Gender differences in job strain, social support at work, and psychological distress.

Using the demand-control-support model of job strain, the authors examined gender differences in the relationship between psychosocial work exposures and psychological distress in a cross-sectional sample of 7,484 employed Canadians. Compared with low-strain work, high-strain and active work were associated with a significantly higher level of distress in both men and women. Differences in psychological distress in relation to psychosocial work exposures were greater for men than for women. Low social support was associated with higher distress across all categories of job strain, and the combined effect of low social support and high job strain was associated with the greatest increase in distress. This pattern was similar in men and women. This study suggests that psychosocial work exposures may be a more significant determinant of psychological well-being in male workers compared with female workers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Contactless determination of the efficiency of interfacial charge separation in a TiO2/phenylene vinylene polymer junction

We have used the flash-photolysis time-resolved microwave conductivity technique (TRMC) to monitor charge separation between a smooth film of anatase TiO₂ (ca 80 nm) and spin-coated layers of a dialkoxyphenylene-vinylene polymer (20–140 nm thick) on nanosecond flash-photolysis in the polymer absorption band at 544 nm. The quantum efficiency of electron injection into the TiO₂ from photons absorbed in the polymer layer can be calculated by comparing the conductivity resulting from 544 nm irradiation with that from direct band gap excitation of the anatase layer at 308 nm. The maximum efficiency per incident photon, is ca 6% for thicknesses in the range of 30–50 nm of the polymer layer. Charge separation persists well into the microsecond region.     

Amplification of the effectiveness of acetylcholinesterase for detoxification of organophosphorus compounds by bis-quaternary oximes

Pretreatment of rhesus monkeys with fetal bovine serum acetylcholinesterase (FBS AChE) provides complete protection against 5 LD50 of organophosphate (OP) without any signs of toxicity or performance decrements as measured by serial probe recognition tests or primate equilibrium platform performance (Maxwell et al., Toxicol Appl Pharmacol 115: 44-49, 1992; Wolfe et al., Toxicol Appl Pharmacol 117: 189-193, 1992). Although such use of enzyme as a single pretreatment drug for OP toxicity is sufficient to provide complete protection, a relatively large (stoichiometric) amount of enzyme was required in vivo to neutralize OP. To improve the efficacy of cholinesterases as pretreatment drugs, we have developed an approach in which the catalytic activity of OP-inhibited FBS AChE was rapidly and continuously restored, thus detoxifying the OP and minimizing enzyme aging by having sufficient amounts of appropriate oxime present. The efficacy of FBS AChE to detoxify several OPs was amplified by addition of bis-quaternary oximes, particularly 1-(2-hydroxyiminomethyl-1-pyridinium)-1-(4-carboxyaminopyridinium) -dimethyl ether hydrochloride (HI-6). When mice were pretreated with sufficient amounts of FBS AChE and HI-6 and challenged with repeated doses of O-isopropyl methylphosphonofluridate (sarin), the OP was continuously detoxified so long as the molar concentration of the sarin dose was less than the molar concentration of AChE in circulation. The in vitro experiments showed that the stoichiometry of sarin:FBS AChE was higher than 3200:1 and in vivo stoichiometry with mice was as high as 57:1. Addition of HI-6 to FBS AChE as a pretreatment drug amplified the efficacy of enzyme as a scavenger of nerve agents.     

Effect of substituted benzoylglycines (hippurates) and phenylacetylglycines on p-aminohippurate transport in dog renal membrane vesicles

The effect of substituted benzoylglycines (hippurates) and phenylacetylglycines on the transport of p-aminohippurate (PAH) was studied in basolateral (BLMV) and brush border membrane vesicles (BBMV) isolated from dog kidney cortex. The probenecid-sensitive part of 100 microM [3H]PAH uptake into BLMV and BBMV was measured in the presence and absence of 5 mM glycine conjugate. The benzoyl- and phenylacetylglycines studied were substituted in the 2-, 3-, or 4-position with an H, CH3, OCH3 or OH group. Benzoylglycines were stronger inhibitors of PAH transport than phenylacetylglycines and the inhibitory potency of the conjugates was in general lower against the transporter in BBMV than BLMV. The specificities of the transporters in both membranes appear to be very similar. The inhibitory potency of the benzoylglycines, expressed as the apparent inhibition constant (logKi), did not show a linear relationship with their lipophilicity as determined by reversed phase HPLC. Deviation from linearity was caused mainly by the 3-OH and 4-OH analogs, which showed a greater inhibitory potency than expected from their lipophilicity. Phenylacetylglycines only showed a small variation in logKi values, indicating that insertion of a CH2 group between the ring and the carbonyl practically abolishes the influence of the ring and its substituents. In conclusion, both hydrophobic and electronic properties are important determinants of affinity for the PAH transport system. An additional partially negative hydroxyl group in the ring, located preferably at the 3- or 4-position, increases the interaction with the transport system.     

Subnanosecond pulsing of a 3-MV Van de Graaff electron accelerator by means of a passive coaxial pulse shaper

A passive coaxial pulse shaper has been developed which produces a subnanosecond duration pulse with short rise and decay time from a long pulse with short rise time. The mechanical construction of the pulse shaper is a modified coaxial air line T-section. The pulse shaper has been incorporated in the pulsing circuit of a 3-MV Van de Graaff accelerator. The form of the resulting electron beam pulses was monitored both as the charge collected by a coaxial target and as the Cerenkov light emitted by a quartz plate. In both cases sequential sampling techniques were used. The electron beam pulses were found to have rise and decay tiems of approxiamtely 100 ps and a half-width as short as approximately 200 ps could be obtained. An advantage of this method of producing subnanosecond beam pulses is that it does not interfere with normal nanosecond pulsed operation of the Van de Graaff.     

Optical probes and transducers

Biosensors are by definition a combination of a biological receptor compound and a physical or physicochemical transducer. Therefore, the transducing structure is a critical part of every biosensor. In the development of new and improved biosensing layers the importance of the transducing structure is not restricted to the substrate to which biological structures have to be coupled. A field of even greater importance is the use of transducers as probes providing information on the structure and function of biosensing layers, and their relation to a transducer surface. The aim of this paper is to give an overview on optical transducer principles and optical (surface) analytical techniques relevant as part of biosensing structures as well as probes in the development and optimisation of biosensing layers. Categories discussed are basic optical effects, materials involved, surface chemistry, the principal and technological limits of spatial resolution, and sensitivity. The intimate relation between the spatial resolution of a probe, the resulting size of interaction areas, and the feasibility of array structures is pointed out. Two interferometric methods are presented in principle, and their application to biosensing and some results are discussed in detail. The necessity to characterise receptor layers to get detailed information about the interaction process is pointed out. The close relationship between optimal characterisation of layers by selection of adequate probe technologies and improvement of probe performance, and the development of new biosensing layers is discussed. Finally, an outlook is given for future aspects of improved spatial resolution and multianalyte detection.