The microbiological diagnosis of tuberculosis in areas under strict radiation control

Mycobacterial variability was studied in active tuberculosis patients from radioactive contamination area subject to close radiation control. For such areas it was noted that the patients discharge altered coccoid mycobacteria stained with routine luminescent dyes. Biological investigations of freshly isolated strains revealed potentiation of M. tuberculosis virulence in patients with respiratory tuberculosis. A large number of patients from the contaminated areas against control demonstrated primary resistance to rifampicin and isoniazid.     

The effect of the calcium channel blockers cinnarizine and flunarizine on the duration of hexobarbital-induced sleep i rats

The effect of the calcium channel blockers cinnarizine (20 mg/kg) and flunarizine (10 mg/kg) on hexobarbital sleeping time in rats has been studied. We have found that cinnarizine when applied intraperitoneally once 1 h or 4 h before hexobarbital and repeatedly for 5 days once daily prolongs sleeping time significantly. When cinnarizine has been introduced simultaneously with phenobarbital (60 mg/kg) for 5 days once daily the sleeping time that was expected to be shortened by phenobarbital only has been obtained to return to control values. Flunarizine has not been found to affect sleeping time significantly either alone or in the presence of phenobarbital. Latencies have not been altered by any of both agents.     

The effect of the lectin from Sambucus nigra inflorescences on spontaneous and alkylating agent-induced mutagenesis in mammalian somatic cells

Data on separation of purified galactose-specific lectin as well as its two polypeptide chains from inflorescences of European elder Sambucus nigra are represented. Their molecule quaternary structure after the pattern a2 b2 is suggested. It was shown that purified protein in concentration 2.0 mg/ml had mutagenic activity and might enhance mutagenic effect of alkylating substance MNNG. Thus, preparations of lectin from inflorescences of European elder influenced on spontaneous and induced by the alkylating agent mutagenicity in mammalian somatic cells in vitro.     

Spontaneous and induced mutagenesis in a culture of Chinese hamster cells

Spontaneous and nitrosoguanidine (NG)-induced rate of reversions to glutamine independence was studied in cultured temperature-sensitive glutamine auxotrophs of Chinese hamster cells. In 3 experiments the spontaneous rate of reversions varied from 0.8-10(-6) to 3.84-10(-6) per cell per generation. A dependence of the yield of NG-induced back mutations upon the time interval between the mutagenic treatment and the transfer to selective conditions (glutamine deficient medium, 40 degrees C) was established. No induced revertants were detected when cells were transferred to selective conditions immediately after the treatment with NG. After 2--3 days cultivation in glutamine containing medium at 36 degrees C and the sunsequent transfer to selective conditions the frequency of induced reversions varied from 0.56-10(-4) to 10.55-10(-4) in different experiments; after 6 days -- from 0.05-10(-4) to 4.0-10(-4). In all cases where induction was detected, the difference, between the frequency of glutamine prototrophs in treated and control plates was significant. Glutamine independence proved to be stable after prolonged cultivation under non-selective conditions, the degree of prototrophy being greatly unequal in different clones. No differnce in this respect was detected between spontaneous and NG-induced revertants. The proposed system of reverse mutations can be used for studying diverse problems of somatic cell genetics.     

Essential binding and functional domains of human bleomycin hydrolase

Bleomycin hydrolase (BH) is unusual among cysteine proteinases because it appears to form multihomomeric structures, inactivates the antitumor glycopeptide bleomycin, and contains a unique C-terminal amino acid sequence. We now demonstrate intrinsic endopeptidase activity associated with human BH (hBH) using artificial substrates and intracellular dimerization of hBH using a yeast two-hybrid assay. To determine domains important for homomeric interactions and catalysis, we constructed N- and C-terminal deletion mutants and identified an N-terminal region (hBH1-82) that interacted with two nonoverlaping hBH domains: one near the N-terminus (hBH14-103) and another neighboring the C-terminus (hBH358-455). In vitro hBH aggregated with a molecular mass of 235 kD corresponding to a homotetramer and the C-terminus was critical for this oligomerization since no tetramers were found when the last 40 amino acids were deleted. The penultimate 8 amino acids, which constitute a unique and highly conserved bleomycin hydrolase-like domain (BHYD), were essential for BH and aminopeptidase activity but not for endopeptidase activity or oligomer formation. Thus, the C-terminus of hBH has two independent roles controlling both the catalytic activity and oligomerization of hBH.