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Biomedical subjects

F A Carone

Publications and source records attributed to F A Carone.

94 records · Page 6Linked to original sources
PubMed1972

Serum albumin uptake in isolated perfused renal tubules. Quantitative and electron microscope radioautographic studies in three anatomical segments of the rabbit nephron.

Proximal convoluted, proximal straight, and cortical collecting tubular segments isolated from rabbit kidney were perfused with I 125-labeled rabbit serum albumin (RSA-I 125) in ultrafiltrate of serum for up to 3 hr After perfusion, the segments were fixed with glutaraldehyde, embedded in Epon, and either counted with a gamma spectrometer to quantitate protein accumulation or analyzed by electron microscope radioautography to sequentially localize radioactivity Proximal convoluted and proximal straight segments accumulate RSA-I 125 nearly linearly as a function of time whereas cortical collecting segments do not accumulate measurable amounts of protein. The rate of accumulation of RSA-I 125 in the proximal convoluted tubule is 2 6 times as great as that in the proximal straight tubule. Electron microscope radioautography of the isolated proximal tubule demonstrated that RSA-I 125 is taken up via small apical vesicles and tubular invaginations, released into large cytoplasmic vacuoles, and finally concentrated in membrane-bounded structures, some of which are acid phosphatase positive These results show that albumin is absorbed by proximal tubules and may be degraded intracellularly within lysosomes. In addition, less radioactivity was located at all times over the lateral intercellular and basilar labyrinthine spaces, suggesting that labeled albumin and/or its breakdown products may be transported across the peritubular cell membrane.

Acid Phosphatase↗
PubMedDate not supplied

Renal handling of proteins and peptides.

The kidney plays an important role in the metabolism of proteins and peptides. Current evidence indicates that only the proximal tubule possesses the mechanisms for absorption, transport and/or degradation of these substances. Large proteins and polypeptide molecules filtered by the glomerulus, are absorbed from proximal tubular fluid by luminal endocytosis into apical vacuoles which fuse with primary lysosomes where hydrolysis occurs followed by diffusion of metabolites out of the cells and into the blood. Recent evidence indicates that small peptides are handled by a different mechanism. It appears that small peptides are degraded at the luminal surface of the brush-border of proximal tubules, which contains many hydrolytic enzymes, by the process of membrane or contact digestion with reabsorption of the breakdown products. Proximal tubular mechanisms for handling of proteins and peptides are probably important biologically to conserve amino acids, inactive toxic substances and help regulate the circulating level of protein and peptide hormones.

Angiotensin II↗
PubMedDate not supplied

Platelets and the hemolytic-uremic syndrome.

Clinical studies suggest that the microthrombi characteristically found in hemolytic-uremic syndrome (HUS) may be the consequence of an uncontrolled platelet-endothelial interaction. A defect in prostacyclin production which is corrected by normal plasma may be the fundamental pathogenic mechanism. For this reason, efforts should be made to confirm the recent case reports which suggest that plasma infusion or exchange may be more effective than hemostatic inhibitors in the achievement of clinical remission in HUS.

Anticoagulants↗