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Gen Yamada

Publications and source records attributed to Gen Yamada.

At least 37 records · Page 2Linked to original sources
PubMed2005

Subepithelial microvasculature in large airways observed by high-magnification bronchovideoscope.

BACKGROUND: The bronchial vasculature serves important functions and is modified in a variety of pulmonary and airway diseases. The remarkable ability of the bronchial vasculature to undergo remodeling has implications for disease pathogenesis. However, there is very little information on normal bronchial circulation. OBJECTIVES: The aim of this study was to obtain information on bronchial microvessels in large airways using a high-magnification bronchovideoscope. METHODS AND PATIENTS: Recently, we developed a high-magnification bronchovideoscope (XBF-200HM3 [side-viewing type]) in cooperation with Olympus Medical Systems. This bronchovideoscope can provide information on the bronchial mucosa with a maximum magnification of 110 times. Between August 2000 and July 2004, 26 patients without abnormalities in the large airways were enrolled into this study. Patients underwent conventional bronchoscopy and subsequent bronchoscopy with the high-magnification bronchovideoscope. After the bronchoscopic examination, we calculated the vessel area ratios and hemoglobin indexes of images made with the high-magnification bronchovideoscope by using appropriate software. In addition, we compared the findings obtained with the high-magnification bronchovideoscope of the 26 subjects with microscopic findings of autopsied tracheas of two patients without abnormalities. RESULTS: Many ramifying subepithelial microvessels of large airways were mainly observed in intercartilage and membranous portions, whereas only a few microvessels were seen in cartilage portions. Histologically, these subepithelial microvessels were thought to be distributed within approximately 800 and 500 microm beneath the surface of the intercartilage portions and membranous portions, respectively. Vessel area ratios of the intercartilage portions were significantly higher than those of the cartilage and membranous portions. The hemoglobin indexes of the intercartilage portions were significantly higher than those of the cartilage and membranous portions, and these indexes were also significantly higher in the membranous portion than in the cartilage portion. CONCLUSIONS: A dense concentration of subepithelial microvessels was mainly observed in the intercartilage portion, indicating an increase in submucosal circulation. This high-magnification bronchovideoscope is a useful tool for observing and evaluating the subepithelial microvessels in large airways.

Adult↗
PubMed2005

The morphological and histological characters of the male external genitalia of the house musk shrew, Suncus murinus.

External genitalia are the reproductive organs necessary for efficient copulation and internal fertilization in various mammalian species. Their morphogeneses display significant morphological and developmental differences among species. The house musk shrew, Suncus murinus (hereafter described as suncus) is a species of the order Insectivora, which has been considered as primitive and one of the earliest eutheria phylogenetically. Comparative anatomical analyses of phylogenetically different mammals will contribute to the better understanding of morphological diversity of external genitalia. This study performed various anatomical and histological analyses concerning the organization of the external genitalia of male suncus. It was shown that the external genitalia of suncus possessed a muscular structure, which we proposed as musculus ischiocavernosus dorsalis of suncus. The musculus ischiocavernosus dorsalis is originated from the inner surface of the tuber ischiadicum and was allocated adjacent to the corpus cavernosum penis. In addition, a pair of alpha-smooth muscle actin positive muscles was located bilaterally to the urethra. This unique morphology of the external genitalia of suncus males may provide a unique model system to investigate genital morphogenesis.

Anatomy, Comparative↗
PubMed2004

Androgen dependent development of a modified anal fin, gonopodium, as a model to understand the mechanism of secondary sexual character expression in vertebrates.

Male external genitalia show structural variations among species. Androgenic hormones are essential for the morphological specification of male type copulatory organs, while little is known about the developmental mechanisms of such secondary sexual characters. Western mosquitofish Gambusia affinis may offer a clue to the sexual differentiation researches, because they show a prominent masculine sexual character for appendage development, anal fin to gonopodium (GP) transition, and its formation could be induced in early juvenile fry by exogenously supplied androgens. We show that GP development is promoted by androgen dependent augmentation of sonic hedgehog (Shh) expression. Two AR cDNAs were cloned and identified as ARalpha and ARbeta from western mosquitofish. Both ARs were predominantly expressed in the distal region of outgrowing anal fin rays. Exposure of fry to androgen caused anal fin outgrowth concomitant with the Shh induction in the distal anal fin ray epithelium. When AR signaling was inhibited by its antagonist flutamide in fry, the initial induction of the Shh was suppressed accompanying retarded anal fin outgrowth. Similar suppression of anal fin outgrowth was induced by treatment with cyclopamine, an inhibitor of Shh signaling. These observations indicate that androgen dependent Shh expression is required for anal fin outgrowth leading to the formation of a genital appendage, the GP in teleost fishes. Androgen-induced GP formation may provide insights into the expression mechanism regulating the specification of sexual features in vertebrates.

Amino Acid Sequence↗
PubMed2004

Regulation of external genitalia development by concerted actions of FGF ligands and FGF receptors.

Members of the fibroblast growth factor (FGF) family play diverse roles during the development and patterning of various organs. In human and mice, 22 FGFs and four receptors derived from several splice variants are present. Redundant expression and function of FGF genes in organogenesis have been reported, but their roles in embryonic external genitalia, genital tubercle (GT), development have not been studied in detail. To address the role of FGF during external genitalia development, we have analyzed the expression of FGF genes (Fgf8, 9, 10) and receptor genes (Fgfr1, r2IIIb, r2IIIc) in GT of mice. Furthermore, Fgf10 and Fgfr2IIIb mutant mice were analyzed to elucidate their roles in embryonic external genitalia development. Fgfr2IIIb was expressed in urethral plate epithelium during GT development. Fgfr2IIIb mutant mice display urethral dysmorphogenesis. Marker gene analysis for urethral plate and bilateral mesenchymal formation suggests the existence of epithelial-mesenchymal interaction during urethral morphogenesis. Therefore, FGF10/FGFR2IIIb signals seem to constitute a developmental cascade for such morphogenesis.

Animals↗
PubMed2004

Bapx1 regulates patterning in the middle ear: altered regulatory role in the transition from the proximal jaw during vertebrate evolution.

The middle ear apparatus is composed of three endochondrial ossicles (the stapes, incus and malleus) and two membranous bones, the tympanic ring and the gonium, which act as structural components to anchor the ossicles to the skull. Except for the stapes, these skeletal elements are unique to mammals and are derived from the first and second branchial arches. We show that, in combination with goosecoid (Gsc), the Bapx1 gene defines the structural components of the murine middle ear. During embryogenesis, Bapx1 is expressed in a discrete domain within the mandibular component of the first branchial arch and later in the primordia of middle ear-associated bones, the gonium and tympanic ring. Consistent with the expression pattern of Bapx1, mouse embryos deficient for Bapx1 lack a gonium and display hypoplasia of the anterior end of the tympanic ring. At E10.5, expression of Bapx1 partially overlaps that of Gsc and although Gsc is required for development of the entire tympanic ring, the role of Bapx1 is restricted to the specification of the gonium and the anterior tympanic ring. Thus, simple overlapping expression of these two genes appears to account for the patterning of the elements that compose the structural components of the middle ear and suggests that they act in concert. In addition, Bapx1 is expressed both within and surrounding the incus and the malleus. Examination of the malleus shows that the width, but not the length, of this ossicle is decreased in the mutant mice. In non-mammalian jawed vertebrates, the bones homologous to the mammalian middle ear ossicles compose the proximal jaw bones that form the jaw articulation (primary jaw joint). In fish, Bapx1 is responsible for the formation of the joint between the quadrate and articular (homologues of the malleus and incus, respectively) enabling an evolutionary comparison of the role of a regulatory gene in the transition of the proximal jawbones to middle ear ossicles. Contrary to expectations, murine Bapx1 does not affect the articulation of the malleus and incus. We show that this change in role of Bapx1 following the transition to the mammalian ossicle configuration is not due to a change in expression pattern but results from an inability to regulate Gdf5 and Gdf6, two genes predicted to be essential in joint formation.

Animals↗
PubMed2004

Expression of uteroglobin in normal and carcinogenic endometrium and influence of hormone replacement therapy.

Uteroglobin, first reported in 1968 as a steroid secreted in rabbit uterine fluid during early pregnancy, is a progesterone-regulated and progesterone-binding protein. There is evidence that indicates that uteroglobin is inversely correlated to neoplastic growth but its role to endometrial carcinogenesis is not known. Therefore we analyzed the expression of uteroglobin in 13 normal endometrium, 19 hyperplasia and 21 endometrial carcinoma samples and the relation to estrogen receptor-alpha (ER-alpha) and progesterone receptor (PR) by immunohistochemistry and Western blotting. We also analyzed the expression of uteroglobin in 15 menopausal women who received hormone replacement therapy (HRT). The expression of uteroglobin was higher during the secretory phase than in the proliferative phase; however, it was detected in endometrial hyperplasia as weakly as in the proliferative phase and decreased according to the loss of differentiation in endometrial carcinoma. The results were basically in accord with those for PR; however, the expression of uteroglobin was weak, though PR was most detected in endometrial hyperplasia. In menopausal endometrium, the group treated with estrogen plus progesterone exhibited higher expression of uteroglobin than the group treated only with estrogen. The evidence suggests that uteroglobin expression is regulated by progesterone in the normal endometrium but that the regulation by PR is lost in endometrial hyperplasia and carcinoma according to acquirement of tumorigenesis and that estrogen plus progesterone therapy reduces the risk for endometrial carcinoma by restoring uteroglobin.

Blotting, Western↗
PubMed2004

Regeneration of injured intestinal mucosa is impaired in hepatocyte growth factor activator-deficient mice.

BACKGROUND AND AIMS: Hepatocyte growth factor activator (HGFA) is a serum proteinase that specifically converts an inactive single-chain form of hepatocyte growth factor (HGF) into an active 2-chain form. HGFA is produced in its precursor form and then activated in injured tissues. To address the precise role of HGFA and to investigate the mechanisms of HGF activation in injured tissues, we generated mice deficient in HGFA. METHODS: HGFA-deficient mice were generated using targeted gene disruption. The regenerating process of intestinal mucosa damaged by oral administration of dextran sodium sulfate (DSS) or by rectal administration of acetic acid was examined in both HGFA-deficient and control mice. HGF processing activity was analyzed using Western blotting and an HGF activation assay. RESULTS: Homozygous mutant mice were viable and fertile without obvious abnormalities. When mice were treated with 3% DSS in drinking water for 6 days followed by distilled water without DSS, 72% of HGFA-deficient mice died through day 12 while 75% of control mice survived injury. Similar results were also observed in the acetic acid-induced intestinal injury; the survival rate was 36.6% in HGFA-deficient mice and 84.2% in control mice. In HGFA-deficient mice, the injured mucosa was not sufficiently covered by regenerated epithelium and the activation of HGF was impaired in the injured colon. CONCLUSIONS: These results indicate that HGFA is required for repair of injured intestinal mucosa but is not essential for normal development during embryogenesis or after birth.

Animals↗
PubMed2004

Acute lung injury as an adverse event of gefitinib.

Gefitinib, a selective epidermal growth factor receptor tyrosine kinase inhibitor, is an effective treatment for patients with non-small cell lung cancer (NSCLC). Some investigators have recently reported several patients complicated by acute lung injury after the initiation of gefitinib administration. In this report, we investigated the efficacy and adverse events during treatment with gefitinib. The subjects of this study were all of the 110 patients with NSCLC who were treated in our hospital and its eight branch hospitals. Patients received gefitinib at a dose of 250 mg once daily. The response rate was 30%. The frequently reported adverse events were skin disorders, gastrointestinal disturbances, liver dysfunction and acute lung injury. Five of the 12 patients who were considered to have suffered acute lung injury died of progressive respiratory failure. Of the nine patients who had pulmonary fibrosis before use of gefitinib, five developed acute lung injury during the treatment. Sera from three of the 12 patients were evaluated and all three showed increases of surfactant protein (SP)-A, SP-D and KL-6. We conclude that gefitinib was clinically useful. However, several patients suffered acute lung injury which could have been caused by gefitinib. A detection system including SP-A, SP-D and KL-6 as prime candidates as markers should be established as promptly as possible. Clinicians should be aware that treatment of NSCLC with gefitinib involves the risk of acute lung injury and therefore careful consideration should be given before deciding whether or not gefitinib is indicated for treatment. Further study is necessary to elucidate the mechanism of acute lung injury by gefitinib.

Adult↗
PubMed2004

Peripheral primitive neuroectodermal tumor of the chest wall of a 69-year-old man.

We report a case of peripheral primitive neuroectodermal tumor (pPNET), which belongs to the pPNET/Ewing's sarcoma family, arising in the chest wall of a 69-year-old man. He had high levels of serum neuron-specific enolase and pro-gastrin-releasing peptide, which are believed to be useful diagnostic blood markers for small cell lung carcinoma (SCLC). Microscopically, the tumor was composed of solid nests and sheets of monotous, primitive, small round cells with a few rosettes, making it difficult to distinguish from SCLC. Immunohistochemically, the tumor cells showed intense cell membranous immunoreactivity for MIC2 protein (CD99). EWS/FLI-1 chimeric mRNA that originated from the characteristic t(11;22)(q24;q12) chromosomal translocation was detected by RT-PCR and nucleotide sequence analysis. These results confirmed the diagnostic validity of the present tumor being a pPNET, thus raising the possibility that in the past, pPNETs which have arisen in the chest have been mistakenly diagnosed as SCLC.

Aged↗
PubMed2004

[Two younger male patients with rapidly progressing pulmonary pleomorphic carcinoma].

We report 2 cases of pulmonary pleomorphic carcinoma. The patient in case 1 was a 44-year-old man who was admitted to our hospital complaining of dry cough and dyspnea on exertion. Chest radiography and CT showed a huge tumor with left pleural effusion. Percutaneous biopsy suggested malignancy. As distant metastasis was not found and as cytological examination of pleural effusion gave a result of class II, we attempted to perform left pneumonectomy. However, we performed partial resection of the tumor because it had invaded the aorta, pulmonary artery, pericardium and pleura. The pathological diagnosis was pleomorphic carcinoma, p-T4 N2 M0. After the operation, we performed systemic chemotherapy, including cisplatin and irinotecanm with little effect (PD). The patient died of progression of the tumor. Case 2 was a 34-year-old man who was admitted to our hospital complaining of fever and general malaise. Chest radiography and CT showed a tumor in the left upper lobe. As no distant metastasis was found, we tried left upper lobectomy. However, we performed left upper segmentectomy and lymph node dissection because of invasion of the aorta and the chest wall, and because of hypersegmentation of the left upper lobe. Pathological diagnosis was pleomorphic carcinoma, p-T4 N0 M0. After the operation, the mediastinum was subjected to radiation therapy. However, a metastatic tumor was found in the pelvis after this radiation was given. We performed systemic chemotherapy with substances including cisplatin, gemcitabine and vinorelbine, but with little effect (PD). The patient died of peritonitis and pleuritis due to the recurrence and progression of the tumor. Both cases had rapidly growing neoplasms showing little sensitivity to chemotherapy or radiotherapy. Pulmonary pleomorphic carcinoma is suggested to be type of lung cancer with a poor prognosis when the tumor is not resected in the early stages.

Adenocarcinoma↗
PubMed2004

[A case of pyogenic spondylitis mimicking a spinal invasion of lung cancer].

A 58-year old man was admitted to our hospital complaining of right back pain, fever, abdominal fullness and epigastralgia. Chest CT revealed a mass shadow in the right S6 together with destruction of the thoracic vertebrae. These findings suggested lung cancer and its spinal invasion. A transbronchial lung biopsy specimen showed inflammatory lymphocyte infiltration. MRI T2 image of the spine showed a high intensity at the Th7/8 disc space, suggesting pyogenic spondylitis. After broad-spectrum antibiotics including PAMP/BP and CLDM were administered, both the spinal lesion and the pulmonary lesion improved gradually. The clinical course suggested that the pulmonary inflammatory lesion had spread from pyogenic spondylitis. In our case, the pyogenic spondylitis was mimicking a spinal invasion of lung cancer. In addition, MRI is thought to be useful for diagnosing spinal lesions.

Diagnosis, Differential↗
PubMed2003

Six1 controls patterning of the mouse otic vesicle.

Six1 is a member of the Six family homeobox genes, which function as components of the Pax-Six-Eya-Dach gene network to control organ development. Six1 is expressed in otic vesicles, nasal epithelia, branchial arches/pouches, nephrogenic cords, somites and a limited set of ganglia. In this study, we established Six1-deficient mice and found that development of the inner ear, nose, thymus, kidney and skeletal muscle was severely affected. Six1-deficient embryos were devoid of inner ear structures, including cochlea and vestibule, while their endolymphatic sac was enlarged. The inner ear anomaly began at around E10.5 and Six1 was expressed in the ventral region of the otic vesicle in the wild-type embryos at this stage. In the otic vesicle of Six1-deficient embryos, expressions of Otx1, Otx2, Lfng and Fgf3, which were expressed ventrally in the wild-type otic vesicles, were abolished, while the expression domains of Dlx5, Hmx3, Dach1 and Dach2, which were expressed dorsally in the wild-type otic vesicles, expanded ventrally. Our results indicate that Six1 functions as a key regulator of otic vesicle patterning at early embryogenesis and controls the expression domains of downstream otic genes responsible for respective inner ear structures. In addition, cell proliferation was reduced and apoptotic cell death was enhanced in the ventral region of the otic vesicle, suggesting the involvement of Six1 in cell proliferation and survival. In spite of the similarity of otic phenotypes of Six1- and Shh-deficient mice, expressions of Six1 and Shh were mutually independent.

Animals↗
PubMed2003

Regulation of outgrowth and apoptosis for the terminal appendage: external genitalia development by concerted actions of BMP signaling [corrected].

Extra-corporal fertilization depends on the formation of copulatory organs: the external genitalia. Coordinated growth and differentiation of the genital tubercle (GT), an embryonic anlage of external genitalia, generates a proximodistally elongated structure suitable for copulation, erection, uresis and ejaculation. Despite recent progress in molecular embryology, few attempts have been made to elucidate the molecular developmental processes of external genitalia formation. Bone morphogenetic protein genes (Bmp genes) and their antagonists were spatiotemporally expressed during GT development. Exogenously applied BMP increased apoptosis of GT and inhibited its outgrowth. It has been shown that the distal urethral epithelium (DUE), distal epithelia marked by the Fgf8 expression, may control the initial GT outgrowth. Exogenously applied BMP4 downregulated the expression of Fgf8 and Wnt5a, concomitant with increased apoptosis and decreased cell proliferation of the GT mesenchyme. Furthermore, noggin mutants and Bmpr1a conditional mutant mice displayed hypoplasia and hyperplasia of the external genitalia respectively. noggin mutant mice exhibited downregulation of Wnt5a and Fgf8 expression with decreased cell proliferation. Consistent with such findings, Wnt5a mutant mice displayed GT agenesis with decreased cell proliferation. By contrast, Bmpr1a mutant mice displayed decreased apoptosis and augmented Fgf8 expression in the DUE associated with GT hyperplasia. These results suggest that some of the Bmp genes could negatively affect proximodistally oriented outgrowth of GT with regulatory functions on cell proliferation and apoptosis. The DUE region can be marked only until 14.0 dpc (days post coitum) in mouse development, while GT outgrowth continues thereafter. Possible signaling crosstalk among the whole distal GT regions were also investigated.

Animals↗
PubMed2003

Mice with defects in HB-EGF ectodomain shedding show severe developmental abnormalities.

Heparin-binding EGF-like growth factor (HB-EGF) is first synthesized as a membrane-anchored form (proHB-EGF), and its soluble form (sHB-EGF) is released by ectodomain shedding from proHB-EGF. To examine the significance of proHB-EGF processing in vivo, we generated mutant mice by targeted gene replacement, expressing either an uncleavable form (HBuc) or a transmembrane domain-truncated form (HBdeltatm) of the molecule. HB(uc/uc) mice developed severe heart failure and enlarged heart valves, phenotypes similar to those in proHB-EGF null mice. On the other hand, mice carrying HBdeltatm exhibited severe hyperplasia in both skin and heart. These results indicate that ectodomain shedding of proHB-EGF is essential for HB-EGF function in vivo, and that this process requires strict control.

Animals↗