Search PubMed⌕ Search

Biomedical subjects

A Singh

Publications and source records attributed to A Singh.

At least 253 records · Page 14Linked to original sources
PubMed1999

Synergistic effects in enzymic reactions.

It has been shown that when two enzymes showing similar actions act in close proximity of each other they influence each other synergistically. The phenomenon of synergism is, however, not observed if the two enzymes are of dissimilar action type. The condition of closest proximity has been simulated by conducting the enzymic reactions inside the reversed micelles. In the present study we have experimented with alpha-amylase and invertase both hydrolysing enzymes and also with peroxidase and invertase which do not show similar actions.

Glycoside Hydrolases↗
PubMed1999

Social basis of deviant sexual behaviour: a historical perspective.

Sexual perversions are often a product of civilized life. Most societies permit some degree of deviant sexual behaviour as a relief from stress of routine life. Criteria for labelling such behaviour have changed over a period of time. There have been instances of normalizing deviant sexual behaviour by formation of pressure groups by the deviants e.g. homosexual clubs, particularly in Western countries. Attitude of church on masturbation & homosexuality has fluctuated from forbidding these activities to accepting these as harmless acts. Extra marital sex, premarital sex, homosexuality, fellatio, masturbation have been reported from almost all societies. Swinging and mate-swapping is more prevalent in the West. Social factors associated with deviant sexual behaviour are discussed. Incest lobbies have come up in U. S. Prostitution has also been there in all societies since antiquity. Earlier, prostitutes enjoyed a relatively higher social status. Their degradation started with the dawn of Christianity. In 1960s there was sexual revolution in U. S. with emphasis on free sex. There is evidence of slowing down of sexual revolution with the advent of AIDS. Safe-sex and fidelity are now being emphasized.

History, 21st Century↗
PubMed1998

Antitumour activity of diallyl sulfide on polycyclic aromatic hydrocarbon-induced mouse skin carcinogenesis.

Diallyl sulfide (DAS), a major flavour component of garlic, is known to modulate xenobiotic metabolism and possess antitoxic, bactericidal, antineoplastic, hypolipidemic and hypocholesteromic effects. In the present study, the anticarcinogenic activity of DAS on a 7,12-dimethylbenzanthracene (DMBA)- or benzo[a]pyrene (B(a)P)-induced mouse skin model of carcinogenesis was evaluated. DAS was applied topically either 1 h prior to or 1 h after the administration of DMBA or B(a)P. A significant protection from neoplasia was observed in DAS- and DMBA/B(a)P-exposed animals when DAS was applied topically compared to the animals exposed only to DMBA/B(a)P. In the animals where DAS was applied 1 h prior to the application of DMBA, a lower magnitude of neoplasia was recorded in terms of the cumulative number of tumours and average number of tumours per mouse during the entire period of study (28 weeks) compared to the animals exposed to DAS 1 h later, while in B(a)P-exposed animals, the antitumorigenic potential of DAS was more evident in the mice treated with DAS 1 h after the B(a)P exposure compared to the animals treated with DAS 1 h prior to B(a)P. The antitumour activity of DAS was of a much higher magnitude in B(a)P-induced carcinogenesis in comparison to animals exposed to DMBA in terms of tumour incidence, cumulative number of tumours and average number of tumours per mouse. The results suggest that DAS has a protective effect in PAH-induced mouse skin carcinogenesis.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1998

Acute limb ischemia after transplantation in a patient with persistent sciatic artery.

BACKGROUND: Improved surgical techniques have contributed to a better outcome in kidney transplantation, and graft failure secondary to technical complications is unusual. METHODS: We describe a surgical complication secondary to a rare and unexpected vascular anomaly in a pediatric renal transplant that resulted in considerable morbidity. RESULTS: Our patient had a persistent sciatic artery as a dominant source of blood supply to the lower limb. Ligation of this vessel during anastomosis with the transplant kidney vasculature led to severe ischemic damage to the leg. CONCLUSION: This vascular malformation, if undetected, can lead to serious complications. We present a review of the literature regarding this malformation and its management with regard to renal transplantation.

Adolescent↗
PubMed1998

Flow regulation of 72-kD collagenase IV (MMP-2) after experimental arterial injury.

BACKGROUND: MMP-2 plays a key role in basement membrane degradation and in the migration of proliferating smooth muscle cells after vascular injury. Because low flow and shear stress have been related to the localization and progression of intimal hyperplasia, we hypothesized that flow conditions modulate in vivo MMP-2 transcription and activity in a model of injury-induced intimal thickening. METHODS AND RESULTS: The right common carotid artery (CCA) was balloon-injured in 21 New Zealand White male rabbits. Flow was thereafter preserved (normal flow, n=7), reduced by partial outflow occlusion (low flow, n=7), or increased by ligation of the left CCA (high flow, n=7). In 15 other animals (controls without injury), flow was reduced (n=5), increased (n=5), or preserved (n=5). Mean blood flow and pressure in the right CCA were measured before and after flow modulation (day 0) and before the rabbits were killed (day 7). Northern analysis, gelatin-gel zymography, and fluorometric assays were performed on day 7 to determine MMP-2 mRNA levels and activity in relation to flow and intimal thickening. Mean flow was reduced from 21+/-1 to 7+/-1 mL/min (P<0.05) by outflow occlusion and increased to 31+/-2 mL/min (P<0.05) by ligation of the contralateral CCA. Blood pressure was not different between the flow groups. Hemodynamic parameters were similar for days 0 and 7 after flow modulation. In the injured right CCA, there was a 186% increase in MMP-2 mRNA with normal flow (P<0.05), a 366% increase with low flow (P<0.005), and only a 38% increase with high flow (P>0.05) compared with the uninjured CCA with normal flow. In the uninjured CCA, MMP-2 mRNA levels were increased by only 39% and 26% in the low- and high-flow groups, respectively, compared with normal-flow controls. The zymographic signal and quantitative fluorescent activity of gelatinase were markedly increased in both injured and uninjured CCAs subjected to low flow. Intimal thickening was observed after 1 week only in CCA segments with low flow and injury. CONCLUSIONS: Hemodynamic forces such as low flow upregulate injury-induced MMP-2 mRNA and appear to be more important in regulating MMP-2 activity than injury alone. This may facilitate migration of the smooth muscle cells and subsequent development of intimal thickening.

Animals↗
PubMed1998

PCB congener 77-induced ultrastructural alterations in the rat liver: a quantitative study.

Liver alterations were estimated morphometrically in male and female Sprague-Dawley rats that were fed PCB congener 77 (3,3',4,4'-tetrachlorobiphenyl) in concentrations of 0.01, 0.1, 1, 10 ppm or corn oil in diets for 13 weeks. A dose-dependent increase in the volume of smooth endoplasmic reticulum (SER) and an elevation in the volume of mitochondria following administration of the highest congener concentration (10 ppm) were estimated in the female rats. Hepatocytes of the male rats contained a significantly greater baseline volume of both SER and mitochondria compared to that in the females. A statistically significant (P < 0.05) change in the volumes of either SER or mitochondria in the PCB-fed males was not revealed. The authors concluded that the increase in mitochondrial volume was probably a necessary cellular adaptation to meet the heightened energy demands required by the SER to detoxify the PCB. The use of morphometric rather than a descriptive methodology allowed for a better determination of the hepatic alterations induced by PCB 77.

Administration, Oral↗
PubMed1998

Momordica charantia (Bitter Gourd) peel, pulp, seed and whole fruit extract inhibits mouse skin papillomagenesis.

The present study was designed to elucidate the inhibitory potential of Momordica charantia (Bitter Gourd) peel, pulp, seed and whole fruit extract on mouse skin papillomagensis with the modulatory influence of biotransformation system enzymes. Topical application of Momordica whole fruit extract (100 microl/animal per day) during the peri-initiation stage (1 week before and 2 weeks after initiation) by 7,12-dimethylbenz[a]anthracene (DMBA) and/or during the tumor promotion stage reduced the (i) tumor burden to 4.26, 3.72 and 3.11 (positive control value: 5.42); (ii) cumulative number of papillomas to 81, 67 and 53 (positive control value: 103); and (iii) percent incidence of mice bearing papillomas to 100, 94 and 94, respectively (positive control value: 100). In a comparison of the anticarcinogenic efficacy of Momordica peel, pulp, seed and whole fruit extract (100 microl/animal per day), after topical treatment during the peri-initiation and during the tumor promotion stage, revealed the modulation of the (i) tumor burden (tumors/mouse) to 3.06, 3.61, 3.17 and 3.11; (ii) cumulative number of papillomas to 49, 65, 54 and 53; and (iii) percent incidence of mice bearing papillomas to 84, 100, 94 and 94, respectively. Significant elevation in the sulfhydryl (-SH) level was observed in the liver and skin tissues by the topical treatment of Momordica peel, pulp, seed and whole fruit extract. Elevation in the hepatic levels of cytosolic glutathione S-transferase (GST) and microsomal cytochrome b, was also observed by the topical treatment of Momordica peel, seed and whole fruit extract. The results suggest the maximum chemopreventive potential is in the Momordica peel. Equivocal efficacy is in the Momordica seed and whole fruit extract. Biotransformation system enzymes may be the cause of this reduced papillomagenesis.

Animals↗
PubMed1998

Postnatal efficacy of Momordica charantia peel, pulp, seed and whole fruit extract in the detoxication pathway of suckling neonates and lactating mice.

The present study evaluates the postnatal efficacy of Momordica charantia peel, pulp, seed and whole fruit extract via assessing the modulation in the biotransformation system enzymes of suckling neonates and lactating mice. The peel, seed or whole fruit extract of Momordica (100 microl/animal/day) independently induced a significant increase in the hepatic levels of glutathione S-transferase (GST) and acid soluble sulfhydryl (-SH) after 14 or 21 days treatment in lactating dams (P < 0.01) and translactationally exposed neonates (P < 0.05). However, the elevation (P < 0.05) in hepatic cytochrome b5 (Cyt. b5) and cytochrome P-450 (Cyt. P-450) levels was observed only in the lactating dams treated with the respective extracts of peel, seed or whole fruit of Momordica. In lactating dams and suckling neonates the modulated levels of biotransformation system enzymes suggest the potential for the translactational passage of active principle(s) and/or metabolites of Momordica.

Animals↗
PubMed1998

Postnatal effect of smokeless tobacco on phytic acid or the butylated hydroxyanisole-modulated hepatic detoxication system and antioxidant defense mechanism in suckling neonates and lactating mice.

The present study evaluates the potential of smokeless tobacco to translactationally modify the chemopreventive efficacy of phytic acid and butylated hydroxyanisole (BHA) via modulation of the hepatic xenobiotic detoxication system and antioxidant defense mechanism in the murine system. Phytic acid (1000 mg/kg b.w./day) by gavage while BHA (1% w/w) in diet induced a significant increase in the levels of glutathione-S-transferase (GST), acid soluble sulfhydryl (-SH), cytochrome b5 (Cyt. b5) and cytochrome P-450 (Cyt. P-450) in lactating dams and suckling pups. The hepatic levels of GST and -SH were significantly depressed whereas microsomal Cyt. b5, Cyt. P-450 and MDA levels were elevated in groups treated with smokeless tobacco (50 or 100 mg/kg b.w./day). The data reveals the inhibitory potential of smokeless tobacco on phytic acid-induced GST/GSH system efficiency besides the significant augmentation by smokeless tobacco on phytic acid or BHA-induced microsomal phase I enzymes. The direct or translactational modulation in the levels of xenobiotic detoxication system enzymes suggests the potential of smokeless tobacco to modify the chemopreventive efficacy of phytic acid or BHA.

Animals↗
PubMed1998

Case of tumor neovascularization demonstrated by cardiac catheterization.

A 46-year-old man presented to his physician with nonspecific abdominal complaints. CT of the abdomen was obtained to investigate his symptoms, which showed significant pericardial effusion. One week after drainage of the pericardial fluid, his symptoms recurred and a transesophageal echo showed a right atrial tumor. Cardiac catheterization demonstrated right coronary artery neovascularization. A nonresectable primary angiosarcoma was found following median sternotomy and biopsy.

Cardiac Catheterization↗
PubMed1998

Technical hexachlorocyclohexane use trends in China and their impact on the environment.

Trends in production of technical HCH (BHC: 1,2,3,4,5, 6-hexachlorocyclohexane) in China have been surveyed from 1952 to 1983, when the Chinese government banned the use of this pesticide. While the total 4.46 million metric tons produced during this period make China by far the biggest producer and user of technical HCH, Japan consumed the largest accumulated average amount of this insecticide over arable land (84 t/kha for Japan versus 44 t/kha for China). The relationship between technical HCH production/usage trends and their impact on the environment has been studied. The similarity between total HCH isomer concentrations in Chinese environmental compartments in the beginning of 1980s and those in Japanese in the beginning of 1970s indicates the linkage between the average accumulated usage of technical HCH and the magnitude of contamination in the environment by this organochlorine insecticide. According to data from a national monitoring program on food contamination by organochlorine pesticides, residues of total HCH in foodstuffs in China decreased by about five times in rice, 127 times in fish, 32 times in poultry eggs, and 32 times in meat between 1978 and 1992.

Agriculture↗
PubMed1998

The paucity of minimal change disease in adolescents with primary nephrotic syndrome.

Data are sparse regarding the histological lesions associated with the primary nephrotic syndrome in adolescents. To our knowledge there are only two published articles that have specifically addressed the histopathological lesions that typify idiopathic nephrotic syndrome in the adolescent population. We reviewed our experience from the last 14 years of children between the ages of 12 and 18 years who were referred to our center for the evaluation of the nephrotic syndrome. A total of 29 adolescents met the inclusion criteria for this review. All patients were biopsied prior to the initiation of treatment. The sex ratio consisted of 52% males and 48% females and the racial breakdown was largely African-American, with 83% black adolescents, 7% Hispanic, and 10% Caucasian patients. Minimal change nephrotic syndrome (MCNS), the predominant lesion of children at an early age, was noted in only 20% of patients. The majority of patients (55.2%) had focal segmental glomerulosclerosis (FSGS); 7% had IgM nephropathy and 3.5% had diffuse mesangial hypercellularity. Only 7% of biopsied adolescents had membranoproliferative glomerulonephritis. Our results indicate that the most common lesion in this predominantly African-American patient population is FSGS, with only a small number showing MCNS. Thus, in our experience derived from a racially mixed population, adolescents with the nephrotic syndrome are less likely to have MCNS than younger children.

Adolescent↗
PubMed1998

Synthetic graft placement in the treatment of fascial dehiscence with necrosis and infection.

OBJECTIVE: The objective of this study was to describe the use of synthetic grafts in repairing fascial dehiscence complicated by fascial necrosis and infection after obstetric and gynecologic operations. STUDY DESIGN: A retrospective review of the operating room records at Hutzel Hospital (Detroit, Mich) was performed to find all cases of fascial dehiscence repaired during a 6-year period between January 1, 1991, and December 31, 1996. Patients with partial or complete disruption of the fascia with evidence of fascial necrosis and infection were included in this study. Demographic information; the initial surgical procedure, including type of incision; suture material; use of synthetic graft and closure technique for repair of dehiscence; postoperative complications, microbiologic results; antibiotic therapy; subsequent operations; length of hospital stay; and late complications were recorded. RESULTS: During the study period 52 patients underwent repair of fascial dehiscence; 36 of these had concurrent fascial necrosis and infection, including 4 women with necrotizing fasciitis. Eighteen patients were from the obstetric service and 18 were from the benign or cancer gynecology service. Ninety-one bacterial isolates were recovered from the infected wounds. Extensive fascial resection precluded closure without tension in 18 cases and necessitated synthetic graft placement to prevent evisceration. Graft materials included polypropylene (11 cases) and polyglactin (7 cases). Late complications of graft placement included extrusion of the graft in 3 patients and incisional hernia in 1. CONCLUSIONS: Extensive fascial débridement with resection prevents primary closure of wound dehiscence. Synthetic grafts permit primary closure of large fascial defects and can be used with extensive débridement in the presence of infection.

Abdominal Muscles↗
PubMed1998

The platelet thrombin receptor and postoperative bleeding.

BACKGROUND: We hypothesized that small amounts of thrombin desensitize the platelet thrombin receptor during cardiopulmonary bypass (CPB), resulting in postoperative platelet dysfunction and bleeding. METHODS: Seventy-nine patients were entered into a study designed to measure changes in platelet thrombin receptor function during CPB and to correlate them to postoperative bleeding. In addition to measurements of clinical blood loss, platelet function tests of aggregation, activation, and cell-cell adhesion were used. The thrombin receptor agonist peptide (TRAP) was used to activate the platelets. Flow cytometry was used to measure various platelet surface markers and platelet-white cell interactions during CPB. RESULTS: Compared with preoperative values, both aggregometry and flow cytometry measured a significant reduction of TRAP-induced activation immediately and up to 24 hours after CPB. The response of other activating agents returned to normal by 24 hours. Postoperatively, 8 of 79 patients required excessive blood transfusion (> or = 10 units of blood products) and had significantly decreased TRAP-induced aggregation response. CONCLUSIONS: Our results show that (1) platelet activation, aggregation, and adhesion to leukocytes induced by TRAP are reduced after CPB, (2) decreased thrombin receptor responsiveness is associated with excessive postoperative blood loss, and (3) because the aggregation and activation responses are different for TRAP and thrombin, there may be a second thrombin receptor on platelets that is protected from damage during CPB. These results imply that prevention of the CPB-induced effects on the thrombin receptor will lessen postoperative morbidity associated with blood transfusion.

Blood Loss, Surgical↗
PubMed1998

Operative outcome and hospital cost.

INTRODUCTION: Because of concern about increasing health care costs, we undertook a study to find patient risk factors associated with increased hospital costs and to evaluate the relationship between increased cost and in-hospital mortality and serious morbidity. METHODS: More than 100 patient variables were screened in 1221 patients undergoing cardiac procedures. Simultaneously, patient hospital costs were computed from the cost-to-charge ratio. Univariate and multivariate statistics were used to explore the relationship between hospital cost and patient outcomes, including operative death, in-hospital morbidity, and length of stay. RESULTS: The greatest costs were for 31 patients who did not survive operation ($74,466, 95% confidence interval $27,102 to $198,025), greater than the costs for 120 patients who had serious, nonfatal morbidity ($60,335, 95% confidence interval $28,381 to $130,897, p = 0.02) and those for 1070 patients who survived operation without complication ($31,459, 95% confidence interval $21,944 to $49,849, p = 0.001). Breakdown of the components of hospital costs in fatalities and in cases with nonfatal complications revealed that the greatest contributions were in anesthesia and operating room costs. Significant (by stepwise linear regression analysis) independent risks for increased hospital cost were as follows (in order of decreasing importance): (1) preoperative congestive heart failure, (2) serum creatinine level greater than 2.5 mg/dl, (3) New York state predicted mortality risk, (4), type of operation (coronary artery bypass grafting, valve, valve plus coronary artery bypass grafting, or other), (5) preoperative hematocrit, (6) need for reoperative procedure, (7) operative priority, and (8) sex. These risks were different than those for in-hospitality death or increased length of stay. Hospital cost correlated with length of stay (r = 0.63, p < 0.001), but there were many outliers at the high end of the hospital cost spectrum. CONCLUSIONS: We conclude that operative death is the most costly outcome; length of stay is an unreliable indicator of hospital cost, especially at the high end of the cost spectrum; risks of increased hospital cost are different than those for perioperative mortality or increased length of stay; and ventricular dysfunction in elderly patients undergoing urgent operations for other than coronary disease is associated with increased cost. Certain patient factors, such as preoperative anemia and congestive heart failure, are amenable to preoperative intervention to reduce costs, and a high-risk patient profile can serve as a target for cost-reduction strategies.

Cardiac Surgical Procedures↗
PubMed1998

Burn mortality in Chandigarh zone: 25 years autopsy experience from a tertiary care hospital of India.

An analysis of autopsy records of burn victims revealed that most burn deaths occurred in the age group 21-40 years (67 per cent) with female preponderance (61 per cent) in all age groups except in the extreme age groups. 62 per cent of burn cases originated in urban areas. The majority of subjects (99 per cent females and 76 per cent males) died as a result of flame burns. Kerosene was the most common factor (76 per cent) in burn deaths. 11 per cent of deaths were due to the stove bursting and 27 per cent of victims died due to leakage of oil from the stove. 39 per cent of subjects sustained burns when their clothes caught fire. Scalds (3.3 per cent), electrical (4.7 per cent) and chemical (2.3 per cent) burns were more commonly seen in males, mainly sustained at their working place. Accidental burns were observed in 80 per cent of subjects followed by suicidal (16.2 per cent) and homicidal burn assaults (4.1 per cent). Peak incidence of burns in females was observed between 5.01 a.m. and 11 a.m. (38 per cent), which was the time of least incidence in males (10.3 per cent). The opposite trend was seen between 11.01 p.m. and 5 a.m. Among males, burn deaths were more common (85 per cent) in those who were living alone, away from their families; whereas in women the incidence of burn deaths was higher (74 per cent) in those living with their families. The majority of deaths due to burns occurred within one week (77 per cent) of the incident. Septicaemia was the major cause of death (55 per cent).

Accidents↗