Biomedical subjects
Publications and source records attributed to R M Smith.
The major arylhydroxy metabolite of cocaine in human urine was identified as 4'-hydroxybenzoylecgonine methyl ester by comparison of mass spectral and relative gas-liquid chromatography retention time data of metabolites in patient samples with those of the three synthesized positional isomers. The 3'-hydroxy isomer was also identified in most samples, but its concentration varied widely from sample to sample.
3'-Hydroxy- and 4'-hydroxybenzoylecgonine ethyl ester (IIb and IIc) and 4'-hydroxy-3'-methoxybenzoylecgonine ethyl ester (IIh) were identified in basic extracts of urine samples from patients who had used cocaine and ethanol concurrently. Identification was based on comparison of patient gas chromatography and mass spectrometry data with those of synthesized standards. These findings corroborate earlier work in which the corresponding methyl esters of these metabolites were found in the same urine samples.
PURPOSE: The limited clinical availability of currently used methods to measure regional cerebral blood volume (CBV) and cerebral blood flow (CBF) represents an important restriction. We undertook this study to evaluate a new dynamic CT method to measure CBV and CBF in normal and ischemic tissue. METHOD: A total of 21 dynamic CT studies were performed in seven male beagles. The contrast enhancement curves of the carotid arteries and of various brain regions were deconvolved to obtain CBV and CBF. The stability of the deconvolution method employed was assessed by comparing three data sets obtained by analyses of one, two, and four regions of interest (ROIs), all covering the entire brain area. The accuracy of CT-derived CBF was analyzed for normal (n = 5 studies) and ischemic (n = 7 studies) brain tissue using fluorescent microspheres. Repetitive CT studies were performed to evaluate the precision of the CT measurements. RESULTS: The stability of the deconvolution method was high with variabilities of 2.3% (CBV), 5.9% (CBF), and 8.9% (mean transit time), respectively. The correlation between the CT and the microsphere measurements was good for both normal and ischemia studies (r > 0.78, slope > 0.9). The variability of the CT CBF (30.6%) was higher than that of the CT CBV (12.3%) measurements. CONCLUSION: Our novel dynamic CT method is stable with respect to the sizes of ROIs used, allowing for accurate measurements of CBV and CBF in both normal and ischemic tissue. Further studies are necessary to evaluate the variability of this method under controlled physiologic conditions.
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The suitability of plasma catecholamines (CAs) and neuropeptide-Y (NPY) as biochemical indices of sympathetic nerve activity (SNA) has been investigated, and these parameters have been compared between adult normotensive (WKY) and stroke-prone spontaneously hypertensive rats (SHRSP). Plasma norepinephrine (NE), epinephrine (E) and NPY were measured in venous and arterial blood samples taken from conscious, unrestrained rats. Under resting conditions, both CAs were significantly higher in SHRSP than in WKY; plasma E in particular was raised threefold. SHRSP had higher plasma levels of NPY in arterial blood but not in venous blood. Acute hydralazine-induced hypotension caused a slight rise in NPY and striking increases of CAs, which were accentuated in SHRSP. Ganglion blockade with pentolinium reversed these increases but the differences in basal plasma CA levels between strains still persisted. Barbiturate anaesthesia had little effect on plasma levels of NPY or NE, but plasma E levels were depressed, particularly in SHRSP, so that the strain difference in plasma E taken from venous blood was no longer apparent. The results indicate that plasma levels of CAs but not NPY are useful indices of SNA in conscious rats. Comparisons between WKY and SHRSP after drug treatment demonstrate a major contribution by the adrenal medulla to plasma CA levels in SHRSP which, under resting conditions, may not be sympathetically evoked.
As healthcare delivery moves into ambulatory and community-based settings, nurses need preparation for professional-level practice in these new environments. The University of Arkansas for Medical Sciences (UAMS) College of Nursing has designed and implemented its own ambulatory care nursing course to educate nurses for this growing practice setting. The author discusses the design and implementation of the courses.
The possibility that serotonin (5HT) nerve endings in the dorsomedial medulla oblongata participate in the control of blood pressure was investigated in stroke-prone hypertensive rats and in normotensive rats. 5HT nerves were destroyed by injecting 5,7-dihydroxytryptamine bilaterally into the solitary tract nucleus. Immunohistochemical and biochemical examination revealed a selective loss of 5HT nerves throughout the dorsomedial medulla with little damage in adjacent regions. Arterial blood pressure and heart rate, measured at daily intervals, were similar in lesioned and sham-operated normotensive rats. However, in the hypertensive rats, blood pressure was substantially elevated at 6-9 days after the lesions compared with sham operations. There were no accompanying changes in heart rate.
The influence of chronic alcohol consumption on blood pressure was examined in normotensive Wistar/Kyoto rats (WKY) and in stroke-prone spontaneously hypertensive rats (SHR-SP). Ethanol, administered in drinking water from 5 weeks of age to produce moderate blood alcohol levels, substantially retarded the development of hypertension in SHR-SP and caused a mild reduction of blood pressure in WKY. Alcohol withdrawal caused an acute rise in blood pressure in both strains, followed by a reduction to the subnormal levels previously induced by alcohol treatment. This sustained antihypertensive effect of alcohol was not attributable to reductions of body weight or fluid intake.
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The effects of a thiamine-deficient diet on plasma and tissue vitamin concentrations and on whole-body glucose metabolism were assessed. Male Sprague-Dawley rats (175 to 200 g body weight) fed a thiamine-deficient (TD) or nutritionally complete purified diet were used for plasma thiamine mononitrate and monophosphate and for red blood cell and tissue thiamine pyrophosphate (TPP) determinations weekly for up to 5 weeks. Additional rats were used for assessment of basal glucose kinetics by using a primed constant infusion of [3-3H]glucose. Plasma thiamine mononitrate levels decreased 60% at 1 week and were undetectable after 5 weeks on the diet. Plasma thiamine monophosphate decreased 80% after 1 week on the TD diet, and levels were undetectable after 4 weeks on the diet. Red blood cell TPP in the TD group decreased progressively with time: 54% at 1 week, 86% at 3 weeks, and 92% at 5 weeks. At 1 and 4 weeks, the decrease in tissue TPP was significant in the liver (65% and 89%, respectively), gut (52% and 94%, respectively), spleen (40% and 60%, respectively), and skeletal muscle (37% and 76%, respectively), with the brain (7% and 84%, respectively) showing the slowest initial rate of depletion. The TD diet did not alter plasma glucose concentrations, but it increased plasma lactate by 75% and plasma pyruvate by 50% to 75%. Rates of hepatic glucose production and peripheral glucose utilization were not different between the control and TD rats at 2 weeks, but they were 25% higher in the TD rats after 6 weeks on the diet.(ABSTRACT TRUNCATED AT 250 WORDS)
To permit early recognition of possible cord trauma due to spinal fusion with Harrington-rod instrumentation, 42 patients were awakened introperatively for testing voluntary motor function of the limbs. N2O-O2-curare and morphine were used for anesthesia in all patients. In 5 patients, who refused IV induction, halothane was given for induction only. Only 1 patient had any complaint referrable to being awakened intraoperatively. The awakening caused no displacement of Harrington rods in any patient. No neurologic sequelae were found.
Incidence of and contributory factors in postintubation laryngeal edema were determined in 7875 children under 17 years of age. Data were assembled in the manner of a prospective study. With an overall incidence of 1 percent, children between ages 1 and 4 were most susceptible. Excessive size of the endotracheal tube was suspect in half of the cases. Other factors that increase trauma to the larynx while an endotracheal tube is in place showed significant correlation to the total incidence of postintubation laryngeal edema. No tracheostomies were required.
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This study used biochemical and quantitative ultrastructural approaches to examine the roles that insulin receptor beta subunit kinase activity, the NPEY motif in the juxtamembrane region, and tyrosine phosphorylation within that domain plays in insulin-accelerated receptor-mediated insulin internalization in CHO cells. Internalization of insulin in cells that expressed kinase-deficient receptors (CHOA1018) or receptors lacking the NPEY Ala954-Asp965 domain (CHO delta 960) was reduced by 80% compared to cells expressing wild-type human insulin receptors (CHOHIRc). Ultrastructural analysis revealed that the decreased internalization in CHOA1018 cells was due to the reduced ability of the kinase deficient receptor to migrate from the microvilli of cultured cells and aggregate on the cell surface. Deletion of the NPEY motif in the juxtamembrane region of the beta subunit severely reduced receptor migration, interfered with the normal aggregation of receptors on the cell surface, and virtually eliminated accumulation of the occupied receptors in the coated invaginations. Replacement of Tyr960 in the NPEY domain/with phenylalanine (CHOF960) had no significant effect on insulin internalization, receptor mobility, aggregation or accumulation in coated invaginations. In contrast, replacement of Tyr960 with alanine (CHOA960) decreased insulin internalization, slowed migration, receptor aggregation and accumulation in coated invaginations. These studies document that kinase activity is required, but not sufficient, for receptor movement from the microvilli and aggregation of occupied receptors on the non-villous surface. An intact NPEY motif or surrounding amino acids, but not the phosphorylation of Tyr960 plays a role in receptor mobility and aggregation and is essential for the accumulation of insulin receptors in coated invaginations.
Population-based surveillance for Vero cytotoxin-producing Escherichia coli (VTEC) O157 has been carried out in Wales since 1990. The annual incidence has remained stable during the 9-year period (mean: 1.6 cases per 100,000 population); the rate is highest in children younger than 5 years of age. Blood in the stool is reported in fewer than half the cases, indicating the importance of screening all fecal specimens for VTEC O157.
A case of pulmonary dirofilariasis in a 62-year-old female was diagnosed by fine needle aspiration biopsy. A review of the literature revealed this to be the first reported case diagnosed by this method. The presence of bilateral lesions in this patient is an uncommon finding for this entity.
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