Prévalence de l'infection cervicale à Chlamydia trachomatis dans une population féminine consultant pour contraception.

OBJECTIVES: To determine the prevalence and risk indicators of cervical infection due to Chlamydia trachomatis among female patients consulting for contraception and to evaluate an enzyme immunoassay for the detection of C. trachomatis in this setting. DESIGN: Prevalence study. Endocervical specimens were analysed by means of culture and enzyme immunoassay. C. trachomatis infection was diagnosed through culture. SETTING: A hospital family planning clinic in Trois-Rivières, Que. SUBJECTS: All 533 female patients who consulted for contraception between November 1986 and March 1988. Results of culture were available for 495 patients. MAIN OUTCOME MEASURE: Demographic, epidemiologic and clinical information was collected by means of a standard questionnaire and a gynecologic examination. MAIN RESULTS: The prevalence rate of chlamydial infection was 9% (45/495). Enzyme immunoassay detected 37 (82%) of the infections. The mean age of the patients was 19.8 years, and 98% of the infections were diagnosed in those aged 25 years or less. The variables significantly associated with C. trachomatis infection were having more than one sexual partner in the preceding year (odds ratio [OR] 2.9; 95% confidence limits [CL] 1.7 and 5.0) and having more than one partner in the preceding 3 months (OR 2.3; 95% CL 1.2 and 4.3). These two indicators would have detected 58% and 22% of the infections respectively. CONCLUSIONS: Screening for C. trachomatis infection by means of enzyme immunoassay should be proposed to all female patients aged 25 years or less consulting for contraception in our clinic. Such screening may prove to be an effective preventive measure in other similar clinical settings.     

Artifacts arising from sampling interval in dive depth studies of marine endotherms

Most depth recorders used to study the diving behaviour of polar marine endotherms record depth data at specific time intervals. The length of recording interval can have potentially profound implications for the interpretation of the data. We used data acquired on the diving behaviour of king penguins, Aptenodytes patagonicus, to examine the validity of various analyses routinely conducted on depth data. In our experiments, increasing the sampling interval led to an underestimation of the number of dives performed, an overestimation in mean dive duration and substantial changes in the form of the dive profile. Our analysis indicates that depth data should be recorded at a minimum rate corresponding to 10% of the total dive duration and that conventional dive profile categorization may be inappropriate. Alternatives that are less subjective, and based on curve fits of dive depth versus time, are proposed.     

Some characteristics of mitochondrial multienzyme systems from rat liver mitochondria after heating of rats]

A character of rat liver mitochondria degradation after the heat treatment of animals is studied. It is found that mitochondria under the effect of elevated temperature do not considerably change their functional characteristics and thus they are capable to provide the normal rate of ATP synthesis, the rate of succinate oxidation being slightly increased. At the same time the heating caused the degradation of mitochondria which results in the decrease of their thermostability, in the increased susceptibility to lytic effect of trypsin and phospholipase D, and in the activation of succinate dehydrogenase and cytochrome c oxidase. The mitochondria degradation is due to the formation of "latent impairments" in the structure of mitochondria.     

Dictyostelium myosin II heavy-chain kinase A is activated by heparin, DNA and acidic phospholipids and inhibited by polylysine, polyarginine and histones.

Dictyostelium myosin II heavy-chain kinase A (MHCK A) is activated by autophosphorylation. Heparin and DNA, as well as vesicles composed of phosphatidylserine or phosphatidylinositol, were found to increase the initial rate of MHCK A autophosphorylation 5-10-fold in a Ca(2+)-independent manner. The negatively charged molecules also increased the activity of the autophosphorylated MHCK A by about 2-fold. In contrast, positively charged polypeptides such as poly(D-lysine), poly(L-lysine), poly(L-arginine) and histones strongly inhibited (IC50 of 0.5 micrograms/ml) the activity of the active, autophosphorylated MHCK A. Similar levels of inhibition, on a weight basis, were observed for poly(L-lysine) fractions with molecular weights from 3800 to 150,000-300,000. The inhibition was competitive with respect to peptide substrate and mixed with respect to ATP. At much higher concentrations poly(L-lysine) also inhibited the ability of MHCK A to autophosphorylate. It is proposed that negatively charged compounds and autophosphorylation increase the activity of MHCK A by weakening the interaction between the catalytic domain and a positively charged autoinhibitory domain.     

Effect of stobadine on indomethacin- and ethanol-induced stomach lesions and gastric secretion.

Stobadine was found to inhibit the ulcerogenic activity of indomethacin in relation to the dose but was ineffective against the direct necrotizing action of ethanol. It also inhibited gastric acid secretion when administered intraduodenally. Although stobadine is considered to be a scavenger of free radicals, our results indicate that, under the given experimental conditions, it is rather the inhibition of gastric acid secretion that is responsible for its antiulcerogenic effect. The preliminary results do not allow the exclusion of other mechanisms for explaining its antiulcerogenic effect.     

Substrate specificity and adenosine triphosphatase activity of the ATP-dependent deoxyribonuclease of Bacillus subtilis

Studies on the specificity of the ATP-dependent DNase of Bacillus subtilis 168, carried out with pure enzyme at the optimal conditions for its action, have shown that the substrate is double-stranded linear DNA. Linear single-stranded DNA (separated strands of B. subtilis DNA and linear phage fd DNA) is not attacked, neither are there any circular forms (supercoiled or nicked simian virus 40 and circular single-stranded fd DNAs). The double-stranded DNA can be completely hydrolysed, the limit products being, almost exclusively, mononucleotides. The presence of terminal phosphate residues in the substrate (either at the 3' or the 5' end) is not necessary for enzyme action. This DNase appears therefore to be an exonuclease processively liberating mononucleotides from both strands of the native linear DNA. ATP (indispensable for the DNase reaction) is also hydrolysed by the enzyme, to ADP and inorganic orthophosphate (Pi) in the presence of DNA. The apparent Km for ATP, in the ATPase reaction, is 0.15 mM. At high ATP concentrations, which inhibit the DNase activity, there is activation of the ATPase reaction. Three molecules of ATP are consumed for each DNA phosphodiester bond split, at optimal conditions for DNase activity.     

The isolation and properties of a denitrifying bacterium of the genus Flavobacterium

A previously undescribed denitrifying bacterium was isolated from soil. The cells are small gram-negative rods, asporogenous, and non-motile. Colonies become yellow after long exposure to light. This colouring is due to the production of a carotenoid pigment. The organism shows no fermenting activity, and grows only in the presence of one of the following electron acceptors: NO _inf2 ^sup- , N₂O, and O₂. It does not reduce nitrate. It gives a positive oxidase test and has a cytochrome c and catalase. It requires no growth factors, is a chemoorganotroph and uses only sugars as carbon and energy supply. The DNA base composition is 40.8 moles percent GC. Although presenting the physiological characteristics of a pseudomonad, the organism described has been placed in the genus Flavobacterium because of its pigmentation and its low GC percentage.     

Changes in fibrinolysis components during short-term adaptation to high altitude]

In studying hemocoagulation in dogs under conditions of Frunze (760 m above the sea level) and Tuya-Ashu (3200 m above the sea level) it was shown that in the "emergency" phase of adaptation (the first three days) there was seen activation of fibrinolysin and profibrinolysin with depression of antifibrinolysins and inhibitors of profibrinolysin activators. The concentration of plasma fibrinogen at that period decreased by 100 mg%, which could promote an increase in the vascular permeability and improvement of oxygen approach to the tissues. Later, along with elevation of fibrinolysin and profibrinolysin activators there was a marked increase in the level of fibrinolysis inhibitors. Correlation of all the fibrinolysis components was established at a new level.     

Oxidation of methanol,formaldehyde and formic acid by methanol-utilizing yeast

Methanol-utilizing yeast,Candida boidini 11 Bh, characterized by high tolerance to methanol during growth, displays even higher tolerance when the oxidation rate by intact cells is tested. Low respiration activity is found even at 22% v/v of methanol. The half-saturation constant was 17–18mM. The half-saturation constants for the two oxidation intermediates, formaldehyde and formic acid were 3.6–4.0 and 30–33mM, respectively. When applied together with standard concentration of methanol, very low concentrations of both intermediates stimulated the oxidation rate. These results are discussed in connection with the relationship between growth and oxidation, the tolerance to high concentrations of inhibitory products and the mechanism of inhibition.