Biomedical subjects

K Tsuchiya

Publications and source records attributed to K Tsuchiya.

At least 145 records · Page 8Linked to original sources

PubMed2000

Pathologic examination of renal cell cancer by means of step-sectioning.

BACKGROUND: Because incidental detection of small renal cell cancers (RCC) has recently become increasingly common, nephron-sparing surgery for these cases has been more widely performed. Renal cell cancer was investigated by means of step-sectioning in order to determine which cases were suitable for nephron-sparing surgery and how it should be performed. METHODS: Pathology specimens obtained from 90 cases of radical nephrectomy were examined in 5 mm sections. We excluded large and invasive tumors from the present study. Particular attention was given to satellite tumor nodules (STN), pseudocapsules of the main tumor and vascular invasion. RESULTS: Satellite tumor nodules of cancer (STN-Ca) were found in seven of 90 cases (7.8%). Tumor size and grade was not correlated with the existence of STN-Ca. The distance between the main tumor and STN-Ca varied. with the pathology of the STN-Ca mostly resembling that of the main tumor. Pseudocapsules of the main tumor were incomplete in 53 cases (58.9%), but extracapsular invasion of more than 1 mm was not seen in tumors less than 50 mm in diameter. Through step-sectioning, a further six cases with microscopic vascular invasion were found. Vascular invasion within the main tumor was confirmed in 16 of 17 cases (94.1%) and within normal renal tissue in only one case. CONCLUSIONS: The incidence of existing STN-Ca was not high (7.8%) in the present study, we had not any characteristics in the cases with STN-Ca. As STN-Ca were rarely near the main tumor, we could not expect to resect STN-Ca with main tumor, resection to more than 1 mm outside the pseudocapsule was needed for complete resection of main tumor less than 50 mm in diameter. Normal renal tissue between the tumor and pelvis is a requirement for selecting appropriate cases in nephron-sparing surgery, but we could not remove the risk of leaving STN-Ca completely.

Adenoma↗

PubMed2000

Multiple sclerosis with very late onset: a report of a case with onset at age 82 years and review of the literature.

This is a report of a patient with late-onset multiple sclerosis at age 82 years. The lesion involved was located on the spinal cord. Multiple sclerosis mainly affects young adults, making late onset of multiple sclerosis a rarity, particularly for cases after age 80 years. Common characteristics of late-onset multiple sclerosis reported in other publications are predominant involvement of the spinal cord and a progressively worsening course with a serious prognosis. In this case, magnetic resonance imaging revealed a large area of high signal intensity in the cervical and upper thoracic spinal cord on T2-weighted images. An increased immunoglobulin G level in cerebrospinal fluid also played a diagnostic role in ruling out cervical spondylotic myelopathy. Spontaneous improvement occurred 2 months after the onset. Unlike other patient described in the literature, the clinical course of this man was not as bleak.

Age of Onset↗

PubMed2000

Long-term regulation of catecholamine formation by ouabain in cultured bovine adrenal chromaffin cells.

The long-term effects of ouabain, an inhibitor of Na+/K+ -ATPase, on catecholamine formation in cultured bovine adrenal chromaffin cells were examined. The increase in [14C]catecholamine formation from [14C]tyrosine induced by ouabain was dependent on incubation time, and its maximal effect was observed after incubation for 8 h. The stimulatory effect of ouabain was concentration dependent (10-300 nM), causing maximal stimulation at 300 nM. The formation of [14C]catecholamines induced by ouabain was not increased by incubation with [14C]DOPA instead of [14C]tyrosine. Ouabain-induced [14C]catecholamine formation was influenced by decreases in extracellular Ca2+ concentration, but not by the presence of cycloheximide or actinomycin D. These results suggested that ouabain stimulates continuous activation of hydroxylation of tyrosine through a Ca2+ -dependent mechanism in cultured bovine adrenal chromaffin cells.

Animals↗

PubMed2000

Appearance of frontal midline theta activity in patients with generalized anxiety disorder.

The appearance of frontal midline theta activity (Fmθ), recognized as distinct EEG theta rhythm in the frontal midline area during performance of a mental task, reflects feelings of relief from anxiety in humans. In the present study, EEGs were recorded, and the Hamilton Rating Scale for Anxiety and the state anxiety scale of Spielberger's State-Trait Anxiety Inventory were evaluated once a week in 28 patients with generalized anxiety disorder. The Taylor Manifest Anxiety Scale and the trait anxiety scale of Spielberger's State-Trait Anxiety Inventory were used to assess anxiety before and after the tests. The present results suggest that the appearance of Fmθ might be closely related to an improvement in the anxiety symptoms associated with generalized anxiety disorder.

Adolescent↗

PubMed2000

Effects of photoperiod and ambient temperature on the gonadotropin-releasing hormone neuronal system in the gray hamster, Tscherskia triton.

In seasonal breeders like the hamster, gonadal function depends on the photoperiod. The present study examined the effects of different photoperiods and ambient temperatures on the gonadotropin-releasing hormone (GnRH) neuronal system in male gray hamsters, Tscherskia triton. Hamsters were kept from birth under a long-day (LD: 16 h light and 8 h dark) photoperiod and at 23 degrees C until the experiment began. The animals were then kept for 30 days under different photoperiods and ambient temperatures. After autopsy, immunocytochemical and semiquantitative reverse transcription-polymerase chain reaction analyses were performed on the hamster forebrain. Exposure to a short-day (SD: 8 h light and 16 h dark) photoperiod at 23 degrees C induced a functional decline in the GnRH neuronal system (increased neuron number and immunoreactivity, and reduced cell size). LD with low ambient temperature (7 degrees C) did not influence the GnRH neuronal system. In contrast, SD with low ambient temperature enhanced the SD-induced functional decline in GnRH neurons. Changes in immunoreactivity of GnRH fibers in the median eminence, their release site, were also similar to those in neuronal perikarya. Significant differences in GnRH gene expression were detected in the SD only group and the SD with low ambient temperature group. However, no differences were detected between the two groups. These findings suggest that low ambient temperature enhanced the SD-induced decline in GnRH release from nerve terminals, but was not a crucial factor in the synthesis of this decapeptide.

Animals↗

PubMed2000

Preliminary study of continuous glucose monitoring with a microdialysis technique and a null method--a numerical analysis.

Monitoring of the subcutaneous tissue glucose concentration is an attractive method for continuous monitoring of the glucose concentration in diabetic patients. Several researchers have studied this, but no satisfactory method has been developed. We have proposed a new method, which can measure the glucose concentration of subcutaneous tissue continuously, even as the efficiency of membrane perfusion and sensor performance decline. Two reference solutions were prepared with concentrations higher and lower than the objective solution. They were perfused alternately for different ratios of perfusion times. The glucose concentration, after perfusing microdialysis, was detected and the trend of changes in the concentration was used to control the ratio of the two perfusion solutions. When the trend was a unity, the glucose concentration was calculated from the ratio of the two perfusion solutions. The numerical study was performed with a compartment model and a basic control theory. In simulation, the 90% response time to step change was approximately 7 min, which is fast enough when compared with the fluctuation of glucose in the electrolyte. This result suggested that this new system might be useful for continuous monitoring of the glucose concentration in subcutaneous tissue.

Biosensing Techniques↗

PubMed2000

Effect of endothelin-1 (1-31) on human mesangial cell proliferation.

It was previously found that human chymase cleaves big endothelins (ETs) at the Tyr31-Gly32 bond and produces 31-amino acid ETs (1-31). In the present study, human plasma concentrations of ET-1 (1-31) and ET-1 were examined and the effect of synthetic ET-1 (1-31) on the proliferation of cultured human mesangial cells (HMCs) was investigated. The proliferative effect of ET-1 (1-31) was evaluated from the [3H]-thymidine uptake. The activity of extracellular signal-regulated kinase (ERK) and DNA binding activity of activator protein-1 were determined by using an in-gel kinase assay and gel mobility shift assay, respectively. Immunoreactive ET-1 (1-31) was detectable in plasma, but the level was slightly lower than that of ET-1. ET-1 (1-31) increased [3H]-thymidine incorporation in HMCs to a degree similar to that induced by ET-1. ET-1 (1-31) also activated ERK1/2. Inhibition of protein kinase C and ERK kinase caused a reduction of ET-1 (1-31)-induced ERK1/2 activation. The ERK1/2 activation was followed by an increase in transcription factor activator protein-1 DNA binding activity. These findings suggest that ET-1 (1-31) is a bioactive peptide in humans and ET-1 (1-31) itself stimulates HMC proliferation.

Adult↗

PubMed2000

Molecular phylogeny of East Asian moles inferred from the sequence variation of the mitochondrial cytochrome b gene.

Taxonomic analysis has previously revealed that the species of moles that inhabit Japan are characterized by exceptional species richness and a high level of endemism. Here, we focused on the evolutionary history of the four Japanese mole species of the genera Euroscapter and Mogera, examining mitochondrial cytochrome b (cyt b) gene sequences and comparing them with those of continental Mogera wogura (Korean and Russian populations), M. insularis from Taiwan, and Talpa europaea and T. altaica from the western and central Eurasian continent, respectively. Our data support the idea that in a radiation center somewhere on the Eurasian continent, a parental stock evolved to modern mole-like morph and radiated several times intermittently during the course of the evolution, spreading its branches to other peripheral geographic domains at each stage of the radiation. Under this hypothesis, the four lineages of Japanese mole species, E. mizura, M. tokudae, M. imaizumii, and M. wogura, could be explained to have immigrated to Japan in this order. Mogera wogura and M. imaizumii showed substantial amounts of geographic variation and somewhat complicated distributions of the cyt b gene types. These intraspecific variations are likely to be associated with the expansion processes of moles in the Japanese Islands during the Pleistocene glacial ages.

Animals↗

PubMed2000

Evolutionary trends of the mitochondrial lineage differentiation in species of genera Martes and Mustela.

We compared partial sequences (402 bp) of the mitochondrial cytochrome b gene in 68 individuals of martens (Martes), weasels (Mustela) and their relatives from the Northern Hemisphere to identify the modes of geographic differentiation in each species. We then compared complete sequences (1140 bp) of the gene in 17 species of the family Mustelidae to know the spatial and temporal modes of speciation, constructing linearized trees with transversional substitutions for deeper lineage divergences and with transversions and transitions for younger lineages. Our data suggested that these lineages of Martes and Mustela differentiated in a stepwise fashion with five radiation stages from the generic divergences (stage I) to the intraspecific divergences (stage V), during the last 10 or 20 million years as the fossil evidence suggests. In the lineage of Martes, the first offshoots are of Martes flavigula, M. pennanti, and Gulo gulo (stage II), the second is M. foina (stage III), and the third are M. americana, M. martes, M. melampus, and M. zibellina (stage IV). The divergence of the lineages of Mustela is likely to have taken place concurrently with the radiations of the Martes. These divergence processes are attributable in part to the geographic allocation along the two continents, North America and Eurasia, as well as among peripheral insular domains, such as Taiwan and the Japanese Islands. In addition, the Eurasian continent itself was shown to have been involved in the species diversification in the martens and weasels.

Animals↗

PubMed2000

[Coronary revascularization in a patient with bilateral internal carotid artery stenosis and aneurysm of brachiocephalic artery: a case report].

A 67-year-old man with a twenty-year history of effort angina was referred to our hospital. He underwent successful PTCA for the right coronary artery and diagonal branch. However, his angina recurred three months after PTCA due to restenosis and he was recommended to undergo CABG. Because he had concomitant bilateral internal carotid artery stenosis and aneurysm of the brachiocephalic artery, we chose two-staged operation strategy to avoid cerebrovascular complication during CABG. First, he underwent bilateral carotid endarterectomy (CEA), and then he underwent concomitant CABG and grafting of brachiocephalic artery 12 days after CEA. After these operations he recovered uneventfully without neurological complication.

Aged↗

PubMed2000

[Natriuresis and blood pressure in patients with chronic renal failure following L-arginine infusion].

Nitric oxide (NO) is known to be generated from L-arginine and may regulate glomerular filtration, tubular sodium reabsorption, and renin secretion. Impairment of renal function might influence NO production secondary to endothelial dysfunction, decreased NO synthesis and increased activity of arginine analogues inhibiting NO synthase. In this study, we evaluated the effect of L-arginine on the blood pressure and urinary sodium excretion in patients with chronic renal failure. A 300-ml dose of 10% L-arginine solution was administered intravenously over 30 min and blood pressure was monitored every 10 min under basal conditions and for 120 min after infusion. The patients were divided into two groups based on the reduction in mean blood pressure (dMBP) following infusion, namely non-responders (dMBP < 10 mmHg) and responders (dMBP > 10 mmHg). Urine and blood samples were collected to determine electrolytes, urinary NO2 + NO3 by the Griess method, urinary cGMP, plasma renin activity (PRA), and the plasma aldosterone concentration (PAC). L-arginine significantly decreased MBP in 8 patients and caused no significant change in 10 patients. Urinary sodium excretion and the NO2 + NO3 level were significantly increased following L-arginine infusion and the increment of fractional excretion of sodium was higher in responders. However, there were no significant changes in PRA, PAC, and cGMP. Our findings suggest that a vasodilator effect of NO induced by L-arginine loading may, at least in part, be associated with increased renal sodium excretion in patients with chronic renal failure.

Adult↗

PubMed2000

MR digital subtraction angiography of cerebral arteriovenous malformations.

BACKGROUND AND PURPOSE: Although phase-contrast MR angiography provides some information regarding hemodynamics of cerebral arteriovenous malformations (AVMs), most conventional MR angiographic techniques have not been helpful in this respect. We attempted to determine the value of MR digital subtraction angiography (DSA) in assessing AVM hemodynamics. METHODS: We developed an MR DSA technique by combining rapid thick-section T1-weighted imaging with a bolus injection of contrast material. The temporal resolution was 0.56 to 0.61 seconds per scan. MR DSA images obtained from 14 patients with AVMs were reviewed. Anatomic depiction of each component of the AVM was rated using a four-point grading scale (excellent = 3, good = 2, fair = 1, poor = 0) to compare conventional vs MR angiograms. RESULTS: We were able to obtain serial images in which passage of contrast material was evident within the AVM, although the sequence we used allowed images to be obtained in only one projection. The average score for feeders, nidi, and drainers was 1.6, 2.4, and 2.3, respectively, with an overall average of 2.1. CONCLUSION: The spatial resolution of our technique may fall below the level needed for identification of small vascular components of an AVM. Additionally, the limited slab may restrict application of the technique to assessment of large or very small AVMs. MR DSA, however, can show the hemodynamics of AVMs and may serve as a supplement to conventional MR imaging in the diagnosis of cerebral AVMs.

Adolescent↗

PubMed2000

[MVP for MR associated with extensive calcification of the mitral valve annulus].

We experienced two surgical cases of MR associated with extensive calcification of the mitral valve annulus. For two cases we performed MVP which consisted of valve repair and annular remodeling. Annular remodeling was performed only on the annulus without calcification using 3 mm Gore-tex graft, because calcified annulus did not contribute to annular dilatation and would not dilate in the future. Both patients recovered uneventfully. Postoperative echocardiography revealed no MR in both cases.

Aged↗

PubMed2000

[Functional restoration of tumor suppressor p53 alters susceptibility of glioblastoma cells to irradiation--analysis using a cell line containing a temperature-sensitive mutant].

To examine the functional role of tumor suppressor p53 in radiosensitivity of glioblastoma multiforme cells, I analyzed radiosensitivity of three glioblastoma cell lines with different p53 statuses: LN444 (wild-type p53), U251MG (mutant R273Q), and LN382 (mutant V197L). The mutant V197L is a temperature-sensitive (ts) mutant, of which transcriptional activity is almost normal at 34 degrees C but lost at 37 degrees C in yeast p53 functional assay. Transcriptional activity V197L p53 on mdm2, p21/WAF1, and Bax promoters determined by a luciferase assay increased respectively by 6.5, 33.4, and 4.9 folds at 34 degrees C, compared to those at 37 degrees C. Semiquantitative multiplex RT-PCR showed a slight increase of Bax mRNA expression at 34 degrees C but a marked increase of p21 mRNA expression, indicating that this ts mutant restored transcriptional activity predominantly on p21 promoter at the permissible temperature. Corresponding to the p21 transactivation, growth of LN382 cells was completely arrested without apoptosis when cultured at 34 degrees C but this arrest was reversed at 37 degrees C with a delay time subsequently to 24 or 48 h of culture at 34 degrees C. Clonogenic assay showed that dose-dependent radiosensitivity of LN382 cells to gamma-irradiation was markedly enhanced at 34 degrees C compared to that at 37 degrees C, whereas those of LN444 and U251MG were not changed between 34 and 37 degrees C. This sensitization was not attributable to apoptosis induction, since no DNA ladder formation nor sub-G1/0 phase cells were observed. Instead, cell cycle analysis demonstrated G1 and G2M arrest of the LN382 cells cultured at 34 degrees C after irradiation. In agreement to this, an increase of p21 expression was further enhanced by irradiation. In conclusion, these findings altogether suggest that p21 expression by restoration of p53 function can increase the radiosensitivity of glioblastoma cells by arresting the cells at G1 and G2M phases.

Cell Cycle↗

PubMed2000

[Immunohistochemical analysis of the normal and cystic kidney using antibody against polycystin 2].

A second gene responsible for polycystic kidney disease(PKD) has been identified recently, and an antisera(YCC2) against this gene's product, polycystin 2, has been generated. In the present study, we investigated the normal distribution of polycystin 2 in human adult kidneys and analyzed the expression of polycystin 2 in the cystic tubules of kidneys from patients with PKD and acquired cystic disease of the kidney(ACDK). The expression of polycystin 2 in normal regions of resected human kidneys, 4 cases of autosomal dominant polycystic kidney disease(ADPKD) and 4 cases of ACDK was examined by immunohistochemically staining the specimens with a polyclonal antibody specific to the C-terminal region of polycystin 2. This region is specific to polycystin 2 and does not crossreact with polycystin 1. In normal kidneys, prominent expression of polycystin 2 was observed in the distal tubules. A faint level of expression was detected in the proximal tubules, and the glomerulus and vessels were almost negative for expression. In the cystic kidneys of ADPKD patients, 68.7% of the cystic tubules stained positively for YCC2, although partial staining was seen in 41.2% of the positive cystic tubules. Although the genetic background of the samples is unknown, the co-existence of positive and negative cysts suggest that a "two-hit" hypothesis is feasible and that the mutations are likely to be missense or in frame changes. In ACDK cysts, YCC2-positive staining was prominent in small cysts (less than 0.5 mm in diameter), which were also positive for DBA, a marker for distal tubules. In contrast, larger cysts of more than 0.5 mm in diameter which stained positive for a proximal tubule marker, Lotus T, tended to be less positively stained for YCC2. Overall, 94.5% of the cysts stained positive for YCC2, which is a much higher rate than that of PKD cysts. These results suggest that ACDK cysts may be generated by a different mechanism from that of PKD cysts.

Humans↗

PubMed2000

[The effects of ACE inhibitor treatment and ACE gene polymorphism on erythropoiesis in chronic hemodialysis patients].

Aggravation of anemia in chronic renal failure patients by angiotensin-converting enzyme inhibitors (ACEIs) has been attributed to the inhibition of angiotensin II which facilitates erythropoietin(Epo) production. This study was aimed at evaluating whether ACEIs aggravate anemia in maintenance hemodialysis patients and to investigate the influence of ACE gene polymorphism on erythropoiesis in these patients. Ninety-one hemodialysis patients were divided into 2 groups, based on whether or not they were administered ACEIs, into the ACEI group(n = 24) and the non-ACEI group(n = 67), and comparisons were made of the doses of recombinant human Epo(rHuEpo) administered, the hematocrit(Hct) and the plasma Epo concentrations. Among the patients in the non-ACEI group, only 17 did not receive rHuEpo, while all of the patients in the ACEI group received rHuEpo. The average dose of rHuEpo was 102.7 +/- 45.4 IU/kg/week in the ACEI group and 57.8 +/- 55 IU/kg/week in the non-ACEI group and the difference between the two groups was statistically significant. A statistically significant difference in the Hct was also observed between the two groups: the mean Hct in the ACEI group was 28.7 +/- 2.9% while that in the non-ACEI group was 31.1 +/- 3.7%. The plasma Epo concentrations were significantly lower in the ACEI group than in the non-ACEI group. No significant differences in the rHuEpo dose and Hct were observed between the three ACE genotype classes in either the ACEI or the non-ACEI group, however, there was a significant difference among the three genotypes in the non-ACEI group in regard to the plasma Epo concentrations; patients with the DD genotype had higher concentrations than those with the DI or II genotypes. These data suggest that anemia in maintenance hemodialysis patients is worsened by ACEIs as a result of the suppression of Epo production. Although it has been suggested that the endogenous Epo concentrations in maintenance hemodialysis patients are associated with ACE gene polymorphism, no significant influence of the ACE genotype on the rHuEpo dose or Hct was evident. Therefore, it is possible that exacerbation of anemia by ACEIs in the patients receiving rHuEpo is a result of an inhibited bone marrow response to Epo.

Adult↗

PubMed1999

Synthesis and histone deacetylase inhibitory activity of new benzamide derivatives.

Newly synthesized benzamide derivatives were evaluated for their inhibitory activity against histone deacetylase. The structure of these derivatives was unrelated to the known inhibitors, and IC(50) values of the active compounds were in the range of 2-50 microM. Structure-activity relationship on the benzanilide moiety showed that the 2'-substituent, an amino or hydroxy group, was indispensable for inhibitory activity. Although the electronic influence of the substituent in the anilide moiety showed only a small effect on inhibitory activity, the steric factor in the anilide moiety, especially at positions 3'and 4', played an important role in interaction with the enzyme. Among these benzamide derivatives, MS-275 (1), which showed significant antitumor activity in vivo, has been selected for further investigation.

Antineoplastic Agents↗

PubMed1999

Synthesis and antimalarial activity of cyclic peroxides, 1,2,4,5, 7-pentoxocanes and 1,2,4,5-tetroxanes.

A variety of 1,2,4,5,7-pentoxocane and 1,2,4,5-tetroxane derivatives were prepared as potential peroxide antimalarial agents. In both series of cyclic peroxides, the steric and electronic effects of the substituents attached to the peroxide ring exert a remarkable influence on the antimalarial activity. For some cyclic peroxides, which were found to be highly effective in vitro, the study in vivo has been also conducted.

Animals↗