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Biomedical subjects

W D Brown

Publications and source records attributed to W D Brown.

At least 55 records · Page 3Linked to original sources
PubMed1994

Real-time ultrasonography of arterial IVH in preterm infants.

The vascular origin of intraventricular hemorrhage in premature infants is controversial and has been variously attributed to arteries, veins, arterioles, capillaries, or sinusoids that may be found in the vicinity of the ganglionic eminence. The clinical histories and serial ultrasound images are reported from 2 patients with intraventricular hemorrhage of arterial (high pressure) origin that were captured on real-time ultrasonography as they occurred.

Adult↗
PubMed1994

The brain at high altitude: hypometabolism as a defense against chronic hypoxia?

The brain of hypoxia-tolerant vertebrates is known to survive extreme limitations of oxygen in part because of very low rates of energy production and utilization. To assess if similar adaptations may be involved in humans during hypoxia adaptation over generational time, volunteer Quechua natives, indigenous to the high Andes between about 3,700 and 4,900 m altitude, served as subjects in positron emission tomographic measurements of brain regional glucose metabolic rates. Two metabolic states were analyzed: (a) the presumed normal (high altitude-adapted) state monitored as soon as possible after leaving the Andes and (b) the deacclimated state monitored after 3 weeks at low altitudes. Proton nuclear magnetic resonance spectroscopy studies of the Quechua brain found normal spectra, with no indication of any unusual lactate accumulation; in contrast, in hypoxia-tolerant species, a relatively large fraction of the glucose taken up by the brain is released as lactate. Positron emission tomographic measurements of [18F]2-deoxy-2-fluoro-D-glucose (FDG) uptake rates, quantified in 26 regions of the brain, indicated systematically lower region-by-region glucose metabolic rates in Quechuas than in lowlanders. The metabolic reductions were least pronounced in primitive brain structures (e.g., cerebellum) and most pronounced in regions classically associated with higher cortical functions (e.g., frontal cortex). These differences between Quechuas with lifetime exposure to hypobaric hypoxia and lowlanders, which seem to be expressed to some degree in most brain regions examined, may be the result of a defense adaptation against chronic hypoxia.

Adaptation, Physiological↗
PubMed1993

Insomnia. Use of a 'decision tree' to assess and treat.

Insomnia, a remarkably common disturbance in a basic biologic function, arises from multiple psychological, physiologic, and environmental factors. Transient insomnia usually resolves spontaneously. Short-term insomnia is usually normalized by coping with acute changes in a medical condition or a relationship. In patients with insomnia caused by stressful life events, a short (ie, 10 days or less) course of a short- or intermediate-acting benzodiazepine hypnotic may be indicated. Long-term insomnia deserves comprehensive evaluation. Psychiatric disorders are common in patients with long-term insomnia. In patients over age 50, intrinsic sleep disorders are more prevalent. Behavioral therapy, including improved sleep hygiene, stimulus-control techniques, and sleep-restriction therapy, is preferred in the management of long-term insomnia. Pharmacotherapy (eg, low-dose antidepressant or benzodiazepine) is best used as an adjunct.

Decision Trees↗
PubMed1993

Dopaminergic agents in restless legs syndrome and periodic limb movements of sleep: response and complications of extended treatment in 49 cases.

Restless legs syndrome (RLS) is a common neurosensorimotor disorder that presents with paresthesias, sleep disturbances and, in most cases, periodic limb movements of sleep (PLMS). Although many treatments have been described, interest has recently been focused on dopaminergic mechanisms of etiology and treatment. The dopamine agonists L-dopa/carbidopa, bromocriptine mesylate or both were initiated in 49 patients with RLS/PLMS who sought consultation at a sleep disorders center. This retrospective study describes the symptoms, time course of response and complications in 36 men and 13 women with a mean age of 53.9 years. Only 47 of the patients were available for extended follow-up. The most common presenting complaints were the sensation of restless legs and sleep maintenance insomnia lasting over 20 years. In the extended follow-up group of 47, four failed to respond to L-dopa or bromocriptine, five discontinued treatment because of side effects and two reported loss of therapeutic effect within the first month. Between month one and six, only three additional subjects discontinued treatment. At a mean follow-up of 283 days (SD 316), 33 patients continued on L-dopa/carbidopa at a mean bedtime dose of 160 mg L-dopa (SD 300). Treatment-emergent morning leg restlessness developed in eight patients, seven of whom required daytime medication for relief. Other side effects, generally nausea, occurred in only eight of 43 patients. Psychiatric side effects of dyskinesia were not seen. The > 70% long-term response is comparable to other studies in the literature.

Adult↗
PubMed1992

The cortical localization of the lexicons. Positron emission tomography evidence.

Positron emission tomography was used to investigate changes in regional cerebral blood flow (rCBF) in neurologically normal subjects during word reading and word repetition. The blood flow in these conditions was compared with control conditions where subjects were presented with stimuli of comparable auditory and visual complexity to real words and said the same word on presentation of each stimulus. The control condition for word repetition (hearing spoken words presented backwards) resulted in bilateral activation of the superior temporal gyrus. Word repetition caused a significant increase in rCBF over this control condition in the left superior and middle temporal gyri. The control condition for word reading (seeing stimuli written in 'false fonts', i.e. non-existent letter-like forms) resulted in significant changes in rCBF bilaterally in the striate and extrastriate cortex. Word reading caused a significant increase in blood flow relative to this control in the posterior part of the left middle temporal gyrus. The implications of these results are discussed, and it is argued that they are consistent with localization of a lexicon for spoken word recognition in the middle part of the left superior and middle temporal gyri, and a lexicon for written word recognition in the posterior part of the left middle temporal gyrus.

Adult↗
PubMed1992

Evaluation of cefuroxime axetil and cefadroxil suspensions for treatment of pediatric skin infections.

A randomized, single-blind, multicenter study was conducted to evaluate the safety and efficacy of cefuroxime axetil and cefadroxil suspensions for the treatment of skin or skin structure infections in 287 children. Each drug was given at a dosage of 30 mg/kg of body weight per day in two divided doses. Staphylococcus aureus and Streptococcus pyogenes, or a combination of the two, were the primary pathogens isolated from infected skin lesions. A satisfactory bacteriological response (cure or presumed cure) was obtained in 97.1 and 94.3% of children in the cefuroxime axetil and cefadroxil groups, respectively (P greater than 0.05). Satisfactory clinical responses (cure or improvement) were more likely to occur in cefuroxime axetil recipients than in cefadroxil recipients (97.8 versus 90.3%; P less than 0.05). Both regimens were equally well tolerated, with adverse events occurring in 7.9 and 6.1% of cefuroxime axetil and cefadroxil recipients, respectively. There were more patients who refused to take cefuroxime axetil (7 of 189) than there were who refused to take cefadroxil (0 of 98), but the difference was not statistically significant (P = 0.1). In this study, cefuroxime axetil was at least as effective as cefadroxil in resolving skin and skin structure infections in children.

Cefadroxil↗
PubMed1992

Incorrect use of metered dose inhalers by medical personnel.

We administered a questionnaire and observed usage of a placebo metered dose inhaler (MDI) among 35 physicians, 14 nurses, and 12 respiratory therapists. Ninety-two percent of the respiratory therapists performed at least four of seven steps correctly, compared with 65 percent of house staff physicians, 57 percent of nurses, and 50 percent of nonpulmonary faculty. Most participants followed package insert instructions, while only 18 percent followed recent recommendations for proper MDI use. We conclude that (1) medical personnel should have additional instruction in proper MDI usage and (2) respiratory therapists and nurses can play a prominent role in instructing patients in their proper use.

Allied Health Personnel↗
PubMed1991

Cortical and subcortical localization of response to pain in man using positron emission tomography.

A quantitative study of the regional cerebral responses to non-painful and painful thermal stimuli in six normal volunteers has been done by monitoring serial measurements of regional blood flow measured by positron emission tomography (PET). In comparison to a baseline of warm stimulation no statistically significant changes in blood flow were seen in relation to increasing non-painful heat. However, highly significant increases in blood flow were seen in response to painful heat in comparison to non-painful heat. These changes were in the contralateral cingulate cortex, thalamus and lenticular nucleus. These findings are discussed in relation to previous physiological observations of responses to nociceptive stimuli in man and primates.

Adult↗
PubMed1991

Cerebral blood flow and metabolism studies in multi-infarct dementia.

In the last 40 years, blood flow and metabolism in the brain have been measured by many methods of varying resolution and reliability. Modern methods have helped to answer some basic pathophysiologic questions, in particular disproving ongoing global ischemia as a cause for dementia. But much of this physiologic work is confounded by swiftly changing clinical and pathologic understandings of ischemic and other forms of dementia: the field remains limited as much by unresolved clinical questions as by technologic feasibility.

Aged↗
PubMed1990

Prevalence of hypercholesterolemia in a maritime population.

The problem of hypercholesterolemia is of growing concern and public awareness. The cholesterol determinations of 567 maritime personnel, dependent upon a shipboard diet for a major portion of the year, were reviewed. Total cholesterol levels were borderline in 32.7% and high in 28.2% of the population, using definitions of the National Cholesterol Education Program. There was an age-related increase in average total cholesterol levels. The levels of low-density lipoprotein cholesterol and high-density lipoprotein cholesterol in this population are also reported where available. The opportunities for intervention in this population are unique, as are the potential impediments to intervention.

Adult↗
PubMed1989

Spontaneously reduced testicular torsion. A pitfall in radionuclide scrotal imaging.

The radionuclide scrotal scan is highly accurate in the differential diagnosis of acute torsion vs epididymo-orchitis. While the scan findings of increased flow through the spermatic cord and increased static scan activity suggest inflammation, its appearance is not always diagnostic of inflammatory disorder. That this may also occur after reduction of torsion has not been emphasized in the literature. A case report of spontaneous reduction of testicular torsion is presented which demonstrates both increased flow and increased static image activity mimicking epididymitis.

Adult↗
PubMed1989

How to select patients with deep vein thrombosis for tPA therapy.

Despite enthusiasm for using thrombolytic therapy to treat proximal deep venous thrombosis (DVT), the proportion of patients eligible for this therapeutic strategy is unknown. Therefore, we screened all patients at Brigham and Women's Hospital who underwent leg venography in 1987. Of 240 patients with suspected DVT, 87 (36%) had positive venograms. Of those with positive venograms, 72 (83%) had proximal DVT, and 15 (17%) had DVT limited to calf veins. Overall, 22% of patients with proximal DVT were eligible for thrombolytic therapy. The major exclusion criteria were: (1) recent trauma or surgery, (2) recent GI bleeding, and (3) history of a bleeding disorder. Thus, thrombolytic therapy could be given to approximately one-fifth of our patients with proximal DVT.

Adult↗
PubMed1988

Effects of short duration exposures to acetone and methyl ethyl ketone.

Workers are commonly exposed to mixtures or combinations of chemical agents, and these mixtures often consist of solvents. One group of solvents that has been extensively studied for its neurotoxic properties has been the ketones. However, previous research has focused on neuropathies produced by extended exposures and not on the simple pharmacokinetics or the reversible central nervous system (CNS) effects from short-duration exposures. In this research, 137 volunteers were recruited and tested for neurobehavioral performance changes and biochemical indicators during and after a short-duration (4-h) exposure to either acetone at 250 ppm, methyl ethyl ketone (MEK) at 200 ppm, acetone at 125 ppm with MEK at 100 ppm, or a chemical-placebo. Ethanol (95%, 0.84 ml/kg) was used as a positive control. Testing took place in an environmental chamber with four test stations. The computer-controlled test regimen took 10 h, and several measures were collected: (1) biochemical measurements of venous blood and alveolar breath; (2) psychomotor tests of choice reaction time, visual vigilance, dual task (auditory tone discrimination and tracking), and memory scanning; (3) one sensorimotor (postural sway) test; and (4) one psychological (Profile of Mood States [POMS]) test. Blood and breath concentrations during and after exposure did not demonstrate any interaction between the two solvents, nor were statistically significant sex differences present during uptake or elimination. The 250-ppm acetone exposure produced small but statistically significant differences from controls in two measures of the auditory tone discrimination task, and on the anger-hostility scale (males only) of the POMS test. The other chemical exposure conditions, MEK at 200 ppm and combination MEK with acetone, produced no consistent statistically significant results, which suggests there was no potentiation of the acetone effects with the co-exposure to MEK or vice versa under these test conditions. Ethanol at 0.07-0.08% blood alcohol concentration (BAC) caused significant decrements on both the auditory tone and tracking tests in the dual task.

Acetone↗
PubMed1988

Aortic regurgitation and mitral valve prolapse with Down's syndrome: a case-control study.

This case-control study was designed to determine whether aortic regurgitation (AR) and mitral valve prolapse (MVP) are specifically associated with Down's syndrome, or occur in a comparably retarded population without Down's syndrome. The 92 control subjects resided at the same institution as the 131 cases, and had mental retardation attributable to low birth weight or perinatal asphyxia. Mean (+/- SD) ages of the cases and the control group were 41 +/- 11 years compared with 40 +/- 13 years, respectively. The relative risk of AR among the cases (those with Down's syndrome) was 2.9 (95% confidence interval, 0.65-13.2; P = 0.16) and that of MVP was 3.5 (95% confidence interval, 1.2-10.2; P = 0.02). The results showed that these two valvular abnormalities are specifically associated with Down's syndrome in adults.

Adult↗
PubMed1988

A microcomputer-assisted exercise prescription for use by family physicians.

Family physicians frequently advise their patients on choosing and implementing regular programs of exercise. This report describes techniques of submaximal aerobic fitness assessment and microcomputer-assisted exercise prescription suitable for use in office-based practice. A submaximal bench step test is used for the estimation of aerobic fitness. A BASIC program operating on a Macintosh provides calculations of fitness levels and produces an individualized exercise prescription. While obviously not suitable for every patient, this approach is practical for young to middle-aged low-risk individuals interested in beginning regular training programs.

Adult↗
PubMed1987

High frequency of mitral valve prolapse and aortic regurgitation among asymptomatic adults with Down's syndrome.

Although cardiac anomalies are well documented among children with Down's syndrome, data on the cardiac status of adults with Down's syndrome are sparse. Therefore, we performed cardiac auscultation and Doppler echocardiographic examinations in 35 asymptomatic adults with Down's syndrome. There were 25 men and ten women; their mean age (+/- SD) was 26 +/- 8 years. Only ten subjects (29%) had normal findings on examination. The most frequent abnormal findings were holosystolic mitral valve prolapse (MVP) in 20 subjects (57%) and mild aortic regurgitation in four subjects (11%). Of the 20 subjects with MVP, five had associated tricuspid valve prolapse, but none had notable mitral regurgitation. Thus, we found that the majority of asymptomatic adults with Down's syndrome had valvular heart abnormalities. The high frequency of MVP and aortic regurgitation suggests that these lesions may be specifically associated with Down's syndrome in adults.

Adult↗