Biomedical subjects

H Wakita

Publications and source records attributed to H Wakita.

At least 19 recordsLinked to original sources

PubMed2003

Chronic cerebral hypoperfusion induces white matter lesions and loss of oligodendroglia with DNA fragmentation in the rat.

Cerebrovascular white matter lesions represent an age-related neurodegenerative condition that appears as a hyperintense signal on magnetic resonance images. These lesions are frequently observed in aging, hypertension and cerebrovascular disease, and are responsible for cognitive decline and gait disorders in the elderly population. In humans, cerebrovascular white matter lesions are accompanied by apoptosis of oligodendroglia, and have been thought to be caused by chronic cerebral ischemia. In the present study, we tested whether chronic cerebral hypoperfusion induces white matter lesions and apoptosis of oligodendroglia in the rat. Doppler flow meter analysis revealed an immediate reduction of cerebral blood flow ranging from 30% to 40% of that before operation; this remained at 52-64% between 7 and 30 days after operation. Transferrin-immunoreactive oligodendroglia decreased in number and the myelin became degenerated in the medial corpus callosum at 7 days and thereafter. Using the TUNEL method, the number of cells showing DNA fragmentation increased three- to eightfold between 3 and 30 days post-surgery compared to sham-operated animals. Double labeling with TUNEL and immunohistochemistry for markers of either astroglia or oligodendroglia showed that DNA fragmentation occurred in both of these glia. Messenger RNA for caspase-3 increased approximately twofold versus the sham-operated rats between 1 and 30 days post-surgery. Immunohistochemistry revealed up-regulation of caspase-3 in the oligodendroglia of the white matter, and also in the astroglia and neurons of the gray matter. Molecules involved in apoptotic signaling such as TNF-alpha and Bax were also up-regulated in glial cells. These results indicate that chronic cerebral hypoperfusion induces white matter degeneration in association with DNA fragmentation in oligodendroglia.

Animals↗

PubMed2001

Caudoputamen is damaged by hypocapnia during mechanical ventilation in a rat model of chronic cerebral hypoperfusion.

BACKGROUND AND PURPOSE: Postoperative brain dysfunction, such as delirium, is a common complication of anesthesia and is sometimes prolonged, especially in patients with cerebrovascular disease. In the present study we investigated the effect of hypocapnia during anesthesia on neuronal damage using a rat model of chronic cerebral hypoperfusion. METHODS: Chronic cerebral hypoperfusion was induced by clipping the bilateral common carotid arteries in male Wistar rats. Fourteen days after the operation, these animals were mechanically ventilated for 2 hours and then kept in suitable conditions for an additional 14 days. Twenty-four rats were assigned to 4 groups: those with chronic cerebral hypoperfusion with either hypocapnia or normocapnia during anesthesia, and those given sham operation with either hypocapnia or normocapnia. White matter lesions in the brain sections were evaluated with Klüver-Barrera staining. Proliferation of glial cells was estimated with the use of immunohistochemistry of glial fibrillary acidic protein, a marker for astroglia, and CD11b, a marker for microglia. Computer-assisted morphometry was applied to the immunohistochemical results of microtubule-associated protein 2 to evaluate the loss of neurons. RESULTS: The histological damage was localized almost exclusively in the white matter in the rats subjected to chronic cerebral hypoperfusion but without hypocapnia. Neuronal damage and astroglial proliferation occurred with aggravated white matter lesions in the caudoputamen in the rats with chronic cerebral hypoperfusion and hypocapnia. No lesions were observed in sham-operated rats with either hypocapnia or normocapnia. CONCLUSIONS: These results indicate that hypocapnia during anesthesia causes tissue damage in the caudoputamen, which may be responsible for long-lasting postoperative delirium in patients with stroke and/or dementia.

Anesthesia↗

PubMed2001

White matter lesions and alteration of vascular cell composition in the brain of spontaneously hypertensive rats.

There have been few studies on the white matter lesions of spontaneously hypertensive rats (SHR). From the point of view of hypertension and arteriosclerosis, white matter lesions were examined in SHR and stroke-prone SHR (SHRSP), and were then compared with Wistar-Kyoto (WKY) rats. The vasculopathy was analyzed by morphometric immunohistochemistry for collagen and smooth muscle actin. Both SHR and SHRSP had hypertension at > or = 12 weeks of age, and the latter developed severe white matter lesions at 20 weeks. Immuno- histochemistry revealed proliferation of microglia in the white matter and an increase in smooth muscle actin in the vessels of SHRSP compared with the WKY rats and SHR, but there were no changes in the collagen. These results indicate a role of hypertension in the pathogenesis of white matter lesions. However, genetic difference may also be responsible since SHR and SHRSP showed similar hypertension.

Actins↗

PubMed2001

New method of the chemical state imaging by EPMA-EXEFS.

A novel two dimensional imaging technique of the chemical bonding state was developed by combining the extended X-ray emission fine structure method with an electron probe X-ray microanalyzer mapping technology. With this method, chemical state images of some aluminum standard samples were obtained. It was confirmed that the obtained images provide correct information of chemical states.

Journal Article↗

PubMed2001

Effects of photocatalytic reactions on marine plankton: titanium dioxide powder as catalyst on the body surface.

Photocatalytic effects of TiO2 powder on marine plankton were examined by the use of either brine shrimp Artemia salina or noxious red tide flagellate Chattonella antiqua as a probe. After UV (365 nm) irradiation for ca. 1 hour, A. salina stopped moving and the body surface was completely covered by TiO2 powder. Similar photoirradiation of C. antiqua, on the other hand, induced deformation of the body from spindle to round shape within 20 minutes. The deformed C. antiqua recovered to normal shapes, when the cells were kept in the same conditions but without UV irradiation for more than 40 minutes. On the prolonged UV irradiation (more than 100 minutes), however, the cells burst and came to annihilation. The photocatalytic reactions of TiO2 on the body surface are thus concluded to induce fatal damages to these microorganisms.

Animals↗

PubMed2001

Chronic cerebral hypoperfusion induces MMP-2 but not MMP-9 expression in the microglia and vascular endothelium of white matter.

White matter lesions are closely associated with cognitive impairment and motor dysfunction in the aged. To explore the pathophysiology of these lesions, the authors examined the expression of matrix metalloproteinase-2 (MMP-2) and MMP-9 in the white matter in a rat model of chronic cerebral hypoperfusion. After bilateral clipping of the common carotid arteries, myelin staining revealed demyelinating changes in the optic tract and the corpus callosum on day 7. Zymographic analyses indicated an increase in the level of MMP-2, but not MMP-9, after the hypoperfusion. Immunohistochemical analyses revealed the presence (most abundantly on day 3) of MMP-2-expressing activated microglia in the optic tract and corpus callosum. In contrast, the capillary endothelial cells expressed MMP-2 later. IgM-immunoreactive glial cells were absent in the sham-operated animals, but were present in the hypoperfused animals by day 3, reflecting the disrupted blood-brain barrier. These findings suggest that the main sources of the elevated MMP-2 were the microglia and the endothelium, and that these cells may contribute to the remodeling of the white matter myelin and microvascular beds in chronic cerebral hypoperfusion.

Animals↗

PubMed2001

X-ray absorption spectral analyses by theoretical calculations for TiO2 and Ni-doped TiO2 thin films on glass plates.

Ni L- and Ti L-edge as well as Ti K-edge X-ray absorption experiments for TiO2 thin films and Ni-doped TiO2 thin films coated on glass plates were performed using synchrotron radiation to investigate the structures around Ni and Ti ions in the films. The obtained spectra were compared with the results of theoretical calculations. It has consequently been found that the spectral features were affected by a change in the oxidizing form of Ni ions due to hydrogen reduction, by the charge variation and/or slight orbital splitting of Ti ions, and by the magnitude of the interaction between the center Ti ion and neighboring Ti ions.

Journal Article↗

PubMed2000

Cyclooxygenase-2 is induced in microglia during chronic cerebral ischemia in humans.

Cyclooxygenase-2 (COX-2) is known to be up-regulated in ischemic rodent brains, but only little information is available for the human brain. Using immunohistochemistry for COX-2, we investigated brains from control subjects and from patients with cerebrovascular diseases. COX-2 was markedly up-regulated in the neurons and endothelial cells in acute cerebral infarction, but was detected sparsely at chronic stages in these cellular compartments. In contrast, COX-2 immunoreactivity in glial cells was localized to the perinuclear region even in control brains. This immunolabeling was more intense and occurred also in the glial cytoplasm in the brains with chronic cerebral ischemia such as Binswanger's disease. Double-labeling immunohistochemistry confirmed that COX-2-immunoreactive glia were mostly microglia. These results indicate that prostanoid synthesis is up-regulated in microglia during chronic cerebral ischemia, and that these cells may be involved in tissue repair or inflammation-mediated cell responses.

Aged↗

PubMed2000

Dose-escalation study of CHOP with or without prophylactic G-CSF in aggressive non-Hodgkin's lymphoma.

BACKGROUND: CHOP is accepted as the gold standard for first line chemotherapy of aggressive non-Hodgkin's lymphoma (NHL). A dose-escalation study of CHOP was conducted to determine the maximal tolerated dose (MTD) and toxicity profile of CHOP at three-week intervals with or without prophylactic recombinant human granulocyte colony-stimulating factor (rHuG-CSF) in patients with aggressive NHL. PATIENTS AND METHODS: The doses of drugs were escalated from 50 mg/m2 to 70 mg/m2 for doxorubicin and from 750 mg/m2 to 2250 mg/m2 for cyclophosphamide, with conventional doses of vincristine and oral prednisolone. After the MTD was determined without rHuG-CSF, dose escalation was conducted with prophylactic rHuG-CSF. RESULTS: Thirty-three patients with NHL were enrolled into the study. The MTD without prophylactic rHuG-CSF was 70 mg/m2 of doxorubicin and 1250 mg/m2 of cyclophosphamide, with neutropenia as a dose-limiting toxicity. The MTD with prophylactic rHuG-CSF was 70 mg/m2 of doxorubicin and 2250 mg/m2 of cyclophosphamide. The overall response rate was 100% (76% complete response and 24% partial response). Progression-free survival and overall survival at five years were 45% and 66%, respectively. CONCLUSIONS: Significant dose escalation of doxorubicin and cyclophosphamide was feasible with prophylactic rHuG-CSF. The efficacy of dose-escalated CHOP should be compared with that of standard CHOP.

Adolescent↗

PubMed2000

Vascular cell components of the medullary arteries in Binswanger's disease brains: a morphometric and immunoelectron microscopic study.

BACKGROUND AND PURPOSE: It has been hypothesized that fibrohyalinosis of the medullary arteries may cause white matter lesions in Binswanger's disease (BD). However, previous reports have been inconsistent on the pathological alterations of the cellular components, which may vary in terms of vessel sizes. We therefore quantitatively examined vasculopathy in the medullary arteries of a defined caliber in BD brains with a quantitative technique. METHODS: A total of 20 brains were examined: 10 from patients with BD and 10 from age-matched nonneurological control patients. The alterations in the vascular cell components were examined with quantitative immunohistochemistry and immunoelectron microscopy for collagen and smooth muscle actin. RESULTS: The nonneurological control patients showed no white matter lesions. In contrast, the patients with BD invariably had marked white matter lesions, as well as fibrohyalinosis of the medullary arteries. The ratio of the area immunolabeled for collagen type I and type IV to the cross-sectional area was 2-fold higher in the BD patients than in the control patients, regardless of the vessel caliber (P<0.005). Although the ratio for smooth muscle actin in the BD brains was increased in arteries of <100 microm (P<0.0001), there was no corresponding increase in the arteries of >100 microm. However, in the ultrastructure of these vessels, the cell bodies immunolabeled for smooth muscle actin were hypertrophic and segregated from each other by proliferated fibrils. The basal lamina appeared multilayered, and the endothelial cells were swollen. Collagen type I and type IV immunoreactive fibrils also proliferated in the pericapillary space of the BD brains. CONCLUSIONS: The proliferation of collagen fibrils in the media and adventitia of the blood vessels in BD brains was not specific to small arteries and arterioles but also occurred in the pericapillary spaces. Pericapillary sclerosis, smooth muscle cell proliferation in the terminal arterioles, and their morphological transformation in the proximal arteries may alter the shear rates and thus cause profound microcirculatory disturbances in BD brains.

Actins↗

PubMed2000

Effects of an antithrombin drug in patients with subacute exacerbations of Binswanger disease.

The blood coagulation system has been shown to be activated in subacute exacerbations of Binswanger disease (BD). In our previous study, the antithrombin drug argatroban t ameliorated the neurological exacerbations in a BD patient with antiphospholipid antibody syndrome. We have further examined the therapeutic efficacy of argatroban in 3 BD patients with subacute exacerbations, but without any immune-mediated prothrombotic complications. In 1 out of these 4 patients, treatment with sodium ozagrel, an antiplatelet drug was applied, but was ineffective. In all patients, argatroban treatment reduced the levels of the hemostatic markers, with a corresponding improvement in cognitive dysfunction and gait disorders. These results suggest that the antithrombin effect is true also for BD patients not compromised by the immune-mediated prothrombotic condition.

Acute Disease↗

PubMed2000

Study of dose escalation and sequence switching of administration of the combination of docetaxel and doxorubicin in advanced breast cancer.

The objectives of the present study were to evaluate whether a schedule-dependent pharmacokinetic and/or pharmacodynamic interaction exists between two sequences of docetaxel and doxorubicin administration and to determine the maximal tolerated dose (MTD) of this combination. Patients with chemotherapy-naïve metastatic or recurrent advanced breast cancer were enrolled. In the crossover design, tandem dose escalation of docetaxel and doxorubicin was performed. Docetaxel, in doses ranging from 50-70 mg/m2, was administered for 1 h by drip infusion either just before or after a 5-min bolus i.v. injection of doxorubicin at dosages from 40-50 mg/ m2. The sequence of drug administration was switched after the first course in each patient, and the sequence of drug administration thereafter depended on the patient's choice. Twenty-five patients were initially assessable for toxicity. The MTD in the sequence of doxorubicin after docetaxel was 40 and 50 mg/m2, respectively, with the dose-limiting toxicity of neutropenia. On the other hand, the MTD of the sequence of docetaxel after doxorubicin was 70 and 50 mg/m2, respectively. The dose-limiting toxicities in this sequence were neutropenia and diarrhea. Duration of grade 4 neutropenia in the sequence of docetaxel followed by doxorubicin was significantly longer than that in the alternate sequence (P = 0.0062). However, there was no difference in pharmacokinetic parameters of docetaxel, doxorubicin, and doxorubicinol between the two sequences. The sequence of 50 mg/m2 doxorubicin followed by 60 mg/m2 docetaxel is recommended for subsequent clinical trials for practical reasons.

Adult↗

PubMed2000

Good prognosis of patients with acute promyelocytic leukemia who achieved second complete remission (CR) with a new retinoid, Am80, after relapse from CR induced by all-trans-retinoic acid.

A new synthetic retinoid, Am80, is effective in treating acute promyelocytic leukemia relapsed from all-trans-retinoic acid-induced complete remission (CR). We report here the long-term clinical outcomes of patients who achieved second CR with Am80. Of 24 evaluable patients, 14 achieved a second CR by Am80 therapy. Of those patients, 4 relapsed within 6 months, despite subsequent consolidation chemotherapy. Six patients underwent sibling or unrelated HLA-matched allogeneic bone marrow transplantation (BMT), and 4 are alive without relase for more than 49 months after achieving second CR. Four of 8 patients who did not receive BMT are alive without relapse for more than 49 months. Promyelocytic leukemia-retinoic acid receptor alpha (PML-RAR alpha) fusion transcript was undetectable by reverse transcriptase-polymerase chain reaction in all living patients. Therefore, if patients achieve second CR with Am80 and HLA-matched donors are available, BMT is the treatment of choice. However, it is noteworthy that CR was maintained for more than 49 months in half of the patients who did not receive BMT.

Adult↗

PubMed1999

Activation of epidermal growth factor receptor promotes late terminal differentiation of cell-matrix interaction-disrupted keratinocytes.

The biological effects of epidermal growth factor receptor (EGFR) activation may differ between epidermal suprabasal and basal keratinocytes, since growth factors are mitogenic in adherent cells only in the presence of cell-extracellular matrix (ECM) interaction. To investigate biological effects of EGFR activation on keratinocytes without cell-ECM interaction, we cultured normal human keratinocytes on polyhydroxyethylmethacrylate-coated plates, which disrupt cell-ECM but not cell-cell interaction. The cells initially expressed keratin 10 (K10) and then profilaggrin, mimicking sequential differentiation of epidermal suprabasal keratinocytes. The addition of EGF or transforming growth factor-alpha promoted late terminal differentiation (profilaggrin expression, type 1 transglutaminase expression and activity, and cornified envelope formation) of the suspended keratinocytes, while suppressing K10 expression, an early differentiation marker. These effects were attenuated by EGFR tyrosine kinase inhibitor PD153035 or an anti-EGFR monoclonal antibody, whereas protein kinase C inhibitors H7 and bisindolylmaleimide I or mitogen-activated protein kinase/extracellular signal-regulated kinase kinase inhibitor PD98059 abolished profilaggrin up-regulation but not K10 suppression. Since the antidifferentiative role of EGFR on cell-ECM interaction-conserved keratinocytes has been well documented, our results indicate that the biological effects of EGFR on keratinocytes are influenced by cell-ECM interaction and suggest that EGFR activation promotes rather than inhibits the terminal differentiation of suprabasal epidermal keratinocytes.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed1999

A cyclooxygenase-2 inhibitor attenuates white matter damage in chronic cerebral ischemia.

The effects of nimesulide, a cyclooxygenase-2 inhibitor, were examined during chronic cerebral hypoperfusion. After bilateral ligation of the common carotid arteries in 30 rats, 21 received dosages of 2 or 5 mg/kg nimesulide daily and nine received vehicle daily for 14 days. The serum was then analyzed biochemically, and pathological changes were estimated in the white matter by the emergence of major histocompatibility complex (MHC) antigen-immunoreactive activated microglia and white matter lesions. In the vehicle-treated animals, activated microglia and white matter lesions were observed. Following treatment with either 2 or 5mg/kg nimesulide, the magnitude of these changes was reduced (p < 0.001) without significant side effects. These results indicate a potential use for cyclooxygenase-2 inhibitors in cerebrovascular disease.

Analysis of Variance↗

PubMed1999

Effects of antithrombin on Binswanger's disease with antiphospholipid antibody syndrome.

The authors present a family with Binswanger's disease (BD) and antiphospholipid antibody syndrome (APAS). In one patient from this family, lupus anticoagulant and high levels of hemostatic markers were detected. The presence of BD and the clinicobiological improvements observed after antithrombin treatment in this patient are peculiar to this familial case of APAS.

Antiphospholipid Syndrome↗

PubMed1999

Coagulation activation in patients with Binswanger disease.

BACKGROUND: A hypercoagulable state is often associated with an acute stroke in cerebrovascular disease (CVD). However, in Binswanger disease (BD), no information is available on the coagulation-fibrinolysis pathway except for the presence of high plasma fibrinogen levels. OBJECTIVE: To determine the association of BD and coagulation-fibrinolysis pathway activation. PATIENTS AND METHODS: We examined the levels of fibrinogen, thrombin-antithrombin complex, prothrombin fragment(1+2), and cross-linked D-dimer in 17 patients with BD, 24 neurologic patients without CVD, and 26 patients with lacunar infarction in either the acute or chronic stage. RESULTS: As compared with the non-CVD and lacunar infarction groups, the patients with BD had significantly elevated levels of thrombin-antithrombin complex (P<.001), prothrombin fragment(1+2) (P<.05), and cross-linked D-dimer (P<.01). There was also a significant increase in fibrinogen levels compared with the non-CVD group (P<.05). In the BD group, 8 patients in stable condition (ie, those without obvious neurologic deficits in the past 3 months) showed normal levels or a mild increase in their fibrinogen, thrombin-antithrombin complex, prothrombin fragment(1+2), or cross-linked D-dimer levels. In contrast, 9 patients with BD with a subacute aggravation of their focal or subcortical cerebral functions (deteriorating group) showed a significant increase in their thrombin-antithrombin complex levels compared with the stable patients (P<.01). Similarly, the fibrinogen, prothrombin fragment(1+2), and cross-linked D-dimer levels were elevated in the deteriorating patients, but this trend did not reach statistical significance. CONCLUSIONS: These results indicate that the coagulation-fibrinolysis pathway is activated in patients with BD with a subacute aggravation. Coagulation activation may result in the formation of microthrombi and microcirculatory disturbances in the brains of these patients, and thus promote further biological and neurologic insults.

Aged↗

PubMed1999

Vascular changes in white matter lesions of Alzheimer's disease.

The pathogenesis of white matter lesions observed in Alzheimer's disease (AD) is not completely clear. We tested the hypothesis that white matter lesions are correlated with medullary artery sclerosis rather than with amyloid angiopathy. A total of 57 brains were examined, including 39 derived from patients with AD and 13 from patients with Binswanger's disease (BD) along with 5 from non-neurological patients. Moderate or severe amyloid deposits in the meningocortical segment were observed in 32 out of 39 AD patients (82.1%), and in 2 out of 13 BD patients (15.4%). These deposits were not observed in the white matter segment, except for 2 patients with AD. The BD patients invariably had marked white matter lesions and fibrohyalinosis in the medullary arteries, with a mean sclerotic ratio of 48.1%. In contrast, the AD patients had mild or moderate white matter lesions and a sclerotic ratio of 37.9%, which was significantly greater than the controls. The scores for white matter lesions were correlated with the sclerotic ratio of the medullary arteries, but not with the ages of onset or the scores for amyloid angiopathy. Although amyloid angiopathy is an independent risk of white matter lesions, its role is limited in the pathogenesis of those associated with AD. Wall thickening of the medullary arteries, likely due to fibrohyalinosis, is closely correlated with the white matter lesions in AD, thus indicating a heterogeneity in its etiology.

Aged↗