Modelling myocardial ischaemia and reperfusion.

Substrate depletion and increased intracellular acidity are believed to underlie clinically important manifestations of myocardial ischaemia. Recent advances in measuring ion concentrations and metabolite changes have provided a wealth of detail on the processes involved. Coupled with the rapid increase in computing power, this has allowed the development of a mathematical model of cardiac metabolism in normal and ischaemic conditions.

Anaesthetic management of the morbidly obese patient.

Morbidly obese patients are prone to many clinical conditions that can effect anaesthesia. Of major concern to the anaesthetist are difficulties with airway management and abnormalities of cardiorespiratory function. Safe anaesthesia requires an appreciation of potential problems and a thorough understanding of the pathophysiological changes that accompany morbid obesity.

Effects of ketorolac and dextran-70 alone and in combination on haemostasis.

Background: Dextran may be used in surgical patients for thromboprophylaxis or volume expansion along with ketorolac, a nonsteroidal anti-inflammatory drug, for analgesia. As these two agents can influence the haemostatic system at different sites, it is important to demonstrate that there is no adverse haemostatic interaction between them.

Methods: The haemostatic interaction between intravenous dextran-70 and intramuscular ketorolac was assessed in a double-blind, randomised, crossover study of healthy male volunteers each given all four combinations of ketorolac/placebo intramuscularly and dextran/placebo intravenously.

Reduction and integration in understanding the heart.

The heart provides an excellent example of the limits of the reductive approach. Cardiac cells function through the interaction of a very large number of ion transporters, and the processes that link these to metabolic states and to contraction. Yet, the great majority of the advances made recently have been at the cellular and molecular levels.

The effects of sodium substitution on currents determining the resting potential in guinea-pig ventricular cells.

It has recently been shown that a sodium background current, ib,Na, exists in cardiac muscle cells whose effect is to depolarize the membrane so that the resting potential, Vm, is positive to the potassium equilibrium potential, EK. In ventricular cells, where ib,Na is smallest, Vm is about 10 mV positive to EK (EK = -87 mV at 37 degrees C). Yet, replacement of Na+ ions by large impermeant cations does not cause the expected hyperpolarization.

Improved guinea-pig ventricular cell model incorporating a diadic space, IKr and IKs, and length- and tension-dependent processes.

The guinea-pig ventricular cell model, originally developed by Noble et al in 1991, has been greatly extended to include accumulation and depletion of calcium in a diadic space between the sarcolemma and the sarcoplasmic reticulum where, according to contempory understanding, the majority of calcium-induced calcium release is triggered. The calcium in this space is also assumed to play the major role in calcium-induced inactivation of the calcium current. Delayed potassium current equations have been developed to include the rapid (IKr) and slow (IKs) components of the delayed rectifier current based on the data of of Heath and Terrar, along with data from Sanguinetti and Jurkiewicz.

Cellular mechanisms of cardiac mechano-electric feedback in a mathematical model.

Background: Cardiac mechanical and electrical activity are closely interrelated. While excitation-contraction coupling is rather well characterized, less is known about cellular mechanisms that promote mechanically induced changes in cardiac electrical activity--mechano-electric feedback.

Objective: To integrate experimental findings on stretch activation of ion channels and length-dependent changes in intracellular calcium handling into a mathematical description of cardiac cellular activity.

Modelling of sodium-overload arrhythmias and their suppression.

Models of the electrophysiological properties of cardiac cells are now capable of accounting not only for normal activity, but also for some of the mechanisms of arrhythmia. A good example is the reconstruction of the inotropic and arrhythmogenic effects of sodium pump inhibition leading to the generation of ectopic beats. The models can also be used to investigate the possible mechanisms of suppression of arrhythmias.

The effect of divergent selection for total plasma phosphorus in Japanese quail on fearfulness and selected blood and heart parameters.

A selection experiment utilizing Japanese quail was initiated to study the genetic relationship of growth and reproduction traits. In this study, lines were selected for increased (HP line) and decreased (LP line) total plasma phosphorus at the beginning of lay. The HP and LP lines were derived from a randombred control population (R1 line) that was maintained with the selected lines to remove environmental variation over generations.

Organochlorine and heavy metal residues in breast muscle of known-age thick-milled murres (Uria lomvia) from the Canadian Arctic.

Thick-billed murres (Uria lomvia) originating from breeding colonies in the Canadian Arctic were collected on their wintering grounds off the coast of Newfoundland. Murres had been previously banded such that the age of each bird could be determined upon collection. This allowed us to explore the possible relationships between age and contaminant levels in the thick-billed murre.

Influence of crossing a line selected for increased shank width and a commercial sire line on performance and walking ability of turkeys.

The present study was initiated to determine whether walking ability (WA) could be markedly improved without seriously compromising growth rate and body conformation by crossing a relatively unimproved commercial sire line (UC) with a line (FL) selected for increased shank width and backcrossing F1 females to UC line males. Body weights at 8, 16, and 20 wk of age were generally similar for both lines at the time of the initial cross. The UC line had inferior WA, shorter and narrower shanks, and wider breasts compared with the FL line.

Beak trimming of turkeys. 2. Effects of arc beak trimming on weight gain, feed intake, feed wastage, and feed conversion.

An experiment was conducted to study the effects of arc beak trimming on feed consumption, weight gain, and feed wastage in males and females from two large-bodied strains and one medium-bodied strain of turkeys. Birds were placed in wire-floored battery cages from 3 to 8 wk of age and feed intake, weight gains, and feed spilled into dropping pans were recorded for each of the 5 wk of each trial. Feed conversion was calculated as feed consumed divided by weight gained.

An efficient process for production of N-acetylneuraminic acid using N-acetylneuraminic acid aldolase.

N-acetyl-D-neuraminic acid (Neu5Ac) aldolase (EC 4.1.3.

Divergent selection for body weight and yolk precursor in Coturnix coturnix japonica. 12. Heterosis in reciprocal crosses between divergently selected lines.

A selection experiment was started using Japanese quail to study the genetics of BW and plasma yolk precursor (measured by total plasma phosphorus; TPP). Lines were divergently selected for 4-wk BW (HW and LW) or plasma TPP (HP and LP). Sublines of HW were developed by continuing to select the males for increased 4-wk BW while selecting the females for increased (HW-HP line) or decreased (HW-LP line) TPP.

Genetics of growth and reproduction in the turkey. 13. Effects of repeated backcrossing of an egg line to two sire lines.

The objective of the present study was to determine the feasibility of rapidly increasing the BW of dam lines by repeated backcrossing of a dam line to a sire line. A line (E) selected long-term for increased egg production was backcrossed to a line (F) selected long-term for increased 16-wk BW (BC1) and to a commercial sire line (BC2). The BW of the F and commercial sire lines were about twice as large as that of the E line.

Readiness: observations and comments from a medical team deployment.

The evolving strategy of the United States in dealing with the changing world order calls for a force structure capable of fighting and winning two nearly simultaneous major regional conflicts and conducting a range of other military operations. Readiness is a key factor in this new strategy. Consequently, major paradigm shifts are occurring within the Air Force Medical Service.

Modeling of internal pH, ion concentration, and bioenergetic changes during myocardial ischemia.

Arrhythmias are caused by the interdependent processes of change in energy metabolism and alterations in sarcolemmal ion gradients that occur during ischemia. Depletion of energy metabolites and increased proton concentrations in ischemic heart may underlie the observed phenomena of reduced contractile force and also of malignant ventricular arrhythmias that can lead to tachycardia and ventricular fibrillation. Recent advances in measuring changes in ion concentrations and metabolites during cardiac ischemia have provided a wealth of detail on the processes involved.

The effect of beak trimming on two strains of commercial tom turkeys. 2. Behavior traits.

The influence of beak trimming of two strains of commercial male turkeys (Strains A and B) on behavior during the growing period was investigated. Poults were either left with beaks intact or arc beak trimmed at hatching. Strain by beak treatment interactions were generally lacking, indicating that these two strains responded similarly.

Effect of altering the early dietary protein level on males from two strains of commercial turkeys.

Two trials were conducted in which male turkeys from commercial Strains A and B were fed diets calculated to contain 80, 100, or 120% of recommended levels of protein from 1 to 8 wk of age and recommended levels of protein at other ages. Feeding reduced protein diets decreased 8-wk BW of both strains. No difference in BW, however, was evident at 17 wk in either strain.

Direct and correlated responses to long-term selection for increased body weight and egg production in turkeys.

Lines of turkeys were selected long-term for increased egg production (E line; 34 generations) or increased 16-wk BW (F line; 28 generations). The E and F lines were started from randombred control populations (RBC1 and RBC2, respectively) that were also maintained to remove environmental variation among generations. Realized heritabilities (h2) +/- SE in the E line, based on regressions of response on cumulated actual selection differentials (selection differentials weighted for the number of offspring produced), for 180-d and 250-d egg production were 0.

Influence of growth selection in turkeys on resistance to Pasteurella multocida.

Four lines of turkeys, a randombred control (RBC2) started in 1966 and three sire lines (F, A, and B), were challenged with a field isolate of Pasteurella multocida (capsular serogroup A, somatic serotype 3, 4) at 6 wk of age. Line F, a subline of the RBC2 line, was selected for 28 generations for increased 16-wk BW and Lines A and B were primary breeding sire lines from two commercial breeders. Each bird was inoculated subcutaneously in the back of the neck with 1.