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Biomedical subjects

S K Sharma

Publications and source records attributed to S K Sharma.

At least 307 records · Page 17Linked to original sources
PubMed1995

Effect of corticosteroid treatment on various serological & bronchoalveolar lavage abnormalities in patients with sarcoidosis.

Effect of daily oral prednisolone treatment was studied in 29 patients with pulmonary sarcoidosis. Twenty normal control subjects were also studied. Pretreatment absolute lymphocyte counts and proportion of lymphocytes in peripheral blood were significantly lower in patients with sarcoidosis as compared to normal controls. Total cell count and the proportion of lymphocytes in bronchoalveolar lavage (BAL) fluid were significantly higher in sarcoidosis. The proportion of CD3+ and CD4+ was significantly lower in peripheral blood and higher in BAL fluid in patients with sarcoidosis. Immunoglobulins (IgG, A and M) and complements (C3, C4 and CH50) were significantly higher both in peripheral blood and BAL fluid. Patients with sarcoidosis were treated with daily oral prednisolone (30 mg/day). Repeat studies were performed after an interval of 4-6 months in 20 patients with sarcoidosis. A significant increase in absolute lymphocyte counts in peripheral blood and decrease in the proportion of lymphocytes in BAL fluid occurred with prednisolone treatment. Proportion of CD3+, CD4+ and B cells increased in peripheral blood and decreased in BAL fluid. Complement and immunoglobulin levels revealed a significant reduction in peripheral blood and BAL fluid. It is concluded that patients with sarcoidosis have peripheral blood lymphopaenia and lymphocytic alveolitis. They have increased levels of complement and immunoglobulins both in the peripheral blood and BAL fluid. All these abnormalities show significant improvement with prednisolone treatment.

Adult↗
PubMed1995

Immunologic & pulmonary function abnormalities in tropical pulmonary eosinophilia.

Twenty six patients (24 males and 2 females) with tropical pulmonary eosinophilia (TPE) were studied. Arterial blood gas analysis, pulmonary functions, peripheral blood examination and bronchoalveolar lavage (BAL) were performed. Peripheral blood and BAL fluid analyses were performed in healthy volunteers. Pulmonary functions revealed a mild restrictive ventilatory defect with airways obstruction. Mild hypoxaemia was observed on arterial blood gas analysis. Serum immunoglobulins IgG (P < 0.01), IgA (P < 0.001) and IgM (P < 0.001) were significantly raised as compared to normal controls. Serum complement (C3) level was higher, however, it was not significantly different as compared to normal controls. Serum haemolytic component of the complement (CH50) was significantly higher (P < 0.001) in patients with TPE compared to normal control subjects. The immunoglobulins IgG, IgA and IgM in the BAL fluid were significantly (P < 0.001) increased as compared to normal controls. The fibronectin (FN) level was also significantly increased (P < 0.001) in the BAL fluid. It is concluded that patients with TPE have mild restrictive ventilatory defect with airways obstruction and mild hypoxaemia. They have eosinophilic alveolitis with increased levels of immunoglobulins in the peripheral blood and BAL fluid. The significance of elevated FN in the BAL fluid is not clear and serial estimations may have to be done in order to clarify its role in the pathogenesis of fibrosis in chronic TPE.

Adolescent↗
PubMed1995

Disposition kinetics and dosage regimen of cefotaxime in cross-bred male calves.

The disposition kinetics and dosage regimen of cefotaxime were investigated in cross-bred calves following a single intravenous administration of cefotaxime (10 mg/kg). The elimination rate constant and elimination half-life were 0.273 +/- 0.060 h-1 and 3.48 +/- 1.17 h, respectively. The apparent volume of distribution (Vd area) and total plasma clearance were 3.51 +/- 0.66 l/kg and 0.81 +/- 0.10 l.kg-1.h-1, respectively. To maintain a minimum therapeutic concentration of 0.6 microgram/ml, a satisfactory intravenous dosage regimen of cefotaxime in calves should be 11 mg/kg followed by 9 mg/kg at 6 h.

Animals↗
PubMed1995

Bronchoalveolar lavage in pulmonary tuberculosis: a decision analysis approach.

We assessed the utility of bronchoalveolar lavage (BAL) in the diagnosis of pulmonary tuberculosis (PTB) in 50 consecutive HIV-negative patients with clinical and radiographic findings suggestive of PTB, but with negative microscopy for acid-fast bacilli (AFB) on sputum smear. Patients were grouped, using a scoring system, into relative likelihoods of having PTB (I-IV, in descending probability). Patients were started on anti-tuberculosis treatment according to the BAL results. Bacteriological diagnosis of PTB was confirmed in 22/50 BAL; 11 (91.6%), seven (37%) and four (40%) of groups I-III, respectively. In 13 cases, an early diagnosis of PTB was made by positive microscopy for AFB on BAL; an alternative diagnosis was made in six cases (bacterial pneumonia 4, carcinoma 2). A decision analysis model was created to assess the overall utility of BAL. This suggested that in a region of high PTB prevalence, and when the clinical diagnosis of PTB is likely, empirical treatment is the best course of action, with BAL being reserved for further investigation of non-responders. Early BAL should be considered when the diagnosis of PTB is uncertain.

Adolescent↗
PubMed1995

Clinical profile, laboratory characteristics and outcome in miliary tuberculosis.

We report a retrospective series of 100 non-HIV adult patients with miliary tuberculosis (MTB) treated in a tertiary care centre. There were 51 males. Their mean age was 35 years. Predisposing conditions existed in 34. Twelve patients had larger-than-miliary (> 2 mm) shadows in their chest roentgenograms. Five presented with acute respiratory failure, and early treatment cured four of them. Hyponatraemia occurred in 42/60 patients (70%) for whom values were available. Twelve patients (12%) died of MTB. Temperature > or = 39.3 degrees C (p < 0.01), hypoalbuminaemia (p < 0.01), hyponatraemia (p < 0.001), history of vomiting (p < 0.001) and presence of crepitations on auscultation (p < 0.001) were independent predictors of mortality. Diagnosis of MTB is difficult even in an endemic area, as the clinical symptoms are non-specific and the chest roentgenograms do not always reveal classical miliary changes. A high index of clinical suspicion and diligent efforts in confirming the diagnosis are needed, as early therapy yields good results.

Adolescent↗
PubMed1995

Field studies on the mosquito repellent action of neem oil.

Repellent action of neem oil was evaluated against different mosquito species. 2% neem oil mixed in coconut oil provided 96-100% protection from anophelines, 85% from Aedes, 37.5% from Armigeres whereas it showed wide range of efficacy from 61-94% against Culex spp. Therefore, neem oil can be applied as a personal protection measure against mosquito bites.

Animals↗
PubMed1995

Vitamin B6 deficiency and galactose induced alterations in morphology and osmotic fragility of rat erythrocytes.

Recently, red blood cells have been investigated mainly for alterations in ion transporting capacity, membrane bound enzymes or modifications in the structure of its individual constituents in clinical and experimental urolithiasis. However, the implication of such modifications on the physical state or morphology of cells has not been investigated. Scanning electron microscopic studies performed in vitamin B6 deficient and/or galactose fed rat (established hyperoxaluric models) erythrocytes, showed the presence of large number of stomatocytes, spherocytes and other variously deformed cells as compared to discocytic cells seen in normal control group. These changes in shape were in concurrence with red cell osmotic fragility, which decreased both in vitamin B6 deficient and vitamin B6 deficient + galactose fed group (19 % and 33 % hemolysis at 4 g/l NaCl, respectively) while it increased in galactose control group (73 % hemolysis at 4 g/l NaCl) as compared to normal control group (55 % hemolysis at 4 g/l NaCl). These morphological and physical state alterations could be correlated with red blood cells' membrane cholesterol and phospholipid sub-class distribution. These findings suggest that some structural membrane changes occur due to vitamin B6 deficiency and/or galactose feeding, which may be responsible for the altered membrane functions known to be associated with pathogenesis of urolithiasis.

Animals↗
PubMed1995

Epidemiological observations on malaria in villages of Buhari PHC, Surat, Gujarat.

Investigations were carried out in the villages of Buhari PHC, Surat district, Gujarat to determine factors responsible for high prevalence of P. falciparum. The area is well-known for sugarcane cultivation, industrialization and frequent movement of labourers. The slide positivity rate (44.24%) and P. falciparum infections (95.37%) were significantly high. The children of 5-9 yrs of age group suffered maximum from malaria. The infection in children was found associated with splenomegaly also. High falciparum infection (82.35%) was found in labourers camping near villages out of which 90% afebrile cases were reported which were silent carriers and source of transmission. Chloroquine was effective in 75% cases despite of existence of resistant falciparum strain. Among seven anopheline species encountered, An. culicifacies was predominant and found breeding in most of the breeding sites. The status of the insecticide spray and its receptivity among the community were poor. The investigation led to the conclusion that adequate measures are required to deal with migratory labourers, improper insecticide coverage, poor surveillance and mass ignorance.

Adolescent↗
PubMed1994

Thrombin generation in human coronary arteries after percutaneous transluminal balloon angioplasty.

OBJECTIVES: The aim of this study was to investigate the relation between coronary atherosclerotic plaque injury and activation of the coagulation cascade. BACKGROUND: Thrombus formation after atherosclerotic plaque disruption has been implicated in the pathogenesis of atherosclerosis, unstable angina and myocardial infarction. METHODS: Biochemical markers of thrombin generation (prothrombin fragment F1+2) and thrombin activity (fibrinopeptide A) were measured in coronary blood before, during and immediately after percutaneous transluminal coronary angioplasty. After demonstrating that blood withdrawal through an angioplasty catheter does not artifactually elevate the plasma levels of these markers in patients after heparinization, coronary artery samples were collected proximal and distal to the lesion before and distal to the lesion after balloon inflation in 26 patients. RESULTS: Plasma levels of F1+2 measured proximal to the lesion before angioplasty (median 0.47 nmol/liter, 95% confidence interval [CI] 0.40 to 0.50) were significantly elevated after angioplasty (median 0.55 nmol/liter, 95% CI 0.46 to 0.72, p = 0.001). In contrast, plasma fibrinopeptide A levels measured proximal to the lesion before angioplasty (median 2.0 ng/ml, 95% CI 1.3 to 2.2) were similar to those measured after angioplasty (median 1.8 ng/ml, 95% CI 1.3 to 3.0, p = NS). After we defined a normal range of interassay variability on the basis of values obtained from samples drawn proximal and distal to the lesion before angioplasty, seven patients (27%) had a significant increase in F1+2 plasma levels. A significant increase in plasma fibrinopeptide A occurred in five of these seven patients. Lesions with dissection, filling defects or haziness on postangioplasty angiography were associated with more thrombin generation than lesions without these features. CONCLUSIONS: Markers of thrombin generation and activity can be collected safely and assayed accurately in heparinized blood withdrawn through an angioplasty catheter. Balloon dilation of coronary stenoses increases thrombin generation and activity within the coronary artery in a substantial subgroup of patients undergoing angioplasty.

Angioplasty, Balloon, Coronary↗
PubMed1994

An active recombinant p15 RNase H domain is functionally distinct from the RNase H domain associated with human immunodeficiency virus type 1 reverse transcriptase.

An active p15 RNase H domain, consisting of amino acids 427-560 of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) and a genetically engineered penta-histidine N-terminal affinity tag, was expressed in Escherichia coli and purified to apparent homogeneity by immobilized metal affinity chromatography. The purified p15 RNase H domain exhibited no substrate preference for [3H]poly(rG).poly(dC) compared to [3H]poly(rA).poly(dT), in contrast with the HIV-1 RT-associated RNase H, which showed a 30-fold preference for the former substrate. Unlike the HIV-1 RT-associated RNase H, when challenged with unlabeled substrate, the recombinant p15 RNase H domain was relatively nonprocessive in RNA degradative activity of the [3H]poly(rA).poly(dT) duplex. Kinetic studies using p15 RNase H showed substrate inhibition with an apparent K(i) value of 0.12 micron for the [3H]poly(rA).poly(dT) hybrid. Substrate inhibition was not observed for the HIV-1 RT-associated RNase H. The results show that the isolated p15 HIV-1 RNase H domain is functionally distinct from the recombinant HIV-1 RT-associated RNase H.

Amino Acid Sequence↗
PubMed1994

Human immunodeficiency virus type 1 (HIV-1) recombinant reverse transcriptase. Asymmetry in p66 subunits of the p66/p66 homodimer.

A recombinant p66 form of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) can be obtained [(1991) Biotechnol. Appl. Biochem. 14, 69-81] from crude Escherichia coli extracts by immobilized metal affinity chromatography (IMAC). We have analyzed the p66 HIV-1 RT, isolated in the presence of 0.3 M imidazole, by gel permeation HPLC on Superose 12. The results show that it contains two major distinct p66 forms (24.1 min and 28.3 min peaks) which are distinguishable from the purified homodimeric (p66/p66) HIV-1 RT (22.2 min peak). Protein peak 1 (24.1 min) is converted to a 22.3 min peak upon storage for 20 h at 4 degrees C. Under identical conditions, the isolated peak 2 (28.3 min) appeared as a conformationally heterogeneous mixture elaborated by peaks at 22.3 min and 25.9 min. The protein species thus obtained were active in the RNA-dependent DNA polymerase and RNase H activity assays and produced heterodimeric HIV-1 RT upon incubation with the HIV-1 protease. When the IMAC-purified, imidazole-free homodimeric (p66/p66) form of the enzyme was incubated with 0.3 M imidazole for 16 h at 4 degrees C, protein peaks at 28.3 min (peak A) and 30.5 min (peak B) were isolated by gel permeation HPLC. While both of these p66-containing species were stable and displayed identical RNA-dependent DNA polymerase activities, the protein in peak B was only 50% active in RNase H function compared with the protein from peak A. These imidazole-mediated dissociation studies support the hypothesis of partial unfolding of one of the RNase H domains of the p66/p66 homodimer, suggesting that the p66 subunits are asymmetric in the native enzyme.

Chromatography, High Pressure Liquid↗
PubMed1994

Galactosylated antibodies and antibody-enzyme conjugates in antibody-directed enzyme prodrug therapy.

Antibody directed enzyme prodrug therapy (ADEPT) has been studied as a two- and three-phase system in which an antibody to a tumor-associated antigen has been used to deliver an enzyme to tumor sites where it can convert a relatively nontoxic prodrug to a cytotoxic agent. In such a system, it is necessary to allow the enzyme activity to clear from the blood before prodrug injection to avoid toxicity caused by prodrug activation in plasma. To accelerate plasma clearance of enzyme activity, two approaches have been studied. The studies have been performed with a monoclonal anticarcinoembryonic-antigen antibody fragment A5B7-F(ab')2 conjugated to a bacterial enzyme, carboxypeptidase G2 (CPG2), in LS174T xenografted mice. In the first approach, a monoclonal antibody (SB43), directed at CPG2, was used, which inactivates CPG2 in vitro and in vivo. SB43 was galactosylated so that it had sufficient time to form a complex with plasma CPG2, resulting in the inactivation and clearance of the complex from plasma via the carbohydrate-specific receptors in the liver. Injection of SB43gal 19 hours after administration of the radiolabeled conjugate reduced the percentage of injected dose per gram in blood without affecting levels in the tumor. The second approach involved galactosylation of the conjugate so that it cleared rapidly from blood via the asialoglycoprotein receptors in the liver. Localization of the radiolabeled conjugate was achieved by blocking this receptor for about 8 hours with a single injection (8 mg/mouse) of an inhibitor that binds competitively to the receptor. This allowed tumor localization of the conjugate followed by a rapid clearance of the galactosylated conjugate from blood as the inhibitor was consumed. A tumor-to-blood ratio of 45:1 was obtained at 24 hours, which increased to 100:1 at 72 hours after the conjugate injection. These accelerated clearance mechanisms have been applied in antitumor studies in ADEPT.

Animals↗
PubMed1994

Anti-invasive activity of 3,7-dimethoxyflavone in vitro.

Invasion of MCF-7/6 human mammary carcinoma cells into embryonic chick heart fragments was studied in organ culture during 8 days. The effect of 31 polyphenolic compounds, belonging to the flavonoids, chalcones, or coumarins, was tested in this assay for invasion. The anti-invasive activity of 3,7-dimethoxyflavone was found at concentrations ranging from 1 to 100 microM. At these anti-invasive concentrations, no cytotoxic effects could be detected: the anti-invasive effect was reversible upon omission of the molecule from the medium, and treatment of MCF-7/6 cells or heart fragments did not affect subsequent outgrowth from explants on tissue culture plastic. The molecule did not inhibit growth of MCF-7/6 cell aggregates nor of heart fragments kept in suspension culture. The action mechanism of 3,7-dimethoxyflavone is the subject of our ongoing research.

Animals↗
PubMed1994

Effects of serotonergic agents on plasma prolactin levels in pyridoxine-deficient adult male rats.

Plasma concentration of prolactin was significantly reduced in pyridoxine-deficient as compared to control (pyridoxine-supplemented) adult male rats. Administration of pyridoxine to deficient rats resulted in a significant increase in plasma prolactin. The reduction in plasma prolactin in pyridoxine-deficient rats corresponded with the significantly reduced hypothalamic contents of pyridoxal phosphate and serotonin in pyridoxine-deficient rats. Plasma prolactin concentrations were also measured in response to serotonergic agents in both groups of rats. The administration of the 5HT1A agonist (8-hydroxy 2-n-dipropylamino tetralin) resulted in a significant increase in plasma prolactin and that of the specific 5HT1A antagonist spiroxatrine had the opposite effect. The results suggest that the hypothalamic serotonergic regulation of prolactin release is impaired in pyridoxine deficiency.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1994

Pharmacokinetics and dosage regimen of cefotaxime in cross-bred calves following single intramuscular administration.

The pharmacokinetics, penetration into erythrocytes and plasma protein binding of cefotaxime were investigated in cross-bred calves. Following a single intramuscular dose of cefotaxime (10 mg/kg), the absorption half-life and elimination half-life were 0.13 +/- 0.03 h and 2.97 +/- 0.72 h, respectively. The apparent volume of distribution and total body clearance were 3.28 +/- 0.72 L/kg and 0.78 +/- 0.08 L/kg per h, respectively. The extent of penetration into erythrocytes was 24-40% of the total blood concentration. Cefotaxime was bound to plasma proteins of calves to the extent of 25.5-33.6%. A satisfactory intramuscular dosage regimen for cefotaxime in calves would be 11 mg/kg followed by 10 mg/kg at 7 h intervals.

Animals↗
PubMed1994

Removal of endotoxin from antibody preparations for clinical use. Assessment of polymyxin-sepharose CNBr affinity chromatography.

Despite attempts to maintain asepsis, good manufacturing practices, and the use of terminal sterilization by millipore filtration, the nuclear practitioner is always worried about the possibility of endotoxin contamination. Methods, such as ion-exchange chromatography, have been tried for removing endotoxins during the preparation of radiolabeled antibodies, and so on. As suggested by Stevenson (1990), we evaluated the Issekutz technique (1) of endotoxin removal by affinity chromatography using a polymyxin cyanogen bromide (CNBr) Sepharose column. The endotoxin content of millipore filtrates of heat killed/sonicated suspensions of Pseudomonas pyocyaneus, E. coli were measured using a Sigma (St. Louis, MO) Endotoxin Assay Kit before and after filtration through such columns and compared with the results obtained using gel exclusion and ion-exchange columns of the same length and diameter. Reduction of endotoxin content to undetectable levels by the polymyxin column was observed. The use of such columns for terminal endotoxin removal analogous to terminal sterilization is advocated especially when developing a radiopharmaceutical such as radiolabeled antibodies for in house use.

Antibodies, Monoclonal↗
PubMed1994

Analysis of antibody-enzyme conjugate clearance by investigation of prodrug and active drug in an ADEPT clinical study.

Antibody-directed enzyme prodrug therapy (ADEPT) separates the cytotoxic function from the targeting function (5). An antibody-carboxypeptidase G2 (CPG2) enzyme is delivered prior to the nontoxic prodrug, CMDA, which is converted to a cytotoxic drug by the action of the localized conjugate at the tumor site. An indirect in vitro assay was developed to detect the presence of functional CPG2 in the plasma of patients in an ADEPT clinical trial. Compounds in the plasma of patients were characterized using liquid chromatography-mass spectrometry. Plasma at three different time points (prior to treatment, post-antibody-enzyme conjugate, and post-galactosylated anti-enzyme antibody clearing agent) was added to the CMDA prodrug and analyzed. Conversion of the CMDA prodrug to its active drug indicates that CPG2-conjugate remains in the plasma. This technique will provide essential data for the timing of prodrug administration in ADEPT.

Antibodies, Monoclonal↗