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PubMed1992

Induced oviposition of precalcified eggs following prostaglandin administration.

In order to obtain fertilized ova from White Leghorn chickens in the early cleavage stages, a nonsurgical procedure using prostaglandins (PG) was developed to induce premature oviposition of uncalcified eggs. The experimental design consisted of two 5 x 5 factorial arrangements of treatments using combinations of 0, .5, 1, 2, and 3 micrograms of PGF2 alpha and PGE1 or PGF2 alpha and PGE2. Frequency of PG-induced oviposition was highest (100%) with 1 microgram of PGF2 alpha and 3 micrograms of PGE1 or PGE2. Induced oviposition frequency decreased at the higher (2 and 3 micrograms of each PG) dosages. In general, induction time decreased as PG levels were increased; the minimum induction time was observed with injection of 3 micrograms of PGF2 alpha with 2 or 3 micrograms of PGE1 (1.8 min). There was a significant interaction for frequency of induced oviposition between PGF2 alpha and PGE1 (P less than .05), but not between PGF2 alpha and PGE2. There was also a significant interaction between PGF2 alpha and PGE2 (P less than .01) for induction time, which was not observed with PGF2 alpha and PGE1. Oviposition could not be induced earlier than 5 to 5.5 h after the previous oviposition. Prostaglandin-induced oviposition provides an alternative to euthanasia, surgery, or manual expulsion for collection of precalcified eggs in the early cleavage stages.

Alprostadil↗

PubMed1989

The impact of a resident dog on an institution for the elderly: effects on perceptions and social interactions.

A longitudinal case study was made of a sub-unit of a nursing home to examine the perceptions and social interactions of patients and staff after introduction of a resident dog. A behavioral mapping procedure was used to determine staff and patient interactions 6 weeks before and 6 weeks and 22 weeks after the dog's arrival. Interviews were also conducted with patients and staff. Six weeks after the dog's arrival, a significant increase in frequency of interactive behaviors was seen for both staff and patients. By 22 weeks, behaviors for patients had reverted to base-line levels, while remaining high for staff.

Aged↗

PubMed1993

Intermodulation distortion (F2-F1) in inner hair cell and basilar membrane responses.

Round window (RW) recordings in guinea pigs show a large response at the frequency of the quadratic difference tone (QDT) at F2-F1 for high-frequency (> 8 kHz) tone pairs. The magnitude of the RW response is dependent on frequency and level of the primaries. The QDT cochlear microphonic produced is largest for primaries with a frequency separation of approximately 900 Hz. Its source is probably the local activity of hair cells in basal cochlear locations where the high-frequency tones interact. QDT measurements from locations inside the organ of Corti show that the magnitude of the QDT is largest in the inner hair cell (IHC) region and monotonically increases as the difference in the frequency of the primaries decreases. Measured as IHC intracellular ac receptor potential, the QDT appears to be the result of a mechanical stimulus to the cell rather than as an inherent property of the nonlinear transduction in the IHC. However, QDT of the same form is not evident in the velocity responses of the basilar membrane. These results suggest that the outer hair cells (OHC) produce a strong quadratic distortion product mechanical force to stimulate inner hair cells. This mechanical drive may not be present, or is a weak component, in basilar membrane motion.

Acoustic Stimulation↗

PubMed1986

Monaural auditory adaptation of reaction times at .5, 1, and 3 kc/s.

All procedures to measure auditory adaptation depend at least indirectly upon some subjective judgment of loudness, with the exception of the reaction-time (RT) study of Davis and Weiler (Brit. J. Audiol., 1976, 10, 102-106). We used a variant of the Davis-Weiler RT method to measure monaural adaptation at the end of tones of 7 min duration at .5, 1, and 3 kc/s at 60 db SPL, in 62 normal-hearing young adults. Adaptation was expressed as an increase in RT in msec post- vs pre-adaptation in response to a 1-sec probe tone at 10 kc/s at 70 db SPL presented simultaneously with the adapting tone, either (1) in the middle of a 2-sec burst of the adaptation tone prior to the beginning of the 7-min adaptation session (pre-adaptation measure), or (2) during the last seconds (S alerted) of the continuing adaptation tone (post-adaptation measure). Significant pre-post RT differences, collapsed over pre-post measures and over ears, were found at all 3 frequencies (p less than .0001), indicating that the Monaural Heterophonic RT (MHRT) procedure can indeed be used as an objective measure of auditory adaptation. The mean RTs across pre- and post-adaptation measures were 221.9, 217.6, and 228.0 msec in the usual frequency order, significantly different (p less than .0001). Adaptation (i.e., increased RT after 7 min of adaptation) at .5, 1, and 3 kc/s was 36.9, 28.5, and 21.6, respectively. This effect introduced a significant interaction between frequency and adaptation (p less than .001). To transfer from auditory adaptation in reduced RT in msec by the MHRT method to adaptation in reduced phons in db, it will be necessary to construct, perhaps for every S, a table of RTs for a sufficient selection of levels at the relevant frequencies.

Acoustic Stimulation↗

PubMed1981

Mutagenic interactions between near-ultraviolet (365 nm) radiation and alkylating agents in Escherichia coli.

The mutagenic interaction between near-ultraviolet (365 nm) radiation and the alkylating agents ethyl methanesulphonate (EMS) and methyl methanesulphonate (MMS) was studied in a repair-competent and an excision-deficient strain of Escherichia coli. Near-UV radiation modified the metabolic response of exposure to these chemicals and either reduced or increased their mutagenic efficiency. Based on these results, an experimental model was formulated to explain the mutagenic interactions that occur between near-UV and various agents that induce prototrophic revertants via error-prone repair of DNA. According to this model, low doses of near-UV provoke conditions for mutation frequency decline (MFD) and lead to a mutagenic antagonism. With increasing near-UV doses, damage to constitutive error-free repair systems increases, favouring the error-prone system and inhibiting the MFD. Under these conditions there will be a progressive decrease in antagonism until at high doses an enhancement of mutation frequency (positive interaction) will occur.

DNA Repair↗

PubMed2002

Spectral contributions to the benefit from spatial separation of speech and noise.

Speech recognition in noise improves when speech and noise sources are separated in space. This benefit has two components whose effects are strongest in different frequency regions: (1) interaural level differences (e.g., head shadow), which are largest at higher frequencies, and (2) interaural time differences, which have their greatest contribution at lower frequencies. Binaural interactions enhance the separation of signals from noise through the use of these interaural differences. Here, the benefit attributable to spatial separation was measured as a function of the low- and high-pass cutoff frequency of speech and noise. Listeners were younger adults with normal hearing, older adults with normal hearing, and older adults with hearing loss. Binaural thresholds for narrowband noises were measured in quiet and in a speech-shaped masker as a function of masker low-pass cutoff frequency. Speech levels corresponding to 50% correct recognition of sentences from the Hearing in Noise Test (HINT) were measured in a 65-dB SPL speech-shaped noise. Thresholds for narrowband noises and for speech were measured with two loudspeaker configurations: (1) signals and speech-shaped noise at 0 degrees azimuth (in front of the listener) and (2) signals at 0 degrees azimuth and speech-shaped noise at 90 degrees azimuth (at the listener's side). The criterion measure was spatial separation benefit, or the difference in thresholds for the two conditions. Benefit of spatial separation for unfiltered speech averaged 6.1 dB for younger listeners with normal hearing, 4.9 dB for older listeners with normal hearing, and 2.7 dB for older listeners with hearing loss. Benefit was differentially affected by low-pass and high-pass filtering, suggesting a trade-off of the contributions of higher frequency interaural level differences and lower frequency interaural timing cues. As expected, older listeners with hearing loss benefited little from the improved signal-to-noise ratios in the higher frequencies resulting from head shadow, but showed some benefit from lower frequency cues. Spatial benefit for older listeners with normal hearing was reduced relative to benefit for younger listeners. This result may be related to older listeners' elevated thresholds at frequencies above 6.0 kHz.

Adult↗

PubMed2001

Relations among age, income, and knowledge of investments.

This study examined consumers' interactions with financial advisors in terms of the age and income of the respondents. The respondents were 500 residents of Florida interviewed in a random telephone survey. The dependent variables for the analysis were (1) frequency of communication, (2) knowledge, and (3) confidence in investment. No significant differences were found for frequency of interaction, but differences were identified on both knowledge and confidence in investment. Older respondents had more knowledge about investment than did younger ones, and respondents of higher income had more knowledge and more confidence in their investments than did those of lower or middle income. The results are discussed in terms of immediacy theory. Investment issues would have more immediacy for higher income respondents since they would have more money available for investment. Similarly, immediacy would be higher for older respondents since they would have more time and interest to devote to investment issues.

Age Factors↗

PubMed1998

Psychotherapeutic agents in older adults. Metabolism, bioavailability, and drug interactions.

This article presents clinically relevant drug interactions which may confront the geriatric psychiatrist. Changes in drug metabolism due to aging, higher medical comorbidity, and frequent polypharmacy all place the older patient at a greater risk of developing a drug-drug interaction. Clinicians must be aware of the potential for such interactions, but they should also be able to determine which of those possible interactions is appropriate for a particular patient. Drug interactions are included in this article based on frequency of the interaction, clinical severity, and frequency of contact with the drugs prescribed by the practicing clinician.

Age Factors↗

PubMed1991

Primary family contacts and emotional health in the institutionalized elderly.

Research among nondemented elderly living independently in the community suggests that increased social support is associated with improved emotional and physical health. Relatively little research has examined associations between social supports and health among the institutionalized elderly. A sample of 70 nondemented, elderly nursing-home patients was studied to determine associations between qualitative and quantitative aspects of patients' relationships with their primary family contact and measures of emotional well-being, including depression, hopelessness, and life satisfaction. Significant correlations between quality of relationships and all domains of emotional well-being were found. None of the correlations between frequency of interaction and measures of emotional health were significant. A hierarchical regression analysis demonstrated that the correlation between quality of relationships and depression and life satisfaction was independent of functional status, mental status, age, type of relation, and frequency of visits. These results are consistent with studies of the noninstitutionalized elderly.

Aged↗

PubMed2006

Interaction of polar molecules with resonant radio frequency electric fields: imaging of the NO molecular beam splitting.

The interaction between a NO supersonic beam and a resonant radio frequency (RF) field is investigated using laser ionization coupled to imaging techniques. It is shown how the resonant interaction leads to a beam splitting of +/-0.2 degrees toward both positive and negative direction perpendicular to the beam propagation axis. This phenomenon is rationalized using a model based on molecular interferences produced by the action of the resonant RF electric field.

Journal Article↗

PubMed1992

Microbial predation in a periodically operated chemostat: a global study of the interaction between natural and externally imposed frequencies.

Predator-prey systems in continuously operated chemostats exhibit sustained oscillations over a wide range of operating conditions. When the chemostat is operated periodically, the interaction of the natural oscillation frequency with the external forcing gives rise to a wealth of dynamic behavior patterns. Using numerical bifurcation techniques, we perform a detailed computational study of these patterns and the transitions (local and especially global) between them as the amplitude and frequency of the forcing vary. The transition from low-forcing-amplitude quasiperiodicity to entrainment of the chemostat behavior by strong forcing (involving the concerted closing of resonance horns) is analyzed. We concentrate on certain strong resonance phenomena between the two frequencies and provide an extensive atlas of computed phase portraits for our model system. Our observations corroborate recent mathematical results and case studies of periodically forced chemical oscillators. In particular, the existence and relative succession of several distinct types of global bifurcations resulting in chaotic transients and multistability are studied in detail. The location in the operating diagram of several key codimension 2 local bifurcations of periodic solutions is computed, and their interaction with an interesting feature we name "real-eigenvalues horns" is examined.

Animals↗

PubMedDate not supplied

External collaboration and performance: North Carolina local public health departments, 1996.

OBJECTIVES: This study examined the extent to which local public health departments in North Carolina collaborated with other groups and organizations, the health problems on which they worked together, and the effect of external collaboration on health departments' performance on core public health functions. METHODS: The author mailed a questionnaire asking about interactions with city and county government agencies, boards of health, schools, nonprofits, physicians/private clinics, community health centers/migrant clinics, community members, citizens' groups, state and federal agencies, and universities to all of the directors of local public health departments in North Carolina. Sixty-four directors returned the questionnaire, for a response rate of 74.4%. RESULTS: Local public health departments most frequently interacted with boards of health, state agencies, community members, schools, city and county government agencies, and nonprofit agencies. Large majorities reported productive relationships with boards of health, state agencies, city and county government agencies, schools, nonprofit agencies, and hospitals. Greater frequency of interaction with several types of partners was associated with better performance. CONCLUSIONS: While questions exist about whether performance on core functions improves the community's health status, the results suggest that it is important for local public health departments to continue to build relationships with other organizations in the community.

Community-Institutional Relations↗

PubMed1978

Mutagenic interaction between near-(365 nm) and far-(254 nm)ultraviolet radiation in repair-proficient and excision-deficient strains of Escherichia coli.

The mutational interaction between radiation at 365 and 254 nm was studied in various strains of E. coli by a mutant assay based on reversion to amino-acid independence in full nutrient conditions. In the two repair-proficient strains (K12 AB 1157 and B/r), pre-treatment with radiation at 365 nm strongly suppressed the induction of mutations by far-UV, a phenomenon accompanied by a strong lethal interaction. The frequency of mutations induced by far-UV progressively declined with increasing dose of near-UV. Far-UV-induced mutagenesis to T5 resistance was almost unaltered by pre-treatment with near-UV. In AB 1886 uvrA there was no lethal interaction between the two wavelengths but the mutagenic interaction was synergistic. This synergism was maximal at a 365-nm dose of 8 X 10(5) J m-2. It is proposed that in the wild-type strain, cells containing potentially mutagenic lesions are selectively eliminated from the population because of abortive excision of an error-prone repair-inducing signal. In excisionless strains, 365-nm radiation may be less damaging to the error-prone than to the error-free post-replication repair system. Alternatively, mutation may be enhanced because of the occurrence of error-prone repair of 365-nm lesions by a system that is not induced in the absence of 254-nm radiation.

Amino Acids↗

PubMedDate not supplied

Latency of DPOAE in milliseconds and waves.

UNLABELLED: The latency of Distortion Product Otoacoustic Emissions is defined as the time interval between the wave onset from initial stimulation and the return to the ear canal. AIM: The aim of this research was to verify the latency of the distortion product otoacoustic emissions in normal hearing adults, analyzing the influence of the gender, ear, frequencies and measurements. STUDY DESIGN: clinical prospective. MATERIAL AND METHOD: The measurements had been taken in milliseconds and waves. It was an experimental study, conducted at São Paulo City in 2003. The sample consisted of 38 adults, 18 men and 20 women. Significant Differences for interactions between frequency, ear, gender and measurements were not observed in relation to the latency in milliseconds and waves. A high correlation between the latency measurements in milliseconds and waves was observed. It was concluded that the latency of distortion product otoacoustic emission diminishes as increases the frequency in milliseconds and the opposite occurs in waves. Statistical differences in latencies of distortion product otoacoustic emission were not observed between gender, ears and measurements.

Acoustic Impedance Tests↗

PubMed2004

Agonistic behavior and dominance relationships in female Phayre's leaf monkeys -- preliminary results.

Socioecological theory suggests a link between the strength of competition for food/safety, rates of agonism, structure of dominance hierarchies, and dispersal among group-living females. This study presents preliminary data on agonistic behavior and dominance relationships for female Phayre's leaf monkeys (Trachypithecus phayrei), a species in which females routinely disperse. Behavioral observations were conducted on two groups (four adult females, and five adult females plus two juvenile females, respectively) at Phu Khieo Wildlife Sanctuary, northeast Thailand. Rates of agonistic behavior were analyzed from focal continuous recordings, while dominance hierarchies were constructed from all agonistic behaviors (focal and ad libitum sampling). Overall, female-female agonistic behaviors (aggression, submission, and displacements) occurred at a rate of < 0.25 interactions per hour. Agonistic interactions involving food occurred more frequently than expected based on feeding time. Females in both groups exhibited linear dominance hierarchies with some reversals, and possibly an age-inversed hierarchical structure in the larger group. The results fit well with previous results for colobine monkeys regarding frequency of interactions, displacements predominating agonistic behavior, and the possibility of an age-inversed hierarchy. The results contradict the suggested link between linearity of hierarchies and female philopatry. Future studies should consider the notion that female dispersal may coexist with linear dominance hierarchies.

Age Factors↗

PubMed2006

An electrophysiological study on the interaction between emotional content and spatial frequency of visual stimuli.

Previous studies suggest that the magnocellular pathway, a visual processing system that rapidly provides low spatial frequency information to fast-responding structures such as the amygdala, is more involved in the processing of emotional facial expressions than the parvocellular pathway (which conveys all spatial frequencies). The present experiment explored the spatio-temporal characteristics of the spatial frequency modulation of affect-related neural processing, as well as its generalizability to non-facial stimuli. To that aim, the event-related potentials (ERPs) elicited by low-pass filtered (i.e., high spatial frequencies are eliminated) and intact non-facial emotional images were recorded from 31 participants using a 60-electrode array. The earliest significant effect of spatial frequency was observed at 135 ms from stimulus onset: N135 component of the ERPs. In line with previous studies, the origin of N135 was localized at secondary visual areas for low-pass filtered stimuli and at primary areas for intact stimuli. Importantly, this component showed an interaction between spatial frequency and emotional content: within low-pass filtered pictures, negative stimuli elicited the highest N135 amplitudes. By contrast, within intact stimuli, neutral pictures were those eliciting the highest amplitudes. These results suggest that high spatial frequencies are not essential for the initial affect-related processing of visual stimuli, which would mainly rely on low spatial frequency visual information. According to present data, high spatial frequencies would come into play later on.

Adult↗

PubMed1992

Physiological interaction processes and radio-frequency energy absorption.

Because exposure to microwave fields at the resonant frequency may generate heat deep in the body, hyperthermia may result. This problem has been examined in an animal model to determine both the thresholds for response change and the steady-state thermoregulatory compensation for body heating during exposure at resonant (450 MHz) and supra-resonant (2,450 MHz) frequencies. Adult male squirrel monkeys, held in the far field of an antenna within an anechoic chamber, were exposed (10 min or 90 min) to either 450-MHz or 2,450-MHz CW fields (E polarization) in cool environments. Whole-body SARs ranged from 0-6 W/kg (450 MHz) and 0-9 W/kg (2,450 MHz). Colonic and several skin temperatures, metabolic heat production, and evaporative heat loss were monitored continuously. During brief RF exposures in the cold, the reduction of metabolic heat production was directly proportional to the SAR, but 2,450-MHz energy was a more efficient stimulus than was the resonant frequency. In the steady state, a regulated increase in deep body temperature accompanied exposure at resonance, not unlike that which occurs during exercise. Detailed analyses of the data indicate that temperature changes in the skin are the primary source of the neural signal for a change in physiological interaction processes during RF exposure in the cold.

Animals↗

PubMed2005

Reciprocal interactions between oscillatory activities of different frequencies in the subthalamic region of patients with Parkinson's disease.

Synchronization of neuronal activity evident in the local field potential (LFP) recorded in the subthalamic region of patients with Parkinson's disease occurs at low frequencies (< 30 Hz) and, in some patients following treatment with levodopa, at high frequencies between 65 and 85 Hz. Here we investigate the functional relationship between these different activities by determining whether spontaneous fluctuations in their strength are correlated across time. To this end, we analysed recordings of LFPs from macroelectrodes inserted in the subthalamic area of 16 patients with Parkinson's disease, after treatment with anti-parkinsonian medication. Time-evolving autospectra of LFPs with significant 65-85 Hz peaks (from 21 sides) were computed and correlations between frequency components determined over time. LFP activity in the 5-32 Hz band was significantly negatively correlated with that in the 65-85 Hz band in data averaged across all 21 sides, as well as in 15 (71%) of the individual records. Negative correlations were relatively selective for interactions between these frequency bands and occurred over time epochs of as little as 40 s. They occurred about 50 min after levodopa and were recorded concurrently with contralateral levodopa-induced dyskinesias in all but four cases. Positive correlations were not seen between activities in the 5-32 Hz and 65-85 Hz bands. The spontaneous negative correlations suggest a reciprocal relationship between population synchrony in the high- and low-frequency ranges, and raise the possibility that spontaneous fluctuations in the balance between these activities may contribute to levodopa-induced dyskinesias.

Action Potentials↗