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Biomedical subjects

K Ikeda

Publications and source records attributed to K Ikeda.

At least 37 records · Page 2Linked to original sources
PubMed2005

Preliminary findings from tests of a microwave applicator designed to treat Barrett's oesophagus.

Barrett's oesophagus is considered to increase the risk of cancer 30-fold. Helical microwave antennas have been developed for ablative treatment of Barrett's. A microwave balloon applicator was tested in an initial animal study using adult white pigs. For treatment, a balloon filled with tissue-equivalent material encapsulated the antenna. A range of different treatment temperatures and durations was used to investigate a range of thermal ablations of the oesophageal epithelium. Eight animals were investigated, five non-survival and three with a 1-week survival period. The balloon was fitted with an array of temperature sensors, which gave an indication of the treatment in situ and allowed modifications to be performed in real time. Temperature data were recorded from all four quadrants of the balloon throughout and test sites were collected and analysed histologically. All experiments were successfully completed without perforation, serious adverse effects or death. Sites of discrete ulceration were induced in the survival tests, whereas the non-survival tests yielded little reproducible tissue modification. Results suggested that an activation temperature of approximately 55 degrees C needed to be reached during the treatment for tissue damage to be induced. Once damage had been triggered the severity was related to the mean temperature attained during the treatment period. A mean temperature of 52 degrees C or more resulted in substantial damage, whilst a mean temperature of approximately 50 degrees C resulted in the desired surface damage with sparing of subjacent tissues.

Animals↗
PubMed2005

Phenylalanine ammonia-lyase modified with polyethylene glycol: potential therapeutic agent for phenylketonuria.

Phenylketonuria (PKU) is an autosomal recessive genetic disease caused by the defects in the phenylalanine hydroxylase (PAH) gene. Individuals homozygous for defective PAH alleles show elevated levels of systemic phenylalanine and should be under strict dietary control to reduce the risk of neuronal damage associated with high levels of plasma phenylalanine. Researchers predict that plant phenylalanine ammonia-lyase (PAL), which converts phenylalanine to nontoxic t-cinnamic acid, will be an effective therapeutic enzyme for the treatment of PKU. The problems of this potential enzyme therapy have been the low stability in the circulation and the antigenicity of the plant enzyme. Recombinant PAL originated from parsley (Petroselinum crispum) chemically conjugated with activated PEG2 [2,4-bis(O-methoxypolyethyleneglycol)-6-chloro-s-triazine] showed greatly enhanced stability in the circulation and was effective in reducing the plasma concentration of phenylalanine in the circulation of mice. PEG-PAL conjugate will be an effective therapeutic enzyme for the treatment of PKU.

Animals↗
PubMed2005

Participation of the nonreducing terminal beta-galactosyl residues of the neutral N-linked carbohydrate chains of porcine zona pellucida glycoproteins in sperm-egg binding.

The zona pellucida (ZP) surrounding the mammalian oocyte is composed of three glycoprotein components (ZPA, ZPB, and ZPC). Mammalian sperm bind to carbohydrate chains of a ZP glycoprotein in the initial phase of fertilization. Sperm-ligand carbohydrate chains have been characterized in mouse, cow, and pig. In pigs, triantennary/tetraantennary neutral complex-type chains from ZPB/ZPC mixture possess stronger sperm-binding activity than those of biantennary chains (Kudo et al., 1998: Eur J Biochem 252:492-499). Most of these oligosaccharides have beta-galactosyl residues at the nonreducing ends. This study used two in vitro competition assays to investigate the participation of the nonreducing terminal beta-galactosyl residues of the ligand active chains in porcine sperm binding. The removal of the nonreducing terminal beta-galactosyl residues from either the ligand active carbohydrate chains or endo-beta-galactosidase-digested glycoproteins significantly reduced their inhibition of sperm-egg binding, indicating that the beta-galactosyl residues at the nonreducing ends are involved in porcine sperm-egg binding. A correlation between the sperm-binding activity and in vitro fertilization rate is also presented.

Animals↗
PubMed2005

Dietary habits, plasma polyunsaturated fatty acids and selected coronary disease risk factors in Tanzania.

OBJECTIVES: To compare dietary habits and percent compositions of omega (omega)-3 fatty acid (FA) in plasma phospholipids and to examine if there is any association between fish intake and selected coronary disease risk (CHD) factors in this population. DESIGN: Cross sectional population study. SETTING: Three areas in Tanzania: urban Dar es Salaam (D), rural Handeni (H) and pastoralist population of Maasai in Moduli (Mo). SUBJECTS: One hundred and five participants (Dar 36, Handeni 37 and Monduli 32) aged 47-57 years. MAIN OUTCOME MEASURES: Fatty acids composition in plasma phospholipids. RESULTS: The frequency of intake of fish, meat, coconut milk and fruits was higher in Dar than in Handeni or Monduli (all p< 0.0001). The Maasai from Monduli had the highest percentage consumption of milk in a week (p<0.0001) and lowest intake of fish (p<0.0001). Participants from Handeni had the highest prevalence of consumption of green vegetables (p<0.0001). Percent compositions of arachidonic acid (AA; C20: 4omega-6) and docosahexaenoic acid (DHA; C22: 6omega-3) in plasma phospholipids were the lowest in Monduli (p<0.0001). Selected coronary disease risk factors were higher in the urban area Dar. The frequency of intake of fish per week correlated negatively with total cholesterol (TC) and LDL-C and HBA1c percent but not with blood pressure. The percent composition of omega-3 FA in plasma phospholipids was positively correlated with the frequency of intake of fish a week. CONCLUSION: Our results indicate that, there are significant differences in dietary patterns among the three study areas, and that the intake of fish is inversely associated with selected risk factors for coronary heart disease.

Cholesterol↗
PubMed2005

[Autologous fibrin sealant preparing system in coronary artery bypass grafting].

Autologous fibrin sealant (AFS) which is not based on the conventional method of co-administering fibrinogen, thrombin and aprotinin was prepared by Vivostat system, and was used in coronary artery bypass grafting (CABG). The purpose of this study was to investigate the safety and efficacy of the AFS prepared by the Vivostat system. In 6 of 68 cases of CABG, normal AFS was not prepared due to device failures. AFS was prepared and sprayed in 62 cases. There were the total of 230 anastomosis sprayed AFS and the bleeding could not seen in 225 anastomosis. Surgical hemostatic procedures (4 cases) were or other sealant usage (1 case) was performed 5 bleeding anastomosis sites. The rate of hemostasis at the anastomosis using AFS was 97.8%. This study was conducted in patients undergoing CABG. In this group of patients, a number of commercial available fibrin sealant products are routinely used. The usefulness of Vivostat as medical device to prepare and administer AFS was confirmed in this study.

Adult↗
PubMed2005

[Stanford type A aortic dissection with occlusion of the brachiocephalic artery; report of a case].

A 73-year-old female was referred to our hospital because of pain in the right upper extremity, left hemiparesis and syncope. Computed tomography (CT) of the head showed no active lesion, but chest CT showed Stanford type A aortic dissection with occlusion of the brachiocephalic artery. Carotid ultrasonography showed occlusion of the right common carotid artery. Emergent graft replacement of the ascending aorta and aortic arch was performed. The right common carotid artery was opened but no thrombus was found. In order to restore and maintain the cerebral circulation, the right carotid artery was cannulated. Postoperative head CT showed a small cerebral infarction of the right parietal lobe. Syncope did not recur and her hemiparesis was treated by rehabilitation. Cannulation of the carotid artery is useful for cases with occlusion of the brachiocephalic artery.

Aged↗
PubMed2004

The role of climate variability in the inter-annual variation of terrestrial net primary production (NPP).

Eleven years data set of global net primary production (NPP) and long-term climatic and land use data were used to explore the patterns of inter-annual variability of terrestrial NPP in relation to potential causal factors. Global anomalies in temperature, precipitation and cloud cover were found to significantly contribute in different ways and magnitudes to the variability of NPP of global ecosystems particularly forests and grasslands. El Niño/La Niña events represented an important factor affecting forests, woodlands and grasslands while deforestation was found to largely contribute to the NPP variability of tropical forests. Regionally, NPP variability is related to variation of precipitation in the tropics but is related to both variation and annual mean of temperature and cloud cover in the mid-northern latitudes. We hypothesized that the increase in variability of potential causal factor(s) will provoke more declines of NPP in the tropics but will yield more pulses or at least maintain a mean NPP in the mid-northern latitudes.

Carbon Dioxide↗
PubMed2004

Equilateral-triangular shape in 14C.

An equilateral-triangular shape of three alpha clusters surrounded by excess neutrons is suggested for 14C, based on the molecular-orbit model. It is found that the attractive interaction between an excess neutron and an alpha particle stabilizes the K(pi)=0(+) and 3(-) rotational bands, which demonstrates an equilateral-triangular symmetry. This K(pi)=3(-) band at 3 MeV below the 10Be+alpha threshold energy corresponds to the experimentally observed band built on top of the second 3(-) state. A positive-parity rotational band (0(+), 2(+), 4(+)) arises similarly. These two bands suggest a molecular 3-alpha structure stabilized by the excess neutrons and can be viewed as a realization of the alpha crystallization in the dilute nuclear medium.

Journal Article↗
PubMed2004

Frontotemporal dementia with Pick-type histology associated with Q336R mutation in the tau gene.

In this report, we describe the clinical and neuropathological features of a case of familial frontotemporal dementia (FTD), with onset at 58 years of age and disease duration of 10 years, associated with a novel mutation, Q336R, in the tau gene (tau). In vitro studies concerning the properties of tau proteins bearing this mutation, with respect to microtubule assembly and tau filament aggregation, are reported. Clinically, the patient showed alterations in memory, language and executive functions and marked behavioural change consistent with FTD, although the extent of memory impairment was more than is characteristic of FTD. At autopsy, there was degeneration of the frontal and temporal lobes associated with the presence of hyperphosphorylated tau proteins in swollen (Pick) cells and intraneuronal inclusions (Pick bodies). By immunohistochemistry, the Pick bodies contained both 3-repeat and 4-repeat tau proteins although, because no fresh tissues were available for analysis, the exact isoform composition of the aggregated tau proteins could not be determined. Neurons within frontal cortex contained neurofibrillary tangle-like structures, comprising both straight and twisted tubules, or Pick bodies in which the filaments were short and randomly orientated. In vitro, and in common with other tau missense mutations, Q336R caused an increase in tau fibrillogenesis. However, in contrast to most other tau missense mutations, Q336R increased, not decreased, the ability of mutant tau to promote microtubule assembly. Nonetheless, this latter functional change may likewise be detrimental to neuronal function by inducing a compensatory phosphorylation that may yield increased intracellular hyperphosphorylated tau species that are also liable to fibrillize. We believe the mutation is indeed pathogenic and disease causing and not simply a coincidental rare and benign polymorphism. Since this mutation is segregating with the FTD clinical and neuropathological phenotype, it has not been found in unaffected individuals and it has novel functional properties in vitro which are likely to be detrimental to neuronal function in vivo.

Aged↗
PubMed2004

High sensitivity search for nu;e's from the sun and other sources at KamLAND.

Data corresponding to a KamLAND detector exposure of 0.28 kton yr has been used to search for nu;(e)'s in the energy range 8.3<E(nu;(e))<14.8 MeV. No candidates were found for an expected background of 1.1+/-0.4 events. This result can be used to obtain a limit on nu;(e) fluxes of any origin. Assuming that all nu;(e) flux has its origin in the Sun and has the characteristic 8B solar nu(e) energy spectrum, we obtain an upper limit of 3.7 x 10(2) cm(-2) s(-1) (90% C.L.) on the nu;(e) flux. We interpret this limit, corresponding to 2.8 x 10(-4) of the standard solar model 8B nu(e) flux, in the framework of spin-flavor precession and neutrino decay models.

Journal Article↗
PubMed2004

Global pollution monitoring of butyltin compounds using skipjack tuna as a bioindicator.

Butyltin compounds (BTs) including mono- (MBT), di- (DBT), tri-butyltin (TBT) and total tin (sigmaSn), were determined in the liver of skipjack tuna (Katsuwonus pelamis) collected from Asian offshore waters (off-Japan, the Japan Sea, off-Taiwan, the East China Sea, the South China Sea, off-Philippines, off-Indonesia, the Bay of Bengal), off-Seychelles, off-Brazil and open seas (the North Pacific). BTs were detected in all the skipjack tuna collected, suggesting widespread contamination of BTs even in offshore waters and open seas on a global scale. Considering specific accumulation, Sex-, body length- differences and migration of skipjack tuna did not seem to affect BT concentrations, indicating rapid reflection of the pollution levels in seawater where and when they were collected. Skipjack tuna is a suitable bioindicator for monitoring the global distribution of BTs in offshore waters and open seas. High concentrations of BTs were observed in skipjack tuna from offshore waters around Japan, a highly developed and industrialized region (up to 400 ng/g wet weight). Moreover skipjack tuna collected from offshore waters around Asian developing countries also revealed the levels comparable to those in Japan (up to 270 ng/g wet weight) which may be due to the recent improvement in economic status in Asian developing countries. High percentages (almost 90%) of BTs in total tin (sigmaSn: sum of inorganic tin+organic tin) were found in the liver of skipjack tuna from offshore waters around Asian developing countries. This finding suggests that the anthropogenic BTs represent the major source of Sn accumulation in skipjack tuna from these regions.

Animals↗
PubMed2004

Molecular characterization of bipolar disorder by comparing gene expression profiles of postmortem brains of major mental disorders.

We performed the oligonucleotide microarray analysis in bipolar disorder, major depression, schizophrenia, and control subjects using postmortem prefrontal cortices provided by the Stanley Foundation Brain Collection. By comparing the gene expression profiles of similar but distinctive mental disorders, we explored the uniqueness of bipolar disorder and its similarity to other mental disorders at the molecular level. Notably, most of the altered gene expressions in each disease were not shared by one another, suggesting the molecular distinctiveness of these mental disorders. We found a tendency of downregulation of the genes encoding receptor, channels or transporters, and upregulation of the genes encoding stress response proteins or molecular chaperons in bipolar disorder. Altered expressions in bipolar disorder shared by other mental disorders mainly consisted of upregulation of the genes encoding proteins for transcription or translation. The genes identified in this study would be useful for the understanding of the pathophysiology of bipolar disorder, as well as the common pathophysiological background in major mental disorders at the molecular level. In addition, we found the altered expression of LIM and HSPF1 both in the brains and lymphoblastoid cells in bipolar disorder. These genes may have pathophysiological importance and would be novel candidate genes for bipolar disorder.

Adaptor Proteins, Signal Transducing↗
PubMed2004

Differential cytokine induction by two types of Porphyromonas gingivalis.

The presence of Porphyromonas gingivalis with type II fimA is strongly associated with adult periodontitis. However, the importance of specific fimA types in the immune response is unknown. Two types of P. gingivalis (type I and type II) and Actinomyces naeslundii were assessed for their degree of cytokine induction in the macrophage-like human cell line U937. Real-time reverse transcriptase polymerase chain reaction was used to determine mRNA expression of 12 cytokines. Significant levels of interleukin (IL)-8 induction and a similar cytokine expression pattern were observed at 6 h postinfection for all three bacterial strains. However, type II P. gingivalis infection showed statistically higher levels of IL-1beta, IL-8, IL-12 and tumor necrosis factor-alpha mRNA induction than those of control at 24 h postinfection, whereas type I P. gingivalis and A. naeslundii showed no significant induction of these cytokines. These data suggest that compared with A. naeslundii and type I P. gingivalis, type II P. gingivalis prolongs the cytokine response. Although other factors may also be involved, the sustained cytokine response induced by type II P. gingivalis may play an important role in enhanced periodontal tissue inflammation and destruction.

Actinomyces↗