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Biomedical subjects

S C Sharma

Publications and source records attributed to S C Sharma.

At least 145 records · Page 8Linked to original sources
PubMed1991

Enkephalin-immunoreactive cells in the mesencephalic tegmentum project to the optic tectum of the teleosts Salmo gairdneri and Salmo salar.

Immunocytochemistry using antibodies against Met-enkephalin and Leu-enkephalin has demonstrated a group of large enkephalin-immunoreactive neurons in the nucleus of the rostral mesencephalic tegmentum (mRMT) of two teleost fish. Salmo gairdneri and Salmo salar. Injections of cobalt-lysine in the medial optic tectum retrogradely labeled the above group of tegmental neurons. Tegmental neurons were labeled only ipsilaterally to the injection site. This indicates that enkephalinergic neurons in the nRMT project to the optic tectum, and that at least some of the enkephalinergic axons observed in the optic tectum belong to a tegmen-to-tectal pathway. Comparable enkephalinergic pathways have been described in reptiles and birds, where pretectal-mesencephalic nuclei contribute to the enkephalin-containing fibers that project to the optic tectum.

Animals↗
PubMed1991

Effect of piperine on bioavailability and pharmacokinetics of propranolol and theophylline in healthy volunteers.

The effect of piperine on the bioavailability and pharmacokinetics of propranolol and theophylline has been examined in a crossover study. Six subjects in each group received a single oral dose of propranolol 40 mg or theophylline (150 mg) alone or in combination with piperine 20 mg daily for 7 days. An earlier tmax and a higher Cmax and AUC were observed in the subjects who received piperine and propranolol. It produced a higher Cmax, longer elimination half-life and a higher AUC with theophylline. In clinical practice, the enhanced systemic availability of oral propranolol and theophylline could be exploited to achieve better therapeutic control and improved patient compliance.

Administration, Oral↗
PubMed1991

Radiation-induced proctosigmoiditis. Prospective, randomized, double-blind controlled trial of oral sulfasalazine plus rectal steroids versus rectal sucralfate.

In a prospective study, 37 consecutive patients with radiation-induced proctosigmoiditis were randomized to receive a four-week course of either 3.0 g oral sulfasalazine plus 20 mg twice daily rectal prednisolone enemas (group I, N = 18) or 2.0 g twice daily rectal sucralfate enemas plus oral placebo (group II, N = 19). The two groups were comparable with respect to demographic features, duration of symptoms, and clinical and endoscopic staging of the disease. Fifteen patients in group I and 17 in group II completed the trial. At four weeks, both groups showed significant clinical improvement (P less than 0.01 for group I and P less than 0.001 for group II) and endoscopic healing (P less than 0.01 for group I and P less than 0.001 for group II). When the two groups were compared, sucralfate enemas showed a significantly better response as assessed clinically (P less than 0.05), although endoscopically the response was not statistically different (P greater than 0.05). We conclude that both treatment regimens are effective in the management of radiation proctitis. Sucralfate enemas give a better clinical response, are tolerated better, and because of the lower cost should be the preferred mode of short-term treatment.

Administration, Oral↗
PubMed1991

Determination of estrogenic/antiestrogenic potential of antifertility substances using rat uterine peroxidase assay.

The effect of three compounds (clomiphene citrate, centchroman, embelin) and plant-derived methanolic extracts (Abutilon indicum and Butea monosperma) was studied on uterotropic and uterine peroxidase activities in ovariectomized rats. It was observed that these two parameters were highly correlated in response to treatment with these test materials and also to estradiol. It was suggested that the uterine peroxidase assay could be utilized as a biochemical parameter in the screening of new antifertility agents for their estrogenic/antiestrogenic properties.

Animals↗
PubMed1991

Retention of retinal axon collateral is responsible for induced ipsilateral retinotectal projections in adult goldfish.

In normal goldfish, optic axons innervate only the contralateral optic tectum. When one eye was enucleated and the optic nerve of the other eye crushed, the regenerating optic axons innervated both optic tecta. We studied the presence of bilaterally projecting retinal ganglion cells by double retrograde cell labeling methods using Nuclear Yellow and True Blue dyes. About 10% of the retinal ganglion cells were double labeled and these cells were found throughout the retina. In addition, HRP application to the ipsilateral tectum revealed retrogradely-labeled retinal ganglion cells of all morphological types. These results suggest that induced ipsilateral projections are formed by regenerating axon collaterals and that all cell types are involved in the generation of normal mirror image typography.

Animals↗
PubMed1991

Visual responses of morphologically identified tectal cells in the goldfish.

Intrinsic cells from the optic tectum of the goldfish were recorded intracellularly while undergoing photic stimulation, injected iontophoretically with horseradish peroxidase (HRP), and subsequently recovered in sectioned material. Unequivocal identifications were possible for 72 cells. The majority of these belonged to type I or type XIV, but types II, III, VI, IX and XIII were also observed. Type I cells exhibited a characteristic response to light flash with a strong initial hyperpolarization, and often had well defined receptive fields. Responses of type XIV vary, but often show very delayed responses, and spike potentials that do not affect the spike generating mechanism of the cell. Type XIII cells, which have bulbar axons, exhibit strong photic responses and long duration action potentials. Over 90% of cells recorded exhibited photic responses.

Animals↗
PubMed1991

The differential effects of cell density and NGF on the expression of tyrosine hydroxylase and dopamine beta-hydroxylase in PC12 cells.

Expression of neurotransmitter phenotype during development of the nervous system is determined by several micro-environmental factors including cell aggregation. In order to delineate the role of cell aggregation and nerve growth factor (NGF) in regulating catecholamine expression, tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DBH) mRNA levels were examined in PC12 cells at different cell densities with and without NGF treatment. Upon plating of PC12 cells from low density (0.3-1.0 x 10(5) cells/cm2) to high density (0.5-2.0 x 10(6) cells/cm2) TH mRNA levels increased 4-fold within 1 day and remained at this level for several days. In cells replated from high to low density, TH mRNA returned to original levels within 1 day. In addition to TH mRNA, TH protein and dopamine levels were also found to increase in high-density cultures. In contrast to the increase in TH mRNA, DBH mRNA decreased about 40% in cells plated from low to high density. Hence, cell density differentially regulated TH and DBH mRNA levels. Unlike cell density, NGF treatment led to a decrease in both TH and DBH mRNA levels. However, when NGF treated cells were replated from low to high density, TH and dopamine levels increased. Thus NGF did not alter the density dependent regulation of TH. Similarly, TH mRNA levels increased in F4 cells, a mutant PC12 cell line unresponsive to NGF, when plated from low to high density. DBH mRNA decreased to undetectable levels when NGF treated PC12 cells were plated to high density, demonstrating a synergetic effect of cell density and NGF treatment on DBH mRNA levels.

Animals↗
PubMed1991

A new design of Delclos dome cylinders using standard Cs-137 sources.

Surface dose rates around the currently-marketed Delclos uterine-vaginal afterloading dome (hemispherical) cylinders were calculated and measured for linear standard 3M cesium tube sources. Measurements were carried out using thin thermoluminescent lithium fluoride Chips on the surface of the cylinder and calculations at the same points were generated using a treatment planning computer. Wide surface dose variations were found for 2 to 3.5 cm diameter cylinders, but relatively small variation for 4 to 4.5 cm diameter cylinders. Attempting to achieve a uniform dose distribution around the entire dome surface of the cylinder, we have developed a new ellipsoidal design for the dome component that better conforms to the shape of the isodoses arising from the distal-most source. Thermoluminescent dosimetry indicates that the surface doses for the newly constructed cylinders are quite uniform, with variation within +/- 5%. The effect on surface dose is discussed when the ellipsoidal dome cylinder in combination with vaginal cylinders is used and multiple sources are laid end to end to treat the added areas of the vaginal wall.

Brachytherapy↗
PubMed1991

Electron beam effective source surface distances for a high energy linear accelerator.

The design of the Varian Clinac 1800 linear accelerator electron applicator system does not allow clearance for all head and neck patients to be treated at the standard calibration distance of 100 cm. Discrepancies have been found between dose calculations using the inverse square law for extended distances and their measured data. A 4 X 4 cm2 applicator at an energy of 9 MeV, for example, had dose differences of 13 and 23% at distances of 105 and 110 cm SSD. Because of these discrepancies, effective source surface distances (SSDeff) were determined for all the standard electron energies and applicators of a Clinac 1800. These effective source surface distances ranged from 41.6 cm to 92.6 cm for the 4 X 4 cm2 cone/6 MeV electron beam through the 25 X 25 cm2 cone/20 MeV electron beam. A summary of these distances and an analysis of the clinical use of both a best fit SSDeff and a common SSDeff for patient dosimetry calculations is presented.

Calibration↗
PubMed1991

Border separation for adjacent orthogonal fields.

Field border separations for adjacent orthogonal fields can be calculated geometrically, given the validity of some important assumptions such as beam alignment and field uniformity. Thermoluminescent dosimetry (TLD) measurements were used to investigate dose uniformity across field junctions as a function of field separation and, in particular, to review the CCSG recommendation for the treatment of medulloblastoma with separate head and spine fields.

Cerebellar Neoplasms↗
PubMed1991

Primary lymphoma of the bones of the foot: management of two cases.

Non-Hodgkin's lymphoma rarely presents with an osseous lesion in the foot. Two cases of primary lymphoma of the foot are reported. The patients presented with a history of pain and swelling of the foot. Radiographs revealed a lytic lesion in the calcaneus of one patient, and in the second metatarsal of the other. Open biopsy revealed high grade lymphoblastic non-Hodgkin's lymphoma of the diffuse variety. The patients were treated with localized radiation therapy and have been disease free for more than a year.

Adult↗
PubMed1991

High dose rate intracavitary therapy in advanced carcinoma esophagus.

Nine patients with advanced squamous cell carcinoma of the middle third of the esophagus were treated by high dose rate intracavitary therapy. The dose delivered was 12 Gy in two sessions at 1 cm from the center of the source. All nine patients were alive after 9 months. Six months after treatment, 4 patients had strictures which were dilated. At the end of nine months, 6 patients had dysphagia, four of whom had strictures and two had recurrence which was treated by further intracavitary irradiation. Intracavitary radiation using high dose rate, remote controlled afterloader has a significant role in palliation in patients with advanced esophageal carcinoma and avoids intubation.

Brachytherapy↗
PubMed1991

Spontaneous gastrointestinal perforation in the neonate.

Twenty seven cases of spontaneous gastro-intestinal perforation were treated from 1981 to 1990. Four perforations were in the stomach, 17 in the small bowel and seven in the large bowel. One of them had dual perforation, one in the stomach and another in the duodenum. The exact etiology remained obscure. Various factors observed were maternal obstetric complications, prematurity and perinatal asphyxia. Stress should be laid on early diagnosis by following up 'at risk neonates' thus, giving a better overall survival rate.

Female↗
PubMed1991

Topical corticosteroids usage in dermatology.

Prescribing of topical corticosteroids was studied in 200 patients attending the dermatology outpatients, randomly auditing the written prescriptions. Data with regard to potency, quantity, frequency, duration and site of application was collected and analyzed. Potent topical steroids were commonly used in 86 (43%) patients. The quantity of topical steroid was mentioned in only 4% patients whereas the frequency was specified in 77%, the site in 69% and the duration in 55% patients, respectively. The importance of these parameters is discussed, guidelines regarding use of topical steroids suggested.

Administration, Topical↗
PubMed1990

Afferent connections of the optic tectum in channel catfish Ictalurus punctatus.

Horseradish peroxidase was injected unilaterally into the optic tectum of the channel catfish, Ictalurus punctatus. The sources of tectal afferents were thereby revealed by retrogradely labeled neurons in various brain centers. Retrogradely labeled cells were seen in both the ipsilateral and contralateral telencephalon. The superficial pretectal area was labeled on both sides of the brain. Ipsilateral projections were also observed coming from the entopeduncular nucleus. Both the anterior thalamic nucleus and the ventro-medial thalamic nucleus projected to the ipsilateral optic tectum. Cells in the ipsilateral nucleus of the posterior commissure were seen to project to the tectum. Labeled fibers were visualized in the lateral geniculate nucleus ipsilateral to the injected tectum, however, no labeled cell bodies were observed. Therefore, tectal cells project to the lateral geniculate nucleus, but this projection is not reciprocal. No labeled cells were found in the cerebellum. Labeled cells occurred in both the ipsilateral and contralateral medial reticular formation; they were also observed in the ipsilateral nucleus isthmi. A projection was seen coming from the dorsal funicular nucleus. Furthermore, labeled cells were shown in the inferior raphe nucleus.

Afferent Pathways↗