Interaction of lipopolysaccharides of Helicobacter pylori with basement membrane protein laminin.

The ability of hemagglutinating and poorly hemagglutinating strains of the gastroduodenal pathogen Helicobacter pylori to bind 125I-radiolabelled laminin was quantitated in a liquid phase assay. Although all strains bound laminin, some hemagglutinating strains were good binders of laminin (maximum of 31% binding), whereas poorly hemagglutinating strains bound intermediate to small amounts of laminin (minimum of 6% binding). Since a hydrophobic component of the bacterium has been reported to be involved in binding of laminin (T. J. Trust, P. Doig, L. Emödy, Z. Kienle, T. Wadström, and P. O'Toole, Infect. Immun. 59:4398-4404, 1991), we investigated the role of lipopolysaccharide (LPS) in the interaction of both types of strains with laminin. Although the extent of inhibition varied among strains, laminin binding to hemagglutinating and poorly hemagglutinating strains was inhibited with homologous and heterologous smooth-form LPS. The ability of heterologous rough-form LPS to produce inhibition comparable to that shown by smooth-form LPS indicated that the O side chain of H. pylori LPS was not involved in the interaction. Further inhibition experiments with dephosphorylated LPS, isolated core oligosaccharide, and free lipid A suggested that a phosphorylated structure in the core oligosaccharide mediates the interaction of a hemagglutinating strain of H. pylori with laminin, whereas a conserved nonphosphorylated structure in the core oligosaccharide mediates the interaction of a poorly hemagglutinating strain. Furthermore, we showed that the interaction of H. pylori LPS with 125I-radiolabelled laminin in a solid phase assay was saturable, specific, and inhibitable with unlabelled laminin. It was postulated that the initial recognition and binding of laminin by H. pylori may occur through LPS and that subsequently a more specific interaction with a lectin-like adhesin on the bacterial surface occurs.     

Occupational class and ischemic heart disease mortality in the United States and 11 European countries.

OBJECTIVES: Twelve countries were compared with respect to occupational class differences in ischemic heart disease mortality in order to identify factors that are associated with smaller or larger mortality differences. METHODS: Data on mortality by occupational class among men aged 30 to 64 years were obtained from national longitudinal or cross-sectional studies for the 1980s. A common occupational class scheme was applied to most countries. Potential effects of the main data problems were evaluated quantitatively. RESULTS: A north-south contrast existed within Europe. In England and Wales, Ireland, and Nordic countries, manual classes had higher mortality rates than nonmanual classes. In France, Switzerland, and Mediterranean countries, manual classes had mortality rates as low as, or lower than, those among nonmanual classes. Compared with Northern Europe, mortality differences in the United States were smaller (among men aged 30-44 years) or about as large (among men aged 45-64 years). CONCLUSIONS: The results underline the highly variable nature of socioeconomic inequalities in ischemic heart disease mortality. These inequalities appear to be highly sensitive to social gradients in behavioral risk factors. These risk factor gradients are determined by cultural as well as socioeconomic developments.     

Socioeconomic inequalities in mortality among women and among men: an international study

OBJECTIVES: This study compared differences in total and cause-specific mortality by educational level among women with those among men in 7 countries: the United States, Finland, Norway, Italy, the Czech Republic, Hungary, and Estonia. METHODS: National data were obtained for the period ca. 1980 to ca. 1990. Age-adjusted rate ratios comparing a broad lower-educational group with a broad upper-educational group were calculated with Poisson regression analysis. RESULTS: Total mortality rate ratios among women ranged from 1.09 in the Czech Republic to 1.31 in the United States and Estonia. Higher mortality rates among lower-educated women were found for most causes of death, but not for neoplasms. Relative inequalities in total mortality tended to be smaller among women than among men. In the United States and Western Europe, but not in Central and Eastern Europe, this sex difference was largely due to differences between women and men in cause-of-death pattern. For specific causes of death, inequalities are usually larger among men. CONCLUSIONS: Further study of the interaction between socioeconomic factors, sex, and mortality may provide important clues to the explanation of inequalities in health.     

Bias related to the exclusion of the economically inactive in studies on social class differences in mortality

BACKGROUND: To assess how the exclusion of the economically inactive affects levels and trends in social class differences in mortality among men and women at different durations of follow-up. METHODS: Records of the 1970, 1975, 1980 and 1985 censuses on Finnish men and women aged 35-64 linked with records of all deaths during 1971-1990. RESULTS: Exclusion of the economically inactive population underestimates the class differences in the total population by about 25% among men and 60% among women. The bias does not disappear if the first 5 years of follow-up are excluded and the bias can lead to erroneous conclusions about the trends in social class differences in mortality. CONCLUSIONS: Analyses based on the economically active population may lead to significant underestimation of social class differences in mortality, introduce biases in international comparison and may only partially capture the causal mechanisms underlying these mortality differences. Our results further show that although the bias diminishes during the follow-up, it is by no means eliminated after the first 5 years. The underestimation of social class differences in mortality created by the exclusion of the inactive should be more widely recognized and more accurate data on previous occupations should be collected.     

Effect of occupational mercury exposure on plasma lysosomal hydrolases

Summary The activities of three plasma lysosomal hydrolases, -galactosidase, -glucuronidase and -N-acetylglucosaminidase, were studied in 20 workers exposed to metallic mercury vapor in a chlorine alkali plant and in 10 nonexposed referents. The urinary excretion and blood levels of mercury were determined on the day of study, and the history of mercury exposure was reviewed from the records of mercury concentrations in urine and blood over periods of up to 133 months. The average levels of -N-acetylglucosaminidase and -glucuronidase were higher in the plasma of exposed workers, but the difference was not significant. No significant positive correlation was seen between lyosomal enzyme activities and cumulative long-term exposure to mercury. It is concluded that measurement of plasma lysosomal hydrolase-activities is not of great value in the biological monitoring of workers exposed to low concentrations of metallic mercury vapor.In line with published data, the concentration of mercury showed a clearcut diurnal variation in nonexposed persons, persons currently exposed and persons with a history of past exposure. The excretion rate of mercury remained constant throughout the day.     

Molecular diversity of tobacco vein banding mosaic virus

Summary Tobacco vein banding mosaic virus (TVBMV) is of increasing importance in tobacco production on the Chinese mainland. The 3′-terminal genomic sequences (1624 nucleotides) of 12 TVBMV isolates from China were determined and compared to the sequences of only four TVBMV isolates available in databanks. The results revealed that TVBMV consists of several phylogenetically distinguishable strains that show a degree of correlation with the geographical origin. Two isolates from Yunnan had a unique putative NIb/CP proteolytic cleavage site of Q/N that is uncommon for potyviruses, whereas other TVBMV isolates had the more typical Q/G amino acids at that site. One isolate (ZB6) from Zibo, Shandong Province, was predicted to have experienced recombination within the characterized genomic region. First two authors contributed equally.     

Diminishing educational differences in breast cancer mortality among Finnish women: a register-based 25-year follow-up

OBJECTIVES: This study examined trends in breast cancer mortality by education, age, and birth cohort. METHODS: Census records of Finnish women 35 years and older were linked with death records for 1971 through 1995. RESULTS: Excess breast cancer mortality of more-educated women has declined rapidly, mainly because of increasing mortality among less-educated women and stable or decreasing mortality among more-educated 35- to 64-year-old women. During the 1990s, mortality among more-educated 50- to 64-year-old women declined particularly fast. CONCLUSIONS: The causes of declining differences by education in breast cancer mortality are difficult to verify, but they may be due in part to narrowing differences in reproductive behavior among the younger birth cohorts and to a period effect possibly associated with the introduction of breast cancer screening in the late 1980s.     

Trends in socioeconomic disparities in stroke mortality in six european countries between 1981-1985 and 1991-1995

This study assesses whether stroke mortality trends have been less favorable among lower than among higher socioeconomic groups. Longitudinal data on mortality by socioeconomic status were obtained for Finland, Norway, Denmark, Sweden, England/Wales, and Turin, Italy. Data covered the entire population or a representative sample. Stroke mortality rates were calculated for the period 1981-1995. Changes in stroke mortality rate ratios were analyzed using Poisson regression and compared with rate ratios in ischemic heat disease mortality. Trends in stroke mortality were generally as favorable among lower as among higher socioeconomic groups, such that socioeconomic disparities in stroke mortality persisted and remained of a similar magnitude in the 1990s as in the 1980s. In Norway, however, occupational disparities in stroke mortality significantly widened, and a nonsignificant increase was observed in some countries. In contrast, disparities in ischemic heart disease mortality widened throughout this period in most populations. Improvements in hypertension prevalence and treatment may have contributed to similar stroke mortality declines in all socioeconomic groups in most countries. Socioeconomic disparities in stroke mortality generally persisted and may have widened in some populations, which fact underlines the need to improve preventive and secondary care for stroke among the lower socioeconomic groups.