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Biomedical subjects

J Tai

Publications and source records attributed to J Tai.

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

Successful intracerebral allotransplantation of pancreatic endocrine cells in spontaneous diabetic BB rats without immunosuppression.

An approach for pancreatic-islet transplantation in the spontaneous diabetic Bio-Breeding (BB) Wistar rat is described in which purified allogeneic pancreatic endocrine cells (PEC) are inoculated intracerebrally in the diabetic recipients. Without immunosuppression, 12/12 of the recipient animals responded to the transplanted PEC with no further need of insulin administration. Also, 8/12 showed normalization of nonfasting blood glucose (BG), 24-hour urine output, and gradual increase in body weight (BW) for a mean observation period of over 122.1 +/- 13.6 days. They had a glucose disappearance K rate of 1.7 +/- 0.3 (mean +/- SE), following intravenous (IV) glucose load. The grafted PEC remain functional and apparently are not affected by the usual immunorejection and/or original disease process during the whole period of observation. This achievement of long-term allograft function without immunosuppression would provide an opportunity to study the recurrence of diabetes and the effect of islet-cell transplantation in chronic diabetic complication in the spontaneous diabetic BB rat model which closely resembles human type 1 diabetes mellitus.

Animals↗
PubMed1984

Intracerebral allotransplantation of purified pancreatic endocrine cells and pancreatic islets in diabetic rats.

Allogeneic pancreatic endocrine cells (PEC) and whole islets from inbred Lewis (AgB 1/1) and outbred Wistar rats were implanted intracerebrally (i.c.) into two designated areas of streptozotocin-induced diabetic ACI (AgB 4/4) rats across the major histocompatibility barrier. All the transplants of PEC from Lewis (n = 12) and Wistar (n = 7) donors remained functional for an observation period in excess of 200 days. In contrast, only 3/6 Lewis and 3/9 Wistar whole-islet transplants were able to maintain function for a prolonged period. Recipients with functional PEC or islet allografts had normalized nonfasting blood glucose (BG) in the 24-hr. BG profile, and they maintained a steady body weight gain. ACI recipients of PEC from Lewis rats had glucose disappearance K rates of 1.3 +/- 0.3 (mean +/- SE) and a normal basal BG level in 4 hr following the i.v. glucose load. Histological section of the brain tissues with successful i.c. islet or PEC grafts up to a duration of 5 1/2 months revealed healthy endocrine cells in the cortex and the subarachnoid space. These grafts were permeated with capillaries but devoid of exocrine tissues or lymphoid cell infiltration. These observations suggest that the brain is an immunologically privileged site, and that it is a hospitable site for the pancreatic endocrine cell suspension. However, the immunological protection offered to allogeneic transplants by the brain is incomplete, and purified PEC must be employed to ensure consistent long-term allograft survival.

Animals↗
PubMed1983

Inhibition of pulmonary metastases of B16 melanoma with irradiated tumor cells and BCG.

When the tumor-bearing leg of C57BL/6J mice was amputated 16 days after SC inoculation of 10(6)B16 melanoma cells, all the amputated mice died of pulmonary metastases. Transfer of lungs from the amputated to normal syngeneic mice revealed tumor cells in the lungs just after amputation. Repeated weekly injections of BCG and irradiated tumor cells, beginning 24 h after amputation of the tumor-bearing limb, prolonged the survival only of mice presensitized to BCG. Injections of BCG or irradiated melanoma cells alone, or neuraminidase- and mitomycin C-treated tumor cells or of Levamisole had no effect, but injections of ConA-coated tumor cells slightly prolonged the survival of the amputated mice. Both BCG and B16 cells induced humoral and cell-mediated immunity but there was no cross-reactivity between BCG and B16 cells.

Animals↗
PubMed1983

Successful intracerebral allotransplantation of purified pancreatic endocrine cells in diabetic rat.

Single pancreatic endocrine cells (PEC) have been demonstrated to restore normoglycemia when transplanted intracerebrally in diabetic rat recipients across a major histocompatibility barrier without immunosuppression. Twelve out of twelve transplants of purified PEC have achieved long-term survival of over 176 days. This approach would provide a model to identify the specific cell(s) as inducer of graft rejection and an opportunity for transplantation study in spontaneous diabetic BB rats and larger diabetic animal models.

Animals↗
PubMed1980

Studies with implantable artificial capillary units containing rat islets on diabetic dogs.

An implantable artificial endocrine pancreas consisting of a coiled single acrylic copolymer capillary surrounded by a rat islets (1000/kg body weight) was implanted in 10 streptozotocin-alloxan diabetic dogs. About 5 h following implantation plasma glucose decreased from an initial mean value of 350 mg/dl to 150 mg/dl, and then to 100 mg/dl at 12 h. Plasma insulin increased to a mean of 39 mU/1 (range 23-83 mU/l) at 5 h in the recipient animals In addition a much improved plasma glucose disappearance rate (K = 1.9 plus or minus 0.3) with slightly delayed insulin responses was seen after intravenous glucose tolerance tests performed in 4 dogs at 7, 8, 10 and 18 h following implantation. These findings suggest that xenogeneic rat islets implanted as an artificial endocrine pancreas can improve glucose metabolism in the diabetic dog.

Animals↗
PubMed1980

In vitro culture--a method of pancreatic islet preservation for transplantation.

Pancreatic islets from adult rats, accumulated daily for a period of 2 wk, were cultured in artificial capillary culture units that were perfused with nutrient medium. Viability and functional capacity of these islets in this in vitro culture system has been shown to be maintained. The therapeutic efficiency of cultured islets was comparable to freshly isolated islets when assessed by transplantation into streptozotocin-induced diabetic rats. Intraportal implantation of either freshly isolated or cultured islets into isogeneic diabetic rats resulted in normal weight gain as well as complete reversal of hyperglycemia, glycosuria, and polyuria in the diabetic rat recipient. The normoglycemic state was sustained for more than 12 mo. Plasma glucose clearance rate (KG) were significantly lower in both the transplanted fresh or cultured islet groups than in the normal controls; however, the cultured islets were not less effective than the fresh islets. The results of the present study indicate the feasibility of accumulation of large numbers of islets in the in vitro culture system without any loss of therapeutic efficiency when implanted in vivo. Further improvement of this in vitro culture system can thus be applied in islet preservation for islet transplantation.

Animals↗
PubMed1980

Streptococcal infection in young pigs. V. An immunogenic polysaccharide from Streptococcus suis type 2 with particular reference to vaccination against streptococcal meningitis in pigs.

Of 17 pigs vaccinated with STreptococcus suis type-2 capsular polysaccharide plus Freund's Incomplete Adjuvant, all developed opsonizing antibody against Str. suis type 2. Of 14 pigs vaccinated with type-2 polysaccharide alone, 4 (possibly 6) developed opsonizing antibody. It is possible that some pigs vaccinated with polysaccharide plus Freund's Incomplete Adjuvant developed opsonizing antibody in response to a 'booster' injection of polysaccharide alone. Of 21 unvaccinated control pigs, late bleeding from 3 showed opsonizing activity against Str. suis type 2.

Animals↗
PubMed1979

Production and characterization of xenogeneic antisera to a human renal cell carcinoma-associated antigen.

Antisera to human renal cell carcinomas were produced by the immunization of goats and rabbits with dissociated tumor cells and/or tumor homogenates from single donors. After absorptions with human red blood cells and homogenates of human liver, lung, spleen, and heart, all the immune sera reacted on immunofluorescence with the brush border of the proximal convoluted tubules of adult and fetal human kidneys and with the proximal convoluted tubular epithelia of rabbits, guinea pigs, rats, and mice. After further absorption with pooled normal human kidney homogenates, the immune sera on immunofluorescence showed cytoplasmic staining of smears and sections of 21 of the 22 human renal cell carcinomas tested. These sera did not show any staining of normal adult human tissues including normal kidney adjacent to the carcinomas, perirenal fibroblasts and peripheral blood leukocytes from the patients, human fetal kidneys, transplanted renal adenocarcinoma of BALB/c mice, and several human tumors tested, i.e., transitional cell carcinoma of the bladder, adenocarcinomas of the breast and colon, squamous cell carcinoma of the lungs, malignant lymphoma, and melanoma. Autoradiography of tissue sections with 131I-labeled antitumor globulins revealed greater localization of radioactivity in tumors than in adjacent normal kidney. Membrane immunofluorescence with the immune sera rendered tumor-specific after appropriate absorptions revealed tumor-associated antigens on the surfaces of all 5 human renal carcinoma cell lines tested.

Adenocarcinoma↗