Biomedical subjects

Bing Li

Publications and source records attributed to Bing Li.

At least 127 records · Page 7Linked to original sources

PubMed2003

Abnormal anterior cingulum in patients with schizophrenia: a diffusion tensor imaging study.

Diffusion tensor imaging (DTI) can non-invasively examine the molecular diffusion of water in vivo and directly reflects the anatomical integrity of neural fibers in white matter. Fractional anisotropy (FA) can be calculated from DTI data, and utilized to evaluate white matter integrity. DTI was performed on 30 patients with schizophrenia and 19 healthy controls, and their FA values were subsequently measured in multiple brain regions. Statistical analyses revealed that FA values were decreased in the anterior cingulum of schizophrenia subjects. There were no significant differences between patients and controls in any other regions. This study supports the hypothesis that schizophrenia is associated with abnormal white matter integrity of the anterior cingulum.

Adult↗

PubMed2003

ATP-dependent mechanism for coordination of intercellular Ca2+ signaling and renin secretion in rat juxtaglomerular cells.

A change in intracellular Ca2+ is considered to be the common final signaling pathway through which renin secretion is governed. Therefore, information relating to the generation, control, and processing of Ca2+ signaling in juxtaglomerular cells (JG) will be critical for understanding JG cell behavior. In this study, we investigated the means by which JG cells harmonize their intracellular Ca2+ signals and explored the potential role of these mechanisms in renin secretion. Mechanical stimulation of a single JG cell initiated propagation of an intercellular Ca2+ wave to up to 11.9+/-4.1 surrounding cells, and this was prevented in the presence of the ATP-degrading enzyme, apyrase (1.7+/-0.7 cells), or by desensitization of purinergic receptors via pretreatment of cells with ATP (1.8+/-0.9 cells), thus implicating ATP as a mediator responsible for the propagation of intercellular Ca2+ signaling. Consistent with this, JG cells were demonstrated not to express the gap junction protein connexin43, and neither did they possess functional gap junction communication. Furthermore, massive mechanical stretching of JG cells elicited a 3-fold increase in ATP release. Administration of ATP into isolated perfused rat kidneys induced a rapid, potent, and persistent inhibition of renin secretion, together with a transient elevation of renal vascular resistance. ATP (1 mmol/L) caused up to 79% reduction of the renin secretion activated by lowering the renal perfusion flow (P<0.01). Taken together, our results indicate that under mechanical stimulation, ATP functions as a paracellular mediator to regulate renin secretion, possibly through modulating intra- and intercellular Ca2+ signals.

Adenosine Triphosphate↗

PubMed2003

Distribution of glucokinase, glucose transporter GLUT2, sulfonylurea receptor-1, glucagon-like peptide-1 receptor and neuropeptide Y messenger RNAs in rat brain by quantitative real time RT-PCR.

Glucokinase (GK), glucose transporter GLUT2, sulfonylurea receptor-1 (SUR1), glucagon-like peptide-1 receptor (GLP-1R) and neuropeptide Y (NPY) have been proposed to be involved in central glucose sensing or regulation of food intake. In this study, we combined tissue micropunch and real time reverse transcription polymerase chain reaction (RT-PCR), and measured GK, GLUT2, SUR1, GLP-1R and NPY mRNA expression in discrete areas in the hypothalamus and the hindbrain.

ATP-Binding Cassette Transporters↗

PubMed2003

SWI/SNF-dependent chromatin remodeling of RNR3 requires TAF(II)s and the general transcription machinery.

Gene expression requires the recruitment of chromatin remodeling activities and general transcription factors (GTFs) to promoters. Whereas the role of activators in recruiting chromatin remodeling activities has been clearly demonstrated, the contributions of the transcription machinery have not been firmly established. Here we demonstrate that the remodeling of the RNR3 promoter requires a number of GTFs, mediator and RNA polymerase II. We also show that remodeling is dependent upon the SWI/SNF complex, and that TFIID and RNA polymerase II are required for its recruitment to the promoter. In contrast, Gcn5p-dependent histone acetylation occurs independently of TFIID and RNA polymerase II function, and we provide evidence that acetylation increases the extent of nucleosome remodeling, but is not required for SWI/SNF recruitment. Thus, the general transcription machinery can contribute to nucleosome remodeling by mediating the association of SWI/SNF with promoters, thereby revealing a novel pathway for the recruitment of chromatin remodeling activities.

Acetylation↗

PubMed2003

Angiogenesis-independent endothelial protection of liver: role of VEGFR-1.

The vascular endothelium was once thought to function primarily in nutrient and oxygen delivery, but recent evidence suggests that it may play a broader role in tissue homeostasis. To explore the role of sinusoidal endothelial cells (LSECs) in the adult liver, we studied the effects of vascular endothelial growth factor (VEGF) receptor activation on mouse hepatocyte growth. Delivery of VEGF-A increased liver mass in mice but did not stimulate growth of hepatocytes in vitro, unless LSECs were also present in the culture. Hepatocyte growth factor (HGF) was identified as one of the LSEC-derived paracrine mediators promoting hepatocyte growth. Selective activation of VEGF receptor-1 (VEGFR-1) stimulated hepatocyte but not endothelial proliferation in vivo and reduced liver damage in mice exposed to a hepatotoxin. Thus, VEGFR-1 agonists may have therapeutic potential for preservation of organ function in certain liver disorders.

Animals↗

PubMed2003

The Set2 histone methyltransferase functions through the phosphorylated carboxyl-terminal domain of RNA polymerase II.

The histone methyltransferase Set2, which specifically methylates lysine 36 of histone H3, has been shown to repress transcription upon tethering to a heterologous promoter. However, the mechanism of targeting and the consequence of Set2-dependent methylation have yet to be demonstrated. We sought to identify the protein components associated with Set2 to gain some insights into the in vivo function of this protein. Mass spectrometry analysis of the Set2 complex, purified using a tandem affinity method, revealed that RNA polymerase II (pol II) is associated with Set2. Immunoblotting and immunoprecipitation using antibodies against subunits of pol II confirmed that the phosphorylated form of pol II is indeed an integral part of the Set2 complex. Gst-Set2 preferentially binds to CTD synthetic peptides phosphorylated at serine 2, and to a lesser extent, serine 5 phosphorylated peptides, but has no affinity for unphosphorylated CTD, suggesting that Set2 associates with the elongating form of the pol II. Furthermore, we show that set2Delta ppr2Delta double mutants (PPR2 encodes TFIIS, a transcription elongation factor) are synthetically hypersensitive to 6-azauracil, and that deletions in the CTD reduce in vivo levels of H3 lysine 36 methylation. Collectively, these results suggest that Set2 is involved in regulating transcription elongation through its direct contact with pol II.

Antimetabolites↗

PubMed2003

Targeting activity is required for SWI/SNF function in vivo and is accomplished through two partially redundant activator-interaction domains.

The SWI/SNF complex is required for the expression of many yeast genes. Previous studies have implicated DNA binding transcription activators in targeting SWI/SNF to UASs and promoters. To determine how activators interact with the complex and to examine the importance of these interactions, relative to other potential targeting mechanisms, for SWI/SNF function, we sought to identify and mutate the activator-interaction domains in the complex. Here we show that the N-terminal domain of Snf5 and the second quarter of Swi1 are sites of activation domain contact. Deletion of both of these domains left the SWI/SNF complex intact but impaired its ability to bind activation domains. Importantly, while deletion of either domain alone had minor phenotypic effect, deletion of both resulted in strong SWI/SNF related phenotypes. Thus, two distinct activator-interaction domains play overlapping roles in the targeting activity of SWI/SNF, which is essential for its function in vivo.

Cells, Cultured↗

PubMed2003

An artificial somatic-central nervous system-autonomic reflex pathway for controllable micturition after spinal cord injury: preliminary results in 15 patients.

PURPOSE: Neurogenic bladder dysfunction after spinal cord injury (SCI) is a major medical and social problem for which there is no definitive solution. After the successful establishment in animals of a skin-central nervous system-bladder reflex pathway for micturition we performed this procedure on 15 patients with SCI who had 3 years of followup. MATERIALS AND METHODS: A total of 15 male volunteers with hyperreflexic neurogenic bladder and detrusor external sphincter dyssynergia (DESD) caused by complete suprasacral SCI underwent limited hemilaminectomy and ventral root (VR) micro anastomosis, usually between the L5 and S2/3 VRs. The L5 dorsal root was left intact as the trigger of micturition after axonal regeneration. Mean followup was 3 years. All patients underwent urodynamic evaluation before surgery and during followup. RESULTS: Preoperative studies in patients with complete suprasacral SCI revealed hyperreflexic neurogenic bladders and DESD with some differences in storage function during infusion cystometrograms. Of the 15 patients 10 (67%) regained satisfactory bladder control within 12 to 18 months after VR micro anastomosis. Average residual urine decreased from 332 to 31 ml and urinary infection as well as overflow incontinence disappeared. Urodynamic studies revealed a change from detrusor hyperreflexia with DESD and high detrusor pressure to almost normal storage and synergic voiding without DESD. Impaired renal function returned to normal. Two patients (13%) who required a skin stimulator to evoke voiding following the VR anastomosis had partial recovery but more than 100 ml residual urine. One patient was lost to followup and 2 had failure. CONCLUSIONS: An artificial somatic-central nervous system-autonomic reflex arc can be established surgically to provide a novel method for controlling bladder function in patients with complete suprasacral SCI who have hyperreflexic bladder and DESD. Nerve impulses delivered from the efferent neurons of a somatic reflex arc can be transferred to initiate the response of an autonomic effector.

Adult↗

PubMed2003

HCA587 antigen expression in normal tissues and cancers: correlation with tumor differentiation in hepatocellular carcinoma.

The HCA587 gene, identified by serological analysis of recombinant cDNA expression library (SEREX) from a hepatocellular carcinoma (HCC) patient, encodes a new member of cancer-testis antigens. HCA587 mRNA expression in normal tissues and cancers has been previously reported. To estimate its immunogenicity to induce immune response, it is essential to analyze HCA587 expression at the protein level. In this study anti-HCA587 polyclonal antibody, termed "TC-1," was generated, and the expression of HCA587 protein was assessed by immunohistochemical staining in a panel of normal and tumor tissue sections. No HCA587 protein was shown in normal tissues except germ cells in testis and Purkinji cells in cerebellum. In HCC specimens the HCA587 protein was expressed in 37.1% (26 of 70) samples. The expressed protein was either located in the cytoplasm or nucleus depending on the individual samples. More importantly, there appears to be correlation between the tumor differentiation of HCC and HCA587 protein expression, ie, the lower differentiation, the higher percentage of protein expression. Coincidentally, seroreactivity showed that the Ab specific to recombinant HCA587 protein was detected only in the sera of three patients with poorly differentiated HCCs. HCA587 antigen was also expressed in different proportions in melanoma, lymphoma, pancreatic cancer, and lung cancer.

Animals↗

PubMed2003

Calmodulin is involved in heat shock signal transduction in wheat.

The involvement of calcium and calcium-activated calmodulin (Ca(2+)-CaM) in heat shock (HS) signal transduction in wheat (Triticum aestivum) was investigated. Using Fluo-3/acetoxymethyl esters and laser scanning confocal microscopy, it was found that the increase of intracellular free calcium ion concentration started within 1 min after a 37 degrees C HS. The levels of CaM mRNA and protein increased during HS at 37 degrees C in the presence of Ca(2+). The expression of hsp26 and hsp70 genes was up-regulated by the addition of CaCl(2) and down-regulated by the calcium ion chelator EGTA, the calcium ion channel blockers LaCl(3) and verapamil, or the CaM antagonists N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide and chlorpromazine. Treatment with Ca(2+) also increased, and with EGTA, verapamil, chlorpromazine, or trifluoperazine decreased, synthesis of HS proteins. The temporal expression of the CaM1-2 gene and the hsp26 and hsp70 genes demonstrated that up-regulation of the CaM1-2 gene occurred at 10 min after HS at 37 degrees C, whereas that of hsp26 and hsp70 appeared at 20 min after HS. A 5-min HS induced expression of hsp26 after a period of recovery at 22 degrees C after HS at 37 degrees C. Taken together, these results indicate that Ca(2+)-CaM is directly involved in the HS signal transduction pathway. A working hypothesis about the relationship between upstream and downstream of HS signal transduction is presented.

Calcium↗

PubMed2003

Effect of high glucose on nitric oxide production and endothelial nitric oxide synthase protein expression in human glomerular endothelial cells.

BACKGROUND: Hyperglycemia directly contributes to the development of diabetic nephropathy. Nitric oxide (NO), a potent endothelium-derived vasodilator, has been suggested to participate in the regulation of renal blood flow, glomerular filtration rate, and mesangial matrix accumulation. Human vascular endothelial cells are known to exhibit functional heterogeneity, this prompted us to do the first study of NO bioavailability in human glomerular endothelial cells (HGECs), in response to high glucose exposure. METHODS: NO release was examined by detecting nitrite generation by the Griess assay in HGECs exposed to control-level (5.5 mM) and high-level (15, 30 and 60 mM) glucose solutions at various time periods (24, 48 and 72 h) in the presence or absence of L-arginine (1 mM), or superoxide dismutase (SOD) (250 U/ml). In addition, we evaluated the effect of glucose on the expression of endothelial nitric oxide synthase (eNOS) in HGECs by Western blotting. RESULTS: Final levels of nitrite generated in HGECs were reduced significantly, in a time- and concentration-dependent manner, after high glucose exposure. However, Western blot analysis revealed that eNOS protein expression was significantly upregulated at 12 h after exposure to high glucose concentrations (30 mM), reaching a peak at 48 h (twofold increase over baseline levels). The inhibitory effect of high glucose on NO production was restored by the addition of SOD. Addition of L-arginine (1 mM) to external media also reversed the inhibitory effect of high glucose on NO production of HGECs as well. CONCLUSIONS: The present study demonstrated that high glucose increased eNOS protein expression, but decreased NO release finally. Decreased NO bioavailability seems to be associated with overproduction of superoxide and L-arginine deficiency. These findings provide an important clue in clarifying the molecular basis of the mechanisms by which elevated glucose leads to an imbalance between NO and superoxide, resulting in impaired endothelial function. In addition, restoration of NO function by both administration of L-arginine and adequate intake of antioxidants suggests a potential supportive treatment for patients with diabetic nephropathy.

Arginine↗

PubMed2003

Short-term food restriction and refeeding alter expression of genes likely involved in brain glucosensing.

Several genes involved in glucosensing of the endocrine pancreas have been proposed to serve a similar function in the brain. These genes include the glucose transporter-2 (Glut-2) and glucokinase (GK). In addition, the glucagon-like peptide 1 receptor, which serves as a downstream signal modulator in pancreatic glucosensing and centrally alters feeding, is also of interest. We used quantitative real-time RT-PCR to measure changes in hypothalamic and brainstem Glut-2, GK, and Glp-1R expression of these genes induced by food restriction and refeeding. Sprague-Dawley rats were 50% food restricted for 1 day; one-half of the food-restricted rats were refed with chow for 1 hr before sacrifice. In both hypothalamus and brainstem, gene expression of Glut-2, GK, and Glp-1R was significantly lower in refed rats compared with food-restricted rats. The measures of gene expression in two feeding control groups (ad libitum and voluntarily overfed animals) were intermediate between the food-restricted and refed groups, but were not significantly different from each other. The results indicate that putative glucosensing (GK, Glut-2, and Glp-1R) gene expression in the hypothalamus and brainstem is reduced in response to food intake, depending on prior nutritional status.

Animals↗

PubMed2003

Expression, purification and serological analysis of hepatocellular carcinoma associated antigen HCA587 in insect cells.

AIM: In order to assess hepatocellular carcinoma associated antigen HCA587 as a potential target for immunotherapy, the Bac-to-Bac expression system was used to express recombinant protein HCA587 in insect cells. METHODS: The cDNA encoding HCA587 gene was cloned into donor vector pFasBacHtb and recombinant pFasBac Htb-587 was transformed into competent cells DH10Bac. Recombinant Bacmid-587 was transfected into Sf9 insect cells using CELLFECTIN, Recombinant HCA587 protein was produced in Sf9 insect cells after infection with recombinant baculovirus, and was purified using Ni-NTA resin. Sera from HCC patients were also screened using recombinant protein HCA587. RESULTS: The molecular weight of the recombinant protein HCA587 expressed in insect cells was approximately 43kd. Western blot results proved the recombinant protein HCA587 had the similar antigenicity with its native counterpart. Serological analysis told that the rate of seroreactivity to HCA587 was not high in HCC patients. CONCLUSION: The recombinant protein HCA587 was successfully expressed and purified using Bac-to-Bac expression system. It paved the way for generation of specific antibody and investigation of immunohistochemical analysis and immune responses of HCC in the future.

Animals↗

PubMed2003

[Studies on direct and indirect economic burden of disease and related factor in countryside of Qingdao city in 2001].

OBJECTIVE: To study the condition of economic burden of disease in the countryside and to explore the related factors. METHODS: Human capital method and two-step method were used in the calculation of economic burden of disease. RESULTS: The total economic burden of disease among 3359 persons was 3072 225 Yuan. Noncommunicable conditions were accounted for 62.95%, while communicable disease, maternal and perinatal conditions accounted for 24.25%, and injury accounted for 9.83% respectively. The direct economic burden of disease was 1,559,619 Yuan and the indirect economic burden of disease was 1,472,606 Yuan. The economic burden of disease for each person was 914 Yuan. The equal burden of disease among patients with disability and without disability were 3070 Yuan and 680 Yuan respectively (P < 0.001). There was significant difference among different age groups. The influencing factors were found to include having noncommunicable disease, age, disability and the condition of marriage. CONCLUSION: Corresponding policy to cope with conditions of different age groups needs to be developed to reduce the economic burden of disease in the countryside.

Absenteeism↗

PubMed2003

[Complications following gamma knife radiosurgery].

OBJECTIVE: To investigate complication features following gamma knife radiosurgery (GKR), and to assess factors causing complications. METHODS: A retrospective analysis was conducted for 253 patients with intracranial arteriovenous malformation (AVMs), meningiomas, glial neoplasms, germinomas and metastatic cancer, respectively, which were treated with GKR.The incidences of acute, subacute and late complications following GKR were evaluated. Meanwhile, risk factors inducing subacute complications, such as the cell proliferative population of target tissues and location of target in AVM and meningioma, were evaluated, respectively. RESULTS: The subacute complications are the prominent reactions in all the five diseases. There is a significant difference in the incidence rate of subacute complications between early responding tissues and slow responding tissues, central and peripheral AVM, basal and non-basal meningioma. CONCLUSIONS: Subacute complications are the prominent reactions after GKR, and the reactions are almost always reversible. The risk of subacute complications following GKR treatment is correlated to the proliferative cell population in the target tissues and the target location (AVM, meningioma).

Adolescent↗

PubMed2003

[Relationship between the patients' knowledge on hypertension prevention and control and the rate on blood pressure control].

OBJECTIVE: To study the relationship between blood pressure control status and patients' knowledge on hypertension prevention and control among hypertensive patients. METHODS: A total of 726 hypertensives were selected from four community health service centers (2 urban and 2 rural) in Beijing. All subjects were investigated by questionnaires and their blood pressures were measured at the same time. RESULTS: The rate for blood pressure under control (< 140/90 mm Hg, 1 mm Hg = 0.133 kPa) in the rural and urban patients were 46.4% and 23.9% respectively. The control rate increased with the increase of patients' knowledge on prevention and control of hypertension in both urban and rural patients. The cumulative effect of knowledge on hypertension control status could contribute 30.0% to the difference in hypertension control rate between rural and urban patients. CONCLUSION: Patients' knowledge on hypertension control was significantly related to the rate on hypertension control. Health education should be helpful to improve the rate on hypertension control.

Aged↗

PubMed2002

[Primary biliary cirrhosis: an analysis of 153 cases].

OBJECTIVE: To study the clinical, immunological and pathological features of primary biliary cirrhosis (PBC). METHODS: Clinical and laboratory data of 153 patients with PBC treated in our hospital were retrospectively analyzed. Of these patients, 35 underwent hepatic biopsy. RESULTS: Typical manifestations such as itch of skin and hepatosplenomegaly etc. were found in only 39.2% to 46.4% of the patients and jaundice was seen in 84.3%. The serum level of SB was gradually increased while that of CHE decreased along with progression of PBC (P < 0.01). The level of serum Albumin and ALT was significantly lower in late stage than in the early stages (P < 0.05). ALT and CHE were not correlated with SB. AST level was markedly higher in the late stage than in the early stage (P < 0.05). The levels of ALP and GGT rose at the early stage but remarkably decreased at the middle stage (ALP, P < 0.05) and at the late stage (GGT, P < 0.01). The positive rate of AMA was 83.7% and that of M2 69.3%. As for the 35 patients receiving hepatic biopsy, 10 were AMA positive and the other 25 AMA negative. CONCLUSION: More than half of the patients with PBC do not exhibit typical clinical symptoms and over 80% of the cases of PBC can be diagnosed by investigation of clinical features and detection of AMA and M2. For some cases that can not be definitely diagnosed by observation of clinical features, the final diagnosis should be determined by hepatic biopsy.

Adolescent↗

PubMed2002

Vascular endothelial growth factor-induced genes in human umbilical vein endothelial cells: relative roles of KDR and Flt-1 receptors.

OBJECTIVE: This study evaluated the relative roles of the vascular endothelial growth factor (VEGF) receptors KDR and Flt-1 in the mediation of altered gene expression elicited by VEGF. METHODS AND RESULTS: We used mutants of VEGF selective for the KDR and Flt-1 receptors to differentiate gene expression patterns mediated by wild-type VEGF (VEGFwt) in human umbilical vein endothelial cells. RNA was extracted from cells treated for 24 hours with 1 nmol/L of each ligand, and gene expression was monitored by using oligonucleotide arrays (Affymetrix U95A). We report that activation of KDR was sufficient to upregulate all the genes induced by VEGFwt. In contrast, there were no genes selectively upregulated by the Flt-selective mutant. However, high concentrations of the Flt-selective mutant could augment the expression of some genes induced by submaximal concentrations of VEGFwt but not the KDR-selective mutant. CONCLUSIONS: The binding of VEGF to its receptor, KDR, is necessary and sufficient to induce the gene expression profile induced by this growth factor. Furthermore, in human umbilical vein endothelial cells, the Flt-1 receptor appears to act as a decoy receptor, tempering the response to lower concentrations of VEGF.

Cells, Cultured↗