Vasodilation with adenosine or sodium nitroprusside after coronary artery bypass surgery: a comparative study on myocardial blood flow and metabolism

The effects of adenosine and sodium nitroprusside (SNP) on central hemodynamics and myocardial blood flow and metabolism were investigated postoperatively after elective coronary artery bypass (CABG) surgery in ten sedated and mechanically ventilated patients in the intensive care unit. During three consecutive 15-min periods, SNP (0.8 +/- 0.1 micrograms.kg-1 x min-1), adenosine (88.9 +/- 13.3 micrograms.kg-1 x min-1), and then again SNP (0.7 +/- 0.1 micrograms.kg-1 x min-1) were infused to control postoperative hypertension at a mean arterial pressure of approximately 80 mm Hg. Systemic and pulmonary hemodynamics and global (coronary sinus flow, CSF) as well as regional (great cardiac vein flow, GCVF) myocardial blood flow and metabolic variables were measured. During adenosine infusion, in comparison to SNP, heart rate was unchanged, stroke volume index and cardiac index increased (24% and 32%, respectively), and the systemic vascular resistance index decreased (-26%). Mean pulmonary arterial pressure (24%) as well as pulmonary capillary wedge pressure (27%) and central venous pressure (18%) were higher with adenosine compared to SNP. Adenosine also increased CSF and GCVF (108% and 103%, respectively) without altering the CSF/GCVF flow ratio compared to SNP. Furthermore, adenosine increased the coronary oxygen content (51%) and decreased the arterio-great cardiac vein oxygen content difference (-48%) without changing regional myocardial oxygen consumption, indicating a more pronounced hyperkinetic myocardial circulation compared to SNP. In addition, adenosine infusion decreased arterial PO2 (-11%) and increased the intrapulmonary shunt fraction (57%). The PR interval time of the electrocardiogram was prolonged (12%) and the ST segment was more depressed during adenosine infusion compared to SNP.(ABSTRACT TRUNCATED AT 250 WORDS)     

Potentiation of tumour necrosis factor-mediated cell killing by VP16 on human ovarian cancer cell lines. In vitro results and clinical implications

Synergism between recombinant human tumour necrosis factor (rHuTNF) and DNA topoisomerase II inhibitor VP16 during the killing of cells has been studied in six human ovarian cancer cell lines (A2774, A2780, SW626, IGROV-1, SKOV3, Pa1) and a cervical carcinoma cell line (Me180). Studies were performed using an assay of colony formation inhibition (drug treatment for 1 h) and a growth inhibition assay (continuous exposure for 20 h). Concomitant treatment of cells with VP16+rHuTNF enhanced cell killing in all the cell lines tested--an effect observed in both short- and long-term cytotoxicity assays. This study suggests that the activity of VP16 in ovarian cancer cell lines might be enhanced by rHuTNF in in vitro models.     

Cell density-dependent DNA fragmentation and its suppression by heparin in primary culture of adult rat hepatocytes

We show here that the internucleosomal DNA fragmentation, which is a biochemical hallmark of apoptosis, was induced in a cell density-dependent manner in primary culture of adult rat hepatocytes. This DNA fragmentation could be suppressed by a gene expression inhibitor, indicating the active nature of this process. Moreover, the viability changes in high and low cell density cultures showed a tendency corresponding with the incidence of the DNA fragmentation in them. These results suggest that in hepatocytes there may be a cell density-dependent apoptosis mechanism. In this report, we also show that heparin could suppress this DNA fragmentation with high specificity, and the cell death to some extent.     

A study of phase equilibria of nitrogen for constructing a medium value pressure scale

Translated from Izmeritel'naya Tekhnika, No. 3, pp. 40–42, March, 1993.     

Processing and microstructure of non-oxide ceramic fibres

Research and development efforts on high-temperature, oxidation-resistant fibres have increased over the past decade due to the demand for light-weight, stiff and strong composite materials in aerospace applications. Varieties of ‘high-performance’, continuous, non-oxide fibres with low-density, high tensile strength and tensile modulus have been developed either from organic precursors or via chemical vapour deposition for fabrication of ceramic matrix composites. Fibres derived from polymer precursors (e.g. Nicalon, Tyranno, HPZ) are small in diameter (compared to CVD monofilaments) and are ideally suited for ceramic composites. Processing, microstructural stability and mechanical properties of these newly developed SiC and Si₃N₄ base fibres are briefly reviewed in this paper.     

Difference between human and guinea pig Hageman factors in activation by bacterial proteinases: cleavage site shift due to local amino acid substitutions may determine the activation efficiency of serine proteinase zymogens

Human and guinea pig Hageman factors have been subjected to the action of pseudomonal elastase and serratial E15 proteinase. The pseudomonal elastase cleaved 22-24% of the human molecule at Arg353-Val354, and the remainder at Gly357-Leu358 resulting in the generation of about 20% of potential activity as activated Hageman factor, compared with trypsin activation, while it hydrolyzed Arg340-Ile341 bond in guinea pig molecule and generated about 75% of activity as activated Hageman factor. The serratial proteinase did not hydrolyze the essential cleavage site (Arg353-Val354) of the human zymogen but Gly356-Gly357 (30%) and Gly357-Leu358 (70%) bonds. Both products showed no activity. The guinea pig zymogen, in contrast, was cleaved mostly at Arg340-Ile341 (70%) and less abundantly at Gly344-Leu345 (30%), generating about 85% of the whole potential activity as activated Hageman factor. From the high correspondence between the proportions of activation and of hydrolysis at the essential cleavage site in activation, it was concluded that hydrolysis of the bonds different from the essential bond did not cause activation, even when the spatial separation was only 3 or 4 residues. Considering the amino acid differences between human and guinea pig Hageman factors, -Met351-Thr-Arg-Val-Val-Gly-Gly-Leu-Val-Ala360- and -Leu338-Ser-Arg-Ile-Val-Gly-Gly-Leu-Val-Ala347-, respectively, it was realized that even the minor amino acid substitutions caused the cleavage site shift which resulted in significant differences in activation efficiency of the proteinase zymogens.     

Changes of the combustion regimes of nongasifying and low-gas systems over the parameter range

The process of combustion of homogeneous and heterogeneous nongasifying and slightly gasifying systems over the range of a number of parameters characterizing the reactive composition and the conditions for the arrangement of the combustion process is studied by using thermocouple and optical methods. The regions of the implementation of different combustion regimes, namely, steady, pulsating, multiple-point, and spin, are determined experimentally.Institute of Structural Macrokinetics, Russian Academy of Sciences, Chernogolovka. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 65, No. 4, pp. 407–411, October, 1993.     

Some features of the chemical transformation of a highly exothermic ore concentrate-based mixture in a combustion wave

Use of inexpensive ore concentrates as initial components in SHS metallurgy [1–3] brings about some specific features in the process and the properties of the materials obtained. Ore reagents contain a considerable amount of impurities (Al₂O₃, SiO₂, Fe₂O₃) that decrease the energetics of SHS systems and the temperature and the rate of combustion and create the limits of combustion and phase separation. In addition, the impurities participate in chemical reactions and enter the desired product. In many cases the presence of silicon, iron, and aluminum in a cast product does not prevent use of this product for practical purposes.Institute of Metallurgy, Academy of Sciences of the Republic of Georgia, Tbilisi. Institute of Structural Macrokinetics, Russian Academy of Sciences, Chernogolovka. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 65, No. 5, pp. 613–616, November, 1993.     

Modified hippocampal long-term potentiation in PKC gamma-mutant mice

Calcium-phospholipid-dependent protein kinase (PKC) has long been suggested to play an important role in modulating synaptic efficacy. We have created a strain of mice that lacks the gamma subtype of PKC to evaluate the significance of this brain-specific PKC isozyme in synaptic plasticity. Mutant mice are viable, develop normally, and have synaptic transmission that is indistinguishable from wild-type mice. Long-term potentiation (LTP), however, is greatly diminished in mutant animals, while two other forms of synaptic plasticity, long-term depression and paired-pulse facilitation, are normal. Surprisingly, when tetanus to evoke LTP was preceded by a low frequency stimulation, mutant animals displayed apparently normal LTP. We propose that PKC gamma is not part of the molecular machinery that produces LTP but is a key regulatory component.