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PubMed2000

Auditory cortical responses to the interactive effects of interaural intensity disparities and frequency.

Under natural conditions, stimuli reaching the two ears contain multiple acoustic components. Rarely does a stimulus containing only one component (e.g. pure tone burst) exist outside the realm of the laboratory. For example, in sound localization the simultaneous presence of multiple cues (spectral content, level, phase, etc.) serves to increase the number of available cues and provide the listener with more information, thereby helping to reduce errors in locating the sound source. The present study was designed to explore the relationship between two acoustic parameters: stimulus frequency and interaural intensity disparities (IIDs). By varying both stimulus frequency and IIDs for each cell, we hoped to gain insight into how multiple cues are processed. To this end, we examined the responses of neurons in cat primary auditory cortex (AI) to determine if their sensitivity to IIDs changed as a function of stimulus frequency. IIDs ranging from +30 to -30 dB were presented at different frequencies (frequency was always the same in the two ears). We found that approximately half of the units examined exhibited responses to IIDs that varied as a function of stimulus frequency (i.e. displayed some form of IID x Freq dependency). The remaining units displayed IID responses that were not clearly related to stimulus frequency.

Acoustic Stimulation↗
PubMed1996

Asymmetric interactions between phosphorylation pathways regulating ciliary beat frequency in human nasal respiratory epithelium in vitro.

1. The effects of the sequential stimulation of ciliary beat frequency (CBF) via two different phosphorylation cascades (dependent on protein kinase A (PKA) and calmodulin, respectively) were determined using video microscopy applied to a perfused preparation of human nasal respiratory epithelium in vitro. Dibutyryl cyclic AMP (db-cAMP) (10(-3) M) was used to stimulate PKA and the calcium ionophore 4-Br-A23187 (10(-5) M) was used to stimulate calmodulin-dependent phosphorylation. 2. Perfusion with db-cAMP (10(-3) M) alone showed an early rise in CBF (15.0 +/- 4%, mean +/- S.E.M., P < 0.05) by 10 min which remained elevated for 35 min; in contrast, the highest CBF response to 4-Br-A23187 (10(-5) M) alone was not achieved until 35 min (16.1 +/- 1.8%, P < 0.05). 3. When a db-cAMP stimulus was applied to cells which had been pre-incubated with 4-Br-A23187 for 30 min, a further rise in CBF (maximal at 20 min, 14.3 +/- 2%, P < 0.05) was observed. Reversing the sequence of perfusions, cells pre-incubated with db-cAMP showed no further rise in response to stimulation with 4-Br-A23187. 4. We hypothesized that PKA inhibited the response to the 4-Br-A23187. This notion was supported by the restoration of the CBF response (22.8 +/- 4%, P < 0.05) to 4-Br-A23187 when the cells were pre-incubated with the protein kinase inhibitor 1-(5-isoquinolinyl-sulphonyl)-2-methylpiperazine (10(-3) M), before the sequential perfusions with db-cAMP and 4-Br-A23187. We conclude that the A23187-dependent pathway, which regulates intrinsic CBF, is inhibited by db-cAMP but not vice versa.

Adolescent↗
PubMed1998

EBV-NK cells interactions and lymphoproliferative disorders.

Epstein-Barr virus (EBV) usually infects epithelial cells in the oropharynx and B lymphocytes asymptomatically. Occasionally, however, EBV infects T-cells and natural killer (NK) cells, and infection of these cells has been associated with the development of leukemias and lymphomas. EBV-positive lymphoproliferative disorders of NK cells have been reported with increasing frequency, but the interactions between EBV and NK cells are not fully understood, in part because NK cells are not usually infected with EBV in vitro. The lymphoma-derived EBV-positive NK cell line, YT, has been useful in the study of EBV infection of NK cells. YT cells express the EBV-associated nuclear antigen (EBNA)-1, the latent membrane protein (LMP)-1, and LMP-2A, but not EBNA-2 and LMP-2B genes. This pattern of latent gene expression is compatible with a type II latency program, normally associated with nasopharyngeal carcinoma, Hodgkin's disease, and T-cell lymphoma. In this report, we summarize recent information on EBV-NK cell interactions and EBV-positive lymphoproliferative disorders of NK cells.

B-Lymphocytes↗
PubMed1996

Resonance effect of millimeter waves in the power range from 10(-19) to 3 x 10(-3) W/cm2 on Escherichia coli cells at different concentrations.

The effect of millimeter waves (MMWs) on the genome conformational state (GCS) of E. coli AB1157 cells was studied by the method of anomalous viscosity time dependencies (AVTD) in the frequency range of 51.64-51.85 GHz. The 51.755 GHz resonance frequency of the cell reaction to MMWs did not depend on power density (PD) in the range from 10(-19) to 3 x 10(-3) W/cm2. The half-width of the resonant reaction of cells showed a sigmoid dependence on PD, changing from 3 MHz to 100 MHz. The PD dependence of the half-width had the same shape for different concentrations of exposed cells (4 x 10(7) and 4 x 10(8) cells/ml), whereas the magnitude of the 51.755 GHz resonance effect differed significantly and depended on the PD of MMW exposure. Sharp narrowing of the 51.755 GHz resonance in the PD range from 10(-4) to 10(-7) W/cm2 was followed by an emergence of new resonance frequencies. The PD dependence of the MMW effect at one of these resonance frequencies (51.674 GHz) differed markedly from the corresponding dependence at the 51.755 GHz resonance, the power window occurring in the range from 10(-16) to 10(-8) W/cm2. The results obtained were explained in the framework of a model of electron-conformational interactions. The frequency-time parameters of this model appeared to be in good agreement with experimental data.

Bacterial Proteins↗
PubMed2006

Verbal and social interactions in Swedish forensic psychiatric nursing care as perceived by the patients and nurses.

Patients and nurses in a Swedish forensic psychiatric unit filled in a questionnaire Verbal and Social Interactions designed to survey patients' and nurses' views on the frequency and importance of nursing interactions in forensic psychiatric care. The patients perceived the 'supportive/encouraging interactions' and the 'reality orientation interactions' as the most frequent interactions and the 'supportive/encouraging interactions' and the 'social skills training' as the most important interactions. The nurses perceived the 'supportive/encouraging interactions' and the 'practical skills training' as the most frequent and the 'supportive/encouraging interactions', 'interpretative interactions' and the 'practical skills training' as the most important interactions. There were significant differences between patients' and nurses' perceptions about the frequency of all the different groups of interactions, but greater agreement as to the importance. In general, the patients perceived that the interactions occurred less frequently than the nurses. The differences between patients' and nurses' perceptions on the interactions as well as the clinical implications of these differences are discussed.

Adult↗
PubMed2003

Family history is a coronary heart disease risk factor in the Second Northwick Park Heart Study.

We have estimated the risk of coronary heart disease (CHD) from family history of CHD (FHCHD) in 2827 healthy European middle-aged men, and explored the extent to which this can be explained by classical and genetic risk factors. Men with FHCHD (obtained by questionnaire) had a hazard ratio of CHD of 1.73 (95% confidence interval: 1.30, 2.31) compared to those without FHCHD; after adjusting for classical risk factors this did not change substantially. Those with FHCHD had 2.3% lower Factor VIIc (p = 0.03) and 1.14% higher systolic and 1.21% higher diastolic blood pressure (p = 0.04 and p = 0.02), with evidence of interaction between blood pressure and FHCHD status on risk (p = 0.01). The risk for those with a positive family history who were also current smokers was 3.01 compared to non-smokers without FHCHD, which is greater than the risk posed by smoking or FHCHD alone (1.96 and 2.05 respectively compared to non-smokers without FHCHD), but not significantly different from a multiplicative model (p-value for interaction 0.33). Allele frequencies for 13 candidate gene variants were not significantly different between those with and without FHCHD. In those with FHCHD, current smokers who carried the APOE4 allele (e4+) had a hazard ratio of 5.66 compared to non-smokers who had no FHCHD and were not APOE4+, with a significant interaction between smoking and APOE4 in those with FHCHD p = 0.001. These data demonstrate the complex interaction between genetic and environmental factors in determining CHD risk, and suggest that the causes of the familial clustering of CHD remain largely unexplained.

Adult↗
PubMedDate not supplied

Interactions between rod and L-cone signals in deuteranopes: gains and phases.

The dynamics of interactions between rod and L-cone driven signals were studied psychophysically in two deuteranopic observers. Flicker detection thresholds for different ratios of rod to L-cone modulation were measured at temporal frequencies between 1 and 15 Hz. A model, which assumes that rod and L-cone driven signals are vector added, can describe the threshold data adequately. We found that up to about 8-10 Hz temporal frequency, rod and L-cone signals interact additively, whereas at higher frequencies the interaction is subtractive. Rod and L-cone signal strengths depend similarly on temporal frequency and are maximal between 3 and 5 Hz. The phase difference between rod and L-cone signals increases linearly with temporal frequency, indicating that their responses have a delay difference of about 20 to 30 ms, consistent with involvement of the faster rod pathway. The data would suggest a nearly complete additivity of the rod and cone driven signals when using flashed stimuli. But, literature data showed only partial additivity of the two, suggesting that different postreceptoral mechanisms are involved in the two tasks.

Adult↗
PubMed2002

Potential interactions between herbal medicines and conventional drug therapies used by older adults attending a memory clinic.

OBJECTIVE: Herbal medicines and conventional drug therapies are often taken in combination. The objective of our study was to identify the range of natural health products and conventional drug therapies used by older adults (aged 65 years and over) attending a memory clinic, and to specifically evaluate the frequency of potential interactions between herbal medicines and conventional drug therapies. DESIGN: We interviewed consecutive patients attending the Memory Disorders Clinic at the Baycrest Centre for Geriatric Care, a University of Toronto teaching hospital, between 4 July and 15 August 2000. Patients were asked to bring to their appointment all natural health products (i.e. herbal medicines, vitamins and minerals) and conventional drug therapies (i.e. prescription and over-the-counter) they were currently using. We collected information on current and previously used natural health products and current conventional drug therapies. Patients were classified as having the potential for an interaction if they were using a current herbal medicine in combination with a conventional drug therapy and the interaction had been reported previously in the medical literature. PARTICIPANTS: We interviewed 195 consecutive patients attending the Memory Disorders Clinic at the Baycrest Centre for Geriatric Care, Toronto, Ontario, Canada. RESULTS: Of the 195 patients in our sample, 33 (17%) were 'current users', 19 (10%) were 'past users', and 143 (73%) were 'never users' of herbal medicines. Among the 52 patients who were 'current or past users', the most frequently used herbal medicines were ginkgo (Ginkgo biloba) [39 users], garlic (n = 10), glucosamine sulphate (n = 9) and echinacea (n = 8). Among the 33 patients who were current users, the most commonly used herbal medicines were Ginkgo biloba (n = 22), glucosamine sulphate (n = 8) and garlic (n = 6). Among the 33 current users, we identified 11 potential herb-drug interactions in nine patients. The 11 herb-drug interactions we identified were between ginkgo and aspirin (acetylsalicylic acid) [n = 8], ginkgo and trazodone (n = 1), ginseng and amlodipine (n = 1) and valerian and lorazepam (n = 1). CONCLUSIONS: Herbal medicines are widely used. Almost one-third of current users of herbal medicines were at risk of a herb-drug interaction. The most common potential herb-drug interaction was between ginkgo and aspirin. This finding has important potential implications because both of these products are regularly used by older people. Physicians and other healthcare providers should be aware of potential herb-drug interactions and should monitor and inform their patients accordingly.

Aged↗
PubMed2001

Measuring the genetic influence in modulating the human life span: gene-environment interaction and the sex-specific genetic effect.

New approaches are needed to explore the different ways in which genes affect the human life span. One needs to assess the genetic effects themselves, as well as gene-environment interactions and sex dependency. In this paper, we present a new model that combines both genotypic and demographic information in the estimation of the genetic influence on life spans. Based on Cox's proportional hazard assumption, the model measures the risks for each gene as well as for gene-environment and gene-sex interactions, while controlling for confounding factors. A two-step MLE is introduced to obtain a non-parametric form of the baseline hazard function. The model is applied to genotypic data from Italian centenarian studies to estimate relative risks of candidate genes, risks due to interactions and initial frequencies of different genes in the population. Results from models that either do or do not take into consideration individual heterogeneity are compared. It is shown that ignoring the existence of heterogeneity can lead to a systematic underestimation of genetic effects and effects due to interactions.

Alleles↗
PubMed2001

Multiple nonlinear optical interactions with arbitrary wave vector differences.

We present a novel method for simultaneously phase matching several nonlinear optical interactions within a single crystal. Quasiperiodic modulation of the nonlinear coefficient enables one to achieve high frequency mixing efficiencies for interactions with arbitrary wave vector differences. Doubling of two different frequencies as well as direct frequency tripling is experimentally demonstrated. The temperature- and wavelength-dependent properties of these interactions are explored. We discover that periodic approximation to the quasiperiodic structure shifts the phase-matched wavelengths.

Journal Article↗
PubMedDate not supplied

Healing of chronic arterial and venous leg ulcers through systemic effects of electromagnetic fields [corrected].

BACKGROUND: Mitogen-activated autologous peripheral blood mononuclear cells applied locally on the ulcer surface promote healing of chronic arterial and venous leg ulcers. In vitro, extremely low frequency electromagnetic fields (ELF) interact with peripheral blood mononuclear cells (PBMC) via Ca++ channels, activating signal transduction cascades, promoting cytokine synthesis, and changing cell proliferation patterns. METHODS: ELF frequencies were configured to interact in vitro with the proliferation patterns of PBMC obtained from normal human volunteers. These ELF were then applied peripherally as the sole treatment to 26 patients with 42 chronic leg ulcers of predominantly arterial or venous etiology unresponsive to previous medical and/or surgical treatments in a phase I before-after design. RESULTS: At admission, age of ulcers had a skewed distribution with a median of 639 days. Wound healing or deleterious effects began in all patients during the first 2 weeks after ELF exposure, permitting their previously unresponsive ulcers to function as internal controls. After ELF exposure, 69% of all lesions were cured or healed >50% in a period <4 months. Defective wound healing was observed in lesions associated with important arterial occlusion, uncontrolled arterial hypertension, severe lipodermatosclerosis, non-pitting edema, and obesity (body mass index >30). Lesions worsened in patients with autoimmune diseases. CONCLUSIONS: Systemic effects are hypothetically explained by ELF activation of PBMC and their subsequent transportation to the ulcer site via humoral route. This therapy is effective in selected patients with chronic arterial and venous leg ulcers.

Arteries↗
PubMed2003

Technical variability of the RT3 accelerometer.

PURPOSE: To evaluate the technical performance of the RT3 triaxial accelerometer. METHODS: Twenty-three RT3 accelerometers were subjected to a specific vibration along each sensitive axis in isolation, using a motorized vibration table that produced frequencies of 2.1, 5.1, and 10.2 Hz, respectively. Data were analyzed for frequency and axis effects and inter- and intra-instrument variability. RESULTS: ANOVA showed a frequency by axis interaction (F2.1,36.8 = 19.9, P < 0.001). Post hoc tests revealed the Y axis count to be significantly higher than the X and Z axes counts at 5.1 and 10.2 Hz. There was no difference in counts between axes at 2.1 Hz. Interinstrument coefficients of variation (CV) decreased as frequency increased (21.9 to 26.7% at 2.1 Hz, 6.3 to 9.0% at 5.1 Hz, and 4.2 to 7.2% at 10.2 Hz). The intraclass correlation (ICC) between RT3s was 0.99, regardless of the axis. Intra-instrument CV also decreased as frequency increased (2.1 to 56.2%, 0.3 to 2.5%, and 0.2 to 2.9% at 2.1, 5.1, and 10.2 Hz, respectively. CONCLUSION: There were no differences in counts recorded on the X, Y, and Z axes at 2.1 Hz; however, the counts recorded along the Y axis were significantly higher than the counts at the X and Z axes at 5.1 and 10.2 Hz. Due to large coefficients of variation for both inter- and intra-instrument variability at 2.1 Hz, testing the inter- and intra-instrument variability of the accelerometers before use is recommended.

Acceleration↗
PubMed2003

Sex differences in interest in infants in juvenile rhesus monkeys: relationship to prenatal androgen.

Yearling rhesus monkey females interact more with infants than do males. However, the continuity of this sex difference throughout the juvenile period is unknown. Human females display similar sexually differentiated interest in infants, and studies of girls with congenital adrenal hyperplasia suggest that this sex difference may be modulated by prenatal androgen exposure. We investigated infant interest in 1- to 3-year-old juvenile rhesus monkeys. Hormonal influences on this behavior were investigated by treating pregnant females with an androgen-receptor blocker (flutamide), testosterone enanthate, or vehicle, early or late in gestation. Subjects were reared in their well-established natal groups, composed of species-typical matrilineal social structures, including members of all ages. Yearling control females interacted with infants more than did yearling control males. At 2 and 3 years of age, the magnitude of the sex difference in interactions with infants increased markedly, producing effect sizes of more than 2.5 standard deviations. These effects are larger than those reported in humans. Androgen treatment did not affect male or female interactions with infants, but late gestation flutamide masculinized aspects of females' interest in infants. Although early flutamide prevented complete masculinization of male genitalia, this treatment was not accompanied by any alterations in the masculine pattern of infant interest. We found no evidence that the robust juvenile sex difference in frequency of infant interactions results from socialization. However, it was largely unaffected by our hormone manipulations. Whether this reflects characteristics of our specific treatments or is evidence of nonhormonal influences on infant interest remains unanswered.

Age Factors↗
PubMed1996

New drugs for the treatment of epilepsy.

OBJECTIVES: This article will review current data on the metabolism, interactions, methods of analysis, and adverse effects observed with the use of new anticonvulsant drugs. The role of the laboratory in the provision of therapeutic drug monitoring for these drugs is discussed. CONCLUSION: Certain of the newer anticonvulsant drugs require therapeutic drug monitoring for their optimal use in the treatment of epileptic seizures. The requirement for therapeutic drug monitoring has not been established for some of these drugs. Many of the newer anticonvulsant drugs, including lamotrigine, felbamate, vigabatrin, and zonisamide, interact clinically with established drugs, such as phenytoin, phenobarbital, carbamazepine, and valproic acid. Introduction of these new drugs will result in the need for more frequent monitoring of the established drugs during polytherapy. The need for a drug-monitoring service for anticonvulsant drugs overall will continue, due to the frequency of drug interactions, the incidence of adverse effects, and concerns about compliance with the dosing regimen in these patients.

Adult↗
PubMed2007

Lexical restructuring in the absence of literacy.

Vocabulary growth was suggested to prompt the implementation of increasingly finer-grained lexical representations of spoken words in children (e.g., [Metsala, J. L., & Walley, A. C. (1998). Spoken vocabulary growth and the segmental restructuring of lexical representations: precursors to phonemic awareness and early reading ability. In J. L. Metsala & L. C. Ehri (Eds.), Word recognition in beginning literacy (pp. 89-120). Hillsdale, NJ: Erlbaum.]). Although literacy was not explicitly mentioned in this lexical restructuring hypothesis, the process of learning to read and spell might also have a significant impact on the specification of lexical representations (e.g., [Carroll, J. M., & Snowling, M. J. (2001). The effects of global similarity between stimuli on children's judgments of rime and alliteration. Applied Psycholinguistics, 22, 327-342.]; [Goswami, U. (2000). Phonological representations, reading development and dyslexia: Towards a cross-linguistic theoretical framework. Dyslexia, 6, 133-151.]). This is what we checked in the present study. We manipulated word frequency and neighborhood density in a gating task (Experiment 1) and a word-identification-in-noise task (Experiment 2) presented to Portuguese literate and illiterate adults. Ex-illiterates were also tested in Experiment 2 in order to disentangle the effects of vocabulary size and literacy. There was an interaction between word frequency and neighborhood density, which was similar in the three groups. These did not differ even for the words that are supposed to undergo lexical restructuring the latest (low frequency words from sparse neighborhoods). Thus, segmental lexical representations seem to develop independently of literacy. While segmental restructuring is not affected by literacy, it constrains the development of phoneme awareness as shown by the fact that, in Experiment 3, neighborhood density modulated the phoneme deletion performance of both illiterates and ex-illiterates.

Adolescent↗