Biomedical subjects

S H Yang

Publications and source records attributed to S H Yang.

At least 37 records · Page 2Linked to original sources

PubMed2001

Vascular effects of synthetic or natural progestagen combined with conjugated equine estrogen in healthy postmenopausal women.

BACKGROUND: Synthetic, not natural, progestagen may negate the favorable effects of estrogen. Nonetheless, observational studies report no differences in risk for clinical cardiovascular events between users of unopposed estrogen and users of estrogen combined with synthetic progestin. METHODS AND RESULTS: In a double-blind study, we randomly assigned 20 healthy postmenopausal women to micronized progesterone (MP) 200 mg or medroxyprogesterone acetate (MPA) 10 mg for 10 days with conjugated equine estrogen (CEE) 0.625 mg for 25 days and the remaining 5 days off cyclically during 2 months, followed by crossover to the alternate therapy. CEE+MP and CEE+MPA significantly improved the percent flow-mediated dilator response to hyperemia relative to baseline measurements (P=0.004 by ANOVA) by a similar degree (P=0.863). Both therapies significantly decreased E-selectin, intercellular adhesion molecule (ICAM)-1, and vascular cell adhesion molecule (VCAM)-1 levels from baseline values (P<0.001, P=0.048, and P=0.016 by ANOVA, respectively) by a similar degree (P=0.977 for ICAM-1 and P=0.541 for VCAM-1, respectively). CEE+MPA decreased E-selectin levels more than CEE+MP did (P=0.040). Both therapies significantly decreased monocyte chemoattractant protein-1 levels from baseline values (P<0.005 by ANOVA) by a similar degree (P=0.194). Both therapies significantly decreased tissue factor antigen and increased tissue factor activity levels from baseline values (P=0.003 and P<0.001 by ANOVA, respectively) by a similar degree (P=0.652 for antigen and P=0.173 for activity). Both therapies significantly lowered plasma plasminogen activator inhibitor-1 levels from baseline values (P<0.001 by ANOVA) by a similar degree (P=0.533). CONCLUSIONS: CEE+MP and CEE+MPA provide similar improvement in endothelium-dependent vasodilator responsiveness and effects on markers of inflammation, hemostasis, and fibrinolysis inhibition in healthy postmenopausal women.

Chemokine CCL2↗

PubMed2001

Effect on human attention of exposure to the electromagnetic field emitted by mobile phones.

This study examined the effect of exposure to the electromagnetic field emitted by mobile phones on human attention. Three measures of attention were administered to 72 teenagers, 37 of whom were mobile phone users. The results showed that the mobile phone users performed better on one of the three measures of attention than did the non-mobile phone users. The results suggest that exposure to the electromagnetic field emitted by mobile phones may have a mild facilitating effect on attention functions, which is consistent with previous observations that exposure to the electromagnetic field has a facilitating effect on cognitive processing. The possibility that mobile phone users may be naturally better at multiple tasking tasks was discussed.

Adolescent↗

PubMed2001

Selective targeting of MAPKs to the ETS domain transcription factor SAP-1.

MAPK pathways play important roles in regulating the key cellular processes of proliferation, differentiation, and apoptosis. There are multiple MAPK pathways, which are subject to different regulatory cues. It is important that these pathways maintain specificity in signaling to elicit the activation of a specific program of gene expression. MAPK-docking domains in several transcription factors have been shown to play important roles in determining the specificity and efficiency of their phosphorylation by MAPKs. Here we investigate the mechanisms by which MAPKs are targeted to the ETS domain transcription factor SAP-1. We demonstrate that SAP-1 contains two different domains that are required for its efficient phosphorylation in vitro and activation in vivo by ERK2 and a subset of p38 MAPKs. The D-domain is closely related to other MAPK-docking domains, but exhibits a novel specificity and serves to promote selective targeting of ERK2, p38alpha, and p38beta(2) to SAP-1. A second important region, the FXF motif, also plays an important role in directing MAPKs to phosphorylate SAP-1. The FXF motif promotes targeting by ERK2 and, to a lesser extent, p38alpha, but not p38beta(2). Our data therefore demonstrate that a modular system of motifs is responsible for directing specific MAPK subtypes to SAP-1, but also point to important distinctions in the mechanism of action of the D-domain and FXF motif.

Amino Acid Sequence↗

PubMed2001

Hepatitis C virus core protein inhibits interleukin 12 and nitric oxide production from activated macrophages.

A characteristic feature of hepatitis C virus (HCV) infection is a high frequency of persistence and the progression to chronic liver diseases. Recent data suggest that prevalent T helper (Th) 2 immunity as well as weak HCV-specific T-cell response is associated with viral persistence. Here, we showed that the production of interleukin 12 (IL-12) and nitric oxide (NO) that is critical for the induction of Th1 and innate immunity, but not that of tumor necrosis factor alpha (TNF-alpha), was significantly suppressed in both HCV core-expressing macrophage cell lines and mouse peritoneal macrophages treated with recombinant core protein. In addition, IL-12 p40 promoter activity was repressed by the presence of HCV core in macrophages stimulated with lipopolysaccharride (LPS) following IFN-gamma treatment, indicating that IL-12 production may be downregulated at the transcriptional level. We also found that proliferation of T cells and IFN-gamma production in mixed lymphocyte reactions (MLR) with core-expressing cells were inhibited. Taken together, our results suggest that HCV core protein could play roles in suppressing the induction of Th1 immunity through inhibition of IL-12 and NO production.

Animals↗

PubMed2001

Carcinoembryonic antigen in monitoring of response to systemic chemotherapy in patients with metastatic colorectal cancer.

The response to chemotherapy of solid tumors is generally assessed by measuring tumors visualized by imaging. However, the response assessment based on imaging is not always feasible because patients often have disease not measurable by imaging, such as diffuse peritoneal dissemination. We evaluated the correlation between the change on imaging and change in CEA levels for assessing chemotherapeutic response of patients with metastatic colorectal cancer. Between July 1993 and August 1999 we retrospectively examined 136 patients with metastatic colorectal carcinoma, all of whom had measurable lesions. Forty patients received oral tegafur-uracil (300 mg/m2/day) plus folinic acid (60 mg/day) for 4 weeks, repeated every 5 weeks, as the firstline treatment. Another 96 patients received either a weekly intravenous bolus injection of 5-fluorouracil (400 mg/m2) plus folinic acid (20 mg/m2), or an intravenous bolus injection of 5-fluorouracil (425 mg/m2) plus folinic acid (20 mg/m2) for 5 consecutive days every month. Responders, based on CEA assessment, were defined as those with a greater than 50% drop in CEA level for more than 4 weeks. The pretreatment CEA levels were elevated beyond the normal cutoff value in 110 (81%) patients. A response rate of 18.4% (95% CI, 11.9-24.9%), including 8 complete remissions and 17 partial remissions, was achieved according to imaging studies. The response rate assessed by CEA was 25% (34/136). Sixteen responders (47%) based on CEA had no remission on imaging. The sensitivity of change in CEA levels in the prediction of true responders and progressive diseases on imaging were 72% and 81%, respectively. In terms of the positive predictive value, change in CEA levels in the prediction of true responders and progressive disease on imaging were 53% and 85%, respectively. Patients with remarkable falls on CEA levels survived significantly longer than nonresponders (P < 0.001, log-rank test). At follow-up of 48 months the median survival for responders and nonresponders assessed by CEA was 28 months and 13 months, respectively. These data suggest that measurement of CEA levels might be helpful in monitoring chemotherapeutic response when imaging study is unsuitable for assessing the response in clinical practice. Furthermore, measurement of CEA levels may be helpful in determining the prognosis of patients with metastatic colorectal cancer receiving chemotherapy.

Adult↗

PubMed2001

Effect of ventilation mode on gas exchange during partial liquid ventilation at different perfluorocarbon doses in surfactant-depleted lung.

Although gas ventilation is an integral part of partial liquid ventilation (PLV), the role of ventilation mode during PLV is not established, especially at a varying perfluorocarbon dose. In 10 surfactant-depleted rabbits, PLV was performed at a low dose (10 ml/kg) and at a functional residual capacity (FRC) dose (30 ml/kg) of perfluorodecalin in pressure-control (PC) and volume-control (VC) modes in balanced sequence. In these four PLV trials, PC mode was adjusted to be identical to VC mode with regard to tidal volume and inspiratory-to-expiratory ratio. PaO2 during PLV in PC mode was higher than in VC mode at the Low dose (159 plus minus 93 mm Hg, 115 plus minus 75 mm Hg, respectively: p = 0.005) and at the FRC dose (228 +/- 114 mm Hg, 164 +/- 104 mm Hg, respectively: p = 0.002). PaCO2 during PLV in PC mode was lower than in VC mode at the Low dose (59 +/- 18 mm Hg, 72 +/- 20 mm Hg, respectively: p = 0.005), whereas PaCO2 at the FRC dose was not different between modes. Curves of inspiratory flow appeared least deformed with PLV in PC mode at the Low dose, whereas they were saw-tooth deformed with PLV in VC mode at both doses. Actual time for inspiratory gas flow during PLV was shorter in PC mode compared with VC mode at both doses. In conclusion, in surfactant-depleted rabbit, gas exchange during PLV was better with PC mode compared with VC mode, especially at a low perfluorocarbon dose. Given the same tidal volume, PC appeared to insufflate the perfluorocarbon-filled lung better than VC at both low and FRC doses of perfluorocarbon.

Animals↗

PubMed2001

Gasless laparoscopy-assisted colorectal surgery.

BACKGROUND: Laparoscopy has gained wide acceptance as a treatment modality in a variety of colonic and rectal disorders. Currently, most laparoscopic procedures are performed using a carbon dioxide (CO2) pneumoperitoneum, which can lead to cardiopulmonary loading and subsequent complications. The object of this study was to assess the feasibility of gasless laparoscopy-assisted colorectal surgery (GLACS) as an alternative method. METHODS: Patients with benign colonic lesions were enrolled in the study. The operative field was exposed with a subcutaneous wire lifting system. A small incision, ~5 cm in length, was made early in the operation. The surgeon operated through the trocar ports and this incision using both laparoscopic and conventional instruments. The cardiopulmonary responses of the patients were monitored continuously during the operation. RESULTS: Fifteen consecutive patients underwent GLACS. In two patients (13.3%), conversion to open surgery was necessary. The exposure and ease of the procedure were acceptable. However, when the patients were stratified into hemicolectomy and sigmoidectomy groups, GLACS scored more favorably in the sigmoidectomy group. There were no operative deaths. One minor complication developed postoperatively. All of the patients recovered uneventfully, with return of bowel function in 2.8 +/- 0.1 days. The mean postoperative hospital stay was 6.4 +/- 0.4 days. The cardiac and pulmonary status of the patients remained stable during the operation. CONCLUSION: Gasless laparoscopy-assisted colorectal surgery is technically feasible; thus, it provides an alternative means for the performance of minimal-access surgery.

Aged↗

PubMed2001

Cytotoxicity and arecoline mechanisms in human gingival fibroblasts in vitro.

Betel nut chewing, like cigarette smoking, is a popular oral habit which impinges on the daily lives of a population of approximately 200 million. People who chew betel nuts have a higher prevalence of periodontal diseases than those who do not. Many of the undesirable effects of betel nuts have been attributed to arecoline, a major component of the particular alkaloid in betel nuts. In this in vitro study, we have focused on the effects of arecoline and the role it could play in periodontal breakdown via its direct effects on human gingival fibroblasts. Human gingival fibroblasts were derived from three healthy individuals undergoing crown-lengthening procedures. We found that arecoline is cytotoxic to human gingival fibroblasts at a concentration higher than 50 micrograms/ml by depleting intracellular thiols and inhibiting mitochondrial activity (P < 0.05). In addition, the cells displayed a marked arrest at G2/M phase in a dose-dependent manner. Repeated and long-term exposure to arecoline could impair the gingival fibroblast functions. As they are cytotoxic, the use of betel nut products in conjunction with periodontal therapy may interfere with optimal healing and/or lead to further periodontal breakdown.

Adult↗

PubMed2001

Stress analysis of the distal locking screws for femoral interlocking nailing.

In femoral locked nailing, the distal locking screws are vulnerable to mechanical failure. Biomechanical studies have shown that the stress on these screws is substantially affected by the fit of the nail in the medullary canal. In this study, a "closed form" mathematical model based on elastic beam-column theory was developed to investigate how the nail-cortical contact, which was simulated by a linear elastic foundation, affected the stress on the distal locking screws. Providing data for the model was a construct of a fractured femur with an intramedullary locked nail loaded by an eccentric vertical load. The stress on the locking screw was analyzed as a function of the distance from the fracture to the locking screw in the distal fragment under two situations: with and without nail-cortical contact in the distal fragment. With nail-cortical contact, the screw stress decreased as the length of nail-cortical contact and the distance between the distal locking screw and the fracture site increased, but this stress contrarily increased when the nail reached the femoral region at which the screw length increased. The screw stress was much higher without nail-cortical contact than with contact and continued to increase as the nail was inserted further. The mathematical model developed here can be a convenient means of rapid stress evaluation and parametric analysis for locked femoral nailing. It may be used to improve the design of interlocking nails and surgical technique.

Biomechanical Phenomena↗

PubMed2001

Sodium nitroprusside induces apoptosis of H9C2 cardiac muscle cells in a c-Jun N-terminal kinase-dependent manner.

Sodium nitroprusside (SNP) induces apoptosis in H9C2 cardiac muscle cells. Treatment with an exogenous NO donor SNP (2 mM) to H9C2 cells resulted in apoptotic morphological changes; a bright blue-fluorescent condensed nuclei and chromatin fragmentation by fluorescence microscope of Hoechst 33258-staining. The activity of caspase-3 like protease was increased during SNP-induced cell death. However, the activity of caspase-1 like protease was not affected by SNP. Pretreatment with Z-VAD-FMK (a pan-caspase inhibitor) or Ac-DEVD-CHO (a specific caspase-3 inhibitor) abrogated the SNP-induced cell death. SNP markedly activated three MAP kinases (JNK/SAPK, ERK and p38 MAP kinase) in the cardiac muscle cells. In this study, selective inhibition of the ERK or p38 MAPK pathway (by PD98059 or SB203580, respectively) had no effect on the extent of SNP-induced apoptosis in cardiac muscle cells. In contrast, inhibition of the JNK pathway by transfection of a dominant negative mutant of JNK markedly reduced the extent of SNP-induced cell death. Taken together, we suggest that JNK/SAPK will be related to SNP-induced apoptosis of H9C2 cardiac muscle cells.

Amino Acid Chloromethyl Ketones↗

PubMed2001

Decreased serum IgE level, decreased IFN-gamma and IL-5 but increased IL-10 production, and suppressed cyclooxygenase 2 mRNA expression in patients with perennial allergic rhinitis after treatment with a new mixed formula of Chinese herbs.

A new mixed formula of Chinese herbs containing Shin-yi-san + Xiao-qing-long-tang + Xiang-sha-liu-jun-zi-tang by the weight of 9 + 3 + 3 g/day was prescribed for the treatment of patients with perennial allergic rhinitis for 3 months (the composition of each herb is shown in the tables of the article). We classified the patients into high (H-IgE) and low IgE (L-IgE) groups according to the titer of serum total IgE (> 200 KIU/l in H-IgE vs. < 200 KIU/l in L-IgE) and the presence of house dust mite-specific IgE. The nasal symptomatic score in the high IgE group was significantly improved from 7.19 +/- 0.18 before treatment to 2.67 +/- 0.37 after treatment. In addition, the serum total and house dust mite-specific IgE level were also decreased after treatment. For elucidating the working mechanism of the mixed formula, the Th1 (IFN-gamma) and Th2 (IL-4, IL-5, IL-10 and IL-13) cytokine production by phytohemagglutinin (PHA)-stimulated mononuclear cells (2 x 10(6) cells/ml) and cyclooxygenase type 2 (COX-2) mRNA expression in LPS or IL-13-stimulated PMN were compared before and after 3 months of treatment. We found that the mixed formula treatment significantly enhanced IL-10 but decreased IFN-gamma and IL-5 production by PHA-stimulated mononuclear cells. The IL-5 production was also decreased by PHA-stimulated lymphocyte. In addition, the COX-2 mRNA expression in stimulated PMN was significantly suppressed after treatment. These results suggest that the new mixed formula treatment is beneficial to the patients with perennial allergic rhinitis via modulating the function of lymphocytes and neutrophils.

Adult↗

PubMed2001

Hepatitis C virus core protein promotes cell proliferation through the upregulation of cyclin E expression levels.

AIMS/BACKGROUND: The hepatitis C virus (HCV) core protein is known to play an important role in hepatocarcinogenesis. Recent studies have suggested that the increased proliferation rate of hepatocytes is a major risk factor for the development of hepatocellular carcinoma. In this study, we investigated whether the HCV core protein promotes the cell growth rate through the modulation of cyclin E expression levels. METHODS/RESULTS: HCV core stable transfectant Rat-1 cell lines showed a markedly increased proliferation rate compared to mock cells. Cyclin E expression and its associated kinase activities were remarkably increased in HCV core stable transfectants. Cyclin E mRNA levels were also upregulated in these cell lines. CONCLUSIONS: Our data suggest that the HCV core protein promotes cell proliferation through upregulation of the cyclin E expression levels, implying this property of HCV core protein plays an important role in hepatocarcinogenesis.

Animals↗

PubMed2001

Comparison of blood counts in venous, fingertip and arterial blood and their measurement variation.

We compared routine blood pictures in venous, fingertip and arterial blood and their measurement variation. A pair of venous and fingertip blood samples were simultaneously collected from 24 volunteers, and another pair of venous and arterial samples from another 12 volunteers. The volunteers were healthy adults, aged 20-22 years, with males and females in equal numbers. Three aliquots of blood were taken from each person for three measurements of blood counts, including haemoglobin concentration and haematocrit, using an automatic haematology analyser. Compared to arterial blood, there was a significant increase of erythrocyte count (2.7%) and haematocrit (3.1%) in the venous blood. The total and large leucocyte counts were significantly higher (9.2% and 12.6%, respectively) in the fingertip blood than in the venous blood. There were a decreasing number of leucocytes in the fingertip blood with repeated sampling. The intermeasurement variation for total leucocyte or haemoglobin measurement was significantly larger as measured with the fingertip blood or arterial blood than with the venous blood. The intermeasurement coefficients of variation of haemoglobin (1.3%) and small leucocyte ratio or platelet (approximately 4.0%) measurements with venous and arterial blood were the smallest and largest, respectively. Volume of arterial plasma was diminished by 2-3% after microcirculation. Elevation of total leucocyte count in the fingertip blood was mainly due to the increase of granulocytes. Measurement with venous blood was of better precision than with fingertip or arterial blood.

Adult↗

PubMed2001

Staged reimplantation of total knee arthroplasty after Candida infection.

Prosthetic joint infection with Candida is uncommon. Only 28 cases have been reported in the English literature. Successful reimplantation after eradication of Candida infection has been reported in 3 hip joints and only 1 knee. We present the case of a 68-year-old woman with chronic Candida parapsilosis infection of a prosthetic knee joint. Removal of the prosthesis, thorough débridement, and antifungal therapy treated the infection successfully. Antifungal therapy included 6 weeks of parenteral administration of fluconazole followed by 4 weeks of oral fluconazole. The involved knee joint was reimplanted 3 months after initial treatment. The prosthetic joint was pain free and functioned satisfactorily during the ensuing 4 years. No recurrence of infection was noted. The principle in treating Candida prosthetic infection generally has been the same as that of bacterial prosthetic infection. In chronic cases, removal of implants, thorough débridement, and effective antifungal therapy are mandatory for the eradication of infection. Reimplantation of the prosthesis can be performed successfully in a staged surgical procedure with the interval between the 2 stages shortened to 3 months.

Aged↗

PubMed2001

Adenomatous polyposis coli gene mutation and decreased wild-type p53 protein expression in oral submucous fibrosis: a preliminary investigation.

OBJECTIVE: The purpose of this study was to identify the adenomatous polyposis coli (APC) tumor suppressor gene mutation and level of wild-type p53 protein expression in patients with oral submucous fibrosis (OSF). STUDY DESIGN: Cells from OSF and control subjects were cultured in Dulbecco modified Eagle medium with 10% fetal bovine serum at 37 degrees C. Genomic DNA was extracted from cultured cells and used as a template for polymerase chain reaction amplification of the APC tumor suppressor gene. The presence of wild-type p53 protein in cell lysates of cultured cells was analyzed by Western blot. Data were analyzed by the sign test for nonparametric samples and by analysis of variance. RESULTS: The results showed that the APC gene of explant cultured cells from OSF patients (8/8) had a CGA-to-GGA transition mutation at codon 498 that resulted in an Arg-to-Gly missense mutation (P <.01). All (8/8) normal HGF cultures revealed expression of the wild-type APC protein. Cells cultured from 7 of 8 OSF patients were also found to have a single nucleotide deletion at nucleotide 1494 that resulted in creating a stop codon (TGA) at codon 504 (P <.01). This created a premature signal for the endpoint of translation and thus resulted in the generation of a truncated protein product that encodes a polypeptide of 503 amino acid residue. It was found that wild- type p53 protein in human gingival fibroblast cell cultures was significantly higher than in OSF cells (P <.01). CONCLUSION: Alterations of the APC and wild-type p53 tumor suppressor genes in OSF may imply a risk for progression to oral cancer.

Adenomatous Polyposis Coli↗

PubMed2001

A Korean family with a dominantly inherited beta-thalassemia due to Hb Durham-N.C./Brescia.

We describe the molecular and the hematological characteristics of a Korean family with a dominantly inherited beta-thalassemia. Carriers were characterized by moderate anemia, hypochromia, microcytosis, elevated Hb A2 and Hb F levels, and splenomegaly. DNA analysis revealed a CTG (Leu) to CCG (Pro) substitution at codon 114 of the beta-globin gene, that leads to a highly unstable hemoglobin variant, Hb Durham-N.C./Brescia, and this was linked to the beta haplotype V, [+----+-], and framework 2. RNA analysis showed that the proband had comparable levels of mutant and normal beta-mRNA. Translation of the mutant mRNA would give rise to non-functional hyperunstable beta-globin chains, and their degradation would, by placing an additional burden on the proteolytic process of the red blood cell precursors, result in a more severe phenotype.

Adolescent↗

PubMed2001

17-beta estradiol can reduce secondary ischemic damage and mortality of subarachnoid hemorrhage.

Subarachnoid hemorrhage (SAH) is a unique disorder commonly occurring when an aneurysm ruptures, leading to bleeding and clot formation, with a higher incidence in females. To evaluate the influence of 17-beta estradiol (E2) in the outcome of subarachnoid hemorrhage, SAH was induced by endovascular puncture of the intracranial segment of internal carotid artery in 15 intact females (INT), 19 ovariectomized females (OVX), and 13 ovariectomized female rats with E2 replacement (OVX + E2). Cerebral blood flow was recorded before and after SAH. All animals were decapitated immediately after death or 24 hours after SAH for clot area analysis. Brains were sliced and stained with 2,3,5-triphenyltetrazolium chloride (TTC) for secondary ischemic lesion analysis. The cortical cerebral blood flow (CBF), which was measured by a laser-Doppler flowmeter, decreased to 29.6%+/-17.7%, 22.8%+/-8.3%, and 43.5%+/-22.9% on the ipsilateral side (P = 0.01), and decreased to 63.4%+/-14.1%, 57.4%+/-11.0%, and 66.6%+/-17.9% on the contralateral side (P = 0.26) in INT, OVX, and OVX + E2, respectively. The subcortical CBF, which were measured by the H2 clearance method, were 7.77+/-12.03, 7.80+/-8.65, and 20.58+/-8.96 mL 100 g(-1) min(-1) on the ipsilateral side (P < 0.01), and 21.53+/-2.94, 25.13+/-3.01, and 25.30+/-3.23 mL 100 g(-1) min(-1) on the contralateral side in INT, OVX, and OVX + E2, respectively. The mortality was 53.3%, 68.4%, and 15.4% in INT, OVX, and OVX + E2, respectively (P = 0.01), whereas no significant difference in clot area was noted among the groups. The secondary ischemic lesion volume was 9.3%+/-8.4%, 24.3%+/-16.3%. and 7.0%+/-6.4% in INT, OVX, and OVX + E2, respectively (P < 0.01). This study demonstrated that E2 can reduce the mortality and secondary ischemic damage in a SAH model without affecting the clot volume.

Animals↗

PubMed2001

Specific association of transcripts of tbzF and tbz17, tobacco genes encoding basic region leucine zipper-type transcriptional activators, with guard cells of senescing leaves and/or flowers.

Induction by low temperature is a common feature of the lip19 subfamily members of the basic region leucine zipper gene family in plants. Here, we characterize two tobacco (Nicotiana tabacum) genes, tbzF and tbz17, belonging to the lip19 subfamily, whose gene products, TBZF and TBZ17, show 73% identity and are located in nuclei. They preferentially bind to DNA fragments spanning A-box/G-box and C-box/G-box hybrid motifs and show transactivation activity in cobombarded tobacco BY-2 cells, indicating they function as transcriptional activators. Transcripts of tbzF were detected at a high level in senescing leaves and flowers. In contrast, tbz17 transcripts could be shown to accumulate in aged leaves but not in flowers. In situ hybridization analysis revealed transcripts of tbzF and tbz17 to be predominantly located in guard cells and vascular tissues of senescing leaves. These results suggest that TBZF and TBZ17 are both involved in controlling gene transcription related to functions of guard cells in senescing leaves and that TBZF bifunctionally acts in floral development.

Amino Acid Sequence↗