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Biomedical subjects

K Yazaki

Publications and source records attributed to K Yazaki.

At least 19 recordsLinked to original sources
PubMed1994

High-level expression of porcine muscle adenylate kinase in Escherichia coli: effects of the copy number of the gene and the translational initiation signals.

Porcine muscle adenylate kinase (ADK) was overproduced in Escherichia coli using the expression plasmid with double A-T-G codon at the translational starting site and the Shine-Dalgarno (SD) sequence 10 bp apart from the first A-T-G. We used the expression vectors pKK223-3 and pMK2. pMK2 is about 10-20 times larger in copy number than pK223-3. For both vectors, duplication of A-T-G was effective and the quantity of the expressed ADK from the double A-T-G plasmid was 2 approximately 4-fold more than that achieved when only one A-T-G was present. The amount of the produced ADK was maximum in the case of using pMK2 with double A-T-G. The overproduced ADK formed inclusion bodies in E. coli. It was solubilized in 6 M guanidine hydrochloride and refolded. Through two steps of column chromatography, ADK was purified. It has the same amino acid composition and grossly the same activity as that reported by Schirmer et al. (1970). Its amino acid sequence of the NH2-terminal region was identical with that deduced from the cDNA sequence including the NH2-terminal methionine.

Adenylate Kinase↗
PubMed1994

Hairpin and dimer structures of linear plasmid-like DNAs in mitochondria of Paramecium caudatum.

The molecular structure of plasmid-like DNAs (designated type-II) which were isolated from mitochondria in the ciliated protozoan Paramecium caudatum was characterized. These type-II DNAs are always detected as a set of four kinds with sizes of 8.2, 4.1, 2.8 and 1.4 kb. The DNAs of 8.2 and 2.8 kb exist as dimers consisting of 4.1- and 1.4-kb monomer molecules, respectively. Electron microscopic observations indicated configurations of a hairpin structure that had a protruding end of single-stranded DNA in one terminus and a loop in the other terminus. The monomers stick together with base-pairing in opposite directions at the protruding end to form the dimers, suggesting the presence of inverted repeats. These unusual dimers may have a role in replication of the DNAs in which the monomers can serve as a primer for each other.

Animals↗
PubMed1994

Functional analysis of a light-responsive plant bZIP transcriptional regulator.

Common plant regulatory factor 1 (CPRF1) is a parsley basic region/leucine zipper (bZIP) transcription factor that recognizes specific nucleotide sequences containing ACGT cores. Such a sequence is contained within LRU1, the composite light regulatory unit that is necessary and sufficient for light-dependent activity of the parsley chalcone synthase (CHS) promoter. After light treatment of both etiolated and green seedlings, CPRF1 mRNA levels increased prior to CHS mRNA accumulation. The change in CPRF1 mRNA leads to a light-responsive increase in CPRF1 protein. Transient expression analysis in parsley protoplasts using the CPRF1 promoter fused to the beta-glucuronidase (GUS) open reading frame indicated that light-dependent CPRF1 mRNA accumulation was under transcriptional control. The 5' untranslated region of the CPRF1 gene includes a cis-acting nucleotide sequence that contains two ACGT elements at a distance of 12 bp between their palindromic centers. This feature is reminiscent of as-1 and octopine synthase (ocs) elements identified in promoters from plant pathogens. This double ACGT Element element, designated dACECPRF1, stimulated transcription when placed 5' to a heterologous core promoter. CPRF1 bound to dACECPRF1 DNA as well as to the ACGT element from the CHS promoter in vitro. Cotransfection experiments demonstrated that CPRF1 interacts with these elements in vivo and that overexpression of CPRF1 actually reduced light-dependent transcription from the CHS promoter. CPRF1 thus appears to contribute to the regulation of the CPRF1 gene and to interfere with the activities of light-regulated promoters.

Acyltransferases↗
PubMed1994

Expression of polydnavirus genes from the parasitoid wasp Cotesia kariyai in two noctuid hosts.

DNA purified from polydnavirus particles isolated from the parasitoid wasp Cotesia kariyai contained double-stranded closed circular molecules which were polydisperse in molecular weight. 2 days after viral injection into the host armyworm larvae viral DNA was detected in all tested larval tissues, including haemocytes, fat body, nerve cord and brain. Viral transcripts were also observed in all the tissues of virus-injected larvae. The most specific tissue was haemocytes because more viral DNA and RNA was detected than in the other tissues. Viral transcripts were not detected in haemocytes of virus-injected larvae of common cutworm. The present data suggest that C. kariyai virus (CkV) gene expression occurs species-specifically, although viral DNA can be detected in all tested tissues of the habitual host armyworm.

Animals↗
PubMed1994

Effects of glycated protein on the expression of very late antigen 5 (VLA5), a fibronectin receptor, of cultured rat mesangial cells.

Advanced glycosylation end products are believed to play a role in the increase in extracellular matrix in diabetic glomerulosclerosis via a pathway involving a mesangial cell fibronectin receptor. In the present study, I assessed cultured rat mesangial cells for the presence of mRNA for VLA5, one of the fibronectin receptors. Using these cells, I also evaluated the effects of glycated proteins on the expression of VLA5 and fibronectin. Mesangial cells of Wistar rats were cultured in RPMI 1640 containing 20% FCS. The cells were incubated for 72 hr in a medium containing 50 mg/ml of nonglycated BSA or in a medium containing 50 mg/ml glycated BSA (AGE-BSA). Immunostaining and Northern blot analyses showed that the cells incubated with AGE-BSA exhibited a decrease in VLA5 protein and related mRNA, but showed an increase in the synthesis of fibronectin and related mRNA. On the other hand, non-glycated BSA did not induce these changes in the expression of VLA5 or fibronectin in the mesanginal cells. Northern blot analysis for VLA5 mRNA was also conducted using mesangial cells cultured in a medium with a high glucose concentration (30 mM). However, the high glucose condition did not have any effect on the expression of VLA5 protein or related mRNA. These results suggest that glycated proteins may regulate fibronectin synthesis in mesangial cells by modifying the expression of fibronectin receptors, such as the inhibition of VLA5 synthesis that acts as negative feedback of fibronectin synthesis.

Animals↗
PubMed1992

Protective effect of vitamin E supplementation on increased thermal stability of collagen in diabetic rats.

Products similar to non-enzymatic glycation end products are known to arise from the interactions between proteins and lipid peroxides in vitro. In this study, we assessed the effect of vitamin E, which possibly modifies lipid peroxide, on advanced glycation end products or similar products in vivo by measuring the fluorescence and thermal rupture time of tail tendon collagen in streptozotocin-induced diabetic rats. The diabetic rats and non-diabetic rats were fed a vitamin E supplemented diet, and a control diet starting 3 days after the streptozotocin injection. After the 4-week treatment, the serum lipid peroxide levels expressed as thiobarbituric acid reactants in the diabetic rats on control diet (15.9 +/- 2.6 mumol/l[SEM]) were significantly (p less than 0.05) higher than in the non-diabetic rats (7.9 +/- 1.3 mumol/l on control diet and 3.3 +/- 0.4 mumol/l on supplemented diet), but the levels in the diabetic rats on supplemented diet (7.9 +/- 2.3 mumol/l) were reduced to the normal levels. No significant differences were found in serum glucose and glycated haemoglobin levels within the diabetic rats on control and supplemented diets. Both the fluorescence and thermal rupture time of collagen were significantly (p less than 0.05) increased in the diabetic rats on both diets compared with those in the corresponding non-diabetic rats. Although there was no significant difference in the collagen-linked fluorescence within the diabetic rats on control and supplemented diets, the thermal rupture time was significantly (p less than 0.01) shortened with supplemented diet (10.8 +/- 0.7 min on supplemented diet vs 15.0 +/- 0.7 min on control diet).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Possible participation of a prostaglandin E1 analogue in the aggravation of diabetic nephropathy.

A relation between the progression of diabetic nephropathy and glomerular hyperfiltration has been speculated. We describe two cases of non-insulin-dependent diabetic males aged 55 and 59 years in whom diabetic nephropathy was aggravated during the administration of limaprost, a a prostaglandin E1 analogue with a vasodilatory action. We also observed a short-term effect of limaprost on renal hemodynamics in three cases with diabetic nephropathy. In case 1, one year after limaprost administration the serum albumin level fell from 3.6 to 2.6 g/dl and the serum creatinine level rose from 1.0 to 1.6 mg/dl. In case 2, 9 months after limaprost administration the serum albumin level fell from 3.6 to 2.9 g/dl and the serum creatinine level rose from 1.8 to 2.3 mg/dl. In the latter stages of limaprost administration, the downslopes of reciprocal serum creatinine against time appeared to be augmented in the two cases. After the 3-day administration of limaprost, the peripheral and renal blood flows, and the glomerular filtration rate (GFR) were observed to rise, but the filtration fraction (FF) and urinary protein output were elevated. Keeping in mind the pre-existing renal damage, the increases in GFR and FF suggested acceleration of compensatory glomerular hyperfiltration in less damaged surviving glomeruli. The sustained acceleration of hyperfiltration with long-term administration of limaprost as an exogenous vasodilatory prostaglandin was assumed to eventuate in the aggravation of diabetic nephropathy. Attention should be paid to drugs which increase GFR in patients with established diabetic nephropathy.

Alprostadil↗
PubMed1992

Insulin-dependent diabetes mellitus showing microangiopathic hemolytic anemia and chronic disseminated intravascular coagulation.

It has been reported that microangiopathic hemolytic anemia occasionally occurs in patients with severe diabetic microangiopathy. We report a case of insulin-dependent diabetes mellitus in whom microangiopathic hemolytic anemia and chronic disseminated intravascular coagulation (DIC) were thought to be complicated. The patient showed fragmentation hemolytic anemia and progressive diabetic microangiopathy, together with a mild elevation of serum fibrin(ogen) degradation products. Considering the state of chronic DIC, heparin therapy was started, but mild hemolysis persisted. It is possible that microangiopathic hemolytic anemia and chronic DIC cause a vicious cycle in patients with severe diabetic microangiopathy, leading to rapid progression of diabetic microangiopathy.

Adult↗
PubMed1992

[Maintenance chemotherapy using UFT and FT for gynecological malignant tumors. The Gunma Prefectural Society for Study of Chemotherapy for Gynecological Cancer].

The Gunma Prefectural Society for Study of Chemotherapy for Gynecological Cancer made a comparative study on postoperative supplementary chemotherapy including UFT and FT-E for gynecological malignant tumors. The number of cases registered totaled 182, which was broken down into ovarian cancer 53 cases, uterine cervical cancer 89 cases and endometrial cancer 30 cases. Complete cases among them consisted of ovarian cancer 53 cases, uterine cervical cancer 86 cases and endometrial cancer 27 cases for a total of 166 cases. Ovarian cancer was stratified into the completely and incompletely removed cases, uterine cervical cancer into postoperative non-irradiated and irradiated cases and endometrial cancer into the positive metastasis (+) group and negative metastasis (-) group. Then the UFT administration group and FT-E administration group were compared for postoperative survival. There were control groups for both ovarian and endometrial cancer. UFT administration showed a significant improvement in the survival rate (P < 0.05) compared to the FT-E administration group in the cases of ovarian cancer completely removed and the cases of endometrial cancer irradiated after operation. No significant difference was observed between other groups compared. The incidence of side effects was 20.6% (20/97) in the UFT administration group and 3.6% (2/55) in the FT-E group. Neither group showed any serious side effects.

Adult↗
PubMed1991

Woodfordin D and oenothein A, trimeric hydrolyzable tannins of macro-ring structure with antitumor activity.

Two new antitumor trimeric hydrolyzable tannins, woodfordin D (5) and oenothein A (13), were isolated from the dried flowers of Woodfordia fruticosa, and their macrocyclic structures, which have a novel constituent unit (woodfordinoyl group) connecting the monomers, have been elucidated on the basis of spectral and chemical evidence. Oenothein A (13) was also isolated from the leaves of Oenothera biennis.

Antineoplastic Agents, Phytogenic↗
PubMed1991

Ataxic hemiparesis due to small semioval center infarction--consideration of the neuroanatomical disruptions responsible for ataxic hemiparesis.

A 63-year-old man with clinical features of typical ataxic hemiparesis is reported. CT scan and magnetic resonance imaging showed a small infarction in the contralateral semioval center near the parietal cortex. Of note is the previously unreported site of the lesion relative to this syndrome. The neuroanatomical basis for the ataxic hemiparesis syndrome is discussed.

Ataxia↗
PubMed1991

Neuroradiological findings of paretic neurosyphilis, a case report.

Neuroradiological findings of a patient with paretic neurosyphilis are described. A 50-year-old male patient showed personality changes, severe dementia and some neurological deficits. Serological analysis of serum and cerebrospinal fluid demonstrated the presence of antibodies to Treponema pallidum. Computed tomography showed diffuse cerebral cortical atrophy and ventricular dilatation, and magnetic resonance (MR) imaging revealed some small abnormal signals in the white matter. Single photon emission tomography using [123I] N-isopropyl-p-iodoamphetamine (IMP-SPECT) indicated decreased activities, most markedly in the right frontal and bitemporal cortices. Although the neuroradiological findings were nonspecific, the MR imaging and IMP-SPECT findings were interesting because they have not been described previously to our knowledge.

Antibodies, Bacterial↗