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H Ohtake

Publications and source records attributed to H Ohtake.

At least 37 records · Page 2Linked to original sources
PubMed2000

A highly stereoselective construction of beta-glycosyl linkages by reductive cleavage of cyclic sugar ortho esters.

The preparation of beta-glycosides by the reductive cleavage of spiro sugar ortho esters is described in this report. This procedure is based on a concept completely different from those of other methods for glycosylation. Twelve sugar ortho esters that commonly possess perhydrospiro[2H-pyran-2,2'-pyrano[3,2-d][1,3]dioxin] ring systems in their molecules were reduced by LiAlH(4)/AlCl(3) or NaCNBH(3)/AlCl(3). Among these ortho esters, those (9a-12a) prepared from the D-sugar lactones (1-4) and 2, 3-di-O-benzyl-alpha-D-glucopyranoside (7) or those (19a, 20a) prepared from the L-sugar lactones (5, 6) and 2, 3-di-O-benzyl-alpha-D-galactopyranoside (8) were selectively converted into beta-(1 --> 4)-glycosides (9b-12b or 19b, 20b) in excellent yields by the treatment of LiAlH(4)/AlCl(3). In contrast, the ortho esters (13a-16a or 17a, 18a) that were prepared from combinations of the D-sugar lactones and 8 or those of the L-sugar lactones and 7 were efficiently reduced with NaBH(3)CN/AlCl(3) to afford beta-(1 --> 6)-glycosides (13b-16b or 17b, 18b) selectively. It was remarkable that the resulting disaccharides were obtained with extremely high beta-selectivity even in the cases with mannosyl or rhamnosyl glycosides. Moreover, these products would be useful units for the construction of branched saccharides, because the newly formed hydroxy groups could be again glycosylated without further deprotection procedures. The high regio- and stereoselectivity was totally explained by considering the structures and the conformations of these ortho ester molecules and the stereoelectoronic effects of their spiro ring systems. In addition, the preparation of the sugar ortho esters with glucosamine derivatives and the reactivity of these ortho esters are described in this report. N-Phthaloyl glucosamine derivatives (21, 22) were efficiently reacted with the benzyl-protected gluconolactone (1) in the presence of TMSOMe and TMSOTf to afford ortho esters (23a-c). After the conversion of the phthalimido functionality to the dibenzyl amino group, glucosylideneglucosamine (25) was reduced with LiAlH(4)/AlCl(3) to afford beta-(1 --> 4)-glycoside (26) selectively.

Aluminum Chloride↗
PubMed2000

Laparoscopic diagnosis and clinical course of chronic schistosomiasis japonica.

Laparoscopic findings of nine patients with chronic schistosomiasis japonica were analyzed and compared to hepatic ultrasonograms, computed tomography (CT) scans and histological findings from the same patients. In all nine patients laparoscopy revealed yellowish, small speckles, approximately 50 microm in diameter, sparse or clustered over the liver surface, which were later found to represent subcapsular calcified ova of Schistosoma japonicum. While the liver surface was almost smooth in mild schistosomiasis, multiple whitish markings and irregular, relatively wide, groove-like septums were seen in more advanced cases. In severe schistosomiasis block-like formations of variable size, separated by groove-like depressions, made the liver surface appear like a tortoise shell. In moderate or severe schistosomiasis ultrasonography revealed spotted high echoes and CT scans demonstrated network patterns and lineal calcified spots. The liver surface of chronic schistosomiasis japonica without re-infection appeared stable without change over time but with a tendency to improve. Hepatocellular carcinoma was initially recorded in two of the nine patients and follow-up revealed a further two with the same diagnosis. However, all these four cases also had chronic hepatitis C (HCV). Hepatocellular carcinoma was not detected in patients without viral hepatitis, indicating that hepatic viral infection is more important than schistosomiasis in promoting the development of hepatocellular carcinoma.

Aged↗
PubMed2000

Facile ring transformation from gluconolactone to cyclitol derivative via spiro sugar ortho ester.

[reaction: see text] A short step preparation of cyclitol derivative 8 which is a versatile synthon for the synthesis of valiolamine and its related compounds is described. Key steps in this preparation are a novel enol ether formation from spiro sugar ortho esters with AlMe3 and an intramolecular Aldol condensation of alkyl enol ethers catalyzed by ZnCl2 in THF-H2O. With these reactions, gluconolactone derivative 1 was efficiently converted into 8 in short steps.

Carbohydrates↗
PubMed2000

Retention of words in long-term memory: a functional neuroanatomical study with PET.

We used PET to identify brain regions associated with retention of verbal materials in long-term memory. During a PET scan, subjects repeated many sets of words one after another. In a retention condition, they were simultaneously required to retain 10 key words that were irrelevant to the repetition task. Significant increases in regional cerebral blood flow during the retention condition were found in bilateral parahippocampal regions, the left prefrontal and parietal association cortices, the supplementary motor area, the neostriatum and the cerebellum. We clearly demonstrated that retention of verbal materials was accompanied by neural activities in the medial temporal lobes. We also showed that, in the early phase, retention of words in long-term memory recruited left cortical areas surrounding those relevant to verbal short-term memory.

Acoustic Stimulation↗
PubMed2000

An immunohistochemical and ultrastructural study of a follicle-stimulating hormone-secreting gonadotroph adenoma occurring in a 10-year-old girl.

Female gonadotroph adenomas with endocrinological symptoms are uncommon. Six cases of such adenomas have been reported in the literature: two were girls who presented with precocious puberty and four were premenopausal women with accompanying multiple ovarian cysts. We describe here a 10-year-old Japanese girl with a gonadotroph macroadenoma and present detailed morphological findings of the tumor. The patient's chief complaints were nausea, abdominal distention, and abdominal pain. Abdominopelvic ultrasonography and magnetic resonance imaging (MRI) revealed bilateral multiple ovarian cysts. Endocrinological assays showed elevated serum follicle-stimulating hormone (FSH) (33.7 mIU/ml) and estradiol (3840 pg/ml). MRI of the head showed a large pituitary tumor. Two transsphenoidal operations and subsequent radiation therapy were performed. Immunohistochemically, more than half the tumor cells were positive for anti-FSH-beta monoclonal antibody. Ultrastructurally, the tumor cells exhibited a fairly uniform picture of rounded cells. Their nuclei were slightly irregular and contained heterochromatin, and their cytoplasm contained many round, dense core granules, measuring 140-260 nm in diameter, together with well-developed organelles. An in vitro study showed that the tumor cells in primary culture produced FSH (1089.0 mIU/ml). To our knowledge, this is the first immunohistochemical and ultrastructural study of an FSH-secreting gonadotroph adenoma occurring in childhood.

Adenoma↗
PubMed2000

Involvement of an extracellular protease in algicidal activity of the marine bacterium Pseudoalteromonas sp. strain A28.

The marine bacterium Pseudoalteromonas sp. strain A28 was able to kill the diatom Skeletonema costatum strain NIES-324. The culture supernatant of strain A28 showed potent algicidal activity when it was applied to a paper disk placed on a lawn of S. costatum NIES-324. The condensed supernatant, which was prepared by subjecting the A28 culture supernatant to ultrafiltration with a 10,000-M(w)-cutoff membrane, showed algicidal activity, suggesting that strain A28 produced extracellular substances capable of killing S. costatum cells. The condensed supernatant was then found to have protease and DNase activities. Two Pseudoalteromonas mutants lacking algicidal activity, designated NH1 and NH2, were selected after N-methyl-N'-nitrosoguanidine mutagenesis. The culture supernatants of NH1 and NH2 showed less than 15% of the protease activity detected with the parental strain, A28. The protease was purified to homogeneity from A28 culture supernatants by using ion-exchange chromatography followed by preparative gel electrophoresis. Paper-disk assays revealed that the purified protease had potent algicidal activity. The purified protease had a molecular mass for 50 kDa, and the N-terminal amino acid sequence was determined to be Ala-Thr-Pro-Asn-Asp-Pro. The optimum pH and temperature of the protease were found to be 8.8 and 30 degrees C, respectively, by using succinyl-Ala-Ala-Pro-Phe-p-nitroanilide as a substrate. The protease activity was strongly inhibited by phenylmethylsulfonyl fluoride, diisopropyl fluorophosphate, antipain, chymostatin, and leupeptin. No significant inhibition was detected with EDTA, EGTA, phenanthroline or tetraethylenepentamine. These results suggest that Pseudoalteromonas sp. strain A28 produced an extracellular serine protease which was responsible for the algicidal activity of this marine bacterium.

Amylases↗
PubMed2000

Identification and characterization of two chemotactic transducers for inorganic phosphate in Pseudomonas aeruginosa.

Two chemotactic transducers for inorganic phosphate (P(i)), designated CtpH and CtpL, have been identified in Pseudomonas aeruginosa. The corresponding genes (ctpH and ctpL) were inactivated by inserting kanamycin and tetracycline resistance gene cassettes into the wild-type genes in the P. aeruginosa PAO1 genome. Computer-assisted capillary assays showed that the ctpH single mutant failed to exhibit P(i) taxis when the concentration of P(i) in the capillary was higher than 5 mM. Conversely, the ctpL single mutant could not respond to P(i) at the concentration of 0.01 mM. The ctpH ctpL double mutant was defective in P(i) taxis at any concentration ranging from 0.01 to 10 mM. To investigate regulation of P(i) taxis, the ctpH and ctpL genes were also disrupted individually in the P. aeruginosa phoU and phoB single mutants. The ctpH phoU and ctpH phoB double mutants were defective in P(i) taxis, regardless of whether the cells were starved for P(i). The ctpL phoU double mutant was constitutive for P(i) taxis, whereas the ctpL phoB double mutant was induced by P(i) limitation for P(i) taxis. The region upstream of ctpL, but not ctpH, contained a putative pho box sequence. Expression of ctpL::lacZ was induced by P(i) limitation in PAO1, while it was constitutive in the phoU mutant. In contrast, the phoB mutant showed only background levels of ctpL::lacZ expression. These results showed that ctpL is involved in the pho regulon genes in P. aeruginosa. The ctpH phoU mutant, which failed to exhibit P(i) taxis, was constitutive for ctpL::lacZ expression, suggesting that the P(i) detection by CtpL requires PhoU. Like PAO1, the phoB and phoU single mutants were constitutive for expression of ctpH::lacZ. Thus, the evidence that the ctpL phoU mutant, but not the ctpL phoB mutant and PAO1, was constitutive for P(i) taxis raised the possibility that PhoU exerts a negative control on P(i) detection by CtpH at the posttranscriptional level.

Bacterial Proteins↗
PubMed2000

Physical map location of the multicopy genes coding for ammonia monooxygenase and hydroxylamine oxidoreductase in the ammonia-oxidizing bacterium Nitrosomonas sp. strain ENI-11.

Pulsed-field gel electrophoresis of PmeI digests of the Nitrosomonas sp. strain ENI-11 chromosome produced four bands ranging from 1,200 to 480 kb in size. Southern hybridizations suggested that a 487-kb PmeI fragment contained two copies of the amoCAB genes, coding for ammonia monooxygenase (designated amoCAB(1) and amoCAB(2)), and three copies of the hao gene, coding for hydroxylamine oxidoreductase (hao(1), hao(2), and hao(3)). In this DNA fragment, amoCAB(1) and amoCAB(2) were about 390 kb apart, while hao(1), hao(2), and hao(3) were separated by at least about 100 kb from each other. Interestingly, hao(1) and hao(2) were located relatively close to amoCAB(1) and amoCAB(2), respectively. DNA sequence analysis revealed that hao(1) and hao(2) shared 160 identical nucleotides immediately upstream of each translation initiation codon. However, hao(3) showed only 30% nucleotide identity in the 160-bp corresponding region.

Chromosome Mapping↗
PubMed2000

Dynamic contrast-enhanced MR imaging of uterine cervical cancer: pharmacokinetic analysis with histopathologic correlation and its importance in predicting the outcome of radiation therapy.

PURPOSE: To investigate the histopathologic bases of different enhancement patterns on dynamic contrast material-enhanced magnetic resonance (MR) images of cervical cancer and to assess their importance in predicting the outcome of patients after radiation therapy. MATERIALS AND METHODS: Dynamic enhanced MR imaging and pharmacokinetic analyses were performed in 26 patients with cervical cancer who subsequently underwent hysterectomy and in 36 patients with cervical cancer who received radiation therapy. Histopathologic findings and clinical outcomes were correlated with results of dynamic MR imaging and pharmacokinetic analysis. RESULTS: On dynamic MR images of the surgical patients, areas with intense homogeneous enhancement showed increased permeability (k = 27.4 x 10(-3)) compared with areas with poor enhancement (k = 19.0 x 10(-3)). Well-enhanced areas were predominantly composed of cancer cell fascicles, whereas poorly enhanced areas were composed of fibrous tissue with scattered cancer cells. Radiation therapy was more effective in tumors with higher tissue permeability (k = 31.3 x 10(-3)) on dynamic MR images than in those with lower tissue permeability (k = 18.3 x 10(-3)). CONCLUSION: Areas of increased contrast enhancement are mainly composed of abundant cancer cell fascicles, whereas poorly perfused areas are composed of fibrous tissue with scattered cancer cells. Radiation therapy is more effective in well-enhanced tumors, resulting in improved local control.

Adenocarcinoma↗
PubMed2000

Evaluation of phosphate removal from water by immobilized phosphate-binding protein PstS.

The phosphate (P(i))-binding protein PstS is a member of a family of periplasmic proteins that act as high-affinity receptors for active transport systems in bacteria. PstS protein purified from Pseudomonas aeruginosa was immobilized to N-hydroxysuccinimide-activated Sepharose, packed into a plastic column (5 x 70 mm), and examined for its potential ability to remove P(i) from water. The PstS-Sepharose column completely removed P(i) from 32P-labeled pond water containing about 0.5 microM P(i) (0.015 mg P per liter). More than 90% of 32P-P(i) that was retained in the column could be eluted by washing with low-pH water.

Journal Article↗
PubMed2000

Mutational analysis of the multicopy hao gene coding for hydroxylamine oxidoreductase in Nitrosomonas sp. strain ENI-11.

The ammonia-oxidizing bacterium Nitrosomonas sp. strain ENI-11 contains three copies of the hao gene (hao1, hao2, and hao3) coding for hydroxylamine oxidoreductase (HAO). Three single mutants (hao1::kan, hao2::kan, or hao3::kan) had 68 to 75% of the wild-type growth rate and 58 to 89% of the wild-type HAO activity when grown under the same conditions. A double mutant (hao1::kan and hao3::amp) also had 68% of the wild-type growth and 37% of the wild-type HAO activity.

DNA Mutational Analysis↗
PubMed2000

Molecular analysis of polyphosphate accumulation in bacteria.

The dynamic behavior of inorganic polyphosphate (polyP), its accumulation and disappearance, is the most striking aspect of polyP metabolism in bacteria. Imbalance between polyP synthesis and degradation results in fluctuations of polyP by 100- to 1000-fold. We here review recent results with respect to this polyP metabolism in bacteria. PolyP accumulation in response to amino acid starvation, accompanied by increased levels of stringent factors, has been observed in Escherichia coli. Inhibition by stringent factors of polyphosphatase interrupts the dynamic balance between the synthesis and degradation of polyP, accounting for polyP accumulation. Polyphosphate kinase is required for activation of intracellular protein degradation, which is required for adaptation at the onset of amino acid starvation. The adaptation to amino acid starvation is mediated by the network of stringent response and polyP metabolism. PolyP accumulation independent of stringent response has also been observed. Novobiocin, an inhibitor for DNA gyrase, stimulated accumulation of polyP but not that of stringent factors. However, a temperature-sensitive DNA gyrase mutant did not exhibit polyP accumulation at the non-permissive temperature. Antagonistic relationship of polyP to nucleic acid synthesis, explored by Harold, appears to be more complicated. We discuss relationship of Pi regulation to polyP accumulation in E. coli and Klebsiella aerogenes. A function of polyP as an in vivo phosphagen affecting polyP accumulation is also discussed.

Adaptation, Physiological↗
PubMed1999

Inorganic polyphosphate kinase is required to stimulate protein degradation and for adaptation to amino acid starvation in Escherichia coli.

Inorganic polyphosphate (polyP) kinase was studied for its roles in physiological responses to nutritional deprivation in Escherichia coli. A mutant lacking polyP kinase exhibited an extended lag phase of growth, when shifted from a rich to a minimal medium (nutritional downshift). Supplementation of amino acids to the minimal medium abolished the extended growth lag of the mutant. Levels of the stringent response factor, guanosine 5'-diphosphate 3'-diphosphate, increased in response to the nutritional downshift, but, unlike in the wild type, the levels were sustained in the mutant. These results suggested that the mutant was impaired in the induction of amino acid biosynthetic enzymes. The expression of an amino acid biosynthetic gene, hisG, was examined by using a transcriptional lacZ fusion. Although the mutant did not express the fusion in response to the nutritional downshift, Northern blot analysis revealed a significant increase of hisG-lacZ mRNA. Amino acids generated by intracellular protein degradation are very important for the synthesis of enzymes at the onset of starvation. In the wild type, the rate of protein degradation increased in response to the nutritional downshift whereas it did not in the mutant. Supplementation of amino acids at low concentrations to the minimal medium enabled the mutant to express the hisG-lacZ fusion. Thus, the impaired regulation of protein degradation results in the adaptation defect, suggesting that polyP kinase is required to stimulate protein degradation.

Adaptation, Physiological↗
PubMed1999

Presence of phospholipid-neutral lipid complex structures in atherosclerotic lesions as detected by a novel monoclonal antibody.

A novel monoclonal antibody (ASH1a/256C) that recognizes atherosclerotic lesions in human and Watanabe heritable hyperlipidemic (WHHL) rabbit aortae is described. When (123)I-labeled ASH1a/256C antibody is injected intravenously into WHHL rabbits, it associates specifically with fatty streaks on the aorta. The antigen recognized by the antibody is lipid, based on extraction with chloroform and methanol from WHHL rabbit tissues. The antigen, purified by high performance liquid chromatography, was shown to be phosphatidylcholine (PC), which contains unsaturated fatty acyl groups based on analyses utilizing (1)H and (13)C nuclear magnetic resonance, Fourier transfer-infrared spectrum, and mass spectrometry. The antibody did not react with other classes of phospholipids or neutral lipids when tested using an enzyme-linked immunosorbent assay. When PC was mixed with either cholesterol, cholesteryl ester, or triacylglycerol, however, the reactivity of the antibody to PC increased up to 8-fold. Homogenates of aorta tissue obtained from normal and WHHL rabbits were fractionated using sucrose density gradient ultracentrifugation in which neutral lipid droplets, cellular membranes, and proteins are separated. The phospholipid content in cellular membrane fractions from WHHL rabbits was twice as high as that of normal rabbits, and there was an enormous difference in the antigenic activity in these fractions. The content of cholesterol in the cellular membrane fraction of WHHL rabbits was approximately 50 times higher than that of normal rabbits. Addition of neutral lipids to the cellular membrane fraction of normal rabbit markedly increased the antigenic activity. Atheromatous lesions in thickened WHHL rabbit aortic intima that were rich in lipid droplets were stained positively with ASH1a/256C immunohistochemically. These results strongly suggest that PC-neutral lipid complex domains are formed in atherosclerotic lesions.

Animals↗
PubMed1999

A novel in vitro experimental model for ovarian endometriosis: the three-dimensional culture of human ovarian surface epithelial cells in collagen gels.

OBJECTIVE: To develop an in vitro experimental model of ovarian endometriosis using human cells and to investigate the pathogenesis of endometriosis. DESIGN: Controlled in vitro coculture study. SETTING: A department of obstetrics and gynecology at a university hospital. PATIENT(S): Ovaries and endometrium were obtained from patients who underwent a hysterectomy because of gynecologic disease. INTERVENTION(S): Human ovarian surface epithelial (OSE) cells were cultured alone and OSE cells and endometrial stromal (ES) cells were cultured together in a three-dimensional collagen gel culture system with or without the addition of E2. MAIN OUTCOME MEASURE(S): The aggregated collagen gels containing the cultured cells were examined morphologically. RESULT(S): The OSE cells in single culture with E2 formed circular arrangements. These cells were immunohistochemically positive for cytokeratin but negative for epithelial membrane antigen. In the cocultures of OSE and ES cells with E2, the OSE cells formed a lumen structure surrounded by ES cells. Immunoreactivity for cytokeratin and epithelial membrane antigen was detected in the glandular cells and cilia were identified on the cell surface by electron microscopy. Without the addition of E2, no structures were detected. CONCLUSION(S): A new in vitro experimental model was established with the aid of human OSE cells. Endometriotic lesions can arise through a process of metaplasia from OSE cells in the presence of E2 and ES cells.

Adult↗
PubMed1999

A follicle-stimulating hormone-secreting gonadotroph adenoma with ovarian enlargement in a 10-year-old girl.

OBJECTIVE: To report a rare case of gonadotroph adenoma accompanied by ovarian enlargement in a child. DESIGN: Case report. SETTING: A university hospital. PATIENT(S): A 10-year-old Japanese girl with multiple cysts of both ovaries. INTERVENTION(S): Endocrinologic assays, immunohistochemical staining, ultrastructural observations, and in vitro analysis. MAIN OUTCOME MEASURE(S): The endocrinologic assays showed an elevated serum FSH level. The tumor cells excised from the gonadotroph adenoma were immunohistochemically positive for antihuman FSH monoclonal antibody. When cultured in vitro, the tumor cells secreted FSH in the primary culture. RESULT(S): The gonadotroph adenoma produced FSH. After transsphenoidal surgery, both ovaries decreased in size. CONCLUSION(S): The ovarian enlargement was induced by endogenous FSH from the gonadotroph adenoma. To our knowledge, this is the first reported case of gonadotroph adenoma accompanied by ovarian enlargement in childhood or adolescence.

Adenoma↗