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Biomedical subjects

P Fournier

Publications and source records attributed to P Fournier.

At least 145 records · Page 8Linked to original sources
PubMed1982

[An experimental study of bioglass implants in bone (author's transl)].

The tolerance and response of bone to bioglass have been studied using implants of various chemical constitution in animals. Glass discs were inserted between the inner and outer tables of the skull in 32 rabbits and small glass stick were implanted in the medullary cavity of long bones in 6 dogs. The results were analysed between 6 and 18 months later. High resolution radiographs and histopathological examination were performed. Some glass behaves like an inert material but other specimens are biodegradable and induce a satisfactory bone response in adjacent bone. Any new bone formation does not follow the classical stages of connective tissue, cartilage and woven bone. Bioglass is more suitable for bone than many other materials now in use and further applications in orthopaedic surgery may be considered.

Animals↗
PubMed1980

Notion of time factor in calcium absorption. Influence of sex, intestinal site and L-xylose in the mature rat.

The unidirectional influx of Ca (measured by in vitro methods) was similar along the intestine of the adult rat, from Treitz ligament to ileo-daecal valve. In in vivo ligated loop experiments, the rate of Ca absorption was similar during 30 min irrespective of site, sex and the presence of L-xylose in the Ca solution. On the contrary, these factors modified the quantity of Ca absorbed. After 30 min, absorption stopped in the male ileum whereas it continued (1) in the male jejunum; (2) in the ileum of the female, and (3) in the male ileum in the presence of xylose (absorption being proportional to xylose concentration). Thus, in the adult rat, the duration rather than the rate is the decisive factor in Ca uptake.

Animals↗
PubMed1980

Epidurography with metrizamide in Rhesus monkeys.

Epidurography with metrizamide was performed on 9 Rhesus monkeys; physiologic saline was substituted for metrizamide in 3 control monkeys. Metrizamide successfully outlined the epidural space without causing any adverse clinical effects or direct tissue injury.

Animals↗
PubMed1980

[Action of soluble carbohydrates from avocado (Persea gratissima Gaertner) fruit on utilization of calcium in the rat].

Ethanolic extract containing soluble sugars was prepared from avocados (variety americana) coming from Madagascar. In this extract, thin layer and paper chromatography showed the presence of a ketoheptose, the mannoheptulose, in amount of 0.1 g/ml extract or 1.1 g/100 g fresh pulp. Physiological experiments were performed with avocado extract and comparatively with a sample of commercial mannoheptulose. Six-month-old rats were given by stomach tube 10 mM CaCl2 solution (+ 45Ca) containing a carbohydrate. Depending on the group, the carbohydrate was 20 and 100 mM glucose (control), D-mannoheptulose 200, 100, 50 and 25 mM, avocado extract concentrated or diluted 1/2, 1/4, 1/8, 1/16. Blood samples were taken at different times after the administration and plasma radioactivity was measured. Rats were sacrificed at 24 hours; femur and axis radioactivity was used as a measure of calcium absorption. Both mannoheptulose and avocado extract were potent on calcium absorption. This absorption increased progressively with sugar concentration, in mannoheptulose and avocado groups. The interpretation of these results was discussed and also their application to the Nutrition in tropical and subtropical countries.

Absorption↗
PubMed1980

[Relations between the phosphorylation of aminated molecules and their action on the absorption of calcium].

Various amino acids and guanidines (L-lysine, L-aspartic and L-glutamic acids, creatine, taurocyamine and glycocyamine), studied in ileal ligated loops, increased intestinal calcium absorption in the rat. L-arginine was effective per os. Since these compounds are highly phosphorylable, a phosphorylation mechanism may be involved in the stimulation of calcium absorption. The phosphorylated derivative of creatine was detected in the ileal mucosa of rats receiving creatine in the ileal ligated loop. Modified amino acids, such as 5-methyl-L-glutamate, asparagine or glutamine, whose phosphorylable function was masked by a methyl or an amide radical, were not effective in enhancing calcium absorption. Assays in vitro showed that an ileal mucosa extract phosphorylated arginine, lysine, glycocyamine and taurocyamine in the presence of ATP, acting as a phosphate donor.

Adenosine Triphosphate↗
PubMed1980

[Effects of soluble carbohydrates from several tropical foods (cassava, peanuts, coconut and papaya) on calcium utilization in the rat].

Ethanolic extracts containing soluble sugars were prepared from four foods : cassava, peanut, coconut and papaye. Six-month-old rats were given by stomach tube 10 mM CaCl2 solution (+ 45Ca) containing a carbohydrate. Depending on the group, the carbohydrate was glucose or melibiose or raffinose at 200 mM concentration, or one ethanolic extract. Blood samples were taken at different times after the administration and plasma radioactivity was measured. Rats were sacrificed at 24 hours; femur radioactivity was used as a measure of calcium absorption. Extracts of cassava, peanut, and papaye were the more patent in promoting calcium absorption. Extracts of coconut were less effective. This physiological activity of the extracts was correlated with the nature of sugars, identified by paper chromatography. Cassava contained raffinose, peanut included fructose, raffinose and stachyose. Fructose was abundant in papaye but in little quantity in coconut. The present experiments or earlier works had showed that these sugars enhanced calcium utilization.

Animals↗
PubMed1979

[Expression of a bacterial gene, cloned in the yeast, Saccharomyces cerevisiae].

Vectors allowing cloning of foreign D.N.A. in the yeast Saccharomyces cerevisiae have been recently described. We have introduced in this yeast the lac Z gene of the bacteria Escherichia coli. An active beta-galactosidase, which is absent in the recipient strain, has been detected in transformed yeast. We thus conclude that the bacterial lac Z gene is expressed in yeast. We further showed that the enzyme found in the transformed yeast is identical to the bacterial enzyme with respect to size and immunological criteria.

Cloning, Molecular↗
PubMed1979

[Effect of creatine and other phosphorylable amino compounds on the ileal absorption of Ca-45 in the rat].

Some carbohydrates which increase calcium absorption were phosphate acceptors. When administrated to adult Rat in ileal ligated loop, phosphorylable amino compounds such as creatine, L-aspartic and L-glutamic acids also increased calcium absorption; other effective compounds such as D- and L-lysine and D-alanine might be involved in reactions of phorphorylation. L-alanine, L- and D-valine and asparagine were ineffective in enhancing calcium absorption and were not phosphorylable. Injection of creatine into ileal loop induced the formation of its phosphorylated derivative. Absorption of the amino compound was not correlated with the fact that they were effective on calcium absorption.

Amino Acids↗
PubMed1979

High frequency of yeast transformation by plasmids carrying part or entire 2-micron yeast plasmid.

By using two chimeric plasmids containing yeast ura3 gene and 2-micron yeast DNA linked to the bacterial plasmid pCR1, yeast transformation of a high frequency has been achieved. The first plasmid is such that the 2-micron DNA part, in which the ura3 gene is incorporated, can be removed in one step and thus the 2-micron-ura3 sequence can be considered as a "transposable" block. In contrast, the second one bears the entire 2-micron plasmid and the ura3 gene is inserted in the bacterial plasmid part. As shown through hybridization experiments and genetic studies, the ura3 gene was maintained as a cytoplasmic element. Plasmids recovered from the yeast transformants were used to transform Escherichia coli. Their analysis by EcoRI showed that in many cases the vector had recombined with the endogenous 2-micron DNA of the recipient strain. The specific activity of orotidine 5'-monophosphate decarboxylase (coded by ura3) in yeast transformants was 10- to 30-fold higher than in the wild type.

Chimera↗
PubMed1979

Effects of sitting up on pulmonary blood pressure, flow, and volume in man.

Pulmonary vascular pressure, blood flow, and blood volume were measured in the supine and sitting positions in eight subjects with localized lung carcinoma associated with moderate airway obstruction. Supine cardiac output, pulmonary wedge (Ppw) and artery (Ppa) pressure, and pulmonary vascular resistance (PVR) were normal. Circulatory changes in sitting position were also normal: heart rate increased 13 +/- 9% (mean +/- SD); stroke volume fell 21 +/- 15%; cardiac output fell 13 +/- 19%; and arteriovenous O2 difference increased 37 +/- 21%. Neither the difference between mean Ppa and mean Ppw nor the rise of PVR from 92 +/- 25 to 122 +/- 49 dyn.s.cm-5 in sitting position were significant. Pulmonary blood volume (PBV) as measured by a dye-bolus-injection technique fell from 517 +/- 122 ml supine to 360 +/- 43 ml sitting (P less than 0.01). This decrease is best explained by closure of alveolar vessels in the upper part of the lung and by the concomitant cessation of flow in corresponding extra-alveolar vessels, which would prevent distribution of dye in the region. Circumstantial evidence suggests the latter vessels remain open under the large expanding stresses that prevail in the upper lung.

Adult↗
PubMed1978

The relations between intestinal alkaline phosphatase and carbohydrates with regard to calcium absorption.

The effect of carbohydrates on calcium absorption were studied in situ following the injection of a solution containing CaCl2 (+45Ca) into the ileal loop. The increase in Ca absorption was proportional to the concentration of carbohydrates injected and could be attributed to a progressive increase in the duration of absorption. In the ileal loop, sorbitol was much more effective than L-arabinose at equal concentrations in activating absorption. Such differences in the action of these carbohydrates were also observed in vitro with alkaline phosphatase extracted from the ileum. The transphosphorylating effect of the enzyme was much more pronounced in the case of sorbitol. Since the carbohydrate is a phosphate acceptor, it might influence the duration of absorption by reducing the inhibition exerted by phosphate upon a transfer mechanism which involves phosphatase, another possibility is that carbohydrate could postpone calcium insolubility through the formation of a phosphocarbohydrate complex.

Alkaline Phosphatase↗
PubMed1978

[Inhibition of calcium absorption and conditions of its prolongation in the presence of carbohydrate].

Experiments were performed on adult rats. In situ ligatured ileal loops were injected with a solution 10 mM CaCl2 containing 45Ca either with or without L-xylose in concentrations of 25, 50 or 100 mM L-xylose. The rats were sacrified at either 0.5, 1.0, 1.5 or 2.0 hours after injection; the entire loop including the wall and content was removed. After ashing, the radioactivity of the loop was measured and the absorption coefficient of 45Ca was calculated. After half an hour, the absorption coefficient of the four solutions had about the same value. At this time, the 45Ca absorption was completed with the solution containing only calcium. With the solution containing pentose, the 45Ca absorption continued for a longer period of time. The maximal values of absorption coefficient were obtained after one hour with 25 and 50 mM L-xylose and after one and a half hour with 100 mM L-xylose; similarly, the maximal values increased in proportion to the concentration of pentose in the solution. The contents of the loops were fractionated successively by centrifugation, ultracentrifugation and two membrane ultrafiltration. No differences were observed between the repartition of 40Ca or 45Ca, either with or without 50 mM L-xylose. The stop or the lengthening of the absorption could be attributed to a possible influence of carbohydrate upon the mechanism of calcium transfer. This question is discussed from the point of relationship between the carbohydrate and the intestinal alkaline phosphatase.

Absorption↗
PubMed1977

Recombination after protoplast fusion in the yeast Candida tropicalis.

Candida tropicalis protoplasts obtained by snail enzyme treatment were induced to fuse by the use of polyethylene-glycol. Heterokaryons formed by two auxotrophic strains were selected by complementation on minimal medium. These heterokaryons were unstable and readily dissociated into their nuclear components. Under appropriate conditions, the parental nuclei of an heterokaryon fused. The homokaryon so obtained was unstable and segregated into various types of auxotrophic and prototrophic recombinants.

Candida↗