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Biomedical subjects

G Brown

Publications and source records attributed to G Brown.

At least 505 records · Page 28Linked to original sources
PubMedDate not supplied

Pattern-onset visual evoked potentials: more useful than reversal for patients with nystagmus.

PURPOSE: The visual evoked potential is often used to assess visual function in neurologically impaired patients, a group in whom nystagmus is a common feature. Pattern-reversal stimuli are commonly used to produce visual evoked potentials in clinical practice. Previous reports have shown that this stimulus is not optimal when subjects have nystagmus. The present study aimed to compare the efficacy of pattern-onset and reversal stimuli when used to measure visual evoked potentials from subjects with idiopathic nystagmus. METHODS: In five adults with congenital nystagmus and 10 visually normal adults, VEPs were recorded and reproduced for checkerboard stimuli of two sizes (120' and 60'). Each size was presented as both pattern-onset and reversal check. RESULTS: Visually normal adults demonstrated similar visual evoked potential amplitudes and quality in response to pattern-reversal and pattern-onset. However, in the presence of nystagmus, visual evoked potentials recorded to pattern-reversal stimuli were significantly smaller and of poorer quality than those obtained to pattern-onset stimuli (analysis of variance p<0.05; Kendall's tau, p<0.05). CONCLUSIONS: Pattern-onset stimuli produce larger and clearer visual evoked potentials in patients with nystagmus compared with those produced to pattern-reversal stimuli.

Adult↗
PubMedDate not supplied

Nodal staging in rectal cancer.

Rectal cancer is common and nodal disease is an independent adverse prognostic factor for patient survival. Accurate demonstration of the presence and location of nodal disease preoperatively may influence management strategies. In this article we review the pathways of nodal spread in rectal cancer and assessment of nodal disease using sonography, CT, and MRI. The use of morphological criteria instead of size criteria has been shown to improve nodal staging by MRI. The potential role of magnetic resonance lymphography and PET imaging in further improving nodal staging accuracy is discussed.

Contrast Media↗
PubMedDate not supplied

In vivo characterization of the putative 5-HT1A receptor antagonist SDZ 216,525 using two models of somatodendritic 5-HT1A receptor function.

SDZ 216,525 has been proposed to be a silent 5-HT1A receptor antagonist. The present study examined the potential intrinsic agonist action of SDZ 216,525 using two in vivo models of somatodendritic 5-HT1A autoreceptor function: 5-HT release using microdialysis and feeding behaviour of satiated animals. SDZ 216,525 (1 mg/kg s.c.) and the alpha 1-adrenoceptor antagonist prazosin (1 mg/kg s.c.) significantly decreased hippocampal 5-HT release. In addition, SDZ 216,525 (3 and 10 mg/kg s.c.) and prazosin (3 and 10 mg/kg s.c.) significantly increased food intake in satiated rats. The selective 5-HT1A receptor antagonist (RS)-WAY100135 (10 mg/kg s.c.) which has been demonstrated to block the effects of 8-OH-DPAT on 5-HT release and food intake had no significant effect on the response induced by SDZ 216,525. In contrast, the non-selective 5-HT1A receptor antagonist (-)-pindolol (8 mg/kg s.c.) attenuated both SDZ 216,525 responses. The decrease in hippocampal 5-HT release and increase in food intake induced by SDZ 216,525 suggest that the compound may be a 5-HT1A receptor partial agonist. However, the failure of the 5-HT1A receptor antagonist (RS)-WAY100135 to block the SDZ 216,525 responses suggests that SDZ 216,525 decreases 5-HT release and increases food intake by a mechanism other than 5-HT1A receptor agonism. The high affinity of SDZ 216,525 for the alpha 1-adrenoceptor, and the ability of prazosin to decrease 5-HT release and increase food intake, suggest that the effects of SDZ 216,525 may be mediated via an alpha 1-adrenoceptor antagonist action.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMedDate not supplied

Acetaminophen-induced hypotension.

Through 30 years of widespread use, acetaminophen has been shown to be a remarkably safe medication in therapeutic dosages. The potential for acetaminophen to produce cardiovascular toxicities is very low. However, acetaminophen has been demonstrated to produce symptoms of anaphylaxis, including hypotension, in sensitive individuals. This article describes two critically ill patients in whom transient episodes of hypotension reproducibly developed after administration of acetaminophen. Other symptoms of allergic reactions were not clinically detectable. The hypotensive episodes were severe enough to require vasopressor administration. The reports illustrate the need for clinicians to consider acetaminophen in patients with hypotension of unknown origin.

Acetaminophen↗
PubMedDate not supplied

A neuroendocrine study of serotonin function in depressed stroke patients compared to non depressed stroke patients and healthy controls.

OBJECTIVES: We employed a neuroendocrine challenge paradigm to study serotonergic abnormalities associated with poststroke depression. METHOD: Twelve depressed stroke patients (major depression N= 5, minor depression N = 7), 8 nondepressed stroke patients and 12 healthy volunteers completed a single-blind, placebo-controlled, challenge tests. Baseline cortisol (CORT) and prolactin (PRL) values, and these hormonal responses to 30 mg of oral d-FEN and placebo over a 4 hour period were measured in the three groups. RESULTS: There were intergroup differences for baseline adjusted PRL responses (change scores from baseline) to d-FEN (group effect F = 4.38, df = 2,29, p = 0.02) while these responses to placebo were comparable between groups (group effect F = 1.82, df = 2,29, p = 0.18). Peak PRL responses (post d-FEN maximal PRL change from baseline scores) in depressed stroke patients were significantly greater than in nondepressed patients (p = 0.005) but comparable to healthy normals (p = 0.47). However, these responses between major and minor depression were not significant (p = 0.34). There was a trend suggesting a negative correlation between peak PRL response and severity of depression (p = 0.056). Depressed patients were younger than the controls (p = 0.054). Also, the depressed group was more functionally impaired (p = 0.04) and more likely to have right-sided lesions (p = 0.009) compared with the nondepressed group. Differences in baseline adjusted PRL changes between depressed and nondepressed groups became non significant when the influence of laterality of lesions was covaried, whereas covariation of functional scores and age did not alter the significance. CORT responses did not show intergroup differences. LIMITATIONS: The study group was small and was heterogenous in lesion characteristics, time since stroke and type of depression. A fixed-order design was used in the challenge test paradigm. CONCLUSIONS: When laterality of stroke lesion was taken into account, depressed and nondepressed stroke patients did not differ in PRL responses to d-FEN.

Aged↗
PubMedDate not supplied

Ceftriaxone versus cefazolin with probenecid for severe skin and soft tissue infections.

To evaluate the hypothesis that a single daily administration of cefazolin and probenecid and a single daily administration of ceftriaxone and probenecid would be equally effective, in combination with oral antibiotics, for the outpatient treatment of skin and soft tissue infections, a randomized, double-blind study was completed. Patients presenting to the Emergency Department with the primary diagnosis of cellulitis or soft tissue infection, excluding patients requiring immediate hospital admission, received either 2 g of ceftriaxone or 2 g of cefazolin, each with 1 g of probenecid, on a daily basis as outpatients from the Emergency Department. The patients were given a prescription for oral penicillin and cloxacillin for independent procurement. Outcome was assessed based on reduction in the size of the infected area, and the need for additional treatment (other antibiotics or hospital admission). A total of 194 patients were randomized to receive ceftriaxone (96) or cefazolin (98). There was no statistical difference in cause of infection, site of infection, duration of treatment, noncompliance or need for incision or drainage of the wound. The outcome, as determined by the ratio of the involved infected area on initial and last treatment day, and the frequency of failure were similar. The single daily administration of 2 g of either cefazolin, in combination with probenecid, or ceftriaxone are equivalent in efficacy in the outpatient treatment of skin and soft tissue infections. There is the potential for significant cost savings in utilizing outpatient cefazolin therapy over ceftriaxone for treatment of these infections.

Ambulatory Care↗
PubMedDate not supplied

Receptor demise from alteration of glycosylation site in Drosophila opsin: electrophysiology, microspectrophotometry, and electron microscopy.

In the delta Asn20 Drosophila stock, the N-linked glycosylation site of opsin in R1-6 receptors (Rh1) is absent. We used electroretinography (ERG), microspectrophotometry (MSP), and electron microscopy (EM) to quantify visual cell defects. Positive controls, w9, had wild type Rh1. MSP revealed minimal photopigment in delta Asn20 for 6 days posteclosion; w9 had near normal visual pigment. ERG sensitivity and prolonged depolarizing afterpotential (PDA) were compared for delta Asn20 and w9. Delta Asn20's R1-6 function is decreased 100-fold at eclosion and diminishes until only R7/8 functions at 11 days. What little rhodopsin is routed to the rhabdomere functions. Morphometry showed smaller R1-6 rhabdomeres in delta Asn20 for 8 days posteclosion. Rhabdomeres in w9 were normal. A negative control, ninaE(ol17), a deletion of the Rh1 gene, also has small rhabdomeres. Delta Asn20 and ninaE(ol17) lack the extreme rhabdomere elimination of ora (outer rhabdomeres absent), a nonsense mutant interrupting Rh1's coding sequence. Delta Asn20 and ora have surplus membrane while ninaE(ol17) does not. Freeze fracture reveals that delta Asn20's rhabdomeric P-face particle count is as low as for vitamin A deprivation, consistent with an opsin defect. High particle density, organized into rows, is present in adjacent plasmalemma where surplus membrane accumulates. In summary, delta Asn20 interferes with either synthesis, deployment, or maintenance of opsin.

Animals↗
PubMedDate not supplied

Changes in analogical reasoning in adulthood.

This study sought to investigate adult intellectual development through an analysis of a particular type of cognitive ability, verbal analogical reasoning. The performance of 60 individuals between the ages of 20 and 79 was compared on 100 verbal analogies. The subjects consisted of six groups of ten individuals each (five males and five females), matched as a group for education and gender. Solution times and error rates served as the dependent measures. Results showed that there was a significant trend for the older subjects (60- and 70-year-olds) to be slower than the young subjects (20-, 30-, 40-, and 50-year-olds), but not necessarily more error prone. These data suggest that verbal analogical reasoning changes with age. Supplemental data demonstrated a change in other abilities as well (i.e., decline in perceptual-motor speed and spatial skill).

Adult↗
PubMedDate not supplied

EMS agenda for the future: Virginia providers' perspectives.

OBJECTIVE: Revolutionary changes in the health care system necessitate subsequent changes in emergency medical services (EMS). The development and dissemination of the EMS Agenda for the Future focus attention on awareness and attitudes of field providers. This study attempted to measure awareness of and agreement with concepts set forth in the agenda. METHODS: Through a unique cooperative partnership between state government and two health services research students, researchers were able to describe and explore the attitudes of EMS providers about the future direction of the profession. A representative sample of participants, chosen from the Commonwealth of Virginia in fall 1997, responded to a mailed researcher-developed questionnaire based on the EMS Agenda for the Future. RESULTS: A cover letter written by the state EMS director and the enclosure of self-addressed, stamped envelopes yielded a 47% response rate. Paramedic-level providers and paid personnel were more likely to agree with the concepts of the EMS Agenda for the Future than were other-level providers and volunteers. The attribute with which the respondents agreed most was "legislation and regulation." The respondents agreed the least with "integration of health services." Providers were most concerned with the issue of liability protection, one aspect of the "legislation and regulation" attribute. Only 10% of the respondents reported having read the agenda. CONCLUSIONS: EMS providers' awareness, perspectives, and attitudes are essential to the forward progression of the EMS Agenda for the Future. Successful implementation of the agenda will depend on these professionals' participation and support. Providers tended to agree most with traditional concepts discussed in the EMS Agenda for the Future. Awareness levels and attitudes toward the vision suggest implications for future education, planning, and research activities.

Adolescent↗
PubMedDate not supplied

The use of muscle stimulation for inducing scoliotic curves. A preliminary report.

Based on a clarification of the anatomical mechanisms involved in the lateral stability of the spine, electrical stimulation was applied unilaterally to paraspinal muscles of 20 growing dogs in an attempt to produce thoracic scoliotic curves. These experiments were considered critical in the development of a new procedure for correcting human scoliosis. Various alternating voltages and wave forms were used. The curvature varied with the voltage applied, frequency being maintained at a constant value. Curves can be developed in the spines of normal dogs by unilateral electronic muscle stimulation without clinical discomfort or significant muscle atrophy. Curves always develop in the predicted direction (concave to stimulation). Stimulation of more than 4-6 weeks produced curves with significant wedging and rotational deformation. In one experiment curves created in one direction were reversed by stimulating opposite side musculature. Because of the similarity of human and canine anatomy, the results obtained gave impetus to further experimentation with human application. Electromyographic tests, biopsy studies, direct deformation measurements of post mortem dissections and weekly X-rays substantiate the above observations.

Animals↗
PubMedDate not supplied

A randomized, double-blind, placebo-controlled crossover study of the effect of exogenous melatonin on delayed sleep phase syndrome.

OBJECTIVE: The effects of exogenous melatonin on sleep, daytime sleepiness, fatigue, and alertness were investigated in 22 patients with delayed sleep phase syndrome whose nocturnal sleep was restricted to the interval from 24:00 to 08:00 hours. This study was a randomized, double-blind, placebo-controlled crossover trial. Subjects received either placebo or melatonin (5 mg) daily for 4 weeks, underwent a 1-week washout period, and then were given the other treatment for an additional 4 weeks. Patients could take the melatonin between 19:00 and 21:00 hours, which allowed them to select the time they felt to be most beneficial for the phase-setting effects of the medication. METHODS: Two consecutive overnight polysomnographic recordings were performed on three occasions: at baseline (before treatment), after 4 weeks of melatonin treatment, and after 4 weeks of placebo treatment. RESULTS: In the 20 patients who completed the study, sleep onset latency was significantly reduced while subjects were taking melatonin as compared with both placebo and baseline. There was no evidence that melatonin altered total sleep time (as compared with baseline total sleep time), but there was a significant decrease in total sleep time while patients were taking placebo. Melatonin did not result in altered scores on subjective measures of sleepiness, fatigue, and alertness, which were administered at different times of the day. After an imposed conventional sleep period (from 24:00 to 08:00), subjects taking melatonin reported being less sleepy and fatigued than they did while taking placebo. CONCLUSIONS: Melatonin ameliorated some symptoms of delayed sleep phase syndrome, as confirmed by both objective and subjective measures. No adverse effects of melatonin were noted during the 4-week treatment period.

Adult↗
PubMedDate not supplied

Influence of cations on kinetics of angiotensin II binding to adrenal, renal, and smooth muscle receptors.

A number of biological responses to angiotensin II have been demonstrated to be modulated acutely by cations, but the exact mechanism has not been elucidated. We have utilized a radioreceptor assay for angiotensin II to determine whether this acute regulatory mechanism could be related to a change in either number or affinity of angiotensin II binding to receptors. Three target tissues were used (adrenal glomerulosa, glomeruli, and uterine smooth muscle). Both mono- and divalent cations influence the kinetics of angiotensin II binding in a similar manner in all tissues. Divalent cations increase the number of receptor sites to a greater extent than did monovalent cations, while monovalent cations changed binding affinity to a greater extent than did divalent cations. These studies demonstrate that both the number and affinity to a greater extent than did monovalent cations, while monovalent cations changed binding affinity to a greater extent than did divalent cations. These studies demonstrate that both the number and affinity of angiotensin receptors can be rapidly modulated by a variety of cations.

Adrenal Glands↗
PubMedDate not supplied

RCN nursing update with BBC learning zone.

RCN Nursing Update brings the classroom direct to the student. It consists of a series of television programmes on BBC2's Learning Zone and complementary booklets published with Nursing Standard. This report describes how the project has developed and notifies students of the forthcoming changes in programme schedules and accompanying booklets.

Computer-Assisted Instruction↗
PubMedDate not supplied

Technology in nurse education: a communication teaching strategy.

This article focuses on the topic of technology in nurse education as a communication learning tool. Nurses are very interested in learning more about telehealth through the application of technology--computer-managed instruction (CMI), computer adaptive testing (CAT), computer stimulation testing (CST), telenursing, telemedicine and the Internet as it relates to improving health care delivery. With the current technology, there are many clinical implications, faculty concerns, and student issues in documentation and the explosion of knowledge and research as a direct source of information. This technology may also serve as a catalyst in bringing positive changes in the practice and the profession of nursing in collaboration with other health disciplines. Although there are limitations that cost may be a major deterrent in some schools of nursing, it is a fact that technology has invaded today's health care delivery system and the society, and is here to stay.

Communication↗