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Biomedical subjects

Y Zhang

Publications and source records attributed to Y Zhang.

At least 685 records · Page 38Linked to original sources
PubMed2001

[Studies on neonatal screening, clinical and gene analysis for tetrahydrobiopterin deficiency in Southern Chinese].

OBJECTIVE: To find out the incidence of tetrahydrobiopterin deficiency(BH4D) among patients with hyperphenylalaninemia in Southern Chinese and evaluate the clinical outcome and gene mutations of tetrahydrobiopterin deficient patients. METHODS: Analyses of urinary neopterin(N) and biopterin(B) were done in 87 patients with hyperphenylalaninemia by high-performance liquid chromatography. The patients with BH4 deficiency and their parents were asked to undergo the gene mutation analysis and the patients were treated and followed up. RESULTS: Eleven cases of which the urinary N/B ratio was higher than 38 and B% lower than 5% were diagnosed as BH4 deficiency caused by 6-pyruvoyl-tetrahydropterin synthase(PTPS) deficiency. The incidence of BH4 deficiency among patients with hyperphenylalaninemia is 12% in Southern Chinese. PTPS gene mutations (P87S, N52S, D96N and G144R) were detected from 5 PTPS deficient families. The G144R mutation is a new mutation. The five PTPS-deficient patients were treated with synthetic BH4, neurotransmitter precursors L-dopa and 5-hydroxytryptophan. They had satisfactory physical and mental development after treatment, and 4 of them scored their IQ 70-80. CONCLUSION: The screening for BH4 deficiency should be carried out in all patients with hyperphenylalaninemia in order to minimize the misdiagnoses.

Biopterins↗
PubMed2001

[Measurement of lead in high-salt food with sulfuric-nitric acid to treat food ash].

Lead in high-salt food was measured by treating the ash with sulfuric-nitric acid, and diluting lead standard with sodium sulfate to eliminate the disturbance of chloride in detecting lead with atomic absorption spectrophotometry. The minimum detection limit was 0.10 mg/kg. The relative standard deviation is 1.72%, 5.00% and 7.14% while the amount of lead was 8.70, 2.40 and 1.40 micrograms respectively. The recovery varied between 90.0%-109.0%. There was no significant difference (P > 0.05) of the lead content between the mentioned method and extraction flame photometry. The amount of lead is higher obviously than that of other two methods by eliminating the disturbance of chloride. The method was simple, precise and accurate, and suitable for hygienic examination.

Food Contamination↗
PubMed2001

[Cloning, sequencing and chromosome location of Sry gene of Muntjak munticus vaginalis by DOP-PCR and microdissection].

We isolated 1, Y1, Y2 chromosomes of the male M.m vaginalis by microdissection and amplified the DNA copies by DOP-PCR. Using the DOP-PCR products of 1, Y1, Y2 chromosomes of M.m vaginalis as template respectively and the primers designed within human SRY HMG box, the Sry gene of the male M.m vaginalis was amplified, and it was cloned and sequenced. It is proved that Y2 is the real sex chromosome in the male M.m vaginalis at molecular level for the first time, and Sry was localized on Y2 chromosome.

Animals↗
PubMed2001

Control of p53 ubiquitination and nuclear export by MDM2 and ARF.

p53 and ARF-INK4a are the two most frequently altered loci in human tumors. The activity of p53 protein is inhibited during normal cell growth by the proto-oncoprotein MDM2 through either repression of p53-mediated transcription in the nucleus or proteasomal degradation of p53 protein in the cytoplasm. Responding to oncogenic signal-activated cell hyperproliferation, ARF-mediated antagonism of MDM2 inhibition results in p53 becoming active and its protein levels rising. The biochemical mechanisms of ubiquitination and nuclear export that underlie the functions of ARF and MDM2 in p53 control continue to emerge.

ADP-Ribosylation Factor 1↗
PubMed2001

[Evaluation of biocompatibility on titanium-zicornium alloy].

In this study, the general toxicity tests including cytotoxicity, haemolysis and oral mucous irratation of the Ti-Zr alloy were investigated. The results showed the level of cytotoxicity was grade 0, the haemolysis degree was 0.15% and no histomorphologic change was observed in the animals of Ti-Zr alloy groups. These data indicate that Ti-Zr alloy has good biocompatibility as a dental material.

Alloys↗
PubMed2001

Effects of coexpression of the LDL receptor and apoE on cholesterol metabolism and atherosclerosis in LDL receptor-deficient mice.

The low density lipoprotein receptor (LDLR) plays a major role in regulation of plasma cholesterol levels as a ligand for apolipoprotein B-100 and apolipoprotein E (apoE). Consequently, LDLR-deficient mice fed a Western-type diet develop significant hypercholesterolemia and atherosclerosis. ApoE not only mediates uptake of atherogenic lipoproteins via the LDLR and other cell-surface receptors, but also directly inhibits atherosclerosis. In this study, we examined the hypothesis that coexpression of the LDLR and apoE would have greater effects than either one alone on plasma cholesterol levels and the development of atherosclerosis in LDLR-deficient mice. LDLR-deficient mice fed a Western-type diet for 10 weeks were injected with recombinant adenoviral vectors encoding the genes for human LDLR, human apoE3, both LDLR and apoE3, or lacZ (control). Plasma lipids were analyzed at several time points after vector injection. Six weeks after injection, mice were analyzed for extent of atherosclerosis by two independent methods. As expected, LDLR expression alone induced a significant reduction in plasma cholesterol due to reduced VLDL and LDL cholesterol levels, whereas overexpression of apoE alone did not reduce plasma cholesterol levels. When the LDLR and apoE were coexpressed in this model, the effects on plasma cholesterol levels were no greater than with expression of the LDLR alone. However, coexpression did result in a substantial increase in large apoE-rich HDL particles. In addition, although the combination of cholesterol reduction and apoE expression significantly reduced atherosclerosis, its effects were no greater than with expression of the LDLR or apoE alone. In summary, in this LDLR-deficient mouse model fed a Western-type diet, there was no evidence of an additive effect of expression of the LDLR and apoE on cholesterol reduction or atherosclerosis.

Animals↗
PubMed2001

Biomarker studies on gold-lined sea bream (Rhabdosargus sarba) exposed to benzo[a]pyrene.

Gold-lined sea bream (Rhabdosargus sarba) were intraperitoneally injected with 35 mg/kg benzo[a]pyrene (in DMSO), with fish administered DMSO as the solvent control. Fish were sacrificed 3 days post injection and their livers dissected for the analysis of adenosine triphosphates (ATPase), glutathione-S-transferase (GST), DNA adducts and ethyoxyresorufin-O-deethylase (EROD). Exposure to B[a]P resulted in reduced ATPase activity, elevated GST activity and DNA adduct level, but no apparent change in EROD activity.

Adenosine Triphosphatases↗
PubMed2001

[Hydrodynamic property of internal airlift loop bioreactor with cells immobilized onto ceramic honeycomb support(IALBR-CICHS)].

An internal airlift loop biorector with cells immobilized onto ceramic honeycomb support(IALBR-CICHS) was developed based on the bubble columns(BC) and airlift(AL) bioreactor by installing a ceramic honeycomb support in the draught tube. Their hydrodynamics were respectively studied by the tracer element to determine their retention time distribution (RTD). Experiment and theory analysis indicated that the IALBR-CICHS had more efficacious reactive volume rate(eta) and less short-circuit rate(lambda) for fluid flow compared with the BC and AL bioreactor.

Bioreactors↗
PubMed2001

[Study on the inclusions of xindonin A-beta-cyclodextrin and xindonin B-beta-cyclodextrin].

The inclusions compounds of Xindonin A-beta-cyclodextrin and Xindonin B-beta-cyclodextrin were prepared by the liquid-phase method in aqueous solution. They were confirmed by thin layer chromatography, differential thermal analysis and specific rotation. Changes of ultraviolet spectrum were determined. The composition ratios of inclusion compounds were obtained by the continuous variation method. Solubility of the inclusions were determined.

Cyclodextrins↗
PubMed2001

Language/culture/mind/brain. Progress at the margins between disciplines.

At the forefront of research on language are new data demonstrating infants' strategies in the early acquisition of language. The data show that infants perceptually "map" critical aspects of ambient language in the first year of life before they can speak. Statistical and abstract properties of speech are picked up through exposure to ambient language. Moreover, linguistic experience alters infants' perception of speech, warping perception in a way that enhances native-language speech processing. Infants' strategies are unexpected and unpredicted by historical views. At the same time, research in three additional disciplines is contributing to our understanding of language and its acquisition by children. Cultural anthropologists are demonstrating the universality of adult speech behavior when addressing infants and children across cultures, and this is creating a new view of the role adult speakers play in bringing about language in the child. Neuroscientists, using the techniques of modern brain imaging, are revealing the temporal and structural aspects of language processing by the brain and suggesting new views of the critical period for language. Computer scientists, modeling the computational aspects of childrens' language acquisition, are meeting success using biologically inspired neural networks. Although a consilient view cannot yet be offered, the cross-disciplinary interaction now seen among scientists pursuing one of humans' greatest achievements, language, is quite promising.

Artificial Intelligence↗
PubMed2001

[Organochlorine residues in eggs of night heron breeding in Yuantouzhu, Wuxi and their functions as bioindicator].

This study analyzed chlorinated pesticides in eggs of night heron breeding in Yuantouzhu, Tai lake. The HCH isomers, DDT, DDD, DDE, endrine and heptachlor epoxide were detected out in egg samples. The residue level and the percent of detection of beta-HCH and p,p'-DDE were significantly high. The mean value of p,p'-DDE was 0.906 microgram/g dry weight. Most of the chlorinated pesticides in samples from Wuxi were higher than those of Gongqing city, Jiangxi province. Oppositely, the hatching rate of night heron egg in Wuxi region was lower than that in Gongqing city. It may be related to the difference of DDE residual levels. Using organochlorine residue in eggs of water-fowls as an indicator for environmental quality assessment is feasible.

Animals↗
PubMed2001

[A study on city motor vehicle emission factors by tunnel test].

Applying the principle of tunnel test to run a typical across-river tunnel test in Guangzhou city, 48 h-online-monitor data include pollutant concentration, traffic activity and meteorological data were gained. The average motor vehicle emission factors of NOx, CO, SO2, PM10 and HC were calculated using mass balance which are 1.379, 15.404, 0.142, 0.637, 1.857 g/km. vehicle respectively. Based on that, combined emission factors of 8 types of city vehicles were calculated using linear regression. The result basically showed the character and level of motor vehicle emission in Chinese city.

Vehicle Emissions↗
PubMed2001

[Aerobic sludge granulation and biological phosphorus removal in different operating conditions of SBR].

This paper investigate the effect of the different operating conditions on the aerobic sludge granulation and biological P removal characteristics in SBR by using synthetic domestic wastewater as feed. Different ratios of COD/TN (11.79, 18.85, 20.72, 24.66), COD/TP (27.85, 44.53, 48.93, 58.25), TN/TP (4.00, 2.36, 1.54), temperature(22 degrees C, 15 degrees C, 8 degrees C) and sludge retention time(16d, 10d, 5d) are tested in this process. It is found that the high ratios of COD/TN (24.66), COD/TP (58.25), temperature (22 degrees C) and low SRT (10d) are beneficial to the phosphorus removal and the cultivation of the aerobic granular sludge. The proper TN/TP rate (2.36), dissolved oxygen and selection of anaerobic seed sludge are basic requirement and most important factors to guarantee such aerobic granules in the process.

Aerobiosis↗
PubMed2001

Improved O3/H2O2 oxidation process for wastewater reclamation.

A continuous two step O3/H2O2 oxidation system, in which the waste gas from the former reactor was reused in the latter step with an ejector, was established for the purpose of wastewater reclamation in electronics industries. ORP monitor was combined into the system to obtain the optimum ratio of H2O2 to O3 by automatically adjusting the dosage of H2O2, and ion exchange resin was used for removing organic acids formed during oxidation. The effectiveness of the O3/H2O2 oxidation system for TOC removal was investigated under various conditions by using IPA, DMSO, and NMP as model substances. The optimum H2O2/O3 for oxidizing IPA was in a range above 0.15, and it increased with the increase of O3 dose. A sudden drop of ORP from ca. 800 mV to a little more than 200 mV was observed when H2O2/O3 was approaching the optimum point from the lower end. An ORP between 250 mV and 300 mV or 800 mV and 900 mV was proper for H2O2/O3 control. The treatability of the model substances was in an order of IPA << DMSO < NMP, being consistent with the magnitude of the energy of the highest occupied molecular orbital (epsilon HOMO). The two step treatment system developed in this study was found to be more efficient than the conventional single step system. With the help of H2O2 dosing control and two step treatment using waste O3, the system could save about 40% O3 in comparison with the conventional O3/H2O2 oxidation process.

Conservation of Natural Resources↗
PubMed2001

[Wet synthesis and characterization of fluoride-substituted hydroxyapatite].

Hydroxyapatite and fluoride-substituted hydroxyapatite powders are synthesized by wet method, compacted into pellets and subjected to heat treatment at 300, 600, 900 degrees C respectively. Analysis of the fluoride-substituted hydroxyapatites and HA by FTIR spectroscopy indicated that with the increasing of sintering temperatures, the phase-pure fluoride-substituted hydroxyapatite and stoichiometric hydroxyapatite could be got. According to the X-ray diffraction analysis, the fluoride-substituted hydroxyapatite is less stable for decomposing into beta-Ca3(PO4)2 at the temperature of 900 degrees C. The in vitro bioactivity of the fluoride-substituted hydroxyapatites and hydroxyapatite heat treated at 900 degrees C was assessed by immersion testing in simulated body fluid (SBF). Both scanning electron microscopy (SEM) analysis and ionic solution changes (Ca2+) demonstrated that the low fluoride content apatite could induce a surface bonelike apatite layer formation.

Fluorides↗
PubMed2001

The effect of intraischemic mild hypothermia on focal cerebral ischemia/reperfusion injury.

BACKGROUND: The protective role of intraischemic mild hypothermia on brain injury associated with cerebral ischemia/reperfusion was investigated using a localized, no-flow cerebral ischemia/reperfusion model in rats in vivo. METHODS: Male Wistar rats weighing 250-350 g were anesthetized lightly with halothane. All rats were randomly allocated into two series experiments the first of which was for study of infarct volume and the second of which was for study of NO (nitric oxide) content, and then subjected to various time intervals of focal ischemia followed by reperfusion. The intraischemic mild hypothermia was induced by feedback-regulated semiconductor cooling block in a group of these rats. Normothermia groups were considered as the control groups. The infarct volume and the NO content of rat brain were measured in different groups and hours respectively. RESULTS: The infarct volume of mild hypothermia group was significantly different from that of normal control group within the time window of 10 min (P < 0.05), infarcted brain volumes in hypothermic rats were significantly smaller than in normothermic rats, for the time window of 1 h there was no significant difference in the infarct volume between mild hypothermic group and normothermic control group (P > 0.5). Furthermore, increased tissue levels of NO, a potential mediator of cerebral injury in the brain following focal ischemia were depressed by mild hypothermia. CONCLUSIONS: It is suggested that localized mild hypothermia may be a protective against focal cerebral ischemia/reperfusion injury and that the decreased nitric oxide production in the brain may serve as the protective mechanism of hypothermia.

Animals↗
PubMed2001

Diversity of K+ channels in circular smooth muscle of opossum lower esophageal sphincter.

We previously demonstrated that a balance of K+ and Ca2+-activated Cl- channel activity maintained the basal tone of circular smooth muscle of opossum lower esophageal sphincter (LES). In the current studies, the contribution of major K+ channels to the LES basal tone was investigated in circular smooth muscle of opossum LES in vitro. K+ channel activity was recorded in dispersed single cells at room temperature using patch-clamp recordings. Whole-cell patch-clamp recordings displayed an outward current beginning to activate at -60 mV by step test pulses lasting 400 ms (-120 mV to +100 mV) with increments of 20 mV from holding potential of -80 mV ([K+]I = 150 mM, [K+]o = 2.5 mM). However, no inward rectification was observed. The outward current peaked within 50 ms and showed little or no inactivation. It was significantly decreased by bath application of nifedipine, tetraethylammonium (TEA), 4-aminopyridine (4-AP), and iberiotoxin (IBTN). Further combination of TEA with 4-AP, nifedipine with 4-AP, and IBTN with TEA, or vice versa, blocked more than 90% of the outward current. Ca2+-sensitive single channels were recorded at asymetrical K+ gradients in cell-attached patch-clamp configurations (100.8+/-3.2 pS, n = 8). Open probability of the single channels recorded in inside-out patch-clamp configurations were greatly decreased by bath application of IBTN (100 nM) (Vh = -14.4+/-4.8 mV in control vs. 27.3+/-0.1 mV, n = 3, P < 0.05). These data suggest that large conductance Ca2+-activated K+ and delayed rectifier K+ channels contribute to the membrane potential, and thereby regulate the basal tone of opossum LES circular smooth muscle.

Animals↗