Role of nitric oxide in apoptosis of human peritoneal and adhesion fibroblasts after hypoxia

Biocompatible Nanocomposites for Postoperative Adhesion: A State-of-the-Art Review

To reduce and prevent postsurgical adhesions, a variety of scientific approaches have been suggested and applied. This includes the use of advanced therapies like tissue-engineered (TE) biomaterials and scaffolds. Currently, biocompatible antiadhesive constructs play a pivotal role in managing postoperative adhesions and several biopolymer-based products, namely hyaluronic acid (HA) and polyethylene glycol (PEG), are available on the market in different forms (e.g., sprays, hydrogels). TE polymeric constructs are usually associated with critical limitations like poor biocompatibility and mechanical properties. Hence, biocompatible nanocomposites have emerged as an advanced therapy for postoperative adhesion treatment, with hydrogels and electrospun nanofibers among the most utilized antiadhesive nanocomposites for in vitro and in vivo experiments. Recent studies have revealed that nanocomposites can be engineered to generate smart three-dimensional (3D) scaffolds that can respond to different stimuli, such as pH changes. Additionally, nanocomposites can act as multifunctional materials for the prevention of adhesions and bacterial infections, as well as tissue healing acceleration. Still, more research is needed to reveal the clinical potential of nanocomposite constructs and the possible success of nanocomposite-based products in the biomedical market.

Role of Amino Acid Arginine and Nitric Oxide in Mechanisms of Cytoprotective Effect of Non-Opiate Leu-Enkephalin Analogue In Vitro

Incubation of primary culture of pulmonary fibroblasts with non-opiate analogue of leuenkephalin (NALE; Phe-D-Ala-Gly-Phe-Leu-Arg, 0.1 μM) reduced generation of superoxide anion-radical (by 20.7%) and decreased the number of p53⁺ cells (by 40.2%) induced by exposure to H₂O₂ (60 μM). The cytoprotective effect of NALE was potentiated by NO synthase inhibitor L-NAME (1 mM): the number of p53⁺ cells decreased by 65.3% and morphometric parameters of the cell nuclei and nucleoli were improved. Incubation of pulmonary fibroblasts culture with peptide G (Phe-D-Ala-Gly-Phe-Leu-Gly, 0.1 μM) also significantly reduced the damaging effect of H₂O₂: the number of p53⁺ cells decreased by 73.5%, the area of cell nuclei returned to normal, and generation of superoxide anion-radical decreased by 18.4%. These results indicate that C-terminal amino acid Arg and activation of NO synthase are not involved in the direct cytoprotective effect of NALE.

Is There a Genetic Predisposition to Postoperative Adhesion Development?

Adhesions are permanent fibrovascular bands between peritoneal surfaces, which develop following virtually all body cavity surgeries. The susceptibility to develop, and the severity, of adhesions following intra-abdominal surgery varies within and between individuals, suggesting that heritable factors influence adhesion development. In this manuscript, we discuss the pathophysiology of adhesion development from the perspective of genetic susceptibility. We restrict our discussion to genes and single-nucleotide polymorphisms (SNPs) that are specifically involved in, or that cause modification of, the adhesion development process. We performed a literature search using the PubMed database for all relevant English language articles up to March 2020 (n = 186). We identified and carefully reviewed all relevant articles addressing genetic mutations or single-nucleotide polymorphisms (SNPs) that impact the risk for adhesion development. We also reviewed references from these articles for additional information. We found several reported SNPs, genetic mutations, and upregulation of messenger RNAs that directly or indirectly increase the propensity for postoperative adhesion development, namely in genes for transforming growth factor beta, vascular endothelial growth factor, interferon-gamma, matrix metalloproteinase, plasminogen activator inhibitor-1, and the interleukins. An understanding of genetic variants could provide insight into the pathophysiology of adhesion development. The information presented in this review contributes to a greater understanding of adhesion development at the genetic level and may allow modification of these genetic risks, which may subsequently guide management in preventing and treating this challenging complication of abdominal surgery. In particular, the information could help identify patients at greater risk for adhesion development, which would make them candidates for anti-adhesion prophylaxis. Currently, agents to reduce postoperative adhesion development exist, and in the future, development of agents, which specifically target individual genetic profile, would be more specific in preventing intraperitoneal adhesion development.

Evitar (l-Alanyl-l-Glutamine) Regulates Key Signaling Molecules in the Pathogenesis of Postoperative Tissue Fibrosis

Aims:

Hypoxia and the resulting oxidative stress play a major role in postoperative tissue fibrosis. The objective of this study was to determine the effect of l-alanyl-l-glutamine (Ala-Gln) on key markers of postoperative tissue fibrosis: hypoxia-inducible factor (HIF) 1α and type I collagen.

Methods:

Primary cultures of human normal peritoneal fibroblasts (NPF) established from normal peritoneal tissue were treated with increasing doses of Ala-Gln (0, 1, 2, or 10 mM) with hypoxia ([2% O2] 0-48 hours; continuous hypoxia) or after hypoxia (0.5, 1, 2, 4 hours) and restoration of normoxia (episodic hypoxia) with immediate treatment with Ala-Gln. Hypoxia-inducible factor 1α and type 1 collagen levels were determined by enzyme-linked immunosorbent assay. Data were analyzed with 1-way analysis of variance followed by Tukey tests with Bonferroni correction.

Results:

Hypoxia-inducible factor 1α and type I collagen levels increased in untreated controls by 3- to 4-fold in response to continuous and episodic hypoxia in human NPF. Under continuous hypoxia, HIF-1α and type I collagen levels were suppressed by Ala-Gln in a dose-dependent manner. l-alanyl-l-glutamine treatment after episodic hypoxia also suppressed HIF-1α and type I collagen levels for up to 24 hours for all doses and up to 48 hours at the highest dose, regardless of exposure time to hypoxia.

Conclusions:

l-alanyl-l-glutamine significantly suppressed hypoxia-induced levels of key tissue fibrosis (adhesion) phenotype markers under conditions of continuous as well as episodic hypoxia in vitro. This effect of glutamine on molecular events involved in the cellular response to insult or injury suggests potential therapeutic value for glutamine in the prevention of postoperative tissue fibrosis.

Adhesion phenotype manifests an altered metabolic profile favoring glycolysis

OBJECTIVE

To determine whether metabolic markers are differentially expressed in normal and adhesion fibroblasts with and without hypoxia exposure.

DESIGN

Prospective experimental study.

SETTING

University research laboratory.

PATIENT(S)

Fibroblasts established from normal peritoneum and adhesion tissues from the same patients.

INTERVENTION(S)

In vitro experiments on normal peritoneal and adhesion fibroblasts under normal and hypoxic (2% O2) conditions.

MAIN OUTCOME MEASURE(S)

Expression of metabolic markers, glyceraldehyde 3-phosphate dehydrogenase (GAPDH), glucose transporter 1 (GLUT1), hypoxia inducible factor (HIF)-1α, hexokinase 2 (HK2), lactose dehydrogenase A (LDHA), and pyruvate dehydrogenase alpha 1 (PDHA1) were measured using real-time reverse transcription polymerase chain reaction; adenosine triphosphate (ATP), HIF-1α, and lactate levels were assessed with ELISAs.

RESULT(S)

Baseline mRNA levels of GAPDH and HIF-1α were increased, while GLUT1 and PDHA1 were decreased in adhesion as compared with in normal peritoneal fibroblasts. There was no change in baseline levels of HK2 or LDHA between the cell lines. Hypoxia increased protein levels of HIF-1α and mRNA levels of GAPDH, GLUT1, and HK2 and decreased levels of PDHA1 in both cell lines. Hypoxia increased LDHA mRNA levels in normal peritoneal fibroblasts. Baseline levels of lactate and ATP were lower in adhesion as compared with in normal peritoneal fibroblasts. In response to hypoxia, there was an increase in lactate in both cell lines and a decrease in ATP in normal fibroblasts.

CONCLUSION(S)

Adhesion fibroblasts manifested an altered metabolic profile, which favors the glycolytic pathway, and is further altered by hypoxia. Targeting these specific metabolic markers during surgery can be an important therapeutic intervention minimizing the development of postoperative adhesions.

Advances in the Pathogenesis of Adhesion Development: The Role of Oxidative Stress

Over the past several years, there has been increasing recognition that pathogenesis of adhesion development includes significant contributions of hypoxia induced at the site of surgery, the resulting oxidative stress, and the subsequent free radical production. Mitochondrial dysfunction generated by surgically induced tissue hypoxia and inflammation can lead to the production of reactive oxygen and nitrogen species as well as antioxidant enzymes such as superoxide dismutase, catalase, and glutathione peroxidase which when optimal have the potential to abrogate mitochondrial dysfunction and oxidative stress, preventing the cascade of events leading to the development of adhesions in injured peritoneum. There is a significant cross talk between the several processes leading to whether or not adhesions would eventually develop. Several of these processes present avenues for the development of measures that can help in abrogating adhesion formation or reformation after intraabdominal surgery.

Nicotinamide Adenine Dinucleotide Phosphate Oxidase Expression Is Differentially Regulated to Favor a Pro-oxidant State That Contributes to Postoperative Adhesion Development

We have previously reported that superoxide (O₂^•-) contributes to the development of postoperative adhesions. In this study, we determined whether O₂^•- generating nicotinamide adenine dinucleotide phosphate oxidase (NOX) is differentially expressed in normal peritoneal and adhesion fibroblasts and tissues. The NOX isoforms were measured utilizing Western blot, immunohistochemistry, high-performance liquid chromatography, and real-time reverse transcription polymerase chain reaction. Expression and activity of NOX were found to be significantly higher in adhesion tissues and cells than that in normal peritoneal tissues and cells (P < .05). Levels of NOX2, NOX4, NOX activating protein 1, DUOX1, p47^phox, and p22^phox messenger RNA increased in adhesion fibroblasts when compared to normal peritoneal and increased in response to hypoxia in normal peritoneal fibroblasts. Thus, adhesion fibroblasts are characterized by a unique NOX expression profile, which maintains a pro-oxidant state that may be responsible for the persistence of the adhesion phenotype. Decreasing the activity of NOX by targeting these isoforms may be beneficial for future therapeutic interventions of postoperative adhesions.

Lycopene, a powerful antioxidant, significantly reduces the development of the adhesion phenotype

Postoperative adhesions are a common medical complication of gynecologic and other pelvic surgeries resulting in persistent pelvic pain, obstruction of the intestines, and even infertility. The molecular mechanisms of postoperative adhesion development remain to be elucidated. We have recently described a role for reactive oxygen species, specifically superoxide, in the development of postoperative adhesions. In this study, we sought to determine whether lycopene, a potent antioxidant, reduces markers characteristic of the adhesion phenotype. Primary fibroblast cultures from normal peritoneum and adhesion tissues were utilized to determine mRNA levels of adhesion phenotype markers type I collagen, transforming growth factor-beta 1 (TGF-β1), and vascular endothelial growth factor (VEGF) in response to lycopene (24 hours, 10 μM) treatment. There was a 2 (p < 0.003), 4.7 (p < 0.004), and 1.6 fold (p < 0.004) increase in mRNA levels of type I collagen, TGF-β1, and VEGF, respectively, in adhesion as compared to normal peritoneal fibroblasts. Lycopene treatment led to a 6.8 and a 12.4 fold decrease in type I collagen mRNA levels, in normal peritoneal and adhesion fibroblasts, respectively (p < 0.005). Lycopene treatment led to a 4.2 (p < 0.03) and a 4.6 (p < 0.05) fold decrease in VEGF mRNA levels, in normal peritoneal and adhesion fibroblasts, respectively. Lycopene treatment led to a 7.0 fold decrease in TGF-β1 mRNA levels, in adhesion fibroblasts (p < 0.03). A 1.9 fold decrease in TGF-β1 mRNA was observed in normal peritoneal fibroblasts in response to treatment, although it was not significant. Lycopene substantially reduced levels of adhesion phenotype markers in normal peritoneal and adhesion fibroblasts and whether it will reduce postoperative adhesions needs to be further investigated.

Effects of hypoxia on the expression of inflammatory markers IL-6 and TNF-a in human normal peritoneal and adhesion fibroblasts

Inflammation is known to be involved in the postoperative adhesion development. Interleukin (IL)-6 and tumor necrosis factor (TNF)-α are cytokines that stimulate the acute-phase reaction, which leads to a systemic reaction including inflammation, fever, and activation of the complement and clotting cascades. The goal of this study was to examine the expression of these inflammatory markers, under normal and hypoxic conditions, in normal and adhesion fibroblasts. Primary cultures of fibroblasts were established from normal peritoneum and adhesion tissues from the same patient(s) and cultured under 20% O(2) or hypoxic 2% O(2) conditions for 24 hours. Cells were harvested and total RNA was isolated. Complimentary DNA was generated by reverse transcription and subjected to real-time RT-PCR using specific primers for IL-6 and TNF-α. Both normal peritoneal and adhesion fibroblasts expressed IL-6 and TNF-α. Adhesion fibroblasts exhibited significantly higher levels of IL-6 and TNF-α mRNA as compared to normal peritoneal fibroblasts (p < 0.05). Both IL-6 and TNF-α mRNA levels were upregulated in response to hypoxia in both normal peritoneal and adhesion fibroblasts. The increase in IL-6 and TNF-α mRNA levels of normal fibroblasts reached the levels observed in adhesion fibroblasts. Our results suggest that hypoxia promotes the development of the adhesion phenotype by the induction of inflammatory markers, which may contribute to the development of postoperative adhesions. The inhibition of inflammation may be a potential therapeutic approach in the prevention and/or reduction of postoperative adhesion development.

Postoperative adhesion development following cesarean and open intra-abdominal gynecological operations: a review

In this review, we discuss the pathophysiology of adhesion development, the impact of physiological changes associated with pregnancy on markers of adhesion development, and the clinical implications of adhesion development following cesarean delivery (CD). Although peritoneal adhesions develop after the overwhelming majority of intra-abdominal and pelvic surgery, there is evidence in the literature that suggests that patients having CD may develop adhesions less frequently. However, adhesions continue to be a concern after CD, and are likely significant, albeit on average less than after gynecological operations, but with potential to cause significant delay in the delivery of the baby with serious, lifelong consequences. Appreciation of the pathophysiology of adhesion development described herein should allow a more informed approach to the rapidly evolving field of intra-abdominal adhesions and should serve as a reference for an evidence-based approach to consideration for the prevention and treatment of adhesions.

Myeloperoxidase serves as a redox switch that regulates apoptosis in epithelial ovarian cancer

OBJECTIVES

Resistance to apoptosis is a key feature of cancer cells and is believed to be regulated by nitrosonium ion (NO(+))-induced S-nitrosylation of key enzymes. Nitric oxide (NO), produced by inducible nitric oxide synthase (iNOS), is utilized by MPO to generated NO(+). We sought to investigate the expression of myeloperoxidase (MPO) and iNOS in epithelial ovarian cancer (EOC) and determine their effect on S-nitrosylation of caspase-3 and its activity as well as apoptosis.

METHODS

MPO and iNOS expression were determined using immunofluorescence in SKOV-3 and MDAH-2774 and EOC tissue sections. S-nitrosylation of caspase-3 and its activity, levels of MPO and iNOS, as well as apoptosis, were evaluated in the EOC cells before and after silencing MPO or iNOS genes with specific siRNA probes utilizing real-time RT-PCR, ELISA, and TUNEL assays.

RESULTS

MPO and iNOS are expressed in EOC cell lines and in over 60% of invasive EOC cases with no expression in normal ovarian epithelium. Indeed, silencing of MPO or iNOS gene expression resulted in decreased S-nitrosylation of caspase-3, increased caspase-3 activity, and increased apoptosis but with a more significant effect when silencing MPO.

CONCLUSION

MPO and iNOS are colocalized to the same cells in EOC but not in the normal ovarian epithelium. Silencing of either MPO or iNOS significantly induced apoptosis, highlighting their role as a redox switch that regulates apoptosis in EOC. Understanding the mechanisms by which MPO functions as a redox switch in regulating apoptosis in EOC may lead to future diagnostic tools and therapeutic interventions.

S-nitrosylation of caspase-3 is the mechanism by which adhesion fibroblasts manifest lower apoptosis

We have previously found that adhesion fibroblasts exhibit lower apoptosis and higher protein nitration as compared with normal peritoneal fibroblasts. In this study, we sought to determine whether the decreased apoptosis observed in adhesion fibroblasts is caused by lower caspase-3 activity due to an increase in caspase-3 S-nitrosylation. For this study, we have utilized primary cultures of fibroblasts obtained from normal peritoneum and adhesion tissues of the same patient(s). Cells were treated with increasing concentrations of peroxynitrite and cell lysates were immunoprecipitated with anti-caspase-3 polyclonal antibody. The biotinylated proteins were detected using a nitrosylation detection kit. Caspase-3 activity and apoptosis were measured by colorimetric and TUNEL assays, respectively. Our results showed that caspase-3 S-nitrosylation is significantly higher in adhesion fibroblasts as compared with normal peritoneal fibroblasts. This increase in S-nitrosylation resulted in a 30% decrease in caspase-3 activity in adhesion fibroblasts. Peroxynitrite treatment resulted in a dose response increase in caspase-3 S-nitrosylation, leading to a decrease in caspase-3 activity and apoptosis in normal peritoneal fibroblasts. We conclude that S-nitrosylation of caspase-3 is the reason for its decreased activity and subsequent decrease in apoptosis of adhesion fibroblasts. The mechanism by which caspase-3 S-nitrosylation occurs is not fully understood. However, the role of hypoxia in the formation of peroxynitrite via superoxide production may suggest a possible mechanism.

Hypoxia-generated superoxide induces the development of the adhesion phenotype

Adhesion fibroblasts exhibit higher TGF-beta1 and type I collagen expression as compared to normal peritoneal fibroblasts. Furthermore, exposure of normal peritoneal fibroblasts to hypoxia results in an irreversible increase in TGF-beta1 and type I collagen. We postulated that the mechanism by which hypoxia induced the adhesion phenotype is through the production of superoxide either directly or through the formation of peroxynitrite. To test this hypothesis, normal peritoneal and adhesion fibroblasts were treated with superoxide dismutase (SOD), a superoxide scavenger, and xanthine/xanthine oxidase, a superoxide-generating system, under normoxic and hypoxic conditions. Also, cells were treated with peroxynitrite. TGF-beta1 and type I collagen expression was determined before and after all treatments using real-time RT/PCR. Hypoxia treatment resulted in a time-dependent increase in TGF-beta1 and type I collagen mRNA levels in both normal peritoneal and adhesion fibroblasts. Similarly, treatment with xanthine oxidase, to endogenously generate superoxide, resulted in higher mRNA levels of TGF-beta1 and type I collagen in both normal peritoneal and adhesion fibroblasts. In contrast, treatment with SOD, to scavenge endogenous superoxide, resulted in a decrease in TGF-beta1 and type I collagen expression in adhesion fibroblasts to levels seen in normal peritoneal fibroblasts; no effect on the expression of these molecules was seen in normal peritoneal fibroblasts. Exposure to hypoxia in the presence of SOD had no effect on mRNA levels of TGF-beta1 and type I collagen in either normal peritoneal or adhesion fibroblasts. Peroxynitrite treatment alone significantly induced both adhesion phenotype markers. In conclusion, hypoxia, through the production of superoxide, causes normal peritoneal fibroblasts to acquire the adhesion phenotype. Scavenging superoxide, even in the presence of hypoxia, prevented the development of the adhesion phenotype. These findings further support the central role of free radicals in the development of adhesions.

Nitric oxide synthase isoforms expression in fibroblasts isolated from human normal peritoneum and adhesion tissues

OBJECTIVE

To determine the expression of nitric oxide synthases (NOSs) and their modulation by hypoxia in human peritoneal (NF) and adhesion fibroblasts (ADF).

DESIGN

Prospective experimental study.

SETTING

University medical center.

PATIENT(S)

Fibroblasts from peritoneum and adhesion tissues.

INTERVENTION(S)

Hypoxia and silencing inducible NOS (iNOS) gene expression in fibroblasts.

MAIN OUTCOME MEASURE(S)

We used reverse-transcriptase polymerase chain reaction to quantify messenger RNA (mRNA) levels of NOS isoforms. Griess assay was used to measure NO levels.

RESULT(S)

The mRNA copies/mug RNA of neuronal NOS (nNOS) and endothelial NOS (eNOS) were 6.6 x 10(3) in NF, 5.7 x 10(3) in ADF and 7.0 x 10(3) in NF, 6.1 x 10(3) in ADF, respectively. The mRNA copies/mug RNA of iNOS were 31.3 x 10(3) in NF and 33.0 x 10(3) in ADF. Hypoxia increased iNOS mRNA copies/mug RNA from 31.3 x 10(3) to 61.3 x 10(3) in NF and from 33.0 x 10(3) to 63.9 x 10(3) in ADF, whereas there were no changes in mRNA levels of nNOS and eNOS in NF and ADF. Nitric oxide levels were lower in ADF (0.94 micromol/L) than NF (1.97 micromol/L). Silencing iNOS decreased NO levels in NF (from 1.97 micromol/L to 0.41 micromol/L) and in ADF (from 0.94 micromol/L to 0.27 micromol/L).

CONCLUSION(S)

Nitric oxide synthases are differentially expressed in NF and ADF, with iNOS being the most expressed and the main source of NO. Hypoxia was shown to alter the expression of NOSs and NO in NF and ADF.

Hypoxia regulates iNOS expression in human normal peritoneal and adhesion fibroblasts through nuclear factor kappa B activation mechanism

OBJECTIVE

To determine the mechanism by which hypoxia increases expression of iNOS in human normal peritoneal and adhesion fibroblasts.

DESIGN

Prospective experimental study.

SETTING

University medical center.

PATIENT(S)

Primary cultures of fibroblasts from normal peritoneum and adhesion tissues.

INTERVENTION(S)

Hypoxia-treated cells.

MAIN OUTCOME MEASURE(S)

We used real-time reverse transcription-polymerase chain reaction to quantify mRNA levels of iNOS and nuclear factor kappa B (NF-kappaB). Western blots were used to determine iNOS, NF-kappaB, IkappaB-alpha, and phospho-IkappaB expression levels in normal peritoneal and adhesion fibroblasts in response to hypoxia.

RESULT(S)

Hypoxia resulted in a significant increase in iNOS and NF-kappaB expression in normal and adhesion fibroblasts. Furthermore, both cell types manifested lower levels of NF-kappaB, cytoplasmic phospho-IkappaB-alpha, and iNOS proteins. In contrast, they manifested higher levels of cytoplasmic IkappaB-alpha and IkappaB-alpha/NF-kappaB ratios as well as a phosphorylated-IkappaB-alpha/NF-kappaB ratio. Under hypoxic conditions, both cell types exhibited significantly decreased cytoplasmic NF-kappaB, IkappaB-alpha levels, and significantly increased cytoplasmic phospho-IkappaB-alpha, iNOS, and NF-kappaB protein levels.

CONCLUSION(S)

Hypoxia increases iNOS expression by a mechanism involving activation of NF-kappaB. The ratio of IkappaB-alpha/NF-kappaB or IkappaB-alpha/p-IkappaB-alpha can be used to monitor activation.

Melatonin prevents nitric oxide-induced apoptosis by increasing the interaction between 14-3-3beta and p-Bad in SK-N-MC cells

The anti-apoptotic effect of melatonin has been described in vivo and in vitro. A previous report has revealed that melatonin suppresses nitric oxide (NO)-induced apoptosis via the induction of Bcl-2 expression in PGT-beta pineal cells. To investigate the protective mechanism of melatonin on NO donor S-nitroso-N-acetyl-penicillamine (SNAP)-induced apoptosis, we examined the anti-apoptotic upstream signaling pathway of Bcl-2 in the human neuroblastoma cell line SK-N-MC. The flow cytometry results revealed that apoptosis occurred in NO-treated cells, while cell death was inhibited by pretreatment with melatonin (100 microm). In addition, decreased Bax expression, increased Bcl-2 expression and a decreased release of cytochrome c into the cytosol were observed in the melatonin-pretreated SK-N-MC cells. We also found that melatonin treatment induced the activation of Akt/PKB and the phosphorylation of GSK3alpha/beta and Bad. Furthermore, melatonin treatment not only increased the protein-protein interactions between 14-3-3beta and p-Bad, but also decreased the release of cytochrome c from mitochondria into the cytosol. In summary, the protective effect of melatonin against NO-induced apoptosis was mediated by the inhibition of Bad translocation from the cytosol to the mitochondria by the induction of protein-protein interactions between 14-3-3beta and p-Bad.

Sildenafil reduces postoperative adhesion formation in a rat uterine horn model

OBJECTIVE

The purpose of this experimental study was to evaluate the effect of oral sildenafil on postoperative adhesion formation in rats.

STUDY DESIGN

Thirty-two Wistar Albino rats were subjected to standardized lesion by cauterization of the uterine horn and abrasion of the adjacent parietal peritoneum. They were randomized to receive sildenafil at a daily dose of 15 mg/kg, 7.5mg/kg and 3.75 mg/kg or placebo. Sildenafil was administered by gavage 1h before the operation and daily for 5 days after the procedure. The extent and severity of adhesions were assessed on the 14th postoperative day.

RESULT(S)

The severity but not extent of adhesions in rats given 15 mg/kg sildenafil was significantly less when compared with the other groups (<0.001).

CONCLUSION

Sildenafil diminishes peritoneal adhesion formation in rat.

Peritoneal adhesions and intestinal obstructions in patients with familial Mediterranean fever--are they more frequent?

OBJECTIVE

Familial Mediterranean fever (FMF) is characterized by recurrent episodes of peritonitis. A controversy exists as to whether intestinal obstruction due to peritoneal adhesions is more common among FMF patients compared with healthy controls. The aim of the study was to estimate the rate of spontaneous or postsurgical small-bowel obstruction (SBO) in FMF patients.

METHODS

We reviewed the charts of 560 FMF patients followed in our clinic for the occurrence of spontaneous SBO. We also assessed the occurrence of postappendectomy intestinal obstruction among 89 FMF patients compared with 417 individuals without FMF who underwent an appendectomy without other abdominal surgery in the same medical center.

RESULTS

Ten of 471 FMF patients (2.1%) developed spontaneous SBO, 8 of whom required laparotomy and adhesiolysis. Six of 89 FMF patients (6.7%) who underwent appendectomy developed SBO. None of the non-FMF patients developed SBO.

CONCLUSIONS

Our retrospective study showed that FMF patients are at a higher risk than healthy individuals for developing SBO either spontaneously or as a postsurgical complication. Physicians should be alert to this possible complication when FMF patients arrive at the emergency room.

Altered in vitro immune response to hypoxia-treated normal peritoneal fibroblasts

Hypoxia treatment of normal peritoneal fibroblasts results in alterations that are characteristic for fibroblasts obtained from postoperative peritoneal adhesion tissue. In this study, we have shown that hypoxia treatment enhances normal peritoneal fibroblast elimination by lymphokine-activated killer cells to the level of adhesion tissue fibroblasts, suggesting a pivotal role of hypoxia in the adhesion development.

Female infertility and free radicals: potential role in adhesions and endometriosis

Free radicals are highly reactive molecules produced in the cell either as part of, or as end-products of, biochemical reactions that have crucial roles in the homeostasis of the organism. Thus, excess production or impaired elimination of free radicals leads to increased oxidative stress, which has been implicated in the development of several different disease states, including hypoxia-reperfusion injury, cancer, and aging. Peritoneal adhesions and endometriosis are relatively commonly identified in women, and are known to be associated with infertility without clearly understood pathophysiology. The prevention and treatment strategies of these conditions, both of which have tremendous propensity to recur, have not been completely established. The development of both disorders has been shown to be closely related to the presence of increased oxidative stress in the tissues. In this article, we review this relationship with reference to the mechanistic steps involved and their regulation. As our knowledge of both conditions expands, we believe there will be opportunities for specific steps to intervention in free radical metabolism to reduce and/or prevent further development of endometriosis and adhesions.

Measurement of oxygen and nitric oxide levels in vitro and in vivo: relationship to postoperative adhesions

This article demonstrates the ability to measure the actual oxygen and nitric oxide levels in cultured fibroblasts established from normal peritoneum and adhesion tissues with and without hypoxia treatment and to measure levels of oxygen and nitric oxide in vivo in various tissues before and after abrasion.