Search PubMed⌕ Search

Biomedical subjects

B Blondel

Publications and source records attributed to B Blondel.

At least 127 records · Page 7Linked to original sources
PubMed1987

[Episiotomy and prevention of complete and complicated tears. A study in 3 European countries].

The rates of third-degree tears in deliveries with and without episiotomy were compared in five samples: three French samples, a Belgian one and a Dutch one. Those samples corresponded to 48,430 single vaginal deliveries. The rates of episiotomy ranged from 29.3% to 54.2%. The results demonstrate that the risk of third-degree tears in vertex uncomplicated deliveries without episiotomy is low, and that in numerous cases third-degree tears are not prevented by an episiotomy. When uncomplicated deliveries of primipara were considered, results from four of the five samples showed that third-degree tears were not significantly more frequent in deliveries without episiotomy.

Belgium↗
PubMed1986

A poliovirus neutralization epitope expressed on hybrid hepatitis B surface antigen particles.

The hepatitis B virus (HBV) envelope protein carrying the surface antigen (HBsAg) is assembled with cellular lipids in mammalian cells into empty viral envelopes. In a study to evaluate the capacity of such particles to present foreign peptide sequences in a biologically active form, in-phase insertions were created in the S gene encoding the major envelope protein. One of the sequences inserted was a synthetic DNA fragment encoding a poliovirus neutralization epitope. Mammalian cells expressing the modified gene secreted hybrid particles closely resembling authentic 22-nanometer HBsAg particles. These particles reacted with a poliovirus-specific monoclonal antibody and induced neutralizing antibodies against poliovirus. The results indicate that empty viral envelopes of HBV may provide a means for the presentation of peptide sequences and for their export from mammalian cells.

Animals↗
PubMed1986

Causes of death among adolescents and young adults in the countries of the European Community and trends, 1960-1980.

Recent trends in mortality among adolescents and young adults in 10 countries belonging to the European Community are described. Data are from official sources for the countries concerned. "Causes of death for age groups 10-14, 15-19 and 20-24 are analyzed by sex for the Community as a whole and for each country separately. Trends over the period 1960-1980 are also analyzed. The marked increase in mortality rates between ages 10 and 20 is explained by the growing importance of traffic accidents. In some countries, however, traffic mortality has declined. Suicide levels though have increased everywhere." (SUMMARY IN FRE)

Adolescent↗
PubMed1986

Mutations conferring resistance to neutralization with monoclonal antibodies in type 1 poliovirus can be located outside or inside the antibody-binding site.

Antigenic variants resistant to eight neutralizing monoclonal antibodies were selected from wild (Mahoney) and attenuated (Sabin) type 1 infectious poliovirions. Cross-immunoprecipitation revealed interrelationships between epitopes which were not detected by cross-neutralization. Operational analysis of antigenic variants showed that seven of eight neutralization epitopes studied were interrelated. Only one neutralization epitope, named Kc, varied independently from all the others. This latter, recognized by C3 neutralizing monoclonal antibody, was present not only on infectious virions but also on heat-denatured (C-antigenic) particles and on isolated capsid protein VP1. Loss of the neutralization function of an epitope did not necessary result from the loss of its antibody-binding capacity. Such potential, but not functional, neutralization epitopes exist naturally on Mahoney and Sabin 1 viruses. Their antibody-binding property could be disrupted by isolating antigenic variants in the presence of the nonneutralizing monoclonal antibody and anti-mouse immunoglobulin antibodies. Single-point mutations responsible for the acquisition of resistance to neutralization in the antigenic variants were located by sequence analyses of their genomes. Mutants selected in the presence of C3 neutralizing monoclonal antibody always had the mutation located inside the antibody-binding site (residues 93 through 103 of VP1) at the amino acid position 100 of VP1. On the contrary, antigenic variants selected in the presence of neutralizing monoclonal antibodies reacting only with D-antigenic particles had mutations situated in VP3, outside the antibody-binding site (residues 93 through 103 of VP1). The complete conversion of the Mahoney to the Sabin 1 epitope map resulted from a threonine-to-lysine substitution at position 60 of VP3.

Amino Acid Sequence↗
PubMed1986

[Prenatal surveillance and outcome of pregnancy according to the origin of women born outside continental France].

From national surveys on representative samples of births, in France, in 1972 and in 1981, prenatal care and outcome of pregnancy among immigrant women--having been born outside continental France--have been studied. In spite of an increase in the number of prenatal visits, between 1972 and 1981, foreign women born in North Africa or in other non-European countries in 1981 had still less prenatal visits than women born in continental France. Few differences in outcome of pregnancy according to the women's birthplace in 1981 are shown, preterm deliveries' and birthweight less than 2,500 g rates had decreased between 1972 and 1981 among most groups of women. Nevertheless, in 1981 stillbirth was more frequent among foreign women, especially women born in North Africa.

Algeria↗
PubMed1985

Some characteristics of antenatal care in 13 European countries.

This study compares the organization of antenatal care in 13 European countries having a fetal and infant mortality rate below 20 per 1000. The countries differ in the number of prenatal visits, the role performed by midwives and the use of home care. It shows that there is no single model of antenatal care among countries having similar fetal and infant mortality.

Ambulatory Care↗
PubMed1985

Mapping of type 1 poliovirus neutralization epitopes.

Several independently variable neutralization epitopes were identified on type 1 poliovirus by testing various field isolates with a panel of homotypic monoclonal antibodies. According to their distribution among viruses tested, neutralization epitopes were classified as strain-specific or variable (V) and cross-reacting or constant (K). Operational, relationship between different neutralization epitopes was analysed by selecting mutants resistant to neutralization with monoclonal antibodies from wild Mahoney and attenuated Sabin type 1 poliovirus. The results of this study and their implication in the characterization of poliovirus antigenic structure by neutralization epitope formulae is discussed.

Antibodies, Monoclonal↗
PubMed1985

Antigenic modification of attenuated Sabin type 1 poliovirus by in vitro passages at supraoptimal temperatures.

Mutants were selected from Sabin type 1 attenuated poliovirus (LSc2ab strain), capable of growing at a high temperature (39.5 degrees C). They proved to be neurovirulent for monkeys. No correlation was found between neurovirulence and antigenic structure in Sabin type 1 virus as demonstrated by the analysis of the neutralization epitope formulae of thermo-resistant, neurovirulent mutants derived from LSs2ab strain. The lack of correlation between the antigenic pattern of the virus and the virulence was also confirmed by a mutant resistant to neutralization with monoclonal antibodies derived from the wild Mahoney parent of the Sabin type 1 virus. This mutant continued to be neurovirulent in spite of the complete conversion of its neutralization epitope formula to the Sabin virus pattern.

Animals↗
PubMed1985

Energy dispersive X-ray microanalysis of zinc and calcium in organelles of insulin-producing cells of the mouse, rat, and a fish.

By means of energy dispersive X-ray microanalysis in the scanning-transmission electron microscope, spectra were obtained from quick-frozen, cryo-ultramicrotome cut, freeze-dried sections of insulin cells from a fish and a mouse. It was shown that both zinc and calcium are present in significant quantities in native islet-cell beta-granules. In the beta-granules of the rat RINm5F insuloma cells calcium, but not zinc, seemed to accumulate; the zinc contents in the secretion granules of these neoplastic beta-cells were probably below the detection limit.

Animals↗
PubMed1984

Regulation of Ca2+ transport by isolated organelles of a rat insulinoma. Studies with endoplasmic reticulum and secretory granules.

The regulation of extramicrosomal Ca2+ concentration maintained by suspensions of rat insulinoma microsomes was studied using Ca2+-selective minielectrodes. The Ca2+-transporting activity was MgATP dependent and correlated with the endoplasmic reticulum marker NADPH-cytochrome c reductase. When incubated in a high KCl medium containing Mg2+ and phosphate, the microsomes lowered [Ca2+] within less than 10 min to around 0.2 microM. They had a high Ca2+-sequestering activity since they were able to take up and retain several small Ca2+ additions. No evidence for a Na+/Ca2+ countertransport was obtained. The accumulated Ca2+ was released by the Ca2+ ionophore A23187 or upon transforming ATP into ADP using glucose plus hexokinase. The addition of ADP, at concentrations present in cells, resulted in a dose-dependent and reversible net Ca2+ efflux from the microsomes until a higher [Ca2+] steady state was reached. This was specific for ADP since GDP, UDP, CDP, IDP, and the nonhydrolyzable analogue methylene-ADP as well as AMP and cAMP did not reproduce the effect. Insulin secretory granules were unable to lower medium [Ca2+] or to take up a pulse addition of Ca2+. However, most of the large granular calcium content was released by A23187. The addition of Na+ and lowering or increasing medium pH by 0.2 pH unit did not induce Ca2+ uptake or efflux from the secretory granules. The results indicate that insulinoma endoplasmic reticulum but not insulin secretory granules may play a critical role in the regulation of cytosolic Ca2+. A variation in cellular ADP content following secretagogue addition might modulate Ca2+ fluxes across the endoplasmic reticulum and contribute in raising cytosolic Ca2+.

Adenoma, Islet Cell↗
PubMed1984

Streptozotocin-induced functioning islet cell tumor in the rat: high frequency of induction and biological properties of the tumor cells.

After a long latency, hormone-producing islet cell tumors are induced with high frequency by a single administration of streptozotocin and nicotinamide in the rats. Thus, pancreatic islets must be considered a target tissue for the tumorigenic, as well as diabetogenic, action of streptozotocin. These tumors are well-differentiated and resemble normal islet tissue, both morphologically and functionally, as they are rich in typical beta cells and release insulin in response to glucose, both in vivo and in culture. However, some noteworthy differences have been observed in comparison to normal tissue: (a) the release of large amounts of proinsulin after glucose stimulation, (b) the presence of granulated cells of uncertain classification, similar but not identical, to delta cells, and (c) the altered proportion in hormone content, which suggests a different sensitivity of the different islet cell types to the chemically induced transformation.

Adenoma, Islet Cell↗
PubMed1984

Neutralization epitope patterns of poliovirus strains isolated from paralytic cases.

Monoclonal antibodies were used in previous work to define neutralization epitopes (NE) of poliovirus during its natural variation upon interhuman passages. Two kind of NE were found: constant (K) epitopes, present on practically all poliovirus strains of the same serotype, and variable (V) epitopes, which were strain-specific either for wild-laboratory strains (Mahoney, MEF1, and Saukett) (VW epitopes), or for attenuated Sabin strains (VS epitopes), or for attenuated Sabin strains (VS epitopes). In the present paper we analyzed the NE formulae of poliovirus strains of each of the three serotypes isolated from paralytic cases that have occurred after mass vaccination with oral poliovaccine (Sabin). Type 1 isolates from both the central nervous system and stools showed the existence of the four VW epitopes characteristic for Mahoney virus. However, in some cases, variation of the K epitope formula was noticed. As concerns the paralytic cases where type 2 poliovirus was isolated, the situation was more complex due to the existence of three different VS epitopes. Various patterns of VS epitopes were encountered, making difficult the definition of the strains origin. Most of the type 3 strains isolated from paralytic cases contained one or both VS epitopes, some of them having an identical NE formula to the Sabin type 3 vaccine virus. These data showed that the use of strain-specific neutralizing monoclonal antibodies for the characterization of strain origin is more complex than generally agreed. The multitude of NE coexisting on the same virus particle and their variation during viral replication in the human intestine call for cautious interpretation of the results obtained in poliovirus intratypic differentiation by neutralizing monoclonal antibodies.

Antibodies, Monoclonal↗
PubMed1983

Detection by monoclonal antibodies of an antigenic determinant critical for poliovirus neutralization present on VP1 and on heat-inactivated virions.

Hybridoma cell lines were established against poliovirus type 1 (Mahoney) heat-denatured virions (C particles). Each anti-C monoclonal antibody (McAb) immunoprecipitated specifically one of the individualized poliovirus capsid polypeptides VP1, VP2, or VP3. One of the anti-C McAb (C-3), reacting with VP1, neutralized homologous virus and immunoprecipitated infectious D particles. Its properties have been compared to those of a neutralizing anti-D McAb (D-Ic). In contrast with the C-3 antigenic site, the D-Ic epitope was not present on C particles nor on individualized structural polypeptide. This demonstrates that C-3 and D-Ic epitopes represent two independent antigenic determinants, both critical for poliovirus neutralization.

Animals↗
PubMed1983

Regulation of immunoreactive-insulin release from a rat cell line (RINm5F).

1. An insulin-producing cell line, RINm5F, derived from a rat insulinoma was studied. 2. The cellular content of immunoreactive insulin was 0.19 pg/cell, which represents approx. 1% of the insulin content of native rat beta-cells, whereas that of immunoreactive glucagon and somatostatin was five to six orders of magnitude less than that of native alpha- or delta-cells respectively. 3. RINm5F cells released 7-12% of their cellular immunoreactive-insulin content at 2.8 mM-glucose during 60 min in Krebs-Ringer bicarbonate buffer. 4. Glucose utilization was increased by raising glucose from 2.8 to 16.7 mM. There was, however, no stimulation of immunoreactive-insulin release even when glucose was increased from 2.8 to 33.4 mM. A small stimulation of release was, however, found when glucose was raised from 0 to 2.8 mM. 5. Glyceraldehyde stimulated the release of immunoreactive insulin in a dose-dependent manner. 6. At 20 mM, leucine or arginine stimulated release at 2.8 mM-glucose. 7. Raising intracellular cyclic AMP by glucagon or 3-isobutyl-1-methylxanthine stimulated release at 2.8 mM-glucose with no additional stimulation at 16.7 mM-glucose. 8. Stimulation of immunoreactive-insulin release by K+ was dose-related between 2 and 30 mM. Another depolarizing agent, ouabain, also stimulated release. 9. Adrenaline (epinephrine) inhibited both basal (2.8 mM-glucose) release and that stimulated by 30 mM-K+. 10. Raising Ca2+ from 1 to 3 mM stimulated immunoreactive-insulin release, whereas a decrease from 1 to 0.3 or to 0.1 mM-Ca2+ lowered the release. 11. These findings could reflect a relatively specific impairment in glucose handling by RINm5F cells, contrasting with the preserved response to other modulators of insulin release.

Adenoma, Islet Cell↗
PubMed1983

Studies in vivo and in vitro on chemically-induced primary islet cell tumours and non-tumour endocrine pancreatic tissue.

Rat islet cell tumours induced by injection of streptozotocin and nicotinamide have been studied in vivo and after the establishment of monolayer cultures of tumour cells. During an intravenous glucose tolerance test, tumour-bearing rats had increased release of immunoreactive insulin, with a high proportion of proinsulin, as well as accelerated glucose disposal relative to control rats. The tumours were rich in immunoreactive insulin and somatostatin, poor in glucagon. Non-tumour pancreatic tissue or isolated islets contained 10% or less of the corresponding normal amounts of insulin whereas the islet content of somatostatin was unchanged and that of glucagon increased. This is best interpreted as a selective suppression of non-tumour B cells, further supported by the observation that the initially reduced insulin release and content of non-tumour islets were partially restored after 2 days in tissue culture. In monolayer culture, tumour cells maintained insulin production and acute responsiveness to glucose for prolonged periods. There was no sign of cell proliferation. It is concluded that primary, chemically-induced insulin-producing pancreatic islet cell tumours retain several features characteristic to normal B cells and continue to influence glucose homeostasis in vivo.

Adenoma, Islet Cell↗