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T Shah

Publications and source records attributed to T Shah.

64 records · Page 4Linked to original sources
PubMed1984

Kinetic properties of 5' nucleotidase in blood lymphocytes from healthy subjects, immunodeficient patients and cord blood.

The Km for AMP for 5' nucleotidase was increased in lymphocytes from patients with common variable (CVH) and sex linked (XLH) hypogammaglobulinaemia and from patients with chronic lymphatic leukaemia (CLL): the Vmax of the latter was low. The kinetic constants for cord blood lymphocytes are similar to adults and the Km does not change with age in lymphocytes from healthy adults. alpha-beta-Methylene adenosine diphosphate competitively inhibited 5' nucleotidase in lymphocytes from both healthy subjects and patients with CVH: the inhibitor constant (Ki) was higher for lymphocytes from patients with CVH than from control subjects. The concentration of zinc, an activator and modulator of 5' nucleotidase, was similar in control and CVH lymphocytes. It is concluded that lymphocyte 5' nucleotidase is functionally, abnormal in both primary hypogammaglobulinaemia and CLL and is deficient in the latter. These results provide support for the concept that CVH is a stem cell disease.

5'-Nucleotidase↗
PubMed1983

Enzyme analysis and subcellular fractionation of human peripheral blood lymphocytes with special reference to the localization of putative plasma membrane enzymes.

Human lymphocytes were isolated from defibrinated blood by Ficoll-Hypaque centrifugation with erythrocyte hypotonic lysis. Homogenates of mixed lymphocytes were subjected to analytical subcellular fractionation by sucrose gradient centrifugation in a Beaufay automatic zonal rotor. The principal organelles were characterized by their marker enzymes: cytosol (lactate dehydrogenase), plasma membrane (5'-nucleotidase), endoplasmic reticulum (neutral alpha-glucosidase), mitochondria (malate dehydrogenase), lysosomes (N-acetyl-beta-glucosaminidase), peroxisomes (catalase). gamma-Glutamyl transferase was exclusively localized to the plasma membrane. Leucine amino-peptidase, especially when assayed in the presence of Co2+, was also partially localized to the plasma membrane. Experiments with diazotized sulphanilic acid, a non-permeant enzyme inhibitor, showed that these plasma membrane enzymes are present on the cell surface. No detectable alkaline phosphatase was found in the lymphocytes. Acid phosphatase and beta-glucuronidase were localized to lysosomes and there was some evidence for lysosomal heterogeneity. Leucine amino peptidase, optimal at pH 8.0, showed a partial localization to intracellular vesicles, possibly lysosomes, especially when assayed in the presence of EDTA. These studies provide a technique for determining the intracellular distribution of hitherto unassigned lymphocyte constituents and serve as a basis for investigating the cell pathology of lymphocytic disorders.

Alkaline Phosphatase↗
PubMed1983

Lymphocyte enzyme activities in East African blacks: decrease in 5'nucleotidase and possible relation to immunosuppression.

Microanalysis of subcellular organelle marker enzymes was applied to cryopreserved lymphocytes (obtained and processed in the field) from East African blacks with moderate to severe malnutrition and subject to locally endemic parasitic and infectious diseases. An initial study demonstrated that activities of these enzymes, with the partial exception of catalase, were stable to cryopreservation. Cryopreserved and thawed lymphocyte specimens (1 to 3 X 10(6) viable cells) from 26 Africans and 20 Caucasian controls were studied. There was a highly significant decrease in 5'nucleotidase activity in these African subjects. Activity of another plasma membrane enzyme, gamma-glutamyl transferase, and of marker enzymes for other intracellular organelles, was not significantly different between the two groups, indicating that the nucleotidase alteration is highly specific. 5'Nucleotidase activity in a group of 17 East African blacks of high socio-economic status lay between the values obtained in the other two groups and was not significantly different from either. Further studies on 5'nucleotidase showed no evidence that the enzyme is functionally different in Africans. The differences in activity of this enzyme in Africans may reflect the known immuno-suppressive effects of infectious disease and malnutrition or may have a genetic basis which may in turn be associated with the pathogenesis of secondary immunodeficiency.

5'-Nucleotidase↗
PubMed1983

Lymphocyte enzyme activities in immunodeficiency syndromes with particular reference to common variable hypogammaglobulinaemia.

Circulating non-T lymphocytes had higher activities of 5'nucleotidase (plasma membrane), neutral alpha-glucosidase (endoplasmic reticulum) and basal leucine amino-peptidase than did T lymphocytes. Activities of catalase (peroxisomes), malate dehydrogenase (mitochondria), lactate dehydrogenase (cytosol) and N-acetyl-beta-glucosaminidase, beta-glucuronidase and acid phosphatase (lysosomes), were similar in the lymphocyte subfractions. Lymphocyte 5'nucleotidase (plasma membrane) in patients with common variable hypogammaglobulinaemia is much lower than normal. However, the decrease is less marked in X-linked hypogammaglobulinaemia, chronic lymphatic leukaemia or protein loosing enteropathy or in lymphocytes isolated from cord blood. Cells from patients with nephrotic syndrome had normal levels of 5'nucleotidase. Other plasma membrane marker enzymes (gamma-glutamyl transferase, leucine amino-peptidase) were normal in lymphocytes from patients with common variable hypogammaglobulinaemia. There is a selective reduction of mitochondrial (malate dehydrogenase) and cytosolic (lactate dehydrogenase) enzymes, with normal activities of lysosomal, peroxisomal and endoplasmic reticulum enzymes, in patients with common variable hypogammaglobulinaemia. The lymphocyte subcellular organelles in normal subjects and patients with common variable hypogammaglobulinaemia have similar properties on sucrose density gradient centrifugation. It is suggested that lymphocytes from patients with common variable hypogammaglobulinaemia show a specific enzymopathy and that this is not simply a reflection of cellular immaturity.

5'-Nucleotidase↗
PubMed1982

Studies on the kinetic properties and subcellular localization of adenine nucleotide phosphatases in peripheral blood lymphocytes from control subjects and patients with common variable primary hypogammaglobulinaemia.

Specific assays for 5'-nucleotidase, adenosine diphosphatase (ADPase) and Mg2+-dependent adenosine triphosphatase (Mg2+-ATPase) have been optimized for human lymphocytes and their subcellular localizations determined by sucrose density gradient centrifugation. 5'-Nucleotidase was localized solely to the plasma membrane of the lymphocyte. ADPase activity has been shown to have a dual localization to the plasma membrane and mitochondria, whilst Mg2+-ATPase was mainly located in the mitochondria. No [Na+,K+] activated Mg2+-dependent ATPase could be measured in these cells. We have confirmed the striking decrease in the specific activity of 5'-nucleotidase activity in lymphocytes from patients with common variable primary hypogammaglobulinaemia. In contrast, the specific activities of ADPase and Mg2+-ATPase showed no alteration in lymphocytes from the patient group when compared to controls. Thus the deficiency of ecto-5'-nucleotidase in the lymphocytes of patients with hypogammaglobulinaemia is a highly selective defect in purine metabolism.

5'-Nucleotidase↗
PubMed1982

Pulmonary functions during peritoneal dialysis.

Lung volumes, flows, flow volume loop, diffusing capacity and closing volume were studied in 7 patients (Group I) before, with 2 liter dialyzate in the peritoneal cavity and after 8 hours of peritoneal dialysis. The functional residual capacity, residual volume and the total lung capacity decreased (P less than 0.01, less than 0.05, and less than 0.05 respectively) with 2 liter dialyzate in the peritoneal cavity and returned to baseline after the dialyzate was removed. Arterial blood gas analysis was performed in another 8 patients (Group II) before, with 2 liter dialyzate in the peritoneal cavity, and after the dialyzate had been drained. No significant difference was observed in PaO2, PaCO2 or pHa during any phase of the study. It is concluded that except for a minor decrease in FRC, RV and TLC, there were no deleterious effects with the use of 2 liter dialyzate volume on gas exchange or pulmonary functions during peritoneal dialysis.

Adult↗
PubMed1981

Studies on the kinetic properties and subcellular localization of adenosine diphosphatase activity in human peripheral blood lymphocytes.

Using a recently developed radioassay, the conditions for measuring adenosine diphosphatase (ADPase) activity in human lymphocytes were optimized. Kinetic studies showed that the activity was optimal at pH 8.0 and required 0.2 mM MgCl2. The Km of the enzyme for ADP was 0.03 mM. Analytical subcellular fractionation showed that the ADPase activity was distributed between the plasma membrane and mitochondria. Studies with the non-penetrating inhibitor, diazotized sulphanilic acid, indicate that plasma membrane ADPase activity is located on the external aspect of the cell. Polymorphonuclear leucocytes were found to have about three times the ADPase activity. Lymphocytes, therefore, have the ability to generate AMP on their surface which can be further metabolized to adenosine by ecto-5' nucleotidase. A role for this system is discussed.

Apyrase↗
PubMed1978

Visualization of the intestinal tract by amniography in a fetus with esophageal atresia.

In pregnancies complicated by hydramnios, amniography can be used for the detection of fetal gastrointestinal obstruction. A case is presented in which the appearance of contrast material in the fetal gastrointestinal tract was noted in an infant who proved to have esophageal atresia and tracheoesophageal fistula. Presumably, the contrast reached the intestinal tract by aspiration and passage through the fistula.

Adult↗
PubMedDate not supplied

Low-dose amphotericin for prevention of serious fungal infection following liver transplantation.

AIMS: This study advances previously performed clinical studies of antifungal prophylaxis and prospectively evaluates the efficacy of low-dose amphotericin B preparations for the prevention of invasive fungal infection (IFI) in high-risk liver transplant (LT) recipients. METHODS: High-risk LT patients were recruited and randomised to openly receive intravenously either conventional amphotericin B (amB) at a dose of 15 mg daily, or liposomal amphotericin B (amBisome) 50 mg daily. Prophylaxis was continued until discharge from the intensive care unit (ICU), until patient death, or until time of conversion to high-dose amBisome for treatment of suspected or confirmed IFI. RESULTS: During the study period, 360 adult LTs were performed; 132 patients were eligible for 149 recruitment episodes into the trial, and 83 patients were recruited for 92 episodes. Of the 92, 48 patient episodes were randomised to receive amBisome prophylaxis, and 44 to receive amB. IFI was uncommon, diagnosed for 3 patients in the amBisome group, and for 2 in the amB group. Furthermore, Aspergillus was isolated on a single occasion during 92 episodes of prophylaxis. Fungal colonisation scores did not differ significantly between the 2 groups. There was a significant difference in the rates of survival to ICU discharge between the 2 groups (79.6% amBisome vs. 59.5% amB, P=0.038). Renal function measures including creatinine clearance at commencement and conclusion of prophylaxis, and at 12 months post transplant were not statistically different between the 2 groups. CONCLUSION: The use of amphotericin B, liposomal or non-liposomal preparations at low doses, for prophylaxis of IFI in high-risk LT patients, is associated with a low incidence of serious fungal infection. In this randomised study, low-dose amBisome prophylaxis was associated with an increased likelihood of successful discharge from the ICU.

Amphotericin B↗