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Biomedical subjects

R C Martin

Publications and source records attributed to R C Martin.

At least 91 records · Page 5Linked to original sources
PubMed1987

Specific auditory perceptual dysfunction in a learning disabled child.

An 11 1/2 year old child with learning disability was evaluated with a battery of auditory and linguistic test procedures: electrophysiologic (auditory brain stem, middle latency response, and late potentials), electroacoustic (stapedial reflexes), and behavioral (measures of phonetic-phonologic, syntactic, and semantic processing). The overall pattern of results suggested the presence of an isolated auditory-phonologic processing disorder. Results supported an auditory-perceptual, as opposed to a linguistic-cognitive, model of learning disability.

Aptitude↗
PubMed1986

Evidence of syntactic deficits in a fluent aphasic.

The syntactic abilities of a mild Wernicke's aphasic were examined in production and comprehension tasks. The patient made few errors involving the omission or substitution of substantives or grammatical markers, especially after the first few weeks of testing. Despite his good ability to produce sentences with acceptable surface form, he continued to make role reversal errors and to produce a restricted range of syntactic forms. In comprehension, he also demonstrated an impairment in his ability to use the syntactic information in a sentence to assign role relations. These syntactic impairments could not be attributed to a short-term memory deficit as the patient showed only a slightly reduced short-term memory span, and showed evidence of having a normal phonological store. Implications for theories of aphasic deficits as well as for theories of normal language processing are discussed.

Aphasia↗
PubMed1982

Short-term memory performance in the absence of phonological coding.

These experiments examined the short-term memory performance of an aphasic patient with posterior damage who shows a selective deficit in phonological coding. In recognition memory tests, the patient relied on both visual and semantic coding, and often showed an essentially normal level of accuracy. However, for memory sets consisting of four function words, his performance was quite impaired. Also, his retention of order information was far below that of normal controls. The implications of these deficits in short-term memory for language comprehension and production are discussed.

Aphasia↗
PubMed1980

Classification in well-defined and ill-defined categories: evidence for common processing strategies.

Early work in perceptual and conceptual categorization assumed that categories had criterial features and that category membership could be determined by logical rules for the combination of features. More recent theories have assumed that categories have an ill-defined structure and have prosposed probabilistic or global similarity models for the verification of category membership. In the experiments reported here, several models of categorization were compared, using one set of categories having criterial features and another set having an ill-defined structure. Schematic faces were used as exemplars in both cases. Because many models depend on distance in a multidimensional space for their predictions, in Experiment 1 a multidimensional scaling study was performed using the faces of both sets as stimuli, In Experiment 2, subjects learned the category membership of faces for the categories having criterial features. After learning, reaction times for category verification and typicality judgments were obtained. Subjects also judged the similarity of pairs of faces. Since these categories had characteristic as well as defining features, it was possible to test the predictions of the feature comparison model (Smith et al.), which asserts that reaction times and typicalities are affected by characteristic features. Only weak support for this model was obtained. Instead, it appeared that subjects developed logical rules for the classification of faces. A characteristic feature affected reaction times only when it was part of the rule system devised by the subject. The procedure for Experiment 3 was like that for Experiment 2, but with ill-defined rather than well-defined categories. The obtained reaction times had high correlations with some of the models for ill-defined categories. However, subjects' performance could best be described as one of feature testing based on a logical rule system for classification. These experiments indicate that whether or not categories have criterial features, subjects attempt to develop a set of feature tests that allow for exemplar classification. Previous evidence supporting probabilistic or similarity models may be interpreted as resulting from subjects' use of the most efficient rules for classification and the averaging of responses for subjects using different sets of rules.

Concept Formation↗
PubMed1979

South American blastomycosis of epididymis.

Reported herein is the first Brazilian case of epididymal involvement by South American blastomycosis, and apparently the second case to be reported in the world literature.

Amphotericin B↗
PubMed1976

Prolongation of postoperative disease-free interval and survival in human colorectal cancer by B.C.G. or B.C.G. plus 5-fluorouracil.

83 patients with colorectal carcinoma of the Dukes' C class were randomised to receive postoperative adjuvant therapy with B.C.G. alone or in combination with oral doses of 5-fluorouracil (5-F.U.), and have been followed for up to thirty months. Results were compared with carefully selected historical controls who were treated by surgery alone. A statistically significant prolongation of both disease-free interval and overall survival was observed in 50 patients receiving the combination of B.C.G. and 5-F.U. (P=0.03, P=0.01 respectively) as well as in 33 patients receiving B.C.G. alone (P=0.03, P=0.05 respectively). The efficacy of B.C.G.+5-F.U. was independent of the number of tumour-involved lymph-nodes in the surgical specimen. In contrast, B.C.G. given alone appears to be highly effective among 10 patients with 6 or more positive lymph-nodes (P less than 0.04) and ineffective (as yet) among 23 patients with 5 or less positive lymph-nodes. These results suggest that adjuvant immunotherapy, with or without chemotherapy, can improve the prognosis of surgically treated patients with colorectal carcinoma of the Dukes' C class.

Administration, Oral↗
PubMed1975

Adjuvant immunotherapy and chemoimmunotherapy in colorectal cancer of the Dukes' C classification. Preliminary clinical results.

Fifty-eight patients with Dukes' C classification of carcinoma of the large bowel were placed on adjuvant immuno- or chemoimmunotherapy with Bacillus calmette guerin (BCG) or combination of 5-fluorouracil (5-FU) plus BCG following primary and definitive surgery, and were followed for up to 21 months. Of twenty-six patients receiving BCG alone by scarification, five have relapsed with 75% of freedom from disease estimated at 15.1 months compared with 10.1 months in a group of carefully selected historical controls who had surgery alone (p = 0.12). The survival of all patients receiving BCG alone has not reached the 75 percentile yet, and the difference from controls is currently estimated at the 18% level. The combination of 5-FU plus BCG (studied in 32 patients) may be superior to BCG alone at this time, in that it appears to more effectively protect against tumor recurrence (75 percentile not yet reached compared to control, (p = 0.08). The survival of patients on 5-FU plus BCG also appears to be improved (p = 0.09). No patients have expired compared to a 75 percentile survival of 16.6 months in the control. Serial determination of plasma CEA was crucial in the clinical follow-up of these patients. Frequent CEA detetminations have led to early detection of clinical relapse. In the elevation of CEA suggests tumor recurrence with a high degree of probability in patients with past history of cancer of the large bowel.

BCG Vaccine↗
PubMedDate not supplied

Production, distribution and applications of californium-252 neutron sources.

The radioisotope 252Cf is routinely encapsulated into compact, portable, intense neutron sources with a 2.6-yr half-life. A source the size of a person's little finger can emit up to 10(11) neutrons s(-1). Californium-252 is used commercially as a reliable, cost-effective neutron source for prompt gamma neutron activation analysis (PGNAA) of coal, cement and minerals, as well as for detection and identification of explosives, land mines and unexploded military ordinance. Other uses are neutron radiography, nuclear waste assays, reactor start-up sources, calibration standards and cancer therapy. The inherent safety of source encapsulations is demonstrated by 30 yr of experience and by US Bureau of Mines tests of source survivability during explosions. The production and distribution center for the US Department of Energy (DOE) Californium Program is the Radiochemical Engineering Development Center (REDC) at Oak Ridge National Laboratory (ORNL). DOE sells 252Cf to commercial reencapsulators domestically and internationally. Sealed 252Cf sources are also available for loan to agencies and subcontractors of the US government and to universities for educational, research and medical applications. The REDC has established the Californium User Facility (CUF) for Neutron Science to make its large inventory of 252Cf sources available to researchers for irradiations inside uncontaminated hot cells. Experiments at the CUF include a land mine detection system, neutron damage testing of solid-state detectors, irradiation of human cancer cells for boron neutron capture therapy experiments and irradiation of rice to induce genetic mutations.

Boron Neutron Capture Therapy↗
PubMedDate not supplied

Development of high-activity 252Cf sources for neutron brachytherapy.

The Gershenson Radiation Oncology Center of Wayne State University (WSU), Detroit, Michigan, is using 252Cf medical sources for neutron brachytherapy. These sources are based on a 20-year-old design containing < or = 30 micrograms 252Cf in the form of a cermet wire of Cf2O3 in a palladium matrix. The Radiochemical Engineering Development Center (REDC) of Oak Ridge National Laboratory has been asked to develop very compact, high-activity 252Cf neutron sources for use with remote afterloading equipment in order to reduce treatment times and dose to clinical personnel and to expedite treatment of brain and other tumors. To date, the REDC has demonstrated that 252Cf loadings can be greatly increased in cermet wires and with much smaller diameters. Equipment designed for hot cell fabrication of these wires is being tested. A parallel program is under way to relicense the existing source design for fabrication at the REDC.

Brachytherapy↗
PubMedDate not supplied

Effects of unilateral vascular lesions and gender on visual spatial and auditory verbal attention span.

Unilateral cerebral vascular accidents (CVA) produce dominant hemisphere deficits in language and verbal memory, while nondominant hemisphere lesions often impair visual spatial analysis and visual memory. However, effects of unilateral lesions are less specified for visual spatial and auditory verbal attention span. The present study investigated whether tasks of attention span were sensitive to the effects of unilateral strokes. Left CVA females and males were compared to right CVA females and males on these measures. Age and education were not significantly related to performance Significant gender by stroke laterality interactions were found for the visual spatial attention span tasks. Left CVA females performed significantly worse than the other CVA groups on the visual spatial measures. These results suggest that there may be gender related differences in the effects of unilateral CVA on tasks of attention span.

Journal Article↗