Biomedical subjects

H Kawamura

Publications and source records attributed to H Kawamura.

At least 55 records · Page 3Linked to original sources

PubMed2001

Factors affecting range of flexion after total knee arthroplasty.

Many factors affect postoperative range of flexion after total knee arthroplasty (TKA). The purpose of this study was to identify the most important factors that affect range of knee flexion after TKA. Sixty-five patients (73 knees) were treated with Genesis II knee replacements. Minimum follow-up was 2 years. Patient demographics (sex, age, body mass index, previous surgery, component type, patella resurfacing, preoperative Knee Society score preoperative range of motion) and radiographic measurements (preoperative tibiofemoral varus/valgus angle, height of the joint line, length of the patellar tendon, shift and tilt angle of the patella) were analyzed statistically. Among these factors, preoperative range of flexion, positively, and preoperative varus/valgus tibiofemoral angle, negatively, affected postoperative range of flexion. The tilt angle of the patella and the tilt angle of the patellar button approached statistical significance in revealing a negative relation with postoperative range of flexion. TKAs in which the patella was not resurfaced tended to lose range of flexion, whereas TKAs in which the patella was resurfaced tended to have no loss of flexion, although the number of TKAs in which the patella was not resurfaced was small. In conclusion, preoperative range of flexion and preoperative varus/valgus tibiofemoral angle affected postoperative range of flexion. The tilt angle of the patella and tilt angle of the patellar button may be factors that affect postoperative range of flexion.

Aged↗

PubMed2001

Ultrastructural, morphometric, and hormonal analysis of the effects of testosterone treatment on Leydig cells and other interstitial cells in young adult rats.

Early effects of testosterone (T) treatment on the ultrastructure of testicular interstitium were analyzed by morphometry. In T-treated young adult rats the T-LH feed-back loop functioned as expected and the marked increase in peripheral T caused almost complete depletion of peripheral LH. Even though the peripheral LH concentration was almost undetectably low, the Leydig cells maintained regulatory interactions with macrophages, peritubular myoid cells and with the seminiferous epithelium lining the tubular lumina as indicated by the high correlations of morphometric parameters between the Leydig and other cell types. The morphometric alterations in the ultrastructure of Leydig cells suggest that the seminiferous tubules may signal by releasing inhibitory paracrine factors affecting the morphology and function of Leydig cells in T-treated young adult rats. The morphometry of Leydig cells in T-treated young adult rats showed a significant quantifiable reduction in nuclei and organelles involved in steroid synthesis and this analysis also offers a good basis for elucidation of the early effects of testosterone in terms of its contraceptive function as well as of different toxic compounds on reproductive functions.

Animals↗

PubMed2001

Intensive generation of NK1.1- extrathymic T cells in the liver by injection of bone marrow cells isolated from mice with a mutation of polymorphic major histocompatibility complex antigens.

Whether intermediate TCR (TCRint) cells and natural killer T (NKT or NK1.1+TCRint) cells are extrathymically generated remains controversial. This arises from the fact that there are few of these T cells in athymic nude mice and neonatally thymectomized mice. However, when athymic mice were provided with appropriate microenvironments or stimulation, many TCRint cells (mainly NK1.1-) were found to arise in the liver. NKT cells are known to be positively selected by monomorphic major histocompatibility complex (MHC) -like antigens (e.g. CD1d). This is true even if they are CD4+. In other words, a MHC class I-like antigen is restricted to CD4 antigen. This rule is somewhat different from that seen in conventional T cells (i.e. the restriction of class II with CD4 and that of class I and CD8). In the case of NK1.1-TCRint cells, they were selected by polymorphic MHC antigens, but their MHC restriction to CD4 or CD8 antigen was incomplete. This was revealed by experiments of bone marrow transfer with class I (bm 1) or II (bm 12) disparity. Depending on the disparity, a unique cytokine profile in sera was detected. These results suggest that the development of T lineage lymphocytes and MHC restriction to CD4 and CD8 might have occurred in parallell as a phylogenic event, and that NK1.1- extrathymic T cells (i.e. NK1.1-TCRint) are at an intermediate position between NKT cells and conventional T cells in phylogeny.

Aging↗

PubMed2001

Polyethylene wear of the porous-coated anatomic total hip arthroplasty with an average 11-year follow-up.

The purpose of this study was to identify the factors that affect polyethylene wear of 55 porous-coated anatomic total hip arthroplasties after 9 to 14 years selected from a study population of 311 implants. The average three-dimensional linear, two-dimensional linear, and volumetric wear rates were 0.096 mm/y, 0.052 mm/y, and 34 mm3/y. Negative wear was noted in 7 patients using two-dimensional techniques. Significantly higher volumetric wear rate was observed for men (48 mm3/y) compared with women (24 mm3/y; P<.01), for patients <60 years old (45 mm3/y) compared with patients >60 years old (25 mm3/y; P<.01), and for 32-mm femoral heads (54 mm3/y) compared with 26-mm femoral heads (29 mm3/y; P<.01). Volumetric wear rate for patients having small (39 mm3/y) and large (65 mm3/y) areas of osteolysis were 2 and 3 times greater than for patients having no osteolysis (21 mm3/y) (P<.01).

Analysis of Variance↗

PubMed2001

Effect of pumping with injection of sodium hyaluronate and the other factors related to outcome in patients with non-reducing disk displacement of the temporomandibular joint.

We retrospectively examined the effect of pumping with injection of sodium hyaluronate into the temporomandibular joint (TMJ) and the other factors influencing outcome in patients with non-reducing disk displacement of the TMJ. Fifty-nine patients underwent pumping with injection of sodium hyaluronate into the TMJ. As control, 62 patients were observed without any treatment. Both groups were observed for 12 months. The relation between outcome and the following clinical characteristics was also studied: sex, age, range of motion for maximal mouth opening, TMJ pain, TMJ noise, tenderness of masticatory muscles, locking duration, intercuspal occlusions, angle of posterior slope of articular eminence and degenerative bony changes of the condyle. Logistic regression analysis revealed that pumping with injection of sodium hyaluronate was related to a good outcome. Clinical characteristics of presentation significantly related to a good outcome were a large maximal mouth opening, a short locking duration, and a steep posterior slope of articular eminence. We conclude that pumping with injection of sodium hyaluronate into the TMJ is an effective treatment method for non-reducing disk displacement of the TMJ and that some clinical characteristics also influence outcome.

Adjuvants, Immunologic↗

PubMed2001

Pumping injection of sodium hyaluronate for patients with non-reducing disc displacement of the temporomandibular joint: two year follow-up.

Objectives: The purpose of the present study was to examine the long-term effect of pumping injection of sodium hyaluronate into the TMJ in patients with non-reducing disc displacement. Patients: Sixty patients with non-reducing disc displacement underwent pumping injection of sodium hyaluronate (pumping group). Seventy-six patients with non-reducing disc displacements were observed without any active treatment (observation group). Study design: In both patient groups clinical signs and symptoms were observed periodically for 2 years. Variables such as age, range of maximum mouth opening, angle of posterior slope of the articular eminence and degenerative bony changes of the condyle at the initial visit were also examined. Cox hazards analysis was applied to examine the clinical outcome for such variables in addition to the results of pumping injection of sodium hyaluronate. Results: Pumping injection of sodium hyaluronate seemed to have a favourable effect when compared with the control group (untreated) (p=0.0002). However, the four background variables mentioned could not be explained as predictors of outcome. Conclusion: Pumping injection of sodium hyaluronate seems to be effective for non-reducing disc displacement of the temporomandibular joint. Copyright 2001 European Association for Cranio-Maxillofacial Surgery.

Journal Article↗

PubMed2001

Prognostic significance of lymph node involvement in middle and distal bile duct cancer.

BACKGROUND: Although lymph node involvement is considered an important prognostic factor, a detailed analysis has not been conducted in middle (Bm) and distal (Bi) bile duct cancer. METHODS: The histopathology of resections taken from 59 patients with Bm and Bi disease (Bm, 33 patients; Bi, 26 patients) was examined. The prevalence of lymph node involvement and its relationship to recurrence and prognosis were investigated. Survival rates were investigated according to the number of metastatic lymph nodes found, the TNM nodal stages, and the nodal stage classifications of The General Rules of the Japanese Society of Biliary Surgery. RESULTS: The frequency of nodal involvement in Bm and Bi was 45.5% and 30.8%, respectively. A significant correlation existed between a patient's prognosis and his TNM nodal stage, Japanese Society of Biliary Surgery nodal stage, and the number of metastatic lymph nodes found (P <.0001, respectively). Among 8 sites of postoperative recurrence, metastasis occurred most frequently in the liver (16/23). Patients with nodal involvement had a significantly higher rate of liver metastasis (10/23) than those without it (6/36) (P =.024). CONCLUSIONS: The number of metastatic lymph nodes found in patients with Bm or Bi cancer, and the nodal stage of their nodes, are significant prognostic indicators. Patients with nodal involvement are at high risk for liver metastasis in Bm and Bi disease.

Adult↗

PubMed2001

Platelet-derived growth factor-BB: a survival factor for the retinal microvasculature during periods of metabolic compromise.

PURPOSE: The aim of this study was to test the hypothesis that platelet-derived growth factor (PDGF) reduces ischemia-induced damage to cells in the retinal microvasculature. METHODS: As a model of ischemia, pericyte-containing microvessels freshly isolated from the adult rat retina were exposed to the inhibitors of ATP synthesis, iodoacetate and antimycin A. Cell viability was assayed by trypan blue exclusion. RESULTS: PDGF-BB significantly reduced cell death induced by chemical ischemia. The half-maximally effective concentration was approximately 15 pM. In contrast to PDGF-BB, which is the specific ligand for PDGF-beta receptors, ischemic death was not reduced by PDGF-AA, which does not activate the beta-receptors. The protective effect of PDGF-BB was blocked by tolbutamide, which is an inhibitor of ATP-sensitive potassium (K(ATP)) channels and mimicked by the K(ATP) channel opener, pinacidil. Nifedipine, which blocks voltage-gated calcium channels (VGCC's), also mimicked the protective effect of PDGF-BB. Consistent with PDGF-BB and nifedipine preventing cell death via a common mechanism, i.e., reducing VGCC activity, the maximal effects of this growth factor and the calcium channel blocker were not additive. CONCLUSIONS: Our results indicate that PDGF-BB significantly reduces the vulnerability of retinal microvessels to damage caused by profound ischemia. During episodes of metabolic compromise, it appears likely that the opening of K(ATP) channels via activation of PDGF-beta receptors initiates an adaptive mechanism to enhance the survival of the retinal microvasculature.

Adenosine Triphosphate↗

PubMed2001

The mechanism to suppress photosynthesis through end-product inhibition in single-rooted soybean leaves during acclimation to CO(2) enrichment.

Single-rooted soybean leaves were used to investigate the suppression of photosynthesis through end-product inhibition during acclimation to CO(2 )enrichment. The photosynthetic activity was greater in leaves cultured at a CO(2) partial pressure of 70 Pa (high-CO(2)) than that in the leaves cultured at 35 Pa CO(2) (control) during the initial exposure to CO(2) enrichment but then decreased rapidly with a large accumulation of starch, to well below the level of the control leaves. The response curve of photosynthesis (A) to the intercellular CO(2) concentration (Ci) in the high-CO(2) leaves cultured long-term exhibited a significantly low initial gradient. However, on exposure to darkness for 48 h, the initial gradient of the A to Ci curve and rate of photosynthesis were completely restored, and almost all of the accumulated starch was expended. The ribulose bisphosphate carboxylase (RuBPcase) content and activation ratio in the high-CO(2) leaves remained high and roughly constant during the experiment, and were unchanged by the exposure, while this enzyme was slightly inactivated or inhibited after long-term exposure to CO(2) enrichment. The lower rate of photosynthesis in the high-CO(2) leaves could be linearly increased to a rate approaching the control level by increasing the external atmospheric [CO(2)], which thereby compensated for a reduced CO(2) transfer diffusion from the intercellular space to the stroma in chloroplasts. It is consequently concluded that, during the acclimation to CO(2 )enrichment, the suppression of photosynthesis through end-product inhibition was mainly caused by a lowering of the carboxylation efficiency of RuBPcase due to hindrance of CO(2) diffusion from the intercellular space to the stroma in chloroplasts brought about by the large accumulation of starch.

Adaptation, Physiological↗

PubMed2001

Large-scale cDNA analysis of the maternal genetic information in the egg of Halocynthia roretzi for a gene expression catalog of ascidian development.

The ascidian egg is a well-known mosaic egg. In order to investigate the molecular nature of the maternal genetic information stored in the egg, we have prepared cDNAs from the mRNAs in the fertilized eggs of the ascidian, Halocynthia roretzi. The cDNAs of the ascidian embryo were sequenced, and the localization of individual mRNA was examined in staged embryos by whole-mount in situ hybridization. The data obtained were stored in the database MAGEST (http://www.genome.ad.jp/magest) and further analyzed. A total of 4240 cDNA clones were found to represent 2221 gene transcripts, including at least 934 different protein-coding sequences. The mRNA population of the egg consisted of a low prevalence, high complexity sequence set. The majority of the clones were of the rare sequence class, and of these, 42% of the clones showed significant matches with known peptides, mainly consisting of proteins with housekeeping functions such as metabolism and cell division. In addition, we found cDNAs encoding components involved in different signal transduction pathways and cDNAs encoding nucleotide-binding proteins. Large-scale analyses of the distribution of the RNA corresponding to each cDNA in the eight-cell, 110-cell and early tailbud embryos were simultaneously carried out. These analyses revealed that a small fraction of the maternal RNAs were localized in the eight-cell embryo, and that 7.9% of the clones were exclusively maternal, while 40.6% of the maternal clones showed expression in the later stages. This study provides global insights about the genes expressed during early development.

Animals↗

PubMed2001

[The approaches to factors which cause medication error--from the analyses of many near-miss cases related to intravenous medication which nurses experienced].

Given the complexity of the intravenous medication process, systematic thinking is essential to reduce medication errors. Two thousand eight hundred cases of 'Hiyari-Hatto' were analyzed. Eight important factors which cause intravenous medication error were clarified as a result. In the following I summarize the systematic approach for each factor. 1. Failed communication of information: illegible handwritten orders, and inaccurate verbal orders and copying cause medication error. Rules must be established to prevent miscommunication. 2. Error-prone design of the hardware: Look-alike packaging and labeling of drugs and the poor design of infusion pumps cause errors. The human-hardware interface should be improved by error-resistant design by manufacturers. 3. Patient names similar to simultaneously operating surgical procedures and interventions: This factor causes patient misidentification. Automated identification devices should be introduced into health care settings. 4. Interruption in the middle of tasks: The efficient assignment of medical work and business work should be made. 5. Inaccurate mixing procedure and insufficient mixing space: Mixing procedures must be standardized and the layout of the working space must be examined. 6. Time pressure: Mismatch between workload and manpower should be improved by reconsidering the work to be done. 7. Lack of information about high alert medications: The pharmacist should play a greater role in the medication process overall. 8. Poor knowledge and skill of recent graduates: Training methods and tools to prevent medication errors must be developed.

Communication↗

PubMed2001

The porous coated anatomic total hip replacement. A ten to fourteen-year follow-up study of a cementless total hip arthroplasty.

BACKGROUND: We previously reported our two and five-year results of arthroplasty with the Porous Coated Anatomic total hip prosthesis. We now report on the performance of this prosthesis at ten to fourteen years. METHODS: The results of 311 total hip replacements in which a Porous Coated Anatomic prosthesis was inserted without cement in 279 patients were analyzed prospectively. The average age of the patients at the time of the replacement was sixty--one years (range, twenty to eighty-one years). Sixty-four patients (seventy-six hips) died postoperatively. Forty-five patients (forty-seven hips) were lost to follow-up, and four were excluded because of their medical condition. One hundred and sixty-eight patients (187 hips) were followed for ten to fourteen years (average, twelve years). Seventeen of those patients (seventeen hips) had a revision. RESULTS: The overall survival rate (with any revision as the end point) was 90.0% +/- 5.4% at fourteen years, with an average Harris hip score of 85 +/- 14 points. The prevalence of thigh pain was 36% (fifty-six of 157) in the late period (more than ten years postoperatively). Radiographs showed stable fixation, with bone ingrowth, of 83% (130) of the 156 acetabular components and 88% (137) of the 156 femoral components at the latest follow-up evaluation. Men had a significantly higher rate of femoral osteolysis than did women (p < 0.001). The rates of acetabular and femoral osteolysis associated with 32-mm femoral heads (49% [twenty-three] of forty-seven and 70% [thirty-three] of forty-seven, respectively) were significantly higher (p < 0.01) than those associated with 26-mm heads (26% [twenty-eight] of 109 and 30% [thirty-three] of 109, respectively). Despite this, revision (removal or exchange of components) was not directly related to head size; instead, it was related to polyethylene thickness. CONCLUSIONS: There have been persistent problems with the Porous Coated Anatomic hip system, including thigh pain and an increasing prevalence of osteolysis with time. Revision because of aseptic loosening was related more to the thickness of the polyethylene liner than to the size of the femoral head. Femoral heads with a 32-mm diameter did not increase the risk for revision provided that an adequate thickness of polyethylene had been used.

Adult↗

PubMed2000

An ascidian glycine-rich RNA binding protein is not induced by temperature stress but is expressed under a genetic program during embryogenesis.

We have cloned a putative ascidian glycine-rich RNA binding protein gene, CiGRP1. Its maternal transcript and protein are stored in the unfertilized egg. They are gradually decreased during the first few rounds of cleavage. The CiGRP1 zygotic transcript and protein start to accumulate at the gastrula stage. The CiGRP1 transcript is expressed in the brain precursor and mesenchyme precursor cells of the gastrula and the neurula stage, and the brain and mesenchyme cells of the tailbud stage embryo. The CiGRP1 protein is found in all nuclei and in the cytoplasm of brain and mesenchyme cells. Although many glycine-rich RNA binding protein homologs of plants and vertebrates are cold-inducible, CiGRP1 cannot be induced by cold shock or heat shock at the transcriptional and translational levels during embryogenesis. The temporal expression pattern and the tissue-restricted expression pattern of CiGRP1 suggest that it has important roles in the very early stage of development and in the brain and the mesenchyme tissue specification.

Amino Acid Sequence↗

PubMed2000

Stimulatory effect of zinc-releasing calcium phosphate implant on bone formation in rabbit femora.

Although hydroxyapatite (HAP) and tricalcium phosphate (TCP) are currently used as bone graft substitutes or coatings on metallic prostheses because of their excellent biocompatibility and osteoconductivity, they do not stimulate bone formation or inhibit bone resorption. Zinc, an essential trace element in many animals, has a direct specific proliferative effect on osteoblastic cells and has a potent and selective inhibitory effect on osteoclastic bone resorption in vitro. Therefore, zinc-containing beta-tricalcium phosphate (ZnTCP) ceramics and composite ceramics of ZnTCP and HAP (ZnTCP/HAP) were implanted in the femora of New Zealand White rabbits for 4 weeks to promote bone formation. The implants were sintered ceramics with zinc contents of 0 (control), 0.063, 0.316 and 0.633 wt %. Histological and histomorphometrical investigation of the undecalcified sections revealed an increase by 51% (p =.0509) in the area of newly formed bone around the ZnTCP/HAP implants of 0. 316 Zn wt % compared with the control. Plasma zinc concentration was unchanged. An increased bone resorption on the endosteal surface was observed when ZnTCP and ZnTCP/HAP of 0.633 Zn wt % were implanted. To promote bone formation, the optimum zinc content of the calcium phosphate ceramics was therefore 0.316 wt %.

Animals↗

PubMed2000

Significance of plasma thymosin alpha1 measurements in gastric cancer patients.

Thymosin alpha1 is a cleavage product of prothymosin alpha. Expression of prothymosin alpha increases during cell proliferation. Thymosin alpha1, measurable in plasma, may be an indicator of cell proliferation especially if a cancer is present. In this report we investigated the relation between the clinical behavior of gastric cancer and the plasma thymosin alpha1 level. Plasma thymosin alpha1 was measured in 52 gastric cancer patients using a newly developed radioimmunoassay. Twenty-one tumors and lymph nodes were examined for thymosin alpha1 using immunohistochemistry. The plasma thymosin alpha1 level was higher in gastric cancer patients than in normal volunteers; and it was higher in patients with lymph node involvement than in those with negative nodes. Immunohistochemical study of thymosin alpha1 showed positivity in 52% of gastric cancers and 100% of lymph node metastasis. We concluded that a high level of plasma thymosin alpha1 suggests aggressive behavior of a gastric cancer, such as lymph node involvement.

Biomarkers, Tumor↗

PubMed2000

The transcript coding for an RNA-binding protein is localized in the anterior side of the ascidian 2-cell stage embryo.

We have cloned a putative ascidian RNA-binding protein gene, CiRGG1, which has three RNA-recognition motifs and two arginine-glycine-glycine domains. Its deduced amino acid sequence has a weak similarity to nucleolin, which is one of the known components of messenger ribonucleoproteins. Its maternal transcript is transiently accumulated into the anterior side of 2-cell stage embryos. Zygotic expression of CiRGG1 is strongest in the brain, mesenchyme and endoderm of the trunk region of the tailbud stage embryo. This mRNA is the first example of an anterior-localized molecule in the ascidian 2-cell stage embryo.

Amino Acid Sequence↗

PubMed2000

Endothelin-1 induces vascular endothelial growth factor synthesis in osteoblasts: involvement of p38 mitogen-activated protein kinase.

We previously reported that endothelin-1 (ET-1) stimulates p44/p42 mitogen-activated protein (MAP) kinase and p38 MAP kinase in osteoblast-like MC3T3-E1 cells. In the present study, we investigated the effect of ET-1 on the synthesis of vascular endothelial growth factor (VEGF) in these cells. ET-1 significantly stimulated VEGF secretion time-dependently 18 hours after the stimulation. The stimulatory effect was dose-dependent in the range between 0.1 nM and 0.1 micro;M. BQ123, an antagonist of endothelin(A) (ET(A)) receptor, inhibited the ET-1-induced VEGF secretion. The ET-1-induced VEGF secretion was suppressed by SB203580 and PD169316, inhibitors of p38 MAP kinase, but not PD98059, an inhibitor of the upstream kinase that activates p44/p42 MAP kinase. 12-O-Tetradecanoylphorbol-13-acetate (TPA), a protein kinase C (PKC)-activating phorbol ester, stimulated VEGF secretion. Calphostin C, a specific PKC inhibitor, suppressed the VEGF secretion by ET-1. TPA-induced VEGF secretion was suppressed by SB203580. Taken together, our results strongly suggest that ET-1 stimulates VEGF synthesis via ET(A) receptor in osteoblasts and that p38 MAP kinase is involved at a point downstream from PKC in the VEGF synthesis.

Animals↗

PubMed2000

p38 MAP kinase is involved in the signalling of sphingosine in osteoblasts: sphingosine inhibits prostaglandin F(2alpha)-induced phosphoinositide hydrolysis.

We previously showed that sphingosine inhibits prostaglandin F(2alpha) (PGF(2alpha))-stimulated interleukin-6 synthesis in osteoblast-like MC3T3-E1 cells. In the present study, we investigated the effect of sphingosine on phospholipase C-catalyzing phosphoinositide hydrolysis induced by PGF(2alpha) in these cells. Sphingosine inhibited the inositol phosphates formation by PGF(2alpha) or NaF, a GTP-binding protein activator. Sphingosine induced the phosphorylation of p38 mitogen-activated protein (MAP) kinase but did not affect the phosphorylation of p42/p44 MAP kinase. SB203580 and PD169316, inhibitors of p38 MAP kinase, rescued the inhibitory effect of sphingosine on the formation of inositol phosphates by PGF(2alpha) or NaF. These results indicate that sphingosine inhibits PGF(2alpha)-induced phosphoinositide hydrolysis by phospholipase C via p38 MAP kinase in osteoblasts.

Animals↗