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Biomedical subjects

N Bernard

Publications and source records attributed to N Bernard.

At least 127 records · Page 7Linked to original sources
PubMed1987

[Episiotomy and prevention of complete and complicated tears. A study in 3 European countries].

The rates of third-degree tears in deliveries with and without episiotomy were compared in five samples: three French samples, a Belgian one and a Dutch one. Those samples corresponded to 48,430 single vaginal deliveries. The rates of episiotomy ranged from 29.3% to 54.2%. The results demonstrate that the risk of third-degree tears in vertex uncomplicated deliveries without episiotomy is low, and that in numerous cases third-degree tears are not prevented by an episiotomy. When uncomplicated deliveries of primipara were considered, results from four of the five samples showed that third-degree tears were not significantly more frequent in deliveries without episiotomy.

Belgium↗
PubMed1987

[Frequency of hepatitis B antigens in the blood of pregnant women].

In the antenatal clinics of the Hospital Foch at Suresnes we have instituted testing for hepatitis B antigens routinely of all mothers coming to the clinic so that we can look at the immune state of children born to mothers who have the hepatitis B virus and have hepatitis B antigens. The incidence of hepatitis B antigens altogether was 0.77%, which is twice as frequent as found in blood donors at the same hospital. This high incidence is found in women coming from the African and Asian continents where it is found at the same level in blood donors in the Hauts-de-Seine region. If however we examine women born in France who live in the towns the incidence is 0.32%. An enquiry in a standard medical form does not show a true risk factor. When, however, a more precise questionnaire is filled in, we found that risk factors were present in eight out of ten positive cases. We only made this enquiry on sero-positive women. When the baby was born we gave a 1 ml dose of anti-hepatitis B immunoglobulin (100 IU) followed by three injections of 1 ml of vaccine (HEVAC B Institut Pasteur) on the 1st, 30th and 60th day of life. A repeat injection was carried out when the infant was one year old. Altogether 32 newborns were treated: they tolerated the products well and it was effective because all infants developed anti-hepatitis B antibodies in every case that was followed up.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Routine analysis of catecholamines and metabolites in urine by a liquid chromatographic column switching system.

A reversed-phase liquid chromatographic technique including a column switching system has been adapted for the routine measurement of catecholamines and their metabolites (14 compounds) in urine. From 1 ml of urine all the compounds and the internal standards were obtained according to combined extraction procedures involving organic solvent, anionic and weakly cationic resins. Finally four extracts (catecholamines, methoxamines, acidic and neutral derivatives) had to be chromatographed throughout a wholly automated apparatus. For each run, the column switching system determined the analytical columns to be used to obtain the separation of the compounds from interferences due to other co-extracted endogenous substances, while the analysis times remained between 20 and 40 min. Such a system allowed the rapid clean-up of columns (in direct- and back-flush mode) carried out between two consecutive injections. By coupling on-line fluorimetric and electrochemical detections the specificity of the technique could be checked, since the ratio of the responses of both detectors was an index of the purity of the peaks. Finally the advanced automation of the equipment allowed weekly the evaluation of catecholamines and the whole range of their known metabolites in 36 urine samples.

Catecholamines↗
PubMed1985

Measurement of urinary catecholamines and their catechol metabolites and precursor by liquid chromatography with column-switching and on-line fluorimetric and electrochemical detection.

A new method is described for the determination of catecholamines and their precursor (3,4-dihydroxyphenylalanine), and separately of their catechol metabolites (3,4-dihydroxymandelic acid, 3,4-dihydroxyphenylacetic acid, 3,4-dihydroxyphenylethylene glycol and 3,4-dihydroxyphenylethanol) in urine. After a two-step pretreatment involving ethyl acetate extraction and adsorption onto alumina, the separation is performed by ion-pair reversed-phase high-performance liquid chromatography. A column-switching system enables complete separation of the most polar compounds without increase in the total analysis time. The column eluates are monitored with both fluorimetric and amperometric detectors, the relative responses of which are used as an index of peak purity. Reference values for twelve healthy adults are given.

Adult↗
PubMed1985

Pharmacokinetics of penbutolol and its metabolites in renal insufficiency.

The pharmacokinetics of penbutolol, its 4-hydroxylated metabolite and of their conjugates was studied in hypertensive patients with various degrees of renal impairment. A single oral dose of penbutolol 40 mg, was rapidly absorbed after a lag-time of 0.34 h. Its plasma concentration reached a maximum after 0.84 h and then declined bi-exponentially, with an apparent elimination half-life of 21.8 h. The hydroxylation of penbutolol was negligible and conjugation was of major importance for its elimination. Consequently, the kinetics of unchanged penbutolol were not altered by renal impairment. The 48 h-urinary excretion of penbutolol and its metabolites reached 13-14% of the administered dose, which is consistent with extensive metabolism of the drug. After treatment for 30 days with penbutolol 40 mg/d there was no accumulation of the parent drug but the concentration of its conjugates was increased. It is concluded that the dose of penbutolol need not be changed in patients with mild renal insufficiency, 4-hydroxypenbutolol is unlikely to participate in the anti-hypertensive effect of the drug, due to its low concentrations, and biotransformation of penbutolol may be enhanced during chronic treatment.

Adult↗
PubMed1984

Long term production of acute-phase proteins by adult rat hepatocytes co-cultured with another liver cell type in serum-free medium.

Three acute-phase proteins, haptoglobin, alpha 2-macroglobulin and hemopexin, as well as albumin, have been measured daily in the hydrocortisone-supplemented serum-free medium of pure and mixed cultures of adult rat hepatocytes for 5 and 20 days respectively. Whereas plasma protein production rapidly declined in pure culture, it remained relatively stable when hepatocytes were co-cultured with rat liver epithelial cells. In the latter cultures, an early stimulation of albumin and alpha 2-macroglobulin secretion was observed. In addition, four other plasma proteins, fibrinogen, alpha 1-acute-phase protein, alpha 1-acid glycoprotein and alpha 1-antitrypsin were shown by immunodiffusion to still be produced by day 20 of co-culture. These results suggest that hepatocyte co-cultures represent a suitable model for studying the mechanism which controls synthesis of plasma proteins, including acute-phase proteins by liver cells.

Albumins↗
PubMed1984

Lysine residues, but not carbohydrates, are required for the regulatory function of H on the amplification C3 convertase of complement.

Lysine epsilon-amino groups of human factor H were selectively converted to guanidino groups by treatment with 0.1 M O-methylisourea at pH 10.4. Guanidination resulted in a dose-dependent decrease in the capacity of the regulatory protein to accelerate decay dissociation of P-stabilized amplification C3 convertase sites, to serve as a co-factor for cleavage of cell-bound C3b by I, and to compete for binding of 125I-untreated H to C3b. Modification of approximately 75% lysine epsilon-amino groups suppressed 97% of H functional activity. Biochemical analysis of native H demonstrated a total carbohydrate content of 18.5% (w/w) and the presence in the molecule of 11 biantennary oligosaccharidic chains of the N-acetyl-lactosaminic type. Total desialation of H by using Clostridium perfringens neuraminidase, and total deglycosylation of desialated H by using beta-endo-N-acetylglucosaminidase resulted in a 1.5- to 2-fold increase in H activity on a weight basis. Deglycosylation did not alter the capacity of H to discriminate between activating and nonactivating surfaces of the alternative pathway. Thus, lysine residues are important determinants of the binding capacity of H for cell-bound C3b, whereas the carbohydrate portion of the molecule is not required for the regulatory function of the protein on the amplification C3 convertase.

Acetylglucosamine↗
PubMed1983

In vitro studies on some parameters of the binding of the rat hemopexin--heme complex with the hepatic membrane receptor.

The binding of [125I]Hpx--heme with the rat hepatic plasma membrane receptor was studied at 37 degrees C as well as different parameters such as plasma membrane concentration, calcium dependence, optimal pH and specific binding. A Scatchard plot revealed the existence of one binding for [125I]Hpx--heme on the isolated liver plasma membrane with a Kd = 3.2 X 10(-8) M.

Animals↗
PubMed1983

Structural studies of glycans isolated from rat plasma hemopexin.

After exhaustive pronase digestion, purification by gel filtration and affinity chromatography on concanavalin A, three glycopeptide fractions were obtained from rat hemopexin. Two fractions (I and II) were concanavalin A non-reactive and one (III) was concanavalin A reactive. On the basis of carbohydrate composition, methylation analysis and proton nuclear magnetic resonance spectroscopy, the primary structure of the glycan in fraction III is proposed as being a mixture of mono- and di-sialo-diantennae of the N-glycosidic, N- acetyllactosamine type. Hydrazinolysis of glycopeptides not binding to concanavalin A yielded mixtures of oligosaccharides for both fractions. These oligosaccharides were separated by HPLC; the molar composition of each of them is given. These data suggest that rat hemopexin contains, among others, a diantennary structure bearing three sialic acid residues.

Animals↗
PubMed1982

Pharmacokinetics of intravenous camazepam in dogs.

Free plasma concentrations were studied after i.v. administration of three different doses (2.5, 5, 7.5 mg/kg respectively) of 3-N,N-dimethylcarbamoyloxy-7-chloro-5-phenyl-1-methyl-1,3-dihydro-2H-1,4-benzodiazepin-2-one (camazepam) to three healthy male mongrel dogs. Total plasma concentration was measured by a specific gas-liquid chromatography technique. The protein binding of camazepam in dog plasma was studied by using the equilibrium dialysis method and found to vary from 88.5 to 76.7% when the total drug concentration increased from 8 ng/ml to 8 micrograms/ml. For the subsequent pharmacokinetic analysis the calculated free camazepam plasma concentrations were used. The superposition principle was applied to each dog demonstrating that a linear pharmacokinetic model was applicable. Computer analysis showed that the pharmacokinetics of camazepam could be conveniently described by a three-compartment model assuming that the drug elimination occurred from the central compartment exclusively. The half-life of the terminal elimination phase ranged from 6.4 to 10.5 h, a finding which might suggest that camazepam could exhibit long-lasting effects.

Animals↗
PubMed1980

Determination of nalidixic acid and its two major metabolites in human plasma and urine by reversed-phase high-performance liquid chromatography.

This paper describes a precise and sensitive method for analysis of nalidixic acid and its two major metabolites in plasma and urine following the oral administration of a therapeutic dose in humans. After addition of an internal standard (oxolinic acid), 1-ml samples of plasma or urine are extracted at acidic pH with chloroform. The extracts are purified by re-extraction with sodium hydroxide solution and then chloroform. The final extracts are evaporated to dryness, reconstituted in mobile phase and injected into a high-performance liquid chromatograph equipped with RP-8 column and UV detector operating at 254 nm. The limit of sensitivity of the method is lower than 0.5 micrograms/ml of plasma or urine for each compound. The applicability of the method to pharmacokinetic studies of nalidixic acid in humans is demonstrated.

Chromatography, High Pressure Liquid↗