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Biomedical subjects

K Nishimura

Publications and source records attributed to K Nishimura.

At least 289 records · Page 16Linked to original sources
PubMed1998

Retinoblastoma, a tumor suppressor, is a coactivator for the androgen receptor in human prostate cancer DU145 cells.

The retinoblastoma protein may function as a tumor suppressor by controlling the progression of the normal cell cycle. Inactivation of Rb has been regarded as an important event in prostate carcinogenesis. However, the detailed mechanism of how Rb is linked to androgen-androgen receptor (A-AR), the major factor in promotion of prostate tumor growth, remains unclear. Using GST-Rb pull down assay and mammalian two-hybrid system, we report here that Rb can bind specifically to AR in an androgen-independent manner. Transient transfection assay demonstrates that cotransfection of AR and Rb can further induce AR transcriptional activity 4-fold in the presence of 1 nM dihydrotestosterone in DU145 cells. Interestingly, cotransfection of Rb and ARA70, the first identified AR coactivator, with AR can additively induce AR transcriptional activity 13-fold (from 5-fold to 64-fold). In conclusion, our discovery that Rb can function as a coactivator to induce AR transcriptional activity in prostate cells may represent the first data to link a negative growth regulatory protein function in a positive manner, by inducing the transcriptional activity of AR.

Cell Cycle↗
PubMed1998

Measurement of early pregnancy factor activity for monitoring the viability of the equine embryo.

The viability of embryos before flushing from donor mares (n = 5) and after transfer to recipient mares (n = 7) was monitored in mare serum by detecting early pregnancy factor (EPF) using the rosette inhibition test (RIT). The EPF activity was measured in donor mares before and after natural mating at natural estrus; after ovulation on Days 2, 5 and 8; and after embryo flushing (Day 8) on Days 8, 9, 10 and 13 after ovulation. The collected embryos were transferred immediately after flushing. The EPF activity in recipient mares were measured on the day of transfer and after embryo transfer on Days 1, 2, 3 and 5. Pregnancy was confirmed on Day 12 to 14 after embryo transfer. The mean EPF activity of donor mares was increased to the pregnant level (> an RI titer score of 10) on Day 2 after ovulation. Two days after flushing the embryos, the EPF activity of donor mares had decreased to the nonpregnant level. Among the 7 recipient mares, 3 mares were diagnosed pregnant on Day 12 after embryo transfer with ultrasound. The EPF activity of the pregnant recipient mares was increased above the minimum level observed in pregnant mares on Days 2 to 3 after transfer. However, among the nonpregnant recipient mares after embryo transfer, the EPF activity of 3 mares remained at the pregnant level only 2 to 3 d and then declined to the nonpregnant level. In one recipient mare, EPF activity did not reach the pregnant level throughout the sample collection. The results of this study indicated that equine EPF can be detected in serum of pregnant mares as early as Day 2 after ovulation. From our observation, we conclude that the measurement of EPF activity is useful for monitoring the in vivo viability of equine embryos and early detection of embryonic death.

Animals↗
PubMed1998

Percutaneous reinsertion of the nucleus pulposus. An experimental study.

STUDY DESIGN: An analysis of the histologic changes in intervertebral discs after percutaneous reinsertion of the nucleus pulposus in rats. OBJECTIVE: To devise a way to delay further disc degeneration resulting from spinal deformity and the adverse effects of various treatments. SUMMARY OF BACKGROUND DATA: The role of the nucleus pulposus of the intervertebral disc described by many investigators has not been fully clarified. METHODS: Disc herniation was induced in the tails of 112 Wistar rats, using a fixation device between the 5th and 8th coccygeal vertebrae. After percutaneous nucleotomy at coccygeal vertebrae 5-6 and 6-7, fresh nucleus pulposus, cryopreserved nucleus pulposus, or an artificial substitute was inserted into the intervertebral disc at coccygeal vertebrae 5-6. Two, 4, or 8 weeks after reinsertion, disc sections from each coccygeal level were studied histopathologically. RESULTS: In the groups with reinsertion of fresh or cryopreserved nucleus pulposus, degenerative changes of the disc with the reinserted nucleus at coccygeal vertebrae 5-6 were milder than those of the disc without reinsertion at coccygeal vertebrae 6-7. However, no apparent benefit from reinsertion was observed in the group with artificial substitutes. CONCLUSIONS: Early reinsertion of the nucleus pulposus (fresh or cryopreserved) delays degeneration of such disc materials as the anulus fibrosus, endplate, and remaining nucleus pulposus.

Animals↗
PubMed1998

NC-1900, an active fragment analog of arginine vasopressin, improves learning and memory deficits induced by beta-amyloid protein in rats.

We have reported that the continuous infusion of beta-amyloid protein-(1-40) into the rat cerebral ventricle produces learning and memory deficits accompanied by dysfunction in the cholinergic and dopaminergic systems. L-Pyroglutamyl-L-asparaginyl-L-seryl-L-prolyl-L-arginylglycinamide (NC-1900), an active fragment analog of arginine vasopressin in the rat brain, is a stable peptide with a five-fold longer half-life than that of arginine vasopressin-(4-9). In the present study, we examined the effects of NC-1900 on learning and memory deficits in beta-amyloid protein-(1-40)-infused rats. The rats were injected subcutaneously with NC-1900 (0.1 and 1 ng kg(-1)) once a day throughout the period of behavioral examination. In the beta-amyloid protein-infused rats, learning and memory in water maze and passive avoidance tasks were impaired compared with these in the control rats. NC-1900 prevented the learning and memory deficits in beta-amyloid protein-infused rats. Moreover, NC-1900 tended to increase the choline acetyltransferase activity in the frontal cortex of the beta-amyloid protein-infused rats. These results suggested that NC-1900 could be useful for the treatment of patients with Alzheimer's disease.

Amyloid beta-Peptides↗
PubMed1998

Structure and activity of mouse S-adenosylmethionine decarboxylase gene promoters and properties of the encoded proteins.

The promoter regions of two S-adenosylmethionine decarboxylase genes (AMD genes) were isolated from a mouse genomic library. One promoter was that of the bona fide mouse AMD gene (AMD1) whereas the other was that of the intronless AMD gene (AMD2). There was no sequence identity between the two promoters. The sequence of the AMD1 promoter was highly homologous to the human AMD1 and rat Amd1B promoters. After transient transfection in various cell lines, the AMD1 promoter was one to two orders of magnitude stronger than the AMD2 promoter. Similar results were obtained by using stably transfected mouse FM3A cells. In S-adenosylmethionine decarboxylase (AdoMetDC)-overproducing SAM-1 cells, the AMD1 gene was amplified over 5-fold. AdoMetDC encoded by the intronless AMD2 gene had two amino acid replacements (Met to Ile at codon 70 and Ala to Val at codon 139), compared with the protein encoded by the AMD1 gene, and exhibited decreased catalytic activity (<50%) and decreased processing activity when expressed in AdoMetDC-deficient Escherichia coli cells. When Ile-70 of the protein encoded by AMD2 was converted into Met, both the catalytic and processing activities recovered markedly, indicating that Met-70 adjacent to the proenzyme-processing site is important for both activities. The third AMD locus (AMD3) in FM3A cells contains a pseudogene, in which deletion of two bases generates a premature termination codon at position 57. Since the AMD2 promoter had only 1-10% of the strength of the bona fide AMD1 gene and AMD2 protein possessed lower specific activity, the relative contribution of the AMD2-encoded enzyme to total AdoMetDC activity is small. Thus AdoMetDC activity in murine cells is thought to be due mainly to the product of the AMD1 gene.

Adenosylmethionine Decarboxylase↗
PubMed1998

Comparative study on recombinant chloroplastic and cytosolic ascorbate peroxidase isozymes of spinach.

The spinach stromal, thylakoid-bound, and cytosolic ascorbate peroxidase isozymes (EC 1.11.1.11) were overexpressed in Escherichia coli, and their enzymatic properties were compared with the respective native isozymes. The purification of the recombinant stromal and cytosolic ascorbate peroxidases using the conventional column chromatography yielded 0.73 and 2.2 mg of protein/liter of bacteria culture with enzyme activities of 800 and 486 micromol min-1 mg protein-1, respectively. In every respect, the recombinant stromal, thylakoid-bound, and cytosolic ascorbate peroxidase isozymes exhibited identical enzymatic properties with each native isozyme. Specifically, the recombinant stromal and thylakoid-bound ascorbate peroxidase isozymes showed high utilization of ascorbate as an electron donor and had a very short lifetime in ascorbate-depleted medium. Polyclonal antibodies raised against both purified recombinant stromal and cytosolic ascorbate peroxidase isozymes were prepared. Both antibodies showed a cross-reaction with the recombinant and native ascorbate peroxidase isozymes.

Amino Acid Sequence↗
PubMed1998

Characterization of GRK2-catalyzed phosphorylation of the human substance P receptor in Sf9 membranes.

G protein-coupled receptor kinases (GRKs) phosphorylate agonist-occupied G protein-coupled receptors (GPCRs), resulting in GPCR desensitization. GRK2 is one of the better studied of the six known GRKs and phosphorylates several GPCRs. In a previous study, we documented that GRK2 and GRK3 phosphorylate purified and reconstituted rat substance P receptor (rSPR) [Kwatra et al. (1993) J. Biol. Chem. 268, 9161-9164]. Here, we characterize in detail GRK2-catalyzed phosphorylation of human SPR (hSPR) in intact membranes. GRK2 phosphorylates hSPR in urea-washed Sf9 membranes in an agonist-dependent manner with a stoichiometry of 19 +/- 1 mol of phosphate/mol of receptor, which increases slightly (1.3-fold increase) in the presence of G beta gamma. Kinetic analyses indicate that receptor phosphorylation occurs with a Km of 6.3 +/- 0.4 nM and a Vmax of 1.8 +/- 0.1 nmol/min/mg; these kinetic parameters are only slightly affected by G beta gamma [Km = 3.6 +/- 1.0 nM and Vmax = 2.2 +/- 0.2 nmol/min/mg]. The lack of a strong stimulatory effect of G beta gamma on GRK2-catalyzed phosphorylation of hSPR is surprising since G beta gamma potently stimulates GRK2-catalyzed phosphorylation of beta 2-adrenergic receptor and rhodopsin. Involvement of G beta gamma endogenously present in membranes is ruled out as a source of high levels of hSPR phosphorylation, since receptor phosphorylation was not affected by guanine nucleotides that suppress or enhance the release of endogenous G beta gamma. The present study determines, for the first time, the kinetics of phosphorylation of a receptor substrate of GRK2 in intact membranes. Further, our results identify hSPR as a unique substrate of GRK2 whose phosphorylation is strong even in the absence of G beta gamma.

Amino Acid Sequence↗
PubMed1998

[A case of progressive saccular aneurysm caused by localized dissection of descending aorta].

A fifty-three-year-old man was admitted because of chest pain. CT scan showed the localized dissection of the descending aorta which was partially thrombosed. The patient was followed by controlling of essential hypertension. He, however, complained of the second attack of chest pain after a year and 5 months. CT scan showed the increased dilatation of the false lumen as compared to that of previous examination. MR angiogram showed a saccular aneurysm localized in the middle portion of the descending aorta. An operation was performed through posterolateral thoracotomy in the 4th intercostal space with the aid of normothermic femoro-femoral bypass circulation. The aneurysm was located at the level of 5th thoracic vertebra with the size of 70 mm in length and 45 mm in diameter. Entry was observed in the posterior wall of the aorta, and the terminal end of the false lumen was occluded with the organized thrombus. The aneurysm was successfully replaced with a prosthetic graft. To the extent of our knowledge, only limited surgical cases of saccular aneurysm caused by localized dissection of the middle portion of the descending aorta have been reported.

Aortic Dissection↗
PubMed1998

[A total correction for tetralogy of Fallot without the use of homologous blood].

In 22 consecutive patients with tetralogy of Fallot (TF), a total correction was attempted without the use of a homologous blood transfusion from September 1995 to March 1997. The 22 patients were divided into two groups according to their surgical procedures; namely, either a simple correction (group I: n = 14) or a complex correction including the relief of peripheral pulmonary stenosis and/or the division of a previous systemic-pulmonary shunt (group II: n = 8). In 77% of all patients, surgery was performed without a homologous blood transfusion. No differences were found in the non-transfusion rate and the hematocrit (Ht) values between the two groups and, as a result, we thus confirm that this additional procedure is not a risk factor for surgery without a homologous blood transfusion. According to the correlation of the red blood cell volume before and after surgery, the preoperative Ht value corresponding to the postoperative Ht of 30% could be accurately predicted. The calculated Ht values were 41.0% in the patient weighing 15 kg, 42.5% in those weighing 10 kg, and 46.9% in those weighing 5 kg. These data suggest that a surgical correction without a homologous blood transfusion can therefore be safely performed in almost all patients with TF.

Blood Transfusion, Autologous↗
PubMed1998

Acute hepatic failure due to hepatosplenic B-cell non-Hodgkin's lymphoma in a patient infected with hepatitis C virus.

We report a 75-year-old Japanese man infected with hepatitis C virus (HCV) who died of acute hepatic failure due to the hepatic infiltration of B-cell non-Hodgkin's lymphoma (NHL) cells. He suddenly developed jaundice, fatigue, fever, and hepatosplenomegaly during the course of chronic infection with HCV. Postmortem liver necropsy revealed extensive infiltration of lymphoma cells into the liver. Although the association between HCV infection and NHL has recently become a matter of concern, we believe this to be the first reported case of acute hepatic failure caused by hepatic involvement of non-Hodgkin's lymphoma in an HCV-infected patient.

Aged↗
PubMed1998

Changes in macrophage colony-stimulating factor concentration in serum and follicular fluid in in-vitro fertilization and embryo transfer cycles.

OBJECTIVE: To evaluate the changes of macrophage colony-stimulating factor concentration in serum and compare macrophage colony-stimulating factor concentration in follicular fluid (FF) through IVF-ET cycles. DESIGN: Sera and the matched FFs were collected serially through the IVF-ET cycles and analyzed retrospectively with respect to macrophage colony-stimulating factor concentration. SETTING: Department of Obstetrics and Gynecology of Kumamoto University Hospital. PATIENT(S): Ninety-four women underwent 129 cycles of ovulation induction by using GnRH agonist (GnRHa)-hMG-hCG for IVF-ET program. INTERVENTION(S): Serum and FF macrophage colony-stimulating factor concentrations were measured by ELISA. MAIN OUTCOME MEASURE(S): Concentrations of macrophage colony-stimulating factor in serum and FF. RESULT(S): Serum macrophage colony-stimulating factor concentration was gradually increased throughout ovarian stimulation, and reached a peak from the day of oocyte retrieval to 2 days after oocyte retrieval, whereas no significant change in macrophage colony-stimulating factor was observed in cases of poor ovarian response to hMG. The macrophage colony-stimulating factor concentration in follicles was significantly higher than that in sera on the day of oocyte retrieval, and the concentrations in follicles from which oocyte could be retrieved were significantly higher than those from which oocyte could not be retrieved. CONCLUSION(S): These results suggest that gonadotropins lead to an increase in ovarian macrophage colony-stimulating factor production, and that this macrophage colony-stimulating factor production in response to hMG administration is lost in poor ovarian responders. Thus, macrophage colony-stimulating factor may play an important role in the process of follicular maturation and ovulation as an intraovarian regulator.

Adult↗
PubMed1998

Susceptibility to idiopathic azoospermia in Japanese men is linked to HLA class I antigen.

PURPOSE: Approximately 15 to 20% of infertile men have azoospermia. In the Y chromosome a deletion, termed the azoospermic factor, has been found in some cases of idiopathic azoospermia. We investigate the relationship of factors in autosomal chromosomes (HLA class I antigens) to spermatogenesis failure in idiopathic azoospermia. MATERIALS AND METHODS: We evaluated 65 infertile Japanese men with idiopathic azoospermia. The frequency of the HLA allele reported in 1,216 healthy Japanese men was used as a control. HLA class I typing was performed by the National Institutes of Health standard serological method or polymerase chain reaction-sequence specific primer analysis. Allele frequencies were calculated. We determined statistical significance in the frequency of each allele in patients and controls using the chi-square test. The relationship of HLA antigens to idiopathic azoospermia was expressed as relative risk. RESULTS: In Japanese men with idiopathic azoospermia the frequency of HLA-A33, B13 and B44 was significantly increased compared with controls. The relative risk of HLA-B44 was 8.4, an extremely high value compared with that of other diseases and HLA antigens. CONCLUSIONS: We suggest that HLA class I antigens are important genetic markers that represent a risk factor for idiopathic azoospermia.

Alleles↗
PubMed1998

A comparison of different methods of spirometric measurement selection.

The American Thoracic Society (ATS) and the European Respiratory Society (ERS) recommend that the largest forced vital capacity (FVC) and the largest forced expiratory volume in 1 s (FEV1) should be recorded from at least three acceptable curves independently which curve they came from. Although these recommendations have been used for decades, there is still some controversy over their validity. The purpose of this study was to determine how the intersession variability of reported FVC and FEV1 values is influenced by different methods of selection in clinical practice. The study population consisted of 283 patients with obstructive airway diseases. Spirometry was performed until three acceptable forced expiratory curves were obtained in the standing position. A second set of spirometric measurements was obtained approximately 30 min after the first set of measurements. The following sampling methods were compared: method A, the largest FVC and the largest FEV1 among all three acceptable curves (ATS-ERS recommendation); method B, the FVC and the FEV1 from the single curve that yielded the largest sum of FVC plus FEV1 (best test); method C, the average of all three acceptable curves; method D, the average of the largest two FVCs and FEV1s among all of the three acceptable curves. FVC and FEV1 determined by method B gave almost identical values to those obtained by method A in most cases. However, method A was least variable for FEV1. In addition, the differences in FEV1 values between these two methods were large in some of patients with chronic obstructive pulmonary disease. The other selection criteria compared in this study offer no clear-cut advantages over method A. The ATS ERS recommended method appeared to be slightly more reproducible than the other selection criteria, including the 'best test' method, and should therefore be the preferred method of choice.

Asthma↗
PubMed1998

Comparison of four types of portable peak flow meters (Mini-Wright, Assess, Pulmo-graph and Wright Pocket meters).

Ambulatory peak flow monitoring plays an important role in the diagnosis and management of patients with bronchial asthma. Today several kinds of portable peak flow meters (PFMs) are available for this purpose and sometimes comparisons between the readings of different kinds of PFMs are necessary in clinical setting. We compared four types of PFMs in patients with various respiratory diseases. The study population consisted of 294 patients with asthma, chronic obstructive pulmonary disease, diffuse panbronchiolitis and other respiratory systems, and 15 healthy volunteers. Initially, subjects underwent a spirometry until at least three acceptable forced expiratory curves were obtained. Thereafter each subject blew into a Mini-Wright meter, Assess meter, Pulmo-graph meter and Wright Pocket meter, three times in a random order, with an interval of 4 min. The highest value of three blows was recorded in each PFM measurement. Finally, a second set of spirometric measurements were obtained. Spirometric peak flow rates (PEFRs) were obtained from the best single test which gave the largest sum of forced vital capacity and forced expiratory volume in 1 s (FEV1). In cases when FEV1 in the first spirometry examination was less than 11 or the readings of the PFM were less than 3501 min-1, low-range PFMs were used. The second spirometric PEFR was used as a standard against which the reading of the PFM was compared. The correlation coefficients between the readings of each PFM and spirometric PEFR did not differ significantly from each other. The limits of agreement between each PFM were very wide. In both low- and standard-range PFM, the Assess meter had a significantly greater absolute difference from the spirometric PEFR than other PFMs. In the standard range, the Wright Pocket meter also had a greater difference than the Pulmo-graph meter. The standard-range Assess meter tended to lose its strength of correlation with the spirometric measurement at higher flow rates as did the low-range Pulmo-graph and Mini-Wright meters at the lower and higher flow rates, respectively. All four types of standard-range PFMs gave similarly valid values when spirometric PEFR was used as a reference. However, the limit of agreement between each PFM is so wide that we do not recommend the use of the readings of each meter interchangeably.

Asthma↗
PubMed1998

Presence of DNase gamma-like endonuclease in nuclei of neuronal differentiated PC12 cells.

DNase gamma, which cleaves chromosomal DNA into nucleosomal units (DNA ladder formation), has been suggested to be the critical component of apoptotic machinery. Using rat pheochromocytoma PC12 cells, which are differentiated to sympathetic neurons by nerve growth factor (NGF), we investigated whether DNase gamma-like enzyme is present in neuronal cells and is involved in neuronal cell death. The nuclear auto-digestion assay for DNase catalyzing internucleosomal DNA cleavage revealed that nuclei from neuronal differentiated PC12 cells contain acidic and neutral endonucleases, while nuclei from undifferentiated PC12 cells have only acidic endonuclease. The DNA ladder formation observed in isolated nuclei from neuronal differentiated PC12 cells at neutral pH requires both Ca(2+) and Mg(2+), and is sensitive to Zn(2+). The molecular mass of the neutral endonuclease present in neuronal differentiated PC12 cell nuclei is 32000 as determined by activity gel analysis (zymography). The properties of the neuronal endonuclease present in neuronal differentiated PC12 cell nuclei were similar to those of purified DNase gamma from rat thymocytes and splenocytes. Interestingly, in neuronal differentiated PC12 cells, internucleosomal DNA fragmentation is observed following NGF deprivation, whereas undifferentiated PC12 cells fail to exhibit DNA ladder formation during cell death by serum starvation. These results suggest that the DNase gamma-like endonuclease present in neuronal differentiated PC12 cell nuclei is involved in internucleosomal DNA fragmentation during apoptosis, induced by NGF deprivation.

Journal Article↗
PubMed1998

Intradural extra-arachnoid schwannoma of the upper cervical spine.

A very rare case of intradural extra-arachnoid schwannoma involving the upper cervical spine is described. The tumour most likely originated from the extra-subarachnoid angle region, with its unusual pattern of expansion within the spinal canal resulting from such characteristics of the upper cervical region as a relatively wide spinal canal, an extensive ventral subarachnoid space, and membranous ventromedian and lateral anchoring structures which influenced the direction of tumour enlargement.

Cervical Vertebrae↗
PubMed1998

Sphingosylphosphorylcholine stimulates proliferation and upregulates cell surface-associated plasminogen activator activity in cultured human keratinocytes.

Of the various sphingolipid metabolites, including sphingosine, sphingosylphosphorylcholine (SPC), dimethylsphingosine, sphingosine-1-phosphate, N-acetylsphingosine, and skin-specific ceramides, only SPC accelerated cutaneous wound healing in full-thickness excision wounds in genetically healing-impaired diabetic (db/db) mice. A histologic examination revealed that SPC promoted not only granulation tissue formation, but also the re-epithelization of epidermal keratinocytes. As the direct effects of SPC on keratinocytes are completely unknown, we investigated the effects of SPC on normal cultured human keratinocytes. SPC concentration-dependently enhanced DNA synthesis in keratinocytes, with an increase in intracellular calcium concentrations due to the release of calcium ions from intracellular stores. SPC upregulated cell surface plasminogen activity, and at the same time increased the cell surface expression of urokinase-type plasminogen activator (uPA) and urokinase-type plasminogen activator-receptor (uPA-R) in keratinocytes. Furthermore, SPC promoted the in vitro wound repair of cultured keratinocytes, which was partially blocked by an anti-uPA monoclonal antibody. Our results suggest that one of the mechanisms responsible for the SPC-mediated promotion of cutaneous wound healing seems to be an enhancement of re-epithelization caused by the direct stimulation of the proliferation of keratinocytes, and an activation of the uPA/uPA-R system, which enhances the migration of keratinocytes.

Animals↗