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Invasive mold infections (IMI) directly impact life expectancy, especially with delayed therapy. Among IMI, aspergillosis (IA) is more common than mucormycosis (IM), resulting in IA-targeted empirical treatment with voriconazole for suspected invasive pulmonary aspergillosis (IPA), despite IM ineffectiveness. Recently, isavuconazole was approved in Canada for IA and IM. The primary objective was to assess the cost-effectiveness of isavuconazole compared to voriconazole for suspected IPA in Canada. A secondary objective was to assess the impact of varying time horizons to address the wide spectrum of life expectancies, according to patients underlying diseases. A 5-year decision-tree was developed from the Canadian Ministry of Health (MoH) and societal perspectives. Efficacy parameters were extracted from SECURE/VITAL trials. Costs included treatment acquisition, hospitalization, adverse events and productivity loss. 3- and 10-year time horizon alternative scenarios and extensive sensitivity analyses were also conducted. From a MoH perspective, isavuconazole compared to voriconazole resulted in an incremental cost-utility ratio (ICUR) of $C30,160/QALY. 3- and10-year ICURs were also cost-effective, relative to a willingness-to-pay threshold of $C50,000/QALY. This study demonstrates that, in comparison to voriconazole, isavuconazole is a cost-effective strategy for the treatment of patients with suspected IPA, regardless of their life expectancy. [ABSTRACT FROM AUTHOR]

Abstract Background Oxidative Stress contributes to the pathogenesis of many diseases. The NRF2/KEAP1 axis is a key transcriptional regulator of the anti-oxidant response in cells. Nrf2 knockout mice have implicated this pathway in regulating inflammatory airway diseases such as asthma and COPD. To better understand the role the NRF2 pathway has on respiratory disease we have taken a novel approach to define NRF2 dependent gene expression in a relevant lung system. Methods Normal human lung fibroblasts were transfected with siRNA specific for NRF2 or KEAP1. Gene expression changes were measured at 30 and 48 hours using a custom Affymetrix Gene array. Changes in Eotaxin-1 gene expression and protein secretion were further measured under various inflammatory conditions with siRNAs and pharmacological tools. Results An anti-correlated gene set (inversely regulated by NRF2 and KEAP1 RNAi) that reflects specific NRF2 regulated genes was identified. Gene annotations show that NRF2-mediated oxidative stress response is the most significantly regulated pathway, followed by heme metabolism, metabolism of xenobiotics by Cytochrome P450 and O-glycan biosynthesis. Unexpectedly the key eosinophil chemokine Eotaxin-1/CCL11 was found to be up-regulated when NRF2 was inhibited and down-regulated when KEAP1 was inhibited. This transcriptional regulation leads to modulation of Eotaxin-1 secretion from human lung fibroblasts under basal and inflammatory conditions, and is specific to Eotaxin-1 as NRF2 or KEAP1 knockdown had no effect on the secretion of a set of other chemokines and cytokines. Furthermore, the known NRF2 small molecule activators CDDO and Sulphoraphane can also dose dependently inhibit Eotaxin-1 release from human lung fibroblasts. Conclusions These data uncover a previously unknown role for NRF2 in regulating Eotaxin-1 expression and further the mechanistic understanding of this pathway in modulating inflammatory lung disease.

Background: Nirmatrelvir/ritonavir has shown to reduce COVID-19 hospitalization and death before Omicron, but updated real-world evidence studies are needed. This study aimed to assess whether nirmatrelvir/ritonavir reduces the risk of COVID-19-associated hospitalization among high-risk outpatients., Methods: A retrospective cohort study of outpatients with SARS-CoV-2 between March 15 and 15 October 2022, using data from the Quebec clinico-administrative databases. Outpatients treated with nirmatrelvir/ritonavir were compared with infected ones not receiving nirmatrelvir/ritonavir using propensity-score matching. Relative risk (RR) of COVID-19-associated hospitalization within 30 days was assessed using a Poisson regression., Results: A total of 8402 treated outpatients were matched to controls. Regardless of vaccination status, nirmatrelvir/ritonavir treatment was associated with a 69% reduced RR of hospitalization (RR: .31; 95% CI: .28; .36; number needed to treat [NNT] = 13). The effect was more pronounced in outpatients with incomplete primary vaccination (RR: .04; 95% CI: .03; .06; NNT = 8), while no benefit was found in those with a complete primary vaccination (RR: .93; 95% CI: .78; 1.08). Subgroups analysis among high-risk outpatients with a complete primary vaccination showed that nirmatrelvir/ritonavir treatment was associated with a significant decrease in the RR of hospitalization in severely immunocompromised outpatients (RR: .66; 95% CI: .50; .89; NNT = 16) and in high-risk outpatients aged ≥70 years (RR: .50; 95% CI: .34; .74; NNT = 10) when the last dose of the vaccine was received at least 6 months ago., Conclusions: Nirmatrelvir/ritonavir reduces the risk of COVID-19-associated hospitalization among incompletely vaccinated high-risk outpatients and among some subgroups of completely vaccinated high-risk outpatients., Competing Interests: Potential conflicts of interest. M. R. T. reports an issued or pending patent (US 11,359,010 B2) for humanized anti-S100A9 antibody and uses thereof (no royalties to date). A. F. T. is the chairholder of the Canada Research Chair in Critical Care Neurology and Trauma. M.-L. L. reports consulting fees from Takeda and Merck. H. C. reports grants or contracts from Novartis, Roche, Sanofi, and Merck for participation in COVID-19–related trials (paid to their institution) and unpaid participation on the medical board of an immunodeficient patient advocacy group (Quebec and Canada). M. Brosseau reports a grant from AstraZeneca as the local principal investigator for the Efficacy and Safety of Tozorakimab in Patients Hospitalised for Viral Lung Infection Requiring Supplemental Oxygen (TILIA) study (paid to their institution). E. H. reports an ongoing patent from Immune BioSolutions for an anti–SARS-CoV-2 monoclonal antibody, and an unpaid position as President Elect of the Clinical Immunology Society. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2023. Published by Oxford University Press on behalf of Infectious Diseases Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: High-fidelity simulations based on real-life clinical scenarios have frequently been used to improve patient care, knowledge and teamwork in the acute care setting. Still, they are seldom included in the allergy-immunology curriculum or continuous medical education. Our main goal was to assess if critical care simulations in allergy improved performance in the clinical setting., Methods: Advanced anaphylaxis scenarios were designed by a panel of emergency, intensive care unit, anesthesiology and allergy-immunology specialists and then adapted for the adult allergy clinic setting. This simulation activity included a first part in the high-fidelity simulation-training laboratory and a second at the adult allergy clinic involving actors and a high-fidelity mannequin. Participants filled out a questionnaire, and qualitative interviews were performed with staff after they had managed cases of refractory anaphylaxis., Results: Four nurses, seven allergy-immunology fellows and six allergy/immunologists underwent the simulation. Questionnaires showed a perceived improvement in aspects of crisis and anaphylaxis management. The in-situ simulation revealed gaps in the process, which were subsequently resolved. Qualitative interviews with participants revealed a more rapid and orderly response and improved confidence in their abilities and that of their colleagues to manage anaphylaxis., Conclusion: High-fidelity simulations can improve the management of anaphylaxis in the allergy clinic and team confidence. This activity was instrumental in reducing staff reluctance to perform high-risk challenges in the ambulatory setting, thus lifting a critical barrier for implementing oral immunotherapy at our adult center., (© 2023. The Author(s).)

Background: In patient requiring vasopressors, the radial artery pressure may underestimate the true central aortic pressure leading to unnecessary interventions. When using a femoral and a radial arterial line, this femoral-to-radial arterial pressure gradient (FR-APG) can be detected. Our main objective was to assess the accuracy of non-invasive blood pressure (NIBP) measures; specifically, measuring the gradient between the NIBP obtained at the brachial artery and the radial artery pressure and calculating the non-invasive brachial-to-radial arterial pressure gradient (NIBR-APG) to detect an FR-APG. The secondary objective was to assess the prevalence of the FR-APG in a targeted sample of critically ill patients., Methods: Adult patients in an intensive care unit requiring vasopressors and instrumented with a femoral and a radial artery line were selected. We recorded invasive radial and femoral arterial pressure, and brachial NIBP. Measurements were repeated each hour for 2 h. A significant FR-APG (our reference standard) was defined by either a mean arterial pressure (MAP) difference of more than 10 mmHg or a systolic arterial pressure (SAP) difference of more than 25 mmHg. The diagnostic accuracy of the NIBR-APG (our index test) to detect a significant FR-APG was estimated and the prevalence of an FR-APG was measured and correlated with the NIBR-APG., Results: Eighty-one patients aged 68 [IQR 58-75] years and an SAPS2 score of 35 (SD 7) were included from which 228 measurements were obtained. A significant FR-APG occurred in 15 patients with a prevalence of 18.5% [95%CI 10.8-28.7%]. Diabetes was significantly associated with a significant FR-APG. The use of a 11 mmHg difference in MAP between the NIBP at the brachial artery and the MAP of the radial artery led to a specificity of 92% [67; 100], a sensitivity of 100% [95%CI 83; 100] and an AUC ROC of 0.93 [95%CI 0.81-0.99] to detect a significant FR-APG. SAP and MAP FR-APG correlated with SAP (r 2  = 0.36; p < 0.001) and MAP (r 2  = 0.34; p < 0.001) NIBR-APG., Conclusion: NIBR-APG assessment can be used to detect a significant FR-APG which occur in one in every five critically ill patients requiring vasoactive agents., (© 2021. The Author(s).)

Study Objective: We evaluate the incidence of complications associated with the use of nitrates in patients presenting with acute pulmonary edema and concomitant moderate or severe aortic stenosis compared with patients without aortic stenosis. Nitrates are contraindicated in severe aortic stenosis because of the theoretical yet unproven risk of precipitating profound hypotension., Methods: A cohort design with retrospective chart review study was conducted at two Canadian hospitals. Patients with aortic stenosis (moderate or severe) and without aortic stenosis were included if they presented with acute cardiogenic pulmonary edema, received intravenous or sublingual nitroglycerin, and had an echocardiography report available. The primary outcome was clinically relevant hypotension, defined as hypotension leading to any of the following predefined events: nitroglycerin discontinuation, intravenous fluid bolus, vasopressor use, or cardiac arrest. The secondary outcome was sustained hypotension, defined as a systolic blood pressure less than 90 mm Hg and lasting greater than or equal to 30 minutes., Results: The cohort consisted of 195 episodes of acute pulmonary edema, representing 65 episodes with severe aortic stenosis (N=65) and an equal number of matched episodes with moderate aortic stenosis (N=65) and no aortic stenosis (N=65). Nitroglycerin was administered intravenously only in 70% of cases, intravenously and sublingually in 25%, and sublingually only in the remaining 5%. After adjustment for sex, initial systolic blood pressure, furosemide dose, and use of noninvasive ventilation, moderate and severe aortic stenosis were not associated with clinically relevant hypotension after receipt of nitroglycerin (adjusted odds ratio [OR] 0.97, 95% confidence interval [CI] 0.40 to 2.37 for moderate aortic stenosis; adjusted OR 0.99, 95% CI 0.41 to 2.41 for severe aortic stenosis). The incidence of clinically relevant hypotension was 26.2% for moderate and severe aortic stenosis and 23.1% in the no aortic stenosis reference group. The secondary outcome of sustained hypotension occurred in 29.2% of patients with severe aortic stenosis, 16.9% with moderate aortic stenosis, and 13.8% in the no aortic stenosis group (adjusted OR for severe aortic stenosis 2.34; 95% CI 0.91 to 6.01)., Conclusion: In this retrospective study, neither moderate nor severe aortic stenosis was associated with a greater risk of clinically relevant hypotension requiring intervention when nitroglycerin was used for acute pulmonary edema. Future studies should investigate safety and efficacy of nitroglycerin for patients with aortic stenosis because this study was limited by a small sample size and design limitations. Cautious use of nitroglycerin in patients with moderate or severe aortic stenosis and presenting with acute pulmonary edema may be a safer strategy than traditionally thought., (Copyright © 2015 American College of Emergency Physicians. Published by Elsevier Inc. All rights reserved.)

ACTERO Listeria Enrichment Media (ACTERO Listeria) is a selective medium developed for a single-step recovery and enrichment of Listeria spp. from environmental samples. Robustness testing of the ACTERO Listeria medium demonstrated good performance when minor changes were introduced to the incubation temperature and time. All 54 Listeria strains tested, representing the most frequently isolated Listeria species from food (L. monocytogenes, L. ivanovii, L. seeligeri, L. welshimeri, and L. grayi), were successfully enriched in ACTERO Listeria. None of the 30 nontarget strains tested in the exclusivity study was recovered after incubation in ACTERO Listeria. Recovery of Listeria was consistent across three independently produced lots of the ACTERO Listeria, and the prepared medium was stable for 45 days when stored at 4 degrees C in the dark. Matrix studies performed with environmental sponge samples from plastic and stainless steel surfaces demonstrated similar recovery of Listeria spp. in a single-step enrichment using ACTERO Listeria from plastic, and significantly better recovery from stainless steel surfaces when compared to the U.S. Department of Agriculture-Food Safety and Inspection Service reference method. The results of this study prove that ACTERO Listeria Enrichment Media can be effectively used in replacement of the two-step enrichment suggested by the reference method without affecting the recovery of Listeria spp. from environmental samples.

Background: Cardiac tamponade from necrotizing descending mediastinitis is a rare but life-threatening complication of cervicofacial infections., Case Report: A 49-year-old woman presented in shock with pleuretic chest pain at a small community clinic. She was transferred to our emergency department where cardiac tamponade was diagnosed and drained. Her initial complete blood count and chest radiography suggested a neoplastic process. She, however, was diagnosed with descending necrotizing mediastinitis due to group A Streptococcus. She underwent surgical drainage and recovered uneventfully. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Descending necrotizing mediastinitis can present with cardiac tamponade and a leukemoid reaction mimicking a neoplastic process. Recognizing this entity allows initiation of potentially life-saving treatments., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Clinical Question: Is lumbar puncture still needed in suspected subarachnoid hemorrhage with a negative head computed tomographic scan performed within 6 hours of headache onset?, Article Chosen: Perry JJ, Stiell IG, Sivilotti ML, et al. Sensitivity of computed tomography performed within six hours of onset of headache for diagnosis of subarachnoid haemorrhage: prospective cohort study. BMJ 2011;343:d4277., Objective: To determine whether lumbar puncture can be safely omitted after a negative head computed tomographic scan in the workup of a suspected subarachnoid hemorrhage.

The resistance of methicillin-resistant Staphylococcus aureus (MRSA) to all β-lactam classes limits treatment options for serious infections involving this organism. Our goal is to discover new agents that restore the activity of β-lactams against MRSA, an approach that has led to the discovery of two classes of natural product antibiotics, a cyclic depsipeptide (krisynomycin) and a lipoglycopeptide (actinocarbasin), which potentiate the activity of imipenem against MRSA strain COL. We report here that these imipenem synergists are inhibitors of the bacterial type I signal peptidase SpsB, a serine protease that is required for the secretion of proteins that are exported through the Sec and Tat systems. A synthetic derivative of actinocarbasin, M131, synergized with imipenem both in vitro and in vivo with potent efficacy. The in vitro activity of M131 extends to clinical isolates of MRSA but not to a methicillin-sensitive strain. Synergy is restricted to β-lactam antibiotics and is not observed with other antibiotic classes. We propose that the SpsB inhibitors synergize with β-lactams by preventing the signal peptidase-mediated secretion of proteins required for β-lactam resistance. Combinations of SpsB inhibitors and β-lactams may expand the utility of these widely prescribed antibiotics to treat MRSA infections, analogous to β-lactamase inhibitors which restored the utility of this antibiotic class for the treatment of resistant Gram-negative infections.

Despite the need for new antibiotics to treat drug-resistant bacteria, current clinical combinations are largely restricted to β-lactam antibiotics paired with β-lactamase inhibitors. We have adapted a Staphylococcus aureus antisense knockdown strategy to genetically identify the cell division Z ring components-FtsA, FtsZ, and FtsW-as β-lactam susceptibility determinants of methicillin-resistant S. aureus (MRSA). We demonstrate that the FtsZ-specific inhibitor PC190723 acts synergistically with β-lactam antibiotics in vitro and in vivo and that this combination is efficacious in a murine model of MRSA infection. Fluorescence microscopy localization studies reveal that synergy between these agents is likely to be elicited by the concomitant delocalization of their cognate drug targets (FtsZ and PBP2) in MRSA treated with PC190723. A 2.0 Å crystal structure of S. aureus FtsZ in complex with PC190723 identifies the compound binding site, which corresponds to the predominant location of mutations conferring resistance to PC190723 (PC190723(R)). Although structural studies suggested that these drug resistance mutations may be difficult to combat through chemical modification of PC190723, combining PC190723 with the β-lactam antibiotic imipenem markedly reduced the spontaneous frequency of PC190723(R) mutants. Multiple MRSA PC190723(R) FtsZ mutants also displayed attenuated virulence and restored susceptibility to β-lactam antibiotics in vitro and in a mouse model of imipenem efficacy. Collectively, these data support a target-based approach to rationally develop synergistic combination agents that mitigate drug resistance and effectively treat MRSA infections.

Connecting bacterial growth inhibitors to molecular targets at the whole-cell level is a major impediment to antibacterial development. Herein we report the design of a highly efficient and versatile bacteriophage-based mariner transposon delivery system in Staphylococcus aureus for determining inhibitor mode of action. Using bacteriophage-mediated delivery of concatameric minitransposon cassettes, we generated nonclonal transposant libraries with genome-wide insertion-site coverage in either laboratory or methicillin-resistant strain backgrounds and screened for drug resistance in situ on a single agar plate in one step. A gradient of gene-target expression levels, along with a correspondingly diverse assortment of drug-resistant phenotypes, was achieved by fitting the transposon cassette with a suite of outward-facing promoters. Using a panel of antibiotics, we demonstrate the ability to unveil not only an inhibitor's molecular target but also its route of cellular entry, efflux susceptibility and other off-target resistance mechanisms.

A novel series of trisubstituted ureas has been identified as potent and selective mPGES-1 inhibitors. These compounds are selective over other prostanoid enzymes such as PGF synthase and TX synthase. This series of inhibitors was developed by lead optimization of a hit from an internal HTS campaign. Lead compound 42 is potent in A549 cell assay (IC(50) of 0.34 μM) and in human whole blood assay (IC(50) of 2.1 μM). An efficient and versatile one-pot strategy for the formation of ureas, involving a reductive amination, was developed to generate these inhibitors., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Phenanthrene imidazoles 26 and 44 have been identified as novel potent, selective and orally active mPGES-1 inhibitors. These inhibitors are significantly more potent than the previously reported chlorophenanthrene imidazole 1 (MF63) with a human whole blood IC50 of 0.20 and 0.14 microM, respectively. It exhibited a significant analgesic effect in a guinea pig hyperalgesia model at oral doses as low as 14 mg/kg. Both active and selective mPGES-1 inhibitors (26 and 44) have a relatively distinct pharmacokinetic profile and are suitable for clinical development.

Substituted 8-arylquinoline analogs bearing alkyl-linked side chain were identified as potent inhibitors of type 4 phophodiesterase. These compounds address the potential liabilities of the clinical candidate L-454560. The pharmacokinetic profile of the best analogs and the in vivo efficacy in an ovalbumin-induced bronchoconstriction assay in conscious guinea pigs are reported.

The structure-activity relationship of a novel series of 8-biarylquinolines acting as type 4 phosphodiesterase (PDE4) inhibitors is described herein. Prototypical compounds from this series are potent and non-selective inhibitors of the four distinct PDE4 (IC(50)<10 nM) isozymes (A-D). In a human whole blood in vitro assay, they inhibit (IC(50)<0.5 microM) the LPS-induced release of the cytokine TNF-alpha. Optimized inhibitors were evaluated in vivo for efficacy in an ovalbumin-induced bronchoconstriction model in conscious guinea pigs. Their propensity to produce an emetic response was evaluated by performing pharmacokinetic studies in squirrel monkeys. This work has led to the identification of several compounds with excellent in vitro and in vivo profiles, including a good therapeutic window of efficacy over emesis.

Phenanthrene imidazole 3 (MF63) has been identified as a novel potent, selective, and orally active mPGES-1 inhibitor. This new series was developed by lead optimization of a hit from an internal HTS campaign. Compound 3 is significantly more potent than the previously reported indole carboxylic acid 1 with an A549 whole cell IC(50) of 0.42 microM (50% FBS) and a human whole blood IC(50) of 1.3 microM. It exhibited a significant analgesic effect in a guinea pig hyperalgesia model when orally dosed at 30 and 100mg/kg.

The discovery and SAR of a new series of substituted 8-arylquinoline PDE4 inhibitors are herein described. This work has led to the identification of several compounds with excellent in vitro and in vivo profiles, including a good therapeutic window of emesis to efficacy in several animal models. Typical optimized compounds from this series are potent inhibitors of PDE4 (IC(50)<1nM) and also of LPS-induced TNF-alpha release in human whole blood (IC(50)<0.5microM). The same compounds are potent inhibitors of ovalbumin-induced bronchoconstriction in conscious guinea pigs (EC(50)<0.1mg/kg ip) but require a dose of about 10mg/kg po in the squirrel monkey to produce an emetic response. From this series of compounds, 23a (L-454,560) was identified as an optimized compound.

L-826,141 [4-(2-(3,4-bis-difluromethoxyphenyl)-2-(4-(1,1,1, 3,3,3-hexafluoro-2-hydroxypropan-2-yl)-phenyl]-ethyl)-3-methylpyridine-1-oxide] is a selective and potent inhibitor of phosphodiesterase 4 (PDE4) with an IC(50) value of 0.26 to 2.4 nM for inhibition of the catalytic activity of PDE4A, B, C, and D. The cAMP elevation that can be maintained by PDE4 inhibitors attenuates the signaling cascades that lead to the production of certain cytokines. In cellular-based assays, L-826,141 transcriptionally down-regulates production of tumor necrosis factor (TNF)-alpha in peripheral blood mononuclear cell and whole blood assays with IC(50) values of 31 and 310 nM, respectively. Profiling the effect of this compound on various cytokines in the signaling cascade attenuated by cAMP elevation demonstrates that L-826,141 is also a potent inhibitor of interleukin (IL)-12, granulocyte macrophage-colony stimulating factor, and interferon (IFN)gamma (IC(50) values of 0.3-0.9 microM) as well as TNF-alpha formation. We have also shown that the PDE4 inhibitors rolipram and L-826,141 are potent inhibitors of CD3-plus CD28-stimulated IL-2 production in naive human T cells. To address the effect of PDE4 inhibitors on cytokine release from T helper (Th)1 and Th2 effector cells, we used a well characterized model in which T cells are derived from ovalbumin (323-339)-specific T cell receptor transgenic mice. L-826,141 inhibits Th0-mediated IL-2 production with an IC(35) value of 25 nM and Th1-mediated IFNgamma production with an IC(30) value of 46 nM. In contrast, L-826,141 had no significant inhibitory effect (IC(30) value > 2.5 microM) on Th2 cell-mediated IL-4 nor IL-13 production. Together, these data demonstrate that specific inhibition of PDE4 preferentially blocks the production of Th1 versus Th2 effector cytokines in vitro.

To better define the role of the various prostanoid synthases in the adjuvant-induced arthritis (AIA) model, we have determined the temporal expression of the inducible PGE synthase (mPGES-1), mPGES-2, the cytosolic PGES (cPGES/p23), and prostacyclin synthase, and compared with that of cyclooxygenase-1 (COX-1) and COX-2. The profile of induction of mPGES-1 (50- to 80-fold) in the primary paw was similar to that of COX-2 by both RNA and protein analysis. Quantitative PCR analysis indicated that induction of mPGES-1 at day 15 was within 2-fold that of COX-2. Increased PGES activity was measurable in membrane preparations of inflamed paws, and the activity was inhibitable by MK-886 to >or=90% with a potency similar to that of recombinant rat mPGES-1 (IC(50) = 2.4 microM). The RNA of the newly described mPGES-2 decreased by 2- to 3-fold in primary paws between days 1 and 15 postadjuvant. The cPGES/p23 and COX-1 were induced during AIA, but at much lower levels (2- to 6-fold) than mPGES-1, with the peak of cPGES/p23 expression occurring later than that of COX-2 and PGE(2) production. Prostacyclin (measured as 6-keto-PGF(1alpha)) was transiently elevated on day 1, and prostacyclin synthase was down-regulated at the RNA level after day 3, suggesting a diminished role of prostacyclin during the maintenance of chronic inflammation in the rat AIA. These results show that mPGES-1 is up-regulated throughout the development of AIA and suggest that it plays a major role in the elevated production of PGE(2) in this model.

Pyridazinone was found to be an excellent core template for selective COX-2 inhibitors. Two potent, selective and orally active COX-2 inhibitors, which were highly efficacious in rat paw edema and rat pyresis models, have been obtained.

Phosphodiesterase 4 (PDE4) inhibitors elevate cyclic adenosine 5'-monophosphate (cAMP), and this elevation has been shown to inhibit inflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha). Using TNF-alpha as a biomarker, we have developed transcription-based assays to examine inhibition of PDE4 activity in human and guinea pig whole blood. In vitro inhibition by PDE4 inhibitors was measured using quantitative PCR (qPCR) analysis of TNF-alpha mRNA levels in whole blood stimulated with lipopolysaccharide (LPS). The kinetics of human TNF-alpha mRNA production were analyzed and shown to be highest 4 hr following LPS stimulation. The guinea pig displayed kinetics of TNF-alpha transcription similar to those of the human. Analysis of inhibition of human TNF-alpha protein production was performed by immunoassay and shown to correlate with inhibition of transcription for three of the four compounds tested. Roflumilast was found to be 9-fold more potent for TNF-alpha inhibition in the qPCR assay than in the protein assay. The potencies of L-826,141 and roflumilast were determined in human and guinea pig whole blood by qPCR, with IC(50) values of 270 and 20 nM, respectively, in humans and 100 and 10 nM, respectively, in guinea pigs. These results show that the potency of PDE4 inhibitors can be monitored in whole blood using a transcription-based assay, and that this type of assay can be adapted to various species provided the TNF-alpha nucleotide sequence is known. The in vitro whole blood IC(50) for TNF-alpha inhibition was compared to inhibition in the ovalbumin-challenged guinea pig model of bronchoconstriction. Obtaining plasma levels at the IC(50) determined in vitro for L-826,141 and roflumilast provides significant inhibition of bronchoconstriction. This suggests that TNF-alpha can be used as a whole blood biomarker in the guinea pig for PDE4 inhibition in this inflammatory model.

Although in LLC-PK cells ATP depletion has been shown to result in alterations of cytoskeleton actin and an inhibition of Na+/H+ exchanger activity, there is little information concerning the regulation of this exchanger in the distal luminal membrane by ATP and actin filaments. The present study examined the direct effect of ATP and cytochalasin B on the Na+/H+ exchanger activity in the proximal and distal tubule luminal membranes. The presence of 100 microM ATP in the luminal membrane vesicles from rabbit proximal tubules did not influence the Ethyl Isopropyl Amiloride sensitive Na+ uptake by these membranes. In contrast, the same treatment of luminal membranes from distal tubules significantly enhanced the exchanger activity from 0.22 +/- 0.04 to 0.39 +/- 0.08 pM/microg/10 sec (P < 0.02). When ATP was replaced by its nonhydrolysable form, ATPgammas, the effect on the distal luminal membrane was strongly diminished suggesting that the action of the nucleotide implicates a phosphorylation step. Confirming this hypothesis, addition of 300-microM-Rp cAMP, a protein kinase A inhibitor, completely abolished the effect of ATP. In view of the fact that a tight relationship has been described between ATP, the cytoskeleton complex and the exchanger activity, we studied the effect of cytochalasin B on this activity. The presence of 20 microM cytochalasin B in the distal luminal membrane vesicles induced, as observed with ATP, a significant increase in the Na+ uptake. However, the actions of ATP and cytochalasin B were not additive. These results suggest that firstly, ATP and short actin filaments of the cytoskeleton regulate the distal luminal isoform through an intramembranous mechanism and secondly, a phosphorylation mechanism is, at least partially, implicated in the action of ATP. In contrast, the proximal tubule exchanger is regulated through different mechanisms., (Copyright 2001 Wiley-Liss, Inc.)

Transfection of the human cathepsin K cDNA into CHO cells results in the expression of mature catalytically active 27-kDa protein and in cells secreting the 39-kDa proenzyme form. Monensin, which neutralizes the pH of acidic organelles, was found to inhibit intracellular processing of the proenzyme and to stimulate its secretion into the culture medium. Brefeldin A caused alterations in immunofluorescence staining consistent with interference of lysosomal targeting and inhibited both intracellular processing and secretion of cathepsin K. Inhibition of glycosylation by tunicamycin also abolished cathepsin K maturation. Furthermore, the processing of the proenzyme to the mature form was abolished by a single mutation of the terminal Met(329) to Ala. The triple mutation of Ser(325), Pro(327), and Met(329) (all to Ala) inhibited both maturation and secretion, using either transient or stable expression systems. The results indicate that intracellular maturation and secretion of cathepsin K can be affected differentially by various treatments and by mutations of the C-terminal end of the protein. These results are consistent with the involvement of both the secreted proenzyme and the intracellularly processed enzyme in cathepsin K-mediated processes., (Copyright 2001 Academic Press.)

We have cloned and expressed the inducible form of prostaglandin (PG) E synthase from rat and characterized its regulation of expression in several tissues after in vivo lipopoylsaccharide (LPS) challenge. The rat PGE synthase is 80% identical to the human enzyme at the amino acid level and catalyzes the conversion of PGH(2) to PGE(2) when overexpressed in Chinese hamster ovary K1 (CHO-K1) cells. PGE synthase activity was measured using [(3)H]PGH(2) as substrate and stannous chloride to terminate the reaction and convert all unreacted unstable PGH(2) to PGF(2alpha) before high pressure liquid chromatography analysis. We assessed the induction of PGE synthase in tissues from Harlan Sprague-Dawley rats after LPS-induced pyresis in vivo. Rat PGE synthase was up-regulated at the mRNA level in lung, colon, brain, heart, testis, spleen, and seminal vesicles. Cyclooxygenase (COX)-2 and interleukin 1beta were also up-regulated in these tissues, although to different extents than PGE synthase. PGE synthase and COX-2 were also up-regulated to the greatest extent in a rat model of adjuvant-induced arthritis. The RNA induction of PGE synthase in lung and the adjuvant-treated paw correlated with a 3.8- and 16-fold induction of protein seen in these tissues by immunoblot analysis. Because PGE synthase is a member of the membrane-associated proteins in eicosanoid and glutathione metabolism (MAPEG) family, of which leukotriene (LT) C(4) synthase and 5-lipoxygenase-activating protein are also members, we tested the effect of LTC(4) and the 5-lipoxygenase-activating protein inhibitor MK-886 on PGE synthase activity. LTC(4) and MK-886 were found to inhibit the activity with IC(50) values of 1.2 and 3.2 microm, respectively. The results demonstrate that PGE synthase is up-regulated in vivo after LPS or adjuvant administration and suggest that this is a key enzyme involved in the formation of PGE(2) in COX-2-mediated inflammatory and pyretic responses.