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Biomedical subjects

Q Zou

Publications and source records attributed to Q Zou.

At least 19 recordsLinked to original sources
PubMed2004

Control Issues in High-speed AFM for Biological Applications: Collagen Imaging Example.

This article considers the precision positioning problem associated with high-speed operation of the Atomic Force Microscope (AFM), and presents an inversion-based control approach to achieve precision positioning. Although AFMs have high (nanoscale) spatial resolution, a problem with current AFM systems is that they have low temporal resolution, i.e., AFM imaging is slow. In particular, current AFM imaging cannot be used to provide three-dimensional, time-lapse images of fast processes when imaging relatively-large, soft samples. For instance, current AFM imaging of living cells takes 1-2 minutes (per image frame) - such imaging speeds are too slow to study rapid biological processes that occur in seconds, e.g., to investigate the rapid movement of cells or the fast dehydration and denaturation of collagen. This inability, to rapidly image fast biological processes, motivates our current research to increase the operating speed of the AFM. We apply an inversion-based feedback/feedforward control approach to overcome positioning problems that limit the operating speed of current AFM systems. The efficacy of the method, to achieve high-speed AFM operation, is experimentally evaluated by applying it to image collagen samples.

Journal Article↗
PubMed2003

Quantitative diagnosis of fatty liver with dual-energy CT. An experimental study in rabbits.

OBJECTIVES: To explore the correlation between fatty content of fatty liver and the difference of CT attenuation value in dual-energy CT, and to evaluate the value of dual-energy CT in the quantitative diagnosis of fatty liver in rabbits. MATERIAL AND METHODS: Dual-energy CT at 120 kVp and 90 kVp was performed in 16 rabbits of experimental groups that were induced to various degrees of fatty liver by feeding carbon tetrachloride (CCl4). Four healthy rabbits in the control group underwent dual-energy CT at the same time. The CT attenuation values of liver tissues at 120 kVp (H120), 90 kVp (H90) and the difference (Delta H) between them were obtained. The specimens of liver tissues were examined with freeze section (9 microm) and an oil red O stain histologically. The ratio of fatty content in liver to the liver volume (VP value) was measured using the image analyzer system. RESULTS: The change of CT attenuation values between 120 kVp and 90 kVp was not obvious (Delta H between -0.4 HU and 1.4 HU) in the control group. The density of the liver in the experimental groups decreased differently, and the change in CT attenuation values between high and low energy levels were very clear. H120 values were between 51.0 HU and 91.7 HU and H90 values were between 37.0 HU and 89.2 HU. Delta H values were between 2.5 HU and 14.0 HU. Significant negative linear correlation (r = -0.92, -0.93, t = 8.51, 9.76, p < 0.001, 0.001, respectively) were found between VP values and H120 and H90, respectively, while significant positive linear correlation (r = 0.95, t = 11.89, p < 0.001) was found between VP values and Delta H. CONCLUSION: The amount and degree of fat in the fatty liver can be assessed exactly by dual-energy CT. It will be a potential new effective method for quantitative diagnosis of fatty livers.

Animals↗
PubMed2001

The changes of protein kinase C activity in peripheral blood lymphocytes in the patients with obstructive jaundice and the implication.

The roles of protein kinase C (PKC) signal pathway in the pathogenesis of obstructive jaundice were studied. PKC from cytosolic and membrane fractions of peripheral blood lymphocytes (PBL) in 51 patients with obstructive jaundice and 16 cases of normal controls was isolated and purified. The activities of PKC were determined by radioactive isotope gamma-32P-ATP-catalyzing assay. The results showed that the total PKC activities in PBL in the patients with obstructive jaundice were significantly increased as compared with those in the normal controls (P < 0.01). Moreover, the membrane PKC activities and their percentages of the total PKC activities were higher in obstructive jaundice group than in those in the normal controls (P < 0.05). The total PKC activities in PBL in the patients with obstructive jaundice were significantly positively correlated with the levels of soluble IL-2 receptor (sIL-2R) (r = 0.58, P < 0.01) and the degree of jaundice (T-BIL) (r = 0.67, P < 0.01) in serum. It was concluded that the activities of PKC signal pathway was related with the degree of T-BIL. PKC signal pathway might took part in the activation of T-lymphocytes in the patients with obstructive jaundice and play an important role in the immune regulation and the assessment of pathosis in the patients with obstructive jaundice.

Adult↗
PubMed2001

[Adsorption of anthraquinone dyes by biosorbent GX2].

The GX2 growing mycelium shows excellent adsorptive capacity on the four kinds of anthraquinone dyes, however, due to the difference of molecular structure of dyes, the adsorption rates are different. Although the dyes show inhibiting effect on the growth of GX2, when the concentration of reactive brilliant blue KN-R is 250 and 400 mg/L, the adsorption rate of dye by the GX2 growing mycelium reaches 100% and 91.4%, respectively. With the increase of salinity (NaCl), the dry weight of GX2 mycelium increases; the diameter of granular mycelium decreases and its adsorption surface area increases accordingly, the salinity shows evident enhancement on the adsorption of reactive brilliant blue KN-R by GX2 growing mycelium in the range of 0%-2% salinity. The adsorption process is influenced by the concentration of carbon source as well, reactive brilliant blue KN-R with the concentration of 120 mg/L can be completely adsorbed only when the concentration of glucose is more than 2.5 g/L. The GX2 growing mycelium has better adsorptive capacity than resting living mycelium and dead mycelium.

Adsorption↗
PubMed1999

[A randomized controlled clinical study of sparfloxacin versus ofloxacin in the treatment of bacterial infections].

OBJECTIVE: To evaluate the efficacy and safety of sparfloxacin in the treatment of bacterial infections. METHODS: A randomized controlled multi-centre clinical trial was conducted. Ofloxacin used as the control drug. A total of 212 patients entered the study, with 106 in the sparfloxacin group and the remaining 106 in the ofloxacin group. Both compounds were given by oral administration. RESULTS: The cure rate of sparfloxacin and ofloxacin was 74.5% and 69.8% respectively and the overall efficacy rate was 91.5% and 88.7% respectively. The bacterial clearance rate was 90.7% in the sparfloxacin group and 90.8% in the ofloxacin group. The adverse drug reaction rate of sparfloxacin and ofloxacin was 9.43% and 8.49% respectively. There was no statistical significant difference between the two groups for the above results. The results of in vitro activity of sparfloxacin as compared with other 5 antibacterial agents showed that sparfloxacin had good activity against many Gram-negative organisms and was similar to those of ofloxacin. The activity against Gram-positive organisms (MIC(90) <or= 0.25 mg/L) was generally higher than that of ofloxacin. CONCLUSION: Sparfloxacin is a highly effective and safe broad-spectrum antibacterial agent for the treatment of bacterial infections. It is also effective in the treatment of infections caused by Gram-positive organisms.

Adolescent↗
PubMed1998

Urea effects on protein stability: hydrogen bonding and the hydrophobic effect.

The effects of urea on protein stability have been studied using a model system in which we have determined the energetics of dissolution of a homologous series of cyclic dipeptides into aqueous urea solutions of varying concentration at 25 degrees C using calorimetry. The data support a model in which urea denatures proteins by decreasing the hydrophobic effect and by directly binding to the amide units via hydrogen bonds. The data indicate also that the enthalpy of amide hydrogen bond formation in water is considerably higher than previously estimated. Previous estimates included the contribution of hydrophobic transfer of the alpha-carbon resulting in an overestimate of the binding between urea and the amide unit of the backbone and an underestimate of the binding enthalpy.

Amides↗
PubMed1998

The pharmacokinetics of vecuronium in male and female patients.

UNLABELLED: To evaluate the effect of gender on the pharmacokinetics of vecuronium, we studied 30 patients (15 male and 15 female) undergoing elective plastic surgery with anticipated surgical blood loss of <300 mL under general anesthesia. General anesthesia was induced with thiopental 4-6 mg/kg and fentanyl 2-4 microg/kg and was maintained with 60% nitrous oxide in oxygen and an end-tidal concentration of 1.5%-2% enflurane. After a 2-min infusion of vecuronium 100 microg/kg, a modified fluorometric assay was used to determine the plasma concentrations of vecuronium for 5 h. The results showed that, compared with women, the plasma concentrations of vecuronium in men were significantly lower during the first 20 min and that the disposition kinetics of vecuronium can be best described mathematically by a three-compartment open model in the two groups. The volume of the central compartment and the volume of distribution at steady state were 39.6 +/- 8.6 and 164.8 +/- 29.3 mL/kg, respectively, in women. These values increased significantly to 54.4 +/- 14.4 and 201.4 +/- 75.8 mL/kg in men (P < 0.05). When the data were calculated on the basis of ideal body weight, the volume of distribution of vecuronium was also different between men and women (P < 0.05. The half-lives of fast distribution and distribution, the elimination half-life, mean residual time, area under the plasma-concentration curve, and plasma clearance were not different between the two groups. We conclude that the pharmacokinetics of vecuronium are significantly different between genders and that and men have the greater volume of distribution of vecuronium. IMPLICATIONS: The authors found that, compared with women, men had lower plasma concentrations of vecuronium after the i.v. administration of vecuronium and a larger volume of distribution of vecuronium. The pharmacokinetic differences may be related to the differences in the sensitivity to vecuronium between genders.

Adolescent↗
PubMed1997

Pharmacokinetics of vecuronium during acute isovolaemic haemodilution.

To evaluate the effect of acute isovolaemic haemodilution on the pharmacokinetics of vecuronium, we studied 13 patients undergoing haemodilution during surgery and 13 control patients. General anaesthesia was induced with thiopentone 4-6 mg kg-1 and fentanyl 2-4 micrograms kg-1, and maintained with enflurane and 60% nitrous oxide in oxygen. The haemodilution patients underwent major elective plastic surgery with an anticipated surgical loss of more than 600 ml. Haemodilution was achieved by drainage of venous blood and i.v. infusion of lactated Ringer's solution and 6% dextran, during which the packed cell volume and haemoglobin concentration decreased from 45% to 28.1% and from 14.7 g dl-1 to 9.1 g dl-1, respectively. After administration of a bolus of vecuronium 100 micrograms kg-1, an improved fluorimetric assay was used to measure the plasma concentrations of vecuronium for 5 h. The results showed that the disposition kinetics of vecuronium were best described mathematically by a three-compartment open model in the two groups. The mean volume of the central compartment and volume of distribution at steady state were 42.3 (SD 11.8) ml kg-1 and 168.4 (31.5) ml kg-1, respectively, in control patients, and significantly greater (55.2 (13.4) ml kg-1 and 225.9 (53.3) ml kg-1) in the haemodilution patients (P < 0.05). The elimination half-life was 50.3 (11.5) min in control patients and significantly greater (68.2 (15.1) min) in the haemodilution patients (P < 0.05). The half-lives of fast distribution and distribution, mean residual time, area under the plasma concentration curve and plasma clearance were unchanged in patients who underwent haemodilution compared with the control group.

Adolescent↗
PubMed1997

[Effect of acute moderate isovolumic hemodilution on the pharmacokinetics of vecuronium].

OBJECTIVE: To determine the effect of acute moderate isovolemic hemodilution on pharmacokinetics of vecuronium. METHODS: Twenty-six adult patients, ASA grade I, undergoing elective plastic surgery, were randomly divided equally into the control and hemodilution group. The blood samples were taken for 5 hours following intravenous bolus of 100 micrograms/kg of vecuronium in two groups. The plasma concentrations of vecuronium were determined with an improved fluorometry and the pharmacokinetic parameters were obtained by fitting the data with a 3P87 program. RESULTS: The disposition of vecuronium can be best described by a three compartment open model. As comparison with the control group, the values of Vc and Vdss in hemodilution group were greater than that in the control, while T1/2 beta was markedly prolonged in this group. There were no significant differences in T1/2 phi, T1/2 alpha, K12, K21, K13, K31, K10, MRT, AUC, and Cl between the two groups. CONCLUSION: Acute moderate isovolemic hemodilution could change the pharmacokinetics of vecurinium, particularly in distribution and elimination phases.

Adolescent↗
PubMed1996

Effects of enflurane and isoflurane anesthesia on the pharmacokinetics of pancuronium in adult patients.

OBJECTIVE: To evaluate the effects of 1 MAC of enflurane or isoflurane anesthesia on the pharmacokinetics of pancuronium. METHODS: Eighteen adult patients undergoing the elective plastic surgery were randomly divided equally into 3 groups, namely, Group 1 (control group), Group 2 (enflurane group) and Group 3 (isoflurane group). Anesthesia was maintained with thiopental and 67% N2O-O2 in Group 1, 1 MAC enflurane in Group 2 and 1 MAC isoflurane in Group 3. After administration of a bolus of pancuronium 100 micrograms/kg, an improved fluorimetric assay was used to determine the serum concentrations of pancuronium and the pharmacokinetic variables of pancuronium were calculated with a 3P87 program. RESULTS: The disposition of pancuronium may be well described mathematically by a two-compartment open model. The results showed that in comparison with the control group, patients in Group 2 and Group 3 had a longer T1/2 beta and MRT. The patients in Group 2 had the slower K10 and lower CL than those in the control group. There were no significant differences among the three groups in T1/2 alpha, V1, V2, Vdss, V beta, K21, K12 and AUC. CONCLUSION: During enflurane and isoflurane anesthesia, CL of pancuronium decreased, and T1/2 beta and MRT of pancuronium were prolonged in our patients, so duration of the effective plasma concentrations of pancuronium was much longer. As a result, the effects of enflurane and isoflurane of the pharmacokinetics of pancuronium may be part of reason why two drugs extended the duration of neuromuscular depression produced by pancuronium.

Adolescent↗
PubMed1996

[The pharmacokinetics of pancuronium bromide in infants, children and adults].

Twenty-four patients scheduled for elective plastic surgery were selected to study the pharmacokinetics of pancuronium bromide under enflurane anesthesia. The patients were divided into three groups by their ages; Group 1 consisted of 5 infants (0.75-2.95 years); Group 2 contained 13 children (4-14 years); Group 3 included 6 adults (16-27 years). An improved fluorimetric assay was used to measure the plasma concentrations of pancuronium bromide after administration of pancuronium bromide at a dose of 100 micrograms/kg. The results showed that the disposition of pancuronium bromide may be best described mathematically by a two-compartment open model in all patients. The younger the patients, the larger the distribution volumes and the higher the Cl. There were significant differences among the three groups with regard to V1, V2, Vdss, Cl, AUC. The T1/2 beta and MRT were longer in Group 1 than in Group 2 and Group 3.

Adolescent↗
PubMed1996

[Characteristics and treatment of Staphylococcus aureus endocarditis].

In order to evaluate whether there were changes of the clinical features of Staphylococcus (Staph.) aureus endocarditis in recent years, the data of 21 cases of Staph. aureus endocarditis diagnosed from 1977 to 1994 were analyzed and compared with those of 11 cases of Staph. aureus endocarditis from 1957 to 1977. The results showed the following changes in recent years. The incidence of Staph. aureus endocarditis cases has been increasing. Cases of right-sided endocarditis increased in the recent two decades and this increase was related to intravenous drug abuse and increased use of vascular intervention. Right-sided endocarditis was different from left-sided endocarditis in their risk factors, underlying heart diseases, clinical manifestations and prognosis. The clinical manifestations of ventricular-wall endocarditis were atypical and it could be definitely diagnosed only with echocardiogram. Complications of Staph. aureus endocarditis became more common and serious, in recent decades but hospital mortality decreased markedly due to effective antibiotic management. The authors believe that sound knowledge of Staph. aureus endocarditis is essential for the proper diagnosis and treatment of Staph. aureus endocarditis.

Adolescent↗
PubMed1995

[G gamma/A gamma, A gamma I/A gamma T ratios of fetal hemoglobin of Han, Hui, Uygur and Kazak newborns in Xinjiang and gene mapping analysis of two cases with abnormal ratio].

The G gamma/A gamma, A gamma I/A gamma T ratios of fetal hemoglobin of 372 cord blood samples of newborns (Han 102, Hui 102, Uygur 99, and Kazak 69) in Urumchi were determined by HPLC. The means of G gamma ratios of 4 ethnic groups (Han, Hui, Uygur, and Kazak) were 66.83%, 68.33%, 70.44% and 69.70%, respectively. 4 cases (Hui 3 and Kazak 1) with low G gamma (< 50%), and 25 cases (Han 5, Hui 4, Uygur 11 and Kazak 5) with high G gamma (> 80%) were found. The occurrences of low G gamma in Hui and Kazak were 2.94% and 1.45% while in Han and Uygur no single case with low G gamma was found. Those of high G gamma in 4 ethnic groups were 4.9% (Han), 3.9% (Hui), 11.1% (Uygur) and 7.2% (Kazak), respectively. A gamma T heterozygotes in Han 21, Hui 23, Uygur 26 and Kazak 29 cases, and one A gamma T homozygote in each ethnic group were found. The average values of A gamma I were 56.83%, 55.58%, 50.94% and 54.68% respectively. The frequencies of A gamma T gene were 0.113, 0.123, 0.141 and 0.225, respectively. The gene arrangement of a low G gamma case was identified as-GA gamma I-/-G gamma-A gamma I-, and that of a high G gamma case as -G gamma-AG gamma-A gamma I(A gamma T)-/-G gamma-A gamma T(A gamma I)-.

China↗
PubMed1994

High-level expression of staphylococcal nuclease A in Escherichia coli.

The staphylococcal nuclease A gene has been successfully cloned and overexpressed in E. coli under the transcriptional control of the bacteriophage lambda PRPL promoters regulated by the temperature sensitive repressors. The SDS-PAGE analysis demonstrates that the nuclease A is produced to the extent of as much as 60% of the total cellular protein. The N-terminal analysis of the nuclease A shows that the amino terminal formyl methionine residue of the enzyme is precisely processed. The recombinant nuclease A with full activity is finally obtained after appropriate solubilization--denaturation and renaturation treatment. The conformational identity of the renatured nuclease A in different conditions is also studied by using hydrophobic interaction chromatography on a phenyl-superose HR5/5 column.

Base Sequence↗
PubMed1993

On nonaxisymmetric entry flow at very low Reynolds numbers.

The eigensolution of nonaxisymmetric entry flow of a Newtonian viscous fluid with very small Reynolds number in a semiinfinite rigid circular pipe is obtained. Leading eigenvalues are computed for steady flow and two periodic cases. The result shows that the entry length for nonaxisymmetric flows should be longer than the entry length for axisymmetric flows.

Animals↗
PubMed1992

High-level expression of staphylococcal nuclease R gene in Escherichia coli.

Staphylococcal nuclease R, an analogue of nuclease A, was overproduced under the transcriptional control of the bacteriophage lambda PRPL promoters regulated by temperature sensitive repressors. The expression level reached 200-300 mg l-1 and showed little host dependence in different strains. The investigations of the recombinant nuclease R have revealed that the amino terminal formyl methionine residue of the nuclease is precisely processed, the protein consists of 155 amino acid residues. The experiment shows that the pBV221-DH5 alpha is a quite suitable vector-host system for high-level expression and precise processing of heterologous genes in Escherichia coli. The comparative studies between the codons used in the staphylococcal nuclease R gene and the optimal codon usage in E. coli indicate that high level expression of heterologous genes in E. coli may not always require a high degree of codon usage bias.

Amino Acid Sequence↗
PubMed1991

Nonaxisymmetric wave propagation through a viscous fluid in a viscoelastic tube.

The eigensolution of a nonaxisymmetric linear wave propagation through a viscous fluid in a viscoelastic pipe is obtained. The solution can serve as a foundation for studying nonaxisymmetric blood flow. Some leading eigenvalues for two special cases are computed. The result shows that nonaxisymmetric modes decay fast during their propagation.

Animals↗