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Biomedical subjects

J M Price

Publications and source records attributed to J M Price.

139 records · Page 8Linked to original sources
PubMedDate not supplied

Hemodynamics and left ventricular function: a comparison between adult racing greyhounds and greyhounds completely untrained from birth.

Trained racing greyhounds are known to have cardiomegaly, higher mean arterial pressure and cardiac indices and lower systemic arterial resistances at rest than mongrel dogs. In order to distinguish between those hemodynamic and left ventricular functional characteristics that are inborn in the greyhound as opposed to those which are acquired through training, we studied 9 adult (mean age 22.9 +/- 4.2 [S.D.] months) trained racing greyhounds within 8 days of the cessation of training and 9 adult greyhounds raised under sedentary conditions (mean age 21.7 +/- 1.4 months). Seven healthy adult mongrel dogs served as additional controls. Right and left heart catheterizations of chloralose-anesthetized animals included hemodynamic and left ventricular functional measurements before and after volume loading with 500 ml 6% dextran in normal saline. Heart weight/body weight ratios were the same in both trained and untrained greyhounds, favoring the concept that the cardiomegaly of greyhounds is genetic and not acquired. Trained greyhounds had significantly decreased systemic vascular resistance, increased cardiac index and stroke volume, and a tendency (non significant) toward elevated systemic arterial pressure in comparison to mongrels. Life-long untrained adult greyhounds had hemodynamic measurements that did not differ from mongrels; they also had significantly higher systemic vascular resistances and lower cardiac indices than trained greyhounds. Some hemodynamic characteristics of the trained adult greyhound dog are not present in completely untrained greyhounds and are the result of either training alone or training superimposed on genetic predisposition.

Animals↗
PubMedDate not supplied

Analyses of single-trial N1 amplitude and latency variability and their influence on the average evoked potential.

Sixteen adult subjects listened to tone pips superimposed on Bach concertos and either attended to the tones or to the music. Auditory evoked potentials (EPs) were recorded to the tones in both conditions from C3 and C4 each referenced to linked ears. Although the expected Condition X Hemisphere interaction was not found, a main effect for Condition showed that N1 amplitude in the average EPs (AEPs) was greater in the Tones condition. P2 showed no significant main effects or interactions. The AEP was used as a template to identify N1 in each single-trial wave form. The difference in AEP amplitude between conditions was subsequently found to be due primarily to enhanced N1 amplitude in the single-trial wave forms, and not to a decrease in latency variability. This template-matching procedure appears to be a valid method for identifying N1 in single-trial wave forms based on the following findings: (1) multiple regression analyses demonstrated that 90-99% of the variance of the amplitude of N1 in the average EP could be accounted for by a weighted linear combination of single-trial amplitude and latency variability; (2) the values of the correlation coefficients between the AEP template and the single-trial EPs were generally very high, averaging approximately +0.91; (3) the distributions of the latency of N1 in the single-trial EPs were not flat as would be expected if random noise were being identified as N1.

Adult↗