Biomedical subjects
Publications and source records attributed to W Cohen.
A judicial hanging occurred in the state of Washington. Neck injuries were studied by MRI (Magnetic Resonance Imaging) and CT (Computed Tomography). In addition, vertebral arteriograms were performed to evaluate the nature of the neck injury. This report details the anatomical changes produced by judicial hanging.
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Physicians, carefully adhering to the definitions of Physicians' Current Procedural Terminology (CPT) billing codes, used the same CPT codes to denote evaluation and management services that varied widely in work and used different codes for services whose work was the same. As payment shifted to the Medicare Fee Schedule, it was important that the coding system be redefined so that codes consistently reflect the resource costs of these services. Redefining these codes for a resource-based payment system required an understanding of how verifiable predictors relate to physician work. Using data obtained from the Resource-Based Relative Value Scale (RBRVS) study regarding 377 services surveyed among physicians in 31 specialties, multiple regression analyses of the relationship of different variables to the mean values of work were performed. Intraservice time, which accounted for 90% of the variance, was the most important predictor of intraservice work. Specification of time, which previously had not been an element in the definitions of CPT codes for evaluation and management services, was useful in refining these codes so that their value corresponds more closely to resource costs. Other predictors of work were site of service or visit type, patient status (new/initial, established/subsequent), and referral status (consultation, nonconsultation).
The case is presented of a young woman with acute cauda equina syndrome from a ruptured aneurysm in the sacral canal. The lesion was associated with pathological enlargement of the lateral sacral arteries bilaterally, which presumably occurred to provide cross-pelvic collateral flow in response to the diversion of the right internal iliac artery for renal transplantation. The patient presented with signs and symptoms of spontaneous spinal epidural hemorrhage. The radiographic features of this lesion are described. In addition to angiography and partial embolization of the vascular supply, contrast-enhanced high-resolution computerized tomography was essential in the diagnosis and treatment of this unique aneurysm.
To characterize neurological and neuropsychological findings associated with human immunodeficiency virus type-I (HIV) infection, 77 seropositive homosexual or bisexual males with no or minor symptoms of HIV were compared prospectively to 44 HIV seronegative men by observers blinded to serological status of the subjects. Neurological symptoms and examination findings were not significantly different between seropositives and seronegatives except for cranial nerve findings, predominantly mild hearing impairment. Mean performance scores for a 15-test neuropsychological battery were within an unimpaired range for both groups, although for five tests, mean scores were significantly poorer in seropositives. After adjustment for vocabulary score, and demographic and psychosocial variables, the mean score of seropositives was significantly worse only for the Benton Visual Retention Test. Magnetic resonance (MR) images of brain were abnormal in 14 (27%) of 52 seropositives and one of 10 seronegatives (value was not significant). HIV was isolated from cerebrospinal fluid (CSF) in 31 (61%) of 51 seropositives. The only clinical or laboratory difference between CSF culture positives and negatives was a higher CSF immunoglobulin synthesis rate in the former subjects (medians of 10.3 versus 0.1 mg/day; p = 0.03). An additional 13 seropositive subjects had immunologic evidence of central nervous system HIV infection, defined by a serum-to-CSF HIV antibody ratio of less than 5.5. Intracranial abnormalities on MR imaging were associated with CSF immunologic responses to HIV. Nervous system involvement occurred in the vast majority of men with early HIV infection, but clinically significant impairment was uncommon.
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The effects of perceptual organization on hemispheric visual-information processing were assessed with stimulus arrays composed of short lines arranged in columns. A visual-search task was employed in which subjects judged whether all the lines were vertical (same) or whether a single horizontal line was present (different). Stimulus-display organization was manipulated in two experiments by variation of line density, linear organization, and array size. In general, left-visual-field/right-hemisphere presentations demonstrated more rapid and accurate responses when the display was perceived as a whole. Right-visual-field/left-hemisphere superiorities were observed when the display organization coerced assessment of individual array elements because the physical qualities of the stimulus did not effect a gestalt whole. Response times increased somewhat with increases in array size, although these effects interacted with other stimulus variables. Error rates tended to follow the reaction-time patterns. The results suggest that laterality differences in visual search are governed by stimulus properties which contribute to, or inhibit, the perception of a display as a gestalt. The implications of these findings for theoretical interpretations of hemispheric specialization are discussed.
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PURPOSE: This study was designed to measure response rates and survival in patients with acquired immunodeficiency syndrome (AIDS) and suspected Toxoplasma encephalitis treated empirically and in AIDS patients treated for biopsy-proven toxoplasmosis. PATIENTS AND METHODS: AIDS patients identified at Bellevue Hospital between August 1985 and May 1986, who had abnormal computed tomographic scans of the brain and who received empiric treatment for toxoplasmosis, constitute the empirically treated cohort. A cohort with biopsy-proven toxoplasmosis was identified from Bellevue Hospital neuropathology records spanning 1981 through 1986. Patient records were reviewed with a standardized data form, and tomograms were evaluated by neuroradiologists unaware of the identity of the scans. Survival analysis was performed by the product limit method. RESULTS: Of 38 empirically treated patients, 26 responded clinically and radiographically within four weeks of initiation of therapy. Four of nine patients who underwent biopsy responded to treatment. There was no difference in these response rates (68% versus 44%, p = 0.24). The median survival of the empirically treated responders, from first diagnosis of AIDS to last follow-up, was 422 days. Among the 30 responders, five patients discontinued therapy and four of them had relapses. No relapses occurred in the 25 patients who continued full-dose therapy indefinitely (p = 0.0004). Sixteen of 30 patients (53%) receiving continuous therapy developed toxicity, which required a change in medication. There was no difference in the survival of patients who continued to receive sulfadiazine and pyrimethamine compared with those in whom clindamycin was substituted for sulfadiazine (median, 311 days versus 422 days, p = 0.25). CONCLUSION: A policy of empiric treatment of suspected Toxoplasma encephalitis is satisfactory, and patients who respond to such therapy and continue to take full therapeutic doses of anti-Toxoplasma drugs have relatively long survivals.
Two pairs of siblings with severe dystonia with marked diurnal fluctuation had both reduced CSF concentration of biopterin and marked symptomatic improvement of the dystonia in response to levodopa. Whether the reduced concentration of biopterin reflects focal abiotrophy of biopterin-containing neurons or deficiency of biopterin synthesis is uncertain. A fifth individual, who had a systemic deficiency of biopterin synthesis, shared the features of reduced biopterin in CSF, marked diurnal variation in the degree of dystonia, and clinical improvement in response to levodopa. Generalized dystonia with marked diurnal fluctuation was therefore shared by the four patients in whom biopterin deficiency was limited to the CNS and the patient with systemic deficiency of biopterin.
Six infants with cerebral infarcts were examined prospectively with real-time sonography to determine the sonographic characteristics of infarcts and their evolution. Patients' ages ranged from 1 day to 7 months, and serial sonographic and/or CT scans were obtained over a period of 2 weeks to 14 months in the survivors. Among our patients the most characteristic sonographic findings of infarction were absence of gyral definition, absence of vascular pulsations, altered parenchymal echogenicity, and territorial distribution. Mass effect, reflected in ventricular size and shift of midline structures, may also be seen and largely parallels the extent of the infarction. Evolution of infarcts was seen sonographically as gradual return of arterial pulsations and concurrent development of cystic spaces. Sonography was found to be a valuable tool in the diagnosis of infarction in infancy and in monitoring its evolution, although CT was necessary for adequate initial evaluation in older infants.
Cervical spine injuries pose devastating potential problems for surgeon and patient alike. This review will stress the early diagnosis of cervical spine injuries, with emphasis on early suspicion of injury. This review will focus on the radiology and types of lesions found with cervical spine injury.
A reversible affinity inhibitor of rat lens aldose reductase (RLAR), that can be transformed into an irreversible inhibitor by low doses of X-rays or by exposure to light, has been synthesized and characterized. The inhibitor consists of quercitrin, a reversible receptor binding moiety, that is connected through a hexanediamine spacer to an azido containing moiety which becomes chemically reactive when irradiated. This reagent, N-(2-nitro-4-azidophenyl)-hexamethylenediamine-N'-(3'-O-quercit rin), (NAP-HEX-Q), represents a new class of affinity agents which have potential applications as target-entrapped drugs. The KI's for quercitrin and NAP-HEX-Q, both non-competitive inhibitors, are 0.6 uM and 0.5 uM, respectively. Rates are calculated from the tangent of the angle of descent of the linear absorbance vs time plots, measured simply and rapidly with a protractor. Irreversible inhibition of RLAR by NAP-HEX-Q, as a function of the dose of irradiation with either X-rays or light, is consistent with apparent first order kinetics. NAP-HEX-Q is designed as a drug to prevent or reverse diabetic cataract formation by selective photoaffinity inhibition of RLAR with no significant effect on aldose reductase in other tissues. However, when not accessible to light, other potential target-entrapped drugs can be activated by low doses of X-rays at their targeted anatomic sites.
Two lysosomal storage diseases, cystinosis and Fabry disease, were diagnosed clinically in different members of a single sibship. The possibility that the affected sister and brother might have related disorders with disparate manifestations was pursued. The four principal family members were tested for heterozygote status with respect to serum and leukocyte alpha-galactosidase A activity, urinary trihexosylceramide excretion, and the capacity to engage in cystine counter-transport across leukocyte lysosome membranes. Results were consistent with classical autosomal recessive inheritance in the case of cystinosis and X-linked inheritance for Fabry disease, confirming that this family represents an example of two rare disorders occurring in the same sibship.
Terminal prepartum patterns from 31 patients were associated with 39% perinatal mortality rate and major degrees of perinatal asphyxia among survivors. Conditions most commonly associated with these patterns were intrauterine growth retardation, preeclampsia, and prolonged pregnancy. NST patterns in which there was absence of accelerations, absent or reduced variability, with or without variable or shallow late decelerations, portended very omnious outcomes when accompanied by absent fetal movements and/or oligohydramnios. Perinatal mortality was 39% under these circumstances. Immediate cesarean section is warranted when this situation is encountered.
Several studies have suggested that dietary fibers, especially water-soluble sources, are effective agents for lowering plasma cholesterol. This study was undertaken to determine the effect of various fibers on the composition of apoproteins in high density lipoproteins. Rats were fed experimental diets that contained either 20% wheat bran, oat bran or cellulose or 5% pectin or guar gum for 4 weeks. Final body weight was similar among groups. HDL cholesterol and total apoprotein concentrations were not significantly altered by diet. The percentage of apo A-I was significantly elevated and apo E and the apo C's were significantly lower in the guar gum group relative to the wheat bran group. Lecithin cholesterol acyl transferase activity and the C-II-to-C-III ratio were highest in the guar gum group. Differences in the absorption and subsequent metabolism of lipid could account for differences in HDL composition.
In the past, patients with injuries of the cervical spine and spinal cord have been diagnosed by means of myelography and polytomography. In an attempt to improve the radiographic evaluation of patients with cervical spinal cord injuries the authors performed computerized tomography (CT) scanning of the cervical spine following injection of metrizamide into the spinal subarachnoid space. In 23 patients with cervical spinal cord injuries, metrizamide myelography was performed via a C1-2 puncture. Myelography was used only for localization of the lesion and to determine the site of CT scanning. After myelography, CT scanning of the cervical spine in the transaxial plane was effective in determining the exact nature of compressive lesions and distinguishing the etiology among hematoma, disc, bone fragments, osteophytes, or ossification of the posterior longitudinal ligament. In several patients, metrizamide could be seen entering the spinal cord and was indicative of anatomical spinal cord disruption. In patients with fractures, CT scanning identified the site and nature of the injury without the need for turning the patient to the lateral position. In several patients with an apparently stable cervical spine, the CT scan showed apophyseal joint widening indicative of instability. The authors conclude that CT scanning of the cervical spine after the introduction of metrizamide into the subarachnoid space provides a definitive evaluation of the cervical spinal cord, the bone structures of the cervical spine, and their relationship to each other.
A prospective study of 460 midtrimester amniocenteses performed with ultrasonic guidance was made to determine the problems that occur during amniocentesis and the causes of dry or bloody taps. In 27 instances the needle was seen piercing the fetus. Thickening of the uterine wall, tenting of the membranes, and blocking of flow by the fetus were also observed. The dangers of advancing the needle blindly when no fluid is obtained at the predetermined depth is stressed. The use of active real-time ultrasonic guidance during amniocentesis is advocated.