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Biomedical subjects

A Hara

Publications and source records attributed to A Hara.

At least 235 records · Page 13Linked to original sources
PubMed1997

[Central nervous system metastasis from non-functioning adrenocortical carcinoma: report of a case].

We report a rare case of brain tumor metastasizing from an adrenocortical carcinoma. A 47-year-old man was referred to our department on September 21, 1995, with complaints of episodic loss of consciousness and severe left motor weakness. There was a past history of left adrenalectomy performed in the Department of Surgery of our hospital 9 months before. On admission, computed tomography (CT) and magnetic resonance imaging (MRI) revealed two well circumscribed masses in the right frontal lobe with peritumoral, marked brain edema and metastasis to the lung. The brain tumor was successfully removed via frontal craniotomy 4 days after admission. Histological examination of the tumor specimen revealed metastatic anaplastic cell carcinoma, indicating metastasis from an adrenocortical carcinoma. After chemotherapy with cisplatin, pepleomycin and pirarubicin, he was discharged without neurological deficit. Two months postoperatively, however, the patient received 50 Gy of telecobalt radiation therapy to the whole brain because of recurrence. Three months after-wards, the patient returned complaining of general fatigue. Chest CT scan revealed further enlargement of the lung lesions. Despite repeated chemotherapy, the patient died of lung metastases eight weeks later. Central nervous system metastasis from adrenocortical carcinoma is exceedingly rare. To the best of our knowledge, only 5 cases have been reported. We report here another case of brain metastasis from adrenocortical carcinoma possibly via lung metastasis, and review the pertinent medical literature.

Adrenal Cortex Neoplasms↗
PubMed1997

No involvement of APC gene mutations in ulcerative colitis-associated rat colon carcinogenesis induced by 1-hydroxyanthraquinone and methylazoxymethanol acetate.

A rat model for human ulcerative colitis (UC) has been developed by using 1-hydroxyanthraquinone (1-HA) to cause severe inflammation of colonic mucosa. 1-HA also has synergistic effects on the carcinogenicity of methylazoxymethanol (MAM) acetate in the rat colon. In this study, four adenomas and 16 adenocarcinomas induced in male F344 rats by 1-HA and MAM acetate were examined for mutations in the entire coding regions and introns flanking coding exons of the APC gene by polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP) and PCR-restriction-SSCP analyses. No mutations were found. These results, together with our previous observations of a relative lack of Ki-ras gene mutations in the same tumors, are similar to those found in human UC-associated colon cancer, suggest a common pathway in these two systems, although they are different in their implication of p53 mutations. Therefore, this model may have some relevance and application to the study of colon cancer in human inflammatory bowel disease, which is not associated with APC mutations or with Ki-ras or p53 mutations.

Animals↗
PubMed1996

Stac, a novel neuron-specific protein with cysteine-rich and SH3 domains.

In RLGS-M (restriction landmark genomic scanning using methylation-sensitive endonuclease) displays of mouse brains, spot #91 is one of tissue-specific gel spots whose intensity changes developmentally. We have now cloned the corresponding cDNA from this spot and analyzed its structure and expression. The deduced amino acid sequence revealed that the #91 cDNA encodes a novel protein of 403 amino acids which consists of a cysteine-rich domain and a SH3 domain. We designated this gene as Stac. Northern blotting and in situ hybridization analyses demonstrated that 2.7 kb of Stac mRNA is expressed predominantly in brain and neurons, especially in hippocampus, cerebellum and inferior olive. Further, the gene product of 47 kDa was found by western blotting analysis in the soluble fractions of brain as well as Stac-expression vector-transfected NIH3T3 cells. Although the function of Stac is unknown so far, it is likely involved in a neuron-specific signal transduction.

Amino Acid Sequence↗
PubMed1996

Threonine 1342 in human topoisomerase IIalpha is phosphorylated throughout the cell cycle.

To investigate the relationship between the modulation of topoisomerase II activity and its phosphorylation state during the cell cycle, a monoclonal antibody against C-terminal peptide (residues 1335-1350) of topoisomerase IIalpha containing a consensus sequence of casein kinase II, TDDE and its phosphorylated threonine were prepared. In an enzyme-linked immunosorbent assay, the antibody, named PT1342, recognized the immunogenic phosphopeptide but not the non-phosphorylated form of the peptide. The PT1342 antibody reacted only with a 170-kDa protein from HeLa cells and recognized anti-topoisomerase IIalpha immunoprecipitants. Furthermore, the antibody did not react with the human topoisomerase IIalpha mutated at codon 1342 from threonine to alanine, showing that PT1342 was directed against the phosphorylated threonine 1342. To examine the level of phosphorylation of threonine 1342 of topoisomerase IIalpha through the cell cycle, HeLa cells were stained simultaneously for phosphorylated topoisomerase IIalpha and DNA and analyzed by flow cytometry. Cells in the G2-M phase contained about double the PT1341-reacted topoisomerase IIalpha than did cells in G1 or S phases. The antibody stained the nuclei in interphase and mitotic chromosomes and its periphery, as seen with anti-topoisomerase IIalpha antibody. Thus, threonine 1342 in topoisomerase IIalpha is phosphorylated throughout the cell cycle.

Amino Acid Sequence↗
PubMed1996

Chemoprevention of 4-nitroquinoline 1-oxide-induced rat oral carcinogenesis by the dietary flavonoids chalcone, 2-hydroxychalcone, and quercetin.

The modifying effects of dietary exposure of three flavonoids, chalcone, 2-hydroxychalcone, and quercetin, during the initiation and postinitiation phases of oral tumorigenesis initiated with 4-nitroquinoline-1-oxide (4-NQO) were investigated in male F344 rats. At 6 weeks of age, animals were divided into experimental and control groups. At 7 weeks of age, all animals except those treated with test chemicals alone and the untreated control group were given 4-NQO [20 parts/million (ppm)] in the drinking water for 8 weeks to induce oral neoplasms. For chemopreventive study by feeding of test compounds during the initiation phase, groups of animals were given diets containing 500 ppm chalcone, 500 ppm 2-hydroxychalcone, or 500 ppm quercetin for 10 weeks, starting 1 week before 4-NQO exposure. Seven days after stopping 4-NQO exposure, these groups were switched to the basal diet and kept on this diet until the end of the experiment. For chemopreventive study by treatment with test chemicals during the postinitiation phase, starting 1 week after the cessation of 4-NQO administration, the groups given 4-NQO and the basal diet were switched to the diets mixed with test chemicals and maintained on these diets for 22 weeks. The other groups consisted of rats fed diets containing 500 ppm test chemicals alone or of untreated rats. Thirty-two weeks after the start of the study, the incidence of tongue neoplasms and preneoplastic lesions, polyamine levels in the tongue epithelium, and cell proliferation activity estimated by bromodeoxyuridine labeling index were compared among the different dietary groups. Feeding of all test chemicals during either initiation or postinitiation phases caused a significant reduction in the frequency of tongue carcinoma (68-88% reduction; P < 0.05). Dietary administration of these test chemicals also significantly decreased the bromodeoxyuridine labeling index of the tongue squamous epithelium (P < 0.05). In addition, polyamine levels in the oral mucosa were lowered in rats treated with 4-NQO and test chemicals when compared to those given 4-NQO alone. These results indicate that the flavonoids chalcone, 2-hydroxychalcone, and quercetin present in our daily foods have an inhibitory effect on oral carcinogenesis initiated with 4-NQO, and such a modifying effect may be related partly to the suppression of cell proliferation.

4-Nitroquinoline-1-oxide↗
PubMed1996

A microwave-mediated saponification of galactosylceramide and galactosylceramide I3-sulfate and identification of their lyso-compounds by delayed extraction matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

Small amounts of galactosylceramide (cerebroside) and galactosylceramide I3-sulfate (sulfatide) obtained from porcine spinal cord and equine kidney were deacylated by a rapid method of microwave-mediated saponification to prepare their lyso-compounds. Mass spectra of their protonated or deprotonated molecular ion peaks were detected by recently developed new technology of a delayed extraction matrix-assisted laser desorption ionization time-of-flight mass spectrometer with reflector detector in positive or negative ion mode. Long chain bases of lysocerebroside and lysosulfatide were different between porcine spinal cord and equine kidney, but similar to each other in the same organ, suggesting their common synthetic pathway. It is noted that the new rapid method can be similarly applied to the deacylation of both cerebroside and sulfatide in contrast to our classical method which was able to be applied to cerebroside, but not to sulfatide.

Animals↗
PubMed1996

Aldose reductase is a major reductase for isocaproaldehyde, a product of side-chain cleavage of cholesterol, in human and animal adrenal glands.

Isocaproaldehyde (4-methylpentanal) is a product of the side-chain cleavage of cholesterol, the first step of steroid biosynthesis. Here, we report the characterization of enzymes responsible for the oxidoreduction of isocaproaldehyde in human, monkey, dog, and rabbit adrenal glands. NADPH-linked isocaproaldehyde reductase activity in the adrenal extracts of the four species was much higher than the NADH-linked reductase and NAD(P)(+)-linked dehydrogenase activities and was potently inhibited by aldose reductase inhibitors. The major species of isocaproaldehyde reductase purified from the four mammalian adrenal glands were biochemically identical with aldose reductase, and exhibited Km values of 1 microM. The contents of aldose reductase in adrenal glands of the four mammals were relatively high, and its localization in canine adrenal cortex was immunohistochemically demonstrated. In addition, the purified aldose reductases and recombinant human aldose reductase reduced other alkanals and alkenals at low Km values of 2-61 microM, and their catalytic efficiencies were higher than that of human aldehyde reductase. Thus, aldose reductase acts not only as a major reductase for isocaproaldehyde formed from steroidogenesis but also as a scavenger of aldehydes derived from lipid peroxidation in mammalian adrenal glands.

Adrenal Glands↗
PubMed1996

Immunohistochemical detection of Bax and Bcl-2 proteins in gerbil hippocampus following transient forebrain ischemia.

Time-course expression of Bax and Bcl-2 proteins, identified as apoptosis-regulating molecules, was assessed in gerbil hippocampus following transient forebrain ischemia. Brain sections from animals sacrificed at 48, 72, 96 h and 7 days following 5 min ischemia were immunohistochemically evaluated using polyclonal antibodies specific for Bax and Bcl-2 proteins, respectively. The intensity of Bax expression in CA1 neurons increased with time and peaked at 72 h, and immediately disappeared at 96 h following 5 min ischemia. No expression of Bcl-2 in the CA1 neurons was recognized in all the time evaluated.

Animals↗
PubMed1996

Crystal structure of the ternary complex of mouse lung carbonyl reductase at 1.8 A resolution: the structural origin of coenzyme specificity in the short-chain dehydrogenase/reductase family.

BACKGROUND: Mouse lung carbonyl reductase (MLCR) is a member of the short-chain dehydrogenase/reductase (SDR) family. Although it uses both NADPH and NADH as coenzymes, the structural basis of its strong preference for NADPH is unknown. RESULTS: The crystal structure of the ternary complex of MLCR (with NADPH and 2-propanol) has been determined at 1.8 A resolution. This is the first three-dimensional structure of a carbonyl reductase, and MLCR is the first member of the SDR family to be solved in complex with NADPH (rather than NADH). Comparison of the MLCR ternary complex with three structures reported previously for enzymes of the SDR family (all crystallized as complexes with NADH) reveals a pair of basic residues (Lys17 and Arg39) making strong electrostatic interactions with the 2'-phosphate group of NADPH. This pair of residues is well conserved among the NADPH-preferring enzymes of the SDR family, but not among the NADH-preferring enzymes. In the latter, an aspartate side chain occupies the position of the two basic side chains. The aspartate residue, which would come into unacceptably close contact with the 2'-phosphate group of the adenosine moiety of NADPH, is replaced by a threonine or alanine in the primary sequences of NADPH-preferring enzymes of the SDR family. CONCLUSIONS: The cofactor preferences exhibited by the enzymes of the SDR family are mainly determined by the electrostatic environment surrounding the 2'-hydroxyl (or phosphate) group of the adenosine ribose moiety of NADH (or NADPH). Thus, positively charged and negatively charged environments correlate with preference for NADPH and NADH respectively.

1-Propanol↗
PubMed1996

Relationship of human liver dihydrodiol dehydrogenases to hepatic bile-acid-binding protein and an oxidoreductase of human colon cells.

We previously isolated three monomeric dihydrodiol dehydrogenases, DD1, DD2 and DD4, from human liver, and cloned a cDNA (C9) thought to encode DD2, which is identical with those for human bile-acid-binding protein and an oxidoreductase of human colon carcinoma HT29 cells. In the present study we have provided evidence that the C9 cDNA clone encodes DD1, not DD2. A recombinant enzyme expressed from the cDNA in a bacterial system was purified, and its catalytic properties, bile-acid-binding ability and primary sequence were compared with those of the hepatic dihydrodiol dehydrogenases. The results show that DD1 encoded by C9 possesses prostaglandin F synthase activity but low affinity for lithocholic acid, whereas DD2, showing differences of six amino acid residues from the DD1 sequence, exhibited high-affinity binding for the bile acid. Refined relationship between dihydrodiol dehydrogenases and their related proteins of human tissues is proposed.

Amino Acid Sequence↗
PubMed1996

Restriction landmark cDNA scanning (RLCS): a novel cDNA display system using two-dimensional gel electrophoresis.

We have developed a new method, designated restriction landmark cDNA scanning (RLCS), which displays many cDNA species quantitatively and simultaneously as two-dimensional gel spots. In this method cDNA species of uniform length were prepared for each mRNA species using restriction enzymes. After the restriction enzyme sites were radiolabeled as landmarks, the labeled fragments were subjected to high resolution two-dimensional gel electrophoresis. In analyses of cDNA samples from adult mouse liver and brain (cerebral cortex, cerebellum and brain stem) we detected approximately 500 and >1000 discrete gel spots respectively of various intensities at a time. The spot patterns of the three brain regions were very similar, although not identical, but were quite different from the pattern for the liver. RNA blot hybridization analysis using several cloned spot DNAs as probes showed that differences in intensity of the spots among RLCS profiles correlated well with expression levels of the corresponding mRNA species in the brain regions. Because the spots and their intensities reflect distinct mRNA species and their expression level respectively, the RLCS is a novel cDNA display system which provides a great deal of information and should be useful for systematic documentation of differentially expressed genes.

Animals↗
PubMed1996

Activation of human liver 3 alpha-hydroxysteroid dehydrogenase by sulphobromophthalein.

Human liver contains at least two isoenzymes (DD2 and DD4) of 3 alpha-hydroxysteroid/dihydrodiol dehydrogenase. The NADP(H)-linked oxidoreductase activities of DD4 were activated more than 4-fold by sulphobromophthalein at concentrations above 20 microM and under physiological pH conditions. Sulphobromophthalein did not stimulate the activities of DD2 and human liver aldehyde reductase, which are functionally and/or structurally related to DD4. No stimulatory effect on the activity of DD4 was observed with other organic anions such as Indocyanine Green, haematin and Rose Bengal. The binding of sulphobromophthalein to DD4 was instantaneous and reversible, and was detected by fluorescence and ultrafiltration assays. The activation by sulphobromophthalein decreased the activation energy in the dehydrogenation reaction for the enzyme, and increased both kcat, and Km values for the coenzymes and substrates. Kinetic analyses with respect to concentrations of NADP+ and (S)-(+)-indan-1-ol indicated that sulphobromophthalein was a non-essential activator of mixed type showing a dissociation constant of 2.6 microM. Thus, the human 3 alpha-hydroxysteroid dehydrogenase isoenzyme has a binding site specific to sulphobromophthalein, and the hepatic metabolism mediated by this isoenzyme may be influenced when this drug is administered.

3-Hydroxysteroid Dehydrogenases↗
PubMed1996

Telomerase activity of normal tissues and neoplasms in rat colon carcinogenesis induced by methylazoxymethanol acetate and its difference from that of human colonic tissues.

Telomerase activity in tissues may be related to tumor development, especially malignant conversion, in humans. However, there are few reports about telomeres and telomerase activity in animals. In this study, we examined telomerase activity in rat colon carcinogenesis and in normal rat liver tissue and compared it with that of human colon cancer tissues. This is the first report concerning telomerase activity in rats. F344 rats were used, and colon neoplasms were induced with methylazoxymethanol acetate. There was telomerase activity in not only the induced colon neoplasms but also the colon mucosa and livers of untreated rats, in contrast with the results from normal human somatic tissues in previous reports. Indeed, we also observed negative results in normal human mucosa, despite the positive results in colon-cancer tissues. These findings suggest that there is a difference in the telomerase activities in humans and rats. Because rat telomeres are very long (20-100 kp, average 50 kp) compared with human telomeres (5-15 kp, average 12 kp), the difference in the telomere lengths of rats and humans might be related to their enzyme activities, although this is still unclear. Furthermore, because the inhibition of telomerase has been proposed as a novel cancer therapy for humans, the rat model presented here, in which telomerase is expressed in somatic tissues, may be useful for studies of telomerase inhibition, including inhibition by chemopreventive agents.

Adenocarcinoma↗
PubMed1996

Role of the sympathetic nervous system in the ischemic and reperfused heart.

Norepinephrine, that has been released from sympathetic nerve endings in response to myocardial ischemia, may have either a beneficial or a harmful effect on the ischemic heart. If the duration of ischemia is short, the release of norepinephrine may be favorable for the production of energy and for protection of the heart against ischemic damage. If the duration of ischemia is prolonged, there is a marked increase in number of both alpha 1 and beta-adrenoceptors located in the sarcolemmal membrane, as well as an excessive increase in release of norepinephrine. These events during the prolonged period of ischemia can produce an imbalance between oxygen supply and demand, which is harmful to the heart. The anti-ischemic effect of alpha 1- and beta-adrenoceptor antagonists is not attributed merely to improvement of oxygen balance, but reduction of phospholipase activity or stabilization of membrane may also be important as an underlying mechanism.

Adrenergic alpha-Antagonists↗
PubMed1996

Localization of Bax and Bcl-2 proteins, regulators of programmed cell death, in the human central nervous system.

Bax and Bcl-2 proteins are identified as regulating molecules for programmed cell death. In the central nervous system, programmed cell death or apoptosis is considered to be an important phenomenon that is related to neuron vulnerability to a variety of toxic effects, including ischaemic insult. In this study, localization of Bax and Bcl-2 proteins was investigated in the human central nervous system using autopsy cases without any neurological disorder. Results were compared with findings in the rat. Most neurons in human cerebral cortex, basal ganglia and brain stem were positive for both Bax and Bcl-2 proteins, whereas Purkinje cells in cerebellum and neurons in hippocampal CA1, CA2 and CA3 regions were positive for Bax but negative or weakly positive for Bcl-2. Glial cells examined in all sections were negative for both proteins. Choroid plexus, ependymal cells and arachnoid villi showed positive reactivity for both proteins. A possible relationship between the localization of Bax or Bcl-2 proteins and the cell vulnerability in central nervous system is discussed.

Animals↗
PubMed1996

Sulfatide prolongs blood-coagulation time and bleeding time by forming a complex with fibrinogen.

Sulfatides (galactosylceramide I3-sulfate), which are found in serum lipoproteins of various mammals, effectively increased prothrombin time (anticoagulant effect) and also effectively prolonged bleeding time (anti-platelet effect). When equal volumes of a homogeneous micellar solution of sulfatide and fibrinogen in phosphate-buffered saline were mixed, an insoluble complex precipitated. Analysis of the precipitated complex showed that the molar ratio of sulfatide to fibrinogen was about 400:1. These results indicate that the sulfatide micelle binds tightly to fibrinogen and thereby interferes with both fibrin gel formation (anticoagulant activity) and platelet function.

Animals↗