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Biomedical subjects

G B Park

Publications and source records attributed to G B Park.

At least 19 recordsLinked to original sources
PubMed2002

Effects of dietary conjugated linoleic acid on fatty acid composition, lipid oxidation, color, and water-holding capacity of pork loin.

The effects of dietary conjugated linoleic acid (CLA) on fatty acid composition, lipid oxidation, and pork quality were investigated. Pigs (n = 20) were fed a diet containing 0, 1, 2.5, or 5% CLA for 4 wk and slaughtered at 105 kg. The longissimus thoracis et lumborum muscle was collected at 24 h postmortem. Pork loin chops (3 cm thick) were packaged aerobically and stored at 4 degrees C for 7 d. Samples were analyzed for ultimate pH, intramuscular fat content, fatty acid composition, thiobarbituric acid-reactive substances, color (L*, a*, b*), and water-holding capacity. Dietary CLA reduced the concentration of linoleic acid and increased CLA concentration in intramuscular fat of pork loin (P < 0.05). The concentration of CLA in muscle was increased with dietary CLA level and did not change during storage. Thiobarbituric acid-reactive substance value of control was higher than that of the CLA-fed groups (P < 0.05). Intramuscular fat content was increased by dietary CLA, and less purge loss was observed with samples from CLA-fed pigs (P < 0.05). Dietary CLA improved the color stability of pork loin during cold storage. After 7 d, lightness (L*) and yellowness (b*) of the 5% CLA-fed group were significantly lower than those of control (P < 0.05). The results indicated that the water-holding capacity of pork loin was increased with increased intramuscular fat content apparently caused by dietary CLA. Also, the data indicated that color stability of pork was improved with inhibition of lipid oxidation and changing of fatty acid composition by dietary CLA.

Animals↗
PubMed2002

Influence of slaughter weight and sex on yield and quality grades of Hanwoo (Korean native cattle) carcasses.

To assess the effects of slaughter weight and sex on APGS (Animal Products Grading Service) quality and APGS yield grade of Korean Hanwoo (n = 20,881) cattle, data were collected from cow, bull, and steer carcasses during a 1-yr period. Factors used to determine quality grade (marbling, meat color, fat color, texture, and overall maturity score) and yield grade (cold carcass weight, adjusted fat thickness, and longissimus muscle area) by the Korean grading system were recorded. Both yield and quality grades were improved (P < 0.01) with heavier slaughter weight, but there was no difference in yield grade for Hanwoo cattle classes heavier than 551 kg (P > 0.01). Longissimus muscle area, adjusted fat thickness, and marbling score increased (P < 0.01) with carcass weight. Bull carcasses showed higher yield but lower quality than those of cows or steers (P < 0.01). The quality grade of steer carcasses was higher (P < 0.01) than that of cow carcasses due to higher marbling scores, lower maturity scores, and heavier carcass weights. Hanwoo carcasses with larger longissimus muscle areas in relation to their carcass weight had lower APGS quality grades. The APGS quality grades were different between yield grade A and B carcasses (P < 0.01), but quality grade was not improved by increased fat thickness beyond the point of yield grade B. Adjusted fat thickness and marbling score showed significant (P < 0.01) differences among all yield grade classes, and this resulted in increased quality grade as yield grade decreased. Adjusted fat thickness showed the strongest correlation (r = -0.63) with yield grade, whereas marbling score had the strongest correlation (r = 0.81) with quality grade. Results showed a negative effect of castration on yield but a positive effect on quality. Also, data showed that Hanwoo carcasses with heavier weights had higher quality grades than those of lighter weight.

Animals↗
PubMed2000

Improvement of oxidative stability of conjugated linoleic acid (CLA) by microencapsulation in cyclodextrins.

Oxidative stability of conjugated linoleic acid (CLA) encapsulated in alpha-, beta-, and gamma-cyclodextrins (designated CLA/CDs microencapsules) was studied by measuring the headspace-oxygen depletion in airtight serum bottles and by measuring the peroxide values (POV). The rate of oxygen depletion was reduced from 41.0 (control) to 21.5, 2.1, 1.2, and 1.1 micromol/L.h(-)(1) by CLA/alpha-CD microencapsules at 1:1, 1:2, 1:4, and 1:6 mole ratios, respectively, indicating that CLA oxidation was completely protected by a 1:4 mole ratio of CLA/alpha-CD. Such a protective effect by CLA/beta-CD or CLA/gamma-CD microencapsules was achieved at a 1:6 mole ratio, but the effect by CLA/beta-CD was slightly greater than that by CLA/gamma-CD. The protective effect of alpha-, beta-, and gamma-CDs for CLA oxidation was confirmed by their POV-reducing abilities in CLA/CDs. These results suggest that alpha-CD was the most effective for the protection of CLA oxidation by microencapsulation, followed by beta-CD and gamma-CD.

Cyclodextrins↗
PubMed1994

The physicochemical properties, plasma enzymatic hydrolysis, and nasal absorption of acyclovir and its 2'-ester prodrugs.

A series of 2'-(O-acyl) derivatives of 9-(2-hydroxyethoxymethyl)guanine (acyclovir) was synthesized by acid anhydride esterification. Aqueous solubilities in isotonic phosphate buffer (pH 7.4), partition coefficients in 1-octanol/phosphate buffer, and hydrolysis kinetics in rat plasma were determined. The ester prodrugs showed consistent increases in lipophilicity with corresponding decreases in aqueous solubility as a function of side-chain length. The bioconversion kinetics of the prodrugs appear to depend on both the apolar and the steric nature of the acyl substituents. When perfused through the rat nasal cavity using the in situ perfusion technique, acyclovir showed no measurable loss from the perfusate. Nasal uptake of acyclovir prodrugs, on the other hand, were moderately improved. Furthermore, the extent of nasal absorption appears to depend on the lipophilicity of the prodrugs in the descending order hexanoate > valerate > pivalate > butyrate. Simultaneous prodrug cleavage by nasal carboxylesterase was also noted in the case of hexanoate.

Absorption↗
PubMed1992

Acyclovir permeation enhancement across intestinal and nasal mucosae by bile salt-acylcarnitine mixed micelles.

The purpose of this study was to investigate the absorption enhancement of acyclovir, an antiviral agent, by means of bile salt-acylcarnitine mixed micelles. The specificity, site dependence, palmitoyl-DL-carnitine chloride (PCC) concentration dependence, and effects of absorption promoters on acyclovir absorption via the nasal cavity (N) and four different intestinal segments of the rat, i.e., duodenum (D), upper jejunum (UJ), combined lower jejunum and ileum (LJ), and colon (C) were evaluated. The present study employed the rat in situ nasal and intestinal perfusion techniques and utilized sodium glycocholate (NaGC), three acylcarnitines, and their mixed micelles as potential nasal and intestinal absorption promoters. Acylcarnitines used were DL-octanoylcarnitine chloride (OCC), palmitoyl-DL-carnitine chloride (PCC), and DL-stearoylcarnitine chloride (SCC). All acylcarnitines and NaGC by themselves produced negligible enhancement of acyclovir absorption in the rat intestine, while OCC and SCC were totally ineffective in the nasal cavity. However, the mixed micellar solutions of NaGC with PCC or SCC could significantly increase the mucosal membrane permeability of acyclovir in the colon and nasal cavity. On the other hand, NaGC-OCC mixed micelles slightly increased the absorption of acyclovir by both routes. When a mixed micellar solution of NaGC with PCC was used, the rank order of apparent acyclovir permeability (Papp; cm/sec), corrected for surface area of absorption, was N (10.54 +/- 0.62 x 10(-5)) > D (6.82 +/- 0.30 x 10(-5)) > LJ (2.90 +/- 0.08 x 10(-5)) > C (2.54 +/- 0.14 x 10(-5)) > UJ (2.30 +/- 0.22 x 10(-5)).(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed1992

Mechanism and site dependency of intestinal mucosal transport and metabolism of thymidine analogues.

This study has been undertaken to investigate the mechanisms of intestinal mucosal transport and metabolism of thymidine analogues and to identify any optimal site(s) of the rat intestine particularly involved in the absorption of thymidine analogues. The intestinal absorption of 3'-azido-3'-deoxythymidine (AZT) was studied at three initial concentrations in four segments of the rat intestine using an in situ recirculating perfusion technique. Disappearance of AZT followed first-order kinetics throughout the gastrointestinal (GI) tract at all tested concentrations. The apparent first-order rate constants were found to be relatively invariant over a broad range of concentrations from 0.01 to 1.0 mM. Corrected for the length of each segment, the apparent permeability (Papp) of AZT was 3.01 +/- 0.32 x 10(-5) cm/sec (mean +/- SE) in the duodenum, 2.06 +/- 0.24 x 10(-5) cm/sec in the upper jejunum, 0.76 +/- 0.13 x 10(-5) cm/sec in the combined lower jejunum and ileum, and 0.32 +/- 0.10 x 10(-5) cm/sec in the colon, which indicated that intrinsic absorptivity was greater in the upper GI tract than in the lower portions possibly due to the differences in surface area for absorption. No AZT metabolite appeared in any part of the GI tract. On the other hand, thymidine and other analogues, i.e., 5-iodo-2'-deoxyuridine and 2'-deoxyuridine, were rapidly metabolized into nucleobase and sugar in the upper GI tract, whereas in the colon no metabolite appeared. A free 3'-OH group appears to be necessary for the metabolism (catabolism) of thymidine analogues in the rat intestine mainly by pyrimidine nucleoside phosphorylase.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Relative bioavailability and pharmacokinetics: a combination of pentazocine and acetaminophen.

The relative bioavailability and pharmacokinetics of a combination product containing pentazocine and acetaminophen were studied in 20 healthy human males. Each subject, in a single-dose three-way crossover design, received two different preparations containing 50 mg of pentazocine (as base) and 1300 mg of acetaminophen either as capsule-shaped tablets or as a solution. Plasma concentrations of pentazocine and acetaminophen were determined from 0.25 to 12 h following oral administration. The plasma data for both compounds in the tablet formulation were described by an open one-compartment body model with first-order absorption. The average (+/- SD) bioavailability of the tablet relative to that of the solution was 85.0 +/- 31.1 and 88.6 +/- 13.1% for pentazocine and acetaminophen, respectively. The apparent first-order regression-dependent elimination rate constants for pentazocine from the tablet and solution preparations were 0.19 +/- 0.08 and 0.20 +/- 0.06 h-1, respectively, while the rate constants for acetaminophen were 0.26 +/- 0.03 and 0.25 +/- 0.03 h-1 for the tablet and solution preparations, respectively. These rate constants correspond to terminal elimination half-lives of approximately 3.6 h for pentazocine and approximately 2.7 h for acetaminophen.

Acetaminophen↗
PubMed1983

Oral bioavailability and intravenous pharmacokinetics of amrinone in humans.

Fourteen healthy males received two 75-mg doses of amrinone as a single capsule and as an intravenous solution in a single-dose crossover study. The mean (+/-SD) bioavailability, based on the area under the plasma concentration versus time curves, was 0.93 +/- 0.12. The plasma data for these subjects during the intravenous phase was described by an open two-compartment body model with a mean (+/-SD) apparent first-order terminal elimination rate constant, beta, of 0.19 +/- 0.06 hr-1, which corresponds to a half-life of 3.6 hr.

Administration, Oral↗
PubMed1983

Dose proportionality of amrinone.

Amrinone was given to 18 healthy subjects in doses of 75, 150, and 225 mg in a randomized crossover design. Plasma levels were shown to rise in proportion to dose. The mean plasma AUC, extrapolated to infinite time, was determined for each dose level; the values obtained were 4, 8.18, and 12.35 micrograms . hr/ml for the 75-, 150-, and 225-mg doses. Mean maximum observed plasma concentrations were 1.03, 1.74, and 2.58 micrograms/ml. At higher doses the extrapolated AUC is more variable, but it is linear over the range of 0.73 to 3.81 mg/kg. The apparent first-order terminal elimination rate is not dose dependent and corresponds to a t1/2 of 3.85 hr.

Adult↗
PubMed1982

Pharmacokinetics of rosoxacin in human volunteers.

Reversed-phase liquid chromatography was used to determine plasma rosoxacin concentrations in normal, healthy males, each of whom received one 300 mg capsule of rosoxacin. The plasma data for each subject were described by an open one-compartment body model with first-order absorption, and the pharmacokinetic parameters were determined. The mean (+/- SE) apparent first-order terminal elimination rate constant was 0.203 +/- 0.015 hr-1 (N = 16), the mean apparent volume of distribution was 0.644 +/- 0.050 liters/kg, and the mean apparent plasma clearance was 2.08 +/- 0.15 ml/min/kg.

4-Quinolones↗
PubMed1982

Determination of isoetharine in plasma by reversed-phase chromatography with amperometric detection.

A reversed-phase liquid chromatographic method for the determination of isoetharine in blood plasma, utilizing amperometric detection, is described. Plasma samples were extracted utilizing an ion-pair reagent, di-(2-ethylhexyl)phosphoric acid, to concentrate the catecholamine. Only minor differences were observed in the relative bioavailability of isoetharine hydrochloride and isoetharine mesylate after oral administration to rats. Observed plasma levels, at 1 hr after oral medication, were highly variable in dose-ranging studies at doses of 800-2500 mg/kg/day for 2 weeks.

Administration, Oral↗
PubMed1982

The pharmacokinetics and pharmacodynamics of sulfinalol hydrochloride in dogs after intravenous administration.

The pharmacokinetic behavior of sulfinalol hydrochloride, an antihypertensive agent with vasodilator and beta-adrenergic blocking activity, was determined in dogs after intravenous administration. The plasma concentrations of sulfinalol HCl were fit to an open two-compartment body model. The mean values for the alpha- and beta-phase constants were 33.3 hr-1 and 0.52 hr-1, respectively. The mean plasma clearance was 2.30 L/kg X hr. The steady-state volume of distribution was approximately four times the body weight of the animals. The urine data gave renal clearance rates approximately equal to the normal glomerular filtration rate in the dog. About 7.5% of the administered dose was excreted in the urine as free sulfinalol hydrochloride. The time course of the hypotensive effect of sulfinalol appears to be better correlated with calculated tissue levels of drug than with observed plasma levels.

Adrenergic beta-Antagonists↗
PubMed1981

The analysis of arildone in plasma, urine and feces by gas--liquid chromatography with electron-capture detection.

The analysis of arildone in plasma, urine and feces by gas--liquid chromatography with electron-capture detection is described. O-(2,3,4,5,6-Pentafluorobenzyl)hydroxylamine is the derivatizing agent for the plasma and urine analysis; 3-nitrophenylhydrazine is utilized for fecal analysis. The mean (+/- S.E.) minimum quantifiable level of arildone was 1.4 (+/- .02) ng/ml in urine, 6.4 (+/- 0.1) ng/ml in plasma, and 12.6 (+/- 1.0) ng/g in feces. The chromatographic response was linear in the range of 0 and 10--120 ng/ml for plasma, 0 and 2.5--20 ng/ml for urine and 0 and 25-250 ng/g for feces. The estimated overall precision of the assay was 5.5%, 64% and 8.9% in urine, plasma and feces, respectively.

Antiviral Agents↗
PubMed1980

Analysis of mepivacaine, bupivacaine, etidocaine, lidocaine, and tetracaine.

A GLC method, employing a nitrogen-phosphorus-sensitive detector, is described for the analysis of mepivacaine, bupivacaine, etidocaine, lidocaine, and tetracaine in biological fluids. The method is simple, reliable, and sensitive, with a practical limit of sensitivity of approximately 2.5 ng/ml, well below therapeutic plasma levels. Extensive start-up procedures and sample preparation are not required.

Acetanilides↗