[Evaluation of Low-contrast Detectability Using the Digital Phantom Creation Tool in the Late Arterial Phase to Detect Liver Mass Lesions].

PURPOSE: Late arterial phase images of SD 8, SD 10, and SD 12 were acquired in the 3-phase dynamic study of the liver in combination with hybrid iterative reconstruction. We evaluated the low-contrast detectability by adding a simulated tumor to these images and aimed to formulate a standard image quality. METHODS: We prepared images with and without signal for 60 series of 20 samples, each with 3 image quality types (total: 120 series). The continuous confidence method by 10 observers detected 60 simulated tumors. RESULTS: The detection sensitivities were 0.765, 0.785, and 0.260 for SD 8, SD 10, and SD 12, respectively (p<0.001) with no significantly different specificities, and the areas under the curve were 0.901, 0.892, and 0.616 (p<0.001), respectively. The simulated mass detection rates were 74.5%, 75.0%, and 21.5% for SD 8, SD 10, and SD 12, respectively (p<0.001), and the intraclass correlation coefficients, which indicate interobserver reliability, were 0.697 at SD 10 without signal, and SD 12 without a signal significantly dropped to 0.185. CONCLUSION: Therefore, SD 12 images increase the possibility of overlooking lesions. Hence, image quality in the late arterial phase should be SD 10 or less.

Nature of the liver volume depending on the gender and age assessing volumetry from a reconstruction of the computed tomography.

Although the liver is a regenerating organ, excessive loss of liver volume (LV) can cause fatal liver failure. It is unclear whether LV is correlated with age; however, it is known that liver function decreases with age. In addition, the gender-related role of LV remains unclear. This study aimed to investigate the changes in LV by age and gender. Between January and December 2018, 374 consecutive patients who underwent abdominal multidetector computed tomography (MDCT) for any abdominal examinations were enrolled. LV was evaluated using MDCT. The relationship between the LV and body mass index (BMI), body surface area (BSA), age, and gender was investigated. The modified LV (mLV) was calculated by a formula measured LV × 1.5/BSA. LV correlated to BSA more than to BMI in both the males (R: 0.559 vs. 0.416) and females (R: 0.479 vs. 0.300) in our study. Age was negatively correlated to LV and BSA, and correlated to LV more than to BSA in males (R: 0.546 vs. 0.393) and females (R: 0.506 vs. 0.385). In addition, the absolute slope between age and LV in the males was higher than that in the females (14.1 vs. 10.2, respectively). Furthermore, the absolute slope of age and mLV in the males was slightly higher than in the females (9.1 vs. 7.3, respectively). In conclusion, LV in the normal liver is correlated to age rather than the one in the diseased liver. Liver volume in the males decreased more with age than LV in the females.

Contribution of Neuropilin-1 in Radiation-Survived Subclones of NSCLC Cell Line H1299.

Non-small cell lung cancer (NSCLC) is an aggressive lung cancer accounting for approximately 85% of all lung cancer patients. For the patients with Stages IIIA, IIIB, and IIIC, the 5-year survival is low though with the combination with radiotherapy and chemotherapy. In addition, the occurrence of tumor cells (repopulated tumors) that survive irradiation remains a challenge. In our previous report, we subcloned the radiation-surviving tumor cells (IR cells) using the human NSCLC cell line, H1299, and found that the expression of neuropilin-1 (NRP-1) was upregulated in IR cells by the microarray analysis. Here, we investigated the contribution of neuropilin-1 to changes in the characteristics of IR cells. Although there were no differences in angiogenic activity in the tube formation assay between parental and IR cells, the cell motility was increased in IR cells compared to parental cells in the cell migration assay. This enhanced cell motility was suppressed by pretreatment with anti-NRP-1 antibody. Although further studies are necessary to identify other molecules associated with NRP-1, the increase in cellular motility in IR cells might be due to the contribution of NRP-1. Inhibition of NRP-1 would help control tumor malignancy in radiation-surviving NSCLC.

Degree of conversion and dentin bond strength of light-cured multi-mode adhesives pretreated or mixed with sulfinate agents.

The influence of sulfinate agents applied as a dentin pretreatment or a mixture with multi-mode one-step self-etch adhesives (1-SEAs) on the degree of conversion (DC) and micro-tensile bond strength (µTBS) of light-cured 1-SEAs was investigated. 1-SEAs Clearfil Universal Bond Quick (UBQ) or Scotchbond Universal Adhesive (SBU) were applied to dentin in etch&rinse or self-etch mode using various application strategies: 1) no pretreatment, 2) pretreatment with 90 wt% ethanol, 3) pretreatment with a sulfinate agent Clearfil DC Activator (UDC) or Scotchbond Universal DCA (SDC), or 4) a mixture of UBQ+UDC or SBU+SDC. µTBS was measured after 24 h. Additionally, DC was measured using attenuated total reflectance Fourier-transform infrared spectroscopy. Pretreatment with sulfinate agents resulted in the highest µTBS and DC, significantly improving them especially in etch&rinse mode. The mixture of sulfinate agents with 1-SEAs was less effective. Pretreatment with ethanol significantly improved µTBS in etch&rinse mode but compromised µTBS in self-etch mode.

Influence of central and peripheral dentin on micro-tensile bond strength estimated using a competing risk model.

The bonding performance of dental adhesives is most frequently evaluated using the micro-tensile bond strength (µTBS) test. Despite lacking evidence, peripheral specimens are often discarded to avoid regional variability. This study, therefore, examined whether µTBS to central and peripheral dentin differed. Dentin surfaces of extracted human molars were bonded with various self-etch adhesives, built up with a resin composite, cut into beams, and stressed in tension. Failure mode was classified as adhesive, cohesive in dentin, or other using scanning electron microscopy. Since cohesive failures in dentin were frequent and could confound µTBS results, the data from central/peripheral dentin were analyzed using a Weibull competing risk (CR) model distinguishing failure modes, and its outcomes were compared to a conventional failure mode non-distinguishing Weibull model. Based on the strength data of cohesively failed specimens, the CR model also estimated the strength of dentin. For comparison, the ultimate tensile strength (UTS) of dentin was measured in both regions. The conventional model suggested that peripheral µTBS was higher than central µTBS. Conversely, the CR model disclosed no significant difference in µTBS between the regions but indicated a higher strength of peripheral dentin. This finding was confirmed by UTS measurements, and further supported by the significantly higher incidence of cohesive failures in central dentin. Therefore, peripheral specimens can be used in the µTBS test as well as central ones, but a CR model should be used for statistical analysis if cohesive failures in dentin are frequent, as the strength of peripheral dentin is higher.

Efficacy of non-rigid registration technique for misregistration in 3D-CTA fusion imaging.

PURPOSE: To assess whether fusion 3D-CTA images can be corrected using non-rigid registration (NRR) for gastroenterology imaging. METHODS: This study included 55 patients before gastroenterology surgery who underwent preoperative 3D-CTA prior to gastroenterological surgery. We recorded the coordinate of measurement points on the arterial vessels (X, Y, and Z) in each portal phase, original image of the arterial phase, and arterial phase with NRR. The distance of misregistration between the two points was calculated with the coordinate of the original image with NRR and that of the portal phase as true value. RESULTS: The distance of misregistration between the two points in the original arterial and portal phase images was significantly higher than that in the arterial phase image with NRR on all directions (p < 0.01). CONCLUSIONS: This study showed that NRR may correct misregistration on fusion 3D-CTA imaging. Hence, it can visualize correctly the anatomy of the vessel.

Evaluation of computed tomography arterial portography scan timing using different bolus tracking methods.

Computed tomography arterial portography (CTAP) is widely used with a fixed scan timing and contrast medium quantity; however, these parameters are not necessarily optimal. In this study, CTAP scan timing was analyzed by different bolus tracking methods to monitor the inflow of the contrast medium in real-time. A total of 249 patients who underwent CTAP were assessed. In 30 patients, the CTAP scanning began 33 s after contrast medium injection started (fixed method). In 74 patients, the regions of interest (ROIs) were established at two places in the inferior vena cava above the hepatic vein (inferior vena cava-ROI method). In 145 patients, the ROI was established at two places in the liver parenchyma (liver parenchyma-ROI method). Scan timing was considered appropriate when the difference in the CT value between the hepatic and portal veins approached 0; this was observed significantly more with the liver parenchyma-ROI method than with the other methods. CTAP scan timing with the liver parenchyma-ROI method was better than that with the fixed and inferior vena cava-ROI methods.

The combined effect of light-illuminating direction and enamel rod orientation on color adjustment at the enamel borders of composite restorations.

OBJECTIVES: To investigate the effect of light-illuminating direction (from composite or enamel side) on color adjustment at the coronal and cervical enamel borders in composite restorations. MATERIALS AND METHODS: Forty cylindrical holes (3.0-mm diameters) were prepared in bovine enamel disks (1.0-mm thickness). After application of a one-step self-etch adhesive, one of four resin composites (Estelite Asteria, EA; Estelite Pro, EP; Kalore, KA; Clearfil Majesty ES-2 Premium, MJ) was restored in the holes. After 24-h storage, the colors (L*, C*, or h* values) at the restored enamel disks over a black background were measured in a black box using a CIE XYZ camera, spotted with D65 standard illuminant either from coronal or cervical side at 45°/0° geometry. The color shifting rate was calculated at the coronal and cervical enamel borders of the composite restorations, and analyzed by three-way ANOVA with Dunnett's T3 and t test for post hoc analysis (p < 0.05). RESULTS: The light-illuminating directions significantly affected the L* shifting rate at the cervical enamel border in EP and MJ (p < 0.05), and the C* shifting rate at the coronal enamel border in EA, EP, and MJ (p < 0.05). CONCLUSIONS: The color appearance at the border of the composite restoration was influenced by the light-illuminating direction in conjunction with the enamel rod orientation in the coronal or cervical enamel border. CLINICAL RELEVANCE: The line-of-vision angle would affect the perception of color adaptation at the enamel borders in the composite restorations.

[Development of New Digital Phantom Creation Tool for Evaluation of Low-contrast Detectability Using Iterative Reconstruction].

PURPOSE: We developed a novel digital phantom-creation tool that will help formulate the standard shooting method for a three-phase dynamic liver study. Here, we present data demonstrating the usefulness of this tool in the assessment of low-contrast detectability and visibility. METHODS: We performed a visual evaluation by adding a spherical digital phantom with a diameter of 8 mm and a computed tomography (CT) value difference of 10 Hounsfield unit (HU) to images taken using filtered back projection and seven types of adaptive iterative dose reduction 3D (Weak, Mild, eMild, Standard, eStandard, Strong, and eStrong). We also examined the partial-volume effect by drawing a profile curve using a digital phantom with a CT value difference of 30 HU and a diameter of 5 mm. Furthermore, a digital phantom with two kinds of filters (smoothing and Gaussian) was added to the image of the home-made simulated tumor phantom to visual valuate its visibility in the phantom's low-contrast module and the digital phantom. RESULTS: Detection sensitivity was significantly decreased in Standard, eStandard, Strong, and eStrong, and the area under the curve also decreased in a similar fashion. We confirmed that the partial-volume effect was due to the different maximum CT values in the profile curve at 4 and 5 mm thickness. The visibility of the low-contrast module and digital phantom was most consistent when using the Gaussian filter. CONCLUSION: This tool can be used for low-contrast detection ability evaluation.

The strategies used for curing universal adhesives affect the micro-bond strength of resin cement used to lute indirect resin composites to human dentin.

We evaluated the effect of different curing strategies for universal adhesives on micro-tensile bond strength (µTBS) between resin cement and dentin and/or between resin cement and indirect resin composite. Flat coronal dentin surfaces and composite resin disks were pretreated with silane-containing universal adhesives, with or without light-curing on the dentin-side and/or composite resin disk-side. Resin disks were luted onto the pretreated dentin surfaces with the corresponding dual-cure adhesive resin cements and light-cured, and cut into beams after 24-h water storage. After 0 or 10,000 thermocycles (5ºC/55ºC) in a water bath, the µTBS of the composite resin disk-dentin beam was tested. The µTBS was highest when universal adhesives were applied to both the dentin- and the indirect composite resin disk-side, followed by light-curing. Thermocycling decreased µTBS in all but the Scotchbond Universaltreated group, with light-curing on both sides. The effect of curing strategies is dependent upon the materials.

Stress distribution in tooth resin core build-ups with different post-end positions in alveolar bone level under two kinds of load directions.

This study aimed to evaluate influence of different post-end positions in alveolar bone level on stress distributions in resin-core build-up tooth under different load directions. Three-dimensional mathematical models of a root-filled mandibular premolar tooth were constructed. Resin post and core were built-up with six post lengths: 0, 1, 2, 3, 4, and 6 mm. Finite element analysis calculated stress distributions with oblique load of 400 N to buccal cusp 45 degree from buccal side or from lingual side. The 3 mm-post length (post-end position equal to cancellous bone level) caused highest equivalent stress of post-end compared with the shorter or longer post length. When change of load direction, the direction of maximum shear stress became completely opposite at mesiodistal cervical edge of core-part without a change of the magnitude. Changing shear stress direction would increase risk of debonding at mesiodistal cervical edge.

Estrogen alters gonadal soma-derived factor (Gsdf)/Foxl2 expression levels in the testes associated with testis-ova differentiation in adult medaka, Oryzias latipes.

Testis-ova differentiation in sexually mature male medaka (Oryzias latipes) is easily induced by estrogenic chemicals, indicating that spermatogonia persist in sexual bipotentiality, even in mature testes in medaka. By contrast, the effects of estrogen on testicular somatic cells associated with testis-ova differentiation in medaka remain unclear. In this study, we focused on the dynamics of sex-related genes (Gsdf, Dmrt1, and Foxl2) expressed in Sertoli cells in the mature testes of adult medaka during estrogen-induced testis-ova differentiation. When mature male medaka were exposed to estradiol benzoate (EB; 800ng/L), testis-ova first appeared after EB treatment for 14days (observed as the first oocytes of the leptotene-zygotene stage). However, the testis remained structurally unchanged, even after EB treatment for 28days. Although Foxl2 is a female-specific sex gene, EB treatment for 7days induced Foxl2/FOXL2 expression in all Sertoli cell-enclosed spermatogonia before testis-ova first appeared; however, Foxl2 was not detected in somatic cells in control testes. Conversely, Sertoli-cell-specific Gsdf mRNA expression levels significantly decreased after EB treatment for 14days, and no changes were observed in DMRT1 localization following EB treatment, whereas Dmrt1 mRNA levels increased significantly. Furthermore, after EB exposure, FOXl2 and DMRT1 were co-localized in Sertoli cells during testis-ova differentiation, although FOXL2 localization was undetectable in Sertoli-cell-enclosed apoptotic testis-ova, whereas DMRT1 remained localized in Sertoli cells. These results indicated for the first time that based on the expression of female-specific sex genes, feminization of Sertoli cells precedes testis-ova differentiation induced by estrogen in mature testes in medaka; however, complete feminization of Sertoli cells was not induced in this study. Additionally, it is suggested strongly that Foxl2 and Gsdf expression constitute potential molecular markers for evaluating the effects of estrogenic chemicals on testicular somatic cells associated with estrogen-induced testis-ova differentiation in mature male medaka.

The influence of elastic moduli of core materials on shear stress distributions at the adhesive interface in resin built-up teeth.

This study aimed to investigate shear stress distributions in resin built-up teeth using resin composites of varying elastic moduli (E), with or without fiber posts. Three-dimensional mathematical models of a root-filled mandibular premolar tooth were constructed. Resin post and cores were built-up with resin composites of three different E: 12,000, 18,000 and 24,000 MPa, with or without fiber posts. Finite element linear analysis was performed to calculate shear stress distributions at bonding interface between resin core and dentin. Regardless of fiber post insertion, the shear stress on the cervical surface of resin core decreased as the E of resin composites increased. Insertion of fiber posts increased the shear stress on the post surface of resin core, with increases in the E of resin composites. In conclusion, using resin core materials with higher E decreased the shear stress at cervical interface between resin core and dentin regardless of fiber post insertion.

Optimization of the Timing of the Portal Venous Phase in Preoperative 3DCT for Malignant Liver Tumors.

Preoperative three-dimensional computed tomography (3DCT) of the liver is the most important examination in performing preoperative simulation. Detailed visualization of the portal vein using the workstation is critical to enable accurate liver segmentation. However, the timing of imaging in the portal venous phase has mostly been reported equivalent to that of the liver screening examinations commonly performed. The purpose of this study was to examine the optimal timing of image capture to create the best portal vein visualization in preoperative 3DCT of the liver. Seventy-nine patients who underwent hepatectomy for malignant liver tumors were enrolled in this study. All patients were preoperatively examined using protocol A (imaging method separated into a portal venous phase and a hepatic venous phase) and then examined 1 week after surgery using protocol B (normal liver screening protocol). We first established the regions of interest in the portal vein and the hepatic vein and then compared CT values for these regions under protocol A and protocol B. The average CT value of the portal vein in protocol A and B was 239.8±28.1 HU and 202.2±18.5 HU, respectively. The average CT value of the portal vein in protocol A was significantly higher compared with protocol B (p<0.01). By introducing separate timing for portal venous phase imaging before preoperative 3DCT (protocol A), it is possible to satisfactorily depict the portal vein.

Cross-linked dry bonding: A new etch-and-rinse technique.

OBJECTIVE: To determine if acid-etched, cross-linked dentin can be dehydrated without lowering bond strength below that of cross-linked wet-bonded dentin in vitro. METHODS: Using extracted human third molars, control acid-etched dentin was bonded with Single Bond Plus, using either the wet- or dry-bonding technique. Experimental acid-etched dentin was treated with 5mass% grape seed extract (GSE) in different solvents for 1min before undergoing wet vs dry resin-dentin bonding with Single Bond Plus. Completely demineralized dentin beams were treated with 5% GSE for 0, 1 or 10min, before measuring stiffness by 3-point flexure. Other completely demineralized beams were treated similarly and then incubated in buffer for 1 week to measure the collagen solubilization by endogenous dentin proteases. RESULTS: 24h microtensile bond strengths (µTBS) in wet and dry controls were 53.5±3.6 and 9.4±1.8MPa, respectively (p<0.05). 5% GSE in water gave µTBS of 53.7±3.4 and 39.1±9.7MPa (p<0.05), respectively, while 5% GSE in ethanol gave µTBS of 51.2±2.3 and 35.3±2.0MPa (p<0.05). 5% GSE in 5% EtOH/95% water gave wet and dry µTBS of 53.0±2.3 and 55.7±5.1MPa (p>0.05). Cross-linking demineralized dentin with 5% GSE increased stiffness of dentin and decreased collagen degradation (p<0.05). SIGNIFICANCE: 5% GSE pretreatment of acid-etched dentin for 1min permits the dentin to be completely air-dried without lowering bond strength.

Effects of a Dicalcium and Tetracalcium Phosphate-Based Desensitizer on In Vitro Dentin Permeability.

The present study evaluated the effectiveness of a dicalcium and tetracalcium phosphate-based desensitizer in reducing dentin permeability in vitro. Dentin fluid flow was measured before and after treatment of dentin with patent dentinal tubules using 1 or 3 applications of the dicalcium and tetracalcium phosphate containing agent TeethmateTM (TM) and comparing the results with two sodium fluoride varnishes VellaTM (VLA) and VanishTM (VAN), after storage in artificial saliva for 24 h, 48 h and 7 days. Significant differences were observed among the 4 methods employed for reducing dentin permeability (p < 0.001) and the 3 post-treatment times (p < 0.001). VLA and VAN never achieved 50% permeability reductions consistently in any of the 3 time periods. Only the calcium phosphate-based desensitizer applied for 3 times consistently reduced dentin permeability by 50% after 24 h. When applied once, the permeability reduction of TM increased progressively over the 3 time periods. After 7 days, only one and three applications of the calcium phosphate-based desensitizer consistently reduced dentin permeability by more than 50%. Permeability reductions corresponded well with scanning electron microscopy examination of dentinal tubule orifice occlusion in dentin specimens treated with the agents. Overall, the dicalcium and tetracalcium phosphate-based desensitizer is effective in reducing dentin permeability via a tubule occlusion mechanism. The ability of the agent to reduce dentin permeability renders it to be potentially useful as a clinical dentin desensitizing agent, which has to be confirmed in future clinical studies. By contrast, the two sodium fluoride varnishes are not effective in dentin permeability reduction and should be considered as topical fluoride delivering agents rather than tubular orifice-blocking agents.

Is chlorhexidine-methacrylate as effective as chlorhexidine digluconate in preserving resin dentin interfaces?

OBJECTIVES: The aim of the current study was to evaluate the effect of 2% CHX and 2% CHX-methacrylate compared to the resin-dentin bonds created by a two-step etch-and-rinse adhesive system after 24h, 6min and 12min. METHODS: Microtensile bond strengths and interfacial nanoleakage within resin-dentin interfaces created by Adper Single Bond 2, with or without CHX or CHX-methacrylate pre-treatment for 30s on acid-etched dentin surfaces, were evaluated after 24h, 6min and 12min of storage in distilled water at 37°C. RESULTS: Twelve months of storage resulted in a significant decrease in microtensile bond strength in the control group, and significant increases in silver nanoleakage. In contrast, Single Bond 2+CHX, and to a greater extent CHX-methacrylate, significantly reduced the rate of deterioration of resin-dentin interfaces over the 12min water storage period, in terms of bond strength. CONCLUSIONS: Similar to Single Bond 2+CHX, Single Bond+CHX-methacrylates reduced the degradation of resin-bonded interfaces over a 12 month storage period. Thus it can be concluded that Single Bond 2+CHX-methacrylate may be important to improve durability of bonded interfaces and therefore, prolong the life span of adhesive restorations. CLINICAL SIGNIFICANCE: Although CHX primers have been shown to enhance the durability of etch-and-rinse adhesives, that protection is lost after 2h. The use of CHX-methacrylate should last much longer since it may copolymerize with adhesive monomers, unlike CHX.

Application of ethanol improves the resin-dentin bond strength of a two-bottle, self-etching primer-adhesive.

PURPOSE: To investigate whether the application of ethanol to a two-step self-etching adhesive can improve its resin-dentin bond performance. METHODS: Four different ethanol concentrations were added to the adhesive of Clearfil SE Bond to create four ethanol primers (40, 60, 80 or 100% ethanol). 24 extracted third molars were divided into four groups. Each group corresponded to one of the four hydrophobic ethanol primer concentrations. The teeth in the control group were bonded with Clearfil SE Bond according to the manufacturer's instructions. The primed teeth in the experimental groups were treated with the ethanol primer prior to application of the solvent-free adhesive. Microtensile bond strengths (mTBS) were tested 24 hours after specimen preparation. Another 14 teeth were bonded using the same methods to evaluate mTBS after 1 year. Nanoleakage was evaluated under field-emission scanning electron microscopy before and after aging. RESULTS: In the 24-hour group, the mTBS in the 60% ethanol/40% adhesive primer group increased significantly (21.6%, P < 0.05) over the no ethanol control. After 12-month water storage, the bond strength of that experimental group was still higher than that of the control group (19.5%, P < 0.05). Before aging, the nanoleakage was clearly seen in the control group but hardly any was seen in the experimental group. After aging, the nanoleakage increase in the experimental group was much less than that in the control group.

Adhesive sealing of dentin surfaces in vitro: A review.

PURPOSE: This review describes the evolution of the use of dental adhesives to form a tight seal of freshly prepared dentin to protect the pulp from bacterial products, during the time between crown preparation and final cementation of full crowns. The evolution of these "immediate dentin sealants" follows the evolution of dental adhesives, in general. That is, they began with multiple-step, etch-and-rinse adhesives, and then switched to the use of simplified adhesives. METHODS: Literature was reviewed for evidence that bacteria or bacterial products diffusing across dentin can irritate pulpal tissues before and after smear layer removal. Smear layers can be solubilized by plaque organisms within 7-10 days if they are directly exposed to oral fluids. It is likely that smear layers covered by temporary restorations may last more than 1 month. As long as smear layers remain in place, they can partially seal dentin. Thus, many in vitro studies evaluating the sealing ability of adhesive resins use smear layer-covered dentin as a reference condition. Surprisingly, many adhesives do not seal dentin as well as do smear layers. RESULTS: Both in vitro and in vivo studies show that resin- covered dentin allows dentin fluid to cross polymerized resins. The use of simplified single bottle adhesives to seal dentin was a step backwards. Currently, most authorities use either 3-step adhesives such as Scotchbond Multi-Purpose or OptiBond FL or two-step self-etching primer adhesives, such as Clearfil SE, Unifil Bond or AdheSE.

Beta-cyanoalanine synthase as a molecular marker for induced resistance by fungal glycoprotein elicitor and commercial plant activators.

ABSTRACT The biocontrol agent Pythium oligandrum produces glycoprotein elicitor in the cell wall fraction, designated CWP, and induces resistance to a broad range of pathogens. To understand the mechanism of CWP-induced resistance to pathogens, gene expression at the early stage of CWP treatment in tomato roots was analyzed using a cDNA array. At 4 h after CWP treatment, 144 genes were up-regulated and 99 genes were down-regulated. In the 144 up-regulated genes, nine genes exhibited about eightfold increased expression. Analysis of the response of these nine genes to three commercial plant activators indicated that a high level of one gene, beta-cyanoalanine synthase gene (LeCAS) encoding hydrogen cyanide (HCN) detoxification enzyme, was stably induced in tomato roots by such treatment. However, expression of LeCAS was not significantly induced in tomato roots at 4 h by abiotic stresses, whereas only a very low level of induction of such expression by cold stress was observed. This LeCAS expression was also induced after exogenous treatment with a low level of 1-amino-cyclopropane-1-carboxylate as the precursor of ethylene, but not with either salicylic acid or methyl jas-monate. The induction of LeCAS expression in CWP-treated and plant activator-treated roots is likely to be caused by the detoxification of HCN during ethylene production. Transient activation of LeCAS expression caused by ethylene production in tomato roots may be a general phenomenon in fungal elicitor-induced and synthetic plant activator-induced resistance. LeCAS seems to be useful for screening possible novel plant activators for plant protection against pathogens.