Reaction and total cross sections for low energy pi + and pi - on isospin zero nuclei

We calculated the electrostatic force between a planar interface, such as a planar-supported lipid bilayer membrane, and the tip of a stylus on which another lipid bilayer or some other biomacromolecular system might be deposited. We considered styli with rounded tips as well as conical tips. To take into account the effect of dynamical hydrogen-bonded structures in the aqueous phase, we used a theory of nonlocal electrostatics. We used the Derjaguin approximation and identified the systems for which its use is valid. We pointed out where our approach differs from previous calculations and to what extent the latter are inadequate. We found that 1) the nonlocal interactions have significant effects over distances of 10-15 A from the polar zone and that, at the surface of this zone, the effect on the calculated force can be some orders of magnitude; 2) the lipid dipoles and charges are located a distance L from the hydrophobic layer in the aqueous medium and this can have consequences that may not be appreciated if it is ignored; 3) dipoles, located in the aqueous region, can give rise to forces even though the polar layer is unchanged, and if this is ignored the interpretation of force data can be erroneous if an attempt is made to rationalize an observed force with a knowledge of an uncharged surface; 4) the shape of the stylus tip can be very important, and a failure to take this into account can result in incorrect conclusions, a point made by other workers; and 5) when L is nonzero, the presence of charges and dipoles can yield a force that can be nonmonotonic as a function of ionic concentration.     

Detection of protein A produced by Staphylococcus aureus with a fiber-optic-based biosensor

Staphylococcus aureus is a pathogen important in causing human infections and intoxication. A sensitive fiber-optic that produces evanescent waves was developed for the detection of protein A, a product secreted only by S. aureus. In the immunosensor, a 40-mV argon-ion laser that generated laser light at 488 nm was used together with plastic optical fiber and antibodies to protein A were physically adsorbed onto the fiber. The principle of the detection involved a sandwich immunoassay with fluorescein isothiocyanate conjugated with anti-(protein A) immunoglobulin G to produce signals of the antigen-antibody reaction. The detection limit was 1 ng of protein A per milliliter. The fiber-optic immunosensor could be used for rapid and specific detection of S. aureus in clinical specimens and foods.     

Homeless youth and their exposure to and involvement in violence while living on the streets

Sick building syndrome is the term given to a heterogeneous constellation of symptoms that affects workers in modern mechanically ventilated office buildings. Although the cause is unknown, there is evidence that the local environment of the work station is an important determinant of symptoms. In this study, investigators examined the effect of a new, individually controlled ventilation system on workers' symptoms. Investigators studied two groups of workers in one mechanically ventilated office building: (1) a control group at whose worksite no intervention was made and (2) an intervention group. The intervention consisted of installation of a device that allowed each worker control over the ventilation supplied to his or her worksite. Just before, and 4 and 16 mo after installation of this device, workers completed self-administered questionnaires regarding occurrence of symptoms. The new ventilation system resulted in higher air velocities, more variable temperatures, and higher concentrations of airborne dust and fungal spores. Four months after installation, workers with the new ventilation system reported fewer symptoms that were (a) work-related (p < .05) and that were work-related and frequent (p < .05); in addition, they reported fewer symptoms that reduced their capacity to work (p < .01). Sixteen months after installation, workers with the new device reported fewer symptoms than at baseline (although not as significantly), and they indicated that the indoor air quality improved their productivity by 11%, compared with a 4% reduction of productivity among the control group of workers (p < .001). Investigators concluded that the new ventilation system, which provided the workers with individual control over ventilation, was associated with important and sustained reduction in symptoms.     

Human C-peptide. Part I: Radioimmunoassay

Synthetic human C-peptide bearing a Tyrosine group at its amino end is labelled with 125iodine using chloramin T or hydrogen peroxide and lactoperoxidase. The results are compared applying both methods. Antiserum to synthetic human C-peptide (without Tyrosine) which was partially compared to rabbit albumin, is raised in guinea pigs and goats. Goats show to be superior to guinea pigs concerning antibody production. The so-called "hook effect" phenomenon is observed in setting up the standard curves for the radioimmunoassay. Monotonically decreasing standard curves are obtained on dilution of antiserum with a high antibody titer which was produced by repeated immunization in goats. Free C-peptide and C-peptide bound to antiserum are separated with the anxion exchange resin Amberlite. Using this separation technique we excluded unspecific binding of labelled C-peptide to protein fractions in serum of diabetics. The sensitivity of our radioimmunoassay is approx. 0.3 ng C-peptide/ml serum. Intra- and interassay variability are below 10%. Human proinsulin is the only substance found to crossreact with the antiserum.     

An analysis of automatic teller machine usage by older adults: a structured interview approach

Sex differences in the activity of aromatase cytochrome P450 (CYP19) in the rat brain have been reported during pre- and postnatal development. It is unclear, however, whether these differences are reflected by corresponding differences in specific mRNA levels. To address this question, we have examined aromatase mRNA levels in specific regions of male and female rat brains by means of in situ hybridization (ISH). At prenatal stages of development, i.e. at gestational day 18 (GD18) and GD20, aromatase mRNA was detected in several preoptic, hypothalamic and limbic brain regions. Semiquantitative analysis of aromatase mRNA did not reveal sex differences in any of these regions. In contrast, clear-cut sex differences were determined at postnatal day (PN) 2; male animals expressed significantly more aromatase mRNA in the bed nucleus of stria terminalis (BST) and the sexually dimorphic nucleus of the preoptic area (SDN). Smaller but still significant differences (females > males) were obtained in the medial preoptic area (MPO). At PN6, sex differences of aromatase mRNA signals (males > females) were still present in the BST, but were no longer detectable in the SDN and the MPO. At PN15 and in adult animals, aromatase mRNA levels were similar in BST and medical amygdaloid nucleus of male and female rats. Since aromatase mRNA expression decreases during postnatal development, no ISH signals could be detected anymore in MPO, SDN and ventromedial hypothalamic nucleus. Our results are consistent with the concept that differential regulation of aromatase mRNA expression might be important for the establishment of different neuronal circuitry in male and female animals.     

Bronchoscopic evaluation of pulmonary infiltrates following bone marrow transplantation

Mutants of human prothymosin alpha with impaired ability to inhibit yeast Saccharomyces cerevisiae. cerevisiae cell growth were characterized. Two types of prothymosin alpha-inactivating mutations were observed. Mutations that belong to the first type compromised the nuclear entry of prothymosin alpha by affecting its nuclear localization signal. Analysis of subcellular distribution of GFP-prothymosin alpha fusions revealed a bipartite nuclear localization signal that is both necessary and sufficient for nuclear import of the protein in human cells. Mutations of the second type abrogated the inhibitory action of prothymosin alpha through an unknown mechanism, without influencing the nuclear import of the protein.