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Biomedical subjects

Y Katayama

Publications and source records attributed to Y Katayama.

At least 181 records · Page 10Linked to original sources
PubMed2000

Inhibitory effects of vesnarinone on cloned cardiac delayed rectifier K(+) channels expressed in a mammalian cell line.

Vesnarinone, a phosphodiesterase inhibitor, prolongs cardiac action potential duration by inhibiting the delayed rectifier K(+) current, I(K). We examined the effect of this agent on human ether-a-go-go related gene (HERG) and KvLQT1/minK K(+) channels heterologously expressed in human embryonic kidney 293T cells with the whole-cell patch-clamp technique. HERG channel current was inhibited by vesnarinone in a concentration-dependent manner, whereas KvLQT1/minK current was hardly affected by the drug. The inhibition of HERG current by vesnarinone became more prominent and faster as the membrane potential was more depolarized. The properties of inhibition could be described by a first order reaction between the drug and the channel that was apparently independent of HERG channel gating. Although the unbinding rate constant of the drug was constant, the apparent binding rate constant increased as the membrane was more depolarized and the drug concentration was raised. This model also could explain the fast recovery from the drug's effect at hyperpolarized potentials and its rate-dependent inhibition of HERG. Therefore, the effect of vesnarinone on the HERG-K(+) current could be adequately described by a simple kinetic model of drug-channel interaction.

Action Potentials↗
PubMed2000

Linkage of autosomal recessive hereditary spastic paraplegia with mental impairment and thin corpus callosum to chromosome 15A13-15.

To date, three loci for autosomal recessive hereditary spastic paraplegia (ARHSP) linked to chromosomes 8p12-q13, 16qter, and 15q13-15 have been characterized. We have clinically characterized 13 Japanese ARHSP families and performed genetic linkage analyses. All 13 families were classified as having the "complicated" form, which manifests with mental impairment and thin corpus callosum. Linkage to the 8p12-q13 and 16qter loci was excluded, although 10 of the 13 families showed marker data consistent with linkage to the 15q13-15 locus. The multipoint LOD score of the 10 families linked to chromosome 15 was above 9.00 in the 3-centimorgan segment flanked by D15S994 and D15S659, with a maximum multipoint LOD score of 9.68 at a position 1.2 centimorgans telomeric from D15S994 to D15S659. We have shown that ARHSP with thin corpus callosum, a subtype of recessive spastic paraplegia, maps to chromosome 15q13-15.

Adolescent↗
PubMed2000

Granulocyte colony-stimulating factor and lineage-independent modulation of VLA-4 expression on circulating CD34+ cells.

Although the use of allogeneic transplants of peripheral blood stem/progenitor cells (PBSCs) is increasing, the precise mechanism of PBSC mobilization has not yet been fully clarified. We examined the expression of some adhesion molecules on CD34+ cells from steady-state bone marrow (BM), granulocyte colony-stimulating factor (G-CSF)-mobilized PBSCs, and cytotoxic drugs plus G-CSF-mobilized PBSCs. Irrespective of mobilization method, very late antigen (VLA)-4 expression on circulating CD34+ cells was significantly lower than on steady-state BM CD34+ cells. To elucidate the influence of lineage commitment on VLA-4 expression of circulating CD34+ cells, we analyzed VLA-4 expression on different subsets of CD34+ cells with or without CD33, CD38, CD5, or CD10 antigens, or Glycophorin A in G-CSF-mobilized PBSCs and steady-state BM from related donors, using 3-color flow cytometry. VLA-4 on circulating CD34+ subsets was less expressed than on each corresponding subset of steady-state BM CD34+ cells. Furthermore, VLA-4 positive rates showed no significant difference among the CD34+ subsets. Finally, the data comparing CD34+ cells from steady-state and G-CSF-mobilized PBSCs revealed no differences in terms of VLA-4 expression. These data suggest that reduced expression of VLA-4 may be a result of peripheralization of CD34+ cells from bone marrow, which occurs in a G-CSF- and lineage-independent fashion.

Anti-Allergic Agents↗
PubMed2000

[First documentation of transfusion-associated babesiosis in Japan].

A 40-year-old man received blood transfusion in December 1998 because of gastric bleeding from a peptic ulcer. One month later, he developed febrile hemolytic anemia. Administration of high doses of glucocorticoid significantly reduced the hemolysis, but did not cure the disease. To investigate the cause of the hemolysis, the patient was transferred to our hospital in May 1999. Giemsa-stained peripheral blood smears showed Babesia parasites in the red blood cells (RBC), and PCR analysis confirmed the presence of Babesia microti DNA. The parasitemia disappeared hematologically after 2 weeks of quinine and clindamycin therapy. However, parasite DNA was still detectable in the RBC. Although treatment with oral atovaquone was given for 2 weeks, parasitemia and febrile hemolysis recurred within a month after the last treatment. Fortunately, complete remission was obtained after a second 12-week course of therapy with quinine and clindamycin. PCR analysis revealed asymptomatic Babesia infection in one of eight samples from the original blood donor. The initial steroid therapy given to the patient without an accurate diagnosis seemed to have delayed augmentation of the specific antibodies (IgG) against Babesia microti, thus prolonging the parasitemia after the initial acute stage of babesiosis.

Adult↗
PubMed2000

[MALT lymphoma producing IgG-kappa type M-protein].

A 72-year-old woman, who has been administered prednisolone and azathioprine with diagnoses of idiopathic thrombocytopenic purpura (ITP) and autoimmune hepatitis (AIH), underwent a complete medical examination because of monoclonal gammopathy (IgG-kappa). Tumors were found in the ileum and descending colon. Pathological examination of biopsy specimens suggested a diagnosis of marginal zone B-cell lymphoma of the MALT type with a high-grade component. Flow cytometric analysis by two-color staining revealed that the neoplastic B cells expressed CD38, CD19, IgG and kappa, but not CD5 or CD10. There were no abnormal plasma cells in bone marrow smears. The patient achieved complete remission after receiving three cycles of THP-COP chemotherapy, which resulted in a decrease of the IgG level to within the normal range. These findings indicated that monoclonal IgG-kappa might be produced by lymphoma cells. However, the relationship of the immunosuppressive agents to the pathogenesis of the MALT lymphoma remains to be clarified.

Aged↗
PubMed2000

[Deep brain stimulation(DBS) therapy for parkkinson,s disease].

During the last decade, it has become increasingly clear that DBS represents a useful adjunct for therapies to control various symptoms of Parkinson's disease. The stimulation sites include the thalamic nucleus ventralis intermedius(Vim), globus pallidus internus(GPi) and subthalamic nucleus (STN). The clinical data of DBS therapy currently available from the literature, together with our own experience, are reviewed. The results of our double blinded evaluation of the effects of GPi and STN stimulation are also summarized. DBS therapy affords the best effect on tremor when the Vim is selected as the stimulation site. DBS therapy is also useful for controlling rigidity when the GPi or STN is stimulated. Improvement of bradykinesia may often be induced by DBS therapy involving the GPi or STN. Dopa-induced dyskinesia can be attenuated effectively by the direct and/or indirect effects of DBS therapy. Two advantages of GPi and STN stimulation were identified in our double blinded evaluation. Firstly, the stimulation can supplement a reduced action of levodopa during the off-period. It thus improves the patient's daily activities through attenuation of the motor fluctuations. Secondly, the stimulation can replace part of the action of levodopa during the on-period. It thus attenuates dopa-induced dyskinesia through a reduced dose of medication. More importantly, the stimulation improves the daily activities in dopa-intolerant patients who are being administered a small dose of levodopa because of unbearable side effects. In addition, GPi stimulation has its own inhibitory effect on dopa-induced dyskinesia.

Clinical Trials as Topic↗
PubMed2000

[Limited upper sternotomy for minimally invasive aortic valve replacement].

The practice of minimally invasive valve surgery remains controversial. From May 1998, we began minimal invasive aortic valve replacement through the limited upper sternotomy. This technique is simple and provides and easy approach for the aortic valve. From May 1998 to Jan 2000, we performed 15 cases of aortic valve replacement with the limited upper sternotomy approach. All patients received valve replacement with prosthetic valve. We also described a simple and easy air evacuation system to avoid air embolism, a serious problem with a limited operative field. Mean aortic cross clamping time was 79 min, mean cardiopulmonary bypass time was 106 min, and mean operation time was 207 min. It did not take too much time compared with the conventional approach. Mean extubation time was 62 min and mean bleeding 12 hours after the operation was 96 ml. No patient required blood transfusions. All patients but one walked the very next day after the operation. We believe this new method brings not only cosmetic benefits, but also results in excellent post-operative course.

Adult↗
PubMed2000

Allogeneic peripheral blood stem cell transplantation in 23 adult patients with hematologic malignancies: a single-center experience.

We describe a single-center experience of 23 consecutive patients (median age, 35 years) with hematologic malignancies who received allogeneic peripheral blood stem cell transplants (alloPBSCTs) from HLA-identical siblings. Ten patients had standard-risk disease and 13 had high-risk disease. Twenty-one patients received alloPBSCT as a primary transplant, and the remaining 2, with high-risk disease, as a second transplant after posttransplantation relapse. All donors received daily subcutaneous injections of granulocyte colony-stimulating factor at a dose of 10 microg/kg, and peripheral blood stem cells were collected by 1 to 3 aphereses. Median numbers of CD34+ and CD3+ cells infused were 5.8 x 10(6)/kg (range, 1.3-19.7 x 10(6)/kg) and 4.9 x 10(8)/kg (range, 1.9-8.6 x 10(8)/kg), respectively. Graft-versus-host disease (GVHD) prophylaxis consisted of cyclosporin A (CyA) and methotrexate (18 patients) or CyA and methylprednisolone (5 patients). Rapid hematologic engraftment was observed in 20 of the 23 patients. Median days to absolute neutrophil counts >0.5 x 10(9)/L and platelet counts >20 x 10(9)/L were 12 (range, 9-18 days) and 14 (range, 10-128 days), respectively. Acute GVHD of grade 2-4 was observed in 6 of 20 evaluable patients (30%) and extensive chronic GVHD in 8 of 15 evaluable patients (53%). Ten of the 23 patients (44%) were surviving in continuous complete remission 191 to 1492 days (median, 643 days) posttransplantation. Treatment-related death within 100 days posttransplantation was observed in 6 of the 23 patients (26%). Six of the 23 patients (26%) developed relapse at a median 81 days (range, 38-160 days) posttransplantation. Further study is needed to assess the precise benefits of alloPB-SCT compared with allogeneic bone marrow transplantation.

Adolescent↗
PubMed2000

[Secular trends of sex ratios at birth in Japan].

OBJECTIVE: To describe secular trends of change in sex ratio at birth in Japan during the 100 years from 1899 to 1998. METHODS: Data on sex ratios (number of males to females at birth by prefecture) from 1899 to 1998 were obtained from the vital statistics of Japan. We used moving averages (9-years averages) to minimize the effects of yearly fluctuation on the sex ratio and calculated simple linear regression coefficients to examine trends in change for the period between 1925 and 1969 and between 1970 and 1998. RESULTS: The male: female sex ratio in Japan increased during the period through 1925 to about 1970 and thereafter decreased. The increase was the case for all prefectures with few exception, while these but Fukushima, Ibaraki, Fukui, Yamanashi and Kumamoto demonstrated subsequent decrease. The prefectures with strong decrease in the sex ratio from about 1970 at largely distributed facing the Sea of Japan; e.g. Akita, Toyama, Ishikawa, Kyoto, Shimane and Fukuoka. CONCLUSION: Our study confirmed a decline in the male: female sex ratio at birth in recent decades in Japan as a whole and in most prefectures. Although we do not know whether this is an effect of environmental pollution due to chemical substances, monitoring of secular trends in sex ratios should be continued with due attention to counsel to government.

Birth Rate↗
PubMed2000

[Immunoadsorption therapy with TR-350 (tryptophan column) for Guillain-Barré syndrome: investigation including serum antiganglioside antibody assay].

Immunoadsorption therapy (IAT) using TR-350 was performed for 14 patients with Guillain-Barré syndrome (GBS). Presence of serum antiganglioside antibodies (AGA) was investigated in all the patients in the acute phase. In 14 patients studied, 6 men and 8 women, ages from 24 to 74 years(mean, 42.5 years), 7 patients had suffered from common cold and 3 from diarrhea before neurological onset. Ophthalmoplegia was seen in 6 patients, facial palsy in 6, bulbar palsy in 3 and cerebellar sign in 2. Functional grade scores (FGS) by Hughes et al. of the patients were from 5 to 1 (mean, 3.3). In 4 patients, whose FGS were 1 or 2, IAT were performed, because of worsting of bulbar palsy, bilateral facial palsy and limb weakness. Relapse occurred in one patient. IAT was started from 2 to 18 days (mean, 8.4) after neurological onset and performed 3 to 14 times (mean, 7.5) for each patient. Mean FGS improved from 3.3 to 2.1 after IAT. The mean time to improve 1 grade was 10.3 days and mean time to improve 2 grades was 39.0 days. The mean FGS after 1 month was 1.4 and that after 3 months was 0.4. Some of 14 patients had elevated titers of AGA in sera in the acute phase. Four patients had anti-GQ1b IgG antibody and showed external ophthalmoplegia. One patient with anti-GD1b IgG antibody had cerebellar signs as well as peripheral neuropathy. Those AGAs decreased after IAT in parallel with improvement. IAT is an effective treatment in acute phase of GBS.

Acute-Phase Reaction↗
PubMed1999

Attachment of growth cones on substrate observed by multi-mode light microscopy.

Evanescent light illumination was introduced into a multi-mode microscope to construct a new type of total internal reflection fluorescence microscope (TIRFM). This microscope, capable of TIRFM, high resolution video-enhanced differential interference contrast (DIC), epifluorescence, interference reflection (IR) imaging, was combined with an image acquisition system for time-lapse microscopy. Neuronal growth cones of a rat hippocampal neuron were stained with membrane labeling fluorescence dyes (DiI or octadecyl rhodamine B). Dynamic changes of the cell substrate contact of the neuronal growth cone were observed using the multi-imaging capacities of this system. When growth cone regions were stimulated by pressure ejection of a high potassium solution, TIRFM intensity at the basal membrane of the growth cone increased, suggesting that basal membrane of growth cone approaches the glass substrate when excited. The approach of the ventral membrane to the substrate during excitatory stimulation was also observed with IR microscope. The functional importance of cell/substrate contact in growth cones is discussed.

Animals↗
PubMed1999

Organization of the genes involved in the ribulose monophosphate pathway in an obligate methylotrophic bacterium, Methylomonas aminofaciens 77a.

The 4.4-kb PstI fragment harboring the gene encoding 3-hexulose-6-phosphate synthase, rmpA, which was previously cloned from the chromosome of an obligate methylotroph, Methylomonas aminofaciens 77a, was investigated in detail. In addition to the rmpA gene, the fragment contained three open reading frames encoding transaldolase (rmpD), IS10-R (rmpI), and 6-phospho-3-hexuloisomerase (PHI) (rmpB). The rmpB gene product was overproduced in Escherichia coli cells, purified to homogeneity, and then enzymatically identified as PHI. The gene organization of the ribulose monophosphate pathway enzymes together with a transposon, IS10-R, is discussed from both evolutionary and regulatory aspects.

Aldehyde-Lyases↗
PubMed1999

Epinastine, a nonsedating histamine H1 receptor antagonist, has a negligible effect on HERG channel.

Terfenadine and astemizole rarely cause cardiac arrhythmias by suppressing the cardiac rapid delayed rectifier K+ channel encoded by the human ether-a-go-go-related gene (HERG). Epinastine, however, has not been reported to have the adverse effect. We have therefore compared the effects of epinastine, terfenadine and astemizole on HERG channels expressed in Xenopus oocytes. Terfenadine and astemizole suppressed the HERG current with IC50 of 431 nM and 69 nM, respectively. In contrast, 100 microM epinastine inhibited the HERG current by only 11+/-2.1%. These results may provide an explanation for the difference in the cardiotoxicity between different nonsedating histamine H1 receptor antagonists.

Animals↗
PubMed1999

Delayed administration of ethyl eicosapentate improves local cerebral blood flow and metabolism without affecting infarct volumes in the rat focal ischemic model.

The objective of this study was to assess whether delayed administration of ethyl eicosapentate has a favorable effect on cerebral blood flow and metabolism in rats suffering from cerebral infarction. Adult male Sprague-Dawley rats weighing 250-300 g were used. Left middle cerebral artery occlusion was induced for 2 h. After 24-h reperfusion, rats were treated with ethyl eicosapentate (100 mg kg(-1); ethyl eicosapentate treated) or saline (saline treated) by gavage, once a day for 4 weeks. After 4 weeks, local cerebral blood flow and local cerebral glucose utilization were measured autoradiographically, and infarction size was measured. In the ischemic side, the local cerebral blood flow and local cerebral glucose utilization values in the parietal cortex and the lateral caudoputamen, which constituted the ischemic core, were equivalent to zero in both groups. The peri-infarcted areas, i.e., the frontal cortex and medial caudoputamen, were significantly higher in the ethyl eicosapentate treated group than the saline treated group. In the non-ischemic side, ethyl eicosapentate treated group had a tendency to improve local cerebral blood flow and local cerebral glucose utilization values in a medial caudoputamen. These results suggest that ethyl eicosapentate treatment may be beneficial for maintaining cerebral circulation and metabolism except for infarction area after cerebral infarction.

Animals↗
PubMed1999

Analysis of 45 episodes of arterial occlusive disease in Japanese patients with congenital protein C deficiency.

Hereditary protein C deficiency is associated with a predisposition to venous thrombosis. It is not clear whether the deficiency is involved in arterial occlusion. In the present study, we screened for protein C amidolytic activity in patients admitted to the National Cardiovascular Center Hospital, and we identified among them 43 probands and 51 relatives with heterozygous protein C deficiency. Among them, 34 patients with heterozygous protein C deficiency had manifested 45 episodes of arterial occlusive disease. Venous thrombotic diseases were less common. In the examination of whether protein C deficiency hastens arterial occlusion, we found a significant difference (p =0.02) in the age at onset of acute myocardial infarction between the patients with protein C deficiency (n=10; 49.4+/-14.8 years) and a group of patients with normal protein C levels (n=42; 60.5+/-10.6 years). Acute myocardial infarction occurred before 40 years of age in a significantly greater proportion of the patients with protein C deficiency (3:10, 30%) as compared with the controls (2:42, 5%) (chi2=5.9, p=0.015). At the onset of atherothrombotic cerebral infarction the patients with protein C deficiency were significantly (p=0.022) younger (n= 11; 57.4+/-12.8 years) than those with normal protein C levels (n=48; 64.6+/-10.1 years). Venous thrombosis was the most frequent clinical manifestation (21 of 31 episodes) in the patients with antithrombin III deficiency (n=26; 68% of the total), who were admitted to our hospital. Thus, our study suggests that congenital protein C deficiency contributes to earlier onset of arterial occlusive diseases, especially acute myocardial infarction, in Japanese subjects.

Adult↗
PubMed1999

Real-time monitoring of glutamate transmitter release with anoxic depolarization during anoxic insult in rat striatum.

In vivo continuous real-time measurement of glutamate concentration was performed during anoxia using a dialysis electrode. By this method, the temporal resolution of the measurement of glutamate concentration was improved due to shortening of the time delay compared with the microdialysis method, and changes in the glutamate concentration were more clearly represented with greater reproducibility. After exposure to anoxia, the glutamate concentration showed biphasic changes. A relationship between the DC potential and release of glutamate was confirmed by the synchronization of anoxic depolarization (AD) with the 1st phase of glutamate release. Since the 1st phase disappeared and AD was delayed and suppressed by blocking Ca2+ influx, exocytosis is considered to play an important role in the construction of the 1st phase, which had a close relation with the occurrence of AD. Moreover, since blocking Ca2+ influx also had an effect on the glutamate release from the metabolic pool (2nd phase), reversed uptake may be involved with energy failure in the 1st phase, Ca2+ influx into the cell and rapid changes of the ionic environment associated with AD.

Animals↗
PubMed1999

Susceptibility to neuroleptic malignant syndrome in Parkinson's disease.

OBJECTIVE: To determine susceptibility to neuroleptic malignant syndrome (NMS) in patients with PD in relation to central monoamine metabolism. METHODS: CSF levels of homovanillic acid (HVA), 3-methoxy-4-hydroxy phenyletilene glycol (MHPG), and 5-hydroxyindole acetic acid (5-HIAA) were assayed in 98 PD patients (mean age, 77.2 years), including 11 patients with a prior NMS-like episode, by high-performance liquid chromatography with electrochemical detection. RESULTS: Patients with a previous NMS-like episode had worse parkinsonian disability as measured by Hoehn & Yahr scale (3.7 +/- 0.8 versus 3.0 +/- 1.1; p = 0.038) and lower CSF HVA levels (20.9 +/- 17.3 versus 44.7 +/- 22.2 ng/mL; p = 0.001) compared to those without, despite similar age, disease duration, and daily dosages of antiparkinsonian drugs between groups. Logistic regression analysis showed that the CSF HVA level (p = 0.008), but not 5-HIAA level (p = 0.621), was significantly and independently related to NMS, and that the MHPG level (p = 0.070) was tendentially associated with the disorder. Odds ratios (95% confidence intervals) corresponding to 10 ng/mL increment in CSF HVA, MHPG, and 5-HIAA levels were 0.30 (0.13 to 0.73), 4.03 (0.89 to 18.2) and 1.29 (0.47 to 3.58), respectively. CONCLUSIONS: Central dopaminergic and possible noradrenergic activity contributes to NMS development in an elderly population of PD patients. Measuring CSF levels of monoamine metabolites may provide a means for identifying NMS susceptibility in PD patients.

Aged↗