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Biomedical subjects

D Shi

Publications and source records attributed to D Shi.

At least 73 records · Page 4Linked to original sources
PubMed1998

Expression of the mouse metallothionein-I gene conferring cadmium resistance in a transgenic cyanobacterium.

This paper reports the construction of a transgenic strain of cyanobacterium aimed at removing heavy metal pollution in waters. The mouse metallothionein-I (mMT-I) gene was inserted in the vector pRL-439 downstream of the strong psbA promoter. The resulting plasmid pRL-MT was ligated at the EcoRI site of the shuttle vector pKT-210 to generate the shuttle expression vector pKT-MT. This recombinant plasmid was introduced into Anabaena sp. PCC 7120 by triparental conjugative transfer. After selection on streptomycin, a stable transgenic Anabaena strain was obtained. The presence of the mMT-I gene was confirmed by DNA/DNA hybridization and its expression was demonstrated by immunodetection with specific antibodies. A metal tolerance experiment showed that this transgenic Anabaena strain had acquired higher metal resistance.

Anabaena↗
PubMed1998

Coating of hydroxyapatite on highly porous Al2O3 substrate for bone substitutes.

A thin film of hydroxyapatite (HA) was successfully coated onto a highly porous substrate of alumina by using a novel solution technique. The coated HA bonded strongly to the substrate through a glass sintering aid with an intermediate thermal expansion coefficient. The coating was also found to be microstructurally and chemically uniform on the surfaces of the interconnected pores in the matrix of the substrate. Mechanical property testing results showed that the strength of the HA-coated composite was significantly improved, indicating a high potential for structural bone substitutes in hard tissue prosthetics.

Aluminum Oxide↗
PubMed1998

Deficits in smooth-pursuit eye movements after muscimol inactivation within the primate's frontal eye field.

To evaluate smooth-pursuit (SP) function in the primate frontal eye field (FEF), microinjections of muscimol, a gamma-aminobutyric acid (GABA) agonist, were used to reversibly deactivate physiologically characterized sites in FEF. SP was severely impaired by deactivation at sites in the FEF's smooth eye movement region (FEFsem) located in the fundus and posterior bank of the macaque monkey's arcuate sulcus. These SP deficits were apparent immediately after the muscimol injection and persisted for several hours but recovered by the next day. SP was most drastically and consistently impaired for directions similar to the injected site's elicited smooth eye movement direction or to the optimal SP direction for its neuronal responses. Targets moving in these directions, usually ipsilateral to the injected hemisphere, were tracked primarily with saccades after the muscimol injection, the peak SP velocity being only 10-30% of preinjection velocity. SP in other directions, including contralateral, was less strongly affected. Initial SP acceleration in response to target motion onset was also significantly diminished, generally by approximately the same proportion as peak SP velocity. In contrast, saccades were largely unaffected by muscimol injections in FEFsem; nor was there an immediate effect on SP when control sites in the saccadic region of FEF (FEFsac) were deactivated, although a SP deficit often appeared 30-60 min after FEFsac injections, possibly reflecting diffusion of muscimol into neighboring FEFsem. These reversible SP deficits produced by muscimol inactivation within FEFsem are similar to permanent deficits caused by large aspiration lesions of FEF and indicate that inclusion of FEFsem is the critical factor determining whether FEF lesions impair SP. The severity of the reversible deficits found here indicates how extremely critical FEFsem is for normal highgain SP.

Animals↗
PubMed1998

Clinical observation on 84 cases of ventricular premature beat with deficiency syndrome treated by qi lu tang.

From August 1989 to May 1994, 84 cases of ventricular premature beat (VPB) with deficiency syndrome were treated with our empirical prescription called Qi Lü Tang Decoction for Improving Abnormal Heart Beat). The total effective rate was 88.10%, being significantly different from that of the control group treated with the Western drug propafenone (P < 0.01). Qi Lü Tang exhibited a better therapeutic effect in cases of VPB with deficiency of qi, deficiency of both qi and blood, and deficiency of both qi and yin.

Adult↗
PubMed1998

[The comparison of radiosensitivity between uterine cervical squamous carcinoma and adenocarcinoma].

OBJECTIVE: To compare the radiosensitivity of uterine cervical squamous carcinoma and adenocarcinoma. METHODS: The shrinkage of tumor and the radiation-induced damage were compared between cervical squamous carcinoma and adenocarcinoma after twice afterloading radiotherapy. Proliferating cell nuclear antigen index (PI), detected immunohistochemically, was compared before and after radiotherapy between the two tumors. RESULTS: Patients of squamous carcinoma with tumor shrinkage 50% or more accounted for 70% (21/30) and patients of adenocarcinoma accounted for 27% (4/15), which was statistically significant (P < 0.01). The radiation-induced damage grade II b-III accounted for 60% (18/30) in squamous carcinoma and for 20% (3/15) in adenocarcinoma, which was statistically significant (P < 0.05); PI decreased from 53.50% +/- 4.34% to 39.30% +/- 4.02% after radiotherapy in squamous carcinoma (P < 0.001), while PI decreased from 35.47% +/- 3.83% to 31.80% +/- 3.06% in adenocarcinoma (P > 0.05). CONCLUSIONS: The radiosensitivity of cervical squamous carcinoma is higher than that of adenocarcinoma. The decrease of PI after radiotherapy may be a biological basis of radiosensitivity for uterine cervical squamous carcinoma.

Adenocarcinoma↗
PubMed1998

[Nucleoside diphosphate kinase/nm23H1 expression in ovarian epithelial carcinoma: retroperitoneal lymphatic metastasis and survival].

OBJECTIVE: To determine the relationship between NDPK(A) expression and retroperitoneal lymph node metastasis (LNM) and the significance of the prognosis in epithelial ovarian carcinoma. METHODS: NDPK(A) expression of formalin-fixed parafin-beded samples, which included 74 primary, 31 intraperitoneal and 18 retroperitoneal lymph node metastatic tumors, were examined by ABC immunohistochemisty in 74 patients with primary ovarian cancer. RESULTS: In the 74 primary lesions, 22 samples showed positive staining of NDPK(A) (30%). Positive staining was higher in patients without LNM(46%) than those with LNM (17%, P = 0.008); it was lower in menopausal patients (19%) than in menstruant (44%, P = 0.022). Compared with primary tumor, NDPK(A) expression appeared to decrease in lymph-node lesion(28% vs 39%, P > 0.1) but to increase in intraperitoneal metastastic tumor (32% vs. 19%, P > 0.5). Multivariance analysis confirmed that the important risk factors for LNM were lower expression of NDPK(A), more large residual tumor and poor differentiation. But there was no any corelation between NDPK(A) expression and survia. CONCLUSION: The study suggested that increased expression of NDPK(A)/nm23H1 is inversely related to LNM in epithelial ovarian carcinoma, but it can not confirm the prognostic significance of NDPK(A).

Female↗
PubMed1998

[Effect of purified Xuefu capsule on cardiac haemodynamics and oxygen consumption in acute myocardial ischemia of experimental dogs].

OBJECTIVE: To investigate the effect of Purified Xuefu Capsule (PXC) on cardiac haemodynamic and oxygen consumption in acute myocardial ischemia of experimental dogs. METHODS: The coronary arteries was ligated to create the myocardial ischemic modle and gave them PXC through the duodenum. The effect of PXC on the systolic and diastolic function, volume of blood flow in coronary arteries and cardiac output of acute ischemic heart of experimental dogs were examined. RESULTS: After ligation of the coronary artery the myocardial ischemia was formed, the systolic and diastolic function, volume of blood flow in coronary arteries and cardiac output were decreased significantly in the control group, whereas these indexes in high-dose and low-dose PXC group were improved to some extent, the effect of high-dose PXC group was better than that of the low-dose PXC group. Furthermore high-dose PXC could reduce the oxygen consumption. CONCLUSIONS: PXC could prevent the cardiac pump function from acute myocardial ischemia of experimental dogs. The mechanism may be related to reduce the oxygen consumption and increase the blood supplement to myocardium.

Animals↗
PubMed1998

[Observation on the surface characteristics of the leaves of Dysosma and its related genus by scanning electronic microscope].

OBJECTIVE: To observe the surface characteristics of leaves of Dysosma and its related genus by SEM for identification. METHOD: Leaf surface characteristics of seven species of Dysosma and tow species of its related genus were observed by scanning electronic microscopic method. RESULT: The leaf surface characteristics of upper epidermis and lower epidermis of the nine plants are different from each other. A key and illustrations were listed. CONCLUSION: The leaf surface characteristics observed by SEM can be used for identification of Dysosma and its related plants.

Magnoliopsida↗
PubMed1998

[Perilunate progressive instability of the wrist: a study of wrist dynamics].

OBJECTIVE: To study the changes in dynamics of wrist motor tendons after perilunate instability of the wrist. METHODS: 14 cadaver upper extremities were used. Excursions of the principle wrist and finger motor tendons were measured during wrist flexion-extension and radiolunar deviation was determined. Data were collected in the intact wrist, then in the wrist with stage I, II and III perilunate instability. The average moment arms of the tendons during wrist motion were calculated. RESULTS: The moment arms of the wrist flexors increased and those of the finger flexors decreased after instability. Increase in the moment arms dominated changes of radial side wrist motors, while decrease in the moment arms dominated ulnar wrist motors. Moment arms of the flexor carpi radialis tendon showed a consistent increase during wrist motion. CONCLUSION: The changes in wrist dynamics play an important role in clinical manifestations of perilunate instability. The significance of kinetic information on principle of treatment of the instability is discussed.

Biomechanical Phenomena↗
PubMed1998

[Inhibitor of plasminogen activator 1 (PAI-1) in hepatocellular carcinoma].

OBJECTIVE: To study the expression of the type-1 inhibitor of plasminogen activator (PAI-1) on protein and mRNA in hepatocellular carcinoma (HCC), and the relation between PAI-1 and biological behaviour of HCC. METHOD: The tumor specimens of HCC (n = 48) and benign liver tumor (contorl n = 12) were tested by immunohistochemistry for the expression of PAI-1 protein. The tumor specimens of HCC (n = 20) and normal liver tissue (contorl n = 5) were evaluated by Northern blot analysis for the expression of PAI-1 mRNA. RESULT: PAI-1 protein and PAI-1 mRNA were higher in tumor cell than in the marginal tissue of tumor and in control (P < 0.01 and P < 0.05). In deaths 2 years after surgery, PAI-1 was increased as compared to the survival group (P < 0.05). When negative PAI-1 conupared with positive urokinase-type plasminogen activator (uPA) and positive uPA receptor (uPAR). The nambeigs invasion case increased, the difference was more significant than that in the group with negative PAI-1, uPA and uPAR (P = 0.039). CONCLUSION: The expression of PAI-1 protein and PAI-1 mRNA is increased in HCC. PAI-1 contributes to the invasion, metastasis and prognosis of HCC.

Blotting, Northern↗
PubMed1997

Diverse genetic regulatory motifs required for murine adenosine deaminase gene expression in the placenta.

Murine adenosine deaminase (ADA) is a ubiquitous purine catabolic enzyme whose expression is subject to developmental and tissue-specific regulation. ADA is enriched in trophoblast cells of the chorioallantoic placenta and is essential for embryonic and fetal development. To begin to understand the genetic pathway controlling Ada gene expression in the placenta, we have identified and characterized a 770-base pair fragment located 5.4 kilobase pairs upstream of the Ada transcription initiation site, which directs reporter gene expression to the placenta of transgenic mice. The expression pattern of the reporter gene reflected that of the endogenous Ada gene in the placenta. Sequence analysis revealed potential binding sites for bHLH and GATA transcription factors. DNase I footprinting defined three protein binding regions, one of which was placenta-specific. Mutations in the potential protein binding sites and footprinting regions resulted in loss of placental expression in transgenic mice. These findings indicate that multiple protein binding motifs are necessary for Ada expression in the placenta.

Adenosine Deaminase↗
PubMed1997

[Preliminary observation of MRI manifestations of adult pulmonary tuberculosis].

OBJECTIVE: To study the role of MRI in diagnosis of adult pulmonary tuberculosis. METHODS: MRI and X-ray appearance of 55 adult pulmonary tuberculosis cases were reviewed. RESULTS: No obvious difference was found between the images of MRI and chest radiography which reflect infiltrative and proliferative pathologic changes of pulmonary tuberculosis (including cavity, tuberculoma and caserous pneumonitis). Infiltrative, proliferative lesions and caserous pneumonitis showed middle signal on the T1 and T2 weighted images. Cavity showed low signal. Tuberculoma showed generally hyterogenous signal on the T2 weighted images. CONCLUSION: It is unnecessary to use MRI as a routine tool for diagnosis of pulmonary tuberculosis.

Adult↗
PubMed1997

[The preparation of poly (DL-lactide) hollow fiber and the release of drug in vitro].

The biodegradable hollow fibers of DL-PLA were prepared by a dry-wet phase inversion spinning process. By using four different spinning systems, DL-PLA hollow fibers with varying asymmetric membrane structure were obtained. The structure of hollow fiber wall was examined by SEM. In vitro release of norethisterone from the DL-PLA hollow fibers was also investigated. The hollow fibers were filled with a 50 wt% NET in castor oil. The DL-PLA hollow fibers NET release was found to be dependent on the membrane structure of the hollow fiber wall. Possible release mechanisms were discussed.

Delayed-Action Preparations↗
PubMed1996

Spiropyrrolizidines: a new class of blockers of nicotinic receptors.

The spiropyrrolizidine oximes 236 and 222 and a related spiropyrrolizidine alkaloid, nitropolyzonamine, block nicotinic receptor channels in rat pheochromocytoma PC12 cells and in human medulloblastoma TE671 cells. In PC12 cells with an alpha 3 beta 4(5)-nicotinic receptor, both the spiropyrrolizidine oxime 236 and nitropolyzonamine had IC50 values of about 1.5 microM, while spiropyrrolizidine oxime 222 had an IC50 value of 2.6 microM versus carbamylcholine-elicited sodium-22 influx. In TE671 cells with an alpha 1 beta 1 gamma delta nicotinic receptor, the spiropyrrolizidine oximes 236, 222, and nitropolyzonamine had IC50 values of 9.5, 14, and 67 microM, respectively. The inhibitions by the spiropyrrolizidine oxime 236 and nitropolyzonamine appeared to be noncompetitive in nature in both cell lines. In rat cerebral cortical membranes, binding of [3H]nicotine to alpha 4 beta 2 nicotinic receptors was not inhibited significantly by 10 microM concentrations of the spiropyrrolizidine oxime 236, or by nitropolyzonamine, as expected for a noncompetitive blocker. Both compounds at 10 microM had marginal effects on a variety of central receptors, but did inhibit binding of [3H]1,3-di(2-tolyl) guanidine to sigma receptors in mouse brain membranes with IC50 values of about 0.5 microM. The spiropyrrolizidine oxime 236 at 10 microM had no effect on batrachotoxin-elicited sodium influx in guinea pig cerebral cortical synaptoneurosomes or on ATP-elicited calcium influx in PC12 cells. Such spiropyrrolizidines represent a new structural class of blockers of nicotinic receptor channels with selectivity for ganglionic-type receptors.

Animals↗
PubMed1996

Vasoactive intestinal peptide: mediator of laminin synthesis in cultured Schwann cells.

To learn more about neuropeptide-induced glial responses which accompany axon regeneration, we studied effects of VIP on laminin production by cultured Schwann cells. Schwann cells were isolated from sciatic nerves of neonatal mice, purified, and incubated for 5 days in either control medium (DMEM + 15% FCS) or control medium containing 10-7 -10-11 M VIP. At 10-7 and 10-8 M VIP, laminin levels measured by enzyme-linked immunosorbent assay were significantly higher (55% and 35%) than those in control cultures. Lower VIP concentrations (10-9 -10-11 M) produced smaller increases which were not significant. Low-affinity VIP receptors which mediated this effect were demonstrated on Schwann cells by radioligand binding studies. The increased Schwann cell synthesis of laminin induced by VIP was blocked when either a VIP antagonist or a VIP receptor antagonist was added to the VIP-containing incubation medium. In contrast to astrocytes, when Schwann cells were loaded with fura-2, VIP did not increase cytosolic Ca2+. This indicates that Schwann cells and astrocytes may have different intracellular transduction pathways; their receptor subtypes also may differ. We suggest that the VIP-induced increase in laminin synthesis which we have observed in cultured Schwann cells may also occur in vivo and might be an important component of axon-Schwann cell interactions during nerve regeneration.

Animals↗
PubMed1996

Tetrahydrobenzothiophenone derivatives as a novel class of adenosine receptor antagonists.

A novel class of non-nitrogen-containing heterocycles, the tetrahydrobenzothiophenones, was found to bind to adenosine receptors as antagonists in the micromolar range. Affinity was determined in radioligand-binding assays at rat brain A1 and A2a receptors. A structure-activity analysis indicated that a 3-thioether group is favored and affinity at A2a, but not at A1, receptors is highly dependent on this thioether substituent. A carboxylic acid-derived substituent is required at the 1-position of the thiophene ring, with esters being more potent in binding at A1 receptors than the corresponding carboxyl hydrazide or carboxylic acid derivatives. The methyl (15) and ethyl (16) esters are about equipotent at A1 but not at A2a receptors. A 4-keto group on the saturated ring is favored for receptor affinity. Dimethyl substitution at the 6-position of the saturated ring is allowed. One of the most potent derivatives was the nonselective compound ethyl 3-(benzylthio)-4-oxo-4,5,6,7-tetrahydrobenzo[c] thiophene-1-carboxylate (BTH4, 7; Figure 1), which antagonized adenosine agonist-induced inhibition of adenylyl cyclase in rat adipocyte membranes with a KB value of 1.62 +/- 0.73 microM and adenosine agonist-induced stimulation of adenylyl cyclase in pheochromocytoma cell membranes with a KB value of 9.19 +/- 0.98 microM. Displacement of radioligand binding by BTH4 (7) at cloned human A3 receptors was negligible but one slightly A3 selective compound (11, 3.9-fold over A1 and >7.5-fold over A2a) was found. A 1-methylpropyl thioether (17) was 29-fold selective for A1 and A2a receptors. BTH4 (7) alone, at 10 mg/kg, stimulated locomotor activity in mice but paradoxically acted, under certain circumstances, synergistically with an A1 selective agonist to depress locomotor activity. A pharmacophore model relating structural features of xanthine and non-xanthine adenosine antagonists to BTH4 (7) suggests a high degree of similarity in electrostatic surfaces, assuming that the thiophene ring superimposes the region of the uracil ring of xanthines.

Animals↗