Bioimpedance measurements have previously shown that cancerous tissues in many cases have a higher characteristic frequency than normal tissues. This paper tries to find an index which is sensitive to variation in the characteristic frequency but is independent of the impedance value itself. Calculated indexes from several publications in most cases show values larger than one for cancerous tissues and less than one for normal tissues.

Animals↗

PubMedDate not supplied

Use of serum biochemistry to evaluate nutritional status and health of incubating common eiders (Somateria mollissima) in Finland.

During 1997-1999, we collected serum samples from 156 common eider (Somateria mollissima) females incubating eggs in the Finnish archipelago of the Baltic Sea. We used serum chemistry profiles to evaluate metabolic changes in eiders during incubation and to compare the health and nutritional status of birds nesting at a breeding area where the eider population has declined by over 50% during the past decade, with birds nesting at two areas with stable populations. Several changes in serum chemistries were observed during incubation, including (1) decreases in serum glucose, total protein, albumin, beta-globulin, and gamma-globulin concentrations and (2) increases in serum uric acid, creatine kinase, and beta-hydroxybutyrate concentrations. However, these changes were not consistent throughout the 3-yr period, suggesting differences among years in the rate of carbohydrate, lipid, and protein utilization during incubation. The mean serum concentrations of free fatty acids, glycerol, and albumin were lowest and the serum alpha- and gamma-globulin levels were highest in the area where the eider population has declined, suggesting a role for nutrition and diseases in the population dynamics of Baltic eiders.

3-Hydroxybutyric Acid↗

PubMedDate not supplied

Expression of Rhizobium galegae common nod clones in various backgrounds.

The cosmid clone pRg30, carrying common nodulation genes of Rhizobium galegae HAMBI 1174, and pRg33, a subclone of pRg30 that contains a 5.7-kb ClaI insert carrying nodDABC were conjugated into various Rhizobium nod- mutant strains and into a Ti plasmid-cured Agrobacterium tumefaciens. Complementation and expression of the nodABC genes of R. galegae were studied by following microscopically the infection process and the nodulation on different test plants. The nodABC genes of R. galegae complemented the nod- strains of other Rhizobium species. The presence of extra copies of common nod genes in the homologous R. galegae nodABC- strain induced an increased nodulation on Galega orientalis. However, the inserts of R. galegae in pRg30 and pRg33 do not carry sufficient genetic information for normal nodulation of test plants in an Agrobacterium background, because the Agrobacterium transconjugants induced root hair deformation on Galega plants, but no infection threads were detected and nodulelike structures developed only at low frequency. The Agrobacterium carrying the nodDABC of R. galegae did not cause the root hairs of Medigo sativa to deform.

Agrobacterium tumefaciens↗

PubMedDate not supplied

Quantitative assessment of impedance tomography for temperature measurements in hyperthermia.

The objective of this study is a non-invasive assessment of the thermal dose in hyperthermia. Electrical impedance tomography (EIT) has previously been given a first trial as a temperature monitoring method together with microwave-induced hyperthermia treatment, but it has not been thoroughly investigated. In the present work we have examined this method in order to investigate the correlation in vitro between the true spatial temperature distribution and the corresponding measured relative resistivity changes. Different hyperthermia techniques, such as interstitial water tubings, microwave-induced, laser-induced and ferromagnetic seeds have been used. The results show that it is possible to find a correlation between the measured temperature values and the tomographically measured relative resistivity changes in tissue-equivalent phantoms. But the uncertainty of the temperature coefficients, which has been observed, shows that the method has to be improved before it can be applied to clinical in vivo applications.

Body Temperature↗

PubMedDate not supplied

Pulse wave recording--development of a method for investigating foetal circulation in utero.

The need to investigate the elastic properties of arterial vessels 'in situ' for the early recognition of degenerative disorders in arteries has long been apparent. Volume pulses in defined segments of arteries can be evaluated for this purpose, and the present paper contains a survey of earlier attempts to quantify volume pulses by means of ultrasound. A presentation is given of a recently developed digital system, comprising a phase-locked echo tracker, capable of monitoring non-invasively the diameter and its pulsatile changes of a selected artery along two chosen image lines of a linear array ultrasound scanner. The physical limitations of tracking fast-moving ultrasound echoes by means of phase-locked range gating are reported and the advantage is emphasized of using a gate length of one full period. This system has been calibrated, tested and applied in measurements of pulse wave pattern and propagation velocity in the descending aorta of human foetuses in the last trimester of gestation. The present high-resolution echo-tracking method has yielded reproducible results in the foetus and appears suitable also for screening studies on adult vessels.

Blood Circulation↗

PubMedDate not supplied

Recording of foetal movements: a comparison of three methods.

As decreased foetal movement (FM) may indicate impaired foetal health, FM recording has been suggested as a method of assessing foetal well-being. A non-intrusive, automated method of recording FM (FM-detector), was compared with maternal and ultrasonographic assessment of FMs in 24 women in the third trimester of pregnancy. The FM-detector detected a greater proportion of ultrasonographically recorded FMs than the mothers did (median 70% and 38%, respectively; p less than 0.001). Parity, gestational age, placental site or thickness, maternal weight or the distance from the maternal abdominal surface to the amniotic cavity did not affect the ability of the FM-detector to detect ultrasonographically recorded FMs. The estimation of FM strength by the FM-detector agreed fairly well with the assessment of FM strength by the ultrasound observer. The FM-detector would seem suitable for clinical use, as in the examination of pregnant women complaining of feeling 'less FM'.

Adult↗

PubMedDate not supplied

An ultrasonic system for diameter pulse tracking in arteries: problems and pitfalls.

Non-invasive ultrasonic techniques for measuring the mechanical behaviour of large arteries have a potential clinical application for physiological studies of the circulation and early detection of degenerative arterial disorders. A newly developed system for such purposes, comprising two double-echo trackers with zero-crossing phase-locked circuits and interfacing a B-mode real-time scanner, has been introduced for on-line recording of the diameter in a selected aortic segment. The aim of this report is to draw attention to the limitations of the technique in order to avoid misinterpretation of results. The various problems associated with the use of phase-locked echo followers for tracking sonic echoes of vessel pulse waves are summarized. The high spatial resolution of the measuring system is essential for estimating the elastic properties of the vessel, because the fractional changes of the diameter waveform during a heart cycle are small compared with the swings of intravascular pressure. Measuring errors may originate from either human or technical sources. From several viewpoints correct alignment of the ultrasonic beam vis-à-vis the vessel segment under consideration is crucial for obtaining valid measures. A thorough knowledge of the physics involved is essential for an adequate use of the instrument. With correct use, easily reproducible and reliable estimations are obtained of the mechanical properties of large vessel walls.

Aorta, Abdominal↗

PubMedDate not supplied

Waveform generator for electrical impedance tomography (EIT) using linear interpolation with multiplying D/A converters.

This paper describes the implementation of a multiplying digital-to-analogue (D/A) converter as a programmable waveform generator to be used in an electrical impedance tomography (EIT) system. Different digital techniques of generation waveforms are considered and the advantages and disadvantages of the chosen slope-plus-pedestal technique are presented. A wire-wrapped prototype system has been designed, and from measured frequency spectra the total harmonic distortion can be calculated to values between 1.1 and 2.9% depending on frequency.

Analog-Digital Conversion↗

PubMedDate not supplied

[Trembling in slaughtering pigs--an analysis of Swedish swine stock monitoring].

The incidence of trembling symptoms among pigs in the Swedish pig progeny testing scheme was highest among Land-race pigs (11%), Tab. I). Yorkshire, Hampshire and Duroc pigs had an incidence below 1%. Data on the incidence of trembling symptoms among 1716 adolescent Land-race pigs from one Swedish pig progeny testing station were analysed. The results showed no statistically significant difference in occurrence between sexes. According to Table II there were some phenotypic relationships between trembling and production traits. Pigs with trembling symptoms showed a higher daily gain as piglets, had a longer carcass and more lean in the carcass than non-trembling pigs. The heritability for trembling symptoms was estimated to be around 0.4.

Animals↗

PubMedDate not supplied

Psychological prognosis of diagnosed chronic organic solvent intoxication.

The psychological prognosis of 86 patients (40 men and 46 women) with previously diagnosed chronic solvent intoxication due to trichloroethylene, perchloroethylene, or solvent mixtures was studied after a follow-up period (mean 5.9 years). The patients' mean age at the time of diagnosis was 38.6 years, and the mean duration of solvent exposure was 10.7 years. Tests for intelligence, short-term memory, and sensory and motor functions were applied. The group means of the patients' intellectual functions were increased after the follow-up period. At the group level, the scores on one sensorimotor task and tasks requiring manual dexterity were lower. Individual patients performed better, worse, or equally when the results of the initial examination and the reexamination were compared. The overall prognosis of psychological test results was better with a longer follow-up period and lower age. Patients who used drugs with neurological effects had a poorer overall psychological prognosis. The characteristic of solvent exposure were related only to the prognosis of some single tests for sensory and motor functions.

Adult↗