Search PubMed⌕ Search

Biomedical subjects

K Shirabe

Publications and source records attributed to K Shirabe.

At least 127 records · Page 7Linked to original sources
PubMed1989

Decrease of anion selectivity caused by mutation of Thr501 and Gly502 to Glu in the hydrophobic domain of the colicin E1 channel.

Structure-function relations of the colicin E1 ion channel were studied through the effects of mutations in the 35-residue hydrophobic region of the channel polypeptide and neighboring residues in the channel domain. Mutation of neutral residues threonine 501 and glycine 502 to a more polar or charged glutamic acid generated a protein whose channel conductance properties in each case had a decreased selectivity for anions. There was no significant effect on ion selectivity caused by mutations that changed residue charge outside the hydrophobic domain at the neighboring aspartic acid 509 or at glycine 439. The Thr501----Glu and Gly502----Glu mutants possessed lower cytotoxic and in vitro activity. An altered thermolysin cleavage pattern and a greater binding to membrane vesicles at pH greater than 4.5 of the Gly502----Glu mutant indicated greater exposure of its COOH-terminal hydrophobic domain in solution. It is concluded that the hydrophobic nature of threonine 501 and glycine 502 is important in the structure of the channel lumen and the soluble colicin. Altering proline 462, a residue conserved in five sequenced channel-forming colicins, had no significant effect on channel properties. These conclusions are discussed in the context of sequence-structure-function concepts for channel proteins.

Amino Acid Sequence↗
PubMed1989

Angiographically undetected small hepatocellular carcinoma: clinicopathological characteristics, follow-up and treatment.

We studied 36 cases (38 nodules) of small hepatocellular carcinoma with special attention directed to detectability using angiography and histology. Among the 38 nodules, 31 nodules (81.6%) were evident. The remaining seven (18.4%) were not evident angiographically but were detected using ultrasonography and/or computed tomography, prior to angiography. An elevated level of serum alpha-fetoprotein also suggested a diagnosis of hepatocellular carcinoma. When comparisons were made between angiographically detected and undetected nodules, there was no statistically significant difference in parameters, including sex of the patient, tumor size, location of the tumor, positive rate for hepatitis B surface antigen, history of liver disease and values of alpha-fetoprotein. The small hepatocellular carcinomas not detected angiographically and evidenced only histologically had the following characteristics: (i) no fibrous capsule surrounding the nodules; (ii) well-differentiated tumors; (iii) replacing growth pattern of cancer cells, and (iv) remains of portal tracts within the tumor. The replacing growth pattern and the presence of portal tracts may correlate with the low detectability in angiography. When a definite diagnosis of angiographically undetectable tumors cannot be made using close surveillance with ultrasonography or alpha-fetoprotein and/or needle biopsy under ultrasonic guide, surgical intervention should be considered, particularly for patients at high risk for hepatocellular carcinoma.

Aged↗
PubMed1989

Morphologic and functional changes in the remnant liver following resection for cirrhosis or chronic hepatitis.

We studied the late effects of hepatic resection on the remnant liver in patients with cirrhosis or chronic hepatitis. Data were obtained from 15 patients who underwent primary resection for hepatocellular carcinoma, followed by a second operation for recurrence. The mean interval between primary and second operations was 21.5 months (range, 7-39 months). When we compared the histologic features of the resected specimens obtained at the two operations, no apparent changes were noted in 14 of the 15 patients who had had an uneventful perioperative course. However, in the remaining patient, who had experienced postoperative intraperitoneal bleeding, the histologic diagnosis was changed from chronic inactive hepatitis to cirrhosis 7 months later. With regard to serum chemistry, there was no statistically significant difference in values between the two operations. We conclude that hepatic resection does not derange morphologic and functional status of the remnant liver and that advancement of chronic liver disease may occur in case of perioperative complications leading to liver cell damage.

Adult↗
PubMed1989

Long-term surviving patients with hepatocellular carcinoma comprised of dense collagenous stroma.

In two patients with hepatocellular carcinoma (HCC), treated surgically, we observed a dense collagenous stroma not heretofore reported. Grossly, the tumors consisted of a broad area of dense collagenous stroma that embedded the nodules of the HCC. Microscopically, nodules of the cancer cells were widely separated by this dense fibrous stroma, in association with surrounding inflammatory infiltrates, composed mainly of lymphocytes. These two patients had lived, respectively, for 10 yr and 2 months, and 8 yr and 9 months, despite precarious clinical states. HCC with characteristics such as a grossly distinct dense collagenous stroma and an inflammatory infiltrate may relate to a distinct category with a favorable prognosis.

Carcinoma, Hepatocellular↗
PubMed1989

[Eight cases of non-resectable hepatocellular carcinoma surviving for more than 3 years after Lipiodol administration].

From December 1982 to February 1986, selective regional cancer chemotherapy using Lipiodol plus anticancer drug (Lipiodolization) was prescribed for 87 patients with non-resectable hepatocellular carcinoma (HCC). Eight out of 87 cases survived for more than 3 years. The mean age of the 8 long survivors was 52.6. In the liver function, 2 cases were in Child A, 5 cases in Child B, and 1 case in Child C. The largest diameter of HCCs was 5.3 cm, and the number of the tumors was one in 6 cases, two in one case, and three in one case. No vascular invasion was detected on hepatic angiography. These findings suggested that long survivors in lipiodolization are not in far advanced HCCs. For these 8 cases, lipiodolization was repeatedly prescribed from two to 6 times. The largest amount of adriamycin was 192 mg/case. The longest survivor has lived for 5 years and 6 months after first lipiodolization. After lipiodolization, one tumor vanished, and three tumors decreased in size. Although seven tumors increased in size after lipiodolization, the tumor doubling time of seven tumors were 64, 265, 313, 317, 350, and 1943 days (average 539 +/- 639 days). It is possible that lipiodolization remarkably inhibited tumor growth. Nevertheless, in 5 out of 7 cases, the daughter lesions increased in size and number, although the main tumors grew slowly. Lipiodolization was less effective for newly arising daughter lesions than main lesions.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1985

Positive regulation of the colicin E1 gene by cyclic AMP and cyclic AMP receptor protein.

In previous experiments, we showed that the in vivo transcription of the colicin E1 gene was dependent on cyclic AMP in adenylate cyclase-defective mutant cells of Escherichia coli (Ebina, Y. and Nakazawa, A (1983) J. Biol. Chem. 258, 7072-7078). We now show that cyclic AMP and cyclic AMP receptor protein stimulated the in vitro transcription of the gene in the presence of spermidine. As determined in DNase I protection experiments, two binding sites for the complex of cyclic AMP and the receptor protein were identified about 60 base pairs (CRP-1) and 110 base pairs (CRP-2) upstream from the transcription initiation site of the colicin E1 gene. CRP-1 had a higher affinity for the complex than that of CRP-2. Substituting an unrelated DNA sequence for CRP-2 reduced the efficiency of in vitro stimulation of the gene by cyclic AMP and the receptor protein. These potential binding sites for the cyclic AMP-cyclic AMP receptor protein complex probably participate in the stimulation of the colicin E1 gene transcription.

Base Sequence↗
PubMed1984

Transcription analysis of the lexA gene of Escherichia coli: attenuation and cotranscription with the neighboring region.

The lexA gene of Escherichia coli encodes a repressor of the genes whose expression is induced by the agents that result in DNA damage. In vivo transcripts of the lexA gene consisted of two species; mRNA-1 of 673 bases and mRNA-2 of approximately 3,000 bases. The transcription in vivo started at a site which was two-base pairs downstream from the in vitro initiation site reported previously. The majority of the transcription stopped at a series of T residues preceeded by a dyad symmetry located immediately after the lexA gene. A small fraction of the transcription passed through the termination site to form the mRNA of downstream gene(s) which would be related to the "SOS functions".

Bacterial Proteins↗
PubMed1983

Plasmid-encoded regulation of colicin E1 gene expression.

A plasmid-encoded factor that regulates the expression of the colicin E1 gene was found in molecular cloning experiments. The 2,294-base-pair AvaII fragment of the colicin E1 plasmid (ColE1) carrying the colicin E1 structural gene and the promoter-operator region had the same information with respect to the repressibility and inducibility of colicin E1 synthesis as the original ColE1 plasmid. An operon fusion was constructed between the 204-bp fragment containing the colicin E1 promoter-operator and xylE, the structural gene for catechol 2,3-dioxygenase encoded on the TOL plasmid of Pseudomonas putida. The synthesis of the dioxygenase from the resulting plasmid occurred in recA+, but not in recA- cells and was derepressed in the recA lexA(Def) double mutant. These results indicate that the ColE1 plasmid has no repressor gene for colicin E1 synthesis and that the lexA protein functions as a repressor. Colicin E1 gene expression was adenosine 3',5'-phosphate (cAMP) dependent. Upon the removal of two PvuII fragments (2,000 bp in length) from the ColE1 plasmid, the induced synthesis of colicin E1 occurred in the adenylate-cyclase mutant even without cAMP. The 3,100-bp Tth111I fragment of the ColE1 plasmid cloned on pACYC177 restored the cAMP dependency of the deleted ColE1 plasmid. Since the deleted fragments correspond to the mobility region of ColE1, the cAMP dependency of the gene expression should be somehow related to the plasmid mobilization function.

Cloning, Molecular↗
PubMedDate not supplied

Immunoprotection of xenocytes in a hollow fiber bioartificial liver.

A new, hollow fiber bioartificial liver (BAL) was tested in an anhepatic rabbit model to assess the hollow fiber membrane as an immunologic barrier. The extracorporeal BAL contained rat hepatocytes (xenocytes) entrapped in collagen gel inside the lumen of hollow fibers with 100 kd nominal molecular weight cut-off. Blood from the anhepatic rabbit flowed in the extracapillary compartment. After 4 h of BAL hemoperfusion, the hepatocyte gels were tested for evidence of rabbit immunoglobulin and complement. Samples of the gels were stained with fluorescein isothiocyanate (FITC)-labeled antibodies directed against rabbit IgM, rabbit IgG (Fc and F[ab]2), and rabbit complement (C3) and studied by immunofluorescence microscopy. Enzyme-linked immunosorbent assay and Western blotting were used, respectively, to quantify and identify proteins inside the BAL and in the rabbit blood. These studies suggest that very little rabbit IgG (primarily fragments of IgG) and no IgM or C3 crossed the hollow fibers during hemoperfusion. Rat albumin steadily accumulated in the rabbit blood during hemoperfusion, which indicated membrane permeability to molecules of that size and stable hepatocyte function by the BAL. The authors conclude that hollow fibers with 100 kd nominal molecular weight cut-off provide immunoprotection for xenocytes in an extracorporeal BAL.

Animals↗
PubMedDate not supplied

A long-term survivor of ruptured hepatocellular carcinoma after hepatic resection.

We treated a patient who had previously undergone a hepatic resection for ruptured hepatocellular carcinoma (HCC) but developed a solitary peritoneal recurrence at the site of the incision 8 years and 9 months later. Since no other recurrence was evident, we resected the tumour. The primary tumour was 2.5 cm in size and histological examination revealed HCC without any histological risk factors for intrahepatic recurrence. The peritoneal tumour consisted of less differentiated cancer cells than those found in the primary tumour. The positive rates of Ki-67 were 10% in the primary tumour and 23.3% in the peritoneal recurrence. The DNA indexes in both tumours were considered to be identical. The comparison between the primary and peritoneal tumours suggested that the histological differentiation and proliferation activity can change after recurrence, in spite of consistent DNA ploidy contents. Clinically, a patient who undergoes a hepatic resection for ruptured HCC can survive for a long time, such as 10 years, if they have good liver function and small HCC without any histological risk factors for intrahepatic recurrence. However, since late recurrence is possible, a follow up for as long as 10 years is recommended.

Aneuploidy↗
PubMedDate not supplied

A comparative study on effects of doxorubicin alone or mixed with lipiodol given through the hepatic artery or portal vein for liver tumors in rats.

Vascular feeding of metastatic liver tumors at early stage is uncertain. It is controversial whether anticancer agents should be given through the hepatic artery or portal vein. In order to clarify this point, a rat model of liver metastases generated by an intraportal injection of syngeneic tumor cells was used to determine the optimal regional chemotherapeutic modality for early hepatic metastases. The rats given the tumor cells through the portal vein were placed into 5 groups: In groups I and II, Adriamycin (ADR) 4 mg/kg alone was given either into the hepatic artery or into the portal vein, respectively, 24 h after the inoculation of tumor cells. In groups III and IV, ADR mixed with lipiodol (lipiodolized ADR) 4 mg/kg was given into the hepatic artery or into the portal vein, respectively, 24 h after inoculation. For the group V rats, no treatment was given after inoculation of the tumor. When a comparison was made with regard to the forms of anticancer drug administered, statistically significant differences in survival rates were recognized between groups I and III (p < 0.001), and groups II and IV (p < 0.05). The anticancer agent not mixed with lipiodol and given through the hepatic artery had a more preventive effect than that given through the portal vein. Thus, we conclude that administration of ADR not mixed with lipiodol and given through the hepatic artery is the preferred modality for treating early metastatic liver tumors.

Animals↗
PubMedDate not supplied

Extracorporeal application of a gel-entrapment, bioartificial liver: demonstration of drug metabolism and other biochemical functions.

Metabolic activity of a gel-entrapment, hollow fiber, bioartificial liver was evaluated in vitro and during extracorporeal hemoperfusion in an anhepatic rabbit model. The bioartificial liver contained either 100 million rat hepatocytes (n = 12), fibroblasts (n = 3), or no cells (n = 7) during hemoperfusion of anhepatic rabbits. Eight other anhepatic rabbits were studied without hemoperfusion as anhepatic controls, and three sham rabbits served as normal controls. Albumin production rates (mean +/- SEM) were similar during in vitro (17.0 +/- 2.8 micrograms/h) and extracorporeal (18.0 +/- 4.0 micrograms/h) application of the hepatocyte bioartificial liver. Exogenous glucose requirements were reduced (p < 0.01) and euglycemia was prolonged (p < 0.001) in anhepatic rabbits treated with the hepatocyte bioartificial liver. The maximum rate of glucose production by the hepatocyte bioartificial liver ranged from 50-80 micrograms/h. Plasma concentrations of aromatic amino acids, proline, alanine, and ammonia were normalized in anhepatic rabbits during hepatocyte hemoperfusion. Gel-entrapped hepatocytes in the bioartifical liver performed sulfation and glucuronidation of 4-methylumbelliferone. P450 activity was demonstrated during both in vitro and extracorporeal application of the BAL device by the formation of 3-hydroxy-lidocaine, the major metabolite of lidocaine biotransformation by gel-entrapped rat hepatocytes. In summary, a gel-entrapment, bioartificial liver performed multiple hepatocyte-specific functions without adverse side effects during extracorporeal application in an anhepatic, small animal model. With its potential for short term support of acute liver failure, scale-up of the current bioartificial liver device is indicated for further investigations in large animal, preclinical trials.

Albumins↗