Elements in autopsy liver tissue samples from Greenlandic Inuit and Danes. III. Zinc measured by X-ray fluorescence spectrometry

The association between content of the elements S, Cl, K, Fe, Cu, Zn and Br in normal and cirrhotic liver tissue from Danes and Greenlandic Inuit examined by dual hierarchical clustering analysis

PROJECT

Meta-analysis of previous studies evaluating associations between content of elements sulphur (S), chlorine (Cl), potassium (K), iron (Fe), copper (Cu), zinc (Zn) and bromine (Br) in normal and cirrhotic autopsy liver tissue samples.

PROCEDURE

Normal liver samples from 45 Greenlandic Inuit, median age 60 years and from 71 Danes, median age 61 years. Cirrhotic liver samples from 27 Danes, median age 71 years. Element content was measured using X-ray fluorescence spectrometry.

STATISTICS

Dual hierarchical clustering analysis, creating a dual dendrogram, one clustering element contents according to calculated similarities, one clustering elements according to correlation coefficients between the element contents, both using Euclidian distance and Ward Procedure.

RESULTS

One dendrogram separated subjects in 7 clusters showing no differences in ethnicity, gender or age. The analysis discriminated between elements in normal and cirrhotic livers. The other dendrogram clustered elements in four clusters: sulphur and chlorine; copper and bromine; potassium and zinc; iron. There were significant correlations between the elements in normal liver samples: S was associated with Cl, K, Br and Zn; Cl with S and Br; K with S, Br and Zn; Cu with Br. Zn with S and K. Br with S, Cl, K and Cu. Fe did not show significant associations with any other element.

CONCLUSIONS

In contrast to simple statistical methods, which analyses content of elements separately one by one, dual hierarchical clustering analysis incorporates all elements at the same time and can be used to examine the linkage and interplay between multiple elements in tissue samples.

Rubidium content in autopsy liver tissue samples from Greenlandic Inuit and Danes measured by X-ray fluorescence spectrometry

BACKGROUND

The biological function of rubidium (Rb) is unknown, but this alkali metal probably has a normal biologic role.

OBJECTIVE

To measure the content of Rb in liver tissue samples from Greenlandic Inuit using X-ray fluorescence spectrometry, and compare the results with those obtained in liver samples from ethnic Danes.

STUDY DESIGN

Observational, descriptive survey on environmental pathology.

METHODS

The setting was related to forensic medicine and hospitalised care in Nuuk, Ilulissat and Copenhagen. Normal liver tissue was obtained at autopsy from 50 Greenlandic Inuit (27 men) with a median age of 61 years (range 23-83) and from 42 Danes (31 men) with a median age of 38 years (range 16-83).

RESULTS

Liver Rb content in Inuit was not significantly different compared with Danes. There was no significant gender difference in liver Rb content either in Inuit or in Danes. The content of Rb given as median (5-95 percentile) was 0.1837mmol/kg dry liver (0.1041-0.3147) in Inuit, and 0.1965mmol/kg dry liver (0.0799-0.2815) in Danes (p=0.6). There was an inverse correlation between liver Rb content and age in Inuit (r(s)=-0.45, p=0.002) but not in Danes. Median hepatic Rb index (Rb content in micromol/kg dry weight divided by age in years) in Inuit was 3.05 and in Danes 4.21 (p=0.02). The correlations between liver Rb and liver potassium content were: Inuit r(s)=0.28, p=0.07; Danes r(s)=0.25, p=0.08; combined series r(s)=0.34, p=0.01.

CONCLUSIONS

Inuit have liver Rb levels, which are quite similar to the levels found in Danes. In Inuit, liver Rb content appears to decrease with age.