Biomedical subjects

M Yamaguchi

Publications and source records attributed to M Yamaguchi.

At least 379 records · Page 21Linked to original sources

PubMed1999

Spontaneous rupture of a nonparasitic liver cyst complicated by intracystic hemorrhage.

a case of spontaneous rupture of simple liver cyst complicated by intracystic hemorrhage is described. This rare condition was detected in a 61-year-old man who underwent left trisegmentectomy of liver under a suspected diagnosis of cystadenocarcinoma because of elevated serum levels of carbohydrate antigen (CA) 19-9 and DUPAN 2, and the presence of an intracystic structure. The resected specimen showed a benign liver cyst with intracystic hematoma and high levels of CA19-9 and DUPAN 2 in the cystic fluid. It is suggested that cyst rupture may increase serum levels of tumor markers whose levels are high in the cystic fluid, and that repeated observations of an intracystic structure may be the most reliable method to distinguish intracystic hemorrhage from cystic neoplasm.

Antigens, Neoplasm↗

PubMed1999

Discrepancies in apparent dopamine D2 receptor occupancy between 3H-raclopride and 3H-N-methylspiperone.

Competitive inhibition of 3H-raclopride (RAC) and 3H-N-methylspiperone (NMSP) binding against haloperidol, raclopride and NMSP was measured in the mouse striatum. 3H-RAC binding was more sensitive to competitive inhibition by all three compounds compared with 3H-NMSP. For example, 0.3 mg/kg of haloperidol resulted in 95% inhibition of 3H-RAC binding, however only 60% of inhibition of 3H-NMSP binding was found at the same dose of haloperidol. The cross-inhibition experiments using non-radioactive RAC or NMSP as competitors indicated different binding sites for 3H-RAC and 3H-NMSP in mouse striatum. Specifically, about 40% of 3H-NMSP binding was not displaced by treatment with a very high dose of raclopride (3 mg/kg). The time course of inhibition of the specific binding of 3H-RAC and 3H-NMSP were measured following i.p. injection of 0.5 mg/kg of haloperidol. No significant differences in the kinetics of haloperidol inhibition were observed between two radioligands.

Animals↗

PubMed1999

Effect of vitamin K2 (menaquinone-7) in fermented soybean (natto) on bone loss in ovariectomized rats.

The effect of dietary vitamin K2 (menaquinone-7) on bone loss in ovariectomized (OVX) rats was investigated. OVX rats were freely given experimental diets containing menaquinone-4 (MK-4; 12mg/100g diet) or menaquinone-7 (MK-7; 18.1mg/100g diet) for 24 days; MK-4 and MK-7 were equal in molar concentrations. This feeding caused a remarkable increase of MK-4 and MK-7 concentrations in the serum and femur of OVX rats. OVX-induced decrease in the femoral dry weight and femoral calcium content was prevented by the feeding of dietary MK-4 or NK-7. In separate experiments, OVX rats were freely given experimental diets containing the fermented soybean (natto; including 9.4 microg MK-7/100g diet) without or with added MK-7 (37.6 microg/100g diet) for 77 days. Feeding produced a significant elevation of MK-4 and MK-7 concentrations in the serum of OVX rats. In this case, a significant increase in the femoral MK-4 content was observed but MK-7 was not detected in the femoral tissues. OVX-induced decreases in the femoral dry weight and femoral calcium content were significantly prevented by the feeding of diets containing natto with MK-7 added (37.6 microg/100g diets). This study demonstrates that the intake of dietary MK-7 has a preventive effect on bone loss caused by OVX. This effect may be partly caused by MK-4, which is formed by degradation of MK-7.

Animals↗

PubMed1999

Liver scintigraphy is useful for selecting candidates for preoperative transarterial chemoembolization among patients with hepatocellular carcinoma and chronic liver disease.

BACKGROUND: The indications for preoperative hepatic transarterial chemoembolization (TACE) have not been clarified by recent studies in patients with hepatocellular carcinoma (HCC) complicated by chronic liver diseases. The aim of the present study was to investigate which patients benefit most from preoperative TACE on the basis of hepatic functional reserve. Technetium-99m diethylenetriamine pentaacetic acid-galactosyl human serum albumin (Tc-GSA) liver scintigraphy was used to assess hepatic functional reserve before and after TACE. PATIENTS AND METHODS: Liver scintigraphy was performed before and several weeks after TACE in 64 patients with HCC complicated by chronic hepatitis or cirrhosis. The ratio of liver to heart-plus-liver radioactivity of Tc-GSA 15 minutes after injection (LHL15) was calculated. Conventional hepatic functional tests were also performed. Whether to perform hepatectomy after TACE was decided mainly on the basis of the previously reported value of LHL15 > or =0.91. RESULTS: LHL15, prothrombin time, and serum concentration of cholinesterase significantly decreased after TACE in patients with LHL15 > or =20.91 (P <0.01, P <0.05, and P <0.05, respectively). In patients with LHL15 <0.91, LHL15 and functional liver volume significantly increased after TACE (both P <0.05). Eight patients with LHL15 > or =0.91 did not undergo hepatectomy because LHL15 decreased to less than 0.91 after TACE, whereas 7 patients with LHL15 <0.91 underwent hepatectomy because LHL15 increased to more than 0.91 after TACE. Three major postoperative complications occurred in patients with LHL15 > or =0.91, and no major complications occurred in patients with LHL15 <0.91. CONCLUSIONS: The results suggest that preoperative TACE should be performed in HCC patients only when LHL15 is less than 0.91, and that preoperative TACE is not an appropriate treatment for patients with LHL15 > or =0.91 when HCC is resectable.

Adult↗

PubMed1999

Intrahepatic venovenous shunting to an accessory hepatic vein after Fontan type operation.

Because there are various types of systemic venous connections in patients with visceral heterotaxy, unanticipated abnormal systemic venous channels may pose additional problems after a Fontan type operation. We report a case of severe cyanosis caused by anomalous intrahepatic venovenous fistula to an accessory hepatic vein early after total cavopulmonary anastomosis.

Child↗

PubMed1999

Localization of neuronal-constitutive nitric oxide synthase and secretory regulation by nitric oxide in the rat submandibular and sublingual glands.

The distribution of neuronal-constitutive nitric oxide synthase (ncNOs)-positive nerve fibres was compared immunohistochemically, and the effect of NOs inhibitor and NO scavenger on the secretory response was compared functionally, in the two glands. Numerous ncNOs-positive fibres were distributed around acini in the submandibular gland but scarcely any around acini in the sublingual gland. Within the submandibular ganglion (parasympathetic), the nerve-cell bodies were strongly positive. Within the superior cervical ganglion (sympathetic), the nerve-cell bodies were negative, although some positive nerve fibres were observed. The secretory responses to the electrical stimulation of the chorda were significantly reduced by the NOs inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME, 10(-9)-10(-3) M) in a dose-dependent manner. The NO scavenger, 2-(4-carboxyphenyl)4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (carboxy-PTIO) also reduced the chorda-evoked secretion (10(-9)-10(-6) M). The submandibular secretions evoked by stimulation of the superior cervical ganglion were not affected by L-NAME or carboxy-PTIO. In the sublingual gland, neither L-NAME nor carboxy-PTIO affected chorda-evoked salivary secretion. The histochemical and functional results both suggest that NO plays an excitatory role in the regulation of parasympathetic nerve-induced salivary secretion in the rat submandibular gland, but not in the sublingual gland.

Animals↗

PubMed1999

Surgery for mitral valve disease in the pediatric age group.

OBJECTIVES: We reviewed a 20-year experience with the surgical treatment of mitral valve disease in the pediatric age group at our institution with 2 objectives: to clarify the long-term results over the last 2 decades and to evaluate the recent advances in mitral valve operation in children. METHODS: Since December 1978, 56 patients have undergone a total of 36 mitral valve repairs and 30 mitral valve replacements. Associated cardiac anomalies were present in 46 patients (82%), and concurrent repair of associated lesions was performed in 37 patients (66%). The age of the patients ranged from 3 months to 15 years (mean, 3.6 years) at mitral valve repair, and ranged from 2 months to 16 years (mean, 5.7 years) at mitral valve replacement. Mean follow-up period was 92.0 months (range, 1-235 months). RESULTS: There were 2 hospital deaths and 2 late deaths in patients who underwent mitral valve repair. Reoperation was performed in 4 patients. Three of these patients underwent mitral valve replacement because of residual mitral incompetence. No hospital deaths occurred in patients who underwent mitral valve replacement. Two late deaths occurred after mitral valve replacement. Six patients had a total of 10 episodes of prosthetic valve thrombosis. Thrombolytic therapy with urokinase was successful in all episodes without serious complications. Five patients required reoperations 49 to 141 months (mean, 78.4 months) after the initial valve replacement for relative prosthetic valve obstruction as the result of somatic growth. A valve 2 or 3 sizes larger than the original prostheses was inserted without death. Actuarial survival and freedom from cardiac events at 10 years after the operation were 87.2% and 72.7% in children who underwent mitral valve repair, and 90.3% and 67.3% for those children who underwent mitral valve replacement. CONCLUSIONS: The current risk of mitral valve operation in the pediatric age group is low, and the long-term results are satisfactory, irrespective of severe deformation of the mitral valve apparatus and associated complex cardiac anomalies.

Actuarial Analysis↗

PubMed1999

Dextran sulfate inhibits E-selectin-mediated neutrophil adhesion to endotoxin-activated vascular endothelial cells.

Effects of heparin-like glycosaminoglycans (h-GAGs) on neutrophil adhesion to endothelial cells (ECs) were investigated under physiological flow conditions using human umbilical vein ECs. Neutrophil adhesion to lipopolysaccharide-activated ECs was assayed under rotating conditions with addition of h-GAGs or monoclonal antibodies (mAbs) against selectins. Neutrophil adhesion to activated ECs under rotating conditions was suppressed completely by anti-E-selectin mAb and partially by anti-L-selectin mAb. Addition of dextran sulfate or heparin also significantly inhibited neutrophil adhesion to ECs under the same conditions. Moreover, effects of h-GAGs on neutrophil adhesion to recombinant E-selectin-coated plates were analyzed. Anti-E-selectin mAb and dextran sulfate, but not heparin, significantly inhibited neutrophil adhesion to E-selectin-coated plates. Results suggest that dextran sulfate inhibited E-selectin-mediated neutrophil adhesion to endotoxin-activated ECs under physiologic flow conditions.

Antibodies, Monoclonal↗

PubMed1999

Role of physiologic concentrations of stem cell factor in leukemic type growth of myelodysplastic CD34+ cells.

The stem cell factor (SCF: a ligand for c-kit) plays a central role in the growth of myelodysplastic (MDS) progenitor cells with leukemic type growth. In this study, the role of physiologic concentrations of SCF on the proliferation and differentiation on MDS progenitor cells was further analyzed in the presence of combined cytokines. For this purpose, marrow CD34+ cells were purified up to 94% for 12 normal individuals and 90% for 18 MDS patients, using monoclonal antibodies and immunomagnetic microspheres. The purified CD34+ cells were cultured for 14 days with saturating doses of cytokines, including recombinant human macrophage colony stimulating factor (rM-CSF), granulocyte-CSF (rG-CSF), granulocyte/macrophage-CSF (rGM-CSF), interleukin-3 (rIL-3) and rSCF. The clonal growth of MDS CD34+ cells supported by a combination of all the above cytokines was then subdivided into the two patterns of leukemic or non-leukemic. The role of various concentrations of rSCF (0, 0.5, 5, 50 and 500 ng ml(-1)), with or without the above cytokines, in proliferation and differentiation of MDS CD34+ cells was analyzed in each group. The physiologic concentration of SCF at 5 ng ml(-1) significantly increased undifferentiated 'blast cell' colonies or clusters in leukemic type growth of MDS CD34+ cells over that seen in normal CD34+ cells. SCF is present in plasma at a level of ng ml(-1). This means that progenitor cells are continuously exposed to stimulation by SCF in vivo and that MDS leukemic cells have a growth advantage over normal blasts.

Antigens, CD34↗

PubMed1999

Postoperative adjuvant adoptive immunotherapy with lymph node-LAK cells and IL-2 for pathologic stage I non-small cell lung cancer.

We conducted a clinical trial of adoptive immunotherapy with lymph node-lymphokine-activated killer (LN-LAK) cells and recombinant interleukin 2 (rIL-2) for a surgical adjuvant therapy of pathologic stage I non-small cell lung cancer. The regimen consisted of the subcutaneous administration of low-dose rIL-2 for 6 consecutive days and the transfer of ex vivo generated LAK cells from regional lymph node lymphocytes, obtained at the time of surgical operation. A group of 19 patients with primary lung cancer received the immunotherapy about 2 weeks after surgery (pulmonary lobectomy). The regimen was postoperatively well tolerated by the patients. In peripheral blood lymphocytes (PBL) obtained after the treatment, the proportion of CD3+ T cells predominantly increased with the increase of CD4+ T cell subsets. On the other hand, the proportion of CD20+ B cells decreased. Both NK and LAK activity of PBL significantly increased. However, the immunomodulatory effects did not result in a prolongation of the postoperative survival time in comparison to the postoperative survival of patients (n = 21) with surgery alone during the same period. These results suggested that the treatment with low-dose LN-LAK cells and concurrent low-dose IL-2 could, therefore, neither reduce nor eradicate minimal micrometastatic diseases.

Aged↗

PubMed1999

A clonal culture assay for human cord blood lymphohematopoietic progenitors.

We describe a two-step clonal culture assay system for human lymphohematopoietic progenitors present in umbilical cord blood which are capable of differentiation along both myeloid and B-lymphoid lineages. Human cord blood CD34+ cells were plated in methylcellulose in the presence of stem cell factor (SCF), granulocyte-colony stimulating factor (G-CSF), interleukin (IL)-7, and the murine stroma cell line, MS-5. The growing primary colonies were individually examined for their potentials to differentiate along both myeloid and B-lymphoid lineages by reculturing aliquots of the primary colonies in methylcellulose culture containing IL-3, G-CSF and erythropoietin (Epo), and on a monolayer of MS-5 in the presence of SCF and G-CSF. Approximately 10-15% of the primary colonies generated various combinations of myeloid cells and CD19+ sIgM+ cells. Subsequent studies using micromanipulated single CD34+ cells unequivocally demonstrated the clonal origin of the lymphohematopoietic progenitors. This culture system should prove valuable for elucidation of the mechanisms regulating early stages of human lymphohematopoiesis.

Animals↗

PubMed1999

Stimulatory effect of zinc acexamate administration on fracture healing of the femoral-diaphyseal tissues in rats.

The effect of zinc acexamate on fracture healing of the femoral-diaphyseal tissues in rats was investigated in vivo. Zinc acexamate (0.3 and 10.0 mg Zn/100 g body weight per day) was orally administered to rats (4 weeks old) surgically fractured the femoral diaphysis for 14 to 28 days. Calcium content and alkaline phosphatase activity in the femoral-diaphyseal tissues were significantly decreased in rats with fracture healing, while bone acid phosphatase activity and protein content were markedly increased. The administration of zinc acexamate (10.0 mg Zn/100 g) for 28 days caused a significant increase in calcium content, alkaline and acid phosphatases activities, protein and deoxyribonucleic acid (DNA) contents in the femoral-diaphyseal tissues of rats with fracture healing. With the lower dose (3.0 mg Zn/100 g), zinc compound had a partial effect on bone components. Femoral mineral density in rats with fracture healing was significantly increased by the administration of zinc acexamate (10.0 mg Zn/100 g) for 28 days. Femoral-diaphyseal zinc content was significantly decreased in rats with fracture healing. This decrease was completely restored by the administration of zinc acexamate (10.0 mg Zn/100 g) for 28 days. The present study suggests that the supplement of zinc compound stimulates fracture healing of the femoral-diaphyseal tissues in rats.

Acid Phosphatase↗

PubMed1999

Inhibitory effect of regucalcin on Ca(2+)-dependent protein kinase activity in rat brain cytosol: involvement of endogenous regucalcin.

The effect of regucalcin, a Ca(2+)-binding protein, on Ca(2+)-dependent protein kinase activity in the brain cytosol of rats with different ages (5 and 50 weeks old) was investigated. The addition of calmodulin (10 microg/ml) or dioctanoylglycerol (5 microg/ml) in the enzyme reaction mixture caused a significant increase in protein kinase activity in the presence of CaCl2 (1 mM), indicating that Ca2+ calmodulin or protein kinase C is present in the cytosol. Such an increase was completely prevented by the addition of regucalcin (10(-7) M). Moreover, regucalcin (10(-7) M) significantly inhibited cytosolic protein kinase activity without Ca2+/calmodulin or dioctanoylglycerol addition. Meanwhile, the presence of anti-regucalcin monoclonal antibody (10-50 ng/ml) in the enzyme reaction mixture caused a significant elevation of protein kinase activity, suggesting an inhibitory effect of endogenous regucalcin. Brain cytosolic protein kinase activity was significantly elevated by increasing age (50-week-old rats). Also, regucalcin (10(-7) M) significantly decreased protein kinase activity without Ca(2+) addition in the brain cytosol of aged rats. However, the effect of anti-regucalcin monoclonal antibody (50 ng/ml) in elevating protein kinase activity was not seen in the brain cytosol of aged rats. These results suggest that regucalcin has an inhibitory effect on Ca(2+)-dependent protein kinase activity in rat brain cytosol, and that the effect of endogenous regucalcin may be weakened in the brain cytosol of aged rats.

Animals↗

PubMed1999

Enhancement of lipopolysaccharide-stimulated PGE2 and IL-1beta production in gingival fibroblast cells from old rats.

The effect of aging on gingival fibroblasts in response to bacterial infection was studied. Rat gingival fibroblast (rGF) cells were cultured from gingival tissue removed from young (6 weeks old) and old (20 months old) rats. Both types of rGF cells were challenged with lipopolysaccharide (LPS) from the periodontal pathogen Campylobacter rectus. The levels of prostaglandin E2 (PGE2) and interleukin 1beta (IL-1beta) released into the cultured medium were measured by a specific radioimmunoassay. LPS stimulated PGE2 and IL-1beta production in a dose-and time-dependent manner in rGF cells from both young and old rats was seen. Production of PGE2 and IL-1beta by rGF cells from the old rats was higher than those from the young in response to LPS. This greater ability from the older rGF cells to produce PGE2 and IL-1beta was due to higher mRNA levels of cyclooxygenase 2 and IL-1beta, respectively. In contrast, cyclooxygenase-1 and IL-1beta converting enzyme gene mRNA levels remained unchanged. Because LPS-stimulated PGE2 and IL-1beta production was enhanced by in vivo cellular aging, aging of GF may affect the severity of inflammation and bone resorption by producing a large amount of PGE2 and IL-1beta in response to bacterial infection.

Aged↗

PubMed1999

Multidirectional deformation in fully congruent acetabular components.

Most clinical studies have used femoral head migration as an index of acetabular wear, but a previous study showed multiple wear vectors in 30% of retrieved acetabular components with noncongruent liners. The origin of multiple wear vectors is unclear, and it has been suggested that polyethylene creep in a noncongruent shell might influence deformation on the articular surface. We used shadowgraph and volumetric methods to evaluate the extent and direction of surface deformation of 37 retrieved polyethylene liners that were fully congruent to a single design of metal backing. The results show that multiple deformation vectors are relatively common in retrieved acetabular cups (27% in this study) and are independent of congruency between liner and metal backing, rim impingement, and backside creep. Polyethylene liners with multiple wear vectors were significantly thinner than those of cups with a single vector. The origin of multiple vectors is still unclear, but clinical and laboratory studies measuring linear wear alone without recognizing multiple vectors underestimate total in vivo volumetric wear.

Acetabulum↗

PubMed1999

Deformation of the acetabular polyethylene liner and the backside gap.

Polyethylene wear of acetabular components may cause osteolysis and aseptic loosening in total hip arthroplasty. Case reports of wear between the polyethylene liner and acetabular metal backing (backside wear) have promoted speculation on the clinical importance of debris generation at this site and the potential importance of insert conformity. We examined 90 retrieved nonconforming acetabular components from a single manufacturer. Twenty-four liners (27%) showed polyethylene deformation corresponding to screw holes on the backside surface. The location of screw-hole deformations corresponded to the direction of polyethylene deformation (wear) on the articular surface in all cases. The polyethylene liners with backside deformations were significantly thinner than the liners without deformation (P = .02). The presence of acetabular osteolysis did not significantly correlate with backside deformation, but there was a significant association between osteolysis and wear of the articular surface (P = .0004). In this implant design, backside deformation (wear) may not be due to micromotion at the interface but to the viscoelastic nature of ultra-high-molecular weight polyethylene.

Acetabulum↗

PubMed1999

Relationship between wear debris particles and polyethylene surface damage in primary total knee arthroplasty.

To study relationships between design and wear, particles were isolated from tissues around 75 failed primary total knee prostheses, and particle size and concentration were compared with the extent and distribution of wear on superior and inferior polyethylene surfaces of the corresponding implants. Twenty-four heat-pressed, posterior cruciate ligament (PCL)-retaining (group I: PCA knee), 19 non-heat-pressed, PCL-retaining with relatively flat surfaces (group II: AMK, Kinematic, Microloc, Ortholoc), 14 non-heat-pressed, PCL-retaining with relatively congruent surfaces (group III: Townley Arizona), and 18 PCL-resected implants (group IV: Insall-Burstein, Total Condylar) were evaluated. Groups III and IV had fewer particles, smaller particles, and less surface damage than groups I and II. Implants with third-body wear had relatively small debris particles; those with thinner polyethylene had more severe surface delamination and more wear between liner and metal base. Groups I and II had more rotationally asymmetric wear patterns than groups III and IV. The size and concentration of debris particles might reflect, in part, different dominant wear mechanisms among implants of different designs.

Adult↗

PubMed1999

Induction of negative regulators of haematopoiesis in human bone marrow cells by HLA-DR cross-linking.

Tumour necrosis factor-alpha (TNF alpha) is up-regulated by cross-linking of major histocompatibility complex (MHC) class II [human leucocyte antigen (HLA)-DR] antigens on monocytes. This is done by a bacterial superantigen or anti-HLA-DR monoclonal antibody (MAb). We have previously shown that HLA-DR cross-linking results in inhibition of haematopoiesis and apoptosis. TNF alpha acts as a negative regulator of haematopoiesis. Here we investigated whether HLA-DR-mediated inhibition of haematopoiesis involved TNF alpha and TNF alpha-dependent secondary signals. Anti-HLA-DR MAb H81.9 up-regulated TNF alpha, as well as transforming growth factor beta, interleukin (IL)-1beta and IL-6 in human marrow cells at the ribonucleic acid (RNA) and protein level. The effect on TNF alpha was investigated further. Up-regulation was blocked by herbimycin A, consistent with a tyrosine kinase-dependent mechanism. Up-regulation was also blunted by the soluble TNF-receptor fusion protein TNFR:Fc, suggesting an autocrine amplification loop. Following TNF alpha up-regulation, there was increased expression of Fas (CD95) and Fas-ligand (Fas-L). Up-regulation of Fas and Fas-L was blocked by TNFR:Fc. Furthermore, MAb H81.9-induced apoptosis was prevented by anti-TNF alpha MAb and by the soluble Fas receptor, Fas-Ig, providing further evidence that the TNF effect was mediated via Fas. At the transcriptional level, cross-linking of HLA-DR by MAb H81.9 affects nuclear localization of NFkappaB, which is involved in the transcription of TNF alpha. NFkappaB activity is modified by changes in cellular redox potential, and we have shown that H81.9 affects redox potential as determined by the generation of nitric oxide. These data show that HLA-DR-initiated signals are able to trigger a cascade of negative regulators of haematopoiesis. This model provides an opportunity to dissect signalling pathways that may be involved in the development of spontaneous marrow failure, and to devise interventions aimed at protecting haematopoiesis.

Antibodies, Monoclonal↗