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J G Sharp

Publications and source records attributed to J G Sharp.

At least 37 records · Page 2Linked to original sources
PubMed1989

Characteristics of submucosal lymphoid tissue located in the proximal colon of the rat.

In this study we have examined the morphology and steroid sensitivity of proximal colonic lymphoid tissue in the Fisher 344 rat. A time course study was conducted in which groups of animals were injected subcutaneously with hydrocortisone sodium succinate (125 mg/kg body weight) and killed on Days 0-4. Thymus, jejunal and ileal Peyer's patches and proximal colonic lymphoid tissue were excised, weighed and processed for histological analysis. The results showed that the maximum cytoreductive effects of the hydrocortisone were evident on Day 2. Thymus and proximal colonic lymphoid tissue weight decreased to 5 and 18% of the control values respectively, before returning towards control values over the next two days. In contrast, jejunal and ileal Peyer's patch weights were unaltered. A dose response experiment was conducted using the same endpoints. Rats were injected subcutaneously with hydrocortisone at 60, 120, 200 and 300 mg/kg body weight and killed on Day 2. The results of this experiment showed that the proximal colonic lymphoid tissue, like thymus, responded with a dose-dependent loss of tissue weight. The spleen and Peyer's patches showed only a slight weight decrease compared to the control. These data showed that the response of proximal colonic lymphoid tissue to steroids was more similar to that of thymus, a primary lymphoid tissue, than to other secondary lymphoid tissues. Finally, grafts of fetal proximal colon under the kidney capsule of syngeneic adults supported the development of this lymphoid aggregate in the absence of luminal antigenic stimulation. These results suggest that the development and functional contribution of proximal colonic lymphoid tissue to the immune system warrants a more detailed examination.

Animals↗
PubMed1989

Apparent synergism between radiation and the carcinogen 1,2-dimethylhydrazine in the induction of colonic tumors in rats.

We have evaluated the interaction of radiation and 1,2-dimethylhydrazine (DMH) with respect to colon carcinogenesis in the Fischer 344 rat and have demonstrated the utility of this model for future more detailed mechanistic studies. In initial experiments, single doses of abdomen-only radiation (9 Gy) or DMH (150 mg/kg) were employed alone or in combination. Radiation was administered 3.5 days prior to the DMH. At 8 months post-treatment, the incidence of DMH-induced colon tumors was doubled by prior radiation exposure. When the protocol was repeated employing a DMH dose of 135 mg/kg with a 6-month observation period, the incidence of tumors induced by DMH alone was reduced, but the combination of radiation plus DMH still resulted in an augmentation of tumor incidence. When the protocol of radiation plus DMH was repeated three times at monthly intervals, a 15-fold increase in tumor incidence (from 5 to 74%) was observed at 6 months post-treatment. This finding demonstrates an apparent synergy between the radiation and the chemical carcinogen. Throughout these studies, the appearance of carcinomas was associated with preexisting colonic lymphoid nodules. The reproducibility of tumor induction as well as range of tumor incidence generated by variations in this system may be adequately sensitive to examine the combination of much lower doses of radiation and/or chemical carcinogen. The relationship between existing lymphoid aggregates which alter local epithelial cell kinetics and which are associated with fenestrations in the basement membrane, and the development of colon cancer in congruent sites may assist in defining dose-response curves for combined agents as well as providing a system for evaluating the mechanisms underlying their interactions.

Adenoma↗
PubMed1988

Characterization of proximal colonic lymphoid tissue in the mouse.

Here we describe a nodule of lymphoid tissue which was consistently located in the proximal colon of mice approximately 25% of the distance from the cecum to the rectum. Immunohistochemical characterization of this nodule demonstrated that the majority of lymphocytes were relatively immature 14.8+ (B220+), IgM+, Ia+ (specificity 20) B cells some of which were also Ly-1+. These nodules also possessed an occasional T cell (Thy-1+, Ly-1+, Lyt-2+) aggregate at the periphery. Rare, small areas did not stain for either T or B cell markers. These lymphoid nodules were associated with epithelial cells which stained positively with the ER-TR4 monoclonal antibody (which also recognizes thymic cortical epithelial cells) and also with ER-TR6, which has been reported to recognize thymic macrophages or dendritic cells. The overlying colonic epithelium stained intensely with the ER-TR4 monoclonal antibody. Proximal colonic lymphoid tissue was extremely sensitive to steroid treatment, losing approximately 80% of its mass within 24 hours in response to a single intraperitoneal injection of 2 mg hydrocortisone acetate. This response was similar to that of the thymus and to that reported for the bursa of Fabricius, but unlike that of other gastrointestinal lymphoid aggregates. These results indicated that proximal colonic lymphoid tissue contains a high frequency of relatively immature B cells and may be a primary site of their generation, possibly including some of the Ly-1+ phenotype. These observations correlate with new evidence suggesting that the allantois participates in the formation of the distal midgut, including its lymphoid components.

Animals↗
PubMed1988

Difluoromethylornithine inhibits urogastrone stimulation of neomucosal growth.

Urogastrone (UG) stimulates the growth of intestinal neomucosa on patched intestinal defects. This effect may be dependent on increased polyamine biosynthesis. The aim of this study was to determine if difluoromethylornithine (DFMO), a specific inhibitor of polyamine synthesis, would inhibit urogastrone stimulation of neomucosal growth. Twenty-four New Zealand white rabbits (2.1-2.9 kg) had 2 x 5-cm ileal defects patched with adjacent cecal serosal surface. Group I (n = 6) served as controls. Group II (n = 6) received UG 1.5 micrograms/kg/hr subcutaneously. Group III (n = 6) took 2% DFMO orally. Group IV (n = 6) received the same doses of UG and DFMO simultaneously. Animals were sacrificed 7 days after patching to assess neomucosal growth. Urogastrone infusion resulted in significantly greater neomucosal coverage (54 +/- 4%) and neomucosal surface area (236 +/- 18 mm2) in the Group II animals. Neomucosal coverage and contraction of the intestinal defects and neomucosal surface area were similar in the other three groups. Crypt cell production rate (15.5 +/- 2.0 cells/hr) and disaccharidase activity were also significantly greater in Group II than in the other groups. DFMO alone (Group III) resulted in a significantly lower ornithine decarboxylase (ODC) activity, polyamine content, and crypt cell production rate. Group IV animals had lower ODC activity but not lower polyamine content or crypt cell production rate. UG resulted in a significant increase in neomucosal growth. DFMO prevented this stimulatory effect and inhibited ornithine decarboxylase activity. The stimulation of neomucosal growth by UG is dependent, at least in part, on increased polyamine biosynthesis.

Animals↗
PubMed1988

Intestinal glucose uptake is increased in aged mice.

Carbohydrate metabolism is impaired in the aged. Whether this is related to impaired glucose uptake or to other factors remains unclear. We measured changes in proliferative activity, glucose uptake, and disaccharidase activity in the intestinal mucosa of mice aged 2, 12, 24, and 30+ months to evaluate glucose absorption and its relationship to intestinal structure and proliferative activity. In vitro glucose uptake was increased significantly in the 30+ month-old mice compared to the younger animals. Similarly, crypt cell production rate and thymidine uptake were also increased. However, there were no significant changes in intestinal weight and length and villus height and crypt depth. These findings suggest that altered carbohydrate absorption in the aged is related to factors other than diminished mucosal glucose uptake. Whether this increased function is related to structural changes in the gut remains unclear.

Aging↗
PubMed1988

Preferential in-vitro growth and expansion of leukemic T lymphoblasts.

An in-vitro culture system was used to selectively grow malignant cells from the bone marrow of a patient with acute T-lymphoblastic leukemia. Molecular analysis of DNA extracted from the bone marrow cells before culture showed the presence of both rearranged and germ line patterns for the T-cell beta receptor (CTB) gene, and chromosomal analysis revealed the presence of a major and a minor abnormal clone. The cells were cultured in RPMI medium supplemented with 20% fetal calf serum, 2% lymphocyte conditioned medium, L-glutamine and antibiotics. The presence of malignant cells in the cultured population was confirmed by morphologic, molecular probing and cytogenetic analysis. After four weeks in culture, DNA extracted from the cultured cells showed only the rearranged pattern for the CTB gene. Chromosomal analysis of the same cultured sample revealed only the presence of the initially predominant abnormal clone. Shortly thereafter, analysis of fresh uncultured bone marrow cells from the patient in relapse revealed that the same chromosomally abnormal clone also predominated in vivo. Thus, our results demonstrate the selective nature of this culture system and its ability to amplify leukemic T-lymphoblasts. This culture system is also useful for detecting occult malignant cells in histologically normal bone marrow.

Adult↗
PubMed1988

Effect of urogastrone on intestinal regeneration is dose-dependent.

Urogastrone (UG) increases the rate of intestinal regeneration in intestinal defects patched with adjacent serosal surfaces by increasing the rate of epithelial cell migration and proliferation. It also inhibits contraction of the patched intestinal defect. The purpose of this study was to determine the effect of the dose of UG on these processes. Twenty male New Zealand white rabbits (1.9-2.9 kg) had 2 x 5 cm ileal defects patched with adjacent caecal serosal surface. Group I (n = 6) served as the control group. Group II (n = 5), Group III (n = 5) and Group IV (n = 4) received UG 0.15, 1.5 and 4.5 micrograms/kg/h i.v. via mini-osmotic pumps. Seven days after patching, both epithelialization of the patched defect and neomucosal surface area were significantly increased by UG and the increases were dose-dependent. Contraction was not inhibited by the lowest dose of UG but was diminished by 1.5 micrograms/kg/h. Proliferative activity in both neomucosa and adjacent normal mucosa were increased in UG-treated animals with the greatest increase in rabbits receiving 1.5 and 4.5 micrograms/kg/h UG. The effect of UG on both epithelialization and contraction of patched intestinal defects is dose-dependent. Since the lowest dose of urogastrone increased epithelialization without increasing proliferative activity, stimulated cell migration appears to be the earliest effect of UG.

Animals↗
PubMed1988

Effects of differentiation inducing chemicals on in vivo malignancy and NK susceptibility of metastatic lymphoma cells.

In the present investigation we have determined the effects of the differentiation-inducing chemicals dimethyl sulfoxide (DMSO) and sodium butyrate on the growth and tumorigenicity of a highly malignant/metastatic cell line (RAW117-H10) and its less tumorigenic parental lymphoma cell line (RAW117-P). Both of these agents at doses shown to be nontoxic slowed the growth of these cells in suspension culture and significantly lengthened the doubling time while reducing colony formation in the agar tumor stem cell assay. Corresponding to these observations, the in vivo tumorigenicity of the highly malignant RAW117-H10 line was reduced by both chemicals but particularly by butyrate treatment. In addition, both agents increased the expression of some glycoproteins and the glycolipid asialo GM1. There was also a corresponding increase in the NK susceptibility of the normally NK resistant RAW117-H10 cells. To determine if the decreased malignancy of the highly malignant cells following treatment with the chemical agents was primarily due to the alteration in cell surface glycoconjugates or merely due to concomitant decreased growth potential, we transplanted highly glycosylated membrane fragments from normal syngeneic thymocytes to both RAW117-P and RAW117-H10 cells using a Sendai virus mediated membrane fusion technique. The in vivo tumorigenicity of the membrane altered RAW117-H10 cells was significantly decreased. These results strongly suggest that the decreased in vivo malignancy of RAW117-H10 cells resulting from treatment with chemical differentiation agents is caused by their increased susceptibility to NK cell mediated lysis which in turn results from cell surface changes involving altered, primarily increased, expression of certain glycosylated surface molecules. The cell surface glycoconjugates, such as receptors for certain lectins and glycolipid asialo GM1, can be used as markers for malignant potential and NK sensitivity of malignant lymphoid cells.

Animals↗
PubMed1987

Cell surface properties associated with malignancy of metastatic large cell lymphoma cells.

The highly malignant and metastatic RAW117-H10 cell line was developed by in vivo selection from the Abelson leukemia virus induced parental RAW117-P lymphoma. In this study we have characterized these cell lines with regard to their expression of lymphocyte and macrophage differentiation antigens, adherence, phagocytic properties, binding of various lectins, binding of antibodies to glycolipid asialo-monoganglioside, and the role of butanol extractable cell surface molecules to determine if any of these cell surface properties are associated with the malignant potential of RAW117-H10 cells. The only major difference in immunological phenotypes between RAW117-P and RAW117-H10 cells was an increased expression of Thy-1 molecules by the latter. However, the highly malignant RAW117-H10 cells bound significantly less concanavalin A, Ricinia communis agglutinin, succinylated wheat germ agglutinin, and particularly anti-asialomonoganglioside than their parental counterpart and were resistant to natural killer cell mediated cytolysis. Removal of butanol extractable cell surface molecules significantly decreased the malignancy of RAW117-H10 cells and increased their susceptibility to natural killer cell mediated cytolysis. The butanol treated RAW117-H10 cells regained high in vivo malignancy when recultured for 3 days to permit regeneration of their cell surface components. The butanol extracted RAW117-H10 cells still expressed high levels of Thy-1 indicating that this most probably represented "inappropriate" antigen expression. Since the expression of lymphocyte differentiation antigens did not correlate with the malignant behavior of the cells, we postulate that these antigenic differences merely represent phenotypic variation. The decreased malignant potential of the butanol treated RAW117-H10 cells did correlate with increased cell surface anti-asialomonoganglioside binding (glycolipid) and increased natural killer cell susceptibility.

Animals↗
PubMed1987

Stimulation of neomucosal growth by systemic urogastrone.

Patching small intestinal defects with colon serosa results in the growth of functional neomucosa. However, the rate of neomucosal growth is slow and the defect contracts markedly. The aim of this study was to determine if systemic urogastrone would enhance neomucosal growth. Twenty-two New Zealand white rabbits had two 2 X 5-cm ileal defects patched with colon serosa and osmotic pumps placed subcutaneously. Eleven animals had saline infused at a rate of 5 microliter/hr. The other eleven rabbits had urogastrone (1 mg/ml saline) infused at the same rate. One animal died in this group. There was a modest increase in neomucosal growth after 2 weeks of urogastrone infusion. Three weeks after patching, defect coverage was significantly greater in the urogastrone group (99.8 +/- 0.1 vs 96.0 +/- 1.2%, P less than 0.005) and more defects were completely covered by neomucosa (6/10 vs 1/12, P less than 0.05). Less contraction occurred in the urogastrone group (46 +/- 2 vs 35 +/- 3% initial defect, P less than 0.005) and resultant neomucosal surface area was greater (361 +/- 12 vs 266 +/- 20 mm2, P less than 0.0005). In vitro glucose uptake was significantly greater in the urogastrone group but disaccharidase and diamine oxidase activity were similar. Crypt cell production rate was significantly greater 2 weeks after operation compared to 3 weeks in both groups and was greater in the urogastrone group compared to the saline group at 2 weeks (24.9 +/- 1.1 vs 20.1 +/- 1.1, P less than 0.02). Systemic urogastrone enhances neomucosal growth by increasing the rate of growth and diminishing contraction.(ABSTRACT TRUNCATED AT 250 WORDS)

Amine Oxidase (Copper-Containing)↗
PubMed1987

Differential growth characteristics of low and high metastatic variant RAW117 murine lymphosarcoma cells.

The Abelson-virus-induced murine lymphosarcoma cell line RAW117-P and its in vivo selected highly malignant and metastatic variant RAW117-H10 have been studied for their growth in vivo, in vitro and in semi-solid agar. The highly malignant metastatic variant RAW117-H10 cells killed syngeneic Balb/c mice rapidly and formed 100-200 times more gross liver tumor nodules than the less malignant parental RAW117-P cells. On the other hand, there were no differences between the in vitro growth kinetics of these cells as measured by various parameters such as metaphase arrest or cells in DNA synthetic phase on various days after the initiation of the culture. These cells could be grown in semi-solid agar and formed characteristic colonies. The parental cells formed many very small colonies, whereas the highly malignant cells formed fewer, but very large colonies in soft agar. These results suggest that differential interactions of highly malignant RAW117-H10 cells with the host, particularly the host immune system, are much more important for regulating the number of metastases than any intrinsic growth advantages. It appears that growth differences, potentially based on lack of response to feedback inhibition rather than on kinetic parameters, are responsible for highly malignant RAW117-H10 cells forming larger colonies both in agar in vitro and in the liver in vivo.

Animals↗
PubMed1987

Detection of malignant cells in histologically normal bone marrow using culture techniques.

Cellular material retained on screens used to filter aspirated bone marrow for future autologous marrow transplantation was studied using long-term culture techniques in 20 consecutive patients. All patients had marrow aspirate and biopsy specimens that were normal histologically. Cultures from five patients grew malignant cells similar to those of the known underlying malignancy. Two types of culture methods were used in these studies. Method I consisted of a long-term bone marrow culture system which predominantly favors adherent cells, and Method II consisted of a suspension type culture system favoring expansion of mononuclear cell types. These findings suggest that tumor cells are reinfused more often at the time of autologous bone marrow transplantation than has been previously suspected. Although the clinical significance of these findings is not known, it is clear that culture techniques combined with special stains and molecular probing will allow the improved detection of occult tumor cells in bone marrow from patients undergoing autologous marrow transplantation. These observations emphasize the need for a comprehensive study of histologically normal autologous marrow using culture techniques to determine the frequency of occult involvement by viable malignant cells and the clinical implications of these findings.

Adult↗
PubMed1987

Stem and stromal cell reconstitution of lethally irradiated mice following transplantation of hematopoietic tissue from donors of various ages.

If the limited life span of hematopoietic tissues in vitro is due to a finite proliferative capacity of individual stem cells, one might expect tissues of young donors to possess a greater proliferative capacity and to contain a larger population of primitive stem cells than those of older donors. To test this hypothesis, we used 12- and 8-day spleen colony formation (CFU-s) to assay more and less primitive stem cell subpopulations of three murine hematopoietic tissues: fetal liver (FL) and weanling (WBM) and adult (ABM) bone marrow. Subsequently, the same assays and a stromal cell assay were performed on the bone marrow from groups of lethally irradiated mice reconstituted with these tissues. Comparison of the CFU-s content of the donor tissues revealed that FL contained a significantly greater proportion of primitive stem cells as evidenced by a (Day 12):(Day 8) CFU-s ratio of 3.0 +/- 1.0 as compared to 0.9 +/- 0.1 for WBM and ABM. In addition, at 21 weeks post-transplantation the CFU-s/femur values of the FL reconstituted group were significantly greater than those of the ABM and WBM reconstituted groups. These results suggest that fetal hematopoietic tissue contains a greater proportion of primitive stem cells and has a greater proliferative potential than hematopoietic tissue from older donors. No differences were seen in stromal cell reconstitution of the three experimental groups. In all cases, assayable fibroblast colony forming cells (CFU-f) remained at 20-40% of control values, even at 21 weeks postreconstitution.

Aging↗
PubMed1987

Ontogeny and regulation of the immune system.

Classic studies in embryology and contemporary research in immunology and molecular biology have disclosed the carefully orchestrated events leading to development of the immune system and immunoregulation that ultimately provide immunohomeostasis. During ontogeny, the pluripotential stem cell emerges and differentiates into all hematopoietic lineages, including three major immunologically relevant components: T-cell differentiation occurs within the thymus; B cells appear within fetal liver, adult bone marrow, and possibly other abdominal sites; and concurrently, the monocyte-macrophage system develops. Under the influence of an array of cytokines and cellular interactions, immune regulation is established. T and B lymphocytes elaborate genetically encoded messages that acquire specificity via transposable genetic elements. Receptors and cytokines provide immune recognition, communication, regulation, and memory for antigens. Inherited and acquired defects in ontogeny and immune regulation are the basis for immunodeficiency disorders.

Animals↗
PubMed1985

Comparison of the intravenous and intraperitoneal routes of administration of tritiated thymidine in studies of cell production in the gastrointestinal tract of the rat.

Incorporation of 3H-Thymidine into DNA-synthesizing cells of the gastrointestinal tract of the rat was examined following administration of the isotope by intraperitoneal and intravenous routes. Estimates of whole tissue incorporation expressed as DPM/mg dry weight and of proliferating cells expressed as DPM/crypt or gland in the different segments of the gut indicated no differences in the degree of 3H-TdR uptake into DNA following intraperitoneal or intravenous routes of administration. The possibility of misdirected I.P. injections was examined following injection of 3H-TdR into the cecum or bladder. DPM/mg wet weight of gastrointestinal tissues indicated reduction in the uptake of 3H-TdR into DNA of intestinal tissues following intracecal and intrabladder administration of 3H-Tdr. The intraperitoneal route of administration of 3H-TdR appears to be equally effective in the distribution of the isotope into different segments of the gut when compared to the intravenous route and is a more convenient method in studies of cell production in the gastrointestinal tract of the rat.

Animals↗
PubMed1985

Late ultrastructural effects of heavy ions and gamma irradiation in the gastrointestinal tract of the mouse.

The irradiated gastrointestinal tract of LAF1 mice was examined one year following a single dose (1000 rad) of either 12C heavy ions or 60Co gamma rays. Qualitative ultrastructural analysis of the gastrointestinal tract of mice exposed to heavy ions or gamma irradiation did not show any discernible differences. In the stomach of irradiated mice, parietal cells contained numerous lysosomes; the gastric chief cells occasionally contained myelin figures. The epithelial cells of the small intestine, especially jejunum and ileum, showed several changes: (1) increased vacuolation was seen both inter- and intra-cellularly, (2) epithelial cell projections penetrated the basal lamina and were in contact with underlying mesenchymal cells, (3) occasional Paneth cells contained intracellular vacuoles consisting of fibrillar and granular material. In the large intestine occasional signs of degeneration were observed. Qualitative analysis of stromal elements of the gut in irradiated mice indicated the presence of damage to capillary endothelial cells, smooth muscle cells and some nerve processes. The amount of basement membrane (BM) around capillaries and small vessels was increased; the same phenomenon was observed to affect the nerve processes, but with less severity. Quantitative analysis of the basement membrane thickness around capillaries in irradiated vs. control mice showed significant differences. Basement membrane thickness around capillaries in the gastric mucosa and duodenum did not differ significantly in any of the treatment groups. In jejunum, the gamma treated animals exhibited significantly higher BM thickness when compared to unirradiated controls. In ileum, only 12C-heavy ion treated animals showed thicker BM when compared to their respective controls. In colon, both 12C- and 60Co-treated animals showed increased BM thickness when compared to controls.

Animals↗