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Biomedical subjects

J Leclerc

Publications and source records attributed to J Leclerc.

At least 37 records · Page 2Linked to original sources
PubMed1995

Heterogenous effects of natural flavonoids on monooxygenase activities in human and rat liver microsomes.

The in vitro effects of nine flavonoids on different monooxygenase activities from human and rat liver were investigated. Flavonoids belonging to different chemical classes [flavones (chrysin, tangeretin, flavone, 5,6-benzoflavone, 7,8-benzoflavone), flavonols (quercetin), and flavanones (pinocembrin, eriodictyol, flavanone)] were chosen. Ethoxyresorufin O-deethylase (EROD) and benzyloxyresorufin O-debenzylase (BROD) were selected as marker activities of P450 isoenzymes involved in carcinogen activation. Human EROD activity was inhibited by all flavonoids. Flavonoids without hydroxyl groups were more effective than those with hydroxyl groups. Flavonoids with an unsaturated flavone nucleus were more inhibitory than the corresponding saturated analogues. Similar structure-activity relationships were found in microsomes from methylcholanthrene-treated rats. The effects of flavonoids on human BROD activity were quite different from those observed on EROD activity. Nonhydroxylated flavones were effective activators. Hydroxylated flavonoids showed a biphasic effect, being activators at low concentrations and inhibitors at higher concentrations. The effects of flavonoids on BROD activity were rather similar in man and control rats.

Adult↗
PubMed1995

[Postoperative disorders of hemostasis caused by antifactor V circulating anticoagulant].

The case of a 34-year-old woman who experienced a biological haemostasis disorder, without clinical manifestations, is reported. The disorder was caused by a factor V inhibitor induced by a prolonged administration of antibiotics required by a postoperative biliary peritonitis. Therapeutic strategies in patients with an acquired factor V inhibitor are reviewed.

Adult↗
PubMed1995

A new thrombus imaging agent. Human recombinant fibrin binding domain labeled with In-111.

The amino-terminal domain of fibronectin has a fibrin binding site and a site for covalent cross-linking to fibrin. This fibrin binding domain was isolated from human recombinant fibronectin and labeled with In-111; the final molecular weight was 12 kD. It was applied to a pilot study of 62 patients; 30 who were thought to have deep vein thrombosis and 32 controls. All 30 patients had either impedance plethysmography, duplex ultrasound, contrast venography, or various combinations of the three. Eight disagreements in the 30 patients suspected of having deep vein thrombosis were registered between fibrin binding domain imaging and the other examinations. Three of the patients with negative scan results had clots that were 1 week old or older, and this may be a limitation of the technique. In three other patients who had negative scan results, but positive alternative studies, there was a history of previous episodes of deep vein thrombosis and this could be a cause of false-positive results in the other modalities. There was one documented false-negative scan in a fresh clot. Normal scans were obtained in the lower extremities of the control patients, except in two who demonstrated uptake at the sites of insulin injections. The initial results of this feasibility study are encouraging and warrant further investigation.

Fibronectins↗
PubMed1995

Metabolism of R-beta-hydroxypentanoate and of beta-ketopentanoate in conscious dogs.

R-beta-Hydroxypentanoate and beta-ketopentanoate are homologues of physiological ketone bodies R-beta-hydroxybutyrate and acetoacetate. They derive from the oxidation in liver of the R-moiety of R,S-1,3-pentanediol, a potential nutrient. This report documents the metabolism of R-beta-hydroxypentanoate and beta-ketopentanoate in conscious dogs. Whether administered by bolus or constant infusion, the two substrates are interconverted and rapidly metabolized. When beta-ketopentanoate was infused at a rate corresponding to 75% of the dog's caloric requirement, the steady-state total plasma concentration of the two substrates was only 1.3 mM. Because the substrates are precursors of propionyl-CoA, we assayed the urinary concentrations of markers of propionic acidemia. Their accumulation was minor compared with what is observed in patients suffering from propionic acidemia. We conclude that, at least during short-term experiments, R-beta-hydroxypentanoate and beta-ketopentanoate are well metabolized in the dog without apparent intolerance to a large supply of propionyl-CoA.

Acyl Coenzyme A↗
PubMed1995

Physiologic, metabolic, and muscle fiber type characteristics of musculus uvulae in sleep apnea hypopnea syndrome and in snorers.

Upper airway dilator muscles play an important role in the pathophysiology of sleep apnea hypopnea syndrome (SAHS). The mechanical and structural characteristics of these muscles remain unknown. The aim of this study was to compare the physiologic, metabolic, and fiber type characteristics of one upper airway dilator muscle (musculus uvulae, MU) in 11 SAHS and in seven nonapneic snorers. The different analyses were done on MU obtained during uvulo-palato-pharyngoplasty. Snorers and SAHS differed only in their apnea + hypopnea indices (11.5 +/- 5.9 and 34.2 +/- 14.6/h, respectively, mean +/- SD). Absolute twitch and tetanic tension production of MU was significantly greater in SAHS than in snorers while the fatigability index was similar in the two groups. Protein content and anaerobic enzyme activities of MU were significantly greater in SAHS than in snorers; no difference was observed for aerobic enzyme activities. The total muscle fiber cross-sectional area of MU was significantly higher in SAHS (2.2 +/- 0.9 mm2) than in snorers (1.1 +/- 0.7 mm2). The surface occupied by type IIA muscle fibers of MU was larger in SAHS (2.00 +/- 0.96) than in snorers (0.84 +/- 0.63 mm2). We conclude that the capacity for tension production and the anaerobic metabolic activity of MU are greater in SAHS than in snorers.

Adult↗
PubMed1994

Risk factors for cervical intraepithelial neoplasia: differences between low- and high-grade lesions.

This case-control study assesses relations of human papillomavirus (HPV) type 16 infection, sexual history, cigarette smoking, and oral contraceptive use to low- and high-grade cervical intraepithelial neoplasia (CIN). A total of 548 high-grade and 338 low-grade CIN cases and 612 controls were identified among women seen at a colposcopy clinic in Quebec, Quebec, Canada, in 1988-1989. Interviews, colposcopy, cervical scrapings, and colposcopically directed biopsies were performed. One pathologist reviewed all histologic slides. Southern blot techniques were used to assay specimens for HPV 16 DNA. Lifetime number of sexual partners was related to low- and high-grade CIN. Presence of HPV 16 DNA was associated with a 8.7-fold (95% confidence interval 5.1-15.0) elevation in estimated relative risk of high-grade CIN. Relative risk of high-grade CIN increased with amount of HPV 16 DNA (p < 0.0001). Estimated relative risk of high-grade CIN in current cigarette smokers was 2.4 (95% confidence interval 1.8-3.2) compared with never smokers and increased with number of pack-years of exposure (p < 0.0001). Long-term (6 years or more) users of oral contraceptives had an estimated relative risk of high-grade CIN of 1.9 (95% confidence interval 1.1-3.3) compared with those who never used such contraceptives. In contrast, presence of HPV 16 DNA, cigarette smoking, and oral contraceptive use showed little or no relation to low-grade CIN. Risk factors for low- and high-grade CIN may differ substantially.

Adult↗
PubMed1994

Age-associated risks of prophylactic anticoagulation in the setting of hip fracture.

PURPOSE: Controversy exists as to whether patient age, either independently or as a marker of concomitant illness or medication use, is associated with the dose or complication rate of warfarin prophylaxis. The aim of this study was to assess this relationship in patients receiving warfarin prophylaxis after hip fracture repair. PATIENTS AND METHODS: We undertook a retrospective cohort study of 215 patients 55 years of age or greater who underwent surgery for a fractured hip between January 1, 1990, and December 31, 1991, and received warfarin prophylaxis. The mean age was 78.9 (SD 9.5) years. The average daily warfarin dose, the decrease in hemoglobin in the postoperative period, and the rate of bleeding complications were assessed. RESULTS: Elderly patients required a significantly lower average daily warfarin dose than younger patients. This effect persisted even after controlling for the number of medical conditions, number of medications on admission, proportion of time the international normalized ration (INR) was in therapeutic range, and gender. Postoperative hemoglobin decrease was associated with patient age as well as with the use of antibiotics postoperatively. Factors associated with bleeding complications included a history of alcohol abuse and a smaller proportion of time spent in the targeted anticoagulant range. CONCLUSIONS: Older age itself and not as a marker for polypharmacy or increased number of medical conditions is associated with lower requirements for warfarin and a greater hemoglobin decrease postoperatively even when the proportion of time the INR fell within the therapeutic range is controlled. Advanced patient age, in this study, was not associated with an increased incidence of bleeding complications.

Age Factors↗
PubMed1994

Effects of beta-carotene and canthaxanthin on liver xenobiotic-metabolizing enzymes in the rat.

The activities of several phase I and phase II xenobiotic-metabolizing enzymes have been measured in liver microsomes and cytosol of male rats that had been fed for 15 days with diets containing beta-carotene or canthaxanthin (300 mg/kg diet) or an excess of vitamin A (70,000 IU/kg diet), or to which beta-carotene had been administered by ip injections (7 x 10 mg/kg body weight). Microsomal cytochrome P-450 and the associated NADH- and NADPH-cytochrome c reductases were assayed, as well as several phase I and phase II enzyme activities. Phase I activities were markers of the families 1, 2, 3 and 4 of P-450; phase II activities were microsomal UDP glucuronosyl transferases (UGT) and cytosolic glutathione S-transferase (GST). Canthaxanthin accumulated in liver to a much higher level than did ingested or injected beta-carotene. Canthaxanthin increased the liver content of cytochrome P-450 (control value x 1.7), and the activity of NADH-cytochrome c reductase (x 1.5), and of some P-450-dependent enzymes (ethoxy-, methoxy-, pentoxy- and benzoxyresorufin O-dealkylases; x98, x15, x6.5 and x13, respectively), but not of others (erythromycin N-demethylase, nitrosodimethylamine N-demethylase and laurate omega-hydroxylase). Phase II activities were also increased: UGT1 (x3.4), UGT2 (x1.2) and GST (x1.2). This induction profile, characterized by the very strong increase of the activity associated with P4501A1, and the co-induction of UGT1, closely resemble that of a classical inducer, 3-methylcholanthrene. By contrast, neither beta-carotene (fed or injected), nor an excess of vitamin A induced any significant variation of the enzyme activities measured.

Animals↗
PubMed1994

Detection of cytomegalovirus, Epstein-Barr virus and herpes virus-6 in patients with rheumatoid arthritis with or without Sjögren's syndrome.

The frequency of latent viral infection by cytomegalovirus (CMV), Epstein-Barr virus (EBV) and herpes virus-6 (HHV-6) was investigated in patients with RA with or without Sjögren's syndrome (SS) and in normal controls. Virus presence was determined by polymerase chain amplification of DNA isolated from peripheral blood mononuclear or polymorphonuclear cells and/or saliva-derived mononuclear/epithelial cells. Anti-viral antibodies and autoantibodies were also assayed. Patients with RA both with and without SS were found to have a significantly increased frequency of latent viral infection (two-fold higher, P = 0.035 for EBV and seven-fold higher, P = 0.018 for HHV-6) compared to normal controls but only in cells isolated from saliva. The increased frequency of virally infected cells from the saliva of patients with RA, regardless of the SS status, when compared to normal controls may reflect the ongoing inflammatory process, the impact of therapy and/or a less effective local immune responsiveness.

Aged↗
PubMed1994

Hemostatic markers in acute transient ischemic attacks.

BACKGROUND AND PURPOSE: Hemostatic abnormalities have been shown previously in stroke patients. The purpose of this study was to assess the activity of selected parameters of the coagulation system in acute reversible cerebral ischemia. METHODS: We measured fibrinopeptide A, thrombin-antithrombin III, and D-dimer in 36 patients in both the acute (< 7 days) and postacute stage (1 and 3 months) after a transient ischemic attack (TIA). The results were compared with those of 20 asymptomatic patients with a history of remote TIA and 65 age- and sex-matched controls. RESULTS: Mean fibrinopeptide A and thrombin-antithrombin III values were elevated in the acute stage after a TIA (P < .02) compared with levels at 1 month. In contrast, D-dimer was significantly increased at all three times points after the event when compared with remote TIA (P < .05) or control subjects (P < .001). No association could be found between marker levels and clinical outcome or the degree of cervical atherosclerosis as assessed by duplex ultrasonography. CONCLUSIONS: These findings suggest that after acute reversible cerebral ischemia, there is early transient activation of thrombogenesis and ongoing fibrinolysis.

Aged↗
PubMed1992

A low-molecular-weight heparinoid compared with unfractionated heparin in the prevention of deep vein thrombosis in patients with acute ischemic stroke. A randomized, double-blind study.

OBJECTIVE: To compare the relative safety and efficacy of a low-molecular-weight heparinoid (ORG 10172) with unfractionated heparin in the prevention of deep vein thrombosis in patients with acute ischemic stroke. DESIGN: Double-blind randomized trial. SETTING: Seven Canadian university-affiliated hospitals. PARTICIPANTS: Eighty-seven patients with acute ischemic stroke resulting in lower-limb paresis. INTERVENTION: Patients received either low-molecular-weight heparinoid, 750 anti-factor Xa units twice daily, or unfractionated heparin, 5000 units subcutaneously twice daily. Treatment was continued for 14 days or until hospital discharge if sooner. MEASUREMENTS: Deep vein thrombosis was diagnosed using 125I-labeled fibrinogen leg scanning and impedance plethysmography. Venography was indicated if either test was positive. Overt hemorrhage, major or minor, was assessed clinically. RESULTS: Venous thrombosis occurred in four patients (9%) given low-molecular-weight heparinoid and in 13 patients (31%) given heparin (relative risk reduction, 71%; 95% CI, 16% to 93%. The corresponding rates for proximal vein thrombosis were 4% and 12%, respectively (relative risk reduction, 63%; P greater than 0.2). The incidence of hemorrhage was 2% in both groups. CONCLUSION: Low-molecular-weight heparinoid, given in a fixed dose of 750 anti-factor Xa units subcutaneously twice daily, is more effective than subcutaneous low-dose heparin for the prevention of deep vein thrombosis in patients with acute ischemic stroke.

Acute Disease↗
PubMed1992

Radioimmunodetection of human bladder tumor xenografts in nude mice with radiolabeled monoclonal antibodies.

The tumor targeting potential of two monoclonal antibodies (mAbs) reacting with growth-regulated surface glycoproteins of human bladder cancer was investigated. The mAb T16 reacts more intensely with stationary cells while the mAb T43 is preferentially reactive with exponentially growing cells. The test target was T24 human bladder cancer cells grown subcutaneously in 30 nude mice. Controls for tumor specificity were human lung cancer cells grown on the contralateral side. Purified mAb's T16 and T43, and Om5, a non-reactive control, were radiolabeled with 131-Iodine and injected intravenously in doses ranging from 50 to 300 microCi in tumor-bearing animals. Consistent images of the bladder cancer xenografts were obtained at 48 and 72 hours with tumors as small as 0.1 gm. High resolution tumor images were obtained only with the reactive antibodies and according to their in vitro specificity. These results demonstrate that the two mAbs T16 and T43 can specifically and sensitively localize human bladder cancer cells in vivo.

Animals↗
PubMed1992

The low molecular weight heparin Enoxaparin inhibits the consumption of factor VII and prothrombin activation in vivo associated with elective knee replacement surgery.

Patients over 40 years of age who undergo elective orthopaedic surgery have a relatively high risk for developing post-surgical deep vein thrombosis (DVT). Prophylactic use of heparin or low molecular weight heparins can reduce the incidence of post-operative DVT by up to 80%. It is not known whether prophylaxis is achieved by inhibition of prothrombin activation or catalysis of thrombin inhibition in vivo. We determined the changes in concentrations of factor VII zymogen and thrombin-antithrombin III (the latter as an index of prothrombin activation) in the plasmas of 129 patients randomized to receive two daily subcutaneous injections of placebo or 30 mg of Enoxaparin after elective knee surgery. Enoxaparin reduced the frequency of post-surgical DVT by 70%. The concentration of factor VII zymogen had decreased by approximately 50% within 24 h after the knee surgery, followed by a gradual increase to near presurgical values. Additionally, post-Enoxaparin plasmas had statistically significant higher concentrations of factor VII zymogen than post-placebo plasmas. Post-Enoxaparin plasmas had significantly lower concentrations of endogenous thrombin-antithrombin III than comparable post-placebo plasmas. Finally, post-Enoxaparin plasmas inactivated exogenous factor Xa and thrombin more effectively than comparable post-placebo plasmas. As Enoxaparin moderated the generation of endogenous thrombin-antithrombin III after elective knee surgery, inhibition of prothrombin activation in vivo by Enoxaparin may be important for its prophylactic antithrombotic effect.

Adult↗
PubMed1991

Prevention of deep vein thrombosis after elective hip surgery. A randomized trial comparing low molecular weight heparin with standard unfractionated heparin.

OBJECTIVE: To determine the relative efficacy and safety of low molecular weight (LMW) heparin (Enoxaparin) compared with standard calcium heparin for the prevention of postoperative deep vein thrombosis in patients undergoing elective hip surgery. DESIGN: A double-blind, randomized, controlled trial. PATIENTS: Six hundred sixty-five consecutive patients undergoing hip replacement at five participating hospitals. INTERVENTIONS: Patients received either fixed-dose LMW heparin, 30 mg subcutaneously twice daily, or fixed-dose standard calcium heparin, 7500 units subcutaneously twice daily; both regimens were started 12 to 24 hours after surgery and continued for 14 days or until discharge if sooner. MEASUREMENTS: All patients had postoperative I-125-fibrinogen leg scanning and impedance plethysmography. If results of one or both tests were positive, then venography was done. Otherwise, venography was done between day 10 and day 14, or sooner if the patient was ready for discharge. RESULTS: Evaluable venograms were obtained in 258 of the 333 patients randomly assigned to receive LMW heparin and in 263 of the 332 patients assigned to receive calcium heparin. For patients with evaluable venograms, thrombosis was detected in 50 patients (19.4%) who received LMW heparin compared with 61 patients (23.2%) who received standard heparin (difference, -3.8%; 95% CI, -11.1% to 3.6%) (P greater than 0.2). Proximal deep vein thrombosis was detected in 5.4% of the patients receiving LMW heparin and in 6.5% of the patients receiving standard heparin (difference, -1.1%; CI, - 5.2% to 3.3%) (P greater than 0.2). For the entire group of 665 patients, venous thrombosis occurred in 17.1% given LMW heparin and in 19.0% given standard heparin. Hemorrhagic complications occurred in 31 patients (9.3%) given standard heparin and in 17 patients (5.1%) given LMW heparin (difference, 4.2%; CI, 0.3% to 8.2%) (P = 0.035). The relative risk reduction was 45%. The rate of major bleeding in the standard heparin group was 5.7% compared with 3.3% in the LMW heparin group (difference, 2.4%; CI, -1.0% to 5.4%) (P = 0.13). The relative risk reduction was 42%. CONCLUSION: Low molecular weight heparin is significantly less hemorrhagic than standard unfractionated heparin; the difference in the rate of deep vein thrombosis, although not statistically significant (P greater than 0.2), favors the use of LMW heparin.

Adult↗
PubMed1989

Effects of protein level, methionine supplementation and carbohydrate type of the diet on liver lipid and plasma free threonine contents in the lactating rat.

Eight groups of 13-15 female rats were fed purified diets after littering. Four groups received a low protein (8% casein) diet (groups 8) and the others, a normal protein (20% casein) diet (groups 20). Carbohydrates were supplied either as starch (groups S) or as starch plus 40% fructose (groups F). Half the animals received a 0.4% methionine supplementation (groups M). Four or five dams per group were sacrificed on days 2, 7 and 14 after littering. The diet intake was increased by methionine supplementation, substitution of starch for fructose and increased protein content, mainly during the second week of lactation. This influenced weight variation of the dams and litter growth. On all days, the plasma levels of cholesterol esters, triglycerides and phospholipids were positively correlated with the dietary protein level. On days 7 and 14, the liver neutral lipid content was increased in rats fed the low protein diets supplemented with methionine (groups 8SM and 8FM) and the normal protein diets containing 40% fructose (groups 20F and 20FM). The plasma free threonine content was positively correlated with the protein level in the diet. On day 14, rats fed a low protein diet had a threonine deficiency, except those in groups 8S and 8F. The plasma free threonine content of these rats was not reduced, possibly due to an impaired utilization of this amino acid. The liver lipidosis observed during lactation, in contrast to that observed during growth with a low protein diet, was not due to a threonine deficiency.

Animals↗