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Biomedical subjects

M Furuya

Publications and source records attributed to M Furuya.

At least 163 records · Page 9Linked to original sources
PubMed1979

Effect of bradykinin to cyclic AMP levels and response of murine lymphocytes.

No information is available on the pharmacological effect of bradykinin to lymphocytes and immunological responses of them. In this study it was clarified that bradykinin as well as histamine elevated cyclic adenosine 3',5' monophosphate (cAMP) levels of murine splenic or lymph node lymphocytes and mature thymocytes (cortisone-resistant thymus), but did not increase cAMP levels of immature thymocytes as well as histamine. The increased cAMP ratios in T cell-enriched splenic lymphocytes by the impulse of bradykinin were higher than that in splenic and lymph node lymphoid cells by the stimulation of bradykinin. It was also demonstrated that bradykinin as well as histamine suppressed DNA synthesis by mitogenic (PHA-P, Con-A) stimulation of splenic lymphocytes, but not a effect to the response of lymphocytes by mitogenic (LPS) stimulation was observed. These facts suggest that bradykinin may play an important role in the regulation of immunologic lymphocyte responses.

Animals↗
PubMed1979

Protective immune response in mice immunized with antigens from Trypanosoma gambiense-infected mouse blood.

Immunogenicity and property of antigens obtained from Trypanosoma gambiense-infected mouse blood (IMP) were examined. A strong vaccine effect against intravenous challenges with 3 x10(3) parasites given on study day 3, 5, or 14 (day 0 = immunization) was observed in mice immunized with a combination of IMP (2 mg protein/mouse) and Freund's complete adjuvant (FCA). But when the challenge was given on day 21 or 30, per cent survival in mice dropped to the 20- and 40-per cent level, respectively. Among fractioned components of IMP, IMP-1, IMP-2, and imp-3, by gel filtration with Sephadex G-200, all of the mice immunized with IMP-1 antigen alone or together with FCA and challenged on day 5 were able to conquer intraperitoneal challenges with 1 x10(2) parasites. Mice immunized with IMP-2 or IMP-3 died within 6 days after challenge. Moreover, protection efficacy shown by IMP-1p (144,000 xg sediment of IMP-1) antigen in mice was similar to that by IMP and IMP-1 antigens. IMP-3 yielded a single precipitin line against mouse anti-IMP serum by Ouchterlony double diffusion method but this response was eliminated when the antiserum was absorbed by IMP-1p. No precipitin line was identified between mouse anti-IMP serum and IMP-1 or IMP-2. From electron microscopic observations, elements of IMP-1 and IMP-1p are possibly corresponded to the fragments of filopodia of the parasites.

Agglutination Tests↗
PubMed1979

In situ microspectrofluorometry of nuclear and kinetoplast DNA in Trypanosoma gambiense.

Using a spectrofluorometer with the Zeiss Universal Micro-Spectrophotometer 1 (UMSP 1), both nuclear and kinetoplast DNA (N-DNA and K-DNA) in the trypomastigote form of Trypanosoma gambiense (Strain Wellcome) were measured in situ without being extracted. As the fluorescent dye, ethidium bromide was preferably employed because there was a very marked increase in the ethidium fluorescence when the dye was intercalated between the base paires of the DNA helix. According to this method, it became possible to demonstrate the existence of double-stranded DNA in both nucleus and kinetoplast clearer than before.

DNA↗
PubMed1978

Phototactic Responses of Cell Population to Repeated Pulses of Yellow Light in a Phytoflagellate Cryptomonas sp.

Positive phototaxis in cell populations of a phytoflagellate Cryptomonas sp. was recorded photoelectrically when the duration and intensity of repeated pulses of monochromatic yellow light (570 nm) interspersed with darkness were varied. Irrespective of the duration of the light pulses, phototactic responses to repeated pulses were as great as those to continuous irradiation and were linearly dependent on the logarithm of total incident light energy when the dark interval was shorter than 60 milliseconds. Under these conditions, reciprocity between duration and intensity held well. In contrast, when the dark interval exceeded 250 milliseconds, the responses were remarkably reduced regardless of light duration and were not affected by increasing the intensity of actinic light pulses.The present results clearly indicate that continuous stimulation with actinic light is not essential for the maximum effect, but that the length of dark interval is crucial in phototactic response.

Journal Article↗
PubMed1975

Perithecial Formation in Gelasinospora reticulispora: IV. Action Spectra for the Photoinduction.

Action spectra for photoinduction of perithecia after different lengths of dark period were determined with apically growing mycelium of a sordariaceous fungus Gelasinospora reticulispora. When hyphae were exposed to monochromatic light in near ultraviolet and visible regions, reciprocity between intensity and exposure time was observed within the range of incident energy used. The resulting action spectrum determined after a dark period of 48 hours showed a peak at 460 nm with shoulders at 420 and 480 nm and another peak at 370 nm, indicating minima at 410, 430, and 470 nm. After 72 hours darkness the spectrum was very similar to the above, except that the major peak shifted to 450 nm and the near ultraviolet region was somewhat less effective. In both cases, wavelengths longer than 520 nm showed no effect.In addition, when irradiated with colored lamps, near ultraviolet light was relatively less effective after the 72-hour dark period than after the 48-hour dark period. The reason for this phenomenon is discussed.

Journal Article↗
PubMed1974

Phytochrome-dependent Reduction of Nicotinamide Nucleotides in the Mitochondrial Fraction Isolated from Etiolated Pea Epicotyls.

When mitochondria isolated from etiolated pea (Pisum sativum cv. Alaska) epicotyls were exposed briefly to red light, their ability to reduce exogenous NADP was enhanced. The red light effect was reversed by far red light. Photoreversible absorbance changes between 730 nm and 800 nm were spectrophotometrically detected in the purified mitochondria and its membrane fraction. The dehydrogenase activity in the mitochondria was heat-labile and was dependent on the presence of magnesium ion and appropriate substrates such as glucose 6-phosphate, isocitrate, pyruvate, 6-phosphogluconate, and succinate. The photoreversible effect was seen only for a few minutes after the irradiation, and was cancelled by hypotonic treatment or addition of Triton X-100. A similar but lesser effect was observed in the pea microsome fraction, whereas no photoreversible response was seen with a supernatant fraction resulting from centrifugation at 10(5)g for 30 minutes.

Journal Article↗
PubMed1973

A red-far red reversible effect on uptake of exogenous indoleacetic Acid in etiolated rice coleoptiles.

The uptake and accumulation of exogenous indoleacetic acid-(14)C by intact rice coleoptiles were examined. The absorption of exogenous indoleacetic acid was controlled by phytochrome, while the subsequent accumulation of this indoleacetic acid in various portions of the coleoptile was complex, and the effect of red light in this system was small compared to the alteration of the uptake of indoleacetic acid by red light. The absorption of indoleacetic acid exhibited two phases: the first occurring during the first 3-hour portion of the incubation was an inhibition, while the second was a promotive effect at about the 5th hour of incubation. Both of these effects were red, far redreversible, implicating phytochrome in this effect. Neither the destruction nor the immobilization of this exogenous indoleacetic acid apeared to be greatly affected by red light irradiation. The principal interaction between phytochrome and indoleacetic acid appears to occur during the absorption of exogenous indoleacetic acid. This effect may be related to the control by phytochrome of the amount of auxin which diffuses from coleoptile tips.

Journal Article↗
PubMed1972

Phytochrome action on the timing of cell division in adiantum gametophytes.

When filamentous protonemata of Adiantum capillus-veneris L. precultured under continuous red light were transferred to the dark, the apical cell divided about 24 to 36 hours thereafter. The time of the cell division was delayed for several hours by a brief exposure to far red light given before the dark incubation. The effect of far red light was reversed by a small dose of red light given immediately after the preceding far red light. The effects of red and far red light were repeatedly reversible, indicating that the timing of cell division was regulated by a phytochrome system. When a brief irradiation with blue light was given before the dark incubation, the cell division occurred after 17 to 26 hours in darkness. A similar red far red reversible effect was also observed in the timing of the blue light-induced cell division. Thus, the timing of cell division appeared to be controlled by phytochrome and a blue light-absorbing pigment.

Journal Article↗
PubMed1971

Phytochrome Action in Oryza sativa L: IV. Red and Far Red Reversible Effect on the Production of Ethylene in Excised Coleoptiles.

Excised apical segments of etiolated rice (Oryza sativa L.) coleoptiles produced ethylene. Increasing the number of cut sites per coleoptile increased the rate of ethylene formation. Ethylene produced by an etiolated-intact seedling in the dark was about a half of that by the excised coleoptile segment. Red light of low energy as well as of continuous irradiation inhibited the production of ethylene. The inhibition by a low energy dose of red light was partly relieved, if the red light was followed immediately by a small dose of far red light. The effect of red and far red light was repeatedly reversible, indicating that ethylene production was regulated by a phytochrome system. If the exposure to far red light was preceded by a period of darkness, this photoreversibility disappeared; 50% of the initial reversibility was lost within 5 hours. Applied ethylene (10 microliters per liter) significantly promoted the growth of intact coleoptiles of either totally etiolated or red light-treated seedlings, but had no effect on the excised apical segment of coleoptile.

Journal Article↗