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Biomedical subjects

K H Johnson

Publications and source records attributed to K H Johnson.

At least 109 records · Page 6Linked to original sources
PubMed1981

Feline insular amyloid. Ultrastructural evidence for intracellular formation by nonendocrine cells.

The objective of this ultrastructural study in cats was to investigate the early relationship of pancreatic islet cells with amyloid deposits. We used pancreatic islets from six domestic cats with minimal and apparently early amyloid deposits. Although amyloid deposits were occasionally arranged perpendicularly to beta cells, and rarely within deep invaginations of these cells, there was no consistent or convincing relationship of extracellular fibrils to any of the major islet stricted to, nongranulated perivascular cells in islets from two of the cats. Small and relatively electron-dense amyloid inclusions contained compact arrays of parallel fibrils. Larger inclusions were more electron-lucent and had loosely and randomly arranged fibrils. Indirect evidence strongly suggested that the fibril-laden inclusions resulted from intracellular production rather than from phagocytosis. The definitive identity of these amyloid-containing cells was not determined. However, these calls lacked secretory granules specific for known islet endocrine cell types and were topographically always located in close proximity to capillaries. The results of our study, therefore, do not directly support a morphologic association of amyloid fibril formation with typical islet endocrine cells. Our results do, however, draw attention to the possibility that nonendocrine cells play a key role in the pathogenesis of insular amyloidosis in the cat.

Amyloid↗
PubMed1981

Membranous nephropathy in a renal allograft. Its occurrence in a patient with previous anti-glomerular basement membrane disease.

Glomerulonephritis (GN) in transplant recipients has been attributed to recurrent as well as de novo disease. Although GN is thought to be common in renal allografts, few documented cases of de novo membranous GN in renal allografts have been reported. To our knowledge, this is the second reported case of membranous nephropathy of a renal allograft in a patient whose original disease was anti-glomerular basement membrane disease.

Basement Membrane↗
PubMed1981

Feline mammary hypertrophy/fibroadenoma complex: clinical and hormonal aspects.

Abnormal mammary enlargement, characterized microscopically by hyperplasia of both epithelial and mesenchymal tissues, was studied in 26 cats which were mostly young, sexually intact females. Clinicopathologic data indicated that mammary hypertrophy was likely progesterone-dependent. Administration of progestins preceded this condition in 5 cats, 4 of which were neutered. Serum progesterone concentrations (6.7 ng/ml) were increased in 1 of the 3 cats tested. Estrogen receptors were not found in the cytosols or nuclei of mammary tissues in the 2 cats studied. However, there were convincing 4S [3H]progesterone or 5S [3H]R5020 binding peaks which were suppressible by nonlabeled progestins. Progesterone receptors were measured at 14.9 and 8.6 fm/mg of protein, respectively. The apparent influence of progesterone, whether present as exogenous therapy in the male or female or as endogenous steroid of ovarian origin, has thus been demonstrated directly and indirectly in cats with mammary hypertrophy.

Adenofibroma↗
PubMed1979

Restrospective correlation of clinical and histologic findings of 189 exchanged kidneys.

Tissues samples from 189 unsuccessful renal allografts, 47 recovered at autopsy and the others removed surgically, were examined histologically by light microscopy. Tissues samples were obtained from cadaver kidneys that had been exchanged regionally for transplantation. Each allograft tissue sample was rated as to extent of pathologic changes denoting rejection and was classified accordingly. Surgical and autopsy reports, as well as clinical data, were then obtained and these were compared with the retrospective pathologic findings of this study. Our pathologic findings agreed with the original pathologic diagnosis as to presence or absence of rejection changes in 180 cases, but disagreed with the clinical diagnosis of rejection in 28 of the 63 cases with minimal or no histologic evidence of rejection. There was less disagreement with the clinical diagnosis for the 87 cases with histologic evidence of rejection which had been judged as sufficient to cause allograft loss, 70 having been clinically diagnosed as rejected. Disagreement occurred most often where the allograft had never functioned or had been lost within 3 months. Retrospective analysis did not disclose any association between rejection histology and preformed antibodies or length of kidney perfusion time. Sufficient allografts appeared to have been lost for reasons other than rejection to cast doubt on the validity of interpreting renal allograft data only by graft survival statistics.

Diagnosis, Differential↗
PubMed1976

Naturally occurring reticuloendotheliosis in turkeys: transmission.

This report describes the natural occurrence and experimental transmission of reticuloendotheliosis in a turkey flock. In the naturally affected turkeys, lesions were present in the liver, spleen, heart, intestines, and peripheral nerves, and were composed mainly of lymphoreticular cells. The disease was experimentally reproduced in turkey poults with cellfree tissue extracts of infected birds. A type-C RNA virus similar to reticuloendotheliosis virus (strain T) was present in the tissues of turkey poults experimentally inoculated. This virus was unrelated to the type-C RNA viruses of the avian leukosis sarcoma complex.

Animals↗
PubMed1975

Etiological factors, stages, and the role of the foreign body in foreign body tumorigenesis: a review.

Attempts were made to analyze the process of foreign body (FB) tumorigenesis and to identify etiologically significant factors by correlating information in the literature and recent experimental data from our labroatory. It appears that the process of FB tumorigenesis is dependent on sequence of specific conditions as expressed by the following criteria: (a) cellular proliferation and tissue infiltration during acute FB reaction; (b) fibrosis of the tissue capsule surrounding the FB; (c) quiescence of the tissue reaction, i. e., dormancy and phagocytic inactivity of FB-attached macrophages; and (d) availability of a FB surface for direct contact with clonal preneoplastic cells. There is no indication that the initial acquisition of neoplastic potential and the determination of specific tumor characteristics are based on direct physical or chemical reaction between cells and the FB. These etiological key events occur presumably in mesenchymal stem cells associated with the microvasculature no later than during the acute stage of FB reaction and certainly long before clonal descendants of these cells are first found in contact with the FB surface. In fact, there is no reason to assume that cells with neoplastic determination may be present in normal tissue prior to the introduction of a FB and that the FB would only create the conditions required for stepwise preneoplastic maturation.

Animals↗