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Biomedical subjects

D Roy

Publications and source records attributed to D Roy.

At least 253 records · Page 14Linked to original sources
PubMed1990

Uncoupling of growth and acids production in Bifidobacterium ssp.

Kinetics of batch cultivation of four species of Bifidobacterium in milk were examined in detail. Bifidobacteria could grow well in milk inoculated with cultures prepared in a synthetic medium. Cessation of growth occurred, however, in pH-controlled batch cultures, although incomplete utilization of lactose was observed. Lactate and acetate accumulation caused limitation on growth of bifidobacteria leading to an uncoupling of biomass and product formation. From 70 to 75% of both final lactate and acetate concentrations were produced during the stationary growth phase of Bifidobacterium bifidum, Bifidobacterium breve, and Bifidobacterium longum cultivated in milk, whereas Bifidobacterium infantis produced less acetate or lactate during this phase.

Acetates↗
PubMed1990

Efficiency of sanitizing agents for destroying Listeria monocytogenes on contaminated surfaces.

In an effort to control the potential hazard of dairy product contamination by contact with processing surfaces, the efficiency of four commercial sanitizing agents was evaluated using the AOAC use-dilution method for their bactericidal activity at 4 and 20 degrees C against Listeria monocytogenes strain Scott-A attached on four types of surfaces (stainless steel, glass, polypropylene, and rubber). Our results indicate that all sanitizers tested were more efficient against L. monocytogenes attached to nonporous surfaces than to porous surfaces. After 10 min of contact time, the limit concentration of disinfectants was at least 5 to 10 times higher for sanitizing rubber than stainless steel or glass surfaces. Concentrations of each sanitizer needed to be higher at sanitation at 4 degrees C than at 20 degrees C to destroy L. monocytogenes attached to stainless steel, glass and rubber when surface contamination was achieved at 4 or 20 degrees C.

Disinfection↗
PubMed1990

Cytochrome P-450 catalyzed redox cycling of orthophenylphenol.

o-Phenylphenol was converted to 2,5-dihydroxy biphenyl (phenylhydroquinone) by microsomal P-450. Depending on the cofactor used, microsomal enzymes catalyzed oxidation and/or reduction of phenylhydroquinone. Phenylhydroquinone was oxidized to phenyl 2,5'-p-quinone by cumene hydroperoxide-supported microsomal P-450. Phenyl 2,5'-p-quinone was reduced to phenylhydroquinone by cytochrome P-450 reductase. This study provides direct evidence of cytochrome P-450 catalyzed redox cycling of o-phenylphenol. It is postulated that redox cycling of o-phenylphenol may play a role in o-phenylphenol-caused bladder cancer.

Animals↗
PubMed1990

Role of angioplasty in the treatment of symptomatic vascular spasm occurring in the post-operative course of intracranial ruptured aneurysms.

Angioplasty of vascular spasm (VS), related to subarachnoid hemorrhage (SAH) has been recently introduced to the medical field. The authors report 5 cases treated by this mean in the postoperative period. These patients were all symptomatic from their VS inspite of early surgery and of the preventive treatment by Nimodipine. In all cases, obtained increase in the caliber of the spastic vessels was followed by a rapid clinical improvement coupled with a significant decline of the flow rates as confirmed by transcranial Doppler (TCD). No recurrence of VS has been observed. This technique appears quite effective provided that it is performed as early as the clinical symptoms come out in correlation with important acceleration of flow rates on TCD.

Adult↗
PubMed1990

Detergent-induced changes in the protein constituents of various cell types of opercular epidermis of Rita rita.

Fish (Rita rita) were exposed to an anionic detergent, dodecylbenzene sodium sulfonate, at a concentration of 6.9 mg/liter (96-hr LC50 of the detergent). A series of histochemical techniques, used in this study for the demonstration of various protein constituents, indicated a gradual decrease in the intensity of staining reactions of the cytoplasmic material, suggesting a loss of protein moieties from the club cells and the epithelial cells of the opercular epidermis as a result of detergent exposure.

Animals↗
PubMed1990

Dural fistulae of the tentorium cerebelli. Radioanatomical, clinical and therapeutic considerations.

Among the 84 intracranial dural fistulae treated in the Neuroradiology department of the University Hospital Centre of Nancy between August 1983 and April 1990, 10 (11.9%) were located on the tentorium cerebelli. The patients were 7 men and 3 women aged from 41 to 61 years at the time of diagnosis. All tentorial dural fistulae showed an exclusively cortical drainage, and only one of them was associated with probable thrombosis of a major sinus. Nine patients presented with at least one episode of neurological deficit (including 2 with progressive ascending myelopathy) associated with a cerebro-meningeal haemorrhage in 6 cases. In all patients the initial treatment was an endovascular one, subsequently reinforced by surgery in 2 patients. In every case the clinical condition was improved or stabilized and no recurrent haemorrhage was observed, but radioanatomical cure was obtained in only 3 patients: 1 treated by the endovascular route and 2 by embolization combined with surgery. The anatomical, physiopathological and clinical aspects of these particular fistulae and the different possible therapeutic approaches are discussed.

Adult↗
PubMed1990

Covalent binding of phenytoin to protein and modulation of phenytoin metabolism by thiols in A/J mouse liver microsomes.

The role of thiols (nonprotein and protein) in the metabolic activation of phenytoin was examined. In vitro phenytoin covalent binding and metabolite formation were determined in hepatic microsomes from A/J mice. Covalent binding of a phenytoin-reactive intermediate to microsomal protein was linear with respect to time, protein concentration and phenytoin concentration. Covalent binding was inhibited by inhibitors of cytochrome P-450. Inducers of cytochrome P-450 enhanced phenytoin covalent binding as follows: phenobarbital greater than 3-methylcholanthrene greater than saline-treated controls. Low molecular weight thiols (GSH, cysteine and cysteamine), a thiol generator (methylthiazolidine carboxylate), and thiol modifying agents (N-ethylmaleimide, mercuric chloride and diamide) significantly inhibited covalent binding. Amino acids other than cysteine did not decrease the covalent binding. Formation of the metabolites, para-hydroxyphenytoin and phenytoin dihydrodiol, was greater following preincubation with GSH or cysteine. In summary, protein thiol groups appear to be important sites for in vitro covalent binding of a reactive intermediate of phenytoin. These data suggest glutathione may protect membrane-bound enzymes responsible for phenytoin metabolism from attack by an electrophilic or free radical reactive intermediate of phenytoin and GSH may inactivate a phenytoin-reactive metabolite by formation of a putative glutathione conjugate.

Amino Acids↗
PubMed1990

Surgical treatment of the Wolff-Parkinson-White syndrome. Endocardial versus epicardial approach.

From 1983 to 1988, 51 patients with the Wolff-Parkinson-White syndrome underwent surgical ablation of an accessory conduction pathway, 25 by the classic endocardial approach and 26 by the epicardial technique supplemented by cryosurgery. In the endocardial and epicardial groups, the accessory pathway was in the left free wall in 22 and 18 patients, respectively, posterior septal in two and seven, and in the right free wall in one patient in each group. There was no early or late death in the endocardial group, and postoperative complications developed in five patients (20%). Pathway ablation was completely successful in 22 patients (88%), preexcitation recurred in two patients (8%), and one had recurrence of supraventricular tachycardia (4%). One of the failures occurred with a posterior septal pathway (50%), and the two others with a left free-wall pathway (9%). With the epicardial technique, there were no early deaths and one late death caused by atherosclerotic coronary artery disease. Five patients (19%) had postoperative complications. The pathway was ablated successfully in 22 patients (85%), preexcitation recurred in three patients (12%), and supraventricular tachycardia remained inducible in another patient despite disappearance of the delta wave. Three of those failures occurred with anterior left free-wall pathways (16%), but only one patient had recurrent supraventricular tachycardia (4%) requiring immediate reoperation, which was successful. In conclusion, although epicardial or endocardial approaches produced similar results, our observations suggest that left free-wall accessory pathways located high anteriorly may be ablated in a more reproducible way with the endocardial technique, whereas the epicardial approach appears easier for posterior septal pathways. We therefore believe that any surgeon beginning such surgery should be aware of the possibilities and limitations of each of the two techniques.

Adolescent↗
PubMed1989

Changes in activities of free radical detoxifying enzymes in kidneys of male Syrian hamsters treated with estradiol.

Target organ-specific estrogen-induced DNA adducts were previously shown to precede renal carcinogenesis in Syrian hamsters. Because estrogens induced these DNA modifications, but were not part of the adduct structure, free radical activation of endogenous electrophiles was postulated as a mechanism of tumor induction by estrogens. In the present study, the activities of enzymes which detoxify reactive intermediates were studied in liver and kidney of hamsters treated with estradiol for 1, 2, and 4 mo and in untreated controls. These studies were done to detect oxidative stress in the target organ of carcinogenesis. In the estrogen-exposed hamster kidney (1, 2, and 4 mo), activities of glutathione peroxidases I and II were significantly increased. The activity of catalase was decreased compared to those in untreated controls. In livers which are not the target organ of carcinogenesis, treatment of hamsters with estrogen for 1, 2, and 4 mo resulted in changes of activities of glutathione peroxidases I and II and catalase, which were opposite to the pattern found in the kidney. Activities of superoxide dismutase, glutathione reductase, glucose-6-phosphate dehydrogenase, gamma-glutamyl transpeptidase, and glutathione transferase in estradiol-treated hamster liver and kidney did not differ significantly from those in either liver or kidney of untreated age-matched controls. Fluorescent products of lipid peroxidation more than doubled in the kidney, but not in the liver of hamsters treated with estradiol for 1 mo. It is concluded that the increases in glutathione, in the activity of glutathione peroxidase, and in products of lipid peroxidation in the kidneys of hamsters treated chronically with estrogen all point towards elevated levels of oxidative stress.

Animals↗
PubMed1989

Comparison of assays for catechol estrogen synthase activity: product isolation vs radioenzymatic catechol-O-methyltransferase-coupled procedures.

Reported values for the activity of enzymes mediating catechol estrogen formation by hamster kidney and liver, measured by catechol-O-methyltransferase-coupled radioenzymatic assay, have been uniformly low and there have been marked discrepancies in values reported from different laboratories. Therefore, we examined the validity of the radioenzymatic assay used in these studies. NADPH-dependent estrogen 2- and 4-hydroxylase activity of hamster liver microsomes measured by radioenzymatic assay was comparable to that reported in the literature but at least one order of magnitude lower than that obtained with a direct product isolation assay. Several features of the radioenzymatic assay were identified which, together, contribute to the underestimation of enzyme activity. They include, incomplete protection from oxidative degradation of both the catechol estrogens generated and of the catechol-O-methyltransferase and assay conditions which are suboptimal for O-methylation of the catechol estrogens. We conclude that results obtained using the catechol-O-methyltransferase-based radioenzymatic assay can only be considered valid if a consistent stoichiometric relationship can be demonstrated between the amounts of catechol estrogens and their O-methylated products.

Animals↗
PubMed1989

Detergent-induced changes in the mapping of certain enzymes in various cell types of Rita rita. I. Opercular epidermis.

The different cell types in the opercular epidermis of Rita rita when exposed to a synthetic detergent, dodecylbenzene sodium sulfonate in the concentration of 6.9 mg liter-1 (96-hr LC50 of the detergent), had a gradual decrease in the activity of various enzymes responsible for different metabolic processes occurring inside the cell. After a certain period of detergent exposure, the activities of all the enzymes in these cells are completely inhibited.

Animals↗
PubMed1989

Detergent-induced changes in the mapping of certain enzymes in various cell types of Rita rita. II. Gill epithelium.

Rita rita were exposed to 6.9 mg/liter (96-hr LC50 of an anionic detergent, dodecylbenzene sodium sulfonate). Loss of activity of certain enzymes responsible for various metabolic processes in fish gill epithelium was observed using a battery of histochemical techniques. The information of this investigation may possibly add to an understanding of the as yet unknown mechanism of detergent action.

Animals↗
PubMed1989

UV laser photodamage to whole lenses.

Lenses from rat or calf were exposed in vitro to UV radiation from a nitrogen laser operated at 337.1 nm or from an excimer laser operated at 3.8 nm. Visible light transmission was monitored during calf lens irradiations at 308 nm and found to decrease. Proteins were extracted from the irradiated rat or calf lenses, separated into water soluble and insoluble fractions, and analysed using SDS-PAGE. Comparison of these gels with dark controls showed that, following photolysis, there was loss of polypeptide material in the 20-30 kDa region and concomitant formation of polymers at 40 and 60 kDa, and at greater than 100 kDa in calf lens (308 nm irradiation) and rat lenses (337.1 nm irradiation) in vitro. In addition, there was evidence for formation of lower molecular weight polypeptides at 10 kDa in the protein from irradiated rat lenses. The rat SDS-PAGE gels were challenged against anti-calf gamma crystallin serum. There was clear evidence that the polymeric material, in the water insoluble protein fraction from the 337.1 nm photolyzed rat lenses was derived in part from gamma crystallin. The macromolecular changes detected in these photolyzed rat and calf lens proteins were similar to those previously reported to accompany aging in the human lens. Biochemical changes of the type observed in UV irradiated rat and calf lenses may be responsible for the loss of visible light transmission seen in calf lenses.

Animals↗
PubMed1989

Mechanism of inhibition of estrogen-induced renal carcinogenesis in male Syrian hamsters by vitamin C.

Dietary supplementation of vitamin C to diethylstilbestrol (DES)- or estradiol-treated male Syrian hamsters is known to inhibit renal carcinogenesis by approximately 50%. To elucidate the mechanism of inhibition, the influence of administration of vitamin C on a series of previously described biochemical markers of kidney carcinogenesis was investigated. Hamsters were stratified into four groups: (i) untreated controls; (ii) vitamin C-treated; (iii) estrogen-treated; and (iv) estrogen plus vitamin C-treated animals. Concomitant administration of vitamin C and diethylstilbestrol (DES) decreased concentrations of the major DES-DNA adduct by 70-90% in liver, kidney and testis than those receiving DES only. Diethylstilbestrol-4',4"-quinone has previously been shown to be the genotoxic metabolite of DES responsible for DNA adduct formation in vivo. In vitro, vitamin C reduced diethylstilbestrol-4',4"-quinone to cis- and trans-diethylstilbestrol in a dose-dependent fashion. Changes in activities of quinone reductase, catalase, superoxide dismutase and of glutathione metabolizing enzymes (glutathione peroxidase, glutathione reductase, gamma-glutamyl transpeptidase and glucose-6-phosphate dehydrogenase) in response to vitamin C were not observed or not sufficiently large to account for the 50% decrease in tumor incidence. No differences were detected in indirect estrogen-induced kidney DNA adducts in response to vitamin C treatment. It is concluded that vitamin C inhibits estrogen-induced carcinogenesis by reducing concentrations of estrogen quinone metabolites and their DNA adducts.

Animals↗
PubMed1989

Metabolic oxidation of diethylstilbestrol to diethylstilbestrol-4',4"-quinone in Syrian hamsters.

Diethylstilbestrol-4',4"-quinone (DES Q) has previously been postulated to be a reactive intermediate in diethylstilbestrol (DES) metabolism. DES is oxidized to DES Q in vitro, but the occurrence of the quinone metabolite in vivo has not yet been demonstrated due to its instability and chemical reactivity. In this report, the characteristics of in vitro formation of DES Q and the isolation of 3H-labeled DES Q from tissue extracts of hamsters injected with radiolabeled DES is described. In vitro, the time-dependent formation of DES Q as a function of microsomal protein, cofactor or substrate concentrations was demonstrated. The microsome-mediated oxidation of DES to quinone was inhibited by various compounds that also effectively inhibit the peroxidatic activity of cytochrome P-450. In vivo, the formation of DES Q occurred in all tissues investigated, livers and kidneys of male and female adult hamsters, neonates and fetuses, and in uterus and placenta. Concentrations of quinone metabolite in liver and kidney of adult hamsters after injection of 75 mumol/kg DES were 76 and 20 pmol/g tissue respectively. In neonates and fetus, concentrations of DES Q after the same dose of DES were markedly less than those in adults (0.026 and 0.047% of adult levels in neonatal liver and kidney and 0.013 and 0.016% of adult levels in fetal liver and kidney respectively). Since DES Q was also formed by fetal liver homogenate in vitro, fetal oxidizing enzymes appear to be the source of the quinone metabolite in this tissue. DES Q concentrations were also examined after injection of DES into hamsters pretreated with vitamin C or alpha-naphthoflavone, substances known to inhibit DES-induced renal carcinogenesis. Quinone metabolite levels were cut in half in response to vitamin C in correlation with the approximately 50% decrease in DES-induced renal tumors reported previously. alpha-Naphthoflavone pretreatment decreased renal and hepatic DES Q concentrations by 70 and 17% respectively, also in correlation with the known prevention of kidney tumors by this flavone. These data support a role of DES Q in DES-induced carcinogenesis. Since there is no correlation between DES Q concentrations and target site specificity of DES induced tumors, the oxidation of DES to DES Q and the genotoxicity of this metabolite may be a necessary but not sufficient event in tumor development. Hormone-dependent growth of initiated cells may also be necessary for the occurrence of cancers.

Aging↗
PubMed1989

Isocratic separation of phenytoin metabolites by high-performance liquid chromatography from human and animal microsomes and urine.

A rapid and simple high-performance liquid chromatography analytical method is described for the quantitative determination of phenytoin and five of its metabolites--phenytoin dihydrodiol, catechol, methoxycatechol, para-hydroxyphenytoin, and meta-hydroxyphenytoin--in biological materials. Following ethyl acetate extraction and incubation with beta-glucuronidase, samples were passed through a C18 Sep-Pak cartridge. The eluate was chromatographed on a reverse-phase 10 cm C18 Radial Nova-Pak (5 micron) column using a mobile phase of isopropanol:water (20:80) at a flow rate of 1.4 ml/min and monitored at 235 nm. Total chromatographic analysis time was 23 min, with complete baseline resolution of all metabolites. Five different columns and 10 different mobile phase conditions were studied to determine the best system. The 10-cm C18 Radial Nova-Pak (5 micron) gave the best resolution, reproducibility, and durability. This method should prove applicable for clinical use as well as for research purposes.

Animals↗