A simple method for counting Staphylococcus aureus in swimming pool water

Staphylococcus aureus counts from swimming pool water were determined by the membrane filtration technique. Water samples were passed through a membrane filter and then put on Baird-Parker media. After incubation, the filters were transferred to nutrient agar, and incubated at 37 degrees C, for 3 h. After removal of the filters, the plates were incubated at 60 degrees C for 2 h. An overlay of toluidine blue agar was added and the plates reincubated for 4 h at 37 degrees C. The formation of thermonuclease correlated with the formation of coagulase, and the results indicated that Staphylococcus aureus could be present in swimming pool water without the presence of either coliform or faecal coliform bacteria.     

Membrane filtration differentiation of E. coli from coliforms in the examination of water

A membrane filter-Endo agar method for enumerating Escherichia coli as distinct from other coliforms in drinking water was developed. Membranes containing coli-form colonies are transferred to nutrient agar containing 4-methyl umbelliferyl-β-d-glucuronide (MUG) and incubated at 35°C for 4 h. The MUG is hydrolyzed by the glucuronidase of E. coli and the fluorogenic product is visualized. The method recovered 98% of E. coli without false positives and is proposed as an additional test in routine water examination for the detection of pollution.     

The Effect of Alcohols on Growth and Lipase Formation by Staphylococcus aureus

S ummary . The growth of Staphylococcus aureus 111 was inhibited by aliphatic alcohols. The extent of inhibition by primary n -alcohols increased with the elongation of the chain. Secondary alcohols were less inhibitory than the corresponding primary alcohols. The inhibitory effect was influenced by the distance of the hydroxyl group from the end of the carbon chain. When the alcohols were added to the medium in sub-inhibitory amount, enzyme synthesis by the bacteria was decreased, but there was no demonstrable inhibition of enzyme already formed.     

A double-selective tissue culture system for isolation of wild-type poliovirus from sewage applied in a long-term environmental surveillance

We describe a simple, cost-efficient, double-selective method for isolation of wild-type poliovirus from sewage samples containing vaccine polioviruses and other enteroviruses, with a detection limit of 18 to 50 PFU per 1 to 2 liters of sewage. By this method we were able to process 1,700 sewage samples collected between 1991 and 1996, from which 10,472 plaques were isolated, 41 of them being identified as wild-type polioviruses.     

The effect of early treatment by cerivastatin on the serum level of C-reactive protein,interleukin-6, and interleukin-8 in patients with unstable angina and non-Q-wave myocadial infarction

The aim of our study was to evaluate whether a single dose of cerivastatin at the time of admission of patients with unstable angina pectoris (UAP) or non-Q-wave myocardial infarction (NQMI) can influence the serum level of C-reactive protein (CRP), interleukin-6 (IL-6) and interleukin-8 (IL-8) 24 h later. Forty-four patients with rest chest pain and subendocardial ischemia on ECG were randomized to receive cerivastatin 0.3 mg at the time of admission (group C+) to standard therapy or to remain just on standard therapy (group C–). Blood samples for determination of troponin I (TI), CRP, IL-6 and IL-8 were collected at admission (entry level) and 24 h later (final level). Patients with non-physiological baseline levels of TI, as well as patients with progression to Q wave MI were excluded. All baseline, clinical and demographic data and final values of TI were comparable in the two groups. In patients treated with cerivastatin (group C+, n = 13) we observed decrease in the CRP level (–6.73 ± 3.93 mg/L); on the other hand, in group C– (n = 17) the CRP level increased (+7.92 ± 2.77 mg/L, p = 0.004). Similar differences were observed also in IL-6: in group C+ the level was significantly reduced as compared with the increase in group C– (–0.76 ± 0.52 vs. 4.58 ± 1.49 ng/L, p = 0.005). The level of IL-8 was not affected. Our results suggest that early treatment with cerivastatin can decrease the serum level of CRP and IL-6 in patients with UAP/NQMI; this might positively influence their prognosis. Nevertheless, further studies are needed to support this hypothesis.     

Circulating Concentrations of Vitamin B6 and Kidney Cancer Prognosis: A Prospective Case-Cohort Study

Prospective cohort studies have found that prediagnostic circulating vitamin B6 is inversely associated with both risk of kidney cancer and kidney cancer prognosis. We investigated whether circulating concentrations of vitamin B6 at kidney cancer diagnosis are associated with risk of death using a case-cohort study of 630 renal cell carcinoma (RCC) patients. Blood was collected at the time of diagnosis, and vitamin B6 concentrations were quantified using LC-MS/MS. Hazard ratios (HR) and 95% confidence intervals (CI) were calculated using Cox regression models. After adjusting for stage, age, and sex, the hazard was 3 times lower among those in the highest compared to the lowest fourth of B6 concentration (HR_4vs1 0.33, 95% CI [0.18, 0.60]). This inverse association was solely driven by death from RCC (HR_4vs1 0.22, 95% CI [0.11, 0.46]), and not death from other causes (HR_4vs1 0.89, 95% CI [0.35, 2.28], p-interaction = 0.008). These results suggest that circulating vitamin B6 could provide additional prognostic information for kidney cancer patients beyond that afforded by tumour stage.     

Products of the Escherichia coli acid fitness island attenuate metabolite stress at extremely low pH and mediate a cell density-dependent acid resistance

Escherichia coli has an ability, rare among the Enterobacteriaceae, to survive extreme acid stress under various host (e.g., human stomach) and nonhost (e.g., apple cider) conditions. Previous microarray studies have exposed a cluster of 12 genes at 79 centisomes collectively called an acid fitness island (AFI). Four AFI genes, gadA, gadX, gadW, and gadE, were already known to be involved in an acid resistance system that consumes an intracellular proton through the decarboxylation of glutamic acid. However, roles for the other eight AFI gene products were either unknown or subject to conflicting findings. Two new aspects of acid resistance are described that require participation of five of the remaining eight AFI genes. YhiF (a putative regulatory protein), lipoprotein Slp, and the periplasmic chaperone HdeA protected E. coli from organic acid metabolites produced during fermentation once the external pH was reduced to pH 2.5. HdeA appears to handle protein damage caused when protonated organic acids diffuse into the cell and dissociate, thereby decreasing internal pH. In contrast, YhiF- and Slp-dependent systems appear to counter the effects of the organic acids themselves, specifically succinate, lactate, and formate, but not acetate. A second phenomenon was defined by two other AFI genes, yhiD and hdeD, encoding putative membrane proteins. These proteins participate in an acid resistance mechanism exhibited only at high cell densities (>10(8) CFU per ml). Density-dependent acid resistance does not require any demonstrable secreted factor and may involve cell contact-dependent activation. These findings further define the complex physiology of E. coli acid resistance.     

Comprehensive evaluation of one-carbon metabolism pathway gene variants and renal cell cancer risk

Introduction

Folate and one-carbon metabolism are linked to cancer risk through their integral role in DNA synthesis and methylation. Variation in one-carbon metabolism genes, particularly MTHFR, has been associated with risk of a number of cancers in epidemiologic studies, but little is known regarding renal cancer.

Methods

Tag single nucleotide polymorphisms (SNPs) selected to produce high genomic coverage of 13 gene regions of one-carbon metabolism (ALDH1L1, BHMT, CBS, FOLR1, MTHFR, MTR, MTRR, SHMT1, SLC19A1, TYMS) and the closely associated glutathione synthesis pathway (CTH, GGH, GSS) were genotyped for 777 renal cell carcinoma (RCC) cases and 1,035 controls in the Central and Eastern European Renal Cancer case-control study. Associations of individual SNPs (n = 163) with RCC risk were calculated using unconditional logistic regression adjusted for age, sex and study center. Minimum p-value permutation (Min-P) tests were used to identify gene regions associated with risk, and haplotypes were evaluated within these genes.

Results

The strongest associations with RCC risk were observed for SLC19A1 (P_min-P = 0.03) and MTHFR (P_min-P = 0.13). A haplotype consisting of four SNPs in SLC19A1 (rs12483553, rs2838950, rs2838951, and rs17004785) was associated with a 37% increased risk (p = 0.02), and exploratory stratified analysis suggested the association was only significant among those in the lowest tertile of vegetable intake.

Conclusions

To our knowledge, this is the first study to comprehensively examine variation in one-carbon metabolism genes in relation to RCC risk. We identified a novel association with SLC19A1, which is important for transport of folate into cells. Replication in other populations is required to confirm these findings.     

Comprehensive analysis of 5-aminolevulinic acid dehydrogenase (ALAD) variants and renal cell carcinoma risk among individuals exposed to lead

Background

Epidemiologic studies are reporting associations between lead exposure and human cancers. A polymorphism in the 5-aminolevulinic acid dehydratase (ALAD) gene affects lead toxicokinetics and may modify the adverse effects of lead.

Methods

The objective of this study was to evaluate single-nucleotide polymorphisms (SNPs) tagging the ALAD region among renal cancer cases and controls to determine whether genetic variation alters the relationship between lead and renal cancer. Occupational exposure to lead and risk of cancer was examined in a case-control study of renal cell carcinoma (RCC). Comprehensive analysis of variation across the ALAD gene was assessed using a tagging SNP approach among 987 cases and 1298 controls. Occupational lead exposure was estimated using questionnaire-based exposure assessment and expert review. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using logistic regression.

Results

The adjusted risk associated with the ALAD variant rs8177796^CT/TT was increased (OR = 1.35, 95%CI = 1.05–1.73, p-value = 0.02) when compared to the major allele, regardless of lead exposure. Joint effects of lead and ALAD rs2761016 suggest an increased RCC risk for the homozygous wild-type and heterozygous alleles (^GGOR = 2.68, 95%CI = 1.17–6.12, p = 0.01; ^GAOR = 1.79, 95%CI = 1.06–3.04 with an interaction approaching significance (p_int = 0.06).. No significant modification in RCC risk was observed for the functional variant rs1800435^(K68N). Haplotype analysis identified a region associated with risk supporting tagging SNP results.

Conclusion

A common genetic variation in ALAD may alter the risk of RCC overall, and among individuals occupationally exposed to lead. Further work in larger exposed populations is warranted to determine if ALAD modifies RCC risk associated with lead exposure.     

A model of the perception of area.

A psychophysical experiment was performed to measure the ability of human observers to compare the areas of two geometrical figures (squares and rectangles). The results show a systematic overestimation of rectangle area with respect to that of the squares. A formal model of area perception and its consequent estimation is proposed, which is based on the concept of an 'image function'. It assumes that not the original figure but some specific isocline defined on the image function surface determines area perception. The systematic error observed in the experiment is explained by the model. We discuss the role of different definitions of the image function as well as its parameters on the model performance.