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Biomedical subjects

K Nakashima

Publications and source records attributed to K Nakashima.

At least 343 records · Page 19Linked to original sources
PubMed1996

Structure and characterization of rat cyclin D3 promoter.

To investigate the transcription initiation mechanism of the gene encoding cyclin D3, one of the major G1 cyclins to promote the G1/S transition, we cloned the 5' portion of rat cyclin D3 gene and analyzed the promoter region. The major transcription start point of the gene was identified by the primer extension experiment to be 207 bp upstream from the ATG start codon and its promoter region was found to have no canonical TATA box. The DNA mobility shift assay and DNase I footprinting analysis using nuclear extracts from Nb2 cells stimulated by prolactin (PRL) have clearly revealed that the promoter possesses two binding sites for the PRL-induced transcription factors. One is located between -1 and -59 bp (Region I) and the other between -328 and -380 bp (Region II). The induction of transcription factors by PRL was blocked by simultaneous addition of cycloheximide, suggesting that protein synthesis was necessary for the release of these PRL-responsive transcription factors. Region I contained putative binding elements for ATF/CREB, SP1 and AP2, and Region II contained elements for a MCBF/MGF and a novel factor. These results suggest that the cyclin D3 gene is a TATA-less gene whose transcription is regulated by multiple mitogen-inducible transcription factors including an unknown factor.

Amino Acid Sequence↗
PubMed1996

Accelerated evolution of crotalinae snake venom gland serine proteases.

Eight cDNAs encoding serine proteases isolated from Trimeresurus flavoviridis (habu snake) and T. gramineus (green habu snake) venom gland cDNA libraries showed that nonsynonymous nucleotide substitutions have accumulated in the mature protein-coding regions to cause amino acid changes. Southern blot analysis of T. flavoviridis genomic DNAs using two proper probes indicated that venom gland serine protease genes form a multigene family in the genome. These observations suggest that venom gland serine proteases have diversified their amino acid sequences in an accelerating manner. Since a similar feature has been previously discovered in crotalinae snake venom gland phospholipase A2 (PLA2) isozyme genes, accelerated evolution appears to be universal in plural isozyme families of crotalinae snake venom gland.

Amino Acid Sequence↗
PubMed1996

Ligation of lateral carotid artery attenuates disturbance of brain function caused by subsequent cerebral ischemia in rabbits.

The effects of right carotid artery ligation on the subsequent cerebral ischemia, induced by iron particle injection, in rabbits, were evaluated by recording somatosensory evoked potentials (SEPs) and cerebral blood flow (CBF) using laser Doppler flowmetry. Iron particle injection decreased CBF over 120 min and delayed SEP onset latency in rabbits with no previous carotid artery ligation (control group). In rabbits with a carotid ligation 3 days before, iron particle injection induced the decrease of CBF, as in the control group, but did not prolong the latency of SEP. Injection of iron particles induced only a transient decrease of CBF (less than 10 min) followed by an abrupt recovery, and no prolongation of SEP latency was observed in rabbits with a carotid ligation 6 days before. These results suggest that carotid artery ligation induces a beneficial effect on cerebral function during the subsequent ischemia, which is independent on the CBF changes.

Animals↗
PubMed1996

Accelerated evolution of Trimeresurus okinavensis venom gland phospholipase A2 isozyme-encoding genes.

Three Trimeresurus okinavensis (To; himehabu snake, Crotalinae) venom gland phospholipase A2 (PLA2) isozymeencoding genes, gPLA2-o1, gPLA2-o2 and gPLA2-o3, were isolated from its genomic DNA library. The nucleotide (nt) sequence analysis revealed that two of the three genes (gPLA2-o2 and gPLA2-o3) occasionally have been converted to inactivated genes by introduction of one base insertion or substitution. It was confirmed from Southern blot analysis that the To haploid genome contains only three venom gland PLA2 isozyme genes herein isolated. Comparison of these genes showed that nonsynonymous nt substitutions have occurred more frequently than synonymous nt substitutions in the protein-coding regions, except for the signal-peptide coding domain, implying that To venom gland PLA2 isozyme genes have evolved via accelerated evolution. Such an evolutionary feature of To venom gland PLA2 isozyme genes proves the general universality of accelerated evolution previously drawn for venom gland PLA2 isozyme genes of other crotalinae snakes. The variability in the mature protein-coding regions of three To venom gland PLA2 isozyme genes appears to have been brought about by natural selection for point mutations.

Amino Acid Sequence↗
PubMed1996

Chimeras of yeast and chicken calmodulin demonstrate differences in activation mechanisms of target enzymes.

Various chimeric proteins were constructed from yeast (Saccharomyces cerevisiae) and chicken calmodulin (CaM), and regions essential for target activation and responsible for the specific features of the yeast CaM were identified. The chimeric CaMs were designed so that each Ca2+ binding site of the yeast CaM was replaced in series from the C-terminus. Resulting CaM proteins showed Ca2+ binding properties inherent to the original Ca2+ binding site. Cooperative Ca2+ binding and a suitable rearrangement of the two EF-hand sites in each half-molecular domain were shown to be important for high-affinity interaction with CaM-dependent cyclic nucleotide phosphodiesterase (PDE). Residues in chicken CaM sequences 129-148 and 88-128, respectively, were required for low values of Kact (the concentration of CaM required for the half-maximal activation) in the activation of PDE and myosin light chain kinase (skMLCK and smMLCK). The difference in the structural requirements indicated different manners of the interaction. While PDE was activated to similar levels by different chimeras, the maximum activity (Vmax) given by chicken CaMs was not achieved by any chimeric CaMs in MLCKs. Residues in chicken CaM sequences 1-50 and 88-129, in addition to Ca2+ binding to the fourth site, were important for high values of Vmax of skMLCK. On the other hand, Met51 and residues in chicken CaM sequence 88-129 were critical for the high Vmax of smMLCK. These residues may work to form the active structure of the catalytic site of each MLCK, while simple binding of CaM seems sufficient to expose the active site of PDE.

Amino Acid Sequence↗
PubMed1996

Sensitive flow-injection method with peroxyoxalate chemiluminescence detection combined with preparative high-performance liquid chromatography for determination of choline-containing phospholipids in human serum.

A sensitive and rapid flow-injection analysis (FIA) of total choline-containing phospholipids (PLs) and a selective FIA method for the class assay of choline-containing PLs combined with preparative HPLC were described. The FIA method is based on peroxyoxalate chemiluminescence (PO-CL) detection of hydrogen peroxide enzymatically formed from choline-containing PL. The linear standard curves were obtained up to 1 nmol/20-microliters injection (r > 0.999) with the detection limits of 1.3-1.6 pmol at a signal-to-noise ratio of 2. The total amounts of choline-containing PLs in human serum were ranged from 1.63 to 3.19 mg/ml. The HPLC separation of choline-containing PLs was achieved with an aminopropyl-modified silica gel column using a mixture of acetonitrile-methanol-10 mM ammonium phosphate buffer pH 5.8 as eluent. The eluate corresponding to each choline-containing PL was collected, evaporated, dissolved in 0.1% Triton X-100 aqueous solution, and then injected into FIA system. The FIA method combined with preparative HPLC was applied to the assay of human serum.

Choline↗
PubMed1996

Prolactin induces switching of T-cell receptor gene expression from alpha to gamma in rat Nb2 pre-T lymphoma cells(1)

Prolactin (PRL) is considered to be an immunomodulator. This study was conducted to analyze the actions of PRL on the gene expressions for T-cell receptor (TCR) chains in a fat pre-T lymphoma cell line, Nb2. PRL remarkably stimulated the gene expression for TCR gamma chain within 4 h and suppressed TCR alpha chain mRNA expression within 8 h in Nb2 cells. The expression of TCR beta mRNA in the cells was concomitantly, but to a less extent, repressed by the hormone treatment. These results suggest that PRL may participate in the regulation of mammalian T-cell differentiation and development.

Amino Acid Sequence↗
PubMed1996

Use of 3-(1,8-naphthalimido)propyl-modified silyl silica gel as a stationary phase for the high-performance liquid chromatographic separation of purine derivatives.

The use of a packing material, 3-(1,8-naphthalimido)propyl-modified silyl silica gel (NAIP), as a stationary phase for high-performance liquid chromatography, has been studied. NAIP behaved like a reversed-phase stationary phase with some pi-pi interaction. Purine derivatives, i.e., xanthine, hypoxanthine, uric acid, theobromine, theophylline and caffeine, were separated by a column packed with NAIP using an eluent of borate solution (pH 6.4)-MeOH (50:50, v/v). Of these, caffeine was selected as the target of the subsequent investigation and its determination was examined in commercially available medicinal drinks and pharmaceutical preparations. The average recoveries of caffeine were 98.0-107.4% for five drinks and 99.6-107.8% for five tablets and one powder. Subsequently, determination of caffeine and its metabolites in human plasma was examined. In twelve normal human plasma, caffeine levels ranged from 0.24 to 4.26 micrograms/ml. Time curves of plasma caffeine concentrations and those of its demethylated metabolite, 1,7-dimethylxanthine (1,7-DMX), after an oral ingestion of caffeine (200 mg) were measured by the proposed method and it was found that the maximum concentrations of caffeine and 1,7-DMX were obtained at 1-1.5 h and 3-6 h after ingestion, respectively.

1-Naphthylamine↗
PubMed1996

Stereoselective binding of carbenicillin epimers to human serum albumin.

Binding of carbenicillin (CBPC) epimers to human serum albumin (HSA) was found to be stereoselective. Epimer-epimer interaction was also observed in the binding to HSA. There were at least three binding sites on HSA for CBPC epimers, one of which (stereoselective site) was more in favor of S-CBPC than R-CBPC. At the stereoselective site, the binding constant of S-CBPC was approximately 4-fold greater than that of R-CBPC. The affinities to other binding sites (non-stereoselective sites) were similar between the epimers, and the affinity of S-CBPC of the non-stereoselective sites was much smaller than that for the stereoselective site. R-CBPC and S-CBPC appeared to displace each other at all the binding sites, i.e., the binding of the epimers was competitive at the non-stereoselective sites as well as at the stereoselective site. By using site marker ligands, it was revealed that CBPC epimers may bind to Site I (warfarin binding site), but not to Site II (diazepam binding site). A binding model with an assumption of competitive interactions at all the binding sites simulated the binding characteristics of CBPC epimers fairly well.

Binding Sites↗
PubMed1996

IL-1 beta and TNF-alpha produced by peripheral blood mononuclear cells before and during interferon therapy in patients with chronic hepatitis C.

We investigated the spontaneous and phytohemagglutinin-stimulated production of interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) by peripheral blood mononuclear cells in patients with chronic hepatitis C during treatment with interferon-alpha (IFN-alpha). Spontaneous productions of these were significantly higher in patients with chronic hepatitis C than in healthy subjects. For patients prescribed interferon, stimulated production of TNF-alpha was significantly higher in complete responders than in partial responders, but the differences were small between the other cytokine levels and outcome of IFN treatment. Spontaneous production of these cytokines was higher in patients with genotype III with complete response than in genotype III patients with a partial response, but this was not the case in patients with genotype II. There was a negative correlation between these cytokines and histological activity index. Spontaneous production of cytokines was decreased only in complete responders after the administration of interferon. These data suggest that the elevated production of cytokines in patients with chronic hepatitis C may be due to host response to the virus, and monitoring cytokines along with alanine aminotransferase and hepatitis C virus RNA during treatment may provide more precise information of the effectiveness of therapy.

Adult↗
PubMed1996

Prevalence of hepatitis C virus infection among female prostitutes in Fukuoka, Japan.

To assess the risk of sexual transmission of hepatitis C virus (HCV), we surveyed female prostitutes to determine the prevalence of antibody to HCV (anti-HCV) and HCV RNA. Anti-HCV was examined with a second generation anti-HCV test employing a passive hemagglutination assay. HCV RNA was detected by two-stage polymerase chain reaction with primers deduced from the 5'-noncoding region of the HCV genome. All studies were performed in Fukuoka, Japan, from 1989 through 1992 and all subjects were Japanese and had no history of intravenous drug abuse. The prevalence of anti-HCV was significantly higher in the prostitutes (10.1%; 61/604) than in the controls (female blood donors; 0.8%; 52/6632) (P < 0.001). HCV RNA was found in 73.2% of the anti-HCV-positive prostitutes. The prevalence of anti-HCV among prostitutes increased with the number of years spent in prostitution (P < 0.05). Prostitutes with a history of syphilis had a higher prevalence of anti-HCV than those with no history of syphilis, irrespective of the number of years in prostitution. In a longitudinal study of 244 prostitutes, 2 of the 218 initially seronegative subjects showed anti-HCV and HCV RNA over the study period of 3 years. These two persons had no history of percutaneous exposure. Sexual transmission of HCV presents a risk for female prostitutes.

Adolescent↗
PubMed1996

Immobilized 2-(4-hydrazinocarbonylphenyl)-4,5-diphenylimidazole as solid phase luminophore in peroxyoxalate chemiluminescence.

A new luminophore for application in peroxyoxalate chemiluminescence is presented. An analogue of the well-known chemiluminescence compound lophine, i.e. 2-(4-hydrazinocarbonylphenyl)-4,5-diphenylimidazole (HCPI), has been covalently immobilized to controlled pore glass and a porous methacrylate resin. By using this reagent in a solid phase detection reactor, sensitive determinations of hydrogen peroxide have been demonstrated. In homogeneous solution HCPI emits poorly as a result of 1,1'-oxalyldiimidazole excitation, but when immobilized its efficiency is almost comparable to highly efficient luminophores such as 3-aminofluoranthene. Linearity extends in the single stream flow system over several orders of magnitude with both materials. The limit of detection was 1 nmol/l (10 fmole injected), when using the porous methacrylate support.

Journal Article↗
PubMed1996

Secondary structure and Ca(2+)-binding property of the N-terminal half domain of calmodulin from yeast Saccharomyces cerevisiae as studied by NMR.

Using two- and three-dimensional NMR techniques, 1H and main-chain 15N resonances of the N-terminal half domain of yeast calmodulin (YCM0-N) in the presence of Mg2+ and Ca2+ (Mg(2+)-and Ca(2+)-forms) were assigned. The secondary structures of YCM0-N in both forms were determined. The NOESY and 15N-edited NOESY spectra of YCM0-N in each form indicate that there is a hydrophobic core and that two Ca(2+)-binding loops are connected by a short antiparallel beta-sheet. There are four helices (A, B, C, and D named from the N-terminus) for YCM0-N in the Mg(2+)-form. The B-helix is, however, not formed in the Ca(2+)-form. The Ca(2+)-binding of YCM0-N was monitored by (1H,15N)-HSQC at various Ca2+ concentrations. The observed spectral changes as a function of Ca(2+)-concentration can not readily be grouped into a small number of classes; each residue shows individual spectral change. There is no apparent relationship between the spectral change and the type or location of the amino acid concerned.

Amino Acid Sequence↗
PubMed1996

Effects of hypothermia, pentobarbital, and isoflurane on postdepolarization amino acid release during complete global cerebral ischemia.

BACKGROUND: Hypothermia and anesthetics may protect the brain during ischemia by blocking the release of excitatory amino acids. The effects of hypothermia (28 degrees C), pentobarbital, and isoflurane on postischemic excitatory amino acid concentrations were compared. METHODS: Rats were anesthetized with 0.8% halothane/50% N2O, vascular catheters were placed, and a glass microelectrode and microdialysis cannula were inserted into the cerebral cortex. Experimental groups were: (1) control, pericranial, t = 38 degrees C; (2) hypothermia, t = 28 degrees C; (3) pentobarbital, t = 38 degrees C; and (4) isoflurane, t = 38 degrees C. Halothane/N2O was continued in groups 1 and 2, whereas a deep burst-suppression or isoelectric electroencephalogram was achieved with the test drugs in groups 3 and 4. Cerebral metabolic rates were similar in groups 2, 3, and 4. After a baseline dialysis sample was collected, animals were killed with potassium chloride. The time to terminal depolarization was recorded, after which three consecutive 10-min dialysate samples were collected. Glutamate, aspartate, gamma-aminobutyric acid, and glycine concentrations were measured using high-performance liquid chromatography. RESULTS: Times to terminal depolarization were shorter in both pentobarbital and isoflurane groups than with hypothermia (103 +/- 15 and 127 +/- 10 vs. 195 +/- 20 s respectively, mean +/- SD). However, times to terminal depolarization in all three groups were longer than in control subjects (control = 70 +/- 9s). Postdepolarization concentrations of all compounds were lower in hypothermic animals (vs. normothermic control animals), but no reductions in glutamate, aspartate, or glycine concentrations were noted in pentobarbital or isoflurane groups. gamma-Aminobutyric acid concentrations were reduced by both anesthetics, but not to the same degree as with hypothermia. CONCLUSIONS: Pentobarbital and isoflurane prolonged the time to terminal depolarization, but did not influence the rate at which the extracellular concentrations of glutamate, aspartate, or glycine increased. By contrast, hypothermia reduced the release of all excitatory amino acids. These differences may explain the greater protective efficacy of hypothermia in the face of cerebral ischemia.

Anesthetics, Inhalation↗
PubMed1996

Echo-Doppler evaluation of reverse flow sign in the intrahepatic portal branches after surgery.

OBJECTIVE: The author's evaluated the clinical significance of the development of reversed portal flow after abdominal surgery other than portosystemic shunt procedure. SUMMARY BACKGROUND DATA: There have been several reports in regard to reversed portal flow demonstrated by pulsed Doppler ultrasonography, most of which were related to portal hypertension. To the authors' knowledge, this is the first report in which reversed portal flow also is present in patients who have undergone abdominal surgery other than portosystemic shunt procedure. METHODS: Preoperative and postoperative pulsed Doppler ultrasonographic examinations were performed in 126 patients who underwent abdominal surgery. Postoperatively, the portal flow direction was assessed in the right portal branch or the umbilical portion of the left portal branch. RESULTS: Of the 126 patients, reversed portal flow developed in 10 after surgery; 9 of them died of liver failure. CONCLUSIONS: The postoperative development of reversed portal flow is considered to have grave prognostic significance, indicating that the degree of postoperative liver damage is extremely critical.

Adult↗
PubMed1996

Effect of occlusal pressure on the histopathological changes in denture supporting tissues.

Histopathological changes in the denture supporting tissues in relation to the occlusal pressure exerted through an experimental denture base were studied. An experimental denture, which prescribed the occlusal pressure by the amount of subsidence of the denture base (100, 50 and 13 microns), was constructed for the palate of the molar region of rat. Histopathological changes caused by the occlusal pressure were observed, and the intensity of the pressure was also estimated. In the 100 microns subsidence group, compression of epithelium and lamina propria mucosae, inflammatory change and bone resorption were caused by the occlusal pressure. In the 50 microns subsidence group, compression of epithelium and lamina propria mucosae and bone resorption were observed, while in the 13 microns subsidence group, no evidence of inflammatory change and bone resorption were observed. The epithelium and lamina propria mucosae recovered histopathologically depending on the gradual decrease of the occlusal pressure resulting from bone resorption, whereas no quantitative recovery of the resorbed bone tissue was observed in the 100 and 50 microns subsidence groups. From the results observed in this study, a high correlation was observed between the histopathological changes under a denture base and the intensity of the occlusal pressure, and the possibility of the existence of the threshold for bone resorption induced by occlusal pressure was suggested.

Acrylic Resins↗
PubMed1996

Olfactory evoked potentials in Parkinson's disease, Alzheimer's disease and anosmic patients.

Olfactory evoked potential (OEP) recordings were undertaken using amyl acetate stimulation in 20 patients with Parkinson's disease, nine patients with Alzheimer's disease, seven patients with olfactory dysfunction with no other neurological disorder, and 17 control subjects. In order to eliminate the somatosensory factor from the combined somatosensory and olfactory components produced by amyl acetate stimulation, we substracted the potentials using odorless air from those using amyl acetate. In normal subjects, three components were observed, the mean latencies of which were 309 +/- 46, 484 +/- 61 and 710 +/- 55 ms. In all subjects with anosmia (n = 7), no responses were observed. In the patients with Alzheimer's disease, the components were fewer despite having no olfactory dysfunction. In the 20 patients with Parkinson's disease, eight [corrected] patients showed no components, seven patients showed one component and four [corrected] patients showed two components. The components rarely were detected in spite of whether the patients had olfactory dysfunction or not. Olfactory evoked potentials are useful in detecting olfactory dysfunction and the early stages of Alzheimer's disease and Parkinson's disease.

Aged↗