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PubMed1996

ADHD, DAMP and other neurodevelopmental/psychiatric disorders in 6-year-old children: epidemiology and co-morbidity.

A total population of 589 6-year-old children were screened for neurodevelopmental/neuropsychiatric disorders by questionnaires to parents and preschool teachers, and by examination of motor abilities at the Child Health Center. Fifty screen-positive and fifty screen-negative children were assigned for complete neuropsychiatric assessment comprising a detailed history, psychiatric and neurodevelopmental assessment, neuropsychological examination and speech/language evaluation. Comprehensive diagnoses were made on the basis of all the available information. In the total population, 63 children (10.7%) with disorders were identified, 10 of whom had a diagnosis established before the study. The prevalence rates for deficits in attention, motor control and perception (DAMP) were 5.3 to 6.9%, for attention deficit hyperactivity disorder (ADHD) they were 2.4 to 4.0% and for mental retardation, 2.5%. Co-morbidity was established for ADHD on the one hand and DAMP, mental retardation and Tourette syndrome on the other. The findings suggest the need for a school entrant screening examination for the types of problems examined in this study.

Attention Deficit Disorder with Hyperactivity↗

PubMed1989

The X-ray crystal structure of 4-diphenylcarbamyl-N-methyl-piperidine methobromide (the carbamate analogue of 4-DAMP methiodide).

1. Crystals of 4-diphenylcarbamyl-N-methylpiperidine methobromide contain 2 conformers, one with the ester group equatorial and the other with the ester group axial to the piperidine ring. 2. In both conformers and diphenylcarbamyl nitrogen is trigonally substituted and flat compared with the tetrahedral substitution of the corresponding carbon atom in 4-diphenylacetoxy-N-methylpiperidine (4-DAMP) methiodide. 3. The low activity and selectivity of the carbamate at muscarinic receptors is comparable with that of compounds containing only one phenyl ring, e.g. phenylacetyl-N-methyl piperidine methiodide or phenylacetylcholine. It is suggested that the high affinity of 4-DAMP metho-salts and their selectivity depend upon interactions with groups arranged in three dimensions and that the trigonal arrangement about the nitrogen atom in the carbamate makes it impossible for both benzene rings to interact at once.

Crystallization↗

PubMed1990

4-DAMP analogues reveal heterogeneity of M1 muscarinic receptors.

The muscarinic receptors responsible for two effects elicited by McN-A-343, i.e. the relaxation of the rat duodenum and the inhibition of the twitch contraction of rabbit vas deferens, were investigated by use of derivatives of 4-diphenyl acetoxy-N-methyl piperidine methobromide (4-DAMP). Both receptors had been previously identified as M1 on the basis of the high affinity shown towards pirenzepine. Schild analysis of antagonism revealed that the affinities of 4-DAMP and three of its analogues in the rat duodenum were significantly different from those estimated in rabbit vas deferens. These data indicate that distinct receptor subtypes mediate duodenal relaxation and vas deferens inhibition of twitch contraction and suggest that receptors classified as M1 by means of pirenzepine affinity constitute a heterogeneous population.

(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethy↗

PubMed1991

The use of 4-diphenylacetoxy-N-(2-chloroethyl)-piperidine (4-DAMP mustard) for estimating the apparent affinities of some agonists acting at muscarinic receptors in guinea-pig ileum.

1. 4-Diphenylacetoxy-N-(2-chloroethyl)-piperidine (4-DAMP mustard), which is known to block muscarinic M3 receptors in preference to muscarinic M2 receptors, was used to estimate the apparent affinity constants of some agonists acting at muscarinic receptors in guinea-pig ileum. Estimates for carbachol and n-pentyl-trimethyl ammonium iodide were similar to published values obtained in similar conditions: those for n-hexyl-trimethyl ammonium iodide were slightly lower. 2. The results for the agonists, n-pentyl- and n-hexyl-trimethyl ammonium iodides and for the partial agonist, n-heptyl-trimethyl ammonium iodide were not as regular as was suggested by Stephenson, though there is an overall increase in apparent affinity with chain length. 3. Estimates of apparent affinity may be affected by hexamethonium, usually present in experiments on ileum. Its absence had little effect on the results with carbachol but reduced the estimates obtained with n-pentyl trimethyl ammonium, which has strong nicotinic effects compared with its muscarinic effects. On ileum treated with tetrodotoxin the values for n-pentyl trimethyl ammonium were similar to those obtained in the presence of hexamethonium (0.28 mM): slightly higher estimates of affinity were obtained in the presence of indomethacin (2.8 microM). The nicotinic effects of n-pentyl ammonium may involve the release of prostaglandins. 4. The estimates of apparent affinity did not depend on the method used to calculate them as the 'null' method and the 'operational' method give similar answers. Estimates of the transducer-ratio for the partial agonist, n-heptyl-trimethyl ammonium iodide, were numerically the same as those of its efficacy. 5. This work illustrates the use of 4-DAMP mustard as a tool for measuring the apparent affinity of agonists acting at muscarinic M3 receptors.

Animals↗

PubMed2004

Building-related respiratory symptoms can be predicted with semi-quantitative indices of exposure to dampness and mold.

UNLABELLED: Using a semi-quantitative mold exposure index, the National Institute for Occupational Safety and Health (NIOSH) investigated 13 college buildings to examine whether building-related respiratory symptoms among employees are associated with environmental exposure to mold and dampness in buildings. We collected data on upper and lower respiratory symptoms and their building-relatedness, and time spent in specific rooms with a self-administered questionnaires. Trained NIOSH industrial hygienists classified rooms for water stains, visible mold, mold odor, and moisture using semi-quantitative scales and then estimated individual exposure indices weighted by the time spent in specific rooms. The semi-quantitative exposure indices significantly predicted building-related respiratory symptoms, including wheeze [odds ratio (OR) = 2.3; 95% confidence interval (CI) = 1.1-4.5], chest tightness (OR = 2.2; 95% CI = 1.1-4.6), shortness of breath (OR = 2.7; 95% CI = 1.2-6.1), nasal (OR = 2.5; 95% CI = 1.3-4.7) and sinus (OR = 2.2; 95% CI = 1.2-4.1) symptoms, with exposure-response relationships. We found that conditions suggestive of indoor mold exposure at work were associated with building-related respiratory symptoms. Our findings suggest that observational semi-quantitative indices of exposure to dampness and mold can support action to prevent building-related respiratory diseases. PRACTICAL IMPLICATIONS: Current air sampling methods have major limitations in assessing exposure to mold and other biological agents that may prevent the demonstration of associations of bioaerosol exposure with health. Our study demonstrates that semi-quantitative dampness/mold exposure indices, based solely on visual and olfactory observation and weighted by time spent in specific rooms, can predict existence of excessive building-related respiratory symptoms and diseases. Relative extent of water stains, visible mold, mold odor, or moisture can be used to prioritize remediation to reduce potential risk of building-related respiratory diseases. From a public health perspective, these observational findings justify action to correct water leaks and repair water damage in order to prevent building-related respiratory diseases. This approach can also be a basis for developing practical building-diagnostic tools for water-incursion.

Adult↗

PubMed2004

A quasi-linear, viscoelastic, structural model of the plantar soft tissue with frequency-sensitive damping properties.

Little is known about the structural properties of plantar soft-tissue areas other than the heel; nor is it known whether the structural properties vary depending on location. Furthermore, although the quasi-linear viscoelastic (QLV) theory has been used to model many soft-tissue types, it has not been employed to model the plantar soft tissue. The structural properties of the plantar soft tissue were quantified via stress relaxation experiments at seven regions (subcalcaneal, five submetatarsal, and subhallucal) across eight cadaveric feet. The cadaveric feet were 36.9 +/- 17.4 (mean +/- S.D.) years of age, all free from vascular diseases and orthopedics disorders. All tests were performed at a constant environmental temperature of 35 degrees C. Stress relaxation experiments were performed; different loads were employed for different areas based on normative gait data. A modification of the relaxation spectrum employed within the QLV theory allowed for the inclusion of frequency-sensitive relaxation properties in addition to nonlinear elastic behavior. The tissue demonstrated frequency-dependent damping properties that made the QLV theory ill suited to model the relaxation. There was a significant difference between the elastic structural properties (A) of the subcalcaneal tissue and all other areas (p = 0.004), and a trend (p = 0.067) for the fifth submetatarsal to have less viscous damping (c1) than the subhallucal, or first, second, or third submetatarsal areas. Thus, the data demonstrate that the structural properties of the foot can vary across regions, but careful consideration must be given to the applied loads and the manner in which the loads were applied.

Adolescent↗

PubMed1982

In-vivo elastic and damping response of the human leg to impact forces.

The transmission of impact forces in a straight leg from the foot to the level of the greater trochanter was investigated by a two-degree of freedom linear damped-spring model. Foot ground forces measured during a vertical jump and accelerations measured at the level of the greater trochanter were used as model input. The model elastic constant and damping coefficient were determined by solving the dynamic equations of the system. The model was used to predict peak acceleration values for a given input force. Satisfactory prediction of the magnitudes of the first two peaks of the acceleration (maximum difference of 3 percent) was achieved in the two subjects studied.

Adult↗

PubMed2002

The effect of reverberation on the damping of bubbles.

The measurement of an acoustic emission, or scatter, from a bubble is not difficult. However, an accurate interpretation of that signal in terms of the bubble dynamics may require careful consideration. The study presented here is at first sight relatively simple: comparison of the predicted and measured quality factors of injected bubbles. While the measurement is normally done by monitoring the decay of passive emissions from a bubble, this technique becomes difficult with smaller bubbles. Therefore an active technique is introduced, which removes all the frequency-dependent effects on the measurement (such as transducer response) bar one. That, critically, is the effect of the change in the bubble resonance (frequency and damping) which results from the loading on the bubble due to the reverberant field. The vast majority of theoretical treatments of bubble acoustics assume free field conditions, yet the environmental conditions rarely if ever match these. Therefore measurements of bubble damping are compared both with the established free field theory, and with a new theory relevant to the prevailing reverberant conditions (whether caused by tank surfaces, monochromatic neighboring bubbles, or both).

Journal Article↗

PubMed2004

Multimode shunt damping of piezoelectric smart panel for noise reduction.

Multimode shunt damping of piezoelectric smart panel is studied for noise reduction. Piezoelectric smart panel is a plate structure on which a piezoelectric patch is attached with an electrical shunt circuit. When an incidence sound is impinged on the panel structure, the structure vibrates and the attached piezoelectric patch produces an electrical energy, which can be effectively dissipated as heat via the electrical shunt circuit. Since the energy dissipation strongly depends on the vibration mode of the panel structure, many patches are required for multiple vibration modes. Instead of using multiple piezoelectric patches, a single piezoelectric patch is used in conjunction with a blocked shunt circuit for multimode shunt damping. Modeling, shunt parameter tuning, and implementation of the blocked shunt circuit along with an acoustic test of the panel are explained. A remarkable reduction of the transmitted noise was achieved for multiple modes of the panel. Since this technology has many merits in terms of compactness, low cost, robustness, and ease of installation, practical applications in many noise problems can be anticipated.

Acoustics↗

PubMed2006

Active vibration control using an inertial actuator with internal damping.

Collocated direct velocity feedback with ideal point force actuators mounted on structures is unconditionally stable and generates active damping. When inertial actuators are used to generate the control force, the system can become unstable even for moderate velocity feedback gains due to an additional -180 degree phase lag introduced by the fundamental axial resonant mode of the inertial actuator. In this study a relative velocity sensor is used to implement an inner velocity feedback loop that generates internal damping in a lightweight, electrodynamic, inertial actuator. Simulation results for a model problem with the actuator mounted on a clamped plate show that, when internal relative velocity feedback is used in addition to a conventional external velocity feedback loop, there is an optimum combination of internal and external velocity feedback gains, which, for a given gain margin, maximizes vibration reduction. These predictions are validated in experiments with a specially built lightweight inertial actuator.

Journal Article↗

PubMed1985

Bacteriophage phi X174 A protein cleaves single-stranded DNA and binds to it covalently through a tyrosyl-dAMP phosphodiester bond.

The phi X174 A protein cleaves single-stranded DNA and binds covalently to the 5'-phosphorylated end. To determine the nature of the covalent linkage and the amino acid involved, we used the A protein to cleave DNA synthesized in vitro with [alpha-32P]dATP to form the complex of A protein covalently linked to single-stranded DNA. The complex was then digested with DNase I, and the 32P-labeled A protein was isolated by electrophoresis on polyacrylamide gels. The isolated complex was treated extensively with trypsin, and the released peptide-oligonucleotide complexes were incubated with formic acid and diphenylamine (Burton reaction). The Burton reaction caused a transfer of the labeled phosphate from dAMP to the peptide. The labeled phosphopeptides were isolated and hydrolyzed, revealing a linkage of the phosphate to a tyrosine. These results indicate that the A protein cleaves single-stranded DNA and binds covalently to the 5'-phosphorylated terminus by a tyrosyl-dAMP phosphodiester bond.

Bacteriophage phi X 174↗

PubMed1988

Damp housing and childhood asthma: validation of reporting of symptoms.

The relations among parental reports of respiratory symptoms, bronchospasm measured after exercise, and the presence of visible fungal mould in the home was assessed in a population sample of 7 year old children (n = 873). Wheeze in the past year was the symptom most closely associated with reported dampness and particularly with mould. The unadjusted odds ratio relating mould and wheeze was 3.70 (95% confidence interval 2.22 to 6.15), and after adjustment for housing tenure, number of people per room, number of smokers in the household, and gas cooking this remained highly significant (odds ratio 3.00 (1.72 to 5.25)). The reduction in forced expiratory volume in one second after six minutes of free running was used to validate reporting of wheeze. At all levels of measured bronchial lability wheeze was reported more commonly in the children from homes with mould. There was no significant difference in the degree of bronchospasm measured among children from homes with and without mould. Awareness of dampness or mould in the home may be a determinant of parental reporting of symptoms and may account for much of the observed association between mould and respiratory symptoms.

Asthma↗

PubMed2002

Effects of stretch on work from fast and slow muscles of mice: damped and undamped energy release.

Stretching active muscle increases the work performed during subsequent shortening. The effects of a preceding stretch on work done by the undamped or lightly damped series compliance (SC) and by the contractile component (CC), which includes cross bridges and damped elements, were assessed using mouse soleus (slow) and extensor digitorum longus (fast) muscles with limited tendon. Increasing stretch amplitude (0-10% fibre length) increased work done by the SC up to a limit, but did not effect work done by the CC. Increasing stretch velocity (10-100% Vmax) had almost no effect on work done by either component. Increasing the delay between the end of stretch and onset of shortening (0-60 ms) caused a decrease in SC work, with no effect on CC work. Recoil of the SC was responsible for 50-70% of the total work done during shortening after stretch. Usually only 10-40% of the energy imparted during the stretch was recovered as work during subsequent shortening; large stretches and long delays between stretch and shortening further reduced this recovery by one third to one fifth. Results are interpreted in the context of a loss of energy stored in the SC owing to forcible detachment of cross bridges with large stretches and cyclic detachment with long delays.

Animals↗

PubMed1993

Role of a T-type calcium current in supporting a depolarizing potential, damped oscillations, and phasic firing in vasopressinergic guinea pig supraoptic neurons.

Guinea pig magnocellular neurosecretory cells (MNCs) of the supraoptic nucleus (SON) were studied using the in vitro slice preparation. Intracellular recordings were made with biocytin-filled electrodes, permitting immunocytochemical identification of the recorded cells as arginine vasopressin- (AVP) versus oxytocin- (OT) containing. Only AVP cells displaying a depolarizing potential (DP) fired phasically. The DP was associated with a transient inward current measured in voltage clamp, which exhibited a number of properties of the T-type calcium current: activation threshold of -64 mV, time course of up to 250 ms, blockade by nickel and augmentation by barium chloride. This current has not been reported previously in SON neurons. The T-type current (IT) was always associated with a damped oscillation of the membrane following the offset from hyperpolarizing steps. In all cells tested, an apamin-sensitive afterhyperpolarization (AHP) was observed, similar to the calcium-dependent potassium current (IK, Ca) described in rat SON and other CNS regions. Therefore, as with other CNS regions displaying damped oscillations, guinea pig SON cells possess both an IT and an IK, Ca. We have previously described an Ih activating at hyperpolarized potentials in these cells, which depolarizes the membrane to a range in which the IT and IK, Ca can interactively support oscillations. In summary, the IT and associated depolarizing potential appears to be a requisite feature for phasic firing in AVP cells of guinea pig SON.

Animals↗

PubMed2005

Choice of lard, but not total lard calories, damps adrenocorticotropin responses to restraint.

Although rats given the choice of eating high-density calories as concentrated sucrose solutions or lard exhibit reduced responsivity in the hypothalamo-pituitary-adrenal axis, rats fed high-fat diets have normal or augmented responses to stressors. To resolve this apparent discrepancy, we compared in adult male rats the effects of 7-d feeding with lard + chow (choice) to feeding a 50% lard-chow mixture (no-choice) and to chow only. Rats with choice composed diets with 50-60% total calories from lard. Rats were exposed to 30 min of restraint on d 7. In the choice group, there was a robust inhibition of ACTH and corticosterone responses to restraint compared with chow or no-choice groups. Total caloric intake was less with choice than no-choice. Fat depot weights and body weight gain were similar in the high-fat groups. Leptin concentrations were equal but insulin was higher in the choice group. We conclude the following: 1) choice of eating high-density calories strongly damps hypothalamo-pituitary-adrenal responses to stress; without choice, high-density diet is ineffective; and 2) insulin may signal metabolic well-being, and may act through hypothalamic sites to reduce caloric intake but through forebrain sites to damp stress responses.

Adrenal Glands↗

PubMed1988

Correlation between damping coefficients and externally injected currents in oscillations produced by lithium ions in frog skin.

Oscillations in the electrical parameters elicited by Li+ added to the mucosal side of frog skin in vitro were studied under different experimental conditions. The correlation between the damping coefficient and the size of the externally injected current was ascertained. The size of the overall epithelial resistance in NaCl-Ringer seems to be a good indicator of the qualitative behaviour of the skin in the presence of Li+: the higher the resistance the less probable the occurrence of oscillations. Addition of amiloride allowed the calculation of the electromotive force in Na+- and Li+-Ringer. Calculations of the 'total equivalent inductance' and 'total equivalent capacitance' of an oscillating skin were made using resistance values (R), damping coefficients (sigma) and frequency of oscillation (omega).

Animals↗

PubMed2005

Rabi oscillation damped by exciton leakage and Auger capture in quantum dots.

The decoherence of Rabi oscillation (RO) caused by biexciton, population leakage to the wetting layer (WL), and Auger capture in semiconductor quantum dots is theoretically analyzed with multilevel optical Bloch equations. The corresponding effects on the quality factor of RO are also discussed. We have found that the biexciton effect is relatively trifling, as the pulse duration is longer than 5 ps. The population leakage to the WL leads to a decrease of the RO average even though the damping rate is similar to that observed in the experiment. Auger capture in quantum dots results in RO damping that is consistent with the experimental data, which implies that Auger capture is an important decoherence process in quantum dots.

Journal Article↗

PubMed2005

Experimental method for determining the damping parameter of spectral lines emitted by a microwave plasma at atmospheric pressure.

In this work, a simple method for experimentally obtaining the value of the damping parameter or a-parameter of the spectral lines emitted by an argon plasma generated at atmospheric pressure is presented. The value of this coefficient indicates the proportion existing between the Lorentzian and Doppler components of the total line profile, which can be approximated to a Voigt function for our experimental conditions. The a-parameter values found were within the value interval recorded in the literature. The results obtained showed that the damping coefficient of the lines next to the fundamental level remains practically constant along the plasma column, whereas for the spectral lines involving high-lying levels, the a-parameter is sensitive to the changes in the electron density in the plasma. In this work it is also proved that the self-absorption phenomenon induces errors in the calculation of a, due to an increase in the broadening of the line profile produced by this phenomenon.

Algorithms↗