Search PubMed⌕ Search

Biomedical subjects

S Shah

Publications and source records attributed to S Shah.

At least 397 records · Page 22Linked to original sources
PubMed1985

Metabolism of L-ascorbic acid in the prostate of normal and scorbutic guinea pigs.

Guinea pig prostate was found to actively participate in the biosynthesis and catabolism of ascorbic acid. The key ascorbic acid biosynthetic enzyme L-gulono-gamma-lactone oxidase and the other two lactonases were found to be present in guinea pig prostate. The activities of dehydroascorbatase and diketogulonate decarboxylase, the enzymes for ascorbic acid degradation, were also detected in guinea pig prostate. Male guinea pigs kept under scorbutic condition for 7, 14, 21 and 28 days, were examined for prostatic metabolism of ascorbic acid. A significant but gradual decrease in the concentration of L-ascorbic acid was observed in prostate, total blood and leukocytes with the progression of scorbutic condition. There was an appreciable decrease in the rate of lipid peroxidation under the scorbutic condition. In the tissue fraction of scorbutic guinea pigs, the activities of biosynthesizing enzymes, measured in vitro, under optimum conditions were found to be higher with no significant alterations in the catabolizing enzymes. The implications of these findings are discussed in this paper.

Animals↗
PubMed1985

Heparin-induced thrombocytopenia. What is its real frequency?

A prospective study of 104 patients was undertaken to determine the frequency of severe heparin-induced thrombocytopenia in patients receiving either bovine lung or porcine mucosal heparin. One of 54 patients randomized to receive bovine heparin and two of 50 patients randomized to receive porcine heparin developed heparin-induced thrombocytopenia (platelet count less than 100,000/microliters). Although three previous studies suggest a remarkably high frequency of bovine heparin-induced thrombocytopenia, or a high frequency compared to porcine heparin, our study supports other evidence that clinically important, severe heparin-induced thrombocytopenia (platelet count less than 100,000/microliters) occurs in 10 percent of patients or less receiving heparin, and that there is no significant difference of occurrence between bovine and porcine heparin.

Acute Disease↗
PubMed1985

Effect of castration on the metabolism of L-ascorbic acid in rat prostate.

An appreciable decrease in the contents of prostatic ascorbic acid and dehydroascorbic acid along with an increase in diketogulonic acid was seen in rats ten days after castration. Castration caused a decrease in the activities of such biosynthetic enzymes as L-gulono-gamma-lactone oxidase and D-glucuronolactone-delta-hydrolase with no significant alteration in the activity of L-gulono-gamma-lactone hydrolase in the rat prostate. The activity of dehydroascorbatase, one of the degrading enzymes was, however, found to be elevated in castration. The implication of these results has been discussed.

2,3-Diketogulonic Acid↗
PubMed1984

Mass and heat transfer in vial freeze-drying of pharmaceuticals: role of the vial.

Flow of water vapor is impeded by three barriers or resistances: resistance of the dried-product layer, resistance of the semistoppered vial, and resistance of the chamber. The relationship between heat flow and temperature difference may be described by a vial heat transfer coefficient which has contributions from three parallel mechanisms: (a) direct conduction from the shelf to the vial via points of direct contact between the vial and shelf, (b) conduction through the vapor between the vial bottom and the shelf, and (c) radiative heat transfer. This report describes experimental studies of the resistance of semistoppered vials, the resistance of the chamber, and vial heat transfer coefficients. Mass transfer through the semistoppered vial has significant contributions from both Knudsen- and viscous-flow mechanisms. Stopper and chamber resistances are of the same magnitude and are about a factor of 10 less than the dried product resistance. All three heat transfer mechanisms are significant, the relative contributions depending on both the chamber pressure and the type of vial. Vial heat transfer coefficients are sensitive to the geometry of the vial bottom, and even vials of nominally the same specifications may differ significantly in heat transfer characteristics. Vials from the same lot are relatively uniform in their heat transfer characteristics, the relative standard deviation of the vial heat transfer coefficient being only approximately 4%. The temperature distribution in the frozen product is adequately described by a constant temperature gradient in the vertical direction and the thermal conductivity of ice.

Chemical Phenomena↗
PubMed1984

Platelet dysfunction in acute megakaryoblastic leukemia.

Acute megakaryoblastic leukemia occurred in an adolescent. There was considerable bleeding despite only moderate thrombocytopenia, and both platelet structure and platelet function were abnormal. To our knowledge, platelet dysfunction has only once been documented in this acute leukemia, although in other leukemias with megakaryocytic predominance, notable bleeding has been observed in the absence of thrombocytopenia.

Adolescent↗
PubMed1983

Physical chemistry of freeze-drying: measurement of sublimation rates for frozen aqueous solutions by a microbalance technique.

The sublimation rate of frozen solutions was studied as a function of freezing rate, thickness of dried product (l), temperature, residual air pressure, and solute concentration. Data are presented for pure water, aqueous potassium chloride, aqueous povidone, and aqueous dobutamine hydrochloride-mannitol (System I). The resistance of the dried product to water vapor flow (Rp) was evaluated from the sublimation rate and the sample temperature. The primary experimental technique was based on freeze-drying a cylindrical microsample isothermally, with the sample suspended from one arm of a vacuum microbalance. Methodology to evaluate resistance data from vial freeze-drying experiments is also described. In separate experiments, samples in the form of a thin (15-microns) film were visually observed through a microscope during freeze-drying. Freeze-drying of most samples appeared to occur by water vapor escaping through open channels created by prior sublimation of ice. Contrary to the usual theoretical model, Rp is neither independent of temperature nor directly proportional to l. Rather, Rp decreases with increasing temperature and the l dependence is normally of the form Rp = (A0 + A1l)/(1 + A2l), where Ai (i = 0, 1, 2) are constants. In several cases, Rp is very large near l = 0, decreases sharply at l congruent to 0.1 cm, and obeys the above equation where l greater than 0.2 cm, a result suggesting an amorphous surface skin which cracks on desorption of water. The temperature dependence of Rp suggests that, as the sample temperature approaches the eutectic (or collapse) temperature, hydrodynamic surface flow of adsorbed water is an important flow mechanism.

Air Pressure↗
PubMed1983

Comparative study of immunoactivity and bioactivity of sodium insulin.

The bioactivity of equal doses (by radioimmunoassay) of regular insulin and sodium insulin were measured in six preconditioned female mongrel hound dogs by a previously described bioassay. The hypoglycemic nadir of blood glucose induced by intravenous injection of the drugs was compared with the nadirs induced by a known amount of the international standard insulin. The level of blood glucose was monitored-instantaneously and continuously using a nonthrombogenic continuous glucose-monitoring system. The hypoglycemic effect of subcutaneously injected sodium insulin was compared with the effect of subcutaneously injected regular insulin. The two drugs were injected at 1-2-week intervals to seven dogs. While the bioactivity of intravenously administered sodium insulin was equal to the bioactivity of intravenously administered regular insulin, the hypoglycemic effect of subcutaneously injected sodium insulin differed from the effect of subcutaneously injected regular insulin. The blood glucose nadir after subcutaneous injection of regular insulin occurred 101 +/- 21 min after the injection. The nadir after subcutaneous injection of sodium insulin occurred 163 +/- 33 min after the injection.

Animals↗
PubMed1983

Treatment of obstruction of the superior vena cava by combination chemotherapy with and without irradiation in small-cell carcinoma of the bronchus.

In a randomised prospective trial of chemotherapy with and without radiotherapy in small-cell carcinoma of the bronchus, 37 of 366 patients presented with obstruction of the superior vena cava at the time of diagnosis. In the study all patients received four cycles of combination chemotherapy over a period of 12 weeks and, provided there was not progressive disease, then received either radiotherapy to the mediastinum and primary tumour followed by eight further courses of chemotherapy or eight cycles of chemotherapy alone. Of the 37 patients presenting with superior vena caval obstruction, nine had relapsed and treatment was stopped during or after the initial four cycles of chemotherapy. Of the remainder, 15 patients received radiotherapy plus chemotherapy and 13 chemotherapy alone. After four cycles of chemotherapy (12 weeks) 21 of the 37 patients had initial complete relief of symptoms secondary to superior vena caval obstruction, 10 had substantial but partial relief, and six had no relief. Twelve patients developed recurrence of superior vena caval obstruction, of whom six had received radiotherapy and four chemotherapy alone; two relapsed in the initial 12 weeks of the study. The median survival of the patients with superior vena caval obstruction allocated at diagnosis to either treatment arm was identical. The survival of patients with obstruction was similar to that of other patients in the main study. Chemotherapy is an effective treatment for superior vena caval obstruction and there appears to be no additional advantage in giving radiotherapy after 12 weeks of cyclical chemotherapy.

Antineoplastic Agents↗
PubMed1982

Distinction between normal and leukemic bone marrow by water protons nuclear magnetic resonance relaxation times.

Pulsed nuclear magnetic resonance studies have been carried out on bone marrow of normal human subjects and patients with leukemia: chronic myeloid leukemia (CML) and acute myeloid leukemia (AML). It was observed that the proton spin-lattice relaxation time (T1) value was discriminatory in the normal and leukemic cases with a statistical significance of (p less than 0.01). Ouabain treatment of cells did not show any perceptible change of T1 value when compared with the nontreated cells, indicating that the concomitant cation effluxes do not affect spin-lattice relaxation time. The water contents of normal, leukemic, and ouabain treated cells were in the range 60%-80%. Higher Fe levels were encountered in the normal than the leukemic samples, while levels of Zn, Cu, Mn, Co, and Ni were elevated in the leukemic samples compared with the normals. Despite the T1 differences observed, the multiparameter studies do not uniquely pinpoint factors responsible for the elevation of T1 in the malignant state.

Bone Marrow↗
PubMed1982

Neuroendocrine carcinoma of the skin in a young adult.

Neuroendocrine (Merkel cell) carcinoma of the skin is usually a tumor found in elderly individuals. Microscopically, the tumor is a small cell carcinoma that involves primarily the dermis. The dominant ultrastructural features are the presence of short cell processes containing small, dense-core, membrane-bound granules. The tumor is often locally aggressive, has the potential to metastasize to lymph nodes, and eventually causes death. The authors report a case of such a neoplasm that affected a 24-year-old man with congenital ectodermal dysplasia. It was associated with a concurrent basal cell carcinoma.

Adenocarcinoma↗
PubMed1982

Splenic lymphangioma: luminal surface ultrastructure; a scanning electron microscopic study.

A splenic lymphangioma removed from the abdominal cavity during an exploratory laparotomy in a 16 year old girl was studied by light microscopy and scanning electron microscopy (SEM). The tumor was composed of numerous vascular channels some of which were filled with clotted lymph. SEM revealed these channels to be lined with an uniform endothelial lining composed of two morphologic cell types: one with a smooth surface; the other with numerous microvilli. The literature on the SEM of lymphatic vessels and lymphangiomas is reviewed and compared to the splenic lymphangioma.

Adolescent↗