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Biomedical subjects

K Yamada

Publications and source records attributed to K Yamada.

At least 271 records · Page 15Linked to original sources
PubMed2001

Condylar bony change and self-reported parafunctional habits in prospective orthognathic surgery patients with temporomandibular disorders.

OBJECTIVE: The purpose of this study was to investigate the relationship between self-reported parafunctional habits and condylar bony change and disk displacement in orthognathic surgery patients with signs and symptoms of temporomandibular joint disorders. STUDY DESIGN: This is a cross-sectional retrospective study of pretreatment helical computed tomography scans and questionnaires of 94 female orthognathic surgery patients. RESULTS: Condylar bony change, unilaterally or bilaterally, was found in 56.4% of the subjects, or 43.6% of the joints. Disk displacement, unilaterally or bilaterally, was seen in 59.6% of the subjects, or 45.7% of the joints. Bruxism and clenching was significantly associated with condylar bony change and disk displacement. Subjects with 3 or more parafunctional habits showed a significantly higher rate of bilateral condylar bony change. CONCLUSION: Our results suggest that bruxism and clenching might be related to deterioration of the temporomandibular joint and that the greater the number of parafunctional habits a subject has, the higher the risk of condylar bony change.

Bruxism↗
PubMed2001

Aerosolized surfactant therapy for endotoxin-induced experimental acute respiratory distress syndrome in rats.

We have compared the effects of inhalation of aerosolized surfactant on experimental acute respiratory distress syndrome. Escherichia coli endotoxin (55 (SD 20) mg kg(-1)) was injected into the tracheas of 36 adult rats anaesthetized and mechanically ventilated with pure oxygen. When the Pa(O(2)) decreased to 11.3 (3.3) kPa, the animals were randomly subjected to inhalation of aerosolized modified natural surfactant (MNS) for 0 min (control group), 30, 60, and 120 min. In the control group, Pa(O(2)) remained below 12 kPa for 180 min. In the groups receiving inhalation of surfactant for 30 and 60 min, Pa(O(2)) increased but decreased soon after termination of the inhalation. In contrast, Pa(O(2)) of the group receiving inhalation of surfactant for 120 min continued to increase, reaching 52.1 (12.5) kPa at 180 min (P<0.05 vs control). Thus, we conclude that improvement in gas exchange as a result of inhalation of MNS depends on the duration of inhalation.

Aerosols↗
PubMed2001

Hydrothorax: an unexpected complication after laparoscopic myomectomy.

We report a case of hydrothorax as a complication of laparoscopic myomectomy in an otherwise healthy woman. The most likely cause of the patient's hydrothorax was irrigation fluid moving from the peritoneal cavity into the pleural space via defects in the diaphragm. Anaesthesists and surgeons should consider hydrothorax as a potential complication in any patient undergoing laparoscopy.

Adult↗
PubMed2001

Pilot study of local radiotherapy for portal vein tumor thrombus in patients with unresectable hepatocellular carcinoma.

BACKGROUND: Patients suffering from hepatocellular carcinoma (HCC) with portal vein tumor thrombus (PVTT) generally have a poor prognosis. We therefore conducted a prospective pilot trial of combined transcatheter arterial chemoembolization (TACE) and local radiotherapy (RT) for PVTT in unresectable HCC. The aim of the study was to investigate the efficacy and toxicity of this preliminary trial regime and to explore RT guidelines for cirrhosis. METHODS: Eight patients with unresectable HCC accompanied by first branch PVTT were entered into the study from February 1998 to December 1999. TACE was performed using Lipiodol, epirubicin hydrochloride and mytomycin followed by gelatin sponge cubes. RT was started 10-14 days following TACE. A total delivered dose of 60 Gy was given as daily 2 Gy fractions, with the clinical target volume defined as PVTT only. We observed a relationship between deterioration of liver function and the percent volume of the total liver receiving a dose exceeding 30 Gy (V30). RESULTS: An objective response was observed in three of the eight patients. However, on follow-up angiograms the protrusion of PVTT into the main portal trunk was decreased in all cases. Deterioration of liver function was observed in all patients with V30 >40%. CONCLUSION: It is possible that this combined therapy prevents PVTT from spreading to the main trunk and that indicates a further benefit of TACE. Our results indicate that V30 constitutes a predictive test for the development of liver failure. More detailed evaluations of liver function and determination of the safe irradiation volume are necessary.

Aged↗
PubMed2001

Synthesis and antiviral evaluation of alpha-D-2',3'-didehydro-2',3'-dideoxy-3'-C-hydroxymethyl nucleosides.

A series of hydroxymethyl branched analogues of antiviral apio d4Ns was synthesized from D-arabinose. The SN2' ring opening reaction of 2,2'-anhydro-alpha-D-pyrimidinenucleoside (10) was mainly investigated. The reaction selectively gave SN2' adducts, which were deprotected to furnish the desired alpha-D-2',3'-didehydro-2',3'-dideoxy-3'-C-hydroxymethyl nucleosides (2).

Antiviral Agents↗
PubMed2001

A case of anterior open bite developing during adolescence.

Imaging studies have reported on the relationship between temporomandibular joint (TMJ) degeneration and facial deformity. These studies have suggested that mandibular growth is affected by TMJ degeneration, resulting in altered skeletal structure as mandibular retrusion. However, there are very few longitudinal case reports on TMJ osteoarthrosis (OA). Progressive open bite occurred in an adolescent patient with TMJ OA. Cephalometric analysis showed a downward and backward rotated mandible, and a labial inclination of the upper incisor. Magnetic resonance imaging showed internal derangement without reduction and erosion in the right and the left condyles. Although the cause of open bite is unclear in this case, tongue thrusting, and internal derangements in the temporomandibular joint were suspected as causes of the open bite.

Bone Resorption↗
PubMed2001

The human homologue of fission Yeast cdc27, p66, is a component of active human DNA polymerase delta.

An essential eukaryotic DNA polymerase, DNA polymerase delta (pol delta), synthesizes DNA processively in the presence of proliferating cell nuclear antigen (PCNA). Recently, a 66 kDa polypeptide (p66) that displays significant homology within its PCNA binding domain to that of fission yeast cdc27 was identified as a component of mouse and calf thymus pol delta. Our studies show that p66 interacts tightly with other subunits of pol delta during size fractionation of human cell extracts, and co-immunoprecipitates with these subunits along with PCNA-dependent polymerase activity. Active human pol delta could be reconstituted by co-expressing p125, p50, and p66 recombinant baculoviruses, but not by co-expressing p125 and p50 alone. Interaction studies demonstrated that p66 stabilizes the association between p125 and p50. Pull-down assays with PCNA-linked beads demonstrated that p66 increases the overall affinity of pol delta for PCNA. These results indicate that p66 is a functionally important subunit of human pol delta that stabilizes the pol delta complex and increases the affinity of pol delta for PCNA.

Animals↗
PubMed2001

Arginine-specific ADP-ribosyltransferase on the surface of gizzard smooth muscle cells and the involvement of phosphatidylinositol 3-kinase in maintaining the activity of this transferase.

An arginine-specific ADP-ribosyltransferase activity was detected in chicken gizzard smooth muscle, and the specific activity is highest in the membrane fraction. This transferase is released from the membrane fraction by phosphatidylinositol-specific phospholipase C (PI-PLC), suggesting that it is a glycosylphosphatidylinositol (GPI)-anchored protein. When primary cultured gizzard smooth muscle cells (SMCs) were incubated with [adenylate-(32)P]NAD, several proteins were labeled. The labeling was inhibited by preincubation of the cells with PI-PLC, or by the addition of L-arginine to the reaction, and was sensitive to hydroxylamine treatment. The activity of the transferase was maintained in differentiated SMCs cultured with insulin, but was dramatically decreased concomitantly with cell dedifferentiation induced by serum or a specific PI3-kinase inhibitor, LY294002. These results indicate that the GPI-anchored arginine-specific ADP-ribosyltransferase is expressed on the surface of differentiated SMCs and can modify several cell surface proteins. Our results also suggest that PI3-kinase is involved in the regulation of transferase activity during differentiation.

ADP Ribose Transferases↗
PubMed2001

Sp family members stimulate transcription of the hex gene via interactions with GC boxes.

The 5'-flanking region of the mouse Hex gene was examined in order to identify transcription factors regulating its expression in hepatocytes and haematopoietic cells. We have identified two further GC boxes (GC boxes 3 and 4 at nucleotide positions -149 to -140 and -79 to -70, respectively), i.e. in addition to the two previously determined ones (GC boxes 1 and 2 at nucleotide positions -197 to -188 and -176 to -167, respectively). Luciferase reporter assays revealed that all four GC boxes are transcriptionally active in both MH(1)C(1) rat hepatoma and K562 human chronic myelogenous leukemia cells. Electrophoretic mobility shift assays with specific competitors and antibodies showed that members of the Sp family, namely Sp1 and Sp3, bind to these GC boxes. Overexpression of Sp1 and Sp3 in Drosophila SL2 cells stimulated transcription of the Hex gene through interactions with GC boxes 1 to 4, Sp1 being a more potent activator than Sp3. Thus, we conclude that Sp1 and Sp3 stimulate transcription of the Hex gene in both MH(1)C(1) and K562 cells.

Animals↗
PubMed2001

A proteinase-storing body that prepares for cell death or stresses in the epidermal cells of Arabidopsis.

Plants degrade cellular materials during senescence and under various stresses. We report that the precursors of two stress-inducible cysteine proteinases, RD21 and a vacuolar processing enzyme (VPE), are specifically accumulated in approximately 0.5 microm diameter x approximately 5 microm long bodies in Arabidopsis thaliana. Such bodies have previously been observed in Arabidopsis but their function was not known. They are surrounded with ribosomes and thus are assumed to be directly derived from the endoplasmic reticulum (ER). Therefore, we propose to call them the ER bodies. The ER bodies are observed specifically in the epidermal cells of healthy seedlings. These cells are easily wounded and stressed by the external environment. When the seedlings are stressed with a concentrated salt solution, leading to death of the epidermal cells, the ER bodies start to fuse with each other and with the vacuoles, thereby mediating the delivery of the precursors directly to the vacuoles. This regulated, direct pathway differs from the usual case in which proteinases are transported constitutively from the ER to the Golgi complex and then to vacuoles, with intervention of vesicle-transport machinery, such as a vacuolar-sorting receptor or a syntaxin of the SNARE family. Thus, the ER bodies appear to be a novel proteinase-storing system that assists in cell death under stressed conditions.

Adaptation, Physiological↗
PubMed2001

Cloning and functional expression of an E box-binding protein from rat granulosa cells.

Ovarian granulosa cells undergo cell growth and cytodifferentiation during follicular maturation. In a number of tissues, the gene expression that is responsible for the cytodifferentiation is largely dependent on E box(es) located upstream of the responsible genes. In this study, we report on the cloning of cDNA(s) encoding E box (5'-CACGTG-3')-binding protein from a rat granulosa cell cDNA library using a yeast one-hybrid system. When multiple E box sequences were used as target, we obtained a positive clone that encodes the rat homologue of upstream stimulatory factor 2 (USF2). An analysis of the nucleotide sequence and its deduced amino acid sequence reveals that rat USF2 protein consists of 346 amino acid residues and belongs to the basic helix-loop-helix/leucine zipper protein family. Northern blot analysis shows that rat USF2 mRNA exists as multiple forms between 1.6 and 2.2 kilobases. The size of the cloned insert was identical to that of the transcript of maximal length. Electrophoretic mobility shift assays showed that in vitro-translated rat USF2 specifically binds to the E box. In addition, cotransfection experiments with luciferase-reporter constructs in HepG2 cells reveal that the overexpression of rat USF2 leads to an increase of luciferase activity in the E box sequence-dependent manner. Thus, we report molecular cloning, expression, and functional characterization of full-length rat USF2 cDNA.

Amino Acid Sequence↗
PubMed2001

Inhibitory action of leptin on early follicular growth differs in immature and adult female mice.

In order to investigate the action of leptin on early follicular growth, preantral follicles, 95-115 microm in diameter were mechanically isolated from the ovaries of BDF1 hybrid immature (11-day-old) and adult (8-wk-old) mice, and cultured for 4 days in vitro. Follicular growth was assessed by daily changes in follicular diameter and by the amount of estradiol and immunoreactive (IR)-inhibin released into the culture medium at Day 4. Preantral follicles from immature mice showed a significant development in follicular growth as a result of stimulation by GH (1 mIU/ml), insulin-like growth factor (IGF)-I (100 ng/ml) + FSH (100 mIU/ml), and GH (1 mIU/ml) + FSH (100 mIU/ml). Although leptin at concentrations of 1-1000 ng/ml did not have any significant effect on follicular growth stimulated by IGF-I or GH, it significantly inhibited follicular growth in a dose-related manner when follicles were stimulated by IGF-I + FSH and GH + FSH, respectively, suggesting that leptin attenuated the additive effect of FSH. On the other hand, preantral follicles from adult mice were cultured in the presence of FSH, and FSH-dependent follicular growth was inhibited by leptin in a dose-related manner. Because FSH stimulates cAMP production, we investigated the involvement of cAMP in the inhibitory mechanisms of leptin. Preantral follicles from immature and adult mice were cultured in the presence of either 8-Br-cAMP or forskolin. Both 8-Br-cAMP and forskolin significantly increased follicular diameter and hormone secretion in both immature and adult mice. However, 8-Br-cAMP and forskolin-stimulated follicle growth and hormone secretion were significantly inhibited in immature mice by coadministration of leptin, whereas growth of preantral follicles from adult mice was not inhibited by addition of leptin to cultures. These results indicate that leptin causes an inhibitory effect on the early follicular development of both immature and adult mice, but the inhibitory mechanisms of leptin are different.

Aging↗
PubMed2001

Effects of sarpogrelate hydrochloride on adenosine diphosphate- or collagen-induced platelet responses in arteriosclerosis obliterans.

To evaluate the effects of the 5-HT2 receptor antagonist sarpogrelate hydrochloride (sarpogrelate) on platelet responses in arteriosclerosis obliterans (ASO), we examined platelet aggregation and its relationships to platelet-derived growth factor (PDGF), soluble P-selectin (sP-selectin), and transforming growth factor-beta 1 (TGF-beta1). Circulating plasma levels of PDGF and sP-selectin in 13 patients with ASO after 1 week of medication with sarpogrelate were significantly lower than those before medication. In contrast, circulating plasma levels of TGF-beta1 after medication were significantly higher than those before medication. When platelet-rich plasma obtained from ASO patients after medication was stimulated with adenosine diphosphate (ADP) or collagen, platelet aggregation was suppressed compared with rates before medication. Significant decreases in levels of PDGF, sP-selectin and TGF-beta1 released from platelets in response to 5 micromol/l ADP and 1 microg/ml collagen after taking of sarpogrelate were found. There were close correlations between platelet aggregation and respective molecules released from platelets. In conclusion, since platelet activation is involved in pathogenesis of thrombotic disease, sarpogrelate may suppress the development of obstructive arteriosclerosis. PDGF and TGF-beta1, as well as sP-selectin, appear to be useful markers for clinical evaluation of anti-platelet drugs.

Adenosine Diphosphate↗
PubMed2001

Follow-up study of conservative treatment for atlantoaxial rotatory displacement.

Rotatory displacement of the atlantoaxial joint is one of the causes of torticollis in children. Some of these cases show persistent symptoms and may lead to rotatory fixation; however, only a few studies have been directed to the prognosis of atlantoaxial rotatory displacement after conservative treatment. Clinical and radiographic reviews were performed in 35 patients (16 male and 19 female) with rotatory displacement of the atlantoaxial joint. The mean age at admission was 6.5 (range: 2-12) years old, and the mean follow-up period was 3.4 (1.4-5.8) years. All patients successfully achieved reduction after 2 to 3 weeks of continuous halter traction; however, 9 patients (25.7%) experienced recurrence, and 7 patients (20.0%) had a slight torticollis at follow-up. The duration of symptoms before treatment affected the recurrence rate, and the torticollis was apt to remain in cases with severe displacement at admission.

Atlanto-Axial Joint↗
PubMed2001

Enhanced formation of fibrosis in a rabbit aneurysm by gelatin hydrogel incorporating basic fibroblast growth factor.

OBJECTIVE: This study was undertaken to analyze whether the controlled release of basic fibroblast growth factor (bFGF) can promote intrasaccular thrombosis in an experimental aneurysmal model. METHODS: Carotid aneurysms were constructed in 80 rabbits with venous pouches and treated by placing gelatin hydrogels into each aneurysm incorporating 0, 25, 50, or 100 microg of bFGF or incorporating 100 microg of bFGF with different water contents. In the controls, the venous pouches either were not treated or were treated with gauze alone. Gelatin hydrogel was used for the controlled release of bFGF into the aneurysms. The formation of fibrosis in the aneurysms was histologically viewed to assess the area occupied by the fibrous tissues at 3 and 6 weeks after the hydrogel application. The effect of the bFGF dose and water content on obliterating the aneurysm by the hydrogels incorporating bFGF was also investigated. RESULTS: Six weeks after the application of gelatin hydrogels with a water content of 95 wt% incorporating 100 microg of bFGF, the lateral pouch orifice was completely closed, obliterating the aneurysm at the level of tissue appearance, in contrast to hydrogels incorporating lower doses of bFGF and other control agents. The venous pouch aneurysm was histologically occupied with the newly formed fibrous tissue, and the fibrous tissue area and percentage of the aneurysmal lumen occupied by the fibrosis-gauze complex were significantly larger than those of other hydrogel applications (P < 0.05). The neointima tissue was homogeneously covered with a monolayer of Factor VIII-positive cells. The fact that there was no difference in the water content in the fibrosis formation induced by the bFGF-incorporated gelatin hydrogels indicated that the hydrogel biodegradability did not affect the obliteration of the aneurysm. CONCLUSION: Local controlled release of bFGF stimulated the formation of in vivo fibrosis, resulting in obliteration of the aneurysm. The long-term results of the fibrous organization remain speculative.

Animals↗
PubMed2001

Equivalent network representation for thickness vibration modes in piezoelectric plates with a linearly graded parameter.

Equivalent network representation is derived for thickness vibration modes in piezoelectric plates with a linearly graded parameter. The network is composed of a transmission line of a finite length, which is linked to the electric excitation port via ideal transformers connected serially at both ends. The ratios of the two transformers are different from each other and frequency dependent. Two frequency-dependent capacitors of the same value but opposite sign appear at the electric port. The frequency characteristic of the input electric admittance of the resonator, which shows the unique feature of the graded piezoelectric plate, is demonstrated by the equivalent network analysis.

Letter↗
PubMed2001

T-cell differentiation of human and non-human primate CD34+ hematopoietic progenitor cells using porcine thymic stroma.

Transplantation of swine thymic tissue has been proposed as an approach to reconstitute the immune system of HIV-infected individuals. This is an attractive strategy because miniature swine are readily available as donors and porcine tissue is resistant to infection with HIV-1. Demonstration that porcine thymus tissue supports primate T-cell differentiation is critical to the ultimate utility of this approach. Using a thymic stroma culture system we have previously described [Rosenzweig M, Marks DF, Zhu H et al. In vitro T lymphopoiesis of human and rhesus CD34+ progenitor cells. Blood 1996; 87: 4040], we demonstrate that porcine thymus tissue is able to promote the in vitro T-lymphocyte differentiation of both human and non-human primate hematopoietic progenitor cells. CD34+ hematopoietic progenitors differentiated into both double positive (CD4+CD8+) and single positive thymocytes expressing CD4 or CD8 alone. A polyclonal T-cell repertoire was evident. In addition, the T cells responded appropriately to mitogen and were permissive to infection with simian immunodeficiency virus (SIV). These data demonstrate the ability of porcine thymus to support T-cell differentiation of both human and non-human hematopoietic progenitor cells and support in vivo studies of transplantation of swine thymic tissue as a strategy for immune reconstitution in AIDS.

Animals↗