Adverse health effects of selenium in humans

Epidemiologic studies and case reports have shown that chronic exposure to selenium compounds is associated with several adverse health effects in humans. An early toxic effect of selenium is on endocrine function, particularly on the synthesis of thyroid hormones following dietary exposure of around 300 micrograms Se/d, and on the metabolism of growth hormone and insulin-like growth factor-1. Other adverse effects of selenium exposure can be the impairment of natural killer cells activity and at higher levels, hepatotoxicity and gastrointestinal disturbances. Dermatologic effects, such as nail and hair loss and dermatitis, occur after exposure to high levels of environmental selenium. Assessing the toxicity and morbidity after long-term exposure to environmental selenium is difficult: neurotoxicity, particularly the degeneration of motor neurons leading to increased risk of amyotrophic lateral sclerosis, might occur after chronic exposure to both organic and inorganic selenium compounds. The results of laboratory investigations and cohort studies suggest that selenium species exhibit a bivalent effect in cancer, either increasing or decreasing risk. Current environmental selenium exposure limits appear to be inadequate for averting adverse health effects.     

Inverse association between dietary vitamin D and risk of cutaneous melanoma in a northern Italy population

The possibility of an inverse association between vitamin D and risk of cancer and, in particular, of cutaneous malignant melanoma has been suggested, but results of epidemiologic studies are still conflicting. We examined the relation between dietary vitamin D intake and melanoma risk through a population-based case-control study (380 cases, 719 controls) in a northern region of Italy, a country with an average vitamin D intake lower than that in northern Europe or the United States. We assessed average daily intake of vitamin D from foodstuffs using the European Prospective Investigation into Cancer and Nutrition (EPIC) semiquantitative food frequency questionnaire. In this population, levels of vitamin D intake were considerably lower than those observed in recent U.S. studies. We found an inverse relation between dietary vitamin D and melanoma risk in the sample as a whole, in both crude and adjusted analyses. In sex- and age-specific analyses, this association appeared to be stronger among males and among older subjects. These findings suggest that, at the relatively low levels of intake observed in this sample, an inverse relation between dietary vitamin D and risk of cutaneous malignant melanoma may exist.     

Comparison between genotype and phenotype identifies a high-risk population carrying BRCA1 mutations

Hereditary breast carcinomas constitute about 10% of all malignant mammary tumors, but the selection criteria to identify a high-risk population carrying BRCA1 mutations are not yet well-defined. We have collected 51 pedigrees of familial breast cancer, 16 pedigrees of familial breast and ovarian cancer, and 30 cases of early-onset breast cancer (<35 years of age) without any family history of breast cancer. The index cases of the 97 selected families were further subdivided into three groups based on histopathological parameters: group A (n = 19) was characterized by tumor grade III, negative estrogen and progesterone receptors, and high proliferative rate; group B (n = 20) was characterized by grade I-II tumors, positive hormonal receptors, and low proliferative rate; and group C (n = 58) was not homogeneous for the histopathological criteria. The aim of our study was to evaluate, in patients with a family history of breast cancer or with early diagnosis of breast cancer, the incidence of BRCA1 mutation on the basis of tumor phenotype. We found the highest rate of BRCA1 mutations in group A (53%), and low frequencies in groups B (5%) and C (0%). Our data strongly indicate that an aggressive tumor phenotype in patients with a positive family history or early diagnosis identifies a population with high probability of carrying BRCA1 mutations. Genes Chromosomes Cancer 27:130-135, 2000.     

Sodium and Potassium Content of Foods Consumed in an Italian Population and the Impact of Adherence to a Mediterranean Diet on Their Intake

High sodium and low potassium intakes are associated with increased levels of blood pressure and risk of cardiovascular diseases. Assessment of habitual dietary habits are helpful to evaluate their intake and adherence to healthy dietary recommendations. In this study, we determined sodium and potassium food-specific content and intake in a Northern Italy community, focusing on the role and contribution of adherence to Mediterranean diet patterns. We collected a total of 908 food samples and measured sodium and potassium content using inductively coupled plasma mass spectrometry. Using a validated semi-quantitative food frequency questionnaire, we assessed habitual dietary intake of 719 adult individuals of the Emilia-Romagna region. We then estimated sodium and potassium daily intake for each food based on their relative contribution to the overall diet, and their link to Mediterranean diet patterns. The estimated mean sodium intake was 2.15 g/day, while potassium mean intake was 3.37 g/day. The foods contributing most to sodium intake were cereals (33.2%), meat products (24.5%, especially processed meat), and dairy products (13.6%), and for potassium they were meat (17.1%, especially red and white meat), fresh fruits (15.7%), and vegetables (15.1%). Adherence to a Mediterranean diet had little influence on sodium intake, whereas potassium intake was greatly increased in subjects with higher scores, resulting in a lower sodium/potassium ratio. Although we may have underestimated dietary sodium intake by not including discretionary salt use and there may be some degree of exposure misclassification as a result of changes in food sodium content and dietary habits over time, our study provides an overview of the contribution of a wide range of foods to the sodium and potassium intake in a Northern Italy community and of the impact of a Mediterranean diet on intake. The mean sodium intake was above the dietary recommendations for adults of 1.5–2 g/day, whilst potassium intake was only slightly lower than the recommended 3.5 g/day. Our findings suggest that higher adherence to Mediterranean diet patterns has limited effect on restricting sodium intake, but may facilitate a higher potassium intake, thereby aiding the achievement of healthy dietary recommendations.     

Factors predicting disease progression in C9ORF72 ALS patients

Journal of Neurology - To unveil clinical features, comorbidities, disease progression and prognostic factors in a population-based cohort of ALS patients carrying C9ORF72 expansion...     

The epidemiology of selenium and human cancer

The relation between the trace element selenium and the etiology of cancer in humans remains elusive and intriguing, despite the number of epidemiologic studies published on the topic. We address some methodologic issues, such as misclassification of exposure, particularly to single selenium compounds, effect modification, confounding, and other sources of bias, which may explain the inconsistencies in the literature. We also review the results of cohort studies, which have yielded either inverse or null or direct associations between selenium exposure and subsequent cancer risk. To date, no beneficial effect on cancer incidence at major sites, including prostate cancer, has emerged from the Finnish program begun in 1984 to increase the average selenium intake in its population. Populations exposed to unusually high or low levels of environmental selenium might offer unique opportunities to investigate if selenium exposure is related to the etiology of human cancer.     

Risk of sporadic amyotrophic lateral sclerosis associated with seropositivity for herpesviruses and echovirus-7

We examined the association between risk of sporadic amyotrophic lateral sclerosis (ALS) and seroprevalence of antibodies to echovirus-7 (echo-7) and herpesviruses 6, 7, and 8 through a population-based case–control study. We enrolled in a northern Italy area 20 newly diagnosed ALS cases and 20 referents. Risk of ALS was higher in subjects seropositive for echo-7 when we used the immunofluorescent assay, while little increase was noted with the neutralization test. Considering the different characteristics of these two serological assays, these results suggest an association between disease risk and infection with enterovirus (EV) family members (not specifically echo-7). ALS risk was slightly associated with seropositivity of human herpesvirus-6 (odds ratio: 3.2; p = 0.102) and more strongly with human herpesvirus-8 seropositivity (odds ratio: 8.4, p = 0.064), though these point estimates were statistically unstable due to the limited number of observed cases. The findings of this study warrant further investigation in larger studies of the possible etiologic role of EV or herpesvirus infection in sporadic ALS.     

Low back pain risk in nurses and its prevention

We present the results of a study on the prevalence of low back pain (LBP) in a group of hospital nursing personnel. In 180 subjects (89% women) a questionnaire on LBP was collected. The prevalence of LBP episodes during the last 12 months was 63,9%; no difference was observed according to the working area (medicine, surgery, emergency). The proportion of subjects with LBP tended to increase according to the previous duration of work, but not with age. The prevalence of LBP was significantly lower in nursing personnel working according the team nursing model, that is less repetitive, and involves less work load, compared to the functional nursing model. Furthermore, LBP prevalence was lower among nurses that received an adequate formation on the prevention of occupational LBP. The results of the study confirm the relevance of LBP in nursing personnel, but suggest also that an adequate preventive programme can significantly reduce the risk.