Fluid Nitric Oxide Research Articles

The adjunctive effect of subgingival application of probiotics versus spirulina to nonsurgical treatment of stage II grade B periodontitis: a randomized controlled clinical trial

Abstract Aim The use of natural remedies as local drug delivery has grown recently since they are generally safe and have shown promising outcomes in the management of periodontitis. The purpose of this study was to evaluate the effectiveness of spirulina gel and probiotics as supplements for scaling and root planing (SRP). Patients and methods Thirty individuals with periodontitis (stage II, grade B) were divided into three groups at random: group I (GI) received a subgingival application of probiotic (Lactobacillus reuteri) suspension after SRP. Group II (GII) had SRP, then spirulina gel was applied. Group III (GIII) was used as a control that received SRP and placebo gel using a blunt syringe at baseline, 1, 2, and 4 weeks. Gingival index (GI), probing pocket depth, clinical attachment level (CAL), and gingival crevicular fluid nitric oxide level were assessed at baseline, 3, and 6 months. Results Compared to the baseline value, the three treatments led to a statistically significant decrease in GI, probing pocket depth, and clinical attachment level gain after 3 and 6 months (P < 0.05). Comparing the groups to each other’s, there were significant differences between them, whereas both GI and GII showed statistically significant differences when compared to GIII (the control group). All treatment modalities resulted in a statistically significant reduction in the gingival crevicular fluid level of NO, but group II showed the best effect on the inhibition of the nitric oxide level. Conclusion Local application of probiotics and spirulina is safe and effective as adjunctive treatment to SRP in the treatment of stage II, grade B periodontitis.

Cerebrospinal Fluid Nitric Oxide Synthase is a Potential Mediator Between Cigarette Smoke Exposure and Sleep Disorders.

Cigarette smoking and low peripheral nitric oxide synthase (NOS) levels are strongly associated with sleep disorders. However, whether cerebrospinal fluid (CSF) NOS relates to sleep disorders and whether CSF NOS mediates the relationship between cigarette smoking and sleep disorders is unclear. We measured CSF levels of total NOS (tNOS) and its isoforms (inducible NOS [iNOS] and constitutive NOS [cNOS]) in 191 Chinese male subjects. We applied the Pittsburgh Sleep Quality Index (PSQI). The PSQI scores of active smokers were significantly higher than those of non-smokers, while CSF tNOS, iNOS, and cNOS were significantly lower (all p < 0.001). CSF tNOS, iNOS, and cNOS were negatively associated with PSQI scores in the general population (all p < 0.001). Mediation analysis suggested that CSF tNOS, iNOS, and cNOS mediate the relationship between smoking and PSQI scores, and the indirect effect accounted for 78.93%, 66.29%, and 81.65% of the total effect, respectively. Cigarette smoking is associated with sleep disorders. Active smokers had significantly lower CSF levels of tNOS, iNOS, and cNOS. Furthermore, tNOS, iNOS, and cNOS mediate the relationship between cigarette smoking and sleep quality. This study provides insights into how cigarette smoke affects sleep disorders.

Cerebrospinal Fluid Nitric Oxide as a diagnostic inflammatory Marker of Central Nervous System Inflammatory Condition

Cerebrospinal Fluid Nitric Oxide as a diagnostic inflammatory Marker of Central Nervous System Inflammatory Condition

Peri-Implant Sulcular Fluid (PISF) Nitric Oxide (NO) as an Early Marker of Inflammation

Peri-Implant Sulcular Fluid (PISF) Nitric Oxide (NO) as an Early Marker of Inflammation

Intra-Articular Injection of Umbilical Cord Mesenchymal Stem Cells Loaded With Graphene Oxide Granular Lubrication Ameliorates Inflammatory Responses and Osteoporosis of the Subchondral Bone in Rabbits of Modified Papain-Induced Osteoarthritis.

AimThis study is to investigate the effects of umbilical cord mesenchymal stem cells (UCMSCs) loaded with the graphene oxide (GO) granular lubrication on ameliorating inflammatory responses and osteoporosis of the subchondral bone in knee osteoarthritis (KOA) animal models.MethodsThe KOA animal models were established using modified papain joint injection. 24 male New Zealand rabbits were classified into the blank control group, GO group, UCMSCs group, and GO + UCMSCs group, respectively. The concentration in serum and articular fluid nitric oxide (NO), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), type II collagen (COL-II), and glycosaminoglycan (GAG) was detected using ELISA, followed by the dissection of femoral condyles and staining of HE and Micro-CT for observation via the microscope.ResultsGO granular lubrication and UCMSCs repaired the KOA animal models. NO, IL-6, TNF-α, GAG, and COL-II showed optimal improvement performance in the GO + UCMSCs group, with statistical significance in contrast to the blank group (P <0.01). Whereas, there was a great difference in levels of inflammatory factors in serum and joint fluid. Micro-CT scan results revealed the greatest efficacy of the GO + UCMSCs group in improving joint surface damage and subchondral bone osteoporosis. HE staining pathology for femoral condyles revealed that the cartilage repair effect in GO + UCMSCs, UCMSCs, GO, and blank groups were graded down.ConclusionUCMSCs loaded with graphene oxide granular lubrication can promote the secretion of chondrocytes, reduce the level of joint inflammation, ameliorate osteoporosis of the subchondral bone, and facilitate cartilage repair.

Levodopa-induced dyskinesias in Parkinson's disease increase cerebrospinal fluid nitric oxide metabolites' levels.

Levodopa-induced dyskinesia (LID) is a common complication of Parkinson's disease (PD) therapy. Nitric oxide in the central nervous system may have a role in its pathophysiology. The present work investigates plasma and CSF levels of nitric oxide metabolites nitrite and nitrate in patients with PD, LID, and healthy control. We measured plasma and CSF nitrite and nitrate levels in patients with PD with and without LID and in healthy controls. The levels of plasma and CSF nitrite and nitrate were measured by ozone-based chemiluminescence. Sixty-seven participants were enrolled. CSF nitrite levels in patients with PD and LID were higher than in patients with PD without LID and healthy controls. CSF/plasma ratio of nitrite was higher in patients with PD and LID than in patients with PD without LID. The CSF/plasma ratio of nitrite in patients with PD and LID was higher than 1, indicating an intrathecal production of NO in patients with this motor complication. There was an increase in nitrate levels of CSF and CSF/plasma ratio of nitrate in patients with PD and LID compared to the healthy controls. Sex, age at evaluation, disease duration, and levodopa equivalent daily doses, as well as processing and storage time, did not critically influence these results. The present study demonstrated an increase in nitrite and nitrate levels in the central nervous system of patients with PD and LID. This finding strengthens the role of NO on LID pathophysiology.

Second trimester maternal serum–amniotic fluid nitric oxide and vascular endothelial growth factor levels in relation to uterine artery Doppler indices in pregnancies with normal outcome

The aim of the present study was to explore the possible relations of maternal serum and amniotic fluid nitric oxide (NO) and of vascular endothelial growth factor A (VEGF-A) concentrations with uterine artery Doppler indices (UtADs) in a healthy second trimester obstetric population. In this regard, the levels of NO and VEGF-A were measured in maternal sera and the amniotic fluid samples were in 36 subjects who were in their early second trimester of pregnancy. The mean levels for VEGF-A were 110.3 ± 31.5 pg/ml in maternal serum and 149.6 ± 31.3 pg/ml in amniotic fluid. Mean levels for NO were 5.7 ± 4.7 µmol in maternal serum and 12.9 ± 3.4 µmol in amniotic fluid. UtADs were measured concurrently with the sample collections. The mean value for uterine artery pulsatility index (PI) was 1.3 ± 0.4. The measurements were then analysed for possible correlations, whereby no correlation was found between UtAD and maternal serum levels of either molecule (p = .828 and p = .662 for VEGF-A and NO, respectively). However, a positive correlation was found between the NO levels in the amniotic fluid compartment and UtAD (r = 0.432, p = .009 for PI). Therefore, a correlation of UtAD with amniotic fluid NO can be expected in pregnancies with a normal outcome.Impact StatementWhat is already known on this subject? Nitric oxide (NO) and vascular endothelial growth factor A (VEGF-A) are important vasoactive molecules that play significant roles in early angiogenesis and placentation.What the results of this study add? There is a positive correlation between the amniotic fluid NO levels and the uterine artery Doppler indices (UtADs) in the second trimester of pregnancies with normal outcomes.What the implications are of these findings for clinical practice and/or future research? A correlation between amniotic fluid NO levels and UtAD may indicate a normal trophoblastic invasion. Disturbance of this balance may be expected in certain adverse pregnancy outcomes. Additional studies are needed to further explore the molecular signs of early abnormal placentation and their clinical reflection.

Success in the acquisition of Bombyx mori sperm motility is influenced by the extracellular production of nitric oxide (NO) in the presence of seminal fluid nitric oxide synthase (NOS)

A trypsin-like protease called initiatorin is known to initiate sperm motility in the silkworm, Bombyx mori, but little is known about the signaling events leading to sperm flagellar beating. The aim of this study was to investigate whether this mechanism of sperm motility activation involves the signaling transmitter nitric oxide (NO). NO is produced from the amino acid L-arginine by the enzyme action of nitric oxide synthase (NOS; EC 1.14.13.39). Simple treatment of quiescent sperm with an NO donor (SNAP or NOC7) in vitro did not lead to activation of motility. Nevertheless, initiatorin- or trypsin-induced motility was blocked by pretreatment of sperm with either the NOS inhibitor L-NAME or NO scavenger carboxy-PTIO. These observations suggested that NO may play important physiological roles in the acquisition of sperm motility under the in vitro condition used here. Then, we investigated whether NO synthesis would occur in the spermatophore, a capsule containing spermatozoa that is created by the contents of various male reproductive glands and is the site of sperm maturation. The amounts of NO2− and NO3−, stable metabolites of NO, reached maximum values after enclosure in the spermatophore, a time when apyrene spermatozoa acquire vigorous motility. Moreover, RT-PCR and Western blotting analyses of NOS indicated that it is abundantly expressed in glandula (g.) lacteola of the virgin male ejaculatory duct, from which it is secreted to the seminal fluid and transferred to the female during mating. Previous studies demonstrated that free L-arginine is supplied de novo by a specific proteolytic reaction in which initiatorin participates during spermatophore formation (Osanai et al., 1987c). Based on these results, it can be presumed that the mixing of seminal fluid contents from each male reproductive organ during ejaculation induced NO production outside of the spermatid, and exogenous NO stimulated a signaling pathway involved in the activation of silkworm apyrene sperm.

Amniotic fluid total antioxidant capacity and nitric oxide in emergency cerclage

Objective: Nitric oxide (NO) is one of the reactive oxygen species (ROS) that has been associated with inflammation. Total antioxidant capacity (TAC) neutralizes ROS. We evaluated that amniotic fluid (AF) TAC and NO correlate with the outcome of emergency cerclage.Methods: Thirty-six women with cervical dilatation (≥2 cm) and bulging membranes between 16 and 24 weeks underwent emergency cerclage. Sixty-seven women between 16 and 24 weeks who had amniocentesis for chromosomal test provided control samples. AF samples were tested for TAC, and NO, and then correlated with pregnancy outcome.Results: AF TAC was significantly lower in cerclage group than control group (cerclage: 92.6 mmol/L versus control: 127.2 mmol/L, p < 0.001). Higher levels of AF TAC were associated with a longer latency from cerclage to delivery (r = 0.62, p < 0.001). NO was similar between two groups (p = 0.35). The mean gestational age at delivery of control group was better than cerclage group (cerclage: 29.5 weeks versus control: 39.4 weeks, p < 0.01).Conclusion: Higher levels of AF TAC are correlated with longer prolongation days after cerclage. However, AF NO and iNOS are not different between two groups.

Nitric Oxide Metabolite Concentration in Cerebrospinal Fluid: Useful as a Prognostic Marker?

Study DesignProspective study.PurposeTo establish the significance of cerebrospinal fluid (CSF) nitric oxide metabolite (NOx) concentration in acute spinal cord injury (SCI) patients to assess the neurological severity and prognosis.Overview of LiteratureQuantitative analysis of specific biomarkers in CSF will assess neurological severity more accurately and permit the formulation of a more precise management plan.MethodsForty SCI patients represented the cases and 20 lower limb injury patients were the controls. NOx concentration in CSF was measured at week 1, 2, and 4 by Griess method. Magnetic resonance imaging (MRI, T2-weighted) done in each case to measure cord edema and neurological severity was assessed using the Frankel classification.ResultsCSF NOx concentration peaked at week 2 and declined to normal by week 4. The concentration remained normal in controls. Mean NOx concentration was directly proportional to the severity of acute SCI as correlated with cord edema seen in MRI and neurological severity assessed.ConclusionsCSF NOx concentration can be considered a specific quantitative biomarker in acute stage of SCI to predict the severity and prognosis of SCI patients.

Serum and cerebrospinal fluid excitatory amino acid, nitric oxide and cerebrospinal fluid malondialdehyde levels in West syndrome

West syndrome (WS) is an epileptic syndrome of early childhood. There have been a limited numbers of studies of cerebrospinal fluid (CSF) excitatory amino acid (EAA), nitric oxide (NO), and malondialdehyde (MDA) levels, as well as plasma levels of EAA, and NO, in WS. In this article, CSF EAA, NO, and MDA levels and plasma EAA, NO status, and a determination of the effects of antiepileptic drug therapy on these values were investigated in children with WS. Evaluation of CSF and serum EAA, NO, and MDA levels and of serum EAA and NO levels after 3 mo of antiepileptic drug therapy revealed a statistically significant decrease in CSF aspartate, glutamate, NO and MDA levels. In conclusion, the decrease in CSF MDA levels in this study is the result of both the decrease in glutamate activity and neuronal damage after controlling seizures with antiepileptic drugs.

Interleukin-1 receptor antagonist decreases cerebrospinal fluid nitric oxide levels and increases vasopressin secretion in the late phase of sepsis in rats.

The aim of this study was to analyze the effect of IL-1ra (an Interleukin-1 receptor antagonist) on sepsis-induced alterations in vasopressin (AVP) and nitric oxide (NO) levels. In addition, IL-1ra effect on the hypothalamic nitric oxide synthase (NOS) activities and survival rate was also analyzed. After Wistar rats were intracerebroventricular injected with IL-1ra (9 pmol) or vehicle (PBS 0.01 M), sepsis was induced by cecal-ligation and puncture (CLP). Blood, CSF, and hypothalamic samples were collected from different groups of rats (n = 8/group) after 4, 6, and 24 h. AVP and NO levels were greatly increased in CLP. Both total NOS and inducible NOS (iNOS) activities were also greatly increased in CLP rats. These changes in AVP, NO, and NOS were not observed in sham-operated control rats. IL-1ra administration did not alter plasma AVP levels after 4 and 6 h as compared to vehicle in CLP animals but after 24 h were significantly (P < 0.01) higher in IL-1ra-treated animals. IL-1ra administration significantly (P < 0.01) decreased NO concentration in CSF but not in plasma. Both total NOS and iNOS activities were also significantly decreased by IL-1ra at 24 h in CLP animals. Moreover, the 24 h survival rate of IL-1ra-treated rats increased by 38 % in comparison to vehicle administered animals. The central administration of IL-1ra increased AVP secretion in the late phase of sepsis which was beneficial for survival. We believe that one of the mechanisms for this effect of IL-1ra is through reduction of NO concentration in CSF and hence lower hypothalamic iNOS activities in the septic rats.

Cerebrospinal fluid nitric oxide metabolite levels as a biomarker in severe traumatic brain injury

Nitric oxide has a definitive role in the complex pathophysiology of traumatc brain injury (TBI). This prospective cohort study investigated the changes in nitric oxide metabolite (NOx) levels in cerebrospinal fluid (CSF) and their correlation with factors associated with severity and prognosis after severe TBI. NOx levels were measured in CSF obtained via ventriculostomy in 44 adult patients admitted after severe TBI (Glasgow Coma Scale ≤ 8/15). The overall mean level of CSF NOx in the study population was 7.40 ± 1.59 μmol/L. Levels of CSF NOx were found to be significantly higher in subgroups of patients with poorer outcome measured by Glasgow Outcome Scale score (p < 0.042), in patients with high intracranial pressure (ICP) readings (p < 0.027) and in those with higher Marshall computed tomography (CT) grading scores (p < 0.026). Simple logistic regression demonstrated that CSF NOx levels were a significant predictor of ICP (b = 0.493, 95%CI: 1.03, 2.58, p = 0.033). A patient with 1 μmol/L increase in NOx level had 1.6 times the odds to have an ICP ≥ 20 mmHg when other confounders were not adjusted. NOx level is also a significant predictor of Marshall CT grading (b = 0.473, 95%CI: 1.02, 2.50, p = 0.037). A patient with 1 μmol/L increase in NOx level had 1.6 times the odds to have a high Marshall grade when other confounders were not adjusted. It can be concluded that CSF NOx levels may serve as a potentially useful biomarker in severe TBI given its significant association with ICP readings as well as Marshall CT grading.

Effect of IL-1 receptor antagonist on the cerebrospinal fluid nitric oxide concentrations during experimental polymicrobial sepsis in rats

Effect of IL-1 receptor antagonist on the cerebrospinal fluid nitric oxide concentrations during experimental polymicrobial sepsis in rats

Minocycline and fluorocitrate suppress spinal nociceptive signaling in intrathecal IL‐1β–induced thermal hyperalgesic rats

We previously demonstrated that intrathecal IL-1β caused thermal hyperalgesia in rats. This study was conducted to examine the effects and cellular mechanisms of glial inhibitors on IL-1β-induced nociception in rats. The effects of minocycline (20 μg), fluorocitrate (1 nmol), and SB203580 (5 μg) on IL-1β (100 ng) treatment in rats were measured by nociceptive behaviors, western blotting of p38 mitogen-activated protein kinase (MAPK) and inducible nitric oxide synthase (iNOS) expression, cerebrospinal fluid nitric oxide (NO) levels, and immunohistochemical analyses. The results demonstrated that intrathecal IL-1β activated microglia and astrocytes, but not neurons, in the dorsal horn of the lumbar spinal cord, as evidenced by morphological changes and increased immunoreactivity, phosphorylated p38 (P-p38) MAPK, and iNOS expression; the activation of microglia and astrocytes peaked at 30 min and lasted for 6 h. The immunoreactivities of microglia and astrocytes were significantly increased at 30 min (6.6- and 2.7-fold, respectively) and 6 h (3.3- and 4.0-fold, respectively) following IL-1β injection, as compared with saline controls at 30 min (all P < 0.01). IL-1β induced P-p38 MAPK and iNOS expression predominantly in microglia and less in astrocytes. Minocycline, fluorocitrate, or SB203580 pretreatment suppressed this IL-1β-upregulated P-p38 MAPK mainly in microglia and iNOS mainly in astrocytes; minocycline exhibited the most potent effect. Minocycline and fluorocitrate pretreatment abrogated IL-1β-induced NO release and thermal hyperalgesia in rats. In conclusion, minocycline, fluorocitrate, and SB203580 effectively suppressed the IL-1β-induced central sensitization and hyperalgesia in rats.

High-risk human papillomavirus-induced expression of endothelial and inducible nitric oxide synthase in human uterine cervix

Introduction. Levels of nitric oxide metabolites are elevated in the cervical fluid of women with high-risk human papillomavirus (hrHPV). To elucidate the origin of this elevation we studied the cervical expression and localization of endothelial and inducible nitric oxide synthases (eNOS, iNOS) in women. Material and methods. Expression of eNOS and iNOS was studied by Western blotting in the uterine cervixes of 86 women with (n = 41) and without (n = 45) hrHPV infection. The localization of eNOS and iNOS in cervical cells was studied by immunohistochemistry in 32 randomly selected women. Results. Expression of eNOS and iNOS (in mean [95% CI] density units relative to actin) was higher in women with hrHPV versus those without (eNOS: 33.8 [22.5–45.1] versus 20.2 [6.1–34.3], P = 0.007; iNOS: 12.0 [7.1–16.9]) versus 5.6 [2.0–9.2], P = 0.003). Smoking reduced 64% eNOS (P = 0.001) and 68% iNOS (P = 0.008) in women with hrHPV. Endothelial NOS was localized in the vascular endothelium, while iNOS was present in basal squamous epithelial cells. Low-grade histological lesions were accompanied by elevated expression of both eNOS and iNOS. Conclusions. High-risk HPV-associated elevation in cervical fluid nitric oxide metabolites results from both eNOS and iNOS stimulation. However, smoking seems to suppress this stimulation in hrHPV-infected women.

Nitric oxide and superoxide dismutase in rheumatoid arthritis: Correlation with disease activity

Aim: To analyse serum and synovial fluid nitric oxide (NO) concentrations and erythrocyte CuZn superoxide dismutase (SOD) activity in rheumatoid arthritis (RA) patients and to determine the importance of imflammatory markers in reflect disease activity. Methods: 20 RA patients and 15 healthy controls were included. NO level was determined spectrophotometrically by the Griess reaction and CuZn SOD activity by the method of Sun et al. Results: Erythrocyte sedimentation rate (ESR), C-reactive protein and leukocyte levels were determined as inflammatory markers. Significantly higher ESR (p<0.001) and leukocyte levels (p<0.01) and serum and synovial fluid NO levels (p<0.01, p<0.05) and lower CuZn SOD activity (p<0.05) were observed in RA patients. Classification of RA patients according to disease activity score (DAS) revealed significantly higher synovial fluid NO level (p<0.05) and lower CuZn SOD activity (p<0.05) in RA patients with DAS≥2.7. Conclusions: Increased serum and synovial fluid NO levels and decreased CuZn SOD activity up-regulated inflammatory response are observed in RA patients.

Periodontal Nitric Oxide Pathway Alteration Due to Precompetition Anxiety in Handball Players

Psychologic and physical stress is known to be related with periodontal disorders. The objective of this study is to investigate salivary and gingival crevicular fluid (GCF) nitric oxide (NO) metabolism and its association with the periodontal reaction to precompetition anxiety in competitive athletes. A total of 18 elite male handball players participated in this study. The anxiety level of participants was determined by using a competitive state anxiety inventory-2 (CSAI-2). Periodontal clinical measurements, saliva, and GCF samples were obtained before the application of the CSAI-2 during the half-season break and just before the league championship match. NO-level, arginase, and NO synthase (NOS) activities were analyzed in saliva samples; NO and basic fibroblast growth factor (FGF-b) levels were analyzed in GCF samples. The CSAI-2 was significantly different between the two evaluation time points. GCF NO and FGF-b levels increased before the championship match, whereas saliva levels did not change. The plaque index and gingival index (GI) increased at the evaluation just before the championship match. The difference in the GI was statistically significant. The competitive stress of athletes may lead to a gingival/periodontal disturbance accompanied by an altered NO metabolism in saliva and GCF.

The Prognostic Value of Brain Extracellular Fluid Nitric Oxide Metabolites After Traumatic Brain Injury

Nitric oxide (NO) is a compound with both protective and damaging effects on neurons. Quantification of NO metabolites in humans is limited by sample contamination with blood. In vivo cerebral microdialysis may offer an alternative approach as sampling of extracellular fluid (ECF) adjacent to neurons becomes possible. We investigate the prognostic value of brain ECF NO metabolites in patients with traumatic brain injury (TBI). A prospective case cohort of 195 ECF samples collected from 11 cases over 4 days following TBI was collected. Nitrate and nitrite concentrations ([NO x ]) were quantified using a vanadium-based colorimetric assay. Early ECF [NO x ] (<48 h post TBI) were significantly higher in non-survivors (median 59.2 μmol/l, n = 7) compared to survivors (23.3 μmol/l, n = 4) (P = 0.04). Late (48-96 h) ECF [NO x ] remained higher in non-survivors (47.9 μmol/l) compared to survivors (23.0 μmol/l) but this was not significant (P = 0.29). Receiver operator characteristic analysis shows an optimized cutoff level for ECF [NO x ] of 26.5 μmol/l measured <48 h post TBI for predicting non-survival (sensitivity 100%, specificity 75%). Early ECF NO x concentrations are of prognostic value after TBI. ECF NO x may be a useful biomarker for treatment trials targeted at nitric oxide metabolism.

Cervical nitric oxide release in Chlamydia trachomatis and high-risk human papillomavirus infection

To compare cervical fluid nitric oxide release in women with and without Chlamydia trachomatis and high-risk human papillomavirus infection (hrHPV). An open clinical study. University Hospital of Helsinki. Thirty-nine women with (n=21) and without C. trachomatis (n=18). Chlamydia trachomatis and/or hrHPV were studied by using specific RNA- and DNA-based tests. Levels of cervical fluid nitric oxide metabolite (NOx) were assessed by the Griess reaction. The difference in cervical fluid NOx between women with and without C. trachomatis and hrHPV. Fourteen (67%) C. trachomatis-infected women and three (17%) noninfected women had concomitant hrHPV. The level of cervical fluid NOx in women with C. trachomatis (median 37.5 μmol/l, 95% confidence interval 26.1-50.9) was higher (p=0.02) than that in C. trachomatis-noninfected women (median 19.7 μmol/L, 95% confidence interval 5.6-30.0). The presence of hrHPV did not associate with any difference in NOx levels between C. trachomatis-infected or -noninfected women. Chlamydia trachomatis was associated with increased release of nitric oxide metabolites in the uterine cervix. This stimulus was stronger than that of hrHPV, because no additional rise in NOx was seen in women with concomitant C. trachomatis and hrHPV infection.