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Biomedical subjects

D Caplan

Publications and source records attributed to D Caplan.

At least 37 records · Page 2Linked to original sources
PubMed1995

Issues arising in contemporary studies of disorders of syntactic processing in sentence comprehension in agrammatic patients.

This paper reviews recent studies of sentence comprehension in agrammatic patients. The conclusion is reached that more detailed study of individual patients is necessary to support hypotheses that have been presented concerning the deficit in these patients and that the rationale for studying comprehension in this group of patients is not well developed. A set of suggested criteria is presented for patient analysis in this field.

Aphasia↗
PubMed1995

Analysis of lesions by MRI in stroke patients with acoustic-phonetic processing deficits.

We tested 10 aphasic stroke patients for the ability to discriminate and identify English phonemes. All patients underwent MRI and had their scans analyzed morphometrically. Patients with impairments in acoustic-phonetic processing tended to have lesions involving the left posterior supramarginal gyrus and the bordering parietal operculum, an observation further supported by regression and correlation analyses. These results are interpreted as evidence that the region including the left posterior supramarginal gyrus and parietal operculum plays a significant role in acoustic-phonetic processing.

Adult↗
PubMed1995

Lexical factors in the word-superiority effect.

In the Reicher-Wheeler paradigm, fluent readers can identify letters better when they appear in a word than when they appear in either a pronounceable pseudoword (a lexicality effect) or a single letter (a word-letter effect). It was predicted that if both of these effects involve a lexical factor, then adult acquired dyslexic subjects whose deficit prevents access to visual word form should show disruptions of the normal effects on the Reicher-Wheeler task. The results were that dyslexic subjects as well as matched control subjects showed a lexicality effect; however, while the control subjects showed a normal word-letter effect, the dyslexic subjects showed a reverse letter-superiority effect. Both effects, however, showed a systematic variation: As performance on lexical decision improved, the subjects' performance on words in the Reicher-Wheeler task was better than that for all the other conditions. These subject correlations were replicated by using data from a second lexical decision experiment, which utilized the same words and pseudowords that were used in the Reicher-Wheeler task. In addition, an item analysis showed that the words that the subjects had discriminated correctly in lexical decision showed a significant advantage over those that they had not, as well as an improvement relative to the other conditions. These results suggest that there is a lexical factor underlying the lexicality and word-letter effects, and it is proposed that the abnormal letter-superiority effect can be accounted for as the manifestation of other competing factors.

Adult↗
PubMed1994

Sentence comprehension in patients with Alzheimer's disease.

Twenty-three early-stage dementia of the Alzheimer type (DAT) patients and twenty-three control subjects were tested on a sentence-picture matching test containing nine different sentence types representing different levels of syntactic complexity. Subjects chose between drawings depicting a target sentence and a syntactic foil. Results indicated that DAT patients differed from control subjects on four of the nine sentence types. Performance of the patients was not poorer for sentences that were syntactically more complex, but was poorer for sentences that had two propositions as compared to one. Results are discussed in terms of a post-interpretative processing impairment in sentence comprehension in DAT.

Aged↗
PubMed1994

Selective acoustic phonetic impairment and lexical access in an aphasic patient.

The relationship between acoustic-phonetic disturbances and lexical access was explored in an aphasic patient. M.L. had a restricted disturbance of phonemic discrimination that affected the discrimination of voicing contrasts in nonword stimuli. Despite this impairment, her discrimination of voicing contrasts in words and her comprehension of auditorily presented words containing voiced segments was excellent. Performance on lexical decision was impaired: M.L.'s rejection of nonwords was poor and her reaction times and error rates for word stimuli showed a trend toward being influenced by the lexical status (word or nonword) of the item that would be formed by a change in voicing. The results are consistent with a role for a phonemic code in auditory word recognition, coupled with lexical-to-acoustic/phonetic feedback, but are also compatible with the view that other access codes for the Phonological Input Lexicon are also available.

Aged↗
PubMed1992

Articulatory and phonological determinants of word length effects in span tasks.

Several previous studies have shown that memory span is greater for short words than for long words. This effect is claimed to occur even when the short and long words are matched for the number of syllables and phonemes and so to provide evidence for subvocal articulation as being one mechanism that underlies memory span (Baddeley, Thomson, & Buchanan, 1975). The three experiments reported in this paper further investigate the articulatory determinants of word length effects on span tasks. Experiment 1 replicated Baddeley et al.'s finding of an effect of word length on auditory and visual span when the stimuli consist of words that differ in terms of the number of syllables. Experiments 2 and 3 showed that the effects of word length are eliminated when the words in the span task are matched for the number of syllables and phonemes but differ with respect to the duration and/or complexity of their articulatory gestures. These results indicate that it is the phonological structure of a word and not features of its actual articulation that determines the magnitude of the word length effect in span tasks.

Aged↗
PubMed1992

Postparathyroidectomy transient thyrotoxicosis.

Three patients are described who had spontaneously resolving transient thyrotoxicosis after resection of a parathyroid adenoma without thyroidectomy or an apparent thyroid abnormality before or during surgery. All had documented thyrotoxicosis that developed within 2 weeks after surgery, which was clinically symptomatic in two of three patients. The thyrotoxicosis was associated with subnormal radioactive iodine thyroid uptake when performed in the two symptomatic patients and was consistent with a postsurgical inflammatory etiology secondary to thyroid gland trauma during parathyroidectomy. In all patients, the clinical and biochemical evidence of thyrotoxicosis resolved within 2 months. Antithyroglobulin and antimicrosomal antibodies were not detected in the two patients who had a complete recovery 3 months after surgery. However, in the patient who had autoimmune thyroiditis, hyperthyroidism due to Graves' disease subsequently developed 19 months after parathyroidectomy and was associated with increasing titers of antithyroglobulin and antimicrosomal thyroidal autoantibodies. From these observations, we conclude that 1) spontaneously resolving transient thyrotoxicosis of varying severity may occur in some patients after parathyroidectomy, which could be secondary to intraoperative thyroid gland manipulation, and 2) while the occurrence of subsequent Graves' hyperthyroidism in a patient with underlying autoimmune thyroiditis may have been a coincidence, this observation also raises the possibility that thyroidal autoantigen released during parathyroidectomy may trigger the reactivation of autoimmune thyroid disease in a predisposed subject.

Adolescent↗
PubMed1991

The relationship of depression to symptomatology and lesion site in aphasic patients.

The prevalence of depression was examined in 54 patients recruited by speech pathologists and separated into four groups according to aphasia type (Broca's vs Wernicke's) and the duration of illness (less than six months vs more than six months). Evaluation of depression was made through questionnaires, completed by the spouse or speech pathologist, and patient interviews. The four groups were similar in demographical variables, in severity of aphasia and in lesion size (from CAT scan analyses). The prevalence of depression for the total sample was low (15%). Univariate analyses (ANOVA) did not show significant differences between the groups on the depression scales. The severity of depression was not correlated with lesion size or location. It was concluded that Wernicke's aphasics do not experience depression less often nor less severely than Broca's aphasics and that the incidence of depression in aphasia is not high. These results are in contrast with those obtained in earlier studies. Reasons for the discrepancies between this and other studies are discussed.

Aged↗
PubMed1991

Nutritional issues in pediatric inflammatory bowel disease.

Malnutrition, characterized by weight loss, growth failure and micronutrient depletion, are prominent features of inflammatory bowel disease (IBD) in the pediatric age group. Accurate evaluation of the patient's nutritional status and appropriate nutritional support, whether enteral or parenteral, constitute integral parts of the management of the growing child with IBD. Over the past two decades, a number of studies have supported the potential use of nutritional therapy to induce remission and to control disease activity in symptomatic Crohn's disease. More recently, preliminary studies on the use of dietary supplements of marine-oil-derived omega-3 fatty acids have also indicated a beneficial effect in IBD patients. In parallel with these clinical trials, scientific research has recently focused on the concept that specific dietary alterations can modulate the immune response. Components of the diet that may have particular relevance to mucosal immunity and the pathogenesis of IBD include polyunsaturated fatty acids, nucleotides, and amino acids such as glutamine and arginine. Future research in the interactions between specific nutrients and the immune system will likely increase our understanding of the causes of IBD, as well as enhance the development of novel nutritional therapies for IBD patients.

Child↗
PubMed1990

Campylobacter gastritis simulating Menetrier's disease by upper gastrointestinal radiography.

Within this decade it has been determined that primary gastritis in both children and adults is frequently associated with infection of the gastric mucosa with Campylobacter pylori. It is characterized by a chronic inflammatory process in which the mucosa of the gastric antrum is typically most severely involved. Other regions of the stomach may be involved and associated peptic ulcers of the stomach and duodenal bulb are frequent. A case of C. pylori gastritis is reported in which involvement of the gastric fundus and body produced severe rugal hypertrophy that resembled Menetrier's disease.

Campylobacter Infections↗
PubMed1990

The effects of syntactic structure on discourse comprehension in patients with parsing impairments.

Syntactic complexity was systematically manipulated in sentence and discourse comprehension tasks. Aphasic patients, but not normal controls, showed effects of syntactic structure in the sentence comprehension task. Neither aphasic nor control subjects showed significant differences between the comprehension of syntactically simple and complex stories. This pattern confirms the clinical impression that some discourses can be understood by patients who cannot utilize syntactically based sentence comprehension mechanisms.

Adult↗
PubMed1990

Syntactic comprehension in Japanese aphasics: effects of category and thematic role order.

Syntactic comprehension disturbances in Japanese aphasics were investigated focusing on the role of category order and thematic role order. The data from Japanese aphasics show that the canonicity of thematic role order determines the ease of interpretation of different sentence types. This finding implies that language-specific factors, rather than language-universal factors, influence the sentence comprehension mechanisms that are retained by aphasic patients.

Aphasia↗
PubMed1990

Characteristics of syntactic comprehension deficits following closed head injury versus left cerebrovascular accident.

Two studies examined the ability to assign thematic roles and to coindex referentially dependent noun phrases in closed head injured adults, adult stroke patients, and normal adults. The subjects' task was to enact target sentences by manipulating toy animals. Closed head injured and stroke patients demonstrated a significant effect of syntactic structure on sentence comprehension, and the patterns of breakdown in the ability to assign thematic roles and coindex referentially dependent noun phrases were strikingly similar in the two groups. These findings suggest that syntactic comprehension disturbances are similar following left cerebral hemisphere infarction and closed head injury.

Adolescent↗