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R L Rapport

Publications and source records attributed to R L Rapport.

At least 19 recordsLinked to original sources
PubMed1997

Dorsal approach to presacral biopsy: technical case report.

OBJECTIVE AND IMPORTANCE: Biopsy of the presacral space is often awkward, technically difficult, and unrewarding when the sacrum is intact and the procedure is performed either by open operation or with computed tomographic guidance through the abdomen or perineum. CLINICAL PRESENTATION: We describe a patient with metastatic adenocarcinoma who presented with leg pain and computed tomographic evidence of a high, small mass anterior to an intact sacrum. TECHNIQUE: By drilling a hole through the sacrum lateral to the canal and between the roots, a biopsy of such a mass may be performed easily, safely, and quickly. CONCLUSION: A dorsal approach to presacral biopsy may be easily performed with readily available technology.

Adenocarcinoma↗
PubMed1995

Distribution of unsaturated metabolites of valproate in human and rat brain--pharmacologic relevance?

The concentrations of valproate (VPA) and six of its pharmacologically active, unsaturated metabolites (E-delta 2-VPA, Z-delta 3-VPA, E-delta 3-VPA, E,E-delta 2,3'-VPA, delta 4-VPA, and E-delta 2,4-VPA) were measured in serum and cortical brain samples from 24 patients undergoing epilepsy surgery. Collectively, the six metabolites were present at concentrations < 13% of VPA brain concentrations. Because the six unsaturated metabolites were present at such low brain concentrations, we concluded that these metabolites probably did not contribute significantly to the anticonvulsant effect of VPA. Results from a parallel pharmacodynamic study in rats in which VPA was administered three times daily for 8 weeks supported this conclusion. Only three unsaturated metabolites (E-delta 2-VPA, delta 3-VPA, E,E-delta 2,3'-VPA) were detected in rat brain. No correlation was observed between the time course of anticonvulsant effect [as measured by the timed intravenous pentylenetetrazol (PTZ) test] and the time course of VPA or metabolite concentrations in rat brain. Despite the structural similarity of VPA and its metabolites, striking differences were observed in their serum protein binding and blood-brain distribution properties. In the human brain, VPA and delta 4-VPA exhibited brain-to-free serum concentration ratios that were less than unity. In contrast, compounds with the double bond at the 2- or 3-position had brain:free concentration ratios that were much higher than unity. The structure-distribution relationship observed with VPA and its unsaturated metabolites suggested that these branched-chain fatty acids differ in their asymmetric transport across the blood-brain barrier (BBB).

Adolescent↗
PubMed1992

Low and variable presence of valproic acid in human brain.

We studied the distribution of valproic acid (VPA) between brain (gray matter) and serum in 13 patients receiving chronic VPA therapy who underwent cortical resections for intractable seizures. Valproate concentration in cerebral cortex was remarkably low compared with either total or unbound valproate concentration in serum. The respective brain-to-serum partition ratios based on total and free drug in serum were 0.111 +/- 0.051 and 0.544 +/- 0.175. In comparison with other commonly used antiepileptic drugs, valproate has the distinction of exhibiting the lowest brain-to-blood partitioning. Moreover, the brain-to-serum concentration ratio varied over a four-fold range between patients. Some of this variability was related to variation in serum protein binding, as indicated by a modest correlation between the partition ratio and serum free fraction (r = +0.687). However, the brain-to-unbound concentration ratio still showed a three-fold variation. The variability in distribution of VPA between brain and blood is probably one of the underlying factors for the lack of a clearly definable therapeutic range of serum VPA concentration in epileptic patient populations.

Adolescent↗
PubMed1987

Keep singin' the Blues.

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Blue Cross Blue Shield Insurance Plans↗
PubMed1984

Cerebral organization of oral and signed language responses: case study evidence from amytal and cortical stimulation studies.

A normally hearing left-handed patient familiar with American Sign Language (ASL) was assessed under sodium amytal conditions and with left cortical stimulation in both oral speech and signed English. Lateralization was mixed but complementary in each language mode: the right hemisphere perfusion severely disrupted motoric aspects of both types of language expression, the left hemisphere perfusion specifically disrupted features of grammatical and semantic usage in each mode of expression. Both semantic and syntactic aspects of oral and signed responses were altered during left posterior temporal-parietal stimulation. Findings are discussed in terms of the neurological organization of ASL and linguistic organization in cases of early left hemisphere damage.

Adult↗
PubMed1983

Language function and dysfunction among Chinese- and English-speaking polyglots: cortical stimulation, Wada testing, and clinical studies.

Language functions in a group of Chinese- and English-speaking polyglots living in a multiracial society have been investigated by several methods: the effects of cortical stimulation on object-naming and reading tasks in patients who required awake craniotomy, lateralization of cerebral dominance for speech by the Wada Test, and the pattern of language loss and recovery following stroke. The data indicate that these polyglots were all left hemisphere dominant for the languages tested: no consistent evidence for increased participation by the right hemisphere for language functions was found. The cortical stimulation experiments provided data most compatible with the "differential localization" model of cerebral localization in bilingualism. The variable which most influenced performance in all of these investigations was which language was used primarily for speaking as well as reading and writing at the time of the study.

Adult↗
PubMed1981

Na+ + K+-ATPase in serially excised segments of epileptic monkey cortex.

The membrane-bound enzyme Na+ + K+-ATPase was measured in serially excised specimens of cerebral cortex in epileptic and control monkeys. Experimental chronic epileptic cortex showed significantly lower values than controls, as is seen in some other models and human epilepsy, but is different from the increased enzyme values in cobalt and freezing lesion epilepsy.

Aluminum Hydroxide↗
PubMed1981

Anterior encephalocele.

Eighteen cases of anterior encephalocele treated at the University of Malaya Hospital between 1970 and 1980 are discussed, and the literature concerning this defect is reviewed. A detailed analysis of the microscopic abnormalities present in the surgical specimens is included, along with the relevant radiographic and demographic data. Anterior encephalocele is more common in Southeast Asia than elsewhere. The possible ethnographic and geographic implications are presented, as well as a discussion of the relevant embryology, in attempting to define possible etiologies for this malformation. The author's surgical approach to the repair of this defect and reasons for preferring a transcranial, intradural approach are described. Potential complications are enumerated.

Adult↗
PubMed1979

Single-dose pharmacokinetics and anticonvulsant efficacy of primidone in mice.

The pharmacokinetics and efficacy of the anticonvulsant primidone (PRM) and its active metabolites, phenobarbital (PB) and phenylethylmalonamide (PEMA), were studied after single-dose administration in mice. The half-life of PB is twice that of PRM and PEMA. The plasma/brain ratios provide evidence of poor penetration of PRM into brain. The results support our findings of negligible or absent PRM concentrations in the brains of patients on primidone therapy who were undergoing surgery for intractable epilepsy. The anticonvulsant properties of PRM, PB, and PEMA against maximal electroshock in mice were also studied with the use of the metabolic inhibitor SKF 525A. The half-life, potency, peak anticonvulsant effect, and effective dose curves of these compounds indicate that the anticonvulsant effect of short-term oral PRM administration in mice is from derived PB.

Animals↗
PubMed1977

Phenytoin-related cerebellar degeneration without seizures.

Cerebellar changes have been reported in relationship to epilepsy alone as well as to phenytoin therapy for the control of seizures. The cliniconeuropathological correlation between these changes and epilepsy or the anticonvulsant is usually complicated by the presence of both variables. Experimental evidence suggests that phenytoin alone may be sufficient to cause cerebellar changes following intoxication. We report a case of cerebellar degeneration in a patient treated with isoniazid and prophylactically treated wtih phenytoin who never had a seizure.

Cerebellum↗