PubMed Health⌕ Search

Biomedical subjects

W M Cai

Publications and source records attributed to W M Cai.

At least 37 records · Page 2Linked to original sources
PubMed1998

[Identification of gravity-related esterases (grEST1 and grEST2) in carrot callus cells].

A horizontal clinostat which mimics the microgravity in space was used to study its effects on carrot cells. After using boric acid buffer (pH 8.8) as extraction medium, PAGE pattern of esterase isozymes of carrot callus cells displayed 8 bands of which the activities of only 2 were affected by microgravity. They were named grEST1 and grEST2, where grEST stands for gravity-related esterase. The rates of increase in activity of them in carrot cells when cultured on a rotating horizontal clinostat were lower than that cultured in normal gravitational environments, and the difference increased with the culture time. The activities of grEST1 and grEST2 in carrot callus cells subjected to horizontal rotation were found to return to their original levels after being placed under normal gravity (1 x g) for 7 days. We suggest that the effect of simulated microgravity conditions on grEST1 and grEST2 activities in carrot callus cells is through affecting their synthesis. In addition, the activities of grEST1 and grEST2 were not inhibited by eserine, acetylcholine iodide, diisopropyl fluorophosphate and p-chloromercuribenzoate, which indicates that they are acetylesterases.

Acetylcholine↗
PubMed1997

Dextromethorphan metabolic phenotyping in a Chinese population.

AIM: To establish a phenotyping of dextromethorphan (DM) oxidation polymorphism in a native Chinese population. METHODS: The urine concentrations of DM and its metabolite dextrophan (DX) were assayed by HPLC and metabolic ratios (MR) were calculated in 120 unrelated native Chinese subjects after ingestion of DM 20 mg. RESULTS: The incidence of poor metabolizers was 0.8% (one in 120 subjects). There were distinct dimodal distributions which divided extensive metabolizers into 43 intermediate metabolizers and 76 very extensive metabolizers. The 0-8 h urinary recoveries of DM and DX were 0.4% +/- s 0.5% and 26% +/- s 13%, respectively. There was no difference in 0-8 h urinary recoveries between male and female subjects. CONCLUSION: DM metabolic phenotyping provides a new information for debrisoquine 4-hydroxylation (CYP2D6) polymorphism in native Chinese.

Adolescent↗
PubMed1997

Displacement of statoliths in Chara rhizoids during horizontal rotation on clinostats.

The basipetal movement of statoliths in Chara rhizoids, similar to that during parabolic flights of TEXUS rockets occurs also during rotation on clinostats. Within 15 min on fast-rotating clinostat, the distance between the center of the statolith complex and the cell vertex increases for 60% of that in positively gravitropic downward growing rhizoids. Cytochalasin D experiments confirm that the movement of statoliths is actin-dependent and the actin filaments exert basipetal forces on statoliths in gravity field. The clinostat and/or cytochalasin experiments confirm the suggestion that on earth the position of statoliths depends on the balance of the gravitational force and the counteracting force mediated by actin filaments. The statolith center keeps a stable position during about 30 min on a fast-rotating clinostat, i.e. it is then in a new dynamically stable state. This new state is achieved 15 min after the basipetal acting filament-mediated force has been disturbed by clinostatting. Further experiments on the fast-rotating clinostat show that this new position brings about a reorganization of actin filaments which makes the process of acropetal transport of statoliths possible. The amplitude of particle oscillatory movement decreases as the rotational speed of the clinostat increases. This explains the differences of the results obtained from the experiments on fast-rotating and slow-rotating clinostats. It should be kept in mind that rhizoids are unicellular. The fast-rotating clinostat is suitable for simulation of conditions without gravity when a rhizoid is on the axis of rotation. The interaction of statoliths and actin filaments at zero gravity can be studied by means of such a clinostat.

Actin Cytoskeleton↗
PubMed1997

[Distinguishing CYP2D6 homozygous and heterozygous extensive metabolizers by dextromethorphan phenotyping].

A more sensitive procedure was developed to phenotype cytochrome P450 2D6 metabolism by a less toxic probe drug--dextromethorphan. The sensitivity of the determination of dextromethorphan in urine samples was up to 1 ng.ml-1. This method was employed to phenotype three groups of subjects. The results showed that there was a difference between extensive metabolizers which were genotyped as homozygotes and heterozygotes. Although the difference was not as big as the difference with poor metabolizers which were genotyped as homozygous mutants. It suggests that "gene copy" is a true factor in the expression of CYP2D6 genes.

Chromatography, High Pressure Liquid↗
PubMed1997

High performance liquid chromatographic determination of dextromethorphan and its metabolite in human urine.

A reverse-phase high-performance liquid chromatographic method was established for the determination of dextromethorphan (DM) and its metabolite dextrophan (DX) in human urine. The sample was purified by an acid-base extraction followed by HPLC analysis on a phenyl column. The eluate was monitored by fluorescence at 280 nm (excitation) and 310 nm (emission). The limit of detection of DM was 0.023 mg.L-1. The within-day and between-day RSD% of DM and DX were all lower than 5%. The average recovery was 104.78%.

Chromatography, High Pressure Liquid↗
PubMed1996

[Analysis of population pharmacokinetics with NONMEM in clinical patients treated with amikacin by intravenous infusion].

Clinical data (n = 275) collected from 52 patients with respiratory tract infection receiving amikacin (AMK) by intravenous infusion were analysed with NONMEM, a computer program designed for estimating population pharmacokinetic parameters. Concentrations of AMK in serum were determined by fluorescence polarization immunoassay (FPIA). A two compartment open model was used for analysing AMK population pharmacokinetics. The influence of body weight (BW), creatinine clearance (CC), administration history (HIS) and state of pathology (chronic obstructional pulmonary disease, COPD) on pharmacokinetics was investigated. The pharmacokinetic parameters of AMK were shown to be influenced by creatinine clearance (CC) and COPD.

Adult↗
PubMed1994

A simplified high-performance liquid chromatographic method for direct determination of warfarin enantiomers and their protein binding in stroke patients.

A simplified method for direct determination of warfarin enantiomers by high-pressure liquid chromatography with fluorescence detection has been developed. This method involves solid phase extraction of warfarin in plasma, precolumn derivatization to form diastereoisomeric esters, and post-column reaction to discriminate each enantiomer separately. Ultrafiltration was employed in the separation of unbound warfarin enantiomers. Twelve plasma samples from six stroke patients taking warfarin regularly were analyzed. The average concentration of total warfarin was 0.47 +/- 0.17 mg/L for the S-isomer and 0.69 +/- 0.18 mg/L for the R-isomer. The average protein binding was 99.67 +/- 0.33% for S-warfarin and 99.44 +/- 0.33% for R-warfarin. This methodology provides a quick and reliable technique for determining enantiomeric protein binding of warfarin in clinical settings.

Aged↗
PubMed1993

Free phenytoin monitoring in serum and saliva of epileptic patients in China.

Twenty-three serum samples and 13 saliva samples from 14 Chinese epileptic patients treated with phenytoin (DPH) were obtained to study the correlations between total, free serum, and saliva DPH concentrations. The binding of DPH to serum protein was assessed by equilibrium dialysis, and total and free DPH concentrations were analyzed with a domestic fluorescence polarization immunoassay reagent by the TDx system. A strong correlation existed between the total and free concentrations (r = 0.90, n = 20, p < 0.001). The mean value for the DPH free fraction was 11.13 +/- 3.65%. The mean value for the saliva fraction was 9.40 +/- 2.60%. This is the first attempt to monitor free DPH concentrations in serum in Chinese patients.

Administration, Oral↗
PubMed1993

Influence of serum separator tubes on total and free phenytoin concentrations and dosages.

The influence of serum separator tubes (SSTs) on total and free phenytoin concentrations and phenytoin dosages was evaluated in patients treated with phenytoin. Thirty blood samples were obtained from 18 patients. Equal volumes of blood were placed into SSTs and plain tubes. Samples were centrifuged, and serum analyzed for total and free phenytoin by fluorescence polarization immunoassay (FPIA) at 2, 24, and 48 h. Total phenytoin concentrations collected in SSTs were significantly lower than those collected in plain tubes at 2 (12.3 vs 12.8 mg/L, p < 0.01), 24 (11.4 vs 12.9 mg/L, p < 0.01), and 48 h (10.9 vs 12.9 mg/L, p < 0.01). These differences resulted in significantly higher calculated maximum rates of metabolism (Vmax) and daily phenytoin dosages (R0) for SSTs at 24 (Vmax: 10.4 vs 10.1 mg/kg/day; R0: 8.2 vs 8.0 mg/kg/day, p < 0.01) and 48 h (Vmax: 10.8 vs 10.3 mg/kg/day; R0: 8.5 vs 8.1 mg/kg/day, p < 0.01). Free phenytoin concentrations from SSTs were significantly lower at 48 h (1.56 vs 1.61 mg/L, p < 0.05). However, there were no significant differences in calculated dosages. Observed statistical differences in total phenytoin concentrations can be clinically important for making dosage adjustments, especially in patients undergoing nonlinear elimination. Thus, SSTs should not be used to collect blood for total serum phenytoin determination.

Adult↗
PubMed1993

Preliminary experience in HDR brachytherapy for 72 nasopharyngeal carcinoma patients.

From April 1989 to July 1991, 72 patients with residual or recurrent nasopharyngeal carcinoma (NPC) were treated by MSH Ir-192 brachytherapy or combined external radiation therapy. All were proven histologically. 39 patients with residual disease and 6 with recurrent lesion at the primary site were identified after one or more courses of radical external radiation. Eleven patients had received brachytherapy for boost therapy after one or more courses of external radiation. Sixteen were treated with a planned protocol of external irradiation combined with intracavitary brachytherapy. The overall local control rate was 93.3%; the local control rate for residual and recurrent disease was 100% and 50%, respectively. Soft palate perforation was observed in 3 patients. Brachytherapy is believed to be a useful treatment for residual or recurrent NPC following radical external radiation.

Adolescent↗
PubMed1992

Studies on ultrasonographic diagnosis of schistosomiasis japonica in China--a review of selected Chinese studies.

Diagnostic ultrasound has been used in China since the early 1960's in the investigation of Schistosoma japonicum infection. This paper presents an overview of selected papers from the Chinese literature on the use of ultrasound in studies of schistosomiasis japonica, and briefly reports the results of studies not yet published elsewhere. The method is compared with other diagnostic procedures, and the benefits and limitations of using ultrasound are discussed.

Adult↗
PubMed1992

[The activity of tumor necrosis factor in schistosomiasis japonica].

The activity of tumor necrosis factor (TNF) in both the culture supernatant of peripheral blood mononuclear cells (PBMC) and the serum was examined in 20 patients of advanced schistosomiasis at 8th week after pyquiton treatment, and 6 rabbits infected with S. japonicum cercariae at 8th and 16th weeks post-infection and using L929 cell cytotoxic assay. The results showed that the capacity of PBMC to produce TNF in response to LPS from patients with late schistosomiasis was significantly lower than that from normal subjects (P less than 0.01), whereas the activity of TNF in serum was significantly elevated (P less than 0.01). The capacity of PBMC to produce TNF and the TNF activity in serum of infected rabbits showed sharp rise at 8th week post-infection (P less than 0.01), and remained high at 16th week, then returned to normal level 8 weeks after treatment. The persistent rise of TNF in the circulation indicate that TNF might take part in the formation of hepatic fibrosis.

Adult↗
PubMed1991

A Bayesian graphic method for predicting individual phenytoin dosage schedule.

A simple and practical graphic method based on Bayesian feedback theory for predicting individual phenytoin dosage was evaluated. Compared with the mathematical calculation, the graphic method only needs one pair of steady-state phenytoin concentration-dose data to predict individual phenytoin dosage. The observed drug levels were compared with predicted ones in 12 epileptic out-patients with a correlation coefficient of 0.94. The mean error between the observed and predicted phenytoin levels was 0.62 mg.L-1. The mean kinetic parameters Vm and Km obtained from the graph were 7.01 +/- SD 0.88 mg.kg-1.d-1 and 4.93 +/- 0.91 mg.L-1, respectively.

Adolescent↗
PubMed1990

Photodynamic therapy in the treatment of malignant tumours: an analysis of 540 cases.

Malignant tumours (540 cases), including tumours of the lung, oesophagus, cardia, stomach, rectum, bladder, other urinary genital organs, face and mouth, eyes, ear, nose and throat (ENT), head and neck, breast and skin, were treated using photodynamic therapy (PDT) between 1982 and 1985 in Beijing. All of the cases were identified pathologically and the patients received haematoporphyrin derivative (HPD) (5 mg kg-1) intravenously 48-72 h prior to PDT. An argon-pumped dye laser emitting at 630 nm was used for the treatment. The results were as follows: complete response (CR) was obtained in 227 cases (42.1%), partial response (PR) was obtained in 114 cases (21.1%), mild response (MR) was obtained in 120 cases (22.2%) and 79 cases (14.6%) showed no response (NR). The effectiveness of PDT in the different organs was compared. HPD fluorescence was examined in 409 cases of malignant tumours: 344 lesions (84.1%) revealed red fluorescence (positive reaction), 32 gave an equivocal response and 33 gave a negative reaction. Positive fluorescence was seen in all types of malignant tumour in our study. Indications and limitations of PDT for the different organs are discussed and compared.

Argon↗
PubMed1990

[Result and indication of photodynamic therapy in the treatment of malignant tumors--analysis of 165 patients].

Evaluation of the effect of photodynamic therapy (PDT) on cancers is presented. Indication of PDT in the treatment of 165 cancer patients, including 68 superficial, 33 head and neck, 57 bladder and 7 other cancers treated from Sept. 1981 through 1985 is reported. The overall effective rate was 83.6%. The immediate response rates were as follows: complete response 58.2%, marked response 13.3%, mild response 12.1% and no response 16.4%. The longest cancer-free survival was over six years. Based on this material the indications of PDT on cancer are suggested as: 1. superficial and early cancers; 2. orifice obstruction in the alimentary or respiratory tract; 3. local residual or recurrent cancer after surgery or radiotherapy; 4. bladder cancer. The disadvantages of PDT are discussed.

Carcinoma, Squamous Cell↗
PubMed1990

[Use of fluorescence polarization immunoassay and microbiological assay in the study of gentamicin pharmacokinetics in man and a comparison of the results].

Ninety serum samples of gentamicin were determined by fluorescence polarization immunoassay (FPIA) and microbiological assay (MA) and the results were compared. Liner regression analysis showed that the two methods were highly correlated with a correlation coefficient of 0.98. The mean concentration of gentamicin as determined by MA method was significantly higher than that by FPIA method. Serum concentration-time data derived from 5 patients were fitted to a one-compartment model. No significant differences in the pharmacokinetic parameters and estimated dosages were observed. The FPIA method was shown to be as correct and reliable as the MA method in estimating gentamicin pharmacokinetic parameters.

Abdomen↗
PubMed1989

Chinese herb "destagnation" series I: Combination of radiation with destagnation in the treatment of nasopharyngeal carcinoma (NPC): a prospective randomized trial on 188 cases.

The results of a prospective randomized trial on 188 patients with NPC is reported to evaluate the validity of Chinese herbal medicine-Destagnation combined with radiotherapy. Ninety patients were allotted to the Destagnation group (radiation plus Destagnation) and 98, to the control group (radiation only). The 5-year success rate (number surviving minus number recurred but salvaged by re-treatment) of the Destagnation group is 53% (48/90) in comparison to 37% (36/98) of the control group (p less than 0.05). Minor complications of Destagnation included occasional anorexia and frequency of bowel movement. The reduced rate of local recurrence at the primary site in the Destagnation group (14%-13/90) as compared to that of the control group (29%-28/98) (p less than 0.05) suggests that Destagnation may be a radiosensitizer. The similar metastatic rates in both groups; 21% (19/90) in the Destagnation group and 21% (21/98) in the control group may refute the belief that Destagnation enhances hematogenous spread.

Adult↗