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T Kagawa

Publications and source records attributed to T Kagawa.

At least 19 recordsLinked to original sources
PubMed2004

Adenocarcinoma arising from a gastric duplication cyst with invasion to the stomach: a case report with literature review.

This report describes a rare case of adenocarcinoma arising from a gastric duplication cyst, with invasion to the stomach wall, in a 40 year old Japanese man. A cystic lesion was found between the stomach and the spleen. The cyst had a well circumscribed smooth muscle layer, corresponding to the muscularis propria of the stomach and the mucosa of the alimentary tract. A well differentiated adenocarcinoma was found within the duplication cyst, invading its serosa. Well differentiated adenocarcinoma was independently found in the fundus of the stomach; the tumour of the cyst was connected by fibrous tissue. Microscopically, there was neither adenocarcinoma in situ nor precancerous lesions, such as epithelial dysplasia, suggesting that the carcinoma derived from a gastric duplication cyst that invaded the stomach. Duplication cysts should be included in the differential diagnosis of cystic masses of the gastrointestinal tract, and the possibility of malignancy within these cysts should be considered.

Adenocarcinoma↗
PubMed2004

Pathological change of articular cartilage in the mandibular head treated with immunosuppressant FK 506.

While several reports have documented immunosuppressant-induced osteoporosis, the exact mechanism of the pathological change of the joint remains to be clarified. In the present study, we have demonstrated the pathological change of the articular cartilage in the mandibular head of five Sprague-Dawley rats administered with the immunosuppressant FK 506 for 28 days. Three-dimensional micro-computed tomography of the mandibular heads in treated rats showed a significant decrease in trabecular bone volume compared to control rats. Histological observation revealed atrophic change of the articular cartilage. Immunohistological observation using anti-proliferative cell nuclear antibody (PCNA), type I, II, and type X collagen antibodies showed significantly decreased proliferation and differentiation of chondrocytes in the articular cartilage compared with the control group (p<0.05). Tartrate-resistant acid phosphatase (TRAP) staining revealed no significant difference in the numbers of osteoclasts at the chondro-osseous junction. Thus, FK 506 administration inhibited chondrogenic cell proliferation and differentiation and might cause osteoporotic change of subcartilage trabecular bone that subsequently forms in the mandibular head.

Animals↗
PubMed2003

Successful laparoscopic Ladd's procedure and appendectomy for intestinal malrotation with appendicitis.

We successfully performed a laparoscopic Ladd's procedure and an appendectomy in a 15-year-old girl with intestinal malrotation and appendicitis. She had tenderness and rebound pain in the umbilicus and left lower abdominal quadrant. Blood analysis revealed a moderate inflammatory response. Enhanced computerized tomography (CT) scanning revealed a whirl-like pattern and a superior mesentric vein (SMV) rotation sign in the mesentry of the small intestine. A swollen appendix was seen just below the umbilicus. An upper gastrointestinal (GI) radiological series confirmed agenesis of Treitz's arch. The patient was diagnosed as having a nonrotation type of malformation accompanied by acute appendicitis. She underwent a laparoscopic Ladd's procedure, an appendectomy, peritoneal lavage, and drainage. The technique for this procedure and its effectiveness are briefly discussed.

Adolescent↗
PubMed2001

Phot1 and phot2 mediate blue light regulation of stomatal opening.

The stomatal pores of higher plants allow for gaseous exchange into and out of leaves. Situated in the epidermis, they are surrounded by a pair of guard cells which control their opening in response to many environmental stimuli, including blue light. Opening of the pores is mediated by K(+) accumulation in guard cells through a K(+) channel and driven by an inside-negative electrical potential. Blue light causes phosphorylation and activation of the plasma membrane H(+)-ATPase that creates this potential. Thus far, no blue light receptor mediating stomatal opening has been identified, although the carotenoid, zeaxanthin, has been proposed. Arabidopsis mutants deficient in specific blue-light-mediated responses have identified four blue light receptors, cryptochrome 1 (cry1), cryptochrome 2 (cry2), phot1 and phot2. Here we show that in a double mutant of phot1 and phot2 stomata do not respond to blue light although single mutants are phenotypically normal. These results demonstrate that phot1 and phot2 act redundantly as blue light receptors mediating stomatal opening.

Arabidopsis↗
PubMed2001

Cellular origin of endochondral ossification from grafted periosteum.

Grafted periosteum is known to have potential for heterotopic bone formation by endochondral ossification. Although osteochondrogenic cells have been thought to originate from the osteogenic layer in grafted periosteum, no histological report has yet demonstrated this. The present study was designed to elucidate the origin of chondrogenesis preceding bone formation in grafted periosteum. Periostea harvested from young Japanese white rabbits' tibiae were grafted into suprahyoid muscles and examined radiographically and histologically at postoperative days 1, 7, 9, 14, 21, and 35. Normal periostea and tibial graft site were also examined. Surgical harvesting of the periosteum split and damaged its osteogenic layer but retained the fibrous layer intact. Most of the osteoblasts remained on the tibial bone surface, and only few cells of the osteogenic layer were present in grafted tissue. By the seventh day after grafting, the fibrous layer had thickened. The fibroblastic cells in the fibrous layer had significantly increased in number (P < 0.01) and were positively stained for proliferating cell nuclear antigen. These cells exhibited alkaline phosphatase activity at day 9. The differentiated chondrocytes had formed cartilage at postoperative day 14. Cells in the osteogenic layer appeared necrotic and subsequently disappeared. Following postoperative day 21, cartilage was replaced by trabecular bone. Bone formation was completed by 35 days. An X-ray analysis at this time also revealed new bone formation. These findings indicate that grafted periosteum forms bone by endochondral ossification and that the cells of the fibrous layer play essential roles in chondrogenesis that precedes such bone formation.

Alkaline Phosphatase↗
PubMed2001

Arabidopsis nph1 and npl1: blue light receptors that mediate both phototropism and chloroplast relocation.

UV-A/blue light acts to regulate a number of physiological processes in higher plants. These include light-driven chloroplast movement and phototropism. The NPH1 gene of Arabidopsis encodes an autophosphorylating protein kinase that functions as a photoreceptor for phototropism in response to low-intensity blue light. However, nph1 mutants have been reported to exhibit normal phototropic curvature under high-intensity blue light, indicating the presence of an additional phototropic receptor. A likely candidate is the nph1 homologue, npl1, which has recently been shown to mediate the avoidance response of chloroplasts to high-intensity blue light in Arabidopsis. Here we demonstrate that npl1, like nph1, noncovalently binds the chromophore flavin mononucleotide (FMN) within two specialized PAS domains, termed LOV domains. Furthermore, when expressed in insect cells, npl1, like nph1, undergoes light-dependent autophosphorylation, indicating that npl1 also functions as a light receptor kinase. Consistent with this conclusion, we show that a nph1 npl1 double mutant exhibits an impaired phototropic response under both low- and high-intensity blue light. Hence, npl1 functions as a second phototropic receptor under high fluence rate conditions and is, in part, functionally redundant to nph1. We also demonstrate that both chloroplast accumulation in response to low-intensity light and chloroplast avoidance movement in response to high-intensity light are lacking in the nph1 npl1 double mutant. Our findings therefore indicate that nph1 and npl1 show partially overlapping functions in two different responses, phototropism and chloroplast relocation, in a fluence rate-dependent manner.

Arabidopsis↗
PubMed2001

Arabidopsis NPL1: a phototropin homolog controlling the chloroplast high-light avoidance response.

Chloroplasts relocate their positions in a cell in response to the intensity of incident light, moving to the side wall of the cell to avoid strong light, but gathering at the front face under weak light to maximize light interception. Here, Arabidopsis thaliana mutants defective in the avoidance response were isolated, and the mutated gene was identified as NPL1 (NPH-like 1), a homolog of NPH1 (nonphototropic hypocotyl 1), a blue light receptor used in phototropism. Hence, NPL1 is likely a blue light receptor regulating the avoidance response under strong light.

Alleles↗
PubMed2001

Regulation of oligodendrocyte development.

Oligodendrocytes are myelinating cells in the central nervous system. Recent studies demonstrated that oligodendrocyte progenitor cells are generated from a restricted region in the ventricular zone. In the rodent spinal cord, progenitor cells appear from narrow and bilateral longitudinal columns in the ventral ventricular zone, and then migrate dorsally. This ventral-specific appearance of oligodendrocyte progenitors may be controlled along the dorso-ventral axis in the spinal cord by extrinsic signals secreted from both the dorsal and ventral cords. The combined action of the Notch signaling pathway and a basic helix-loop-helix class of transcription factors may modulate this early specification of spinal oligodendrocytes and also be involved in multiple steps of oligodendrocyte differentiation.

Animals↗
PubMed2001

Evx1 is a postmitotic determinant of v0 interneuron identity in the spinal cord.

Interneurons in the ventral spinal cord are essential for coordinated locomotion in vertebrates. During embryogenesis, the V0 and V1 classes of ventral interneurons are defined by expression of the homeodomain transcription factors Evx1/2 and En1, respectively. In this study, we show that Evx1 V0 interneurons are locally projecting intersegmental commissural neurons. In Evx1 mutant embryos, the majority of V0 interneurons fail to extend commissural axons. Instead, they adopt an En1-like ipsilateral axonal projection and ectopically express En1, indicating that V0 interneurons are transfated to a V1 identity. Conversely, misexpression of Evx1 represses En1, suggesting that Evx1 may suppress the V1 interneuron differentiation program. Our findings demonstrate that Evx1 is a postmitotic determinant of V0 interneuron identity and reveal a critical postmitotic phase for neuronal determination in the developing spinal cord.

Alleles↗
PubMed2001

Prefabricated bone graft induced from grafted periosteum for the repair of jaw defects: an experimental study in rabbits.

PURPOSE: The purpose of the study was to determine whether a prefabricated graft of new bone induced from periosteum grafted into muscle was an effective material for the repair of jaw defects. MATERIAL AND METHODS: Artificial mandibular jaw defects in young Japanese rabbits were covered either with free grafted periosteum (n = 5) or a prefabricated graft of newly formed bone induced from periosteum, which was first grafted into the floor of the mouth, and placed as a revascularized muscle-pedicled bone flap (n = 5). Bone formation in jaw defects was examined radiographically and histologically 28 days after grafting into defects. RESULTS: Bone formation was confirmed radiographically and histologically in both groups. However, the free grafted periosteum formed thin bone and fibrous tissue existed between the new and the original bone. In contrast, more active bone formation was observed with the prefabricated graft. This grafted new bone developed further and fused to the mandible. Blood vessels surrounding the new bone were observed histologically. CONCLUSION: These experimental findings suggested that prefabricated bone grafts induced from periosteum grafts are potentially useful for correction of jaw defects.

Animals↗
PubMed2001

Morphological changes and cellular dynamics of oligodendrocyte lineage cells in the developing vertebrate central nervous system.

Oligodendrocyte precursor cells (OPCs) originate in multiple restricted regions of the developing central nervous system (CNS). Here, we focus on morphological changes of oligodendrocyte lineage cells and their cellular dynamics including cell motility and proliferation. Morphological studies with molecular markers for OPCs suggest distinct spatiotemporal patterns of OPC migration in vivo, which are directly demonstrated by application of exogenous fluorescent markers to OPCs. Extensive proliferation of OPCs in the CNS parenchyma is also demonstrated by pulse labeling of the cells with bromodeoxyuridine. The results strongly suggest that oligodendrocyte lineage cells are highly motile and actively proliferate with an elongated morphology. These data provide insights into the potential molecular mechanisms of OPC dispersal throughout the CNS.

Animals↗
PubMed2000

Dorsal spinal cord inhibits oligodendrocyte development.

Oligodendrocytes are the myelinating cells of the mammalian central nervous system. In the mouse spinal cord, oligodendrocytes are generated from strictly restricted regions of the ventral ventricular zone. To investigate how they originate from these specific regions, we used an explant culture system of the E12 mouse cervical spinal cord and hindbrain. In this culture system O4(+) cells were first detected along the ventral midline of the explant and were subsequently expanded to the dorsal region similar to in vivo. When we cultured the ventral and dorsal spinal cords separately, a robust increase in the number of O4(+) cells was observed in the ventral fragment. The number of both progenitor cells and mature cells also increased in the ventral fragment. This phenomenon suggests the presence of inhibitory factor for oligodendrocyte development from dorsal spinal cord. BMP4, a strong candidate for this factor that is secreted from the dorsal spinal cord, did not affect oligodendrocyte development. Previous studies demonstrated that signals from the notochord and ventral spinal cord, such as sonic hedgehog and neuregulin, promote the ventral region-specific development of oligodendrocytes. Our present study demonstrates that the dorsal spinal cord negatively regulates oligodendrocyte development.

Animals↗
PubMed2000

Blue light-induced chloroplast relocation in Arabidopsis thaliana as analyzed by microbeam irradiation.

Chloroplast relocation in mesophyll cells of Arabidopsis thaliana was observed microscopically and analyzed by microbeam irradiation. Chloroplasts located along the anticlinal walls in dark-adapted cells. When part of a cell was irradiated with a microbeam of high fluence rate blue light (B) simultaneously with background red light (R) on the whole cell, the chloroplasts moved towards the B-irradiated area, but did not enter the beam. The background R illumination activated cytoplasmic motility as well as chloroplast movement. Without R illumination, there was little chloroplast relocation. In light-adapted cells in which the chloroplasts were spread over the cell surface perpendicular to the incident light, R-illumination had the same effect. Under background R, the chloroplasts moved out of the area irradiated with a B microbeam of 8 or 30 W m(-2) (avoidance response), but chloroplasts outside the beam moved towards the area irradiated with the B microbeam (accumulation response). These results suggest that the signals for accumulation and avoidance responses were generated in a single cell by high fluence rate B. cry1cry2, npq1 and nph1 mutants showed B-induced chloroplast relocation. Both the accumulation and avoidance responses were observed in all the mutants, although in the nph1 mutant, the sensitivity of accumulation movement was slightly lower than that of the wild type. We discuss the possible photoreceptor for B-induced chloroplast relocation.

Adaptation, Physiological↗
PubMed2000

Work of breathing during spontaneous ventilation in anesthetized children: a comparative study among the face mask, laryngeal mask airway and endotracheal tube.

Work of breathing (WOB) increases during general anesthesia in adults, but such information has been limited in pediatric patients. We studied WOB in 24 healthy children (mean age 2+/-1.9 yrs), during elective urogenital surgery under 1 minimum alveolar anesthetic concentration halothane-nitrous oxide anesthesia with a caudal block while breathing spontaneously. WOB was measured with an esophageal balloon, miniature flowmeter, and a computerized (Bicore) system. In each patient, WOB was computed under four conditions: a mask without oral airway (-AW), a mask with oral airway (+AW), a laryngeal mask airway (LMA), and an endotracheal tube (ETT). With each apparatus WOB was studied both with continuous positive airway pressure (CPAP) (5-6 cm H(2)O) and without CPAP (or zero end-expiratory pressure [ZEEP]). Under ZEEP, WOB (g x cm/kg) among the four apparatus were (mean +/- SEM): mask (-AW) (64 +/-19.2) > mask (+AW) (44+/-17.2), LMA (42+/-15.6) > ETT (25.4+/- 12.4) (P<0.05). WOB with CPAP significantly (P<0.05) decreased from WOB with ZEEP in three groups (mask [-AW], mask [+AW], and LMA), but not in the ETT group. Tidal volume (both ZEEP and CPAP) and end-tidal PCO(2) (with CPAP only) were significantly (P<0.05) decreased only in the ETT group, whereas no significant difference was found in respiratory rate or minute volume among the four airway apparatus groups, either with or without CPAP. The reduction in WOB, when breathing through ETT was primarily attributable to decreases in tidal volume and volume work. The finding that WOB decreases with CPAP in all groups except for the ETT group suggests that the decrease is a result of improved patency of the upper airway rather than of increases in functional residual capacity and lung compliance.

Anesthesia, Inhalation↗
PubMed2000

Attenuation of hyperoxia-induced diaphragmatic dysfunction with lidocaine in hamsters.

OBJECTIVE: Toxic free radicals cause dysfunction of respiratory muscles, probably leading to respiratory distress. Exposure to high concentrations of oxygen generates plenty of free radicals. Lidocaine scavenges the reactive molecules. The purposes of the current study were first to examine whether hyperoxia impairs diaphragmatic function, and second, to assess the effects of lidocaine on hyperoxia-induced diaphragmatic dysfunction, if developed. DESIGN: Prospective, randomized animal study. SETTING: University research laboratory. SUBJECTS: Forty and 48 adult male Golden-Syrian hamsters (110-150 g) in parts I and II studies, respectively. INTERVENTION: In the part I study, hyperoxia for 5 and 6 days reduced diaphragmatic contractility and enhanced fatigue. In the part II study, hamsters were randomly allocated to one of six groups (n = 8 each): exposure to air for 6 days with saline (group A-S) or lidocaine infusion (group A-L), exposure to 100% oxygen for 5 days with saline (group 05-S) or lidocaine (group 05-L), and exposure to 100% oxygen for 6 days with saline (group 06-S) or lidocaine (group 06-L). Saline or lidocaine (2 mg/kg/hr) was subcutaneously given immediately before exposure to air or oxygen. Diaphragmatic contractility and fatigability were assessed in vitro using muscle strips excised from the costal diaphragms. Diaphragmatic levels of malondialdehyde (MDA), an index of free radical-mediated lipid peroxidation, were measured. These variables were compared between groups. MEASUREMENTS AND MAIN RESULTS: Twitch and tetanic tensions in groups 05-S and 06-S were reduced compared with group A-S. Tensions generated during fatigue trials were also decreased in groups 05-S and 06-S. MDA levels were elevated in diaphragms from these groups. In groups 05-L and 06-L, contractile dysfunction, deterioration of fatigability, and MDA formation in the diaphragm were attenuated. CONCLUSIONS: Lidocaine attenuated hyperoxia-induced diaphragmatic dysfunction assessed by contractile profiles and fatigability in hamsters. This beneficial effect may be attributable, in part, to inhibition of lipid peroxidation.

Animals↗
PubMed2000

Lidocaine attenuates sepsis-induced diaphragmatic dysfunction in hamsters.

OBJECTIVES: Sepsis or endotoxemia causes diaphragmatic dysfunction, which may contribute to respiratory distress. Toxic free radicals are partly responsible for the pathogenesis. Lidocaine scavenges the reactive molecules. The purpose of the current study was to examine whether lidocaine prevents the diaphragmatic dysfunction of sepsis. DESIGN: Prospective, randomized animal study. SETTING: University research laboratory. SUBJECTS: A total of 40 male Golden-Syrian hamsters. INTERVENTIONS: The animals were randomly allocated to one of five groups (n = 8 each): hamsters undergoing sham laparotomy alone and receiving saline infusion (Sham group), those undergoing cecal ligation with puncture (CLP) and receiving an infusion of saline (Sepsis group), those undergoing sham laparotomy and receiving infusion of lidocaine, 2 mg/kg/hr (Sham-LID group), those undergoing CLP and receiving infusion of lidocaine, 1 mg/kg/hr (Sepsis-LID 1 group), and those undergoing CLP and receiving infusion of lidocaine, 2 mg/kg/hr (Sepsis-LID 2 group). Subcutaneous infusion of saline or lidocaine was started 6 hrs before surgery and continued until 24 hrs after the operation when all hamsters were killed. MEASUREMENTS AND MAIN RESULTS: Diaphragmatic contractility and fatigability were assessed in vitro by using muscle strips excised from the costal diaphragms. Diaphragmatic levels of malondialdehyde (MDA), an index of free radicals-mediated lipid peroxidation, were also measured. Twitch and tetanic tensions in the Sepsis group were reduced compared with the Sham group. Tensions generated during fatigue trials were decreased, and MDA levels were elevated in diaphragms from the Sepsis group. An infusion of 2 mg/kg/hr lidocaine attenuated contractile dysfunction, aggravation of fatigability, and the increase in MDA formation. In contrast, 1 mg/kg/hr lidocaine failed to do so. Electrophysiologic diaphragmatic characteristics in the Sham-LID group were similar to those in the Sham group. CONCLUSIONS: Pretreatment with 2 mg/kg/hr but not 1 mg/kg/hr lidocaine attenuated sepsis-induced diaphragmatic dysfunction in hamsters assessed by contractile profiles and endurance capacity. This beneficial effect of lidocaine may be attributable, in part, to inhibition of lipid peroxidation in the diaphragm.

Anesthetics, Local↗