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Biomedical subjects

A O Anderson

Publications and source records attributed to A O Anderson.

51 records · Page 3Linked to original sources
PubMed1985

Reovirus serotype 1 intestinal infection: a novel replicative cycle with ileal disease.

After oral inoculation, reovirus serotype 1 strain Lang was shown to specifically infect the epithelial cells of the ileum, while sparing the epithelial cells in the duodenum, jejunum, and colon. The initial site of replication was localized in cells of the crypts of Lieberkühn adjacent to Peyer's patches. Virus was subsequently found by immunoperoxidase staining in cells migrating up the crypt-villus complex throughout the ileum. The severity of the pathological changes in the ileum was proportional to the concentration of the viral inoculum. This site-specific infection of the ileum by reovirus may provide a model for diseases that are restricted to specific sites in the intestine.

Animals↗
PubMed1984

The immunohistology of the thymus in myasthenia gravis.

We have investigated cell subpopulations in frozen sections of thymus tissue obtained from myasthenic (MG) and control subjects. With the use of an avidin-biotin immunoperoxidase system with monoclonal antibodies, the following cell surface antigens were studied on frozen sections (12 MG and 3 control thymus); T11, T4, T6, T8, IgM, IgD, and Ia. The pattern of T cell phenotypes in MG thymus is similar to that of normal control thymus when examined by immunohistologic techniques. MG cortical thymocytes are virtually all T11+, T4+, T8+, and T6+. In the medulla, at least 45% of thymocytes are T11+, with T4+ cells predominating over T8+ cells. Approximately 10% of medullary thymocytes are T6+. Scattered medullary cells expressing surface IgM and IgD are identified in both MG and normal thymuses. However, unlike the normal thymus, the MG thymus has numerous secondary follicles containing IgM- and IgD-bearing cells. This finding supports the hypothesis that the MG thymus microenvironment is aberrant. The Ia antigen is found in similar tissue section localization patterns in MG and control thymus. Ultramicroscopic studies show the Ia antigen predominantly on epithelial and interdigitating dendritic cells. By immunoperoxidase techniques, numerous keratin-positive cells are demonstrated in MG and control thymus. This suggests that thymic epithelial cells, like epithelial cells elsewhere, contain keratin. Because these data differ in degree from our previous findings in suspensions of MG thymocytes, this study emphasizes the importance of examining tissue sections as well as cell suspensions when one is studying lymphocyte surface markers.

Adult↗
PubMed1983

Opsonization of alphaviruses in hamsters.

Immune elimination of alphaviruses in immunized hamsters appears to involve formation of virus/antibody aggregates which are subsequently cleared from the circulation by cells of the reticuloendothelial system (RES). Virulent strains of Venezuelan (VEE) and Western equine encephalitis (WEE) viruses which were cleared slowly from the circulation of nonimmune hamsters, were cleared rapidly when inoculated into the blood of immunized hamsters. Likewise, when these viruses were mixed with specific hamster immune serum prior to inoculation, they were efficiently cleared from the circulation of nonimmune hamsters. Virus, mixed with specific immune serum, or inoculated into immunized hamsters, formed virus/antibody aggregates, as demonstrated by density gradient centrifugation, filtration through polycarbonate membranes, precipitation with Staphylococcus protein A, and electron microscopy. Cleared virus was concentrated primarily in liver and spleen, as confirmed by autoradiography. Immune clearance of virulent VEE was demonstrable within 5 to 6 days following immunization of hamsters with live attenuated VEE vaccine, strain TC-83. In these hamsters, a close association was established between formation of virus/antibody aggregates, rapid clearance, and survival of challenged hamsters. Adsorption of virus to hamster macrophages in culture was enhanced by immune serum in the presence of complement. These results are compatible with the hypothesis that immune clearance of virus in the intact hamster involves a complement-dependent interaction of virus/antibody complexes with cells which possess Fc and complement receptors. The clearance of immune complexes by the RES serves to amplify the protective effect of neutralizing antibody alone.

Adsorption↗
PubMed1983

Influence of islet and bone marrow transplantation on the diabetes and immunodeficiency of BB rats.

The results of islet transplantation in spontaneous autoimmune diabetes of BB rats were studied to determine whether this disease process might damage the transplanted islet tissue. Since BB rats are not genetically uniform, syngenetic grafts could not be used; therefore, allograft rejection was prevented by rendering BB rats immunologically tolerant of WF transplantation antigens by neonatal inoculation with bone marrow cells. Despite the resultant tolerant state, which permitted successful engraftment of WF skin allografts, the transplanted islets ameliorated the spontaneous diabetes of BB rats only briefly before they were destroyed by immune insulitis. BB rats from the diabetic stock were found to suffer from abnormalities in T lymphocytes and their subsets as well as defective immune response patterns. When analyzed with monoclonal antibodies specific for rat lymphocyte markers, BB rats of the diabetic stock were found to be lymphocytopenic. There was a reduction in helper T cells and a more severe deficit in the suppressor/cytotoxic subset. BB rats that were inoculated neonatally with bone marrow from normal donors were found to have a strikingly reduced incidence of diabetes. Moreover, the T cell functional, numerical, and microenvironmental defects that were present in noninoculated BB rats were restored in marrow-inoculated BB rats, findings possibly related to the decreased incidence of diabetes.

Animals↗
PubMed1981

Prevention of diabetes in rats by bone marrow transplantation.

Hyperglycemia, hypoinsulinemia and ketonemia often develop abruptly in previously normal young "BB" rats. The syndrome mimics human juvenile diabetes closely and is, thus, appropriate for assessing pancreatic transplantation. Transplantation of islet cells from closely histocompatible Wistar Furth (WF) donor resulted in permanent normoglycemia when immunosuppression with ALS was given. However, when islet cells from nondiabetic "BB" donors were transplanted to nonimmunosuppressed diabetic "BB" recipients, only transient normoglycemia followed. Transplantation of WF islets cells also failed in diabetic "BB" rats which were tolerant of WF antigens, again suggesting destruction of transplanted islet cells by the original disease process-possibly autoimmunity. Evidence for autoimmunity was strengthened by the finding that newly diabetic "BB" rats could be rendered normoglycemic by immunosuppression. Since genetic susceptibility to spontaneous autoimmune diabetes is unique to some members of the "BB" stock, an attempt was made to alter their vulnerability by modifying their cellular immune system. Accordingly, 50 million bone marrow cells from WF donors were inoculated into half the newborn members of "BB" litters, leaving the littermates as unmodified controls. Most bone marrow recipients were protected, only four of 37 (10.8%) ever becoming diabetic, while the incidence of diabetes in noninoculated littermates was 22 of 39 (56.4%). The ultimate goal in human diabetes, which also seems very likely to be an autoimmune disease, may not be replacement of destroyed islet cells but identification of potentially susceptible children and prevention of islet destruction by immunologic manipulation.

Animals↗
PubMed1979

Basic mechanisms of lymphocyte recirculation in Lewis rats.

Lymphocyte locomotion in vivo depends upon an intact network of subplasmalemmal contractile microfilaments which are linked through the membrane to surface receptors, and the distribution and stabilization of recognition receptors may be controlled by microtubules and/or 10-nm filaments in the cytoplasm. The differential effects of cytochalasin-A and colchicine on lymphocyte homing and locomotion have proven useful in dissecting the subcellular events underlying the process of lymphocyte recirculation.

Animals↗
PubMed1977

Heparin-induced coagulopathy.

Intravenous heparin, at doses of 3.0 U./gm of body weight, produced an intravascular coagulopathy in rats which was manifested by intestinal tract hemorrhage, a reduction in plasma fibrinogen concentration, a rise in fibrinogen-fibrin degradation products, and the absence of a rise in platelet count noted in the control animals. This coagulopathy could not be produced by conventional anticoagulant doses of heparin or the injection of large doses of heparin in the presence of protamine sulfate. Specific studies excluded hypoxemia, metabolic acidosis, and endotoxemia as possible etiologic factors. The coagulation abnormalities observed in this study differ from those produced by injection of other polyanionic substances but their precise pathogenesis is still uncertain.

Animals↗
PubMed1976

Specialized structure and metabolic activities of high endothelial venules in rat lymphatic tissues.

Microscopic, histochemical and ultrastructural techniques were used to define characteristics of high endothelial venules (HEV) in rat lymphatic tissues. This endothelium contained acetyl esterase and acid hydrolase activities which were not altered by lymphocyte depletion. No immunoglobulins were detected on luminal surfaces of HEV by fluorescent antibody staining. Only minor structural differences were seen between HEV within lymph nodes and Peyer's patches. At both sites, high endothelial cells were linked together by macular junctional complexes and interlocking basal foot processes. Endothelial cell cytoplasm moulded about surfaces of lymphocytes migrating through the venular wall, and flocculant deposits of basement membrane formed over lymphocytes penetrating the basal lamina. The endothelium was ensheathed by three to five layers of overlapping reticular cell plates and connective tissue. Each plate was linked to the reticular meshwork of the node by collagen bundles and anchoring filaments which inserted into the plate's external limiting membrane. This permitted individual paltes to separate or approximate each other as tissue and intravascular pressure varied, and lymphocytes moved across the sheath by insinuating themselves into gaps between overlapping plates. This composite structure of the HEV wall appeared to facilitate lymphocyte entry into the node and minimized vascular leakge.

Animals↗
PubMed1976

Lymphocyte emigration from high endothelial venules in rat lymph nodes.

Sequential events during lymphocyte emigration from high endothelial venuses (HEV) were studied by scanning and transmission electron microscopy combined with regional perfusion techniques. The results indicate that blood lymphocytes selectively adhere to HEV surfaces through microvilli which attach to shallow pits on the luminal surfaces of high endothelial cells. These intercellular contact points resist hydrodynamic and osmotic shearing forces, but can be disrupted by treatments which remove endothelial glycocalyx, hydrolyse lymphocyte surface glycoproteins, or chelate divalent cations. After this initial attachment phase, lymphocytes enter apical clefts between endothelial cells where they assume a motile configuration characterized by loss of microvilli and formation of irregular surface folds. Intramural lymphocytes adhere to adjacent endothelial cells through macular and villous contacts. Fibrillar electron-dense material traverses the 15-20 nm gap at these points of adhesion. Microtubules and microfilaments are also seen around areas of cytoplasmic constriction in these motile lymphocytes. The migrating lymphocytes show cytoplasmic polarity which is oriented in the direction of movement as they pass through extracellular spaces in the venular wall and cross successive laminations in the perivascular sheath to enter the node. Since these lymphocytes enter channels between endothelial cells which are stained by intralymphatic injections with horseradish peroxidase, it is suggested that their entry into the node depends upon migration along a chemotactic gradient.

Animals↗
PubMed1975

Microvascular changes in lymph nodes draining skin allografts.

Histological, histochemical, ultrastructural, and radiolabeling characteristics of the microvasculature in regional nodes draining skin allograft sites are described. From 12 to 48 hours after grafting, these nodes show increased vascular permeability and altered lymphocyte traffic pattern. The rapid rise in lymphocyte migration indices and the apparent plugging of intermediate sinuses by lymphocytes suggest that both increased entry and decreased egress of recirculating cells contribute in "lymphocyte trapping." This is followed by redistribution of cortical capillary arcades as existing germinal centers dissolve and proliferating lymphocytes infiltrate the cortex. Normal microvascular patterns reappeared at 7 to 14 days as primary and secondary nodules form in the enlarged nodes. Increased length and arborization of high endothelial venules resulted from focal proliferation of endothelial cells in transition zones from high to low endothelium. In stimulated nodes, high endothelial cells exhibit increased cytoplasmic basophilia and acid hydrolase activities which correlate with the appearance of numerous polyribosomes, RER cisternae, and lysosomes in their cytoplasm. These "activated" endothelial cells phagocytose microthrombi within venular lumens.

Animals↗
PubMed1975

Studies on the structure and permeability of the microvasculature in normal rat lymph nodes.

The structure and permeability of the microvasculature in normal rat lymph nodes was studied by regional perfusion techniques. The results indicated that characteristic vascular units supplied each cortical lobule of lymphatic tissue. Numerous arteriovenous communications and venous sphincters innervated by unmyelinated nerve fibers were found in this vascular bed. These specialized vascular structures permitted regional control of blood flow through high endothelial venules. Lymphocytes migrated across these venular walls by moving through intercellular spaces in the endothelium and between gaps in the laminated, reticular sheath. No direct anastomoses between blood vessels and lymphatics were seen, but tracer studies with horseradish peroxidase suggested that functional lymph node-venous communications were present in the walls of high endothelial venules.

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