Search PubMed⌕ Search

Biomedical subjects

H Qian

Publications and source records attributed to H Qian.

At least 127 records · Page 7Linked to original sources
PubMed1997

The time course of malondialdehyde production following impact injury to rat spinal cord as measured by microdialysis and high pressure liquid chromatography.

This paper reports a highly sensitive, specific, and reproducible method for the analysis of malondialdehyde (MDA) from microdialysates. The microdialysates were reacted with 2-thiobarbituric acid, and the TBA adducts were separated by HPLC and detected using a fluorescence detector. Butylated hydroxytoluene was used as an antioxidant to minimize formation of artifacts. The time course of MDA production following impact injury to the rat spinal cord was obtained using this improved method. MDA concentrations in the extracellular space gradually increased from a basal level of 20 +/- 3.6 nM to 44 +/- 18.1 nM during the first 2 hr, reached a maximum of 95 +/- 19.8 nM at 5 hr, and then decreased to 36 +/- 9.5 nM at 9 hr. The findings support the hypothesis that spinal cord injury leads to increased membrane lipid peroxidation.

Animals↗
PubMed1997

Utilization of phytate phosphorus and calcium as influenced by microbial phytase, cholecalciferol, and the calcium: total phosphorus ratio in broiler diets.

The present study was performed to evaluate the potential of microbial phytase and cholecalciferol (D3) for improving the utilization of phytate P and Ca and the influence of the Car:total (t) P ratio in a corn-soybean meal diet fed to broilers from hatch to 21 d of age. A 4 x 4 x 2 factorial arrangement of treatments was used: 1.1, 1.4, 1.7, and 2.0:1 Ca:tP ratio; 0, 300, 600, and 900 U of phytase/kg of diet; and 66 and 660 micrograms of D3/kg of diet. Another four treatments were included: the four Ca:tP ratios with 6,600 micrograms of D3 addition, but without phytase. Added phytase linearly increased (P < 0.001) BW gain, feed intake, toe ash content, and P and Ca retention; these measurements were negatively influenced by widening the dietary Ca:tP ratio, and synergetically improved by addition of D3. Increasing the Ca:tP ratio decreased (P < 0.001) all measurements in the presence or absence of supplemental phytase and D3. Dietary Ca:tP ratios between 1.1:1 to 1.4:1 appears critical to the efficient use of supplemental phytase and D3 for improving the utilization of phytate P and Ca. The addition of D3 in corn-soybean meal diets indicated a potential for improving the utilization of phytate P and Ca by increasing Ca and P retention by about 5 to 12% in birds, which led to an increase in toe ash content (P < 0.03). The enhanced phytate P utilization (P < 0.001) was also observed during assay of the phytase activity in the mixed diets with an addition of D3 and without added phytase. In summary, the findings of this study suggested that phytase, D3, and Ca:tP are important factors in degrading phytate and improving phytate P and Ca utilization in broilers.

6-Phytase↗
PubMed1997

GABA receptors of bipolar cells from the skate retina: actions of zinc on GABA-mediated membrane currents.

GABA receptors of bipolar cells from the skate retina: actions of zinc on GABA-mediated membrane currents. J. Neurophysiol. 78: 2402-2412, 1997. gamma-Aminobutyric acid (GABA)-induced currents were recorded from isolated bipolar cells of the skate retina using perforated patch-clamp methodology. Pharmacological analysis of the responses, using selective agonists and antagonists of the major classes of GABA receptor, revealed the presence of both GABAA and GABAC receptors at both the dendrites and axon terminals of the bipolar cells. The two receptor types showed very different reactions to zinc, a divalent metallic cation that was detected in the synaptic terminal region of skate photoreceptors. Currents mediated by the activation of GABAC receptors were down-regulated by zinc, a feature that is typical of the action of zinc on GABAC receptors. On the other hand, the effects of zinc on GABAA receptor-mediated activity was highly dependent on zinc concentration. Unlike the GABAA receptors on other neurons, responses mediated by activation of the GABAA receptor of skate bipolar cells were significantly enhanced by zinc concentrations in the range of 0. 1-100 mu M; at higher concentrations of zinc (>100 mu M), response amplitudes were suppressed below control levels. The enhancement of GABAA receptor activity on skate bipolar cells showed little voltage dependence, suggesting that zinc is acting on the extracellular domain of the GABAA receptor. In the presence of 10 mu M zinc, the dose-response curve for 4,5,6, 7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP; a GABAA agonist that suppresses GABAC-activated currents) was shifted to the left of the curve obtained in the absence of zinc, but without a significant change in the response maximum. This finding indicates that the enhancing effect of zinc is due primarily to its ability to increase the sensitivity of the GABAA receptor. The novel enhancement of neuronal GABAA receptor activity by zinc, observed previously in the GABAA-mediated responses of skate Müller (glial) cells, may reflect the presence of a unique subtype of GABAA receptor on the bipolar and Müller cells of the skate retina.

Animals↗
PubMed1997

[Bronchofiberscope and catheter intervention in treatment of multi-drug resistant pulmonary tuberculosis].

OBJECTIVE: To evaluate the clinical value of bronchofiberscope and catheter intervention in treatment of multi-drug resistant pulmonary tuberculosis. METHOD: Forty-eight patients with multi-drug resistant pulmonary tuberculosis were treated by injecting ofloxacin and amikacin through bronchofiberscope and catheter in addition to chemotherapy, while forty controls were treated by chemotherapy only. RESULT: At the end of the treatment, the sputum conversion rate was 92%, radiographic improvement rate 96% and cavity closing rate 27% in the treatment group, all of which were higher than the controls (63%, 58% and 10% respectively) (P < 0.01-0.05). No complication and obvious adverse reaction were observed. CONCLUSION: The efficacy of bronchofiberscope and catheter intervention in addition to chemotherapy is better than only chemotherapy in treatment of multi-drug resistant pulmonary tuberculosis.

Adult↗
PubMed1997

[Assay of terpenes in the leaves of Ginkgo biloba extract and its preparations by in situ fluorometric TLC].

A new TLC method for the assay of terpene lactones in Ginkgo biloba extract and its preparations has been established by means of optimized development condition and post-chromatographic thermal fluorescence derivatization. Satisfactory results can be obtained through polynomial regression calibration. The data obtained by this method have been proved ten times higher in sensitivity than those obtained by HPLC-refracto-detector.

Chromatography, High Pressure Liquid↗
PubMed1997

[The development and application of an hand-held gamma detecting probe].

A new device for tumor to perform radioimmunoguided surgery (RIGS) was described, The instrument was based on the inverse square law that the sensitive and specificity of the detector increase as the distance between the source and the detector shorted. The experimental results showed that the hand-held gamma detecting probe was practical to perform radioimmuoguided surgery for tumor in vivo.

Animals↗
PubMed1997

Vaccination with monoclonal anti-idiotypic antibody on immunocompetent mice bearing human ovarian carcinoma.

OBJECTIVE: To observe the effects of anti-idiotypic monoclonal antibody 6B11 against ovarian carcinoma SKOV3 on immunocompetent mice BCF1 both in vivo and in vitro, so as to investigate the possibility of using it as a tumor vaccine. METHODS: After immunization with 6B11 and normal mice (NM) IgG respectively on 2 groups of BCF1, blood, lymphocytes and tumor tissues were taken every other day. Ab3 was tested from blood samples. Subpopulations of lymphocytes were examined by FCM. The lymphocytes from immunized BCF1 were also cultured with SKOV3 to observe the chemotaxis and killing effects. Serial tissue sections were taken from BCF1 after immunization by SRCA implantation of SKOV3. TIL and visible cancer cells were examined carefully and compared with those in the controls. RESULTS: Ab3 rose quickly after immunization with 6B11 but lowered down gradually till the 9th week. The CD4+/ CD8+ ratio of BCF1 changed markedly after immunization with 6B11. The immunized lymphocytes showed a beautiful chemotaxis with and killing effect on SKOV3. During in vivo examinations, TIL were found significantly earlier in the immunized BCF1 than in the controls and reached the peak earlier in the former (on the 6th day) than in the latter, while the viability of tumor cells was vice versa between the two groups. CONCLUSION: 6B11 may be used as a vaccine for not only active immunization but also prevention of ovarian carcinoma.

Animals↗
PubMed1997

[Preparation of F(ab')2 fragment of monoclonal antibody COC166-9 and its experimental study of radioimmunoimaging for ovarian carcinoma].

OBJECTIVES: To obtain F(ab')2 fragment of monoclonal antibody (McAb) COC166-9 and to perform its radioimmunoimaging (RII) for ovarian carcinoma. METHODS: McAb COC166-9 was digested into F(ab')2 by ficin and tested by SDS-PAGE. After purification by DEAE-32, F(ab')2, COC166-9 and normal murine IgG (nMIgG) were labelled by 131I and injected intraperitoneally into three groups of nude mice bearing human ovarian cancer xenografts respectively. 72 hours after injection, RII was performed in three groups of mice. RESULTS: The yield of F(ab')2 was 54%, about 80% of the maximal theoretical yield. Good immunoreactivity of F(ab')2 retained with higher ratio of tumor to normal tissue radioactivity (T/NT) than that of intact COC166-9. RII showed better result with lower nonspecific background than the latter. CONCLUSION: F(ab')2 could be obtained by ficin digestion with good yield and immunoactivity as well as better RII than intact monoclonal antibody.

Animals↗
PubMed1997

[Treatment and prognostic factors of epithelial ovarian cancer].

OBJECTIVE: To study the treatment results and prognostic factors of epithelial ovarian carcinoma. METHODS: Retrospective study of 155 cases of ovarian epithelial carcinoma admitted in our hospital since Jan. 1970 to Dec. 1992. All of these cases had postoperative pathological diagnosis and staging according to FIGO. 42 cases had second operations and 4 cases had the third. 149 cases had postoperative chemotherapies except for 6. Chemotherapies were also given to 32 cases after the second operation, while 9 for recurrence. RESULTS: The 2-year, 5-year, 10-year survival rates of stage I were 92.4%, 87.0%, 70.6%; and II 91.9%, 63.6% 47.8%; III 59.9%, 38.2%, 19.2% and IV 25.0%, 25.0%, 0.0% respectively. All 6 cases without chemotherapy after surgery died within 2 years. The results indicated that the prognosis of ovarian epithelial carcinoma was related to clinical stage, cellular grade and tumor residues. The 5-year survival rates for stage I was 87.0% and III 38.2% (P < 0.001); and cell G1 95.0% and G3 11.8% (P < 0.001), while no residual tumor 97.6% and with residual tumor > 2cm 21.2% (P < 0.001) respectively. CONCLUSION: Residual tumor of ovarian epithelial carcinoma < 2cm after primary surgery and chemotherapy right after surgery can improve survival rates.

Adolescent↗
PubMed1996

Interactions between a helical residue and tertiary structures: helix propensities in small peptides and in native proteins.

We compare three complete sets of helix propensities for the 20 naturally occurring amino acids. These propensities are derived from three different experimental systems: small synthetic peptides, coiled-coil dimers, and real proteins. Thermodynamic analyses show that propensities from the different sets should be perfectly correlated if (1) the helix in a protein is formed when and only when the protein is folded (tight-coupling); and (2) the amino acid side-chains are not involved in tertiary interactions. A simple thermodynamic model is proposed in order to understand those systems that fail (1). The model incorporates fluctuations in both native and unfolded states of the protein. Measurements on hydrogen-exchange rate from proteins also question the validity of (2). A complementary model that assumes a cooperation between helix formation and tertiary structures through side-chain interactions can explain the correlation between data from the peptides and proteins. One possible source of this side-chain tertiary interaction is the amphiphilicity of helices in proteins. Our model is consistent with the ideas of "minimal frustration" and "protein malleability"; it exhibits entropy-enthalpy compensation, and suggests that local unfolding and solvent penetration are correlated in a fluctuating protein. It also suggests experiments to quantitatively verify and differentiate between the models. The electrostatic nature of hydrogen bonding and its manifestations in protein helix stability is also discussed.

Amino Acids↗
PubMed1996

Zinc enhances ionic currents induced in skate Müller (glial) cells by the inhibitory neurotransmitter GABA.

We describe here a novel effect of zinc on GABA receptors of glial cells in the skate retina. The GABA-induced currents of skate Müller cells, the radial glia of the retina, are mediated by activation of GABA(A) receptors (GABAARS). In other parts of the nervous system, GABz*-)ediated currents are inhibited by zinc. However, in isolated, voltage-clamped Müller cells, coapplication of zinc (10 microM) and GABA (1 microM) resulted in enhancement of the GABA(A)R current. Surprisingly, zinc alone induced a current similar in many respects to that elicited by GABA, i.e. the reversal potential was the same as for the GABA-induced current, the current was blocked by bicuculline and picrotoxin, and the current-voltage relation obtained in the presence of 10 microM zinc was virtually identical to that obtained with 1 microM GABA. Both bicuculline and picrotoxin suppressed a current that was present with cells bathed only in Ringer, suggesting that some of the GABA channels were spontaneously open in the absence of externally applied GABA. This possibility was supported by cell-attached patch recordings. Under conditions in which potassium and calcium currents were suppressed, spontaneous channel activity was observed. Moreover, the frequency of these channel openings was greater when zinc was included in the pipette solution, and reduced when bicuculline was added. These findings suggest that zinc acts directly to enhance the GABA(A) receptor activity of the Müller cells, and raise the possibility that the subunit composition of the GABA(A)Rs of skate Müller cells differs from that of GABA(A)Rs identified previously in other neuronal and glial preparations.

Animals↗
PubMed1996

Prediction of alpha-helices in proteins based on thermodynamic parameters from solution chemistry.

Current studies on the protein folding problem are chiefly pursued by two approaches; one statistically investigates the three-dimensional structures of proteins and the other focuses on their thermodynamic properties in solution. It remains to be demonstrated that information from these two sources are consistent and complementary. Using two sets of thermodynamic parameters experimentally obtained from solution studies, namely the helix propensities derived from small model peptides and hydrophobicity based on solvent transfer free energies for amino acids, we predict alpha-helices in native proteins. The correlation coefficient of our predictions on 98 non-homologous proteins is 0.26, a value comparable to that of the statistical prediction of Chou & Fasman but less than that from the state of the art prediction (0.39) based on neural network methodology. Helix propensities derived from different experimental systems in aqueous solutions are highly consistent for predicting alpha-helices in proteins. The helix propensities and amphiphilicity in primary sequences make independent contributions to the occurrence of alpha-helices. We also show that, with appropriate models, statistical analyses of known three-dimensional structures can provide thermodynamically relevant quantities. These findings indicate that for practical helix prediction, various sets of propensities have reached reasonable consensus. The report also suggests integrating solution thermodynamic studies with protein structural analyses, and the role of supersecondary structures on helices in proteins.

Databases, Factual↗
PubMed1996

Effects of supplemental phytase and phosphorus on histological, mechanical and chemical traits of tibia and performance of turkeys fed on soyabean-meal-based semi-purified diets high in phytate phosphorus.

Tibial traits were investigated for turkey poults fed on soyabean-meal-based semi-purified diets high in phytate P (2.2 g/kg) with added phytase and inorganic P. Dietary treatments were: (1) 2.7 g non-phytate P (nP)/kg; (2) diet 1 + 1000 U phytase/kg diet; (3) 3.6 g nP/kg; (4) diet 3 + 800 U phytase; (5) 4.5 g nP/kg; (6) diet 5 + 600 U phytase; (7) 6.0 g nP/kg. Added phytase and nP increased (P < 0.006) tibial dry matter, ash weight and content, body-weight gain, feed intake and gain:feed. The Mg and Zn concentrations in the tibial ash were also increased (P < 0.001 and P < 0.09 respectively) by added phytase or nP; tibial P and Ca concentrations tended to be increased. Hypertrophy zone width of the tibial proximal end decreased (P < 0.001), while proliferating zone width, tibial length, and widths at the long and short axes increased (P < 0.003) as phytase and nP were added. The addition of phytase also tended to enlarge the cartilaginous zone width, which was linearly increased (P < 0.05) by added nP. Disorganization scores of the hypertrophy zone and trabecular bone were low, approaching normal (P < 0.05), for turkey poults fed on diets with phytase supplementation, and tibial abnormality scores were linearly decreased (P < 0.001) as nP levels increased (zero score is considered normal). Adding phytase and nP improved the orderliness of development, mineralization and arrangement of cartilage and bone cells, and alleviated the effects of P deficiency on the histological and gross structure of the tibias. Tibial shear stress increased (P < 0.04) as phytase and nP were added. In summary, similar improvements in bone characteristics were achieved for turkey poults fed on a P-deficient diet supplemented with either phytase or nP.

6-Phytase↗
PubMed1996

Replacement of inorganic phosphorus by microbial phytase for young pigs fed on a maize-soyabean-meal diet.

Ninety-six crossbred young pigs (body weight 7.8 kg) were used in a 5-week trial to determine the effectiveness of microbial phytase (EC 3.1.3 26) in improving the bioavailabilities of P and other nutrients in maize-soyabean-meal diets and, thus, replacing inorganic P with phytase. A 2 x 5 factorial arrangement of treatments was employed with two available P (aP) levels (0.7 and 1.6 g/kg) and five phytase levels (0, 350, 700, 1050, 1400 U (the quantity of enzyme that liberates 1 mumol inorganic phosphate/min from 5.1 mm-sodium phytate at pH 5.5 and 37 degrees)/kg diet). In addition, two extra diets were formulated to supply the National Research Council (1988) recommended level of aP (3.2 g/kg) with 0 or 1400 U phytase. The addition of graded levels of phytase resulted in linear increases in average daily weight gain, average daily feed intake and weight gain:feed intake for pigs fed on diets containing 0.7 or 1.6 g aP/kg (P < 0.04). Also, the addition of phytase linearly increased apparent digestibilities of P and Ca (P < 0.01), whereas faecal P excretion was linearly decreased (P < 0.01). Linear increases in shear force, shear energy and ash content of both the metacarpal and tenth rib, and shear stress of the metacarpal were found to respond to added phytase (P < 0.01). These improvements in performance, apparent P absorption and bone measurements by phytase were also observed by increasing dietary aP levels for most measurements. Adding 1400 U phytase to the 3.2 g aP/kg diet further increased average daily weight gain, average daily feed intake, apparent absorption of P, Ca and N and metatarsal shear force and ash content (P < 0.01 to 0.05). Generally, maximum responses occurred at a phytase level of 1050 U/kg diet for the 0.7 g aP/kg diets and 700 U for the 1.6 g aP/kg diets. Based on non-linear and linear response equations generated for the phytase and aP levels, the average function of the equivalency of P (Y, g/kg) v. microbial phytase (X, U/kg) was developed across aP levels of 0.7 and 1.6 g/kg for average daily weight gain and apparent digestibility of P: Y = 2.622-2.559e 0.00185X. The replacement of 1 g inorganic P as defluorinated phosphate would require about 246 U microbial phytase. This represents 41% of released P from phytate.

6-Phytase↗
PubMed1996

Adverse effects of wide calcium:phosphorus ratios on supplemental phytase efficacy for weanling pigs fed two dietary phosphorus levels.

Ninety-six weanling pigs (initial BW = 9.3 kg, initial age = 37 d) were used in a 4-wk experiment to evaluate the response to three Ca: total (t) P ratios (1.2:1, 1.6:1, or 2.0:1) fed in combination with two P levels (.07 or .16% available that correspond to .36 or .45% tP) and two phytase levels (PY; 700 or 1,050 units/kg of diet). A 3 x 2 x 2 factorial arrangement of treatments was employed using a corn-soybean meal diet. Performance, serum mineral concentrations and alkaline phosphatase (ALP) activity, Ca and P digestibility and excretion, and bone mechanical measurements were examined. Average daily gain (P < .001), average daily feed intake (P < .01), and gain:feed (P < .05) were decreased linearly as the Ca:tP ratio became wider. The digestibility of P and Ca were decreased (P < .001) linearly as the Ca:tP ratio became wider. The digestibility of P (P < .001) and fecal P excretion (P < .01) were increased at the higher level of P. Increasing PY from 700 to 1,050 units (U)/kg of diet increased (P < .05) P digestibility and decreased (P < .01) P excretion but did not improve bone measurements. Shear force, stress and energy, and percentage of ash of both metacarpal and 10th rib linearly decreased (P < .001 to .05) as the Ca:tP ratio became wider, and bone measurements were generally greater for pigs fed the higher P level. Serum Ca concentration increased (P < .01) and the P concentration decreased (P < .001) as the Ca:tP ratio increased, but Mg, Zn, and ALP activity were not influenced by the Ca:tP ratio. Serum Ca and P concentrations were affected by PY supplementation over the 4-wk trial, but serum Mg and Zn concentrations were not affected by dietary treatments. Adverse effects of a wide Ca:tP ratio were greater at the low P diet for all responses. In addition, the activity of supplemental PY in diets seemed to be decreased as the Ca:tP ratio became wider and this negative effect of Ca:tP ratio seemed greater at the low P level, and seemed to parallel the effects of Ca:tP ratio on performance, P digestibility, bone, and serum measurements. Narrowing the dietary Ca:total P ratio from 2.0:1 to 1.2:1 led to an approximate 16% increase in phytase efficacy for improving performance, digestibility, bone measurements, and serum Ca levels.

6-Phytase↗