Dermal melanin concentration of yellow perch Perca flavescens in relation to water transparency.

A positive relationship was observed between Secchi disc depth and dermal melanin concentration in yellow perch Perca flavescens sampled from 11 humic lakes located on the Canadian Shield in southern Quebec (Canada). Secchi disc depth explained 23% of the variations of dermal melanin concentration. Secchi disc depth and thus water transparency appear to have a positive influence on melanin production in the dermis of P. flavescens.

The epidemiology of tuberculosis in Ottawa, Canada, 1995-2004.

BACKGROUND: In Ottawa (population 774,072), active tuberculosis (TB) cases are reported to Ottawa Public Health. There has been no comprehensive local epidemiological analysis to date. We report the epidemiology of TB in Ottawa and identify areas of improvement. METHODS: We reviewed TB cases reported to the Reportable Disease Information System from 1995 to 2004 to determine epidemiological characteristics, drug resistance, use of directly observed treatment (DOT) and rates of human immunodeficiency virus (HIV) co-infection. RESULTS: A total of 584 TB cases (79% foreign-born) were analyzed (average annual incidence 7.5/100,000). Anatomical site of disease followed national trends, with 58% being pulmonary TB. DOT was applied in 49% of total cases. Culture results were available for 385 (66%) and resistance was found in 46 (12%) cases. HIV testing results were available for only 139 cases: 24% were positive. CONCLUSION: Overall, Ottawa TB rates are slightly higher than national rates, yet they reflect national trends. The surveillance data were imperfect, with poor or no recording of aboriginal origin, adverse events and treatment outcomes. Reported resistance patterns may be underestimated, as only 66% had cultures. HIV testing was underutilized. Given the high mortality with TB-HIV co-infection, testing should be routine. Correcting these limitations will improve surveillance data and TB control in the future.

Characterization of Staphylococcus aureus mutants expressing reduced susceptibility to common house-cleaners.

AIMS: To characterize mutants of Staphylococcus aureus expressing reduced susceptibility to house cleaners (HC), assess the impact of the alternative sigma factor SigB on HC susceptibility, and determine the MIC of clinical methicillin-resistant S. aureus (MRSA) to a HC. METHODS AND RESULTS: Susceptibility to HC, HC components, H2O2, vancomycin and oxacillin and physiological parameters were determined for HC-reduced susceptibility (HCRS) mutants, parent strain COL and COLsigB::kan. HCRS mutants selected with three HC expressed reduced susceptibility to multiple HC, HC components, H2O2 and vancomycin. Two unique HCRS mutants also lost the methicillin resistance determinant. In addition, all HCRS mutants exhibited better growth at two temperatures, and one HCRS mutant expressed reduced carotenoid production. COLsigB::kan demonstrated increased susceptibility to all HC and many HC components. sigB operon mutations were not detected in one HCRS mutant background. Of 76 clinical MRSA, 20 exhibited reduced susceptibility to a HC. CONCLUSIONS: HCRS mutants demonstrate altered susceptibility to multiple antimicrobials. While sigB is required for full HC resistance, one HCRS mechanism does not involve sigB operon mutations. Clinical MRSA expressing reduced susceptibility to a common HC were detected. SIGNIFICANCE AND IMPACT OF THE STUDY: This study suggests that HCRS mutants are not protected against, nor selected by, practical HC concentrations.

Activation of rat macrophages by Betafectin PGG-glucan requires cross-linking of membrane receptors distinct from complement receptor three (CR3).

PGG-glucan (Betafectin) is a soluble, highly purified yeast (1,3)-beta-glucan with broad anti-infective and immunomodulatory activities. These studies evaluated the ability of PGG-glucan to directly elicit O2- and tumor necrosis factor alpha (TNF-alpha) production by rat leukocytes in vitro. Particulate beta-glucan stimulated O2- production by the rat NR8383 alveolar macrophage cell line and resident rat peritoneal macrophages, but soluble PGG-glucan did not. In contrast, presentation of PGG-glucan to cells after covalent immobilization to a plastic surface caused a direct stimulation of O2- and TNF-alpha production. The O2- response of rat leukocytes to immobilized PGG-glucan was inhibited by soluble PGG-glucan, indicating that cellular responses to both immobilized and soluble PGG-glucan occur via common cell surface receptors. Because complement receptor type three (CR3) has been proposed as a beta-glucan receptor on human leukocytes, NR8383 cells were evaluated for the presence of CR3. Indirect immunofluorescence and flow cytometric analysis showed that despite being responsive to both particulate and immobilized beta-glucans, NR8383 cells expressed no detectable CR3. These results indicate that the beta-glucan receptors on NR8383 cells are not CR3 and suggest that physical presentation plays an important role in inducing pro-inflammatory leukocyte responses to PGG-glucan.

Fecundity of infertile women with minimal or mild endometriosis and women with unexplained infertility. The Canadian Collaborative Group on Endometriosis.

OBJECTIVE: To assess whether infertile women with minimal or mild endometriosis have lower fecundity than women with unexplained infertility. DESIGN: Prospective cohort study. SETTING: Twenty-three infertility clinics across Canada. PATIENT(S): Three hundred thirty-one infertile women aged 20-39 years. INTERVENTION(S): Diagnostic laparoscopy for infertility. Infertile women with minimal or mild endometriosis (n = 168) were compared with women with unexplained infertility (n = 263). Both groups were managed expectantly. The women were followed up for 36 weeks after the laparoscopy or, for those who became pregnant, for up to 20 weeks of the pregnancy. MAIN OUTCOME MEASURE(S): Fecundity refers to the probability of becoming pregnant in the first 36 weeks after laparoscopy and carrying the pregnancy for > or = 20 weeks. The fecundity rate is the number of pregnancies per 100 person-months. RESULT(S): Fecundity was 18.2% in infertile women with minimal or mild endometriosis and 23.7% in women without endometriosis (log-rank test). The fecundity rate was 2.52 per 100 person-months in women with endometriosis and 3.48 per 100 person-months in women with unexplained infertility. The crude and adjusted fecundity rate ratios were 0.72 and 0.83 (95% confidence interval = 0.53-1.32), respectively. CONCLUSION(S): The fecundity of infertile women with minimal or mild endometriosis is not significantly lower than that of women with unexplained infertility.

A randomized, double-blind, placebo-controlled study on the effect of conjugated estrogens on skin thickness.

OBJECTIVE: Our purpose was to assess the potential benefit of therapy with conjugated estrogens therapy on skin thickness in postmenopausal women. STUDY DESIGN: Sixty postmenopausal women were randomly allocated to receive conjugated estrogens or placebo treatment for 12 months. Neither participants nor investigators were aware of the group allocation. Skin thickness was measured by ultrasonography at baseline and after 6 to 12 months of treatment. Histologic changes were evaluated by skin biopsy at baseline and after 12 months' treatment. Quality of life and adverse events were recorded at each visit and at the end of treatment. RESULTS: Treatment with conjugated estrogens for 12 months significantly increases, at the level of the right great trochanter, the thickness of the skin (p < 0.01), as assessed by ultrasonography, and of the dermis (p < 0.05), as assessed by skin biopsy. No statistically significant difference was observed in the control population. Quality of life was reported to be improved (p < 0.05) in women treated with estrogen compared with those in the placebo group. CONCLUSION: The results may help postmenopausal women to better appraise the benefits of estrogen replacement therapy, and they provide further evidence of the potential of conjugated estrogens in preventing skin aging.

Swallowing disturbances associated with drooling in cerebral-palsied children.

The oral stage of swallowing was studied in two groups of 10 cerebral-palsied (CP) children (one drooled and the other did not), and 10 normal children, aged six to 14 years. Small amounts of liquid (0.5 to 1mL) were placed under the tongue or behind the lower lip and intra-oral pressure was measured during the suction and propulsion stages. The CP children who drooled showed no abnormality in the propulsion of liquid towards the pharynx, but all showed abnormal suction of liquid onto the tongue. The difficulty seems to be associated with three types of disturbance: incomplete lip-closure during swallowing, low suction-pressure and prolonged delay between the suction and propelling stages.

The metabolism of ethanol-derived acetaldehyde by alcohol dehydrogenase (EC 1.1.1.1) and aldehyde dehydrogenase (EC 1.2.1.3) in Drosophila melanogaster larvae.

Both aldehyde dehydrogenase (ALDH, EC 1.2.1.3) and the aldehyde dehydrogenase activity of alcohol dehydrogenase (ADH, EC 1.1.1.1) were found to coexist in Drosophila melanogaster larvae. The enzymes, however, showed different inhibition patterns with respect to pyrazole, cyanamide and disulphiram. ALDH-1 and ALDH-2 isoenzymes were detected in larvae by electrophoretic methods. Nonetheless, in tracer studies in vivo, more than 75% of the acetaldehyde converted to acetate by the ADH ethanol-degrading pathway appeared to be also catalysed by the ADH enzyme. The larval fat body probably was the major site of this pathway.

Induction of alcohol dehydrogenase by ethanol in Drosophila melanogaster.

When Drosophila melanogaster larvae were fed a defined fat-free, low sucrose medium, alcohol dehydrogenase (ADH) was increased to a higher activity with a moderate, nontoxic level of ethanol (2.5% vol/vol) within 5 h. Ethanol-stimulated increases in ADH activity and cross-reacting material in late third-instar larvae were paralleled by increases in the larval ADH mRNA as indicated by dot blot analysis. Northern blot observations indicated that both adult and larval ADH messages were increased by dietary ethanol. The increased levels of the ADH mRNA transcribed from the proximal and distal promoters of ethanol-fed larvae argue that the induction is a consequence of elevated levels of mRNA, not a result of changes in enzyme stability or synthesis. To determine whether the induction is of nutritional significance to larvae, the rate of flux from ethanol to lipid was estimated in control larvae and larvae that were pre-fed ethanol. Flux changes occurred; the rate of incorporation of [14C]ethanol into body lipid showed a strong association with larval ADH activity. Because the induced increase in larval ADH activity did not extend into the adult stage and attempts to stimulate ADH activity by exposing adults to ethanol were unsuccessful, the modulation of ADH activity by dietary ethanol may be a mechanism by which larvae utilize environmental ethanol as a resource, especially when free sugar levels are low. In addition, ADH in larvae is postulated to perform a second, nonethanol function that expedites the conversion of sugars to lipid when habitats are low in fats, low in ethanol and high in sugars.

The effect of dietary ethanol on the composition of lipids of Drosophila melanogaster larvae.

At a moderate concentration (2.5%, v/v) dietary ethanol reduced the chain length of total fatty acids (FA) and increased the desaturation of short-chain FA in Drosophila melanogaster larvae with a functional alcohol dehydrogenase (ADH). The changes in length in total FA were postulated to be due to the modulation of the termination specificity of fatty acid synthetase. Because the ethanol-stimulated reduction in the length of unsaturated FA was blocked by linoleic acid, it was thought to reflect the properties of FA 9-desaturase. Although the ethanol-stimulated reduction in chain length of unsaturated FA was also observed in ADH-null larvae, ethanol promoted an increase in the length of total FA of the mutant larvae. Thus, the ethanol-stimulated change in FA length was ADH dependent but the ethanol effect on FA desaturation was not. Ethanol also stimulated a decrease in the relative amount of phosphatidylcholine and an increase in phosphatidylethanolamine. Because similar ethanol-induced changes have been found in membrane lipids of other animals, ethanol may alter the properties of membranes in larvae. It is proposed that ethanol tolerance in D. melanogaster may be dependent on genes that specify lipids that are resistant to the detrimental effects of ethanol.

Dietary ethanol and lipid synthesis in Drosophila melanogaster.

When cultured on a defined diet, ethanol was an efficient substrate for lipid synthesis in wild-type Drosophila melanogaster larvae. At certain dietary levels both ethanol and sucrose could displace the other as a lipid substrate. In wild-type larvae more than 90% of the flux from ethanol to lipid was metabolized via the alcohol dehydrogenase (ADH) system. The ADH and aldehyde dehydrogenase activities of ADH were modulated in tandem by dietary ethanol, suggesting that ADH provided substrate for lipogenesis by degrading ethanol to acetaldehyde and then to acetic acid. The tissue activity of catalase was suppressed by dietary ethanol, implying that catalase was not a major factor in ethanol metabolism in larvae. The activities of lipogenic enzymes, sn-glycerol-3-phosphate dehydrogenase, fatty acid synthetase (FAS), and ADH, together with the triacylglycerol (TG) content of wild-type larvae increased in proportion to the dietary ethanol concentration to 4.5% (v/v). Dietary ethanol inhibited FAS and repressed the accumulation of TG in ADH-deficient larvae, suggesting that the levels of these factors may be subject to a complex feedback control.

Regulation of sn-glycerol-3-phosphate dehydrogenase in Drosophila melanogaster larvae by dietary ethanol and sucrose.

Dietary sucrose and ethanol are potent modulators of sn-glycerol-3-phosphate dehydrogenase (GPDH) in the third instar larvae of Drosophila melanogaster. When added to modified Sang's medium C, 428 mM ethanol and 146 mM sucrose each increased the GPDH tissue activity more than 90% and GPDH cross-reacting material (CRM) more than 50% over the levels found in larvae fed the 14.6 mM sucrose control diet. When fed together, ethanol and sucrose exerted synergetic effects on GPDH activity and CRM. The activity of glycerol-3-phosphate oxidase was also stimulated by dietary ethanol and sucrose, indicating that the glycerol-3-phosphate cycle was operating in the larvae. Dietary ethanol caused similar shifts in the NADH:NAD+ ratio in wild-type and Gpdh null larvae, suggesting that the maintenance of the cofactor equilibrium is not the primary function of GPDH in larvae. Increases in triacylglycerol content associated with the administration of ethanol and sucrose to larvae suggested that the formation of glycerol-3-phosphate for use in lipid synthesis is an important function of GPDH in larvae. Because ethanol is a constituent of the natural diet of D. melanogaster, nutritional modulation of GPDH is postulated to be an important aspect of the adaptation of the species to its environment.

The effects of taxol on the organization of the cytoskeleton in cultured ovarian granulosa cells.

Exposure of ovarian granulosa cells to taxol, a potent microtubule assembly promoting and stabilization agent, results in a time and dose-dependent alteration in the organization of cytoplasmic filaments (microtubules, microfilaments, intermediate filaments) and organelles. Transmission electron microscopy and fluorescence microscopy are used in conjunction with various antimitotic drugs to evaluate the action of taxol on suspension and monolayer cultures. Taxol treatment (1.0 microM) of freshly isolated suspended cells for 4 h leads to the formation of multiple bundles of microtubules emanating from a single centrosomal organizing center. Within 4 h after addition to monolayer cultures, 1.0 microM taxol induces a lateral aggregation of microtubules which, by 12 to 24 h of treatment, results in the appearance of dense bundles of tightly-packed microtubules located near the centrosome, close to the outer nuclear envelope, and at peripheral cytoplasmic sites. By electron microscopy, both lateral and end-on associations between bundled microtubules and the nuclear envelope are apparent. During the course of taxol-induced bundling, intermediate filaments are altered from a normally dispersed fibrous network into perinuclear aggregates. Microtubule bundling is also associated with a rearrangement of actin filaments from stress fibers into a marginal distribution, and actin appears to be excluded from sites of bundle formation. When granulosa cells are treated with equivalent concentrations of the microtubule-disrupting drugs, colchicine or nocodazole, either before or during taxol treatment, bundle formation is prevented suggesting that an intact microtubule network is required for taxol-induced bundling. Colchicine, but not nocodazole, is able to reverse the effects of taxol on bundle formation. The data suggest that the cellular distribution of cytoplasmic organelles, intermediate filaments, and microfilaments are regulated by the cytoplasmic microtubule complex.