Aurora Kinase A is critical for the Nkx6.1 mediated ß-cell proliferation pathway.

Type 1 and type 2 diabetes are ultimately characterized by depleted ß-cell mass. Characterization of the molecular pathways that control ß-cell proliferation could be harnessed to restore these cells. The homeobox ß-cell transcription factor Nkx6.1 induces ß-cell proliferation by activating the orphan nuclear receptors Nr4a1 and Nr4a3. Here, we demonstrate that Nkx6.1 localizes to the promoter of the mitotic kinase AURKA (Aurora Kinase A) and induces its expression. Adenovirus mediated overexpression of AURKA is sufficient to induce proliferation in primary rat islets while maintaining glucose stimulated insulin secretion. Furthermore, AURKA is necessary for Nkx6.1 mediated ß-cell proliferation as demonstrated by shRNA mediated knock down and pharmacological inhibition of AURKA kinase activity. AURKA preferentially induces DNA replication in ß-cells as measured by BrdU incorporation, and enhances the rate of histone H3 phosphorylation in primary ß-cells, demonstrating that AURKA induces the replicative and mitotic cell cycle phases in rat ß-cells. Finally, overexpression of AURKA results in phosphorylation of the cell cycle regulator p53, which targets p53 for degradation and permits cell cycle progression. These studies define a pathway by which AURKA upregulation by Nkx6.1 results in phosphorylation and degradation of p53, thus removing a key inhibitory factor and permitting engagement of the ß-cell proliferation pathway.

Administration of recombinant factor VIIa decreases blood loss after blunt trauma in noncoagulopathic pigs.

BACKGROUND: Activated factor VII catalyzes the activation of clotting factors IX and X within the clotting cascade, and has been used clinically to decrease bleeding in patients with hemophilia and other bleeding disorders. Studies suggest the use of recombinant VIIa (rVIIa) may decrease bleeding after injury in the presence of a coagulopathy, but there is conflicting evidence regarding its use in the absence of coagulopathy. This study was performed to determine whether a single dose of rVIIa would reduce blood loss in noncoagulopathic pigs after blunt trauma. METHODS: Anesthetized pigs were subject to multiple blunt injuries consisting of a femur fracture, liver laceration, and soft-tissue crush injury. Fifteen minutes after the trauma, pigs were randomized to receive a single 120 microg/kg dose of rVIIa or placebo. Mean arterial pressure, heart rate, temperature, and hematocrit (Hct) were measured during a 2-hour period of standardized fluid resuscitation. The primary endpoint was blood loss. RESULTS: The degree of trauma in the two groups was similar. Animals in the treated group had a mean blood loss of 19.6 mL/kg (13.5-25.7) versus 30.0 mL/kg (24.8-35.3) in the control group (p = 0.037). CONCLUSIONS: A single dose of 120 microg/kg of rVIIa can significantly decrease blood loss in traumatized pigs with no preexisting coagulopathy. Further studies are required to determine the lowest effective dose of this medication.

Vitamin A activation of transforming growth factor-beta1 enhances porcine ileum wound healing in vitro.

Treatment with transforming growth factor-beta(1) (TGF-beta(1)) has been shown to be effective in accelerating skin wound healing. Another approach to gain the beneficial effects of TGF-beta(1) on wound healing could be the activation of tissue stores of latent TGF-beta(1) with agents such as vitamin A. The aims of this study were to determine whether 1) vitamin A is effective in enhancing intestinal wound healing in vitro and 2) activation of TGF-beta(1) is increased during wound healing with vitamin A treatment. We used the intraluminal chemical induction model of necrotizing enterocolitis (NEC), which was adapted to the 1-wk-old piglet. Injured (NEC) and noninjured full-thickness ileum explants harvested from the piglets were cultured for 24 and 48 h in serum-free medium supplemented with all-trans retinol (ATR; 0, 2, 5, and 10 microM). All concentrations of ATR improved recovery of normal ileal wall cytoarchitecture of NEC explants, with maximal recovery observed with 2 microM ATR after 24 h of culture. Further recovery after 48 h was observed with 5 and 10 microM ATR but did not achieve the degree of healing observed with 2 microM ATR. There were no observable adverse effects of ATR on noninjured ileal explant morphology. Active TGF-beta(1) was identified only in the NEC explants incubated with ATR. The results of this study demonstrate that administration of vitamin A accelerates recovery of normal intestinal wall cytoarchitecture of injured ileum in vitro, without adversely affecting noninjured ileum. The increased activation of latent TGF-beta(1) may, in part, be responsible for the accelerated healing of injured ileum observed with vitamin A administration.

Effect of lidocaine and epinephrine on Staphylococcus aureus in a guinea pig model of surgical wound infection.

Postoperative wound infection, most often with, is of ubiquitous concern in surgical practice, occurring in an average of 1.5 to 5 percent of all procedures. The antimicrobial properties of local anesthetics have been documented over the past 25 years by in vitro studies. This study evaluates the effects of lidocaine preparations on in an in vivo setting. In a wound infection model using live albino guinea pigs, inoculum was introduced for the reproducible bacterial colonization of clean surgical wounds. One of two sites on the dorsum of each animal was infiltrated with a commercial lidocaine preparation (with and without epinephrine) prior to inoculation with (10 cfu/ml). The other site, inoculated with without preinfiltration with lidocaine, served as the control. Cultures from the sites treated with lidocaine were then compared with cultures from the control sites. All control sites had a consistent presence >or=10 cfu/ml, the threshold for bacterial inhibition of wound healing. Infiltration of the wound with 2 ml of 2% lidocaine prior to inoculation was associated with an average decrease in bacterial count of >70 percent ( n= 19). On the other hand, the addition of epinephrine (1:100,000) to lidocaine was associated with a 20-fold in bacterial counts compared with control values ( n= 10). This is the first study to demonstrate inhibition of by a local anesthetic agent in an in vivo model of a surgical wound. This information suggests a possible role for local anesthetics in prophylaxis against surgical wound infection.