"What" and "how": evidence for the dissociation of object knowledge and mechanical problem-solving skills in the human brain

Patients with profound semantic deterioration resulting from temporal lobe atrophy have been reported to use many real objects appropriately. Does this preserved ability reflect (i) a separate component of the conceptual knowledge system ("action semantics") or (ii) the operation of a system that is independent of conceptual knowledge of specific objects, and rather is responsible for general mechanical problem-solving skills, triggered by object affordances? We contrast the performance of three patients-two with semantic dementia and focal temporal lobe atrophy and the third with corticobasal degeneration and biparietal atrophy-on tests of real object identification and usage, picture-based tests of functional semantic knowledge, and a task requiring selection and use of novel tools. The patient with corticobasal degeneration showed poor novel tool selection and impaired use of real objects, despite near normal semantic knowledge of the same objects' functions. The patients with semantic dementia had the expected deficit in object identification and functional semantics, but achieved flawless and effortless performance on the novel tool task. Their attempts to use this same mechanical problem-solving ability to deduce (sometimes successfully but often incorrectly) the use of the real objects provide no support for the hypothesis of a separate action-semantic system. Although the temporal lobe system clearly is necessary to identify "what" an object is, we suggest that sensory inputs to a parietal "how" system can trigger the use of objects without reference to object-specific conceptual knowledge.

Evidence for impaired sentence comprehension in early Alzheimer's disease

We investigated sentence comprehension in 46 patients with probable minimal (very mild), mild, or moderate dementia of the Alzheimer type (DAT), comparing their performance on the Test for the Reception of Grammar (TROG), with that of 20 age- and education-matched controls. Performance on the TROG was generally related to dementia severity, independent of lexicosemantic and working memory (digit span) impairments, but related to at least 1 measure of attention. Some patients in the minimal group showed sentence comprehension deficits while others in the moderate group did not, indicating that DAT may impair sentence comprehension at the very earliest stages of disease, but that its effects are heterogeneous. Patients were most impaired on sentences with 2 propositions and noncanonical word order, suggesting difficulties with both interpretative and postinterpretative stages of sentence processing. Further investigation is needed into the relationship between attentional processes, interpretative and postinterpretative stages of syntactic processing in DAT.

Relearning and subsequent forgetting of semantic category exemplars in a case of semantic dementia

Over 15 months of longitudinal assessment, a patient with semantic dementia, D.M., improved on tests of naming and category fluency for a specific set of items (Experiment 1). The authors attribute this to his home drill with the names of these concepts plus pictures and descriptions of them. In Experiment 2, D.M. produced significantly more exemplars on category fluency for semantic categories that he had been practicing at home than for nonpracticed categories, an effect that cannot be attributed to an inherent difference between the 2 sets because the fluency performance of control participants revealed no significant difference between the 2 sets. In Experiment 3, D.M. rehearsed some of his previously nonpracticed categories daily for a period of 2 weeks: His fluency scores on the experimental categories improved substantially, but they declined once he ceased the daily drill. The results are discussed with respect to current views of long-term memory, particularly new word learning and forgetting, and to current techniques for facilitating word finding in aphasia.

The differentiation of semantic dementia and frontal lobe dementia (temporal and frontal variants of frontotemporal dementia) from early Alzheimer's disease: a comparative neuropsychological study

The authors compared age-matched groups of patients with the frontal and temporal lobe variants of frontotemporal dementia (FTD; dementia of frontal type [DFT] and semantic dementia), early Alzheimer's disease (AD), and normal controls (n = 9 per group) on a comprehensive neuropsychological battery. A distinct profile emerged for each group: Those with AD showed a severe deficit in episodic memory with more subtle, but significant, impairments in semantic memory and visuospatial skills; patients with semantic dementia showed the previously documented picture of isolated, but profound, semantic memory breakdown with anomia and surface dyslexia but were indistinguishable from the AD group on a test of story recall; and the DFT group were the least impaired and showed mild deficits in episodic memory and verbal fluency but normal semantic memory. The frontal and temporal presentations of FTD are clearly separable from each other and from early AD.

Renal cell carcinoma in children with diffuse cystic hyperplasia of the kidneys

We report the clinical, pathologic, and genetic features of renal malignancy in two children with diffuse cystic hyperplasia. Both presented with massive bilateral nephromegaly. Neither had a family history or clinical findings suggestive of tuberous sclerosis or von Hippel-Lindau disease. The kidneys of both children were extensively replaced by tubulocystic hyperplasia with large eosinophilic epithelial cells. The masses of hyperplastic tissue were nodular, compressing remnants of uninvolved renal parenchyma. Tubulopapillary carcinoma was present in both children, one of whom had bilateral multicentric carcinoma. No loss of heterozygosity was detected in the tumors at the TSC1, TSC2, or VHL gene regions, and no alterations in the VHL gene were detected using single-strand conformation polymorphism analysis. These cases of bilateral renal enlargement with diffuse cystic hyperplasia appear to represent a new clinical syndrome that may warrant bilateral nephrectomy because of the risk of malignancy.

A multi-institutional retrospective study of intracranial ependymoma in children: identification of risk factors

PURPOSE

The goal of this multi-institutional retrospective study of children with intracranial ependymoma was to identify risk factors associated with unfavorable overall survival (OS) and event-free survival (EFS).

PATIENTS AND METHODS

Clinical data, including demographics, tumor location, spread, histology, details of surgery, radiation treatment, and chemotherapy were collected. Clinical characteristics and univariate and multivariate analyses of risk factors for OS and EFS are presented.

RESULTS

Eleven U.S. institutions contributed 83 patients treated from 1987 to 1991. The OS at 5 and 7 years was 57% and 46%, and EFS at 5 and 7 years was 42% and 33%. Patients 3 years of age or younger differed from the older group by more common infratentorial location, less common gross total resection (GTR), and postoperative use of chemotherapy rather than radiation. This younger group of patients had worse survival (P < 0.01) than the older age group. Other than young age, less than GTR and World Health Organization (WHO) II grade 3 histology were significant adverse risk factors for EFS in univariate and multivariate analyses. OS shared the same adverse risk factors except for histology in multivariate analysis, which was only of borderline significance (P = 0.05). Progression at the original tumor location, present in 89% of patients, was the major pattern of tumor recurrence. Adjuvant chemotherapy in the group older than 3 years or craniospinal radiation in M0 patients did not significantly change EFS.

CONCLUSIONS

Adverse outcome in childhood intracranial ependymoma is related to age (3 years or younger), histology (grade 3), and degree of surgical resection (less than GTR). New approaches, particularly for local tumor control in younger patients, are needed to improve survival.

Identification of the t(15;17) in AML FAB types other than M3: evaluation of the role of molecular screening for the PML/RARalpha rearrangement in newly diagnosed AML. The Medical Research Council (MRC) Adult Leukaemia Working Party

Acute promyelocytic leukaemia (APL) is characterized by the t(15;17) leading to the formation of PML-RARalpha and RARalpha-PML fusion genes; this rearrangement has been considered both diagnostic for, and restricted to, this subtype of acute myeloid leukaemia (AML FAB M3). We describe two cases of AML with the t(15;17) associated with a PML/RARalpha rearrangement which lacked typical APL morphology, classified as FAB M1 and M2 respectively. In both cases morphological review revealed small populations of cells which exhibited some features associated with APL. In the case classified as M1, PML immunofluorescence studies revealed the classic microparticulate nuclear staining pattern as observed in typical cases of APL with the t(15;17). Similarly, blasts from this case were found to be sensitive to ATRA in vitro as determined by NBT reduction test and by normalization of the PML nuclear body staining pattern. To determine the frequency of PML/RARalpha rearrangements in FAB subtypes other than M3, 530 patients from the MRC AML trials were screened using nested RT-PCR. Only one individual, initially classified as M5 with a normal karyotype, was found to have a PML/RARalpha rearrangement. The diagnosis was revised to M3 variant on subsequent morphological review. In conclusion, this study demonstrates that, in rare cases, the t(15;17) is not restricted to patients with M3 morphology as defined by current FAB criteria. Therefore, although we consider cytogenetic analysis of newly diagnosed cases of AML to be mandatory, our data suggests that routine molecular screening for PML/RARalpha rearrangements is not justified and should be reserved for those cases displaying features which may be suspicious of APL even if such cells comprise only a minority of the total population.

Episodic memory: new insights from the study of semantic dementia

The study of patients with semantic dementia, the temporal variant of frontotemporal dementia, has provided new insights into the interaction between episodic and semantic memory, and the different roles played by various structures in the temporal lobe. Recent findings indicate that the syndrome of semantic dementia can inform us about the organisation of long-term memory and the relationship between semantic memory and other cognitive systems.

Selective disorders of reading?

Over the past few decades, refined cognitive architectures with highly specific components have been proposed to explain apparently selective disorders of reading, resulting from brain disease or injury, in previously literate adults. Recent analysis of the more general linguistic and cognitive abilities supported by neural systems damaged in the various forms of alexia favours a rather different view of reading and the kinds of models sufficient to account for its acquisition, skilled performance and disruption.

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.

Myotonic dystrophy and progressive cognitive decline: a common condition or two separate problems?

We report the case of NG, a 43-year old woman with myotonic dystrophy (MYD) who has shown a slow decline in both motor and cognitive abilities since her referral to us at age 32. MYD is an autosomal dominant disorder characterised by weakening and wasting of the muscles together with impaired muscle relaxation. Cognitive abilities are usually little affected in the adult onset form, although there is a high risk of cognitive impairment in those with childhood onset. Cognitive decline is also typically associated with maternal inheritance. NG, who was diagnosed with MYD at the age of 18, inherited it from her father. We report the decline in NG's cognitive abilities over 11 years of longitudinal assessment, and consider whether she is an atypical MYD patient or whether the MYD and cognitive decline are attributable to two separate pathological processes.

The differentiation of semantic dementia and frontal lobe dementia (temporal and frontal variants of frontotemporal dementia) from early Alzheimer's disease: a comparative neuropsychological study

The authors compared age-matched groups of patients with the frontal and temporal lobe variants of frontotemporal dementia (FTD; dementia of frontal type [DFT] and semantic dementia), early Alzheimer's disease (AD), and normal controls (n = 9 per group) on a comprehensive neuropsychological battery. A distinct profile emerged for each group: Those with AD showed a severe deficit in episodic memory with more subtle, but significant, impairments in semantic memory and visuospatial skills; patients with semantic dementia showed the previously documented picture of isolated, but profound, semantic memory breakdown with anomia and surface dyslexia but were indistinguishable from the AD group on a test of story recall; and the DFT group were the least impaired and showed mild deficits in episodic memory and verbal fluency but normal semantic memory. The frontal and temporal presentations of FTD are clearly separable from each other and from early AD.

Disrupted temporal lobe connections in semantic dementia

Semantic dementia refers to the variant of frontotemporal dementia in which there is progressive semantic deterioration and anomia in the face of relative preservation of other language and cognitive functions. Structural imaging and SPECT studies of such patients have suggested that the site of damage, and by inference the region critical to semantic processing, is the anterolateral temporal lobe, especially on the left. Recent functional imaging studies of normal participants have revealed a network of areas involved in semantic tasks. The present study used PET to examine the consequences of focal damage to the anterolateral temporal cortex for the operation of this semantic network. We measured PET activation associated with a semantic decision task relative to a visual decision task in four patients with semantic dementia compared with six age-matched normal controls. Normals activated a network of regions consistent with previous studies. The patients activated some areas consistently with the normals, including some regions of significant atrophy, but showed substantially reduced activity particularly in the left posterior inferior temporal gyrus (iTG) (Brodmann area 37/19). Voxel-based morphometry, used to identify the regions of structural deficit, revealed significant anterolateral temporal atrophy (especially on the left), but no significant structural damage to the posterior inferior temporal lobe. Other evidence suggests that the left posterior iTG is critically involved in lexical-phonological retrieval: the lack of activation here is consistent with the observation that these patients are all anomic. We conclude that changes in activity in regions distant from the patients' structural damage support the argument that their prominent anomia is due to disrupted temporal lobe connections.

Malignant tumors of the kidney, brain, and soft tissues in children and young adults with the tuberous sclerosis complex

BACKGROUND

The tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterized by seizures, mental retardation, and benign tumors of the brain, heart, skin, and kidney. Malignant tumors also can occur in patients with tuberous sclerosis, particularly in the kidney, although they occur less frequently than benign tumors. The types of malignancy that occur in TSC have not been characterized fully.

METHODS

Clinical and pathologic features of 8 malignant tumors from 6 TSC patients ranging in age from 22 months to 21 years are reviewed. Six tumors were renal, one was from the inguinal region, and one was from the brain. The tumors were analyzed for loss of heterozygosity (LOH) in the chromosomal regions of the TSC1, TSC2, and VHL genes.

RESULTS

Three patients (ages 7, 8, and 20 years) had renal cell carcinomas (RCCs). Two of these patients had multifocal RCCs. All three patients with RCC also had prominent multifocal dysplasia of renal cyst epithelium. Two patients (ages 20 and 21 years) had malignant angiomyolipomas (1 renal and 1 inguinal). One patient (age 22 months) had a Grade 4 giant cell astrocytoma (glioblastoma multiforme). LOH in the region of the TSC2 gene was found, either in the malignant tumor or in benign tumors, in all five patients whose DNA could be analyzed.

CONCLUSIONS

Children with TSC, as well as adults with the disease, are at risk for developing malignant tumors. Two types of renal malignancy occur in TSC: RCC, which appears to arise from dysplastic renal cyst epithelial cells, and malignant angiomyolipoma. Tumors cytologically similar to malignant angiomyolipomas also may occur at extrarenal sites. LOH analyses suggest that the majority of patients with TSC who develop malignant tumors have germline TSC2, rather than TSC1, gene mutations.

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.

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.

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.

The immunohistological diagnosis of E. coli O157:H7 colitis: possible association with colonic ischemia

OBJECTIVE

E. coli O157:H7 may cause hemorrhagic colitis resembling ischemic colitis. Diagnosis is usually made by finding sorbitol-negative colonies on MacConkey agar that react with O157 and H7 antisera. Most ischemic colitis is idiopathic, but some may be caused by E. coli O157:H7, inasmuch as this organism can produce fibrin thrombi in colon vasculature. The objectives of this study were to determine whether E. coli O157:H7 infection can be diagnosed retrospectively from paraffin blocks of colon sections and whether an association exists between E. coli O157:H7 infection and colonic ischemia.

METHODS

Paraffin-embedded sections of normal colon (n = 2) and various colitides [ischemic (n = 11), E. coli O157:H7 (n = 2), IBD (n = 8) and pseudomembranous (n = 3)] were used. Sections were deparaffinized, rehydrated, incubated with 3% peroxide in methanol, rinsed, and incubated with peroxidase-labeled antibody isolated from goats immunized with whole E. coli O157:H7. Sections were stained with peroxidase chromagen reagent and counterstained with hematoxylin. Coarse, granular, orange-brown staining was considered positive. To determine the localization of the chromagen deposits, three cases that stained positive, including one of the culture-proved E. coli O157:H7 colitis and two of colonic ischemia, were processed for electron microscopy.

RESULTS

Both cases (100%) of E. coli O157:H7 colitis and three of 11 (27.3%) cases of ischemic colitis stained positive by light microscopy. In one culture-proved case, electron microscopy demonstrated staining of bacillary structures; in two cases of colonic ischemia, extensive deposits of chromagen material were present that were associated neither with inflammatory cells nor with bacterial forms.

CONCLUSIONS

Immunoperoxidase staining of archival sections may be used to diagnose E. coli O157:H7 infection. An etiological role for this organism is possible in some cases of colonic ischemia.

Substrate use during and following moderate- and low-intensity exercise: implications for weight control

Substrate utilization during and after low- and moderate-intensity exercise of similar caloric expenditure was compared. Ten active males [age: 26.9 (4.8) years; height: 181.1 (4.8) cm; Mass: 75.7 (8.8) kg; maximum O2 consumption (VO2max): 51.2 (4.8) ml x kg(-1) x min(-1)] cycled at 33% and 66% VO2max on separate days for 90 and 45 min, respectively. After exercise, subjects rested in a recumbent position for 6 h. Two h post-exercise, subjects ate a standard meal of 66% carbohydrate (CHO), 11% protein, and 23% fat. Near-continuous indirect calorimetry and measurement of urinary nitrogen excretion were used to determine substrate utilization. Total caloric expenditure was similar for the two trials; however, significantly (P < 0.05) more fat [42.4 (3.6) g versus 24.0 (12.2) g] and less CHO [142.5 (28.5) g versus 188.8 (45.2) g] was utilized as a substrate during the low-intensity compared to the moderate-intensity trial. Protein utilization was similar for the two trials. The difference in substrate use can be attributed to the exercise period because over twice as much fat was utilized during low-intensity [30.0 (11.0) g] compared to moderate-intensity exercise [13.6 (6.6) g]. Significantly more (P < 0.05) CHO was utilized during the moderate-intensity [106.0 (27.8) g] compared to the low-intensity exercise [68.7 (20.0) g]. Substrate use during the recovery period was not significantly different. We conclude that low-intensity, long-duration exercise results in a greater total fat oxidation than does moderate intensity exercise of similar caloric expenditure. Dietary-induced thermogenesis was not different for the two trials.

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.

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.

Category specific semantic loss in dementia of Alzheimer's type. Functional-anatomical correlations from cross-sectional analyses

In the context of focal brain injury, selective loss of semantic knowledge in the domain of either natural kinds or artefacts is usually considered to reflect the differential importance of temporal and frontoparietal regions to the representations of perceptual and functional attributes, respectively. It is harder to account far as a feature of a more diffuse process, and previous cross-sectional analyses of patients with dementia of Alzheimer's type (DAT) have differed over whether category effects occur. In our series of 58 patients with probable DAT, we demonstrated a significant group advantage for artefacts, and explored possible reasons for the inconsistency of this finding in other studies. A multiple single-case strategy revealed not only individuals with consistent advantages for artefacts but also individuals with consistent advantages for natural kinds. By ranking the individuals according to measures of naming performance and global intellectual ability, we showed that the strength of the group advantage for artefacts was dependent on the former but not the latter variable. The findings are discussed in the context of two competing theories of semantic breakdown in DAT. One differentiates between domains of knowledge in terms of the structure of semantic representations within a single distributed network; the other emphasizes the importance of different brain regions in the category distinction. We conclude that our findings are in keeping with the predictions of the latter hypothesis.

Single word production in nonfluent progressive aphasia

We present an experiment investigation of the spoken single word production of two patients with nonfluent progressive aphasia. In Experiment 1, a task effect (reading > repetition > naming) suggested that phonological information available from task stimuli facilitated the patients' speech production; a length effect reflected the increased difficulty of phonological processing required for long words compared with that required for shorter words. Experiment 2 compared repetition, reading, copying, and writing to dictation tasks and demonstrated that a correspondence between input and output modality also facilitated performance. Experiment 3 showed that the patients' access to appropriate phonology in reading was positively related to the degree of correlation between orthographic and phonological forms. These results are discussed with reference to an account of pathologically weakened connections between nodes in an interactive spreading activation model of speech production of the type described by Dell (1986).

Word reading in Alzheimer's disease: cross-sectional and longitudinal analyses of response time and accuracy data

Using a list of high- and low-frequency regular and exception words, we measured the reading performance of three groups of subjects: patients with mild dementia of the Alzheimer's type (DAT) at presentation (Stage 1) and 2-3 years later (Stage 2); moderately severe DAT patients; and control subjects. In the longitudinally studied patients, there was a dramatic increase in response times (RTs) from Stage 1 to Stage 2, but little change in either error rate or pattern. By contrast, a comparison of the Stage 2 with the Moderate patients revealed similar RTs but a significant increase in error rate for the Moderate group, particularly on low-frequency exception words. These two results for word naming were almost exactly mirrored by effects in picture naming. We conclude that correct word reading, especially for less common words with atypical spelling-sound correspondences, is compromised in DAT only when the disease produces a significant deterioration of semantic memory. These results are relevant to current theories about normal and impaired reading processes.

Histiocytoid cardiomyopathy: three new cases and a review of the literature

Histiocytoid cardiomyopathy (HC), a rare arrhythmogenic disorder, presents as difficult-to-control arrhythmias or sudden death in infants and children, particularly girls. Three cases are described with autopsy findings. In two cases, yellow-tan nodules were grossly visible in the myocardium; in the third case, no gross lesions were identified. Microscopic examination in all three cases revealed multiple, scattered clusters of histiocytoid myocytes which on ultrastructural examination were filled with abnormal mitochondria, scattered lipid droplets, and scanty myofibrils. These pathologic findings are similar to those previously described. The pathogenesis of this entity remains controversial. It was recently proposed that this disorder is X-linked dominant with the associated gene located in the region of Xp22.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.