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Biomedical subjects

W Cao

Publications and source records attributed to W Cao.

At least 109 records · Page 6Linked to original sources
PubMed1998

Effects of tetramethylpyrazine, a Chinese medicine, on plasma endothelin-1 levels during acute pulmonary hypoxia in anesthetized dogs.

Our study was designed to elucidate the effects of tetramethylpyrazine (TMP), a Chinese medicine, on plasma endothelin-1 (ET-1) levels in dogs with acute pulmonary alveolar hypoxia. Anesthetized dogs were used under artificial ventilation with room air or a hypoxic gas mixture (10% O2 and 90% N2) (n = 10) for 60 min. Effects of TMP (80 mg/kg) were studied by i.v. injection of TMP before exposure to hypoxia (n = 8). Mean pulmonary arterial pressure (PAPm), systemic arterial pressure (SAPm), right atrial pressure (RAP), pulmonary capillary wedge pressure (PCWP), cardiac output (CO), and heart rate (HR) were measured. The pulmonary vascular resistance (PVR) was calculated by the equation of (PAPm-PCWP) x 8/CO. Plasma ET-1 levels were determined in the abdominal aorta and pulmonary artery by RIA. The effects of TMP on PAP and plasma ET-1 level were evaluated by using percent increase in PAPm and the change of Da-pET (delta ET) before and after hypoxia. Both PAPm and PVR were significantly elevated 5 min after acute hypoxia over a period of 60 min, whereas CO and PCWP did not change. Plasma ET-1 levels in the abdominal aorta and Da-pET showed a significant increase. Administration of TMP significantly decreased the hypoxia-induced increase in the PAPm, PVR, and delta ET. These results suggest that TMP could be a useful therapeutic agent in the treatment of pulmonary hypertension induced by acute hypoxia through decrease of plasma ET-1 levels.

Anesthesia, General↗
PubMed1998

Identification of a glucocorticoid response element in the rat beta2-adrenergic receptor gene.

Regulation of beta2-adrenergic receptor (beta2AR) levels by glucocorticoids is a physiologically important mechanism for altering beta2AR responsiveness. Glucocorticoids increase beta2AR density by increasing the rate of beta2AR gene transcription, but the cis-elements involved have not been well characterized. We now show that one of six potential glucocorticoid response elements (GREs) in the 5'-flanking region of the rat beta2AR gene is necessary for glucocorticoid-dependent stimulation of receptor gene expression. Using a nested set of deletion fragments of the rat beta2AR gene 5'-flanking region fused to a luciferase reporter gene, glucocorticoid-dependent induction of reporter gene expression in HepG2 cells was localized to a region between positions -643 and -152, relative to the transcription initiation site. In electrophoretic mobility shift assays, a double-stranded oligonucleotide incorporating a near-consensus GRE from this region (positions -379 to -365) formed complexes with the human recombinant glucocorticoid receptor, as well as with nuclear protein from dexamethasone-treated HepG2 cells. Mutation of a single base within this GRE sequence greatly diminished interaction of the mutated oligonucleotide with the human recombinant glucocorticoid receptor. The functional activity of the GRE was characterized using a luciferase reporter construct driven by a minimal thymidine kinase promoter. In HepG2 cells transfected with constructs containing the GRE, dexamethasone increased reporter gene expression approximately 3-fold, whereas a dexamethasone effect was not observed with constructs lacking the GRE. Taken together, these findings show that a GRE located at positions -379 to -365 in the 5'-flanking region of the rat beta2AR gene mediates glucocorticoid stimulation of beta2AR gene transcription.

Animals↗
PubMed1998

Genetic analysis of N-acetyltransferase polymorphism in a Chinese population.

AIM: To study the genetic basis of N-acetylatransferase polymorphism in Chinese. METHODS: Genotypes in 120 healthy Han volunteers from 19 provinces of China were assayed. The 3 common mutant alleles (M1, M2, M3) and one normal wild-type (WT) allele of the N-acetyltransferase (NAT2) gene were detected by allele-specific polymerase chain reaction technique. RESULTS: The NAT2 allele frequencies in 120 Chinese (WT = 0.625, M1 = 0.0458, M2 = 0.188, M3 = 0.142) were different (P < 0.01). The NAT2 genotype distribution for all detected combinations of NAT2 alleles in 120 Chinese subjects was consisitent with Hardy-Weinberg equilibrium (chi 2 = 7.27, nu = 8, 0.7 > P > 0.5). Fifty subjects (41.7%) were homozygous wildtypes, 50 subjects (41.7%) were heterozygous mutants, and 20 subjects (16.7%) were homozygous mutants. CONCLUSION: The lower frequency of mutant M1 allele compared with that of Caucasians explains the low frequency of slow acylators in Chinese.

Acetyltransferases↗
PubMed1998

Pharmacokinetics of theophylline metabolites in 8 Chinese patients.

AIM: To study theophylline metabolites pharmacokinetics in patients after a therapeutic dose. METHODS: Eight adult patients with mild bronchial asthma and normal liver function were infused aminophylline intravenously (6.6 mumol.kg-1). The plasma concentrations of theophylline and its 4 metabolites: 1,3-dimethyluric acid (DMUA), 3-methylxanthine (3-MX), 1-methyluric acid (MUA), and the intermediate 1-methylxanthine (1-MX) were monitored by HPLC throughout 24 h. RESULTS: The plasma concentration of DMUA was the highest one among the 4 metabolites. 3-MX showed the slowest elimination rate. The plasma concentration of 1-MX throughout a 24-h period showed that there was a picking up of 1-MX (from 0.04 mumol.L-1 to 1.05 mumol.L-1) in the next morning. CONCLUSION: The formation of DMUA was the main metabolites. During night there was an accumulation of 1-MX.

Adult↗
PubMed1998

[Mutation of p53 gene in human fetal gastric mucosal cells by sterigmatocystin in vitro].

Cell culture, flow cytometry and silver-staining PCR-SSCP methods were used to explore the effects of sterigmatocystin(ST) (1 mg/L and 3 mg/L) on carcinogenesis and mutation of tumor suppressor gene p53 in human fetal gastric mucosal cells in vitro. Four weeks after treated with ST, the cells showed vigorous growth and malignant transformation foci. Twenty-four weeks after ST treatment, the cells could form cellular colonies in soft agar(the mean colony number was 15 and 17 perdish for ST 1 mg/L and 3 mg/L groups respectively). Flow cytometric analysis showed that both proliferation indexes (PI) and the cellular DNA contents of ST treated cells were much higher than those of normal control. The DNA contents of ST treated cells were in DNA aneuploid range. Mutant p53 protein expression was also significantly higher in ST treated cells. Silver-staining PCR-SSCP analysis showed that abnormal electrophoretic migration bands could be seen at exon 8 of p53 gene in ST-treated groups 22 weeks after ST treatment, while no abnormal bands were found in control group. Thus, the results further confirmed the carcinogenic effects of ST on human fetal gastricmucosal cells.

Aneuploidy↗
PubMed1998

[The expression of plasminogen activator inhibitor-1 (PAI-1) gene in human astrocytomas].

OBJECTIVE: To investigate the expression of PAI-1 gene and its clinical significance in human astrocytomas. METHODS: The mRNA and protein expression of PAI-1 were examined with Northern blot hybridization and ABC immunohistochemical methods in 36 cases of astrocytomas. The correlation between PAI-1 expression with clinicopathologic factors were studied. RESULTS: All astrocytoma tissues expressed 3.0 kb and 2.2 kb transcripts of PAI-1 mRNA. The PAI-1 mRNA level in high grade astrocytomas were considerably higher than that in low grade astrocytomas (P < 0.01). Detectable levels of PAI-1 mRNA were not found in normal brain tissues. PAI-1 mRNA expression was positively correlated with necrosis (r = 0.51, P < 0.01), micro-blood vessel quantity (r = 0.33, P < 0.01) and brain edema (r = 0.27, P < 0.01) respectively. There was no correlation between PAI-1 mRNA expression and tumor size, sex or age of patients. Immunohistochemical staining for PAI-1 showed the distribution of PAI-1 protein was mainly in tumor cells of high grade astrocytomas, particularly in abundant areas of vascular proliferation and in remnant tumor cells surrounding necrotic foci, whereas it was only weakly expressed in low grade astrocytomas. CONCLUSION: The expression of PAI-1 gene was closely associated with grade, necrosis, angiogenesis and brain edema, which may provide a molecular marker for determining the malignant degree of astrocytoma.

Astrocytoma↗
PubMed1998

Induction of c-fos and c-jun mRNA expression by basic fibroblast growth factor in cultured rat Müller cells.

PURPOSE: Exogenous basic fibroblast growth factor (bFGF) induces bFGF gene expression in cultured rat Müller cells. To elucidate the mechanism that links exogenous bFGF to transcriptional regulation of bFGF gene expression in these cells, the authors examined mRNA expression of the proto-oncogenes c-fos and c-jun in response to exogenous bFGF in cultured rat Müller cells. METHODS: Müller cells from 1- to 3-day-old Sprague-Dawley rats were isolated and cultured in essential modified Eagle's medium + 10% fetal calf serum. Cultured cells were identified by immunocytochemical analysis using antibodies against vimentin, carbonic anhydrase C, and glutamine synthetase. Cells of passages 1 through 4 were treated with bFGF (0.01, 0.1, 1, 10, and 100 ng/ml), either the protein kinase C (PKC) inhibitors H-7 (30 microM) and GF109203X (1 microM) or the PKC activator phorbol 12-myristate 13-acetate (PMA; 1, 10, 100, 500 nM), and either adenylate cyclase activator forskolin (5 microM) or adenylate cyclase inhibitor SQ22536 (100 microM). Northern blot analysis was performed to determine the mRNA expression of c-fos, c-jun, and bFGF. RESULTS: Addition of bFGF to culture medium induced c-fos and c-jun mRNA expression in a dose- and time-dependent manner. Induction of c-fos mRNA was observed as early as 10 minutes (9.6-fold) after exposure to bFGF at a dose of 10 ng/ml. It reached a maximum of 17.4-fold by 30 minutes. A rapid decline of c-fos mRNA level was observed after 45 minutes of bFGF treatment. The temporal pattern of c-jun gene expression was similar to that of c-fos, whereas a maximum induction of c-jun mRNA (8.2-fold) was seen after 45 minutes of treatment. Induction of c-fos and c-jun gene expression started at a bFGF concentration of 0.1 ng/ml. It reached peak levels of 15-fold for c-fos and 7.6-fold for c-jun mRNA at 10 ng/ml. A dose-dependent upregulation of c-fos and c-jun gene expression by the PKC activator PMA was also observed. A maximum induction was seen at 100 nM PMA. The induction of c-fos and c-jun gene expression by bFGF or by PMA was blocked by the PKC inhibitors H-7 (30 microM) or GF109203X (1 microM). SQ22536 (100 microM), an adenylate cyclase inhibitor, did not inhibit bFGF-induced c-fos and c-jun gene expression, whereas forskolin (5 microM), an adenylate cyclase activator, upregulated the expression. CONCLUSIONS: These results indicate that exogenous bFGF induces c-fos and c-jun gene expression in cultured rat Müller cells through PKC activation. The proto-oncogenes c-fos and c-jun may play a role in the regulation of bFGF gene expression in response to exogenous bFGF in retinal Müller cells. These findings provide further insight into the roles of Müller cells and exogenous bFGF in protecting against photoreceptor degeneration.

Adenylyl Cyclases↗
PubMed1998

Prostaglandin E2 induces vascular endothelial growth factor and basic fibroblast growth factor mRNA expression in cultured rat Müller cells.

PURPOSE: To investigate the induction of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) gene expression by prostaglandin E2 (PGE2) in cultured rat Müller cells and to study the mechanism of the induction. METHODS: Müller cells were obtained from neonatal Sprague-Dawley rat retinas and cultured in essential modified Eagle's medium supplemented with 10% fetal calf serum for up to four passages. Cells were treated with PGE2, protein kinase A (PKA) inhibitors H-89 or SQ 22536, protein kinase C (PKC) inhibitors calphostin C or GF 109203X, PKC activator phorbol 12-myristate 13-acetate (PMA), or the PKA activator forskolin. Northern blot analysis was performed to determine the levels of VEGF and bFGF mRNA. RESULTS: PGE2 induced VEGF and bFGF mRNA expression in a dose- and time-dependent manner. VEGF and bFGF mRNA reached peaks of 2- and 3.5-fold at 10 microM PGE2. No further increases were observed at 100 microM PGE2. When treated with 10 microM PGE2, the increases in VEGF and bFGF mRNA reached maximum by 2 hours, then slowly declined toward the control level within 24 hours of PGE2 treatment. The inductions of VEGF and bFGF mRNA expression by PGE2 were blocked by the specific PKA inhibitors H-89 (30 microM) or SQ 22536 (500 microM, 1000 microM). Forskolin (10 microM), a cyclic adenosine monophosphate activator, also stimulated VEGF and bFGF mRNA expression. However, the effects of forskolin and PGE2 on VEGF gene expression were not additive, whereas forskolin enhanced the effect of PGE2 on bFGF mRNA expression. The specific PKC inhibitors, GF 109203X (2 microM) and calphostin C (1 microM), did not inhibit PGE2-induced VEGF gene expression, whereas PGE2-induced bFGF expression was blocked by the PKC inhibitor GF 109203X. In addition, downregulation of PKC by PMA (0.8 microM) treatment did not block the induction of VEGF gene expression, whereas it did inhibit the induction of bFGF mRNA expression. CONCLUSIONS: These results indicate that PGE2 stimulates VEGF and bFGF mRNA expression in cultured rat Müller cells. The induction of VEGF seems to occur through activation of the PKA pathway, whereas that of bFGF occurs through PKA and PKC activation. These findings raise the possibility that endogenous PGE2 stimulates VEGF and bFGF mRNA expression in Müller cells in vivo under conditions in which PGE2 production is increased, such as in injury.

Animals↗
PubMed1997

Nucleotide sequences and gene organization of TaqI endonuclease isoschizomers from Thermus sp. SM32 and Thermus filiformis Tok6A1.

Eight TaqI isoschizomer genes, two from Yellowstone National Park, one from Japan, two from New Zealand, two from Portugal, and one from the Azores (1000 miles west of Portugal), were PCR-amplified and sequenced. Sequence alignment of isoschizomers isolated from close geographical locations shows identical or almost identical protein sequences, while isoschizomers from distant sites demonstrate considerable diversity, ranging from 54 to 75% in amino acid identity. Accordingly, these isoschizomers were arranged into four geographical groups, i.e., USA as represented by Thermus aquaticus YT1, Japan by Thermus thermophilus HB8, New Zealand by Thermus filiformis Tok6A1, Portugal by Thermus sp. SM32. The complete ORFs of two new representative genes, tfiTok6A1I and tsp32IR, were obtained by bubble PCR. Unlike M . TaqI-R.TaqI and M . TthHB8I-R . TthHB8I which exhibit an unusual 13-codon overlap, the methylase and endonuclease genes are each separated by 15 nucleotides in the TfiTok6A1I and Tsp32IR restriction-modification systems. Phylogenetic analysis suggests that initially TfiTok6A1I diverged from a common ancestor, then Tsp32IR branched out, and finally TaqI and TthHB8I diverged from each other during evolution.

Amino Acid Sequence↗
PubMed1997

Viral persistent infection affects both transcriptional and posttranscriptional regulation of neuron-specific molecule GAP43.

Recently, we reported that in vitro and in vivo persistent infection of neurons by lymphocytic choriomeningitis virus (LCMV) downregulated GAP43 expression, a protein involved in neuronal plasticity associated with learning and memory. Here, we investigated the transcriptional and posttranscriptional events involved. Persistent LCMV infection of PC12 cells (PC12Pi) caused reduced levels of GAP43 steady-state mRNA when compared to uninfected PC12 cells. In addition, an increase in the steady-state levels of GAP43 mRNA observed in PC12 cells in response to nerve growth factor (NGF) was abrogated in PC12Pi cells. Nuclear run-on analysis revealed that the rate of GAP43 transcription was reduced threefold in PC12Pi cells compared to uninfected PC12 cells. Moreover, analysis of the half-life of GAP43 mRNA indicated that NGF-mediated stabilization of GAP43 transcripts was significantly diminished in PC12Pi cells. Treatment of PC12Pi cells with basic fibroblast growth factor, dibutyryl cyclic AMP, and 12-o-tetradecanoyl-phorbol-13-acetate, a potent activator of protein kinase C, did not increase the GAP43 mRNA steady-state level, suggesting that LCMV infection interferes with a step downstream from protein kinases A and C in the NGF signal transduction pathway.

Animals↗
PubMed1997

Mechanical injury increases bFGF and CNTF mRNA expression in the mouse retina.

We characterized the survival-factor response of the normal mouse retina to mechanical injury by examining the expression of mRNAs for basic fibroblast growth factor (bFGF), ciliary neurotrophic factor (CNTF), and their receptors, FGF receptor-1 (FGFR-1) and CNTF receptor alpha (CNTFR-alpha). The retina was injured by making an incision through the choroid and retinal pigment epithelium that penetrated the subretinal space of each eye of an adult BALB/c mouse. Retinas were taken 6 hr, 12 hr, 1, 2, 4, 7, 10 and 16 days post-injury. Control animals were without injury. Northern blot analysis was performed to determine bFGF, CNTF and their receptor mRNA levels. A significant increase in bFGF and CNTF mRNAs was observed after injury, along with an increase in glial fibrillary acidic protein (GFAP) expression. More than 2-fold of upregulation of bFGF mRNA was seen as early as 6 hr after injury. This increase reached a maximum of more than 5-fold at day 2 post-injury and then declined slowly, and was still about 2.5-fold of the control level by day 16. Expression of CNTF showed a small increase of about 1.6-fold at 6 hr after injury. The upregulation reached a peak level of about 2.7-fold at day 4 after injury, then declined to control level by day 16. There was only a very small increase in FGFR-1 at 6, 12 and 24 hr after injury, and no significant increases in FGFR-1 at time points longer than 1 day post-injury. Expression of GFAP followed a time course similar to that of bFGF. We conclude that mechanical injury induces bFGF, CNTF, and GFAP expression in the mouse retina with time courses similar to the upregulation of these molecules in rat retina. Compared to the upregulation in rat retina, however, the injury-induced upregulation of bFGF and GFAP is much less in the mouse retina. In addition, there was only a very small induction of FGFR-1 expression in the mouse retina. These findings may explain, at least in part, the lack of injury-induced photoreceptor protection in the mouse retina.

Animals↗
PubMed1997

Risk factors for human cysticercosis morbidity: a population-based case-control study.

A population-based case-control study to determine social and behavioural risk factors for Taenia solium cysticercosis in humans was carried out in a rural area. Shandong province, China. Forty-eight cases with cysticercosis were ascertained through a prevalence survey conducted among 7281 persons in 1993. For each case, four controls residing in the same village and matched for age and sex were randomly selected. Information regarding demographic, social and behavioural factors was collected during house visits through interviews and direct observation. Risk factors strongly associated with human cysticercosis included poor personal hygiene, being unable to recognize cysticerci-containing meat, poor pig-raising practices and a history of passing tapeworm proglottides. The results indicate that health education in combination with chemotherapy for taeniasis is required for the control of cysticercosis in humans.

Adolescent↗
PubMed1997

CBF beta-SMMHC, expressed in M4Eo AML, reduced CBF DNA-binding and inhibited the G1 to S cell cycle transition at the restriction point in myeloid and lymphoid cells.

CBF beta-SMMHC is expressed from the inv(16) chromosome in M4Eo AML. Mice lacking CBF subunits or expressing the CBF beta-SMMHC or AML1-ETO oncoproteins failed to develop definitive hematopoiesis. To investigate these effects on hematopoiesis, we expressed CBF beta-SMMHC from the metallothionein promoter, in both 32D cl3 myeloid cells and Ba/F3 B-lymphoid cells. Addition of zinc increased CBF beta-SMMHC levels more than tenfold, with higher levels evident in Ba/F3 lines. Levels obtained in 32D cl3 cells were similar to those of endogenous CBF beta. Indirect immunofluorescence revealed zinc-inducible speckled, nuclear staining in Ba/F3 cells and diffuse nuclear staining in 32D cl3 cells. CBF beta-SMMHC reduced endogenous CBF DNA-binding fivefold in both cell types, increased cell generation time 1.9-fold, on average, in 32D cl3 cells and 1.5-fold in Ba/ F3 cells and decreased tritiated thymidine incorporation into DNA correspondingly. CBF beta-SMMHC increased the proportion of cells in G1 1.7-fold, on average, in 32D cl3 and Ba/F3 cells, and decreased the proportion of cells in S phase by a similar degree. CBF beta-SMMHC induced a marked increase in hypophosphorylated Rb, but did not alter IL-3 Receptor alpha or beta subunit levels. Neither apoptosis nor 32D differentiation was induced by zinc in IL-3 in these lines. Induction of CBF beta-SMMHC in 32D cl3 cells did not inhibit their differentiation to neutrophils or their expression of myeloperoxidase mRNA in G-CSF, and did not produce an eosinophilic phenotype. Additional, proliferative genetic changes in M4eo AMLs might potentiate inhibition of differentiation by CBF beta-SMMHC by allowing its increased expression.

Animals↗
PubMed1997

[Effects of calcium channel blockers and calmodulin inhibitors on the secretion of endothelin-1 in cultured endothelial cells].

OBJECTIVE: The study is to investigate the effects of calcium channel blockers and calmodulin inhibitors on the secretion of endothelin-1 (ET-1) in cultured endothelial cells from human umbilical veins. RESULTS: Results showed that calcium channel blockers verapamil (5.5 x 10(-6) mol/L, 5.5 x 10(-5) mol/L), diltiazen (2.4 x 10(-4) mol/L) and calmodulin inhibitors chlorpromazine (3.1 x 10(-5) mol/L, 3.1 x 10(-4) mol/L), berbamine (1.6 x 10(-5) mol/L, 1.6 x 10(-4) mol/L) significantly decreased medium ET-1 levels in cultured endothelial cells. CONCLUSION: It was also indicated that extracellular calcium influx and calmodulin activity were necessary to the secretion of ET-1. In addition, nitroglycerine (2.2 x 10(-3) mol/L) remarkably reduced medium ET-1 levels in cultured endothelial cells, which suggested that nitric oxide might inhibit the secretion of ET-1.

Alkaloids↗
PubMed1997

[Molecular characterization of genetic defects in hemophilia in Shanghai].

OBJECTIVE: To detect gene mutations in hemophilia A in Shanghai. METHODS: PCR, denaturing gradient gel electrophoresis (DGGE) and DNA sequencing were used. Fifty Chinese cases of hemophilia A without intron 22 inversion, including 24 severe, 9 moderate and 17 mild cases, were screened. Genomic DNA was amplified using GC-clamped primers covering all the exons and flanking intron regions, excluding the middle portion of extron 14 encoding the B domain, but including the thrombin cleavage sites at AA740 and 1689. The amplified GC-clamped PCR fragments were then electrophoresed on DGGE. The abnormal bands were sequenced. RESULTS: Eleven different mutations were identified, including 5 nonsense mutations, 5 missense mutations and one small deletion. Among them, 3 mutations, 466Lys (AAG)-Thr (ACG), 719Tyr (TAC)-Stop (TAG) and 312Ile (ATC)-xxC have not been reported before. CONCLUSION: Apart from intron 22 inversion, most gene mutations in hemophilia A were point mutations resulted from single base substitution. Generally the genetic defects correspond to the clinical manifestations.

Asian People↗
PubMed1997

[Investigation on absorption edge and Ep, Eg of tetragonal crystal system SBN].

In this paper, the station of the absorption edge of Sr0.63 Ba0.37 Nb2O6 single Crystal is measured with experimental studies. The absorption coefficient is calculated with transimitting curve. The absorption edge below 3.5eV is attributable to indirect transition by studing the alpha1/2-hv curve. The phonon energy Ep and the energy gap Eg are ascertained.

English Abstract↗
PubMed1997

Induction of basic fibroblast growth factor mRNA by basic fibroblast growth factor in Müller cells.

PURPOSE: To investigate the induction of basic fibroblast growth factor (bFGF) gene expression in cultured rat Müller cells by bFGF and to study the mechanism of induction. METHODS: Müller cells from 1- to 3-day-old Sprague-Dawley rats were isolated and cultured with Dulbecco's modified Eagle's medium with 10% fetal calf serum. Cultured cells were identified by immunocytochemistry using antibodies against vimentin, carbonic anhydrase II, and glutamine synthetase. Cells of passages 1 through 4 were treated with bFGF, the protein kinase C (PKC) inhibitor, H-7; calphostin C, or the PKC activator, PMA; and protein kinase A (PKA) inhibitor, H-89; as well as the adenylate cylase activator, forskolin; or the adenylate cyclase inhibitor, SQ22536. Northern blot analysis was performed to determine the mRNA expression of bFGF, ciliary neurotrophic factor (CNTF) and brain-derived neurotrophic factor (BDNF). RESULTS: Addition of bFGF to culture medium induced bFGF gene expression in a dose- and time-dependent manner. Induction of bFCF mRNA started at a bFGF concentration of 0.1 ng/ml. The bFGF mRNA level was elevated by 2-fold at 1 ng/ml of bFGF, 2.8-fold at 5 ng/ml, and reached a peak of 4-fold at 10 ng/ml and 3.7-fold at 50 ng/ml. At 10 ng/ml of bFGF, induction of bFGF mRNA was observed as early as 2 hours (2-fold) after treatment. The bFGF mRNA level continued to increase to 3.7-fold by 4 hours, and reached a maximum of 4.4-fold by 8 hours. A slow decline of the bFGF mRNA level was observed after 8 hours of bFGF treatment (3.5-fold by 12 hours, and 3-fold by 24 hours). This induction of bFGF gene expression was blocked by PKC inhibitors H-7 (30 microM). The PKC activator PMA (0.1 microM) also upregulated bFGF gene expression, but the effects of bFGF and PMA were not additive. An adenylate cyclase inhibitor, SQ22536 (100 microM), did not inhibit bFGF-induced bFGF gene expression. Although forskolin (5 microM), an adenylate cyclase activator, also upregulated the level of bFGF mRNA, the effects of forskolin and bFGF were additive. In addition, no inhibitory effect on bFGF-induced expression of bFGF mRNA was found using H-89 (1 microM). Exogenous bFGF did not alter the mRNA levels of CNTF and BDNF. CONCLUSIONS: These results indicate that bFGF induces bFGF gene expression in cultured rat Müller cells through PKC activation. The authors' findings raise the possibility that Müller cells in vivo also respond to available bFGF (for example, that released from the endogenous reservoirs in the case of injury) or to exogenous bFGF by producing more bFGF, which could in turn promote photoreceptor survival.

Animals↗