The Consequence of Ignoring a Level of Nesting in Multilevel Analysis: A Comment.

This short contribution is a comment on M. Moerbeek's exploration of consequences of ignoring a level of clustering in a multilevel model, which was published in the first issue of the 2004 volume of Multivariate Behavioral Research. After having recapitulated the framework and extended the results of Moerbeek's study, we formulate two critical notes.

Interaction between haemochromatosis and transferrin receptor genes in hepatocellular carcinoma.

In hepatocellular carcinoma (HCC) iron has been implicated as a risk factor primarily in patients with hereditary haemochromatosis (HH) and cirrhosis. The wild-type HH (HFE) protein complexes with the transferrin receptor (TFR), and two HFE mutations (Cys282Tyr and His63Asp) have been found to increase the affinity of the TFR for transferrin resulting in an increased cellular uptake of iron. In previous studies we found an interaction between HFE and TFR genotypes in multiple myeloma and breast and colorectal carcinomas.

Transferrin-mediated uptake of aluminium by human parathyroid cells results in reduced parathyroid hormone secretion.

Background: The present study investigates whether aluminium-transferrin (Al-Tf) uptake by Tf receptor-mediated endocytosis induces hypoparathyroidism and thus might contribute to the increasing prevalence of adynamic bone disease (ABD) in the current dialysis population.

Methods And Results: Human parathyroid glands as well as in vitro cultured human parathyroid cells were shown to express Tf receptors. Five-day-old cultures of parathyroid cells were incubated for 48 h in serum-free DMEM/F12 supplemented with 12 microM apo-Tf: 12 microM Tf to which 150 microg/l Al or 150 microg/l Al-citrate (Al-ci) was bound.

Manganese-containing superoxide dismutase signal sequence polymorphism associated with sporadic motor neuron disease.

An alanin-9valin (Ala-9Val) polymorphism in the mitochondrial targeting sequence of manganese-containing superoxide dismutase (Mn-SOD) has recently been described. We studied this polymorphism in 72 Swedish patients with sporadic motor neuron diseases (MND) and controls using an oligonucleotide ligation assay. There were significant differences in genotype between MND patients and controls (P = 0.

Ethnic variation in the mitochondrial targeting sequence polymorphism of MnSOD.

In contrast to CuZn superoxide dismutase (SOD), only a very limited number of mutations have been described in MnSOD. One interesting example is a polymorphism (Ala-9Val) in the mitochondrial targeting sequence of this radical-scavenging enzyme. We have studied the Ala-9Val polymorphism in various ethnic groups by means of the oligonucleotide ligation assay.