PubMed Health⌕ Search

Biomedical subjects

Hiroaki Naritomi

Publications and source records attributed to Hiroaki Naritomi.

At least 19 recordsLinked to original sources
PubMed2006

Microembolic signals within 24 hours of stroke onset and diffusion-weighted MRI abnormalities.

BACKGROUND: The clinical relevance of the microembolic signals (MES) detected by transcranial Doppler sonography (TCD) in acute stroke remains unclear. In a prospective study the authors analyzed the relationship between MES and the findings on diffusion-weighted magnetic resonance imaging (DWI) in acute stroke patients. METHODS: We performed TCD for a period of 30 min to detect MES in patients within 24 h of stroke onset, and DWI was done within the initial 7 days. MES were assessed from Doppler waves obtained from the middle cerebral artery contralateral to the side of the neurological deficits. The acute ischemic lesions observed on DWI were classified by their diameter (small, medium or large) and by their site (cortical, superficial perforator territory, internal borderzone or deep perforator territory). RESULTS: We obtained Doppler waves from 39 vessels in 37 patients; 2 patients had bilateral deficits. MES were detected in 12 vessels (MES-positive group) and not detected in 27 vessels (MES-negative group). No significant differences in clinical features were observed between the 2 groups. The number of small lesions was significantly higher in the MES-positive group than in the MES-negative group (p = 0.02). The numbers of cortical and superficial perforator infarcts were significantly higher in the MES-positive group than in the MES-negative group (p = 0.002 and 0.02, respectively). CONCLUSION: In acute ischemic stroke, MES detected by TCD in the acute phase may produce small cortical and subcortical lesions found on DWI.

Acute Disease↗
PubMed2006

Genotypes of vitamin K epoxide reductase, gamma-glutamyl carboxylase, and cytochrome P450 2C9 as determinants of daily warfarin dose in Japanese patients.

The dose required for the anticoagulant effect of warfarin exhibits large inter-individual variations. This study sought to determine the contribution of four genes, vitamin K epoxide reductase (VKORC1), gamma-glutamyl carboxylase (GGCX), calumenin (CALU), and cytochrome P450 2C9 (CYP2C9) to the warfarin maintenance dose required in Japanese patients following ischemic stroke. We recruited 93 patients on stable anticoagulation with a target International Normalized Ratio (INR) of 1.6-2.6. We genotyped eleven representative single nucleotide polymorphisms (SNPs) in the three genes involved in vitamin K cycle and the 42613A>C SNP in CYP2C9, known as CYP2C93, and then examined an association of these genotypes with warfarin maintenance doses (mean+/-SD=2.96+/-1.06 mg/day). We found an association of effective warfarin dose with the -1639G>A (p=0.004) and 3730G>A genotypes (p=0.006) in VKORC1, the 8016G>A genotype in GGCX (p=0.022), and the 42613A>C genotype in CYP2C9 (p=0.015). The model using the multiple regression analysis including age, sex, weight, and three genetic polymorphisms accounted for 33.3% of total variations in warfarin dose. The contribution to inter-individual variation in warfarin dose was 5.9% for VKORC1 -1639G>A, 5.2% for CYP2C9 42613A>C, and 4.6% for GGCX 8016G>A. In addition to polymorphisms in VKORC1 and CYP2C9, we identified GGCX 8016G>A, resulting in the missense mutation R325Q, as a genetic determinant of warfarin maintenance dose in Japanese patients.

Aged↗
PubMed2006

Polyarteritis nodosa in association with subarachnoid hemorrhage.

We report a 65-year-old man with classic polyarteritis nodosa (PAN) who developed subarachnoid hemorrhage. Polyarteritis nodosa was strongly suspected, however, the biopsy specimens of kidney and sural nerve showed no findings of vasculitis and the serum titer of antimyeloperoxidase-antineutrophil cytoplasmic autoantibody (MPO-ANCA) was negative. Cranial magnetic resonance angiography showed no findings of aneurysms. He developed subarachnoid hemorrhage (SAH) during the course and died. Autopsy confirmed fibrinoid necrosis in the medium-sized artery of multiple organs. To our knowledge, this is the first report of a case of classic PAN accompanied by SAH in which MPO-ANCA proved negative.

Aged↗
PubMed2006

Early CT findings in unknown-onset and wake-up strokes.

BACKGROUND: Approximately one quarter of the acute ischemic stroke patients notice the event at awakening. Such patients with stroke at awakening are usually excluded from thrombolysis, since the time of stroke onset cannot be definitely identified. We compared the hyperacute CT findings of awakening stroke patients with those of stroke patients with known onset to assess whether the time of stroke onset is shortly before awakening. METHODS: Subjects were cardioembolic stroke patients who were consecutively admitted to our department within 3 h after the recognition of stroke during the period between January 2000 and March 2003. The patients were classified into three groups: group A with stroke of known onset, group B with stroke at awakening, and group C with stroke of unknown onset due to lack of a witness. The clinical and CT findings in each group were compared. RESULTS: A total of 81 patients fulfilled the study criteria. There were 46 patients in group A, 17 patients in group B, and 18 patients in group C. There was no significant difference in CT findings between groups A and B. In group C, however, definite hypodense areas were more commonly found than in group A (56 vs. 0%; p<0.001) or in group B (56 vs. 11%; p=0.012). CONCLUSION: Based on our CT findings, stroke at awakening seems to be developing shortly before in a large subset of patients, making them potential candidates for acute stroke therapies.

Adult↗
PubMed2006

Primary intracerebral hemorrhage during asleep period.

BACKGROUND: The onset of intracerebral hemorrhage (ICH) has a circadian variation, with a lower risk during the asleep period. It is unclear, however, whether ICH during the asleep period differs from that during the awake period in pathophysiologic nature. The purpose of this study is to elucidate the incidences and clinical features of ICH during the asleep period. METHODS: We studied 129 consecutive patients with primary ICH and classified them into two groups according to the circumstance of their stroke onset, either during the awake period (awake ICH group) or the asleep period (asleep ICH group). Demographic and clinical characteristics were then compared between the two groups. RESULTS: Of the patients, 19 (14.7%) had ICH during the asleep period. The mortality rate at 1 month after the stroke was significantly higher in the asleep ICH group than in the awake ICH group (21.1% v 4.9%, P = .0325). The hemorrhage volume in the asleep ICH group was also significantly larger than that in the awake ICH group (mean volume, 32.6 mL v 16.7 mL, P = .0122). CONCLUSIONS: Our findings indicate that ICH during the asleep period may be more detrimental compared with ICH during the awake period, causing larger hematoma and higher mortality rates.

Aged↗
PubMed2006

Polymorphisms in vitamin K-dependent gamma-carboxylation-related genes influence interindividual variability in plasma protein C and protein S activities in the general population.

gamma-Glutamyl carboxylation, a reaction essential for the activity of vitamin K-dependent proteins, requires the concerted actions of gamma-glutamyl carboxylase (GGCX), vitamin K 2, 3-epoxide reductase complex 1 (VKORC1), and the chaperone calumenin (CALU). We evaluated the contribution of genetic polymorphisms in VKORC1, GGCX, and CALU to interindividual variation in the activities of plasma protein C and protein S. We sequenced these 3 genes in 96 Japanese individuals and geno-typed 9 representative single-nucleotide polymorphisms in 3655 Japanese individuals representative of the general population. The mean activity of protein C in women bearing the GG genotype of GGCX 8016G>A (130.8% +/- 1.5%, n = 156) was significantly greater (P = .002) than that of individuals with either the AG (126.8% +/- 0.7%, n = 728) or the AA (125.4% +/- 0.6%, n = 881) genotype, after adjusting for confounding factors. The GGCX 8016G>A change leads to the substitution of Gin for Arg at amino acid residue 325 (Arg 325 Gln). This effect was comparable to that of a previously defined polymorphism in the protein C promoter. Mean protein S activity was influenced by the VKORC1 3730G>A and CALU 20943T>A genotypes, after adjusting for confounding factors. Thus, polymorphisms in genes involved in the vitamin K-dependent gamma-carboxylation reaction influence interindividual variation in the activities of protein C and protein S in the general population.

Aged↗
PubMed2005

Moderate atheroma of the aortic arch and the risk of stroke.

BACKGROUND AND PURPOSE: Severe atheroma >or=4 or 5 mm of the aortic arch is a risk factor for stroke. We investigated the most predictive characteristics of arch atheroma, including maximal plaque thickness, for subsequent cardiovascular events, and also examined whether moderate atheroma<4 mm is a risk of cerebral emboli. METHODS: The maximal plaque thickness (MPT) and plaque morphologies of the aortic arch were evaluated by transesophageal echocardiography in 236 patients with ischemic stroke. We assessed the relationship between the incidence of cardiovascular events, recurrent stroke or myocardial infarction, and the characteristics of the atheroma. We also investigated the thickness of atheroma in patients with known causes of stroke (n=148) and in patients with undetermined causes (n=19). RESULTS: Cardiovascular events occurred in 47 patients in the follow-up period with a mean of 3.5 years. MPT was a significant risk factor of the cardiovascular events, although plaque morphologies were not. For the receiver operator characteristics curve analysis, the suitable cutoff point of MPT associated with the cardiovascular events was 3.5 mm. Patients with MPT >or=3.5 mm had a higher risk of cardiovascular events than did those with MPT<3.5 mm. In addition, aortic atheroma with MPT >or=3.5 mm was more frequently observed in patients with undetermined causes of stroke than those with known causes at 68 vs. 39% (p=0.024). CONCLUSIONS: MPT >or=3.5 mm is the best predictor of subsequent cardiovascular events and a possible cause of embolic stroke.

Aged↗
PubMed2005

Diagnosis of middle cerebral artery occlusive lesions with contrast-enhanced transcranial color-coded real-time sonography in acute stroke.

It is useful to evaluate the occlusive lesions of middle cerebral artery (MCA) occlusion with transcranial color-coded real-time sonography (TCCS). However, TCCS criteria for locating the site of the MCA occlusion has, as yet, remained unclear. The aim of the present study was to establish TCCS criteria for MCA occlusive lesions. We prospectively performed contrast-enhanced TCCS (CE-TCCS) in 75 consecutive acute stroke patients within 24 h of digital subtraction angiography. Patients were divided into four groups: occlusion of the MCA stem (MO group, n=12); occlusion of the MCA branch (MBO group, n=10); stenosis of the MCA stem (MS group, n=9); and no occlusive or stenotic lesions (control group, n=44). The following parameters were measured: peak systolic velocity (PSV) and end diastolic velocity (EDV) of bilateral MCA stems, and ED-ratio (the side-to-side ratio of the EDV). We establish the CE-TCCS criteria for MCA occlusive lesions using the sensitivity-specificity curve analysis. A PSV of 170 cm/s distinguished MCA stenosis from other groups (positive and negative predictive values and the accuracies were 100%, 99.0% and 99.1%, respectively). An EDV of 26 cm/s differentiated MO or MBO from the other groups (positive and negative predictive values and the accuracies were 84.6%, 100% and 96.5%, respectively). An ED-ratio of 2.5 discriminated MO from the MBO group (positive and negative predictive values and the accuracies were 88.9%, 85.7% and 87.5%, respectively). Measurement of MCA stem flow velocity with CE-TCCS can identify MCA stem stenosis and occlusion, as well as MCA branch occlusion.

Aged↗
PubMed2005

Optimal dose of prothrombin complex concentrate for acute reversal of oral anticoagulation.

We investigated optimal dose of prothrombin complex concentrate (PCC) for acute reversal of oral anticoagulation in patients with major hemorrhagic complications or who required invasive procedures. We also checked how rapidly international normalized ratio (INR) was reversed after PCC administration. INR was measured before and 10-60 min after administration of PCC with or without vitamin K in 42 patients (men 28, women 14, median age of 70 years old) who had received warfarin but required rapid reversal of INR because of a hemorrhagic complication or medical procedure. The amount of PCC administered was 200 IU in six patients, 500 IU in 30, 1000 IU in 3, and 1500 IU in the other 3. Additional administration of PCC was performed when the correction of INR was inadequate. In 10 of the 42 cases, INR was measured serially, before, 10 and 60 min and 12-24 h after the administration of PCC and vitamin K. In the six patients who received PCC of 200 IU, INR values of 3.34 median (range 2.06 to 5.08) decreased to 1.85 (range 1.23 to 2.43) significantly (Wilcoxon's rank sum test, p=0.028), but in three patients (50%), INR values were still above 2.0 after the administration. In 30 patients treated with PCC of 500 IU, values decreased from 2.49 median (range 1.54 to 10.00) to 1.19 (range 0.87 to 1.55) significantly (p<0.0001). The corrected INR values were below 1.5 in 25 of 26 patients (96%) who had initial INR values from 2.0 to 4.9. In four patients with initial INR of 5.0 or more, the reversed INR was below 1.5 in one (25%), between 1.5 and 2.0 in two (50%), and above 2.0 in one (25%) who had additional administration of 500 IU PCC lowering INR from 2.01 to 1.48. Values of INR in the six patients receiving 1000 IU or 1500 IU, INR decreased from 2.33 median (range 1.96 to 4.00) to 0.96 (range 0.87 to 1.24, p=0.028). In the 10 patients with serial measurement, INR changed from 2.67 median (range 2.05 to 10.00) to 1.17 (range 0.99 to 1.60) 10 min after the administration. The INR values remained stable 60 min and 12-24 h after the PCC administration. The 500 IU of PCC is likely to be optimal dose of PCC for emergent reversal of INR in patients requiring rapid correction of INR below 5.0, but to be inadequate dose in patients with INR of 5.0 or more. PCC administration with vitamin K may finish reversing INR rapidly within 10 min and keep the reversed INR values for 12-24 h.

Administration, Oral↗
PubMed2005

"A girdle-like tightening sensation" misapprehended as abdominal splanchnopathy in a sarcoidosis patient.

We describe a 53-year-old man with the isolated manifestation of girdle-like tightening sensation of the trunk due to polyradiculopathy at the beginning of sarcoidosis which was first misapprehended as abdominal splanchnopathy. Late development of other neurological and systemic symptoms led to the final diagnosis of sarcoidosis. Segmental dysesthesia at the trunk in neurosarcoidosis is unique and may mimic a splanchnic pain. Such a dysesthesia may be solely manifested at the beginning of sarcoidosis and may continue for days without other symptoms. When patients complain of a girdle-like tightening with unknown etiology, sarcoidosis should be suspected as the possible cause.

Abdomen↗
PubMed2005

Mechanisms of bihemispheric brain infarctions in the anterior circulation on diffusion-weighted images.

BACKGROUND AND PURPOSE: Multiple acute brain infarctions in both cerebral hemispheres usually suggest an embolic mechanism, particularly one of aortic or cardiac origin. The purpose of this study was to clarify the etiologic mechanisms and topographic features of bihemispheric infarctions depicted on diffusion-weighted imaging (DWI). METHODS: Among 411 consecutive patients with ischemic stroke who underwent MR imaging in the acute phase, DWI showed bilateral infarctions in 19 (4.6%). In these patients, we analyzed the presence of carotid, aortic or cardiac embolic sources by using ultrasonography, cerebral angiography, and/or transesophageal echocardiography and evaluated the size and topographic distribution of the lesions. We assessed intracranial cross-flow through the anterior communicating artery, mainly on the basis of the anatomic information obtained from angiography or MR angiography. RESULTS: Bilateral lesions were derived from cardiac and/or aortic embolic sources in 16 (84%) of 19 patients and appeared to originate from unilateral carotid diseases in three (16%). In nine (82%) of 11 patients with cardiac embolic sources, at least one large territorial or subcortical lesion was found in either hemisphere, whereas in all eight patients without a cardiac embolic source, the lesions were small and disseminated bilaterally. CONCLUSION: Unilateral carotid lesions can cause bihemispheric infarctions through cross-flow in the anterior communicating artery. On DWI, small bihemispheric, disseminated lesions strongly suggest an artery-to-artery embolism. In such cases, aortic and carotid lesions should be assessed as potential embolic sources.

Aged↗
PubMed2005

[Incongruous homonymous quadrantanopia due to suprasellar calcificated lesions].

A 53 year-old woman with a history of tuberculous meningitis at 3 years of age incidentally found a right incongruous homonymous quadrantanopia in ophthalmologic check-up. On magnetic resonance imaging and helical computed tomography, the left optic tract was obscured by suprasellar calcified lesions. The left internal carotid artery was diffusely narrowed and occluded at its terminal portion as demonstrated by cerebral angiography. The calcificated lesions were diagnosed to derive from old tuberculous meningitis on the basis of her history, their location and the association of vascular occlusive changes. Incongruous homonymous hemianopsia due to optic tract damage is usually caused by tumor or aneurysm. Its occurrence by calcified inflammatory lesions has never been reported previously. The present case is considered of value in this respect.

Calcinosis↗
PubMed2004

Circulating CD34-positive cells provide an index of cerebrovascular function.

BACKGROUND: Increasing evidence points to a role for circulating endothelial progenitor cells, including populations of CD34- and CD133-positive cells present in peripheral blood, in maintenance of the vasculature and neovascularization. Immature populations, including CD34-positive cells, have been shown to contribute to vascular homeostasis, not only as a pool of endothelial progenitor cells but also as a source of growth/angiogenesis factors at ischemic loci. We hypothesized that diminished numbers of circulating immature cells might impair such physiological and reparative processes, potentially contributing to cerebrovascular dysfunction. METHODS AND RESULTS: The level of circulating immature cells, CD34-, CD133-, CD117-, and CD135-positive cells, in patients with a history of atherothrombotic cerebral ischemic events was analyzed to assess possible correlations with the degree of carotid atherosclerosis and number of cerebral infarctions. There was a strong inverse correlation between numbers of circulating CD34- and CD133-positive cells and cerebral infarction. In contrast, there was no correlation between the degree of atherosclerosis and populations of circulating immature cells. Analysis of patients with cerebral artery occlusion revealed a significant positive correlation between circulating CD34- and CD133-positive cells and regional blood flow in areas of chronic hypoperfusion. CONCLUSIONS: These results suggest a possible contribution of circulating CD34- and CD133-positive cells in maintenance of the cerebral circulation in settings of ischemic stress. Our data demonstrate the utility of a simple and precise method to quantify circulating CD34-positive cells, the latter providing a marker of cerebrovascular function.

AC133 Antigen↗
PubMed2004

Vertebral artery occlusion in duplex color-coded ultrasonography.

BACKGROUND AND PURPOSE: To establish the diagnostic criteria for the site of occlusion in the vertebral arteries (VAs) using duplex color-coded ultrasonography. METHODS: In 128 consecutive patients who underwent conventional cerebral angiography, we prospectively measured the diameter, mean flow velocity (MV), peak systolic flow velocity, and end-diastolic flow velocity of both VAs. The diameter-ratio (diameter of contralateral VA divided by that of target VA) and MV-ratio (MV of contralateral VA divided by that of target VA) were determined. Based on the angiographic findings, we classified the VAs into 4 types (5 groups) as follows: (1) the origin of VA occlusion (Origin group: n=9); (2) VA occlusion before branching into the posterior inferior cerebellar artery (PICA) (Before group: n=10); (3A) symptomatic VA occlusion after branching into the PICA (After group: n=12); (3B) asymptomatic or hypoplastic occlusive VA after branching into the PICA (PICA end group: n=15); and (4) no significant occlusive lesions in the VA (Control group: n=194). RESULTS: No flow signals in the VAs apparently indicated the Origin group. Preserved peak systolic flow velocity but end-diastolic flow velocity of zero cm/s indicated the Before group. MV <18 cm/s and MV-ratio > or =1.4 indicated the PICA end group or After group. Furthermore, these groups could be distinguished as follows: a diameter-ratio <1.4 indicated the After group. A diameter-ratio > or =1.4 indicated the PICA end group. Either MV > or =18 cm/s or MV <18 cm/s in combination with MV-ratio <1.4 indicated the Control group. CONCLUSIONS: Duplex color-coded ultrasonography can accurately diagnose the site of VA occlusion.

Angiography, Digital Subtraction↗
PubMed2004

Quantitative magnetic detection of finger movements in patients with Parkinson's disease.

To develop a new measurement tool for quantitatively detecting the finger movement of a patient with Parkinson's disease (PD), we designed a magnetic sensing system consisting of a magnetic induction coil, a sensing coil, and a circuit unit. The sensing coil detects the inducted magnetic field that varies with the distance between the two coils, and the detected signals are demodulated in the circuit unit in order to obtain the variation voltage from the oscillation frequency. To obtain a coefficient for converting voltage to distance, we measured the output voltages for seven fixed finger positions of 12 normal volunteers. The voltage differences corresponding to the finger movement in 20 PD patients, six age-matched controls, and 12 normal volunteers were then recorded for 30s. To investigate the velocity and acceleration of the finger movement, we calculated their waveforms from the measured displacement waveform. We also detected the main frequency of the tapping rhythm by using a fast Fourier transform (FFT). The averaged amplitude of each waveform decreased with the disorder in the Hoehn-Yahr (HY) stage, while the averaged tapping frequency of PD patients did not have any correlation with this stage. It can be concluded that this magnetic sensing system can assess finger movement quantitatively.

Adult↗
PubMed2004

Administration of CD34+ cells after stroke enhances neurogenesis via angiogenesis in a mouse model.

Thrombo-occlusive cerebrovascular disease resulting in stroke and permanent neuronal loss is an important cause of morbidity and mortality. Because of the unique properties of cerebral vasculature and the limited reparative capability of neuronal tissue, it has been difficult to devise effective neuroprotective therapies in cerebral ischemia. Our results demonstrate that systemic administration of human cord blood-derived CD34(+) cells to immunocompromised mice subjected to stroke 48 hours earlier induces neovascularization in the ischemic zone and provides a favorable environment for neuronal regeneration. Endogenous neurogenesis, suppressed by an antiangiogenic agent, is accelerated as a result of enhanced migration of neuronal progenitor cells to the damaged area, followed by their maturation and functional recovery. Our data suggest an essential role for CD34(+) cells in promoting directly or indirectly an environment conducive to neovascularization of ischemic brain so that neuronal regeneration can proceed.

Animals↗