (21.4 +/- 4.04% to 25.4 +/- 6.54%) and mean reticulocyte count (1.28 +/- 0.4% to 2.14 +/- 0.86%) was observed on EPO therapy. Patients on EPO developed a significant decline in serum iron, serum ferritin levels, bone marrow iron stores; and a hypochromic-microcytic picture on the peripheral blood film suggestive of iron deficiency. Iron deficiency at the start, chronic infections like tuberculosis and inadequate haemodialysis were identified as causes of hyporesponsiveness to EPO therapy. Low dose EPO therapy was not associated with any major adverse effects. CONCLUSIONS: Low dose EPO (40 U/kg, biweekly) therapy is safe and effective in the management of anaemia of CRF.
BACKGROUND: Nationally, results of renal transplantation in infants are inferior to those in older children and adults. Within the infant group, best results are obtained with adult-sized kidneys (ASKs) rather than size-compatible pediatric kidneys. However, transplantation of ASKs into infants has an increased risk of acute tubular necrosis and graft loss from vascular thrombosis and primary nonfunction. The aim of this study was to define and understand the hemodynamic changes induced by ASK transplantation, so that outcomes of transplantation in infants can be improved. METHODS: Nine hemodynamically stable and optimally hydrated infants were studied under a controlled sedation with cine phase-contrast magnetic resonance at three time periods: before transplantation, 8-12 days after transplantation, and 4-6 months after transplantation. Cross-sectional images of both the infant aorta and the adult transplant renal artery were obtained and blood flow was quantitated. Renal volumes were also obtained, and expected renal artery blood flow based on early posttransplant volume was calculated. In addition, renal artery blood flow was determined in 10 in situ native adult kidneys prior to donor nephrectomy. Supplemental nasogastric or gastrostomy tube feeding was carried out during the blood flow study period to optimize intravascular volume. RESULTS: Mean infant aortic blood flows were 331+/-148 ml/min before transplantation, 761+/-272 ml/ min at 8-12 days after transplantation (P=0.0006 with pretransplant flow), and 665+/-138 ml/min at 4-6 months after transplantation (P=0.0001 with pretransplant flow). Mean transplanted renal artery flows were 385+/-158 ml/min at 8-12 days and 296+/-113 ml/min at 4-6 months after transplantation. Transplanted renal artery flows were less than prenephrectomy in situ donor renal artery blood flow (618+/-130 ml/min; P=0.02 and P=0.0003) and expected normal renal artery blood flow (666+/-87 ml/min; P=0.003 and P=0.001) at both 8-12 days and 4-6 months after transplantation. A 26% reduction in renal volume (P=0.003) occurred between the two postoperative time periods, and this paralleled the decrease in posttransplant renal artery flow. One-year graft and patient survival in the nine infants was 100%. The mean serum creatinine levels at 3, 6, and 12 months were 0.43+/-0.10, 0.48+/-0.15, and 0.49+/-0.16 mg/dl. CONCLUSIONS: This study is the first to quantitatively document the blood flow changes occurring after ASK transplantation in infants. There was a greater than two-fold increase in aortic blood flow after ASK transplantation, and this increase was sustained for at least 4 months and appeared to be driven by the blood flow demand of the ASK. However, actual posttransplant renal artery blood flow was significantly less than normal renal artery flow. Our study suggests that aggressive intravascular volume maintenance may be necessary to achieve and maintain optimum aortic blood flow, so as not to further compromise posttransplant renal artery flow and to avoid low-flow states that could induce acute tubular necrosis, vascular thrombosis, or primary nonfunction.
The life expectancy of children with human immunodeficiency virus (HIV) infection acquired through mother-to-child transmission has important clinical and public health significance. Several sources of population-based surveillance data from New York City, covering 1982 through the end of 1994, were combined to estimate long-term survival of HIV-infected children and age-specific prevalence. HIV incidence among newborns was estimated by applying expected transmission rates to seroprevalence surveys of parturient women and by using back-calculation methods. HIV prevalence in childhood was based on cumulative HIV incidence and cumulative mortality, adjusting for underreporting of death and background causes of death. A modified actuarial method was developed to estimate survival of infected children. At the beginning of 1995, between 1,945 and 3,323 children less than age 13 years were estimated to be living with HIV infection acquired through mother-to-child transmission in New York City. Between 36% and 61% of these infected children were estimated to survive to age 13 years (median survival, 8.6 years to >13 years). A substantial proportion of infected children will survive to adolescence. Thus, it is important that their educational, medical, and other needs be considered. These methods may be useful in other areas in which HIV seroprevalence data among childbearing women and HIV mortality statistics are available.
End-stage renal disease (ESRD) is more frequent in African Americans (blacks) compared to Caucasian Americans (whites). Identification of remediable causes of the increased prevalence has the potential to reduce the excess burden of ESRD. Because renal fibrosis is a correlate of progressive renal failure and a dominant feature of ESRD, and because transforming growth factor-beta 1 (TGF-beta 1) can induce fibrosis and renal insufficiency, we explored the hypothesis that TGF-beta 1 hyperexpression is more frequent in black ESRD patients compared to white ESRD patients. Our postulate was tested by determining circulating levels of TGF-beta 1 protein in the sera of 56 black and 42 white ESRD patients treated by chronic hemodialysis. A solid-phase sandwich enzyme-linked immunosorbent assay, specific for TGF-beta 1, was used to quantify TGF-beta 1 levels in the ESRD cohort. Additional cytokines implicated in tissue repair/remodeling, interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha), were also measured. Our investigation demonstrated a significantly higher concentration of TGF-beta 1 protein but not that of IL-6 or TNF-alpha in blacks compared to whites. Our observation that TGF-beta 1 is hyperexpressed in black ESRD patients suggests a mechanism for the increased prevalence of renal failure (since TGF-beta 1 hyperexpression can result in renal insufficiency in experimental models) among the black population.
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The neuroprotective efficacy of the selective N-type voltage-sensitive calcium channel blocker, SNX-111, was evaluated in spontaneously hypertensive rats subjected to 60 min of focal cerebral ischemia by permanent ligation of the right common carotid artery and temporary occlusion of the right middle cerebral artery. Intravenous infusion of 167 microg/kg per min SNX-111 for 30 min (5 mg/kg), initiated immediately after reperfusion, significantly reduced cortical infarct volumes measured 24 h after the ischemic insult.
Critical care medicine in Canada has evolved into a multidisciplinary service, teaching, and research activity. Pressure on existing funding models for the delivery of health care in Canada is leading to substantial change in the hospital sector. Although not explicitly targeted for change, pre-existing models of critical care delivery will be caught in the acute care services, redesign (that results from the health care restructuring because of the substantial impact that delivering critical care services has on overall hospital budgets). Although starting from different perspectives, the Canadian and American health care systems seem to be converging in their health care redesign principles, with themes such as integration, regionalization, physician payment reform, health care worker redesign, and global budgeting common through the multiplicity of plans being articulated. What critical care will look like in its major domains (service, education, and research) in the year 2001 is difficult to foresee at this time. In this context, therefore, change occurring in Canada's critical care system will be no less challenging than what will occur in the United States or other health care systems. For the resources we have developed for the critically ill patient population to survive health care redesign, we must improve our way of working together internationally, to understand and benchmark best practices and to share ideas for the most effective critical care systems.
Significant uptake and retention of 99Tc(m)-dextran (molecular weight: 81,000) in renal parenchyma was discovered during evaluation of its intravascular use. Renal SPET images confirmed this. This study was designed to evaluate 99Tc(m)-dextran as a renal cortex imaging agent. Stability of parenchymal retention was shown by insignificant outflow at 24 h and by frusemide intervention. Evaluation of the renal parameters of intravenous 99Tc(m)-dextran (n = 71 normal kidneys) and its comparison with 99Tc(m)-DTPA n = 10) and 99Tc(m)-DMSA(III) (n = 23) was undertaken. The early glomerular extraction phase of the renograms of 99Tc(m)-DTPA and 99Tc(m)-dextran appeared identical; parenchymal uptake of 99Tc(m)-dextran continued to increase and reached a near-plateau by 40-60 min. The mean cortex-to-background and cortex-to-liver ratios at 2 h with 99Tc(m)-dextran and 99Tc(m)-DMSA(III) were 14.9 and 9.2, and 16.0 and 8.9, respectively. The target-to-nontarget ratios were similar despite different absolute renal uptake values (12 vs 20% at 2 h) because of faster background clearance of 99Tc(m)-dextran. The mechanism of parenchymal retention of 99Tc(m)-dextran appears to be trapping at the endothelial-epithelial interphase of the glomerulus. Our initial experience suggests 99Tc(m)-dextran is a viable renal parenchyma imaging agent.
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