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Biomedical subjects

Yoshinobu Maeda

Publications and source records attributed to Yoshinobu Maeda.

At least 19 recordsLinked to original sources
PubMed2025

Efficacy of amivantamab, a bi-specific antibody targeting EGFR and MET, in ALK-rearranged non-small-cell lung cancer cell lines.

BACKGROUND: Anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitors (TKIs) are highly effective in treating ALK-rearranged non-small-cell lung cancer (NSCLC). However, at least 40% of patients develop acquired resistance during treatment. Adaptive or acquired resistance to ALK TKIs could be mediated through epidermal growth factor receptor (EGFR) and mesenchymal-epithelial transition factor (MET) signaling. Sixteen percent of acquired resistance cases are linked to bypass signaling. METHODS: In this study, we evaluated the effects of amivantamab, a bi-specific antibody targeting both EGFR and MET, on ALK-rearranged NSCLC cells. We investigated the effect of amivantamab on the ALK-rearranged NSCLC cell lines H3122, ABC-19, and ABC-11. RESULTS: Combining alectinib with amivantamab resulted in greater inhibition of cell growth inhibition in H3122 and ABC-19 cells compared to alectinib alone, but not in ABC-11 cells. EGFR TKI erlotinib showed similar efficacy in H3122 and ABC-19 cells, whereas MET TKI tepotinib was ineffective in both, suggesting that the efficacy of amivantamab is through EGFR inhibition. Unlike H3122 and ABC-19 cells, ABC-11 cells were resistant to EGFR/MET signaling inhibition. Interestingly, amivantamab enhanced alectinib efficacy against ABC-11 cells in the presence of peripheral blood mononuclear cells (PBMCs), despite showing no effect alone without PBMCs, suggesting action through non-signal inhibitory mechanisms. Finally, we treated alectinib-resistant cellswith alectinib, with or without amivantamab, and found that amivantamab restored the sensitivity of these cells to alectinib. CONCLUSION: The bi-specific antibody amivantamab, which targets EGFR and MET, enhanced the efficacy of alectinib through both signal and non-signal inhibitory mechanisms in ALK-rearranged NSCLC cells.

Humans↗
PubMed2007

Involvement of persistent Na+ current in spike initiation in primary sensory neurons of the rat mesencephalic trigeminal nucleus.

It was recently shown that the persistent Na(+) current (I(NaP)) is generated in the proximal axon in response to somatic depolarization in neocortical pyramidal neurons, although the involvement of I(NaP) in spike initiation is still unclear. Here we show a potential role of I(NaP) in spike initiation of primary sensory neurons in the mesencephalic trigeminal nucleus (MTN) that display a backpropagation of the spike initiated in the stem axon toward the soma in response to soma depolarization. Riluzole (10 muM) and tetrodotoxin (TTX, 10 nM) caused an activation delay or a stepwise increase in the threshold for evoking soma spikes (S-spikes) without affecting the spike itself. Simultaneous patch-clamp recordings from the soma and axon hillock (AH) revealed that bath application of 50 nM TTX increased the delay in spike activation in response to soma depolarization, leaving the spike-backpropagation time from the AH to soma unchanged. This indicates that the increase in activation delay occurred in the stem axon. Furthermore, under a decreasing intracellular concentration gradient of QX-314 from the soma to AH created by QX-314-containing and QX-314-free patch pipettes, the amplitude and maximum rate of rise (MRR) of AH-spikes decreased with an increase in the activation delay following repetition of current-pulse injections, whereas S-spikes displayed decreases of considerably lesser degree in amplitude and MRR. This suggests that compared to S-spikes, AH-spikes more accurately reflect the attenuation of axonal spike by QX-314, consistent with the nature of spike backpropagation. These observations strongly suggest that low-voltage-activated I(NaP) is involved in spike initiation in the stem axon of MTN neurons.

4-Aminopyridine↗
PubMed2007

Mouthguards: difference in longitudinal dimensional stability between single- and double-laminated fabrication techniques.

Though the use of mouthguards (MGs) has increased with the increase in sporting activities, little is known about the influence of their fabrication methods on longitudinal dimensional stability. The objective of this study was to compare the difference in the longitudinal dimensional stability between single and laminated MGs. Single-layer MGs were made from a 4.0 mm thick ethylene vinyl acetate (EVA) sheet and laminated MGs were made from two 2.0 mm thick sheets of EVA. MGs were kept in a 37 degrees C water bath for 60 h, equivalent to the time period of 3-months inter-oral use. MG deformation was analyzed by measuring designated points on the MG border using a profile projector (J-12, Nikon Inc., Tokyo, Japan) before and after the water immersion. A finite-element model was also created to examine the time course of stress accumulation during the sheet forming process using Finite Element software. Longitudinal deformation was smaller in the laminated MGs than in the single-layer MGs in the anterior area (P < 0.05). Finite element method (FEM) analysis also showed the largest stress accumulation in the anterior incisal area where deformations were mainly observed. Laminated double layer MGs have advantages over single-layer MGs in terms of longitudinal stability due to lower stress accumulation during the fabrication process.

Equipment Design↗
PubMed2006

Chronic lymphoproliferative disorder with regulatory T-cell phenotype.

We report a case of T-cell chronic lymphoproliferative disorder (CLPD) that shows neither features of T-cell prolymphocytic leukemia nor disease progression for more than 34 months. Flow cytometric analyses of the lymphocytes revealed high expression of CD4 and CD25. Up-regulation of Foxp3, a master regulatory gene for developmental differentiation of regulatory T cells (Treg), was confirmed at mRNA and protein levels. To our knowledge, this is the first case of extremely indolent CLPD with Treg phenotype.

Aged↗
PubMed2006

Composite resin root coping with a keeper for magnetic attachment for replacing the missing coronal portion of a removable partial denture abutment.

Numerous methods for replacing missing removable partial denture abutments have been introduced, however, most of them are time consuming and require several visits to complete the procedure. Since magnetic attachments can provide support and bracing as well as retention for overdenture abutments, the remaining tooth root structure can be used to support the coping with the keeper. Through the use of composite resin and adhesive material, improved retention of the keeper to the root may be achieved, along with improved esthetics. This article describes a method for replacing the missing abutment of a removable partial denture with a magnetic attachment, and a composite resin coping with a keeper.

Composite Resins↗
PubMed2006

Anterior palatal mouthguard margin location and its effect on shock-absorbing capability.

The purpose of this study was to evaluate the influence of a mouthguard's (MGs) anterior palatal margin location on its shock absorbing capability. A simulation study was conducted on a maxillary phantom model with maxillary teeth, bone, and soft tissue. Miniature strain gauges were attached to the labial and palatal surfaces of the right central incisor as well as the bone surface on the palatal side. MGs were made with ethylene vinyl acetate sheets, with thickness of 2.0, 3.0, and 4.0 mm, using a pressure-forming machine. The locations of the anterior palatal MG margins were set at 4.0, 2.0, and 0 mm from the cervical margin in three experimental configurations. The control situation was without a MG. A calibrated 7N of shock was applied to the middle portions of the labial and palatal surfaces of the central incisor. The amount of tooth deflection was evaluated. The results were analyzed with one-way anova accompanied by the Scheffe's test and multiple regression analysis (P<0.05), designating the strain as the dependent value. The results indicated that the thickness rather than the location of the anterior palatal margin of the MG has a significant influence on the reduction of tooth deflection against a horizontal blow.

Adult↗
PubMed2006

Single-dose daily infusion of cyclosporine for prevention of Graft-versus-host disease after allogeneic bone marrow transplantation from HLA allele-matched, unrelated donors.

Peak blood concentration of cyclosporine (CsA) in renal transplantation patients was recently reported to be associated with clinical efficacy. We therefore evaluated the toxicity and efficacy of a regimen of once-daily infusion of CsA plus a short course of methotrexate as prophylaxis of graft-versus-host disease (GVHD) after allogeneic bone marrow transplantation from an HLA allele-matched, unrelated donor. Nineteen patients with hematologic malignancies received CsA, 3 mg/kg per day, as a 4-hour intravenous (IV) infusion from day -1. After engraftment, patients received CsA orally at twice the IV dose. The CsA dose was adjusted to maintain the blood trough level between 150 and 200 ng/mL. Methotrexate was administered IV at doses of 10 mg/m(2) on day 1 and 7 mg/m(2) on days 3, 6, and 11. Bone marrow engraftment occurred in all patients. Grade 1 and grade 2 GVHD occurred in 6 (31.6%) and 7 (36.8%) of the 19 patients, respectively. No patient had grade 3 or 4 GVHD. Acute nephrotoxicity developed in 1 (5.3%) of the 19 patients, and hypertension developed in 3 (15.8%) of the 19 patients. We evaluated the pharmacokinetics of 4-hour CsA infusion in 10 patients. The mean trough concentration, mean peak concentration, mean time to peak concentration, and area under the curve (24 hours) were 161 +/- 43 ng/mL, 1498 +/- 387 ng/mL, 3.2 +/- 1.0 hours, and 10,848 +/- 1,991 ng +/- h/mL, respectively. This regimen was well tolerated and did not enhance the risk of severe GVHD in patients undergoing allogeneic bone marrow transplantation from an HLA allele-matched, unrelated donor.

Adolescent↗
PubMed2006

[Stress releasing effect of tissue conditioning materials for interim dentures after implant installation].

PURPOSE: The main objective of this study was to examine the influence of the thickness and its longitudinal change within the limited denture space on the stress releasing effect for installed implants during the healing period of a two-stage procedure. METHODS: As for the tissue conditioning material, Tissue Conditioner (Shofu, Kyoto, Japan) with the designated powder liquid ratio was used. The force transmitted to the implant with the material 5 min after the mixing was measured by a miniature pressure sensor in the position of the implant head (Kyowa, Tokyo, Japan). Measurements were repeated with the material preserved in the water for one and two weeks. Load of 2 kg was applied with a 3-mm diameter round tip using a static loading machine for 2 min to the center of the flat type denture model. The model consisted of denture, mucosa, tissue conditioning material and implant where the first three variables were changed as in the oral cavity. Influence of thickness of each variable was examined longitudinally. RESULTS: Force measured with any thickness of tissue conditioning material was smaller than that without the material. The stress releasing effect did not change with change of the longitudinal material property up to two weeks. CONCLUSIONS: Within the limitations of our study, it was suggested that the stress releasing effect of the tissue conditioning material for the installed implant was not influenced by the thickness or change of longitudinal property.

Dental Implants↗
PubMed2005

A crucial role for antigen-presenting cells and alloantigen expression in graft-versus-leukemia responses.

Graft-versus-leukemia (GVL) response after allogeneic bone marrow transplantation (BMT) represents one of the most potent forms of immunotherapy against malignant diseases. Antigen-presenting cells (APCs) are crucial for the induction of graft-versus-host disease (GVHD), the most serious complication of allogeneic BMT, but their role in GVL responses is unclear. Using a series of clinically relevant mouse GVL tumor models, we found that APCs and alloantigen expression on tumors are crucial for GVL. Moreover, APCs of host origin predominated in GVL responses although donor APCs contributed as the acuity of tumor burden decreased.

Animals↗
PubMed2005

Critical role of host gammadelta T cells in experimental acute graft-versus-host disease.

Gammadelta T cells localize to target tissues of graft-versus-host disease (GVHD) and therefore we investigated the role of host gammadelta T cells in the pathogenesis of acute GVHD in several well-characterized allogeneic bone marrow transplantation (BMT) models. Depletion of host gammadelta T cells in wild-type (wt) B6 recipients by administration of anti-T-cell receptor (TCR) gammadelta monoclonal antibody reduced GVHD, and gammadelta T-cell-deficient (gammadelta-/-) BM transplant recipients experienced markedly improved survival compared with normal controls (63% vs 10%, P < .001). gammadelta T cells were responsible for this difference because reconstitution of gammadelta-/- recipients with gammadelta T cells restored GVHD mortality. gammadelta-/- recipients showed decreased serum levels of tumor necrosis factor alpha (TNF-alpha), less GVHD histopathologic damage, and reduced donor T-cell expansion. Mechanistic analysis of this phenomenon demonstrated that dendritic cells (DCs) from gammadelta-/- recipients exhibited less allostimulatory capacity compared to wt DCs after irradiation. Normal DCs derived from BM caused greater allogeneic T-cell proliferation when cocultured with gammadelta T cells than DCs cocultured with medium alone. This enhancement did not depend on interferon gamma (IFN-gamma), TNF-alpha, or CD40 ligand but did depend on cell-to-cell contact. These data demonstrated that the host gammadelta T cells exacerbate GVHD by enhancing the allostimulatory capacity of host antigen-presenting cells.

Acute Disease↗
PubMed2005

Primary tracheal lymphoma: case report and literature review.

We describe a 20-year-old Japanese woman with anaplastic large cell lymphoma in whom primary tracheal involvement was associated with life-threatening airway obstruction. After debulking surgery, the patient was successfully treated with chemotherapy and radiotherapy. A total of 28 cases of primary tracheal lymphoma were reviewed. Common clinical features included predominance of localized disease, respiratory symptoms resembling acute asthma, absence of hemoptysis, and rapid progression of tracheal stenosis. Various histological subtypes of primary tracheal lymphoma exist and are likely to determine prognosis.

Asthma↗
PubMed2005

Are mouthguards necessary for basketball?

This literature review evaluates the significance of dental injuries and their relationship to a specific sport--basketball. Many studies have been published on individual sports or groups of sports, but most pertain to specific age groups or levels of competition. Research suggests that many sports that do not require mouthguards should encourage male and female participants to use orofacial protectors. Athletes, coaches, athletic directors, athletic trainers, parents, and members of the dental community should be aware of how individuals who participate in sporting activities are at risk for dental trauma. Any sport where the potential for dental trauma can exist, such as basketball, soccer, or wrestling, should consider utilizing mouthguards to protect the competitors. The establishment of mouthguard programs for athletes of all ages and genders who participate in basketball may help to reduce the incidence of dental trauma.

Basketball↗
PubMed2004

Both perforin and Fas ligand are required for the regulation of alloreactive CD8+ T cells during acute graft-versus-host disease.

Fas ligand (FasL) and perforin pathways not only are the major mechanisms of T cell-mediated cytotoxicity but also are involved in homeostatic regulation of these T cells. In the present study, we tested whether CD8+ donor T cells that are deficient in both perforin and FasL (cytotoxic double deficient [cdd]) could induce graft-versus-host disease (GVHD) in a major histocompatibility complex class I-mismatched lethally irradiated murine model. Interestingly, recipients of cdd CD8+ T cells demonstrated significantly greater serum levels of interferon gamma and tumor necrosis factor alpha and histopathologic damage from GVHD than wild-type (wt) T cells on day 30 after allogeneic bone marrow transplantation (P<.05). Wt and either perforin-deficient or FasL-deficient CD8+ T cells expanded early after transplantation followed by a contraction phase in which the majority of expanded CD8+ T cells were eliminated. In contrast, cdd CD8+ T cells exhibited prolonged expansion and reduced apoptosis to alloantigen stimulation in vivo and in vitro. Together these results suggest that donor cdd CD8+ T cells expand continuously and cause lethal GVHD, and that both perforin and FasL are required for the contraction of allo-reactive CD8+ T cells.

Acute Disease↗
PubMed2004

Paradoxical effects of interleukin-18 on the severity of acute graft-versus-host disease mediated by CD4+ and CD8+ T-cell subsets after experimental allogeneic bone marrow transplantation.

Administration of exogenous interleukin-18 (IL-18) regulates experimental acute graft-versus-host disease (GVHD) in a Fas-dependent manner when donor CD4(+) T cells are required for mortality after experimental allogeneic bone marrow transplantation (BMT). However, CD4(+) and CD8(+) T cells can induce acute GVHD after clinical allogeneic BMT, and the role of IL-18 in CD8(+)-mediated acute GVHD is unknown. We, therefore, determined the role of IL-18 in GVHD mediated by CD4(+) or CD8(+) T cells across major histocompatibility complex (MHC) class II- and class I-disparate allogeneic BMT, respectively. Administering IL-18 significantly increased survival in CD4(+)-mediated GVHD but reduced survival in CD8(+)-mediated GVHD. This increase in deaths was associated with significantly greater clinical, biochemical, and histopathologic parameters of GVHD damage and was independent of Fas expression on donor T cells. Administering IL-18 significantly enhanced allospecific cytotoxic function and expansion of CD8(+) cells. Endogenous IL-18 was critical to GVHD mediated by CD8(+) donor T cells because IL-18 receptor-deficient donors caused significantly less GVHD but exacerbated CD4(+)-mediated, GVHD-related death. Furthermore, administering anti-IL-18 monoclonal antibody significantly reduced CD8(+)-mediated, GVHD-related death. Together these findings demonstrate that IL-18 has paradoxical effects on CD4(+) and CD8(+) cell-mediated GVHD.

Acute Disease↗
PubMed2004

Host dendritic cells alone are sufficient to initiate acute graft-versus-host disease.

Alloantigen expression on host APCs is essential to initiate graft-vs-host disease (GVHD); however, critical APC subset remains to be elucidated. We compared the ability of dendritic cells (DCs) and B cells to initiate acute GVHD by an add-back study of MHC class II-expressing APCs (II(+/+)) into MHC class II-deficient (II(-/-)) mice that were resistant to CD4-dependent GVHD. Injection of host-derived, but not donor-derived, II(+/+) DCs or host-derived II(+/+) B cells, was sufficient to break GVHD resistance of II(-/-) mice and induced lethal acute GVHD. By contrast, host-derived II(+/+) B cells, both naive and LPS stimulated, failed to induce activation or tolerance of donor CD4(+) T cells. Similarly, in a model of CD8-dependent GVHD across MHC class I mismatch injection of allogeneic DCs, but not B cells, induced robust proliferation of donor CD8(+) T cells and broke GVHD resistance of chimeric recipients in which APCs were syngeneic to donors. These results demonstrate that host-derived DCs are critical in priming donor CD4(+) and CD8(+) T cells to cause GVHD, and selective targeting of host DCs may be a promising strategy to prevent GVHD.

Acute Disease↗
PubMed2004

Histone deacetylase inhibitor suberoylanilide hydroxamic acid reduces acute graft-versus-host disease and preserves graft-versus-leukemia effect.

Acute graft-versus-host disease (GVHD) and leukemic relapse are the two major obstacles to successful outcomes after allogeneic bone marrow transplantation (BMT), an effective therapy for hematological malignancies. Several studies have demonstrated that the dysregulation of proinflammatory cytokines and the loss of gastrointestinal tract integrity contribute to GVHD, whereas the donor cytotoxic responses are critical for graft-versus-leukemia (GVL) preservation. Suberoylanilide hydroxamic acid (SAHA) is currently in clinical trials as an antitumor agent; it inhibits the activity of histone deacetylases and at low doses exhibits antiinflammatory effects by reducing the production of proinflammatory cytokines. Using two well characterized mouse models of BMT, we have studied the effects of SAHA on GVHD severity and GVL activity. Administration of SAHA from day +3 to day +7 after BMT reduced serum levels of the proinflammatory cytokines and decreased intestinal histopathology, clinical severity, and mortality from acute GVHD compared with vehicle-treated animals. However, SAHA had no effect on donor T cell proliferative and cytotoxic responses to host antigens in vivo or in vitro. When mice received lethal doses of tumor cells at the time of BMT, administration of SAHA did not impair GVL activity and resulted in significantly improved leukemia-free survival by using two different tumor and donor/recipient combinations. These findings reveal a critical role for histone deacetylase inhibition in the proinflammatory events contributing to GVHD and suggest that this class of pharmacologic agents may provide a strategy to reduce GVHD while preserving cytotoxic T cell responses to host antigens and maintaining beneficial GVL effects.

Animals↗