A Photograph-Based Visualization and Prediction Framework for Radiation-Induced Dermatitis

PURPOSE/OBJECTIVE(S)

This study aimed to suggest a photograph-based prediction system for acute radiation-induced dermatitis (RID), which can be applied to notify patients about the risk of the development of skin discomfort during radiotherapy.

MATERIALS/METHODS

The proposed system compared the spatial dose distribution with the RID region using the following methods. Skin photographs of patients were taken using an RGB-depth camera to acquire the shape information of RID. The skin surface data measured from the camera was registered with the shape of the external body contour using an iterative closest point algorithm. Spatial dose distribution of skin was extracted from the external body contour to a depth of 2 mm and projected onto the plane of the skin photograph using a transformation matrix for skin depth data. To compare the spatial distribution of skin dose with the shape of RID, the region of RID in patients' skin was delineated on photographs into three toxicity symptoms referring to the CTCAE criteria grade 1 (skin redness), grade 2 (dry desquamation), and grade 3 (moist desquamation). The degree of overlap between the shape of each RID and skin dose distribution was evaluated using the dice similarity coefficient (DSC). Threshold doses for predicting RID occurrence were estimated by skin isodose lines with the highest DSC. The developed system was validated using data from 19 patients who received volumetric modulated arc therapy for head-neck cancer at a single institution.

RESULTS

Threshold doses for RID grades 1, 2, and 3 were estimated using 18, 18, and 2 individual RID labels delineated on skin photographs, respectively. Isodose lines with the highest DSC for RID grades 1, 2, and 3 were calculated as 26.0 Gy, 36.5 Gy, and 54.0 Gy, respectively. A strong overlap (average DSC > 0.6) was observed between isodose skin lines and the shape of RID labels in all RID grades.

CONCLUSION

Assessing the spatial information of skin dose can be helpful in predicting acute RID. The region of RID shows a strong similarity with the skin dose distribution in head-neck patients. Visualization of skin dose on the patient photograph is potent to patient education for preparing the cosmetic discomfort during radiotherapy, which may lead to the improvement of the patient satisfaction in treatment.

A New Approach to Quantify and Grade Radiation Dermatitis Using Deep-Learning Segmentation in Skin Photographs

AIMS

Objective evaluation of radiation dermatitis is important for analysing the correlation between the severity of radiation dermatitis and dose distribution in clinical practice and for reliable reporting in clinical trials. We developed a novel radiation dermatitis segmentation system based on convolutional neural networks (CNNs) to consistently evaluate radiation dermatitis.

MATERIALS AND METHODS

The radiation dermatitis segmentation system is designed to segment the radiation dermatitis occurrence area using skin photographs and skin-dose distribution. A CNN architecture with a dilated convolution layer and skip connection was designed to estimate the radiation dermatitis area. Seventy-three skin photographs obtained from patients undergoing radiotherapy were collected for training and testing. The ground truth of radiation dermatitis segmentation is manually delineated from the skin photograph by an experienced radiation oncologist and medical physicist. We converted the skin photographs to RGB (red-green-blue) and CIELAB (lightness (L^∗), red-green (a^∗) and blue-yellow (b^∗)) colour information and trained the network to segment faint and severe radiation dermatitis using three different input combinations: RGB, RGB + CIELAB (RGBLAB) and RGB + CIELAB + skin-dose distribution (RGBLAB_D). The proposed system was evaluated using the Dice similarity coefficient (DSC), sensitivity, specificity and normalised Matthews correlation coefficient (nMCC). A paired t-test was used to compare the results of different segmentation performances.

RESULTS

Optimal data composition was observed in the network trained for radiation dermatitis segmentation using skin photographs and skin-dose distribution. The average DSC, sensitivity, specificity and nMCC values of RGBLAB_D were 0.62, 0.61, 0.91 and 0.77, respectively, in faint radiation dermatitis, and 0.69, 0.78, 0.96 and 0.83, respectively, in severe radiation dermatitis.

CONCLUSION

Our study showed that CNN-based radiation dermatitis segmentation in skin photographs of patients undergoing radiotherapy can describe radiation dermatitis severity and pattern. Our study could aid in objectifying the radiation dermatitis grading and analysing the reliable correlation between dosimetric factors and the morphology of radiation dermatitis.

Improved Electroluminescence Performance of Perovskite Light-Emitting Diodes by a New Hole Transporting Polymer Based on the Benzocarbazole Moiety

A new hole-transporting material, poly-2-(9H-carbazol-9-yl)-5-(4-vinylphenyl)-5H-benzo[b]carbazole (PBCZCZ), was developed for perovskite light-emitting diodes (PeLEDs). This polymer, which is based on the benzocarbazole moiety, has good solubility in common solvents and enabled the fabrication of highly efficient multilayer perovskite devices. It has excellent film morphology and a high hole mobility of 3.67 × 10^-5 cm² V^-1 s^-1, which made it possible to vary the device configuration. Green and sky-blue perovskite PeLEDs using PBCZCZ as the hole-transporting layer had current efficiencies and external quantum efficiencies (EQEs) of 43.90 cd A^-1 and 8.67% for the green device and 9.07 cd A^-1 and 4.04% for the sky-blue device, respectively. The EQE of the green PeLEDs was about 2.5 times higher and that of the sky-blue PeLEDs was about 3 times higher than the device made with the commercial HTL of poly(9-vinylcarbazole) (PVK). The operational device lifetimes of the green and sky-blue PeLEDs made with PBCZCZ were about 4.1 and 4.8 times higher than the PVK-containing device, respectively.

Guideline on safety evaluation of cell-based medicinal products for animal use

With the increased use of cell therapy in the veterinary sector, there is a growing demand for the development of cell-based medicinal products and the determination of their safety. Currently, the Korean Animal and Plant Quarantine Agency has established a guideline for evaluating the safety of cell-based medicinal products for animal use. The guideline includes items related to definition, classification, management, manufacturing procedure and quality control (standard and test method), stability testing, toxicity testing, pharmacological testing, and performance of clinical trials. In addition, testing protocols related to safety assessment of animal cell-based products such as chromosome karyotyping, tumorigenicity testing, confirmatory testing of biodistribution and kinetics, and target animal safety testing are described in detail. Moreover, because cell-based medicinal products are novel therapies, deviations from traditional designs may be justified in order to obtain relevant safety information on the treatment. Additionally, this guideline can be amended on the basis of new scientific findings.

High-content analysis of in vitro hepatocyte injury induced by various hepatotoxicants

In vitro prediction of hepatotoxicity can enhance the performance of non-clinical animal testing for identifying chemical hazards. In this study, we assessed high-content analysis (HCA) using multi-parameter cell-based assays as an in vitro hepatotoxicity testing model using various hepatotoxicants and human hepatocytes such as HepG2 cells and human primary hepatocytes (hPHs). Both hepatocyte types were exposed separately to multiple doses of ten hepatotoxicants associated with liver injury whose mechanisms of action have been described. HCA data were obtained using fluorescence probes for nuclear size (Hoechst), mitochondrial membrane potential (TMRM), cytosolic free calcium (Fluo-4AM), and lipid peroxidation (BODIPY). Cellular alterations were observed in response to all hepatotoxicants tested. The most sensitive parameter was TMRM, with high sensitivity at a low dose, next was BODIPY, followed by Fluo-4AM. HCA data from HepG2 cells and hPHs were generally concordant, although some inconsistencies were noted. Both hepatocyte types showed mild or severe mitochondrial impairment and lipid peroxidation in response to several hepatotoxicants. The results demonstrate that the application of HCA to in vitro hepatotoxicity testing enables more efficient hazard identification, and further, they suggest that certain parameters could serve as sensitive endpoints for predicting the hepatotoxic potential of chemical compounds.

Comparison of microRNA expressions for the identification of chemical hazards in in vivo and in vitro hepatic injury models

Biofluid-based biomarkers provide an efficient tool for hazard identification of chemicals. Here, we explored the potential of microRNAs (miRNAs) as biomarkers for hepatotoxicity of chemicals by linking in vitro to in vivo animal models. A search of the literature identified candidate circulating miRNA biomarkers of chemical-induced hepatotoxicity. The expression of candidate miRNAs (miR-122, miR-151a, miR-192, miR-193a, miR-194, miR-21, miR-29c), was determined by real-time reverse transcription-polymerase chain reaction in in vivo acute liver injury induced by acetaminophen, and then were further compared with those of in vitro cell assays. Candidate miRNAs, except miR-29c, were significantly or biologically upregulated by acetaminophen, at a dose that caused acute liver injury as confirmed by hepatocellular necrosis. Except miR-122 and miR-193a, other miRNAs elevated in in vivo models were confirmed by in vitro models using HepG2 cells, whereas they failed by in vitro models using human primary hepatocytes. These findings indicate that certain miRNAs may still have the potential of toxicological biomarkers in linking in vitro to in vivo hepatotoxicity.

Hepatic population derived from human pluripotent stem cells is effectively increased by selective removal of undifferentiated stem cells using YM155

Background

Pluripotent stem cells (PSCs) such as embryonic stem cells and induced pluripotent stem cells are promising target cells for cell regenerative medicine together with recently advanced technology of in-vitro differentiation. However, residual undifferentiated stem cells (USCs) during in-vitro differentiation are considered a potential risk for development of cancer cells and nonspecific lineage cell types. In this study we observed that USCs still exist during hepatic differentiation, consequently resulting in poor quality of the hepatic population and forming teratoma in vivo. Therefore, we hypothesized that effectively removing USCs from in-vitro differentiation could improve the quality of the hepatic population and guarantee safety from risk of teratoma formation.

Methods

Human PSCs were differentiated to hepatocytes via four steps. YM155, a known BIRC5 inhibitor, was applied for removing the residual USCs on the hepatic differentiation. After YM155 treatment, hepatocyte development was evaluated by measuring gene expression, immunostaining and hepatic functions at each stage of differentiation, and forming teratomas were confirmed by cell transplantation with or without YM155.

Results

The selected concentrations of YM155 removed USCs (NANOG⁺ and OCT4⁺) in a dose-dependent manner. As a result, expression of endodermal markers (SOX17, FOXA2 and CXCR4) at stage II of differentiation and hepatic markers (ALB, AFP and HNF4A) at stage III was up-regulated by YM155 treatment as well as the hepatic population (ALB⁺), and functions (ALB/urea secretion and CYP450 enzyme activity) were enhanced at the final stage of differentiation (stage IV). Furthermore, we demonstrated that NANOG and OCT4 expression remaining until stage III (day 15 of differentiation) completely disappeared when treated with YM155 and teratoma formation was effectively prevented by YM155 pretreatment in the in-vitro study.

Conclusions

We suggest that the removal of USCs using YM155 could improve the quantity and quality of induced hepatocytes and eliminate the potential risk of teratoma formation.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0517-2) contains supplementary material, which is available to authorized users.

Magnetic nanoparticle based purification and enzyme-linked immunosorbent assay using monoclonal antibody against enrofloxacin

Monoclonal anti-enrofloxacin antibody was prepared for a direct competitive enzyme-linked immunosorbent assay (ELISA) and purification system using monoclonal antibody (mAb) coupled magnetic nanoparticles (MNPs). The IC₅₀ values of the developed mAb for enrofloxacin (ENR), ciprofloxacin, difloxacin, sarafloxacin, pefloxacin, and norfloxacin were 5.0, 8.3, 9.7, 21.7, 36.0, and 63.7 ng/mL, respectively. The lowest detectable level of ENR was 0.7 ng/mL in the prepared ELISA system. To validate the developed ELISA in the food matrix, known amounts of ENR were spiked in meat and egg samples at 10, 20 and 30 ng/mL. Recoveries for ENR ranged from 72.9 to 113.16% with a coefficient of variation (CV) of 2.42 to 10.11%. The applicability of the mAb-MNP system was verified by testing the recoveries for ENR residue in three different matrices. Recoveries for ENR ranged from 75.16 to 86.36%, while the CV ranged from 5.08 to 11.53%. Overall, ENR-specific monoclonal antibody was prepared and developed for use in competitive to ELISAs for the detection of ENR in animal meat samples. Furthermore, we suggest that a purification system for ENR using mAb-coupled MNPs could be useful for determination of ENR residue in food.

Stimuli-Responsive Genetically Engineered Polymer Hydrogel Demonstrates Emergent Optical Responses

Biopolymer-based optical hydrogels represent an emerging class of materials with potential applications in biocompatible integrated optoelectronic devices, bioimaging applications, and stretchable/flexible photonics. We have synthesized stimuli-responsive three-dimensional hydrogels from genetically engineered elastin-like polymers (ELPs) and have loaded these hydrogels with an amine-containing p-phenylenevinylene oligomer (OPPV) derivative featuring highly tunable, environmentally sensitive optical properties. The composite ELP/OPPV hydrogels exhibit both pH- and temperature-dependent fluorescence emission, from which we have characterized a unique optical behavior that emerged from OPPV within the hydrogel environment. By systematic comparison with free OPPV in solution, our results suggest that this distinct behavior is due to local electronic effects arising from interactions between the hydrophobic ELP microenvironment and the nonprotonated OPPV species at pH 7 or higher.

Chemically induced hepatotoxicity in human stem cell-induced hepatocytes compared with primary hepatocytes and HepG2

Stem cell-induced hepatocytes (SC-iHeps) have been suggested as a valuable model for evaluating drug toxicology. Here, human-induced pluripotent stem cells (QIA7) and embryonic stem cells (WA01) were differentiated into hepatocytes, and the hepatotoxic effects of acetaminophen (AAP) and aflatoxin B1 (AFB1) were compared with primary hepatocytes (p-Heps) and HepG2. In a cytotoxicity assay, the IC50 of SC-iHeps was similar to that in p-Heps and HepG2 in the AAP groups but different from that in p-Heps of the AFB1 groups. In a multi-parameter assay, phenotypic changes in mitochondrial membrane potential, calcium influx and oxidative stress were similar between QIA7-iHeps and p-Heps following AAP and AFB1 treatment but relatively low in WA01-iHeps and HepG2. Most hepatic functional markers (hepatocyte-specific genes, albumin/urea secretion, and the CYP450 enzyme activity) were decreased in a dose-dependent manner following AAP and AFB1 treatment in SC-iHeps and p-Heps but not in HepG2. Regarding CYP450 inhibition, the cell viability of SC-iHeps and p-Heps was increased by ketoconazole, a CYP3A4 inhibitor. Collectively, SC-iHeps and p-Heps showed similar cytotoxicity and hepatocyte functional effects for AAP and AFB1 compared with HepG2. Therefore, SC-iHeps have phenotypic characteristics and sensitivity to cytotoxic chemicals that are more similar to p-Heps than to HepG2 cells.

Macaca specific exon creation event generates a novel ZKSCAN5 transcript

ZKSCAN5 (also known as ZFP95) is a zinc-finger protein belonging to the Krűppel family. ZKSCAN5 contains a SCAN box and a KRAB A domain and is proposed to play a distinct role during spermatogenesis. In humans, alternatively spliced ZKSCAN5 transcripts with different 5'-untranslated regions (UTRs) have been identified. However, investigation of our Macaca UniGene Database revealed novel alternative ZKSCAN5 transcripts that arose due to an exon creation event. Therefore, in this study, we identified the full-length sequences of ZKSCAN5 and its alternative transcripts in Macaca spp. Additionally, we investigated different nonhuman primate sequences to elucidate the molecular mechanism underlying the exon creation event. We analyzed the evolutionary features of the ZKSCAN5 transcripts by reverse transcription polymerase chain reaction (RT-PCR) and genomic PCR, and by sequencing various nonhuman primate DNA and RNA samples. The exon-created transcript was only detected in the Macaca lineage (crab-eating monkey and rhesus monkey). Full-length sequence analysis by rapid amplification of cDNA ends (RACE) identified ten full-length transcripts and four functional isoforms of ZKSCAN5. Protein sequence analyses revealed the presence of two groups of isoforms that arose because of differences in start-codon usage. Together, our results demonstrate that there has been specific selection for a discrete set of ZKSCAN5 variants in the Macaca lineage. Furthermore, study of this locus (and perhaps others) in Macaca spp. might facilitate our understanding of the evolutionary pressures that have shaped the mechanism of exon creation in primates.

Effect on the H19 gene methylation of sperm and organs of offspring after chlorpyrifos-methyl exposure during organogenesis period

To elucidate the effect on the H19 gene methylation of sperm and organs in offspring by chlorpyrifos-methyl (CPM) exposure during organogenesis period, CPM was administered at doses of 4 (CPM4), 20 (CPM20), and 100 (CPM100) mg/kg bw/day from 7 days post coitum (d.p.c.) to 17 d.p.c. after mating CAST/Ei (♂) and B6 (♀). Anogenital distance (AGD) was measured at postnatal day (PND) 21. Clinical signs, body weights, feed and water consumption, organs weights, serum hormone values, and H19 methylation level of organ and sperm were measured at PND63. Body weights were significantly lower than control until PND6. AGD was significantly decreased in the CPM100 group in males and increased in the CPM20 group in females. The absolute weights of the thymus and epididymis were significantly increased for males in all of CPM treatment groups. In the CPM20 group, absolute weights of liver, kidney, heart, lung, spleen, prostate gland, and testes were significantly increased. Testosterone concentrations in serum were significantly increased by CPM treatment in males. H19 methylation level of liver and thymus showed decreased pattern in a dose-dependent manner in males. The levels of H19 methylation in sperm were 73.76 ± 7.16% (Control), 57.84 ± 12.94% (CPM4), 64.24 ± 3.79% (CPM20), and 64.24 ± 3.79% (CPM100). Conclusively, CPM exposure during organogenesis period can disrupt H19 methylation in sperm, liver, and thymus and disturb the early development of offspring.

Comparison of two different S-1 plus cisplatin dosing schedules as first-line chemotherapy for metastatic and/or recurrent gastric cancer: a multicenter, randomized phase III trial (SOS)

BACKGROUND

Five-weekly S-1 plus cisplatin (SP5) is one of the standard first-line regimens for advanced gastric cancer (GC), proven in a Japanese phase III study. To enhance the dose intensity of cisplatin, 3-weekly S-1 plus cisplatin (SP3) was developed.

PATIENTS AND METHODS

This multicenter, randomized, open-label, phase III study evaluated whether SP3 (S-1 80 mg/m(2)/day on days 1-14 and cisplatin 60 mg/m(2) on day 1) was noninferior/superior to SP5 (S-1 80-120 mg/day on days 1-21 and cisplatin 60 mg/m(2) on day 1 or 8) in terms of progression-free survival (PFS). Chemotherapy-naive patients with metastatic, recurrent gastric or gastroesophageal junction adenocarcinoma were randomized 1 : 1 to receive either SP3 or SP5. The trial is registered at ClinicalTrials.gov (NCT00915382).

RESULTS

Between February 2009 and January 2012, 625 patients were randomized at 42 sites in Korea and Japan. With a median follow-up duration of 32.4 months (range, 13.3-48.6 months) in surviving patients, SP3 was not only noninferior but also superior to SP5 in terms of PFS [median 5.5 versus 4.9 months; hazard ratio (HR) = 0.82; 95% confidence interval (CI) 0.68-0.99; P = 0.0418 for superiority). There was no difference in overall survival (OS) between the groups (median 14.1 versus 13.9 months; HR = 0.99; 95% CI 0.81-1.21; P = 0.9068). In patients with measurable disease, the response rates were 60% in the SP3 arm and 50% in the SP5 arm (P = 0.065). Both regimens were generally well tolerated, but grade 3 or higher anemia (19% versus 9%) and neutropenia (39% versus 9%) were more frequent in SP3.

CONCLUSIONS

SP3 is superior to SP5 in terms of PFS. However, since the improvement in PFS was only slight and there was no difference in OS, both SP3 and SP5 can be recommended as first-line treatments for patients with advanced GC.

A new pH sensitive fluorescent and white light emissive material through controlled intermolecular charge transfer

A new, pH dependent and water-soluble, conjugated oligomer (amino, trimethylammonium oligophenylene vinylene, ATAOPV) was synthesized with a quaternary ammonium salt and an aromatic amine at the two ends of a π-conjugated oligomer, thus creating a strong dipole across the molecule. A unique white light LED is successfully fabricated from a stimuli responsive organic molecule whose emission properties are dominated by the pH value of the solution through controlled intermolecular charge transfer.

Sodium butyrate efficiently converts fully reprogrammed induced pluripotent stem cells from mouse partially reprogrammed cells

Partially reprogrammed cells [preinduced pluripotent stem cells (pre-iPSCs)] commonly stall at epigenetic barriers, and this is one of the major failures in the reprogramming process. These cells can be converted to the fully reprogrammed state by reducing epigenetic blocks. In this study, we established three iPSC lines and two pre-iPSC lines induced by the doxycycline (dox)-inducible lentiviral system. In the pre-iPSC lines maintained under dox treatment (dox(+)), a small portion of embryonic stem cell (ESC)-like colonies spontaneously emerged after dox withdrawal (dox(-)), and major differentiation into fibroblast-like cells occurred. The spontaneous conversions based on the number of stage-specific embryonic antigen-1-positive (SSEA-1(+)) colonies were 0.006 ± 0.004% [mean ± standard deviation (SD)] for the #89-7D line and 0.016 ± 0.004% for the #102-2D line. The SSEA-1(+) colonies did not express the Nanog protein. However, the colonies showed characteristics typical of fully reprogrammed iPSCs after further expansion. To determine whether spontaneous conversion could be improved by epigenetic modification, we applied four small molecules-valproic acid (VPA), sodium butyrate (SB), trichostatin (TSA), and 5-aza-2'-deoxycytidine (5-Aza)-in both pre-iPSC lines. SB was the most effective molecule in enhancing the number of SSEA-1(+) colonies (32- to 39-fold) at day 5 of dox(-) treatment. In addition, the expression of pluripotent genes (sox2 and nanog) was increased by SB. After exposure to SB, we found that the expression of four reprogramming factors and cell cycle-related genes was relatively increased compared to their expression following dox(+) of pre-iPSCs. These changes caused by SB might play an important role in the spontaneous conversion of partially reprogrammed cells.

Toxic effects of methylmercury, arsanilic acid and danofloxacin on the differentiation of mouse embryonic stem cells into neural cells

This study was performed to assess the neurotoxic effects of methylmercury, arsanilic acid and danofloxacin by quantification of neural-specific proteins in vitro. Quantitation of the protein markers during 14 days of differentiation indicated that the mouse ESCs were completely differentiated into neural cells by Day 8. The cells were treated with non-cytotoxic concentrations of three chemicals during differentiation. Low levels of exposure to methylmercury decreased the expression of GABAA-R and Nestin during the differentiating stage, and Nestin during the differentiated stage. In contrast, GFAP, Tuj1, and MAP2 expression was affected only by relatively high doses during both stages. Arsanilic acid affected the levels of GABAA-R and GFAP during the differentiated stage while the changes of Nestin and Tuj1 were greater during the differentiating stage. For the neural markers (except Nestin) expressed during both stages, danofloxacin affected protein levels at lower concentrations in the differentiated stage than the differentiating stage. Acetylcholinesterase activity was inhibited by relatively low concentrations of methylmercury and arsanilic acid during the differentiating stage while this activity was inhibited only by more than 40 μM of danofloxacin in the differentiated stage. Our results provide useful information about the different toxicities of chemicals and the impact on neural development.

Expression of epithelial cell adhesion molecule and proliferating cell nuclear antigen in diethylnitrosamine-induced hepatocarcinogenesis in mice

To clarify the role of stem cells in hepatocarcinogenesis, the expression of epithelial cell adhesion molecule (EpCAM) and proliferating cell nuclear antigen (PCNA) was investigated in mouse hepatic tumors and embryonic cell lineages. Ten ICR mice were treated with diethylnitrosamine (DEN) at 14 days of age and sacrificed at 36 weeks subsequent to DEN treatment to obtain the hepatic tumors. Mouse embryonic stem cells, hepatic progenitor cells and hepatocyte-like cells, representing 0, 22 and 40 days of differentiation, respectively, were treated in vitro with DEN at four doses (0, 1, 5 and 15 mM; G1, G2, G3 and G4, respectively) for 24 h and RNA was isolated. A total of 71 hepatic tumors were obtained from the DEN-treated mice. EpCAM expression was increased mainly in hepatic tumor cells, although it was also detected in the surrounding visually normal cells. Double staining showed that EpCAM and PCNA were co-expressed in numerous tumor cells. In vitro, EpCAM expression was significantly different for G4 at day 0 (P<0.01) and for G2, G3 and G4 at day 40 (P<0.01) compared with the control (G1) at the corresponding time-point. PCNA expression was significantly different for G3 and G4 at day 0 (P<0.01), for G2, G3 and G4 at day 22 (P<0.01) and for G2 at day 40 (P<0.01) compared with G1 at the corresponding time-point. In summary, the expression of EpCAM and PCNA was increased in DEN-induced tumors and the expression of EpCAM and PCNA was altered by DEN treatment in cultured cells. This suggests that EpCAM expression may be modulated in the progeny of adult liver stem cells during their differentiation toward hepatocytes and may be increased during DEN-induced hepatocarcinogenesis.

Effect of chemotherapy on the outcome of self-expandable metallic stents in gastric cancer patients with malignant outlet obstruction

BACKGROUND AND STUDY AIM

Chemotherapy has been suggested to affect the outcome of pyloric stent placement. This study aimed to investigate the association between the response to chemotherapy and pyloric stent outcome.

PATIENTS AND METHODS

Data from 113 patients with inoperable gastric cancer who received chemotherapy after pyloric stent placement at the National Cancer Center hospital were analyzed retrospectively. Chemotherapy response was assessed using the Response Evaluation Criteria in Solid Tumors. A Cox proportional hazards model was used to evaluate the effect of chemotherapy response on the complications of stents.

RESULTS

The stent migration rate was 15.9% (18/113) and the re-stenosis rate was 30.1% (34/113). The response rates to chemotherapy were higher in the first-line group than in the salvage chemotherapy group (second-line or more) (44.8% [26/58] vs. 3.6% [2/55], respectively; P < 0.001). The proportion of patients with long time-to-progression (> 8 weeks) was also higher in the first-line than the salvage chemotherapy group (81.0% [47 /58] vs. 61.8% [34 /55], respectively; P = 0.036). Although, the response to chemotherapy was not associated with stent migration or re-stenosis, a long time-to-progression (adjusted hazard ratio [aHR] = 0.29, 95% confidence interval [CI] 0.13-0.67) and first-line chemotherapy (aHR = 0.45, 95%CI 0.22-0.93) were protective factors against re-stenosis in the multivariate analysis. In patients who received first-line chemotherapy, the median duration of patency of covered and uncovered stents was 20 weeks (95%CI 11-29) and 33 weeks (95 %CI 18-48), respectively (P = 0.317).

CONCLUSIONS

A long time-to-progression and first-line chemotherapy were significant protective factors against re-stenosis. In chemotherapy-naïve gastric cancer patients with pyloric obstruction, placement of an uncovered stent followed by chemotherapy can be considered to increase stent patency.

Structural and functional studies of casein kinase I-like protein from rice

Casein kinase I (CKI) is a protein serine/threonine kinase that is highly conserved from plants to animals. It performs various functions in both the cytoplasm and nucleus, such as DNA repair, cell cycle, cytokinesis, vesicular trafficking, morphogenesis and circadian rhythm. CKI proteins contain a highly conserved kinase domain responsible for catalytic activity at the N-terminus and a highly diverse regulatory domain responsible for determining substrate specificity at the C-terminus. CKI-like protein has been identified in plants, including in rice, but its function and structure have not been reported. Here, we report the 2.0 Å crystal structure of the kinase domain of CKI-like protein from rice. Although the structure adopts the typical bi-lobal kinase architecture, the length and orientation of the glycine-rich ATP-binding motif are dynamic within the CKI family. A loop between α5 and α6 (the α5-α6 loop), which was previously not detected in the CKI family because of flexibility, was clearly detected in our structure. In addition, we identified a lipase as a substrate of CKI-like protein from rice. Phosphorylation of the lipase dramatically reduced its catalytic activity, suggesting that CKI may play a role in the regulation of lipase activity.

New deep blue emitting materials based on indenopyrazine core with high thermal stability

New deep blue emitting materials 2,8-bis(3,5-diphenylphenyl)-6,6,12,12-tetraethyl-6,12-dihydrodiindeno[1,2-b:1',2'-e]pyrazine (DPP-EPY) and 2,8-bis(3',5'-diphenylbiphenyl-4-yl)-6,6,12,12-tetraethyl-6,12-dihydrodiindeno[1,2-b:1',2'-e]pyrazine (DPBP-EPY) were synthesized through introduction of m-terphenyl or triphenylbenzene bulky side groups in a new indenopyrazine core. These materials all showed high thermal stability and highly reduced intermolecular interaction. DPP-EPY and DPBP-EPY showed PL maxima of 456 nm and 460 nm in deep blue region and narrow PL spectra with full-width at half-maximum (FWHM) of 46 nm and 52 nm, respectively. As a result of making non-doped OLED devices using these synthesized materials as emitting layers, DPP-EPY showed EL spectrum of 452 nm, very narrow FWHM of 46 nm, luminance efficiency of 1.04 cd/A with current density of 10 mA/cm2 and CIE coordinate of (0.161, 0.104), creating a deep blue OLED close to the National Television System Committee (NTSC) blue standard.

Electronic structure study on the electroluminescent properties of fully substituted ethylene derivatives

The correlation between the molecular conformations and the electroluminescent properties of fully substituted ethylene derivatives has been studied with semiempirical molecular orbital calculations. It was found that the existence of intramolecular interactions between anthracenes in (Z)-form isomers lower their energies. UV-visible spectra were also predicted by configuration interaction calculations, and compared with experimental results.

Comparison of the diagnostic methods on the canine adenovirus type 2 infection

Background and aims: Canine adenovirus type 2 (CAV‐2) infection is typically diagnosed histopathologically since intranuclear inclusion bodies (IN/IBs) are demonstrable in the infected lung. However, it is sometimes difficult to identify IN/IBs, particularly in autolyzed tissues or samples from both early and late stages of infection, and other methods were presently developed. Methods: Stray dog samples were evaluated by histopathology, polymerase chain reaction (PCR), and immunohistochemistry (IHC) to investigate the status of the CAV‐2 infection on the stray dogs in Korea. Histologic tests were performed, and dogs with pneumonic lungs were further evaluated by IHC and PCR. Results: Pathognomonic IN/IBs were identified in 3 of 213 lungs; CAV‐2 PCR was positive for 27 of 213 pneumonic lungs. A total of 7 of 27 CAV‐2 PCR‐positive lungs were IHC‐positive. No PCR‐negative lung was IHC‐positive. Positive results were primarily detected in the IN/IBs of the bronchial epithelial cells, macrophages, and very rarely in the cytoplasm of bronchial epithelial cells. Conclusions: IHC was a more reliable diagnostic method than conventional pathologic methods in the present study, and suggests that IHC should be routinely used in the diagnosis of CAV‐2 infection. Further, PCR alone may not be adequate for CAV‐2 diagnosis.

Core-structure effects of novel indenopyrazine derivatives for blue emitter

A novel core material, indenopyrazine, has been substituted with ethyl, phenyl, tolyl or fluorenyl groups on the locations 6 and 12, to newly synthesize four blue-emitting materials for OLED. Their electro-optical properties were compared through UV-Vis absorption, PL spectra and cyclic voltammetry, according to substituents of the core system of indenopyrazine. Non-doped OLED devices were fabricated by using the synthesized materials as emitting material layers, and among them, SF-EPY showed a highly-efficient luminescence with EL spectrum of 458 nm, luminous efficiency of 2.62 cd/A and CIE coordinates of (0.152, 0.142) at a current density of 10 mA/cm2.

Adult cor triatriatum presenting as cardioembolic stroke

Cor triatriatum is a rare congenital cardiac malformation characterized by a fibromuscular membrane that divides the left atrium into two distinct chambers. In almost all cases, it is diagnosed in childhood, whereas adult cases are extremely rare. Herein, we describe an unusual case of cor triatriatum in a 55-year-old woman who presented with embolic cerebral infarction. The patient experienced sudden-onset, transient left-sided homonymous hemianopsia and echocardiography and multidetector computed tomography detected a membrane-like structure across the left atrium, confirming the diagnosis of a cor triatriatum. The laboratory examination for hypercoagulopathy was negative. She was conservatively treated with anticoagulation and her neurological manifestation gradually improved.

New hole transporting materials based on di- and tetra-substituted biphenyl derivatives for organic light-emitting diodes

This study aimed to synthesize novel hole transporting materials (HTMs) with biphenyl derivatives that are di- or tetra-substituted with naphthylphenyl amine groups and/or methoxy groups, and to examine systematically the variations of the properties of the HTMs with the number and location of the substituents. The tetranaphthylphenyl amine-substituted biphenyl-based HTMs T1N and T2N were observed to have better thermal properties than the commercial HTM NPB, with decomposition temperatures above 500 degrees C, and a 10 degrees C higher T(g). In EL devices with ITO/2-TNATA-(60 nm)/HTM(15 nm)/Alq3(70 nm)/LiF(1 nm)/Al structures, the disubstituted biphenyl-based HTMs with an asymmetric molecular structure D1N and D2N were found to have inferior luminescence efficiencies when compared to NPB, which has a symmetric molecular structure. However, M1N, which is substituted with a further two methoxy groups, was found to exhibit excellent luminance and power efficiencies, 4.88 cd/A and 1.36 Im/W respectively at 100 mA/cm2, which are higher by about 147% and 127% respectively than those of NPB (3.30 cd/A and 1.07 Im/W at 100 mA/cm2), due to better charge balance.

Effects of N-terminal modification of recombinant human cytochrome P450 1A2 on catalytic activity

1. The high-level expression of mammalian cytochrome P450 in bacteria usually requires modification of the amino-terminal region of the enzyme. The effect of altering amino acids in the N-terminus of human recombinant CYP1A2 on its catalytic activity was investigated herein. 2. Rates of 7-ethoxyresorufin O-deethylation by CYP1A2a (a form made by altering the amino acids LLL of CYP1A2 to RER at positions 3-5) in reconstituted systems were significantly low compared with those of other CYP1A2 N-terminal variants at a low ratio of cytochrome P450 to NADPH-cytochrome P450 reductase, but not at higher reductase concentrations. 3. CYP1A2a-dependent ethoxyresorufin O-deethylase activity in a cumene hydroperoxide-supported system was approximately 2-fold higher than other CYP1A2 N-terminal variants. 4. Our results suggest that modification of three N-terminal amino acids in CYP1A2 alters the interaction between CYP1A2 and the reductase in reconstituted phospholipid vesicles and in the bicistronic membranes.

Effect of mycelial extract of Clavicorona pyxidata on the production of amyloid beta-peptide and the inhibition of endogenous beta-secretase activity in vitro

Amyloid beta-peptide (Abeta), which is a product of the proteolytic effect of beta-secretase (BACE) on an amyloid precursor protein, is closely associated with Alzheimer's disease (AD) pathogenesis. There is sufficient evidence to suggest that a BACE inhibitor may reduce Abeta levels, thus decreasing the risk of AD. In a previous study, an extract of Clavicorona pyxidata DGUM 29005 mycelia was found to inhibit the production of a soluble beta-amyloid precursor protein (sbetaAPP), Abeta, and BACE in neuronal cell lines. We sought to determine whether this mycelial extract exerts the same effect in human rhabdomyosarcoma A-204 and rat pheochromocytoma PC-12 cells. We found that the production of Abeta decreased in a dose-dependent manner in the presence of the mycelial extract and that the concentration of Abeta never exceeded 50 microg/ml. The presence of sAPP was detected in every culture medium to which the mycelial extract had been added and its concentration remained the same, regardless of the concentration of the extract used. Endogenous beta-secretase activity in A-204 and PC-12 cellular homogenates also decreased in the presence of this extract. These cells, in culture, were not susceptible to the cytotoxic activity of the mycelial extract.

Effect of mycelial extract of Clavicorona pyxidata on acetylcholinesterase and beta-secretase activity in vitro

In a previous study, an extract of Clavicorona pyxidata DGUM 29005 mycelia demonstrated an inhibitory effect against enzyme-associated perceptual disorders. We have attempted to determine whether this mycelial extract is also capable of inhibiting the activities of acetylcholinesterase (AChE) and beta-secretase (BACE) activity. Butanol, ethanol, and water extracts of C. pyxidata DGUM 29005 mycelia were shown to inhibit AChE activity by 99.3%, 93.7%, and 91.7%, respectively. The inhibitory value of the butanol extract was more profound than that of tacrine (95.4%). The ethanol extract also exerted an inhibitory effect against BACE activity; this fraction may harbor the potential for development into a pharmocotherapeutic modality for the treatment of Alzheimer's disease (AD) patients. Rat pheochromocytoma PC12 cells in culture were not determined to be susceptible to the cytotoxic activity evidenced by the mycelial extract. The ethanol extract inhibited endogenous AChE activity in PC12 cellular homogenates, with an IC50 of 67.5 microg/ml, after incubation with intact cells, and also inhibited BACE activity in a dose-dependent fashion. These results suggest that the C. pyxidata mycelial extract has the potential to enhance cholinergic function and, therefore, may perform a function in the amelioration of the cholinergic deficit observed in cases of AD, as well as other types of age-associated memory impairment.

Dicistronic expression of the green fluorescent protein and antibiotic resistance genes in the plastid for selection and tracking of plastid-transformed cells in tobacco

A plastid transformation vector was constructed for dicistronic expression of the aminoglycoside 3'-adenyltransferase (aadA) and green fluorescent protein (gfp) genes under the control of the plastid rrn promoter. Gold particles coated with the vector DNA were bombarded onto tobacco leaf explants using a particle delivery system. Leaf explants produced adventitious shoots when cultured on shoot-inducing medium containing 500 mg l(-1) spectinomycin. Shoots that exhibited green fluorescence under UV light were selected. Southern blot analysis detected the presence of the aadA and gfp genes between trnA and trnI in the plastid genome. Northern blot analysis revealed that the aadA and gfp genes were both properly transcribed into a dicistronic transcriptional unit. The expression of the gfp gene in the plastid enabled separation of transformed chloroplasts from wild-type chloroplasts in the protoplast under a fluorescent microscope. The overall results indicate that dicistronic expression of the aadA and gfp genes in the plastid simplifies gene manipulation, facilitating selection and tracking of plastid-transformed cells.

Protein 4.1 deficiency and deletion of chromosome 20q are associated with acquired elliptocytosis in myelodysplastic syndrome

We report a case of myelodysplastic syndrome (MDS), associated with prominent elliptocytosis. A 66-year-old male presented with peripheral pancytopenia, and was diagnosed with MDS [refractory anaemia (RA)]. Apart from marked elliptocytosis, dyshaematopoietic features were not evident in his peripheral blood or hypercellular bone marrow. After 18 months, he had progressed to RA with excess blasts in transformation. Analysis of red blood cell membrane proteins by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) showed a reduced quantity of protein 4.1 (30% of control). Deletion of chromosome 20q was identified by conventional cytogenetic analysis and fluorescence in situ hybridization. Marked elliptocytosis, persistent for more than 17 months, decreased strikingly after chemotherapy with idarubicin and Ara-C. These findings suggest that acquired elliptocytosis occurred as an unusual morphological feature of MDS, associated with abnormalities of protein 4.1 and chromosome 20q.

A novel angiogenic factor derived from Aloe vera gel: beta-sitosterol, a plant sterol

Aloe vera gel has a beneficial effect on wound healing. Because angiogenesis is an essential process in wound healing, we hypothesized that Aloe vera gel might contain potent angiogenic compounds. Here we demonstrate that Aloe vera gel and its extracts are angiogenic on the chorioallantoic membrane (CAM) of chick embryo. Out of the three compounds purified from the final fraction of Aloe vera gel, beta-sitosterol showed a potent angiogenic activity in the CAM assay. In the presence of heparin, beta-sitosterol stimulated neovascularization in the mouse Matrigel plug assay and the motility of human umbilical vein endothelial cells in an in vitro wound migration assay. Thus beta-sitosterol is a novel plant-derived angiogenic factor which may have potential pharmaceutical applications for the management of chronic wounds.

A novel angiogenic factor derived from Aloe vera gel: beta-sitosterol, a plant sterol

Aloe vera gel has a beneficial effect on wound healing. Because angiogenesis is an essential process in wound healing, we hypothesized that Aloe vera gel might contain potent angiogenic compounds. Here we demonstrate that Aloe vera gel and its extracts are angiogenic on the chorioallantoic membrane (CAM) of chick embryo. Out of the three compounds purified from the final fraction of Aloe vera gel, beta-sitosterol showed a potent angiogenic activity in the CAM assay. In the presence of heparin, beta-sitosterol stimulated neovascularization in the mouse Matrigel plug assay and the motility of human umbilical vein endothelial cells in an in vitro wound migration assay. Thus beta-sitosterol is a novel plant-derived angiogenic factor which may have potential pharmaceutical applications for the management of chronic wounds.

A method to minimize indwelling catheter calcification and bladder stones in individuals with spinal cord injury

Indwelling catheters are a common tool of bladder management in persons with high-level spinal cord injury who are unable to intermittently catheterize their bladders. Indwelling catheters are used to prevent bladder overdistension, which can trigger autonomic dysreflexia in those with injuries at or above T6. Unfortunately, indwelling catheters are prone to encrustation and can lead to the formation of bladder stones that can block the catheter and cause autonomic dysreflexia. We found that weekly catheter changes dramatically reduced catheter encrustation and stones in 2 individuals who had a history of recurrent stones despite various accepted interventions. We describe the clinical course and impact of this method in each case.

Combination Chemotherapy of Oxaliplatin, 5-Fluorouracil, and Leucovorin in 5-Fluorouracil-Pretreated Patients with Metastatic Colorectal Cancer

PURPOSE

To evaluate the efficacy and toxicity of oxaliplatin in combination with 5-fluorouracil (5-FU) and leucovorin (LV) in patients with metastatic colorectal cancer who previously treated with 5-FU-based chemotherapy.

MATERIALS AND METHODS

Between April 1999 and January 2001, thirty-two patients were enrolled in this study. Oxaliplatin 130 mg/m2 was given intravenously (IV) on day 1 as was 5-FU 500 mg/m2 IV followed by continuous infusion of 5-FU 3,000 mg/m2 and LV 100 mg/m2 for 48 hours administered every 3 weeks. Six patients had received 5-FU as an adjuvant setting and 26 patients as a palliative regimen.

RESULTS

The median age of the patients was 50 years (range; 19-69) and the dominant sites of metastasis were the liver, lung or both in 9, 5 and 2 patients respectively. In 30 evaluable patients, the overall response rate was 27% including 1 complete response and 7 partial responses. The median response duration was 28 weeks (95% confidence interval; 22~34 weeks) and the median progression free survival of all patients was 24 weeks (95% confidence interval; 15~33 weeks). A median 5 cycles (range; 2~9) and total 155 cycles were performed in 32 patients. 150 cycles were evaluable for toxicity. The most common hematologic toxicity was grade 1~2 anemia in 78 cycles (52%). Leukopenia (39%) and thrombocytopenia (23%) were fully reversible. The most common non-hematologic toxicity was nausea/vomiting (43/30%) followed by diarrhea (23%), hepatotoxicity (21%) and neurotoxicity (21%). One patient ceased therapy due to grade 4 diarrhea. No other severe toxicity interrupted this treatment.

CONCLUSION

Oxaliplatin, 5-FU and LV in combination showed significant activity in previously treated metastatic colorectal cancer with favorable toxicity.

Diabetes mellitus induces vaginal tissue fibrosis by TGF-beta 1 expression in the rat model

The commonly reported sexual problem in women with diabetes mellitus is lack of vaginal lubrication. It is our hypothesis that reduced vaginal lubrication in diabetic women may result from the structural changes of the vagina. The aim of this study was to investigate in the diabetic rat model the vaginal structures using histochemistry and the expression of TGF-beta 1 using immunohistochemistry. Twenty female Sprague-Dawley rats (200-210 g) were divided into two groups: control and experimental. The experimental group (n = 10) received intravenous injection of streptozotocin (50 mg/kg). After 4 weeks, blood glucose levels were measured, and the vagina of the rat was excised. Serial sections of the vagina were used to perform hematoxylin and eosin (H & E) and Masson's trichrome stains, and for immunohistochemistry to identify TGF-beta 1 expression. The mean blood glucose concentrations were 67 +/- 11 mg/dL (range; 50-85) in the control group and 522 +/- 61 mg/dl (range; 429-590) in the experimental group. In the diabetic animals, vaginal tissue revealed reduced epithelial layers and decreased vaginal submucosal vasculatures compared to the control animals. The collagen connective tissue in the submucosal area of the diabetic animal tissue showed a dense and irregular, distorted arrangement. The immunoreactivity of TGF-beta 1 in the diabetic animals was prominent in the collagen connective tissue, fibroblasts, and smooth muscle fibers, whereas no immunoactivity was detected in the vaginal structures of the control animals. Diabetes mellitus may induce vaginal tissue fibrosis by TGF-beta 1 expression in the rat model. This implies that reduced vaginal lubrication in the diabetic women may result from the structural changes of the vagina.

The wound-healing effect of a glycoprotein fraction isolated from aloe vera

BACKGROUND

Aloe vera has been used as a family medicine for promoting wound healing, but it is not known which component of the plant is effective for this purpose.

OBJECTIVES

To isolate and characterize the component effective in wound healing.

METHODS

Chromatography, electrophoresis and spectroscopic methods were used. The cell-proliferation activity of each component isolated was measured by a [3H]thymidine uptake assay. The cell-proliferation activity of the effective component was tested on a three-dimensional raft culture (cell culture technique by which artificial epidermis is made from keratinocytes). The effect of the active component on cell migration and wound healing was observed on a monolayer of human keratinocytes and in hairless mice.

RESULTS

A glycoprotein fraction was isolated and named G1G1M1DI2. It showed a single band on sodium dodecyl sulphate-polyacrylamide gel electrophoresis, with an apparent molecular weight of about 5.5 kDa. It exhibited significant [3H]thymidine uptake in squamous cell carcinoma cells. The effect of G1G1M1DI2 on cell migration was confirmed by accelerated wound healing on a monolayer of human keratinocytes. When this fraction was tested on a raft culture, it stimulated the formation of epidermal tissue. Furthermore, proliferation markers (epidermal growth factor receptor, fibronectin receptor, fibronectin, keratin 5/14 and keratin 1/10) were markedly expressed at the immunohistochemical level. The glycoprotein fraction enhanced wound healing in hairless mice by day 8 after injury, with significant cell proliferation.

CONCLUSIONS

It is considered that this glycoprotein fraction is involved in the wound-healing effect of aloe vera via cell proliferation and migration.

Relationship of exo-beta-D-galactofuranosidase kinetic parameters to the number of phosphodiesters in Penicillium fellutanum peptidophosphogalactomannan: enzyme purification and kinetics of glycopeptide and galactofuran chain hydrolysis

Extracellular Penicillium fellutanum exo-beta-D-galactofuranosidase, with a mass of 70 kDa, was purified to apparent homogeneity. The enzyme was used to investigate the influence of phosphodiesters of the peptidophosphogalactomannans pP(2)GM(ii) and pP(25)GM(ii) (containing 2 and 25 phosphodiester residues, respectively, per mol of polymer) on the kinetic parameters of galactofuranosyl hydrolysis of these two polymers, of 1-O-methyl-beta-D-galactofuranoside, and of two galactofuranooligosaccharides. The enzyme did not hydrolyze phosphorylated galactose residues of pP(2)GM(ii) or pP(25)GM(ii). The k(cat)/K(m) value for pP(25)GM(ii) is 1.7 x 10(3) M(-1) s(-1), that for 1-O-methyl-beta-D-galactofuranoside is 1.1 x 10(4) M(-1) s(-1), that for pP(2)GM(ii) is 1.7 x 10 (4) M(-1) s(-1), and those for 5-O-beta-D-galactofuranooligosaccharides with degrees of polymerization of 3.4 and 5.5 are 1.7 x 10(5) and 4.1 x 10(5) M(-1) s(-1), respectively. Variability in the k(cat)/K(m) values is due primarily to differences in K(m) values; the k(-1)/k(1) ratio likely provides the most influence on K(m). k(cat) increases as the degree of polymerization of galactofuranosyl residues increases. Most of the galactofuranosyl and phosphocholine residues were removed by day 8 in vivo from pP(x)GM(ii) added to day 3 cultures initiated in medium containing 2 mM phosphate but not from those initially containing 20 mM phosphate. The filtrates from day 9 cultures initiated in 2 mM inorganic phosphate in modified Raulin-Thom medium contained 0.2 mM inorganic phosphate and 2.2 U of galactofuranosidase ml(-1)h(-1). No galactofuranosidase activity but 15 mM inorganic phosphate was found in filtrates from day 9 cultures initiated in 20 mM phosphate. In vivo the rate of galactofuranosyl hydrolysis of pP(x)GM(ii) and of related polymers is proportional to the k(cat)/K(m) value of each polymer. The kinetic data show that the k(cat)/K(m) value increases as the number of phosphodiesters of pP(x)GM(ii) decreases, also resulting in an increase in the activity of exo-beta-D-galactofuranosidase.

Downregulation of Bcl-2 and activation of caspase-8 in the UVB-induced apoptosis of a cultured human melanoma cell line

PURPOSE

This study was performed to determine the effect of UV radiation on the activation of apoptosis regulatory proteins using cultured human melanoma cells.

METHODS

G361 lightly pigmented melanoma cells were irradiated with increasing doses of UVB and analyzed for an apoptotic mechanism using a cell viability test, TEM, FACS, and western blotting analysis.

RESULTS

TEM and FACS showed apoptotic features of cell death after UVB irradiation. Western blotting disclosed downregulation of Bcl-2 and the activation of caspase-9. Caspase-8, a downstream molecule of Fas/FasL interaction, was also activated. The activation of downstream molecules of both caspase-8 and caspase-9 was also demonstrated.

CONCLUSION

Our data showed that the regulation of the Bcl-2 family and caspase-8 may work together to activate a caspase-3 mediated apoptotic pathway following UVB irradiation of cultured human melanoma cells.

CP43', the isiA gene product, functions as an excitation energy dissipator in the cyanobacterium Synechococcus sp. PCC 7942

Under conditions of iron deficiency certain cyanobacteria induce a chlorophyll (Chl)-binding protein, CP43', which is encoded by the isiA gene. We have previously suggested that CP43' functions as a nonradiative dissipator of light energy. To further substantiate its functional role an isiA overexpression construct was introduced into the genome of a cyanobacterium Synechococcus sp. PCC 7942 (giving isiAoe cells). The presence of functional CP43' in isiAoe cells was confirmed by Western blot as well as by the presence of a characteristic blueshift of the red Chl a absorption peak and a notable increase in the 77 K fluorescence peak at 685 nm. Compared to wild-type cells isiAoe cells, with induced CP43', had both smaller functional antenna size and decreased yields of room temperature Chl fluorescence at various light irradiances. These observations strongly suggest that isiAoe cells, with induced CP43', have an increased capacity for dissipating light energy as heat. In agreement with this hypothesis isiAoe cells were also more resistant to photoinhibition of photosynthesis than wild-type cells. Based on these results we have further strengthened the hypothesis that CP43' functions as a nonradiative dissipator of light energy, thus protecting photosystem II from excessive excitation under iron-deficient conditions.

Biochemical characterization of a novel hypoxanthine/xanthine dNTP pyrophosphatase from Methanococcus jannaschii

A novel dNTP pyrophosphatase, Mj0226 from Methanococcus jannaschii, which catalyzes the hydrolysis of nucleoside triphosphates to the monophosphate and PPi, has been characterized. Mj0226 protein catalyzes hydrolysis of two major substrates, dITP and XTP, suggesting that the 6-keto group of hypoxanthine and xanthine is critical for interaction with the protein. Under optimal reaction conditions the k(ca)(t) /K(m) value for these substrates was approximately 10 000 times that with dATP. Neither endonuclease nor 3'-exonuclease activities were detected in this protein. Interestingly, dITP was efficiently inserted opposite a dC residue in a DNA template and four dNTPs were also incorporated opposite a hypoxanthine residue in template DNA by DNA polymerase I. Two protein homologs of Mj0226 from Escherichia coli and Archaeoglobus fulgidus were also cloned and purified. These have catalytic activities similar to Mj0226 protein under optimal conditions. The implications of these results have significance in understanding how homologous proteins, including Mj0226, act biologically in many organisms. It seems likely that Mj0226 and its homologs have a major role in preventing mutations caused by incorporation of dITP and XTP formed spontaneously in the nucleotide pool into DNA. This report is the first identification and functional characterization of an enzyme hydrolyzing non-canonical nucleotides, dITP and XTP.

Repair activities of 8-oxoguanine DNA glycosylase from Archaeoglobus fulgidus, a hyperthermophilic archaeon

Oxidative DNA damage is caused by reactive oxygen species formed in cells as by products of aerobic metabolism or of oxidative stress. The 8-oxoguanine (8-oxoG) DNA glycosylase from Archaeoglobus fulgidus (Afogg), which excises an oxidatively-damaged form of guanine, was overproduced in Escherichia coli, purified and characterized. A. fulgidus is a sulfate-reducing archaeon, which grows at between 60 and 95 degrees C, with an optimum growth at 83 degrees C. The Afogg enzyme has both DNA glycosylase and apurinic/apyrimidinic (AP) lyase activities, with the latter proceeding through a Schiff base intermediate. As expected for a protein from a hyperthermophilic organism, the enzyme activity is optimal near pH 8.5 and 60 degrees C, denaturing at 80 degrees C, and is thermally stable at high levels of salt (500mM). The Afogg protein efficiently cleaves oligomers containing 8-oxoG:C and 8-oxoG:G base pairs, and is less effective on oligomers containing 8-oxoG:T and 8-oxoG:A mispairs. While the catalytic action mechanism of Afogg protein is likely similar to the human Ogg1 (hOgg1), the DNA recognition mechanism and the basis for 8-oxoG substrate specificity of Afogg differ from that of hOgg.