The genes encoding the three terminal enzymes in the threonine biosynthetic pathway, homoserine dehydrogenase (hom), homoserine kinase (thrB) and threonine synthase (thrC) have been isolated from Corynebacterium glutamicum. The C. glutamicum hom and thrB genes were subcloned on a 3.6 kb SalI-generated chromosomal fragment. The C. glutamicum thrC gene was shown not to be linked to the hom-thrB locus. L-methionine represses the cloned homoserine dehydrogenase and homoserine kinase similar to that of the chromosomally encoded hom and thrB gene products. Northern hybridization analysis demonstrates that this repression is mediated at the level of transcription and that hom-thrB represents an operon in C. glutamicum.
Scrap vehicle tire chips were used as packing material for sequential anaerobic-aerobic biofilm reactors to remove persistent chlorinated hydrocarbons. Adsorption capacity of scrap tires was greater under acidic conditions than under basic conditions. However, it was only approximately 0.04 to 0.3% of that of activated carbon. The amount of biomass that attached to the surface of scrap tires was 3.16 and 3.72 mg volatile suspended solids/cm 2 after 14 and 37 days, respectively. Two laboratory-scale, down-flow anaerobic-aerobic biofilm reactors packed with tire chips were operated to remove 2,4dichlorophenol (OCP) and 4-chlorophenol (CP). More than 98% of OCP was dchalogenated to CP in the anaerobic reactor, 70 to 98% of which was subsequently degraded in the aerobic reactor. Scrap tires did not cause any operational problems when used as biofilter media. Water Environ. Res., 71, 363 (1999).
Objective
Human papillomavirus testing by self-sampling and urine sampling might be alternatives to Papanicolaou test (Pap test) for cervical cancer screening (CCS), and may increase compliance and adherence thereto. The present study aimed to explore satisfaction and preferences for cervical screening modalities among Korean women.
Methods
In total, 732 women aged between 20 and 69 years responded to a questionnaire designed to survey the women's perceived satisfaction for the 3 CCS modalities: clinician-collected Pap test, self-collected vaginal sampling (self-sampling) and urine sampling.
Results
Overall satisfaction was significantly higher with both the self-sampling and urine sampling than the clinician-collected Pap test (odds ratio [OR]=2.01; 95% confidence interval [CI]=1.48–3.00 and OR=2.47; 95% CI=1.75–3.48, respectively). Psychological distress, including embarrassment, pain, anxiety, discomfort, and stress, with self-sampling and urine sampling were significantly lower than that with the Pap test. 52% of participants reported preferences for self-sampling in the next screening round.
Conclusions
Korean women were more likely to report satisfaction with alternative modalities (self-sampling and urine sampling) for CCS in comparison to the Pap test. This suggests that self-collected modalities may help with improving CCS uptake rates by eliminating burden related with the Pap test. However, further studies for test accuracy and cost-effective analysis of the alternative modalities should be conducted in order to apply CCS.
The effects of electron donor and toxic materials on the activity of SRB (sulfate reducing bacteria) were evaluated to ensure the efficient treatment of electroplating wastewater using an anaerobic batch test. The maximum utilization rate of glucose by SRB was slightly slower than that of lactate and acetate, but the affinity of glucose on the SRB was similar to that of the acetate and the lactate. The concentration of carbon source required to reduce 2,000mg/L of sulfate, that is the common concentration of sulfate in the raw electroplating wastewater, was estimated as about 2,200mg COD/L. The efficiency of carbon source for the reduction of sulfate was the highest at around 0.33 of the COD/SO4−2 ratio, but the rate of sulfate reduction was increased according to the increase of COD/SO4−2 ratio ranged from 0.18 to 1.21. Inhibition of copper on the activity of SRB was able to explain using non-competitive inhibition model, and IC50 for copper, that is the concentration causing 50% inhibition of SRB activity, was about 100mg/L of copper. The inhibition of chromium(VI) on the activity of SRB was observed as a mixed inhibition, but the degree of inhibition on the activity of SRB was only about 15% at 130mg/L of the chromium(VI). The inhibitory effect on the SRB caused by 10mg/L of cyanide compound was over 30% of the control, and it was rapidly increased with the cyanide concentration. That could be explained using uncompetitive inhibition model, and IC50 was estimated as about 20mg/L.
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