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Biomedical subjects

H Murakami

Publications and source records attributed to H Murakami.

At least 685 records · Page 38Linked to original sources
PubMed1986

Purification and properties of a diheme cytochrome b561 of the Escherichia coli respiratory chain.

A new b-type cytochrome, cytochrome b561 (Murakami, H., Kita, K., Oya, H., and Anraku, Y. (1984) Mol. Gen. Genet. 196, 1-5) was purified to near homogeneity from the cytochrome b561-amplified Escherichia coli K12 strain HM204/pAM5029. The purified cytochrome b561 was a single polypeptide with a molecular weight of 18,000, determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Its isoelectric point was determined to be 9.6. The difference spectrum of the cytochrome at 77 K shows a major alpha-absorption peak at 561 nm and a minor peak at 555 nm. The absolute spectrum at room temperature of the oxidized form of the cytochrome had an absorption peak at 414 nm, and that of the reduced form had peaks at 562, 530, and 428 nm. The oxidation-reduction potential of the cytochrome was estimated to be +20 mV. The cytochrome contained 91.2 nmol of heme/mg of protein, showing that it was a cytoplasmic membrane-bound, b-type diheme cytochrome.

Cytochrome b Group↗
PubMed1986

Suppression of immunoglobulin synthesis by activated B cells in chronic active liver diseases and primary biliary cirrhosis.

We investigated the suppressor function of peripheral blood B cells from patients with chronic active liver diseases (CALD) and primary biliary cirrhosis (PBC). Suppressor cells were generated by preincubation of B cells with protein A, and suppressive effects were evaluated by inhibition of pokeweed mitogen-induced immunoglobulin (Ig) synthesis of normal peripheral blood lymphocytes (PBL) in second-set cultures. The mean percent suppressions for IgG and IgM synthesis of 12 HBsAg-negative patients with CALD, who were not on prednisone therapy, were lower (p less than 0.01, respectively) than those of controls. B cells from 6 HBsAg-positive patients with CALD also showed less suppression of IgG and IgM synthesis (p less than 0.01, respectively). Moreover the suppression for IgG and IgM in 7 patients with PBC were decreased (p less than 0.01, respectively). There was an inverse correlation between serum gammaglobulin level and percent suppression for IgG synthesis by protein A-activated B cells of patients with CALD (r = -0.50, p less than 0.05). Further studies demonstrated that protein A-activated B cells were capable of activating the suppressor function of T cells, which could then act to inhibit further B cell differentiation. These results suggest an aberrance of a feedback mechanism that is likely to regulate Ig synthesis in patients with CALD and PBC.

Adult↗
PubMed1986

Reduced nerve blood flow in edematous neuropathies: a biomechanical mechanism.

Reduced nerve blood flow has been reported in two experimental neuropathies in which edema is an early and significant finding. While the mechanisms of fluid accumulation differed, both resulted in increases of endoneurial fluid pressure up to five times the normal value. As increased endoneurial fluid distends the nerve, the perineurial sheath resists expansion and endoneurial fluid pressure increases. The semirigid perineurium is also a conduit for regional nutritive vessels which provide the greater part of peripheral nerve blood flow. Engineering structural analysis of blood vessels entering the endoneurium suggests that moderate elevations in endoneurial fluid pressure can deform cylindrical vessels in the perineurium into elliptical shapes by creating circumferential elongation and longitudinal compression of the vessels which reduce the cross-sectional area of the lumen. We propose that the pathogenesis of reduced nerve blood flow in edematous neuropathies is linked to the unique structure of the peripheral nerve perineurium and the nerve vasculature, in particular to deformation of anastomotic vessels traversing it.

Animals↗
PubMed1986

The relaxing effect of SKF 38393 on the catch contraction of Mytilus smooth muscle.

The relaxing effect of SKF 38393 on the catch contraction in the anterior byssus retractor muscle (ABRM) of Mytilus and the effect of SKF 38393 on the cyclic AMP (cAMP) levels in the ABRM were investigated. The catch contraction was relaxed by SKF 38393 in a dose-dependent manner. The dose-response curves of SKF 38393 were shifted in parallel to the right by butaclamol (3 X 10(-6) and 6 X 10(-6) M) and haloperidol (3 X 10(-6) and 3 X 10(-5) M). Their pA2 values were 5.69 +/- 0.05 and 5.80 +/- 0.07. The cAMP levels in the ABRM were not altered by SKF 38393 at a concentration (10(-5) M) sufficient to relax. These findings indicate that the dopamine receptors of the ABRM are D-1 like receptors but somewhat different from those of the vertebrates.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1986

HO-323, a human B-lymphoblastoid cell line useful for making human-human hybridomas.

A 6-thioguanine-resistant human B-lymphoblastoid cell line, HO-323, was isolated for making human-human hybridomas with high efficiency. Fusions with peripheral blood lymphocytes of systemic lupus erythematosus (SLE) patients and lymphocytes isolated from lymph nodes of lung and breast cancer patients yield constantly more than one hybridoma clones per 10(5) HO-323 cells plated. HO323 cells also fused with lymphocytes from normal peripheral blood to give hybridomas in the same efficiency. The HO-323 cells were diploid with 46 chromosomes and non-secretors of immunoglobulins. This parent cells doubled every 15 hr and could proliferate in serum-containing medium, even if they were plated at low cell density of less than 10(3) cells/ml. The cells could grow in serum-free medium as well as in serum-containing medium, and the resultant human-human hybridomas could also grow in the same media.

B-Lymphocytes↗
PubMed1986

Expression of rat NADPH-cytochrome P-450 reductase cDNA in Saccharomyces cerevisiae.

A full-length cDNA for rat NADPH-cytochrome P-450 reductase was cloned by the procedure of Okayama and Berg (1982) from hepatic poly(A)RNA prepared from phenobarbital-induced rats. Both cDNA and amino acid sequences agreed with the sequences reported by Porter and Kasper (1985) except for four single base differences. Three expression plasmids were constructed by insertion of the reductase cDNA between yeast alcohol dehydrogenase I (ADH) promoter and terminator regions. Plasmids pARF1 and pTRF2 were constructed with slightly different lengths between the ADH promoter and the initiation codon; on introduction into Saccharomyces cerevisiae AH22 cells, they synthesized about 1 X 10(3) and 5 X 10(3) reductase protein molecules per cell, respectively. A third plasmid, pARM1, containing a cytochrome P-450MC cDNA expression unit located between two reductase cDNA expression units synthesized 4 X 10(5) cytochrome P-450MC hemoprotein and 1 X 10(4) reductase protein molecules per cell. The cellular extracts of the AH22/pARM1 strain, which synthesized both rat enzymes, showed higher cytochrome c reductase and cytochrome P-450MC-dependent 7-ethoxycoumarin O-deethylation activities as compared to extracts of the AH22/pAMC1 strain, which synthesized only rat cytochrome P-450MC. 7-Ethoxycoumarin O-deethylation activity in the cellular extract of AH22/pARM1 strain was partly inhibited by the addition of anti-rat reductase IgG. In addition, whole AH22/pARM1 cells exhibited higher monooxygenase activity toward acetanilide and 7-ethoxycoumarin than control AH22/pAMC1 cells. These results indicated that a functional electron-transport chain consisting of rat NADPH-cytochrome P-450 reductase and rat cytochrome P-450MC was constructed in S. cerevisiae cells.

Amino Acid Sequence↗
PubMed1986

Molecular cloning and sequence analysis of full-length cDNA for rabbit liver NADPH-cytochrome P-450 reductase mRNA.

The nucleotide sequence of the mRNA for NADPH-cytochrome P-450 reductase from rabbit liver was determined from a full-length cDNA clone (pFP105). The clone contains 2,269 nucleotides complementary to rabbit liver reductase mRNA. The single open reading frame of 2,037 nucleotides codes for a 679-amino acid polypeptide with a calculated molecular weight of 76,583 daltons. The cloned cDNA contains the complete 3'-noncoding region of 193 nucleotides, including 68 nucleotides of poly(A), and 39 nucleotides of the 5'-noncoding region. The nucleotide sequence in the coding region of cDNA of rabbit reductase (pFP105) showed 85% homology to that of rat reductase (Porter, T.D. & Kasper, C.B. (1985) Proc. Natl. Acad. Sci. U.S. 82, 973-977, and Murakami, H. et al. (1986) DNA 5, 1-10). Rabbit reductase has one more amino acid residue than the rat enzyme, and the amino acid compositions of the two enzymes are similar. The amino acid sequence of the rabbit enzyme showed 91% identity with that of the rat enzyme. The segment related to binding of FMN and FAD was well conserved among rabbit, rat, and pig reductases. The sequence related to AMP moiety-binding was also conserved among these species, and was found in the amino acid sequence of NADH-cytochrome b5 reductase, another flavoenzyme in the microsomal electron transport system.

Amino Acid Sequence↗
PubMed1986

[Qualitative determination of infarct segment by Fourier analysis using gated cardiac pool emission computed tomography].

As a new method for regional wall motion analysis, the tomographic functional images, including "coronal", "sagittal" and "four-chamber" sections, were produced by applying the fundamental Fourier analysis using gated cardiac pool emission computed tomography (POOL-SPECT). Segmental wall motion was qualitatively assessed from the functional images in 10 normal subjects and in 48 patients with myocardial infarction. The results were compared with those assessed by gated blood pool planar images (modified LAO 45), two-dimensional echocardiography (2DE) or contrast left ventriculography (LVG). The following results were obtained. 1. POOL-SPECT imaging could separate the ventricle in three dimensions from the neighboring cardiovascular system by avoiding the overlapping blood pool to make accurate recognition of regional wall motion. 2. The functional tomograms had greater clinical efficacy in the diagnosis of infarcted segments than did the conventional equilibrium method, with high sensitivity (93/99, 93.9%), specificity (128/141, 90.8%) and accuracy (221/240, 92.1%), especially in the apical and inferoposterior portions. 3. Tomographic functional imaging facilitated estimating segmental cardiac performance from spatial and temporal aspects. The amplitude image which expresses regional stroke volume was readily available to detect hypokinesis and akinesis. The phase image of the initial cardiac movement was very useful for diagnosing dyskinesis. 4. In comparing the qualitative analysis with 2DE or LVG, complete agreement was observed in 80% (128/160) and 85.1% (149/175) of segments, though POOL-SPECT imaging showed underestimations in 11% of the segments. In conclusion, POOL-SPECT can be performed repeatedly without potential risks and the tomographic functional images derived from application of Fourier analysis to POOL-SPECT images are very useful for qualitative and three-dimensional analysis of regional wall motion. Thus, this technique may be a promising procedure in clinical investigations, obviating the disadvantages of conventional methods.

Adult↗
PubMed1985

Human-human hybridomas secreting antibodies specific to human lung carcinoma.

Human Namalwa cells were screened in serum-free medium and in 6-thioguanine, then fused with human lymphocytes from lymph nodes of lung adenocarcinoma cancer patients. Extensive testing using 14 lung cancer cell lines, 11 other cancer cell lines and 4 normal fibroblast lines identified monoclonal antibodies produced by 4 hybridoma clones that reacted specifically with lung adenocarcinoma cells. These monoclonal antibodies also reacted with lung adenocarcinoma tissues and not normal tissues or erythrocytes of any blood type. These hybridoma clones grew and stably secreted the antibodies in serum-free medium as well as in serum-containing medium.

Adenocarcinoma↗