Capsaicin increases modulation of sympathetic nerve activity in rats: measurement using power spectral analysis of heart rate fluctuations

We assessed the sympatho-vagal activities of the heart after administration of capsaicin by measuring the power spectral analysis in rats. There were major two frequency components of heart rate variability, which we defined as high (1.0 Hz <, HF) and low (LF, < 1.0 Hz) frequency components. Vagal blockade by atropine abolished the high frequency component, and lowered the amplitude of the low frequency component. On the other hand, under conditions of sympathetic blockade by propranolol, the low frequency component was reduced. Combined vagal and sympathetic blockade abolished all heart rate fluctuations. We analyzed the low and high frequency components by integrating the spectrum for the respective band width. The rats administered capsaicin had a higher heart rate and sympathetic nervous system index (LF/HF) than the control group of rats. These results suggest that power spectral analysis is an effective and noninvasive method for detecting subtle changes in autonomic activity in response to the intake of foods or drugs.     

Noise-Induced Frequency Modifications of Tamarin Vocalizations: Implications for Noise Compensation in Nonhuman Primates

Previous research suggests that nonhuman primates have limited flexibility in the frequency content of their vocalizations, particularly when compared to human speech. Consistent with this notion, several nonhuman primate species have demonstrated noise-induced changes in call amplitude and duration, with no evidence of changes to spectral content. This experiment used broad- and narrow-band noise playbacks to investigate the vocal control of two call types produced by cotton-top tamarins (Saguinus Oedipus). In ‘combination long calls’ (CLCs), peak fundamental frequency and the distribution of energy between low and high frequency harmonics (spectral tilt) changed in response to increased noise amplitude and bandwidth. In chirps, peak and maximum components of the fundamental frequency increased with increasing noise level, with no changes to spectral tilt. Other modifications included the Lombard effect and increases in chirp duration. These results provide the first evidence for noise-induced frequency changes in nonhuman primate vocalizations and suggest that future investigations of vocal plasticity in primates should include spectral parameters.     

Low Light Adaptation: Energy Transfer Processes in Different Types of Light Harvesting Complexes from Rhodopseudomonas palustris

Energy transfer processes in photosynthetic light harvesting 2 (LH2) complexes isolated from purple bacterium Rhodopseudomonas palustris grown at different light intensities were studied by ground state and transient absorption spectroscopy. The decomposition of ground state absorption spectra shows contributions from B800 and B850 bacteriochlorophyll (BChl) a rings, the latter component splitting into a low energy and a high energy band in samples grown under low light (LL) conditions. A spectral analysis reveals strong inhomogeneity of the B850 excitons in the LL samples that is well reproduced by an exponential-type distribution. Transient spectra show a bleach of both the low energy and high energy bands, together with the respective blue-shifted exciton-to-biexciton transitions. The different spectral evolutions were analyzed by a global fitting procedure. Energy transfer from B800 to B850 occurs in a mono-exponential process and the rate of this process is only slightly reduced in LL compared to high light samples. In LL samples, spectral relaxation of the B850 exciton follows strongly nonexponential kinetics that can be described by a reduction of the bleach of the high energy excitonic component and a red-shift of the low energetic one. We explain these spectral changes by picosecond exciton relaxation caused by a small coupling parameter of the excitonic splitting of the BChl a molecules to the surrounding bath. The splitting of exciton energy into two excitonic bands in LL complex is most probably caused by heterogenous composition of LH2 apoproteins that gives some of the BChls in the B850 ring B820-like site energies, and causes a disorder in LH2 structure.     

Walking in Fourier’s space: algorithms for the computation of periodicities in song patterns by the cricket Gryllus bimaculatus

Is discrimination of the envelope of an acoustic signal based on spectral or temporal computations? To investigate this question for the cricket Gryllus bimaculatus, pattern envelopes were constructed by the addition of several sine waves and modified by systematic phase changes. The phonotactic response of female crickets towards such sinusoidal but also rectangular pulse patterns was quantified on a locomotion compensator. Envelope patterns that exhibited a modulation frequency of 25 Hz as the dominant frequency were attractive and although changes of phase modified the temporal pattern, the values of attractiveness remained unaffected. Removal of the 25-Hz component reduced the phonotactic scores. Patterns in which other frequency components exhibited a larger amplitude than the 25-Hz component were less attractive. However, the combination of an unattractive pulse period with the attractive modulation frequency of 25 Hz in a pattern revealed that such stimuli were unattractive despite the presence of the 25-Hz component. A comparison of the attractiveness of all patterns revealed that female crickets evaluated the duration of pulse period over a wide range of duty cycles. The combined evidence showed that pattern envelopes were processed in the time- and not in the spectral domain.     

Photosynthetic responses of leaves to water stress, expressed by photoacoustics and related methods : I. Probing the photoacoustic method as an indicator for water stress in vivo

The effect of leaf desiccation on the photosynthetic activities in vivo was probed by the photoacoustic method. The aim of this research was: (a) To study the photoacoustic signal per se in varied conditions in order to develop this tool as a probe for stress conditions in vivo. (b) To obtain results pertaining to electron transport activities in vivo, and confirm conclusions based on work with isolated chloroplasts, which could otherwise be the result of nonspecific damage occurring during their isolation. Leaf discs from tobacco (Nicotiana tabacum L.) were routinely used, with other species tested also for comparison. Rapid leaf desiccation caused changes in the low frequency photoacoustic signal, attributed both to the mechanism of signal transduction, influenced by changes in the structural parameters of the leaf, and to the direct (nonstomatal) inhibition of gross photosynthesis. The dependence of the photothermal part of the signal on the frequency indicated the presence of two photothermal components, one of which persisted only at low modulation frequencies (below about 100 Hz) and which largely increased with the desiccation treatment. This component was ascribed to a thermal wave which reaches the leaf surface. The other nonvariable photothermal component was ascribed to a thermal wave propagating from the chloroplasts to the surface of the mesophyll cell. Only this component is considered in the ratio of the O₂ signal to the photothermal signal, which is used to estimate the quantum yield of photosynthesis. The specific dependence of the latter ratio on the frequency yielded a comparative quantum yield parameter from its extrapolation to zero frequency, and also indicated stress induced changes in the diffusion of O₂ through the mesophyll cell, reflected by changes in its characteristic slope. The (zero frequency extrapolated) quantum yield was markedly reduced with the progression of the water stress, indicating the inhibition of (gross) phototosynthetic electron transport in vivo. This result was expressed even more emphatically by the stronger inhibition of the photochemical energy storage, obtained by photoacoustic measurements at a high modulation frequency.     

The Modulation Transfer Function for Speech Intelligibility

We systematically determined which spectrotemporal modulations in speech are necessary for comprehension by human listeners. Speech comprehension has been shown to be robust to spectral and temporal degradations, but the specific relevance of particular degradations is arguable due to the complexity of the joint spectral and temporal information in the speech signal. We applied a novel modulation filtering technique to recorded sentences to restrict acoustic information quantitatively and to obtain a joint spectrotemporal modulation transfer function for speech comprehension, the speech MTF. For American English, the speech MTF showed the criticality of low modulation frequencies in both time and frequency. Comprehension was significantly impaired when temporal modulations <12 Hz or spectral modulations <4 cycles/kHz were removed. More specifically, the MTF was bandpass in temporal modulations and low-pass in spectral modulations: temporal modulations from 1 to 7 Hz and spectral modulations <1 cycles/kHz were the most important. We evaluated the importance of spectrotemporal modulations for vocal gender identification and found a different region of interest: removing spectral modulations between 3 and 7 cycles/kHz significantly increases gender misidentifications of female speakers. The determination of the speech MTF furnishes an additional method for producing speech signals with reduced bandwidth but high intelligibility. Such compression could be used for audio applications such as file compression or noise removal and for clinical applications such as signal processing for cochlear implants.     

Relationship between skin temperature and muscle activation during incremental cycle exercise

While different studies showed that better fitness level adds to the efficiency of the thermoregulatory system, the relationship between muscular effort and skin temperature is still unknown. Therefore, the present study assessed the relationship between neuromuscular activation and skin temperature during cycle exercise. Ten physically active participants performed an incremental workload cycling test to exhaustion while neuromuscular activations were recorded (via surface electromyography – EMG) from rectus femoris, vastus lateralis, biceps femoris and gastrocnemius medialis. Thermographic images were recorded before, immediately after and 10 min after finishing the cycling test, at four body regions of interest corresponding to the muscles where neuromuscular activations were monitored. Frequency band analysis was conducted to assess spectral properties of EMG signals in order to infer on priority in recruitment of motor units. Significant inverse relationship between changes in skin temperature and changes in overall neuromuscular activation for vastus lateralis was observed (r<−0.5 and p<0.04). Significant positive relationship was observed between skin temperature and low frequency components of neuromuscular activation from vastus lateralis (r>0.7 and p<0.01). Participants with larger overall activation and reduced low frequency component for vastus lateralis activation presented a better adaptive response of their thermoregulatory system by showing fewer changes in skin temperature after incremental cycling test.     

Spectral and thermodynamic properties of methanobactin from γ-proteobacterial methane oxidizing bacteria: A case for copper competition on a molecular level

Methanobactin (mb) is a low molecular mass copper-binding molecule analogous to iron-binding siderophores. The molecule is produced by many methanotrophic or methane oxidizing bacteria (MOB), but has only been characterized to date in one MOB, Methylosinus trichosporium OB3b. To explore the potential molecular diversity in this novel class of metal binding compound, the spectral (UV-visible, fluorescent, and electron paramagnetic resonance) and thermodynamic properties of mb from two γ-proteobacterial MOB, Methylococcus capsulatus Bath and Methylomicrobium album BG8, were determined and compared to the mb from the α-proteobacterial MOB, M. trichosporium OB3b. The mb from both γ-proteobacterial MOB differed from the mb from M. trichosporium OB3b in molecular mass and spectral properties. Compared to mb from M. trichosporium OB3b, the extracellular concentrations were low, as were copper-binding constants of mb from both γ-proteobacterial MOB. In addition, the mb from M. trichosporium OB3b removed Cu(I) from the mb of both γ-proteobacterial MOB. Taken together the results suggest mb may be a factor in regulating methanotrophic community structure in copper-limited environments.     

The resistance mechanism of the Asian honey bee,Apis cerana Fabr., to an ectoparasitic mite,Varroa jacobsoni Oudemans

A behavioral and physiological resistance mechanism of the Asian honey bee (Apis cerana) to an ectoparasitic mite, Varroa jacobsoni, which causes severe damage to the European honey bee (Apis mellifera) in the beekeeping industry worldwide, is reported here for the first time. Parasitism by the mite induced Asian worker bees to perform a series of cleaning behaviors that effectively removed the mites from the bodies of the adult host bees. The mites were subsequently killed and removed from the bee hives in a few seconds to a few minutes. The grooming behavior consists of self-cleaning, grooming dance, nestmate cleaning, and group cleaning. Worker bees can also rapidly and effectively remove the mites from the brood. The European bee showed cleaning behavior at low frequency and generally failed to remove the mites from both the adult bees and the brood.     

THE ELECTRIC RESISTANCE AND CAPACITY OF BLOOD FOR FREQUENCIES BETWEEN 800 AND 4? MILLION CYCLES

1. The variation of the experimental values (R (ω)), (C (ω)) of the resistance and capacity of blood for increasing frequencies is approximately represented by the equation: See PDF for Equation in which R _o and C _o are the resistance and capacity of the blood at low frequency and See PDF for Equation is the resistance of the blood at infinite frequency. Formulæ (1) and (2) are derived by considering the blood as equivalent to the system shown in the diagram (a) of Fig. 1. 2. By the application of formula (1) to our experimental data the value of R(∞) can be extrapolated with high accuracy. R(∞) represents the resistance) which would have been obtained at low frequency, if the membranes around the corpuscles could have been removed. 3. The specific resistance of the corpuscle interior can be calculated by equation (5), using experimental values for R(∞), for the volume concentration of the blood and for the specific resistance of the serum. 4. The specific resistance of the interior of the red corpuscle of the calf is found to be 3.5 ± 10 per cent times the specific resistance of the serum.     

Hydroxylamine-O-sulfonic acid: in vitro and possible in vivo reaction with DNA

Exposure of DNA solutions to low levels (2 · 10^?3M) of hydroxylamine-O-sulfonic acid (HOS) resulted in limited degradation accompanied by increases in the buoyant density of the DNA. The thermal helix-coil profile of the DNA was not changed significantly following exposure to HOS. Upon thermal denaturation, the treated DNA specimens exhibited buoyant density values similar to those of heated control DNA. This is taken to mean that an added function or a modified DNA base is removed upon heating. Exposure of DNA to elevated levels of HOS (>0.2 M) resulted in extensive degradation which was accompanied by spectral changes: a hyperchromic shift and an increase in the wavelength of maximum absorbance.Exposure of individual deoxynucleosides to HOS also resulted in spectral changes and in the detection of new reaction products by paper Chromatographic means.HOS preferentially inhibited the growth of a bacterial strain deficient in DNA polymerase. This is a property also exhibited by known mutagens and carcinogens. This is taken to mean that HOS is capable of reacting with the DNA of living cells as well.     

Capsaicin Increases Modulation of Sympathetic Nerve Activity in Rats: Measurement Using Power Spectral Analysis of Heart Rate Fluctuations

We assessed the sympatho-vagal activities of the heart after administration of capsaicin by measuring the power spectral analysis in rats. There were major two frequency components of heart rate variability, which we defined as high (1.0 Hz<, HF) and low (LF, <1.0 Hz) frequency components. Vagal blockade by atropine abolished the high frequency component, and lowered the amplitude of the low frequency component. On the other hand, under conditions of sympathetic blockade by propranolol, the low frequency component was reduced. Combined vagal and sympathetic blockade abolished all heart rate fluctuations. We analyzed the low and high frequency components by integrating the spectrum for the respective band width. The rats administered capsaicin had a higher heart rate and sympathetic nervous system index (LF/HF) than the control group of rats. These results suggest that power spectral analysis is an effective and noninvasive method for detecting subtle changes in autonomic activity in response to the intake of foods or drugs.     

Protective effect of extracellular protein metabolite of <Emphasis Type="Italic">Luteococcus japonicus</Emphasis> subsp. <Emphasis Type="Italic">casei</Emphasis> on cells subjected to heating and UV irradiation

Extracellular protein metabolite isolated from the culture liquid of Luteococcus japonicus subsp. casei had reactivating and protective effects on UV-irradiated and heated cells. The extracellular metabolite, produced by cells in the logarithmic growth phase, was present in culture liquid in minuscule amounts. Mass spectral analysis showed that, along with the major component with a molecular weight of 7.6 kDa, the preparation contained low quantities of three minor proteins. Apparently, the biological activity of the exometabolite is determined by the major polypeptide component.     

Fast Electrical Potential from a Long-Lived,Long-Wavelength Photoproduct of Fly Visual Pigment

A rapid electrical potential, which we have named the M-potential, can be obtained from the Drosophila eye using a high energy flash stimulus. The potential can be elicited from the normal fly, but it is especially prominent in the mutant norp A^P12 (a phototransduction mutant), particularly if the eye color pigments are genetically removed from the eye. Several lines of evidence suggest that the M-potential arises from photoexcitation of long-lived metarhodopsin. Photoexcitation of rhodopsin does not produce a comparable potential. The spectral sensitivity of the M-potential peaks at about 575 nm. The M-potential pigment (metarhodopsin) can be shown to photoconvert back and forth with a "silent pigment(s)" absorbing maximally at about 485 nm. The silent pigment presumably is rhodopsin. These results support the recent spectrophotometric findings that dipteran metarhodopsin absorbs at much longer wavelengths than rhodopsin. The M-potential probably is related to the photoproduct component of the early receptor potential (ERP). Two major differences between the M-potential and the classical ERP are: (a) Drosophila rhodopsin does not produce a rapid photoresponse, and (b) an anesthetized or freshly sacrificed animal does not yield the M-potential. As in the case of the ERP, the M-potential appears to be a response associated with a particular state of the fly visual pigment. Therefore, it should be useful in in vivo investigations of the fly visual pigment, about which little is known.     

Metabolic profiling of a Schistosoma mansoni infection in mouse tissues using magic angle spinning-nuclear magnetic resonance spectroscopy

In order to enhance our understanding of physiological and pathological consequences of a patent Schistosoma mansoni infection in the mouse, we examined the metabolic responses of different tissue samples recovered from the host animal using a metabolic profiling strategy. Ten female NMRI mice were infected with ∼80 S. mansoni cercariae each, and 10 uninfected age- and sex-matched animals served as controls. At day 74 post infection (p.i.), mice were killed and jejunum, ileum, colon, liver, spleen and kidney samples were removed. We employed ¹H magic angle spinning-nuclear magnetic resonance spectroscopy to generate tissue-specific metabolic profiles. The spectral data were analyzed using multivariate modelling methods including an orthogonal signal corrected-projection to latent structure analysis and hierarchical principal component analysis to assess the differences and/or similarities in metabolic responses between infected and non-infected control mice. Most tissues obtained from S. mansoni-infected mice were characterized by high levels of amino acids, such as leucine, isoleucine, lysine, glutamine and asparagine. High levels of membrane phospholipid metabolites, including glycerophosphoryl choline and phosphoryl choline were found in the ileum, colon, liver and spleen of infected mice. Additionally, low levels of energy-related metabolites, including lipids, glucose and glycogen were observed in ileum, spleen and liver samples of infected mice. Energy-related metabolites in the jejunum, liver and renal medulla were found to be positively correlated with S. mansoni worm burden upon dissection. These findings show that a patent S. mansoni infection causes clear disruption of metabolism in a range of tissues at a molecular level, which can be interpreted in relation to the previously reported signature in a biofluid (i.e. urine), giving further evidence of the global effect of the infection.     

Conventional Frequency Ultrasonic Biomarkers of Cancer Treatment Response In Vivo

BACKGROUND: Conventional frequency quantitative ultrasound in conjunction with textural analysis techniques was investigated to monitor noninvasively the effects of cancer therapies in an in vivo preclinical model. METHODS: Conventional low-frequency (～7 MHz) and high-frequency (～20 MHz) ultrasound was used with spectral analysis, coupled with textural analysis on spectral parametric maps, obtained from xenograft tumor-bearing animals (n = 20) treated with chemotherapy to extract noninvasive biomarkers of treatment response. RESULTS: Results indicated statistically significant differences in quantitative ultrasound-based biomarkers in both low- and high-frequency ranges between untreated and treated tumors 12 to 24 hours after treatment. Results of regression analysis indicated a high level of correlation between quantitative ultrasound-based biomarkers and tumor cell death estimates from histologic analysis. Applying textural characterization to the spectral parametric maps resulted in an even stronger correlation (r² = 0.97). CONCLUSION: The results obtained in this research demonstrate that quantitative ultrasound at a clinically relevant frequency can monitor tissue changes in vivo in response to cancer treatment administration. Using higher order textural information extracted from quantitative ultrasound spectral parametric maps provides more information at a high sensitivity related to tumor cell death.     

A new method for estimating voice sounds transmitted to the chest wall in children and adolescents

A new method for estimating voice sound transmission to the chest wall is proposed. The spectral characteristics of voice-transmitted sounds have been estimated in children and adolescents. A total of 37 subjects aged 7–17 yers were examined. The frequency of the first spectral peak of the voice-transmitted sounds “tree, tree” (M ± SD) is 263.7 ± 7.82 and 253 ± 4.29 Hz at ages of 7–11 and 12–14 years, respectively. In male adolescents aged 15–17 years, this frequency is decreased to 100–150 Hz. The slope of the descending segment of the spectrum on the high-frequency side of the peak steadily increases on moving from the upper to the lower zones of the lungs, which may be related to the increase in the air content of the lung tissue. The difference between the amplitudes of the first and second spectral peaks of voice-transmitted sounds over symmetric regions of the chest on the right and left sides (Me(Q75-Q25)) is ?0.1(11.0) dB and does not depend on age or sex, which can be interpreted as an average statistical symmetry of sound transmission.     

Analysis of signal components < 500 Hz in brain organoids coupled to microelectrode arrays: A reliable test-bed for preclinical seizure liability assessment of drugs and screening of antiepileptic drugs

Brain organoids with three-dimensional structure and tissue-like function are highly demanded for brain disease research and drug evaluation. However, to our knowledge, methods for measuring and analyzing brain organoid function have not been developed yet. This study focused on the frequency components of an obtained waveform below 500 Hz using planner microelectrode array (MEA) and evaluated the response to the convulsants pentylenetetrazol (PTZ) and strychnine as well as the antiepileptic drugs (AEDs) perampanel and phenytoin. Sudden and persistent seizure-like firing was observed with PTZ administration, displaying a concentration-dependent periodic activity with the frequency component enhanced even in one oscillation characteristic. On the other hand, in the administration of AEDs, the frequency of oscillation decreased in a concentration-dependent manner and the intensity of the frequency component in one oscillation also decreased. Interestingly, at low doses of phenytoin, a group of synchronized bursts was formed, which was different from the response to the perampanel. Frequency components contained information on cerebral organoid function, and MEA was proven useful in predicting the seizure liability of drugs and evaluating the effect of AEDs with a different mechanism of action. In addition, frequency component analysis of brain organoids using MEA is an important analysis method to perform in vitro to in vivo extrapolation in the future, which will help explore the function of the organoid itself, study human brain developments, and treat various brain diseases.     

Thermal entrainment methods for studying Raynaud's phenomenon

Entrainment occurs when an externally applied periodic temperature stimulus forces the peripheral bloodflow component of thermoregulation to oscillate at the same frequency. This phenomenon can be demonstrated using frequency transforms to analyse the spectral content of the bloodflow, and can be used as a diagnostic test for Raynaud's phenomenon. Correlations were performed between the clinical diagnosis and the objective tests. The average inter-clinical correlation coefficient was r = 0.66. When the average clinical diagnosis was compared with a combination of thermal entrainment and digital patency testing the correlation coefficient rose to r = 0.68. These results highlight the difficulties encountered when assessing patients with Raynaud's phenomenon and the necessity of applying both physiological and clinical techniques.     

A synchronous peroral technique for the bioassay of insect viruses

A relatively fast and simple peroral technique for the bioassay of insect viruses is described in which newly hatched larvae ingest a uniform volume of virus suspension. Three isolates of the Autographa californica nuclear polyhedrosis virus (NPV) and one isolate of the Heliothis zea NPV were used to test the procedure with Trichoplusia ni and H. zea larvae, respectively. Within-assay and between-assay variation was very low with coefficients of variation averaging 0.012 ± 0.006 and 0.20 ± 0.04 for time-mortality and dose-mortality tests, respectively. The synchronous uptake of virus removed the acquisition-time component of the LT₅₀ values while the constant volume improved the accuracy of LD₅₀ values. The procedure was shown to be suitable for a wide variety of lepidopterous species, including Spodoptera frugiperda, S. eridania, Estigmene acrea, Plutella xylostella, Choristoneura fumiferana, Ostrinia nubilalis, Plodia interpunctella, and Pieris rapae.