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Biomedical subjects

J Singh

Publications and source records attributed to J Singh.

At least 361 records · Page 20Linked to original sources
PubMed1995

In vitro and in vivo genotoxicity of hormonal drugs. VI. Fluoxymesterone.

Genotoxic evaluation of a commonly used synthetic steroidal androgen, fluoxymesterone, was undertaken using a combination of in vitro and in vivo assays. The clastogenic potential of fluoxymesterone was evident from the chromosome aberrations and sister chromatid exchanges induced by it in the cultured human lymphocytes and also from the increased frequencies of micronuclei and sister chromatid exchanges in bone marrow cells of mice. However, in Ames Salmonella assay both with and without S9 mix and in host-mediated assay using bacterial strains of S. typhimurium as indicator organism, fluoxymesterone did not cause any significant increase/decrease in His+ revertants.

Animals↗
PubMed1995

Success rate and complications of intraoperative 0.2 mg/ml mitomycin C in trabeculectomy surgery.

Adjunctive chemotherapy with Mitomycin C (MMC) has been used in an attempt to modulate the wound healing response in glaucoma filtration surgery. A consecutive series of 20 eyes from 18 patients undergoing trabeculectomy with MMC intraoperatively was studied. Sixteen cases were considered high risk regarding surgical success and 4 patients with low tension glaucoma (LTG) required lower intraocular pressure (IOP) to prevent further visual field loss. Surgical technique involved the use of a limbal-based conjunctival flap and MMC 0.2 mg/ml applied via a sponge (under the scleral flap) to both scleral and conjunctival surfaces for 5 minutes. The mean follow-up period was 12.7 months (range 3-24). There were 17 successful eyes. Of these, 14 are high pressure glaucoma eyes with a mean pre-operative IOP of 30.9 +/- 10.9 mmHg and a mean postoperative IOP of 15.3 +/- 5.2 mmHg (p = 0.001). The remainder of the successful cases include 4 patients with LTG with a mean preoperative IOP of 17.8 +/- 0.5 mmHg and a mean postoperative IOP of 6.8 +/- 0.7 mmHg (p = 0.001). Serious complications included chronic repeated bleb leaks (n = 2) and scleral necrosis (n = 2). There was one case of hypotonous maculopathy. These results are comparable with those of other studies. Despite a relatively low dose of MMC serious side-effects were encountered. Management of these complications is described, and how these effects may be prevented by altering scleral exposure to MMC. In addition a possible explanation for the serious side-effects of MMC-treated trabeculectomies is presented.

Adult↗
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

Case studies in occupational medicine for medical undergraduate training.

Medical undergraduate tutorials in occupational medicine were introduced in 1993 in Singapore. The tutorials discuss three case studies of patients likely to be encountered in primary health care practice--occupational dermatitis, tinnitus in a noise-exposed worker, and the finding of anaemia in a pre-employment examination. The cases are used to illustrate the importance of identification of occupational factors in the causation of disease; consideration of occupational factors in the management of disease; and measures for prevention of occupational and work-related diseases and promotion of health at work. Staff and student responses to the case studies have been positive. All five staff members involved in the teaching enjoyed the experience, and over 90% of the 105 students who participated in the tutorial felt that the material was well prepared, the time was well spent, and that the tutorials had thrown new light on and overcome difficulties encountered during the course.

Curriculum↗
PubMed1995

Epidemiology of cholera in Delhi--1992.

Cholera is endemic in Delhi and is a highly seasonal disease. Suspected cholera cases are referred to Infectious Diseases Hospital, Delhi. Rectal swabs from 2783 cases were bacteriologically examined during 1992, out of which 1075 were found to be positive for Vibrio cholerae O1 biotype El Tor. First isolation was made on 3 April and the last on 14 December. About 87 per cent isolations were made between May and September, which are summer and monsoon months in Delhi. Detailed epidemiological information was collected for about 198 cases of diarrhoea out of which 103 were confirmed cases of cholera. Half of these cases occurred in children below 10 years of age. The other major group affected was adult females, especially housewives. All the cholera cases occurred in those who were illiterate or educated up to primary level. Important risk factors were: contact with person having similar illness, storage of water in wide-mouthed containers, use of glass or mug to draw water from containers, absence of sanitary latrines and habit of washing hands with water alone after defecation, before cooking and eating food. About 30 percent cases had access to piped water supply which was found safe in Delhi during 1992. The findings suggest that the hygienic practices were more important than contaminated water sources for transmission of cholera in Delhi during the year 1992.

Adolescent↗
PubMed1995

Concurrent evaluation of immunization programme by Lot Quality Assurance Sampling.

The current EPI methodology for identifying immunization coverage is simple and easy to carry out under field conditions and gives a good idea about immunization coverage. However, it is not useful for local managers. It does not identify small health units with poor performance. Information on performance at the local level is vital to enhance overall immunization coverage. Estimation of coverage on a small area basis can be made by Lot Quality Assurance Sampling (LQAS). LQAS was used in nine sub-centres of district Saharanpur. The methodology was found to be feasible and identified seven sub-centres with poor current performance. Although LQAS may not be a good substitute for current EPI methodology to evaluate immunization coverage in a large administrative area, it is suggested that LQAS is a useful additional method for routine monitoring and evaluation of health programmes on a small area basis, especially as the overall coverage increases.

Communicable Disease Control↗
PubMed1995

Training, attitudes, and income profiles of pediatric emergency physicians: the results of a 1993 survey of the American Academy of Pediatrics Section on Pediatric Emergency Medicine.

In late 1993, 562 questionnaires were sent to members of the Emergency Medicine Section of the American Academy of Pediatrics; of the questionnaires sent, 65% (365) were returned. Data were collected on 280 full-time practicing pediatric emergency physicians (PEPs). Eighty-two percent of these full-time PEPs have been practicing pediatric emergency medicine for less than 10 years, and two thirds of them are males. The majority work in pediatric emergency departments, devoting 28.1 clinical hours per week to their specialty. Ninety-nine percent of these full-time PEPs are board certified in pediatrics, and 61.5% are board certified in pediatric emergency medicine, whereas less than one quarter are fellowship trained. Approximately two thirds of these physicians feel that board certification in pediatric emergency medicine is a prerequisite for practicing; only one quarter feel that a fellowship in pediatric emergency medicine is required at this time. Average annual gross income for full-time PEPs was $111,000 per year; 62.8% of these physicians make more than $100,000 per year. PEPs indicated that diversity of their clinical practice and the medical acuity of their patients were the most desirable aspects of pediatric emergency medicine, whereas scheduling and the shift work nature of the profession, along with lack of follow-up in hospital practice, were seen as the least desirable aspects of the subspecialty.

Adult↗
PubMed1995

Transcriptional activation of the Escherichia coli bgl operon: negative regulation by DNA structural elements near the promoter.

The bgl operon of Escherichia coli is transcriptionally inactive in wild-type cells. DNA insertion sequences (IS) constitute a major class of spontaneous mutations that activate the cryptic bgl promoter. In an attempt to study the molecular mechanism of activation mediated by insertion sequences, transcription of the bgl promoter was carried out in vitro. Stimulation of transcription is observed when a plasmid containing an insertionally activated bgl promoter is used as a template in the absence of proteins other than RNA polymerase. Deletions that remove sequences upstream of the bgl promoter, and insertion of a 1.2 kb DNA fragment encoding resistance to kanamycin, activate the promoter. Point mutations within a region of dyad symmetry upstream of the promoter, which has the potential to extrude into a cruciform structure under torsional stress, also lead to activation. Introduction of a sequence with dyad symmetry, upstream of an activated bgl promoter carrying a deletion of upstream sequences, results in a fourfold reduction in transcription. These results suggest that the cryptic nature of the bgl promoter is because of the presence of DNA structural elements near the promoter that negatively affect transcription.

Base Sequence↗
PubMed1995

The response of neurons and microglia to blast injury in the rat brain.

Rats subjected to a single non-penetrative blast were examined for possible neuronal damage and glial reaction by immunohistochemistry and electron microscopy. The most dramatic feature in rats killed between 1 and 14 days after the blast was the widespread response of microglial cells in various parts of the brain in which the cells were hypertrophied and their surface antigens, like complement type three receptors (CR3), were upregulated. The blast wave also induced the vigorous expression of major histocompatibility complex (MHC) class I and II (Ia) antigen. In rats killed 21 days after the blast, the elevated immunoreactivity of microglia had subsided and at 28 days both the microglial external morphology and immunoreactivity were comparable to those of normal animals. In rats killed 4-7 days after the blast, the neurons in the cerebral and cerebellar cortex appeared normal except for the occurrence of some 'darkened' dendrites. The incidence of 'darkened' dendrites was most common in rats killed at day 14 but they were absent at 21 and 28 days. Microglial cells were closely associated with some of the 'darkened' dendrites. Results in this study show that a non-penetrative blast in rats provokes a widespread microglial activation suggesting increased endocytosis and immunological responses. However, it remains uncertain whether such a drastic response was a direct activation of the cells by the blast wave or elicited indirectly by some chemical factors released from the damaged brain tissues.

Animals↗
PubMed1995

Renal toxicity after oral administration of lead acetate during pre- and post-implantation periods: effects on trace metal composition, metallo-enzymes and glutathione.

The present study was undertaken to compare the effects of 10-50 mg/kg b.wt. of Pb acetate after chronic treatment through oral gavage on: (a) the distribution of trace elements such as Fe, Cu, Zn, and Mn, (b) enzyme activity of delta-amino levulinic acid dehydratase (delta-ALAD) and alkaline phosphatase, and (c) glutathione (GSH) in kidney and (d) delta-ALAD in blood of pregnant and non-pregnant mice. Treatment with Pb acetate was given on every alternate day for 4 weeks prior to mating and for 3-4 weeks until pregnancy became apparent and confirmed by laporatomy. Lead administration reduced the rate of reproduction as assessed by number of living viable embryos. During normal pregnancy renal Cu, Fe and GSH tended to decline although non-significantly and continued to do so after lead administration. Mn was considerably and significantly elevated, whereas activity of delta-ALAD (non-activated) was quite low in pregnant mice. Following administration of Pb acetate, kidneys of pregnant and non-pregnant dams accumulated Pb in a dose-dependent manner, but as compared to non-pregnant mice, Pb increase in pregnant dams was significantly lower. Pb toxicity was associated with the loss of delta-ALAD in blood and kidney, but unlike the non-activated form of delta-ALAD, the dithiothreitol-activated form of delta-ALAD declined in a significant amount. The residual activity showed a high degree of negative correlation with endogenous Pb as well as with Zn/Pb ratio. Pb toxicity did not modify renal Fe, Cu, and Zn in the pregnant state, but reduced renal Fe during pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1995

Antituberculosis treatment-induced hepatotoxicity: role of predictive factors.

Antituberculosis drug-induced hepatotoxicity is quite common. However, factors predicting its development are still controversial. The objective of the present study was to evaluate the role of certain factors (age and sex of the patient, alcoholism, chronic liver disease, hepatitis B virus carrier status, acetylator status, nutritional status and antituberculosis treatment (ATT) regimen) in predicting the development of ATT-induced hepatitis. In a case-control study, 60 consecutive patients with evidence of ATT-induced hepatitis were studied to assess the possible association of the above-mentioned factors with ATT-induced hepatitis. Body mass index was found to be significantly lower in ATT-induced hepatitis patients (17.2 +/- 2.7) than in controls (19.5 +/- 3.3) (p < 0.05). Pyrazinamide was used in addition to isoniazid and rifampicin in a significantly higher percentage of patients in the ATT-induced hepatitis group (70%) as compared with those in the control group (42%). No significant differences were observed between the two groups with regard to the rest of the parameters.

Adolescent↗