[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%).

[Contribution of in situ hybridization to chromosomal analysis]

In situ hybridization (ISH) is a new technique which allows localizing on chromosomes a molecule of DNA homologous to a given sequence of nucleic acids. It permits to improve the chromosomal analysis by marking any sequence of nucleic acids in interphase or metaphase. It opens new prospects for chromosomes mapping, study of evolution, chromosomal diagnosis, the role of oncogenes and chromosomal mechanics.

The measurement in vivo of the rate of unesterified cholesterol exchange between rat plasma and erythrocytes

In order to investigate the rate of unesterified cholesterol exchange between plasma and erythrocytes in vivo, cholesterol labelling in rats was achieved in one of the following ways: intravenous injection of cholesterol-labelled erythrocytes, subcutaneous injection of labelled acetate, feeding of labelled cholesterol. The specific activity of the unesterified cholesterol was measured at intervals up to 24 h and a kinetic analysis of the data was performed. It assumes that both the cholesterol in the erythrocytes and the unesterified cholesterol in the plasma were homogeneous pools. The rate constants obtained for the movements of unesterified cholesterol from erythrocytes to plasma and from plasma to erythrocytes were not significantly different in the three labelling conditions (mean values: 0.26 and 1.5 h-1, respectively).

Inositol 1,4,5-triphosphate microinjection triggers activation, but not meiotic maturation in amphibian and starfish oocytes

Inositol 3,4,5-triphosphate (InsP3) brought about cortical granule exocytosis and elevation of a fertilization membrane, due to a rapid increase of free calcium in cytoplasm, when injected into oocytes of the amphibian Xenopus laevis arrested at second meiotic metaphase. The same result was observed when injection was performed into oocytes of the starfish Marthasterias glacialis arrested either at the first meiotic prophase or after completion of meiosis. Although meiotic maturation was induced in both animals by specific hormones which have been previously shown to release Ca2+ within cytoplasm, InsP3 microinjection into prophase-arrested oocytes did not release them from prophase block.

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.

[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.

Bilateral retinoblastoma with de novo constitutional balanced translocation t(2;9)(q11;p11)

The case of a 6-year-old boy with bilateral retinoblastoma (RB) and apparently de novo balanced translocation t(2;9)(q11;p11) is presented. The normality of 13q14 chromosome region has been confirmed using high resolution techniques and Esterase D assay. The hypothesis that this RB might be correlated to the translocation is discussed.

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.

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.

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.

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.

[Value of moxalactam in the treatment of meningitis: efficacy and meningeal diffusion]

15 bacterial meningitis (Haemophilus: 7, Meningococci: 3, Proteus: 1, Enterobacter: 2, E. coli: 1 and Klebsiella: 1) are treated with moxalactam. The diffusion of moxalactam into the cerebrospinal fluid is good and regular. Excellent clinical results are obtained.

[Genetic aspects of autosomal fragile sites. Apropos of 40 Cases]

We report forty cases of congenital autosomal fragile sites, which have been analysed genetically and cytogenetically in the light of previous reports in the literature. The nature of the lesion of DNA at the fragile site is unknown. In contrast with the fragile site Xq27 there is no particular phenotype associated with autosomal fragile sites. The incidence of early spontaneous abortion and of chromosomal abnormalities in the offspring of carriers of these inherited autosomal fragile sites suggests the possibility of prenatal diagnosis.

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.

X-autosome translocations: cytogenetic characteristics and their consequences

To define the principal characteristics of X-autosome translocations, the authors present a study of 105 cases, five of which are personal observations. The autosomal pairs 15, 21, and 22 are affected by t(X-Aut) more often than would be expected. The distribution of breakpoints on the X chromosome does not differ significantly from the expected distribution. The analysis of different patterns of inactivation seems to confirm that the inactivation could occur at random, but would be followed by a cellular selection favoring the better genetic balance. An estimate of the incidence of t(X-Aut) is proposed, based upon the conclusions that only one chromosome is susceptible to translocation in meiosis in both males and females and that all affected men will be sterile, as will be 50% of women.

The effects of membrane lipid order and cholesterol on the internal and external cationic sites of the Na+-K+ pump in erythrocytes

cholesterol depletion alters the apparent affinity of the internal cationic sites and the maximal translocation rate but not the affinity of the external cationic sites of the Na+-K+ pump in human erythrocytes. To test whether these effects were mediated by a direct cholesterol-internal site interaction or by a change in membrane lipid order, the effects of five fluidizing amphiphiles (chlorpromazine, imipramine, benzyl alcohol, sodium oleate and sodium benzenesulphonate) on the kinetic parameters of the Na+-K+ pump were determined. The cholesterol removal and all the agents used induced dose-response decreases in membrane lipid order as measured by fluorescence polarization or ESR. Positive and neutral amphiphiles mimicked the effects of cholesterol removal on the affinity of the internal sites of the pump and to a lesser extent on the maximal translocation rate. Anionic amphiphiles had no effect on internal sites, probably because they distributed preferentially within the outer leaflet on the membrane. These results indicate that cholesterol controls the affinity of the internal sites of the Na+-K+ pump by altering the membrane lipid order. In contrast, neither cholesterol depletion nor the agents used altered the affinity of the external sites of the Na+-K+ pump. This difference in sensitivity to membrane lipids order suggests that internal and external cationic sites, although borne by the same protein, are in different lipid environments.

[Individual variability of associations between acrocentrics (author's transl)]

We studied the quantitative and qualitative variation of associations between acrocentric chromosomes in four subjects on a period of ten months; results show a definite tendency of association in a same subject, tendency which is reproducible and clear. Even though each individual has a determined rate of associations, the number of associated chromosomes and the number of associations themselves do not vary with months. Furthermore, associations do not appear at random; indeed, they have a wide spectrum of variations from one subject to the other but if we take the subjects individually, their associative rate concerning each chromosome do not change with months. Therefore, the phenomenon of association could be viewed as a biological characteristic of each individual.

Alterations in human erythrocyte shape and the state of spectrin and phospholipid phosphorylation induced by cholesterol depletion

Cholesterol depletion of erythrocytes, obtained after incubation with phosphatidylcholine vesicles, induces in most of the experiments: (1) a discocytestomatocyte transformation as observed by scanning electron microscopy; (2) a specific decrease in spectrin phosphorylation of intact erythrocytes; (3) an increase in lipid phosphorylation. It is concluded that the effect of cholesterol on erythrocyte shape is probably mediated through its action on the activity o of membrane-bound enzymes, proteases or kinases.