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Biomedical subjects

Y Wada

Publications and source records attributed to Y Wada.

At least 1,063 records · Page 59Linked to original sources
PubMed1980

Low frequency dielectric relaxation and light scattering under AC electric field of DNA solutions.

Low frequency dielectric relaxation of aqueous DNA was measured in a frequency range from 0.1 Hz to 30 kHz. Agreement was found between dielectric relaxation time and rotational one estimated from reduced viscosity for dilute solutions of DNA. The low frequency relaxation is thus ascribed to rotation of the major axis of DNA chains elongated by electrostatic repulsion between charges on the chain. A quasi-permanent dipole moment of DNA estimated from the dielectric increment is well explained by the fluctuation of dissociation of DNA. The above conclusion was confirmed for DNA samples of various molecular weights and for solutions in water ethanol mixtures. Effects of binding of salts and dyes are also interpreted in terms of the same mechanism. Light scattering of aqueous DNA under a.c. electric field supports the above conclusion.

Animals↗
PubMed1980

New method for simultaneous measurement of frequency spectra of complex dielectric constants of polyelectrolyte solutions.

A high-speed and high-accuracy measurement of relaxational frequency spectra of complex dielectric constants of polyelectrolyte solutions with a high conductivity was realized by a new digital signal processing technique. In this method, a sum of sinusoidal waves of geometrical series of frequencies is utilized as a multifrequency excitation signal and demodulation of the resulting response is carried out simply by addition and subtraction of digital signals in a minicomputer. This new technique is superior to the conventional cross correlation method using the fast Fourier transform in that it greatly reduces the processing time and avoids effectively the influence of a quantization error. The result for a DNA solution obtained by this method is presented to demonstrate the utility of this method.

Journal Article↗
PubMed1980

Effect of phalloidin on platelet aggregation.

By the addition of phalloidin, an oligopeptide of Amanita phalloides, to platelet-rich plasma, an increase of its transparency could be observed. The rate of increase of transparency was slow but the maximal intensity corresponded to that of ADP aggregation. Morphologically, many microfilaments were formed in the cytoplasm. But the figures were different from those in platelets in ADP aggregation.

Adenosine Diphosphate↗
PubMed1980

[Prolactin secretion during normal pregnancy and puerperium, particularly with regard to nursing (author's transl)].

The present study reveals that the serum prolactin (PRL) levels in early stage of pregnancy exceeded those of the non-pregnant women and rose gradually throughout pregnancy. Within a few days after delivery, PRL declined from maximum values at the end of pregnancy. In non-lactating women serum PRL returned to non-pregnant levels within about one month after delivery, but still remained above non-pregnant levels in lactating women. About one month after delivery serum estradiol was higher in non-lactating than lactating. LH and FSH showed no significant differences between non-lactating and lactating, and were similar to the levels of follicular phase. Therefore the role of PRL on puerperal infertility is thought to have no suppressive effect on the tonic secretion of pituitary gonadotropins and PRL may have a direct effect on the ovary. The excessive response of serum PRL to TRH administration (500 micrograms, i.v.) was observed in lactating women on the 5th postpartum day and during the 28-35 day period, but not during the 90-120 day period. Women given TRH 60 min after the onset of suckling on the 5th postpartum day displayed a relative small increase in serum PRL compared with those after 240 min. The response of PRL to TRH was probably affected by suckling.

Breast Feeding↗
PubMed1980

[Anti-inflammatory effects of prednisolone 17-valerate 21-acetate, a new topical corticosteroid (author's transl)].

Anti-inflammatory activities of prednisolone 17-valerate 21-acetate(PVA) were studied in rats and guinea pigs and results compared with data on topical steroids, such as betamethasone 17-valerate(BV) and hydrocortisone 17-butyrate(HB). PVA given subcutaneously inhibited dose-dependently carrageenin- and kaolin-induced edema. These anti-inflammatory activities of PVA were the weakest among the steroids tested. A local administration of PVA into the site of inflammation, however, had the same or more potent activities than BV and HB in carrageenin-induced edema and paper disk granuloma. Topical application of PVA ointment in carrageenin-induced edema exhibited an inhibitory effect which was dependent on the concentrations (0.1-1.0%). The anti-inflammatory activity of 0.3% PVA ointment was equivalent to that of 0.12% BV ointment. For the other experimental models, i.e. exuberant granulation, croton oil-induced ear edema, passive cutaneous anaphylaxis and tuberculin-induced delayed type hypersensitivity, the activity of 0.3% PVA ointment was the same or somewhat more potent than 0.12% BV and 0.1% HB ointments. The thymolytic activity of PVA ointment in the exuberant granulation model was similar to the activity seen with HB ointment and weaker than of BV ointment. Thus, the anti-inflammatory activities of PVA were equivalent to or more potent than those of BV and HB, and with topical application, the systemic effect of PVA was weaker than the other steroids examined.

Administration, Topical↗