Interaction of RecBCD enzyme with DNA at double-strand breaks produced in UV-irradiated Escherichia coli: requirement for DNA end processing

The RecBCD enzyme has a powerful duplex DNA exonuclease activity in vivo. We found that this activity decreased strongly when cells were irradiated with UV light (135 J/m2). The activity decrease was seen by an increase in survival of phage T4 2(-) of about 200-fold (phage T4 2(-) has defective duplex DNA end-protecting gene 2 protein). The activity decrease depended on excision repair proficiency of the cells and a postirradiation incubation. During this time, chromosome fragmentation occurred as demonstrated by pulsed-field gel electrophoresis. In accord with previous observations, it was concluded that the RecBCD enzyme is silenced during interaction with duplex DNA fragments containing Chi nucleotide sequences. The silencing was suppressed by induction or permanent derepression of the SOS system or by the overproduction of single-strand DNA binding protein (from a plasmid with ssb+) which is known to inhibit degradation of chromosomal DNA by cellular DNases. Further, mutations in xonA, recJ, and sbcCD, particularly in the recJ sbcCD and xonA recJ sbcCD combinations, impeded RecBCD silencing. The findings suggest that the DNA fragments had single-stranded tails of a length which prevents loading of RecBCD. It is concluded that in wild-type cells the tails are effectively removed by single-strand-specific DNases including exonuclease I, RecJ DNase, and SbcCD DNase. By this, tailed DNA ends are processed to entry sites for RecBCD. It is proposed that end blunting functions to direct DNA ends into the RecABCD pathway. This pathway specifically activates Chi-containing regions for recombination and recombinational repair.     

Histochemical detection of lymphatic drainage pathways in the middle nasal meatus

AIM: Assessment of the antihypertensive effect of doxazosin, alpha-1 blocker, as well as its action on lipid and carbohydrate metabolism, microcirculation and platelet function in patients with non-insulin-dependent diabetes mellitus (NIDDM). MATERIALS AND METHODS: Doxazosin (tonocardin) treatment was given for 11 weeks to 33 NIDDM patients with concomitant hypertension. The clinical examination comprised evaluation of central hemodynamics, vessels of the fundus of eye, lipid and carbohydrate metabolism, renal function, platelet aggregation. RESULTS: Tonocardin produced a fall in the systolic blood pressure (BP) by 14%, in the diastolic BP--by 17%. The 24-h profile of BP, lipid and purine metabolism, microcirculation of the vessels of the fundus of eye also improved. Total peripheral vascular resistance, left ventricular myocardial mass and platelet aggregation. Carbohydrate metabolism remained unchanged. CONCLUSION: Monotherapy with tonocardin (2-8 mg/day) is effective and safe in the treatment of arterial hypertension in NIDDM patients.     

Clonal composition of malignant fibrous histiocytoma: analysis by PCR-based assay of the human androgen receptor gene (HUMARA)

Poly(A)+ mRNA was isolated from leaves of potato plants (Solanum tuberosum L. cv. Desiree) according to standard protocols. This poly(A)+ mRNA was injected via glass microcapillaries into oocytes that were surgically removed from the African clawed toad Xenopus laevis. As a control, oocytes were either injected with H2O or remained untreated. Three days after injection the oocytes were analyzed by two electrode voltage clamping. Current voltage analysis revealed that a K+ channel from potato was functionally expressed in injected oocytes. The identity of this K+ channel was confirmed by its substrate specificity and a shift in the reversal potential. In particular, when the outside K+ concentration was increased the reversal potential of poly(A)+ injected oocytes shifted to more positive values. Furthermore, K+ outward currents declined when the outside K+ concentration was raised from 0.1 to 100 mM. Inward currents increased with an elevation of the K+ concentration. Several pharmaceuticals were tested for their potential to block this K+ channel. As a result, the channel was completely blocked by BaCl2. A three state reaction kinetic model was used to simulate the currents through the K+ transport protein as function of the extracellular K+ concentration. In particular, the simulation revealed current voltage relations that exactly matched the measured ones. Saturation of current voltage curves emerged from the simulation as a consequence of high extracellular potassium concentration.     

Sex pheromone of the oleander scale, Aspidiotus nerii: structural characterization and absolute configuration of an unusual functionalized cyclobutane

The sex pheromone emitted by the female oleander scale, Aspidiotus nerii (Homoptera, Diaspididae), has been isolated and characterized as (1R, 2S)-cis-2-isopropenyl-1-(4'-methyl-4'-penten-1'-yl)cyclobutaneethanol acetate by using advanced MS and NMR spectroscopic methods, as well as a variety of microderivatization sequences. The structure has been confirmed by stereo- and enantioselective synthesis of the four possible stereoisomers. The absolute configuration has been determined by comparison of the activity of the cis (1S,2R) and (1R, 2S) enantiomers with that exhibited by the natural material in greenhouse bioassays and field tests. The structure of this sesquiterpenoid pheromone is new in the coccids and in the pheromone field in general.     

Doppler ultrasound determination of average blood flow velocity and flow volume in transjugular intrahepatic portosystemic shunt (TIPS)

We evaluated the acute and chronic experimental toxicity of a water extract of saponins from Argania spinosa following oral and intraperitoneal (i.p.) administration in mice (Iops Ofa) and rats (Wistar). The DL50 obtained were 79 mg/kg for the i.p. route and 1,300 mg/kg for the oral route. For the chronic toxicity studies, we administred 100 and 200 mg/kg orally once a day during a 3 month period. There was a decrease in blood sugar in the third month of each therapy. Blood creatinine levels increased, thus evoking a renal pathology. A slight increase in transaminases levels was not significatif. Hematologic parameters were unchanged during the treatment and the histopathologic study showed hepatic glycogen decrease and a focal renal tube deterioration.     

Asking for the indicator function of bioassays evaluating soil contamination: are bioassay results reasonable surrogates of effects on soil microflora?

In evaluating the biological effect of solid materials like soil a bacterial contact assay often shows higher sensitivity than elutriate testing. Results of the Bacillus cereus contact assay for some environmental important toxicants are presented in this article. A comparison with another heterotrophic soil bacterium, Arthrobacter globiformis, shows comparable sensitivity. In a bioassay approach organisms at the level of individuals or populations are exposed to soil material to determine the significance of contaminants. An investigation that incorporates community level processes in comparison with toxicity test results provides a better understanding of the indicator function of bioassays. Comparison of soil bioassays (aqueous and solid phase) with ecological parameters demonstrates the problems in predicting ecological effects of soil contamination.     

Using neural networks to select wavelet features for breast cancerdiagnosis

This study focuses on improving microcalcification classification by establishing an efficient computer-aided diagnosis system that extracts Daubechies-4 and biorthogonal wavelet features. These wavelets were chosen because they have been used in military target recognition and fingerprint recognition research with images characterized by low contrast, similar to mammography. Feature selection techniques are employed to further increase classification performance. The artificial neural network feature selection techniques are complemented by a conventional decision boundary-based feature selection method. The results using the wavelet features are compared to more conventional measures of image texture, angular second moment, and Karhunen Loeve coefficients. The use of alternative signal processing to compare wavelet and neural techniques allows for a measure of the problem difficulty. It is concluded that advances and contributions have been made with the introduction of two novel feature extraction methods for breast cancer diagnosis, wavelets and eigenmasses. Additionally, feature selection techniques are demonstrated, compared, and validated, transforming adequate discrimination power into promising classification results