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Biomedical subjects

F Giraud

Publications and source records attributed to F Giraud.

At least 109 records · Page 6Linked to original sources
PubMed1985

Compartmentalization of Ca2+ in sickle cells.

Control (AA) and sickle cell anemia (SS) erythrocytes were loaded with Ca-chelator (Quin2 or Benz2) to increase the cellular exchangeable Ca2+ pool and to measure the Ca2+ exchange fluxes and the cytosolic ionized Ca2+ ([Ca]i) (Lew et al., 1982, Nature, 298, 478). The chelator incorporation induced a decrease in the ATP content which was smaller in SS than in AA cells and partially reversible upon reincubation in a chelator-free medium. The amount of trapped chelator was determined by two methods: 45Ca binding to the chelator in Ca-ionophore treated cells in Ca-EGTA buffers and [3H]Quin2 incorporation. A slight over-estimation of the chelator content was found with the second method but incorporation was the same in both types of cells. The kinetics of 45Ca equilibration and 45Ca release were used to measure Ca2+ fluxes and [Ca]i in oxygenated chelator-loaded cells. SS cells, as compared to AA cells, exhibited a moderate increase in Ca2+ fluxes (30-75%) but [Ca]i remained in the same range (about 20 nM). Thus the excess of Ca2+ found in SS cells is not available for the Ca2+ pump or the K+ channel a conclusion in agreement with that of Bookchin et al. (1984, Cell Calcium, 5, 277). Analysis of the 45Ca kinetics showed that in AA cells, exchangeable Ca2+ behaved as one compartment. In SS cells, the existence of a second slowly-exchangeable Ca2+ compartment was demonstrated. This latter (3-5 mumol/l cells) was independent of the concentration of the chelator and thus could represent exchangeable Ca2+ enclosed within the intracellular inside-out vesicles recently observed in SS cells (Williamson et al., 1984, J. Cell. Biol., 99, 430a). Alternatively, these two kinetic pools could reflect heterogeneity of the SS cell population.

Adenosine Triphosphatases↗
PubMed1985

[The register of stillbirths in Bouches-du-Rhône: evaluation after 3 years in operation].

A register of stillbirths from the Bouches-du-Rhône area in France was settled in 1982 with the double goal to provide epidemiological data on mortinatality and to help organizing a network of post-mortem examination. The results on 409 stillbirths out of 21.292 consecutive births are presented. The protocol for post-mortem examination included photography, radiography, karyotype and autopsy. A definitive conclusion was drawn in 75% of cases. The fetal anomalies recognized were isolated malformations (14,4%), multiple malformations (5,1%), syndromes (3,2%) and chromosomal anomalies (3,9%).

Autopsy↗
PubMed1985

[Small supernumerary chromosomes].

We report 23 cases of small supernumerary chromosome examined at the Medical Genetics Center of Marseille. Genetic counselling is depending on the origin of the additional chromosomal material. Among the different cytogenetic technics which are useful in such an identification in situ hybridisation is a new technic very helpful in some cases, especially iso p18.

Chromosome Aberrations↗
PubMed1984

Changes in morphology and in polyphosphoinositide turnover of human erythrocytes after cholesterol depletion.

Human erythrocytes were cholesterol-depleted (5-25%) by incubation with phosphatidylcholine vesicles in media containing Ca2+ at different concentrations (0, 28 nM, 5 microM or 1 mM). After removal of the vesicles, the cells were reincubated with [32P]phosphate in the same media. Control (incubated in buffer alone) and cholesterol-maintained erythrocytes (incubated with cholesterol/phosphatidylcholine vesicles) were treated similarly. Cholesterol depletion induced the conversion of the cells into stomatocytes III and spherostomatocytes and decreased the turnover rate of phosphatidylinositol phosphate and of phosphatidylinositol bisphosphate. None of these effects were observed in cholesterol-maintained cells. In cholesterol-depleted cells, they occurred without changes in the ATP specific activity or in the polyphosphoinositide concentrations. Moreover, these modifications of shape and of lipid metabolism were proportional to the extent of the cholesterol depletion and were independent of the external Ca2+ concentration. In contrast, other effects of cholesterol depletion, a decrease in the turnover rate of phosphatidic acid, a decrease in diacylglycerol and in phosphatidic acid concentrations were dependent on the external Ca2+ concentration. Thus it appears that the shape change was not correlated with a change in the concentrations of these phospholipids or of diacylglycerol and therefore cannot be explained by a bilayer couple mechanism involving these phospholipids. However, the spherostomatocytic transformation was correlated with the decrease in the turnover rate of the polyphosphoinositides, but not with the turnover rate of phosphatidic acid, suggesting a role for the turnover of the polyphosphoinositides in the maintenance of the erythrocyte shape.

Calcium↗
PubMed1984

Wilms' tumor, malformative syndrome, mental retardation and de novo constitutional translocation, t(7;13)(q36;q13).

An apparently balanced de novo constitutional translocation (7;13) (q36;q13) was detected on peripheral lymphocytes and fibroblasts of a 14-month-old boy. The patient presented a facial dysmorphism with hydrocephaly and mental retardation associated with a Wilms' tumor. A pure coincidence of random association cannot be ruled out but one can equally assert the plausibility of a minimal unnoticed deletion or a position effect.

Abnormalities, Multiple↗
PubMed1984

[Mental retardation linked to fragility of chromosome X: current knowledge].

The association of the fragile X chromosome with X-linked mental retardation is now well established. The main clinical features are mental retardation, typical facial dysmorphism and macroorchidism. Cytogenetically there is a fragile site in band Xq27-28 which can be demonstrated using specific techniques. The genetic studies are compatible with a X-linked dominant inheritance with an incomplete penetrance. A preliminary estimation of an overall frequency of 1: 2000 males for the fra(X)(q) condition is suggested.

Bromodeoxyuridine↗
PubMed1983

Alpha-adrenergically mediated changes in membrane lipid fluidity and Ca2/ binding in isolated rat liver plasma membranes.

Noradrenaline (0.1-5 microM, in the presence of 5 microM propranolol to block beta-receptors), ATP (100 microM) and angiotensin II (0.1 microM), which are thought to increase cytosolic Ca2+ concentration by mobilizing Ca2+ from internal stores, increased the lipid fluidity as measured by diphenylhexatriene fluorescence polarization in plasma membranes isolated from rat liver. The effect of noradrenaline was dose-dependent and blocked by the alpha-antagonists phenoxybenzamine (50 microM) and phentolamine (1 microM). The response to a maximal dose of noradrenaline (5 microM) and that to ATP (100 microM) were not cumulative, suggesting that both agents use a common mechanism to alter the membrane lipid fluidity. In contrast, the addition of noradrenaline (5 microM) along with the foreign amphiphile Na+-oleate (1-30 microM) resulted in an increase in membrane lipid fluidity which was equivalent to the sum of individual responses to the two agents. In the absence of Mg2+, reducing free Ca2+ concentration by adding EGTA increased membrane lipid fluidity and abolished the effect of noradrenaline, suggesting that Ca2+ is involved in the mechanism by which the hormone exerts its effect on plasma membranes. Noradrenaline (5 microM) and angiotensin II (0.1 microM) also promoted a small release of 45Ca2+ (16 pmol/mg membrane proteins) from prelabelled plasma membranes. The effect of noradrenaline was suppressed by the alpha-antagonist phentolamine (5 microM). It is proposed that noradrenaline, via alpha-adrenergic receptors and other Ca2+ -mobilizing hormones, increases membrane lipid fluidity by displacing a small pool of Ca2+ bound to phospholipids, removing thus the mechanical constraints brought about by this ion.

Adenosine Triphosphate↗
PubMed1983

Norepinephrine-induced loss of phosphatidylinositol from isolated rat liver plasma membrane. Effects of divalent cations.

Norepinephrine at 5 microM induces a rapid (60 s) and specific loss of phosphatidylinositol (PtdIns) when added to isolated rat liver plasma membranes. The hormone action is inhibited by the alpha-adrenergic antagonist phentolamine (20 microM). Depletion of Mg2+ and Ca2+ singly or in combination from the incubation buffer mimicks the hormone effect on PtdIns breakdown. No further effect on PtdIns degradation could be measured when norepinephrine was added to the cation-depleted buffers. Addition of the Ca2+ ionophore A23187 to the isolated membranes has no effect. It is concluded that PtdIns degradation can be provoked in isolated rat liver plasma membrane through alpha-adrenergic receptor activation and that this effect is dependent on divalent cations in the sense that loss of cations from the membrane allows degradation to commence.

Animals↗
PubMed1983

Prader-Willi syndrome and chromosome 15. A clinical discussion of 20 cases.

A chromosome 15 anomaly was observed in 12 of 20 patients, 17 of whom were clinically suspected of having Prader-Willi syndrome (PWS). The clinical features of eight cases with 15q11-12 deletion were very similar to those originally described in PWS. On the other hand, the group of normal karyotype patients is heterogeneous, and their features do not strictly correspond to the clinical definition of PWS. However, the hypothesis that PWS is associated with deletion of 15q11-12 can neither explain the apparently balanced translocations of chromosome 15 nor account for the small supernumerary metacentric chromosomes corresponding to an isochromosome 15 for band 15q11 observed in some cases.

Adolescent↗
PubMed1982

GENTIC: a computerized medical genetic case record system.

Gentic is a computerized system for the storage, recall, and analysis of data collected by the Medical Genetics Center in Marseille, France. It is based on a standard case report file that includes a full clinical description of all patients, results of cytogenetic investigations, and details of the genetic counseling provided. GENTIC has been used since 1975, and data on more than 5,000 families are accessible for study. This system has improved the quality of consultations, follow-up, and research. It provides data for epidemiological studies and for syndrome identification. This system is maintained at an annual cost of $3,000, salary costs not included, after an initial investment of $40,000.

Computers↗