13C-urea breath test in Helicobacter pylori diagnosis and eradication. Correlation to histology, origin of ''false'' results, and influence of food intake

Obliterative or constrictive bronchiolitis is characterized by narrowing of the small airways, due to submucosal and peribronchiolar fibrosis, with chronic obstruction. The vast majority of cases of bronchiolitis obliterans are associated with other diseases and only few cases are idiopathic. We report on the main computed tomography (CT) methods used study obliterative bronchiolitis, the CT findings and the differential diagnosis with other diseases. The dynamic study of alveolar ventilation with CT uses inspiratory and expiratory CT or high-resolution CT (HRCT), spiral dynamic CT or HRCT with advanced image display, ultrafast CT. In abnormal cases HRCT shows direct and indirect signs of small airways disease. The most common (> 80%) sign of obliterative bronchiolitis is the so-called mosaic oligohemia, with low attenuating lobules, caused by air trapping and best seen on expiratory CT, associated with blood flow redistribution to more normal lobules; this finding simulates the ground-glass pattern from infiltrative lung disease. Differential diagnosis is more difficult in the presence of true ground-glass patterns associated with diffuse bronchiolar obstruction and also with mosaic oligohemia due to pulmonary vascular disease and pulmonary emphysema. HRCT can distinguish these diseases and dynamic CT is more sensitive than functional tests in detecting regional abnormalities and air trapping. The combination of HRCT, rapid volumetric scanning and advanced image display is a powerful tool study the normal and abnormal features of bronchiolar function and alveolar ventilation.     

Mutagenic consequences of the incorporation of 6-thioguanine into DNA

The stimulatory effect of phytin added to skim milk on acid production of Lactobacillus casei was examined. Phytin stimulated acid production of L. casei fairly well. The stimulatory effect of phytin on acid production was not shown when phytin was treated with Dowex 50 (H+) and neutralized by NaOH solution. The incinerated product of phytin maintained almost equal stimulatory effect on acid production as that before processing. The addition of Mn2+ in the amount contained in a reagent phytin augmented the stimulatory effect on acid production markedly. The further addition of Fe3+, Ca2+, Mg2+ and PO4(3-) in amounts corresponding to their contents in the preparation of phytin as well as Mn2+ increased the effect slightly. The four preparations of phytin contained 0.045-0.20% of Mn, and the greater the Mn content was, the greater the potentiation of acid production.     

Production of the 19-kDa antigen of Mycobacterium tuberculosis in Escherichia coli and its purification

The 19-kDa antigen (19Ag) of Mycobacterium tuberculosis (Mt) is a lipoprotein which is released from the organism during growth. In order to study the possible involvement of this antigen in the host protective response against Mt infection, it would be helpful to obtain high-level production of 19Ag from a recombinant organism. We have found that overexpression of the native 19Ag gene in Escherichia coli or yeast leads to products which are aggregated and insoluble. By site-directed mutagenesis of the 19Ag lipoprotein leader sequence, we have generated a mutant gene which directs the production of 19Ag into the periplasmic space of E. coli, from where it can be easily purified in high yield. 19Ag obtained from this mutant construct lacks the lipid-modified N-terminal Cys residue found in the native 19Ag, and is not glycosylated, but is otherwise indistinguishable from 19Ag isolated from Mt culture supernatant.     

Photoelectrocatalytic humic acid degradation kinetics and effect of pH,applied potential and inorganic ions

This study addresses the removal of humic acid (HA) dissolved in an aqueous medium by a photoelectrocatalytic process. UV₂₅₄ removal and the degradation of color (Vis₄₀₀) followed pseudo‐first order kinetics. Rate constants were 1.1 × 10^?1 min^?1, 8.3 × 10^?2 min^?1 and 2.49 × 10^?2 min^?1 (R² > 0.97) for UV₂₅₄ degradation and 1.7 × 10^?1 min^?1, 6.5 × 10^?2 min^?1 and 2.0 × 10^?2 min^?1 for color removal from 5 mg dm^?3, 10 mg dm^?3 and 25 mg dm^?3 HA respectively. Following a 2 h irradiation time, 96% of the color, 98% of the humic acid and 85% of the total organic carbon (TOC) was removed from an initial 25 mg dm^?3 HA solution in the photoanode cell. Photocatalytic removal on the same photoanode was also studied in order to compare the two methods of degradation. Results showed that the photoelectrocatalytic method was much more effective than the photocatalytic method especially at high pH values and with respect to UV₂₅₄ removal. The effect of other important reaction variables, eg pH, external potential and electrolyte concentration, on the photoelectrocatalytic HA degradation was also studied. Copyright © 2003 Society of Chemical Industry     

The impact of multiple failure modes on estimating product field reliability

A difficulty in reliability modeling is how to capture the impact of all of the various reliability defect types. The general approach to optimizing burn-in that we describe in this article addresses a multiple-defect environment. The approach has four main parts: (i) modeling the product's failure rate distribution, (ii) establishing the Pareto distribution of reliability defects, (iii) assessing the kinetic information of each reliability defect, and (iv) estimating the DPPM under product use conditions. This article compares and contrasts the acceleration effects of various extrinsic defects found in 130- and 90-nm CMOS technology products.     

Stressful life events and smoking behaviors in Chinese adolescents: a longitudinal analysis.

The associations between stressful life events and smoking have been established among adolescents in the United States. However, whether these relationships are similar in adolescents from other non-Western cultures is unknown. Understanding these relationships in adolescents may help to provide opportunities to reduce the smoking rates in those cultures by providing positive coping methods that do not include smoking. In this longitudinal study, the associations between nine stressful life events scales and smoking behaviors were examined in a sample of Chinese adolescents. Six of these scales, positive school-related, negative school-related, positive family-related, positive peer-related, negative peer-related, and negative health-related had significantly different means among females and males. Among males, positive school-related stress was a protective factor for smoking susceptibility. Among females, positive school-related stress was a protective factor and negative school-related stress was a risk factor for lifetime smoking, and negative family-related stress was a risk factor for smoking susceptibility. Findings indicate that smoking among male adolescents in China may not be the result of stress; however, in females stress may contribute to the decision to smoke. Future directions are discussed.