Evaluation of silver coated hemostatic dressing to control hemorrhage in a porcine model of lethal vascular injury.

THE AIM OF THE STUDY: An ideal hemostatic dressing that would control bleeding and protect the wound from further contamination is still being sought for combat casualty care. The new SilverLeaf™ (SL) bandage was made of material containing active hemostatic property and possible antimicrobial property from silver coating. This study was conducted to compare and ascertain the hemostatic properties of SL and compare it with known hemostatic dressings: Combat Gauze® (CG) and WoundStat™ (WS) in a swine model with punch, vascular injury. MATERIAL AND METHODS: Three hemostatic dressings were evaluated in anesthetized Yorkshire swine hemorrhaged for 45 sec in a femoral arterial puncture model. The hemostatic dressings SL, CG, or WS were applied on an actively bleeding wound, followed by 5 minutes of compression at 200 mm Hg. The pressure was then released to baseline and skin closed with towel clamps. After 15 minutes, 500 ml of (Hextend) resuscitation fluid infused over a period of 30 minutes. The animal's vital signs were monitored for the 3-hour experiment period. Primary outcomes documented were incidence of bleeding after application of the dressing, restoration of MAP and rate of survival.Results. The pre-treatment blood loss for WS was 375.66 ml (16.49%), SL 282.08 ml (12.15%) and CG 307.24 ml (12.68%) and was comparable between groups (p>0.56). The post-treatment blood loss for WS was 286.05 ml (10.65%), SL 386.81 ml (16.92%), and CG 525.76 ml (21.52%). There was no significant difference in post-treatment blood loss (p>0.37) between groups. The Mean Arterial Pressure (MAP) did not significantly differ between the groups at all time points compared. The SL and CG had comparable MAPS during the first hour. The SL had a slight advantage, but didn't reach statistical significance. This suggests that all the bandages were comparable. The two time points at which the post-treatment bleeding occurred in the three groups after the release of manual compression and after restoration of blood pressure. The post-treatment re-bleeding rates were 22.22% (2/9) for WS and SL, 44.44% (4/9) for CG. The survival rates were 100% for WS, 88.89% for SL, and 77.78% for CG. CONCLUSION: The findings indicate that SilverLeaf, WoundStat and Combat Gauze were comparable in controlling bleeding, preventing re-bleeding, maintenance of mean arterial pressure and improving survival following treatment.

cDNA cloning and gene expression analysis of human myo-inositol 1-phosphate synthase.

myo-Inositol 1-phosphate synthase (EC 5.5.1.4) (IPS) is a key enzyme in myo-inositol biosynthesis pathway. This study describes the molecular cloning of the full length human myo-inositol 1-phosphate synthase (hIPS) cDNA, tissue distribution of its mRNA and characterizes its gene expression in cultured HepG2 cells. Human testis, ovary, heart, placenta, and pancreas express relatively high level of hIPS mRNA, while blood leukocyte, thymus, skeletal muscle, and colon express low or marginal amount of the mRNA. In the presence of glucose, hIPS mRNA level increases 2- to 4-fold in HepG2 cells. hIPS mRNA is also up-regulated 2- to 3-fold by 2.5 microM lovastain. This up-regulation is prevented by mevalonic acid, farnesol, and geranylgeraniol, suggesting a G-protein mediated signal transduction mechanism in the regulation of hIPS gene expression. hIPS mRNA expression is 50% suppressed by 10mM lithium ion in these cells. Neither 5mM myo-inositol nor the three hormones: estrogen, thyroid hormone, and insulin altered hIPS mRNA expression in these cells.

IDH1 gene transcription is sterol regulated and activated by SREBP-1a and SREBP-2 in human hepatoma HepG2 cells: evidence that IDH1 may regulate lipogenesis in hepatic cells.

The mRNA level for cytosolic NADP-dependent isocitrate dehydrogenase (IDH1) increases 2.3-fold, and enzyme activity of NADP-isocitrate dehydrogenase (IDH) 63%, in sterol-deprived HepG2 cells. The mRNA levels of the NADP- and NAD-dependent mitochondrial enzymes show limited or lack of regulation under the same conditions. Nucleotide sequences that are required, and sufficient, for the sterol regulation of transcription are located within a 67 bp region of an IDH1-secreted alkaline phosphatase promoter-reporter gene. The IDH1 promoter is fully activated by the expression of SREBP-1a in the cells and, to a lesser degree, by that of SREBP-2. A 5'-end truncation of 23 bp containing a CAAT and a GC-Box results in 6.5% residual activity. The promoter region involved in the activation by the sterol regulatory element binding proteins (SREBPs) is located at nucleotides -44 to -25. Mutagenesis analysis identified within this region the IDH1-SRE sequence element GTGGGCTGAG, which binds the SREBPs. Similar to the promoter activation, electrophoretic mobility shifts of probes containing the IDH1-SRE element exhibit preferential binding to SREBP-1a, as compared with SREBP-2. These results indicate that IDH1 activity is coordinately regulated with the cholesterol and fatty acid biosynthetic pathways and suggest that it is the source for the cytosolic NADPH required by these pathways.

Low-temperature effect on the sterol-dependent processing of SREBPs and transcription of related genes in HepG2 cells.

Lowering the growth temperature of HepG2 cells from 37 degrees C to 20 degrees C results in a 73% reduction in human squalene synthase (HSS) protein, a 76% reduction in HSS mRNA, and a 96% reduction in promoter activity of a secreted alkaline phosphatase-HSS reporter gene. A similar decrease in either mRNA or protein levels is observed for 3-hydroxy-3-methylglutaryl CoA reductase, farnesyl diphosphate synthase, the LDL receptor, and fatty acid synthase. All these proteins and mRNAs show either a decrease or a complete loss of sterol-dependent regulation in cells grown at 20 degrees C. In contrast, sterol regulatory element binding proteins (SREBPs)-1 and -2 exhibit a 2- to 3-fold increase in mRNA levels at 20 degrees C. The membrane-bound form of the SREBPs is dramatically increased, but the proteolytic processing to the nuclear (N-SREBP) form is inhibited under these conditions. Overexpression of the N-SREBP or SREBP cleavage-activating protein (SCAP), but not site-1 or site-2 proteases, restores the activation of the HSS promoter at 20 degrees C, most likely by liberating the SCAP-SREBP complex so that it can move to the Golgi for processing. These results indicate that the cholesterol synthesizing machinery is down-regulated at low temperatures, and points to the transport of the SCAP-SREBP complex to the Golgi as the specific down-regulated step.