Biomedical subjects

L Jiang

Publications and source records attributed to L Jiang.

At least 199 records · Page 11Linked to original sources

PubMed1997

Electrogenic sulfate/chloride exchange in Xenopus oocytes mediated by murine AE1 E699Q.

Functional evaluation of chemically modified human erythrocytes has led to the proposal that amino acid residue E681 of the band 3 anion exchanger AE1 lies on the anion translocation pathway and is a proton carrier required for H+/SO4(2-) cotransport. We have tested in Xenopus oocytes the functional consequences of mutations in the corresponding residue E699 of mouse AE1. Most mutations tested abolished AE1-mediated Cl- influx and efflux. Only the E699Q mutation increased stilbene disulfonate-sensitive efflux and influx of SO4(2-). E699Q-mediated Cl- influx was activated by elevation of intracellular SO4(2-), but E699Q-mediated Cl- efflux was undetectable. The DNDS (4,4'-dinitrostilbene-2,2'-disulfonic acid) sensitivity of E699Q-mediated SO4(2-) efflux was indistinguishable from that of wt AE1-mediated Cl- efflux. The extracellular anion selectivity of E699Q-mediated SO4(2-) efflux was similar to that of wt AE1-mediated Cl- efflux. The stoichiometry of E699Q-mediated exchange of extracellular Cl- with intracellular SO4(2-) was 1:1. Whereas SO4(2-) injection into oocytes expressing wt AE1 produced little change in membrane potential or resistance, injection of SO4(2-), but not of Cl- or gluconate, into oocytes expression E699Q depolarized the membrane by 17 mV and decreased membrane resistance by 66%. Replacement of bath Cl- with isethionate caused a 28-mV hyperpolarization in SO4(2-)-loaded oocytes expressing E699Q, but had no effect on oocytes expressing wt AE1. Extracellular Cl(-)-dependent depolarization of SO4(2-)-preloaded oocytes was blocked by DNDS. AE1 E699Q-mediated inward current measured in the presence of extracellular Cl- was of magnitude sufficient to account for measured 35SO4(2-) efflux. Thus, AE1 E699Q-mediated SO4(2-)/Cl- exchange operated largely, if not exclusively, as an electrogenic, asymmetric, 1:1 anion exchange. The data confirm the proposal that E699 resides on or contributes to the integrity of the anion translocation pathway of AE1. A single amino acid change in the sequence of AE1 converted electroneutral to electrogenic anion exchange without alteration of SO4(2-)/Cl- exchange stoichiometry.

Animals↗

PubMed1997

Molecular cloning and further characterization of a probable plant vacuolar sorting receptor.

BP-80 is a type I integral membrane protein abundant in pea (Pisum sativum) clathrin-coated vesicles (CCVs) that binds with high affinity to vacuole-targeting determinants containing asparagine-proline-isoleucine-arginine. Here we present results from cDNA cloning and studies of its intracellular localization. Its sequence and sequences of homologs from Arabidopsis, rice (Oryza sativa), and maize (Zea mays) define a novel family of proteins unique to plants that is highly conserved in both monocotyledons and dicotyledons. The BP-80 protein is present in dilated ends of Golgi cisternae and in "prevacuoles," which are small vacuoles separate from but capable of fusing with lytic vacuoles. Its cytoplasmic tail contains a Tyr-X-X-hydrophobic residue motif associated with transmembrane proteins incorporated into CCVs. When transiently expressed in tobacco (Nicotiana tabacum) suspension-culture protoplasts, a truncated form lacking transmembrane and cytoplasmic domains was secreted. These results, coupled with previous studies of ligand-binding specificity and pH dependence, strongly support our hypothesis that BP-80 is a vacuolar sorting receptor that trafficks in CCVs between Golgi and a newly described prevacuolar compartment.

Amino Acid Sequence↗

PubMed1997

Ameliorating effect of erythromycin on bleomycin-induced pulmonary fibrosis: role of alveolar macrophage activation and cytokine release.

The objective of this study was to evaluate the effectiveness of erythromycin (EM) on bleomycin-induced pulmonary fibrosis in rats and its possible mechanisms. Seventy-five rats were divided into three groups. Alveolar macrophages (AM) were harvested through bronchalveolar lavage (BAL) and consecutive changes of tumour necrosis factor-alpha (TNF-alpha) and platelet-derived growth factor (PDGF) in AM supernatant and bronchoalveolar lavage fluid (BALF) were assayed with ELISA and bioassay, respectively. The AM-derived TNF-alpha was elevated on day 3, peaked day 7 and then decreased but remained at higher level until day 28. The AM-derived PDGF was increased on day 3, peaked on day 7 then decreased to non-statistically significant higher level. The TNF-alpha in BALF was increased significantly on day 3 then decreased to normal level; the peak preceded that of AM-derived TNF-alpha. The PDGF in BALF was increased on day 3, peaked on day 7, and then decreased to normal, which exhibited a consecutive change similar to that of AM-derived PDGF. The EM significantly suppressed TNF-alpha and PDGF release by AM, markedly decreased TNF-alpha and PDGF levels in BALF. The EM also lessened the collagen deposition, the lung hydroxyproline comprised 75.44%, 72.72% and 56.24% that of bleomycin-treated group on day 7, 14 and 28, respectively. In conclusion, EM can ameliorate bleomycin-induced pulmonary fibrosis possibly through suppression of TNF-alpha and PDGF as well as the inhibition on accumulation of inflammatory cells in the lung.

Animals↗

PubMed1997

Enterococcus faecalis antigens in human infections.

Genomic libraries of two Enterococcus faecalis strains, OG1RF and TX52 (an isolate from an endocarditis patient), were constructed in cosmid vectors pBeloBAC11 and pLAFRx, and screened with a serum from a rabbit immunized with surface proteins of an E. faecalis endocarditis isolate and sera from four patients with enterococcal endocarditis. Seventy-five cosmid clones reacted with at least two of the sera. Thirty-eight of the 75 immunopositive clones were considered to contain distinct inserts based on their DNA restriction patterns and were chosen for further subcloning into a pBluescript vector. Each sublibrary was screened with one of the five sera, and the DNA sequence of the immunopositive subclones was determined. Analysis of these sequences revealed similarities to a range of proteins, including bacterial virulence factors, transporters, two-component regulators, metabolic enzymes, and membrane or cell surface proteins. Fourteen subclones did not show significant similarity to any sequence in the databases and may contain novel genes. Thirteen of the immunopositive cosmid clones did not yield immunopositive subclones, and one such cosmid clone produced a nonprotein antigen in Escherichia coli.

Antibodies, Bacterial↗

PubMed1997

Secondary regulatory volume increase conferred on Xenopus oocytes by expression of AE2 anion exchanger.

Xenopus oocytes lack volume regulation and Cl/anion-exchange (AE) activity but express endogenous Na+/H+ exchange (NHE). We postulated that expression in oocytes of heterologous anion exchangers might allow regulatory volume increase (RVI) via functional coupling with endogenous NHE. Expression of neither erythroid nor kidney isoforms of AE1 conferred any form of RVI. In contrast, although AE2 expression did not confer primary RVI, it did confer on oocytes secondary RVI, with a requirement for hypotonic swelling before hypertonic shrinkage. This secondary RVI required extracellular Cl- and Na+, was blocked by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid and amiloride, was bumetanide insensitive, and was blocked by prevention of intracellular alkalinization, all properties consistent with functional coupling of AE2-mediated Cl-/HCO3- exchange and endogenous NHE. RVI was unaffected by CO2-HCO3- or by partial oocyte Cl- depletion and was unrelated to the rate of oocyte shrinkage. Prior hypotonic swelling did not significantly alter subsequent hypertonic stimulation of AE2-mediated 36Cl influx or efflux. We conclude that heterologous AE2 expression suffices to confer volume regulation on Xenopus oocytes that lack intrinsic volume-regulatory mechanisms.

Alkalies↗

PubMed1997

NH4Cl activates AE2 anion exchanger in Xenopus oocytes at acidic pHi.

In the course of experiments to define regulation by intracellular pH (pHi) of the AE2 anion exchanger expressed in Xenopus oocytes, we discovered an unexpected regulation of AE2 by NH4+. Intracellular acidification produced by extracellular acidification or produced by equimolar substitution of NaCl with sodium acetate each inhibited AE2 activity. In contrast, intracellular acidification by equimolar substitution of NaCl with NH4Cl activated AE2-associated, trans-anion-dependent, 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid-sensitive 36Cl- influx and efflux. Regulation by NH4+ was isoform specific, since neither erythroid nor kidney AE1 was activated. AE2 activation was maximal at <5 mM NH4Cl; was not mimicked by extracellular KCl, chloroquine, or polyamines; and was insensitive to amiloride, bumetanide, barium, and gadolinium. Whether NH4Cl acts directly on AE2 or on another target remains to be determined. Activation of AE2 by NH4+ may serve to sustain Cl-/HCO3- exchange activity in the presence of acidic pH in renal medulla, colon, abscesses, and other AE2-expressing acidic locales exposed to elevated NH4+ concentration.

Acids↗

PubMed1997

Acute metabolic acidosis inhibits the induction of osteoblastic egr-1 and type 1 collagen.

Metabolic acidosis induces net calcium efflux from bone through a decrease in osteoblastic formation and an increase in osteoclastic resorption. We tested the hypothesis that changes in external pH would alter the expression of genes critical to the function of mouse calvarial bone cells, predominantly osteoblasts. Cells were cultured in physiologically neutral pH medium until confluent and then stimulated with fresh medium at either neutral or acidic pH. Among a group of immediate early response genes, including egr-1, junB, c-jun, junD, and c-fos, only egr-1 stimulation was modulated by changes in medium pH. At pH 7.4, RNA for egr-1 was stimulated approximately 10- to 30-fold, 40 min after medium change. A progressive decrease in pH to 6.8 led to a parallel reduction in egr-1 stimulation, and an increase in pH to 7.6 led to an increase in egr-1 stimulation. The protein synthesis inhibitor cycloheximide led to a superinduction of egr-1 with preservation of the pH dependency of expression. Osteoblasts synthesize collagen, which is subsequently mineralized. RNA for type 1 collagen was stimulated approximately three- to fivefold, 40 min after medium change. Again the stimulation was inhibited by acidosis and increased by alkalosis. Cycloheximide abolished the pH dependency of expression. These results suggest that small changes in external pH have a significant effect on the expression of certain genes important for osteoblastic function.

Acidosis↗

PubMed1997

Regulation of vascular smooth muscle cell proliferation by plasma membrane Ca(2+)-ATPase.

We have previously shown that reductions in c-Myb-dependent transcription inhibit cell cycle progression and decrease intracellular Ca2+ concentrations in vascular smooth muscle cells (VSMC). We now report that these effects are largely mediated by a 4- to 10-fold increased rate of La(3+)-sensitive 45Ca extrusion, which is associated with 2- to 4-fold increased levels of plasma membrane Ca(2+)-ATPase 1 (PMCA1) mRNA and protein. PMCA4 mRNA, present at much lower concentrations, undergoes similar changes during suppression of c-Myb activity. We also report that PMCA1 expression is regulated during VSMC cell cycle progression, such that levels of PMCA1 are 40% lower at the G1/S interface than at G0. Moreover, transient overexpression of PMCA1a in VSMC elevates the 45Ca efflux rate by approximately 2-fold, decreases resting and peak thapsigargin-releasable Ca2+ concentrations at G1/S by 43% (68 nM) and 52% (160 nM), respectively, and reduces the rate of cell proliferation by over 2.5-fold. These data define a mechanism for c-Myb-dependent Ca2+ homeostasis and support a critical role for PMCA in the regulation of VSMC growth.

Animals↗

PubMed1997

c-Myb-dependent cell cycle progression and Ca2+ storage in cultured vascular smooth muscle cells.

Considerable controversy surrounds the role of the c-myb proto-oncogene in vascular smooth muscle cells (VSMCs). Previous investigations using antisense approaches have suggested a relationship between c-myb expression, cell cycle progression, and cytoplasmic Ca2+ concentration ([Ca2+]cyt). However, the ability of certain antisense oligonucleotides to bind and inactivate growth factors allows alternative explanations. To define more specifically the role of c-Myb in cultured VSMCs (SVE and A10 cell lines), we have generated stable cell clones expressing a dominant-negative c-Myb lacking critical elements of the DNA binding domain (delta5-SVE) and transiently transfected cell populations (GRE-MEn-SVE and GRE-MEn-A10) expressing a glucocorticoid-inducible chimeric protein that targets the Drosophila Engrailed repressor domain to c-Myb-responsive promoters. The delta5-SVE clones and GRE-MEn cell populations exhibit a 60% reduction in mean intracellular c-Myb activity, as measured by cotransfection assays with a c-Myb-responsive reporter, a 42% decrease in the mean S phase entry of growth-arrested (G[0]) cells after serum stimulation, and a 36% inhibition of mean cell proliferation over 4 days. These cells also display 28% (34-nmol/L) and 30% (42-nmol/L) reductions in mean [Ca2+]cyt at G(0) and at the G1/S interface, respectively, as well as significant reductions in the peak [Ca2+]cyt responses to thapsigargin (5 micromol/L) and caffeine (10 mmol/L). These latter reductions in operationally defined Ca2+ pools were observed both at different stages of the cell cycle and after transient induction of the dominant-interfering construct, suggesting that c-Myb regulates these releasable Ca2+ stores independent of its effects on cell cycle progression.

Animals↗

PubMed1997

[Penetration of ciprofloxacin and cefoperazone into human pancreas].

Major pancreatic infection is responsible for more than 80% of deaths in patients with acute pancreatitis. Therefore, the role of antimicrobial drugs in the prevention and treatment of secondary parcreatic infection is very important. The choice of antimicrobial drugs must be based upon the ability of the drug to exceed the therapeutic concentration in pancreas for the common pathogens. The penetration of ciprofloxacin and cefoperazone into pancreas was investigated in ten patients who had undergone pancreatoduodenectomy. The pancreatic juice was temporarily diverted to the exterior via a panoreatic duct catheter. The pancreatic tissue was obtained intraoperatively and pancreatic juice was drained postoperatively. The antimicrobial drug concentrations were determined by high-performance liquid chromatography. The concentrations of ciprofloxacin and cefoperazone in pancreatic juice were 44% and 17%, respectively, of those in serum, and exceeded the in vitro concentration (MIC-90) for most bacteria associated with pancreatic infections. The result indicates that ciprofloxacin and cefoprazone appear to be appropriate for both prophylaxis and therapy of secondary pancreatic infections.

Adult↗

PubMed1997

[Imaging findings of malignant fibrous histiocytoma in the lung].

OBJECTIVE: To show the characteristic findings of the image of primary malignant fibrous histiocytoma (PMFH) in the lung. METHODS: Fifty-one cases of pulmonary PMFH were reviewed, 7 from our hospital and 44 from the literature including chest radiograms 51 cases; CT scans 9 cases and MRI 1 case. RESULTS: Primary MFH comprises 0.01% of all pulmonany malignant tumors seen in the same period. The mean age was 55 years. The most common complaints were cough, hemoptysis and chest pain. In 40 cases who were followed, recurrence/metastasis developed in 42.9% with 80% appearing within one year. The sites of the lesion were: right lobe in 34 cases and left lobe in 17 cases. It was peripheral in 49 (96.1%) cases and central in 2 (3.9%). The finding of the image was a large solitary mass (> 5 cm, 68.6%) with regular or irregular margin. Most of the tumors were well circumscribed (56.9%) or lobulated (43.1%) showing homogeneous attenuation (64.7%). Cystic changes or cavitation was observed in a few cases. On CT, the lesion shows low attenuation and involves the adjacent structures. CONCLUSION: PMFH gives images which are not pathognomonic. Yet, its regular, well defined border, less lobulated configuration could differentiate itself from the common malignant and benign lesionsin the lung. CT and MRI can provide useful information in demonstrating the nature and extent of invasion of the tumor.

Aged↗

PubMed1997

[Determination of chrysophanol in semen Cassiae by HPLC].

A HPLC method for the determination of chrysophanol in Semen Cassiae was investigated. The result showed that this method was simple, specific and accurate. The recovery was 99.0% and relative standard deviation was 1.8%. The method is useful for the quality control of this medicinal meaterial.

Anthraquinones↗

PubMed1997

[The study and manufacture of spinning counter for experimental animals].

The single-chip microcomputer technique is used in the present study of spinning counter, which has 4 observation tunnels, the spinning behave of four experiment animals can be recorded at same time. The function of this instrument has four selections according to different experiment, and the recording data can be compute processed.

Animals↗

PubMed1997

Mutations identified in exon 7 of phenylalanine hydroxylase gene in Chinese.

Exon 7 of the phenylalanine hydroxylase (PAH) gene was analyzed in 45 children affected with classic phenylketonuria (PKU) from northern China by using PCR-single strand conformation polymorphism (PCR-SSCP) technique and DNA direct sequencing. Six missense mutations(i.e. R243Q, R241H, G247V, L249H, F2541 and G257V) and one silent mutation (V245v) were identified. The latter three missense mutations were demonstrated as novel mutations in comparison with the PAH mutation database. One missense mutation (R241H) was first documented in Chinese. Our results showed population and region differences in the PAH mutation distribution, and suggest that there is more than one founding population for PKU in China. The finding of novel mutations will enhence the molecular diagnosis of PKU.

Asian People↗

PubMed1997

[Detection of flaviviruses by reverse-transcription polymerase chain reaction with universal primer set].

For the purpose of early and rapid diagnosis of flavivirus infection, the universal primer set was selected on the NS1 gene. Another five different internal primers were selected on the NS1 genes of DEN1, 2, 3, 4 and JEV. With the universal primer set designed, the NS1 fragment about the size of 413 bp and with the five internal primers, the NS1 fragments about the sizes of 262 bp (DEN1), 189 bp (DEN2), 392 bp (DEN3), 97 bp (DEN4) and 323 bp (JEV) were amplified respectively. The reverse transcription-polymerase chain reaction (RT-PCR) was used to amplify gene fragments of flaviviruses. cDNA of DEN1, 2, 3, 4 and JEV were successfully amplified with universal primer set and internal primers. Sera from 78 patients with dengue fever were assayed by nested PCR, DEN1 was detected from 18 of the 40 patients' sera and DEN2 was detected from 48 patients' sera. Sera from 42 patients with Japanese encephalitis were also assayed by nested PCR, JEV was detected from 35 of the 42 patients' sera. By nested PCR, we completed identification of flaviviruses within 2 days. The results showed that this method has the potential value in rapid clinical diagnosis of flavivirus infection.

DNA Primers↗

PubMed1997

Ceramide is involved in triggering of cardiomyocyte apoptosis induced by ischemia and reperfusion.

Involvement of ceramide signaling in the initiation of apoptosis induction in myocardial cells by in vitro and in vivo ischemia and reperfusion was analyzed. Synthetic cell permeable C2-ceramide induced apoptotic death of rat neonatal cardiomyocytes in vitro. In vitro ischemia (oxygen/serum/glucose deprivation) led to a progressive accumulation of ceramide in cardiomyocytes. After 16 hours of simulated in vitro reperfusion (readdition of oxygen, serum and glucose), the level of ceramide in surviving cells was found to have returned to baseline, whereas, levels in nonadherent dead cells remained high. In the rat heart left coronary artery occlusion model, ischemia with the subsequent reperfusion, but not ischemia alone, induced apoptosis in myocardial cells as demonstrated by DNA electrophoresis and measurement of soluble chromatin degradation products. The content of ceramide in ischemic area was elevated to 155% baseline levels at 30 minutes, and to 330% after 210 minutes of ischemia. Ischemia (30 minutes) followed by reperfusion (180 minutes) increased the ceramide level to 250% in the ischemic area. The combination of results obtained in both in vitro and animal models demonstrate for the first time that ceramide signaling can be involved in ischemia/reperfusion death of myocardial cells.

Animals↗

PubMed1997

[Novel mutations identified in exon 7 of phenylalanine hydroxylase gene in Chinese].

Exon 7 of the phenylalanine hydroxylase (PAH) gene was analyzed in 45 children affected with classic phenylketonuria (PKU) from northern China by using PCR-single strand conformation polymorphism (PCR-SSCP) technique and DNA direct sequencing. Six missense mutations (i.e. R243Q, R241H, G247V, L249H, P254I and G257V) and one silent mutation (V245V) were identified. The latter three missense mutations were demonstrated as novel mutations in comparison with the PAH mutation Database. One missense mutation (R241H) was first documented in Chinese. Our results showed population and regional differences in the PAH mutation distribution and suggest that there is more than one founding population for PKU in China. The finding of novel mutations will enhance our capability in molecular diagnosis of PKU.

Child↗

PubMed1997

[The inhibition effect of foreign retinoblastoma gene mediated by recombinant adenovirus vector on the growth of smooth muscle cells].

OBJECTIVE: To study the effect of foreign retinoblastoma (Rb) gene mediated by recombinant adenovirus vector on vascular smooth muscle cell (SMC) and the possibility by using Rb gene for gene therapy of atherosclerosis and artery restenosis. METHODS: Rb gene recombinant adenovirus vector was constructed to transfect into rabbits' aortic SMC in vitro. The efficiency of transfection and expression was detected by biochemical staining, immunocytochemical analysis and polymerase chain reaction technique. The role of Rb gene for SMC proliferation, DNA synthesis and cell cycle were observed by cell counting. 3H-incorporation and cytometer respectively. RESULTS: Adenovirus vector transfered the Rb gene into SMC effectively. The expression of Rb gene restricted the proliferation of SMC, decreased the DNA synthesis and plaaied a role in the cell cycle. CONCLUSION: Rb gene mediated by adenovirus can be used to treat atherosclerosis.

Adenoviruses, Human↗