Common carp tissue reactions to surgically implanted radio tags with external antennas

Examination of common carp Cyprinus carpio , carrying implanted telemetry transmitters, showed that wound healing was incomplete after 4 months and completed after 1 year. Granulation tissue, which encapsulated the transmitter, adhered to the intestine and liver. The liver was infiltrated by the granulation tissue after 1 year. Epidermal tissue grew down the channel for the antenna, establishing a potential pathway for pathogens. No signs of infections, however, were found.     

AN INTRAPERITONEAL RADIO TRANSMITTER FOR SEA OTTERS

A small intraperitoneal radio transmitter was developed and used successfully in California sea otters. The transmitter weighs about 120 g and has an internal antenna. Thirty-five implanted transmitters were located for an average of 526 d. The carcasses of five animals that died were recovered; there were no complications associated with the transmitters in these individuals. Reproductive performance of the adult females with implanted transmitters appeared normal. The main advantages of this transmitter are its reliability and long life. It has enabled the collection of significant new information on California sea otters.     

Determination of safety distance limits for a human near a cellular base station antenna,adopting the IEEE standard or ICNIRP guidelines

This paper investigates the minimum distance for a human body in the near field of a cellular telephone base station antenna for which there is compliance with the IEEE or ICNIRP threshold values for radio frequency electromagnetic energy absorption in the human body. First, local maximum specific absorption rates (SARs), measured and averaged over volumes equivalent to 1 and to 10 g tissue within the trunk region of a physical, liquid filled shell phantom facing and irradiated by a typical GSM 900 base station antenna, were compared to corresponding calculated SAR values. The calculation used a homogeneous Visible Human body model in front of a simulated base station antenna of the same type. Both real and simulated base station antennas operated at 935 MHz. Antenna-body distances were between 1 and 65 cm. The agreement between measurements and calculations was excellent. This gave confidence in the subsequent calculated SAR values for the heterogeneous Visible Human model, for which each tissue was assigned the currently accepted values for permittivity and conductivity at 935 MHz. Calculated SAR values within the trunk of the body were found to be about double those for the homogeneous case. When the IEEE standard and the ICNIRP guidelines are both to be complied with, the local SAR averaged over 1 g tissue was found to be the determining parameter. Emitted power values from the antenna that produced the maximum SAR value over 1 g specified in the IEEE standard at the base station are less than those needed to reach the ICNIRP threshold specified for the local SAR averaged over 10 g. For the GSM base station antenna investigated here operating at 935 MHz with 40 W emitted power, the model indicates that the human body should not be closer to the antenna than 18 cm for controlled environment exposure, or about 95 cm for uncontrolled environment exposure. These safe distance limits are for SARs averaged over 1 g tissue. The corresponding safety distance limits under the ICNIRP guidelines for SAR taken over 10 g tissue are 5 cm for occupational exposure and about 75 cm for general-public exposure.     

Continuous remote monitoring of fish activity with restricted home ranges using radiotelemetry

Signal strength received by a fixed antenna increased as a transmitter was positioned closer to it and decreased as the transmitter was positioned further away. Depth and transmitter orientation also influenced signal strength, but these were less pronounced than the effect of distance. The variations in signal strength recorded from fixed distances, depths or orientations were low, suggesting that variation in signal strength only occurs if the transmitter is moved. The use of signal strength variation as a measure of fish activity over a 24 h period was compared with observed patterns of point habitat use of a live fish. Close correspondence of assessments of activity using signal strength variation and habitat use was observed. This study demonstrated the potential utility of radiotelemetry in association with point-in-time habitat use data to determine home-range and diel and seasonal patterns of fish activity over 24 h periods.     

Are long term negative effects from external tags underestimated? Fouling of an externally attached telemetry transmitter

An externally attached radio transmitter and antenna on a farmed Atlantic salmon Salmo salar was overgrown with green algae, mussels, seaweed and Balanus sp. after the fish had stayed at sea from December 1997-July 1998. This observation indicates that fouling may be an important factor, which is seldom considered when estimating negative effects from tags on the animals. Fouling increases the drag from the transmitter, and may affect the swimming speed, energy budget and behaviour of the fish. The effect is likely to be most pronounced in coastal waters.     

Increased acetylcholine synthesis and release following presynaptic activity in a sympathetic ganglion

Abstract: The acetylcholine (ACh) content of sympathetic ganglia increases above its normal level following a period of preganglionic nerve stimulation. In the present experiments, this extra ACh that accumulates following activity was labeled radioactively from [³H]choline and its specific activity was compared with that of ACh subsequently released during preganglionic nerve stimulation. The specific activity of the released ACh was similar to that of the total tissue ACh, suggesting that the extra ACh mixes fully with endogenous stores. The present experiments also show that transmitter release during neuronal stimulation is necessary for the poststimulation increase in transmitter store. However, the increase was not evident when transmitter release was induced by K⁺. It is concluded that both transmitter release and impulse invasion of the nerve terminals are necessary for the adaptive phenomenon to manifest itself. The role of choline delivery and choline acetyltransferase activity in generating the poststimulation increase in transmitter store was tested. When choline transport activity measured as choline analogue (homocholine) accumulation increased, ACh synthesis was increased and when transport activity was not increased, neither was ACh synthesis. There was no poststimulation increase in measured choline acetyltransferase activity.     

Glutamate, a neurotransmitter--and so much more. A synopsis of Wierzba III

It appears almost incredible that the first indications that glutamate excites brain tissue were obtained during the second half of the 20th century, that vesicles containing glutamate were demonstrated in glutamatergic neurons less than 25 years ago, and that glutamate was not accepted as the major excitatory transmitter until about the same time. During this span of time it has also become realized that glutamate is so much more than a conventional neurotransmitter: (1) astrocytes express vesicles accumulating glutamate by vesicular transporters akin to the vesicular glutamate transporters in glutamatergic neurons, and they release glutamate by exocytosis; (2) a series of metabolic processes in astrocytes (glutamate uptake, glutamine synthetase activity, glutamine release) are involved in neuronal reutilization of transmitter glutamate; (3) glutamine may also be utilized for synthesis of GABA, the major inhibitory transmitter; (4) de novo synthesis of glutamate accounts for 20% of cerebral glucose metabolism, all of which initially occurs in astrocytes, and at steady state a corresponding amount of glutamate is oxidatively degraded, mainly or exclusively in astrocytes; (5) tissue contents of glutamate/glutamine increase during enhanced glutamatergic activity, i.e., astrocytic de novo synthesis exceeds astrocytic metabolic degradation of glutamate.     

Glutamate uptake by a stimulated insect nerve muscle preparation

Recent reports suggest that glutamate may be the excitatory neuromuscular transmitter in insects. In this study, glutamate uptake by isolated cockroach nerve muscle preparations was investigated by means of chemical and electron microscope radioautographic techniques. We found that the preparation had a high affinity for glutamate and that nerve stimulation enhanced glutamate uptake. Chemical studies showed that the average tissue concentration of glutamate bound during a 1 hr incubation period in 10^-5 M glutamate-³H after nerve stimulation was 2.8 x 10^-5 M. Less than 1% of the radioactivity was present in the perchloric acid-precipitated protein fraction. Using electron microscope radioautography, we observed that sheath cells showed the highest glutamate concentration of all cellular compartments. Uptake was greater at neuromuscular junctions than in other regions of the tissue. The data suggest a possible mechanism for transmitter inactivation and protection of synapses from high blood glutamate.     

Changes in monoamine transmitter concentration in freshwater mussel tissues.

Freshwater mussels were analyzed for biogenic amine transmitter substances in gill tissue, suprabranchial nerve and blood. Gill tissue from normal pondwater-acclimated mussels contained significant amounts of monoamine neurotransmitter substances. In comparison with the suprabranchial nerve the gill tissue contained 42% of the dopamine, 7% of the serotonin and 490% of norepinephrine. Exposing the animals to deionized water (salt-depleted) resulted in a loss of transmitter substances from gill tissue, but serotonin reduction was modest. The mussel gill tissue content of serotonin and the precursor tryptophan was regulated at nearly constant levels. Serotonin is an important transmitter substance in mussels and the many functions it controls, including sodium transport regulation, would depend on its continued presence.     

Wearable slot antenna at 2.45 GHz for off‐body radiation: Analysis of efficiency,frequency shift,and body absorption

The interaction of body‐worn antennas with the human body causes a significant decrease in antenna efficiency and a shift in resonant frequency. A resonant slot in a small conductive box placed on the body has been shown to reduce these effects. The specific absorption rate is less than international health standards for most wearable antennas due to small transmitter power. This paper reports the linear relationship between power absorbed by biological tissues at different locations on the body and radiation efficiency based on numerical modeling (r = 0.99). While the ?10 dB bandwidth of the antenna remained constant and equal to 12.5%, the maximum frequency shift occurred when the antenna was close to the elbow (6.61%) and on the thigh (5.86%). The smallest change was found on the torso (4.21%). Participants with body‐mass index (BMI) between 17 and 29 kg/m² took part in experimental measurements, where the maximum frequency shift was 2.51%. Measurements showed better agreement with simulations on the upper arm. These experimental results demonstrate that the BMI for each individual had little effect on the performance of the antenna. Bioelectromagnetics. 39:25–34, 2018. © 2017 Wiley Periodicals, Inc.     

Tumour shape-dependent microwave hyperthermia using a novel coaxial micro-cut slot antenna

Given that the effectiveness of interstitial hyperthermia for cancer treatment is related to the temperature achieved during the ablation process, there is a need for an accurate understanding of the required temperature distribution which is affected by the physical shape and form of tumours. Although a maximum peak temperature value and minimum backward heating are desired, the temperature distribution needs to be not only high but also uniformly extended over a section instead of at one peak point, especially when a roughly oval-shaped tumour is aligned with the antenna. In this case, achieving a high temperature peak destroys only the central cancerous cells after the first minutes of ablation, leaving the cells on the side alive. In this paper, a complex model was extended for the study of the heat distribution of an antenna over a porous liver composed of blood, cancerous cells, and normal tissue. Three different types of antenna were analysed: single-slot, double-slot, and dipole-tip. A novel structure made up of the single-slot antenna with a micron cut, named the micro-cut slot (MCS) antenna, was proposed and analysed. Thanks to the new structure, high uniform temperature distribution with minimum backward heating was achieved. The extended model equations, which encompass a coupled nonlinear set of transient Maxwell's electromagnetic equations, extended Darcy–Brinkman equation, and local thermal non-equilibrium equations for porous medium approximation, were solved numerically using the novel alternating direction implicit, finite–difference time–domain approach. The results showed that each type of antenna could be useful if chosen according to the shape of the tumour. In comparison with previously used antennas, the MCS antenna presented a good combination of the required goals of achieving uniform high temperature distribution and minimum backward heating.     

Effect of Increasing Choline, In Vivo and In Vitro, on the Synthesis of Acetylcholine in a Sympathetic Ganglion

Abstract: The experiments described in this paper were designed to test whether increasing choline availability over normal physiological levels increases acetylcholine synthesis in the cat's superior cervical ganglion. When ganglia were perfused with Krebs solution, an increase in the medium's choline concentration over physiological (10⁻³M) levels increased tissue choline but did not increase tissue acetylcholine or the release of acetylcholine from stimulated ganglia. However, increasing plasma choline in the whole animal increased ganglionic acetylcholine levels. The basis for this difference in the effects of in vivo and in Vitro exposure to elevated choline levels on the tissue acetylcholine content was found to involve plasma factor(s), rather than indirect actions of choline, and the acetylcholine content of isolated ganglia was increased when the tissue was perfused with plasma, instead of Krebs solution, containing 10⁻³M-choline. The extra acetylcholine generated by this procedure was associated with a subsequent transient increase in transmitter release during short intervals of stimulation, but most of the extra acetylcholine was not readily available for release from stimulated ganglia. It is concluded that increasing choline available to sympathetic ganglia over physiological concentration does not have a sustained effect on the turnover of releasable transmitter under the conditions of these experiments.     

Quantal Mechanism of Transmitter Release during Progressive Depletion of the Presynaptic Stores at a Ganglionic Synapse : The action of hemicholinium-3 and thiamine deprivation

In the present experiments we interfered with the mechanism of acetylcholine (ACh) synthesis in the rat superior cervical ganglion by impairing the supply of either the choline group (hemicholinium no. 3 [HC-3]treatment) or the acetyl group (thiamine deprivation). Under both conditions stimulation causes in the ganglion a progressive decline in ACh output associated with a depletion of transmitter tissue content. ACh release from the terminals of a single preganglionic fiber was estimated from the quantum content value of the evoked excitatory postsynaptic potentials (EPSP's) recorded intracellularly in the ganglion neuron under test. The present observations indicate that Poisson statistics describe transmitter release at either low or high release levels. Furthermore, the progressive decline in the rate of ACh output occurring during repetitive stimulation is shown to correspond to a progressive decrease in the number of transmitter quanta released per impulse and not to any modification in the size of individual quanta. Some 8,000 transmitter quanta proved to represent the presynaptic transmitter store initially present in those terminals on a neuron that are activated by stimulation of a single preganglionic fiber. Speculations are considered about synaptic efficacy and nerve connections in rat autonomic ganglia. It is suggested that six preganglionic fibers represent the mean input to a ganglion neuron.     

A Kinetic Study of Stimulus-Induced Vesicle Recycling in Electromotor Nerve Terminals Using Labile and Stable Vesicle Markers

The kinetics of recovery, by recycling electromotor synaptic vesicles, of the biophysical parameters of the reserve population has been studied in perfused blocks of electric organ of Torpedo marmorata prestimulated in vivo, followed by density gradient separation of the extracted vesicles in a zonal rotor using labile (acetylcholine and ATP) and stable (proteoglycan) vesicle markers. Stimulation in vivo at 0.15 Hz for 3.3 h depleted tissue acetylcholine much less than stimulation at 1 Hz for 1 h but nevertheless generated a much larger pool of recycled vesicles that recovered more slowly. At the lower rate of stimulation, recovery of the biophysical characteristics of the reserve population by the recycled vesicles, identified by their content of newly synthesized transmitter, was essentially complete by 8 h. The stable proteoglycan marker was immunochemically assayed and was bimodally distributed in the vesicle-containing portion of the density gradient even in experiments with unstimulated or recovered tissue. The second peak corresponded with that of newly synthesized transmitter and was thus identified as containing the recycled vesicles. Its normalized acetylcholine/proteoglycan ratio was lower than that of the first peak, which is consistent with earlier findings that recycled vesicles, before recovery, are only partially loaded with transmitter. However, as expected, the proportion of total vesicular proteoglycan and acetylcholine associated with the recycled vesicle fraction was very much lower in preparations derived from unstimulated or recovered tissue than in those from recently stimulated tissue.     

Glutamic acid as a synpatic transmitter candidate in the dorsal sensory neuron: reconsiderations.

Two primary reasons which are emerging to suggest that glutamate is not a dorsal root transmitter are: 1) that free glutamate levels in the dorsal root vs. the ventral root are not sufficiently different to warrant a transmitter function in the dorsal root, and 2) the spinal cord glutamate levels do not significantly change (per g tissue) after dorsal root input section. Recent analyses suggest, however, that there is a highly significant depression of glutamate in the dorsal root when related to total free amino acid concentration changes after root injury. This is not seen in the peripheral nerve. Thus the dorsal vs. ventral root free glutamate concentration difference is highly significant metabolically. The failure to see a decrease in spinal cord gray glutamate levels after dorsal root section would appear to be explained by the fact that the spinal cord satellite cells and neurons have a higher free glutamate concentration than the entering dorsal roots along with a considerable perikaryal free amino acid pool for protein synthesis. This will mask any changes due to dorsal root section.Comparisons of excess free glutamate and substance P (the two leading dorsal root transmitter candidates) in the dorsal root compared to the ventral root have shown that there is a much larger excess of free glutamate in the dorsal root. This is true, even when considering the excitatory potency differences of these two substances. Thus, a very large free glutamate excess in the dorsal root is present with a relatively small concentration difference compared to the ventral root (where a transmitter role is not entertained). This fact could be of considerable metabolic significance in the regulation of transmitter levels of glutamate. The data available, therefore, are supportive of a possible glutamate transmitter role in a population of dorsal root fibers.     

Mobilization of the Readily Releasable Pool of Acetylcholine from a Sympathetic Ganglion by Tityustoxin in the Presence of Vesamicol

The present experiments tested whether preganglionic stimulation and direct depolarization of nerve terminals by tityustoxin could mobilize similar or different pools of acetylcholine (ACh) from the cat superior cervical ganglia in the presence of 2-(4-phenylpiperidino)cyclohexanol (vesamicol, AH5183), an inhibitor of ACh uptake into synaptic vesicles. In the absence of vesamicol, both nerve stimulation and tityustoxin increased ACh release. In the presence of vesamicol, the release of ACh induced by tityustoxin was inhibited, and just 16% of the initial tissue content could be released, a result similar to that obtained with electrical stimulation under the same condition. When the impulse-releasable pool of ACh had been depleted, tityustoxin still could release transmitter, amounting to some 10% of the ganglion's initial content. This pool of transmitter seemed to be preformed in the synaptic vesicles, rather than synthesized in response to stimuli, as tityustoxin could not release newly synthesized [3H]ACh formed in the presence of vesamicol, and hemicholinium-3 did not prevent the toxin-induced release. In contrast to the results with tityustoxin, preganglionic stimulation could not release transmitter when impulse-releasable or toxin-releasable compartments had been depleted. Our results confirm that vesamicol inhibits the mobilization of transmitter from a reserve to a more readily releasable pool, and they also suggest that, under these experimental conditions, there might be some futile transmitter mobilization, apparently to sites other than nerve terminal active zones.     

Antenna impedance matching with neural networks

Impedance matching between transmission lines and antennas is an important and fundamental concept in electromagnetic theory. One definition of antenna impedance is the resistance and reactance seen at the antenna terminals or the ratio of electric to magnetic fields at the input. The primary intent of this paper is real-time compensation for changes in the driving point impedance of an antenna due to frequency deviations. In general, the driving point impedance of an antenna or antenna array is computed by numerical methods such as the method of moments or similar techniques. Some configurations do lend themselves to analytical solutions, which will be the primary focus of this work. This paper employs a neural control system to match antenna feed lines to two common antennas during frequency sweeps. In practice, impedance matching is performed off-line with Smith charts or relatively complex formulas but they rarely perform optimally over a large bandwidth. There have been very few attempts to compensate for matching errors while the transmission system is in operation and most techniques have been targeted to a relatively small range of frequencies. The approach proposed here employs three small neural networks to perform real-time impedance matching over a broad range of frequencies during transmitter operation. Double stub tuners are being explored in this paper but the approach can certainly be applied to other methodologies. The ultimate purpose of this work is the development of an inexpensive microcontroller-based system.     

Use of radio telemetry for studying upriver migration of adult Atlantic salmon (Salmo salar)

This paper describes and evaluates a 50 mHz radio telemetry system for studying river movements of adult Atlantic salmon ( Salmo salar ). In fresh water for most applications radio telemetry is preferable to ultrasonic telemetry, because the receiving element (antenna) can be above water, and radio signals are scarcely affected by turbulent, weedy or ice-covered water. Within the range of 10–200 mHz higher frequencies are preferred, since the efficient antenna size is inversely proportional to frequency, and attenuation of signals is independent of frequency. Transmitters were cylindrical (6.5–9.6 cm long * 1.9 cm diam) with a 0.5 wavelength antenna trailing from one end. Each emitted pulsed signals on one of 20 crystal-controlled channels between 49.100 and 49.385 mHz. Transmitters were placed in the stomachs of salmon and the antenna trailed out the last gill slit. Receivers were portable 20-channel manual or automatic scan models, and antennas were 48 cm diam capacitor tuned loops. Some salmon regurgitated transmitters. Two salmon were recaptured and showed no ill effects from carrying transmitters for 32 and 42 days. Pulse rate had little effect on known transmitter life under natural conditions. Known tag life was variable, but averaged 70 days for transmitters with 1000 mah batteries. The range of transmission of transmitters to a receiving system in an airplane at 410 m altitude was about 10 km, and to a boat about 1 km. Range to a land vehicle was variable depending on obstructions. From the airplane transmitters can be located within a radius of about 50 m.     

Desensitization is a property of the cholinergic binding region of the nicotinic acetylcholine receptor, not of the receptor-integral ion channel.

The reversible acetylcholine esterase inhibitor (-)-physostigmine (eserine) is the prototype of a new class of nicotinic acetylcholine receptor (nAChR) activating ligands: it induces cation fluxes into nAChR-rich membrane vesicles from Torpedo marmorata electric tissue even under conditions of antagonist blocked acetylcholine binding sites (Okonjo, Kuhlmann, Maelicke, Neuron, in press). This suggests that eserine exerts its channel-activating property via binding sites at the nAChR separate from those of the natural transmitter. We now report that eserine can activate the channel even when the receptor has been preincubated (desensitized) with elevated concentrations of acetylcholine. Thus the conformational state of the receptor corresponding to desensitization is confined to the transmitter binding region, leaving the channel fully activatable-albeit only from other than the transmitter binding site(s).     

Calibration of position and angular data from a magnetic tracking device

This paper describes a method for calibrating data from a magnetic tracking device. Position and orientation data were collected in a 1. 6x0.8x1.4m(3) volume using a Polhemus Fastrak((R)) in conjunction with both a long-range and standard transmitter. Position and orientation data were calibrated using a locally linear model based on the position of the measurement. After calibration, the average position and angular errors were less than 1.8cm and 1.2 degrees up to 1.8m from the transmitter for the long-range transmitter. For the standard transmitter, even after calibration, errors increased sharply when the sensor was more than 1.2m from the transmitter. Up to that distance, post-calibration errors were less than 1.2cm and 1. 2 degrees, while up to 1.8m they were below 5cm and 4 degrees. These errors could be further reduced by noise filtering. However, use of the standard transmitter is not recommended at distance greater than 1.2m due to orientation-based effects. It was concluded that for the volume investigated, tracking devices could provide similar three-dimensional accuracy to video systems.