Inhibition of arachidonic acid release from cells as the biochemical action of anti-inflammatory corticosteroids

A Narrative Review of the Published Pre-Clinical Evaluations: Multiple Effects of Arachidonic Acid, its Metabolic Enzymes and Metabolites in Epilepsy

Arachidonic acid (AA), an important polyunsaturated fatty acid in the brain, is hydrolyzed by a direct action of phospholipase A2 (PLA2) or through the combined action of phospholipase C and diacylglycerol lipase, and released into the cytoplasm. Various derivatives of AA can be synthesized mainly through the cyclooxygenase (COX), lipoxygenase (LOX) and cytochrome P450 (P450) enzyme pathways. AA and its metabolic enzymes and metabolites play important roles in a variety of neurophysiological activities. The abnormal metabolites and their catalytic enzymes in the AA cascade are related to the pathogenesis of various central nervous system (CNS) diseases, including epilepsy. Here, we systematically reviewed literatures in PubMed about the latest randomized controlled trials, animal studies and clinical studies concerning the known features of AA, its metabolic enzymes and metabolites, and their roles in epilepsy. The exclusion criteria include non-original studies and articles not in English.

Efficacy of Oxytetracycline Hydrocortisone-Soaked Gauze Pack on Postoperative Sequelae in Lower Third Molar Surgery: A Prospective Study

Background Though various advancements came into the field of surgery to do the atraumatic procedure, post-operative pain, and swelling are unavoidable complications. Hence, various medicaments are packed in the extracted third molar sockets to prevent these post-operative complications. Aim The study aimed to evaluate the efficacy of oxytetracycline hydrocortisone-soaked gauze in reducing post-operative pain and swelling compared to conventional surgical procedures without any packing in patients undergoing surgical extraction of the impacted mandibular third molars. Materials and methods The study was conducted in the Department of Oral and Maxillofacial Surgery at Saveetha Dental College and Hospitals, Chennai. In this study, 50 patients were randomly included in two groups of 25 participants each. In group A, oxytetracycline hydrocortisone-soaked gauze was placed, and in group B, conventional closure was done without any pack after surgical removal of impacted mandibular third molars. Post-operative pain was assessed on days one, three, and five using a 10-point visual analog scale. Post-operative swelling was assessed on the third and seventh days using a four-point swelling measurement. Data analysis was done using SPSS (IBM Corp. Armonk, NY). A p-value less than 0.05 was considered statistically significant. Independent sample t-test was done to compare the outcomes between the two groups. Results The results demonstrated that group A (Oxytetracycline Hydrocortisone-soaked gauze) showed superior pain reduction compared to group B (conventional closure) at all post-operative intervals (P=0.001). Moreover, group A exhibited reduced swelling, resulting in higher patient satisfaction levels compared to group B on the third post-operative day (P=0.001). Conclusion It can be concluded from the study that there was a significant reduction in post-operative pain and swelling with the use of oxytetracycline hydrocortisone-soaked gauze, as it acts like a local drug delivery system in patients undergoing impacted mandibular third molar surgeries.

The dose-response effects of arachidonic acid on primary human skeletal myoblasts and myotubes

Background

Cellular inflammatory response, mediated by arachidonic acid (AA) and cyclooxygenase, is a highly regulated process that leads to the repair of damaged tissue. Recent studies on murine C2C12 cells have demonstrated that AA supplementation leads to myotube hypertrophy. However, AA has not been tested on primary human muscle cells. Therefore, the purpose of this study was to determine whether AA supplementation has similar effects on human muscle cells.

Methods

Proliferating and differentiating human myoblasts were exposed to AA in a dose-dependent manner (50-0.80 µM) for 48 (myoblasts) or 72 (myotubes) hours. Cell viability was tested using a 3-(4,5-Dimethylthiazol-2-Yl)-2,5-Diphenyltetrazolium Bromide (MTT) assay and cell counting; myotube area was determined by immunocytochemistry and confocal microscopy; and anabolic signaling pathways were evaluated by western blot and RT-PCR.

Results

Our data show that the treatment of primary human myoblasts treated with 50 µM and 25 µM of AA led to the release of PGE₂ and PGF_2α at levels higher than those of control-treated cells (p < 0.001 for all concentrations). Additionally, 50 µM and 25 µM of AA suppressed myoblast proliferation, myotube area, and myotube fusion. Anabolic signaling indicated reductions in total and phosphorylated TSC2, AKT, S6, and 4EBP1 in myoblasts at 50 µM of AA (p < 0.01 for all), but not in myotubes. These changes were not affected by COX-2 inhibition with celecoxib.

Conclusion

Together, our data demonstrate that high concentrations of AA inhibit myoblast proliferation, myotube fusion, and myotube hypertrophy, thus revealing potential deleterious effects of AA on human skeletal muscle cell health and viability.

The use of corticosteroids in the lateral sinus augmentation surgical procedure: A systematic review and meta-analysis

BACKGROUND

The lateral maxillary sinus augmentation (MSA) procedure has good predictability in terms of the success of bone regeneration with a low incidence of postoperative infections, estimated between 2% and 5.6%. Although the use of antibiotics is an established and standardized prophylactic measure for MSA procedures, the addition of corticosteroids still varies among clinician preference and clinical judgment.

PURPOSE

The aim of this systematic review was to identify whether the administration of corticosteroids during the MSA surgical procedure affects postoperative symptoms including swelling, pain, and infection rate.

MATERIALS AND METHODS

A literature search through PubMed, EMBASE, Ovid MEDLINE, and Web of Science indices, according to PICO criteria, was conducted to identify whether MSA peri-operative use of corticosteroids reduces the incidence of complications and patient morbidity. A single arm meta-analysis was performed due to the lack of randomized controlled trials (RCTs) comparing groups treated with or without peri-operative corticosteroids. The intracluster correlation co-efficient (ICC) and design effect were calculated to adjust for the clustering design.

RESULTS

In the 37 studies included, a total of 1599 patients (378 Cort, 1221 No-Cort) were analyzed. Before and after taking account of clustering, there was statistically significant effect of corticosteroids on swelling, pain, wound dehiscence, trismus, and hematoma. The complication rates postoperatively were comparable between the two study groups, however slight differences existed in the incidence of active suppuration (1.7% [95% CI 0.7-3.9] Cort vs. 3.2% [2.2-4.5] No-Cort), wound dehiscence (3.9% [1.3-11.2] Cort vs. 2.1% [1.0-4.1] No-Cort) and trismus (2.7% [0.8-8.4] Cort vs. 1.4% [0.8-2.5] No-Cort).

CONCLUSIONS

Although the event rate of the 1-to-2-week postoperative complications did not differ between the two groups, the lack of conclusive data and research comparing peri-operative corticosteroid use makes it impossible to draw definitive conclusions and more evidence and studies designed for this specific purpose are needed.

Cardiorespiratory adaptation to low-dose dexamethasone for lung disease in extremely preterm infants: A prospective echocardiographic study

The cardiovascular impact of dexamethasone (Dex) is not well understood. Most data are obtained from a 6 week, high-dose regimen, and are limited to findings of hypertension and cardiac hypertrophy. The present study ascertained the impact of low-dose Dex on cardiac indices when administered to extremely preterm infants for lung disease. A pre-post intervention prospective echocardiographic (Echo) study was undertaken, with cardiac assessments performed before and within 24 h after completion of first course of therapy (10 day regimen, cumulative 0.89 mg kg^-1 ). Thirty infants with a gestational age of 24.6 ± 1.1 weeks and birthweight of 612 ± 125 g, respectively, were studied. The age at Dex administration was 20 ± 9 days. Fractional inspired oxygen decreased from 0.7 ± 0.23 to 0.35 ± 0.14 (P < 0.001). Patent ductus arteriosus was noted in 20 infants at Echo1. At Echo2, the ductal diameter decreased from 2.16 ± 0.8 to 1.1 ± 0.8 mm (P = 0.0003), with complete closure in 7/20 (35%). A reduction in left pulmonary artery end-diastolic velocity was noted (17 ± 12 to 9 ± 10 cm s^-1 , P < 0.001). Pulmonary vascular resistance decreased (increased time to peak velocity/right ventricular ejection time, 0.2 ± 0.03 to 0.23  ± 0.03, P = 0.0001) and right ventricular systolic performance improved (tricuspid annular plane systolic excursion, 4.9 ± 0.8 to 5.5 ± 0.9 mm, P = 0.02). No significant changes in fractional shortening and left ventricular mass were noted. A significant increase in blood pressure was noted. As a percentage of pre-treatment baseline, the mean increase for systolic blood pressure was 20.3% (95% confidence interval = 14-26) on day 2 (P = 0.008). Low-dose Dex influenced cardiovascular parameters related to pulmonary circulation. KEY POINTS: Corticosteroid therapy is frequently used in preterm infants who are dependent on ventilator support. Echocardiographic studies in infants administered a 6 week course of steroids have noted left ventricular hypertrophy, outlet obstruction and hypertension, but no information is available on right heart indices. The cardiopulmonary effects of the current, significantly lesser cumulative dose (10 day regimen, commonly described as 'DART') have not been evaluated. The present study noted a significant influence on ductal and pulmonary circulation indices. Left heart architecture and function was maintained, whereas a significant but transient increase in blood pressure was noted.

A New Postoperative Regimen after CXL and PRK Using Topical NSAID and Steroids on the Open Ocular Surface

Corneal epithelium removal during photorefractive keratotomy (PRK), TransPRK, or corneal cross-linking (CXL) means that patients experience pain and inflammation after the procedure, which need to be carefully managed with topical drug regimens. One highly effective class of topical analgesics is non-steroidal anti-inflammatory drugs (NSAIDs), but these must be used carefully, as their use has been associated with delayed re-epithelialization and, in rare cases, corneal melting. However, our clinical experience has been that the concomitant use of topical corticosteroids obviates this risk. Here, we present a mechanistic explanation for our observations, our TransPRK and epithelium-off CXL protocols, and the postoperative medication regimens where topical NSAIDs are used in combination with topical steroid therapy during the first two postoperative days (where pain and inflammation levels are the highest). We detail the results of a single-center retrospective case analysis that examined eyes that underwent TransPRK (n = 301) or epithelium-off CXL (n = 576). Topical NSAID use in the first two postoperative days to control pain and inflammation after PRK/TransPRK or epithelium-off CXL, when used in combination with topical steroid therapy, does not appear to be associated with corneal melting or delayed epithelial healing. This approach may represent an improvement over current methods of handling post-surgical pain in procedures that require corneal epithelial debridement.

Anti-Inflammatory Potentials of β-Ketoester Derivatives of N-Ary Succinimides: In Vitro, In Vivo, and Molecular Docking Studies

Inflammation, being a well-known and complex pathological condition, is always a challenge to the human health. This research work was designed for a rationale-based anti-inflammatory study on β-ketoester derivatives of N-ary succinimides. The compounds (A–D) were synthesized by organocatalytic Michael addition. The compounds were initially screened for in vitro 5-lipoxygenase (5-LOX) and cyclooxygenase (COX-2) assays. For the in vivo activity, carrageenan-induced paw edema and arachidonic acid-induced ear edema tests were used. Furthermore, different in vivo pathways such as prostaglandins E2, histamine, leukotriene, and bradykinin were studied. The results were supported with molecular docking studies. Among the compounds, D (ethyl 1-(1-benzyl-2,5-dioxopyrrolidin-3-yl)-2-oxocyclohexane-1-carboxylate) at a concentration of 1000 μg/ml showed significant inhibitory effects of 83.67% and 78.12% against COX-2 and 5-LOX in comparison to celecoxib and zileuton, respectively. Similarly, compound D also showed excellent in vivo anti-inflammatory potential. Amongst all the compounds, D demonstrated excellent (55.92 ± 2.95%) anti-inflammatory potential at maximum tested dose (100 mg/kg) which accomplished the highest significance at 4 h following the carrageenan insertion and stayed considerable ( ${}^{\ast \ast \ast }P<0.001$ ) till the 5th hour of test sample injection. Compound D also exhibited excellent percent inhibition (63.81 ± 2.24%) at the highest dose in arachidonic acid-induced ear inflammation. On the basis of in vivo and in vitro results, compound D was subjected to various inflammation-causing agents such as histamine, prostaglandins E2, bradykinin, and leukotriene via the mouse paw edema test. Compound D revealed moderate effect (28.10 ± 1.64%) against histamine-induced paw edema while nonsignificant result (9.72 ± 3.125%) was marked for the bradykinin pathway. Compound D showed significance against edematogenic consequence of prostaglandin E2 (56.28–72.03%) and leukotriene (55.13 ± 2.25%) induced inflammation. In summary, our findings recommended that compound D possesses double acting anti-inflammatory properties inhibiting both COX and LOX pathways. Binding orientations and energy values computed via docking simulations support the results of the experimental in vitro evaluation.

Adult-onset hypothyroidism causes mechanical hypersensitivity due to peripheral nerve hyperexcitability based on voltage-gated potassium channel downregulation in male mice

Thyroid hormones play an important role in the central and peripheral nervous system functions. Approximately 50% of adult-onset hypothyroid patients have sensory symptoms including pain, possibly caused by peripheral neuropathy. However, the mechanism causing the pain has not been clarified. We generated an adult-onset hypothyroid model animal by administering 50 ppm propylthiouracil (PTU) for 5 weeks to male mice. Female mice were not tested in this study. Mechanical hypersensitivity, determined by the von Frey hair test, was observed during the PTU exposure and recovered after the exposure termination. The sciatic nerve compound action potential was also analyzed. Under single-pulse stimulation, no significant change in the threshold and conduction velocity was observed in the PTU-administered group. On the other hand, under train-pulse stimulation, the latency delay in the Aδ-fiber component was less in the PTU-administered group in Week 4 of PTU exposure, indicating relative hyperexcitability. Fluticasone, which is the anti-inflammatory agent with an ability to activate the voltage-gated potassium channel subfamily A (Kv1), restored the decrease in the latency change ratio by PTU exposure under the train-pulse stimulation supporting our hypothesis that Kv1 may be involved in the conductivity change. Kv1.1 protein level decreased significantly in the sciatic nerve of the PTU-administered group. These results indicate that adult-onset hypothyroidism causes mechanical hypersensitivity owing to hyperexcitability of the peripheral nerve and that reduction of Kv1.1 level may be involved in such alteration.

Do corticosteroids reduce postoperative pain following third molar intervention?

Background

Corticosteroids have been widely used by oral surgeons for reducing swelling caused by wisdom teeth surgery. However, they have not been proven to decrease pain. This study was aimed at analyzing previous studies pertaining to corticosteroids and pain reduction following wisdom teeth surgery.

Methods

The Science Direct, PubMed, and MEDLINE databases were searched for relevant journals according to a systematic search strategy (Patient Intervention Comparison Outcome Study). Randomized controlled trials published in English from 1998 to 2017 were extracted.

Results

Twenty-seven articles were included, with a total of 36 comparative cases. Methylprednisolone and dexamethasone were the most commonly used corticosteroids. Intramuscular injections of corticosteroids were optimal for pain reduction, regardless of the time of administration.

Conclusions

Corticosteroids can be used as an adjuvant for pain reduction following wisdom teeth surgery. Methylprednisolone and dexamethasone delivered via the intramuscular route is the best method for effective pain reduction. The ideal time for administration of corticosteroids is the preoperative period.

Multiday corticosteroids in cancer chemotherapy delay the diagnosis of and antimicrobial administration for febrile neutropenia: a double-center retrospective study

BACKGROUND

Medical staff should promptly administer antimicrobials to patients with febrile neutropenia (FN) to decrease the mortality related to cancer chemotherapy. Corticosteroids, which are used in cancer chemotherapy, have a fever-suppressive effect. This effect could lead to a blunt fever response and any local signs of infection, especially in patients receiving multiday corticosteroid administration. The aim of this study was to determine whether multiday corticosteroid administration in cancer chemotherapy delays the diagnosis of and antimicrobial treatment for FN.

METHODS

We conducted a double-center retrospective study in Japanese patients with FN. The patients were divided into two groups based on the corticosteroid administration method, i.e., whether administration was multiday or not. To evaluate the degree of masking on FN by corticosteroids, we assessed the correlation between body temperature variation and time of antimicrobial administration after the initiation of chemotherapy. Risk factors for delayed antimicrobial administration were identified by multiple logistic regression analysis.

RESULTS

Two hundred thirteen patients were analyzed. The median time required to body temperature reaching 37.5 °C and for antimicrobial administration was longer in the multiday group than in the non-multiday group, with 0.64 and 0.60 days (P = 0.002 and P < 0.001), respectively. Multiday corticosteroid use was identified as an independent risk factor for delayed antimicrobial administration (odds ratio = 3.94; 95% confidence interval = 1.80-8.62; P < 0.001).

CONCLUSIONS

Multiday corticosteroid administration in cancer chemotherapy delayed the diagnosis of and antimicrobial administration for FN. Furthermore, it was the only risk factor for delayed antimicrobial administration. We could thus provide evidence that the diagnosis of and antimicrobial administration for FN in patients receiving multiday corticosteroid administration should not be based on body temperature variation alone.

The characteristics of nivolumab-induced colitis: an evaluation of three cases and a literature review

BACKGROUND

The use of immune-checkpoint inhibitors in cancer treatment has become increasingly common, resulting in an increase in the incidence of related side effects. Diarrhoea and colitis have been previously documented as gastrointestinal tract-related side effects of immune-checkpoint inhibitors. Although PD-1/PD-L1 inhibitors produce fewer side effects than CTLA-4 inhibitors, diarrhoea and colitis continue to be reported. However, little is known about the endoscopic features associated with PD-1/PD-L1 inhibitors. In this report, we describe three cases of colitis induced by a PD-1 inhibitor nivolumab. These cases showed endoscopic findings characteristic of ulcerative colitis (UC). Treatment was in accordance with UC therapy, which resulted in beneficial outcomes.

CASE PRESENTATION

Three patients with lung cancer treated with nivolumab presented with diarrhoea with (case 2) or without haematochezia (cases 1 and 3). Treatment with nivolumab was ceased and colonoscopy was performed, revealing endoscopic features similar to those of UC. These patients were diagnosed with nivolumab-induced colitis. Case 1 was treated with mesalazine, whereas cases 2 and 3 were treated with corticosteroids. Subsequently, their symptoms improved.

CONCLUSIONS

Nivolumab-induced colitis exhibited similar characteristics to UC. Treatment was similar to that for UC and was successful.

Evaluating the use of corticosteroids in preventing and treating bronchopulmonary dysplasia in preterm neonates

Approximately 15 million babies worldwide are born premature, and complications of prematurity are one of the leading causes of death in neonates. Neonatal respiratory distress syndrome (NRDS) and bronchopulmonary dysplasia (BPD) are two of the most common and serious consequences of prematurity. Synthetic corticosteroids, including dexamethasone, have been central in efforts to treat and prevent BPD. There is strong evidence to show that prenatal corticosteroids reduce infant mortality and the incidence of NRDS, leading to their widespread use in obstetric units. However, data suggest that they are not as effective in reducing the incidence of BPD as NRDS, which may be due to the multifactorial pathogenesis of BPD. On the other hand, the use of postnatal corticosteroids in preterm infants is much more controversial. They have been shown to improve lung function and help in reducing the need for mechanical ventilation. These benefits, however, are associated with a range of adverse short- and long-term effects. This review will discuss the benefits and consequences of corticosteroids in treating BPD and will examine alternative treatments and future research that may improve the understanding of BPD and inform clinical practice.

Different Dosages of Corticosteroid and Routes of Administration in Mandibular Third Molar Surgery: a Systematic Review

Objectives

The objective of the present systematic review was to test the hypothesis of no difference in facial swelling, pain and trismus after surgical removal of mandibular third molar with different dosages of corticosteroids and administration routes.

Material and Methods

A MEDLINE (PubMed), Embase database and Cochrane Library search in combination with a hand-search of relevant journals was conducted by including randomized controlled trials published in English until 1^st December 2017.

Results

Seven studies fulfilled the inclusion criteria. Considerable variation in the included studies prevented meta-analysis from being performed. Preoperative submucosal injection of corticosteroids significantly diminishes facial swelling, pain and trismus compared with placebo. However, different dosages of corticosteroid and administration routes reveal contrary results indicating that administration of a higher dosage of corticosteroids do not necessarily cause a further decrease in facial swelling, pain and trismus.

Conclusions

Consequently, the optimal dosage of corticosteroids and administration route for diminishing postsurgical morbidity and improve quality of life after surgical removal of mandibular third molar is presently unknown. Therefore, further well-designed randomized clinical trials including a standardised protocol, patient-reported outcome measures and three-dimensional analysis of facial swelling is needed.

Laminar shear stress modulates endothelial luminal surface stiffness in a tissue-specific manner

OBJECTIVE

Endothelial cells form vascular beds in all organs and are exposed to a range of mechanical forces that regulate cellular phenotype. We sought to determine the role of endothelial luminal surface stiffness in tissue-specific mechanotransduction of laminar shear stress in microvascular mouse cells and the role of arachidonic acid in mediating this response.

METHODS

Microvascular mouse endothelial cells were subjected to laminar shear stress at 4 dynes/cm² for 12 hours in parallel plate flow chambers that enabled real-time optical microscopy and atomic force microscopy measurements of cell stiffness.

RESULTS

Lung endothelial cells aligned parallel to flow, while cardiac endothelial cells did not. This rapid alignment was accompanied by increased cell stiffness. The addition of arachidonic acid to cardiac endothelial cells increased alignment and stiffness in response to shear stress. Inhibition of arachidonic acid in lung endothelial cells and embryonic stem cell-derived endothelial cells prevented cellular alignment and decreased cell stiffness.

CONCLUSIONS

Our findings suggest that increased endothelial luminal surface stiffness in microvascular cells may facilitate mechanotransduction and alignment in response to laminar shear stress. Furthermore, the arachidonic acid pathway may mediate this tissue-specific process. An improved understanding of this response will aid in the treatment of organ-specific vascular disease.

MicroRNA: Dynamic Regulators of Macrophage Polarization and Plasticity

The ability of a healthy immune system to clear the plethora of antigens it encounters incessantly relies on the enormous plasticity displayed by the comprising cell types. Macrophages (MΦs) are crucial member of the mononuclear phagocyte system (MPS) that constantly patrol the peripheral tissues and are actively recruited to the sites of injury and infection. In tissues, infiltrating monocytes replenish MΦ. Under the guidance of the local micro-milieu, MΦ can be activated to acquire specialized functional phenotypes. Similar to T cells, functional polarization of macrophage phenotype viz., inflammatory (M1) and reparative (M2) is proposed. Equipped with diverse toll-like receptors (TLRs), these cells of the innate arm of immunity recognize and phagocytize antigens and secrete cytokines that activate the adaptive arm of the immune system and perform key roles in wound repair. Dysregulation of MΦ plasticity has been associated with various diseases and infection. MicroRNAs (miRNAs) have emerged as critical regulators of transcriptome output. Their importance in maintaining health, and their contribution toward disease, encompasses virtually all aspects of human biology. Our understanding of miRNA-mediated regulation of MΦ plasticity and polarization can be utilized to modulate functional phenotypes to counter their role in the pathogenesis of numerous disease, including cancer, autoimmunity, periodontitis, etc. Here, we provide an overview of current knowledge regarding the role of miRNA in shaping MΦ polarization and plasticity through targeting of various pathways and genes. Identification of miRNA biomarkers of diagnostic/prognostic value and their therapeutic potential by delivery of miRNA mimics or inhibitors to dynamically alter gene expression profiles in vivo is highlighted.

Dexamethasone injection into the pterygomandibular space in lower third molar surgery

The objective of this study was to evaluate the effects of 8mg dexamethasone injection into the pterygomandibular space on the postoperative sequelae of lower third molar surgery. A prospective, randomized, controlled, split-mouth study was designed involving 62 lower third molar extractions (31 patients). Prior to surgery, the study group received 2ml of 4mg/ml (8mg) dexamethasone injection through the pterygomandibular space following local anaesthesia; the control group received 2ml normal saline injection. Facial swelling, mouth opening, pain on a visual analogue scale (VAS), and the number of analgesics consumed were assessed. Descriptive statistics and the independent-samples t-test were used to compare the two groups at P<0.05. There was a significant reduction in swelling on day 2 postoperative in the dexamethasone group. Mouth opening was also significantly greater on day 2 in the dexamethasone group. The VAS pain score was significantly lower on the day of the operation and first postoperative day in the dexamethasone group, but did not differ significantly between the groups on the other postoperative days. The injection of 8mg dexamethasone into the pterygomandibular space was effective in reducing postoperative swelling, limited mouth opening, and pain following impacted lower third molar extraction.

The palliation of cerebral tumours with high-dose dexamethasone: a review

The historical use of corticosteroids for cerebral oedema due to malignancy is reviewed. The mechanisms for the formation and treatment of cerebral oedema are discussed and advice is given as to the clinical use of dexamethasone, including mention of adverse effects and drug interactions.

Osteoarthritis: Pathology, Mouse Models, and Nanoparticle Injectable Systems for Targeted Treatment

Osteoarthritis (OA) is a progressive, degenerative disease of articulating joints that not only affects the elderly, but also involves younger, more active individuals with prolonged participation in high physical-demand activities. Thus, effective therapies that are easy to adopt clinically are critical in limiting the societal burden associated with OA. This review is focused on intra-articular injectable regimens and provides a comprehensive look at existing in vivo models of OA that might be suitable for developing, testing, and finding a cure for OA by intra-articular injections. We first discuss the pathology, molecular mechanisms responsible for the initiation and progression of OA, and challenges associated with disease-specific targeting of OA. We proceed to discuss available animal models of OA and provide a detailed perspective on the use of mouse models in studies of experimental OA. We finally provide a closer look at intra-articular injectable treatments for OA, focusing on biomaterials-based nanoparticles, and provide a comprehensive overview of the various nanometer-size ranges studied.

Inhibitory effect of triamcinolone acetonide on synthesis of inflammatory mediators in the equine

Glucocorticoids (corticosteroids) are widely used anti-inflammatory agents in veterinary medical practice. These drugs are considered doping agents because they mask pain and thus, increase injury potential in equine athletes. They exhibit anti-inflammatory property by binding to glucocorticoids receptor (GR) to control the transcription of pro- and anti-inflammatory cytokines and enzymes involved in the synthesis of bioactive eicosanoids. To evaluate the role of triamcinolone acetonide (TA) on concentrations of bioactive eicosanoids in equine plasma, TA (0.04 mg/kg) was intravenously administered to horses. Before (0 h) and after TA administration, equine whole blood (EWB) samples were collected and challenged with either methanol (vehicle), calcium ionophore A-23187 (CI) or lipopolysaccharide (LPS) to stimulate ex-vivo synthesis of eicosanoids. Plasma concentrations of eicosanoids were quantified using LC-MS/MRM. Results showed that thromboxane B2 (TXB2) was not affected by TA administration when EWB was stimulated with CI. However, after LPS treatment, TXB2, PGE2, PGF2α and 15-(s)-HETE decreased during 2-8 h post-TA administration but recovered to concentrations which were not significantly different from those of pre-TA administration (0 h), after 24 h. When EWB was treated with CI, LTB4 was suppressed post-TA administration compared to 0 h. When EWB collected after TA administration was stimulated with LPS, LTB4 was not significantly different from those of 0 h. Administration of a therapeutic dose of TA (0.04 mg/kg, iv) in the horse suppressed biosynthesis of bioactive eicosanoids indicating the anti-inflammatory role of TA in the horse.

Pathophysiological and neurochemical mechanisms of postoperative nausea and vomiting

Clinical research shows that postoperative nausea and vomiting (PONV) is caused primarily by the use of inhalational anesthesia and opioid analgesics. PONV is also increased by several risk predictors, including a young age, female sex, lack of smoking, and a history of motion sickness. Genetic studies are beginning to shed light on the variability in patient experiences of PONV by assessing polymorphisms of gene targets known to play roles in emesis (serotonin type 3, 5-HT3; opioid; muscarinic; and dopamine type 2, D2, receptors) and the metabolism of antiemetic drugs (e.g., ondansetron). Significant numbers of clinical trials have produced valuable information on pharmacological targets important for controlling PONV (e.g., 5-HT3 and D2), leading to the current multi-modal approach to inhibit multiple sites in this complex neural system. Despite these significant advances, there is still a lack of fundamental knowledge of the mechanisms that drive the hindbrain central pattern generator (emesis) and forebrain pathways (nausea) that produce PONV, particularly the responses to inhalational anesthesia. This gap in knowledge has limited the development of novel effective therapies of PONV. The current review presents the state of knowledge on the biological mechanisms responsible for PONV, summarizing both preclinical and clinical evidence. Finally, potential ways to advance the research of PONV and more recent developments on the study of postdischarge nausea and vomiting (PDNV) are discussed.

[The influence of dexamethasone on pain after lumbar disc surgery. A double-blind study.]

Patients operated because of lumbar disc herniations (104 patients) were included in a randomized double-blind study analyzing the influence of dexamethasone versus placebo on postoperative drug requirements and the pain score on the visual analogue scale. High doses of dexamethasone had been administered: 40 mg i.v. on the night before the operation; 8 mg intraoperatively topical perineural application; 8 mg i.v. in the evening of the day of operation; 2x8 mg i.m. on days 1 and 2 postoperatively; 2x4 mg i.m. on days 3 and 4; 4 mg po on day 5 and 6 postoperatively. A significant decrease in the requirement for analgesics was found in the drug-treated group, particularly male patients, and also an impressive reduction in the lumbar pain score. In conclusion, there was good alleviation of sciatic pain in the dexamethasone-treated group of females during the 1st week after operation, but we found no evidence that the agent tested had an influence on the clinical outcome 1 month following the operation.

Corticosteroid administration in oral and orthognathic surgery: a systematic review of the literature and meta-analysis

PURPOSE

This study evaluated the effect of corticosteroid (CS) administration on edema, analgesia, and neuroregeneration in conjunction with surgical dental extraction, orthognathic surgery, and the risk of developing side effects.

MATERIALS AND METHODS

A systematic search of the literature was made. The primary predictor variable was CS administration and the outcome variables were edema, pain, and infection. A meta-analysis was performed. The risk of other side effects was evaluated through a simple review.

RESULTS

In oral surgery, most clinical trials showed a significant decrease in edema (P < .0001) after CS, and local injection of methylprednisolone > or =25 mg was expected to result in a significant decrease in edema. Regarding the analgesic effect, several clinical trials showed a decrease in pain after CS (P < .0001). Further, CS administration resulted in a slightly higher risk of infection (relative risk, 1.0041), but with a P value of .89. CS could be administered with no increased risk of infection. In orthognathic surgery, methylprednisolone > or =85 mg administered intravenously seemed sufficient to produce a significant decrease in edema, and several trials pointed toward a neuroregeneration effect, but no statistical analysis could be performed. Regarding the risk of other side effects, in oral surgery, a minimal risk of chronic adrenal suppression was seen; in orthognathic surgery, an elevated risk of avascular osteonecrosis, steroid-induced psychosis, and adrenal suppression was seen. There were no reports of decreased healing.

CONCLUSION

These findings suggest that the administration of CS in oral surgery decreases edema and pain significantly, with no higher risk of infection and with a minimum risk of other side effects.

Haemostatic parameters in Cushing's syndrome

We have studied haemostatic parameters in 12 patients with Cushing's syndrome. Three patients had prolonged bleeding times, and in all seven patients whose bleeding times were measured 3-6 months after surgical treatment the postoperative bleeding times were shorter (mean 7.5 min) than the pretreatment times (mean 12.3 min). In ADP- or adrenaline-induced aggregation the second wave was lacking in six and the degree of aggregation was borderline or subnormal in five patients. One patient had, in addition, a severe defect in collagen-induced aggregation. However, thromboxane B2 production of the platelets from both endogenous and exogenous arachidonic acid was unaffected. Factor VIII:C, RAg and Rcof activities were all elevated, and in patients with severe disease F VIIIR:Ag and F VIII:Rcof activities were markedly more elevated than F VIII:C activity. The changes in both primary haemostasis and in factor VIII activities correlated clearly with the clinical severity of the disease.

Regulation of pulmonary arachidonic acid metabolism by anti-inflammatory steroids

Enzymes in cells from many tissues including the lung metabolize arachidonic acid to a variety of highly active local hormones such as prostaglandins and 'slow-reacting substances'. Many of these play a part in the inflammatory response which follows injury or trauma or, in the case of slow-reacting substance, asthmatic bronchoconstriction. Both non-steroidal and steroidal anti-inflammatory drugs inhibit the formation of some or all of these products. The non-steroidal drugs block prostaglandin formation but not the formation of products such as slow-reacting substances. The steroids block the formation of all products. Their mechanism of action, investigated in the guinea-pig perfused lung, involved inhibition of arachidonic acid liberation, probably by suppression of phospholipase activity. To achieve this steroids must first bind to receptors in lung tissue and initiate de novo RNA and protein synthesis. This culminates in the synthesis or secretion by some cells in the lung of a polypeptide of mol.wt. 10 000-15 000 with potent anti-phospholipase properties. The generation of this factor could partly explain why steroids are so effective in the treatment of many types of inflammatory disease, and in particular why they are so efficacious against asthma.

cPGES/p23 is required for glucocorticoid receptor function and embryonic growth but not prostaglandin E2 synthesis

A number of studies have identified cytosolic prostaglandin E(2) synthase (cPGES)/p23 as a cytoplasmic protein capable of metabolism of prostaglandin E(2) (PGE(2)) from the cyclooxygenase metabolite prostaglandin endoperoxide (PGH(2)). However, this protein has also been implicated in a number of other pathways, including stabilization of the glucocorticoid receptor (GR) complex. To define the importance of the functions assigned to this protein, mice lacking detectible cPGES/p23 expression were generated. cPGES/p23(-/-) pups die during the perinatal period and display retarded lung development reminiscent of the phenotype of GR-deficient neonates. Furthermore, GR-sensitive gluconeogenic enzymes are not induced in the prenatal period. However, unlike GR-deficient embryos, cPGES/p23(-/-) embryos are small and a proliferation defect is observed in cPGES/p23(-/-) fibroblasts. Analysis of arachidonic acid metabolites in embryonic tissues and primary fibroblasts failed to support a function for this protein in PGE(2) biosynthesis. Thus, while the growth retardation of the cPGES/p23(-/-) pups and decreased proliferation of primary fibroblasts identify functions for this protein in addition to GR stabilization, it is unlikely that these functions include metabolism of PGH(2) to PGE(2).

Tamoxifen and the Rafoxifene analog LY117018: their effects on arachidonic acid release from cells in culture and on prostaglandin I2 production by rat liver cells

BACKGROUND

Tamoxifen is being used successfully to treat breast cancer. However, tamoxifen also increases the risk of developing endometrial cancer in postmenopausal women. Raloxifene also decreases breast cancer in women at high risk and may have a lower risk at developing cancer of the uterus. Tamoxifen has been shown to stimulate arachidonic acid release from rat liver cells. I have postulated that arachidonic acid release from cells may be associated with cancer chemoprevention.

METHODS

Rat liver, rat glial, human colon carcinoma and human breast carcinoma cells were labelled with [3H] arachidonic acid. The release of the radiolabel from these cells during incubation with tamoxifen and the raloxifene analog LY117018 was measured. The prostaglandin I2 produced during incubation of the rat liver cells with microM concentrations of tamoxifen and the raloxifene analog was quantitatively estimated.

RESULTS

Tamoxifen is about 5 times more effective than LY117018 at releasing arachidonic acid from all the cells tested. In rat liver cells only tamoxifen stimulates basal prostaglandin I2 production and that induced by lactacystin and 12-O-tetradecanoyl-phorbol-13-acetate. LY117018, however, blocks the tamoxifen stimulated prostaglandin production. The stimulated prostaglandin I2 production is rapid and not affected either by preincubation of the cells with actinomycin or by incubation with the estrogen antagonist ICI-182,780.

CONCLUSIONS

Tamoxifen and the raloxifene analog, LY117018, may prevent estrogen-independent as well as estrogen-dependent breast cancer by stimulating phospholipase activity and initiating arachidonic acid release. The release of arachidonic acid and/or molecular reactions that accompany that release may initiate pathways that prevent tumor growth. Oxygenation of the intracellularly released arachidonic acid and its metabolic products may mediate some of the pharmacological actions of tamoxifen and raloxifene.

Dexamethasone promotes toxicity in U937 cells exposed to otherwise nontoxic concentrations of peroxynitrite: pivotal role for lipocortin 1-mediated inhibition of cytosolic phospholipase A2

Pretreatment with dexamethasone (Dex) was not toxic for U937 cells but caused a rapid lethal response upon subsequent exposure to otherwise nontoxic concentrations of peroxynitrite. This effect was not associated with enhanced formation of hydrogen peroxide taking place after peroxynitrite and was shown previously to play a pivotal role in the ensuing lethal response. Further analyses revealed that although Dex did not affect cytosolic phospholipase A(2) (cPLA(2)) expression, it markedly reduced the extent of arachidonic acid (AA) release mediated by peroxynitrite-dependent stimulation of cPLA(2). This event, as well as the enhanced toxicity, was abolished by mifepristone, a glucocorticoid receptor antagonist. The outcome of various approaches, using phospholipase A(2) inhibitors, cPLA(2) antisense oligonucleotide-transfected cells, and supplementation with exogenous AA, led to the demonstration that inhibition of cPLA(2) activity is causally linked to the increased susceptibility to peroxynitrite caused by Dex. Finally, the effects of Dex were shown to be mediated by enhanced expression of lipocortin 1 (LC1), a cPLA(2) inhibitory protein. These results indicate that Dex promotes toxicity in U937 cells exposed to otherwise nontoxic concentrations of peroxynitrite and that this event is causally linked to enhanced expression of LC1 leading to inhibition of cPLA(2). Thus, the increased lethal response arises because of LC1-dependent impairment of the AA-induced cytoprotective mechanism triggered by peroxynitrite.

Varicella pneumonia: another 'steroid responsive' pneumonia?

Varicella-zoster virus (VZV) pneumonitis remains an often-fatal complication of VZV infection. Antiviral agents and supportive care are widely accepted therapies. Cautious use of corticosteroids in life-threatening VZV pneumonitis may be justified. Appropriate patient selection factors are as yet unidentified and the decision to commence corticosteroid therapy in this setting is clinical.

Epinephrine--via activation of p38-MAPK--abolishes the effect of aspirin on platelet deposition to collagen

The mechanism by which epinephrine enhances experimental thrombosis in the presence of aspirin is poorly understood. In this study, we set to explore, in aspirinised platelet-rich plasma (PRP), the effect of epinephrine (100 nmol/l) on platelet deposition to immobilised collagen and the subsequent involvement of several intracellular pathways. Under these experimental conditions, which allow platelet aggregation on top of the collagen-adherent platelets, epinephrine increased platelet deposition by 55-86%. This enhancement could be specifically prohibited by the alpha(2A)-adrenoceptor antagonist, atipamezole, the p38 mitogen-activated protein kinase (p38MAPK) inhibitor SB203580, and the cytosolic phospholipase A(2) (cPLA(2)) inhibitor, mepacrine. The effect of epinephrine coincided with increased phosphorylation of p38MAPK and cPLA(2) and with arachidonic acid (AA) release from platelet membrane. We conclude that epinephrine enhanced platelet deposition on collagen in aspirinised PRP via a mechanism dependent on both free AA in platelet cytosol (released by cPLA(2)) and p38MAPK.

Experimental induction of chronic borreliosis in adult dogs exposed to Borrelia burgdorferi-infected ticks and treated with dexamethasone

OBJECTIVE

To develop a method to experimentally induce Borrelia burgdorferi infection in young adult dogs.

ANIMALS

22 healthy Beagles.

PROCEDURE

All dogs were verified to be free of borreliosis. Twenty 6-month-old dogs were exposed to Borrelia burgdorferi-infected adult ticks and treated with dexamethasone for 5 consecutive days. Two dogs not exposed to ticks were treated with dexamethasone and served as negative-control dogs. Clinical signs, results of microbial culture and polymerase chain reaction (PCR) testing, immunologic responses, and gross and histologic lesions were evaluated 9 months after tick exposure.

RESULTS

Predominant clinical signs were episodic pyrexia and lameness in 12 of 20 dogs. Infection with B burgdorferi was detected in microbial cultures of skin biopsy specimens and various tissues obtained during necropsy in 19 of 20 dogs and in all 20 dogs by use of a PCR assay. All 20 exposed dogs seroconverted and developed chronic nonsuppurative arthritis. Three dogs also developed mild focal meningitis, 1 dog developed mild focal encephalitis, and 18 dogs developed perineuritis or rare neuritis. Control dogs were seronegative, had negative results for microbial culture and PCR testing, and did not develop lesions.

CONCLUSIONS AND CLINICAL RELEVANCE

Use of this technique successfully induced borreliosis in young dogs. Dogs with experimentally induced borreliosis may be useful in evaluating vaccines, chemotherapeutic agents, and the pathogenesis of borreliosis-induced arthritis.

Vitamin A status and postnatal dexamethasone treatment in bronchopulmonary dysplasia

OBJECTIVE

Vitamin A (retinol) plays an important role in epithelial regeneration during recovery from lung injury in bronchopulmonary dysplasia (BPD). Dexamethasone is used in the postnatal treatment of very low birth weight (VLBW) neonates with BPD. To test the hypothesis that the vitamin A status is critical for the beneficial pulmonary response to dexamethasone, we performed a prospective cohort study in which we characterized the changes in plasma concentrations of vitamin A and retinol-binding protein (RBP) in response to dexamethasone, and correlated these changes with the pulmonary outcome.

METHODS

VLBW neonates (birth weight <1350 g, gestational age <31 weeks, postnatal age >10 days), who had presumptive diagnosis of severe BPD and need for high ventilatory support (fraction of inspired oxygen >/=.6, mean airway pressure >/=7 cm H(2)O), were treated with a seven-day course of dexamethasone (.5 mg/kg/d x 2 days,.25 mg/kg/d x 2 days,.1 mg/kg/d x 3 days). Plasma concentrations of vitamin A and RBP were determined sequentially at baseline, and during and after dexamethasone treatment. Pulmonary response to dexamethasone was graded daily using a composite ventilation score. The changes in plasma vitamin A and RBP concentrations were compared between infants with a positive (beneficial) pulmonary response to dexamethasone and those with a negative response.

RESULTS

Among 23 infants studied, 13 showed a positive pulmonary response to dexamethasone, as indicated by successful weaning from supplemental oxygen and mechanical ventilation, whereas 10 showed a negative response. A significant, yet short-term, increase in plasma concentrations of both vitamin A and RBP was observed in most infants treated with dexamethasone. The plasma vitamin A and RBP responses to dexamethasone tended to be higher in infants with a positive pulmonary response than in those with a negative response. Accounting for gender, a vitamin A response with each 10.0 microg/dL increment in plasma vitamin A concentration was associated with a 60% increase in the odds favoring a positive pulmonary response to dexamethasone.

CONCLUSION

Postnatal dexamethasone treatment in VLBW neonates with BPD induces a significant, yet short-term, increase in plasma concentrations of both vitamin A and RBP. This increase probably results from endogenous mobilization of vitamin A from the liver. Our data suggest that the beneficial pulmonary response to dexamethasone in infants with BPD is influenced, at least in part, by the vitamin A status, and that gender plays a role in this response.vitamin A, dexamethasone, bronchopulmonary dysplasia.

Experimental infection of ponies with Borrelia burgdorferi by exposure to Ixodid ticks

Seven specific-pathogen-free (SPF) ponies, 1-5 years old, were exposed to Borrelia burgdorferi-infected adult ticks while being treated with dexamethasone over 5 consecutive days. One SPF pony (pony No. 178) was first exposed to laboratory-reared nymphs without B. burgdorferi infection and 3 weeks later was exposed to B. burgdorferi-infected adult ticks with concurrent dexamethasone treatment for 5 consecutive days. Four uninfected ponies treated with dexamethasone, exposed to laboratory-reared ticks without B. burgdorferi infection served as uninfected controls. Clinical signs, bacteriologic culture, polymerase chain reaction (PCR) for bacterial DNA, immunologic responses, and gross lesions and histopathologic changes were investigated during the experiment or at necropsy 9 months after tick exposure. In all of the seven challenged ponies, infection with B. burgdorferi was detected from monthly skin biopsies and various tissues at postmortem examination by culture and by PCR. However, pony No. 178 exposed to laboratory-reared nymphs (without B. burgdorferi infection) and challenged with B. burgdorferi-infected adult ticks 2 months later did not develop a B. burgdorferi infection. All of the infected ponies seroconverted. Control ponies and pony No. 178 were negative by culture, PCR, and serology. Except for skin lesions, we failed to induce any significant histopathologic changes in this study. This is the first report of successful tick-induced experimental infection in ponies by exposure to B. burgdorferi-infected ticks. This Lyme disease model will be very useful to evaluate efficacy of vaccines against the Lyme agent and the effect of antibiotic therapy on horses infected with B. burgdorferi.

Prednisolone interferes with neutrophil adhesion and neutrophil mediated endothelial injury

Adhesion of leukocytes to vascular endothelium is a crucial step in inflammation. This interaction may result in damage of the endothelial cells (EC). We evaluated the effects of prednisolone on adhesive interactions between human polymorphonuclear neutrophil granulocytes (PMN) and human umbilical vein endothelial cells (HUVEC) as well as PMN mediated cytotoxicity to HUVEC (as release of 51chromium), mediated by N-formyl-methionyl-leucyl-phenylalanine (fMLP), lipoxin A4 (LXA4), and the calcium ionophore A23187 in vitro. Prednisolone dose-dependently interfered with adhesion and cytotoxicity induced by fMLP. Prednisolone (at 10 microM) led to a 39% reduction of adhesion and an almost complete inhibition of cytotoxicity, mainly by effects on the PMN. Prednisolone also interfered with cytotoxicity induced by LXA4 by effects on PMN as well as on HUVEC. Adhesion and cytotoxicity induced by the calcium ionophore A23187 was not affected in any way by prednisolone. Thus, in these in vitro models of vasculitis, prednisolone interferes with adhesive and cytotoxic interactions induced by receptor-dependent agonists. These protective effects of prednisolone might explain some of the beneficial effects of glucocorticoids in the treatment of vasculitis.

Use of corticosteroids and the outcome of infants with bronchopulmonary dysplasia

Ventilator-dependent premature infants are often treated with dexamethasone. Several trials showed that steroids while improve pulmonary compliance and facilitate extubation, some treated infants may have adverse effects, such as alterations of growth curves. We conducted this retrospective study to evaluate the effects of steroids on mechanical ventilation, oxygen therapy, hospital length stay and mortality, in ventilator-dependent infants with bronchopulmonary dysplasia (BPD) (defined as the need of oxygen supplementation at 28 days of life). Twenty-six newborns with BPD were evaluated during 9 - 42 days postpartum (mean = 31 days) and were divided into two groups: Group I - 14 newborns that did not receive dexamethasone, and Group II - 12 newborns that received dexamethasone at 14 - 21 days of life. Dexamethasone was given at a dose of 0.25 mg per kilogram of body weight twice daily intravenously for 3 days, after which the dose was tapered.

RESULTS

There were no statistically significant differences in the mean length of mechanical ventilation (Group I - 37 days, Group II - 35 days); oxygen supplementation (Group I - 16 days, Group II - 29 days); hospital stay (Group I - 72 days, Group II - 113 days); mortality (Group I - 35.7%, Group II - 41.6%). At birth, Group II was lighter (BW: Group I - 1154 grams +/- 302, Group II - 791 grams +/- 165; p < 0.05) and smaller (height: Group I - 37.22 cm +/- 3.3, Group II - 33.5 +/- 2.4; p< 0.05) than Group I. At 40 weeks, there were no statistically significant differences between groups in relation to anthropometric measurements.

CONCLUSIONS

The use of corticosteroids in bronchopulmonary dysplasic infants may influence the somatic growth during its use. However, after its suspension, a recovery seems to occur, suggesting that its influence could be transitory.

Dexamethasone alters arachidonate release from human epithelial cells by induction of p11 protein synthesis and inhibition of phospholipase A2 activity

The effect of the glucocorticosteroid, dexamethasone, on arachidonic acid (AA) release and on protein levels of p11 and cytosolic phospholipase A2 (cPLA2) was studied in two epithelial cell lines, HeLa cells and BEAS-2B cells. Dexamethasone treatment of HeLa cells and BEAS-2B cells increased cellular p11 protein and mRNA levels in a time- and dose-dependent manner. It had little effect on levels of cPLA2 protein. In order to determine if increased p11 protein expression resulted in increased interaction between p11 and cPLA2, anti-cPLA2 antibodies were used to immunoprecipitate p11.cPLA2 complexes and Western blots of the immunoprecipitate were used to detect p11. In cells treated with dexamethasone, more p11 was detected in the anti-cPLA2 immunoprecipitate compared with control cells. Dexamethasone treatment of HeLa cells prelabeled with [3H]AA decreased the release of [3H]AA under basal conditions and after stimulation with the calcium ionophore A23187 (10(-6) M). In order to determine if altering the p11 protein levels in HeLa cells independent of glucocorticosteroid treatment could also produce an effect on [3H]AA release, cells were stably transfected with plasmids expressing either p11 antisense mRNA or p11 mRNA. Cloned HeLa cells expressing p11 antisense mRNA exhibited less cellular p11 protein compared with control cells and greater [3H]AA release compared with cells transfected with a control vector. Cloned HeLa cells stably transfected with a p11 expression vector exhibited increased p11 cellular protein and diminished [3H]AA release under basal conditions and in response to A23187. Therefore, dexamethasone alteration of epithelial cell AA release may be due in part to induction of p11 protein expression.

Inhibition of the synthesis of eicosanoid-like substances in a human oral cancer cell line by interferon-gamma and eicosapentaenoic acid

The objectives were to examine the production of eicosanoids in a Chinese human oral cancer cell line (OEC-M1) and to test the effects of interferon-gamma (IFN-gamma), eicosapentaenoic acid (EPA) and enzyme inhibitors on this biosynthesis. The eicosanoids were identified by reverse phase-high performance liquid chromatography. Two predominant peaks appeared in the chromatograms. One compound (P-1) was identified by ultraviolet absorption at a lambda(max) of 278nm with shoulders at 272 and 284nm. The other compound (P-2) was identified by ultraviolet absorption at a lambda(max) of 284 nm with shoulders at 278 and 290 nm. The production of P- was significantly inhibited by the addition of IFN-gamma (200 and 400 U/ml), and EPA (10 to 40 microM). It was only partially inhibited (p < 0.05) by indomethacin (INDO) (0.5 and 1 microM), nordihydroguaiaretic acid (NDGA) (30 and 60 microM/ml), and eicosa-5,8,11,14-tetraynoic acid (ETYA) (20-60 microM). It was almost completely inhibited by indomethacin (2 and 3 microM), and dexamethasone (0.6 and 6 microM). The production of P-2 was almost completely inhibited by IFN-gamma (200 and 400 U/ml), and partially inhibited (p < 0.05) by EPA (10 and 20 microM), NDGA (30 and 60 microM), ETYA (20 and 40 microM), dexamethasone (0.6 and 6 microM). The production of both peaks was significantly reduced by excluding arachidonic acid (AA), and almost completely inhibited by heating at 100 degrees C for 10 min during incubation. These results demonstrate that two eicosanoid-like compounds are synthesized by the OEC-M cell line and that their production can be modulated by IFN-gamma, EPA, indomethacin, NDGA, ETYA, and dexamethasone.

Role of fever in disease

Infection, trauma, and injury result in a stereotypical response that includes loss of food appetite, increased sleepiness, muscle aches, and fever. For thousands of years fever was considered a protective response, and fevers were induced by physicians to combat certain infections. But with the advent of antipyretic drugs, physicians started to reduce fevers, and fever therapy was virtually abandoned. As a result of (1) studies on the evolution of fever, (2) further understanding of just how tightly the process of fever is regulated, and (3) detailed studies on how fever affects host morbidity and mortality, the view of fever as a host defense response has reemerged. However, data indicate that not all fevers are protective and that high fevers are maladaptive. These issues are discussed in the context of the evolution of host defense responses versus modern medical technology. In short, we speculate that patients who would not have survived severe sepsis in the past are now being kept alive and that the occasionally high fevers seen in these patients may be maladaptive.

Corticosteroids in life-threatening varicella pneumonia

BACKGROUND

Varicella pneumonia that results in respiratory failure or progresses to the institution of mechanical ventilation carries a significant morbidity and mortality despite intensive respiratory support and antiviral therapy. There has been no reported study of the role of corticosteroids in life-threatening varicella pneumonia.

DESIGN AND METHODS

This was an uncontrolled retrospective and prospective study of all adult patients with a diagnosis of varicella pneumonia who were admitted to the ICUs of the Johannesburg group of academic hospitals in South Africa between 1980 and 1996. Patient demographics, clinical and laboratory features, necessity for mechanical ventilation, and complications were reviewed. The outcome and therapy of varicella pneumonia was evaluated with particular reference to the use of corticosteroids. Patients with comorbid disease and those already taking immunosuppressive agents were excluded. Key endpoints included length of ICU and hospital stay and mortality.

MEASUREMENTS AND RESULTS

Fifteen adult patients were evaluated, six of whom received corticosteroids in addition to antiviral and supportive therapy. These six patients demonstrated a clinically significant therapeutic response. They had significantly shorter hospital (median difference, 10 days; p<0.006) and ICU (median difference, 8 days; p=0.008) stays and there was no mortality, despite the fact that they were admitted to the ICU with significantly lower median ratios between PaO2 and fraction of inspired oxygen than those patients (n=9) who did not receive corticosteroid therapy (86.5 vs 129.5; p=0.045).

CONCLUSION

When used in addition to appropriate supportive care and early institution of antiviral therapy, corticosteroids appear to be of value in the treatment of previously well patients with life-threatening varicella pneumonia. The observations presented in this study are important and should form the basis for a randomized controlled trial, as no other relevant studies or guidelines are available.

Human lung fibroblasts release chemokinetic activity for monocytes constitutively

We determined whether human lung fibroblasts (HLFs) might release mediators that are responsible for monocyte chemokinetic activity (MCA) constitutively. HLF supernatant fluids showed MCA in a time-dependent manner (P < 0.001). Checkerboard analysis of 24- and 72-h supernatant fluids showed that the activity was chemokinetic. Partial characterization of 24- and 72-h supernatant fluids revealed that the mediators released after 24 h were predominantly composed of lipid-soluble activity, and MCA was blocked by lipoxygenase inhibitors. The mediators released after 72 h were predominantly trypsin sensitive and blocked by cycloheximide. Molecular-sieve column chromatography identified four peaks of MCA. A polyclonal antibody to monocyte chemoattractant protein-1 (MCP-1) inhibited MCA by 20% after 24 h and by 40% after 72 h. Granulocyte-macrophage colony-stimulating factor (GM-CSF) and transforming growth factor-beta (TGF-beta) antibodies attenuated MCA released after 72 h by 30 and 10%, respectively. These antibodies inhibited corresponding molecular-weight peaks separated by molecular-sieve column. The concentrations of MCP-1, GM-CSF, and TGF-beta were 4,698 +/- 242, 26.8 +/- 3.8, and 550 +/- 15 pg/ml, respectively. A leukotriene B4 (LTB4)-receptor antagonist attenuated the total MCA and the lowest molecular weight peak of MCA. The concentrations of LTB4 were 153.4 +/- 12.4 (24 h) and 212 +/- 16.6 (72 h) pg/ml. These findings suggest that HLFs may modulate the recruitment of monocytes into the lung by releasing MCP-1, GM-CSF, TGF-beta, and LTB4 constitutively.