Structure of silicon carbide powders produced in interaction of silica with carbon black

Translated from Poroshkovaya Metallurgiya, No. 7(355), pp. 47–52, July, 1992.     

Utilization of fine-needle aspiration cytology and flow cytometry in the diagnosis and subclassification of primary and recurrent lymphoma

The aim of this study was to assess and compare spinal cord injured (SCI) and traumatic brain injured (TBI) persons and people from the general population concerning partner relationships, functioning, mood and global quality of life. One hundred and sixty seven SCI persons, 92 TBI persons and 264 controls participated in the study. The median age was: SCI persons 33 years (range 19 to 79 years), TBI persons 40 years (range 20 to 70 years), and controls 31 years (range 19 to 79 years). Age at injury ranged among SCI persons from 14 to 76 years (Md 28 years), and among TBI persons from 16 to 56 years (Md 32 years). Half of the SCI group (51%), 58% of the TBI group and 59% of the controls had a stable partner relationship at the time of the investigation. Many of these SCI and TBI relationships (38% and 55% respectively) were established after injury. Both SCI and TBI persons showed significantly more depressive feelings compared with the controls. Perceived quality of life (global QL rating) was significantly lower in the SCI group compared with the controls, whereas the ratings of TBI persons and controls did not differ significantly. SCI and TBI persons did not differ significantly in level of education, perceived quality of life or distress. In all three groups, global quality-of-life ratings were significantly lower among single persons compared to those with a partner relationship. It was concluded that both SCI and TBI appear to affect overall quality of life and mental well-being negatively. The number of partner relationships contracted after injury among both SCI and TBI persons indicates, however, that the injury is not a major barrier to establishing close partner relationships. Being in good spirits, that is, lack of depressive feelings has a profound impact on the perception of a high quality of life in all three groups. For the SCI and TBI persons, a high level of physical and social independence were further positive determinants of a perceived high quality of life.     

Effect of heart failure on muscle capillary geometry: implications for 02 exchange

There is strong evidence that chronic heart chronic heart failure (CHF) impairs skeletal muscle function independent of blood flow and bulk O2 delivery. Purpose: This investigation sought to determine whether alterations in muscle capillary geometry and surface area that are thought to be primary determinants of the efficacy for blood-tissue 02 exchange might be altered in CHF and contribute to these changes. Methods: Plantaris (fast twitch) and soleus (slow twitch) muscles from control (C) and 6- to 7-wk post myocardial infarcted (CHF) rates were perfusion-fixed in situ. These muscles were analyzed using morphometric techniques that facilitated determination of muscle sarcomere length fiber cross-sectional area, capillary tortuosity and branching coefficient (c(K,0)), capillary length, volume, and surface area. Results: Normalized to a sarcomere length of 2.1 microns, plantaris fiber cross-sectional area decreased by 21% (P < 0.05), and capillary-to-fiber ratio decreased from 2.05 +2- 0.07 in C to 1.79 +2- 0.04 (P < 0.05) in CHF, but these variables were unchanged in soleus. These was no change in c(K,0) or capillary diameter in either muscle, and thus capillary length and surface area per fiber volume remained unchanged. From the measured fiber atrophy and capillary involution in plantaris reductions of total muscle capillary length, volume, and surface area of 11%, 9% and 17%, respectively, are estimated. Conclusion: These changes, coupled with reduced blood flow may impair the effective matching of muscle fiber 02 delivery to 02 requirement during repeated muscle contractions (i.e. exercise). The scenario is expected to reduce intramyocyte 02 partial pressure and thereby contribute to the greater fatigability characteristic of the CHF condition.     

Sensitivity of B- and C-DNA forms to modifications by O-methylhydroxylamine

Effects of high concentrations of lithium, cesium and ammonium chlorides on the reaction ability of free CMP and cytosine in free DNA of CD phage with respect to O-methylhydroxylamine (OMHA) are studied. CMP reaction in all the cases takes place mainly for 24 hours. Like classical B-form, native DNA, having C-form in high ionic strength solution (as estimated from circular dichroism data), is not modificated. Thus, the access of some cytosine residues in intraphage DNA to OMHA is due not to the decreased DNA hydratation in situ, but to the presence of differently ordered regions in DNA.     

Regulation of growth of human diploid fibroblasts by factors elaborated by activated lymphoid cells

Fibroblasts growth synthesis activities appear to be under exquisite control. This control is mediated in part by substances present in blood plasma or released by other cells. We have studied the role of peripheral blood mononuclear cells (PBM) activated with phytohemagglutinin-P (PHA) on DNA synthesis, proliferation, and the cell cycle of human diploid fibroblasts. Culture medium from activated but not from unactivated PBM cultures inhibited fibroblast DNA synthesis and growth in a dose-dependent manner. The activity, which was designated as lymphocyte factor (LF), was very potent; it inhibited 50% of the DNA synthesis and cell growth at a dilution of 1:160. It has a molecular weight between 50,000 and 100,000 daltons and it is destroyed by trypsin digestion or by heating at 80 degrees C for 30 minutes. The activity was not due to the presence of prostaglandin. Furthermore, using immunoprecipitation and affinity chromatography, it was shown conclusively to to be distinctly different from alpha lymphotoxin (alpha-LT). It was not cytotoxic, as shown by the 51chromium release technique. Using flow microfluorimetry it was shown that the activity regulates fibroblast growth by preventing quiescent cells in the G0 or G1 stage of the cell cycle from entering the S phase. Cells already in S at the time of exposure complete DNA synthesis but cannot divide, and they accumulate in G2. The activity also has marked effects on protein synthesis. Activated mononuclear cells may play a major role in regulating fibroblast growth and synthesis in normally healing wounds and in acute and chronic inflammatory processes.     

Change in the metabolism and toxic effect of benz(a)pyrene by its metabolites and a series of phenols

Effects of some phenols and polycyclic aromatic hydrocarbon derivatives on benz(a)-pyrene metabolism have been studied in the microsomal system isolated from the mouse embryonic cell cultures. The rate of benz(a)pyrene metabolism was shown to depend on the structure and concentration of the agents added. The toxic effect of benz(a)pyrene was summed up with that of either agent studied (except ionol) added simultaneously to the cell culture.