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Biomedical subjects

J Tai

Publications and source records attributed to J Tai.

At least 91 records · Page 5Linked to original sources
PubMed1978

Tyrosine aminotransferase from chick liver. Heat activation and cold inactivation of the enzyme.

The reversible heat activation and cold inactivation of tyrosine aminotransferase (L-tyrosine:2-oxoglutarate aminotransferase, EC 2.6.1.5) of chick liver were investigated. When the enzyme obtained by gel filtration was preincubated at 37 degrees C for 10 min with 50 micrometer pyridoxal 5'-phosphate (pyridoxal-5'-P), a 7-fold increase in enzyme activity was detected. When the preincubated enzyme was cooled to 0 degrees C, it lost its activity. Furthermore, the dramatic cyclical changes in enzyme activity occurred by sequential heating at 37 degrees C and cooling to 0 degrees C of the enzyme, in the presence of pyridoxal-5'-P, over shorter periods of time without loss of enzyme activity. However, when alpha-ketoglutarate was added to the enzyme during cold exposure, no further decrease in activity was observed. This protective effect was seen at a concentration of 5 muM.

Animals↗
PubMed1978

Radionuclide imaging of metastases from renal-cell carcinoma by 131I-labeled antitumor antibody.

On immunofluorescence assay, goat antisera reacted with renal-cell carcinomas from 20 patients, but not with adult normal human tissues (including patient's normal kidney). After in travenous injection, the 131I-labeled antibody localized preferentially in metastatic renal carcinoma in 6 consecutive patients. Labeled antitumor antibodies may have the specificity for tumor imagining which current radiopharmaceuticals lack.

Adenocarcinoma↗
PubMed1977

Immunochemotherapy of malignant melanoma with chlorambucil-bound antimelanoma globulins: preliminary results in patients with disseminated disease.

Thirteen consecutive patients with inoperable recurrent malignant melanoma were treated by immunochemotherapy with the use of chlorambucil noncovalently bound to goat or rabbit antihuman melanoma globulins. The next consecutive 11 patients fulfilling the criteria for admission into this study were treated with chemotherapy only, i.e., dimethyltriazenoimidazole carboxamide (DTIC). Follow-up was for a minimum of 29 months or until death. Two patients showing an objective response to immunochemotherapy had disease confined to lymph nodes and cutaneous sites; 5 others showed stabilization of cutaneous, nodal, and visceral disease, and 6 patients showed progression of their disease. The median survival of the responders and stabilizers was 20 months, but only 3.5 months for patients with disease progression. None of the 11 patients treated with DTIC had objective tumor regression, and all died within 11 months of the start of treatment with a median survival of 3 months. Immunochemotherapy significantly prolonged the survival compared to that in the DTIC-treated group (P less than 0.05). No hematologic or renal toxicity was detected after immunochemotherapy, but 2 patients in this group developed anaphylactic reactions. Skin reactivity tests to dinitrochlorobenzene and purified protein derivative were of no prognostic value

Adolescent↗
PubMed1976

Active immunoprophylaxis and immunotherapy in two mouse lymphoma models.

Injections of appropriate numbers of irradiated tumor cells produced antibodies against tumor cell-surface antigen(s) in both syngeneic tumor models studied: the early transplant generations of the spontaneous L2 lymphoma in AKR/J mice and the chemically induced EL 4 lymphoma in C57BL/6J mice. No antibody was detected in normal or nonimmunized tumor-bearing mice. Tumor inhibitory or enhancing activity was not demonstrated by these antibodies. Immunoprophylaxis or cell-mediated immunity against the L2 lymphoma was not observed after injections of irradiated L2 cells and/or BCG into AKR mice. However, injections of irradiated EL 4 cells alone were effective in immunoprophylaxis against as many as 10(6) EL 4 cells and in immunotherapy against 10(2) EL 4 cells per mouse. The addition of BCG injections made immunotherapy with irradiated EL 4 cells effective against a load of 10(4) EL 4 cells/mouse, though BCG alone was not effective for immunoprophylaxis against EL 4 cells. Resistance to EL 4 could be transferred with viable syngeneic peritoneal or nucleated spleen cells. In both tumor models, an ongoing delayed hypersensitivity reaction to BCG alone apparently did not inhibit bystander tumor cells even when tumor cells were mixed before inoculation with viable BCG. In neither tumor model were concanavalin A-coated tumor cells more potent for immunoprophylaxis than were irradiated tumor cells alone.

Animals↗
PubMed1975

Antibody as carrier of 131I in cancer diagnosis and treatment.

Cell-surface localizing heterologous antibodies against mouse EL4 lymphoma, Ehrlich ascites carcinoma, and several human malignant tumors could be bound to varying amounts of 131I without interfering with the reactivity of these antibodies with their respective tumor cells. Exposure of the mouse tumor cells to radio-iodinated antitumor antibodies in vitro, or the injection of radio-iodinated antitumor antibodies into mice preinoculated with tumor cells resulted in either partial or complete tumor inhibition depending upon the amount of 131I activity carried by the antibodies. Injection of comparable amounts of the immunoglobulin alone or of 131I bound to normal globulin did not cause any tumor inhibition. Intraperitoneally injected radio-iodinated anti-EL4 antibody was found to localize preferentially in the subcutaneous transplants of EL4 lymphoma. Similar localization of intravenously injected radio-iodinated antibodies was observed in the metastases of two cancer patients.

Animals↗
PubMed1975

Suppression of an AKR lymphoma by antibody and chlorambucil.

A cell-surface localizing xenogeneic antibody against an AKR mouse lymphoma of spontaneous origin could be bound to chlorambucil without interference with either the alkylating activity of chlorambucil or the immunologic reactivity of the antibody. Exposure of the lymphoma cells to chlorambucil-bound antibody caused greater tumor inhibition both in vitro and vivo than did the synergistic effect of exposure seperately to the antibody and chlorambucil.

Animals↗
PubMed1975

Endocytosis of chlorambucil-bound anti-tumor globulin following "capping" in EL4 lymphoma cells.

A rabbit 7 S antibody reacting specifically with a tumor assoicated antigen on the surface of mouse EL4 lymphoma cells could form "caps" and subsequently undergo endocytosis even when the antibody was non-covalently bound to chlorambucil. As the alkylation of nuclear DNA appears to be the basis of tumor inhibition by alkylating agents like chlorambucil, facilitation of the transport of chlorambucil across cell membrane by anti-tumor antibodies might explain, at least in part, the increased tumor inhibition by cholorambucil bound anti-tumor antibodies compared to tumor inhibition by equivalent amounts of tumor antibodies or chlorambucil alone.

Animals↗
PubMedDate not supplied

Effects of a high protein diet on the evolution of diabetes in streptozotocin-induced and spontaneously diabetic "BB" Wistar rats.

Recently, we demonstrated a reduction in the diabetogenic action of streptozotocin (STZ) in rats previously adapted to a high protein (HP) diet. These data suggested that amelioration of diabetes resulted from the combination of two effects of the HP diet: initial protection against the diabetogenic action of the drug at the time of exposure and subsequent improvement of the induced diabetic condition. The present study evaluated the effects of a HP diet on the evolution of the metabolic condition in rats with STZ-induced or spontaneous diabetes (BB Wistar rats). Two days after STZ injection, the animals were given isocaloric HP (70% protein, 8% fat) or control (66% carbohydrate, 16% protein, 8% fat) diets for 15 days. After 13 days, the STZ-treated rats fed HP diet showed an impressive decrease in severity of diabetes, as judged by rate of body weight change, plasma glucose, urine volume and glycosuria, serum and pancreatic insulin. The BB Wistar rats, already diabetic for 5 weeks before being transferred to the HP or control diet, were treated with daily injections of insulin. After 31 days on the HP diet, the BB rats showed reduced insulin requirement, reduced blood and urinary glucose levels, but no difference in body weight gain or pancreatic insulin content. The data show that short-term use of HP diets can greatly improve the diabetic condition in STZ-treated animals, but that the beneficial effects of the diet are much less marked in rats with chronic spontaneous diabetes. These data suggest that the ameliorating effect of HP diet is fully manifested only when the diabetic rats have a sufficient number of residual functioning B-cells.

Animals↗