Antituberculous drug susceptibility testing of Mycobacterium bovis BCG strain Montréal

Testing of Mycobacterium bovis BCG strain Montréal for susceptibility to four primary antituberculous drugs (isoniazid, ethambutol, streptomycin, and rifampin) and to one secondary drug (p-aminosalicylic acid) showed the strain to be susceptible to all five substances. Mycobacterium bovis strains ATCC 35735, which is isoniazid sensitive, and ATCC 35747, which is isoniazid resistant, were included in the test; with the exception of their respective susceptibility to isoniazid, both were inhibited by the other four drugs.     

Transfer ribonucleic acid methylase activity in adult and fœtal rat liver

Foetal rat liver extracts were found to have higher tRNA methylase activities than corresponding extracts of adult liver. When the specific activities were expressed per mg of liver or per mg of protein, the foetal tRNA methylating enzymes were respectively 2.5 and 6 times higher than those of adult livers.The presence of an inhibitor in adult liver can be excluded, since the same recoveries of total tRNA methylase activity were obtained after partial purification of both adult and foetal liver extracts: yields were close to 100 per cent.The apparent Km's for the substrates in the methylating reactions were the same when tRNA methylases from either adult or foetal liver were used: values were 0.2 μM for Escherichia coli tRNA and 2.1 μM for S-adenosyl-l-methionine.After T₁-T₂ ribonuclease digestion of an in vitro methylated tRNA, similar methyl nucleotide patterns were observed in foetal and adult enzymatic extracts.It is concluded that the same tRNA methylase pool is present in adult and foetal liver. In addition, it is hypothesized that the different reaction rates exhibited by these enzymes might be due to the tRNA functional requirements rather than to the presence of a tRNA methylase inhibitor.     

Pharmacologic modulation of RNA splicing enhances anti-tumor immunity

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Cryogenic stabilization of myoglobin photoproducts

The low frequency resonance Raman spectra of photodissociated carbon monoxymyoglobin at cryogenic temperatures (4-77 K) differ from those of deoxymyoglobin. Intensity differences occur in several low frequency porphyrin modes, and intensity and frequency differences occur in the iron-histidine stretching mode. This mode appears at about 225 cm-1 in deoxymyoglobin. At the lowest temperature studied, approximately 4 K, the frequency of the iron-histidine stretching mode in the photoproduct is approximately 233 cm-1, and the intensity is very low. When the temperature of the photoproduct is increased, the intensity of the mode increases, but its frequency is unchanged. The differences between the photoproduct and the deoxy preparation persist to 77 K, the highest temperature studied, and are independent of whether samples are frozen in phosphate buffer or a 50:50 ethylene glycol/phosphate buffer mixture. It is proposed that the frequency of the iron-histidine stretching mode is governed by the tilt angle of the histidine with respect to the normal to the heme plane, and the intensity of the mode is governed by the overlap between the sigma orbital of the iron-histidine bond and the pi orbital of the porphyrin macrocycle. This model can account for differences between the resonance Raman spectra of the photoproduct and the deoxy preparations of both hemoglobin and myoglobin. Furthermore, by considering the F-helix motions in going from 6-coordinate to 5-coordinate hemoglobin and myoglobin, the heme relaxation of these proteins at room temperature with 10-ns pulses can be explained. Based on the findings reported here, low temperature relaxation pathways for both hemoglobin and myoglobin are proposed.     

The light-harvesting antenna of brown algae: highly homologous proteins encoded by a multigene family.

Accessory light-harvesting complexes (LHCFs) were isolated from the brown alga Laminaria saccharina. Complexes specifically associated with photosystem I or II are identical with each other with respect to molecular mass, isoelectric point and behavior on anion-exchange chromatography or non-denaturing isoelectric focusing. The purified complexes also have similar pigment composition and spectroscopic properties. It is concluded that LHC antennae associated with photosystem I or II cannot be distinguished biochemically. After screening of genomic and cDNA libraries produced from L. saccharina sporophytes, six lhcf genes were isolated. Sequence analysis of these lhcf genes showed a high level of homology between the encoded polypeptides. Comparisons with coding sequences of lhcf genes from Macrocystis pyrifera and expressed sequence tags from Laminaria digitata (two other Laminariales) indicated that these proteins are probably very similar in all brown algae. Another feature common to the lhcf genes characterized was the presence of an intron in the coding region corresponding to the plastid-targeting presequence. The sequence similarity extended to the 5' and 3' UTRs of several genes. In spite of the common origin of the chloroplasts, no light-regulating elements involved in the expression of the genes encoding the higher-plant light-harvesting proteins has been found in the UTRs.     

A feasibility study into adenosine triphosphate measurement in exhaled breath condensate: a potential bedside method to monitor alveolar deformation

Recent research suggested an important role for pulmonary extracellular adenosine triphosphate (ATP) in the development of ventilation-induced lung injury. This injury is induced by mechanical deformation of alveolar epithelial cells, which in turn release ATP to the extracellular space. Measuring extracellular ATP in exhaled breath condensate (EBC) may be a non-invasive biomarker for alveolar deformation. Here, we study the feasibility of bedside ATP measurement in EBC. We measured ATP levels in EBC in ten subjects before and after an exercise test, which increases respiratory parameters and alveolar deformation. EBC lactate concentrations were measured as a dilution marker. We found a significant increase in ATP levels in EBC (before 73 RLU [IQR 50–209] versus after 112 RLU [IQR 86–203]; p value 0.047), and the EBC ATP-to-EBC lactate ratio increased as well (p value 0.037). We present evidence that bedside measurement of ATP in EBC is feasible and that ATP levels in EBC increase after exercise. Future research should measure ATP levels in EBC during mechanical ventilation as a potential biomarker for alveolar deformation.