Advances in the Use of N-Acetylcysteine in Chronic Respiratory Diseases

N-acetylcysteine (NAC) is widely used because of its mucolytic effects, taking part in the therapeutic protocols of cystic fibrosis. NAC is also administered as an antidote in acetaminophen (paracetamol) overdosing. Thanks to its wide antioxidative and anti-inflammatory effects, NAC may also be of benefit in other chronic inflammatory and fibrotizing respiratory diseases, such as chronic obstructive pulmonary disease, bronchial asthma, idiopathic lung fibrosis, or lung silicosis. In addition, NAC exerts low toxicity and rare adverse effects even in combination with other treatments, and it is cheap and easily accessible. This article brings a review of information on the mechanisms of inflammation and oxidative stress in selected chronic respiratory diseases and discusses the use of NAC in these disorders.

The Plasma Levels of 3-Hydroxybutyrate, Dityrosine, and Other Markers of Oxidative Stress and Energy Metabolism in Major Depressive Disorder

Major depressive disorder (MDD) is a serious mental disease with a pathophysiology that is not yet fully clarified. An increasing number of studies show an association of MDD with energy metabolism alteration and the presence of oxidative stress. We aimed to evaluate plasma levels of 3-hydroxybutyrate (3HB), NADH, myeloperoxidase, and dityrosine (di-Tyr) in adolescent and adult patients with MDD, compare them with healthy age-matched controls, and assess the effect of antidepressant treatment during hospitalisation on these levels. In our study, plasmatic levels of 3HB were elevated in both adolescents (by 55%; p = 0.0004) and adults (by 88%; p < 0.0001) with MDD compared to controls. Levels of dityrosine were increased in MDD adults (by 19%; p = 0.0092) but not adolescents. We have not found any significant effect of antidepressants on the selected parameters during the short observation period. Our study supports the findings suggesting altered energy metabolism in MDD and demonstrates its presence independently of the age of the patients.

Establishment of PANDA - a new human pancreatic ductal adenocarcinoma cell line with 3D cell culture technology

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive type of malignancy with one of the worst prognoses amongst any type of cancer. Surgery is applicable only to the limited number of patients with locally resectable tumors and currently represents the only curative treatment option. Treatment with chemotherapy and radiotherapy can only extend patient survival. Despite advances in conventional therapies, the five-year survival of PDAC remained largely unchanged. New in vitro and in vivo models are therefore urgently needed to investigate this type of cancer. Here, we present the establishment and characterization of a novel pancreatic cancer cell line, isolated from a patient with PDAC. Cell line abbreviated as PANDA (PANncreatic Ductal Adenocarcinoma) was established with an optimized 3D culture protocol published previously by our group. The new cancer cell line "PANDA" represents a novel in vitro approach for PDAC cancer research and new therapy testing.

Development of Sensitive and High-Throughput Liquid Chromatography-Tandem Mass Spectrometry Method for Quantification of Haloperidol in Human Plasma with Phospholipid Removal Pretreatment

Haloperidol, butyrophenone derivative, is a typical antipsychotic drug used in the treatment of schizophrenia, manic phase of bipolar disorder, and acute psychomotor agitations. According to the recent guidelines for therapeutic drug monitoring, it is strongly recommended to measure plasma level during the therapy with haloperidol. The objective of this study was to develop and validate a simple liquid chromatography-tandem mass spectrometry-based method to quantitate haloperidol in human plasma. After one-step extraction procedure using OSTROTM plate, gradient elution on Acquity UPLC BEH C18 (50 ×2.1mm, 1.7μm) column over 3.2 min was performed. The detection was conducted on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring mode in positive ionization mode with transitions at m/z 376.29 → 165.14 and m/z 380.28 → 169.17 for haloperidol and haloperidol-d4 (used as an internal standard), respectively. The method was fully validated to cover wide concentration range of 0.05-80 ng/mL in human plasma and meets the criteria for the selectivity, linearity and lower limit of detection, precision and accuracy, matrix effect, extraction recovery, carryover, dilution integrity and stability. The extraction recovery was nearly 100%, and no significant matrix effects were observed. Therefore, the method is applicable to routine therapeutic drug monitoring in patients' plasma.

Phosphodiesterase Inhibitors in Acute Lung Injury: What Are the Perspectives?

Despite progress in understanding the pathophysiology of acute lung damage, currently approved treatment possibilities are limited to lung-protective ventilation, prone positioning, and supportive interventions. Various pharmacological approaches have also been tested, with neuromuscular blockers and corticosteroids considered as the most promising. However, inhibitors of phosphodiesterases (PDEs) also exert a broad spectrum of favorable effects potentially beneficial in acute lung damage. This article reviews pharmacological action and therapeutical potential of nonselective and selective PDE inhibitors and summarizes the results from available studies focused on the use of PDE inhibitors in animal models and clinical studies, including their adverse effects. The data suggest that xanthines as representatives of nonselective PDE inhibitors may reduce acute lung damage, and decrease mortality and length of hospital stay. Various (selective) PDE3, PDE4, and PDE5 inhibitors have also demonstrated stabilization of the pulmonary epithelial-endothelial barrier and reduction the sepsis- and inflammation-increased microvascular permeability, and suppression of the production of inflammatory mediators, which finally resulted in improved oxygenation and ventilatory parameters. However, the current lack of sufficient clinical evidence limits their recommendation for a broader use. A separate chapter focuses on involvement of cyclic adenosine monophosphate (cAMP) and PDE-related changes in its metabolism in association with coronavirus disease 2019 (COVID-19). The chapter illuminates perspectives of the use of PDE inhibitors as an add-on treatment based on actual experimental and clinical trials with preliminary data suggesting their potential benefit.

Potential major depressive disorder biomarkers in pediatric population - a pilot study

Mental disorders affect 10-20 % of the young population in the world. Major depressive disorder (MDD) is a common mental disease with a multifactorial and not clearly explained pathophysiology. Many cases remain undetected and untreated, which influences patients' physical and mental health and their quality of life also in adulthood. The aim of our pilot study was to assess the prediction value of selected potential biomarkers, including blood cell counts, blood cell ratios, and parameters like peroxiredoxin 1 (PRDX1), tenascin C (TNC) and type IV collagen (COL4) between depressive pediatric patients and healthy peers and to evaluate a short effect of antidepressant treatment. In this study, 27 young depressive patients and 26 non-depressed age-matched controls were included. Blood analyses and immunological assays using commercial kits were performed. Platelet count was the only blood parameter for which the case/control status was statistically significant (p=0.01) in a regression model controlling for the age and gender differences. The results from ELISA analyses showed that the case/control status is a significant predictor of the parameters PRDX1 (p=0.05) and COL4 (p=0.009) in respective regression model considering the age and gender differences between MDD patients and controls. A major finding of this study is that values of platelet count, monocyte to lymphocyte ratio, white blood cell, and monocyte counts were assessed by the Random Forest machine learning algorithm as relevant predictors for discrimination between MDD patients and healthy controls with a power of prediction AUC=0.749.

The effect of pulmonary surfactant on the airway smooth muscle after lipopolysaccharide exposure and its mechanisms

Pulmonary surfactant has a relaxing effect on the airway smooth muscle (ASM), which suggests its role in the pathogenesis of respiratory diseases associated with hyperreactivity of the ASM, such as asthma and chronic obstructive pulmonary disease (COPD). The ASM tone may be directly or indirectly modified by bacterial wall component lipopolysaccharide (LPS). This study elucidated the effect of LPS on the ASM reactivity and the role of surfactant in this interaction. The experiments were performed using ASM of adult guinea pigs by in vitro method of tissue organ bath (ASM unexposed-healthy or exposed to LPS under in vitro conditions) and ASM of animals intraperitoneally injected with LPS at a dose 1 mg/kg of b.w. once a day during 4-day period. Variable response of LPS was controlled by cyclooxygenase inhibitor indomethacin and relaxing effect of exogenous surfactant was studied using leukotriene and histamine receptor antagonists. The exogenous surfactant has relaxing effect on the ASM, but does not reverse LPS-induced smooth muscle contraction. The results further indicate participation of prostanoids and potential involvement of leukotriene and histamine H1 receptors in the airway smooth muscle contraction during LPS exposure.

Respiratory Cilia as a Therapeutic Target of Phosphodiesterase Inhibitors

Mucociliary clearance is an essential airway defense mechanism dependent predominantly on the proper ciliary function and mucus rheology. The crucial role of cilia is evident in `a variety of respiratory diseases, as the ciliary dysfunction is associated with a progressive decline in lung function over time. The activity of cilia is under supervision of multiple physiological regulators, including second messengers. Their role is to enable a movement in coordinated metachronal waves at certain beat frequency. Ciliary function can be modulated by various stimuli, including agents from the group of beta₂ agonists, cholinergic drugs, and adenosine triphosphate (ATP). They trigger cilia to move faster in response to elevated cytoplasmic Ca²⁺ originated from intracellular sources or replenished from extracellular space. Well-known cilia-stimulatory effect of Ca²⁺ ions can be abolished or even reversed by modulating the phosphodiesterase (PDE)-mediated breakdown of cyclic adenosine monophosphate (cAMP) since the overall change in ciliary beating has been dependent on the balance between Ca²⁺ ions and cAMP. Moreover, in chronic respiratory diseases, high ATP levels may contribute to cAMP hydrolysis and thus to a decrease in the ciliary beat frequency (CBF). The role of PDE inhibitors in airway cilia-driven transport may help in prevention of progressive loss of pulmonary function often observed despite current therapy. Furthermore, administration of selective PDE inhibitors by inhalation lowers the risk of their systemic effects. Based on this review we may conclude that selective (PDE1, PDE4) or dual PDE inhibitors (PDE3/4) increase the intracellular level of cyclic nucleotides in airway epithelial cells and thus may be an important target in the development of new inhaled mucokinetic agents. Further research is required to provide evidence of their effectiveness and feasibility regarding their cilia-modulating properties.

Simultaneous determination of fluoxetine, venlafaxine, vortioxetine and their active metabolites in human plasma by LC-MS/MS using one-step sample preparation procedure

The aim of antidepressant therapy is to induce remission and prevent relapses of major depressive disorder with minimum adverse effects during the treatment. Due to high variability in metabolism, therapeutic drug monitoring is recommended as a useful tool for individualisation of the therapy. For this purpose, we have developed simple and sensitive ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for quantification of fluoxetine (FLX), venlafaxine (VEN), vortioxetine (VTX) and their active metabolites norfluoxetine (NFLX) and O-desmethylvenlafaxine (ODV). After one-step extraction procedure using OSTRO plate, analytes were separated by gradient elution on Acquity UPLC BEH C18 (50 × 2.1 mm, 1.7 μm) column with runtime 4.2 min. The detection was done on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring (MRM) mode with transitions at m/z 310.23 → 148.20 for FLX, m/z 296.23 → 134.20 for NFLX, m/z 278.31 → 121.13 for VEN, m/z 264.31 → 107.14 for ODV and m/z 299.19 → 150.05 for VTX using a positive electrospray ionisation interface. The method was successfully validated according to the European Medicine Agency guideline for the selectivity, linearity and lower limit of detection, precision and accuracy, matrix effect, extraction recovery, carryover, dilution integrity and stability over a concentration range of 1-300 ng/mL for FLX, NFLX, VEN, ODV and 0.2-100 ng/mL VTX. Extraction recovery for each analyte was > 80 %, and no significant matrix effects were observed. The developed method was employed for quantification of antidepressants in clinical samples from patients treated with either FLX, VEN, or VTX.

BMP Inhibition in the Presence of LIF Differentiates Murine Embryonic Stem Cells to Early Neural Stem Cells

Early mouse neural stem cells (NSCs) first appear in embryonic day E5.5 and express pluripotency markers Oct4, Sox2, Nanog and early neural marker Sox1. Early NSCs are a good model for understanding the role of various pathways that control initial neural commitment. However, a protocol for differentiation of mouse embryonic stem cells (ESCs) into early NSCs by adherent monolayer culture has not yet been established. Hence, in this study, we identified the combination of growth factors and small molecules that differentiated mouse ESCs into early NSCs and supported their proliferation. Leukaemia inhibitory factor (LIF) was the first factor to be tested and it was found that ESCs can differentiate into early neurogenic lineage in the presence of LIF. However, we found that the induction is weaker in the presence of LIF as compared to cells differentiated in its absence. GSK-3 inhibitor, along with BMP and TGF-β pathway inhibitor (dual SMAD inhibition), are commonly used to sequentially direct ESCs towards NSCs. However, when we used this combination, mouse ESCs failed to differentiate into early NSCs. We observed that by adding Wnt inhibitor to the combination of GSK-3 inhibitor, BMP inhibitor, TGF-β inhibitor and LIF, it was possible to differentiate ESCs into early NSCs. qRT-PCR analysis of early NSCs illustrated that they expressed key pluripotency genes Oct4 and Nanog, albeit at levels lower than non-differentiated ESCs, along with early neural markers Sox1 and Pax6.

Plasma based targeted metabolomic analysis reveals alterations of phosphatidylcholines and oxidative stress markers in guinea pig model of allergic asthma

Bronchial asthma is one of the most common, chronic respiratory diseases, characterized by reversible airway obstruction, eosinophil and Th2 infiltration, airway hyperresponsiveness and airway remodelling; with many cells and mediators involved. Metabolomics is a relatively new field in "omics" sciences enabling the identification of metabolome for better diagnostics and studying of diseases phenotype. The aim of this study was to investigate the role of targeted metabolomics study for better understanding of the bronchial asthma pathophysiology and finding potential biomarkers in experimental models of eosinophilic inflammation. Plasma level of 185 metabolites was measured with the AbsoluteIDQ™ p180 kit in guinea pigs with experimentally-induced allergic inflammation (n = 15) compared to naïve non-sensitised and non-challenged controls (n = 18). Of the 185 metabolites identified in plasma, 22 were significantly different and changed in ovalbumin sensitised animals. Plasma level of 13 phosphatidylcholines with saturated and unsaturated long-chain fatty acids, total phosphatidylcholines count, carnitine, symmetric dimethylarginine and its ratio to total unmodified arginine, and kynurenine to tryptophan ratio were found to be decreased, while phospholipase A2 activity indicator, tryptophan, taurine and ratio of methionine sulfoxide to unmodified methionine were found to be increased in sensitised guinea pigs compared to naïve controls. Targeted metabolomic analysis revealed significant differences in plasma metabolome of sensitised guinea pigs. Our observations point to the activation of inflammatory and immune pathways, as well as the involvement of oxidative stress.

Corticosteroids in Acute Lung Injury: The Dilemma Continues

Acute lung injury (ALI) represents a serious heterogenous pulmonary disorder with high mortality. Despite improved understanding of the pathophysiology, the efficacy of standard therapies such as lung-protective mechanical ventilation, prone positioning and administration of neuromuscular blocking agents is limited. Recent studies have shown some benefits of corticosteroids (CS). Prolonged use of CS can shorten duration of mechanical ventilation, duration of hospitalization or improve oxygenation, probably because of a wide spectrum of potentially desired actions including anti-inflammatory, antioxidant, pulmonary vasodilator and anti-oedematous effects. However, the results from experimental vs. clinical studies as well as among the clinical trials are often controversial, probably due to differences in the designs of the trials. Thus, before the use of CS in ARDS can be definitively confirmed or refused, the additional studies should be carried on to determine the most appropriate dosing, timing and choice of CS and to analyse the potential risks of CS administration in various groups of patients with ARDS.

Detection of resistance to anti-tuberculosis drugs in the clinical isolates of Mycobacterium tuberculosis from Slovakia through comparison between phenotypic and genetic methods and evaluation of resistance levels with clinical parameter

The incidence of tuberculosis (TB) in some countries increases continuously, especially caused by mycobacterial strains resistant to various anti-tuberculotic drugs (AT). The emergence and spread of drug-resistant tuberculosis (multidrug-resistant - MDR-TB, and extensively drug-resistant - XDR-TB) suggest the crucial role of pharmacotherapy protocol tailored to the respective patient with MDR-TB or XDR-TB (a personalized approach) and requirements for fast and precise diagnostics of the degree of resistance. The aim of this study was to characterize a molecular basis of resistance to AT, and to identify the presence of the resistance using conventional susceptibility testing and molecular genetic methods using PCR tests in Slovakia during years 2009 - 2017. Furthermore, we focused on evaluation of the relationship between the level of resistance, the clinical status, and some laboratory markers of patients with drug-resistant TB. Totally 1157 strains isolated from patients in 2009 - 2017 were tested for resistance using classical methods and in resistant strains, the molecular-genetic tests were performed. Increased incidence of recurrence, prolonged time required to culture conversion, increased mortality during treatment, plasma C-reactive protein concentrations and sedimentation rate, broader spectrum of AT used, as well as higher incidence of adverse effects (sufficiently controlled with symptomatic treatment) were observed with higher degree of resistance. Contrary, the number of patients who achieved remission decreased. Rapid and precise identification of MDR-TB or XDR-TB strains using both classical and molecular-genetic testing is an essential tool for personalized drug treatment and prevention of resistance spread and worsening. Both tests should be used for correct diagnosis of resistant TB. Higher level of resistance required more aggressive therapeutic approach, associated with adverse effects and prolongation of the culture conversion time, as well as increased risk of relapse. Effective pharmacotherapy led to significant decrease of CRP levels in all groups of patients. The most frequent adverse effects of ATs - impairment of liver and kidney functions - were effectively managed by symptomatic treatment.

Simultaneous Determination of Total Cortisol and Cortisone in Human Plasma by Liquid Chromatography-Tandem Mass Spectrometry: Method Development, Validation and Preliminary Clinical Application

Background:

Cortisol as a major glucocorticosteroid product of the adrenal cortex which has been recognized as a stress biomarker in evaluating stress related disorders for a long time. Plasma concentration of cortisol and its metabolite cortisone are usually changed in physiological and psychological tension, anxiety and depression. In order to study these changes properly, we need a sensitive, accurate and reproducible assay for plasma cortisol and cortisone determination. </P><P> Objective: The aim of this study was to develop a sensitive and robust method for the determination of total cortisol and cortisone in human plasma using mass spectrometry.

Methods:

A fast, sensitive and selective liquid chromatography-tandem mass spectrometry (LCMS/ MS) method was developed, validated, and then the levels of cortisol and cortisone were determined. Plasma samples cleanup procedure was composed of two steps: the first was a protein precipitation with 1 % formic acid in acetonitrile, and the second was an on-line solid phase extraction (SPE). Afterwards, cortisol and cortisone were separated using a C18 ACQUITY UPLC BEHTM column with a gradient elution. The mobile phase A was 0.1 % formic acid in water, the mobile phase B was 0.1 % methanol. For the detection we used a XEVO TQ-S mass spectrometer operating in the ESI positive mode.

Results:

The time of analysis was 6.5 minutes and the quantification range was 5-600 ng/mL for cortisol and cortisone, with > 94% recovery for all analytes (cortisol, cortisone and internal standards). The method was validated according to the EMA guideline for bioanalytical method validation.

Conclusion:

A simple and sensitive LC-MS/MS method was developed and validated for measurement of cortisol and cortisone in human plasma. Our findings indicate that the proposed analytical method is suitable for routine analysis.

Effects of phosphodiesterase 5 inhibitor sildenafil on the respiratory parameters, inflammation and apoptosis in a saline lavage-induced model of acute lung injury

Acute lung injury (ALI) is associated with deterioration of alveolar-capillary lining and transmigration and activation of inflammatory cells. Sildenafil, phosphodiesterase 5 (PDE5) inhibitor, inhibits degradation of cyclic guanosine monophosphate (cGMP) by competing with cGMP for binding site of PDE5. Positive effects of sildenafil treatment result from influencing proliferation of regulatory T cells and production of proinflammatory cytokines and autoantibodies as well as from modulation of platelet activation, angiogenesis, and pulmonary vasoreactivity. This study evaluated if intravenous sildenafil can influence inflammation, edema formation, apoptosis, and respiratory parameters in rabbits with a model of ALI induced by repetitive lung lavage by saline (30 ml/kg). animals were divided into 3 groups: ALI without therapy (ALI), ALI treated with sildenafil intravenously (1 mg/kg; ALI + Sil), and healthy ventilated controls (Control) which were oxygen-ventilated for 4 hours following treatment administration. during this period, respiratory parameters (ventilator pressures, lung compliance, blood gases, oxygenation indexes etc.) were regularly measured. at the end of experiment, animals were overdosed by anesthetics. The left lung was saline-lavaged and total and differential cell counts and protein content in the bronchoalveolar lavage fluid (BAL) were estimated. The right lung was used for determination of lung edema formation expressed as wet/dry lung weight ratio, for detection of inflammation and oxidative stress markers by ELISA methods, and for detection of lung epithelial cells apoptosis by TUNEL methods and level of caspase-3. Sildenafil treatment reduced leak of cells (P < 0.05), particularly of neutrophils (P < 0.001) into the lung, release of pro-inflammatory mediators (TNF-α, P < 0.001; IL-8 and IL-6, P < 0.01), level of nitrite/nitrate (P < 0.001), markers of oxidative damage (3-nitrotyrosine and malondialdehyde, both P < 0.01), lung edema formation (P < 0.01), protein content in BAL (P < 0.001), and apoptosis of epithelial cells (P < 0.01), and improved respiratory parameters. Concluding, the results indicate a future potential of PDE5 inhibitors also for the therapy of ALI.

Determination of Phosphodiesterase Inhibitors Tadalafil, Roflumilast and Roflumilast N-Oxide Using LC-MS in Guinea Pig Plasma

Phosphodiesterases are known as a super-family of 11 isoenzymes, which can exert various functions based on their organ distribution. In this work, a rapid and sensitive ultra-high performance liquid chromatography-tandem mass spectrometry method was developed for quantification of tadalafil (phosphodiesterase five inhibitor), roflumilast (RF) (phosphodiesterase four inhibitor) and its active metabolite, RF N-oxide in guinea pig plasma. Chromatographic separation was carried out on UPLC BEH C18 column (2.1 mm × 50 mm, 1.7 μm) at a flow rate 0.5 mL/min, using 0.2% formic acid in acetonitrile and 0.2% formic acid in water as mobile phases within 4 min. Detection was performed using a triple quadrupole mass spectrometer employing electrospray ionization operated in positive mode using multiple reaction monitoring mode. The method utilized deuterium labeled internal standards, and was validated according to European Medicines Agency guidelines. It showed excellent linearity in the range of 0.5-500.0 ng/mL for all analytes with coefficient of determination >0.99. The intra- and inter-day precisions (relative standard deviation %) were within 6.7%, and the recoveries were greater than 73.4%. Using this method, plasma samples from experiments of phosphodiesterase four, and five inhibitors in a model of ovalbumin-induced allergic inflammation in guinea pigs were analyzed.

Phosphodiesterase inhibitors: Potential role in the respiratory distress of neonates

Phosphodiesterases (PDEs) are a superfamily of enzymes that catalyze the hydrolysis of phosphodiester bonds of 3',5' cyclic adenosine and guanosine monophosphate (cAMP and cGMP). PDEs control hydrolysis of cyclic nucleotides in many cells and tissues. Inhibition of PDEs by selective or nonselective PDE inhibitors represents an effective targeted strategy for the treatment of various diseases including respiratory disorders. Recent data have demonstrated that PDE inhibitors can also be of benefit in respiratory distress in neonates. This article outlines the pharmacological properties of nonselective and selective PDE inhibitors and provides up-to-date information regarding their use in experimental models of neonatal respiratory distress as well as in clinical studies.

Inhibitors of phosphodiesterases in the treatment of cough

A group of 11 enzyme families of metalophosphohydrolases called phosphodiesterases (PDEs) is responsible for a hydrolysis of intracellular cAMP and cGMP. Xanthine derivatives (methylxanthines) inhibit PDEs without selective action on their single isoforms and lead to many pharmacological effects, e.g. bronchodilation, anti-inflammatory and immunomodulating effects, and thus they can modulate the cough reflex. Contrary, selective PDE inhibitors have been developed to inhibit PDE isoforms with different pharmacological effects based on their tissue expression. In this paper, effects of non-selective PDE inhibitors (e.g. theophylline) are discussed, with a description of other putative mechanisms in their effects on cough. Antitussive effects of selective inhibitors of several PDE isoforms are reviewed, focusing on PDE1, PDE3, PDE4, PDE5 and PDE7. The inhibition of PDEs suggests participation of bronchodilation, suppression of TRPV channels and anti-inflammatory action in cough suppression. Selective PDE3, PDE4 and PDE5 inhibitors have demonstrated the most significant cough suppressive effects, confirming their benefits in chronic inflammatory airway diseases associated with bronchoconstriction and cough.

Bronchodilator and Anti-Inflammatory Action of Theophylline in a Model of Ovalbumin-Induced Allergic Inflammation

Phosphodiesterases (PDEs) represent a super-family of 11 enzymes hydrolyzing cyclic nucleotides into inactive 5' monophosphates. Inhibition of PDEs leads to a variety of cellular effects, including airway smooth muscle relaxation, inhibition of cellular inflammation, and immune responses. In this study we focused on theophylline, a known non-selective inhibitor of PDEs. Theophylline has been used for decades in the treatment of chronic inflammatory airway diseases. It has a narrow therapeutic window and belongs to the drugs whose plasma concentration should be monitored. Therefore, the main goal of this study was to evaluate the plasma theophylline concentration and to determine its relevance to pharmacological effects after single and longer term (7 days) administration of theophylline at different doses (5, 10, 20, and 50 mg/kg) in guinea pigs. Airway hyperresponsiveness was assessed by repeated exposure to ovalbumin. Theophylline reduced specific airway resistance in response to histamine nebulization, measured in a double chamber body plethysmograph. A decrease in tracheal smooth muscle contractility after cumulative doses of histamine and acetylcholine was confirmed in vitro. A greater efficacy of theophylline after seven days long treatment indicates the predominance of its anti-inflammatory activity, which may be involved in the bronchodilating action.

Quantification of Theophylline in Guinea Pig Plasma by LC-MS/MS Using Hydrophilic Interaction Liquid Chromatography Stationary Phase: Method Development, Validation, and Application in Study

Theophylline has been used in the treatment of bronchial asthma and chronic obstructive pulmonary disease (COPD) for over 70 years. In order to maximize the effectiveness and safety of theophylline therapy it is important to individualize the dosage of the drug. In our study we focused on determination of theophylline concentrations in guinea pig plasma. A rapid, specific, and reliable LC-MS/MS-based method was developed and validated according to European Medicine Agency (EMA) guidelines. A hydrophilic interaction liquid chromatography (HILIC) separation mode for reduction time of sample preparation was used. The analysed sample was quantified in a positive ionization mode. Multiple reaction monitoring (MRM) using transition m/z 181.06→124.06 and m/z 187.17→127.06 was performed to quantify theophylline with deuterated internal standard ([2H6]-theophylline), respectively. Modification of collision energies was performed in parallel with chromatographic separation to further eliminate interference from the matrix. The method was validated for a range of 0.5 to 30 μg/mL of plasma sample. The intra-day and inter-day precision and accuracy of the quality control samples at low, me dium, and high concentration levels exhibited relative standard deviations (RSD) of less than 10 %. The method was successfully applied for the quantitation of theophylline in guinea pig plasma for better understanding its effects in a model of ovalbumin-induced allergic inflammation.

Effects of tadalafil (PDE5 inhibitor) and roflumilast (PDE4 inhibitor) on airway reactivity and markers of inflammation in ovalbumin-induced airway hyperresponsiveness in guinea pigs

Selective phosphodiesterase (PDE) 4 inhibitors have recently been introduced into the therapy of chronic obstructive pulmonary disease. However, suppression of airway reactivity and eosinophilic inflammation by increased intracellular cAMP could be beneficial in bronchial asthma as well. PDE5 inhibitors are used for the therapy of erectile dysfunction, pulmonary hypertension, and other cardiovascular diseases, but an expression of PDE5 in several immune cells suggests its perspectives in inflammation, as well. To bring a new information on the therapeutically relevant potential of PDE4 and PDE5 inhibitors in allergic inflammation, this study evaluated the effects of 7-days administration of PDE5 inhibitor tadalafil and PDE4 inhibitor roflumilast in experimentally-induced allergic inflammation and compared their action with effects of a corticosteroid dexamethasone. In the study, male adult guinea pigs were used. Control group was non-sensitized, while other animals were ovalbumin-sensitized over two weeks and thereafter treated intraperitoneally for 7 days with tadalafil or roflumilast (daily dose 1.0 mg/kg b.w. each), with their combination (0.5 mg/kg b.w. each), with dexamethasone (1.0 mg/kg b.w.), or with vehicle. Both tadalafil and roflumilast reduced the specific airway resistance after nebulization of histamine (a marker of in vivo airway reactivity), and decreased the in vitro airway reactivity to cumulative doses of histamine and acetylcholine in tracheal strips (significant for roflumilast) and in lung tissue strips (significant for both agents), analyzed by organ bath method. These changes were associated with decreased numbers of circulating leukocytes and eosinophils and lower production of interleukins 4 and 5, nuclear factor kappa B and tumor necrosis factor alpha in the lung. Similar effects were observed also for dexamethasone. Roflumilast and tadalafil, but not their combination with reduced doses, lowered lung TBARS, a marker of lipid oxidation. Selective PDE5 inhibition alleviated allergic airway inflammation, but it was less potent than PDE4 inhibition, whereas anti-inflammatory action of the PDE inhibitors was comparable to the effects of dexamethasone.

Effects of budesonide on the lung functions, inflammation and apoptosis in a saline-lavage model of acute lung injury

Diffuse alveolar injury, edema, and inflammation are fundamental signs of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Whereas the systemic administration of corticosteroids previously led to controversial results, this study evaluated if corticosteroids given intratracheally may improve lung functions and reduce edema formation, migration of cells into the lung and their activation in experimentally-induced ALI. In oxygen-ventilated rabbits, ALI was induced by repetitive saline lung lavage, until PaO2 decreased to < 26.7 kPa in FiO₂ 1.0. Then, one group of animals was treated with corticosteroid budesonide (Pulmicort susp inh, AstraZeneca; 0.25 mg/kg) given intratracheally by means of inpulsion regime of high-frequency jet ventilation, while another group was non-treated, and both groups were oxygen-ventilated for following 5 hours. Another group of animals served as healthy controls. After sacrifice of animals, left lung was saline-lavaged and protein content was measured and cells in the lavage fluid were determined microscopically. Right lung tissue was used for estimation of edema formation (expressed as wet/dry weight ratio), for histomorphological investigation, immunohistochemical determination of apoptosis of lung cells, and for determination of markers of inflammation and lung injury (IL-1β, IL-6, IL-8, TNF-α, IFNγ, esRAGE, caspase-3) by ELISA methods. Levels of several cytokines were estimated also in plasma. Repetitive lung lavage worsened gas exchange, induced lung injury, inflammation and lung edema and increased apoptosis of lung epithelial cells. Budesonide reduced lung edema, cell infiltration into the lung and apoptosis of epithelial cells and decreased concentrations of proinflammatory markers in the lung and blood. These changes resulted in improved ventilation. Concluding, curative intratracheal treatment with budesonide alleviated lung injury, inflammation, apoptosis of lung epithelial cells and lung edema and improved lung functions in a lavage model of ALI. These findings suggest a potential of therapy with inhaled budesonide also for patients with ARDS.

The effect of selective antagonist of H4 receptor JNJ7777120 on nasal symptoms, cough, airway reactivity and inflammation in guinea pigs

The efficacy of H4R antagonist JNJ7777120 on nasal symptoms, cough, airway resistance (Raw), inflammatory cell count in bronchoalveolar lavage (BAL) and blood in ovalbumin (OVA) induced allergic rhinitis (AR) was studied in guinea pigs. Animals (n=8) were sensitized by i.p. OVA and were repeatedly challenged with nasal OVA to induce rhinitis, seven animals were not sensitized. Animals were pre-treated with JNJ7777120 2.5 and 5mg/kg i.p. 30 min prior OVA. Cough was induced by inhalation of citric acid, Raw was measured in vivo by Pennock's method as baseline, during AR and after JNJ7777120 treatment. Leucocyte count in BAL and blood was analyzed. JNJ7777120 (5mg/kg) significantly suppressed nasal symptoms and the number of coughs. This compound significantly inhibited airway reactivity to histamine, but not methacholine. Pre-treatment with JNJ7777120 5mg/kg did not influence significantly the leucocyte count in BAL and blood except for a significant decrease in monocyte count in blood compared to the control group (p<0.05). We conclude that the antitussive action of JNJ7777120 is peripheral. The primary effect of the compound is anti-inflammatory, and the suppression of cough is a consequence of reduced airway inflammation.

N-acetylcysteine effectively diminished meconium-induced oxidative stress in adult rabbits

Since inflammation and oxidative stress are fundamental in the pathophysiology of neonatal meconium aspiration syndrome (MAS), various anti-inflammatory drugs have been used in experimental and clinical studies on MAS. This pilot study evaluated therapeutic potential of N-acetylcysteine in modulation of meconium-induced inflammation and oxidative lung injury. Oxygen-ventilated adult rabbits were intratracheally given 4 ml/kg of meconium (25 mg/ml) or saline (Sal, n = 6). Thirty minutes later, meconium-instilled animals were treated with intravenous N-acetylcysteine (10 mg/kg, Mec + NAC, n=6) or were non-treated (Mec, n = 6). All animals were oxygen-ventilated for additional 5 hours. Total and differential blood leukocyte counts were determined at baseline, and at 1, 3 and 5 h of the treatment. After sacrificing animals, left lung was saline-lavaged and total and differential cell counts in the bronchoalveolar lavage fluid were determined. Right lung was used for biochemical analyses and for estimation of wet-dry weight ratio. In lung tissue homogenate, thiobarbituric acid-reactive substances (TBARS), dityrosine, lysine-lipid peroxidation (LPO) products, and total antioxidant status (TAS) were detected. In isolated lung mitochondria, TBARS, dityrosine, lysine-LPO products, thiol group content, conjugated dienes, and activity of cytochrome c oxidase were estimated. To evaluate systemic effects of meconium instillation and NAC treatment, TBARS and TAS were determined also in plasma. To evaluate participation of eosinophils in the meconium-induced inflammation, eosinophil cationic protein (ECP) was detected in plasma and lung homogenate. Meconium instillation increased oxidation markers and ECP in the lung and decreased TAS (all P<0.05). NAC treatment reduced ECP and oxidation markers (all P<0.05, except of dityrosine in homogenate and conjugated dienes in mitochondria) and prevented a decrease in TAS (P<0.01) in lung homogenate compared to Mec group. In plasma, NAC decreased TBARS (P<0.001) and ECP, and increased TAS (both P<0.05) compared to Mec group. Concluding, N-acetylcysteine diminished meconium-induced inflammation and oxidative lung injury.

Primary cilia in gastrointestinal stromal tumors

The primary cilium is a solitary, sensory, non-motile microtubule-based structure that arises from the centrosome and is projected from the surface of most human cells. The objective of the current pilot study was to conduct an investigation of presence and frequency of cilia in gastrointestinal stromal tumors (GIST).The presence of primary cilia in GIST was evaluated in 9 patients, including 8 primary tumors and 1 liver metastasis. In 2 patients the presence of primary cilia was evaluated not only in the primary tumor, but also in recurrence: in 1 patient in recurrence without previous treatment with imatinib and in 1 patient in recurrence after treatment with imatinib. The primary cilia of GIST cells were immunofluorescently stained with primary monoclonal anti-acetylated tubulin alpha antibody and cell nuclei with DAPI.We observed 9985 nuclei of cells of GISTs and 425 primary cilia in total. The median of frequency of primary cilia in cells of GISTs in all examined samples was 4.26%, in primary tumors was 4.32% and in metastases was 3.64%, respectively. This pilot study provides the evidence of the presence of primary cilia in GISTs in different organs. Primary cilia were identified in all examined cases of GIST, including primary tumors, metastases and recurrent lesions without and with previous treatment with imatinib.

Cardiovascular effects of N-acetylcysteine in meconium-induced acute lung injury

Anti-inflammatory drugs are increasingly used for treatment of neonatal meconium aspiration syndrome (MAS), but their adverse effects are poorly known. Therefore, the aim of this study was to evaluate the effects of the antioxidant N-acetylcysteine on cardiovascular parameters in an animal model of MAS. Oxygen-ventilated rabbits were intratracheally instilled 4 mL/kg of meconium suspension (25 mg/mL) or saline. Thirty minutes later, meconium-instilled animals were given N-acetylcysteine (10 mg/kg, i.v.) or the same volume of saline. Changes in cardiovascular parameters (blood pressure, heart rate, and heart rate variability) were recorded over a 5-min course of solution administration, over 5 min after its end, and then hourly for 5 h. Oxidation markers (thiobarbituric acid-reactive substances (TBARS) and total antioxidant status) and aldosterone, as a non-specific marker of cardiovascular injury, were determined in plasma. Meconium instillation did not evoke any significant cardiovascular changes, but induced oxidative stress and elevated plasma aldosterone. N-acetylcysteine significantly reduced the mentioned markers of injury. However, its administration was associated with short-term increases in blood pressure and in several parameters of heart rate variability. Considering these effects of N-acetylcysteine, its intravenous administration in newborns with MAS should be carefully monitored.

Classical against molecular-genetic methods for susceptibility testing of antituberculotics

Tuberculosis currently belongs to rare respiratory diseases in Slovakia. However, the emergence and spread of multi-drug resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) are major challenges for global tuberculosis control, since the treatment of resistant forms creates both medical and financial problems. Cultivation methods of diagnosis are time-consuming, many times exceeding the time of the initial phase of tuberculosis treatment. Therefore, in the presented study we compared the standard procedures, based on the cultivation of mycobacteria and subsequent drug susceptibility testing to antituberculotics, with molecular-genetic methods using PCR diagnostic kits. The molecular-genetic testing enables to obtain direct and fast evidence of Mycobacterium tuberculosis, with genomic verification of resistance to the most important anti-tuberculosis drugs - isoniazid and rifampicin in MDR-TB, and ethambutol, aminoglycosides, and fluoroquinolones in XDR-TB. In 2012-2013, we confirmed 19 cases of drug-resistant tuberculosis in Slovakia. The resistance to rifampicin was confirmed in all strains with both methods. In two cases, the molecular-genetic testing did not show resistance to isoniazid, as confirmed by conventional cultivation. Furthermore, two strains demonstrating susceptibility in conventional microbiological testing to ethambutol and five strains to fluoroquinolones were verified as actually being resistant using a PCR method. Rapid diagnosis and identification of MDR-TB or XDR-TB strains using molecular-genetic testing is an essential tool for the timely and appropriate drug treatment and prevention of spread of drug resistant strains.

Short-term cardiovascular effects of selective phosphodiesterase 3 inhibitor olprinone versus non-selective phosphodiesterase inhibitor aminophylline in a meconium-induced acute lung injury

Various anti-inflammatory drugs have been used for treatment of neonatal meconium aspiration syndrome (MAS). As their adverse effects are poorly described, this study compared effects of selective phosphodiesterase (PDE) 3 inhibitor olprinone and non-selective PDE inhibitor aminophylline on cardiovascular parameters in animal model of MAS. Oxygen-ventilated rabbits were intratracheally instilled 4 mL/kg of meconium (25 mg/mL) or saline. Thirty minutes later, meconium-instilled animals were intravenously given olprinone (0.2 mg/kg) at a single dose at 0.5 h after meconium instillation, or aminophylline (2.0 mg/kg) at two doses at 0.5 and 2.5 h after meconium instillation, or were left without treatment. Cardiovascular changes were evaluated within 5 min of administration and 5 min after finishing the administration. Furthermore, respiratory and cardiovascular parameters were measured within 5 hours following treatment delivery. Oxidation markers (thiobarbituric acid-reactive substances (TBARS), and total antioxidant status) and markers of cardiovascular injury (aldosterone, gamma-glutamyltransferase (GGT), aspartate aminotransferase (AST), and alanine aminotransferase (ALT)) were determined in the plasma. Meconium instillation induced acute lung injury associated with oxidative stress, elevated aldosterone, and slightly increased GGT and AST levels. Both aminophylline and olprinone improved lung functions and reduced oxidation stress. However, the PDE inhibitors acutely increased blood pressure and heart rate, whereas heart rate variability remained higher till the end of experiment and correlated well with markers of cardiovascular injury. Considering that systemic administration of olprinone and aminophylline was accompanied by acute cardiovascular changes in the meconium-instilled animals, use of PDE inhibitors in the newborns with MAS should be carefully monitored.

Mitoxantrone ability to induce premature senescence in human dental pulp stem cells and human dermal fibroblasts

In this study we assessed the effects of the frequently used chemotherapeutic agent mitoxantrone (MTX) on dental pulp stem cells (DPSCs) and compared it with the response of human dermal fibroblasts (HDFs). DPSCs are valuable source of mesenchymal stem cells which may be extremely useful in a number of clinical applications. It is evident that both normal and tumor cells are being affected during therapy and characterization of these cells under genotoxic stress contributes to the evaluation of their safety usage. In the experiment cells were exposed to doses 5-150 nmol/l MTX. Proliferation of cells was detected by Z2 counter and viability by Vi-Cell XR using Trypan blue exclusion staining. Cell cycle analysis was determinated by flow cytometry, induction of apoptosis by monitoring the activities of caspases. The expression of key proteins was detected by Western blotting. Senescence was analyzed by activity of β-galactosidase and by detection of persisting DSBs-associated γH2AX foci. Exposure of both cell types to lower concentrations of MTX resulted in premature senescence (SIPS), which was accompanied with typical morphological changes, increased activity of senescence-associated β-galactosidase, persisting DSBs-associated γH2AX foci and cell cycle arrest in G2 phase. MTX provokes the activation of p53-p21(WAF1/Cip1) pathway in both cell types and activates cell-cycle inhibitor p16(INK4a) in HDFs, but not in DPSCs. Higher concentrations of MTX induced caspase-mediated apoptosis.

CONCLUSIONS

MTX induces apoptosis or SIPS in both cell types in dependency on MTX doses. Both pathways prevent the proliferation of cells with damaged DNA.

Dimethyl sulfoxide in a 10% concentration has no effect on oxidation stress induced by ovalbumin-sensitization in a guinea-pig model of allergic asthma

In allergic asthma, activated cells produce various substances including reactive oxygen species (ROS). As heterogenic pathophysiology of asthma results to different response to the therapy, testing novel interventions continues. Because of water-insolubility of some potentially beneficial drugs, dimethyl sulfoxide (DMSO) is often used as a solvent. Based on its antioxidant properties, this study evaluated effects of DMSO on mobilization of leukocytes into the lungs, and oxidation processes induced by ovalbumin (OVA)-sensitization in a guinea-pig model of allergic asthma. Guinea-pigs were divided into OVA-sensitized and naive animals. One group of OVA-sensitized animals and one group of naive animals were pretreated with 10% DMSO, the other two groups were given saline. After sacrificing animals, blood samples were taken and total antioxidant status (TAS) in the plasma was determined. Left lungs were saline-lavaged and differential leukocyte count in bronchoalveolar lavage fluid (BAL) was made. Right lung tissue was homogenized, TAS and products of lipid and protein oxidation were determined in the lung homogenate and in isolated mitochondria. OVA-sensitization increased total number of cells and percentages of eosinophils and neutrophils in BAL fluid; increased lipid and protein oxidation in the lung homogenate and mitochondria, and decreased TAS in the lungs and plasma compared with naive animals. However, no differences were observed in DMSO-instilled animals compared to controls. In conclusion, OVA-sensitization increased mobilization of leukocytes into the lungs and elevated production of ROS, accompanied by decrease in TAS. 10% DMSO had no effect on lipid and protein oxidation in a guinea-pig model of allergic asthma.

The influence of the PDE inhibitors on cough reflex in guinea pigs

In this study the effects of non-selective PDE inhibitors (theophylline and theobromine) and selective inhibitors of PDE 1, 3, 4 and 5 on cough, induced by citric acid, were evaluated. Inhalation of citric acid aerosol was used for cough provocation in healthy and ovalbumin-sensitized guinea pigs and the number of cough efforts was registered after visual and acoustic control by a skilled observer, with subsequent evaluation of airflow changes in a double chamber whole body plethysmograph. The pre-treatment with theophylline and theobromine (10 mg/kg b.w. intraperitoneally) decreased the number of cough efforts evoked by inhalation of citric acid aerosol (0.6 mol/l) in both healthy and ovalbumin-sensitized animals. The selective inhibitors (all 1 mg/kg b.w. intraperitoneally) of PDE1 (vinpocetin), PDE3 (cilostazol), and PDE4 (citalopram) showed antitussive effects in healthy guinea pigs. Conversely, the antitussive potential of PDE1 (vinpocetin), PDE4 (citalopram), and PDE5 (zaprinast) was observed in ovalbumin-sensitized animals. We conclude that the administration of non-selective PDE inhibitors influenced the citric acid-induced cough both in healthy and ovalbumin-sensitized guinea pigs, indicating the participation of a bronchodilating action and suppression of airway hyperreactivity in the cough suppression. With selective inhibitors, PDE4 inhibition seems to be the most effective in cough suppression, confirming its positive effects tested in chronic airway inflammatory diseases associated with bronchoconstriction and cough (Fig. 6, Ref. 27).

Influence of xanthine derivatives on cough and airway reactivity in guinea pigs

Xanthine derivatives may inhibit phosphodiesterases without selective action on their single isoforms. In this study, effects of theophylline and theobromine on cough and airway reactivity were evaluated in awake guinea pigs using double-chamber whole body plethysmograph. Pre-treatment with theophylline and theobromine (10 mg/kg, i.p.) decreased the number of cough efforts evoked by inhalation of citric acid aerosol (0.6 mol/l) in both healthy and ovalbumin-sensitized animals. Theophylline and theobromine decreased in vivo airway reactivity, i.e., specific airway resistance measured after nebulization of citric acid and histamine aerosol (10(-6) mol/l), only in ovalbumin-sensitized animals, whereas in vitro reactivity to cumulative doses of histamine and acetylcholine (10(8)-10(-3) mol/l) measured in organ chambers significantly decreased in both healthy and ovalbumin-sensitized animals, with more pronounced effect in the latter group. In conclusion, administration of theophylline and theobromine influenced the cough and airway reactivity in ovalbumin-sensitized guinea pigs, indicating the anti-inflammatory potential of xanthine derivatives.

Comparison of the effects of low-dose vs. high-dose aminophylline on lung function in experimental meconium aspiration syndrome

Due to missing information on appropriate dosing of aminophylline in meconium aspiration syndrome (MAS), this study compared effects of high-dose and low-dose aminophylline on lung function of animals with MAS. Meconium-instilled rabbits were treated by low-dose (LD, 1.0 mg/kg), or high-dose (HD, 2.0 mg/kg) aminophylline at 0.5 and 2.5 h after meconium instillation, or were left untreated. Within 5 h of oxygen ventilation, HD-aminophylline improved gas exchange, reduced pulmonary shunts and ventilatory pressures, and decreased edema formation and lung neutrophils. LD-aminophylline enhanced lung function to a lower extent than HD-aminophylline, and failed to reduce lung edema and the number of lung neutrophils. Both treatments decreased lung peroxidation, with a stronger effect of HD-aminophylline on lipid oxidation and of LD-aminophylline on protein oxidation. Tracheal reactivity to histamine decreased after HD-aminophylline, while lung tissue reactivity was more reduced after LD-aminophylline. Although LD-aminophylline showed some anti-inflammatory potential, HD-aminophylline improved most of the parameters more effectively.

Influence of selective inhibitors of phosphodiesterase 3 and 4 on cough and airway reactivity

As the administration of many antitussive drugs is often associated with adverse effects, new alternatives are evaluated in experimental and clinical conditions. The aim of this study was to assess the influence of selective inhibitors of PDE3 (cilostazol) and PDE4 (citalopram) on cough and airway reactivity. The number of cough efforts, specific airway resistance, in vitro airway reactivity, and differential blood cells count were measured in healthy and in ovalbumin-sensitized guinea pigs before and after administration of cilostazol or citalopram (1 mg/kg). Cilostazol significantly suppressed citric acid induced cough only in healthy guinea pigs, whereas citalopram in both healthy and ovalbumin-sensitized animals. Both PDE inhibitors decreased in vivo and in vitro airway reactivity to histamine and the count of monocytes and neutrophils, confirming their anti-inflammatory potential. Administration of selective PDE3 and PDE4 inhibitors may influence cough and airway reactivity in the model of ovalbumin-sensitized guinea pigs.

Combination of budesonide and aminophylline diminished acute lung injury in animal model of meconium aspiration syndrome

Combination of low-dose budesonide and low-dose aminophylline may improve lung function in reduced adverse effects compared with high-dose monotherapy. Adult rabbits intratracheally received 4 ml/kg of saline or meconium (25 mg/ml). Meconium-injured rabbits were treated at 0.5 and 2.5 h after meconium instillation by intravenous aminophylline (1.0 mg/kg), by intratracheal budesonide (0.125 mg/kg) followed by intravenous aminophylline (1.0 mg/kg), or were untreated. Although aminophylline improved some respiratory parameters, budesonide+aminophylline more effectively reduced intrapulmonary shunts and improved gas exchange, without significant cardiovascular effects. Combined treatment reduced lung edema and number of lung neutrophils to a higher extent than aminophylline alone. Both treatments reduced lung peroxidation and in vitro airway reactivity to histamine, with a better effect after aminophylline alone. Combination of budesonide and aminophylline enhanced respiratory parameters more effectively, having fewer side effects than aminophylline alone. However, no additive effect of budesonide was observed on lung peroxidation and in vitro airway reactivity.

Rapid cardiovascular effects of dexamethasone in rabbits with meconium-induced acute lung injury

Glucocorticoids may improve lung function in newborns with meconium aspiration syndrome (MAS), but information on the acute side effects of glucocorticoids in infants is limited. In this study using a rabbit model of MAS, we addressed the hypothesis that systemic administration of dexamethasone causes acute cardiovascular changes. Adult rabbits were treated with 2 intravenous doses of dexamethasone (0.5 mg/kg each) or saline at 0.5 h and 2.5 h after intratracheal instillation of human meconium or saline. Animals were oxygen-ventilated for 5 h after the first dose of treatment. Blood pressure, heart rate, and short-term heart rate variability (HRV) were analyzed during treatment, for 5 min immediately after each dose, and for the 5 h of the experiment. In the meconium-instilled animals, dexamethasone increased blood pressure, decreased heart rate, increased HRV parameters, and caused cardiac arrhythmia during and immediately after administration. In the saline-instilled animals, the effect of dexamethasone was inconsistent. In these animals, the acute effects of dexamethasone on blood pressure and cardiac rhythm were reversed after 30 min, whereas heart rate continued to decrease and HRV parameters continued to increase for 5 h after the first dose of dexamethasone. These effects were more pronounced in meconium-instilled animals. If systemic glucocorticoids are used in the treatment of MAS, cardiovascular side effects of glucocorticoids should be considered.

Re-expression of nestin in the myocardium of postinfarcted patients

Intact cardiac muscle cells in the adult heart do not express intermediate filament nestin. In this study, we report on widespread expression of intermediate filament nestin in human myocardium of patients who died from the myocardial infarction. Nestin was detected in cardiomyocytes, endothelial cells, and few interstitial cells. Elevated levels of nestin were observed in cardiac muscle cells in all specimens, although the intensity of immunoreactivity and distribution of the signal differed. The strongest immunoreactivity was observed from 4 days after myocardial infarction in the infarction border zone where nestin was distributed homogeneously in the entire sarcoplasm of cardiac muscle cells. Within the following week, nestin in immunoreactive cardiomyocytes was redistributed and restricted to small subsarcolemmal foci and to intercalated discs. Angiogenic capillaries that grew between vital nestin-positive cardiomyocytes and entered the necrotic area expressed also high levels of nestin. Nestin-positive endothelial cells were often observed in mutual interactions with nestin-positive cardiac muscle cells. These findings document a crucial role of nestin in remodeling cytoskeleton of cells in the human postinfarcted myocardium.

Opinions of medical students on the pre-graduate scientific activities--how to improve the situation?

BACKGROUND

The number of medical undergraduates taking part in Student Scientific Activities (SSA) at Jessenius Faculty of Medicine Comenius University in Slovakia remains low. The aim of this study was to discover some of the factors responsible and suggest improvements.

METHODS

An anonymous 30-item questionnaire was devised and sent to 245 medical undergraduates (UG) of the 1st, 2nd, 3rd and 5th years.

RESULTS

Foreign fellowships, postgraduate research, assistant posts at universities and financial incentives were cited as the main positive motivators for participation in UG student scientific research. Characteristics in tutors that encouraged student research were scientific knowledge, giving time to students and enthusiasm for research while poor infrastructure, tutor lack of time/interest, own time constraints, weak career motivation and lack of information were the strongest discouraging factors.

CONCLUSION

Involvement of students in SSA is influenced by many factors. To increase the number of students taking part in SSA, student research and/or continuing to Ph.D and scientific career, these factors need to be addressed by medical schools.

In vitro reactivity of urinary bladder smooth muscle in rabbits influenced by xanthine derivatives

INTRODUCTION

The contractions of urinary bladder smooth muscle are evoked by parasympathetic nervous system, with its main mediator acetylcholine. These contractions can be inhibited by two basic mechanisms--inhibition of contraction (anticholinergic drugs) or inducing the relaxation (sympathomimetics, calcium channel blockers). In this study, we investigated the effect of caffeine and theophylline--both are nonselective inhibitors of phosphodiesterase--on urinary bladder smooth muscle contractions evoked by acetylcholine.

METHODS

The reactivity of the urinary bladder smooth muscle was estimated by in vitro method using organ chambers.

RESULTS

Caffeine and theophylline caused decrease of urinary bladder smooth muscle reactivity to acetylcholine. This decrease was statistically significant only in concentrations of 10(-4) and 10(-3) mol.l(-1) of caffeine and theophylline.

CONCLUSIONS

Caffeine and theophylline significantly influenced the reactivity of urinary bladder smooth muscle in guinea pigs to acetylcholine. By comparing the influence of aminophylline we can conclude, that caffeine as well as theophylline caused significantly stronger decrease of the reactivity to acetylcholine than aminophylline only in lower concentration (Fig. 4, Ref. 30). Full Text (Free, PDF) www.bmj.sk.

Intratracheally administered corticosteroids improve lung function in meconium-instilled rabbits

Local administration of corticosteroids may diminish acute lung injury associated with meconium aspiration. Budesonide was given intratracheally in 2 doses of 0.25 mg/kg each by means of inpulsion effect of high-frequency jet ventilation 0.5 and 2.5 hours after meconium instillation to oxygen-ventilated adult rabbits. Within 5 hours after the first dose, budesonide significantly improved gas exchange and decreased right-to-left pulmonary shunts, central venous pressure, and ventilatory pressures. In addition, budesonide reduced the meconium-induced lung edema formation, airway hyperreactivity to histamine, count of neutrophils in bronchoalveolar lavage fluid associated with higher total white blood cell and neutrophil counts in the blood, and diminished oxidative modifications of proteins and lipids in lung tissue compared to non-treated meconium-instilled group. The intratracheally administered corticosteroid budesonide effectively improved pulmonary functions and alleviated changes associated with inflammation in meconium-instilled rabbits.

Evaluation of the cough reflex and airway reactivity in toluene- and ovalbumin-induced airway hyperresponsiveness

Stimulation of mechanoceptors is considered to be the major mechanism of cough. Our aim in this study was to evaluate the relationship between in vivo and in vitro airway reactivity (AR) in chemically- and antigen-induced airway hyperresponsiveness (AHR). AHR was induced chemically (toluene vapors) or via antigen (ovalbumin) in healthy guinea pigs. While toluene inhalation did not cause a significant difference in the number of cough efforts during citric acid nebulization, a significant increase in specific airway resistance after inhalation of histamine was observed, as measured in double chamber body plethysmograph. In contrast, ovalbumin led to a significant increase in both the number of cough efforts and in vivo AR. The in vitro tests confirmed the presence of increased reactivity of tracheal and lung tissue strips to histamine. However, no clear correlation between bronchoconstriction and cough reflex was found in the experimental model used for this study.