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A Myara

Publications and source records attributed to A Myara.

35 records · Page 2Linked to original sources
PubMed1993

Choledocho-ureteral anastomosis in the rat. A new experimental model of long-term, total, internal bile diversion.

Choledocho-ureteral anastomosis is a new experimental model of total bile diversion in the rat. The anastomosis is carried out using a polyethylene tutor drain and requires neither an external drain nor restraint of the animal. After 14 days of diversion, bile flow fell by 53% and there were no biological signs of cholestasis. The rats survived for up to 2 months. Choledocho-ureteral anastomosis is a reliable and simple experimental model which can be used to study the effects of prolonged interruption of enterohepatic bile-acid circulation.

Anastomosis, Surgical↗
PubMed1993

Investigation of total and conjugated bilirubin determination during the neonatal period.

During the neonatal period, total and conjugated bilirubin determinations are necessary to identify the origin of jaundice, to predict its evolution and to treat it. We discuss the results obtained in 108 neonates (less than 15 days old), undergoing phototherapy or not, using a colorimetric diazo reaction and dual wavelength reflectance with a Kodak Ektachem analyzer. Concerning total bilirubin determination, the methods correlate well (r > 0.96). Discrepancies are observed for conjugated or "direct" bilirubin, and high performance liquid chromatography was carried out in order to explain them. The chromatograms show 4 neonate samples with only classic mono- but no di-glucurono-conjugate fractions, whereas all the neonates present two unusual fractions (I and II) not seen in adults. A correlation was found between the amount of fraction II and the conjugated bilirubin determined by diazo reaction and between fraction I and the conjugated bilirubin obtained in the Kodak Ektachem assay. A better correlation between fraction I and conjugated bilirubin on Kodak was observed (r = 0.79, vs r = 0.66) when the newborns were submitted to phototherapy. Moreover, fraction II and conjugated bilirubin measured by the diazo reaction on Hitachi 717 rose significantly. In conclusion, total bilirubin is accurately determined during the neonatal period; for conjugated or "direct" bilirubin determination, our study points out significant differences. Further investigation will determine the nature of the fractions observed by liquid chromatography in neonatal sera, and the components actually determined by the automatized methods usually employed.

Bilirubin↗
PubMed1992

Bilirubin uridine diphosphate glucuronosyltransferase hepatic activity in jaundice associated with congenital hypothyroidism.

Hepatic bilirubin uridine diphosphate glucuronosyltransferase activity was assayed in an infant with prolonged jaundice and congenital hypothyroidism before thyroid therapy. This activity was nil, suggesting a possible delayed maturation of the enzyme. Although further studies will be necessary to confirm this hypothesis, prolonged jaundice associated with congenital hypothyroidism may be due to a delayed maturation of the hepatic glucuronidation of bilirubin.

Bilirubin↗
PubMed1990

Gunn rats: a reproducible experimental model to compare the different methods of measurements of bilirubin serum concentration and to evaluate the risk of bilirubin encephalopathy.

Three groups of Gunn rats were studied: group 1 was perfused with bilirubin solution alone, group 2 was perfused with bilirubin and albumin solutions simultaneously, group 3 was perfused with bilirubin solution for 30 min then bilirubin and albumin solutions for the following 10 min. Our results indicate that (1) Gunn rats are a reliable experimental model to study the risk of bilirubin encephalopathy, (2) unbound bilirubin can enter the brain when albumin binding capacity is reduced, (3) and bilirubin binding capacity of serum for unbound unconjugated serum bilirubin is a better criterion than total serum bilirubin and erythrocyte bilirubin to evaluate the risk of kernicterus. This model could also be used to study variations of permeability of the blood-brain-barrier and influences of drugs on bilirubin metabolism.

Animals↗
PubMed1990

Effect of chronic administration of ursodeoxycholic acid on the ileal absorption of endogenous bile acids in man.

The effect of long-term administration of ursodeoxycholic acid on the ileal absorption of endogenous bile acids was determined using the tauro 23 (75Se) selena-25 homotaurocholic acid test in a controlled double-blind study involving healthy subjects (n = 15). Subjects received placebo or 13 to 15 mg/kg/day ursodeoxycholic acid for 5 wk. In the placebo group (n = 7) there was no change in the composition of serum bile acids or in the mean percentage of retention of tauro 23(75Se) selena-25 homotaurocholic acid (36.1% +/- 6.0% vs. 38.7% +/- 6.7%). In contrast, in the ursodeoxycholic acid group, serum ursodeoxycholic acid conjugates increased and the percentage of retention of tauro 23 (75Se) selena-25 homotaurocholic acid fell from 45.8% +/- 6.8% to 20.5% +/- 5.7% (p less than 0.01). We conclude that ursodeoxycholic acid administration reduces ileal absorption of endogenous bile acids. These findings provide a rational explanation for the changes in the composition of the bile acid pool during ursodeoxycholic acid therapy and could have important therapeutic implications.

Absorption↗
PubMed1990

[Comparison of three methods evaluating the saturation of serum bilirubin transporters in children with type I Crigler Najjar disease].

The assessment of reserve bilirubin binding capacity of serum in 12 children with type I Crigler-Najjar syndrome was performed by 3 biochemical methods. Two of them use chromatography techniques: thin layer on Sephadex or high performance liquid; they allow the determination of the saturation rate of all serum bilirubin carriers. The third method only evaluates the major carrier, albumin, using the molar bilirubin-albumin ratio. An identical correlation coefficient of 0.90 has been obtained when comparing with the chromatographic method on thin layer, respectively 20 determinations using high performance liquid chromatography and 122 measurements of the bilirubin/albumin ratio. In practice, we advise a first, simple and rapid determination of the bilirubin/albumin ratio in case of a sudden aggravation of the jaundice in the children with Crigler-Najjar type I disease. The chromatographic methods will be used in a second step, or in order to survey the phototherapy treatment that these children receive.

Adolescent↗
PubMed1989

High-performance liquid chromatographic determination of tauro- and glyco-conjugated bile acids in human serum.

A method for the identification and individual determination of the ten tauro- and glyco-conjugated bile acids is described. It consists in a specific three-step extraction from small serum samples (500 microliters), high-performance liquid chromatographic separation and direct spectrophotometric detection at 119 nm. Extraction can be checked by the use of an internal standard. The reproducibility, recovery and separation of fractions were satisfactory.

Bile Acids and Salts↗
PubMed1989

Crigler-Najjar type II disease inheritance: a family study.

The inheritance of Crigler-Najjar type II disease is still contested. Autosomal dominant transmission with incomplete penetrance and autosomal recessive transmission have been proposed. We had the opportunity to study the hepatic activity of bilirubin uridinediphosphate glucuronyltransferase in parents whose first child had been affected by Crigler-Najjar type II disease. The demonstration of reduced activity of glucuronidation in the liver of both parents suggests autosomal recessive inheritance. The second infant of this couple was affected by the same disease and was treated with success by phenobarbital.

Bilirubin↗
PubMed1989

Bile acid glycine and taurine conjugates in serum of patients with primary biliary cirrhosis: effect of ursodeoxycholic treatment.

We have applied a specific and accurate high pressure liquid chromatographic technique to determine fasting serum glycine and taurine conjugates of individual bile acids in patients with primary biliary cirrhosis before and during ursodeoxycholic acid therapy. The study was carried out in nine patients in whom the diagnosis of primary biliary cirrhosis was established according to accepted criteria. After one year of UDCA therapy liver function tests significantly improved. Total serum bile acid concentration did not change significantly (29.2 (31.5) v 28.3 (26.4) microM). Total UDCA (1.7 (2.2) v 13.3 (14.5) microM) and glyco UDCA (0.8 (1.6) v 10.9 (11.4 microM) but not tauro UDCA levels increased significantly (p less than 0.01); UDCA (7.7 (12.6) v 40.2 (12.7)%) became the major species of the circulating bile acids. Primary bile acids (23 (28.3) v 11.2 (10.5) and their glycoconjugates fell significantly (p less than 0.01). There were no significant changes in the concentrations of conjugates of the secondary bile acids (4.5 (3.8) v 3.9 (3.0]. Our study shows that oral administration of UDCA to patients with primary biliary cirrhosis induced marked changes in the circulating pool of endogenous bile acids together with improvement in liver function test values. The data also suggest that the beneficial effect of longterm administration of UDCA in these patients might be mediated through changes in the circulating primary bile acids and UDCA rather than through changes in the circulating secondary bile acids, deoxycholate and lithocholate.

Bile Acids and Salts↗
PubMed1987

Deficient induction of sulfobromophthalein conjugating activity by phenobarbital in hamster liver.

Administration of phenobarbital, a known inducer of glutathione S-transferase activity in rat liver, failed to stimulate sulfobromophthalein (BSP) conjugation by liver cytosol in hamsters. The latter displayed poor ability to conjugate this substrate, despite very high glutathione-conjugating activity with the broad-spectrum substrate 1-chloro-2,4-dinitrobenzene (CDNB). Of the six substrates tested, in this species, 1,2-epoxy-3-(4-nitrophenoxy)propane (ENPP) was the only one whose conjugation was greatly enhanced by phenobarbital (+172%). Nevertheless, hamsters proved as responsive to phenobarbital induction as rats, since it increased their relative liver weight and microsomal enzyme activity. The deficient induction of liver BSP-conjugating activity observed with phenobarbital is consistent with the finding that it did not affect the hepatic transport of this substrate in hamsters.

Animals↗
PubMed1984

Plasma prolidase activity: a possible index of collagen catabolism in chronic liver disease.

We describe here an easy method of determining prolidase (EC 3.4.13.9) in plasma after preincubation with Mn2+ for 24 h at 37 degrees C to maximize prolidase activity. The mean activity in 338 patients who were either in hospital or outpatients was 900 U/L +/- 520 (2 SD), unrelated to sex or age. In 25 of these 338 samples tested, prolidase activity was between 1500 and 2000 U/L. It exceeded 2000 U/L in eight, all of whom were patients with chronic liver disease. Plasma prolidase activity was normal in cytolytic syndromes such as liver or heart disease. Of the 27 patients with cirrhosis, only five exhibited prolidase activity greater than 2000 U/L. Plasma prolidase activity was uncorrelated with six biochemical indexes to liver function (the aminotransferases, alkaline phosphatase, glutamyltransferase, total bilirubin, and serum albumin) or with the degree of cirrhotic fibrosis. We believe that plasma prolidase activity may be high only in the early stage of fibrosis. This hypothesis would be consistent with the data on rat-liver collagenolytic activities during CCl4 administration. Monitoring of plasma prolidase activity might be useful in evaluating fibrotic processes in chronic liver disease in the human.

Adolescent↗
PubMedDate not supplied

[Enzyme calibrators: principle and practical use].

Results of catalytic activities of enzymes are highly dependent on the measurement procedures and on local conditions. Thus, only poorly marked improvement of interlaboratory comparability of results have been observed in clinical enzymology. To solve this problem, SFBC and IFCC have proposed to use "validated enzyme calibrators". Standardised operating procedures adapted to 37 C have been developed by IFCC for the most commonly used enzymes in clinical chemistry, and will be soon published. Reference materials which have been certified with these SOPs can be used as calibrators for a set of measurement methods which exhibit the same analytical specificity. Calibrators must be commutable, a property that must be checked experimentally. It is possible to produce stable and commutable materials for the calibration of a set of methods. Interest of this approach has been demonstrated for several enzymes. Results of two studies presented here show that the comparison of results to the upper limit of reference ranges does not improve the interlaboratory comparability of results in contrast to the calibration of different methods by a common calibrator which allowed to reach an interlaboratory CV close to 4% for ALT and gammaGT.

Calibration↗
PubMedDate not supplied

[Correction of bilirubin glucuronyl transferase in Gunn rats by gene transfer in the liver using retroviral vectors].

The in vivo procedure for retrovirus-mediated gene transfer into rat liver allows genetic modification of 1 to 5% hepatocytes and the expression of a foreign gene for more than one year. We have used the Gunn rat as a model of the human Crigler-Najjar type I syndrome to assess the pertinence of this approach for the treatment of severe liver genetic diseases. After transfer of the rat bilirubin uridin diphosphate-glucuronosyl transferase cDNA into hepatocytes, 15 Gunn rats were examined during several months and sacrificed. Bilirubin glucuronides were excreted in the bile of all recipients, and serum bilirubin levels were significantly reduced in the treated population. The decrease was more than 40% in 5 of the 15 rats. These date showed that long term expression of a therapeutic protein can be obtain after in vivo retrovirus-mediated gene transfer into the liver.

Animals↗
PubMedDate not supplied

[Role of biology in the follow up of viral hepatitis].

Biological tests are important for the diagnosis and the follow-up of viral chronic hepatitis. The viral hepatitis C is by far the most frequent. The etiologic diagnosis is based on serological or immunological tests which have good sensitivity and specificity, and may be completed by molecular biological methods. In contrast, the tests for the evaluation of the activity (necrosis and inflammation) and of the fibrosis are less informative than the histological study. The diagnosis and prognosis interpretation of the aminotransferases are well known, but other tests as alpha glutathione S-transferase or orosomucoid are also proposed for evaluation of the activity. Some parameters as PIIINP or hyaluronic acid may be useful in the diagnosis and follow-up of fibrogenesis, fibrosis and cirrhosis but some new molecules, as the metalloproteinases and their inhibitors, are presenting interesting future prospects. Biological tests also contribute to the diagnosis of an associated extra-hepatic pathology and of a possible hepatocellular carcinoma occurring on the cirrhotic liver.

Fibrosis↗