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Biomedical subjects

H Azuma

Publications and source records attributed to H Azuma.

At least 91 records · Page 5Linked to original sources
PubMed1997

Changes in osteopontin mRNA expression during phenotypic transition of rabbit arterial smooth muscle cells.

Transition from a contractile to a synthetic phenotype appears to be an early key event during the development of intimal thickening after arterial wall injury. We examined the expression of osteopontin mRNA, proliferation, and phenotypic properties of smooth muscle cells (SMCs) in rabbit neointima after balloon denudation and in primary culture. A strong osteopontin mRNA signal was detected in the thickened intima 1 week after balloon denudation and in the surface layer of the intima 2 weeks after balloon denudation. Ki-67 immunohistochemistry showed that osteopontin mRNA expression increased when SMCs entered the proliferating phase in the intima. Rabbit arterial SMCs on type I collagen after 1 day of primary culture with growth factors, as well as freshly isolated cells, were in the G0 phase (contractile phenotype) and did not express osteopontin mRNA. After 3 days of culture, most cells entered the G1B phase (synthetic phenotype) and expressed osteopontin mRNA. In the absence of growth factors, most cells transferred to the G1A phase (intermediate phenotype) after 3 and 7 days, but did not express osteopontin mRNA. Our findings indicate that the osteopontin gene provides a marker that can be used to distinguish the phenotypic properties of vascular SMCs.

Animals↗
PubMed1997

Expression of p53 protein and p53 gene transcripts in rabbit carotid arteries after balloon denudation.

Smooth muscle cell (SMC) proliferation may be positively or negatively regulated by various factors after arterial wall injury. We investigated the hypothesis that the p53 protein may play a role in regulating SMC proliferation. We examined p53 protein expression and p53 gene transcript distribution in rabbit carotid arteries over a period of 6 weeks after balloon denudation in relation to SMC proliferation. The number of p53-positive SMCs in the neointima reached a maximum 2 weeks after balloon denudation when proliferating SMCs, decreased and were confined to the luminal surface of the intima. The p53-positive SMCs in the neointima almost paralleled the distribution of proliferating cell nuclear antigen (PCNA)-positive SMCs but not that of Ki-67-positive cells. Double immunofluorescence showed the simultaneous nuclear localization of both p53 protein and PCNA in intimal SMCs. Strong signals for p53 gene transcripts, identified by in situ hybridization, were observed in SMCs showing positive immunostaining for p53 protein. Our results indicate that p53 protein and p53 gene transcript levels increase, are closely linked to the proliferation of SMCs in the thickened intima, and play a key role in the regulation of cell proliferation during the repair process after arterial wall injury.

Animals↗
PubMed1997

Clinical significance of cytokine measurement for detection of meningitis.

Levels of interleukin-6 and tumor necrosis factor alpha were measured in cerebrospinal fluids from patients with meningitis. Interleukin-6 was increased in aseptic and bacterial meningitis, whereas tumor necrosis factor alpha was increased only in bacterial meningitis. We concluded that measurement of cytokines in cerebrospinal fluid may be useful for the rapid diagnosis of meningitis.

Case-Control Studies↗
PubMed1997

Effect of nicotine on the intimal hyperplasia after endothelial removal of the rabbit carotid artery.

1. The present experiments were designed to investigate the effect of long-term oral nicotine (10 mg/200 ml/kg/day for 7 weeks) on the intimal hyperplasia after endothelial removal of the rabbit carotid artery. 2. The plasma concentrations of nicotine were determined to be 11.7-12.5 ng/ml during the term of administration and corresponded to the plasma levels in human smokers. 3. Six weeks after the endothelial removal, light microscopy revealed a marked intimal hyperplasia. Administration of nicotine tended to accelerate the intimal hyperplasia, which was estimated by comparing the histological findings, DNA content and wet weight of the vessel wall. 4. Acetylcholine- and A23187-induced endothelium-dependent relaxations were greatly impaired in the hyperplastic artery strips. The impairment of relaxations tended to be accelerated in the nicotine group. Sodium nitroprusside-induced relaxation was not different between the control and the hyperplastic artery strips and remained unaffected in the nicotine group. 5. The concentrations of endogenous nitric oxide (NO) synthesis inhibitors, NG-monomethyl-L-arginine (L-NMMA) and asymmetrical NG,NG-dimethyl-L-arginine (ADMA) were significantly more increased in the regenerated endothelial cells compared with those in the control endothelial cells. The concentrations of L-NMMA and ADMA in the regenerated endothelial cells were significantly increased by as much as 1.3 x 10(-6) and 5.6 x 10(-7) M, respectively, in the nicotine group. 6. Immunoreactive endothelin-1 was significantly increased in the hyperplastic vessel wall (2.4 times that of the control) in 6 weeks. Administration of nicotine tended to increase the level. 7. It seems possible to assume from these results that, although, under the present experimental conditions, nicotine exhibited a tendency to accelerate the intimal hyperplasia after endothelial removal, the longer exposure to nicotine or a higher dose of the agent or both would significantly accelerate the intimal hyperplasia through the enhanced impairment of endothelium-derived relaxing factor/ NO production, which might be brought about by the enhanced increases in L-NMMA and ADMA concentrations, and the enhanced increase in endothelin-1 in the vessel wall.

Animals↗
PubMed1997

Effects of absorption enhancers on the transport of model compounds in Caco-2 cell monolayers: assessment by confocal laser scanning microscopy.

Three typical absorption enhancers, i.e., sodium caprate (Cap-Na), sodium deoxycholate (Deo-Na), and dipotassium glycyrrhizinate (Grz-K), were compared in terms of their permeability-enhancing effects on hydrophilic and hydrophobic model compounds in Caco-2 cell monolayers. The transepithelial electrical resistance (TEER) of the monolayers was reduced concentration-dependently by treatment with Cap-Na and Deo-Na, while treatment with Grz-K increased the TEER. Two patterns of TEER reduction were observed: one pattern indicated that Cap-Na had a rapid reducing effect, and another indicated that Deo-Na had a delayed reducing effect. These reductions in the TEER were accompanied by the increased transepithelial transport of two hydrophilic model compounds, sodium fluorescein (Flu-Na; MW = 376, log P = -1.52) and fluorescein isothiocyanate-dextran 4000 (FD-4; MW = 4400, log P = -2.0), and one hydrophobic model compound, rhodamine 123 hydrate (Rh123; MW = 381, log P = 1.13). The transport-enhancing effects of Cap-Na and Deo-Na on these model compounds decreased in the following order: FD-4 > Rh123 > Flu-Na, while Grz-K was found to have no effect on the transport of any of these model compounds. Confocal laser scanning microscopy (CLSM) of Caco-2 cell monolayers revealed that Cap-Na and Deo-Na enhanced the transepithelial transport of the hydrophilic model compounds via the paracellular route and that of the hydrophobic model compound via both paracellular and transcellular routes. Semiquantitative visual information obtained from CLSM images reflected the results of the transport experiment.

Biological Transport↗
PubMed1997

Nitric oxide-induced ciliary muscle relaxation during contraction with endothelin-1 is mediated through elevation of cyclic GMP.

PURPOSE: Nitric oxide (NO) relaxes ciliary smooth muscle, and endothelin-1 (ET-1) is reported to regulate ciliary muscle tone. Despite the physiological significance of nitric oxide and ET-1, very few studies have attempted to characterize the mutual modes of action of these mediators in this tissue. Thus, the present experiments were designed to investigate a possible relaxation mechanism of nitric oxide in bovine ciliary muscle that has been contracted by ET-1. METHODS: The effects of sodium nitroprusside (SNP), as a nitric oxide donor, methylene blue, as an inhibitor of guanylate cyclase, and 8-bromo-cyclic GMP on the bovine ciliary muscle contracted with ET-1 were examined. The changes in cyclic GMP level and relaxation, in response to SNP alone or in combination with 3-isobutyl-1-methylxanthine (IBMX) as a nonselective inhibitor of phosphodiesterases, were also determined. RESULTS: Sodium nitroprusside (SNP) produced a concentration-dependent relaxation, which was significantly (p < 0.005) augmented by 10(-5) M 3-isobutyl-1-methylxanthine (IBMX) and significantly (p < 0.005) attenuated by 3 x 10(-5) M methylene blue as an inhibitor of guanylate cyclase. The relaxation in response to SNP was accompanied by an increase in the cyclic 3':5' guanosine monophosphate (cyclic GMP) level, which was again significantly (p < 0.05) augmented by 10(-5) M IBMX and significantly (p < 0.005) attenuated by 3 x 10(-5) M methylene blue. The exogenously applied 8-bromo-cyclic GMP relaxed the ciliary muscle strips during the contraction caused by ET-1. CONCLUSIONS: These results lead us to assume that NO generated from SNP is closely related to cyclic GMP production via the activation of guanylate cyclase and, in turn, causes a relaxation response in the bovine ciliary muscle contracted with ET-1.

1-Methyl-3-isobutylxanthine↗
PubMed1997

Expression of Fas and Fas ligand in renal grafts with acute and chronic rejection in the rat model.

The Fas system-based rejection mechanism has not been studied well in terms of cytotoxic T cell activity in graft rejection. We investigated the Fas and Fas ligand level in renal grafts with acute and chronic rejection in a rat model using semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). Fas ligand in renal allografts was detected as early as 1 day after transplantation in an acute rejection model. It was highly expressed at day 4 and began to decline at day 6 after transplantation. In contrast, Fas ligand in normal kidneys was almost undetectable. Fas ligand in isografts was increased, but the expression level was much lower than in allografts. Interestingly, when Fas ligand expression began to decline in renal allografts, it increased in the spleens of recipients. Fas ligand expression in chronically rejecting allografts was slightly increased, but it was stronger than in isografts. In contrast to Fas ligand gene expression, Fas was constitutively expressed in isografts, allografts, and normal kidneys. However, the Fas level in renal allografts was higher than in normal kidneys. Our data demonstrated that the Fas system might play an important role in acute and chronic rejection by causing apoptosis, and the spleen may eliminate the lymphocytes strongly expressing Fas ligand after completion of the acute rejection.

Acute Disease↗
PubMed1997

The mechanism of myometrial contractions induced by endothelin-1 in rat.

Experiments were performed to characterize endothelin-1-induced contractions and the role of endothelin (ET) receptor subtypes in rat myometrium. The binding sites of [(125)I]-ET-1 were saturable with high affinity. Scatchard plot analysis revealed that ET-1 binding sites in the myometrium constituted a single population. The dissociation equilibrium constant (Kd) and the maximum binding sites (Bmax) were determined to be 48.9+/-3.0 pM and 1364.0+/-210.3 fmol/mg protein respectively. Specific [(125)I]-ET-1 binding was inhibited completely by unlabelled ET-1 and Ro 46-2005 (mixed-type ET receptor antagonist), but not fully (90.7+/-1.4%) by BQ 123 (a selective ETA receptor antagonist), and not at all by RES 701-1 (a selective ETB receptor antagonist). ET-1 induced myometrial contractions were composed of two types, an increase in resting tone and rhythmic contractions. These contractions were inhibited by BQ 123 and Ro 46-2005, but not by RES 701-1. ET-1-induced contractions were greatly reduced in Ca2+-free Krebs' solution. Nifedipine abolished the rhythmic contractions without affecting the increase in resting tone. These results suggest that ETA receptors are predominantly localized in rat myometrium and that excitation of ETA receptors evokes two types of contractions by increasing the cytoplasmic Ca2+ concentration.

Animals↗
PubMed1997

Candesartan cilexetil reduces chronic renal allograft injury in Fisher-->Lewis rats.

OBJECTIVES: To determine the effects of the angiotensin II receptor antagonist, candesartan cilexetil, on glomerular and systemic blood pressures and the development of renal injury in Lewis rat recipients of a single Fisher kidney (F334--> LEW transplantation), an established rat model of chronic renal allograft failure. DESIGN: Recent studies have shown that chronic injury of renal allografts in F334-->LEW rats may be virtually abrogated by supplying the Lewis recipients with two Fisher kidneys or, alternatively, by retaining a native kidney. These findings imply a major contribution from processes associated with nephron loss to the pathogenesis of chronic renal allograft failure, a notion supported by the observation that transplanting two kidneys also normalizes glomerular capillary pressure (PGC) in F344-->LEW rats. Thus, a pharmacological reduction in PGC, by blocking the effects of angiotensin II, should also lessen renal injury in F344-->LEW rats. MATERIALS AND METHODS: Bilaterally nephrectomized F344--> LEW rats were treated with the angiotensin II receptor blocker candesartan cilexetil (TCV-116) at 40 mg/l or with vehicle, administered in drinking water. Proteinuria and systolic blood pressure were assessed monthly, and histological studies were carried out after 24 weeks. The glomerular filtration rate and glomerular pressures were determined after 10 weeks in additional rats by clearance and micropuncture studies. RESULTS: Treatment with candesartan cilexetil lowered systemic blood pressure, normalized PGC at 10 weeks and greatly reduced proteinuria and allograft glomerulosclerosis at 24 weeks. CONCLUSIONS: These data indicate that the development of renal injury in F344-->LEW renal allografts can be prevented by the pharmacological blockade of angiotensin II receptors using candesartan cilexetil. This suggests that angiotensin-dependent processes contribute significantly to chronic injury in this model of late renal allograft failure.

Angiotensin Receptor Antagonists↗
PubMed1997

Atypical Epstein-Barr virus infection during and after intermittent FK506 therapy.

Atypical Epstein-Barr virus (EBV) infection developed in a patient under intermittent administration of FK506 (one dose in 10 days) after living-related liver transplantation. The clinical course was similar to severe chronic active EBV infection syndrome (SCAEBV), which is characterized by extremely high titers of antibody to EBV antigens. The clinical symptoms improved without graft rejection even after the cessation of FK506; however, the titers of antibody to EBV antigens remained at high levels. It was considered that: (i) even intermittent use of FK506 could influence the immune response, which then induced atypical EBV infection similar to SCAEBV; and (ii) the impaired immune response, especially to EBV antigens, remained after complete cessation of FK506.

Herpesviridae Infections↗
PubMed1997

Interferon alpha-2a therapy for disseminated intravascular coagulation in a patient with blue rubber bleb nevus syndrome. A case report.

The authors present a sixteen-year-old girl with blue rubber bleb nevus syndrome (BRBNS) associated with disseminated hemangiomas involving the skin, oral cavity, skeletal muscle, and cerebrum. Although she denied neurologic symptoms, magnetic resonance imaging of the brain demonstrated dilatated cerebral veins and the Chiari I malformation. Examination of hemostasis revealed disseminated intravascular coagulation (DIC) manifesting as Kasabach-Merritt syndrome, with the potential for life-threatening bleeding or thrombosis in the central nervous system. Since successful management of life-threatening hemangiomas with interferon alpha-2a (IFN alpha-2a) has been reported, the authors administered IFN alpha-2a with an improvement in hemostasis. These findings suggest that IFN alpha-2a therapy is beneficial for relieving the life-threatening consumptive coagulopathy associated with BRBNS.

Adolescent↗
PubMed1997

[Morphological characterization and classification of air cells in temporal bone by digital processing of CT images].

We determined the extent of pneumatization in the temporal bone and reconstructed three-dimensional structures of air cells by computer-assisted digital processing of high resolution CT images of the bone. We attempted morphological classification of temporal bone air cells by characterization of the three-dimensional structures obtained. A total of 52 ears in 33 normal subjects (18 males and 15 females; mean age 51 years) was examined. The volume of pneumatization in the temporal bone, as measured by CT, ranged from 2.08 to 20.05 ml (mean 6.40 +/- 4.09). The morphological characteristics of air cells in the three-dimensional images were examined with reference to the volume of air cells and the direct on of their growth. The three-dimensional structures were observed from four directions (lateral, supralateral, anterolateral and supramedial). Large air cells existed plentifully in all directions. Anteriorly, air cells were growing in two directions; laterally and toward the petrous apex. The growth in the latter direction was especially marked, and this contributed to the growth in the medial direction. Air cells that grew anteriorly had two directions of growth (lateral and toward the petrous apex). The directional difference in growth varied with the ear. On examining the suprainferior growth, air cells that grew large in the anterior direction were found to grow large in the suprainferior direction and those that did not grow large in the anterior direction were found contrarily to grow poorly in the suprainferior direction. With the above morphological characteristics taken into consideration, morphological classification of air cells into five types was attempted by the volume of air cells and the direction of their growth.

Adolescent↗
PubMed1997

[CT-assisted measurement of total and regional volumes of pneumatization in the temporal bone].

The total volume of air cells in the temporal bone and the regional volumes (tympanic cavity, petrous apex and mastoid antrum) were measured by using a system which we developed for the measurement of air cells by computerized digital processing of high-resolution CT images. We examined a total of 41 normal ears in 25 subjects ranging in age from 12 to 82 years (mean age 46.2). The total volume of pneumatization was approximately 4.05 +/- 1.59 ml and the volume of air cells in the tympanic cavity was 0.45 +/- 0.07 ml. Alveolation of the petrous apex was detected in 15 (36.6%) of the 41 ears, and the volume of air cells in the petrous apex was approximately 0.24 +/- 0.26 ml. The volume of air cells in the mastoid antrum was approximately 0.53 +/- 0.20 ml. The ears were divided into two groups, one with petrous alveolation (15 ears) and the other without it (26 ears). The ratios of regional pneumatization to total pneumatization were studied in the two groups. Statistically significant differences were found in the total volume and the volume of air cells in the mastoid antrum between the groups with and without petrous pneumatization (p < 0.05). The total volume of air cells did not correlate to the volumes of air cells in the tympanic cavity, mastoid cavity and petrous apex.

Adolescent↗
PubMed1997

A novel missense mutation in the endoglin gene in hereditary hemorrhagic telangiectasia.

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant disorder characterized by multisystem vascular dysplasia and recurrent hemorrhage. Recent investigation has mapped one of the responsible genes for HHT to chromosome 9q33-q34; subsequently, nine different mutations have been identified in the endoglin gene, which encodes a transforming growth factor beta (TGF-beta) binding protein, in nine unrelated families with HHT. We examined the endoglin gene in a Japanese patient with HHT and her family members. Using PCR-SSCP analysis followed by sequencing, we identified a C to A missense mutation in exon 4 which changed an Ala160 codon(GCT) to an Asp160 codon (GAT). Since this mutation destroys one of three Fnu4H 1 sites in exon 4, the Fnu4H I digestion patterns of the PCR-amplified exon 4 fragments from each family member were analyzed. In affected members, the restriction patterns were all consistent with a phenotype of HHT. PCR-amplified exon 4 fragments from 150 normal individuals were also analyzed by allele-specific oligonucleotide hybridization analysis. As a result, the mutation was not found in any of them. We conclude that the C to A mutation in exon 4 of the endoglin gene in this proband is responsible for the occurrence of HHT in this family.

Aged↗
PubMed1996

Sequential cytokine expression in renal allografts in rats immunosuppressed with maintenance cyclosporine or mycophenolate mofetil.

Although the immunosuppressive agents used clinically modulate acute rejection of organ allografts, their ability to prevent chronic rejection has been less clear. To ascertain the effects of prolonged maintenance treatment with cyclosporine (CsA) and mycophenolate mofetil, we examined sequential patterns of cytokine regulation by reverse transcriptase polymerase chain reaction in long-surviving renal allografts in treated recipients. In renal allografts in animals on long-term CsA therapy, there is important up-regulation of transforming growth factor-beta, Hsp70, and endothelin as compared with control animals. Conversely, interleukin-2 receptor, interferon-gamma, and tumor necrosis factor-alpha in kidney grafts in this group were expressed at lower levels compared with those noted in chronically rejecting grafts in control animals that had received only CsA for 10 days after transplantation. Morphologically, the long-term CsA-treated kidneys had more extensive arterial obliterative changes and glomerulosclerosis after 24 weeks than control organs; these changes can presumably be attributed to the nephrotoxic effects of this drug combined with the progressive changes of chronic rejection. In contrast, mycophenolate mofetil inhibited the production of all lymphocyte and macrophage-derived cytokines throughout the entire follow-up period. Allograft kidneys in these latter recipients showed no late morphological abnormalities. This agent may be important clinically in preventing chronic rejection.

Animals↗
PubMed1996

Blockade of T-cell costimulation prevents development of experimental chronic renal allograft rejection.

Blocking CD28-B7 T-cell costimulation by systemic administration of CTLA4Ig, a fusion protein which binds B7 molecules on the surface of antigen-presenting cells, prevents rejection and induces tolerance in experimental acute allograft rejection models. We tested the effect of CTLA4Ig therapy on the process of chronic renal allograft rejection using an established experimental transplantation model. F344 kidneys were transplanted orthotopically into bilaterally nephrectomized LEW recipients. Control animals received low dose cyclosporine for 10 days posttransplantation. Administration of a single injection of CTLA4Ig on day 2 posttransplant alone or in addition to the low dose cyclosporine protocol resulted in improvement of long-term graft survival as compared with controls. More importantly, control recipients which received cyclosporine only developed progressive proteinuria by 8-12 weeks, and morphological evidence of chronic rejection by 16-24 weeks, including widespread transplant arteriosclerosis and focal and segmental glomerulosclerosis, while animals treated with CTLA4Ig alone or in addition to cyclosporine did not. Competitive reverse transcriptase-PCR and immunohistological analysis of allografts at 8, 16, and 24 weeks showed attenuation of lymphocyte and macrophage infiltration and activation in the CTLA4Ig-treated animals, as compared with cyclosporine-alone treated controls. These data confirm that early blockade of the CD28-B7 T-cell costimulatory pathway prevents later development and evolution of chronic renal allograft rejection. Our results indicate that T-cell recognition of alloantigen is a central event in initiating the process of chronic rejection, and that strategies targeted at blocking T-cell costimulation may prove to be a valuable clinical approach to preventing development of the process.

Abatacept↗