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Biomedical subjects

H Matsubara

Publications and source records attributed to H Matsubara.

At least 253 records · Page 14Linked to original sources
PubMed1991

Effects of atrial natriuretic peptide infusion and its metabolism in patients with chronic renal failure.

Synthetic alpha-human atrial natriuretic peptide (hANP) was infused continuously at a rate of 80 ng/kg/min for 20 min into normal volunteers and patients with chronic renal failure (CRF) receiving hemodialysis. Blood pressure (BP) decreased significantly both in normals and in patients with CRF. The magnitude and the duration of the decrease, however, were greater in patients with CRF. The plasma aldosterone concentration (PAC) decreased significantly in normals and only minimally in patients with CRF. The half time (T1/2) of plasma hANP in patients with CRF (M +/- SE: 4.5 +/- 0.5 min) was longer than that in normals (1.8 +/- 0.2 min). Moreover, the metabolic clearance rate in patients with CRF (64 +/- 7 ml/kg/min) was less than in normals (150 +/- 20 ml/kg/min). Thus, the T1/2 in plasma of hANP in patients with CRF was noticeably longer than in a normal control group. These findings suggest that hANP suppresses PAC regardless of electrocyte imbalances and/or volume change induced by kidney dysfunction and that the kidney may be important in degrading hANP.

Adrenal Glands↗
PubMed1991

Regulation of atrial natriuretic hormone production by triiodothyronine in cultured rat atrial myocytes.

Since thyroid hormones have been reported to increase the synthesis of rat atrial natriuretic hormone and its mRNA accumulation, we further investigated the mechanism of stimulation of rANH synthesis by T3 using cultured rat atrial myocytes. T3 (10(-9)-10(-7) mol/l) increased cellular content and secretion into the medium of immunoreactive rANH in a dose-dependent manner. However, the ratio of secreted/cellular rANH was not altered by the addition of T3. Furthermore, in both cellular and secreted rANH, the larger molecular form (gamma-rANH) apparently predominated over the smaller one (alpha-rANH), and this profile was not influenced by T3 (10(-7) mol/l). Although T3 (10(-9)-10(-7) mol/l) also increased cellular rANH mRNA accumulation, the ratio of cellular rANH/rANH mRNA was not changed. Moreover, using actinomycin D, we found that T3 (10(-7) mol/l) did not affect the degradation of rANH mRNA. From these findings, we suggest that T3 has no specific effects on the translational and posttranslational processes and the release of rANH, but that T3 stimulates rANH synthesis in the pretranslational levels, probably in the transcriptional level of rANH gene.

Animals↗
PubMed1990

[Evaluation of modalities for recurrent breast cancer patients].

Of 342 breast cancer patients radically operated on in the Second Department of Surgery, School of Medicine, Chiba University during 1965-1988, treatment for 75 recurrent patients were evaluated by the initial modes of recurrence. The modes of recurrence were classified into distant metastases, local lymph node recurrence (axillary, parasternal and supraclavicular nodes) and chest wall recurrence according to the General Rules for Clinical and Pathological Recording of Breast Cancer. Of 75 recurrent patients, distant metastases were seen as common as 77.3%, followed by recurrences of local lymph nodes (14.7%) and chest wall (8.0%). The number of patients in each mode of recurrence increased in relation to increase in the size of tumor and the number of metastatic lymph nodes at the time of the first operation. Histologically, scirrhous carcinoma was most common in chest wall recurrence. 2-year disease-free survival rates of distant metastases, local lymph node recurrence and chest wall recurrence were 44.6%, 24.2% and 16.7%, respectively. 5-year survival of bone metastasis with chemo-endocrine therapy was as significantly favorable as 60%, compared to chemo- or radiotherapy alone (p less than 0.01). However, 5-year survival of lung metastasis with or without endocrine therapy revealed no significant difference. Local lymph node recurrence with the combination of resection, radio- and/or chemotherapy produced a trend toward showing more favorable survival than that without resection.

Bone Neoplasms↗
PubMed1990

Structure of the [2Fe-2S] ferredoxin I from the blue-green alga Aphanothece sacrum at 2.2 A resolution.

Crystals of a [2Fe-2S] ferredoxin (Fd) I with a relative molecular mass of 10,480 were obtained from the blue-green alga Aphanothece sacrum. Each asymmetric unit of the crystal contains four molecules. An electron density map calculated by the single isomorphous replacement method with the anomalous dispersion at 2.5 A resolution was refined by averaging the four molecules in the asymmetric unit. Positional and isotropic thermal parameters for the non-hydrogen atoms of the four molecules and 158 water molecules were refined to an R-factor (R = sigma[Fo-Fc[/sigma Fo) of 0.23 by the restrained least-squares method. The estimated root-mean-square (r.m.s.) error for the atomic positions is 0.3 A. The r.m.s. deviations of equivalent C alpha atoms of the asymmetric-unit molecules superposed by the least-squares method average 0.35 A. The Fd molecule has a structure like the beta-barrel in the molecule of the [2Fe-2S] Fd from Spirulina platensis. A [2Fe-2S] cluster is bonded covalently to the protein molecule by four Fe-S, in which three of the Fe-S bonds are in a loop segment from position 38 to 47. The hydrophobic core inside the beta-barrel is formed by seven conservative residues: Val15, Val18, Ile24, Leu51, Ile74, Ala79 and Ile87. The molecular surface around Tyr23, Tyr80 and the active center may interact with ferredoxin-NADP+ reductase. One of the two iron atoms of the [2Fe-2S] cluster should be more easily reduced than the other because of differences in the hydrogen-bonding scheme and the hydrophobicity around the atoms.

Amino Acid Sequence↗
PubMed1990

Expression of novel DNA-binding protein with zinc finger structure in various tumor cells.

We have isolated from B16 mouse melanoma cells a complementary DNA (Mel-18), whose deduced amino acid sequence possesses a characteristic zinc finger structure. Immunostaining with antibodies raised against partial Mel-18 peptide sequences demonstrated nuclear localization of the gene product. We have also demonstrated that this protein has DNA-binding capacity, and the zinc finger is responsible for the DNA binding. At the transcriptional level the Mel-18 mRNA was detected in all tumor cells examined as well as melanoma cells (ontogenically of neural origin) but was scarcely present in normal tissues except neural organs. The transcript is developmentally regulated. These data suggest that Mel-18 may play a role in transcriptional regulation and also in control of cell proliferation and/or neural cell development.

Amino Acid Sequence↗
PubMed1990

Tertiary structure of oxidized flavodoxin from an eukaryotic red alga Chondrus crispus at 2.35-A resolution. Localization of charged residues and implication for interaction with electron transfer partners.

The crystal structure of the oxidized form of a flavodoxin from an eukaryotic red alga, Chondrus crispus, has been determined by multiple isomorphous replacement and anomalous scattering methods. A model of the 173 residues and flavin mononucleotide (FMN) has been refined by a restrained least squares method to a crystallographic R-factor of 22.6% using 6236 reflections between 6.0 and 2.35 A with F greater than 3 sigma F. This molecule has a sheet consisting of five parallel beta-strands with two alpha-helices on one side of the sheet and three on the other side, and has a (beta alpha)5 structure. The molecule incorporates a substantial insertion in beta 5, as in Anacystis nidulans flavodoxin, which distinguishes these flavodoxins from the short-chain type. The isoalloxazine ring of FMN is sandwiched between the side chains of Trp-56 and Tyr-98, with its C-7 and C-8 methyl groups being exposed to solvent. The phosphate group of FMN is located at the N-terminal end of alpha 1, and forms extensive hydrogen bonds with the loop (T8-T13) between beta 1 and alpha 1 of the protein. Six of the total 11 lysine residues are clustered at the opposing face to the FMN-binding site, while about two-thirds of the total 35 acidic residues are located in the half of the molecule which includes the FMN-binding site. Such localization of charged residues produces a dipole within the molecule, which may be important in its recognition of the other proteins participating in electron transfer reactions.

Amino Acid Sequence↗
PubMed1990

An in vitro model for cyclosporin A-induced interference of intrathymic clonal elimination.

The effects of cyclosporin A (CsA) on influencing the intrathymic clonal deletion were investigated by using our established thymic stromal cell clone with capacities to express Ia antigens and to produce a unique T cell growth factor. The following were revealed: (a) T cell clone with a given specificity was killed on the Ia+ stromal cell monolayer in the presence of the relevant antigens, a process depending on T cell receptor (TCR) stimulation; and (b) CsA allowed the T cell clone to continuously proliferate even during TCR stimulation by virtue of the stromal cell-derived T cell growth factor. This paper describes an in vitro model of a mechanism by which CsA is responsible for the generation of normally "forbidden" T cell clones.

Animals↗
PubMed1990

Multiplicative effect of hyperpepsinogenemia I and non-secretor status on the risk of duodenal ulcer in siblings.

In a search for genetic markers of duodenal ulcer, serum pepsinogen I level, ABO blood groups and secretor status were determined in 89 siblings of 34 duodenal ulcer families. Duodenal ulcer patients were likely either to have hyperpepsinogenemia I or to be non-secretors on a familial basis, but not to have an increased frequency of blood group O. The frequency of duodenal ulcer in the siblings was highest in hyperpepsinogenemia I/non-secretor and lowest in normopepsinogenemia I/secretor. Therefore, the influence of two genes, hyperpepsinogenemia I and non-secretor, on the risk of duodenal ulcer is multiplicative. These results provide evidence on the hypothesis of polygenic inheritance of duodenal ulcer.

ABO Blood-Group System↗
PubMed1990

Simultaneous determination of glucose, ethanol and lactate in alcoholic beverages and serum by amperometric flow injection analysis with immobilized enzyme reactors.

Glucose, ethanol and lactate were determined simultaneously in a flow injection system by using a parallel configuration of immobilized enzyme reactors. Hydrogen peroxide produced was monitored amperometrically at the potential of +0.65 V vs. Ag/AgCl. Linear relations between sensor responses and each species were observed in the ranges of 0.02-10 mM (glucose), 5 x 10(-4)-0.1% (v/v) (ethanol) and 0.005-1 mM (lactate) with correlation coefficients larger than 0.999 for each species. The relative standard deviations for 10 successive injections were 1.4, 0.5 and 1.1% for glucose (1 mM), ethanol (5 x 10(-3)% (v/v] and lactate (0.05 mM), respectively. Analysis of serum samples was performed with urate-eliminating reactors which were set just before each immobilized enzyme reactor. Interference of ascorbate in a serum sample was completely eliminated by using an ascorbate-eliminating reactor which was set before the sample injection valve. Application of the system to alcoholic beverages and control serum was described and the results were compared with those of free enzymatic, spectrophotometric analysis (F-kit or C-test method).

Alcoholic Beverages↗
PubMed1990

T cell clones are killed by a thymic stromal cell monolayer following stimulation of T cell receptor with antigen and/or H-2 molecules on the monolayer.

A thymic stromal cell clone, MRL104.8a, expressed class I and class II H-2k antigens after exposure to gamma-interferon (gamma-IFN) and produced thymic stroma-derived T cell growth factor (TSTGF) irrespective of gamma-IFN exposure. Culturing the keyhole limpet hemocyanin (KLH)-specific, I-Ek-restricted 9-16 helper T cell (Th) clone on an Ia (I-Ak and I-Ek)-expressing MRL 104.8a monolayer induced potent proliferation of the 9-16 cells by virtue of the TSTGF produced by the monolayer. In contrast, the addition of KLH to cultures resulted in lethal growth inhibition of the 9-16 Th clone. Such a phenomenon was also observed for various Th as well as cytotoxic T lymphocyte (CTL) clones, and the following were revealed: (i) the growth of the ovalbumin (OVA)-or bovine thyroglobulin (BTg)-specific Th clone on the la-expressing MRL 104.8a monolayer was also inhibited by addition of the relevant antigen. The fact that these Th clones required antigen-presenting cells (APC) capable of processing antigen for the recognition of the respective target antigen suggested the potential of MRL 104.8a cells for antigen-processing; (ii) the lethal growth inhibition of KLH-specific, I-Ak (23-1-8)- or I-Ek (9-16)-restricted Th clone was prevented selectively by anti-I-Ak or anti-I-Ek antibody respectively; (iii) the I-Ek-alloreactive Th clone (2-13) was supported for its growth on a gamma-IFN-unexposed MRL 104.8a monolayer, whereas this clone was killed on an I-Ek-expressing monolayer; and (iv) when I-Ak-reactive CTL clones were cultured on an Ia- or Ia+ monolayer, CTL clones failed to exhibit cytotoxic effect on either the Ia- or the Ia+ monolayer, but were conversely killed by the Ia+ monolayer. Its killing was also prevented by an antibody which inhibits the recognition of Ia antigen on the monolayer by CTL clones.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Site-directedly mutated human cytochrome c which retains heme c via only one thioether bond.

Although Cys-14 (human numbering) of cytochrome c was conserved during its molecular evolution and it is supposed to be essential for most cytochromes c to retain heme c via two thioether bonds, a site-directedly mutated human cytochrome c which has an alanine residue at this position and only one thioether bond through Cys-17 turns out to be functional. This shows that Cys-14 is not essential. The absorption spectrum of the atypical cytochrome c is red shifted, and similar to those of Euglena and Crithidia cytochromes c, which also have only one thioether bond [Pettigrew, G.W., Leaver, J.L., Meyer, T.E., & Ryle, A.P. (1975) Biochem. J. 147, 291-302].

Amino Acid Sequence↗
PubMed1990

Two distinct ferredoxins from Rhodobacter capsulatus: complete amino acid sequences and molecular evolution.

Two distinct ferredoxins were purified from Rhodobacter capsulatus SB1003. Their complete amino acid sequences were determined by a combination of protease digestion, BrCN cleavage and Edman degradation. Ferredoxins I and II were composed of 64 and 111 amino acids, respectively, with molecular weights of 6,728 and 12,549 excluding iron and sulfur atoms. Both contained two Cys clusters in their amino acid sequences. The first cluster of ferredoxin I and the second cluster of ferredoxin II had a sequence, CxxCxxCxxxCP, in common with the ferredoxins found in Clostridia. The second cluster of ferredoxin I had a sequence, CxxCxxxxxxxxCxxxCM, with extra amino acids between the second and third Cys, which has been reported for other photosynthetic bacterial ferredoxins and putative ferredoxins (nif-gene products) from nitrogen-fixing bacteria, and with a unique occurrence of Met. The first cluster of ferredoxin II had a CxxCxxxxCxxxCP sequence, with two additional amino acids between the second and third Cys, a characteristics feature of Azotobacter-[3Fe-4S] [4Fe-4S]-ferredoxin. Ferredoxin II was also similar to Azotobacter-type ferredoxins with an extended carboxyl (C-) terminal sequence compared to the common Clostridium-type. The evolutionary relationship of the two together with a putative one recently found to be encoded in nifENXQ region in this bacterium [Moreno-Vivian et al. (1989) J. Bacteriol. 171, 2591-2598] is discussed.

Amino Acid Sequence↗
PubMed1990

Replacement of putative axial ligands of heme iron in yeast cytochrome c1 by site-directed mutagenesis.

The His-44 and Met-164 residues of yeast cytochrome c1 are evolutionally conserved and regarded as heme axial ligands bonding to the fifth and sixth coordination sites of the heme iron, which is directly involved in the electron transfer mechanism. Oligonucleotide-directed mutagenesis was used to generate mutant forms of cytochrome c1 of yeast having amino acid replacements of the putative axial ligands of the heme iron. When a cytochrome c1-deficiency yeast strain was transformed with a gene encoding the Phe-44, Tyr-44, Leu-164, or Lys-164 protein, none of these transformants could grow on the non-fermentable carbon source. These results suggest that the His-44 and Met-164 residues have a critical role in the function of cytochrome c1 in vivo, most probably as axial ligands of the heme iron. Further analysis revealed that the mutant yeast cells with the Phe-44, Tyr-44, or Leu-164 protein lacked the characteristic difference spectroscopic signal of cytochrome c1. However, in the Lys-164 mutant cells, partial recovery of the cytochrome c1 signal was observed. Moreover, the Lys-164 protein retained a low but significant level of succinate-cytochrome c reductase activity in vitro. The possibility that the nitrogen of Lys-164 served as the sixth heme ligand is discussed in comparison with cytochrome f of a photosynthetic electron-transfer complex, in which lysine has been proposed to be the sixth ligand.

Base Sequence↗
PubMed1990

Clinical factors relating to the positive glycerol test for Ménière's disease.

In order to investigate the clinical factors relating to positive glycerol tests, 51 patients with Ménière's disease were subjected to a complete battery of audiometric examinations, including the short increment sensitivity index, Bekesy, alternate binaural loudness balance, speech discrimination and pure-tone audiometry tests, both before and after glycerol ingestion. The correlation between positive glycerol tests and vestibular response, cochlear symptoms, age at onset and disease duration was investigated. High ratios of positive tests were obtained in the following categories of patients with Ménière's disease: elderly patients with vertiginous attacks; patients with high-level hearing loss; nystagmus patients, and patients with fluctuating hearing loss.

Adult↗
PubMed1990

Changes of atrial natriuretic peptide and its messenger RNA with development and regression of cardiac hypertrophy in renovascular hypertensive rats.

We assessed the changes in atrial natriuretic peptide (ANP) and its messenger RNA (mRNA) levels in atria and ventricles in relation to hemodynamic factors during antihypertensive treatments in two-kidney, one-clip renovascular hypertensive rats (RHRs). Hypertension of 10-week duration caused a twofold increase in the left ventricular weight/body weight ratio, a significant increase in left ventricular end-diastolic pressure, and an eightfold increase in left ventricular ANP mRNA levels in RHRs, as compared with the levels in control rats. Uninephrectomy or 4 weeks of treatment with the converting enzyme inhibitor enalapril reduced the blood pressure to the control level, with the complete reversal of left ventricular hypertrophy, left ventricular end-diastolic pressure, and ANP mRNA levels. Four weeks of treatment with the arterial vasodilator hydralazine significantly, but not completely, reduced the high blood pressure, but it did not influence left ventricular hypertrophy, end-diastolic pressure, and ANP mRNA levels. The increased ANP synthesis observed in the right ventricles of RHRs also reverted to the control level by uninephrectomy or enalapril treatment, but not by hydralazine, with a time course similar to that of left ventricular ANP. In addition, uninephrectomy caused the left and right ventricular ANP and ANP mRNA levels of RHRs to fall to the levels of control rats as early as 1 week, despite persistent left ventricular hypertrophy.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗