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Biomedical subjects

M Furuya

Publications and source records attributed to M Furuya.

At least 91 records · Page 5Linked to original sources
PubMed1993

Nonlinear identification of the PCO2 control system in man.

Two approaches to identification of the PCO2 system in man are described. The first uses a nonlinear 'black box' NARMAX identification package, while the second method uses a structured two-compartment Belville model. The data were obtained from volunteers breathing either room air or a controlled gas mixture, controlled via a pseudorandom M-sequence. Measurements were made of respiratory gas flow and PCO2 content of inspired and expired gases. The identification results indicate that a low-order dynamic model with nonlinear polynomial expansion gave the best fit to the data. In contrast, the Belville model gave best results with a two-compartment linear model, mainly because of difficulties in the optimisation routines when the Belville model was not linear. Thus, modern systemic methods of excitation and identification appear to be appropriate for modelling this respiratory subsystem of humans.

Adult↗
PubMed1993

Identification of photo-inactive phytochrome A in etiolated seedlings and photo-active phytochrome B in green leaves of the aurea mutant of tomato.

The contents of spectrophotometrically measurable phytochrome A (PhyA) and phytochrome B (PhyB) and the corresponding immunochemically detectable apoproteins (PHYA and PHYB) were examined in dark- and light-grown tissues of the aurea mutant of tomato and its wild-type (WT). The amount of PHYA in etiolated aurea seedlings was found to be about 20% of that in the WT; this PHYA showed no photo-reversible changes in absorbance, no downregulation of the level of PHYA in light-grown seedlings, and no differential proteolysis of Pr and Pfr species in vitro which was seen in the case of the WT. By contrast, the amount of PHYB in aurea seedlings was not significantly different from that in WT seedlings. Phytochrome isolated from green leaves of the aurea mutant and purified by ion-exchange chromatography showed a red/far-red reversible spectral change, and its elution profile during chromatography was essentially similar to that of PHYB. The results indicate that aurea is a mutant that is deficient in photoactive PhyA at the etiolated stage, when it contains a spectrally inactive PHYA. However, the mutant contains spectrally active PhyB in its green tissue as does the WT.

Enzyme Activation↗
PubMed1993

Mutations in the gene for the red/far-red light receptor phytochrome B alter cell elongation and physiological responses throughout Arabidopsis development.

Phytochromes are a family of plant photoreceptors that mediate physiological and developmental responses to changes in red and far-red light conditions. In Arabidopsis, there are genes for at least five phytochrome proteins. These photoreceptors control such responses as germination, stem elongation, flowering, gene expression, and chloroplast and leaf development. However, it is not known which red light responses are controlled by which phytochrome species, or whether the different phytochromes have overlapping functions. We report here that previously described hy3 mutants have mutations in the gene coding for phytochrome B (PhyB). These are the first mutations shown to lie in a plant photoreceptor gene. A number of tissues are abnormally elongated in the hy3(phyB) mutants, including hypocotyls, stems, petioles, and root hairs. In addition, the mutants flower earlier than the wild type, and they accumulate less chlorophyll. PhyB thus controls Arabidopsis development at numerous stages and in multiple tissues.

Amino Acid Sequence↗
PubMed1993

Syntheses and biological activities of selenium analogs of alpha-rat atrial natriuretic peptide.

alpha-Rat atrial natriuretic peptide (7--28) (rANP (7--28)) and a series of its analogs in which half cystine residue(s) were substituted with half selenocystine residue(s) were synthesized by using the Fmoc-based solid-phase method followed by cyclization by means of dimethylsulfoxide (DMSO)-trifluoroacetic acid (TFA) oxidation. These analogs possess comparable activities in both receptor binding and cGMP accumulation in rat vascular smooth muscle cells to those of rAMP (7--28).

Amino Acid Sequence↗
PubMed1993

[Effect of carperitide (alpha-human atrial natriuretic polypeptide) on the cardiovascular system in experimental animals].

The cardiovascular and diuretic actions of carperitide were studied in experimental animals. Carperitide relaxed various canine arteries and veins that were contracted by high K+ or norepinephrine. Carperitide stimulated particulate guanylate cyclase from rat thoracic aortas. Carperitide had almost no effect on coronary perfusion pressure or heart rate, but caused a slight decrease in contractile force in isolated guinea pig hearts. Carperitide tended to decrease isoproterenol-induced renin release from isolated rat kidney slices and elicited decreases in angiotensin II-induced aldosterone release from bovine zona glomerulosa cells. Intravenous injection of carperitide elicited decreases in arterial blood pressure and total peripheral resistance in the anesthetized and conscious dogs. Carperitide also elicited transient increases in cardiac output and coronary blood flow followed by slight decreases in them. Intravenous infusion of carperitide elicited decreases in pulmonary capillary wedge pressure, pulmonary pressure and right atrial pressure in association with elevating plasma carperitide (ANP like immuno-reactivity) level in dogs with heart failure induced by coronary artery occlusion and saline loading. These results suggest that carperitide decreases both preload and afterload and can improve the untoward hemodynamic alterations in animals with acute experimental heart failure.

Animals↗
PubMed1993

Molecular karyotype characterization of Leishmania panamensis, Leishmania mexicana, and Leishmania major-like parasites: agents of cutaneous leishmaniasis in Ecuador.

Molecular karyotypes of Leishmania isolates from patients with cutaneous leishmaniasis in Ecuador were analyzed by pulsed-field gel electrophoresis (PFGE) and Southern blot hybridization. The DNA karyotypes of L. major-like parasites were similar between two human isolates from a lowland coastal and a highland Andean region, but were apparently different from those of eleven World Health Organization reference strains including L. major. The smallest chromosome of 240 kilobases in L. major-like parasites was found to belong to the 715-class of small linear chromosomal DNAs, which have been shown to appear in some lines of Leishmania. Chromosome banding patterns of L. mexicana isolates exhibited a novel, ordered, chromosomal ladder, and were identical among four human isolates and one canine isolate from a restricted geographic region in the Andes. On the other hand, minor chromosome size polymorphisms were observed among three L. panamensis isolates from different endemic regions near the Pacific Coast. Chromosomal locations of dihydrofolate reductase-thymidylate synthetase and P-glycoprotein genes revealed further differences in chromosomal organizations among these Leishmania species in Ecuador. These results indicate that karyotype analysis by PFGE is useful for epidemiologic studies of leishmaniasis in Ecuador.

Animals↗
PubMed1992

Structural requirements of C-type natriuretic peptide for elevation of cyclic GMP in cultured vascular smooth muscle cells.

C-type natriuretic peptide (CNP), which was recently found to be a selective ligand for one of the two known natriuretic peptide receptor guanylyl cyclases (NPR-B), potently stimulates cGMP production in cultured rat vascular smooth muscle cells (VSMC) and exerts potent antiproliferative effects on the cells. To investigate the structural requirements of CNP for stimulation of cGMP accumulation via NPR-B, we prepared CNP analogs and tested them on cultured rat VSMC. Our results indicate that only the ring portion of CNP with a disulfide bond (CNP(6-22)) participates in stimulation of cGMP accumulation, especially the sequence Leu9-Lys10-Leu11 in the ring portion executes essential roles for both elevation of cGMP and selectivity of the ligand for NPR-B. We also found a good correlation between the activities of the CNP analogs for stimulation of cGMP accumulation and inhibition of DNA synthesis.

Amino Acid Sequence↗
PubMed1992

Serine-to-alanine substitutions at the amino-terminal region of phytochrome A result in an increase in biological activity.

We have used a tobacco transgenic plant system to assay the structure/function relationship of phytochrome A (phyA), a plant photoreceptor. The amino terminus of phyA from different plant species is very rich in serine residues. To investigate whether these serine residues are required for phytochrome function, the first 10 serine codons encoding amino acid residues 2-4, 10-14, 19, and 20 in the amino-terminal domain of the rice phyA gene (phyA) were changed to alanine codons. The mutant (S/A phyA), as well as the wild-type phyA cDNA, was placed under the control of the 35S promoter, and the chimeric genes were transferred into the tobacco genome by Agrobacterium-mediated transformation. Transgenic tobacco plants expressing either wild-type or S/A phyA showed similar phenotypic alterations, including dwarfism and dark-green leaves. However, hypocotyl elongation experiments revealed that transgenic seedlings expressing S/A phyA showed a higher amplitude of the red light response with respect to the inhibition of hypocotyl elongation. The observed difference is not correlated with expression levels of the transgene. The chromophore is attached to the mutant phyA apoprotein (PHY A), and the mutant photoreceptor is photoreversible, giving a difference spectrum indistinguishable from that of the rice phyA. Our results indicate that the S/A mutant has a higher biological activity as compared with the wild-type rice phyA.

Alanine↗
PubMed1992

Auxin Redistribution during First Positive Phototropism in Corn Coleoptiles : Microtubule Reorientation and the Cholodny-Went Theory.

In red-light grown corn (Zea mays L. cv Brio42.HT) coleoptiles, cortical microtubules adjacent to the outer cell wall of the outer epidermis reorient from transverse to longitudinal in response to auxin depletion and after phototropic stimulation in the lighted side of the coleoptile. This was used as an in situ assay of cellular auxin concentration. The fluence-response relation for the blue light-induced reorientation is compared with that for first positive phototropism and the dose-response relationship for the auxin-dependent reorientation. The result supports the theory by Cholodny and Went, claiming that phototropic stimulation results in auxin displacement across the coleoptile. In terms of microtubule orientation, this displacement becomes even more pronounced after preirradiation with a weak blue light pulse from above.

Journal Article↗
PubMed1992

Detection of antibodies against streptococcal peptidoglycan and the peptide subunit (synthetic tetra-D-alanyl-bovine serum albumin complex) in rheumatic-diseases.

Serum antibodies reactive with streptococcal cell wall peptidoglycan (PG) and its peptide subunit (synthetic tetra-D-alanine) were measured by enzyme-linked immunosorbent assay (ELISA) in patients with rheumatoid arthritis (RA), juvenile rheumatoid arthritis (JRA), osteoarthritis and acute rheumatic fever (RF) compared with healthy subjects. Using 'checkerboard' titrations, anti-PG antibody in human serum was detected at a concentration of PG antigen at 10 micrograms per well with serum dilutions of 1:1,000. For measurement of anti-tetra-D-alanine antibody, the antigen, (D-Ala4)31 was used at 0.5 micrograms per well and sera were diluted to 1:200. When the IgG antibody levels to the PG and the tetra-D-alanine of the sera of patients with RA, JRA and RF were compared with sera from healthy subjects, the sera of the patients had significantly higher levels than did healthy subjects. Antibody that reacted with the PG in serum was absorbed with purified group-specific C-carbohydrate (A-CHO), but A-CHO was not capable of absorbing anti-(D-Ala4)31 antibodies. Therefore, the peptide subunit should be used as antigen in order to measure the specific antibody to PG. Both anti-PG and anti-tetra-D-alanine antibody in human sera primarily belonged to the IgG2 subclass.

Adolescent↗
PubMed1992

Xeroderma pigmentosum variant associated with multiple skin cancers and a lung cancer.

A 65-year-old Japanese man with a xeroderma pigmentosum (XP) variant, XP127TO, is described. The XP127TO skin fibroblasts exhibited the typical XP variant characteristics of a 1.5-fold higher sensitivity than normal cells to the lethal effect of 254 nm ultraviolet (UV) light and the normal level of unscheduled DNA synthesis induced by 254 nm UV. Caffeine dose-dependently increased the cytotoxic effect of 254 nm UV on XP127TO cells. Clinically, the patient developed not only 3 cutaneous squamous cell carcinomas on sun-exposed areas but also an adenocarcinoma of the upper lobe of the right lung. A review of the 14 documented Japanese XP patients with nonskin malignancies indicates that the incidence of nonskin malignancy in XP patients is much lower than that of skin cancer in XP but higher than that in the general population.

Adenocarcinoma, Papillary↗
PubMed1992

The cucumber long hypocotyl mutant lacks a light-stable PHYB-like phytochrome.

A novel cDNA sequence homologous to a phytochrome B (phyB) gene that was isolated in a library from tobacco tissue has been used in an Escherichia coli expression system to raise anti-phytochrome B (anti-PHYB) polypeptide-specific monoclonal antibodies. The specificity of these antibodies has been tested by cross-reactivity against purified pea light-labile type 1 and light-stable type 2 phytochromes, with some antibodies reacting with the type 2 and none with the type 1 phytochromes. One such antibody, monoclonal mAT1, has been employed to analyze the phytochrome molecular species present in a photomorphogenic long hypocotyl (lh) mutant of cucumber. The results indicated that the mutant contains wild-type levels of the light-labile type 1 phytochrome polypeptide (PHYA), which has an apparent molecular mass of approximately 120 kD, but shows less than 1% (detection limit) of a light-stable polypeptide recognized by mAT1 in wild-type seedlings. This protein, not detectable in the lh mutant, has the properties of light-stable type 2 phytochrome, has an apparent molecular mass of 116 to 117 kD, and remains at constant levels under continuous low-fluence-rate red light. Therefore, we conclude that the lh mutant lacks at least one type 2 phytochrome-like polypeptide, most probably a phyB gene product. The correlation between the lack of this protein and the deficiency or absence of physiological responses to a light-stable phytochrome species in this mutant helps to identify the physiological roles played by the products of different subfamilies within the phytochrome gene family.

Antibodies, Monoclonal↗
PubMed1991

In vitro assembly of apophytochrome and apophytochrome deletion mutants expressed in yeast with phycocyanobilin.

Recombinant pea type I phytochrome apoprotein expressed in yeast is shown to assemble in vitro with phycocyanobilin to produce a photoreversible phytochrome-like adduct. As an initial investigation of the amino acid sequence requirements for chromophore incorporation, three phyA gene product deletion mutants were produced in yeast. Truncation of the N-terminal tail to residue 46 demonstrates that this region is not critical to bilin attachment, but a deletion mutant lacking 222 amino acids from the N terminus failed to yield holophytochrome in vitro, under the same conditions. A mutant comprising a deletion of the C terminus to residue 548 showed bilin incorporation and red/far-red photoreversibility, indicating that bilin-apophytochrome assembly still occurred even when the entire C-terminal domain was truncated.

Apoproteins↗
PubMed1991

Pharmacological activities of brain natriuretic peptides of human, porcine and rat origin.

The pharmacological activities of synthetic mammalian brain natriuretic peptides (BNP) from the human, pig and rat were examined in rats. These peptides all elicited diuresis and hypotension, relaxed isolated rat aorta, augmented cyclic GMP concentration in cultured rat vascular smooth muscle cells, and bound to the cells with a high affinity. Pig and rat BNPs were as active as atrial natriuretic peptides from the human and the rat (alpha-hANP and alpha-rANP) for the diuretic and hypotensive effects as well as for cyclic GMP augmentation, while human BNP was about 10 times less potent. Rat BNP was not as active as the other peptides in competing with the binding of [125I]alpha-hANP to rat vascular smooth muscle cells. Thus, the BNPs did not have identical pharmacological profiles although the potencies of the peptides for cyclic GMP augmentation correlated well to those for vasorelaxation.

Amino Acid Sequence↗
PubMed1991

C-type natriuretic peptide is a growth inhibitor of rat vascular smooth muscle cells.

C-type natriuretic peptide (CNP) which potently stimulates particulate guanylate cyclase activity in cultured rat vascular smooth muscle cells (VSMC) inhibited serum-induced DNA synthesis of the cells 10-fold more effectively than alpha-human atrial natriuretic peptide (alpha-hANP). The inhibitory effect of CNP was mimicked by 8-bromo-cGMP. The proliferation of VSMC was also suppressed by CNP more potently than alpha-hANP, while the peptide was less active for cGMP augmentation and for vasorelaxation than alpha-hANP in isolated rat aorta. These results suggest that CNP may be a growth regulating factor of VSMC rather than a vasodilator.

Animals↗
PubMed1991

Rice type I phytochrome regulates hypocotyl elongation in transgenic tobacco seedlings.

We have examined the biological activity of rice type I phytochrome (PI) in transgenic tobacco seedlings. The progeny of four independent transformants that expressed the rice PI gene segregated 3:1 for shorter hypocotyl length under dim white light (0.04 W/m2). By contrast, this phenotype was not observed either in the dark or under white light at higher intensity (6.0 W/m2). This suggests that the phenotype is dependent not only on light but also on light intensity. The increased light sensitivity cosegregated with the kanamycin-resistance marker as well as with the rice PI polypeptides, indicating that this phenotype is directly related to the expression of the transgene. The transgenic plants showing short hypocotyls exhibited a reduced growth rate throughout the elongation period, and the resulting shorter hypocotyl length was attributable to shorter epidermal cell length but not to reduced cell number. Furthermore, successive pulse irradiations with red light elicited short hypocotyls similar to those obtained under dim white light, and the effect was reversed by immediate far-red light treatment, providing a direct indication that the phenotype is caused by biologically active rice PI. Therefore, the far-red-absorbing form of the introduced rice PI appears to regulate the hypocotyl length of the transgenic tobacco plants through endogenous signal-transduction pathways. This assay system will be a powerful tool for testing the biological activity of introduced phytochrome molecules.

Journal Article↗
PubMed1991

Distribution of type I phytochrome (phyA) RNA1 and RNA2 in etiolated pea seedlings.

Four-day-old etiolated pea seedlings were divided into 11 parts along the axis, from which poly(A)+ RNA and DNA were extracted. Using a slot-blot hybridization assay, the abundance of pea type I phytochrome (phyA) poly(A)+ RNA was measured in each portion of the etiolated pea seedling. For the quantification of the phyA RNA, pea phyA RNA synthesized in vitro was used as an RNA standard. The hook region contained the highest abundance of phyA RNA (approximately 0.3 ng phyA RNA per microgram DNA) in the etiolated seedling. Two mRNAs of different length (the shorter designated as RNA1 and the longer RNA2) are produced in detectable amounts from single pea phyA in the etiolated seedling; the ratio of the abundance of phyA RNA1 to phyA RNA2 was determined in each of the 11 parts by a primer extension assay. The abundance of phyA RNA1 in the plumule and hook regions was 3-5-fold higher than that of RNA2, whereas the ratio of their abundance was approximately unity in other regions. A time course study of the abundance of both RNAs was carried out during the imbibition of seeds and indicated that the accumulation of phyA RNA1 occurred more rapidly in the cotyledons than that of RNA2 during the first day of imbibition, whereas the accumulation of phyA RNA2 increased rapidly during the second day and became as high as that of phyA RNA1 by the third day.

Base Sequence↗