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Biomedical subjects

A Kitamura

Publications and source records attributed to A Kitamura.

At least 19 recordsLinked to original sources

Chronic membrane depolarization-induced morphological alteration of developing neurons.

During development of CNS, young neurons experience various stimuli, and thereafter differentiate to mature neurons in an activity-dependent manner. Membrane depolarization acts as an inducer of excitability and various signals in the neurons, which can be used as a model of neuronal activity. However, the mechanisms of the influence of membrane depolarization on neuronal differentiation have not been fully understood. Therefore, we investigated the effect of membrane depolarization on morphology of spines and generation of valid electrical activity. Using rat hippocampal cultures treated from the plating day with or without high KCl (35 mM, termed HK), we directly observed living neurons transfected with green fluorescence protein-expressing plasmid through a two-photon laser scanning confocal microscope and electrophysiological recording using a patch-clamp technique. Compared with controls, the neurons cultured with HK for 3 days in vitro (DIV) showed marked filopodia-like protrusions as well as an increase in the number of spines, but those cultured with HK for 6 DIV profoundly lost these spines, resulting in a small number of fine filopodia-like protrusions proximally and on the cell body, and a smooth surface of distal dendrites. Electrophysiological recordings showed no spontaneous responses in 6 DIV HK-treated neurons. Moreover, addition of an N-methyl-D-aspartate receptor (NMDAR) antagonist to HK-treated neurons blocked the shrinkage and decrease in the number of filopodia-like protrusions significantly. These findings suggest that membrane depolarization of developing neurons induces synaptogenesis in the early stages of development but chronic treatment with HK causes pathological changes through NMDAR, and that there may be alternative mechanisms for the physiological differentiation of neurons in later developmental stages.

2-Amino-5-phosphonovalerate↗

Sound spectrogram analysis in patients receiving Kawahara's surgical voice restoration for advanced carcinoma of the hypopharynx and cervical esophagus.

Loss of voice after total laryngectomy is a major concern that has prompted much effort to develop methods of surgical voice restoration. In 1992, Kawahara described a tracheocolic shunt for voice restoration using a revascularized ileocolic graft. With this method, aspiration through the phonatory shunt is prevented by the ileocolic valve (Bauhin's valve), while vocalization is allowed. The purpose of this study was to use sound spectrogram analysis to evaluate voices surgically restored in that way. Between 2002 and 2005, 10 consecutive patients underwent laryngopharyngoesophagectomy with Kawahara's surgical voice restoration for advanced carcinoma of the hypopharynx and/or cervical esophagus at Akita University Hospital, Japan. We then used sound spectrography to analyze and compare the voices of patients receiving Kawahara's voice restoration, against healthy volunteers and patients who underwent the same surgery without voice restoration and spoke using an electronic larynx. We also evaluated the intelligibility of conversation and performed a listening test. The sound spectrograms showed that when produced by the electronic larynx, consonant sounds and voice frequencies below 300 Hz were not clearly recognized. By contrast, in patients who received Kawahara's surgical voice restoration, consonant and vowel sounds at frequencies above and below 300 Hz were clearly recognized. Although conversation was intelligible with both Kawahara's surgical voice restoration and the electronic device, listeners judged the voice produced by the former to be superior. Thus, the voice produced by Kawahara's surgical voice restoration is superior to that produced by the electronic larynx.

Aged↗

Plasma fibrinogen level and the risk of major cardiovascular diseases and nonvascular mortality: an individual participant meta-analysis.

CONTEXT: Plasma fibrinogen levels may be associated with the risk of coronary heart disease (CHD) and stroke. OBJECTIVE: To assess the relationships of fibrinogen levels with risk of major vascular and with risk of nonvascular outcomes based on individual participant data. DATA SOURCES: Relevant studies were identified by computer-assisted searches, hand searches of reference lists, and personal communication with relevant investigators. STUDY SELECTION: All identified prospective studies were included with information available on baseline fibrinogen levels and details of subsequent major vascular morbidity and/or cause-specific mortality during at least 1 year of follow-up. Studies were excluded if they recruited participants on the basis of having had a previous history of cardiovascular disease; participants with known preexisting CHD or stroke were excluded. DATA EXTRACTION: Individual records were provided on each of 154,211 participants in 31 prospective studies. During 1.38 million person-years of follow-up, there were 6944 first nonfatal myocardial infarctions or stroke events and 13,210 deaths. Cause-specific mortality was generally available. Analyses involved proportional hazards modeling with adjustment for confounding by known cardiovascular risk factors and for regression dilution bias. DATA SYNTHESIS: Within each age group considered (40-59, 60-69, and > or =70 years), there was an approximately log-linear association with usual fibrinogen level for the risk of any CHD, any stroke, other vascular (eg, non-CHD, nonstroke) mortality, and nonvascular mortality. There was no evidence of a threshold within the range of usual fibrinogen level studied at any age. The age- and sex- adjusted hazard ratio per 1-g/L increase in usual fibrinogen level for CHD was 2.42 (95% confidence interval [CI], 2.24-2.60); stroke, 2.06 (95% CI, 1.83-2.33); other vascular mortality, 2.76 (95% CI, 2.28-3.35); and nonvascular mortality, 2.03 (95% CI, 1.90-2.18). The hazard ratios for CHD and stroke were reduced to about 1.8 after further adjustment for measured values of several established vascular risk factors. In a subset of 7011 participants with available C-reactive protein values, the findings for CHD were essentially unchanged following additional adjustment for C-reactive protein. The associations of fibrinogen level with CHD or stroke did not differ substantially according to sex, smoking, blood pressure, blood lipid levels, or several features of study design. CONCLUSIONS: In this large individual participant meta-analysis, moderately strong associations were found between usual plasma fibrinogen level and the risks of CHD, stroke, other vascular mortality, and nonvascular mortality in a wide range of circumstances in healthy middle-aged adults. Assessment of any causal relevance of elevated fibrinogen levels to disease requires additional research.

Adult↗

Novel transdermal photodynamic therapy using ATX-S10.Na(II) induces apoptosis of synovial fibroblasts and ameliorates collagen antibody-induced arthritis in mice.

We aimed to test the effect of transdermal photodynamic therapy (PDT) on synovial proliferation in vitro and in vivo, using a novel photosensitizer, ATX-S10.Na(II). Synovial fibroblasts were obtained from patients with RA (RASF). Cell viability with or without PDT was determined by MTT assay. Cell morphology was examined by light and transmission electron microscopy. DNA fragmentation was labeled by TUNEL stain. Collagen antibody-induced arthritis (CAIA) was induced in DBA/1 mice, and the effects of transdermal PDT were evaluated by clinical and histological examination. PDT showed drug concentration-dependent and laser dose-dependent cytotoxicity on RASF. TUNEL stain and TEM study revealed the induction of apoptotic cell death of RASF. Transdermal PDT significantly reduced clinical arthritis and synovial inflammation in this model of arthritis. These results suggest that transdermal PDT using ATX-S10.Na(II) might be a novel less invasive treatment strategy for small joint arthritis and tenosynovitis.

Animals↗

Primary lymphoma arising in the nasal cavity among Japanese.

AIMS: Most lymphomas arising in the nasal cavity are thought to be of natural killer (NK) cell origin. However, some reports indicate that T- and B-cell lymphomas may also primarily arise in the nasal cavity. We therefore studied lymphomas arising in the nasal cavity both histologically and immunohistochemically. METHODS AND RESULTS: Of the 32 cases investigated, 20 cases were also available as fresh frozen specimens. We diagnosed 31 cases as extranodal NK/T-cell lymphoma and one as plasmacytoma. The neoplastic cells were immunoreactive for CD3 (polyclonal) 31/31, LMP-1 12/31, CD20 (L26) 0/31, granzyme B 30/31, TIA-1 30/30, CD56 (123C3) 29/31, CD4 0/31 and CD8 3/31. In situ hybridization for Epstein-Barr virus-encoded small RNA-1 (EBER-1) was detected in 31/31. In frozen tissue sections, neoplastic cells mostly showed CD3 (Leu4)-, CD4 (Leu3a)-, CD5 (Leu1)-, CD8 (Leu2)-, CD16 (Leu11)-, CD56 (Leu19)+, betaF1-, TCRdelta1-, perforin+, CD94+ phenotypes. These immunohistochemical findings indicate their NK cell origin. In three cases, neoplastic cells were positive for CD8. In one of these cases, neoplastic cells were positive for CD8beta and Valpha24, suggesting their NKT-cell origin. CONCLUSIONS: Our present study indicates that primary lymphomas arising in the nasal cavity are mostly of NK cell derivation. Our present study also suggests that a small number of cases are derived from NKT-cells.

Adult↗

Type 2 diabetes and risk of non-embolic ischaemic stroke in Japanese men and women.

AIMS/HYPOTHESIS: The aim of this study was to examine the relationship between type 2 diabetes and risk of ischaemic stroke in Asian populations. METHODS: We conducted a 17-year prospective cohort study in 10,582 Japanese individuals (4287 men and 6295 women) aged 40-69 years living in five communities in Japan. All subjects were free of stroke and CHD at baseline. Diabetes was defined as a fasting glucose level of >/=7.0 mmol/l, a non-fasting glucose of >/=11.1 mmol/l, or receiving medication for diabetes. RESULTS: The risk of non-embolic ischaemic stroke was approximately two-fold higher in diabetic subjects than in subjects with normal glucose levels. The multivariate relative risk after adjustment for age, community, hypertensive status, BMI, triceps and subscapular skinfold thickness (TSF and SSF), and other known cardiovascular risk factors was 1.8 (95% CI 1.0-3.2) for men and 2.2 (1.2-4.0) for women. This excess risk was primarily observed among non-hypertensive subjects and individuals with higher values for measures of adiposity (BMI, TSF and SSF values above the median), particularly those with higher values for SSF. The association between non-embolic ischaemic stroke and glucose abnormality was particularly strong among non-hypertensive subjects with higher SSF values: the multivariate relative risk was 1.9 (1.0-3.7) for borderline diabetes and 4.9 (2.5-9.5) for diabetes. CONCLUSIONS/INTERPRETATION: In this cohort, type 2 diabetes was a significant risk factor for non-embolic ischaemic stroke, particularly in non-hypertensive and non-lean individuals. Due to the nationwide decrease in blood pressure and increase in mean BMI among the Japanese population, with current levels approaching those observed in Western countries, the impact of glucose abnormalities on risk of ischaemic stroke represents a forthcoming public health issue in Japan.

Adult↗

Endothelin-1 is a potent stimulator of alpha1beta1 integrin-mediated collagen matrix remodeling by rat mesangial cells.

Endothelin-1 (ET) is known to stimulate mesangial cell (MC) proliferation, extracellular matrix (ECM) synthesis, and thereby contribute to the progression of glomerulonephritis (GN). To clarify the molecular and cellular mechanisms of how ET is involved in the development of glomerular sclerosis, we investigated the influence of ET on the MC-alpha1beta1 integrin-mediated collagen matrix reorganization using a collagen gel contraction assay. ET enhanced MC-alpha1beta1 integrin-mediated gel contraction in a dose-dependent manner. Addition of the endothelin A (ETA) receptor antagonist, BQ123, into collagen gels abolished ET-induced gel contraction by MC. Cell behavior involved in ET-induced gel contraction was investigated in combination with function-blocking anti-alpha1-integrin antibody. Migration and adhesion assays revealed that ET stimulated alpha1beta1 integrin-mediated MC migration but did not influence cell adhesion to type I collagen (collagen I). Integrin-function blocking studies using anti-alpha1 integrin antibody indicated that MC-alpha1beta1 integrin is required not only for collagen-dependent migration, but also for gel contraction. Zymography showed that ET increased MC matrix metalloproteinase-2 (MMP-2) activity in a dose-dependent manner during MC-induced gel contraction process. Finally, flow cytometry analysis indicated that ET did not affect the cell surface expression of the MC-alpha1beta1 integrin within the collagen gel. These data suggested that ET promotes collagen matrix reorganization through the enhancement of MC-alpha1beta1 integrin-dependent migration and MMP-2 activity. We therefore conclude that ET is a potential molecule inducing pathological collagen matrix remodeling observed in progressive GN.

Animals↗

Reduced Fhit expression is associated with mismatch repair deficiency in human advanced colorectal carcinoma.

The Fragile Histidine Triad gene, encompassing the FRA3B fragile site at chromosome 3p14.2, is a candidate tumour suppressor gene involved in multiple tumour types including colorectal carcinomas. Recently, it has been reported that the Fragile Histidine Triad gene may be a target of damage in a fraction of mismatch deficient tumours. To explore this hypothesis, we analysed both Fragile histidine triad and mismatch repair protein (Msh2 and Mlh1) expression using immumohistochemical methods in 52 advanced colorectal carcinomas (19 well-, 17 moderately-, and 16 poorly-differentiated). In addition, we examined whether the Fragile histidine triad and mismatch repair protein expression correlated with p53 expression and clinicopathological findings. Significant loss or reduction of Fragile histidine triad expression was noted in 18 of the 52 (34.6%) advanced colorectal carcinomas: 2 (10.5%) well-differentiated, 3 (17.6%) moderately-differentiated, 13 (81.3%) poorly-differentiated carcinomas, the frequency being significantly higher in the latter than that in the former two (P<0.0001). Loss of mismatch repair protein (mainly, Mlh1) expression was detected in 21 of the 52 (40.4%) colorectal carcinomas. Moreover, reduced Fragile histidine triad expression was significantly associated with absence of mismatch repair protein expression in the advanced colorectal carcinomas (P<0.0001). However, the Fragile histidine triad and mismatch repair protein expression was not significantly associated with p53 expression. These results suggested that reduced Fragile histidine triad expression might be correlated with mismatch repair expression, but not with p53 expression.

Acid Anhydride Hydrolases↗

Intercellular adhesion molecule-1 (ICAM-1) polymorphism is associated with diabetic retinopathy in Type 2 diabetes mellitus.

AIMS: Leucocyte adhesion to the diabetic retinal vasculature has been implicated in the pathogenesis of diabetic retinopathy. We evaluated the relationship between genetic polymorphisms in leucocyte and endothelial cell adhesion molecules and diabetic retinopathy in Type 2 diabetes mellitus. METHODS: We determined ICAM-1, platelet endothelial cell adhesion molecule-1 (PECAM-1), and leucocyte endothelial adhesion molecule-1 (LECAM-1) genotypes in 81 patients with and 50 without diabetic retinopathy. RESULTS: The frequency of ICAM-1 469KK genotype and K allele were significantly higher in the patients with diabetic retinopathy than in those without retinopathy (genotype 42% vs. 20%, chi2 = 6.70, P = 0.035; allele 66% vs. 50%, chi2 = 6.49, P = 0.011). With regard to the PECAM-1 V125L and LECAM-1 P213S polymorphisms, there were no significant associations between the distribution of genotypes or allele frequencies and the presence of diabetic retinopathy. Independent of other risk factors, the ICAM-1 469KK genotype was associated with a 3.51-fold increased risk for retinopathy. CONCLUSIONS: These data suggest that the ICAM-1 469KK genotype could be a genetic risk factor for retinopathy in Type 2 diabetes mellitus.

Age of Onset↗

Interleukin-6 polymorphism (-634C/G) in the promotor region and the progression of diabetic nephropathy in type 2 diabetes.

AIMS: Interleukin-6 (IL-6) is a multifunctional cytokine produced by many different cell types, including glomerular mesangial cells. Recently, a novel C/G polymorphism at position -634 in the promotor region of the IL-6 gene has been reported. The aim of this study was to investigate whether the -634C/G polymorphism is associated with an increased risk for progression to diabetic nephropathy as well as elevated levels of IL-6 secretion by peripheral blood mononuclear cells. METHODS: The frequency of the -634C/G polymorphism was determined in Japanese patients with Type 2 diabetes and either normoalbuminuria (n = 162), microalbuminuria (n = 138), or macroalbuminuria (n = 154) by polymerase chain reaction-restriction fragment length polymorphism analysis. The level of IL-6 secretion in relation to genotype was assessed in lipopolysaccharide or advanced glycation end products-stimulated IL-6 secretion by peripheral mononuclear cells. RESULTS: The frequency of the -634G/G genotype and -634*G allele was significantly increased in the patients with macroalbuminuria compared with patients with normoalbuminuria (genotype: chi2 = 6.787, Pc = 0.0368; allele: chi2 = 9.080, Pc = 0.0104). Stepwise multiple regression analysis in these patients showed that hypertension (F = 40.48) and IL-6-634 gene polymorphism (F = 5.48) were the relevant variables for the progression of Type 2 diabetic nephropathy. Analysis of the IL-6 secretion data revealed that individuals carrying the -634*G allele had a higher IL-6 secretion capacity than those without the *G allele (P < 0.05). CONCLUSIONS: These results suggest that the IL-6-634C/G polymorphism may be a possible genetic susceptibility factor for the progression of diabetic nephropathy.

Diabetes Mellitus, Type 2↗

Effects of sumatriptan on cerebral blood flow under normo- and hypercapnia in rats.

To investigate further the pharmacological mechanism of an anti-migraine drug, sumatriptan, a 5-HT1B/1D receptor agonist, we studied its effect on the cerebral circulation in seven anaesthetized rats, particularly during hypercapnia. After injection of 0.6 or 6.0 microg/kg sumatriptan succinate, no significant change in cerebral blood flow (CBF) was observed either in the striatum or in the parietal cortex. The increase in CBF both in the parietal cortex and the striatum during 5% CO2 inhalation was significantly less when sumatriptan succinate 6.0 microg/kg was injected. Sumatriptan appeared to have a vasoconstrictor effect on the relaxed vessels by CO2 inhalation. This mechanism might be attributable to vasoconstriction through activation of 5-HT1B receptors located in the vascular smooth muscle rather than 5-HT1B receptors in the vascular adventitia.

Animals↗

Changes in the populations of mitotic and apoptotic cells in white follicles during atresia in hens.

The aim of this study was to determine whether the population of mitotic cells changes in correlation with apoptotic cell population in follicular tissues during atresia of white follicles in hens. Hens were injected with 5-bromo-2'-deoxyuridine (BrdU) 1 h before tissue collection. The small white follicles were classified as healthy follicles and as early or late atretic follicles by histological observation. Mitotic and apoptotic cells were determined by immunocytochemistry for BrdU and terminal deoxytranceferase-mediated dUTP nick end labeling (TUNEL), respectively. The BrdU labeling was observed in some of the granulosa cells and thecal fibroblast-like cells in healthy follicles, whereas the population of the labeled cells was reduced in the granulosa and theca layers of atretic follicles. The image analysis confirmed that the frequency of BrdU-positive cells declined significantly in the granulosa and theca layers of early atretic follicles compared with those of healthy follicles. In contrast, the TUNEL-positive cells were negligible in healthy follicles. However, they were localized in the granulosa and theca layers of early and late atretic follicles, and those in the theca layer were more inside than outside. The frequency of TUNEL-positive cells was significantly increased with the progress of atretic changes. These results suggest that the population of mitotic cells decreases in association with increase of apoptotic cells during the atretic process of white follicles.

Animals↗

Expression of p68 RNA helicase is closely related to the early stage of adipocyte differentiation of mouse 3T3-L1 cells.

We have previously identified the genes expressed early in the differentiation of mouse 3T3-L1 cells into adipocytes. Since these genes were isolated as small fragments, many were unknown. In this study, we have cloned two full-length cDNAs and identified them as p68 RNA helicase and mc3s5/mtCLIC. The expression of these genes was rapidly induced, and specific to the adipocyte differentiation. When the expression of p68 RNA helicase was inhibited using an inducible antisense system, the differentiation into adipocytes was partially blocked, and the expression levels of some marker genes decreased. These findings strongly indicate that the expression of the above two genes was closely related to the adipocyte differentiation, and p68 RNA helicase in particular is crucial to the differentiation.

3T3 Cells↗

Activity-dependent transfer of brain-derived neurotrophic factor to postsynaptic neurons.

Neurotrophins such as brain-derived neurotrophic factor (BDNF) are thought to be transferred from post- to presynaptic neurons and to be involved in the formation and plasticity of neural circuits. However, direct evidence for a transneuronal transfer of BDNF and its relation to neuronal activity remains elusive. We simultaneously injected complementary DNAs of green fluorescent protein (GFP)-tagged BDNF and red fluorescence protein into the nucleus of single neurons and visualized expression, localization, and transport of BDNF in living neurons. Fluorescent puncta representing BDNF moved in axons in the anterograde direction, though some moved retrogradely, and transferred to postsynaptic neurons in an activity-dependent manner.

Animals↗

Serum triglycerides and risk of coronary heart disease among Japanese men and women.

To examine the relation of triglycerides with coronary heart disease among populations with low mean total cholesterol, the authors conducted a 15.5-year prospective study ending in 1997 of 11,068 Japanese aged 40-69 years (4,452 men and 6,616 women with mean total cholesterol = 4.73 mmol/liter and 5.03 mmol/liter, respectively), initially free of coronary heart disease or stroke. There were 236 coronary heart disease events comprising 133 myocardial infarctions, 68 angina pectoris events, and 44 sudden cardiac deaths. The coronary heart disease incidence was greater in a dose-response manner across increasing quartiles of nonfasting triglycerides for both sexes. The multivariate relative risk of coronary heart disease adjusting for coronary risk factors and time since last meal associated with a 1-mmol/liter increase in triglycerides was 1.29 (95% confidence interval (CI): 1.09, 1.53; p = 0.004) for men and 1.42 (95% CI: 1.15, 1.75; p = 0.001) for women. The trend was similar for myocardial infarction, angina pectoris, and sudden cardiac death. The relation of triglycerides with coronary heart disease was not influenced materially by total cholesterol levels or, in a subsample analysis (51% of total sample), by high density lipoprotein cholesterol levels. Nonfasting serum triglycerides predict the incidence of coronary heart disease among Japanese men and women who possess low mean values of total cholesterol. Further adjustment for high density lipoprotein cholesterol suggests an independent role of triglycerides on the coronary heart disease risk.

Adult↗

Trapping of 1,8-biradical intermediates by molecular oxygen in photocycloaddition of naphthyl-N-(naphthylcarbonyl)carboxamides; formation of novel 1,8-epidioxides and evidence of stepwise aromatic cycloaddition.

The photocycloaddition reaction of naphthyl-N-(naphthylcarbonyl)carboxamides (1) was examined under argon and oxygen atmospheres. In addition to the [2 + 2] and [4 + 4] cycloadducts, 3 and 4, respectively, novel 1,8-epidioxides (5) were formed under oxygen atmosphere. The transient absorption at lambda max of 360 nm with the lifetime of 360 ns was observed by laser flash photolysis of 1c and was interpreted as the absorption of biradical intermediate 2. On the basis of the anti stereochemistry of 5, which was different from that of the major [4 + 4] cycloadducts, syn-4, it was deduced that equilibrium between biradical intermediates syn-2 and anti-2 would exist. Retro [2 + 2] cycloaddition of 3 was responsible for the efficient trapping of the biradical intermediate with molecular oxygen. The photocycloaddition of the anthryl derivatives, 9-anthryl-N-(methylethyl)-N-(naphthylcarbonyl)carboxamides (7), afforded the [4 + 4] cycloadducts (8) exclusively in a quantitative yield even under oxygen atmosphere. The absence of trapping with molecular oxygen was interpreted to be due to the lack of retro [4 + 4] cycloaddition of 8.

Journal Article↗

Reduced Fhit expression occurs in the early stage of esophageal tumorigenesis: no correlation with p53 expression and apoptosis.

The FHIT gene, encompassing the FRA3B fragile site at chromosome 3p14.2, is a candidate tumor suppressor gene involved in multiple tumors, including esophageal carcinoma. We analyzed Fhit expression using an immunohistochemical method in invasive carcinoma, carcinoma in situ (CIS) and dysplasia, in paraffin sections of 75 esophageal squamous cell carcinomas (ESCs) to further elucidate the role of Fhit protein in esophageal carcinogenesis. In addition, we also examined whether Fhit expression correlated with p53 expression and apoptosis. Compared to adjacent normal mucosa, significant loss or reduction of Fhit expression was noted in 67 of 75 (89.3%) invasive ESCs, in 13 of 19 (68.4%) CIS lesions, and in 10 of 23 (43.5%) dysplastic lesions. There was a progressive loss or reduction of Fhit expression with progressive increases in the severity of histopathological changes (p < 0.001). However, there was no association between Fhit expression and clinicopathological findings, including tumor stage, lymph node metastasis, or overall survival. Moreover, Fhit expression was not significantly associated with p53 expression and apoptosis. These results indicate that abnormal Fhit expression is a common event in the early stage of ESC development and may occur independently of p53 expression and apoptosis mechanisms.

Acid Anhydride Hydrolases↗