Trace elements and cardiovascular diseases.

The relation between trace elements and human health has been scarcely studied. With respect to cardiovascular diseases and hypertension attention has mostly focused on arsenic, cobalt, copper, chromium, fluorine, manganese, vanadium, zinc, selenium, silicon, cadmium, and lead. Environmental contamination can influence organ concentrations through long-term, low-level effects. This article reviews the present knowledge obtained by epidemiological, biochemical and cell biological studies. Attention is paid to interpretation problems due to the complexity of biochemical interactions with proteins of various sorts which determine metabolic processes and to the occurrence of detoxification mechanisms in which trace elements interact. This can also lead to strong variations in individual vulnerability. In general, the elements selenium, copper, zinc, chromium, and manganese seem to counteract the development of cardiovascular diseases, whereas cadmium and may be lead seem to stimulate it. Effects of arsenic, silicon and fluorine are unclear and for cobalt absent. The intensity of these effects on public health is difficult to measure, but is as yet probably limited except in extra-ordinary situations.

Prolonged low-level cadmium intake and atherosclerosis.

The frequencies of 10 diseases in a cadmium (and zinc) contaminated region in The Netherlands were analysed by comparing hospital admissions with those of a non-contaminated region and with national values. No significant differences were found for diseases which are commonly associated with increased cadmium uptake such as renal insufficiency, nephrolithiasis, hypertension, cancer, immaturity of the new-born. For the contaminated region a significantly higher frequency was only found for atherosclerosis; this was relatively strong for men aged > 40 yrs. However, no higher death frequency for atherosclerosis was observed. The results are discussed in relation to limitations in the evaluation techniques used. The absence of major health risks in the contaminated area is obvious, but the possible influence of long term-low level cadmium uptake on atherosclerosis requires more attention.

Trace-element concentrations in human autopsy tissue.

In this report on trace-element concentrations (As, Ca, Cd, Cl, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, Ni, Pb, Rb, Sb, Se, Zn) in human heart, liver, kidney, aorta, and rib obtained from 200 autopsied patients, we give special attention to sampling procedure, analysis technique, and various sources of error (autolysis, contamination with blood, and lack of sample homogeneity). We present the concentration data (averages, standard deviations, and ranges) obtained by neutron activation analysis, and we analyze the distribution of the data. The three types of distribution we distinguished are relevant to considerations of the importance of processes of storage of certain elements in specific organs.

Relationships between trace elements and atherosclerosis.

The possible relationship between trace element (Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Sb, Se, Zn) concentrations in various human tissues (heart, liver, kidney, aorta, rib and head hair) and cardiovascular diseases was studied on the basis of indications in the literature that trace elements may be directly or indirectly involved in cardiovascular disease processes. The underlying theme was that (slightly) reduced, as well as (slightly) elevated, concentrations compared with optimum values could, in the long term, lead to atherosclerotic lesions. In this project the tissues were obtained by autopsy involving 200 individuals (hospitalised patients and victims of traffic accidents). The seriousness of cardiovascular disease was quantitatively expressed by the degree of atherosclerosis of the descending branch of the left coronary artery (LAD) and of the abdominal aorta, for which a special measurement method was developed. Correlations were evaluated by two different methods, i.e. by a comparison of patients with extremely high or extremely low degrees of atherosclerosis and by means of stepwise multiple linear regression (SMLR) analysis. Corrections were made for the influence of age. The element Cd was found to be positively, and the elements Cu, Co, Se and Zn negatively, correlated with the degree of atherosclerosis. The inclusion of risk factors (diabetes mellitus, hypercholesterolaemia, hypertension, obesity and smoking) did not improve the explained variance.

Flow calorimetry of the sorption of butanols to elastin preparations and comparison with surface areas determined by krypton-85 adsorption.

1. The apparent surface areas of elastin samples as well as of several other fibrous protein preparations (collagen, keratin, polymeric stroma of aorta) were determined using two different approaches: (a) the Brunauer-Emmett-Teller method with 85Kr and (b) microflow calorimetry with n- and tert.-butanol as adsorbents in a heptane stream. 2. Areas of heat signals obtained by flow calorimetry for the adsorption and desorption of n- and tert.-butanol were substantially equivalent; desorption was more protracted than adsorption, the difference between the speed of desorption and adsorption increased with decreasing chain length of the alcohols (methanol, ethanol, n-propanol and n-butanol). 3. An inverse linear relationship was found between the energy change recorded during the adsorption process and the chain length of the alcohols (methanol, ethanol, n-propanol, n-butanol). 4. Heats of adsorption of tert.-butanol were systematically found to be significantly lower than those of n-butanol with all the protein samples investigated. 5. The apparent surface areas of the protein samples determined with tert.-butanol were on the average of the same order or only slightly higher than those obtained with 85Kr. Results obtained with n-butanol were significantly higher. The difference between surface areas obtained with n- and tert.-butanol depended on the nature of the protein sample, on its method of preparation and to some extent on the residual humidity of the sample. 6. The results could be explained on the basis of the hydrophobic theory of elastin structure (see ref. 4) and confirmed our former conclusions (see ref. 3) concerning the significantly higher surface areas of elastin samples purified by different procedures as compared to collagen or to keratin. They also confirmed the accessibility of the surface of elastic fibers to the molecular probes used in the polymeric stroma of aorta.