Eosinophilic peritonitis with colon cancer: a case report.

BACKGROUND: Eosinophilic gastrointestinal disorders (EGIDs) are a rare group of inflammatory disorders that can occur anywhere along the gastrointestinal tract, from the esophagus to the rectum. In particular, those with malignant or benign tumors are extremely rare. CASE PRESENTATION: A 62-year-old man was referred to our hospital with a chief complaint of abdominal fullness. The peripheral white blood cell count was 19,400/µL, and the eosinophil count was 13,300/µL. Abdominal computed tomography showed massive ascites. Cytology of the ascitic fluid showed a large amount of eosinophils and no malignancy. Upper and lower gastrointestinal endoscopies were performed on the suspicion of EGIDs, and colon cancer with no other abnormalities was found. The biopsies of the cancer lesions and non-cancer lesions also showed significant differences in eosinophil counts per high-power field (HPF) between the cancer and non-cancer lesions (median 77.5 [IQR 52-115] vs. 40.5 [35-56]/HPF, P < 0.05). Exploratory laparoscopy showed cloudy massive ascites and thickening of the mesentery. Pathological examination of the mesentery showed a large amount of eosinophils (median 177.5 [IQR 91-227]/HPF) and no malignancy. Based on these findings, it was suspected that the massive ascites due to eosinophilic peritonitis could be associated with colon cancer. Steroid administration resulted in immediate disappearance of the ascites, and laparoscopic left hemicolectomy was safely performed 6 weeks after steroid administration. CONCLUSION: This report presented a case of eosinophilic peritonitis that could be related to colon cancer. Exploratory laparoscopy was useful to detect the cause of ascites. The possibility that eosinophilic peritonitis was associated with colon cancer is discussed based on the histopathological findings.

The increased frequency of methicillin-resistant Staphylococcus aureus with low MIC of beta-lactam antibiotics isolated from hospitalized patients.

Methicillin-resistant Staphylococcus aureus (MRSA) causes severe infectious diseases and can be life-threatening in healthcare-settings. MRSA is classified into health-care associated (HA)-MRSA strains and community acquired (CA)-MRSA strains based on genotype and phenotype. CA-MRSA has been reported to show the lower minimal inhibitory concentration (MIC) of some antibiotics as compared to HA-MRSA. Recently, the prevalence of CA-MRSA has been increased in worldwide. CA-MRSA is isolated not only from the healthy individuals in a community but also from the patients in healthcare settings. However, the changing trend in frequency of HA-MRSA and CA-MRSA in the hospital setting is not clear. Therefore, we analyzed the trend of MIC to speculate the frequency of HA-MRSA and CA-MRSA in the facility. Moreover, gene mutations were evaluated on resistant gene loci with next generation sequencer. The frequency of strains with low MIC of beta-lactam antibiotics was gradually increased in isolated MRSA strains from the hospitalized patients. Whole genome analysis revealed the frequency of gene mutation was also decreased in some resistant loci, such as blaZ and blaR1. These findings highlight the changing trend of MRSA strains isolated from hospitalized patients.

L-Arginine L-Glutamate Enhances Gastric Motor Function in Rats and Dogs and Improves Delayed Gastric Emptying in Dogs.

Amino acids are not only constituents of proteins, but also have multiple physiologic functions. Recent findings have revealed that ingested amino acids either activate luminal receptors or are metabolized, causing physiologic reactions in the gastrointestinal (GI) tract. We examined the effect of oral L-arginine L-glutamate (ArgGlu), a pharmaceutical amino acid salt used i.v. for the treatment of hyperammonemia, on gastric motor function in rats and dogs. Gastric emptying was determined using phenol red and 13C-breath test methods, whereas gastric relaxation was determined using the barostat method. ArgGlu (10-30 mg/kg, p.o.) dose-dependently promoted gastric emptying in rats. This effect was dependent on vagus nerve activation and comparable to that of the prokinetic mosapride. Intragastric ArgGlu (3-30 mg/kg intragastrically) also dose-dependently enhanced adaptive relaxation of rat stomachs, which was negated not by vagotomy of gastric branches, but by pretreatment with N omega-nitro-L-arginine methyl ester (20 mg/kg i.v.), a nitric oxide synthase inhibitor. Its relaxing effect on the stomach was also confirmed in dogs and was equally as efficacious as treatment with sumatriptan (1-3 mg/kg s.c.). ArgGlu (30 mg/kg p.o.) significantly reduced the half gastric emptying time in clonidine-induced delayed gastric emptying of solids in dogs, and its effect was comparable to that of cisapride (3 mg/kg p.o.). This study demonstrated that the pharmaceutical ingredient ArgGlu, currently used i.v., enhanced gastric motor function when administered orally, suggesting that it could be a new oral medicine indicated for treatment of upper GI hypofunction or dysfunction like functional dyspepsia.

[Molecular epidemiology of the Methicillin-resistant Staphylococcus aureus(MRSA) by the internal transcribed spacer PCR (ITS-PCR) method and the phage open reading frame typing (POT) method].

Methicillin-resistant Staphylococcus aureus (MRSA) is the most common causative bacteria of hospital acquired infection, and should be rapidly identified for infection control. For this purpose, in our hospital, the PCR electrophoresis patterns of spacer regions (ITS: internal transcribed spacers) (ITS-PCR) are combined with a toxigenicity assay to establish a strain identification method for outbreak surveillance. In the present study, the usefulness of this method was evaluated in comparison with the POT (phage-open reading frame typing) method. One hundred MRSA strains isolated from inpatients in our hospital between April 2011 and March 2012 were classified into 25 patterns using the ITS-PCR method combined with a toxigenicity assay. The strains could be classified into 46 patterns using the POT method. ITS-PCR type 22 strain producing enterotoxin C and toxic shock syndrome toxin-1 could be further classified into 7 patterns using the POT method. In the outbreak of the type 22 strain, cross-infection could be excluded by additional analysis using the POT method, providing more precise information on strain identification. We identified that some strains of the same POT type consisted of different ITS-PCR types or toxigenicities. Therefore, these results suggest that the combination of ITS-PCR method plus toxigenicity assay with POT method may be a useful technique of MRSA typing.

[Trends for the etiology of infective endocarditis at our hospital these 5 years].

The aim of this study is to evaluate characteristics of infective endocarditis for 5 years at Kanazawa University Hospital. Retrospectively, we investigated 39 patients diagnosed as infective endocarditis at our hospital from 2006 to 2010 based on blood culture and/or rejected cardiac specimens. Of 39 patients with infective endocarditis, 27 were male and 12 were female. Mean age was 55.4 years and 69% patients were older than 50 years. The frequent underlying presumed diseases were cardiac diseases. Vegetation was mainly observed at mitral valve and aortic valve. Streptococcus species [14 cases (36%)] and Staphylococcus species [12 cases (31%)] were common pathogens. In Streptococcus species, the critical cause was mostly presumed to be associated with dental procedure and oral cavity. In Staphylococcus species, intravascular device and soft tissue infection were also frequently presumed. Frequency of chronic kidney disease and infection around valve were higher in Staphylococcus species than those observed in Streptococcus species [12 cases (100%) vs. 7 cases (50%); p < 0.05, 6 cases (50%) vs. 1 case (7%); p < 0.05]. Our results suggested that the etiology of patients with Staphylococcus species infection increased in number among patients suffering from infective endocarditis at our hospital.

Does stringent restrictive annuloplasty for functional mitral regurgitation cause functional mitral stenosis and pulmonary hypertension?

BACKGROUND: It remains controversial whether restrictive mitral annuloplasty (RMA) for functional mitral regurgitation (MR) can induce functional mitral stenosis (MS) that may cause postoperative residual pulmonary hypertension (PH). METHODS AND RESULTS: One hundred eight patients with left ventricular (LV) dysfunction and severe MR underwent RMA with stringent downsizing of the mitral annulus. Systolic pulmonary artery pressure (PAP) and mitral valve performance variables were determined by Doppler echocardiography prospectively and 1 month after RMA. Fifty-eight patients underwent postoperative hemodynamic measurements. Postoperative echocardiography showed a mean pressure half-time of 92 ± 14 ms, a transmitral mean gradient of 2.9 ± 1.1 mm Hg, and a mitral valve effective orifice area of 2.4 ± 0.4 cm(2), consistent with functional MS. Doppler-derived systolic PAP was 32 ± 8 mm Hg, which correlated weakly with the transmitral mean gradient (ρ=0.23, P=0.02). Postoperative cardiac catheterization also showed significant improvements in LV volume and systolic function, pulmonary capillary wedge pressure, cardiac index, and systolic PAP; the latter was associated with LV end-diastolic pressure [standardized partial regression coefficient (SPRC)=0.51], pulmonary vascular resistance (SPRC=0.47), cardiac index (SPRC=0.37), and transmitral pressure gradient (SPRC=0.20). In a multivariate Cox proportional hazard model, postoperative PH (systolic PAP >40 mm Hg), but not mitral valve performance variables, was strongly associated with adverse cardiac events. CONCLUSIONS: RMA for functional MR resulted in varying degrees of functional MS. However, our data were more consistent with the residual PH being caused by LV dysfunction and pulmonary vascular disease than by the functional MS. The residual PH, not functional MS, was the major predictor of post-RMA adverse cardiac events.

Discovery and evaluation of selective N-type calcium channel blockers: 6-unsubstituted-1,4-dihydropyridine-5-carboxylic acid derivatives.

A structure-activity relationship study of 6-unsubstituted-1,4-dihydropyridine and 2,6-unsubstituted-1,4-dihydropyridine derivatives was conducted in an attempt to discover N-type calcium channel blockers that were highly selective over L-type calcium channel blockers. Among the tested compounds, (+)-4-(3,5-dichloro-4-methoxy-phenyl)-1,4-dihydro-pyridine-3,5-dicarboxylic acid 3-cinnamyl ester was found to be an effective and selective N-type calcium channel blocker with oral analgesic potential.

[Antimicrobial susceptibilityof clinical isolates of aerobic gram-negative bacteria in 2008].

We determined MICs of antibacterial agents against 1145 clinical strains of aerobic Gram-negative bacteria (22 species) isolated at 16 Japanese facilities in 2008. MICs were determined using mostly broth microdilution method and antibacterial activity was assessed. Strains producing extended-spectrum beta-lactamases (ESBL) accounted for 3.8% of Escherichia coli, 2.6% of Klebsiella pneumoniae, 6.8% of Klebsiella oxytoca, 5.5% of Proteus mirabilis and 1.8% of Proteus vulgaris. ESBL produced strains were 6.8% at K. oxytoca that increased compared with 3.2% and 5.5% at P. mirabilis that decreased compared with 18.8% in 2006. Among Haemophilus influenzae, 61.7% that decreased compared with 67.7% in 2006, equaled 58.7% in 2004, were strains when classified by penicillin-binding protein 3 mutation. Against Pseudomonas aeruginosa, the activity of most antibacterial agents was similar to that in 2006. Although two antibacterial agents that tobramycin showed an MIC90 of 1 microg/mL and doripenem showed an MIC90 of 4 microg/mL against P. aeruginosa have potent activity. Of all P. aeruginosa strains, 4.3% were resistant to six agents of nine antipseudomonal agents, that decreased compared to 12.2% in 2004 and 5.7% in 2006. Against other glucose-non-fermentative Gram-negative rods, the activity of most antibacterial agents was similar to that in 2006.

[Antimicrobial susceptibility of clinical isolates of aerobic gram-positive cocci and anaerobic bacteria in 2008].

The activity of antibacterial agents against aerobic Gram-positive cocci (25 genus or species, 1029 strains) and anaerobic bacteria (21 genus or species, 187 strains) isolated from clinical specimens in 2008 at 16 clinical facilities in Japan were studied using either broth microdilution or agar dilution method. The ratio of methicillin-resistant strains among Staphylococcus aureus and Staphylococcus epidermidis was 59.6% and 81.2%, suggesting that resistant strains were isolated at high frequency. Vancomycin (VCM), linezolid (LZD) and quinupristin/dalfopristin (QPR/DPR) had good antibacterial activity against methicillin-resistant S. aureus and methicillin-resistant S. epidermidis, with MIC90s of < or = 2 microg/mL. The ratio of penicillin (PC) intermediate and resistant strains classified by mutations of PC-binding proteins among Streptococcus pneumoniae was 92.0% that was highest among our previous reports. Cefpirome, carbapenems, VCM, teicoplanin (TEIC), LZD and QPR/DPR had MIC90s of < or = 1 microg/mL against PC-intermediate and resistant S. pneumoniae strains. Against all strains of Enterococcus faecalis and Enterococcus faecium, the MICs of VCM and TEIC were under 2 microg/mL, and no resistant strain was detected, suggesting that these agents had excellent activities against these species. 15.9% of E. faecalis strains and 1.2% of E. faecium strains showed intermediate to LZD. 17.1% of E. faecium strains showed intermediate or resistant to QPR/DPR. Against all strains of Clostridium difficile, the MIC of VCM was under 1 microg/mL, suggesting that VCM had excellent activity. Carbapenems showed good activity against Clostridiales, Bacteroides spp., and Prevotella spp., but one strain of Bacteroides fragilis showed resistant to carbapenems. And so, the susceptibility of this species should be well-focused in the future at detecting continuously.

Rapid identification of gram-negative bacteria with and without CTX-M extended-spectrum ß-lactamase from positive blood culture bottles by PCR followed by microchip gel electrophoresis.

We evaluated the usefulness of PCR analysis of the 16S-23S rRNA gene internal transcribed spacer (ITS) and the CTX-M extended-spectrum ß-lactamase (ESBL) followed by microchip gel electrophoresis (MGE) for direct identification and CTX-M detection of Gram-negative bacteria (GNB) from positive blood culture bottles. Of 251 GNB isolated from blood cultures containing a single bacterium, 225 (90%) were correctly identified at the species level directly from positive blood culture bottles by comparing the ITS-PCR patterns of the sample strain with those of the control strains. There were no cases of incorrect identification. Limitations encountered included the inability to detect mixed cultures (four bottles) as well as some species (Enterobacter species and Klebsiella oxytoca) demonstrating identical ITS-PCR patterns. A total of 109 ESBL-producing isolates from various clinical materials obtained between January 2005 and December 2008 were examined for bla(CTX-M), bla(SHV), and bla(TEM) genes by PCR and sequences of PCR products. CTX-M ESBL was detected in 105 isolates, and SHV ESBL was detected in two isolates. The remaining two isolates (K. oxytoca) were shown to harbor bla(OXY.) Twenty (19%) of 104 Escherichia coli isolates from blood cultures were suspected to produce ESBL by the combination disk method, and these isolates were shown to harbor CTX-M ESBL by PCR-MGE. The results were obtained within 1.5 h at a calculated cost of $6.50 per specimen. In conclusion, simultaneous detection of ITS length polymorphisms and bla(CTX)-(M) by single PCR followed by MGE is useful for rapid, cost-effective, and reliable species-level identification of CTX-M ESBL-producing GNB responsible for bloodstream infections.

Asymmetric synthesis and biological evaluations of (+)- and (-)-6-dimethoxymethyl-1,4-dihydropyridine-3-carboxylic acid derivatives blocking N-type calcium channels.

An efficient asymmetric synthesis of 1,4-dihydropyridine derivatives is described. The key step is the stereoselective Michael addition using t-butyl ester of L-valine as a chiral auxiliary to achieve good ee (>95% for all the tested experiments) and moderate yield. With this method, (+)-4-(3-chlorophenyl)-6-dimethoxymethyl-2-methyl-1,4-dihydropyridine-3,5-dicarboxylic acid cinnamyl ester was obtained and was characterized as a promising N-type calcium channel blocker with improved selectivity over L-type compared to its (-)- and racemic isomers.

Restrictive mitral annuloplasty for functional mitral regurgitation: acute hemodynamics and serial echocardiography.

BACKGROUND: Long-term effects of restrictive mitral annuloplasty (RMA), especially on hemodynamics and left ventricular (LV) function in patients with functional mitral regurgitation (MR), have not been fully investigated. METHODS AND RESULTS: From 1999 to 2008, 44 patients with refractory heart failure and functional MR underwent RMA with stringent downsizing of the mitral annulus. Serial echocardiography was performed to evaluate LV function (reverse remodeling), estimated systolic pulmonary artery pressure (PAP) and mitral valve geometry at baseline and at discharge, and annually thereafter. Cardiac catheterization was performed at baseline, and at discharge to evaluate acute hemodynamic change. There were 3 early deaths, and the 5-year survival rate was 78 ± 8%. In 41 survivors the clinical symptoms, stratified according to New York Heart Association class, significantly improved after surgery. Postoperative cardiac catheterization showed significant unloading for left ventricle, as well as improvement in LV systolic function. Serial echocardiography showed that improvements in LV function and systolic PAP were sustained in the majority of patients. Multivariate Cox regression analysis identified preoperative pulmonary hypertension (systolic PAP>60 mm Hg) as the significant predictor for postoperative adverse cardiac events. CONCLUSIONS: RMA for functional MR resulted in sustained improvement of hemodynamics and LV function over time. Additional studies are needed to define the negative impact of preoperative pulmonary hypertension in patients with this condition.

Bonding of self-etching adhesives on dehydrated dentin.

PURPOSE: This study examined the effect of dentin pretreatment with acetone or ethanol on bonding of one-bottle self-etching vs two-step self-etching adhesives to evaluate the effect of hydration on bond strength. MATERIALS AND METHODS: The bond strengths of resins were measured using two one-bottle and two two-step selfetching adhesives that bonded to wet dentin (control), or acetone- or ethanol-pretreated dentin. Wet dentin is the normal substrate for bond testing, and in the pretreatment groups, 95% acetone or ethanol was applied to the dentin surface for 30 s before bonding. Weight of resin adhesives before and after evaporation was measured to evaluate the extent of the solvent contents in the adhesives. Furthermore, phase separation of adhesives was morophologically investigated by in situ light-microscopic observation to evaluate the hydrophilicity of the adhesive resins. RESULTS: The bond strengths of the acetone and ethanol groups for one-bottle adhesives were significantly greater than for the control (p < 0.05). However, significantly lower bond strengths were found in the pretreatment groups for the two-step self-etching adhesives (p < 0.05). CONCLUSION: The bond strength depended on the wetness of the bonding substrate for both adhesive groups, with a positive effect in bond strength for one-bottle adhesives and a negative effect for two-bottle self-etching adhesives. The acetone- or ethanol-pretreated dentin surfaces may provide an improved substrate for resin adhesion of hydrophilic self-etching adhesives such as one-bottle self-etching adhesives due to dentin dehydration.

[Clinical evaluation of rapid identification of bacteria from positive-testing blood culture bottles by internal transcribed spacer PCR].

Delays in diagnosis and initiation of treatment of severe infections such as sepsis greatly influence patient prognosis. Our laboratory introduced rapid identification of bacterial species by PCR for positive blood culture samples as a routine laboratory test since April 2008. We extracted DNA directly from positive blood culture bottles and amplified the internal transcribed spacer (ITS) region of pathogenic microorganisms by PCR in order to identify bacterial species from electrophoretic patterns of PCR products. Of 167 strains from 167 samples excluding three samples with polymicrobial organisms, 144 strains (86.2%) were correctly identified at species level and 17 strains (10.2%) at genus level. The time required between DNA extraction and bacterial identification was about one and one-half hours. In patients with MRSA sepsis, the time of initiation of treatments such as administration of anti-MRSA drugs and intravascular catheter removal has clearly become earlier with the introduction of ITS-PCR, resulting decreased mortality from 35.0% to 16.0%. Rapid identification of pathogens directly from blood culture bottles by ITS-PCR seems to be useful for appropriate treatment of severe infectious diseases.

Ten-years degradation of resin-dentin bonds.

The purpose of this study was to evaluate the durability of resin-dentin bonds in 10-yr water-storage testing. Resin-dentin bonded bulk specimens were prepared using six commercially available resin adhesives. The resin-dentin bonded specimens were stored in water for 24 h (control group) or for 10 yr (experimental groups). After each storage period, the specimens were sectioned to make specimen beams and then subjected to a microtensile bond test. After the bond test, fractured surfaces were examined by scanning electron microscopy (SEM). In addition, interfacial observation of silver nanoleakage was performed using the backscatter electron mode of SEM. The bond strengths of four of the six adhesive systems tested decreased significantly after 10 yr. However, no significant bond-strength reduction was recorded for the other two systems. The interfacial observations showed water tree propagation in the bonding resin layer as a typical morphological change after aging for five of the six adhesives tested. Water tree propagation may be a symptom of degradation in the resin bonding layer of resin-dentin bonds.

A simplified echocardiographic measurements of direct effects of restrictive annuloplasty on mitral valve geometry.

OBJECTIVE: The purpose of this study was to evaluate the direct effects of restrictive mitral annuloplasty on mitral valve geometry. METHODS: We studied 23 patients (mean age: 63 ± 5 years) with functional mitral regurgitation (moderate to severe) and advanced cardiomyopathy (ejection fraction: 25 ± 8%) with ischemic (n = 15) or nonischemic (n = 8) conditions, who underwent restrictive annuloplasty. We determined annular septal-lateral diameter, tenting height, tenting area, vertical length of coaptation of the mitral leaflets (coaptation length), and ratio of coaptation length to septal-lateral diameter (coaptation length index) at end-systole, before and after surgery, using transthoracic echocardiography. RESULTS: Annular septal-lateral diameter, tenting height, and tenting area were significantly decreased (34 ± 7 to 20 ± 5 mm, P < 0.05; 9 ± 4 to 5 ± 2 mm, P < 0.05; 210 ± 120 to 80 ± 50 mm(2) , P < 0.05, respectively), whereas coaptation length and coaptation length index were significantly increased (3.4 ± 1.3 to 6.5 ± 2.9 mm, P < 0.05; 0.11 ± 0.06 to 0.33 ± 0.15, P < 0.05, respectively). Spearman's rank correlation analysis revealed that these five variables had a statistically significant correlation with the degree of mitral regurgitation. Furthermore, stepwise regression analysis showed that coaptation length index, in contrast to coaptation length, was the most important correlate with the degree of mitral regurgitation. CONCLUSION: Our simplified parameters were useful for quantitative and geometrical descriptions of mitral valve geometry, and may also provide important information for developing a surgical strategy for functional mitral regurgitation.

Collagen adhesion gene is associated with bloodstream infections caused by methicillin-resistant Staphylococcus aureus.

OBJECTIVES: Methicillin-resistant Staphylococcus aureus (MRSA) causes hospital- and community-acquired infections. It is not clear whether genetic characteristics of the bacteria contribute to disease pathogenesis in MRSA infection. We hypothesized that whole genome analysis of MRSA strains could reveal the key gene loci and/or the gene mutations that affect clinical manifestations of MRSA infection. METHODS: Whole genome sequences (WGS) of MRSA of 154 strains were analyzed with respect to clinical manifestations and data. Further, we evaluated the association between clinical manifestations in MRSA infection and genomic information. RESULTS: WGS revealed gene mutations that correlated with clinical manifestations of MRSA infection. Moreover, 12 mutations were selected as important mutations by Random Forest analysis. Cluster analysis revealed strains associated with a high frequency of bloodstream infection (BSI). Twenty seven out of 34 strains in this cluster caused BSI. These strains were all positive for collagen adhesion gene (cna) and have mutations in the locus, those were selected by Random Forest analysis. Univariate and multivariate analysis revealed that these gene mutations were the predictor for the incidence of BSI. Interestingly, mutant CNA protein showed lower attachment ability to collagen, suggesting that the mutant protein might contribute to the dissemination of bacteria. CONCLUSIONS: These findings suggest that the bacterial genotype affects the clinical characteristics of MRSA infection.

Properties and reactivity of the adenosine radical generated by radiation-induced oxidation in aqueous solution.

The formation of oxidation products of DNA bases induced by hole injection into DNA duplexes is closely related to the characteristics of the radical species generated, especially those from purine bases possessing lower oxidation potentials than pyrimidines. To investigate the reactivities of adenosine base radicals generated from the radical cations of adenosine (Ado), we have conducted extensive pulse radiolysis and steady-state X-radiolysis investigations of Ado under the conditions generating oxidizing radical species such as the sulfate radical anion (SO(4)(-*)). Kinetic analysis of the transient absorption spectra demonstrated that the redox-neutral radical of adenosine [Ado(-H)(*)] decays via a homogeneous bimolecular reaction, recombines with an alkyl alcohol radical, or abstracts hydrogen from the phosphate ion, with rate constants of 2k = 4.2 x 10(8) M(-1) s(-1) and k = 6.4-8.5 x 10(8) and 10(3)-10(4) M(-1) s(-1), respectively. High-dose pulsed electron beam irradiation, which generates high concentrations of Ado(-H)(*) during the radiolysis, yielded 8-oxo-7,8-dihydroadenosine (8-oxo-Ado) with a G value of 0.018 x 10(-7) mol J(-1). It is thus proposed that the disproportionation of Ado(-H)(*) might lead to the formation of 8-oxo-Ado as a minor process, which is in addition to the widely accepted mechanism in which the addition of hydroxyl radical to Ado initiates its formation.

In vitro degradation of resin-dentin bonds with one-bottle self-etching adhesives.

The purpose of this study was to evaluate the durability of one-bottle self-etching adhesive during long-term water-storage testing. Resin-dentin bonded specimens were prepared using four commercially available one-bottle self-etching adhesives. The specimens were sectioned perpendicular to the adhesive interface to produce beam-shaped specimens that were stored in water for 24 h (control group) and 100, 200, and 300 d (experimental groups). After each storage period, the beams were subjected to a microtensile bond test. After the bond test, fractured surfaces were examined using a scanning electron microscope. In addition, interfacial observations of the silver tracer were performed using the secondary and back-scatter modes of the scanning electron microscope. The bond strength of all tested adhesives decreased significantly after 100 or more days in water. The interfacial observations showed an oxygen-inhibition zone as electron lucent in the adhesive-composite border in control specimens, displaying silver impregnation with breakage after aging. The deterioration of the oxygen-inhibition zone in the adhesive-resin composite junction resulted in a decrease in bond strength after 100 d in water for one-bottle self-etching adhesives.

Effect of dentinal water on bonding of self-etching adhesives.

This study examined the effect of dentinal water on bonding, comparing one-bottle and two-step self-etching adhesives using microtensile bond test and scanning electron microscope. The bond strength of resin to dentin was measured for wet dentin (control) and dry dentin substrates. Wet dentin is the normal substrate for bond testing, whereas dry dentin was dehydrated in a desiccator at different drying times (5 to 60 min) before bonding. After bond testing, the fractured surfaces were examined. Although no correlation was found for two-step self-etching adhesives, the bond strength of the dry-dentin was significantly increased with the increase in the drying-time for one-bottle adhesives. With increased drying-time, the amount of water-bubbles was decreased for one-bottle adhesives; however, no bubble formation was seen in two-step adhesives in any group. The hydrophilic resin adhesive may entrap the water from dentin by osmosis during and after bonding. This effect may depend on the "hydrophilicity" of adhesives.