Hepatic iron deposition does not predict extrahepatic iron loading in mouse models of hereditary hemochromatosis.

Hereditary hemochromatosis is characterized by tissue iron loading and associated organ damage. However, the phenotype can be highly variable. The relationship between iron loading of different organs and the temporal nature of its deposition is still not well understood. We examined the progression of tissue iron loading in three mouse models to advance our understanding of the natural history of iron deposition in hereditary hemochromatosis. Wild-type, Hfe(-/-), Tfr2(-/-), and Hfe(-/-)/Tfr2(-/-) mice were analyzed at 3, 5, 10, 26, and 52 weeks, respectively. Hepatic, splenic, cardiac, and pancreatic iron concentrations were determined. Expression of both iron-regulatory and fibrosis genes was determined by quantitative real-time PCR in livers and hearts of 52-week-old mice. In all models, hepatic iron increased rapidly, plateauing before 10 weeks at different levels, depending on the genotype. Iron deposition in the pancreas and heart occurred after maximal iron loading of the liver was reached and was most marked in the Hfe(-/-)/Tfr2(-/-) mice. Although a significant positive correlation was identified between pancreatic and cardiac iron in all models at 52 weeks, there was no correlation between hepatic and either pancreatic or cardiac iron. There is variability in the timing and extent of tissue iron loading within a genotype, suggesting that hepatic iron levels in hereditary hemochromatosis may not accurately predict the iron content of other organs.

G2/M checkpoint gene expression in developing germ cells.

Cell cycle progression is prevented by signal transduction pathways known as checkpoints which are activated in response to replication interference and DNA damage. We cloned a G2/M cell cycle phase-related checkpoint gene from a neonatal mouse testis cDNA library which was identified as mouse claspin, a proposed adaptor protein for Chk1. As part of a study on germ cell differentiation we examined the expression of the checkpoint gene, Chk1, and claspin at 12.5 and 14.5 days post coitum (dpc) and in the post-natal phase. Chk1 mRNA expression increased from 12.5 to 14.5 dpc in female gonads and was strong in males at both time points. Claspin however, was not detected until 14.5 dpc. This suggests there may be some dissociation of claspin expression from Chk1 in fetal germ cell development. Chk1 and claspin expression was also studied in testis over the first 3 days following birth, when apoptosis regulates germ stem cell number. We modulated checkpoint-related gene expression in testis using the anti-metabolite, 5-fluorouracil, resulting in increased apoptosis and upregulation of Chk1 (P<0.0001) and Cdc2 (P<0.02) mRNA. Although we do not fully understand the role checkpoint gene expression has during mammalian germ cell development this report is the first to show the expression of checkpoint-related genes in early mammalian germ cells.

A comparison of wound healing following treatment with Lavandula x allardii honey or essential oil.

The increased interest in complementary therapies has led to the investigation of products traditionally believed to have a beneficial effect in wound healing. Two such products are honey and lavender essential oil. In this study a rat excisional wound model was used to investigate the action of Lavandula x allardii honey and essential oil, and a standard therapeutic honey (Medihoney). Four 8 mm wounds were created surgically on the dorsal surface of each rat and honey or essential oil applied to the wounds twice a day for 4 days. Wound healing was analysed by wound contraction and capillary volume at 5 and 12 days post-surgery. Although no statistically significant difference in wound contraction was observed for the essential oil or honey treated wounds relative to the untreated control, both honeys were shown to reduce the capillary volume in the wound site at day 12 with no difference between the honeys (control 154 +/- 14 microm(3) vs L. x allardii honey 77 +/- 18 microm(3) and Medihoney 89 +/- 39 microm(3), p < 0.001; mean +/- SD). This suggests that scar maturation in these animals was more advanced than in other groups. These data suggest that L. x allardii honey, but not essential oil, has a beneficial action in wound healing.

Bactericidal activity of different honeys against pathogenic bacteria.

BACKGROUND: Renewed interest in honey for various therapeutic purposes including treatment of infected wounds has led to the search for new antibacterial honeys. In this study we have assessed the antibacterial activity of three locally produced honeys and compared them to three commercial therapeutic honeys (including Medihoney and manuka honey). METHODS: An agar dilution method was used to assess the activity of honeys against 13 bacteria and one yeast. The honeys were tested at five concentrations ranging from 0.1 to 20%. RESULTS: Twelve of the 13 bacteria were inhibited by all honeys used in this study with only Serratia marcescens and the yeast Candida albicans not inhibited by the honeys. Little or no antibacterial activity was seen at honey concentrations <1%, with minimal inhibition at 5%. No honey was able to produce complete inhibition of bacterial growth. Although Medihoney and manuka had the overall best activity, the locally produced honeys had equivalent inhibitory activity for some, but not all, bacteria. CONCLUSIONS: Honeys other than those commercially available as antibacterial honeys can have equivalent antibacterial activity. These newly identified antibacterial honeys may prove to be a valuable source of future therapeutic honeys.

Prohepcidin localises to the Golgi compartment and secretory pathway in hepatocytes.

BACKGROUND/AIMS: Hepcidin is a liver-expressed peptide which plays an important role in the regulation of iron metabolism. It is a negative regulator of iron absorption and release of iron from cells. The aims of this study were to analyse the expression and localisation of prohepcidin in liver and cell lines. METHODS: We generated antibodies against recombinant mouse prohepcidin and studied its expression in cell lines, primary hepatocytes and livers of normal mice and mice with abnormalities in iron metabolism. RESULTS: Prohepcidin localised to the secretory pathway, primarily the Golgi apparatus in liver cells and tissues. Hfe and beta2-microglobulin knockout mice have similar levels of prohepcidin protein expression as compared to wild-type mice despite increased iron stores. Sex-linked anaemia mice have iron deficiency and no prohepcidin expression in the liver. CONCLUSIONS: Prohepcidin protein is present in the secretory pathway of liver cells. Despite iron loading, mouse models of haemochromatosis have comparatively normal levels of prohepcidin expression whereas mice with iron deficiency have no prohepcidin expression.