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Biomedical subjects

J C Lewis

Publications and source records attributed to J C Lewis.

At least 145 records · Page 8Linked to original sources
PubMed1979

Ultrastructural characteristics of dog and human platelets adherent to native and collagen-coupled cuprophan.

Adhesion of human and dog platelets to native and collagen-coupled Cuprophan under defined flow conditions was studied by scanning and transmission electron microscopy. Dog platelets, singly adherent to and uniformly distributed on both native and collagen-coupled Cuprophan, extend slender pseudopods across the surface without evidence of degranulation. Human platelets, while not adhering to native Cuprophan, formed irregularly shaped, semi-confluent cytoplasmic sheets on the collagen-coupled surface. Extensive cytoplasmic reorganization and degranulation suggests a post-release state of the human platelets. Aspirin had no apparent effect on either human or dog platelet adhesion or upon the apparent release state of the human platelets.

Adsorption↗
PubMed1979

A study to evaluate non-fatal rabies in animals.

Brains and salivary glands of stray dogs, cats and wild mammals were examined for latent rabies virus. Sera of these animals were tested for rabits neutralizing antibody. Dogs and rodents of the gerbil species were experimentally infected with rabies viruses tryping to produce nonfatal rabies. The following conclusions are made: 1. Naturally occurring nonfatal rabies infection evidenced by recovery of the virus was not present in the stray dogs examined and could not be produced experimentally. 2. Among wild gerbils showing no signs of disease, recovery of (latent) virus was possible but this condition could not be reproduced experimentally. However they could have been in the incubation stage. 3. Development of rabies neutralizing antibody did not occur naturally in wild rodents, but occurred in dogs. Antibody to rabies was detected in surviving gerbils after experimental infection. The antibody probably develops subsequent to sublinical nonfatal infection. 4. Non-fatal infection, indicated either by recovery of rabies virus or detection of neutralizing antibody, was not detected among the examined cats.

Animals↗
PubMed1978

Localization of the guinea pig eosinophil major basic protein to the core of the granule.

The localization of the guinea pig eosinophil major basic protein (MBP) within the cell was investigated by the use of immunoelectron microscopy and by isolation of the granule crystalloids. First, by immunoperoxidase electron microscopy, we found that the MBP of eosinophil granules is contained within the crystalloid core of the granule. Specific staining of cores was present when rabbit antiserum to MBP was used as the first stage antibody in a double antibody staining procedure, whereas staining was not seen when normal rabbit serum was used as the first stage antibody. Second, crystalloids were isolated from eosinophil granules by disruption in 0.1% Triton X-100 and centrifugation through a cushion of 50% sucrose. Highly purified core preparations yielded essentially a single band when analyzed by electrophoresis on polyacrylamide gels containing 1% sodium dodecyl sulfate (SDS). The E1%1cm of the core protein was 26.8 +/- 1.0 (X +/- SEM); the E1%1cm for the MBP was 26.3. The core protein could not be distinguished from the MBP by radioimmunoassay (RIA) and essentially all of the protein in the core preparations could be accounted for as MBP. The results indicate that the MBP is contained in the core of the guinea pig eosinophil granule and that it is probably the only protein present in the core.

Animals↗
PubMed1978

Platelet 5-hydroxytryptamine storage in the carcinoid syndrome.

The uptake and storage of 5-hydroxytryptamine by human platelets from normal donors and patients with the carcinoid syndrome are reported. When platelets were incubated in the presence of 3H-5-hydroxytryptamine (50 microM), an initial phase of rapid uptake was observed until 5-hydroxytryptamine levels of 1--2 microgram/10(9) cells were reached. Further accumulation occurred more slowly. Electron microscopic autoradiography of cells after 5-hydroxytryptamine uptake for 60 minutes revealed that in platelets from normal donors most of the label was localized in membranes (52%), alpha granules (27%), and cytoplasm (4%). Dense bodies were associated with 18% of the silver grains. Similar membrane (50%) and alpha-granule (27%) labeling was found with platelets from patients with carcinoid syndrome. However, more cytoplasmic labeling (10%) and less dense-body labeling (11%) were found with these cells. The results support a hypothesis of two or more sites for storage of 5-hydroxytryptamine in mammalian platelets and suggest that minimal exchange between cytoplasmic and dense-body amines occurs in carcinoid platelets.

Autoradiography↗
PubMed1978

Resistance to arteriosclerosis in pigs with von Willebrand's disease. Spontaneous and high cholesterol diet-induced arteriosclerosis.

The aortas of 11 pigs (aged 1-3 yr) with homozygous von Willebrand's disease (vWd) were compared with those of 11 normal pigs of the same ages. Six of the controls exhibited multiple arteriosclerotic plaques with intimal thickening of 63-130 mum. In contrast, none of the pigs with vWd had multiple plaques, and only one had a lesion >2 mm in diameter. In a subsequent study, 3-mo-old pigs (11 controls and 7 with homozygous vWd) were placed on a 2% cholesterol diet for up to 6 mo. All of the controls developed arteriosclerotic plaques in the aorta, and in nine of the controls, at least 13% of the entire surface was involved. Intimal thickness ranged up to 390 mum. In contrast, four of the pigs with vWd did not develop such lesions, two developed arteriosclerotic lesions affecting 6 and 7% of the aortic surface, and the seventh had 13% of the aortic surface involved. Most of the pigs with vWd, however, developed flat fatty lesions in contrast to the normal pigs whether on the normal or the high cholesterol diet. There was blue staining of the flat fatty lesions when two pigs with vWd were injected with Evans blue dye antemortem. By electron microscopy, severe endothelial damage was apparent, but there was no intimal proliferation. The coincidence of the impaired platelet-arterial wall interaction and lack of arteriosclerosis in this bleeding disease is discussed.

Animals↗
PubMed1978

Ultrastructural studies of platelets of von Willebrand and normal swine.

Platelets from normal pigs and pigs with von Willebrand's disease were studied by ultrastructural and scanning electron microscopy. The majority of resting platelets were discoid or abortive-dendritic in gross morphology with an average size of 2.6 micrometer. The number of alpha-granules per platelet section was varied; however, a highly significant positive association was found between platelet size and the number of alpha-granules. These studies characterize porcine platelets more definitively and clearly establish the similarities between platelets from normal and those from von Willebrand pigs.

Animals↗
PubMed1977

Specific protein synthesis in isolated epithelium of guinea-pig seminal vesicle. Effects of castration and androgen replacement.

Four intrinsic soluble secretory proteins are synthesized in vitro by isolated seminal-vesicle mucosa from sexually mature guinea pigs. Newly synthesized specific proteins labelled with [(14)C]glycine and [(14)C]lysine were precipitated by using double-antibody immunoprecipitation techniques and their radioactivity was assessed. Rates of synthesis were determined on each of 5 days after castration. By 5 days after castration the wet weight of the epithelium decreased to 42% of intact control values; the absolute amount of specific protein synthesized in vitro after 60min incubation decreased to 28% and the 27500g cytoplasmic protein content decreased to 31%. Thus androgen deprivation leads to a decrease in general protein synthesis in vivo, as well as to a decrease in specific protein synthesis in vitro. Specific protein synthesis comprised 76% of the total protein formed in isolated tissue from animals 5 days after castration as compared with 99-100% in tissue from intact animals. At 72h after an injection of testosterone or dihydrotestosterone, seminal-vesicle epithelium wet weight, cytoplasmic protein content and capability for synthesizing specific proteins in vitro were restored to approx. 70% of normal values. At 72h after onset of therapy with 3alpha-androstanediol, both epithelium wet weight and cytoplasmic protein content had increased significantly, but without a corresponding increase in the capability of the isolated tissue to synthesize specific proteins. The soluble labelled proteins synthesized in vitro by isolated epithelium from intact animals during 60 or 120min incubation were essentially entirely immunoprecipitable, i.e. specific. In contrast, approx. 29% of all soluble protein newly synthesized by isolated epithelium from animals 5 days after castration was acid-precipitable, but not immunoprecipitable, i.e. ;non-specific'. The injection of testosterone into castrated animals inhibited the synthesis of the non-specific fraction by isolated tissue. The effects of castration on the ultrastructure of guinea-pig seminal-vesicle epithelium are also presented.

Androgens↗
PubMed1977

Endothelial damage and thrombocyte adhesion in pigeon atherosclerosis.

Scanning electron microscopy studies of spontaneously occurring atherosclerosis in pigeons reveal dramatic alterations in endothelial integrity. An irregular endothelium at the intimal cushion region of 5-week-old birds gives rise to extensive areas of pitted endothelium and subendothelial exposure. Thrombocytes, thrombocyte aggregates, and leukocytes are associated with the developing lesion.

Animals↗
PubMed1977

Ultrastructural studies of the superior cervical trunk of the mouse: distribution, cytochemistry and stability of fibrous elements in preganglionic fibers.

The ultrastructure of axons in the preganglionic cervical sympathetic trunk of the mouse is described with emphasis on the number, distribution and stability of fibrous elements in the axoplasm. Neurofilaments outnumbered microtubules in myelinated and non-myelinated axons of all sizes, and the ratio of neurofilaments to microtubules in non-myelinated axons at each point studied was fairly consistent and independent of axonal diameter. The density of neurofilaments and microtubules, however, was greater in axons of progressively smaller diameter. In non-myelinated axons and small myelinated axons neurofilaments were uniformly distributed throughout the axoplasm resulting in minimum and maximum interfilament distances of 300 angstrom and 500 angstrom respectively; the spacing of fibrous elements within any one axon was dependent upon its diameter and position with respect to the superior cervical ganglion in the preganglionic trunk. The maximum interfilament distance was also found in large myelinated axons where neurofilaments, occurring in fascicles, were separated by distances of approximately 500 angstroms. Cytochemical staining of axons with lanthanum hydroxide, ruthenium red or alkaline bismuth delineated the delicate filamentous matrix interconnecting microtubules, neurofilaments and other organelles in the axoplasm. Alkaline bismuth stain was most intense in myelinated axons where heaviest deposition of reaction product was associated with neurofilaments. Treatment in vitro of the cervical sympathetic trunk with 5 X 10(-5) M vinblastine sulfate dissociated microtubules and induced formation of crystalline arrays of "tubular" elements. A uniform center to center spacing of 250-300 angstrom was found for crystalloids in non-myelinted axons; however, in myelinated axons the center to center spacing was not uniform and varied in the range 300-600 angstrom. Neurofilaments and their surface projections were unaffected by vinblastine. Fixation in the presence of lanthanum enhanced delineation of crystalloid elements. Exposure of 0-4 degrees C for up to three hours had no consistent effect on microtubules or neurofilaments. In contrast, cold treatment disrupted the delicate axonal matrix and resulted in the formation of aggregates of coarse flocculent material in the axoplasm.

Animals↗