A pilot screening study for low bone mass in Singaporean women using years since menopause and BMI

OBJECTIVE

Current risk assessment tools for osteoporosis have inconsistent performance across different cohorts, making them difficult for clinical practice. This study aimed to evaluate a simple screening index comprising years since menopause (YSM) and body mass index (BMI) that identifies postmenopausal Singaporean women with a greater likelihood of low bone mass.

METHODS

The study used data from 188 treatment-naïve postmenopausal women. The associations between low bone mass and different demographic variables, including age, YSM and BMI, were assessed using multivariable logistic regression. Diagnostic performance of the calculated screening index was compared to the Osteoporosis Self-Assessment Tool for Asians (OSTA) and the Fracture Risk Assessment Tool (FRAX^®).

RESULTS

YSM and BMI were significantly associated with low bone mass. The area under the receiver operating characteristic curves was 0.803 for the screening index, 0.759 for the OSTA, 0.683 for the FRAX^® (major osteoporotic fracture probability [MOFP]) and 0.647 for the FRAX^® (hip fracture probability [HFP]). Non-parametric Spearman's correlation between the screening index and the other models was 0.857 with the OSTA score, 0.694 with the FRAX^® (HFP) and 0.565 with the FRAX^® (MOFP) (p < 0.0005).

CONCLUSIONS

The diagnostic performance of the screening index comprising YSM and BMI was equivalent to the OSTA and the FRAX^®. A risk chart was developed for clinicians to identify and recommend subjects for a further dual-energy X-ray absorptiometry scan. Validation of this model in larger and more diverse cohorts is required.

TGF-β induced epithelial-mesenchymal transition in an advanced cervical tumor model by 3D printing

An advanced in vitro cervical tumor model was established by 3D printing to study the epithelial-to-mesenchymal transition (EMT), which is a very important stage of dissemination of carcinoma leading to metastatic tumors. A HeLa/hydrogel grid construct composed of gelatin, alginate, Matrigel and HeLa cells was fabricated by forced extrusion in a layer-by-layer fashion. HeLa cells rapidly proliferated, formed spheroids and presented tumorigenic characteristic in the 3D-printed structure. With the supplement of TGF-β, aggregated HeLa cells started to disintegrate, and some of them changed into fibroblast-like spindle morphology, which indicated that EMT was induced. The down-regulation of epithelial marker E-cadherin, and up-regulation of mesenchymal markers such as snail, vimentin and N-cadherin were all observed in the 3D-printed model, and performed differently in 3D and 2D models. The TGF-β induced EMT was inhibited by the treatment of disulfiram and EMT pathway inhibitor C19 in a dose dependent manner, showing great potential for future studies of a therapeutic program towards cervical tumor metastasis.

Bevacizumab combined with chemotherapy for glioblastoma: a meta-analysis of randomized controlled trials

Bevacizumab, as antibodies, were applied to inhibit tumor angiogenesis by preventing activation of vascular endothelial growth factor receptor. We analyzed four clinical trials, including 607 patients, to investigate the efficacy and safety of bevacizumab when combined with chemotherapy for the treatment of glioblastomas. Results demonstrated that bevacizumab when combined with chemotherapy improved progression-free survival (HR = 0.66; 95% CI 0.56-0.78; p < 0.00001) compared with bevacizumab or chemotherapy alone. Furthermore, overall survival showed insignificant difference between two arms (HR 0.99; 95% CI 0.8-1.21; p = 0.92). However, we found that patients treated with bevacizumab-containing therapy reported increased objective response rate (OR 1.85, 95% CI 1.17-2.93; p = 0.009), but more treatment-related adverse events (OR 1.75; 95% CI 1.09-2.83; p = 0.02).

Exosomal levels of miRNA-21 from cerebrospinal fluids associated with poor prognosis and tumor recurrence of glioma patients

Glioma is a most common type of primary brain tumors. Extracellular vesicles, in the form of exosomes, are known to mediate cell–cell communication by transporting cell-derived proteins and nucleic acids, including various microRNAs (miRNAs). Here we examined the cerebrospinal fluid (CSF) from patients with recurrent glioma for the levels of cancer-related miRNAs, and evaluated the values for prognosis by comparing the measures of CSF-, serum-, and exosome-contained miR-21 levels. Samples from seventy glioma patients following surgery were compared with those from brain trauma patients as a non-tumor control group. Exosomal miR-21 levels in the CSF of glioma patients were found significantly higher than in the controls; whereas no difference was detected in serum-derived exosomal miR-21 expression. The CSF-derived exosomal miR-21 levels correlated with tumor spinal/ventricle metastasis and the recurrence with anatomical site preference. From additional 198 glioma tissue samples, we verified that miR-21 levels associated with tumor grade of diagnosis and negatively correlated with the median values of patient overall survival time. We further used a lentiviral inhibitor to suppress miR-21 expression in U251 cells. The results showed that the levels of miR-21 target genes of PTEN, RECK and PDCD4 were up-regulated at protein levels. Therefore, we concluded that the exosomal miR-21 levels could be demonstrated as a promising indicator for glioma diagnosis and prognosis, particularly with values to predict tumor recurrence or metastasis.

Migrant Women Domestic Workers in Hong Kong, Singapore and Taiwan: A Comparative Analysis

The concentration of women in certain occupations has been the main feature characterizing the feminization of migration in the Asian region during the last two decades. A gender-sensitive approach is essential in understanding the particular vulnerability facing these migrant women workers. This paper is concerned with the situation of migrant women domestic workers in East and Southeast Asia. It discusses the context of housework that has rendered migrant women domestic workers vulnerable to abuses and violence. It compares and contrasts the legal systems in Hong Kong, Singapore and Taiwan and addresses the inadequacy of the respective legal systems in dealing with the vulnerability of these women workers. Using Hong Kong as a case, it discusses the measures that have been adopted to provide better protection for migrant labor. This paper suggests that, in order to provide effective protection for the rights of these women, it is important for respective governments to take into account the particular vulnerability facing them as a result of the context of their employment.

Advanced colorectal adenoma related gene expression signature may predict prognostic for colorectal cancer patients with adenoma-carcinoma sequence

BACKGROUND

There are still no absolute parameters predicting progression of adenoma into cancer. The present study aimed to characterize functional differences on the multistep carcinogenetic process from the adenoma-carcinoma sequence.

METHODS

All samples were collected and mRNA expression profiling was performed by using Agilent Microarray high-throughput gene-chip technology. Then, the characteristics of mRNA expression profiles of adenoma-carcinoma sequence were described with bioinformatics software, and we analyzed the relationship between gene expression profiles of adenoma-adenocarcinoma sequence and clinical prognosis of colorectal cancer.

RESULTS

The mRNA expressions of adenoma-carcinoma sequence were significantly different between high-grade intraepithelial neoplasia group and adenocarcinoma group. The biological process of gene ontology function enrichment analysis on differentially expressed genes between high-grade intraepithelial neoplasia group and adenocarcinoma group showed that genes enriched in the extracellular structure organization, skeletal system development, biological adhesion and itself regulated growth regulation, with the P value after FDR correction of less than 0.05. In addition, IPR-related protein mainly focused on the insulin-like growth factor binding proteins.

CONCLUSION

The variable trends of gene expression profiles for adenoma-carcinoma sequence were mainly concentrated in high-grade intraepithelial neoplasia and adenocarcinoma. The differentially expressed genes are significantly correlated between high-grade intraepithelial neoplasia group and adenocarcinoma group. Bioinformatics analysis is an effective way to study the gene expression profiles in the adenoma-carcinoma sequence, and may provide an effective tool to involve colorectal cancer research strategy into colorectal adenoma or advanced adenoma.

Differential gene expression profiling of gastric intraepithelial neoplasia and early-stage adenocarcinoma

AIM: To investigate the differentiated whole genome expression profiling of gastric high- and low-grade intraepithelial neoplasia and early-stage adenocarcinoma.

METHODS: Gastric specimens from an upper magnifying chromoendoscopic targeted biopsy were collected from March 2010 to May 2013. Whole genome expression profiling was performed on 19 low-grade intraepithelial neoplasia (LGIN), 20 high-grade intraepithelial neoplasia (HGIN), 19 early-stage adenocarcinoma (EGC), and 19 chronic gastritis tissue samples using Agilent 4 × 44K Whole Human Genome microarrays. Differentially expressed genes between different types of lesions were identified using an unpaired t-test and corrected with the Benjamini and Hochberg false discovery rate algorithm. A gene ontology (GO) enrichment analysis was performed using the GeneSpring software GX 12.6. The differentially expressed gene was verified using a real-time TaqMan^® PCR assay with independent tissue samples, including 26 LGIN, 15 HGIN, 14 EGC, and 20 chronic gastritis. The expression of G₀S₂ were further validated by immunohistochemical staining (IHC) in 24 LGIN, 40 HGIN, 30 EGC and 61 chronic gastritis specimens.

RESULTS: The gene expression patterns of LGIN and HGIN tissues were distinct. There were 2521 significantly differentially expressed transcripts in HGIN, with 951 upregulated and 1570 downregulated. A GO enrichment analysis demonstrated that the most striking overexpressed transcripts in HGIN compared with LGIN were in the category of metabolism, defense response, and nuclear factor κB (NF-κB) cascade. While the vast majority of transcripts had barely altered expression in HGIN and EGC tissues, only 38 transcripts were upregulated in EGC. A GO enrichment analysis revealed that the alterations of the immune response were most prominent in the progression from HGIN to EGC. It is worth noting that, compared with LGIN, 289 transcripts were expressed at higher levels both in HGIN and EGC. A characteristic gene, G₀/G₁ switch 2 (G₀S₂) was one of the 289 transcripts and related to metabolism, the immune response, and the NF-κB cascade, and its expression was validated in independent samples through real-time TaqMan^® PCR and immunohistochemical staining. In real-time PCR analysis, the expression of G₀S₂ was elevated both in HGIN and EGC compared with that in LGIN (P < 0.01 and P < 0.001, respectively). In IHC analysis, G₀S₂ immunoreactivity was detected in the cytoplasmic of neoplastic cells, but was undetectable in chronic gastritis cells. The G₀S₂ expression in HGIN was higher than that of LGIN (P = 0.012, χ² = 6.28) and EGC (P = 0.008, χ² = 6.94).

CONCLUSION: A clear biological distinction between gastric high- and low-grade intraepithelial neoplasia was identified, and provides molecular evidence for clinical application.

Probable Blastomyces dermatitidis infection in a young rat

A 21-week-old male untreated control SHR/NCrlNarl rat was found dead during an experiment. Grossly, pulmonary lesions were characterized by multifocal to coalescing firm gray-white nodules randomly scattered on the surface. Microscopically, bronchopneumonia was found with pyogranulomas containing neutrophils, macrophages, and numerous thick-walled yeast cells. Yeast cells, 5 to 25 μm in diameter, with no branching of hyphae were observed by staining with hematoxylin and eosin, Diff-Quik, and periodic acid-Schiff. Furthermore, polymerase chain reaction (PCR) using panfungal and nested PCR primers were used for detection of Blastomyces dermatitidis DNA in the lung tissue. After sequencing and matching with DNA sequences in the GenBank, the sample showed a similarity of 94.6% and 97% to Ajellomyces dermatitidis (B. dermatitidis), respectively. On the basis of these results, probable pulmonary blastomycosis was diagnosed. The origin of the infection in the colony rat is undetermined.

Ultrastructural changes of posterior lingual glands after hypoglossal denervation in hamsters

Posterior lingual glands consist of two sets of minor salivary glands that serve important functions in oral physiology. To investigate the hypothesis that the hypoglossal nerve provides sympathetic innervation to the posterior lingual glands, we examined ultrastructural changes in the glands following hypoglossal denervation. In the posterior deep lingual glands (of von Ebner), the serous acinar cells showed a decrease in the number of secretory granules and an increase in lipofuscin accumulation. The ratios of cells containing lipofuscin granules were 11.39, 36.49 and 50.46%, respectively, of the control, 3- and 7-day post-axotomy glands (P < 0.001). Intraepithelial phagocytotic activity was increased. The mucous acinar cells in the posterior superficial lingual glands (of Weber) also showed degenerative changes after hypoglossal denervation. One week after nerve transection, marked cytoplasmic vacuolation and fragmentation of organelles were frequently observed. Degenerative changes were also found in unmyelinated axons associated with the glands. We provide the first evidence of the structural and functional connections between the sympathetic component of the hypoglossal nerve and posterior lingual glands.

Amplification and overexpression of Aurora-A in esophageal squamous cell carcinoma

Aurora-A/BTAK/STK15 gene which encodes a centrosome-associated kinase is located on chromosome 20q13.2, a highly amplified region in various human tumors. Recent studies have demonstrated the overexpression and amplification of Aurora-A in many malignant human cancers. The purpose of this study was to investigate the amplification and expression of Aurora-A in esophageal squamous cell carcinoma. Amplification of Aurora-A was determined by fluorescence in situ hybridization in 7 esophageal cancer cell lines and real-time PCR in 29 esophageal cancer samples. We detected Aurora-A expression in 7 esophageal cancer cell lines and 38 esophageal cancers samples by semi-quantitative reverse transcription-PCR and Western blot hybridization. The amplification of Aurora-A was detected in 27 of 29 (93.1%) esophageal cancer samples and 6 of 7 (85.7%) cancer cell lines. Aurora-A was overexpressed in 27 of 38 (71.1%) esophageal cancer samples and all 7 esophageal cancer cell lines. We conclude that Aurora-A is amplified and overexpressed in esophageal squamous cancer.

[Expression of serum breast drug-resistance protein in predicting chemosensitivity of NSCLC]

OBJECTIVE

To investigate expression of serum breast cancer resistance protein (BCRP) in non-small cell lung cancer patient (NSCLC) and healthy adult, and its correlation with chemosensitivity as one passible value of BCRP in clinical application.

METHODS

Venous blood specimens of 44 advanced NSCLC patients and 30 healthy adults were collected. Antibody of BCRP was used to detect its expression in the experiment. Part of venous specimens were randomly selected for Western-blot, and all specimens were examined by ELISA at last. Chemotherapy response of these patients was observed in order to analyze the correlation between BCRP expression level and chemosensitivity.

RESULTS

Western blot result showed that BCRP expression can be detected both in NSCLC patient and normal adult. The expression level in NSCLC patients detected by ELISA was significantly higher than that in the healthy adults (P = 0.00); which was also significantly higher in chemo-resistant patients than that in the chemosensitive (P = 0.02) and the healthy adults (P = 0.00); however, BCRP expression in chemo-sensitive patients was not significantly different from that in the healthy adults (P = 0.08).

CONCLUSION

Breast cancer resistance protein (BCRP) is found to be expressed at high level in the serum of NSCLC patient, the intensity of BCRP expression may be correlated with chemotherapy resistance in NSCLC, and the high level expressing of BCRP may indicate resistance to the platinum-based chemotherapy regimen. Detection of serum BCRP may someday become a useful bio-marker in predicting chemosensitivity of NSCLC.

Nuclear overexpression of the E2F3 transcription factor in human lung cancer

BACKGROUND

The E2F3 transcription factor has an established role in controlling cell cycle progression. In previous studies we have provided evidence that nuclear E2F3 overexpression represents a mechanism that drives the development of human bladder cancer and that determines aggressiveness in human prostate cancer. We have proposed a model in which E2F3 overexpression co-operates with removal of the E2F inhibitor pRB to facilitate cancer development. Since small cell lung cancers (SCLC) have one of the highest reported frequencies of functional abnormalities in the pRB protein (90%) of any human cancer, we wish to assess to what extent E2F3 would be overexpressed in this and other classes of human lung cancer.

METHODS

Immunohistochemical techniques were used to assess the E2F3 status in 428 samples of lung cancers, lung carcinoids, normal bronchial epithelium and normal lung tissue.

RESULTS

E2F3 is overexpressed in 55-70% of squamous cell carcinomas and 79% of adenocarcinomas of the lung. In addition very high level expression of nuclear E2F3 is found in almost all small cell lung cancers analysed. When considered together with published data our observations indicate that co-operation between pRB functional knockouts and E2F3 overexpression may represent a mechanism of development of SCLC.

Highly sensitive determination of the methylated p16 gene in cancer patients by microchip electrophoresis

The p16 tumor suppressor gene is inactivated by promoter region hypermethylation in many types of tumor. Recent studies showed that aberrant methylation of the p16 gene is an early event in many tumors, especially in lung cancer, and may constitute a new biomarker for early detection and monitoring of prevention trials. We detected tumor-associated aberrant hypermethylation of the p16 gene in plasma and tissue DNA from 153 specimens using a modified semi-nested methylation-specific PCR (MSP) combining plastic microchip electrophoresis or slab gel electrophoresis, respectively. Specimens were from 79 lung cancer patients, 15 abdominal tumor patients, 30 positive controls and 30 negative controls. The results showed that the positive rate obtained by microchip electrophoresis was more than 26.6% higher and the same specificity was kept when compared with slab gel electrophoresis. The microchip electrophoresis can rapidly and accurately analyze the PCR products of methylated DNA and obviously improve the positive rate of diagnosis of cancer patients when compared with gel electrophoresis. This method with the high assay sensitivity might be used for detection of methylation of p16 gene and even to facilitate early diagnosis of cancer patients.

Excitonic energy shell structure of self-assembled InGaAs/GaAs quantum dots

Performing optical spectroscopy of highly homogeneous quantum dot arrays in ultrahigh magnetic fields, an unprecedently well resolved Fock-Darwin spectrum is observed. The existence of up to four degenerate electronic shells is demonstrated where the magnetic field lifts the initial degeneracies, which reappear when levels with different angular momenta come into resonance. The resulting level shifting and crossing pattern also show evidence of many-body effects such as the mixing of configurations and exciton condensation at the resonances.

[Screening of hypermethylated DNA fragments in tumor tissue derived from patients with lung cancer]

The investigations on the role of DNA methylation in carcinogenesis have been mainly focused on promoter hypermethylation of tumor suppressor genes. As a number of genes associated with cancer development may be influenced by DNA methylation, identification of these genes is of great importance for understanding the epigenetic alteration in carcinogenesis. In this study, hypermethylated regions of genomic DNA from Chinese lung cancer patients were identified by a modified methylation-sensitive arbitrarily primed PCR (MS-AP-PCR). Eight hypermethylated DNA fragments (HMDF) were separated from a PCR product region between 300 and 500bp in size. After cloning, sequencing and searching with Blast and NewCpGseek programs,the result showed that all of them were typical CpG island sequences, four fragments had 99% approximately 100% homology to regions on human chromosome 2, 7, 9 and 10, respectively,but only one revealed to be known gene. Neural Network Promoter Prediction, TSSG and TSSW programs were run to analyze possible functions of the rest 7 fragments, of which 4 were identified as candidate promoter regions, indicating that they might belong to new genes. The hypermethylated DNA fragments identified in this study might be specific epigenetic alterations in the Chinese lung cancer.

[Detection of hypermethylation of p16 gene in plasma DNA from lung cancer patients]

OBJECTIVE

To detect hyper methylation of p16 gene in plasma DNA from patients with lung cancer, and to assess its potential as a malignant marker.

METHODS

Using a modified semi-nested methylation-specific PCR (MSP), the status of methylation of the p16 was investigated in plasma DNA from 137 lung cancer patients and 112 matched tumor tissues.

RESULTS

Hypermethylation of the p16 was present in 75.2% (103/137) of the plasma samples and 80.4% (90/112) of the tumor tissues. Hypermethylation of the p16 in the plasma was detected in 77.9% squamous-cell carcinoma, 65.1% adenocarcionma, 75.1% adeno-squamous-cell carcinoma, and 91.7% small-cell lung cancer. Only in those patients whose tumor tissues had hypermethylation of p16 gene, similar changes could be detected in their plasma samples. Hypermethylation of the p16 in plasma and the corresponding tumor tissues was not significantly correlated with the clinical stage and pathological type of the tumor.

CONCLUSION

The result indicates that hypermethylation of the p16 may be a useful marker in the auxiliary diagnosis of lung cancer.

1st International Lung Cancer Conference in Beijing, October 27-30, 2002

The 1st International Lung Cancer Conference was held on October 27-30, 2002 in Beijing, China. Leaders in the field of lung cancer came from Europe, Asia, and North America to speak at the event. Over 150 Asian physicians and scientists attended as well as attendees from both Europe and the US. Topics included Primary Prevention and Tobacco Control, Screening and Early Detection, Chemotherapy and Molecular Targeted Therapies, Chemoprevention, Molecular Biology/Pathology, Radiotherapy and Surgery. This paper is a comprehensive review of the data presented at the meeting.

[Detailed mapping and clinical significance of loss of heterozygosity on 9p13-23 in laryngeal squamous cell carcinoma by microsatellite analysis]

BACKGROUND & OBJECTIVE

Microsatellites are the repeated DNA sequences scattered widely within the biological genomes and closely linked with many important genes. In carcinogenesis, microsatellites often display loss of heterozygosity(LOH) as tumor suppressor genes. Some microsatellite loci often exist in the hot spots of LOH at high frequency in some specific maligances. The tumor suppressor genes, which are associated with the development and progression of the tumor, possibly harbor in the vicinity of these hot spots. Therefore, the study of LOH by microsatellite analysis is an important way to detect the putative tumor suppressor genes. This study was designed to refine the hot spots of LOH on 9p13-23 in laryngeal squamous cell carcinoma and compare the correlation between the incidence of microsatellite LOH and the clinicopathological parameters.

METHODS

Tumor tissues were obtained from paraffin embedded sections with microdissection. Genomic DNA was extracted from tumor tissues and peripheral blood lymphocytes with the phenol-chloroform. Polymerase chain reaction(PCR) amplification and denaturing gel electrophoresis were performed on a set of 42 laryngeal squamous cell carcinoma and corresponding peripheral blood lymphocytes using 13 highly polymorphic microsatellite markers on 9p13-23. The correlation was analyzed between microsatellite LOH at the high frequency on 9p13-23 and clinicopathological characteristics in the patients with squamous cell carcinoma of larynx.

RESULTS

(1)Of the 42 laryngeal cancers, 41(97.6%) showed LOH in at least one of the microsatellite markers tested on 9p13-23. The most frequently deleted marker was D9S162 in 17 of the 19 (89.5%) informative samples. The marker D9S171, which is located on 9p21, had LOH detected in 12 of the 15 informative cases (80.0%). LOH at the D9S1748 marker (closest to the p16 gene locus) was detected in 18 of the 36 informative cases (50.0%). (2)Allelic deletion mapping revealed two minimal regions of LOH encompassing markers D9S161-D9S171 on 9p21 and IFNA-D9S162 on 9p22-23. (3) Multiple LOH (>or= 4) on 9p21-23 was found more frequently in the patients under 60 years, with supraglottic squamous cell carcinoma or cervical lymph node metastasis than those over 60 years, with glottic squamous cell carcinoma or without cervical lymph node metastasis (P< 0.01,P< 0.01,P< 0.05, respectively). On the contrary, there was no correlation between T stages or pathologic classification and the frequency of LOH on 9p21-23 in 42 squamous cell carcinoma of larynx.

CONCLUSION

These findings imply the presence of at least two putative tumor suppressor genes on 9p13-23 in laryngeal squamous cell carcinoma. Multiple genetic alterations are probably implicated in supraglottic squamous cell carcinoma with cervical lymph node metastasis in younger patients.

[Research advances on bladder cancer associated genes]

Bladder cancer is the most common urinary tumors in China. Carcinogenesis of bladder is a multistep process. Accumulation of abnormal genotypes in a long period leads to malignant phenotypes. The genes associated with bladder carcinogenesis include oncogenes (such as H-ras, FGFR3, erbB2, CCND1, mdm2), tumor suppressor genes (such as INK4A/ARF, Rb, TP53, PTEN, TSC1, PTCH, DBCCR1), and DNA mismatch repair genes, etc. In this review, the authors discussed the recent research advances on the genes associated with bladder carcinoma.

The relationship between radiologic interpretation and root tip fracture during tooth extraction performed by junior clinicians

OBJECTIVES

The purpose of this study was to analyze the relationship between root tip fracture and radiologic interpretation of root morphology on periapical radiographs during third molar extraction performed by junior clinicians.

METHODS

Before tooth extraction, periapical radiographs of 107 patients with 116 third molars were evaluated by junior clinicians, all with less than 5 years of clinical experience. Radiologic interpretations of root morphology-including number, curvature, fusion, and accessory root-were recorded before each extraction. The clinicians were also asked to estimate the possibility of root fracture on a Visual Analogue Scale before the procedure. The exact morphology of the extracted teeth was recorded after the extraction for the purpose of comparison.

RESULTS

Twenty-nine of 116 teeth extracted were not correctly interpreted in at least 1 of the morphologic categories surveyed. The average expected fracture rate of nonfractured teeth was 23.1%, whereas the average expected fracture rate of fractured teeth was a significantly higher 50.3%. Misinterpretation of root morphology on radiographs decreased with increased clinical experience. Senior residents had the lowest misinterpretation and fracture rate. Logistic regression analysis showed that fracture is most closely related to the estimated fracture rate (4.95) and is also significantly related to underestimation of root curvature (0.95; 24.56 with 2 df of chi-square, P = .0001).

CONCLUSIONS

Misinterpretation of root morphology on radiographs occurred in 25% of the teeth. Root curvature was the most misinterpreted item studied. Fracture was most closely related to the estimated fracture rate. Junior clinicians in this study expected that only 50% of the fractured teeth would fracture, reflecting a general underestimation of root tip fracture. Further study should be performed to evaluate how to increase the accuracy of root curvature interpretation.

Salicylate uniquely induces a 27-kDa protein in tubercle bacillus

Salicylate was found to uniquely induce a 27-kDa protein in Mycobacterium tuberculosis complex organisms but not in Mycobacterium smegmatis or Escherichia coli. The structural analogue antitubercular para-amino-salicylate also induced the 27-kDa protein but to a somewhat lower level than salicylate. Other structural analogues such as benzoic acid and acetyl salicylic acid (aspirin) did not induce the 27-kDa protein. Western blot analysis indicated that the 27-kDa protein was localized mainly in the cytoplasm. The 27-kDa protein was not expressed at different growth phases in the absence of salicylate. The 27-kDa protein was identified as a putative benzoquinone methyltransferase (Rv0560c), which has several homologues in the M. tuberculosis genome. The cloned 27-kDa gene was found to express constitutively in E. coli, M. smegmatis and BCG with or without salicylate.

Living-donor versus cadaveric liver transplantation for non-resectable small hepatocellular carcinoma and compensated cirrhosis: a decision analysis

BACKGROUND

Cadaveric liver transplantation is effective for nonresectable early hepatocellular carcinoma. However, the scarcity of cadaveric organs has prompted some centers to use living donors, which guarantees transplantation, but entails a risk to the donor. In the absence of controlled trials, decision analysis can be used to help explicate the tradeoffs involved when considering living donor versus cadaveric liver transplantation for nonresectable early hepatocellular carcinoma.

METHODS

Using a Markov model, a hypothetical cohort of patients with Child's A cirrhosis and a single 3.5-cm tumor received one of three strategies: 1) no transplant; 2) intent to perform cadaveric liver transplantation; or 3) living donor liver transplantation. Data were obtained from natural history and retrospective studies. All probabilities in the model were varied simultaneously using a Monte Carlo simulation.

RESULTS

Living-donor liver transplantation was the best strategy, improving life expectancy by 4.5 years compared with cadaveric liver transplantation. This strategy remained dominant even when varying severity of cirrhosis, age, tumor doubling time, tumor growth pattern, blood type, regional transplant volume, initial tumor size, and rate of progression of cirrhosis.

CONCLUSIONS

Living-donor liver transplantation should confer a substantial survival advantage for patients with compensated cirrhosis and non-resectable early stage hepatocellular carcinoma.

Multiple myeloma associated with extramedullary plasmacytoma causing nerve root compression: a case report

Multiple myeloma associated with extramedullary plasmacytoma at initial presentation is rare. We describe a 45-year-old female patient with an initial presentation of low back pain and right side L5, S1 radiculopathy. There was no evidence of vertebral involvement but an epidural tumor was found later during neurosurgical intervention. The final diagnosis was immunoglobulin G, kappa multiple myeloma complicated with spinal root compression by an extramedullary plasmacytoma. No osteolytic lesion was noted over the length of the spine. Pathology revealed high-grade plasmablastic myeloma. During the clinical course, the patient was refractory to induction chemotherapy, and there was progressive deterioration of renal function. Urinary tract infection by Morganella morganii and pulmonary infection of unknown cause developed 5 months later, and the patient died.

Interferon and ribavirin for patients with chronic hepatitis C who did not respond to previous interferon therapy: a meta-analysis of controlled and uncontrolled trials

The efficacy of interferon (IFN) combined with ribavirin for the treatment of patients with hepatitis C who failed to respond to initial IFN therapy is not well established. The primary goal of this study was to perform a systematic review of the literature evaluating the efficacy of combination therapy in nonresponders. Studies were retrieved from MEDLINE, abstracts of scientific meetings, and review of the bibliographies of retrieved studies. Controlled trials were included in the primary analysis whereas uncontrolled trials and trials reported as abstracts were included for sensitivity analysis. The primary endpoints were biochemical and virologic response. A combined estimate of the odds ratio (OR) for each endpoint was obtained by using the random effects model. The number needed to treat (NNT) was calculated by taking the inverse of the pooled risk difference. Nine controlled trials (789 patients) were identified. Six months after treatment, the overall sustained biochemical and virologic responses to 24 weeks of combination therapy were 15.2% and 13.2% with a common OR of 3.8 (95% confidence interval [CI] 2.2-6.7) and 4.9 (95% CI 2.1-11.2) compared with patients treated with IFN monotherapy. The pooled risk difference for the sustained virologic response (SVR) to combination therapy was 7% (95% CI 2-13). The NNT was 14 (95% CI 8-50), suggesting that approximately 14 patients would need to be treated with 6 months of combination therapy for 1 patient to have a SVR. A number of variables were associated with a high response rate in individual studies. Sensitivity analysis of preliminary trials suggest a higher response rate with longer duration of therapy and non-type 1 genotypes.

Recovery of low-temperature stressed E. coli O157:H7 and its susceptibility to crystal violet, bile salt, sodium chloride and ethanol

This study was conducted to investigate the alteration of some characteristics of E. coli O157:H7 subjected to various periods of storage at -5, -18 and -28 degrees C. Results revealed that the low-temperature treatments increased the susceptibility of E. coli O157:H7 to crystal violet, bile salt, sodium chloride and ethanol. In general, the susceptibility of E. coli O157:H7 subjected to storage at -18 degrees C increased most significantly. The susceptibility of E. coli O157:H7 to the tested agents increased as the period of low-temperature storage extended, regardless of storage temperature. Among the various nitrogen and carbon sources tested, tryptone and soytone were the most effective nitrogen sources, while glucose and maltose were the most effective carbon sources for the growth of the low-temperature stressed cells. When growing the stressed E. coli O157:H7 in media containing the same nitrogen source or carbon source, their lag period increased as the time of frozen storage increased. It was also noted that in general, the recovery of the low-temperature stressed E. coli O157:H7 was highest on tryptic soy agar followed by Modified eosin methylene blue agar, while recovery on MaConkey sorbitol agar and Modified MaConkey sorbitol agar was lowest.

Early pregnancy factor activity in serum of patients with surgical abortion

PROBLEM

The presence of early pregnancy factor (EPF) has been repeatedly confirmed as indispensable to successful pregnancy. However, there is as yet little reported about how surgical abortion would affect the EPF activity, owing to the induced embryo loss. The aim of this study was to pursue this among a large number of patients available in the People's Republic of China.

METHOD

Sera from aborters were collected before surgical abortion and again on the 3rd, 5th and 7th day after treatment. EPF activity was detected by rosette inhibition assay.

RESULTS

Before surgical abortion, the mean level of EPF in pregnancy sera was about the same as that of the positive control. After surgical abortion, the EPF level declined rapidly for the first 3 days and then dropped gradually within the negative control range after 5-7 days.

DISCUSSION

Quantitative study of EPF activity along temporal dimensions (duration) due to surgical abortion further promotes the efficiency to take EPF activity and its rate of change as truly index for monitoring embryonic care and development of normal pregnancy.

[Inhibitory effects of N-(4-hydroxylphenol) retinamide on transformed human bronchial epithelial cells in vitro and reconstructed human bronchial epithelium in vivo]

Precancerous lesion is one of most important steps in tumorigenesis. It has been shown that retinoids have reliable effects on controlling many kinds of animal tumor and malignant tumor cell lines in vitro, but there is no laboratory report on the biological effect of retinoids on the precancerous lesion of human lung cancer. In this study the methods including of cell serum-free culture, precancerous model of human bronchial epithelium reconstructed in rat trachea/xenotransplanted in nude mice, flowcytometry, immunohistochemistry, TUNEL and pathological observation have been used to study the biological effects of N-(4-hydroxylphenol) retinamide (4-HPR), one new kind of retinoids, on transformed human bronchial epithelial cells in vitro and premalignant human bronchial epithelium in vivo. The results showed that in the study in vitro, the proliferation of transformed human bronchial epithelial cells, the ratio of cells in S phase, and the percentage of cells that positively react to antibody Ki-67 and mpm-2 were inhibited, but apoptotic cells were induced significantly by 4-HPR exposure. At the experiment in vivo, both growth rates and precancerous grades of the reconstructed human bronchial epithelium were reduced, and apoptotic cells were also observed in epithelium after 4-HPR treatment. The results suggested that 4-HPR is one of hopeful chemopreventive medicines to lung cancer.

pncA mutations as a major mechanism of pyrazinamide resistance in Mycobacterium tuberculosis: spread of a monoresistant strain in Quebec, Canada

Pyrazinamide (PZA) is an important first-line tuberculosis drug that is part of the currently used short-course tuberculosis chemotherapy. PZA is a prodrug that has to be converted to the active form pyrazinoic acid by pyrazinamidase (PZase) activity, encoded by the pncA gene of Mycobacterium tuberculosis, and loss of PZase activity is associated with PZA resistance. To further define the genetic basis of PZA resistance and determine the frequency of PZA-resistant strains having pncA mutations, we sequenced the pncA gene from a panel of 59 PZA-resistant clinical isolates from Canada, the United States, and Korea. Two strains that did not contain pncA mutations and had positive PZase turned out to be falsely resistant. Three PZase-negative strains (MIC, >900 microgram of PZA per ml) and one PZase-positive strain (strain 9739) (MIC, >300 microgram of PZA per ml) did not have pncA mutations. The remaining 53 of the 57 PZA-resistant isolates had pncA mutations, confirming that pncA mutation is the major mechanism of PZA resistance. Various new and diverse mutations were found in the pncA gene. Interestingly, 20 PZA-monoresistant strains and 1 multidrug-resistant isolate from Quebec, Canada, all had the same pncA mutation profile, consisting of an 8-nucleotide deletion and an amino acid substitution of Arg140-->Ser. Strain typing indicated that these strains are highly related and share almost identical IS6110 patterns. These data strongly suggest the spread of a PZA-monoresistant strain, which has not previously been described.

Percutaneous transhepatic placement of metallic stents in the treatment of complicated intrahepatic biliary stricture with hepatolithiasis: a preliminary report

OBJECTIVE

We aimed to study the effect of the metallic modified Gianturco-Rosch Z-stent in the management of refractory intrahepatic long-segment biliary strictures with hepatolithiasis.

METHODS

Six symptomatic patients with hepatolithiasis and coexisting intrahepatic long-segment biliary strictures, who failed to respond to the silastic external-internal biliary stenting, were selected. The metallic modified Gianturco-Rosch Z-stent was placed via percutaneous transhepatic cholangiography at the strictured site. Patients were followed regularly to evaluate for recurrence of cholangitis, stones, or strictures.

RESULTS

No complications were observed during the procedures. No recurrent strictures or formed calculi were found in these six patients during follow-up periods of 29 to 64 months. However, cholangitis and intrahepatic biliary muddy sludge occurred at 7 and 30 months in two patients after the placement of the metallic Z-stent. Percutaneous transhepatic cholangioscopy was used to clear sludge completely.

CONCLUSIONS

Our experience suggests that the metallic stent is a well-tolerated and promising alternative in the management of refractory intrahepatic long-segment biliary strictures with hepatolithiasis. Though biliary sludge may develop, it can be detected and cleared early. Repeated surgery can thus be avoided.

Expression of cyclin D1 is correlated with poor prognosis in patients with areca quid chewing-related oral squamous cell carcinomas in Taiwan

Abnormal expression of cell cycle regulatory proteins, particularly cyclin D1, has been implicated in the pathogenesis of several types of cancer. We have examined the expression of cyclin D1 in histological sections of oral squamous cell carcinomas (SCCs) using anti-cyclin D1 antibodies with an immunoperoxidase technique. Cyclin D1 nuclear staining was observed in 73 of 88 (83%) cases of oral SCC. In 54 of these 73 (74%) cases, positive cyclin D1 staining was also found in the normal appearing epithelium immediately adjacent to the cyclin D1-positive SCCs. No significant correlation was found between the expression of cyclin D1 and the patients' age, sex, oral habits, cancer location and STNM status. The Kaplan-Meier analysis showed that patients with tumors containing more than 10% cyclin D1-positive cells had significantly shorter overall survival than those with tumors containing less than 10% cyclin D1-positive cells or with cyclin D1-negative tumors (P<0.05). Patients with positive lymph node status also had significantly shorter overall survival (P<0.01). These results indicate that cyclin D1 may play an important role in the genesis of oral SCC and may serve as an adjuvant marker of worse prognosis in patients with oral SCCs in Taiwan.

Chromosome 3 imbalances are the most frequent aberration found in non-small cell lung carcinoma

The chromosomal imbalances in nine cases of primary non-small cell lung cancer (NSCLC) and two cell lines derived from normal human bronchial epithelial (HBE) tissue were identified by comparative genomic hybridization (CGH). Gain of material from 3q and loss of 3p material were the most frequent changes in the primary tumors. Other commonly found imbalances included gain of material from 1q, 7p, 8q, 9q, 17q and 20q, and losses involving 4, 5q, 8p, 10 and 13q. High level gain was found in two cases, both encompassing the 3q23-q27 region. Loss of 3p was also found in both of the HBE cell lines suggesting that loss of one or more tumor supressor genes on 3p may be important for epithelial transformation and could be involved in the earlier stages of lung cancer development.

Congenital nasal pyriform aperture stenosis and single central maxillary incisor: CT and MRI findings

The authors report five cases of congenital nasal pyriform aperture stenosis (CNPAS). Four cases are presented as neonatal nasal obstruction and also have single central maxillary incisor (SCMI). Computed tomography examination indicates three of the SCMI are unerupted and one is erupted. The fifth case has an erupted SCMI and short stature. The associated SCMI in CNPAS is believed to be more than an isolated anomaly. Awareness of the associated features of CNPAS among the radiologist and otolaryngologist may help the diagnosis and treatment of the patient.

Expression of CD44s, CD44v5, CD44v6 and CD44v7-8 in betel quid chewing-associated oral premalignant lesions and squamous cell carcinomas in Taiwan

Aberrant expression of the cell surface adhesion molecule CD44 and its variant forms has been shown to be associated with the invasive and metastatic potential of cancer cells, and with poor prognosis in several types of cancers. Expression of CD44 standard (CD44s) and variant (CD44v) forms in oral squamous cell carcinoma (SCC), epithelial dysplasia (ED), epithelial hyperkeratosis (EH) and normal buccal mucosa (NBM) have been examined using antibodies to CD44s, CD44v5, CD44v6 and CD44v7-8. Positive CD44s, CD44v5, CD44v6 and CD44v7-8 staining was detected in all the specimens from NBM, EH and ED. Positive staining of CD44s, CD44v5, CD44v6 or CD44v7-8 was detected in 55 (88.7%), 48 (77.4%), 59 (95.2%) and 22 (35.5%) of the 62 SCC specimens, respectively. The positive staining of CD44v7-8 in oral SCC was significantly less than that in NBM (P<0.01). No significant correlation was found between CD44v7-8 expression and daily or total consumption of betel quids or cigarettes by the SCC patients. The 5-year survival rate for patients with CD44v7-8-positive tumours was significantly higher than that for the CD44v7-8-negative group (P<0.03). These results indicate that loss of CD44v7-8 expression may be a valuable factor for determining prognosis in oral SCC patients.

Molecular cytogenetic alterations in the early stage at human bronchial epithelial cell carcinogenesis

Lung carcinogenesis is a multi-step process involving activation of oncogenes and inactivation of tumor suppress genes. Many molecular and cytogenetic alterations occur in the early stages of carcinogenesis. We have developed an effective culture system for human bronchial epithelial cells and lung cancer cells. Four immortalized human bronchial epithelial cell lines were established by transfecting the epithelial cells with plasmid DNA containing the early region of SV40. Some molecular and cytogenetic alterations, such as 3p-, 2q-, 9p-, c-myc translocation t(8;14) (q23; q32), were found in one immortalized bronchial epithelial cell line M when approaching malignant transformation. An increase in cell proliferation and decrease of apoptosis were noted in the late passages of the immortalized cell line M. Some molecular cytogenetic alterations were also observed in human primary non-small cell lung cancers. Molecular cytogenetic alterations during the early stage of carcinogenesis of human bronchial epithelial cells may be useful as biomarkers for both diagnosis and intermediate endpoint of chemoprevention of lung cancer.

Establishment and characterization of a SV40T-transformed human bronchial epithelial cell line

The majority of human lung cancers originate from the carcinogenesis of bronchial epithelial cells. To study the malignant progression of human bronchial epithelial cells, we established a SV40T-transformed human bronchial epithelial cell line, and observed some biological and genetic changes of the cell line at different passages. In a 2-year culture, this cell line was approaching malignancy without obvious senescence. Cells in a later passage proliferated faster and required less growth factors than those of an early passage. After continued passaging, these cells were resistant to the terminal squamous differentiation effects of serum, and many of the cells grew anchorage independently. However, no tumor formed after cells were injected into nude mice. Some genetic alterations were found accompanying those morphological changes, such as 3p- and activation of c-myc, c-erbB-2 and bcl2, suggesting that those genetic alterations may contribute to the carcinogenesis of human bronchial epithelial cells at an early stage. This cell line should be particularly useful for studying the progression of human lung cancers.

Integration of SV40 at 12q23 in SV40-immortalized human bronchial epithelial cells

In four SV40-immortalized human bronchial epithelia] cell lines established in our laboratory, we identified the SV40 integration sites by fluorescence in situ hybridization. We found that in the late passage of all the four cell lines, SV40 integrated at 12q23. It is possible that only SV40 integration at 12q23 is necessary for the immortalization of human bronchial epithelial cells. Some DNA sequences or genes in the region, such as IGF-1, may be involved with a proliferative advantage of the cells with 12q23 SV40 integration.

2q-, a non-random chromosomal abnormality in human non-small-cell lung cancer

Many cytogenetic studies have been carried out on human lung cancer. However the chromosomal alterations in human lung cancers are often complex, making it difficult to identify some abnormal chromosomes by routine cytogenetic studies. Using FISH (fluorescence in situ hybridization), we studied the alterations of chromosome 2, 3, and 17 in four human bronchial epithelial cell lines, two human non-small-cell lung cancer (NSCLC) cell lines, and 12 primary NSCLC specimens. 2q- was found in three out of four human bronchial epithelial cell lines, two NSCLC cell lines, and three out of seven primary NSCLC specimens tested. 3p- was noted in five cases of twelve primary NSCLC patients examined. 3p- was the first cytogenetic discovery and the most prominent abnormality in lung cancer. 2q- has rarely been reported in human lung cancer but loss of heterozygosity by RFLP analysis for 2q had been reported in human NSCLC. Our results indicate that 2q- was also a non-random chromosomal abnormality in the early stage of the development of human NSCLC. There would be one or more putative tumor suppressor gene(s) on the long arm of chromosome 2. Loss of the gene(s) presumably contributes to the carcinogenesis of human non-small-cell lung cancer.

Watershed infarction of spinal cord after the embolization of bronchial artery: a case report

A case of watershed infarction in the spinal cord is reported. The patient underwent bronchial artery embolization for control of massive hemoptysis. The bronchial arteriogram was carefully examined and focused on blood supply to the spinal cord prior to embolization. Acute paraparesis followed the embolization procedure even though there was no visible spinal supply on the arteriogram. Magnetic resonance imaging showed a hyperintensity lesion over the watershed region which is located at the central portion of the upper thoracic cord. This case is reported to emphasize the significant role which angiographically invisible small vessels can play in the blood supply to the spinal cord. The vascular system of the spinal cord and the prevention of spinal cord ischemia secondary to embolization are further discussed here.

Frameshift mutation in codon 176 of the p53 gene in rat esophageal epithelial cells transformed by benzo[a]pyrene dihydrodiol

Mutations in the p53 tumor suppressor gene have been associated with exposure to environmental chemical carcinogens. Cultured rat esophageal epithelial cells were transformed in vitro by treatment with benzo[a]pyrene dihydrodiol (BP-DHD). A BP-DHD-transformed cell line and control cell lines were analyzed for mutations in the p53 gene and in the Ha-ras gene by single-strand conformation polymorphism analysis of polymerase chain reaction-amplified products and direct DNA sequencing. The deletion of one cytosine in codons 174-176 (TGCCCCCAC-->TGCCCCAC) of the p53 gene was found only in the BP-DHD-transformed cell line. The BP-DHD-transformed cells were highly invasive and tumorigenic when transplanted into syngeneic rats, whereas control lines either were nontumorigenic or formed epithelial cysts. BP-DHD-transformed cells and control lines were negative for mutations in the Ha-ras gene. Our results suggest that the tumorigenic potential of the BP-DHD-transformed cell line is associated with a frameshift mutation in codon 176 of the p53 gene but not with mutations in the Ha-ras gene. The G/C-rich codons 174-176 in the rat p53 gene may be specific targets for BP-DHD.

Melkersson-Rosenthal syndrome: a case report

The Melkersson-Rosenthal syndrome (MRS) is a rare disease which includes a triad of orofacial swelling, recurrent facial nerve paralysis and plicated tongue. MRS can still be diagnosed when any two of the conditions are present. Because of its rarity, it is usually ignored and misdiagnosed. Herein, a diabetic female patient with this syndrome, previously diagnosed as Bell's palsy, is described. This case report is presented to encourage awareness of this entity among medical practitioners. In addition, the MRS literature is reviewed with respect to incidence, etiology, clinical features, pathology, differential diagnosis and treatment.

[A study on the diagnosis of pulmonary tuberculosis and silicotuberculosis by PCR]

The sputa of 156 patients with lung disease were detected by smear, culture and PCR for mycobacterium tuberculosis. The detectable limitation was 10 fg DNA and 5 organisms. Both sensitivity and specificity of detection by PCR were much better than smear or culture techniques. Our results demonstrated that PCR technique is one of the useful tools in early and rapid diagnosis of pulmonary tuberculosis and silicotuberculosis.

In vitro transformation of rat esophageal epithelial cells by fusarin C

Fusarin C (FC) is a mutagenic and carcinogenic mycotoxin which was isolated from Fusarium moniliforme culture extracts. The Fusarium moniliforme is one of most prevalent fungi found on corn in Linxian, a high risk area for esophageal cancer. This paper reports, for the first time, the malignant transformation of rat esophageal epithelial cells induced by FC. The transformed cells showed several characteristics of transformation. Colonies were formed after seeding these transformed cells either into selective medium free of epidermal growth factor (EGF) and serum, or on semi-solid agar; there was an increase in chromosome number; the expression of c-myc and v-erb-B oncogenes was enhanced in the cells; and squamous cell carcinomas arose after inoculating the cells into nude mice. The results demonstrated transforming effect of FC on rat esophageal epithelial cells, and indicate that the abnormal expression of some oncogenes could serve as a new property of transformed cells.

[Inhibitory effect of green tea extract on promotion and related action of TPA]

Polyphenol components isolated from green tea showed strong antioxidant activity. The green tea extract (GTE) significantly inhibited the promoting effect of TPA in BALB/3T3 cell transformation assays. In in vivo experiments, GTE inhibited edema induced by TPA in mouse ear. The inhibitory effect of GTE on the induction of ornithine decarboxylase activity was also found in mouse skin treated with TPA. GTE decreased the frequency of SCE induced by oxygen radical in IAR 20 liver cells treated with hypoxanthine and xanthine oxidase. Mechanisms of the antipromoting effect of GTE are discussed. Our experimental results suggest that GTE may have some practical use in cancer prevention.

Antimutagenic activity of green tea polyphenols

For centuries green tea has been a widely consumed beverage throughout the world. It is known to contain a number of pharmacologically active compounds. In this study water extracts of green tea (WEGT) and their major constituents, green tea polyphenols (GTP), were examined for antimutagenic activity. WEGT and GTP were found to significantly inhibit the reverse mutation induced by benzo[alpha]pyrene (BP), aflatoxin B1 (AFB1), 2-aminofluorene, and methanol extracts of coal tar pitch in Salmonella typhimurium TA100 and/or TA98 in the presence of a rat-liver microsomal activation system. GTP also inhibited gene forward mutation in V79 cells treated with AFB1 and BP, and also decreased the frequency of sister-chromatid exchanges and chromosomal aberrations in V79 cells treated with AFB1. The addition of GTP during and after nitrosation of methylurea resulted in a dose-dependent inhibition of mutagenicity. Studies to define the mechanism of the antimutagenic activity of GTP suggest that it may affect carcinogen metabolism, DNA adduct formation, the interaction of ultimate carcinogen or the scavenging of free radicals.

Prevention of cytotoxicity and inhibition of intercellular communication by antioxidant catechins isolated from Chinese green tea

An antioxidant fraction of Chinese green tea (green tea antioxidant; GTA), containing several catechins, has been previously shown to inhibit 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced tumor promotion in mouse skin. In the present study, GTA was shown to have antioxidative activity toward hydrogen peroxide (H2O2) and the superoxide radical (O2-). GTA also prevented oxygen radical and H2O2-induced cytotoxicity and inhibition of intercellular communication in cultured B6C3F1 mouse hepatocytes and human keratinocytes (NHEK cells). GTA (0.05-50 micrograms/ml) prevented the killing of hepatocytes (measured by lactate dehydrogenase release) by paraquat (1-10 mM) and glucose oxidase (0.8-40 micrograms/ml) in a concentration-dependent fashion. GTA (50 micrograms/ml) also prevented the inhibition of hepatocyte intercellular communication by paraquat (5 mM), glucose oxidase (0.8 micrograms/ml), and phenobarbital (500 micrograms/ml). In addition, GTA (50 micrograms/ml) prevented the inhibition of intercellular communication in human keratinocytes by TPA (100 ng/ml). Cytotoxicity and inhibition of intercellular communication, two possible mechanisms by which tumor promoters may produce their promoting effects were therefore prevented by GTA. The inhibition of these two effects of pro-oxidant compounds may suggest a mechanism by which GTA inhibits tumor promotion in vivo.