Biomedical subjects

N Nishi

Publications and source records attributed to N Nishi.

At least 37 records · Page 2Linked to original sources

PubMed2000

Synergistic effect of KRN7000 with interleukin-15, -7, and -2 on the expansion of human V alpha 24+V beta 11+ T cells in vitro.

KRN7000, (2S, 3S, 4R)-1-O-(alpha-D-galactopyranosyl)-2-(N-hexacosanoylamino)-1, 3, 4-octadecanetriol, has been shown to prevent tumor metastasis to the liver through the activation of natural killer (NK) T cells in mice. In this study, the proliferation of human NK T cells, which express an invariant T cell antigen receptor (TCR) consisting of a Valpha24 chain and a Vbeta11 chain, was investigated using KRN7000, interleukin (IL)-15, IL-7, and IL-2 in vitro. KRN7000 stimulated the expansion of Valpha24(+)Vbeta11(+) T cells derived from peripheral blood mononuclear cells in a dose-dependent fashion, with some fluctuation between donors. IL-15, IL-7, and IL-2 synergistically stimulated the expansion of Valpha24(+)Vbeta11(+) T cells when combined with KRN7000. Intracellular expression of interferon (IFN)-gamma and IL-4 in Valpha24(+)Vbeta11(+) T cells expanded in the presence of KRN7000 was identified using flow cytometry. Valpha24(+)Vbeta11(+) T cells, expanded in the presence of KRN7000, contained granzyme (Gr) B-positive granules and perforin-positive granules. The addition of IL-15 to the culture containing KRN7000 increased GrB expression in Valpha24(+)Vbeta11(+) T cells while IL-7 and IL-2 failed to do it. In conclusion, the antitumor effect of KRN7000 may depend, in part, on granule-mediated cell killing through the activation of NK T cells and IL-15 may potentiate this effect.

Adjuvants, Immunologic↗

PubMed2000

Pharmacological characterization of metabotropic glutamate receptor-mediated high-affinity GTPase activity in rat cerebral cortical membranes.

Activation of heterotrimeric guanine nucleotide-binding regulatory proteins (G-proteins) functionally coupled to metabotropic glutamate receptors (mGluRs) was assessed by agonist-induced high-affinity GTPase (EC3.6.1.-) activity in rat cerebral cortical membranes. L-Glutamate (1 mM) stimulated high-affinity GTPase activity to the same extent throughout the incubation period up to 20 min, in a Mg(2+)-dependent manner. The addition of 1 mM L-glutamate augmented V(max) of the enzyme activity (1670 to 3850 pmol mg(-1) protein 15 min(-1)) with slight increase in K(M) value (0.26 to 0.63 microM). The high-affinity GTPase activity was stimulated by the following compounds with a rank order of potency of (2S,2'R,3'R)-2-(2', 3'-dicarboxycyclopropyl) glycine (DCG-IV) > (2S,1'S, 2'S)-2-(carboxycyclopyropyl)glycine (L-CCG-I) > L-glutamate > or = 2R, 4R-4-aminopyrrolidine-2,4-dicarboxylate [(2R,4R)-APDC] > 1S, 3R-1-aminocyclopentane-1,3-dicarboxylate [(1S,3R)-ACPD] > (S)-4-carboxy-3-hydroxyphenylglycine [(S)-4C3HPG] > (S)-3-carboxy-4-hydroxyphenylglycine [(S)-3C4HPG] > ibotenate, but not by L-(+)-2-amino-4-phosphonobutyrate (L-AP4), (RS)-3, 5-dihydroxyphenylglycine [(RS)-3,5-DHPG], quisqualate, or L-serine-O-phosphate (L-SOP), indicative of involvement of group II mGluRs, in particular mGluR2. (2S)-alpha-Ethylglutamate (EGLU), a presumably selective antagonist against group II mGluRs, inhibited DCG-IV-stimulated high-affinity GTPase activity in a competitive manner with an apparent K(B) of 220 microM. L-Glutamate-stimulated activity was eliminated by pretreatment of the membranes with sulfhydryl alkylating agent N-ethylmaleimide (NEM) at 30-50 microM, indicating that G-proteins of the G(i) family are involved. These results indicate that mGluR agonist-induced high-affinity GTPase activity in rat cerebral cortical membranes may be used to detect the functional interaction between group II mGluRs, in particular mGluR2, and NEM-sensitive G(i) proteins.

Animals↗

PubMed2000

Accumulation and removal of heavy metal ions by insolubilized-DNA and its interaction.

DNA was immobilized onto a porous glass bead by a treatment with UV irradiation. The immobilized DNA was insoluble in water and used for accumulation of heavy metal ion. When DNA-immobilized glass bead was added into aqueous solution containing heavy metal ions, such as Hg2+, Cd2+, Pb2+, Zn2+, Cu2+ and Fe3+, the concentration of these metal ions in the solution was decreased. However, the concentration of Mg2+ in the solution was not affected by the addition of the DNA-immobilized glass bead. These results suggested that UV-irradiated DNA selectively accumulated heavy metal ions.

Animals↗

PubMed2000

Preparation of insolubilized-DNA film with three-dimensional network and removal of endocrine disruptors.

A water-insolubilized film was prepared by UV irradiation on a dried DNA film. When a UV-irradiated DNA was examined using a circular dichroism spectroscopy, a double stranded structure was observed as well as that of native DNA. The UV irradiated DNA film was also accumulated intercalating reagents. These results suggested that the double stranded structure was involved in the UV irradiated DNA film with a three-dimensional network. The thymine-thymine dimer formation was suggested to be involved in the cross-linking reactions by the polymerization analysis using poly(dA)-poly(dT) and poly(dG)-poly(dC). We also demonstrate the utilization of the UV-irradiated DNA film as a functional material for the accumulation of harmful DNA intercalating pollutants in aqueous solution. These results suggested that the UV-irradiated DNA film was applicable as a functional material for medical, engineering and environmental sciences.

Acridine Orange↗

PubMed2000

Androgen-regulated expression of a novel member of the aldo-keto reductase superfamily in regrowing rat prostate.

The rat prostate is dependent on androgen for normal growth and differentiation. In addition, the organ undergoes rapid cell death upon withdrawal of androgen on castration, and the atrophied tissue is capable of regrowth after androgen replacement in adult animals. In our search for novel factor(s) that participate in this androgen-induced proliferation of adult rat prostate cells, we have generated a complementary DNA (cDNA) library enriched in cDNAs transiently up-regulated after androgen stimulation in castrated rat ventral prostate using a PCR-based subtractive hybridization technique. Sequence analysis of about one hundred clones in the library showed that approximately 70% of them are identical or closely related to genes of known function, the remaining ones showing no or very low similarity to any genes characterized previously. Among the former a new member of the rat aldo-keto reductase superfamily that is closely related to aflatoxin, B1 aldehyde reductase has been identified. The newly identified protein (androgen-inducible aldehyde reductase, AIAR) and rat aflatoxin B1 aldehyde reductase (AFAR) exhibit 80% amino acid sequence homology. The enzymatic activity toward 4-nitrobenzaldehyde of recombinant AIAR expressed in Escherichia coli was about 16% of that of rat AFAR. Northern blot analysis revealed AIAR expression in various adult rat tissues in addition to the ventral and dorsolateral prostates, which differs from the highly restricted expression of AFAR in the kidney and liver. The AIAR messenger RNA (mRNA) content of the ventral prostate was low in normal and castrated rats, transiently increased after androgen administration to castrated rats, attaining a peak 12-24 h after the treatment. Although the physiological substrate(s) of AIAR has not been identified, the current results suggest that AIAR expression is associated with some growth-related processes in regrowing rat prostate.

Aflatoxin B1↗

PubMed2000

Stimulation of high-affinity GTPase activity through group II metabotropic glutamate receptors in rat hippocampal and striatal membranes.

The stimulation of high-affinity GTPase activity through metabotropic glutamate receptors (mGluRs) was pharmacologically characterized with the use of a series of agonists for mGluRs in rat hippocampal and striatal membranes. The pharmacological profile of the response was almost identical to each other between both brain regions. Thus, the high-affinity GTPase activities were stimulated by several mGluR-related compounds with the following rank order of potency: (2S,2'R,3'R)-2-(2',3'-dicarboxycyclopropyl)glycine (DCG-IV) = (2S,1'S,2'S)-2-(carboxycyclopropyl)glycine (L-CCG-I) > L-glutamate = 2R,4R-4-aminopyrrolidine-2,4-dicarboxylate [(2R,4R)-APDC] > (S)-4-carboxy-3-hydroxyphenylglycine [(S)-4C3HPG] = 1S,3R-1-aminocyclopentane-1,3-dicarboxylate [(1S,3R)-ACPD] > (S)-3-carboxy-4-hydroxyphenylglycine [(S)-3C4HPG] = ibotenate. The negative logarithmically transformed EC50 (pEC50) values of these compounds in both brain regions were significantly correlated with those reported previously in the cerebral cortical membranes (N. Nishi et al., Br. J. Pharmacol., 130, 1664-1670, 2000). On the contrary, other reagents including a selective group I mGluRs agonist, (RS)-3,5-dihydroxyphenylglycine [(RS)-3,5-DHPG], and selective group III mGluRs agonists such as L(+)-2-amino-4-phosphonobutylate (L-AP4) and L-serine-O-phosphate (L-SOP) had little or no effects even at the highest concentration examined. Quisqualate was also a very weak agonist in both regions. These results indicate that mGluR-mediated high-affinity GTPase activity derives from the Gi proteins associated with adenylyl cyclase inhibition through group II mGluRs, in particular the mGluR2 subtype, in rat hippocampal and striatal membranes.

Animals↗

PubMed2000

Collaborative work to evaluate toxicity on male reproductive organs by repeated dose studies in rats 3). Effects of repeated doses of ethinylestradiol for 2 and 4 weeks on the male reproductive organs.

Male Sprague-Dawley rats were subcutaneously administered 0.3 and 3.0 mg/kg/day of ethinylestradiol for 2 and 4 weeks. Two weeks treatment decreased body weight gain, food consumption, absolute weights of testis, epididymis, prostate and seminal vesicle, and relative weights of epididymis, prostate and seminal vesicle. On the other hand, it increased absolute and relative weights of pituitary and adrenal glands, and induced atrophy of Leydig cells, degeneration/necrosis of pachytene spermatocytes, vacuolar degeneration of Sertoli cells, and retention of spermatids. In addition to the changes found after 2 weeks treatment, 4 weeks treatment induced exfoliation of germinal cells, decreases in spermatid and multinucleated giant cell formation and relative weights of testis. These results suggest that examination of prostate and seminal vesicle weights and histopathological changes in the testis are important for evaluation of male reproductive toxicity of ethinylestradiol and 2 weeks treatment is sufficient to detect toxicity on male reproductive organs.

Adrenal Glands↗

PubMed2000

[Radiation dose measurement of the patient in interventional radiology using a transmission ionization chamber].

We propose a method to estimate patient radiation dose in radiologically guided interventional procedures using a transmission ionization chamber. A typical transarterial embolization (TAE) procedure for hepatocellular carcinoma was simulated, including 30 minutes of fluoroscopy and five series of DSA, each with appropriate collimation. The dose-area product was divided by the area and compared with values from a standard dosimeter placed in the center of the radiation entrance, to obtain a conversion factor. In this way, the entrance skin dose can be estimated immediately after the procedure by simply multiplying the value by the conversion factor, if the procedure roughly conforms to the simulated model. The average entrance skin dose of 33 patients who recently underwent TAE for HCC was found to be 0.66 (0.19-1.75) Gy. This technique can be applied to other areas of IVR and may help to reduce patient exposure to radiation.

Carcinoma, Hepatocellular↗

PubMed2000

[A surgical case of growing cavernous angioma at the pontomedullary junction].

We described a surgical case of growing cavernous angioma located at the pontomedullary junction. This 52-year-old woman presented with symptoms caused by a small hemorrhage in the right cerebellopontine angle. Magnetic resonance images (MRI) suggested cavernous angioma as the underlying pathology. 9 months after the first episode, the second hemorrhage occurred with a deteriorated neurological state that disappeared under conservative treatment except for right facial paresis and hearing disturbance. During careful observation for 1 year, the size of the lesion gradually increased on MRI and additional neurological deficits including left hemiparesis and right abducent nerve palsy were diagnosed. The first operation was carried out through the right lateral suboccipital approach, but only partial removal of the cavernous angioma was accomplished due to the overlying seventh and lower cranial nerves. After more than 4 months, a third hemorrhagic episode was presented with a sudden onset of right cerebellar signs and facial numbness. The cavernous angioma grew in size to reach the ventrolateral corner of the 4th ventricle with dense hemosiderin deposition around the core lesion on MRI. An enhancement inside the lesion was also demonstrated after gadolinium-diethylenetriaminepenta-acetic acid administration. The second operation through the midline suboccipital approach was selected for the complete resection of the residual cavernous angioma. The lesion was too hard to resect without internal decompression. The pontine part of the lesion was almost totally resected, but manipulation for the medullary part to create a discrete layer between the lesion and surrounding neural tissues was unsuccessful and generated severe bradycardia, so this part of the cavernous angioma had to be left. The problems for the management of cavernous angioma in the brain stem should be discussed, especially focussing on the surgical indication in reference to our experience and previous literatures.

Brain Stem Neoplasms↗

PubMed2000

Beta-cyclodextrin-linked chitosan beads: preparation and application to removal of bisphenol A from water.

Water-insoluble and highly porous chitosan beads having an ability to form inclusion complexes have been synthesized by treatment of a solution of chitosan in aqueous acetic acid with aqueous NaOH followed by crosslinking and reductive alkylation with 2-O-formylmethyl-beta-cyclodextrin. Preliminary experiments for its application to removal of endocrine disrupting chemicals were carried out using a column of the resulting beads and bisphenol A as the model substrate.

Benzhydryl Compounds↗

PubMed1999

Mechanism of salmon sperm decondensation by nucleoplasmin.

Removal of protamine from DNA-protamine (salmine, protamine from salmon sperm) complexes by nucleoplasmin was examined and compared with that of poly-L-glutamic acid (PLGA) using turbidity and ethidium bromide (EB) treatment methods. When nucleoplasmin or PLGA was added to a DNA-protamine complex solution, turbidity was decreased and the amount of EB intercalated into DNA was increased. These results suggest that nucleoplasmin and PLGA can remove protamine from DNA-protamine complexes. The effect of nucleoplasmin was more potent than that of PLGA. Direct interaction of nucleoplasmin with protamine was confirmed by mixing experiments using circular dichroism (CD) and fluorescence spectroscopies. Results suggest that nucleoplasmin is bound to protamine in a 1:1 ratio and that Trp126 is located near a hydrophilic region containing a polyglutamic acid tract of nucleoplasmin which was obviously influenced by its binding with protamine. It would appear that the polyglutamic acid tract in nucleoplasmin plays a critical role for binding with protamine.

Animals↗

PubMed1999

Effects of alpha-galactosylceramide (KRN7000), interleukin-12 and interleukin-7 on phenotype and cytokine profile of human Valpha24+ Vbeta11+ T cells.

The alpha-galactosylceramide KRN7000 was reported to be presented by CD1d to natural killer (NK) T cells, cells that are thought to play an important role in the rejection of malignant tumours and in the regulation of several autoimmune diseases. Here we analysed human peripheral blood (PB) NK T cells (Valpha24+ Vbeta11+ T cells) before and after a short-term culture in the presence of KRN7000. KRN7000 strongly activated PB Valpha24+ Vbeta11+ T cells and, when stimulated, the vast majority of these cells expressed interferon-gamma (IFN-gamma). Exposure of these KRN7000-cultured Valpha24+ Vbeta11+ T cells to interleukin-12 (IL-12), but not to IL-7, resulted in a relative increase in IFN-gamma-expressing Valpha24+ Vbeta11+ T cells, compared with IL-4-expressing Valpha24+ Vbeta11+ T cells, indicating a shift towards a T-helper type 1 (Th1) phenotype. KRN7000 strongly up-regulated the expression of the cytotoxic molecule granzyme B (GrB) in Valpha24+ Vbeta11+ T cells. Although IL-7 resulted in a decrease in GrB levels in KRN7000-cultured Valpha24+ Vbeta11+ T cells, IL-12 increased GrB levels in both Valpha24+ Vbeta11+ T cells and in Valpha24+ Vbeta11+ T-cell clones and increased cytotoxicity against hCD1d-transfected HeLa cells. Our data provide further insight into the characteristics of human Valpha24+ Vbeta11+ T cells and indicate that KRN7000 is a potent activator of Valpha24+ Vbeta11+ T cells. Combined with the established anti-tumour effects of KRN7000 in mouse models, these results may support the use of KRN7000 as an anti-tumour agent in man.

Adult↗

PubMed1999

Immobilization of DNA by UV irradiation and its utilization as functional materials.

The water-insoluble DNA film was successfully prepared by UV irradiation. The DNA film was stable in water. It could effectively accumulated the DNA-binding intercalating materials, such as ethidium bromide, dibenzo-p-dioxin and benzo[a]pyrene, in their aqueous solutions. On the other hand, DNA was immobilized onto nonwoven cellulose fabrics, also by the UV irradiation. The DNA immobilized cloth was found to bind silver ions. The DNA-cloth containing silver ion showed antibacterial activity. The water-insoluble DNA prepared by UV irradiation has a potential ability to serve as biomaterials for medical, engineering and environmental objects.

Animals↗

PubMed1999

[Functional coupling between metabotropic glutamate receptors and G proteins in rat cerebral cortex].

Metabotropic glutamate receptors (mGluRs) are widely distributed in mammalian brain, and are classified into three groups (Group I-III) according to mode of action: by I) homology of amino acid sequence, II) ligand selectivity, and III) signal transduction pathway. The mGluR-mediated signaling cascade is mainly investigated with the use of receptor-expressed non-neuronal cells; and thus, signaling mechanism in the central nervous systems remains to be elucidated. The aim of this study was to elucidate the manner of mGluR-G protein coupling in rat brain by measuring the activities of the high-affinity, low-KM GTPases in G alpha proteins. The selective Group II mGluR agonists, i.e., 2-(2,3-dicarboxycyclopropyl)glycine and (2R,4R)-4-aminopyrrolidine-2,4-dicarboxylate, elevated GTP hydrolysis in a concentration-dependent and saturable manner. On the other hand, the activation of high-affinity GTPase by the selective Group I mGluR agonist, (S)-3-hydroxyphenylglycine, or the selective Group III agonist, L-2-amino-4-phosphonobutylate, was hardly detected. These results indicated that the fashion of mGluR-G protein coupling varies among the mGluR subgroups. It is also suggested that high-affinity GTPase assay is useful for the investigation of mGluR-mediated signal transduction in the brain.

Animals↗

PubMed1999

Activation of G proteins by neuropeptide Y and gamma-aminobutyric acid(B) receptor agonists in rat cerebral cortical membranes through distinct modes of action.

The neuropeptide Y (NPY)-elicited increase in high-affinity GTPase activity in the rat cerebral cortical membranes was assayed and compared with the gamma-aminobutyric acid (GABA)(B) receptor-mediated response, representative of the conventional receptor-dependent mode of G protein activation. GABA and a selective GABA(B) receptor agonist, (+/-)-baclofen, stimulated the high-affinity GTPase activity in a concentration-dependent and saturable manner, with a strict Mg(2+) dependence. On the other hand, NPY (10 microM)-stimulated high-affinity GTPase activity was detectable even in the absence of Mg(2+). The concentration-response curve for NPY-induced increase in high-affinity GTPase activity in the presence of 2 mM MgCl(2) revealed a biphasic pattern, and NPY (100 nM)-stimulated activity was dependent on MgCl(2). In the presence of 2 mM MgCl(2), the increase in high-affinity GTPase activity by 100 nM NPY was almost fully inhibited by a selective NPY Y-1 receptor antagonist, (R)-N(2)-(diphenylacetyl)-N-[(4-hydroxyphenyl)methyl]argininami de (BIBP3226), whereas the effect of 10 microM NPY was only partially antagonized by this compound. The increase in the activity by 10 microM NPY in the absence of MgCl(2) was not at all inhibited by BIBP3226. The high-affinity GTPase activity was augmented by [Leu(31),Pro(34)]NPY (porcine) but not by desamido-NPY, NPY(13-36) (porcine), or rat pancreatic polypeptide at submicromolar concentrations. These results indicate that NPY activates G proteins through two distinct modes of action: the conventional receptor-mediated pathway through NPY Y-1 receptor subtype dominant in the presence of the lower concentrations of NPY and receptor-independent, direct G protein activation driven by the higher concentrations of NPY.

Animals↗

PubMed1999

[Table-moving contrast-enhanced MR angiography of abdominal aortic aneurysm].

Table-moving contrast-enhanced MR angiography (MRA) was performed in 14 cases of abdominal aortic aneurysm to evaluate its clinical usefulness. In all cases, aneurysms were clearly demonstrated and image quality was clinically acceptable. Findings of reconstructed MRA were highly consistent with those of DSA, and thrombosed areas were confirmed on source images. Main aortic branches including renal arteries, common iliac arteries, and internal and external iliac arteries were readily identified on reconstructed MRA and/or source images. Additional findings such as thoracic aortic aneurysm (n = 1), common iliac aneurysm (n = 6), external iliac aneurysm (n = 1), internal iliac aneurysm (n = 1), femoral arterial obstruction (n = 2), and femoral arterial stenosis (n = 4) were also detected. Although table-moving MRA may have disadvantages like reduced blood signal and limited spatial resolution compared with the conventional contrast-enhanced technique, the images that were obtained provided sufficient contrast and resolution for preoperative evaluation. Because abdominal aortic aneurysm is accompanied by various arterial abnormalities in many of the large arteries, table-moving MRA was considered a suitable technique for comprehensive assessment.

Aged↗

PubMed1998

Collagen-binding growth factors: production and characterization of functional fusion proteins having a collagen-binding domain.

The autocrine/paracrine peptide signaling molecules such as growth factors have many promising biologic activities for clinical applications. However, one cannot expect specific therapeutic effects of the factors administered by ordinary drug delivery systems as they have limited target specificity and short half-lives in vivo. To overcome the difficulties in using growth factors as therapeutic agents, we have produced fusion proteins consisting of growth factor moieties and a collagen-binding domain (CBD) derived from Clostridium histolyticum collagenase. The fusion proteins carrying the epidermal growth factor (EGF) or basic fibroblast growth factor (bFGF) at the N terminal of CBD (CBEGF/CBFGF) tightly bound to insoluble collagen and stimulated the growth of BALB/c 3T3 fibroblasts as much as the unfused counterparts. CBEGF, when injected subcutaneously into nude mice, remained at the sites of injection for up to 10 days, whereas EGF was not detectable 24 h after injection. Although CBEGF did not exert a growth-promoting effect in vivo, CBFGF, but not bFGF, strongly stimulated the DNA synthesis in stromal cells at 5 days and 7 days after injection. These results indicate that CBD may be used as an anchoring unit to produce fusion proteins nondiffusible and long-lasting in vivo.

3T3 Cells↗

PubMed1998

Measurement of receptor-mediated functional activation of G proteins in postmortem human brain membranes.

Guanine nucleotide-binding regulatory proteins (G proteins) play a pivotal role in receptor-mediated transmembrane signal transduction, and have been implicated in modes of action of psychotropic drugs as well as in pathogenesis of psychiatric disorders. In the present investigation, functional activation of G proteins coupled with several receptors, in particular with GABAB receptors, was assessed by agonist-induced stimulation of high-affinity GTPase, an enzyme that is intrinsic to alpha subunit of G protein, in postmortem human frontal cortical membranes. High-affinity GTPase activity was stimulated by GABA as well as (+/-)-baclofen, a selective GABAB receptor agonist, with EC50 values of 60-150 and 10-40 microM, respectively, in a Mg(2+)-dependent manner. The (+/-)-baclofen-stimulated response was antagonized by the selective GABAB receptor antagonist, 2-hydroxy-saclofen, in a competitive manner with a KB value of 59 microM. Although the maximal percent increase above basal value (% Emax) for GABAB receptor-mediated high-affinity GTPase activity was varied from subject to subject, % Emax values for both agonists were highly correlated with each other, and replicable and stable in a given subject, indicating that this measure is trustworthy as an index of functional coupling between receptors and G proteins in future studies at the aim of elucidating possible alteration of receptor/G protein interaction in psychiatric disorders. The % Emax values for GABAB receptor-mediated responses were correlated inversely with brain storage duration, which should be critically considered in postmortem studies. The increases in high-affinity GTPase activity stimulated by several agonists other than GABAB receptor agonists seemed too low to quantify for making a comparison in future studies.

Aged↗