Iron up-modulates the expression of transferrin receptors during monocyte-macrophage maturation

Abstract We have investigated the effect of iron on the expression of transferrin receptors (TrfRs) and ferritin chains in cultures of human peripheral blood monocytes maturing to macrophages. Monocyte-macrophage maturation is associated with a gradual rise of Trf-binding capacity in the absence of cell proliferation. At all culture times, treatment with ferric ammonium citrate induces a dose-dependent rise of the Trf-binding level as compared with nontreated cells. Scatchard analysis revealed that this phenomenon is due to an increase in receptor number rather than an alteration in ligand-receptor affinity. Biosynthesis experiments indicated that the rise in number of TrfRs is due to an increase of receptor synthesis, which is associated with a sustained elevation of the TrfR RNA level. The up-regulation of TrfR synthesis is specific in that expression of other macrophage membrane proteins is not affected by iron addition. Conversely, addition of an iron chelator induced a slight decrease of TrfR synthesis. The expression of heavy and light ferritin chains at RNA and protein levels was markedly more elevated in cultured macrophages than in fresh monocytes, thus suggesting modulation of ferritin genes at transcriptional or post-transcriptional levels. Addition of iron salts to monocyte-macrophage cultures sharply stimulated ferritin synthesis but only slightly enhanced the level of ferritin RNA, thus indicating a modulation at the translational level. These results suggests that in cultured human monocytes-macrophages, iron up-regulates TrfR expression, thus in sharp contrast to the negative feedback reported in a variety of other cell types. These observations may shed light on the mechanism(s) of iron storage in tissue macrophages under normal conditions and possibly on the pathogenesis of diseases characterized by abnormal iron storage

An evaluation of the effects of the smoking ban at an acute NHS trust

The purpose of this study was to explore the effects of a complete smoking ban at an NHS Trust focusing on the attitudes, compliance and smoking behaviour of NHS Staff on the smoke-free NHS policy. Questionnaires were distributed to staff 17 months after the Trust implemented its smoking ban and two months before the nationwide smoking ban. Although the study showed that a significant proportion of respondents were in favour of the ban (78.3%), results also suggested that many staff felt that designated areas should be provided for those who smoked. Positive staff attitudes towards the ban did not seem to affect actual behaviour as staff continued to smoke on hospital grounds. This study suggests that more work is needed to enforce the smoke-free policy and increase awareness of workplace smoking cessation interventions in order to change smoking behaviour in this workplace

Superior Mesenteric Artery Syndrome-Believe in It! Report of a Case

We present a case of a man with amyotrophic lateral sclerosis who developed superior mesenteric artery syndrome (SMAS) following the confection of feeding jejunostomy. He was successfully managed by conservative treatment. Left lateral positioning during enteral feeding allowed quick resolution of the occlusive state. Various surgical interventions have been associated with SMAS, directly or indirectly, by reducing the width of the aortomesenteric angle. The operative stress was probably what triggered symptomatology in our patient thus to conclude that the surgical stress should be considered as a causal factor triggering the SMAS in a context of other predisposing factors