[Resonance interaction of low intensity superhigh frequency radiation in the millimeter range with hemoglobin].
Explore the source record for details and available documents.
Animals↗
SEARCH · PubMed Health
Results for “interaction frequencies”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Training of submaximal working capacity: frequency, intensity, duration, and their interactions.
Explore the source record for details and available documents.
Adolescent↗
Social functioning and overall mortality: prospective evidence from the Kuopio Ischemic Heart Disease Risk Factor Study.
We studied the associations between 11 scales of social functioning and risk of death over an average follow-up time of 71 months in 42- to 60-year-old men in the Kuopio Ischemic Heart Disease Risk Factor Study. In age-adjusted analyses, men were at increased risk of death if they reported few persons to whom they gave or received social support, nonparticipation in organizations, low quality of social relationships, a small number of friends, or not currently being married. Frequency of interaction, shyness, and use of emotional support when troubled were not associated with risk of death; the use of instrumental support when troubled was associated with increased risk. There was little evidence of confounding of these associations by the presence of 31 chronic or acute conditions, perceived health status, or six risk factors. Consistent associations were found in a healthy subgroup. These data add to the growing body of literature linking mortality risk with social functioning, especially in relation to organizational participation and quality of relationships.
Adult↗
[Test battery for objective assessment and differential diagnosis in the early stage of suspected development of presenile dementia of the Alzheimer type].
The clinical diagnosis of organic brain syndromes (especially of primary degenerative dementia) in their early stages is uncertain or only tentative. We used a set of relatively simple tests to support the hypothesis that the disturbance of several operational brain functions precedes memory decline in primary degenerative dementia. Twenty-one patients with early stage, presenile onset of DAT, 14 patients with cardiovascular disease (CVD) and a questionable dementia, an age-matched control group (EC, n = 15), and a younger control group (YC, n = 16) were examined in the following tests: labyrinth learning test, tactile and visual pattern recognition, different reaction time tasks, eye-tracking, finger-tapping, alpha-EEG-blockade, photic driving, flicker fusion frequency, and interaction tasks. The test demonstrated that the patients performed more slowly for all tasks than did control subjects. The CVD patients performed better than the DAT group, but they were also significantly worse in the tests compared with healthy elder subjects. This test battery was found purposeful for early diagnosis of both primary degenerative and other forms of dementia, and may also be helpful to exclude other forms of organic brain syndromes.
Adult↗
Induction of acute inflammatory lung injury by staphylococcal enterotoxin B.
Superantigens stimulate T lymphocytes at high frequency by interacting with appropriate Vbeta segments of the TCR. Challenge of mice with bacterial superantigens such as staphylococcal enterotoxin B (SEB) induces the systemic release of cytokines resulting in septic shock and death of sensitized animals. Analysis of putative pathogenic mechanisms of T cell-dependent septic shock revealed that administration of SEB results in acute inflammatory lung injury characterized by a profound increase in vascular permeability. Injury was associated with marked leukocyte infiltration of the lung and induction of cell adhesion molecules including VCAM-1, ICAM-1, and P-selectin, but not E-selectin. Lung infiltrating leukocytes consisted of granulocytes, mononuclear phagocytes and NK cells with granulocytes representing the major fraction. Consistent with a role of neutrophils as cellular mediators of inflammatory organ injury, we demonstrate activation of circulating granulocytes in mice treated with SEB. When compared with granulocytes of control mice, peripheral blood granulocytes of SEB-treated mice were found to express increased levels of cell surface Mac-1, to down-regulate expression of L-selectin, and to respond with an increased production of toxic oxygen metabolites upon exposure to FMLP. Interestingly, TNF-alpha further enhanced FMLP-induced oxidant production by granulocytes from SEB-treated but not control mice, suggesting that the systemic response to SEB increases granulocyte sensitivity to TNF-alpha-mediated signals. Together, these results suggest that acute inflammatory lung injury may contribute to the pathogenesis of T cell-dependent lethal shock in mice challenged with bacterial superantigens and indicate common pathogenic mechanisms of lung injury induced by a large number of distinct inflammatory stimuli.
Acute Disease↗
Insights into electromagnetic interaction mechanisms.
Low frequency (< 300 Hz) electromagnetic (EM) fields induce biological changes that include effects ranging from increased enzyme reaction rates to increased transcript levels for specific genes. The induction of stress gene HSP70 expression by exposure to EM fields provides insight into how EM fields interact with cells and tissues. Insights into the mechanism(s) are also provided by examination of the interaction of EM fields with moving charges and their influence on enzyme reaction rates in cell-free systems. Biological studies with in vitro model systems have focused, in general, on the nature of the signal transduction pathways involved in response to EM fields. It is likely, however, that EM fields also interact directly with electrons in DNA to stimulate biosynthesis. Identification of an EM field-sensitive DNA sequence in the heat shock 70 (HSP70) promoter, points to the application of EM fields in two biomedical applications: cytoprotection and gene therapy. EM field induction of the stress protein hsp70 may also provide a useful biomarker for establishing a science-based safety standard for the design of cell phones and their transmission towers.
Animals↗
Friendship, social interaction and subjective well-being of older men in an institutional setting.
The relationship of informal social interaction to subjective well-being of older adults was investigated using the PGC Morale Scale, the MACC Behavioral Adjustment Scale, and a sociometric interview which provided measures of peer friendship and frequency of social interaction. Respondents were fifty-four males aged fifty-two to ninety years, who were residents of a Veterans Administration domiciliary. The predicted positive correlation was obtained between morale and frequency of social interaction with persons outside the institution, but men's friendships within the institution were not related to morale. As expected, men who reported overall change in frequency of social interaction scored substantially lower on the PGC Morale Scale than those who perceived no change. Behavioral adjustment ratings of participants made by a staff member were positively correlated with friendship and social interaction scores. The results were thus consistent with a continuity model of aging, in which maintenance of accustomed levels of social interaction is related to subjective well-being.
Aged↗
Migration frequency and the persistence of host-parasitoid interactions.
This paper analyses the effect of migration frequency on the stability and persistence of a host-parasitoid system in a two-patch environment. The hosts and parasitoids are allowed to move from one patch to the other a certain number of times within a generation. When this number is low, i.e. when the time-scales associated with migration and demography are of the same order, host-parasitoid interactions are usually not persistent. When this number is high, however, persistence is more likely. Moreover, in this situation, aggregation methods can be used to simplify the proposed initial model into an aggregated model describing the dynamics of both the total host and parasitoid populations. Analysis of the aggregated model shows that the system reaches a stable steady state for some regions of the parameter domain. Persistence occurs when the movement of the parasitoids is asymmetrical, i.e. they move preferentially to one of the two patches. We show that the growth rate of the host population is a key parameter in determining which migration strategies of the parasitoids lead to persistent host-parasitoid interactions.
Animals↗
Frequency of medical history items, drug interactions, and lifestyle characteristics that may interfere with antiretroviral medications.
PURPOSE: There were two study questions: How often do HIV-infected patients present with a medical history or concurrent medication use that might contraindicate the use of one or more antiretroviral drugs? What is the frequency of patients having lifestyle behaviors that might preclude them from successfully following an antiretroviral drug regimen? METHOD: One hundred patients were given a 52-item questionnaire that asked about their medical histories, concurrent use of non-HAART drugs, and lifestyle. The results were analyzed to determine the frequency of potential side effects, drug interactions, or lifestyle behaviors that could interfere with the patient being able to successfully adhere to antiretroviral drug regimens. RESULTS: 96% of the patients had at least one medical history item or were taking at least one medication that could potentially create a serious side effect to one or more of the 14 antiretroviral drugs that were studied. All of the patients had at least one lifestyle behavior that would have interfered with successful adherence to one or more of the drugs. CONCLUSION: The questionnaire utilized in the study identified potential factors that could cause medical problems or that could interfere with the successful use of various antiretroviral drugs. The frequency of occurrence of these factors was unexpectedly high.
Adult↗
Relation of binaural interaction and spectro-temporal characteristics in the auditory midbrain of the grassfrog.
The relation between binaural interaction type and spectro-temporal characteristics was studied for single units in the auditory midbrain of the grassfrog. Tonal and continuous wideband noise ensembles have been used as stimuli. Spectro-temporal sensitivities were determined for ipsi-, contra- and bilateral stimulus presentation by a closed sound system. Binaural interaction was classified in monaural EO (one ear excitatory), binaural EE (both ears excitatory) and EI (one ear excitatory, the other inhibitory) and purely inhibitory categories. Binaural interaction appeared to be rather invariant to alterations in stimulus intensity and type. A very clear correlation was observed between best frequency and binaural interaction type: EE units are predominantly of high best frequency, whereas EI units are predominantly of low best frequency. The correlation with latency was less significant: EE units tended to have somewhat shorter latencies that EI units. EO units take an intermediate position. Comparisons of ipsi-, contra- and bilateral spectro-temporal sensitivities, revealed differences in best frequency, latency and temporal discharge pattern. In some units a complex interplay of excitatory and inhibitory monaural influences was demonstrated. A number of units was recorded, which were characterized by multiple activation or suppression areas. The majority of these units exhibited frequency-dependent binaural interaction types. In some units it was noticed that binaural interaction type can be dependent on state of adaptation. A comparison of binaural interaction types of neighbouring units provided only weak evidence for a binaural organization in the anuran auditory midbrain, since simultaneously recorded pairs shared the same binaural interaction type only slightly more than expected by mere chance (chi 2-test, P less than 0.10).
Animals↗
Coexistence under positive frequency dependence.
Negative frequency dependence resulting from interspecific interactions is considered a driving force in allowing the coexistence of competitors. While interactions between species and genotypes can also result in positive frequency dependence, positive frequency dependence has usually been credited with hastening the extinction of rare types and is not thought to contribute to coexistence. In the present paper, we develop a stochastic cellular automata model that allows us to vary the scale of frequency dependence and the scale of dispersal. The results of this model indicate that positive frequency dependence will allow the coexistence of two species at a greater rate than would be expected from chance. This coexistence arises from the generation of banding patterns that will be stable over long time-periods. As a result, we found that positive frequency-dependent interactions over local spatial scales promote coexistence over neutral interactions. This result was robust to variation in boundary conditions within the simulation and to variation in levels of disturbance. Under all conditions, coexistence is enhanced as the strength of positive frequency-dependent interactions is increased.
Animals↗
Binaural interaction in brainstem auditory evoked potentials elicited by frequency-specific stimuli.
The frequency specificity of the binaural interaction in brainstem auditory evoked potentials (BAEP) was investigated in ten normal-hearing young adults. A novel stimulus paradigm was devised to reduce the influence of the acoustic reflex (middle ear muscle contraction) on the BAEP, and to minimize the effect of variations in noise level. Sequences of six stimuli (rarefaction clicks or Gaussian-shaped tone pulses with carrier frequencies of 1, 2, 4 and 6 kHz) were periodically presented in the following order: right monaural, left monaural, binaural, left monaural, right monaural, binaural, with an interstimulus interval of 22 ms. Since the sequence of monaural stimuli with binaural stimuli interposed produces a uniform loudness and since the acoustic reflex is a consensual reflex, the relative high stimulus repetition rate (approx. 45/s) causes a muscle contraction which is equal on both sides and rather constant in time. This paradigm turned out to be usable for stimulus intensities as high as 80 dB nHL. The binaural difference potential (BDP) was computed by subtracting the sum of the monaurally (ipsilateral and contralateral) evoked potentials from the binaurally evoked potential. The major binaural interaction occurred in the latency range of BAEP waves V and VI, and there was no evidence of interaction in the earlier portion of the BAEP. Both latency and amplitude of the BDP components were evaluated statistically. The latency of the BDP components - except of the lasted one - showed an almost linear dependence both on stimulus intensity and stimulus frequency. The amplitude grew larger with decreasing frequency, and the visual detection threshold elevated as the stimulus frequency increased. Click stimuli, however, produced the largest amplitudes with lowest visual detection threshold. This novel stimulus paradigm appears to be most suitable for routine clinical investigations since high stimulus intensities can be used.
Brain Stem↗
Chaos synchronization based on a continuous chaos control method in semiconductor lasers with optical feedback.
Chaos synchronization using a continuous chaos control method was studied in two identical chaotic laser systems consisting of semiconductor lasers and optical feedback from an external mirror. Numerical calculations for rate equations indicate that the stability of chaos synchronization depends significantly on the external mirror position. We performed a linear stability analysis for the rate equations. Our results show that the stability of the synchronization is much influenced by the mode interaction between the relaxation oscillation frequency of the semiconductor laser and the external cavity frequency. Due to this interaction, an intensive mode competition between the two frequencies destroys the synchronization, but stable synchronization can be achieved when the mode competition is very weak.
Journal Article↗
Preschoolers' evaluations of physical disabilities: a consideration of attitudes and behavior.
Assessed preschoolers' attitudes about orthopedically handicapped individuals with a standard picture-ranking task. Children generally exhibited a functionally related preference for nonhandicapped individuals. One month later, the same children were videotaped reading and playing basketball with a female adult in a wheelchair or in a chair. Preferences for a normal play partner during reading or during sports on the picture-ranking task did not relate to frequency of social interactions. Liking preference for a normal play partner, in conjunction with gender of the child, predicted frequency of social interactions during both tasks regardless of examiner's handicap status. Thus, the adoption of a negative bias had a general influence; any potential behavioral biases, as reflective of preference biases, were undifferentiated and unfocused in these preschoolers.
Attitude to Health↗
Gender effects on high frequency distortion product otoacoustic emissions in humans.
OBJECTIVE: Gender has been reported to affect many tests of the auditory system, including distortion product otoacoustic emission (DPOAE) group delay and level when elicited with lower frequency stimuli (<8 kHz). Using custom equipment, the effect of gender on DPOAEs at higher frequencies was explored. It is expected that differences in group delay reported at very low frequencies (e.g., 0.78 Hz) will not be replicated at higher frequencies. Additionally, it was hypothesized that female subjects would display larger-level DPOAEs at higher frequencies, based on evidence that female subjects tend to have larger emissions when elicited with lower frequency stimuli. DESIGN: DPOAEs were measured in 37 subjects (20 females and 17 males) with normal behavioral thresholds, middle ear function, and present acoustic reflexes at 1 kHz with contralateral stimulation. Behavioral thresholds were measured through 16 kHz using Békèsy tracking. Ratio and frequency sweeps were used to calculate DPOAE group delay and measure DPOAE levels, respectively. Ratio sweeps were obtained at f2 frequencies of 1, 2, 4, 8, 10, 12, 14, and 16 kHz, with L1 = 60 and L2 = 45 dB SPL, with the ratio (f2/f1) varied from 1.11 to 1.3. Frequency sweeps were measured with L1 = 60 and L2 = 45 dB SPL and an f2/f1 of 1.2 at discrete f2 frequencies between 1 and 16 kHz. Data were subjected to repeated-measures analysis of variance. RESULTS: Significant frequency-by-gender interactions were found for group delay (for data from 1 to 8 kHz) and level (for data from 9 to 15 kHz). The frequency-by-gender interaction and the main effect of gender were not significant for the behavioral results. CONCLUSIONS: Gender-based norms for auditory-evoked potentials measures are standard in clinical settings. The results of the present study, in agreement with previous studies, indicate that significant interactions exist between gender and DPOAE group delay values in the lower frequencies, and between gender and DPOAE levels at the higher frequencies. To reach the goal of using high frequency DPOAEs in clinical protocols, such as for auditory neuropathy/dys-synchrony diagnosis and ototoxicity monitoring, DPOAEs elicited with conventional and higher frequency stimuli must be understood, including the role of gender to determine if an effect on clinical protocols would exist.
Adolescent↗
Frequency dependence of interear asymmetries and binaural interaction in the human ABR.
In the present study derived auditory brain stem responses utilizing high pass masking were used to determine the frequency dependence of interear asymmetries and binaural interaction. Eight female adults with normal hearing participated in this study. The ABR was recorded for right and left ears and binaurally with clicks alone and in the presence of high pass masking noise with the following cutoff frequencies: 4000, 2000, 1000, and 500 Hz. Derived responses were obtained by successive waveform subtractions and were analyzed for significant right/left asymmetries, for latency and amplitude, utilizing a statistical method discussed by Spivak (unpublished doctoral dissertation, City University of New York, 1985). The binomial test revealed that the frequency of latency and amplitude asymmetries was not significantly above chance levels for the unmasked measures or for any of the derived bandwidth measures. The binaural interaction component (BIC) was obtained utilizing the method proposed by Dobie and Berlin (Arch Otolaryngol 1979; 105:391-398), and was expressed as a percentage of the true binaural. Analysis of variance revealed no significant differences in the ratio of the BIC amplitude to the true binaural amplitude as a function of the high pass masking cutoff frequency. The present data suggests that for the frequency bandwidths analyzed in this study, there are no specific frequency dependencies of interear asymmetries or binaural interaction in the human ABR.
Adult↗
Event-related potentials and the recollection of low and high frequency words.
A recognition memory test was conducted in which low and high frequency words were initially presented in one of two different study tasks. A word was defined as recollected if, at test, it was both confidently judged 'old', and confidently assigned to its correct study context. Low frequency words were more accurately recognised than high frequency items, and were also more likely to be assigned to their correct study context. The results are consistent with the view that low frequency words are better recognised because they are more likely to be recollected, rather than because they engender higher levels of relative familiarity. Event-related potentials (ERPs) evoked at test by correctly classified new words were contrasted with those evoked by old, recollected words. The ERPs to low frequency words exhibited large and reliable 'old/new' effects, in that from approx. 300 msec post-stimulus, waveforms were more positive-going for old than for new items. These effects were markedly smaller, and indeed non-significant, in the ERPs evoked by high frequency items. The results show that the interaction between word frequency and old/new differences in ERPs does not arise because of a confound between frequency and the probability of recollection. Together with other findings, they suggest that recollection is better conceived of as a graded, rather than as an all-or-none phenomenon.
Adult↗
[Pharmacological interactions of statins].
OBJECTIVE: To determine in primary care the frequency of pharmacological interactions of statins. DESIGN: Transversal observational study.Setting. Urban health centre.Participants. 384 patients taking statins who were chosen by systematic sampling based on long-treatment cards (95% CI, accuracy 5% and expected proportion of possible interactions unknown). MAIN MEASUREMENTS: Consumption of statins, the accompanying medication taken, presence of interactions according to the technical details of statins (Spanish Medication Agency, Ministry of Health and Consumption) and social and demographic variables. RESULTS: In 55 patients (14.3%) (95% CI, 10.8%-17.8%) one of the statin interactions with the other drugs was checked, especially with acenocoumarol, digoxin and anti-acid drugs. In patients with some interaction, the mean number of other drugs was significantly higher (4.51.5 vs 3.31.9 SD; P<.001). 19.1% of men and 10.8% of women showed interactions, the difference being statistically significant (P=.02). By means of logistic regression, both masculine gender (OR=1.8) and taking of other medication in quantities of 5 or more (OR=2.7) appeared as variables associated with the presence of interactions. CONCLUSIONS: The potential pharmacological interactions of statins reach 14.3% of patients with hypercholesterolaemia who take medication long-term. The possibility of reaching high plasma concentrations of statins and/or of modifying the therapeutic effect of various drugs enables a more appropriate use of statins to be recommended, with prescription of those statins that metabolise less through the P450 cytochrome.
Adult↗