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Biomedical subjects

K Singh

Publications and source records attributed to K Singh.

At least 253 records · Page 14Linked to original sources
PubMed1997

Evaluation of Nd:YAG laser membranectomy in blocked tubes after glaucoma tube-shunt surgery.

PURPOSE: To determine the effectiveness of Nd:YAG laser membranectomy for reopening blocked glaucoma tube shunts and maintaining the patency over time. METHODS: We reviewed retrospectively the records of 13 patients (13 eyes) who, during the period January 1990 through June 1996, underwent Nd:YAG laser membranectomy in an attempt to reopen a blocked glaucoma tube shunt. Intraocular pressure and tube patency were evaluated at each follow-up visit. RESULTS: Nd:YAG laser membranectomy effectively opened the blocked glaucoma tube shunts in 11 (84.6%) of 13 eyes. Two tubes could not be reopened. Reblockage occurred in seven eyes (53.8%) within the first 11 weeks; four tubes (30.8%) remained patent through follow-up periods of 39, 82, 106, and 169 weeks. Postlaser complications were moderate anterior chamber reaction in four eyes (30.8%), hyphema in two eyes (15.4%), corneal edema in two eyes (15.4%), pressure spike in one eye (7.7%), and shallow anterior chamber in one eye (7.7%). CONCLUSIONS: Nd:YAG laser membranectomy is effective in reopening blocked glaucoma tube shunts but is associated with a relatively high rate of subsequent reblockage in the initially successful cases.

Aged↗
PubMed1997

A study on the effects of Norplant implantable contraceptive on lipid, lipoprotein, and apolipoprotein metabolism in Singaporean women.

The Norplant subdermal implants system is rapidly becoming acceptable as a contraceptive system all over the world. Earlier studies in Singapore indicated that the implants do not appear directly contributory to cardiovascular risk. However, extraneous environmental effects could have contributed to the observed changes. In this study, when nonsteroid copper intrauterine device (IUD) users were used as control, we have shown that the findings are in concordance with the results of the earlier studies. There was a decrease in serum triglycerides, total cholesterol, and HDL and LDL cholesterol over the period of study. However, despite these changes the HDL cholesterol/total cholesterol ratio remained stable and was above 0.200. As regards apolipoprotein, there was generally a significant full in apolipoprotein AI, AII, and B. As a result, the apolipoprotein AI/AII ratio showed a significant decrease in the first 3 months before increasing close to its preinsertion value at 2 years. Similarly, the apolipoprotein AI/B ratio also stabilized at the end of 2 years. This study thus confirms our earlier findings that Norplant implants do not appear directly contributory to cardiovascular risk.

Adult↗
PubMed1997

Effects of temperature and concentration on bovine lens alpha-crystallin secondary structure: a circular dichroism spectroscopic study.

Elucidation of the structure of alpha-crystallin, the major protein in all vertebrate lenses, is important for understanding its role in maintaining transparency and its function in other tissues under both normal and pathological conditions. Progress toward a unified consensus concerning the tertiary and quaternary structures of alpha-crystallin depends, in part, on an accurate estimation of its secondary structure. For the first time, three algorithms, SELCON, K2D and CONTIN were used to analyze far ultra-violet circular dichroism (UV-CD) spectra of bovine lens alpha-crystallin to estimate the secondary structure and to determine the effects of temperature and concentration. Under all experimental conditions tested, the analyses show that alpha-crystallin contains 14% alpha-helix, 35% beta-sheet and the remainder, random coil and turns. The results suggest that alpha-crystallin is best classified as a mixed protein. In addition, increased temperature and concentration of alpha-crystallin result in increased alpha-helices with a compensatory decrease in beta-sheets. Such structural alterations in alpha-crystallin may be functionally important during terminal differentiation of the lens fiber cells that is accompanied by increased protein concentrations and its role as a chaperone-like protein.

Animals↗
PubMed1997

A comparison of the clinical performance, contraceptive efficacy, reversibility and acceptability of Norplant implants and Ortho Gynae T380 intrauterine copper contraceptive device.

In this comparative study, the five-year continuity rate of 53.7% in the Norplant implants group was comparable to that of 52.7% in the copper IUD group. The difference was not statistically significant. Only one accidental pregnancy occurred during the five years of copper IUD use. Desire for future pregnancy was the main reason for removal in the Norplant implants group (35.9%) while expulsion of the IUD (13.2%) was the main reason for removal of the copper IUD. Menstrual disturbance was not a major side-effect in either group. The post-removal conception rates of 78.6% in the Norplant implants group and 75.0% in the copper IUD were good and comparable. Both the Norplant implants and copper IUD are acceptable and effective contraceptive methods in Singapore.

Adult↗
PubMed1997

Sclerotherapy in noncirrhotic portal fibrosis.

Endoscopic sclerotherapy has emerged as an effective and safe mode of treatment for long-term management of esophageal varices due to cirrhosis of liver and extrahepatic portal venous obstruction. There are few studies that have evaluated the role of sclerotherapy in the management of esophageal varices in patients with noncirrhotic portal fibrosis (NCPF). We report our results of long-term sclerotherapy in patients with NCPF. Seventy-two consecutive patients (men 29, women 43; age 32.9 +/- 11.8 years) with recurrent variceal bleeding due to NCPF were entered into the sclerotherapy program. Forty-eight patients received intravariceal absolute alcohol and 24 patients received intravariceal sodium tetradecyl sulfate (STD). Variceal obliteration was achieved in 65 (90.3%) patients with a mean of 5.7 +/- 3.0 (range 1-14) sessions. These patients were followed-up for a mean of 21.4 +/- 20.4 (range 1-96) months. Thirteen (17.3%) patients had episodes of upper gastrointestinal bleeding during sclerotherapy. Rebleed after obliteration was seen in 6 (9.2%) patients. Sclerotherapy was associated with a significant reduction in bleeding rate (bleeds per month per patient) during sclerotherapy and after obliteration of varices as compared to presclerotherapy period (P < 0.000001 for both). Recurrence of esophageal varices after obliteration was seen in 9 (13.9%) patients with reobliteration of varices in five patients in whom sclerotherapy was attempted. Complications including esophageal ulcer and stricture formation were seen in 18 (25%) and 4 (5.6%) patients respectively; strictures were restricted to patients who received absolute alcohol. Two (2.77%) patients died of massive upper gastrointestinal bleed during follow-up. We conclude that sclerotherapy is an effective and safe modality in the prevention of variceal bleeds in patients with NCPF.

Adult↗
PubMed1997

HER-2/neu expression in pancreatic adenocarcinoma: relation to tumor differentiation and survival.

HER-2/neu expression in pancreatic adenocarcinoma has been inconsistently reported and has not been fully evaluated with respect to histologic grade and tumor grade heterogeneity. We studied HER-2/neu expression in a series of 79 primary pancreatic carcinomas using immunohistochemical methods, with expression scored for each histologic grade represented in each tumor. We found significantly lower expression of HER-2/neu in poorly differentiated (PD) portions of tumors-those areas lacking glandular differentiation-compared to well-differentiated (WD) and moderately differentiated (MD) portions of tumors. Forty-two of 68 (62%) invasive tumors with WD or MD glands showed moderate or strong expression of HER-2/neu in WD/MD areas; only 6 of 32 (19%) invasive tumors with PD areas showed similar expression in PD. In mutually exclusive patient sets, we also found a statistically different prevalence of HER-2/neu expression in patients with PD (6/32 cases; 19%) and without PD (29/47 cases; 62%) tumors (p < 0.001). Twenty-three cases had directly comparable areas of PD versus MD or WD. In 19 of 23 cases HER-2/neu expression was graded comparatively lower (or negative) in areas of PD than in MD or WD. Overall 46 of 79 cases (58%) showed moderate to strong HER-2/neu expression inclusive of all histologic grades, and 63 of 79 (80%) cases were HER-2/neu positive, if including weak or focal staining. There was no significant difference in the survival of patients with HER-2/neu-positive versus-negative tumors or in patients with versus without PD tumors. We have confirmed that although HER-2/neu gene expression is common to many pancreatic carcinomas, it is not common to tumors lacking glandular differentiation. HER-2/neu gene expression could not be related to survival differences--perhaps due to overall poor survival within adenocarcinomas of the pancreas--but the pattern of HER-2/neu expression suggests a relationship to glandular differentiation and early oncogenesis.

Adenocarcinoma↗
PubMed1997

Craniofacial zygomycosis caused by Apophysomyces elegans.

A fatal case of craniofacial zygomycosis caused by Apophysomyces elegans in a 52-year-old man was diagnosed by the presence of broad aseptate, branched hyaline hyphae in tissue from paranasal sinuses and surrounding areas, and isolation of the fungus from the same tissue. The patient suffered from idiopathic myelofibrosis as underlying disease, he was thrombocytopenic and was mildly hyperglycaemic. The infection represents the second case of craniofacial zygomycosis due to A. elegans.

Blood Vessels↗
PubMed1997

Regulation of bFGF expression and ANG II secretion in cardiac myocytes and microvascular endothelial cells.

Basic fibroblast growth factor (bFGF; fibroblast growth factor-2) and angiotensin II (ANG II), among other peptide signaling autacoids (cytokines), are known to regulate the phenotypic adaptation of cardiac muscle to physiological stress. The cell type(s) in cardiac muscle responsible for ANG II synthesis and secretion and the role of endogenous cytokines in the regulation of bFGF induction remain unclear. With the use of confluent, serum-starved, low-passage cultures of cardiac microvascular endothelial cells (CMEC), ANG II could be detected in cellular lysates and in medium conditioned by these cells with the use of high-performance liquid chromatography followed by radioimmunoassay. The secretion of angiotensins by individual CMEC could be detected with a cell-blot assay technique. ANG II secretion was decreased by brefeldin A, an agent that interrupts constitutive and regulated secretory pathways for peptide autacoid/ hormone synthesis, suggesting de novo synthesis, activation, and secretion of angiotensins by CMEC. In primary isolates of adult rat ventricular myocytes (ARVM) and CMEC, ANG II, acting at ANG II type 1 receptors in both cell types, was found to increase bFGF mRNA levels measured by ribonuclease protection assay. Endothelin-1 (ET-1), which is known to be synthesized by CMEC, and bFGF itself, which has been detected in both ARVM and CMEC, increased bFGF transcript levels in both cell types. Interleukin-1beta (IL-1beta), which like ANG II and ET-1 is known to activate mitogen-activated protein kinases in both ARVM and CMEC, increased bFGF mRNA levels only in cardiac myocytes. Thus cytokines such as ANG II, ET-1, bFGF, and IL-1beta locally generated by cellular constituents of cardiac muscle, including CMEC, regulate bFGF mRNA levels in a cell type-specific manner.

Angiotensin II↗
PubMed1997

Improved survival of en bloc renal allografts from pediatric donors.

PURPOSE: We developed a technical and immunological protocol to increase survival of renal transplants from pediatric donors. MATERIALS AND METHODS: En bloc kidneys (22) were procured from donors weighing 2 to 14 kg. (1 to 60 months old) and transplanted into adult recipients. In group 1 (12 patients) sequential therapy was used for kidneys with more than 35 hours of cold storage and immediate triple therapy (cyclosporine, azathioprine and prednisone) was used for those with less than 35 hours of cold storage. In group 2 (10 patients) OKT3 induction therapy was used. Mean followup was 4.7 years. RESULTS: Mean blood pressure at 1 and 4 years was not significantly different between the groups. Mean serum creatinine was not significantly different between the groups at 1 year but it was significantly less in group 2 at 4 years (1.9 +/- 1.0 versus 1.2 +/- 0.24 mg./dl., p <0.05). At 1 year of followup the complication rate was 75% in 9 of 12 patients in group 1, including 4 infections or leaks (2 lost), 6 rejections (3 lost) and 3 cases of thrombosis or hemorrhage, and 20% (p <0.01) in group 2 (1 patient had the hemolytic uremic syndrome leading to graft loss). Graft survival was significantly greater in group 2 at all 4 years of followup (p = 0.05). CONCLUSIONS: The success of pediatric en bloc renal transplantation can be enhanced by induction therapy in healthy recipients.

Child, Preschool↗
PubMed1997

Western blot analysis of serological response in Helicobacter pylori in acid peptic diseases.

A prospective study was undertaken in 70 patients presenting with acid peptic disease with the objective of characterising the serological response to Helicobacter pylori and finding antigens specific for the serodiagnosis of H. pylori infection. H. pylori status was assessed by smear microscopy, rapid urease activity, culture and histopathology of endoscopic gastric antral biopsy specimens. Serological characterisation was carried out by using western blotting of various antigenic components of H. pylori and subsequent enzymatic detection of antibodies against them. Four reactive bands in the molecular weight range of 45-65 kDa were present in all subjects irrespective of H. pylori status. Four to six immunoreactive bands in the molecular weight range of 21-45 kDa were found only in patients with positive H. pylori status and histopathologically proven gastritis. These immunoreactive components may be valuable in specific immunodiagnosis of H. pylori infection.

Adolescent↗
PubMed1997

Endoscopic stenting of minor papilla for symptomatic pancreas divisum.

Pancreatitis is one of the presentations of pancreas divisum. Endoscopic treatment by dorsal pancreatic duct stenting relieves symptoms in a majority of patients. We report a patient with pancreas divisum and calcific chronic pancreatitis in whom successful drainage of the dorsal duct with a stent through the minor papilla relieved the pain.

Adult↗
PubMed1997

Primary gastrointestinal lymphoma--disease spectrum and management: a 15-year review from north India.

OBJECTIVE: To analyze retrospectively the disease spectrum and outcome of primary gastrointestinal lymphoma (PGIL) in a tertiary referral center in north India. MATERIAL: Seventy five patients presenting with PGIL between January 1971 and December 1985 were evaluated. RESULTS: The 49 males and 26 females were aged 3.5-69 years (mean 34) at presentation. Abdominal pain, weight loss and vomiting were cardinal symptoms at presentation; the stomach was the most common site of involvement. Histologically, a majority of patients were classified as having diffuse poorly-differentiated lymphocytic lymphoma (46.7%) and diffuse histiocytic type (30.7%). Twenty seven (36%) patients had stage I disease, 31 (40%) stage II, 11 (14.7%) stage III, and 6 (8%) stage IV. At laparotomy, primary resection and anastomosis was carried out in 66 patients, while only biopsies were taken in nine. Forty eight patients received adjuvant radiation with or without chemotherapy. The mean follow-up was 3.9 years (range 1-14). The 5-year actuarial survival was 34%, 25% and 16% for stages I, II, and higher-stage disease, respectively. The survival was significantly better (p < 0.01) for gastric location (44%) compared to other sites (24%). CONCLUSION: PGIL was more common in the 3rd and 4th decades of life, with the stomach being the predominant site of involvement. Survival was better among patients with stages I and II disease, and gastric location of lesion.

Adolescent↗