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Biomedical subjects

P Pothier

Publications and source records attributed to P Pothier.

84 records · Page 5Linked to original sources
PubMed1980

Characterization of isolated villus and crypt cells from the small intestine of the adult mouse.

Suspensions of sequentially isolated villus and crypt cells were obtained in order to study certain biochemical changes associated with differentiation of epithelial cells in the small intestine of the mouse. Microscopic observation of the various cell fractions reveals that the epithelial cells detach as individual cells or small sheets of epithelium from the tip to the base of the villus, whereas cells in the crypt regions are separated as entire crypt units. The isolated cells retain their ultrastructural integrity as judged by electron miscroscopy. Chemical characterization of the various fractions shows that the total cellular protein content, expressed in activity per cell, remains relatively constant throughout the villus region followed by a noticeable drop in the crypt zone. On the other hand, sharp variations in values of cell DNA content are observed in the crypt zone depending on the reference of activity being used. Activity profiles of several brush border enzymes confirm the biochemical changes that occur during the migration of cells from the crypt to the villus tip, as observed in other species, with maximum activity of sucrase in the mid-villus region, of glucoamylase, trehalase, lactase and maltase in the upper third region, and of alkaline phosphatase at the villus tip. Forty-eight-hour suspension cultures of cell fractions corresponding to cells at the base of the villus and crypt zones show a moderate decrease in protein and enzyme activities to approximately 70% of their original value, with DNA content remaining stable throughout the incubation period. The use of biochemical activities as indicators of cellular integrity during cell culture is discussed.

Animals↗
PubMedDate not supplied

Identification of T-cell epitopes adjacent to neutralizing antigenic domains on the fusion protein of respiratory syncytial virus.

F glycoprotein has been identified as an important target structure in the immunological response following respiratory syncytial virus (RSV) infection. Two sequential B epitopes corresponding to amino acids 200 to 225 and 255 to 278 have already been defined with anti-RSV rabbit serum. The T helper response to peptides which belong to these sequences was investigated in this study. Proliferative T-cell responses to these peptides were analysed in BALB/c mice (H-2d) and others strains: SJL (H-2s), C3H/He (H-2k), B10.BR (H-2k) and C57BL/6 (H-2b). By using various strategies, two T-cell epitopes were identified in the amino acid 200 to 225 and 255 to 278 regions, close to a neutralizing epitope. The T-cell responses to these peptides were H-2- restricted. In addition, the peptide 255-278 was able to stimulate T cells that responded to a subsequent immunization with F glycoprotein in vitro.

Animals↗
PubMedDate not supplied

Selection and characterization of two specific monoclonal antibodies directed against the two variants of human herpesvirus-6.

Monoclonal antibodies (mAbs) specific for human herpesvirus-6 (HHV6) proteins were derived from the splenocytes of mice immunized with HHV6 TAN isolate-infected peripheral blood mononuclear cells. The two mAbs 8C8 and 7C7 reacted by means of immunofluorescence and immunoperoxidase assays with both variant A and variant B isolates giving two different staining patterns. In infected cells, cytoplasmic diffuse staining was observed with mAb 8C8, whereas intense nuclear staining was obtained with mAb 7C7. These different locations of viral target proteins were confirmed by confocal microscopy. The mAb 8C8 reacted with a family of six glycoproteins designated as the gp72 complex in the case of variant A strains and gp63 complex in the case of variant B strains. The endoglycosidases H and F reduced those glycoproteins to a putative precursor molecule of 58 kDa. The mAb 7C7 reacted with 116 and 109 kDa proteins with the two HHV6 variants. These two mAbs did not neutralize virion infectivity in the absence of complement. No cross-reactivity was observed when these mAbs were used in immunoperoxidase assay and immunoblotting against the proteins of human cytomegalovirus or other human herpesviruses. Thus, the two mAbs 8C8 and 7C7 may be valuable tools for the diagnosis and biological investigation of HHV6 infections.

Animals↗
PubMedDate not supplied

Ontogeny of EGF receptors during postnatal development of mouse small intestine.

This study was aimed at characterizing epidermal growth factor (EGF) receptors during postnatal development of the maturing mouse small intestine at a time when this tissue is in the constant presence of high levels of intraluminal EGF. Binding studies with [125I]EGF on isolated epithelial cells demonstrate the continued presence of EGF receptors along the entire length of the small intestine with minimal binding at birth (3.67 +/- 0.30%/mg protein) and increasing steadily throughout postnatal life to reach adult values (10.39 +/- 0.90%/mg protein) by the 26th day, with maximum binding on the 21st day (13.4 +/- 2.2%/mg protein). This EGF binding pattern is similar for all three segments studied but was more pronounced for duodenum and jejunum, especially from day 14 on when binding capacity is more elevated in the proximal segments than in the ileum. Competition-inhibition curves of [125I]EGF by EGF reveal the presence of two classes of binding sites for which the number of sites and affinity constants are lower at birth than in adults. The continued presence of EGF receptors in mouse small intestine throughout the postnatal period thus provides support for the possible role of EGF as a modulator in the functional development of the maturing gastrointestinal (GI) tract.

Aging↗
PubMedDate not supplied

Differential distribution of digestive enzymes in isolated epithelial cells from developing human fetal small intestine and colon.

The human fetal colon has morphological and biochemical characteristics similar to that of the small intestine during development. A comparative study of these two organs was undertaken by selectively isolating their respective epithelium at different ages of gestation. Histological and biochemical analysis revealed a complete and selective removal of the epithelium from the underlying tissue regardless of their stage of development. Intestinal and colonic epithelial cells showed substantial differences with respect to protein content and distribution. All brush border membrane enzymes studied were present in the colon, although in much lower quantities than in the corresponding intestine. Between 90 and 99% of total disaccharidases, glucoamylase and gamma-glutamyl transpeptidase activities were recovered in the isolated cells. Epithelial content and distribution of alkaline phosphatase (ALP) activity differed markedly, however, between these two tissues. More than 45% of intestinal ALP activity was of nonepithelial origin at 15 weeks, and this percentage increased in a craniocaudal fashion to reach greater than 93% in the 18-week-old colon. Inhibition studies using phenylalanine and levamisole showed that these intestinal and colonic isoenzymes are similar in nature although they differ in their respective distribution. The use of pure fractions of epithelial cells provides an ideal system in which to compare specifically the functional development of intestinal and colonic epithelium.

Alkaline Phosphatase↗
PubMedDate not supplied

Twenty years: a great beginning.

The only nursing organization whose major focus is the psychiatric mental health needs of severely emotionally disturbed children, adolescents and their families and the promotion of mental health of children, adolescents, and their families, has turned 20 this year. The author's purpose is to review the history and accomplishments of Advocates for Child Psychiatric Nursing, Inc. (ACPN), and to make some projections for future action by this nursing specialty organization.

Adolescent↗
PubMedDate not supplied

[Investigation of an outbreak of norovirus gastroenteritis in a geriatric hospital].

In aged-care facilities, gastroenteritis outbreaks are responsible for big trouble in the management of cares to the elderly. In November 2002, a gastroenteritis outbreak was observed in 5 of the 6 wards of the geriatric hospital La Charité, University Hospital of Saint-Etienne, France, with an attack rate of 38.5% in the elderly (70 infected from 182 patients) and of 26.0% in the nursing staff (40 infected from 154 agents). The outbreak lasted 30 days with a peak corresponding to 79.8% of the cases between the 11(th) and the 20(th) of November. The first cases were observed in the two short-term-care wards; then, the outbreak spread rapidly to 3 of the 4 long-term care units. Health care workers were contaminated later than the elderly (P < 0.001 by Kruskal-Wallis test). A self-administered questionnaire was documented by most of the nursing staff; the most frequently observed clinical symptoms in this population were nausea (82.5%), abdominal pain (80.0%), diarrhoea (70.5%), asthenia (67.5%) and vomiting (62.5%). Thirty-five percent of the health care workers ceased their work. The causative agent of the gastroenteritis was identified by RT-PCR in the stools of 5 aged persons as a norovirus close to the Lordsdale strain (genogroup II). These findings illustrate the respective role of elderly and health care workers in the spread of the gastroenteritis outbreak inside the geriatric hospital.

Adult↗
PubMedDate not supplied

[Bactericidal activity of amoxicillin and cefaclor in an "in vitro" kinetic model (author's transl)].

The bactericidal activity against Staphylococcus aureus 290-P, Escherichia coli NIHJ-JC2 and Klebsiella pneumoniae ATCC-10031 (10(6)/ml) was studied during 24 h, using an in vitro kinetic model which simulates the drug concentrations occurring in human serum after oral doses of amoxicillin (0.5 g or 1 g) or cefaclor (0.25 g or 0.50 g), 2 or 3 times a day. After the first antibiotic exposure, a high level of bactericidal activity (99-99.9%) was observed. Complete bactericidal activity was observed in all cases against S. aureus, but only after 3 times per day exposures in the case of E. coli and K. pneumoniae. Twice per day exposures of amoxicillin or cefaclor were invariably ineffective for these two species of Enterobacteriaceae (10(9) bacterial survivors/ml). These findings were related to subinhibitory concentrations which were or not able to prevent or reduce the bacterial regrowth after the first exposure of the antibiotics.

Amoxicillin↗