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Biomedical subjects

J C Lewis

Publications and source records attributed to J C Lewis.

At least 163 records · Page 9Linked to original sources
PubMed1977

Rabbit ileal mucosa exposed to fatty acids, bile acids, and other secretagogues. Scanning electron microscopic appearances.

Segments of rabbit ileum were examined by scanning electron microscopy (SEM) after exposure to various compounds known to stimulate fluid secretion in the small intestine. After perfusion with ricinoleate (castor oil) at a 10 mM concentration, striking changes were observed at villus tips and on the apicolateral surfaces of villi; erosions at tips were confirmed by light microscopy of the same pieces of tissue examined by SEM. The appearances after ricinoleate were reversed in part during perfusion with control buffer for 2 hr. Statistical comparisons between control perfused, treated, and reversal tissues showed that the "damage" produced by ricinoleate, and its reversal, was significant statistically. Tissues treated with other intestinal secretagogues, oleic acid (10 mM), deoxycholic acid (4 mM), cholic acid (4 mM), dioctyl sodium sulfosuccinate (6 mM), and cholera toxin (1 microgram/ml) also showed surface changes by SEM. Fluid secretion, produced by an osmotic agent (mannitol) was not associated with "damage." Changes in structure of the mucosal surface after exposure to intestinal secretagogues should be considered as one possible mechanism of impaired fluid transport.

Animals↗
PubMed1977

Cultured aortic endothelial cells from pigs with von Willebrand disease: in vitro model for studying the molecular defect(s) of the disease.

Aortic endothelial cells from normal pigs and pigs with von Willebrand disease have been established in long-term cultures. Both cultures appeared similar in terms of general growth characteristics, morphologic features and ultrastructure. Immunofluorescent staining of these cultures with chicken (or rabbit) antiporcine ristocetin-Willebrand factor sera (or IgG) resulted in extensive perinuclear staining of the cells in both cultures. Additionally, staining of semiconfluent cultures of normal cells for ristocetin-Willebrand factor revealed an extensive meshwork of distinct, immunologically identifiable ristocetin-Willebrand factor-containing filaments between cells. Immunoreactive material was considerably decreased and more diffuse between cells in semiconfluent cultures from affected pigs. Through immunocytochemical staining with peroxidase-coupled antiserum, the filaments (of indeterminate length) were found to have a diameter of approximately 300 A. Finally, washed porcine platelets interacted extensively with scrape-damaged cultures of affected endothelial cells. This interaction of platelets with damaged normal cultures was abolished by pretreatment of the cultures with rabbit antiporcine ristocetin-Willebrand factor IgG.

Animals↗
PubMed1977

Platelet adhesion to foreign surfaces under controlled conditions of whole blood flow: human vs rabbit, dog, calf, sheep, pig, macaque, and baboon.

Our results reveal significant differences between mammalian species with respect to platelet adhesion to foreign surfaces exposed to heparinized, flowing blood. In particular, we have demonstrated the following: 1) At a surface shear rate characteristic of shear rates in mammalian arteries, human platelet adhesion (and that of calf, baboon, macaque, hog or sheep) is negligible in comparison to dog or rabbit platelet adhesion after 10 mins of blood flow. 2) The species differences are biomaterial dependent: the human-dog difference is present with Cuprophan or Avcothane, but absent with compressed Gore-Tex or fluorinated ethylcellulose. (The platelets of humans and dogs adhere to comparable degrees on the latter 2 biomaterials.) 3) With Cuprophan and recirculated blood, the human-dog difference persists at 30 and 180 mins. 4) By means of videomicroscopy, the species differences are unlikely only to be an artifact of the possible formation and embolization of surface-adherent aggregates. Tests for the thromboresistance of candidate biomaterials and for platelet adhesion under controlled flow conditions must therefore begin to take into account differences between humans and other species.

Animals↗
PubMed1977

Erythrocyte morphology in genetic defects of the Rh and Kell blood group systems.

Absence of KX antigen and of normal expression of the Kell system antigens is associated with bizarre red blood cell morphology when observed by either light or scanning electron microscopy. Numerous acanthocytes and dacryocytes have been observed in the peripheral blood smear of an apparently healthy individual with McLeod-phenotype blood, in a male patient with type II chronic granulomatous disease who had a shortened 51Cr red blood cell survival time, and in a minor population of the red blood cells of his carrier mother.

Blood Group Antigens↗
PubMed1977

Perfusion of rabbit colon with ricinoleic acid: dose-related mucosal injury, fluid secretion, and increased permeability.

Morphology of the rabbit colon was examined by light and scanning electron microscopy after perfusion of the organ with 2.5, 5.0, 7.5, and 10 mM sodium ricinoleate. Colons perfused with control buffer showed the expected normal appearances, whereas ricinoleate produced desquamation of surface epithelial cells. Surface changes in the colon were comparable with those reported after similar treatment of the rabbit ileum. Concomitant with these histological changes was loss of DNA into the lumen of the colon. Dose-related changes in net fluid transport and mucosal permeability (as assessed by lumen to plasma flux of low molecular weight polyethylene glycols and plasma to lumen flux of urea and creatinine) were also associated with ricinoleate perfusion. These structural and functional alterations may contribute to intraluminal accumulation of fluid and catharsis that can result from administration of ricinoleic acid (castor oil). The findings might also pertain to the pathophysiology of steatorrheal diseases, because dietary fatty acids of similar chemical structure are known to have comparable effects on the intestinal mucosa.

Animals↗
PubMed1977

Spontaneous endothelial cell injury in the intimal cushions of atherosclerotic pigeons.

Since endothelial damage precedes sterol accumulation, platelet factor 4-like activity elevations and alterations in thrombocyte adhesiveness, it clearly is one of the earliest events in the pathogenesis of spontaneous pigeon atherosclerosis. Although the relationships among endothelial damage and the other events have not been elucidated, it is conceivable that products released from thrombocytes subsequent to adhesion on damaged endothelium may trigger other localized changes in the intimal cushion area and lead to the progression of atherosclerosis.

Animals↗
PubMed1976

Ultrastructural cytochemistry of platelets and megakaryocytes in the carcinoid syndrome.

Platelets and megakaryocytes from 11 patients with the carcinoid syndrome have been studied by transmission electron microscopy. Cells fixed in phosphate-buffered glutaraldehyde are oval to discoid, with pseudopods, a dilated open-channel system, and a prominent dense tubular system as defined by peroxidase activity and alkaline bismuth stain. Atypical with hexagonal lattices and treaded substructures and large (diameter greater than 0.5 mum), phosphatase-positive, debris-containing vacuoles are four times more numerous than in normal platelets. Incubation of platelets in a 0.05% suspension of latex results in particle incorporation into phagosomes and the debris-containing vacuoles. Molybdate-dichromate stain reveals two classes of dense bodies, one of which (with a reticular core) is 20 times more numerous than in normal platelets. Bone marrow megakaryocytes lack both dense bodies and debris vacuoles analogous to those found in circulating platelets. These results suggest autophagy or endocytosis abnormalities and provide evidence for multiple types of dense bodies in carcinoid platelets.

Acid Phosphatase↗
PubMed1976

Phagocytosis in human platelets: localization of acid phosphatase-positive phagosomes following latex uptake.

Incubation of human platelets in plasma containing a suspension of latex particles for 1-90 min resulted in progressive accumulation of particles in the open-channel system, followed by localization of latex in electron-opaque vacuoles. After 60 min, acid phosphatase was localized within latex-containing vacuoles. The periodate-alkaline-bismuth reaction intensely stained external membranes and membranes of the open-channel system. Membranes of latex-containing organelles were not stained. Latex phagocytosis was independent of both anticoagulant choice and aspirin effects. Our results indicate that the platelet can act as a true phagocyte, and we suggest that the phagocytic process is chronologically similar to that reported for polymorphonuclear leukocytes.

Acid Phosphatase↗
PubMed1976

Ricinoleic acid effects on rabbit intestine: an ultrastructural study.

In fasting rabbits, segments of ileum and colon were perfused with ricinoleic acid. This fatty acid is the active principle of castor oil and stimulates intestinal fluid secretion. Biopsies taken from perfused segments were examined by electron microscopy after staining with lanthanum hydroxide and ruthenium red. These stains, which typically bind to extracellular surfaces, were used to assess the integrity of junctional zones between cells. In this study, ricinoleate did not alter ruthenium or lanthanum staining in junctional areas, a finding suggesting that ricinoleate does not cause fluid secretion by selectively disrupting these areas.

Animals↗
PubMed1975

Airsacculitis in the baboon.

A baboon (Papio anubis) that had been given opiate compounds through an indwelling catheter developed mucopurulent airsacculitis. After a prolonged course, the infection was eventually controlled by medical and surgical means. Air-sac involvement, though rarely reported in nonhuman primates, appeared frequently in the group of baboons to which this subject belonged--all of which were being treated experimentally with opiates. Proposed explanations for this unusual incidence included the propensity of opiates to induce a histamine response, almost continuous contamination of pathogenic bacteria in the indwelling catheters, and a suggested anatomic predisposition of the baboon larynx to drain secretions into the air sac.

Air Sacs↗
PubMed1975

Hemoprotozoa in mourning doves and other small birds of western Oklahoma.

Blood smears obtained from 370 birds live-trapped in western Oklahoma were examined for hemoprotozoa. Haemoproteus spp. were found in 189 (90.4%) mourning doves (Zenaida macroura), one oriole (Icterus galbula), two mockingbirds (Mimus polyglottos), and three brown thrashers (Toxostoma rufum). Plasmodium sp. was present in one brown thrasher. Haemoproteus spp. in the mourning dove were identified as H. sacharovi and H. maccallumi, with the latter species predominating. The average parasitemia for doves infected only with H. sacharovi was 0.1% of the erythrocytes, for doves infected only with H. maccallumi it was 0.9%, and in doves with dual infections 1.8% of the erythrocytes were infected.

Animals↗