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Biomedical subjects

H Ishida

Publications and source records attributed to H Ishida.

At least 505 records · Page 28Linked to original sources
PubMed1995

Tri-iodothyronine (T3) and dexamethasone interact to modulate osteoprogenitor cell differentiation in fetal rat calvaria cell cultures.

We investigated the role of 3,5,3'-tri-iodothyronine (T3) in regulating differentiation of osteoprogenitor cells and also studied the effects of the glucocorticoid hormone dexamethasone (Dex) on the T3-induced effects on osteoprogenitor populations. This was done by determining the effects of either hormone alone, or of combinations of the two hormones, on the number of bone nodules formed in long-term cultures of rat calvaria cells. In this system, Dex has been shown to increase bone nodule formation, the maximal effective dose being 10 nM (Bellows et al. Endocrinology 121: 1985-1992; 1987). In standard culture medium containing 15% fetal bovine serum FBS), low concentrations of T3 (0.001-0.1 nM) had no effect on the number of bone nodules, while higher concentrations of 1-100 nM inhibited. However, in culture medium containing 10 nM Dex, the lower concentrations of T3 markedly increased the number of nodules. Short term pulse experiments with these low concentrations of T3 in the presence of Dex indicated that stimulation of nodule formation occurred only when T3 was present prior to confluency. Higher concentrations of T3 (1-100 nM) decreased nodule number whether or not Dex was added. We then cultured cells in medium containing FBS from which T3 and T4 were removed by treatment with AG-1 chi-10 resin. In both + or - Dex conditions, bone nodule formulation was increased 1.5 to 2-fold in T3, T4-depleted medium when compared with cultures maintained in standard culture medium.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1995

Prefabricated vascularized periosteal grafts using fascial flap transfers.

The purpose of this study was to demonstrate the feasibility of prefabricated vascularized periosteal grafts using fascial flap transfers. Fifty rats were divided into two (Group A, underwent periosteal wrapping, and Group B underwent fascial wrapping). Fascial flap from the medical leg, which were nourished by the saphenous artery and vein, were used for all grafts. In Group A, the fascia was transferred onto the proximal tibial periosteum. Two weeks postoperatively, the elevated fascioperiosteal flap was wrapped around a 4-mm hydroxapatite cube. In Group B, the fascial flap was immediately wrapped around the hydroxyapatite cube. In both groups, the hydroxapatite-wrapped cube was transferred to the inguinal region. Three days postoperatively, five rats from group A were sacrificed. On histologic examination, these five showed no necrosis of the fascioperiosteal flap and no bone formation. The remaining 45 rats were sacrificed 5 weeks postoperatively. Microangiography was performed on five rats in Group A, revealing neovascularization of the hydroxyapatite. On histologic examination, new bone formation was confirmed in 15 of the remaining 20 rats in Group A, and in three of the 20 rats in Group B. These experiments demonstrated that the prefabricated vascularized periosteal graft, which has good osteogenic capacity, could be carried out using a fascial flap transfer.

Angiography↗
PubMed1995

Oligonucleotide-mediated modulation of mammalian gene expression.

The notion that oligonucleotides can modulate gene-specific expression was established more than a decade ago. Recent advances in molecular genetics have broadened the armamentarium used to manipulate gene expression in biological systems including triplex DNA, antisense RNA/DNA, and ribozymes (catalytic RNA). These oligonucleotides demonstrated important early application to the elucidation of cellular signaling pathways. More recently, studies with these agents have probed their utility as potential therapeutic agents, especially in the realm of cancer. With the implementation of gene therapy in early clinical trials, oligonucleotide-mediated suppression of gene expression has emerged as an important strategy for gene therapy. This review will discuss the current knowledge in this field, focusing on the biology of triplex DNA, antisense oligonucleotides, and ribozymes.

Animals↗
PubMed1995

Treatment of nevus of Ota with autologous-cultured epithelium grafting combined with dermabrasion.

Nevus of Ota is an anomaly of the dermal melanocytes, which lies primarily in the deep dermis. It causes discoloration of the face and induces a remarkable disfigurement to the patients. This report demonstrates the favorable results of 3 male patients treated with autologous-cultured epithelium grafting combined with dermabrasion. The lesions on the cheek, forehead, and temple were dermabraded to the deep dermal layer. The cultured epithelium obtained from preauricular skin or medial upper arm were grafted on the wounds. The grafts took well, and most of the grafted site healed after 1 week. Facial appearances improved remarkably. There was minimal scar formation and minimal recurrence of nevus cell. After long-term follow-up, the grafted sites resembled the adjacent normal face skin in terms of appearance and texture.

Adult↗
PubMed1995

The effects of endothelin-1 on flap necrosis.

In reconstructive surgery, flap necrosis is a major obstacle. The vasospasm in microvascular circulation can be one of the causes of flap necrosis. The vascular endothelium has an important role in the regulation of vascular tone by producing vasodilating and vasoconstricting factors. Endothelin-1, a 21-amino acid polypeptide isolated from the vascular endothelium, is reported to be one of the most potent vasoconstrictors. The purpose of this study was to determine the significance of endothelin-1 on flap necrosis using a rat skin flap. First, we introduced into the experiment endothelin-1 and ETA receptor antagonists, FR139317, then we tried to determine the time course changes of endothelin-1 levels in the flap. Endothelin-1 antagonist had no effect on survival length, although endothelin-1 injection clearly reduced survival length. The combined treatment of antagonist and injection suppressed the effect of endothelin-1 in reducing survival length. Endothelin-1 levels in the flap base significantly increased from 6 hours, and its levels in the flap periphery presented no remarkable changes. These results may suggest that endothelin-1, especially that produced in the flap base, exerts a major effect on flap microcirculation.

Animals↗
PubMed1995

Partial soleus muscle island flap transfer using minor pedicles from the posterior tibial vessels.

A new method for partial soleus muscle island flap transfer using minor pedicles from the posterior tibial vessels was designed and executed. A portion of the soleus muscle body that was slightly wider than the defect was harvested with minor pedicles. The muscle flap was transposed by turning it over or by creating an island flap. Skin grafts were applied to the exposed muscle. This new type of muscle flap was applied to six patients with a pretibial skin defect at the lower third of the leg. It was used for treatment of an open fracture with an associated skin defect in four patients, chronic osteomyelitis in one patient, and a recurrent stasis ulcer in one patient. In all patients the transferred muscle flap survived completely.

Aged↗
PubMed1995

Mechanisms of 4-quinolone resistance in quinolone-resistant and methicillin-resistant Staphylococcus aureus isolates from Japan and China.

Ninety-two and 33 methicillin-resistant Staphylococcus aureus (MRSA) strains were isolated in Japan and China respectively. They were categorised as ofloxacin-susceptible (MIC < 12.5 mg/L), moderately (MIC 12.5-25 mg/L) or highly (MIC > or = 50 mg/L) ofloxacin-resistant. 4-Quinolone concentrations required to inhibit purified DNA gyrase from the moderately and highly quinolone-resistant MRSA were at least 20 times higher than those required to inhibit the equivalent enzyme from quinolone-susceptible strains. Reconstitution assays demonstrated that the 4-quinolone-resistant MRSA had a mutation in subunit A of DNA gyrase. A portion of the gyrA gene from amino acids codons 40-115 was sequenced. Four moderately resistant and seven highly resistant MRSA contained a Ser-->Leu substitution at amino acid 84; one moderately and one highly resistant MRSA and one moderately resistant methicillin-susceptible S. aureus (MSSA) strain contained a Glu-->Lys substitution at amino acid 88. Eight MRSA, including one quinolone-susceptible strain and one MSSA contained a silent mutation at amino acid 86. Uptake of ofloxacin in moderately resistant strains was almost the same in the presence or absence of carbonyl cyanide m-chlorophenylhydrazone (CCCP), whereas in highly resistant strains, uptake increased when CCCP was added. Restriction fragment length analysis of the norA gene with the restriction endonuclease SfcI showed a mutation of nucleotide position 1085 in all MRSA strains tested except for one highly quinolone-resistant strain. Thus the mechanisms of 4-quinolone-resistance in these MRSA isolates involved alterations in both DNA gyrase and antimicrobial uptake and efflux.

Anti-Infective Agents↗
PubMed1995

The urinary concentration of sialic acid is increased in non-insulin-dependent diabetic patients with microangiopathy: a possible useful marker for diabetic microangiopathy.

In order to investigate the relationship between urinary excretion of sialic acid and the severity of diabetic microangiopathy, urinary levels of sialic acid were determined in patients with non-insulin-dependent diabetes mellitus. The urinary molar ratio of sialic acid to creatinine in the diabetic patients was significantly higher than in the healthy controls (p < 0.01). Moreover, the urinary ratio was found to be gradually increased with the degree of diabetic microangiopathy. Urine molar ratio of sialic acid to creatinine in patients with proliferative diabetic retinopathy was significantly higher than in patients without retinopathy (p < 0.01). Urinary excretion in patients with macroproteinuria was also significantly higher than in patients without nephropathy (p < 0.01). Since urinary levels of sialic acid are proportionally increased with the severity of diabetic microangiopathy, the measurement of urinary sialic acid could become a useful biochemical means to monitor the degree of diabetic microangiopathy.

Adult↗
PubMed1995

Comparative study of endotoxin-induced hypotension in kininogen-deficient rats with that in normal rats.

1. The aim of this study was to clarify the role of endogenous bradykinin (BK) in the hypotensive response induced by lipopolysaccharide (LPS) by comparing the degree of hypotension caused by LPS in a strain of specific pathogen-free (SPF) Brown Norway (B/N), kininogen-deficient mutant Katholiek rats with that of B/N normal Kitasato rats. 2. The dose-dependent hypotensive responses caused by intravenous injection of BK (1-100 nmol kg-1) or platelet-activating factor (PAF, 0.003-1 microgram kg-1), were not different in the two strains of rats used. However, there was a strong difference in the hypotensive response induced by LPS in kininogen-deficient and normal rats; in normal rats the hypotensive response was composed of two phases (15 min and 70-80 min after LPS injection), but in kininogen-deficient rats LPS caused a delayed (second phase), but not an acute (first phase) hypotension. 3. We demonstrate that Hoe 140 (1 mg kg-1, i.v.) is a potent, selective, and long-lasting antagonist of the hypotensive effects of BK. Hoe 140 diminished the hypotension caused by LPS in normal rats to the level observed in kininogen-deficient rats, but had no effect on the hypotension caused by LPS in kininogen-deficient rats. 4. TCV309 (0.1 mg kg-1, i.v.) selectively inhibited the hypotension caused by repetitive injection of PAF for up to 180 min. Pretreatment with TCV309 caused a near complete inhibition of the LPS-induced hypotension in kininogen-deficient and normal B/N rats. 5. In the normal rats, dexamethasone (0.5 mg kg-1, i.p.) inhibited the second phase of the hypotension induced by LPS, but not the first phase of the hypotension. 6. A small amount of BK (0.1 nmol kg-1) potentiated the hypotensive action of PAF (0.01 microg kg-1),when they were injected simultaneously.7. In conclusion, we demonstrate that formation of endogenous BK contributes primarily to the acute,but not to the delayed hypotension afforded by endotoxin in the rat. In contrast, formation of endogenous PAF contributes to both the acute and the delayed hypotension afforded by endotoxin in vivo.

Amino Acid Sequence↗
PubMed1995

Cloning of multidrug resistance gene pqrA from Proteus vulgaris.

The multiple antibiotic resistance gene pqrA was cloned from the chromosomal DNA of a clinical isolate of Proteus vulgaris 881051 into Escherichia coli KY2563. The MICs of quinolones tetracycline, cephalosporin, and chloramphenicol for transformant strain DNS7020 were from 8 to 32 times higher than those for the parent strain, KY2563. The level of expression of outer membrane protein F (OmpF) by DNS7020 was lower than that of KY2563 but not as low as that of an OmpF-deficient control strain. The 1.4-kb fragment containing the pqrA gene had an open reading frame encoding a polypeptide of 122 amino acid residues with a molecular weight of about 14,000, which was consistent with the experimental value identified by the Maxicell method. The putative PqrA polypeptide showed significant amino acid sequence similarity to the E. coli proteins SoxS and MarA. These polypeptides are strongly conserved in predicted helix-turn-helix DNA binding domains. The MarA protein, which is responsible for multiple antibiotic resistance in E. coli, also decreases OmpF expression. Moreover, the SoxS protein, which is characterized as a superoxide response regulon of E. coli, has also been shown to increase resistance to many structurally unrelated antibiotics. The soxS gene increases superoxide dismutase levels in addition to decreasing OmpF expression. The expression level of superoxide dismutase with DNS7020 was about 1.5 times higher than that with KY2563. These findings suggest that the pqrA gene in P. vulgaris confers multidrug resistance in a way similar to that of the soxS and marA genes in E. coli.

Amino Acid Sequence↗
PubMed1995

Interleukin 10 reduces mortality from severe peritonitis in mice.

Interleukin 10 (IL-10) is known to suppress the induction of proinflammatory cytokines such as tumor necrosis factor (TNF) and IL-1 and is itself induced by monocytes and macrophages during sepsis. We studied the therapeutic efficacy of IL-10 by testing its effect on the survival rate in the murine cecal ligation-and-puncture (CLP) model. Administration of 1 microgram or more of recombinant murine IL-10 6 h after induction of sepsis decreased lethality in septic mice significantly and also suppressed the elevation of circulating TNF after sepsis. However, treatment with the same dose of IL-10 simultaneously or 6 h before induction of CLP had no effect on survival, and treatment with anti-TNF antibody after induction of CLP had no effect on the survival rate. These data suggest that cytokine modulation with IL-10 is a potential candidate for the treatment of sepsis and sepsis-related multiple organ failure.

Animals↗
PubMed1995

Infrequent involvement of mutations on neurofibromatosis type 1, H-ras, K-ras and N-ras in urothelial tumors.

The neurofibromatosis type 1 (NF1) gene is considered a tumor-suppressor gene whose product acts upstream of ras. The ras gene is an oncogene very commonly detected in human cancers and consists of three families, H-ras, K-ras and N-ras. These genes are converted to active oncogenes by point mutations in codon 12, 13, or 61. Examination was made of the mutations of these genes in 39 urothelial malignant tumors (31 bladder cancer, 6 renal pelvic tumor, and 2 ureter tumors) using polymerase chain reaction single-stranded conformation polymorphism and direct sequencing methods. Three of 39 (7.7%) cases showed mobility shifts in the ras family gene but no point mutations in NF1 and N-ras genes could be detected. Mutations were found in 1 case in H-ras at codon 13 (GGT-GTT/GGT) and K-ras at codon 12 in 2 cases (GGT-GCT/GGT, GGT-GTT/GGT). All 3 cases had progressed far beyond grade 2 and stage pT2. It follows from the above that NF1 and ras gene mutations are infrequent in the pathogenesis of urothelial tumors.

Base Sequence↗
PubMed1995

Human glioma-derived interleukin-10 inhibits antitumor immune responses in vitro.

Intracranial malignant gliomas are sequestered from the immune system yet are associated with broad suppression of host immunocompetence. Immune system dysfunction in patients with gliomas seems to be related to inhibitory mediators produced by glioma cells. We investigated the physiological roles of glioma-derived interleukin (IL)-10 in Class II expression of monocytes, cytokine secretion from lymphocytes, and T cell proliferation in vitro. We could detect the messenger ribonucleic acid transcript of IL-10 in four gliomas by the reverse-transcribed polymerase chain reaction. Glioma-derived IL-10 greatly down-regulated human lymphocyte antigens-DR expression on monocytes. The inhibitory effect of IL-10 on interferon-gamma and tumor necrosis factor-alpha was neutralized by the anti-IL-10 monoclonal antibody; however, the inhibitory effect on IL-2 was not neutralized. Next, supernatants of glioma cells remarkably suppressed T cell proliferation in a dose-dependent fashion; however, this inhibitory effect was not restored by adding anti-IL-10 monoclonal antibodies. The supernatant also inhibited the allocytolytic activity of lymphocytes that were not neutralized by anti-IL-10 monoclonal antibody. IL-10 plays an important role in cytokine synthesis; nevertheless, impaired T cell responsiveness cannot be solely explained by glioma-derived IL-10.

Brain Neoplasms↗
PubMed1995

Hypoglycemic and hypolipidemic effect of chitosan in normal and neonatal streptozotocin-induced diabetic mice.

The hypoglycemic and hypolipidemic effect of chitosan was investigated in normal and neonatal streptozotocin-induced diabetic (NSZ) mice, one of the animal models of lean type non-insulin-dependent diabetes mellitus (NIDDM) with hypoinsulinaemia. Chitosan (5% food admixture) reduced the blood glucose (P < 0.01), cholesterol (P < 0.01) and triglyceride (P < 0.01) of normal mice after 4 weeks, and also significantly lowered the blood glucose (P < 0.05) and cholesterol (P < 0.05) of NSZ mice under the same conditions. But these parameters of KK-Ay mice, which exhibit obese type NIDDM with hyperinsulinaemia, were not affected by chitosan administration. It is concluded that chitosan would be useful for the treatment of lean type NIDDM with hypoinsulinaemia.

Animals↗
PubMed1995

Differential effects of an alpha 1-blocker (doxazosin) on diurnal blood pressure variation in dipper and non-dipper type hypertension.

A study was conducted to determine whether sympathetic nerve activity, one of the main regulators of blood pressure, is involved in high blood pressure in the night-time and morning. Twenty-seven untreated hypertensive subjects, in whom hypertension was diagnosed by ambulatory blood pressure (ABP) measurement, who showed a 24 h systolic ABP value over 140 mmHg and/or 24 h diastolic ABP over 90 mmHg were recruited. They also showed a night-time systolic ABP value of over 130 mmHg and/or a night-time diastolic ABP of over 80 mmHg. They were divided into two groups: "dippers (D)" whose night-time ambulatory blood pressure fell by more than 10% of the day-time blood pressure, and "non-dippers (ND)" in whom this phenomenon was absent. We examined the effect of a long-acting alpha 1-blocker (doxazosin) on diurnal blood pressure variation in these subjects with essential hypertension. Baseline casual blood pressure and 24 h systolic ABP were not significantly different between the two groups. However, both night-time and morning ABP in ND were higher than those in D. Administration of doxazosin (mean 73 +/- 13 (SE) d) significantly decreased casual blood pressure, and 24 h, day-time, night-time and morning systolic ABP in the whole cohort. When subjects were divided into D and ND, the day-time and morning systolic ABP decreased significantly after doxazosin treatment in both groups, whereas the night-time systolic ABP decreased significantly only in ND but not in D. These results suggest that sympathetic nerve activity involved in elevating blood pressure during the night may differ between D and ND.

Adrenergic alpha-Antagonists↗
PubMed1995

Physiological concentrations of retinoic acid suppress the osteoblastic differentiation of fetal rat calvaria cells in vitro.

The effects of retinoic acid (RA) on osteoblastic differentiation and activity were studied in fetal rat calvaria cells cultured for up to 24 days. Fetal bovine serum used for the experiments was treated with an anion-exchange resin to remove endogenous RA. The depletion of RA in the treated serum was confirmed by high-performance liquid chromatography and tritiated RA tracing. Under the culture conditions employed, the continuous presence of RA for 14 days at 10(-9) mol/l or higher decreased both alkaline phosphatase (ALP) activity on day 12 and the number of bone nodules on day 14 in a dose-dependent manner. Short-term (24 h) exposure to RA at 10(-8) mol/l, which is a physiological concentration, decreased and increased the levels of ALP and osteopontin mRNA on day 6, respectively. Retinoic acid at 10(-8) mol/l also increased the level of osteocalcin mRNA on day 12. However, these effects were not obvious at later stages (days 18 and 24). At a high concentration (10(-6) mol/l), RA increased the level of osteopontin mRNA on day 6 and decreased the levels of ALP and osteocalcin mRNA irrespective of culture period. These results suggest that, at physiological concentrations, RA suppresses the differentiation of osteoprogenitor cells and regulates osteoblastic functions.

Alkaline Phosphatase↗