Ways of influencing tenderness in meat.
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In Vitro Techniques↗
Biomedical subjects
J G Sharp
Publications and source records attributed to J G Sharp.
Extent and role of urogastrone in the adaptive response of rat intestine to patching of a surgical defect in the ileum.
Crypt cell production rate, morphometric changes and uptake of radiolabeled human urogastrone (125I rhUG) were evaluated in intestinal tissues of the rat at 2, 4, 8, and 12 days following patching of a surgical defect in the ileum with adjacent cecum. The terminal ileum was incised along its antimesenteric border and the margin of the opened ileum was sutured onto the serosal surface of the cecum. At autopsy, the animals were injected intraperitoneally with 1 microgram/g body weight of the metaphase arrest agent, vincristine sulfate, and 50 microCI of 125I-rhUG (specific activity 1.7 microCi/micrograms) to quantify the crypt cell production rate and uptake of radiolabeled urogastrone, respectively. The results indicated that the crypt cell production rate was increased significantly throughout the small intestine of operated animals till the 12th postoperative day as compared to unoperated rats. The colon showed significantly increased crypt cell production rate only on the 4th day after surgery compared to unoperated rats. The stomach showed no changes. The uptake of 125I-rhUG increased significantly on the 2nd and 4th postoperative days in the small intestine and on the 2nd postoperative day in the colon as compared to unoperated rats and gradually decreased with increasing time after surgery. These results suggest that patching of an ileal defect resulted in a strong compensatory response in the small intestine. These results also demonstrated a close association between epithelial cell proliferation and uptake of 125I-rhUG, particularly in the early part of intestinal adaptation following the surgical stimulus to ileum.(ABSTRACT TRUNCATED AT 250 WORDS)
Adaptation, Physiological↗
Role of organized intestinal lymphoid aggregates in intestinal regeneration.
Intestinal lymphoid tissue has a complex interrelationship with the epithelium. The epithelia of intestinal crypts associated with lymphoid aggregates have an increased proliferation rate. In the present study, the authors tested the hypothesis that organized intestinal lymphoid tissue (Peyer's patches) enhances intestinal regeneration by studying this process with and without an adjacent Peyer's patch. Forty adult male Sprague-Dawley rats had full-thickness ileal defects patched with cecal serosa to allow regeneration of ileal mucosa. Control animals (group I) had the patch constructed adjacent to a Peyer's patch, whereas this Peyer's patch was excised in group II. Intestinal regeneration in both groups was evaluated on the third, fifth, seventh, and ninth days after operation. During the early phase of regeneration, both epithelial cell proliferation and migration were decreased in the patched defect after excision of the Peyer's patch. Crypt cell production rate in the adjacent normal mucosa also was decreased after excision of the Peyer's patch. Excision of the Peyer's patch resulted in less well-developed crypts and villi. Wound contraction, however, was greater in the intestinal defect adjacent to the Peyer's patch until day 7. In conclusion, Peyer's patches have a facilitative effect on the healing of intestinal wounds by promoting both epithelial cell migration on the defect and epithelial cell proliferation in the crypts adjacent to the wound and by decreasing the rate of wound contraction. These findings support a role for intestinal lymphoid tissue in the regulation of epithelial cell maintenance.
Animals↗
Establishment, characterization and determination of cell surface sugar receptor (lectin) expression by neoglycoenzymes of a human myeloid marker-expressing B lymphoblastoid cell line.
Mediation of cellular interactions by protein (lectin)-carbohydrate recognition presupposes the expression of respective surface determinants. Due to the importance of cellular contacts between bone marrow stromal cells, recently shown to express cell surface lectins, and tumor or normal progenitor cells for biosignaling and marrow egress, quantitation of cell surface sugar receptor expression by a panel of chemically glycosylated enzymes (tetrameric E. coli beta-galactosidase) for human leukemia/lymphoma cells was initiated. Cells of the new B lymphoblastoid line Croco II that are partially positive for the CD15-specific epitope expressed receptors for various sugar specificities on their surface, fulfilling an indispensable prerequisite for establishment of glycobiological interactions. Binding studies with increasing neoglycoenzyme concentrations up to saturation in four cases disclosed values for apparent affinity constants in the range of 25-200 nM with 0.25-3 x 10(5) bound probes per cell. The presence of receptors for constituents of carbohydrate chains of cellular glycoconjugates was also ascertained biochemically, namely for beta-galactosides, alpha-mannosides, alpha-fucosides and N-acetylgalactosaminides. Expression of this property was modulated by changes in the culture conditions, as revealed by binding studies with cells, derived from growth in medium containing different serum concentrations. These findings indicate that cell surface sugar receptors of tumor cells warrant further attention with respect to recognitive interactions.
Antigens, CD↗