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Biomedical subjects

R A Nelson

Publications and source records attributed to R A Nelson.

At least 37 records · Page 2Linked to original sources

Effects of cigarette smoking through a partially occluded filter.

The effects of a commercially available corn syrup solution that is applied to the filter end of a cigarette causing an occlusive barrier to cigarette smoke were evaluated. The manufacturer claims that the solution reduces exposure to nicotine, carbon monoxide (CO), and other constituents of tobacco smoke and may aid in smoking cessation by providing a means of gradual nicotine dose reduction. Nineteen volunteers (10 men) smoked commercial cigarettes treated with 0, 1, 2, or 3 drops of the corn syrup solution in a double-blind, crossover experiment. Increases in plasma nicotine after smoking averaged 13.3, 10.5, 9.7, and 6.0 ng/ml in the 0, 1, 2, and 3 drop conditions, respectively. In the 3 drop condition, there was a significant reduction in exhaled CO levels. Subjects reported increased difficulty in cigarette draw and a trend toward decreased strength as a function of the number of drops applied. Cardiovascular and EEG measures of smoking were not significantly affected by the application of the drops. Cigarettes treated with 0, 1, 2, or 3 drops of the solution were machine smoked using methods of the Federal Trade Commission (FTC); nicotine yields were 1.0, 1.0, 0.78, and 0.73 mg of nicotine. These results indicate that Take Out drops reduce exposure to nicotine and other constituents of tobacco smoke from a single cigarette.

Adult↗

The acute pain service: effective or expensive care?

The effect of introducing an Acute Pain Service into a District General Hospital was evaluated by conducting an audit of pain, emesis, sleep and satisfaction before and after inception. A total of 1518 questionnaires were collected; in which surgical patients had been asked to assess their experience pre- and postoperatively. The introduction of an Acute Pain Service significantly (p < 0.0001) improved in-patient perception of pain relief upon return of consciousness after anaesthesia and for 2 days postoperatively, when compared with the experience before its inception. The incidence of emetic sequelae did not increase and both patient satisfaction (p < 0.001) and sleep pattern (p < 0.05) in hospital were significantly improved. An estimate of the economic benefit suggests that the development of Acute Pain Services may be cost effective as well as providing an improved quality of service for patients undergoing surgery.

Adult↗

Dexpanthenol enemas in ulcerative colitis: a pilot study.

OBJECTIVE: To test the hypothesis that topical administration of pantothenic acid, a precursor of coenzyme A, might result in increased tissue levels of coenzyme A, improvement of fatty acid oxidation, and amelioration of ulcerative colitis. MATERIAL AND METHODS: In an open-label pilot study, three patients with active left-sided ulcerative colitis received nightly enemas that contained 1,000 mg of dexpanthenol for 4 weeks. Before and after the study, patients submitted stool specimens for short-chain fatty acid analysis and urine collections for measurement of pantothenic acid and dicarboxylic acids; they also underwent flexible sigmoidoscopy for procurement of biopsy specimens for histologic examination and measurement of colonic coenzyme A activity. A clinical disease activity index and histologic disease activity index were used to assess response. RESULTS: Despite increases in urinary pantothenic acid, no significant changes were found in colonic tissue coenzyme A concentrations, fecal short-chain fatty acid concentrations, or urinary dicarboxylic acid concentrations. Moreover, no significant changes in clinical or histologic disease activity were noted. Although stool frequency and rectal bleeding remained unchanged, all patients noted increased abdominal cramping, and one patient had an increased extent of disease. CONCLUSION: Topically administered dexpanthenol seems to be absorbed, but at the dose used in this study, it did not influence concentrations of colonic coenzyme A activity, fecal short-chain fatty acids, or clinical response in patients with active left-sided ulcerative colitis.

Administration, Topical↗

Alcohol, tobacco and recreational drug use and the risk of non-Hodgkin's lymphoma.

A population based case-control study was conducted to determine whether risk of non-Hodgkin's lymphoma (NHL) in the absence of HIV infection is related to the previous use of tobacco, alcohol or recreational drugs. A total of 378 residents of Los Angeles County who were diagnosed with high- or intermediate-grade NHL were compared with individually age-, race- and sex-matched neighbourhood control subjects with regard to history of use of tobacco products, alcohol and ten specific recreational drugs. Risk of NHL among women decreased with increased consumption of alcoholic beverages (trend P = 0.03), with risk 50% lower among those consuming five or more drinks per week than among non-drinkers. Cocaine, amphetamines, Quaaludes and lysergic acid diethylamide (LSD) were each associated with a significantly increased risk of NHL in men with risk greater among those with more frequent use of these drugs. Confounding factors could not be excluded in these findings. The use of multiple types of drugs was also associated with a significantly increased risk of NHL in men (trend P = 0.005) with risk greatest among those using five or more types of drugs (odds ratio = 5.8, 95% confidence limits = 1.2-28.4); among these drugs, cocaine use appeared to account for the elevated risk of NHL among men based on multivariable analyses.

Adolescent↗

Endothelin-receptor antagonist FR 139317 reduces infarct size in a rabbit model when given before, but not after, coronary artery occlusion.

Endothelins are potent vasoactive peptides that exist as isoforms having different affinities for two main receptor subtypes, ETA and ETB. Based on their potential to produce adverse effects as a result of marked vasoconstrictor actions, these mediators have been widely studied to investigate their role in disease states involving the cardiovascular system. In this study, we examined the effect of a selective ETA-receptor antagonist, FR 139317, on myocardial infarct size by using a rabbit arterial-occlusion model. The main coronary artery of 32 New Zealand white rabbits was occluded for 60 min, followed by 3 h of reperfusion. Sixteen animals received FR 139317 (5.0 mg/kg as a bolus + 30 mg/kg given over a 90-min period), whereas the remaining 16 control rabbits received the drug vehicle. Treatment began at 15 min before coronary artery occlusion and ended at 15 min after the start of tissue reperfusion. Infarct size, expressed as a percentage of the area at risk of infarction, was 64 +/- 4% in the control group and 41 +/- 2% in the treated animals (p < 0.001). In a second set of rabbits, five animals received the same treatment regimen and were compared with five controls; however, unlike the initial protocol, treatment was initiated 45 min after coronary artery occlusion (15 min before reperfusion) and ended after 75 min of reperfusion. In this case, infarct size was 65 +/- 4% in the control group and 56 +/- 10% in the animals that received FR 139317 (NS). The results suggest that endothelin is involved in the extension of myocardial infarction in this rabbit model and that its primary action is manifest during occlusion of the coronary artery.

Animals↗

Sympathoinhibitory response to clonidine is blunted in patients with heart failure.

To determine whether alpha2-adrenergic-mediated sympathoinhibition was altered in chronic heart failure, sympathoinhibitory sensitivity was assessed using the alpha2-adrenergic agonist clonidine in 7 patients with heart failure and in 10 healthy control subjects. Basal norepinephrine spillover was significantly higher in patients with heart failure (1.3+/-0.3 microg/min) than in control subjects (0.7+/-0.1 microg/min, P=.05). Compared with control subjects, the decrement in norepinephrine spillover to cumulative doses of clonidine (1, 2, and 3 microg/kg administered intravenously) was significantly less in patients with heart failure (P<.05). Blood pressure also tended to decrease less in patients with heart failure (P=.06). The doses of clonidine required to produce a 10% decrease in blood pressure and a 25% decrease in norepinephrine spillover were significantly higher in heart failure (P<.01 and P=.05, respectively). Thus, although clonidine lowers norepinephrine spillover significantly in patients with heart failure, such patients are less sensitive to clonidine than healthy control subjects. This difference in sensitivity suggests that doses of clonidine provide effective sympathoinhibition will need to be selected for studies that will evaluate the potential therapeutic effect of clonidine in heart failure.

Adrenergic alpha-Agonists↗

Seasonal changes in spermatogenesis and testicular steroidogenesis in the male black bear Ursus americanus.

American black bears, Ursus americanus, are seasonal breeders with a mating season in late spring to early summer. The objectives of this study were to determine whether there are seasonal changes in spermatogenesis and immunolocalization of testicular steroidogenic enzymes, and to correlate these changes with peripheral steroid concentrations. Three captive mature bears were maintained in open cages during the summer season and provided with chambers for denning during the winter. Testicular biopsies and blood samples were obtained from anaesthetized bears on 12 March, 15 June, 12 October and 15 January. Steroidogenic enzymes were immunolocalized using polyclonal antisera raised against bovine adrenal cholesterol side-chain cleavage cytochrome P450 (P450scc), human placental 3 beta-hydroxysteroid dehydrogenase (3 beta HSD), porcine testicular 17 alpha-hydroxylase cytochrome P450 (P450c17) and human placental aromatase cytochrome P450 (P450arom). Spermatogenesis changed seasonally: spermatogonia and degenerating spermatocytes were observed in October; spermatogonia and primary spermatocytes were present in January; spermatogonia, spermatocytes and round spermatids were present in March; and spermatogonia through spermatozoa were present in June. P450scc and P450c17 were immunolocalized in spermatids and Leydig cells in June, whereas in October these enzymes were present only in Leydig cells. 3 beta HSD was localized in Leydig cells in June and October with more intense staining in June. Localization of P450arom changed seasonally: no immunostaining in October; positive immunostaining in Sertoli cells in January; more extensive immunostaining in Sertoli cells, peritubular-myoid cells and round spermatids in March; and strong immunostaining in Sertoli cells and round and elongating spermatids in June. Serum testosterone and oestradiol concentrations changed seasonally: testosterone and oestrogen were low in October and January, slightly higher in March, and high in June. The present study demonstrates that in the black bear seasonal changes in spermatogenesis are accompanied by changes in the immunolocalization of testicular steroidogenic enzymes that are correlated with changes in serum testosterone and oestradiol concentrations. The presence of P450arom in Sertoli cells at the beginning of testicular recrudescence suggests that aromatase and oestrogen may play a role in re-initiating spermatogenesis.

3-Hydroxysteroid Dehydrogenases↗

Comparison of dose regimens for the administration of recombinant pro-urokinase in a canine thrombosis model.

Pro-urokinase represents an important addition to the array of thrombolytic drugs currently available for clinical use because of its high clot specificity but distinctly different mechanism compared with that of t-PA. Recombinant pro-urokinase (r-proUK) is a single-chain precursor of high molecular weight urokinase which has been expressed in a mouse myeloma cell line. The present study was conducted to determine the dosing regimen which would produce optimal clot lysis and restoration of blood flow 2 h after treatment with r-proUK, using a dog model of arterial thrombosis. Efficacy was indicated by lysis of a radio-labelled clot which was formed in the heat-damaged femoral arteries of 39 male beagle dogs. The animals were divided into six heparinized treatment groups, each receiving one of five dosing regimens or the vehicle for r-proUK. The total dose (80,000 U/kg) was divided into an initial loading bolus, followed by either a second bolus or by infusions for various time periods, as shown below: Group Treatment Regimen % Lysis 1 r-proUK Bolus/bolus, 50%/50% at 0 and 15 min 52 +/- 7 2 r-proUK Bolus/bolus, 50%/50% at 0 and 30 min 62 +/- 7 3 r-proUK Bolus/infusion, 20%/80% infused to 30 min 41 +/- 8 4 r-proUK Bolus/infusion, 20%/80% infused to 60 min 66 +/- 5 5 r-proUK Bolus/infusion, 50%/50% infused to 30 min 73 +/- 4 6 Vehicle Bolus/infusion, 50%/50% infused to 30 min 12 +/- 6 It was concluded that optimal clot lysis and restoration of femoral flow was accomplished using a regimen in which 50% of the dose was given as a bolus, followed immediately by the remaining 50% given as a 30 min intravenous infusion (Group 5). At the dose used in this study, r-proUK did not produce degradation of fibrinolytic or hemostatic plasma proteins.

Animals↗

Posterior fossa meningiomas intimately involved with the endolymphatic sac.

Approximately 10% of all intracranial meningiomas occur in the cerebellopontine angle (CPA). Although their clinical presentation depends on their site of origin, most are first seen with nonspecific otologic symptoms like those of acoustic neuroma. We present two cases of CPA meningioma that were intimately involved with the endolymphatic sac and had symptoms and signs suggestive of endolymphatic hydrops.

Cranial Fossa, Posterior↗

Patients with anorexia nervosa demonstrate deficiencies of selected essential fatty acids, compensatory changes in nonessential fatty acids and decreased fluidity of plasma lipids.

The objective of this study was to assess the essential fatty acid status of patients with anorexia nervosa. Blood was collected from eight fasting female anorexia nervosa patients with a mean of 81% ideal body weight. Fatty acid composition of phospholipids, nonesterified fatty acids, triglycerides and cholesteryl esters of plasma were determined by capillary gas chromatography to indicate polyunsaturated fatty acids status compared with 19 healthy female adults < 25 y old. Subjects with anorexia nervosa showed polyunsaturated fatty acid deficiencies in plasma phospholipids different from simple nutritional essential fatty acid deficiency or chronic malnutrition. The phospholipid profile showed significantly lower (n-6) and (n-3) elongation and desaturation products, and elevated short-chain saturated, short-chain monounsaturated, branched-chain and odd-chain fatty acids. These elevations indicate enhancement of biosynthesis of alternative fatty acids that only partially compensated for the loss of polyunsaturated fatty acids in providing membrane "fluidity." Calculated mean melting point of the fatty acids of phospholipids in patients with anorexia nervosa was elevated 7.7 degrees C above normal values. These results demonstrate that patients with anorexia nervosa have deficiencies of selected essential fatty acids, compensatory changes in nonessential fatty acids and decreased fluidity of plasma lipids.

Adolescent↗

The use of r-HuEpo in the treatment of anaemia related to myelodysplasia (MDS).

One hundred and sixteen (116) anaemic patients with myelodysplastic syndromes (MDS) were treated with recombinant human erythropoietin (r-HuEpo) in an open-label, multicentre, compassionate treatment trial; 100 patients received therapy for > or = 4 weeks and were evaluable for efficacy. The distribution of FAB subtypes was: 44 RA, 40 RARS, eight RAEB, two RAEB-t, one CMML, and five not specified. Mean baseline haematocrit was 24.5%, and the mean prestudy transfusion requirement in the 12 weeks immediately prior to study entry was 6.5 units. r-HuEpo treatment was initiated at a dose of 150 U/kg three times weekly, with dose escalations of 50 U/kg monthly (up to 300 U/kg 3x/week) permitted if the haematocrit failed to rise. Response to therapy was defined as either an increase in haematocrit of > or = 6 percentage points over baseline, unrelated to transfusion, or a > or = 50% decrease in transfusion requirement in the last 3 months of study treatment, compared to the baseline period (12 weeks). By these criteria, 28% (28/100) of patients responded to r-HuEpo treatment. Overall, 86% (24/28) of patients responding to therapy had baseline Epo levels < or = 100 mU/ml. Response rates by FAB subtype were: RA 39% (17/44), RARS 17.5% (7/40) and RAEB 12.5% (1/8). Additionally, a 54% (15/28) response rate was seen in RA patients with baseline Epo levels < or = 100 mU/ml. Responses to therapy were durable and generally occurred at r-HuEpo doses of 150-200 U/kg t.i.w. There were no reports of thrombosis, seizures or therapy-related hypertension. The data show that patients with MDS, especially those with the RA and RARS subtypes, can benefit from treatment with r-HuEpo. Those patients with baseline Epo levels < or = 100 mU/ml were most likely to respond to therapy.

Adult↗

Annual changes in serum concentrations of prolactin in captive male black bears (Ursus americanus).

Prolactin may be involved in the regulation of reproduction in black bears (Ursus americanus) as it is a mediator of photoperiodic changes in a number of species. The objectives of this study were to validate a radioimmunoassay to measure prolactin in bear serum and to describe seasonal changes in serum prolactin concentrations in captive male bears. Serum samples were obtained nine times during a year from three captive male black bears that were denning between November and March and active during the other months. The heterologous prolactin radioimmunoassay, using pig 125I-labelled prolactin and goat anti-pig prolactin as a primary antibody, was validated. Injection of thyrotrophin-releasing hormone into the three male bears in June resulted in a rapid increase in serum concentrations of prolactin (t = 0, 11.4-14.8 ng ml-1; t = 15-30 min, 18.4-28.7 ng ml-1). The sensitivity of the assay was 0.08 ng per tube. Intra- and interassay coefficients of variation were 5.5% (n = 6) and 5.7% (n = 6), respectively. Serum concentrations of prolactin changed seasonally, with the lowest concentrations in December (mean +/- SD = 1.1 +/- 0.1 ng ml-1); this was followed by a gradual increase between January (2.6 +/- 0.6 ng ml-1) and April (6.4 +/- 1.2 ng ml-1) and the highest concentrations in May (17.6 +/- 4.7 ng ml-1), preceding peak testosterone concentrations in June. The observation that prolactin secretion increased with increasing daylength suggests that photoperiod may be an external regulator. The presence of high concentrations of prolactin before peak testosterone concentrations suggests that prolactin may play a role in regulating seasonal changes in the testes.

Animals↗

Sensory perceptions of women receiving tamoxifen for breast cancer.

Tamoxifen has been used as adjuvant treatment in advanced and early-stage breast cancer for the past decade. Recently this synthetic antiestrogen drug assumed a new role of chemoprevention for women at risk of developing breast cancer. The commonly occurring side effects associated with tamoxifen administration contribute to the acceptance of this antineoplastic drug for palliation and cure. However, there are no data about the sensory effects of women receiving tamoxifen. The purpose of this study was to elicit subjects' descriptions of sensory experiences while receiving tamoxifen. These descriptions are essential for developing nursing interventions to help patients use self-care behaviors and cope with the side effects of tamoxifen. Sensory data were collected from 20 women who had been receiving tamoxifen for at least 1 month and were not receiving any other chemotherapy. Subjects provided descriptors about all senses. The senses for which subjects most frequently provided descriptors were touch, taste, and sight.

Adaptation, Psychological↗

Loss of appetite: managing unwanted weight loss in the older patient.

Loss of appetite, regardless of cause, is a significant symptom that may cause extreme weight loss in older patients. The consequences of anorexia include muscle wasting, weakness, depression, increased susceptibility to disease complications, and decreased immunocompetence. In the older population, the major causes of anorexia are pulmonary and cardiac diseases, cancer, dementia, alcoholism, depression, and medications. The diagnosis is based on the physical exam, a history of weight loss, and a review of dietary intake. Treatment strategies include managing GI disturbances, encouraging physical activity and socialization, reducing fatigue and food aversions, and adding high-calorie supplements to the diet.

Aged↗