Development of immunological capacity under germfree and conventional conditions.
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Biomedical subjects
Publications and source records attributed to L Mandel.
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The development of lymphoid populations in the omentum majus during the prenatal and postnatal life of the pig was studied. T lymphocytes, monocytes and mast cells were first found on the 40th day of gestation. B lymphocytes appeared on the 72nd day of gestation when the first macrophage aggregates were formed. Macrophages appeared to be the prerequisite for the formation of dense lymphatic areas (DLA's). At later stages T cells were observed only in the omentum of germfree pigs. DLA's of conventional pig omentum are filled exclusively with B cells.
Precolostral germfree piglets were perorally immunized with sheep erythrocytes daily, beginning on the 5th day of life. At different intervals the numbers of IgM, IgG and IgA antibody-forming cells were estimated in the spleens, lymph nodes and intestinal mucosa by the haemolytic plaque method. In the beginning of the response IgM antibody-forming cells were detected in intestinal mucosa and mesenteric lymph nodes. IgA plaque-forming cells appeared later and were predominant during the whole period in all organs tested. In all lymphatic organs tested the appearance of IgG antibody-producing cells followed that of IgA plaque-forming cells. The development of immunoglobulins and antibody of different isotypes in intestinal contents and sera was compared with the cellular kinetics found in these young animals after local stimulation.
The renewal time of intestinal epithelial cells was established using tritiated thymidine in 14-day-old conventional piglets as 96 hours, but 192 hours in germfree piglets. In germfree piglets, irradiated by single abdominal exposure to 60Co gamma-rays with 3.87 x 10(-1) C kg (= 1500 R), the first degenerative signs in the ileal epithelial cells were found on the 13th postirradiation day. Since that day, the columnar epithelial cells exhibited progressive degeneration changes in their ultrastructure. Quickly growing, substituting flat epithelial cells occurred beginning with the 15th day after irradiation and covered parts of the leveled denudated intestinal mucosa. These flat epithelial cells also exhibited degenerative changes.
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A brief review is given of the development of equipment used for rearing germfree animals in various laboratories and of our experience with designing germfree isolators and with the technology of rearing germfree piglets is presented. The philosophy of isolation as applied to the animal as a biological unit, the elimination of contamination and the theoretical prerequisites of isolation were considered by Reyniers (1943, 1959) and Trexler (1960).
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Experiences with female addicts in a feminist awareness group within a coed therapeutic community are reported. The group met for 16 months and was based on a variety of therapeutic techniques and educational presentations. The intervention resulted in more communication and trust among the women, increased interest in health-related concerns, a reduced sense of alienation, and gains in self-respect. The article discussed the issues and implications of resistance to the group, timing, development of indigenous leadership, training for feminist therapists, and the use of outside professional consultants in therapeutic communities.
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A germ-free isolator system was designed and constructed. It permits a sterile caesarean section and rearing of an infant under germ-free conditions. The system includes a plastic surgical and rearing isolator and two supply isolators; one of the supply isolators served as a transport mobile unit of staff participating in the sterile caesarean section and in the postnatal care of the germ-free newborn underwent to a special training and all of them were able to meet the high requirements of this work. The surgery itself was without complications. The newborn was absolutely sterile up to the age of 1 month; afterwards the infant was gradually colonized with selected strains of bacteria and thus prepared for conventialization. In the course of this work further possibilities of application of gnotobiological techniques in pediatrics were proposed (e.g. care of premature, high-risk neonates).
The incidence of bacteremia in a group of well children undergoing dental extraction of both normal and abscessed teeth was determined. Blood samples were obtained from each child before and immediately after dental instrumentation and then cultured aerobically and anaerobically. Eleven of 36 (30%) of the postextraction cultures were positive, and Streptococcus viridans grew from all of them. Bacteremia was more common after the extraction of diseased teeth, and there was no relationship between bacteremia and the number or species of teeth removed.
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