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Biomedical subjects

H Ohta

Publications and source records attributed to H Ohta.

At least 19 recordsLinked to original sources

Magnesium insertion by magnesium chelatase in the biosynthesis of zinc bacteriochlorophyll a in an aerobic acidophilic bacterium Acidiphilium rubrum.

To elucidate the mechanism for formation of zinc-containing bacteriochlorophyll a in the photosynthetic bacterium Acidiphilium rubrum, we isolated homologs of magnesium chelatase subunits (bchI, -D, and -H). A. rubrum bchI and -H were encoded by single genes located on the clusters bchP-orf168-bchI-bchD-orf320-crtI and bchF-N-B-H-L as in Rhodobacter capsulatus, respectively. The deduced sequences of A. rubrum bchI, -D, and -H had overall identities of 59. 8, 40.5, and 50.7% to those from Rba. capsulatus, respectively. When these genes were introduced into bchI, bchD, and bchH mutants of Rba. capsulatus for functional complementation, all mutants were complemented with concomitant synthesis of bacteriochlorophyll a. Analyses of bacteriochlorophyll intermediates showed that A. rubrum cells accumulate magnesium protoporphyrin IX monomethyl ester without detectable accumulation of zinc protoporphyrin IX or its monomethyl ester. These results indicate that a single set of magnesium chelatase homologs in A. rubrum catalyzes the insertion of only Mg(2+) into protoporphyrin IX to yield magnesium protoporphyrin IX monomethyl ester. Consequently, it is most likely that zinc-containing bacteriochlorophyll a is formed by a substitution of Zn(2+) for Mg(2+) at a step in the bacteriochlorophyll biosynthesis after formation of magnesium protoporphyrin IX monomethyl ester.

Acetobacteraceae

High dose chemotherapy for refractory urothelial carcinoma supported by peripheral blood stem cell transplantation.

BACKGROUND: Chemotherapy with methotrexate (MTX), vinblastine, doxorubicin, and cisplatin (M-VAC) is reported to be the most effective regimen for urothelial carcinoma. Complete response (CR) is observed in many cases. However, to the authors' knowledge there is no alternative therapy for nonresponders. Thus, the authors attempted high dose chemotherapy (HDC) supported with peripheral blood stem cells (PBSCs) collected after a modified method of mobilization to yield sufficient PBSCs for the HDC regimen employed. METHODS: PBSCs were collected from ten patients, all of whom had recurrent and/or refractory transitional cell carcinoma. They were treated by modified M-VAC (with pirarubicin in place of doxorubicin) for PBSC harvest. Seven micrograms per kilogram of body weight of granulocyte-colony stimulating factor was injected subcutaneously daily from Day 10 of treatment to the end of the harvest. Harvest was initiated from the day when peripheral leukocyte counts exceeded 10,000/microL and usually continued for 3 consecutive days. Each patient received two courses of HDC. Therefore, 20 courses of HDC comprised of 300 mg/body of MTX, 1500 mg/m(2) of etoposide, and high dose carboplatin (CBDCA) were given to these 10 patients. The dose of CBDCA was determined by the formula of Calvert et al., in which the target area under the concentration versus time curve of CBDCA was adjusted to 21 mg. minute/mL. RESULTS: Sufficient PBSCs were collected for myeloablative chemotherapy in all patients. No patient responded to the treatment with modified M-VAC. Response to HDC was observed in nine of ten patients. CR was achieved in seven patients and a partial response was noted in two patients. A patient with multiple bone metastases showed no response. All patients rapidly recovered after PBSC transplantation. No patient died of treatment-related toxicity. CONCLUSIONS: HDC supported by PBSC transplantation was found to have a remarkable response against refractory urothelial carcinoma, for which there was no alternative therapy.

Aged

Characterization of cis-elements required for the transcriptional activation of the rae28/mph1 gene in F9 cells.

The rae28/mph1 gene is the mouse homologue of the Drosophila polyhomeotic gene, which plays a crucial role in the maintenance of the transcriptional repression state of Hox genes. Expression of the rae28/mph1 gene is induced during retinoic acid (RA)-mediated differentiation of embryonal carcinoma F9 cells. By transient-transfection experiments, we identified a pair of inverted differentiation response sequences (DRS(s)) in the 5' flanking region. Each of the DRS(s) contained the consensus sequence [5'-CCTCCCCXCXGCCCCCTCCXCXC-3'], which is also conserved in the human counterpart of the rae28/mph1 gene. Electrophoretic mobility shift assay and DNase I foot printing with nuclear extracts derived from F9 cells demonstrated the presence of novel DNA-binding factors which specifically interact with DRS(s). Nucleotide substitutions in the 3' DRS abrogated the factor binding and the transcriptional activation, suggesting that DRS(s) and DRS-binding factors play an important role in the transcriptional regulation of the rae28/mph1 gene.

Animals

Preparation of uniformly sized polymeric separation media potentially suitable for small-scale high-performance liquid chromatography and/or capillary electrochromatography.

Uniformly sized polymer particles were prepared by either a two-step swelling and polymerization method or a Shirasu porous glass (SPG) emulsification technique to compare their suitability as a uniformly sized packing material for small-scale high-performance liquid chromatography (HPLC) or capillary electrochromatography (CEC). The SPG emulsification technique afforded slightly worse size uniformity compared to the two-step swelling and polymerization technique. However, fairly nice spherical shapes with reproducible outward appearance and internal pore size distribution were obtained for both of 3- or 6-micron sized particles. On the other hand, the two-step swelling and polymerization method afforded broken particles with quite different outward appearances due to the polymeric porogen effects of seed polymer utilized as the shape template. In HPLC, the column packed with the 3-micron particles prepared with the SPG emulsification technique proved to have a fairly high column efficiency with good column stability, as assessed under repeated use in gradient elution. On the other hand, the column packed with the packing material obtained through the two-step swelling and polymerization method showed much poorer column stability, while initial column efficiency was compatible to that obtained using the SPG emulsification method. In addition, the packing material prepared with the SPG emulsification technique could be modified with ion-exchangeable monomers and showed fairly good column efficiency in the CEC mode.

Chromatography, High Pressure Liquid

Comparison of intrinsic activities of the putative sphingosine 1-phosphate receptor subtypes to regulate several signaling pathways in their cDNA-transfected Chinese hamster ovary cells.

We examined the actions of sphingosine 1-phosphate (S1P) on signaling pathways in Chinese hamster ovary cells transfected with putative S1P receptor subtypes, i.e. Edg-1, AGR16/H218 (Edg-5), and Edg-3. Among these receptor-transfected cells, there was no significant difference in the expressing numbers of the S1P receptors and their affinities to S1P, which were estimated by [(3)H]S1P binding to the cells. In vector-transfected cells, S1P slightly increased cytosolic Ca(2+) concentration ([Ca(2+)](i)) in association with inositol phosphate production, reflecting phospholipase C activation; the S1P-induced actions were markedly enhanced in the Edg-3-transfected cells and moderately so in the AGR16-transfected cells. In comparison with vector-transfected cells, the S1P-induced [Ca(2+)](i) increase was also slightly enhanced in the Edg-1-transfected cells. In all cases, the inositol phosphate and Ca(2+) responses to S1P were partially inhibited by pertussis toxin (PTX). S1P also significantly increased cAMP content in a PTX-insensitive manner in all the transfected cells; the rank order of their intrinsic activity of S1P receptor subtypes was AGR16 > Edg-3 > Edg-1. In the presence of forskolin, however, S1P significantly inhibited cAMP accumulation at a lower concentration (1-100 nM) of S1P in a manner sensitive to PTX in the Edg-1-transfected cells but not in either the Edg-3 or AGR16-transfected cells. As for cell migration activity evaluated by cell number across the filter of blind Boyden chamber, Edg-1 and Edg-3 were equally potent, but AGR16 was ineffective. Thus, S1P receptors may couple to both PTX-sensitive and -insensitive G-proteins, resulting in the selective regulation of the phospholipase C-Ca(2+) system, adenylyl cyclase-cAMP system, and cell migration activity, according to the receptor subtype.

Adenylate Cyclase Toxin

Cloning, expression of the psbU gene, and functional studies of the recombinant 12-kDa protein of photosystem II from a red alga Cyanidium caldarium.

The encoding extrinsic 12-kDa protein of oxygen-evolving PS II complex from a red alga, Cyanidium caldarium, was cloned and sequenced by means of PCR and a rapid amplification of cDNA ends (RACE) procedure. The gene encodes a putative polypeptide of 154 amino acids with a calculated molecular mass of 16,714 Da. The full sequence of the protein includes two characteristic transit peptides, one for transfer across the chloroplast envelope and another for targeting into the thylakoid lumen. This indicates that the protein is encoded in the nuclear genome. The mature protein consists of 93 amino acids with a calculated molecular mass of 10,513 Da. The cloned gene was successfully expressed in Escherichia coli and the resulting protein was purified, reconstituted to CaCl2-washed PS II complex together with the other extrinsic proteins of 33 and 20 kDa and cyt c-550. The recombinant 12-kDa protein bound completely with the PSII complex, which resulted in a restoration of oxygen evolution equal to the level achieved by binding of the native 12-kDa protein.

Amino Acid Sequence

Isolation of MHC class I-restricted tumor antigen peptide and its precursors associated with heat shock proteins hsp70, hsp90, and gp96.

We have previously demonstrated that vaccination with heat shock proteins hsp70, hsp90, and gp96 elicits specific immunity against the tumor from which the hsps were purified. Although the association of tumor Ag peptides with these hsps have been suggested, the identification of the peptides or their precursors stripped from the hsps remained to be resolved. We show in this report that an Ld-restricted cytotoxic T lymphocyte epitope of a mouse leukemia RLmale symbol1 and its precursors are associated with the chaperones hsp90 and hsp70 in the cytosol and gp96 in the lumen of the endoplasmic reticulum. Hsp70 was associated with only final sized octamer, while hsp90 was found to associate with the octamer and two distinct precursor peptides. The gp96 was associated with the octamer and one of the two precursors. Thus, each of the hsps bound a distinct set of peptides. Our results have demonstrated for the first time that the hsps associate not only with final sized tumor Ag peptide but also with its precursors. The implication of this evidence is also discussed in terms of the roles of hsps in MHC class I Ag processing/presentation.

Animals

Activation of phospholipase C-Ca2+ system by sphingosine 1-phosphate in CHO cells transfected with Edg-3, a putative lipid receptor.

Sphingosine 1-phosphate (S1P) induces phospholipase C (PLC) activation and Ca2+ mobilization in many types of cells. We examined the possible involvement of Edg-3, one of the putative S1P receptors, in the phospholipase C (PLC)-Ca2+ system. S1P increased the cytoplasmic free Ca2+ concentration without detectable inositol phosphate production in vector-transfected CHO cells. In the Edg-3-transfected cells, however, the S1P-induced Ca2+ response was clearly enhanced, which was associated with a significant production of inositol phosphate. These S1P-induced responses in the Edg-3-transfected cells were inhibited by U73122, a potent PLC inhibitor. We conclude that Edg-3 may be one of the S1P receptors participating in the activation of the PLC-Ca2+ system.

Animals

CD28-deficient mice are highly resistant to collagen-induced arthritis.

CD28 provides a critical costimulatory signal in Ag-specific T cell activation. Recent studies have revealed an important role for CD28 in the development of autoimmune diseases. We have examined the role of CD28 in collagen-induced arthritis (CIA) by inducing CIA in CD28-deficient DBA/1 mice. CD28-deficient mice never developed arthritis and showed markedly decreased levels of IgG and IgM anti-type II collagen (CII) Abs. In addition, the CD28+/- mice had similar levels of IgG1 and IgG2a anti-CII Abs, whereas in the CD28-deficient mice the level of IgG1 anti-CII Abs was decreased compared with that of IgG2a. IFN-gamma production by lymph node cells in response to CII was also reduced. CD28-deficient mice were either immunized four times with CII in CFA to augment Ag loading or given low doses of IL-12 to enhance Thl type responses. Both treatments resulted in a very low incidence of CIA development and minimal disease. CD28-deficient mice developed arthritis from injection of lymph node cells from CII-immunized wild-type mice, followed by immunization with CII in CFA. Taken together, these results indicate that costimulation of CD28 cannot be replaced by repeated activation through TCR or other costimulatory molecules. Thus, CD28 plays a critical role in both cellular and humoral immunity against CII and is indispensable for the development of CIA.

Adoptive Transfer

Volumetric comparisons on some nuclei in the cerebellar complex of prosimians.

Seven measurements were performed on the cerebellar complex of 30 specimens, covering three species each of Cheirogaleidae, Lemuridae and Indriidae, and Daubentonia, and three each of Lorisinae, Galaginae, and Tarsius. The items measured were the volume of the medial (CM), interposed (CI), and lateral (CL) cerebellar nuclei, ventral pons (VPo), inferior olivary principal (OLIPr) and accessory (OLIAc) nuclei, and the vestibular nuclear complex (VES). The raw data for these measurements were previously reported [Matano et al., Folia Primatol 44:171-181, 182-203, 1985; 47:189-203, 1986; Matano, Anthropol Soc Nippon 100:69-82, 1992]. For this paper, the relative size of each nucleus was expressed in terms of size indices based upon the allometric line obtained by reduced major axis analysis and comparisons between species within family or subfamily were made. Lemur showed one of the highest cerebellar complex indices and Lepilemur one of the lowest. Generally, the three cerebellar nuclei (CM, CI, and CL) were enlarged to the same extent in each species. Only Daubentonia showed higher size indices of CL, VPo, and OLIPr than of CM and OLIAc. Characteristics of the cerebellar complex enlargement of Tarsius were comparable to those of prosimians. The VES indices for non-leaping Lorisinae were markedly lower than those for the actively leaping Galago and Tarsius.

Animals

Biocatalytic asymmetric decarboxylation.

Biocatalytic decarboxylation is a unique reaction, in the sense that it can be considered to be a protonation reaction to a "carbanion equivalent" intermediate in aqueous medium. Thus, if optically active compounds can be prepared via this type of reaction, it would be a very characteristic biotransformation, as compared to ordinary organic reactions. An enzyme isolated from a specific strain of Alcaligenes bronchisepticus catalyzes the asymmetric decarboxylation of alpha-aryl-alpha-methylmalonic acid to give optically active alpha-arylpropionic acids. The effect of additives revealed that this enzyme requires no biotin, no co-enzyme A, and no ATP, as ordinary decarboxylases and transcarboxylases do. Studies on inhibitors of this enzyme and spectroscopic analysis made it clear that the Cys residue plays an essential role in the present reaction. The unique reaction mechanism based on these results and kinetic data in its support are presented.

Alcaligenes

Hepatic lymph node involvement in resected cases of liver metastases from colorectal cancer.

PURPOSE: Lymph node metastasis in the hepatoduodenal ligament is known as one of the most significant prognostic factors after liver resection for colorectal metastasis. However, there have been very few articles on the clinical features of node-positive patients and on detailed distribution of positive nodes. Further, there has been no established strategy on how to handle hepatic lymph nodes during liver resection. To address these subjects, a retrospective study was conducted. METHODS: During the period of 1980 through April 1998, 182 hepatic resections were performed for metastatic colorectal carcinoma. Of these, 78 cases had hepatic lymph node sampling during the operation. Distribution of positive nodes, location of liver metastasis, stage of the primary lesion, and outcome after liver resection were analyzed. RESULTS: Nine cases (12 percent) had secondary lymph node metastases in the hepatoduodenal ligament. The incidence was slightly higher (13.5 percent) in the most recent 44 consecutive cases. There was a tendency for liver metastases in the right lobe to metastasize to No. 12b (or node of the foramen of Winslow, lymph nodes along the common bile duct) and liver metastases in the left lobe to metastasize to No. 8a (anterosuperior group of the lymph nodes along the common hepatic artery). Outcome of node-positive patients (n = 9) was extremely poor (P < 0.001) compared with that of node-negative patients (n = 66), and the most common site of recurrence in the node-positive patients was remnant liver and hepatic lymph nodes. Preoperatively, there were no significant predicting factors for positive hepatic lymph nodes. CONCLUSIONS: No. 8a and No. 12b nodes are principal nodes that should be palpated and sampled during liver resection to check the secondary lymphatic spread from liver metastases. Hepatic nodal involvement indicates the progression of disease beyond simple liver metastases and may not be the indication for simple surgical removal. Further study, including hepatoduodenal dissection and systemic adjuvant chemotherapy, may elucidate the survival benefit, if any, of liver resection in node-positive patients.

Case-Control Studies

Zinc accumulation and metallothionein gene expression in the proliferating epidermis during wound healing in mouse skin.

Metallothionein (MT), a low molecular weight metal-binding protein, has been related to zinc and copper metabolism, the acute-phase response, and cellular proliferation. In this study, we investigated changes in zinc metabolism and MT gene expression occurring in tissue damage and repair during wound healing in mouse skin. Northern blot analysis revealed that a significant increase of MT mRNA was observed in the liver for 18 h after wounding, and serum zinc downfall and hepatic zinc uptake were observed. In situ hybridization analysis showed that no significant expression of MT mRNA was detected within the first 9 h after wounding. However, it was expressed restrictively in the proliferating epidermis of the wound margin after 12 h. Zinc began to accumulate in wounded skin after MT gene expressed. Northern blotting and immunocytochemical staining revealed that MT has been synthesized actively during the growth phase compared with the stationary phase in normal human epidermal keratinocytes in vitro. Intracellular zinc accumulation was observed in the proliferating cells. We concluded that hepatic MT plays an important role as an acute phase protein against host damage, and epidermal MT contributes in the supply of zinc to wounded tissue and activates proliferation for the regeneration of epidermis.

Animals

Mucin-producing biliary papillomatosis associated with gastrobiliary fistula.

We report a case of mucin-producing biliary papillomatosis in a 78-year-old woman. Abdominal ultrasound (US) and computed tomography (CT) showed wall thickening and dilatation of the intrahepatic bile duct (IHBD), as well as a nodular lesion, 1.2 cm in diameter, in the left branch of the IHBD. Gastric endoscopy revealed excretion of bile-containing mucin on the anterior wall of the body of the stomach. Endoscopic ultrasonography (EUS) showed gastrobiliary fistula and discharge of mucin into the stomach. Needle biopsy of the biliary tumor revealed papillary proliferation, but no malignant cells were recognized histologically. Therefore this patient was diagnosed as having mucin-producing biliary papillomatosis forming gastrobiliary fistula. She did not present with obstructive jaundice, probably because of the fistula. She is alive, without obstructive jaundice, 16 months after the diagnosis without having had surgery. This is, to our knowledge, the first reported case of biliary papillomatosis forming gastrobiliary fistula and with the patient free of obstructive jaundice.

Aged

Cardiac tamponade originating from primary gastric signet ring cell carcinoma.

A 45-year-old man with dry cough and dyspnea was referred by a medical practitioner for evaluation of heart failure on February 10, 1996. Chest X-ray revealed increased cardiothoracic ratio, and ultrasonographic echocardiography disclosed massive pericardial effusion with right ventricular collapse. Cardiac tamponade was diagnosed and pericardiocentesis was performed. Ten days after admission, the pleural effusion had become more pronounced, and thoracocentesis was performed. Carcinoembryonic antigen level was elevated in both the pericardial and pleural effusion, and cytology implicated adenocarcinoma, which suggested malignant effusion. Endoscopic study disclosed gastric cancer in the posterior wall of the upper body, and the histopathological diagnosis was signet-ring cell carcinoma. The patient died of respiratory failure on May 2, 1996, and autopsy was performed. The final diagnosis was gastric cancer with pulmonary lymphangitis, pericarditis, and pleuritis carcinomatosa, accompanied by enlargement of mediastinal and paraaortic lymph nodes. Interestingly, the primary signet-ring cell carcinoma of the stomach was situated mostly in the mucosa. Deep in the submucosal region, there was prominent invasion of the intralymphatic vessels, without direct destruction of the mucosa muscularis.

Carcinoma, Signet Ring Cell

A simple immunoradiometric assay for measuring the entire molecules of adrenomedullin in human plasma.

We developed a one-step two-site immunoradiometric assay (IRMA) using two kinds of monoclonal antibodies, which enables us to directly measure the entire molecules of adrenomedullin (AM) (the sum of mature-type AM (abbreviated, m-AM) amidated at the C-terminus and Gly-extended non-amidated AM) in human plasma using a small amount of sample (100 microl) without prior extraction. The detection limit of this assay was 0.5 pmol/l for a 100-microl sample. Intra- and inter-assay precisions were 3.4-7.3% and 5.8-7.6%, respectively. The dilution curves of plasma samples showed good linearity and analytical recovery was 89-118%. The mean total AM in plasma of healthy subjects was 9.00+/-2.13 pmol/l, whereas m-AM was 1.05+/-0.24 pmol/l. This method, together with our previously reported simplified method to specifically measure m-AM (Ohta et al., Clin Chem 1999;45:244-251), allows facile estimation of the plasma concentration of AM-Gly by subtracting m-AM from the total AM measured by the procedure described in this paper. We were able to show that the concentration of total AM in patients with sepsis was markedly higher than that in the healthy controls and that the ratios of m-AM/total AM were significantly different between the controls and patients.

Adrenomedullin

Rheologic analysis of gastric mucosal hemodynamics in patients with cirrhosis.

BACKGROUND: Portal hypertensive gastropathy causes some gastric mucosal microcirculatory disorders in cirrhotic patients, but the nature of the rheologic dysfunction in the gastric microcirculation remains to be clarified. METHODS: To examine the rheologic properties of the gastric microcirculation, we subjected 112 cirrhotic patients and 51 control subjects to endoscopic laser Doppler flowmetry and measured multiple variables of flow, red blood cell volume, and velocity. Furthermore, based on these results, we analyzed the shear rate which reflects the status of the microcirculatory system. To validate the laser Doppler flowmetry, we derived the relationship between red blood cell volume and cross-sectional areas of submucosal collecting venules; near-infrared endoscopy was used to evaluate this relationship. RESULTS: Analysis of shear rate according to the severity of portal hypertensive gastropathy showed that the mucosa was exposed to strong hemokinetic stress in severe cases, characterized by a higher shear rate than in control subjects or in mild cases. Nitroglycerin, administered by intravenous infusion (1.0 microg/kg/min), reduced blood flow and restored shear rate to control levels in patients with severe portal hypertensive gastropathy. CONCLUSION: This rheologic study of the gastric mucosa suggests that a disorder of the shear rate control mechanism in the microcirculation is associated with severe portal hypertensive gastropathy.

Endoscopy, Digestive System