[Molecular medicine of hearing loss].
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Aging↗
Biomedical subjects
K Kitamura
Publications and source records attributed to K Kitamura.
[Cell cycle checkpoint mechanism enforced by kinases hChk1 and hCds1].
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Animals↗
Postoperative vestibular-evoked myogenic potentials in cases with vestibular schwannomas.
Although still the subject of discussion, vestibular-evoked myogenic potentials (VEMPs) have been considered to reflect the function of the saccular and, more recently, the cochlear tracts. To accurately determine the precise afferent pathway carrying VEMPs, we studied the outcomes of VEMPs and other examinations in patients with unilateral vestibular schwannomas. Eleven patients with unilateral vestibular schwannomas resected using a middle cranial fossa approach were included in the study. Patients underwent pure-tone threshold audiometry, caloric tests and analysis of auditory brainstem responses (ABRs) and VEMPs pre- and postoperatively. The results were compared with those obtained in patients with intact superior or inferior vestibular and cochlear nerves. Among the 11 patients studied, 4 retained their VEMPs postoperatively. Three of the 10 patients with inferior vestibular schwannomas exhibited normal VEMPs, preserved hearing levels (20 dB HL) and anatomically intact superior vestibular nerves. In all of these cases, ABRs more closely correlated with VEMPs than with caloric responses. In one of the cases with inferior vestibular schwannomas, VEMPs were preserved postoperatively and VEMP latencies were shortened, which indicates the preoperative presence of a conduction block in either the cochlear or superior vestibular nerve. VEMPs may be conducted in both the superior vestibular and cochlear nerves, as well as in the inferior vestibular nerve. Thus, evaluation of saccular nerve function should be performed carefully, especially in cases where hearing is preserved. It appears that cochlear conduction may proceed along two pathways, one direct and the other via the brainstem, but this remains to be verified.
Adult↗
[Progression from adenocarcinoma to small cell carcinoma of the prostate during endocrinotherapy: a case report].
A 72-year-old man had undergone surgical castration for metastatic prostate cancer (stage D2, the PSA value was 4,300 ng/ml) in September, 1997. He was well clinically for 16 months with undetected level of PSA. However, he presented with general malaise and gross hematuria in May, 1999. After admission to our hospital his condition rapidly deteriorated and he died one week later with respiratory failure. Autopsy revealed extensive involvement of the prostate and bladder by solid tumor with multiple metastases in lungs, liver, spleen, kidneys and bone. Histological examination revealed pure small cell carcinoma of the prostate.
Adenocarcinoma↗
Management of failed or failing infrainguinal bypasses with distal correctable lesions.
The goal of this study was to assess the management of failed or failing infrainguinal bypasses with distal correctable lesions. A retrospective analysis of 94 procedures was performed for 72 (77%) failed and 22 (23%) failing infrainguinal bypasses with distal correctable lesions in 94 patients. The 94 procedures included 50 (53%) balloon angioplasties and 44 (47%) distal vein graft extensions from the previous graft to the distal artery. Preprocedural thrombolytic therapy was performed in 62 of 94 limbs with a failed graft, and complete thrombolysis was achieved in 30 of 94. The results of thrombolytic therapy (complete or incomplete thrombolysis) or the means of revision procedure (balloon angioplasty or distal vein graft extension) did not affect the patency. Lower patency was observed for women, patients with a secondary bypass, and grafts with multiple episodes of revision. We conclude that the patency of failing infrainguinal bypasses after revision of distal lesions was affected not by means of therapy but by previous vascular procedures, the usual risk factors, and female gender.
Adult↗
[Effect of monoclonal antibody-neocarzinostatin conjugate for gastric cancer with peritoneal dissemination--comparison between early and late administration].
A7-NCS, which is a conjugate of the monoclonal antibody A7 against a human colonic cancer and the anticancer agent neocarzinostatin (NCS), reacts with human gastric cancers at a high rate. The anticancer effect of A7-NCS is stronger than that of free NCS. Nude mice models of peritoneal dissemination were established simply by intra-peritoneal inoculation of the antigen-positive human gastric cancer cell line MKN45. Using these models, the anticancer effect of A7-NCS against the peritoneal dissemination of gastric cancer was examined. The murine peritoneal dissemination models were divided into three groups. The anticancer effect of the group injected intra-peritoneally with A7-NCS 2 days after cancer inoculation was compared with that injected 18 days after inoculation. The anticancer effect in the 18-day group was inferior to that in the 2-day group, but was superior to that in the non-treated group. To get a better result in the 18-day group, which is in the advanced stage of peritoneal dissemination, repeated injection and the dose of A7-NCS should be examined.
Animals↗
Use of an implanted marker and real-time tracking of the marker for the positioning of prostate and bladder cancers.
PURPOSE: A real-time tracking radiotherapy was investigated to assess its usefulness in precise localization and verification of prostate and bladder cancers. METHODS AND MATERIALS: The real-time tracking radiation therapy (RTRT) system consists of implantation of a 2.0-mm gold marker into a clinical target volume (CTV), three-dimensional radiation treatment planning (3DRTP) system, and the use of two sets of diagnostic x-ray television systems in the linear accelerator room, image processing units, and an image display unit. The position of the patient can be corrected by adjusting the actual marker position to the planned marker position, which has been transferred from the 3DRTP and superimposed on the fluoroscopic image on the display unit of the RTRT system. The position of the markers can be visualized during irradiation and after treatment delivery to verify the accuracy of the localization. Ten patients with prostate cancer and 5 patients with bladder cancer were examined using this system for the treatment setup on 91 occasions. RESULTS: After manual setup using skin markers, the median of absolute value of discrepancies between the actual position of the marker and the planned position of the marker for prostate cancer was 3.4 (0.1-8.9) mm, 4.1 (0.2-18.1) mm, and 2.3 (0.0-10.6) mm for the lateral, anteroposterior, and craniocaudal directions, respectively. The 3D median distance between the actual and planned positions of the marker was 6.9 (1.1-18.2) mm for prostate cancer and 6.9 (1.7-18.6) mm for bladder cancer. After relocation using RTRT, the 3D distance between the actual and planned position of the marker was 0.9 +/- 0.9 mm. Median 3D distances between actual positions after treatment delivery and planned positions were 1.6 (0.0-6.3) mm and 2.0 (0.5-8.0) mm during daily radiotherapy for the marker in patients with prostate cancer and bladder cancer, respectively. CONCLUSION: We believe the new positioning system can reduce uncertainty due to setup error and internal organ motion, although further improvement is needed for the system to account for the rotational and elastic changes of the affected tissues.
Humans↗
Physical aspects of a real-time tumor-tracking system for gated radiotherapy.
PURPOSE: To reduce uncertainty due to setup error and organ motion during radiotherapy of tumors in or near the lung, by means of real-time tumor tracking and gating of a linear accelerator. METHODS AND MATERIALS: The real-time tumor-tracking system consists of four sets of diagnostic X-ray television systems (two of which offer an unobstructed view of the patient at any time), an image processor unit, a gating control unit, and an image display unit. The system recognizes the position of a 2.0-mm gold marker in the human body 30 times per second using two X-ray television systems. The marker is inserted in or near the tumor using image guided implantation. The linear accelerator is gated to irradiate the tumor only when the marker is within a given tolerance from its planned coordinates relative to the isocenter. The accuracy of the system and the additional dose due to the diagnostic X-ray were examined in a phantom, and the geometric performance of the system was evaluated in 4 patients. RESULTS: The phantom experiment demonstrated that the geometric accuracy of the tumor-tracking system is better than 1.5 mm for moving targets up to a speed of 40 mm/s. The dose due to the diagnostic X-ray monitoring ranged from 0.01% to 1% of the target dose for a 2.0-Gy irradiation of a chest phantom. In 4 patients with lung cancer, the range of the coordinates of the tumor marker during irradiation was 2.5-5.3 mm, which would have been 9.6-38.4 mm without tracking. CONCLUSION: We successfully implemented and applied a tumor-tracking and gating system. The system significantly improves the accuracy of irradiation of targets in motion at the expense of an acceptable amount of diagnostic X-ray exposure.
Algorithms↗
Identification and characterization of human DNA polymerase beta 2, a DNA polymerase beta -related enzyme.
The BRCA1 COOH terminus (BRCT) motif is present in many nuclear proteins that contribute to cell cycle regulation or DNA repair. Polymerase chain reaction-based screening with degenerate primers targeted to the BRCT motif resulted in the isolation of a human cDNA for a previously unidentified DNA polymerase (designated DNA polymerase beta2) that is closely related to DNA polymerase beta (Pol beta). The predicted Pol beta2 protein contains a BRCT motif in its NH(2)-terminal region; its COOH-terminal region exhibits 33% sequence identity to a corresponding region of human Pol beta. The Pol beta2 gene is expressed in a tissue-specific manner, with transcripts being most abundant in testis. A fusion construct comprising Pol beta2 and green fluorescent protein exhibited a predominantly nuclear localization in transfected HeLa cells. Recombinant human Pol beta2 from insect cells exhibited substantial DNA polymerase activity, but it did not possess terminal deoxyribonucleotidyl transferase activity. A truncated Pol beta2 mutant lacking the BRCT motif retained substantial DNA polymerase activity, whereas a mutant Pol beta2 with two alanine point mutations within the DNA polymerase active site did not. These results indicate that Pol beta2 is a Pol beta-related DNA polymerase with a BRCT motif that is dispensable for its polymerase activity.
Amino Acid Motifs↗
Adrenomedullin receptors in rat cerebral microvessels.
To characterize the sites of action of adrenomedullin (AM) in the cerebral microvasculature, we studied the effect of AM on cyclic AMP (cAMP) level as well as expression of AM and its receptor in the rat cerebral microvessels. The microvessels were prepared from rat cerebral cortex by albumin flotation and glass bead filtration technique. AM and calcitonin gene-related peptide (CGRP) increased cAMP level in the microvessels in a concentration-dependent manner. The effect of AM was more than 100 times more potent than that of CGRP. The accumulation of cAMP by AM was inhibited by AM[22-52], an AM receptor antagonist, but not by CGRP[8-37], a CGRP receptor antagonist, suggesting that AM increased cAMP accumulation by acting on receptors specific to AM. [125I]AM binding to the microvessels was displaced by AM and less potently by AM[22-52]. The displacing potencies of CGRP and CGRP[8-37] were very weak. mRNAs for AM as well as calcitonin-receptor-like receptor and receptor-activity-modifying protein 2 which form a receptor specific to AM, were highly expressed in the microvessels. These results provide biochemical and pharmacological evidence that AM is produced in and acts on the cerebral microvessels in an autocrine/paracrine manner and is involved in regulation of cerebral microcirculation.
Adrenomedullin↗
Visualization of the calcitonin receptor-like receptor and its receptor activity-modifying proteins during internalization and recycling.
Expression of the calcitonin receptor-like receptor (CRLR) and its receptor activity modifying proteins (RAMPs) can produce calcitonin gene-related peptide (CGRP) receptors (CRLR/RAMP1) and adrenomedullin (AM) receptors (CRLR/RAMP2 or -3). A chimera of the CRLR and green fluorescent protein (CRLR-GFP) was used to study receptor localization and trafficking in stably transduced HEK 293 cells, with or without co-transfection of RAMPs. CRLR-GFP failed to generate responses to CGRP or AM without RAMPs. Furthermore, CRLR-GFP was not found in the plasma membrane and its localization was unchanged after agonist exposure. When stably coexpressed with RAMPs, CRLR-GFP appeared on the cell surface and was fully active in intracellular cAMP production and calcium mobilization. Agonist-mediated internalization of CRLR-GFP was observed in RAMP1/CGRP or AM, RAMP2/AM, and RAMP3/AM, which occurred with similar kinetics, indicating the existence of ligand-specific regulation of CRLR internalization by RAMPs. This internalization was strongly inhibited by hypertonic medium (0.45 m sucrose) and paralleled localization of rhodamine-labeled transferrin, suggesting that CRLR endocytosis occurred predominantly through a clathrin-dependent pathway. A significant proportion of CRLR was targeted to lysosomes upon binding of the ligands, and recycling of the internalized CRLR was not efficient. In HEK 293 cells stably expressing CRLR-GFP and Myc-RAMPs, these rhodamine-labeled RAMPs were co-localized with CRLR-GFP in the presence and absence of the ligands. Thus, the CRLR is endocytosed together with RAMPs via clathrin-coated vesicles, and both the internalized molecules are targeted to the degradative pathway.
Calcitonin Receptor-Like Protein↗
Four-dimensional treatment planning and fluoroscopic real-time tumor tracking radiotherapy for moving tumor.
PURPOSE: To achieve precise three-dimensional (3D) conformal radiotherapy for mobile tumors, a new radiotherapy system and its treatment planning system were developed and used for clinical practice. METHODS AND MATERIALS: We developed a linear accelerator synchronized with a fluoroscopic real-time tumor tracking system by which 3D coordinates of a 2.0-mm gold marker in the tumor can be determined every 0.03 second. The 3D relationships between the marker and the tumor at different respiratory phases are evaluated using CT image at each respiratory phase, whereby the optimum phase can be selected to synchronize with irradiation (4D treatment planning). The linac is triggered to irradiate the tumor only when the marker is located within the region of the planned coordinates relative to the isocenter. RESULTS: The coordinates of the marker were detected with an accuracy of +/- 1 mm during radiotherapy in the phantom experiment. The time delay between recognition of the marker position and the start or stop of megavoltage X-ray irradiation was 0.03 second. Fourteen patients with various tumors were treated by conformal radiotherapy with a "tight" planning target volume (PTV) margin. They were surviving without relapse or complications with a median follow-up of 6 months. CONCLUSION: Fluoroscopic real-time tumor tracking radiotherapy following 4D treatment planning was developed and shown to be feasible to improve the accuracy of the radiotherapy for mobile tumors.
Computer Systems↗
Antinociceptive effect of cilnidipine, a novel N-type calcium channel antagonist.
We investigated the antinociceptic effects of cilnidipine, a dihydropyridine derivative which acts on both L- and N-type voltage-dependent calcium channels, in mice. Intrathecally injected cilnidipine showed significant analgesic effect in formalin test. Cilnidipine significantly suppressed N-type currents in dorsal root ganglion (DRG) cells. Our findings apparently support the idea that cilnidipine attenuates synaptic neurotransmission by inhibiting N-type calcium channels in DRG neurons.
Animals↗
Construction, production, and characterization of humanized anti-Lewis Y monoclonal antibody 3S193 for targeted immunotherapy of solid tumors.
The Lewis Y (Ley) antigen is a blood group-related antigen that is expressed in a high proportion of epithelial cancers (including breast, colon, ovary, and lung cancer) and is an attractive target for monoclonal antibody-directed therapy. The murine monoclonal 3S193 (IgG3) was generated in BALB/c mice by immunization with Ley-expressing cells of the MCF-7 breast carcinoma cell-line. The murine 3S193 showed high specificity for Ley in ELISA tests with synthetic Ley and Ley-containing glycoproteins and glycolipids and also reacted strongly in rosetting assays and cytotoxic tests with Ley-expressing cells. We generated a humanized form of the murine 3S193 antibody by linking cDNA sequences encoding the variable region of murine 3S913 with frameworks of the human KOL heavy chain and REI K chain. The genes for the humanized 3S193 monoclonal antibody IgG1 were transfected into mouse myeloma NS0 cells and cloned for the establishment of high antibody-producing colonies. Humanized 3S193 antibody was subsequently produced through in vitro culture and under good manufacturing practice conditions using hollow-fiber bioreactors. The purified humanized 3S193 (hu3S193) was subsequently characterized and validated for use in preliminary immunotherapy investigations. hu3S193 reacted specifically with Ley antigen, with similar avidity to the murine form. hu3S193 demonstrated potent immune effector function, with higher antibody-dependent cell-mediated cytotoxicity than its murine counterpart and potent complement-dependent cytotoxicity (ED50, 1.0 microg/ml). The in vivo immunotherapeutic potential of hu3S193 was assessed in a human breast xenograft model using MCF-7, Ley-positive cells. Six i.v. doses of up to 1 mg of hu3S193 were administered to animals bearing established tumors (120-130 mm3) with no significant effect on tumor growth. In contrast, in an MCF-7 xenograft preventive model, a 1-mg hu3S193 dosage schedule was able to significantly slow tumor growth compared with placebo and isotype-matched control IgG1 antibody. hu3S193 has promise for immunotherapy of Ley-positive tumors and is currently entering Phase I clinical trials.
Amino Acid Sequence↗
Smad7 selectively interferes with different pathways of activin signaling and inhibits erythroid leukemia cell differentiation.
Smad family proteins are essential for transforming growth factor beta (TGF-beta) signal mediation downstream of a heteromeric complex of the type I and type II receptor serine/threonine kinases. A distant family member, Smad7, is expressed in most mammalian tissues and cells and prevents TGF-beta signaling. In this study, we examined the physiologic role of Smad7 in mediating the effects of activin, a member of the TGF-beta superfamily of peptides that functions in a number of processes, including blood-cell development. We report here that Smad7 expression is specifically absent in particular hematopoietic cells that respond to activin by differentiating into the erythroid lineage and that ectopic production of Smad7 causes mouse erythroid leukemia (F5-5) cells to become resistant to activin induction of erythroid differentiation. When coexpressed with type I activin receptor ActR-I or ActR-IB in concert with type II receptor ActR-II, Smad7 efficiently reduced an early transcriptional response mediated by ActR-I but had only a minimal effect on the response mediated by ActR-IB. In the presence of Smad7, overexpression of an activated form of ActR-IB, but not of an activated form of ActR-I, induced F5-5 cells to differentiate. These results suggest that Smad7 selectively interferes with the ActR-I pathway in activin signal transduction. The findings also indicate the existence of a novel activity of Smad7 that inhibits erythroid differentiation by blocking intracellular signaling of activin.
3T3 Cells↗
Single-motor mechanics and models of the myosin motor.
Recent progress in single-molecule detection techniques is remarkable. These techniques have allowed the accurate determination of myosin-head-induced displacements and how mechanical cycles are coupled to ATP hydrolysis, by measuring individual mechanical events and chemical events of actomyosin directly at the single-molecule level. Here we review our recent work in which we have made detailed measurements of myosin step size and mechanochemical coupling, and propose a model of the myosin motor.
Actins↗
Diminished expression of ING1 mRNA and the correlation with p53 expression in breast cancers.
p33(ING1) is a novel candidate tumor suppressor and its overexpression induces growth arrest or apoptosis in different cell lines. These functions of p33(ING1) depend largely on the activity of p53, and p53-dependent activation of the transcription from the p21/WAF1 promoter also requires p33(ING1). We examined the expression of ING1 mRNA in breast cancer cell lines and clinical breast cancer tissues, using quantitative RT-PCR and real time TaqMan technology. In breast cancer cell lines, ING1 mRNA was expressed at almost the same level. However, in a comparison between the cancer and matched normal tissues, a significant decrease in ING1 mRNA expression was found in 17 of 24 (70.8%) breast cancer tissues. We also examined the correlation between ING1 mRNA expression and p53 expression. There was a significant decrease of ING1 mRNA in nine of 15 tumors negative for p53 immunostaining, most of which were considered to have wild type p53. In these tumors, p53 may not function in case of a decreased expression of p33(ING1), and the lack of cell cycle regulation may correlate with the carcinogenesis and tumor progression.
Breast Neoplasms↗
Analyses of segment-specific expression of alkaline phosphatase activity in the mesoderm of the oligochaete annelid Tubifex: implications for specification of segmental identity.
In the embryos of the oligochaete annelid Tubifex, segments VII and VIII specifically express mesodermal alkaline phophatase (ALP) activity in the ventrolateral region. In this study, we examined whether this segment-specific expression of ALP activity depends on external cues. Cell lineage analyses show that the ALP-expressing cells originate from M teloblasts. Furthermore, a set of teloblast-ablation experiments demonstrated that the seventh and eighth primary m blast cells (m7 and m8) produced from M teloblasts give rise to ALP-expressing cells in segments VII and VIII, respectively, and that primary m blast cells other than m7 and m8 lack the ability to generate ALP-expressing progeny cells. The results of another set of blastomere-ablation experiments suggest that ALP-expressing cells emerge independently of interactions with surrounding tissues. Teloblast-transplantation experiments demonstrated that m8 can generate ALP-expressing cells in an ectopical position, suggesting that it is unlikely that ALP activity emerges in response to the positional cues residing in the embryo. These results suggest that m7 and m8 are exclusively specified as precursors of ALP-expressing cells at the time of their birth from M teloblasts. We propose that segmental identities in primary m blast cells of the Tubifex embryo are determined according to the genealogical position in the M lineage and that the M teloblast possesses a developmental program through which the sequence of blast cell identities is determined.
Alkaline Phosphatase↗