[Show abstract][Hide abstract] ABSTRACT: Diabetics have an increased risk of developing cardiovascular disease, in part due to oxidative stress, resulting in endothelial nitric oxide synthase (eNOS) dysfunction. Studies have demonstrated that angiotensin-(1-7) [Ang-(1-7)] can activate eNOS activity. Because the bone marrow is a primary source of a number of progenitors important in physiological homeostasis and healing, the goal of this study was to evaluate the in vivo effects of Ang-(1-7) treatment on oxidative stress and the ensuing nitrative stress in diabetic bone marrow and its potential pathways. BKS.Cg-Dock7(m) +/+ Lepr(db)/J mice and their heterozygous controls were administered Ang-(1-7) alone or combined with A-779, losartan, PD123,319, nitro-l-arginine methyl ester, or icatibant sc for 14 d. The bone marrow was then collected to measure nitric oxide levels, eNOS phosphorylation, and expression of nitric oxide synthase, superoxide dismutase, and p22-phox. Nitric oxide levels in the bone marrow were significantly decreased in diabetic mice, and Ang-(1-7) treatment was able to significantly increase these measures (P < 0.01). This effect was blocked by the coadministration of PD123,319, A-779, nitro-l-arginine methyl ester, and icatibant. In addition, Ang-(1-7) treatment reversed the paradoxical increase in eNOS and neuronal nitric oxide synthase expression and decreased the phosphorylation of eNOS at Thr495 seen in diabetic mice. Ang-(1-7) also reversed diabetes-induced production of reactive oxygen species by decreasing p22-phox expression and increasing superoxide dismutase 3 expression, leading to a significant reduction in 3-nitrotyrosine formation in diabetic bone marrow (P < 0.05). Our findings demonstrate that Ang-(1-7) administration decreases diabetes-induced oxidative stress in the bone marrow and modifies pathways involved in eNOS dysfunction.
[Show abstract][Hide abstract] ABSTRACT: The renin angiotensin system (RAS) has been shown to be present in dermal tissue and exogenous peptides from the RAS accelerates healing and reduces scarring. An analogue of Angiotensin(1–7) [A(1–7)], Norleucine3-A(1–7) [Nle3-A(1–7)], is the lead compound under development for treatment of dermal injuries. As proteases are prevalent in wounded tissue and at very high levels in chronic wounds, the ability of fragments of Nle3-A(1–7) to accelerate healing and the effect of proteases on the peptide were determined. Daily application of fragments of Nle3-A(1–7) of five or six amino acids accelerated healing in two models of dermal injury. In addition, the peptide was found to be stable (not substantially degraded) after incubation for 4 h in the presence of Cathepsin G, collagenases blend (from clostridium), matrix metalloprotease [MMP] 2, MMP 3, MMP 9, elastase (human leukocytic or porcine pancreatic) or plasmin. Only kallikrein, an enzyme known to cleave peptides of the RAS, cleaved the peptide into two major fragments one of which was identified as NorLeu3-A(1–4). These data support the activity of Nle3-A(1–7) on dermal wounds.
European Journal of Allergy and Clinical Immunology 10/2008; 66(s1):41 - 47. · 1.30 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Peri-operative lavage and postoperative instillation of a 4% icodextrin solution reduces de novo formation and reformation of peritoneal adhesions following abdominal surgery. This experimental study evaluated the effects of 4% icodextrin treatment on the healing of bowel anastomoses and laparotomy incisions.
Female New Zealand White rabbits (weight 2.21-2.77 kg) were randomised by ascending weight to one of 3 surgical treatments, each with 2 termination points (6 groups of 8 animals). The treatments were anastomotic bowel surgery alone or with lavage and postoperative instillation of either 4% icodextrin solution or Lactated Ringer's Solution (LRS). The solutions were coded A and B by the supplier, so that the study personnel were blinded to their identity. After the abdomen was opened, 30 ml of solution A or B was instilled and removed by aspiration prior to surgery. The ascending colon was then transected 5 cm aboral to the ileocaecal junction and the ends anastomosed. During surgery, 5 ml of the solution was applied 4 times at the surgical site, and a further 30 ml was administered and aspirated as a postoperative lavage. Just prior to closure of the abdominal wall, 50 ml of the solution was administered as a postoperative instillate. Duplicate treatment groups were terminated 7 and 21 days after surgery and the anastomotic sites inspected for adhesion and/or abscess formation. In 6 animals per group, an 8-12 cm length of colon including the anastomotic site was removed for measurement of bursting pressure, and a section of the abdominal wall including the incision line was tested for breaking strength. The other 2 animals per group provided tissue for histological analysis of wound healing at the bowel and incision sites.
There was no significant difference between the 3 treatment groups for any parameter (P > 0.05). Compared with the surgical control at either day 7 or 21 after surgery, the administration of solutions A or B did not affect the formation of abscesses or adhesions, the bursting strength of the bowel, or the tear strength of the abdominal wall incision. Histological assessment of the quality of wound healing showed no differences between treatment groups in inflammatory cell infiltration, fibroblast density, blood vessel formation or collagen maturity.
The use of a 4% icodextrin solution for peri-operative lavage and postoperative instillation in a rabbit model of bowel anastomotic healing did not result in any difference from either LRS treated or untreated surgical controls.
[Show abstract][Hide abstract] ABSTRACT: Adhesion formation is a significant source of postoperative morbidity. Current barrier products on the market in the United States are difficult to use during a laparoscopic procedure or over irregular surfaces. The efficacy of a sprayable adhesion prevention barrier, CoStop, was evaluated in three separate rabbit adhesion models. In an initial study, the effect of CoStop and Seprafilm bioresorbable membrane was evaluated in a rabbit uterine horn abrasion model. At necropsy, 67% of the CoStop-treated rabbits and 61% of the Seprafilm-treated animals were adhesion free. In a rabbit sidewall adhesion formation model, 90% of rabbits treated with CoStop were free of adhesions at necropsy, whereas all surgical controls formed adhesions. A comparable level of efficacy was observed in a rabbit re-formation model in which adhesions were generated and lysed 1 week later. After adhesiolysis, all control rabbits re-formed adhesions over 95% of the area. In contrast, 67% of the CoStop- and 38% of the Seprafilm-treated rabbits were adhesion free. Histological evaluation performed on tissues from the studies indicates that the CoStop barrier is biocompatible in all three surgical situations. CoStop-treated animals in all adhesion models showed a significant reduction in the incidence, extent, and severity of adhesion formation.
Obstetrics and Gynecology 01/2001; 97(4):S19. · 4.80 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Intra-abdominal adhesion formation causes significant post-operative morbidity. Controlled studies using animal models have been carried out to assess the tolerability and preventive efficacy of icodextrin solution (a biodegradable, biocompatible, glucose polymer). Reduction of adhesion formation was first evaluated in a rabbit double uterine horn model, applying 10-75 ml of 7.5 and 20%, or 50 ml of 2.5-20% icodextrin solution post-operatively. Significant increases in adhesion free sites (P < 0.005) were observed with volumes > or =25 ml, and at concentrations > or =4%. Efficacy of 50 ml 4 and 20% icodextrin was then evaluated both during and after surgery, demonstrating significant reductions in adhesion formation (P < 0. 002). In one study, intra- plus post-operative use of 4% icodextrin produced the greatest reduction of non-surgical site adhesions; in others, the post-operative effect was predominant. Post-surgical administration of 50 ml 4% icodextrin in a rabbit sidewall model also resulted in more adhesion-free animals, and a significant reduction (P < 0.001) in areas of adhesion formation and reformation. In a rat infection potentiation model, 4% icodextrin produced no difference in mortality, abscess formation or overall abscess score. These data suggest that 4% icodextrin offers a well-tolerated and effective means of reducing post-surgical adhesion formation.
Human Reproduction 08/2000; 15(8):1764-72. · 4.67 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: OBJECTIVE: To assess the efficacy of Oxiplex (FzioMed, Inc., San Luis Obispo, CA) barriers. DESIGN: Film of polyethylene oxide and carboxymethylcellulose (Oxiplex) were tested for strength and tissue adherence. Films were selected for evaluation in models for biocompatability and adherence. Three films were selected for evaluation in efficacy studies, and one was evaluated for effects on bacterial peritonitis. Handling characteristics of Oxiplex film were evaluated via laparoscopy. SETTING: University laboratory. PATIENT(s): Rabbits, rats, pigs.Intervention(s): Placement of Oxiplex prototypes at the site of injury. MAIN OUTCOME MEASURE(s): Mechanical properties, biocompatibility, tissue adherence, adhesion development, infection potentiation, and device handling. RESULT(s): Mechanical tests indicated that tensile strength and elongation were inversely correlated. All films tested had excellent tissue adherence properties. Selected films, based on residence time and biocompatibility, prevented adhesion formation in all animals and were highly efficacious in preventing adhesion reformation. The optimal Oxiplex prototype prevented adhesion reformation in 91% of the animals. This Oxiplex film, dyed to allow visualization, prevented adhesion reformation and did not affect bacterial peritonitis. In a laparoscopic model, the Oxiplex film, delivered in FilmSert forceps, via a 5.0-mm trocar, rapidly unfurled and could be easily applied to tissue with strong adherence. CONCLUSION(s): These data show development of an adhesion prevention material that is tissue adherent, can be placed via laparoscopy, and does not affect host resistance.
Fertility and Sterility 05/2000; 73(4):831-8. · 4.17 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Angiotensin II (AII) induced the proliferation of hematopoietic progenitor cells (HPC) isolated from murine bone marrow or human cord blood. The formation of colonies with more than 50 cells increased approximately five-sevenfold in cultures of murine lineage-negative (Lin(-)) bone marrow cells both in the presence (day 10) and absence (day 13) of colony-stimulating factors (CSF). This could be blocked with addition of Losartan, an antagonist of AIITR1. The increase in proliferation of early hematopoietic progenitors (Lin(-)Sca l(+) cells) by AII was approximately threefold and occurred only in the presence of CSF, suggesting that AII may affect mesenchymal stromal cells to induce CSF production and might directly affect early HPC. These in vitro studies were replicated with human HPC isolated from cord blood. AII also accelerated the proliferation and formation of colony-forming units (CFU)-granulocyte/erythroid/macrophage/megakaryocyte and CFU-granulocyte/macrophage colonies by CD34(+)CD38(-) enriched progenitors but only in the presence of CSF. Additional studies also indicated that AII can act to increase proliferation in suspension culture. Exposure of CD34(+) cells to AII in suspension culture, prior to placement in a semisolid medium with erythropoietin, increased the formation of colonies with more than 50 cells and erythroid progenitors approximately five- and 20-fold, respectively. Further, mRNA for the AT1a receptor was expressed by human bone marrow CD34(+)CD38(-) cells, CD34(+)CD38(-) cells, and lymphocytes, but not mature myeloid cells. Similarly, mRNA for the AT1a receptor was expressed on human stromal cell clones, offering further support to the hypothesis that AII acts partially through the mesenchymal compartment of the bone marrow. These data suggest that AII may be a factor which stimulates the proliferation of hematopoietic progenitors.
[Show abstract][Hide abstract] ABSTRACT: The formation of postoperative cardiac adhesions makes a repeat sternotomy time consuming and dangerous. Many attempts have been made to solve this problem by using either drugs to inhibit fibrinolytic activity or different types of pericardial substitutes. The results have not been satisfactory.
The efficacy of bioresorbable film prototypes made of polyethylene glycol (EO) and polylactic acid (LA) (EO/LA = 1.5, 2.5, and 3.0) in the prevention of adhesions after cardiac operations in canine models was tested. After desiccation and abrasion of the epicardium, a transparent bioresorbable film was placed over the heart. The pericardium was closed to allow intrapericardial adhesions (n = 32) or left open and attached to the chest wall to induce retrosternal adhesions (n = 17). Postoperative recovery was similar among the groups. Retrosternal and pericardial adhesions were evaluated at necropsy 3 weeks later by assessing area, tenacity, and density of the adhesions.
In the control dogs, tenacious, dense adhesions were observed. In contrast, adhesion formation was reduced at all sites covered by the films. The bioresorbable films were efficacious in the reduction of adhesion formation between epicardium and pericardium or between epicardium and sternum after cardiac operation. The EO/LA 1.5 film most effectively prevented the early adhesions.
The bioresorbable films (EO/LA = 1.5, 2.5, and 3.0) significantly reduced adhesion formation, with EO/LA = 1.5 (Repel CV) being optimal. As the barrier was rapidly resorbed, the capsule formation induced by permanent barriers was avoided.
The Annals of Thoracic Surgery 10/1999; 68(3):913-8. · 3.45 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To evaluate the ability of a variety of peptides containing the Arg-Gly-Asp (RGD) sequence to reduce the formation of intraperitoneal adhesions in a rabbit model.
Prospective, randomized, double-blinded study.
New Zealand white rabbits.
Administration of RGD-containing peptides.
Reduction of adhesion information.
In initial studies, two RGD-containing peptides (3 or a 10 amino acid peptides) were administered via Alzet miniosmotic pump to the site of injury. Administration of either of these peptides significantly reduced adhesion formation, but the larger peptide was more efficacious and reduced variability in the response. Further studies then were conducted with RGD-containing peptides five to six amino acids in length. Administration of these peptides also significantly reduced adhesion formation in a standard rabbit model. Administration of three of these peptides in a viscous vehicle at the end of surgery was also effective in reducing adhesion formation.
The most effective combination tested was RGD-containing peptide Gly-dser-Arg-Gly-Asp-Ser-Pro in a viscous, cremophor-containing vehicle. These studies demonstrate that administration of an RGD-containing peptide was effective in reducing adhesion formation in this model.
Fertility and Sterility 01/1999; 70(6):1131-8. · 4.17 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Adhesion formation is a major source of postoperative morbidity and mortality. In this study, the ability of a variety of lazaroid formulations [the antioxidant 21-aminosteroid PNU74006F (tirilazad) and the non-steroidal 2-methylaminochroman derivative PNU83,836E] to reduce i.p. adhesion formation in three rabbit models was examined. In initial studies, PNU83836E was administered via Alzet miniosmotic pump to the site of injury. In the sidewall and double uterine horn models, PNU83,836E was administered via Alzet miniosmotic pump for the entire postoperative interval. In the sidewall model, there was a dose-dependent reduction in the area of the sidewall injury that was involved in adhesions. In the double uterine horn model, PNU83,836E was administered via Alzet miniosmotic pump to the area of injury for 1, 2, 3 or 7 days. Administration for as little as 24 h after surgery significantly reduced the extent of adhesion formation and the reduction was increased if it was administered for longer. Further studies were conducted in which various lazaroid formulations were administered as a bolus at the end of surgery. In both the sidewall and double uterine horn models, administration of either PNU83,386E (in citrate buffer) or PNU74006F (in cyclodextrin or lipid emulsion vehicles) at the end of surgery reduced adhesion formation. Administration of a bolus of PNU74006F 10 min prior to initiation of surgery with or without additional treatment at the end of surgery further increased its efficacy in the reduction of adhesion formation. Administration of a minimum of 1.5 mg before and after surgery (3 mg total) was required for maximal efficacy. These studies demonstrate that pre- and postoperative administration of either a steroidal (PNU74006F) or non-steroidal (PNU83,836E) lazaroid intraperitoneally reduced the formation and reformation of postoperative adhesions in three animal models.
Human Reproduction 10/1998; 13(9):2443-51. · 4.67 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The purpose of this study was to test the efficacy of three bioresorbable films of polyethylene glycol (EO) and polylactic acid (LA) (EO/LA = 1.5, 2.5, and 3.0) in the prevention of adhesion formation between the epicardium and the sternum (retrosternal adhesions) in a rabbit model. Retrosternal adhesions were generated by sternotomy, pericardiotomy, and abrasion of the anterior epicardium. The adhesion barrier was placed between the epicardium and the sternum and sutured to the edge of the pericardium. Epicardial adhesions were evaluated 14-20 days later by assessing the area of the epicardium covered by adhesions. In the control rabbits, tenacious adhesions were observed between sternum and the central portion of epicardium (portion exposed through the pericardiotomy) which were difficult to dissect. When a bioresorbable film was placed over the pericardium, adhesion formation at the central strip of the epicardium (area between the sternum and the epicardium exposed through the pericardium) could be reduced or prevented. At this site, the areas of adhesion formation were 0% (EO/LA = 1.5), 8.4 +/- 2.8% (EO/LA = 2.5), and 5.6 +/- 4.7% (EO/LA = 3.0) of the central strip, significantly less than that observed in the control group, 78.0 +/- 5.8% (P < 0.01). At the anterior left and right and posterior apex of the heart (sites where the film was not placed), there were no differences between control and treatment groups. The films were completely resorbed at the time of necropsy in group EO/LA = 2.5 and 3.0. Small pieces of film were observed in group EO/LA = 1.5. In conclusion, the bioresorbable films [EO/LA = 1.5 (REPEL-CV), 2.5, or 3.0] were efficacious in the reduction of retrosternal adhesions to the epicardium.
Journal of Surgical Research 08/1998; 78(2):118-22. · 2.02 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Adhesion formation is a major source of postoperative morbidity and mortality. Therefore, the reduction of postoperative adhesion formation would be of clinical benefit. Various modalities have been shown to reduce adhesion formation, including fibrinolytic enzymes, nonsteroidal anti-inflammatory drugs, and barriers that reduce the apposition of sites of potential adhesion formation. In this report, the ability of three compounds with different mechanisms of action, all-trans-retinoic acid, quinacrine, and dipyridamole, to reduce the formation of intraperitoneal adhesions was examined in two rabbit models. In the sidewall model, the medicaments were administered via an Alzet miniosmotic pump for the entire postoperative interval. With all three agents, there was a reduction in the area of the sidewall injury that was involved in adhesions to the cecum and the bowel at both doses tested. In the same model, quinacrine also reduced the area of the sidewall injury that was involved in adhesions to the cecum and the bowel. At the higher concentrations of quinacrine, there was a deposition and walling off of the quinacrine at the site of delivery. In the double uterine horn model (DUH), the medicaments were administered via an Alzet miniosmotic pump to the area of injury for either 1, 2, 3, or 7 days. Administration of all three compounds for as little as 24 h after surgery significantly reduced the extent of adhesion formation. However, there was a further reduction in the amount of adhesion when the retinoic acid or dipyridamole was administered for 72 h postoperatively. However, when the quinacrine was administered for longer times postoperatively, the amount of adhesion reduction observed was less. These studies demonstrate that postoperative administration of retinoic acid, quinacrine, or dipyridamole to the site of injury reduced the formation of postoperative adhesions in two animal models.
Journal of Investigative Surgery 01/1998; 11(5):327-39. · 1.32 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Malathion administration at non-cholinergical doses was shown to elevate macrophage, proliferative and humoral immune responses. This study examined the effects of malathion on autoimmunity, autoantibody formation, macrophage function and mitogenic responses in MRL-lpr mice (genetically predisposed to autoimmune disease) and MRL-+/+ mice. Malathion, 33-300mg/kg, was administered by gavage once per week, beginning at 6 weeks of age. At 300mg/kg in MRL-lpr mice, malathion administration accelerated the appearance of significant (>100mg/l) levels of urinary protein by approximately 3 weeks and increased the maximum level of protein detected. Increased urinary protein was delayed at lower doses of malathion, but was elevated compared to vehicle control. This increase in urinary protein was not observed in the group of MRL-+/+ mice. The popliteal and axillary lymph nodes (LN) were larger in malathion-treated (>33mg/kg) than in control mice at 19 weeks of age. Within the same time-frame in MRL-+/+ mice, malathion did not affect and increased the size of the axillary and popliteal LN, respectively. Rheumatoid factor (RF) and anti-DNA (dsDNA) antibodies in the serum were not elevated in any group of MRL-+/+ mice by 19 weeks of age. However, in the MRL-lpr mice, weekly malathion treatment (>33mg/kg) elevated the level of serum RF at 12 and 19 weeks of age. Malathion treatment (>100mg/kg) also increased the level of anti-dsDNA antibodies in the serum of MRL-lpr mice at 19 weeks of age. Malathion treatment increased the number of inflamed glomeruli. Histopathological analysis of various organs showed no effect on vasculitis after malathion treatment. Acute administration of 300mg/kg malathion to 6-week-old mice elevated the secretion of nitric oxide by peritoneal macrophages, but did not affect the secretion of tumor necrosis factor. In addition, the basal and mitogen-induced proliferation of splenocytes of malathion-treated MRL-lpr mice were elevated, but the stimulation index was unchanged.
Journal of Autoimmunity 09/1997; 10(4):367-73. · 8.15 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To examine the efficacy of various formulations of hyaluronic acid (HA), including HA ionically cross-linked with trivalent iron, in animal models of adhesion formation.
Hyaluronic acid formulation of varying concentrations and cross-linked densities were prepared and evaluated in a rabbit uterine horn model and a rabbit sidewall model.
ETHICON, Inc., Somerville, New Jersey.
New Zealand White rabbits.
Test formulations were applied as intraperitoneal instillates after surgery.
Adhesion formation was assessed at 7 and 14 days (sidewall and uterine horn model, respectively).
Hyaluronic acid that was not ionically cross-linked was ineffective in reducing adhesions in these models even at high viscosity, whereas the ionically cross-linked formulations of HA with trivalent iron were highly effective. Efficacy improved with increased levels of ionic cross-linking. Flowable gels, which could be delivered readily by syringe and cannula, also were effective when administered at a site remote from injury and with saline present.
Whereas previous studies show that HA was effective in reducing adhesions peripheral to the site of injury, HA ionically cross-linked with trivalent iron was effective in reducing adhesions at all sites. From these studies, a formulation of HA ionically cross-linked with trivalent iron, 0.5% Ferric Hyaluronate Gel (LUBRICOAT; ETHICON, Inc., Somerville, NJ), was identified for subsequent clinical evaluations.
Fertility and Sterility 08/1997; 68(1):37-42. · 4.17 Impact Factor