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K Okuyama

Publications and source records attributed to K Okuyama.

At least 55 records · Page 3Linked to original sources
PubMed1999

Structural study of anhydrous tendon chitosan obtained via chitosan/acetic acid complex.

The molecular structure and packing arrangement of anhydrous tendon chitosan was determined by the X-ray fibre diffraction method together with the linked-atom least-squares refinement technique. The specimen was prepared from chitosan/acetic acid complex which was obtained by exposing tendon chitosan to acetic acid vapour at room temperature for several days. There is high degree of orientation and crystallinity compared with the specimen obtained by the annealing method. Two chitosan chains are present in an orthorhombic unit cell of dimensions a = 8.26(2), b = 8.50(1), c (fibre axis) = 10.43(2) A and space group P2(1)2(1)2(1). The 2-fold helical chain is stabilised by O3 triple bond O5 hydrogen bond with the gt orientation of O6. There are direct hydrogen bonds (N2 triple bond O6) between adjacent chains along the a-axis, which makes a sheet structure parallel to the ac-plane. On the other hand, no hydrogen bond is found between the sheets.

Acetic Acid↗
PubMed1999

Recent trends in the prevalence of Down syndrome in Japan, 1980-1997.

The aims of the present study were to determine recent trends in the prevalence of Down syndrome (DS) in Japan, and to determine whether recent changes in demographic and social habits and access to prenatal diagnosis have influenced the livebirth rates of DS. Livebirth statistics indicate that the birth rate in Japan has decreased for women in their 20s and has increased for those in their 30s and 40s. During an 18-year period between 1980 and 1997, 1,299 consecutive DS infants were born among a total of 2,232,694 births, a rate corresponding to approximately 10% of all births in Japan over the same period. The increasing risk of DS with advancing maternal age was confirmed. The overall prevalence was 5.82 DS births per 10,000 livebirths (8.3-9.7 per 10,000 after correction according to the estimated ascertainment ratio: 60-70%). The prevalence rate by year of child birth represents a statistically significant increase (P = 0.001). In conclusion, recent trends in the prevalence of DS in Japan from 1980 to 1997 failed to show a consistent tendency to decrease, probably because of the concomitant increase in pregnancy in advanced maternal age.

Birth Rate↗
PubMed1999

Crystal structure of Thermoactinomyces vulgaris R-47 alpha-amylase II (TVAII) hydrolyzing cyclodextrins and pullulan at 2.6 A resolution.

The crystal structure of Thermoactinomyces vulgaris R-47 alpha-Amylase II (TVAII) has been determined by multiple isomorphous replacement at 2.6 A resolution. TVAII was crystallized in an orthorhombic system with the space group P212121 and the cell dimensions a=118.5 A, b=119.5 A, c=114.5 A. There are two molecules in an asymmetric unit, related by the non-crystallographic 2-fold symmetry. Diffraction data were collected at 113 K and the cell dimensions reduced to a=114.6 A, b=117.9 A, c=114.2 A, and the model was refined against 7.0-2.6 A resolution data giving an R-factor of 0.204 (Rfree=0.272). The final model consists of 1170 amino acid residues (two molecules) and 478 water molecules with good chemical geometry. TVAII has three domains, A, B, and C, like other alpha-amylases. Domain A with a (beta/alpha)8 barrel structure and domain C with a beta-sandwich structure are very similar to those found in other alpha-amylases. Additionally, TVAII has an extra domain N composed of 121 amino acid residues at the N-terminal site, which has a beta-barrel-like structure consisting of seven antiparallel beta-strands. Domain N is one of the driving forces in the formation of the dimer structure of TVAII, but its role in the enzyme activity is still not clear. TVAII does not have the Ca2+ binding site that connects domains A and B in other alpha-amylases, rather the NZ atom of Lys299 of TVAII serves as the connector between these domains. TVAII can hydrolyze cyclodextrins and pullulan as well as starch. Based on a structural comparison with the complex between a mutant cyclodextrin glucanotransferase and a beta-cyclodextrin derivative, Phe286 located at domain B is considered the residue most likely to recognize the hydrophobic cavity of cyclodextrins. The active-site cleft of TVAII is wider and shallower than that of other alpha-amylases, and seems to be suitable for the binding of pullulan which is expected not to adopt the helical structure of amylose.

Bacillus↗
PubMed1999

Crystal structure of the E166A mutant of extended-spectrum beta-lactamase Toho-1 at 1.8 A resolution.

Bacterial resistance to beta-lactams is mainly due to the production of beta-lactamase. Especially through the production of extended-spectrum beta-lactamases (ESBLs), bacteria have acquired resistance not only to penicillins, but also to expanded-spectrum cephems. Here, we describe the crystal structure of the E166A mutant of class A beta-lactamase Toho-1 at 1.8 A resolution, the first reported tertiary structure of an ESBL. Instead of the wild-type enzyme, a mutant Toho-1, in which Glu166 was replaced with alanine, was used for this study, because of the strong tendency of the wild-type enzyme to form twinned crystals. The overall structure of Toho-1 is similar to the crystal structures of non-ESBLs, with no pronounced backbone rearrangement of the framework. However, there are some notable local changes. First, a difference in the disposition of an arginine residue, which is at position 244 in non-ESBLs but at position 276 in Toho-1 and other ESBLs, was revealed and the role of this arginine residue is discussed. Moreover, changes in the hydrogen-bonding pattern and in the formation of the hydrophobic core were also observed near the Omega loop. In particular, the lack of hydrogen bonds in the vicinity of the Omega loop could be a cause of the extended substrate specificity of Toho-1. Through the generation of a model for the enzyme-substrate complex, a conformational change of Toho-1 occurring on complex formation is discussed based on the active-site cleft structure and the substrate profile.

Amino Acid Sequence↗
PubMed1999

Primary Non-Hodgkin's Lymphoma of the Male Breast: A Case Report.

A 69-year-old Japanese man presented with bilateral gynecomastia and a soft, mobile and clearly defined mass beneath the left nipple. A round radiopaque masswas revealed on mammography. The tumor was homogeneous, hypoechoic and measured2.4 x 3.9 cm on ultrasonography. Based on a diagnosis of malignant lymphoma by needle aspiration cytology, a modified radical mastectomy with ipsilateral axillary lymph node dissection was performed. Malignant diffuse large B-cell type lymphoma was diagnosed histologically. Whole body examinations revealed no evidenceof other tumors. Three courses of adjuvant CHOP therapy were subsequently performed. The patient is free of recurrence 12 months after surgery. Primary non-Hodgkin's lymphoma (NHL) of the male breast is extremely rare. The occurrence of lymphoma in this patient could be related to elevated estrogen levels.

Journal Article↗
PubMed1999

Induction of antenatal periventricular leukomalacia by hemorrhagic hypotension in the chronically instrumented fetal sheep.

OBJECTIVES: Our purpose was to determine whether systemic hypotension induced by rapid withdrawal of fetal blood would induce periventricular leukomalacia in the brain of premature fetal sheep. STUDY DESIGN: At 113 days' gestation, systemic hypotension (mean blood pressure <30 mm Hg) was induced by withdrawing approximately 35% of the fetoplacental blood volume in the hemorrhage group (n = 6), whereas in the control group (n = 4) isovolemic exchange transfusion was carried out. Six days after the insult, fetal brains were removed and processed for histologic analysis. RESULTS: Five of the 6 fetuses in the hemorrhage group exhibited periventricular white-matter lesions, consisting of nodular coagulation necrosis or diffuse axonal swellings or both. No abnormal findings other than these lesions were detected in the fetal brains in either experimental group. CONCLUSION: Hemorrhagic hypotension antenatally induced brain lesions similar to those of periventricular leukomalacia, suggesting that it is an essential element in the pathogenesis of periventricular leukomalacia in premature fetuses.

Animals↗
PubMed1999

Estimated nutritional intake based on the reference growth curves for extremely low birthweight infants.

BACKGROUND: Although the optimal goal of extremely low birthweight (ELBW) infants has been debated, it can be argued that the best nutritional strategy for ELBW infants is one which achieves better growth while preventing neurological sequelae due to nutritional inadequacy, even if it does not mimic fetal growth. Our aim is to propose an advisable and practically feasible nutritional intake for ELBW infants. METHODS: We retrospectively investigated the nutritional intake in 16 ELBW infants (gestational age 26.7 weeks, birthweight 879.6 g), who exceeded the standard growth curves for Japanese infants of ELBW. We also analyzed the nutritional composition of human milk from 15 mothers delivering before term (PT milk) until the 12th week of lactation. The nutritional intake was calculated according to the composition of the parenteral and enteral regimen. RESULTS: The infants tolerated more than 100 mL/kg per day of milk until the fourth week of life. An average weight gain of more than 15 g/kg per day was achieved by the sixth week. An advisable nutritional intake capable of sustaining ELBW infants in a stable growing phase was calculated as the sum of the mean plus 1SD of the daily nutritional intake. CONCLUSIONS: To exceed the ordinary growth curves for ELBW Japanese infants, it was suggested that more than 100 mL milk/kg per day could be fed until the fourth week of life, while the advisable daily intake of nutrients after six weeks of life should be as follows: water 160 mL/kg, protein 3.2 g/kg, fat 7.4 g/kg, carbohydrate 12.8 g/kg, energy 544 kJ/kg, the following minerals in mg/kg: sodium 45, chloride 82, potassium 110, calcium 140, phosphorus 70, magnesium 11, zinc 0.5 and copper at 60 micrograms/kg. Further studies will be needed to confirm the safety and effectiveness of this advisable intake for ELBW infants.

Birth Weight↗
PubMed1999

Structure analysis of a collagen-model peptide with a (Pro-Hyp-Gly) sequence repeat.

The crystal structure of a triple helical peptide (Pro-Hyp-Gly)10 has been determined at 1.9 A resolution. Single crystals grown by the hanging drop method, diffracted to a resolution of 1.8 A. The polymer-like structure of the triple helical repeat Pro-Hyp-Gly was in accordance with the 7/2 model proposed for collagen and very similar to the previously determined structure with a Pro-Pro-Gly sequence repeat. The solvent structure was also very similar to that previously observed, showing similar hydration patterns, but different crystal packing. The presence of hydroxyproline did not have any effect on the molecular structure or the hydration structure. This is in accordance with the recent finding that the inductive effect of the hydroxyl group attached to the Cgamma atom of hydroxyproline enhances collagen stability rather than the extensive water network.

Collagen↗
PubMed1999

Morphological aspects of ectopia cordis: four case reports and a review of the literature.

Ectopia cordis is a rare congenital anomaly. We present 4 cases of ectopia cordis, 1 of which is the first report of an affected fetus in a triplet pregnancy. The morphological relationship between the types of ectopia cordis and their outcomes were investigated in all 4 cases. In addition, the literature on ectopia cordis in Japan was reviewed and discussed.

Adult↗
PubMed1999

A novel Na+ and Ca2+ channel blocker, T-477, prevents brain edema following microsphere-induced permanent occlusion of cerebral arterioles in rats.

One of the most common acute complications of stroke is brain edema. Treatment of edema is recommended when the condition of the patients is deteriorating. The present study was undertaken to evaluate the effect of T-477 [(R)-(+)-2-(4-chlorophenyl)-2,3-dihydro-4-diethyl aminoacetyl-4H-1,4-benzorthiazine hydrochloride], a novel neuronal Na+ and Ca2+ channel blocker, on brain edema in rats. Cerebral ischemia was induced by intra-arterial infusion of 1000 microspheres into the forebrain of freely moving rats, resulting in brain edema. T-477 was intravenously infused continuously for 24 h or twice for 3 h with a 3-h interval between infusions immediately after microsphere injection. T-477 dose-dependently inhibited the increase in brain water content by both infusion procedures; the inhibition was statistically significant at doses of 25 mg/kg per 24 h and 14 mg/kg per 9 h. Additionally, infusion of T-477 at a dose of 14 mg/kg per 9 h significantly inhibited the decrease in K content and the increase in Ca content of the forebrain. In conclusion, T-477 prevents brain edema following microsphere-induced cerebral embolism in rats.

Animals↗
PubMed1999

Posterior lumbar interbody fusion: a retrospective study of complications after facet joint excision and pedicle screw fixation in 148 cases.

We retrospectively evaluated neurological and other complications related to posterior lumbar interbody fusion (PLIF) performed by facet joint excision and pedicle screw fixation, in 148 consecutive patients with degenerative disorders. Their mean age at surgery was 59 (19-80) years. The mean follow-up period was 3 (2-6.5) years. Overall, 91 complications in 75 cases were observed. Although no permanent neural damage was detected, transient neural palsy occurred in 8% of the cases. Dural tear, partial misplacement, loosening, breakage of the pedicle screw and loss of correction were seen in 6, 6, 4, 1 and 1 of the cases, respectively. Deep infection of the fused segment developed in 2 cases. We conclude that PLIF, performed by facet joint excision and pedicle screw fixation, demonstrated a very low incidence of osteosynthesis failure, such as screw loosening, breakage and loss of correction. However, the high incidence of other complications, particularly neurological impairment, is still a disadvantage of this technically-demanding procedure.

Adult↗
PubMed1999

Purification of recombinant human serum albumin efficient purification using STREAMLINE.

Two inter-related challenges must be overcome to develop a recombinant human serum albumin process. One is purity; the other is cost. Regarding cost, our goal is to produce recombinant human serum albumin at least as economically as plasma derived human serum albumin. To control production costs, maximum quantities of albumin must be produced from minimum volumes of cell culture, followed by high efficiency, high-yield purification methods. By introducing STREAMLINE technology, we have improved productivity by roughly 50% in terms of processing time and 45% in terms of yield. Furthermore, the life time of the gel and column are very long. After more than 1000 process cycles, performance remained unchanged.

Chromatography, Liquid↗
PubMed1998

Crystal structure analysis of collagen model peptide (Pro-pro-Gly)10.

Single crystals of (Pro-Pro-Gly)10 were grown by the hanging drop method. The crystals diffracted to a resolution of 1.8 A. In the crystals the polypeptides form triple helices that aggregate end-to-end mediated by the solvent molecules, with the basic repeat being 20 A along the helical axis. Analysis of the 20 A structure of (Pro-Pro-Gly)10 using data up to a resolution of 1.9 A revealed that the overall structure is in accordance with the 7/2 model proposed for collagen. The three strands are held together by the (Gly) N-H O (Pro-X) hydrogen bond interactions, and additional stability is provided by the (Pro-Y) Calpha -H O (Pro-X) hydrogen bonding interactions.

Collagen↗
PubMed1998

Distribution pattern and risk factors of pelvic and para-aortic lymph node metastasis in epithelial ovarian carcinoma.

The distribution of lymph node metastasis and the clinicopathologic risk factors for nodal involvement in ovarian carcinoma need to be clarified based on systematic lymph node dissection. We studied 115 patients with ovarian carcinoma who underwent systematic pelvic and para-aortic lymph node dissection between 1987 and 1997. The incidence and distribution of lymph node metastasis are described and the clinico-pathologic risk factors for nodal involvement are investigated. Based on the occurrence of lymph node metastasis in the early stages, the incidence of solitary node involvement and the distribution of lymph node metastasis, we conclude that the primary site of nodal involvement in ovarian carcinoma is the para-aortic node (PAN), especially PAN superior to the inferior mesenteric artery (IMA). By univariate analysis, clinical stage, histologic type (mucinous vs. others), grade, multiple peritoneal metastases, peritoneal cytology, volume of ascites and serum CA125 level were correlated with overall incidence of lymph node metastasis. By performing a multivariate analysis with the clinical stage excluded, it was revealed that grade and peritoneal cytology were independent factors for PAN metastasis (p < 0.0025 and < 0.001, respectively) and that multiple peritoneal metastases and PAN metastasis were significant predictors of pelvic node metastasis (p < 0.01 and < 0.005, respectively). In conclusion, the PANs superior and inferior to IMA should be explored in staging of ovarian carcinoma that appears to be confined to the ovaries. To determine accurately the extent of disease, both the para-aortic and pelvic areas may need to be sampled or dissected in the case of ovarian carcinoma involving the peritoneal surfaces.

Adenocarcinoma, Clear Cell↗
PubMed1998

Prenatal identification of mos 45,X/46,X,+mar in a normal male baby by cytogenetic and molecular analysis.

We report a case of mos 45,X/46,X,+mar, diagnosed prenatally by amniocentesis, whose physical examination, including external and internal organs, along with serum testosterone values were normal five years after delivery. The mosaic karyotype was seen in 146 of 240 cells examined (amniotic fluid cells, 110/65; placental chorionic villi: 5/4; cord blood, 21/81; cultured skin fibroblasts, 10/90) from 386 metaphases, and the marker chromosome appeared as a small non-fluorescent acrocentric chromosome. All autosomes appeared normal, and no normal Y chromosome could be demonstrated. Analysis of 26 Y-chromosome loci by molecular techniques such as PCR, Southern analysis using multiple Y-specific DNA probes, and Hae III restriction endonuclease assessment of male-specific repeated DNA in the heterochromatic region of the Y chromosome, and fluorescence in situ hybridization (FISH), revealed the marker was derived from a Y chromosome including p terminal to q11.23, and paracentric inversion in the remaining Y long arm. The formation of testes can be considered as existence of SRY (sex-determining region of Y) as a testis-determining factor. The present report illustrates the importance of FISH and molecular techniques as a complement to cytogenetic methods for accurate identification and characterization of chromosome rearrangements in prenatal diagnosis.

Adult↗
PubMed1998

A selective inhibitor of intestinal ACAT, EAB309 suppresses both intestinal and hepatic cholesterol output and stimulates chylomicron removal.

The effect of a novel inhibitor of acylcoenzyme A:cholesterol acyltransferase (EC 2.3.1.26, ACAT), EAB309 (EAB) on plasma lipid metabolism was studied in cholesterol-fed rats. Orally administered EAB was not detected in the portal vein or the liver but distributed exclusively in the intestine, suggesting that this agent selectively inhibits intestinal ACAT. The rats were fed with either a cholesterol-diet or a cholesterol-diet containing 0.005% EAB (w/w) ad. libium for three weeks. ACAT activity in intestinal microsomes was significantly inhibited in EAB-treated rats. Hepatic ACAT activity was also decreased in EAB-treated rats, however, this was attenuated by the addition of excess cholesterol to the liver microsome, indicating that substrate availability is tightly associated with this enzyme's activity and the inhibition of hepatic ACAT by EAB is not direct. Incorporation of [3H]-cholesterol to cholesteryl ester (CE) in mesenteric lymph were markedly suppressed by EAB treatment. Chylomicrons (CMs) were doubly labeled with [3H]-vitamin A and [14C]-triglyceride (TG) in EAB-treated or non-treated rats and injected into normal chow-fed rats. The CMs from EAB-treated rats were cleared faster from the plasma and taken up more by the liver compared with the CMs from non-treated rats. The content of CE in newly secreted VLDL was remarkably decreased by EAB treatment without affecting TG output. These results demonstrate that EAB, a novel inhibitor of intestinal ACAT, significantly suppresses both intestinal and hepatic CE output and stimulates CM removal. This suggests that the inhibition of intestinal ACAT can subsequently suppress hepatic ACAT by decreased CE delivery from the intestine to the liver.

Animals↗
PubMed1998

Alcohol-related cancers and aldehyde dehydrogenase-2 in Japanese alcoholics.

Aldehyde dehydrogenase-2 (ALDH2) eliminates most of the acetaldehyde produced during alcohol metabolism. In some drinkers, a mutant ALDH2 allele contributes to diminished activity of the enzyme, dramatically increasing the risk for esophageal cancer. This study was designed to evaluate the ALDH2 gene polymorphism as a predictor of the development of cancers prevalent in Japanese alcoholics. We performed ALDH2 genotyping on lymphocyte DNA samples from Japanese alcoholic men (487 cancer-free; 237 with cancer, including 34 oropharyngolaryngeal, 87 esophageal, 58 stomach, 46 colon, 18 liver, 7 lung, 9 other sites, and 19 multiple primary cancers in two or three organs). The frequencies of the mutant ALDH2*2 allele were significantly higher in alcoholics with oropharyngolaryngeal (52.9%), esophageal (52.9%), stomach (22.4%), colon (21.7%) and esophageal cancer concomitant with oropharyngolaryngeal and/or stomach cancer (78.6%), than in cancer-free alcoholics (9.0%). After adjustment for age, daily alcohol consumption and amount of cigarette smoking, significantly increased risks (odds ratios) in the presence of the ALDH2 *2 allele were found for oropharyngolaryngeal (11.14), esophageal (12.50), stomach (3.49), colon (3.35), lung (8.20) and esophageal cancer concomitant with oropharyngolaryngeal and/or stomach cancer (54.20) but not for liver or other cancers. These results suggest a general role of acetaldehyde, a recognized animal carcinogen, in the development of human cancers.

Adult↗