Hypercalcaemia in patients with newly diagnosed tuberculosis in Malaysia

A giant hidradenocarcinoma presented by a 75-year-old female is reported. The patient had a malignant transformation within a nodular hidradenoma involving the right postauricular area, which was treated by mass removal and a right radical neck dissection with a free-flap covering. Malignant hidradenocarcinoma is the least common adnexal tumor of uncertain origin. They are usually malignant from their inception, but some develop from a benign counterpart. To the authors' knowledge, only three cases have been reported previously. Two histologically distinct components were seen in this tumor: (i) typical nodular hidradenoma, which constituted a small part of the tumor; and (ii) carcinoma with areas of transition. The secretory cells of hidradenocarcinoma showed decapitation secretion on light and electron microscopic observations, which is evidence of apocrine differentiation. Histologically, this case was concluded as a hidradenocarcinoma arising from a long-standing nodular hidradenoma. A literature review is presented and the histological, immunohistochemical and ultrastructural features are described.     

The reduction of nitrous oxide to dinitrogen by Escherichia coli

Escherichia coli K12 reduces nitrous oxide stoichiometrically to molecular nitrogen with rates of 1.9 mumol/h x mg protein. The activity is induced by anaerobiosis and nitrate. N2-formation from N2O is inhibited by C2H2 (Ki approximately 0.03 mM in the medium) and nitrite (Ki = 0.3 mM) but not by azide. A mutant defective in FNR synthesis is unable to reduce N2O to N2. The reaction in the wild type could routinely be followed by gas chromatography and alternatively by mass spectrometry measuring the formation of 15N2 from 15N2O. The enzyme catalyzing N2O-reduction in E. coli could not be identified; it is probably neither nitrate reductase nor nitrogenase. E. coli does not grow with N2O as sole respiratory electron acceptor. N2O-reduction might not have a physiological role in E. coli, and the enzyme involved might catalyze something else in nature, as it has a low affinity for the substrate N2O (apparent Km approximately 3.0 mM). The capability for N2O-reduction to N2 is not restricted to E. coli but is also demonstrable in Yersinia kristensenii and Buttiauxella agrestis of the Enterobacteriaceae. E. coli is able to produce NO and N2O from nitrite by nitrate reductase, depending on the assay conditions. In such experiments NO2- is not reduced to N2 because of the high demand for N2O of N2O-reduction and the inhibitory effect of NO2- on this reaction.     

Time course of the changes in prednisolone pharmacokinetics after co-administration or discontinuation of rifampin

After intraperitoneal immunization by different sheep erythrocytes doses (1 x 10(6) - 1 x 10(8)) in the spleen of CBA strain and (CBA x C57Bl/6)F1 hybrid mice short-living suppressor cells, which are able to inhibit mature IgM-but not IgG-plaque-forming cells have been revealed. The suppression degree is in direct dependency on the delayed type hypersensitivity effectors activity. The revealed suppressor splenocytes are Thy-1-positive, do not adhere to plastic, are antigen-specific, require the H-2 complex restriction, are unable to homing into regional lymph nodes, their induction is abolished by administration of 200 mg/kg, but not 20 mg/kg of cyclophosphamide. It has been shown that T-suppressors of delayed type hypersensitivity are able to carry out the function of contrasuppressors.     

Expression of lactose permease in contiguous fragments as a probe for membrane-spanning domains

The lactose permease of Escherichia coli is a membrane transport protein containing 12 transmembrane hydrophobic domains connected by hydrophilic loops. Coexpression of lacY gene fragments encoding contiguous polypeptides corresponding to the first and second halves of the permease [Bibi, E., & Kaback, H. R. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 4325-4329] or the first two transmembrane domains and the remainder of the molecule [Wrubel, W., Stochaj, U., Sonnewald, U., Theres, C., & Ehring, R. (1990) J. Bacteriol. 172, 5374-5381] leads to active lactose transport. It is shown here that contiguous permease fragments with discontinuities in loop 1 (periplasmic), loop 6 (cytoplasmic), or loop 7 (periplasmic) exhibit transport activity; however, fragments with discontinuities in transmembrane domains III or VII fail to do so. The results are consistent with the interpretation that contiguous permease fragments with discontinuities in hydrophilic loops form functional duplexes, while fragments with discontinuities in transmembrane alpha-helical domains do not. On the basis of this notion, a series of contiguous, nonoverlapping permease fragments with discontinuities at various positions in loop 6, putative helix VII, and loop 7 were coexpressed to approximate the boundaries of putative transmembrane domain VII. Contiguous fragments with a discontinuity between Leu222 and Trp223 or between Gly254 and Glu255 are functional, but fragments with a discontinuity between Cys234 and Thr235, between Gln241 and Gln242, or between Phe247 and Thr248 are inactive. Therefore, it is likely that Leu222 and Gly254 are located in hydrophilic loops 6 and 7, respectively, while Cys234, Gln241, and Phe247 are probably located within transmembrane domain VII.(ABSTRACT TRUNCATED AT 250 WORDS)