Plasma zinc and copper in Paris area preschool children with growth impairment.

Plasma zinc, copper, and parameters of growth were measured in a group of 116 French preschool children, 2-5 yr-old from low-income households. Participants were selected on the basis of Z-scores of weight for height (WHZ) and height for age (HAZ). Zinc and copper concentrations of children with growth impairment (GI), defined by a WHZ and/or HAZ < -1 Z-score, were compared to those of age, sex, and ethnic origin matched controls (WHZ and HAZ > -1 Z-score). Mean (+/- SD) plasma zinc concentration was 12.58 +/- 1.84 mumol/L in the GI group, and 13.27 +/- 1.98 mumol/L in the controls. The difference of the means of paired samples was 0.69 +/- 2.34, and by paired t-test the significance reached p = 0.028. This effect was primarily a result of the weight retarded group (WHZ < -1 Z-score, p < 0.009) and to the girls (p < 0.05). There were no significant differences in plasma copper concentrations between groups. These results suggest the presence of marginal zinc deficiency in French preschool children with low weight for height Z-scores.

Decreased serum levels of nutritional biochemical indices in healthy children with marginally delayed physical growth.

Biochemical markers of nutritional status (albumin, transthyretin, insulin-like growth factor-I and zinc) were measured in slowly growing two- to five-year-old, low-income Parisian children whose weight-for-height or height-for-age z scores (WHZ or HAZ) were between -1 and -2 SD of the NCHS median. The results were compared to controls who were matched for age, sex, and ethnic origin with WHZ and HAZ between -1 and +2 SD. Mean serum levels of transthyretin, albumin and insulin-like growth factor-I and mean plasma zinc concentrations were significantly lower in the growth-impaired children than in the controls (p = 0.002, p = 0.006, p = 0.015, and p = 0.035, respectively). While the height-retarded children had low mean serum insulin-like growth factor-I values, the weight-retarded subjects had decreased levels of albumin, transthyretin and zinc when compared to controls. Lower mean levels of nutritional markers in healthy, slowly growing children suggest that inadequate dietary intakes of zinc, protein and/or energy may result in marginal delays in weight and height gains.

Selenium status of healthy immigrant Parisian preschool children.

Plasma selenium (Se) concentration and erythrocyte glutathione peroxidase activity (GPx) were assessed in a population of healthy preschool children two to five years old, residing in the city of Paris. In the 118 subjects, mean (+/- SD) plasma Se concentration was 62.10 +/- 13.96 micrograms/L, and mean GPx activity was 23.58 +/- 8.52 U/g Hb. Mean plasma Se of male children was significantly (p = 0.001) higher (12%) than levels of girls. Plasma selenium levels were not correlated with erythrocyte GPx activity. Children from Mediterranean origin had a slightly lower erythrocyte GPx activity (p < 0.05) than children from other regions. Mean plasma Se concentration of this group corresponded to the lower limit of intervals, which characterizes geographical regions of intermediate selenium concentrations.

Usefulness of red cell distribution width in association with biological parameters in an epidemiological survey of iron deficiency in children.

The diagnostic usefulness of red cell distribution width (RDW) in association with usual biochemical and haematological parameters in detection of iron deficiency has been studied in a representative sample population of 384 children aged six months to six years in Reunion. Traditional parameters measured included serum ferritin (Fri), total iron binding capacity (TIBC), serum iron (SI), transferrin saturation (TSat), free erythrocyte protoporphyrin (FEP), mean corpuscular haemoglobin concentration (MCHC), mean corpuscular haemoglobin (MCH), mean corpuscular volume (MCV) and haemoglobin concentration (Hb). RDW is an index of the variation in red cell size (anisocytosis). This recently derived parameter is measured by some models of electronic cell counter. It is not usually used in epidemiological investigations. Of the children studied, 13.6% had Hb less than 11 g/dl. The Pearson correlation coefficients between circulating iron parameters (SI, TSat, TIBC) or iron storage parameters (Fri) and RDW, MCV, MCH and FEP were greater than with Hb. The best correlations were observed for RDW, MCV and MCH with all other parameters. In this study, the upper limit value of RDW was defined as 18% using a Technicon model H-6000 counter. Other iron deficiency criteria were also defined and found to be in agreement with the international reference values for children aged six months to six years; MCV less than 70 fl, MCH less than 22 pg, MCHC less than 32%, FEP greater than 35 micrograms/dl whole blood, SI less than 6 mumols/l, TIBC greater than 85 mumols/l, TSat less than 10% and Fri less than 12 micrograms/l. The combination of sensitivity and specificity was best for RDW and worst for MCHC.(ABSTRACT TRUNCATED AT 250 WORDS)

[Changes in hepatic enzyme activities of drug metabolism in rats exposed to normobaric oxygen]. / Modifications des activités enzymatiques hépatiques du métabolisme des médicaments chez le rat exposé à l'oxygène normobare.

Exposure of adult rats to 1 ATA O2 during 55 hrs. decreased cytochrome P-450 in the homogenate supernatant of livers. Hepatic microsomal epoxide hydrolase and P-nitrophenol UDP-glucuronosyltransferase activities were also decreased. Histological and ultrastructural liver studies showed tissular and cellular modifications suggestive of hepatocyte hypoxia.

Study of biochemical behavior of some exported and nonexported hepatic proteins during an acute inflammatory reaction in the rat.

Haptoglobin, albumin, glucose-6-phosphatase, p-nitrophenol uridine diphosphate (UDP)-glucuronosyltransferase and cytochrome P-450 were measured in liver microsomes from normal rats and from rats undergoing an acute inflammatory reaction (AIR) induced either by subcutaneous administration of turpentine or by intrapleural injection of calcium pyrophosphate. 24 h after the beginning of the AIR induced by subcutaneous administration of turpentine, haptoglobin and albumin, two exported proteins, had risen to a peak (+313%), and dropped considerably (-52%) whereas nonexported protein levels did not change except for cytochrome P-450, which diminished (-38%). In the same way, intrapleural injection of calcium pyrophosphate was followed after 24 h by significant but smaller variations in haptoglobin (+60%) and cytochrome P-450 (-20%) concentrations. Albumin levels, glucose-6-phosphatase and p-nitrophenol UDP-glucuronosyltransferase activities were unchanged in this experimental model. The drop in cytochrome P-450 under all these conditions and also the diminution of albumin in the first model suggest that all the proteins produced by liver cells might not be synthesized in equal amounts. The decrease in cytochrome P-450 could interfere in hepatic drug metabolism during an AIR.

Relationship between microtubules and Golgi apparatus in hepatocytes: a quantitative study during experimental nephrosis.

In many cell types, microtubules are preferentially associated with the Golgi apparatus. However, the existence of a functional link between these two organelles is still hypothetical. To gain insight into this question, the relationships between microtubules and the Golgi apparatus were studied in rat hepatocytes during experimental nephrosis induced by the aminonucleoside of puromycin. This condition is known to cause prolonged stimulation of plasma protein production by the hepatocytes. Rats were studied 2, 4, 5, 10 and 20 days after aminonucleoside injection. The amount of albumin was measured in serum and hepatic microsomes by laser immunonephelometry. The volume densities of microtubules around the Golgi apparatus and in the remaining cytoplasm were measured by ultrastructural morphometry. Changes of the Golgi apparatus were analysed by measuring the volume density of the whole organelle and the respective proportion of saccules and vesicles. Proteinuria began 5 days after aminonucleoside injection and was accompanied by a decrease in serum albumin and a rise in microsomal albumin. These changes were still more striking after 10 days, but protein and albumin levels were almost back to normal after 20 days. Concomitantly, the volume density of the microtubules increased significantly around the Golgi apparatus (32% after 10 days), and not in the remaining cytoplasm. The Golgi apparatus was enlarged (80% after 10 days) with a higher ratio of secretory vesicle to saccule volume densities. These results show that additional microtubules are present around the Golgi apparatus during the enhanced production of plasma proteins which occurs in nephrosis. They suggest that in hepatocytes, microtubules play a part in the Golgi apparatus function of plasma protein processing.

Induction of drug metabolizing enzymes in the liver of diabetic mice.

The effects of two classical inducers, phenobarbital and 3-methylcholanthrene, have been tested on some liver microsomal drug-metabolizing enzymes (monooxygenases and phase II enzymes) and on benzo(a)pyrene metabolism in genetically (ob/ob) and chemically (streptozotocin) diabetic mice. 1) In ob/ob mice, the basal activities and the inducibility of phase I and phase II enzymes, as well as the electrophoretic pattern of microsomal proteins, were not notably different from those of similarly treated lean mice. 2) A possibly common form of cytochrome P 450 present both in microsomes from steptozotocin-diabetic non-induced mice and in those from phenobarbital-treated non-diabetic mice could explain the increased "phenobarbital-like" enzyme activities in chemically diabetic animals. 3) The increase of monooxygenase activities produced by streptozotocin treatment is partially depressed by 3-methylcholanthrene, probably as a result of the dilution of "phenobarbital-like" cytochrome P 450 forms by 3-methylcholanthrene-induced cytochrome P 448. 4) The increased formation of the most carcinogenic metabolites of benzo(a)pyrene, and the slight decrease of phase II conjugation enzyme activities, may add their deleterious effects in 3-methylcholanthrene-induced streptozotocin-diabetic animals.

Effect of fasting on organic anion uptake by isolated rat liver cells.

In order to determine if the delayed clearance of organic anions observed in vivo after fasting can be related to an alteration of cell membrane carriers, kinetics of sulfobromophthalein (BSP) uptake were determined in isolated rat liver cells obtained from 48-hr starved rats. Surprisingly, in fasted rats the existence of two carriers can be directly revealed by classical kinetic plots. The high-affinity component, inhibited by Na+-taurocholate, has a Km of 0.5 +/- 0.2 microM and a Vmax of 0.2 +/- 0.1 nmole per min per 10(6) cells; the low-affinity component, which is not sensitive to Na+-taurocholate, has a Km of 21.2 +/- 3.2 microM and a Vmax of 4.8 +/- 0.9 nmoles per min per 10(6) cells. Comparison with control cells shows that fasting does not modify the total capacity of the liver cell membrane carriers to take up BSP. However, alterations in the kinetic parameters of the two uptake components were observed: a 53% decrease in the affinity of the low-affinity component and a 50% reduction in the capacity of the high-affinity uptake. These alterations, together with the observed decrease in hepatic blood flow and/or the increase in BSP efflux from the hepatocytes, could be involved in the delayed clearance of BSP and other anionic compounds occurring in vivo after fasting.

UDP-glucuronosyltransferase, epoxide hydrolase and glutathione S-transferase activities in the liver of diabetic mice.

The activities of UDPglucuronosyltransferase, microsomal epoxide hydrolase and cytosolic glutathione S-transferase were measured in the liver of spontaneously (db/db and ob/ob) or streptozotocin-induced diabetic mice. An important (2-3-fold) increase of most phase II activities was observed in streptozotocin-treated animals, whereas slighter changes were detected in spontaneously diabetic animals. The latter also exhibited physico-chemical modifications of the liver microsomal membranes, as shown by the temperature-induced variations of epoxide hydrolase activity.

Characterization of microsomal bilirubin and p-nitrophenol uridine diphosphate glucuronosyltransferase activities in human liver: a comparison with rat liver.

The bilirubin and p-nitrophenol uridine diphosphate glucuronosyltransferase (UDP-GT) activities have been characterized from human liver microsomes and compared to those from rat liver. This study was performed on large samples of human liver obtained from 20 organ donors. The kinetic constants as well as sensitivities to digitonin, temperature, pH and diethylnitrosamine were determined. Our results suggest that UDP-GT activities have characteristics different in human and rat liver microsomal membranes. Moreover, differences in digitonin-induced activation, in thermodenaturation and in the response to diethyl-nitrosamine were found between bilirubin and p-nitrophenol UDP-GT activities. This supports the hypothesis of the probable heterogeneity of UDP-GT.

Comparison of the effects of phenobarbital and its hydroxylated metabolites on drug-metabolizing enzymes during ontogenesis.

Twenty-two-day-old fetal and five-day-old newborn rats were pretreated with phenobarbital and its hydroxylated metabolites. Drug-metabolizing enzymes (cytochrome P450, epoxide hydrolase, UDP-glucuronosyltransferase, and glutathione-S-transferase) and microsomal ribonuclease were not modified in fetuses treated with 80 or 400 mg . kg-1 of p-hydroxyphenobarbital, in spite of its accumulation in fetal liver. At fetal age, phenobarbital was a poor inducer of drug-metabolizing enzymes. In five-day-old newborns, p-hydroxyphenobarbital provoked a proliferation of endoplasmic reticulum without enzyme induction, whereas phenobarbital induced some drug-metabolizing enzymes. Thus, the effects of p-hydroxyphenobarbital and phenobarbital are retained in five-day-old rats, but undetectable in the fetuses.

Possible role of a defect in hepatic bilirubin glucuronidation in the initiation of cholesterol gallstones.

Abnormally low activity of hepatic bilirubin UDP-glucuronosyltransferase was found in 25% of 81 unselected patients with gallstones, as compared with only 3% in 35 controls. At the time of cholecystectomy, the stones were taken for analysis in 48 of 81 patients, and a bile sample was obtained in 42 of them. Among the stones, 75% were cholesterol stones, 15% pigment stones, and 10% 'intermediate' stones. Low hepatic conjugating activity was not preferentially associated with a given type of stone. No relation was found between the enzymic deficiency and the biliary cholesterol saturation index. A high proportion of biliary bilirubin monoglucuronide (over 40%) was found in four of seven patients with low transferase activity, as was earlier demonstrated in patients with overt Gilbert's syndrome. Raised biliary bilirubin monoglucuronide was also found in three patients, out of 46, who had normal transferase but raised biliary beta-glucuronidase activity. There was no evidence that deficient bilirubin conjugation could be a consequence of gallstones: the activity of another hepatic microsomal enzyme, glucose 6-phosphatase, taken as a reference, was measured in 12 patients and was always normal. Taking into account the very high frequency of a bilirubin centre in the cholesterol stones (87% of the cases in the present series), it is suggested that the increased proportion in poorly soluble biliary bilirubin monoglucuronide, which was associated with defective conjugation, could act as a trigger for gallstone initiation, regardless of the final composition of the stone.

RMI 12330 A, an inhibitor of adenylate cyclase in rat liver.

RMI 12330 A, (N,-(cis-2-phenylcyclopentyl) azacyclotridecan-2-imine hydrochloride), has been reported to inhibit choleratoxin-induced intestinal hypersecretion, presumably via an inhibition of mucosal adenylate cyclase (ATP:pyrophosphate-lyase (cyclizing), EC 4.6.1.1). We report here that the adenylate cyclase activity of a rat liver plasma membrane preparation was inhibited by concentrations of RMI 12330 A ranging from 10 muM to 5mM. Similar effects were observed when the adenylate cyclase preparation was assayed in the presence of 10 mM NaF, 0.1 muM glucagon or 1 muM (--)-epinephrine plus 10 muM GTP. The effect of RMI 12330 A was not due to the inhibition of the regenerating system present in the incubation medium, since the effect was preserved in its absence. The inhibition brought about by RMI 12330 A was due to a decrease in the maximal velocity of the reaction; the affinity of the enzyme for the substrate remained unmodified. The inhibition was immediate and irreversible, even after several washes of the membranes previously preincubated with the drug. Complete inhibition of cyclase was obtained at a concentration of 370 nmol of RMI 12330 A per mg of membrane protein. The drug acted with a similar dose-response curve upon intact as well as detergent-dispersed cyclase preparations.

Biliary transport of cholephilic dyes: evidence for two different pathways.

The hepatobiliary transport of three structurally related phthaleins was compared in the rat, and found to differ to a large extent in three experimental conditions: 1) after a 72-h fast; 2) after a 4-day phenobarbital treatment; and 3) during infusion of bile salts: sodium dehydrocholate or taurocholate. In the fasting group, bile flow and bile salt excretion (on a whole liver basis) decreased by 49 and 41%, respectively; bromsulphthalein sodium (BSP) and dibromsulphthalein sodium (DBSP) transport maximum (Tm) were reduced by 59 and 50%; however, rose bengal (RB) Tm remained normal. Phenobarbital pretreatment yielded a 44 and 29% increase in BSP and DBSP Tm, respectively, whereas RB Tm remained unchanged. Dehydrocholate infusion caused a 27 and 49% increase in BSP and DBSP Tm, whereas RB Tm increased by 12%. On the contrary, equimolar taurocholate infusion yielded a more important increase in RB Tm (56%) than in BSP and DBSP (31 and 22% respectively). It is suggested that RB does not share the same liver-to-bile excretory pathway as that of the former molecules. Our results emphasize the difficulties in predicting the biliary excretion of foreign compounds, even when their structure is closely similar.