Smoking, alcohol use, dietary factors and risk of small intestinal adenocarcinoma

To investigate the role of tobacco and alcohol use and dietary factors in the etiology of small intestinal adenocarcinoma, we analyzed data from a large population-based case-control study of multi-site cancers conducted in Los Angeles County between 1975 and 1984. The present analysis included interview information on 36 small intestinal adenocarcinoma patients and 998 population controls. After adjusting for age and ethnicity, men who smoked more than 100 cigarettes during their lifetimes were at a non-significantly 3-fold increased risk for small intestinal adenocarcinoma; this association was substantially weaker in women. In men and women combined, a significant 3-fold increased risk in heavy drinkers (80+ g ethanol/day) relative to more moderate drinkers and non-drinkers was observed. Although frequent (>6 times vs. less than 2 times of intake a week) intake of foods rich in heterocyclic aromatic amines (based on the combined intake of fried bacon and ham, barbecued and/or smoked meat and smoked fish) was associated with a significant 4.5-fold increased risk of small intestinal adenocarcinoma in men; this association was not present in women. Based on 2 questions that provided a crude assessment of sugar intake, risk of small intestinal adenocarcinoma in men and women appeared to be associated with adding sugar regularly in coffee or tea and daily intake of non-diet carbonated soft drinks. When we computed total sugar intake from tea, coffee and non-diet carbonated soft drinks, there was a consistent and significant trend of increasing sugar intake and risk of small intestinal adenocarcinomas. Compared with the lowest intake level a day (<5 g), medium (5-25 g) and high intakes (>25 g) were associated with ORs of 2.5 and 3.8, respectively.

Strength of linkage disequilibrium between two vitamin D receptor markers in five ethnic groups: implications for association studies

Markers in the 3' end of the vitamin D receptor gene have recently been associated with prostate cancer risk. To evaluate the adequacy of the commonly used BsmI restriction fragment length polymorphism as a marker of this locus, we genotyped 627 individuals from five ethnic groups for this marker, as well as for a polymorphic site in the 3' untranslated region of this gene. At the latter site, we identified 12 alleles, A13 to A24, of a poly(A) microsatellite. Allele size followed a bimodal distribution with distinct short (A13-A17) and long (A18-A24) allele populations. Poly(A) allele frequency differed by ethnicity, with the frequency of short alleles being highest in non-Hispanic whites (41%), intermediate in Hispanics and African-Americans (31 and 29%, respectively), and lowest in Japanese-Americans and Chinese (8 and 9%, respectively). In each of the ethnic groups, some degree of coupling was observed between BsmI B and short poly(A) alleles and between BsmI b and long poly(A) alleles. However, the strength of the linkage disequilibrium varied by ethnicity, with departures from complete disequilibrium producing disagreement between the BsmI and poly(A) genotypes. Genotypic disagreement was lowest in Japanese-Americans and non-Hispanic whites (6 and 7%, respectively), intermediate in Chinese and Hispanics (11 and 19%, respectively), and highest among African-Americans (37%), indicating that BsmI is not a good marker for the vitamin D receptor 3' untranslated region genotype in all populations. This finding may explain contradictory results from recent association studies using the BsmI marker.

Possible relation between hypertension and cancers of the renal pelvis and ureter

To evaluate the relationship of selected medical conditions and medications with cancers of the renal pelvis and ureter, we interviewed 308 subjects with renal pelvis cancer, 194 subjects with ureter cancer and 496 control subjects in 3 areas of the United States. After controlling for the effects of smoking, age, gender and geographic residence, a history of hypertension (reported to have been diagnosed more than 5 years before interview) was associated with a small but significantly increased risk (odds ratio [OR] = 1.3; 95% confidence interval [CI], 1.0-1.8), whereas no relationship was observed with a variety of other medical conditions or medications. Stratified analysis showed that the risk associated with hypertension was twice as high among users of diuretics or other antihypertensive drugs (OR = 2.4; 95% CI, 1.1-4.9) as it was among those who never used these medications (OR = 1.2; 95% CI, 0.8-1.7). Our findings suggest that the association previously reported between hypertension and renal cell cancer may extend to cancers of the renal pelvis and ureter.

Association of prostate cancer risk with genetic polymorphisms in vitamin D receptor and androgen receptor

BACKGROUND

Prostate cancer is an increasingly common disease for which there are few well-established risk factors. Family history data suggest a genetic component; however, the majority of prostate cancer cases cannot be explained by a single-gene model. Prostate cell division is influenced by two steroid hormones, testosterone and vitamin D, the action of each being mediated by its respective receptor. The genes for the two receptors are candidates in a multigenic model for prostate cancer susceptibility.

PURPOSE

We examined genetic polymorphisms in two steroid receptors, the androgen receptor (AR) and the vitamin D receptor (VDR), in a case-control pilot study of prostate cancer.

METHODS

Fifty-seven non-Hispanic white case patients with prostate cancer and 169 non-Hispanic white control subjects were genotyped for a previously described microsatellite (CAG repeats) in the AR gene and for a newly discovered poly-A microsatellite in the 3'-untranslated region (3'UTR) of the VDR gene. To compare genotypes with respect to prostate cancer risk, we estimated odds ratios (ORs) by using logistic regression. ORs were also estimated separately for advanced and localized cases of disease. All P values resulted from two-sided tests.

RESULTS

Both the AR and the VDR polymorphisms were associated, individually and after mutual adjustment, with prostate cancer. Adjusted ORs (95% confidence intervals [CIs]) for prostate cancer were 2.10 (95% CI = 1.11-3.99) for individuals carrying an AR CAG allele with fewer than 20 repeats versus an allele with 20 or more repeats and 4.61 (95% CI = 1.34-15.82) for individuals carrying at least one long (A18 to A22) VDR poly-A allele versus two short (A14 to A17) poly-A alleles. For both the AR and VDR genes, the at-risk genotypes were more strongly associated with advanced disease than with localized disease.

CONCLUSIONS

In this pilot study, genetic variation in both the VDR and the AR genes was associated with prostate cancer, and both genes appear to preferentially confer risk for advanced disease. These two genetic risk factors, if confirmed, are among the strongest risk factors yet identified for prostate cancer.

IMPLICATIONS

These results are consistent with a multigenic model of prostate cancer susceptibility. On the basis of the joint effect of several genetic loci, one might ultimately be able to construct a risk profile to predict advanced disease, so that men whose disease is unlikely to progress to an advanced stage can possibly be spared aggressive treatment.

Follow up study of moderate alcohol intake and mortality among middle aged men in Shanghai, China

OBJECTIVE

To assess the risk of death associated with various patterns of alcohol intake.

DESIGN

Prospective study of mortality in relation to alcohol consumption at recruitment, with active annual follow up.

SETTING

Four small, geographically defined communities in Shanghai, China.

SUBJECTS

18,244 men aged 45-64 years enrolled in a prospective study of diet and cancer during January 1986 to September 1989.

MAIN OUTCOME MEASURE

All cause mortality.

RESULTS

By 28 February 1995, 1198 deaths (including 498 from cancer, 269 from stroke, and 104 from ischaemic heart disease) had been identified. Compared with lifelong non-drinkers, those who consumed 1-14 drinks a week had a 19% reduction in overall mortality (relative risk 0.81; 95% confidence interval 0.70 to 0.94) after age, level of education, and cigarette smoking were adjusted for. This protective effect was not restricted to any specific type of alcoholic drink. Although light to moderate drinking (28 or fewer drinks per week) was associated with a 36% reduction in death from ischaemic heart disease (0.64; 0.41 to 0.998), it had no effect on death from stroke, which is the leading cause of death in this population. As expected, heavy drinking (29 or more drinks per week) was significantly associated with increased risks of death from cancer of the upper aerodigestive tract, hepatic cirrhosis, and stroke.

CONCLUSIONS

Regular consumption of small amounts of alcohol is associated with lower overall mortality including death from ischaemic heart disease in middle aged Chinese men. The type of alcoholic drink does not affect this association.

Presence of antibodies to the hepatitis B surface antigen is associated with an excess risk for hepatocellular carcinoma among non-Asians in Los Angeles County, California

Hepatocellular carcinoma (HCC) exhibits a more than 50-fold variation in incidence worldwide. High-risk regions include East Asia and sub-Saharan Africa, while non-Asians in the United States constitute a low-risk population. We assessed 111 cases of histologically confirmed HCC and 128 community control subjects among non-Asians of Los Angeles County for the presence in serum of hepatitis B surface antigen (HBsAg), antibodies to HBsAg (anti-HBs), antibodies to the hepatitis B core antigen (anti-HBc), HBV DNA, and antibodies to the hepatitis C virus (anti-HCV). Anti-HCV positivity was significantly associated with a 12.6-fold increase in HCC risk (95% confidence limits = 4.7, 33.6). As expected, the presence of serum HBsAg and the presence of anti-HBc in the absence of anti-HBs were both positively associated with the risk of HCC. But most interestingly, among our study subjects, the presence of anti-HBs in the absence of HBsAg and HBV DNA (indicative of a resolved infection) was significantly related to a 4.7-fold increased risk for HCC (95% confidence limits = 2.2, 9.4). Overall, any serological evidence of prior HBV exposure was associated with a 9.4-fold elevation in HCC risk (95% confidence limits = 4.7, 18.7). The data also demonstrate a synergistic effect of HBV and HCV infections on the risk of HCC. We estimate that about 55% of HCC cases occurring in non-Asians of Los Angeles can be attributed to infection by the hepatitis B and/or C viruses.

The relative roles of hepatitis B and C viruses in the etiology of hepatocellular carcinoma in southern African blacks

BACKGROUND & AIMS

Epidemiological studies have shown the relative roles of hepatitis B and C viruses in hepatocarcinogenesis to vary considerably among populations. The aim of this study was to define the independent and interactive roles of the two viruses in the genesis of hepatocellular carcinoma in southern African blacks.

METHODS

Blood samples were taken from 231 black patients with hepatocellular carcinoma and matched controls treated at four Johannesburg hospitals. These were tested for hepatitis B surface antigen, antibodies to hepatitis C virus, and hepatitis C virus RNA.

RESULTS

Relative to individuals without serological evidence of hepatitis B or C infection, those positive for hepatitis B surface antigen alone had a statistically significant 23.3-fold increased risk for hepatocellular carcinoma, whereas those positive for hepatitis C serology alone had a statistically significant risk of 6.6. A synergistic effect on risk was evident when both hepatitis B and C markers were present (relative risk, 82.5). Hepatitis B virus alone is estimated to cause 43% of hepatocellular carcinoma in southern African blacks, hepatitis C alone 5%, and coinfection with the two viruses 20%.

CONCLUSIONS

Hepatitis B virus plays a predominant role in hepatocellular carcinogenesis in southern African blacks, with hepatitis C virus responsible for a smaller proportion of cases. Coinfection with the two viruses carries a synergistic risk of hepatocellular carcinoma formation.

In vitro activity of ofloxacin against Mycobacterium tuberculosis

For the past 3 years, ofloxacin has been widely used in treating patients with drug-resistant tuberculosis in Taiwan. To study its usefulness in treating these patients, 139 isolates of Mycobacterium tuberculosis from patients treated at the Taiwan Provincial Chronic Disease Control Bureau from September 1994 to September 1995 were tested to determine the in vitro antituberculosis activity of ofloxacin. Of these, 131 had not been previously exposed to ofloxacin, and 130 (99.2%) were susceptible to ofloxacin. Sixty-four isolates were found to be susceptible to all conventional antituberculosis drugs, and all of these were also susceptible to ofloxacin. Of the remaining 67 isolates that were resistant to one or more conventional antituberculosis drugs, 66 (98.5%) were susceptible to ofloxacin. There was no association between susceptibility to ofloxacin and susceptibility to conventional antituberculosis drugs among the isolates tested. Of the eight isolates of M. tuberculosis previously exposed to ofloxacin, seven (87.5%) were resistant. Our results indicate that patients with multidrug-resistant strains of M. tuberculosis who have not received prior ofloxacin treatment may be safely treated with ofloxacin even without knowing the result of pretreatment ofloxacin susceptibility tests. We also found that ofloxacin resistance emerges frequently. Therefore, an adequate combination of antituberculosis drugs, along with ofloxacin, should be prescribed to prevent the development of resistance to ofloxacin.

Alterations in DNA methylation are early, but not initial, events in ovarian tumorigenesis

We compared global levels of DNA methylation as well as methylation of a specific locus (MyoD1) in ovarian cystadenomas, ovarian tumours of low malignant potential (LMP) and ovarian carcinomas to investigate the association between changes in DNA methylation and ovarian tumour development. As we realized that cystadenomas showed different methylation patterns from both LMP tumours and carcinomas, we verified their monoclonal origin as a means of confirming their true neoplastic nature. High-pressure liquid chromatographic (HPLC) analyses showed that global methylation levels in LMP tumours and carcinomas were 21% and 25% lower than in cystadenomas respectively (P = 0.0001 by one-way variance analysis). Changes in the methylation status of the MyoD1 locus were not seen in any of ten cystadenomas analysed but were present in five of ten LMP tumours and in five of ten carcinomas (P = 0.03). These findings suggest that alterations in DNA methylation are absent (or at least not as extensive) in ovarian cystadenomas, but are present in LMP tumours, the phenotypic features of which are intermediate between those of benign and malignant ovarian tumours. The results also emphasize the merit of distinguishing ovarian LMP tumours from cystadenomas, in spite of their similar clinical characteristics.

An apparent lack of association between Helicobacter pylori infection and risk of gastric cancer in China

Several prospective studies have shown a significant association between Helicobacter pylori seropositivity and the risk of gastric cancer. Only a small proportion of H. pylori-infected individuals will, however, develop gastric cancer, and it is unclear what effects other factors, such as diet, might have on the risk of cancer. Eighty-seven subjects with gastric cancer were identified during the first 6 years of follow-up (mean 2.4 years) of a cohort of middle-aged men from Shanghai, China. They were matched with 261 cancer-free controls, and serum samples from all subjects, obtained at recruitment, were assayed for anti-H. pylori IgG antibodies. Questionnaire data provided information on a wide range of socio-demographic life-style and dietary variables. H. pylori seropositivity rates in the cases and controls were 54% and 56%, respectively. Neither the overall risk of developing gastric cancer nor the risk of developing non-cardia gastric cancer was significantly associated with prior M. pylori seropositivity. Adjustment for any of the other medical, dietary or life-style variables studied had little effect on the risk of developing non-cardia gastric cancer; simultaneous adjustment for all of these factors yielded an odds ratio of 1.17. The results do not support the hypothesis that H. pylori plays a role in the process of gastric carcinogenesis in China. It is possible that this is an artefact resulting from the relatively short follow-up period to date.

Bladder cancer epidemiology and pathogenesis

The two major causes of bladder cancer, cigarette smoking and occupational exposure to arylamines, have been recognized for 4 decades. Recently, attention has turned increasingly toward molecular approaches that can help predict which individuals exposed to these factors are at greatest risk of developing bladder cancer and can help explain the wide variation in bladder cancer risk among populations with similar prevalences of exposure to these two known causes. The mechanism for the relationship between smoking and bladder cancer risk has not yet been fully elucidated, but most likely is due to the presence in cigarette smoke of low levels of the same carcinogenic arylamines known to induce bladder cancer in occupational settings. These arylamines undergo metabolic transformation and the activated forms can form adducts with DNA, a probable essential step in the carcinogenic process. Alternatively, these arylamines can be detoxified. Two of the enzymes involved in this detoxification, glutathione S transferase mu and N-acetyltransferase, are genetically controlled. There is now ample epidemiological evidence that variations in the genes that code for these enzymes can affect bladder cancer risk among individuals exposed to arylamines. Levels of arylamine adducts are strongly correlated with cigarette "dose" and can be substantially modified by these detoxifying enzymes.

An apparent lack of association between Helicobacter pylori infection and risk of gastric cancer in China

Several prospective studies have shown a significant association between Helicobacter pylori seropositivity and the risk of gastric cancer. Only a small proportion of H. pylori-infected individuals will, however, develop gastric cancer, and it is unclear what effects other factors, such as diet, might have on the risk of cancer. Eighty-seven subjects with gastric cancer were identified during the first 6 years of follow-up (mean 2.4 years) of a cohort of middle-aged men from Shanghai, China. They were matched with 261 cancer-free controls, and serum samples from all subjects, obtained at recruitment, were assayed for anti-H. pylori IgG antibodies. Questionnaire data provided information on a wide range of socio-demographic life-style and dietary variables. H. pylori seropositivity rates in the cases and controls were 54% and 56%, respectively. Neither the overall risk of developing gastric cancer nor the risk of developing non-cardia gastric cancer was significantly associated with prior M. pylori seropositivity. Adjustment for any of the other medical, dietary or life-style variables studied had little effect on the risk of developing non-cardia gastric cancer; simultaneous adjustment for all of these factors yielded an odds ratio of 1.17. The results do not support the hypothesis that H. pylori plays a role in the process of gastric carcinogenesis in China. It is possible that this is an artefact resulting from the relatively short follow-up period to date.

Breast cancer and hormonal contraceptives: further results. Collaborative Group on Hormonal Factors in Breast Cancer

The Collaborative Group on Hormonal Factors in Breast Cancer has brought together and reanalysed the worldwide epidemiological evidence on breast cancer risk and use of hormonal contraceptives. Original data from 54 studies, representing about 90% of the information available on the topic, were collected, checked and analysed centrally. The 54 studies were performed in 26 countries and include a total of 53,297 women with breast cancer and 100,239 women without breast cancer. The studies were varied in their design, setting and timing. Most information came from case-control studies with controls chosen from the general population; most women resided in Europe or North America and most cancers were diagnosed during the 1980s. Overall 41% of the women with breast cancer and 40% of the women without breast cancer had used oral contraceptives at some time; the median age at first use was 26 years, the median duration of use was 3 years, the median year of first use was 1968, the median time since first use was 16 years, and the median time since last use was 9 years. The main findings, summarised elsewhere, are that there is a small increase in the risk of having breast cancer diagnosed in current users of combined oral contraceptives and in women who had stopped use in the past 10 years but that there is no evidence of an increase in the risk more than 10 years after stopping use. In addition, the cancers diagnosed in women who had used oral contraceptives tended to be less advanced clinically than the cancers diagnosed in women who had not used them. Despite the large number of possibilities investigated, few factors appeared to modify the main findings either in recent or in past users. For recent users who began use before age 20 the relative risks are higher than for recent users who began at older ages. For women whose use of oral contraceptives ceased more than 10 years before there was some suggestion of a reduction in breast cancer risk in certain subgroups, with a deficit of tumors that had spread beyond the breast, especially among women who had used preparations containing the highest doses of oestrogen and progestogen. These findings are unexpected and need to be confirmed. Although these data represent most of the epidemiological evidence on the topic to date, there is still insufficient information to comment reliably about the effects of specific types of oestrogen or of progestogen. What evidence there is suggests, however, no major differences in the effects for specific types of oestrogen or of progestogen and that the pattern of risk associated with use of hormonal contraceptives containing progestogens alone may be similar to that observed for preparations containing both oestrogens and progestogens. On the basis of these results, there is little difference between women who have and have not used combined oral contraceptives in terms of the estimated cumulative number of breast cancers diagnosed during the period from starting use up to 20 years after stopping. The cancers diagnosed in women who have used oral contraceptives are, however, less advanced clinically than the cancers diagnosed in never users. Further research is needed to establish whether the associations described here are due to earlier diagnosis of breast cancer in women who have used oral contraceptives, to the biological effects of the hormonal contraceptives or to a combination of both. Little information is as yet available about the effects on breast cancer risk of oral contraceptive use that ceased more than 20 years before and as such data accumulate it will be necessary to re-examine the worldwide evidence.

Low prevalence of hepatitis C infection in hepatocellular carcinoma (HCC) cases and population controls in Guangxi, a hyperendemic region for HCC in the People's Republic of China

Southern Guangxi, China has one of the highest incidences of hepatocellular carcinoma (HCC) in the world. Serum samples collected from subjects of an earlier case-control study (39 cases, 41 controls) and from a random sampling of a residential male cohort (n = 100) were tested for antibodies for the hepatitis C virus (anti-HCV) using ELISA version 2.0 with confirmation by RIBA version 2.0. Only one of 141 (0.7%, upper 95% confidence limit, 3.2%) control subjects and none of 39 (upper 95% confidence limit, 6.07%) HCC cases tested positive for anti-HCV. Our results indicate that hepatitis C infection is not an important environmental determinant of HCC risk in this hyperendemic region.

Morbidity and mortality in relation to cigarette smoking in Shanghai, China. A prospective male cohort study

OBJECTIVE

To evaluate prospectively the health risk of cigarette smoking in middle-aged men in Shanghai, China.

DESIGN

Prospective cohort study with annual follow-up.

PARTICIPANTS

A total of 18 244 male residents of Shanghai, China, enrolled in the study during January 1, 1986, through September 30, 1989, and actively followed via annual visits.

RESULTS

By September 30, 1993, 852 deaths and 554 incident cancer cases were identified during the follow-up period, which averaged 5.4 years per subject. The overall incidence rate for cancer was 568 per 100 000 man-years, with the 3 leading sites being lung (146/100 000), stomach (116/100 000), and liver (81/100 000). Forty-one percent of all deaths were from cancer. Stroke was the most frequent cause of death unrelated to cancer, with an age-adjusted rate 4.2 times higher than that of US white men (201/100 000 vs 48/100 000), followed by ischemic heart disease, with an age-adjusted rate one-fifth that of US white men (69/100 000 vs 366/100 000). Compared with lifelong nonsmokers, the relative risks in heavy smokers (20 or more cigarettes per day) after adjustment for alcohol consumption were 2.2 for any incident cancer, 9.4 for incident lung cancer, 6.7 for head and neck cancer, and 1.8 for liver cancer. In terms of mortality, heavy smokers were at a 60% greater risk of death relative to lifelong nonsmokers; there was a 2.3-fold excess risk of death from cancer and 2-fold to 3-fold excess risk of death from heart disease.

CONCLUSIONS

Cigarette smoking is an important predictor of risk of cancer and mortality in men in Shanghai. Among the study subjects, 36% of all cases of cancer and 21% of all deaths could be attributed to cigarette smoking.

Mutational analysis of the input domain of the VirA protein of Agrobacterium tumefaciens

The transmembrane sensor protein VirA activates VirG in response to high levels of acetosyringone (AS). In order to respond to low levels of AS, VirA requires the periplasmic sugar-binding protein ChvE and monosaccharides released from plant wound sites. To better understand how VirA senses these inducers, the C58 virA gene was randomly mutagenized, and 14 mutants defective in vir gene induction and containing mutations which mapped to the input domain of VirA were isolated. Six mutants had single missense mutatiions in three widely separated areas of the periplasmic domain. Eight mutants had mutations in or near an amphipathic helix, TM1, or TM2. Four of the mutations in the periplasmic domain, when introduced into the corresponding A6 virA sequence, caused a specific defect in the vir gene response to glucose. This suggests that most of the periplasmic domain is required for the interaction with, or response to, ChvE. Three of the mutations from outside the periplasmic domain, one from each transmembrane domain and one from the amphiphathic helix, were made in A6 virA. These mutants were defective in the vir gene response to AS. These mutations did not affect the stability or topology of VirA or prevent dimerization; therefore, they may interfere with detection of AS or transmission of the signals to the kinase domain. Characterization of C58 chvE mutants revealed that, unlike A6 VirA, C58 VirA requires ChvE for activation of the vir genes.

p53 mutations in hepatocellular carcinoma related to oral contraceptive use

Oral contraceptives (OCs) are implicated in the development of hepatocellular carcinoma (HCC). Mitogenic stimulation may be the primary mechanism of tumorigenesis, but other factors may also contribute. Mutational spectrum analysis can provide insights into pathogenesis, therefore we analyzed the p53 tumor suppressor gene in 10 HCCs from women with a history of OC use. All were non-Asians whose average OC use was 6.7 years (range 2 months-13 years) and whose mean age at HCC diagnosis was 48.8 years (range 21-67 years). Each tumor was analyzed by immunohistochemistry, DNA sequencing and allelic deletion analysis. Three tumors were positive by p53 immunohistochemistry; allelic deletion analysis identified loss of heterozygosity in one of four informative cases. Two p53 point mutations were found in one tumor containing moderately and well-differentiated components; this patient was negative for all serological markers of hepatitis B and C infections. Both components showed p53 protein accumulation and a GTTval-->GCTala mutation at codon 274. In addition, a silent mutation (ACCthr-->ACTthr) at codon 140 of the p53 gene was detected in the moderately differentiated component of the tumor. These preliminary data indicate that p53 mutations are uncommon in OC-related HCCs. One of the two detected mutations was a G:C-->A:T transition at a non-CpG site, which is characteristic of DNA damage by free radicals. These data support a model whereby estrogens contribute to HCC development primarily through mitogen stimulation and secondarily by mutagenesis via hydroxyl radicals produced during estrogen metabolism. Confirmational analysis of a larger series is warranted.

Genetic susceptibility to cancer from exogenous and endogenous exposures

The past four decades of epidemiological research have yielded valuable information on the risks of populations to environmental exposures such as tobacco, asbestos, and dietary components. Prevention efforts have been focused on large-scale population-based interventions to minimize exposure to such external carcinogens. While some cancers are beginning to show a decline from changing environmental exposures, hormone-related cancers, such as breast and prostate, are becoming more prevalent. The development of these cancers appears to be closely related to endogenous exposures to circulating steroid hormones. Although prevention trials using antihormone agents are proving successful in some instances, the long-term control of these cancers necessitates a clearer understanding of the metabolism and transport of the relevant hormone in vivo. The revolution in molecular biology has provided powerful genetic tools for evaluating mechanisms of cancer causation as well as the potential to better define individual susceptibility. Using tobacco exposure as an example, we and others have demonstrated that polymorphisms in genes controlling aromatic amine metabolism provide at least a partial explanation for ethnic and individual susceptibility to bladder cancer. Similar studies have examined genetic polymorphisms in the metabolism of tobacco smoke and lung cancer risk, red meat and colorectal cancer, and aflatoxin and liver cancer. Our current studies have pursued a similar paradigm of genetic polymorphism and individual cancer susceptibility in prostate and breast carcinogenesis. We are evaluating polymorphisms in the steroid 5 alpha-reductase type II and androgen receptor genes in relation to prostate cancer based on the evidence that intracellular dihydrotestosterone is the critical "carcinogen." We are pursuing genetic polymorphisms affecting estradiol metabolism, including those in the 17 beta-hydroxysteroid dehydrogenase 2 and estrogen receptor genes as they relate to susceptibility to breast cancer. The potential role of a polymorphism in the cytochrome P450c 17 alpha gene in both breast and prostate cancers is also being examined.

Treatment of multidrug-resistant tuberculosis in Taiwan

Eighty-seven patients with multidrug-resistant tuberculosis (MDR-TB) diagnosed between 1988 and 1990 were treated with isoniazid and at least three other effective second-line drugs based on in vitro susceptibility tests. Of these patients, 10% failed to adhere to the regimen and 43% remained sputum positive after 6 months of treatment. Only 47% showed sputum conversion within 6 months of treatment and 12% of them relapsed during the first year of follow-up. From September 1987 to July 1989, 36 patients with MDR-TB were treated with a regimen containing rifabutin, isoniazid and at least three other susceptible drugs. Only 47% achieved a sustained sputum conversion. Four died during treatment due to disease progression. From March 1992 to July 1993, 17 cases of MDR-TB were treated with an ofloxacin-containing anti-TB regimen for 12-24 months. Two failed to adhere to the regimen for more than 1 month during the first 6 months of therapy. Among the remaining 15, 26% failed to achieve sputum conversion, 73% achieved bacterial conversion, 9 within 1 month and the other 2 within 2 months. No significant adverse effect was associated with ofloxacin use. We concluded that ofloxacin is a better choice among the more toxic and less potent second-line drugs, and should be used along with other anti-TB drugs in treating patients with MDR-TB.

Immunohistochemical studies of GABA and parvalbumin in the developing human cerebellum

The localization of GABA and parvalbumin was studied in the developing cerebellum of human fetuses from 16 to 28 weeks of gestation. The avidin-biotin complex immunohistochemical method combined with silver staining were used to reveal the presence of GABA- and parvalbumin-positive neurons and nerve fibres. As early as the 16th week of gestation, GABA immunopositivity was observed in the cerebellar cortex and the deep nuclei. GABA-positive neurons included Purkinje cells, stellate and basket cells of the cerebellar cortex and neurons in the deep nuclei. The gradient of immunoreactivity increased with the maturing cells, being weak at 16 weeks and becoming markedly pronounced at 28 weeks of gestation. GABA-immunopositive mossy fibres were observed in the granular cell layer at 16 weeks, and by 28 weeks, a robust fibre network was present in the cortex and deep nuclei. Immunohistochemical localization for parvalbumin indicates that weak immunoreactivity was observed in Purkinje cells, stellate and basket cells at 16 weeks of gestation, increasing in intensity with advancing age, notably in the Purkinje cells which had acquired an elaborate arbor of neurites at 28 weeks of gestation. In the deep nuclei, parvalbumin-positive cells and nerve fibres were observed throughout the 16 to 28 week period. These results indicate that GABA- and parvalbumin-positive neurons and fibres appeared as early as 16 weeks of gestation, expressing a high degree of immunoreactivity by the 28 week of fetal age.

Glutathione S-transferase M1 genotype affects aminobiphenyl-hemoglobin adduct levels in white, black and Asian smokers and nonsmokers

Cigarette smoking is the major cause of bladder cancer in men in the United States, and the arylamines contained in cigarettes smoke, including 4-amino-biphenyl (4-ABP), are believed to play an important role in the induction of bladder cancer among smokers. N-acetylation, which is catalyzed by the genetically controlled hepatic N-acetyltransferase enzyme displaying two phenotypes (slow versus rapid), is a detoxification pathway for arylamines with regard to bladder carcinogenesis. In Los Angeles, CA, non-Hispanic white (white), black, and Asian males have comparable smoking habits and yet dramatically different risks of bladder cancer (31 of 100,000 in whites, 16 of 100,000 in blacks, and 13 of 100,000 in Chinese and Japanese). Previously, we have demonstrated that the prevalence of slow acetylators (the high-risk phenotype) was highest in whites (54%), intermediate in blacks (34%), and lowest in Asians (14%). We also showed that mean 3- and 4-ABP hemoglobin adduct levels were significantly higher in cigarette smokers relative to nonsmokers, and that the level increased with increasing number of cigarettes smoke/day. Most importantly, slow acetylators consistently exhibited higher mean levels of ABP hemoglobin adducts relative to rapid acetylators, regardless of race and level of cigarette smoking. We assessed 151 residents of Los Angeles County (CA) who were either white, black, or Asian (Chinese or Japanese) and over the age of 30 years for their glutathione S-transferase M1 (GSTM1) genotype (null versus non-null), acetylator phenotype (slow versus rapid), levels of 3- and 4-ABP hemoglobin adducts, and current use of tobacco products. Whites (27%) had the highest prevalence of the highest risk profile (slow acetylator, GSTM1 null), followed by blacks (15%) and Asians (2.7%), and the difference was statistically significant (P = 0.006). Whites also had less than one-half the prevalence of the "protective" profile (rapid acetylator, GSTM1 non-null) relative to blacks and Asians (23 versus 57%; P = 0.0001). Regardless of race and level of cigarette smoking, mean levels of 3- and 4-ABP hemoglobin adducts were higher in subjects possessing the higher risk (GSTM1/acetylator profile. Mean level of 4-ABP hemoglobin adduct (adjusting for race, cigarette smoking, and acetylator phenotype) was significantly higher in subjects possessing the GSTM1-null versus GSTM1-non-null genotype (46.5 versus 36.0 pg/g Hb; P = 0.037). The comparable difference in mean levels of 3-ABP hemoglobin adduct was borderline significant (1.6 versus 1.1 pg/g Hb; P = 0.07). Thus, our results suggest that GSTM1 is involved in the detoxification of 3- and 4-ABP and may contribute to the racial variation in bladder cancer incidence among white, black, and Asian males in Los Angeles, CA.

[Disseminated Strongyloides stercoralis infection mimicking pneumonia]

Strongyloides stercoralis is an intestinal nematode. In an immunocompetent host, Strongyloides infections usually produce only mild gastrointestinal symptoms. However, in an immunocompromised host, widespread dissemination of larvae to the extra-intestinal organs may occur. If unrecognized, the mortality rate is high. Here we report a case of disseminated strongyloidiasis in a chronic obstructive pulmonary disease (COPD) subject whose chest radiograph demonstrated multiple pneumonic patches and interstitial infiltrates. Strongyloides larvae were found in stool, sputum, and urine, and embryonated eggs were also found in sputum. The patient was treated successfully with mebendazole and alben albendazole. In conclusion, although high mortality rate is noted in disseminated strongyloidiasis, it is still a curable disease when early diagnosis and treatment could be made.

A urinary marker of alcohol intake

Previously, one of us (B. K. T.) developed an assay that measures levels of free ethanol and ethanol conjugates in urine and showed that the mean levels of these ethanol markers in confirmed alcoholics were at least 20-fold higher than those levels in control subjects. In this study, we assessed the relationship of these biomarkers with self-reported levels of alcohol intake in a multiethnic sample of Los Angeles County residents who were male and over the age of 35 years (n = 128; 40 non-Hispanic whites, 46 blacks, 17 Chinese, and 25 Japanese). Regardless of race, the mean levels of free, bound, and total (free plus bound) ethanol were lowest in nondrinkers, intermediate in weekly drinkers, and highest in daily drinkers (P = 0.0001 in all three statistical tests of differences in the three biomarkers). Stepwise discriminant analysis showed that of the three potential biomarkers, total ethanol best discriminates between the three classes of drinkers (non, weekly, and daily), and that additional inclusion of either free or bound ethanol in the discriminant function had negligible effect. Overall, mean level of total ethanol was 2.2 times higher in weekly than in nondrinkers; daily drinkers, in turn, showed a 4.2-fold increase in mean total ethanol relative to weekly drinkers. However, there was no correlation between any of the three biomarkers and self-reported level (in grams of ethanol) of average consumption in either weekly or daily drinkers whose mean intake was about 13 and 42 g of ethanol/day, respectively. As the level of urinary free ethanol and ethanol conjugates showed extraordinary differences among racial groups for a given level of self-reported ethanol intake, the data suggest possible interracial differences in the in vivo elimination rate of ethanol; this latter finding needs to be confirmed in larger studies.

A cohort study of serum testosterone and hepatocellular carcinoma in Shanghai, China

A nested case-control study of HCC based on a cohort of 18,244 middle-aged men in Shanghai, China, who had been followed for an average of 5.3 years, was conducted. Our hypothesis dealt with the possible role of testosterone in the etiology of HCC, which shows a minimum of a 2- to 3-fold male excess in all populations world-wide. Seventy-six incident cases of HCC and 410 control subjects drawn from the cohort and individually matched to the cases by age (within 1 year), time of blood sample collection (within 1 month) and neighborhood of residence were assessed for serum HBsAg, anti-HBc, anti-HBs, anti-HCV and testosterone. Among controls, serum testosterone levels were similar between those who had no markers of HBV infection, those who were positive for anti-HBs only and those who were positive for anti-HBc but negative for HBsAg. However, the geometric mean level of testosterone in HBsAg-positive controls was 21% higher relative to HBsAg-negative controls and the difference was statistically significant (2-sided p = 0.0006). Relative to controls, HCC cases had a significantly higher mean level of testosterone at the time of recruitment (570 vs. 485 ng/dl, 2-sided p = 0.0005), but the difference was explicable on the basis of a higher proportion of HBsAg-positive individuals among cases than controls (p = 0.42 after adjustment for HBsAg status).