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Biomedical subjects

K R Holmes

Publications and source records attributed to K R Holmes.

49 records · Page 3Linked to original sources
PubMed1980

Thermoregulation in Telazol (CI-744)-anesthetized rhesus monkey (Macaca mulatta).

Seven Telazol (CI-744)-[Telazol is an experimental drug (Parke, Davis) composed of two ingredients in equal amounts by weight: tiletamine HCl, designated chemically as 2-(ethylamino)-2-(2-thienyl)cyclohexanone-HCl, and zolazepam HCl, designated as 4-(o-fluorophenyl)-6,8-dihydro-1,3,8-trimethylpyrazolo-3,4-e 1,4 diazepin-7(IH)-one monohydrochloride] anesthetized rhesus monkeys (Macaca mulatta) were exposed to ambient temperatures (Ta) of 15, 23, 29, 35, and 38 degrees C to evaluate the effect of this dissociative anesthetic agent on thermoregulation. Thermal equilibrium in both anesthetized and control animals at Ta 15 degrees C was through peripheral vasoconstriction and metabolic heat production (M); shivering increased M in the anesthetized group to 1.7 times the resting M of 41.4 W x m-2. Both groups at Ta 38 degrees C regulated body temperature by vasodilation and increased skin evaporative heat loss (Esk) due to sweating. Anesthetized animals increased Esk from 6.4 W x m-2 at Ta 29 degrees C to 32.5 W x m-2 at Ta 38 degrees C. Panting was not observed in either group. Effective tissue thermal conductance was lowest at Ta 15 and 23 degrees C (6.9 and 7.6 W x m2 x degrees C-1, respectively), and increased with Ta's above 23 degrees C (45.0 W x m-2 at Ta 38 degrees C). These results indicate that Telazol-anesthetized monkeys maintain thermal balance at ambient temperatures from 15 to 38 degrees C, and that Telazol induces little or no impairment of thermoregulation in rhesus monkeys.

Anesthesia↗
PubMed1976

Chain elongation and desaturation of palmitic acid in liver microsomes of rats subjected to hyperbaric exposure.

The enzyme activities associated with chain elongation and desaturation of fatty acid in hepatic microsomes from rats held at 1 ATA of air, 1 ATA of He-O2, and 20 ATA of He-O2 were studied. It was found that both the microsomal chain elongation and desaturation of fatty acids were depressed in rats held at 1 ATA of He-O2 as compared to animals held at 1 ATA of air. When animals were exposed to an environment of 20 ATA of He-O2, the chain elongation of fatty acid was about the same as for rats held at 1 ATA of air and was two times greater than for the rats held at 1 ATA of He-O2. The desaturase activity was depressed as compared to the two groups of control animals held at 1 ATA of air and 1 ATA of He-O2.

Air Pressure↗
PubMed1976

Sex determination of the lesser bushbaby (Galago senegalensis).

The gross anatomy of the external genitalia of newborn to adult lesser Galago was described. The penis is perpendicular to the body wall at birth and by about 8 wk of age the testes have descended into the scrotum. In the adult male the testes are permanently descended, the scrotum sessile, the penis is oriented obliquely rostral, and the genitalia are covered by luxuriant pelage. In the young female, the clitoris is also perpendicular to the body wall and the labia and vaginal orifice, although not obvious, are located at its caudal base. In the adult female, the clitoris remains perpendicular, is slender, essentially devoid of fur, and has the urethral opening in its tip. The labia and vaginal orifice are at its caudal base, obscured by fur. Effective and reliable methods for differentiating males from females were outlined.

Animals↗
PubMed1975

Epidermal thermal conductivity and stratum corneum hydration in cat footpad.

Epidermal thermal conductivity (k) was calculated for the cat footpad by measuringtransepidermal heat flux and temperature gradient (¿T) while changes in stratum corneum water content were produced by "internal hydration" (IH; eccrine sweat gland activity by nerve stimulation) or by "external hydration" (HH; exposure to air saturated with water vapor). In some experiments, cutaneous vasoconstriction accompanying IH was prevented by an alpha-adrenergic receptor blocking agent, phenoxybenzamine (POB), 3.52 mg/kg iv. For dry skin k=0.167 plus or minus 0.023 (SE) W.m (-1) degree C (-1). With and without POB, IH produced 49.5% and 17.2% increases in k, respectively; HH after IH did not increase k more. With POB, IH increased k more than did HH alone (49.5% and 15.5%, respectively) and at a higher rate (4.22 times 10 minus 3 and 0.63 times 10 minus 3 W.m minus 1.degree C minus 1. min minus 1, respectively.) As k increased, usually deltaT decreased. Increasing k and decreasing deltaT with skin hydration explain the phenominon that air temperature is felt to be lower the more humid a cold exposure, since the temperature of thermoreceptors at the dermoepidermal junction is closer to that of the skin surface when the corneum is hydrated than when it has a low water content.

Animals↗
PubMedDate not supplied

Insonation of fixed porcine kidney by a prototype sector-vortex-phased array applicator.

The sector-vortex applicator, an ultrasound phased array with a geometric focus having multiple sectors and tracks, can directly synthesize, without scanning, diffuse focal patterns useful for hyperthermia. A perfused tissue phantom, consisting of an alcohol-fixed porcine kidney with thermocouples placed in the cortex, is insonated by a prototype sector-vortex applicator with 16 sectors and two tracks at an ultrasound frequency of 750 kHz. Steady-state temperature distributions are measured for a wide range of perfusion rates. Results demonstrate that the radius of the heated region can be controlled effectively by choosing the focal mode of the applicator as it is predicted by theoretical analysis.

Animals↗
PubMedDate not supplied

Thermoregulation in the canine prostate during transurethral microwave hyperthermia, Part I: Temperature response.

In this research, experiments were performed to study thermoregulation in the canine prostate during microwave hyperthermia. The transurethral thermal therapy (T3) system provided by Urologix, Inc. was used to impose microwave heating in the canine prostate. Five types of temperature responses to different microwave power levels as time varies, including both damped and sustained oscillatory temperature responses, have been observed. Decreases in prostatic tissue temperature during the microwave heating are believed to be caused by the increase in local blood flow stimulated by tissue temperature elevations. In this study, the characteristic temperatures and time associated with each response. This work will help to provide a better understanding of how tissue temperature is regulated within the canine prostate during transurethral microwave hyperthermia. Results of the present study offer an experimental foundation for a more detailed theoretical analysis on the temperature distribution based on the power input and local blood perfusion.

Animals↗
PubMedDate not supplied

Thermoregulation in the canine prostate during transurethral microwave hyperthermia, Part II: Blood flow response.

Recent studies on transurethral-applied local hyperthermia in both the canine and human prostate have revealed significant effects of natural thermoregulation on the therapeutical results in the prostate. Using a thermal clearance method, blood perfusion rates were measured within different regions in the canine prostate under normal and hyperthermic conditions. It has been found that the canine-prostatic blood perfusion is strongly linked to the geometrical location within the gland, the local tissue temperature, and the imposed thermal dosage. Results from this research are expected to provide a better understanding of the thermoregulatory behaviour in the canine prostate, and thus lay an important foundation for predicting tissue temperature in the human prostate during transurethral microwave hyperthermia.

Animals↗
PubMedDate not supplied

Comparison of push-pull versus discard method from central venous catheters for blood testing.

This article evaluates recent research results comparing two different methods for obtaining complete blood cell counts and chemistry profiles from central venous catheters. Complete blood cell count and chemistry profile samples were obtained from 25 patients at three hospital-based infusion clinics. The results indicate no appreciable difference between these two methods. Minimizing risks of blood loss, blood exposure to healthcare personnel, potential specimen contamination, and erroneous reporting are benefits of the push-pull method.

Adult↗
PubMedDate not supplied

Risks associated with 72- and 96-hour peripheral intravenous catheter dwell times.

BACKGROUND: The risk of complications in peripheral intravenous therapy is higher on the second day of therapy and may continue to increase with time, making routine restarts after 3 days a common practice. The objective of the study was to determine whether the risks of complications after a peripheral i.v. catheter restart after 72 hours are less than the risks of complications if the therapy is continued to 96 hours. METHODS: A retrospective chart review was completed for 722 patients in a community hospital with peripheral i.v. catheters for i.v. fluids or saline locks. Measurements collected were i.v. therapy start date, number of restarts, termination date, and reason for termination; the data were analyzed using risk models. RESULTS: There were 596 uncomplicated therapies. Complications prompted termination in 188 cases. The average duration of therapy was 1.8 days. The probability of complications was least in the first 24 hours, (0.074; standard deviation [SD], 0.013), and increased to 0.176 (SD, +/- 0.026) in the 24- to 48-hour period. The probability of a complication in the 48- to 72-hour period and the 72- to 96-hour period was 0.130 (SD, 0.026). A restarted catheter has a significantly higher risk of complication in its first 24 hours than does an initial catheter. CONCLUSIONS: From these results, the authors conclude that restarting catheters at 72 hours does not reduce the risk of complication in the next 24 hours when compared with simply continuing the therapy with the original catheter. Additional studies should be conducted to justify a policy of automatically restarting therapy after 72 hours.

Catheterization, Peripheral↗