Colonization of the chicken trachea by an avirulent avian Escherichia coli transformed with plasmid pHK11

Recombinant plasmid pHK11 was transformed into an avirulent, wild-type avian Escherichia coli (E. coli Av) in order to study the plasmid's effect on colonization of the chicken trachea. The transformant (E. coli Av + pHK11) produced colicin V (ColV), had type F1 fimbriae, and was motile. The E. coli Av recipient possessed type F1 fimbriae but was nonmotile; it did not produce ColV. Four-day-old chicks were inoculated in the trachea with 100 microliters of an overnight culture (approximately 10(8) colony-forming units) of E. coli Av, E. coli Av + pHK11, or sterile brain-heart infusion (BHI) broth. A group of uninoculated chicks was also included. Samples of the trachea were taken on days 4 and 10 postinoculation and compared histologically and bacteriologically. Birds inoculated with E. coli Av + pHK11 had enhanced tracheal colonization and showed increased histologic changes as compared with those inoculated with E. coli Av or BHI broth or uninoculated controls. These results indicate that production of ColV and motility enhance the colonization of the trachea and may be involved in the cause of pathologic lesions.     

Comparative pulmonary absorption, distribution, and toxicity of copper gallium diselenide, copper indium diselenide, and cadmium telluride in Sprague-Dawley rats

Copper gallium diselenide (CGS), copper indium diselenide (CIS), and cadmium telluride (CdTe) are novel compounds used in the photovoltaic and semiconductor industries. This study was conducted to characterize the relative toxicities of these compounds and to evaluate the pulmonary absorption and distribution after intratracheal instillation. Female Sprague-Dawley rats were administered a single equimolar dose (70 mM) of CGS (21 mg/kg), CIS (24 mg/kg), CdTe (17 mg/kg), or saline by intratracheal instillation. Bronchoalveolar lavage fluid (BALF) protein, fibronectin, inflammatory cells, lung hydroxyproline, and tissue distribution were measured 1, 3, 7, 14, and 28 days after instillation. Relative lung weights were significantly increased in CIS- and CdTe-treated rats at most time points. Inflammatory lesions in the lungs consisting of an influx of macrophages, lymphocytes, and PMNs were most severe in CdTe-treated rats, intermediate in CIS-treated rats, and minimal in rats receiving CGS. Hyperplasia of alveolar type 2 cells was present in CIS- and CdTe-treated rats and was greatest in CdTe-treated rats. Pulmonary interstitial fibrosis was observed in CdTe-treated rats at all time points. All three compounds caused marked increases in total BALF cell numbers, with the greatest increase observed in CIS-treated rats. BALF protein, fibronectin, and lung hydroxyproline were significantly increased in all treated animals and were highest in CdTe-treated animals. There was no apparent pulmonary absorption or tissue distribution of CGS. Indium levels increased in extrapulmonary tissues of CIS-treated rats, although Cu and Se levels remained unchanged. CdTe was absorbed from the lung to a greater extent than CGS and CIS. Cd and Te levels decreased in the lung and increased in extrapulmonary tissues. Of these compounds CdTe presents the greatest potential health risk because it causes severe pulmonary inflammation and fibrosis and because it is readily absorbed from the lung may potentially cause extrapulmonary toxicity.     

Ligand-induced conformational change in penicillin acylase

Wild-type and constitutively active mutants of human MAP kinase kinase-1 (MKK1) were analyzed by deuterium exchange mass spectrometry using a protocol that minimized loss of deuterium during analysis due to back exchange. The observed peptides accounted for 335 out of 393 residues. Not counting overlap peptides, three peptides showed decreased exchange in constitutively active compared to wild-type MKK1 and nine showed increased exchange. Backbone amides in which exchange rates decreased upon kinase activation were observed near the regulatory phosphorylation sites Ser218 and Ser222 and the adjacent beta9 strand. These decreases are consistent with electrostriction or reduced solvent access due to domain closure or formation of new hydrogen or salt bonds around the catalytic cleft and within the activation lip. Increased exchange upon activation was observed within six peptides derived from helix C and the five-stranded beta sheet from the N-proximal lobe of the conserved kinase domain and in one peptide located at the interface between the N- and C-proximal lobes. Two amides that underwent increased exchange were specifically localized between residues 68 and 69 in beta1 and 140 and 142 in beta5. These residues probably form contacts with each other on opposite sites of the beta sheet as well as with helix C. These increases appeared to represent localized fluctuations, rather than rigid body rearrangements, suggesting that MKK1 activation requires enhanced flexibility within the N-proximal lobe, perhaps to accommodate ATP binding, phosphotransfer, or ADP release.     

Complications of latissimus dorsi myocutaneous flap breast reconstruction

Two qualitative rapid appraisal techniques were used in a community-based study to investigate health beliefs, attitudes and practices in a rural district in Nepal. Pregnancy and childbirth remain non-medical activities managed at home. Deaths may be avoided by better access to hospital emergency services. Health awareness of some problems, e.g. oral rehydration and diarrhoeal disease, is high; but of others, e.g. association of haemoptysis with tuberculosis, is poor. These methods require few resources, are efficient in time and manpower required, and generate useful relevant information on a target population. They are recommended for district health development programmes elsewhere.     

Predicting the time course of haemoglobin in children treated with erythropoietin for renal anaemia

AIMS: To establish a pharmacodynamic model that allows one to predict the haemoglobin (Hb) response to EPO in children as a function of dose and time, and to derive recommendations for initial dosing and subsequent dose adjustment. METHODS: Haemoglobin was monitored in eight children aged 8-15 years with anaemia due to renal failure during treatment with EPO. All patients were free of conditions known to impair the response to EPO. Pretreatment Hb was 4.9-9.0 g dl(-1). The drug was administered once weekly by subcutaneous injection; doses ranged from 1700 to 6800 U week (-1). Hb was monitored for 4-38 months. The Hb-time data were analysed by applying a population pharmacodynamic model proposed for EPO in adult haemodialysis patients. Internal model validation was carried out by using a bootstrap procedure. RESULTS: The increase of Hb during treatment with EPO was linear until steady state was reached after 103+/-33 days (mean +/- interindividual s.d.). The weekly gain in Hb from the onset of therapy to steady state was 0.0805+/-0.026 g dl(-1) (mean +/- interindividual s.d.) for every 1000 U EPO week (-1); it did not exhibit a dependence on body weight. Estimated mean prediction errors are +/-1.53 g dl(-1) for predictions that are based on the mean population parameters and +/-0.83 g dl(-1) for predictions that take into account the complete individual Hb-time data up to and including steady state. CONCLUSIONS: The model describes the time course of the Hb response to EPO in children with renal anaemia. The required weekly EPO dose should initially be calculated from the individual pretreatment Hb and the desired Hb at steady state by using the mean population estimates of the weekly gain in Hb per dose unit before steady state (beta) and the time needed to reach steady state (tau). A reduction of the initial dose according to body weight is not justified by the available evidence. beta should be re-estimated individually after 6 weeks of treatment and dose should be adjusted accordingly. A final dose adjustment should be made when steady state has been reached based on individual estimates of beta and tau.