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At least 397 records · Page 22Linked to original sources
PubMed1996

[Surgery of congenital radio-ulnar synostosis. Technical error and therapeutic strategy].

PURPOSE OF THE STUDY: A clinical feature of surgery in congenital radioulnar synostosis is described. MATERIAL AND METHODS: A eighteen year old right handed woman, was hampered when she works by a left congenital radio ulnar synostosis. Clinical examination showed a left forearm locked in 75 degrees of pronation. Radiographs showed a proximal synostosis. Surgical treatment associated a resection of the synostosis with silastic interposition, resection of the distal end of the ulna, and derotational middle-third osteotomy of the radius. RESULTS: Three months later, the pronosupination was 90 degrees, but an ischemic retraction of the flexor pollicis longus muscle appeared with a non-union of the radius. A second procedure was necessary to put a plate in compression on bone and to release the muscle. Twenty years later, the forearm was locked in neutral pronosupination, without recurrence of synostosis on radiographs. DISCUSSION: Surgical treatment in congenital radio ulnar synostosis associates many problems: indication (often for discomfort), ideal age (more vascular or nervous post operative complications if older), technical (failure of operations with functional aim). CONCLUSION: A review of international litterature allows the authors to suggest a specific management for congenital radio ulnar synostosis.

Adolescent↗
PubMed1996

Can radio-opaque markers be used to measure mouth-to-stoma transit time in ileostomates?

OBJECTIVE: To determine whether radio-opaque markers can be used to assess mouth-to-stoma transit time (MSTT) in ileostomates. DESIGN: Criterion standard. SETTING: Metabolic research unit. SUBJECTS: Five volunteer ileostomates. RESULTS: MSTT assessed by radio-opaque markers (11.3 to 12.5 h) was significantly longer (P < 0.5) than that calculated by ileal recovery of dietary starch (6.5 to 8.8 h), the criterion standard. CONCLUSION: Radio-opaque markers are unsuitable for measurement of MSTT in ileostomates.

Contrast Media↗
PubMed1995

Fading characteristics of a 2.3 GHz radio telemetry channel in a hospital building.

This paper reports on radio path attenuation measurements made in a hospital complex at a spot frequency of 2.340 GHz. Power loss figures for fixed path propagation in a variety of building types have been determined for proposed telemetry use in operational ward situations. Throughout the hospital, the radio paths assessed all exhibited a loss in excess of that calculated for free-space communications. Modern buildings had external wall losses of 10-25 dB, with dividing walls in wards contributing an additional 5 dB. Received signal strength levels indicated a Rayleigh distribution for obstructed paths. Temporal testing was used to find the rate and depth of signal fades caused by the movement of personnel and equipment during normal ward usage; signal level reductions of greater than 35 dB were common during busy periods.

Biomedical Engineering↗
PubMed2000

[Cellular radio systems. Problems faced in assessing exposure to electromagnetic fields].

Over twenty years of its existence, cellular radio systems have become one of the major sources of human exposure to electromagnetic field (EMF) of high frequency. With the increasing number of cellular phones, the interest in health effects of exposure to EMF emitted by them continues to grow. At present, there is a general opinion that thermal effect (change of electromagnetic energy into thermal energy) is an essential mechanism of possible biological effects. The majority of world standards for exposure to EMF are based on this effect. The author presents Polish standards and those of the International Commission on Nonionizing Radiation Protection (ICNIRP) for EMF of frequencies used in cellular radio systems, both basic that limits SAR (Specific Absorption Rate), and derived that limits the power density, as well as intensity of electric and magnetic fields. Attention was also turned to the problems concerning the application of cellular phones and those resulting from the character of the field emitted by them to which their users are exposed. Bearing in mind the results of the laboratory analyses of SAR values occurring in the user's head, and measurements of power density in the vicinity of the base station antennas, it can be stated that, in view of binding and recommended standards, cellular phones do not present any hazard to their users (private or professional). However, it should be stressed that standards adopted protect the user's head against the thermal effect, whereas the question on whether they also protect against non-thermal effects still remains without answer.

Electromagnetic Fields↗
PubMedDate not supplied

Guidance article: cellular telephones and radio transmitters--interference with clinical equipment.

It has long been recognized that devices emitting radio frequencies can interfere with the operation of clinical and other electronic equipment. A number of Health Devices System members have called us in recent months to ask about the risks of using cellular telephones in hospitals, and several others have also raised similar questions in the Healthcare Technology conference area of ECRINet, our online communication service. While some of those making inquiries have been alarmed by the publicity surrounding the possible health hazards of using cellular telephones--a specter that is not supported by currently available evidence or theoretical considerations--the focus of concern is generally whether such telephones can affect the operation of patient care devices. Evidence indicates that operating cellular telephones and radio transmitters near certain clinical equipment presents the risk of interrupting patient care, although much work remains to be done to clearly define that risk. Nevertheless, we recognize the benefit of bringing to the attention of our readers some of the experiences that are being reported. We hope that the following questions and answers will increase awareness of the possible risks of using such equipment, as well as promote the exchange of information to permit a more rapid assessment of the degree of risk and the steps necessary to avert problems.

Electronics, Medical↗
PubMed2003

Epidemiological studies of radio frequency exposures and human cancer.

Epidemiological studies of radio frequency (RF) exposures and human cancers include studies of military and civilian occupational groups, people who live near television and radio transmitters, and users of mobile phones. Many types of cancer have been assessed, with particular attention given to leukemia and brain tumors. The epidemiological results fall short of the strength and consistency of evidence that is required to come to a conclusion that RF emissions are a cause of human cancer. Although the epidemiological evidence in total suggests no increased risk of cancer, the results cannot be unequivocally interpreted in terms of cause and effect. The results are inconsistent, and most studies are limited by lack of detail on actual exposures, short follow-up periods, and the limited ability to deal with other relevant factors. In some studies, there may be substantial biases in the data used. For these same reasons, the studies are unable to confidently exclude any possibility of an increased risk of cancer. Further research to clarify the situation is justified. Priorities include further studies of leukemia in both adults and children, and of cranial tumors in relationship to mobile phone use.

Brain Neoplasms↗
PubMed2001

No effects of pulsed radio frequency electromagnetic fields on melatonin, cortisol, and selected markers of the immune system in man.

There is growing public concern that radio frequency electromagnetic fields may have adverse biological effects. In the present study eight healthy male students were tested to see whether or not radio frequency electromagnetic fields as used in modern digital wireless telecommunication (GSM standard) have noticeable effects on salivary melatonin, cortisol, neopterin, and immunoglobulin A (sIgA) levels during and several hours after exposure. In a specifically designed, shielded experimental chamber, the circularly polarized electromagnetic field applied was transmitted by an antenna positioned 10 cm behind the head of upright sitting test persons. The carrier frequency of 900 MHz was pulsed with 217 Hz (average power flux density 1 W/m2). In double blind trials, each test person underwent a total of 20 randomly allotted 4 hour periods of exposure and sham exposure, equally distributed at day and night. The results obtained show that the salivary concentrations of melatonin, cortisol, neopterin and sIgA did not differ significantly between exposure and sham exposure.

Adult↗
PubMed2001

Induced current measurements in whole body exposure condition to radio frequency electric fields.

The current induced in a human exposed to radio frequency electric fields has been studied by the use of a stripline, in which whole body exposure to vertical electric fields (3-27 MHz) can be produced. We have examined two different techniques to measure the induced current; parallel plate meters and current probes. When the subject has good connection to the ground, the choice of measurement technique is not crucial, since there are only minor differences in readings between the instruments. But when the subject is wearing shoes and/or standing on a wooden plate, the difference between the instruments increases considerably. The difference can mainly be explained by the capacitive coupling between the parallel plate meters and the ground; therefore, the current probes are preferred when the subject does not have perfect contact with the ground. Since the International Commission on Non-Ionizing Radiation Protection guidelines demand measurements of induced current in humans exposed to radio frequency fields in the range of 10-110 MHz, the importance of finding an appropriate measurement procedure becomes apparent.

Biophysics↗
PubMed2000

Comprehension and storage of four serially presented radio news stories by mild aphasic subjects.

The present study investigated aphasic subjects' ability to comprehend and store serially presented discourse. Sixteen mild aphasic subjects, eight age-matched normals, and eight younger normals listened to four serially presented radio news stories and a single radio news story. Half of the aphasic subjects performed as well as age-matched normals in a single-news-story comprehension task. However, they demonstrated a drastic deterioration in performance when asked to listen to a series of four news stories. Age-matched normals, and aphasic subjects, to a lesser extent, showed an impairment in the comprehension and storage of the news story heard last in a series of four news stories. These results were discussed in terms of the comprehension and storage resources of working memory.

Aphasia↗
PubMed2000

Radio-telemetric evidence of migration in the gregarious but not the solitary morph of the Mormon cricket (Anabrus simplex: Orthoptera: Tettigoniidae).

The Mormon cricket, Anabrus simplex, is one of just a few species of katydids (or bushcrickets, Orthoptera: Tettigoniidae) that, like migratory locusts, appear to have solitary and migratory morphs. Using radio telemetry we studied movements of individuals of two morphs of this flightless species. Individuals within each migratory band had similar rates of movements along similar directional headings whereas solitary individuals moved little and showed little evidence of directionality in movement. Our results also add to other recent radio-telemetry studies showing that flightless insects of 1-2 g in mass can be tracked successfully using these methods.

Animals↗
PubMed1985

Using the Very Large Array (VLA) and other radio telescopes to perform a parasitic Search for Extraterrestrial Intelligence (SETI).

This paper describes several attempts to utilize various radio telescopes in a manner that we term "parasitic," that is in a manner that does not interrupt or seriously impact the standard astronomical observing programs in progress at the radio observatories. In the extreme case, only recorded astronomical data are accessed off-line, after the fact, without any burden on the observatory at all.

Astronomy↗
PubMed1989

Radio frequency interference at Jodrell Bank Observatory within the protected 21 cm band.

Radio frequency interference (RFI) will provide one of the most difficult challenges to systematic Searches for Extraterrestrial Intelligence (SETI) at microwave frequencies. The SETI-specific equipment is being optimized for the detection of signals generated by a technology rather than those generated by natural processes in the universe. If this equipment performs as expected, then it will inevitably detect many signals originating from terrestrial technology. If these terrestrial signals are too numerous and/or strong, the equipment will effectively be blinded to the (presumably) weaker extraterrestrial signals being sought. It is very difficult to assess how much of a problem RFI will actually represent to future observations, without employing the equipment and beginning the search. In 1983 a very high resolution spectrometer was placed at the Nuffield Radio Astronomy Laboratories at Jodrell Bank, England. This equipment permitted an investigation of the interference environment at Jodrell Bank, at that epoch, and at frequencies within the 21 cm band. This band was chosen because it has long been "protected" by international agreement; no transmitters should have been operating at those frequencies. The data collected at Jodrell Bank were expected to serve as a "best case" interference scenario and provide the minimum design requirements for SETI equipment that must function in the real and noisy environment. This paper describes the data collection and analysis along with some preliminary conclusions concerning the nature of the interference environment at Jodrell Bank.

Astronomy↗
PubMed1986

Hypothalamic obesity: comparison of radio-frequency and electrolytic lesions in male and female rats.

Obesity-inducing lesions of the ventromedial hypothalamus (VMH) have generally been produced by passing anodal electrolytic current through a stainless steel electrode, which in addition to tissue ablation leaves deposits of metallic ions that might chronically irritate surrounding tissue. Although a few early investigators reported that nonirritative lesions (i.e., those that do not leave deposits) resulted in little or no obesity, their results were largely ignored when others observed substantial weight gain in animals after using the same techniques. The results of the present experiment suggest that these discrepancies were the result of a sex difference (the former group of studies all used male rats, while the latter group all used females). Male rats in the present study gained less than 80% of the weight gained by female rats regardless of lesion type, while rats with nonirritative radio-frequency lesions gained about 60% of the weight gained by rats with electrolytic lesions regardless of sex. Thus, female rats with radio-frequency lesions displayed substantial (albeit suppressed) weight gain, whereas male rats with identical lesions gained only slightly more weight than sham-lesioned controls. It is concluded that obesity resulting from electrolytic lesions of the VMH is due in part to tissue ablation and in part to chronic irritation (possibly of parasympathetic efferents mediating insulin release).

Animals↗
PubMed2000

Miniature stereo radio transmitter for simultaneous recording of multiple single-neuron signals from behaving owls.

Wireless radiotelemetric transmission of neuronal activity is an elegant technique to study brain-behavior interaction in unrestrained animals. In the current study, a miniature FM-stereo radio transmitter is described that permitted simultaneous recordings from two microelectrodes in behaving barn owls. Input from two independent channels is multiplexed to form a stereo composite signal that modulates a radio frequency carrier. The high quality of broadcasted extracellular signals enabled separation of single units based on differences in spike waveforms. Recording several single cells from different electrodes allows the possibility of investigating correlations between small, distributed neuronal ensembles. Multi-channel radiotelemetry that meets the demands of modern electrophysiology might open a new perspective for combined behavioral/neurophysiological approaches in freely-behaving animals.

Action Potentials↗
PubMed2002

Cellular telephones and effects on the brain: the head as an antenna and brain tissue as a radio receiver.

Headache and other neuropsychological symptoms occur in users of cellular telephones, and controversy exists concerning risks for brain cancer. We hypothesize these effects result from the head serving as an antenna and brain tissue as a radio receiver. The frequencies for transmission and reception by cellular telephones, about 900 MHz for analog and 1800 MHz for digital transmission, have wavelengths of 33-35 and 16-17 cm, respectively. Human heads are oval in shape with a short axis about 16 to 17 cm in length. Near the ear there will be a cross-section in the head with an axis half the wavelength of RF/MW transmissions of 900 MHz and equal to the wavelength of RF/MW transmissions at 1800 MHz. Therefore, the human head can serve as a lossy resonator for the electromagnetic radiation emitted by the cellular telephone, absorbing much of the energy specifically from these wavelengths. Brain cells and tissues demodulate the cell-phone's audio frequencies from the radio frequency carrier. Low audio frequencies in the ranges of alpha and beta waves affect these waves and thereby influence brain function. These effects state the case for a precautionary policy.

Auditory Perception↗
PubMed1998

Alzheimer's disease as a defect of neuronal autotrophism: a hypothetical analogy with amateur radio operation.

Amyloid precursor protein appears to be a signaling protein that plays a role in neuronal autotrophism, indicating integrity of the nerve terminal and synapse. Analogous to amateur radio operation with a damaged antenna in which further attempts to improve signal propagation can result in damage to the radio equipment, abnormal signaling by the secreted amyloid precursor protein stimulates compensatory metabolic activity in the neuron that ultimately leads to paired helical filament formation (neurofibrillary tangles) and further neuronal dysfunction and death.

Alzheimer Disease↗
PubMedDate not supplied

A method of radio-frequency inhomogeneity correction for brain tissue segmentation in MRI.

An automatic method of correcting radio-frequency (RF) inhomogeneity in magnetic resonance images is presented. The method considers that image intensity variation due to radio-frequency inhomogeneity contains not only low frequency components, but also high frequency components. The variation is regarded as a multiplication of low frequency (capacity variation of coil) and the frequency of object (true image). The efficiency of the proposed method is illustrated with the aid of both phantom and physical images. The impact of the inhomogeneity correction on brain tissue segmentation is studied in detail. The results show significant improvement of the tissue segmentation after inhomogeneity correction.

Brain↗
PubMed1999

Pretesting Spanish-language educational radio messages to promote timely and complete infant immunization in California.

California's Hispanic infants have lower immunization levels than non-Latino white infants, 53.7% versus 65.2%, respectively. Spanish-language radio is an effective mass media venue for imparting information to Latino populations. It has been demonstrated that lack of parental knowledge of infant immunization timing is associated with delayed immunization coverage. In an effort to improve Latino parent knowledge of immunization timing, two Spanish-language radio commercials were developed to be used in conjunction with community-based educational efforts. In order to gage the potential educational impact of the two commercials, they were pretested with a group of low-income Spanish-speaking Latino parents who represented members of the target population for whom the commercials were created. Both commercials were rated favorably by parents, and elicited immunization-specific responses. Although correct recall of the simplified, basic immunization schedule was low, the level of immunization response consistency and overall approval of both commercials appear to support their use as part of Latino infant immunization educational outreach in California.

Adult↗