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Biomedical subjects

Y Imamura

Publications and source records attributed to Y Imamura.

At least 73 records · Page 4Linked to original sources
PubMed2000

Novel mutation in RP2 gene in two brothers with X-linked retinitis pigmentosa and mtDNA mutation of leber hereditary optic neuropathy who showed marked differences in clinical severity.

PURPOSE: To report the identification of a novel mutation of the RP2 gene in two Japanese brothers with X-linked retinitis pigmentosa of a differing clinical severity. The mother was a carrier of both retinitis pigmentosa and optic atrophy. METHODS: The older brother had a severe form of retinitis pigmentosa associated with macular degeneration and total optic atrophy, whereas the younger brother presented typical X-linked retinitis pigmentosa. RESULTS: Each patient exhibited a novel 2-bp insertion at codon 278 in exon 3 of the RP2 gene as well as a 11778 mutation in mitochondrial DNA. This suggests that the older brother may have developed Leber hereditary optic neuropathy as well as retinitis pigmentosa. CONCLUSION: Molecular testing confirmed the clinical diagnosis in each case. However, such testing did not explain the differences in the severity of the ophthalmoscopic findings between the two brothers.

Adolescent↗
PubMed2000

Roles of GABAergic inhibition and NMDA receptor subunits in the spatio-temporal integration in the cerebellar cortex of mice.

The cerebellar cortex consists of relatively small numbers of identified neuronal types, which form simple and well-defined layers. However, a direct high-resolution demonstration of spatio-temporal pattern of information transmission there has been lacking. Using an optical recording technique with a membrane-potential sensitive dye, we studied the spatio-temporal pattern of excitation propagation induced by white matter stimulation in the slice preparations. We focused on physiological roles of inhibitory synapses and N-methyl-D-aspartate (NMDA) receptors. White matter stimulation induced postsynaptic long-lasting depolarization in the granular layer and transient depolarization in the molecular layer, respectively. Inhibitory synapses modestly suppressed the amplitude of slow depolarization in the granular layer, whereas they exerted powerful lateral inhibition in the molecular layer. Using mutant mice deficient in NMDA receptor subunits NR2A and/or NR2C, we also demonstrated that the NR2A and NR2C subunits expressed in granule neurons contribute to the early and late components of slow depolarization respectively, and that both subunits cooperatively support the temporal summation of depolarization. Taking into account the anatomical organization of the cerebellar cortex, these results might suggest that the granular layer is specialized more in the temporal integration of input signals and the molecular layer in the spatial integration.

Animals↗
PubMed2000

Retroperitoneoscopic excision of a mesenteric cyst.

Mesenteric cysts are rare intra-abdominal lesions. We present a case of a mesenteric cyst that was discovered by abdominal computed tomography (CT) and excised by retroperitoneoscopic surgery. There have been 10 reports of excision of mesenteric cysts by laparoscopy in the literature, but retroperitoneoscopic resection of such cysts has not been reported. This case suggests that when a mesenteric cyst arises from the ascending or descending colon, the retroperitoneal approach has a lower risk of traumatizing the bowel than does the laparoscopic intra-abdominal approach, and it does not have to compress other intra-abdominal organs.

Adult↗
PubMed2000

Inhibitory effects of flavonoids on rabbit heart carbonyl reductase.

The inhibitory effects of flavonoids (galangin, kaempferol, quercetin, myricetin, morin, and taxifolin) on rabbit heart carbonyl reductase (RHCR) were investigated using 4-benzoylpyridine (4BP) as the substrate. The stereochemical characteristics of the flavonoids were found to be a factor determining their inhibitory potencies toward RHCR. Furthermore, the lipophilicity, and the scavenging or antioxidative effects of the flavonoids were likely to complicate the structure-activity relationship of their inhibitory effects on RHCR. Quercetin inhibited RHCR uncompetitively with respect to NADPH and competitively with respect to 4BP, suggesting that it competes with 4BP at the substrate-binding site of RHCR. RHCR efficiently reduced benzoquinones (1,4-benzoquinone and 2-methyl-1, 4-benzoquinone) and naphthoquinones (1,4-naphthoquinone and menadione). Galangin was a potent inhibitor of RHCR when menadione was used as the substrate, and prevented the formation of the superoxide anion radical in the presence of RHCR, NADPH, and menadione. Flavonoids may be useful compounds for suppressing the cardiotoxicity of quinones by inhibiting RHCR.

Alcohol Oxidoreductases↗
PubMed2000

Janibacter brevis sp. nov., a new trichloroethylene-degrading bacterium isolated from polluted environments.

Two strains that were strongly able to degrade trichloroethylene were isolated from contaminated environmental samples. The isolates are non-motile, aerobic, non-spore-forming, gram-positive coccoid to short rods with cell-wall peptidoglycan containing meso-diaminopimelic acid. The major type of menaquinone is MK-8(H4). The polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylinositol. Mycolic acids were absent. The G+C content of the DNA was 72 mol%. Furthermore, comparison of 16S rDNA sequences shows that the isolates clearly belong to the genus Janibacter. The isolates differ from Janibacter limosus at the species level, as shown by the value for DNA-DNA hybridization. It is therefore proposed that the strains be assigned to the genus Janibacter as Janibacter brevis sp. nov.

Actinomycetales↗
PubMed2000

Catalytic properties for naphthoquinones and partial primary structure of rabbit heart acetohexamide reductase.

The catalytic properties of rabbit heart acetohexamide reductase (RHAR) for naphthoquinones were examined. RHAR efficiently reduced 1,4-naphthoquinone and juglone (5-hydroxy-1,4-naphthoquinone), whereas it had little or no ability to reduce menadione (2-methyl-1,4-naphthoquinone) or plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone). The structural requirements for these four naphthoquinones and one acetohexamide analog, and the kinetic mechanism for the inhibition of acetohexamide reduction by juglone led us to conclude that the 2-methyl group of menadione and plumbagin prevents access of the substrates to the catalytic site of RHAR. Five of six peptides derived from RHAR showed 30-42% residue identities with regions in the amino acid sequence of mouse lung carbonyl reductase (MLCR) belonging to the short-chain dehydrogenase/reductase (SDR) family. The catalytically important residues (Arg-39, Ser-136, Tyr-149 and Lys-153) of MLCR were found in the peptide sequences of RHAR, despite the low residue identities between the two enzymes. RHAR is probably best classified as a member of the SDR family similar to MLCR.

Acetohexamide↗
PubMed2000

Multiple brain metastases from a diffuse sclerosing variant of papillary carcinoma of the thyroid.

We report a 53-yr-old man who presented with multiple brain metastases from a diffuse sclerosing papillary carcinoma of the thyroid. The presenting clinical features were those of an intracranial space-occupying lesion. Three brain tumors, confirmed pathologically to be metastatic thyroid papillary carcinomas, were removed. Two weeks after craniotomy, total thyroidectomy with cervical lymph node dissection was performed. Both lobes of the thyroid were diffusely enlarged and firm with a dominant mass. Histologically, the tumor was characterized by a combination of bilateral diffuse involvement of the gland, marked fibrosis, squamous metaplasia, abundant psammoma bodies, lymphocytic infiltration, frequent lymphatic and blood vessel permeation of the tumor, and typical elements of a conventional papillary carcinoma. In addition to these histologic findings, elements of other papillary carcinoma variants such as follicular and tall cell variants were also found focally. Twenty-three of twenty-four resected bilateral lymph nodes showed metastases of papillary carcinoma. Although the diffuse sclerosing variant of papillary carcinoma of the thyroid seems to be recognized as an aggressive variant of papillary carcinoma, there is no previous report of brain metastasis from this variant.

Journal Article↗
PubMed2000

Interleukin-10 expression in intestine of Crohn disease.

Inflammatory bowel diseases are considered to be related to dysregulation of pro- and anti-inflammatory cytokines in the intestinal wall. We investigated the levels of TNFalpha, IFNgamma, and IL-10 mRNA expression in intestinal tissues resected from the patients with Crohn disease (CD) (n=29), ulcerative colitis (UC) (n=8), and controls (n=8) using reverse transcription-polymerase chain reaction (RT-PCR). In addition, we examined the relationship between the expression of these cytokine mRNA and their clinical conditions using CD activity index (CDAI) and Nutritional Surgical Risk Index (NSRI). Compared with controls, tissues in CD showed high levels of TNFalpha and IFNgamma mRNA expression both in inflamed and non-inflamed tissues, and showed high levels of IL-10 mRNA expression in inflamed tissues. In UC, high levels of IL-10 mRNA expression were detected both in inflamed and non-inflamed UC tissues, while those of TNFalpha and IFNgamma were not. In 80% of CD tissues (n=23), levels of IL-10 and TNFalpha expression were interrelated. While the remaining tissues (n=6) showed low levels of IL-10 expression despite high levels of TNFalpha expression in inflamed CD tissues, and 4 of these 6 patients had high CDAI and low NSRI. Furthermore, in low nutritional CD patients (NSRI <40, n=13), the levels of IL-10 mRNA to inhibit pro-inflammatory cytokines were poorer than in good nutritional patients (NSRI >/=40, n=16). These findings suggest the overexpressions of TNFalpha and IFNgamma in CD, and less producibility of IL-10 against these cytokine might lead to development of severe CD.

Adolescent↗
PubMed2000

Generation of pro-inflammatory and anti-inflammatory cytokines in the gut in zymosan-induced peritonitis.

In major systemic inflammation such as severe peritonitis, various pro-inflammatory cytokines, such as TNF-alpha, IL-1 beta and IL-6, play important roles in the development of multiple organ dysfunction syndrome (MODS). The purpose of this study was to investigate the outflow of pro-inflammatory and anti-inflammatory cytokines from the efferent mesenteric lymphatic vessels under peritonitis. Mesenteric lymph samples were collected from adult male rats at 2, 4, 6, 8 and 10 hr after an intraperitoneal injection of zymosan at a dosage of 0.1 mg/g (non-lethal dose) or 0.5 mg/g (lethal dose). Blood samples were obtained at 10 hr after zymosan administration. The amounts of drained TNF-alpha and IL-6 in the lymph peaked at 2-4 hr and 4-8 hr after zymosan administration, respectively. The amounts of drained IL-10 in the lymph gradually increased until 10 hr. The amounts of drained TNF-alpha and IL-10 in the mesenteric lymph were significantly correlated with the dosage of zymosan. In conclusion, under intraperitoneal inflammation, pro-inflammatory cytokines (TNF-alpha and IL-6) increased in the mesenteric lymph and were drained into circulation. IL-10, one of the anti-inflammatory cytokines, also increased in the mesenteric lymph after several hours' delay and its increase was remarkable in several inflammations. These findings suggested that the gut might be one of the pro-inflammatory and anti-inflammatory cytokine-generating organs under peritonitis. The lymph-drained amounts of each cytokine under peritonitis are considered to differ with the time or severity of inflammation, which may cause different conditions in patients due to the imbalance of pro-inflammatory and anti-inflammatory cytokines.

Animals↗
PubMed2000

No association of borna disease virus with psychiatric disorders among patients in northern Kyushu, Japan.

There is controversy over the prevalence of Borna disease virus (BDV) antibodies and its RNA in the peripheral blood mononuclear cells (PBMCs) of psychiatric patients, and the contribution of BDV to human psychiatric disorders. We examined 299 plasma and 229 PBMC samples. No plasma samples were positive for BDV-p40, p24 or gp18 antibodies by western blot analysis. The prevalence of BDV RNA in the psychiatric (schizophrenic) patients (1.8%) was not significantly different from that in the healthy volunteers (0.6%). The nucleotide sequences of BDV p40 and p24 were highly conserved with those of BDV He/80. Our results suggested that there is a lack of association between BDV infection and psychiatric disorders among the patients in Northern Kyushu, Japan.

Adolescent↗
PubMed2000

High telomerase activity is an independent prognostic indicator of poor outcome in colorectal cancer.

Telomerase activity and altered telomere length have been extensively studied in many kinds of malignant tumors for clinical diagnostic and/or prognostic utilities. In the present study, we investigated telomerase activity and telomere length in colorectal cancers and noncancerous colonic mucosa specimens in 100 patients between 1991 and 1996. To determine whether the level of telomerase activity or telomere length is a prognostic indicator of patient outcome, we followed these patients more than 3 years after surgery. Among 100 primary colorectal cancer specimens, 96 specimens had telomerase activity. Because noncancerous mucosa has some detectable telomerase activity, we divided the levels of telomerase activity into three categories: high (>50-fold more than that in noncancerous mucosa); moderate (10- to 50-fold); and low (<10-fold) levels. Among 100 cancer tissues, 28 showed moderate telomerase activity and 44 showed high telomerase activity. The frequency of tumors with moderate or high telomerase activity showed no significant relationship with any clinicopathological factors. The prognosis of the patients with high telomerase activity was significantly worse than that for patients with moderate and low telomerase activity (P < 0.01). Among the 87 patients with curative surgery, disease-free survival rate of those with high telomerase activity was also significantly poorer (P < 0.01). These results indicate that a high level of telomerase activity may be an independent prognosis-predicting factor in the patients with colorectal cancer.

Adult↗
PubMed2000

Early progression stage of malignancy of uterine cervical dysplasia as revealed by immunohistochemical demonstration of increased DNA-instability.

The degree of DNA-instability as revealed by the immunohistochemical staining with anti-single-stranded DNA antibody after acid hydrolysis (DNA-instability test) was used as a marker of malignancy. This was applied to mild dysplasia (42 cases), moderate dysplasia (43 cases), severe dysplasia (27 cases), squamous cell carcinoma in situ (CIS) (21 cases), invasive squamous cell carcinoma (SCC) (31 cases) and normal (7 cases) human uterine cervix. The expression of tumour suppressor gene p53 and oncogene bcl-2 was detected immunohistochemically. Proliferative activity was evaluated by PCNA immumohistochemistry and the quantitative analysis of the number, mean area, the largest area and maximum shape irregularities of AgNOR in a nucleus were performed for all these cases. The distribution of numeric chromosomal aberrations of chromosome 17 was also investigated in some of these cases. The results showed that 31 SCC (100%), 21 CIS (100%), 21 severe dysplasia (77.77%), 28 moderate dysplasia (65.11%), and 14 mild dysplasia (33.33%) were positively stained by the DNA-instability test diffusely or sporadically, indicating their malignancy. Reflecting the malignant character, these cases showed a remarkable increase in the PCNA-index with the loss of polarity of PCNA positive cell distribution and also an increase in number, mean and largest sizes and maximum shape irregularity of AgNOR dots. The mean chromosome index for chromosome 17, p53 and bcl-2 immunostaining positivity were also found to be significantly increased in moderate and severe dysplasia and in cancerous cases in comparison to normal and mild dysplasia cases. Moreover, the DNA-instability-test positive dysplasia cases showed statistically significant increased values of PCNA-index, AgNOR parameters, mean chromosome index, p53 and bcl-2 expression in comparison to those of DNA-instability-test negative dysplasia cases. In conclusion, some mild dysplasia (33.33%) and most of the moderate (65.11%) and severe dysplasia (77.77%) were regarded as malignant in nature, existing at an early stage of progression of malignancy.

Carcinoma in Situ↗
PubMed2000

Expression of various growth factors for cell proliferation and cytodifferentiation during fracture repair of bone.

We examined immunohistochemically the fracture repair process in rat tibial bone using antibodies to PCNA, BMP2, TGF-beta 1,-2,-3, TGF-beta R1,-R2, bFGF, bFGFR, PDGF, VEGF, and S-100. The peak level of cell proliferation as revealed by PCNA labelling appeared first in primitive mesenchymal cells and inflammatory cells at the fracture edges and neighboring periosteum at 2-days after fracture, followed by the peaks of periosteal primitive fibroblasts and chondroblasts, which appeared at fracture edges at 3- and 4-days after fracture, respectively. BMP2 was weakly positive in primitive mesenchymal cells, osteoblasts and chondroblasts. At 3-days post-fracture, periosteal osteoblasts produced osteoid tissue and callus with marrow spaces lined by osteoblasts and osteoclasts, and all primitive mesenchymal cells and osteoblasts were positive for TGF-beta 1,-2,-3, and TGF-beta R1,-R2. They were also positive for vascular growth factors bFGF, FGFR and PDGF, but negative for VEGF, and the peak of PCNA labelling of vascular endothelial cells in the marrow space was delayed to 4-days after fracture. Chondroblasts at fracture edges produced hypertrophic chondrocytes at 5-days after fracture and they were positive for TGF-beta 1,-2,-3, and TGF-beta R1,-R2. Primitive chondroblasts were positive for vascular growth factors VEGF as well as bFGF, FGFR, and the peak of PCNA labelling of vascular endothelial cells in the cartilage was at 5-days after fracture. Hypertrophic chondrocytes were also positive for these growth factors but negative for bFGF and bFGFR. S-100 protein-induced calcification was only positive on chondroblasts and hypertrophic chondrocytes. At 7-days after fracture, bone began to be formed from the cartilage at fracture edges, by a process similar to bone formation in the growth plate. Enchondral ossification established a bridge between both fracture edges and periosteal membranous ossification encompassed the fracture site like a sheath at 14 day after fracture. Our study of fracture repair of bone indicates that this process is complex and occurs through various steps involving various growth factors.

Alkaline Phosphatase↗