Conduction studies on Ta2O5 layer under different metallic electrodes

Rectification studies on Ta₂O₅ anodic oxide layers with vacuum-deposited Au, Ag, Pb, Bi, Sb contacts have been made. No correlation between critical voltage and work function for metal electrodes was found. Non-uniform and unpredictable behaviour of Ta₂O₅ films under different metals have indicated the dominant dependence of conduction on the flaw density in the oxide film.     

Human joint performance and the roughness of articular cartilage

The Doppler technique has been used to evaluate venous reflux in the spermatic cord. Valsalva-induced reflux occurred on the left side in 83% and on the right side in 59% of 118 patients without clinical varicoceles and there was no difference in incidence between fertile and infertile men. The significance of Valsalva-induced reflux should be questioned. Greater importance should be attributed to the spontaneous venous reflux that occurred during quiet respiration in the majority of patients with varicoceles. Seven velocity waveform patterns are described and these are thought to represent increasing degrees of internal spermatic vein reflux and provide a basis on which it is possible to grade varicoceles. The Doppler grades correlated with the size of the varicocele, and with the internal spermatic vein diameter and testosterone concentrations.     

Reversal of pretreatment hypotension and control of hemorrhage in trauma patients by a simple device

The injection of a suspension of Walker 256 carcinoma cells into the carotid artery of rats produced a model of hematogenously spread cerebral metastases. Most animals died from massive extracerebral tumors of the head and jaw; brain tumors were present in only one-quarter. External carotid artery ligation prior to tumor inoculation did not increase the incidence of fatal brain tumor. When cyclophosphamide, 15 mg/kg, was injected as a single dose on the fourteenth day after tumor inoculation, most of the extracerebral tumor disappeared. Fifty percent of the animals so treated were cured of tumor, but 90% of the remainder died of large intracerebral tumors. Severe cytopathic changes resulting from cyclophosphamide were present in extracerebral or choroid plexus tumors but were mild or nonexistent in intracerebral tumors. These selective effects of cyclophosphamide suggest that water-soluble agents are less effective against tumor in the brain than against extracerebral tumors despite the fact that metastatic tumor breaks down the blood-brain barrier.     

RNA tertiary structure mediation by adenosine platforms

The crystal structure of a group I intron domain reveals an unexpected motif that mediates both intra- and intermolecular interactions. At three separate locations in the 160-nucleotide domain, adjacent adenosines in the sequence lie side-by-side and form a pseudo-base pair within a helix. This adenosine platform opens the minor groove for base stacking or base pairing with nucleotides from a noncontiguous RNA strand. The platform motif has a distinctive chemical modification signature that may enable its detection in other structured RNAs. The ability of this motif to facilitate higher order folding provides one explanation for the abundance of adenosine residues in internal loops of many RNAs.     

Gonadal steroids have paradoxical effects on brain oxytocin receptors

Specific brain receptors for oxytocin have been described in several mammalian species. The distribution of these receptors differs greatly across species and in the rat, receptor binding in specific brain regions appears to depend upon gonadal steroids. This study used in vitro receptor autoradiography to examine the effects of testosterone on oxytocin receptor binding in the mouse forebrain. Three groups of male mice were compared: castrates treated with blank capsules, castrates treated with testosterone filled capsules, and intact males. Irrespective of steroid treatment, the distribution of oxytocin receptors in mouse forebrain differed markedly from patterns previously described in the rat. In addition to these species differences in receptor distribution, testosterone had effects in the mouse which differed from the induction of receptors previously reported in the rat. In the mouse ventromedial nucleus of the hypothalamus, binding in the untreated castrate males was approximately double that observed in either the intact or the testosterone-treated castrates. In other regions of the mouse brain, such as the intermediate zone of the lateral septum, binding to oxytocin receptors was increased with testosterone treatment. These results suggest that the brain oxytocin receptor varies across species not only in its distribution but also in its regional regulation by gonadal steroids. These apparently paradoxical changes in oxytocin receptor binding may result from either direct or indirect effects of gonadal steroids in mouse brain.     

Multitrait estimation of genetic parameters of lactation curves in Holstein heifers

Weekly milk yields of 1022 Holstein heifers from 61 sires were used to derive coefficients of the lactation curves using modified gamma and inverse polynomial functions. The natural logarithm of a modified gamma function was ln(yn) = ln (a) + b ln (n) + cn + u sin (x) + v cos (x), where a, b, c, u, and v are coefficients to be estimated; n is the day of lactation; and x is the day of year. Estimates of a, b, and c were combined to define persistency [-(b + 1) ln c], week of peak yield (b/c), and peak yield [a(b/c)be-b]. The inverse polynomial function was n/yn = A0 + A1n + A2n2, where A0, A1, and A2 are coefficients to be estimated. Variance and covariance components for the coefficients of the lactation curve were estimated by the multitrait restricted maximum likelihood method using canonical transformation. Heritability estimates were ln (a) .11, b .07, c .04 u .01, v .04, A0 .28, A1 .26, A2 .21, persistency .21, week of peak .18, peak yield .23, and 308-d milk yield .41. Genetic correlations indicated that selection for faster rate of increase to peak production would result in higher 308-d milk production, higher peak yield, and greater persistency.     

Predictors of long-term smoking cessation in head and neck cancer patients

Cigarette smoking is a major risk factor for head and neck cancer, and individuals who continue to smoke past diagnosis and treatment are at elevated risk for further disease. In a randomized controlled trial, a state of the art provider-delivered smoking cessation intervention was compared to a usual care advice control condition. The intervention consisted of surgeon- or dentist-delivered advice to stop smoking, a contracted quit date, tailored written materials, and booster advice sessions. Subjects were 186 patients with newly diagnosed first primary squamous cell carcinomas of the upper aerodigestive tract who had smoked cigarettes within the past year. At randomization, 88.2% of subjects were current smokers. At 12-month follow-up, 70.2% of subjects completing the trial (n = 114) were continuous abstainers; among baseline smokers alone the continuous abstinence (CA) rate was 64.6%. The cotinine validation rate at 12 months was 89.6%. Modeling techniques were utilized in order to derive expected CA rates, which included noncompleter subjects (n = 72). The CA rate expected at 1 year for the entire patient population was 64.2%, and for smokers alone the expected CA rate was 59.4%. Logistic regression analysis carried out on baseline smokers identified predictors of 12-month CA status. These included medical treatment, stage of change, age, nicotine dependence, and race. The intervention effect was not significant, although the sign of the effect was positive. Based on these findings, we recommend systematic brief advice to stop smoking for head and neck cancer patients, with a stepped care approach for patients less able to quit.