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Biomedical subjects

N Takeda

Publications and source records attributed to N Takeda.

At least 109 records · Page 6Linked to original sources
PubMed2000

Effects of pre-flocculectomy on Fos expression and NMDA receptor-mediated neural circuits in the central vestibular system after unilateral labyrinthectomy.

In this study in order to elucidate the role of the flocculus in the whole process of vestibular compensation from the very early stage to the chronic stage, we first examined unilateral labyrinthectomy (UL)-induced spontaneous nystagmus (SN), a behavioral marker of vestibular compensation, and Fos expression, a marker of neural activity, in the vestibular brainstem in pre-unilateral flocculectomized (pre-UF) rats. UL in pre-UF rats caused more severe vestibulo-ocular deficits at the very early stage than it did in floccular-intact rats. Fos expression occurred in the medial vestibular nucleus contralateral to the UL side (contra-MVe) and the prepositus hypoglossal nucleus ipsilateral to the UL side (ipsi-PrH), whereas Fos expression was never seen after UL in floccular-intact rats. Therefore, these findings suggest the UL in pre-UF rats activates the contra-MVe and ipsi-PrH neurons and causes great imbalance between intervestibular nuclear activities, inducing more severe vestibular symptoms at the very early stage than those in floccular-intact rats. Next, we observed MK801 (a specific antagonist on the NMDA receptor)-induced SN in pre-UF rats at the chronic stage after UL. MK801 administration to pre-UL rats caused reappearance of SN even 14 days after UL, while administration to floccular-intact rats at a post-UL interval of 14 days never induced decompensation. Therefore, these findings suggest that the flocculus takes part in NMDA receptor-mediated neural circuits involved in vestibular compensation and modifies the neural interactions at the chronic stage after UL. Taken together, those results suggest that the flocculus plays important roles in the restoration of a balance between intervestibular nuclear activities, to reduce vestibular symptoms during the very early stage, and thereafter in the modification of NMDA receptor-mediated neural interactions in the central vestibular system at the chronic stage.

Animals↗
PubMed2000

Augmentation of immune responses to hepatitis E virus ORF2 DNA vaccination by codelivery of cytokine genes.

DNA vaccines encoding a viral structural protein have been shown to induce antiviral immune responses and provide protection against subsequent viral challenge. In the present study we show that DNA immunization with a plasmid expressing the hepatitis E virus ORF2 structural protein (pcDNA-ORF2) induced low levels of long-lasting antibody responses in the murine model. The use of plasmids expressing interleukin-2 (IL-2) and granulocyte-macrophage colony-stimulating-factor (GM-CSF) in conjunction with pcDNA-ORF2 enhanced the antibody responses generated by pORF-2. We further show that the immune responses generated by plasmid pcDNA-ORF2 can be boosted with virus-like particles composed of the ORF2 protein expressed through a baculovirus expression system.

Animals↗
PubMed2000

Aging effects on motor units in the human thyroarytenoid muscle.

OBJECTIVES: To determine whether age differences are present in the human laryngeal thyroarytenoid muscle that would indicate that different normative values would be needed for identifying motor unit abnormalities. STUDY DESIGN: Twenty-six consecutively recruited healthy subjects between the ages of 21 and 72 years participated in a laryngeal electromyography study. METHODS: Bipolar needle electrodes were used to record motor unit action potentials from several locations in the right and left thyroarytenoid muscles of each subject. The duration of a motor unit was measured when at least 10 firings of the same motor unit could be identified. On the average, four units were measured per muscle. RESULTS: In the subjects less than 60 years of age, motor unit duration did not increase significantly with age. However, motor units from subjects greater than 60 years of age had longer durations than those from subjects less than 60 years of age (P < .00005), and 25% of the units measured in subjects greater than 60 years of age had longer durations than any of the units measured in subjects less than 60 years of age. Further, the older subjects differed from each other in their mean unit durations (P < .0001). In subjects less than 60 years of age, significantly longer durations were found for units innervated by the longer, left-side recurrent laryngeal nerve in comparison with the right-side nerve (P = .005). CONCLUSIONS: Different mean and SD values should be used for patients less than and greater than 60 years of age and for the right and left sides, when evaluating motor units in the thyroarytenoid muscles.

Adult↗
PubMed2000

Expression of recombinant capsid proteins of chitta virus, a genogroup II Norwalk virus, and development of an ELISA to detect the viral antigen.

The second open reading frame (ORF2) gene of the Chitta virus (CHV) was cloned to construct a recombinant baculovirus. The CHV ORF2 is predicted to encode a capsid protein of 535 amino acids (aa). CHV showed a high aa identity in the capsid region with genogroup II Norwalk virus (NV) (65-85%), but a low aa identity with genogroup I NV (44-46%). Phylogenetic analysis of the ORF2 gene demonstrated that CHV is genetically closely related to the Hawaii virus included in genogroup II NV. The recombinant capsid protein of CHV (rCHV) self-assembled to form empty virus-like particles (VLPs) when expressed in insect cells with the recombinant baculovirus. An enzyme-linked immunosorbent assay (ELISA) based on antisera to rCHV was developed to detect CHV antigen in stools. The antigen ELISA appeared to be highly specific to both rCHV and CHV-like strains. In addition, combined use of antigen ELISAs using antibodies against two antigenically distinct recombinant VLPs, the recombinant Chiba virus (rCV) and recombinant Seto virus (rSEV), enabled us to determine the genetic as well as antigenic relationship among these three viruses.

Animals↗
PubMed2000

Relations of insulin resistance and serum concentrations of estradiol and sex hormone-binding globulin to potential breast cancer risk factors.

There is a hypothesis that hyperinsulinemia or insulin resistance may be a mediator for breast cancer risk factors. On the other hand, some, but not all, of the well-known risk factors of breast cancer have been associated with serum estrogen concentrations. We assessed the relationships of potential breast cancer risk factors to indicators of insulin resistance, fasting plasma insulin concentration and homeostasis model assessment insulin resistance (HOMA-R), in 88 postmenopausal Japanese women. We also examined whether insulin resistance would explain the association of breast cancer risk factors with serum estradiol and sex hormone-binding globulin (SHBG). Information on potential breast cancer risk factors, such as demographic characteristics, smoking and drinking habits, diet, exercise, menstrual and reproductive factors, was obtained by self-administered health questionnaire including a validated semiquantitative food frequency questionnaire. Body mass index (BMI) was significantly correlated with the ratio of estradiol to SHBG (Spearman r = 0.30, P = 0.0004), fasting plasma insulin (r = 0.45) and HOMA-R (r = 0.43, P = 0.0001) after controlling for age. The correlations were still significant between BMI and estradiol / SHBG ratio (r = 0.21, P = 0.047) after controlling for fasting plasma insulin and between BMI and fasting plasma insulin (r = 0.40, P = 0. 0001) as well as HOMA-R (r = 0.38, P = 0.0003) after controlling for estradiol / SHBG ratio. There is a possibility that effect of BMI on breast cancer risk is mediated by both insulin resistance and estrogen metabolism.

Aged↗
PubMed2000

[A trial of amantadine for the treatment of influenza A infection in children].

We administered amantadine to 52 children for therapy and 3 children for prophylaxis of influenza A infection from January to March 1998. Among the 23 children in the therapy group with proven influenza A/H3N2 infection, 15 patients (60%) allayed fever within 3 days but 9 (40%) had persistent fever for more than 4 days after administration of amantadine. Seven of these nine patients (40%) received amantadine within 2 days after the onset of fever. Two of these nine had secondary bacterial infections. One child had insomnia as side effect. We concluded that administration of amantadine for therapy is safe and effective, if given to patients without secondary bacterial infections in the first 48 hours of the illness.

Adolescent↗
PubMed2000

[Comparison between cytomegalovirus hepatitis and Epstein-Barr virus hepatitis in healthy adults].

In order to determine the factors responsible for the differentiation of cytomegalovirus (CMV) hepatitis and Epstein-Barr virus (EBV) hepatitis in previously healthy adults, the clinical features and laboratory data of both types of hepatitis were retrospectively analyzed. CMV hepatitis showed a tendency to increase in our department. In comparison with EBV hepatitis, CMV hepatitis occurred in significantly older hosts than EBV hepatitis. We found that lymphadenopathy, cough and sore throat was more common in EBV hepatitis than in CMV hepatitis. The number of peripheral white blood cell count and atypical lymphocytes, and serum GOT, GPT, LDH and CRP levels of CMV and EBV hepatitis showed no significant differences.

Adolescent↗
PubMed2000

Identification of an epitope common to genogroup 1 "norwalk-like viruses".

A panel of 10 monoclonal antibodies (MAbs) to recombinant Norwalk virus (NV) capsid protein were tested in competition enzyme-linked immunosorbent assays. Patterns of competition indicated that these MAbs recognize six to eight epitopes covering five nonoverlapping regions of the capsid protein. A single epitope, recognized by NV MAbs NV3901, NV3912, and NV2461 was found to occur in the majority of genogroup 1 (G1) but not genogroup 2 (G2) "Norwalk-like viruses" (NLVs). This observation supports the subdivision of human NLVs into two genogroups and provides an assay for the rapid identification of G1 NLVs in fecal specimens.

Antibodies, Monoclonal↗
PubMed2000

Molecular cloning, expression, and antigenicity of Seto virus belonging to genogroup I Norwalk-like viruses.

The viral capsid protein of the Seto virus (SeV), a Japanese strain of genogroup I Norwalk-like viruses (NLVs), was expressed as virus-like particles using a baculovirus expression system. An antigen detection enzyme-linked immunosorbent assay based on hyperimmune antisera to recombinant SeV was highly specific to homologous SeV-like strains but not heterologous strains in stools, allowing us type-specific detection of NLVs.

Animals↗
PubMed2000

Interaction of recombinant norwalk virus particles with the 105-kilodalton cellular binding protein, a candidate receptor molecule for virus attachment.

Norwalk virus (NV), responsible for outbreaks of acute gastroenteritis, comprises the species of the genus Norwalk-like viruses in the family Caliciviridae. Although the study of the molecular biology of NV has been hampered by a lack of culture systems or small experimental animal models, virus-like particles (VLPs) generated with recombinant baculoviruses harboring the capsid protein gene of NV provide a useful tool for investigating NV-cell interactions. In this study, the attachment of the recombinant VLPs derived from the Ueno virus (UEV), a strain belonging to the genogroup II NVs, to mammalian and insect cells was examined. Kinetic analyses of the binding of the recombinant VLPs of the UEV (rUEVs) to Caco-2 cells demonstrated that the binding was specific and occurred in a dose-dependent manner. Approximately 7.5% of the prebound rUEVs were internalized into the Caco-2 cells. Enzymatic and chemical modification of Caco-2 cell surface molecules suggested that the binding was directly mediated by a protein-protein interaction. A virus overlay protein-binding assay (VOPBA) indicated that rUEVs appeared to bind to a 105-kDa molecule, designated as the NV attachment (NORVA) protein. Furthermore, the assay indicated that its native conformational structure was indispensable for the binding activity. In Caco-2 cells, the NORVA protein was detected when VOPBA was carried out with the VLPs from Seto and Funabashi viruses, which are serologically different NVs from UEV, used as probes. The binding of rUEVs to NORVA protein was also observed in six mammalian cell lines other than Caco-2. These data suggest that the attachment of NV to mammalian cells is mediated by NORVA protein, which is ubiquitously expressed in the mammalian cells. The present study is the first report on the role of the cellular molecule in the binding of recombinant VLPs of NV.

Amino Acid Sequence↗
PubMed2000

Transthoracic ultrasonic visualisation of coronary aneurysm, stenosis, and occlusion in Kawasaki disease.

OBJECTIVE: To determine the sensitivity and specificity of our transthoracic echocardiographic technique using high frequency (7.5 MHz) transducers for identification of the presence and type of coronary artery disease in patients with Kawasaki disease. DESIGN: The results of the prospective echocardiographic study in each of seven segments of the four major coronary arteries were compared with the selective coronary angiograms. SETTING: Kitasato University Hospital. SUBJECTS: 60 patients with Kawasaki disease, ranging in age from 8.0 months to 22 years (median, 6.0 years). RESULTS: Adequate echocardiographic images were obtained in 397 (95%) of 420 coronary segments. Coronary angiography showed the presence of coronary aneurysms in 87 segments and stenosis or occlusion in 28. The overall sensitivity and specificity of cross sectional echocardiography for correctly identifying coronary aneurysms were 95% and 99%, respectively; for correctly identifying coronary stenosis or occlusion the values were 85% and 98% for the right coronary artery, and 80% and 97% for the left anterior descending coronary artery. Agreement on the presence or absence of coronary aneurysms and obstructive lesions on echocardiograms between the two observers was 1.0 and 0.98, respectively. CONCLUSIONS: Echocardiography may provide a non-invasive means of identifying the presence and type of coronary artery disease in patients with Kawasaki disease.

Adolescent↗
PubMed2000

Modulation of laryngeal responses to superior laryngeal nerve stimulation by volitional swallowing in awake humans.

Laryngeal sensori-motor closure reflexes are important for the protection of the airway and prevent the entry of foreign substances into the trachea and lungs. The purpose of this study was to determine how such reflexes might be modulated during volitional swallowing in awake humans, when persons are at risk of entry of food or liquids into the airway. The frequency and the amplitude of laryngeal adductor responses evoked by electrical stimulation of the internal branch of the superior laryngeal nerve (ISLN) were studied during different phases of volitional swallowing. Subjects swallowed water on command while electrical stimuli were presented to the ISLN at various intervals from 500 ms to 5 s following the command. Laryngeal adductor responses to unilateral ISLN stimulation were recorded bilaterally in the thyroarytenoid muscles using hooked wire electrodes. Early ipsilateral R1 responses occurred at 17 ms, and later bilateral R2 began around 65 ms. The muscle responses to stimuli occurring during expiration without swallowing were quantified as control trials. Responses to stimulation presented before swallowing, during the swallow, within 3 s after swallowing, and between 3 and 5 s after a swallow were measured. The frequency and amplitude of three responses (ipsilateral R1 and bilateral R2) relative to the control responses were compared across the different phases relative to the occurrence of swallowing. Results demonstrated that a reduction occurred in both the frequency and amplitude of the later bilateral R2 laryngeal responses to electrical stimulation for up to 3 s after swallowing (P = 0.005). The amplitude and frequency of ipsilateral R1 laryngeal responses, however, did not show a significant main effect following the swallow (P = 0.28), although there was a significant time by measure interaction (P = 0.006) related to reduced R1 response amplitude up to 3 s after swallowing (P = 0.021). Therefore, the more rapid and shorter unilateral R1 responses continued to provide some, albeit reduced, laryngeal protective functions after swallowing, whereas the later bilateral R2 responses were suppressed both in occurrence and amplitude for up to 3 s after swallowing. The results suggest that R2 laryngeal adductor responses are suppressed following swallowing when residues may remain in the laryngeal vestibule putting persons at increased risk for the entry of foreign substances into the airway.

Adult↗
PubMed2000

Evaluation of splenic circulation after spleen-preserving distal pancreatectomy by dividing the splenic artery and vein.

BACKGROUND/AIM: In the present study, we investigated the acute and late phases of splenic circulation after spleen-preserving distal pancreatectomy (SPDP) involving the division of splenic vessels. METHODS: An acute phase of splenic circulation was evaluated by laser flow meter and the late phase was estimated by (99m)Tc-galactosyl human serum albumin spleen scintigraphy. RESULTS: Splenic blood supply, evaluated by laser flow meter immediately after SPDP, dropped to one half of the prior blood supply. However, blood supply recovered 10 days after SPDP, as estimated by (99m)Tc-galactosyl human serum albumin spleen scintigraphy. CONCLUSION: There are two variations of SPDP: SPDP without preservation of the splenic artery and vein, and SPDP with preservation of the splenic artery and vein. The disadvantage of the former is the resulting decrease in splenic blood supply. The present findings may help to make up for this disadvantage.

Humans↗
PubMed2000

Complete antithrombin deficiency in mice results in embryonic lethality.

Antithrombin is a plasma protease inhibitor that inhibits thrombin and contributes to the maintenance of blood fluidity. Using targeted gene disruption, we investigated the role of antithrombin in embryogenesis. Mating mice heterozygous for antithrombin gene (ATIII) disruption, ATIII(+/-), yielded the expected Mendelian distribution of genotypes until 14.5 gestational days (gd). However, approximately 70% of the ATIII(-/-) embryos at 15.5 gd and 100% at 16.5 gd had died and showed extensive subcutaneous hemorrhage. Histological examination of those embryos revealed extensive fibrin(ogen) deposition in the myocardium and liver, but not in the brain or lung. Furthermore, no apparent fibrin(ogen) deposition was detected in the extensive hemorrhagic region, suggesting that fibrinogen might be decreased due to consumptive coagulopathy and/or liver dysfunction. These findings suggest that antithrombin is essential for embryonic survival and that it plays an important role in regulation of blood coagulation in the myocardium and liver.

Animals↗
PubMed2000

Beneficial effects of vitamin E treatment in acute myocardial infarction.

BACKGROUND: Vitamin E (Vit E), an antioxidant, is considered to prolong survival in patients and animals after myocardial infarction. Because myocardial infarction is associated with arrhythmia and heart dysfunction, this study tested the hypothesis that early treatment with Vit E reduces mortality because of its protective effects against arrhythmia and cardiac dysfunction induced by acute myocardial infarction. METHODS: Rats were randomly divided into 4 groups: sham control, myocardial infarcted, Vit E-treated sham control, and Vit E-treated infarcted animals. Myocardial infarction was induced by ligation of the left anterior descending coronary artery. Treated animals received Vit E (25 mg/kg/d) through a gastric tube beginning 1 hour after the coronary occlusion, whereas control rats received tap water. RESULTS: Electrocardiograms (lead II) at 1, 3, 7, and 21 days after coronary occlusion in the untreated animals showed ST-segment elevation, abnormal Q waves, premature ventricular complex (PVC), and QTc prolongation. Conversely, Vit E-treated rats showed attenuated ST-segment changes, fewer abnormal Q waves, and decreased incidence of PVC after coronary occlusion. Total mortality was reduced from 38% to 16%, whereas the infarct size was decreased from 44.2% to 22.3% in infarcted rats treated with Vit E. The depression in left ventricular function as well as elevation of malondialdehyde content and conjugated diene formation in the 21-day infarcted rat hearts were prevented by Vit E treatment. CONCLUSION: These results indicate that Vit E may exert beneficial effects on the heart by reducing oxidative stress in acute myocardial infarction.

Animals↗
PubMed2000

Loss of connexin45 causes a cushion defect in early cardiogenesis.

At around embryonic day 9, the primitive heart of a mouse embryo undergoes spectacular alterations within 24 hours. We created mice harboring an nls-lacZ gene in place of connexin45, which encodes the only known gap junction protein in the primitive heart before embryonic day 9, using the Cre-loxP system. Connexin45-deficient mice died of heart failure at around embryonic day 10. They initiated heart contractions, but conduction block appeared within 24 hours after the first contractions. Their cardiac walls displayed an endocardial cushion defect, while the cardiac jelly was present. These abnormalities were caused by impairment of the epithelial-mesenchymal transformation of the cardiac endothelium. Activation of the cardiac endothelium depended on the presence of the connexin45 gap junctions since signaling through Ca(2+)/calcineurin and NF-ATc1 (originally named NF-ATc) was disrupted in the mutant hearts. These results indicate a requirement for gap junction channels during early cardiogenesis and hence implicate connexin45 in congenital heart diseases. http://www. biologists.com/Development/movies/dev4369.html

Amino Acid Sequence↗
PubMed2000

Overt congestive heart failure with mitral and aortic regurgitation due to antiphospholipid syndrome in a patient with systemic lupus erythematosus.

A 51-year-old woman with overt congestive heart failure with pleural and pericardial effusion was treated with furosemide and nifedipine, leading to improvement in her condition and a decrease in effusions. An echocardiography demonstrated mitral and aortic regurgitation with mitral valve prolapse, which caused the congestive heart failure. Since leukocytopenia and lymphocytopenia with arthralgia could be observed, serological investigations were performed. She was diagnosed as having systemic lupus erythematosus (SLE) with antiphospholipid syndrome, and started on a treatment of prednisolone and aspirin. Based on the treatment, the pleural and pericardial effusion went into complete remission, indicating that the serositis related to SLE had overlapped the heart failure. Since there was no evidence of any other diseases that could be responsible for the valvular lesions, we concluded that they were due to antiphospholipid syndrome. The administration of prednisolone had no significant effect on valvular morphology or function as demonstrated by echocardiography. When patients with valvular disease are seen, a valvulopathy related to antiphospholipid syndrome should be considered as part of the differential diagnosis.

Antiphospholipid Syndrome↗