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Biomedical subjects

L Lafleur

Publications and source records attributed to L Lafleur.

At least 55 records · Page 3Linked to original sources
PubMed1974

Yersiniosis in children.

Sixty-five strains of Yersinia enterocolitica were isolated from stool specimens obtained from 35 patients over a 12-month period. The microbiologic characteristics and drug sensitivities are reported and the clinical patterns of disease associated with the organism are described. Gastroenteritis affecting infants and young children is the most frequent manifestation. The data for 1972 show the same epidemiological trend as in preceding years.

Adolescent↗
PubMed1974

Survey on the incidence of Yersinia enterocolitica infection in Canada.

Data pertaining to 278 cultures of Yersinia enterocolitica isolated in Canada are summarized in this paper. Of this amount, 256 were isolated from humans, whereas 22 were of nonhuman sources. The typing of these cultures is presented together with their geographical location. Y. enterocolitica serotype O:3 biotype 4, phage type 9b, was practically the only serotype present in the Province of Quebec. This serotype O:3 was also predominant in Ontario, followed by serotypes O:5,27 and O:6,30; other serotypes were seldom isolated. In the central and western areas of Canada, Y. enterocolitica was occasionally isolated; the strains were indole-positive, serotypes O:5,27, O:8, and O:4,32.

Adult↗
PubMed1973

Restriction of specificity in the precursors of bone marrow-associated lymphocytes.

Previous work has shown that the immediate precursor of B lymphocytes (PB cell) has many properties that distinguish it from both B lymphoctes and hemopoietic stem cells. Size, density, tissue distribution, and sensitivity to cytotoxic antisera differ for each type of cell. The work described here was designed to study three aspects of the differentiation of PB cells. First, since PB cells probably have immunoglobulin surface receptors, fluorescein-labeled anti-immunoglobulin antiserum was used in an attempt to investigate directly the physical properties of PB cells. The use of this labeled antiserum revealed a population of cells with properties similar to the PB cells defined by the functional assays. Second, the differentiative potential of PB cells was studied by comparing the size of the total population of PB cells, as determined with fluorescein-labeled anti-immunoglobulin antiserum, to the size of the population of PB cells responding in a functional assay with a specific antigen. The cells responding in the functional assay represent only 0.1% of the total population of PB cells. This observation suggests that PB cells are not pluripotent stem cells of the immune system. Finally, the kinetics of the differentiation of PB cells to B lymphocytes was studied. The differentiation to mature lymphocytes involves at least one intermediate stage in which cells larger than mature B cells are active in a functional assay for B cells. These large B cells are present in irradiated mice soon after transplantation of PB cells, but by 20 days the majority of the B cells are typical small lymphocytes.

Animals↗
PubMed1972

A quantitative assay for the progenitors of bone marrow-associated lymphocytes.

A cell transfer assay system was developed to study the precursors of bone marrow-associated (B) lymphocytes in the adult mouse. The rationale of the assay is to inject into irradiated mice a cell suspension depleted of B lymphocytes, to wait a period of time to let precursor cells differentiate to B lymphocytes, then to correlate the number of B cells present in the recipient mice with the number of precursor cells injected. The assay as described was shown to be linear in the range of 10(5)-3 x 10(6) fractionated bone marrow cells. Kinetic studies indicated that precursor cells start producing detectable numbers of B cells within 3 days after transplantation; B cell activity then increases with a doubling time of 24 hr. Physical characterization of that precursor cell has shown that it is lighter and sediments faster than small lymphocytes. Precursor cells were found in bone marrow and spleen but could not be detected in peripheral lymph nodes. Results of physical analysis also indicate that the precursors of B lymphocytes described here may not be pluripotent stem cells for the immune system.

Animals↗
PubMed1966

[Salmonellosis in children: study of 95 cases in the Hospital Ste-Justine, Montreal, in 1963-1964].

A retrospective study was done in children in whom salmonellosis was confirmed by laboratory findings with the aim of reviewing etiology, epidemiology, clinical manifestations and therapy. The 15 serotypes most frequently isolated from stool, and in exceptional cases from urine, are discussed. If patients with typhoid fever are excluded, only one patient (who subsequently died) had a blood culture positive for Salmonella, specifically S. enteritidis.No seasonal or other peaks of incidence were noted. Age appeared to be important; of 81 patients with gastroenteritis, 30 were less than 6 months old.Two children in the older age group developed complications; one with appendicitis required surgery.Ten strains of Salmonella out of 23 tested by the disc method showed in vitro resistance to ampicillin on primary isolation.Acquired in vitro resistance to one or more antibiotics appeared to develop with six Salmonella strains reisolated from patients after or during antibiotic treatment.In several children the stool cultures remained positive after clinical signs had disappeared. These findings strongly suggest that, even though antibiotic therapy may improve the symptoms of Salmonella infection, it does not decrease the number of carriers during the convalescent period.

Adolescent↗
PubMedDate not supplied

[In vitro differentiation of B lymphocytes].

In order to find if lymphoid colony-forming cells in the mouse are precursors of lymphocytes or are more differentitaed cells with a high proliferative capacity, their distribution between spleen and lymph node was compared to that of mitogen-sensitive B lymphocytes and that of precursurs of B lymphocytes assayed in mass cultures. The results and the responses to culture conditions suggest that these cell populations are different from each other.

Animals↗