Biomedical subjects

D Zheng

Publications and source records attributed to D Zheng.

At least 37 records · Page 2Linked to original sources

PubMed2001

[Evaluation on the effect of synthetic hydroxyapatite for drinking water defluoridation in field study].

In order to evaluate the effect of synthetic hydroxyapatite on drinking water defluoridation, a coagulative precipitation method and a flow column system was tested in the fields. The defluoridation capacity of coagulative precipitation method was 4.19 mg/g, and the method was simple on operation, but more reagents were needed with high cost for operation. The defluoridation capacity of flow column system was 6 mg/g and the saturated hydroxyapatite could be reused after regeneration. The operation of household defluoridator based on flow column system is simple, with low cost and high capacity in defloridation. The system will be applied in the fluorosis areas.

Durapatite↗

PubMed2001

Acute cardiovascular effects of magnesium and their relationship to systemic and myocardial magnesium concentrations after short infusion in awake sheep.

The temporal relationship between the systemic and myocardial concentrations of magnesium and some of its acute cardiovascular effects were examined after short i.v. infusion administration of magnesium (30 mmol over 2 min) in five awake chronically instrumented sheep. Magnesium decreased mean arterial blood pressure and systemic vascular resistance (SVR) by 23 and 41% from baseline, respectively. These hemodynamic changes were consistent with magnesium producing primary reductions in SVR with partial heart rate (HR)-mediated compensation of blood pressure. Cardiac output and HR increased by 38 and 38% from baseline, respectively. Magnesium had little effect on myocardial contractility, but substantially increased myocardial blood flow (MBF, 77% above baseline) primarily due to direct myocardial vasodilation. The peak arterial and coronary sinus serum magnesium concentrations were 6.94 +/- 0.26 (mean +/- S.E.M.) and 6.51 +/- 0.20 mM, respectively, at 2 min. Both arterial and coronary sinus magnesium concentrations at the end of the study were still more than 3 mM, whereas all the cardiovascular effects were back to baseline. The myocardial kinetics of magnesium was consistent with rapid equilibration of magnesium (half-life 0.4 min) with a small distribution volume (71 ml) consistent with the extracellular space of the heart. In conclusion, magnesium was shown to have a rapid equilibration between the plasma/serum concentrations of magnesium and its extracellular concentration in the myocardium. However, the primary cardiovascular effect of magnesium (reductions in SVR) preceded its extracellular concentrations, and was a direct function of its arterial concentration. A "threshold" model for changes in SVR was preferred when linked to the arterial magnesium concentration.

Animals↗

PubMed2001

Relationship between hyperventilation and intracranial pressure in patients with severe head injury.

With high fatality rate and disability rate, the pathophysiologic changes of severe head injury are complicated. But the method of lowering intracranial pressure (ICP) through artificial hyperventilation is called in question recently. To understand the related changes of the partial pressure of carbon dioxide in artery (PaCO(2)) and the ICP at the acute period of severe head injury, a total of 64 patients with severe head injury were monitored and analyzed on the 3rd day after injury.

Adolescent↗

PubMed2001

[Some issues on assessing natural capital of environment and ecosystems].

Many researchers recently have paid attentions to analyzing ecosystem services and assessing natural capital stocks of environment and ecosystems. However, some works failed to make a distinction among the concepts, to evaluate the value and merit of ecosystems, and to integrate assessment approaches. This paper attempts to calibrate those deviations and to present new paradigm for monetary evaluation of ecosystem services and its capital stocks. Firstly, capital value of environment and ecosystems as well as species' value should be evaluated. Secondly, new comprehensive paradigm should be employed to assess the service value of environment and ecosystems, which integrates type and regional models. Thirdly, special attentions should be paid to patterns of natural capital of environment and ecosystems due to their spatial and temporal accumulations and flows. Finally, some suggestions are proposed for assessing natural capital.

Conservation of Natural Resources↗

PubMed2001

[Analysis on the epidemiology of syphilis in Guangdong province from 1995 - 1999 and the strategy for syphilis control].

OBJECTIVE: To explore the epidemiologic characteristics of syphilis in Guangdong province based on the data from 1995 - 1999 in the province and to provide reference for further control of the disease. METHODS: Registered cases of syphilis were collected in every city/county and the data was analyzed epidemiologically. RESULTS: The incidence rate of syphilis in Guangdong province increased rapidly the past five years, went up from 1.81 per 100 thousand residents in 1995 to 15.17 per 100 thousand residents in 1999 with an average increase as high as 133.37%. The proportion of syphilis in the eight-reportable STD also increased annually with an average annual increase rate of 125.40%. Among the cases, primary cases were dominant accounting for 91.02%. Most patients were males with 20 - 29 year olds accounted for the majority. As for education level, the majority of the patients were middle school graduates. The most popular way of transmission was through extra-marrital sexual contact which accounted for 77.31%. Syphilis patients were mainly seen in coastal cities such as Guangzhou and Shenzhen. CONCLUSION: Based on the epidemiologic feature of syphilis in Guangdong, following measures should be taken in order to control the disease: to enhance the STD knowledge through education, to promote the widely use of condoms and to standardize the diagnosis and treatment of syphilis.

Adolescent↗

PubMed2001

[Study on the relationship between apoptosis and reactive oxygen species of cancer cell lines induced by anticarcinogens].

OBJECTIVE: To investigate the relationship between apoptosis (AP) and fluorescent intensity of reactive oxygen species (ROS) in cancer cell lines induced by anticancer agents, and the mechanisms of drug sensitivity and resistance. METHOD: K562 cells were treated respectively with each of the Vp16, ADR and DDP, the fluorescent intensity of ROS and AP percentage of K562 cells at different concentration of the drugs treated were assayed by flow cytometry (FCM). RESULT: (1) After treatment with these drugs for 24 hours, the fluorescent intensity of ROS and AP percentage of K562 cells increased obviously as compared with that of control groups. (2) The optimum concentrations of the drugs for ROS production and AP of K562 cells were determined. CONCLUSION: Anticancer agents induced AP of K562 cells, which might be through stimulating ROS production.

Antineoplastic Agents↗

PubMed2001

[Optimizing the synthesis of hydroxyapatite as a method for the defluoridation of drinking water].

As the cheaper raw materials for the synthesis of hydroxyapatite as a defluoridator, calcium hydroxide and phosphoric acid are used. Hydroxyapatite is made by a hydro-synthesis method, and optimum conditions are determined by batch test for defluoridation with respect to the consumption of phosphoric acid, reaction time and acid-washed product. The results showed that the defluoridation capacity of the synthetic hydroxyapatite for break through (F- 1.0 mg/L is considered as the break through point) was F- 5.6 mg/g in column test, and F- 10.7 mg/g for saturation in column test. After optimization of the synthesis method, the defluoridation capacity of hydroxyapatite is much higher than activated alumina and bone charcoal, which are used currently.

Fluorides↗

PubMed2001

Foldable lens explantation and exchange: the reason and solution.

OBJECTIVE: To report the explanation and exchange of Hydrophilic Acrylic foldable intraocular lens (IOL) on 14 patients who had visual disturbances caused by the change of transparence on optic. METHODS: Sixteen Hydrophilic Acrylic foldable intraocular lenses from 14 patients who presented with decreased visual acuity from 6 months to 1 year after normal phacoemulsification and IOL implantation associated with extensive transparent change on optic of the lens. The lenses were explanted with the bisection technique. All the eyes were reinserted with Acrysof foldable lenses. RESULTS: Sixteen lenses were removed successfully and exchanged with the new lens in the capsule. The posterior capsular rupture and vitreous loss were found in the first two cases. One of them had the zonulysis due to the radial tear of the anterior capsule during the enlargement of the capsular opening. The anterior vitrectomy was performed with IOL fixed on the ciliary sulcus. The visual acuity of all the patients improved obviously without posterior complication. CONCLUSION: Foldable lens explanation with the bisection technique and exchange had a successful outcome with improvement of ocular condition.

Acrylates↗

PubMed2001

The clinical study of Healon 5 in phacoemulsification and IOL implantation.

PURPOSE: To compare a new ophthalmic viscoelastic device (OVD) Healon 5 with two other kinds of OVDs commonly used in China during phacoemulsification and intraocular lens (IOL) implantation in terms of removal time, intraocular pressure, corneal and anterior chamber response. METHODS: This prospective randomized study, in which patients and observers are masked, comprises niety eyes. They were randomly divided into 3 groups with different OVDs. Healon 5 (sodium hyaluronate 5,000 2.3%) was compared with Healon GV (sodium hyaluronate 7,000 1.4%) and Iviz (sodium hyaluronate 1.0%). The surgeries were performed with temporal corneal incision, phacoemulsification in situ and foldable lens intracapsular implantation. The characteristic and the removal time of the viscoelastic material as well as the postoperative IOP, corneal reaction and anterior chamber reactions of the eyes were observed preoperatively and 24 hrs postoperatively. Exclusion criteria were glaucoma, a preoperative dilated pupil diameter smaller than 5.0 mm, proliferative diabetic retinopathy, significant corneal pathology or a history of uveitis. RESULTS: The removal time was 47.42 +/- 13.09 seconds in Healon 5, 16.50 +/- 5.45 in Healon GV and 15.83 +/- 7.40 in Iviz. The removal time of Healon 5 group was significantly longer than that of the other groups (P = 0.000). There is no significant IOP change 24 hours postoperatively and the difference of intraocular pressure among three groups was not significant (P > 0.05). Healon 5 group had the slightest corneal and anterior chamber response, followed by Healon GV and Iviz. CONCLUSION: Although takes longer time to remove, Healon 5 is an ideal viscoelastic material for its superior space maintenance capacity and high dispersity which provides superior protection of endothelial cells compared to Healon GV and Iviz.

Anterior Chamber↗

PubMed2001

[The inhibitory effect of mitomycin C applied by intracapsular method on rabbit lens epithelial cells: an experimental study of after-cataract].

OBJECTIVE: To study the inhibitory effect of Mitomycin C applied by intracapsular infusion method on rabbit lens epithelial cells and its intraocular toxicity. METHODS: 0.2 ml Mitomycin C with different concentration (0.1 mg/ml, 0.2 mg/ml, 0.4 mg/ml) was injected into the capsular bags of the rabbits' lens during the hydrodissection of phacoemulsification. The drug was exposed to the lens epithelial cells directly and transiently. In the two-month follow-up after the operation, the posterior capsule opacification and the change of intraocular pressure were observed and compared between the control group and the experimental group; the histopathologic and the ultrastructural changes were also observed. RESULTS: For clinical study in the rabbit, the posterior capsule opacification only appeared in the control group two weeks after the operation. Four weeks after the operation, the posterior capsular opacification in the eyes of experimental group was not so obvious as that of the control group. The higher the concentration of the drugs, the less the posterior capsule opacification was shown. There was no obvious difference in the postoperative inflammation between the control group and the low, middle-concentration experimental group. Slight toxic reaction was shown on the rabbits' eyes of the high-concentration experimental group in the early stage after the operation. The histopathologic examination showed that the proliferation of lens epithelial cells in the control group was more obvious than that in the experimental group. Mitomycin C could cause the degeneration of lens epithelial cells. The degree of degeneration was related to the drug's concentration. The ciliary bodies of the rabbits' eyes in the high-concentration experimental group were infiltrated by inflammatory cells and bled slightly. CONCLUSION: Mitomycin C can inhibit the proliferation of lens epithelial cells effectively. Its intensity is related to the drug's concentration. It's a safe and effective drug in the prevention of after-cataract when the concentration of 0.1-0.2 mg/ml was applied in the capsular bag.

Animals↗

PubMed2000

Changes in muscle strength, muscle fibre size and myofibrillar gene expression after immobilization and retraining in humans.

1. Changes in muscle strength, vastus lateralis fibre characteristics and myosin heavy-chain (MyoHC) gene expression were examined in 48 men and women following 3 weeks of knee immobilization and after 12 weeks of retraining with 1866 eccentric, concentric or mixed contractions. 2. Immobilization reduced eccentric, concentric and isometric strength by 47 %. After 2 weeks of spontaneous recovery there still was an average strength deficit of 11 %. With eccentric and mixed compared with concentric retraining the rate of strength recovery was faster and the eccentric and isometric strength gains greater. 3. Immobilization reduced type I, IIa and IIx muscle fibre areas by 13, 10 and 10 %, respectively and after 2 weeks of spontaneous recovery from immobilization these fibres were 5 % smaller than at baseline. Hypertrophy of type I, IIa and IIx fibres relative to baseline was 10, 16 and 16 % after eccentric and 11, 9 and 10 % after mixed training (all P < 0.05), exceeding the 4, 5 and 5 % gains after concentric training. Type IIa and IIx fibre enlargements were greatest after eccentric training. 4. Total RNA/wet muscle weight and ty I, IIa and IIx MyoHC mRNA levels did not change differently after immobilization and retraining. Immobilization downregulated the expression of type I MyoHC mRNA to 0.72-fold of baseline and exercise training upregulated it to 0.95 of baseline. No changes occurred in type IIa MyoHC mRNA. Immobilization and exercise training upregulated type IIx MyoHC mRNA 2.9-fold and 1.2-fold, respectively. For the immobilization segment, type I, IIa and IIx fibre area and type I, IIa and IIx MyoHC mRNA correlated (r = 0.66, r = 0.07 and r = -0.71, respectively). 5. The present data underscore the role muscle lengthening plays in human neuromuscular function and adaptation.

Adult↗

PubMed2000

Characterization of laboratory mutants of Venturia inaequalis resistant to the strobilurin-related fungicide kresoxim-methyl.

Several agricultural fungicides related to the antifungal strobilurins act as inhibitors of respiration by binding to mitochondrial cytochrome b. Two types of laboratory mutants resisting higher doses of the strobilurin-related inhibitor kresoxim-methyl were characterized for Venturia inaequalis, the causal agent of apple scab. Selection of mutagenized conidia by kresoxim-methyl yielded mutants altered in the expression of alternative respiration during the stage of conidia germination. Cytochrome b sequences were not affected in the respective mutants. Selection of conidia on media containing the alternative oxidase inhibitor salicylhydroxamic acid in addition to kresoxim-methyl yielded a highly resistant mutant distinguished by a G143A exchange in cytochrome b. The status of mitochondrial cytochrome b genes remained heteroplasmic, and mitochondria containing wild-type cytochrome b returned to high frequencies during cultivation on inhibitor-free medium. However, continuation of the selection process led to a more pronounced replacement of sensitive by mutated mitochondria. The G143A mutation of cytochrome b causing resistance of V. inaequalis to a strobilurin-related inhibitor has been reported previously for mouse mitochondria; and a permanent G143A exchange rendering naturally resistant mitochondria has been reported for the strobilurin-producing basidiomycete Mycena galopoda and for the sea urchin Paracentrotus lividus. At the corresponding position, alanine was also present in chloroplast cytochrome b6 exhibiting low binding of strobilurin-related inhibitors. The mutation of cytochrome b reported here for V. inaequalis describes the first example of a mutation in filamentous ascomycetes and is part of an assessment of resistance risks inherent to strobilurin fungicides.

Amino Acid Sequence↗

PubMed2000

Protein NMR spectroscopy in structural genomics.

Protein NMR spectroscopy provides an important complement to X-ray crystallography for structural genomics, both for determining three-dimensional protein structures and in characterizing their biochemical and biophysical functions.

Animals↗

PubMed2000

In vivo manipulation and continuous measurement of muscle blood flow with venous effluent sampling.

1. An acute in vivo hindlimb skeletal muscle preparation was developed in anaesthetized sheep in order to facilitate studies of the effects of altered blood flow states on drug kinetics in skeletal muscle. 2. A continuous index of blood flow was recorded via ultrasonic Doppler probes on the femoral artery and vein. Skeletal muscle effluent blood was sampled via a catheter in the femoral vein proximal to the probe. Low- and high-blood flow states were achieved by direct femoral artery infusion of adrenaline (0.002-0.006 mg/min) or magnesium (0.4-1 mmol/min), which produced mean (+/-SD) stable flow states of 25+/-12 and 185+/-56% (both n = 5) of baseline, respectively. The correlation coefficients between arterial and venous Doppler frequency shifts in five sheep during and after adrenaline infusion were 0.96 (indicating these vessels probably supplied and drained common tissue). 3. The venous Doppler frequency shifts were calibrated against timed collections of the femoral vein outflow to provide estimates of the low and normal blood flow states (mean flows of 2.8+/-1.7 and 9.3+/-5.7mL/100 g per min; both n = 3) and against an indirect Kety-Schmidt method during low- and high-blood flow states (mean flows of 2.2+/-1.3 and 18.2+/-7.0 mL/100 g per min; both n = 5). There was a generally good agreement between the two methods. 4. The tissue was neither hypoxic nor acidotic in the low- or high-flow states and altering the flow produced no change in muscle oxygen consumption, suggesting the flow changes were largely due to changes in resistance vessel tone. 5. Postmortem femoral artery dye injection and dissection of stained tissues showed the artery supplied 657+/-96 g (n = 5) of skeletal muscle and 42+/-20 g (n = 5) of other tissues. 6. It is concluded that the method is suitable for sampling predominantly muscle effluent blood at low- or high-blood flow states according to experimental requirements.

Animals↗

PubMed2000

Desulfotomaculum genus- and subgenus-specific 16S rRNA hybridization probes for environmental studies.

Based on comparative analysis of 16S rRNA sequences and the recently established phylogeny of the genus Desulfotomaculum, a set of phylogenetically nested hybridization probes was developed and characterized. A genus-specific probe targets all known Desulfotomaculum species (with the exception of Desulfotomaculum acetoxidans), and five specific probes target subclusters within the Desulfotomaculum genus. The dissociation temperature of each probe was determined experimentally. Probe specificities were verified through hybridizations with pure culture rRNA isolated from a wide variety of target and non-target organisms and through an evaluation of probe 'nesting' using samples obtained from four different environments. Fixation and hybridization conditions for fluorescence in situ hybridizations were also optimized. The probes were used in quantitative membrane hybridizations to determine the abundance of Desulfotomaculum species in thermophilic anaerobic digesters, in soil, in human faeces and in pig colon samples. Desulfotomaculum rRNA accounted for 0.3-2.1% of the total rRNA in the digesters, 2.6-6.6% in soil, 1.5-3.3% in human faeces and 2.5-6.2% in pig colon samples.

Animals↗

PubMed2000

Skeletal muscle kinetics of propofol in anaesthetized sheep: effect of altered muscle blood flow.

1. The kinetics of propofol were studied in vivo in a skeletal muscle bed of the hindlimb of the anaesthetized sheep at normal and low rates of blood flow. 2. Propofol kinetics in muscle were determined during and after a 20-min i.v. infusion of propofol (10 mg min-1) via paired arteriofemoral venous blood sampling. One-and-a-half hours later, the study was repeated but with a concurrent left femoral artery infusion of adrenaline (0.004 mg min-1) to lower the muscle blood flow by vasoconstriction. 3. Muscle blood flow in the low flow state was 28% of that in the normal state. The kinetics were poorly described by a single flow-limited compartment model, but were better described by a model with a flow-limited component and a deeper distribution component. There were no significant differences in muscle retention of propofol between normal and low flow states. 4. There was an apparent arteriovenous shunt of approximately 24% of total muscle blood flow for the low flow state, but not for the normal blood flow state.

Adrenergic Agonists↗

PubMed2000

The presence of humic substances and DNA in RNA extracts affects hybridization results.

RNA extracts obtained from environmental samples are frequently contaminated with coextracted humic substances and DNA. It was demonstrated that the response in rRNA-targeted oligonucleotide probe hybridizations decreased as the concentrations of humic substances and DNA in RNA extracts increased. The decrease in hybridization signal in the presence of humic substances appeared to be due to saturation of the hybridization membrane with humic substances, resulting in a lower amount of target rRNA bound to the membrane. The decrease in hybridization response in the presence of low amounts of DNA may be the result of reduced rRNA target accessibility. The presence of high amounts of DNA in RNA extracts resulted in membrane saturation. Consistent with the observations for DNA contamination, the addition of poly(A) to RNA extracts, a common practice used to prepare RNA dilutions for membrane blotting, also reduced hybridization signals, likely because of reduced target accessibility and membrane saturation effects.

DNA, Bacterial↗

PubMed2000

Plasma endothelin-1 levels and circulating endothelial cells in patients with aortoarteritis.

To investigate the correlation between plasma endothelin-1 (ET-1), circulating endothelial cells (CECs), and the disease activity in patients with aortoarteritis. In this study, radioimmunoassay was used to measure plasma levels of ET-1 in 56 patients with aortoarteritis. Circulating endothelial cell counts were also carried out as an indicator of vessel wall lesions. The plasma levels of ET-1 and CECs in the active disease patient group were significantly higher than those in inactive patient group (p<0.001). A significant positive correlation was found between plasma ET-1 levels and erythrocyte sedimentation rates (ESRs) in patients with aortoarteritis (r=0.645, p<0.001), as well as CECs (r=0.876, p<0.001). These results suggested that the ET-1 secreted during the active stages of aortoarteritis may cause constriction and proliferation of vascular smooth muscle cells, thus contributing to the pathogenesis of luminal narrowing. The increased CECs might serve as a marker of disease activity.

Adult↗