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R Duara

Publications and source records attributed to R Duara.

119 records · Page 7Linked to original sources
PubMed1984

Intercorrelations of glucose metabolic rates between brain regions: application to healthy males in a state of reduced sensory input.

We use a correlational analysis of regional metabolic rates to characterize relations among different brain regions. Starting with rates of local glucose metabolism (rCMRglc) obtained by positron emission tomography using [18F]fluorodeoxyglucose, we propose that the strength of the association is proportional to the magnitude of the correlation coefficient. Partial correlation coefficients, controlling for whole brain glucose metabolism, are used in the analysis. We also introduce a graphical technique to display simultaneously all the correlations, allowing us to examine patterns of relations among them. The method was applied to 40 very healthy males under conditions of reduced auditory and visual inputs (the "resting state"). Dividing the brain into 59 regions, and keeping only those partial correlation coefficients significant to p less than 0.01, we found the following: (a) All regions were significantly correlated with their contralateral homologues. For the most part, the largest partial correlation coefficients were between homologous brain regions. (b) Generally, the pattern of significant correlations between any two lobes in the left hemisphere did not differ statistically from the corresponding pattern in the right hemisphere. (c) Strong correlations were observed between primary somatosensory areas and premotor association areas. Correlations between these association areas and primary visual and auditory regions were not statistically significant. (d) Significant correlations between inferior occipital and temporal areas were found. Metabolic rates in the superior part of the occipital lobe were not correlated significantly with metabolic rates in regions of the temporal lobe, nor with metabolism in the parietal lobe. (e) As a whole, there were numerous correlations among frontal and parietal lobe regions, on the one hand, and among temporal and occipital lobe regions, on the other, but few statistically significant correlations between these two domains. We relate our results to various aspects of known brain anatomy, physiology, and cognitive functioning.

Acoustic Stimulation↗
PubMed1984

NIH Conference. Brain imaging: aging and dementia.

The brain imaging techniques of positron emission tomography using [18F]-fluoro-2-deoxy-D-glucose, and computed tomography, together with neuropsychological tests, were used to examine overall brain function and anatomy in three study populations: healthy men at different ages, patients with presumptive Alzheimer's disease, and adults with Down's syndrome. Brain glucose use did not differ with age, whereas an age-related decrement in gray matter volume was found on computed tomographic assessment in healthy subjects. Memory deficits were found to precede significant reductions in brain glucose utilization in mild to moderate Alzheimer's dementia. Furthermore, differences between language and visuoconstructive impairments in patients with mild to moderate Alzheimer's disease were related to hemispheric asymmetry of brain metabolism. Brain glucose utilization was found to be significantly elevated in young adults with Down's syndrome, compared with controls. The importance of establishing strict criteria for selecting control subjects and patients is explained in relation to the findings.

Adult↗
PubMed1984

Auditory brainstem responses in pervasive developmental disorders.

Several studies have reported prolonged neural transmission times on auditory brainstem responses (ABRs) measured in autistic children, a finding which implicates CNS dysfunction at the level of the brainstem in autistic conditions. This study measured ABRs in 25 children and adults with pervasive developmental disorders (PDDs), including autism, and 25 age- and sex-matched normal controls. Subjects were carefully evaluated audiometrically and neurologically and artifact was controlled to produce highly reliable measures. Prolonged transmission times were seen in only one PDD subject and in one normal control, while shortened transmission times were seen in four PDD subjects. The majority of PDD subjects showed normal ABRs. Previous reports of a significant incidence of prolonged transmission times among autistic and autisticlike subjects, thus, were not replicated. Possible reasons for this discrepancy are discussed.

Adolescent↗
PubMed1983

Down's syndrome in adults: brain metabolism.

The cerebral metabolic rate for glucose, as measured with positron emission tomography and fluorine-18-labeled 2-deoxy-D-glucose, was significantly higher in four healthy young subjects with trisomy 21 syndrome (Down's syndrome) than the mean rate in healthy young controls. The rate of cerebral glucose utilization in the frontal lobe of a 51-year-old subject with Down's syndrome was significantly lower than the rate in the young subjects with this syndrome, but approximated the rate in middle-aged controls. Thus glucose utilization by the brain appears to be excessive in young adults with Down's syndrome but may decline with age in some brain regions.

Adult↗
PubMed1983

Cerebral glucose utilization, as measured with positron emission tomography in 21 resting healthy men between the ages of 21 and 83 years.

Positron emission tomography (PET) scanning with 18F-2-deoxy-D-glucose was employed to examine hemispheric and regional rates of cerebral glucose utilization in 21 resting healthy men between the ages of 21 and 83 years. The eyes of the subjects were covered and the external auditory canals were plugged with cotton in the 45 minutes following injection of tracer. Mean hemispheric cerebral metabolic rates for glucose (CMRglc) averaged 4.3 to 4.4 mg x 100 g-1 X min-1, and mean hemispheric grey matter glucose utilization, (CMRglc)grey, averaged 5.2 to 5.3 mg x 100 g-1 X min-1. Neither parameter was correlated significantly with age, nor were their right/left ratios correlated with age (P greater than 0.05). The mean ratios, furthermore, did not differ significantly from 1. Regional cerebral metabolic rates for glucose, rCMRglc, at each of 31 identified midline and bilateral structures also were not correlated significantly with age. Mean rCMRglc ranged from 2.6 mg X 100 g-1 X min-1 at the centrum semiovale to 6.2 mg . 100 g-1 X min-1 at the precentral gyrus of the frontal lobe and precuneus of the parietal lobe. The results indicate that the cerebral metabolic rate for glucose is not correlated with age in healthy men.

Adult↗
PubMedDate not supplied

Spastic paraplegia with iron deposits in the basal ganglia: a new X-linked mental retardation syndrome.

We report on a family with X-linked mental retardation (XLMR) and severe spastic paraplegia. Appearance is normal but there is severe involvement of the lower limbs (affected relatives never walked), with minimal involvement of the upper limbs and unusual MRI findings including macrogyria, white matter hypoplasia, lack of myelination and a markedly increased paramagnetic signal suggestive of iron deposition. Linkage studies documented possible linkage, with no recombination, between the disease locus and DXS424. A 7-point linkage analysis yielded a maximum LOD score of 1.9, (theta = 0.00) for three loci spanning Xq22-q25. The combination of the unusual clinical and MRI findings and the tentative localization to a region different than other XLMR syndromes with spastic paraplegia, provide good evidence that this is a new XLMR syndrome.

Adult↗
PubMedDate not supplied

MR signal abnormalities in memory disorder and dementia.

MR imaging of the brain, performed in 86 normal subjects and 113 patients with objective memory disorder or dementia, demonstrated white- and gray-matter areas of high signal intensity on long TR images (short and long TE). Hyperintensities were analyzed with respect to size (on a scale of 0-3) and location: lesions were periventricular, subcortical, or cortical. The patients with memory disorder and dementia were categorized as having probable/possible Alzheimer disease, a combination of Alzheimer disease and multiinfarct cognitive disorder, or multiinfarct cognitive disorder alone on the basis of clinically determined Hachinski ischemic scores. Significant correlations were found between age and scores for periventricular lesions (r = .40, p less than .0005) and subcortical lesions (r = .39, p less than .0005) in normal subjects. Correlations were also found between the Hachinski ischemic score and scores for periventricular lesions (r = .21, p less than .01), subcortical lesions (r = .27, p less than .0002), and cortical lesions (r = .32, p less than .0005) in subjects with memory disorder/dementia. Comparing multiinfarct cognitive disorder, Alzheimer disease, and normal groups, the mean scores for periventricular lesions were 12.0 +/- 4.6, 7.6 +/- 4.8, and 3.4 +/- 2.6, while mean scores for subcortical lesions were 10.8 +/- 12.2, 4.1 +/- 6.4, and 0.8 +/- 1.2, respectively. Periventricular lesions were present in 99-100% of patients with Alzheimer disease and multiinfarct cognitive disorder. On the other hand, subcortical lesions, which were identified in 100% of patients with multiinfarct cognitive disorder, were present in only about half of the patients with Alzheimer disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗