PubMed Health⌕ Search

Biomedical subjects

H Masumoto

Publications and source records attributed to H Masumoto.

At least 19 recordsLinked to original sources
PubMed1998

A helix-turn-helix structure unit in human centromere protein B (CENP-B).

CENP-B has been suggested to organize arrays of centromere satellite DNA into a higher order structure which then directs centromere formation and kinetochore assembly in mammalian chromosomes. The N-terminal portion of CENP-B is a 15 kDa DNA binding domain (DBD) consisting of two repeating units, RP1 and RP2. The DBD specifically binds to the CENP-B box sequence (17 bp) in centromere DNA. We determined the solution structure of human CENP-B DBD RP1 by multi-dimensional 1H, 13C and 15N NMR methods. The CENP-B DBD RP1 structure consists of four helices and has a helix-turn-helix structure. The overall folding is similar to those of some other eukaryotic DBDs, although significant sequence homology with these proteins was not found. The DBD of yeast RAP1, a telomere binding protein, is most similar to CENP-B DBD RP1. We studied the interaction between CENP-B DBD RP1 and the CENP-B box by the use of NMR chemical shift perturbation. The results suggest that CENP-B DBD RP1 interacts with one of the essential regions of the CENP-B box DNA, mainly at the N-terminal basic region, the N-terminal portion of helix 2 and helix 3.

Amino Acid Sequence↗
PubMed1998

[Combined rupture of trachea and esophagus following blunt trauma--a case report].

A 49-year-old man was involved in a motor vehicle crash and was admitted to a local hospital. The following day, he was transferred to our hospital because of worsening dyspnea. Initial examination revealed no subcutaneous emphysema, and chest computed tomography (CT) demonstrated no mediastinal air. A left thoracentesis tube was placed for pneumothorax, which reduced the patient's respiratory distress. He had a persistent, productive cough, which worsened when he drank water. A repeat chest CT on the fifth hospital day revealed a tracheo-esophageal fistula. Bronchoscopy and esophagoscopy confirmed the diagnosis. He underwent repair of the trachea and esophagus. The ruptured membraneous portion of the trachea was closed with interrupted sutures and covered with pedicled pericardial flap. The perforated anterior esophageal wall was sutured in layers and reinforced with a fifth intercostal muscle flap. A gastrostomy tuve was placed for feeding access. Within 6 weeks, the patient recovered completely.

Esophagus↗
PubMed1998

Construction of YAC-based mammalian artificial chromosomes.

To construct a mammalian artificial chromosome (MAC), telomere repeats and selectable markers were introduced into a 100 kb yeast artificial chromosome (YAC) containing human centromeric DNA. This YAC, which has a regular repeat structure of alpha-satellite DNA and centromere protein B (CENP-B) boxes, efficiently formed MACs that segregated accurately and bound CENP-B, CENP-C, and CENP-E. The MACs appear to be about 1-5 Mb in size and contain YAC multimers. Structural analyses suggest that the MACs have not acquired host sequences and were formed by a de novo mechanism. The accurate segregation of the MACs suggests they have potential as vectors for introducing genes into mammals.

Animals↗
PubMed1998

Ligation plus low-volume sclerotherapy for high-risk esophageal varices: comparisons with ligation therapy or sclerotherapy alone.

Endoscopic variceal ligation therapy (EVL) seems to be a more effective and safer method than endoscopic injection variceal sclerotherapy (EVS) for treating bleeding esophageal varices. However, EVL may entail a higher recurrence rate than EVS. The aim of this study was to examine whether EVL combined with low-dose EVS reduced the recurrence rate compared to treatment with EVL alone and reduced the complication rate compared to treatment with EVS alone. In this prospective study, 59 patients with cirrhosis and high-risk (F2 or F3, red color sign ++ or ) esophageal varices were enrolled. They were randomly assigned to an EVS group (n = 18), an EVL group (n = 20), and a combination EVL plus low-dose EVS group (n = 21). After the eradication of varices, follow-up endoscopic examinations were carried out for 24 months to determine the recurrence of varices. Complications, e.g., severe dysphagia, fever, renal dysfunction and pleuritis were also evaluated. The recurrence-free rate was significantly lower in the EVL group (60% at 24 months) than in either the EVS group (90%, P < 0.05) or the combination group (88%, P < 0.05). However, no significant difference was found between the EVS group and the combination group. The complication rate was significantly higher in the EVS group (50%) than in either the EVL group (5%, P < 0.01) or the combination group (10%, P < 0.01). The combination therapy seems to be useful to improve the benefits achieved with EVL alone and to reduce the harmful effects induced by EVS alone. EVL plus low-volume EVS is advisable in the treatment of high-risk esophageal varices.

Aged↗
PubMed1998

Results of omental flap transposition for deep sternal wound infection after cardiovascular surgery.

OBJECTIVE: Our experience with omental flap transposition in the treatment of deep sternal wound infections is reviewed here with an emphasis on efficacy, risk factors for in-hospital mortality rates, and long-term results. SUMMARY BACKGROUND DATA: Even with improvements in muscle and omental flap transposition, the timing of closure and the surgical strategy are controversial. METHODS: Forty-four consecutive patients with deep sternal wound infections were treated using the omental flap transposition from 1985 through 1994. The strategies included debridement with delayed omental flap transposition or single-stage management, which consisted of debridement of the sternal wound and omental flap transposition. Methicillin-resistant Staphylococcus aureus was cultured from more than 50% of the wounds. A logistic regression analysis was used to identify the predictors of in-hospital death after omental flap transposition. RESULTS: There were seven (16%) in-hospital deaths. Univariate analysis demonstrated that hemodialysis and ventilatory support at the time of omental flap transposition were significantly associated with in-hospital mortality rates (p = 0.0023 and p = 0.0075, respectively). Thirty-seven patients whose wounds healed well were discharged from the hospital. Two patients with cultures positive for methicillin-resistant Staphylococcus aureus had recurrent sternal infections. Patients without positive methicillin-resistant Staphylococcus aureus cultures had good long-term results after reconstructive surgery. CONCLUSIONS: Transposition of an omental flap is a reliable option in the treatment of deep sternal wound infections, unless the patients require ventilatory support or hemodialysis at the time of transposition.

Adult↗
PubMed1998

Sld2, which interacts with Dpb11 in Saccharomyces cerevisiae, is required for chromosomal DNA replication.

The DPB11 gene, which genetically interacts with DNA polymerase II (epsilon), one of three replicative DNA polymerases, is required for DNA replication and the S phase checkpoint in Saccharomyces cerevisiae. To identify factors interacting with Dbp11, we have isolated sld (synthetically lethal with dpb11-1) mutations which fall into six complementation groups (sld1 to -6). In this study, we characterized SLD2, encoding an essential 52-kDa protein. High-copy SLD2 suppressed the thermosensitive growth defect caused by dpb11-1. Conversely, high-copy DPB11 suppressed the temperature-sensitive growth defect caused by sld2-6. The interaction between Sld2 and Dpb11 was detected in a two-hybrid assay. This interaction was evident at 25 degreesC but not at 34 degreesC when Sld2-6 or Dpb11-1 replaced its wild-type protein. No interaction between Sld2-6 and Dpb11-1 could be detected even at 25 degreesC. Immunoprecipitation experiments confirmed that Dpb11 physically interacts with Sld2. sld2-6 cells were defective in DNA replication at the restrictive temperature, as were dpb11-1 cells. Further, in dpb11-1 and sld2-6 cells, the bubble-shaped replication intermediates formed in the region of the autonomously replicating sequence reduced quickly after a temperature shift. These results strongly suggest the involvement of the Dpb11-Sld2 complex in a step close to the initiation of DNA replication.

Amino Acid Sequence↗
PubMed1997

Portal-hypertensive gastropathy develops less in patients with cirrhosis and fundal varices.

BACKGROUND/AIMS: The aim of this prospective study was to examine the association of portal-hypertensive gastropathy and fundal varices in patients with cirrhosis. METHODS: We carried out an endoscopic observation in 476 patients with cirrhosis (study 1), including 62 patients undergoing endoscopic obliteration of esophageal varices (study 2). In study 1, patients were classified into five subgroups: no esophagofundal varices (n=119), small esophagofundal varices (n=127), dominant esophageal varices (n=177), dominant fundal varices (n=27), and large esophagofundal varices (n=26). The severity of liver dysfunction was assessed by Pugh-Child classification: class A (n=222), class B (n=200), and class C (n=54). In study 2, two groups, poorly developed fundal varices (n=50) and well developed fundal (n=12), were distinguished and the follow-up endoscopic examinations were performed on the basis of 3-month intervals for 2 years. In each study, the severity of portal-hypertensive gastropathy was scored: 0 (absent), 1 (mild), 2 (severe), and 3 (bleeding). RESULTS: Study 1: One-way ANOVA showed that both variceal pattern and Pugh-Child class significantly influenced portal-hypertensive gastropathy score. However, two-way ANOVA indicated that variceal pattern was the only significant variable. Portal-hypertensive gastropathy score was significantly higher in patients with dominant esophageal varices than in either patients with no esophagofundal varices or patients with small esophagofundal varices. In contrast, portal-hypertensive gastropathy score in patients with dominant fundal varices was similar to that in patients with no esophagofundal varices and was significantly lower compared with that in patients with dominant esophageal varices. Furthermore, portal-hypertensive gastropathy score was significantly lower in patients with large esophagofundal varices than in patients with dominant esophageal varices. Study 2: After the obliteration of esophageal varices, portal-hypertensive gastropathy score in patients with poorly developed fundal varices became significantly higher at 3-, 6-, 9-months while it was not modified in patients with well developed fundal varices during the follow-up period. Furthermore, the integrated incremental change in portal-hypertensive gastropathy score during the first 1-year follow-up period was significantly lower in patients with well developed fundal varices than in patients with poorly developed fundal varices. CONCLUSIONS: These results indicate that both spontaneous and obliteration-induced portal-hypertensive gastropathy lesions develop less in patients with cirrhosis and fundal varices.

Endoscopy, Digestive System↗
PubMed1997

Value of Doppler ultrasound parameters of portal vein and hepatic artery in the diagnosis of cirrhosis and portal hypertension.

OBJECTIVES: This prospective study was designed to assess the sensitivity and specificity of Doppler ultrasound parameters in the diagnosis of cirrhosis and portal hypertension. METHODS: Portal and hepatic arterial Doppler ultrasound was performed on 76 patients with cirrhosis and esophageal varices and on 73 age- and sex-matched controls. The parameters evaluated were portal venous velocity and hepatic arterial pulsatility index. The liver vascular index was calculated as the ratio of portal venous velocity to hepatic arterial pulsatility index. RESULTS: Portal venous velocity was significantly lower (11.0 +/- 2.4 vs 15.9 +/- 2.8 cm/s, p < 0.001) and hepatic arterial pulsatility index was significantly higher (1.28 +/- 0.18 vs 0.95 +/- 0.17,p < 0.001) in patients than in controls. Thus, the liver vascular index was significantly lower in patients than in controls (8.7 +/- 2.1 vs 17.2 +/- 4.3 cm/s, p < 0.001). The sensitivity and specificity of these parameters in the detection of cirrhosis and portal hypertension was then analyzed with the receiver operating characteristic curve. The best cut-off values were considered to be 13 cm/se of portal venous velocity and 1.1 of hepatic arterial pulsatility index, showing a sensitivity and specificity of 83, 85, 84, and 81%, respectively. The best cut-off value of the liver vascular index was 12 cm/s with a sensitivity and specificity of 97 and 93%, respectively. CONCLUSIONS: The liver vascular index is a high sensitive and specific Doppler ultrasound parameter in the diagnosis of cirrhosis and portal hypertension.

Biopsy↗
PubMed1996

Kinetic study of the reaction of ebselen with peroxynitrite.

The second-order rate constant for the reaction of ebselen with peroxynitrite (ONOO-) is (2.0+/-0.1) X 10(6) M(-1) s(-1) at pH > or = 8 and 25 degrees C, 3-4 orders of magnitude higher than the rate constants observed for cysteine, ascorbate, or methionine. The activation energy is relatively low, 12.8 kJ/mol. This is the fastest reaction of peroxynitrite observed so far. It may allow Se-containing compounds to play a novel role in the defense against peroxynitrite, one of the important reactive species generated during inflammatory processes.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1996

Selenium-containing compounds protect DNA from single-strand breaks caused by peroxynitrite.

Peroxynitrite (ONOO-/ONOOH) is a powerful oxidant that can induce mutations and cause single-strand breaks in plasmid supercoiled DNA. The selenium-containing compound ebselen rapidly reacts with peroxynitrite. Therefore, ebselen [2-phenyl-1,2-benzisoselenazol-3(2H)-one] and other selenium-containing molecules, selenomethionine and selenocystine, were studied as agents protecting DNA from single-strand breaks induced by peroxynitrite. Selenomethionine and selenocystine protected DNA from single-strand breaks more effectively than their sulfur analogs, methionine and cystine, and they also were more effective than glutathione or the hydroxyl radical scavenger mannitol. These results suggest that selenium-containing compounds can protect DNA from damage caused by peroxynitrite.

Cystine↗
PubMed1996

Effect of vasopressin on esophageal varices blood flow in patients with cirrhosis: comparisons with the effects on portal vein and superior mesenteric artery blood flow.

BACKGROUND/AIMS: Vasopressin reduces portal pressure which may be due to decreased portal inflow. However, it remains unclear whether vasopressin is able to selectively reduce esophageal varices blood flow. The aim of this study was to address this question. METHODS: Fifteen patients with cirrhosis and esophageal varices were included in this prospective study. Portal vein and superior mesenteric artery flow velocity were measured with a percutaneous echo-Doppler. Esophageal varices flow velocity was measured using a transesophageal echo-Doppler technique. Mean arterial pressure and heart rate were also recorded. These measurements were performed at baseline condition and 15 min after observer blind drug administration. In this study, two groups, six patients receiving placebo and nine patients receiving 0.3 U/min of vasopressin, were randomized according to the coded number. RESULTS: Placebo administration had no effect on systemic and splanchnic circulation. In contrast, vasopressin administration increased mean arterial pressure (p < 0.05) associated with a bradycardia (p < 0.01). In splanchnic circulation, vasopressin decreased portal vein (-32 +/- 3%, p < 0.01), superior mesenteric artery (-30 +/- 2%, p < 0.01), and esophageal varices flow velocity (-48 +/- 5%, p < 0.01). When the magnitude of these reductions was compared, ANOVA showed a significant difference (p < 0.01). Furthermore, the reduction in esophageal varices flow velocity was significantly higher than that in portal vein flow velocity (p < 0.01) and that in superior mesenteric artery flow velocity (p < 0.01). CONCLUSIONS: These data support the view that vasopressin is able to selectively reduce esophageal varices blood flow. This effect, in addition to its well-established portal pressure reducing action, may play a role in its therapeutic efficacy in the treatment of variceal bleeding.

Aged↗
PubMed1996

Centromere protein B of African green monkey cells: gene structure, cellular expression, and centromeric localization.

Centromere protein B (CENP-B) is a centromeric DNA-binding protein which recognizes a 17-bp sequence (CENP-B box) in human and mouse centromeric satellite DNA. The African green monkey (AGM) is phylogenetically closer to humans than mice and is known to contain large amounts of alpha-satellite DNA, but there has been no report of CENP-B boxes or CENP-B in the centromere domains of its chromosomes. To elucidate the AGM CENP-B-CENP-B box interaction, we have analyzed the gene structure, expression, biochemical properties, and centromeric localization of its CENP-B. The amino acid sequence deduced from the cloned AGM CENP-B gene was established to be highly homologous to that of human and mouse CENP-B. In particular, the DNA binding and homodimer formation domains demonstrated 100% identity to their human and mouse counterparts. Immunoblotting and DNA mobility shift analyses revealed CENP-B to be expressed in AGM cell lines. As predicted from the gene structure, the AGM CENP-B in the cell extracts exhibited the same DNA binding specificity and homodimer forming activity as human CENP-B. By indirect immunofluorescent staining of AGM mitotic cells with anti-CENP-B antibodies, a centromere-specific localization of AGM CENP-B could be demonstrated. We also isolated AGM alpha-satellite DNA with a CENP-B box-like sequence with CENP-B affinity. These results not only prove that CENP-B functionally persists in AGM cells but also suggest that the AGM genome contains the recognition sequences for CENP-B (CENP-B boxes with the core recognition sequence or CENP-B box variants) in centromeric satellite DNA.

Amino Acid Sequence↗
PubMed1996

Hepatic artery hemodynamic responsiveness to altered portal blood flow in normal and cirrhotic livers.

PURPOSE: To compare hepatic artery hemodynamic response to altered portal blood flow in normal and cirrhotic livers. MATERIALS AND METHODS: The portal blood flow and hepatic artery pulsatility index were measured by means of duplex ultrasound before and after subjects (eight control subjects and 10 cirrhotic patients) ingested a 500-kcal mixed-liquid meal and during intravenous infusion of vasopressin at a rate of 0.3 U/min (nine control and nine cirrhotic subjects). The hepatic artery buffer index (ratio of maximum change from baseline in hepatic artery pulsatility index to maximum change from baseline in portal blood flow) was also calculated. RESULTS: Meal consumption increased the portal blood flow and hepatic artery pulsatility index in all subjects. The hepatic artery buffer index, however, was significantly lower in cirrhotic than in control subjects (0.67 min/L +/- 0.06 [standard error of the mean] vs 1.54 min/L +/- 0.20, respectively; P < .01). Vasopressin infusion decreased the portal blood flow and hepatic artery pulsatility index in all subjects. Again, the hepatic artery buffer index was significantly lower in cirrhotic than in control subjects (0.28 min/L +/- 0.07 vs 0.50 min/L +/- 0.04, respectively; P < .05). CONCLUSION: Hepatic artery vascular responsiveness to altered portal blood flow is blunted in cirrhotic livers.

Fasting↗
PubMed1996

Postprandial splanchnic hemodynamic response in patients with cirrhosis of the liver: evaluation with "triple-vessel" duplex US.

PURPOSE: To investigate the effect of a meal on splanchnic circulation in patients with cirrhosis of the liver. MATERIALS AND METHODS: Ten adult patients with cirrhosis and 10 adult control subjects (mean age, 54 years) underwent duplex ultrasonography. Flow volumes of the portal vein, superior mesenteric artery, splenic artery, and collateral vessels (difference between the splanchnic inflow [the sum of the superior mesenteric arterial and the splenic arterial blood flows] and the portal venous blood flow) were measured before and after a meal every 15 minutes for 60 minutes. Integrated post-prandial changes (the sum of the changes at each time point) were also calculated. RESULTS: Portal venous blood flow increased after the meal in control subjects (P < .01) and patients (P < .01). The integrated postprandial change in the portal venous blood flow was lower in patients than in control subjects (P < .05). Superior mesenteric arterial blood flow increased after the meal in control subjects (P < .01) and patients (P < .01); the integrated postprandial change in the superior mesenteric arterial blood flow was similar. In the two groups, splenic arterial blood flow remained unchanged after the meal. Collateral blood flow increased after the meal in patients (P < .01). CONCLUSION: Postprandial portal hyperemia is mainly due to mesenteric arterial vasodilation; reduced postprandial portal hyperemia in patients with cirrhosis is attributable to portocollateral runoff.

Adult↗
PubMed1996

[Diagnostic value of high N-isopropyl-p-[123I] iodoamphetamine (IMP) uptake in brain tumors].

The diagnostic value of high N-isopropyl-p-[123I] iodoamphetamine (123I-IMP) uptake in histologically proven intracranial tumors was evaluated in 54 patients with both early (15-35 min after injection) and delayed (4 hours) SPECT before treatment. Higher uptake in the tumor compared with normal cerebral cortex was observed in early scans in all of the five patients with primary intracranial malignant lymphoma, in two of 16 meningiomas, two of seven astrocytomas, one of three pituitary adenomas, and one central neurocytoma. Among these 11 cases all the malignant lymphomas showed persistent high uptake in delayed scans, whereas other tumors showed decreased uptake in delayed scans. This persistent high 123I-IMP uptake was characteristic of primary intracranial malignant lymphomas and was useful in the diagnosis of intracranial malignant lymphoma.

Adult↗