Adhesion of viridans group streptococci to sialic acid‐, galactose‐ and N‐acetylgalactosamine‐containing receptors

The binding of 10 viridans group streptococci to sialic acid‐, galactose (Gal)‐ and N‐acetylgalactosamine (GalNAc)‐containing receptors was defined by analysis of the interactions between these bacteria and structurally defined glycoconjugates, host cells and other streptococci. All interactions with sialic acid‐containing receptors were Ca²⁺‐independent as they were not affected by ethyleneglycoltetraacetic acid (EGTA), whereas all interactions with Gal‐ and GalNAc‐containing receptors were Ca²⁺‐dependent. Recognition of sialic acid‐, Gal‐ and GalNAc‐containing receptors varied widely among the strains examined, in a manner consistent with the association of each of the three lectin‐like activities with a different bacterial cell surface component.     

Joint effects of body weight and alcohol on elevated serum alanine aminotransferase in the United States population.

BACKGROUND & AIMS: Both alcohol and obesity are associated with hepatic steatosis. However, little is known about whether the toxicity of alcohol to the liver is influenced by adiposity. We examined the relationship of alcohol drinking and binge drinking with abnormal serum aminotransferase activity in normal weight, overweight, and obese persons in a national, population-based study. METHODS: Data were analyzed from 13,580 adult participants in the third US National Health and Nutrition Examination Survey, 1988-1994, after excluding participants with hepatitis B or C or iron overload. Abnormal aminotransferase levels were defined by using sex-specific cutoffs for ALT and AST. Analyses were adjusted for other liver injury risk factors. RESULTS: The prevalence of abnormal aminotransferase activity was elevated with consumption of >2 drinks per day or with overweight and obesity. In multivariate analysis, there was no association of alcohol intake with a higher prevalence of elevated aminotransferase levels among normal weight persons. In contrast, among overweight persons, consumption of >2 drinks per day increased the risk of elevated aminotransferase levels, and among the obese, > or = 1 drink per day was associated with a higher risk. Results were similar with elevated ALT alone as the outcome. With elevated AST alone as the outcome, intake of >2 drinks per day increased the risk, even among normal weight persons. Binge drinking was associated with aminotransferase elevation among obese consumers of 1-2 drinks per day. CONCLUSIONS: In this large, national, population-based study, overweight and obesity increased the risk of alcohol-related abnormal aminotransferase activity.     

Salivary protein adsorption and Streptococccus gordonii adhesion to dental material surfaces

Objectives

The initial adhesion of microorganisms to clinically used dental biomaterials is influenced by physico-chemical parameters like hydrophobicity and pre-adsorption of salivary proteins. Here, polymethyl methacrylate (PMMA), polyethylene (PE), polytetrafluoroethylene (PTFE), silicone (Mucopren soft), silorane-based (Filtek Silorane) and methacrylate-based (Tetric EvoCeram) dental composites, a conventional glassionomer cement as well as cobalt–chromium–molybdenum (Co28Cr6Mo) and titanium (Ti6Al4V) were tested for adsorption of salivary proteins and adhesion of Streptococcus gordonii DL1.

Methods

Wettability of material surfaces precoated with salivary proteins or left in phosphate-buffered saline was determined by the measurement of water contact angles. Amounts of adsorbed proteins were determined directly on material surfaces after biotinylation of amino groups and detection by horseradish peroxidase-conjugated avidin-D. The same technique was used to analyze for the binding of biotinylated bacteria to material surfaces.

Results

The highest amount of proteins (0.18 μg/cm²) adsorbed to hydrophobic PTFE samples, and the lowest amount (0.025 μg/cm²) was detected on silicone. The highest number of S. gordonii (3.2 × 10⁴ CFU/mm²) adhered to the hydrophilic glassionomer cement surface coated with salivary proteins, and the lowest number (4 × 10³ CFU/mm²) was found on the hydrophobic silorane-based composite. Hydrophobicity of pure material surfaces and the number of attached microorganisms were weakly negatively correlated. No such correlation between hydrophobicity and the number of bacteria was detected when surfaces were coated with salivary proteins.

Significance

Functional groups added by the adsorption of specific salivary proteins to material surfaces are more relevant for initial bacterial adhesion than hydrophobicity as a physical property.     

Upper limits of normal for alanine aminotransferase activity in the United States population

Alanine aminotransferase (ALT) is an important test for liver disease, yet there is no generally accepted upper limit of normal (ULN) in the United States. Furthermore, the ability of ALT to differentiate persons with and without liver disease is uncertain. We examined cut-offs for ALT for their ability to discriminate between persons with positive hepatitis C virus (HCV) RNA and those at low risk for liver injury in the U.S. population. Among adult participants in the 1999-2008 U.S. National Health and Nutrition Examination Survey, 259 were positive for serum HCV RNA and 3,747 were at low risk for liver injury (i.e., negative HCV RNA and hepatitis B surface antigen, low alcohol consumption, no evidence of diabetes, and normal body mass index and waist circumference). Serum ALT activity was measured centrally. Maximum correct classification was achieved at ALT = 29 IU/L for men (88% sensitivity, 83% specificity) and 22 IU/L (89% sensitivity, 82% specificity) for women. The cut-off for 95% sensitivity was an ALT = 24 IU/L (70% specificity) for men and 18 IU/L (63% specificity) for women. The cut-off for 95% specificity was ALT = 44 IU/L (64% sensitivity) for men and 32 IU/L (59% sensitivity) for women. The area under the curve was 0.929 for men and 0.915 for women. If the cut-offs with the best correct classification were applied to the entire population, 36.4% of men and 28.3% of women would have had abnormal ALT. CONCLUSION: ALT discriminates persons infected with HCV from those at low risk of liver disease, but would be considered elevated in a large proportion of the U.S. population.     

Effect of a Jurassic oceanic anoxic event on belemnite ecology and evolution

The Toarcian oceanic anoxic event (T-OAE; ∼183 million y ago) is possibly the most extreme episode of widespread ocean oxygen deficiency in the Phanerozoic, coinciding with rapid atmospheric pCO₂ increase and significant loss of biodiversity in marine faunas. The event is a unique past tipping point in the Earth system, where rapid and massive release of isotopically light carbon led to a major perturbation in the global carbon cycle as recorded in organic and inorganic C isotope records. Modern marine ecosystems are projected to experience major loss in biodiversity in response to enhanced ocean anoxia driven by anthropogenic release of greenhouse gases. Potential consequences of this anthropogenic forcing can be approximated by studying analog environmental perturbations in the past such as the T-OAE. Here we present to our knowledge the first organic carbon isotope record derived from the organic matrix in the calcite rostra of early Toarcian belemnites. We combine both organic and calcite carbon isotope analyses of individual specimens of these marine predators to obtain a refined reconstruction of the early Toarcian global exogenic carbon cycle perturbation and belemnite paleoecology. The organic carbon isotope data combined with measurements of oxygen isotope values from the same specimens allow for a more robust interpretation of the interplay between the global carbon cycle perturbation, environmental change, and biotic response during the T-OAE. We infer that belemnites adapted to environmental change by shifting their habitat from cold bottom waters to warm surface waters in response to expanded seafloor anoxia.Climatic and environmental change driven by anthropogenic greenhouse gases is predicted to severely compromise modern-day marine ecosystems through ocean anoxia and possibly ocean acidification (1, 2). Expanded and intensified oxygen minimum zones, accompanied by deposition of organic-rich sediments, have occurred multiple times in the past and are termed oceanic anoxic events (OAEs) (3). The Early Jurassic Toarcian oceanic anoxic event (T-OAE) is among the best-studied of OAEs and represents an interval of global warming (3), high continental weathering intensity (3, 4), and increased atmospheric pCO₂ (5). This event is associated with an enhanced turnover of taxa, enhanced sedimentary organic matter accumulation, and perturbations in the geochemical cycles of essential elements such as carbon, nitrogen, and sulfur and redox-sensitive elements such as molybdenum (3). Cyclostratigraphic studies of the Toarcian sedimentary record suggest a short (<1 My) duration for the event and point to recurring, orbitally paced pulses of rapid environmental change (6–9). The exogenic carbon cycle was globally perturbed as evidenced by a large negative carbon isotope excursion (CIE), which is expressed in marine and terrestrial organic and inorganic carbon in the northern and southern hemispheres (5, 10, 11). Various potential triggers for the T-OAE have been identified. The event coincided with the extensive volcanic activity of the Karoo-Ferrar large igneous province (6–8). Changes in the global carbon cycle through the T-OAE have been hypothesized to be forced by rapid and massive venting of isotopically depleted carbon through the production of thermogenic methane from sill-intruded organic-rich substrates (5) and biogenic methane from ocean floor clathrates (7, 10).Constraining the causes and magnitude of the observed changes in the carbon cycle relies on analytical results from the sedimentary record. Major obstacles for these reconstructions arise because the commonly analyzed bulk samples always represent mixtures of different phases, which may also have been affected by postdepositional alteration. Samples of macrofossil calcite may occur only sparsely and are isotopically more heterogeneous than bulk materials, and signals can be complicated by habitat and vital effects. Macrofossil calcite can, however, be assessed for its preservation state and carry significant information about environmental change and the faunal response to it. For the Jurassic and Cretaceous, the bullet-shaped fossilized remains (calcite rostra) of belemnites, extinct marine predatory cephalopods, are one of the prime sources for marine paleoenvironmental reconstruction. The globally observed early Toarcian negative CIE, which is well known from bulk organic and carbonate carbon isotope records, is either small or absent in the calcite of the rostra (12, 13). This missing expression of the negative CIE in belemnite calcite has led some researchers to question whether the T-OAE has been a climatic event of global extent (12, 13).Isotopic investigations of belemnites have so far only focused on the inorganic matrix of the rostra (12–14). The isotopic composition of the organic matrix, which is embedded in the calcite of the rostrum, has previously not been studied, even though its presence has been known for several decades (15, 16). The organic matter in belemnite rostra can provide complementary information about the animal’s habitat and mode of life. In this study we fill this gap by the analysis of the cogenetic organic and inorganic carbon of individual belemnite rostra. The rostra are derived from the Cleveland Basin (Yorkshire, United Kingdom), a subbasin of the epicontinental Laurasian Seaway with water depths of ∼100 m during the early Toarcian (17) (Fig. 1). Using our newly generated organic carbon isotope data in combination with isotopic data from the calcite of individual rostra, we reassess the paleoenvironmental significance of the isotopic composition of rostral calcite. We suggest a solution to the apparent paradox of the missing negative CIE in the calcite of the rostra by incorporating the ecological and evolutionary response of belemnites to bottom water anoxia into the interpretation of the isotope data.Open in a separate windowFig. 1.Paleogeography of the Laurasian Seaway (or Viking Corridor), modified from ref. 17. Sampling location is marked by a yellow star.     

Injury and death associated with hospital bed side-rails: reports to the US Food and Drug Administration from 1985 to 1995.

OBJECTIVES: Hospital bed side-rails, while intended for patient protection, can contribute to injury and death. Reports to the Food and Drug Administration (FDA) of hospital bed side-rail entrapment have increased. In this paper entrapment cases are reviewed and the population potentially at risk identified. METHODS: FDA's database was searched for events involving hospital beds from January 1985 to August 1995 and entrapment cases were identified. RESULTS: Of 111 entrapments, 65% were associated with death and 23% with injury. CONCLUSIONS: Advanced age, female sex, low body weight, and cognitive impairment may be associated with increased risk. Preventive measures are detailed.