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Biomedical subjects

S Gao

Publications and source records attributed to S Gao.

At least 199 records · Page 11Linked to original sources
PubMed1993

[Column switching HPLC method for determination of dextrorphan, an active metabolite of dextromethorphan, in plasma].

An HPLC method for the determination of dextrorphan, an active metabolite of dextromethorphan, in plasma was established using column switching technique. The column switching system was equipped with a per-column of 30 mm x 5 mm ID, packed with mu Bondapak C18, 37-50 microns, and an analytical column of 150 mm x 5 mm ID, packed with YWG-C18, 5 microns. A 0.2% acetic acid solution was used as the pretreating mobile phase to wash out impurities from the per-column. The analytical mobile phase consisted of acetonitrile-water-acetic acid-triethylamine-dichloromethane (17:82:1:0.05:0.025). The plasma samples were directly injected into the HPLC system after enzymatic hydrolysis of dextrorphan glucuronide ester conjugate to free form with beta-glucuronidase. The dextrorphan was monitored with a fluorescence detector at 290 nm (excitation) and 315 nm (emission). The method was linear within the plasma concentration range of 20-640 ng/ml (r = 0.9987), and the detection limit was 4 ng/ml. The mean recoveries of the method averaged 103.8%. The relative standard deviations of the assay were less than 10% for both within-day and between-days.

Chromatography, High Pressure Liquid↗
PubMed1993

[Pharmacokinetics and pharmacodynamics of two morphologically homogenous forms of famotidine per os in Chinese healthy volunteers].

The lg C of famotidine (Fam) A and B forms in plasma vs time curve following a single oral dose of 40 mg showed an one-compartment open model in 5 healthy volunteers. The T1/2Ke of Fam A and B forms = 3.06 and 3.48 h, Tmax = 2.96 and 2.68 h, The Cmax = 115 and 145 ng.ml-1, AUC = 811 and 1190 h.ng.ml-1, respectively. No significant difference was found in the pharmacokinetic and pharmacodynamic properties between Fam A and B forms. The mathematical model describing the whole course of blood concentration of Fam A and B forms in relation to inhibiting effects on gastric acid were: E (A) = 100.C2.04/(C2.04 + 15.0(2.04)) and E (B) = 100.C1.67/(C1.67 + 14.0(1.67)). Predication of blood drug concentration from pharmacodynamics or vice versa became possible using the mathematical equations.

Administration, Oral↗
PubMed1993

[Determination of cefixime in human plasma and urine using high performance liquid chromatography column switching technique].

A double column and double pump HPLC switching system is described for the analysis of cefixime in human plasma and urine. The system used muBondapak C18 short pretreatment column for on-line sample clean-up and a Hitachi GEL 3056 (ODS) analytical column for separation. A mixed solution of 0.01 mol/L H3PO4-0.1 mol/L KH2PO4-H2O (20:1:79) was used as the pretreatment mobile phase and CH2CH-0.01 mol/L H3PO4-0.1 mol/L KH2PO4-H2O (13:20:1:66) was used as analytical mobile phase. The compound in plasma and urine is detected by ultraviolet absorption at 286 nm and 314 nm, respectively. The absolute recoveries of the method in plasma and urine were 99.1% and 98.6% respectively. The relative standard deviations of the method are 0.70-3.82% and 0.80-3.73% in plasma, 1.53-3.08% and 1.31-2.67% in urine between days and day-to-day. Linear calibration curve for cefixime was measured over the range of 0.1-3.2 micrograms/ml in plasma and 1.0-32.0 micrograms/ml in urine, and the correlation coefficients were all 0.9999. The detection limit was 0.05 micrograms/ml in plasma and 0.2 micrograms/ml in urine. The plasma and urine samples were diluted with water and injected directly onto the HPLC system. The operation is simple and the relative sensitivity is markedly increased because of higher recoveries and larger loading capacity of the sample.

Cefixime↗
PubMed1992

Simple high-performance liquid chromatographic method for the determination of captopril in biological fluids.

A rapid, simple and sensitive column-switching high-performance liquid chromatographic procedure for the determination of captopril in plasma and urine had been developed. p-Bromophenacyl bromide was used as a derivatizing reagent to react with captopril to form a product that showed ultraviolet-absorbing properties. For plasma samples the protein was removed with 6% perchloric acid before injection. The urine samples were directly injected into the chromatograph. The column-switching system was equipped with a pre-column (5 cm x 0.5 cm I.D.) packed with muBondapak C18 (37-50 microns) and an analytical column (15 cm x 0.5 cm I.D.) packed with YWG-C18, 10 microns. Impurities were washed from the pre-column with 0.2% acetic acid and the retained substances were eluted into the analytical column with acetonitrile-water-acetic acid (35:65:0.4, v/v). Captopril was detected at 260 nm. The calibration curve was linear in the range 20-1000 ng/ml for plasma and 10-200 micrograms/ml for urine. The recoveries averaged 103.2 and 99.5% for plasma and urine, respectively. The coefficients of variation were all less than 10%.

Captopril↗
PubMed1992

[Cell morphometric analysis in oral submucous fibrosis, leukoplakia and squamous cell carcinoma].

The morphometry of the cells and the nuclei in the spinous cells of oral epithelium in 48 specimens were studied by interactive image analysis system (IBAS-II). Five groups, normal mucosa, oral submucous fibrosis (OSF), leukoplakia, epithelial dysplasia and squamous cell carcinoma, were included. The result showed a progressive reduction in the dimensions (area, perimeter, all kinds of diameter) of the cells from normal mucosa, through OSF, leukoplakia, dysplasia to carcinoma (P < 0.01), while the dimensions of the nuclei did not show significant differences among the groups (P > 0.05), except the minimum diameter, but the nuclear cytoplasmic ratio showed a progressive increase (P < 0.01). The shape factors (form factor [PE] and contour index [CI]) seemed to be less helpful in identification. It indicated that the decrease of cell area of the spinous cell could reflect a malignant progress, and nuclear cytoplasmic ratio might be an objective feature to distinguish carcinoma from other lesions. The result also suggested that the pathological grade of OSF is between normal mucosa and mild epithelial dysplasia.

Carcinoma, Squamous Cell↗
PubMed1992

[Absorption of ceftizoxime from peritoneal dialysate and its pharmacokinetics in chronic kidney failure patients].

The pharmacokinetics of ceftizoxime (Cef) and its diffusivity across the peritoneal membrane were studied in 10 chronic kidney failure patients undergoing continuous ambulatory peritoneal dialysis. Cef was determined by HPLC. The results showed that the disposition of Cef could be described with a 2-compartment open model after 1 g intravenous infusion. VD = 20 +/- 5 L, AUC = 1237 +/- 327 micrograms.ml-1.h. T1/2 beta = 16.9 +/- 4.5 h, which was much longer than that of patients with normal renal function. Therefore, the regulation of dose regimen was necessary when treating patients with renal failure. Cef was partly eliminated by peritoneal dialysis with the ClD of 2.9 +/- 1.0 ml.min-1. The bidirectional exchange of Cef was seen between blood and dialysate. It is more suitable to describe the diffusive characteristics of Cef from dialysate (or blood) into blood (or dialysate) with a zero order constant rate model. The absorption percentage of Cef after 0.5 g instilled with peritoneal dialysate was 90.4 +/- 7.0%.

Absorption↗
PubMed1992

[Determination of captopril in plasma and urine by high-performance liquid chromatography with column switching].

A rapid and sensitive column-switching high performance liquid chromatographic procedures was described for determination of captopril in plasma and urine. p-Bromophenacyl bromide, a derivatizing reagent, was added to the plasma and urine samples to form an adduct which showed ultraviolet absorbing properties. After that, the urine sample was injected directly and for plasma the protein was removed with 6% of perchloride before injection. The column-switching system was equipped with a pre-column of 5 cm x 0.5 cm ID, packed with mu Boundapak C18, 37-50 microns, and an analytical column of 15 cm x 0.5 cm ID, packed with YWG-C18, 10 microns. After washing out the impures from pre-column with 0.2% acetic acid the retained substances were eluted into analytical column with acetonitrile-water-acetic acid (35:65:0.4). Captopril was detected at 260 nm. The method was linear within 20-1000 ng/ml for plasma and 10-200 micrograms/ml for urine. The recovery averaged 103.2% and 99.5% for plasma and urine, respectively. The coefficient variations were all less than 10%.

Captopril↗
PubMed1991

Pharmacokinetics and bioavailability of famotidine in 10 Chinese healthy volunteers.

The pharmacokinetics and bioavailability of famotidine were investigated by HPLC method in 10 Chinese healthy volunteers. Data obtained from HPLC were analysed automatically using a MCPKP program on microcomputer. Linear pharmacokinetics were observed following either iv or po administration. After 20 mg iv, plasma levels declined biexponentially with an initial T1/2 of 0.3 +/- 0.2 h and terminal T1/2 of 3.5 +/- 0.8 h. The plasma elimination T1/2 following po administration were 3.4 +/- 0.7 h and 3.5 +/- 0.5 h for capsules and tablets respectively. Oral absorption was incomplete. The absolute bioavailabilities were 38 +/- 10% for capsules and 43 +/- 11% for tablets. Renal excretion was the major route of elimination. About 72% of the dose were recovered as unchanged famotidine in urine. Mean renal and plasma clearance were 416 and 541 ml.min-1 respectively.

Adult↗
PubMed1990

Pulmonary artery involvement in aorto-arteritis. An analysis of DSA.

Angiographic features of the pulmonary artery were studied in 24 patients with aortoarteritis (Takayasu's arteritis) by digital subtraction angiography. The pulmonary artery involvement was found in nine cases (37.5%). The right side was involved in eight and the left side in five cases. The right pulmonary artery was involved in two cases, the lobar artery in six, the segmental artery in six, and subsegmental as well as peripheral branches in four. The angiographic features were stenosis and/or occlusion as were the changes of the systemic arteries in aorto-arteritis. The aorta and its main branches were involved in all nine patients, but the severity of pulmonary vascular changes was not always related to the systemic vascular changes. Bronchial angiography demonstrated enlarged and tortuous bronchial arteries in four cases. Lung ECT revealed abnormalities in four cases.

Adolescent↗
PubMed1990

[Study on the discrimination of bacteria by gas chromatographic profiles of cellular monosaccharides].

A procedure for obtaining gas chromatographic (GC) profiles of bacterial cellular monosaccharides was described. Some of the unknown component peaks in these profiles were identified. And, based on the complete linkage cluster analysis with the Euclidean distance coefficient, the interpretation of the resulting cellular monosaccharides of bacteria were performed by mini-computer. By means of this method, the discrimination of 5 species (24 strains) of aerobic endospore-forming bacteria. The results showed that there were defined differences between the profiles of cellular monosaccharides of B. anthracis and B. cereus. This procedure has provided a useful method for the classification and identification of microorganisms, for their physiological and biochemical studies, and for studies on their subcellular components.

Bacillus↗
PubMed1990

[Clinical and experimental study of wei-nin granules in the treatment of chronic superficial gastritis].

408 cases of chronic superficial gastritis diagnosed by fibergastroscopy and histology were treated with Wei-Nin granules (WNG), The symptomatic effective rate was 90.5%, while therapeutic effect proved by gastroscopy and histology was 81.9% and 72.8% respectively. These results compared with the control were statistically significant. In animal experiment, it is shown that WNG had an evident protective effect to the mucous membrane of rats and guinea pigs. These animals had suffered gastritis and gastric ulcer induced by drugs. The effect of WNG was similar to cimetidin. The pharmaceutical mechanism of WNG proved that it could inhibit the secretion of pepsin. The acute and chronic poisoning test was negative both in vitro and in vivo. WNG were nearly no any side effects in this study. Therefore it is a new type of herbs in treatment of chronic superficial gastritis and is different from H2-receptor inhibitor.

Adult↗
PubMed1987

Transcortical sensory aphasia in China.

Three cases of transcortical sensory aphasia in Chinese speakers were associated with left parieto-temporal junction strokes. The possibility that this relatively rare aphasia syndrome is more common in the Chinese is raised and a theoretical explanation based on differences in Oriental written language is presented.

Aphasia↗
PubMedDate not supplied

Estimating odds ratios adjusting for misclassification in Alzheimer's disease risk factor assessment.

Epidemiological studies of Alzheimer's disease and dementia are often two-phase studies including a screening phase and a clinical assessment phase. It is common to interview a relative of the subject at each of these phases to obtain information about the subject's exposure to risk factors. This can result in a misclassification error when assessing risk factors, as the two responses of the relative often differ. This is especially a problem for risk factors involving life-style and family history which cannot be confirmed using the subject's medical records. A naive analysis using data from each phase separately would give two different estimates of the odds ratio; both estimates could be biased. In this paper, we extend the estimation methods adjusting for misclassification developed by Liu and Liang to data collected through two-phase sampling. We first use a latent class analysis and the EM algorithm to estimate the misclassification parameters. We then derive the maximum pseudo-likelihood estimators, conditional on the misclassification parameters, to estimate the odds ratios accounting for the complex sampling study design. We propose to use the jack-knife estimator for estimation of the variances. We apply the above method to data collected in the Indianapolis-Ibadan Dementia Study to estimate the odds ratio for smoking adjusting for misclassification error.

Black or African American↗