Biomedical subjects

Y Honda

Publications and source records attributed to Y Honda.

At least 199 records · Page 11Linked to original sources

PubMed1999

BDNF attenuates retinal cell death caused by chemically induced hypoxia in rats.

PURPOSE: To investigate the neuroprotective effects of brain-derived neurotrophic factor (BDNF) against potassium cyanide (KCN)-induced retinal damage. METHODS: Rats were injected intravitreally with iodinated BDNF. Two days later, eyeballs were dissected into various parts, and the level of radioactivity in each part was measured. Retinal damage was induced by incubating rat eyeballs with 5 mM KCN. BDNF was injected intravitreally 2 days before KCN treatment, and subsequent morphometric analysis was carried out to evaluate the retinal cell damage. To elucidate the mechanisms of BDNF's neuroprotective effects, the intravitreal concentrations of amino acids and the expression of calretinin were investigated. RESULTS: Intravitreally injected BDNF was distributed evenly throughout the eyes, and the incorporation of iodinated BDNF into the retina was three times higher than in other ocular tissues. Immunohistochemical analysis demonstrated that exogenous BDNF diffused throughout the retina and was especially concentrated in the inner (INL) and outer nuclear layer. Morphometric analysis showed that the number of INL cells of the posterior area, 880 microm from the optic nerve head, was 190 +/- 4 with KCN treatment and 284 +/- 9 in control animals. Cell death appeared to be necrotic. When eyes injected with either phosphate-buffered saline (PBS) or BDNF were subjected to treatment with KCN, the number of INL cells was 186 +/- 5 in the PBS-treated controls and 253 +/- 8 in eyes treated with BDNF. Also, BDNF increased the number of calretinin-positive cells in the INL and reduced the KCN-induced elevation of intravitreal glutamate levels. CONCLUSIONS: BDNF injected intravitreally reaches the retina and attenuates the INL cell death caused by KCN-induced metabolic insult. The neuroprotective effects of BDNF are partly ascribed to the upregulation of a calcium-binding protein and the attenuation of glutamate release into the vitreous body.

Animals↗

PubMed1999

Identification of a nervous tissue-specific chondroitin sulfate proteoglycan, neurocan, in developing rat retina.

PURPOSE: To identify the expression of neurocan, a nervous tissue-specific chondroitin sulfate proteoglycan, in retina and to elucidate its changes during development. METHODS: Expressional changes of neurocan mRNAs in developing rat retinas were investigated by a semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). The localization and characterization of neurocan core proteins were also investigated with the use of Western blot analysis and immunohistochemistry. RESULTS: Gene expression of neurocan was identified in retinas by RT-PCR. Semiquantitative analysis using Southern blot analysis revealed that mRNA expression for neurocan increased at increasing postnatal stages and that it reached its peak around postnatal day 7 (P7). Immunohistochemical studies demonstrated that in differentiating rat retinal (neuroblast) cells weak neurocan immunoreactivities were observed throughout the retina on embryonal days 14 (E14) and E16. During the early postnatal period, the immunoreactivities became most conspicuous in the inner and outer plexiform layers on P7 through P14. In adult retinas, only faint immunostaining was detected. Immunoblot analysis showed two positive bands of 220- and 150-kDa core glycoproteins after treatment with chondroitinase ABC. Further immunoblot analysis revealed that the expression of these two immunolabeled variants was regulated differently during retinal development. CONCLUSIONS: The temporal and spatial regulation of expression of neurocan and its proteolytic variant during retinal development suggest that it may play a role in differentiation and neural network formation.

Animals↗

PubMed1999

Targeted delivery of anti-angiogenic agent TNP-470 using water-soluble polymer in the treatment of choroidal neovascularization.

PURPOSE: The conjugation of drugs with water-soluble polymers such as poly(vinyl alcohol) (PVA) tends to prolong the half-life of drugs and facilitate the accumulation of drugs in tissues involving neovascularization. The purpose of this study was to evaluate the effect of TNP-470-PVA conjugate on the proliferation of endothelial cells in vitro and on experimental choroidal neovascularization (CNV) in vivo. METHODS: TNP-470 was conjugated in PVA by a dimethylaminopyridine-catalyzed reaction. The effects of TNP-470-PVA and free TNP-470 on the proliferation of human umbilical vein endothelial cells (HUVECs) and bovine retinal pigment epithelial cells (BRPECs) were evaluated by the tetrazolium-based colorimetric assay (XTT assay). Experimental CNV was induced by subretinal injection of gelatin microspheres containing basic fibroblast growth factor, into rabbits. Thirty rabbits were intravenously treated either with TNP-470-PVA (n = 8), free TNP470 (n = 5), free PVA (n = 5), or saline (n = 12) daily for 3 days, 2 weeks after implantation of gelatin microspheres. Fluorescein angiography was performed to detect the area with CNV, and the evaluation was made by computerized measurement of digital images. These eyes were also examined histologically. To observe the accumulation of conjugate, 3 rabbits with CNV received rhodamine B isothiocyanate-binding PVA (RITC-PVA), and the lesion was studied 24 hours later by fluorescein microscopy. RESULTS: The TNP-470-PVA inhibited the growth of HUVECs, similar to that of free TNP-470. The BRPECs were less sensitive to TNP-470-PVA than were the HUVECs. TNP-470-PVA significantly inhibited the progression of CNV in rabbits (P = 0.001). Histologic studies at 4 weeks after treatment demonstrated that the degree of vascular formation and the number of vascular endothelial cells in the subretinal membrane of the eyes treated with TNP-470-PVA were less than those of the control eyes. RITC-PVA remained in the area with CNV 24 hours after administration. CONCLUSIONS: These results suggest that TNP-470-PVA inhibited the proliferation of HUVECs more sensitively than that of BRPECs, and the targeted delivery of TNP-470-PVA may have potential as a treatment modality for CNV.

Animals↗

PubMed1999

In vivo evaluation of platelet-endothelial interactions in retinal microcirculation of rats.

PURPOSE: This study was designed to develop a new method to evaluate the dynamics of platelets in the retinal microcirculation in vivo and to investigate quantitatively the platelet-endothelial interactions in rat retina with the use of this system. METHODS: Isolated platelet samples were labeled with carboxyfluorescein diacetate succinimidyl ester. After intravenous administration, platelet behavior in the retinal microcirculation was evaluated with a scanning laser ophthalmoscope. The images were recorded on S-VHS videotape and analyzed with a computer-assisted image analysis system. The platelet- endothelial interactions in the retinal microcirculation were also investigated with the use of lipopolysaccharide-stimulated endothelium or platelets activated with thrombin. RESULTS: Fluorescent platelets were recognized as distinct dots in the retinal microcirculation and could be traced frame by frame. The velocity of platelets in the retinal arteries, capillaries, and veins was 26.1+/-6.4, 1.6+/-0.4, and 19.9+/-8.2 mm/sec, respectively. In control rats, even the activated platelets showed minimal interaction with retinal endothelial cells. In contrast, stimulated retinal endothelium showed active platelet- endothelial interactions; many platelets were observed rolling and adhering along the major retinal veins. The interactions between platelets and stimulated endothelial cells were substantially inhibited with the injection of P-selectin monoclonal antibody. CONCLUSIONS: The present study demonstrated a new method to visualize platelet behavior in the retinal microcirculation in vivo. This method will allow quantitative evaluation of platelet dynamics and platelet- endothelial interactions in retinal pathologic conditions.

Animals↗

PubMed1999

[Birth cohort analysis of obesity in an occupational setting].

PURPOSE: The purpose of this study was to analyze the transition of body mass index (BMI) by birth cohort and to determine the relationship between BMI and high blood pressure, for the health management of workers in an industry. SUBJECTS AND METHODS: The eligible study subjects were 3,043 male workers at printing and papermaking plants who were 20 to 49 years of age in 1986 and whose annual health checkup information was available for both 1991 and 1996. First, we analyzed the transition of BMI by 5-year birth cohort. Second, we analyzed the relationship between BMI and high blood pressure (systolic blood pressure > = 140 mmHg or diastolic blood pressure > = 90 mmHg) using multiple logistic regression models. In this analysis, we excluded 596 subjects who were diagnosed as having high blood pressure in 1986 and 17 subjects whose alcohol drinking habits were unknown. Consequently, we had 2,430 study subjects. RESULTS: (1) All the birth cohorts showed that the proportion of obese subjects (BMI > = 26.4) became higher as age advanced. The proportion was higher for younger cohort. (2) By multiple logistic regression models, age at the beginning of the study, BMI, change of BMI in 5 or 10 years, and alcohol drinking habits were related to the risk of having high blood pressure. CONCLUSION: In the health management of workers, it is necessary to evaluate the risk by birth cohort. Also, we consider that we need to initiate obesity counseling before the workers become 30 years of age.

Adult↗

PubMed1999

[In vitro activity of biapenem (BIPM) against clinically isolated respiratory pathogens in 1996-1998].

The in vitro antibacterial activity of biapenem (BIPM), a new carbapenem antibiotic, was compared with those of imipenem (IPM), panipenem (PAPM), meropenem (MEPM), ceftazidime (CAZ) and piperacillin (PIPC) against 280 isolates of 9 respiratory pathogens. The MIC90s of biapenem (BIPM) for methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant Staphylococcus aureus (MRSA), Streptococcus pneumoniae, Moraxella catarrhalis, Pseudomonas aeruginosa, and Haemophilus influenzae were 0.12, 32, 0.25, 0.06, 4 and 8 micrograms/ml, respectively. In comparison with other antibiotics, the activity of biapenem (BIPM) for P. aeruginosa was as potent as meropenem (MEPM), but for H. influenzae it was slightly less than those of other antibiotics, and for other respiratory pathogens it was as potent as those of other antibiotics. The MIC90s of biapenem (BIPM) for Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae and Serratia marcescens were 0.06, 1, 1, 0.5 microgram/ml, respectively, and which were equal to or somewhat lower than those of other antibiotics. Biapenem (BIPM) showed strong activity against Gram-positive and Gram-negative pathogens, especially P. aeruginosa in general. Based on these results, biapenem (BIPM) is seemed to be highly useful antibiotic for the treatment of respiratory infections with several organism.

Bacteria↗

PubMed1999

The involvement of proteasome in myogenic differentiation of murine myocytes and human rhabdomyosarcoma cells.

The murine C2C12 myocytes terminally differentiate to myotubes in the mitogen-depletion, and a portion of the cells undergo apoptosis. In this study, a specific proteasome inhibitor lactacystin induced cell cycle withdrawal and precocious expression of myosin in C2C12 cells in mitogen-enriched medium, but these cells did not fuse to form myotubes. Mitogen-starved myocytes could not differentiate to myotubes under the proteasome inhibition. The genes for p21, MyoD, Myogenin and RB were activated, and p27 gene was repressed under the proteasome inhibition, suggesting the transcriptional regulation of these genes linked to the proteasome activity. The induction of p21 prior to MyoD may contribute to the incomplete myogenesis in the presence of lactacystin. In addition, lactacystin-treated C2C12 cells did not undergo apoptosis, while proteasome accumulated in the nuclei of apoptotic cells but not in those of myotubes during mitogen-depleted differentiation. Further, lactacystin induced similarly incomplete differentiation in human RD embryonal rhabdomyosarcoma cells. Our findings demonstrated that proteasome has an essential role in myogenesis, especially in transcriptional control of myogenic and cell cycle regulators, cell fusion forming myotubes, and apoptosis.

Acetylcysteine↗

PubMed1999

Adenovirally expressed basic fibroblast growth factor rescues photoreceptor cells in RCS rats.

PURPOSE: To evaluate the abilities of recombinant adenovirus carrying the basic fibroblast growth factor (bFGF) gene to (1) produce bFGF protein in vitro and (2) rescue retinal photoreceptors in Royal College of Surgeons (RCS) rats in vivo. METHODS: Cultured human retinal pigment epithelial cells were infected with one of the following two replication-deficient adenoviral vectors that drive inserted genes by beta-actin promoter with cytomegalovirus enhancer: AxCAJSbFGF, which expresses the human bFGF gene, and AxCAlacZ, carrying the cDNA of bacterial beta-galactosidase as a viral control. These viruses and recombinant bFGF protein were also injected into the subretinal space of RCS rats at the age of 21 days. The production of bFGF was evaluated by an immunohistochemical method in vitro and in vivo. The secretion of bFGF produced in vitro was quantified by an enzyme-linked immunosorbent assay. The thickness of the outer nuclear layer (ONL) as a marker of photoreceptor cell rescue was estimated at 2, 28, and 56 days after the injections. RESULTS: AxCAJSbFGF produced human bFGF protein effectively both in vitro and in vivo. The semiquantitative analysis of ONL thickness revealed a significant protective effect of AxCAJSbFGF and the recombinant bFGF protein injection up to 56 days after injection. CONCLUSIONS: These results demonstrate that a recombinant adenoviral vector can achieve the transfer of bFGF gene in vitro and have a protective effect for photoreceptor cells in vivo. Gene therapy with a bFGF-expressing recombinant adenoviral vector may provide a new strategy with which to target retinal degenerative diseases.

Adenoviridae↗

PubMed1999

Roles of constitutive nitric oxide synthase in postischemic rat retina.

PURPOSE: Nitric oxide is a reactive species that could be protective or destructive to the retina depending on the stage of the evolving ischemic process. This study was conducted to obtain a better understanding of the roles of constitutive nitric oxide synthase (cNOS) during reperfusion after ischemia in rat retina. METHODS: Retinal ischemia was induced for 60 minutes in Sprague-Dawley rats by ligating the optic nerve. Gene expression for endothelial and neuronal nitric oxide synthases (eNOS and nNOS) was studied by reverse transcription-polymerase chain reaction (RT-PCR). To inhibit cNOS, NG-nitro-L-arginine (L-NNA) was injected intraperitoneally four times (every 6 hours) beginning 2 hours after reperfusion, for a total dose of 80 mg/kg. Retinal damage was assessed by the rate of a- and b-wave recovery on electroretinograms and by the thickness of the retinal layers. Retinal circulation and vessel diameter were evaluated by the dye-dilution technique. RESULTS: After ischemia ended, eNOS mRNA initially decreased until 6 hours, then increased to a peak at 12 hours, and decreased progressively beyond 24 hours until the final measurement at 96 hours of reperfusion. nNOS mRNA decreased to nearly undetectable levels during the same measurement periods. L-NNA treatment enhanced reduction of a- and b-wave amplitudes and increased thinning of the inner retina in postischemic eyes. Retinal mean circulation time was markedly prolonged in L-NNA-treated postischemic eyes. Arterial mean transit times were 2.1-fold and 4.5-fold longer in L-NNA-treated postischemic eyes than in L-NNA-treated nonischemic eyes and in D-NNA-treated postischemic eyes, respectively. CONCLUSIONS: This study shows that postischemic inhibition of NOS worsens retinal damage after ischemia-reperfusion and alters postischemic retinal circulation. Nitric oxide may play an important role in protecting the retina from ischemic injury, possibly by preventing postischemic hypoperfusion.

Animals↗

PubMed1998

Immunohistochemical detection of parasite antigens in Theileria parva-infected bovine lymphocytes.

Theileria parva is the causal agent of East Coast fever (ECF), a fatal disease of cattle characterized by pyrexia, transient lymphadenopathy and panleukopenia. We have evaluated monoclonal antibodies (mAb) against three distinct antigens (p67, PIM and p32) of the parasite as immunohistological reagents for monitoring the kinetics of infection in cattle. Bovine lymphocytes were stained with the mAb at various intervals after infection in vitro and in vivo. The p67 sporozoite surface antigen was detected in only a small percentage of both, in vitro and in vivo infected cells. In contrast, expression of the polymorphic immunodominant molecule (PIM) of the parasite proved a useful indicator of infection and staining was correlated with the results of Giemsa analysis. PIM was detected from day 3 in in vitro-infected cells, but was not detected until day 5 in vivo after challenge with a 70% lethal dose of stabilized sporozoite. The p32 antigen was expressed only late in infection in vivo and its expression was associated with the development of merozoites. Less than 20% of in vitro-infected cells expressed p32. The immunohistochemical staining with anti-PIM mAb was found to be a useful tool for analysis of T. parva infection kinetics in cattle.

Animals↗

PubMed1998

Localization of glutathione and induction of glutathione synthesis-related proteins in mouse brain by low doses of gamma-rays.

First, we determined the cerebral localization of reduced glutathione (GSH) in normal mice by means of autoradiography using 99mTc-meso-hexamethyl propylene oxime. A highly specific localization of GSH in the cerebellum and hippocampus was observed. Secondly, we measured the elevation of GSH level in the brain after low-dose gamma-irradiation. The cerebral GSH levels increased soon after irradiation with 50 cGy of gamma-rays, reaching a maximum at 3 h post-treatment, then remaining significantly higher than that of the non-irradiated control until 12 h and returning to the control level by 24 h. Thirdly, we examined the induction of the activities and the mRNAs of proteins involved in the synthesis and regeneration of GSH in the brain of mice subjected to low-dose gamma-ray irradiation. The level of mRNA for gamma-glutamylcysteine synthetase was significantly increased at 0.5 h, and remained high until 2 h post-irradiation (50 cGy). The level was transiently lowered to the non-irradiated control level at 3 h and slightly increased again after 6 h post-irradiation. gamma-Glutamylcysteine synthetase activity was significantly increased 3 h after irradiation, and remained high up to 24 h post-irradiation. As for glutathione reductase, the mRNA level was increased at 0.5 h, and peaked strongly at 2 h, while the enzyme activity was significantly increased at 6 h after irradiation, and continued to increase up to 24 h. The level of mRNA for thioredoxin, which contributes to GSH biosynthesis by supplying cysteine to the de novo pathway, peaked between 0.5 h and 2 h post-irradiation, and rapidly declined thereafter. The content of thioredoxin showed a transient decrease immediately after irradiation, but was then remarkably elevated, reaching a maximum at 3 h, and thereafter declining sharply. These results indicate that the increase in endogenous GSH in mouse brain soon after low-dose gamma-ray irradiation is a consequence of the induction of GSH synthesis-related proteins and occurs via both the de novo synthesis and the regeneration pathways.

Animals↗

PubMed1998

Substrate binding subsites of chitinase from barley seeds and lysozyme from goose egg white.

Substrate binding subsites of barley chitinase and goose egg white lysozyme were comparatively investigated by kinetic analysis using N-acetylglucosamine oligosaccharide as the substrate. The enzymatic hydrolysis of hexasaccharide was monitored by HPLC, and the reaction time-course was analyzed by the mathematical model, in which six binding subsites (B, C, D, E, F, and G) and bond cleavage between sites D and E are postulated. In this model, all of the possible binding modes of substrate and products are taken into consideration assuming a rapid equilibrium in the oligosaccharide binding processes. To estimate the binding free energy changes of the subsites, time-course calculation was repeated with changing the free energy values of individual subsites, until the calculated time-course was sufficiently fitted to the experimental one. The binding free energy changes of the six binding subsites, B, C, D, E, F and G, which could give a calculated time-course best fitted to the experimental, were 0.0, -5.0, +4.1, -0.5, -3.8, and -2.0 kcal/mol for barley chitinase, and -0.5, -2.2, +4.2, -1.5, -2.6, and -2.8 kcal/mol for goose egg white lysozyme. The binding mode predicted from the p-nitrophenyl-penta-N-acetylchitopentaoside splitting pattern for each enzyme was also analyzed by the identical subsite model. Using the free energy values listed above, the binding mode distribution calculated was fitted to the experimental with a slight modification of free energy value at site G. We concluded that the binding subsite model described above reflects the substantial mechanism of substrate binding for both enzymes. The relatively large disparity in free energy value at site C between these enzymes may be due to the different secondary structures of polypeptide segments interacting with the sugar residue at site C.

Acetylglucosamine↗

PubMed1998

Type I interferon induces inhibitory 16-kD CCAAT/ enhancer binding protein (C/EBP)beta, repressing the HIV-1 long terminal repeat in macrophages: pulmonary tuberculosis alters C/EBP expression, enhancing HIV-1 replication.

We have previously observed that HIV-1 replication is suppressed in uninflamed lung and increased during tuberculosis. In vitro THP-1 cell-derived macrophages inhibited HIV-1 replication after infection with Mycobacterium tuberculosis. Suppression of HIV-1 replication was associated with inhibition of the HIV-1 long terminal repeat (LTR) and induction of ISGF-3, a type I interferon (IFN)-specific transcription factor. Repression of the HIV-1 LTR required intact CCAAT/enhancer binding protein (C/EBP) sites. THP-1 cell-derived macrophages infected with M. tuberculosis, lipopolysaccharide, or IFN-beta induced the 16-kD inhibitory C/EBPbeta isoform and coincidentally repressed HIV-1 LTR transcription. C/EBPbeta was the predominant C/EBP family member produced in THP-1 macrophages during HIV-1 LTR repression. In vivo, alveolar macrophages from uninflamed lung strongly expressed inhibitory 16-kD C/EBPbeta, but pulmonary tuberculosis abolished inhibitory C/EBPbeta expression and induced a novel C/EBP DNA binding protein. Therefore, in vitro, proinflammatory stimulation produces an IFN response inhibiting viral replication by induction of a C/EBPbeta transcriptional repressor. THP-1 cell-derived macrophages stimulated with type I IFN are similar to alveolar macrophages in the uninflamed lung in vivo. In contrast, the cellular immune response in active pulmonary tuberculosis disrupts this innate immunity, switching C/EBP expression and allowing high level viral replication.

Base Sequence↗

PubMed1998

Induction of mRNAs for glutathione synthesis-related proteins in mouse liver by low doses of gamma-rays.

We examined the elevation of the reduced form of glutathione (GSH)level and the induction of MRNAs for proteins involved in the synthesis and regeneration of GSH in the liver of mice after low-dose gamma-ray irradiation. The liver GSH level increased soon after irradiation with 50 cGy of gamma-rays, reached a maximum at around 12 h post-treatment. The mRNA of gamma-glutamylcysteine synthetase (gamma-GCS), the rate-limiting enzyme for de novo synthesis for GSH, showed a small increase that peaked at 6 h after gamma-ray irradiation at a dose of 50 cGy. Only a small increase in gamma-GCS activity was observed throughout the 24-h post-irradiation period. In the case of glutathione reductase (GR), which is involved in the regeneration of GSH from the oxidized form (GSSG), the mRNA level peaked strongly at 1 h, while the activity peaked at twice the control level 12 h after irradiation. The level of mRNA for thioredoxin (TRX), which contributes to GSH biosynthesis by supplying cysteine to the de novo pathway, peaked at 1 h and declined thereafter, while the activity peaked at 3 h and then declined sharply. These results indicate that the increase in endogenous GSH immediately following low-dose gamma-ray irradiation is predominantly due to operation of the regeneration cycle and not de novo synthesis. We also examined the dependence of mRNA induction on the gamma-ray dose.

Animals↗

PubMed1998

Inhibition of NMDA receptors and nitric oxide synthase reduces ischemic injury of the retina.

This study was performed to examine the roles of body temperature, NMDA receptors and nitric oxide (NO) synthase in post-ischemic retinal injury in rats. Cell loss in the ganglion cell layer and thinning of the inner plexiform layer were observed 7 days after ischemia. Cell loss in the ganglion cell layer but not thinning of the inner plexiform layer was reduced by hypothermia during ischemia. Intravenous injection of dizocilpine (MK-801) or Nomega-nitro-L-arginine methyl ester (L-NAME) prior to ischemia ameliorated retinal injury. These results suggest that activation of NO synthase following NMDA receptor stimulation is involved in ischemia-induced retinal injury.

Animals↗

PubMed1998

Alteration of acetohexamide reductase activities in kidney microsomes and cytosol of cadmium-treated rats.

We examined the alteration of acetohexamide reductase activities in kidney microsomes and cytosol of cadmium (Cd)-treated rats. Acetohexamide reductase activity in kidney microsomes of male rats was markedly decreased by treatment with Cd at a dose of 1.23 mg/kg body weight. However, the decreased enzyme activity was completely restored by repeated treatment with testosterone propionate. Therefore, it is reasonable to assume that the treatment with Cd indirectly affect the androgen-dependent acetohexamide reductase activity in kidney microsomes of male rats, possibly by depressing androgen production. In the case of female rats, unlike male rats, the microsomal enzyme activity was little detectable, and was unaffected by the treatment with Cd. Furthermore, Cd treatment had no significant effect on acetohexamide reductase activity in kidney cytosol of male or female rats.

Alcohol Oxidoreductases↗

PubMed1998

Angiotensin II potentiates vascular endothelial growth factor-induced angiogenic activity in retinal microcapillary endothelial cells.

Angiotensin II (Ang II) plays a role in the development of many vascular diseases. In the present study, we have investigated the effect of Ang II on vascular endothelial growth factor (VEGF) receptor expression and VEGF-induced angiogenic activity in bovine retinal microcapillary endothelial cells (BRECs). Ang II induced a significant increase of kinase domain-containing receptor/total liver kinase (KDR/Flk-1) mRNA in a time- and dose-dependent manner, with a maximal 4.3+/-0.8-fold increase after a 4-hour stimulation. Ang II increased the rate of KDR gene transcription by 5.4-fold, whereas the half-life of KDR mRNA was not increased significantly. The increase depended partially on new protein synthesis. The Ang II-induced KDR mRNA increase was inhibited by either [Sar1,Ile8]angiotensin or angiotensin type 1 receptor antagonists but was not significantly altered by angiotensin type 2 receptor antagonists. The PKC inhibitor reduced Ang II-induced KDR mRNA expression by 70+/-15%. The tyrosine kinase inhibitor reduced the Ang II- and phorbol 12-myristate 13-acetate-induced KDR mRNA increases by 35+/-8% and 44+/-26%, respectively. Ang II increased by 3.1-fold the 35S-labeled KDR/Flk-1 immunoprecipitated by a specific antibody to KDR/Flk-1. Scatchard analysis demonstrated that Ang II induced a significant increase of binding sites without changing binding affinity. Ang II enhanced VEGF-induced cell growth and tube formation. Ang II itself had no effect on cell growth, tube formation, or mRNA levels of VEGF and tms-like tyrosine kinase (Flt-1) in BRECs. These findings suggest that Ang II might potentiate VEGF-induced angiogenic activity through an increase of the VEGF receptor KDR/Flk-1.

Angiotensin II↗

PubMed1998

Cloning and characterization of the gene encoding the iron-sulfur protein of succinate dehydrogenase from Pleurotus ostreatus.

Genomic and cDNA fragments encoding the iron-sulfur protein (Ip) subunit of dehydrogenase (EC 1.3.99.1) have been cloned from the edible basidiomycetous fungus, Pleurotus ostreatus. The gene is interrupted by five introns and is predicted to encode a polypeptide of 268 amino acid residues. Sequence comparison with the Ip subunit from other species identified three conserved cysteine-rich clusters. One of these contains a critical histidine residue implicated in carboxin sensitivity in the heterobasidiomycete Ustilago maydis.

Amino Acid Sequence↗