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Hong Jiang

Publications and source records attributed to Hong Jiang.

At least 73 records · Page 4Linked to original sources
PubMed2005

Second-order Kohn-Sham perturbation theory: correlation potential for atoms in a cavity.

Second-order perturbation theory based on the Kohn-Sham Hamiltonian leads to an implicit density functional for the correlation energy E(c) (MP2), which is explicitly dependent on both occupied and unoccupied Kohn-Sham single-particle orbitals and energies. The corresponding correlation potential v(c) (MP2), which has to be evaluated by the optimized potential method, was found to be divergent in the asymptotic region of atoms, if positive-energy continuum states are included in the calculation [Facco Bonetti et al., Phys. Rev. Lett. 86, 2241 (2001)]. On the other hand, Niquet et al., [J. Chem. Phys. 118, 9504 (2003)] showed that v(c) (MP2) has the same asymptotic -alpha(2r(4)) behavior as the exact correlation potential, if the system under study has a discrete spectrum only. In this work we study v(c) (MP2) for atoms in a spherical cavity within a basis-set-free finite differences approach, ensuring a completely discrete spectrum by requiring hard-wall boundary conditions at the cavity radius. Choosing this radius sufficiently large, one can devise a numerical continuation procedure which allows to normalize v(c) (MP2) consistent with the standard choice v(c)(r-->infinity)=0 for free atoms, without modifying the potential in the chemically relevant region. An important prerequisite for the success of this scheme is the inclusion of very high-energy virtual states. Using this technique, we have calculated v(c) (MP2) for all closed-shell and spherical open-shell atoms up to argon. One finds that v(c) (MP2) reproduces the shell structure of the exact correlation potential very well but consistently overestimates the corresponding shell oscillations. In the case of spin-polarized atoms one observes a strong interrelation between the correlation potentials of the two spin channels, which is completely absent for standard density functionals. However, our results also demonstrate that E(c) (MP2) can only serve as a first step towards the construction of a suitable implicit correlation functional: The fundamental variational instability of this functional is recovered for beryllium, for which a breakdown of the self-consistent Kohn-Sham iteration is observed. Moreover, even for those atoms for which the self-consistent iteration is stable, the results indicate that the inclusion of v(c) (MP2) in the total Kohn-Sham potential does not lead to an improvement compared to the complete neglect of the correlation potential.

Algorithms↗
PubMed2005

Expression of transcription factor E2F1 and telomerase in glioblastomas: mechanistic linkage and prognostic significance.

BACKGROUND: Several tumor suppressor pathways have been identified as modulators of telomerase function. We examined the functional role of the retinoblastoma-E2F1 pathway in regulating telomerase activity in malignant gliomas. METHODS: Adenovirus vectors were used to transfer cDNAs into human glioblastoma and sarcoma cells. Telomerase activity was assessed with a telomere repeat amplification protocol. Promoter activity in cancer cells was assessed with promoter-luciferase reporter constructs. Promoter binding was assessed with the chromatin immunoprecipitation (ChIP) assay. We isolated astrocytes from E2F1 transgenic mice and normal mice for in vivo studies. We evaluated the expression of E2F1 and hTERT (the catalytic subunit of human telomerase) mRNAs by reverse transcriptase-polymerase chain reaction and proteins in human glioblastoma samples by immunoblot analysis. Associations between survival among 61 glioblastoma multiforme patients and expression of E2F1 and hTERT mRNA and protein were examined with Kaplan-Meier analysis, the log-rank test, and Cox proportional hazards regression models. All statistical tests were two-sided. RESULTS: Ectopic E2F1 expression increased hTERT promoter activity in cancer cells. We detected an interaction between E2F1 protein and the hTERT promoter. Transgenic E2F1 astrocytes contained functional telomerase protein. E2F1 mRNA expression and hTERT mRNA expression were statistically significantly correlated in human glioblastoma specimens (R = .8; P < .001). Longer median survival was statistically significantly associated with lower E2F1 mRNA expression in tumors (103.6 weeks) rather than with higher expression (46.1 weeks) (difference = 57.5 weeks; 95% confidence interval [CI] = 14.7 to 159.7; log-rank P = .002). E2F1 mRNA was the only factor that was statistically significantly associated with overall survival in a multivariable model (P = .04). Among 27 patients with glioblastoma multiforme samples, the expression of E2F1 protein was statistically significantly associated with survival (log-rank P < .001). CONCLUSIONS: E2F1 may participate in telomerase activity regulation in malignant glioma cells. Its expression appears to be strongly associated with the survival of patients with malignant brain tumors.

Animals↗
PubMed2005

P-glycoprotein deficiency at the blood-brain barrier increases amyloid-beta deposition in an Alzheimer disease mouse model.

Accumulation of amyloid-beta (Abeta) within extracellular spaces of the brain is a hallmark of Alzheimer disease (AD). In sporadic, late-onset AD, there is little evidence for increased Abeta production, suggesting that decreased elimination from the brain may contribute to elevated levels of Abeta and plaque formation. Efflux transport of Abeta across the blood-brain barrier (BBB) contributes to Abeta removal from the brain. P-glycoprotein (Pgp) is highly expressed on the luminal surface of brain capillary endothelial cells and contributes to the BBB. In Pgp-null mice, we show that [I]Abeta40 and [I]Abeta42 microinjected into the CNS clear at half the rate that they do in WT mice. When amyloid precursor protein-transgenic (APP-transgenic) mice were administered a Pgp inhibitor, Abeta levels within the brain interstitial fluid significantly increased within hours of treatment. Furthermore, APP-transgenic, Pgp-null mice had increased levels of brain Abeta and enhanced Abeta deposition compared with APP-transgenic, Pgp WT mice. These data establish a direct link between Pgp and Abeta metabolism in vivo and suggest that Pgp activity at the BBB could affect risk for developing AD as well as provide a novel diagnostic and therapeutic target.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2005

Developments in ghrelin biology and potential clinical relevance.

The spiropiperidine, MK0677, has been exploited to characterize and expression clone the growth hormone secretagogue receptor (GHS-R). Cloning of this receptor led to identification of its natural ligands, ghrelin and adenosine. Targeted disruption of the Ghsr gene demonstrated unambiguously that the GH-releasing and orexigenic properties of ghrelin are dependent on Ghsr expression and that the orexigenic signal is mediated through neuropeptide Y and agouti-related peptide neurons. This review summarizes new developments in our understanding of the physiological roles of ghrelin and its receptor (GHS-R). Recent discoveries of the effects of ghrelin on the thymus and proinflammatory and chemotactic cytokine pathways stimulate renewed interest in potential clinical applications, which include age-associated disorders, such as metabolic disease, sarcopenia, congestive heart failure, atherosclerosis and anorexia.

Animals↗
PubMed2005

Deletion of Abca1 increases Abeta deposition in the PDAPP transgenic mouse model of Alzheimer disease.

Apolipoprotein E (apoE) genotype has a major influence on the risk for Alzheimer disease (AD). Different apoE isoforms may alter AD pathogenesis via their interactions with the amyloid beta-peptide (Abeta). Mice lacking the lipid transporter ABCA1 were found to have markedly decreased levels and lipidation of apoE in the central nervous system. We hypothesized that if Abca1-/- mice were bred to the PDAPP mouse model of AD, PDAPP Abca1-/ mice would have a phenotype similar to that of PDAPP Apoe+/- and PDAPP Apoe-/- mice, which develop less amyloid deposition than PDAPP Apoe+/+ mice. In contrast to this prediction, 12-month-old PDAPP Abca -/- mice had significantly higher levels of hippocampal Abeta, and cerebral amyloid angiopathy was significantly more common compared with PDAPP Abca1+/+ mice. Amyloid precursor protein (APP) C-terminal fragments were not different between Abca1 genotypes prior to plaque deposition in 3-month-old PDAPP mice, suggesting that deletion of Abca1 did not affect APP processing or Abeta production. As expected, 3-month-old PDAPP Abca1-/- mice had decreased apoE levels, but they also had a higher percentage of carbonate-insoluble apoE, suggesting that poorly lipidated apoE is less soluble in vivo. We also found that 12-month-old PDAPP Abca1-/- mice had a higher percentage of carbonate-insoluble apoE and that apoE deposits co-localize with amyloid plaques, demonstrating that poorly lipidated apoE co-deposits with insoluble Abeta. Together, these data suggest that despite substantially lower apoE levels, poorly lipidated apoE produced in the absence of ABCA1 is strongly amyloidogenic in vivo.

ATP Binding Cassette Transporter 1↗
PubMed2005

Spinocerebellar ataxia type 6 in Mainland China: molecular and clinical features in four families.

The hereditary spinocerebellar ataxias (SCAs) are a clinically and genetically heterogeneous group of neurodegenerative disorders. The genes causing 11 of these diseases have been identified. To date, there is no report of SCA type 6 (SCA6) in Mainland Chinese. Using a molecular approach, we investigated SCA6 as well as other SCA subtype in 120 Mainland Chinese families with dominantly inherited ataxias and in 60 Mainland Chinese patients with sporadic ataxias. Clinical and molecular features of SCA6 were further characterized in 13 patients from 4 families. We found that SCA3/MJD was the most common type of autosomal dominant SCA in Mainland Chinese, accounting for 83 patients from 59 families (49.2%), followed by SCA2 (8 [6.7%]), SCA1 (7 [5.8%]), SCA6 (4 [3.3%]), SCA7 (1 [0.8%]), SCA8 (0%), SCA10 (0%), SCA12 (1 [0.8%]), SCA14 (0%), SCA17 (0%) and DRPLA (0%). The genes responsible for 40 (33.3%) of dominantly inherited SCA families remain to be determined. Among the 60 patients with sporadic ataxias in the present series, 3 (5.0%) were found to harbor SCA3 mutations, whereas none were found to harbor SCA6 mutations. In the 4 families with SCA6, we found significant anticipation in the absence of genetic instability on transmission. This is the first report of geographic cluster of families with SCA6 subtype in Mainland China.

Ataxin-3↗
PubMed2005

[Analysis of the pathological features and gene mutations of Chinese patients with Charcot-Marie-Tooth disease].

OBJECTIVE: To analyze the relationship of the pathological features and the gene mutations of Chinese patients with Charcot-Marie-Tooth disease. METHODS: The clinical manifestations and pathological investigations of 26 Chinese patients with Charcot-Marie-Tooth disease, 17 males and 9 females, aged 19.0 (4 - 49), with an average disease course of 0.5 - 30 years, 16 being with CMT1 type and 10 being with CMT2 type. Biopsy of sural nerve was conducted in 26 cases, and gene diagnosis was carried out in 13 cases. RESULTS: Five patients were with peripheral myelin protein-22 (PMP22) duplication, 4 of which showed demyelination, 4 of which showed incrassation of myelin sheath, and two of which showed "onion bulb" change without axonal denaturation. Four cases were with connexin 32 (Cx32) point mutations, 3 of which showed demyelination and one of which showed incrassation of myelin sheath and absence of axonal denaturation. The 2 patients with heat shock protein 22 (Hsp22) and heat shock protein 27 (Hsp27) point mutations both showed axonal atrophy, axonal loss and axonal regeneration. CONCLUSION: The pathological findings of the Chinese CMT patients performed by mutation screening were not completely consistent with the pathological features reported abroad. The results of the mutation screening are consistent with the pathological features; mutation screening has the character of high accuracy, little harm and helps diagnose early, so it is suggested to be performed widely clinically, especially to the patients who has family history or to their lineal relatives.

Adolescent↗
PubMed2005

Changes of IK, ATP current density and allosteric modulation during chronic atrial fibrillation.

BACKGROUND: Atrial fibrillation (AF) is the most common supraventricular arrhythmia in clinical practice. Chronic atrial fibrillation (CAF) is associated with ionic remodeling. However, little is known about the activity of ATP-sensitive potassium current (IK, ATP) during CAF. So we studied the changes of IK, ATP density and allosteric modulation of ATP-sensitivity by intracellular pH during CAF. METHODS: Myocardium samples were obtained from the right auricular appendage of patients with rheumatic heart disease complicated with valvular disease in sinus rhythm (SR) or CAF. There were 14 patients in SR group and 9 patients in CAF group. Single atrial cells were isolated using an enzyme dispersion technique. IK, ATP was recorded using the whole-cell and inside-out configuration of voltage-clamp techniques. In whole-cell model, myocytes of SR and CAF groups were perfused with simulated ischemic solution to elicit IK, ATP. In inside-out configuration, the internal patch membranes were exposed to different ATP concentrations in pH 7.4 and 6.8. RESULTS: Under simulated ischemia, IK, ATP current density of CAF group was significantly higher than in SR group [(83.5 +/- 10.8) vs. (58.7 +/- 8.4) pA/pF, P < 0.01]. IK, ATP of the two groups showed ATP concentration-dependent inhibition. The ATP concentration for 50% current inhibition (IC50) for the SR group was significantly different in pH 7.4 and pH 6.8 (24 vs. 74 micromol/L, P < 0.01). The IC50 did not change significantly in CAF group when the pH decreased from 7.4 to 6.8. CONCLUSIONS: During CAF, IK, ATP current density was increased and its allosteric modulation of ATP-sensitivity by intracellular pH was diminished.

Adenosine Triphosphate↗
PubMed2005

Identification of human fetal liver miRNAs by a novel method.

MicroRNAs (miRNAs) are short 20-25 nucleotides RNA molecules that have been shown to regulate gene expressions in a variety of eukaryotic systems. miRNAs are widespread in eukaryotes and several hundred of miRNAs have been identified, but still a lot of miRNAs have not been detected in various eukaryotic organisms. However, it is not an easy work to clone miRNAs by traditional methods. Here, we describe the identification of 27 miRNAs from a human fetal liver cDNA library by a novel cloning method. Low molecular weight RNA fraction (< or = 200 nt) from fetal liver tissue was extracted, and polyadenylated by poly(A) polymerase. A 5' RNA adaptor was ligated to poly(A)-tailed RNA using T4 RNA ligase. After reverse transcription, the cDNA was amplified by PCR with two adaptor primers. The PCR product with a size about 109 bp was recovered and cloned into T vector. After sequencing, database searching, and expression profiling, 5 novel miRNAs were discovered among other 22 known miRNAs in human fetal liver. These finding indicate that a large diverse population of miRNAs may function to regulate gene expression in hepatocyte.

Cells, Cultured↗
PubMed2005

Eph kinases and ephrins support thrombus growth and stability by regulating integrin outside-in signaling in platelets.

The ability of activated platelets to adhere to each other at sites of vascular injury depends on the integrin alpha(IIb)beta(3). However, as aggregation continues, other signaling and adhesion molecules can contribute as well. We have previously shown that human platelets express on their surface the Eph receptor kinases EphA4 and EphB1 and the Eph kinase ligand ephrinB1. We now show that EphA4 is physically associated with alpha(IIb)beta(3) in resting platelets, increases its surface expression when platelets are activated, and colocalizes with alpha(IIb)beta(3) at sites of contact between platelets. We also show that Eph/ephrin interactions can support the stable accumulation of platelets on collagen under flow and contribute to postengagement "outside-in" signaling through alpha(IIb)beta(3) by stabilizing platelet aggregates and facilitating tyrosine phosphorylation of the beta(3) cytoplasmic domain. beta(3) phosphorylation allows myosin to bind to alpha(IIb)beta(3) and clot retraction to occur. The data support a model in which the onset of aggregation permits Eph/ephrin interactions to occur, after which signaling downstream from ephrinB1 and its receptors favors continued growth and stability of the thrombus by several mechanisms, including positive effects on outside-in signaling through alpha(IIb)beta(3).

Ephrin-B1↗
PubMed2005

Frequency analysis of autosomal dominant spinocerebellar ataxias in mainland Chinese patients and clinical and molecular characterization of spinocerebellar ataxia type 6.

BACKGROUND: Dominantly inherited spinocerebellar ataxia (SCA) is a clinically and genetically heterogeneous group of neurodegenerative disorders. This study was to further assess the frequency of SCA1 (spinocerebellar ataxia type 1), SCA2, SCA3/MJD (spinocerebellar ataxia type 3/Machado-Joseph disease), SCA6, SCA7, SCA8, SCA10, SCA12, SCA14, SCA17 and DRPLA (dentatorubro-pallidoluysian atrophy) in mainland Chinese, and to specifically characterize mainland Chinese patients with SCA6 in terms of clinical and molecular features. METHODS: Using a molecular approach, we investigated SCA in 120 mainland Chinese families with dominantly inherited ataxias and in 60 mainland Chinese patients with sporadic ataxias. Clinical and molecular features of SCA6 were further characterized in 13 patients from 4 families. RESULTS: SCA3/MJD was the most common type of autosomal dominant SCA in mainland Chinese, accounting for 83 patients from 59 families (49.2%), followed by SCA2 [8 (6.7%)], SCA1 [7 (5.8%)], SCA6 [4 (3.3%)], SCA7 [1 (0.8%)], SCA8 (0%), SCA10 (0%), SCA12 (0%), SCA14 (0%), SCA17 (0%) and DRPLA (0%). The genes responsible for 41 (34.2%) of dominantly inherited SCA families remain to be determined. Among the 60 patients with sporadic ataxias in the present series, 3 (5.0%) was found to harbor SCA3 mutations while none was found to harbor SCA6 mutations. In the 4 families with SCA6, significant anticipation was found in the absence of genetic instability on transmission. CONCLUSION: A geographic cluster of families with SCA6 subtype was initially identified in a mainland Chinese population.

Adult↗
PubMed2005

Comparison of hepatic coagulant, fibrinolytic, and anticoagulant functions between Banna Minipig Inbred line and humans.

BACKGROUND: As an ideal candidate for xenotransplantation, the compatibility of physiological porcine organs with those of humans is an essential premise. In this study, we analyzed hepatic coagulant, fibrinolytic, and anticoagulant functions between Banna Minipig Inbreds (BMIs) and humans to evaluate such hepatic compatibility. METHODS: BMI factors II, V, VII, X, and XII were added to the corresponding factor-deficient human plasma to determine prothrombin times (PT) and activated partial thromboplastin times (APTT). Human tissue plasminogen activator (t-PA) was added to both BMI and human plasma to determine plasmin activity. The antithrombin-III (AT-III) activity of plasma was analyzed with the STA-Stago autoanalyzer using an AT-III assay kit. RESULTS: Both PT and APTT were reduced but within normal parameters when BMI factors II, V, VII, X, and XII were added to the corresponding factor-deficient human plasma. The activities of BMI coagulation factors II, V, VII, X, and XII were 3.2, 3.7, 4.7, 2.9, and 4.5 times those of humans, respectively. The activity of plasmin was significantly higher in BMI plasma than in humans when human t-PA was added to both. The normal range of human AT-III activity was 90-108% while BMI AT-III was 124.50 +/- 2.38%. CONCLUSIONS: The activities of coagulation factors and AT-III were higher in BMIs than in humans. BMI coagulation factors XII, VII, and X trigger human intrinsic, extrinsic, and common pathways, respectively, which functioned normally. In addition, BMI plasminogen could be activated by human t-PA.

Adult↗
PubMed2005

[Research on clinical characteristics and ATM gene mutations in Chinese patients with ataxia-telangiectasia].

OBJECTIVE: To investigate the clinical manifestation and mutation characteristics of ATM gene in Chinese patients with ataxia-telangiectasia (AT). METHODS: Sequence variants of the entire coding exons of ATM gene were tested using polymerase chain reaction (PCR), reverse transcription-polymerase chain reaction (RT-PCR), polyacrylamide gel electrophoresis (PAGE) and DNA direct sequencing in two Chinese patients clinically diagnosed as AT. RESULTS: The clinical characteristics of two AT patients were progressive cerebellar ataxia with ages at onset of childhood, ocular-cutaneous telangiectasia and recurrent pulmonary infection due to immuno-deficiency; the serum alpha fetoprotein (AFP) levels were higher than normal, the serum immunoglobin IgA and IgG levels were lower than normal; brain MRI showed cerebellar atrophy, brain SPECT showed cerebellar regional cerebral blood flow (rCBF) hypoperfusion to a certain degree. Totally three nucleotide changes were identified. A missense mutation of G1346C in exon 11, which was a homozygotic mutation, was identified in one patient; a nonsense mutation of G610T in exon 6 combined with a missense mutation of C6679T in exon 47, which was a compound heterozygotic mutation, were identified in the other patient. They were co-segregated with the disease and were localized within the functional domain of ATM gene. CONCLUSION: We have made gene diagnoses for two Chinese AT patients, in which three novel ATM gene mutations were identified.

Ataxia Telangiectasia↗
PubMed2005

C31 enhances voltage-gated calcium channel currents in undifferentiated PC12 cells.

C31, consisting of 31 amino acid residues, is generated from the carboxyl terminal fragments (CTFs) of amyloid precursor protein (APP). It has been shown that C31 causes apoptosis in neurons and is present in brains of Alzheimer disease (AD) patients. Using whole-cell patch clamp techniques, we investigated effects of C31 on voltage-gated calcium channel (VGCC) currents and the protective effects of beta-estradiol on PC12 cells. The results demonstrated that C31 induced a significant increase of the VGCC currents in PC12 cells, which was blocked by beta-estradiol. These results suggest that modulation of intracellular calcium levels by VGCC may in part be involved in C31 induced neuronal death associated with AD.

Animals↗
PubMed2005

The beta-adrenergic blocker carvedilol restores L-type calcium current in a myocardial infarction model of rabbit.

BACKGROUND: Carvedilol, an antagonist of alpha1- and beta-adrenergic receptors, has shown efficacy in reducing all-cause death and arrhythmia death for ischemic heart disease and congestive heart failure in several large-scale trials. It has been found to prevent ventricular remodeling, and recently was reported to reverse down-regulation of Na+ channel in a chronic heart failure model. This study was conducted to investigate whether carvedilol could reverse the ion remodeling in a myocardial infarction model of rabbit. METHODS: After the procedure of coronary ligation, animals were randomized to placebo or carvedilol treatment (5 mg/kg). Action potentials, L-type calcium current (Ica L) and the effect of isoproterenol stimulation on Ica L were measured using whole-cell patch method. Evaluation of the expression of calcium channel subunits was carried out by RT-PCR and Western blot. RESULTS: The results indicate that mean peak Ica L densities (pA/pF) at +10 mV was reduced in postinfarction myocytes (5.33 +/- 0.45, n = 25) compared to sham myocytes (6.52 +/- 0.21, n = 20). Treatment of myocardial infarction rabbits with carvedilol could restore it partially (5.91 +/- 0.39, n = 20, P < 0.05). However, steady-state activation parameters were similar in three groups. With stimulation by isoproterenol (1 micromol/L) Ica L increased in all three groups, but the increase was smaller in postinfarction myocytes. mRNA levels of calcium channel subunit CaA1 gene was decreased but CaB2a, CaB2b and CaB3 mRNA levels did not change after MI. Corresponding change in CaA1 protein was also observed. CONCLUSIONS: The results demonstrate that carvedilol restores Ica L density and reverse the downregulation of CaA1 postinfarction.

Action Potentials↗
PubMed2005

Mutation screening of Cx32 in Han Chinese patients with Charcot-Marie-Tooth disease.

OBJECTIVE: To investigate the Cx32 mutation features and the clinical manifestations of Chinese patients with Charcot-Marie-Tooth disease(CMT). METHODS: Twenty-four of 65 unrelated CMT patients were selected for Cx32 mutation screening after the exclusion of the CMT1A 1.5 Mb duplication and male-to-male transmission. The motor and sensory nerve conduction studies were performed in all probands and most of their affected family members to establish the clinical CMT1 ,CMT2 or CMT intermediate diagnosis. The presence of mutations in the coding region of Cx32 was detected by single-strand conformation polymorphism analysis combined with direct sequencing. RESULTS: We found 7 different point mutations in the coding region of Cx32 in a total of 7 families. All the patients were mildly to moderately affected with a clinical CMT1 or CMT intermediate diagnosis. The mutation Arg15Gln was inherited with X-linked recessive trait in family 1 involved in our study. The Arg75Trp mutation was detected in a family with X-linked dominant CMT and autosomal recessive nonsydromic hearing loss. The clinical phenotype of the Thr188Ala mutation was firstly reported. CONCLUSION: Seven different Cx32 point mutations were detected and the percentage of Chinese CMT families with Cx32 mutation is about 10% in our study. The inheritance model of CMT secondary to Cx32 mutation could be X-linked dominant, X-linked recessive or sporadic. Male patients are usually more severely affected than females with slower nerve conduction velocities. Cx32 mutation screening should be firstly performed in those CMT families without male-to-male transmission and CMT1A duplication.

Charcot-Marie-Tooth Disease↗