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Biomedical subjects

C T Hung

Publications and source records attributed to C T Hung.

At least 73 records · Page 4Linked to original sources
PubMed1989

Physiological pharmacokinetic model of adriamycin delivered via magnetic albumin microspheres in the rat.

The influence of magnetic albumin microspheres on the disposition of adriamycin was evaluated. Adriamycin concentrations were monitored in multiple rat tissues for 48 hr after its intra-arterial administration (2 mg/kg) as a solution and associated with magnetic albumin microspheres. The magnetic dosage form was targeted to a predefined tail segment with a magnetic field strength of 8000 G applied for 30 min after dosing. A physiological pharmacokinetic model was used to describe the disposition of adriamycin following its administration from either dosage form. The model developed for the data resulting from administration of adriamycin as a solution served as a foundation for the model developed for adriamycin resulting from the administration of adriamycin associated with the magnetic dosage form. The model for adriamycin following administration of the magnetic microspheres required additional relationships to describe the transport of adriamycin associated with the microspheres. For both models, the predicted adriamycin concentrations were in adequate agreement with the observed values. The present investigation demonstrates the use of a physiological pharmacokinetic modeling method to represent drug kinetics following its administration via a targeted drug delivery system.

Albumins↗
PubMed1989

Magnetically controlled targeted micro-carrier systems.

Magnetically controlled targeted drug delivery systems are aimed at concentrating drugs at a defined target site, with the aid of a magnetic field. This technique has been developed specifically for directing drugs away from the reticuloendothelial system (RES). Literature on this topic suggests that these delivery systems are capable of altering the distribution of chemotherapeutic agents in the body. Hence these delivery devices offer the possibility of improving the therapeutic efficacy of the associated drugs. This paper reviews the work done to date towards the development and evaluation of biodegradable and non-biodegradable magnetic targeted drug delivery systems and outlines their future prospects and limitations in cancer chemotherapy.

Albumins↗
PubMed1989

Design of a new hydrocolloid dressing.

Hydrocolloid dressings composed of dextran, phospholipid, glycerol and sodium lauryl sulphate have been formulated. A ventilated hygrometer system has been used to study the evaporative water loss (EWL) from the excised wound of rats with and without these dressings. A statistical experimental design has been used to locate a formulation which is flexible and semiocclusive in nature. The phospholipid component of the dressing has a significant role in controlling water vapour permeability of the dressing. The EWL from the excised wound covered with the optimized dressing has been compared with that for two commercial products.

Animals↗
PubMed1989

Interaction of L-ascorbic acid on the disposition of lead in rats.

L-Ascorbic acid (As-Ac) has been investigated for its potential in the prophylaxis of lead poisoning. Using rats as the animal model, the pharmacokinetics of As-Ac was determined following a single intravenous dose (100 mg/kg) administered through a jugular vein. Plasma As-Ac levels were monitored using an enzyme assisted UV spectrophotometric method. The pharmacokinetic parameters of As-Ac obtained were used to establish a dosage regimen which could maintain its average plasma concentration of about 11 micrograms/ml at steady state in rats. The disposition of lead acetate (1 mg/kg) in rats was studied in the absence and presence of As-Ac at steady state. Lead concentrations were monitored in femur, kidney, liver and plasma over a 120 hr period using flameless atomic absorption spectrophotometry. In presence of As-Ac, femur, kidney and liver demonstrated 56, 22 and 41% respective reductions in their exposure towards lead. In addition, the half-life of lead in femur and plasma was found to be reduced by 27 and 51% respectively.

Animals↗
PubMed1989

Effects of high-fructose (90%) corn syrup on plasma glucose, insulin, and C-peptide in non-insulin-dependent diabetes mellitus and normal subjects.

Interest in sweetening agents is encouraging manufacturers and researchers to find a safe substance to maintain the life quality of diabetics. The popularity of sweetened food items has increased recently in Taiwan. The glycemic index of fructose has been reported to be 20%, much lower than most carbohydrate foods. A high-fructose corn syrup (HFCS) has come onto the market of sweetening agents and has been proposed as a low-cost substitute for fructose in dietetic management of diabetes. The aim of this study was to compare the glycemic effects of HFCS and glucose to see if there is a place for high-fructose corn syrup in diabetic management. In 8 normal and 21 non-insulin dependent diabetes mellitus (NIDDM) subjects, we performed oral tolerance tests. After an overnight fast, the subjects were given either 75g of glucose or an equivalent amount of HFCS containing 75g of carbohydrate. Blood was sampled before and at 30, 60, 90, 120 and 180 minutes after the glucose load. Blood glucose was analyzed by the glucose oxidase method using YSI 23 A (Yellow-Springs Intrument). The insulin and C-peptide were measured by RIA kits from Daiichi. The area under the curves (AUC) was calculated for plasma glucose, immunoreactive insulin (IRI) and immunoreactive C-peptide (IRCP). The results showed that the glycemic effect of HFCS was 73% of glucose. The AUC of IRI after HFCS was 56% of that of glucose. The AUC of IRCP after HFCS was 57% of that of glucose. The high glycemic index of HFCS in our study does not support the use of HFCS as a substitute for fructose.

Adult↗
PubMed1989

Food exchange list based on 80-kilocalorie rice unit.

The conventional food exchange list which has been used in most hospitals and nutrition related institutes in Taiwan is derived from that published by a Joint Committee of the American Diabetes Association, American Dietetic Association, and the Diabetes Section, U.S. Public Health Services in 1950. There are several disadvantages of using this conventional table as an educational tool for Chinese patients in Taiwan. Those disadvantages include ignorance of macronutrients, nonnutritional classification of food and variance in calories between food categories. Our food exchange list aimed to classify food items into carbohydrate, protein and fat-rich food groups isocalorically. First of all, a "rice-unit" is defined as a 1/4 bowl of cooked rice, which contains approximately 80 kcal. Second, 80 kcal derived from the "rice unit" was used as a basic calorie unit in this study for definition of carbohydrate-rich, protein-rich, and fat-rich food items. All of the following items contain approximately 80 kcal: 1/2 bowl of gruel, a small banana, two medium sized oranges, a slice of bread (carbohydrate-rich items), an egg, 38g of pork (protein-rich items) and two teaspoons of soybean oil (a fat-rich item). There are several benefits of using this recommended food exchange list: (1) Rice is the most important staple in the Chinese family. The recommended food exchange list is derived from rice to enhance practicality and compliance of the Chinese people in Taiwan. Moreover, the theory of a high carbohydrate, high-fiber diet recommended by the ADA in 1987 has been stressed in this study.(ABSTRACT TRUNCATED AT 250 WORDS)

Diabetes Mellitus↗
PubMed1988

Optimization of high-performance liquid chromatographic analysis for isoxazolyl penicillins using factorial design.

A 3 X 3 factorial design has been used to study the effects of pH and acetonitrile concentration of the eluents on the retention and resolution of cloxacillin, flucloxacillin and dicloxacillin on a C18 column. The logarithm of the capacity factors of these solutes have been found to vary linearly with the pH and quadratically with the acetonitrile content. The equations generated have been employed to predict experimental conditions necessary for an optimum separation. The chromatographic condition selected has been applied to the quantitation of flucloxacillin in human plasma using dicloxacillin as the interval standard. Sample preparation consists of protein precipitation and solid-phase extraction. The detection limit of the assay at 220 nm for flucloxacillin is in the region of 0.1 microgram/ml. This assay has been employed in a study of the relative bioavailability of two commercial flucloxacillin sodium capsules in ten healthy volunteers.

Adult↗
PubMed1988

Optimized synthesis of polyglutaraldehyde nanoparticles using central composite design.

A central composite design was applied to the optimization of the synthesis of polyglutaraldehyde nanoparticles (PGNP). The effects of monomer concentration, surfactant concentration, pH, oxygen level, and stirring rate on the particle size, polydispersity, surface carboxyl group concentration, and yield of PGNP were investigated. The optimal conditions for the synthesis of PGNP were found to be: 7% (w/v) glutaraldehyde, 2.5% (w/v) dextran, pH 12, 70% (v/v) oxygen, and a stirring rate of 1080 rpm. Under these conditions, the values of the dependent variables adequately resembled those predicted by the model. The usefulness of these particles in the targeted delivery of cytotoxic drugs is discussed.

Aldehydes↗
PubMed1988

Stability of morphine solutions in plastic syringes determined by reversed-phase ion-pair liquid chromatography.

A reversed-phase ion-pair HPLC assay has been developed for quantitating morphine, codeine, apomorphine, and pseudomorphine in aqueous solutions. Using two types of plastic syringes, the effect of light (25 W) and temperature (22 and 3 degrees C) on the stability of morphine, over a 12-week period, has been investigated in the presence and absence of preservative and antioxidant. The leaching of contaminants from the plastic syringes to water stored in them, for a period of up to 12 weeks, has also been investigated. The results indicate that less than 3% of the morphine is degraded in both types of plastic syringes, stored in light at 22 +/- 2 degrees C. The degradation is even less prominent in the dark or at 3 degrees C. Pseudomorphine has been identified as the major degradation product. Using 5% degradation of drug as the criterion for the determination of the shelf-life of morphine, it was found that in one brand of plastic syringes, morphine has a shelf-life of the order of 20 and 33 weeks, in the absence and presence of preservative and antioxidant, respectively. In the other brand of plastic syringe, the drug has a shelf-life of greater than 1 year. Some unidentified leached contaminants have been detected in water stored in both brands of syringes.

Apomorphine↗
PubMed1987

Chromatography of progesterone and its major metabolites in rat plasma using microbore high-performance liquid chromatography columns with conventional injection and detection systems.

A separation of progesterone and its metabolites 17 alpha-hydroxyprogesterone, 20 alpha-hydroxy-4-pregnen-3-one, androstenedione and testosterone by high-performance liquid chromatography with a ternary solvent system is demonstrated. It is found that using a 100 X 1 mm microbore column, higher sensitivity is obtained in the ultraviolet detection of these compounds by using conventionally sized flow cells despite the higher efficiency resulting from the use of a micro-flow cell. It is also shown that, when a non-eluting solvent is used for injection, large injection volumes do not reduce column efficiency, and a 14-fold increase in sensitivity is obtained with a 1-mm column in place of one 4.6 mm in diameter. Using solid-phase extraction and concentration of the sample as pretreatment, progesterone and its hydroxylated metabolites are determined in 0.5-ml samples of rat plasma. The progesterone levels are compared with those obtained by radioimmunoassay.

17-alpha-Hydroxyprogesterone↗
PubMed1987

Analysis of p-aminobenzoic acid and its metabolites in urine and plasma by ion pair HPLC in the NBT-PABA pancreatic function test.

An ion pair HPLC method which can simultaneously detect the major metabolites of an exocrine pancreatic function testing agent (NBT-PABA) in plasma and urine has been developed. This assay has been applied to a pharmacokinetic study of PABA and its metabolites in 3 healthy adult volunteers following the oral administration of 1 g NBT-PABA. The 6 h testing period currently used to collect urine following the NBT-PABA ingestion is adequate for the recovery of PABA and its metabolites. Plasma determination of these compounds may provide an improved evaluation of the pancreatic performance in patients with abnormal liver or kidney function.

4-Aminobenzoic Acid↗
PubMed1987

Determination of pharmacokinetics of cocaine in sheep by liquid chromatography.

Cocaine was administered as 1-, 2-, and 4-mg/kg intravenous bolus doses to each of six sheep. Plasma samples were collected as a function of time and assayed for cocaine using reversed-phase ion-pair HPLC. The assay involved double extraction with ether and UV detection at 229 nm. Using 2 mL of plasma, levels of 1 ng/mL of cocaine can be measured. The concentration versus time data obtained for the plasma samples were analyzed by a "noncompartmental" method. The pharmacokinetic parameters of cocaine in sheep had mean values of 4.0 L/kg, 3.5 L/kg, and 0.29 L X min-1 X kg-1 for Vd, Vdss, and CL respectively. The clearance of cocaine in sheep was much higher than cardiac output. Pulmonary first-pass effect has been suggested as the possible explanation for the large clearance of cocaine in sheep.

Animals↗
PubMed1987

Quantitation of the release of doxorubicin from colloidal dosage forms using dynamic dialysis.

The release of doxorubicin from submicrometer bovine serum albumin (BSA) microspheres has been quantitated using dynamic dialysis. Mathematical models have been proposed based on zero- or first-order release of drug from solid colloidal matrices. The models also account for the permeability constant of the dialysis membrane. Results obtained by the dynamic dialysis technique resemble those obtained using a conventional dissolution method. The release of doxorubicin from the microspheres can be adequately described by a biphasic zero-order model.

Colloids↗
PubMed1986

Reversed-phase ion-pair high-performance liquid chromatography of adriamycin and adriamycinol in rat serum and tissues.

An ion-pair reversed-phase high-performance liquid chromatographic method is presented for the determination of adriamycin and adriamycinol concentrations in rat serum and tissues. The scheme for developing the chromatographic conditions is discussed. A good separation of adriamycinol and adriamycin was obtained by using a high sodium lauryl sulphate concentration in the mobile phase. The retention times of adriamycinol, adriamycin and daunomycin (internal standard) were less than 3 min with no interfering peaks from endogenous constituents. A protein precipitation method was used to prepare the serum and tissue samples for injection.

Journal Article↗
PubMed1986

Fasting and feeding variations of insulin requirements and insulin binding to erythrocytes at different times of the day in insulin dependent diabetics--assessed under the condition of glucose-controlled insulin infusion.

Nine insulin-dependent diabetic patients were examined for insulin requirement, counterregulatory hormones, and receptor binding during their connection to glucose-controlled insulin infusion system. They were of 103% ideal body weight. A diet of 45% carbohydrate, 20% protein and 35% fat was divided into three meals and three snacks averaging the daily calorie intake of 1859 kcal. Following an equilibrating phase of 14 hours after the connection to the glucose-controlled insulin infusion system the blood samples were taken at 0800, 1200 and 1800. The insulin infusion rate increased at 0300 in the early morning from 0.128 mU/kg/min to 0.221 mU/kg/min (P less than 0.02). The postprandial insulin infusion rate jumped from 0.7 U/h (0700-0800) to 7.5 U/h (0800-0900). The calorie related and carbohydrate related insulin demands after breakfast were also highest and declined after lunch respectively (1.16 uU/kg/min kj vs. 0.61 uU/kg/min kj, P less than 0.05 and 236 mU/g CHO vs. 129 mU/g CHO and 143 mU/g CHO). Of the counterregulatory hormones the cortisol showed a significant diurnal rhythm to insulin demands. The insulin tracer binding was higher at 0800 before breakfast than that at 1200 before lunch (P less than 0.05). The increased binding could be better attributed to receptor concentration change than to affinity change. The cause of insulin relative insensitivity in the morning could be due to altered liver response to the cortisol peak in type 1 diabetics. The preserved variation of insulin binding in our patients might be referred to feeding.

Circadian Rhythm↗
PubMed1985

Analysis of 5'-deoxy-5-fluorouridine and 5-fluorouracil in human plasma and urine by high-performance liquid chromatography.

A relatively simple and sensitive high-performance liquid chromatographic (HPLC) method is described for measuring the two anticancer drugs 5'-deoxy-5-fluorouridine (5'dFUR) and 5-fluorouracil (5-FU) in human plasma and urine. The procedure for plasma includes solvent extraction using ethyl acetate-isopropyl alcohol (85:15) followed by silica gel column chromatography to separate these compounds from constituents normally occurring in plasma. The analysis by reversed-phase HPLC is performed on a phenyl column using an aqueous mobile phase with ultraviolet detection (280 nm). The overall recovery from plasma was 61% and 65% for 5'dFUR and 5-FU, respectively. The sensitivity limit of the assay for both compounds was 50 ng/ml of plasma. Analysis of these compounds in urine did not require the silica column chromatography isolation step.

Chromatography, High Pressure Liquid↗