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Biomedical subjects

W Bradley

Publications and source records attributed to W Bradley.

At least 19 recordsLinked to original sources
PubMed1990

Stroke in young adults.

Strokes in young adults are uncommon and often a diagnostic challenge. A retrospective study of strokes due to intracerebral hemorrhage, subarachnoid hemorrhage, or cerebral infarction was undertaken. We reviewed the medical records of 113 young patients aged 15-45 years who were admitted to the Medical Center Hospital of Vermont with a diagnosis of stroke between 1982 and 1987. This group comprised 8.5% of patients of all ages admitted for stroke, 2.3 times the proportion observed in the National Survey of Stroke. Nontraumatic intracerebral hemorrhage was diagnosed in 46 young patients (41%); the main causes included aneurysms, arteriovenous malformations, hypertension, and tumors. Subarachnoid hemorrhage was found in 19 young patients (17%); the majority were due to aneurysms. The remaining 48 young patients (42%) had cerebral infarction, the majority due to cardiogenic emboli and premature atherosclerosis. Mitral valve prolapse, the use of oral contraceptives, alcohol drinking, and migraine were infrequent sole causes of cerebral infarction in the absence of other risk factors. The case-fatality rate for this group of young patients with stroke was 20.4% compared with 23.9% for the National Survey of Stroke. Young adults with stroke deserve an extensive but tailored evaluation, which should include angiography and echocardiography.

Adolescent↗
PubMed1987

Noninvasive quantification of left ventricular myocardial mass by gated proton nuclear magnetic resonance imaging.

The validity of cardiac nuclear magnetic resonance imaging for determination of left ventricular myocardial mass was evaluated in nine dogs. A gated spin echo-pulsing sequence was used for in vivo imaging, obtaining 0.7 cm thick slices of the heart spaced by 1 cm. On each imaged slice, the left ventricular surface area was reproducibly determined by planimetry and was multiplied by slice spacing and specific gravity of the myocardium (1.05) to obtain slice mass. Total left ventricular mass was calculated by adding slice masses in short-axis (method I), transaxial (method II) and vertical long-axis (method III) orientations using Simpson's rule. With each method, masses of the portions of the left ventricle subject to partial volume effect either were not accounted for or alternatively were estimated from the same or an orthogonal imaging plane. Calculated left ventricular mass was compared with the actual excised left ventricular weight. With NMR imaging of in situ nonbeating hearts, best results were obtained when either method I or method II was used and partial volume effect was estimated either from the same or an orthogonal plane. With in vivo NMR imaging, best results were noted when method I was used and mass of the partial volume apex was calculated from transaxial slices: Y (in vivo NMR image) = 8.3 + 0.99X, r = 0.996, SEE = 3.14. For this method, the interobserver reliability coefficient and standard error of the measurement were 0.97 and 5.4, respectively. Compared with method I, in vivo methods II and III were associated with larger errors (SEE ranging from 13.03 to 19.03) regardless of the approach used to estimate partial volume effect. It is concluded that NMR imaging is a highly accurate noninvasive method for in vivo measurement of left ventricular mass in dogs and offers promise for accurate measurement of left ventricular mass in patients.

Animals↗
PubMed1986

Magnetic resonance imaging in intractable partial epilepsy: correlative studies.

A study was performed evaluating magnetic resonance imaging (MRI) in 35 patients with intractable complex partial seizures in whom computed tomographic (CT) scans showed no focal abnormalities. These results were correlated with positron emission tomography evaluation (PET), the electroencephalographic ictal onset, and findings during pathological examination. Seven patients had structural lesions that were epileptogenic, detected by MRI; the lesions were tuberous sclerosis, astrocytomas, or hamartomas. Three of these 7 patients underwent PET scanning, which was normal in all. Of 18 patients with mesial temporal sclerosis, 10 were shown by PET to have temporal lobe hypometabolism, though all 18 had normal MRI findings. The results indicate that MRI contributes information to that provided by CT and PET, by detecting nonsclerotic epileptogenic lesions of the temporal lobe.

Astrocytoma↗
PubMed1983

Technique to maintain separation of mandibular loops in interstitial implantation of head and neck tumors.

Cancers of the floor of the mouth and lower gingiva are treated by an approach combining external radiation treatment and interstitial implant with Iridium-192 radioisotopes. One technique to administer the dose to these areas is a "loop" technique. A major problem in edentulous patients is that the plastic loops housing the Iridium-192 sources slide out of place along the gum, resulting in loss of ideal spacing. When this occurs, dosimetry for the implant generated from localization films prior to loading does not reflect the distribution of dose delivered. To overcome this problem, we have devised polytetrafluoroethylene (PTFE) spacers which, when used between the loops, maintains their correct spacing. An implant technique and the spacers will be described.

Brachytherapy↗
PubMed1980

The neuropathy of abetalipoproteinemia.

The clinical, electrophysiologic, and pathologic features of the peripheral neuropathy in abetalipoproteinemia (Bassen-Kornzweig disease) have been described incompletely. On the basis of findings in threee patients, we believe that large muscle fibers in peripheral nerves are selectively affected and that weakness may be due to chronic partial denervation.

Abetalipoproteinemia↗
PubMed1979

Corneal response to thick and thin hydrophilic lenses.

Thick and thin hydrophilic lenses with otherwise similar parameters were worn by patients for a period of 6 months. The thicker lenses produced greater changes in corneal sensitivity and thickness during the course of adaptation and wear than did the thinner lenses. Chronic edema levels of 3--4% were noted with the thick lenses. Changes in corneal power for each lens group were not significant. Thin hydrophilic lenses seemed to produce less upset of normal corneal physiology over the course of the 6-month wearing period.

Contact Lenses, Hydrophilic↗
PubMed1977

Evaluation of research needs in nephrology in urology. Obstructive and neuromuscular disorders affecting the urinary system.

Obstructive and neuromuscular disorders are common problems of the urinary tract. They cause considerable morbidity and some mortality. In all problem areas research efforts have been and continue to be limited. The principal reason for the lack of research efforts in these areas is the lack of trained established investigators interested in the problems of the urinary tract. Unfortunately, most basic scientists with the research and investigative background to solve many of these problems see them as mundane and not worthy of investigation. In addition, these same basic scientists are out of touch with clinical urologic diseases and probably do not appreciate the magnitude of the problems. In our opinion the solution is 2-fold: to train qualified investigators in urology and nephrology, and to interest, educate and collaborate with the basic scientists about these clinical problems of the urinary tract.

Action Potentials↗