Biomedical subjects

Tao Yang

Publications and source records attributed to Tao Yang.

105 records · Page 6Linked to original sources

PubMed2002

Defective human Ether-à-go-go-related gene trafficking linked to an endoplasmic reticulum retention signal in the C terminus.

Mutations in the human Ether-à-go-go-Related gene (HERG), encoding the protein underlying the cardiac K(+) current, I(Kr), cause chromosome 7-linked long QT syndrome (LQT2). In this study, we show that deletion of the C-terminal 147 amino acids (HERG(Delta147)) abolished I(Kr), whereas a larger, 159-amino acid deletion (HERG(Delta159)) identified in an LQT2 kindred did generate I(Kr), albeit with reduced amplitude compared with the wild type. The 12 amino acids present in HERG(Delta147) and absent in HERG(Delta159) include a potential endoplasmic reticulum (ER) retention signal, RGR, which when mutated to LGL (HERG(Delta147-LGL)) restored I(Kr). Streptavidin selection of biotin-labeled surface proteins showed good expression of wild-type and HERG(Delta159) at the cell surface and low expression of HERG(Delta147-LGL) and HERG(Delta147). Additionally, a 100-amino acid peptide spanning the RGR triplet can rescue the defect in HERG(Delta147) when co-expressed as an ER-targeted minigene. Failure of HERG trafficking is known to cause LQT2, and this identified a molecular mechanism underlying this defect. Further, our data indicate that a key function of the C-terminal 104 amino acids is to mask the RGR ER retention signal, which becomes exposed when mutations truncate the HERG C terminus.

Amino Acid Motifs↗

PubMed2002

Allelic variants in long-QT disease genes in patients with drug-associated torsades de pointes.

BACKGROUND: DNA variants appearing to predispose to drug-associated "acquired" long-QT syndrome (aLQTS) have been reported in congenital long-QT disease genes. However, the incidence of these genetic risk factors has not been systematically evaluated in a large set of patients with aLQTS. We have previously identified functionally important DNA variants in genes encoding K+ channel ancillary subunits in 11% of an aLQTS cohort. METHODS AND RESULTS: The coding regions of the genes encoding the pore-forming channel proteins KvLQT1, HERG, and SCN5A were screened in (1) the same aLQTS cohort (n=92) and (2) controls, drawn from patients tolerating QT-prolonging drugs (n=67) and cross sections of the Middle Tennessee (n=71) and US populations (n=90). The frequency of three common nonsynonymous coding region polymorphisms was no different between aLQTS and control subjects, as follows: 24% versus 19% for H558R (SCN5A), 3% versus 3% for R34C (SCN5A), and 14% versus 14% for K897T (HERG). Missense mutations (absent in controls) were identified in 5 of 92 patients. KvLQT1 and HERG mutations (one each) reduced K+ currents in vitro, consistent with the idea that they augment risk for aLQTS. However, three SCN5A variants did not alter I(Na), which argues that they played no role in the aLQTS phenotype. CONCLUSIONS: DNA variants in the coding regions of congenital long-QT disease genes predisposing to aLQTS can be identified in approximately 10% to 15% of affected subjects, predominantly in genes encoding ancillary subunits.

Alleles↗

PubMed2002

Delayed minocycline but not delayed mild hypothermia protects against embolic stroke.

BACKGROUND: Inflammatory reactions occurring in the brain after ischemia may contribute to secondary damage. In the present study, effects of minocycline, an anti-inflammatory agent, alone or in combination with mild hypothermia on focal embolic cerebral ischemia have been examined. METHODS: Focal ischemic injury was induced by embolizing a preformed clot into the middle cerebral artery (MCA). Infarction volume was measured at 48 h after the injury. Mortality was also recorded. RESULTS: Delayed administration of minocycline alone or delayed minocycline plus delayed mild hypothermia reduced the infarction volume significantly. However, delayed mild hypothermia alone was not protective and delayed mild hypothermia in combination with minocycline did not show any additive effect. CONCLUSIONS: These results suggest that minocycline is beneficial in focal ischemic brain injury, and the lack of the enhanced neuroprotection may be due to the brief exposure to hypothermia.

Animals↗

PubMed2002

Synchronizing chaotic dynamics with uncertainties based on a sliding mode control design.

The synchronization of two chaotic systems with uncertainties is studied in this paper. A feedback controller is provided based on a sliding mode control design. A kind of extended state observer is used to compensate for the systems' uncertainties, such as the structure difference or parameter mismatching, using only the available synchronizing error. Then the feedback controller becomes physically realizable based on the states of the observer, and can be used to synchronize two continuous chaotic systems. Illustrative examples of the synchronization of Duffing and Van der Pol oscillators as well as two Lorenz systems with parameter mismatching are proposed to show the effectiveness of this method.

Journal Article↗

PubMed2002

Heterotrimeric GTP-binding proteins in the lacrimal acinar cell endomembrane system.

Secretagogues accelerate traffic in the lysosomal and basal-lateral pathways, as well as in the regulated apical secretory pathway, of lacrimal acinar cells. It has been proposed that alterations of protein segregation in compartments where these traffic pathways intersect may influence autoimmune responses. Heterotrimeric GTP-binding proteins couple secretagogue receptor ligand binding to activation of intracellular signaling cascades, but they are also suggested to participate in endomembrane traffic phenomena. Distributions of G(o), G(i3), G(q), G(11), and two G(s)isoforms were mapped in reconstituted lacrimal acini by confocal immunofluorescence microscopy and in lysates of the reconstituted acini by analytical subcellular fractionation. All G proteins examined were detected at low levels in isolated compartments (blm(i,j)) believed to represent the basal-lateral plasma membrane. G(i3), G(11), and the G(s)isoforms were concentrated in a series of isolated compartments believed to be related to domains of a basal-lateral endosome with sorting and recycling functions (ble-s/r(i,j,k)), a distinct endosomal compartment with basal-lateral membrane-like composition (e-blml), and domains of the trans-Golgi network believed to be involved in traffic to and from the basal-lateral membrane (tgn-blmr). G(o)and G(q)were concentrated in compartments believed to represent a mixture of immature and mature secretory vesicle membranes (isvm and svm) and domains of the trans-Golgi network compartment believed to mediate traffic to secretory vesicles (tgn-svr) and to pre-lysosomes (tgn-lr). Confocal fluorescence microscopy confirmed the presence of both basal-lateral membrane and intracellular pools of the G proteins. Stimulation with 10 microM carbachol for 20min caused a component of the G(o)to redistribute away from the isvm+svm; components of the G(i3), G(q), and G(s)to redistribute away from the tgn-svr+tgn-lr; and a component of the G(i3)to redistribute away from the ble-blml+tgn-blmr. Thus, these proteins may participate in endomembrane traffic steps activated by cholinergic stimulation in addition to playing their classical roles in plasma membrane signal transduction.

Animals↗

PubMed2002

Cardiac-enriched LIM domain protein fhl2 is required to generate I(Ks) in a heterologous system.

OBJECTIVE: Co-expression of the KvLQT1 and minK potassium channel subunits is required to recapitulate I(Ks), the slow component of the cardiac delayed rectifier current, and mutations in either gene cause the congenital Long QT syndrome. It is becoming increasingly well-recognized that multiprotein channel complexes containing proteins capable of modulating channel function assemble at the plasma membrane. Thus, the aim of our study was to identify proteins involved in I(Ks) modulation. METHODS AND RESULTS: Using a yeast-two-hybrid screen with the intracytoplasmic C-terminus of minK as bait, we identified the cardiac-enriched four-and-a-half LIM domain-containing protein (fhl2) as a potential minK partner. We show interaction between the two proteins in GST pulldown assays and demonstrate overlapping subcellular localization using immunocytochemistry of transfected cells supporting a potential interaction. At the functional level, expression of KvLQT1and minK in HEK cells, which lack endogenous fhl2 protein, generated I(Ks) only when fhl2 was co-expressed. By contrast, in CHO-K1 cells, which express fhl2 endogenously, I(Ks) was suppressed by anti-fhl2 antisense which did not affect the currents generated by KvLQT1alone. CONCLUSION: These data indicate that at least in heterologous cells, the generation of I(Ks) requires fhl2 as an additional protein component.

Animals↗

PubMed2002

The identification and subcellular localization of human MRK.

A novel human kinase gene, human MRK (hMRK), was cloned by using degenerate RT-PCR. The hMRK encoded a putative 632 amino acids protein and was highly homologous to rat MRK (rMRK) in the entire coding region. The hMRK was located at chromosome 6p12.3 by RH-PCR analysis. The hMRK was generally expressed a single approximately 6.3 kb transcript at a low level in a variety of tissues except at a high level in testis. The full-length hMRK protein was fused to C-terminal of GFP and expressed in Hela cells. The fluorescence microscopy results identified its nuclear localization.

Amino Acid Sequence↗

PubMed2002

Therapeutic effects of NaFeEDTA-fortified soy sauce in anaemic children in China.

The therapeutic effects of NaFeEDTA-fortified soy sauce on anaemic students were investigated. Three hundred and four iron-deficient anaemic school children (11-17 years) were randomly assigned to three treatment groups: control group (consuming non-fortified soy sauce), low-NaFeEDTA group (consuming fortified soy sauce, providing 5 mg Fe/day) and high-NaFeEDTA group (consuming fortified soy sauce, providing 20 mg Fe/day). Blood haemoglobin (Hb) levels were determined before and after 1 month, 2 months and 3 months of intervention. In addition, serum iron (SI), serum ferritin (SF), free erythrocytic porphyrin (FEP), total iron binding capability (TIBC) and transferritin (TF) were measured before and after consumption of soy sauce for 3 months. The results obtained herein show that the parameters measured were not changed remarkably within the 3-month intervention in the control group (P < 0.05). However, increased Hb, SI, SF and TF levels and decreased TIBC and FEP levels were observed in both the high-NaFeEDTA group (P <0.01) and the low-NaFeEDTA group (P < 0.05). The effectiveness of iron intervention in the low-NaFeEDTA group and high-NaFeEDTA group had no statistical significance after 3 months. It was concluded that nutritional intervention for anaemic students using NaFeEDTA-fortified soy sauce could play a positive role in the improvement of iron status and control of anaemia.

Adolescent↗

PubMed2002

Glycoprotein IIb/IIIa antagonist, murine 7E3 F(ab') 2, and tissue plasminogen activator in focal ischemia: evaluation of efficacy and risk of hemorrhage with combination therapy.

Tissue hypoperfusion during cerebral ischemia results from occlusion of large and small vessels. Combination treatment strategies using fibrinolytics to thrombolyse an embolic clot and antiplatelet agents to prevent reocclusion and the formation of new platelet thrombi in the microcirculation may offer advantages over single-agent therapy. The authors report on the effects of tissue plasminogen activator (rt-PA), a glycoprotein (GP) IIb/IIIa receptor antagonist, 7E3 F(ab') 2, or a combination of the two agents in a focal embolic model of cerebral ischemia in Wistar rats. Focal ischemia was produced by introducing an autologous thrombus into the right side middle cerebral artery. Forty-six male Wistar rats were randomly divided into 6 groups: control (n = 8), 7E3 F(ab') 2 (n = 9, 6 mg/kg), rt-PA (n = 9, 10 mg/kg), rt-PA (n = 6, 20 mg/kg), and 7E3 F(ab') 2 with either 10 mg/kg (n = 10) (low-dose combination) or 20 mg/kg (n = 6) (high-dose combination) rt-PA. Evaluation of neurobehavioral scores, cerebral angiography, bleeding time, and measurement of brain infarction volume were used to determine efficacy. All actively treated groups showed a significant reduction in the infarct volume. Animals treated with 7E3 F(ab') 2 showed reduced infarction volumes (24.0 +/- 5.1%) compared with controls (42.43 +/- 5.6%, P < 0.02). Treatment with rt-PA significantly reduced infarction volume (20.7 +/- 3.3, = 0.01) at 10 mg/kg and at 20 mg/kg (19.5 +/- 8.2%, P < 0.05). Compared with vehicle-treated animals, the low-dose combination (16.4 +/- 5.5, P < 0.003) and high-dose combination (23.7 +/- 6.2%, P < 0.05) showed significant reduction in infarction volume. Cerebral angiography revealed significantly better recanalization in the combination group (5/6 animals in the high dose and 4/6 in low dose) compared with animals treated with 7E3 F(ab') 2 (3/10) or rt-PA alone (2/6). Bleeding time significantly increased from 11.25 +/- 1.9 minutes in the control group to 17 +/- 3.1 minutes in the rt-PA group, 24.5 +/- 2.6 minutes in the 7E3 F(ab') 2 group, 25.7 +/- 3.1 minutes in the low-dose combination group, and 32.5 +/- 4.7 minutes in the high-dose combination group. The incidence of intercerebral hemorrhage was highest in the high-dose combination group (6 of 6 animals) and lowest in the single treatment with 7E3 F(ab') 2 alone (1 of 10 animals) ( P < 0.05). Our data show that murine 7E3 F(ab') 2 alone has therapeutic effects when used after cerebral ischemia. Although this study suggests that higher doses of thrombolytic combined with anti-GPIIb/IIIa therapy may increases the risk of intracranial hemorrhage, the data also support the notion that anti-GPIIb/IIIa agents can safely be combined with low doses of thrombolytic agent to produce significant attenuation of neuronal damage with no increase in the incidence of cerebral hemorrhage.

Animals↗

PubMed2002

Effects of nonpeptide V(1) vasopressin receptor antagonist SR-49059 on infarction volume and recovery of function in a focal embolic stroke model.

BACKGROUND AND PURPOSE: Cerebral edema develops very early after the onset of focal cerebral ischemia and may be a major factor in early disability after an acute ischemic stroke. There have been very limited studies on the usefulness of antiedemic agents as neuroprotective agents in the setting of focal cerebral ischemia. We tested the neuroprotective effects of a new potent nonpeptide vasopressin receptor V(1) antagonist, SR-49059, in a focal embolic stroke model in rats. METHODS: Focal ischemic injury was induced by embolizing a preformed clot into the middle cerebral artery (MCA). Infarction volume was measured at 48 hours after the MCA occlusion. Neurological deficits, ischemic brain edema, seizure activity, and mortality and hemorrhage rates were also documented. RESULTS: Treatment with SR-49059 (2 mg/kg), initiated immediately after MCA occlusion, significantly reduced infarction volume (P<0.05) measured at 48 hours after the arterial occlusion. In animals in which the treatment was delayed for 1 hour after MCA occlusion, infarction volume was also reduced significantly (P<0.05). Infarction volume in the rats that received the drug at 3 or 6 hours after MCA occlusion was not different from that in the vehicle-treated group. Treatment with SR-49059, when started early after the arterial occlusion, also reduced neurological deficits and ischemic brain edema. Injection of drug at a higher dose (30 mg/kg) also reduced infarction volume and improved functional recovery but was not superior to the lower dose (2 mg/kg) when the drug was administrated at 1 hour after MCA occlusion. CONCLUSIONS: Our data show that the selective vasopressin receptor antagonist SR-49059 is a potent neuroprotective agent when used early after onset of arterial occlusion in an embolic focal ischemia model in rats. Further studies are needed in stroke models to better understand its neuroprotective properties when used alone or in combination with thrombolysis.

Animals↗

PubMed2002

KIAA0202, a human septin family member, interacting with hPFTAIRE1.

hPFTAIRE1 is a member of Cdc2-related kinase family localized in cytoplasm. To search its substrates and regulatory proteins, the hPFTAIRE1 was fused to LexA and used as bait to screen a human brain LexA two-hybrid library. In this screening, 7 hPFTAIRE1 interacting proteins, including KIAA0202, were obtained. The interaction between the KIAA0202 and the hPFTAIRE1 was confirmed by using immunoprecipitation. The KIAA0202 is a 508 aa protein and is a member of septin family. The central portion of the KIAA0202 is a GTP-CDC domain, which is conserved among almost all septins. Its C-terminus is a coiled-coil structure and its N-terminus is a variable region. Our results suggest that the KIAA0202 may play important roles in functional regulation of hPFTAIRE1.

Amino Acid Sequence↗

PubMed2002

Novel mitochondrial 16S rRNA mutation, 3200T-->C, associated with adult-onset type 2 diabetes.

OBJECTIVE: To investigate the role of a potential diabetes-related mitochondrial region, which includes two previously reported mutations, 3243A-->G and 3316G-->A, in Chinese patients with adult-onset type 2 diabetes. METHODS: A total of 277 patients and 241 normal subjects were recruited for the study. Mitochondrial nt 3116 - 3353, which spans the 16S rRNA, tRNA(leu(UUR)) and the NADH dehydrogenase 1 gene, were detected using polymerase chain reaction (PCR), direct DNA sequencing, PCR-restriction fragment length polymorphism and allele-specific PCR. Variants were analyzed by two-tailed Fisher exact test. The function of the variants in 16S rRNA were predicted for minimal free energy secondary structures by RNA folding software mfold version 3. RESULTS: Four homoplasmic nucleotide substitutions were observed, 3200T-->C, 3206C-->T, 3290T-->C and 3316G-->A. Only the 3200T-->C mutation is present in the diabetic population and absent in the control population. No statistically significant associations were found between the other three variants and type 2 diabetes. The 3200T-->C and 3206C-->T nucleotide substitutions located in 16S rRNA are novel variants. The 3200T-->C caused a great alteration in the minimal free energy secondary structure model while the 3206C-->T altered normal 16S rRNA structure little. CONCLUSIONS: The results suggest that the 3200T-->C mutation is linked to the development of type 2 diabetes, but that the other observed mutations are neutral. In contrast to the Japanese studies, the 3316G-->A does not appear to be related to type 2 diabetes.

Age of Onset↗

PubMed2002

[The influence of recombinant human growth hormone on the apoptosis and intestinal mucosal structure in severely scalded rats].

OBJECTIVE: To explore the influence of recombinant human growth hormone (rhGH) on the apoptosis and intestinal mucosal structure in severely scalded rats. METHODS: Thirty male Wistar rats were randomly divided into three groups, i.e. control, scalding and rhGH groups. The rats in scalding and rhGH groups were inflicted with 25% TBSA III degree scalding on the back and immediately followed by intraperitoneal injection of dexamethasone (80 mg/kg). The scalded rats were administered with normal saline and rhGH (1.33 IU.kg(-1).d(-1)) since 2 postburn hours (PBHs), respectively in the last two groups. The changes of the apoptosis rate, the intestinal mucosal proliferative index (PI) and epithelial ultrastructure and the intestinal mucosal pathomorphology of the distal end of ileal mucosal tissue were observed on 30 and 96 PBHs. RESULTS: The intestinal mucosa morphology and epithelia in scalding group were severely injured but were significantly ameliorated by rhGH to near those in control group. The PI in rhGH and scalding groups at 30 PBHs was evidently higher that that in control group (P < 0.05 - 0.01). But the PI exhibited no obvious difference between scalding and rhGH groups. While the PI in rhGH group at 96 PBHs was obviously higher than that in both scalding and control groups (P < 0.01). The intestinal mucosal epithelial apoptotic rate in scalding group was significantly higher than that in control group (P < 0.01), while that in rhGH group was evidently lower than that in scalding and control groups (P < 0.05 - 0.01). CONCLUSION: rhGH could promote postburn intestinal mucosa epithelial proliferation in slow - action manner and inhibit intestinal mucosal epithelial apoptosis with rapid and obvious effects. As a result, the intestinal mucosal epithelial injury could be ameliorated by rhGH by means of its inhibiting roles and the normal morphological structure of intestinal mucosa was maintained ad hoc.

Animals↗

PubMed2001

Construction of Candida albicans Two-hybrid Library and Screening for Proteins Interacting with Crk1.

In order to study interactions among proteins involved in Candida albicans morphorgenesis, C.albicans genomic DNA was digested with Sau3AI and fused to activating domain(AD) of LEXA to construct an AD-fused C.albicans genomic DNA expression library. The library contained 7.7x10(4) independent clones and included 1.2x10(5) kb DNA which was 10 fold of the C.albicans whole genomic DNA. The CRK1 gene encodes a CDC2-related protein, that was involved in morphorgenesis of C.albicans. The Crk1 fused to DNA binding domain of LexA was used as the bait to screen the LexA library. Among 9x10(5) transformants, eight Leu and LacZ double positive clones were selected. With restriction enzyme analysis, three kinds of fragments were identified. The clones NJ1, NJ2, NJ3 were sequenced and analyzed with BLAST program. It was found that NJ1, NJ2, NJ3 were homologs of S.cerevisiae gene STI1, RET2 and NFI1, respectively. The kinase domain of Crk1(Crk1N)interacted weakly with protein encoded by NJ1, while the noncatalytic domain of Crk1(Crk1C) interacted strongly with proteins encoded by NJ2 and NJ3. The interaction of NJ3 and Crk1C was verified by the coimmunoprecipition of NJ3-HA with Crk1C-LexA. These proteins may be involved in maturation, transport, localization, and activity regulation of the Crk1.

Journal Article↗

PubMedDate not supplied

Clot fragments formed from original thrombus obstruct downstream arteries in the ischemic injured brain.

OBJECTIVE: Embolic occlusion of the middle cerebral artery (MCA) leads to distal perfusion deficits as the vessel is recanalized. However, the mechanism for the perfusion deficits is not fully understood. The authors examined whether distal movement of fragments formed from the original thrombus contributes to the perfusion deficits. METHODS: In the first series, they studied whether the reduction in perfusion deficits is due to the dissolution of the original clots embolized or due to collateral perfusion. In the second series, they studied whether fragments formed from the original clots move to distal arterial system. In the third series, they studied whether plasminogen activator plays a role in the thrombolysis following ischemia. RESULTS: Occlusion of MCA permanently resulted in large perfusion deficits in the ipsilateral hemisphere, and these perfusion deficits did not change significantly after the occlusion. In contrast, perfusion deficits reduced significantly in a model of transient MCA occlusion. The numbers of fragments formed from the original clots increased gradually after the MCA occlusion in the ischemic injured brain. In addition, expression of urokinase plasminogen activator was also upregulated. CONCLUSION: The present study thus reveals the mechanisms of the downstream arterial occlusion following the dissolution of original thrombus.

Animals↗