Effect of polyurethane chemistry and protein coating on monocyte differentiation towards a wound healing phenotype macrophage

Tissue regeneration alternatives for peripheral vascular disease are actively being investigated; however, few studies in this area have probed the role of the wound healing monocyte-derived macrophage (MDM). Inflammatory MDMs transition to wound healing MDMs as the relative levels of tumor necrosis factor-alpha (TNF-α) decrease and IL-10 increase. TNF-α has been linked to the regulation of HMGB1 (high mobility group box 1 protein), a nuclear protein that upon macrophage stimulation can be secreted and act as a pro-inflammatory cytokine. This study investigated the influence of a degradable polar hydrophobic ionic polyurethane (D-PHI) on MDM cell expression of pro- versus anti-inflammatory markers, when the material was uncoated or pre-coated with collagen prior to cell studies. Effects were compared to similar groups on tissue culture polystyrene (TCPS). Collagen coated TCPS and D-PHI had significantly more DNA than the uncoated TCPS after 7d (p = 0.001 and p = 0.006 respectively); however, there was significantly less esterase activity from cells on D-PHI (±collagen) than for cells on TCPS after 7d (p = 0.002, p = 0.0003 respectively). No significant differences in esterase activity were observed between collagen coated and non-coated D-PHI surfaces. Analyses of pro-inflammatory cytokines (TNF-α, IL-1β and HMGB1) secreted from differentiating monocytes adherent to D-PHI demonstrated a decrease whereas anti-inflammatory IL-10 increased over time when compared to TCPS, suggesting that D-PHI was less inflammatory than TCPS. Since D-PHI maintains cell attachment while aiding in the transition of MDM to a wound healing phenotype, this material has qualities suitable to be used in tissue engineering applications where MDM play a key role in tissue regeneration.     

The effects of hypervitaminosis A in sheep following intramuscular administrations of vitamin A

Ten ewe lambs (median age 11 months and average weight 29.2 ± 2.5 kg) were used in the present study. They were divided into two groups: test (n = 5) and control (n = 5). Housing and all diets were identical. In the test group vitamin A was injected into the thigh muscle at a daily dose of 5000 IU/kg body weight for 16 days. The average final body weight of sheep in the test group was significantly (P < 0.05) less than the control group.     

Luteolin and thiosalicylate inhibit HgCl(2) and thimerosal-induced VEGF release from human mast cells

HgCl2 is a known environemental neurotoxin, but is also used as preservative in vaccines as thimerosal containing ethyl mercury covalently linked to thiosalicylate. We recently reported that mercury choloride (HgCl(2)) can stimulate human mast cells to release vascular endothelial growth factor (VEGF), which is also vasoactive and pro-inflammatory. Here we show that thimerosal induces significant VEGF release from human leukemic cultured LAD2 mast cells (at 1 microM 326 ± 12 pg/106 cells and 335.5 ± 12 pg/106 cells at 10 microM) compared to control cells (242 ± 21 pg/106 cells, n=5, p less than 0.05); this effect is weaker than that induced by HgCl2 at 10 microM (448 ± 14 pg/106 cells) (n=3, p less than 0.05). In view of this finding, we hypothesize that the thiosalicylate component of thimerosal may have an inhibitory effect on VEGF release. Thimerosal (10 microM) added together with the peptide Substance P (SP) at 2 microM, used as a positive control, reduced VEGF release by 90 percent. Methyl thiosalicylate (1 or 10 microM) added with either SP or HgCl2 (10 microM) inhibited VEGF release by 100 percent, while sodium salicylate or ibuprofen had no effect. Pretreatment for 10 min with the flavonoid luteolin (0.1 mM) before HgCl2 or thimerosal compeletly blocked their effect. Luteolin and methyl thiosalicylate may be useful in preventing mercury-induced toxicity.     

Role of ATP-sensitive potassium channels in the biphasic effects of morphine on pentylenetetrazole-induced seizure threshold in mice

Although several studies have indicated that the opioid receptor agonist morphine exerts biphasic effects on clonic seizure threshold, as yet little is known of the underlying mechanisms in this effect. In the present study, using the specific ATP-sensitive K(+) (K(ATP)) channel blocker glibenclamide and the specific K(ATP) channel opener cromakalim, the possible involvement of K(ATP) channels in the effects of morphine on pentylenetetrazole (PTZ)-induced seizure threshold in mice was investigated. Acute administration of lower doses of morphine (1, 3 and 7.5 mg/kg, i.p.) increased and higher doses of morphine (30 and 60 mg/kg, i.p.) decreased the PTZ-induced seizure threshold. Glibenclamide (2.5-5 mg/kg) increased the PTZ-induced seizure threshold. Non-effective dose of cromakalim (0.1 microg/kg) inhibited anticonvulsant effect of glibenclamide (5 mg/kg). Acute administration of non-effective dose of glibenclamide (1 mg/kg) interestingly inhibited both anticonvulsant and pro-convulsant effects of morphine and this effect was significantly reversed by cromakalim (0.1 microg/kg). These results support the involvement of K(ATP) channels in the modulation of seizure threshold by morphine.     

Mercury induces inflammatory mediator release from human mast cells

Background  

Mercury is known to be neurotoxic, but its effects on the immune system are less well known. Mast cells are involved in allergic reactions, but also in innate and acquired immunity, as well as in inflammation. Many patients with Autism Spectrum Disorders (ASD) have "allergic" symptoms; moreover, the prevalence of ASD in patients with mastocytosis, characterized by numerous hyperactive mast cells in most tissues, is 10-fold higher than the general population suggesting mast cell involvement. We, therefore, investigated the effect of mercuric chloride (HgCl₂) on human mast cell activation.