Diclofenac Prolongs Repolarization in Ventricular Muscle with Impaired Repolarization Reserve

Background: The aim of the present work was to characterize the electrophysiological effects of the non-steroidal anti- inflammatory drug diclofenac and to study the possible proarrhythmic potency of the drug in ventricular muscle. Methods: Ion currents were recorded using voltage clamp technique in canine single ventricular cells and action potentials were obtained from canine ventricular preparations using microelectrodes. The proarrhythmic potency of the drug was investigated in an anaesthetized rabbit proarrhythmia model. Results: Action potentials were slightly lengthened in ventricular muscle but were shortened in Purkinje fibers by diclofenac (20 mM). The maximum upstroke velocity was decreased in both preparations. Larger repolarization prolongation was observed when repolarization reserve was impaired by previous BaCl 2 application. Diclofenac (3 mg/kg) did not prolong while dofetilide (25 mg/kg) significantly lengthened the QT c interval in anaesthetized rabbits. The addition of diclofenac following reduction of repolarization reserve by dofetilide further prolonged QT c . Diclofenac alone did not induce Torsades de Pointes ventricular tachycardia (TdP) while TdP incidence following dofetilide was 20%. However, the combination of diclofenac and dofetilide significantly increased TdP incidence (62%). In single ventricular cells diclofenac (30 mM) decreased the amplitude of rapid (I Kr ) and slow (I Ks ) delayed rectifier currents thereby attenuating repolarization reserve. L-type calcium current (I Ca ) was slightly diminished, but the transient outward (I to ) and inward rectifier (I K1 ) potassium currents were not influenced. Conclusions: Diclofenac at therapeutic concentrations and even at high dose does not prolong repolarization markedly and does not increase the risk of arrhythmia in normal heart. However, high dose diclofenac treatment may lengthen repolarization and enhance proarrhythmic risk in hearts with reduced repolarization reserve

STUDY OF FENNEL SEED GERMINATION (FOENICULUM VULGARE VAR. AZORICUM)

Fennel (Foeniculum vulgare) is a flowering plant species in the celery family Apiaceae or Umbelliferae. It is a hardy, perennial herb with yellow flowers and feathery leaves, indigenous from the shores of the Mediterranean, widely naturalized in many parts of the world, especially on dry soils near the sea-coast and on riverbanks. Florence fennel Foeniculum vulgare Azoricum is a cultivar group with inflated leaf bases which form a bulb-like structure. This experiment aimed the germination fennel seed, as a result of qualitative and quantitative processes, which determine the transition of seed from latent life to active life, resulting in development of a new plant. Seed germination depends on both internal and external conditions. Germination is epigeal and fennel seed normally germinates in 10-14 days depending mainly on the weather following sowing. The experiences made that the preparation SM (produced by Research and Development Center for Biostimulators "BIOS" Cluj-Napoca) in concentration of 0.05%, in case of treating seeds for 3 h, has a positive influence on seeds germination, compared to untreated water control

Mechanisms of ventricular rate adaptation as a predictor of arrhythmic risk.

Background: Protracted QT interval (QTI) adaptation to abrupt heart rate (HR) changes has been identified as a clinical arrhythmic risk marker. This study investigates the ionic mechanisms of QTI rate adaptation and its relationship to arrhythmic risk. Methods and Results: Computer simulations and experimental recordings in human and canine ventricular tissue were used to investigate the ionic basis of QTI and action potential (AP) duration (APD) to abrupt changes in HR with a protocol commonly used in clinical studies. Time for 90% QTI adaptation is 3.5 min in simulations, in agreement with experimental and clinical data in human. APD adaptation follows similar dynamics, being faster in midmyocardial cells (2.5 min) than in endocardial/epicardial cells (3.5 min). Both QTI and APD adapt in two phases following an abrupt HR change: a fast initial phase with time constant 2 min driven by [Na(+)]i dynamics. Alterations in [Na(+)]i dynamics due to Na(+)/K(+) pump (INaK) inhibition result in protracted rate adaptation, and is associated with increased proarrhythmic risk, as indicated by AP triangulation and faster ICaL recovery from inactivation, leading to formation of early afterdepolarizations (EADs). Conclusions: This study suggests that protracted QTI adaptation could be an indicator of altered [Na(+)]i dynamics following INaK inhibition as it occurs in patients with ischemia or heart failure. Increased risk of cardiac arrhythmias in patients with protracted rate adaptation may be due to increased risk of EAD formation. Key words: action potentials, ventricles, ion channels, arrhythmia

Mechanisms of ventricular rate adaptation as a predictor of arrhythmic risk

Background: Protracted QT interval (QTI) adaptation to abrupt heart rate (HR) changes has been identified as a clinical arrhythmic risk marker. This study investigates the ionic mechanisms of QTI rate adaptation and its relationship to arrhythmic risk. Methods and Results: Computer simulations and experimental recordings in human and canine ventricular tissue were used to investigate the ionic basis of QTI and action potential (AP) duration (APD) to abrupt changes in HR with a protocol commonly used in clinical studies. Time for 90% QTI adaptation is 3.5 min in simulations, in agreement with experimental and clinical data in human. APD adaptation follows similar dynamics, being faster in midmyocardial cells (2.5 min) than in endocardial/epicardial cells (3.5 min). Both QTI and APD adapt in two phases following an abrupt HR change: a fast initial phase with time constant 2 min driven by [Na(+)]i dynamics. Alterations in [Na(+)]i dynamics due to Na(+)/K(+) pump (INaK) inhibition result in protracted rate adaptation, and is associated with increased proarrhythmic risk, as indicated by AP triangulation and faster ICaL recovery from inactivation, leading to formation of early afterdepolarizations (EADs). Conclusions: This study suggests that protracted QTI adaptation could be an indicator of altered [Na(+)]i dynamics following INaK inhibition as it occurs in patients with ischemia or heart failure. Increased risk of cardiac arrhythmias in patients with protracted rate adaptation may be due to increased risk of EAD formation. Key words: action potentials, ventricles, ion channels, arrhythmia

The Legacy of Prof. Constantin Arseni. The Medical Architect Behind the Romanian School of Neurosurgery

douã decenii de la regretata trecere în nefiinåã a Acad. Prof. Dr. Constantin Arseni autorii realizeazã o trecere în revistã a activitãåii acestuia surprinzând totodatã modul în care a evoluat de-a lungul timpului AEcoala Româneascã de Neurochirurgie sub grija pãrinteascã a ilustrului neurochirurg. Mânat de o tenacitate incredibilã, Acad. Prof. Dr. Constantin Arseni a reuaeit nu numai sã creeze prima clinicã de neurochirurgie complet autonomã din România ci aei sã o ducã la cele mai înalte standarde academice aei aetiinåifice ale vremii dotând-o cu cele mai noi mijloace tehnice disponibile aei construind o bibliotecã pe care orice universitate de medicinã din lume ar fi invidioasã. Capodopera Acad. Prof. Dr. Constantin Arseni, cel mai mare spital cu profil neurochirurgical din Europa (la vremea respectivã), fusese conceput sã funcåioneze ca un institut de cercetare dedicat sistemului nervos central, însã odata cu prabuaeirea Uniunii Sovietice aei cãderea cortinei de fier Europa a fost marcatã de reforme iar ideea institutului dedicat creierului a fost abandonatã de autoritãåi, iar spitalul care astãzi îi poartã numele (Spitalul Bagdasar-Arseni) s-a metamorfozat într-un centru multidisciplinar dedicat urgenåelor neurochirurgicale aei traumatice. Cuvinte cheie: neurochirurgie, Constantin Arseni, Dumitru Bagdasar, Harvey Cushing, istoria medicinei Abstract The personality of Prof. Dr. Constantin Arseni (1912Arseni ( -1994 is without any doubt a key point in any discussion regarding the history of the Romanian School of Neurosurgery. Now at two decades since the regretted passing-away of Prof. Arseni the authors present several pieces of data regarding the early beginnings of neurosurgery in Romania and how this discipline has evolved over time in our country. Driven by an incredible tenacity Professor Constantin Arseni managed not only to create the first completely independent clinic of neurosurgery in Romania, but also to keep it continuously updated with the latest bibliographic and technological resources available at the time. Professor Arseni's masterpiece, the largest neurosurgical hospital in Europe (at the time of its construction) was supposed to be a completely autonomous institute dedicated to surgery on the human central nervous system. As the Iron Curtain fell and Europe was marked by continuous reforms, the idea of an institute dedicated to the brain was abandoned by the authorities and a multidisciplinary hospital dedicated to neurosurgical emergencies and trauma was born

Assessing the Indoor Pollutants Effect on Ornamental Plants Leaves by FT-IR Spectroscopy

Air pollution has become a mass phenomenon, a major and global problem of modern society, affecting billions of people and environment. People are exposed to various levels of pollutants not just in the outdoor environment, but also in indoors. The quality of life and well-being of employees can be increased by incorporating ornamental plants in the work environment. Among the great variety of plants species able to remove/reduce indoor air pollutants Dracaena deremensis, Sansevieria trifasciata and Ficus elastica were hereby investigated. Their ability to remove chemical pollutants was evaluated in real-life conditions and the changes induced by the environmental stress on the structure and biochemical composition of the plants leaves were evidenced by the Fourier transform infrared spectroscopy. The most pronounced concentration decrease was noticed for the CO₂ (58.33% removed concentration), whereas the mean value of the removed concentration of other chemical pollutants was of ≈ 25%. The Fourier transform infrared spectra analysis revealed that, although the plants are subjected to the chemical pollutants action, they maintain the structure by adjusting their metabolism. A decrease in the overall protein contribution in the amide bands and an increase of the bands assigned to polysaccharide vibrations, illustrate the consequences of the pollution action. Moreover, the chlorophyll presence is evidenced in the IR spectra of all samples by the bands around 1040, 1445, 1620, and 1735 cm^{-1}. The results show that the Fourier transform infrared spectra are an important source of information for the rapid characterization of the chemical structure of the biological systems under environmental stress