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Biomedical subjects

J Janata

Publications and source records attributed to J Janata.

18 recordsLinked to original sources
PubMed1992

Investigation of AC-DC magnetic field effects in planar phospholipid bilayers.

Observations recently reported by others indicate that a combination of a weak dc magnetic field and extremely-low-frequency ac magnetic field can produce resonant effects in biological systems. We report measurements of the effects of combined dc and ac magnetic fields on the dc current through channel-free planar phospholipid membranes. The combined dc-ac magnetic fields did affect the dc current through planar phospholipid membranes, but not in every membrane, and not consistently at the same values of magnetic flux density and frequency. None of our measurements showed resonant response akin to the cyclotron-like resonance reported in diatoms [Smith et al., 1987] and lymphocytes [Liboff et al., 1987].

Electromagnetic Fields↗
PubMed1992

Calcium binding to metallochromic dyes and calmodulin in the presence of combined, AC-DC magnetic fields.

The possibility that weak, ac and dc magnetic fields in combination may affect binding equilibria of calcium-ions (Ca2+) was investigated with two metallochromic dyes as calcium-binding molecules: murexide and arsenazo III. Calcium-dye equilibria were followed by measuring solution absorbances with a fiber-optic spectrophotometer. A Ca(2+)-arsenazo solution was also used indirectly to monitor the binding of Ca2+ to calmodulin. Parallel, ac and dc magnetic fields were applied to each preparation. The ac magnetic field was held constant during each of a series of experiments at a frequency in the range between 50 and 120 Hz (sine wave) or at 50 pps (square wave) and at an rms flux density in the range between 65 and 156 microT. The dc magnetic field was then varied from 0 to 299 microT at 1.3 microT increments. The magnetic fields did not measurably affect equilibria in the binding of metallochromic dyes or calmodulin to Ca2+.

Arsenazo III↗
PubMed1990

Ion transport in erythrocytes of Prague hypertensive rat.

The Prague hypertensive rat is a unique strain exhibiting genetic hypertension in which a hypertensive line (PHR) was bred in parallel with a normotensive one (Prague normotensive rat--PNR) from the same parental pair. Sodium efflux from Na(+)-loaded erythrocytes into Mg2(+)-sucrose medium was measured in these two strains as well as in spontaneously hypertensive rats (Okamoto-Aoki, SHR) and in normotensive outbred Wistar rats. Kinetic parameters--maximal velocity and apparent dissociation constant (reflecting the affinity for internal sodium)--were calculated. It was found that PHR as well as SHR had a higher Na+ leak and a decreased activity of the ouabain-sensitive Na+ transport as compared to Wistar rats. Furosemide-sensitive Na+ transport was substantially lower in erythrocytes of both hypertensive strains (PHR and SHR) than in the respective normotensive strains (PNR and Wistar).

Animals↗
PubMed1988

Chemical sensors.

Explore the source record for details and available documents.

Electrochemistry↗
PubMed1978

[Combined intra-uterine and ectopic pregnancy following the treatment with clomiphen (author's transl)].

Report on a case of combined pregnancy in a 25 year old patient who was treated with Clomiphen for anovulatory cycles. The left tubal pregnancy was removed at 12 weeks gestation. The intra-uterine pregnancy resulted in a term delivery of a 3 kg. 670 g. normal infant. Combined pregnancies rarely occur without treatment with ovulation inducing agents by superfecundation and superfetation. Ovulation inducing agents increase the theoretical possibility of combined pregnancy. Obstetricians should be alert to the possibility of combined pregnancy following induction of ovulation.

Adult↗
PubMed1976

Chemically sensitive field-effect transistors.

The present state of the art and trends in development of chemically sensitive field-effect transistors are reviewed. In the theoretical section, a brief description of principles, temperature sensitivity, stability and the question of a reference electrode are discussed. In the practical section some aspects of the design and recommendations for device evaluation procedures are given. The article concludes with the authors' view of future development, particularly with respect to biomedical applications.

Electrochemistry↗