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Biomedical subjects

Q Zheng

Publications and source records attributed to Q Zheng.

At least 73 records · Page 4Linked to original sources
PubMed1999

[Internal fixation for zygomatic arch fracture with super-high molecular weight poly D, L-lactic acid mini-plates and screws: a study in dogs].

OBJECTIVE: To investigate the internal fixation effects of super high molecular weight (Mv = 6.0 x 10(5) kD) poly D, L-lactic acid(PDLLA) mini-plates and screws. METHODS: 10 dogs were utilized in this experiment with the self-contrast study method, comparing with the titanium mini-plates and screws. RESULTS: The mechanical properties of the PDLLA mini-plates and screws appeared to be sufficient to enable undisturbed healing of depressed zygomatic arch fracture. CONCLUSION: The good fixation effect of PDLLA mini-plates and screws was as same as that of the titanium mini-plates and screws without the need of secondary operation.

Animals↗
PubMed1999

[Tissue reaction and degradation of super-high molecular weight poly D, L-lactic acid mini-plates and screws: an animal experiment].

OBJECTIVE: To investigate the tissue reaction and degradation processes of the super-high molecular weight(Mv = 6.0 x 10(5) kD) poly D, L-lactic acid(PDLLA) mini-plates and screws through the internal fixation for zygomatic arch fracture. METHODS: It was carried out by the self-contrast study method and comparing with the titanium mini-plates and screws. RESULTS: There was no side-effects on bone healing. The reaction of soft and hard tissues to PDLLA mini-plates and screws was similar to that of the titanium mini-plates and screws. No complication had been seen with the use of PDLLA mini-plates and screws, including infection, foreign body reaction and underlying osteolysis. The PDLLA devices had no changes in shape after 3 months, and then became the grains in different sizes after 6 months, and were completely resorbed within 12 months in vivo. CONCLUSION: The super-high molecular weight PDLLA mini-plates and screws has good biocompatibility and proper degradation time. It is safe and effective to use the mini-plates and screws made of the super-high molecular weight PDLLA for internal fixation of bone.

Animals↗
PubMed1999

[Study of cleft palate with problems of middle ears and its treatment].

OBJECTIVE: To gain a clear idea of the following: 1. the relationship between the incidence of functional obstruction of middle ear and surgery on cleft palate and patients' age; 2. the bacterial culture of secretion taken from the tympanic cavity with secretory otitis media; 3. the preliminary effects of treatment by inserting a tube into the tympanic cavity of a patient with secretory otitis media. METHODS: 275 middle ears of patients with cleft palate were selected, then acoustic immitence examination and hearing threshold of pure tone were adopted, and bacterial culture was carried out for studying secretion of the middle ear with secretory otitis media. RESULTS: The tympanograms of 75.5% ears of the patients before cleft palate operation were found to be abnormal, among which patients under 3 years were 81%, and 41.2% ears of those after closure of cleft palate were abnormal. Gram's positive and negative germs of bacterial culture were 20.1% and 24% respectively. The hearing of 6 ears with secretory otitis media has recovered from the moderate hearing loss due to tube insertion. And the tympanograms of 4/8 ears were transformed from type B to type A. CONCLUSION: It is beneficial to improve function of Eustachian tube if cleft palate can be repaired at an early stage and beneficial to improve the patients' hearing and devlope their speech if a tube is inserted into the typanic cavity in cases of secretory otitis media at an early stage.

Adolescent↗
PubMed1999

[Biocompatibility of self-designed absorbable hydroxyapatite/poly (DL-lactide) composites].

The biocompatibility of self-designed hydroxyapatite/poly (DL-lactide) rods was evaluated both in vitro and in vivo including Ames test, micronucleus test, acute and subacute systemic toxicity test, hemolysis test, hemopexis test and long-term muscle and bone implant test. The results indicate that the material has no toxicity, no stimulation and mutation, and it does not cause hemolysis and hemopexis. Consequently, the biocompatibility of the composite was good.

Absorbable Implants↗
PubMed1999

[Structural disorder and conformation difference in the organic molecular crystals].

OBJECTIVE: Investigating multiple configuration nature of natural organic molecules through study on atom disorder in crystal state molecules. METHODS: Three-dimensional determination for four natural organic compound samples by using single crystal X-ray diffraction. RESULTS: Through disorder analysis on molecules in crystal state, we have found that the disorder of some atoms may cause conformation difference for molecules, bring about multiple conformation in crystal state hence reducing the symmetry of molecules in crystal cells. CONCLUSIONS: There can be two or three molecules, even two different compounds in an asymmetrical unit of structure cell because of partial disorder or configuration difference in organic molecule crystals.

Crystallography↗
PubMed1998

Characterization of human TCR Vbeta gene promoter. Role of the dodecamer motif in promoter activity.

During T-lymphocyte development, the T-cell antigen receptor (TCR) gene expression is controlled by its promoter and enhancer elements and regulated in tissue- and development stage-specific manner. To uncover the promoter function and to define positive and negative regulatory elements in TCR gene promoters, the promoter activities from 13 human TCR Vbeta genes were determined by the transient transfection system and luciferase reporter assay. Although most of the TCR Vbeta gene promoters that we tested are inactive by themselves, some promoters were found to be constitutively strong. Among them, Vbeta6.7 is the strongest. 5'-Deletion and fragmentation experiments have narrowed the full promoter activity of Vbeta6.7 to a fragment of 147 base pairs immediately 5' to the transcription initiation site. A decanucleotide motif with the consensus sequence AGTGAYRTCA has been found to be conserved in most TCR Vbeta gene promoters. There are three such decamer motifs in the promoter region of Vbeta6.7, and the contribution of each such motif to the promoter activity has been examined. Further site-directed mutagenesis analyses showed that: 1) when two Ts in the decamer were mutated, the promoter activity was totally abolished; 2) when two additional nucleotides 3' to the end of decamer were mutated, the promoter activity was decreased to two-thirds of the full level; and 3) when the element with the sequence AGTGATGTCACT was inserted into other promoters, the original weak promoters become very strong. Taken together, our data suggest that the positive regulatory element in Vbeta6.7 should be considered a dodecamer rather than a decamer and that it confers strong basal transcriptional activity on TCR Vbeta genes.

Alleles↗
PubMed1998

[Chromosome assignment of a novel microsatellite polymorphic marker (D14S1435) by fluorescence in situ hybridization].

OBJECTIVE: Chromosome assignment of a novel microsatellite marker (D14S1435) containing CA repeats and showing 11 alleles and 0.85 of PIC value in Chinese population) isolated from microdissected human chromosome 14q24.3 DNA library by fluorescence in situ hybridization(FISH). METHODS: The polymorphic marker was used as probe to screen a human Lambda/DASH genome library, a positive clone was isolated and the recombinant phage DNA was extracted as primary material. The insert was recovered through BamH I digestion to complete and low melting point agarose gel electro- phoresis, after processed with Sau3A I the probe was prepared by linker- catch PCR method and the following fluorescence in situ hybridization(FISH) was conducted to metaphase chromosomes. RESULTS: this novel STR was precisely mapped to human chromosome 14q24.3, and this demonstrated the validity of isolating chromosome band-specific genetic markers from probe pool made by chromosome microdissection. CONCLUSION: Confirmed by chromosome fluorescence in situ hybridization, the novel STR obtained by chromosome microdissection, PCR and subcloning method was really from the micro- dissected region. This not only increases the numbers of genetic markers used for linkage analysis in the region,but also provides a novel valuable genetic marker for the gene diagnosis and gene cloning of the possible disease-causing genes located in the region of 14q24.3.

Chromosome Mapping↗
PubMed1998

A stochastic two-phase growth model.

This article proposes a stochastic growth model that starts as a Yule process and is subsequently joined with a Prendiville process when the population attains certain prescribed critical size. In other words, the model assumes a exponential growth in an early stage and logistic growth later on to reflect growth retardation caused by overcrowding. In the case that the population starts with a single unit, closed form expressions are given for the distribution of the population size and for the mean and variance functions of the process. Numerical solutions are briefly discussed for the process that starts with more than one unit.

Animals↗
PubMed1998

Expression, purification, and characterization of recombinant ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit nepsilon-methyltransferase.

Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) large subunit (LS) Nepsilon-methyltransferase (Rubisco LSMT, EC 2.1.1.127) catalyzes methylation of the LS of Rubisco. A pea (Pisum sativum L. cv Laxton's Progress No. 9) Rubisco LSMT cDNA was expressed in Escherichia coli, but most of the expressed protein was found in the insoluble fraction as an inclusion body. Expression at lower temperatures increased the level of soluble Rubisco LSMT and the associated enzymatic activity. However, the soluble form of Rubisco LSMT occurred as two molecular mass forms with the lower molecular mass suggestive of N-terminal processing at Ser-37. Deletion of 108 nucleotides from the 5' end encoding the N-terminal 36 amino acids of Rubisco LSMT resulted in a 10-fold increase in solubility and activity. Further addition of a 3' nucleotide sequence coding for a hexahistidyl carboxy-terminal peptide enabled purification of the N-terminally truncated Rubisco LSMT to homogeneity. Five milligrams of pure recombinant Rubisco LSMT was obtained from a 1-liter E. coli cell culture. The apparent kinetic constants for recombinant Rubisco LSMT for spinach Rubisco and AdoMet were only slightly different from the constants determined using affinity-purified native Rubisco LSMT from pea chloroplasts. However, there was a 6- to 7-fold reduction in the kcat for Rubisco LSMT, which was apparently a consequence of catalytic inactivation due to exposure to NiSO4 during purification. The availability of larger quantities of purified Rubisco LSMT should enable studies of the structure-function relationships in Rubisco LSMT and moreover its interaction with Rubisco.

Amino Acid Sequence↗
PubMed1998

Biodegradation of tricalcium phosphate ceramics by osteoclasts.

Biodegradation of tricalcium phosphate (TCP) ceramics was observed through mixed culture of osteoclasts and TCP discs in vitro in this study. Osteoclasts were isolated from newborn SD rat's marrow of long bone and cultured on TCP discs. The culture terminated at the 48th h and 96th h respectively. Under an inverted microscope, the osteoclasts imparted round or oval body with multinuclear and many thin processes. These cells were positively stained for tartrate-resistance acid phosphatase (TRAP). Scanning electron microscope showed that many resorption lacunae on TCP disc surface and their diameters were smaller than 20 microns. Osteoclasts were located in the lacunae. At the 96th h, the resorption lacunae become larger and osteoclasts showed degeneration. It is suggested that osteoclasts possess ability to re-absorb TCP ceramics under in vitro culturing condition.

Animals↗
PubMed1998

Effects of biliary tract pressure on dynamics of the Oddi's sphincter and its nerve mechanism.

In order to explore the effect of biliary tract pressure on Oddi's sphincter and the mechanism of development of high pressure of biliary tract during acute obstructive and suppurative cholangitis (AOSC), house rabbits were used to establish model of high biliary pressure in acute biliary duct caecus. It was observed that when the pressure of the acute biliary tract was increased to 8 kPa, the electric activity of Oddi's sphincter was obviously enhanced, the pressure of Oddioes sphincter increased remarkably (P < 0.05), and even constant spasm appeared with accompanying increase of discharge frequency of the right greater splanchnic nerves (P < 0.05) and progressive decrease of mean arterial pressure. However, when lidocaine of 0.6% was used to block the right celiac plexus, no above-mentioned reaction happened when the biliary tract pressure was increased again. The results indicated that the acute biliary tract obstruction might induce the contraction or spasm of Oddi's sphincter and bring about a vicious cycle. Its mechanism is related to splanchnic nerves reflection and it is one of important factors in the development of AOSC course.

Acute Disease↗
PubMed1998

The role of vague nerve in the hemodynamic changes induced by acute biliary tract pressure increase.

In order to explore the mechanism of hemodynamic changes caused by high biliary tract pressure, we established an animal model of high biliary tract pressure, in which the disturbance of hemodynamics developed. The cervical or abdominal vague nerve was then blocked. It was observed that when the biliary tract pressure was increased to 16 kPa and kept for 1 h, the arterial blood pressure and cardiac output decreased immediately and parallelly (P < 0.05). When the cervical or abdominal vague nerve were blocked or the pressure of the biliary tract was decreased to zero, both indices returned to normal immediately (P > 0.05). The change of cardiac output lags a little behind that of arterial blood pressure. It suggests that the signal of biliary tract pressure increase can be sent to the cardiovascular center through vague nerve, and the balance between sympathic and parasympathic nerve was broken, which led to the weakening of cardiac contraction and decrease of cardiac output. Due to the peripheral effects of vague nerve, hemodynamic resistance of vessels decreased, which brought about redistribution of peripheral blood flow. Both were the causes of hemodynamic disturbances. After the blood pressure decreased markedly, it showed a jump to normal state when cervical vague nerve was blocked. And the amplitude of diastolic blood pressure restored more than that of systolic blood pressure. This suggests that the cardiac output and peripheral blood resistance are important factors that cause the decrease of blood pressure.

Animals↗
PubMed1998

The bacterial inhibitory ability and in vivo drug release pattern of a new drug delivery system: ciprofloxacine/tricalcium phosphate delivery capsule.

The bacterial inhibitory ability of a new drug delivery system (DDS): Ciprofloxacine/tricalcium phosphate delivery capsule (CTDC), its in vivo drug release pattern, and the influence of ultrasonic irradiation on its drug release were investigated. It was found that CTDC had a strong and sustained inhibitory ability to some common pathogens of bone and joint infections, such as staphylococcus aureus, escherichia coli and pseudomonas aeruginosa. In vivo drug-release study in animals demonstrated a high concentration of ciprofloxacine in the bone tissue surrounding CTDC which was placed in the greater trochanter of the rabbit and continued to release ciprofloxacine for at least 5 weeks and the blood level of ciprofloxacine was low. In vivo study also showed ultrasonic irradiation could increase the amount of ciprofloxacine released from CTDC, which may be an economical, effecient and safe new method to achieve the control of drug release from DDS.

Animals↗
PubMed1998

Ristocetin-mediated interaction of human von Willebrand factor with platelet glycoprotein lb evokes a transient calcium signal: observations with Fura-PE3.

High shear stress in narrowed arteries causes von Willebrand factor (vWf) to bind to its platelet receptor, glycoprotein Ib (GpIb). This binding is reported to promote an increase in intracellular free calcium concentration ((Ca2+)i), which may be responsible for platelet activation. The present study examined the platelet (Ca2+)i signal that arises when ristocetin mediates vWf-GpIb binding. Platelet (Ca2+)i was monitored with Fura-PE3 (Vorndran C, Minta A, Poenie M. Biophys J 1995;69:2112-24), a new ratiometric calcium indicator. Fura-PE3 has calcium-binding characteristics (Kd = 146 nmol/L) and fluorescent properties similar to those of Fura-2. However, its zwitterionic nature ensured much slower extrusion from the platelet (0.2% per minute) than that for Fura-2. This eliminated one of the technical problems that seriously distorted previous measurements of vWf-induced changes in platelets (Ca2+)i. Design of a novel stirring arrangement avoided the other major problem, which is the tendency of platelet aggregates to settle to the bottom of the cuvette, beneath the detection zone of the spectrofluorometer. With Fura-PE3 and the new stirrer used in the present study, vWf-induced changes in (Ca2+)i could be measured reliably in aggregating platelets. Ristocetin-mediated vWf-GpIb binding induced a transient increase in platelet (Ca2+)i. This increase occurred after a significant lag phase; platelet (Ca2+)i rose gradually, followed by a decline to almost the resting level. Binding of vWf to platelet Gplb was responsible for the (Ca2+)i signal. A similar signal was found in the absence of extracellular calcium. These characteristics differ substantially from those described in previous reports, in which the vWf-induced rise in (Ca2+)i was attributed to calcium influx through channels in the plasma membrane. Data from those earlier studies, however, were severely distorted by indicator extrusion and loss of platelet aggregates. The present findings are a more accurate representation of the vWf-induced platelet (Ca2+]i signal.

Adult↗
PubMed1998

Note on the non-homogeneous Prendiville process.

By creating an auxiliary process, this note obtains complete solution to the distribution of the non-homogeneous Prendiville process. In addition, an error in the literature of the original Prendiville process is corrected.

Birth Rate↗