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Biomedical subjects

R L Hughes

Publications and source records attributed to R L Hughes.

At least 19 recordsLinked to original sources
PubMed1994

First-year residents' caring, medical knowledge, and clinical judgment in relation to laboratory utilization.

PURPOSE: To investigate first-year residents' levels of caring (concern for others' well-being), medical knowledge, and clinical judgment in relation to their levels of laboratory utilization. METHOD: Self-report questionnaires about caring, knowledge, and judgment were given in 1986-87 to 36 first-year residents in a three-year internal medicine residency program of the McGaw Medical Center of Northwestern University. Inpatient laboratory utilization data obtained from structured chart audits over a one-year period were used to construct comparable diagnosis- and severity-specific physician practice profiles, from which the residents received overall utilization scores for laboratory test charges. Statistical methods included Cronbach's alpha reliability coefficient and multiple regression analysis. RESULTS: The multiple regression analysis showed that medical knowledge was an independent predictor of increased laboratory utilization (standardized beta = .54, p < .04, partial R2 = .07); clinical judgment was an independent predictor of decreased utilization (standardized beta = -.53, p < .05, partial R2 = .06); and caring was unrelated to utilization (standardized beta = .15, ns, partial R2 = .01). CONCLUSION: The finding that clinical judgment was related to less laboratory utilization suggests that future research should investigate the decision-making concomitants of judgment to better understand its translation into resource utilization. It is possible that the relationship between medical knowledge and laboratory utilization is developmentally specific, and thus the knowledge of more experienced physicians, who would likely be more precise decision makers than first-year residents, may be related to decreased rather than increased utilization.

Chicago↗
PubMed1993

Monotreme development with particular reference to the extraembryonic membranes.

This paper considers many of the salient features of monotreme development, particularly morphogenesis of the extraembryonic membranes. The uterine endometrium of both monotremes and marsupials exhibits a progesterone driven luteal phase where accelerated utilization of endometrial nutrients is evidenced by a rapid post-primitive streak expansion in the dimensions of the extraembryonic membranes. Monotremes share with marsupials, birds, and reptiles an unspecialized vertebrate mode of genesis of the embryonic disc on the peripheral surface of the yolk-sac. The fused vascularized respiratory chorioallantois is estimated to have a functional life of not more than the terminal 4 to 5 days of the monotreme incubation period. This time interval is of a slightly greater order of magnitude than that found in marsupials with a fused chorioallantois, so far described, but in the context of the proportional elapse of post-primitive streak organogenesis would fall within the marsupial grade. The dominant extraembryonic membrane for nutritive and respiratory function in both monotremes and marsupials is the yolk-sac. This contribution shows that monotremes and marsupials share a much larger suite of developmental anatomical features than previously reported. The evolutionary biologist is confronted with the challenge of how to assign an appropriate weighting to these features as marsupials are considered by many researchers to be allied phylogenetically more closely with eutherian mammals than with monotremes.

Animals↗
PubMed1993

Different effects of three aldosterone treatments on plasma aldosterone and salt intake.

Adrenalectomized male rats received a nominal dose of 47.6 micrograms/day aldosterone for 14 days by daily injections, osmotic minipumps, or controlled-release pellets. Plasma aldosterone concentrations were barely detectable (< 20 pg/ml) 24 h after rats received aldosterone by injection, remained constant at 200 pg/ml in rats with osmotic minipumps, and dropped from > 500 to 75 pg/ml during the first week after implantation of controlled-release pellets. For the most part, the effects of the different treatments on NaCl intake were related to their effects on plasma aldosterone levels according to a U-shaped function. However, NaCl intake was dissociated from plasma aldosterone levels when treatment first began or was discontinued. NaCl intake may be a function of the amount of aldosterone delivered but not necessarily plasma aldosterone concentration.

Adrenal Glands↗
PubMed1993

Independence of salt intake induced by calcium deprivation from the renin-angiotensin-aldosterone system.

We investigated whether the elevated NaCl intake shown by calcium-deprived rats is mediated by the renin-angiotensin-aldosterone system. First, we looked for manifestations of altered renin-angiotensin-aldosterone system activity during the progression of calcium deficiency. There were no differences between control and calcium-deprived rats in plasma aldosterone concentrations, plasma renin activity, plasma sodium concentrations, sodium balance, or blood pressure. Second, we used selective pharmacological antagonists to examine whether disruption of the renin-aldosterone-angiotensin system influenced salt intake. Blockade of aldosterone receptors with spironolactone (25 mg.kg-1 x day-1 sc for 7 days) had no effect on NaCl intake of control or calcium-deprived rats. Angiotensin AT1 receptor blockade with losartan potassium (0.5-10 mg/kg orally) had no effect on NaCl intake of control or calcium-deprived rats but doses > 0.5 mg/kg decreased NaCl intake of adrenalectomized rats. Taken together, these findings indicate that the renin-angiotensin-aldosterone system does not mediate the increased NaCl intake produced by calcium deficiency. The appetite for salt produced by calcium deficiency involves a different physiological substrate from most other models of NaCl intake.

Adrenalectomy↗
PubMed1993

Independence of salt intake from the hormones regulating calcium homeostasis.

Rats deprived of dietary calcium increase voluntary intake of NaCl solutions. We investigated whether the major hormones controlling calcium homeostasis are responsible for this increase in salt intake. Removing endogenous sources of calcitonin and parathyroid hormone by thyroidectomy and/or parathyroidectomy had no effect on NaCl intake. The surgically compromised rats and their intact controls drank similar amounts of NaCl in response to manipulations of diet calcium content. Despite normal NaCl intakes, rats with parathyroidectomy had low plasma calcium concentrations and a strong appetite for 50 mM CaCl2 solution. Chronic infusion of parathyroid hormone into rats with thyroparathyroidectomy decreased NaCl intake. Intact rats fed an American Institute of Nutrition (AIN)-76A-based vitamin D-deficient diet increased NaCl intake slightly and showed a strong appetite for CaCl2, but other rats maintained normocalcemic by the addition of calcium, phosphorus, and lactose to the vitamin D-deficient diet had normal NaCl and CaCl2 intakes. Chronic infusions of 1,25-dihydroxyvitamin D3 into intact rats had no effect on NaCl intake. Taken together, these results indicate that the increase in NaCl intake produced by calcium deprivation is not mediated by changes in circulating levels of calcium, calcitonin, parathyroid hormone, or 1,25-dihydroxyvitamin D3. Furthermore, the major calcium-regulating hormones are not involved in the control of "spontaneous" NaCl intake in the rat.

Animals↗
PubMed1992

Actinomycetales infections in slender-horned gazelles: six cases (1987-1989).

Disseminated Actinomycetales infections were diagnosed in 6 slender-horned gazelles at a zoologic park over a 17-month period. Nocardia and Mycobacterium spp were isolated. Possible predisposing causes leading to infection were investigated. Environmental contamination where the gazelles were housed was not high, and other breeds of gazelles at the park did not become infected, indicating that environmental exposure was not the sole factor involved. Information gathered from questionnaires sent to other zoologic parks and personnel communications indicated that this was not an isolated incident. Investigation into the genetic lineage of the gazelles revealed substantial inbreeding in prior generations. These findings suggested inbreeding may have been an important predisposing factor leading to infection. Careful scrutiny to ensure maximal heterozygosity of future breedings is warranted.

Actinomycetales Infections↗
PubMed1992

Ultrastructure and distribution of epidermal sensory receptors in the beak of the echidna, Tachyglossus aculeatus.

Within the rostral one centimetre of the Echidna beak, three specialised receptors were found: a mucous sensory gland, a rod-like structure, and an innervated epidermal pit. The mucous sensory gland consists of a dermal mucous gland and a modified epidermal portion. Bulbous nerve terminals, similar to those reported for the Platypus, were found within the modified epidermal portion of the mucous gland. The rod-like structure contains four types of nerve terminals: Merkel cells, Paciniform corpuscles, and a central and a peripheral vesicle chain receptor. Apart from minor differences, the rod-like structure is similar to that previously reported for the Platypus. Preliminary results are presented for a third structure: an innervated epidermal pit. Topographical and ultrastructural analyses are used in the context of functional interpretation.

Animals↗
PubMed1991

Gentamicin and vancomycin removal by continuous venovenous hemofiltration.

The dispositions and dose requirements for vancomycin and gentamicin were investigated in a 58-year-old man who was receiving long-term continuous venovenous hemofiltration. Estimates of clearance were obtained using a Bayesian parameter estimation program and stayed remarkably consistent throughout the therapy. Single daily doses of both vancomycin and gentamicin generally maintained the profiles for both drugs around the target ranges of peak 5-10 mg/L (gentamicin) and 25-40 mg/L (vancomycin) and trough less than 2 mg/L (gentamicin) and less than 10 mg/L (vancomycin).

Bayes Theorem↗
PubMed1990

Impairment of theophylline clearance by a hypocaloric low-protein diet in chronic obstructive pulmonary disease.

The effect of a hypocaloric, low protein diet on theophylline kinetics was studied in a 70-year-old man with chronic obstructive pulmonary disease who lost 6.2 kg of weight. Total systemic clearance, unbound clearance, and intrinsic hepatic clearance fell dramatically. Theophylline elimination half-life rose from 8.4 to 17.1 h. Therefore, a diet deficient in both calories and protein can significantly impair theophylline clearance and prolong theophylline elimination half-life.

Aged↗
PubMed1990

Comparison of enflurane and halothane in hypotensive eye surgery.

Thirty patients undergoing elective eye surgery had anaesthesia induced with sodium thiopentone, suxamethonium and d-tubocurarine chloride. Patients were ventilated with nitrous oxide, oxygen and either halothane or enflurane. The volatile agents were used to decrease the systolic blood pressure to 80 mmHg. The volatile agent concentration in the blood was measured at 30 min intervals. Both agents were effective in producing hypotension, but enflurane was the more potent hypotensive agent in terms of MAC equivalents. There was no significant differences between the agents with respect to speed of recovery.

Adolescent↗
PubMed1989

Longer hospitalization at Veterans Administration hospitals than private hospitals. Verification and additional insights.

Utilizing 1,297 male patients under the primary care of an identical group of house officers and under treatment between 1985 and 1987 for ten common medical diagnoses, length of hospitalization was compared between a private sector (n = 481) and Veterans Administration (VA) (n = 816) facility, both affiliated with the same medical school. All patients were rated by the Horn Severity of Illness Index. After researchers controlled for diagnosis, severity of illness, age, race, and physician, results in this study indicate that an additional 3.2 days of hospitalization were associated with the VA facility. This finding is consistent with earlier reports of inappropriate hospitalization at the VA hospital and suggests that VA facility planners need to evaluate whether longer lengths of stay (LOS) are merited.

Adult↗
PubMed1989

Cerebral blood flow determination within the first 8 hours of cerebral infarction using stable xenon-enhanced computed tomography.

Cerebral blood flow mapping with stable xenon-enhanced computed tomography (Xe/CT) was performed in conjunction with conventional computed tomography (CT) within the first 8 hours after the onset of symptoms in seven patients with cerebral infarction. Six patients had hemispheric infarctions, and one had a progressive brainstem infarction. Three patients with very low (less than 10 ml/100 g/min) blood flow in an anatomic area appropriate for the neurologic deficit had no clinical improvement by the time of discharge from the hospital; follow-up CT scans of these three patients confirmed infarction in the area of very low blood flow. Three patients with moderate blood flow reductions (15-45 ml/100 g/min) in the appropriate anatomic area had significant clinical improvement from their initial deficits and had normal follow-up CT scans. One patient studied 8 hours after stroke had increased blood flow (hyperemia) in the appropriate anatomic area and made no clinical recovery.

Aged↗