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Biomedical subjects

L Weaver

Publications and source records attributed to L Weaver.

At least 55 records · Page 3Linked to original sources
PubMed1987

The economic benefit of treating subclinical Streptococcus agalactiae mastitis in lactating cows.

The economic benefits of treating lactating cows for Streptococcus agalactiae mastitis were studied at a large (689 milking cows) central California dairy. Postcure milk production of case cows (infected, treated, and cured) was compared with production of paired control cows (uninfected) and was matched for yield, days in milk, days in gestation, and parity. A simulation was used to plot expected lactation curves for mastitic cows (infected, not treated) with characteristics similar to those of each control cow, and these curves were compared with actual case-cow lactation curves. The difference in actual and expected production was used to calculate net economic benefits of treatment. Comparison of expected with actual production indicated a net benefit from treatment of $396/cow for cows treated in early lactation and $237 for cows treated in midlactation, but a net loss of $55 for cows treated in late lactation. Lactation number did not have a significant impact on economic benefits of treatment. In contrast to other studies indicating no economic benefit from treating mastitis during lactation, this study's positive results may have been attributable to the high cure rate (98%) and the subclinical form of mastitis being treated. Streptococcus agalactiae mastitis treatment during early and midlactation would appear to be an economically justifiable option for dairy managers.

Animals↗
PubMed1987

Cardiovascular effects of afferent renal nerve stimulation.

Electrical stimulation of afferent renal nerves elicits an increase in arterial pressure and heart rate. The hypertensive response is presumably due to the widespread activation of the sympathetic nervous system leading to peripheral vasoconstriction. Interestingly, the kidney does not appear involved in this reflex excitatory response to afferent renal nerve stimulation since changes in vascular conductances and excretory functions are equal in both the innervated and denervated kidney, and secondary to changes in renal perfusion pressure. In addition, no changes in renin release from either kidneys are observed during afferent renal nerve stimulation. It is likely that the electrical stimulation of afferent renal nerves activates other reflexes exerting an inhibitory influence on efferent renal nerve activity. Indeed, neural renorenal reflexes which tonically inhibit renal functions have clearly been demonstrated. Furthermore, preferential inhibition of efferent renal nerve activity by cardiopulmonary and sinoaortic receptors has recently been shown during activation of other visceral afferents.

Afferent Pathways↗
PubMed1985

Reliability of a standardized brief-pulse stimulus in ECT.

The reliability of a standardized brief-pulse stimulus in eliciting a satisfactory convulsive response was evaluated under normal clinical conditions. A total of 89 patients were given 961 initial treatments. Of these, 757 were at the standardized level with a success rate of 89%. A total of 204 trials were given at higher-than-standardized levels. Treating these as standardized level failures, the overall success rate was 70%. The probability that a standardized stimulus given to any patient at any point in the treatment series would be successful was about 7 chances in 10. Implications for the selection of ECT stimuli were discussed.

Adolescent↗
PubMed1979

Histogenesis of the so-called "intravascular bronchioloalveolar tumour".

Three cases of Dial and Liebow's intravascular bronchioloalveolar tumour are described, with emphasis on ultrastructure and histogenesis. The tumour cells are quite different from adjacent reactive alveolar cells and electron microscopy does not support the suggested alveolar cell origin. The tumour cells contain abundant microfilaments, moderate amounts of rough endoplasmic reticulum and varying numbers of Weibel-Palade bodies. With features of smooth muscle, myofibroblast and endothelial cell differentiation, a vascular origin from precursor mesenchymal cells such as the vasoformative reserve cells is suggested.

Adult↗
PubMed1978

The threshold number of pulses in bilateral and unilateral ECT.

Using a low-energy brief-pulse stimulus, the threshold number-of-pulses required to produce a bilaterally manifested tonic-clonic seizure with unilateral and bilateral electrode placement was investigated. Unilateral placement required significantly fewer pulses; bilateral placement resulted in greater post-ictal confusion with no apparent advantage in clinical efficacy. A possible explanation in terms of intracerebral current density is proposed.

Adult↗
PubMed1976

Current density in bilateral and unilateral ECT.

This paper describes a method of computer simulation which will enable the researcher to test, on the theoretical level, the effects of a wide variety of electrode placements, currents, tissue resistivities, and volumetric differences on the distribution of current within the brain. It is based on a nonhomogenous, threesphere model of the head and is capable of expansion to account for known inhomogenities within the brain. It should prove a useful research tool for a wide variety of purposes.

Computers↗
PubMed1975

Utilization of medical services by transferred employees. Differential effect of life change on health.

Some of the health consequences of being transferred to a new job and a new community were examined. The medical records of transferred employees for one year following transfer were compared to the records of a matched control group of more permanently located employees. Because of the authors' clinical observation that an employee's job description was related to the medical response to transfer, the professional and nonprofessional (production and clerical) employees were examined as separate groups. The results demonstrated a greater utilization of health services by transferred nonprofessional, but not by transferred professional employees. The results are discussed in the light of current research in life changes and their relationship to illness.

Adaptation, Psychological↗