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R S Cotran

Publications and source records attributed to R S Cotran.

At least 109 records · Page 6Linked to original sources
PubMed1970

An ultrastructural study of glomerular permeability using catalase and peroxidase as tracer proteins.

Mice were injected intravenously with beef liver catalase (mol wt 240,000) and very small doses of horseradish peroxidase (mol wt 40,000) and the site of localization of these enzymes in the kidney was studied by ultrastructural cytochemistry. 1 min after injection, catalase was present in glomerular capillary lumina and there was minimal permeation of the basement membrane. After 5-180 min, staining of the basement membrane increased progressively but was usually less than that in capillary lumina. At all time intervals the inner (sub-endothelial) layer of the basement membrane contained more reaction product than the lamina densa and the outer (subepithelial) layer. Catalase permeated the entire thickness of the basement membrane and extended up to the slit pore but not beyond the level of the slit diaphragm and was not seen in the urinary space or tubular lumina. Horseradish peroxidase permeated the whole thickness of the basement membrane within 2 min after injection; however, gradients of staining from the inner to outer layers of the basement membrane were frequently seen. The findings with both enzymes indicate that (a) the basement membrane restricts the passage of proteins over a wide range of molecular size with increasing impediment for larger molecules and (b) the slit pore functions as an additional barrier for molecules that cross the basement membrane.

Animals↗
PubMed1970

An ultrastructural study of glomerular permeability in aminonucleoside nephrosis using catalase as a tracer protein.

Beef liver catalase (mol wt 240,000) was injected intravenously into normal rats and rats made nephrotic with aminonucleoside of puromycin. The localization of the tracer in the kidneys was then studied by ultrastructural cytochemistry, 3 min-12 hr after injection. Passage of catalase into the urinary space in normal rats was restricted by the basement membrane and by the epithelial slit pore. Nephrotic glomeruli showed extensive fusion of foot processes and formation of pockets and vacuoles in the fused epithelium; within 3 min after injection, catalase appeared in basal pockets, epithelial vacuoles, and the urinary space. Residual slit pores and close junctions in fused epithelium were impermeable to catalase. These studies indicate that alteration of the epithelial cells and basement membrane is responsible for protein leakage in aminonucleoside nephrosis.

Animals↗
PubMed1970

The interaction between human monocytes and red cells. Binding characteristics.

Red cells coated with IgG globulin were bound firmly to human mononuclear cells and formed rosettes. Rosette formation occurred when red cells were coated with IgG attached either immunologically (anti-D, anti-penicillin, or Donath-Landsteiner antibodies) or nonimmunologically with chromic chloride; no attachment was observed with cells coated with albumin. Rosette formation was blocked by pretreatment of white cells with sulfhydryl-binding reagents. Metabolic inhibitors did not prevent red cell adherence. White cells of other primates demonstrated a high degree of species specificity. Ultrastructural studies showed that the predominant leukocytes involved in rosette formation were monocytes, but some cells with characteristics of lymphocytes also formed rosettes. Considerable interdigitation of cell surfaces occurred at attachment sites and bound red cells appeared deformed. Thus, these studies confirm the presence of specific surface receptors for IgG on human monocytes and suggest that such receptors may provide a mechanism by which large numbers of red cells are eventually destroyed.

Antigen-Antibody Reactions↗
PubMed1969

Glomerular permeability. Ultrastructural studies in experimental nephrosis using horseradish peroxidase as a tracer.

Wistar/Furth rats were made nephrotic by daily administration of amino-nucleoside of puromycin, and the ultrastructural localization of horseradish peroxidase (mol wt 40,000) in the renal glomerulus was studied from 1 min to 20 hr after intravenous injection of the tracer. In control rats, peroxidase permeated the endothelial fenestrae, the basement membrane, and the epithelial slits, and was present in tubular lumina. Nephrotic glomeruli showed relatively normal basement membranes, extensive fusion of foot processes with formation of "close" intercellular junctions, and large vacuoles and pockets in epithelial cells. On serial sections some of the epithelial vacuoles communicated on one side with the extracellular space overlying basement membrane, and on the other side with the urinary space. In nephrotic animals, peroxidase permeated the basement membrane and the close junctions, and was present in many of the vacuoles and pockets as early as 1 min after injection. Only small numbers of peroxidase-positive vacuoles remained in. epithelial cells 1 hr or more after injection of the tracer. It is suggested that the epithelial pockets and vacuoles form pathways across which leaking proteins can be transferred across the epithelium into the urinary space. Epithelial vacuoles may also be absorption droplets designed to "conserve" leaking proteins, but this function was not prominent in our experiments with peroxidase.

Animals↗
PubMed1969

The entry of granule-associated peroxidase into the phagocytic vacuoles of eosinophils.

The ultrastructural localization of peroxidase was studied in guinea pig eosinophils which had phagocytized zymosan or Escherichia coli. After phagocytosis, the membrane of the granule was joined to the membrane of the phagocytic vacuole, and the enzyme, which is ordinarily restricted to the matrix of the granule, was seen in the vacuole surrounding the ingested particle.

Animals↗
PubMed1969

Lysosomal and ultrastructural changes in human "toxic" neutrophils during bacterial infection.

"Toxic" neutrophils from humans with severe bacterial infections, identified by the presence of Döhle bodies, "toxic" granules, and vacuoles were shown to differ from normal neutrophils both in ultrastructure and in lysosome activity. Döhle bodies were identified as lamellar aggregates of rough endoplasmic reticulum. Toxic granules corresponded to the azurophilic granules usually identified by Romanowsky stains only in neutrophil precursors. By electron microscopy such granules were large, electron-dense, and peroxidase positive; they could usually be distinguished from the smaller, less dense, "specific" granules also present in control neutrophils, but in the latter they became visible by light microscopy only after prolonged staining or following fixation with glutaraldehyde. These observations suggest that toxic granules represent an abnormal staining reaction of the large dense granules in the toxic cells, and not phagocytized material, newly formed abnormal granules or autophagic bodies. Alkaline phosphatase activity was significantly greater in toxic neutrophils than in normal ones; 80% of the activity of both was located in the lysosome fraction. Beta glucuronidase was normal. Total acid phosphatase was normal, but the percentage located in the nonlysosome fraction of toxic neutrophils was increased, suggesting that lysosomes were "labilized." Formation of neutral red vacuoles in supravitally stained preparations, an index of lysosome activity, occurred more rapidly in toxic neutrophils. This reaction paralleled degranulation and the formation of clear vacuoles in unstained wet mounts and could be blocked by colchicine, a lysosome stabilizer, or enhanced by procedures which activate lysosomes. "Autophagic" vacuoles were observed by electron microscopy in some toxic neutrophils. These observations are discussed in relation to the concept that the "toxic" neutrophils in severe bacterial infection reflect cellular immaturity and/or stimulation or degeneration.

Alkaline Phosphatase↗
PubMed1968

Ultrastructural studies on the permeability of the mesothelium to horseradish peroxidase.

Peritoneal mesothelium was exposed for 2-60 min to solutions of horseradish peroxidase by incubation in vitro, or after intraperitoneal injection in vivo. Peroxidase was localized, with the electron microscope in the intercellular clefts of the mesothelium, often along their entire lengths, in vesicles adjoining or contiguous with the clefts, and along the peritoneal and basal surfaces of the cell, and also in intracytoplasmic vacuoles. The intercellular junctions of peroxidase-treated mesothelium did not differ from those of controls: open and closed junctions were present in both groups. Intercellular localization was also obtained when the mesothelium was exposed to peroxidase during or after fixation. Although intracellular absorption of peroxidase and its incorporation into larger vacuoles were observed, there was no clearcut evidence of vesicular transport across the mesothelium in these experiments. These findings are consistent with physiologic data which postulate that mesothelial transport can be accounted for, at least in part, by passive diffusion through a system of pores, and they suggest that these pores are located in the intercellular clefts.

Animals↗