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Biomedical subjects

A Singh

Publications and source records attributed to A Singh.

At least 289 records · Page 16Linked to original sources
PubMed1998

Sensitization to different species of Aspergillus in bakery workers and general atopic population.

Six species of Aspergillus predominant in the bakery environment--Aspergillus flavus, A. fumigatus, A. nidulans, A. ochraceous, A. sydowi and A. versicolor--were studied for their role in causing Type 1 hypersensitivity among bakery workers and atopic patients from the general population (PGP). Antigenic extracts from the above species were prepared for in vivo and in vitro studies. The IEF, SDS-PAGE, skin test, ELISA and immunoblot techniques were performed to detect the biochemical- and clinico-immunological characteristics of these species. Among those tested, the important fungal sensitizers among the bakery workers and patients from the general population were A. sydowi, A. fumigatus, A. nidulans and A. ochraceous. The protein fractions of different species were in the acidic region (pI 3.0-6.5) and in the molecular weight range of 13.0-91.0 kDa. The protein fraction of 44.0 kDA of A. flavus and 20.0 and 70.0 kDa for A. fumigatus showed IgE binding in the sera of bakery workers only. Significantly, raised IgG antibodies to different species were recorded among the bakery workers as compared to the PGP group. The study showed that different species of Aspergillus are of potential allergenic significance in bakery workers and the general atopic population.

Allergens↗
PubMed1998

Antitumor activity of diallyl sulfide in two-stage mouse skin model of carcinogenesis.

It has been reported that diallyl sulfide (DAS), a sulfur-containing volatile compound in garlic (Allium sativum), exerts anticarcinogenic activity in various rodent tumor models. In the present study, the antitumor property of DAS was tested in Swiss albino mice in the two stage initiation-promotion mouse skin carcinogenesis. Skin cancers were initiated topically with a single subcarcinogenic dose (52 micrograms) of 7, 12-dimethyl benz (a) anthracene (DMBA). Promotion was performed by twice weekly applications of 12-O-tetradecanoyl phorbol-13-acetate (TPA) at a dose of 5 micrograms/animal for 32 weeks. DAS was applied topically (250 micrograms/animal) thrice weekly for 3 weeks for anti-initiating and 1 h prior to each promotion treatment for anti-promoting studies. The results showed that the treatment schedule of DAS can effectively delay the onset of tumorigenesis and reduce the cumulative number of tumors and the average number of tumors per mouse. In groups in which DAS applied prior to initiation or promotion, a significant population of the animals remained tumor-free till the termination of experiment. These findings suggest that DAS can effectively inhibit chemically induced mouse skin carcinogenesis.

Administration, Topical↗
PubMed1998

A retrospective serological survey of humans in India for Wanowrie virus.

Wanowrie virus (WAN) is an ungrouped arbovirus having morphogenetic characters in common with Bunyavirus. It was isolated for the first time from ticks, Hyalomma marginatum isacci (6700 strain) and subsequently from a human case (68923 strain). In the absence of any reports on the prevalence of this virus amongst humans in India, 600 human sera were tested in the Complement Fixation (CF) test against both the strains of WAN virus. One hundred human sera were randomly selected from six different states, viz Jammu and Kashmir, Rajasthan, Orissa, Maharashtra, Karnataka and Tamil Nadu. CF antibodies were detected in 77 sera (12.8%) against the 6700 antigen while 91 sera (15.1%) possessed antibodies against the 68923 antigen; 60 sera were found to be reactive against both the antigens, with almost identical titres. There was no statistical difference in the distribution of CF reactive sera with respect to age, gender and geographic locations. All the CF reactive sera were found to be negative when tested in the neutralization test against the respective virus strains. The CF antibodies detected in these sera may have been produced during exposure to an antigenically closely related virus yet to be identified.

Adolescent↗
PubMed1997

Postnatal efficacy of antioxidants in the detoxification pathway of suckling neonates and lactating mice.

This study evaluates the comparative efficacy of antioxidant vitamins (ascorbic acid and alpha-tocopherol) and non-vitamin antioxidants (glutathione, cysteine and L-2-oxothiazolidine-4-carboxylate (OTZ)) in modulating the detoxification pathway of lactating dams and suckling murine pups. In dams, 100 mg/kg b.w./day treatment of each of the vitamin and non-vitamin antioxidants induced a significant increase in the hepatic level of acid soluble sulfhydryl (-SH) compared to the modulating efficiency of OTZ, glutathione and alpha-tocopherol in the kidney tissue. In the liver and kidney tissues of suckling pups OTZ and alpha-tocopherol were effective in modulating the -SH level. A statistically significant increase in the hepatic glutathione-S-transferase (GST) level was observed by OTZ, glutathione and alpha-tocopherol, while only OTZ was effective in the kidney tissue of dams and pups. In the murine system, the modulation of cellular GST/GSH status, specifically by OTZ, alpha-tocopherol and interacting antioxidant pool, may potentially ameliorate the pathophysiology of oxidative stress.

Animals↗
PubMed1997

Simplified screening for microalbuminuria.

BACKGROUND: Screening for microalbuminuria is increasingly advocated as a way to diagnose early renal involvement in diabetes and other diseases. It usually entails the use of a radioimmunoassay that is expensive and not always readily available. OBJECTIVE: To assess the efficacy of three simple and inexpensive tests for ruling out microalbuminuria. DESIGN: Cross-sectional study. SETTING: Outpatient clinics. PATIENTS: 221 patients from primary care clinics and a diabetes clinic. MEASUREMENTS: Random urine specimens were tested for albumin by using Micral-Test immunoassay strips (Boehringer Mannheim, Mannheim, Germany) and for protein by using sulfosalicylic acid testing and impregnated dipsticks (Chemstrips, Boehringer Mannheim). Radioimmunoassay for albumin was used for all specimens as standard for comparison. RESULTS: When less than 20 mg/L was considered the upper limit of normal for albumin concentration, Micral-Test, sulfosalicylic acid testing, and Chemstrips had negative predictive values of 99%, 95%, and 96%, respectively. Seventy-four specimens tested negative on both sulfosalicylic acid and Chemstrips; the negative predictive value of these two tests combined was 99%. CONCLUSIONS: The combination of sulfosalicylic acid testing and Chemistrips was as good as and less expensive than Micral-Test in ruling out microalbuminuria.

Albuminuria↗
PubMed1997

Modulatory potential of smokeless tobacco on the garlic, mace or black mustard-altered hepatic detoxication system enzymes, sulfhydryl content and lipid peroxidation in murine system.

The present study evaluates the potential of smokeless tobacco to modify the chemopreventive efficacy of minor dietary constituents, including garlic, mace or black mustard, via modulating the competing pathways of hepatic detoxication system and antioxidant defense mechanism in murine system. Garlic (100 mg/kg b.w. per day) by gavage and mace (1% w/w) or black mustard (1% w/w) in diet induced a significant increase in the levels of glutathione-S-transferase (GST), acid-soluble sulfhydryl (-SH), cytochrome b5 (Cyt.b5) and cytochrome P-450 (Cyt.P-450) in murine liver. The hepatic levels of GST and -SH were significantly depressed whereas microsomal Cyt.b5, Cyt.P-450 and MDA levels were elevated in groups treated with smokeless tobacco (50 or 100 mg/kg b.w. per day). The data revealed the inhibitory potential of smokeless tobacco on garlic-induced hepatic GST/GSH system besides the significant augmentation by smokeless tobacco on garlic or mace or black mustard-induced microsomal cytochromes. The possible implications of modulation in competing bioactivation and detoxication pathways in the process of chemical carcinogenesis are discussed.

Animals↗
PubMed1997

Modulatory influence of arecoline on the phytic acid-altered hepatic biotransformation system enzymes, sulfhydryl content and lipid peroxidation in a murine system.

The potential of arecoline alkaloid, by direct or translactational exposure, to modify the chemopreventive efficacy of phytic acid, via modulation of hepatic biotransformation system enzymes and antioxidant defence mechanism, was assessed in a murine system. Phytic acid (500 or 1000 mg/kg b.w. per day) induced a statistically significant increase in the hepatic levels of glutathione S-transferase (GST) and sulfhydryl (-SH) in murine females and suckling neonates. The elevated levels of hepatic cytochrome b5 (Cyt. b5), cytochrome P-450 (Cyt. P-450) and the depleted level of malondialdehyde (MDA) were observed in the lactating mice. Arecoline (20 mg/kg b.w. per day) alone did not modulate the hepatic GST and -SH levels although it induced a statistically significant increase in the levels of Cyt. b5, Cyt. P-450 and MDA in the murine system. Phytic acid-modulated hepatic levels of phase II components were depressed whereas phase I enzymes and lipid peroxides were further elevated by arecoline-plus-phytic acid treatment. The implications of direct or translactational modulation in the competing potential pathways of biotransformation system enzymes in the process of chemical carcinogenesis are discussed.

Animals↗
PubMed1997

Polychlorinated biphenyl congener 153-induced ultrastructural alterations in rat liver: a quantitative study.

Alterations in the liver of male and female Sprague-Dawley rats fed PCB congener 153 (2,2',4,4',5,5'-hexachlorobiphenyl) at 0.5, 5, or 50 ppm concentrations in diets for 13 weeks were determined morphometrically. A dose-dependent increase in hepatocyte volume was detected; the cytoplasmic compartment contributed to the increase in cell volume in an overwhelming fashion. Eighty percent and 250% increase in smooth endoplasmic reticulum volume and its surface area in hepatocytes were estimated in animals of both genders from 5- and 50-ppm groups, respectively; the organelle played the largest part in the increase in cytoplasmic volume. Rough endoplasmic reticulum alteration was shown to depend on gender, where the volume per hepatocyte was augmented by 40% and 45% in females of 5- and 50-ppm groups, respectively, however, 30% and 20% decreases in volume of this organelle were noted in males at those congener concentrations. A decrease of 13% in normal mitochondria volume at 50 ppm concentration was observed, which may have been a consequence of a transformation of these mitochondria to abnormal types. Two types of abnormal mitochondria, named Type I and Type II, were defined: the former comprised mitochondria that had cristae which laying parallel to the long axis of the organelle and the latter showed C- or ring-shaped profiles. Data analysis revealed a trend toward an increase in abnormal mitochondria volume in the cells as the congener concentration elevated. In addition, a threefold increase in the volume of lysosomal elements per hepatocyte was noted in 50 ppm PCB-fed rats of both genders. Also, a significant increase in peroxisome volume per cell in female rats was detected at a lower concentration than it was in the male. This study, which is a first ultrastructural quantitative investigation on the effects of a PCB that included many parameters. The methodology, and the data may prove useful to provide better understanding of pathology in the evaluation and regulation of toxic chemicals.

Animals↗
PubMed1997

Risk factors for vascular thrombosis in pediatric renal transplantation: a special report of the North American Pediatric Renal Transplant Cooperative Study.

Vascular thrombosis remains a major cause of graft failure, accounting for 12.2% of failed index transplants and 19.2% of repeat transplants. We conducted a special study to identify the risk factors for vascular thrombosis. A total of 4394 transplants (2060 living donor [LD] transplants and 2334 cadaver donor [CAD] source transplants) were evaluated. The respective vascular thrombosis rates for LD and CAD transplants were 38/2060 (1.8%) and 100/2334 (4.2%) (P<0.001). Univariate analysis showed that the rate of graft loss due to thrombosis was significantly higher in younger children (less than 2 years of age) as compared with older age groups (2-5 years, 6-12 years, and more than 12 years of age) (9.0% vs. 5.5%, 4.4%, and 3.5% for CAD transplant recipients and 3.5% vs. 3.4%, 0.7%, and 1.9% for LD graft recipients). Recipients of kidneys from cadaver donors less than 5 years of age had a significantly higher thrombosis rate (8.3%) than did recipients from older donor groups (5-10 years, 4.5%; greater than 10 years, 3.2%). Recipients of kidneys with cold ischemia time greater than 24 hr also had a higher thrombosis rate (5.6%), as compared with recipients of kidneys with a shorter cold ischemia time (3.2%). Recipients of antilymphocyte therapy on day 0 or day 1 were at dimished risk of graft loss due to thrombosis (2.2% vs. 4.1%, P=0.001). Comparable trends were seen for both LD and CAD organ recipients. LD organ recipients with a history of prior transplantation had a significantly higher rate of thrombosis as compared with those who received a primary transplant (4.6% vs. 1.6%, P=0.005). For both LD and CAD organ recipients, the occurrence of acute tubular necrosis was a significnat risk factor for the development of thrombosis. Regression analysis showed that for LD organ recipients, a history of prior transplantation increased the risk for thrombosis, whereas increasing recipient age had a linear decreasing risk effect. The use of antilymphocyte antibody or cyclosporine on day 0/1 decreased the risk for thrombosis. For CAD kidney recipients, organ cold ischemia time greater than 24 hr increased the risk for thrombosis. The use of antibody induction therapy, donors greater than 5 years of age, and increasing recipient age were factors that decreased the risk for thrombosis.

Age Factors↗
PubMed1997

Severe falciparum malaria with hyperparasitaemia treated with intravenous artesunate.

We report a 57-year-old man with falciparum malaria contracted in Kenya who presented with a three-day history of symptoms. Despite prompt treatment with quinine and artesunate and rapid clearing of the parasitaemia, he developed multiple complications and died 28 days after presentation. This case illustrates the potential for malaria to be fatal despite appropriate treatment and is one of the first reports of the use of artesunate in a hospital in a developed country.

Antimalarials↗
PubMed1997

Porcine lingual taste buds: a quantitative study.

BACKGROUND: Taste buds on the pig tongue have been neither studied in detail nor quantified. We have counted the numbers of fungiform and vallate papillae, estimated their taste bud densities, and computed numbers of taste buds per volume of papilla on porcine tongue. Pig was chosen for this work because it is an omnivorous animal, and is one of the better models for study of nutrition-related problems in omnivorous human beings. METHODS: Tongues from three adult pigs were obtained from the local abattoir, fixed in 10% neutral buffered formalin, and mapped for the fungiform and vallate papillae. Serial 15 microns sections were prepared from blocks containing the papillae, and were stained by H & E. Density and volume of the taste buds were estimated using a Bioquant system. RESULTS: Eight hundred fifty and 826 fungiform papillae were observed on tongue I and II, respectively; numerically vallate papillae were 1, 2, and 2 for tongue I, II and III, respectively. Number of taste buds per fungiform papilla was considerably less on the dorsal surface of the tongue (3.88/papilla) than on the lateral side (22.11/papilla). Vallate papillae contained significantly more taste buds, a mean of 732.67 per papilla (t = 14.27; df = 6; P = < 0.05), than in the fungiform papillae. Density of the buds per volume of fungiform papilla was notably less on the dorsum (13.69) than on the lateral border (30.08). The density of vallate papillae taste buds per volume of the papilla was significantly greater than the lateral and dorsal papillae taste bud density (t = 4.28; df = 6; P < or = 0.05). CONCLUSIONS: The present results are relevant to studies on variations of taste sensitivity among regions of the tongue.

Animals↗
PubMed1997

Pharmacokinetics of bupropion and its metabolites in cigarette smokers versus nonsmokers.

Bupropion is an antidepressant agent that is also effective as an aid to quit cigarette smoking. A single 150-mg tablet of sustained-release bupropion hydrochloride was administered to two groups of volunteers, cigarette smokers and nonsmokers, who were matched for race, gender, body frame, age, and weight. Pharmacokinetic parameters were calculated for bupropion, and three major metabolites (hydroxybupropion and the aminoalcohol isomers, threohydrobupropion and erythrohydrobupropion, expressed as a composite total). Mean (+/-SD) values of area under the concentration-time curve from time 0 extrapolated to infinity (AUC0-infinity), maximum concentration (Cmax), time to reach Cmax (tmax), and half-life (t1/2) of bupropion in smokers and nonsmokers, respectively, were 1,164 +/- 220 ng.hr/mL and 1,161 +/- 292 ng.hr/mL; 144 +/- 28 ng/mL and 143 +/- 39 ng/mL; 3.00 +/- 0.50 hours and 2.88 +/- 0.49 hours; and 19 +/- 5 hours and 18 +/- 3 hours. No clinically significant differences between smokers and nonsmokers or between male and female volunteers were observed for the pharmacokinetics of bupropion or its metabolites. The absence of pharmacokinetic differences indicates that dosage adjustments are not necessary when bupropion is prescribed to male and female cigarette smokers.

Adolescent↗
PubMed1997

Cocaine detoxification by human plasma butyrylcholinesterase.

The ability of human plasma butyrylcholinesterase (BChE) to detoxify cocaine in vivo was evaluated. Intravenous administration of BChE, at doses sufficient to increase the plasma levels of the enzyme as much as 800-fold, produced no adverse effects on the cardiovascular, autonomic, or central nervous systems of rats. Most of the enzyme could be recovered in the plasma immediately after administration and remained active with a beta-t(1/2) of 21.6 +/- 2.4 hr. Pretreatment of chloralose-urethane anesthetized rats with BChE, 0.1-7.8 mg/kg, decreased the hypertensive and arrhythmogenic effects produced by cocaine and increased the lethal dose of cocaine by three- to fourfold. Treatment of conscious rats with 1 and 10 mg/kg BChE decreased the incidence of seizures and deaths produced by a prior dose of cocaine (80 mg/kg, i.p.). These results suggest that BChE would provide a safe and highly efficacious treatment for cocaine intoxication.

Animals↗
PubMed1997

Therapeutic use of butyrylcholinesterase for cocaine intoxication.

The most common complications of cocaine ingestion are on the cardiovascular and central nervous systems and produce chest pain and generalized seizures. In humans, decreased levels of butyrylcholinesterase (BChE) (EC 3.1.1.8) have been associated with sustained effects of cocaine and life-threatening complications. Administration of purified human BChE has previously been demonstrated to protect against cocaine-associated cardiovascular toxicity in rats. A shift in the metabolism of cocaine as well as enhanced metabolism may be the underlying mechanism of the enzyme. Therefore, levels of the parent drug and four metabolites were determined in rat plasma after i.p. administration of a lethal cocaine dose, followed by i.v. administration of BChE. Plasma and brain concentrations of cocaine were lowered by 80% after BChE administration. Furthermore, the metabolic profile of cocaine in the plasma was altered. The concentration of ecgonine methylester was doubled although the concentration of ecgonine, a secondary metabolite of cocaine, was reduced. The level of benzoylecgonine was reduced by one-half while norcocaine was absent. Cocaine-associated effects upon the central nervous system were also shown to be reduced by administration of BChE to conscious rats. Furthermore, our studies in the cat have also shown that purified BChE shifts the metabolic profile of cocaine (1 mg/kg) to the pharmacologically inactive products ecgonine methylester and ecgonine. Pretreatment with BChE (0.27, 1.0, and 10.0 mg/kg) ameliorated the hypertensive effects of cocaine (1 mg/kg) by reducing the duration and the extent of BP elevation by 66%. Administration of the enzyme, 1 min after cessation of cocaine infusion, resulted in an immediate attenuation in the cocaine-induced broadening of the QRS complex. These results suggest that BChE could be an effective and rapid therapy for the treatment of life-threatening cocaine-induced cardiovascular effects in human while clearing the total body burden of cocaine.

Animals↗
PubMed1997

Lowered vaccine dose for immunisation of calves against tropical theileriosis using Theileria annulata lymphoblasts.

Bovine tropical theileriosis is of high incidence in calves below 2 months old in India. The Theileria cell culture vaccine evolved by the Punjab Agricultural University (PAU) was evaluated previously for its efficiency and safety in younger calves, both experimentally and in the field. The dose of cells used for vaccination was regulated at 1.75 to 2 x 10(6) cells. This study, which was undertaken to assess the minimum number of cells which would be effective and safer for vaccination, showed that optimal protection was given by a dose of 1 x 10(6) cells.

Animals↗
PubMed1997

Neutralising antibody and challenge response to live and inactivated avian adenovirus-1 in broilers.

Immune responses to live and inactivated avian adenovirus-1 were evaluated in broilers by neutralising antibody response and challenge reaction. The neutralising antibody titre was 1:256, 1:64 and 1:32 in live virus, inactivated virus and uninoculated control birds respectively at 3 weeks post inoculation when they were challenged. At one week post challenge the antibody titres were 1:941, 1:247 and 1:375 in live virus, inactivated virus and control birds, respectively. There was a booster effect of challenge in the live virus inoculated group up to 3 weeks post challenge. The post challenge histopathological evaluation of liver, kidneys, lungs and bursa revealed less severe changes in the live virus inoculated group as compared to other groups.

Adenoviridae Infections↗
PubMed1997

Enzymic activity of whole cells entrapped in reversed micelles. Studies on alpha-amylase and invertase in the entrapped yeast cells.

Studies have been conducted on the enzymic activity of Baker's yeast and also of Brewer's yeast entrapped into the reversed micelles formed by cetyl pyridinium chloride (CPC1) in n-hexane. The activities of alpha-amylase and invertase enzymes in the entrapped cells have been estimated and compared with those in the control experiments where there was no entrapment. The following significant observations have been made: 1. except for invertase, enzymes in Brewer's yeast, the entrapped yeast cells showed enhanced enzymic activities; 2. when the yeast cells were entrapped inside the reversed micelles along with substrates of the two enzymes, alpha-amylase, and invertase, the activity of each of these enzymes showed a further enhancement in comparison to that showed in the experiments in which substrates of the individual enzymes alone were entrapped-the phenomenon of synergism; 3. when the yeast cells and the respective substrates were entrapped inside separate reversed micelles and the solutions containing entrapped cells and entrapped substrates were mixed, the activities of the individual enzymes, alpha-amylase and invertase, showed further enhancement in comparison to the case in which the cells and the substrates were entrapped inside the same reversed micelle (in this case also the phenomenon of synergism was observed); and (4) In the case of experiments in which there was no entrapment, it was observed that the presence of substrates induced more release of enzymes from the yeast cells. These observations on yeast cells, which to the best of our knowledge have not been reported before, should be biotechnologically relevant.

Culture Media↗