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K Patterson

Publications and source records attributed to K Patterson.

At least 73 records · Page 4Linked to original sources
PubMed1998

A functional neuroimaging description of two deep dyslexic patients.

Deep dyslexia is a striking reading disorder that results from left-hemisphere brain damage and is characterized by semantic errors in reading single words aloud (e.g., reading 'spirit' as 'whisky'). Two types of explanation for this syndrome have been advanced. One is that deep dyslexia results from a residual left-hemisphere reading system that has lost the ability to pronounce a printed word without reference to meaning. The second is that deep dyslexia reflects right-hemisphere word processing. Although previous attempts to adjudicate between these hypotheses have been inconclusive, the controversy can now be addressed by mapping functional anatomy. In this study, we demonstrate that reading by two deep dyslexic patients (CJ and JG) involves normal or enhanced activity in spared left-hemisphere regions associated with naming (Broca's area and the left posterior inferior temporal cortex) and with the meanings of words (the left posterior temporo-parietal cortex and the left anterior temporal cortex). In the right-hemisphere homologues of these regions, there was inconsistent activation within the normal group and between the deep dyslexic patients. One (CJ) showed enhanced activity (relative to the normals) in the right anterior inferior temporal cortex, the other (JG) in the right Broca's area, and both in the right frontal operculum. Although these differential right-hemisphere activations may have influenced the reading behavior of the patients, their activation patterns primarily reflect semantic and phonological systems in spared regions of the left hemisphere. These results preclude an explanation of deep dyslexia in terms of purely right-hemisphere word processing.

Brain Mapping↗
PubMed1998

Functional neuroanatomy of the semantic system: divisible by what?

Studies of patients with brain damage suggest that specific brain regions may be differentially involved in representing/processing certain categories of conceptual knowledge. With regard to the dissociation that has received the most attention--between the domains of living things and artifacts--a debate continues as to whether these category-specific effects reflect neural implementation of categories directly or some more basic properties of brain organization. The present positron emission tomography (PET) study addressed this issue by probing explicitly for differential activation associated with written names of objects from the domains of living things or artifacts during similarity judgments about different attributes of these objects. Subjects viewed triads of written object names and selected one of two response words as more similar to a target word according to a specified perceptual attribute (typical color of the objects) or an associative attribute (typical location of the objects). The control task required a similarity judgment about the number of syllables in the target and response words. All tasks were performed under two different stimulus conditions: names of living things and names of artifacts. Judgments for both domains and both attribute types activated an extensive, distributed, left-hemisphere semantic system, but showed some differential activation-particularly as a function of attribute type. The left temporo-occipito-parietal junction showed enhanced activity for judgments about object location, whereas the left anteromedial temporal cortex and caudate nucleus were differentially activated by color judgments. Smaller differences were seen for living and nonliving domains, the positive findings being largely consistent with previous studies using objects; in particular, words denoting artifacts produced enhanced activation in the left posterior middle temporal gyrus. These results suggest that, within a distributed conceptual system activated by words, the more prominent neural distinction relates to type of attribute.

Adult↗
PubMed1998

Prevalence of diabetes mellitus and obesity in the Keewatin District of the Canadian Arctic.

Through a medical chart review, the prevalence of diagnosed diabetes mellitus in Inuit of the Keewatin District of the Canadian Northwest Territories was determined to be 0.27%. All cases were in adults, and no cases of gestational diabetes were noted. The prevalence and pattern of obesity were determined from measurements of body mass index (BMI), skinfold thickness, and waist-hip ratio obtained during the 1990-91 Keewatin Health Assessment Study. Thirty-one percent of 414 randomly identified adults (29% of men, 37% of women) were overweight (BMI > 27). Central fat patterning was more prevalent in women and less prevalent in men from the Keewatin compared to the general Canadian population. Comparison of skinfold thickness values to published measurements obtained from earlier arctic surveys supports the hypothesis that changes in diet and activity levels associated with urbanization have resulted in increased obesity in the Inuit.

Adolescent↗
PubMed1998

The pathologic handling of skeletal tumors.

Because bone harbors a wide variety of benign and malignant pathologic entities, most of which are uncommon, pathologists feel uneasy when faced with many of these lesions. Accurate diagnoses of these lesions require correlation of the radiologic and clinical findings with the pathologic features. At the time of biopsy, placing a lesion into one of five pathologic groups based on the predominant cell or matrix type present (osteoid, chondroid, giant cell, fibrous, small cell) aids in analyzing the specimen. Current management of malignant bone tumors includes diagnosis on often tiny biopsy samples followed by preoperative chemotherapy and finally limb-sparing resection of the involved bone. Adequate evaluation of these resections requires extensive examination with grading of the tumor necrosis and careful attention to the resection margins.

Adolescent↗
PubMed1998

Gln368STOP myocilin mutation in families with late-onset primary open-angle glaucoma.

PURPOSE: To examine families ascertained for late-onset primary open-angle glaucoma (POAG) to determine mutations in the gene coding for myocilin. METHODS: The diagnosis of late-onset POAG was defined as age at diagnosis more than 35 years, intraocular pressure (IOP) 22 mm Hg or more in both eyes or 19 mm Hg or more while the patient was taking two glaucoma medications, glaucomatous optic neuropathy in both eyes, and visual field loss consistent with optic nerve damage in at least one eye of the proband. Two of three criteria were required in other family members. DNA from all families was screened for polymorphisms in myocilin using single-strand conformation polymorphism analysis. All polymorphisms were sequenced for mutations. RESULTS: Eighty-three affected people in 29 families with late-onset POAG were screened for mutations. Three mutations, two novel missense (Thr377Met and Glu352Lys) and one nonsense (Gln368STOP), were identified. The missense mutations did not segregate with the disease phenotype in these families. The nonsense mutation was found in 3 of 29 unrelated families with POAG. All affected family members and 8 of 12 in whom glaucoma was suspected had the Gln368STOP mutation. All people with this mutation had elevated IOP, and 78% had POAG by age 70. CONCLUSIONS: Three mutations were identified in the gene coding for myocilin in families with late-onset POAG. Of these, the Gln368STOP mutation was highly associated with the development of glaucoma. All people with this mutation had glaucoma or elevated IOP by age 70. In the United States, the Gln368STOP mutation in myocilin is strongly associated with the development of late-onset POAG. However, factors in addition to the presence of this mutation seem to play a role in the development of ocular hypertension and glaucoma in these families.

Adult↗
PubMed1998

Expression of androgen receptors in nasopharyngeal angiofibroma: an immunohistochemical study of 24 cases.

Angiofibromas are uncommon benign tumors that typically occur in the lateral portion of the nasopharynx of adolescent boys. Numerous reports showed indirect evidence for the presence of sex-hormone receptors, i.e., androgen (AR), estrogen (ER), and progesterone (PR) receptors, in these tumors. The goal of the current study was to show direct evidence of sex hormone receptor expression in angiofibromas with use of sensitive immunocytochemical techniques and to document which cell populations express the receptor. Twenty-four nasopharyngeal angiofibromas were obtained from archived tissue, and immunocytochemical studies were performed with antibodies to AR, PR, and ER. Positive stromal and endothelial nuclear immunostaining, implying the presence of ARs, was seen in 18 (75%) of 24 cases, whereas 2 (8.3%) of 24 cases were positive with antibodies to PR. None of the 24 cases examined was positive with antibodies to ER. These results provide the first direct evidence for the presence of ARs in angiofibromas, which might help to explain the unique clinicopathologic features of these tumors.

Adolescent↗
PubMed1997

The gradual deterioration of syntax and semantics in a patient with progressive aphasia.

FM is a progressive aphasic patient whose language comprehension we studied over a 4-year period. We developed a variety of implicit and explicit tasks to chart progressive changes in the representation of linguistic knowledge (in particular, syntax and semantics) and the automatic and controlled processes which operate on that knowledge. The representation of FM's semantic knowledge remained essentially intact over the years, but she became increasingly impaired at combining the meanings of words. She also showed progressive impairments in the processes of syntactic combination. Thus, FM's disease resulted in a progressive inability to engage in those combinatorial processes necessary for the normal comprehension of a spoken utterance. This is not a selective deficit in the traditional sense of the term, since aspects of both syntax and semantics are implicated; but it is selective in the sense that other aspects of language comprehension remain intact.

Aphasia↗
PubMed1997

Pharmacokinetics of zileuton and its metabolites in patients with renal impairment.

The pharmacokinetics of zileuton and its conjugated metabolites were evaluated in patients with chronic renal impairment. Five healthy volunteers (creatinine clearance > 90 mL/min), five patients with renal failure requiring hemodialysis, six with mild (creatinine clearance, 60-90 mL/min), eight with moderate (creatinine clearance, 30-59 mL/min), and six with severe (creatinine clearance < 30 mL/min) renal impairment participated in the study. Zileuton was well tolerated by all participants including those with severe renal impairment and those receiving hemodialysis. The pharmacokinetics of zileuton were similar in healthy volunteers; in patients with mild, moderate and severe renal impairment; and in patients with renal failure requiring hemodialysis. The mean metabolite/parent-area ratios for the pharmacologically inactive zileuton glucuronides progressively increased with the decline in renal function. A very small percentage of the administered zileuton dose (< 0.5%) was removed by hemodialysis. Therefore, adjustment in the dose regimen of zileuton does not appear to be necessary for patients with various degrees of renal impairment and patients with renal failure requiring hemodialysis.

Adult↗
PubMed1997

Dysgraphia in mild dementia of Alzheimer's type.

We assessed writing abilities in a cohort of 31 patients with a diagnosis of DAT (in two subgroups, with minimal [MMSE 24-28] and mild [MMSE 16-23] levels of dementia), and 10 matched controls. Central aspects of writing were assessed by both written and oral spelling to dictation of 72 single words varying in frequency (high or low) and predictability of sound-to-spelling correspondences (predictable, unpredictable and irregular). All subjects achieved better scores on high, as compared to low, frequency words. The performance of both patient groups was significantly affected by degree of predictability, and was equivalent in the written and oral spelling conditions. Phonologically acceptable alternative spellings (e.g. 'wade'-->WAID) constituted the majority of errors. More peripheral processes in writing were assessed by copying and cross-case transcription of single letters. Subjects were more successful at copying within case than transcribing across case. Performance was also better--substantially so for the mild DAT group--when the target response in either task was an upper- rather than a lower-case letter. There was considerable heterogeneity in performance on the spelling and the letter tasks. Some patients (even in the more affected DAT group) were unimpaired on both tasks, suggesting that dysgraphia is not a constant feature in early DAT. When writing deficits do become apparent, in the earliest stages of the disease the pattern is most likely to be one of mild surface dysgraphia, a form of central dysgraphia; impairments in more peripheral aspects of writing tend to emerge once the disease has progressed beyond the minimal stage.

Aged↗
PubMed1997

The relationship between naming and semantic knowledge for different categories in dementia of Alzheimer's type.

We studied the relationship between naming and semantic memory in a group of 10 patients with dementia of Alzheimer's type. In an extension to a previous cross-sectional study (Hodges, J. R. et al., Brain and Language, 1996, 54, 302-325), this relationship was investigated at two longitudinal points within each patient's cognitive decline. Two types of naming performance were compared: items that each patient named correctly at the first stage but failed to name at the second stage, as contrasted with items named correctly at both stages (thereby providing a control for cognitive decline in general). Semantic knowledge of the concepts represented by the pictures in the naming test was investigated at each stage using definitions to the spoken object name, scored particularly for the number of sensory and associative/functional features provided by the patient. At stage 2, an analysis of the definitions for named-->unnamed items as contrasted with named-->named objects revealed a significant loss of both sensory and associative information. A comparison between natural kinds (animals and birds) and artefacts (household objects, vehicles, etc.), however, demonstrated a striking interaction between category and type of information contained in the definitions. Specifically, stage 2 definitions of artefacts in the named-->unnamed set showed a disproportionate loss of associative/functional information, while definitions of animal names that patients failed to produce in response to the pictures were notably lacking in sensory features. This pattern supports the notion that successful naming relies on a subset of critical semantic features which vary somewhat across different categories of semantic knowledge. We suggest that these findings are best encompassed by a conception of semantic organization, Weighted Overlappingly Organized Features (WOOF), in which (i) knowledge about all objects is represented by a central, distributed network of features activated by both words and pictures, but (ii) natural kinds and artefacts are differentially weighted in favour of those features that are involved in learning about and experiencing different kinds of objects.

Aged↗
PubMed1997

Frequency and consistency effects in a pure surface dyslexic patient.

Data are presented from a neurological patient (M.P.) with an acquired deficit for naming words with atypical spelling-sound correspondences. In Experiment 1, the degree of consistency within neighborhoods of orthographically similar words had a parallel impact on M.P.'s pronunciations of regular and irregular words and nonwords. This result is more compatible with models in which the same basic procedure, sensitive in a graded fashion to both frequency and consistency, computes pronunciations for all types of letter strings than it is with models postulating separate lexical and nonlexical mechanisms. In Experiment 2, both correct and regularized pronunciations of exception words yielded response times significantly modulated by word frequency, a finding not predicted by an current model. Neuropsychological observations provide an important additional source of evidence regarding models of cognitive function.

Dyslexia↗
PubMed1997

D-2-hydroxyglutaric aciduria: hypotonia, cortical blindness, seizures, cardiomyopathy, and cylindrical spirals in skeletal muscle.

An infant girl was demonstrated to have D-2-hydroxyglutaric aciduria, the fifth case described and the first with muscle biopsy of this rare organic aciduria that differs clinically and genetically from the more common L-2-hydroxyglutaric aciduria. Her clinical features included mildly dysmorphic facies, developmental delay, generalized hypotonia, myoclonic seizures, cortical blindness, and dilated cardiomyopathy requiring treatment. Muscle biopsy demonstrated only excessive glycogen histochemically, but ultrastructural examination revealed subsarcolemmal cylindrical spirals and normal mitochondria. Because of the metabolism of D-2-hydroxyglutaric aciduria, we regard valproic acid as contraindicated in the treatment of epilepsy in this disease.

Amino Acid Metabolism, Inborn Errors↗
PubMed1997

Ras oncogene mutations in childhood brain tumors.

Although N-nitroso compounds (NNC) are ubiquitous in the human environment and are known neurocarcinogens in animal models, results of epidemiological studies have not yet convincingly associated NNCs with brain tumor occurrence in humans. Animal studies have suggested that specific codons (12, 13, and 61) in the ras family are mutable by exposure to NNCs. The purpose of this study was to measure the presence of mutations in the ras family of oncogenes in tissue from childhood brain (CB) tumors as a preliminary step toward investigating their potential use as biomarkers of chemical exposure. DNA was extracted from paraffin-embedded formalin-fixed CB tumors from tissues resected during neurosurgical operations. Using the PCR, designed RFLP-screening methods, and sequencing, we attempted to screen brain tumors from 46 children for the presence of H, K, and N-ras mutations at codons 12, 13, and 61. Screening for oncogene mutations using PCR, RFLP methods, and DNA sequencing was successfully completed for a high proportion of the available specimens. Astrocytoma specimens from three children for whom screening with PCR was successfully completed were found to contain CAA-->GAA point mutations in K-ras at codon 61. None of the specimens contained mutations at any of the other locations. These results, although preliminary, provide a potential clue for future mechanistic studies of CB tumors. The possible roles of NNCs in inducing this mutation, or of this mutation as an early or late event in tumor progression, however, remain unclear.

Adolescent↗
PubMed1997

Antibodies to desmin identify the blastemal component of nephroblastoma.

The blastemal component of Wilms' tumor (WT) might be indistinguishable histologically from other small, blue, round-cell tumors of childhood, including alveolar rhabdomyosarcoma (RMS), particularly in small biopsy specimens and in the setting of metastatic disease. Furthermore, there are currently no reliable blastemal markers. Deparaffinized sections of 9 formalin-fixed blastema-predominant WTs and 46 RMSs were immunostained with antibodies to desmin (D33), myogenin (F5D), MyoD1 (5.8A), and muscle-specific actins (HHF35), after heat-induced epitope retrieval. WE defined as positive those cases with more than 5% of cells immunostained (only nuclear staining was considered as positive for myogenin and MyoD1). Antibodies to desmin were positive in eight (89%) of nine cases of blastema-predominant WT; in contrast, no case was positive for any of the other muscle-associated proteins. Of the 46 cases of RMS, all were positive for desmin, 42 were positive for myogenin and MyoD1, and 43 were positive for muscle actins. Desmin immunoreactivity, of and by itself, cannot be considered specific for RMS, but when accompanied by immunoreactivity for other myogenic proteins, it is highly characteristic of RMS. Our data also suggest that desmin immunoreactivity, in the absence of other muscle-associated protein expression, might be considered a clue to the diagnosis of the blastemal WT. Particularly in the context of small biopsy specimens or in metastatic settings, the use of a panel of antibodies to desmin as well as to other myogenic proteins, such as MyoD1 or myogenin, can help to discriminate between WT and RMS. Additional studies are required to determine whether desmin immunoreactivity in the blastemal component of WT represents true desmin expression.

Actins↗
PubMed1996

Generating 'tiger' as an animal name or a word beginning with T: differences in brain activation.

Positron emission tomography was used to investigate differences in regional cerebral activity during word retrieval in response to different prompts. The contrast of semantic category fluency and initial letter fluency resulted in selective activation of left temporal regions; the reverse contrast yielded activation in left frontal regions (BA44/6). A further comparison between types of category fluency demonstrated a more anterior temporal response for natural kinds and more posterior activation for manipulable manmade objects. These results support behavioural data suggesting that category fluency is relatively more dependent on temporal-lobe regions, and initial letter fluency on frontal structures; and that categorical word retrieval is not a uniformly distributed function within the brain. This is compatible with the category-specific deficits observed after some focal lesions.

Adult↗
PubMed1996

Alzheimer disease and nonfluent progressive aphasia.

OBJECTIVE: To describe a patient with pathologically proven Alzheimer disease (AD) who presented with a non-fluent progressive aphasic syndrome. DESIGN: Longitudinal neuropsychological assessment, structural (magnetic resonance imaging) and functional (single photon emission computed tomography) imaging, and postmortem brain examination. SETTING: Memory and cognitive disorders clinic in a tertiary referral hospital. PATIENT: A 66-year-old man presented with a 5-year history of progressive nonfluent aphasia characterized by marked deficits in phonology and syntax with preservation of everyday abilities. His condition deteriorated rapidly and he died suddenly of a myocardial infarction 12 months later. RESULTS: Neuropsychological testing revealed mild global intellectual impairment with marked impairment of auditory verbal short-term memory, syntactic, and phonological abilities. His naming errors were predominantly phonological paraphasias. Magnetic resonance imaging scans showed left perisylvian atrophy and results of a Tc 99m hexamethyl-propyleneamine-oxime single photon emission computed tomographic scan were normal. Postmortem pathological examination revealed typical AD pathological features with atypical distribution, involving predominantly perisylvian language areas, but sparing the medial temporal lobe. CONCLUSIONS: The language deficits in AD, which have received considerable attention, are thought to involve predominantly lexicosemantic processes. When AD presents as a relatively isolated language disturbance, the aphasia is usually of the fluent anomic type. To our knowledge, our patient represents the first fully documented case of progressive nonfluent aphasia with pathologically verified AD.

Aged↗