Biomedical subjects

Y Terayama

Publications and source records attributed to Y Terayama.

At least 37 records · Page 2Linked to original sources

PubMed1996

[A case of Paget's disease with progressive sensorineural hearing loss involved in the bilateral bony labyrinths].

Paget's disease of the bone is a chronic, progressive disease of unknown etiology characterized by abnormal bony resorption and deposition. It is a common skeletal disease in Europe and North America, while in Japan it is very rare. Paget's disease of the temporal bone has been reported to cause hearing loss frequently. We report a 50-year-old woman with Paget's disease who had progressive bilateral sensorineural hearing loss and right vestibular dysfunction. CT and 3 Dimensional CT (3D-CT) images demonstrated resorption of the entire bony labyrinth and its surroundings on both sides and that the temporal bone elsewhere remained intact. Bone scans revealed disease symmetrically in the bilateral otic capsules. Previous studies indicated that the bone changes in Paget's disease in the petrous pyramid begin in areas best supplied with marrow tissue and that the otic capsule is relatively spared until advanced changes are present in the remainder of the petrous pyramid. But, this patient mainly had foci in the bilateral otic capsules and the pattern was similar to cochlear otosclerosis. 3D-CT was useful for differentiation of Paget's disease and cochlear otosclerosis. The pattern of the affected areas indicated that this is a very rare situation even in the reports of Europe and North America, where the disease is rather common.

Diagnosis, Differential↗

PubMed1996

[Estimation of catecholamine release based on dialyzer clearance rate during hemodialysis].

To estimate catecholamine (CA) release during hemodialysis (HD), plasma-free and conjugated CAs and their dialyzer clearance rates were measured in 10 HD patients (age; 49.8 +/- 15.2 years, duration of HD; 5.8 +/- 5.0 years). Although free dopamine (f-DA) and all conjugated CAs decreased to about one half of the pre-HD levels at the end of HD, no significant change was seen in free norepinephrine (f-NE) and epinephrine (f-E) during HD. For every CA, the clearance rate was the highest in the sulfate and the lowest in the glucuronide form, and NE was the highest in every form. In the comparison between the measured CA and calculated CA using the clearance rate and the pre-HD level, the measured values of f-NE and f-E were significantly higher than the calculated values, unlike the results for f-DA and conjugated CAs. The difference in f-NE between the measured and the calculated values correlated negatively with the change in mean blood pressure (delta MBP), and delta MBP was also correlated with the ultrafiltration volume. From these data, it was suggested that f-NE was released by the decrease of MBP due to the increase of ultra-filtration volume during HD.

Adult↗

PubMed1995

Activated leukocytes, endothelial cells, and effects of pentoxifylline: observations by VEC-DIC microscopy.

Using video-enhanced contrast (VEC)-differential interference contrast (DIC) microscopy, ultrastructural observations were made of the activation of polymorphonuclear leukocytes (PMNLs), the interaction between activated PMNLs and endothelial cells (ECs), and the effects of pentoxifylline (PTX). The ECs were obtained from a commercial source as human umbilical cord vein endothelial cells (HUVECs) or were obtained from pig or rat brains. They were cultured on a coverglass with DMEM for about 1 week. The human PMNLs were obtained from the authors' venous blood. The control appearance of the PMNLs resembled an elastic ball covered with fine villi. The PMNL was activated spontaneously and became flattened on the glass surface within 10 min in the observation chamber. The activation of the PMNLs was estimated arbitrarily from the polymorphous changes in cell shape, agitation of the intracellular granules, and apparent increase in adhesiveness. Preadministered PTX prevented such PMNL activation, and the PMNLs remained round for more than 15 min. PMNL activation was accelerated by chemoattractants (PAF, fMLP, and PMA). In one case, a PMNL that had been activated by PMA tended to recover its round shape with PTX, but finally ended by swelling and bursting. When PMNLs were introduced into the EC-containing chamber, they became entrapped by the ECs and activated, with degranulation followed by release of a smoke-like material. After about 3 h, the EC with an attached PMNL shrank and fell into a state of coagulation necrosis. When PTX was introduced at the time of adhesion of the flattened PMNL, the PMNL appeared to be deactivated, becoming smaller and assuming its previous round shape, and detached from the EC. PTX prevented the spontaneous activation of PMNLs, and of deactivated PMNLs even after their adherence to the endothelium.

Animals↗

PubMed1994

CT changes associated with normal aging of the human brain.

CT was used to measure changes in cerebral gray and white matter tissue densities associated with normal aging, using a cross-sectional design, in order to provide normative data for comparisons with abnormal aging such as dementias of Alzheimer's and vascular types. Cerebral compartmental densities were measured using plain CT, and their perfusion values were recorded during stable xenon inhalation (CT-CBF), among 81 neurologically and cognitively normal volunteers of different ages. Results led to the conclusion that cortical gray matter tissue densities progressively decline (polio-araiosis) after age 60. Cortical polio-araiosis is coupled with regional hypoperfusion but not with cortical atrophy. It is speculated that the cortical hypodensity identified by CT imaging parallels declines in cortical synaptic density, as reported from autopsy studies using anti-synaptophysin staining of cerebral cortex obtained from normal people above and below age 60. The coupling of cortical hypoperfusion with polio-araiosis is believed to reflect age-related reductions of cortical metabolic demands as reported by PET. During normal aging leuko-araiosis correlates directly with cortical atrophy, suggesting that anterograde axonal degeneration resulting from cortical neuronal dearborization play a role in its causation.

Adult↗

PubMed1994

Prospective studies of cerebral perfusion and cognitive testing among elderly normal volunteers and patients with ischemic vascular dementia and Alzheimer's disease.

To compare longitudinal changes of cerebral perfusion (CBF) and cognitive status in two common forms of dementia in the elderly, 42 patients with ischemic vascular dementia (IVD), 44 patients with dementia of the Alzheimer type (DAT), and 120 elderly normal volunteers were evaluated prospectively over a mean interval of 3.35 years. Subjects were at least age sixty, (mean age 71.1). Mean bihemispheric cerebral blood flow and cognitive test scores of control subjects were significantly higher than those of both demented groups at entry and remained so. After adjustment for initial CBF, course over time was similar for all groups. Group variability was similar for CBF but not for cognition. Both IVD and DAT patients were more variable than controls but similar to each other. Throughout, DAT patients showed greater cognitive impairments than IVD patients. Cognitive impairments stabilized among IVD patients treated by control of risk factors, antiplatelet or anticoagulant therapy but declined progressively among DAT patients.

Age Factors↗

PubMed1993

Cognitive recovery correlates with white-matter restitution after head injury.

Longitudinal measurements of local cerebral perfusion (LCBF) and local partition coefficients (L lambda) using xenon-enhanced computed tomography were examined in six patients who had suffered from head injury at a mean age of 30 +/- 9.3 years. They were selected from a larger group with head injury because all were observed longitudinally to make excellent cognitive recovery some years after acute cerebral trauma. Results were compared with similar longitudinal measurements made in six age-matched neurologically normal volunteers. In the index group, cognitive test scores were reduced at the time of the first LCBP measurement but significantly improved to normal at the time of the second. The mean interval between measurements was 2.7 +/- 0.7 years. At the time of the first measurement, all six patients exhibited abnormal volumes of white matter with reduced Hounsfield numbers and LCBF and L lambda values. Abnormalities in volume of white matter and LCBF and L lambda values improved to normal at the time of the second measurement. Perfusion values for frontal cortex, putamen, and thalamus were still slightly reduced but also improved toward normal between measurements. Cognitive recovery correlated best with restoration of white matter integrity, suggesting that following head injury, cognitive impairments may be associated with temporary disconnections of corticothalamic projection systems.

Adult↗

PubMed1993

Correlations of leuko-araiosis with cerebral atrophy and perfusion in elderly normal subjects and demented patients.

CT images of leuko-araiosis in brain slices were quantified according to volumes of reduced Hounsfield units in frontal periventricular white matter in groups of elderly patients with multi-infarct dementia (MID, n = 23) and dementia of the Alzheimer type (DAT, n = 16). Volumes of leuko-araiosis, estimates of atrophic cerebral tissue, and local cerebral perfusion utilising inhalation of xenon gas as the indicator were correlated on the same CT slices. Ratios of frontal leuko-araiosis to total brain tissue volume were similar for patients with MID and DAT (mean 5.7 (SD 2.1)% v 6.5 (3.2%)), and both were significantly greater than ratios in elderly normal volunteers (3.1(1.3)%, 0 < 0.001). Cerebral atrophy (measured as the ratio of volumes of cerebrospinal fluid to total brain area) for DAT patients was 17.0 (6.7)%, which was greater than for MID patients (12.5 (5.4)%; p < 0.05) and both types of patients showed more cerebral atrophy than did age matched, elderly normal subjects. Cerebral perfusion was decreased in all regions measured in patients with MID and DAT compared with elderly normal subjects. Multi variate regression analyses correlated frontal leuko-araiosis with reductions of local cerebral blood flow in subcortical grey matter (p < 0.025) in patients with vascular dementia but not in those with DAT. These quantitative measures implicate decreased perfusion due to atherosclerosis in territories supplied by the deep penetrating cerebral arteries in the pathogenesis of leuko-araiosis in patients with vascular dementia, but suggest a different pathogenesis for leuko-araiosis in Alzheimer's disease.

Aged↗

PubMed1993

Cerebral circulation in the elderly.

A great deal of knowledge has been accumulated in recent years, concerning the aging human brain in health and disease, with the advent of newer methods of measuring cerebral blood flow (CBF) and metabolism. It is well documented that even in normal aging, the functional metabolism of the brain and its blood supply inevitably decline. This accounts for the widespread clinical observations that the young tolerate disorders of the brain better than do the elderly. It also accounts for difficulties in correctly diagnosing and treating cognitive disorders among the elderly. Neuronal and vascular reserves become progressively depleted during normal aging, so that one or more different disease processes may contribute to cognitive declines. Computed tomography (CT) densitometry, coupled with xenon-enhanced CT CBF measurements, provide a noninvasive method for separating the changes within cerebral cortex, subcortex, and white matter that occur in normal aging from those due to pathological abnormalities.

Aged↗

PubMed1992

White matter lesions in the elderly.

The advent of neuroimaging has brought medical attention to the frequency of unsuspected white matter lesions in the brains of elderly people. In 1987 Hachinski suggested the term "leuko-araiosis" to identify such white matter abnormalities detected by computed tomography and magnetic resonance imaging to emphasize that their etiology and clinical relevance require clarification. Since then, leuko-araiosis has been recognized among approximately ten percent of apparently normal, elderly people over age sixty-five. The severity and frequency of leuko-araiosis increases with advancing age, risk factors for stroke, history of strokes particularly of the lacunar type and dementia of both the vascular and Alzheimer type. Current concepts concerning the pathogenesis and neurological concomitants of leuko-araiosis are reviewed. The etiology of leuko-araiosis may be heterogeneous but is most likely ischemic in nature. However, as white matter lesions progress among the elderly they are likely to become associated with cognitive impairments and motor dyspraxias presumably resulting from cortico-subcortical disconnections, particularly involving the frontal cortex and basal ganglia and may themselves be considered a radiological "risk factor" or precursor for dementia.

Aged↗

PubMed1992

Leuko-araiosis and cerebral hypoperfusion compared in elderly normals and Alzheimer's dementia.

OBJECTIVE: To elucidate the pathogenesis of leuko-araiosis in patients with Alzheimer's disease by utilizing CT densitometry of the brain and measurements of local perfusion in order to quantify the extent of leuko-araiosis and local hypoperfusion compared with similar measurements made among age-matched normal volunteers. DESIGN: Cross-sectional case-control study. SETTING: Out-patient visits to a specialized laboratory located in a large hospital facility. PATIENTS: Eighteen elderly patients with probable dementia of Alzheimer type (DAT, aged 71.8 +/- 5.1 years) and 17 neurologically and cognitively normal, age-matched volunteers (aged 68.2 +/- 9.6 years) were admitted to the study according to established criteria. INTERVENTION: None MAIN OUTCOME MEASURES: Cerebral blood flow (mL/100 g brain/min) estimated by the xenon inhalation CT-CBF method correlated with volume percentage ratio (%) measured by CT densitometry for leuko-araiosis, compared to normal white and gray matter. RESULTS: Perfusion values for frontal and occipital white matter as well as frontal, parietal, temporal, and occipital cortex were all decreased in DAT patients. Ratios for leuko-araiosis to total brain tissue volumes were greater among patients with DAT compared with age-matched normal volunteers. White matter perfusion in zones of leuko-araiosis was decreased to a similar degree in both DAT and elderly normal volunteers. CONCLUSIONS: Perfusion is reduced to the same degree in regions of leuko-araiosis in elderly normals as in DAT patients, but the extent of leuko-araiosis is greater among DAT patients and presumably contributes to cognitive impairments.

Aged↗

PubMed1992

Animal species differences in erythrocyte aggregability.

Species differences in erythrocyte aggregability were investigated employing our whole blood erythrocyte aggregometer. Blood was sampled from seven species, including humans and anesthetized (30 mg/kg pentobarbital) animals. The erythrocyte aggregation rates were the following (in s-1): cats, 0.213 +/- 0.027 (means +/- SD); dogs, 0.164 +/- 0.027; men, 0.112 +/- 0.025; rats, 0.111 +/- 0.005; domestic rabbits, 0.049 +/- 0.021; and mongolian gerbils, 0.034 +/- 0.015. Domestic fowls did not exhibit erythrocyte aggregograms like those seen in the other species. Statistical analysis revealed significant differences among the erythrocyte aggregation rates of the different species (multiple-comparisons with an overall significance level of 0.05) except between men and rats and between rabbits and gerbils. No single factor which is known to accelerate the erythrocyte aggregation rate (hematocrit, fibrinogen, etc.) was correlated with the erythrocyte aggregation rate except the globulin concentration in the blood. The failure to detect erythrocyte aggregation in domestic fowls was probably attributable to their erythrocyte shape. These results suggest that each species has its own proper tendency for erythrocyte aggregation. This factor must be taken into consideration when the blood circulation is discussed among different animal species.

Animals↗

PubMed1992

Patterns of cerebral hypoperfusion compared among demented and nondemented patients with stroke.

BACKGROUND AND PURPOSES: No reports are available that compare local cerebral perfusion among groups of patients suffering from multiple cerebral infarctions with and without cognitive impairments. The present study was designed to correlate changes in regional cerebral perfusion that may lead to dementia among patients with multiple cerebral infarctions by comparing measurements of local cerebral blood flow. METHODS: Local perfusion was measured using xenon-contrasted computed tomographic scanning among two groups of patients who had suffered from multiple cerebral infarctions: Group D (n = 12) were demented and had severe cognitive impairments, and group I (n = 11) were cognitively intact. Results were compared with similar measurements among neurologically and cognitively normal, age-matched volunteers (group N, n = 16). RESULTS: Mean local perfusion values were reduced among both groups with cerebral infarctions but to a more marked degree in group D (p less than 0.05). Perfusion of cerebral white matter was diffusely and severely reduced in group D (p less than 0.05) but was mildly reduced only in frontal and capsular white matter in group I (p less than 0.05). Perfusion of cerebral cortex was reduced in frontal (p less than 0.01) and temporal (p less than 0.01) regions among both groups but to a significantly greater degree in group D subjects (frontal, p less than 0.05; temporal, p less than 0.01), who also showed hypoperfusion of the occipital cortex (p less than 0.05), apparently because of underlying leukoaraiosis and cortical disconnections. Perfusion of the basal ganglia was reduced to the same degree among both groups of stroke patients (p less than 0.01). CONCLUSIONS: Leukoaraiosis with white matter hypoperfusion appears to be an important determinant for cognitive impairments among patients with multiple cerebral infarctions.

Aged↗

PubMed1991

Cerebral hypoperfusion correlates with mild and parenchymal loss with severe multi-infarct dementia.

Relative contributions of two potential pathogenetic factors for cognitive impairments among patients with multi-infarct dementia (MID) are reported. Cognitive test scores were correlated with measures of cerebral hypoperfusion and loss of brain parenchyma. Local cerebral blood flow values were determined utilizing stable xenon contrasted computed tomography and volumes for brain parenchyma were estimated from ratios of volumes of infarcted brain plus cerebrospinal fluid/total intracranial volume measured on the same CT slices among two groups of patients, one with mild and the other with severe MID. A total of 26 demented patients with multiple cerebral infarcts were divided into 2 index groups, one with mild and the other with severe MID (mild MID, CCSE greater than or equal to 15, n = 16; severe MID, CCSE less than 15, n = 10). Results were compared with similar measures among age-matched neurologically normal volunteers (n = 14). Ratios for volumes of lost brain parenchyma were significantly higher among severe MID patients than among age-matched normal volunteers, whereas estimates of brain loss among patients with mild MID did not differ from elderly normal volunteers. In patients with mild MID, LCBF values for cortical gray matter were decreased compared with age-matched normal volunteers. Results suggest that chronic cerebral hypoperfusion is an important determinant for mild dementia among patients in the early stages of MID, but volumes of lost cerebral parenchyma due to cerebral infarctions is an important determinant for advanced stages of MID.

Aged↗

PubMed1991

Cognitive recovery correlates with long-term increases of cerebral perfusion after head injury.

Prospective measurements of cerebral blood flow (CBF) and Cognitive Capacity Screening Examination (CCSE) were obtained following head injury among 42 patients for a mean total follow-up interval of 10 years. Clinical data obtained at the time of injury and detailed neurological examinations at each follow-up visit were correlated with serial CBF and CCSE scores. Comparisons of the group of patients who cognitively improved (n = 32) were made with the group that did not (n = 10). Of the total group, 76% showed cognitive improvements for as long as 10 years after injury, with CBF increases toward normal. Predictors for long-term cognitive improvements include: higher initial Glasgow Coma Scales, earlier recovery from coma, absence of signs of brain stem injury, and improvements of cerebral perfusion and autoregulation. Failure to improve correlated with low initial Glasgow Coma Scales, signs of brain stem injury, and persistent impairments of cerebral perfusion.

Adolescent↗

PubMed1991

Role of thalamus and white matter in cognitive outcome after head injury.

Local CBF (LCBF) and local partition coefficients (L lambda) were measured by xenon-enhanced computed tomography among 15 patients with remote cerebral trauma resulting from severe head injury. Results were compared with similar measures among age-matched normal volunteers (N = 20). The patients were divided into two groups according to different outcomes based on serial cognitive testing: Group I (N = 10) improved but Group D (N = 5) deteriorated throughout a mean interval of 10 years of follow-up. Initial LCBF measurements were performed at mean intervals of 6.8 years after injury. Cortical LCBF values were decreased in frontal (p less than 0.01) and temporal (p less than 0.05) regions among both groups, but only in Group D were flow values decreased in putamen and thalamus (p less than 0.05). L lambda values were reduced in frontotemporal cortex among both groups but in the thalamus only among Group D (p less than 0.05). Mean white matter flow values were normal in Group I but were reduced in Group D (p less than 0.05). Mean partition coefficients for white matter were reduced in both groups (p less than 0.01) but were lower in Group D (p less than 0.05). Reduced perfusion of frontotemporal gray matter is consonant with neuropathological reports following severe brain trauma of neuronal atrophy, gliosis, and infarction affecting these regions. Group comparisons between patients who cognitively improved versus those that deteriorated demonstrate an association between reductions of CBF in putamen, thalamus and subcortical white matter and impaired cognition after severe head injury.

Adolescent↗

PubMed1991

Cerebral white matter perfusion in dementia of Alzheimer type.

Local cerebral blood flow was measured in 19 patients with probable dementia of Alzheimer type (DAT) by using xenon-enhanced computerized tomography (CT) and CT densitometry to accurately differentiate white from gray matter. Patients met standard diagnostic criteria for probable DAT and results were compared with similar measures in 26 age-matched, neurologically and cognitively normal volunteers. Perfusions of frontal and occipital white matter as well as frontal, parietal, temporal, and occipital cortex were reduced in DAT compared with age-matched normals. White matter perfusion differences were not observed among DAT patients with and without risk factors for stroke. Reduced perfusion of frontal white matter correlated significantly with reduced perfusion of thalamus and putamen in patients with DAT. Results confirm the frequent association of white matter abnormalities in patients with DAT that are possibly caused by amyloid angiopathy and may contribute to cognitive impairments.

Aged↗

PubMed1991

Cerebral hyperemia during spontaneous cluster headaches with excessive cerebral vasoconstriction to hyperoxia.

Values for local cerebral blood flow (LCBF) were measured in three dimensions utilizing xenon enhanced computerized tomography among patients during spontaneously occurring cluster headaches, during headache-free intervals and immediately after terminating attacks by inhalation of 100% oxygen. Results were compared with values measured among age-matched normal volunteers. LCBF values measured in five cluster patients while headache-free did not differ from similar measures among age-matched normal volunteers. In three patients during attacks of spontaneously occurring cluster headache, LCBF values for temporal cortex, basal ganglia and subcortical white matter were increased. Immediately after terminating attacks of cluster by 100% oxygen inhalation for five minutes, LCBF values for temporal cortex and basal ganglia became significantly decreased below normal values in five patients with spontaneously occurring cluster headache. Prompt relief of head pain by inhalation of 100% oxygen is associated with abolition of the hyperperfusion of both cortical and subcortical brain structures that occurs during spontaneously occurring cluster headaches and is followed by excessive cerebrovascular constriction. It remains to be determined whether the cerebral hyperemia occurring during cluster headaches is causally related to the head pain or is secondary to the pain itself. Rapid termination of head pain by hyperoxia associated with excessive cerebral vasoconstriction suggests that this vascular phenomenon is unique to cluster headache and offers clues to its pathogenesis.

Administration, Inhalation↗

PubMed1991

Leukoaraiosis correlates with cerebral hypoperfusion in vascular dementia.

Leukoaraiosis quantified by computerized densitometric measurements of reduced Hounsfield numbers was correlated with local cerebral blood flow on the same computed tomographic images of 35 patients with multi-infarct dementia and 16 age-matched elderly normal volunteers. The ratio for area of frontal leukoaraiosis to total area of parenchyma among the patients was significantly greater than that among the normal volunteers (5.8 +/- 2.3% compared with 3.1 +/- 1.3%, p less than 0.001). Severity of leukoaraiosis around the frontal horns of the lateral ventricles correlated significantly with severity of leukoaraiosis of the centrum semiovale adjacent to the bodies of the lateral ventricles. Cerebral blood flow values for all representative cerebral regions except the parietal white matter were reduced among the patients compared with the normal volunteers. Multivariate regression analysis revealed that reduced cerebral perfusion in the putamen and thalamus correlated significantly with the severity of leukoaraiosis. Cerebral hypoperfusion in territories supplied by deep penetrating arteries may contribute to the pathogenesis of leukoaraiosis.

Adult↗