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Biomedical subjects

A D Bloom

Publications and source records attributed to A D Bloom.

At least 37 records · Page 2Linked to original sources
PubMed1986

Indefinite survival of rat parathyroid allografts without postoperative immunosuppression.

Methods that avoid long-term immunosuppression must be developed for human parathyroid allotransplantation to be feasible. Pretransplant treatment of the graft to eliminate passenger cells is one such method. An alternative approach is short-term treatment of the recipients with cyclosporine (CsA). In this study, parathyroid glands from Lewis X Brown Norway rats were cultured for 1 week and treated with antiserum directed against class II major histocompatibility complex antigens. Treated glands were transplanted into hypocalcemic Wistar-Furth recipients that previously received 30 mg/kg of CsA once a day for 3 days before transplantation. At 280 days after transplantation, 67% of the recipients had functional parathyroid allografts. Control rats (no CsA; fresh, untreated glands) rejected these grafts within 28 days. Control rats given 3 days of CsA and transplanted with fresh, untreated glands had functional grafts for greater than 56 days (median survival, 80.5 days). Prolongation of allograft survival with short-term, preoperative CsA demonstrates the efficacy of immunosuppression given at the time of antigen presentation. This course of CsA is even more effective when the recipient receives a graft whose passenger cells are eliminated.

Animals↗
PubMed1985

Development of a standard protocol for in vitro cytogenetic testing with Chinese hamster ovary cells: comparison of results for 22 compounds in two laboratories.

A major problem of cytogenetics testing in mammalian cells is lack of agreement of results among laboratories. Our objective was to develop a sensitive in vitro test protocol that was applicable to large-scale chemical screening and yielded comparable results in two laboratories. We used sister chromatid exchange (SCE) and chromosome aberration (CAb) tests in Chinese hamster ovary (CHO) cells. The initial protocol used standard cell densities, medium, batch of rat liver S9 for metabolic activation; positive, negative, and solvent controls; staining and scoring techniques; and fixation times. Treatment without S9 was for 8-12 hr (CAb) or 26 hr (SCE), and with S9 for 2 hr in serum-free medium. Bromodeoxyuridine (BrdUrd) (10 microM) was added to SCE cultures only, 2 hr after addition of the test chemical. Doses were based on the 50% toxicity level in a preliminary test of cell survival 24 hr after treatment. One hundred cells (CAb) or 50 cells (SCE) were scored from each control and from five dose levels. Five clastogens were tested in the first two-laboratory comparison: mitomycin-C, triethylenemelamine, N-methyl-N'-nitro-N-nitrosoguanidine, cyclophosphamide, and benzo(alpha)pyrene. There was quite good agreement between laboratories. Seventeen compounds were then tested "blind" in the two laboratories. As testing proceeded, some discrepancies occurred between the laboratories, and the protocol was modified in attempts to improve the resolution of marginal responses and make dose selection more consistent. The preliminary test for cell survival was omitted. A 10(5) dose range in a half-log series was tested, and cells were scored at the highest dose at which sufficient mitotic cells were obtained, and at the next two lower doses. By delaying fixation times, SCE and CAb were scored at doses that inhibited cell cycle progression. This protocol gave comparable results in the two laboratories in many cases and by testing up to a maximum dose, limited by solubility and/or toxicity, should detect a high proportion of clastogens and SCE inducers.

Animals↗
PubMed1980

Baller-Gerold syndrome craniosynostosis-radial aplasia syndrome.

A new case of the Baller-Gerold syndrome is described in a 6 1/2-year-old, black male who presented at birth with bilateral synostoses of the coronal and lambdoidal sutures, bilateral radial aplasia, vertebral anomalies and genito-urinary malformations. The parents and siblings were unaffected, and there was no history of consanguinity. A review of the history and physical findings in our patient and in the four other patients previously reported in the literature is provided, with a discussion on pathogenesis, prognosis and the possible autosomal recessive mode of inheritance of the syndrome.

Abnormalities, Multiple↗
PubMed1979

Preliminary communication: prenatal detection of the Fanconi Anemia gene by cytogenetic methods.

We have studied the pattern of chromosome instability in cultured fibroblasts and fetal membrane cells from a fetus aborted by an individual with a history of a previous child affected with Fanconi anemia (FA). These cells exhibited a low level of spontaneous chromosome instability. Upon treatment with diepoxybutane (DEB), chromosome breakage increased to a level comparable to that reported earlier in DEB-treated FA heterozygous cells. Cultured cells derived from chromosomally normal fetuses which served as controls did not show DEB-induced chromosome breakage. This observation suggests that the fetus studied is heterozygous for the FA gene. The ability to distinguish readily between the three genotypes (homozygous FA, heterozygous FA, and normal) in an in vitro stress system that measures the response of the cells to a clastogenic agent makes available a test for the prenatal and postnatal detection of the FA gene.

Adult↗
PubMed1977

Argininosuccinate synthetase activity in cultured human lymphocytes.

The activity of argininosuccinate synthetase (E.C. 6.3.4.5), a urea cycle enzyme, was measured in cultured human lymphocytes using a new radioactive assay. Control cells had a maximum specific activity of 15.7 +/- 8.7 nmoles per hour per milligram of protein and an apparent Km for citrulline of 2 X 10(-4) M, whereas cells derived from a patient with citrullinemia had no detectable activity. A nutritional variant, selected out of the citrullinemic lymphocyte population by ability to grow in citrulline, had a maximum specific activity of 10.7 +/- 3.8 nmoles/hr/mg and an apparent Km for citrulline of 2 X 10(-2) M. These measurements confirm the observation that citrullinemia is associated with a defect in argininosuccinate synthetase activity and provide further evidence that citrullinemia is expressed in cultured lymphocytes. The emergence of a nutritional variant with a partial defect in argininosuccinate synthetase enzyme suggests that this citrullinemic patient has a heterogeneous population of cells, some totally defective and others only partially defective in argininosuccinate synthetase. The new activity assay is described in detail.

Amino Acid Metabolism, Inborn Errors↗
PubMed1975

Citrulline metabolism in normal and citrullinemic human lymphocyte lines.

Citrullinemia is one of the five aminoacidurias associated with the Krebs-Henseleit urea cycle. A long-term lymphocyte line (UM-21) derived from a patient with this disease and nine of ten clones of this line were found to have no activity for the enzyme argininosuccinate synthetase (AS), as demonstrated by their inability to grow in medium in which citrulline had been substituted for arginine, by their inability to incorporate arginine-C14 derived from citrulline-C14 into cellular protein, and by direct enzyme assay. One clone had normal or nearly normal argininosuccinate synthetase activity, as demonstrated by the same criteria. Nutritional "variants" able to grow logarithmically in medium containing citrulline were isolated from UM-21 and three clones. The apparent Kms of AS for citrulline in UM-21, the ten clones, the variant lines, and a normal line were measured and fell into three groups: AS in UM-21 and nine clones had no measurable apparent Km for citrulline; AS in the variant cells had apparent Kms for citrulline of approximately 20 mM; and AS in the normal cell line and one clone had apparent Kms for citrulline of 0.2 mM. The data suggest that the defect in the citrullinemic cell lines is due to a mutation in the structural gene coding for argininosuccinate synthetase.

Amino Acid Metabolism, Inborn Errors↗
PubMed1974

Establishment of a tetraploid, immunoglobulin-producing cell line from the hybridization of two human lymphocyte lines.

We here report the establishment of a seemingly permanent hybrid cell line formed by fusion of the cells of two biochemically mutant human lymphocyte lines. One parental line (UM-1-6TGr) was deficient in hypoxanthine-guanine phosphoribosyl transferase (IMP: pyrophosphate phosphoribosyltransferase, EC 2.4.2.8), and had two marker chromosomes. The second parental line (UM-21-5) was a clonal derivative of a citrullinemic lymphocyte line, and was, like the line of origin, dificient in argininosuccinic acid synthetase [(L)-Citrulline: (L)-aspartate ligase (AMP-forming), EC 6.3.4.5]. This line also had a marker chromosome, which was a B5 with a very prominent secondary constriction. After trypsinization of both parental lines, followed by addition to the fusion mixture of beta-propiolactone-inactivated Sendai virus, the cells were placed in a doubly selective medium (hypoxanthine-aminopterin-thymidine-containing medium in which the arginine was replaced with citrulline) to prevent the proliferation of the mutant parents. Under selective conditions, 97-99% of cells were found to be tetraploid, containing the three marker chromosomes; and the specific activities of the hybrid line transferase and synthetase were intermediate between normal and mutant line values. Furthermore, the UM-1-6TGr and UM-21-5 lines were producers of gamma and mu heavy chains of immunoglobulin, and of kappa light chains, as determined by immunodiffusion and immunofluorescence, and the hybrid line continued to synthesize and to secrete detectable levels of these same immunoglobulins. These studies demonstrate the genic and cytogenetic stability of this hybridized lymphocyte cell line, and prove that hybridization per se does not extinguish the activity of either the regulatory of structural genes involved in immunoglobulin synthesis.

Cell Fusion↗