Graves' ophthalmopathy

Ophthalmopathy develops in about 30% of patients who have Graves' disease. The pathogenesis, like that of the hyperthyroidism, is probably autoimmune in nature. The eye manifestations are diverse and include lid lag, soft tissue swelling, proptosis, corneal damage, diplopia, and optic neuropathy. The natural history is benign in 90% of patients, with gradual improvement over time. Therapeutic options include corticosteroid therapy, radiation, and surgical treatment. The last is usually the therapy of choice for severe or disfiguring ophthalmopathy.     

Detection of monosomy 7 and trisomy 8 in myeloid neoplasia: a comparison of banding and fluorescence in situ hybridization

Fluorescence in situ hybridization (FISH) is a powerful tool for detection of numerical and structural chromosomal aberrations. We have compared conventional banding techniques and FISH for the detection of monosomy 7 (-7) and trisomy 8 (+8) in 89 patients with myeloid malignancies. Of these patients, 21 had -7, 30 had +8, four had both, and 34 had no aberrations or aberrations other than -7 or +8 as assessed by banding techniques. Sequential samples were available in 23 patients. Alphoid DNA probes specific for chromosomes no. 7 and 8 were used for FISH. As controls, 10 normal bone marrow (BM) samples were hybridized with the chromosomes no. 7 and 8 probes, and in addition all tumor samples were hybridized with a chromosome no. 1 specific probe. The cut-off value for -7 was 18% one-spot cells, and for +8 was 3% three-spot cells. FISH analysis of 44 samples with -7 or +8, and at least 10 metaphases evaluated, showed that the proportions of aberrant metaphase cells mirrored the interphase clone sizes. Most samples with nonclonal metaphase aberrations, including those with only a few metaphases, had increased numbers of aberrant interphase cells: 20% to 80% for -7, and 3% to 43% for +8. Interphase cytogenetics of the 34 samples without -7 or +8 did not show significant cell populations with -7 or +8. In four patients, -7 or +8 could not be confirmed by FISH due to additional structural aberrations, marker chromosomes, or wrongly interpreted banding results. As FISH will be used more and more in cytogenetic diagnosis, clinical follow-up, and therapy monitoring, it will be necessary to standardize FISH procedures and supplement the Standing Committee on Human Cytogenetic Nomenclature (ISCN) definitions of a clone with criteria specifically for in situ hybridization.     

Regulation of the mature human T cell receptor gamma repertoire by biased V-J gene rearrangement

Vacuolar apical compartment (VAC) is a transient organelle originally observed in Madin-Darby canine kidney (MDCK) epithelial cells impaired from forming cell-cell contacts. VACs are large vacuoles which contain microvilli and apical plasma membrane markers (among others, a 184-kDa plasma membrane protein, AP2), but exclude basolateral membrane markers. Upon reestablishment of cell-cell contacts, VACs are rapidly (within 1 h) exocytosed toward intercellular spaces, after which the apical plasma membrane drifts toward its final destination (Vega-Salas, Salas, and Rodriguez-Boulan. 1988. J. Cell Biol. 107, 1717-1728). In this work, we studied the role of cAMP as a mediator for the exocytosis of VACs. We shifted confluent cells from low to normal calcium medium (thus reestablishing cell-cell contacts and causing VAC exocytosis), a shift which resulted in a significant rise of cellular levels of both total intracellular and protein-bound cAMP. The 8-Br analog of cAMP (8-Br-cAMP) (5-50 microM) caused externalization of the intracellular compartment of AP2 as measured by radioimmunoassay. A similar effect was observed with 3-isobutyl-1-methylxanthine. 8-Br-cAMP also caused the appearance of AP2-positive VAC images in nonpermeabilized cells, namely, VACs that become accessible to extracellular antibodies upon fusion with the plasma membrane. Lanthanum, which abolishes the peak of intracellular free calcium during a calcium switch, failed to block the exocytosis. On the other hand, 12-O-tetradecanoylphorbol-13-acetate induced only a modest exocytic response. Finally, 8-Br-cAMP induced VAC exocytosis in sparse MDCK cells grown in normal calcium medium. These data indicate that cAMP is a mediator between the extracellular signal provided by cell-cell contacts and VAC exocytosis.     

"Woolly everlasting daisy" (Helichrysum blandoskianum) toxicity in cattle and sheep

Investigations into cattle mortalities suspected of being caused by the Woolly Everlasting Daisy (Helichrysum blandowskianum) revealed lesions of marked periacinar liver necrosis, vascular degeneration, widespread haemorrhages and oedema. Brains showed status spongiosus. These lesions were reproduced in cattle and sheep fed Helichrysum and in cattle given an intravenous injection of an extract of the plant.     

Effect of testosterone on long-term organ cultures of canine prostate

Organ cultures of rodent and human prostate glands have shown marked differences in their morphological response to testosterone. In this study, explants from 19 canine prostate glands were cultivated for a minimum of 9 days in Trowell's T-8 medium. Groups of explants were exposed to media containing from 0.05 to 100 mum testosterone. While the higher testosterone levels (50 and 100 mum) markedly decreased explant viability, explants cultivated at lower levels (0.05 to 5 mum) appeared similar to control explants in testosterone-free Trowell's T-8 medium. Atmospheric mixtures containing either 95% or 50% oxygen were equally effective. Shortly after the cultures were initiated, large amounts of secretory product were liberated into the lumen. After 9 or more days in vitro, glandular epithelium appeared cuboidal and never revealed the acid phosphatase-rich secretory granules seen in the preculture control. However, the epithelium exhibited an increase in alkaline phosphatase and lipid content following cultivation.     

Evidence for multiple substrate-reduction sites and distinct inhibitor-binding sites from an altered Azotobacter vinelandii nitrogenase MoFe protein

The arginine-277 residue of the alpha-subunit of the nitrogenase MoFe protein was targeted for substitution because it is (i) a close neighbor of alpha-cysteine-275, which is one of only two residues anchoring the FeMo cofactor to the polypeptide, and (ii) a component of a potential channel for entry/exit of substrates/products and for accepting FeMo cofactor during MoFe-protein maturation. Several of the eight mutant strains constructed were capable of good diazotrophic growth and also contained FeMo cofactor as indicated by its biologically unique S = 3/2 EPR spectrum. These observations indicate that the positively charged alpha-arginine-277 residue is not required for acceptance of the negatively charged FeMo cofactor by the separately synthesized, cofactor-deficient, apo-MoFe protein. The wide range of nitrogen-fixation phenotypes shown by these mutant strains generally correlated well with their C2H2- and proton-reduction activities, which range from 5 to 65% of wild-type activity. One notable exception is the histidine-substituted strain, DJ788 (alpha-277His). This strain, although unable to fix N2 and grow diazotrophically, elaborates an altered alpha-277His MoFe protein that catalyzes the reduction of the alternative substrates, C2H2, HCN, HN3, and protons. These observations are best explained if multiple redox levels are available to the MoFe protein but the alpha-277His MoFe protein is incapable of reaching the more-reduced redox levels required for nitrogen fixation. Under nonsaturating CO concentrations, the alpha-277His MoFe-protein-catalyzed reduction of C2H2 showed sigmoidal kinetics, which is consistent with inhibitor-induced cooperativity among two C2H4-evolving sites and indicates the presence of three sites, which can be simultaneously occupied, on the MoFe protein. Similar kinetics were not observed for alpha-277His MoFe-protein-catalyzed reduction of either HCN or HN3 with nonsaturating CO levels, indicating that these substrates are unlikely to share common binding sites with C2H2. Further, CN- did not induce cooperativity in C2H2 reduction and, therefore, CO and CN- are unlikely to share a common binding site. These changed substrate specificities, reinforced by changes in the FeMo-cofactor-derived S = 3/2 EPR spectrum, clearly indicate the importance of the alpha-277 residue in catalysis and the delicate control exerted on the properties of bound FeMo cofactor by its polypeptide environment.