Optimization of collimation system parameters of radioisotope tomograph]

An index of completion of phagocytosis was studied for staphylococcus cultures of various biological activity in experiments with surviving polymorphonuclear leukocytes. Among the coagulase-forming staphylococci virulent strains proved to be nonviable in a lesser percentage of cases than the avirulent ones. Coagulase- and mannite-negative cultures proved to be most unstable. Staphylococcus toxin depressed the migration of polymorphonuclear leukocytes to the focus of irritation, inhibited ingestion of the virulent, and, to a lesser degree, of avirulent coagulase-forming staphylococci, but failed to influence the ingestion of coagulase-negative epidermal staphylococci. The influence of staphylotoxin on the phagocytosis completion index was either the minimal or absent entirely.     

Prevention of balloon damage during initiation of intra-aortic balloon counterpulsation

Damage to an intra-aortic balloon occurred on two occasions in 93 insertion procedures. The complication was recognized before gas embolization occurred, and neither patient suffered ill effects. On both occasions the balloon was holed when pinched by artery forceps applied to the 'dacron' graft.     

Quantitative aspects of the formation of a half chromatid chiasma as an intermediate product of genetic recombination in bacteriophages

Formal genetic consequences of generation and break-up of a half chromatid chiasma have been studied on the basis of a model with the symmetric exchange of two strands between parental DNA molecules. In recombination analysis, generation and break-up of this structure gives rise to a critical frequency R (zeta), which corresponds to recombination between two markers separated by a distance equal to the mean genetic length zeta of the hybrid region at the time of scission of the cross connection. The use of the distance zata as a natural unit of a genetic map is suggested. In the case of bacteriophage T4 under conditions of standard crosses the half chromatid chiasma is characterized by the value R (zata) equal to 3.0-10(-2), the structure acquiring with equal probability either of the two alternative isomeric configurations at the time of scission of the cross connection. About four per cent of the total number of mismatches as a result of break-up to the half chromatid chiasm were repaired.     

Cloning and expression of a plasmid pBS195 gene, determining oxygenase activity, in Escherichia coli cells

Plasmid pBS195, detected in a strain of Lactobacillus sp. isolated from long-living persons, has a broad host range, including Gram-positive and Gram-negative microorganisms [1]. Plasmid-harboring colonies of the strain Escherichia coli HB101 give a color reaction with catechol. This indicates that genes mediating the activity of oxygenase are present in this plasmid. The high activity level of this enzyme, mediated by pBS195, and substrate specificity, which has not bee detected in any known metapyrocatechases, were found in cells of E. coli. Hybridization with a 32P-labeled fragment containing the NahC gene revealed a region of homology with a 1.6-kb EcoR I- BamH I fragment of plasmid pBS195. Deletion variants of this plasmid that lost oxygenase activity confirmed the location of the oxygenase gene in this region. The gene responsible for oxygenase activity in the plasmid was cloned on the pUC19 vector in E. coli cells. The expression of the cloned gene is controlled by the lac promoter of this vector. Physical, hybridization, and deletion analyses as well as analysis of polypeptides, which are synthesized in E. coli mini-cells, showed that this activity requires the participation of a polypeptide with molecular mass of 34 kDa.     

Role of p53 in the regulation of irradiation-induced apoptosis in neuroblastoma cells

Myocardial texture analysis of two-dimensional echocardiographic gray level distribution is abnormal in hypertensive patients with severe increase of left ventricular mass. The aim of this study was to investigate the behavior of this parameter in hypertensive patients with absent-to-moderate left ventricular hypertrophy, more representative of the overall hypertensive population. We compared male essential hypertensive patients, with absent or mild-to-moderate left ventricular hypertrophy, with normotensive sedentary healthy subjects as controls. The groups (n = 18 each) were age- (+/- 2 years) and sex-matched. All subjects performed ambulatory blood pressure measurements for the evaluation of 24 h mean systolic and diastolic blood pressure. Quantitative analysis of echocardiographic digitized imaging was performed through a calibrated 256 gray level digitization system to calculate midseptum and midposterior end-diastolic and end-systolic first and second order textural analysis. In particular were observed the mean gray level cyclic variations to deriving the cyclic variation index (CVI). The hypertensives showed a significantly lower CVI compared with controls both for septum (P < .001) and for posterior wall (P < .0001). No significant relationships were found between CVI and relative diastolic thickness both of septum and posterior wall. Conversely, a significant inverse relationship was found between systolic arterial pressure values and CVI both of septum and posterior wall. Abnormalities of two dimensional echocardiographic gray level distribution are present also in hypertensive patients with absent or with mild-to-moderate levels of left ventricular hypertrophy, but seem unrelated to the degree of echocardiographic hypertrophy as such. Changes in collagen network distribution or microcirculatory alterations, secondary to pressure-volume overload per se or to other complex humoral factors, could explain these abnormalities. Further work is needed to establish the clinical, therapeutic, and prognostic implications of these findings.