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PubMed1979

A data analysis microcomputer package (DAMP) for biomedical signals.

The advent of cheap, powerful microcomputer systems makes the analysis of data via sophisticated techniques available to the personnel who are non-specialists in computing systems. The DAMP package described here is intended for use on personal computers and has therefore been written in BASIC for portability. The analysis techniques are powerful, comprising algorithms to perform sample-data generation, plotting displays, digital data filtering, auto-correlation functions, fast Fourier transforms and autoregressive modelling. The last technique contains a number of options including the display of z-plane plots, frequency response of the model, residual plotting and auto-correlation of the residuals. Illustrative results are shown from psychological mood data and rat locomotor activity. The package is designed both to instruct a user in the techniques of spectral analysis, and also to provide a range of methods for investigating time and frequency behaviour of biomedical data.

Biomedical Engineering↗

PubMed1991

Radial coherence, wave velocity and damping of electrocortical waves.

Mean squared coherence was calculated as a function of frequency (1-32 Hz) and electrode separation (1-8 mm) from 64-channel extradural arrays on occipito-parietal association cortex of cats. A 2-parameter theoretical function was then fitted to sets of pooled estimates. The theoretical function described coherences between recording sites of small separation for linear, non-dispersive, dissipative waves moving on an infinite homogeneous plane medium, and driven by spatio-temporally noisy inputs. Residuals of fit were then plotted as a function of frequency and distance, and were found to show no systematic trends with frequency, but an irregular and generally increasing relation to distance. This was the result predicted for linear non-dispersive waves on a surface actually folded, and with significant additional wave action generated between electrodes. Further recordings of coherence from more widely separated electrodes indicated that boundary conditions were absorbing or remote, rather than closed or reentrant. The phase velocity for electrocortical waves obtained from autoregression estimates of temporal damping and parameters of fit to coherence, was found in the range 0.1-0.29 m/sec, and appeared independent of the direction of electrode alignment. This compares with the velocity of 0.33 m/sec for alpha waves earlier found by Lopes da Silva and Storm van Leeuwen.

Animals↗

PubMed1986

Uncharged tRNA error damping model.

Uncharged tRNA is known to bind to the ribosome in a codon-specific fashion. In this way, cognate uncharged tRNA competes with non-cognate aminoacyl-tRNA. If uncharged tRNA can be aminoacylated while on the ribosome, this will damp errors due to aminoacyl-tRNA imbalance. Kinetic analysis shows that this scheme reduces errors at 'hungry' codons considerably more effectively than J. Ninio's accuracy tuner model; for example, a 10-fold decrease in cognate aminoacyl-tRNA elicits only a 10% increase in the error frequency.

Binding, Competitive↗

PubMed1991

Inhibition of the morphine withdrawal syndrome by a novel muscarinic antagonist (4-DAMP).

It has been recognized for many years that central cholinergic neurons are susceptible to inhibition by opiates and that during withdrawal their firing rates are enhanced. Nevertheless, classical nonselective muscarinic receptor antagonists have not been demonstrated to provide consistent inhibition of withdrawal symptoms in humans or in animal models. The purpose of this study was to determine whether selective blockade of central M1 or M2 muscarinic receptor subtypes could provide inhibition of naloxone precipitated withdrawal symptoms in morphine dependent rats. As with earlier human studies, both cardiovascular and behavioral measures of withdrawal were quantitated. The selective M2 receptor antagonist 4-DAMP was significantly more effective than the M1 antagonist pirenzepine in reducing both cardiovascular and behavioral symptoms. These results are consistent with a role for cholinergic neurons in the expression of certain morphine withdrawal symptoms and suggest that future therapies might be targeted towards central M2 receptors.

Animals↗

PubMed1987

Population biology of hookworms in west Bengal: analysis of numbers of infective larvae recovered from damp pads applied to the soil surface at defaecation sites.

The aims of this study were to analyze the seasonal distribution of infective larvae on the soil surface, to determine whether numbers of infective larvae near faeces were related to the faecal egg count of individuals, and to relate the distribution of larvae to environmental characteristics. Larvae were recovered from damp pads, applied to the soil surface in an annulus around fresh, identified stools of individuals who were participating in a larger epidemiological study. This provided an estimate of exposure to infection at the time of defaecation. Transmission was restricted to the rainy season and large aggregations of larvae were encountered earlier rather than later in the rainy season. Frequency distributions for the number of larvae extracted from each pad showed a high degree of aggregation, with most monthly counts showing good fits to the negative binomial probability distribution. Despite variations in monthly sampling means, the degree of aggregation in the population of larvae was remarkably stable over the 18 month sampling period (k of negative binomial = 0.01 to 0.08). Estimates of the degree of aggregation of the parasites in the human population were also available, and comparisons suggest that the infective larvae were much more aggregated than the parasitic stages. There was no relationship between the mean daily egg output of individuals and the number of larvae which developed and were recovered from the soil surface near the faeces. Thus, people who contribute large numbers of eggs to the environment are not necessarily those who are the greatest source of infection for others.(ABSTRACT TRUNCATED AT 250 WORDS)

Ancylostoma↗

PubMed1995

Auditory air and bone conduction brainstem responses and damped rotation test for young children with bilateral congenital atresia of the ears.

This paper describes our assessment of auditory and vestibular functions at a very early age using the auditory air and bone conduction brainstem responses and the damped rotation test for infants and children with bilateral congenital atresia of the ear. Twelve infants and children with congenital microtia and occlusion of bilateral auditory canals were evaluated by this assessment to determine their function of hearing and balance and their suitability for fitting and surgical improvement.

Audiometry, Evoked Response↗

PubMed1995

Damped oscillatory activity in the guinea pig accessory olfactory bulb slice.

Extracellular field potentials were recorded from guinea pig accessory olfactory bulb (AOB) slices following electrical stimulation of the vomeronasal nerve layer (VNL). A single shock of the VNL provoked a characteristic damped oscillatory field potential, which consisted of a compound action potential followed by 6-7 periodic negative peaks (n1, n2, n3, n4, n5, n6 or n7). The average frequency of the oscillation was 32 Hz. The existence of oscillation in the AOB suggests the possibility that the oscillatory activity not only may reflect 'quantal' sampling periods, but also may be dynamically altering the AOB conditions under which incoming pheromone-like information is processed.

Action Potentials↗

PubMed1995

Synthesis, muscarinic blocking activity and molecular modeling studies of 4-DAMP-related compounds.

A number of compounds structurally related to 4-DAMP (1) were synthesized and a single crystal X-ray structural study on a representative member of this series was carried out. All the compounds were tested for the antagonist activity in isolated guinea pig atria (M2 muscarinic receptors) and ileum (M3 muscarinic receptors). Affinity values (pA2) for the muscarinic receptor subtypes ranged from 5.39 to 9.71 (M2) and from 5.68 to 9.92 (M3), depending on different structural features of the compounds. A molecular modeling study was performed, with the aim of rationalizing the affinity data for both M2 and M3 muscarinic receptor subtypes. The presence in the series of two highly active, structurally constrained derivatives allowed us to define two different pharmacophoric frames on which all the compounds could be fitted in a satisfactory manner.

Animals↗

PubMed2004

Comparison of the rectilinear biphasic waveform with the monophasic damped sine waveform for external cardioversion of atrial fibrillation and flutter.

External cardioversion using the monophasic damped sine (MDS) waveform is successful 70% to 94% of the time when using up to 360 J. The rectilinear biphasic (RLB) defibrillator has been shown to be superior in efficacy to the MDS waveform in atrial cardioversion in a small randomized study. This larger, retrospective study compares the results of the RLB waveform with those of the MDS waveform for cardioversion of atrial fibrillation (AF) and atrial flutter in a large cohort of patients. We performed 1,877 external cardioversion procedures in 1,361 patients for AF and atrial flutter by using the RLB defibrillator. We compared these results with those of the MDS defibrillator in 2,025 patients who underwent 2,818 cardioversion procedures. The overall success rates for the RLB defibrillator were 99.1% for AF and 99.2% for atrial flutter, and the corresponding success rates for the MDS defibrillator were 92.4% and 99.8% (p <0.001; RLB superior for AF). The median overall successful energy level for the MDS waveform was 200 J, whereas the corresponding RLB energy level was 100 J. Multivariate analyses demonstrated that underlying clinical conditions or use of antiarrhythmic drugs does not significantly affect overall success rates. Our results from >4,000 procedures confirmed and extended those of the previous report by showing a very high success rate for cardioversion of AF and atrial flutter using the RLB waveform. The MDS waveform was equally effective for atrial flutter but significantly less effective in terminating AF.

Aged↗

PubMed2005

Systems-level dissection of the cell-cycle oscillator: bypassing positive feedback produces damped oscillations.

The cell-cycle oscillator includes an essential negative-feedback loop: Cdc2 activates the anaphase-promoting complex (APC), which leads to cyclin destruction and Cdc2 inactivation. Under some circumstances, a negative-feedback loop is sufficient to generate sustained oscillations. However, the Cdc2/APC system also includes positive-feedback loops, whose functional importance we now assess. We show that short-circuiting positive feedback makes the oscillations in Cdc2 activity faster, less temporally abrupt, and damped. This compromises the activation of cyclin destruction and interferes with mitotic exit and DNA replication. This work demonstrates a systems-level role for positive-feedback loops in the embryonic cell cycle and provides an example of how oscillations can emerge out of combinations of subcircuits whose individual behaviors are not oscillatory. This work also underscores the fundamental similarity of cell-cycle oscillations in embryos to repetitive action potentials in pacemaker neurons, with both systems relying on a combination of negative and positive-feedback loops.

Anaphase-Promoting Complex-Cyclosome↗

PubMed2004

Complexes of dichloro[2-(dimethylaminomethyl)phenyl-C1,N]gold(III), [Au(damp-C1,N)Cl2], with formylferrocene thiosemicarbazones: synthesis, structure and cytotoxicity.

Dichloro[2-(dimethylaminomethyl)phenyl- phenyl-C1,N]gold(III), [Au(damp-C1,N)Cl2], reacts with the formylferrocene thiosemicarbazones derived from 4-methyl-, 4-phenyl-, 4-ethyl- and 4,4-dimethyl-3-thiosemicarbazides, HFcTSC, to give complexes of general formula [Au(Hdamp-1C)Cl(FcTSC)]Cl. These complexes were isolated and characterized by elemental analysis, mass spectrometry and IR, 1H NMR and (13)C NMR spectroscopy. In some cases, cyclic voltammetric studies were carried out and these showed that the complexation of gold affects the redox behaviour of the ferrocene unit. The in vitro antitumor activity against the HeLa cell line was also determined for the more soluble complexes. The IC(50) values were found to be higher than that of cisplatin but the maximum antiproliferative activity was similar.

Antineoplastic Agents↗

PubMed2019

Increased acetylation of H3K14 in the genomic regions that encode trained immunity enzymes in lysophosphatidylcholine-activated human aortic endothelial cells - Novel qualification markers for chronic disease risk factors and conditional DAMPs.

To test our hypothesis that proatherogenic lysophosphatidylcholine (LPC) upregulates trained immunity pathways (TIPs) in human aortic endothelial cells (HAECs), we conducted an intensive analyses on our RNA-Seq data and histone 3 lysine 14 acetylation (H3K14ac)-CHIP-Seq data, both performed on HAEC treated with LPC. Our analysis revealed that: 1) LPC induces upregulation of three TIPs including glycolysis enzymes (GE), mevalonate enzymes (ME), and acetyl-CoA generating enzymes (ACE); 2) LPC induces upregulation of 29% of 31 histone acetyltransferases, three of which acetylate H3K14; 3) LPC induces H3K14 acetylation (H3K14ac) in the genomic DNA that encodes LPC-induced TIP genes (79%) in comparison to that of in LPC-induced effector genes (43%) including ICAM-1; 4) TIP pathways are significantly different from that of EC activation effectors including adhesion molecule ICAM-1; 5) reactive oxygen species generating enzyme NOX2 deficiency decreases, but antioxidant transcription factor Nrf2 deficiency increases, the expressions of a few TIP genes and EC activation effector genes; and 6) LPC induced TIP genes(81%) favor inter-chromosomal long-range interactions (CLRI, trans-chromatin interaction) while LPC induced effector genes (65%) favor intra-chromosomal CLRIs (cis-chromatin interaction). Our findings demonstrated that proatherogenic lipids upregulate TIPs in HAECs, which are a new category of qualification markers for chronic disease risk factors and conditional DAMPs and potential mechanisms for acute inflammation transition to chronic ones. These novel insights may lead to identifications of new cardiovascular risk factors in upregulating TIPs in cardiovascular cells and novel therapeutic targets for the treatment of metabolic cardiovascular diseases, inflammation, and cancers. (total words: 245).

Acetylation↗

PubMed2005

Out-of-hospital cardiac arrest rectilinear biphasic to monophasic damped sine defibrillation waveforms with advanced life support intervention trial (ORBIT).

BACKGROUND: Although biphasic defibrillation waveforms appear to be superior to monophasic waveforms in terminating VF, their relative benefits in out-of-hospital resuscitation are incompletely understood. Prior comparisons of defibrillation waveform efficacy in out-of-hospital cardiac arrest (OHCA) are confined to patients presenting in a shockable rhythm and resuscitated by first responder (basic life support). This effectiveness study compared monophasic and biphasic defibrillation waveform for conversion of ventricular arrhythmias in all OHCA treated with advance life support (ALS). METHODS AND RESULTS: This prospective randomized controlled trial compared the rectilinear biphasic (RLB) waveform with the monophasic damped sine (MDS) waveform, using step-up energy levels. The study enrolled OHCA patients requiring at least one shock delivered by ALS providers, regardless of initial presenting rhythm. Shock success was defined as conversion at 5s to organized rhythm after one to three escalating shocks. We report efficacy results for the cohort of patients treated by ALS paramedics who presented with an initially shockable rhythm who had not received a shock from a first responder (MDS: n=83; RLB: n=86). Shock success within the first three ascending energy shocks for RLB (120, 150, 200J) was superior to MDS (200, 300, 360J) for patients initially presenting in a shockable rhythm (52% versus 34%, p=0.01). First shock conversion was 23% and12%, for RLB and MDS, respectively (p=0.07). There were no significant differences in return of spontaneous circulation (47% versus 47%), survival to 24h (31% versus 27%), and survival to discharge (9% versus 7%). Mean 24h survival rates of bystander witnessed events showed differences between waveforms in the early circulatory phase at 4-10 min post event (mean (S.D.) RLB 0.45 (0.07) versus MDS 0.31 (0.06), p=0.0002) and demonstrated decline as time to first shock increased to 20 min. CONCLUSION: Shock success to an organized rhythm comparing step-up protocol for energy settings demonstrated the RLB waveform was superior to MDS in ALS treatment of OHCA. Survival rates for both waveforms are consistent with current theories on the circulatory and metabolic phases of out-of-hospital cardiac arrest.

Adult↗

PubMed2006

A randomized controlled trial of efficacy and ST change following use of the Welch-Allyn MRL PIC biphasic waveform versus damped sine monophasic waveform for external DC cardioversion.

OBJECTIVE: Biphasic waveforms have similar or greater efficacy at cardioverting atrial and ventricular arrhythmias at lower energy levels than monophasic waveforms, and cause less ST depression following defibrillation of ventricular fibrillation. No studies have investigated this effect on ST change with atrial arrhythmias. We studied the efficacy of the Welch Allyn-MRL PIC biphasic defibrillator. METHODS: One hundred and thirty-nine patients undergoing elective DC cardioversion for atrial arrhythmias were randomised to cardioversion by monophasic (Hewlett Packard Codemaster XL; 100, 200, 300, 360 and 360J) or biphasic (Welch Allyn-MRL PIC; 70, 100, 150, 200 and 300J) defibrillator. We analysed success of cardioversion after 0 and 30min, cumulative energy, number of shocks and energy at successful cardioversion. The ST change in the recorded electrocardiogram was measured at 15s after all shocks using electronic callipers. RESULTS: Immediately after cardioversion 59/68 (86.8%) of the monophasic group versus 56/60 (93.3%) of the biphasic group were in sinus rhythm. Of the monophasic group, 55/67 (82.1%) remained in sinus rhythm at 30min versus 53/58 (91.4%) of the biphasic group. These differences were not significant at 0min (P=0.35) or 30min (P=0.21). The biphasic group required significantly fewer shocks (P=0.006), less cumulative energy (P<0.0001) and required lower total energy for successful cardioversion (P<0.0001). Of the 102 patients with electrocardiogram recordings suitable for analysis, ST segment change was greater in the monophasic group (P=0.037). CONCLUSIONS: The Welch Allyn-MRL biphasic waveform for DC cardioversion results in fewer shocks, with less cumulative energy delivered and less post shock ST change than with a Hewlett Packard Codemaster XL damped sine wave monophasic waveform.

Adult↗

PubMed2006

Energy dissipation and frequency shift of a damped dynamic force microscopy.

The closed-form solution of the transient response of damped dynamic force microscopy subjected to the nonlinear interatomic force is derived. The frequency shift and the decay rate of a V-typed probe can be determined easily and precisely by the proposed method. If the taper ratio is zero, a uniform cantilever is obtained. Moreover, the transient response of a non-uniform cantilever can be determined also in the same way. The complex Young's modulus is used to describe the viscoelastic material property. In the modulus, the loss factor is introduced. The relation between the Q-factor and the loss factor is discussed. Moreover, the relation between the energy dissipation and the frequency shift is revealed. Finally, the effects of several parameters on the Q-factor, the frequency shift and the decay rate are investigated. The proposed method can be easily applied to investigate the tapping mode of AFM.

Journal Article↗

PubMed1979

The undamped and damped series elastic components of a vascular smooth muscle.

Small arterial resistance vessels (internal diameter about 175 micrometer) have been mounted on a myograph that enabled their wall tension, T, and internal circumference, L, to be measured and controlled with a time resolution of about 4 ms. Maximally activated vessels were subjected to isometric releases (step changes in L) and isotonic releases (step changes in T) of varying extents and at two different temperatures (27 degree C and 37 degree C). The recovery from an isometric release was monotonic and did not include the two phases seen in skeletal muscles. The isotonic release response did, however, contain a velocity transient lasting about 150 ms: the velocity immediately after the release was about six times the steady shortening velocity. The form of both the isometric and isotonic release responses and their dependence on the extent of release can be explained in terms of a modified Hill model in which the "series elastic component" (SEC) is replaced by the series combination of an undamped-SED (that is, an undamped elastic element) and a damped-SEC (a Voigt element). Although the initial response to both types of release was independent of temperature, all stages of subsequent responses were temperature dependent, with Q10's in the range 1.5 - 2.0. The results suggest that the responses to isotonic and isometric releases may in part be due to active processes.

Animals↗

PubMed2003

Noninvasive measurement of viscosity from damping of capillary waves.

Capillary waves are surface waves on fluids with wavelengths in the millimeter range. The determination of viscosity from the damping of capillary waves is of great practical importance as it affords the possibility of measuring the viscosity of fluids noninvasively. In this paper a noncontact method for generation and detection of capillary waves on fluid is described. A miniature laser interferometer is employed to measure noninvasively the wave amplitude and its attenuation with a resolution of about 10 nm. As a test case, the attenuation data for capillary waves on pure water are used to obtain the kinematic viscosity of water as a function of temperature. The results compare favorably with the most reliable published data on the subject.

Capillary Action↗

PubMed1999

The effect of muscle stiffness and damping on simulated impact force peaks during running.

It has been frequently reported that vertical impact force peaks during running change only minimally when changing the midsole hardness of running shoes. However, the underlying mechanism for these experimental observations is not well understood. An athlete has various possibilities to influence external and internal forces during ground contact (e.g. landing velocity, geometrical alignment, muscle tuning, etc.). The purpose of this study was to discuss one possible strategy to influence external impact forces acting on the athlete's body during running, the strategy to change muscle activity (muscle tuning). The human body was modeled as a simplified mass-spring-damper system. The model included masses of the upper and the lower bodies with each part of the body represented by a rigid and a non-rigid wobbling mass. The influence of mechanical properties of the human body on the vertical impact force peak was examined by varying the spring constants and damping coefficients of the spring-damper units that connected the various masses. Two types of shoe soles were modeled using a non-linear force deformation model with two sets of parameters based on the force-deformation curves of pendulum impact experiments. The simulated results showed that the regulation of the mechanical coupling of rigid and wobbling masses of the human body had an influence on the magnitude of the vertical impact force, but not on its loading rate. It was possible to produce the same impact force peaks altering specific mechanical properties of the system for a soft and a hard shoe sole. This regulation can be achieved through changes of joint angles, changes in joint angular velocities and/or changes in muscle activation levels in the lower extremity. Therefore, it has been concluded that changes in muscle activity (muscle tuning) can be used as a possible strategy to affect vertical impact force peaks during running.

Elasticity↗