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Biomedical subjects

K Nagata

Publications and source records attributed to K Nagata.

At least 541 records · Page 30Linked to original sources
PubMed1994

[Some consideration about cerebellar ataxia and crossed cerebellar diaschisis in Dejerine-Roussy syndrome].

We report a 68-year-old right-handed male who exhibited Dejerine-Roussy syndrome including a persistent cerebellar ataxia following the left thalamic hemorrhage with special reference to the evolution of crossed cerebellar diaschisis (CCD) measured with positron emission tomography (PET). The initial PET studies performed 50 days after onset revealed a mild reduction of blood flow and glucose metabolism in the right cerebellar hemisphere in addition to the severe reduction in the left thalamus. Even in the chronic stage when the motor weakness almost disappeared, he persistently showed a cerebellar ataxia in his right extremities. The cerebellar blood flow and metabolism became normalized without laterality in the follow-up PET studies which were performed 29 months after onset, although the left thalamus and left cerebral cortices were still severely involved. The cerebellar ataxia with preserved cerebellar blood flow and metabolism following the thalamic hemorrhage was possibly associated with damage to the efferent fibers from the cerebellum, whereas the CCD observed in the early stage probably was caused by a transient involvement of the cortico-ponto-cerebellar tract at the level of the internal capsule.

Aged↗
PubMed1994

Cerebral uptake of 99mTc-bicisate in patients with cerebrovascular disease in comparison with CBF and CMRO2 measured by positron emission tomography.

The regional brain uptake of 99mTc-N,N'-(1,2-ethylenediyl)bis-L-cysteine diethyl ester (99mTc-bicisate) measured by single photon emission computed tomography (SPECT) was compared with the regional CBF and CMRO2 measured by positron emission tomography in patients with cerebrovascular disease. Nine patients with the diagnosis of cerebral ischemic disorders (n = 7) or cerebral hemorrhage (n = 2) were studied. 99mTc-Bicisate brain uptake correlated with CBF and CMRO2. However, 99mTc-bicisate uptake did not reflect CBF in the single lesion showing luxury perfusion, which seemed to resemble a CMRO2 image. Though quantitative analysis showed the nonlinear correspondence of 99mTc-bicisate brain uptake with CBF and CMRO2, this correspondence could be corrected into a more linear relationship using a correction factor. 99mTc-Bicisate washout from the brain had no correlation to CBF and CMRO2. This diffuse decreasing washout rate was approximately 15% during the first hour after injection. By using the lipophilic fraction of arterial blood and a linearized correction of 99mTc-bicisate SPECT images, the feasibility of obtaining a factor-related CBF and CMRO2 was suggested from our data. These results suggested that 99mTc-bicisate had good characteristics for routine clinical use with SPECT to display the brain function in patients with neurological disorders.

Aged↗
PubMed1994

[Short-term intensive consolidation chemotherapy in the treatment of acute nonlymphocytic leukemia].

Thirty-four adults with AML were treated with conventional remission induction chemotherapy consisting of Ara-C and daunorubicin. The median age was 55 years. Thirty (88%) patients showing complete remission (CR) were treated with four courses of intensive consolidation chemotherapy: course 1 with 7 days Ara-C and 4 days of mitoxantrone; course 2 and 7 days Ara-C, 5 days of etoposide, vincristine day 10 and vinblastine day 12 (A-Triple-V); course 3 with 7 days Ara-C and 3 days of aclacinomycin; course 4 with 7 days Ara-C and 3 days of daunorubicin. Then patients were observed without further therapy until relapse. The median duration of relapse-free survival for patients < 60 years of age was 13 months, with 49% patients projected to continue first CR at 52 months. In contrast, only 19% of patients 60 years or older were projected to be in CR at 22 months. Most patients experienced significant side effects including fever, liver dysfunction, pneumonia and septicemia during consolidation therapies. Short-term intensive consolidation therapy appeared to be efficacious for patients < 60 years of age. The results in older individuals were worse than expected, and the use of G-CSF was suggested to improve this problem.

Aclarubicin↗
PubMed1993

Isolation and expression of a cDNA encoding a male-specific rat sulfotransferase that catalyzes activation of N-hydroxy-2-acetylaminofluorene.

A cDNA (ST1C1 cDNA) encoding a N-hydroxyarylamine sulfotransferase (HAST-I) was isolated from a liver cDNA library of a male adult rat and was expressed in COS-1 cells. ST1C1 cDNA (1363 base pairs) encoded a protein of 304 amino acids with a molecular mass of 35,768 daltons, which shared 50.7 and 46.1% sequence identity with rat aryl (ST1A1 (PST-1)) and estrogen (rOST) sulfotransferases, respectively. N-terminal amino acid sequences of three digested polypeptide fragments of HAST-I were completely identical with two portions of the ST1C1 amino acid sequence. The profile of age- and sex-related expression of ST1C1 mRNA was quite consistent with changes in the sulfating activity of N-hydroxyarylamine and HAST contents in rat livers. ST1C1 expressed in COS-1 cells catalyzed a sulfation of N-hydroxy-2-acetylaminofluorene (N-OH-AAF) at a rate of 4.98 nmol/mg of protein/min and mediated PAPS (3'-phosphoadenosine-5'-phosphosulfate)-dependent DNA binding of N-OH-AAF. Although ASTIV was believed to be responsible for the activation of N-OH-AAF, ST1A1 encoding an arylsulfotransferase ASTIV, showed only a marginal activity in a sulfation and covalent binding of N-OH-AAF. These data clearly indicate that ST1C1 cDNA codes a new form of a male-dominant sulfotransferase (HAST) responsible for the bioactivation of N-hydroxyarylamines in rat livers.

Amino Acid Sequence↗
PubMed1993

Plasminogen-binding protein associated with the plasma membrane of cultured embryonic rat neocortical neurons.

To investigate the receptor-like molecule(s) for plasminogen (PGn) on the neuronal surface, the properties of binding of PGn to the plasma membrane of cultured embryonic rat neocortical neurons were investigated. [125I]PGn was found to specifically bind to the plasma membrane depending on the incubation temperature and time. The binding was also affected strongly by ionic strength and slightly by Ca2+. Furthermore, ligand blotting analysis revealed that [125I]PGn binds to a major protein with an apparent molecular weight of 45 kDa among plasma membrane proteins. These results suggest that the 45-kDa protein is a PGn receptor-like molecule on the neuronal surface.

Animals↗
PubMed1993

Plasminogen promotes the development of rat mesencephalic dopaminergic neurons in vitro.

In order to investigate the physiological significance of plasminogen, which is produced by and secreted from microglia, we determined the effects of plasminogen on the development of primary cultured mesencephalic neurons from 16-day-old embryonic rats. Plasminogen markedly increased dopamine uptake and the dopamine content of cultured neurons. Furthermore, the number of mesencephalic dopaminergic neurons, which was determined by immunostaining with tyrosine hydroxylase antibody, was significantly increased in the presence of plasminogen. However, plasminogen had only a slight effect on gamma-aminobutyric acid (GABA) uptake and glutamic acid decarboxylase activity in mesencephalic neurons. The effect on dopaminergic neurons was also observed in the culture in the presence of cytosine arabinoside. In addition, plasminogen had no effect on the number of glial fibrillary acidic protein-positive cells. These results suggest that plasminogen acts directly on neurons and enhances the development of dopaminergic neurons in a rather selective manner.

Animals↗
PubMed1993

Subcellular localization of a low Mr GTP-binding protein, c25KG, in resting and stimulated human platelets.

Subcellular fractions were prepared from human platelets by sucrose density gradient centrifugation and the presence of a GTP-binding protein, c25KG, was analyzed by immunoblotting. c25KG was found to be located in plasma membrane and alpha-granule fractions in resting platelets by immunoblot analysis. Disappearance of the protein by the pronase treatment of intact alpha-granules indicated that c25KG is exposed on the cytoplasmic face of the granules. Activation of platelets by thrombin induced the redistribution of c25KG from alpha-granules to plasma membranes. On the other hand, Gi2, which is the main pertussis toxin-substrate in human platelets, was predominantly present in plasma membranes and thrombin-stimulation did not alter its distribution.

Blood Platelets↗
PubMed1993

Activated platelets induce superoxide anion release by monocytes and neutrophils through P-selectin (CD62).

Activated platelets expressing P-selectin in their surfaces are known to adhere to monocytes and neutrophils. We examined the possibility that the leukocytes are functionally modified by their adhesion to activated platelets. We used human peripheral blood monocytes and neutrophils and measured superoxide anion generation by these cells cultured with platelets. The levels of superoxide anion production were found to be markedly elevated when thrombin-activated platelets were used. The extent of this enhancement was much smaller when leukocytes were cultured with resting platelets than activated platelets. The increase depended on incubation time and platelet concentration. The membranes prepared from activated platelets also induced superoxide anion production, but the culture supernatant of activated platelets did not. The enhanced superoxide anion production was inhibited by anti-P-selectin antibody, anti-sialyl-Lewis X antibody, or a soluble recombinant P-selectin fusion protein. These results indicate that the adhesion of activated platelets to the leukocytes through P-selectin was a crucial step for the activation of leukocyte function, and support the idea that activated platelets are actively involved in inflammation processes.

Base Sequence↗
PubMed1993

Structure of mouse Mx1 protein. Molecular assembly and GTP-dependent conformational change.

Mouse Mx1 protein is an interferon-inducible nuclear protein and confers resistance to influenza virus infection. The Mx1 protein purified from interferon-induced A2G mouse liver exhibited GTPase activity as did the Mx1 protein purified from the Mx1 cDNA-expressing Escherichia coli (Nakayama, M., Nagata, K., Kato, A., and Ishihama, A. (1991) J. Biol. Chem. 266, 21404-21408; Nakayama, M., Nagata, K., and Ishihama, A. (1992) Virus Res. 22, 227-234). The Mx1 protein purified from both mouse liver and Mx1-cDNA expressing E. coli was found to exist as assembled polymeric states judged from gel filtration pattern. By making a set of deletion derivatives of the Mx1 cDNA, the main motif for self-assembly of the Mx1 protein was mapped between amino acid residues 51-99. This motif is highly conserved not only in the Mx family of proteins but also in Mx-related proteins. The polymeric form of Mx1 from E. coli was observed as "horseshoe"-like structure by negative staining microscopy. When the Mx1 protein was incubated with GTP, this horseshoe structure was transformed to larger and tightly stacked helical forms. Electron microscopic analysis of immunostained liver of the interferon-induced mice indicated that the Mx1 protein exists in nuclei, forming giant complexes of about half the size of nucleoli.

Amino Acid Sequence↗
PubMed1993

Ischemic tolerance due to the induction of HSP70 in a rat ischemic recirculation model.

Various studies have demonstrated an increase in heat shock protein 70 (HSP70) synthesis in the brain following transiently induced ischemia, suggesting a protective role for HSP70 against ischemic insult. In this study, we determined the time course of HSP70 mRNA and protein induction in rat hippocampus following ischemia using Pulsinelli's four-vessel occlusion model, and suggested a protective role for HSP70 induction in limiting ischemic damage to neurons and delayed neuronal death. In Northern blotting analysis using human HSP70 DNA as a probe, the accumulation of HSP70 mRNA after 5 min ischemia became evident at 4 h, and continued until 16 h, while after 30 min ischemia, HSP70 mRNA appeared at 2 h, and continued above control level until 24 h after treatment. In immunoblot analysis using anti-HSP70 antibody, induction of HSP70 protein appeared 24 h and reached a maximum 48 h after 5 min ischemia. In immunohistochemical analysis using anti-HSP70 antibody, staining was not detected in CA1 neurons until 16 h after 5 min ischemia, but staining in CA1 gradually increased 1 day after ischemia and reached a maximum level 2 days after ischemia. Similar time profiles in the staining pattern of HSP70 protein were observed in CA3 and CA4 neuronal cells following 30 min ischemia. When rats pretreated with 5 min ischemia (non-lethal for CA1 pyramidal neurons) were exposed to a 30 min, lethal period of ischemia, 2 days after pretreatment, considerable staining of HSP70 was observed. Pretreated rats had much less neuronal damage in the CA1 sector than did rats subjected to lethal, 30 min ischemia alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗
PubMed1993

Template activating factor I, a novel host factor required to stimulate the adenovirus core DNA replication.

The adenovirus (Ad) genome in virion exists in the form of the Ad core, which is a complex of Ad DNA and viral basic proteins. The Ad core supported only initiation and limited elongation in DNA replication in a cell-free system which was developed for DNA replication of naked Ad DNA. We found that addition of a cytoplasmic fraction from uninfected HeLa cells on the top of the system stimulated Ad core DNA replication, although it had no effect on DNA replication of naked Ad DNA. The factor stimulating Ad core DNA replication, designated as template activating factor I (TAF-I), was purified by successive steps of ammonium sulfate precipitation, column chromatographies on phosphocellulose and Q-Sepharose, and glycerol density gradient centrifugation. SDS-polyacrylamide gel electrophoresis of the purified fraction revealed the presence of proteins with molecular masses of 41 and 39 kDa. TAF-I stimulated both initiation and elongation in Ad core DNA replication. Judging from its behavior in purification steps, TAF-I could be acidic. These findings suggest that TAF-I stimulates Ad core DNA replication by interaction with viral basic core proteins.

Adenoviruses, Human↗
PubMed1993

Phosphorylation of NF-I in vitro by cdc2 kinase.

Nuclear factor I (NF-I) was purified to near homogeneity from Ehrlich ascites tumor cells. Mouse NF-I consisted of two peptides with relative molecular masses of 53 and 55 kDa and bound to the authentic NF-I site of the adenovirus DNA with no significant affinity with the CCAAT box. The purified protein was efficiently phosphorylated in a reaction containing immunoprecipitates with an anti-cdc2 kinase antibody. This phosphorylation was abolished when a synthetic peptide containing the consensus phosphorylation site by cdc2 kinase was added in excess to the reaction. These findings indicate that mouse NF-I is phosphorylated in vitro by the cdc2 protein kinase.

Animals↗
PubMed1993

Structure of the gene encoding the mouse 47-kDa heat-shock protein (HSP47).

HSP47, a 47-kDa heat-shock protein (HSP), is a member of a group of HSPs with the unique characteristics of collagen binding as well as transformation sensitivity. The protein belongs to the serpin (serine protease inhibitor) superfamily as determined from its amino acid sequence homology. We have isolated and characterized the mouse HSP47 including about 1 kb of the 5'-flanking region. This gene spans about 7.8 kb, consisting of six exons separated by five introns. This exon-intron structure is different from other serpin family proteins. Southern blot analysis revealed the existence of a single copy of HSP47. The promoter region contains a TATA box, four Sp1-binding sites and one AP-1-binding site. A complete heat-shock element (HSE) was found between nucleotides (nt) -61 and -79. Furthermore, the heat inducibility was reproduced by transfecting mouse BALB/3T3 cells with a plasmid carrying cat under the control of the HSE-containing fragment (nt -197 and +38) of HSP47. Computer analysis of the promoter region did not show marked homology to other vertebrate promoters.

3T3 Cells↗
PubMed1993

Microglial conditioned medium promotes survival and development of cultured mesencephalic neurons from embryonic rat brain.

We previously reported that microglial conditioned medium (Mic-CM) has a neurotrophic effect on cultured rat neocortical neurons [Nakajima et al. (1989): Biomed Res 10:411-423]. In order to investigate the interaction between microglia and neurons in more detail, we determined the effects of Mic-CM on the primary cultured mesencephalic neurons from 16-day embryonic rats. The addition of Mic-CM to the culture medium significantly enhanced the survivability of neurons and promoted neurite extension in a low cell-density culture condition. In a high cell-density culture condition, Mic-CM markedly increased dopamine uptake, which was quantified by assessing the specific [3H]dopamine uptake, and also increased the dopamine content of cultured cells. Furthermore, the number of mesencephalic dopaminergic neurons, which was determined by quantitative analysis of tyrosine hydroxylase (TH)-immunoreactive cells, increased significantly in the presence of Mic-CM. These results suggest that Mic-CM enhances survival or maturation of TH-positive neurons present in cultures of the embryonic mesencephalon and that these neurotrophic effects may be due to a diffusible factor(s) from microglia.

Animals↗
PubMed1993

Modulation of the phosphorylation of glucose-regulated protein, GRP78, by transformation and inhibition of glycosylation.

The phosphorylation of glucose-regulated protein, GRP78, is thought to be involved in the regulation of the binding function of GRP78 to immunoglobulin heavy chains. The phosphorylation of GRP78 proceeded faster in transformed cells than in normal cells, whereas the levels of GRP78 synthesis and accumulation were similar in both cells. Treatment of the cells with tunicamycin caused a rapid decrease in GRP78 phosphorylation within 2 to 4 h in both cell types prior to GRP78 induction. Following a longer period of tunicamycin treatment, GRP78 phosphorylation recovered gradually in parallel with the accumulation of newly synthesized GRP78. The half-life of GRP78 was over 24 h and similar in both normal and transformed cells either with or without tunicamycin treatment. In contrast, the half-life of phosphate groups incorporated into GRP78 was about 120 min in both types of cells in the absence of tunicamycin treatment. When the cells were treated with tunicamycin, the half-life of the phosphate groups was shortened (-30 min) only in transformed cells, while it remained at untreated control levels in normal cells. These results suggest that GRP78 phosphorylation is important in functional regulation, and that the cells may carry out particular requirements such as increasing or decreasing secretory proteins by modulating GRP78 phosphorylation rather than GRP78 synthesis.

3T3 Cells↗
PubMed1993

A cell-type-specific transcription enhancer of type 16 human papillomavirus (HPV 16)-P97 promoter is defined with HPV-associated cellular events in human epithelial cell lines.

Expression of the early genes of human papillomavirus type 16 (HPV16) is known to be highly restricted to epithelial cells. This report describes the molecular basis of HPV16 epitheliotropism at the transcriptional level. A series of 5'-end deletion mutants of the long control region (LCR) located upstream of the HPV16 early genes were tested in a transient expression assay using various human epithelial and fibroblastic cell lines. The specific region termed the cell-type-dependent regulatory element (CTRE) was found to function as an enhancer in some of HPV-associated human epithelial cell lines, but not at all in HPV-free human epithelial cell lines. No LCR-associated enhancer activity was detectable in fibroblastic cell lines. The CTRE was mapped at a distinct region upstream from the previously proposed proximal keratinocyte dependent enhancer (KD). The CTRE augmented transcription initiated from the autologous P97 promoter as well as from a heterologous promoter in a orientation-independent manner. Within the CTRE, there are three copies of the consensus nuclear factor-1 (NF1) binding site. Using CTRE containing mutations in each of the NF1-sites, it was demonstrated that all of these NF1-sites were necessary for a full enhancer activity in the HPV-associated human epithelial cell line. This suggests that the CTRE plays a critical role in the cell-type specific expression of HPV16-early gene at the level of transcriptional regulation.

Animals↗