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Biomedical subjects

B O'Neill

Publications and source records attributed to B O'Neill.

At least 73 records · Page 4Linked to original sources
PubMed1987

Nonmetric test of the minimax theory of two-person zerosum games.

As an experimental test of the minimax theory for two-person zerosum games, subjects played a game that was especially easy for them to understand and whose minimax-prescribed solution did not depend on quantitative assumptions about their utilities for money. Players' average relative frequencies for the moves and their proportions of wins were almost exactly as predicted by minimax, but subject-to-subject variability was too high. These results suggest that people can deviate somewhat from minimax play since their opponents have limited information-processing ability and are imperfect record keepers, but they do not stray so far that the difference will be noticed and their own payoffs will be diminished.

Game Theory↗
PubMed1986

Ethanol selectively affects Na+-gradient dependent intestinal transport systems.

Moderate concentrations of ethanol reduce the velocity of uptake of three representative Na+-symport systems (D-glucose, L-alanine, L-ascorbate), whether electrogenic (the first two) or electroneutral (L-ascorbate). This 'inhibition' is observed only if these transport systems are tested in the presence of an initial Na+ gradient (out greater than in); no inhibition is found in tracer-equilibrium exchange measurements. A representative Na+-independent system (D-fructose) is not inhibited by ethanol. 'Passive diffusion' (measured as uptake of L-glucose) is increased somewhat by alcohol. All these observations can be rationalized [as suggested by Tillotson et al. (1981) Arch. Biochem. Biophys. 207, 360-370] by an effect of ethanol on passive diffusion, which leads to a faster collapse of the Na+ gradient, with the resulting reduction of the uptake velocities of Na+-dependent transport systems when tested with the added driving force of an Na+ out----in gradient.

Alanine↗
PubMed1986

Perceived risks and driving behavior.

Claims have been made that safer cars result in drivers who take more risks. However, there are two basic design changes that make cars safer: the first reduces the likelihood of a crash; the second reduces the chance of injury during a crash. Because design changes that reduce the likelihood of a crash also often provide direct and immediate feedback, drivers may change their behavior, although there is no evidence that the change offsets the benefits of the increased crash avoidance capability. Design changes that increase occupant protection usually provide no direct and immediate feedback and, therefore, should have no effect on driving behavior. The data are consistent with this hypothesis and contradict the hypothesis of risk compensation.

Accidents, Traffic↗
PubMed1985

A prospective study between carbamazepine, phenytoin and sodium valproate as monotherapy in previously untreated and recently diagnosed patients with epilepsy.

One hundred and eighty one patients with previously untreated epilepsy were randomised to sodium valproate, phenytoin or carbamazepine as monotherapy and followed up for a median period which ranged from 14 to 24 months. All three drugs were highly effective in the control of generalised seizures but less effective for partial seizures. Excellent or good control was achieved with therapeutic levels of sodium valproate and carbamazepine, but with subtherapeutic levels of phenytoin.

Adolescent↗
PubMed1984

A two-active site one-polypeptide enzyme: the isomaltase from sea lion small intestinal brush-border membrane. Its possible phylogenetic relationship with sucrase-isomaltase.

The enzyme responsible for all of the isomaltase activity and much of the maltase activity in the small intestine of the Californian sea lion (Zalophus californianus) was isolated by detergent solubilization of the brush-border membrane, followed by immunoadsorption chromatography using antibodies directed against rabbit sucrase-isomaltase. In 0.1% Triton X-100, sea lion isomaltase occurs as a monomer of Mr = 245,000 and is composed of a single polypeptide chain. As judged from the stoichiometry of the covalent binding of the affinity label, conduritol-B-epoxide, this polypeptide chain carries two enzymatically active sites; they are apparently identical and do not show either positive or negative cooperativity. In addition to cross-reacting immunologically with rabbit sucrase-isomaltase, sea lion isomaltase has similar overall enzymatic properties, with the exception of not hydrolyzing sucrose. The Alaskan fur seal (Collarhinus ursinus) has a two-active site isomaltase; however, in contrast to the sea lion, this animal is endowed with a small but significant sucrase activity. Along with (fully active) pro-sucrase-isomaltase, sea lion isomaltase is one of the very few examples of enzymes with more than one active site on a single polypeptide chain acting "in parallel" (rather than "in series"). Furthermore, this enzyme triggers some interesting questions on the phylogenetical pedigree of small intestinal sucrase-isomaltase.

Animals↗
PubMed1984

Effect of infusion of nutrient solutions into the ileum on gastrointestinal transit and plasma levels of neurotensin and enteroglucagon.

The small bowel transit time of 100 ml of lactulose solution infused at the ligament of Treitz was measured by breath hydrogen excretion in paired studies carried out in 43 healthy volunteers during infusion (1.2 ml/min) of equal volumes (100 ml) of isotonic solutions of either fat emulsion (Intralipid, Prosparol, or Calogen), protein hydrolysate, glucose, or saline into either the jejunum (90 cm from the teeth), ileum (205 cm from the teeth), or colon (350 or 400 cm from the teeth). Ileal infusion of Intralipid or protein hydrolysate resulted in significant delays in small bowel transit time (125 +/- 21 min and 71 +/- 11 min, respectively) compared with infusion of saline (50 +/- 3 min; p less than 0.02 and p less than 0.05). These delays were not associated with any significant alteration in plasma levels of neurotensin or enteroglucagon. Small bowel transit time was unaffected by infusion of nutrients into the colon or jejunum, although jejunal infusion of Intralipid increased the plasma levels of enteroglucagon and neurotensin (p less than 0.01 and p less than 0.02, respectively) after the start of lactulose infusion. In a separate series of paired experiments, infusion of Intralipid into the ileum in 5 volunteers significantly delayed the transit of a solid test meal labeled with 25 microCi of 99mTc-sulfur colloid through both the stomach and small intestine. These data support the existence of a mechanism whereby the presence of unabsorbed food in the ileum may enhance absorption by delaying the passage of food through the small intestine.

Adult↗
PubMed1983

Passenger car size and driver seat belt use.

The National Highway Traffic Safety Administration (NHTSA) claims, on the basis of survey results, that seat belt use in small cars is twice as high as in large cars. The agency interprets this as being due in part to perceptions of higher risk by small car occupants. In fact, little is known about the factors motivating belt use, including whether risk perception is important. A reanalysis of the NHTSA data indicates that most of the differences in belt use by car size can be explained by higher use in imported cars, and by geographical differences in belt use in domestic cars.

Automobiles↗
PubMed1983

Genetics of xenotropic virus expression in mice. II. Expression of major virus structural proteins in crosses involving NZB/B1NJ, SWR/J, and 129/J strains of mice.

The expression of viral structural polypeptides and the production of infectious xenotropic virus were found to segregate together in NZB, 129/J, and SWR/J mice and in crosses between these strains. The viral p30 protein segregation pattern, as measured by competition radioimmunoassay using extracts of frozen spleens from backcross progeny, indicate that xenotropic murine leukemia virus expression is controlled by two dominant genes.

Animals↗
PubMed1982

Serum elevation of high density lipoprotein (HDL) cholesterol in epileptic patients taking carbamazepine or phenytoin.

Serum lipids and the cholesterol concentration in the high density lipoprotein (HDL) fraction were measured in epileptic patients taking either carbamazepine or phenytoin as single drug treatment. There was a significant increase in HDL-cholesterol levels in patients taking both phenytoin and carbamazepine. Serum total-cholesterol concentrations in patients taking both drugs did not differ significantly from those of controls. The ratio of HDL-cholesterol/total cholesterol was increased in both drugs and the increase reached significance in patients taking phenytoin. There was a significant increase in serum triglycerides in females taking carbamazepine.

Adolescent↗