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Biomedical subjects

R Pabst

Publications and source records attributed to R Pabst.

At least 271 records · Page 15Linked to original sources
PubMed1977

Relative and absolute numbers of E- and EAC-rosette-forming cells in lymphoid organs.

The percentage of lymphocytes of the blood and lymphoid organs of young pigs were determined by forming rosettes with pretreated sheep red blood cells (AET-rosettes) or with sheep red blood cells coated with antibody and complement (EAC-rosettes). The mean figures for AET-rosettes were 70% for the blood, 93% for the thymus, 78% for lymph-nodes and 68% for the spleen. For EAC-rosettes the numbers were 16%, 0%, 16% and 19% respectively. The absolute numbers of rosette-forming lymphocytes were estimated on the basis of previously determined numbers of lymphoid cells in young pigs. Even by excluding the data for the thymus, there would be about three times more AET-rosette forming lymphocytes than EAC-rosette forming cells in the whole animal. About 11% of all lymphocytes did not show any of these markers. Data on the numbers of "B" and "T" lymphocytes in human lymphoid organs from the literature were summarized and compared to those found in pigs and thus, the absolute numbers for a young adult man estimated.

Animals↗
PubMed1977

Factor VIII coagulant activity and factor VIII-related antigen released from isolated perfused human spleens.

Eight human spleens were perfused for up to 65 h at normothermia and the coagulant Factor VIII activity measured in the perfusate. In addition, in three experiments Factor VIII-related antigen was determined in the perfusate. Although the spleens were pathologically enlarged and the normal structure involved by different diseases, all spleens released Factor VIII coagulant activity and Factor VIII-related antigen. On average the total amount of Factor VIII coagulant activity released was equivalent to that of 3.5 l of human plasma.

Antigens↗
PubMed1977

Rosette formation of pig peripheral blood lymphocytes with sheep red blood cells.

Peripheral blood lymphocytes of normal young pigs formed spontaneous and EAC rosettes with sheep red blood cells. Pretreatment of the SRBC with a sulphydryl reagent increased the percentage of spontaneous rosettes and the number of SRBC bound by the lymphocytes. The influence of an incubation period prior to centrifugation and the duration and temperature of the following incubation were tested for spontaneous and EAC rosettes. The importance is stressed to define the number of bound SRBC to call a lymphocyte a "rosette-forming cell". Rosette formation is interpreted as a quantitative rather than a qualitative marker.

Animals↗
PubMed1976

Comparison of in vitro and in vivo cell cycle parameters of lymphoid cells in pig spleens.

Parameters of the cell cycle of lymphoid cells were estimated by analyzing percent labeled mitoses curves after a 3H-thymidine flash. Either anaesthetized pigs were labeled and multiple biopsies taken from the spleen in vivo or isolated perfused pig spleens were labeled in vitro. The data from in vivo and in vitro experiments were very similar. The mean values for cell cycle parameters were: 20.2 to 20.5 hours for the generation time, about 0.5 to 1 hour for G2, about 1.2 to 1.3 hours for M; about 17 to 16.4 hours for S and about 1.5 to 1.7 hours for G1. The mean grain count halving time of labeled mitoses was in accordance with the measured generation time. The isolated perfused spleen seems to give results equal to in vivo data and could, therefore, be employed as a model for studying cell cycle parameters not only in animal but also in human lymphoid tissue.

Animals↗
PubMed1976

The predominant role of the spleen in lymphocyte recirculation. II. Pre- and postsplenectomy retransfusion studies in young pigs.

Autologous blood lymphocytes from three normal pigs were labelled with 3H-uridine and retransfused before and after splenectomy. Frequent samples for up to 150 min after retransfusion were evaluated autoradiographically to determine the rate of disappearance of labelled lymphocytes from the blood. In one pig retransfusion was performed before and after sham-splenectomy. In all preoperative experiments the pattern of disappearance of labelled lymphocytes was very similar. After a first rapid decline (halving time on average 8 min) a short rise of the labelling index was observed from 10 to 15 min after retransfusion. Then a second more gradual decrease of labelled lymphocytes followed. The mean halving time during this period was less than 32 min. From 60 min onwards the labelling index remained nearly constant. Retransfusions performed 3 days after splenectomy revealed only one nearly constant decline of the labelling index (halving time on average 129 min). After sham-splenectomy the pattern of disappearance was similar to the preoperative experiment. One hour after the end of retransfusion the labelling index had decreased by three-quarters of the initial value in normal pigs and by only one-third in the splenectomized ones. These results indicate that in the pig the total rate of recirculation is at least 4 times faster with the spleen in situ than without the spleen.

Animals↗
PubMed1976

[The influence of the N-mustard derivative "cytostasan" on pregnancy and fetal development in the rat].

This presentation describes the action of Cytostasan, a nitrogen mustard compound of benzimidazole, on reproduction and embryonic development of Wistar rats. Single doses from 20 through 100 mg/kg body weight were given intraperitoneally on the 4th, 7th, 9th, 11th or 13th day post coitum. All test animals were sacrificed on the 20th day of pregnancy. The following parameters served as a base for evaluation: the means of implantation rates, resorption rates, fetal body weights and the number of dead and living fetuses. Malformations were detected by outer inspection for gross anomalies, by means of the razor blade technique for malformations of organs and by alizarin preparations for detecting anomalies of the osseuos skeleton. All results were compared with those of an untreated control group and evaluated by statistical means. Cytostasan exerts embryotoxic and teratogenic effects in appropriate dosage. Notwithstanding the fact of giving high doses (1/2 LD 50) there is no loss of blastocysts before implantation: the number of implantation sites equals that of the control group. The resorption rate increases at all examined days of development after application of 40 mg/kg, but 20 mg/kg exert effects only on days 4, 7, and 11 p. c. There is no action on the number of living fetuses after injection of 20 mg Cytostasan/kg body weight. After application of 40 mg/kg the number of living fetuses decreases especially on the 7th, 9th, and 13th day p. c. There is a dose-dependent stunting: the fetal body weight is not reduced after a dosage of 20 mg/kg, but 40 mg/kg cause a considerable loss of weight during embryogenesis (days 9, 11, 13). It is impossible to induce stunting during blastogenesis (days 4 and 7). The observed patterns of malformation are relatively uniform: kinked tails, omphaloceles, hydronephroses, hydrocephali. Skeletal defects are absent. The results received are compared with other findings on aklylating antitumour drugs.

Abnormalities, Drug-Induced↗
PubMed1975

Quantitative evaluation of the total number and distribution of lymphocytes in young pigs.

In young pigs, the spleen, thymus and all lymph nodes were dissected out and weighed. The relative content of lymphoid cells was determined from histological sections. The number of nucleated cells was evaluated by two different methods: firstly, by measuring the DNA content of samples of lymphoid tissue and dividing by the DNA content of a single nucleus; and, secondly, by counting all lymphoid cells in histological sections of defined volumes of these organs. The number of lymphoid cells in tonsils, gut, bone marrow and lung were determined using histological evaluations and the volumes or weights of these organs. The resulting average number of lymphocytes was 321 times 10 (9) for a pig of 26 kg body weight. The lymphocytes showed the following distribution in lymphoid and non-lymphoid organs: thymus 44%, spleen 9%, mesenteric lymph nodes 17%, cervical lymph nodes 9%, other peripheral lymph nodes 3%, gut-associated lymphocytes 5%, tonsils 2%, bone marrow 5%, blood 3%, lung 0.2% and an estimated figure of 3% for all other tissues.

Animals↗
PubMed1975

The predominant role of the spleen in lymphocyte recirculation. I. Homing of lymphocytes to and release from the isolated perfused pig spleen.

Lymphocyte recirculation through the isolated pig spleen was studied by means of a perfusion system which kept the organ alive for a prolonged period of time. By changing the perfusate to a leucocyte-enriched or cell-free perfusate and taking serial arterial and venous samples, the numbers of lymphocytes which homed to or were released from the spleen were measured. In all experiments more lymphocytes homed than were released per minute. There was no apparent difference when autologous or allogeneic cells were used. The number of lymphocytes released depended on the number of lymphocytes homed previously. During the phase of constant release up to 3-3 X 10(6) lymphocytes were released per gram spleen per minute. From these values it can be extrapolated that up to 270 X 19(9) lymphocytes recirculate through the isolated pig spleen per day. Based on kinetic data from other species it is estimated that in the entire pig a total number of 300-400 X 10(9) lymphocytes recirculate per day. Thus, it can be concluded that the spleen is the most important organ for lymphocyte recirculation in the pig.

Animals↗