Biomedical subjects

T Yoshimoto

Publications and source records attributed to T Yoshimoto.

At least 163 records · Page 9Linked to original sources

PubMed1999

IL-18, although antiallergic when administered with IL-12, stimulates IL-4 and histamine release by basophils.

IL-18 is a proinflammatory cytokine that plays an important role in natural killer cell activation and T helper 1 (Th1) cell responses. Mast cells and basophils are major inducers and effectors of allergic inflammation. Here we show that basophils and mast cells derived by culture of bone marrow cells with IL-3 for 10 days express IL-18Ralpha chain and that basophils produce large amounts of IL-4 and IL-13 in response to stimulation with IL-3 and IL-18. Injection of IL-12 and IL-18 inhibits IgE production in helminth-infected wild-type mice and abolishes the capacity of their basophils to produce IL-4 and IL-13 in response to stimulation either with IL-3 and IL-18 or with FcepsilonR cross-linkage. By contrast, this combination of cytokines actually increases IgE levels in helminth-infected IFN-gamma(-/-) mice and enhances IL-4 and IL-13 production by their basophils. Furthermore, injection of IL-18 alone enhances basophil production of IL-4 and histamine both in wild-type and IFN-gamma(-/-) mice. Thus, IL-18 has the potential to stimulate basophils but, when given with IL-12, exhibits an antiallergic action in vivo.

Animals↗

PubMed1999

Activation of matrix metalloproteinase-2 in human breast cancer cells overexpressing cyclooxygenase-1 or -2.

Human breast cancer cell line Hs578T was stably transfected with cDNA for cyclooxygenase-1 or -2. When the cells overexpressing cyclooxygenase-1 or -2 were stimulated with concanavalin A, the processing of matrix metalloproteinase-2 was observed with the aid of gelatin zymography. This processing was not seen in mock-transfected and original cells which did not express detectable cyclooxygenase activity. Furthermore, Northern blotting showed 8-13 fold induction of membrane-type 1 matrix metalloproteinase which processed matrix metalloproteinase-2 in the cells expressing cyclooxygenases. These findings suggest that both isoforms of cyclooxygenase mediate the processing of matrix metalloproteinase-2 through induction of membrane-type I metalloproteinase in breast cancer cells.

Breast Neoplasms↗

PubMed1999

Posttreatment with the immunosuppressant cyclosporin A in transient focal ischemia.

Cyclosporin A (CsA) reduces ischemic brain damage when administered in such a way that its penetration across the blood-brain barrier is enhanced. Since only pretreatment has previously been used in focal ischemia, the objective of the present study was to establish whether posttreatment is efficacious and to assess the window of therapeutic opportunity for CsA. To that end, CsA was given 5 min to 6 h after the start of reperfusion following 2 h transient ischemia, and infarct volume was assessed after 48 h by triphenyltetrazolium chloride staining. Attempts were made to circumvent the BBB to CsA by an intracerebral needle lesion, by an increase in the intravenous CsA dose, or by osmotic opening with intracarotid mannitol. The results were compared to those obtained with FK506. Intravenous CsA in a dose of 10 mg/kg failed to reduce infarct volume, unless preceded by a needle lesion. That procedure, and an increase in CsA dose to 50 mg/kg, reduced infarct volume to about 50% of control, but the higher dose had toxic side effects. The coupled intracarotid infusion of mannitol and CsA (10 mg/kg) was more efficacious, without overt side effects. However, mannitol proved dispensable since CsA alone reduced infarct volume to 30% of control, with a therapeutic window of 3-6 h. When given after 5 min of reflow, CsA reduced infarct volume to 10% of control and was clearly more neuroprotective than FK506. Possibly, this is because CsA blocks the mitochondrial permeability transition pore which is opened under adverse conditions.

Animals↗

PubMed1999

Induction of antitumor immunity with Fas/APO-1 ligand (CD95L)-transfected neuroblastoma neuro-2a cells.

Fas/Apo-1 (CD95)-Fas ligand (FasL) system has been implicated in the suppression and stimulation of immune responses. We examined the induction of antitumor immunity with neuroblastoma Neuro-2a cells transfected with FasL cDNA (Neuro-2a+FasL). Neuro-2a+FasL cells expressed FasL on the cell surface and secreted soluble FasL. Histologic and flow cytometric analyses revealed that Neuro-2a+FasL cells caused neutrophils to infiltrate into the injected site, resulting in strong inflammation. Neutrophil infiltration was inhibited by treatment with anti-FasL mAb and did not occur in Fas-deficient lpr mice. Normal syngeneic mice rejected Neuro-2a+FasL cells after the inflammation and acquired tumor-specific protective immunity. CD8+ T cells were responsible for the antitumor immunity. Neuro-2a+FasL cells formed tumors after far longer latency compared with mock-transfected Neuro-2a+Neo cells in nude mice, and immune competent mice rejected Neuro-2a cells but not sarcoma S713a cells when they were injected with Neuro-2a+FasL cells in a mixture. These results suggest that neutrophils attracted through the Fas-FasL system may impair tumor cells by inflammation at the initial step, followed by development of CD8+ T cell-dependent tumor-specific antitumor immunity, leading to complete eradication of tumor cells. Importantly, the treatment with Neuro-2a+FasL cells exhibited therapeutic efficacy against growing tumors.

Animals↗

PubMed1999

Activation of Arc gene, a dendritic immediate early gene, by middle cerebral artery occlusion in rat brain.

The effect of middle cerebral artery (MCA) occlusion on the activity-regulated cytoskeleton-associated protein (Arc) mRNA expression has been investigated using in situ hybridization. It was induced in the extensive regions of cerebral cortex, medial striatum, and distant areas such as the ipsilateral lateral septal nucleus, bilateral hippocampal formation and contralateral amygdala following MCA occlusion. In the hippocampal formation, it was induced in the granule cell layer and the stratum pyramidale at 1 h and in the molecular layer and in the stratum oriens and stratum radiatum bilaterally at 4 h. MK-801 pretreatment strongly attenuated the induction of Arc mRNA. The present results suggest that Arc may play an important role in the neuronal plasticity through NMDA activation following focal cerebral ischemia.

Animals↗

PubMed1999

Enhancing effect of tumor necrosis factor (TNF)-alpha, but not IFN-gamma, on the tumor-specific cytotoxicity of gammadeltaT cells from glioblastoma patients.

Adoptive immunotherapy using tumor-specific killer cells can be beneficial in inducing regression of advanced cancer. The roles of cytokines on effector cells in inducing maximal killing activity and the accompanying side-effects should be investigated in vitro and fully understood prior to their clinical use. The present study indicates that the gammadeltaT cells involved in autologous tumor-specific killing consist of several populations in terms of their T cell receptor (TCR) repertoire, but predominantly express the products of the Vgamma9/Vdelta2 gene locus of the TCR. We then examined the effect of TNF-alpha and IFN-gamma on these tumor-specific gammadeltaT cells for possible clinical use in cancer patients. TNF-alpha alone, at concentrations of 0.01-1.0 microg/ml, caused increased gammadeltaT cell cytotoxicity against autologous glioblastoma cells, whereas IFN-gamma alone had no effect. The combination of TNF-alpha (1 microg/ml) with IL-2 (50 units/ml) resulted in further enhancement of cytotoxicity. TNF-alpha, but not IFN-gamma, marginally inhibited the proliferative response of gammadeltaT cells; a similar result was seen when the cytokines were combined. TNF-alpha may, therefore, be one cytokine capable of inducing increased autologous tumor-specific activity in gammadeltaT cells, bearing mainly Vgamma9/Vdelta2 chains, which can be enhanced when combined with other cytokines.

Cell Division↗

PubMed1999

Growth stimulation and induction of epidermal growth factor receptor by overexpression of cyclooxygenases 1 and 2 in human colon carcinoma cells.

There are two isoforms of cyclooxygenase (COX), COX-1 and COX-2. Recent epidemiological and experimental studies indicated a close relationship between COXs and the pathogenesis of colorectal cancer. The purpose of this study was to investigate the possible roles of both isoforms in the proliferation of colon carcinoma cells. A human colon carcinoma cell line, COLO 320DM, was transfected with an eukaryotic expression vector carrying cDNA of either COX-1 or COX-2, the expression of which was driven by a powerful elongation factor-1alpha promoter in pEF-BOS. Both COX-1- and COX-2-expressing cells possessed a similar enzyme activity, 8-10 nmol/10 min per mg protein. Growth rates of both cell lines were stimulated by about 2-fold during a course of culture for 7 days as compared with mock-transfected cells. Although COX-1 and COX-2 are believed to have fundamentally different biological roles, essentially no differences in growth stimulation were observed between the COX-1 and COX-2 overexpressions in our experiments. The reason may be explained by high levels of COX expression, and subtle differences between the both cell lines would be possibly apparent by lower expression levels. The stimulated growth of the COX-transfected cells was accompanied by increased DNA synthesis as assessed by [3H]thymidine incorporation. Furthermore, expression of epidermal growth factor receptor was markedly increased in these cells as examined by reverse transcription-polymerase chain reaction. A COX inhibitor, indomethacin, suppressed the stimulated growth, increased DNA synthesis and induction of epidermal growth factor receptor in COX-1- and COX-2-transfected cells.

Cell Division↗

PubMed1999

Leukotriene A synthase activity of purified mouse skin arachidonate 8-lipoxygenase expressed in Escherichia coli.

Mouse skin 8-lipoxygenase was expressed in COS-7 cells by transient transfection of its cDNA in pEF-BOS carrying an elongation factor-1alpha promoter. When crude extract of the transfected COS-7 cells was incubated with arachidonic acid, 8-hydroxy-5,9,11, 14-eicosatetraenoic acid was produced as assessed by reverse- and straight-phase high performance liquid chromatographies. The recombinant enzyme also reacted on alpha-linolenic and docosahexaenoic acids at almost the same rate as that with arachidonic acid. Eicosapentaenoic and gamma-linolenic acids were also oxygenated at 43% and 56% reaction rates of arachidonic acid, respectively. In contrast, linoleic acid was a poor substrate for this enzyme. The 8-lipoxygenase reaction with these fatty acids proceeded almost linearly for 40 min. The 8-lipoxygenase was also expressed in an Escherichia coli system using pQE-32 carrying six histidine residues at N-terminal of the enzyme. The expressed enzyme was purified over 380-fold giving a specific activity of approximately 0.2 micromol/45 min per mg protein by nickel-nitrilotriacetate affinity chromatography. The enzymatic properties of the purified 8-lipoxygenase were essentially the same as those of the enzyme expressed in COS-7 cells. When the purified 8-lipoxygenase was incubated with 5-hydroperoxy-6,8,11, 14-eicosatetraenoic acid, two epimers of 6-trans-leukotriene B4, degradation products of unstable leukotriene A4, were observed upon high performance liquid chromatography. Thus, the 8-lipoxygenase catalyzed synthesis of leukotriene A4 from 5-hydroperoxy fatty acid. Reaction rate of the leukotriene A synthase was approximately 7% of arachidonate 8-lipoxygenation. In contrast to the linear time course of 8-lipoxygenase reaction with arachidonic acid, leukotriene A synthase activity leveled off within 10 min, indicating suicide inactivation.

Animals↗

PubMed1999

The crystal structure of pyroglutamyl peptidase I from Bacillus amyloliquefaciens reveals a new structure for a cysteine protease.

BACKGROUND: The N-terminal pyroglutamyl (pGlu) residue of peptide hormones, such as thyrotropin-releasing hormone (TRH) and luteinizing hormone releasing hormone (LH-RH), confers resistance to proteolysis by conventional aminopeptidases. Specialized pyroglutamyl peptidases (PGPs) are able to cleave an N-terminal pyroglutamyl residue and thus control hormonal signals. Until now, no direct or homology-based three-dimensional structure was available for any PGP. RESULTS: The crystal structure of pyroglutamyl peptidase I (PGP-I) from Bacillus amyloliquefaciens has been determined to 1.6 A resolution. The crystallographic asymmetric unit of PGP-I is a tetramer of four identical monomers related by noncrystallographic 222 symmetry. The protein folds into an alpha/beta globular domain with a hydrophobic core consisting of a twisted beta sheet surrounded by five alpha helices. The structure allows the function of most of the conserved residues in the PGP-I family to be identified. The catalytic triad comprises Cys144, His168 and Glu81. CONCLUSIONS: The catalytic site does not have a conventional oxyanion hole, although Cys144, the sidechain of Arg91 and the dipole of an alpha helix could all stabilize a negative charge. The catalytic site has an S1 pocket lined with conserved hydrophobic residues to accommodate the pyroglutamyl residue. Aside from the S1 pocket, there is no clearly defined mainchain substrate-binding region, consistent with the lack of substrate specificity. Although the overall structure of PGP-I resembles some other alpha/beta twisted open-sheet structures, such as purine nucleoside phosphorylase and cutinase, there are important differences in the location and organization of the active-site residues. Thus, PGP-I belongs to a new family of cysteine proteases.

Amino Acid Sequence↗

PubMed1999

Induction of Rheb mRNA following middle cerebral artery occlusion in the rat.

Rheb is a recently identified member of the Ras super-family and is an immediate early gene that is rapidly and transiently induced in the hippocampal granule cells by NMDA-dependent synaptic activity in the long term potentiation paradigm. The close homologies with Ras and its rapid inducibility strongly suggest that Rheb shares many biochemical and signaling properties with Ras. The present study investigated the effect of middle cerebral artery (MCA) occlusion on the expression of Rheb mRNA in the rat brain. In situ hybridization autoradiography showed that Rheb mRNA was induced in the extensive regions of cerebral cortex and medial striatum surrounding the ischemic region and bilateral hippocampal formation following MCA occlusion. The induction of Rheb mRNA in the cingulate cortex persisted prominently at 24 h of MCA occlusion. Although the Rheb mRNA induction in the medial striatum and hippocampal formation decreased after 8h of occlusion, it still remained significant at 24h of occlusion. The data suggest the possibility that Ras signaling pathways can be implicated in the cerebral ischemia-elicited events through NMDA receptor activation.

Animals↗

PubMed1999

Continuous antibody production by phytohemagglutinin-L-aggregated hybridoma cells.

Phytohemagglutinin-L (PHA-L) induced aggregation of SP2 myeloma and antibody-producing hybridoma cells. The aggregates were of diverse shapes, and major-axis length of the hybridoma aggregates was mostly 50-80 microm at 1 microg/ml PHA-L and 100-150 microm at 5 microg/ml. PHA-L did not suppress growth rate at these concentrations. The aggregated cells had almost the same antibody productivity as that of non-aggregated cells in a static culture. Essentially, identical results were obtained with soybean agglutinin (SBA). On the other hand, pokeweed mitogen (PWM) did not induce apparent aggregation at a concentration of 10 microg/ml. These results suggest that lectin binding to particular carbohydrate moiety on the cell surface is necessary for cell agglutination. Using PHA-L, a 200-ml suspension culture of aggregated hybridoma cells was successfully performed in a spinner flask over 10 days. The aggregates were mainly globular with a diameter of 50-100 microm at 1-2 microg/ml PHA-L. The aggregation greatly enhanced settlement of hybridoma cells by gravity, and medium exchanges were thereby easily performed in a short period. During a course of the semi-continuous culture, antibody concentrations of culture medium were maintained at approximately 10 microg/ml which was comparable to that of static culture of the aggregated hybridoma cells. Thus, the lectin aggregation is applicable to the separation of culture medium from anchorage-independent cells like hybridomas, and can be employed in a large-scale commercial production of biologically active proteins.

Animals↗

PubMed1999

Cloning of a novel prolidase gene from Aureobacterium esteraromaticum.

The prolidase gene from Aureobacterium esteraromaticum was cloned and expressed in Escherichia coli. The cloned enzyme had the same enzymatic properties as the wild-type enzyme. Kinetic analysis of the enzyme indicated that the best substrate was Pro-Hyp, which was not hydrolyzed by other prolidases. Interestingly, there was no homology between the deduced amino acid sequence of A. esteraromaticum prolidase and those of the other sources such as human E. coli and Lactobacillus. However, homology was seen with the yeast hypothetical protein YJL213w, the function of which is unknown. These findings indicate that the A. esteraromaticum prolidase is a novel enzyme different from other prolidases reported to date.

Amino Acid Sequence↗

PubMed1999

Accuracy and limitation of functional magnetic resonance imaging for identification of the central sulcus: comparison with magnetoencephalography in patients with brain tumors.

The aim of the present study was to clarify the accuracy and limitation of functional magnetic resonance imaging (fMRI) for the identification of the central sulcus affected by brain tumors. Twelve normal volunteers and 11 patients with intracranial tumors adjacent to the central sulcus underwent fMRI and magnetoencephalography (MEG). Three patients were evaluated again after surgery. fMRI was performed with a 1.5 Tesla scanner during repetitive opening and closing of each hand. Cross-correlation function was used to identify activation areas, and the central sulcus was defined as the nearest sulcus to the highest activation spots that were determined by elevating correlation coefficient threshold. Somatosensory-evoked fields were measured using a whole head MEG system. The central sulcus was defined as the nearest sulcus to the N20m for the median nerve stimulus. fMRI and MEG coincided in defining the central sulcus in all 24 hemispheres of volunteers and all 10 examined nonaffected hemispheres of patients. The fMRI-defined central sulcus coincided with the MEG-defined central sulcus in nine (82%) but did not in two (18%) affected hemispheres of patients. The preoperative mismatch disappeared after surgery in one of the two patients. The present study indicates that fMRI successfully defined the central sulcus in most of the patients with brain tumors. However, in a few cases, fMRI was not reliable probably due to venous flow changes by tumor compression and/or compensational activity by brain tissues surrounding the primary sensorimotor cortex. For precise functional assessment of the brain affected by intracranial tumors, combination of fMRI and MEG will be recommended.

Adult↗

PubMed1999

Cerebral blood-flow responses to induced hypotension and to CO2 inhalation in patients with major cerebral artery occlusive disease: a positron-emission tomography study.

Our aim was to study the relationship between cerebral blood flow (CBF) responses to induced hypotension and to CO2 inhalation in patients with occlusive disease of the carotid or middle cerebral arteries. In 13 patients (8 men, 5 women) aged 31-73 years (mean +/- 1 SD = 63.2 +/- 10.6), regional CBF values during the resting state (CBFrest), 7% CO2 inhalation (CBFhypercapnia), and hypotension induced by 10-20 microg/kg/min intravenous trimethaphan (CBFhypotension) were measured using positron-emission tomography (PET) with H2(15)O. The % CBF change during induced hypotension (% CBFhypotension) was defined as (CBFhypotension - CBFrest)/CBFrest multiplied by 100. The % CBF change during CO2 inhalation (% CBFhypercapnia) was defined as (CBFhypercapnia - CBFrest)/CBFrest/mm Hg arterial partial pressure of CO2 x 100. We defined symptomatic hemispheres as those with a stenotic or occlusive lesion with neurological symptoms or signs and asymptomatic hemispheres as those which had a similar lesion and/or were influenced by the collateral flow pattern without neurological symptoms. In the territory of the occlusive lesion, % CBFhypotension correlated significantly with % CBFhypercapnia (r = 0.793, P < 0.002) in the symptomatic hemispheres. In the brain regions in which trimethaphan did not induce a reduction in CBF. % CBFhypercapnia was 6.13 +/- 1.79. In those in which % CBFhypotension ranged from 0 to -5, from -5 to -10, and more than -10%, % CBFhypercapnia was 4.05 +/- 1.99, 3.21 +/- 1.17, and 1.73 +/- 1.61, respectively, with significant differences between each pair of groups. In the asymptomatic hemispheres, % CBFhypotension also correlated with % CBFhypercapnia (r = 0.979, P < 0.0001). Failure to maintain CBF during induced hypotension was associated with diminished cerebrovascular vasoreactivity to hypercapnia in patients with arterial disease. This may indicate that failure of autoregulation can be assessed by the CBF response to both induced hypotension and CO2 inhalation. From the technical point of view, estimation of the CO2 response may be useful for assessing failure of autoregulation.

Administration, Inhalation↗

PubMed1999

Anterior sacral meningocele completely occupied by an epidermoid tumor.

A 2-year-old girl presented with an anterior sacral meningocele completely occupied by an epidermoid tumor. Preoperative magnetic resonance imaging had shown the meningocele with contents of the same intensity as cerebrospinal fluid. Surgery via a posterior sacral approach disclosed the tumor beneath an unexpected membrane inside the meningocele. Additionally, the presence of pus inside epidermoid tumor suggested that possible episodes of asymptomatic meningitis or other infection might have occurred before treatment, these being the major complication in anterior sacral meningocele. Therefore, we recommend that surgical treatment should be performed at the earliest possible stage in childhood, once the diagnosis is established, and dural plasty carried out to prevent infectious complications.

Child, Preschool↗

PubMed1999

Sequence analysis of alleles at a microsatellite locus D14S299 (wg1c5) and population genetic comparisons.

In order to increase the discriminating power of DNA analysis in personal identification, we evaluated the forensic utility of the microsatellite locus D14S299 (wg1c5) in the Japanese population and also in the Chinese and Caucasian populations. Twelve different alleles were identified in length by gel electrophoresis with silver staining. The major alleles in Japanese were sequenced and designated as the numbers of the variable repeats (GGAT or GGAA). There were five variable regions and extensive homoplasy was found. However, the allele fragment lengths were in 4 bp increments and no "interalleles" were found. The estimated heterozygosity and the polymorphism information content (PIC) were 0.726 and 0.689, respectively in Japanese. Those in Chinese (0.743 and 0.704) were similar to those in Japanese, while those in Caucasians (0.812 and 0.781) were much higher. After adjacent alleles were combined to yield at least five entries, statistical analysis was performed. The power of discrimination (PD) was 0.887 in Japanese, 0.895 in Chinese and 0.935 in Caucasians and no significant deviations from the Hardy-Weinberg equilibrium were found in the three populations. We retyped all apparently homozygous samples using an alternative pair of flanking primers and found them to be true homozygotes. D14S299 appears to be a useful STR locus for forensic practice.

Asian People↗

PubMed1999

Advantage of intravenous anaesthesia for acute stage surgery of aneurysmal subarachnoid haemorrhage.

To investigate the clinical effects of intravenous anaesthesia on surgical procedure and the outcome in acute stage surgery for aneurysmal subarachnoid haemorrhage (SAH), pre-, intra-, and post-operative factors were analyzed to compare between inhalational (IA, n = 38) and intravenous (IVA, n = 37) anaesthesia. IVA significantly shortened the duration of surgery (p < 0.05) and the duration of hospital stay (p < 0.01). These results suggest that IVA may be more suitable than IA for acute stage surgery of aneurysmal SAH. These effects may be mainly caused by IVA's pharmakokinetics, by effects on intracranial homeostasis and metabolism, and neuroprotective properties.

Acute Disease↗

PubMed1999

Surgical treatment of pineal region tumours through the occipital transtentorial approach: evaluation of the effectiveness of intra-operative micro-endoscopy combined with neuronavigation.

OBJECT: To determine the efficacy and accuracy of surgically-assisted systems including endoscopy combined with neuronavigation in the treatment of pineal region tumours through the occipital transtentorial approach, an evaluation of thirty-one patients undergoing surgery was performed over a 10-year period. METHOD: The study was performed in 2 parts. The surgical approach to the pineal region was the same in the two parts, but in part 2 a smaller craniotomy window was used. Part 1 (from March 1989 to March 1997) included 15 patients who underwent surgical removal of pineal region tumours without using assisted systems; four out of the fifteen patients had surgery-related complications, including seizure and hemianopsia. Part 2 (from April 1997 to February 1999) included 16 patients who underwent surgical treatment by the same surgical team and with assisted systems; all 16 patients had excellent outcomes, with no complications. CONCLUSIONS: Although this study was the first specifically to examine the efficacy of endoscopy combined with neuronavigation in the treatment of pineal region tumours, our findings suggest that these systems are very useful, safe, and accurate in evaluating the primary tumour and surrounding anatomy as well as in determining operative strategy, such as the location and size of the scalp incision, craniotomy, and the extent of surgical removal. Therefore, we conclude that the addition of endoscopy combined with neuronavigation to standard surgical procedures can improve the outcome of surgical treatment of pineal region tumours.

Adolescent↗