Miguel Santibáñez

Occupational risk factors in Alzheimer's disease: a review assessing the quality of published epidemiological studies

Epidemiological evidence of an association between Alzheimers disease AD and the most frequently studied occupational exposurespesticides, solvents, electromagnetic fields EMF, lead and aluminiumis inconsistent. Epidemiological studies published up to June of 2003 were systematically searched through PubMed and Toxline. Twenty-four studies 21 casecontrol and 3 cohort studies were included. Median GQI was 36.6 range 19.562.9. Most of the casecontrol studies had a GQI of <50. The study with the highest score was a cohort study. Likelihood of exposure misclassification bias affected 18 of the 24 studies. Opportunity for bias arising from the use of surrogate informants affected 17 studies, followed by disease misclassification 11 studies and selection bias 10 studies. Eleven studies explored the relationship of AD with solvents, seven with EMF, six with pesticides, six with lead and three with aluminium. For pesticides, studies of greater quality and prospective design found increased and statistically significant associations. For the remaining occupational agents, the evidence of association is less consistent for solvents and EMF or absent for lead and aluminium.

Esophageal cancer risk by type of alcohol drinking and smoking: a case-control study in Spain

BackgroundThe effect of tobacco smoking and alcohol drinking on esophageal cancer (EC) has never been explored in Spain where black tobacco and wine consumptions are quite prevalent. We estimated the independent effect of different alcoholic beverages and type of tobacco smoking on the risk of EC and its main histological cell type (squamous cell carcinoma) in a hospital-based case-control study in a Mediterranean area of Spain.MethodsWe only included incident cases with histologically confirmed EC (n = 202). Controls were frequency-matched to cases by age, sex and province (n = 455). Information on risk factors was elicited by trained interviewers using structured questionnaires. Multiple logistic regression was used to estimate adjusted odds ratios and 95% confidence intervals (CI).ResultsAlcohol drinking and tobacco smoking were strong and independent risk factors for esophageal cancer. Alcohol was a potent risk factor with a clear dose-response relationship, particularly for esophageal squamous-cell cancer. Compared to never-drinkers, the risk for heaviest drinkers (≥ 75 g/day of pure ethanol) was 7.65 (95%CI, 3.16–18.49); and compared with never-smokers, the risk for heaviest smokers (≥ 30 cigarettes/day) was 5.07 (95%CI, 2.06–12.47). A low consumption of only wine and/or beer (1–24 g/d) did not increase the risk whereas a strong positive trend was observed for all types of alcoholic beverages that included any combination of hard liquors with beer and/or wine (p-trend<0.00001). A significant increase in EC risk was only observed for black-tobacco smoking (2.5-fold increase), not for blond tobacco. The effects for alcohol drinking were much stronger when the analysis was limited to the esophageal squamous cell carcinoma (n = 160), whereas a lack of effect for adenocarcinoma was evidenced. Smoking cessation showed a beneficial effect within ten years whereas drinking cessation did not.ConclusionOur study shows that the risk of EC, and particularly the squamous cell type, is strongly associated with alcohol drinking. The consumption of any combination of hard liquors seems to be harmful whereas a low consumption of only wine may not. This may relates to the presence of certain antioxidant compounds found in wine but practically lacking in liquors. Tobacco smoking is also a clear risk factor, black more than blond.

Occupational exposures and risk of stomach cancer by histological type

Objective To explore the relationship between stomach cancer (SC), by histological type, and occupations and occupational exposures. Methods The authors conducted a hospital-based case–control study in south-east Spain. Subjects were 399 incident histological confirmed SC cases (241 intestinal and 109 diffuse adenocarcinomas) and 455 controls frequency matched by sex, age and province of residence. Occupation was coded according to the Spanish National Classification of Occupations 1994. Occupational exposures were assessed by the FINJEM Job Exposure Matrix. ORs were estimated by unconditional logistic regression adjusting for matching variables and education, smoking, alcohol and diet. Results In men, statistically significant increased risk of the diffuse subtype was found for ‘cooks’ (OR 8.02), ‘wood-processing-plant operators’ (OR 8.13) and ‘food and related products machine operators’ (OR 5.40); for the intestinal subtype, a borderline association was found for ‘miners and quarry workers’ (OR men 4.22, 95% CI 0.80 to 22.14). Significant increased risk was observed between the diffuse subtype of SC and the highest level of exposure to ‘pesticides’ (ORH both sexes 10.39, 95% CI 2.51 to 43.02, ptrend=0.02) and between the intestinal subtype and asbestos (ORH men 3.71, 95% CI 1.40 to 9.83, ptrend=0.07). Restricted analyses of exposures of 15 years and longer showed significant associations between the diffuse subtype and the exposure to ‘wood dust’ (OR men 3.05). Conclusions This study supports the relationship previously suggested between SC and occupational exposure to dusty and high temperature environments. Several occupations may also increase the risk of diffuse SC but not the intestinal subtype.

Real-Time PCR for Diagnosing Helicobacter pylori Infection in Patients with Upper Gastrointestinal Bleeding: Comparison with Other Classical Diagnostic Methods

ABSTRACT The aim of this study was to determine the diagnostic usefulness of quantification of the H. pylori genome in detection of infection in patients with upper gastrointestinal bleeding (UGB). A total of 158 consecutive patients with digestive disorders, 80 of whom had clinical presentation of UGB, were studied. The number of microorganisms was quantified using a real-time PCR system which amplifies the urease gene with an internal control for eliminating the false negatives. A biopsy sample from the antrum and corpus of each patient was processed. The rapid urease test, culture, histological study, stool antigen test, and breath test were done. The gold standard was a positive culture or positive results in at least two of the other techniques. When a positive result was defined as any number of microorganisms/human cell, the sensitivity of real-time PCR was greater in bleeding patients, especially in the gastric corpus: 68.4% (95% confidence interval [CI], 52.3 to 84.5%) in non-UGB patients versus 91.5% (95% CI, 79.6 to 97.6%) in UGB patients. When a positive result was defined as a number of microorganisms/human cell above the optimal value that maximizes the Youden index (>3.56 microorganisms/human cell in the antrum and >2.69 in the corpus), the sensitivity and specificity in UGB patients were over 80% in both antrum and corpus. Our findings suggest that some bleeding patients with infection caused by H. pylori may not be correctly diagnosed by classical methods, and such patients could benefit from the improved diagnosis provided by real-time PCR. However, the clinical significance of a small number of microorganisms in patients with negative results in classical tests should be evaluated.

Shared Oncogenic Pathways Implicated in Both Virus-Positive and UV-Induced Merkel Cell Carcinomas

Merkel cell carcinoma (MCC) is a highly malignant neuroendocrine tumor of the skin whose molecular pathogenesis is not completely understood, despite the role that Merkel cell polyomavirus can play in 55-90% of cases. To study potential mechanisms driving this disease in clinically characterized cases, we searched for somatic mutations using whole-exome sequencing, and extrapolated our findings to study functional biomarkers reporting on the activity of the mutated pathways. Confirming previous results, Merkel cell polyomavirus-negative tumors had higher mutational loads with UV signatures and more frequent mutations in TP53 and RB compared with their Merkel cell polyomavirus-positive counterparts. Despite important genetic differences, the two Merkel cell carcinoma etiologies both exhibited nuclear accumulation of oncogenic transcription factors such as NFAT or nuclear factor of activated T cells (NFAT), P-CREB, and P-STAT3, indicating commonly deregulated pathogenic mechanisms with the potential to serve as targets for therapy. A multivariable analysis identified phosphorylated CRE-binding protein as an independent survival factor with respect to clinical variables and Merkel cell polyomavirus status in our cohort of Merkel cell carcinoma patients.

Sputum microbiota in moderate versus severe patients with COPD

To the Editor: The emergence of new massive sequencing methods has proved revolutionary for the study of complex microbial populations such as the microbiota of the respiratory tract in patients with chronic obstructive pulmonary disease (COPD) [1]. Using this powerful methodology, our objective was to compare the microbiota in two groups of patients with COPD of different severity in order to detect potential microbiological markers that could help to provide a better understanding of the pathogenesis of this disease and the role played by the microbiota in its severity. The current study recruited nine patients with mild or moderate COPD and 10 patients with severe or very severe COPD in a stable condition (at least 3 months without exacerbation or use of antibiotics for any other reason). Diagnosis and classification of COPD was established according to Global Initiative for Chronic Obstructive Lung Disease (GOLD) recommendations [2]. After DNA extraction from good quality expectorated sputum, quantitative (q)PCR (7500 real time PCR system thermocycler; Life Technologies, Grand Island, NY, USA) was used to quantify the copy number of the 16S rRNA gene in each sample (total bacterial load), yielding a 468 bp amplicon located between nucleotides 340–808 in reference to the 16S rRNA gene of Escherichia coli strain MG1655 (National Center for Biotechnology Information (NCBI) reference sequence: NR_102804.1). In order to compare the results obtained, they were normalised to the number of human cells in the sample, quantified by qPCR, using the human albumin gene [3]. A region measuring 525 bp, between position 8 and 533 of the 16S rRNA gene was amplified and pyrosequenced (Roche GS FLX Titanium with Lib-L type microspheres; 454 Life Sciences, Branford, CT, USA). This region comprises the regions of gene hypervariability from V1 to V3 of the 16S rRNA gene …

Microbiological Diagnosis of Sepsis: Polymerase Chain Reaction System Versus Blood Cultures

OBJECTIVE To compare the utility of a multiplex polymerase chain reaction system (SeptiFast) and blood cultures for detecting bacteria and fungi in blood samples from patients with severe sepsis or septic shock. METHODS In a prospective observational study, whole blood samples for SeptiFast testing and for culture were collected on admission from all patients with severe sepsis or septic shock admitted to the intensive care unit between July 2011 and September 2012. SeptiFast results were compared with blood and other culture results. RESULTS The probability of at least 1 microorganism being isolated at 6 hours was 13-fold higher with the SeptiFast test than with blood cultures (relative risk, 13.5; 95% CI, 5.05-36.06). Unlike culture results, SeptiFast test results were not associated with previous antibiotic consumption. The median time to the first positive blood culture result was 17 hours; SeptiFast results were available in 6 hours. SeptiFast detected genetic material from potentially multiresistant microorganisms in patients whose blood cultures showed no growth at all. CONCLUSIONS The SeptiFast test provided quicker microbiological diagnosis and identified significantly more microorganisms than blood cultures did, particularly when samples were collected after antibiotic therapy had started or infections were due to resistant bacteria and yeast.

Relationship between tobacco, cagA and vacA i1 virulence factors and bacterial load in patients infected by Helicobacter pylori.

Background and Aim Several biological and epidemiological studies support a relationship between smoking and Helicobacter pylori (H. pylori) to increase the risk of pathology. However, there have been few studies on the potential synergistic association between specific cagA and vacA virulence factors and smoking in patients infected by Helicobacter pylori. We studied the relationship between smoking and cagA, vacA i1 virulence factors and bacterial load in H. pylori infected patients. Methods Biopsies of the gastric corpus and antrum from 155 consecutive patients in whom there was clinical suspicion of infection by H. pylori were processed. In 106 patients H. pylori infection was detected. Molecular methods were used to quantify the number of microorganisms and presence of cagA and vacA i1 genes. A standardized questionnaire was used to obtain patients’ clinical data and lifestyle variables, including tobacco and alcohol consumption. Adjusted Odds Ratios (ORadjusted) were estimated by unconditional logistic regression. Results cagA was significantly associated with active-smoking at endoscope: ORadjusted 4.52. Evidence of association was found for vacA i1 (ORadjusted 3.15). Bacterial load was higher in active-smokers, although these differences did not yield statistical significance (median of 262.2 versus 79.4 copies of H. pylori per cell). Conclusions The association between smoking and a higher risk of being infected by a virulent bacterial population and with higher bacterial load, support a complex interaction between H. pylori infection and environmental factors.

Analysis of microbiota in stable patients with chronic obstructive pulmonary disease

To identify the bacterial diversity (microbiota) in expectorated sputum, a pyrosequencing method that investigates complex microbial communities of expectorated sputum was done in 19 stable chronic obstructive pulmonary disease patients (mean (SD) FEV1: 47 (18%) of predicted value). Using conventional culture, 3 phyla and 20 bacterial genera were identified, whereas the pyrosequencing approach detected 9 phyla and 43 genera (p < 0.001). In sputum the prevalent genera with pyrosequencing approach were Streptococcus, Actinomyces, Neisseria, Haemophilus, Rothia, Fusobacterium, Gemella, Granulicatella, Porphyromonas, Prevotella and Veillonella. Enterobacteriaceae, detected frequently in conventional culture, were not significantly detected with pyrosequencing methods. In addition, we found that important pathogens such as Haemophilus and Moraxella were detected more frequently with the new genetic procedures. The presence of Enterobacteriaceae is probably overestimated with conventional culture, whereas other difficult cultivable pathogens are underestimated. These studies open a new perspective for evaluating the role of bacterial colonization in chronic obstructive pulmonary disease pathogenesis and progression.

Quantification of Helicobacter pylori in gastric mucosa by real-time polymerase chain reaction: comparison with traditional diagnostic methods ☆ ☆☆

The aim of this study was to determine the main diagnostic validity parameters of a quantitative real-time polymerase chain reaction (PCR) system for detecting Helicobacter pylori in gastric biopsies. Prospective study. The real-time PCR has an internal control for eliminating the false negatives. Our system has a good diagnostic capacity compared with the gold standard and was superior in antral mucosa: area under the curve was 0.91 for antrum (95% confidence interval [CI] 0.87 to 0.96) and 0.83 for corpus (95% CI 0.77 to 0.9). The optimum cut-off point was 3.56 microorganisms/cell for antrum (sensitivity 83.5% [95% CI 74.2 to 89.9]; specificity 91.3% [95% CI 82.3 to 96.0]; positive predictive value 92.2%; negative predictive value 81.8%). The positive likelihood ratios were 9.61 and 8.52 for antrum and corpus, respectively. With the cut-off point that maximises the Youden index, 8.7% false positives were obtained. Our methodology is useful for diagnosing infection due to H. pylori and the false positives detected probably correspond to patients who were actually infected but the infection was not detected by traditional techniques. The clinical importance of these cases should be studied in greater detail since they may involve colonisations unrelated to the patients digestive pathology.