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M Shioda

Publications and source records attributed to M Shioda.

At least 37 records · Page 2Linked to original sources
PubMed1993

Initiation of DNA synthesis in a high molecular weight fraction of Xenopus egg extract.

Xenopus egg extract was fractionated by gel-filtration column chromatography and DNA synthetic activity was examined using double-stranded DNA as a template. The major activity eluted had an apparent molecular mass of about 300 kDa. Product analyses showed that de novo DNA synthesis occurs with formation of replication bubbles, thereby suggesting that this fraction catalyzes the initiation of DNA replication. Activities of DNA polymerase alpha-primase and DNA helicase overlapped with the DNA synthetic activity, but the elution profiles of the enzymes differed from that of the DNA synthetic activity. Therefore, this 300-kDa fraction may contain a component which differs from the above enzymes yet is essential for initiation of DNA replication.

Animals↗
PubMed1993

Isolation of a new species of Physarum lysophosphatidic acid, PHYLPA, and its effect on DNA polymerase activity.

A new species of lysophosphatidic acid was isolated from myxoamoebae of a true slime mold, Physarum polycephalum, and structural studies were performed. The purified substance was subjected to nuclear magnetic resonance spectroscopy (NMR), infrared spectroscopy (IR), fast atom bombardment mass spectroscopy (FAB/MS), alkaline hydrolysis and tandem mass spectroscopy (MS/MS), and the results suggested this substance to be lysophosphatidic acid composed of a cyclic phosphate and cis-11,12-methylene octadecanoic acid. The effects of the LPA on DNA polymerases were studied and compared with the effects of PHYLPA, which had been isolated as a specific inhibitor of eukaryotic DNA polymerase alpha (6). It showed a specific inhibitory activity on eukaryotic DNA polymerase alpha, but no activity on the repair-type, or mitochondrial DNA polymerases.

Animals↗
PubMed1993

Inhibition of cell proliferation by a unique lysophosphatidic acid, PHYLPA, isolated from Physarum polycephalum: signaling events of antiproliferative action by PHYLPA.

The unique Physarum lysophosphatidic acid, PHYLPA, having a cyclopropane in the fatty acid moiety and a cyclic phosphate at C-2 and C-3 positions of the glycerol, inhibited proliferation of human fibroblast cells, TIG-3 and TIG-7, which were cultured in a chemically defined (serum-free) medium. The cells at S- and M-phases proceeded to G2- and G1-phases, respectively, and most of cells were arrested at G1- or G2-phase during PHYLPA treatment. The growth was recovered when PHYLPA was removed from the medium. In the presence of serum, PHYLPA did not show obvious inhibitory effects, indicating the existence of a factor(s) which neutralizes the antiproliferative activity of PHYLPA. PHYLPA elicited an increase in 3',5'-cyclic adenosine monophosphate (cAMP) in a biphasic fashion in fibroblast cells. It also elicited inositol phosphate accumulation, as well as a transient rise in cytoplasmic free Ca2+ ion.

Animals↗
PubMed1993

Modulation of DNA synthesis by microtubule-associated protein 2 in the nuclear matrix isolated from Physarum polycephalum.

The mechanism of stimulation of DNA synthesis by microtubule-associated protein 2 (MAP2) was examined in the nuclear matrix isolated from Physarum polycephalum. Porcine brain MAP2 stimulated DNA synthesis by the matrix with exogenous templates, but not with endogenous templates. Kinetic analyses showed that MAP2 decreases the Km of the matrix for deoxyribonucleoside triphosphates. Comparison of the Km values of active- and latent-type DNA replication machineries of Physarum suggested a possible role for MAPs or MAP-like proteins in DNA replication.

Animals↗
PubMed1992

Inhibition of eukaryotic DNA polymerase alpha with a novel lysophosphatidic acid (PHYLPA) isolated from myxoamoebae of Physarum polycephalum.

A specific inhibitor of DNA polymerase alpha was isolated from the lipid fraction prepared from myxoamoebae of a true slime mold, Physarum polycephalum. The purified substance was subjected to structural studies by fast atom bombardment mass spectroscopy, infrared spectroscopy, and two-dimensional nuclear magnetic resonance spectroscopy. The structure of this substance was thereby suggested to be a novel lysophosphatidic acid (LPA) composed of cyclic phosphate and cyclopropane-containing hexadecanoic acid. Then we named this substance PHYLPA (Physarum LPA). PHYLPA inhibited more than 80% of the affinity-purified calf thymus DNA polymerase alpha activity at a concentration of 10 micrograms/ml (approximately 20 microM). Inhibition was observed for DNA polymerase alpha but not for DNA polymerase beta or gamma from various eukaryotic species, nor did it inhibit DNA polymerase I from E. coli. From kinetic analyses, the inhibition was considered to be caused by the interaction of PHYLPA with the template DNA.

Animals↗
PubMed1992

Chromosomal structure of the halophilic archaebacterium Halobacterium salinarium.

The chromosomal structure of the extremely halophilic archaebacterium Halobacterium salinarium was examined. Sheared chromosomes prepared from the bacteria in the late exponential phase were separated into two peaks (peaks I and II) by sucrose gradient centrifugation, suggesting that the chromosomes consist of two parts differing in quality. The UV spectra of peaks I and II resembled those of DNA and eukaryotic chromatin, respectively. Electron microscopic observations revealed that the major component of peak I was protein-free DNA, while the major components of peak II were rugged thick fibers with a diameter of 17 to 20 nm. The rugged fibers basically consisted of bacterial nucleosome-like structures composed of DNA and protein, as demonstrated in experiments with proteinase and nuclease digestion. Whole-mount electron microscopic observations of the chromosomes directly spread onto a water surface revealed a configuration in which the above-described regions were localized on a continuous DNA fiber. From these results it is concluded that the H. salinarium chromosome is composed of regions of protein-free DNA and DNA associated with nucleosome-like structures. Peaks I and II were predominant in the early exponential phase and stationary phase, respectively; therefore, the transition of the chromosome structure between non-protein-associated and protein-associated forms seems to be related to the bacterial growth phase.

Animals↗
PubMed1992

[A case of paraesophageal bronchogenic cyst with esophageal communication].

A case of mediastinal bronchogenic cyst communicating with the esophagus was reported. Previously, only 2 cases have been reported in the available literature. A 34-year-old man was admitted with a cystic mass communicating with the esophagus which was demonstrated on a barium study. Operation was performed with a suspect of esophageal diverticulum or congenital cyst with esophageal communication. At right thoracotomy, a mass measuring 6.0 x 5.0 cm with a well-defined patent communication to the esophagus was resected. It was a monolocular cyst containing a small amount of viscous mucus. Histologically, the cyst lined by a ciliated columnar epithelium, and it was diagnosed as a bronchogenic cyst because of the presence of the mucous glands, smooth muscle tissue and cartilage. This is the first case report of mediastinal bronchogenic cyst with esophageal communication appeared in the Japanese literature.

Adult↗
PubMed1991

Stimulation of DNA polymerase alpha activity by microtubule-associated proteins.

Microtubule-associated protein 2 (MAP2) isolated from porcine brains stimulated the activity of DNA polymerase alpha immunopurified from calf thymus or human lymphoma cells, in a dose-dependent manner. This stimulation was pronounced when activated DNA or poly(dA).(dT)10 was used as the template-primer. DNA polymerase alpha bound to a MAP2-immobilized column, whereas preincubation of the enzyme with unbound MAP2 prevented binding to the column. These events suggested that a physical binding occurred between the polymerase and MAP2. Kinetic analyses revealed that MAP2 decreased the Km value of the polymerase for deoxyribonucleotides, irrespective of the species of template-primer. A concomitant increase in Vmax was observed; however, the extent of the increase depended on the species of template-primer. MAP2 also decreased the Km value of the polymerase for template-primers when activated DNA of poly(dA).(dT)10 was used as the template-primer. Product analyses showed that MAP2 did not significantly alter the processivity of the polymerase and the increment of Vmax is considered to be due to an increase in the frequency of initiation of DNA synthesis. The stimulation by MAP2 occurred specifically in the activity of DNA polymerase alpha, but not DNA polymerases beta, gamma, and I from Escherichia coli. Other MAPs, tau and 190-kDa MAP, could substitute for MAP2. Thus, the specific stimulation of DNA polymerase alpha by MAPs supports the notion of a possible involvement of MAPs or MAP-like proteins in DNA replication, in vivo.

Animals↗
PubMed1991

[Studies on right ventricular performance in surgical treatment for primary lung cancer--especially in changes of right ventricular ejection fraction in acute phase].

In surgical treatment for lung cancer, increase of right ventricular afterload associated with decrease of pulmonary vascular bed after lung resection is serious problem in acute phase. Intensive care is necessary for the patients having major surgery, especially in aged. Until now, we have studied on pre and post operative extravascular lung water (EVLW) in addition to measurement of conventional hemodynamic changes on right ventricular afterload. And then, we have discussed when we should start to care intensively for degradation of compensatory hyperdynamic change. According to percent exchanges (delta %) between pre and post operative measurement, we established following criterion 1) delta %HR greater than 150% 2) delta SVI less than 60% 3) delta % PARI greater than 200% 4) observed postoperative EVLW greater than predicted postoperative EVLW. Furthermore, we investigated the correlation with these criterion and RVEF in 14 patients using a rapid computerized thermodilution method on right cardiac function in acute phase. We found that 1) changes of RVEF seem to depend on endsystolic volume 2) RVEF decreased just after operation and then slowly increased until 48 hours 3) PARI elevated to 194 +/- 117% in average at 6 to 24 hours showing significant inversed linear correlation to changes of RVEF (R = -0.54). The patients having prolonged elevation of PARI showed degradation of cardiac output and RVEF. RVSWI showed compensative acceleration gradually with increased right ventricular afterload.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

[Simplified prediction of postoperative lung function by plain chest roentgenogram in patients with primary lung cancer--in correlation to postoperative respiratory complications].

For the purpose of simplification of prediction of postoperative lung function, we studied to predict lung function by analizing the frontal and lateral view of chest plain roentgenogram and investigate the correlation to respiratory complication on 111 patients with lung cancer. According to TNM classification of lung cancer, prediction was performed as follows. Predicted postoperative lung function = [(42-number of resected subsegments)/(42-number of occupied subsegments)] x preoperative VC or FEV1.0. In this formula, 42 was the number of functioning subsegments of whole lung (right: 22, left: 20), and then preoperative occupied subsegments was ordered by T factor, where T1 lesion in lung field was prescribed as 1 subsegment and T2 was more than 2 subsegments respectively in plain chest roentgenogram. And also, on the patients having hilar lesions, it was required to calculate the number of subsegments in atelectasis, peripheral obstructive pneumonia and/or partial emphysematous change due to intrabronchial lesions. There was uniformly positive correlations in VC (R = 0.7949) and FEV1.0 (R = 0.8235) of the patients studied respectively. The patients having pneumonectomy showed tendency of over estimation, on the other hand, the patients having resection of a few segments showed under estimation. To predict the postoperative respiratory condition, we calculated the predicted post-operative %VC and %FEV1.0 for predicted preoperative normal VC and FEV1.0. Above the al, we tried to investigate the correlation with predicted postoperative %VC, %FEV1.0 and postoperative respiratory complications.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Studies on increased sputum after bronchoplastic surgery for lung cancer in correlation with hemodynamics and extravascular lung water].

In surgical treatment for lung cancer, large amount of intrabronchial sputum and secretion was occasionally encountered in patients, especially underwent bronchoplastic surgery. It has been discussed as causes which was affected from transection of pulmonary branches of vagal nerve and bronchial arteries. So we have measured pre- and postoperative hemodynamics and extravascular lung water (EVLW) at the bedside, as to investigate the correlation with formyl sputum and increase of right ventricular afterload which was presumed by lung resection and bronchoplasty. Respiratory complication was classified by the incidence of forced bronchial toilet in acute phase. Seven patients were investigated. Three of seven showed white sputum which was difficult to excrete. EVLW was 9.91 +/- 2.12 ml/kg in average before operation and then showed a tendency to increase within 102 +/- 29% of percent exchange (delta %) between pre- and postoperation. As to comparison of delta % of EVLW in acute period, the patients underwent bronchoplastic surgery showed a tendency to increase rather than the patients underwent lobectomy. According to former studies, we found the uniform correlation R = 0.7075 between observed EVLW and predicted postoperative EVLW estimated by prediction of residual functioning lung volume before operation. And also, the patients showing postoperative EVLW more than predicted EVLW before operation had a tendency to increase amount of sputum. Furthermore, concerning hemodynamic changes, pulmonary arterial resistance index (PARI) elevated to 196 +/- 165% (83-515%) in average associated with increased right ventricular stroke work index (RVSWI) as a result of compensatory changes for increased right cardiac afterload.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

[Successful re-reconstruction for complete disruption of the right main bronchus by blunt chest trauma].

A 22 year-old man was brought to our hospital about twenty-three minutes following a high-speed motorbicycle accident in which he had blunt chest trauma. He was in severe respiratory distress with marked dyspnea and restless with extensive subcutaneous emphysema involving anterior chest wall, cervical and bilateral inguinal regions. A chest X-ray revealed bilateral pneumothorax involving mediastinal emphysema and also fracture of right submandibular and clavicula. In spite of orotracheal intubation and insertion of bilateral chest tube, continuous air leak and pneumothorax did not improve. Bronchoscopy revealed the disruption of mucosa of the right main bronchus at the bifurcation. Emergency right thoracotomy was performed and there was the complete disruption of the right main bronchus. Anastomosis of the right main bronchus with circumferential resection was undertaken on May 30, 1987 about two hours after trauma. About three months after reconstruction, bronchoscopic examination revealed stomal stenosis with deformation of tracheobronchial cartilage and granulation. The stenosis showed severe irregularity by deformed cartilage and thickened scar, so widening by Nd-YAG laser vaporization was inadequate in effect. Seven months after first reconstruction, we performed re-reconstructive operation, right upper sleeve lobectomy with partial resection of carcina and right wall of trachea for scar with severe deformation of cartilage. Following the operation, the patient suffered from sepsis with pneumonitis accompanied by lung edema. This complication was treated successfully. We considered that acute pneumonitis was caused by reventilation with increase of perfusion after tracheobronchial reconstruction. Consequently, we thought it important to treat such patients with long term IPPB postoperatively with adequate medication for respiratory system.

Accidents, Traffic↗
PubMed1989

DNA synthesis by the isolated nuclear matrix from synchronized plasmodia of Physarum polycephalum.

Nuclear matrices were isolated from plasmodia of a true slime mold, Physarum polycephalum, and the DNA synthetic activity in vitro was examined. These matrices isolated in S-phase catalyzed DNA synthesis requiring Mg2+, deoxyribonucleoside 5'-triphosphates and ATP, without exogenous templates. The activity changed during S-phase with the rate of in vivo DNA replication. Product analysis by gel electrophoresis revealed that the matrices produced Okazaki fragments. These results suggest that DNA synthesis partially reflects in vivo DNA replication. DNA synthesis was sensitive to aphidicolin, heparin and N-ethylmaleimide, indicating involvement of the alpha-like DNA polymerase of Physarum. Exogenous addition of activated DNA stimulated DNA synthesis 4-10-fold and suggested that only some of the existing enzymes are involved in endogenous DNA synthesis. Matrices isolated in G2-phase were also associated with a similar DNA synthetic activity, but they did not produce Okazaki fragments in vitro. It is, therefore, concluded that nuclear matrices are associated with alpha-like DNA polymerase throughout the cell cycle, and that some of the enzymes participate in in vivo DNA replication in S-phase; thus, DNA replication is possibly controlled by this process. The relationship between DNA synthetic activities by the isolated nuclei and matrices was also discussed.

Adenosine Triphosphate↗
PubMed1989

Microtubule-associated protein-2 stimulates DNA synthesis catalyzed by the nuclear matrix.

Microtubule-associated protein-2 (MAP-2) isolated from porcine brains stimulated DNA synthesis catalyzed by the nuclear matrix isolated from Physarum polycephalum in the presence of activated DNA as exogenous templates. The degree of the stimulation depended on the amount of the nuclear matrix, but not on that of the template. MAP-2 also stimulated DNA polymerase alpha activity solubilized from nuclei, but not DNA polymerase beta activity. These results suggest that MAP-2 stimulates DNA synthesis by interacting with the putative DNA replication machinery including DNA polymerase alpha bound to the matrix. Similar stimulation occurred in the nuclear matrix isolated from HeLa and rat ascites hepatoma cells, which strongly suggests that MAP-2 is involved in the control of DNA replication in eukaryotic cells.

Animals↗