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Biomedical subjects

B Blondel

Publications and source records attributed to B Blondel.

At least 145 records · Page 8Linked to original sources
PubMed1983

Localization of a poliovirus type 1 neutralization epitope in viral capsid polypeptide VP1.

Poliovirus type 1 cDNA sequences coding for viral capsid polypeptide VP1 were inserted into the beta-lactamase sequence of Escherichia coli plasmid pBR322. Resulting recombinant plasmid pSW119 expressed in Escherichia coli a VP1-beta-lactamase fusion protein that reacted with antibodies raised against poliovirus capsid polypeptide VP1 and with a monoclonal poliovirus type 1 neutralizing antibody, C3. Deletions of various lengths were generated within the VP1 sequence. The hybrid proteins expressed by the deleted plasmids did not react any more with C3 when the region of VP1 amino acids 95-110 (poliovirus nucleotides 2,754-2,806) was deleted. Therefore, the C3 epitope responsible for virus neutralization is most probably located in this region of the capsid polypeptide.

Amino Acid Sequence↗
PubMed1983

Natural variation of poliovirus neutralization epitopes.

Poliovirus-neutralizing monoclonal antibodies were prepared against type 1, type 2, and type 3 wild laboratory (Mahoney, MEF1, and Saukett) and Sabin vaccine strains. Fifty-five poliovirus laboratory strains and field isolates were assayed by neutralization index test with a panel of homotypic monoclonal antibodies. A total of 27 monoclonal antibodies were used. Two categories of neutralization epitopes were found, i.e., cross-reacting (K), which is present on almost all strains of the same serotype, and strain-specific (V, variable), either wild (VW) or Sabin (VS). Several distinct neutralization epitopes were defined for each of the three poliovirus serotypes in almost every category. The study of antigenic variation of the Sabin type 1 vaccine virus during replication in human intestine showed that the VS neutralization epitope may be lost and even replaced by the VW epitopes of the parental Mahoney virus. A late isolate from a vaccine-fed infant recovered the complete neutralization epitope pattern of the Mahoney strain. Upon in vivo virus replication, a different kind of antigenic variation was also detected in which an epitope lost its function in virus neutralization but kept its antigenic conformation unaltered. Neutralization epitope analysis demonstrated that the presence of VS epitopes on a field isolate suggests the Sabin origin of the strain when the isolate displays the same epitope pattern as the original Sabin virus, or confirms it when the VS epitope(s) is mutually exclusive of VW epitopes. The lack of VS epitopes on a field isolate does not rule out its being of Sabin origin.

Antibodies, Monoclonal↗
PubMed1983

Induction of neutralizing antibodies by type 1 poliovirus VP1 capsid polypeptide.

Sera against purified VP1, VP2, and VP3 poliovirus capsid polypeptides of type 1 poliovirus were prepared in rabbits. Each serum was demonstrated to be specific for the polypeptide against which it was raised by immunoprecipitation with labeled, individualized capsid polypeptides. One of the anti-VP1 sera had a neutralizing capacity against type 1 poliovirus. It was the only one which reacted in immunoprecipitation with D-antigenic infectious particles.

Animals↗
PubMed1983

[Early discharge of women after delivery. Results of an opinion survey among patients and unit personnel].

Women's and maternity staff's opinion about early discharge and home care after hospital delivery was studied in 1981 in an university clinic; 100 pregnant women and 100 newly delivered mothers filled in a questionnaire, the former during an antenatal visit, the latter during their stay in hospital after delivery; and so did all the staff of the maternity unit. We found that 28% of pregnant women, 22% of newly delivered mothers and 25% of maternity staff were in favour of a short stay in hospital after delivery followed by home care. The main reasons for disapproving a short postnatal stay were medical safety, need for rest and fear of being alone with the baby. For the women approving of early discharge the best duration of hospital stay was 2 or 3 days. Rather more doctors, head nurses and midwives than nurses, auxillary nurses and ancillary staff approved a short stay in hospital after delivery. It seems that the opinion of the maternity staff was not linked to changes in working conditions that this new organization would introduce. We consider that the women's preference should be given priority in deciding early discharge after delivery, when there is no medical contra-indication. Home care could be a useful transition between hospitalization and being alone at home; for instance health visitors could give advice about breastfeeding, infant care and birth control. But before generalizing this type of care it would be important to evaluate the medical, economic and psycho-social consequences.

Female↗
PubMed1982

[Structural polypeptide VP1 in poliovirus type 1 induced by neutralizing antibodies].

Anti-type 1 (Mahoney) poliovirus neutralizing antibodies were obtained by immunizing rabbits with structural polypeptide VP1. This polypeptide was isolated from the virion by PAGE-SDS electrophoresis and extracted from the gel by electroelution. Anti VP2 and anti VP3 sera prepared in the same was did not display any significant antipolio neutralizing activity.

Antibodies↗
PubMed1982

Impact of the French system of statutory visits on antenatal care.

A survey of a representative sample of births in France in 1976 showed that the great majority of women receive at least the minimum antenatal care laid down by law: 4% of women missed one of the three statutory visits linked to payment of the antenatal allowance and 6% missed the fourth visit that should take place in the ninth month. A smaller study conducted in two hospitals, one in the Paris region and the other in Nord-Pas-de-Calais, showed that the date of the first visit did not depend on a knowledge of the regulations. In one of the hospitals, where about 95% of women made more than the four statutory visits, the actual number of visits made was independent of a knowledge of the statutory number, In contrast, in the other hospital, where the mean number of visits was nearer to the statutory minimum, about half the women who said that four visits were required made exactly that number of visits and about half of those who gave three as the number made three visits.

Appointments and Schedules↗
PubMed1982

The possible importance of contact between pancreatic islet cells for the control of insulin release.

Insulin secretion was studied using adult rat intact islets, dissociated isolated islet cells, and isolated islet cells that had been allowed to reaggregate. The three preparations were maintained for 2 h in tisue culture medium at 37 C in order to allow for equilibration after the isolation procedures and to permit restoration of contacts between the reaggregated cells. The isolated cells appeared well preserved at the ultrastructural level. Evidence for intimate contacts between the reaggregated cells was demonstrated by the reappearance of gap junctions between adjacent cells. Basal insulin release (2.8 mM glucose) during 30 min was elevated in the isolated cell suspension but was restored to the level found in intact islets when isolated cells from the same population were reaggregated. The elevated basal release did not appear to be due to cell damage since there was a commensurate increase in the rate of insulin biosynthesis relative to intact islets. Although there was a marked stimulation of insulin release from the intact islets at 16.7 mM glucose, the response was smaller in the reaggregated cells and in the isolated cell suspension. All three preparations responded to elevated cAMP levels evoked by glucagon in the presence of 16.7 mM glucose. Similar results were obtained when insulin release was studied in various preparations derived from newborn rat pancreatic endocrine cells. Thus, basal insulin release was elevated in isolated cells, whereas cultures with cell contacts displayed lower basal insulin release. Taken together, the restoration of lower basal insulin release and the parallel appearance of contacts between the reaggregated cells suggest that these two phenomena are interrelated. Thus, cell contacts may be important in regulating basal insulin release. Whether such regulation is a consequence merely of cell association or of direct communication between cells remains to be established.

Aging↗
PubMed1982

Stimulation of insulin release by glucose in a transplantable rat islet cell tumor.

A subline of an x-ray-induced transplantable rat insulinoma has been studied in vivo and in vitro. Tumors grew rapidly after sc transplantation and were rich in insulin, but contained only small amounts of glucagon and somatostatin. Despite marked basal hyperinsulinemia, iv glucose administration caused a further increase in plasma insulin in tumor-bearing rats. When the pancreas was functionally excluded by ligation of supplying arteries, glucose still elicited a clear insulin response. In vitro, insulin release from perifused tumor fragments was stimulated by the combination of glucose and 3-isobutyl-1-methylxanthine, but not by glucose alone. In contrast, there was a clear stimulation of insulin release by glucose in primary monolayer cultures of tumor cells. This suggests a better functional capacity of the cultured cells compared to that of the tumor fragments. The results indicate that this transplantable rat islet cell tumor is a convenient source of large quantities of functional beta-cells.

1-Methyl-3-isobutylxanthine↗
PubMed1982

[Antenatal care and source of care during pregnancy (author's transl)].

The influence of the source of care on the unequalities in the number of antenatal visits was studied in a representative sample of births in France in 1976. The sources of care during pregnancy were divided into five groups according to number and qualification of the medical staff involved: hospital antenatal clinic, gynaecologist or obstetrician, general practitioner, hospital antenatal clinic and other practitioners, several practitioners outside hospital. The number of antenatal visits was related to the source of care. The inequalities in antenatal care according to maternal characteristics originated from inequal access to the most specialized sources of care and disparities in the number of visits within each source of care. Living in a big conurbation was a positive factor for consulting an obstetrician, going to hospital antenatal clinic and having a large number of visits; but even after allowing for this factor, there remained inequalities among women according to their socio-demographic characteristics or the source of care.

Adult↗
PubMed1980

Antenatal care and maternal demographic and social characteristics. Evolution in France between 1972 and 1976.

A study was carried out on representative samples of 11 254 births in France in 1972 and 4685 births in 1976. Women were interviewed after delivery to obtain information about the medical care they had received during pregnancy. Inadequate antenatal care was defined as: first antenatal visit after the first trimester of pregnancy, or total number of visits fewer than the required minimum, or no visit to an obstetrician or the hospital maternity team. In 1972, the problem of inadequate care occurred mainly in very young women, or in those of high parity or with short birth intervals when the father's social class had been taken into account. Social status was also an important factor independently of a woman's demographic characteristics. These inequalities persisted in 1976 despite the policy adopted in 1972 to improve antenatal care for high-risk women.

Adult↗
PubMed1980

Cyclic adenosine-3',5'-monophosphate stimulates islet B cell replication in neonatal rat pancreatic monolayer cultures.

A possible role for cyclic adenosine 3',5'-monophosphate (cAMP) in islet B cell replication was examined in neonatal rat pancreatic monolayer cultures. Islet cells deteriorated and insulin release decreased during 12 d of culture in medium with 5.6 mM glucose, whereas the cells survived and insulin release increased during culture in medium with 5.6 mM glucose plus the phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (IBMX, 0.1 mM), or in medium with 16.7 mM glucose with or without IBMX. IBMX also increased the mitotic index and stimulated dose-dependent increases in [(3)H]thymidine incorporation in nuclei of islet B cells in aldehydethionine stained radioautographs; maximal stimulation of B cell replication occurred with addition of 0.1 mM IBMX to 5.6 mM glucose (+170%, P < 0.001), and this increase was similar to that observed with 16.7 mM glucose (+185%, P < 0.001). Also, 8-bromo-adenosine-3',5-monophosphate, but not 8-bromo-guanosine-3',5'-monophosphate produced dose-dependent increases in islet B cell replication in medium with 5.6 mM glucose. Measurement of cAMP levels in the cultures revealed dissociations between effects on B cell replication and insulin release. Thus, addition of 0.1 mM IBMX, or 0.1 nM cholera toxin, to 5.6 mM glucose produced slightly greater increases in cAMP levels and B cell replication than did 16.7 mM glucose, whereas insulin release was increased significantly more with 16.7 mM glucose. Also, addition of 0.1 mM IBMX, or 0.1 nM cholera toxin, to 16.7 mM glucose stimulated further increases in cAMP levels and insulin release in the cultures, but no further increases in B cell replication. We conclude that (a) cAMP stimulates islet B cell replication, (b) cAMP may mediate the effects of glucose on B cell replication, and (c) mechanisms regulating B cell replication may be more sensitive to cAMP and/or different from those regulating insulin secretion.

1-Methyl-3-isobutylxanthine↗
PubMed1979

Establishment of rat pancreatic endocrine cell lines by infection with simian virus 40.

The feasibility of infection and transformation by SV40 (simian virus 40) of primary cell cultures derived from newborn-rat pancreas was investigated. As judged by the presence of intranuclear SV40 T-antigen, exposure to the virus resulted specifically in infection and transformation of epithelioid (predominantly endocrine) cells. The transformed cells were subcultured (more than 64 passages) and cloned. Culture medium and acid/ethanol extracts of the cells did not contain detectable amounts of immunoreactive insulin after the third subculture. However, inoculation of such SV40-transformed pancreatic cells into immunodeficient rats results in tumours in which insulin production was partially restored through the passage in vivo, since the tumour cells contained and synthesized small amounts of immunoreactive insulin which co-migrated with an insulin marker on gel chromatography. Interestingly, the transformed cells maintained under tissue-culture conditions produced a protein immunologically related to insulin, soluble in aqueous buffer but insoluble in acid/ethanol. This 3000-dalton protein is too large to be a translation product of the rat preproinsulin 9S mRNA. SV40-transformed pancreatic cells might prove useful in the investigation of the factors controlling and maintaining insulin biosynthesis.

Animals↗
PubMed1979

Motile events in pancreatic endocrine cells.

Monolayer cultures of neonatal rat endocrine pancreatic cells were examined by time lapse cinematography. Motion analysis revealed two major types of motile events. On one hand, particles (0.3 micrometers in diameter) tentatively identified as secretory granules were found to undergo back and forth saltatory movements along oriented pathways. The existence of such pathways was statistically validated by the large prevalence of angles close to either 0 degrees of 180 degrees between successive movements of the same particle. The movements occurred at a mean speed of 0.8 micrometers/sec. Glucose (16.7 mM) increased the frequency of such movements. Vincristine (10 microM) caused a progressive inhibition of saltatory movements, which may depend, therefore, on the integrity of the microtubular apparatus. On the other hand, areas of the cell boundary displayed contractile-like movements, which were stimulated by insulinotropic agents, such as glucose and the ionophore A23187. Cytochalasin B also affected this second type of motile event, which is thought to reflect the activity of actin-like microfilaments. These findings suggest that the microtubular apparatus serves as a guiding cytoskeleton for the oriented translocation of secretory granules, whereas the microfilamentous cell web may control the eventual access of the granules to exocytotic sites.

Animals↗