PubMed Health⌕ Search

Biomedical subjects

K Patterson

Publications and source records attributed to K Patterson.

At least 91 records · Page 5Linked to original sources
PubMed1996

Naming and knowing in dementia of Alzheimer's type.

We studied the relationship between naming and the integrity of physical and associative knowledge in a group of patients with dementia of the Alzheimer type (DAT) and matched normal controls. All subjects named 48 line drawings and later generated verbal definitions in response to the names of a subset of the 48 items, which included a minimum of six definitions for correctly named objects and six definitions for items that the subject failed to name. A comprehensive scoring system was designed for the definitions, including physical and associative features of a general and a specific type, a superordinate label, the core concept, and various categories of errors. The definitions generated by the DAT patients, even those in the minimal group, contained significantly less correct information than those of normal subjects, and definitions corresponding to unnamed items were more impoverished than those for named items. Particularly striking was the loss of core concept for unnamed items. There was also a disproportionate reduction in physical information on unnamed compared to named items. We conclude that quantitative assessment of verbal definitions is a sensitive index of semantic memory breakdown. Our findings offer some support for the hypothesis that successful naming depends upon integrity of the subset of semantic knowledge comprising physical features.

Aged↗
PubMed1996

Nonfluent progressive aphasia and semantic dementia: a comparative neuropsychological study.

Two patients with nonfluent progressive aphasia, who have been studied longitudinally, are contrasted with a group of 5 patients with fluent progressive aphasia or semantic dementia. The most prominent feature of the nonfluent syndrome is the severe distortion of speech output with phonological errors and agrammatic sentence structure. This contrasts with the fluent, well articulated and syntactically correct, but empty, anomic speech found in semantic dementia. Performance on tests of comprehension separates the patient groups: The nonfluent patients show normal single-word comprehension, but marked impairment on tests of syntactic comprehension, while those with semantic dementia demonstrate the opposite pattern. Category fluency is severely defective in semantic dementia, but initial letter-based fluency is more impaired in the nonfluent syndrome. Performance on nonverbally mediated tests of semantic knowledge is impaired in semantic dementia only. The 2 forms of progressive aphasia have in common the sparing of perceptual and visuospatial skills, nonverbal problem solving abilities, and day-to-day (episodic) memory. Neuroradiological investigations have shown marked selective and striking inferolateral left temporal lobe atrophy in all 5 patients with semantic dementia. The changes in nonfluent progressive aphasia appear to be less focal and involve left perisylvian structures more diffusely. These 2 forms of progressive aphasia are, we argue, distinct in their manifestations.

Aged↗
PubMed1996

Understanding normal and impaired word reading: computational principles in quasi-regular domains.

A connectionist approach to processing in quasi-regular domains, as exemplified by English word reading, is developed. Networks using appropriately structured orthographic and phonological representations were trained to read both regular and exception words, and yet were also able to read pronounceable nonwords as well as skilled readers. A mathematical analysis of a simplified system clarifies the close relationship of word frequency and spelling-sound consistency in influencing naming latencies. These insights were verified in subsequent simulations, including an attractor network that accounted for latency data directly in its time to settle on a response. Further analyses of the ability of networks to reproduce data on acquired surface dyslexia support a view of the reading system that incorporates a graded division of labor between semantic and phonological processes, and contrasts in important ways with the standard dual-route account.

Dyslexia↗
PubMed1996

Hearing and saying. The functional neuro-anatomy of auditory word processing.

The neural systems involved in hearing and repeating single words were investigated in a series of experiments using PET. Neuropsychological and psycholinguistic studies implicate the involvement of posterior and anterior left perisylvian regions (Wernicke's and Broca's areas). Although previous functional neuroimaging studies have consistently shown activation of Wernicke's area, there has been only variable implication of Broca's area. This study demonstrates that Broca's area is involved in both auditory word perception and repetition but activation is dependent on task (greater during repetition than hearing) and stimulus presentation (greater when hearing words at a slow rate). The peak of frontal activation in response to hearing words is anterior to that associated with repeating words; the former is probably located in Brodmann's area 45, the latter in Brodmann's area 44 and the adjacent precentral sulcus. As Broca's area activation is more subtle and complex than that in Wernicke's area during these tasks, the likelihood of observing it is influenced by both the study design and the image analysis technique employed. As a secondary outcome from the study, the response of bilateral auditory association cortex to 'own voice' during repetition was shown to be the same as when listening to "other voice' from a prerecorded tape.

Auditory Perception↗
PubMed1996

Progressive biparietal atrophy: an atypical presentation of Alzheimer's disease.

OBJECTIVES: To define the clinical, neuropsychological, and radiological features of bilateral parietal lobe atrophy. METHODS: Four patients underwent a comprehensive longitudinal neuropsychological assessment, as well as MRI and HMPAO-SPECT. RESULTS: The consistent findings in the patients were early visuospatial problems, agraphia of a predominantly peripheral (or apraxic) type, and difficulty with bimanual tasks, all of which outweighted deficits in memory and language until later in the course of the illness. As the disease progressed, impairments in the phonological aspects of language and in auditory-verbal short term memory were often striking, perhaps reflecting spread from the parietal lobe to perisylvian language areas. Three patients went on to develop a global dementia and fulfilled the criteria for a clinical diagnosis of probable Alzheimer's disease; the fourth patient has only recently been identified. Neuroimaging disclosed bilateral parietal lobe atrophy (MRI) and hypoperfusion (SPECT), which was out of proportion to that seen elsewhere in the brain. One patient has died and had pathologically confirmed Alzheimer's disease with particular concentration in both superior parietal lobes. CONCLUSIONS: Bilateral biparietal atrophy is a recognisable clinical syndrome which can be the presenting feature of Alzheimer's disease. Although the label "posterior cortical atrophy" has been applied to such cases, review of the medical literature suggests that this broad rubric actually consists of two main clinical syndromes with features reflecting involvement of the occipitotemporal (ventral) and biparietal (dorsal) cortical areas respectively.

Aged↗
PubMed1996

Life domains and adaptive strategies of a group of low-income, well older adults.

Older adults are at increased risk for a variety of physical and functional limitations that threaten their ability to lead independent and fulfilling lives. Consequently, they stand to benefit from personalized strategies of adaptation that enable them to achieve successful outcomes in their daily activities and desired goals. In the current investigation, a qualitative descriptive methodology was used to document the perceived life domains of importance and associated strategies of adaptation of 29 residents of Angelus Plaza, a federally subsidized apartment complex in downtown Los Angeles for low-income, well older adults. On the basis of interview data, 10 life domains were identified, and within each domain, a typology of adaptive strategies was derived. The domains were activities of daily living (ADL), adaptation to a multicultural environment, free time usage, grave illness and death-spirituality, health maintenance, mobility maintenance, personal finances, personal safety, psychological well-being and happiness, and relationships with others. Although the typology should not be generalized to a geriatric population, therapists may wish to refer to it to gain a sense of the extent to which certain adaptive strategies may be applicable to the lives of particular older adults to whom they deliver services. The teaching of these adaptive strategies could then be incorporated into an individualized treatment plan. The typology also provides a broad picture of the kinds of adaptive strategies used by the older adults as a way of coping and adapting to their setting. Although some of the domains do not differ from those typically addressed in occupational therapy textbooks on geriatric care (e.g., ADL, health maintenance), others seem uniquely tailored to the specifics of the Angelus Plaza context (e.g., personal safety). Finally, certain domains emerged that may be highly relevant to older adults in most settings but are not typically the focus of occupational therapy programs (e.g., grave illness and death-spirituality, relationships with others). The emergence of these domains from our data suggests that therapists may wish to consider them more in treatment if they are convinced that they possess local relevance.

Activities of Daily Living↗
PubMed1996

Slow-flow phenomena in magnetic resonance imaging of the jugular bulb masquerading as skull base neoplasms.

Enhancement in the region of the jugular foramen on magnetic resonance imaging (MRI) is highly sensitive to the presence of a skull base neoplasm. Unfortunately, this imaging method lacks the specificity to be the sole criterion in the diagnosis of a lesion of the jugular foramen. Although well described in the radiological literature, the phenomenon of gadolinium enhancement of the relatively static blood in the jugular system continues to be erroneously diagnosed as glomus jugulare tumor. Instances of this phenomenon present in patients referred to our practice for surgical opinions before radiation therapy and/or definitive resection will be presented. The purpose of this communication is to bring this potential treatment pitfall to the attention of the neurotology community. Treatment planning for lesions of the lateral skull base cannot singularly be based on MRI findings but requires a healthy skepticism satisfied only by more complete evaluation.

Adult↗
PubMed1995

Is semantic memory consistently impaired early in the course of Alzheimer's disease? Neuroanatomical and diagnostic implications.

To establish whether semantic memory is consistently impaired in patients with very mild dementia of Alzheimer's type (DAT), we assessed episodic and semantic memory in 52 patients with DAT who were divided into three sub-groups according to dementia severity on the Mini-Mental State Examination (minimal > 23, mild 17-23 and moderate < 17) and 24 matched controls. The minimal group showed impairment on the following semantic memory measures: category fluency, naming of line drawings, naming to verbal description, answering semantic feature questions and a non-verbal picture-picture matching task (the Pyramids and Palm Trees Test). The mild and moderate groups showed additional deficits on picture sorting and word-picture matching tests. Within the minimal and mild groups there was, however, considerable heterogeneity. While some patients showed a consistent impairment across all of the semantic memory tests, others were impaired on only on a subset of these tests and a few even performed flawlessly. In contrast, all patients showed a profound deficit in episodic memory: delayed recall of new verbal and non-verbal material appears to be a particularly sensitive marker of early DAT. These data are in keeping with recent neuropathological studies demonstrating that the transentorhinal region is consistently involved at a very early stage. Lesions in this site cause a functional disconnection of the hippocampus, and hence a profound episodic memory disorder. The fact that many, but not all, patients with early disease also show impairment of semantic memory suggests that damage to the transentorhinal region is not sufficient to produce significant disruption of semantic memory. Such disruption reliably occurs, we hypothesize, only when the pathology extends to the temporal neocortex proper.

Aged↗
PubMed1995

Semantic effects in single-word naming.

Three experiments demonstrated that, for lower frequency words, reading aloud is affected not only by spelling-sound typicality but also by a semantic variable, imageability. Participants were slower and more error prone when naming exception words with abstract meanings (e.g., scarce) than when naming either abstract regular words (e.g., scribe) or imageable exception words (e.g., soot). It is proposed that semantic representations of words have the largest impact on translating orthography to phonology when this translation process is slow or noisy (i.e., for low-frequency exceptions) and that words with rich semantic representations (i.e., high-imageability words) are most likely to benefit from this interaction.

Adult↗
PubMed1995

MR imaging of bone marrow in children with osteosarcoma: effect of granulocyte colony-stimulating factor.

OBJECTIVE: Granulocyte colony-stimulating factor (GCSF) is used to stimulate myeloid cell production and function in children undergoing chemotherapy for osteosarcoma. We hypothesize that GCSF can cause reconversion of marrow from fatty to hematopoietic and that this change can be detected by MR imaging at sites away from the primary tumor. This benign effect of treatment should not be confused with tumor spread. MATERIALS AND METHODS: MR images of marrow of the affected and contralateral limbs were retrospectively reviewed for 16 patients with osteosarcoma of the femur or tibia; nine of these patients had received GCSF. A grade was assigned to marrow signal intensity at sites away from the tumor, and findings before and after treatment were compared. The validity of MR image interpretation was assessed by comparing the signal intensity of marrow with the histologic appearance of marrow at 19 resection margins. RESULTS: Changes consistent with reconversion were seen on MR images in seven of nine patients who had received GCSF in addition to chemotherapy and in none of seven patients who had received chemotherapy alone. The difference in proportions was statistically significant (p = .006; Fisher's exact test, two tailed). The histologic appearance of marrow at the resection margins agreed with the interpretation of the short-Tl inversion recovery sequence in all cases (100%). CONCLUSION: The findings suggest that GCSF causes changes in the MR imaging appearance of marrow. Histologic correlation supports the hypothesis that these changes are attributable to reconversion from fatty to hematopoietic marrow. Awareness of this finding is important to avoid false-positive diagnosis of marrow metastases.

Adolescent↗
PubMed1995

Evaluation of a semi-automated reticulocyte counting method using the Coulter STKS-2A blood cell counter.

Reticulocyte counting was assessed on the Coulter STKS-2A automated blood cell counter. Using a two step procedure, blood samples were first incubated with the supravital stain new methylene blue. An acidic reagent was then added to clear the haemoglobin and any stained RNA was preserved within the cell. The cells were then analysed by measurement of volume, conductivity and light scatter (VCS). The results of 123 samples analysed on the STKS-2A were compared with those from a Toa Sysmex R-1000 reticulocyte counter. One hundred and seven samples gave no review flags and reticulocyte counts ranging from 0.5% to 22.8%, resulting in a correlation coefficient of 0.93 for the methods. Between run imprecision studies gave CVs ranging from 5.3% for a reticulocyte count of 8.7% to a CV of 16.3% for a 0.34% count. Stability studies showed insignificant changes over 72 h storage. These findings confirm that VCS technology can be adapted to provide precise and accurate routine reticulocyte analysis.

Automation↗
PubMed1994

The relationship between comprehension and oral reading in progressive fluent aphasia.

The role played by comprehension in oral reading was investigated in three patients with progressive fluent aphasia. For patients J.L. and G.C., there was evidence of a deficit in semantic memory affecting both word production and comprehension. F.M., although equally anomic, had significantly better single-word comprehension than either J.L. or G.C. It was predicted that, for J.L. and G.C., success or failure in word comprehension should show item-specific correspondence with success or failure in reading exception words, but not regular words. This predicted pattern was obtained between word-picture matching tests and reading. For F.M., with only minimal comprehension impairment for the items used, a smaller trend in the same direction was observed. The results are discussed with respect to Patterson and Hodges' hypothesis (Neuropsychologia 30, 1025-1040, 1992) regarding the consequences of impaired semantic memory for the integrity of representations in the phonological output lexicon.

Aphasia↗
PubMed1994

Congenital tumors of the dorsum of the tongue.

Five children presented with masses on the dorsum of the tongue. Excisional biopsies were performed. Histologic examination showed the masses to be lipoblastomas, hamartomas and one heterotopic neuroglial tissue. A description of the clinical presentation and pathological nature of these lesions is presented.

Child↗
PubMed1994

Brain activity during reading. The effects of exposure duration and task.

Brain activity during reading tasks was investigated using PET. The aim was to account for differences in the results of two previous studies [those of Petersen et al. (Science 1990; 249: 1041-4) and Howard et al. (Brain 1992; 115: 1769-82)] by systematically varying the type of reading task and the exposure duration of the word stimuli. Both variables strongly influenced patterns of brain activity. There were three types of task: (i) reading aloud; (ii) reading silently; and (iii) lexical decision on visually presented words and pseudowords. Reading aloud and reading silently engaged the left middle and superior temporal regions, confirming the important role of these areas in visual word processing. The areas principally engaged during lexical decision were the left inferior and middle frontal cortices and the supplementary motor area; activity in these areas suggests that the subjects were using a phonological strategy to perform the task. There was also a significant effect of exposure duration, with activity being greater for short (150 ms) exposure durations than for long (1000 ms or 981 ms) exposure durations. We conclude that until we understand how subtle variations in experimental design influence brain activity during reading tasks, the association of specific processing functions with individual anatomical areas activated during reading is premature.

Adult↗
PubMed1994

Follicle-stimulating hormone (FSH) increases FSH receptor messenger ribonucleic acid while decreasing FSH binding in cultured porcine granulosa cells.

The goal of the present studies was to compare direct effects of porcine FSH (pFSH) on [125I]pFSH-binding sites with effects of pFSH on FSH receptor mRNA in cultured porcine granulosa cells. Cells from immature follicles were cultured on laminin-coated plates in serum-free medium for up to 6 days in the absence or presence of pFSH (1-100 ng/ml) or cholera toxin (0.04-400 ng/ml), which activates adenylyl cyclase independently of the FSH receptor. RRA indicated that [125I] pFSH binding to cells cultured without stimulator increased more than 10-fold with time in culture. Addition of pFSH to cultures resulted in a dose-dependent decrease in binding, assessed after removal of bound pFSH. Equilibrium saturation binding analysis indicated that pFSH (10 ng/ml) caused a 39% decrease in binding sites in cells cultured for 6 days. At the same time, pFSH increased progesterone production 9.5-fold. Cholera toxin (4 ng/ml) increased [125I]pFSH binding 110% and progesterone production 8.9-fold. Northern hybridization analysis of cultured granulosa cell mRNA using a porcine FSH receptor cDNA revealed three transcripts for the FSH receptor [2.2, 3.5, and 4.2 kilobases (kb)], with the major transcript being 4.2 kb in length. Addition of either pFSH (10 ng/ml) or cholera toxin (10 ng/ml) to cultures of granulosa cells increased the intensity of pFSH receptor transcripts compared with control values, with the 4.2-kb message remaining predominant. Hybridization with a porcine LH receptor cDNA revealed different transcripts (2.4, 4.0, 4.7, 7.0, and 11.0 kb), with the major transcript being 4.7 kb in length. Addition of either pFSH or cholera toxin to the cultures increased the intensity of all LH receptor transcripts; however, cholera toxin was more effective than pFSH. pFSH and cholera toxin increased the intensity of each species to different extents, although the 4.7-kb transcript remained predominant. These results indicate that exposure to FSH in culture results in down-regulation of the FSH receptor. Down-regulation is accompanied by increased FSH receptor mRNA levels, suggesting that FSH enhances FSH receptor synthesis.

Animals↗
PubMed1993

Expression of transforming growth factor-beta isoforms in small round cell tumors of childhood. An immunohistochemical study.

The transforming growth factor (TGF)-betas are a highly conserved group of potent multifunctional cell regulatory proteins with variable effects on cell growth and differentiation. Most of the small round cell group of childhood tumors are thought to arise from either primitive mesenchyme or neuroectoderm and show evidence of skeletal muscle or neural differentiation, and rarely both. To investigate the possibility that the TGF-betas have a role in the growth or differentiation of these neoplasms, we used antibodies specific for peptide sequences of the three known mammalian TGF-beta isoforms (TGF-betas 1, 2, and 3) to probe for TGF-beta protein expression in a total of 49 cases. TGF-beta 1 immunoreactivity was present in 16/17 (94%) of rhabdomyosarcomas, and the staining intensity was usually strong. TGF-beta 1 was also present in three of three ectomesenchymomas. In contrast, TGF-beta 1 was absent in all but one out of nine poorly differentiated neuroblastomas. Differentiating neuronal cells of ganglioneuroblastomas, however, were strongly positive for TGF-beta 1. Ewing's sarcomas and peripheral primitive neuroectodermal tumors had a less consistent, but usually positive, staining pattern. TGF-beta 3 staining patterns were very similar to those of TGF-beta 1. TGF-beta 2 immunoreactivity was only rarely detected in this group of tumors. The results suggest different roles for TGF-betas 1 and 3 in neuroblastoma and rhabdomyosarcoma. Expression of TGF-betas 1 and 3 is associated with neuronal differentiation of neuroblastoma. In contrast, these proteins may promote the growth of rhabdomyosarcoma by suppressing differentiation.

Adolescent↗
PubMed1992

Regional response differences within the human auditory cortex when listening to words.

The relationship between activity within the human auditory cortices and the presentation rate of heard words was investigated by measuring changes in regional cerebral blood flow with positron emission tomography. We demonstrate that in the primary auditory cortices and middle regions of the superior temporal gyri there is a linear relationship between the rate of presentation of heard words and blood flow response. In contrast, the blood flow response in an area of the left posterior superior temporal gyrus (Wernicke's area) is primarily dependent on the occurrence of words irrespective of their rate of presentation. The primary auditory cortices are associated with the early processing of complex acoustic signals whereas Wernicke's area is associated with the comprehension of heard words. This study demonstrates for the first time that time dependent sensory signals (heard words) detected in the primary auditory cortices are transformed into a time invariant output which is channelled to a functionally specialised region--Wernicke's area. Wernicke's area is therefore distinguished from other areas of the auditory cortex by direct observation of signal transformation rather than by association with a specific behavioural task.

Adult↗