Tuft-cell-intrinsic and -extrinsic mediators of norovirus tropism regulate viral immunity

Murine norovirus (MNoV) is a model for human norovirus and for interrogating mechanisms of viral tropism and persistence. We previously demonstrated that the persistent strain MNoV^CR6 infects tuft cells, which are dispensable for the non-persistent strain MNoV^CW3. We now show that diverse MNoV strains require tuft cells for chronic enteric infection. We also demonstrate that interferon-λ (IFN-λ) acts directly on tuft cells to cure chronic MNoV^CR6 infection and that type I and III IFNs signal together via STAT1 in tuft cells to restrict MNoV^CW3 tropism. We then develop an enteroid model and find that MNoV^CR6 and MNoV^CW3 similarly infect tuft cells with equal IFN susceptibility, suggesting that IFN derived from non-epithelial cells signals on tuft cells in trans to restrict MNoV^CW3 tropism. Thus, tuft cell tropism enables MNoV persistence and is determined by tuft cell-intrinsic factors (viral receptor expression) and -extrinsic factors (immunomodulatory signaling by non-epithelial cells).

Differential Cytokine Signatures of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and Influenza Infection Highlight Key Differences in Pathobiology

BACKGROUND

Several inflammatory cytokines are upregulated in severe coronavirus disease 2019 (COVID-19). We compared cytokines in COVID-19 versus influenza to define differentiating features of the inflammatory response to these pathogens and their association with severe disease. Because elevated body mass index (BMI) is a known risk factor for severe COVID-19, we examined the relationship of BMI to cytokines associated with severe disease.

METHODS

Thirty-seven cytokines and chemokines were measured in plasma from 135 patients with COVID-19, 57 patients with influenza, and 30 healthy controls. Controlling for BMI, age, and sex, differences in cytokines between groups were determined by linear regression and random forest prediction was used to determine the cytokines most important in distinguishing severe COVID-19 and influenza. Mediation analysis was used to identify cytokines that mediate the effect of BMI and age on disease severity.

RESULTS

Interleukin-18 (IL-18), IL-1β, IL-6, and tumor necrosis factor-α (TNF-α) were significantly increased in COVID-19 versus influenza patients, whereas granulocyte macrophage colony-stimulating factor, interferon-γ (IFN-γ), IFN-λ1, IL-10, IL-15, and monocyte chemoattractant protein 2 were significantly elevated in the influenza group. In subgroup analysis based on disease severity, IL-18, IL-6, and TNF-α were elevated in severe COVID-19, but not in severe influenza. Random forest analysis identified high IL-6 and low IFN-λ1 levels as the most distinct between severe COVID-19 and severe influenza. Finally, IL-1RA was identified as a potential mediator of the effects of BMI on COVID-19 severity.

CONCLUSIONS

These findings point to activation of fundamentally different innate immune pathways in severe acute respiratory syndrome coronavirus 2 and influenza infection, and emphasize drivers of severe COVID-19 to focus both mechanistic and therapeutic investigations.

CD300lf is the primary physiologic receptor of murine norovirus but not human norovirus

Murine norovirus (MNoV) is an important model of human norovirus (HNoV) and mucosal virus infection more broadly. Viral receptor utilization is a major determinant of cell tropism, host range, and pathogenesis. The bona fide receptor for HNoV is unknown. Recently, we identified CD300lf as a proteinaceous receptor for MNoV. Interestingly, its paralogue CD300ld was also sufficient for MNoV infection in vitro. Here we explored whether CD300lf is the sole physiologic receptor in vivo and whether HNoV can use a CD300 ortholog as an entry receptor. We report that both CD300ld and CD300lf are sufficient for infection by diverse MNoV strains in vitro. We further demonstrate that CD300lf is essential for both oral and parenteral MNoV infection and to elicit anti-MNoV humoral responses in vivo. In mice deficient in STAT1 signaling, CD300lf is required for MNoV-induced lethality. Finally, we demonstrate that human CD300lf (huCD300lf) is not essential for HNoV infection, nor does huCD300lf inhibit binding of HNoV virus-like particles to glycans. Thus, we report huCD300lf is not a receptor for HNoV.

Structural basis for murine norovirus engagement of bile acids and the CD300lf receptor

Murine norovirus (MNoV) is closely related to human norovirus (HNoV), an infectious agent responsible for acute gastroenteritis worldwide. Here we report the X-ray crystal structure of the dimeric MNoV VP1 protruding (P) domain in complex with its cellular receptor CD300lf. CD300lf binds the P domain with a 2:2 stoichiometry, engaging a cleft between the AB and DE loops of the P2 subdomain at a site that overlaps the epitopes of neutralizing antibodies. We also identify that bile acids are cofactors enhancing MNoV cell-binding and infectivity. Structures of CD300lf-P domain in complex with glycochenodeoxycholic acid (GCDCA) and lithocholic acid (LCA) reveal two bile acid binding sites at the P domain dimer interface distant from receptor binding sites. The structural determinants for receptor and bile acid binding are supported by numerous biophysical assays utilizing interface residue mutations. We find that the monomeric affinity of CD300lf for the P domain is low and is divalent cation dependent. We have also determined the crystal structure of CD300lf in complex with phosphocholine, revealing that MNoV engages its receptor in a manner mimicking host ligands including similar metal coordination. Docking of the cocomplex structures onto a cryo-EM-derived model of MNoV suggests that each virion can make multiple CD300lf engagements, and thus, infection may be driven by the avidity of cell surface clustered CD300lf. These studies identify multiple potential modulators of norovirus infection that may act to regulate the interaction between the viral capsid P domain and its cognate cellular receptor.

Tropism for tuft cells determines immune promotion of norovirus pathogenesis

Complex interactions between host immunity and the microbiome regulate norovirus infection. However, the mechanism of host immune promotion of enteric virus infection remains obscure. The cellular tropism of noroviruses is also unknown. Recently, we identified CD300lf as a murine norovirus (MNoV) receptor. In this study, we have shown that tuft cells, a rare type of intestinal epithelial cell, express CD300lf and are the target cell for MNoV in the mouse intestine. We found that type 2 cytokines, which induce tuft cell proliferation, promote MNoV infection in vivo. These cytokines can replace the effect of commensal microbiota in promoting virus infection. Our work thus provides insight into how the immune system and microbes can coordinately promote enteric viral infection.

Biological monitoring of environment exposure to safrole and the Taiwanese betel quid chewing

A rapid and sensitive biological monitoring (BM) method for assessing exposure to the environmental carcinogen safrole has been developed. The method is an isocratic high-performance liquid chromatographic (HPLC) analysis of urinary dihydroxychavicol (DHAB) and eugenol, the urinary metabolites of safrole. Good linearity, precision, and accuracy were demonstrated. A recovery of 98.8 +/- 5.4% (SD, n = 3) was found for DHAB and 84.1 +/- 3.4% (n = 3) for eugenol. The quantitation limits of the method were 8 ng for DHAB and 10 ng for eugenol. The validity of the method was demonstrated by a linear dose-response relationship observed in rats given oral doses of safrole at 30, 75, and 150 mg/kg body weight. The method was also used to monitor the environmental exposure to the Taiwanese betel quid (TBQ) chewing, because TBQ used in Taiwan not only contains areca (betel) nut, slaked lime, and catechu but also Piper betle inflorescence or its leaves. Both of the latter have a high content of safrole. The feasibility of the method to monitor TBQ chewing was demonstrated by an analysis of 153 spot human urine samples. The results showed that the p value of the nonparametric group comparison was < 0.001 for DHAB and 0.832 for eugenol. The TBQ chewers also exhibited a significantly higher rate of urinary DHAB (but not eugenol) than the nonchewers with an odd ratio of 3.47 (95% CI, 1.61-7.51). However, when only the eugenol-positive subjects were taken into analysis, the ratio rose to 24.38 (95% CI, 3.00-197.90).

Decreased white blood cell counts in semiconductor manufacturing workers in Taiwan

OBJECTIVES

To assess the systematic health effects on the liver, kidney, and haematological function tests of workers in semiconductors in Taiwan.

METHODS

926 workers of a semiconductor plant in Taiwan in July 1995 were investigated. Complete blood tests including liver, kidney, and haematological functions were available from 227 workers.

RESULTS

There was a significantly lower mean (SD) white blood cell (WBC) count in male workers of photolithography (5870 (1190)/mm(3), p=0.003) and implantation (6190 (1150)/mm(3), p=0.018) than that of male control workers (7350 (1660)/mm(3)). There was a significantly higher prevalence of leukopenia in male photolithography workers (6 of 20; 30%) than in male control workers (1 of 18; 5.6%), the crude odds ratio (OR) was 7.3 (95% confidence interval (95% CI) 1 to 55.6), and the multivariate adjusted OR was 8.1 (95% CI 0.83 to 78.3). The tests for serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT), gamma glutamyl transferase (RGT), and creatinine were not significant among male workers. Female workers in photolithography had abnormal SGPT and RGT of borderline significance, the multivariate adjusted ORs were 9.6 (95% CI 0.86 to 107) and 6.35 (95% CI 0.53 to 75.8), respectively.

CONCLUSIONS

This study suggests that leukopenia is a potential health effect in male fabrication workers of the semiconductor industry. The tasks of the process, maintenance, and equipment engineers which consisted mostly of men put them at risk for intermittent short term peak exposure to glycol ethers, ionising radiation, arsenic, or other toxins. The findings of this medical surveillance are significant; however, a further investigation of the aetiological factors and the subsequent health effects is necessary.

Humoral response to p53 in human colorectal tumors: a prospective study of 1,209 patients

p53 Antibodies (p53-Abs) have been detected in the serum of a proportion of colorectal cancer (CRC) patients. It is not yet known at which stage during colorectal tumor progression p53-Abs appear in the serum. The utility of these antibodies as markers for CRC prognosis remains to be clarified. Using a quantitative enzyme-linked immunosorbent assay, we analyzed serum samples from 998 CRC patients and from 211 patients with polyp. Levels of p53-Abs were defined as negative (<10 U/microL), low (10-76 U/microL) and high (>76 U/microL). Overall, 13.0% of CRC patients and less than 1% of polyp patients had increased serum p53-Ab levels. High p53-Ab levels were only seen in patients with invasive carcinomas. The parameters that were significantly and independently associated with a greater frequency of high p53-Ab levels were the left colon (odds ratio [OR] = 3.4; 95% CI = 1.1-10.5), the rectum (OR = 2.9; 95% CI, 1.0-8.8) and advanced lymph node metastasis (OR = 4.6; 95% CI, 2.2-9.6). In univariate analysis, patients with high p53-Ab levels had a shorter survival times than did those without (p = 0.007). However, the significant effect disappeared in a Cox regression model adjusting for sex, age, tumor location, carcinoembryonic antigen levels, gross findings, histologic grade, mucin production and TNM stage. Thus, autoantibodies against p53 occur with tumor progression in multistep colorectal carcinogenesis and increase with advanced node metastasis. Furthermore, the seemingly adverse effect of high p53-Ab levels on the survival of CRC patients may be explained by other prognostic factors.

Influence of CETP gene variation on plasma lipid levels and coronary heart disease: a survey in Taiwan

Cholesteryl ester transfer protein (CETP) transfers cholesteryl ester from high-density lipoprotein (HDL) to very low-density lipoprotein (VLDL), low-density lipoprotein (LDL) and chylomicron in exchange for triglycerides. Two CETP genetic variation and four polymorphisms are investigated by polymerase chain reaction (PCR) and restriction enzyme digestion in a population of Taiwan. The results show that a very rare variation frequency is found for CETP intron 14 splice site G-->A change. The population shows a predominant 405Ile allele (61%), 442Asp (97.7%), intron 1Taq1B(+) G allele (52%), intron 8 Msp1(-) A allele (89%) and intron 9 EcoN1(-) T allele (59.2%) in the control group. Patients with coronary heart disease (CHD) have more CETP EcoN1(+/+) GG genotype (25.3%) than the controls (13.6%) (P=0.049). The intron 1 Taq1B(-) A allele is associated with a high HDL cholesterol and apoA1 level, the EcoN1(+) G allele with a low apoA1 level and the 442Gly with both high total cholesterol and LDL cholesterol levels. Paradoxically, the 442Gly is also present with a higher frequency (5.2%) in HDL cholesterol > or =65 mg/dl group than that in the general population (2.3%) (P=0.04).

Metabolic gene polymorphism frequencies in control populations

Using the International Project on Genetic Susceptibility to Environmental Carcinogens (GSEC) database containing information on over 15,000 control (noncancer) subjects, the allele and genotype frequencies for many of the more commonly studied metabolic genes (CYP1A1, CYP2E1, CYP2D6, GSTM1, GSTT1, NAT2, GSTP, and EPHX) in the human population were determined. Major and significant differences in these frequencies were observed between Caucasians (n = 12,525), Asians (n = 2,136), and Africans and African Americans (n = 996), and some, but much less, heterogeneity was observed within Caucasian populations from different countries. No differences in allele frequencies were seen by age, sex, or type of controls (hospital patients versus population controls). No examples of linkage disequilibrium between the different loci were detected based on comparison of observed and expected frequencies for combinations of specific alleles.

Association between genetic polymorphism of tumor necrosis factor-alpha and risk of oral submucous fibrosis, a pre-cancerous condition of oral cancer

Many cytokines have been thought to play important roles in the pathogenesis of oral submucous fibrosis (OSF), an areca nut chewing-specific pre-cancerous condition characterized by the deposition of collagen in oral submucosa. Tumor necrosis factor-alpha (TNF-alpha), situated in the class III region of human leukocyte antigen (HLA), is a mediator with multiple functions, including the regulation of inflammatory reaction and transcriptions of collagen and collagenase. In total, 809 male subjects were recruited for assessment of the association of OSF with a bi-allelic promoter-region (-308) polymorphism on the TNFA gene. The high production allele, TNF2, was significantly lower among OSF subjects (n = 166) than in areca-chewing controls (n = 284). This association was independent of oral cancer status. The multivariate-adjusted odds ratio for the TNFA 11 genotype was 2.6 (95% confidence interval = 1.4-4.9; p = 0.004). The finding may imply a multifunctional etiological factor of TNF-alpha in OSF pathogenesis.

Association of aflatoxin B(1)-albumin adduct levels with hepatitis B surface antigen status among adolescents in Taiwan

Chronic hepatitis B virus (HBV) infection and aflatoxin B(1) (AFB(1)) exposure interact synergetically to induce hepatocellular carcinoma. One suggested mechanism for this interaction is the enhanced activation of AFB(1) in chronically HBV-infected individuals. Whereas no associations between chronic HBV infection and AFB(1)-albumin adducts were observed in several studies in adults, hepatitis B surface antigen (HbsAg)-positive children were found to have elevated adducts in Gambia. To assess the association between chronic HBV infection and AFB(1)-albumin adduct level in Taiwan, 200 junior high school adolescents from 20 townships were assayed for HBsAg and AFB(1)-albumin adducts. The mean AFB(1)-albumin adduct level was higher in HBsAg-positive compared with HBsAg-negative subjects. The association between HBsAg status and AFB(1)-albumin adducts remained after multivariate adjustment. This finding additionally supports the synergetic interaction between HBV and AFB(1), but the mechanism remains to be elucidated.

Intraductal papillary neoplasia of the liver associated with hepatolithiasis

Intraductal papillary growth of neoplastic biliary epithelia with a fine fibrovascular stalk (intraductal papillary neoplasia of liver [IPN-L]) resembling intraductal papillary mucinous neoplasm of pancreas is occasionally associated with hepatolithiasis. In this study, 136 cases of hepatolithiasis in Taiwan, between January 1998 and March 2000, and an additional 21 cases of IPN-L before December 1998, were examined histologically. IPN-L was found in 41 of 136 hepatolithiasis cases (30.1%). Sixty-two IPN-L cases (42 women and 20 men; age range, 59.8 +/- 10 years) were divided into 4 types (type 1, IPN-L with low-grade dysplasia, 23 cases; type 2, IPN-L with high grade dysplasia, 11 cases; type 3, IPN-L with in situ and microinvasive carcinoma, 13 cases; and type 4, IPN-L of types 2 and 3 with distinct invasive carcinoma, 15 cases). Intraductal spreading and glandular involvement were commonly observed in all types. About half of types 3 and 4 cases had mucobilia, and mucinous carcinoma was variably found in two thirds of group 4 patients. IPN-L frequently showed variable gastroenteric differentiation such as goblet cells and foveolar and colon-like metaplasia. IPN-L with goblet cells and colon-like metaplasia was frequently associated with overproduction of mucin and mucobilia (P <.01). In Japan, IPN-L was not frequent in hepatolithiasis (12 of 135 cases). In conclusion, IPN-L forms a spectrum of biliary neoplasm in hepatolithiasis. It often displays variable gastroenteric metaplasia and significant intraductal spread. IPN-L tends to progress to mucinous carcinoma. Formerly reported "mucin-producing intrahepatic cholangiocarcinoma" with a favorable prognosis is included in IPN-L.

Characteristics of mutations in the p53 gene in oral squamous cell carcinoma associated with betel quid chewing and cigarette smoking in Taiwanese

p53 mutations are etiologically associated with the development of oral squamous cell carcinomas (OSCCs) or are associated with exposure to specific carcinogens. In this study, we used PCR-single strand conformation polymorphism and DNA sequencing to analyze the conserved regions of the p53 gene (exons 5-9) in OSCC tumor specimens from 187 patients with varied histories of betel quid, tobacco and alcohol use. Ninety-one of the 187 OSCCs (48.66%) showed p53 gene mutations at exons 5-9. The incidence of p53 mutations was not associated with age, sex, TNM stage, status of cigarette smoking or betel quid chewing. However, alcohol drinkers exhibited a significantly higher incidence (57/101, 56.44%) of p53 mutations than non-users (39.53%, 34/86) (P = 0.02). The effect of alcohol on the incidence of p53 mutations was still statistically significant (RR = 2.24; 95% CI, 1.21-4.15) after adjustment for cigarette smoking and betel quid (BQ) chewing. G:C to A:T transitions were the predominant mutations observed and associated with BQ and tobacco use. Alcohol drinking could enhance these transitions. After adjustment for cigarette smoking and BQ chewing, alcohol drinking still showed an independent effect on G:C to A:T transitions (RR = 2.41; 95% CI, 1.01-5.74). These findings strongly suggest an important contributive role of tobacco carcinogens to p53 mutation in this series of Taiwanese OSCCs and alcohol might enhance these mutagenic effects. As safrole-DNA adducts have been detected in 77% (23/30) of the OSCC tissues from Taiwanese oral cancer patients with a BQ chewing history, we cannot rule out the possibility that safrole or other carcinogens present in the BQ may cause a similar pattern of mutagenesis. Determination of the role of safrole and other carcinogens present in BQ on the pattern of p53 gene mutation in OSCC will require further study.

Hepatocellular carcinoma associated with focal nodular hyperplasia. Report of a case with clonal analysis

We describe a hepatocellular carcinoma partially surrounded by focal nodular hyperplasia in a 65-year-old female patient. In order to clarify the relationship of the hepatocellular carcinoma and the adjacent focal nodular hyperplasia, clonal analysis was conducted. The clonal analysis was based on the methylation pattern of the polymorphic X-chromosome-linked androgen receptor gene (HUMARA). The allelic bands from the amplification of the focal nodular hyperplasia and of the hepatocellular carcinoma showed a significant reduction in the intensity of one of the two alleles as compared with two alleles of equal intensity in the buff coat after HhaI digestion, which indicated that these two parts were monoclonal. However, the inactivated allele in the focal nodular hyperplasia and that in the hepatocellular carcinoma were not identical. Therefore, the focal nodular hyperplasia and hepatocellular carcinoma probably derived from the clonal expansion of two different clones.

Further characterization of apolipoprotein B genetic variations in Taiwanese

Apolipoprotein B (apoB, protein; APOB, gene) is the main protein component of low-density lipoprotein (LDL) and plays an important role in blood lipid metabolism. Previously, we have reported four APOB coding regions, 5' signal peptide, and 3' repeat sequence polymorphisms in our population. In this report, we further characterize other APOB genetic variations. The results illustrate that the mutation frequencies for Arg3500Gln (1/846 alleles), Arg4019Trp (2/786 alleles), -265 C/T promoter region (0/264 alleles), and intron 2 A/G (0/450 alleles) are very low. Our population showed a frequency of 68.9% for the B4311 Ser allele. The B4311 Asn allele was associated with a higher apoB level than the Ser group (p < 0.05) in normal controls. In the normal controls, a higher B4311 Asn/Asn genotype frequency was found in the group with total cholesterol (TC) > 200 mg/dL and apoB concentration > 85 mg/dL than in the group with a TC < 200 mg/dL and apoB < 85 mg/dL (p = 0.03 for TC comparison).

The association of human papillomavirus 16/18 infection with lung cancer among nonsmoking Taiwanese women

Lung cancer is the leading cause of cancer death in Taiwanese women since 1982. High lung cancer mortality ratio of male:female in Taiwan (2:1) was observed, although less than 10% of female lung cancer patients are smokers. Until now, the etiological factor remains unknown. We hypothesize that high-risk human papillomavirus (HPV) 16/18 may be associated with lung cancer development based on high prevalence of p53 negative immunostainings in female lung tumors compared with that of male lung tumors. In this study, 141 lung cancer patients and 60 noncancer control subjects were enrolled to examine whether HPV 16/18 DNA existed in lung tumor and normal tissues by nested PCR and in situ hybridization (ISH), respectively. The concordant detection of HPV 16 and 18 DNA between nested PCR and ISH method was 73 and 85.5%, respectively. Our data showed that 77 (54.6%) of 141 lung tumors had HPV 16/18 DNA compared with 16 (26.7%; P = 0.0005) of 60 noncancer control subjects. In addition, ISH data showed that HPV 16/18 DNA was uniformly located in lung tumor cells, but not in the adjacent nontumor cells. When study subjects were stratified by gender, age, and smoking status, nonsmoking female lung cancer patients who were older than 60 years old had significantly high prevalence of HPV 16/18 infection. The odds ratio of HPV 16/18 infection of nonsmoking female lung cancer patients is much higher at 10.12 (95% confidence interval, 3.88-26.38) compared with 1.98 (95% confidence interval, 0.84-4.76) of nonsmoking male lung cancer patients. This result strongly suggests that HPV infection is associated with lung cancer development of nonsmoking female lung cancer patients. The high prevalence of HPV 16/18 infection may explain to a certain extent why Taiwanese women nonsmokers had a higher lung cancer mortality rate.

Mutations of p53 gene in human colorectal cancer: distinct frameshifts among populations

We analyzed 57 p53 gene mutations in 181 colorectal cancer patients in Taiwan and compiled data on 475 independent p53 mutations in 1,156 primary colorectal cancer patients worldwide between 1992 to 1998. Transitions at the CpG sites were observed in 31 (54%) and 232 cases (49%), respectively. Frameshift mutations occurring within exons were observed in 11 (20%) and 50 cases (10%), respectively. Among the various populations studied, colorectal cancer in Taiwan had the lowest p53 mutation rate (31%), highest frequency (20%) of frameshift mutations and the second lowest rate (13%) of transversion mutation. Based on their relation to the base runs, the 61 frameshift mutations could be grouped into 4 subclasses. After corrections were made for differences in the base number in a run, the relative mutational frequency at a base run was found to be 9- to 47-fold over that in the no-run residues. The p53 frameshift mutational spectrum found in the cases in Taiwan, with respect to hotspot sequence, was significantly different from those in the selected database (p = 0.008). These data support that the patterns of high frequency of transitions at CpG sites and low frequency of transversions in base substitutions in the p53 gene are similar regardless of patient origin. However, these data also illustrate that frameshift mutations in the p53 gene in colorectal cancer patients are sequence dependent and are distinct among populations.

Gender difference in DNA adduct levels among nonsmoking lung cancer patients

Lung cancer is the leading cause of cancer mortality in Taiwanese women. Cigarette smoking cannot explain the high lung cancer mortality in this population because less than 10% of women in Taiwan are smokers. Therefore, environmental factors other than smoking may play an important role in lung cancer development in female nonsmokers. The purpose of this study was to elucidate the role of environmental carcinogen exposure in lung cancer development in Taiwanese female nonsmokers, based on DNA adduct formation. We collected nontumorous lung tissues resected from 62 nonsmoking lung cancer patients and 20 noncancer controls to investigate whether differences in susceptibility to DNA adduct formation exist between men and women. (32)P-postlabeling and ELISA (enzyme-linked immunosorbent assay) with polyclonal antibody against BPDE (7,8-dihydroxy-anti-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene)-DNA adduct were used to evaluate DNA adduct levels in lung tissues of study subjects. Our data showed that the DNA adduct levels of lung cancer patients determined by both assays were significantly higher than those of noncancer controls (P = 0.0001 for (32)P-postlabeling; P = 0.01 for ELISA). Moreover, DNA adduct levels in females were markedly greater than those in males (P = 0.014 for (32)P-postlabeling; P = 0.001 for ELISA). The difference in DNA adduct levels could not be explained by genetic polymorphisms of cytochrome P-4501A1 (CYP1A1) or glutathione S-transferase (GSTM1), as determined by polymerase chain reaction and restriction fragment length polymorphism. These results demonstrate that lung cancer patients have a higher susceptibility to DNA damage than that of noncancer controls. In addition, differences in susceptibility to DNA damage derived from environmental carcinogen exposure were observed between male and female nonsmokers. In conclusion, high susceptibility to DNA damage in females may partially explain the high mortality rate of lung cancer in nonsmoking Taiwanese women.

Mutational analysis of the p27(kip1) gene in hepatocellular carcinoma

p27(Kip1) is an inhibitor of cyclin-dependent kinase. It has been reported that reduced p27(Kip1) expression is present in human hepatocellular carcinoma. To determine the role of p27(Kip1) in hepatocarcinogenesis, 46 cases with hepatocellular carcinomas were studied. p27(Kip1) mutation was first screened by single strand conformation polymorphism, and direct DNA sequencing was then performed on those cases with mobility shifts. Two polymorphism sites were found. One is a previously described polymorphism at codon 109 (GTC-->GGC) which was found in two cases. The second polymorphism was identified at codon 55 (GCG-->GCA) in six of the 46 cases. However, the polymorphism at codon 55 was also present in seven of 93 healthy controls (7.5%), indicating that it is not associated with a predisposition for development of hepatocellular carcinoma (Fisher's exact test, 0.05). These results show that p27(Kip1) mutation is not a frequent event in human hepatocellular carcinoma, and suggest that it may be inactivated predominantly by transcriptional and/or posttranscriptional regulation rather than genomic aberrations.

p16INK4 gene mutation and allelic loss of chromosome 9p21-22 in Taiwanese hepatocellular carcinoma

BACKGROUND

The p16INK4 (MTS1/CDNK2A) gene, located on chromosome 9p21, is an inhibitor of cyclin-dependent kinase 4. Various data have shown that it is frequently inactivated in several types of cell lines and primary human cancers.

MATERIALS AND METHODS

Thirty cases with hepatocellular carcinoma were studied for possible p16INK4 gene mutation in Taiwan. Homozygous deletion was determined using polymerase chain reaction (PCR). The p16INK4 gene mutation was first screened by single strand conformation polymorphism, then direct DNA sequencing was performed on the cases with mobility shifts. Deletion mapping of chromosome 9p21-22 was also carried out with two polymorphic microsatellite markers (D9S925 and D9S168) using PCR.

RESULTS

One of the 30 cases had homozygous deletion at exon 3 of the p16INK4 gene. Another tumor had altered electrophoresed mobility in exon 2 with G to T transversion in the first nucleotide of codon 61 by direct sequencing causing a stop codon (GAG-->TAG). At the D9S925 and D9S168 loci, six out of 24 (25%) and three out of 19 (16%) informative cases showed loss of heterozygosity, respectively.

CONCLUSION

Point mutation and homozygous deletion of the p16INK4 gene are present in a subset of hepatocellular carcinomas in Taiwan. The patterns of the p16INK4 gene alteration are, however, different from those from other regions. In addition, allelic loss on chromosome 9p21-22 is not an uncommon event in hepatocellular carcinomas. Therefore, the significance of chromosome 9p loss deserves to be extensively investigated.

Association between aminolevulinate dehydrogenase genotype and blood lead levels in Taiwan

This study was designed to evaluate the association between the aminolevulinate dehydrogenase (ALAD) genotype and blood lead levels in a general population environmentally exposed to lead. This study population of 660 subjects was secondarily sampled from the 3000 random samples of Taiwanese general population to study the distribution of blood lead levels in the Taiwanese population. A simple assay based on the polymerase chain reaction-restriction fragment length polymorphism technique was used to determine the genotype of the ALAD gene. This study found that most of the Taiwanese population was ALAD 1-1 (95.4%). Only 4.6% (30 subjects) of population were found to be 1-2 or 2-2. It has been hypothesized that the ALAD2 allele is associated with increased absorption of lead. This study found that individuals with ALAD2 alleles had 20% higher blood lead levels than persons with ALAD1 alleles (7.83 +/- 5.95 vs 6.51 +/- 5.03 micrograms/dL). However, the difference was not statistically significant, even after adjustment for other risk factors of environmental exposure. The result supports the previous finding that individuals with ALAD2 allele had higher blood lead levels. The small sample size and large amount of variation in our study may account for the insignificant association.

Physical activity, water intake and risk of colorectal cancer in Taiwan: a hospital-based case-control study

The age-adjusted mortality rates of colorectal cancer have been rising in Taiwan over the past 2 decades, and colorectal cancer is now the third leading cause of cancer mortality in the country. We conducted a hospital-based case-control study to clarify the nature of the association between physical activity, water intake and colorectal-cancer risk in Taiwan. A total of 163 subjects (aged 33-80 years) with histologically confirmed primary colorectal cancer and 163 hospital controls were enrolled during 1992. Dietary intake, physical activity and other lifestyle activities were assessed using a comprehensive food-frequency and lifestyle-activity questionnaire. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were estimated using conditional logistic-regression analysis. A strong inverse dose-response relation between increased water intake and rectal cancer was found among men after adjustment for other risk factors (p for trend = 0.0005). The OR for rectal cancer among men in the highest tertile of water intake was 0.08 (95% CI, 0.02-0.35) compared with that among men in the lowest tertile (OR = 1). Similar but not significant trends were seen among women (p = 0.29). The OR for colon cancer among men with active leisure-time physical activity was 0.19 (95% CI, 0.05-0.77) times that among sedentary men (p for trend = 0.03). However, physical activity was not associated with colon-cancer risk among women (p = 0.48). No differences in the amount of water intake were found related to level of physical activity. These findings add to the evidence that leisure-time activity may reduce colon-cancer risk, not only in high-risk but also in low-risk populations, and support the potential beneficial effect of increased water intake in reducing colorectal-cancer risk.

Physical activity, water intake and risk of colorectal cancer in Taiwan: a hospital-based case-control study

The age-adjusted mortality rates of colorectal cancer have been rising in Taiwan over the past 2 decades, and colorectal cancer is now the third leading cause of cancer mortality in the country. We conducted a hospital-based case-control study to clarify the nature of the association between physical activity, water intake and colorectal-cancer risk in Taiwan. A total of 163 subjects (aged 33-80 years) with histologically confirmed primary colorectal cancer and 163 hospital controls were enrolled during 1992. Dietary intake, physical activity and other lifestyle activities were assessed using a comprehensive food-frequency and lifestyle-activity questionnaire. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were estimated using conditional logistic-regression analysis. A strong inverse dose-response relation between increased water intake and rectal cancer was found among men after adjustment for other risk factors (p for trend = 0.0005). The OR for rectal cancer among men in the highest tertile of water intake was 0.08 (95% CI, 0.02-0.35) compared with that among men in the lowest tertile (OR = 1). Similar but not significant trends were seen among women (p = 0.29). The OR for colon cancer among men with active leisure-time physical activity was 0.19 (95% CI, 0.05-0.77) times that among sedentary men (p for trend = 0.03). However, physical activity was not associated with colon-cancer risk among women (p = 0.48). No differences in the amount of water intake were found related to level of physical activity. These findings add to the evidence that leisure-time activity may reduce colon-cancer risk, not only in high-risk but also in low-risk populations, and support the potential beneficial effect of increased water intake in reducing colorectal-cancer risk.

XRCC1 polymorphisms: effects on aflatoxin B1-DNA adducts and glycophorin A variant frequency

Hereditary genetic defects in DNA repair lead to increased risk of cancer. Polymorphisms in several DNA repair genes have been identified; however, the impact on repair phenotype has not been elucidated. We explored the relationship between polymorphisms in the DNA repair enzyme, XRCC1 (codons 194, 280, and 399), and genotoxic end points measured in two populations: (a) placental aflatoxin B1 DNA (AFB1-DNA) adducts in a group of Taiwanese maternity subjects (n = 120); and (b) somatic glycophorin A (GPA) variants in erythrocytes from a group of North Carolina smokers and nonsmokers (n = 59). AFB1-DNA adducts were measured by ELISA, and erythrocyte GPA variant frequency (NN and NO) was assessed in MN heterozygotes with a flow cytometric assay. XRCC1 genotypes were identified by PCR-RFLPs. The XRCC1 399Gln allele was significantly associated with higher levels of both AFB1-DNA adducts and GPA NN mutations. Individuals with the 399Gln allele were at risk for detectable adducts (odds ratio, 2.4; 95% confidence interval, 1.1-5.4; P = 0.03). GPA NN variant frequency was significantly higher in 399Gln homozygotes (19.6 x 10(-6)) than in Gln/Arg heterozygotes (11.4 x 10(-6); P < 0.05) or Arg/Arg homozygotes (10.1 x 10(-6); P = 0.01). No significant effects were observed for other XRCC1 polymorphisms. These results suggest that the Arg399Gln amino acid change may alter the phenotype of the XRCC1 protein, resulting in deficient DNA repair.

Increased chromosome-type chromosome aberration frequencies as biomarkers of cancer risk in a blackfoot endemic area

To examine whether biomarkers such as sister chromatid exchanges (SCEs) and chromosome aberrations (CAs) can predict cancer development, a nested case-control study was performed in a blackfoot endemic area with a known high cancer risk. A cohort of 686 residents was recruited from three villages in the blackfoot endemic area. Personal characteristics were collected, and venous blood was drawn for lymphocyte culture and stored in a refrigerator. The vital status and cancer development were followed using the National Death Registry, Cancer Registry, and Blackfoot Disease Registry. The follow-up period was from August 1991 to July 1995. During this 4-year period, 31 residents developed various types of cancer. Blood culture samples from nine of these subjects were unsuitable for experiments due to improper storage. Finally, a total of 22 cancer cases had cytogenetic samples that could be analyzed. Twenty-two control subjects were selected from those who did not develop cancer in the study period, and these subjects were matched to cases by sex, age, smoking habits, and residential area. The results showed that there was no significant difference in the frequencies of SCE and chromatid-type CAs between the case and control groups. However, the frequencies of chromosome-type CAs, e.g., chromosome-type gaps, chromosome-type breaks, chromosome-type breaks plus exchanges, total chromosome-type aberrations, and total frequencies of CAs in the case group, were significantly higher than those in the control group (P < 0.05). The odds ratio of cancer risk in subjects with more than zero chromosome-type breaks was 5.0 (95% confidence interval = 1.09-22.82) compared to those with zero chromosomal breaks. The odds ratios for more than zero chromosome-type breaks plus exchanges and a frequency of total chromosome-type aberrations of >1.007% were 11.0 and 12.0, respectively (P < 0.05). Subjects with a total CA frequency of >4.023% had a 9-fold increase for cancer risk. These results indicate that chromosome-type CAs are good biomarkers for the prediction of cancer development, whereas SCEs and chromatid-type CAs cannot predict cancer risk.

Glutathione S-transferase (GST) M1 and GST T1 genotypes and hematopoietic effects of benzene exposure

This study investigated whether or not the genotypes glutathione S-transferase theta (GST T1) and mu (GST M1) correlated with low white blood cell (WBC) count found in benzene exposed workers. We found that individuals with genotypes positive for both GST T1 and GST M1 showed the highest prevalence of low WBC [odds ratio (OR) = 4.67, P = 0.046, 95% confidence interval (CI) = 1.02-24.15] when the benzene exposure was high. Multiple logistic regression showed that benzene exposure (OR = 2.81, P = 0.062, 95% CI = 0.96-8.30) was associated with increased OR on low WBC and interactions between the benzene exposure and the genotype of GST T1 were also observed. These observations suggest that GST T1 and GST M1 may play important roles in the biotransformation of benzene, the effect which leads to its hematotoxicity.

Absence of APC gene mutation in the mutation cluster region in hepatocellular carcinoma

APC gene mutations have been demonstrated not only in colorectal carcinoma but also in a variety of human cancers. To define the possible role of mutations of the APC gene in hepatocarcinogenesis, we examined 46 pairs of hepatocellular carcinomas and corresponding non-tumorous liver tissue by polymerase chain reaction and single strand conformation polymorphism. All 46 hepatocellular carcinomas had no altered electrophoretic mobility to suggest the presence of APC gene mutation in the mutation cluster region. We also examined the possible loss of heterozygosity of APC and MCC gene loci by fragment length polymorphism analysis and by polymerase chain reaction. None of the cases showed a loss of heterozygosity at the APC and MCC gene loci. The results suggested that the possibility of APC and MCC as the gene defect in the genesis of human hepatocellular carcinoma may be very rare.

Effects on sister chromatid exchange frequency of aldehyde dehydrogenase 2 genotype and smoking in vinyl chloride workers

Vinyl chloride monomer (VCM) is a human carcinogen. However, the exact mechanism of carcinogenesis remains unclear. VCM may be metabolized by cytochrome P450 2E1 (CYP2E1), aldehyde dehydrogenase 2 (ALDH2) and glutathione S-transferases (GSTs). Thus workers with inherited variant metabolic enzyme activities may have an altered risk of genotoxicity. This study was designed to investigate which risk factors might affect sister chromatid exchange (SCE) frequency in polyvinyl chloride (PVC) workers. Study subjects were 44 male workers from three PVC factories. Questionnaires were administered to obtain detailed histories of cigarette smoking, alcohol consumption, occupations, and medications. SCE frequency in peripheral lymphocytes was determined using a standardized method, and CYP2E1, GSTM1, GSTT1 and ALDH2 genotypes were identified by the polymerase chain reaction (PCR). Analysis revealed that smoking status and exposure to VCM were significantly associated with increased SCE frequency. The presence of ALDH2 1-2/2-2 genotypes was also significantly associated with an elevation of SCE frequency (9. 5 vs. 8.1, p<0.01). However, CYP2E1, GSTM1 or GSTT1 genotypes were not significantly associated with SCE frequency. When various genotypes were considered together, combination of CYP2E1 c1c2/c2c2 with ALDH2 1-2/2-2 showed an additive effect on SCE frequency. Similar results were also found for the combination of smoking with CYP2E1, or smoking with ALDH2. These results suggest that VCM workers with ALDH2 1-2/2-2 genotypes, who also smoke, may have increased risk of DNA damage.

Hepatocellular carcinoma complicated with coexisting hepatolithiasis: pitfalls in diagnosis and management

Nineteen patients with hepatocellular carcinoma associated with hepatolithiasis were retrospectively analyzed. Eleven of the 19 patients presented with hepatolithiasis-related biliary infection. Diagnosis was erroneously assumed to be hepatolithiasis alone, liver abscess, or cholangiocarcinoma in five of 11 patients before surgery was attempted. Middle-age, male sex, liver cirrhosis, hepatitis B or C infection, abnormal alpha-fetoprotein, and negative carcinoembryonic antigen raised the suspicion of associated hepatocellular carcinoma rather than cholangiocarcinoma in patients with hepatolithiasis. Antibiotics and nonoperative methods to resolve biliary infection first, followed by hepatectomy, in selected cases, to eradicate hepatocellular carcinoma and hepatolithiasis simultaneously provides the best chance for long-term survival. Otherwise, patients often died of hepatolithiasis-related biliary sepsis rather than hepatocellular carcinoma per se in the long run.

Lung function and general illness symptoms in a semiconductor manufacturing facility

Large quantities of potent gases, dopants, photoactive chemicals (photoresists, photoinitiators), solvents, and ionizing radiation are used in the semiconductor manufacturing process, but little is known about the occurrence of respiratory disease from exposures in this industry. The purpose of this study was to assess the pulmonary risk by conducting pulmonary function tests and symptoms survey in a semiconductor plant in Taiwan. This study is part of a clinical survey conducted on 926 workers in a semiconductor plant in Taiwan in July 1995. The study items included a standard self-administered questionnaire, chest x-rays, pulmonary function tests, and physical examinations in 249 workers. There was a borderline significance of higher prevalence (P = 0.06) of restrictive lung abnormality in male photolithographic workers (4 of 21; 19.1%) than in male control workers (0 of 17; 0%), and the smoking- and age-adjusted odds ratio was 4.1 (95% confidence interval [CI], 0.41-41.6). There was a significantly higher prevalence (P = 0.02) of restrictive lung abnormality in male ion-implantation workers (5 of 19; 26.3%) than in male control workers (0 of 17; 0%), and the smoking- and age-adjusted odds ratio was 3.7 (95% CI, 0.52-26.7). There were significantly higher prevalences of airway irritation, eye irritation, headache, stress, tiredness, and poor memory in female photolithographic or etch/diffusion workers than in control workers. This study suggests that restrictive lung abnormality is a potential health effect in male silicon-wafer fabrication workers in the semiconductor industry. The tasks of male process, maintenance, and equipment engineers put them at risk for intermittent short-term peak exposure. This may account for a higher prevalence of mild restrictive lung abnormality among male engineers of photolithographic and ionimplantation sections. The findings of this medical surveillance are tentative, but they suggest that further investigation of the etiologic factors and the subsequent health effects is necessary.

Frequency of Epstein-Barr virus-associated gastric adenocarcinoma in Taiwan

Eighty-two gastric adenocarcinomas (32 intestinal and 50 diffuse type) were investigated for the presence of Epstein-Barr virus (EBV) DNA by amplifying the 78-bp fragment from the EBNA1 gene with polymerase chain reaction. EBV was detected in 17 (20.7%) of the 82 gastric tumorous specimens. Of these 17 EBV-positive cases, only one was EBV-positive in the adjacent non-tumorous tissue. EBV-positive gastric adenocarcinoma was present in 15.6 and 24.0% of the intestinal and diffuse type tumors, respectively, but within the two classes there was significant non-homogeneity by type. EBV was found more frequently in adenocarcinomas of the tubular (25%) and poorly differentiated (30.3%) types. EBV involvement was found more in male than in female patients. Eighty of the 82 tumors were also checked for the prevalence of p53 gene mutation. Of the 17 EBV-positive gastric adenocarcinomas, only two showed p53 gene mutations. The p53 mutation rate was lower in EBV-positive tumors (11.8%) than in EBV-negative tumors (25.4%).

Arsenic methylation capacity, body retention, and null genotypes of glutathione S-transferase M1 and T1 among current arsenic-exposed residents in Taiwan

In order to elucidate the relationships among arsenic methylation capacity, body retention, and genetic polymorphisms of glutathione S-transferase (GST) M1 and T1, a total of 115 study subjects were recruited from Lanyang Basin located on the northeast coast of Taiwan. Specimens of drinking water, blood, urine, hair and toenail were collected from each study subject. Urinary inorganic and methylated arsenic were speciated by high performance liquid chromatography combined with hydride-generation atomic absorption spectrometry. Arsenic concentration in hair and toenail were quantitated by atomic absorption spectrophotometry. The polymerase chain reaction was used to determine genetic polymorphisms of GST M1 and T1. Arsenic concentrations in urine, hair, and toenail of study subjects were positively correlated with arsenic levels in their drinking water. Percentages of various arsenic species in urine (mean +/- standard error (SE) were 11.8 +/- 1.0, 26.9 +/- 1.2 and 61.3 +/- 1.4, respectively, for inorganic arsenic, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA). Men and women had similar arsenic methylation capability. No associations were observed between arsenic methylation capability and arsenic content in either drinking water or urine. Ratios of arsenic contents in hair and toenail to urinary arsenic content (mean +/- standard error) were 6.2 +/- 0.7 and 16.5 +/- 1.7, respectively. Genetic polymorphisms of GST M1 and T1 were significantly associated with arsenic methylation. Subjects having the null genotype of GST M1 had an increased percentage of inorganic arsenic in urine, while those with null genotype of GST T1 had an elevated percentage of DMA in urine. Arsenic contents in hair and toenail were significantly correlated with the increase in arsenic concentrations of drinking water and urine, while no significant associations were observed between arsenic contents in hair and toenail and polymorphisms of GST M1 and T1. The relationship between arsenic methylation capability and body retention was modified by genetic polymorphisms of GST M1 and T1. Arsenic contents in hair and toenail were negatively associated with MMA percentage and positively associated with DMA percentage among subjects having null genotypes of GST M1 and T1, but not among those with non-null genotypes.

The GST T1 and CYP2E1 genotypes are possible factors causing vinyl chloride induced abnormal liver function

Vinyl chloride monomer (VCM) is hepatotoxic as well as carcinogenic in humans. There are reports that exposure to VCM seems to induce abnormal liver function, liver fibrosis, cirrhosis, portal hypertension, and angiosarcoma of the liver. In vivo, VCM is metabolized by cytochrome P450 2E1 (CYP2E1) to form the electrophilic metabolites, chloroethylene oxide (CEO) and chloroacetaldehyde (CAA), which may either cause cell damage or be further metabolized and detoxified by glutathione S-transferases (GSTs). This study investigated whether or not the genotypes CYP2E1, glutathione S-transferase theta (GST T1) and mu (GST M1) correlated with abnormal liver function found in vinyl chloride exposed workers. For this study, 251 workers from five polyvinyl chloride plants were enrolled. The workers were classified into two exposure groups (high and low) and the degree of exposure was determined based on their job titles and airborne VCM concentration. The activity of serum alanine aminotransferase (ALT) was used as the parameter of liver function. The genotypes CYP2E1, GST T1 and GST M1 were determined by polymerase chain reaction and restriction fragment length polymorphism on peripheral white blood cell DNA. Other potential risk factors were also ascertained and the confounding effect was adjusted accordingly. Stratified analyses were used to explore the correlation between the alteration of liver function and the genotypes CYP2E1, GST T1 and GST M1 among the workers exposed to different levels of VCM. The following results were obtained (1) at low VCM exposure, the odds ratio (OR) of positive GST T1 on abnormal ALT was 3.8 (95% CI 1.2-14.5) but the CYP2E1 genotype was not associated with abnormal ALT. (2) At high VCM exposure, a c2c2 CYP2E1 genotype was associated with increased OR on abnormal ALT (OR 5.4, 95% CI 0.7-35.1) and positive GST T1 was significantly associated with decreased OR on abnormal ALT (OR 0.3, 95% CI 0.1-0.9). (3) Multiple linear and logistic regression also showed strong interactions of the VCM exposure to CYP2E1 as well as to the GST T1 genotype. These observations suggest that the two genotypes, CYP2E1 and GST T1, may play important roles in the biotransformation of VCM, the effect of which leads to liver damage.

p53 gene mutation in cerebral primitive neuroectodermal tumor in Taiwan

p53 mutation has been rarely reported in cerebral primitive neuroectodermal tumors (PNET). To determine the significance of p53 mutations in the development of cerebral PNET, we studied cerebral PNET samples from 14 patients, 8 females and 6 males with a mean age of 38 years (range 10 months to 77 years) who had total or subtotal surgical resection. Histological typing of PNET with neuronal (N) and non-neuronal (NN) differentiation groups revealed 8 and 6 cases, respectively. Six (43%) of the 14 patients had p53 mutation. The p53(+) and p53(-) groups had an age range of 19-77 with a mean of 49 years and 10 months to 57 years with a mean of 30 years, respectively. p53 expression between the PNET-N and PNET-NN groups was 5 of 8 (62.5%) and 1 of 6 (16.7%), respectively. The mutations contained 3 transitions, 2 transversions and 1 frameshift; none of them occurred at the site of 'hot-spot' residues (codons 175, 248, 273). The results suggest that: (1) p53 mutation in cerebral PNET tends to show a higher incidence of neuronal differentiation and occurs in the older age group in Taiwan, (2) there was no difference in survival time between the PNET-N and PNET-NN groups (7 months and 6 months) (P = 0.54), and between p53(+) and p53(-) groups (6 months and 7 months) (P = 0.57), and (3) PNET may be an entity of a heterogenous group of tumors with different genetic mechanisms controlling their trends of differential lineage. Further studies are needed to determine the significance of p53 mutations in PNET development, especially the role of carcinogens in the genesis of PNET in Taiwan.

L-myc, GST M1 genetic polymorphism and hepatocellular carcinoma risk among chronic hepatitis B carriers

In order to assess associations between the genetic polymorphism of L-myc and glutathione S-transferase M1 (GST M1) and the risk of hepatocellular carcinoma (HCC), a total of 46 surgically treated HCC patients who were seropositive in hepatitis B surface antigen (HBsAg) and 88 HBs-Ag positive controls were recruited for this study. L-myc and GST M1 genetic polymorphism was examined using a polymerase chain reaction-based restriction fragment length polymorphism assay on DNA extracted from liver and peripheral blood samples. There was no significant difference in GST M1 genotypes between HCC patients and matched controls. A gene dosage trend of association with HCC risk was observed for L-myc genotype. The dose-response relationship remained statistically significant in the multiple logistic regression analysis.

p53 gene mutation in thyroid carcinoma

The pattern of p53 protein expression was examined in 92 cases of thyroid carcinoma. When the cases were divided into two groups with regard to their cytoplasmic staining only or nucleus staining only, the frequency of the nucleus staining group was significantly higher in the poorly differentiated carcinoma (PDC) and undifferentiated carcinoma (UDC) groups (10.5% and 25%) compared with the other groups of histologic subtype (0%). The results suggest positivity in nucleus staining for p53 may be a marker for the biologically worse carcinomas, PDC and UDC, however, tumors showing only cytoplasmic staining of p53 favor a fair prognosis. In this paper, we also elucidate the spectrum of genotypic aberrations of p53 in each histological subtype. Of 92 thyroid tumor samples analyzed, the overall frequency of p53 mutation was 8.5%. The mutations occurred in 4.35% (2/46) ot WDC, 17.2% (5/29) of PDC, and 16.7% (1/6) of oncocytic carcinoma. Two of five PDC cases and one papillary carcinoma revealed point mutations in exon 8 as follows; GTG (val) to CTG (leu) at codon 272 in case 23T, CGA (arg) to CCA (pro) at codon 306 in case of 30T, and CGG (arg) to AGG (arg) at codon 282 in case 28T. All of the p53 mutations detected were represented by single nucleotide changes including two missense and one silent mutation. In contrast to the missense mutations found in PDC, it is interesting to note that the silent mutation was checked in 28T of well differentiated papillary carcinoma. These results represents molecular evidence that p53 gene aberration associated with overexpression of the mutant form of p53 protein plays a crucial role in the biologically aggressive subtypes of thyroid carcinoma, and point mutation only was not sufficient to be a prognostic marker for the biologically aggressive malignancy of thyroid tumors. There was no p53 gene aberration found in four cases of undifferentiated carcinoma (UDC) studied. The results suggest that other unknown factors should be responsible for the aggressiveness in some UDC of thyroid carcinoma except overexpression of p53.

p53 mutations in gastric cancers from Taiwan

Mutations of the p53 gene were investigated in 80 surgical specimens of primary gastric cancer by polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) analysis. Mutations were detected in 18 tumors (22.5%) and localized to exons 5, 7 and 8. Mutations did not follow a random distribution among different subtypes, but instead clustered in the group of papillary adenocarcinomas, in which 7/12 (58.3%) cases were mutated. Positivity for p53 mutation was significantly higher in intestinal-type (37.5%) than in diffuse-type carcinomas (12.5%). These results suggest that gene alterations of p53 are not rare and may participate in the carcinogenesis of intestinal-type carcinomas of the stomach. Twenty of 21 p53 mutations were represented by single nucleotide changes, mostly missense mutations (19 events) and one nonsense mutation. Transversional mutations constitute the majority of p53 mutations (65%) and only 20% of mutations show G:C to A:T transitions. It is possible that the etiologies of gastric cancer in different geographical areas are different.

Loss of heterozygosity of APC/MCC gene in differentiated and undifferentiated gastric carcinomas in Taiwan

Recently, two genes in 5q21 involved in colon carcinogenesis, APC and MCC, were identified, and also shown to be associated with the development of esophageal and lung cancers. To determine if these genes are also involved in the development of gastric cancer, 79 primary human gastric cancers were examined for loss of heterozygosity of APC or MCC or both. Loss of APC was detected in 20% of 15 informative differentiated cases, but not in 20 informative undifferentiated cases, while loss of MCC occurred in 23.5% of 17 informative undifferentiated cases, but not in 19 informative differentiated cases. These data suggest that loss of heterozygosity of APC/MCC gene is involved in the development of gastric carcinomas, and that distinctly different molecular mechanism(s) may be responsible for the development of differentiated and undifferentiated gastric carcinomas.

On the collision-activated fragmentation of proferrioxamines: Evidence for a succinimide-mediated mechanism

The fragmentation mechanism of acyclic proferrioxamines has been studied by tandem mass spectrometry in a triple stage quadrupole mass analyzer by using activation in the collision cell as well as in the high pressure region prior to the first mass analyzer. The data suggest that proferrioxamines fragment preferentially at the hydroxamate bonds via cyclic rearrangement to succinimide derivatives. This pattern was observed most clearly for the peracetyl derivatives, in which the influence of terminal functional groups was masked. Free amino or carboxylic acid functions may modify this basic fragmentation pattern. Using hydrogen-deuterium exchange, we also were able to show that the hydrogen atoms that are "recruited" in the formation of ammonium ions are "acidic" ones from elsewhere in the molecule or the matrix. At the same time, this rules out that they originate from "activated" methylene groups, as previously proposed.

Absence of p53 gene mutation and infrequent overexpression of p53 protein in hepatoblastoma

Ten cases of hepatoblastoma were studied for overexpression of p53 protein by immunohistochemistry and for possible p53 gene mutation by single strand conformation polymorphism (SSCP) analysis and direct DNA sequencing of the polymerase chain reaction products. Only one case of the macrotrabecular type at stage IV showed overexpression of p53 protein. No DNA mobility shift was found in any of these cases studied by SSCP analysis. DNA sequencing performed on the case showing overexpression of p53 protein revealed no mutation within exons 5 to 8. The associated adrenal cortical carcinoma of the same case also showed overexpression of p53 protein, but no mutation of the p53 gene. These results indicate that mutation of the p53 gene is infrequent in hepatoblastoma. This observation supports the view that mutation of the p53 gene is not as important in the oncogenesis of childhood neoplasms as in adult cancers.

Arsenic-related Bowen's disease and paraquat-related skin cancerous lesions show no detectable ras and p53 gene alterations

We have investigated point mutations of codons 12, 13, and 61 in H-, K-, and N-ras oncogenes as well as p53 tumour suppressor gene exon 5 through exon 9 by PCR-SSCP analysis in 26 skin biopsy tissues from 16 arsenic-related Bowen's disease patients and 6 skin samples from 4 paraquat manufacturing workers. No mutation was found. These results are different from findings with UV associated skin cancers. Interestingly, a silent change at codon 27 of H-ras in one allele was detected in all 4 paraquat manufacturing workers and in 2 of 16 arsenic-related Bowen's disease patients. It is likely that the molecular mechanisms involved in arsenic and paraquat induced skin cancers differ from sunlight-related skin malignancies.

Ethnic variation in the CYP2E1 gene: polymorphism analysis of 695 African-Americans, European-Americans and Taiwanese

Human cytochrome P4502E1 (CYP2E1) is inducible by ethanol and is involved in metabolism of many known carcinogens including N-nitrosodimethylamine, butadiene, benzene, and carbon tetrachloride. A 50-fold variability in CYP2E1 enzyme activity in humans has been observed but it is unknown whether the basis for this variation is genetic or environmental. Recently, two restriction fragment length polymorphisms (RFLPs) within the CYP2E1 gene have been suggested as genetic markers of risk for cancer. The first was a Rsa I polymorphism in the 5' regulatory region that appeared to alter transcriptional activation of the gene and the second was a Dra I polymorphism located approximately 7000 bp downstream in an intron. Rare alleles at each of these loci have been associated with a reduced risk for lung cancer in Japanese and Swedish populations. We have used a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method to determine the genotype frequency for each of these CYP2E1 RFLPs in 695 individuals of Taiwanese, African-American or European-American background. Genotype and allele frequencies for Taiwanese were significantly different from those of African-Americans and European-Americans at either Rsa I or Dra I sites (p < 0.0001). Allele frequencies for African-Americans and European-Americans were significantly different at the Rsa I site (p = 0.03). The rare alleles (c2 and C) occurred at frequencies of 0.28 and 0.24 in Taiwanese, 0.01 and 0.08 in African-Americans, and 0.04 and 0.11 in European-Americans. In addition, we describe three haplotypes common to all three population samples and a fourth haplotype that was only detected in the Taiwanese population sample. This fourth haplotype may have been caused by a recombination event between these markers.(ABSTRACT TRUNCATED AT 250 WORDS)

p53 gene mutations in brain tumors in Taiwan

Mutations of the p53 gene were investigated in 116 surgically removed primary brain tumor tissues by PCR-SSCP analysis. The mutations did not follow a random distribution among the various different subtypes, but occurred in 21.0% (13/62) of astrocytomas, 13.0% (3/23) of oligodendrogliomas and 35% (7/20) 35% (7/20) of PNETs. No mutation was found in the ependymomas. The majority of mutations identified in this study were G:C to A:T or C:G to T:A transitions (56.0%, 14 of 25) and occurred most frequently (56.0%, 14 of 25) at sites of CpG dinucleotides. Interestingly, codon 158 is a new hot spot which occurred with a frequency of 16.0% (4 of 25) in the samples analyzed.

Urinary aflatoxin levels, hepatitis-B virus infection and hepatocellular carcinoma in Taiwan

Using a urinary immunoassay to measure aflatoxin metabolites, we examined the associations between exposure to aflatoxin, chronic infection with the hepatitis-B virus (HBV) and background rates of hepatocellular carcinoma (HCC) mortality in a cross-sectional survey of 250 residents from 8 areas of Taiwan with a 4-fold variation in age-adjusted HCC mortality. Specimens of fasting blood and overnight urines were used to determine HBV carrier status and excretion of aflatoxin in the subjects surveyed. While the prevalence of hepatitis-B virus carriers showed moderate variability, there was a 500-fold range in urinary aflatoxin levels. Mean log-transformed levels of aflatoxin metabolites were similar in males and females and in HBV carriers and non-carriers. In the 8 townships, HCC mortality correlated positively with both area HBV carrier prevalence and mean aflatoxin levels. The primary analyses, however, were conducted at the individual level. Each subject's aflatoxin level was treated as the response variable in a multiple regression model, and the corresponding sex-specific area HCC rate was included as a predictor along with the individual's carrier status, age and sex; alcohol consumption and cigarette smoking were also considered. In these analyses, a significant association was again observed between the marker of aflatoxin exposure and the background rate of HCC mortality. In females, the slope of the regression line was somewhat steeper in HBV carriers, but this pattern was not seen in males and formal testing yielded no statistically significant evidence of an interaction. Our findings are consistent with the hypothesis that aflatoxin plays an independent role in hepatocellular carcinoma in Taiwan.

Detection of aflatoxin B1-DNA adducts in human placenta and cord blood

Human placenta and cord blood are readily available specimens that respond to maternal environmental insult and are being used to investigate metabolism, bioactivation, and transplacental transfer of procarcinogens. Enzyme-linked immunosorbent assay was used to quantitate 120 placentas and 56 cord bloods from term, uncomplicated pregnancies at Taipei Chang Gung Memorial Hospital, Taiwan, for the presence of the imidazole ring-opened form of aflatoxin B1-DNA (AFB1-DNA) adducts. Of the 120 samples of placentas, 69 (57.5%) contained AFB1-DNA adducts in levels from 0.6 to 6.3 mumol/mol DNA. Of the 56 samples of cord bloods, 5 (8.9%) contained AFB1-DNA adducts in levels from 1.4 to 2.7 mumol/mol DNA. A higher positive rate was found in samples collected in the summer than in the winter. These results indicate that a significant number of individuals in an area of high liver cancer risk have been exposed to AFB1, and it is possible to transfer AFB1 and its metabolites to the progeny through the transplacental unit. Thus, monitoring adduct levels in human specimens may provide information not only on carcinogen exposure but also on the relationship among infection with hepatitis B/C virus, dietary exposure to AFB1, and liver cancer.