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F MILLER

Publications and source records attributed to F MILLER.

At least 19 recordsLinked to original sources
PubMed1964

LYTIC ACTIVITIES IN RENAL PROTEIN ABSORPTION DROPLETS. AN ELECTRON MICROSCOPICAL CYTOCHEMICAL STUDY.

The digestive cycle following reabsorption of hemoglobin by cells of the proximal convoluted tubules in mouse kidney and the uptake of ferritin by glomerular mesangial cells in the kidney of normal and nephrotic rats were investigated by electron microscopical histochemical procedures. Mouse kidneys, sampled at closely spaced time points between 1 to 48 hours after intraperitoneal injection of hemoglobin, and rat (normal and nephrotic) kidneys, sampled at 30 minutes, 2 hours, and 48 hours after intravenous injection of ferritin, were fixed in glutaraldehyde, cut at 50 micro on a freezing microtome, incubated for acid phosphatase and thiolacetate-esterase, and postfixed in OsO(4). Satisfactory preservation of fine structure permitted the localization of the enzymatic reaction products on cell structures involved in uptake and digestion of exogenous proteins. The latter were identified either by their density (hemoglobin) or their molecular structure (ferritin). It was found that lysosomal enzymic activities and incorporated exogenous proteins occur together in the same membrane-bounded structures. In the cells of the proximal convolution, lytic activities become demonstrable within 1 hour after hemoglobin injection, appear first in apical vacuoles filled with hemoglobin, and persist in fully formed protein absorption droplets. At the end of the lytic cycle ( approximately 48 hours post injection), the cells have an increased population of polymorphic bodies which exhibit lytic activities. In smaller numbers, identical bodies occur in controls. It is concluded that they represent remnants of previous digestive events. The means by which the resorptive vacuoles acquire hydrolytic activities remain unknown. Fusion of newly formed vacuoles with residual bodies was not seen, and hemoglobin incorporation into such bodies was only occasionally encountered. Acid phosphatase activity was found sometimes in the Golgi complex, but enzyme transport from the complex to the resorbing vacuoles could not be established. Autolytic vacuoles containing mitochondria or mitochondrial remnants were frequently found during the early stages of hemoglobin resorption, but no definite conclusions about the mechanism involved in the segregation of endogenous material were obtained. In nephrotic rats ferritin was segregated in membrane-bounded bodies mainly in the mesangial cells and to a lesser extent in epithelial and endothelial cells. Most of these sites were marked by the reaction products of acid phosphatase and organophosphorus-resistant esterase and therefore identified as lysosomes connected with the digestion of incorporated exogenous proteins.

Acid Phosphatase↗
PubMed1961

Lipoprotein granules in the cortical collecting tubules of mouse kidney.

The light and, to a lesser extent, the dark cells of the cortical collecting tubules in mouse kidney contain a great number of granules which according to histochemical tests are composed of phospholipids and proteins. These granules are bounded by a triple-layered membrane measuring approximately 75 A across, and contain one or several crystals with a hexagonal or square lattice. These crystals are built up of rod-shaped units, which appear dense after osmium fixation, measure about 48 A in diameter, and are separated by a light interspace of similar dimensions. The mean center-to-center distance of the rods is about 96 A. The structure is explained as a lipoprotein crystallized within a membrane-bounded vacuole. No relationship between these granules and mitochondria was found. The physiological significance of the granules remains unknown.

Animals↗
PubMed1960

The pathologic effects of intravenously administered soluble antigen-antibody complexes. I. Passive serum sickness in mice.

The intravenous administration to mice of soluble antigen-antibody complexes in antigen excess resulted in a high incidence of glomerulonephritis and less frequently in endocarditis or arteritis. These lesions are present within 48 hours of the first of 3 injections and disappear within 2 weeks. The same pathological changes were produced with complexes prepared from either rabbit or chicken antibody. In the case of rabbit antibody, the severity of the glomerulonephritis was greater with the ovalbumin antiovalbumin system than with the BSA system. Anaphylaxis regularly occurred in mice given complexes prepared from rabbit antibody, but was not seen following administration of complexes prepared from chicken antibody. Pretreatment with cortisone diminished the severity of the glomerulo-nephritis and resulted in accumulation of amorphous, eosinophilic material within glomerular capillaries in mice injected with antigen-antibody complexes. The rabbit antibody used in these experiments failed to sensitize guinea pig skin to passive cutaneous anaphylaxis when injected in the form of soluble complexes. This indicates that these complexes do not dissociate to a detectable extent in vivo and thus favors the interpretation that complexes localize as such in the sites where tissue damage occurs. Chicken anti-mouse erythrocyte antibody produced hemolysis of mouse red cells in the presence of mouse complement. In contrast to a similar rabbit anti-serum, the hemolytic activity of the chicken antibody with mouse complement was very slight. This suggests that complement does not play an important role in the pathogenesis of these experimental lesions.

Animals↗
PubMed1960

Hemoglobin absorption by the cells of the proximal convoluted tubule in mouse kidney.

The formation of protein absorption droplets in the cells of the proximal convolution was studied in mouse kidney. Ox hemoglobin was administered intraperitoneally and kidney specimens were collected at intervals of 30 minutes to 4 days after injection. In the lumen of the nephron, hemoglobin was concentrated to an opaque mass whose relations with the brush border and the epithelium could be easily followed. It was found that hemoglobin passes through the brush border in between the microvilli, enters the channels of tubular invaginations at the bases of the brush border, and is transported in bulk into vacuoles in the intermediate cell zone. These vacuoles increase in size and are transformed through further concentration into dense absorption droplets. Using the opaque hemoglobin content of the nephron as a tracer, functional continuity of the system of the tubular invaginations with the lumen on one side and the vacuoles on the other was demonstrated. Mitochondria lie closely apposed to vacuoles and droplets, but are not primarily involved in droplet formation. 15 hours after injection and later, ferritin and systems of layered membranes become visible in the droplets as their density decreases. These membranes are interpreted as lipoprotein membranes; similar membranes are found in the lumen of the tubuli. It is suggested that phospholipids enter into the vacuoles together with hemoglobin from the tubular lumen and form membrane systems of lipoproteins in the droplets. At 3 to 4 days the droplets contain aggregates of ferritin, and the iron reaction becomes positive in the tubule cells. No significant changes were found in the Golgi apparatus or in the microbodies during hemoglobin absorption. At all time points investigated, the terminal bars seal the intercellular spaces against penetration by hemoglobin in the proximal and distal convolutions and in the collecting ducts.

Animals↗