Oxidative stress in Complex Regional Pain Syndrome (CRPS): no systemically elevated levels of malondialdehyde, F2-isoprostanes and 8OHdG in a selected sample of patients

Exploring the role of oxidative stress and the effect of N-acetylcysteine in thiopurine-induced liver injury in inflammatory bowel disease: A randomized crossover pilot study

Thiopurine treatment is regularly complicated by drug-induced liver injury. It has been suggested that oxidative stress may play a synergistic role. To assess whether thiopurine-induced liver injury coincides with increased oxidative stress and whether co-administration with N-acetylcysteine is protective, we performed a randomized open label crossover pilot study in inflammatory bowel disease patients with thiopurine-induced increased serum liver tests. The study comprised four stages of 4 weeks. Patients received no additional therapy followed by N-acetylcysteine 1200 mg twice a day, or the other way around, alongside ongoing thiopurine treatment. The third and fourth stages comprised a washout period and thiopurine reintroduction period. Nine patients completed the study, and the addition of N-acetylcysteine decreased myeloperoxidase concentrations (33.6-24.5 pmol/L, p = 0.038). The other biomarkers remained unchanged, including thiopurine metabolites, xanthine oxidase activity, thiopurine S-methyltransferase activity and serum liver enzyme activity tests. Reintroduction of thiopurines led to an increase of F2-isoprostanes (101-157 ng/mmol, p = 0.038), but not of serum liver enzyme activity tests. Results suggests that thiopurines may increase oxidative stress and although the addition of N-acetylcysteine led to a decrease in plasma myeloperoxidase concentrations, it does not protect from thiopurine-induced increase of serum liver tests.

Preliminary Study on the Antioxidant Effect of Natural Based Products with Potential Application in Complex Regional Pain Syndrome

Complex regional pain syndrome (CRPS) is a complex condition characterized by chronic pain and various sensory, motor, and autonomic symptoms. It involves a complex interplay of mechanisms in the nervous system, including neuroinflammation, sensitization of pain pathways, and dysfunction of the sympathetic nervous system. Antioxidants may play a role in CRPS by helping to counteract oxidative stress, which is an imbalance between the production of reactive oxygen species (ROS) and the body's antioxidant defences. CRPS involves inflammation and tissue damage, which can lead to increased ROS production and oxidative stress. Our paper represents a preliminary study on various commercially available natural-based products regarding their antioxidant effect. Several natural products with antioxidant properties, such as vitamins C and E, polyphenols, flavonoids, and botanical extracts, have shown promise in preclinical studies for their potential to alleviate pain and reduce inflammation associated with CRPS. The potential use of natural-based products with antioxidant effects for mitigating CRPS symptoms is still an area of ongoing research and investigation, but nonetheless it holds promise.

Proteomic analysis of rat colonic mucosa following acupuncture treatment for irritable bowel syndrome with diarrhea

To investigate the molecular pathological mechanisms of irritable bowel syndrome with diarrhea (IBS-D) and elucidate the effects of acupuncture on IBS-D colonic mucosa protein abundance in rats, a label-free high-throughput liquid chromatography-tandem mass spectrometry (LC-MS)-based proteomics analysis was used to survey the global changes of colonic mucosa proteins between different groups. Sixteen Sprague-Dawley (SD) male rats were randomly divided into four groups: the control group (C); the IBS-D model group (M); the syndrome differentiation acupuncture group (SD) and the traditional acupuncture group (T). IBS-D model rats were obtained using the CAS (chronic acute combining stress model) method. Comparative bioinformatics analysis of the proteomic data was analyzed using MaxQuant software, Perseus software, online tools DAVID, VENNY and STRING. Functional enrichment and network analyses revealed a close relationship between IBS-D and several biological processes including energy metabolism, muscular excitation/contraction, and both traditional acupuncture and syndrome differentiation acupuncture can reverse the impairments of normal energy metabolism. Moreover, the syndrome differentiation acupuncture can regulate the protein cluster relating inflammation, wound repair and cell protection against oxidative stress which is associated with acupuncture analgesic effect. Differentially expressed proteins Atp5a1 and Bpnt1 were selected as representative proteins and subjected to western blotting. In conclusion, our study provides further insight into the pathological and molecular mechanisms of IBS-D and acupuncture treatments, and serves as an experimental basis for clinical applications.

Nrf2 Activation Mediates Antiallodynic Effect of Electroacupuncture on a Rat Model of Complex Regional Pain Syndrome Type-I through Reducing Local Oxidative Stress and Inflammation

Complex regional pain syndrome type-I (CRPS-I) represents a type of neurovascular condition featured by severe pain in affected extremities. Few treatments have proven effective for CRPS-I. Electroacupuncture (EA) is an effective therapy for pain relief. We explored the mechanism through which EA ameliorates pain in a rat CRPS-I model. The chronic postischemic pain (CPIP) model was established using Sprague-Dawley rats to mimic CRPS-I. We found that oxidative stress-related biological process was among the predominant biological processes in affected hindpaw of CPIP rats. Oxidative stress occurred primarily in local hindpaw but not in the spinal cord or serum of model rats. Antioxidant N-acetyl cysteine (NAC) attenuated mechanical allodynia and spinal glia overactivation in CPIP model rats, whereas locally increasing oxidative stress is sufficient to induce chronic pain and spinal glia overactivation in naive rats. EA exerted remarkable antiallodynia on CPIP rats by reducing local oxidative stress via enhancing nuclear factor erythroid 2-related factor 2 (Nrf2) expression. Pharmacological blocking Nrf2 abolished antioxidative and antiallodynic effects of EA. EA reduced spinal glia overactivation, attenuated the upregulation of inflammatory cytokines, reduced the enhanced TRPA1 channel activity in dorsal root ganglion neurons innervating the hindpaws, and improved blood flow dysfunction in hindpaws of CPIP rats, all of which were mimicked by NAC treatment. Thus, we identified local oxidative injury as an important contributor to pathogenesis of animal CRPS-I model. EA targets local oxidative injury by enhancing endogenous Nrf2-mediated antioxidative mechanism to relieve pain and inflammation. Our study indicates EA can be an alternative option for CRPS-I management.

Serum inflammatory and oxidative stress biomarkers levels are associated with pain intensity, pressure pain threshold and quality of life in myofascial pain syndrome

OBJECTIVES

We aimed to determine the serum concentrations of some inflammatory and oxidative stress biomarkers in relation with pain intensity and quality of life in patients with myofascial pain syndrome (MPS) compared to healthy controls. This study is a case-control study. The participants were selected from MPS patients who referred to rehabilitation outpatient clinics of the Tabriz University of Medical Sciences, Iran.

RESULTS

Serum hs-CRP (4.68 ± 4.36 vs. 2.92 ± 4.55 g/mlµ respectively, p = 0.011), phospholipase A2 (PLA2) (6.81 ± 2.22 vs. 4.73 ± 2.97 pg/ml respectively, p < 0.001) and malondialdehyde (MDA) (2.63 ± 0.71 vs. 1.98 ± 0.90 nmol/ml respectively, p < 0.001) levels were significantly higher and serum total antioxidant capacity (TAC) (2.46 ± 0.49 vs. 2.83 ± 0.82 mmol/L respectively, p = 0.011) and superoxide dismutase (SOD) (78.89 ± 37.93 vs. 154.25 ± 115.93 U/ml respectively, p < 0.001) levels were significantly lower in the MPS patients compared to healthy controls. Serum high-sensitivity C-reactive protein (hs-CRP) level was significantly and positively associated with resting (r = 0.349, p = 0.019), activity (r = 0.295, p = 0.049) and night pain (r = 0.304, p = 0.043) intensities, pressure pain threshold (PPT) (r = 0.210, p = 0.047) and pain duration (r = 0.283, p = 0.007). Serum TAC level was significantly and negatively associated with resting pain intensity (r = -0.312, p = 0.037). Some scales and subscales of quality of life were positively correlated with serum TAC level and negatively associated with serum hs-CRP and PLA2 levels.

Oxidative Stress Contributes to Fracture/Cast-Induced Inflammation and Pain in a Rat Model of Complex Regional Pain Syndrome

Clinical evidence suggests that vitamin C (Vit C) may protect against the development of complex regional pain syndrome (CRPS) after fracture or surgery. Tibia fracture followed by 4 weeks of cast immobilization (fracture/cast) in rats results in nociceptive, vascular, and bone changes resembling clinical CRPS. In this study, fracture/cast rats were treated with the oxidative stress inhibitors Vit C, N-acetyl cysteine, or 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl to examine their effects on CRPS-related nociceptive and vascular changes. Administration of these agents significantly reduced fracture/cast-induced cutaneous allodynia by 64 to 78%, muscle hyperalgesia by 34 to 40%, and hind limb unweighting by 48 to 89%. Treatments with Vit C and N-acetyl cysteine reduced the oxidative stress markers malondialdehyde in the skin, muscle, and sciatic nerve, and lactate in the gastrocnemius muscle of the fracture/cast limb. Furthermore, Vit C treatment inhibited the post-fracture upregulation of substance P and calcitonin gene-related peptide in the sciatic nerve and the increased expression of the pain-related inflammatory mediators, including interleukin (IL)-6, and nerve growth factor in the skin and IL-1β, and IL-6 in the muscle of the post-fracture/cast limb. These data suggest that oxidative stress may contribute to the nociceptive features of the rat CRPS model.

PERSPECTIVE

Vit C reduced the CRPS-like signs, oxidative stress, and the upregulation of neuropeptide production and inflammatory mediators observed after tibia fracture and casting in rats. Limiting oxidative stress by use of Vit C or alternative strategies could reduce the risk of developing CRPS after surgery or other forms of trauma.

The effectiveness of transcutaneous electrical nerve stimulation in the management of patients with complex regional pain syndrome: A randomized, double-blinded, placebo-controlled prospective study

OBJECTIVE

To investigate the effect of transcutaneous electrical nerve stimulation (TENS) on clinical recovery in the management of patients with complex regional pain syndrome Type I (CRPS Type I).

MATERIAL AND METHOD

The study included 30 patients with stage 1 and 2 CRPS Type I in the upper extremities. The patients were randomly assigned into 2 groups, group 1 (n= 15) received conventional TENS therapy for 20 minutes, and group 2 (n= 15) received sham TENS therapy. The standard physical therapy program, which included contrast bath for 20 minutes; whirlpool bath for 15 minutes; assisted active and passive range of motion, and static stretching exercises up to the pain threshold, was also conducted in both groups. Therapy was scheduled for 15 sessions. A visual analogue scale (VAS) was used to assess spontaneous pain. The Leeds Assessment of Neuropathic Signs and Symptoms (LANSS) scale and the Douleur Neuropathique en 4 Questions (DN-4) were used to assess neuropathic pain. In addition, range of motion (ROM) was measured using a goniometer and volumetric measurements were taken to assess edema. Functional capacity was assessed using a hand dynamometer and the Duruöz Hand Index (DHI). All measurements were performed at baseline and after therapy.

RESULTS

Significant improvements were achieved in spontaneous and neuropathic pain scores, edema, ROM, and functional capacity in both groups (p< 0.05). However, improvement was found to be significantly greater in group 1 regarding pain intensity, neuropathic pain assessed using LANNS, edema, and in the 2nd-3rd finger ROM measurements (p< 0.05). No significant difference was detected between groups regarding improvements in 4th-5th finger and wrist ROM measurements, grip strength, and DN4 and DHI scores (p> 0.05).

CONCLUSION

The addition of TENS to the physical therapy program was seen to make a significant contribution to clinical recovery in CRPS Type 1.

A Novel Compound Analgesic Cream (Ketamine, Pentoxifylline, Clonidine, DMSO) for Complex Regional Pain Syndrome Patients

BACKGROUND

Evidence suggests that complex regional pain syndrome (CRPS) is a manifestation of microvascular dysfunction. Topical combinations of α2-adrenergic receptor agonists or nitric oxide donors with phosphodiesterase or phosphatidic acid inhibitors formulated to treat microvascular dysfunction have been shown to reduce allodynia in a rat model of CRPS-I. Driven by these findings, we assessed the outcomes of CRPS patients treated with a compound analgesic cream (CAC) consisting of ketamine 10%, pentoxifylline 6%, clonidine 0.2%, and dimethyl sulfoxide 6% to 10%.

METHODS

An audit was conducted on 13 CRPS patients who trialed the CAC. A detailed report was compiled for each patient which comprised baseline characteristics, including CRPS description, previous treatments, and pain scores (numerical pain rating scale; 0 to 10). Recorded outcomes consisted of pain scores, descriptive outcomes, and concurrent medications/treatments, for which basic analysis was performed to determine the effectiveness of the CAC. Case reports are presented for 3 patients with varying outcomes.

RESULTS

Nine patients (69%) reported pain/symptom reduction (4.4 ± 2.1 vs. 6.3 ± 1.9) with use of the CAC. Six patients reported sustained benefits after 2 months of CAC use, and 2 patients reported complete resolution of pain/symptoms: one had early CRPS-I and the other received a partial CRPS diagnosis. An otherwise medication refractory and intolerant patient found partial benefit with the CAC.

CONCLUSIONS

These results demonstrate promise for this topical combination as a useful treatment in multimodal therapy for patients with CRPS, with the potential to resolve pain/symptoms in early CRPS patients.

Variation in hydration status within the normative range is associated with urinary biomarkers of systemic oxidative stress in Guatemalan preschool children

BACKGROUND

Researchers have increasingly sought noninvasive methods to determine health and nutritional status in humans. Easy and painless to collect, human urine is a source of noninvasive biomarkers.

OBJECTIVE

We aimed to explore the relation between systemic oxidative stress biomarkers excreted in urine and urinary osmolality (Uosm).

DESIGN

The current trial was a descriptive, cross-sectional study. We collected seventy-eight samples of 24-h urine in preschoolers who were attending daycare centers in the Western Highlands province of Quetzaltenango, Guatemala. After we measured the total urine volume (Uvol), the aliquot was stored for the later determination of Uosm as a hydration biomarker and to measure 15-isoprostane F2t (F2-Iso) and 8-hydroxydeoxyguanosine (8-OHdG) as biomarkers of cellular oxidation with the use of ELISA assay kits in Spain. Descriptive statistics and linear [Spearman rank-order (rs)] and nonlinear (goodness-of-fit) correlations were performed.

RESULTS

Twenty-four hour Uvols ranged from 65 to 1670 mL, whereas the Uosm varied between 115 and 1102 mOsm/kg. With respect to oxidative biomarkers, the 24-h urinary output of F2-Iso and 8-OHdG had median values of 748 and 2793 ng/d, respectively. The Uvol correlated inversely and significantly with the concentrations of both oxidative biomarkers (F2-Iso rs = -0.603, P < 0.001; 8-OHdG rs = -0.433, P < 0.001), whereas the Uosm was correlated in a direct manner (F2-Iso rs = 0.541, P < 0.001; 8-OHdG rs = 0.782, P < 0.001) when analyzed as a concentration. Associations were weaker when they were analyzed as the total 24-h production.

CONCLUSIONS

Preschool children from the Western Highlands of Guatemala show strong correlations between hydration status measured through the use of Uosm and biomarkers of oxidative stress in urine. Thus, a relatively superior hydration status is associated with a quantitative reduction in urinary excretion of systemic oxidation products. This trial was registered at clinicaltrials.gov as NCT02203890.

Effect of oral taurine on morbidity and mortality in elderly hip fracture patients: a randomized trial

Hip fracture patients represent a large part of the elderly surgical population and face severe postoperative morbidity and excessive mortality compared to adult surgical hip fracture patients. Low antioxidant status and taurine deficiency is common in the elderly, and may negatively affect postoperative outcome. We hypothesized that taurine, an antioxidant, could improve clinical outcome in the elderly hip fracture patient. A double blind randomized, placebo controlled, clinical trial was conducted on elderly hip fracture patients. Supplementation started after admission and before surgery up to the sixth postoperative day. Markers of oxidative status were measured during hospitalization, and postoperative outcome was monitored for one year after surgery. Taurine supplementation did not improve in-hospital morbidity, medical comorbidities during the first year, or mortality during the first year. Taurine supplementation lowered postoperative oxidative stress, as shown by lower urinary 8-hydroxy-2-deoxyguanosine levels (Generalized estimating equations (GEE) analysis average difference over time; regression coefficient (Beta): −0.54; 95% CI: −1.08–−0.01; p = 0.04), blunted plasma malondialdehyde response (Beta: 1.58; 95% CI: 0.00–3.15; p = 0.05) and a trend towards lower lactate to pyruvate ratio (Beta: −1.10; 95% CI: −2.33–0.12; p = 0.08). We concluded that peri-operative taurine supplementation attenuated postoperative oxidative stress in elderly hip fracture patients, but did not improve postoperative morbidity and mortality.

[Complex regional pain syndrome: A current review]

Complex regional pain syndrome (CRPS) may develop following fractures, limb trauma, or lesions of the peripheral or central nervous system. The clinical picture consists of a triad of symptoms including autonomic, sensory, and motor dysfunction. Diagnosis is based on clinical signs and symptoms according to the Budapest criteria. Therapy is based on an individual and multidisciplinary approach. Distinct methods of physical therapy and pharmacological strategies are the mainstay of therapy. Pharmacotherapy is based on individual symptoms and includes steroids, free radical scavengers, treatment of neuropathic pain, and agents interfering with bone metabolism. In some cases invasive methods may be considered.

Aberrant free radical biology is a unifying theme in the etiology and pathogenesis of major human diseases

The seemingly disparate areas of oxygen toxicity, radiation exposure, and aging are now recognized to share a common feature—the aberrant production and/or removal of biologically derived free radicals and other reactive oxygen and nitrogen species (ROS/RNS). Advances in our understanding of the effects of free radicals in biology and medicine have been, and continue to be, actively translated into clinically tractable diagnostic and therapeutic applications. This issue is dedicated to recent advances, both basic discoveries and clinical applications, in the field of free radicals in biology and medicine. As more is understood about the proximal biological targets of aberrantly produced or removed reactive species, their sensors, and effectors of compensatory response, a great deal more will be learned about the commonalities in mechanisms underlying seemingly disparate disease states. Together with this deeper understanding, opportunities will arise to devise rational therapeutic interventions to decrease the incidence and severity of these diseases and positively impact the human healthspan.