Thermosensitivity of the Saccharomyces cerevisiae gpp1gpp2 double deletion strain can be reduced by overexpression of genes involved in cell wall maintenance

A Saccharomyces cerevisiae strain in which the GPP1 and GPP2 genes, both encoding glycerol-3-phosphate phosphatase isoforms, are deleted, displays both osmo- and thermosensitive (ts) phenotypes. We isolated genes involved in cell wall maintenance as multicopy suppressors of the gpp1gpp2 ts phenotype. We found that the gpp1gpp2 strain is hypersensitive to cell wall stress such as treatment with β-1,3-glucanase containing cocktail Zymolyase and chitin-binding dye Calcofluor-white (CFW). Sensitivity to Zymolyase was rescued by overexpression of SSD1, while CFW sensitivity was rescued by SSD1, FLO8 and WSC3-genes isolated as multicopy suppressors of the gpp1gpp2 ts phenotype. Some of the isolated suppressor genes (SSD1, FLO8) also rescued the lytic phenotype of slt2 deletion strain. Additionally, the sensitivity to CFW was reduced when the cells were supplied with glycerol. Both growth on glycerol-based medium and overexpression of SSD1, FLO8 or WSC3 had additive suppressing effect on CFW sensitivity of the gpp1gpp2 mutant strain. We also confirmed that the internal glycerol level changed in cells exposed to cell wall perturbation. © 2007 Springer-Verlag

Assessment of portal venous index as a non-invasive method for diagnosing liver fibrosis in patients with chronic hepatitis C

CONTEXT: Hepatitis C is an important cause of chronic liver disease worldwide. The grading of hepatic fibrosis in chronic hepatitis C is important for better clinical management. However, until now, liver biopsy is the only test accepted for this purpose, despite their contraindications and complications. New methods for non-invasive assessment of hepatic fibrosis are under investigation. One proposal is the Doppler ultrasound, as a non-invasive, widely available and inexpensive. OBJECTIVE: To compare Doppler parameters of portal vein in patients with chronic hepatitis C with a healthy control group and to correlate these parameters with fibrosis degree obtained by liver biopsy. METHODS: Fifty patients with chronic hepatitis C submitted to liver biopsy and 44 healthy controls had Doppler of the portal vein performed, with the calculation of the portal venous index. We conducted a comparison between the averages of the two groups of portal venous index. For the correlation between portal venous index and fibrosis was employed the Spearman test. RESULTS: There was a difference between the average portal venous index between controls (0.33 ± 0.07) and patients (0.23 ± 0.09) with P<0.001. No difference was observed between the portal venous index in patients with chronic hepatitis C who have significant fibrosis or not. The correlation between the portal venous index and fibrosis degree was reverse and moderate (r =-0.448 P<0.001). The area under the ROC curve was 78.4% (95% CI: 68.8% to 88%). The cutoff for the portal venous index was 0.28 with sensitivity of 73.5% and specificity of 71.1%. CONCLUSION: The portal venous index was useful in distinguishing healthy patients from patients with CHC. However, there was no significant difference in the quantification of degree of fibrosis

Intrapupal temperature variation during Er,Cr: YSGG enamel irradiation on carries prevention

Studies have shown the cariostatic effect of Er,Cr:YSGG (2.78 mm) laser irradiation on human enamel and have suggested its use on caries prevention. However there are still no reports on the intrapulpal temperature increase during enamel irradiation using parameters for caries prevention. The aim of this in vitro study was to evaluate the temperature variation in the pulp chamber during human enamel irradiation with Er,Cr:YSGG laser at different energy densities. Fifteen enamel blocks obtained from third molars (3 x 3 x 3 mm) were randomly assigned to 3 groups (n=5): G1 - Er,Cr:YSGG laser 0.25 W, 20 Hz, 2.84 J/cm², G2 - Er,Cr:YSGG laser 0.50 W, 20 Hz, 5.68 J/cm², G3 - Er,Cr:YSGG laser 0.75 W, 20 Hz, 8.52 J/cm². During enamel irradiation, two thermocouples were fixed in the inner surface of the specimens and a thermal conducting paste was used. One-way ANOVA did not show statistically significant difference among the experimental groups (a=0.05). There was intrapulpal temperature variation <0.1ºC for all irradiation parameters. In conclusion, under the tested conditions, the use of Er,Cr:YSGG laser with parameters set for caries prevention lead to an acceptable temperature increase in the pulp chamber