• YAKHAK HOEJI
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• v.24 no.1
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• pp.11-14
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• 1980

In order to increase the gastro-intestinal absorption of cephalexin, a new cephalexin phthalidyl ester was synthetized. Comparative studies of cephalexin phthalidyl ester in the gastro-intestinal absorption were conducted after oral administration in rabbits. The amounts of cephalexin in plasma were determined by a fluorometric method. Cephalexin phthalexin phthalidyl ester could not be identified in plasma, but only cephalexin was found by TLC method. In comparison with cephalexin, cephalexin phthalidyl ester produced much higher plasma levels of cephalexin than did cephalexin itself after its oral administration in rabbits.

• Korean Journal of Veterinary Research
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• v.32 no.2
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• pp.251-258
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• 1992

Liposomal cephalexin was used m the dry period treatment of bovine mastitis due to Staphylococcus aureus. Liposomes were prepared by stable plurilamellar vesicle(SPLV) process. The shape and size of SPLVs were examined by transmission electron microscopy. The entrapping efficiency and stability of SPLVs were determined by high performance liquid chromatography or liquid scintillation counting. The size of SPLVs ranged from 0.1 to $4.01{\mu}m$ in diameter, with an entrapping efficiency of cephalexin of 25.8 %. The formulation of liposomal cephalexin was used for treatment were SPLV-entrapped cephalexin and free cephalexin with total cephalexin concentration of 250mg per quarters. All quarters were infused intramammarily at the end of lactation period by liposomal cephalexin, free cephalexin, or blank liposome with free cephalexin. The number of quarters cured by liposomal cephalexin(14/15 quarters, 93 %) was significantly higher than that by free cephalexin(7/15 quarters, 46%). or by blank liposome with free cephalexin(8/15 quarters, 53 % ) (p<0.05).

• Journal of Veterinary Clinics
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• v.19 no.2
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• pp.228-235
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• 2002

Mastitis is the most costly disease results in lost milk production, decreased milk quality, milk discard, early culling of cows, drug costs and labor costs in dairy cow. Until now, a antibiotic administration at the end of lactation, dry cow therapy has been known the most effective and widely used mastitis control method. However, dry cow therapy do not control a new infection in the late dry and prepartum period because dry cow products have only persistent activity in the early dry period. Therefore, this study was conducted to evaluate clinical effect of sustained released biodegradable cephalexin microsphere using PLGA in bovine mastitis control during dry period. PLGA has been approved as controlled drug release system because of non-toxic, non-tissue reactive and bioerodible characteristics. This study revealed that cephalexin microsphere had a spherical shape with characteristic porous structure on the surface. Also, in vitro drug release studies are clearly observed that the release rate of cephalexin from PLGA microsphere decrease during the first 21 days after initial burst and then increase again between 3 and 4 weeks showing pulsatile releasing pattern. On the other hand, as tried in field the new infection rate, cure rate and mean SCC after parturition in cephalexin microsphere infused group were significantly differenced as compared to the control group. Accordingly, a sustained release of cephalexin from a biodegradable microsphere could make dry cow therapy more efficiently by preventing a new infection and decreasing the number of existing infection of mammary gland during dry period.

• Molecular & Cellular Toxicology
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• v.2 no.3
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• pp.193-201
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• 2006

Cephalexin, one of most widely prescribed cephalosporin, has been reported to cause acute renal failure as a side effect in human and experimental animals. Although numerous animal studies have been reported for the cephalosporin nephrotoxicity, the molecular and cellular nephrotoxic mechanisms of cephalexin are still unknown. This investigation evaluated the time-dependent gene expression profile of kidney in mouse during cephalexin induced nephrotoxicity. C57BL/6 female mice were administered either saline or 1,000 mg/kg cephalexin intraperitoneally. Mice were sacrificed at 3, 6, and 24 hr after administration. Blood biochemical and histopathological results indicated cephalexin induced nephrotoxicity. Microarray experiment carried out using Affymetrix $GeneChip^{(R)}$. There were 198 informative genes that were significantly expressed >5-fold versus control at 3, 6, and 24 hr (p<0.01), of which 156 and 42 were up-and down-regulated, respectively. Major classes of up-regulated genes at 3, 6 hr included those involved in MAPK/Jak-STAT signaling pathway and immune response such as cytokine-cytokine receptor interaction and complement and coagulation cascades. At 24 hr, up-regulated genes were mainly involved in regeneration/repair and immune response; down-regulated genes were generally associated with transporters and intermediary metabolism. Among the up-regulated genes at 24 hr, several potential biomarkers on nephrotoxicity such as Kim-1, Fga, Timp1, and Slc34a2 were clustered in a same category. In addition, Tnfrsf12a and Lcn2 which were consistently up-regulated (>5 fold) were also included as potential biomarkers. These results may provide clues for elucidating the mechanism of cephalexin induced nephrotoxicity and evaluating potential biomarkers to assess nephrotoxicity.

• Korean Journal of Veterinary Research
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• v.43 no.3
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• pp.435-438
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• 2003

The objective of this study was to investigate the residue depletion of cephaalexin in the flounder (Paralichthys olivaceus) after multiple oral administrations and to establish the appropriate withdrawal time for edible tissues. A highly sensitive and specific method for the determination of cephalexin in the serum of flounder by LC/MS was developed and validated. Mean recoveries from serum were 87.2% (ranged from 81.2% to 94.5%) for cepalexin. Recovery and precision met the criteria for the guideline of residual analysis of veterinary drugs by the National Veterinary Research and Quarantine Service (NVRQS) in Korea. The limit of detection and limit of quantitation of cephalexin were 10 ng/ml and 50 ng/ml, respectively. Residual levels of cephalexin in muscle samples were estimated with 95% tolerance limit and 95% confidence to fall below the MRL after a withdrawal time of 4 days and 5 days for the 40 and 160 mg/kg/day, respectively.

• Journal of Microbiology and Biotechnology
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• v.11 no.2
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• pp.329-332
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• 2001

It has been known that, in enzymatic synthesis of cephalexin, the conversion yield was reduced by high loading of ampicillin acylase. In order to elucidate this phenomena, pH-controlled synthesis of cephalexin was examined using a purified Acetobacter turbidans acylase. When the pH of the reaction mixture was maintained at $6.20{\pm}0.04$, the reduction of the maximal conversion rate was not observed even with high enzyme loading. The kinetic parameters also suggest that pH drop during the enzymatic synthesis of cephalexin was mainly attributed to the rapid hydrolysis of D-${\alpha}$-phenylglycine methyl ester to D-${\alpha}$-phenylglycine, rather than the disappearance of 7-amino-3-deacetoxycephalosporanic acid for cephalexin synthesis. At higher molar ratio of two substrates, [D-${\alpha}$-phenylglycine methyl ester]/[7-amino-3-deacetoxycephalosporanic acid], the conversion rate was also elevated under pH-controlled enzymatic synthesis, which implies that the main reason for the pH drop is due to the production of D-${\alpha}$-phenylglycine methyl easter, the effect of a water-methanol cosolvent system on the ester, the effect of a water-methanol cosolvent system on the conversion profile was also examined. Even the though the conversion rate was increased in 10% methanol solution, a higher than 16% methanol in the reaction mixture caused an inactivation of enzyme.

• Journal of Microbiology and Biotechnology
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• v.14 no.1
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• pp.62-67
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• 2004

The biosynthesis of cephalexin was carried out in the aqueous two-phase systems using penicillin acylase as a catalyst, and 7-aminodeacetoxicephalosporanic acid (7-ADCA) and phenylglycine methyl ester (PGME) as substrates. 20% PEG400-l7.5% ${(NH_4)}_2SO_4$ containing 0.5 M NaCl and 1.5 M methanol aqueous two-phase systems (ATPS) were selected as reaction medium, and 53% product yield was obtained using immobilized penicillin acylase as a catalyst. 20% PEG400-l5% $MgSO_4$ ATPS was also used for the synthesis of cephalexin, and 60-62% product yield was obtained by using free penicillin acylase as a catalyst. When batch reactions were repeated in the ATPS, the cephalexin yields decreased during the reactions due to deactivation, loss, and product inhibition of penicillin acylase. The effect of different ratio of phenylglycine methyl ester to 7-ADCA on the product yield was investigated, and high cephalexin yield was obtained at a high molar ratio.

• Journal of Pharmaceutical Investigation
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• v.23 no.2
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• pp.103-110
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• 1993

Microcapsules(Mc) of cephalexin (CEPH), using Eudragit RS, RL, L, S and polyethylene glycol 1540, were evaluated biopharmaceutically. The area under the curve of CEPH-Eudragit RS/RL Mc administered orally once was larger than that of cephalexin powder twice every 6 hrs. Controlledrelease effectiveness and the absorption rate effectiveness, two important parameters of Vallner's method, of CEPH-Eudragit RS/RL Mc indicate that these Mc can be good sustained-release preparations. And a simple pharmacokinetic model is introduced which allows the gastric emptying and intestinal-transit rates of a drug itself and a solid-state drug contained in Mc. Decreasing $K_r$, without change in $K_a$, showed that the rate-limiting step of absorption moved from absorption step to releasestep.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1986.12a
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• pp.525.2-525
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• 1986

Cephalexin synthesizing enzyme (${\alpha}$ amino acid ester hydrolase) was partially purified from the culture broth of Acetobacter turbidans ATCC9325 through ammonium sulfate fractionation, DEAE, CM, and Sephacryl S-200 gel filtration. The enzyme has optimum pH 6.0 and temperature, 40$^{\circ}C$ respectively. From the analysis of reaction mixtures by thin layer chromatographic and high performance liquid chromatographic techniques, it was confirmed this enzyme catalyzed simultaneously the following reactions : 1) Synthesis of cephalexin from D-${\alpha}$-phenylglycine methylester (PGM) and 7-amino 3-deacetoxy-cetoxycephalosporanic acid (7-ADCA) 2) Hydrolysis of cephalexin to form 7-ADCA and phenylglycine (PG) 3) Hydrolysis of PGM to form PG and methanol. Base on the above experimental observations, the reaction model of this enzyme was identical with that of the enzyme from Xanthomonas citri.

• YAKHAK HOEJI
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• v.20 no.1
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• pp.32-36
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• 1976

The pH titration curves of ampicillin, amoxicillin and cephalexin in aqueous acetone, ethanol and N, N'-dimethylformamide by use of 0.02N-KOH solution showed that 80% acetone was the most effective solvent for alkali titration of them. The pH jumps of samples in 80% acetone were sharp enough to determine the contents of them by use in 80% acetone (9, 4) was coincided with each equivalent point of ampicillin, amoxicillin and cephalexin, but those of phenolphthalein, thymolphthalein, thymol blue and bgrom cresol purple were not. The color change of brom thymol blue at equivalent points was very clear except the case of amoxicillin that the determination of smaples in 80% acetone with 0.02 N-KOH solution by the aid of brom thymol blue could be available.