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Biomedical subjects

M V Shah

Publications and source records attributed to M V Shah.

At least 37 records · Page 2Linked to original sources
PubMed1992

Intracerebral hemorrhage due to cerebral arteriovenous malformations.

The most common presentation of a pial arteriovenous malformation (AVM) is spontaneous intracerebral hemorrhage (ICH). The peak incidence of ICH is early in the third decade of life. This article discusses the management of ICH of unknown etiology, ICH from angiographically visible AVM, and ICH from angiographically occult vascular malformations based on the current understanding of the natural history of these disease entities.

Cerebral Angiography↗
PubMed1991

Protamine--the need to determine the dose. Comparison of a simple protamine titration method with an empirical dose regimen for reversal of heparinisation following cardiopulmonary bypass.

A simple method of protamine titration using the Hemochron system was compared with an empirical dose protocol for reversal of heparinisation following cardiopulmonary bypass in 40 patients undergoing elective myocardial revascularisation. Protamine titration revealed a wide range for protamine requirement and resulted in a significant reduction in protamine dose compared with the empirical dose protocol (p less than 0.01). Heparin reversal was assessed as adequate in all patients. The titration technique was easy and straightforward to use in the operating theatre.

Cardiopulmonary Bypass↗
PubMed1991

Effect of induction-delivery and uterine-delivery on apgar scoring of the newborn.

Very short or prolonged induction-delivery interval (i.e. less than 5 minutes or more than 15 minutes) and uterine-delivery interval of more than 90 seconds has a definite effect on the apgar scoring of a newborn especially when general anaesthesia is administered as compared to regional anaesthesia for caesarean section.

Anesthesia, General↗
PubMed1990

Viral hepatitis.

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Hepatitis, Viral, Human↗
PubMed1989

The application of bovine brain microvessel endothelial-cell monolayers grown onto polycarbonate membranes in vitro to estimate the potential permeability of solutes through the blood-brain barrier.

Previously our laboratory (Rim et al., Int. J. Pharm. 32:79-84. 1986) described an in vitro blood-brain barrier (BBB) model consisting of cultured bovine brain microvessel endothelial cells (BMECs) grown onto regenerated cellulose acetate membranes. However, the utility of this in vitro BBB model system was limited because the regenerated cellulose acetate membrane and not the monolayer of bovine BMECs was rate limiting for the permeability of very lipophilic compounds. Therefore, in this study we have evaluated polycarbonate membranes as supports for growing bovine BMECs and for conducting in vitro drug permeability studies. Bovine BMECs were cultured on collagen-coated polycarbonate membranes (13-mm diameter, 12-microns pore size) which were then mounted into side-by-side diffusion cells for transport studies. The permeabilities of a series of solutes of varying lipophilicity (progesterone, estrone, testosterone, haloperidol, propranolol, antipyrine, caffeine, urea, acyclovir, ganciclovir, ribavirin, and glycerol) were determined and an excellent correlation (r = 0.97) was established between the permeability coefficients of the solutes and their log partition coefficients (PC)/(MW)1/2. These results suggest that bovine BMECs cultured onto polycarbonate membranes can be used as an in vitro model system for estimating the potential permeability of a solute through the BBB in vivo.

Animals↗
PubMed1988

Identification of a putative structural gene for cathepsin D in Caenorhabditis elegans.

Mutants of Caenorhabditis elegans having about 10% of wild-type activity of the aspartyl protease cathepsin D have been isolated by screening. Mutant homozygotes have normal growth rates and no obvious morphological or developmental abnormalities. The mutant gene (cad-1) has been mapped to the right extremity of linkage group II. Heterozygous animals (cad-1/+) show intermediate enzyme levels and animals heterozygous for chromosomal deficiencies of the right extremity of linkage group II have 50% of wild-type activity. Cathepsin D purified from a mutant strain has a lower activity per unit mass of pure enzyme. These data suggest that cad-1 is a structural gene for cathepsin D.

Animals↗
PubMed1987

Physicochemical determinants of drug diffusion across the conjunctiva, sclera, and cornea.

This investigation examined some of the barrier properties of the conjunctival, scleral, and corneal membranes. The diffusion of nadolol, timolol, propranolol, penbutolol, sucrose, and inulin was measured across the isolated corneal and scleral membranes of the rabbit using a two-chamber glass diffusion cell. Drug absorption across the cornea and the conjunctiva was studied in vivo by measuring precorneal drug clearance. The drug samples were analyzed either by HPLC or liquid scintillation counting (LSC). For all the compounds tested, the scleral permeability was significantly higher than the respective corneal permeability. The permeability coefficients of the beta-blockers varied in the following manner: propranolol > penbutolol > timolol > nadolol for the cornea, and penbutolol > propranolol > timolol > nadolol for the sclera. The cornea offered substantially more resistance to inulin, a polar, macromolecular substance, than did the conjunctiva. However, the cornea and conjunctiva offered comparable resistance to the smaller and less polar drug timolol. This information may serve as a basis for optimizing the intraocular delivery of drugs that are poorly absorbed across the cornea due to their physicochemical properties.

Animals↗
PubMed1987

Memory of cardiac anaesthesia. Psychological sequelae in cardiac patients of intra-operative suggestion and operating room conversation.

Thirty patients scheduled for elective cardiopulmonary bypass surgery were interviewed pre-operatively and postoperatively to assess changes in their emotional state and recollections, both aware and unaware, of intra-operative events. A random selection of patients heard a prerecorded audio tape towards the end of bypass after they were rewarmed to 37 degrees C. The tape contained suggestions for patients to touch their chin during the postoperative interview, to remember three sentences and to recover quickly. The interviewers were blind to the experimental condition. The experimental group touched their chins significantly more often than the control group (p = 0.015). Sentence recognition did not reach significance and this may be due to the small numbers and low salience of the stimuli. Seven patients (23%) recalled intraoperative events, five with the aid of hypnosis. Three reports (10%) were corroborated. Pre-operative medication (p less than 0.01) and postoperative anxiety (p less than 0.05) were significant predictors of those patients who reported recall.

Adult↗
PubMed1986

Intracuff and "leak-past" pressures of red rubber, latex and p.v.c. tracheal tubes. A laboratory and clinical study.

Measurements were made in the laboratory of the changes with time of the intracuff pressure, the leak-past pressure (the airway pressure at which gas begins to leak past the cuff) and the cuff volume for 9.5-mm tracheal tubes: red rubber, latex (both Leyland Medical) and p.v.c. (Portex Blue Line). The cuffs were inflated with air and exposed to air or air with enflurane or halothane, usually for 90 min. Measurements of leak-past pressure with these tubes were also made for 75 min in patients whose lungs were ventilated with air and enflurane or air and halothane. The following conclusions can be drawn. Enflurane and halothane had little effect. The intracuff pressure always decreased, but the cuff material crept under the continuous stress, so that cuff volume changed little. The leak-past pressure actually increased over at least 75 min with the p.v.c. tubes, but decreased consistently with the red rubber and latex tubes.

Adult↗
PubMed1986

Comparison between pressures measured from the proximal external jugular vein and a central vein.

Mean venous pressures were measured in 20 patients in whom a catheter, inserted via the external jugular vein, failed to pass centrally. The catheter used had a rounded end and two side holes. Pressures were measured with the patient's head in three different positions. The pressures were compared with the central venous pressures measured from a catheter inserted through an antecubital vein (and confirmed to be placed centrally). In all patients the differences between the mean pressures from the two sites were all within 3 mm Hg and were not influenced by alteration in head position or the side of jugular catheterization.

Central Venous Pressure↗
PubMed1986

"Patient demand" postoperative analgesia with buprenorphine. Comparison between sublingual and i.m. administration.

A randomized, double-blind, placebo-controlled study of buprenorphine was carried out in 20 patients after cholecystectomy. The drug was given on "patient demand" either i.m. (0.15 mg) or sublingually (0.2 mg) with a minimum dose interval of 30 min. Over the 24-h study period the mean demand by the sublingual route was 0.8 mg (range 0.6-1.2 mg) and by the i.m. route 0.66 mg (range 0.45-0.9 mg). Pain relief, by visual analogue scales and grading, was similar. Plasma buprenorphine concentrations varied more after sublingual administration. Either route was effective for the treatment of pain when administered by "patient demand".

Administration, Oral↗
PubMed1986

Mode of action of halothane on histamine-induced airway constriction in dogs with reactive airways.

To determine if clinical concentrations of halothane have direct relaxant effects on airway smooth muscle, the authors compared dose-response curves to histamine in the control state (thiopental) and during halothane anesthesia (1.0 and 1.5 MAC), in six basenji-greyhound (BG) dogs untreated and pretreated with atropine aerosols (10 mg X ml-1). Pulmonary resistance (RL) and dynamic compliance (Cdyn) were continuously monitored. Baseline airway tone was not significantly different during thiopental, halothane (1.0 MAC and 1.5 MAC), and after atropine aerosol administration. During thiopental anesthesia, histamine produced dose-related increases in RL and decreases in Cdyn. Both halothane and atropine significantly attenuated the bronchoconstriction induced by histamine 1 mg X ml-1. There was no significant differences in the extent of antagonism of histamine-related bronchoconstriction between halothane (1.0 MAC and 1.5 MAC) and the atropine aerosol. Moreover, in four dogs halothane anesthesia in the presence of atropine offered no additional protection compared with atropine alone. Because the protection afforded by halothane was not greater than that of atropine pretreatment alone, and the addition of halothane to atropine failed to increase the protection, it is concluded that block of vagal reflexes was the major action of halothane responsible for the attenuation of histamine-induced bronchoconstriction.

Aerosols↗
PubMed1986

The influence of nitrous oxide on oxyhaemoglobin dissociation and measurement of oxygen tension.

There are conflicting reports of the effect of nitrous oxide on the oxyhaemoglobin dissociation curve. We have therefore determined P50 of haemoglobin in the presence of either nitrous oxide or nitrogen and studied the upper portion of the curve in greater detail. No significant differences in the oxyhaemoglobin dissociation curve were observed when nitrous oxide was substituted for nitrogen. The oxygen tensions measured in gas mixtures were not significantly different when determined simultaneously with a polarographic oxygen electrode and the mass spectrometer when nitrous oxide was used instead of nitrogen.

Humans↗