[Comparative study of single strand conformation polymorphism of 4.5S RNA gene in enterobacteria]

A recently developed technique, non-isotopic single strand conformation polymorphism analysis (PCR-SSCP), was applied to study the conserved feature of 4.5S RNA gene in enterobacteria. The 4.5S RNA gene was amplified by the polymerase chain reaction, using the template DNA extracted respectively from five strains of Escherichia coli and three strains of different genera in Enterobacteriaceae, i.e. Proteus vulgaris, Serratia marcescens and Enterobacter aerogenes. The PCR products were then carried out SSCP analysis. The experimental results showed that there seemed to be no detectable differences in the size and single strand conformation of 4.5S RNA genes from above strains, except the negative strand conformation of Enterobacter aerogenes. Thus it can be seen that the secondary structures of 4.5S RNA gene in enterobacteria are quite conservative.

Relative estimates of combination weights, decision criteria, and internal noise based on correlation coefficients

A means by which relative combination weights may be determined is described for a signal detection model in which the decision variable is a weighted linear combination of several independent, normally distributed random variables, Xi's. The first theorem presents the correlation between the binary response variables--signal versus no signal--and the component Xi. The second theorem presents a parallel result for the case that additive internal noise is present. Thus in psychophysical experiments, the relative combination weights may be obtained by correlating the observers' responses and the input random variables. Third, three numerical methods which allow the evaluation of the relative magnitude of the decision criterion and the variance of a hypothetical additive internal noise are considered.

[Restriction endonuclease analysis of Pomona serogroup of Leptospira interrogans]

Restriction Endonuclease Analysis (REA) was performed on DNAs from the type strains of the Pomona serogroup of Leptospira interrogans by using EcoRI and HhaI restriction enzyme, and the electrophoretic patterns obtained were compared with patterns obtained from 27 isolates from pig kidneys collected at abattoirs in Victoria, which belong to Pomona serogroup previous identified by MAT. All of the isolates were identified as serovar Pomona.

An experimental study on acupuncture anti-hemorrhagic shock

The effect of acupuncture at Neiguan (P 6) on regulating hemorrhagic shock in 90 rabbits was observed. All the results suggested that acupuncture at Neiguan could raise blood pressure, protect cardiac pump function, correct the disturbance of secretion and metabolism of humoral factors, reduce blood adhesion to normal level and thus achieve anti-hemorrhagic shock. This study has provided scientific basis for expounding the mechanism of acupuncture in anti-shock.

[The comparative analysis of the complications of extracapsular cataract extraction with and without posterior chamber intraocular lens implantation]

Three-hundred and fourteen eyes that underwent extracapsular cataract extraction (ECCE) were analyzed. ECCE with posterior chamber intraocular lens implantation (PC IOL) was performed in 168 eyes and ECCE alone was performed in 146 eyes. The complications and visual acuity were compared in the two groups. The PC IOL group showed a low incidence of complications. In addition, vitreous loss occurred in 2.38%, cystoid macular edema occurred in 0.6%, and visual acuity recovered to 0.5 or better in 97.62% of the eyes. The incidence of complications in the ECCE group was slightly higher. The postoperative visual acuity in the ECCE group was lower than that in PC IOL group.

[Survey and analysis on correlative factors with CHD in 12,468 pupils in Yimeng mountain area]

The risk factors correlated with congenital heart diseases (CHD) in 12,468 pupils in Yimeng mountain area were surveyed and analysed. The morbidity rate of CHD was 3.05%, which was higher than those of other heart diseases; ventricular septal defect (VSD) was more frequent than other types of CHD. The frequency in pupils in city is higher than in rural areas. In 38 cases with CHD, through analysis (1:1) on the risk of single factor and the progressive regression analysis on compound factors, the results showed that the age of pregnant women (> or = 35 years), the job of mother (chemical worker), the history of coryza in pregnancy (within 3 months), the season of birth (August, September), and the family history of malformation are notably correlated with CHD.

Mutagenicity of the human carcinogen treosulphan, and its hydrolysis product, dl-1,2:3,4-diepoxybutane in mammalian cells

The cytotoxicity and mutagenicity of the human carcinogen, treosulphan, and its hydrolysis product, dl-1,2:3,4-diepoxybutane (DEB), were studied in Chinese hamster ovary, AS52, cells. Treosulphan (0.1-1.0 mM) is toxic and mutagenic at the gpt locus. A strong pH dependence was noted. DEB is cytotoxic and mutagenic at a much lower dose (0.025 mM), but these effects were not affected by pH. The results suggest that the toxic and mutagenic effects of treosulphan are mediated by its hydrolysis product DEB, and that the conversion of treosulphan to DEB is highly pH-dependent.

Thermophilic aerobic process for the treatment of slaughterhouse effluents with protein recovery

A pig slaughterhouse effluent was submitted to laboratory runs in order to assess the potential of the thermophilic aerobic process for the treatment of slaughterhouse and meat processing industry effluents with protein recovery. Experiments were conducted at 45 degrees C, 52 degrees C and 58 degrees C with solids retention times of 6, 12, 18, 24 and 30 h in a semi-continuously fed bioreactor. At 45 degrees C and 52 degrees C, over 90% of the Chemical Oxygen Demand (COD) was removed at all retention times investigated. At 58 degrees C, COD decreased by 86%, with the exception of the 6-h retention time. A biomass containing 70% Gross Protein (GP) was recovered. The optimal specific productivity of GP (0.434 mgGP mgCOD(-1) h(-1)) occurred at 52 degrees C with a 6-h retention time. Biokinetic parameters were evaluated by fitting to appropriate mathematical models. Analysis of the GP composition confirmed that the amino acid levels in the recovered biomass meet most animal requirements.

The effect of sodium selenite on cell proliferation and transformation of primary rat tracheal epithelial cells

The effects of sodium selenite (Na2SeO3) on cell proliferation and the development of preneoplastic transformed variants were studied in primary cultures of rat tracheal epithelial cells. Results revealed a biphasic effect of Na2SeO3 on cell proliferation: at concentrations between 6 x 10(-8) and 6 x 10(-6) M, it stimulated and at concentrations of approximately 2 x 10(-5) and above it inhibited cell proliferation (presumably due to toxicity). Nontoxic concentrations of Na2SeO3 (6 x 10(-8) -6 x 10(-7) M) significantly reduced the spontaneous transformation frequency. Transformation induced by the tobacco-specific nitrosamine 4-(methyl-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK) was effectively inhibited by nontoxic as well as toxic concentrations of Na2SeO3. Treatment of cultures with Na2SeO3 after cessation of NNK exposure, i.e. during the selection period, also significantly reduced the transformation frequency. These experiments show that the inhibition of transformation by Na2SeO3 is not the result of an antiproliferative effect. They further indicate that the inhibitory effect occurs even when the chemical treatment occurs during the 'postinitiation' phase. Thus the inhibition of transformation by Na2SeO3 cannot solely be explained by its effects on drug metabolism.