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Biomedical subjects

J Du

Publications and source records attributed to J Du.

At least 145 records · Page 8Linked to original sources
PubMed1999

Optimization of L-lactic acid production from glucose by Rhizopus oryzae ATCC 52311.

The effect of nutrients on L(+)-lactic acid production from glucose was investigated using Rhizopus oryzae ATCC 52311. From the shake-flask experiments, the optimal medium composition was defined for improved lactic-acid production. In order to enhance lactic-acid production rate and product yield, controlled aeration in a bubble column was conducted under optimal conditions. Results showed a maximum lactic-acid production rate of 2.58 g/L/h was obtained with an initial glucose concentration of 94 g/L. Final lactic-acid concentration of 83 g/L was achieved after 32 h of fermentation with a weight of 0.88 g lactic acid/g glucose consumed.

Journal Article↗
PubMed1999

[Inhibitory effect of IGF-II antisense RNA on malignant phenotype of hepatocellular carcinoma].

OBJECTIVE: Inhibitory effect of insulin like growth factor II (IGF-II) antisense RNA on malignant phenotype of hepatic cancer cells was studied. METHODS: A 0.1 kb cDNA of human IGF-II was reversely inserted into a eukaryotic expression vector of pcDNA3 and an IGF-II antisense RNA expression vector of pIGF-II As was obtained. The pIGF-II As was then introduced into human hepatic cancer cell line SMMC-7721. The effect of IGF-II antisense RNA which was expressed by pIGF-II As on SMMC-7721 cell cycles progression was measured with FCM. RESULTS: The coloning formation in anchorage-independent assay of SMMC-7721 cells with pIGF-II As was significantly decreased by comparison with control groups of SMMC-7721 cells and SMMC-7721 cells transfected with pcDNA3 vector alone. FCM analysis showed that the S phase of cell cycles for SMMC-7721 cells with pIGF-II As was increased, but there were no obvious changes in the control groups of SMMC-7721 cells and SMMC-7721 cells with pcDNA3. CONCLUSION: The pIGF-II As of IGF-II antisense RNA acts as an inhibitor on carcinogenesis of the SMMC-7721 cells in vitro.

Animals↗
PubMed1999

Oxytocin does not induce a rise in intracellular free calcium in human breast cancer cells.

Research suggests that oxytocin acts as a growth modulating agent for breast cancer cells. However, the signaling mechanisms responsible for these modulatory effects have not been fully elucidated. In the physiological setting oxytocin is known to stimulate contraction of myometrial cells in the uterus and myoepithelial cells in the breast by increasing intracellular free calcium ([Ca2+]i). The expression of oxytocin receptor mRNA in T-47D breast cancer cells, and four additional breast cancer cell lines (BT-549, MCF-7, MDA-MB- 231, ZR-75-1), was confirmed by RT-PCR analysis. Oxytocin-induced changes in [Ca2+]i in indo-1 AM loaded T-47D breast cancer cells were monitored using flow cytometric analysis. In this cell line, oxytocin (0, 1, 10, 100, and 1,000 nM) did not induce a dose-dependent increase in the mean 405 nm/485 nm emission ratio. These results indicate that oxytocin signaling in T-47D breast cancer cells does not appear to involve an increase in [Ca2+]i.

Base Sequence↗
PubMed1999

Ion exchange tumor targeting: a new approach.

Connective tissues are distinguished by the types, concentrations, and organizations of material in the extracellular matrix. Many physiological functions are determined largely by the nature and organization of the extracellular components. The components are characterized by their content and distribution of charged, mostly anionic groups. The distinct roles played by the charges are sometimes modeled by analogy to the transport theory of ion exchange resins. The intent of this study was to investigate whether the properties of the tumor matrix could be used for selective, charge-dependent accumulation of charge-modified dextran. Ten patients with diagnosed superficial urinary bladder carcinoma were included in the study. They received intravesical instillations of technetium-99m-labeled charge-modified dextran derivatives (approximately 0.1-1 mg; approximately 50 MBq in saline; 30-min incubation). After treatment and resection, samples were taken from normal and diseased tissue. The result clearly demonstrated a charge-dependent difference in the quotient of radioactive uptake in tumor tissue: normal tissue. Instillations of cationic dextran yielded a high quotient, up to 3000. Normal tissue had background activity. Anionic dextran yielded a low quotient, 1.8-2, with increased background (i.e. uptake in normal tissue). Neutral dextran gave a quotient of up to 90. No radioactivity could be detected in blood. The tumors in this study apparently displayed cation-exchanging properties. We will continue this investigation and determine whether this is a general property of bladder carcinomas and whether other carcinomas display ion exchange properties. If this is the case, the finding could have important implications for the local treatment of several cancers.

Dextrans↗
PubMed1999

[Clinical analysis of the absent and/or reverse end diastolic velocity of fetal umbilical artery].

OBJECTIVE: To investigate the relations between absent and/or reverse end diastolic velocity of fetal umbilical artery (AEDV) and maternal and fetal pathological factors and perinatal outcome. METHODS: To analyze the clinical informations of 33 case, with AEDV by pulse doppler ultrasonic examination. RESULTS: (1) There are 9 cases (27.3%) complicated with different kinds of fetal morphologic abnormality, 6 cases of perinatal death. (2) In 6 cases (18.2%) of twins, twin-twin transfusion syndrome (TTTS) occurred in 3 cases. In 6 cases when the body weight differences between the 2 babies were higher than 24.8%, neonatal death occurred in 4 cases. (3) The group with AEDV showed significantly higher incidence of pregnancy induced hypertension, oligoaminos, IUGR, fetal distress and neonatal death than that of normal group. CONCLUSIONS: The appearance of AEDV shows the extreme disfunction of mothermal placental-fetal circulation and may be related to poor outcome.

Blood Flow Velocity↗
PubMed1999

Evaluation of cardiac beta-adrenergic receptor function in children by dobutamine stress echocardiography.

OBJECTIVE: To investigate the role of dobutamine stress echocardiography in evaluating cardiac beta-adrenergic receptor (beta-AR) function and responsiveness in children. METHODS: Left ventricular ejection fraction (EF), fractional shortening (FS), left ventricular end systolic volume index (ESVI), the ratio of systolic blood pressure and ESVI (SP/ESVI) were measured by dobutamine stress echocardiography (DSE) in 30 children with beta-AR hypersensitivity, 15 children with dilated cardiomyopathy and 30 normal children respectively. RESULTS: Before pharmacological stress, EF and FS were 0.72 and 0.39 respectively in beta-AR hypersensitivity group versus 0.70 and 0.35 respectively in control group. There was no difference of the indices between the two groups (P > 0.05). SP/ESVI was 0.76, higher than the value of 0.66 in control group (P < 0.05); EF, FS and SP/ESVI were 0.41, 0.15 and 0.10 respectively, which were significantly lower than those in control group. After dobutamine stress of 5 micrograms.kg-1.min-1 and 10 micrograms.kg-1.min-1, EF, FS and SP/ESVI were significantly increased in patients with beta-AR hypersensitivity and there were no changes in children with dilated cardiomyopathy compared with values of baseline. CONCLUSION: Cardiac beta-AR function and responsiveness can be evaluated by dobutamine stress echocardiography.

Adolescent↗
PubMed1999

[The role of hysterectomy in the therapy of gestational trophoblastic tumor].

OBJECTIVE: To evaluate the role of hysterectomy for patients with gestational trophoblastic tumor. METHODS: A total of 68 cases of gestational trophoblastic neoplasia treated by hysterectomy from 1985-1997 at PUMC hospital was retrospectively analyzed. Thirty-eight cases were diagnosed as choriocarcinoma and 30 as invasive mole. RESULTS: Twenty-three elder patients who didn't desire to preserve fertility were selected for hysterectomy after short courses of chemotherapy. Twenty-two of them had complete remission (95.6%). The average total course of chemotherapy was 4.2. Of twenty-seven chemo-refractory cases who were suspected of an isolated lesion in the uterus, delayed hysterectomy as an adjunct to chemotherapy was performed. Twenty of them achieved complete remission (74.1%), with an average 9.4 courses of chemotherapy. Emergency hysterectomy was indicated in 18 patients with uterine perforation or life-threatening hemorrhage. Seventeen of the emergent cases had complete remission (94.4%), who had received an average 7.6 courses of chemotherapy. CONCLUSION: Although the development of effective chemotherapy has resulted in improved survival of patients with gestational trophoblastic tumor, hysterectomy remains an important adjunct treatment in a selected subset of patients. Modified radical hysterectomy is recommended for the indicated patients.

Female↗
PubMed1999

[Biocompatibility of self-designed absorbable hydroxyapatite/poly (DL-lactide) composites].

The biocompatibility of self-designed hydroxyapatite/poly (DL-lactide) rods was evaluated both in vitro and in vivo including Ames test, micronucleus test, acute and subacute systemic toxicity test, hemolysis test, hemopexis test and long-term muscle and bone implant test. The results indicate that the material has no toxicity, no stimulation and mutation, and it does not cause hemolysis and hemopexis. Consequently, the biocompatibility of the composite was good.

Absorbable Implants↗
PubMed1999

[A comparative study of three-dimensional movements of lumbar spine in the old and the young people].

This article is aimed at the differences in lumbar vertebral three-dimensional movement and in stability between the old and the young people, and at the reasons which lead to the differences. Fifteen fresh adult male cadavers were divided into two groups: the young group, 20-30 years old, comprising 7 cases; the old group, 60-70 years old, 8 caes. Lumbar spine(L1-S1) was cut down. Three-dimensional movements under a loading system were measured by a compute system. The result showed that the range of the motion of the old group was lower than that of the young group. It suggests that the lumbar spine of the old people is more stable than that of the young people. This may be associated with the degeneration of the lumbar vertebra, which arouses biocompensatory changes, so the lumbar spine becomes re-stable.

Adult↗
PubMed1998

cAMP-response-element-binding-protein-binding protein (CBP) and p300 are transcriptional co-activators of early growth response factor-1 (Egr-1).

Egr-1 (early-growth response factor-1) is a sequence-specific transcription factor that plays a regulatory role in the expression of many genes important for cell growth, development and the pathogenesis of disease. The transcriptional co-activators CBP (cAMP-response-element-binding-protein-binding protein) and p300 interact with sequence-specific transcription factors as well as components of the basal transcription machinery to facilitate RNA polymerase II recruitment and transcriptional initiation. Here we demonstrate a unique way in which Egr-1 physically and functionally interacts with CBP/p300 to modulate gene transcription. CBP/p300 potentiated Egr-1 mediated expression of 5-lipoxygenase (5-LO) promoter-reporter constructs, and the degree of trans-activation was proportional to the number of Egr-1 consensus binding sites present in wild-type and naturally occurring mutants of the 5-LO promoter. The N- and C-terminal domains of CBP interact with the transcriptional activation domain of Egr-1, as demonstrated by a mammalian two-hybrid assay. Direct protein-protein interactions between CBP/p300 and Egr-1 were demonstrated by glutathione S-transferase fusion-protein binding and co-immunoprecipitation/Western-blot studies. These data suggest that CBP and p300 act as transcriptional co-activators for Egr-1-mediated gene expression and that variations between individuals in such co-activation could serve as a genetic basis for variability in gene expression.

Animals↗
PubMed1998

Kinetic studies on the effect of yeast cofilin on yeast actin polymerization.

The effect of yeast cofilin on the kinetics of polymerization of yeast actin has been examined at 20 degrees C at both pH 8.0 and 6.6. In the absence of cofilin, the kinetic data may be described by a simple nucleation-elongation mechanism. Kinetic data in the presence of cofilin suggests a complex dependence on the cofilin concentration. At low cofilin-to-actin ratios, cofilin increases the rate of polymerization in a way best fit by assuming filament fragmentation. The apparent fragmentation rate constants increase with increasing cofilin concentration leveling off above a cofilin-to-actin ratio of 1:8 and are independent of pH. At higher cofilin-to-actin ratios, a nonpolymerizable cofilin-G-actin complex forms resulting in a decreased rate of polymerization. The data from fluorescence photobleaching recovery experiments at low cofilin-to-actin ratios are consistent with the presence of severed filaments at both pH 8 and 6.6. However, at pH 8 and a cofilin-to-actin ratio of 1:16, about 40-50% of the total actin is present as G-actin after polymerization while at pH 6.6 little or no G-actin is present at the same cofilin-to-actin ratio. The results suggest some cooperativity with respect to cofilin binding to filamentous actin which may be pH dependent.

Actin Depolymerizing Factors↗
PubMed1998

Differential effects of peptide histidine isoleucine (PHI) and related peptides on stimulation and suppression of neuroblastoma cell proliferation. A novel VIP-independent action of PHI via MAP kinase.

The growth rate of rodent embryonic neuroblasts and human neuroblastoma cell lines is regulated in part by autocrine or paracrine actions of neuropeptides of the family that includes vasoactive intestinal peptide (VIP), peptide histidine isoleucine (PHI), and pituitary adenylate cyclase-activating peptide (PACAP). These peptides act via seven transmembrane G-protein-linked receptors coupled to cAMP elevation, phospholipase C activation, intracellular Ca2+ release, and/or of mitogen-activated protein (MAP) kinase activation. Here we investigated the action of these peptides on the mouse neuroblastoma cell line Neuro2a. PHI and VIP inhibited proliferation at concentrations as low as 10(-13) M and 10(-10) M, respectively. In contrast, PACAP action was biphasic, with stimulation occurring at subnanomolar doses and inhibition at higher doses. Peptide actions were studied further by measuring cAMP and ERK1/2 MAP kinase activity and by assessing 3H-thymidine incorporation in conjunction with a panel of signal transduction pathways inhibitors. The data obtained indicated that the PHI-inhibitory and PACAP-stimulatory activities were mediated by corresponding changes in activity of the MAP kinase pathway and independent of protein kinase A (PKA) or protein kinase C (PKC). In contrast, the inhibitory actions of VIP and PACAP were specifically blocked by antagonists of PKA. Northern blot analysis revealed gene expression for only the PACAP-preferring (PAC1) receptor. However, binding experiments using 125I-labeled PACAP27, PHI, and VIP, demonstrated the presence of PACAP-preferring sites, bivalent VIP/PACAP sites, and PHI-binding sites that did not interact with VIP. The studies demonstrate potent regulatory actions of PACAP, PHI, and VIP on neuroblastoma cell proliferation which appear to be mediated by multiple subsets of receptors which differentially couple to MAP kinase and PKA signaling pathways.

Animals↗
PubMed1998

Expression of all known vasopressin receptor subtypes by small cell tumors implies a multifaceted role for this neuropeptide.

Vasopressin is one of several small neuropeptides that are reported to be autocrine growth factors for small cell carcinoma of the lung (SCCL). It has been assumed that this peptide exercises its mitogenic influences through the vasopressin V1a receptor, and we have previously demonstrated that this receptor is expressed by classical and variant SCCL. Activation of the vasopressin V1a receptor produces changes in phospholipases C, D, and A2, in protein kinase C, and in Ca2+ mobilization. This study demonstrates that SCCL cells express not only vasopressin V1a receptors but also mRNAs and proteins representing normal V1b receptors and V2 receptors. They were also shown to express mRNA for a human form of the putative receptor rabbit vasopressin-activated calcium-mobilizing receptor (VACM-1). Additionally, SCCL tumor cells were found to express mRNA and protein representing a possible nonfunctional, shortened, "diabetic" form of the vasopressin V2 receptor that is the product of incomplete posttranscriptional splicing. At least four of these five vasopressin receptors were produced by cell lines exemplifying classical and variant forms of SCCL. No differences in the sequences for the V1 receptors between classical and variant SCCL were found. However, although the nature and expression of both vasopressin V1 receptors and human VACM are apparently unaffected by dedifferentiation in SCCL, only the abnormal (and probably nonfunctional) form of the V2 receptor could be demonstrated in variant cell line NCI H82. Functional engagement of vasopressin V2 receptors is reported to produce rises in cAMP and activation of protein kinase A, whereas stimulation of V1b receptors is believed to produce similar changes to those produced by V1a receptors, i.e., activation of phospholipases and of protein kinase C. Stimulation of VACM receptors raises intracellular free Ca2+ through currently unknown but phosphoinositide-independent mechanisms. The presence of all known vasopressin receptors that are, together, potentially capable of inducing several different transduction cascades in small cell tumor cells suggests that this peptide serves a multifaceted role in tumor physiology.

Animals↗
PubMed1998

Castration decreases extracellular, but increases intracellular, dopamine in medial preoptic area of male rats.

Dopamine (DA) is released in the medial preoptic area (MPOA) of male rats in the presence of a female, and it facilities male sexual behavior. Castration blocks the DA response to a female and the male's ability to copulate. The present experiments examined the effects of castration on (1) basal levels of extracellular DA in the MPOA, using the no net flux microdialysis technique, (2) the response of extracellular DA to amphetamine, and (3) tissue levels of DA. Castrated rats had lower basal levels of extracellular DA in the MPOA, compared with gonadally intact rats; in vivo recovery, a measure of uptake, was not different. This suggests that castration decreases DA release in basal conditions, as well as in response to a female. However, systemic amphetamine injections, which induce DA release, resulted in greater DA release in castrates. Finally, tissue levels of DA were higher in the MPOA, the caudate-putamen and the bed nucleus of stria terminalis of castrates. These data suggest that DA synthesis and storage in the MPOA are normal, or even enhanced, in castrates, and uptake is not altered. The deficit in extracellular levels appears to be related to release, perhaps due to decreased nitric oxide.

Amphetamine↗
PubMed1998

Biodegradation of tricalcium phosphate ceramics by osteoclasts.

Biodegradation of tricalcium phosphate (TCP) ceramics was observed through mixed culture of osteoclasts and TCP discs in vitro in this study. Osteoclasts were isolated from newborn SD rat's marrow of long bone and cultured on TCP discs. The culture terminated at the 48th h and 96th h respectively. Under an inverted microscope, the osteoclasts imparted round or oval body with multinuclear and many thin processes. These cells were positively stained for tartrate-resistance acid phosphatase (TRAP). Scanning electron microscope showed that many resorption lacunae on TCP disc surface and their diameters were smaller than 20 microns. Osteoclasts were located in the lacunae. At the 96th h, the resorption lacunae become larger and osteoclasts showed degeneration. It is suggested that osteoclasts possess ability to re-absorb TCP ceramics under in vitro culturing condition.

Animals↗
PubMed1998

The bacterial inhibitory ability and in vivo drug release pattern of a new drug delivery system: ciprofloxacine/tricalcium phosphate delivery capsule.

The bacterial inhibitory ability of a new drug delivery system (DDS): Ciprofloxacine/tricalcium phosphate delivery capsule (CTDC), its in vivo drug release pattern, and the influence of ultrasonic irradiation on its drug release were investigated. It was found that CTDC had a strong and sustained inhibitory ability to some common pathogens of bone and joint infections, such as staphylococcus aureus, escherichia coli and pseudomonas aeruginosa. In vivo drug-release study in animals demonstrated a high concentration of ciprofloxacine in the bone tissue surrounding CTDC which was placed in the greater trochanter of the rabbit and continued to release ciprofloxacine for at least 5 weeks and the blood level of ciprofloxacine was low. In vivo study also showed ultrasonic irradiation could increase the amount of ciprofloxacine released from CTDC, which may be an economical, effecient and safe new method to achieve the control of drug release from DDS.

Animals↗