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Biomedical subjects

N Muñoz

Publications and source records attributed to N Muñoz.

At least 145 records · Page 8Linked to original sources
PubMed1989

Patterns of familial transmission of HBV and the risk of developing liver cancer: a case-control study in the Philippines.

The present case-control study was carried out in the Philippines to determine the risk of developing hepatocellular carcinoma (HCC) in relation to different HBV serological profiles of parents and sibs of HCC cases and controls. The HBV serological profiles of parents and sibs of 33 patients with HCC were compared with those of 2 types of community control: 33 general population controls matched for sex and age (C1 controls) and 33 asymptomatic HBsAg carriers also matched for sex and age (C2 controls). When cases were compared with C1 controls, increased risks were associated with the fact of having an HBsAg-positive mother (RR = 2.5, 95% C1 = 0.4-26.3) and older sibs positive for HBsAg (RR = 2.0, 95% C1 = 0.5-9.1), but the increased risk was not statistically significant. However, a significantly increased risk was associated with the fact of having a mother (95% C1 = 3.5-infinity) or father (RR = 11, 95% C1 = 1.6-473) who had been exposed to HBV. On the other hand, when cases were compared with C2 controls, a non-significant 2-fold increase was associated with the fact of having an HBsAg-positive mother, but no differences were observed in the HBV serological profiles of their fathers and older sibs. These results suggest that, in the Philippines, the fact of having a mother or father who has been infected in the past with HBV increases the risk of developing HCC but that the contribution of the mother to this increase in risk is not as important as hitherto believed.

Female↗
PubMed1989

Precursor lesions of oesophageal cancer in young people in a high-risk population in China.

Young people (15-26 years) were selected from households in a population in China at high risk of oesophageal cancer on the basis of whether a case of oesophageal cancer had (166 participants) or had not (372 participants) occurred in a first-degree relative. In an endoscopic survey 43.5% of the male subjects and 35.9% of the female subjects showed histological signs of chronic oesophagitis. The presence of these precursor lesions was significantly associated in a multivariate logistic model with consumption of burning hot beverages, a family history of oesophageal cancer (including second-degree relatives), infrequent consumption of fresh fruit, and infrequent consumption of dietary staples other than maize.

Adolescent↗
PubMed1988

Blood, retinol and zinc riboflavin status in relation to precancerous lesions of the esophagus: findings from a vitamin intervention trial in the People's Republic of China.

Data from a double-blind intervention trial in China are reanalyzed to explore auxiliary information. The trial had shown that in a high-risk area for esophageal cancer the dietary supplementation of apparently healthy individuals with a combination of retinol, riboflavin, and zinc did not lead to a different prevalence of precancerous lesions of the esophagus among those receiving the active treatment compared to a placebo group. However, improvement of blood retinol and zinc levels were also observed in the placebo group. The logistic regression analysis presented in this paper illustrates that those individuals who showed large increases in retinol, riboflavin, and zinc blood levels were more likely to have a histologically normal esophagus at the end of the trial. This effect is clearer for retinol than for riboflavin and zinc and it is independent of whether the change was caused by the active treatment or occurred otherwise.

Adult↗
PubMed1988

Does human papillomavirus cause cervical cancer? The state of the epidemiological evidence.

The human papillomavirus has emerged over the past decade as the leading candidate to be the sexually transmitted aetiological factor in cervical cancer. Although it appears that papillomavirus types 16 and 18 are associated with a higher risk of advanced cervical neoplasia, most of the evidence comes from studies which do not satisfy basic epidemiological requirements, and are therefore difficult to interpret. The most significant problems are the small sample size, potentially biased selection of study subjects, the difficulties in cytologically distinguishing precancerous lesions from papilloma infection of the cervix, the unknown specificity and sensitivity of the various hybridisation methods for determining papillomavirus infection status, and the statistical analyses and presentation of results. On the basis of the existing studies, one is forced to conclude that, while experimental data suggest an oncogenic potential for HPV, the epidemiological evidence implicating it as a cause of cervical neoplasia is still rather limited.

DNA, Viral↗
PubMed1988

Prospects for epidemiological studies on hepatocellular cancer as a model for assessing viral and chemical interactions.

Chronic infection with hepatitis B virus (HBV) accounts for 1-10% of hepatocellular carcinoma (HCC) in low-risk countries and for 56-94% in high-risk populations. However, although HBV is perhaps the second most important human carcinogen so far identified, chronic HBV infection is neither a sufficient nor a necessary cause of HCC. Other factors must be causally related to HCC, and some of them have been identified: aflatoxins, tobacco smoking, and use of alcohol and oral contraceptives. The evidence for an association between these factors and HCC is reviewed, as well as their joint effects. Finally, prospects for epidemiological research on HCC, and specifically the assessment of viral and chemical interactions, are discussed.

Aflatoxins↗
PubMed1987

Tobacco smoking, occupational exposure and bladder cancer in Argentina.

The highest rate for bladder cancer in Latin America has been reported from La Plata, Argentina. A case-control study was carried out to investigate the reasons for this high rate. A total of 117 cases, 117 hospital controls and 117 neighbourhood sex- and age-matched controls were interviewed regarding their smoking and drinking habits and occupational exposures. Cigarette smoking and coffee drinking were identified as the major risk factors, and a significant association was also found for truck and railway drivers and for oil refinery workers. The relative risks for male smokers who ever smoked cigarettes vs. non-smokers was 4.3 (95% Cl: 1.9-10.3). The risk associated with black tobacco cigarettes was 2-3 times higher than that of blond cigarettes. For male ex-smokers the risk after 5 years of no smoking is less than one third of that of current smokers. The RR for drinking coffee was 2.4 (95% Cl: 1.4-4.4) after adjusting for the effects of tobacco smoking, and the risk increased with the number of cups per day. No association was found with the use of saccharin.

Age Factors↗
PubMed1987

Hot maté drinking and precancerous lesions of the oesophagus: an endoscopic survey in southern Brazil.

Thermal injury resulting from drinking very hot beverages has been incriminated as a risk factor for oesophageal cancer, although no information is available on the lesions caused by this injury in human or experimental animals. The drinking of hot maté tea is very common in areas of moderately high incidence of oesophageal cancer in south-eastern areas of South America. This study investigated the prevalence of precancerous lesions of the oesophagus in 60 unskilled male workers, of whom half were daily maté drinkers and the remainder were non-maté drinkers. These 2 groups were matched for age, smoking and alcohol intake. Maté drinkers were 2.2 times more likely (p = 0.046) to develop histologically confirmed oesophagitis than non-maté drinkers.

Adult↗
PubMed1987

Hot beverages and oesophageal cancer in southern Brazil: a case-control study.

There is a cluster of high-incidence areas of oesophageal cancer in south-eastern South America, including Southern Brazil, Uruguay and parts of Argentina. The present case-control study investigated the hypothesis that this may be due to the drinking of maté, a traditional beverage drunk at a very high temperature, and also studied the role of other known risk factors such as alcohol and tobacco. Cases (171) and age- and sex-matched controls (342) were recruited from hospitals in the State of Rio Grande do Sul in Southern Brazil. The crude odds ratio for daily maté drinkers was 1.92 relative to those drinking less frequently than daily (p = 0.006). Other risk factors included the drinking of cachaça (a sugar cane spirit), smoking, rural residence, low fruit consumption and high intake of meats. After adjustment for these variables through conditional logistic regression, the odds ratio associated with daily maté drinking was reduced to 1.47 (90% CI = 0.87-2.50). Although the study failed to provide evidence of a strong association between maté and oesophageal cancer, the cluster of high rates could be explained by relative risks of the magnitude observed. This is due to the fact that approximately 70% of adult males and 50% of females are daily drinkers. In addition, this study revealed that alcohol, tobacco smoking and rural residence are the main risk factors for oesophageal cancer in this population and the fruit consumption confers some degree of protection.

Alcohol Drinking↗
PubMed1987

Delta agent and the etiology of hepatocellular carcinoma.

Sera from 87 patients with hepatitis B surface antigen (HBsAg)-positive hepatocellular carcinoma (HCC) and from 29 HBsAg-positive hospital controls were tested for delta (delta) antigen with an immunoenzymatic procedure and for anti-delta antibody, hepatitis Be antigen (HBeAg) and antibody to HBeAg (anti-HBe) by radioimmunoassay. All the sera, from both the HCC cases and the control patients, were negative for delta-antigen. Among the HCC cases 9 were positive for serum anti-delta (10%) whereas among the controls none was positive for this antibody (p = 0.067); the anti-delta-positive cases were found only among HCC patients negative for HBeAg. The lower prevalence of anti-delta among HBsAg-positive HCC patients, as compared to the corresponding prevalence among HBsAg-positive patients with chronic active hepatitis or cirrhosis (reported in the literature) indicates that the pathogenesis of HCC is frequently independent of the pathogenesis of the other HBsAg-positive common chronic liver diseases. By contrast, the higher prevalence of anti-delta among HBsAg-positive HCC cases than among HBsAg-positive controls may reflect the longer average duration of the carrier state in HCC patients (until integration is accomplished and the induction period completed). Serum HBeAg was higher among HBsAg-positive HCC patients with cirrhosis (23%) than among HBsAg-positive HCC patients without cirrhosis (6%) or HBsAg-positive controls (3%); thus, the conflicting results in the literature concerning the association of the HBeAg/anti-HBe system with HCC may be accounted for, in part, by the variable association of HCC with an underlying cirrhosis.

Carcinoma, Hepatocellular↗
PubMed1987

Hepatitis B virus, tobacco smoking and ethanol consumption in the etiology of hepatocellular carcinoma.

Tobacco smoking and alcohol drinking histories were obtained from 194 patients with hepatocellular carcinoma (HCC) and 456 hospital controls, and the results were analysed in conjunction with the results of serological determinations of hepatitis B surface antigen (HBsAg), antibody to HBsAg (anti-HBs) and antibody to hepatitis B core antigen (anti-HBc) in all subjects, as well as the presence or absence of cirrhosis in HCC patients. The relative risk (RR) of HCC (and 95% confidence interval) among HBsAg-positive subjects was 13.7 (8.0-23.5), whereas the excess risk among antibody-positive subjects was small and statistically non-significant. In the presence of cirrhosis the RR for HBsAg-positive subjects was considerably higher (30.7 vs. 7.1 among HBsAg-positive subjects without cirrhosis) indicating that HBV may affect the development of HCC through at least two different and potentially multiplicative mechanisms (DNA integration and liver regeneration). Moderate ethanol consumption does not affect the risk of HCC, but there is a statistically significant and dose-dependent association between tobacco smoking and HBsAg-negative HCC. In most of the developed countries of Europe and North America, where the prevalence of HBsAg carrier state is very low and tobacco smoking very common, more cases of HCC may be due to tobacco smoking than to HBV, even though the RR for HCC is much higher among HBsAg carriers than among tobacco smokers.

Adult↗
PubMed1987

Effect of riboflavin, retinol, and zinc on micronuclei of buccal mucosa and of esophagus: a randomized double-blind intervention study in China.

A randomized double-blind intervention trial was done in Huixian, People's Republic of China, a population with a high incidence of esophageal cancer. The aim of the trial was to determine whether a once-a-week treatment with retinol (15 mg or 50,000 IU), riboflavin (200 mg), and zinc (50 mg) could result, after 1 year, in a lower prevalence of precancerous lesions of the esophagus in the group receiving the active treatment as compared with the prevalence in the group receiving a placebo. The results of the trial, published elsewhere, indicated that the treatment had no effect on the prevalence of precancerous lesions of the esophagus. In determining whether an effect could be detected when earlier end points are used, the prevalence of micronuclei was evaluated in exfoliated cells from the esophagus and from the buccal mucosa in the present study. In a subsample of 200 out of the original 610 study subjects, smears were taken from the buccal mucosa before and after treatment, and in 170 subjects esophageal smears were obtained during endoscopy only after treatment. The smears were fixed and kept at room temperature over 1 year before being evaluated for the presence of micronuclei by means of 4'-6-diamidino-2-phenylindole fluorescent staining. Smears from approximately half of the subjects were considered suitable for evaluation. No statistically significant difference in the prevalence of micronuclei in the buccal mucosa cells was observed before and after treatment (the mean percentage of micronucleated cells in the vitamin group upon first examination, before treatment started, 0.35%; 1 year after treatment, 0.31%) or between the treatment and the placebo group at the final examination. (The mean percentage of micronucleated cells in the vitamin-treated group was 0.31 and 0.39% in the placebo group.) However, a statistically significant reduction (P = .04) was observed in the prevalence of micronuclei in esophageal cells in the treatment group as compared to the placebo. (The mean percentage of micronucleated cells in the vitamin-treated group was 0.19%; it was 0.31% in the placebo group.

Adult↗
PubMed1987

Intragastric nitrosation and precancerous lesions of the gastrointestinal tract: testing of an etiological hypothesis.

The N-nitrosoproline (NPRO) test was used to study whether subjects with precancerous conditions of the stomach have an elevated potential for endogenous nitrosation. The highest yield of NPRO after ingestion of beetroot juice (as a source of nitrate) and proline was seen in subjects whose pH of fasting gastric juice was about 1.5-2. No increased level of NPRO was detected in subjects with more advanced lesions, compared to those with a normal stomach. Counts of total and nitrate-reducing bacteria were positively correlated with the pH of gastric juice but did not correlate with the urinary level of NPRO in the same individuals. Bacteria and intragastric nitrosation are discussed as possible etiological factors in human stomach cancer.

Adult↗
PubMed1986

Vitamin measurements in pooled blood samples.

From 610 blood samples collected in September 1983 in an intervention trial in Huixian, Henan Province, People's Republic of China, which were individually analyzed for retinol, beta-carotene, and alpha-tocopherol levels, 10 pools were formed from 50 individual samples, and the vitamin levels in the merged pools were also measured. Oxidation losses by repeated thawing and refreezing render the absolute levels measured in the pools smaller than the corresponding means of the individual measurements. A very good relative agreement was found between pool levels of retinol and beta-carotene and the respective means. The pooling technique could be a valuable tool in large correlation studies and has possible further applications in case-control studies.

Adult↗
PubMed1985

Proliferative abnormalities of the oesophageal epithelium of Chinese populations at high and low risk for oesophageal cancer.

Studies on the pattern of proliferation of epithelial cells from the oesophagus of 33 individuals from Linxian, a high-risk area for oesophageal cancer in China, and of 22 subjects from Jiaoxian, a low-risk area for the same cancer in China, were performed using thymidine labelling. Oesophageal biopsies were obtained during endoscopic surveys carried out in these 2 populations. A clear difference was observed between the 2 groups; the high-risk group showed cell proliferation in the upper layers of the epithelium more often than the low-risk group. No difference was found in the cell proliferation patterns of subjects with oesophagitis and those without oesophagitis in the high-risk area. This finding could suggest that the tritiated thymidine assay may be a more sensitive method to characterize the precancerous lesions of the oesophagus in high- and low-risk populations than simple histological evaluation.

Adult↗