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PubMed1977

[Damping of oscillations in arterial pressure in the internal carotid arteries].

In dogs, recording of fluctuations of the inlet and outlet pressure in the internal carotid artery showed a decrease of the amplitude of fluctuations along the artery, the damping index (Id) being about 60-90%. The Id was almost unchanged when the skull was either intact or largely opened. The amplitude of blood pressure fluctuations in the circle of Willis was always decreased after occlusion of the vertebral arteries, being evidently unrelated to superposition of the pulse waves that reach the circle of Willis through the internal carotid and the vertebral arteries. Therefore the decrease of the amplitude of pulsation was dependent on the damping of the pulsatile waves along the internal carotid arteries. The rise of the tone of the latter increased the Id, and vice cersa. The Id was almost independent of the size of amplitude and of the frequency of the fluctuations of the systemic arterial pressure, but decreased when the latter rised.

Animals↗

PubMed1993

Home dampness and molds as determinants of respiratory symptoms and asthma in pre-school children.

The objective of our study was to assess the occurrence of respiratory symptoms in relation to dampness and molds in dwellings in pre-school children. A population-based cross-sectional study was carried out by mailing a parent-administered questionnaire to a random sample of children in a source population consisting of all children aged 1 to 6 years of Espoo, an urban-suburban city (pop. 170,000) in the Helsinki metropolitan area. The study population included a total of 2568 children whose parents filled the questionnaire (response rate 80%). Included were questions on respiratory health, partly modified from ATS-DLD-78-C questionnaire, and potential personal and environmental determinants of the outcome. The determinants of interest were histories of water damage, presence of moisture and visible molds and perceived mold odor at home. The outcomes included persistent cough, phlegm and wheezing, persistent nasal congestion and excretion during the past 12 months and current asthma. The determinant-outcome relations were estimated in the logistic regression controlling for age, gender, parents' education, single parent or guardian, environmental tobacco smoke, gas cooking, pets and type of day care. The occurrence of persistent cough (OR 2.17; 95% CI 1.39, 3.39), phlegm (2.20; 1.27, 3.82), wheezing (2.62; 1.39, 4.39), nasal congestion (1.94; 1.15, 4.98), and nasal excretion (1.43; 0.95, 2.17) during the past year were higher with the presence of any determinant, but the occurrence of asthma (OR 1.10; 0.54, 2.24) was similar compared to the reference group. Mold odor during the past year (ORs from 2.38 to 6.87) and water damage over a year ago (ORs from 2.54 to 8.67) had the strongest association with the respiratory symptoms. A dose-response relation of the occurrence of the symptoms associated with the frequency of days with mold odor was observed. There was also a compatible time sequence between water damage taking place more than a year ago and the occurrence of symptoms during the past year. The results provide further evidence on the importance of home dampness and molds in the etiology of respiratory symptoms and new information on the role of mold odor as a risk indicator.

Asthma↗

PubMed2005

Synchrotron radiation circular dichroism spectroscopy of ribose and deoxyribose sugars, adenosine, AMP and dAMP nucleotides.

Synchrotron radiation circular dichroism (SRCD) spectra of ribose and deoxyribose sugars, adenosine, AMP and dAMP nucleotides and cyclic derivatives were measured in the vacuum ultraviolet region (down to 168 nm for sugars and 175 nm for adenine derivatives) and at different pH values (3, 6-7, 9-10) and temperatures (between 5 and 45 degrees C). The information content in the VUV region is important since the CD bands strongly depend on the chemical structure of the sugar, the presence and orientation of a phosphate group and the protonation state of adenine. On the other hand, single or double deprotonation of the phosphoric acid group has no influence on the spectra. We assign the vacuum ultraviolet (VUV) CD bands of the nucleoside and nucleotides to be due mainly to n-->pi* transitions in the adenine nucleobase based on a comparison with the absorption spectra. The CD bands of the sugars are due to n(O -->sigma*) transitions and are much smaller than the CD signal from the nucleotides in the VUV region. Bands are assigned to both pyranose and open-chain forms.

Adenosine↗

PubMed2005

Orthogonal trap time-of-flight mass spectrometer using a collisional damping chamber.

We report a new hybrid mass spectrometer, which is a combination of a quadrupole ion trap and an orthogonal time-of-flight (TOF) mass spectrometer. This new configuration consists of a collisional-damping chamber (CDC) inserted between an MSn-capable ion trap and a high-mass-accuracy orthogonal-TOF mass spectrometer. Because the CDC converted an ion packet into an energy-focused and quasi-continuous beam, a high mass resolution of over 10,000 and a high mass accuracy of better than 3 ppm were achieved. Moreover, the ratio of the maximum detectable m/z to the minimum detectable m/z, which is referred to here as the mass window, was improved to more than 10.

Polyethylene Glycols↗

PubMed2001

Iterative lineshape analysis of quadrupolar echo spectra of a damped CD(3) quantum rotor: preliminary evidence of a novel mechanism of stochastic spin exchange.

It is demonstrated that the wealth of information about damped quantum rotation of CD(3) groups, contained in quadrupolar echo spectra, can be fully explored in a broad temperature range using a method of iterative analysis of the spectral lineshapes. The recently reported lineshape equation which, apart from the quantum tunneling and the dissipative Alexander--Binsch terms, contains an additional dissipative term having no classical analog is shown to be capable of describing even subtle details of the spectra of a crystal of acetylsalicylic acid--CD(3) oriented specifically in the magnetic field. Preliminary evidence of the occurrence of this novel dissipative mechanism in the system studied is reported. The results obtained seem to suggest that there is no "classical limit" in the dissipative behavior of this system.

Journal Article↗

PubMed1988

Phase I clinical trial and human pharmacokinetics of 2,4-diamino-5-adamantyl-6-methyl pyrimidine ethane sulfonate (DAMP-ES): a lipid-soluble antifolate.

A phase I and pharmacokinetic study of a novel lipid-soluble antifolate, 2,4 diamino-5-adamantyl-6-methyl pyrimidine ethane sulfonate (DAMP-ES) has been carried out on two schedules: I--daily x5; II--24-h continuous infusion. In schedule I, doses of 10-90 mg/m2 per day were evaluated. Dose-limiting toxicity was hematologic, but nausea and vomiting, skin rash, diarrhea, anorexia, alopecia, mucositis, and neurotoxicity were also noted. In schedule II, doses of 192 and 240 mg/m2 were evaluated. Dose-limiting toxicity was neurotoxicity, but hematologic toxicity was also marked. Recommended starting doses for phase II studies are 75 mg/m2 per day for 5 days or 192 mg/m2 by continuous infusion for 24 h. Pharmacokinetic studies indicated a beta-phase plasma half-life of 12.4-24 h and a large and variable volume of distribution.

Adamantane↗

PubMed1983

In vitro initiation of bacteriophage phi 29 and M2 DNA replication: genes required for formation of a complex between the terminal protein and 5'dAMP.

Cell-free extracts prepared from phi 29 and M2-infected Bacillus subtilis cells catalyse the formation of complexes between terminal protein and [alpha-32P]-dAMP in the presence of [alpha-32P]-dATP, MgCl2, ATP, and phage DNA with terminal protein covalently linked at both the 5'ends. The complex formation does not take place when proteinase K-treated DNA is added or when uninfected extract is used. The phi 29 complex thus formed is smaller than the M2 complex, primarily due to the different molecular weights of the respective terminal proteins. Extracts prepared from cells infected with suppressor-sensitive mutants of genes 2 or 3 of phi 29 or genes G or E of M2 do not support complex formation. When the pair of extracts of phi 29 or M2-infected cells are mixed, however, formation of the complex takes place as a result of in vitro complementation. These results indicate that the complex formation observed in vitro reflects in vivo initiation of phage DNA replication. The product of gene 2 of phi 29 may be the enzyme that catalyses formation of the complex.

Adenosine Monophosphate↗

PubMed1985

Linear model of brain electrical activity--EEG as a superposition of damped oscillatory modes.

EEG time series were modeled as an output of the linear filter driven by white noise. Parameters describing the signal were determined in a way fulfilling the maximum entropy principle. Transfer function and the impulse response function were found. The solutions of the differential equations describing the system have the form of the damped oscillatory modes. The representation of the EEG time series as a superposition of the resonant modes with characteristic decay factors seems a valuable method of the analysis of the signal, since it offers high reduction of the data to the few parameters of a clear physiological meaning.

Animals↗

PubMed1985

Quantitation of a mass action of dopaminergic neurones regulating temporal damping of linear electrocortical waves.

We have previously proposed that electrocortical waves are linear waves, subject to regulation by mesotelencephalic dopaminergic neurones. As a further means to test this theory, selective unilateral lesions of varying extent were made in the nucleii of origin of the dopaminergic mesotelencephalic tract. Changes in the electrocortical power spectrum were assessed by a repeated measure, between hemispheres comparison of ratio changes in power. With increasing unilateral dopamine cell damage, the animals showed increasing contralateral sensorimotor neglect. Curve fitting the ratio changes in power attributable to lesion, showed that estimates of the power of driving signals and the temporal damping moved in reverse directions with increasing extent of lesion, as expected from the theory. A further test was undertaken, to determine whether equal estimates for a transformation of surface signals were obtained from each side. Equality would not be expected if the equation for relative power were invalid. Left and right equality was found for three grades of unilateral lesion.

Animals↗

PubMed1994

Enhanced sensitivity of rapidly exchanging amide protons by improved phase cycling and the constructive use of radiation damping.

Two alternative, general methods are presented that lead to enhanced signal intensity of rapidly exchanging protons. Both methods work by avoiding saturation of the water resonance, and are convenient to implement since they do not use any selective pulses. One method carefully chooses proton pulse phases and gradient strength and position in such a way that the water is realigned along the +z axis at the beginning of the acquisition time. An alternative method is proposed for cases where the pulse sequence does not allow such phase cycling. The latter uses radiation damping to bring water back to the +z axis 20-30 ms after acquisition. The methods are applied to the triple-resonance experiments HNCA, HNCO and HN(CO)CA. Both methods require pulsed B0 field gradients and can result in higher signal intensity by a factor of two or more.

Magnetic Resonance Spectroscopy↗

PubMed1985

Contributions of noradrenergic neurones of the locus coeruleus to the temporal damping of linear electrocortical waves.

The preceeding paper (Wright et al. 1985a) gives evidence that mesotelencephalic dopaminergic neurones regulate gross electrocortical waves with linear properties, by influencing the strength of their driving signals and temporal damping. The present study further generalises the findings to ascending noradrenergic neurones, which have different fields of termination to dopaminergic fibres. It is shown that: Estimates of the major groups of natural frequencies for the telencephalic system obtained from curve-fitting the ratio changes in the power spectrum attributable to unilateral noradrenergic neurone lesion, are again centered about the frequencies of the major cerebral rhythms. Estimates of electrode transfer characteristics, using parameters obtained from curve fitting ratio changes in power, in conjunction with the raw left and right power spectra, are again found to be equal left and right, as required by the theoretical derivation. Changes in relative amplitude of electrocortical waves and their relative phase are significantly in accord with the relationship expected from theory.

Animals↗

PubMed1976

The damped pendular rotation test in central vestibular disorders.

Nystagmic rhythm in the damped pendular rotation test (DPRT) was analysed electronystagmographically both in healthy subjects (control) and patients with peripheral and central vestibular lesions. The patients were tested in a semi-dark room with eyes open and, in addition, a serial subtraction task was performed to maintain the state of alertness throughout the rotation. In the controls 49 years of age and under dysrhythmia was found in 11%, while in persons 50 years of age and over the abnormal rate was 29%. In patients with acoustic tumors, who had undergone surgery in which the translabyrinthine and middle fossa approach had been utilized, dysrhthmia was present post-operatively in only a few cases. In patients 49 years of age and under, operated on through the suboccipital approach, dysrhythmia was found post-operatively, or was at least more remarkable than pre-operatively in most cases. Nystagmic rhythm was, on the other hand, regular with cerebellar degenerative process or atrophy. Pre-operative dysrhythmia in patients with cerebellar and cerebral tumors was in some cases post-operatively converted to regular rhythmic nystagmus in pendular stimulations. Therefore, in cerebellar and cerebral tumors, dysrhythmia was thought to be due to secondary effects in brainstem, as these tumors can cause intracranial hypertension and circulatory disturbances in surrounding brain tissues. In Menière's disease and sudden deafness, dysrhythmia and salvos in DPRT were found in the age groups, 49 years of age and under and 50 years and over, as frequently as in the healthy and control group. In one case with Menière's disease which showed dysrhythmia, labyrinthectomy was done. This surgical manipulation of the labyrinth did not eliminate dysrhythmia, though a temporary improvement was obtained. This result indicates that the dysrhythmia may be of central origin. These findings also suggest that nystagmic rhythm in DPRT with mental arithmetic is significant in assessing brainstem dysfunctions, when the age and state of alertness of the patient are taken into consideration, or when comparing the pre- and post-operative findings in intracranial lesions.

Adolescent↗

PubMed1981

Effects of ocular fixation on perrotatory nystagmus in damped pendular rotation test.

Effects of ocular fixation on pendular rotation nystagmus were investigated in 65 patients. There were 25 with peripheral vestibular or vestibulo-cochlear disorders, 17 with central vestibular disorders, five with congenital nystagmus, 16 patients over 60 years old with vertigo in whom peripheral vestibular disorders were ruled out, however, the causes were unknown. Damped pendular rotation test (DPRT) was performed both under darkness and employing mental arithmetic and under ocular fixation. These findings were related to those of caloric vestibular suppression test (VST) by Takemori and those of optokinetic pattern test (OKP), eye tracking test (ETT), and spontaneous nystagmus. Thirteen of 17 patients with central vestibular disorders and five with congenital nystagmus showed loss of visual suppression during ocular fixation in DPRT, whereas in cases of peripheral lesions, visual suppression was observed. Loss of visual suppression during ocular fixation in DPRT was often seen in cases of brainstem and cerebellar lesions. In brainstem lesions, perrotatory nystagmus was evoked during ocular fixation, whereas no nystagmus was seen in darkness with eyes open. In cerebellar lesions, perrotatory nystagmus was partly suppressed or decreased during ocular fixation. Relationships between the direction of the visual suppression during ocular fixation in DPRT and the side of the lesion were not apparent. Ocular fixation test in DPRT has a diagnostic value not only for central lesions, but for differentiating brainstem lesion from cerebellar lesion with the findings in DPRT under darkness. The findings under ocular fixation in DPRT are closely related to those of VST in cases of caloric nystagmus.

Adult↗

PubMed2004

Investigation of newly developed added damping and stiffness device with low yield strength steel.

Energy dissipators, isolated-resistant and specific structural forms for earthquake resistance are popular topics in the research to improve shock-resistance. In this work, experimental methods were used to investigate the property of low yield strength steel. Carbon content in LYS material is lower than that in other steels; the ultimate stress is three times the yield stress. The ultimate elongation rate is about 62% and the ductility is 2-3 times that of A36 steel. In order to overcome some defects of ordinary use metallic dampers, the mechanical characteristic of low yield strength steel is used to develop added damping and stiffness for rhombic steel plate absorber. Test of the energy dissipation behavior for this newly developed device indicated that LYS could stably dissipate or absorb the input energy of earthquake. Then, the analytical model for the hysteretic behavior of this new device is proposed. Comparison of experimental data and numerical simulation results showed that this analytical model is suitable for simulating the hysteretic energy behavior of this new device.

Compressive Strength↗

PubMed2003

Mandibular morphogenesis during soldier differentiation in the damp-wood termite Hodotermopsis sjoestedti (Isoptera: Termopsidae).

The conspicuous morphogenesis during termite soldier differentiation is one of the most remarkable examples of specialized caste development in social insects. To clarify the mechanism of morphological changes during soldier differentiation, mandibular morphogenesis prior to the presoldier moult was examined in the damp-wood termite Hodotermopsis sjoestedti. Using experimental induction of presoldier differentiation from pseudergates (7th or later instar larvae) by the application of juvenile hormone analogue (JHA), we compared mandibular morphogenesis in a presoldier moult (from pseudergate to presoldier) with that of a stationary moult (from pseudergate to pseudergate). Future presoldier mandibles were formed under the old mandibular cuticle of the pseudergates just prior to the presoldier moult. Multiple folds of both epidermis and new cuticle were observed in the developing mandible, and large concavities between teeth were formed on the mandibular surface. While in the stationary moult, the future mandibles were formed with a smooth surface. The process of the mandibular morphogenesis in soldier differentiation explains the allometry of soldier mandibles. The morphological differences in mouth parts between castes arise from a switching mechanism that triggers caste-specific mandibular epithelial growth during development.

Animals↗

PubMed2004

NMR measurements of diffusion in concentrated samples: avoiding problems with radiation damping.

Pulsed field gradient spin echo NMR is generally the method of choice for diffusion measurements on liquid samples. With modern high field instruments, however, severe problems can arise when it is applied to samples with very high proton concentrations because of the presence of radiation damping. The problems may be greatly reduced by a suitable choice of experimental parameters, in particular the use of modified stimulated echo pulse sequences with a reduced flip angle for the first pulse.

Journal Article↗

PubMed1985

Effect of damped sine-wave shocks on catheter dielectric strength.

This study evaluated the ability of 24 new standard tripolar and quadripolar U.S. Catheter Instruments catheters to withstand a single damped sinusoidal shock delivered by a standard defibrillator. The schema for energy delivery was meant to simulate possible clinical practices. Delivered peak voltage and current were measured during each shock. Each electrode was examined for pitting and changes in line resistance as a consequence of the shock. Electrode pitting occurred on all selected anodal poles. However, it also was found on "unsolicited" electrodes from 7 catheters, indicating that current had followed unanticipated routes. Electrode line resistance was unmeasurable in 6 of these 7 inappropriately pitted electrodes. Delivered peak voltage and postshock catheter dielectric strength depended on the manner of energy delivery. To simulate a posterior septal accessory pathway ablation procedure, a shock was delivered to 2 proximal (anodal) poles in 16 quadripolar catheters (8 received 200 J and 8 received 360 J). Delivered peak voltage was 3,125 +/- 362 V for the 200-J shock and 4,100 +/- 160 V for the 360-J shock. Postshock catheter dielectric strength for the 200- and 360-J shock was 1,425 +/- 826 V and 601 +/- 707 V, respectively. This was significantly lower than peak delivered voltage (p less than 0.001 for either energy). To simulate His bundle or ventricular tachycardia focus ablation, 8 tripolar catheters each received a single 200-J shock to the tip electrode. This resulted in a delivered peak voltage of 2,900 +/- 351 V, compared with a postshock dielectric strength of 1,325 +/- 1,320 V (p less than 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Catheterization↗

PubMed1984

Damped oscillation in the ampullary electroreceptors of Plotosus involves Ca-activated transient K conductance in the basal membrane of receptor cells.

K-blockers suppressed damped oscillation of Plotosus electroreceptors in situ. Ca-blockers abolished V-dependent non-linear responses, as well, and shifted the DC level in the ampulla by ca. -1 mV. Thus, the in situ receptor is held depolarized with maintained Ca current in the basal membrane of receptor cells. The oscillation involves Ca-activated transient K current in the same membrane, which contributes to the initial sensory adaptation, and presumably also to stabilizing the sensitive receptors.

Animals↗