Biomedical subjects

Dorothea Alber

Publications and source records attributed to Dorothea Alber.

5 recordsLinked to original sources

PubMed2005

Trace elements and melanoma.

Melanoma incidence has been steadily increasing in recent years in most western countries, thus suggesting a role of environmental risk factors. Among these determinants, it has been hypothesized that some trace elements of nutritional and toxicological interest may be implicated in the etiology of the disease. We examined patients with newly diagnosed melanoma of the skin and population controls from the Modena province northern Italy. Clinical and dietary data were collected through questionnaires, and toenails were sampled for trace element determination. Levels of cadmium, chromium, lead, selenium, zinc, copper and iron in toenails were measured by inductively coupled plasma optical emission spectrometry and by neutron activation analysis. Data obtained from 58 cases and 58 controls indicated higher levels of copper and lower concentrations of iron in melanoma patients, whilst no other differences were seen for the remaining elements. Patterns of correlations of zinc and copper with the estimated intake of some dietary factors were different between cases and controls. Results of the present study suggest that abnormal intake or metabolism of copper and of iron might be implicated in the etiology of melanoma, whilst they do not indicate an involvement of exposure to cadmium, chromium, lead, selenium and zinc in this disease.

Case-Control Studies↗

PubMed2005

Environmental exposure to trace elements and risk of cutaneous melanoma.

PURPOSE: Our aim was to examine the risk of melanoma in association with exposure to trace elements of toxicological and nutritional interest. METHODS: We analyzed the concentrations of cadmium, lead, chromium, selenium, copper and zinc in toenails of 58 patients with newly diagnosed cutaneous melanoma as well as in 58 age- and sex-matched control subjects, randomly selected from the population of Modena province in northern Italy. RESULTS: Melanoma risk was substantially unrelated to toenail levels of cadmium, chromium, lead and selenium. Subjects with higher toenail copper levels showed an excess risk, both in the crude analysis and after adjusting for sun exposure and level of education, while in both analyses high iron concentrations were associated with a decreased risk of the disease. A weak direct association between zinc levels and melanoma risk also emerged in the multivariate analysis. CONCLUSIONS: Overall, these results do not suggest an involvement of heavy metals in melanoma etiology, while they do give some support to a possible role of zinc and, in particular, copper and iron exposure in influencing disease risk. However, these findings must be evaluated with caution due to the limited statistical stability of the point estimates.

Case-Control Studies↗

PubMed2003

Physical and chemical limitations to preparation of beta radioactive stents by direct neutron activation.

Pure beta emitters are the sources of choice for intracoronary irradiations in restenosis prevention. In this work we reconsidered preparation of low activity 32P sources by ion-implantation of stable 31P into highly biocompatible pure titanium stents, followed by neutron activation. Gamma-spectrometrical analysis has shown that during activations with high thermal neutrons flux production of gamma-active long-lived contaminants is much beyond the dosimetrically acceptable limit, mainly due to the competing (n,p) reactions induced by the fast neutrons on isotopes of the bulk stent material, and to a lesser extent due to (n,gamma) reactions on chemical impurities. A potential applicability of this method for obtaining alternative beta radioactive stents is discussed.

Brachytherapy↗

PubMed2002

Adenosine triphosphate-induced electron transfer in 2-hydroxyglutaryl-CoA dehydratase from Acidaminococcus fermentans.

2-hydroxyglutaryl-CoA dehydratase from Acidaminococcus fermentans catalyzes the chemical difficult elimination of water from (R)-2-hydroxyglutaryl-CoA to glutaconyl-CoA. The enzyme consists of two oxygen-sensitive protein components, the homodimeric activator (A) with one [4Fe-4S]1+/2+ cluster and the heterodimeric dehydratase (D) with one nonreducible [4Fe-4S]2+ cluster and reduced riboflavin 5'-monophosphate (FMNH2). For activation, ATP, Mg2+, and a reduced flavodoxin (16 kDa) purified from A. fermentans are required. The [4Fe-4S](1+/2+) cluster of component A is exposed to the solvent since it is accessible to iron chelators. Upon exchange of the bound ADP by ATP, the chelation rate is 8-fold enhanced, indicating a large conformational change. Oxidized component A exhibits ATPase activity of 6 s(-1), which is completely abolished upon reduction by one electron. UV-visible spectroscopy revealed a spontaneous one-electron transfer from flavodoxin hydroquinone (E(0)' = -430 mV) to oxidized component A, whereby the [4Fe-4S]2+ cluster of component A became reduced. Combined kinetic, EPR, and Mössbauer spectrocopic investigations exhibited an ATP-dependent oxidation of component A by component D. Whereas the [4Fe-4S]2+ cluster of component D remained in the oxidized state, a new EPR signal became visible attributed to a d1-metal species, probably Mo(V). Metal analysis with neutron activation and atomic absorption spectroscopy gave 0.07-0.2 Mo per component D. In summary, the data suggest that in the presence of ATP one electron is transferred from flavodoxin hydroquinone via the [4Fe-4S]1+/2+ cluster of component A to Mo(VI) of component D, which is thereby reduced to Mo(V). The latter may supply the electron necessary for transient charge reversal in the unusual dehydration.

Adenosine Triphosphate↗

PubMed2002

Environmental exposure to trace elements and risk of amyotrophic lateral sclerosis: a population-based case-control study.

We analyzed the association between the environmental exposure to trace elements and the risk of sporadic amyotrophic lateral sclerosis (ALS) in a population-based case-control study in the Emilia-Romagna region in northern Italy. We evaluated exposure to selected trace elements by measuring toenail concentrations of the same by means of inductively coupled plasma optical spectrometry and instrumental neutron activation analysis. The final number enrolled in the study was 22 patients and 40 controls. Disease progression, assessed through a clinical score, was generally unassociated with toenail trace element levels, with the exception of an inverse relation with zinc and selenium content and a direct correlation with copper concentration. In logistic regression analysis, we found no evidence of an association between ALS risk and toenail content of cadmium, lead, copper, zinc, manganese, selenium, chromium, cobalt, iron, and aluminum. This investigation does not suggest a major role in sporadic ALS etiology of environmental exposure to these trace elements, though results for zinc, selenium, and copper should be evaluated with caution due to the potential limitations of toenails as biomarkers of chronic exposure in patients.

Amyotrophic Lateral Sclerosis↗