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Biomedical subjects

N Shaikh

Publications and source records attributed to N Shaikh.

35 records · Page 2Linked to original sources
PubMed1990

Visual analogue scales distinguish between low urinary flow rates due to impaired detrusor contractility and those due to bladder outflow obstruction.

In patients with symptoms suggestive of bladder outflow obstruction and a free flow rate less than 12 ml/s a visual analogue scale was used to measure the response to the question "Compared to 5 years ago, how thick is your stream when you pass urine?". The visual analogue scale compared favourably with cystometry in distinguishing between low flow rates resulting from impaired detrusor contractility and low flow rates due to bladder outflow obstruction. A visual analogue scale may serve to alert the surgeon to the presence of impaired detrusor contractility and the need for a fuller urodynamic assessment in patients with a low urinary flow rate prior to consideration for prostatectomy.

Aged↗
PubMed1990

Mechanisms of perfused kidney cytoprotection by alanine and glycine.

We examined the cytoprotective action of individual amino acids in isolated perfused kidneys during perfusion with either 10 mM lactate or 5 mM glucose. In the absence of amino acids inulin clearance fell rapidly, whereas fractional excretion of phosphate, lactate, or glucose increased to more than 30%; lactate dehydrogenase was released into perfusate and alkaline phosphatase into the urine. Functional deterioration was less in kidneys from rats rendered chronically water diuretic by drinking 5% glucose. Adding 5 mM glycine, L-alanine, beta-alanine, or D-alanine to the perfusate also prevented functional deterioration and release of enzymes. Glycine perfusion increased total phospholipid per microgram DNA by 6%. Aspartate, glutamate, glutamine, taurine, isoleucine, leucine, and valine were not protective. Serine, proline, and alpha-aminoisobutyric acid had small protective effects. Micropuncture measurements of proximal tubular free- and stop-flow pressures showed no effect of L-alanine on glomerular hemodynamics. L-Alanine increased oxygen consumption by both glucose- and lactate-perfused kidneys and increased gluconeogenesis by lactate-perfused kidneys but did not alter renal ATP content or energy charge. L-Alanine was not consumed during 70 min of perfusion and its protective action was not inhibited by blocking transamination with 0.5 mM amino-oxyacetate. The protective action of glycine was not inhibited by blocking glycine metabolism with 0.1 mM cysteamine. Thus the beneficial effects of L-alanine and glycine do not require their metabolism. These observations suggest that small neutral amino acids prevent tubular disruption through their physicochemical effects, which can stabilize membrane protein tertiary structure.

Alanine↗
PubMed1989

Actions of medroxyprogesterone acetate on the efficacy of cytotoxic drugs: studies with human breast cancer cells in culture.

Human breast cancer cells (MCF-7) showed increased responses to methotrexate and vincristine after a 48-hr pre-treatment with medroxyprogesterone acetate. The effect of the hormone, which was detectable at concentrations of between 10 and 100 nM, was independent of its growth-inhibitory action. These findings confirm a previous clinical study and have important implications with regard to the management of advanced breast cancer.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1988

Effects of human breast fibroblasts on growth and 17 beta-estradiol dehydrogenase activity of MCF-7 cells in culture.

The effect of conditioned medium from human breast fibroblasts on growth and 17 beta-estradiol dehydrogenase (E2DH) activity of the MCF-7 human breast cancer cell line has been investigated. Fibroblasts were derived from normal and tumorous (benign and malignant) breast tissue. Conditioned medium from normal derived fibroblasts inhibited the growth of MCF-7 cells, the effect being statistically significant by day 3 of culture. In contrast, conditioned medium from benign and malignant derived fibroblasts significantly enhanced the growth of MCF-7 cells by day 9 of culture. When added to MCF-7 cells for three days, conditioned medium from all three types of fibroblasts increased E2DH activity in the reductive direction (estrone (E1)----estradiol (E2] 2-3 fold. There was little or no effect on the oxidative direction (E2----E1). After 12 days, enzyme activity in the reductive direction was still markedly increased, the effect being greatest in conditioned medium from fibroblasts derived from malignant breast tissue, and least in conditioned medium from fibroblasts derived from benign breast tumors. These results demonstrate that human breast fibroblasts may have paracrine influences on neighboring epithelial cells in vivo.

17-Hydroxysteroid Dehydrogenases↗
PubMed1988

Endocardial mapping of ventricular tachycardia in the intact human ventricle: evidence for reentrant mechanisms.

A balloon array of 112 electrodes was used to obtain simultaneous recordings of endocardial electrograms during intraoperative mapping studies of ventricular tachycardia. Introduction of the balloon through a left atriotomy and across the mitral valve allowed endocardial activation maps to be obtained in the intact left ventricle. Of 20 patients with coronary artery disease studied in this way, suggestive evidence of endocardial reentry was found in 6. Three separate reentrant mechanisms were observed. In two patients, a single broad wave front of continuous recirculating activation reminiscent of a vortex was initiated by the formation of a functional arc of block in response to premature stimuli. In five patients, premature stimuli again produced a functional arc of block, which was circumvented by two opposing wave fronts that united on the distal side. Retrograde penetration by a narrow isthmus of slow conduction through the block initiated the tachycardia, whose activation sequence was consistent with figure eight reentry. In one patient, premature stimuli produced a region of delayed potentials. Critical timing of these resulted in microreentry in an adjacent circumscribed site, which formed the site of origin of the ensuing tachycardia. The microreentrant signals were not detected by standard unipolar recordings, but were seen on simultaneously recorded high gain electrograms. In 14 patients, although mapping identified a site of origin, the activation patterns showed either radial spread or incomplete circles. Detection of reentrant mechanisms during intraoperative mapping required high density electrode arrays and refined high gain recordings. An intact ventricle may facilitate intraoperative initiation of tachycardia.

Electrocardiography↗
PubMed1988

Electrical ablation with a balloon electrode array: chronic electrophysiologic response.

An intraoperative endocardial array of electrodes which permits simultaneous recordings from multiple sites in the intact ventricle is currently in clinical use and has provided the opportunity for exploring electrical ablation as an alternative to standard surgical ablative techniques requiring a ventriculotomy. A variation of the electrical ablative procedure adapted for this intraoperative purpose was studied in seven dogs to determine its long-term electrophysiologic and structural effects on ventricular myocardium. With the dogs on cardiopulmonary bypass, a mesh-covered latex balloon was introduced into the left ventricle via an atriotomy. Five damped sinusoidal discharges (4 of 200 J per 2 electrodes, one of 100 J to the remaining electrode) were delivered to nine silver bead electrodes sutured at 1 cm intervals onto the mesh and arranged in a 2 x 2 cm2 array. At 5-8 weeks following the ablation, no ventricular arrhythmias could be induced in any of the dogs using standard stimulation techniques. The scar produced by the ablation consisted of dense fibrous tissue, and was well demarcated from surrounding normal myocardium. Cellular electrophysiology confirmed that no action potentials could be recorded within the scarred area while at distances of 1 mm from the scar border, normal responses could be elicited from both muscle cells and Purkinje fibers. The adaptation of the described electrical ablative procedure produces an electrophysiologically inert scar.

Action Potentials↗
PubMed1987

Activation sequence of ventricular tachycardia: endocardial and epicardial mapping studies in the human ventricle.

Thirty-five patients with ischemic heart disease and ventricular arrhythmias underwent intraoperative activation mapping at the time of coronary artery bypass surgery. During ventricular tachycardia, the sequence of activation in the intact ventricle was recorded simultaneously from 110 endocardial or 110 epicardial sites, or both. A balloon array of electrodes, inserted across the mitral valve, was used to obtain endocardial recordings in the left ventricle, and this appeared to facilitate the induction of ventricular tachycardia. Of 61 episodes of tachycardia, 16 (15 patients) were recorded with the epicardial sock and 45 (20 patients) with the additional use of the endocardial balloon. The sequence of activation during tachycardia was observed to conform to one of four configurations: monoregional spread was the most common activation sequence recorded on both the endocardium and epicardium, while biregional activation and figure eight sequences were recorded exclusively on the epicardium and endocardium, respectively. The fourth sequence was a circular spread of activation observed on both surfaces. Continuous activation throughout the tachycardia cycle length was an infrequent finding. Simultaneous recordings of endocardial and epicardial activation were obtained in 45% of episodes. The sequence of activation recorded on one surface was matched by a similar sequence on the remaining surface in less than half of these. The onset of endocardial activation preceded that of the epicardium in greater than 90% of tachycardia episodes, and the duration of left ventricular endocardial excitation often exceeded that recorded epicardially over both ventricles. The epicardium, however, did appear to be an important determinant of surface electrocardiographic configuration.

Cardiac Catheterization↗
PubMedDate not supplied

Growth inhibition of human breast cancer cells by herbs and phytoestrogens.

Epidemiologic studies have suggested that consumption of phytoestrogen-rich foods may protect against breast cancer, and phytoestrogens such as genistein have been reported to both inhibit and stimulate the growth of some human breast cancer cells. The phytoestrogens genistein, daidzein, biochanin A, and coumestrol were tested and found to inhibit serum-stimulated growth in both T-47D and MCF-7 breast cancer cells at 10-100 microM. Extracts of several estrogenic herbs, including hops, black cohosh and vitex, inhibited growth of T-47D cells. These in vitro results suggest that certain herbs and phytoestrogens may have potential in the prevention of breast cancer.

Anticarcinogenic Agents↗
PubMedDate not supplied

Comparative efficacy of three measles vaccines in Indian children.

A Comparative study of three types of measles vaccines was undertaken among 1005 children. Of these 527 were vaccinated with the Serum Institute of India (SII) vaccine, 230 with Schwarz (SC) and 248 were vaccinated with Edmonston-Zegreb (EZ) vaccine (imported from Zegreb). Though the majority of children reacted favourably with all the three vaccines (SII: 98.43%; SC: 93.40%; EZ: 93.0%) with a rise in titre, but the percentage of seroconversion was significantly higher with the SII vaccine (p < 0.01). The Schwarz and Edmonston Zagreb vaccines showed significantly less GM titre as compared with the other age group i.e. 9-12 months (p < 0.05). With Serum Institute of India (SII) vaccine the GM titres were almost similar in the different age groups. The overall GM titre obtained with the SII vaccine was significantly higher than the SC vaccine (p > 0.001) as well as the EZ vaccine (p > 0.001). It is of interest to note that among the infants, 22.5% children had measles antibody in them before vaccination.

Antibodies, Viral↗
PubMedDate not supplied

Quantitative analysis of epidermal growth factor in human benign prostatic hyperplasia and prostatic carcinoma and its prognostic significance.

The incidence of prostatic carcinoma (PC) is increasing worldwide. Despite the discovery by Huggins in 1941 of the hormone dependency of this tumour, the overall prognosis and survival for patients with advanced disease has not changed. The prognosis for individual patients with PC cannot be accurately predicted by factors such as clinical stage and histological differentiation of the tumour. There is therefore a need to investigate new prognosis factors to assess their role.

Aged↗