Vaccination after developing long COVID: Impact on clinical presentation, viral persistence, and immune responses.

BACKGROUND: Vaccination protects against severe COVID-19 manifestations. For those with post-COVID-19 conditions (PCC) or long COVID, the impact of COVID-19 vaccination on the evolution of symptoms, immune responses, and viral persistence is unclear. METHODS: In this prospective observational cohort study, we evaluated the number of PCC symptoms, affected organ systems, and psychological well-being scores before and after patients with PCC received COVID-19 vaccination. We simultaneously evaluated biomarkers of systemic inflammation and levels of plasma cytokines/chemokines. We measured plasma and intracellular levels of SARS-CoV-2 antigens, and immunoreactivity to SARS-CoV-2 antigens in blood. RESULTS: COVID-19 vaccination was associated with decreases in number of PCC symptoms (pre-vaccination: 6.56 ± 3.1 vs post-vaccination: 3.92 ± 4.02; P <0.001) and affected organ systems (pre-vaccination: 3.19 ± 1.04 vs post-vaccination: 1.89 ± 1.12; P <0.001), and increases in World Health Organization (WHO)-5 Well-Being Index Scores (pre-vaccination: 42.67 ± 22.76 vs post-vaccination: 56.15 ± 22.83; P <0.001). Patients with PCC also had significantly decreased levels of several pro-inflammatory plasma cytokines/chemokines after COVID-19 vaccination including sCD40L, GRO-⍺, macrophage inflammatory protein (MIP)-1⍺, interleukin (IL)-12p40, G-colony stimulating factor (CSF), M-CSF, IL-1ß, and stem cell factor (SCF). PCC participants presented a certain level of immunoreactivity toward SARS-CoV-2, that was boosted with vaccination. SARS-CoV-2 S1 antigen persisted in the blood of PCC participants, mostly in non-classical monocytes, regardless of participants receiving vaccination. CONCLUSIONS: Our study shows higher pro-inflammatory responses associated with PCC symptoms and brings forward a possible role for vaccination in mitigating PCC symptoms by decreasing systemic inflammation. We also observed persistence of viral products independent of vaccination that could be involved in perpetuating inflammation through non-classical monocytes.

Clinical Implementation of NGAL Testing to Improve Diagnostic Assessment of AKI Episodes in a Canadian Center.

Background: The differential diagnosis of acute kidney injury (AKI) episodes is often challenging. Novel AKI biomarkers have shown their utility to improve prognostic prediction and diagnostic assessment in various research populations but their implementation in standard clinical practice is still rarely reported. Objective: To report the differential diagnostic ability and associated clinical utility of the neutrophil gelatinase-associated lipocalin (NGAL) testing in a real-life setting of a heterogeneous AKI population. Design: This is a retrospective cohort study combined with a clinical audit using questionnaires distributed to consultant nephrologists following NGAL results. Setting: The first 250 consecutive patients with a confirmed AKI where an NGAL test (plasma NGAL [pNGAL] or urine NGAL [uNGAL]) was ordered from a large academic center in Montreal, Canada from January 2021 to August 2021. Patients: Patients were classified into 3 groups based on the final AKI etiology category (functional, intrarenal, and postrenal) following definitive adjudication by 2 independent nephrologists. Methods: The ability of plasma NGAL (pNGAL), urine NGAL (uNGAL), and uNGAL-to-creatinine ratio (uNGAL/Cr) to discriminate intrarenal from functional AKI etiologies was compared to standard urine chemistry (FENa) and proteinuria. A logistic regression was used to evaluate the association between intrarenal AKI and increased biomarker levels. The overall clinical utility and appreciation of the NGAL test was evaluated using a questionnaire completed prospectively by the consultant nephrologist at the time of receiving the NGAL result. The NGAL results were prospectively available to clinicians with a median time of 2.9 (1.3-7.4) hours from the initial order. Results: A total of 214 uNGAL and 44 pNGAL were ordered from 100 functional, 139 intrarenal and 11 postrenal AKI episodes after final adjudication. The discriminative ability of FENa (AUC 0.68 [95% CI: 0.61-0.75]) was lower than uNGAL (AUC 0.80 [95% CI: 0.73-0.86]) and uNGAL/Cr (AUC 0.83 [95% CI: 0.77-0.88]) but better than pNGAL (AUC 0.66 [95% CI: 0.48-0.85]). According to consultant nephrologists, the NGAL testing has led to a change in clinical management in 42% of cases. Limitations: Data reported came from a single center and NGAL was reserved for more complex cases, which limits generalizability. No biopsy has been performed for most AKI cases as the final adjudication was based on a retrospective review of the hospitalization episode. Conclusions: Neutrophil gelatinase-associated lipocalin testing can be successfully integrated as part of the diagnostic workup for AKI in clinical practice. The integration of tubular damage biomarkers to functional biomarkers can further improve the differential diagnostic assessment. However, the impact of such biomarkers on AKI management and associated outcomes still needs further validation.

Contexte: Le diagnostic différentiel des épisodes d'insuffisance rénale aiguë (IRA) pose souvent un problème. De nouveaux biomarqueurs d'IRA ont montré leur utilité pour améliorer la prédiction pronostique et l'évaluation diagnostique dans diverses populations de recherche, mais leur application dans la pratique clinique est encore peu rapportée. Objectif: Rendre compte de la capacité de diagnostic différentiel et de l'utilité clinique du test NGAL (neutrophil gelatinase-associated lipocalin) dans le contexte réel d'une population hétérogène de patients atteints d'IRA. Devis: Étude de cohorte rétrospective combinée à un audit clinique mené par l'entremise de questionnaires distribués aux néphrologues consultants à la suite du résultat NGAL. Cadre: Les 250 premiers patients consécutifs avec une IRA confirmée, pour qui un test NGAL (plasmatique [pNGAL] ou urinaire [uNGAL]) avait été demandé entre janvier et août 2021 dans un grand centre universitaire de Montréal (Canada). Sujets: Les patients ont été classés en 3 groupes selon la catégorie étiologique finale de l'IRA (fonctionnelle, intrarénale, post-rénale) après révision par deux néphrologues indépendants. Méthodologie: La capacité du pNGAL, du uNGAL et du rapport uNGAL et du rapport uNGAL sur créatinine (uNGAL/Cr) à discriminer les étiologies fonctionnelles des étiologies intrarénales a été comparée à celle des indices urinaires standard de l'urine (FENa) et de la protéinurie. Une régression logistique a servi à évaluer l'association entre l'IRA intrarénale et la hausse des taux des biomarqueurs. L'appréciation du test NGAL et son utilité clinique globale ont été évaluées à l'aide d'un questionnaire rempli prospectivement par le néphrologue consultant lors de la réception du résultat NGAL. Les résultats NGAL ont été mis à la disposition des cliniciens de manière prospective, dans un délai médian de 2,9 [1,3-7,4] heures suivant la prescription initiale. Résultats: En tout, après la révision finale, 214 tests uNGAL et 44 tests pNGAL ont été demandés à partir de 100 épisodes d'IRA fonctionnelle, 139 épisodes d'IRA intrarénale et 11 épisodes d'IRA post-rénale. La capacité discriminante du FENa (SSC: 0,68 [IC 95 %: 0,61-0,75]) était inférieure à celles du uNGAL (SSC: 0,80 [IC 95 %: 0,73-0,86]) et du rapport uNGAL/ Cr (SSC: 0,83 [IC 95 %: 0,77-0,88]), mais supérieure à celle du pNGAL (SSC: 0,66 [IC 95 %: 0,48-0,85]). Les néphrologues ont indiqué que les tests NGAL avaient entraîné un changement dans la prise en charge clinique dans 42 % des cas. Limites: Les données provenaient d'un seul centre et le test NGAL était réservé aux cas plus complexes, ce qui limite la généralisabilité. Dans la plupart des cas, aucune biopsie n'a été effectuée et le diagnostic final était basé sur un examen rétrospectif de l'hospitalisation. Conclusions: En pratique clinique, les tests NGAL peuvent être intégrés avec succès au diagnostic de l'IRA. L'intégration des biomarqueurs de lésions tubulaires aux biomarqueurs fonctionnels peut améliorer davantage l'évaluation du diagnostic différentiel. Cependant, l'impact de ces biomarqueurs sur la prise en charge de l'IRA et les résultats connexes doit encore être validé.

Voriconazole Sequestration During Extracorporeal Membrane Oxygenation for Invasive Lung Aspergillosis: A Case Report.

The increasing use of extracorporeal membrane oxygenation (ECMO) in critical care introduces new challenges with medication dosing. Voriconazole, a commonly used antifungal and the first-choice agent for the treatment of invasive aspergillosis, is a poorly water-soluble and highly protein-bound drug. Significant sequestration in ECMO circuits can be expected; however, no specific dosing recommendations are available. We report on the therapeutic drug monitoring and clinical evolution of a patient treated with voriconazole for invasive pulmonary aspergillosis while receiving ECMO therapy. Voriconazole trough levels were persistently low (<1 µg/mL) after initiation of ECMO despite additional loading doses and dose increases. Voriconazole dose had to be increased to 6.5 mg/kg three times daily to obtain therapeutic trough levels. The inability to achieve therapeutic levels of voriconazole for a prolonged period (a minimum of 9 days) while undergoing ECMO therapy is believed to have been a significant contributing factor in the patient's fatal outcome. Therapeutic trough levels of voriconazole cannot be guaranteed with standard dosing in patients undergoing ECMO and much higher doses may be necessary. Empirical use of higher doses and/or combination therapy may be reasonable and frequent therapeutic drug monitoring is mandatory.

Characterization of hyperlipidemia secondary to mitotane in adrenocortical carcinoma.

Background: This study examined the magnitude of changes and the time required to observe maximal changes in LDL-c, HDL-c, triglycerides (Tg) and non-HDL-c after the introduction of mitotane. Methods: Retrospective study of 45 patients with adrenocortical carcinoma who were treated at the Centre hospitalier de l'Université de Montréal. Clinical and biochemical data were collected, including lipid profiles before and during the first year of treatment with mitotane. Results: Among the 45 studied patients, 26 (58%) had a complete lipid profile before the introduction of mitotane and at least 1 lipid profile during the first year of treatment, and 19 patients (42%) had a lipid profile following initiation of the treatment. Among the 26 patients who had lipid profiles before and after the introduction of mitotane, the increase of LDL-c was 2.19 mmol/L (76%) (P< 0.0001), HDL-c was 0.54 mmol/L (35%) (P= 0.0002), Tg was 1.80 mmol/L (129%) (P< 0.0001) and non-HDL-c was 2.73 mmol/L (79%) (P< 0.0001). Between the first and the sixth month of mitotane treatment, peak values (n = 45) of LDL-c and non-HDL-c were reached in 42 patients (93%) and 37 patients (82%), respectively, whereas peak values of HDL-c were reached after 6 months of mitotane treatment in 29 patients (66%). The peak value of Tg was almost equal throughout the first year. The mean peak values of HDL-c, Tg and non-HDL-c showed significant associations with their respective mitotane concentrations (ß = 0.352, P= 0.03; ß = 0.406, P= 0.02 and ß = 0.339, P= 0.05). Conclusion: The introduction of mitotane produces a clinically significant elevation of lipid parameters (LDL-c, HDL-c, Tg and non-HDL-c) during the first year of treatment.

Colchicine for community-treated patients with COVID-19 (COLCORONA): a phase 3, randomised, double-blinded, adaptive, placebo-controlled, multicentre trial.

BACKGROUND: Evidence suggests a role for excessive inflammation in COVID-19 complications. Colchicine is an oral anti-inflammatory medication beneficial in gout, pericarditis, and coronary disease. We aimed to investigate the effect of colchicine on the composite of COVID-19-related death or hospital admission. METHODS: The present study is a phase 3, randomised, double-blind, adaptive, placebo-controlled, multicentre trial. The study was done in Brazil, Canada, Greece, South Africa, Spain, and the USA, and was led by the Montreal Heart Institute. Patients with COVID-19 diagnosed by PCR testing or clinical criteria who were not being treated in hospital were eligible if they were at least 40 years old and had at least one high-risk characteristic. The randomisation list was computer-generated by an unmasked biostatistician, and masked randomisation was centralised and done electronically through an automated interactive web-response system. The allocation sequence was unstratified and used a 1:1 ratio with a blocking schema and block sizes of six. Patients were randomly assigned to receive orally administered colchicine (0·5 mg twice per day for 3 days and then once per day for 27 days thereafter) or matching placebo. The primary efficacy endpoint was the composite of death or hospital admission for COVID-19. Vital status at the end of the study was available for 97·9% of patients. The analyses were done according to the intention-to-treat principle. The COLCORONA trial is registered with ClinicalTrials.gov (NCT04322682) and is now closed to new participants. FINDINGS: Trial enrolment began in March 23, 2020, and was completed in Dec 22, 2020. A total of 4488 patients (53·9% women; median age 54·0 years, IQR 47·0-61·0) were enrolled and 2235 patients were randomly assigned to colchicine and 2253 to placebo. The primary endpoint occurred in 104 (4·7%) of 2235 patients in the colchicine group and 131 (5·8%) of 2253 patients in the placebo group (odds ratio [OR] 0·79, 95·1% CI 0·61-1·03; p=0·081). Among the 4159 patients with PCR-confirmed COVID-19, the primary endpoint occurred in 96 (4·6%) of 2075 patients in the colchicine group and 126 (6·0%) of 2084 patients in the placebo group (OR 0·75, 0·57-0·99; p=0·042). Serious adverse events were reported in 108 (4·9%) of 2195 patients in the colchicine group and 139 (6·3%) of 2217 patients in the placebo group (p=0·051); pneumonia occurred in 63 (2·9%) of 2195 patients in the colchicine group and 92 (4·1%) of 2217 patients in the placebo group (p=0·021). Diarrhoea was reported in 300 (13·7%) of 2195 patients in the colchicine group and 161 (7·3%) of 2217 patients in the placebo group (p<0·0001). INTERPRETATION: In community-treated patients including those without a mandatory diagnostic test, the effect of colchicine on COVID-19-related clinical events was not statistically significant. Among patients with PCR-confirmed COVID-19, colchicine led to a lower rate of the composite of death or hospital admission than placebo. Given the absence of orally administered therapies to prevent COVID-19 complications in community-treated patients and the benefit of colchicine in patients with PCR-proven COVID-19, this safe and inexpensive anti-inflammatory agent could be considered for use in those at risk of complications. Notwithstanding these considerations, replication in other studies of PCR-positive community-treated patients is recommended. FUNDING: The Government of Quebec, the Bill & Melinda Gates Foundation, the National Heart, Lung, and Blood Institute of the US National Institutes of Health, the Montreal Heart Institute Foundation, the NYU Grossman School of Medicine, the Rudin Family Foundation, and philanthropist Sophie Desmarais.

Prevalence of Celiac Disease in Patients with Primary Biliary Cholangitis.

BACKGROUND: Primary biliary cholangitis (PBC) frequently coexists with other autoimmune diseases, including celiac disease (CeD). Although the prevalence of CeD is high among cohorts with PBC, few studies have directly compared this prevalence to those among individuals with other liver diseases (OLD). AIM: To compare the prevalence of CeD between a cohort with PBC and a cohort with OLD. METHODS: Retrospective study from January 2013 to December 2016. All consecutive patients with an anti-transglutaminase (tTG) assay requested by a hepatologist and a diagnosis of chronic liver disease were included. CeD diagnosis was confirmed by duodenal biopsies. RESULTS: We included 399 consecutive patients (53.1 years SD 14.0, 54.1% women), notably 51 individuals with PBC and 348 individuals with OLD. PBC group included significantly more women (90.2% versus 48.9% P < 0.0001). The prevalence of CeD was higher in the group with PBC compared to the group with OLD (11.8 versus 2.9%, P < 0.003). In the OLD group, the prevalence of CeD was comparable regardless of the etiologic subgroup (nonalcoholic steatohepatitis 2.7% versus alcoholic liver disease 4.3%, versus viral 1.5% versus other autoimmune liver diseases 3.3%, NS). The presence of gastrointestinal symptoms at the time of the tTG assay was comparable between PBC and OLD groups (31.4 versus 29.6%, NS). CONCLUSION: There is a higher prevalence of CeD in the PBC group compared to other liver diseases.

Improved Sample Quality and Decreased Turnaround Time When Using Plasma Blood Collection Tubes with a Mechanical Separator in a Large University Hospital.

BACKGROUND: Serum is commonly used for clinical chemistry testing but many conditions can affect the clotting process, leading to poor sample quality and impaired workflow. With serum gel tubes, we found a high proportion of sample probe aspiration errors on our Beckman AU5800 analyzers. We decided to implement the BD Barricor™ plasma tubes, and we validated an off-specification centrifugation scheme and verified that results obtained for 65 chemistry and immunochemistry tests were comparable to those obtained in serum gel tubes. Finally, we evaluated the impact of this new tube on sample error rate and laboratory turnaround time. METHODS: To validate centrifugation settings, 50 paired samples were collected in Barricor tubes and centrifuged at 1912 × g for 10 min or 5 min (off-specification). To compare serum gel tubes with Barricor plasma tubes, 119 paired samples were collected from volunteers and results were analyzed using weighed Deming regression. Finally, the proportion of aspiration errors and laboratory TAT for potassium were measured before and after implementing Barricor tubes. RESULTS: Barricor tubes showed clinically acceptable equivalence to serum gel tubes for the studied analytes, and the off-specification centrifugation scheme did not affect the results. Implementing Barricor tubes improved the laboratory workflow by decreasing the aspiration error rates (2.01% to 0.77%, P < 0.001) and lowering hemolysis (P < 0.001). The laboratory TAT for potassium were also significantly lowered (P < 0.001). CONCLUSION: Use of Barricor tubes instead of serum gel tubes leads to better sample quality, shorter more reproducible laboratory TAT, and decreases costs associated with error management.

Discordance Between Serology and Histology for Celiac Disease in a Cohort with Coexisting Liver Disorders.

BACKGROUND: The liver and celiac disease (CeD) share a complex relationship. While in some patients, isolated hypertransaminasemia is the only manifestation of CeD, liver diseases (LD) may also be associated with the presence of isolated tissue transglutaminase antibodies IgA (tTG IgA) without histologic evidence of CeD. AIMS: To examine the yield of tTG IgA testing (a) in the workup for chronic liver disease (CLD) or cytolysis and (b) to identify biopsy-confirmed CeD (BxCeD) among patients with concomitant LD. METHODS: Retrospective study including two cohorts. Cohort 1 represented 444 consecutive individuals without known CeD for which liver specialists requested tTG IgA. Incidence of positive tTG and BxCeD was evaluated. Cohort 2 included 212 consecutive individuals with positive tTG IgA and subsequent duodenal biopsies. The frequency and clinical characteristics of individuals without BxCeD were examined, with and without concurrent LD. RESULTS: The rate of first time positive tTG IgA among the tests requested by a liver specialist (cohort 1) was 2.0% (n = 9). However, 33.0% (n = 3) of these patients did not have BxCeD. Cohort 2 included 33 individuals with coexisting LD, of which 42.4% did not have BxCeD, compared with 16.2% of the patients without LD (P < 0.001). The majority of the patients without BxCeD (65.1%) showed an increase < 3 times upper limit of normal of tTG IgA. CONCLUSIONS: Although there is clinical value in testing for CeD in the context of LD, there could be a high rate of positive CeD serology unaccompanied by histologic signs in patients with coexisting LD.

Efficacy of an intrathecal multidrug infusion for pain control in older adults and in end-stage malignancies: A report of three cases.

The aim of the present study was to explore the effectiveness of an alternative method to manage pain based on a time-limited intrathecal (IT) infusion of an analgesic medication mixture. Three patients (69, 64 and 94 years of age) with intractable and poorly controlled pain due to bed sores, pelvic metastatic mass, and thoracic vertebra and rib fractures, respectively, were treated. Daily doses of opioids could not be increased due to side effects. An IT catheter (20 G) was placed by percutaneous approach in the lumbar area while advancing toward the thoracic region, and was then tunnelled and fixed subcutaneously. It was connected to an external infusion pump with a mixture of bupivacaine 1 mg/mL, naloxone 0.02 ng/mL, ketamine 100 µg/mL, morphine 0.01 mg/mL and clonidine 0.75 µg/mL. The starting rate was 1 mL/h. The pain was mostly controlled at a rate of <1 mL/h. Opioid consumption was reduced dramatically. The catheter was kept in place for one month in the first and third patients, and for six months in the second patient, until his death. Major side effects, such as hypotension, constipation, muscle weakness, sphincter dysfunction, and cognitive or mood deterioration, were not observed with this approach. One patient experienced a urinary tract infection followed by sepsis and meningitis, which was cured by antibiotics. The catheter was removed in this patient. IT infusion with a low-concentration multidrug mixture could be considered as an alternative modality for intractable pain relief in older adults or in malignancies.

Midodrine in patients with spinal cord injury and anejaculation: A double-blind randomized placebo-controlled pilot study.

OBJECTIVE: The objective of this study is to evaluate the efficacy of midodrine in the treatment of anejaculation in men with spinal cord injury (SCI). STUDY DESIGN: Prospective, double-blind, randomized, placebo-controlled pilot study. METHOD: Men with anejaculation associated with SCI (level of injury above T10) of more than 1 year in duration were approached. Those with no ejaculatory response to one penile vibratory stimulation (PVS) trial were assigned in a double-blind manner to one of the two following interventions once a week for a maximum of 3 weeks or until ejaculation occurred: oral administration of flexible midodrine (7.5-22.5 mg max) followed by PVS (group M), or oral administration of flexible sham-midodrine (placebo) followed by PVS (group P). Sociodemographic data, medical characteristics, and plasma desglymidodrine concentration were collected for all participants. OUTCOME MEASURE: Ejaculation success rate in each group. RESULTS: Among the 78 men approached, 23 participants (level of SCI: C4-T9) were randomized. Three participants abandoned the study and 20 completed the study; 10 were assigned to group M, 10 to group P. Ejaculation was reached for one participant of group M and for two participants of group P. Autonomic dysreflexia associated to PVS occurred in three patients. CONCLUSION: In this small sample study, treatment of anejaculation after SCI with midodrine and PVS did not result in a better rate of antegrade ejaculation in 10 men than in 10 men treated with a placebo and PVS.

Successful and cost-efficient replacement of immunoassays by tandem mass spectrometry for the quantification of immunosuppressants in the clinical laboratory.

The purpose of this paper is to describe the implantation of mass spectrometry in replacement of immunoassays for the measurement of immunosuppressant drugs in the clinical setting, from scientific and financial perspectives. A straightforward, rapid, and economical method was developed for the simultaneous quantification of tacrolimus, sirolimus, and cyclosporine. Following a simple protein precipitation step, supernatants are injected on a small C(18) guard cartridge and gradient elution of the immunosuppressants is performed in a total chromatographic run time of 2.25 min. Sodium adducts of the compounds and internal standards are quantified by electrospray tandem mass spectrometry. The method shows inter-assay impression of less than 10-15% for all compounds with good extraction efficiency (89-104%) and minimal matrix effects, except for sirolimus where ion suppression is more pronounced. The method correlates well with chemiluminescent microparticle immunoassays (on the Abbott Architect analyzer), although the immunoassay results are significantly higher than those obtained by HPLC-MS/MS. The transition from immunoassays to mass spectrometry was well received by the laboratory staff, and significant reductions in reagent costs have been realized (>$250,000 CAD per year). With these savings, the purchase and installation of two complete HPLC-MS/MS systems was completely financed in less than three years.

Development and validation of a rapid liquid chromatography isotope dilution tandem mass spectrometry (LC-IDMS/MS) method for serum creatinine.

OBJECTIVES: To develop an isotope dilution liquid chromatography tandem mass spectrometry (LC-IDMS/MS) method for the standardization of serum creatinine. DESIGN AND METHODS: Supernatants obtained by protein precipitation were injected into a LC-MS/MS. Chromatography was performed on a cation exchanger pre-column in normal phase isocratic mode. Creatinine and creatinine-D(3) were quantified using ion transitions of m/z 114-->44 and 117-->47, respectively. RESULTS: The method was calibrated with the NIST Standard Reference Material 914a and was found to be exact in analyzing the certified reference material SRM 967 from NIST (97.1+/-0.9% and 102.1+/-0.9% of target value for levels 1 and 2, respectively) and by calculating recuperation of spiked creatinine in 10 different patient samples (103.6+/-4.1%). Intra-assay imprecision was 0.9% at both 64.6 and 354 micromol/L creatinine, while inter-assay imprecisions were 1.9% and 1.8%. Absence of ion suppression was confirmed by spiking experiments. The method was shown to be free of carryover. A good correlation was obtained between the LC-MS/MS method and a Jaffe method run on an automated analyzer (r=0.999). CONCLUSIONS: We have developed a fast and simple method for the quantification of serum creatinine by isotope dilution tandem mass spectrometry (IDMS/MS) and we propose that this method can be used as a reference method by laboratories that wish to validate their serum creatinine automated assay.

Photo-crosslinking of proteins in intact cells reveals a dimeric structure of cyclooxygenase-2 and an inhibitor-sensitive oligomeric structure of microsomal prostaglandin E2 synthase-1.

We have characterized the structures of cyclooxygenase-2 (COX-2) and microsomal prostaglandin E(2) synthase-1 (mPGES-1) in intact cells using bifunctional and photo-activatable crosslinking agents. A dimeric complex was detected for COX-2 by both crosslinking approaches, consistent with the crystal structure of the enzyme. For mPGES-1, treatment of A549 cells with disuccinimidyl suberate yielded immunoreactive protein bands corresponding to a dimer (33 kDa) and a trimer (45 kDa), as observed for the isolated enzyme. Photo-crosslinking with photoactivatable methionine in intact cells generated complexes with molecular weights corresponding to the dimer (33 kDa) and two putative trimer forms (50 and 55 kDa). Treatment with the selective mPGES-1 inhibitor MF63 prevented the formation of the 50 and 55 kDa crosslinked complexes, while an inactive structural analogue had no effect. Our data indicate that COX-2 forms a dimer in intact cells and that mPGES-1 has an oligomeric structure that can be disrupted by a selective inhibitor.

Down-regulation of microsomal prostaglandin E2 synthase-1 in adipose tissue by high-fat feeding.

OBJECTIVE: Prostaglandin (PG)E2 is a lipid mediator implicated in inflammatory diseases and in the regulation of lipolysis and adipocyte differentiation. This work was, thus, undertaken to study the regulation of the various PGE2 synthases (PGESs) in obesity. RESEARCH METHODS AND PROCEDURES: C57Bl/6 mice were subjected to a high-fat or regular diet for 12 weeks. The levels of PGE2 in white adipose tissue (WAT) of lean and obese mice were quantified by liquid chromatography-mass spectrometry, and the change in expression of the three major PGES caused by diet-induced obesity was characterized by Western blotting. Human preadipocytes and 3T3-L1 cells were used to assess the expression of microsomal prostaglandin E2 synthase-1 (mPGES-1) during adipogenesis. RESULTS: mPGES-1, mPGES-2, and cytosolic PGES proteins were all detected in WAT of lean animals. mPGES-1 was expressed at higher levels in WAT than in any other tissues examined and was more abundant (3- to 4-fold) in epididymal (visceral) compared with inguinal (subcutaneous) WAT. Expression of mPGES-1 was also detected in undifferentiated and differentiated 3T3-L1 cells and in human primary subcutaneous preadipocytes at all stages of adipogenesis. The mPGES-1 protein was substantially down-regulated in epididymal and inguinal WAT of obese mice, whereas mPGES-2 and cytosolic PGES remained relatively stable. Concordantly, the PGE2 levels in obese inguinal WAT were significantly lower than those of lean animals. DISCUSSION: These data suggest that mPGES-1 is the major form of PGESs contributing to the synthesis of PGE2 in WAT and that its down-regulation might be involved in the alterations of lipolysis and adipogenesis associated with obesity.

Double-label expression studies of prostacyclin synthase, thromboxane synthase and COX isoforms in normal aortic endothelium.

We have performed double-label immunofluorescence microscopy studies to evaluate the extent of co-localization of prostacyclin synthase (PGIS) and thromboxane synthase (TXS) with cyclooxygenase (COX)-1 and COX-2 in normal aortic endothelium. In dogs, COX-2 expression was found to be restricted to small foci of endothelial cells while COX-1, PGIS and TXS were widely distributed throughout the endothelium. Quantification of the total cross-sectioned aortic endothelium revealed a 6- to 7-fold greater expression of COX-1 relative to COX-2 (55 vs. 8%) and greater co-distribution of PGIS with COX-1 compared to COX-2 (19 vs. 3%). These results are in contrast to the extensive co-localization of PGIS and COX-2 in bronchiolar epithelium. In rat and human aortas, immunofluorescence studies also showed significant COX-1 and PGIS co-localization in the endothelium. Only minor focal COX-2 expression was detected in rat endothelium, similar to the dog, while COX-2 was not detected in human specimens. Inhibition studies in rats showed that selective COX-1 inhibition caused a marked reduction of 6-keto-PGF(1alpha) and TXB(2) aortic tissue levels, while COX-2 inhibition had no significant effect, providing further evidence for a functionally larger contribution of COX-1 to the synthesis of prostacyclin and thromboxane in aortic tissue. The data suggest a major role for COX-1 in the production of both prostacyclin and thromboxane in normal aortic tissue. The extensive co-localization of PGIS and COX-2 in the lung also indicates significant tissue differences in the co-expression patterns of these two enzymes.

Cyclo-oxygenase-2 contributes to constitutive prostanoid production in rat kidney and brain.

Cyclo-oxygenases (COXs) catalyse the synthesis of PGH2 (prostaglandin H2), which serves as the common substrate for the production of PGE2, PGD2, PGF(2alpha), prostacyclin (or PGI2) and TXs (thromboxanes). While COX-1 is the major isoform responsible for prostanoid synthesis in healthy tissues, little information is available on the contribution of constitutive COX-2 to the various prostanoid synthetic pathways under non-inflammatory conditions. To evaluate further the role of COX-2 in prostanoid biosynthesis, rats were acutely treated with the selective COX-1 inhibitor SC-560 [5-(4-chlorophenyl)-1-(4-methoxyphenyl)-3-trifluoromethylpyrazole] or the selective COX-2 inhibitors MF tricyclic [3-(3,4-difluorophenyl)-4-(4-(methylsulphonyl)phenyl)-2-(5H)-furanone] and DFU [5,5-dimethyl-3-(3-fluorophenyl)-4-(4-methylsulphonyl)phenyl-2-(5H)-furanone]. Selected tissues were then processed for a complete analysis of their prostanoid content by liquid chromatography MS. Whereas the treatment with SC-560 caused a 60-70% inhibition in the total prostanoid content of most tissues examined, a significant decrease (35-50%) in total prostanoid content following selective COX-2 inhibition was solely detected for kidney and brain tissues. Analysis of the individual prostanoids reveals significant inhibition of 6-oxo-PGF(1alpha), PGE2, PGD2, PGF(2alpha) and TXB2 in the kidney and inhibition of all these prostanoids with the exception of PGD2 in the forebrain. These results demonstrate that constitutively expressed COX-2 contributes to the production of prostanoids in kidney and brain for each of the PGE2, PGI2 and TXB2 pathways under non-inflammatory conditions. Approaches to modulate inflammation through specific inhibition of terminal synthases, such as mPGES-1 (microsomal PGE2 synthase-1), thus have the potential to differ from COX-2 inhibitors and non-selective non-steroidal anti-inflammatory drugs with regard to effects on constitutive prostanoid synthesis and on renal function.