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Biomedical subjects

M Shao

Publications and source records attributed to M Shao.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Effects of soil moisture and shading levels on photosynthetic characteristics of cotton leaves].

The effects of different soil moistures and shading levels on stomatal conductance(Gs), net photosynthetic rates(Pn), transpiration and leaf water potential(LWP) of cotton (variety Zhongmian No. 23) grown in pots from the seedling to flower bud stages in summer noon were evaluated. We designed three shading levels: no-shading(CK), 75% shading (DN), 40% shading(SN); and three soil moistures; 85%-100% (high water, HW), 65%-85% (medium water, MW) and 45%-65% (low water, LW) of field water-bolding capacity. The Gs of DN and SN increased by 16.69% and 28.01% compared with CK at HW, respectively, while the Pn of DN and SN declined by 45.74% and 20.54%, respectively. The Gs of DN and SN enhanced by 28.86% and 23.28% compareds with CK at MW, respectively, while the Pn of DN and SN decreased by 31.97% and 1.64%, respectively. The Gs of CK, DN and Sn did not exhibit significant differences at LW, while Pn of DN and SN reduced by 46.22% and 13.45%, respectively. Significant difference in Gs did not exist between DN and SN at the same soil moisture, but there was significant difference in Pa between them (except at LW). It was suggested that Gs declined with the increasing of leaf-to-air vapor pressure difference (VPD) and showed weak correlation with Pn by regression. The combined effects of soil moistures and shading levels on LWP and transpiration rate were not significant. There was no significant difference in LWP and transpiration rate among three shading treatments. Contrasted to treatment CK, intercellular CO2 concentration (Ci) in DN and SN at HW, MW and LW increased significantly, except no apparent change of Ci in SN at MW.

Carbon Dioxide↗
PubMed2000

Bilateral pallidotomy for treatment of idiopathic Parkinson's disease.

OBJECTIVE: To clarify the benefits and risks of patients undergoing bilateral posteroventral pallidotomy (BPVP) for patients with idiopathic Parkinson's disease (PD) and the differences between contemporaneous BPVP (CBPVP) and staged BPVP (SBPVP). METHODS: Twenty patients underwent microelectrode-guided CBPVP and 26 SBPVP for bilateral PD symptoms. The data were retrospectively reviewed. Unified Parkinson's Disease Rating Scale (UPDRS) was used to evaluate the effects of these operations. RESULTS: BPVP, either CBPVP or SBPVP, significantly improved patients' bilateral PD symptoms (P < 0.001). The improvement was consistently higher in "off" state than in "on" state. No statistical difference was observed in the improvement percentages of CBPVP, SBPVP1 and SBPVP2. CBPVP contributed greatly to L-dopa induced side effects (part IV). BPVP, SBPVP1, and SBPVP2 significantly improved cardinal parkinsonian signs but no difference was found among them. One patient after CBPVP developed hypophonia and swallowing problem, while 2 patients after SBPVP sustained hypophonia. These conditions were improved 3 months later. CONCLUSIONS: BPVP may significantly improve bilateral signs of PD. It is safer than bilateral thalamotomy. CBPVP is applicable to some patients. BPVP may not cause mental impairment but shows a higher incidence rate of hypophonia. The practice of BPVP requires a refined surgical technique and a better understanding of pathophysiology of the basal ganglia.

Adult↗
PubMed2000

[Simultaneous pallidotomy and thalamotomy for Parkinson's disease with intractable tremor].

OBJECTIVE: To evaluate the clinical necessity, outcomes, safety, and indications of contemporary combined pallidotomy and thalamotomy for Parkinson's disease (PD) with intractable tremor. METHODS: The UPDRS data from 20 patients who received simultaneous pallidotomy and thalamotomy were analyzed retrospectively. During the same period, 326 patients were subjected to unilateral pallidotomy. Improvement and complications between the two groups were compared. RESULTS: Contemporary pallidotomy and thalamotomy effectively improved parkinsonian symptoms as did pallidotomy alone. This procedure completely abolished intractable tremor in all 20 patients. No permanent complications occurred. CONCLUSIONS: Contemporary combination of pallidotomy and thalamotomy is effective and safe in treating regular parkinsonian symptoms and intractable tremor.

Adult↗
PubMed2000

[Modulation of GABA-activated currents by oxytocin in rat dorsal root ganglion neurons].

Experiments were performed on freshly isolated dorsal root ganglion (DRG) neurons of rat. GABA(A)-activated currents were recorded using the whole-cell patch clamp technique. The majority of the neurons (48/52, 90.5%) were sensitive to GABA (10( 6)~10( 3) mol/L). Application of oxytocin (OT) induced outward membrane responses in 51.3% (20/39) of the neurons, no apparent responses in 43.6% (17/39) and inward responses in 5.1% (2/39). 10( 12), 10( 11), 10( 10) and 10( 9) mol/L OT increased 10( 4) mol/L GABA-activated currents to 24.1+/-7.6% (n=6), 33.4+/-6.9% (n=9), 40.2+/-6.5% (n=13) and 67.2+/-14.8% (n=5), respectively. After preapplication of OT, the Kd value for GABA(A)-activated currents decreased, while the response obtained at the maximum concentration increased. The results suggest that the enhancement of GABA-activated currents by OT may suppress primary sensory transmission by potentiating pre-synaptic inhibition of GABA.

Animals↗
PubMed2000

[Fibronectin in adhesion, spreading and proliferation of mandibular condylar cartilage cells on cytodex-3 microcarrier].

OBJECTIVE: The purpose of this study was to investigate the effects of exogenous fibronectin on the attachment and growth of mandibular condylar cartilage (MCC) cells on DEAE-dextran micro-carrier. METHODS: MCC cells were harvested from newborn New Zealand white rabbits by sequential digestion with trypsin and collagenase. They were grown on the 20 mg/L fibronectin-coated and uncoated cytodex-3 micro-carrier. Samples were collected after 1, 3, 5, 7, 9, 11 days. The kinetics of adhesion and growth were observed with phase contrast microscope and environmental scanning electronic microscope (ESEM) and quantified by 0.1% crystal violet nuclear extrusion method. RESULTS: MCC cells could rapidly attach and spread onto the fibronectin-coated cytodex-3, and nearly 60 percent cells attached to the micro-carrier within 2 hours. Spreading cells were flat and lowly refractile observed under phase contrast microscope. While the attachment and spreading of the cells in the untreated group were slow, and only 36 percent cells attached to the uncoated micro-carrier. However, most cells attached to the micro-carrier in both groups after 24 hours. The MCC cells attaching to FN-coated cytodex-3 observed under ESEM were flatter and adhered tightly with more processes (pseudopodia) stretching out from cytoplasm. In contrast, cells on untreated cytodex-3 remained regularly round even 24 hours after being plated. Meanwhile, there was an accelerated growth rate of the MCC cells on the fibronectin treated cytodex-3. The cell density in the FN treated group was higher than that of the untreated group at the end of the culture. CONCLUSION: Fibronectin, one major glycoprotein of extracellular matrix, plays an important role in cell attachment and spreading. The better understanding of the extracellular matrix will be helpful in selecting the optimal substrate for cell growth in vitro.

Adhesiveness↗
PubMed1999

Enhancement of GABA-activated current by muscarine in rat dorsal root ganglion neurons.

The modulation of GABA-gated ion channel responses to GABA, pentobarbital and diazepam by muscarine was studied in freshly isolated rat dorsal root ganglion neurons using a whole-cell patch-clamp technique. Muscarine enhanced current activated by 5 microM GABA dose-dependently with an EC50 of 40 +/- 2 microM. This potentiation was not blocked by pirenzepine, gallamine and atropine, the specific and non-specific muscarinic receptor antagonists. Muscarine shifted the GABA dose-response curve to the left, with the GABA EC50 decreased from 45 +/- 2 to 13 +/- 2 microM. The maximal response to GABA was suppressed to 89.3 +/- 4.6% as compared with the control (100%) by 80 microM muscarine. Muscarine potentiated GABA (1-100 microM)-activated current in a voltage-independent manner. Muscarine shifted the dose-response curve for pentobarbital enhancement of GABA-activated current to the left, and the enhancement of GABA-activated current by muscarine was additive to that of pentobarbital over all pentobarbital concentrations. Muscarine shifted the dose-response curve for diazepam (1-100 nM) enhancement of GABA-activated current to the left. However, muscarine attenuated the facilitatory effect of saturating concentrations of diazepam (> 100 nM). The potentiating effect of muscarine was blocked by 1 nM ethyl-beta-carboline-3-carboxylate, the inverse agonist of benzodiazepine receptors. These results suggest that GABA-gated ion channel responses to GABA and pentobarbital were potentiated by muscarine and the binding site(s) for muscarine might be related to those for diazepam.

Acetylcholine↗
PubMed1999

[A clinical analysis of L-dopa induced dyskinesia treated by posteroventral pallidotomy for Parkinson's disease].

OBJECTIVE: To evaluate the outcome of microelectrode-guided posteroventral pallidotomy (PVP) for L-dopa induced dyskinesia in patients with Parkinson's disease. METHODS: Thirty-six patients with dyskinesia were evaluated with unified Parkinson's disease rating scale (UPDRS) before and after operation. Duration and disability of dyskinesia were analyzed respectively. RESULTS: The total surgical improvement for dyskinesia was 76.2%. Duration improvement was 88.8% and disability 79.7%. Significant change (P < 0.05) happened postoperatively. Seventeen patients were followed up for 3 months. The result showed a stable improvement for dyskinesia. CONCLUSIONS: L-dopa induced dyskinesia may disappear or be improved after PVP. Surgical treatment promises a maximum L-dopa therapy without any severe pharmaceutical complications. Synergic treatment of drug and surgery are a new strategy for Parkinson's disease.

Adult↗
PubMed1998

[Association between the debrisoquine hydroxylase gene polymorphism and the genetic susceptibility of Parkinson's disease].

OBJECTIVE: To clarify the relation of the debrisoquine hydroxylase gene polymorphism with the genetic susceptibility of Parkinson's disease. METHODS: The debrisoquine hydroxylase gene polymorphisms were analyzed with the polymerase chain reaction-restriction fragment length polymorphism methods in 100 cases of Parkinson's disease and 100 age-,sex-matched normal controls. RESULTS: It was found that the frequencies of A and B mutation of debrisoquine hydroxylase gene in group of patients were higher than those in the controls, and the risk of suffering Parkinson's disease increased 2 times. In group of the patients, the frequencies of C188-->T, G4268-->C and C2938-->T were also higher than those in the controls. Especially in those with C2938-->T mutation, the risk of suffering the disease increased 2.58 times. CONCLUSION: The result suggested that the defect of the detoxifying enzymes might be a factor contributing to the genetic susceptibility of Parkinson's disease.

Adult↗
PubMed1998

X-ray studies on cross-linked lysozyme crystals in acetonitrile-water mixture.

Tetragonal crystals of hen egg white lysozyme were cross-linked and subjected to X-ray diffraction study in acetonitrile-water media with different acetonitrile concentrations. Crystals in neat acetonitrile did not scatter X-ray well. Structures of crystals in neat water, in 90% and 95% acetonitrile, and crystal back-soaked from acetonitrile to water, were determined to about 2 A resolution. For crystals in both 90% acetonitrile, and crystal back-soaked from acetonitrile to water, were determined to about 2 A resolution. For crystals in both 90% and 95% acetonitrile, only one protein-bond acetonitrile molecule is found in the active site cleft, and its location and binding-protein mode is similar to the C subunit of polysaccharide. The alteration in conformation and hydrogen-bond pattern involving water as solvent causes the reduction of the protein's flexibility in organic media. The back-soaked crystal regained its ordinary three-dimensional structure in water.

Acetonitriles↗
PubMed1998

Determination of the amino acid neurotransmitters in the dorsal root ganglion of the rat by capillary electrophoresis with a laser-induced fluorescence-charge coupled device.

A sensitive, rapid and accurate analysis of the amino acid neurotransmitters in dorsal root ganglion (DRG) of rat was accomplished by capillary electrophoresis with a laser-induced fluorescence-charged coupled device (LIF-CCD) and fluorescein isothiocyanate (FITC) derivatization. Since the CCD is an image detector with a matrix array of photoelements, the photogenerated charge generated from single photoelements was summed up by on-chip charge binning, and used to improve the detection sensitivity. A self-compiled data processing program was used to calculate digitally the summation of the multiwavelength data and transform three-dimensional electropherograms into two-dimensional electropherograms. Use of this program improved the detection sensitivity, the extraction of useful statistical data and the performance of the quantitative analysis. Owing to its excellent detectability and the unique characteristic of its two-dimensional format, which allows to perform analog and digital summation, high detection sensitivity with detection limits ranging from 1.2 to 17.2 nM was obtained for the amino acid neurotransmitters by LIF-CCD. This method was demonstrated to be a powerful tool for analyzing the complex biological samples through quantitative determination of the six amino acid neurotransmitters in the DRG of rat.

Animals↗
PubMed1998

[Fibrinolytic properties and thrombolytic effect of a novel fibrinolytic enzyme from Streptomyces sp. Y405].

A novel protease (designated as SW-1) purified from the fermentation broth of Streptomyces sp. strain Y405 showed fibrinolytic activity. In vitro, on plasminogen-free fibrin plate which had been heated at 85 degrees C for 30 minutes to eliminate plasminogen, SW-1 showed the same fibrinolytic activity as the mixture of SW-1 and plasminogen. Without adding plasminogen into the fibrin clot tube SW-1 showed the same effect as with plasminogen (P > 0.05). The results might indicate that SW-1 is a fibrinolytic enzyme which degrades fibrin directly, but not a plasminogen activator which degrades fibrin by activating plasminogen. SW-1 was found also to degrade fibrinogen. In vivo, the thrombolytic effect of SW-1 (4000 u.kg-1) on venous thrombus in rat was most remarkable versus that of control(P < 0.001), but was not divergent versus that of urokinase at the some dose(P > 0.05). SW-1 was shown to enhance plasminogen and plasmin activity but did not show significant effect on endogenous t-PA or alpha 2-PI. SW-1 also caused decrease of fibrinogen level in plasma, indicating that it degrades the fibrin in thrombus and at the same time degrades the circulating fibrinogen to certain extent. The changes of these biochemical data demonstrated the thrombolytic properties of SW-1 in vivo.

Animals↗
PubMed1997

Statistical framework for ultrasonic spectral parameter imaging.

This study examines the statistics of ultrasonic spectral parameter images that are being used to evaluate tissue microstructure in several organs. The parameters are derived from sliding-window spectrum analysis of radiofrequency echo signals. Calibrated spectra are expressed in dB and analyzed with linear regression procedures to compute spectral slope, intercept and midband fit, which is directly related to integrated backscatter. Local values of each parameter are quantitatively depicted in gray-scale cross-sectional images to determine tissue type, response to therapy and physical scatterer properties. In this report, we treat the statistics of each type of parameter image for statistically homogeneous scatterers. Probability density functions are derived for each parameter, and theoretical results are compared with corresponding histograms clinically measured in homogeneous tissue segments in the liver and prostate. Excellent agreement was found between theoretical density functions and data histograms for homogeneous tissue segments. Departures from theory are observed in heterogeneous tissue segments. The results demonstrate how the statistics of each spectral parameter and integrated backscatter are related to system and analysis parameters. These results are now being used to guide the design of system and analysis parameters, to improve assays of tissue heterogeneity and to evaluate the precision of estimating features associated with effective scatterer sizes and concentrations.

Carcinoma↗
PubMed1996

Feedback shift register sequences versus uniformly distributed random sequences for correlation chromatography.

Two alternative input sequences are commonly employed in correlation chromatography (CC). They are sequences derived according to the algorithm of the feedback shift register (i.e., pseudo random binary sequences (PRBS)) and sequences derived by using the uniform random binary sequences (URBS). These two sequences are compared. By applying the "cleaning" data processing technique to the correlograms that result from these sequences, we show that when the PRBS is used the S/N of the correlogram is much higher than the one resulting from using URBS.

Algorithms↗
PubMed1996

Solid-phase synthesis, metal binding and folding properties of caulimovirus-related 'zinc finger'.

A 17-residue peptide containing the caulimovirus-related "zinc finger' was prepared by solid-phase peptide synthesis. Fluorescence measurements showed that the tryptophan quantum yield was Zn(2+)-dependent, allowing a 1:1 a stoichiometry for the complex to be determined. The structure of the peptide was characterized using circular dichroic spectroscopy, which indicates that the peptide exhibits a random coiled conformation in the absence of zinc but appears to form an ordered structure in the presence of zinc.

Amino Acid Sequence↗
PubMed1994

[Auto-analysis of corneal endothelium with photoelectrical scans and computer].

A quantitative analysis of corneal endothelial cells was made with photoelectrical scans and computer in 67 eyes. No difference was found as regards to the mean cell area and density between the endothelial analysis system and routine square counting. On the other hand, we analyzed corneal endothelial cells between 30 eyes wearing hard contact lens and 30 eyes of age- and sex-matched nonwearing control. The parameters, including cell density individual cell area, area, mean cell area, standard deviation, coefficient of variation of cell size (CV), maximum cell, minimum cell, the ratio of the maximum to minimum cell, and percentage of the hexagoal cells, were automatically displayed. The cell density and mean cell area also showed no significant difference (P > 0.05) between the wearers and nonwearing control, but the CV and the frequency of the hexagonal cells showed significant difference (P < 0.01). The ratio of maximum to minimum cell, the polymegethism and pleomorphism were obviously increased in the wearers. It is highly suggested that computer analysis system is of great value in evaluating corneal endothelial cells.

Adolescent↗
PubMed1991

Experimental study on the corneal endothelium of traumatic cataract.

The cell morphology of corneal endothelium in 84 mice with experimental traumatic cataract was investigated with stained corneal buttons. In the experimental group, the boundaries between adjacent corneal endothelial cells were significantly distorted, some cell boundaries manifested degenerative changes that led to coalescence of the cells. The mean density and mean area of endothelial cells of the controls showed significant difference from those of the experimental group during the 12 weeks of observation. The density of endothelial cells decreased from 3,312 +/- 337/mm2 of the control group to 2,944 +/- 418/mm2 in the group of partially opaque lenses and 2,713 +/- 472/mm2 in the group of totally opaque lenses. Meanwhile, the area of endothelial cells and the coefficient of variation also significantly changed correspondingly, and the degree of damage in the corneal endothelium correlated with the degree of the lens opacity.

Animals↗
PubMed1991

[Survey of fungi and bacterinum of the conjunctival sac in Guangzhou area].

This paper presents the results of fungal culture from healthy conjunctival sac in 178 eyes. The rate of positive culture of the fungi was 25% in farmers, 11.1% in cleaners, and 8.8% in city residents respectively. Culture for aerobic was carried out in the samples from conjunctival sacs of 137 eyes. The rate of positive culture was 71.9% in farmers, 80.6% in cleaners, and 23.2% in city residents respectively. On the other hand, the rate of fungal positive culture was 9.7% and that of aerobic was 30% in the patients managed with steroid eyedrops for more than one month. The aspergillus and penicillium were the most commonly seen species among the isolated fungal strain, whereas the staphylococci and streptococcus pneumonia were the most common among the isolated aerobic. The results run parallel to the fact that the main pathogens of ocular infection seen clinically are fungi and aerobics. The authors emphasize that the conjunctival sac should be disinfected to prevent infections caused by opportunistic pathogens.

Adolescent↗