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Biomedical subjects

R Pabst

Publications and source records attributed to R Pabst.

At least 253 records · Page 14Linked to original sources
PubMed1981

The route of migration of lymphocytes from blood to spleen and mesenteric lymph nodes in the pig.

Porcine peripheral blood lymphocytes were labelled with tritiated uridine in vitro and transfused into normal young pigs. Serial biopsies were taken from the spleen and mesenteric lymph nodes, and the localization of labelled lymphocytes determined on autoradiographs. Four to five hours after cell infusion samples of Peyer's patches, tonsils and small intestine were taken and the labelled lymphocytes classified by their localization in different organ compartments. In spleens most labelled cells were found in the red pulp and about 30% in the marginal zone. Within 4 to 5 h there was a constant increase in labelled lymphocytes in the compartment of the white pulp with more cells localized in the periarteriolar lymphatic sheath than in the corona. In lymph nodes about two thirds of all labelled cells were seen in the wall of high endothelial venules 15 min after cell infusion. Labelled cells then decreased in the vessel wall, but, at the same time, increased in the neighbourhood of these vessels and other parts of the paracortex. After 5 h about 10% of labelled lymphocytes had already migrated into the corona. In tonsils and Peyer's patches a comparable distribution of labelled cells was found in the organ compartments. The kinetics and the route of migration in the spleen and lymph nodes are therefore comparable to data for other species, despite the peculiar structure of pig lymph nodes and the paucity of lymphocytes in efferent lymphatics in pigs.

Animals↗
PubMed1981

Proliferation of human lymphoid cells. Lymphocytopoiesis and cell cycle parameters in isolated perfused human spleens.

Parameters of the cell cycle of lymphoid cells and the rate of production of small lymphocytes and mature plasma cells were estimated in human spleens. 12 normal and 1 enlarged spleen with lymphatic hyperplasia were labelled either by a pulse or continuously with 3H-TdR-thymidine during normothermic perfusion of the isolated spleens. Biopsies of splenic tissue were taken at different intervals and evaluated autoradiographically. The mean initial labelling index of immunoblasts was 73% and for plasmoblasts 52%. The labelling index for small lymphocytes and mature plasma cells increased initially from 0% to 1%, and up to 25% respectively after 14 h. The duration of the S-phase, as determined by double labelling, was 8.26 h for lymphoid blasts. Data from the percentage labelled mitosis curve resulted in a minimal tG2 of about 1 h and tG2 + tM of about 4 h. The estimated generation time was about 11.5 h. The results found on the hyperplastic spleen were comparable to those on the normal spleen.

Adult↗
PubMed1981

The cellular reaction in glomeruli of rats with anti-glomerular basement membrane nephritis.

This work examines the cellular reaction in glomeruli of rats with an acute form of anti-glomerular basement membrane (GBM) nephritis. After intravenous injection of rabbit-derived anti-GBM serum, heterologous and, later, autologous IgG fixed to the glomerular capillary loops. From day 1 to 11 of nephritis, glomerular hypercellularity was not appreciable or modest by qualitative histology, whereas morphometric evaluation revealed mild but significant increases of glomerular cell counts as compared to untreated controls. Histoautoradiographic studies of renal tissue 2 h after pulse administration of 3H-thymidine served to determine the proportion of glomerular cells which synthesized DNA, indicating forthcoming cell division. The mean labeling index (LI) of epithelial cells of Bowman's capsule was 1.8% in controls, rose 4- to 5-fold on the first day of nephritis and fell gradually from day 2 to 11. LI to tuft cells was 1.9% in controls, peaked on day 4, and fell thereafter. Histochemical staining for nonspecific esterase, a marker of monocytes and macrophages, revealed that glomeruli of normal rats contain very few stained cells (mean: 0.2/tuft section). In the course of nephritis, a gradual increase of esterase-positive cells took place in glomeruli which reached a plateau on day 4 (mean: 5.5/tuft section), indicating an influx of migrating monocytes. It is concluded that the injury of this model of anti-GBM nephritis involves markedly enhanced proliferation of intrinsic glomerular cells associated with infiltration of monocytes. Such a prominent cellular response is revealed by the applied quantitative methods in the absence of histologically impressive glomerular hypercellularity.

Animals↗
PubMed1981

Classification of lymphocytes recirculating in the spleen.

After washing out remaining blood cells using cold perfusate, pig spleens were connected to a closed-circuit normothermic perfusion system. Recirculating lymphocytes migrated out and rapidly established an equilibrium with the splenic extravascular lymphoid tissues. Comparison of the subpopulations among these lymphocytes with those in the blood at time of removal of the spleen, showed the absence of Null cells and reduced numbers of weakly E-rosetting cells among splenic emigrants. The proportion of other B- and T-cell subpopulations were increased in a way which might be explained by non-recirculation of these two subpopulations. Autologous blood lymphocytes labelled with fluorescein isothiocyanate and introduced into spleen perfusions rapidly established equilibrium (approximately 15%-25%, well within 1 hr) and at the end of perfusion were concentrated in the marginal zones. The fluorescent lymphocytes remaining in the perfusate showed a marked enrichment of Null cells suggesting that these cells do not home to splenic extravascular lymphoid tissues in agreement with the hypothesis that Null cells are absent from splenic emigrants because they are nonrecirculating cells.

Animals↗
PubMed1981

In vivo labelling of the spleen and mesenteric lymph nodes with fluorescein isothiocyanate for lymphocyte migration studies.

Lymphocytes in normal young pigs were labelled in vivo with fluorescein isothiocyanate in the spleen using an extracorporeal perfusion system and in mesenteric lymph nodes by direct injection into the nodes. Labelled lymphocytes leave the spleen at a high rate via the splenic vein and migrate to different lymphoid organs. Emigrants from mesenteric lymph nodes left the nodes more slowly and revealed a different homing pattern. Evidence is presented that a considerable number of lymphocytes from the parenchyma leave the nodes via the vein and not by the classical route of recirculating lymphocytes via the efferent lymphatics. Fluorescein labelling of lymphocytes in their normal micro-environment is a suitable method for lymphocyte migration studies.

Animals↗
PubMed1980

Regeneration of heterotopically transplanted autologous splenic tissue.

Normal young pigs were splenectomized and thin slices of autologous splenic tissue grafted in pouches of the large omentum and underneath the fascia of the abdominal muscles. The regeneration of the transplanted splenic fragments was studied histologically. Within the first few days, the grafts underwent almost complete necrosis. After 14 days no signs of regeneration could be seen. All typical structures of splenic tissue could be found after 3 months but the red and white pulp were populated to a lesser extent than normal with lymphoid cells. After 6 months and 12 days after i.v. injection of sheep red blood cells, the number of follicles increased dramatically and all the morphological signs of an immune response could be seen. After heterotopic transplantation in young pigs splenic fragments regenerate to small splenules of normal appearance. The regeneration is less rapid and results in smaller masses of tissue than in rodents.

Animals↗
PubMed1980

Perfusion of isolated human spleens.

Twelve normal human spleens were perfused in vitro for 17 h at normothermia. The histological structure was well preserved. Splenic imprints showed a normal cellular pattern, mitoses, and labelled lymphoid cells after 3H-thymidine labelling. Metabolic parameters were comparable to in vivo data of human spleens. The perfusion system can preserve the structure and function of human spleens in vitro.

Humans↗
PubMed1980

Selective labelling of lymphoid tissues by extracorporeal perfusion.

A method for selective labelling of lymphoid tissues by means of an extracorporeal perfusion system is described. The applicability of this technique was tested by local labelling of a part of the small intestine with its mesenteric lymph nodes, spleen and bone marrow in normal young pits. Tritiated thymidine was added to the perfusate and the selectivity of the labelling procedure tested by scintillation counting of serum samples, of specimens of lymphoid tissues and by autoradiography. There was only negligible spillover of the isotope and the perfused organs were well preserved.

Animals↗
PubMed1979

Evaluation of lymphocyte production in mesenteric lymph nodes.

In normal young pigs two labeling procedures were evaluated to study the production of lymphocytes in mesenteric lymph nodes. Tritiated thymidine was injected either into the superior mesenteric artery or directly into the lymph nodes. There was a high rate of lymphocyte production and a considerable export of newly-formed small lymphocytes. The distribution to lymphoid organs and the appearance of labeled lymphocytes in the blood were comparable after both techniques. The intranodal labeling resulted in a more selective labeling and thus was found to be the superior method for quantitative studies.

Animals↗
PubMed1979

Selective labeling of mesenteric lymph nodes: cell production and emigration of newly formed lymphocytes to other organs.

Lymphocyte production by mesenteric lymph nodes of normal young pigs was studied by intranodal injections of either tritiated thymidine or tritiated deoxycytidine as DNA precursors. One or two days after selective labeling of the mesenteric lymph nodes the relative and absolute number of lymphocytes derived from mesenteric lymph nodes were determined autoradiographically in the following organs: mesenteric, cervical and inguinal lymph nodes, spleen, thymus, bone marrow, Peyer's patches, tonsil, different regions of the gut, lung and liver. The overall cell production of mesenteric lymph nodes, as derived from the sum of all labeled cells one day after labeling, was estimated to be about 7 X 10(9) lymphocytes. Up to 40% of all newly formed lymphocytes had already left the lymph nodes within one day and were found in all organs studied. There was a preferential homing to the mucosa of the small intestine, but a considerable number migrated to the spleen and even to the thymus and bone marrow. In lymphoid organs all labeled cells were small and medium-sized lymphocytes one and two days after labeling. In cervical lymph nodes, spleen, tonsil and Peyer's patches the relative distribution to T and B cell areas was determined. There was an obvious preference of newly formed lymph node cells to home to T cell areas. The differences of labeling between thymidine or deoxycytidine were surprisingly low.

Animals↗
PubMed1979

Is the low fertility rate after vasovasostomy caused by nerve resection during vasectomy?

Cross-sections of human spermatic cords and vasectomy specimens were prepared and the number and cross-sectional area of nerves were determined. On average, about one-half of all nerves in the near neighborhood of the vas deferens were resected during vasectomy. The total cross-sectional area of the nerves along the vasectomy specimens amounted to about one-half of the total area in the spermatic cord samples. The data support the hypothesis that removing nerves to the vas deferens during vasectomy could result in poor functional results after vasovasostomy, i.e., that powerful contraction of the proximal vas deferens and epididymis could be lacking.

Denervation↗
PubMed1978

Migration pattern of splenic lymphocytes after local labelling of the pig spleen with 3H-cytidine.

In normal young pigs splenic lymphocytes were selectively labelled by injecting tritiated cytidine into a splenic artery. 10 h later several lymphoid and non-lymphoid organs were investigated for spleen-derived lymphocytes by autoradiography. The relative and absolute organ distribution of the labelled cells was determined. Labelled lymphocytes appeared rapidly in the peripheral blood reaching a mean labelling index of 4.8%. More splenic lymphocytes were found in thymus dependent areas than in thymus independent areas of lymphoid organs. Nearly 40% of all emigrated lymphocytes homed to lymph nodes and only about 1% in the thymus. A surprisingly high number of splenic lymphocytes were located in the bone marrow and the lung.

Animals↗