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Biomedical subjects

A W Hahn

Publications and source records attributed to A W Hahn.

At least 109 records · Page 6Linked to original sources
PubMed1977

Cardiac output, left ventricular ejection rate, plasma volume, and heart rate changes in equine laminitis-hypertension.

Acute laminitis-hypertension was produced experimentally by carbohydrate overloading of the gastrointestinal tract in 8 horses, and the resulting hemodynamic changes were measured. Statistically significant (P less than 0.01) increases in cardiac output, left ventricular ejection rate, heart rate, and arterial pressure were related to statistically nonsignificant changes in peripheral resistance and a delayed (Obel grade 3 plus 24 hours) decrease in plasma volume. When compared with control values, the doubling of cardiac output and left ventricular ejection rate simultaneous with little or no change in either peripheral resistance or plasma volume (16 hours after the occurrence of Obel grade 3 lameness) was suggestive of an increase in myocardial contractility. Because these pathophysiologic phenomena have important time relationships to the onset of Obel grade 3 lameness in acute laminitis, the results of this investigation are discussed in light of their relationship to clinical signs, serum electrolyte changes, plasma L-lactate alterations, and histologic deterioration of the digit.

Animals↗
PubMed1975

Castration and other factors affecting the risk of equine laminitis.

The characteristics of a series of equine laminitis cases were compared with that of other Equidae examined at the University of Missouri Veterinary Hospital and Clinic during May, 1965 through December, 1971. The model age for ponies with laminitis was 7-9 years and for all other cases the model age was 4-6 years. Also the predominant age for mares was 4-6 years and for males was 7-9 years. After controlling for age and breed differences, there were significantly fewer castrated males among the affected males than expected (P small than 0.02), indicating that hormonal factors may play a role in laminitis. Ponies had a significantly greater risk of laminitis (P smaller than 0.001) and their relative risk was 4.3 times greater than all other Equidae combined. There were more laminitis cases diagnosed during May than during other months.

Age Factors↗
PubMed1975

Equine laminitis of alimentary origin: an experimental model.

Acute alimentary form of laminitis was uniformly induced in 11 of 12 horses by administration of a starch and wood flour gruel and could be graded by previously established (Obel) and presently defined criteria. The experimentally induced laminitis was similar to naturally occurring laminitis, as determined on the basis of lameness severity and vital signs. Packed cell volume, leukocyte count, and total protein were significantly increased (P smaller than 0.05) at 24 and 40 hours after administration of gruel. Arterial systolic and diastolic pressures increased, central venous pressure decreased, heart rate increased, and rectal temperature increased consistently within the 56-hour experimental period. Of the 11 affected horses, 7 horses had Obel grade 3 lameness (horse moved most reluctantly and vigorously resisted attempts to lift a forefoot) at 40 hours after gruel was placed in the alimentary tract, 2 horses had Obel grade 3 lameness at 32 hours, and 2 horses had Obel grade 3 lameness at 48 hours.

Administration, Oral↗
PubMed1975

Indirect blood pressure measurement in the dog.

The validity of the ultrasonic Doppler technic for indirectly measuring arterial blood pressure over a wide range was tested in anesthetized dogs. Correlation coefficents of 0.99 and 0.97 for systolic and diastolic pressure were verified on the basis of 316 comparisons of direct and indirect measurements. Utility of the method for detecting hypotensive, normotensive, and hypertensive arterial blood pressures was demonstrated. Potential applications of the method by life scientists and veterinarians includes routine monitoring of anesthesia, characterization of disease, and documentation of pharmacologic states.

Anesthesia↗
PubMedDate not supplied

Variations on the response characteristics of oxygen electrodes.

To summarize: The works presented in this and the previous paper (2) have produced an operational model for describing the oxygen reduction process in common medical grade sterile saline media at a platinum disc shaped electrode with a fairly specific surface conditioning. This paper has illustrated some of the variations possible in electrode current responses. An important feature of these data is that they are highly consistent and repeatable and can be discussed in terms of the model. However, the question still remains: What is the aging process? Is it due to a decrease of active sites for the electrochemical reduction process, brought about by the reduction process itself, or is it a process caused by other species in the media? To answer these questions, it may be necessary to employ some of the sophisticated techniques such as angle-resolved photoelectron spectroscopy (4) and extended x-ray absorption fine structure (5), available today for the study of atomic and molecular arrangements on solid surfaces.

Isotonic Solutions↗