Biomedical subjects
Publications and source records attributed to R A Baker.
The Gouda stereotactic frame has been redesigned for use with computed tomography. The patient is attached to the frame, is scanned, and is moved to the operating room for stereotactic biopsy. The Gouda frame permits accurate biopsy of otherwise inaccessible tumors of the brain.
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We studied two cases of ataxic Creutzfeldt-Jakob disease. EEG, CT, evoked responses, and CSF were normal in one purely ataxic patient. Diagnosis was established by cerebellar biopsy. Autopsy demonstrated devastating spongiform changes in the cerebellum, basal ganglia, and thalamus with rare focal changes in cerebral cortex. In the second patient, late generalized changes developed with dementia. Diagnostic studies included abnormal visual evoked responses, CSF with abnormal oligoclonal bands and IgG, and subacute spongiform encephalopathy in frontal lobe biopsy. Early diagnosis is best established by biopsy of brain areas most likely to be involved on the basis of clinical neurologic findings.
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The Gouda stereotactic frame has been modified to interface with the GE 8800 scanner. The patient, attached to the frame, is scanned and then moved to the operating room for a stereotactic biopsy. This is a safe, accurate method of obtaining biopsy specimens of otherwise inaccessible tumors of the brain.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Strongyloidiasis and aseptic meningitis occurred in a renal transplant recipient who was receiving immunosuppressive drugs. Cure followed therapy with antibiotic administration for 3 days combined with oral thiabendazole, suggesting parasitic infection as the most likely cause of meningitis. Awareness of this disease and need for prompt institution of therapy is stressed. Prophylactic administration of thiabendazole is probably preventive.
The action spectrum and quantum efficiency (phi H+) for proton ejection from Halobacterium halobium have been determined under conditions chosen to minimize light-triggered proton influx which is usually observed in intact cells. The action spectrum for the carotenoid-containing strain, R1, shows that light energy absorbed by the carotenoids does not contribute to the proton ejection. After correction for shielding by the carotenoids and other cell pigments, the action spectrum closely follows the absorption spectrum of bacteriorhosopsin. Values determined for phi H+ in H. halobium cells and cell envelopes range from 0.4 to 0.7. These values are significantly higher than the currently accepted value for the quantum efficiency for the photoreaction cycle of bacteriorhodopsin in isolated purple membrane, suggesting that at least in intact cells and envelopes more than one proton is pumped during the bacteriorhodopsin photocycle. A new nondestructive assay for bacteriorhopopsin in intact cells and envelopes which also contain other pigments was used in this work.
Epidurography with metrizamide was performed on 9 Rhesus monkeys; physiologic saline was substituted for metrizamide in 3 control monkeys. Metrizamide successfully outlined the epidural space without causing any adverse clinical effects or direct tissue injury.
A Morse coronary manifold was modified for cerebral angiography. The modified unit permits easier identification of foreign particles which could form emboli. It also expedites the procedure by simplifying continuous irrigation and facilitating reloading of the injector.
The clinical findings in a group of 32 rheumatoid patients with symptomatic myelopathy are described. The myelopathy appeared in late middle age after many years of rheumatoid disease (average duration, 18 years). The most common radiological abnormality was anterior subluxation of C1. Other patterns occurred in about half the cases. The most common neurological findings were those of a mild to moderate spastic paraplegia, often with atrophy of muscles of the hands and sensory changes in the hands. Symptoms originating above the foramen magnum (nystagmus, diplopia, slurred speech) appeared to have a vascular cause and were sometimes associated with upward as well as posterior movement of the odontoid process. Root pain into the arms was not present, and its absence helped to distinguish these disorders from cervical spondylosis. Root pain into the territory of the C2 root was common. Medical or conservative therapy was not effective, and the preferred approach was use of a halo traction device followed by posterior fusion, with or without laminectomy. Pathologically, in 2 autopsy cases, the maximal change had occurred in the central gray matter and adjacent posterior and lateral columns. We postulate that direct pressure caused intermittent compression and narrowing of distal transverse branches of the anterior spinal artery.
The accuracy of CT scan diagnosis can best be studied by comparing the postmortem scan to the corresponding pathologic specimen. To be valid, this comparison must be made in a precise manner: the CT image plane and the pathologic slice plane must correspond anatomically and must be juxtaposed in a specific point-to-point manner. A new method is described which correlates postmortem CT scans and postmortem pathologic specimens. Also considered are the utility and the limitations of matching CT absorption values to homogeneous pathologic lesions such as neoplasms, infarcts, hemorrhage and edema.
Metrizamide, a non-ionic water-soluble contrast agent, was injected into the epidural spaces of 6 dogs to see if the posterior border of the L7-S1 interspace could be outlined. Between two and six Metrizamide epidurograms were obtained on each dog. The L7-S1 interspaces were usually well outlined. No complications were experienced by the dogs. The dogs were sacrificed at intervals between 3 days and 42 days following their last epidurogram in order to examine the epidural tissues for inflammatory changes. No histologic differences were observed between the control and experimental dogs.
Metrizamide ventriculography was used in 24 patients with suspected lesions in and near the third ventricle. The diagnoses were aqueduct stenosis (6), upper brain stem expansions (5), third ventricular tumors (6), craniopharyngiomas (2), subarachnoid cyst (1) and normal (1). Computed tomography was used as the guide to predict the likely causes of obstruction and to determine if ventricular shunting was appropriate before or after ventriculography. Several cases required pneumoencephalography in combination with ventriculography in order to determine whether an upper brain stem lesion was intrinsic or extrinsic.
Twenty pediatric and 180 adult patients underwent myelography using metrizamide (Amipaque). All patients were examined and interviewed before and after the studies. New or exacerbated symptoms attributed to metrizamide myelography were graded according to severity. After the procedure, 51 of 200 patients were unchanged from baseline. Headache was the most common complaint, with an overall incidence of 62%. Nausea and/or vomiting occurred in 38%. Back or leg pain, neck stiffness, temperature elevation, and a variety of less common manifestations were also observed. The incidence of sequelae was higher than in comparable Scandinavian studies with this contrast medium.