Simultaneous Recording Of Changes Research Articles

Optimization of the deposition conditions for Ni(OH)2 films for electrochromic elements of “smart” windows

Thestudywasconductedinordertodeterminethe influenceoftwofactorsonelectrodepositionofNi(OH)2 films: concentrationofnickelnitratein the electrolyteanddrying stage between deposition and electrochemical and optical tests. For deposition, pure solutions of nickel nitrate without additives were used, so that the presence of the latter did not complicate the analysis of the data obtained.As a result, two series of films were prepared from electrolytes with nickel nitrate concentrations of 0.01, 0.1 and 1 M. The difference between the two series is the presence or absence of drying stage after deposition. Drying was conducted under mild conditions at room temperatures.Electrochemical and optical characteristics were evaluated by means of cyclic voltamperometry with simultaneous recording of changes in film transparency.As a result of analysis of the obtained data, it was found that uniform films with roughly equal thickness are obtained within the nickel nitrate concentration range from 0.01 to 0.1 M. For solutions with the nickel nitrate concentration of 1 М, deposition occurs with significant non-uniformity. A hypothesis was proposed, in which such behavior is explained by redistribution of current density over the electrode surface due to the high conductivity of the concentrated nickel nitrate solution. In turn, the redistribution of current density results in a significantly high current density on the electrode surface near the electrolyte-air boundary. Such an increase could result in shifting of the reaction front away from the electrode or formation of Ni(OH)2 with high thickness. The latter would lose contact with the electrode and fall off.It was also found that drying process has a significant effect on the structure and properties of the films. Drying process was also found to impact the appearance of nickel hydroxide films due to film cracking. It was also assumed that electrochemically deposited nickel hydroxide contains a large amount of crystal water

A pilot study with simultaneous recording of changes in motility and cortical electrical activity of rats during four weeks of oral manganese exposure

Manganese as an environmental neurotoxicant can cause oral exposure. Six rats were equipped with a connector “crown”, allowing repeated recording of electrocorticogram (ECoG) with simultaneous recording of motor activity in an open field box. Weekly one 30-min recording session was held, and after two control sessions, four of the six rats had 2.5 mg/ml manganese chloride in their drinking water. The treated rats showed higher motility during the exposure period than the untreated ones; and substantially decreased total ECoG power without marked change the spectrum. The changes of both motility and ECoG were correlated to the individual brain Mn levels, and the activity decrease during a session was correlated to the total ECoG power. These effects can be likened to early adult manganism and to symptoms of children exposed to Mn via drinking water. Repeated simultaneous recording of open field motility and spontaneous cortical activity seems suitable to detect early electrophysiological and behavioral effects of an oral neurotoxic exposure.

In Situ Mitochondrial Ca2+ Buffering Differences of Intact Neurons and Astrocytes from Cortex and Striatum

The striatum is particularly vulnerable to neurological disorders, such as Huntington disease. Previous studies, with nonsynaptic mitochondria isolated from cortical and striatal homogenates, suggest that striatal mitochondria are highly vulnerable to Ca(2+) loads, possibly influencing striatal vulnerability. However, whether and how neuronal and glial mitochondria from cortex and striatum differ in Ca(2+) vulnerability remains unknown. We test this hypothesis using a novel strategy allowing comparisons of mitochondrial Ca(2+) buffering capacity in cortical and striatal neuron-astrocyte co-cultures. We provide original evidence that mitochondria not only in neurons but also in astrocytes from striatal origin exhibit a decreased Ca(2+) buffering capacity when compared with cortical counterparts. The decreased mitochondrial Ca(2+) buffering capacity in striatal versus cortical astrocytes does not stem from variation in mitochondrial concentration or in the rate of intracellular Ca(2+) elevation, being mechanistically linked to an increased propensity to undergo cyclosporin A (CsA)-sensitive permeability transition. Indeed, 1 microm CsA selectively increased the mitochondrial Ca(2+) buffering capacity of striatal astrocytes, without modifying that of neurons or cortical astrocytes. Neither thapsigargin nor FK506 modified mitochondrial Ca(2+) buffering differences between cell types, excluding a predominant contribution of endoplasmic reticulum or calcineurin. These results provide additional insight into the mechanisms of striatal vulnerability, showing that the increased Ca(2+) vulnerability of striatal versus cortical mitochondria resides in both intact neurons and astrocytes, thus positioning the striatum at greater risk for disturbed neuron-astrocyte interactions. Also, the selective effect of CsA over striatal astrocytes suggests that in vivo neuronal sheltering with this compound may indirectly result from astrocytic protection.

FRET-based fluorescence probes for hydrolysis study and pig liver esterase activity

New fluorescent probes based on simple organic synthesis were designed and synthesized, and their hydrolysis catalyzed via base and pig liver esterase (PLE) was studied using FRET (fluorescence resonant energy transfer), with 1-naphthylacetic group as a donor and dansyl group as an acceptor. By simultaneous recording of changes of the donor fluorescence intensities, kinetic parameters for base-catalyzed and PLE-catalyzed hydrolysis can be determined. The presented FRET assay is a convenient and simple method and both fluorescent probes are good real-time indicators for the analysis of ester hydrolysis such as PLE activities.

Impaired Cerebral Autoregulation in a Case of Severe Acute Encephalitis

The status of cerebral autoregulation (CA) is an important prognostic factor for acute head trauma, but the role of CA in patients with acute encephalitis has not been previously discussed. We present the case of a 30-year-old woman with severe acute encephalitis who underwent craniectomy for intractable increased intracranial pressure (ICP). Preoperatively, adjustments of blood pressure (BP) with simultaneous recording of changes in cerebral blood flow velocity with transcranial Doppler indicated increased ICP and impaired CA. Postoperatively, ICP declined remarkably but CA remained impaired when the relationship between spontaneous fluctuation of mean BP and ICP was analyzed. Increased ICP recurred again within 24 hours of the decompression surgery and caused death of the patient. We propose that evaluating the status of CA could be of prognostic importance in patients with severe encephalitis.

Photoperiod, diapause and cold-hardiness

Great progress has recently been made in cryobiology. One field, however, has been neglected: the temporal sequence of the effects of photoperiod and temperature, and their relative importance in cold hardening. This is relevant to the question of impor- tance of diapause in cold-hardiness. Denlinger (1991) outlined the categories of such relations and stressed a great need for further detailed research. A survey of studies done over the past decade revealed many gaps in the evidence and the ambiguous nature of the data on the photoperiodic regulation of cold-hardiness. We hope that this review will stimulate further research in this field. Among several directions where research is most needed we have stressed (1) simultaneous recording of changes in survival and dynamics of suspected cryoprotectants (stressed also by Danks, 1996), (2) checking the regulation of different phases of cold hardening, and (3) discrimination between direct and indirect (mediated via neuroendocrine system) effects of environmental cues on cold harden- ing.

Temperature effects on hemocyanin oxygen binding in an antarctic cephalopod.

The functional relevance of oxygen transport by hemocyanin of the Antarctic octopod Megaleledone senoi and of the eurythermal cuttlefish Sepia officinalis was analyzed by continuous and simultaneous recordings of changes in pH and hemocyanin oxygen saturation in whole blood at various temperatures. These data were compared to literature data on other temperate and cold-water cephalopods (octopods and giant squid). In S. officinalis, the oxygen affinity of hemocyanin changed at deltaP50/degrees C = 0.12 kPa (pH 7.4) with increasing temperatures; this is similar to observations in temperate octopods. In M. senoi, thermal sensitivity was much smaller (<0.01 kPa, pH 7.2). Furthermore, M. senoi hemocyanin displayed one of the highest levels of oxygen affinity (P50 < 1 kPa, pH 7.6, 0 degrees C) found so far in cephalopods and a rather low cooperativity (n50 = 1.4 at 0 degrees C). The pH sensitivity of oxygen binding (delta log P50/delta pH) increased with increasing temperature in both the cuttlefish and the Antarctic octopod. At low PO2 (1.0 kPa) and pH (7.2), the presence of a large venous oxygen reserve (43% saturation) insensitive to pH reflects reduced pH sensitivity and high oxygen affinity in M. senoi hemocyanin at 0 degrees C. In S. officinalis, this reserve was 19% at pH 7.4, 20 degrees C, and 1.7 kPa O2, a level still higher than in squid. These findings suggest that the lower metabolic rate of octopods and cuttlefish compared to squid is reflected in less pH-dependent oxygen transport. Results of the hemocyanin analysis for the Antarctic octopod were similar to those reported for Vampyroteuthis--an extremely high oxygen affinity supporting a very low metabolic rate. In contrast to findings in cold-adapted giant squid, the minimized thermal sensitivity of oxygen transport in Antarctic octopods will reduce metabolic scope and thereby contribute to their stenothermality.

Characterisation of leather samples by non-invasive dielectric and thermomechanical techniques

A description is given how the dielectric coaxial technique measuring in the microwave region has been used for monitoring drying processes in leather samples. It is also shown how the coupling of this technique together with dynamic mechanical analysis enables the simultaneous recording of changes inthe dielectric properties, related to the moisture content of the material, together with the mechanical properties as a function of time or temperature. The samples studied include unaged and artificially aged goat and calf leathers. Measurements using the dynamic mechanical analyser are presented over a range of temperature which includes the shrinkage temperature. During the drying process, values of mechanical modulus or displacement and dielectric permittivity are recorded as a function of time or temperature which includes the temperature range of leather shrinkage, and from previous research report of Larsen [1] this has been associated with the chemical state of the leather samples.

Simultaneous optical imaging of intracellular Cl − in neurons in different layers of rat neocortical slices: advantages and limitations

Simultaneous recording of changes in intracellular Cl − concentration ([Cl −] i) in individual neurons situated in different layers (e.g. II/III–VI) of neocortical slices was found to be feasible by means of optical fluorescence measurements using 6-methoxy- N -ethylquinolinium iodide (MEQ). γ-Aminobutyric acid (GABA) caused a measurable increase in [Cl −] i in adult neocortical neurons, but a decrease in immature neurons. Developmental changes in the function of the Cl − pump and cation–Cl − co-transporters were evaluated using inhibitors such as furosemide (FURO), ethacrynic acid (ETA), and bumetanide (BMT). However, it was found that these inhibitors absorb and/or emit light of the wavelength that is used for the optical imaging of MEQ. In addition, quenching of MEQ fluorescence by Cl − and leakage of loaded MEQ was significantly enhanced at a higher temperature, which will limit experimentation at>30°C. Estimation of [Cl −] i in individual neurons in slices was made possible by calibrating intracellular MEQ fluorescence signals at known Cl − concentrations ([Cl −]) in the presence of tributyltin, a Cl −–OH − antiporter, nigericin, a K +–H +antiporter, and KSCN. This enables comparison of [Cl −] i between neurons in different slices. Thus, optical imaging of [Cl −] i in brain slices can provide valuable spatial information about [Cl −] i dynamics and homeostasis, although it should be emphasized that the technique does have some limitations.

Simultaneous recording of cytosolic Ca2+ levels inDidinium andParamecium during aDidinium attack onParamecium

The carnivorous ciliateDidinium nasutum captures prey such asParamecium by discharging extrusomes, known as toxicysts, while the attackedParamecium defensively discharges trichocysts. Several authors have suggested that both discharges, the toxicysts ofDidinium and the trichocysts ofParamecium, are evoked by the rise in cytosolic Ca2+ level in each cell. However, these putative increases in cytosolic Ca2+ levels have not as yet been recorded simultaneously in these cells during aDidinium attack onParamecium. We injected the fluorescent Ca2+ indicator Ca-Green 1 dextran into bothDidinium andParamecium, and simultaneously observed the cytosolic Ca2+ levels in these cells asDidinium attackedParamecium. When aParamecium came into contact with theDidinium proboscis, theDidinium showed a significant rise in cytosolic Ca2+ in the basal portion of the proboscis. One video frame (33 ms) after the onset of the Ca2+ rise inDidinium, theParamecium also showed an increase in cytosolic Ca2+. This is the first simultaneous recording of changes in the Ca2+ level during a predator-prey interaction in ciliates. The possible roles of these Ca2+ increases are discussed in relation to the discharge of toxicysts during theDidinium attack and of trichocysts as a defensive behavior ofParamecium.

Mechanisms underlying the rapid depolarization produced by deprivation of oxygen and glucose in rat hippocampal CA1 neurons in vitro.

Intracellular recordings were made to investigate the mechanism, site, and ionic basis of generation of the rapid depolarization induced by superfusion with ischemia-simulating medium in hippocampal CA1 pyramidal neurons of rat tissue slices. Superfusion with ischemia-simulating medium produced a rapid depolarization after approximately 6 min of exposure. When oxygen and glucose were reintroduced, the membrane potential did not repolarize but depolarized further, reaching 0 mV approximately 5 min after reintroduction. Simultaneous recordings of changes in cytoplasmic Ca2+ concentration ([Ca2+]i) and membrane potential recorded from 1-[6-amino-2-(5-carboxy-2-oxazolyl)-5-benzofuranyloxy]-2-(2- amino-5-methylphenoxy)-ethane-N,N,N',N'-tetraacetic acid pentaacetoxymethyl ester (Fura-2/AM) loaded slices revealed a rapid increase in [Ca2+]i in all CA1 layers corresponding to the rapid depolarization of the soma membrane. The result suggests that the rapid depolarization is generated not only in the soma but also in the apical and basal dendrites. Application of 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), DL-2-amino-4-phosphonobutyric acid, and DL-2-amino-3-phosphonopropionic acid or bicuculline did not affect the amplitude and the maximal slope. Reduction in the concentration of extracellular Ca2+ or addition of CNQX or DL-2-amino-5-phosphonopentanoic acid delayed the onset of the rapid depolarization. The amplitude of the rapid depolarization recorded with Cs acetate electrodes in tetraethylammonium-containing medium had a linear relationship to the membrane potential between -50 and 20 mV. The reversal potential was shifted in the hyperpolarizing direction by a decrease in either [Na+]o or [Ca2+]o, whereas the reversal potential was shifted in the depolarizing direction by a decrease in [Cl-]o or using CsCl electrodes. An increase or decrease in [K+]o did not affect the reversal potential. These results indicate that the rapid depolarization is Na+, Ca2+, and Cl- dependent. The lack of effects of changes in [K+]o is probably due to the accumulation of interstitial K+ before generating the rapid depolarization. Prolonged application of ouabain (30 microM) caused an initial small hyperpolarization, a subsequent slow depolarization, and a rapid depolarization. In summary, the present study has demonstrated that the rapid depolarization is voltage-independent and is probably due to a nonselective increase in permeability to all participating ions, which may occur only in pathological conditions. The underlying conductance change is primarily the result of inhibition of Na,K-ATPase activity in the recorded neuron.

Simultaneous non-invasive microwave dielectric spectroscopy and dynamic mechanical analysis for studying drying processes

The aim of this paper is to describe how a dynamic mechanical analyser can be used together with the microwave coaxial line technique. This coupling enables the simultaneous recording of changes in the mechanical properties and moisture content of materials as a function of time or temperature at a selected frequency. The sample is placed either directly under the probe or clamped in the sample holder of the dynamic mechanical analyser. Sample positioning and heating is accurately controlled by the mechanical analyser and its temperature controller. Samples can be subjected to a constant static force, a frequency or both. A micro probe, recently designed for measurements on semi-rigid and rigid surfaces [1], and connected to a network analyser was used to monitor the moisture content of the samples.

The impact of newborn on adult mice: Open-field behavior along with pullus index

The open-field- (OF) dependent parameters ambulation, thigmotactical wall-seeking, radial latency, retrieving and pullus index were tested in both nulliparous and primiparous females as well as in unmated and mated males of the Swiss albino strain. The mice were housed under separate conditions and recorded in the absence as well as the presence of a biological or unrelated 1-day old pup placed either in the center or by the wall in a familiar OF. The results revealed an ambulatory response of recognition of the newborn’s genetic origin in single-caged females and family-housed males. The young’s initial OF location was decisive for adult OF behavior. In general, housing conditions affected family-caged primiparous females most. The pullus index or attraction toward pups reflected a need to retrieve the young. Simultaneous recordings of changes in two or more OF-dependent parameters made an integrate whole of the results.

The effects of ventricular end-diastolic and systolic pressures on action potential and duration in anaesthetized dogs.

1. Although it is known that mechanical events in the heart influence the duration of the cardiac action potential, there is no quantitative information on the effects of independent changes in ventricular end-diastolic and systolic pressures. 2. Experiments were carried out on open-chest anaesthetized dogs in which the autonomic nervous influences on the heart were prevented and monophasic action potentials were recorded form the epicardial surface of the left ventricle. The duration of these action potentials was taken as the interval from the upstroke to the point of 90% repolarization. 3. Elevation of left ventricular peak systolic pressure, at constant end-diastolic pressure, significantly shortened the monophasic action potential. 4. Elevation of end-diastolic pressure at constant peak systolic pressure significantly lengthened the monophasic action potential. 5. Responses were not dependent on release of noradrenaline from sympathetic nerve terminals because they persisted after administration of bretylium tosylate. They were also not due to myocardial ischaemia because they persisted when coronary perfusion pressure was maintained at a constant high level. 6. Simultaneous recordings of changes in myocardial segment length showed the expected responses to changes in ventricular pressures: increases in shortening in response to increases in diastolic pressure and no consistent effect from changes in systolic pressure. 7. These investigations demonstrate the independent effects of changes in systolic and end-diastolic pressures on cardiac action potential duration. This effect is likely to be an effect of the mechanical events, i.e. contraction-excitation feedback. This response may be mediated through changes in myocardial fibre tension, the consequent changes in fibre shortening, or both.

Changes in steady potential level and in brain bioelectrochemical potential during orienting and conditioned reflexes in rabbits.

1. The orienting reaction in rabbits is accompanied by generalized shifts of SPL in the cortex in the absence of changes in BECP. 2. Changes in BECP appear only during conditioned reflex formation and develop during combination of the conditioned and reinforcing stimuli. During combination shifts of SLP also are observed, and in their configuration and amplitude they differ from those occurring during OR. 3. Simultaneous recording of changes in BECP and shifts of SLP developing during combination of conditioned and reinforcing stimuli shows that the two phenomena are the external manifestation of independent processes. 4. It is postulated that brain activity concerned with the perception and analysis of the informational significance of a stimulus is linked more closely with bioelectrical than with metabolic processes. During a combination of two stimuli in the process of conditioned reflex formation, besides the strengthening of activity linked with bioelectrical processes, a new type of activity accompanied by considerable metabolic shifts appears. 5. Recording changes in the electrochemical potential of an electrode made of inert metal is a highly rewarding method for studying the spatiotemporal organization of metabolic activity of the brain, connected with higher nervous activity.

New instrument for continuous and simultaneous recording of changes in ultrasonic attenuation and velocity

The study of microplasticity of pure single crystals at low temperatures (i.e., the study of the first movements of dislocations) implies the measurement of elastic and anelastic characteristics during tensile tests. Hence a new method has been developed for continuous and simultaneous recording of changes in ultrasonic attenuation and velocity. The attenuation measurement is obtained by the usual pulse-echo technique. The relative velocity measurement is obtained by automatic comparison between a reference square pulse and the attack front of a selected echo. The relative accuracy is 6x10(-6) with a sensitivity of 30 mV ns(-1) for frequencies up to 40 MHz. Application to dislocation studies in aluminium is reported.

Simultaneous recording of changes in relative impedance and air pressure during acoustic and non-acoustic elicitation of the middle-ear reflexes.

Intra—aural reflex responses for normal and pathological human ears were obtained while utilizing equipment constructed at Sahlgren's Hospital. Acoustic and tactile stimuli were employed to elicit reflexes. Responses were displayed simultaneously on two channels of a graphic recorder, indicating changes in amplitude and amplitude—phase of an 800 Hz probe tone in the recorded ear. Changes in air pressure in the same sealed auditory canal in response to middle—ear muscle contraction were simultaneously recorded on a third channel. The response pattern on the impedance indicator and on the pressure transducer system during acoustic stimulation are primarily due to the stapedial muscle reflex. In a small fraction of the group of normal subjects (13 %) it appears that contraction of both middle—ear muscles was elicited by acoustic stimulation. In the group in which the tensor muscle was the only functioning muscle in the middle ear, the tensor reflex could not be elicited by acoustic stimulation.

Transvascular fluid balance in the lung.

1. The transvascular fluid balance has been studied in isolated blood-perfused lungs of rabbit and cat. During periods of left atrial pressure (LAp) elevation, changes in preparation weight were measured. In some experiments simultaneous recordings of changes in blood volume, as judged by changes in emitted radioactivity from (51)Cr labelled red blood cells, were performed.2. In nine out of eleven experiments, elevation of LAp by 5 mm Hg within a test period of 8 min resulted in new weight stability and thus apparently in the establishment of a new transvascular fluid equilibrium. In five of these eleven experiments weight stability was also obtained on elevation of LAp by 10 mm Hg. When LAp was elevated further, transvascular fluid equilibrium was not obtained, and a continuous and eventually progressive outward flux of fluid occurred.3. In a preparation with the vasculature paralysed by papaverine in order to avoid vasomotor reactions, changes in plasma protein content caused immediate alterations in the weight slopes of the preparations. These alterations were interpreted as being due to changes in transvascular fluid transfer. Again new stable weights were obtained on moderate changes in plasma protein content.4. New weight and transvascular fluid equilibria seemed to be reached as a result of very small transvascular fluxes of fluid. The transvascular fluid balance in the lung may thus be dynamically maintained as a result of such small fluxes of fluid. The Starling hypothesis could account for this balance, provided that a small shift of fluid can cause sufficiently marked alterations in the osmotic and/or hydrostatic pressure gradient across the wall of the exchange vessels.5. The possible role of a small extravascular compartment with a high fluid colloid osmotic pressure is discussed in relation to transvascular fluid balance in the lung.

Simultaneous recording of changes in the membrane potential and tone of smooth muscle in vitro

A modification has been described of the sucrose gap method for recording resting and action potentials simultaneously with the registration of tension in the smooth muscle.