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Biomedical subjects

A Yasui

Publications and source records attributed to A Yasui.

At least 109 records · Page 6Linked to original sources
PubMed1991

[Radionuclide cavography before and after percutaneous transluminal angioplasty in Budd-Chiari web: case report].

A case of the Budd-Chiari syndrome due to a web of the hepatic inferior vena cava (IVC) is reported. A 54-year-old male with mild liver dysfunction was suspected with IVC obstruction from the screening CT which revealed liver cirrhosis with marked caudate lobe enlargement and dilatation of azygous and hemiazygous vein. Subsequent radionuclide cavography with 99mTc-HSA clearly demonstrated IVC obstruction, but failed to clarify the site or type of the obstruction. Finally contrast cavography diagnosed a web of the hepatic IVC, which was treated by percutaneous transluminal angioplasty (PTA). During two-year follow-up after PTA none of the radionuclide cavographies showed reocclusion of the IVC and as a result contrast cavography was avoided. Radionuclide cavography, therefore, was a useful method for evaluating IVC obstruction before and after PTA for the Budd-Chiari web.

Angioplasty, Balloon, Coronary↗
PubMed1991

[Cholangiographic studies on bile duct branches of the caudate lobe in resected cases with biliary tract carcinoma involving the hepatic hilus].

Diagnostic value of the cholangiography was studied for carcinoma of the biliary tract involving the hepatic hilus, and special attention was paid on the cholangiogram of the bile duct branches (B1) of the caudate lobe. Cholangiograms of B1 were compared with pathologic findings in 42 (27 bile duct carcinomas, 15 gallbladder carcinomas) of 43 cases of biliary tract carcinomas. Sixty-four of B1 in the 42 cases could be studied radiologically and histopathologically. The findings of the root of B1 were classified into 4 groups: group A, not stenotic; group B, short segmental stenosis; group C, long segmental stenosis and group D, poorly imaged. Carcinoma invasion was found in 6 of 18 of group B, and in 9 of 16 of group C. Carcinoma was confirmed near the root of B1 in the remaining 7 of the 16 group C. Carcinoma invasion was found in 20 of 21 of group D, and invasion was suspected in the remaining one. Carcinomas were found in the root of B1 in all cases of poorly imaged or long segmental stenosis of B1, and in 33% of short segmental stenosis of B1. Therefore caudate lobe resection should be performed for carcinoma of the biliary tract involving the hepatic hilus.

Adult↗
PubMed1990

Matrix metalloproteinase 2 from human rheumatoid synovial fibroblasts. Purification and activation of the precursor and enzymic properties.

Human rheumatoid synovial cells in culture secrete at least three related metalloproteinases that digest extracellular matrix macromolecules. One of them, termed matrix metalloproteinase 2 (MMP-2), has been purified as an inactive zymogen (proMMP-2). The final product is homogeneous on SDS/PAGE with Mr = 72,000 under reducing conditions. The NH2-terminal sequence of proMMP-2 is Ala-Pro-Ser-Pro-Ile-Ile-Lys-Phe-Pro-Gly-Asp-Val-Ala-Pro-Lys-Thr, which is identical to that of the so-called '72-kDa type IV collagenase/gelatinase'. The zymogen can be rapidly activated by 4-aminophenylmercuric acetate to an active form of MMP-2 with Mr = 67,000, and the new NH2-terminal generated is Tyr-Asn-Phe-Phe-Pro-Arg-Lys-Pro-Lys-Trp-Asp-Lys-Asn-Gln-Ile. However, following 4-aminophenylmercuric acetate activation, MMP-2 is gradually inactivated by autolysis. Nine endopeptidases (trypsin, chymotrypsin, plasmin, plasma kallikrein, thrombin, neutrophil elastase, cathepsin G, matrix metalloproteinase 3, and thermolysin) were tested for their abilities to activate proMMP-2, but none had this ability. This contrasts with the proteolytic activation of proMMP-1 (procollagenase) and proMMP-3 (prostromelysin). The optimal activity of MMP-2 against azocoll is around pH 8.5, but about 50% of activity is retained at pH 6.5. Enzymic activity is inhibited by EDTA, 1,10-phenanthroline or tissue inhibitor of metalloproteinases, but not by inhibitors of serine, cysteine or aspartic proteinases. MMP-2 digests gelatin, fibronectin, laminin, and collagen type V, and to a lesser extent type IV collagen, cartilage proteoglycan and elastin. Comparative studies on digestion of collagen types IV and V by MMP-2 and MMP-3 (stromelysin) indicate that MMP-3 degrades type IV collagen more readily than MMP-2, while MMP-2 digests type V collagen effectively. Biosynthetic studies of MMPs using cultured human rheumatoid synovial fibroblasts indicated that the production of both proMMP-1 and proMMP-3 is negligible but it is greatly enhanced by the treatment with rabbit-macrophage-conditioned medium, whereas the synthesis of proMMP-2 is constitutively expressed by these cells and is not significantly affected by the treatment. This suggests that the physiological and/or pathological role of MMP-2 and its site of action may be different from those of MMP-1 and MMP-3.

Amino Acid Sequence↗
PubMed1990

Characterization of a superoxide dismutase gene from the archaebacterium Methanobacterium thermoautotrophicum.

A gene encoding superoxide dismutase (SOD) was cloned from the archaebacterium Methanobacterium thermoautotrophicum, the first example from an anaerobic bacterium. The deduced amino acid sequence showed overall similarity to sequences of known Mn- and Fe-SODs from aerobic organisms. Judging from a detailed sequence comparison, the cloned SOD gene is classified as Mn-SOD. By comparison of Mn-SOD sequences among various species it was suggested that archaebacterial superoxide dismutase is a direct descendant of a primordial enzyme. Between a putative promoter and the start codon there is an inverted repeat sequence which is also found in the counterpart of Halobacterium halobium.

Amino Acid Sequence↗
PubMed1990

Analysis of a human DNA excision repair gene involved in group A xeroderma pigmentosum and containing a zinc-finger domain.

Xeroderma pigmentosum (XP) is an autosomal recessive disease, characterized by a high incidence of sunlight-induced skin cancer. Cells from people with this condition are hypersensitive to ultraviolet because of a defect in DNA repair. There are nine genetic complementation groups of XP, groups A-H and a variant. We have cloned the mouse DNA repair gene that complements the defect of group A, the XPAC gene. Here we report molecular cloning of human and mouse XPAC complementary DNAs. Expression of XPAC cDNA confers ultraviolet-resistance on several group A cell lines, but not on lines of other XP groups. Almost all group A lines tested showed abnormality or absence of XPAC messenger RNAs. These results indicate that a defective XPAC gene causes group A XP. The human and mouse XPAC genes are located on chromosome 9q34.1 and chromosome 4C2, respectively. Human XPAC cDNA encodes a protein of 273 amino acids with a zinc-finger motif.

Amino Acid Sequence↗
PubMed1990

[Preoperative chemotherapy and anti-cancer effect of gastric carcinoma].

For the purpose of the study of macroscopical and histopathological anti-cancer effects, preoperative cancer chemotherapy was performed in 31 cases with gastric carcinoma. Gastric carcinoma with preoperative chemotherapy showed advanced cancer in 15 cases, and early cancer in 16 cases. During preoperative chemotherapy, the drug 5-Fu or 5'-DFUR was administered orally. The results were as follows; i) Macroscopical change of early cancer cases with anti-cancer chemotherapy showed the onset and healing of ulceration in the cancerous lesion and the change of granular pattern in the IIc floor. ii) Early cancer cases had a multi-centric histopathological anti-cancer effect which showed regenerative epithelium in the cancerous lesion. iii) The extent of the histopathological anti-cancer effect in advanced carcinoma showed greater in the deep layer of cancer invasion. Consequently, morphological changes of early cancer cases with chemotherapy are similar to the cases without chemotherapy. The onset of cancer damage in advanced carcinoma is in the cancer invasive zone, deep layer.

Administration, Oral↗
PubMed1990

DNA photoreactivating enzyme from the cyanobacterium Anacystis nidulans.

Photoreactivating enzyme, which specifically monomerizes pyrimidine dimers in UV-irradiated DNA, was purified 21,000-fold from the cyanobacterium Anacystis nidulans to apparent homogeneity with 41% overall yield. The enzyme consists of a single protein chain with 53,000 molecular weight. Maximal activity was found at pH 6.2 and 0.1 M NaCl. Purified photoreactivating enzyme exhibits a marked absorption spectrum with a main band in the blue region (maximum 437 nm), a protein band (maximum 266 nm), and a low intensity band above 500 nm. The molar extinction coefficient of native enzyme was estimated 53,000 at 437 nm. The action spectrum for photoreactivation shows maximal activity at 440 nm and correlates closely with the 437-nm absorption band. The enzyme contains two different intrinsic chromophores in equimolar amounts, which were identified as 7,8-didemethyl-8-hydroxy-5-deazariboflavin (FO) and (reduced) FAD. The low intensity absorption band of native photoreactivating enzyme exhibits a shoulder at 498 and maxima at 588 and 634 nm. This band is attributed to a neutral FAD semiquinone radical which accounts for the major part of the FAD present in dark equilibrated enzyme. Preillumination at 585 nm bleaches the semiquinone spectrum due to formation of fully reduced FAD, but exposure to air in the dark restores the spectrum completely. On preillumination at 437 nm the disappearance of FAD semiquinone is more rapid, indicating that the photoreduction is sensitized by the 8-hydroxy-5-deazaflavin chromophore. The 8-hydroxy-5-deazaflavin and possibly also the reduced FAD chromophore appear to act as a primary photon acceptor in the photoreactivation process.

Amino Acid Sequence↗
PubMed1990

Increased UV sensitivity of Escherichia coli cells after introduction of foreign photolyase genes.

High-expression plasmids for photolyase (phr) genes from the bacteria Escherichia coli, Anacystis nidulans, Streptomyces griseus and Halobacterium halobium and the yeast Saccharomyces cerevisiae were constructed and introduced into E. coli phr recA cells. As previously reported, al introduced phr genes provided the host cells with photoreactivation-repair activity and the introduced E. coli phr gene rendered the host cells more UV-resistant in the dark. E. coli cells harboring foreign phr genes, however, were found to be more sensitive to UV light in the dark than cells containing the vector plasmid only. These differences in UV sensitivity in the dark disappeared when the host cells had an additional mutation, uvrA, suggesting that the foreign photolyases inhibited the E. coli excision-repair system.

Base Sequence↗
PubMed1990

Novel C-terminal gastrin antagonists. Synthesis and biological activity.

The C-terminal tetrapeptide, Trp-Met-Asp-Phe-NH2, is a full agonist of gastrin, but des-Phe analogues, including Boc-Trp-Met-Asp-NH2, are antagonists. To ascertain the minimum structural requirement for an antagonist, we used conventional solution phase methodology to synthesize analogues with further modifications including removal of the alpha-amino group of Trp, conversion of the indole to a phenyl ring, and methylation of amide bonds. These analogues were tested for their effect on pentagastrin-stimulated acid release in dogs surgically prepared with a gastric fistula. When infused intravenously at a dose of 20 pmol kg-1 h-1, the peptides significantly inhibited acid secretion. The extent of inhibition ranged from 12% to 60%. Thus, tripeptide analogues based on the C-terminal sequence of gastrin act as potent and specific antagonists of gastrin-stimulated acid secretion.

Amino Acid Sequence↗
PubMed1990

Functional expression of 8-hydroxy-5-deazaflavin-dependent DNA photolyase from Anacystis nidulans in Streptomyces coelicolor.

The gene encoding Anacystis nidulans 5-deazaflavin-dependent photolyase (phr) was inserted into the Streptomyces vector pIJ385 to form a transcriptional fusion with the neomycin resistance (aph) gene. The resulting plasmid, pANPL, was introduced into Streptomyces coelicolor, a host which exhibits no detectable photolyase activity and provides 5-deazaflavins. Transformants expressed functional photolyase and could be cultured at much higher cell densities than A. nidulans. A two-step affinity protocol was used to purify photolyase to homogeneity. High-pressure liquid chromatographic analysis established the presence of 5-deazaflavin cofactors in the enzyme, showing that this expression system allows heterologous production of 5-deazaflavin-class photolyases.

Amino Acid Sequence↗
PubMed1990

Two cases of parathyroid carcinoma in patients on long-term hemodialysis.

Two cases of parathyroid carcinoma, in a 46-year-old male on maintenance hemodialysis for 135 months and a 55-year-old female on maintenance hemodialysis for 64 months were reported. In both cases, the parathyroid carcinoma showed local invasion and the other glands were hyperplasia and/or adenoma, which would support the concept of malignant transformation occurring in parathyroid hyperplasia. The concurrence of parathyroid carcinoma with hyperplasia and/or adenoma is a pertinent feature in patients on maintenance dialysis, although it is rare in primary parathyroid carcinoma.

Female↗
PubMed1990

[A progressive gastric cancer in which preoperative oral chemotherapy resulted in a histopathological "Grade 2" rating].

This paper describes a case of a Borrmann type 3 gastric cancer, in which the preoperative intermittent oral administration of 5'-DFUR over a short term resulted in a histopathological rating of Grade 2. A 56-year-old man preoperatively received an intermittent, oral administration of 5'-DFUR, 2, 100 mg/day. An upper gastrointestinal series and endoscopy revealed macroscopically an extremely slight remission. Histopathologically, however, a widespread, remarkable degeneration of cancer cells and fibrinogenesis of the framework were observed, these results leading to a change of rating to Grade 2.

Adenocarcinoma↗
PubMed1990

[Prognosis of gastric carcinoma sited in the cardiac part determined by the type of esophageal invasion].

A study has been made of type and prognosis of esophageal invasions exhibited by gastric carcinomas sited in the cardiac part of the stomach. Examined were 14 such cases of an adenocarcinoma with an esophageal invasion. Histopathologically, the invasions into the esophagus were classified into 4 types of severity, from 1 to 4, according to the depth of the invasion into the esophago-gastric junction (EGJ) and the pattern of the invasion to the oral side (thoracic side). The prognosis was found to be good for EGJ invasion that had penetrated to the pm and/or sm layer only, whereas it was very bad if the invasion had penetrated the entire EGJ wall (the pm, sm, mp, and the sa) and the infiltrative pattern had reached the oral side (thoracic side). Almost all patients given a type 4 classification soon had a recurrence after surgery and did not live beyond two years. Thus, a close relationship has been noted between the type of invasion into the esophagus and the prognosis.

Adenocarcinoma↗
PubMed1989

Expression of rat protein phosphatase 2C (IA) in Escherichia coli.

A cDNA containing the entire coding sequence of rat type 2C (IA) protein phosphatase was expressed in Escherichia coli. An extract of bacterial cells harboring the recombinant plasmid contained a major (Mr = 41,000 - 43,000) and a minor (Mr = 30,000) protein band; both of these reacted with an anti-type 2C protein phosphatase serum. The size of the major protein band agrees well with that of the 2C phosphatase conceptualized from the cognate cDNA. A Mg2+-dependent protein phosphatase activity was detected in extracts containing the recombinant protein, but not in host cell extracts. Based on these results, it is concluded that the isolated cDNA clone encodes a functional type 2C protein phosphatase.

Animals↗
PubMed1989

Molecular characterization of a gene encoding a photolyase from Streptomyces griseus.

By using a synthetic DNA probe derived from an amino acid sequence in the most conserved region of three known photolyases (Escherichia coli, Anacystis nidulans and Saccharomyces cerevisiae), we isolated a DNA fragment containing two long open reading frames (ORFs) from a genomic DNA library of Streptomyces griseus. One ORF encodes a polypeptide of 455 amino acids (Mr 50594), which exhibits substantial similarities with the other three photolyases. Photoreactivation-repair deficient E. coli cells could be converted into photoreactivatable ones by introduction of plasmids harboring this ORF, indicating that this is the photolyase gene of S. griseus. The deduced aa sequence of Streptomyces photolyase was most similar to that of E. coli. The putative DNA binding site as well as cofactor binding regions were proposed.

Amino Acid Sequence↗