Anaesthesia and the obese patient

The obese patient is likely to have pre-operative impairment of cardiovascular and respiratory function. These impairments will tend to increase in the per- and post-operative period and place the patient at risk of myocardial ischaemia and hypoxaemia. The physical effects of obesity mean that all patients require endotracheal intubation during anaesthesia and this may be difficult to achieve. The difficulties in moving and positioning the patient and difficulties in gaining access for monitoring and venous cannulation add to the problems. Anaesthesia and surgery may present a considerable risk for obese patients and should not be undertaken without full understanding of the potential problems.

Psychological and war stress symptoms among deployed and non-deployed reservists following the Persian Gulf War

The present study examined the incidence of war-related psychological distress among Persian Gulf War veterans. A total of 591 Army, Navy, and Marine reservists were administered the Mississippi PTSD Scale, the Beck Depression Inventory, and the SCL-90R. Combat-deployed reservists showed significantly higher levels of psychological symptomatology that non-deployed reservists, generally corresponding to levels of stress exposure. No significant effects were found for race or prior combat exposure, but significant differences were found between combat-deployed male and female reservists. Despite the brevity and the outcome of the Persian Gulf War, significant symptomatology exists among this population.

Chorismate mutase:prephenate dehydratase from Acinetobacter calcoaceticus. Purification, properties and immunological cross-reactivity

The bifunctional P protein (chorismate mutase: prephenate dehydratase) from Acinetobacter calcoaceticus has been purified. It was homogeneous in polyacrylamide gels and was more than 95% pure on the basis of the immunostaining of purified P protein with the antibodies raised against the P protein. The native enzyme is a homodimer (Mr = 91,000) composed of 45-kDa subunits. A twofold increase in the native molecular mass of the P protein occurred in the presence of L-phenylalanine (inhibitor of both activities) or L-tyrosine (activator of the dehydratase activity) during gel filtration. Chorismate mutase activity followed Michaelis-Menten kinetics with a Km of 0.55 mM for chorismate. L-Phenylalanine was a relatively poor non-competitive inhibitor of the mutase activity. The chorismate mutase activity was also competitively inhibited by prephenate (reaction product). Substrate-saturation curves for the dehydratase activity were sigmoidal showing positive cooperativity among the prephenate-binding sites. L-Tyrosine activated prephenate dehydratase strongly but did not abolish positive cooperativity with respect to prephenate. L-Phenylalanine inhibited the dehydratase activity, and the substrate-saturation curves became increasingly sigmoidal as phenylalanine concentrations were increased with happ values changing from 2.0 (no phenylalanine) to 4.0 (0.08 mM L-phenylalanine). A sigmoidal inhibition curve of the dehydratase activity by L-phenylalanine gave Hill plots having a slope of -2.9. Higher ionic strength increased the dehydratase activity by reducing the positive cooperative binding of prephenate, and the sigmoidal substrate-saturation curves were changed to near-hyperbolic form. The happ values decreased with increase in ionic strength. Antibodies raised against the purified P protein showed cross-reactivity with the P proteins from near phylogenetic relatives of A. calcoaceticus. At a greater phylogenetic distance, cross-reaction was superior with P protein from Neisseria gonorrhoeae than with that from the more closely related Escherichia coli.

Oxygen and hydrogen isotopes in fruit and vegetable juices

(18)O/(16)O ratios from the juices of a number of fruits and vegetables were measured and found to be isotopically more enriched than the water in which they grew. Fast-growing high-water-content vegetables exhibited less enrichment than slower growing fruits such as apples, pears, and plums. (18)O/(16)O measurements were also made on the water from various sections of several plants, and the enrichment was found to occur in the following order: leaves > fruit > stem >/= ground water.D/H and (18)O/(16)O measurements were made on a series of grape juice samples and, when plotted against each other, gave a slope of 3.9, indicating that the physical process causing this enrichment was probably evaporation, i.e. evapotranspiration.

Mechanism of induction of RNA tumor viruses by halogenated pyrimidines

Frome these studies on JLS V-9 cells, a number of conclusions can be drawn about the mechanism of MuLV induction by halogenated pyrimidines. The compounds can induce virus from otherwise healthy cells as long as deoxycytidine is present along with the inducing agent. The compounds must be present during the S phase of the cell cycle and must be incorporated into DNA in order to induce virus (Teich et al. 1973). Only one strand of DNA need be substituted by BrdU or IdU in order to induce virus, because a one-hour period of incorporation leads to induction. From these results it is possible to construct a model for how halogenated pyrimidines are able to induce viruses from otherwise uninfected cells. Because the critical period for the incorporation of the compound is a restricted segment of the S phase of the cell, there would appear to be a critical segment of the genetic information of the cell which, when substituted with BrdU or IdU, leads to a transcriptional derepression. Presumably the critical segment of DNA is either a controlling element of the integrated provirus or it is a separate gene which controls the expression of the integrated provirus. Whichever is true, these results strongly imply that the search for specific repressors of the segments of mammalian DNA is likely to be successful and that RNA tumor viruses may offer a system in which such repression systems can be identified and investigated.