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Biomedical subjects

G Q Zhang

Publications and source records attributed to G Q Zhang.

At least 19 recordsLinked to original sources
PubMed2006

Clinical and pathologic changes in a guinea pig aerosol challenge model of acute Q fever.

Acute Q fever is a zoonotic disease caused by the obligate intracellular bacterium Coxiella burnetii and can manifest as a flu-like illness, pneumonia, or hepatitis. A need exists in Q fever research for animal models mimicking both the typical route of infection (inhalation) and the clinical illness seen in human cases of Q fever. A guinea pig aerosol challenge model was developed using C. burnetii Nine Mile phase I (RSA 493), administered using a specialized chamber designed to deliver droplet nuclei directly to the alveolar spaces. Guinea pigs were given 10(1) to 10(6) organisms and evaluated for 28 days postinfection. Clinical signs included fever, weight loss, respiratory difficulty, and death, with the degree and duration of response corresponding to the dose of organism delivered. Histopathologic evaluation of the lungs of animals infected with a high dose showed coalescing panleukocytic bronchointerstitial pneumonia at 7 days postinfection that resolved to multifocal lymphohistiocytic interstitial pneumonia by 28 days. Guinea pigs receiving a killed whole-cell vaccine prior to challenge with the highest dose of C. burnetii were protected against lethal infection and did not develop fever. Clinical signs and pathological changes noted for these guinea pigs were comparable to those seen in human acute Q fever, making this an accurate and valuable animal model of human disease.

Acute Disease↗
PubMed2003

Prediction of early recurrence of atrial fibrillation after external cardioversion by means of P wave signal-averaged electrocardiogram.

BACKGROUND: Therapy of atrial fibrillation by electrical cardioversion (CV) is limited by the high rate of recurrences. Early recurrence of atrial fibrillation (ERAF) occurs in a subgroup of patients whose characteristics are poorly defined. This prospective study was performed to evaluate if the P wave signal-averaged ECG (PSAECG) is able to identify patients with an increased risk of ERAF after CV. METHODS: Patients with an indication for elective external CV were enrolled. After successful CV, PSAECGs were recorded at 0.5, 1, 24 h and 1 week. The ability of PSAECG parameters (signal-averaged P wave duration, PWD; root-mean-square of the voltage of the terminal 20, 30, and 40 ms of the signal-averaged P wave; RMS20, RMS30, RMS40) to predict ERAF (prospectively defined as AF recurrence within 4 h after CV) was assessed. RESULTS: Of 111 consecutive patients, 7 experienced ERAF, 30 patients had AF recurrence later during the 1-week follow-up. Patients with ERAF had a significantly prolonged signal-averaged PWD compared to patients who remained in SR (194+/-16 ms vs 139+/-3 ms at 0.5 h, p<0.001). As ROC analysis revealed, a PWD >/=154 ms at 30 min after CV had the highest predictive accuracy for ERAF (sensitivity 100%, specificity 82%, positive predictive value 33%, negative predictive value 100%). Other parameters of the PSAECG did not reveal significant differences between patients with and without ERAF. CONCLUSIONS: The PSAECG provides a sensitive noninvasive tool for detection of patients at risk of ERAF. Thus identified, tailored pharmacological therapy is conceivable to prevent ERAF.

Aged↗
PubMed2003

Identification and cloning potentially protective antigens of Coxiella burnetii using sera from mice experimentally infected with Nine Mile phase I.

Coxiella burnetii is an obligate intracellular bacterium that causes acute Q fever and occasional chronic infections in humans. To determine the immunodominant antigens during infection with C. burnetii, sera from mice experimentally infected with Nine Mile phase I were tested by immunoblotting. The mouse sera recognized antigens with a variety of molecular weights, including proteins of 14, 22, 28, 34, and 60 kDa as immunodominant antigens. In order to clone potential protective antigens, a genomic DNA library of Nine Mile phase I was constructed in the expression vector Lambda ZAP Express and screened with sera from mice that recovered from C. burnetii infection. A total of 102 immunoreactive clones with various signal intensities were identified from about 8,000 plaques. These clones were purified and expressed in the excised plasmid pBK-CMV. The proteins expressed by these recombinant plasmids were analyzed by SDS-PAGE and immunoblotting. Fifty-four clones expressed immunoreactive proteins of molecular masses ranging from approximately 14 to 60 kDa. Sequence analysis and BLAST search of the recently completed genome sequence identified a variety of novel immunoreactive proteins. These proteins are logical vaccine candidates for testing protective activity against C. burnetii challenge. We established a sublethal challenge model in BALB/c mice with protection from the development of severe splenomegaly as an indicator of vaccinogenic activity. Further characterization of these proteins will provide essential information for developing novel, specific diagnostic reagents and potential subunit vaccine candidates against C. burnetii infection.

Animals↗
PubMed2001

Groin hernias in adults: value of color Doppler sonography in their classification.

PURPOSE: We assessed the abilities of color Doppler and power Doppler sonography to distinguish among types of groin hernias by demonstrating the inferior epigastric artery (IEA) and its relationship with the hernia sac. METHODS: Nineteen consecutive patients (14 men and 5 women), clinically diagnosed as having groin hernias and scheduled to undergo herniorrhaphy, were prospectively enrolled in this study. Ultrasound examinations were performed preoperatively with a 6-12-MHz linear-array transducer. The IEA was identified, if possible, and its relationship to the hernia sac assessed. The sonographic diagnoses were compared with the operative findings. RESULTS: There were 15 indirect inguinal hernias, 4 direct inguinal hernias, and 1 femoral hernia; 1 patient had bilateral inguinal hernias (indirect and direct). In 18 (90%) of 20 hernia cases, the trunk segment of the IEA could be visualized. In 11 (55%) of 20 hernia cases, the origin segment of the IEA could be visualized and its relationship with the hernia sac assessed. In 9 (82%) of the 11 hernia cases, hernia types were correctly diagnosed by sonography. The overall accuracy of sonography for diagnosing the type of hernia was 45% (9 of 20 hernias). CONCLUSIONS: Color Doppler sonography can accurately differentiate types of groin hernias if the origin segment of the IEA and the hernia sac can be visualized simultaneously. However, color Doppler sonography sometimes failed to visualize this segment.

Adult↗
PubMed2001

[P-wave signal averaging-ECG: normal values and reproducibility].

Signal averaging techniques are used for detection of low amplitude, high frequency signals in the surface ECG. P-wave signal-averaging has been used to predict the risk for development of atrial tachyarrhythmias in patients with structural heart disease. There is, however, a lack of prospective studies evaluating normal values of the P-wave signal-averaged ECG in healthy individuals. Moreover, day-to-day reproducibility of results of P-wave signal-averaging is not precisely known. Thus, the aim of this study was to determine normal values and reproducibility of time-domain P-wave signal-averaging in a large cohort of healthy volunteers. A commercially available device (MAC 5000, Marquette Hellige) was used for signal-averaging. A vector magnitude was calculated from Frank's orthogonal leads after P-waves were sampled and filtered with a spectral filter using fast fourier transform. We examined 123 volunteers without cardiovascular disease at two occasions. Mean P-wave duration was 114 +/- 13 ms for the overall study population. There was a slight but statistically significant increase in filtered P-wave duration with age (r = 0.32, p < 0.001). All values were reliably reproducible upon the second examination (r = 0.624 to 0.706, p < 0.0001). These results may serve as a future reference to other studies examining patients with structural heart disease.

Adult↗
PubMed2001

Effect of tetramethyl pyrazine on L-type calcium channel in rat ventricular myocytes.

To elucidate possible ionic mechanisms of antimyocardial ischemia and antiarrythmia of tetramethyl pyrazine (TP), we studied L-type Ca2+ currents (I(Ca.L)) in adult rat ventricular myocytes using the whole-cell patch-clamp technique. The results showed: (i) under physiological conditions, 0.25 mmol/L TP decreased amplitude of I(Ca.L) to 60.6% and this inhibition was increased with increasing concentration of TP. ID50 was 0.20 mmol/L. (ii) The Ca2+-antagonistic effect of TP was voltage-dependent. A marked negative shift of the steady-state inactivation curve was observed with long (10 s) conditioning prepulses, but not with short (350 ms) ones. (iii) The time course of inhibition during TP treatment was increased with an increase in drug concentration, and recovery from TP-induced inactivation of I(Ca.L) was slower than in control cases. (iv) Tonic block and use-dependent block with TP treatment, which was induced by increasing the frequency of stimulation, occurred. We suggest that TP inhibits the I(Ca.L) mainly by binding to inactivated Ca2+ channels. The high affinity of TP for the inactivated state of I(Ca.L) may play an important role in developing therapies for pathological conditions.

Animals↗
PubMed2001

Puerarin blocks transient outward K+ current and delayed rectifier K+ current in mice hippocampal CA1 neurons.

AIM: To study the effects of puerarin (Pue) on IA and IK in mouse hippocampal neurons. METHODS: The whole cell patch clamp techniques were used. RESULTS: Pue reduced the amplitude of IA and IK, in a concentration-dependent, but not rate- or use-dependent manner (IC50 were 461 micromol/L and 215 micromol/L, respectively). Pue (0.5 mmol/L) shifted the steady state activation curves of IA and IK to positive and negative potentials (Vh about 20.6 mV and 28.6 mV) respectively, but inactivation curves of IA were not affected by Pue. CONCLUSION: Pue inhibited IA and IK in mouse hippocampal CA1 neurons and its blocking effect on I(K) was much stronger than on IA.

Animals↗
PubMed2001

[Separation and determination of pseudoephedrine in bufferin cold tablet by capillary electrophoresis with hydropropyl-beta-cyclodextrin as chiral selective reagent].

A method for the separation and analysis of the chiral pseudoephedrine enantiomers using capillary electrophoresis was established. The buffer solution for separation was 25 mmol/L Tris-phosphate, including 38 mmol/L hydropropyl-beta-cyclodextrin with pH value of 2.65. (1S, 2S)(+) Pseudoephedrine in Bufferin Cold tablet was determined. The method has good precision, recovery and linear relationship.

2-Hydroxypropyl-beta-cyclodextrin↗
PubMed2001

[Bepridil inhibition on the delayed rectifier K+ currents in thyroxine induced hypertrophied guinea pig ventricular myocytes].

AIM: To study the effects of bepridil on the rapidly activating component (IKr), the slowly activating component (IKs) of the delayed rectifier potassium current and the inward rectifier potassium current (IK1) in hypertrophied guinea pig ventricular myocytes. METHODS: The whole cell patch clamp techniques were used. RESULTS: In hypertrophied guinea pig ventricular myocytes, bepridil 30 mumol.L-1 markedly inhibited IKr and IKs (by 20.9% and 27.2% at 0 mV and mV, respectively). The effect of bepridil on IKs was larger than on IKr. Bepridil 30 mumol.L-1 also significantly inhibited the inward component of IK1 (by 15.1% at +100 mV), but the reverse potential of IK1 was unaffected. Bepridil (1-100 mumol.L-1) was shown to inhibit IKr and IKs in a concentration-dependent manner. Their IC50 were 46.7 mumol.L-1 and 23.8 mumol.L-1, respectively. CONCLUSION: Bepridil inhibit IKr, IKs and IK1 in hypertrophied guinea pig ventricular myocytes, which may be important in understanding the antiarrhythmic effects of this drug.

Animals↗
PubMed1999

Determination of glycyrrhizin in radix glycyrrhizae and its preparations by capillary zone electrophoresis.

A capillary zone electrophoresis method was set up for the separation and determination of glycyrrhizin in Chinese medicinal preparations. Concentrations of Na(2)B(4)O(7) were optimized, which showed that glycyrrhizin in the sample could be separated from interference in the running buffer of 30 mmol/L Na(2)B(4)O(7). Using declofenac as internal standard, the simple method was linear in the range 25-300 microg/mL of glycyrrhizin, and good reproducibility was obtained. The extracts of Radix glycyrrhizae and its preparations could be injected directly for analysis without any pretreatment.

Animals↗
PubMed1999

Determination of berberine in Rhizoma coptidis and its preparations by non-aqueous capillary electrophoresis.

A non-aqueous capillary electrophoretic method was established for the determination of berberine in Rhizoma coptidis and its preparations. The effects of organic solvent and the concentrations of sodium acetate were studied, which showed that berberine in extracts of traditional Chinese medicine can be separated successfully in a buffer solution of 75 mmol/L of sodium acetate in methanol containing 1 mol/L of acetic acid. The simple and rapid method was linear in the range 25-200 microgram/mL of berberine and had a good reproducibility, with the relative standard deviation below 2%. Non-aqueous capillary electrophoresis is a satisfactory system for the analysis of alkaloids in traditional Chinese medicine.

Anti-Infective Agents, Local↗
PubMed1999

Chronic levothyroxin treatment is associated with ion channel abnormalities in cardiac and neuronal cells.

1. We investigated the ion currents responsible for repolarization of guinea-pig isolated myocytes (ICa) and rat hippocampal CA1 neurons (IA and IK) by means of the whole-cell holding technique. 2. The rat hypertrophied heart, induced by levothyroxin, caused exaggerated cardiac arrhythmias after coronary ischaemia-reperfusion. 3. We found an enhanced ICa in guinea-pig isolated myocytes and decreased IA and IK in rat hippocampal CA1 neurons following levothyroxin treatment. Blockade of the outward K+ current and an increment in inward Ca2+ current by chronic levothyroxin treatment contributed to the delayed repolarization and aggravated cardiac arrhythmias. 4. Animals treated with chronic levothyroxin may serve as pathological models for the investigation of the pattern of ion channel disorders with regard to impaired repolarization and aggravated cardiac arrhythmias.

Animals↗
PubMed1999

[Molecular mapping of the S-a locus for F1 pollen sterility in cultivated rice (Oryza sativa L.)].

F1 pollen sterility in cultivated rice (Oryza sativa L.) was found to be caused by at least six loci of F1 pollen sterility genes. At the S-a locus, one of the six loci for F1 pollen sterility, the allelic interaction of S-ai and S-aj causes the male gametes carrying S-aj allele abortive. To map the S-a locus, Taichung 65(T65), a Keng (japonica) variety with S-aj/S-aj, its isogenic F1 sterile line TISL4 with S-ai/S-ai from Chin-tsao, a Hsien (indica) variety, and the F2 population from cross T65 x TISL4 were used as materials. The polymorphism between T65 and TISL4 detected by RFLP and RAPD analysis was less than 1%. This result indicated that short segments from Chin-tsao were introgressed into the isogenic F1 sterile line, since the TISL4 was developed by repeatedly backcrossing for thirteen times. By linkage analysis of S-a and the marker loci, the S-a locus was mapped on chromosome 1. The genetic distances between S-a and RFLP markers CDO548 and RG146 are 6.4 cM and 7.2 cM respectively, and those between S-a and RAPD markers O11-1000 and Y13-500 are 6.8 cM and 11.2 cM respectively. The mapping of the S-a locus is an important step towards marker-aided selection for overcoming the hybrid sterility in rice.

Chromosome Mapping↗
PubMed1998

Antigenic characteristics of polypeptides of Coxiella burnetii isolates.

Eighteen Coxiella burnetii strains from a variety of clinical and geographical sources were screened for antigenic variation of polypeptides by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) coupled with Coomassie brilliant blue (CBB) staining or immunoblotting. These polypeptide profiles showed the greatest variability in the region from 33 to 8.1 kDa. Such differences in the antigenicity of the polypeptides were also recognized by immunoblotting with 15 various mouse anti-C. burnetii antisera. In addition, we detected a polypeptide at about 28 kDa which was immunodominant in strains from human cases of acute Q fever, milk and ticks but not immunogenic in strains from human cases of chronic Q fever. These findings suggest that this polypeptide is a marker to distinguish between acute and chronic strains.

Animals↗
PubMed1998

Evaluation of a recombinant 27-kDa outer membrane protein of Coxiella burnetii as an immunodiagnostic reagent.

The 27-kDa outer membrane protein from eight strains of Coxiella burnetii was expressed in the pET-21c protein expression system. Two fusion proteins with molecular masses of 30 and 32 kDa were evident in all eight of the recombinants by SDS-PAGE and immunoblotting. A protein having an approximate size of 30 kDa was purified from the Escherichia coli lysates by one-step affinity purification. The utility of the purified recombinant protein in ELISA was also evaluated by testing its reactivity with human sera and comparing this reactivity with that of Nine Mile phase II antigen. All of the 40 IF-positive serum samples were ELISA-positive for both the Nine Mile phase II and recombinant antigens, and negative serum controls were negative for both antigens. These results suggest that ELISA with the 27-kDa recombinant antigen is a sensitive and specific method for detecting anti-C. burnetii antibodies in human sera.

Animals↗