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Biomedical subjects

Y Katayama

Publications and source records attributed to Y Katayama.

At least 217 records · Page 12Linked to original sources
PubMed1999

Characterization of the meta-cleavage compound hydrolase gene involved in degradation of the lignin-related biphenyl structure by Sphingomonas paucimobilis SYK-6.

Sphingomonas paucimobilis SYK-6 has the ability to transform a lignin-related biphenyl compound, 2,2'-dihydroxy-3,3'-dimethoxy-5, 5'-dicarboxybiphenyl (DDVA), to 5-carboxyvanillic acid (5CVA) via 2, 2',3-trihydroxy-3'-methoxy-5,5'-dicarboxybiphenyl (OH-DDVA). In the 4.9-kb HindIII fragment containing the OH-DDVA meta-cleavage dioxygenase gene (ligZ), we found a novel hydrolase gene (ligY) responsible for the conversion of the meta-cleavage compound of OH-DDVA to 5CVA. Incorporation of 18O from H218O into 5CVA indicated there was a hydrolytic conversion of the OH-DDVA meta-cleavage compound to 5CVA. LigY exhibited hydrolase activity only toward the meta-cleavage compound of OH-DDVA, suggesting its restricted substrate specificity.

Amino Acid Sequence↗
PubMed1999

Genetic and biochemical characterization of a 2-pyrone-4, 6-dicarboxylic acid hydrolase involved in the protocatechuate 4, 5-cleavage pathway of Sphingomonas paucimobilis SYK-6.

Sphingomonas paucimobilis SYK-6 is able to grow on a wide variety of dimeric lignin compounds with guaiacyl moieties, which are converted into protocatechuate by the actions of lignin degradation enzymes in this strain. Protocatechuate is a key metabolite in the SYK-6 degradation of lignin compounds with guaiacyl moieties, and it is thought that it degrades to pyruvate and oxaloacetate via the protocatechuate 4,5-cleavage pathway. In a 10.5-kb EcoRI fragment carrying the protocatechuate 4,5-dioxygenase gene (ligAB) (Y. Noda, S. Nishikawa, K. Shiozuka, H. Kadokura, H. Nakajima, K. Yoda, Y. Katayama, N. Morohoshi, T. Haraguchi, and M. Yamasaki. J. Bacteriol. 172:2704-2709, 1990), we found the ligI gene encoding 2-pyrone-4, 6-dicarboxylic acid (PDC) hydrolase. PDC hydrolase is a member of this pathway and catalyzes the interconversion between PDC and 4-carboxy-2-hydroxymuconic acid (CHM). The ligI gene is thought to be transcribed divergently from ligAB and consists of an 879-bp open reading frame encoding a polypeptide with a molecular mass of 32,737 Da. The ligI gene product (LigI), expressed in Escherichia coli, was purified to near-homogeneity and was estimated to be a monomer (31.6 kDa) by gel filtration chromatography. The isoelectric point was determined to be 4.9. The optimum pH for hydrolysis of PDC is 8.5, the optimum pH for synthesis of PDC is 6.0 to 7.5, and the Km values for PDC and CHM are 74 and 49 microM, respectively. LigI activity was inhibited by the addition of thiol reagents, suggesting that the cysteine residue is a catalytic site. LigI is more resistant to metal ion inhibition than the PDC hydrolases of Pseudomonas ochraceae (K. Maruyama, J. Biochem. 93:557-565, 1983) and Comamonas testosteroni (P. J. Kersten, S. Dagley, J. W. Whittaker, D. M. Arciero, and J. D. Lipscomb, J. Bacteriol. 152:1154-1162, 1982). The insertional inactivation of the ligI gene in S. paucimobilis SYK-6 led to the complete loss of PDC hydrolase activity and to a growth defect on vanillic acid; it did not affect growth on syringic acid. These results indicate that the ligI gene is essential for the growth of SYK-6 on vanillic acid but is not responsible for the growth of SYK-6 on syringic acid.

Carboxylic Ester Hydrolases↗
PubMed1999

Human CD46 enhances nitric oxide production in mouse macrophages in response to measles virus infection in the presence of gamma interferon: dependence on the CD46 cytoplasmic domains.

CD46 is a transmembrane complement regulatory protein widely expressed on nucleated human cells. Laboratory-adapted strains of measles virus (MV) bind to the extracellular domains of CD46 to enter human cells. The cytoplasmic portion of CD46 consists of a common juxtamembrane region and different distal sequences called Cyt1 and Cyt2. The biological functions of these cytoplasmic sequences are unknown. In this study, we show that expression of human CD46 with the Cyt1 cytoplasmic domain in mouse macrophages enhances production of nitric oxide (NO) in response to MV infection in the presence of gamma interferon (IFN-gamma). Human CD46 does not increase the basal levels of NO production in mouse macrophages and does not augment NO production induced by double-stranded polyribonucleotides. Replacing the cytoplasmic domain of human CD46 with Cyt2 reduces MV and IFN-gamma-induced NO production in mouse macrophages. Deleting the entire cytoplasmic domains of human CD46 does not prevent MV infection but markedly attenuates NO production in response to MV and IFN-gamma. Mouse macrophages expressing a tailless human CD46 mutant are more susceptible to MV infection and produce 2 to 3 orders of magnitude more infectious virus than mouse macrophages expressing human CD46 with intact cytoplasmic domains. These results reveal a novel function of CD46 dependent on the cytoplasmic domains (especially Cyt1), which augments NO production in macrophages. These findings may have significant implications for roles of CD46 in innate immunity and MV pathogenesis.

Animals↗
PubMed1999

Changes in cerebral blood oxygenation of the frontal lobe induced by direct electrical stimulation of thalamus and globus pallidus: a near infrared spectroscopy study.

OBJECTIVE: Blood oxygenation level dependent (BOLD) contrast functional MRI images show activated cortical areas by detecting a reduced concentration of deoxyhaemoglobin (deoxy-Hb) during neuronal activity; however, near infrared spectroscopy (NIRS) has shown various patterns of cerebral blood oxygenation (CBO) changes in the frontal lobe during cognitive tasks. To determine if various patterns of CBO changes occur in the frontal lobe when the brain is directly stimulated, changes in CBO in the frontal lobe induced by deep brain stimulation in patients with implanted electrodes were evaluated. METHODS: Six patients were studied, including five with Parkinson's disease and one with essential tremor. To reduce tremor or rigidity, the electrodes were implanted at the thalamic nucleus ventralis intermedius (VIM: three Parkinson's disease and one essential tremor) or the globus pallidus internus (GPi: two Parkinson's disease). Using NIRS, changes of deoxy-Hb, oxyhaemoglobin (oxy-Hb) and total haemoglobin (total Hb) were measured in the bilateral frontal lobes during various stimulus conditions. RESULTS: High frequency (120 Hz) GPi stimulation consistently increased oxy-Hb and total Hb with a decrease of deoxy-Hb in an intensity and time dependent manner. Oxy-Hb and total Hb increased immediately after the onset of stimulation and then gradually decreased when stimulation was continued. By contrast, high frequency (120 Hz) VIM stimulation decreased oxy-Hb, deoxy Hb and total Hb in an intensity dependent manner. In the severe tremor patient with VIM stimulation, frequency response was examined by decreasing stimulus frequencies; deoxy-Hb increased at high frequencies (70-40 Hz), and then decreased below the control level at low frequencies (30-0 Hz), whereas oxy-Hb and total Hb increased consistently at high and low frequencies. CONCLUSION: The electrical stimulation of GPi and VIM caused various CBO changes in the frontal lobe, which were similar to those found during cognitive tasks. Such a multiplicity of CBO changes in the frontal lobe may be caused by complex neuronal circuits in the frontal lobe which has many neuronal connections to other cortical areas or the basal ganglia.

Aged↗
PubMed1999

The cDNA sequences of equine antioxidative enzyme genes Cu/Zn-SOD and Mn-SOD, and these expressions in equine tissues.

The entire cDNA sequences were determined by reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE) techniques for equine copper/zinc superoxide dismutase (Cu/Zn-SOD) and manganese superoxide dismutase (Mn-SOD) through the use of total RNA extracted from the testis of an adult Thoroughbred. The results revealed a protein coding region for equine Cu/Zn-SOD with bases totaling 465 bp, accompanied by an estimated 154 residues of amino acids. As for equine Mn-SOD, its coding region contained a total of 669 bp and an estimated 222 residues of amino acids. Further, the expression of Cu/Zn-SOD and Mn-SOD genes were confirmed in the equine tissues by RT-PCR and in situ hybridization.

Amino Acid Sequence↗
PubMed1999

Double high-dose chemotherapy supported by autologous transplantation of peripheral blood stem cells for treatment of an elderly patient with small-cell lung cancer.

We report a 62-year-old male with extensive disease small-cell lung cancer (SCLC) who was successfully treated with double high-dose chemotherapy supported by autologous peripheral blood stem cell transplantation (auto-PBSCT). This patient achieved a partial response with 3 cycles of induction chemotherapy. After the peripheral blood stem cell mobilization, two cycles of high-dose ICE regimen (ifosfamide 3,000 mg/m2 at days 1 to 5, carboplatin 400 mg/m2 at days 1, 3, 5, and etoposide 500 mg/m2 at days 1, 3, 5) could be given with further regression of the tumor and acceptable toxicities. This successful case suggests the feasibility of double high-dose ICE with auto-PBSCT in elderly patients with SCLC.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1999

Peripheral-type primitive neuroectodermal tumor arising in the tentorium. Case report.

The authors report the case of a peripheral primitive neuroectodermal tumor (PNET) arising in the tentorium in a 5-year-old boy who presented with frequent vomiting and mild palsy of the left abducent nerve. Following complete surgical excision of the tumor via a transpetrosal approach, the patient has thus far been disease free for 7 years. The tumor tissue was composed of small cells with uniform round nuclei and minimal identifiable cytoplasm. Homer-Wright rosettes were frequently observed. Immunohistochemical studies demonstrated a positive reaction to HBA-71, which recognizes the cell surface glycoprotein p30/32, a product of the MIC2 gene. Both the clinical and immunohistochemical characteristics of this tumor are consistent with a diagnosis of peripheral PNET, which is genetically distinct from the more common intracranial PNET.

12E7 Antigen↗
PubMed1999

Intraoperative electrooculographic monitoring of oculomotor nerve function during skull base surgery. Technical note.

Intraoperative monitoring techniques for protecting the integrity of the oculomotor nerves during skull base surgery have been reported by several investigators, all of which involved the use of electromyographic responses to extraocular muscles. However, these techniques have not yet become popular because of the complexity of the procedures. The authors report an extremely simple and far more reliable technique in which electrooculographic (EOG) monitoring is used. The oculomotor nerves were stimulated with a monopolar electrode during skull base exposure. The polarity of the EOG responses recorded with surface electrodes placed on the skin around the eyeball yielded precise information concerning the location and function of the oculomotor and abducent nerves. In addition, with the aid of continuous EOG monitoring that detected transient changes in the background waves, surgical procedures that might impinge on oculomotor nerve function could be avoided. The present technique has been used in eight patients with skull base tumors and with it, the authors have achieved excellent results.

Electrooculography↗
PubMed1999

Improved efficiency of hypervolemic therapy with inhibition of natriuresis by fludrocortisone in patients with aneurysmal subarachnoid hemorrhage.

OBJECT: To reduce the risk of ischemic complications in patients with subarachnoid hemorrhage (SAH), hypervolemic therapy is generally advocated. However, such conventional treatment cannot always ensure the maintenance of an effective intravascular volume expansion, because excessive natriuresis and osmotic diuresis occur after SAH. In this prospective study the authors examined the effects of inhibition of natriuresis with fludrocortisone acetate on intravascular volume expansion during hypervolemic therapy. METHODS: Thirty patients with SAH were randomized and divided into two groups: controls (Group 1, 15 patients) and patients treated with 0.3 mg/day of fludrocortisone (Group 2, 15 patients). In all patients sodium and fluid intake levels were in excess of maintenance requirements in an attempt to maintain a positive water balance and a central venous pressure (CVP) of 8 to 12 cm H2O. The mean sodium and water intake levels for 14 days after SAH were significantly reduced by fludrocortisone in Group 2 (487+/-34.52 mEq/day and 5159.2+/-249.29 ml/day, respectively; p<0.01) compared with Group 1 (634.2+/-42.86 mEq/day and 6611.7+/-365.67 ml/day). Fludrocortisone significantly reduced the urinary sodium excretion (p<0.01) and urine volume (p<0.01) in parallel, and effectively prevented a negative shift in the sodium as well as water balance (p<0.01). The serum sodium level tended to decrease in Group 1, reaching 135 mEq/L on average, but not in Group 2 (p<0.01). Hyponatremia in Group 1 was always observed at the optimal range of CVP values. A decrease in serum potassium level within the range of 2.8 to 3.5 mEq/L was transiently noted in 11 patients (73.3%) of Group 2, but was easily corrected. Possible side effects of fludrocortisone, such as pulmonary edema, were not encountered. CONCLUSIONS: Intravascular volume expansion in the presence of excessive natriuresis requires a large sodium and water intake and is often associated with hyponatremia. Inhibition of natriuresis with fludrocortisone can effectively reduce the sodium and water intake required for hypervolemia and prevent hyponatremia at the same time.

Adult↗
PubMed1999

[Aortic valve operations through an upper partial sternotomy].

The median sternotomy has been accepted as the most common approach to the heart, because this approach is easily opened and closed, and easy access to the entire heart is possible. Following the pioneering work by Cosgrove and colleagues of using a parasternal incision for aortic and mitral valve operations, several reports suggested that modified minimal access procedures are likely to be associated with reduced postoperative discomfort and faster recovery. Since July 1997, we have used an upper partial sternotomy and a limited skin incision for isolated aortic valve replacement (AVR) at our hospital. To demonstrate the benefits of this approach, we compared 14 AVR operations using our minimal access incision (group M) with 19 patients undergoing isolated AVR using a conventional sternotomy (group F). In the minimal access group of patients, a small skin incision was made from the second intercostal space to the fourth rib. The pectralis major and intercostal muscle was freed from the sternum, and then a transverse half sternotomy was made in the fourth intercostal space using a striker without injury to the right internal mammary artery. A median partial sternotomy from the supersternal notch to the level of the fourth intercostal space. Cardiopulmonary bypass was connected through the same access site to avoid cannulation of both groins. Conversion to median sternotomy was not necessary in any patient including reexploration for postoperative bleeding. There was no operative mortality, stroke, aortic dissection and perivalvular leaks due to technical factors. In group F, wound infection occurred in 1 patient. One patient in group M required reoperation to control postoperative bleeding. Although mean duration of operation, cardiopulmonary bypass, and cross clamp time in group M was not prolonged, the initiation of cardiopulmonary bypass and aortic crossclamp was delayed by difficulties of cannulations. The distance between the transverse sternotomy (lower edge of divided sternum) and the midpoint of aortic valve annulus was correlated with mean duration of cardiopulmonary bypass and cross clamp time. Our experience demonstrates that isolated AVR through an upper partial sternotomy allows the same quality operations as the full sternotomy, although more clinical experience is required to clarify the benefits of this approach. Excellent exposure of the aortic valve through a partial sternotomy may be attained, if an adequate approach can be selected by the position of aortic valve.

Aortic Valve↗
PubMed1999

Age- and sex-related differences of plasma activated factor VII levels in children.

Although the majority of factor VII (FVII) circulates in the zymogen form, low levels of activated factor VII (FVIIa) exist in plasma and play an important role in the initiation of tissue factor-induced coagulation. It has been reported that the concentrations of hemostatic components in children and adults are different. Here, we investigated the age- and sex-related differences of FVIIa and FVII antigen (FVIIag) levels in children at age of 10 (n = 123; males: n = 62; females: n = 61), and 13 (n = 105; males: n = 47: females: n = 58), and compared these levels with those of young adults (mean +/- SD of age: 29.6+/-6.0 years). In males, there was not a significant difference between the FVIIIa levels of 10-year-old children and 13-year-old children, but the FVIIa levels in adult controls were significantly higher than those in children. In females, the FVIIa levels in 13-year-old children were significantly higher than that in 10-year-old children, but there was not a significant difference between 13-year-old children and adults. Thus, our study showed that plasma FVIIa levels were lower in children than in adults, and the increase of FVIIa level was earlier in females than in males.

Adolescent↗