PubMed Health⌕ Search

Biomedical subjects

Masaki Shimizu

Publications and source records attributed to Masaki Shimizu.

At least 19 recordsLinked to original sources
PubMed2006

Rituximab therapy for Epstein-Barr virus-related chronic hepatitis following living donor kidney transplantation.

A patient who underwent living donor kidney transplantation was infected with Epstein-Barr virus (EBV) that resulted in persistent EBV infection and EBV-associated chronic hepatitis, determined by abnormally elevated anti-EBV antibody titers and high frequency of EBV-infected B lymphocytes. Despite decreases in immunosuppressant doses, persistent EBV infection and chronic hepatitis persisted for several years. Therapy using anti-CD20 monoclonal antibody (rituximab) virtually eliminated peripheral B lymphocytes and EBV-encoded small RNA 1 (EBER-1)-positive cells. Moreover, hepatic enzyme levels normalized and histological findings indicated marked improvement in hepatic inflammation. Although peripheral CD20(+) B lymphocyte and EBER-1-positive cell levels began to increase 4 months after the end of therapy, the number of EBER-1-positive cells remained very low, and liver function test results remained within normal ranges. The present case illustrates the significance of early diagnosis, monitoring of viral load, and vigorous management of EBV-related disorders associated with organ transplantation.

Adolescent↗
PubMed2006

Cytomegalovirus-associated protracted diarrhoea in an immunocompetent boy.

AIM: Cytomegalvirus (CMV) gastroenteritis is rarely described in immunocompetent children. We describe here an immunocompetent 1-year-old boy with CMV-associated protracted diarrhoea and discuss the pathogenesis of CMV infection of the gastrointestinal tract. METHODS: Immunohistochemical study was performed using a gastric and duodenal tissue of this patient. Furthermore, the detection of CMV-DNA in stool and urine samples was performed by polymerase chain reaction method. RESULTS: CMV infection was proven by the detection of CMV-DNA in stool and urine samples and CMV-positive cells in the immunoperoxidase preparation from gastroduodenal biopsy. The biopsy specimens showed severe chronic active gastroduodenitis with numerous CD3+ T cells and CD68+ macrophages. CONCLUSIONS: We speculated from these findings that CMV invasion of the mucosal layer induced an intense immune response characterised by massive infiltration of activated T-cells and macrophages in this patient. Although the pathogenesis of CMV-associated gastroenteritis in immunocompetent hosts remains generally unknown, immune mechanism may play some roles in generating the chronic inflammatory lesions.

Antigens, CD↗
PubMed2006

Morbidity and mortality of infants born at the threshold of viability: ten years' experience in a single neonatal intensive care unit, 1991-2000.

BACKGROUND: The purpose of the present paper was to evaluate the mortality and morbidity of infants born at 22-24 weeks gestation. METHODS: A total of 78 infants born at 22-24 weeks gestation, who were admitted between January 1991 through December 2000, were retrospectively studied. RESULTS: Seventy-one of 78 infants were enrolled in the present study. One year survival rates at 22, 23 and 24 weeks were 40.0% (2/5), 61.1% (11/18), and 50.0% (24/48), respectively. Failure of response to surfactant and air leak were associated with death in infants born at 23 weeks gestation. Low Apgar score, intraventricular hemorrhage (> or =III), and sepsis were correlated with death in infants born at 24 weeks gestation. The handicap rates of survivors born at 22, 23, and 24 weeks gestation were 100, 36.4, and 26.1%, respectively. CONCLUSIONS: The present study indicates that infants born at 22 weeks gestation, in whom pulmonary structure is established, that is, a viable lung that can exchange gas with exogenous surfactant, have a chance to survive, but neurological outcome is still poor. Every possible effort should be made to extend gestation beyond 22 weeks.

Female↗
PubMed2006

In vitro short-time killing activity of povidone-iodine (Isodine Gargle) in the presence of oral organic matter.

In order to estimate the clinical efficacy of a povidone-iodine oral antiseptic (PVP-I) on oral bacterial infectious diseases, we studied the effect of oral organic matter on the in vitro killing activity of PVP-I. In addition, we compared the in vitro short-time killing activity of PVP-I with those of other oral antiseptics using mouth-washing and gargling samples collected from healthy volunteers. When any of the mouth-washing and gargling samples was used, the standard (0.23-0.47%) or lower concentrations of PVP-I killed methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa, including multidrug-resistant strains, within 15-60 s in the presence of oral organic matter. 0.02% benzethonium chloride (BEC) and 0.002% chlorhexidine gluconate (CHG) did not show effects against MRSA and P. aeruginosa (including multidrug-resistant strains) in mouth-washing and gargling samples even after 60 s. The above-mentioned results show that the in vitro killing activity of the standard concentration of PVP-I was hardly affected by the oral organic matter and that a mouth-washing or gargling solution containing PVP-I has a stronger bactericidal activity than BEC and CHG. Although mouth-washing and gargling samples were obtained from healthy individuals in this study, PVP-I may be used for protection against infections in patients with various diseases, if proper concentrations and usage are encouraged.

Anti-Infective Agents↗
PubMed2006

Inhaled nitric oxide therapy might reduce the need for hyperventilation therapy in infants with persistent pulmonary hypertension of the newborn.

AIM: To determine whether inhaled nitric oxide might reduce the need for excessive respiratory alkalosis to maintain systemic oxygenation in infants with persistent pulmonary hypertension of the newborn (PPHN). MATERIALS AND METHODS: A retrospective historical cohort study of 34 infants with PPHN with oxygenation index (OI) of 25 or more, including 19 infants without inhaled nitric oxide (i-NO) therapy (control group) and 15 infants with inhaled nitric oxide therapy (i-NO group) was performed. The initial dose of 10 ppm of i-NO was administered and no responders received the maximum dose of 25 ppm. We evaluated the mortality rate and the change of OI index and PaCO(2) during the first 6 days. RESULTS: There were no significant differences in characteristics between groups. Two of 15 in the i-NO group and 6 of 19 infants in the control group died during the first 48 h. Baseline OI, PaCO(2) and arterial pH were similar in the two groups. OI in the i-NO group was significantly higher than in the control group between 12 and 96 h. PaCO(2) in the i-NO group was higher than in the control group between 24 and 144 h. CONCLUSION: i-NO therapy for PPHN might improve systemic oxygenation without excessive hypocapnia. However there was no reduction in duration of ventilation support or oxygen supply.

Administration, Inhalation↗
PubMed2005

Stereoselective cross-coupling reaction of 1,1-Diboryl-1-alkenes with electrophiles: a highly stereocontrolled approach to 1,1,2-triaryl-1-alkenes.

Palladium-catalyzed cross-coupling reaction of 1,1-diboryl-1-alkenes with aryl and alkenyl iodides was found to proceed stereoselectively, giving rise to the corresponding mono-coupled product as a single diastereomer with E-configuration. Second coupling of the initial product with another aryl iodide affords diverse triarylalkenes in their stereochemically pure form. This highly stereoselective approach for triarylalkenes allows one to synthesize both diastereomers in one pot from 1,1-diboryl-1-alkenes.

Alkenes↗
PubMed2005

Glomerular proteinuria induces heme oxygenase-1 gene expression within renal epithelial cells.

To clarify the patterns of heme oxygenase-1 (HO-1) production within the human kidney, we examined HO-1 mRNA expression in various renal diseases and compared the patterns with those of HO-1 protein expression and these data with the clinical features. The degrees of hematuria and proteinuria and the levels of urinary N-acetyl-beta-D-glucosaminidase (NAG), beta(2)-microglobulin (beta(2)-mg), and creatinine were determined. In situ hybridization and immunohistochemical studies were performed to evaluate HO-1 expression. HO-1 mRNA was detectable within tubular, glomerular, and Bowman's epithelial cells and infiltrating macrophages. Within the proximal tubuli, there was a correlation between expression of HO-1 protein and mRNA, but the intensity of HO-1 mRNA expression was much less than expected from the levels of protein. In contrast, both HO-1 protein and mRNA were expressed at significant levels within distal tubuli. Furthermore, there was no correlation with both expressions within distal tubuli. HO-1 mRNA expression within tubular, glomerular, and Bowman's epithelial cells tended to be more intense with greater degrees of proteinuria. However, there was little correlation between the intensity of HO-1 mRNA expression and the degree of hematuria, NAG, and beta(2)-mg. HO-1 plays important roles in maintaining renal functions by protecting renal epithelial cells from glomerular proteinuria, which can become a cause of oxidative stress. Furthermore, from the different expression pattern of HO-1 gene between within the proximal tubuli and within the distal tubuli, renal expression of HO-1 is regulated in a segment-specific manner, with HO-1 thereby playing distinct roles in different segments of the nephron to maintain renal functions.

Acetylglucosaminidase↗
PubMed2004

Modern synthetic methods for fluorine-substituted target molecules.

Fluorine has come to be recognized as a key element in materials science: in heat-transfer agents, liquid crystals, dyes, surfactants, plastics, elastomers, membranes, and other materials. Furthermore, many fluorine-containing biologically active agents are finding applications as pharmaceuticals and agrochemicals. Progress in synthetic fluorine chemistry has been critical to the development of these fields and has led to the invention of many novel fluorinated molecules as future drugs and materials. As a result of the electronic effects of fluorine substituents, fluorinated substrates and reagents often exhibit unusual and unique chemical properties, which often make them incompatible with established synthetic methods. Thus, the problem of how to control the unusual properties of compounds with fluorine substituents deserves much attention, so as to promote the design of facile, efficient, and environmentally benign methods for the synthesis of valuable organofluorine targets.

Chemistry, Agricultural↗
PubMed2004

Evolution of acute focal bacterial nephritis into a renal abscess.

Acute focal bacterial nephritis (AFBN) is a localized bacterial infection of the kidney presenting as an inflammatory mass without frank abscess formation, which may represent a relatively early stage of renal abscess. The pathogenesis of AFBN is thought to be hematogenous infection or ascending infection from the lower urinary tract. For the majority of children, the pathogenesis may be related to ascending infection, because pre-existing malformative uropathy, especially vesicoureteral reflux (VUR), is common in pediatric patients. Few clinical reports have demonstrated the evolution of this condition into renal abscess in children. We report a girl with AFBN associated with VUR that evolved into a renal abscess despite appropriate intravenous antibiotic therapy. We undertook serial radiological observation of its evolution. It is important to differentiate AFBN from renal abscess because the management of the two entities may be different, and follow-up studies are indispensable to determine appropriate therapy.

Abscess↗
PubMed2003

Bilateral phrenic-nerve paralysis treated by thoracoscopic diaphragmatic plication in a neonate.

Traditionally, diaphragmatic plication (DP) is performed via a thoracotomy that includes incision of the lower intercostal muscles, which are involved in respiratory movement. This may adversely affect ventilation by causing deterioration of respiratory function and making ventilation less efficient. These problems do not occur with thoracoscopic DP (TDP), since the lower intercostal muscles are left intact. We describe a full-term newborn infant with bilateral phrenic-nerve paralysis (PNP) who was treated by TDP and conclude that this method may be effective in the treatment of PNP even in small infants.

Diaphragm↗
PubMed2003

gem-Silylborylation of an sp carbon: novel synthesis of 1-boryl-1-silylallenes.

[reaction: see text] Novel synthesis of 1-boryl-1-silylallenes involving gem-silylborylation of 3-chloro- or 3-alkoxyalkyn-1-yllithiums with (dimethylphenylsilyl)(pinacolato)borane has been established. The reaction proceeds via 1,2-migration of the silyl group from the negatively charged boron atom of an intermediary borate complex to the terminal acetylenic carbon and is accelerated by the addition of chlorotrimethylsilane in the case that methanesulfonyloxy is employed as a leaving group. Furthermore, axially enantioenriched products could be prepared from mesylates of optically active propargylic alcohols.

Journal Article↗
PubMed2003

Selective protection of renal tubular epithelial cells by heme oxygenase (HO)-1 during stress-induced injury.

BACKGROUND: The renal pathology of human heme oxygenase (HO)-1 deficiency is characterized by advanced tubulointerstitial injury, whereas the glomerular structures are affected little. These facts suggest that the renal tubuli are dependent on intrinsic HO-1 production for their survival under oxidative stresses. METHODS: We compared the patterns of HO-1 expression by primary cultured human mesangial cells (HMCs) and renal proximal tubular epithelial cells (HRPTECs) in vitro. Furthermore, the cytoprotective roles of HO-1 induced in these cells were evaluated by stress-induced cytotoxicity assays. HO-1 expressions in HRPTECs and HMCs were evaluated by immunoblotting, and by reverse transcriptase (RT) and/or real time polymerase chain reaction (PCR). RESULTS: In HRPTECs, both HO-1 mRNA expression and protein production peaked at around 12 h and persisted until 24 h after hemin stimulation. In contrast, HO-1 mRNA expression and protein production by HMCs peaked at 4 h and 6 h respectively, and the levels declined rapidly, being undetectable at 24 h. The peak level of HO-1 expression was significantly higher in HRPTECs than in HMCs. Oxidative stress-induced cell injury in HRPTECs was significantly reduced when HO-1 production had been induced prior to the culture. In contrast, HO-1 induction had little cytoprotective effect on HMCs. Tin protoporphyrin (SnPP), an inhibitor of HO function, significantly reversed the cytoprotection by HO-1. CONCLUSION: These data suggest that HRPTECs are more susceptible to oxidative stress and are significantly more dependent on HO-1 for protection against noxious stimuli than HMCs. Collectively, these results indicate that HO-1 is an important protective factor for kidney tissue, in particular, renal tubular epithelial cells.

Cells, Cultured↗
PubMed2003

[Relationship between arbekacin-susceptibility and aminoglycoside-resistant gene of methicillin-resistant Staphylococcus aureus (MRSA)].

The susceptibility to arbekacin (ABK) of methicillin-resistant Staphylococcus aureus (MRSA) was investigated to find out how it related to aac(6')/aph(2") gene. In 49 isolates of MRSA for which MIC of ABK ranged from 0.125 to 64 micrograms/ml, the MICs of ABK for 38 strains carrying aac(6')/aph(2") gene were widely distributed from 0.25 to 64, whereas those for 11 strains without that gene were all < or = 0.5 microgram/ml. Residual rate of ABK activity was higher than that of gentamicin after the reaction with each crude enzyme preparation extracted from 3 isolates of MRSA, carrying aac(6')/aph(2") and aad(4',4") genes. Furthermore, 97 strains of MRSA isolated at Kanagawa prefecture in Japan in 1999 were all sensitive to ABK, although 28 strains of them carried aac(6')/aph(2") gene. These results showed that ABK resistance was not necessarily related to carrying aac(6')/aph(2") gene in clinical isolates of MRSA.

Acetyltransferases↗
PubMed2002

Follow-up study of auditory brainstem responses in infants with high unbound bilirubin levels treated with albumin infusion therapy.

BACKGROUND: Several authors reported that there was a close relationship between unbound bilirubin concentrations and abnormal results of auditory brainstem responses. Full-term infants with high-unbound bilirubin concentrations who were treated with human albumin were followed to evaluate their hearing abilities by using auditory brainstem responses. METHODS: Fifty-eight infants (gestational age, 39.4 +/- 1.4 weeks; birthweight, 3,245 +/- 435 g) with high unbound bilirubin concentrations (> or = 0.9 micro g/dL) were treated with intensive phototherapy. Twenty infants (control group) received only phototherapy, while 38 others (albumin-treated group) were also given i.v. human albumin administration (1 g/kg bodyweight) during the first 2 h of phototherapy. The follow-up study of auditory brainstem responses was carried out at 6 and 12 months of age. Development quotient tests were carried out at 18 months of age. RESULTS: Abnormalities of auditory brainstem response were detected in three infants in the albumin-treated group and six infants in the control group at 6 months. Two infants in the albumin-treated group and four infants in the control group had improved at 12 months. The results of the follow-up study at 18 months of age in the both groups were normal with development quotient >85. No patients with hearing disability and cerebral palsy were clinically detected at the age of 2 years. CONCLUSION: The results suggest that albumin priming might be effective for decreasing the rate of auditory brainstem response abnormalities at 6 months.

Bilirubin↗
PubMed2002

[In vitro short-term bactericidal activity and accumulation of NM394, the active metabolite of prulifloxacin, for Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa: comparison with ciprofloxacin, levofloxacin, and gatifloxacin].

The in vitro short-term bactericidal activity and accumulation of NM394, the active metabolite of prulifloxacin, was compared with those of ciprofloxacin (CPFX), levofloxacin (LVFX) and gatifloxacin (GFLX), using Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. Of the 4 fluoroquinolones examined, NM394 accumulated to the highest concentration in all three strains. The order of concentration of the fluoroquinolones accumurated in S. aureus 209P JC-1, E. coli NIHJ JC-2 and P. aeruginosa PAO1 were NM394 >> CPFX > GFLX > or = LVFX. The accumulation of fluoroquinolones into bacterial cells correlated with their MICs of the drugs for E. coli and P. aeruginosa, whereas there was no correlation between the accumulation and MICs of the drugs for S. aureus. We also studied the reduction of viable cells after addition of each fluoroquinolones to clarify relationship between the short-term bactericidal activity and the accumulation of the quinolones. The short-term bactericidal activity of NM394 against S. aureus 209P JC-1, E. coli NIHJ JC-2 and P. aeruginosa PAO1 were stronger than those of CPFX, LVFX and GFLX when compared at the same concentration. In conclusion, the strong short-term bactericidal activity of NM394 may be attributed to its high accumulation in bacterial cells.

Anti-Infective Agents↗