PubMed Health⌕ Search

Biomedical subjects

N Muñoz

Publications and source records attributed to N Muñoz.

197 records · Page 11Linked to original sources
PubMedDate not supplied

Epidemiology and molecular pathology of gallbladder cancer.

Gallbladder cancer is usually associated with gallstone disease, late diagnosis, unsatisfactory treatment, and poor prognosis. We report here the worldwide geographical distribution of gallbladder cancer, review the main etiologic hypotheses, and provide some comments on perspectives for prevention. The highest incidence rate of gallbladder cancer is found among populations of the Andean area, North American Indians, and Mexican Americans. Gallbladder cancer is up to three times higher among women than men in all populations. The highest incidence rates in Europe are found in Poland, the Czech Republic, and Slovakia. Incidence rates in other regions of the world are relatively low. The highest mortality rates are also reported from South America, 3.5-15.5 per 100,000 among Chilean Mapuche Indians, Bolivians, and Chilean Hispanics. Intermediate rates, 3.7 to 9.1 per 100,000, are reported from Peru, Ecuador, Colombia, and Brazil. Mortality rates are low in North America, with the exception of high rates among American Indians in New Mexico (11.3 per 100,000) and among Mexican Americans. The main associated risk factors identified so far include cholelithiasis (especially untreated chronic symptomatic gallstones), obesity, reproductive factors, chronic infections of the gallbladder, and environmental exposure to specific chemicals. These suspected factors likely represent promoters of carcinogenesis. The main limitations of epidemiologic studies on gallbladder cancer are the small sample sizes and specific problems in quantifying exposure to putative risk factors. The natural history of gallbladder disease should be characterized to support the allocation of more resources for early treatment of symptomatic gallbladder disease in high-risk populations. Secondary prevention of gallbladder cancer could be effective if supported by cost-effective studies of prophylactic cholecystectomy among asymptomatic gallstone patients in high-risk areas.

Cholelithiasis↗
PubMedDate not supplied

Antibodies to Helicobacter pylori and pepsinogen levels in children from Costa Rica: comparison of two areas with different risks for stomach cancer.

In children and adolescents from two areas of Costa Rica with contrasting gastric cancer risks, two factors suspected to be linked to the natural history of the disease were tested: serum antibodies to Helicobacter pylori and serum pepsinogen levels. One hundred fifty-five subjects from the high-risk area of Turrubares were compared to 127 from the low-risk area of Hojancha. No significant differences were found in the prevalence of IgG or IgA antibodies to Helicobacter pylori between the two regions. The prevalence of IgG was 65.8% in the high-risk area and 72.4 in the low-risk area, and that of IgA was 43% in both areas. The levels of pepsinogen, especially pepsinogen C, were significantly elevated in subjects with H. pylori antibodies in their serum. The mean levels of pepsinogen C in those negative, positive, and strong positive for H. pylori antibodies were 8.7, 14.3, and 21.1 ng/ml. These findings suggest that H. pylori-associated gastritis, predominantly of antral localization, is very prevalent in Costa Rican children and adolescents. Such gastritis might be associated with a high prevalence of intestinal metaplasia and a high gastric cancer risk in the inland, but not the coastal rural populations. H. pylori may therefore be an insufficient cause whose role in gastric carcinogenesis is contingent upon the presence of other factors.

Adolescent↗
PubMedDate not supplied

Micronuclei in esophageal cells of Chinese youths in a high-incidence area for esophageal cancer in China.

An epidemiologic survey among 538 young persons between 15 and 26 years of age in a high-risk area for esophageal cancer in the People's Republic of China revealed a high prevalence of esophagitis. Histologically confirmed very mild, mild, and moderate esophagitis was observed in 31.6%, 10.7%, and 1.1% of 354 male and 30.4%, 4.3%, and 1.1% of 184 female subjects. The prevalence of micronuclei in esophageal smears was assayed in a subsample to investigate its possible association with esophagitis and with risk factors for esophageal lesions. Of the 186 subjects, 2.7% had mild or moderate esophagitis, 19.9% had very mild esophagitis, and 77.4% were normal. The frequency distribution of micronucleated cells in the esophageal mucosa was similar for the three diagnostic groups. Mean percentages of micronucleated cells did not differ by diagnosis of esophagitis, household status, current smoking status, presence of oral leukoplakia, or consumption of burning hot beverages or fresh fruit. Higher mean percentages were observed in the older age group of both sexes, but the difference was not statistically significant. The results suggest that if esophagitis is considered an important precursor state in the development of esophageal cancer, the scoring of micronuclei does not appear to be an efficient test for mild forms of esophagitis.

Adolescent↗
PubMedDate not supplied

[Enteroparasitoses in the V Region, Chile. A study of rural school children from Santo Domingo, 1987].

The results of a new enteroparasitological survey carried out by the authors are analyzed with the aim of contributing to the knowledge of the situation of these infections in the V Region, Chile. In 1987 the children of five rural schools of Santo Domingo were studied by means of the modified Telemann method, the Ziehl-Neelsen stain and seried Graham test. The parasites more frequently found were: E. vermicularis (50.4%) and G. lamblia (10.8%). No E. histolytica was found in these children. The most frequent commensal was E. nana (21.9%). Cryptosporidium sp. presented a low frequency (0.9%), a figure that in these asymptomatic subjects is in accordance with that found in outpatients with chronic diarrhea in Valparaíso, V Region.

Adolescent↗
PubMedDate not supplied

[Enteroparasitoses in children from the V Region. A study in the Juan Fernandez archipelago, Chile].

The results of two enteroparasitological surveys in children carried out in the Juan Fernandez Archipelago, within a 5-year period (1982-1987), are compared. In both studies the absence of Ascaris lumbricoides has been persistent, having no explanation for this phenomenon due to the favorable environmental conditions for the development of the quoted parasite. In the second survey Cryptosporidium sp. was studied, finding a higher frequency than that detected in rural areas of the V Region.

Child↗
PubMedDate not supplied

[Intestinal parasites and ectoparasites in the V region, Chile: study in the Psychiatric Hospital of Putaendo].

A prospective study was carried out in 229 chronic patients (of both sexes) from the Psychiatric Hospital of Putaendo, in order to find out the frequency of intestinal parasites and/or commensals in the period 1987-1989. One hundred and ninety four (84.7%) out of the 229 studied patients were infected by parasites and/or commensals. The high prevalence of commensals Entamoeba coli (55.0%) and Endolimax nana (50.5%) became more evident. Among the parasites, the most frequent was Trichuris trichiura (41.5%). The presence of Pediculus humanus capitis and lesions suggestive of those produced by Sarcoptes scabiei were detected in 7.2 and 0.6 of the examined patients. The results obtained show the high frequency of intestinal infections by parasites and commensals in the patients of the studied hospital.

Adolescent↗
PubMedDate not supplied

Risk factors for progression of cervical intraepithelial neoplasm grade III to invasive cervical cancer.

Data from four case-control studies on invasive cervical cancer and on cervical intraepithelial neoplasia grade III (CIN III) that were concurrently conducted in Spain and Colombia were used to look for factors that might favor the progression from CIN III to the invasive stage. These studies were compared in two ways; a case-case comparison and an estimation of the ratio of odds ratios with the use of of special logistic regression model that took into account the different design of each study and possible confounding factors. Variables studied were human papillomavirus status, viral load, viral types, sexual behavior, sexually transmitted diseases, reproductive patterns, oral contraceptives, and smoking. Both CIN III and invasive cervical cancer have a very similar profile of risk factors and none of them was different in a consistent way to suggest a role in the progression from CIN III to invasive cervical cancer. Some methodological problems such as cohort-specific differences and some selection biases could be adjusted for with a careful statistical analysis. Other problems derived from the cross-sectional nature of the design are unavoidable and should be considered in the interpretation of the results.

Adult↗
PubMedDate not supplied

Alcohol, tobacco, diet, mate drinking, and esophageal cancer in Argentina.

To study the role of hot mate drinking, alcohol, tobacco, and diet in esophageal cancer, a case-control study including 131 cases and 262 hospital controls was carried out in La Plata, Argentina. In multivariate analyses, statistically significant increases in risk were detected for alcohol, tobacco, and some dietary factors but not for hot mate drinking. A strong dose-response relationship was observed with the amount of alcohol consumed daily but not with the number of cigarettes smoked. The odds ratio for those drinking more than 200 ml of ethanol/day compared to nondrinkers was 5.7 (95% confidence interval, 2.2-15.2). An increased risk was also observed for those eating barbecued meat more than once a week (odds ratio, 2.4; 95% confidence interval, 1.2-4.8) as compared to those eating it less than once a week, and a reduction in risk was associated with daily consumption of nonbarbecued beef as compared to those eating it less than daily. Concerning mate drinking, the only variable that showed an effect was the temperature at which mate is drunk. Those who reported drinking mate hot or very hot as compared to those drinking it warm had an increase in risk (odds ratio, 1.7; 95% confidence interval, 1.0-2.9). Our findings strengthen the evidence for an important role of alcohol and tobacco in esophageal carcinogenesis but do not provide strong support for a role of hot mate drinking.

Aged↗
PubMedDate not supplied

Importance of human papillomavirus endemicity in the incidence of cervical cancer: an extension of the hypothesis on sexual behavior.

The risk of cervical cancer for a woman depends largely on the probability of being infected with some specific types of Human Papillomavirus (HPV). In the control groups of four case-control studies in Colombia and Spain we have shown a strong correlation between the number of sexual partners of males and females and HPV DNA prevalence in the genital tract. Our results suggest that the lifetime number of sexual partners in both sexes are surrogates of the probability of HPV infection and, as such, insufficiently explain the geographical variation in the incidence of cervical cancer. It is proposed that the high rates of cervical cancer in Latin America are linked to the largely unknown characteristics of the HPV endemicity in the population and to the absence of widespread screening for cervical neoplasia. Reliable surveys on the HPV prevalences in selected social groups (i.e., young males and prostitutes) as well as in populations in countries at different risk of cervical cancer are required.

Adult↗
PubMedDate not supplied

Is Helicobacter pylori a cause of gastric cancer? An appraisal of the seroepidemiological evidence.

The epidemiological evidence linking Helicobacter pylori infection to stomach cancer is reviewed here in ascending order of epidemiological strength. Only those studies in which exposure to H. pylori was assessed by serology are considered. Ecological studies or geographical correlation studies have revealed inconsistent results when the incidence or mortality rates of stomach cancer have been correlated with the prevalence rates of H. pylori infection. Only those studies with a wide range in gastric cancer rates and in which a large number of populations are compared show weak but significant positive correlations. However, it is well known that these studies are difficult to interpret and do not provide strong evidence for a causal association. In only those case-control studies carried out in low-risk countries for gastric cancer, an increased risk for stomach cancer has been found associated with the presence of H. pylori antibodies. In high-risk countries for gastric cancer the lack of association may be explained by the use of inappropriate serological assays. Three case-control studies nested within cohorts have consistently shown an increased risk among subjects in whom the presence of H. pylori antibodies have been detected many years before the cancer diagnosis. They constitute the strongest evidence for a causal association. The final proof of causality will be provided by intervention studies in which it is demonstrated that long-term eradication of H. pylori is followed by a reduction in the gastric cancer rates. However, our own experience has shown that such studies are not easy to implement.

Case-Control Studies↗
PubMedDate not supplied

Human papillomavirus and cervical intraepithelial neoplasia grade III/carcinoma in situ: a case-control study in Spain and Colombia.

A case-control study of 525 cases of cervical intraepithelial neoplasia grade III (CIN III) and 512 controls was conducted in Spain and Colombia between 1985 and 1988 to assess the role of human papillomavirus (HPV) in the etiology of CIN III. HPV DNA in cytological scrapes from the cervix was assessed by Virapap and by polymerase chain reaction (PCR) based on the L1 consensus primers. A subsample of 268 specimens was also tested for HPV DNA using Southern hybridization. In Spain, the PCR-based prevalences of HPV DNA were 70.7% among cases and 4.7% among controls. Odds ratio (OR) and 95% confidence interval (numbers in parentheses) for HPV DNA were 56.9 (24.8-130.6). In Columbia HPV DNA was detected by PCR in 63.2% of the cases and in 10.5% of the controls. The OR was 15.5 (8.2-29.4). The estimated fractions of CIN III attributable to HPV were 72.4% in Spain and 60.3% in Colombia. HPV 16 was the predominant viral type and showed the strongest association with CIN III; in Spain the OR was 295.5 (44.8-1946.4) and in Colombia the OR was 27.1 (10.6-69.5). HPV DNA of unknown type was frequent in HPV-positive cases (18.3% in Spain and 38.0% in Colombia) and controls (66.7% in Spain and 47.4% in Colombia). The comparison of results from Virapap and PCR indicated that PCR is the method of choice for epidemiological studies. These data strongly support the hypothesis of the viral origin of CIN III, the common etiology of CIN III and invasive cervical cancer, and the causal nature of the association between HPV and CIN III.

Adult↗
PubMedDate not supplied

Risk factors for cervical intraepithelial neoplasia grade III/carcinoma in situ in Spain and Colombia.

A case-control study of 525 histologically confirmed cases of cervical intraepithelial neoplasia grade III and 512 controls was done in Spain and Colombia to assess the role of various risk factors taking into account the effect of human papillomavirus (HPV). The presence of HPV DNA, assessed by a polymerase chain reaction-based method, was the strongest risk factor identified. In Spain the adjusted odds ratio (OR) and 95% confidence interval (CI) (numbers in parentheses) were 56.9 (24.8-130.6) and, in Colombia, were 15.5 (8.2-29.4). In addition to HPV, the multivariate analysis revealed independent effects of early age at first intercourse (in Spain ORa, 4.3; 95% CI, 2.0-9.3 for ages < 17 versus 20+ years and in Colombia ORa, 9.0; 95% CI, 2.6-30.9 for ages < 14 versus 20+ years), and antibodies to Chlamydia trachomatis (in Spain ORa, 2.3; 95% CI, 1.1-4.5; and in Colombia ORa, 1.7; 95% CI, 1.1-2.7). High parity showed a significant effect only in Colombia (ORa, 2.0; 95% CI, 1.0-5.0 for > or = 6 versus 1) while number of partners of the woman and specially of her husband showed a strong effect in Spain only (ORa, 6.9; 95% CI, 3.1-15.3 for partners of the husband > or = 21 versus 1-5). Smoking and use of oral contraceptives did not show significant or consistent associations. Among HPV-DNA positive women early age at first intercourse and high parity increased the risk of cervical intraepithelial neoplasia III but the effect was statistically significant only for the former.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Prostitution, HIV, and cervical neoplasia: a survey in Spain and Colombia.

The prevalence of cervical intraepithelial neoplasia (CIN) and the association of CIN with prostitution was examined in Oviedo, a region in Spain with low incidence of cervical cancer, and in Cali, Colombia, where the incidence of cervical cancer is 6-10 times higher. In Oviedo, the study included 758 prostitutes attending a sexually transmitted diseases clinic and 1203 nonprostitutes attending a family-planning clinic. In Cali, 775 prostitutes and 1795 nonprostitutes attending health centers were included. Seropositivity to common sexually transmitted agents was investigated in Spanish prostitutes. No significant difference was found in the prevalence of CIN between Oviedo and Cali in both prostitutes (2.5 versus 1.8%) and nonprostitutes (1.2 versus 1.1%). Prostitutes had a 2-fold increased risk of CIN as compared to nonprostitutes; in Spain, the prevalence odds ratio (POR) was 2.3 and the 95% confidence interval (CI) was 1.1-4.5, and, in Colombia, POR was 1.8 and the 95% CI was 0.9-3.5. Among prostitutes in Oviedo, human immunodeficiency virus (HIV) prevalence was 4.9% and HIV-positive prostitutes showed a high risk of CIN as compared to HIV-negative prostitutes (POR, 12.7; 95% CI, 3.9-40.9); 76% of HIV-positive prostitutes were i.v. drug users and showed an increased seroprevalence of other sexually transmitted diseases. HIV-negative prostitutes did not show any increased risk of CIN (POR, 1.2; 95% CI, 0.5-2.8). These results show that among nonprostitutes the prevalence of CIN was not statistically different between the two cities in Spain and Colombia; prostitutes were at moderate increased risk compared to nonprostitutes in both cities.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

In vivo nitrosoproline formation and other risk factors in Costa Rican children from high- and low-risk areas for gastric cancer.

The hypothesis that intragastric synthesis of N-nitroso compounds (NOC) in early life could play a role in gastric carcinogenesis was tested by applying the N-nitrosoproline (NPRO) test to about 50 children living in high- and low-risk areas for stomach cancer in Costa Rica. The median values of excretion of NPRO and the sum of three nitrosamino acids (micrograms/12 h urine) were 10-20% of those in adults from other geographical high-risk areas for stomach cancer. The urinary NPRO level after proline intake was higher in children from the high-risk area (P < 0.04) and markedly reduced after ingestion of ascorbic acid together with proline (P < 0.05). NPRO levels on the day of proline intake were highly correlated with levels of nitrate excretion (P < 0.001). Mean levels of total NOC in an aqueous (pH 2) extract of cooked beans from the high- and low-risk areas were similar. Acid-catalyzed nitrosation of the extract increased the total NOC concentration up to 1000-fold, but there was no difference between samples from the two areas. About 10% of bean extracts from both areas showed weak direct-acting genotoxicity in Escherichia coli; after acid-catalyzed nitrosation, all samples were genotoxic at similar levels. The diet of children in the low-risk area satisfied recommended levels of intake of energy and most nutrients except riboflavin and retinol equivalents. Diets from the high-risk area were deficient in energy intake and all nutrients except protein and vitamin C.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗