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Biomedical subjects

F Suzuki

Publications and source records attributed to F Suzuki.

At least 577 records · Page 32Linked to original sources
PubMed1980

Properties of the fibers in the pathways along the anterior and posterior portions of the left A-V ring.

A comparison was made of the electrophysiological properties of the fibers between the previously reported conduction pathways from the left atrium to the right atrium and to the ventricle (left A-V ring pathways) and the ordinary atrial muscle, using perfused isolated rabbit hearts. Each fiber within these pathways showed action potential with a well-developed plateau phase. The plateau phase of these action potentials was distinctly shortened by an infusion of 1 x 10-6 g/ml of acetylcholine. When the heart was perfused by Tyrode solution with 15 mM KCl, the trans-membrane potential of the ordinary atrial muscle fiber showed a decrease of resting potential and of amplitude of action potential. The fibers within these pathways, however, were more resistant to the high potassium solution than the ordinary atrial fibers. A slow diastolic depolarization was observed in the fibers of the pathway when 1-isoproterenol (1 x 10-5 g/ml) was applied locally. These findings suggest that the fibers within the left A-B ring pathways possess similar electrophysiological properties to the specialized fibers in the atria.

Acetylcholine↗
PubMed1980

Polyamine and differentiation: induction of ornithine decarboxylase by parathyroid hormone is a good marker of differentiated chondrocytes.

The activity of ornithine decarboxylase (OD-Case:L-ornithine carboxy-lyase, EC 4.1.1.17) in rabbit costal chondrocytes in culture increased markedly after addition of parathyroid hormone (PTH), reaching a maximum 4 to 5 hr after PTH addition. The increase in ODCase activity was followed by increase in the intracellular concentrations of polyamines, especially putrescine, which increased in 6 hr to about 3-fold that of untreated cultures. The induction of ODCase by PTH was not observed in L, 3T3, HeLa, buffalo rat liver, or BHK cells. Retinyl acetate and retinoic acid both inhibited expression of the differentiated phenotype of chondrocytes by rabbit costal chondrocytes in culture within 3 days after their addition, as judged by morphological change and decrease in sulfate incorporation into glycosaminoglycans but did not inhibit cell proliferation. PTH could not induce an increase in ODCase in de-differentiated cells that had been pretreated with retinyl acetate or retinoic acid for 3 days. but 4 days after removal of the retinoids, these de-differentiated cells regained the ability to synthesize ODCase in response to PTH. These facts suggest that the induction of ODCase and the formation of putrescine by PTH are good markers of the differentiated phenotype of cultured chondrocytes.

Animals↗
PubMed1980

Rat brain enolase isozymes. Purification of three forms of enolase.

Three forms of rat brain enolase (Fletcher, L., Rider, C.C., & Taylor, C.B. (1976) Biochim. Biophys. Acta 452, 245-252), which were separable by DEAE-cellulose chromatography (referred as enolase I, enolase II, and enolase III in order of the elution), were purified with a high yield by use of column chromatographies of Sephadex G-150, Blue Sepharose CL-6B, and hydroxylapatite. About ten mg of each isozyme was obtained from 220 g of the brain with a yield of 30-50%. Sodium dodecyl sulfate gel electrophoresis of purified enolase I and enolase III showed single bands with relative mobilities corresponding to molecular weights of 49,000 (enolase I) or 46,000 (enolase III), and that of purified enolase II showed two bands corresponding to the above molecular sizes. Amino acid analysis of three forms of enolase revealed that the amount of each amino acid enolase II was midway between those of enolase I and enolase III. Antiserum to enolase I or enolase III was raised in New Zealand white rabbits. Results of immunochemical neutralization studies and immunolectrophoresis indicated that anti-enolase III was specific to the subunit of enolase III and reacted with enolase II and enolase III. However, anti-enolase I reacted not only with enolase I and enolase II, but also with enolase in various other tissues. These results support previous reports on crude preparations that enolase II was a hybrid molecule consisting of one enolase I subunit and one enolase III subunit.

Amino Acids↗
PubMed1980

Transfer factor from BCG-sensitized mice.

A mouse model was established for the study of transfer factor (TF). TF was extracted from the spleens of sensitized mice and examined for activity by the footpad test, which showed that mouse and human TF possessed similar properties. Parenteral administration of TF imparted to unsensitized mice immunologically specific, delayed type hypersensitivity within 24 hr. The magnitude of the response the recipients was proportional to the dose of TF. TF activity was relatively heat-stable, detectable in a fraction of molecular weight of ca 1,000 and apparently contained nucleic acids. Nude mice responded negatively to TF but following administration of viable naive spleen cells a positive response was observed, which suggests that the thymus plays an important role in the expression of TF phenomenon and that the target of TF is the T cells.

Animals↗
PubMed1980

Belt-like gap junctions in the ductuli efferentes of some mammalian testes.

Cellular junctions of the lining epithelium of the efferent ductules of the mouse, guinea pig, and human testes were examined by freeze-fracture. A belt-like gap juncion consists of a large aggregation of particles with a few fragments of the tight junctional strands and circumferentially occupies the adluminal area between the nonciliated cells. This type of gap junction appears to be one of the components of the junctional complexes in mammalian efferent ductules. Functional significance of the belt-like gap junction is discussed in the light of the findings.

Aged↗
PubMed1980

Affinity of young rat cerebral slices for bilirubin and some factors influencing its transfer to the slices.

Kinetics of bilirubin transfer to the cerebral slices prepared from 14- to 16-day-old Wistar rats and some factors influencing the transfer were investigated. Within the physiological pH range the rate of transfer was 3 times higher at pH 6.9 than at pH 7.4. The rate at pH 7.2 was a hyperbolic function of unbound bilirubin concentration [the maximum transfer rate (Vmax) = 1.5 mumol/20 min/g slice; the unbound bilirubin concentration to give half the Vmax value (Km) = 200 microM], while at pH 6.9 the saturation curve was biphasic with two sets of kinetic parameters (0.4 and 1.9 mumol/20 min/g slice for Vmax, and 18 and 480 microM for Km, respectively). The kinetics showed that at unbound bilirubin concentration lower than 0.1 mM the Km value at pH 6.9 was about one tenth of that at pH 7.2. The transfer process appeared to be independent of Na+ and was significantly stimulated by Tris+. The rate was reduced at low temperature, and inhibited by urea (competitive inhibition; the concentration to cause 50% inhibition = 100 mM) and sulfhydryl blocking reagents such as p-chloromercuribenzoate and N-ethylmaleimide.

Animals↗
PubMed1979

Morphogenesis of tight junctions in the peritoneal mesothelium of the mouse embryo.

The peritoneal mesothelium of mouse embryos (12 to 18 day of gestation) was studied by freeze-fracture and in sections in order to reveal the initial formation of the tight junctions. Freeze-fracture observations showed three types of tight junctions. Type I consists of belt-like meshworks of elevations on the P face and of shallow grooves on the E face. No tight junctional particle can be seen either on the elevations or in the grooves. Type II shows rows of discontinuous particles on the elevations on the P face. Type III consists of strands forming ridges on the P face. On the E face, the grooves of Type II and III appear to be narrower and sharper than those of Type I. Quantitatively, Type I junctions are most numerous during the early stages (day 12-13) of embryonic development, while Type III junctions become more common in the later stages, and are the only type seen by day 18. Observations on sections, however, fail to distinguish between the three types. The results suggest that an initial sign of tight junction formation is close apposition of the two cell membranes in the junctional domain, without tight junctional particles. Later, the particles appear to be incorporated in the tight junctions and the strands form by fusion of the particles.

Animals↗