Studies on the mechanical resistance of human erythrocytes under in-vitro conditions

Hemolysis and resistance of erythrocytes were studies in-vitro in experiments on human ACD fresh blood and on heparinized fresh blood after oxygen dispersion, resp. mixed oxygen and carbon dioxide dispersion, and subsequent treatment in the hemoresistometer. Blood alkalinity increases under oxygen dispersion, acidity increases under dispersion with mixed gases. The length of the period of dispersion is more important for hemolysis than the change of pH. The hematocrit value influences the behavior of blood resistance. High values imply enhanced hemolysis. There is no significant difference of actual hemolysis values between oxygen and oxygen/carbon dioxide dispersion. A different behavior appears in the calculation of difference value of hemolysis after treatment in resistometer and the respective actual hemolysis.     

High efficiency gene transfer to human hematopoietic SCID-repopulating cells under serum-free conditions

Stable gene transfer to human pluripotent hematopoietic stem cells (PHSCs) is an attractive strategy for the curative treatment of many genetic hematologic disorders. In clinical trials, the levels of gene transfer to this cell population have generally been low, reflecting deficiencies in both the vector systems and transduction conditions. In this study, we have used a pseudotyped murine retroviral vector to transduce human CD34(+) cells purified from bone marrow (BM) and umbilical cord blood (CB) under optimized conditions. After transduction, 71% to 97% of the hematopoietic cells were found to express a low-affinity nerve growth factor receptor (LNGFR) marker gene. Six weeks after transplantation into immunodeficient NOD/LtSz-scid/scid (NOD/SCID) mice, LNGFR expression was detected in 6% to 57% of CD45(+) cells in eight of nine engrafted animals. Moreover, proviral DNA was detected in 8.3% to 45% of secondary colonies derived from BM cells of engrafted NOD/SCID mice. Our data show consistent transduction of SCID-repopulating cells (SRCs) and suggest that the efficiency of gene transfer to human hematopoietic repopulating cells can be improved using existing retroviral vector systems and carefully optimized transduction conditions.     

Percent free prostate-specific antigen in assessing the probability of prostate cancer under optimal analytical conditions

Although general consensus exists that percent free prostate-specific antigen (PSA) is superior to total immunoreactive PSA for prostate cancer (CaP) detection, its diagnostic performance is not yet well established. Analytical problems may account for difficulties in evaluating percent free PSA because the free PSA concentration is substantially lower than that of total PSA. The aim of the present study was to establish the diagnostic performances of the IMMULITE percent free PSA assay from Diagnostics Products Corp. under experimental conditions optimized to minimize analytical variability. Eighty-five patients with untreated primary CaP and 261 with untreated benign prostate hypertrophy (BPH) were prospectively enrolled. The Diagnostics Products IMMULITE total (Third Generation) and free PSA were measured by the same technician, using the same instrument and the same reagent batch. We calculated the post-test probability to express how the likelihood of the diagnosis of CaP changed after the percent free PSA was determined. Areas under the ROC curves of percent free PSA were better than those of total PSA in every evaluated range of total PSA. The percent free PSA could have reduced the rate of unnecessary biopsies by 47% in patients with total PSA >/=4 microg/L with only 3.8% false-negative results. The post-test probability of percent free PSA was, however, <50% in men 50-70 years of age, using cutoff points providing sensitivity from 99% to 80%. Percent free PSA is superior to total PSA in distinguishing primary CaP from BPH in patients with total PSA between 2 and 30 microg/L. In men with low total PSA, the diagnostic performance of the percent free PSA assay may be optimized by controlling methodological variability. The percent free PSA assay is effective in reducing the rate of unnecessary biopsies in men with total PSA >4 microg/L. However, the post-test probability provided by percent free PSA is relatively low in asymptomatic patients 50-70 years of age.     

Some characteristics of the cold densification of wurtzite boron nitride powders under conditions of high pressures

Conclusions Determinations were made, using mercury porosimetry methods, of the specific surfaces and mean particle sizes of the main fractions of wurtzite boron nitride powders and compacts. It was found that in pressing in the pressure range 1.0–10.0 GPa densification was accompanied by intense comminution of BN_w particles. The re-pressing of BN_w powders granulated after being pressed under a pressure of 4.3 GPa was satisfactorily described by M. Yu. Bal'shin's equation.Translated from Poroshkovaya Metallurgiya, No. 10(238), pp. 6–10, October, 1982.     

Phase composition and mechanical properties of cerium- and yttrium-containing Al-Mg alloys subjected to heat treatments under various conditions

The phase composition and properties of Al-Mg-Ce and Al-Mg-Y alloys are studied by optical microscopy and mechanical-property measurements. Isothermal sections at 430 and 275°C that correspond to alloys having manganese concentrations of up to 16% and cerium and yttrium concentrations of up to 0.7% are constructed. The ultimate strength, yield strength, and relative elongation of quenched, worked, and aged Al-Mg-based alloys having 7.0–9.9% Mg and Ce, Y, Mn, and Zr additions are determined. The alloys are aged at 175, 200, 250, and 300°C; the time of aging corresponds to the maximum strengthening effect.     

Studies on the survival of Ascaris suum eggs under laboratory and simulated field conditions

Hypovolemia has been associated with the induction of nitric oxide synthase which is believed to result in an over-production of nitric oxide. In the present study, we have examined the effects of noradrenaline following haemorrhage on cardiac output, blood pressure, mean circulatory filling pressure and vascular resistance in anaesthetized rats after pre-treatment with nitric oxide synthase inhibitor, L-N6-(1-iminoethyl)lysine or dexamethasone. Hypovolemic haemorrhage resulted in induction of nitric oxide synthase, as measured in lungs, and both dexamethasone and L-N6-(1-iminoethyl)lysine inhibited the activity of the inducible form of nitric oxide synthase. An infusion of noradrenaline significantly increased cardiac output, blood pressure and mean circulatory filling pressure in animals pre-treated with L-N6-(1-iminoethyl)lysine and dexamethasone when compared with saline pre-treatment. In addition, the administration of noradrenaline significantly reduced venous resistance in animals pre-treated with L-N6-(1-iminoethyl)lysine when compared with saline pre-treatment. The results of this investigation indicated that the impact of noradrenaline on cardiac output, blood pressure and mean circulatory filling pressure was greater in hypovolemic rats treated with L-N6-(1-iminoethyl)lysine or dexamethasone. In addition, we found that in the hypovolemic state, the greater increase in cardiac output during the infusion of noradrenaline after inhibition of nitric oxide synthase was predominantly due to reduced resistance to venous return.     

Antioxidant enzyme regulation and resistance to oxidants of human bronchial epithelial cells cultured under hyperoxic conditions

OBJECTIVE: The measurement of total serum testosterone has an established clinical role in the management of male hypogonadism and female androgen excess disorders. We studied the between-kit variability and precision of six different commercially available testosterone assays and compared them with an established in-house method. DESIGN: Laboratory observational prospective study. SETTING: Tertiary university medical center clinical laboratory. PATIENT(S): Three groups of samples each of men (n = 36) and women (n = 15) who had high, normal, or low levels of sex hormone-binding globulin (SHBG), respectively, were studied. INTERVENTION(S): Individual and pooled (male and female) serum samples were analyzed for total testosterone concentration using six different commercially available assays and one in-house method. MAIN OUTCOME MEASURE(S): The between-kit variability and the effect of the mean (+/- SD) SHBG level were determined, the results obtained with the use of the kits and the in-house method were compared, and the intraassay variability (i.e., precision) was evaluated. RESULT(S): Male samples demonstrated a 26.3%-40.8% variance in the results obtained with different kits, which was greatest for samples with the lowest SHBG levels. For female samples, between-kit variability ranged from 57%-115% (average, 77%). The percent deviation of the results obtained with the use of commercial methods from those obtained with the use of our in-house assay was greater for men (mean variance, 194%) than for women (mean variance, 67%). The female pool intraassay coefficient of variation was 3.8% with the use of the in-house method and ranged from 8.9%-21.2% with the use of the commercial kits. The male pool intraassay coefficient of variation was 3.1% with the use of the in-house method and ranged from 3.3%-5.5% with the use of the commercial kits. CONCLUSION(S): Most commercially available kits for measuring the total serum testosterone level demonstrated significant between-kit variability, which was greatest for female samples. Further, samples with the lowest SHBG levels had the highest between-kit variances. These data strongly suggest that the measurement of total serum testosterone using commercial kits may have limited utility, particularly for the detection of hyperandrogenemia.     

Effect of heat treatment and microalloying on the cold shortness of steels designed for north

The factors that cause brittle fracture of equipment and constructions made of carbon steels and operating under north conditions in Russia are analyzed. Brittle fracture is shown to be caused by the region in the heat-affected zone of a welded joint where strain aging takes place in welding. Regression equations that describe the relationships between the yield strength of steel and the ductile-brittle transition temperature, on the one hand, and the grain size, on the other, are calculated. The fracture surfaces of steel samples before and after strain aging are studied. The effect of microalloying with vanadium or niobium on the cold shortness of carbon steels is analyzed.     

Parasitic systems under the conditions of human pressures (the problems of parasitic contamination)

Antioxidant enzymes are present in sphincter of Oddi nerves and regulate sphincter of Oddi motor function mediated by NO-releasing nerves. Oxygen free radicals (O2-.) produce hydrogen peroxide (H2O2) by the action of superoxide dismutase (SOD). Hydroxyl radical (OH.) has been shown to play an important role as a mediator of H2O2 toxicity. The aims of our study were to determine the effects of H2O2 on sphincter of Oddi motility and if these effects are mediated by OH.. Adult opossums were sacrificed and the sphincter of Oddi removed and placed in a tissue bath containing oxygenated Krebs solution. Force transducers recorded tension in a transverse orientation at two sites along the sphincter of Oddi specimen. H2O2 was added into the tissue bath at concentrations from 0.01 to 0.5%. O2-. radicals were inhibited by the addition of SOD, while OH. was scavenged by the addition of alcohol (ETOH) or dimethyl sulfoxide (DMSO). H2O2 produced a dose-dependent increase in baseline amplitude, frequency, and peak amplitude of contractions. The effect of 0.01% H2O2 on sphincter of Oddi contractile frequency was inhibited by 0.2% ETOH and DMSO, but not by SOD. We conclude that H2O2 has profound effects on sphincter of Oddi motility and that the actions of H2O2 are probably mediated through OH..