Biomedical subjects
Publications and source records attributed to R E Nelson.
Today, there is an ever increasing need for accessing the intestinal tract for feeding. I have devised a continent gastrostomy. This gastrostomy meets our criteria in that it is relatively easy to construct with a stapler, provides an excellent blood supply and is completely continent and resistant to breakdown. Feeding with gastrostomy is simple: a catheter is inserted at the beginning and removed at the completion of the feeding, yielding no evidence of reflux.
A collagen was isolated from Drosophila E85, Schneider line 2L and Kc cell cultures. The purified protein was characterized and antibodies were raised against it. Immunofluorescence microscopy locates this material to the regions of basement membranes of Drosophila embryos, larvae, and adults. The molecules are mostly, or entirely, homotrimers of one polypeptide chain linked by interchain disulfide bonds. The partial amino acid sequences of a cyanogen bromide cleavage product of this chain are identical with a part of the virtual translation product of the Drosophila pro alpha 1(IV) nucleotide sequence that is reported in the accompanying paper. This gene is at Drosophila chromosome location 25C and was identified by the high homology of one part of it with the noncollagenous carboxyl terminus (NC1) of vertebrate type IV basement membrane collagens (Blumberg, B., MacKrell, A. J., Olson, P. F., Kurkinen, M., Monson, J. M., Natzle, J. E., and Fessler, J. H. (1987) J. Biol. Chem. 262, 5947-5950). In the electron microscope each molecule appears as a thread with a knob at one end, which contains the carboxyl peptide domains. The variation of flexibility of the thread was mapped along its length. Pulse-chase labeling of cell cultures showed that these molecules associate into disulfide-linked dimers and higher oligomers that can be partly separated by velocity sedimentation and are resolved by sodium dodecyl sulfate-agarose gel electrophoresis. Dimers and higher oligomers formed by overlap of the amino ends of molecules were found. Mild pepsin digestion of Drosophila embryos and larvae solubilized the corresponding disulfide-linked collagen molecules, and Staphylococcus aureus V8 protease peptide maps showed the identity of the collagen derived from animals and from cell cultures. Individual, native molecules have a sedimentation coefficient s20,w = 4.1 S, the dichroic spectrum and amino acid composition of a collagen, and a Tm = 31 degrees C. Positive in situ hybridization with a specific probe for this collagen began 6-8 h after egg laying and showed message in the locations of embryos and larvae which reacted with the antibodies. This included some prominent individual cells in the hemolymph.
Thyrotropin (thyroid-stimulating hormone or TSH)-receptor antibodies, important in the pathogenesis of Graves' disease, can be assayed by one of two methods: (1) bioassays that measure stimulation of thyroid cellular activity by patient immunoglobulins or (2) radioreceptor assays that measure inhibition of binding of labeled TSH to TSH receptors by the same substances. In this study, we report our experience with bioassay of thyroid-stimulating immunoglobulins (TSI) based on measurement of generation of cyclic adenosine monophosphate in a clone of the Fisher rat thyroid cell line (FRTL-5) in 279 patients, and we compare, in 163 consecutive samples, the results obtained by a radioreceptor assay for thyrotropin-binding inhibiting immunoglobulins (TBII). Among the untreated, hyperthyroid patients with Graves' disease, TSI were present in 95% (38 of 40), and TBII were present in 85% (17 of 20). In patients with euthyroid Graves' disease, TSI were found in 57% (16 of 28), and TBII were present in 41% (7 of 17). Of 49 nongoitrous and euthyroid controls, only 4% had TSI and 3% had TBII. Extremely high TSI indices were found in all patients who had pretibial dermopathy (N = 10) or severe Graves' ophthalmopathy (N = 19) requiring orbital decompression. We conclude that both assays are highly sensitive and specific in diagnosing Graves' disease. The TSI bioassay was more sensitive (P less than 0.001) than the TBII radioreceptor assay in detection of Graves' disease. In our experience, both assays have proved useful in the diagnosis of euthyroid Graves' disease with ophthalmopathy and atypical manifestations of hyperthyroid Graves' disease.
Transforming growth factor-beta (TGF beta) has been shown to influence the growth and differentiation of many widely varied cell types in vitro, including some that are endocrinologically active. We have investigated the previously unknown effects of this unique growth factor in the differentiated rat thyroid follicular cell line FRTL-5. The cells demonstrated specific, high affinity binding of TGF beta, and as with other epithelial cells, the growth of these thyroid follicular cells was potently inhibited by addition of TGF beta to the culture medium. TGF beta caused a significant reduction in TSH-sensitive adenylate cyclase activity in the cells. The addition of (Bu)2cAMP along with the growth factor to cultures partially reversed the characteristic morphological changes seen with TGF beta, but did not reverse the growth inhibition. To further investigate the possible mechanisms of the effects of TGF beta on the cells, we measured the influence of the growth factor on [125I]TSH binding. TGF beta did not compete for specific TSH-binding sites; however, exposure of the cells to TGF beta for 12 or more h resulted in a dose-dependent down-regulation of TSH receptors that was fully reversible. While cellular proliferation was potently inhibited by TGF beta, differentiated function, as manifest by iodine-trapping ability, was stimulated by the growth factor. This stimulation of iodine uptake was independent of, and additive to, the stimulatory effects of TSH. Finally, FRTL-5 cells in serum-free medium and in response to TSH were shown to secrete TGF beta-like activity that competed for [125I]TGF beta in a RRA. These studies suggest that TGF beta may represent an autocrine mechanism of controlling the growth response to TSH in thyroid follicular cells, while allowing the continuance of differentiated function.
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Neurospora crassa mutants deficient in asparagine synthetase were selected by using the procedure of inositol-less death. Complementation tests among the 100 mutants isolated suggested that their alterations were genetically allelic. Recombination analysis with strain S1007t, an asparagine auxotroph, indicated that the mutations were located near or within the asn gene on linkage group V. In vitro assays with a heterokaryon indicated that the mutation was dominant. Thermal instability of cell extracts from temperature-sensitive strains in an in vitro asparagine synthetase assay determined that the mutations were in the structural gene(s) for asparagine synthetase.
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A mutant of Neurospora crassa with an altered repressible acid phosphatase has been isolated. The enzyme is much more thermolabile than that of wild type, and has an increased Michaelis constant. Tests of allelic interactions (in partial diploids) and in vitro mixing experiments were consistent with the mutation being in the structural gene for the enzyme. This gene, pho-3, was found to be located in the right arm of Linkage Group IV (LGIV). Thus, pho-3 and the structural gene for repressible alkaline phosphatase, pho-2 (LG V), map in separate linkage groups and cannot be part of the same operon. Neither of these structural genes is linked to the known regulatory genes, nuc-1 (LG I), nuc-2 (LG II), and preg (LG II).
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A survey to determine the endoparasitic nematode destroying fungi located within Sand Ridge State Forest of Illinois was conducted from 1 January to 3 April 1973. A total of seven nematode destroying fungal species were isolated from the collected soil samples. Harposporium helicoides, H. crassum, H. lilliputanum are endoparasitic nematophagous fungi that have been isolated previously from the forest soil. Acrostalagmus gonoides, A. obovatus, Cephalosporium balanoides, and Monacrosporium cionopagum are nematophagous fungal species that had not been isolated previously from Illinois soil. Soil pH's and soil nutrient levels were not important in the isolation frequency of the collected endoparasitic nematode destroying fungi.