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

Intraperitoneal Triamcinolone Reduces Postoperative Adhesions, Possibly through Alteration of Mitochondrial Function

Adhesions frequently occur postoperatively, causing morbidity. In this noninterventional observational cohort study, we enrolled patients who presented for repeat abdominal surgery, after a history of previous abdominal myomectomy, from March 1998 to June 20210 at St. Vincent’s Catholic Medical Centers. The primary outcome of this pilot study was to compare adhesion rates, extent, and severity in patients who were treated with intraperitoneal triamcinolone acetonide during the initial abdominal myomectomy (n = 31) with those who did not receive any antiadhesion interventions (n = 21), as documented on retrospective chart review. Adhesions were blindly scored using a standard scoring system. About 32% of patients were found to have adhesions in the triamcinolone group compared to 71% in the untreated group (p < 0.01). Compared to controls, adhesions were significantly less in number (0.71 vs. 2.09, p < 0.005), severity (0.54 vs. 1.38, p < 0.004), and extent (0.45 vs. 1.28, p < 0.003). To understand the molecular mechanisms, human fibroblasts were incubated in hypoxic conditions and treated with triamcinolone or vehicle. In vitro studies showed that triamcinolone directly prevents the surge of reactive oxygen species triggered by 2% hypoxia and prevents the increase in TGF-β1 that leads to the irreversible conversion of fibroblasts to an adhesion phenotype. Triamcinolone prevents the increase in reactive oxygen species through alterations in mitochondrial function that are HIF-1α-independent. Controlling mitochondrial function may thus allow for adhesion-free surgery and reduced postoperative complications.

Tranexamic acid and hyaluronate/carboxymethylcellulose create cell injury

Background and Objectives:

Postoperative pelvic adhesions are associated with chronic pelvic pain, dyspareunia, and infertility. The aim of this study was to evaluate the adhesion prevention effects of tranexamic acid (TA) and hyaluronate/carboxymethylcellulose (HA/CMC) barrier in the rat uterine horn models on the basis of macroscopic and microscopic adhesion scores and histopathological as well as biochemical parameters of inflammation.

Methods:

Twenty-one Wistar rats were randomly divided into 3 groups. Ten lesions were created on the antimesenteric surface of both uterine horns by bipolar cautery. Three milliliters of 0.9% sodium chloride solution were administered in the control group. A single layer of 2 × 2 cm HA/CMC was plated in group 2. Two milliliters of TA was applied in the last group. All rats were sacrificed at postoperative day 21.

Results:

No significant difference was found among the control group, the HA/CMC group, and the TA group in terms of macro-adhesion score (P = .206) and microadhesion score (P = .056). No significant difference was found among the 3 groups in terms of inflammation score (P = .815) and inflammatory cell activity (P = .835). Malondialdehyde levels were significantly lower in the control group than in the TA group and HA/CMC group (P = .028). Superoxide dismutase and glutathione S-transferase activities were found to be higher in the control group than in the TA group (P = .005) and HA/CMC group (P = .009).

Conclusions:

TA and HA/CMC had no efficacy in preventing macroscopic or microscopic adhesion formation and decreasing inflammatory cell activity or inflammation score in our rat models. TA and HA/CMC increased the levels of free radicals and reduced the activities of superoxide dismutase and glutathione S-transferase enzymes, which act to reduce tissue injury.

Direct real-time measurement of intra-oocyte nitric oxide concentration in vivo

Nitric oxide (NO) is reported to play significant a role in oocyte activation and maturation, implantation, and early embryonic development. Previously we have shown that NO forms an important component of the oocyte microenvironment, and functions effectively to delay oocyte aging. Thus, precise information about intra-oocyte NO concentrations [NO] will result in designing more accurate treatment plans in assisted reproduction. In this work, the direct, real-time and quantitative intra-oocyte [NO] was measured utilizing an L-shaped amperometric integrated NO-selective electrode. This method not only provides an elegant and convenient approach to real-time the measurement of NO in physiological environments, but also mimics the loss of NO caused by rapid NO diffusion combined with its reactivity in the biological milieu. This experiment suggests that the NO levels of oocytes obtained from young animals are significantly higher than those of oocytes obtained from old animals. Additionally the NO levels stay constant during the measurements; however, the intra-oocyte [NO] is reduced significantly (70-75% reduction) in response to L-NAME incubation, suggesting that NO measurements are truly NOS based rather than caused by an unknown interfering substance in our system. We believe this first demonstration of the direct quantitative measurement of [NO] in situ in an intact cellular complex should be useful in tracking real-time and rapid changes at nanomolar levels. Moreover, this finding confirms and extends our previous work showing that supplementation with NO delays the oocyte aging process.

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.

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.

Prevention of peritoneal adhesions: a promising role for gene therapy

Adhesions are the most frequent complication of abdominopelvic surgery, yet the extent of the problem, and its serious consequences, has not been adequately recognized. Adhesions evolved as a life-saving mechanism to limit the spread of intraperitoneal inflammatory conditions. Three different pathophysiological mechanisms can independently trigger adhesion formation. Mesothelial cell injury and loss during operations, tissue hypoxia and inflammation each promotes adhesion formation separately, and potentiate the effect of each other. Studies have repeatedly demonstrated that interruption of a single pathway does not completely prevent adhesion formation. This review summarizes the pathogenesis of adhesion formation and the results of single gene therapy interventions. It explores the promising role of combinatorial gene therapy and vector modifications for the prevention of adhesion formation in order to stimulate new ideas and encourage rapid advancements in this field.

The effect of hypoxia and cycloxygenase inhibitors on nasal polyp derived fibroblasts

BACKGROUND AND PURPOSE

The pathogenesis of chronic rhinosinusitis with nasal polyposis is unknown. Chronic inflammation along with local tissue hypoxia may effect polyp's growth. Activation of Cycloxygenases may also be involved. COX-2 up-regulates in response to different stimuli including hypoxia. Its activation is associated with enhanced cell proliferation. Histologically, besides inflammatory cells, increased stromal fibrosis is seen in nasal polyposis. The aims of this study were to test whether hypoxia amplifies nasal polyp fibroblasts proliferation, whether treatment with various COX inhibitors could influence fibroblasts, and whether this effect may be modulated in response to different oxygenation conditions.

MATERIALS AND METHODS

Polyp fibroblasts were incubated under hypoxic or normoxic conditions with or without NSAIDs at different concentrations for 12 or 24 hours. Cell proliferation was quantified using BrdU ELISA. Metabolic activity was evaluated using MTT assay. Cell death was measured using Annexin V staining and FACS scan.

RESULTS

No significant difference was found between proliferation of fibroblasts treated under hypoxia or normoxia. Cells incubated with indomethacin proliferated in a slightly enhanced manner compared with non-treated cells. Celecoxib inhibited fibroblast proliferation (P < .001) but did not influence cell survival. Metabolic activity of cells treated with celecoxib was significantly reduced (P < .003), unlike cells treated with indomethacin or rofecoxib.

CONCLUSION

Hypoxia does not affect fibroblasts proliferation. It may contribute to nasal polyposis pathogenesis in other ways. The anti-proliferative effect of celecoxib may be associated with cell cycle arrest rather than with pro-apoptotic activity. Celecoxib may be considered for treating nasal polyposis.

In vivo measurement of facet joint nitric oxide in patients with chronic low back pain

STUDY DESIGN

Prospective case-control study testing a new diagnostic method.

OBJECTIVE

The aim of the present study was to investigate the concentration of nitric oxide (NO) in the perifacetal region in patients with chronic low back pain and healthy controls.

SUMMARY OF BACKGROUND DATA

Facet joint arthrosis may be a pain source in chronic back pain. Increased concentrations of NO, an oxygen-free radical, have been demonstrated in temporomandibular and knee joints with osteoarthritis.

PATIENTS AND METHODS

Patients with at least 6 months' duration of chronic low back pain and signs of facet joint osteoarthrosis (n = 24) and healthy volunteers (n = 7) were included. A detailed questionnaire, including visual analogue scale, was completed before and 6 weeks after the measurements. NO was measured with a custom-designed electrochemical real-time NO sensor inserted under fluoroscopic guidance. All patients received corticosteroids and local anesthetics after NO measurements.

RESULTS

NO measurements were obtained from all participants. No adverse effects were noted. The patients with chronic low back pain demonstrated higher concentrations of NO in the perifacetal region compared with healthy controls (1.66 +/- 0.28 vs. 0.46 +/- 0.14 nmol/L, P = 0.007). No association between NO concentration and pain duration or pain level was detected. Patients with a positive response to local anesthetics and corticosteroid injection (defined as a >or=20 mm reduction of visual analogue scale at the 6-week follow-up visit) had higher NO concentrations than patients without positive response.

CONCLUSIONS

The study demonstrates that it is feasible and safe to measure NO with a real time-sensor in or around the facet joints. The findings of higher concentrations of NO in the perifacetal region in chronic low back patients compared with healthy controls indicate that the degenerative process of the joints in these patients may cause increased NO production. The observation of higher NO concentrations in the perifacetal region in patients responding to corticosteroid/local anesthetic infiltration indirectly suggest a more pronounced inflammatory process in these patients.