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PubMed1990

Experiments on the use of DAMP to study retina and cultured neurons.

Immunocytochemical localization of DAMP, a reagent used to detect low pH intracellular compartments, was studied in cultured neurons from rat hippocampus and in frog retinas. We find that DAMP is more sharply localized and that the immunocytochemical reaction is stronger when horseradish peroxidase or other proteins are included in the medium used to administer DAMP to the cells. A likely explanation is that the proteins enter acidified endocytic compartments and there provide sites to which DAMP molecules can be attached during fixation.

Animals↗

PubMed1993

The effect of mechanical damping loads on disabling action tremor.

Patients with severe action tremor have uncontrollable, relatively rapid oscillatory motion super-imposed on otherwise useable slower voluntary motor activity. Because a mechanical damper produces an opposing force proportional to velocity, applying damping loads to tremorous limbs should attenuate the (high-velocity) tremor component of movement while permitting the slower purposeful portion to proceed relatively unopposed. In this study, the effect of upper extremity damping in three degrees of freedom was examined in 10 patients with cerebellar action tremor due to multiple sclerosis or traumatic brain injury. Variable amounts of damping were applied by prototype energy-dissipating orthoses which generated resistive viscous loads by means of computer-controlled magnetic particle brakes. All patients experienced statistically and functionally significant tremor reduction with the application of damping.

Adult↗

PubMedDate not supplied

Wheelchair caster shimmy II: damping.

The theory of shimmy damping is investigated including tire friction, spindle bearing friction, and hydraulic damping. A new theoretical improvement in hydraulic damping is presented. Experimental results are presented along with a discussion concerning the limitations due to the approximations used in the theory. The basic theory of wheelchair caster shimmy was published by the authors in 1984, and an examination of the sources of shimmy damping is corrected and updated in this paper.

Biomechanical Phenomena↗

PubMed2005

[Study on diagnostic standard for dampness syndrome in patients with chronic gastritis].

OBJECTIVE: To consummate the standard of macroscopic syndrome differentiation for diagnosis of dampness syndrome in patients with chronic gastritis (CG), based on the essentials of syndrome differentiation in TCM diagnostics and combined with the multivariant mathematical statistic method. And try to find out the methods and approaches for establishing standard for TCM syndrome differentiation. METHODS: Clinical investigation on CG patients was carried out adopting clinical epidemiological method. RESULTS: The meaningful symptoms for making diagnosis of Pi-Wei damp-heat syndrome in frequency order, were red tongue with yellow and greasy fur, sticky and greasy sensation in mouth, brown urine, constipation, dry stool, flushed face and ponderous extremities. Those for Pi deficiency with damp retention syndrome were swollen tongue with teeth-print, greasy fur, sticky and greasy sensation in mouth, tastelessness, and poor appetite. CONCLUSION: By combining the integrative medical theory with multivariant statistic method, the meaningful essentials for diagnosis of dampness syndrome can be screened out.

Adult↗

PubMed1978

Studies with a new antifolate 2,4-diamino-5-adamantyl-6-methylpyrimidine (DAMP): tissue distribution and disposition of 2,4-diamino-5-adamantyl-6-methylpyrimidine and its metabolite.

The pharmacokinetics of a potentially useful antitumor agent, 2,4-diamino-5-adamantyl-6-methylpyrimidine (DAMP) has been studied in rat using 14C-labeled drug. It is reported that DAMP is metabolized rapidly by liver microsomes to an unidentified compound. The metabolite seems to be excreted by liver more rapidly than the unchanged drug, and within 24 hours all radioactivity is eliminated, 80% through kidney and 20% through the bile. Both DAMP, and its metabolite accumulate readily in pancreas and kidney. In contrast, in the brain mostly unchanged DAMP could be detected. The accumulation of the drug in tissues other than liver is much greater after i.v. than after i.p. administration.

Adamantane↗

PubMed1994

Damp dusting in the operating theatre: implications for bacteria counts.

This paper describes a research study replicating and expanding on Pickering's paper on damp dusting and its effect on bacteria counts, which concluded that there had been little difference in the counts for both the damp dusting and non-damp dusting period. However there were unexplained fluctuations in levels of bacteria that the author could not explain. A recommendation of the study was to try to ascertain whether damp dusting alters airborne concentrations or whether it is a combination of other variables. This study hoped to explain this.

Air Microbiology↗

PubMed1998

Damp housing and asthma.

An allergic disposition has long been recognized as a risk factor for asthma. However, it has been suggested that, irrespective of genetic factors, exposure to environmental agents is of major importance in the development of asthma. In industrialized countries, people spend most of their time indoors and so environmental conditions inside the home may play an important role in asthma development. A review of studies examining the relationship between housing conditions and health in general or, more specifically, the relationship between respiratory symptoms/asthma and damp housing and mould has been carried out. These studies have shown that damp housing conditions are associated with increased prevalence of respiratory symptoms and asthma. The severity of asthma increases with an increasing quantity of dampness and mould in the home. It is suggested that damp conditions may, by a number of mechanisms, increase the allergenic burden so resulting in the development of asthma.

Adolescent↗

PubMed1998

FAIR excluding radiation damping (FAIRER).

It is shown that the flow-sensitive alternating inversion recovery (FAIR) technique is complicated by the effect of radiation damping, leading to problems in calibrating this method on phantoms and to inaccuracies in measured flows. A modified scheme called FAIRER (FAIR excluding radiation damping) is proposed, which suppresses the damping effects by employing very weak magnetic field gradients (0.06 G/cm) during the inversion recovery, spin-echo, and predelay periods. Results on phantoms and in vivo on cat brain are presented that demonstrate that FAIRER effectively solves these problems.

Animals↗

PubMed2001

Macroscopic background gradient and radiation damping effects on high-field PGSE NMR diffusion measurements.

The effects of macroscopic background gradients due to susceptibility differences at the sample interfaces and of radiation damping on pulsed-gradient spin-echo (PGSE) experiments are examined. Both phenomena can lead to the seemingly strange effect of the echo signal growing as the gradient strength increases at low applied gradient strengths. For a freely diffusing species, background gradients manifest themselves as slight concave or convex inflections in the linearized PGSE attenuation curve, depending on the polarity of the applied gradient. The various means of overcoming macroscopic background gradient problems, including bipolar gradients, and their efficacy are examined experimentally and discussed. The effects of radiation damping can also result in the attenuation curve being nonlinear but, different from the effect of background gradients, the nonlinearity does not change with the polarity of the applied gradient. The vulnerability of the stimulated echo-based PGSE sequence and variations of Hahn-based PGSE sequences is investigated. Both background gradients and radiation damping have serious implications for accurate diffusion measurement determination.

Journal Article↗

PubMed1995

Dampness and molds in day-care centers as an occupational health problem.

To assess the occurrence of respiratory and other symptoms among workers in relation to dampness in day-care centers, a random sample of 30 day-care centers in the city of Espoo, Finland, was selected for the study. The study population consisted of 268 female day-care workers, who filled in a questionnaire. Dampness was found to be common: water damage had taken place in 70% of the centers, and workers perceived mold odor in 17% of them. Adjusted risk of work-related eye and respiratory symptoms was in general higher among the day-care workers exposed to both water damage and mold odor than among the unexposed. The prevalence of eye symptoms was statistically significantly higher. The results provide new evidence of the importance of dampness and mold problems in the work environment as determinants of respiratory and irritative symptoms.

Adolescent↗

PubMed1988

Parameters of exponentially damped sinusoids in noise and their application to the analysis of visual evoked potentials.

The backward prediction and singular value (SV) truncation methods for estimating multiple exponentially damped real sinusoids in noise have been studied. The basic theory and algorithm are outlined, and the effect on the error of computational parameters, such as the sampling window, the sampling rate, the order of the prediction-error filter (PEF) and the truncated point of SV, were studied using simulated data. If the computational parameters are carefully chosen, the estimate of frequency and damping factor of a damped sinusoid is quite accurate (within a certain range of signal to noise (S/N) ratio). We use this method to estimate the parameters of visual evoked potentials (VEP) and then reconstructed them from estimated parameters according to the resonant model. The error between original VEP and the reconstructed waveform is within 5%. This method can be used in the analysis and recognition of various systems.

Algorithms↗

PubMed1994

Rodent biodistribution and metabolism of tritiated 4-DAMP, a M3 subtype-selective cholinoceptor ligand.

The biodistribution of [3H]4-DAMP (a M3-selective cholinoceptor antagonist) was studied in rats which had received either saline or saline containing atropine (to block cholinoceptors). Specific binding of the radioligand was observed in the urinary bladder, ileum, pancreas, stomach, submandibular gland and trachea. Maximal ratios of total-to-non-specific uptake reached values of 1.8 (trachea), 3.2 (bladder), 4.0 (stomach), 4.8 (ileum), 6.6 (pancreas) and 6.9 (submandibular gland) at 5-10 min post-injection; this rank order reflects the tissue densities of M3 cholinoceptors, 4-DAMP did not bind to blood cells and it was rapidly cleared from the circulation (> 90% with a half-life of 0.2 min, the remainder with a half-life of 9.4 min). Labelled metabolites appeared within 5 min in plasma, but metabolite uptake by the target organs was low (< 15% of total radioactivity 40 min post-injection). Although 4-DAMP binds to M3-cholinoceptors in vivo, its potential use as a radiopharmaceutical appears limited since the compound does not cross the blood-brain barrier and it does not show measurable specific binding in airways.

Animals↗

PubMed2003

Enhanced mass resolution tandem mass spectrometry method for 2,3,7,8-tetrachlorodibenzo-p-dioxin detection with ion trap mass spectrometry using high damping gas pressure.

Damping gas flow was optimized for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) determination using ion trap mass spectrometer. A tandem mass spectrometry (MS-MS) method with better than unit-mass resolution (mass width, 0.3 u) was developed at a damping gas flow of 1.5 ml/min and a collision-induced dissociation (CID) voltage of 3.30 V. The relative standard deviation (R.S.D.) at the enhanced resolution was 2.9% in 24 h of consecutive injections. The detection limit was significantly improved because the efficiency of both precursor ion trapping and fragmentation increased with the damping gas flow. Product ion yield was 4.5 times higher and limit of detection was 3.2 times lower than at the default flow (0.3 ml/min and 1.65 V).

Mass Spectrometry↗

PubMed2004

The damping properties of the venous plexus of the heel region of the foot during simulated heelstrike.

The damping mechanisms that are operational in the heel pad during the impact phase of locomotion have the important function to protect the musculo-skeletal system from injuries. How this is achieved is still not fully understood, as is for instance illustrated by the 'heel pad paradox', the observation that in vivo and in vitro experiments yielded widely different results. This paradox could so far only partially be explained. In the light of this paradox, and a previous study by our group, we conjectured that the venous plexus might contribute as a hydraulic shock absorber to the damping properties of the heel pad. To investigate this hypothesis in vivo, heel pads of 11 volunteers were subjected to pendulum impact tests, using velocities of 0.2, 0.4, and 0.6 m/s, and three physiologically different, consecutive conditions: (i) a relatively empty venous plexus, (ii) a congested venous plexus, and (iii) a decongested venous plexus. At congestion, the maximum impact force decreased slightly but significantly by 2.6% at 0.2 m/s and 1.8% at 0.4 m/s. This effect was no longer found at 0.6 m/s. Although these effects are rather small, they confirm the fundamental hypothesis that the venous plexus contributes to the damping properties of the heel pad during walking. It is likely that some underestimation of the effect has occurred.

Acceleration↗

PubMed2006

Task-specific recruitment of motor units for vibration damping.

Vibrations occur within the soft tissues of the lower extremities due to the heel-strike impact during walking. Increases in muscle activity in the lower extremities result in increased damping to reduce this vibration. The myoelectric intensity spectra were compared using principal component analysis from the tibialis anterior and lateral gastrocnemius of 40 subjects walking with different shoe conditions. The soft insert condition resulted in a significant, simultaneous increase in muscle activity with a shift to higher myoelectric frequencies in the period 0-60 ms after heel-strike which is the period when the greater vibration damping occurred. These increases in myoelectric frequency match the spectral patterns which indicate increases in recruitment of faster motor units. It is concluded that fast motor units are recruited during the task of damping the soft-tissue resonance that occurs following heel-strike.

Computer Simulation↗

PubMed2006

Temperature dependence of the damping constant and the order parameter close to the lambda phase transitions in ammonium halides.

This study gives our calculation for the damping constant, using the expressions derived for an Ising pseudospin-phonon coupled system in the ammonium halides (NH(4)Cl and NH(4)Br). For this calculation of the damping constant, we use the temperature dependence of the order parameter calculated from the molecular field theory. We predict here the damping constants for the v(5) (174 cm(-1)) and v(5) (177 cm(-1)) Raman modes of NH(4)Cl and NH(4)Br, respectively, below T(lambda) and compare them with our observed bandwidths measured as a function of temperature for those phonon modes at zero pressure. Our predictions agree well with the observed bandwidths below T(lambda) for those modes in both ammonium halide structures, in particular for NH(4)Br. Some discrepancy that occurs below T(lambda) for the v(5) (174 cm(-1)) mode of NH(4)Cl, is explained in terms of the model studied here.

Algorithms↗

PubMed2000

DNA typing of human remains found in damp environments.

DNA typing is often used to determine identity from human remains. The environment to which the material has been exposed, however, is crucial for the success of the investigation. Damp conditions in particular can cause a rapid degradation of DNA, even in bone and teeth, and thus reduce the chances of successful typing. Here, we present the results of investigations performed on four skulls that had been lying in a damp environment for periods ranging from almost 1 year to about 45 years. In none of these cases was DNA typing successful on bone or, where present, on teeth. Where remnants of brain tissue were used, however, complete STR typing was possible in one case, partial STR typing in another, and mtDNA sequencing could be carried out in three cases. These findings suggest that brain tissue is relatively resistant to putrefaction in damp environments and, unlike bone, appears to exhibit a certain degree of protection against DNA degradation.

Aged↗

PubMed1999

Comparison of a novel rectilinear biphasic waveform with a damped sine wave monophasic waveform for transthoracic ventricular defibrillation. ZOLL Investigators.

OBJECTIVES: We compared the efficacy of a novel rectilinear biphasic waveform, consisting of a constant current first phase, with a damped sine wave monophasic waveform during transthoracic defibrillation. BACKGROUND: Multiple studies have shown that for endocardial defibrillation, biphasic waveforms have a greater efficacy than monophasic waveforms. More recently, a 130-J truncated exponential biphasic waveform was shown to have equivalent efficacy to a 200-J damped sine wave monophasic waveform for transthoracic ventricular defibrillation. However, the optimal type of biphasic waveform is unknown. METHODS: In this prospective, randomized, multicenter trial, 184 patients who underwent ventricular defibrillation were randomized to receive a 200-J damped sine wave monophasic or 120-J rectilinear biphasic shock. RESULTS: First-shock efficacy of the biphasic waveform was significantly greater than that of the monophasic waveform (99% vs. 93%, p = 0.05) and was achieved with nearly 60% less delivered current (14 +/- 1 vs. 33 +/- 7 A, p < 0.0001). Although the efficacy of the biphasic and monophasic waveforms was comparable in patients with an impedance < 70 ohms (100% [biphasic] vs. 95% [monophasic], p = NS), the biphasic waveform was significantly more effective in patients with an impedance > or = 70 ohms (99% [biphasic] vs. 86% [monophasic], p = 0.02). CONCLUSIONS: This study demonstrates a superior efficacy of rectilinear biphasic shocks as compared with monophasic shocks for transthoracic ventricular defibrillation, particularly in patients with a high transthoracic impedance. More important, biphasic shocks defibrillated with nearly 60% less current. The combination of increased efficacy and decreased current requirements suggests that biphasic shocks as compared with monophasic shocks are advantageous for transthoracic ventricular defibrillation.

Aged↗