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Miquel Porta

Publications and source records attributed to Miquel Porta.

At least 19 recordsLinked to original sources
PubMed2006

Estimating dietary intakes from a brief questionnaire: A simulation study of reliability in a molecular epidemiologic study of pancreatic and biliary diseases.

INTRODUCTION: Brief dietary questionnaires may be useful in research or clinical settings where in-depth assessments are inefficient or impractical. We conducted a simulation study to assess the reliability of a brief food frequency questionnaire (bFFQ) for capturing dietary intakes relative to a detailed survey. SUBJECTS AND METHODS: The bFFQ was used in a study of patients with pancreatic and biliary diseases in eastern Spain (n = 605). The structured interview included a section probing the frequency of intakes of 14 food groups, using 4 response categories. Data from a 93-item semi-quantitative food frequency questionnaire (SFFQ) with 9 response categories (n = 1337) was used to: (1) develop estimates of nutrient intakes for each food group, and (2) to simulate how intakes would have been estimated using the bFFQ. The simulation allowed to assess effects of aggregating foods and using abbreviated frequency categories. RESULTS: Correlations between actual and simulated intake frequencies exceeded 0.70 for 10 food groups; modest correlations (0.43-0.56) were observed for groups assessed less well using abbreviated frequency categories. Correlations exceeded 0.60 for most nutrients. Concordance was lower for several nutrients, notably retinol, for which substantial proportions were contributed by groups combining foods with highly variable levels of these compounds. CONCLUSIONS: Intake estimates from the bFFQ may be useful in exploratory analyses of the role of diet in bilio-pancreatic diseases and related etiopathogenic events. Estimates for some nutrients may be less reliable, and should be interpreted with particular caution.

Adult↗
PubMed2006

Book citations: influence of epidemiologic thought in the academic community.

Whilst their 'death' has often been certified, books remain highly important to most professions and academic disciplines. Analyses of citations received by epidemiologic texts may complement other views on epidemiology. The objective was to assess the number of citations received by some books of epidemiology and public health, as a first step towards studying the influence of epidemiological thought and thinking in academia. For this purpose, Institute for Scientific Information/ Thomson Scientific - Web of Science/ Web of Knowledgedatabase was consulted, in May 2006. The book by Rothman & Greenland appeared to have received the highest number of citations overall (over 8,000) and per year. The books by Kleinbaum et al, and by Breslow & Day received around 5,000 citations. In terms of citations per year the book by Sackett et al ranks 3rd, and the one by Rose, 4th of those included in this preliminary study. Other books which were influential in the classrooms collected comparatively less citations. Results offer a rich picture of the academic influences and trends of epidemiologic methods and reasoning on public health, clinical medicine and the other health, life and social sciences. They may contribute to assess epidemiologists' efforts to demarcate epidemiology and to assert epistemic authority, and to analyze some historical influences of economic, social and political forces on epidemiological research.

Bibliometrics↗
PubMed2005

Certification of occupational diseases as common diseases in a primary health care setting.

BACKGROUND: It is often difficult to discern whether a disease is an occupational or common disease, especially in a primary care setting. METHODS: From a randomly selected sample of 322 workers attending a Primary Health Care Center, 207 workers (response rate of 64.3%) agreed to participate. An occupational questionnaire was administered. General practitioners provided medical records for each worker. Medical records and occupational questionnaires were independently reviewed by three professionals. They assessed whether a relationship between disease and working conditions was probable or improbable. RESULTS: Thirty-three of the 207 cases (15.9%) were considered probably related to working conditions according to the expert's opinion. The most frequent were musculoskeletal diseases (20 cases). Of the 207 workers, 74 (35.7%) judged that their diseases could be related to their working conditions. CONCLUSIONS: A significant proportion of diseases attended in primary care setting was not recognized as occupational, and they were hence not reflected in official statistics.

Adult↗
PubMed2005

Exocrine pancreatic cancer: symptoms at presentation and their relation to tumour site and stage.

INTRODUCTION: The need to detect pancreatic cancer at earlier stages is undisputed. We recorded the signs and symptoms of patients presenting with exocrine pancreatic cancer and evaluated their association with clinical characteristics such as tumour site and disease stage. PATIENTS AND METHODS: All patients (n = 185) with exocrine pancreatic cancer newly diagnosed at five general hospitals in Eastern Spain were prospectively recruited over 5 years. Symptoms were elicited through personal interviews and signs were recorded by the attending physician on admission. RESULTS: At diagnosis, one third of tumours of the pancreas head were in stage I and another third in stage IV. None of the tumours of the body and tail were in stage I, and over 80% were in stage IV (p < 0.001) . At presentation, the most frequent symptoms were asthenia (86%), anorexia (85%), weight-loss (85%), abdominal pain (79%), and choluria (59%). Cholestatic symptoms were more common in tumours affecting only the pancreatic head (p < 0.001) . There was a clear trend toward more localized tumours with increasing numbers of cholestatic signs (p < 0.001) . Asthenia, anorexia and weight-loss were unrelated to stage. An increased symptom-to-diagnosis interval was associated with more advanced stage (p = 0.048). CONCLUSIONS: Proper attention to signs and symptoms, especially cholestasis, may help identify patients with pancreatic cancer at an earlier stage. Results also provide a current picture of the semiology of pancreatic cancer which could be of use in studies on the potential of proteomic tests in the early detection of this neoplasm.

Aged↗
PubMed2004

Mixing journal, article, and author citations, and other pitfalls in the bibliographic impact factor.

News of the death of biomedical journals seem premature. Revamped traditional scientific journals remain highly valued sources and vehicles of information, critical debate, and knowledge. Some analyses seem to place a disproportionate emphasis on technological and formal issues, as compared to the importance ascribed to matters of power. Not all journals must necessarily have a large circulation. There are many examples of efficient, high-quality journals with a great impact on relatively small audiences for whom the journal is thought-provoking, useful, and pleasant to read. How can we achieve a better understanding of an article s spectrum of impacts? A certain mixing of three distinct entities (journals, articles, and authors) has often pervaded judgments. Data used by the Institute for Scientific Information present weaknesses in their accuracy. The two-year limit for citations to count towards the bibliographic impact factor favors "fast-moving", "basic" biomedical disciplines and is less appropriate for public health studies. Increasing attention is given to the specific number of citations received by each individual article. It is possible to make progress towards more valid, accurate, fair, and relevant assessments.

Authorship↗
PubMed2004

[The impact of the Prestige disaster on human health].

The worst environmental disaster of the history of Spain favoured a renewed social awareness of the intimate relationships that exist between the state of the environment and the health of human beings. However, the health of the populations most involved in the Prestige oil spill was initially not the chief concern of political authorities. The main aims of the present paper are: first, to comment succinctly on some of the most significant activities conducted by a variety of social actors during the Prestige crisis; and second, to suggest the main potential objectives and characteristics of the epidemiological studies necessary to assess with a sound rational basis the possible impact of the accident on the health of workers, volunteers and residents in the spill areas. The authors hope that in the near future it will be possible to scientifically assess the results and implications of several studies (epidemiological and of other sorts) well designed and conducted.

Disasters↗
PubMed2003

Occupational exposure to dyes, metals, polycyclic aromatic hydrocarbons and other agents and K-ras activation in human exocrine pancreatic cancer.

ras genes are known critical DNA targets for chemical carcinogens. Exocrine pancreatic cancer (EPC) is the human tumor with the highest prevalence of K-ras mutations at diagnosis. We analyzed the relationship between past occupational exposure to dyes, metals, polycyclic aromatic hydrocarbons (PAHs) and other agents and mutations in codon 12 of the K-ras gene in 107 incident cases of EPC. Information on occupational and life-style factors was obtained from personal interviews conducted during hospital stay. Occupational exposures were examined using industrial hygienists (IH) assessment and the Finnish job-exposure matrix (Finjem). Specific occupational exposures among K-ras mutated EPC cases (n = 83) were compared to those of K-ras wild-type EPC cases (n = 24) (case-case analysis). Multivariate-adjusted odds ratios (OR) and their corresponding 95% confidence limits were estimated by unconditional logistic regression. Cases with K-ras mutations were significantly more likely than wild-type cases to have been exposed to dyes and organic pigments (OR 4.8; p<0.05). There was some indication of weaker associations between K-ras mutations and occupational exposure to lead, PAHs, benzo[a]pyrene, gasoline, nickel, inhalatory exposure to chromium and sedentary work. The association with chromium compounds was stronger for G to T transversions, a finding compatible with experimental studies on mutation spectra for chromium. Results lend moderate support to the hypothesis of indirect relationships between occupational exposure to dyes and organic pigments and the activation of the K-ras gene in the etiopathogenesis of human exocrine pancreatic cancer.

Asbestos↗
PubMed2003

Exploring environmental causes of altered ras effects: fragmentation plus integration?

Mutations in ras genes are the most common abnormality of oncogenes in human cancer and a major example of activation by point mutation. Experimental and epidemiological studies support the notion that Ki-ras activation and expression may be chemically related. We discuss the potential role of several environmental compounds in the induction or promotion of ras mutations in humans, with a focus on exocrine pancreatic cancer, the human tumor with the highest prevalence at diagnosis of Ki-ras mutations. Organochlorine compounds, organic solvents, and coffee compounds may play an indirect role in causing Ki-ras mutations, rather than as direct inducers of the mutations. Although for some organochlorine compounds the induction of point mutations in ras oncogenes cannot be excluded, it seems more likely that the effects of these compounds are mediated through nongenomic or indirectly genotoxic mechanisms of action. Organic solvents also may act via enzymatic induction of ras mutagens or by providing a proliferation advantage to ras-mutated cell clones. In exocrine pancreatic cancer, caffeine, other coffee compounds, or other factors with which coffee drinking is associated could modulate Ki-ras activation by interfering with DNA repair, cell-cycle checkpoints, and apoptosis. Asbestos, cigarette smoking, and some dietary factors also may be involved in the initiation or the promotion of Ki-ras mutations in lung and colon cancers. Further development of the mechanistic scenarios proposed here could contribute to a meaningful integration of biological, clinical, and environmental knowledge on the causes of altered ras effects.

Coffee↗
PubMed2003

Semiology, proteomics, and the early detection of symptomatic cancer.

"Diagnostic delay," the duration of symptoms or the symptom to diagnosis interval (SDI), are highly complex variables that reflect the behavior of the patient and the attending physician, tumor biology and host-tumor interactions, the functioning of the health care system, and sociocultural norms. In addition to tumor stage, other variables mediate the relationship between duration of symptoms and survival; clinical and epidemiologic procedures to measure them must be improved. Largely at odds with clinical and common wisdom, decades of research have shown that often SDI is not associated with tumor stage and/or with survival from cancer. It would be relevant to increase evidence in support of the notion that, for each type of tumor, there is a positive relationship between the length of the presymptomatic and the symptomatic phases. SDI could then be used to classify tumors according to their likelihood of being detected early when still asymptomatic. Also, tumors could be classified according to the ratio of the median SDI to the median survival (SDI to survival ratio, SSR), which may estimate the relative likelihood for clinical lead-time bias. If adhering to rigorous methodologic standards, proteomic analyses of early-stage cancers might provide new insights into changes that occur in early phases of tumorigenesis. More real examples are needed of uses of pathologic and genomic data to study mechanisms through which SDI influences-or fails to influence-prognosis. The degree of correlation between proteomic patterns and classic semiology constitutes an area of interest in itself; their respective correlations with cancer prognosis should be assessed in properly designed epidemiologic studies.

Humans↗