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Biomedical subjects

D Kumar

Publications and source records attributed to D Kumar.

At least 91 records · Page 5Linked to original sources
PubMed2001

Kinetics of phase separation in ternary mixtures.

We present detailed results from Monte Carlo simulations of the kinetics of phase separation in ternary mixtures. We focus on the case of ABV mixtures (where V denotes a vacancy) and investigate segregation kinetics resulting from V-mediated dynamics. We provide heuristic arguments for the existence of different morphologies in various parameter regimes. Furthermore, we present comprehensive numerical results for various characteristic features of the domain growth process, e.g., real-space correlation functions, domain-size distribution functions, and growth laws.

Journal Article↗
PubMed2001

Embedded sharp metallic spring in esophagus.

Less than 1% of esophageal foreign bodies are irretrievable by endoscopic techniques. These cases require esophagotomy for removal. The impacted metallic spring with sharp ends (in opposite direction) is reported as esophageal foreign body which required esophagotomy after two failed endoscopic removals. The difficulties encountered during endoscopic maneuver, peculiar shape of foreign body and mode of impaction are discussed.

Child↗
PubMed2001

Kinetics of domain growth in systems with local barriers.

We study domain growth in spin-1 lattice models having nonconserved spin-flip kinetics with local barriers. Our primary motivation is to model the relaxational behavior of physical systems in which molecular motion is impeded by local kinetic barriers. The kinetic constraint is such that a spin from an up (down) state can flip to a down (up) state only via the zero state, which has a higher energy. We examine how the usual curvature-driven domain growth is affected by these local barriers, and whether the single-spin barriers have a collective effect. This paper presents comprehensive numerical results for phase ordering dynamics in this model using Monte Carlo simulations. We demonstrate dynamical scaling for domain-size distribution functions and spatial correlation functions. We also present results for the time dependence of characteristic length scales and autocorrelation functions. The length-scale behavior is interpreted in terms of the random walk of steps on domain boundaries. Furthermore, we present a simple stochastic model to derive an analytic expression for the autocorrelation function, which exhibits a stretched-exponential behavior over an extended regime-in agreement with our numerical simulations.

Journal Article↗
PubMed2001

Tangential views of the articular surface of the distal radius-aid to open reduction and internal fixation of fractures.

Open reduction and internal fixation of comminuted, displaced intra-articular or potentially unstable fractures of the distal radius with plate and screws has increasingly become a favoured treatment. Intra-operative assessment of fixation with the help of an image intensifier has always been difficult because of the anatomy of the distal radius. Imaging of the implants placed as distal as possible to achieve satisfactory fixation often shows the screws to be penetrating the joint. We describe two new radiographic views of the wrist joint, which we used intra-operatively in ten patients undergoing open reduction and internal fixation of distal radius fractures. Screws were thought to have been penetrating the joint in the standard lateral views of all of them and in the standard antero-posterior views of eight of them.However, no screw was seen penetrating the joint in these new views. It was hence possible to place the plate distal enough to enable the screws to engage the sub-chondral bone. We recommend the use of these views in the open reduction and internal fixation of distal radius fractures.

Bone Plates↗
PubMed2001

Partial growth plate fusion caused by burn.

Growth plate fusion is a rare but important complication of burn injury in childhood. Reported cases are all of complete fusion. We present a case of partial fusion of the growth plates secondary to a burn injury, which to our knowledge has not been reported in the literature before. Partial fusion of the growth plate behaves differently as compared with complete fusion, and if treated at an early stage by appropriate surgery limb deformity and long-term disability may be prevented. The importance of early recognition and treatment cannot be overemphasized.

Adult↗
PubMed2001

Increased biogas production using microbial stimulants.

Laboratory studies were undertaken to evaluate the effect of microbial stimulants Aquasan and Teresan, on biogas yields from cattle dung and combined residues of cattle dung and kitchen waste, respectively. The addition of single dose of Aquasan at the rate of 10, 15 and 20 ppm to cattle dung on the first day of incubation resulted in increased gas yields ranging between 45.1 and 62.1 l/kg dry matter. Subsequent addition of Aquasan at 15 and 20 ppm dosage after a period of 15 days increased the gas yields by 15-16%. The gas production was found to be optimum at a dosage level of 15 ppm and was 39% and 55% higher with single and dual additions, respectively, than untreated cattle dung. In another bench scale study (1:1 dry matter) the addition of Teresan at 10 ppm concentration to the mixed residues of cattle dung and kitchen wastes at different solids concentration, produced 34.8% more gas (272.4 l/kg d.m.) than the uninoculated mixture at 15% TS concentration (202.4 l/kg d.m.).

Anaerobiosis↗
PubMed2001

Distribution of cells bearing B-cell alloantigen(s) in North Indian rheumatic fever/rheumatic heart disease patients.

Numerous investigators have developed monoclonal antibodies against B-cell alloantigen(s) of rheumatic fever. However, the developed monoclonals do not have the same significance in all the populations. We have developed a battery of monoclonals against B-cell alloantigens of North Indian rheumatic fever patients. In the present study, we have used these monoclonals to examine the frequency of rheumatic antigens in 30 patients with recurrence of rheumatic activity (RRA), 30 of rheumatic heart disease (RHD) patients and 50 controls using alkaline phosphatase anti-alkaline phosphatase (APAAP) technique. These patients were examined at the time of registry and after three months follow up. RRA patients showed higher percentage of lymphocyte positive as compare to RHD and controls. Interestingly, on follow-up RRA patients showed significant decline in positive lymphocyte as compare to first visit whereas no such change was observed in RHD patients. There were 90-93% of RRA and RHD patients positive with these monoclonals. A significant age variation of rheumatic cells was also noticed in all groups of rheumatic patients. We conclude that monoclonals raised from the same ethnic population are highly specific and cost effective to use them to develop an easy field test system such as APAAP, to identify the individual at risk, to develop rheumatic fever. It is also suggested that the alloantigen marker may persist through out life and gets activated after recurrence of the disease.

Adolescent↗
PubMed2001

Autosomal dominant congenital superior oblique palsy.

PURPOSE: We describe a mother and all her offspring with congenital superior oblique palsy (CSOP), and a father and all his sons with unilateral CSOP. We discuss the inheritance pattern in our pedigrees and compare it with previous reports. METHOD: All available family members were examined. The prism cover test was performed. Ocular movements were examined in all positions of gaze and where possible a Hess chart plotted. Lang and TNO stereotests were used to determine the stereo-acuity. The results of these tests combined with the Bielschowsky head tilt test (BHTT) were used to confirm the diagnosis of superior oblique palsy. The condition was classified as congenital if it presented early based on history or the observation of old photographs and in the absence of a causative factor. RESULTS: The affected members of family A consist of a father and his three sons with unilateral CSOP. His daughter had a mild weakness of her left inferior and superior rectus muscle. One of his sons was asymptomatic and only recognised on screening of the family for the study. The affected members of family B consist of a mother and her younger daughter with unilateral CSOP and her older daughter with bilateral CSOP. She had no other children. CONCLUSIONS: Our families demonstrate what is probably an autosomal dominant form of CSOP. It is possible that hereditary CSOP is more common than previously reported.

Adult↗
PubMed2001

Food hypersensitivity and irritable bowel syndrome.

Irritable bowel syndrome is a common condition but its pathophysiology remains poorly understood. Many irritable bowel syndrome patients give a history of food intolerance, but data from dietary elimination and re-challenge studies are inconclusive. Multiple aetio-pathological mechanisms have been postulated. The gut has an extensive immune system but current understanding of processing of food antigens in health and disease is limited. There is no clinically useful marker available to test for food hypersensitivity in irritable bowel syndrome. Researchers have employed both skin tests and serum immunoglobulins (IgG and IgE) as markers of food hypersensitivity in various disorders including irritable bowel syndrome, but published data are equivocal. In this article, the evidence for the role of food hypersensitivity in irritable bowel syndrome is reviewed and, based on the available data, a possible pathophysiological hypothesis has been formulated.

Allergens↗
PubMed2001

Use of ursodeoxycholic acid in liver diseases.

Ursodeoxycholic acid is currently the only established drug for the treatment of chronic cholestatic liver diseases. It has cytoprotective, anti-apoptotic, membrane stabilizing, anti-oxidative and immunomodulatory effects. Prolonged administration of ursodeoxycholic acid in patients with primary biliary cirrhosis (PBC) is associated with survival benefit and a delaying of liver transplantation. There is evidence that it might even prevent progression of the histologic stage of PBC. It also has a beneficial effect on primary sclerosing cholangitis, intrahepatic cholestasis of pregnancy, liver disease associated with cystic fibrosis, chronic graft versus host disease, total parenteral nutrition associated cholestasis and various pediatric cholestatic liver diseases. In the present review the current knowledge about the mechanisms of the action and role of ursodeoxycholic acid in the treatment of various liver diseases has been discussed.

Cholagogues and Choleretics↗
PubMed2001

Cytoprotective and immunomodulatory properties of Geriforte, a herbomineral preparation, in lymphocytes.

The study was designed to determine the cytoprotective and immunomodulatory properties of Geriforte, an indigenous herbomineral compound, using lymphocytes as a model system. The possible involvement of free radicals and the ability of Geriforte to inhibit the oxidative process induced by tert-butylhydroperoxide (tert-BHP) was also investigated. The production of free radicals (evaluated by fluorescent probe fluorescein-diacetate), level of malondialdehyde (MDA, as index of lipid peroxidation), and levels of anti-oxidants--reduced glutathione (GSH) and glutathione peroxidase (GPx) were determined. There was an increase in cytotoxicity and apoptosis significantly in the presence of tert-BHP (100 microM) over control. Addition of tert-BHP resulted in a marked increase in free radical production and MDA level with a concomitant decrease in GSH level in lymphocytes. Geriforte supplementation reduced cytotoxicity and apoptosis induced by tert-BHP. Further, Geriforte inhibited tert-BHP induced lipid peroxidation and maintained higher anti-oxidant levels. tert-BHP significantly inhibited the lymphocyte proliferation stimulated by mitogens (Lipopolysaccharide/Concanavalin A) and enhanced DNA fragmentation. Geriforte relieved the inhibitory effect of tert-BHP on lymphocyte proliferation and decreased DNA fragmentation appreciably. The results indicate that Geriforte possesses cytoprotective and immunomodulatory properties which could be due to its anti-oxidant activity.

Adjuvants, Immunologic↗
PubMed2001

Apoptosis in adriamycin cardiomyopathy and its modulation by probucol.

The dose-dependent cardiomyopathy and heart failure due to adriamycin have been shown to be due to increased oxidative stress and loss of myocytes. We examined the incidence of myocardial apoptosis as well as changes in the expression of apoptotic regulatory gene products in an established animal model of adriamycin cardiomyopathy. Rats were treated with adriamycin (cumulative dose, 15 mg/kg), and the hearts were examined for apoptosis as well as expression of Bax, caspase 3, and Bcl-2 at 0, 4, 10, 16, and 21 days after the treatment. A significant increase in the incidence of apoptosis was seen at 4 days, followed by a decline at 10 and 16 days of posttreatment. At 21 days, the number of apoptotic cells increased again and included cells of the conducting system. Expression of Bax corresponded to these biphasic changes, whereas the converse was true for the expression of Bcl-2. The latter peaked at 10 days followed by a decline at 16 and 21 days. The Bax/Bcl-2 ratio also correlated with the incidence of apoptosis. Expression of caspase 3 correlated with increased apoptosis, but only at early time points. Probucol (cumulative dose, 120 mg/kg), a known antioxidant as well as promoter of endogenous antioxidants, significantly reduced the incidence of apoptosis as well as expression of Bax. Adriamycin-induced hemodynamic changes were also prevented by probucol. These data suggest that adriamycin-induced apoptosis is mediated by oxidative stress and may play a role in the development of heart failure.

Animals↗
PubMed2001

Postischemic apoptosis and functional recovery after angiotensin II type 1 receptor blockade in isolated working rat hearts.

OBJECTIVE: To determine whether chronic angiotensin (AngII) type I receptor (AT1R) blockade inhibits cardiomyocyte (CM) apoptosis and attenuates left ventricular (LV) dysfunction after ischemia-reperfusion (IR) in the isolated working rat heart. METHODS: Postischemic recovery of LV developed pressure, the apoptotic index (terminal deoxynucleotidyl transferase (TdT)-mediated dUTP in situ nick end labeling or TUNEL assay), and changes in expression of apoptotic markers Bcl-2, Bax, p53 and caspase-3 (Western immunoblots) were measured after IR (50 min aerobic perfusion; 25 min global ischemia; 40 min reperfusion) in working rat hearts that were randomized to five groups of six each along 1 week or 3 week pretreatment arms: sham (no drug, no perfusion); no drug, aerobic perfusion; and oral AT1R blockers losartan (30 mg/kg per day) or UP269-6 (3 mg/kg per day), or no drug before IR. RESULTS: Compared to the no drug group after IR, losartan (not UP269-6) preserved functional recovery in 1 and 3 week groups. However, both losartan and UP269-6 reduced the apoptotic index and normalized the increase in Bax, decrease in Bcl-2 and increase in p53 and caspase-3 after IR. A bell-shaped relation between apoptosis and functional recovery after IR was flattened by AT1R blockade. CONCLUSION: The results indicate that IR is associated with LV dysfunction and CM apoptosis involving activation of p53, caspase-3, and increased Bax/Bcl-2 ratio in the working rat heart. Importantly, chronic AT1R blockade inhibited the apoptosis and changes in expression of the markers without improving functional recovery, implying that decrease in apoptosis does not necessarily translate into decreased LV dysfunction.

Angiotensin Receptor Antagonists↗
PubMed2001

Lymphatic filariasis of the ovary and mesosalpinx.

We report 2 cases of filariasis, one in the ovary and the other in the mesosalpinx. In the first case, the patient underwent panhystrectomy and in the second case, right ovarian cystectomy with right salpingectomy were performed under general anaesthesia. Histopathology showed adult filarial worms in the dilated lymphatics of the right ovary, in the first case and in the mesosalpinx, in the second case. Both patients presented with complaints related to gynecological problems and not filariasis. Reports of filariasis in the literature and possible treatments and prevention strategies are also discussed.

Abdominal Pain↗
PubMed2001

Diagnostic accuracy of simpson atherectomy catheter biopsy in detecting pancreaticobiliary malignancy.

OBJECTIVE: Impressive advances have been made in imaging the biliary tree by various modalities in the last few decades. However, the histological diagnosis of stenosing lesions in the biliary ductal system has remained difficult and unreliable. Application of Simpson atherectomy catheter biopsy in obtaining accurate histological diagnosis of bile duct lesions appears promising. The purpose of our study was to determine the clinical accuracy of the Simpson atherectomy catheter biopsy in the evaluation of bile duct strictures. METHODS: A retrospective study of medical records of patients who underwent bile duct biopsy by atherectomy catheter was conducted between 1991 and 1999. During this period, 53 patients underwent 56 endoluminal bile duct biopsies with an atherectomy catheter as part of an obstructive jaundice workup. Histological diagnosis on biopsy was confirmed by subsequent surgical biopsy and/or clinical follow-up. RESULTS: Fifty-four (96%) bile duct biopsies were technically successful in terms of yielding a histological diagnosis. Thirty-one of the 56 (55%) biopsy specimens were positive for malignancy (27 adenocarcinoma, two islet cell-carcinoids, one small cell carcinoma, and one malignant lymphoma). Four (7%) were read by the pathologist as highly suspicious for malignancy, and 19 (34%) specimens were considered negative for malignancy. Sensitivity of atherectomy catheter endoluminal biliary biopsy in this study was 97% with a specificity of 100%. In addition, the positive predictive and negative predictive values of this modality were 100% and 93%, respectively. CONCLUSIONS: Endoluminal bile duct biopsy by Simpson atherectomy catheter appears to be a highly sensitive and specific method for establishing histological diagnosis of stenosing lesions in the biliary ductal system.

Adult↗
PubMed2001

Intestinal luminal pH in inflammatory bowel disease: possible determinants and implications for therapy with aminosalicylates and other drugs.

Measurements of luminal pH in the normal gastrointestinal tract have shown a progressive increase in pH from the duodenum to the terminal ileum, a decrease in the caecum, and then a slow rise along the colon to the rectum. Some data in patients with ulcerative colitis suggest a substantial reduction below normal values in the right colon, while limited results in Crohn's disease have been contradictory. Determinants of luminal pH in the colon include mucosal bicarbonate and lactate production, bacterial fermentation of carbohydrates and mucosal absorption of short chain fatty acids, and possibly intestinal transit. Alterations in these factors, as a result of mucosal disease and changes in diet, are likely to explain abnormal pH measurements in inflammatory bowel disease (IBD). It is conceivable that reduced intracolonic pH in active ulcerative colitis impairs bioavailability of 5-aminosalicylic acid from pH dependent release formulations (Asacol, Salofalk) and those requiring cleavage by bacterial azo reductase (sulphasalazine, olsalazine, balsalazide), but further pharmacokinetic studies are needed to confirm this possibility. Reports that balsalazide and olsalazine may be more efficacious in active and quiescent ulcerative colitis, respectively, than Asacol suggest that low pH may be a more critical factor in patients taking directly pH dependent release than azo bonded preparations. Reduced intracolonic pH also needs to be considered in the development of pH dependent colonic release formulations of budesonide and azathioprine for use in ulcerative and Crohn's colitis. This paper reviews methods for measuring gut pH, its changes in IBD, and how these may influence current and future therapies.

Anti-Inflammatory Agents↗
PubMed2001

Myocardial oxidative stress and antioxidants in hypertension as a result of nitric oxide synthase inhibition.

Rats were made hypertensive by the administration of the nitric oxide synthase inhibitor nitro-L-arginine (LNA, 2.74 mmol/L) in drinking water for 7 d. Hearts from hemodynamically assessed animals were analyzed for lipid peroxidation (LPO), gamma-glutamylcysteine-synthetase (gamma-GCS), glutathione disulfide reductase (GR), glutathione peroxidase (GSHPx), catalase (CAT), superoxide dismutase (SOD), and total radical trapping potential (TRAP) activities. LNA treatment increased the mean arterial blood pressure by 46% and the heart rate by 22% without changing plasma renin activity. LNA treatment resulted in a 30% increase in LPO. gamma-GCS was reduced by 48% and GR by 36% in the cardiac tissue of hypertensive rats as compared to controls. The activity of nonselenium GSHPx was reduced by 27%, and selenium-dependent GSHPx activity in the heart was not affected by LNA treatment. In hypertensive rats, SOD activity was increased by 16%, and CAT was decreased by 46%. TRAP was lower (27%) in the myocardium of hypertensive rats than in that of controls. These data suggest that LNA-induced hypertension is associated with increased myocardial oxidative stress.

Animals↗