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Biomedical subjects

Y Shima

Publications and source records attributed to Y Shima.

At least 19 recordsLinked to original sources
PubMed1999

Evolutionary molecular engineering by random elongation mutagenesis.

We describe a new method of random mutagenesis that employs the addition of peptide tails with random sequences to the C-terminal of enzyme molecules. A mutant population of catalase I from Bacillus stearothermophilus prepared by this method has a diversity in thermostability and enzyme activity equal to that obtained after random point mutagenesis. When a triple mutant of catalase I (I108T/D130N/1222T)-the thermostability of which is much lower than that of the wild type-was subjected to random elongation mutagenesis, we generated a mutant population containing only mutants with higher thermostability than the triple mutant. Some had an even higher stability than the wild-type enzyme, whose thermostability is considered to be optimized. These results indicate that peptide addition expands the protein sequence space resulting in a new fitness landscape. The enzyme can then move along the routes of the new landscape until it reaches a new optimum. The combination of random elongation mutagenesis with random point mutagenesis should be a useful approach to the in vitro evolution of proteins with new properties.

Amino Acid Sequence↗
PubMed1998

Properties of artificial proteins with random sequences.

A library of artificial proteins of 141 amino acid residues, of which 95 are random and which include 20 kinds of amino acids, was prepared. As the properties of the artificial random proteins are free from the evolutionary constraint, they can be used as a standard to discriminate the specialized properties of natural proteins. Out of the 25 identified random proteins, 5 are soluble in the cell lysate, indicating that about 20% of the random proteins expressed in Escherichia coli are expected to be soluble. Therefore, as natural soluble or insoluble proteins can arise from the line of soluble or insoluble ancestry, respectively, solubility does not seem a specialized property of natural proteins. The soluble random proteins RP3-42 and RP3-45 were purified and their properties were investigated.

Amino Acid Sequence↗
PubMed1998

Effects of an inhibitor of topoisomerase II, ICRF-193 on the formation of ultraviolet-induced chromosomal aberrations.

Treatments of Chinese hamster V79 cells during one cell cycle with a new type of topoisomerase II inhibitor, ICRF-193, which does not accumulate cleavable topoisomerase-DNA complexes induced both chromosome- and chromatid-type aberrations with high frequencies. Furthermore, ICRF-193 synergistically enhanced the yield of UVB-induced chromatid-type aberrations, chromatid exchanges in particular. Treated with ICRF-193 for the last 3 h before harvest, cells showed frequent incidence of chromatid-type aberrations and synergistic enhancement of UVB-induced chromatid-type aberrations, chromatid exchanges in particular. These results suggest that spontaneous and UVB-induced lesions might be ultimately transformed into chromatid-type aberrations by topoisomerase II-dependent checkpoint process(es) in the G2 phase of the cell cycle.

Animals↗
PubMed1998

A missense mutation of the gene for Na+,K(+)-ATPase alpha-subunit causes abnormal feeding behavior in Caenorhabditis elegans.

The Na+,K(+)-ATPase activity of membranes from a behavioral mutant of C. elegans was found to be about one-third that of the wild-type. The levels of mRNA and polypeptide of Na+,K(+)-ATPase alpha-subunit in the mutant were as high as those in the wild-type, but the level of the phosphorylated intermediate of the Na+,K(+)-ATPase in the mutant worm was 80% lower than that in the wild-type. A single predicted amino acid replacement (Leu to Phe) was found in a highly conserved region in the alpha-subunit that is involved in the formation of phosphorylated intermediate. The abnormal feeding behavior of the mutant worm may be attributed to this missense mutation.

Amino Acid Sequence↗
PubMed1998

Association of the Trp64Arg mutation of the beta3-adrenergic receptor with fatty liver and mild glucose intolerance in Japanese subjects.

The prevalence of a mutation of the codon for tryptophan 64 to arginine (Trp64Arg) in the beta3-adrenergic receptor gene was investigated by genotyping 261 Japanese subjects. The allelic frequency of this mutation was 0.18. Subjects with the homozygous W64R mutant alleles had a significantly higher prevalence of fatty liver, BMI, serum gamma-glutamyl transpeptidase, and serum leucine amino transpeptidase levels than those without the mutation. Individuals with this mutation also showed a higher fasting blood glucose level than those without this mutation. However, the prevalence of diabetes mellitus was no different between the three groups. These results suggest a potential association of the Trp64Arg mutation with higher morbidity of fatty liver and mild glucose intolerance.

Alleles↗
PubMed1998

Characterization of soluble artificial proteins with random sequences.

The structural and catalytic properties of two soluble random proteins, RP3-42 and RP3-45, of 141 amino acid residues were investigated. Although no marked secondary structure was detected by CD spectrum, sedimentation equilibrium and small-angle X-ray scattering studies showed that they form an oligomeric structure and are as compact as the molten globule. The random proteins have low but distinct esterase activity; the values of the second-order rate constant for the hydrolysis of p-nitrophenol were 0.78 and 1.39 M(-1) s(-1) for RP3-42 and RP3-45, respectively. The differences in the properties of the random and the native proteins are discussed from the evolutionary point of view.

Amino Acid Sequence↗
PubMed1998

Resection of pheochromocytoma under inferior vena caval isolation and extracorporeal charcoal hemoperfusion.

Resection of pheochromocytoma is associated with potential risks of hypertensive crises and serious arrhythmias due to massive release of catecholamines from the tumor. We report our surgical experience with complete inferior vena caval isolation and extracorporeal charcoal hemoperfusion (IVCI-CHP), which were performed to prevent systemic exposure to catecholamines during surgical manipulation. The IVCI-CHP significantly reduced the postfilter and systemic catecholamine levels compared with the prefilter levels (P<.01), indicating substantial catecholamine extraction (>90%) by the CHP filter. Reflecting the reduction of systemic exposure to catecholamines during IVCI-CHP, the patient's blood pressures were markedly stable. Our findings suggest that IVCI-CHP may be useful to minimize the risk of hypertensive crises during surgical manipulation of pheochromocytoma, by preventing systemic exposure to high levels of circulatory catecholamines.

Adrenal Gland Neoplasms↗
PubMed1998

Unusual variant of left paraduodenal hernia herniated into the mesocolic fossa leading to jejunal strangulation.

Paraduodenal hernia is a rare condition in which the small bowel loops are herniated into an unusual fossa in the periduodenal area. We treated a patient with paraduodenal hernia diagnosed preoperatively. A 28-year-old woman was admitted to our hospital because of intermittent abdominal pain. Abdominal ultrasonography revealed a large tumor adjacent to the pancreas. Provisional diagnosis made according to computed tomography (CT) findings was tumor of the pancreas tail. However, on a CT scan performed after the administration of diatrizoate meglumine/diatrizoate sodium (Gastrografin, Schering, Berlin, Germany) the mass was shown as a jejunum loop located between the stomach and the pancreas body. Subsequent laparotomy revealed that the jejunum loop was herniated into an unusually large mesocolic fossa and that the hernial orifice was covered by the adhesion between the transverse and descending colons. It seemed that the small intestine within the mesocolic fossa was strangulated by this adhesion. The patient's abdominal pain resolved postoperatively. These observations suggest that paraduodenal hernia should be suspected in patients with chronic, atypical abdominal pain, regardless of the findings for small bowel obstruction.

Adult↗
PubMed1998

Nitric oxide mediates cerulein-induced relaxation of canine sphincter of Oddi.

This study evaluates the hypothesis that cerulein relaxes the sphincter of Oddi (SO) via nitric oxide (NO). The spontaneous motility and the response to cerulein on the canine SO were recorded using a constant-perfusion technique. N(G)-L-arginine-methyl-ester (L-NAME) increased the spontaneous motility and dose-dependently reduced the cerulein-induced inhibitory response of the SO. After treatment with L-NAME at higher doses, cerulein induced an excitatory response. This effect was reversed by treatment with excess L-arginine. Similar results were obtained using cholecystokinin octapeptide in place of cerulein. In separate studies, cerulein generated increases in intracellular cAMP and cGMP levels in the SO. This indicates that the intracellular mechanism mediating cerulein-induced relaxation involves the production of cAMP and cGMP. On the other hand, treatment with L-NAME absorbed the increase in cAMP and cGMP levels by cerulein. These studies demonstrate that cerulein relaxes the canine SO mainly via NO, increasing intracellular cAMP and cGMP levels.

Animals↗
PubMed1998

Effects of zaprinast on renal nerve stimulation-induced anti-natriuresis in anaesthetized dogs.

1. We examined whether zaprinast, a putative cGMP-specific phosphodiesterase inhibitor, affects neural control of renal function in pentobarbital-anaesthetized dogs. 2. Renal nerve stimulation (1 Hz, 1 ms duration) reduced urine flow rate, urinary Na+ excretion (UNaV) and fractional excretion of Na+ (FENa) with little change in either renal blood flow (RBF) or glomerular filtration rate (GFR). 3. Intrarenal arterial infusion of zaprinast (10 and 100 micrograms/kg per min) increased basal urine flow rate, UNaV and FENa but not RBF or GFR. Zaprinast infusion (100 micrograms/kg per min) also increased renal venous plasma cGMP concentration and urinary cGMP excretion. 4. Renal nerve stimulation-induced reductions in UNaV and FENa were attenuated during zaprinast infusion, whereas the reduction in urine flow rate was resistant to zaprinast. 5. Renal nerve stimulation increased the renal venous plasma noradrenaline concentration and renal noradrenaline efflux, which remained unaffected during infusion of zaprinast (100 micrograms/kg per min). 6. The results of the present study suggest that zaprinast induces natriuresis and counteracts adrenergically induced antinatriuresis by acting on renal tubular sites in the dog kidney in vivo.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1998

[Successful treatment of pseudomyxoma peritonei using combination chemotherapy of intraperitoneal low-dose CDDP and oral 5'-DFUR administration].

We report a case of pseudomyxoma peritonei treated with combination chemotherapy. A 73-year-old woman was diagnosed as having psuedomyxoma peritonei originated from the vermiform appendix. Appendectomy was performed, and 10 mg of MMC was administered intraperitoneally. From day 7, 600 mg/day of 5'-DFUR was orally given for 2 years, and 20 mg of CDDP once a month was intraperitoneally administered seven times. The patient has been doing well with no evidence of tumor recurrence for two years after operation. Combination chemotherapy with CDDP and 5'-DFUR, as a biochemical modulation therapy, has fewer side effects and leads to better quality of life of patients. We recommend a combination chemotherapy with low-dose CDDP and 5'-DFUR for patients in poor general condition.

Administration, Oral↗
PubMed1997

Extensive RNA editing and possible double-stranded structures determining editing sites in the atpB transcripts of hornwort chloroplasts.

Three nonsense codons and an unusual initiation codon were located within the putative coding region of the atpB gene of chloroplast DNA of the hornwort Anthoceros formosae. Nucleotide sequencing of cDNA prepared from transcripts revealed extensive RNA editing. The unusual initiation codon ACG was changed to AUG and three nonsense codons were converted into sense codons. In total 15 C residues of the genomic DNA were replaced by U residues in the mRNA sequences, while 14 U residues were replaced by C residues. This is the highest number of editing events for a chloroplast mRNA reported so far. Partial editing was also shown in a cDNA clone where 23 sites were edited but six sites remained unedited, representing the existence of premature mRNA. The expected two-dimensional structure of the mRNA shows the existence of a sequence complementary to every editing site, which can produce continuous base pairing longer than 5 bp, suggesting that mispairing in the double strand is the site determinant for RNA editing in Anthoceros chloroplasts. Comparison of the cDNA sequence with other chloroplast genes suggests that the mechanism arose in the first land plants and has been reduced during evolution.

Amino Acid Sequence↗
PubMed1997

Myeloma biology and therapy. Present status and future developments.

Recent progress in cytokine studies has made it possible to understand the pathophysiological roles of cytokines in multiple myeloma. Specifically, interleukin (IL)-6 is a potent growth factor for myeloma cells and is also responsible for the progressive bone resorption characteristic of this disease. On the basis of this evidence, clinical trials to interfere with IL-6 signals have been initiated for the treatment of patients with advanced myeloma. Such a new therapeutic approach as well as myeloblative therapy should be able to provide us with the breakthrough needed to prevail over this so far incurable disease.

Antigens, CD↗
PubMed1997

[Clinical application of interleukin-6 receptor antibody].

Interleukin-6 (IL-6) is a pleiotropic cytokine which shows multiple biological functions. Pathological significance of IL-6 has been elucidated in various diseases including multiple myeloma, Castleman's disease, and rheumatoid arthritis. Thus the blockade of IL-6 signal transduction may be therapeutically effective for these diseases. For this purpose, humanized anti-IL-6 receptor antibody was prepared, and its therapeutic efficacy has been examined. Immediately after administration of humanized anti-IL-y receptor antibody to the patients with multiple myeloma, fever and systemic edema disappeared followed by the stability of M-protein which had been rapidly increased before the treatment. Humaniged anti-IL-6 receptor antibody also improved not only the chronic inflammatory symptoms but also laboratory findings such a hemoglobin, C-reactive protein, erythrocyte sedimentation rate observed both in Castleman's disease and in rheumatoid arthritis. The data suggest that the blockade of IL-6 signal transduction can be a new therapeutic approach based on the pathological significance of IL-6 in these diseases.

Antibodies↗