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Biomedical subjects

K Maekawa

Publications and source records attributed to K Maekawa.

At least 19 recordsLinked to original sources
PubMed2005

Genetic polymorphisms and haplotypes of the human cardiac sodium channel alpha subunit gene (SCN5A) in Japanese and their association with arrhythmia.

Genetic variations in cardiac ion channels have been implicated not only as the causes of inherited arrhythmic syndromes, but also as genetic risk factors for some acquired arrhythmias. To elucidate the potential roles of genetic polymorphisms of the alpha subunit of the voltage-gated sodium channel type V (SCN5A) in cardiac rhythm disturbance, the entire SCN5A coding exons and their flanking introns were sequenced in 166 Japanese arrhythmic patients and 232 healthy controls. We detected 69 genetic variations, including 54 novel ones. Out of the 12 novel nonsynonymous single nucleotide polymorphisms (SNPs), p.Leu1988Arg was found at a frequency of 0.015. The other 11 SNPs were rare (0.001), with 6 found in arrhythmic patients and 5 in healthy controls. The frequency of a novel intronic SNP, c.703+130G>A, was significantly higher in the patients than in the controls, suggesting this SNP is associated with an unknown risk factor for arrhythmia. Following linkage disequilibrium analysis, the haplotype structure of SCN5A was inferred using high-frequency SNPs. The frequency of the haplotype harbouring both p.Leu1988Arg and the common SNP p.His558Arg (haplotype GG) was significantly lower in the patients than in the controls. This finding suggests that this haplotype (GG) might have been positively selected in the controls because of its protective effect against arrhythmias. This study provides fundamental information necessary to elucidate the effect of genetic variations in SCN5A on channel function and cardiac rhythm in Japanese, and probably in the Asian population.

Arrhythmias, Cardiac↗
PubMed2004

Self-reported remission, difficulty, and satisfaction with nonsurgical therapy used to treat anterior disc displacement without reduction.

OBJECTIVE: The purpose of this study was to identify the appropriate treatment element for initial anterior disc displacement without reduction subjects. STUDY DESIGN: Sixty-nine consecutive patients with temporomandibular joint disc displacement without reduction confirmed on magnetic resonance images were randomly divided into 3 experimental treatment groups. The treatment of group 1 consisted of short-term nonsteroidal anti-inflammatory drugs and self-care instructions (palliative care group); group 2, nonsteroidal anti-inflammatory drugs, self-care instructions, and occlusal appliance and mobilization therapy (physical medicine group); and group 3, no treatment (control group). Outcomes were assessed by means of a 5-item questionnaire that evaluated (1) symptom improvement, (2) difficulty of treatment, and (3) satisfaction with treatment during the 8-week observation period. RESULTS: Improvement scores in the palliative care group were significantly better than those in the physical medicine group or the no-treatment group. Satisfaction scores showed no significant difference among the 3 groups. Difficulty from treatment for the physical medicine group was significantly greater than that for other 2 groups. CONCLUSION: These data suggest that palliative care would be more appropriate as the initial therapy to treat painful anterior disc displacement without reduction.

Adult↗
PubMed2004

Dynamic imaging of pancreatic diseases by contrast enhanced coded phase inversion harmonic ultrasonography.

BACKGROUND: Coded phase inversion harmonic ultrasonography, a newly available sonographic technique, enables visualisation of slow flow in minute vessels in a real time fashion with the use of a sonographic contrast agent containing monosaccharide. Our purpose was to employ this novel technique to observe microvessels in pancreatic tumours. SUBJECTS AND METHODS: Sixty five patients with suspicious pancreatic tumours received contrast enhanced coded phase inversion harmonic ultrasonography, contrast enhanced computed tomography, and endosonography. Final diagnoses based on histological findings were pancreatic ductal carcinomas in 49 patients, inflammatory pseudotumours with chronic pancreatitis in seven, and endocrine tumours in nine. For contrast enhanced coded harmonic ultrasonography, Levovist, a contrast agent, was injected intravenously as a bolus. When the first microbubble signal appeared in the pancreas, images of the ideal scanning plane were displayed in a real time continuous fashion (vessel images). Subsequently, interval delay scanning (perfusion images) was taken to demonstrate parenchymal flow. Tumour vascularity was evaluated by using the two types of imaging. Sensitivities for depicting pancreatic tumours were compared between three examinations. RESULTS: Contrast enhanced ultrasonography demonstrated tumour vessels in 67% of pancreatic ductal carcinomas, although most were relatively hypovascular compared with the surrounding pancreatic tissue. The vascular patterns of tumours obtained by contrast enhanced ultrasonography were closely correlated with those obtained by contrast enhanced computed tomography. Values for sensitivity in depicting pancreatic tumours of 2 cm or less in size were 68% for contrast enhanced computed tomography, 95% for endosonography, and 95% for contrast enhanced ultrasonography. CONCLUSION: Contrast enhanced coded phase inversion harmonic ultrasonography successfully visualised fine vessels in pancreatic tumours and may play a pivotal role in the depiction and differential diagnosis of pancreatic tumours.

Adult↗
PubMed2003

Non-synonymous single nucleotide alterations in the microsomal epoxide hydrolase gene and their functional effects.

1. By sequencing genomic DNA from 72 established cell lines derived from Japanese individuals, we detected 25 single nucleotide alterations in the microsomal epoxide hydrolase (EPHX1) gene. Of them, five were exonic alterations resulting in amino acid alterations (77C>G, T26S; 128G>C, R43T; 337T>C, Y113H; 416A>G, H139R; 823A>G, T275A). The T26S, R43T, Y113H and H139R substitutions were found at relatively high frequencies and seemed to be polymorphic, and T26S and T275A were novel. 2. To examine the effects of these amino acid alterations on EPHX1 function, EPHX1 cDNA constructs of wild-type and five variants were transfected into COS-1 cells, and their hydrolytic activities for cis-stilbene oxide were determined in vitro. Although all of the transfectants expressed EPHX1 mRNA and protein at similar levels, the variant H139R protein was expressed at a significantly higher level (128% of the wild-type). K(m) values were not significantly different between the wild-type and variants. 3. Increase (140%) in the enzymatic activity (V(max)) of the variant H139R was accompanied by the increased EPHX1 protein level without any significant change in the intrinsic EPHX1 activity. On the other hand, the variant R43T showed increased values for V(max) and clearance (V(max)/K(m)) (around 130%) both on a microsomal protein basis and on a EPHX1 protein basis. 4. These results suggest that R43T as well as H139R increase epoxide hydrolase activity.

Amino Acid Substitution↗
PubMed2003

[Perioperative management of patient with pulmonary operation associated with interstitial pneumonia].

The prognosis of patients complicated with interstitial pneumonia (IP) who undergo pulmonary operations is very poor if acute exacerbation occurs after the operation. We have experienced 6 cases in which operations were performed on lungs complicated with IP The first patient died due to acute exacerbation, but the subsequent 5 patients had good postoperative courses due to 1) short-term administration of low-dose steroid before and after the operation, 2) avoidance of administration of high concentration of oxygen during and after the operation, and 3) administration of erythromycin before and after the operation, 4) N-acetylcysteine inhalation and administration of dl-alpha-tocopherylnicotinate before and after the operation. It is thought that careful management of such patients is needed to prevent acute exacerbation even after discharge from hospital.

Humans↗
PubMed2003

[Treatment of strategy for traumatic disruption of the thoracic aorta accompanied by multiple trauma].

Disruption of the thoracic aorta due to blunt chest trauma is often fatal and should generally be treated surgically as soon as possible. However, cases of disruption of the thoracic aorta due to blunt chest trauma are often complicated by damage to vital organs, making treatment difficult. Our policy is to treat other organs before treating the thoracic aorta in 1) cases in which fracture of the pelvic bone or bleeding from abdominal cavity organs is causing shock and 2) cases of severe cerebral contusion or intracranial hemorrhage that require emergency surgical treatment. The use of a stent for treatment of acute-stage cases should be considered prudently.

Accidents, Traffic↗
PubMed2002

Transplantation for accidental acute high-dose total body neutron- and gamma-radiation exposure.

Accidental exposure to acute high-dose total body neutron radiation is rare. We report a 35-year-old man exposed to a total body dose of 5.4 Gy neutron- and 8.5-13 Gy gamma-radiation in a radiation criticality accident. He received a blood stem cell transplant from his HLA-identical sister. There was bone marrow recovery with complete donor chimerism. Random chromatid breaks were observed in donor cells suggesting a bystander effect of neutron exposure. The subject died 82 days after the accident (75 days post transplant) from multi-organ failure.

Adult↗
PubMed2002

Signal intensity changes in T2-weighted MR image of the human trapezius muscle upon cold pressor stimulation.

OBJECTIVE: The ability to measure hemodynamics of skeletal muscle proper is one of the major goals for muscle pain researchers. The aim of the present study was to evaluate the ability of signal intensity (SI) in T2-weighted trapezius muscle magnetic resonance imaging (MRI) to detect intramuscular hemodynamic changes during cold pressor stimulation (CPS). MATERIALS AND METHODS: Fifteen healthy volunteers (mean age, 25.9+/-2.1 years) participated in this study. T2-weighted MRI was acquired using a 1.5 tesla MR unit with a body array coil. The slice level was set perpendicular to the muscle long axis at the mid-point of the horizontal portion of the right trapezius muscle. Cold pressor stimulation (4 degrees C) was applied to each subject's right foot and ankle for 2 min. The SI changes were recorded continuously for 7 min before, 2 min during, and 6 min after withdrawal of cold pressor stimulation. Six of these subjects also underwent a mock-CPS trial. RESULTS: The mean SI level in T2-weighted trapezius muscle MRI significantly increased during CPS (P<0.0001, one way repeated measure ANOVA) and returned to the baseline level after cold pressor withdrawal. No statistically significant signal changes were observed across the mock-CPS trial subjects. These findings are identical to the cold pressor-induced hemodynamic changes documented in the trapezius muscle by near-infrared spectroscopy evaluation. CONCLUSIONS: SI measurement in T2-weighted trapezius muscle MRI is sufficiently sensitive to detect intramuscular hemodynamic changes during CPS.

Adult↗
PubMed2002

Genetic variation of symbiotic fungi cultivated by the macrotermitine termite Odontotermes formosanus (Isoptera: Termitidae) in the Ryukyu Archipelago.

Fungus-growing termites have a mutualistic relationship with their cultivated fungi. To improve understanding of genetic aspects of this relationship, we examined molecular markers in the fungus-growing termite Odontotermes formosanus and its fungi Termitomyces spp. from the Ryukyu Archipelago. Based on the polymorphic band patterns obtained from arbitrarily primed polymerase chain reaction methods, we constructed cladograms for related colonies of the termites and fungi. The resulting trees indicated that the termites display little genetic variation among the colonies, while the symbiotic fungi consist of two major genetic types. In addition, molecular phylogenetic trees of the symbiotic fungi based on internal transcribed spacer and 18S rDNA suggested that these two types of fungi are different species. We also demonstrated that the fungi comprising the fruiting bodies and fungus combs are identical, and that fungus combs are probably a monoculture within a single termite colony. Our results indicate that horizontal transmission of symbiotic fungi among termite colonies occurred during the evolutionary history of this symbiosis.

Animals↗
PubMed2002

Correlation between erythrocyte aldose reductase level and human diabetic retinopathy.

AIM: To examine the relation between aldose reductase (AR) and the development and progression of diabetic retinopathy by comparing the erythrocyte AR levels with the prevalence of diabetic retinopathy in NIDDM patients. METHODS: A clinic based cross sectional study was used. 611 NIDDM patients and 73 controls were enrolled. Erythrocyte AR levels were determined by ELISA. These AR levels were then correlated with patient age, duration of diabetes, and HbA(1c) levels. AR levels were also correlated with the prevalence of diabetic retinopathy in the entire NIDDM patient group and in three subgroups formed by separating the NIDDM patients by their duration of diabetes. The prevalence of diabetic retinopathy significantly increased with increased erythrocyte AR levels in patients with duration of diabetes of less than 10 years. A similar, but non-significant correlation between the prevalence of retinopathy and increased erythrocyte AR levels was observed in patients with diabetes duration of 10-20 and >/=20 years. RESULTS: The prevalence of diabetic retinopathy increased with increased erythrocyte AR levels in NIDDM patients with a duration of diabetes of less than 10 years. CONCLUSION: It was suggested that the inhibition of AR in patients with early NIDDM might be beneficial in reducing the development of diabetic retinopathy.

Adult↗
PubMed2001

A BAC-based STS-content map spanning a 35-Mb region of human chromosome 1p35-p36.

We have devised a mapping method for rapid assembly and ordering of bacterial artificial chromosome (BAC) clones on a radiation hybrid (RH) panel, using sequence-tagged sites (STSs) and PCR. The protocol consists of two rounds of two-dimensional screening from a limited number of BACs to correspond each to an STS. In the first round, STSs are assembled in the RH bins and ordered according to PCR signals derived from 384-well microtiter plates (MTPs) in which BAC clones have been arrayed. In the second round, individual BAC clones are isolated from the MTPs to build a contig. We applied this method to a 35-Mb region spanning human chromosome 1p35-p36 and assembled 1366 BACs in 11 contigs, the longest being about 20 Mb. The working draft sequences of the human genome have been integrated into the contigs to validate the accuracy.

Chromosome Mapping↗
PubMed2001

Expression of aldose reductase and sorbitol dehydrogenase genes in Schwann cells isolated from rat: effects of high glucose and osmotic stress.

To investigate the polyol pathway activity in Schwann cells, we determined the mRNA levels of aldose reductase (AR) and sorbitol dehydrogenase (SDH) in cultured cells under hyperglycemic or hyperosmotic conditions using competitive RT-PCR technique. The expressions of AR and SDH mRNAs in Schwann cells were unaltered by high (30 mM) glucose content in the medium. On the other hand, osmotic stress elicited significant increases in AR mRNA without any effect on SDH mRNA expression. The levels of AR mRNA determined by this RT-PCR system were significantly correlated with AR activity, as well as the levels of sorbitol accumulated in Schwann cells cultured under hyperosmotic conditions. These findings suggest that in contrast to the induction of AR expression by osmotic stress, high glucose per se does not up-regulate expression of the enzymes constituting the polyol pathway in Schwann cells. The RT-PCR system developed in this study may be a useful tool in ascertaining the relative contributions of AR and SDH to the metabolic derangements leading to diabetic complications.

Aldehyde Reductase↗
PubMed2001

Biochemical and morphological changes during development of sugar cataract in Otsuka Long-Evans Tokushima fatty (OLETF) rat.

The relationship between the polyol pathway and sugar cataracts has been studied extensively using streptozotocin-induced diabetic rats and galactose fed rats as animal models for insulin-dependent diabetes mellitus (IDDM). In these models, sugar cataracts progress quickly, leading to rapid lenticular polyol accumulation in the early stages of cataract formation. In 1992, a new animal model of non-insulin-dependent diabetes mellitus (NIDDM), the Otsuka Long-Evans Tokushima Fatty (OLETF) rat, was established. In the present study, we examined both biochemical and morphological changes in the lenses of the OLETF rats to determine whether these changes reflect those associated with diabetic cataract formation and to clarify their relationship with the polyol pathway. For the biochemical analysis, we measured the enzyme activity of aldose reductase (AR) and sorbitol dehydrogenase (SDH) and the sorbitol levels using 20, 40 and 60 week old OLETF or control Long-Evans Tokushima Otsuka (LETO) rats. Enzyme activities of AR and SDH, which were lower in 20 week old OLETF rats than in LETO rats, were increased in 60 week old OLETF rats. The lenticular sorbitol level of the OLETF rats was similar to the control level at 20 weeks of age, but it was markedly increased at 40 weeks of age, and slightly decreased at 60 weeks of age compared with rats at 40 weeks but not compared with controls. Slight lens fiber swelling was observed in the anterior and/or posterior subcapsular regions of 40 week old OLETF rats, accompanying elevated sorbitol level and slightly increased SDH activity in the lens. Swelling and liquefaction of lens fibers were observed in the subcapsular and supranuclear region of 60 week old OLETF rats, as well as decreased lenticular sorbitol, and markedly increased SDH activity compared with rats at 40 weeks. AR activity was also increased causing the elevation of sorbitol in lenses of OLETF rats during the early stages of cataract formation. Despite differences in the etiology of diabetes mellitus, the strain of rat and the rate of disease progression in the OLETF rat model compared with other diabetic models, the present results support the theory that the polyol pathway via AR is a factor in the development of sugar cataracts.

Aldehyde Reductase↗
PubMed2001

Phylogeny and biogeography of wood-feeding cockroaches, genus Salganea Stål (Blaberidae: Panesthiinae), in Southeast Asia based on mitochondrial DNA sequences.

Molecular phylogenetic relationships among 25 species of the wood-feeding cockroach belonging to the genus Salganea Stål (Panesthiinae; Blaberidae) in Southeast Asia were analyzed based on the DNA sequence of the complete mitochondrial cytochrome oxidase II (COII) gene. Most basal relationships among species of Salganea are poorly resolved by both neighbor-joining and nonweighted parsimony analyses, suggesting the possibility of a hard polytomy due to a rapid and potentially simultaneous radiation early in the history of the genus. For more apical relationships, however, some interesting phylogenetic relationships were recognized. The monophyly of the two species groups, morio and foveolata, the former of which is distributed mainly in the Sunda lands (containing the Malay Peninsula, Sumatra, Java, and Borneo), whereas the latter is Sulawesi endemic, was strongly supported. Based on the inferred phylogenetic patterns and recent palaeogeographic scenario for Southeast Asia, it is suggested that a radiation of Salganea species occurred in Southeast Asia presumably in the early Tertiary, and several barriers against dispersal and gene flow, such as the formation of straits or high mountains, have arisen from the middle Tertiary.

Animals↗
PubMed2001

Intramuscular haemodynamic responses to different durations of sustained extension in normal human masseter.

Ten healthy non-smoking males (mean age 24.3+/-0.8 years) with no history of chronic muscle pain or migraine participated in this study. Intramuscular total haemoglobin (Hb), an indicator of blood volume in the illuminated area, was measured with a non-invasive, near-infrared spectroscopic device. Each participant was told to maintain maximal mouth opening to extend the masseter muscle for 30, 60 or 120 s in random order. Data were continuously recorded from the right masseter 1 min before, at set times during and for 5 min after sustained muscle extension in each trial. Each trial was separated by a 10-min interval. Heart rate (HR) and blood pressure (BP) were also recorded. The mean normalized Hb decreased during muscle extension and rebound hyperaemia was observed after it in each trial (P=0.0001). Hb returned to baseline within 60 s. The magnitude of the decremental change during extension and of the incremental change in the rebound hyperaemia was not significantly different among the three trials (P=0.9071); neither were mean normalized HR and BP. These data suggest that sustained extension of the masseter produces a reduction in total intramuscular Hb during extension and a secondary increase in Hb following a return to the resting muscle's normal length.

Adult↗
PubMed2001

Correlation of the near-infrared spectroscopy signals with signal intensity in T(2)-weighted magnetic resonance imaging of the human masseter muscle.

The purpose of this study was to compare and contrast blood volume changes transcutaneously measured using near-infrared (NIR) spectroscopy against water signal intensity changes taken from a transverse T(2)-weighted MR image of the masseter muscle in healthy human subjects before, during and after contraction. Eight healthy non-smoking males with no history of chronic muscle pain or vascular headaches participated (mean age: 23.9+/-0.6 years). The MRI data were gathered using a turbo spin echo sequence (TR: 2300 ms; TE: 90 ms; FOV: 188x300 mm; scanning time: 30 s; slice thickness: 10 mm) and the slice level was set at the mid-point between the origin and insertion of the masseter. Intramuscular haemoglobin (Hb) levels and water content of the right masseter muscle were continuously monitored for 2 min before, 30 s during and 15 min after a maximum voluntary clenching (MVC) task. Both the near-infrared and MRI data were baseline-corrected and normalized and mean levels were established and plotted. Plots of the data showed that both near-infrared-based total Hb and T(2)-weighted MRI-based signal-intensity levels clearly decreased during contraction and a clear post-contraction rebound response was evident after the contraction. The near-infrared data were found to be highly correlated with MRI-based signal-intensity data (Pearson's r=0.909, P<0.0001). In conclusion, these data provide powerful evidence that near-infrared data (total Hb), transcutaneously taken from the masseter muscle in humans, will reflect the intramuscular water signal intensity changes seen using a T(2)-weighted MRI imaging method.

Adult↗
PubMed2001

Analysis of gene expression of aldose reductase and sorbitol dehydrogenase in rat Schwann cells by competitive RT-PCR method using non-homologous DNA standards.

Aldose reductase (AR) and sorbitol dehydrogenase (SDH) are the enzymes constituting the polyol pathway, an alternate route of glucose metabolism. A wealth of experimental data has indicated the involvement of the polyol pathway in the pathogenesis of diabetic complications. However, there has been surprisingly little research on the relative abundance of SDH to AR in the tissues affected in diabetes. We therefore developed a competitive RT-PCR system to simultaneously determine the mRNA levels of these two enzymes in small amounts of samples, and studied their expression in Schwann cells isolated from adult rat sciatic nerves. Although both AR and SDH mRNA were expressed in the Schwann cells, the levels of SDH cDNA were much lower than those of AR cDNA. The induction of AR mRNA expression in the Schwann cells under hyperosmotic conditions was similarly detected by Northern blot analysis and our competitive RT-PCR method. The RT-PCR system developed in this study may be a useful tool in ascertaining the relative contributions of AR and SDH to the metabolic derangements resulting from the acceleration of polyol pathway activity in the target organ of diabetic complications.

Aldehyde Reductase↗