The novel heat-stable enterotoxin subtype gene (ystB) of Yersinia enterocolitica: nucleotide sequence and distribution of the yst genes

The gene (ystB) encoding the novel subtype of the heat-stable enterotoxin (Y-STb) was cloned from the chromosome of a clinical isolate of Yersinia enterocolitica 84-50 (serotype O:5, biotype 1A) and the nucleotide sequence was determined. The ystB contained 216 base pairs that encoded a protein of 71 amino acid residues. The C-terminal 30 residues of the precursor protein exactly corresponded to the amino acid sequence of the Y-STb toxin, purified from the culture supernatant of the wild strain. Homology search revealed that there are 76.9% nucleotide sequence similarity between ystB and the Yersinia kristensenii ST gene, and 73.5% with the Y. enterocolitica prototype sequence of yst (ystA). When tested with the PCR generated ystB specific probe, 36 of 304 Y. enterocolitica strains from 18 countries hybridized with the probe. All the ystB probe positive strains belonged to biotype 1A and mostly to the so-called non-pathogenic serotype O:5, O:6, O:7,8 O:7,13 and O:10, while ystA was predominantly found among the pathogenic serotypes (78.5%). Out of 36 ystB gene positive strains, 18 were clinical origin from six countries, which were also positive in the suckling mice assay suggesting that ystB may play an important role in the pathogenesis, and the so-called non-pathogenic serotypes could be virulent for human.     

Hydrogen sulphide production tests and the detection of groundwater faecal contamination by septic seepage.

The 'H2S test' is being advanced for microbiological water quality testing where conventional coliform based methods are impractical or too expensive. It involves ambient temperature incubation of water samples with nutrient formulated to generate hydrogen sulphide when 'faecal' bacteria are present. Recently a WHO review identified several concerns including the limited number of comparative studies, formulation variability, and false positives and negatives. In response we have compared the H2S test's ability to detect and quantify faecal contamination in an aquifer impacted by septic tank leachfields with measurements obtained concurrently using conventional bacterial indicators, coliphages, faecal sterol biomarkers, Cryptosporidium and Giardia. Like these other analytes, H2S testing detected a contamination gradient ranging from high (septic liquid) to moderate (exfiltration zones), to background (e.g. domestic bores), corresponding to indicator removal + dilution by factors > 10(6). Presence/absence tests could not distinguish between heavily and slightly contaminated waters, whereas multi-tube testing (e.g. 10 x 10 mL arrays) did. It was concluded that while the WHO review concerns are justified, the H2S test performance shows promise in sanitary survey work, can be improved by employing an mpn approach and has potential to aid in the protection of source water and identifying contaminated groundwater.     

Ion chromatography of amylamine and tert.-butylamine in pharmaceuticals

Ion chromatographic (IC) methods have been developed for the assay of amylamine in BMS-181 866-02 and tert.-butylamine (TBA) in BMS-188 494-04. BMS-181 866-02 is the penultimate intermediate in the synthesis of a novel thromboxane antagonist, BMS-180 291-02, which is undergoing clinical trials. Amylamine may be present as a trace impurity in BMS-181 866-02. BMS-188 494-04 is the TBA salt of the prodrug ester of BMS-187 745, a novel oral hypocholesterolemic agent. Chromatographic separations were accomplished under isocratic conditions using a Dionex CS-14 column with conductivity detection. The methods differ only in the composition of the methanesulfonic acid-acetonitrile mobile phase. The detection limit and minimum quantifiable levels for amylamine were 0.01% and 0.02%, respectively. The method was linear over the range studied (1-12.5 micrograms/ml, n = 7, r = 0.9993). The method for TBA was linear from 5 to 30% (w/w) (50-300 micrograms/ml, n = 8, r = 0.9993) of working sample concentration (1 mg/ml BMS-188 494-04). The precision and accuracy of the methods are presented.     

Spectrally selective laminated glazing consisting of solar control and heat mirror coated glass: preparation, characterization and modelling of heat transfer

In this study, solar control coatings were prepared by sequential depositions of thin films of ZnS (40 nm)–CuS (150 nm) and ZnS (40 nm)–Bi₂S₃ (75 nm)–CuS (150 nm) from chemical baths on 3 mm thick commercial sheet glass. These were laminated to 3 mm thick clear glass or commercially available SnO₂ based heat mirror coating of sheet resistance 15 Ω on float glass of 3 mm thickness using a poly(ethylene vinyl acetate), EVA, sheet of 0.36 mm thickness in a vacuum process at 120 °C for 30 min. In total, the thickness of the glazing was 6.35 mm. The glazings possess visible transmittance, weighted for D65 solar spectra and sensitivity of the human eye for daylight vision, of 36% or 14% with solar absorptance of 71% or 78% depending on the coating type, i.e ZnS–CuS or ZnS–Bi₂S₃–CuS-heat mirror respectively. The solar heat gain coefficient (SHGC) was evaluated for these glazings at exterior temperatures of 15 and 32 °C for an exterior convective heat transfer coefficient (h_ex) of 6–100 Wm⁻² K⁻¹ using a mathematical model. The model predicts the extent of reduction in SHGC through the presence of the heat mirror coating as a function of h_ex and hence helps to decide on the relative benefit, which may be derived through their use in different locations. Though the deposition technique mentioned here involves longer duration compared with vacuum techniques, it may be developed into a low throughput, low-capital alternate technology for small-scale production.     

Textural stability as a characterization tool of high temperature catalysts

 Factors, both physical and chemical, influencing the pore-structure stability of high temperature catalysts and/or catalyst supports were discussed with a view to formulate strategies to design and develop high temperature catalyst supports. Factors influencing the sintering behavior and techniques to manipulate them are discussed. Chemical ways of modifying porosity reduction behavior can lead to changes in catalytic behavior. Therefore several physical techniques like control of packing and coordination by post precipitation treatment and nanocomposite formation, changing particle morphology and introducing rigid constraints were discussed. Received: 20 June 1998 / Accepted: 30 July 1998     

Tumour-proliferative fraction and growth factor expression as markers of tumour response to radiotherapy in cancer of the uterine cervix

This study seeks to define the role of pretreatment of evaluation of tumour growth fraction in cervical cancer and its relationship to the clinical course of the disease. In addition, it also seeks to explain whether cell kinetics and growth factor expression have an association with tumour response to radiotherapy and hence could be of value in the management of patients. All pre-treatment biopsies were analysed for the tumour-proliferative compartment by evaluation of Ki67 antigen expression and argyrophilic nucleolar organiser region (AgNOR) counts. Growth factor analysis was done by analysing for expression of epidermal growth factor (EGF), epidermal growth factor receptor (EGF-R) and transforming growth factors alpha and beta (TGFalpha, TGFbeta). A total of 152 patients were evaluated and a correlation obtained between pre-treatment status of the tumour-growth-fraction-associated markers and clinical outcome following radiotherapy. Such patients were either disease-free (group 1, n=106) or with residual/recurrent disease (group 2, n=46) at a 16-month follow-up. Pre-treatment analysis of AgNOR significantly correlated to disease status after treatment (r=-0.517, P=0.0000). This may be due to an effect of cell proliferation. Lower AgNOR counts were significantly associated with recurrent/residual tumours, suggesting that increased proliferative activity may be a positive prognostic indicator. Similar results were also obtained for the other proliferation-associated marker Ki67 (r=-0.443, P=0.0000). Expression of EGF and EGF-R also showed significant pre-treatment correlations with the final disease outcome (r=0.248, P=0.031 and r=0.503, P=0.0000 respectively). Both these markers were expressed more by patients belonging to group 2. The opposite was the case for TGFalpha, where patients belonging to group 1 showed higher values (r=0.417, P=0.0001). The other growth factor investigated, TGFbeta, also showed a conspicuous differential expression in the two groups of patients (r=-0.604, P=0.0000). Group 1 patients showed mostly mild to moderate expression while most group 2 patients were negative for the growth factor. It therefore appears that tumours with high AgNOR counts and Ki67 index, along with expression of the two types of transforming growth factor (alpha and beta), responded better to radiotherapy.     

Synthesis of iron oxide nanoparticles of narrow size distribution on polysaccharide templates

We report here the preparation of nanoparticles of iron oxide in the presence of polysaccharide templates. Interaction between iron (II) sulfate and template has been carried out in aqueous phase, followed by the selective and controlled removal of the template to achieve narrow distribution of particle size. Particles of iron oxide obtained have been characterized for their stability in solvent media, size, size distribution and crystallinity and found that when the negative value of the zeta potential increases, particle size decreases. A narrow particle size distribution with D ₁₀₀ = 275 nm was obtained with chitosan and starch templates. SEM measurements further confirm the particle size measurement. Diffuse reflectance UV-vis spectra values show that the template is completely removed from the final iron oxide particles and powder XRD measurements show that the peaks of the diffractogram are in agreement with the theoretical data of hematite. The salient observations of our study shows that there occurs a direct correlation between zeta potential, polydispersity index, bandgap energy and particle size. The crystallite size of the particles was found to be 30–35 nm. A large negative zeta potential was found to be advantageous for achieving lower particle sizes, owing to the particles remaining discrete without agglomeration.     

Mesenchymal chondrosarcoma of the jaw bones: clinicopathologic study of 19 cases

BACKGROUND: Patients with mesenchymal chondrosarcomas in general have a 5-year survival rate ranging from 42-54.6% and a 10-year survival rate of 28%. Nineteen cases of mesenchymal chondrosarcoma of the jaw bones were reviewed to study their clinicopathologic features and to compare their clinical behavior with that of mesenchymal chondrosarcomas of other locations. METHODS: The patients were 10 males and 9 females (age range, 2-51 years). Sixteen patients were age < 30 years, and the average age at presentation was 19 years. Eleven tumors involved the mandible and eight involved the maxilla. RESULTS: Histologically, the classic picture of a bimorphic tumor, composed of islands of well differentiated hyaline cartilage juxtaposed to a small cell undifferentiated malignancy, was present in every case. Resection, including hemimandibulectomy and hemimaxillectomy, was the main treatment in 16 patients. Seven patients had local recurrence, and five patients developed distant metastases. Six patients died of disease, and the 5-year and 10-year survival rates were 82% and 56%, respectively. CONCLUSIONS: Mesenchymal chondrosarcoma of the jaw bones appears to have a more indolent course than mesenchymal chondrosarcoma of other anatomic     

The enigma of social support and occupational stress: Source congruence and gender role effects.

Research on the potential ameliorating effects of social support on occupational stress produces weak, inconsistent, and even contradictory results. This study of 117 employees, mostly from a southern U.S. hospital supply company, examined potential moderators that were theorized might reduce the confusion: source congruence (congruence between sources of the stressor and of social support) and gender role. Congruence between the sources of stressors and of social support appeared to make little difference in determining the moderating or buffering effect of social support on the relationship between stressors and strain. Gender role, however, may moderate the relationship between social support and individual strains such that more feminine people react more strongly and positively to social support than more masculine people do. (PsycINFO Database Record (c) 2010 APA, all rights reserved)