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Biomedical subjects

M Gautier

Publications and source records attributed to M Gautier.

At least 73 records · Page 4Linked to original sources
PubMed1986

The use of Ultroser G as a serum substitute in the culture of human skin fibroblasts.

Growth of human skin fibroblasts was dramatically enhanced when serum in the culture medium was replaced by Ultroser G. Compared to the same cells cultured in the presence of serum, alterations in glucose and lipid metabolism and an increase in the activity of prolidase (EC 3.4.13.9) and prolinase (EC 3.4.13.8) were also observed. Consequently, we advise extreme caution in the use of Ultroser G in metabolic studies, especially for periods of culture exceeding 10 days. However, Ultroser G can help to produce a large number of cells and so facilitate purification of the proteins produced during the stationary growth phase.

Ascorbic Acid↗
PubMed1985

Cell density affects prolidase and prolinase activity and intracellular amino acid levels in cultured human cells.

Prolidase (EC 3.4.13.9) and prolinase (EC 3.4.13.8) and intracellular amino acid levels in cultured human cells increased when cell density rose. Firstly, two normal fibroblast strains were continuously cultured for 21 days and these parameters were measured on days 3, 7, 10, 14, 17 and 21 after plating. Prolidase, prolinase and amino acid levels varied considerably depending on the duration of culture and growth rate. Secondly, we studied the action of different cadmium and cobalt concentrations on prolidase activity. These two effectors altered this enzyme activity, but secondarily to modifying cell density. Thirdly, prolidase activity was investigated in 8 control amniotic cell strains, with a view to prenatal diagnosis of inherited prolidase deficiency, and we noted the same cell density interference. Due to the large variations related to cell density, we recommend specifying the number of cells per unit surface, and avoiding the term 'cells at confluency' which is unduly vague.

Amino Acids↗
PubMed1984

Evidence that cycloleucine affects the high-affinity systems of amino acid uptake in cultured human fibroblasts.

The influence of cycloleucine on kinetic parameters of uptake of L-alanine, L-proline and L-leucine into cultured human fibroblasts was examined under initial-rate conditions with substrate concentrations of 0.05-10 mM and 5 mM-cycloleucine. Kinetic data obtained by computer analysis showed that, in the absence of cycloleucine, cell uptake was heterogeneous for each amino acid. L-Alanine and L-leucine entered by two transport systems with different affinities; L-proline was taken up by one saturable transport system plus a diffusion-like process. This heterogeneity disappeared in the presence of cycloleucine, since the high-affinity systems were no longer detectable. The remaining process had the same kinetic constants as the low-affinity system for alanine and leucine and a KD similar to the diffusion constant for proline. The influence of cycloleucine on the amino acid uptake was not specific either to the amino acid concerned or to a particular transport system, since the three neutral amino acid-transport systems, A, ASC and L, were involved in these experiments. This influence was shown to be unaffected by the absence of Na+ (for leucine uptake). ATP content of the cells was identical in the presence or in the absence of cycloleucine.

Adenosine Triphosphate↗
PubMed1984

Voluntary total fasting: a challenge for the medical community.

A movement opposing the nuclear arms race asked for medical surveillance of four people intending to go without food for an unlimited period. The course of fasting was uneventful until day 28-35, when weight loss reached 18%. In one subject fasting was ended on day 38 owing to development of Wernicke's encephalopathy; the others agreed to suspend their fast by day 40. The presence of physicians, offered under defined conditions, may have contributed to the timely cessation of this protest.

Adult↗
PubMed1984

Comparative use of fructose and glucose in human liver and fibroblastic cell cultures.

The effect of fructose as a substitute for glucose in cell culture media was investigated in human skin fibroblast and liver cell cultures. Cells were grown for between 2 and 10 days in identical flasks in four different media, containing 5.5 mmol X 1-1 and 27.5 mmol X 1-1 glucose and fructose, respectively. In the presence of fructose, cell growth was stimulated, but less in liver cells than fibroblasts. At Day 6, increases were observed in [3H]thymidine incorporation, protein levels, and amino acid consumption, and a reduction was noted in ATP levels. In media containing 5.5 mmol X 1-1 glucose or fructose, consumption of fructose was four times lower than that of glucose at Day 3 and did not rise until Day 6. In fructose media, the lactate production was very low (four to five times less than that of glucose) and the pH values were always higher. Some findings were different for the fibroblasts and liver cells, owing to the specific characteristics of these two cell types in culture; this applied especially to the effects of glucose and fructose concentrations of 27.5 mmol X 1-1. Several possible explanations for the stimulation of cell growth in fructose medium were discussed.

Adenosine Triphosphate↗
PubMed1984

Relationship between cell density and prolidase activity in human skin fibroblasts: effects of ascorbate and fructose.

To evaluate the influence of cell density on the activity of fibroblast prolidase (EC 3.4.13.9), we determined this activity in sparse and dense cultures. We also investigated, the effects of different concentrations of beta-D (-) fructose and L (+) ascorbate, which both increased cell density at confluency. For a fructose concentration of 25 mM, we observed that in the absence of glucose, intracellular total proteins increased 1.5-fold and prolidase specific activity, 1.8-fold. For ascorbate, a broad optimum concentration was found (range 0.01 - 0.50 mM). Addition to cultures of 0.1 mM ascorbate increased total proteins 1.4-fold, and doubled prolidase activity. This investigation was prompted by our previous results [J. Metab. Dis. 1983, 6, 27-31], confirmed here, and suggesting that increased prolidase activity at confluency was due to a rise in cell density.

Ascorbic Acid↗
PubMed1984

Histological liver evaluation 5 years after surgery for extrahepatic biliary atresia: a study of 20 cases.

Clinical, biological, and histological data are described in 20 patients at least 5 years after surgery for extrahepatic biliary atresia. Seventeen had an " uncorrectable " type and underwent hepatoportoenterostomy or hepatoportocholecystostomy , 3 patients had a "correctable" type and underwent cystojejunostomy . Clearing of jaundice was observed in all patients. Portal hypertension developed in 16 out of the 20. Liver specimens were obtained by surgical biopsy in all patients. Definite biliary cirrhosis was seen in all but two. Particular patterns were observed in some cases: biliary structures without bile stasis were absent in 8, while 4 displayed marked cell infiltration in portal areas, and 7 had distended vascular channels. The appearance of liver cells was always normal. No relationship could be clearly established between the degree of fibrosis and the earlier presence of cholangitis.

Bile Ducts↗
PubMed1984

Measurement of changes in amino acids related to total collagen in fibrotic human liver.

In the liver, total collagen accumulation during the fibrotic or cirrhotic process was measured using a methodology based on the determination of collagen amino acids in liver biopsies from adults with alcoholic liver diseases or children with biliary atresia. The results obtained with this methodology were compared to histopathological findings. Thus, it was shown that generally the severity of hepatic injury was dependent on collagen accumulation. In biliary atresia, collagen accumulation increased with the children's age despite reconstructive surgery and restoration of biliary flow.

Adult↗
PubMed1983

In-vitro responses to ascorbate and manganese in fibroblasts from a patient with prolidase deficiency and iminodipeptiduria: cell growth, prolidase activity and collagen metabolism.

After successful ascorbate and manganese treatment of a female patient with prolidase deficiency and iminodipeptiduria, we attempted to explain the mechanism of action of these drugs in vitro, using them preferentially on skin fibroblasts. Since in vivo, ascorbate and manganese seemed to be responsible for both biochemical and clinical improvement, they were also expected to activate prolidase activity in vitro. Cell growth and prolidase activity were accordingly observed in fibroblast cultures supplemented with these compounds. It seemed that only ascorbate accounted for the successful in vivo response. To understand the mechanism involved, we studied collagen metabolism and found a decreased proline pool, a massive increase of rapidly degraded collagen and moderate enhancement of type III collagen and type I trimer in the patient's fibroblasts. We believe that ascorbate allowed the prolidase-deficient cells to maintain a normal collagen pool by increasing collagen synthesis. Both the massive increase in cell growth in response to ascorbate and the bad response as regards the quality of the collagen produced confirm the secondary nature of this mechanism. However, the relationship between accelerated collagen catabolism and prolidase deficiency remains unclear.

Adult↗
PubMed1983

Comparative effects of glucose and fructose on growth and morphological aspects of cultured skin fibroblasts.

The growth rate of human skin fibroblasts was evaluated when glucose was replaced by fructose in the culture medium. Four mediums containing respectively 5.5 mmol/l glucose (G1), 27.5 mmol/l glucose (G5), 5.5 mmol/l fructose (F1), and 27.5 mmol/fructose (F5) were used. Skin fibroblasts from fourteen subjects were continuously cultured for 20 days and the number of cells was counted at days 1, 3, 7, 10, 15 and 20 after plating. The morphological patterns were observed and compared, the pH values of the medium were calculated, as were hexose consumption and lactate production. The results established clear differences in cell growth, pH and morphology: up to day 7, the growth rate was lower in fructose than in glucose medium, and the pH values were higher. In addition, marked steatosis appeared, with increased pyruvate dehydrogenase (PDH) activity. After day 10, the mean values gave a significant increase in the number of cells grown in fructose mediums, even if variations occurred between different cell strains. This increase was accompanied by loss of density-dependent growth inhibition and a reduction in the quantity and size of the vacuoles caused by steatosis. These findings were also established for other cell types, like aponeurosis fibroblasts. In addition, the longevity of the strains increased. These observations indicate that intermediary metabolism is considerably influenced by the carbohydrate present in the cell culture medium and that there are also repercussions on the growth rate. Under our experimental conditions, metabolism pathways seemed to differ on day 7 and on day 20. The various metabolic events suggested by the differences in the pH values are now being studied in our laboratory.

Cell Division↗
PubMed1983

Extent of 14C incorporation into cholesterol of infant skin fibroblasts incubated with carboxyl-labeled oleic, -linoleic or -arachidonic acid.

In order to determine the incorporation of C1-14C derived from mono- and poly-unsaturated fatty acids into cholesterol of human cells cultured in exponential phase, infant skin fibroblasts (SF) were used at the 5th passage. On Day 6, the SF were preincubated 36 h in a medium containing 5 per cent lipoprotein-deficient serum, and thereafter [1-14C] oleic, -linoleic or -arachidonic acid-without (OL1, LI1 and AR1 group SF), or with the addition of 0.25 mM cold fatty acids (OL2), LI2 and AR2 group SF). Cholesterol specific radioactivity (SRA) peaked 1 h after, and leveled off afterwards in the OL1, LI1 and AR1 groups. Cholesterol-SRA was relatively low in the other groups, but increased progressively, giving a biphasic response: C1-14C derived from from linoleic and arachidonic acids was actively incorporated into cholesterol during the first hours, as compared to C1-14C derived from oleic acid, but stabilized between 6 and 12 h for the LI2 and AR2 group SF incubation. This result appears to be due to the stimulation of pyruvate decarboxylation, observed elsewhere, and consequently to the dilution of the radioactive units in a large pool of non-labeled acetyl-CoA units derived from glucose, when these SF were incubated with 0.25 mM polyunsaturated fatty acids.

Arachidonic Acid↗
PubMed1981

Effects of Pexid on liver cell cultures. Ultrastructural and histoenzymological studies.

The effects of different doses of Pexid on cultured liver cells have been studied by ultrastructural and histoenzymological techniques. Two types of abnormal lysosomal inclusions were seen: clear matrix inclusions with either homogeneous or tiny lamellar structures, and dark matrix inclusions with clear vacuoles and either random or myelin-like lamellar structures. These patterns correspond to storage of triglycerides, phospholipids and gangliosides, either singly or together.

Cells, Cultured↗
PubMed1981

D-glucose uptake in human liver cell cultures.

The kinetics parameters for D-glucose uptake were studied in human liver cell cultures under strictly defined experimental conditions. Using a wide concentration range (0.005 to 30 mmol/l), the kinetic data obtained suggested strongly that D-glucose in human liver cell cultures can be transported by two separate systems. For the high-affinity system, the apparent Km was 0.645 +/- 0.21 mmol/l and the Vmax, 12.49 +/- 3.74 nmol/mg protein per min. For the low-affinity system, the apparent Km was 6.91 +/- 0.58 mmol/l and the Vmax, 79.90 +/- 5.27 nmol/mg protein per min. At a concentration of 2.1 x 10(-7) mol/l, cytochalasin B preferentially inhibited the high-affinity D-glucose site or transport system. The time course of D-glucose uptake, studied in two cell lines from patients with hereditary fructose intolerance, was significantly higher than for the control lines.

Biological Transport↗
PubMed1981

Somatomedin activity measured as sulphation factor in culture media from normal human liver and connective tissues explants. Effects of human growth hormone.

Normal human explants from liver and from connective tissues (aponeurosis or skin) incubated in vitro released sulphation activity measurable in chick embryo cartilage. Addition of human Growth Hormone (hGH) at physiological levels (10 ng/ml) increased the sulphation activity after 6 hours incubation time. Higher doses failed to increase the sulphation activity produced by connective tissues and decreased the sulphation activity produced by the liver.

Animals↗
PubMed1981

Extrahepatic biliary atresia. Morphological study of 98 biliary remnants.

Histologic examination was performed on 98 biliary remnants. Classification into three types was made according to the presence of epithelial structure; biliary and glandular formations had to be separated. Atretic lesions were predominantly observed at the pars inferior of the remnants. These histological findings agree with the theory of a dynamic ascending process that leads to progressive, complete destruction of the biliary and glandular structure, although main ducts may remain preserved by the vicinity of the porta hepatis. Classic clinical data suggest that the damage is initiated in utero. The lesions certainly progress after birth; in some cases the fibrotic process of the remnant may have already reached completion at birth, whereas in some others it may become clinically evident after birth.

Bile↗
PubMed1980

Some metabolic differences between human skin and aponeurosis fibroblasts in culture.

Two types of human fibroblast strains were studied in culture. One was derived from abdomen skin and the other from abdominal muscle aponeurosis. Tissue-specific differences were found between these two cell strains. Skin fibroblasts had faster doubling time, smaller cell volume, and lower glucose consumption when compared to aponeurosis fibroblasts. Furthermore, extracellular amino acid variations showed some specific differences, in particular a lack of serine consumption in skin fibroblasts.

Amino Acids↗