Dermatofibrosarcoma Protuberans in Children

OPINION STATEMENT

Paediatric dermatofibrosarcoma protuberans (DFSP) is a rare soft tissue malignant tumour which displays aggressive local behaviour and has low metastatic potential. The diagnosis is often delayed as DFSP is usually mistaken for other skin conditions, particularly in the early stages of disease. DFSP tends to follow an indolent course after the initial presentation with what is often described as a "rubbery lump". As the disease progresses, the lump tends to enlarge, change colour, and exhibit a more nodular consistency. In rare cases, DFSP can present as an ulcerated exophytic lesion or a depressed area of skin, making diagnosis even more challenging. A high index of suspicion is warranted for early diagnosis, and referral to a specialist unit with expertise in both oncologic resection and reconstruction. DFSP tumours arise from the dermis and grow with finger-like projections. Therefore, in cosmetically sensitive or functionally important locations, an excision and analysis technique that assesses all excision margins is the gold standard of care. Slow Mohs technique performed with en bloc excision is a well-tolerated option for oncologic resection of the tumour. Mohs technique can also be considered but can be challenging in children for reasons explained below. As an alternative, depending on the anatomical location, tumours can be excised with a wide local excision. While an excision technique that incorporates the deep fascia with a 3-cm peripheral margin is acceptable in adults, planning of the excision margin in children should involve consideration of preoperative imaging with MRI, site of the tumour, age, and physical built of the child. Patients should be offered all treatment options considering the local outcomes, available expertise, and cost. A multidisciplinary approach and good communication between team members is crucial. Close collaboration with a pathologist who is familiar with sectioning technique that allows margin control is of paramount importance. Soft tissue reconstruction should be performed immediately after oncologic clearance, although a staged approach may be required. Adjuvant radiotherapy should be avoided in children due to the long-term risk of secondary malignancies and potential for growth disruption.

931 Deep Inferior Epigastric Perforator (DIEP) Flap: Impact of Early Drain Removal on Seroma Formation Rate and Duration of Inpatient Stay

Aim

Donor site seroma can follow deep inferior epigastric flap (DIEP) harvest. Post-surgery gradient technology (GTC) garments are worn by DIEP patients postoperatively following drain removal to reduce seroma formation. Early drain removal was considered a contributing factor to increased seroma formation rate. From June 2018 drain removal regardless of output was instigated at day two post-surgery. Prior to this, drains were removed when less than 30mls over 24 hours. We aim to assess the seroma rate post DIEP harvest with early drain removal.

Method

Retrospective review of prospectively managed database between June 2018 to May 2020. Surgical complications and length of stay in hospital were recorded.

Results

200 patients underwent DIEP flap breast reconstruction. The mean age of patients was 52 years (range 28-73). There was no significant difference in seroma complication rate between those who had drains removed on day 3 compared with day 2 ((1.02% (1/98) vs. (0.98% (1/102); p = 1). The mean length of stay in hospital for the 1st cohort was 3.86 days and for the 2nd cohort was 3.23 days. There were no complications related to drain removal.

Conclusions

Our data suggests that drain removal after 2 days postoperatively with DIEP reconstruction does not affect seroma complication rates. Moreover, it leads to a shorter hospital stay. These conclusions are in keeping with enhanced recovery protocols and an early drain removal surgical process could be advised.

1644 Trainee Perspective in Sarcoma Care

Aim

Soft tissue sarcomas (STS) are rare and aggressive tumours. Appropriate multidisciplinary management requires robust knowledge of best practice and understanding of current guidelines. Plastic surgery trainees must therefore be proficient in the assessment, investigation, and treatment of patients with STS. We aimed to evaluate trainee education, confidence, and competence in managing patients with STS.

Method

All plastic surgery trainees in Wales completed an online questionnaire and written assessment. This was designed by the lead for STS and TPD. Formal training, knowledge of national guidelines and excision margins for different types of STS and skin cancer was assessed using short answer questions. A five-point Likert scale was used to assess trainee confidence in STS and skin cancer management and follow-up. Volume and type of teaching in sarcoma and skin cancer was also quantified.

Results

Trainees received less sarcoma training and were less confident in STS assessment and follow-up, in comparison to skin cancer. More senior trainees or those with formal sarcoma training were more confident in skin cancer management (mean confidence rating 4.4 vs 2.2) and performed better in the written assessment of excision margins (mean score 100% vs 61.45%)

Conclusions

Trainees receive less training in sarcoma with a significant impact on their competence and confidence in sarcoma care. We believe this is consistent across the United Kingdom as evidenced by just two sarcoma webinars held during the COVID-19 pandemic. Formal national evaluation of sarcoma teaching should be carried out to inform ongoing efforts to improve educational resources on this important topic for trainees.

1607 Seeing White: Management of TIVA During Autologous Breast Reconstruction

Background

Free flap surgery has inherent risks, and the venous drainage of the Deep Inferior Epigastric Perforator (DIEP) flap is particularly vulnerable to congestion. In these cases, an algorithm for flap salvage should be followed and one of the final steps in this process is a cephalic vein transposition.

Case Report

We describe two patients undergoing mastectomy and immediate bilateral DIEP breast reconstruction, where cephalic vein transposition was required. As part of the Enhanced Recovery After Surgery (ERAS) pathway, patients are anaesthetised with a continuous propofol infusion (Total Intravenous Anaesthesia; TIVA). When the cephalic vein was identified, the propofol infusion was visible within the vein, which would have interrupted TIVA if harvested. To maintain continuous TIVA infusion, the cannula was resited prior to harvest of the cephalic vein. The cephalic vein was anastomosed to the superficial inferior epigastric vein and resolution of the venous congestion was noted.

Conclusions

These cases although rare highlight the importance of robust preoperative planning and communication between the team and preparation for all eventualities to ensure patient safety and successful outcomes. These cases highlight the potential effects vein harvesting or transposition may have on the safe and effective delivery of anaesthetic agents and other medication. We hope these cases prompt a discussion in the preoperative stage for alternate strategies for monitoring and intravenous access in response to diversions from the standard operating procedure.

Rapid redesign and effect on clinical workload of a supra-regional burns and plastic surgery service during the COVID-19 pandemic

Introduction

In March 2020, South Wales experienced the most significant COVID-19 outbreak in the UK outside of London. We share our experience of the rapid redesign and subsequent change in activity in one of the busiest supra-regional burns and plastic surgery services in the UK.

Methods

A time-matched retrospective service evaluation was completed for a 7-week “COVID-19” study period and the equivalent weeks in 2018 and 2019. The primary aim of this study was to evaluate plastic surgery theatre use and the impact of service redesign. Comparison between study periods was tested for statistical significance using two-tailed t-tests.

Results

Operation numbers reduced by 64% and total operating time by 70%. General anaesthetic cases reduced from 41% to 7% (p<0.0001), and surgery was mainly carried out in ringfenced daycase theatres. Emergency surgery decreased by 84% and elective surgery by 46%. Cancer surgery as a proportion of total elective operating increased from 51% to 96% (p<0.0001). The absolute number of cancer-related surgeries undertaken was maintained despite the pandemic.

Conclusion

Rapid development of COVID-19 SOPs minimised inpatient admissions. There was a significant decrease in operating while maintaining emergency and cancer surgery. Our ringfenced local anaesthetic Plastic Surgery Treatment Centre was essential in delivering a service. COVID-19 acted as a catalyst for service innovations and the uptake of activities such as telemedicine, virtual MDTs, and online webinars. Our experiences support the need for a core burns and plastic service during a pandemic, and show that the service can be effectively redesigned at speed.

Preoperative versus Post-operative Radiotherapy for Extremity Soft tissue Sarcoma: a Systematic Review and Meta-analysis of Long-term Survival

BACKGROUND

The role of perioperative radiotherapy in the management of resectable extremity soft tissue sarcoma (ESTS) is widely recognised for local tumour control, wound complications (WC) and long-term function. However, debate continues regarding its implications on long-term survival. This study aimed to determine whether the timing of perioperative radiotherapy affects long-term survival outcomes in adults with ESTS.

METHODS

A systematic literature search of MEDLINE, EMBASE, Web of Science and Cochrane was performed. The primary outcome measure was the pooled hazard ratio (HR) at 95% confidence intervals. Secondary outcomes and subgroup analyses were presented as cumulative odds ratios (OR). A random-effects, generic inverse variance method and sensitivity analysis were performed to minimise heterogeneity.

RESULTS

Six studies (n = 4192 patients) were identified. Time-to-event analysis demonstrated a statistically significant advantage in post-operative radiotherapy for overall survival (HR 1.15 and p = 0.05). Combined HRs for disease-free (1.25 and p = 0.22) and disease-specific (1.06 and p = 0.43) survival also favoured post-operative radiotherapy but did not achieve statistical significance. Post-operative radiotherapy was shown to confer an overall (OR 1.19 and p = 0.01), disease-free (OR 1.19 and p = 0.01) and disease-specific (OR 1.19 and p = 0.01) survival advantage on subgroup analysis. This survival benefit was best observed at three years in the disease-free survival comparison (OR 1.55 and p = 0.003). Preoperative radiotherapy was associated with more WC (OR 2.74 and p<0.00001).

CONCLUSIONS

Pooled analysis of published literature suggests that post-operative radiotherapy confers a significant long-term survival advantage with fewer WC. Further large multicentre randomised controlled trials with long-term follow-up are required to determine the optimal perioperative radiotherapy regime in adult ESTS.

Bespoke regional blocks for axillary sentinel node biopsy

INTRODUCTION

Axillary sentinel node biopsy for melanoma is routinely performed under general anaesthesia. Emerging evidence has shown general anaesthetics are associated with increased mortality in the context of the COVID-19 pandemic. In the interest of patient safety, we have designed a series of bespoke axillary regional blocks enabling surgeons to remove nodes up to and including level III without the need for a general anaesthetic. The aim of this study was to assess the feasibility of performing axillary sentinel node biopsy under such blocks.

METHODS

Approval was granted by the Joint Study Review Committee on behalf of the Research and Ethics Department. Ten consecutive patients having axillary sentinel node biopsy for melanoma were included in this prospective study. Patients completed a Quality of Recovery-15 (QoR15) questionnaire preoperatively and 24 h postoperatively.

DISCUSSION

One patient had a positive sentinel node, the remining were negative. A significant reduction in time spent in hospital post-operatively (p = 0.0008) was observed. QoR15 patient reported outcome measures demonstrated high levels of satisfaction evidenced by lack of statistical difference between pre and post-operative scores (p = 0.0118). 80% of patients were happy to have a regional block and 90% were happy to attend hospital during the pandemic.

CONCLUSION

ASNB under regional block is safe, negates risks associated with performing GAs during the COVID-19 pandemic and facilitates quicker theatre turnover and discharge from hospital. Collaboration between anaesthetic and surgical teams has enabled this change in practice. There is a learning curve with both patient selection, education and development of technique.

Seeing White: Management of TIVA during autologous breast reconstruction

Total IntraVenous Anaesthesia is frequently the anaesthetic of choice for enhanced recovery after surgery pathways during breast reconstruction free flap surgery. This relies upon the continuous intravenous infusion of propofol. We describe our experience of two patients where augmentation of a venously congested DIEP flap with a cephalic vein transposition procedure, risked interruption of the intravenous delivery of anaesthesia to the patient. We also share our steps taken to mitigate this risk going forward.

Personal protective equipment for surgeons during COVID-19 pandemic: systematic review of availability, usage and rationing

BACKGROUND

Surgeons need guidance regarding appropriate personal protective equipment (PPE) during the COVID-19 pandemic based on scientific evidence rather than availability. The aim of this article is to inform surgeons of appropriate PPE requirements, and to discuss usage, availability, rationing and future solutions.

METHODS

A systematic review was undertaken in accordance with PRISMA guidelines using MEDLINE, Embase and WHO COVID-19 databases. Newspaper and internet article sources were identified using Nexis. The search was complemented by bibliographic secondary linkage. The findings were analysed alongside guidelines from the WHO, Public Health England, the Royal College of Surgeons and specialty associations.

RESULTS

Of a total 1329 articles identified, 95 studies met the inclusion criteria. Recommendations made by the WHO regarding the use of PPE in the COVID-19 pandemic have evolved alongside emerging evidence. Medical resources including PPE have been rapidly overwhelmed. There has been a global effort to overcome this by combining the most effective use of existing PPE with innovative strategies to produce more. Practical advice on all aspects of PPE is detailed in this systematic review.

CONCLUSION

Although there is a need to balance limited supplies with staff and patient safety, this should not leave surgeons treating patients with inadequate PPE.

Use of a Fascia Lata Autograft to Reconstruct a Large Triceps Tendon Defect After En-Bloc Resection of a Soft-Tissue Sarcoma: A Case Report

CASE

In this report, we present the case of a patient undergoing en-bloc resection of a large triceps soft-tissue sarcoma, requiring reconstruction of the triceps tendon including its distal insertion. We describe a surgical technique using fascia lata (FL) autograft to reconstruct the patient's extensor mechanism with long-term follow-up and functional results.

CONCLUSIONS

FL autograft is a viable option for reconstruction of large tendinous defects. It is simple and straightforward to harvest, inexpensive when compared with alternatives, with many potential applications.

Abstract P1-03-05: Not presented

This abstract was not presented at the symposium.

Abstract P5-05-02: NEDD9 promotes breast cancer metastasis by regulating mitochondrial functions

NEDD9 has been characterized as a metastasis-promoting gene in various cancer cells including breast. We previously reported that NEDD9 promotes malignant phenotypes of breast cancer cells through distinct and non-overlapped domains. For example, the FAT (Focal Adhesion Targeting) domain of NEDD9 promotes cancer cell growth, while the SH-domain facilitates cell migration. These results suggest that NEDD9 promotes tumor metastasis by enhancing dissemination and growth in the tumor-host microenvironments through distinct and non-overlapped domains. Thus, targeting functions of NEDD9 is a promising approach for breast cancer therapies.

In order to further characterize NEDD9-mediated breast cancer growth, we performed yeast-two hybrid (Y2H) screening to identify proteins that associate with the FAT domain of NEDD9. Using the FAT domain constructed in pGBKKT7 (Clonetech, CA) as a bait to screen library of human fibroblast (Clonetech, CA), we identified several proteins that associate with the domain. They are small GTPases (i.e. RAB11a and ARF4), cytoskeletal proteins (i.e. Nexilin), and cytosolic proteins (i.e. HAX-1). Among of these potential partner proteins, we focused on the interaction between NEDD9 and HAX-1 in breast cancer cells. Co-immunoprecipitation assays confirm the molecular complex of NEDD9-HAX-1 in both SK-Br3 and SUM149 cells. Importantly, p130cas, which harbors similar domain structures with NEDD9, was not precipitated with NEDD9, suggesting a specific interaction between NEDD9 and HAX-1. Given the fact of NEDD9 as a key metastasis promoting gene, these results suggest that NEDD9-HAX-1 plays a key role breast cancer metastasis by facilitating growth in microenvironments.

While the biological function are not clear at present, previous studies demonstrated that HAX-1 localizes in mitochondria in breast cancer cells, Indeed, we demonstrated that NEDD9 was found in both cytosol and mitochondria fractions in malignant breast cancer cell MDA-MB-231, but not non-metastatic HCC38. These results suggest the presence of NEDD9-HAX1 complex in mitochondria and this complex may facilitate breast cancer metastasis. In addition to HAX-1, several mitochondrial proteins such as EFG1, DCTN6, and MMADHC were found in the Y2H screening system as described above. These results suggest that NEDD9 facilitates breast cancer metastasis through regulating multiple pathways including signaling pathways and mitochondrial functions, thus serving as a promising therapeutic target for cancer patients including breast.

The view expressed in this article are those of the author and do not reflect the official policy of the Department of Defense, or U.S.Government.

Citation Format: Iida J, Dorchak J, Slavik J, Clancy R, Cutler ML, Shriver CD. NEDD9 promotes breast cancer metastasis by regulating mitochondrial functions [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-05-02.

Recurrent meningioma of the scalp after 13 years

Meningiomas represent some of the most common types of tumour of the central nervous system. They are considered benign, with ∼1 in 1000 known to metastasise. We report a case of recurrent meningioma of the scalp 13 years following craniotomy to treat the primary. The recurrent tumour of the scalp was eventually excised 5 years later and the defect closed with an anterolateral thigh free flap in a joint procedure between the neurosurgeons and plastic surgeons. Histology of the scalp lesion confirmed a WHO grade I meningioma. Although a number of explanations for recurrent scalp meningiomas exist, the precise role of isolated genetic defects in scalp meningiomas is incomplete. The scalp meningioma in this case consisted of a complex karyotype suggestive of more aggressive disease. This case emphasises that cytogenetics may play a greater role in identifying more aggressive tumours than histology alone.

Abstract P2-05-16: Tumor-associated glycans as key molecules to promote growth of triple-negative breast cancer cells

Enhanced invasion and migration into the surrounding tissues are hallmarks of the malignancy of tumor cells. To successfully metastasize, a cancer cell has to detach from the primary tumor, invade into surrounding tissues, and intravasate into blood or lymphatic vessels. These processes are composed of complex mechanisms involving tumor recognition, degradation of extracellular matrix (ECM) proteins and migration into tissue. Triple negative (TN) breast cancers are defined by a lack of expression of estrogen, progesterone, and HER2 receptors. It is widely recognized that TN breast cancers have a poorer prognosis than any other subtype of breast cancer. Given the lack of effective targeted therapies for TN breast cancer patients, understanding of the mechanisms of migration and invasion of these tumors will provide insight into developing novel approaches to lower the mortality from TN breast cancer.

Previous studies demonstrated that NEDD9 plays a key role facilitating progression and metastasis of various tumor cells including breast. We previously demonstrated that NEDD9 plays a critical role in promoting migration and growth of MDA-MB-231. In order to further characterize the mechanisms of NEDD9-mediated cancer migration and growth, we established stable cell lines expressing NEDD9 using HCC38 as a parental cell line which expresses low level of endogenous NEDD9. Microarray studies demonstrated that enzymes (CHST11, CHST15, and CSGALNACT1) involved in biosynthesis of chondroitin sulfate (CS) but not heparan sulfate (HS) were markedly upregulated in HCC38(NEDD9) compared to control HCC38(Vector) cells. These results suggest that NEDD9 regulates specific structures of tumor-associated glycans such as chondroitin sulfate. Core proteins of CD44 and Serglycin were markedly upregulated in HCC38(NEDD9) cells compared to HCC38(Vector) cells, while those of Syndecan-1, Syndecan-2, and Versican were downregulated in HCC38(NEDD9). Immunofluorescence studies using specific antibody, GD3G7, confirmed the enhanced expression of CS-E subunit in HCC38(NEDD9). Immunoprecipitation and western blotting analysis demonstrated that CS-E was attached to Serglycin and CD44 core proteins. We demonstrated that removing CS by chondroitinase ABC significantly inhibited anchorage-independent growth of HCC38(NEDD9) in methylcellulose. Importantly, the fact that GD3G7 significantly inhibited colony formation of HCC38(NEDD9) cells suggest that CS-E subunit plays a key role in this process. Furthermore, treatment of HCC38(NEDD9) cells with chondroitinase ABC or GD3G7 significantly inhibited mammosphere formation. Exogenous addition of CS-E enhanced colony formation and mammosphere formation of HCC38 parental and HCC38(Vector) cells. These results suggest that NEDD9 regulates the synthesis and expression of tumor associated glycocalyx structures including CS-E, which plays a key role in promoting and regulating breast cancer progression metastasis and possibly stem cell phenotypes.

The opinion and assertions contained herein are the private views of the authors and are not to be construed as official or as representing the views of the Department of the Army or the Department of Defense.

Citation Format: Iida J, Dorchak J, Clancy R, Slavik J, Cutler ML, Shriver CD. Tumor-associated glycans as key molecules to promote growth of triple-negative breast cancer cells. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-05-16.

A rectal bleeding algorithm can successfully reduce emergency admissions

AIM

Acute lower gastrointestinal bleeding (LGIB) is a common cause of emergency admissions yet rarely requires blood transfusion or radiological/surgical intervention. We aimed to develop a risk assessment tool to identify patients with acute LGIB who can be safely managed in primary care.

METHOD

We retrospectively applied an existing nomogram to 20 admissions to obtain criteria that could predict the need for transfusion. We simplified the algorithm to three criteria and developed an associated care pathway. If haemoglobin was > 13 g/dl, systolic blood pressure > 115 mmHg and the patient was not anticoagulated, admission could be avoided. These criteria were then applied to 57 prospective patients attending during a 16-week period. This was implemented with education of primary and secondary care staff, access to an emergency clinic and provision of patient information.

RESULTS

We applied our algorithm and care pathway to 57 patients with uncomplicated rectal bleeding. Thirty-five per cent (20/57) of potential admissions were avoided. Instead, patients received written information and underwent flexible sigmoidoscopy as outpatients within 6 weeks. One discharged patient was readmitted from endoscopy with severe colitis. There were no other readmissions or complications. Of the 36 patients for whom the algorithm predicted admission was needed, 33% (12/36) were anticoagulated, 94% (34/36) had haemoglobin < 13 g/dl and 42% (15/36) had a systolic blood pressure < 115 mmHg. Only one admission (1.8%) did not fulfil the admission criteria and could have potentially been avoided. Avoidable admissions reduced from 50 to 1.8%.

CONCLUSION

The application of a simple rectal bleeding algorithm can safely prevent unnecessary admissions.

Single incision laparoscopic adjustable gastric band: technique, feasibility, safety and learning curve

INTRODUCTION

Single incision laparoscopic surgery (SILS) is established in many procedures but not in bariatric surgery. One explanation may be that SILS is technically demanding in morbidly obese patients. This report describes our technique and experience with single incision laparoscopic adjustable gastric banding (SILAGB).

METHODS

Prospective data collection was performed on consecutive obese patients who underwent SILAGB between November 2009 and February 2011. A single 3 cm transverse incision in the right upper quadrant was used for a Covidien SILS™ multichannel access port. The technique is described with a standard pars flaccida approach and the 'tips and tricks' needed for a wide range of candidates using standard laparoscopic equipment.

RESULTS

A total of 29 patients (27 female) with a median body mass index of 41 kg/m(2) (range: 35-52 kg/m(2)) and median age of 44 years (range: 22-57 years) underwent SILAGB. There were no 'conversions' to a standard laparoscopic technique. Two cases required the addition of one single 5 mm port. The only complications were two postoperative wound infections (one with a port site infection requiring replacement of the port) and one faulty band requiring replacement. There were therefore two returns to theatre and no 30-day deaths. All patients were discharged on the first postoperative day. In this series, operative times reduced significantly to be comparable with the conventional laparoscopic approach.

CONCLUSIONS

SILAGB is safe and feasible in the morbidly obese. Proficiency in this technique using conventional laparoscopic equipment can be achieved with a short learning curve.

Providing nicotine dependence treatment to psychiatric inpatients: the views of Australian nurse managers

The prevalence of smoking in psychiatric settings remains high. This study aims to describe the views of nurse managers in psychiatric inpatient settings regarding the provision of nicotine dependence treatment, and whether there were associations between such views and the provision of nicotine dependence treatment. A cross-sectional survey was mailed to all public psychiatric inpatient units in New South Wales, Australia, for completion by nurse managers. Of the identified 131 service units, 123 completed questionnaires were returned (94%). Patient-related factors were considered to have a high level of influence on the provision of nicotine dependence treatment: patients requesting assistance to quit (58%), patients being receptive to interventions (52%), and patient health improving with quitting (45%). Units where the respondent reported that nicotine dependence treatment was as important as other roles were more likely to provide nicotine dependence treatment compared to units whose respondents did not hold this view (OR = 0.257, d.f. = 1, P < 0.01). While the results indicate strong support for the provision of nicotine dependence treatment, this support appears qualified by perceived patient readiness to quit, suggesting care is provided selectively rather than systematically. Positioning smoking as an addiction requiring treatment within a traditional curative approach may lead to a health service more conducive to the routine provision of nicotine dependence treatment.

Molecular evidence for Mycobacterium avium subspecies paratuberculosis (MAP) in Crohn's disease correlates with enhanced TNF-alpha secretion

BACKGROUND

Support for a role of Mycobacterium avium subspecies paratuberculosis in Crohn's disease is largely based on epidemiological evidence, as no data on mechanisms linking the presence of M. avium subspecies paratuberculosis with gut damage is available.

AIMS

To determine whether the presence of M. avium subspecies paratuberculosis contributes to the pathogenesis of Crohn's disease by promoting cytokine secretion within gut mucosa.

PATIENTS AND METHODS

A total of 235 subjects were recruited: 63 with Crohn's disease, 53 with ulcerative colitis, 45 with irritable bowel syndrome and 74 normal controls. M. avium subspecies paratuberculosis status was defined by nested PCR using IS900 sequence. Gut mucosal organ cultures were established to detect cytokine secretion patterns.

RESULTS

Significantly higher tumour necrosis factor-alpha concentrations were found in culture supernatants for Crohn's disease compared to ulcerative colitis (p<0.05), irritable bowel syndrome (p<0.01) and controls (p<0.0001). When tumour necrosis factor-alpha levels were correlated with the presence of M. avium subspecies paratuberculosis, significantly greater concentrations were only found in M. avium subspecies paratuberculosis-positive Crohn's disease patients (p<0.05). Tumour necrosis factor-alpha levels in M. avium subspecies paratuberculosis-positive Crohn's disease were significantly higher than in M. avium subspecies paratuberculosis-positive ulcerative colitis (p<0.01), M. avium subspecies paratuberculosis-positive irritable bowel syndrome (p<0.05) and M. avium subspecies paratuberculosis-positive controls (p<0.01) and all M. avium subspecies paratuberculosis-negative specimens.

CONCLUSIONS

The data link M. avium subspecies paratuberculosis with a pathogenic mechanism in Crohn's disease and is consistent with abnormal macrophage handling of M. avium subspecies paratuberculosis.

Chronic Chlamydia pneumoniae infection may promote coronary artery disease in humans through enhancing secretion of interleukin-4

Atherosclerosis is an inflammatory response, probably to a range of initiating causes. Chronic infection with Chlamydia pneumoniae (C.pn) has been suggested as one cause, but the nature of the association is controversial, in large part due to lack of an identified mechanism to link infection with the atherosclerotic process in man. This study examined 139 consecutive subjects with stable chest pain, with the aim of correlating the serological status of C.pn infection with the pattern of secretion of cytokines from CD4(+) T lymphocytes. C.pn seropositive subjects secreted significantly more interleukin (IL)-4 than did those who were C.pn seronegative (P = 0.02). No significant difference was noted for secreted interferon (IFN)-gamma. The amount of secreted IL-4, but not of secreted IFN-gamma, correlated positively with the extent of coronary artery disease (P = 0.006). A similar correlation with secreted IL-4 was not identified with Helicobacter pylori infection. These results support the hypothesis that C.pn infection contributes to the inflammatory process responsible for coronary artery atherosclerosis. The method used to detect cytokine secretion involves ligation of CD40L on blood CD4(+) T cells, which may have relevance to tissue events.

Efficacy and safety of rifabutin-containing 'rescue therapy' for resistant Helicobacter pylori infection

BACKGROUND

Current 'rescue' therapies provide inadequate Helicobacter pylori eradication rates because of antibiotic resistance.

AIM

To test the efficacy of a modified triple regimen combining rifabutin, pantoprazole and amoxicillin as rescue therapy for patients in whom eradication of H. pylori had failed standard clarithromycin-based triple therapy.

METHODS

One hundred and thirty patients (mean age 51.7 +/- 14.8 years) who had failed one or more eradication attempts with omeprazole, clarithromycin and amoxicillin were treated for 12 days with rifabutin 150 mg daily, amoxicillin 1 g or 1.5 g t.d.s, and pantoprazole 80 mg t.d.s.

RESULTS

The intention-to-treat and per-protocol eradication rates were 90.8/90.8%. Metronidazole or/and clarithromycin resistance had no significant impact on H. pylori eradication rates. A higher overall eradication rate of 96.6% (95% CI: 92.1-101%) was obtained in patients treated with a regimen containing 1.5 g amoxicillin t.d.s compared with 90.7% (95% CI: 82-98.6%) using a regimen with 1 g amoxicillin t.d.s but the difference was not significant. Side-effects reported in 40% of patients were mild.

CONCLUSION

A 12-day course of low dose of rifabutin with an increased dose of amoxicillin and pantoprazole is well-tolerated and highly effective against dual-resistant H. pylori infection after failure of triple therapy.

Enhanced clearance of Candida albicans from the oral cavities of mice following oral administration of Lactobacillus acidophilus

Orally administered live Lactobacillus acidophilus was assessed for its capacity to enhance clearance from the oral cavity of DBA/2 mice shown previously to be 'infection prone'. L. acidophilus fed to DBA/2 mice significantly shortened the duration of colonization of the oral cavity compared to controls. Enhanced clearance of Candida albicans correlated with both early mRNA gene expression for interleukin (IL)-4 and interferon (IFN)-gamma and expression of their secreted products in cultures of cervical lymph nodes stimulated with Candida antigen. In addition rapid clearance correlated with higher levels of IFN-gamma and nitric oxide in saliva. Delayed clearance, less pronounced levels of the cytokine response, saliva IFN-gamma and nitric oxide, and later mRNA expression for IL-4 and IFN-gamma relative to feeding with the L. acidophilus isolate were noted in mice fed a different Lactobacillus isolate (L. fermentum). These observations indicate significant variations in individual isolates to activate the common mucosal system.

Evaluation of anti-Helicobacter pylori IgG2 antibody for the diagnosis of Helicobacter pylori infection in western and Chinese populations

BACKGROUND

The performance of commercial Helicobacter pylori diagnostic kits developed for particular geographic regions has often been found to be of poor diagnostic value when applied to other regions, possibly because of infections being caused by different H. pylori strains in different regions.

AIM

To evaluate the performance of an IgG2 anti-H. pylori enzyme-linked immunoassay test (Helirad Alert) for detection of H. pylori infection in both Australian and Hong Kong (Chinese) subjects.

METHODS

Serum samples were tested for H. pylori specific IgG2 and IgG antibodies by enzyme-linked immunoassay kits using identical antigen preparation in 168 Australian and 160 Hong Kong (Chinese) subjects diagnosed with dyspepsia.

RESULTS

Using a cut-off value determined by analysis of H. pylori-negative Australian samples, the sensitivity, specificity and accuracy of the IgG2 assay were 77.8, 97.4 and 91.1%, respectively, for the Australian samples and 96.3, 83.8 and 90% for Hong Kong samples. For the IgG assay, sensitivity, specificity and accuracy were 87.0, 99.1 and 95.2% for Australian samples and 97.5, 75 and 86.3% for Hong Kong samples respectively. Receiver-operating characteristic analysis showed better discrimination of H. pylori status when the IgG2 assay was applied to Hong Kong samples, while the IgG assay was better in the Australian samples.

CONCLUSION

These data demonstrate that the Helirad Alert enzyme-linked immunoassay could provide a reliable method for screening H. pylori infection in both western and Chinese populations.

Nitric oxide and inflammatory mediators in the perpetuation of osteoarthritis

Articular chondrocyte production of nitric oxide (NO) and other inflammatory mediators, such as eicosanoids and cytokines, are increased in human osteoarthritis. The excessive production of nitric oxide inhibits matrix synthesis and promotes its degradation. Furthermore, by reacting with oxidants such as superoxide anion, nitric oxide promotes cellular injury and renders the chondrocyte susceptible to cytokine-induced apoptosis. PGE(2) exerts anabolic and catabolic effects on chondrocytes, depending on the microenvironment and physiologic condition. The increased expression of inducible NOS (iNOS) and cyclo-oxygenase-2 (COX-2) in OA chondrocytes is largely due to the increased expression of pro-inflammatory cytokines, particularly IL-1, which act in an autocrine/paracrine fashion to perpetuate a catabolic state that leads to progressive destruction of articular cartilage. The initiating factors for the production of inflammatory mediators include altered biomechanical forces; their continued production may be augmented by an increase in extracellular matrix proteins acting through ligation of surface integrins.

Interleukin 2 modulates ion secretion and cell proliferation in cultured human small intestinal enterocytes

AIMS

To determine if interleukin 2 (IL-2) alters epithelial transport and barrier function in cultured human small intestinal enterocytes.

METHODS

Confluent monolayers of small intestinal cells derived from duodenal biopsies were treated with IL-2 0.2-50 U/ml for 24 hours prior to study. Transport measurements were performed under short circuited conditions in Ussing chambers, with and without the secretagogues forskolin and 3-isobutyl-1-methyl xanthine (IBMX). Serosal to mucosal flux of 3[H] mannitol (permeability) and 3[H] thymidine uptake (proliferation) were measured. IL-2 receptor and cystic fibrosis transmembrane conductance regulator (CFTR) mRNA were identified using reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

IL-2 did not alter baseline electrical parameters but caused a significant increase in cAMP dependent chloride secretion. The effect was mediated by the IL-2 receptor and paralleled a rapid increase in tyrosine phosphorylation, janus kinase 1, and signal transducers and activators of transcription (STATs) 1, 3, and 5. IL-2 significantly increased proliferation but at a lower dose than observed for enhanced secretion but did not alter permeability. IL-2 receptor beta and gammac chains and CFTR mRNA were identified by RT-PCR.

CONCLUSIONS

IL-2 treatment enhances cAMP stimulated chloride secretion and cellular proliferation in a human small intestinal cell line expressing a functional IL-2 receptor.

Circulating activated endothelial cells in systemic lupus erythematosus: further evidence for diffuse vasculopathy

OBJECTIVE

In flares of systemic lupus erythematosus (SLE), endothelial cells (EC; activated by immune stimuli) are potential participants in the inflammatory processes that contribute to tissue damage. Accordingly, elevated levels of circulating endothelial cells (CEC) may be a marker for vascular injury. This study was undertaken to examine the possibility that stimulated EC are found in the circulation in patients with active SLE.

METHODS

The study cohort included 38 patients with SLE and 16 healthy controls. Immunostaining was performed on mononuclear isolates, using mouse P1H12 (endothelial-specific antibody) and rabbit antinitrotyrosine (a "footprint" of a reactive form of nitric oxide [peroxynitritel).

RESULTS

Levels of CEC were significantly higher in patients with active SLE compared with those in healthy controls (mean +/- SEM 32+/-7/ml versus 5+/-2/ml; P = 0.0028) and were correlated positively with plasma C3a in these patients (r = 0.81, P = 0.0008). Furthermore, CEC from these patients expressed an activated phenotype, as indicated by staining for nitrotyrosine.

CONCLUSION

Elevated levels of CEC observed in patients with active SLE may represent a marker of endothelial injury. The activated phenotype of these cells suggests that they may be capable of further potentiating vascular injury by the production of inflammatory and prothrombotic mediators and engaging in heterotypic aggregation with neutrophils or platelets.

Preparation and properties of S-nitroso-L-cysteine ethyl ester, an intracellular nitrosating agent

In this report, a protocol for the preparation of the hydrochloride of S-nitroso-L-cysteine ethyl ester (SNCEE.HCl; 2) is presented. The synthesis of 2 has been targeted because S-nitroso-L-cysteine (SNC; 2b), which is extensively used for trans-S-nitrosation of thiol-containing proteins, has a limited ability of crossing cellular membranes. The nitrosothiol 2 was prepared via direct S-nitrosation of the hydrochloride of L-cysteine ethyl ester (CEE.HCl; 1a) with ethyl nitrite. 2 is relatively stable in crystal form and when neutralized to SNCEE (2a) in aqueous solutions treated with chelators of metal ions. Traces of metal ions, however, triggered the decomposition of 2a to nitric oxide and a S-centered radical, which were detected by ESR spectrometry. In contrast to 2b, 2a is a lipophilic compound that was taken up by human neutrophils. The latter process was paralleled by inhibition of the NADPH oxidase-dependent generation of superoxide anion radicals, presumably via reaction(s) of intracellular trans-S-nitrosation. Intracellular accumulation of S-nitrosothiols was observed with 2a but not with 2b. It is expected that the use of 2a will be advantageous when intracellular reactions of trans-S-nitrosation are to be studied.

Activation of stress-activated protein kinase in osteoarthritic cartilage: evidence for nitric oxide dependence

OBJECTIVE

We have demonstrated in bovine chondrocytes that nitric oxide (NO) mediates IL1 dependent apoptosis under conditions of oxidant stress. This process is accompanied by activation of c-Jun NH2-terminal kinase (JNK; also called stress-activated protein kinase). In these studies we examined activation of JNK in explant cultures of human osteoarthritic cartilage obtained at joint replacement surgery and we characterized the role of peroxynitrite to act as an upstream trigger.

DESIGN

A novel technique to isolate chondrocyte proteins (<10% of total cartilage protein) from cartilage specimens was developed. It was used to analyse JNK activation by a western blot technique. To examine the hypothesis that chondrocyte JNK activation is a result of increased peroxynitrite, in vitro experiments were performed in which cultured chondrocytes were incubated with this oxidant.

RESULTS

Activated JNK was detected in the cytoplasm of osteoarthritis (OA) affected chondrocytes but not in that of controls. In vitro, chondrocytes produce NO and superoxide anion. IL-1 (48 h), which induces nitric oxide synthase, resulted in an activation of JNK; this effect was reversed by N-monomethylarginine (NMA). TNFalpha treated chondrocytes at 48 h produce superoxide anion (EPR method). Exposure of cells to peroxynitrite led to an accumulation of intracellular oxidants, in association with JNK activation and cell death by apoptosis.

CONCLUSION

We suggest that JNK activation is among the IL-1 elicited responses that injure articular chondrocytes and this activation of JNK is dependent on intracellular oxidant formation (including NO peroxynitrite). In addition, the extraction technique here described is a novel method that permits the quantitation and study of proteins such as JNK involved in the signaling pathways of chondrocytes within osteoarthritic cartilage.

A therapeutic vaccine for mucosal candidiasis

Persistent and recurrent infection of mucosal surfaces with Candida albicans is common, ranging from a nuisance to a life threatening clinical problem. No effective prophylactic or therapeutic vaccine has been developed. We have studied a mouse model of oral candida infection to identify regulatory and effector molecules of T cell activation as parameters of induced immunity, and here describe the use of this model to determine an optimal immunisation strategy. Oral immunisation with the blastospore yeast form (but not subcutaneous immunisation) induced clinical immunity, with a shift in parameters of cytokine response characterised by an early and sustained production of both IFN-gamma and IL-4 from antigen-stimulated cervical node T lymphocytes.

Quantitative apparent diffusion coefficient measurements in term neonates for early detection of hypoxic-ischemic brain injury: initial experience

PURPOSE

To determine the utility of using quantitative apparent diffusion coefficient (ADC) values as an objective means of early detection of brain injury caused by hypoxic-ischemic encephalopathy (HIE) in term neonates.

MATERIALS AND METHODS

Conventional images, diffusion-weighted images, ADC maps, and clinical charts from 13 term neonates clinically suspected of having HIE were retrospectively reviewed. Four term neonates without HIE served as control subjects. ADC values were calculated in predefined regions in patients and compared with those in control subjects. A Student t test was performed for each region to compare patients and control subjects.

RESULTS

Abnormalities were more easily detected on diffusion-weighted images and ADC maps, compared with conventional images. ADC values in patients with HIE were significantly different from those of control subjects in the posterior limb of the internal capsule, corona radiata, posterior frontal white matter, and parietal white matter bilaterally.

CONCLUSION

Evaluation of ADC maps can improve conspicuity of hypoxic-ischemic injury in the acute and/or subacute setting (within 12 days of insult), and calculation of ADC values can provide an objective measure of hypoxic-ischemic injury.

Shift of the gastric T-cell response in gastric carcinoma

BACKGROUND AND AIMS

The etiology and pathophysiology of stomach carcinoma is complex, and the mechanism whereby H. pylori directly or indirectly induces carcinoma remains unclear. In this study, interleukin (IL)-8, IL-4 and interferon (IFN)-gamma were measured in the tissue culture supernatant of gastric organ cultures from subjects with chronic gastritis with or without H. pylori infection, and with or without gastric cancer and gastric dysplasia.

RESULTS

Interleukin-8 levels were higher in cancer- and H. pylori-infected gastritis subjects than in H. pylori-negative subjects (12.95 +/- 3.16, 10.48 +/- 1.55 and 4.49 +/- 1.28 ng/mL, respectively). Elevated levels of IFN-gamma were detected in both H. pylori-infected and non-infected subjects with uncomplicated gastritis (72.23 +/- 19.0 and 34.61 +/- 5.30 pg/mL) and in non-infected dysplasia subjects (88 +/- 20.5 pg/mL). Background levels of IL-4 (< or = 9.4 pg/mL) in uncomplicated gastritis subjects and relatively high levels of IL-4 in dysplasia subjects (25.8 +/- 7.3 pg/mL) were detected. In contrast, trace amounts of IFN-gamma (16.01 +/- 0.35 pg/mL) and high levels of IL-4 (42.81 +/- 8.49 pg/mL) in gastric biopsy culture supernatants were found in cancer subjects. Mucosal IL-4 levels (but not IL-8 levels) correlated with infection and mucosal anti-H. pylori immunoglobulin G antibody.

CONCLUSIONS

The significant differences between gastritis with and without cancer and dysplasia indicated a shift from a Th1 to a Th2 helper cell pattern of cytokine secretion. This study has identified a local mucosal defect in gastric cancer. The near absence of IFN-gamma production from the mucosa at the margins of the tumor may be a critical factor in promoting growth of neoplastic cells.

Non-urease producing Helicobacter pylori in chronic gastritis

BACKGROUND

Helicobacter pylori infection is the commonest cause of gastritis. Different patterns of immune response to H. pylori infection and characteristics of bacteria are considered to contribute to clinical outcomes.

AIM

To determine characteristics of the host H. pylori relationship in subjects with non-ulcer dyspepsia and a histological diagnosis of gastritis.

METHODS

Thirty-five subjects with chronic gastritis undergoing endoscopy (mean age 53 years, range 24-82, 14 male and 21 female) were studied, none of whom was on nonsteroidal anti-inflammatory drugs or antibiotics. H. pylori infection was determined by rapid urease test (CLOtest), culture, antibody and RT-PCR for Ure C, Cag A and 26 kDa gene and histology. Cytokine production of mucosal IL-6 and IL-8 were measured by ELISA.

RESULTS

Fifteen subjects were positive by CLOtest and/or bacterial culture. In these subjects histology showed numerous helical forms of H. pylori (Group I). Nine subjects were negative by CLOtest, bacterial culture, and mRNA for urease C fragment, but positive by PCR for the 26 kDa protein encoding gene. Histology in these subjects showed the presence of either coccoid forms (four), or scant helical forms (two), or mixed coccoid/helical forms (three) (Group II). Eleven subjects were negative by all methods of detection (Group III). IgG and IgA antibody levels in serum (p<0.05) and gastric tissue culture supernatant (p<0.001) were significantly higher in Group I than those in Group II or III. There were significant differences in the IgG serum and IgA supernatant antibody levels (p<0.01 and p<0.05) when Group II was compared to Group III. Supernatant IL-6 levels were significantly higher in Group I (p<0.01) than those from Groups II and III. IL-8 levels were higher in Group I (p<0.01) and Group II (p<0.05) when compared to Group III.

CONCLUSIONS

'H. pylori-negative' gastritis can be associated with a non-urease producing form of H. pylori, with a reduction in both local and systemic antibody levels and mucosal pro-inflammatory cytokines.

Cellular and cytokine correlates of mucosal protection in murine model of oral candidiasis

Host protection against Candida albicans infection in a model of oral candidiasis involving infection-prone [DBA/2 (H-2(d))] and less infection-prone [BALB/c (H-2(d))] mouse strains was analyzed in terms of antibody and cellular responses, and in terms of cytokine patterns from regional lymph node cells. There was a selective expansion of gamma/delta(+) T-cell receptor cells, which correlated with the patterns of colonization in both mouse strains, with higher numbers of gamma/delta T cells detected in BALB/c mice. Antigen-induced T-cell proliferation was significantly higher in BALB/c mice than in DBA/2 mice. Higher levels of serum immunoglobulin G (IgG) and salivary IgA antibodies were detected in BALB/c mice than in DBA/2 mice, but only after the infection was cleared. The cervical lymph node cells from infected mice were assessed for interleukin-4 (IL-4), IL-12, and gamma interferon (IFN-gamma) mRNA gene expression by reverse transcription-PCR and protein production in the culture supernatants following restimulation in vitro. In BALB/c mice, an early increase in levels of IL-4, IFN-gamma, and IL-12 correlated with rapid elimination of C. albicans. In DBA/2 mice, where resolution of infection was delayed, IL-4 message expression was delayed and the IL-4 secretion level was lower. Neutralization of IL-4 by multiple injections of an anti-IL-4 monoclonal antibody in BALB/c mice resulted in increased carriage rate and delayed clearance of the yeasts. Collectively, the data suggest that the T-cell response to C. albicans in the regional lymph nodes which correlates best with rapid oral clearance of C. albicans is a balanced Th0 cytokine response involving early secretion of both IFN-gamma and IL-4.

Why the high rate of dropout from individualized cognitive-behavior therapy for bulimia nervosa?

OBJECT

To investigate predictors of dropout from cognitive-behavior therapy for bulimia nervosa.

METHOD

Pretreatment assessment measures were examined including the Eating Disorder Inventory-2, Body Satisfaction Questionnaire, Beck Depression Inventory, Beck Hopelessness Scale, the Locus of Control of Behavior Scale, and demographic and behavioral measures.

RESULTS

Forty-three percent (n = 14) of clients with a DSM-IV diagnosis of bulimia nervosa dropped out of treatment prematurely. No differences were found between treatment completers and dropouts with respect to the initial severity of bulimia-related symptoms. Noncompleters were, however, found to have significantly higher depression and hopelessness scores as well as elevated levels of external locus of control. Discriminate analysis showed that these variables resulted in a 90% prediction accuracy of individuals who prematurely dropped out of treatment.

DISCUSSION

Results suggest a need to focus treatment directly on factors such as hopelessness and depression in addition to standard bulimia procedures to ensure clients are able to engage in therapy.

Circulating T-cell response to Helicobacter pylori infection in chronic gastritis

BACKGROUND

Helicobacter pylori elicits a specific humoral and cellular immune response. There is increasing evidence that the type of T-cell response contributes to clinical outcome in H. pylori infection.

MATERIALS AND METHODS

The host response to H. pylori infection in 34 subjects with chronic gastritis was examined in terms of T-cell proliferation and cytokine production in whole-blood cultures stimulated or unstimulated with H. pylori acid-glycine extract antigens (AGE).

RESULTS

The proliferative response in whole-blood cultures was similar for both H. pylori-positive and -negative subjects stimulated with H. pylori AGE. While an increase in interferon-gamma (IFN-gamma) production was observed from both H. pylori-positive and -negative subjects with gastritis, significantly higher levels of IFN-gamma were detected in the former when stimulated with H. pylori AGE. In contrast, interleukin 4 (IL-4) was undetectable regardless of antigen stimulation. However, if an in situ IL-4 antibody capture assay was used, antigen-independent production of IL-4 was detected, but there was no difference between H. pylori-positive and -negative subjects with gastritis. After eradication of H. pylori, antigen-induced production of IL-4 was increased, with no decrease in the levels of secretion of IFN-gamma. IL-4 production was dependent on CD4+ T cells, as addition of anti-CD4 but not anti-CD8 mouse monoclonal antibody or matched IgG isotype to the whole-blood culture inhibited the production of IL-4.

CONCLUSION

The results suggest that a shift toward a balanced Th1-Th2 response due to an increase in antigen-induced IL-4 production from CD4+ T cells follows eradication. We suggest that the downregulation of mucosal inflammation consequent on reduction in antigen levels or removal of downregulation after eradication of H. pylori contributes to this shift in cytokine balance.

Nitric oxide synthase/COX cross-talk: nitric oxide activates COX-1 but inhibits COX-2-derived prostaglandin production

It is recognized that there is molecular cross-talk between the inflammatory mediators NO and PGs that may regulate tissue homeostasis and contribute to pathophysiological processes. However, the literature is divided with respect to whether NO activates or inhibits PG production. In this study, we sought to determine whether conflicting observations could be accounted for by divergent effects of NO on the two cyclooxygenase (COX) isoforms. Exposure of resting macrophages to NO (30 microM) enhanced PGE2 release by 4. 5-fold. This enhancement was inhibited by indomethacin but not by the COX-2 selective inhibitor NS398. To separate the activation of phospholipase A2 and COX, we performed experiments using fibroblasts derived from COX-1-deficient or COX-2-deficient mice. These cells exhibit increased basal PG production, which is due to a constitutively stimulated cytosolic phospholipase A2 and enhanced basal expression of the remaining COX isozyme. The exposure of COX- 2-deficient cells to exogenous NO (10 microM) resulted in a 2.4-fold increase of PGE2 release above controls. Further studies indicated that NO stimulated PGE2 release in COX-2-deficient cells, without altering COX-1 mRNA or protein expression. In contrast, NO inhibited COX-2-derived PGE2 production in both LPS-stimulated macrophages and COX-1 knockout cells. This inhibition was associated with both decreased expression and nitration of COX-2. Thus, these studies demonstrate divergent effects of NO on the COX isoforms. The regulation of PGE production by NO is therefore complex and will depend on the local environment in which these pleiotropic mediators are produced.