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Biomedical subjects

R L Reddick

Publications and source records attributed to R L Reddick.

At least 73 records · Page 4Linked to original sources
PubMed1984

Choroidal microvascular repair after argon laser photocoagulation. Ultrastructural observations.

Acute laser injury to the tapetum of the feline retina produces thrombosis of the choriocapillaris. Early changes are characterized by the appearance of platelet-fibrin thrombi within capillary loops and disruption of endothelial integrity. By 4 days, thrombi have disappeared, and the endothelium shows regenerative changes. No endothelial cell mitotic activity is seen. The endothelial cytoplasm becomes plump, and there is a loss of the fenestrations adjacent to Bruch's membrane. By 10-20 days, the capillary structure shows gradual restoration. At 30 days, endothelial cell fenestrae are clearly evident adjacent to Bruch's membrane. The reparative process in this model appears to evolve as a result of thrombolysis and endothelial cell activation.

Animals↗
PubMed1983

Immunologic and ultrastructural characterization of the small cell population in malignant thymoma.

A case of malignant thymoma is presented. The electron microscopic (EM) findings of the lymphocyte-epithelial relationships were similar to these previously described. Utilizing specific monoclonal antibodies to differentiate thymocytes from T-lymphocytes, the small cell population with ultrastructural features of lymphoid cells consisted of true thymocytes rather than peripheral T-lymphocytes. The latter finding may prove to be of importance in differentiating thymomas from reactive or most neoplastic lymphocytic processes involving the thymus gland.

Female↗
PubMed1983

Characterization of a pure heterologous sarcoma of the uterus: rhabdomyosarcoma of the corpus.

A case of a pure heterologous sarcoma of the uterine corpus composed exclusively of rhabdomyosarcomatous elements has been studied by multiple morphologic and biochemical techniques. The neoplasm filled the endometrial cavity and protruded out the cervical os, but the myometrium was only superficially invaded. The tumor did not extend outside the corpus. The pathologic features are discussed in detail. Evidence of striated muscle differentiation could be identified on light microscopic and ultrastructural examination. Immunoperoxidase staining of tumor cells with antibodies to myoglobin were positive. Histochemical preparations for lactate dehydrogenase, succinic dehydrogenase, and acid phosphatase were also positive in neoplastic cells. Other stains gave equivocal or negative results. These findings are discussed in comparison with previous reports.

Acid Phosphatase↗
PubMed1982

Sertoli-Leydig cell tumor of the ovary with teratomatous differentiation: clinicopathologic considerations.

A patient with recurrent Sertoli-Leydig cell tumor is described. The light and ultrastructural findings are illustrated. The tumor recurred first as a poorly differentiated tumor with rhabdomyoblastic differentiation. Following chemotherapy the next recurrence exhibited well differentiated Sertoli-Leydig cell elements. These findings may reflect the capability of this tumor type to undergo chemotherapeutic transformation similar to the transformation which has been described in germ cell tumors of the ovary and testis. This observation may be of importance in the clinical management of patients with poorly differentiated Sertoli-Leydig cell tumors.

Adult↗
PubMed1982

Effect of carbon monoxide on atherogenesis in normal pigs and pigs with von Willebrand's disease.

The extent of coronary and aortic atherosclerosis was examined in pigs following balloon-catheter injury of coronary arteries and subsequent feeding of an atherogenic diet for 4 months. The pigs were either exposed intermittently to 100 ppm carbon monoxide or to ambient air alone. Three types of pigs were used: normals, homozygotes for von Willebrand's disease (bleeders), and heterozygotes (carriers). The 3 types of pigs developed coronary artery intimal lesions of similar thickness. Aortic lesions, quantified as percent of aortic surface involved with sudanophilia and raised fibrous plaques, were slightly less extensive in bleeder pigs than in normals. Carbon monoxide exposure did not increase the thickness of coronary artery intimal lesions, nor did it increase the percent of aortic surface involved with sudanophilia or raised fibrous lesions. These results suggest that exposure to low levels of carbon monoxide does not perceptibly enhance atherogenesis induced by hypercholesterolemia. None of 14 bleeder pigs showed evidence of myocardial infarction, despite significant coronary artery narrowing. Of the 24 normal and carrier pigs, 5 showed myocardial infarction. Four of these 5 pigs were exposed to carbon monoxide, while 1 was not exposed. These findings suggest that exposure to low levels of carbon monoxide may increase the incidence of myocardial infarction and that the absence of von Willebrand factor may be protective.

Animals↗
PubMed1982

Platelet adhesion to damaged coronary arteries: Comparison in normal and von Willebrand disease swine.

The early response to coronary artery injury was investigated in normal swine and in swine with von Willebrand disease (vWD). Thirty minutes after coronary endothelial denudation, a monolayer of platelets was adherent to areas of simple injury in both bleeder and normal swine. The number of adherent platelets was not significantly different in the two phenotypes. Injury involving the media of the vessel produced platelet-fibrin thrombi. Platelet activation, as judged by pseudopod formation and platelet spreading over areas of simple injury, was significantly less in bleeder animals than in normal animals. These studies suggest that chemotaxis and initial contact adhesion of platelets to injured arterial wall is independent of the von Willebrand factor. On the other hand, the spreading and activation of platelets on the subendothelium appear to be dependent on the presence of plasma von Willebrand factor. Through this mechanism von Willebrand factor may contribute to arterial thrombosis and atherogenesis.

Animals↗
PubMed1982

Diffuse T-cell lymphoma preceded by nodular lymphoma.

A patient with a nodular lymphoma morphologically indistinguishable from follicular B-cell lymphoma subsequently developed a diffuse T-cell lymphoma. This T-cell lymphoma displayed characteristics analogous to mature T-lymphocytes, and typed as a suppressor/cytotoxic T-cell with the monoclonal antibodies. The light and electron microscopy morphology of the T-cell lymphoma was similar to that reported for node-based T-cell lymphomas. There was a polymorphous proliferation of variably transformed lymphocytes including immunoblasts. This case could represent either a nodular form of T-cell lymphoma converting to a diffuse T-cell lymphoma, or a follicular B-cell lymphoma preceding, and possibly inducing, a suppressor T-cell lymphoma.

Adult↗
PubMed1981

Hemangiopericytoma: a light microscopic and ultrastructural study.

An ultrastructural study of three cases of hemangiopericytoma showed cells partially or completely enveloped by well-formed basement membrane and basement membrane-like material. The cells exhibited prominent cytoplasmic filaments, some showing dense body formation, interdigitating cytoplasmic processes, and pinocytotic vesicles. A review of the literature revealed only 19 other cases of hemangiopericytoma studied by electron microscopy, and these included seven cases of meningeal origin ("angioblastic meningioma"). The most consistent feature seen in all but two cases was the presence of a basal lamina or basal lamina-like material either partially or completely surrounding tumor cells and separating endothelial cells from pericytes. The light microscopic diagnosis of hemangiopericytoma is difficult, and there is a tendency to append the diagnosis to a variety of other tumors with a prominent vascular pattern in which other specific diagnoses are not immediately evident. The presence, ultrastructurally, of well-developed basement membrane, myogenic type filaments, and pinocytotic vesicles in a tumor with light microscopic features suggestive of hemangiopericytoma would consolidate the diagnosis and usually eliminate diagnostic uncertainty.

Aged↗
PubMed1981

Susceptibility to atherosclerosis in aortas and coronary arteries of swine with von Willebrand's disease.

The development of coronary and aortic atherosclerosis was determined after balloon catheter injury of coronary arteries and administration of an atherogenic diet in normal pigs and pigs that were homozygous and heterozygous for von Willebrand's disease. Coronary atherosclerosis developed to a similar degree in all three phenotypic groups. The mean intimal thickness at the site of maximal thickness in ballooned vessels was .51 mm in the normal pigs, .67 mm in carrier pigs, and .55 mm in bleeder pigs. The intimal thickness of non-ballooned vessels was .28 mm in normal pigs, .28 mm in carrier pigs, and .35 mm in bleeder pigs. Fibrous lesions of atherosclerosis covered an average of 3.88% of the aorta in normal pigs, 2.83% in carrier pigs, and 2.37% in bleeder pigs. The difference between the aortic lesions of normal animals and bleeders was significant (P less than .05). Absence of von Willebrand factor was associated with limited resistance to atherosclerosis in the aortas of experimental pigs but did not affect the development of atherosclerosis in either ballooned or nonballooned coronary arteries. These findings suggest, first, that von Willebrand factor function is not essential to the development of the atherosclerotic lesion in this model and, second, that the role of the von Willebrand factor in the development of atherosclerosis is complicated and appears to involve interaction with variables not yet defined.

Animals↗
PubMed1980

Osteogenic sarcoma: a study of the ultrastructure.

Ultrastructural examination of 26 osteogenic sarcomas has revealed that in addition to the basic osteoblast comprising the tumor, five additional cell types may be identified. These include chondroblasts, osteocytes, undifferentiated cells and myofibroblasts. The latter cell type has not been reported in previous studies of medullary osteosarcomas. The relative portions of the cell types varied as to the type of osteogenic sarcoma studied. Osteoid production, the single diagnostic feature of these tumors, was evident and the various ultrastructural appearances of this material are shown. One case of an osteogenic sarcoma that arose in Paget's disease of bone is described and did not differ ultrastructurally from the conventional medullary osteogenic sarcoma. Our studies have shown that osteogenic sarcoma may share common ultrastructural features with other sarcomas involving bone and soft tissue and that the basic difference between osteogenic sarcoma and soft-tissue sarcomas is the presence of osteoid in the former and differing cytoplasmic differentiation in the latter category of tumors.

Bone Neoplasms↗
PubMed1980

Parosteal osteogenic sarcoma. Ultrastructural observations in three cases.

Ultrastructural study of three parosteal osteogenic sarcomas showed this type of tumor to contain numerous myofibroblasts. These cells were admixed with occasional cells resembling osteoblasts and fibroblasts. Cartilaginous areas showed the typical arrangement of cartilage cells embedded in a dense collagen matrix. Ultrastructural examination of a recurrent lesion revealed the presence of numerous undifferentiated cells as well as the types of cells just described. In addition, desmosomes were evident between the more undifferentiated cells. The ultrastructural study of these tumors shows that parosteal osteogenic sarcomas are ultrastructurally a distinctive type of osteogenic sarcoma.

Adolescent↗
PubMed1980

Ultrastructural organization of the Reed-Sternberg cell: its resemblance to cells of the monocyte-macrophage system.

A dichotomy exists in the characterizations of the histogenesis of Hodgkin's disease. The Reed-Sternberg cell has been shown to possess functional properties both of lymphocytes and of mononuclear phagocytes. The majority of ultrastructural studies support the lymphocytic origin although a conflicting report describes some features of "histiocytic" cells [9]. In our study of four cases of Hodgkin's disease, the Reed-Sternberg cells contained a well-developed Golgi, moderate numbers of free polyribosomes and smooth and rough endoplasmic reticulum, variable numbers of lysosomes, lipid droplets, glycogen, fibrillar bodies, and irregular cytoplasmic processes. The number, size, and organization of cytoplasmic organelles are more consistent with a mononuclear phagocyte than a transformed lymphocyte and are similar to those seen in monoblastic leukemias. These findings support the concept of the derivation of the Reed-Sternberg cell from a monocyte-macrophage.

Adult↗
PubMed1979

Primary osteogenic sarcoma of the heart.

The clinical course of a 17-year-old boy with primary osteogenic sarcoma of the left atrium with partial obstruction of the mitral valve and the right pulmonary veins is described. After operative removal of the tumor, echocardiography documented its rapid recurrence. Despite two subsequent open-heart operations and adjuvant chemotherapy and radiotherapy, the patient died twenty-one months after the initial symptoms. Previous reports of such tumors are reviewed, and technical difficulties of removal are discussed.

Adolescent↗
PubMed1979

Malignant soft tissue tumors (malignant fibrous histiocytoma, pleomorphic liposarcoma, and pleomorphic rhabdomyosarcoma): an electron microscopic study.

A comparative ultrastructural analysis of malignant soft tissue tumors (malignant fibrous histiocytoma, pleomorphic liposarcoma, and pleomorphic rhabdomyosarcoma) revealed similar ultrastructural features in this group of tumors. However, by electron microscopy these tumors can be differentiated on the basis of cytoplasmic and extracytoplasmic features (myosin filaments, lipid droplets, and perinuclear intermediate filaments, for example). This is even true of less well differentiated tumors and tumor cells. These findings support and amplify the concept of a common histogenesis for tumors of mesenchymal origin. Paradoxical features observed by light microscopy warrant further study by electron microscopy if the correct diagnosis is to be made in atypical cases, such as apparent malignant fibrous histiocytoma with cross striations.

Adult↗
PubMed1979

The microscopic characterization of multinucleated giant cells formed on polymeric surfaces perfused with blood.

Multinucleated, foreign body giant cells were formed by the fusion of blood monocytes on polymeric membranes perfused with blood during extended extracorporeal circulation. In the current study, heparinized blood, flowing in an arteriovenous shunt in a sheep, perfused polycarbonate, polypropylene and silicone rubber membranes of a recently developed bioartificial tissue culture system. The multinucleated giant cells were studied by light, scanning electron, and transmission electron microscopy, after membrane perfusion for periods of one to two weeks. The giant cells, which were the predominant cellular components of the blood-polymer interface layer, contained from a few to more that one hundred nuclei and varied in diameter up to 400 microns. The cellular interaction with the three membrane types was similar, although fewer mononuclear cells were observed adhering to the silicone rubber membrane. The presence or absence of micropores in the membranes had no effect on the formation of giant cells, nor did the presence of foreign tissue in culture behind the microporous membranes. High blood flow rates and chronic anticoagulation with heparin permitted observation of this foreign body reaction of blood independent of thrombosis.

Animals↗