Biomedical subjects

H Masuda

Publications and source records attributed to H Masuda.

At least 181 records · Page 10Linked to original sources

PubMed1998

[High dose chemotherapy with peripheral blood stem cell transplantation (PBSCT) For advanced testicular cancer].

Five patients with metastatic testicular cancer of advanced extent according to the Indiana University criteria were enrolled into this study. All tumors were non-pretreated non-seminomas. Initially all patients were treated with standard dose etoposide, ifosfamide and cisplatin (VIP) regimen. The response of two cycles of VIP was evaluated by tumor markers and diagnostic imagings. Two of the five patients showed a good response to VIP and subsequently achieved a pathological complete response (pCR) following surgical resection of residual masses after 3 or 5 courses of VIP. However, they suffered from severe myelosuppression and underwent peripheral blood stem cell transplantation (PBSCT) following the final course of VIP. The remaining three patients unlikely to be cured by VIP underwent chemotherapy consisting of high dose ICE:ifosfamide (6-10 g/m2 over 4days) carboplatin (1,500 mg/m2 over 4 days), etoposide (1,600-2,400 mg/m2 over 4 days) combined with PBSCT. This regimen resulted in one partial response (PR) with marker-negative and two PR with marker-positive. Residual masses were removed in all three patients and viable tumor cells were found in two. Of the five patients enrolled, four patients (80%) remain disease-free with minimal follow-up of 20 months, and the remaining one died of cancer 10 months after PBSCT. No serious side effects or complications were encountered. This study shows that standard dose induction therapy of VIP followed by early salvage chemotherapy of high dose ICE with PBSCT is well tolerated and effective in the treatment of advanced poor-risk testicular cancer.

Adult↗

PubMed1998

[Late results of emergency operation in acute type A dissection].

77 cases of acute type A dissection underwent emergency operation during 5 years were studied. There were 37 men and 40 women, and 58 cases in type I, 19 cases in type II on DeBakey type. The grafting for the aorta including the tear was basically performed under selective brain perfusion and deep hypothermic circulatory arrest. The overall hospital mortality rate was 24.7%. However, it was 14% after using GRF glue. The overall actuarial survival rate for 58 patients who survived operation was 87% at 5 years after surgery. Late remnant false lumen-related complications were recognized in four patients (6.9%). For two of them, subsequent operations were performed. Another two patients died of rupture of remnant false lumen during observation. Aortic valve regurgitation was recognized preoperatively in 13 patients. None of them required subsequent operation in late phase. Results and countermeasure for late remnant false lumen-related and aortic valve-related complications were investigated.

Acute Disease↗

PubMed1998

The somatostatin analog, octreotide, inhibits in vitro outgrowth of smooth muscle cells from canine coronary and carotid atherosclerotic plaque tissues.

Restenosis is caused by excessive neointima formation resulting from smooth muscle cell (SMC) proliferation and migration from the arterial media into the subendothelial space, stimulated by growth factors. A long-acting somatostatin analog, octreotide, activates protein tyrosine phosphatases and can inhibit the stimulatory effects of growth factors. In this study, we evaluated the effect of octreotide on SMC outgrowth from in vitro explants of both coronary and carotid arterial tissues in a canine endothelium-injury model. After 6 days of culture, SMC grew out of 33.3% and 58.3% of the explants from the injured canine carotid and coronary arterial tissues, respectively. In contrast, SMC outgrowth was not observed from any of the explants from normal canine carotid arterial tissue. Octreotide completely inhibited SMC outgrowth from injured canine carotid arterial tissue at a concentration of 10(-6) M. This agent also inhibited SMC outgrowth from injured canine coronary arterial tissue by 57% and 71% of the control value at concentrations of 10(-8) M and 10(-6) M, respectively. We conclude that our explant cell-culture model may prove to be valuable for assessing the effect of agents designed to reduce intimal proliferation, and that the use of the somatostatin analog octreotide in clinical settings may modify the high incidence of restenosis after coronary interventions by reducing SMC proliferation.

Animals↗

PubMed1998

Congenital bicuspid aortic valve: analysis of 63 surgical cases.

BACKGROUND AND AIMS OF THE STUDY: This study reports the clinicopathologic characteristics of congenital bicuspid aortic valves necessitating surgical intervention. METHODS: Among 374 aortic valve procedures during the past 15 years, 63 cases of bicuspid aortic valve were encountered. Patients included 45 males and 18 females; mean age was 53 years (range: 14 to 76 years). RESULTS: Thirty-two patients demonstrated aortic stenosis (AS), 27 aortic regurgitation (AR), and four had both conditions. Patients with AR were significantly younger than those with AS (45 +/- 13 versus 60 +/- 11 years; p < 0.01). Histologic study of the excised valve disclosed severe myxoid degeneration in 16 of 27 patients with AR. These patients underwent surgery at a younger age than the other 11 with calcification and endocarditis (40 +/- 13 versus 52 +/- 10 years; p = 0.01). Based on the macroscopic appearance, the lesions were divided into those with (n = 38) and without (n = 25) raphe. Twenty-one patients (55%) in the former group demonstrated AR, whereas 19 (76%) in the latter group demonstrated AS. Patients with raphe were significantly younger at the time of surgery than those without raphe (50 +/- 15 versus 57 +/- 11 years; p = 0.02). As a complication, ascending aortic aneurysm was observed in six patients. CONCLUSIONS: In a bicuspid aortic valve, calcification with stenosis commonly occurs in most older patients. However, in some young adult patients with raphe, AR may result from myxoid degeneration. The presence of raphe in the bicuspid valve appears to have a significant influence on valve hemodynamics.

Adolescent↗

PubMed1997

Bone mass loss due to estrogen deficiency is compensated in transgenic mice overexpressing human osteoblast stimulating factor-1.

Osteoblast stimulating factor-1 (OSF-1) stimulates in vitro proliferation and differentiation of osteoblastic cells, and its gene is expressed in the bone and brain tissues in mammals and amphibians. To evaluate the in vivo function of OSF-1 in bone metabolism, transgenic mice overexpressing the human osf-1 gene driven by the osteocalcin promoter were generated. Femoral bone mineral content was increased in transgenic mice relative to wild-type controls as estimated by ash assay, depending on the transgene copy number per cell. In ovariectomized mice, bone mass loss due to estrogen deficiency was observed in both transgenic and control mice but bone mass was still higher in transgenic mice than in controls. Bone mass in ovariectomized transgenic mice was comparable to that in wild-type mice without ovariectomy. These observations indicate that OSF-1 may direct in vivo appositional bone formation by increasing osteoblast activity rather than decreasing osteoclast activity, suggesting a new way to treat osteoporosis with OSF-1.

Animals↗

PubMed1997

Role of phospholipids in the protein stability of an insect lipoprotein, lipophorin from Rhodnius prolixus.

Lipophorin (Lp) is the major lipoprotein in insect hemolymph. The structural organization proposed for Lp is basically the same as that suggested for vertebrate lipoproteins, consisting of a hydrophobic core containing neutral lipids, stabilized in the aqueous environment by surrounding polar moieties of protein and phospholipids at the particle surface. After complete removal of phospholipids from Lp by phospholipase A2, the particle remains soluble [Gondim, K. C., Atella, G. C., Kawooya, J. K., & Masuda, H. (1992) Arch. Insect Biochem. Physiol. 20, 303-314]. However, studies on the roles of phospholipid on the structural stability of Lp are still lacking. In the present work, we have studied the structure and stability of dephospholipidated lipophorin (d-Lp). Trypsinolysis of d-Lp indicated no exposure of new cleavage sites on the protein when compared to Lp. However, an enhanced rate of proteolysis of the apoproteins (especially apolipophorin II) was observed in d-Lp. Circular dichroism analysis indicated that the secondary structure of Lp was not significantly affected by phospholipid removal. Furthermore, the exposure of tryptophan residues to the aqueous solvent in d-Lp was the same as in Lp, as indicated by intrinsic fluorescence emission spectra and fluorescence quenching experiments. Interestingly, d-Lp was more resistant to denaturation by guanidine hydrochloride than Lp. d-Lp was also found to be less sensitive than Lp to structural changes induced by hydrostatic pressure. Taken together, these results indicate that, although changes in its structural organization were subtle, dephospholipidated lipophorin may have additional protein-protein and/or protein-neutral lipid interactions that are responsible for the observed increase in stability. Therefore, phospholipids are not only not essential for Lp stability, but their presence in the particle seems to result in a less stable structure in the aqueous environment.

Animals↗

PubMed1997

Swine influenza virus strains recognize sialylsugar chains containing the molecular species of sialic acid predominantly present in the swine tracheal epithelium.

We determined the ratio of N-glycolylneuraminic acid (Neu5Gc) to N-acetylneuraminic acid (Neu5Ac) in swine respiratory epithelia by fluorometric high-performance liquid chromatography, and examined the binding specificity of swine influenza virus strains for gangliosides containing different molecular species of sialic acid (Neu5Ac and Neu5Gc), and for bovine erythrocyte sialoglycoprotein 2 (GP-2) containing Neu5Gc as its predominate sialic acid (96% of total sialic acids). The presence of Neu5Gc, which had not been detected in human tracheal epithelia, and Neu5Ac in swine tracheal epithelia was observed in a 1:1 ratio. The swine influenza virus H1 and H3 isolates tested, except for A/swine/Iowa/15/30 (H1N1), displayed a marked binding ability for sialylsugar chains containing Neu5Gc compared with that of the human influenza virus strains. These results suggest that swine influenza viruses recognize sialylsugar chains containing the molecular species of sialic acid present predominantly in the swine tracheal epithelium.

Animals↗

PubMed1997

Molecular cloning and sequence analysis of the cDNA for the mouse counterpart to adult hamster liver purified growth inhibitory factor.

A cDNA clone encoding the mouse counterpart to adult hamster liver purified growth inhibitory factor (PGIF) was isolated from a mouse liver cDNA library by using antibodies raised against PGIF and sequenced. It contained a single open reading frame with a coding capacity for a 323 amino acid protein. Sequence analysis showed that it shared high homology with rat- and human liver arginases: the cDNA clone was 92% identical for rat arginase at the nucleotide level and was 93% identical to it at the deduced amino acid level. These results suggest that PGIF derived from adult hamster liver was identical or closely related to an isoform of hamster liver arginases.

Amino Acid Sequence↗

PubMed1997

Lipophorin density variation during oogenesis on Rhodnius prolixus.

The density of lipophorin was determined in adult females of Rhodnius prolixus on different days after a meal. Several populations od lipoproteins, differing in density but always in the range of HDL, were found in the hemolymph. The density of the major population was analyzed and a complex profile of density variation was found associated with the principal metabolic events in these insects digestion and oogenesis. During the initial three days after the blood meal, with the onset of the digestive process, the density of lipophorin decreased from 1.1185 g/l to 1.1095 g/l, associated with the transfer of lipids from midgut to the lipophorin particles. During the period of intense vitellogenesis and lipid uptake by the ovary, the lipophorin density started to increase and reached the value, 1.1322 g/l, and remained stable up to the end of oogenesis. As soon as the requirement of lipids to build up the oocytes ceased, the density of lipophorin decreased to its initial value associated with the transfer of lipids from fat body to lipophorin. Soon after the blood meal the midgut was the main source of lipids capable of replenishing the lipophorin particles, while the fat body assumed this function during the succeeding days and reached its maximum capacity around day 10, as estimated by the rate of lipid transfer. The principal lipids transferred were phospholipids and diacylglycerols. Except in the protein/lipid ratio no major changes were observed among different lipids isolated from lipophorin of different densities.

Animals↗

PubMed1997

A possible role of endogenous inhibitor for nitric oxide synthesis in the bovine ciliary muscle.

The present experiments were designed to investigate the possible role of endogenous methylarginine derivatives such as NG-monomethyl-L-arginine, asymmetrical NG,NG-dimethyl-L-arginine and symmetrical NG,N'G-dimethyl-L-arginine for the nitric oxide synthesis in the bovine ciliary muscle. The contents of asymmetrical NG,NG-dimethyl-L-arginine and symmetrical NG,N'G-dimethyl-L-arginine in the bovine ciliary muscle were determined to be 370.2 +/- 27.6 (n = 5) and 182.4 +/- 22.9 (n = 5) pmoles g-1 wet weight, respectively by means of the automated high-performance liquid chromatography. NG-Monomethyl-L-arginine was below the assay limits. On the basis of the total tissue water content (0.792 +/- 0.006 ml g-1 wet weight, n = 14), the concentrations of asymmetrical NG,NG-dimethyl-L-arginine and symmetrical NG,N'G-dimethyl-L-arginine were tentatively estimated to be (4.7 +/- 0.3) x 10(-7) M (n = 5) and (2.3 +/- 0.3) x 10(-7) M (n = 5), respectively. A23187 (10(-7)-3 x 10(-4) M) produced a concentration-dependent relaxation of the ciliary muscle strips which had been contracted with 10(-5) M carbachol. Authentic asymmetrical NG,NG-dimethyl-L-arginine (3 x 10(-6)-3 x 10(-4) M), but not symmetrical NG,N'G-dimethyl-L-arginine (3 x 10(-4) M), inhibited the 10(-6) M A23187-induced relaxation in a concentration-dependent manner. The inhibition with asymmetrical NG,NG-dimethyl-L-arginine (10(-4) M) was reversed by an addition of 3 x 10(-3) M L-arginine, but not by 3 x 10(-3) M D-arginine. The A23187 (10(-6) M)-induced relaxation was enhanced by 3 x 10(-3) M L-arginine or superoxide dismutase (50 U ml-1), whereas it was inhibited by carboxy-PTIO (3 x 10(-4) M), a scavenger of nitric oxide, or methylene blue (10(-5) M), an inhibitor of guanylate cyclase. The carbachol-induced contraction was enhanced by asymmetrical, NG,NG-dimethyl-L-arginine (10(-5) M) and inhibited by 3 x 10(-3) M L-arginine. Any effect of prostanoid formation during the A23187-induced relaxation was ruled out by using indomethacin (10(-5) M). Sodium nitroprusside (10(-5) M), a donor of nitric oxide, also produced a relaxation, which was inhibited by methylene blue (10(-5) M) or carboxy-PTIO (3 x 10(-4) M) and was augmented by superoxide dismutase (50 U ml-1), but unaffected by asymmetrical NG,NG-dimethyl-L-arginine (3 x 10(-4) M) or L-arginine (3 x 10(-3) M). These results lead us to speculate that the nitric oxide synthesized endogenously from L-arginine may play a role for mediating relaxation of the bovine ciliary muscle and that the endogenous asymmetrical NG,NG-dimethyl-L-arginine may be involved in inhibiting the biosynthesis of nitric oxide when there are increased intracellular concentrations of the methylarginine under certain circumstances.

Animals↗

PubMed1997

A localized fibrous tumor (mesothelioma) in the mediastinum: report of a case.

We report herein the rare case of a 51-year-old Japanese woman who underwent thoracotomy for a mass in the mediastinum which was found to be a benign localized fibrous tumor, otherwise known as a mesothelioma. The clinical behavior of this tumor is thought to be unpredictable, and therefore we emphasize that long-term follow-up of patients with localized fibrous tumors is necessary, even if the histological features are benign.

Female↗

PubMed1997

Cerebellar myeloblastoma formation in CD7-positive, neural cell adhesion molecule (CD56)-positive acute myelogenous leukemia (M1).

We present a first report of a CD7+ acute myelogenous leukemia patient who developed intracranial myeloblastomas. The patient was neurologically normal on physical examination at presentation. The peripheral leukocyte count was extremely high (203.6 x 10(9)/l). The blasts expressed CD7 and CD56 (neural cell adhesion molecule) in addition to CD13, CD33, CD34, and HLA-DR. The karyotype of bone marrow cells was normal. The patient was diagnosed as having acute myelogenous leukemia (AML, M1). Following a short period of complete remission, bone marrow relapse and meningeal leukemia occurred, and the patient died of respiratory failure. Autopsy revealed that blasts had invaded the subarachnoid space and cerebellum, and two myeloblastomas were found in the cerebellar hemisphere. Both CD7+ and CD56+ AML have been reported to have a high incidence of central nervous system involvement. CD7+ CD56+ AML calls for prophylaxis of central nervous system leukemia.

Antigens, CD7↗

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

The presence of h2-calponin in human keratinocyte.

Calponin (h1 isoform) was characterized as a smooth muscle specific, actin-, tropomyosin-, calmodulin-binding protein and described as a factor which inhibits contraction. H2-calponin, encoded by a different gene from h1-calponin, was identified from the smooth muscles of mouse and pig. However, non-muscle calponin analogues have recently been reported in rat and pig brains. Here we show the presence of calponin expressed in human skin tissue and in cultured human keratinocytes using polyclonal antibodies to bovine aortic smooth muscle calponin. Western blot analysis demonstrated that calponin with a molecular weight around 36,000 existed in extracts of keratinocytes. Immunofluorescence microscopy displayed the localization of calponin in the cytoplasm of the basal cells in situ, and along the cell-to-cell borders in cultured human keratinocytes maintained in standard calcium medium. Furthermore, according to RT-PCR analysis using human h1- and h2-calponin-specific primers, calponin expressed by cultured human keratinocytes was identified as the h2 isoform. We demonstrated the presence of h2-calponin in human keratinocytes, and it might play a role in the structural organization of actin cytoskeleton at the cytoplasmic region of cell-to-cell junctions of keratinocytes.

Actins↗

PubMed1997

Transition zone ratio and prostate-specific antigen density as predictors of the response of benign prostatic hypertrophy to alpha blocker and anti-androgen therapy.

OBJECTIVE: To determine whether transrectal ultrasonography (TRUS) can predict the clinical response of patients with benign prostatic hypertrophy (BPH) to alpha 1-blocker and anti-androgen therapy. PATIENTS AND METHODS: From April 1994 to July 1995, 128 patients with BPH were randomized to treatment for 6 months with either tamsulosin (a long-acting selective alpha 1-blocker) or allylestrenol (an anti-androgen), with 64 patients receiving tamsulosin (0.2 mg/day) and 64 receiving allylestrenol (50 mg/day). The results of TRUS, uroflowmetry and the American Urologic Association (AUA) symptom score were compared before and after treatment. TRUS was used to calculate the transition zone (TZ) volume, transition zone ratio (TZ ratio = TZ volume/total prostate volume), total prostate volume and prostate-specific antigen density (PSAD). RESULTS: Both groups showed a statistically significant improvement in the AUA symptom score, quality-of-life (QOL) score and peak urinary flow rate (Qmax) at 6 months (P < 0.001). In the tamsulosin group, there was a significant negative correlation between the pretreatment PSAD and the percentage change in Qmax (r = -0.640, P < 0.001), while there was a positive correlation between PSAD and the percentage change in the AUA symptom score (r = 0.589, P < 0.001). On the other hand, the allylestrenol group showed a significant positive correlation between PSAD and the percentage change in Qmax (r = 0.397, P < 0.01) and a negative correlation between PSAD and the AUA symptom score (r = -0.313, P < 0.01). CONCLUSION: Patients with a high pretreatment PSAD responded well to anti-androgen therapy, while those with a low PSAD responded better to alpha 1-blocker therapy.

Adrenergic alpha-Antagonists↗

PubMed1997

Predictive value of serum immunosuppressive acidic protein for staging renal cell carcinoma: comparison with other tumour markers.

OBJECTIVE: To examine the usefulness of serum immuno-suppressive acidic protein (IAP) as a predictor for staging renal cell carcinoma (RCC), using receiver-operator characteristic (ROC) analysis, and to compare IAP with other tumour markers. PATIENTS AND METHODS: From September 1983 to December 1995, serum IAP was measured in 133 untreated patients with RCC (mean age 60.1 years, SD 11.4. range 31-84). The erythrocyte sedimentation rate (ESR), the levels of fibrinogen, C-reactive protein (CRP), and alpha 2-globulin were also measured. To compare these markers as predictors of local involvement of the renal capsule, lymph node and distant metastasis, the area under the corresponding ROC curve was calculated. Tumour size at the time of resection was added in this analysis for comparison with the levels of these tumour markers. RESULTS: The final pathological stage was T1 or T2 in 101 patients and T3 or T4 in 32, while it was N0 in 122 patients, N1-3 in seven, M0 in 114 patients and M1 in 19. The area of the ROC curve for tumour size was greatest (0.843) for staging of the local extent (T1/T2 versus T3/T4) and that for IAP was 0.714, similar to the values for fibrinogen, ESR and CRP. For predicting lymph node metastasis, IAP and fibrinogen were the most important (0.864). However, IAP alone (0.894) was the most important predictor of distant metastasis. Using an IAP threshold of 600 micrograms/mL gave a high sensitivity and specificity for detecting lymph node and distant metastasis. CONCLUSION: IAP is a valuable predictor of lymph node and distant metastasis in patients with RCC, although it is inferior to tumour size in predicting local involvement of the renal capsule. The appropriate threshold value of IAP for detecting lymph node and distant metastasis is 600 micrograms/mL.

Adult↗

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

Structure and expression of the human SM22alpha gene, assignment of the gene to chromosome 11, and repression of the promoter activity by cytosine DNA methylation.

To investigate the molecular mechanisms that control expression of smooth muscle cell (SMC) differentiation genes, we have isolated the human SM22a gene, which is composed of five exons and four introns, spanning an approximately 6-kilobase (kb) genomic DNA at chromosome region 11q23.2. Expression of the SM22a messenger RNA was detected in serum-stimulated cell cultures including SMC, undifferentiated skeletal muscle-lineage cells, and fibroblasts, and it was down-regulated in SMC of balloon-injured atheromatous human vessels. A major transcription start site of the SM22alpha gene is located at 75 base-pairs (bp) upstream of the ATG start codon. Analysis of the 2.6 kb 5'-upstream sequence demonstrated that two CArG/SRF-boxes and two GC-box/Sp1-binding sites were present at bp -147 and -274, and at bp -233 and -1635, respectively. The nucleotide sequences of the two CArG/SRF-boxes and the proximal GC-box/Sp1 binding site are 100% conserved with those of the murine SM22alpha genes [Solway, J., Seltzer, J., Samaha, F.F., Kim, S., Alger, L.E., Niu, Q., Morriesey, E.E., Ip, H.S., and Parmacek, M.S. (1995) J. Biol. Chem. 270, 13460-13469; Kemp, P.R., Osbourn, J.K., Grainger, D.J., and Metcalf, C. (1995) Biochem. J. 310, 1037-1043]. Cell transfection assays using a luciferase reporter gene construct containing the 455-bp 5'-flanking region (positions -26 to -480) showed that methylation of the CpG dinucleotides within this segment reduces its transcriptional activity. The results imply a novel mechanism for transcriptional control of the SMC differentiation-specific gene promoter.

Amino Acid Sequence↗