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Beat Frequency (beat + frequency)
Kinds of Beat Frequency Selected AbstractsAlternans in QRS Amplitude During Ventricular TachycardiaPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 2 2002PHILIPPE MAURY MAURY, P., et al.: Alternans in QRS Amplitude During Ventricular Tachycardia. Although the value of T wave alternans as an index of electrical instability has been extensively investigated, little is known about QRS alternans during VT. Intracardiac electrograms of 111 episodes of spontaneous monomorphic regular VT retrieved from implantable defibrillators in 25 patients were retrospectively selected. Three beat series, representing the total amplitudes and amplitudes from baseline to summit and from baseline to lower point of 16 or 32 successive QRS complexes before deliverance of electrical therapy were generated for each episode. Spectral analysis was then performed using the fast Fourrier transform. VT was considered as alternans if the magnitude of the spectral power at the 0.5-cycle/beat frequency was greater than the mean ± 3 SD of the noise in at least one of the three spectral curves. QRS alternans was present in 23 (20%) of 111 episodes and in 9 (36%) of 25 patients. Alternans was not related to the VT cycle length, QRS duration, QRS amplitude, signal amplification, nor to clinical variables. Alternans was more frequently detected in unipolar configuration and when a higher number of complexes was included in analysis. Failure of antitachycardia pacing was more frequent in case of alternans VT (50% vs 75% success in non-alternans VT, P = 0.05). Spontaneous termination before deliverance of therapy occurred in 16 nonalternans VT but never in alternans episodes (P = 0.02). Alternans in QRS amplitude is a relatively common finding during VT and could be associated with failure of antitachycardia pacing and lack of spontaneous termination. Lower efficacy of electrical therapies in case of QRS alternans must be confirmed in a way to improve the effectiveness of antitachycardia pacing. [source] Cardiac disorders in farmed adult brown trout, Salmo trutta L.JOURNAL OF FISH DISEASES, Issue 4 2000C Mercier During summer in Brittany, France, sea farmed brown trout, Salmo trutta L., regularly experience a high mortality rate which is associated, at least in part, with cardiac disorders (aneurysms and infarcts). The present study is preliminary to a more extensive research programme, the objective of which is to determine to what extent the physiological performance of the cardiovascular system of brown trout is affected by the environmental conditions the fish experience in farm cages. We conducted a 2-week in situ experiment during which the heart rate of eight sea water acclimatized individuals was telemetered using acoustic tags. During the experimental period, water temperature ranged from 16.0 to 17.6 °C. Water oxygen saturation was above 80% at all times and salinity was very high (35.5,) but stable. Although they were unfed and not active, seven of out the eight tagged animals displayed near maximum heart beat frequencies, which ranged between 83 and 98 beats per minute (bpm). On the other hand, the eighth animal exhibited medium-range heart rates (50,70 bpm). Using phase delay maps, we established that the maximum heart rate of brown trout at 17 °C was in the range of 96,100 bpm. This result suggests that in our experimental conditions, the heart rate of most of our inactive fish was between 85 and 100% of maximum myocardial performance. We hypothesize that the cardiac failures observed in brown trout during summer are most likely a result of strenuous workloads imposed on the cardiovascular system by a combination of elevated temperature, high salinity and possibly season-related decreased hypo-osmoregulatory abilities. [source] Na+/Ca2+ exchanger modulates the flagellar wave pattern for the regulation of motility activation and chemotaxis in the ascidian spermatozoaCYTOSKELETON, Issue 10 2006Kogiku Shiba Abstract Ion channels and ion exchangers are known to be important participants in various aspects of sperm physiology, e.g. motility activation, chemotaxis, the maintenance of motility and the acrosome reaction in the sperm. We report here on a role of the K+ -independent Na+/Ca2+ exchanger (NCX) on ascidian sperm. Reverse-transcriptase PCR reveals that the NCX is expressed in the testis while immunoblotting and immunolocalization demonstrate that the NCX exists on the sperm in the ascidian Ciona savignyi and C. intestinalis. A potent blocker of the NCX, KB-R7943 was found to block sperm-activating and -attracting factor (SAAF)-induced motility activation, sperm motility and sperm chemotaxis. We further analyzed the effects of this blocker on motility parameters such as the flagellar waveform, curvature, beat frequency, amplitude and wavelength of the sperm flagella. Inhibition of the NCX caused two distinct effects: a low concentration of KB-R7943 induced symmetric bending, whereas a high concentration of KB-R7943 resulted in asymmetric flagellar bending. These findings suggest that the NCX plays important roles in the regulation of SAAF-induced sperm chemotaxis, motility activation and motility maintenance in the ascidian. This study provides new information toward an understanding of Ca2+ transport systems in sperm motility and chemotaxis. Cell Motil. Cytoskeleton 2006. © 2006 Wiley-Liss, Inc. [source] Microtubule sliding movement in tilapia sperm flagella axoneme is regulated by Ca2+/calmodulin-dependent protein phosphorylationCYTOSKELETON, Issue 8 2006Masaya Morita Abstract Demembranated euryhaline tilapia Oreochromis mossambicus sperm were reactivated in the presence of concentrations in excess of 10,6 M Ca2+. Motility features changed when Ca2+ concentrations were increased from 10,6 to 10,5 M. Although the beat frequency did not increase, the shear angle and wave amplitude of flagellar beating increased, suggesting that the sliding velocity of microtubules in the axoneme, which represents dynein activity, rises with an increase in Ca2+. Thus, it is possible that Ca2+ binds to flagellar proteins to activate flagellar motility as a result of the enhanced dynein activity. One Ca2+ -binding protein (18 kDa, pI 4.0), calmodulin (CaM), was detected by 45Ca overlay assay and immunologically. A CaM antagonist, W-7, suppressed the reactivation ratio and swimming speed, suggesting that the 18 kDa Ca2+ -binding protein is CaM and that CaM regulates flagellar motility. CaMKIV was detected immunologically as a single 48 kDa band in both the fraction of low ion extract of the axoneme and the remnant of the axoneme, suggesting that CaMKIV binds to distinct positions in the axoneme. It is possible that CaMKIV phosphorylates the axonemal proteins in a Ca2+/CaM-dependent manner for regulating the dynein activity. A 32P-uptake in the axoneme showed that 48, 75, 120, 200, 250, 380, and 400 kDa proteins were phosphorylated in a Ca2+/CaM kinase-dependent manner. Proteins (380 kDa) were phosphorylated in the presence of 10,5 M Ca2+. It is possible that an increase in Ca2+ induces Ca2+/CaM kinase-dependent regulation, including protein phosphorylation for activation/regulation of dynein activity in flagellar axoneme. Cell Motil. Cytoskeleton 2006. © 2006 Wiley-Liss, Inc. [source] Does pregnancy affect swimming performance of female Mosquitofish, Gambusia affinis?FUNCTIONAL ECOLOGY, Issue 3 2002I. Plaut Summary 1.,The cost of reproduction due to limiting of the reproductive female's locomotion capability has been suggested many times, but has rarely been directly examined, especially in fishes. Here, the effect of pregnancy on swimming performance in the viviparous Mosquitofish, Gambusia affinis, was studied. 2.,Eight females of G. affinis were isolated, each in a separate aquarium, and critical swimming speed (Ucrit), body mass (BM) and cross-section area were measured every 5 days from the beginning of the pregnancy until 2,4 days after parturition. 3.,Swimming kinematics (tail beat frequency and amplitude) was measured in non-pregnant and pregnant females at different swimming speeds. 4.,BM increased during pregnancy from 0·47 ± 0·13 g to 0·72 ± 0·19 g, and the cross-section area also increased during pregnancy from 0·21 ± 0·06 cm2 to 0·32 ± 0·07 cm2. Ucrit decreased from 25·0 ± 1·3 cm s,1 before pregnancy to 20·1 ± 1·5 cm s,1 just before parturition, and returned to 24·7 ± 1·4 cm s,1 2,4 days after parturition. Interindividual variation was repeatable and reflects real differences among individuals. 5.,Swimming kinematics was not affected by pregnancy. 6.,The results suggest that reductions in Ucrit are probably because of aerobic constraints and not necessarily due to hydrodynamic changes resulting from changing in body form or plasticity. Moreover, the reduction in Ucrit is, potentially, a ,cost of reproduction' owing to decrease in the ability to gain food during pregnancy in G. affinis females. [source] Increased intracellular [dATP] enhances cardiac contraction in embryonic chick cardiomyocytesJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 6 2008Brenda Schoffstall Abstract Although ATP is the physiological substrate for cardiac contraction, cardiac contractility is significantly enhanced in vitro when only 10% of ATP substrate is replaced with 2,-deoxy-ATP (dATP). To determine the functional effects of increased intracellular [dATP] ([dATP]i) within living cardiac cells, we used hypertonic loading with varying exogenous dATP/ATP ratios, but constant total nucleotide concentration, to elevate [dATP]i in contractile monolayers of embryonic chick cardiomyocytes. The increase in [dATP]i was estimated from dilution of dye added in parallel with dATP. Cell viability, average contractile amplitude, rates of contraction/relaxation, spontaneous beat frequency, and Ca2+ transient amplitude and kinetics were examined. At total [dATP]i above ,70 µM, spontaneous contractions ceased, and above ,100 µM [dATP]i, membrane blebbing was also observed, consistent with apoptosis. Interestingly, [dATP]i of ,60 µM (,40% increase over basal [dATP]i levels) enhanced both amplitude of contraction and the rates of contraction and relaxation without affecting beat frequency. With total [dATP]i of ,60 µM or less, we found no significant change in Ca2+ transients. These data indicate that there is an "optimal" concentration of exogenously loaded [dATP]i that under controlled conditions can enhance contractility in living cardiomyocytes without affecting beat frequency or Ca2+ transients. J. Cell. Biochem. 104: 2217,2227, 2008. © 2008 Wiley-Liss, Inc. [source] Effects of sediment eluates and extracts from differently polluted small rivers on zebrafish embryos and larvaeJOURNAL OF FISH BIOLOGY, Issue 1 2002M. Strmac The effects on newly fertilized eggs, embryos and larvae of zebrafish Danio rerio following exposure to sediment samples from the more heavily contaminated River Körsch, southern Germany, occurred earlier and were more prominent than in samples from the less contaminated Krähenbach. Dose- and time-related effects following exposure to Körsch sediment eluates and extracts included: (1) hatching failure and subsequent death of larvae exposed to undiluted aqueous sediment eluates and reduced hatching rates at sediment extract concentrations 0·0125%; (2) increased mortality after exposure to 25 and 50% dilutions of aqueous sediment eluates, and dilutions of 0·00625% sediment extracts; (3) reduction of heart beat frequency for 50% dilutions of sediment eluates and concentrations of 0·025% extracts; (4) increased frequency of heart and yolk sac oedema after exposure to 0·0125% sediment extracts. Since adverse effects of sediment extracts observed in zebrafish laboratory tests correlated with reproductive failure in natural populations of brown trout Salmo trutta f. fario in the severely polluted River Körsch, early life stages tests with zebrafish appear to be a suitable tool to assess the contamination rate of natural sediments. [source] In-vitro nasal drug delivery studies: comparison of derivatised, fibrillar and polymerised collagen matrix-based human nasal primary culture systems for nasal drug delivery studiesJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 11 2001Remigius Uchenna Agu The aim of this study was to establish a collagen matrix-based nasal primary culture system for drug delivery studies. Nasal epithelial cells were cultured on derivatised (Cellagen membrane CD-24), polymerised (Vitrogen gel) and fibrillar (Vitrogen film) collagen substrata. Cell morphology was assessed by microscopy. The cells were further characterised by measurement of ciliary beat frequency (CBF), transepithelial resistance (TER), permeation of sodium fluorescein, mitochondrial dehydrogenase (MDH) activity and lactate dehydrogenase (LDH) release upon cell exposure to sodium tauro-24, 25 dihydrofusidate (STDHF). Among the three collagen substrata investigated, the best epithelial differentiated phenotype (monolayer with columnar/cuboidal morphology) occurred in cells grown on Cellagen membrane CD-24 between day 4 and day 11. Cell culture reproducibility was better with Cellagen membrane CD-24 (90%) in comparison with Vitrogen gel (70%) and Vitrogen film (< 10%). TER was higher in cells grown on Vitrogen gel than on Cellagen membrane CD-24 and Vitrogen film. The apparent permeability coefficient (Papp × 10,7 cm s,1) of sodium fluorescein in these conditions was 0.45 ± 0.08 (Vitrogen gel) and 1.91 ± 0.00 (Cellagen membrane CD-24). Except for LDH release, CBF and cell viability were comparable for all the substrata. Based on MDH activity, LDH release, CBF, TER and permeation studies, Cellagen membrane CD-24- and Vitrogen gel-based cells were concluded to be functionally suitable for in-vitro nasal drug studies. Vitrogen film-based cultures may be limited to metabolism and cilio-toxicity studies. [source] Alcohol Stimulates Ciliary Motility of Isolated Airway Axonemes Through a Nitric Oxide, Cyclase, and Cyclic Nucleotide-Dependent Kinase MechanismALCOHOLISM, Issue 4 2009Joseph H. Sisson Background:, Lung mucociliary clearance provides the first line of defense from lung infections and is impaired in individuals who consume heavy amounts of alcohol. Previous studies have demonstrated that this alcohol-induced ciliary dysfunction occurs through impairment of nitric oxide (NO) and cyclic nucleotide-dependent kinase-signaling pathways in lung airway ciliated epithelial cells. Recent studies have established that all key elements of this alcohol-driven signaling pathway co-localize to the apical surface of the ciliated cells with the basal bodies. These findings led us to hypothesize that alcohol activates the cilia stimulation pathway at the organelle level. To test this hypothesis we performed experiments exposing isolated demembranated cilia (isolated axonemes) to alcohol and studied the effect of alcohol-stimulated ciliary motility on the pathways involved with isolated axoneme activation. Methods:, Isolated demembranated cilia were prepared from bovine trachea and activated with adenosine triphosphate. Ciliary beat frequency, NO production, adenylyl and guanylyl cyclase activities, cAMP- and cGMP-dependent kinase activities were measured following exposure to biologically relevant concentrations of alcohol. Results:, Alcohol rapidly stimulated axoneme beating 40% above baseline at very low concentrations of alcohol (1 to 10 mM). This activation was specific to ethanol, required the synthesis of NO, the activation of soluble adenylyl cyclase (sAC), and the activation of both cAMP- and cGMP-dependent kinases (PKA and PKG), all of which were present in the isolated organelle preparation. Conclusions:, Alcohol rapidly and sequentially activates the eNOS,NO,GC,cGMP,PKG and sAC,cAMP, PKA dual signaling pathways in isolated airway axonemes. These findings indicate a direct effect of alcohol on airway cilia organelle function and fully recapitulate the alcohol-driven activation of cilia known to exist in vivo and in intact lung ciliated cells in vitro following brief moderate alcohol exposure. Furthermore, these findings indicate that airway cilia are exquisitely sensitive to the effects of alcohol and substantiate a key role for alcohol in the alterations of mucociliary clearance associated with even low levels of alcohol intake. We speculate that this same axoneme-based alcohol activation pathway is down regulated following long-term high alcohol exposure and that the isolated axoneme preparation provides an excellent model for studying the mechanism of alcohol-mediated cilia dysfunction. [source] Smoke Exposure Exacerbates an Ethanol-Induced Defect in Mucociliary Clearance of Streptococcus pneumoniaeALCOHOLISM, Issue 5 2005Elizabeth A. Vander Top Background: Alcoholics and smokers are particularly susceptible to pulmonary infections caused by Streptococcus pneumoniae, the pneumococcus. Infection begins when pneumococci colonizing the nasopharynx are aspirated into the lower respiratory tract. The major host defense against this movement is the mucociliary clearance apparatus. Both cigarette smoke and ethanol (EtOH) exposure alter ciliary beating and protein kinase activity in the respiratory mucosa in vitro, but their effects on bacterial clearance in the intact animal have not been determined. Methods: Male Sprague Dawley rats were exposed twice daily for 12 weeks to either the smoke generated from 30 cigarettes (smoke,exposed) or room air (sham,exposed). For the last five weeks of smoke exposure, the rats were fed Lieber-DeCarli liquid diets containing 0%, 16%, 26%, or 36% EtOH calories. The rats then were infected intranasally with S. pneumoniae, and movement of the organisms into the lower respiratory tract was quantified by plate counts of the tracheas and lungs 4 hr later. Ciliary beat frequency (CBF) analysis was performed on tracheal ring explants from each animal before and after stimulation with the ,-agonist isoproterenol, and tracheal epithelial cell protein kinase C (PKC) activity was measured. Results: Ingestion of any of the EtOH-containing diets resulted in a dose-dependent increase in movement of S. pneumoniae into the rats' lungs. This EtOH-induced defect was augmented further by concurrent smoke exposure, although smoke exposure alone had little effect on S. pneumoniae movement. Smoke, but not EtOH exposure, activated tracheal epithelial cell PKC. Increased movement of organisms into lungs correlated with a decrease in CBF and loss of the ciliary response to isoproterenol. Conclusion: EtOH ingestion in our model facilitated movement of S. pneumoniae into rats' lungs, a phenomenon exacerbated by concurrent smoke exposure. Furthermore, the organism's movement into the lungs correlated with a blunting of the rats' ciliary response to an established stimulus. Defects in mucociliary clearance thus may be one cause of the increased risk of pneumococcal infections in people who abuse alcohol, particularly if they also smoke. [source] Digital image analysis of the flagellar beat of activated and hyperactivated suncus spermatozoaMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 4 2007Takane Kaneko Abstract The flagellar beat of hyperactivated Suncus spermatozoa was analyzed by digital imaging and was compared to that of the nonhyperactivated (activated) spermatozoa in order to examine the function of the accessory fibers during the flagellar beat and the sliding filament mechanism inducing the motility of the hyperactivated spermatozoa. Unusual large and long characteristics of the accessory fibers were involved in generating the gently curved bends and a low beat frequency. Examination of the motility parameters of the flagellar beat of the activated and hyperactivated spermatozoa attached to a slide glass by their heads revealed that there were two beating modes: a frequency-curvature dependent mode in the activated flagellar beat and a nearly constant frequency mode in the hyperactivated flagellar beat. The hyperactivated flagellar beat was characterized by sharp bends in the proximal midpiece and a low beat frequency. The sharp bends in the proximal midpiece were induced by the increase in the total length of the microtubule sliding at the flagellar base. The rate of microtubule sliding (sliding velocity) in the axoneme remained almost constant in the flagellar beat of both the activated and hyperactivated spermatozoa. Comparison of the sliding velocity in Suncus, golden hamster, monkey, and sea urchin sperm flagella with their stiffness suggests that the sliding velocity is determined by the stiffness at the flagellar base and that the same sliding microtubule system functions in both mammalian and echinoderm spermatozoa. Mol. Reprod. Dev. 74: 478,485, 2007. © 2006 Wiley-Liss, Inc. [source] Influence of topical antifungal drugs on ciliary beat frequency of human nasal mucosa,THE LARYNGOSCOPE, Issue 7 2010An In Vitro Study Abstract Objectives/Hypothesis: Topical antifungal treatment is a subject of discussion in the treatment of chronic rhinosinusitis. The aim of this research was to study the effects of antifungal drugs on ciliary beat frequency (CBF) of human nasal mucosa under in vitro conditions. Study Design: Case series of in vitro experiments and in vitro study of cultured ciliated cells of human nasal mucosa. Methods: Human nasal mucosa was acquired during routine endoscopic sinus surgery. Cells were cultivated on object slides and exposed to different antifungal drugs in a newly developed test system. This system allowed continuous and reproducible exposure to different drugs at constant temperature, pH value, and osmolarity. The drugs were amphotericin B in two different concentrations and itraconazole. Results: Rinsing with higher concentrations of amphotericin B led to an immediate decrease of CBF, with a total stop after 15 minutes. A different result was seen in the group with lower concentrations; CBF decreased again quickly after rinsing with the test drug, but all of them recovered after rinsing with neutral solution. When using itraconazole a decline in CBF was observed again; one half of the samples returned to activity. Conclusions: Our in vitro results demonstrate a dose-dependent effect of the antifungal drugs amphotericin B and itraconazole on ciliary beat frequency of human nose epithelium. Laryngoscope, 2010 [source] Culture of nasal epithelial cells using chitosan-based membranesTHE LARYNGOSCOPE, Issue 10 2009Tsung-Wei Huang MD Abstract Objectives/Hypothesis: The aim of this study was to evaluate whether chitosan-based membranes can be used as scaffolds for growth and differentiation of nasal epithelial cells (NECs). Our final goal was to establish a novel methodology for enhancing the regeneration of the respiratory system. Study Design: Prospective study. Methods: Human NECs were cultured on three various substrates, e.g., chitosan membranes, collagen, and chitosan-collagen membranes. Morphology of NECs was examined via light and electron microscopy, the area of ciliated cells was measured by confocal microscopy, and ciliary beat frequency was also evaluated. Expression of mucin genes was investigated with reverse-transcription polymerase chain reaction. Results: NECs were found to be successfully adhesive with collagen and chitosan-collagen membranes at day 3 after seeding, but not with chitosan membranes. The cilia area on collagen were 6.1% ± 1.2%, 8.4% ± 1.4%, and 12.5% ± 1.9% at days 7, 14, and 21 after confluence, respectively, compared with 5.1% ± 0.9%, 8.6% ± 1.6%, and 12.3% ± 2.1% in chitosan-collagen membranes, exhibited nonsignificant difference (P > .05). There were no significant differences in ciliary beat frequency between each group. The expression levels of mucin genes, namely, MUC5AC, MUC5B, and MUC2, in NECs on both collagen and chitosan-collagen membranes did not differ significantly (P > .05). Conclusions: A small amount collagen mixed with chitosan substrate may improve the biocompatibility and promote the mucociliary differentiation in NECs. It appears that chitosan-collagen membrane is a promising scaffold for culture of the nasal epithelium, which sets the stage for studying tissue regeneration in the respiratory system. Laryngoscope, 2009 [source] Effects of ,-Toxin of Staphylococcus aureus on Ciliary Activity of Nasal Epithelial Cells ,THE LARYNGOSCOPE, Issue 12 2000Chung Seop Kim MD Abstract Objectives To investigate the in vitro effects of staphylococcal ,-to-in on ciliary activity and the in vivo effects on sinusitis induction. Study Design The in vitro effects of staphylococcal ,-to-in on ciliary activity were investigated at different concentrations and e-posure times. E-perimental sinusitis was induced in rabbits with application of ,-to-in and confirmed 7 days later. Methods Ciliated epithelial cells were taken from the ma-illary sinus mucosa of 10 rabbits. Five culture dishes from each rabbit were used for the e-perimental group, and one culture dish from each rabbit was used for the control group. In the experimental group, ciliary beat frequency (CBF) was measured at concentrations of 0.1, 1, 2, 5 and 10 U/mL of ,-toxin using a video-computerized analysis technique, while in the control group, culture medium containing no toxin was used. CBF was measured 1, 2, 4, 6, 8, 12, 24, and 48 hours after administration of ,-toxin. To induce experimental sinusitis, 2 U/mL of ,-toxin was percutaneously applied to the maxillary sinus of 10 rabbits without occlusion of the natural ostium, while normal saline was percutaneously applied to the right-side maxillary sinus of 4 rabbits in the control group. At 7 days, mucosal membranes were taken from the inferomedial wall of the maxillary sinus for light microscopic study. Results CBF dropped significantly after an 8-hour incubation at 2, 5, and 10 U/mL of ,-to-in. No ciliary activity was observed after a 24-hour incubation at 2 and 5 U/mL and a 12-hour incubation at 10 U/mL of ,-to-in. Mucoid, purulent discharge was observed in the ma-illary sinuses of the ,-to-in,applied group. Prominent epithelial disruption and infiltration of inflammatory cells into the epithelium and lamina propria were observed in the ,-to-in,applied group. Conclusions Staphylococcal ,-to-in may reduce ciliary activity and induce sinusitis without occlusion of the natural ostium of the ma-illary sinus in rabbits. This study provides another animal model of sinusitis for understanding the pathogenesis of sinusitis induced by bacterial e-oto-ins. [source] | ||||||||||||||||