Exact-diagonalization study of the Hubbard model with nearest-neighbor repulsion.
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Journal Article↗
Biomedical subjects
K Tsutsui
Publications and source records attributed to K Tsutsui.
Differential changes in the activities of multiple protein kinase C subspecies in the hippocampal-kindled rat.
In previous studies we demonstrated that the membrane-associated protein kinase C (PKC) activities in the right and left hippocampus (HIPP) of rats kindled from the left HIPP increased significantly 4 weeks and 4 months after the last seizure compared with those in matched control rats. In this study, we investigated the long-lasting effect of HIPP-kindling on the membrane-associated activities of PKC subspecies in the bilateral HIPP 1 and 4 weeks after the last generalized kindled seizure had occurred. The membrane-associated activities of PKC subspecies were found to be subject to differential regulation. The activity of the alpha-subspecies was unchanged, whereas the respective activities of the beta- and gamma-subspecies in the kindled group increased significantly, compared with the controls, one (21%, P < 0.0001 for the beta-subspecies, and 23%, P < 0.001 for the gamma-subspecies) and 4 weeks (19%, P < 0.02 for the beta-subspecies, and 19%, P < 0.05 for the gamma-subspecies) after the last seizure. There were no significant differences in cytosolic PKC activity between the control and kindled groups for any subspecies examined at either time after the last seizure. These results suggest that activation of the PKC beta- and gamma-subspecies may play an important role in the enduring seizure susceptibility associated with kindling.
Animals↗
Detection of endogenous albumin as an index of blood parenchymal border alteration.
We used a microdialysis technique to establish a method to detect sequential changes in disruption of the blood parenchymal border. Twelve cats were divided into two groups; one group underwent occlusion of the middle cerebral artery for 60 minutes, the other a cold injury model. Microdialysis probes were implanted bilaterally into the white matter, and dialysates were collected successively at 30 minute intervals for 6 hours in the occlusion model and 4 hours in the cold injury model. Regional cerebral blood flow was measured simultaneously using the hydrogen clearance method. The water content of the white matter was measured using specific gravity. The proteins in the dialysate were analyzed using electrophoresis with silver stain, and, with densitometric analysis, the density of the 66.2 kDa band was quantified as albumin. The ratio of this density to the preoperative density was defined as the "albumin index." On the side of the lesion in the cold injury model, this index significantly increased 3 hours after the cold injury compared with the contralateral side, and a correlation between the water content and this index was observed. The albumin index was believed to indicate the severity of disruption of the blood parenchymal border.
Animals↗
Differential expressions of the topoisomerase II alpha and II beta mRNAs in developing rat brain.
Distributions of the topoisomerase II alpha and II beta mRNAs were examined in the developing rat brain, by in situ hybridization with isoform-specific oligonucleotide probes. Intense signals for the topoisomerase II alpha mRNA were detected in the ventricular zone of each brain region at embryonic day 13-15 (E13-E15), and in the external granular layer of the cerebellum at postnatal day 7-14 (P7-P14). Thereafter, the signals rapidly decreased in levels and eventually disappeared from respective regions. Administration of bromodeoxyuridine (BrdU) into embryos at E13 showed that the topoisomerase II alpha mRNA was expressed in the BrdU-incorporated region and its ventricular side of the neural wall, suggesting that transcription of this isoform occurs in neurons from S-phase through M-phase. On the other hand, the topoisomerase II beta mRNA was distributed throughout the brain from E13 through P21, irrespective of the ventricular and mantle zones. Signal levels of the topoisomerase II beta mRNA were much stronger during early developmental stages than at mature stages in various brain regions. The characteristic and differential spatio-temporal expressions suggest that the topoisomerase II alpha is involved in the proliferation, while the topoisomerase II beta is closely related to differentiation and maturation of neurons.
Aging↗
Annular elastolytic giant cell granuloma: response to cyclosporin A.
A case of annular elastolytic giant cell granuloma with a good response to cyclosporin A is reported. A 62-year-old man developed multiple annular patches on the trunk with elevated and indurated borders. Biopsy specimens from the border showed granulomatous inflammation in the mid dermis with phagocytosis of elastic fibers by giant cells. Biopsy specimens from the center showed dense collagen formation without inflammation. Immunological investigation of perivascular infiltrating cells in the lesions revealed a predominance of CD4+ cells over CD8+ cells. Our case showed a good response to cyclosporin A (5 mg/kg/day) for eight weeks. There were no adverse effects and no recurrences for one month after discontinuation of cyclosporin A.
Cyclosporine↗
Molecular cloning of partial cDNAs for rat DNA topoisomerase II isoforms and their differential expression in brain development.
cDNA segments for DNA topoisomerase II were amplified from rat brain RNA after reverse transcription by the polymerase chain reaction, using degenerate oligonucleotide primers deduced from the conserved regions of topoisomerase II of higher eukaryotes. The cDNA product from a successful amplification was homogeneous in length but heterogeneous in sequence. Restriction mapping of the cloned cDNA fragments revealed that they consisted of two distinct sequence groups. DNA sequencing of representative clones from each group, designated A and B, showed that they are highly homologous to cDNAs of human topoisomerase II isoforms, alpha and beta, respectively. Northern blot analysis indicated that the transcript level for rat topoisomerase II alpha was high in embryonic brain and in the cerebellum of 2-day newborns, followed by rapid decrease to a undetectable level at 4 weeks after birth. In contrast, rat topoisomerase II beta transcript was present throughout the embryonic and postnatal stages. In the developing cerebellum, cells expressing topoisomerase II alpha were confirmed exclusively to the outer mitotic zone of the external granular layer, whereas the transcript of topoisomerase II beta was detected over the entire cortical region. These results clearly indicate that the isoform alpha is expressed only in proliferating cells. The differential expression of topoisomerase II isozymes was also observed among developed tissues. Therefore, the isozymes are most likely to be involved in the following different physiological processes: topoisomerase II alpha in cell proliferation, and topoisomerase II beta in some processes unrelated to cell proliferation.
Amino Acid Sequence↗
Activity gel and activity blotting methods for detecting DNA-modifying (repair) enzymes.
Zymographical methods (activity gel, overlay gel, activity blot and activity blotting) for detecting DNA-modifying (repair) enzymes are reviewed. Emphasis is put on the novel activity blotting method in which DNA repair enzymes electrophoresed on a gel are blotted and detected on a damaged DNA-fixed nylon membrane. Its practical procedures, including a non-radioactive detection procedure, and representative results are also described.
Animals↗
Identification and characterization of a nuclear scaffold protein that binds the matrix attachment region DNA.
The association of nuclear DNA with the nuclear matrix (scaffold) is mediated by defined segments of DNA called matrix association region (MAR). By using a plasmid harboring a portion of the Ig kappa gene within which MAR had been located, we searched for proteins recognizing MAR in the nuclear scaffold components electrophoretically separated and blotted onto a membrane. In the presence of nonspecific competitor DNA, the labeled plasmid selectively bound to a protein with apparent molecular weight of 120,000 (designated SP120). The protein was purified directly from SDS-polyacrylamide gels and renatured by a guanidine hydrochloride procedure. The DNA region in the plasmid responsible for the binding to the solubilized SP120 coincided with the 365-base pair HindIII-HinfI fragment that had been identified as MAR. In solution, SP120 exhibited a cooperative mode of interaction with the end-labeled MAR fragment. Measurement of relative affinities of MAR subfragments to SP120 showed that the whole region is required for efficient binding. This is consistent with the minimal length for MAR estimated thus far by in situ mapping experiments. The MAR derived from another gene, fushitarazu, also bound specifically to SP120. Immunostaining of whole cells and isolated nuclei with a monoclonal antibody raised against SP120 indicated that the protein is localized in a nuclear skeletal structure. These results suggest the involvement of SP120 in the MAR-mediated anchorage of nuclear DNA to the nuclear scaffold.
Animals↗
Photoperiodic regulation of follicle-stimulating hormone binding to gonads and of plasma gonadotropin concentrations in Indian weaver birds.
Previous studies showed that changes of gonadal weight and of follicle-stimulating hormone (FSH) receptor number in response to fluctuations in natural environmental conditions are smaller in female than in male Indian weaver bird (Ploceus phillippinus). Therefore, we studied whether the response to artificial photoperiodic changes differs between the sexes. Birds were transferred to short-day (SD) photoperiods during the breeding phase (June). Other birds were subjected to long-day (LD) photoperiods during the nonbreeding phase (December). Exposure to SD for 10 weeks induced a marked testicular weight decrease. Similarly, FSH binding per unit testicular weight as well as per two testes decreased after SD exposure. The influence of photoperiodic manipulations on the ovarian weight was much smaller than that on the testicular weight. SD exposure did not alter FSH binding either per unit ovarian weight or per ovary. Plasma gonadotropin concentration significantly decreased in both sexes subjected to SD environment. On the other hand, exposure to LD significantly increased testicular weight. LD exposure slightly increased ovarian weight, but the increase was statistically not significant. FSH binding per unit testicular weight markedly increased 10 weeks after transfer to LD. The total FSH binding per two testes showed a parallel change with the testicular weight. However, there was no significant increase in FSH binding per unit ovarian weight during 10 weeks of LD exposure. Although LD exposure for 10 weeks significantly increased the total FSH binding per ovary, the rate of increase was much smaller than that in the testes. The plasma gonadotropin level in both sexes was increased by LD exposure. Scatchard plot analyses of FSH binding indicated that FSH binding changes were due to changes in binding site number. These results suggest that photoperiod regulates FSH receptor numbers particularly in the testis. Such an effect is manifested by marked changes in the testicular weight under different photoperiodic conditions in the subtropical bird.
Animals↗
[Interaction of DNA with nuclear skeletal structures].
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Binding Sites↗
Coagulation-fibrinolysis system and markers of collagen metabolism in lung cancer.
BACKGROUND: Evidence suggests that the fibrinolysis system and peritumoral connective tissue play important roles in tumor spread. METHODS: In this study, the authors evaluated the following parameters in 30 consecutive patients with lung cancer: thrombin-antithrombin complex (TAT), cross-linked fibrin split products D-dimer (DD), plasmin-alpha 2-antiplasmin inhibitor complex (PAP), and two antigens related to connective tissue, the aminoterminal propeptide of type III procollagen (PIIIP) and the 7S domain of type IV collagen (7S-collagen). RESULTS: Each parameter was increased significantly in the patients with cancer compared with the control subjects. Except for PIIIP, their concentration in blood was elevated to a significantly greater extent in the patients with distant metastases. The PAP concentration correlated well with the plasma concentration of TAT (r = 0.5; P < 0.01) and DD (r = 0.9; P < 0.0001). There was also a strong correlation between the serum concentrations of PIIIP and 7S-collagen (r = 0.7; P < 0.001). In patients with localized disease, DD levels were correlated significantly with those of PIIIP (Spearman rank-order correlation [rs] = 0.6; P < 0.025) and 7S-collagen (rs = 0.6; P < 0.01). In the group with disseminated metastases, there was a significant inverse relationship between serum PAP concentrations and serum concentrations of 7S-collagen (rs = -0.6; P < 0.025). CONCLUSIONS: These results confirm the presence of a subclinical chronic activation of the parameters of intravascular clotting-fibrinolysis and alterations in the extracellular matrix of patients with lung cancer. These parameters may be useful as indicators of the clinical progression of malignant disease, particularly of lung cancer.
Adult↗
Evolution of the in-gap state in high-Tc cuprates.
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Journal Article↗
Inhibitory role of sex steroid in the regulation of ovarian follicle-stimulating hormone receptors during pregnancy.
The present study was conducted to determine the role of sex steroids in the regulation of FSH receptors in pregnant rats. In the normal physiological condition, FSH bindings per unit ovarian weight (density of binding) and per 2 ovaries (total binding) increased during days 14-21 gestation. Scatchard plot analyses of the binding suggested that the increase in FSH binding was due to an increase in the number of FSH-binding sites. The plasma FSH concentration in pregnant rats was stable during the receptor change. In contrast, the plasma estradiol-17 beta concentration continuously increased from gestation day 14 to 21, and the testosterone level showed a large peak on gestation day 18. Estradiol-17 beta (one silastic plate containing 13 mg crystal)-implanted pregnant rats during 14-21 days of gestation induced significant decreases in the total FSH binding and ovarian weight on gestation day 21. Estradiol administration increased the plasma estradiol level 2.3-fold but did not change the FSH level. Testosterone or 5 alpha-dihydrotestosterone, a nonaromatizable androgen, did not influence the binding level under the same dose treatment. In contrast, continuous treatment with aminoglutethimide (2 plates containing 20 mg crystal), an inhibitor of adrenocortical steroidogenesis, for 7 days significantly increased the total FSH binding without a significant change in the ovarian weight. The plasma titers of estradiol and testosterone in pregnant rats treated with aminoglutethimide were reduced by 37% and 51%, respectively. Aminoglutethimide did not influence plasma FSH levels. These results suggest that circulating estradiol acts as a negative factor in the regulation of ovarian FSH receptors, at least during the second half of pregnancy. Other factor(s) that is (are) independent of sex steroids and FSH may contribute to FSH receptor induction.
Aminoglutethimide↗
cDNA cloning, sequencing, expression and possible domain structure of human APEX nuclease homologous to Escherichia coli exonuclease III.
cDNA encoding the human homologue of mouse APEX nuclease was isolated from a human bone-marrow cDNA library by screening with cDNA for mouse APEX nuclease. The mouse enzyme has been shown to possess four enzymatic activities, i.e., apurinic/apyrimidinic endonuclease, 3'-5' exonuclease, DNA 3'-phosphatase and DNA 3' repair diesterase activities. The cDNA for human APEX nuclease was 1420 nucleotides long, consisting of a 5' terminal untranslated region of 205 nucleotide long, a coding region of 954 nucleotide long encoding 318 amino acid residues, a 3' terminal untranslated region of 261 nucleotide long, and a poly(A) tail. Determination of the N-terminal amino acid sequence of APEX nuclease purified from HeLa cells showed that the mature enzyme lacks the N-terminal methionine. The amino acid sequence of human APEX nuclease has 94% sequence identity with that of mouse APEX nuclease, and shows significant homologies to those of Escherichia coli exonuclease III and Streptococcus pneumoniae ExoA protein. The coding sequence of human APEX nuclease was cloned into the pUC18 SmaI site in the control frame of the lacZ promoter. The construct was introduced into BW2001 (xth-11, nfo-2) strain and BW9109 (delta xth) strain cells of E. coli. The transformed cells expressed a 36.4 kDa polypeptide (the 317 amino acid sequence of APEX nuclease headed by the N-terminal decapeptide derived from the part of pUC18 sequence), and were less sensitive to methylmethanesulfonate and tert-butyl-hydroperoxide than the parent cells. The N-terminal regions of the constructed protein and APEX nuclease were cleaved frequently during the extraction and purification processes of protein to produce the 31, 33 and 35 kDa C-terminal fragments showing priming activities for DNA polymerase on acid-depurinated DNA and bleomycin-damaged DNA. Formation of such enzymatically active fragments of APEX nuclease may be a cause of heterogeneity of purified preparations of mammalian AP endonucleases. Based on analyses of the deduced amino acid sequence and the active fragments of APEX nuclease, it is suggested that the enzyme is organized into two domains, a 6 kDa N-terminal domain having nuclear location signals and 29 kDa C-terminal, catalytic domain.
Amino Acid Sequence↗
Induction of interdigitating reticulum cell-like differentiation in human monocytic leukemia cells by conditioned medium from IL-2-stimulated helper T-cells.
Monocytic leukemia (MoL) cells were obtained from the peripheral blood of a patient in whom the leukemic cells infiltrating various lymphoreticular organs exhibited features intermediate between interdigitating reticulum cells (IDC) and ordinary phagocytic macrophages, whereas the leukemic cells in the peripheral blood were essentially monocytic and lacked such features. Peripheral blood CD4+ T-cells were established as an interleukin-2-dependent T-cell line. When the MoL cells were exposed for a few days to conditioned medium from the T-cell line, they extended several dendritic cytoplasmic projections and became intensely positive for HLA-DR antigen, cytoplasmic S-100 beta protein, and CD1 antigen. Functionally, the conditioned medium significantly down-regulated Fc-mediated and Fc-independent phagocytic activities, and the levels of lysosomal enzymes such as lysozyme and nonspecific esterase in the MoL cells. Moreover, the conditioned medium significantly up-regulated the accessory cell function of the MoL cells as measured by the primary allogenic mixed leukocyte reaction (MLR). Furthermore, the conditioned medium significantly down-regulated the expression of CD14 antigen. Biochemical analysis indicated that the factor responsible for these changes is a protein which is distinct from known human cytokines and whose molecular weight is approximately 31 kDa. These findings suggest that IDC are closely related the monocytic lineage and that helper T-cells play an important role in constructing the microenvironment of T-lymphoid tissues which is necessary for the differentiation and maturation of IDC.
Adult↗
Mechanism of induction of cellular DNA synthesis by the adenovirus E1A 12S cDNA product.
The mechanism of induction of DNA synthesis in quiescent rat 3Y1 cells by the adenovirus E1A gene was investigated using the 3Y1 derivative cell lines g12-21, gn12RB1, and gn12RB2. The g12-21 cells express the E1A 12S cDNA and the latter two cells express both the E1A 12S cDNA and the human retinoblastoma susceptibility (Rb) gene at different levels in response to dexamethasone (dex). The cDNA sequences of E1A-inducible cell cycle-dependent genes, clone 3 and clone 16, were isolated by differential screening of a cDNA library constructed from dex-treated g12-21 cells. The quiescent 3Y1 cells induced c-fos and c-myc expression within 2 h after serum stimulation and expressed clone 16 and clone 3 transiently at around 8 h before the onset of DNA synthesis (10 h). In contrast, the quiescent g12-21 cells treated with dex expressed a high level of E1A at 6 to 8 h after treatment and expressed clone 16 and clone 3 at around 8 h without stimulation of c-fos and c-myc expression, suggesting that E1A bypasses the cell cycle early in G1. The half-maximal rate of DNA synthesis was reached in a much shorter time in dex-treated g12-21 cells (12 h) than in serum-treated 3Y1 cells (18 h), suggesting that E1A also bypasses the cell cycle at the G1/S boundary. The gn12RB1 and gn12RB2 cells were unable to induce DNA synthesis in response to dex presumably due to lower levels of E1A expression, although gn12RB2 but not gn12RB1 cells could express clone 16 and clone 3. These results suggest that the level of E1A required for bypass at the G1/S boundary is higher than that required early in G1.
Adenovirus Early Proteins↗
Annual changes in the binding of follicle-stimulating hormone to gonads and plasma gonadotropin concentrations in Indian weaver birds inhabiting the subtropical zone.
In birds, annual changes in gonadal weight are much more pronounced in the male than in the female. To analyze the mechanism inducing such a sex difference in the gonadal responsiveness to natural environmental conditions, we measured annual changes in the binding of follicle-stimulating hormone (FSH) to the gonads and the plasma gonadotropin concentration in adult Indian weaver birds inhabiting the subtropical zone. The binding of FSH was highly specific for mammalian FSHs and located primarily in the gonad. The testicular weight and FSH binding showed marked changes during the annual breeding cycle. The testicular weight was maximal in the breeding phase (June, 1987) and minimal in the nonbreeding phase (December, 1987). FSH binding per unit testicular weight was greatest in the nonbreeding phase, while the total FSH binding per two testes was maximal in the breeding phase and minimal in the regressive phase (October, 1987). In contrast, the changes in the ovarian weight and FSH binding to the ovary were less pronounced than those in the testis. Although FSH binding per unit ovarian weight showed a peak in the nonbreeding phase, there was no significant change in the total FSH binding per ovary during the year, indicating the presence of a clear sex difference in the total FSH binding. Scatchard plot analyses of the binding suggested that the dissociation constant (Kd) ranged from 0.35 to 1.53 nM regardless of sex and season and that the changes in FSH binding were due to changes in the number of binding sites. Plasma FSH and luteinizing hormone (LH) levels markedly changed during the year in both sexes. Both FSH and LH levels were maximal in the breeding phase and minimal in the nonbreeding phase regardless of sex, although the rate of change in either hormone tended to be greater in the male than in the female.
Animals↗
Detection and analyses by gel electrophoresis of cisplatin-mediated DNA damage.
DNA damage induced by cis-diamminedichloroplatinum (II) (cisplatin: cis-DDP), an anticancer drug, was studied in vitro by monitoring the drug-induced conformational change of pUC18 plasmid DNA, the sensitivity to some restriction enzymes of the damaged DNA and the sequence-dependent termination of DNA synthesis caused by cisplatin. Closed circular, superhelical pUC18 DNA was treated at 37 degrees C for 16 h with various concentrations of cisplatin. Cisplatin-dose-dependent conformational change due to unwinding of the treated DNA was detected by agarose gel electrophoresis. To analyze the base-specificity of the cisplatin damage, the measurement for sensitivity of cisplatin-treated DNA to various types of restriction enzyme and sequence gel analysis of the treated DNA were conducted. The results suggested that cisplatin attacked preferentially the sequence of GG > AG > GNG in the order. In the present assay condition, the cisplatin/DNA nucleotide ratios required for the DNA damage detection were roughly 0.025 for the conformational analysis, 0.001 or more for the restriction enzyme analysis, and less than 0.001 for the sequence gel analysis. By using the present method, it was demonstrated that the cisplatin-mediated DNA damage was inhibited by NaCl, KCl, CaCl2 or MgCl2 at their nearly physiological concentrations, and by reducing agents such as thiourea and 2-mercaptoethanol in the reaction mixture.
Base Sequence↗