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Biomedical subjects

C Weber

Publications and source records attributed to C Weber.

At least 379 records · Page 21Linked to original sources
PubMed1976

U-shaped backward contour masking during stroboscopic motion.

Two stationary and spatially separated visual stimuli, presented briefly and successively in time, are known to produce stroboscopic motion whose vividness is a U-shaped function of the stimulus onset asynchrony. Contour masking is also known to occur under such stimulus conditions. The findings show that the contour masking is confined to only the first stimulus and that it, like metacontrast, is a backward U-shaped function of the stimulus onset asynchrony. A simple model, based on known psychophysical and neurophysiological properties, is proposed to explain these results.

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PubMed1976

Pancreatic islet isografts, allografts, and xenografts: comparison of morphology and function.

Neonatal rat pancreatic islets were transplanted intraperitoneally into adult streptozotocin-diabetic rats and mice. Isologous pancreatic islet recipients (12 of 12) showed consistent and permanent reconstitution of normoglycemia and normal weight gain as well as readjustment to normal of intake of water, urine volume, and glucose excretion for greater than 10 months when compared to age-matched normal (ten) and diabetic (20) controls. Revascularized isologous islet grafts were found to be adherent to both visceral and parietal peritoneum. Pancreatic islet allografts (ten) and allografts and xenografts did not appear to differ markedly; both were characterized by dense round-cell infiltration within 5 days after transplantation.

Animals↗
PubMed1976

The kidney in streptozotocin diabetic rats. Morphologic, ultrastructural, and function studies.

In order to study the nephropathy associated with experimental streptozotocin diabetes, serila morphologic, ultrastructural, immunohistologic, and functional studies were done in diabetic Lewis rats to study the course of the nephropathy. Early in the course of diabetes, these animals developed an increase in mesangial matrix, with electron-dense material, IgG, and C3 in the mesangium. These alterations were progressive. Mesangial bars, proximal tubular vacuolization, and myeloid bodies were also present. Progressive increase in protein excretion and increase in creatinine clearance were observed. Hyperglycemia was accompanied by weight loss, persistent glycosuris, hyperphosphaturia, and hypercalcuria. Urinary glomerular basement membrane-like protein and major urinary protein were decreased. Normal age-matched controls showed no abnormalities. Some of the changes observed in diabetic rats are present in human diabetes.

Animals↗
PubMed1975

Cardiac heterotransplantation. Morphological and immunohistological studies.

A vascularized heterograft model using outbred strains of animals was developed by transplanting mouse hearts heterotopically into rats. With this species desparity rapid but not immediate graft rejection was observed, with a predictably narrow range of graft survival times. Morphological and immunohistological studies showed early deposition of fibrinogen and vascular and myocardial inflammation without prominent or consistent localization of either IgG or C3. Later more extensive changes were observed, and deposition of IgG and C3 were more prominent in the grafts. Pretreatment of the recipient with cyclophosphamide alone or cyclophosphamide plus antigen prolonged graft survival; however, no statistically significant difference was noted between these groups. Morphological and immunohistological alterations preceded clinical rejection, and tissue injury appeared to be mediated by humoral and cellular immune mechanisms and by the coagulation system. This model is potentially useful for the study of heterotransplantation.

Animals↗
PubMed1975

Pancreatic transplantation in diabetic rats: renal function, morphology, ultrastructure, and immunohistology.

Serial renal morphologic, ultrastructural immunohisotlogic and functional studies were done on diabetic Lewis rats to evaluate the course of nephropathy and to study the effects of early pancreatic isografts on renal disease associated with streptozotocin diabetes. Three groups of experimental animals and one group of agematched controls were used. Group 1 consisted of 12 animals which were made diabetic with streptozotocin and which did not receive transplants. Early in the course of diabetes, these animals developed an increase in mesangial matrix, electron-dense material in themesangium, with immunoglobulin G, C3, and occasionally fibrinogen deposits in the glomerular mesangium. Alterations were progressive and mesangial bars, proximal tubular degeneration, tubular vacuolization, and myeloid figureswere present later. Progressive increase in protein excretion and increase in glomerular filtration rate were observed. Persistent glycosuria, hyperphosphaturia, andhypercalcuria. In contrast, only an occasional animal from Groups 2 and 3 with a pancreatic transplant showed renal in age-matched controls. These studies have demonstrated the evolution of renal glomerular and tubular changes in streptozotocin diabetic rats, and they have showed functional, and immunohistochemical changes.

Animals↗
PubMed1975

Xenotransplantation of piscine islets into hyperglycemic rats.

Xenotransplantation of piscine islets into hyperglycemic rats usually lowers the blood sugar level of the recipient. The duration of this effect is prolonged by irradiation of the host or by enclosing donor tissue in synthetic envelopes. This prolongation appears to be related to interference with the host's ability to reject the graft; the duration of the prolongation may be limited by the host tissue reaction surrounding the envelope. The availability of anatomically separate piscine islet tissue makes it potentially useful for xenotransplantation into mammals.

Animals↗