Search PubMed⌕ Search

Biomedical subjects

M Iwamoto

Publications and source records attributed to M Iwamoto.

At least 235 records · Page 13Linked to original sources
PubMed1992

The glycosaminoglycan of recombinant human soluble thrombomodulin affects antithrombotic activity in a rat model of tissue factor-induced disseminated intravascular coagulation.

Previous studies on recombinant human soluble thrombomodulin (rsTM) from Chinese hamster ovary cells revealed that rsTM was expressed as two proteins that differed functionally in vitro due to the presence (rsTM beta) or absence (rsTM alpha) of chondroitin-4-sulfate. The current study evaluates the in vivo behavior of rsTM in rats and in a rat model of tissue factor-induced disseminated intravascular coagulation (DIC). rsTM beta was more potent than rsTM alpha for prolongation of the activated partial thromboplastin time (APTT) and their in vivo half-lives determined by ELISA were 20 min for rsTM beta and 5.0 h for rsTM alpha. Injection of a tissue factor suspension (5 mg/kg) resulted in DIC as judged by decreased platelet counts and fibrinogen concentrations, prolonged APTT, and increased fibrin and fibrinogen degradation products (FDP) levels. A bolus injection of either rsTM (0.2 mg/kg) 1 min before induction of DIC essentially neutralized effects on platelets, fibrinogen, and FDP levels, and had only a moderate effect on APTT prolongation. The dose of anticoagulant to inhibit the drop in platelet counts by 50% (ED50) was 0.2 mg/kg rsTM alpha, 0.07 mg/kg rsTM beta, and 7 U/kg heparin. The effect of increasing concentrations of rsTM and heparin on bleeding times were compared in experiments involving incision of the rat tail. Doubling of the bleeding times occurred at 5 mg/kg rsTM alpha, 3 mg/kg rsTM beta or 90 U/kg heparin. These values represent a 25-fold increase over the ED50 for rsTM alpha, 43-fold for rsTM beta and 13-fold for heparin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Inhibitory effects of beta-alanine on the vagal efferent and afferent excitatory responses of the stomach to stimulation of vagal trunk in cats.

The effects of beta-alanine on the electrically evoked vagal efferent (hexamethonium-sensitive initial excitatory response) and afferent (hexamethonium-resistant delayed excitatory response) responses of the cat stomach were studied. beta-alanine (30 to 300 micrograms/kg, i.v.) dose-dependently inhibited both the efferent and afferent response. The IC50 values of beta-alanine on the efferent and afferent response were 296 +/- 65 micrograms/kg and 128 +/- 35 microgram/kg, respectively. Maximal inhibitory effects of beta-alanine (300 micrograms/kg, i.v.) appeared about 1 hr after the injection. Glycine and taurine (100 to 10,000 micrograms/kg) did not affect these responses. Treatment with hexamethonium (10 mg/kg, i.v.) prevented the efferent response, but augmented the afferent response. The treatment with hexamethonium abolished the inhibitory effect of beta-alanine on the afferent response. Both picrotoxin (100 and 500 micrograms/kg, i.v.) and bicuculline (2000 micrograms/kg, i.v.) antagonized the inhibitory effects of beta-alanine on the vagal efferent and afferent responses of the stomach. The present experiments clearly demonstrated that beta-alanine inhibited both the vagal efferent and afferent excitatory responses of stomach to electrical stimulation of vagal trunk in cats.

Animals↗
PubMed1992

Penetrating ocular fish-hook injuries. Surgical management and long-term visual outcome.

BACKGROUND: Ocular penetrating fish-hook injuries represent a rare yet potentially devastating ocular trauma. To date, only five cases have been reported in the medical literature. The authors present five new cases with long-term follow-up. METHODS: All individuals who presented to the Wilmer Ophthalmological Institute emergency room with ocular fish-hook injuries between 1974 and 1990 were identified, and ophthalmic follow-up evaluations were performed. RESULTS: Individuals were male, between the ages of 10 and 27, with follow-up evaluation of 2.0 to 15.5 years (mean, 6.7 years). The left eye was involved in 80% and in no instance had a single hook penetrated the lid and globe simultaneously. Initial visual acuity was uniformly poor (20/200 or worse). Using specialized surgical techniques, ultimate visual outcome was excellent in 80% of cases (4 of 5 with visual acuity of 20/30 or better). One eye was enucleated because of panendophthalmitis after delayed wound closure. Similar overall results are achieved when previous reports are included in the analysis (90% with visual acuity of 20/40 or better). CONCLUSIONS: These results suggest that penetrating ocular fish-hook injuries may have an excellent long-term prognosis if prompt, appropriate surgical intervention is accomplished.

Adolescent↗
PubMed1992

Expression and characterization of kinase-active v-erbB protein using a baculovirus vector system.

The v-erbB gene is an oncogene of the avian erythroblastosis virus encoding a protein that is a truncated version of the epidermal growth factor receptor. The v-erbB protein was expressed alone or as polyhedrin-erbB fusion proteins using the Bombyx mori nuclear polyhedrosis virus vector. The expression level of the fusion protein whose polyhedrin portion consisted of only 8 amino-terminal amino acids was more than ten times higher than that of the non-fusion protein. Studies with tunicamycin showed that the recombinant v-erbB proteins were glycosylated. The recombinant protein autophosphorylated tyrosine residues, and phosphorylated a synthetic tyrosine-containing peptide and lipocortin I. These observations indicate that functional v-erbB protein can be expressed in silkworm-derived cells, and furthermore, that this system can be used for large-scale production.

Amino Acid Sequence↗
PubMed1992

[Antigen detection in the murine models of systemic candidiasis].

We compared two latex agglutination tests for serum candidal antigen in murine models of systemic infection and gastrointestinal colonization. In the intravascular-infection model, mannan detection test was positive at 2 hours after inoculation, but Cand-Tec was less sensitive than mannan detection test in this model. In the gastrointestinal colonization model followed by systemic infection in neutropenic mice, the mannan antigen test became positive after 3 weeks of colonization with increased number of Candida of the stool, and Cand-Tec became positive after 5 weeks in neutropenic mice.

Animals↗
PubMed1992

A probable case of superfecundation.

Discordant twins are of obstetrical concern because of high morbidity and mortality of either the smaller or the larger twin, or both. The discordance becomes apparent usually in the second trimester. We report a case of discordant twins diagnosed in the 10th week of gestation, which was concluded to be a case of superfecundation. The discordancy was persistent up to the 35th week of gestation, when 2 baby boys were born by cesarean section because of preeclampsia. The postnatal courses of the babies were uneventful.

Adult↗
PubMed1992

Amino acids and peptides. XVI. Synthesis of N-terminal tetrapeptide analogs of fibrin alpha-chain and their inhibitory effects on fibrinogen/thrombin clotting.

N-Terminal tetrapeptide analogs of fibrin alpha-chain were synthesized by the solution method using a new active ester, the ester of the oxime of p-nitroacetophenone, and by the solid-phase method. Their inhibitory effects on fibrinogen/thrombin clotting were examined. Of the synthetic peptides, amide analogs of Gly-Pro-Arg-Pro exhibited a more potent inhibitory effect.

Amino Acid Sequence↗
PubMed1992

[Malignant transformation of benign mixed tumor of lacrimal gland to squamous cell carcinoma 19 years after initial surgery: report of a case].

A case of malignant transformation of benign mixed tumor (pleomorphic adenoma) arising from the right lacrimal gland is reported. A 63-year-old man was referred to our clinic because of visual disturbance and protrusion of the right eye in January, 1989. His past history revealed that he had had a benign mixed tumor of the right lacrimal gland resected 19 years ago. On CT scan, an iso-density lesion homogeneously enhanced with contrast medium was found in the right orbit. This tumor was partially cystic and invaded the cranial cavity. On T1 and T2 weighted MRI, the tumor appeared as an iso-intensity area. At surgery, the tumor was subtotally resected via the combined fronto-orbital approach on February 3, 1990. Histological diagnosis of the tumor was squamous cell carcinoma, and it was construed to be a malignant transformation of mixed tumor of the lacrimal gland. Postoperatively he was placed on a course of external radiation therapy (63 Gy in total) in combination with intra-carotid Cisplatin injection therapy. The first sign of the recurrence was seen as multiple metastatic lesions in both lungs about 4 months after the surgery. In December, 1990, protrusion of the left eye and disturbance of ocular movement became progressively worse. On CT scan, recurrent metastatic tumor was seen in the left orbit and paranasal sinuses. Although additional chemotherapy and irradiation brought about a short period of symptomatic relief he succumbed to pneumonia in April 18, 1990. Metastatic squamous cell carcinoma was confirmed in the lung at autopsy.(ABSTRACT TRUNCATED AT 250 WORDS)

Carcinoma, Squamous Cell↗
PubMed1992

[Hematological values in fetal blood by cordocentesis].

Reference ranges for four hematological parameters--hemoglobin, hematocrit, white blood cell and platelet count--in each gestation were established from values for fetal blood samples obtained by cordocentesis from 72 pregnancies at 16-39 weeks gestation. These 72 fetuses turned out as normal or single malformations which should not affect fetal hematological values. Significant correlations were observed between hemoglobin, hematocrit and platelet counts and the number of weeks of gestation. No correlation was found between the white blood cell count and gestational age. Fetal anemia (hematocrit was below the lower limit of the 95% confidence interval) was found in 18 (7%) of all the fetuses that underwent cordocentesis, including nonimmune hydrops fetalis (8 cases), Rh isoimmunization (4 cases), twin-to-twin transfusion syndrome (3 cases), trisomy 18 (2 cases) and autoimmune thrombocytopenia (1 case). Of 26 hydropic fetuses, 8 (31%) were anemic. The prognosis of those fetuses depended on either the gestational age or the severity of the fetal anemia. Our results are useful in diagnosing fetal hematological disorders and to make decisions for fetal therapy.

Anemia↗
PubMed1992

[Laboratory and clinical studies on levofloxacin].

A newly developed broad-spectrum fluoroquinolone, levofloxacin (LVFX, DR-3355), was evaluated in vitro and in vivo in comparison with ciprofloxacin (CPFX), ofloxacin (OFLX) and norfloxacin (NFLX). The results were as follows. 1. Antimicrobial activity Minimal inhibitory concentrations (MICs) against 480 clinical isolates including 16 different species were determined using the microbroth dilution method. LVFX showed excellent antimicrobial activities against Gram-positive and -negative bacteria. The MIC values of LVFX for Gram-positive bacteria were superior to those of the other quinolones tested. The MIC values of LVFX for Gram-negative bacteria were comparable to those of CPFX and superior to those of OFLX and NFLX. 2. LVFX concentrations in serum and sputum LVFX was orally administered in a single dose of 200 mg to 2 patients with chronic lower respiratory tract infections, and its concentrations in serum and sputum were measured at intervals using bioassay. The peak concentrations of LVFX in serum were 1.52 and 1.24 micrograms/ml, and 84-95% of serum level were detected in sputum. From these data, it appeared that LVFX penetrate well into the lung. 3. Clinical efficacy and adverse reactions Fifteen patients with respiratory tract infections were treated with LVFX, and the overall efficacy rate was 78.6% (excellent in 3 cases, good in 8, fair in 3, poor in 0). As adverse reactions, anorexia was observed in 2 cases, diarrhea in 1 case and tremor of finger in 1 case. Although an elevation of total bilirubin in serum was observed in a case as an abnormal laboratory finding, it was mild, transient and improved rapidly after the completion of LVFX treatment.

Adult↗
PubMed1991

Effect of ticlopidine and other antithrombotics on the venous thrombosis induced by endothelial damage of jugular vein in rats.

A venous thrombosis model was produced by vessel wall damage generated by freezing a small segment of the rat jugular vein. The process of thrombus formation was investigated by electron microscopic study. Ultrastructural studies demonstrated that the initiation of thrombus formation could be deendothelialization caused by freezing of vessel. When blood flow was reestablished, platelets adhered to subendothelium within 1 min. Then platelets aggregated on the adhering platelets, and fibrin net was formed. Finally, thrombi composed predominantly of fibrin and red blood cells with platelet aggregates and leukocytes were generated. An anti-platelet agent, ticlopidine, revealed a potent antithrombotic effect in this model. Because ticlopidine decreased the number of platelet aggregates, reduced the size of aggregates, and inhibited platelet degranulation, it is conceivable that platelet aggregation in early phase of thrombus formation plays a crucial role even in venous thrombosis model. A synthetic thrombin inhibitor, argatroban, also showed a potent antithrombotic effect, but a thrombolytic agent, urokinase, was less effective. In conclusion, this model is both platelet- and coagulation-dependent.

Animals↗
PubMed1991

Reduction of basic fibroblasts growth factor receptor is coupled with terminal differentiation of chondrocytes.

Basic fibroblast growth factor (bFGF) stimulates proliferation of chondrocytes and their extracellular matrix synthesis but inhibits terminal differentiation to hypertrophic cells (Kato, Y., and Iwamoto, M., (1990) J. Biol. Chem. 265, 5903-5909). In the present study, we examined changes in bFGF binding during chondrocyte cytodifferentiation. In cultures of pelleted growth plate chondrocytes, binding of 125I-bFGF to 140-kDa receptors was observed during the mitotic and matrix-forming stages but decreased to a very low level as chondrocytes became hypertrophic. Scatchard plot analysis showed that the decrease in binding of bFGF was due to a decrease in the number not in the affinity of the receptor. The loss of bFGF receptor was associated with a decrease in biological responses to bFGF. On the other hand, the binding of transforming growth factor-beta and epidermal growth factor was constant throughout all stages of growth plate chondrocytes. A rapid decrease in bFGF binding was not observed with articular chondrocytes or bFGF-exposed growth plate chondrocytes, perhaps because they scarcely underwent terminal differentiation. A decrease in bFGF binding associated with terminal differentiation in situ was also demonstrated by examination of sequential slices of growth plates. These observations suggest that rapid reduction in bFGF receptor is a special event during terminal differentiation.

Alkaline Phosphatase↗
PubMed1991

The ultrastructural defect in conjunctiva from a case of recessive dystrophic epidermolysis bullosa.

The predominant feature in the several forms of epidermolysis bullosa is the formation of cutaneous bullous lesions arising after minimal mechanical trauma. Ocular involvement has been noted as a complication. To our knowledge to date, only four investigators have correlated clinical eye disease with light microscopic findings. Ultrastructure of the ocular lesions has not been described previously. We present four cases of recessive dystrophic epidermolysis bullosa emphasizing their associated ocular complications. Diagnosis was confirmed by skin biopsy specimen and in one patient by demonstrating light and electron microscopic findings in eyelid skin. This tissue exhibited ultrastructural recessive cutaneous lesions; namely, bullous separation occurring below the basal lamina and absence of anchoring fibrils in both bullous and nonbullous areas. By electron microscopy, the conjunctiva in this patient exhibited an absence of clear anchoring fibrils that were numerous in control tissue. This defect may increase the susceptibility of the conjunctiva to minor mechanical trauma, resulting in the bullous and cicatricial changes seen clinically.

Aged↗
PubMed1991

Monoclonal IgGs from an autoimmune MRL/Mp-lpr/lpr mouse induce an interleukin-3-dependent myeloid cell line to produce tumor necrosis factor alpha and interleukin-6.

We previously reported that two IgG mAbs, 1D11 and 1G10, derived from an autoimmune MRL/Mp-lpr/lpr(MRL/l) mouse, induced IL-3 synthesis in the IL-3-dependent myeloid cell line, FDC-P2/185-4. In this study, we found that these mAbs induced TNF-alpha and IL-6 production in FDC-P2/185-4 cells. Both TNF-alpha and IL-6 were secreted rapidly within 1 hr after the addition of mAb to the cells. Increases of TNF-alpha and IL-6 mRNA were also observed in FDC-P2/185-4 cells stimulated with MRL/l-derived mAb. The anti-Fc gamma RII mAb 2.4G2 suppressed TNF-alpha and IL-6 production induced by these mAbs. Our results suggest that some IgGs of MRL/l mice may have the capacity to induce cytokine synthesis in Fc gamma R-bearing cells.

Animals↗
PubMed1991

Serum IgG from CBA/K1Jms-lprcg/lprcg mice induces interleukin 3 in an interleukin-3-dependent cell line--possible correlation with lymphadenopathy.

Serum IgG of CBA-K1Jms-lprcg/lprcg (lprcg/lprcg) mice with spontaneous systemic lymphadenopathy supported the proliferation of an IL-3-dependent cell line, FDC-P2/185-4. The lprcg/lprcg IgG induced IL-3 synthesis in FDC-P2/185-4 cells, and cells grew by an autocrine mechanism. There was virtually no time lag between the appearance of lymphadenopathy and an increase of IL-3-inducing activity in the sera. We have previously shown that serum IgG from other autoimmune mice with lymphadenopathy, MRL/Mp-lpr/lpr(MRL/lpr) and C3H/HeJ-gld/gld(C3H/gld), also induces IL-3 synthesis and cell growth in FDC-P2/185-4 cells. Furthermore, neither F1 (lprcg/+) mice between lprcg/lprcg and CBA(-)+/+ nor those (lpr-gld) between C3H-lpr/lpr and C3H/gld showed such IL-3-inducing activity, while those (lprcg-gld) between lprcg/lprcg and C3H/gld showed activity much lower than that of their parental strains but significantly higher than that of normal CBA(-)+/+ mice. This result is consistent with the incidence and degree of lymphadenopathy in these F1 mice. Our results suggest that expression of IgG(s) with cytokine-inducing activity might be controlled by these mutant genes, lpr, gld, and lprcg, and might be related to lymphadenopathy in these mice.

Animals↗
PubMed1991

Retinoic acid treatment induces type X collagen gene expression in cultured chick chondrocytes.

The vitamin A derivative retinoic acid (RA) is widely thought to be involved in cartilage development, but its precise roles and mechanisms of action in this complex process remain unclear. We have tested the hypothesis that RA is involved in chondrocyte maturation during endochondral ossification and, in particular, is an inducer of maturation-associated traits such as type X collagen and alkaline phosphatase. Immature chondrocytes isolated from the caudal region of Day 19 chick embryo sterna were seeded in secondary monolayer cultures and treated either with a high dose (100 nM) or with physiological doses (10-35 nM) of RA for up to 3 days. We found that after an initial lag of about 24 h, physiological doses of RA indeed induced type X collagen gene expression in the immature cells. This induction was not accompanied by obvious changes in expression of the type II collagen and large aggregating proteoglycan core protein genes. As revealed by immunocytochemistry, 30-35% of the cells in cultures treated with RA for 3 days were engaged in type X collagen production. Interestingly, these cells were relatively similar in size to chondrocytes in which no type X collagen was detected, suggesting that chondrocytes can initiate type X collagen production independent of cell hypertrophy. RA treatment also led to increased alkaline phosphatase activity occurring as early as 24 h after the start of treatment. The data in this study indicate that RA may have a role in endochondral ossification as an inducer/promoter of maturation-associated traits during chondrocyte maturation.

Alkaline Phosphatase↗