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Miquel Porta

Publications and source records attributed to Miquel Porta.

34 records · Page 2Linked to original sources
PubMed2002

Generalizing molecular results arising from incomplete biological samples: expected bias and unexpected findings.

PURPOSE: In molecular epidemiology, obtaining biological samples for all subjects targeted for study is frequently hampered by ethical, clinical, and logistic factors. The extent to which the incompleteness of biological samples could cause bias is rarely analyzed in depth. Here we report some expected bias and some unexpected findings during a study on mutations in the K-ras gene in exocrine pancreatic cancer (EPC). METHODS: In this case-case study, all patients registered with EPC between 1980 and 1990 at two general hospitals were retrospectively identified from the hospital tumor registries. Their clinical records were abstracted and paraffin-embedded samples retrieved from pathology records. DNA was amplified, and mutations in codon 12 of the K-ras gene were detected using the artificial RFLP technique. RESULTS: Results on the mutations (RM) were obtained for 51 of the 149 cases of EPC (34.2%). There were no significant differences on the availability of RM by age, gender, and tumor stage at diagnosis, but RM were over five times more likely to be available from one of the hospitals. Subjects with RM were more likely to have received a treatment with curative intent (OR = 11.56, 95% CL: 2.88-46.36). The existence of RM was positively associated with the availability of information on alcohol use and family history of cancer. Subjects with RM tended to belong to higher occupational groups and to smoke less than subjects without RM. Unexpectedly--given that in EPC K-ras mutations have consistently been found unrelated to age, gender, tumor stage, and other clinical factors-, cases with a K-ras mutation were more likely than wild-type cases to have information on tobacco and alcohol use (OR = 3.29, p = .21), medical history (OR = 4.46, p = .41), and family history of cancer (OR = 4.80, p = .01). The relationship between completeness of clinical records and K-ras mutations among cases with RM could not be accounted by age, gender, and occupational group. CONCLUSIONS: Simple tests of age and gender distributions among subjects with and without available clinical information and molecular results may not rule out selection and information bias. Studies using biologic specimens are even more in need than classic studies to explain clearly the process followed to include and exclude subjects. Additional caution is needed when generalizing molecular results arising from incomplete biological specimens.

Aged↗
PubMed2002

Symptom-to-diagnosis interval and survival in cancers of the digestive tract.

The objective was to identify the main correlates of the symptom-to-diagnosis interval (SDI) and to analyze their influence upon the survival in patients with cancers of the digestive tract. Two hundred forty-eight symptomatic patients with cancer of the esophagus (N = 31), stomach (N = 70), colon (N = 84), and rectum (N = 66) were interviewed and prospectively followed (median follow-up of 77 months). Cox's regression was used to assess the relative risk (RR) of death according to SDI. The median SDI was about 4 months, with nonsignificant differences by sex, age, social class, family history of cancer, or tumor site. The RR of death varied significantly by age (P = 0.012), tumor site (P < 0.01), tumor stage (P < 0.01), and type of hospital admission (P < 0.01). After adjustment for known and potential predictors of survival and as compared to an SDI < 2.5 months, the RR of death was 0.89 (95% CI: 0.61-1.32) for an SDI of 2.5-6 months, 0.78 (95% CI: 0.49-1.26) for SDI > 6-12 months, and 0.81 (95% CI: 0.44-1.49) for SDI > 12 months. These results do not imply that specific actions to hasten diagnosis must of necessity be ineffective, but underscore what a challenging task the secondary prevention of cancer remains.

Aged↗
PubMed2002

Occupational exposure to organic solvents and K-ras mutations in exocrine pancreatic cancer.

Occupational exposure to hydrocarbon solvents has been found to be associated with an increased risk of exocrine pancreatic cancer (EPC), the human tumor with the highest prevalence of K-ras mutations. Ras genes are critical DNA targets for chemical carcinogens. We analysed the relationship between past occupational exposure to hydrocarbon solvents and mutations in codon 12 of the K-ras gene in 107 incident cases of EPC. Information on occupational factors and life-style was obtained from personal interviews conducted during hospital stay. Occupational exposure to hydrocarbon solvents (aliphatic, aromatic, chlorinated, benzene, other organic solvents) was examined using two methods: expert assessment and the Finnish job-exposure matrix (Finjem). Exposure among K-ras mutated EPC cases (n = 83) was compared with that of K-ras wild-type EPC cases (n = 24). An association between K-ras mutations and solvent exposure was observed with Finjem but barely so with the expert assessment. Over 7-fold increased odds ratios (OR) were found for every group of solvents evaluated with Finjem (all P < 0.05). On the basis of the expert assessment, K-ras mutations were significantly associated only with exposure to benzene in men (OR = 7.07, P < 0.05). When requiring exposure to have occurred according to both the experts and Finjem, over 4-fold risks were obtained for aromatic, aliphatic, and for "any hydrocarbon solvent". A significantly higher proportion of cases with a mutation from glycine to valine (GGT-->GTT) or to aspartic acid (GGT-->GAT) were exposed to a hydrocarbon solvent. The results raise the possibility that hydrocarbon solvents might be involved in the pathogenesis of EPC, possibly through indirect modulation of K-ras activation. Since this is only the first study on occupational exposures and K-ras mutations in EPC, studies able to refute or to confirm the findings are required before public health implications, if any, are assessed.

Adult↗
PubMedDate not supplied

Is joint hypermobility related to anxiety in a nonclinical population also?

This study examines the association between joint hypermobility syndrome and anxiety in a nonclinical sample. Subjects (N = 526) receiving a medical check-up were assessed with the Hospital del Mar hypermobility criteria and the State-Trait Anxiety Inventory. Scores for trait anxiety, and to a lesser extent state anxiety, were significantly higher among subjects with joint hypermobility syndrome than among subjects without this syndrome (median trait anxiety scores for women: 17 versus 11; median scores for men: 13 versus 1). These findings indicate that the association of joint hypermobility syndrome and anxiety holds even for subjects with no psychiatric diagnosis. Therefore, it seems that this benign connective tissue disorder is a predisposing factor for trait anxiety. However, it is necessary to further explore and define the biological basis of this syndrome, as well as its associations and clinical expressions, which interact with great complexity.

Adult↗
PubMedDate not supplied

Persistent toxic substances and public health in Spain.

In Spain, there are substantial gaps in available information about contamination of food, humans, and the environment by persistent toxic substances (PTSs), although studies have shown detectable concentrations of DDE, PCBs, hexachlorobenzene, or hexachlorocyclohexane in 80-100% of the population. Spain will soon try to implement the Stockholm treaty on persistent organic pollutants (POPs). A country that ratifies the treaty is required to develop a National Implementation Plan (NIP). Such NIPs should provide for studies of factors that influence body concentrations of PTSs in the population, and thus ultimately reduce PTS data gaps. Spain's PTS-related problems are similar to those of many other countries. Elucidation of their causes, consequences, and possible solutions will be of benefit beyond national boundaries.

Environmental Exposure↗