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Biomedical subjects

T Cavallo

Publications and source records attributed to T Cavallo.

At least 109 records · Page 6Linked to original sources
PubMed1976

Nephrotoxic and cytoproliferative effects of streptozotocin: report of a patient with multiple hormone-secreting islet cell carcinoma.

The nephrotoxic and cytoproliferative side effects observed in a patient with Streptozotocin-treated, multiple hormone-secreting, pancreatic islet cell carcinoma are described. Streptozotocin induced prolonged partial remission of the patient's multiendocrine syndrome but resulted in progressive azotemia, which was controlled by temporary hemodialysis. A renal biopsy, the first to be reported in detail in such a condition, demonstrated a tubulo-interstitial nephritis and a glomerular alteration consisting of cellular nodules. At autopsy there were numerous bilateral renal cortical spindle cell "tumors" and cellular aggregates in glomeruli. These findings suggest that the tumorigenic effects of Streptozotocin demonstrated in animals may also occur in man.

Adenoma, Islet Cell↗
PubMed1976

Membranoproliferative glomerulonephritis. Localization of early components of complement in glomerular deposits.

A body of evidence suggests that in membranoproliferative glomerulonephritis (MPGN), complement is activated by the alternate pathway. Therefore, deposition of early components of complement should not be expected in glomeruli. The renal tissues of 16 patients--13 with classic MPGN and 3 with dense deposit disease, a variant of MPGN--were studied by light and electron microscopy and by means of elution and immunofluorescence for the localization of complement (C1q, C4, and C3), immunoglobulins (1gG, IgM, and 1gA), and other serum proteins. Variable amounts of C3, C4 and/or C1q, and IgM were detected in the glomeruli of all patients, whereas IgG and IgA were present, respectively, in 15 of 16 and 6 of 16 patients. Deposits were localized in mesangium and in peripheral capillary loops in a typical lobular distribution. The specificity of each antiserum was verified by immunodiffusion, immunoelectrophoresis, and blocking experiments utilizing unlabeled antibody. Glomerular-bound IgG was eluted with acid citrate buffer, suggesting that IgG might be complexed with antigen(s) in glomerular deposits. By light microscopy, lesions ranged from focal proliferation and lobulation to more severe involvement with typical splitting of glomerular basement membranes, sclerosis, and less frequently, crescent formation. Ultrastructurally, all patients with classic MPGN exhibited mesangial and subendothelial deposits, and in 5 of these patients, subepithelial deposits were demonstrated. With the exception of ultrastructural lesions, patients with the dense deposit variant lacked distinguishable features when compared with those with classic MPGN. The significance of these findings is discussed in relation to a) activation of complement and the possible role of an immune complex mechanism and b) the variability of the morphologic expression.

Adolescent↗
PubMed1976

An ultrastructural study of the glomerular slit diaphragm in New Zealand black/white mice.

Glomerular epithelial slit alterations and their relation to proteinuria have not been studied in detail in New Zealand Black/White (NZB/W) mice. The kidneys of proteinuric and nonproteinuric female NZB/W mice and normal Swiss albino mice were perfusion-fixed with tannic acid-glutaraldehyde and studied by light and electron microscopy. Semiquantitative studies were performed on full montages of glomeruli enlarged 10,000 times. Fine structural alterations of the epithelial slits, with emphasis on the slit diaphragm, were studied on semiserial thin sections. Proteinuric NZB/W mice with features of membraneous nephropathy exhibited: (1) wedging of electron-dense deposits below the slit diaphragm, (2) enlargement and distortion of interpedicel spaces, (3) displacement, folding, and stacking of slit diaphragms, (4) formation of occluding junctional complexes in residual slits, and (5) variable loss of foot processes. Similar alterations were not observed in controls or nonproteinuric NZB/W mice, including animals having complexes inglomerular mesangia but not in epithlialslits. These studies show that in NZB/W mice, abnormal protein excretion is associated with structural modification of the slit pore and suggest a role for such a component in the process of protein ex

Animals↗
PubMed1976

Cytochemical localization of endogenous peroxidase activity in renal medullary collecting tubules and papillary mucosa of the rat.

Endogenous peroxidase activity, as demonstrated by the technique of Graham and Karnovsky (Graham RC Jr, Karnovsky MJ: J Histochem Cytochem 14:291, 1966), was identified in medullary collecting tubule cells and in the cells of renal papillary mucosa of the rat. Peroxidase reactive sites were observed in the perinuclear cisterna, endoplasmic reticulum, and cytoplasmic vesicles of such cells. The specificity of the peroxidase reaction was verified by means of chemical inhibitors (NaN3, KCN, aminotriazole), denaturation of the enzyme by heat, exclusion or prior oxidation of substrate (diamino-benzidine), and high concentration of H2O2. Prolonged fixation (glutaraldehyde) improved cellular detail but diminished or abolished the peroxidase staining. When exogenous H2O2 was excluded from the incubating medium, a positive reaction was obtained suggesting that H2O2 can be endogenously generated. This observation was confirmed by degradation of tissue-formed H2O2 with beef liver catalase and by blocking endogenous generation of H2O2 with sodium pyruvate. These studies indicate that the reaction product is the result of an enzymatic reaction and that the enzyme is most likely a peroxidase. A similar staining reaction was not observed in other tubule segments, including cortical collecting tubules. The significance of this peroxidase activity is discussed in relation to the cellular localization and biosynthesis of renal medullary prostaglandins.

Animals↗
PubMed1974

The nephropathy of experimental hepatosplenic schistosomiasis.

The glomerular lesions induced in 10 chimpanzees infected with variable numbers of Schistosoma japonicum cercariae were studied by means of light and electron microscopy and fluorescent antibody technic. Ten animals served as controls; 5 were uninfected and 5 were only lightly infected. The animals were observed for periods ranging from 3 to 17 months, and by the time of sacrifice, all had developed advanced liver fibrosis. In general, the degree of glomerular injury was related to infection intensity and degree and duration of portal liver fibrosis. Some animals had terminal BUN elevation and slight proteinuria. By light and electron microscopy, in the initial stages, only part of the glomeruli were involved and exhibited mesangial matrix expansion and mesangial cell proliferation with intracellular hyaline droplets. At later stages, a larger number of glomeruli were affected and exhibited diffuse hypercellularity, glomerular basement thickening, mesangial sclerosis and less often, focal necrosis, crescent formation, synechiae and global hyalinization. In addition, there were discrete electron-dense deposits localized in the mesangial area in some glomeruli. Immunofluorescent studies utilizing antisera to chimpanzee gamma-globulin and complement (C3) and to human properdin disclosed only faint deposits of C3, apparently in mesangial areas. The association of hepatosplenic schistosomiasis and nephropathy, the possible role of schistosomal antigen and the mechanism(s) of such glomerular injuries are reviewed and compared with the disease in humans and other host species infected with Schistosoma.

Animals↗
PubMed1973

Ultrastructural autoradiographic studies of the early vasoproliferative response in tumor angiogenesis.

The early local vasoproliferative response induced by live tumor cells and an extract derived from such cells was studied in rat subcutaneous tissue by means of electron microscopy and ultrastructural autoradiography after local injections of tritium-labeled thymidine. DNA synthesis was localized in endothelial cells, pericytes, and perivascular cells 6 to 8 hours after exposure to 10(6) live Walker ascites tumor cells. At this time, DNA-synthesizing endothelial cells in parent vessels exhibited a continuous basement membrane and could not be readily differentiated, ultrastructurally, from control endothelium. At 48 to 50 hours, the number of labeled cells increased and there was ultrastructural evidence of regenerating endothelium: marked increase in ribosomes and endoplasmic reticulum, scarce or absent pinocytotic vesicles, attenuated or discontinuous basement membrane and marked irregularities in cytoplasmic surfaces. Labeled endothelial cells were present in parent vessels, as well as along newly formed sprouts. Autoradiographic and ultrastructural findings after tumor extract or live tumor cells at 48 hours were similar. Evidence was also presented that cells which were recognizable as pericytes, by ultrastructural criteria and by their localization within the basement membrane, were capable of DNA synthesis and mitosis.

Animals↗
PubMed1972

Tumor angiogenesis. Rapid induction of endothelial mitoses demonstrated by autoradiography.

Walker ascites tumor cells and an extract derived from such cells (tumor angiogenesis factor, TAF) were injected into the subcutaneous tissue of rats by using a dorsal air sac technique. At intervals thereafter, thymidine-(3)H was injected into the air sac and the tissues were examined by autoradiography and electron microscopy. Autoradiographs of 1micro thick Epon sections showed thymidine-(3)H labeling in endothelial cells of small vessels 1-3 mm from the site of implantation, as early as 6-8 hr after exposure to live tumor cells At this time interval endothelial cells appeared histologically normal. DNA synthesis by endothelium subsequently increased and within 48 hr new blood vessel formation was detected. The presence of thymidine-(3)H-labeled endothelial nuclei, endothelial mitoses, and regenerating-type endothelium was confirmed by electron microscopy. TAF also induced neovascularization and endothelial cell DNA synthesis after 48 hr. A similar response was not evoked in saline controls. Formic acid, which elicited a more intense inflammatory response, was associated with less endothelial labeling and neovascularization at the times studied. Pericytes and other connective tissue cells were also stimulated by live tumor cells and TAF. The mechanism of new blood vessel formation induced by tumors is still unknown but our findings argue against cytoplasmic contact or nonspecific inflammation as prerequisites for tumor angiogenesis.

Animals↗
PubMed1965

[Myelofibrosis].

Explore the source record for details and available documents.

Child↗
PubMedDate not supplied

Cardiac magnetic resonance imaging: technique and anatomy.

Recent advances achieved in Magnetic Resonance Imaging equipment and procedures allow a thorough study of the heart, yielding anatomic, functional and angiographic information. Spin-echo sequences are specific for heart morphology while gradient-echo sequences are fundamental to the functional study. Fast sequences reduce the examination times with the possibility of single breath-hold images. Coronary arteries can be directly visualized and cardiac perfusion can be assessed. Velocity encoded images allow flow quantification and with myocardial tagging, cardiac mechanics is accurately defined.

Blood Flow Velocity↗