Biomedical subjects

Y Higuchi

Publications and source records attributed to Y Higuchi.

At least 91 records · Page 5Linked to original sources

PubMed1998

Basis for monomer stabilization in Rhodopseudomonas palustris cytochrome c' derived from the crystal structure.

The crystal structure of an unusual monomeric cytochrome c' from Rhodopseudomonas palustris (RPCP) has been determined at 2.3 A resolution. RPCP has the four-helix (helices A, B, C and D) bundle structure similar to dimeric cytochromes c'. However the amino acid composition of the surface of helices A and B in RPCP is remarkably different from that of the dimeric cytochromes c'. This surface forms the dimer interface in the latter proteins. RPCP has seven charged residues on this surface contrary to the dimeric cytochromes c', which have only two or three charged groups on the corresponding surface. Moreover, hydrophobic residues on this surface of RPCP are two to three times fewer than in dimeric cytochromes c'. As a result of the difference in amino acid composition, the A-B surface of RPCP is rather hydrophilic compared with dimeric cytochromes c'. We thus suggest that RPCP is monomeric in solution because of the hydrophilic nature of the A-B surface. The amino acid composition of the A-B surface is similar to that of Rhodobacter capsulatus cytochrome c' (RCCP), which is an equilibrium admixture of monomer and dimer. The charge distribution of the A-B surface in RCCP, however, is considerably different from that of RPCP. Due to the difference, RCCP can form dimers by both ionic and hydrophobic interactions. These dimers are quite different from those in proteins which form strong dimers such as in Chromatium vinosum, Rhodospirillum rubrum, Rhodospirillum molischianum and Alcaligenes. Cytochrome c' can be classified into two types. Type 1 cytochromes c' have hydrophobic A-B surfaces and they are globular. The A-B surface of type 2 cytochromes c' is hydrophilic and they take a monomeric or flattened dimeric form.

Amino Acid Sequence↗

PubMed1998

Estimation of shunt flow in coronary-pulmonary fistula by lung perfusion scintigraphy with technetium-99m macroaggregated albumin.

The shunt flow from the coronary artery to pulmonary arteries was evaluated in 6 patients with coronary-pulmonary fistula by lung perfusion scintigraphy with technetium-99m macroaggregated albumin. In 2 patients, whose degree of visualization of pulmonary arteries by coronary angiography was relatively high, lung perfusion scintigrams demonstrated the defects at the distal of coronary-pulmonary fistulas.

Aged↗

PubMed1998

Crystallization and preliminary X-ray diffraction study of lactonohydrolase from Fusarium oxysporum.

The lactonohydrolase from the fungus Fusarium oxysporum AKU 3702 was crystallized by the vapour-diffusion procedure in the presence of polyethylene glycol 4000 as a precipitant. The crystals belong to the monoclinic space group P21 with unit-cell parameters a = 156, b = 100, c = 94.1 A, beta = 91.7 degrees. Assuming that there are two lactonohydrolase-dimer molecules in the asymmetric unit, the crystal volume per unit molecular mass, Vm, is calculated to be 2.94 A3 Da-1.

Carboxylic Ester Hydrolases↗

PubMed1998

Search for genes involved in UV-resistance in human cells by mRNA differential display: increased transcriptional expression of nucleophosmin and T-plastin genes in association with the resistance.

UVr-10 UV-resistant cells were established from UV-sensitive human RSb cells. We searched here for genes expressed differentially between UVr-10 and RSb cells using a differential display method to elucidate the molecular mechanisms underlying the UV-resistance. Thirteen candidate cDNA fragments were obtained from 514 mRNA species first screened. Among the cDNA fragments, 3 revealed increased mRNA expression in UVr-10 cells compared with RSb cells by Northern analysis. Nucleotide sequence analysis identified 2 of the 3 cDNA fragments as encoding nucleophosmin (NPM) and T-plastin. The expression of NPM mRNA was induced after UV irradiation in UVr-10 cells but not in RSb cells, whereas irradiation did not affect the expression of T-plastin mRNA. UVr-10 cells transfected with antisense cDNA for NPM mRNA were partially sensitized to UV cell-killing. Thus, NPM and possibly T-plastin genes may contribute to the increased resistance to UV cell-killing, at least in the human cells tested.

Base Sequence↗

PubMed1998

Living-related liver transplantation and neurological outcome in children with fulminant hepatic failure.

BACKGROUND: Fulminant hepatic failure (FHF) in children is associated with high mortality under medical management. Living-related liver transplantation (LRLT) is an accepted measure to treat the children with end-stage liver disease. Reversibility of hepatic encephalopathy is crucial for the quality of life among the survivors after transplantation. METHODS: A retrospective review was made of the records of children undergoing LRLT at this hospital between May 1992 and November 1996. RESULTS: Eleven children with FHF underwent emergency LRLT. The mean age was 5 years (range, 2 months to 15 years). The indication for transplantation was persistent or worsening hepatic encephalopathy and severe coagulopathy, despite repeated plasma exchanges or exchange transfusions. The cause of FHF was non-A, non-B hepatitis in seven children, hepatitis B in two children, herpes simplex virus hepatitis in one child, and fulminant Wilson's disease with intravascular hemolysis in one child. The grade of hepatic encephalopathy was II in four children, III in two, and IV in five. The actuarial survival rate was 73% after a mean follow-up of 28 months (range, 13-67 months). Short-term neurological morbidity was present in two children with grade IV encephalopathy who also showed brain edema on cranial computed tomography. Eight survivors exhibited no long-term neurological deficit; the mean intelligence or developmental quotient was 97 (range, 86-110) at the end of the follow-up period. CONCLUSIONS: LRLT is an effective option for the treatment of FHF in children. The long-term neurological status is satisfactory among survivors.

Brain Edema↗

PubMed1998

Bone morphogenetic protein signaling is required for maintenance of differentiated phenotype, control of proliferation, and hypertrophy in chondrocytes.

To examine the role of bone morphogenetic protein (BMP) signaling in chondrocytes during endochondral ossification, the dominant negative (DN) forms of BMP receptors were introduced into immature and mature chondrocytes isolated from lower and upper portions of chick embryo sternum, respectively. We found that control sternal chondrocyte populations expressed type IA, IB, and II BMP receptors as well as BMP-4 and -7. Expression of a DN-type II BMP receptor (termed DN-BMPR-II) in immature lower sternal (LS) chondrocytes led to a loss of differentiated functions; compared with control cells, the DN-BMPR- II-expressing LS chondrocytes proliferated more rapidly, acquired a fibroblastic morphology, showed little expression of type II collagen and aggrecan genes, and upregulated type I collagen gene expression. Expression of DN-BMPR-II in mature hypertrophic upper sternal (US) chondrocytes caused similar effects. In addition, the DN-BMPR-II-expressing US cells exhibited little alkaline phosphatase activity and type X collagen gene expression, while the control US cells produced both alkaline phosphatase and type X collagen. Both DN-BMPR-II-expressing US and LS chondrocytes failed to respond to treatment with BMP-2 . When we examined the effects of DN forms of types IA and IB BMP receptors, we found that DN-BMPR-IA had little effect, while DN-BMPR-IB had similar but weaker effects compared with those of DN-BMPR-II. We conclude that BMP signaling, particularly that mediated by the type II BMP receptor, is required for maintenance of the differentiated phenotype, control of cell proliferation, and expression of hypertrophic phenotype.

Animals↗

PubMed1998

Increase in nitric oxide in the hypoxic-ischemic neonatal rat brain and suppression by 7-nitroindazole and aminoguanidine.

We measured the changes in nitric oxide (NO) metabolites in the brains of neonatal rats with hypoxic-ischemic damage. There were two peaks of NO metabolites in the lesioned side of the cortex without treatment: one during hypoxia and the other during the re-oxygenation period. Prehypoxic treatment with 7-nitroindazole, a selective neuronal NO synthase inhibitor, suppressed both peaks of NO metabolites, whereas prehypoxic treatment with aminoguanidine, a selective inducible NO synthase inhibitor, partially suppressed only the peak in the re-oxygenation period. These data suggest different roles of neuronal and inducible NO synthases in the pathogenesis of hypoxic-ischemic encephalopathy.

Animals↗

PubMed1998

Small spot sign of rectal carcinoma by endorectal ultrasonography: histologic relation and clinical impact on postoperative recurrence.

PURPOSE: We observed small spots at the margin of rectal carcinomas on endorectal ultrasonography. Our aim was to study the relationship between ultrasonographic evidence of these spots and histologic characteristics of disease and postoperative recurrence. PATIENTS AND METHODS: The study group comprised 55 patients, 36 men and 19 women, with rectal carcinoma as confirmed by biopsy. The patients were followed up at three-month intervals for six months to three years and six months after the operation. Endorectal ultrasonography was performed in the usual manner. Surgically resected specimens were stained with hematoxylin and eosin and histologically examined. Vessel invasion was graded from 0 (not invasive) to 3 (most invasive). RESULTS: Among the 55 patients studied, 3 had Stage T2,N0,M0 rectal carcinomas and 35 had Stage T3,N0,M0 carcinomas, 5 (14.3 percent) of whom had echographic evidence of small spots. Thirteen patients had Stage T3,N1/2,M0 carcinomas, comprising 12 (92.3 percent) with small spots, and four patients had T3,N1/2,M1 carcinomas, all with small spots. Vessel invasion of Grade 2 or higher was observed around the carcinomas in 20 of 21 patients who had small spots. Ten of 13 patients with many spots at the margin of the carcinoma (a spot grade of ++) histologically had marked venous or lymphatic invasion (an invasion Grade 3). The presence of small spots was closely associated with massive venous or lymphatic invasion (a vessel invasion grade of 2 or more). Four patients had synchronous liver metastases, and small spots were found in all four. Distant metastases and local recurrence were found in 11 of 21 patients with small spots. We found no recurrence in any patient without small spots on endorectal ultrasonography. CONCLUSIONS: Small spots indicate the presence of massive venous or lymphatic invasion and a high risk of postoperative recurrence.

Aged↗

PubMed1998

Limitation of endorectal ultrasonography: what does a low lesion more than 5 mm in size correspond to histologically?

PURPOSE: The accuracy of diagnosis of metastatic lymph nodes for rectal carcinoma has not improved. A low echoic lesion more than 5 mm in size detected by endorectal ultrasonography is preoperatively assessed as a metastatic lymph node. What does a low echoic lesion more than 5 mm in size correspond to histologically? METHODS: Forty-seven patients with lower rectal carcinoma (Term I, 1986-1990) and 48 patients with lower rectal carcinoma (Term II, 1991-1995) undergoing endorectal ultrasonography were reviewed. Surgically resected rectal specimens from 40 patients with rectal carcinoma underwent ultrasonography. Low echoic lesions more than 5 mm in size were taken from resected specimens and were stained with hematoxylin, followed by histologic examination. RESULTS: The accuracy of diagnosis of metastatic lymph nodes of Term II was not higher than that of Term I. Twenty-five low echoic lesions were detected by ultrasonography using 40 resected specimens. Seventeen of these 25 lesions (68 percent) were histologically confirmed to be metastatic lymph nodes. One of 25 (4 percent) was found to be lymphadenitis with no metastasis. Among the 25 lesions, 5 (20 percent) were histologically confirmed to be tumor deposits, 2 (8 percent) fatty tissue, and 22 (88 percent) carcinoma. CONCLUSIONS: Low echoic lesions were histologically confirmed to be tumor deposits (20 percent) and metastatic lymph nodes (68 percent). Although these data show deficiencies and limitations of the accuracy of endorectal ultrasonography, they compare favorably with other series, and no other current technology can show similar accuracy.

Endosonography↗

PubMed1998

Role of p53 and p21/WAF1 detection in patient selection for preoperative radiotherapy in rectal cancer patients.

BACKGROUND: Recent studies showed that p53 and p21 may play major roles in determining tumor radiosensitivity through the apoptosis pathway. The aim of this study was to investigate the predicting value of radiosensitivity in human rectal carcinoma. METHODS: p53 and p21/WAF1 expressions in formalin fixed, paraffin-embedded, preradiation biopsy samples from 49 patients with primary rectal carcinoma were analyzed immunohistochemically. p53 and p21 expressions and their relationships with histopathologic changes after radiation and other clinical features were evaluated. RESULTS: Expressions of p53 and p21/WAF1 were 49 and 28.6 percent, respectively. In 36.7 percent of total tumors, significant histopathologic effect can be observed. There was a significant inverse expression of p53 and p21. Most of the p53(+) or p21(-) tumors were radioresistant, and the majority of p53(-) or p21(+) tumors were radiosensitive. Tumors size in the radiosensitive, p53(-), or p21(+) group decreased more significantly than in radioresistant, p53(+), or p21(-) group (P < 0.01), and patients with radioresistant, p53(+), or p21(-) tumors had more local recurrence, more distant metastasis, and a shorter five-year survival rate than those with radiosensitive, p53(-), or p21(+) tumors, but without statistic significance. No statistically significant correlation can be observed between other tumor clinical features and radiosensitivity, p53, or p21 expressions. CONCLUSION: Immunohistochemistry detection of p53 and p21 expressions may be useful parameters for more radiosensitive patients selected for preoperative radiotherapy.

Adult↗

PubMed1998

Steroid complications and surgery in intractable ulcerative colitis.

The major operative indication for ulcerative colitis is intractability. Although steroid side effects appear to be closely associated with surgical indications for intractable ulcerative colitis, this relationship has yet to be analyzed in detail. To elucidate this relationship, we investigated 39 surgical patients with intractable ulcerative colitis, as defined by the Research Committee for Intractable Diseases of the Ministry of Health and welfare of Japan, and 66 conservatively treated patients with ulcerative colitis, of whom 6 had intractable disease. All patients with major steroid side effects and 17/24 (71%) patients with minor side effects underwent surgery. The median number of admissions was higher in patients with major side effects than in those with less severe or no side effects in the operative series, while this value was lower in the non-operative series than in the operative series. This tendency was similar for the total duration of hospitalization and the number of relapses. In the operative series, markedly higher steroid doses were administered to patients with side effects than to those without, and lower doses were given in the non-operative series. On multivariate regression analysis, the presence of steroid side effects, disease extent, and disease duration were significantly associated with surgery. Patients without side effects had a higher postoperative complication rate than those with minor side effects. We conclude that major side effects are a surgical indication for patients with intractable ulcerative colitis, and that even minor side effects should be taken as a surgical indication in view of the patient's quality of life.

Adolescent↗

PubMed1998

Functional magnetic resonance imaging during recognition of written words: Chinese characters for concrete objects versus abstract concepts.

An attempt was made to apply functional magnetic resonance imaging (fMRI) to reveal cortical areas activated upon presentation of two groups of Chinese characters in six normal right-handed, male, Japanese subjects. Presentation of the characters representing 'abstract concepts' activated the bilateral occipital region without a significant difference between the bilateral occipital and temporal regions. Presentation of the characters representing 'concrete objects' resulted in significantly stronger activation in the left occipital and temporal regions. These results suggest that recognition of concrete characters involves a stronger initial process in the left occipital temporal cortices than recognition of abstract characters.

Adult↗

PubMed1998

Functional magnetic resonance imaging during recognition of written words: Chinese characters for concrete objects versus abstract concepts.

Adult↗

PubMed1998

Phenotypic differences between T-->C and T-->G mutations at nt 8993 of mitochondrial DNA in Leigh syndrome.

This study reports on a patient with Leigh syndrome with a T-to-C mutation at nucleotide 8993 of mitochondrial deoxyribonucleic acid (T8993C). The authors reviewed 10 Leigh syndrome patients, including ours, with T8993C. Compared with 18 reported patients with Leigh syndrome caused by a T-to-G mutation at nucleotide 8993 (T8993G), Leigh syndrome with T8993C was characterized by a significantly higher frequency of ataxia (P < 0.01). None of the reviewed T8993C-associated Leigh syndrome patients had retinitis pigmentosa, which is one of the characteristic findings in Leigh syndrome with T8993G. The milder symptoms of T8993C-Leigh syndrome can be explained by the milder complex V dysfunction; however, the higher frequency of ataxia in T8993C-Leigh syndrome requires more study.

Child, Preschool↗

PubMed1998

Active oxygen-mediated chromosomal 1-2 Mbp giant DNA fragmentation into internucleosomal DNA fragmentation in apoptosis of glioma cells induced by glutamate.

C6 glioma cells treated with 10 mM glutamate reduced intracellular GSH to one-seventh of the initial level, and induced cytolysis accompanied by apoptosis. The treated cells produced extracellular H2O2. The cytolysis of the C6 cells induced by glutamate was prevented by antioxidants such as N-acetylcysteine (NAC), ascorbic acid (ASC), catalase, and NaN3, iron chelators such as deferoxamine and 1,10-phenanthroline, and oxygen radical scavengers such as 5,5'-dimethyl-1-pyrroline-N-oxide (DMPO) and alpha-phenyl-tert-butyl nitrone (PBN). The effect of these antioxidants, iron chelators, and oxygen radical scavengers on the cytolysis of C6 cells was dependent on the dose and the intracellular GSH level. Furthermore, 1-2 Mbp chromosomal DNA (giant DNA) fragments were observed during cytolysis. The giant DNA fragments were further cleaved into smaller DNA fragments of 200-800 kbp, and then to fragments of less than 300 kbp in size including chromosomal ladder DNA fragments. Such serial chromosomal DNA degradations induced by glutamate were also inhibited by addition of these antioxidants, iron chelators, and oxygen radical scavengers. These findings suggest that glutamate induces GSH depletion, and consequently, apoptosis through endogenously produced active oxygen species in C6 glioma cells and that the apoptosis is accompanied by 1-2 Mbp giant DNA fragmentation prior to the internucleosomal DNA fragmentation.

Acetylcysteine↗

PubMed1998

Enhancement of XPG mRNA expression by human interferon-beta in Cockayne syndrome cells.

Using PCR-differential display, we have searched for genes expressed specially in human interferon (HuIFn)-beta-treated Cockayne syndrome (CS) fibroblast cells. Eighteen expressed genes induced by HuIFN-beta were identified, the sequences of seven of which were highly homologous to previously cloned sequences. The cDNAs of six of these seven clones were similar to expression tagged sequences from unknown genes in databases and the remaining one was identical to the cDNA of the xeroderma pigmentosum XPG gene. These results, together with our previous finding of increased resistance to ultraviolet (UV) cell-killing of CS cells pretreated with HuIFN-beta prior to UV irradiation suggest that XPG might be one of the genes possibly involved in the HuIFN-beta-induced UV-resistance.

Cells, Cultured↗

PubMed1998

Syntheses and preventive effects of analogues related to 1alpha,25-dihydroxy-2beta-(3-hydroxypropoxy)vitamin D3 (ED-71) on bone mineral loss in ovariectomized rats.

Analogues related to 1alpha,25-dihydroxy-2beta-(3-hydroxypropoxy)vitamin D3 (ED-71) (2), 26,27-dimethyl ED-71 (3) and 26,27-diethyl ED-71 (4), were synthesized from lithocholic acid (5). In the study of the preventive effects of these analogues and ED-71 (2) on bone mineral loss in ovariectomized rats, 26,27-dimethyl ED-71 (3) showed the most potent activity.

Animals↗

PubMed1998

Computed tomographic features of calcifying odontogenic cysts.

OBJECTIVES: To describe the CT appearances of 4 cases of the calcifying odontogenic cyst (COC) with particular reference to the effect of varying the window settings. METHODS: Conventional radiographs and CT scans of 4 calcifying odontogenic cysts were analyzed with respect to the presence of an impacted tooth, root resorption and calcification. In addition, increased attenuation by desquamated keratin was examined by varying the window settings on CT. RESULTS: All lesions were located in the maxilla and on conventional radiographs, had unilocular radiolucency with a well-defined margin. Calcifications and inclusion of an impacted tooth were seen in all cases. Root resorption was observed in two cases, but was not prominent. On CT, calcification was detected at the periphery of the lesion and/or around the impacted tooth in all cases. Varying the window setting revealed an increased attenuation area due to desquamated keratin. CONCLUSIONS: Varying the window setting on CT is useful as a means of identifying both desquamated keratin and peripheral calcification in COC.

Adolescent↗