Biomedical subjects

D Jiang

Publications and source records attributed to D Jiang.

At least 73 records · Page 4Linked to original sources

PubMed1999

Molecular cloning and sequencing of two 'short chain' and two 'long chain' K(+) channel-blocking peptides from the Chinese scorpion Buthus martensii Karsch.

Five full-length cDNAs encoding the precursors of two 'short chain' scorpion non-toxic peptides active on Ca(2+)-activated K(+) channels (BmP02 and BmP03) and two novel putative long chain K(+) channel-blocking peptides (named BmTXKbeta and BmTXKbeta2) were first isolated from the venom gland cDNA library of the Chinese scorpion Buthus martensii Karsch (BmK). BmTXKbeta2 showed a high similarity with AaTXKbeta, while BmTXKbeta was completely different in the deduced primary structure from the long chain and short chain scorpion toxins already characterized. Thus, BmTXKbeta expands the scorpion long chain K(+) channel-blocking peptide family. Although little sequence similarity exists between the above two short and two long peptides, they are similar at the positions of six cysteines, suggesting that they should all share a similar scaffold composed of an alpha-helix and a three-stranded beta-sheet.

3' Untranslated Regions↗

PubMed1999

Existence and global attractivity of positive periodic solutions of periodic n-species Lotka-Volterra competition systems with several deviating arguments.

In this paper, we study the existence and global attractivity of positive periodic solutions of periodic n-species Lotka-Volterra competition systems. By using the method of coincidence degree and Lyapunov functional, a set of easily verifiable sufficient conditions are derived for the existence of at least one strictly positive (componentwise) periodic solution of periodic n-species Lotka-Volterra competition systems with several deviating arguments and the existence of a unique globally asymptotically stable periodic solution with strictly positive components of periodic n-species Lotka-Volterra competition system with several delays. Some new results are obtained. As an application, we also examine some special cases of the system we considered, which have been studied extensively in the literature. Some known results are improved and generalized.

Animals↗

PubMed1999

A novel aminosteroid is active for proliferation inhibition and differentiation induction of human acute myeloid leukemia HL-60 cells.

A novel aminosteroid, 2beta-(4'-methyl-1'piperazinyl)-3alpha,17beta-dihydroxyl+ ++-5alpha-androstane (HY), was found to inhibit proliferation of HL-60 leukemia cells and induce these cells to differentiate toward macrophage-like cells from the following evidence. (1) It inhibited HL-60 cell proliferation by cell counts, colony counts and MTT assay; (2) It caused morphological changes toward macrophage-like cells after culture for 6 days; (3) It induced NBT reduction activity; (4) It induced alpha-naphthyl acetate esterase activity and (5) it induced CD11b and CD14 expression indicated by flow cytometry analysis. There is potential for this novel aminosteroid in the treatment of myeloid leukemia.

Androstane-3,17-diol↗

PubMed1999

Electron transfer between ferrocene-modified Au/octadecanethiol/lipid BLM electrode and redox couples in solution.

Bilayers incorporated with ferrocene consisting of self-assembled octadecanethiol and lipid monolayer on gold substrates were fabricated. Its electrochemical behaviors in solutions containing different redox couples were investigated by cyclic voltammetry and ac impedance. The transmembrane electron transfer reaction across octadecanethiol self-assembled film and an adsorbed phospholipid layer mediated by ferrocene have been observed in the solution of Fe(CN)6(3-/4-). The formal potential difference between mediator in bilayer lipid membrane (BLM) and redox couple in solution has a great impact on the transmembrane electron transfer behavior. The ferrocene-modified BLM electrodes might be useful for constructing a bilayer-based electrochemical current rectifying device.

Algorithms↗

PubMed1999

Unmodified supported thiol/lipid bilayers: studies of structural disorder and conducting mechanism by cyclic voltammetry and AC impedance.

Supported thiol/lipid bilayer assembly, one of the most spectacular bilayer systems in recent years, has provided a good model to study biomembranes because of its high mechanical stability. In this work, the structural and conducting property of unmodified Au supported octadecanethiol/phosphatidylcholine bilayers were investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The forming process of bilayer was monitored by capacitance plane plot. The normalized membrane capacitance of supported bilayer is 0.52 microF cm(-2). Kinetically controlled voltammograms determined by Butler-Volmer equation were obtained for both thiol monolayer and thiol/lipid bilayer in linear sweep voltammetry. Results of EIS experiment indicate that collapsed sites and pinhole defects exist in thiol monolayer and lipid monolayer, respectively. The difference between the values of experimental and theoretical standard electron transfer rate constant indicates that the conducting mechanism of Au supported thiol monolayer is electron tunneling at collapsed sites. The conducting mechanism of Au supported thiol/lipid bilayer is attributed as the following: the electroactive species could diffuse through pinholes in the lipid monolayer and reach collapsed sites in thiol monolayer, where electron transfer occurs via a tunneling process. The fractional coverage of the lipid monolayer measure by EIS experiments is about 0.98 or higher.

Electrochemistry↗

PubMed1999

Interactions of the novel antipsychotic aripiprazole (OPC-14597) with dopamine and serotonin receptor subtypes.

OPC-14597 {aripiprazole; 7-(-4(4-(2,3-dichlorophenyl)-1-piperazinyl) butyloxy)-3,4-dihydro-2(1H)-quinolinone} is a novel candidate antipsychotic that has high affinity for striatal dopamine D2-like receptors, but causes few extrapyramidal effects. These studies characterized the molecular pharmacology of OPC-14597, DM-1451 (its major rodent metabolite), and the related quinolinone derivative OPC-4392 at each of the cloned dopamine receptors, and at serotonin 5HT6 and 5HT7 receptors. All three compounds exhibited highest affinity for D2L and D2S receptors relative to the other cloned receptors examined. Both OPC-4392 and OPC-14597 demonstrated dual agonist/antagonist actions at D2L receptors, although the metabolite DM-1451 behaved as a pure antagonist. These data suggest that clinical atypicality can occur with drugs that exhibit selectivity for D2L/D2S rather than D3 or D4 receptors, and raise the possibility that the unusual profile of OPC-14597 in vivo (presynaptic agonist and postsynaptic antagonist) may reflect different functional consequences of this compound interacting with a single dopamine receptor subtype (D2) in distinct cellular locales.

Animals↗

PubMed1999

Caspases in T-cell receptor-induced thymocyte apoptosis.

Apoptosis eliminates inappropriate or autoreactive T lymphocytes during thymic development. Intracellular mediators involved in T-cell receptor (TCR)-mediated apoptosis in developing thymocytes during negative selection are therefore of great interest. Caspases, cysteine proteases that mediate mature T-cell apoptosis, have been implicated in thymocyte cell death, but their regulation is not understood. We examined caspase activities in distinct thymocyte subpopulations that represent different stages of T-cell development. We found caspase activity in CD4+CD8+ double positive (DP) thymocytes, where selection involving apoptosis occurs. Earlier and later thymocyte stages exhibited no caspase activity. Only certain caspases, such as caspase-3 and caspase-8-like proteases, but not caspase-1, are active in DP thymocytes in vivo and can be activated when DP thymocytes are induced to undergo apoptosis in vitro by TCR-crosslinking. Thus, specific caspases appear to be developmentally regulated in thymocytes.

Animals↗

PubMed1999

Desynchronizing responses to correlated noise: A mechanism for binaural masking level differences at the inferior colliculus.

We examined the adequacy of decorrelation of the responses to dichotic noise as an explanation for the binaural masking level difference (BMLD). The responses of 48 low-frequency neurons in the inferior colliculus of anesthetized guinea pigs were recorded to binaurally presented noise with various degrees of interaural correlation and to interaurally correlated noise in the presence of 500-Hz tones in either zero or pi interaural phase. In response to fully correlated noise, neurons' responses were modulated with interaural delay, showing quasiperiodic noise delay functions (NDFs) with a central peak and side peaks, separated by intervals roughly equivalent to the period of the neuron's best frequency. For noise with zero interaural correlation (independent noises presented to each ear), neurons were insensitive to the interaural delay. Their NDFs were unmodulated, with the majority showing a level of activity approximately equal to the mean of the peaks and troughs of the NDF obtained with fully correlated noise. Partial decorrelation of the noise resulted in NDFs that were, in general, intermediate between the fully correlated and fully decorrelated noise. Presenting 500-Hz tones simultaneously with fully correlated noise also had the effect of demodulating the NDFs. In the case of tones with zero interaural phase, this demodulation appeared to be a saturation process, raising the discharge at all noise delays to that at the largest peak in the NDF. In the majority of neurons, presenting the tones in pi phase had a similar effect on the NDFs to decorrelating the noise; the response was demodulated toward the mean of the peaks and troughs of the NDF. Thus the effect of added tones on the responses of delay-sensitive inferior colliculus neurons to noise could be accounted for by a desynchronizing effect. This result is entirely consistent with cross-correlation models of the BMLD. However, in some neurons, the effects of an added tone on the NDF appeared more extreme than the effect of decorrelating the noise, suggesting the possibility of additional inhibitory influences.

Acoustic Stimulation↗

PubMed1999

Anorganic bovine bone supports osteoblastic cell attachment and proliferation.

BACKGROUND: It was the aim of these studies to examine the ability of an anorganic bovine bone matrix material as an alternative to autogenous bone grafts and demineralized cadaver bone to support the attachment, spreading, and proliferation of isolated osteoblastic cells. METHODS: Primary culture osteoblastic cells were isolated from neonatal rat calvaria by sequential collagenase digestion. In the attachment studies, cells which had been labeled with 3H-leucine were incubated with the matrix material in sterile microfuge tubes for 15, 90, or 180 minutes or 24 hours. The attached cells were released and the radioactivity measured by liquid scintillation spectrometry. In the proliferation experiments, the cells were cultured with the matrix material for 24 hours and 3H-thymidine was added during the last 2 hours of the incubation. The cells were released and the radioactivity measured by liquid scintillation spectrometry. Scanning electron microscopy (SEM) was employed to observe osteoblastic cell interaction with the anorganic bone matrix. In these studies the cells were seeded on the bone graft material, then the material was removed and processed for SEM after 30, 60 or 120 minutes, or 24 or 48 hours. RESULTS: The cells attached to the matrix material in a time-dependent manner. There were significantly (P<0.05) more cells attached after 180 minutes than after the 15 and 90 minute incubations. The matrix material also supported proliferation of the attached osteoblastic cells. Cells seeded onto 100 mg of anorganic bovine bone resulted in significantly (P<0.05) more measurable proliferation than cells seeded onto 10 mg of material. The cells appeared to be round as they attached, then flatten and spread over time. There was also evidence of cellular processes extending into the pores of the material. CONCLUSIONS: These results demonstrate that this anorganic bovine bone graft material is able to support the attachment and proliferation of osteoblastic cells.

Animals↗

PubMed1999

Modification of an osteoconductive anorganic bovine bone mineral matrix with growth factors.

BACKGROUND: Osteoconductive anorganic bovine bone mineral matrix material has been used clinically in bone regeneration procedures. Platelet-derived growth factor-BB (PDGF-BB) and insulin-like growth factor (IGF-I) are important anabolic growth factors for bone. It was the aim of these studies to 1) examine the interaction of this bone graft material with PDGF-BB and IGF-I and 2) determine if the combination of growth factors with the matrix could stimulate osteoblastic cell proliferation. METHODS: Adsorption of PDGF-BB and IGF-I was done using 125I radio-labeled growth factors. The PDGF-BB or IGF-I was incubated with the anorganic bovine bone matrix, and the amount of adsorbed growth factor was measured. In the desorption studies, radiolabeled growth factors were adsorbed to the matrix material. The samples were incubated in buffer for various time periods, and the amount remaining on the matrix was measured to calculate the percentage of released growth factor. The biological activity was tested in an in vitro assay with primary culture neonatal rat osteoblastic cells. Porous bone matrix with known amounts of adsorbed PDGF-BB or IGF-I was produced. The osteoblastic cells were cultured on the bone mineral matrix, with and without adsorbed growth factor, and proliferation was assessed by 3H-thymidine incorporation. RESULTS: Both PDGF-BB and IGF-I adsorbed to bone mineral matrix in a concentration-dependent fashion. The affinity of IGF-I for the material was 10-fold greater than PDGF-BB. In the experiments that measured the release of the initially adsorbed growth factors, approximately 50% of the PDGF-BB and 10% of the IGF-I were released after 10 days. PDGF-BB adsorbed to the matrix material significantly (P <0.05, ANOVA) enhanced the proliferation of cultured osteoblastic cells compared to the mineralized matrix alone. However, IGF-I adsorbed to the matrix material did not significantly enhance cell proliferation. CONCLUSIONS: These results suggest that PDGF-BB can be adsorbed to the anorganic bovine bone mineral matrix and that this growth factor subsequently enhances the osteogenic properties of this bone graft material. IGF-I also adsorbed to the graft material; however, it was not readily released and it did not produce significant effects in the biologic assay. It appears that it may be clinically feasible to adsorb PDGF to anorganic bovine bone and that this combination of bone growth factor and mineral matrix has the potential for clinical applications.

Adsorption↗

PubMed1999

[The relationship between polymorphism of LMP2 and LMP7 genes and the phenotype of ankylosing spondylitis].

OBJECTIVE: To evaluate the relationship of the polymorphism of LMP2 and LMP7 genes and the phenotype of patients with ankylosing spondylitis(AS). METHODS: One hundred and eighteen blood samples were collected from patients with AS and acute anterior uveitis(AAU). HLA-B(27) typing was performed and LMP2 and LMP7 amplified fragment length polymorphisms were determined after PCR and digestion with Cfo I restriction enzyme in the study. RESULTS: There was a significantly increased LMP2 BB genotype frequency in patients with AS+AAU(86.9%) and AAU(87%), compared with controls(53.3%) and AS patients(63.1%)(P<0.05); the odds ratio(OR) relating LMP2 BB and AAU was 5.83, and the OR for AS+AAU was 3.71. No difference was found between adult AS and junior AS and between AS patients with and without extraspinal arthritis. No difference was found in LMP7 genotype. CONCLUSION: The polymorphism of LMP2 gene is strongly associated with the development of AAU in AS patients and in uncomplicated AAU patients, but not with the age at onset and the type of joints affected.

Adolescent↗

PubMed1999

Regulation of D(1) dopamine receptors with mutations of protein kinase phosphorylation sites: attenuation of the rate of agonist-induced desensitization.

Investigations of D(1) receptor regulation have suggested a role for cAMP-dependent protein kinase (PKA) in agonist-induced desensitization and down-regulation of receptor expression. Given the presence of at least four possible consensus recognition sites for PKA on the D(1) receptor protein, a reasonable hypothesis is that some of these PKA-mediated effects are caused by phosphorylation of the receptor. As an initial test of this hypothesis, we used site-directed mutagenesis to create a mutant D(1) receptor with substitutions at each of its four potential PKA phosphorylation sites. The modified amino acids are as follows: Thr135 to Val, Ser229 to Ala, Thr268 to Val, and Ser380 to Ala. Characterization of the wild-type and mutant receptors stably expressed in C6 glioma cells suggests that the mutations have no effect on receptor expression, antagonist or agonist affinities, or on functional coupling with respect to cAMP generation. Similarly, dopamine preincubation of the stably transfected C6 cells expressing either the wild-type or mutated D(1) receptors results in an agonist-induced loss of ligand binding activity (down-regulation) in an identical fashion. In contrast, the time of onset of dopamine-induced desensitization is greatly attenuated in the quadruple mutant receptor. After 1 h of dopamine pretreatment, the wild-type receptor exhibits approximately 80% desensitization of the cAMP response, whereas the mutant receptor is desensitized by only approximately 20%. Further analyses of single mutated receptors, in which only one of the four putative phosphorylation sites is modified, reveals that Thr268 in the third cytoplasmic loop of the receptor protein is primarily responsible for regulating the desensitization kinetics. These results are consistent with the hypothesis that phosphorylation of the D(1) receptor on Thr268 is important for rapid agonist-induced homologous desensitization.

Amino Acid Sequence↗

PubMed1999

Effect of lithium on growth of bone marrow stromal cells.

OBJECTIVE: To investigate the effect of lithium on the growth of bone marrow stromal cells. METHODS: We compared the different effects of lithium with the concentration of 0.1-12 mmol/L on the growth of murine fibroblast colony forming unit (mCFU-F), human fibroblast colony forming unit (hCFU-F) and their intercolonial cells. Pure murine bone marrow stromal cell assay was used to investigate the mechanism. RESULTS: Cultures with 1-4 mmol/L lithium resulted in significant increase in the number of hCFU-F, but distinct decrease in the number of mCFU-F. Furthermore, there were much more endothelial cells between mCFU-Fs than those between hCFU-Fs. The direct effect of 1-4 mmol/L lithium on the growth of pure murine fibroblasts and endothelial cells was stimulatory. Serum-free endothelial cell conditioned medium (EC-CM) could inhibit the growth of mCFU-F. CONCLUSIONS: 1-4 mmol/L lithium has stimulatory effect on the growth of pure murine fibroblasts and endothelial cells. The inhibitory effect of lithium on mCFU-F formation may result from the effect of increased endothelial cells.

Animals↗

PubMed1999

Ben cao tu jing (Illustrated Canon of Herbology) and the origin of modern identification of Chinese materia medica.

There is certain relation between the development of modern identification of Chinese materia medica and Ben cao tu jing. The purpose of Su Song's compilation of this book and the tasks of modern identification of Chinese materia medica, including the verification of genuineness, superiority of the drugs to ensure their qualities, are quite similar, and quite close in their contents. Suffice it to say that Ben cao tu jing made considerable contribution to modern identification of Chinese drugs, with a role of linking the past with the present.

Chin↗

PubMed1999

[Evidence of increased endogenous carbon monoxide production in asthma].

OBJECTIVE: To investigate the role of carbon monoxide (CO) in the pathogenesis of asthma. METHODS: We examined CO, nitrite and nitrate (NO2[not readable: see text]/NO3[not readable: see text]) and tumor necrosis factor alpha (TNF-alpha) levels in plasma of 26 asthmatic children and 22 matched normal children. At the same time, we examined the plasma and bronchoalveolar lavage fluid (BALF) CO, NO2[not readable: see text]/NO3[not readable: see text] and TNF-alpha levels in guinea-pigs with allergic asthma. RESULTS: Asthmatic children in acute attack stage had increased levels of CO, NO2[not readable: see text]/NO3[not readable: see text] and TNF-alpha in plasma compared with normal control subjects (all P < 0.01), while in stable stage plasma CO and NO2[not readable: see text]/NO3[not readable: see text] reduced to normal levels (both of the P > 0.05), but TNF-alpha was still higher than the normal controls (P < 0.01). Guinea-pigs with allergic asthma had increased amounts of CO and TNF-alpha in plasma and CO, NO2[not readable: see text]/NO3[not readable: see text] and TNF-alpha in BALF as compared with normal control subjects (P < 0.05-0.01), but no changes in levels of circulating NO2[not readable: see text]/NO3[not readable: see text] (P > 0.05) were found. There was no difference between glucocorticoid treated asthmatic guinea pigs and normal controls in levels of CO, NO2[not readable: see text]/NO3[not readable: see text], and TNF-alpha. The elevation of plasma CO correlated with elevated NO2[not readable: see text]/NO3[not readable: see text] level in asthmatic children (P < 0.05), so did in the BALF in allergic guinea-pigs. CONCLUSIONS: Our present data showed that endogenously produced CO was increased during the course of asthma, which suggested that the role of CO in asthma might worth further study.

Animals↗

PubMed1999

[Observations on expression of c-fos and c-myc genes and activity of PDGFBB autocrine loop in 67 human gliomas].

OBJECTIVE: To investigate the variance of expression of c-fos and c-myc genes and the activity of platelet-derived growth factor (PDGF) BB autocrine loop in human gliomas as well as their relationship. METHODS: In situ hybridization and immunohistochemistry were used to study 67 human glioma specimens of different grades. RESULTS: The incidences, of positive expression for c-fos mRNA, c-fos protein, c-myc mRNA and c-myc protein were 100% (67/67), 100% (67/67), 85.1% (57/67) and 83.6% (56/67) respectively. There was significant positive correlation between the positive cell densities of c-fos mRNA (92.49 +/- 33.87) and c-fos protein (91.64 +/- 38.11), and of c-myc mRNA (72.70 +/- 40.56) and c-myc protein (71.49 +/- 41.11, r = 0.917 - 0.988, P < 0.001). All of them also increased correspondingly with the malignant degree of the tumors and level of PDGFB mRNA expression in the tumor cells (P < 0.05 - 0.01). Not only were the positive cell densities of PDGF alpha receptor (58.46 +/- 28.77), PDGF beta receptor (63.03 +/- 31.63) and phosphotyrosine protein (68.25 +/- 29.30) correlated positively with one another (r = 0.827 - 0.896, P < 0.001), but they also all correlated positively with the positive cell densities of PDGFB mRNA, c-fos mRNA, c-fos protein, c-myc mRNA and c-myc protein respectively (r = 0.615 - 0.888, P < 0.001). CONCLUSIONS: The abnormally increased activity of the PDGFBB autocrine loop possibly upregulated the overexpression of c-fos and c-myc genes in glioma cells and suggested that c-fos and c-myc proteins probably played an important role as downstream response factors in the signaling pathway in which PDGFBB could induce gliocyte transformation and glioma development.

Adolescent↗

PubMed1999

[Immunogenicity of retina in mice].

OBJECTIVE: To evaluate the immunogenicity of retina. METHODS: DBA/2 mice (MHCH-2d) were used as donors, C57BL/6 mice (MHC H-2d) or BALB/C mice (MHC H-2d) as recipients. Half retina of DBA/2 mouse was transplanted subcutaneously to a C57BL/6 or BALB/C mouse. The delayed-type hypersensitivity (DTH) and specific killing rate of cytotoxic T lymphocyte(CTL) were detected two weeks later. RESULTS: The results of DTH and specific killing rate of CTL in the retina of DBA/2 mice were significantly lower than the positive group(P < 0.01), but significantly higher than the negative group(P < 0.01). CONCLUSION: MHC Class I and Class II antigen and minor histocompatibility complex antigen(Minor HC) are expressed in the retina of the DBA/2 mouse, which stimulates immune system of recipient to produce weak cellular immune response. It is suggested that the retina has weak immunogenicity.

Animals↗

PubMed1999

[Effects of cytokines and umbilical cord blood preserved at 4 degrees C on the growth of CFU-GM and HPP-CFC].

We studied the effects of different cytokine combinations and umbilical cord blood preserved at 4 degrees C for 4 days on the growth of CFU-GM and HPP-CFC. The results showed that the growth of umbilical cord blood CFU-GM was markedly different when various combinations of cytokines were used. After 2 weeks culturing with IL-3 alone or plus GM-CSF, the number of umbilical cord blood CFU-GM was increased when compared with GM-CSF group; upon stimulation with GM-CSF plus IL-3 plus IL-6 plus Epo, a significant increase of umbilical cord blood CFU-GM was seen. After umbilical cord blood being preserved 4 days at 4 degrees C, the number of umbilical cord blood CFU-GM and HPP-CFC was decreased.

Blood Preservation↗