• Journal of Microbiology and Biotechnology
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• v.29 no.3
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• pp.367-372
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• 2019

Deactivation of aminoglycosides by their modifying enzymes, including a number of aminoglycoside O-phosphotransferases, is the most ubiquitous resistance mechanism in aminoglycoside-resistant pathogens. Nonetheless, in a couple of biosynthetic pathways for gentamicins, fortimicins, and istamycins, phosphorylation of aminoglycosides seems to be a unique and initial step for the creation of a natural defensive structural feature such as a 3',4'-dideoxy scaffold. Our aim was to elucidate the biochemical details on the beginning of these C3',4'-dideoxygenation biosynthetic steps for aminoglycosides. The biosynthesis of istamycins must surely involve these 3',4'-didehydroxylation steps, but much less has been reported in terms of characterization of istamycin biosynthetic genes, especially about the phosphotransferase-encoding gene. In the disruption and complementation experiments pointing to a putative gene, istP, in the genome of wild-type Streptomyces tenjimariensis, the function of the istP gene was proved here to be a phosphotransferase. Next, an in-frame deletion of a known phosphotransferase-encoding gene forP from the genome of wild-type Micromonospora olivasterospora resulted in the appearance of a hitherto unidentified fortimicin shunt product, namely 3-O-methyl-FOR-KK1, whereas complementation of forP restored the natural fortimicin metabolite profiles. The bilateral complementation of an istP gene (or forP) in the ${\Delta}forP$ mutant (or ${\Delta}istP$ mutant strain) successfully restored the biosynthesis of 3',4'-dideoxy fortimicins and istamycins, thus clearly indicating that they are interchangeable launchers of the biosynthesis of 3',4'-dideoxy types of 1,4-diaminocyclitol antibiotics.

• Korean Journal of Clinical Pharmacy
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• v.6 no.2
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• pp.28-31
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• 1996

The in vitro inactivation of gentamicin and tobramycin by four cephalosporins (cefotetan, cefuroxime, cefodizime, cefotiam) in human serum was investigated. Each cephalosporin was added to human serum samples containing gentamicin sulfate or tobramycin sulfate. Blank samples containing only aminoglycosides were used as controls. Samples were stored at -20, 4 and $25^{\circ}C$ and were analyzed for aminoglycoside concentrations by fluorescence polarization immunoassay ($TDxFLx^{TM}$ system) at 0, 2, 4, 8, 12, 24, 48 and 72 hours after mixing. The serum containing cefotiam stored at $25^{\circ}C$ showed significant inactivation of gentamicin by $12\%$ at 72 hours. The results indicate that cefotitan, cefuroxime and cefodizime do not inactivate gentamicin and tobramycin while cefotiam inactivates gentamicin.

• Toxicological Research
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• v.13 no.1_2
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• pp.61-69
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• 1997

Exposure of splenocytes to 2-chloroethylethyl sulfide (CEES) resulted in the cell death, and the cytotoxicity of CEES was prevented by inhibitors of lysosomal hydrolases. Therefore, it has been postulated that the cytotoxicity of CEES may be partially due to the lysosomal labilization. This study, based on this mechanism, was undertaken to determine whether aminoglycoside antibiotics as inhibitors of lysosomal phospholipases and their combinations with other lysosome stabilizers can be useful as a treatment to reduce the CEES toxicity in mice. 2-Chloroethylethyl sulfide (20 mg/kg body weight) was injected ip into female ICR mice, and candidate compounds were administered ip before or after the CEES challenge. Kanamycin (40 mg/kg body weight) as effective as deferoxamine (100 mg/kg body weight) enhanced the survival rate after 5 days of intoxication from 10% of control to 50 - 60%. The most effective was found to be the combination of kanamycin, cycloheximide, deferoxamine and dextrose showing an almost full protection against 2LD50 of CEES. Consistent with the protection of the CEES toxicity, the decrease of body weight in mice intoxicated with CEES was effectively prevented by kanamycin or its combinations. It is suggested that kanamycin or its combination (kanamycin, cycloheximide, deferoxamine and dextrose) would be one of effective antidotes against the CEES poisoning in mice.

• Journal of Veterinary Clinics
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• v.27 no.2
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• pp.125-129
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• 2010

A 2-year-old female Pomeranian dog was referred with multiple pelvic fractures. The surgical correction was performed for the fractures. However, after the surgery, purulent exudation was occurred in the surgical site. Antibiotic susceptibility test revealed that the isolated bacteria are resistant to penicillins, cephalosporins, aminoglycosides, quinolones, and trimethoprim/sulfamethoxazole. Bacterial identification and extended-spectrum $\beta$-lactamase (ESBL) confirming test indicated that the isolated bacteriae is ESBL-producing Klebsiella pneumoniae. Minimum inhibitory concentration (MIC) and maximum bactericidal concentration (MBC) tests revealed that meropenem, one of carbapenems, is the only effective antibiotic. The patient was treated with meropenem for 5 days. After 10 days, the exudation was disappeared and the infection was cured. The molecular typing of the ESBL revealed that TEM-1 ESBL is present in the bacteria isolated from the patient. The bacteria isolated from the owner's palm also revealed that TEM-1 and SHV-1 ESBLs are present.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.10
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• pp.1498-1504
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• 2005

Competitive direct ELISA was developed to detect gentamicin residues. Mice immunized with gentamicin-keyhole limpet hemocyanin (KLH) conjugate developed good antiserum titers, which gradually increased with booster injections, indicating immunization was successfully processed. Monoclonal antibody against gentamicin was prepared using hybridoma cells cloned by limit dilution of fused cells. IgG was purified from ascites fluid of hybridoma cell-injected mice through ammonium sulfate precipitation and Sephadex G-25 gel filtration. After the gel filtration, fractions of high antibody titer were further purified through affinity chromatography on protein A/G column. Monoclonal antibody against gentamicin was confirmed as IgG1, which has kappa light chain. Cross-reactivities ($CR_{50}$) of gentamicin monoclonal antibody to other aminoglycosides (kanamycin, neomycin, and streptomycin) were less than 0.005%, indicating the monoclonal antibody was highly specific for gentamicin. Standard curve constructed through competitive direct ELISA showed measurement range (from 80 to 20% of B/$B_0$ ratio) of gentamicin was between 1 and 40 ng/ml, and 50% of B/$B_0$ ratio was about 4 ng/ml. The gentamicin concentration rapidly increased to 1,300 ng/ml after the intramuscular administration up to 2 h, then sharply decreased to less than 300 ng/ml after 4 h of withdrawal, during which the elimination half-life ($t_{1/2}$) of gentamicin in the rabbit plasma was estimated to be 1.8 h. Competitive direct ELISA method developed in this study using the prepared monoclonal antibody is highly sensitive for gentamicin, and could be useful for detecting gentamicin residues in plasma of live animals.

• Journal of Microbiology and Biotechnology
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• v.17 no.12
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• pp.1909-1921
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• 2007

Significant progress has recently been made concerning the engineering of deoxysugar biosynthesis. The biosynthetic gene clusters of several deoxysugars from various polyketides and aminoglycosides-producing microorganisms have been cloned and studied. This review introduces the biosynthetic pathways of several deoxysugars and the generation of novel hybrid macrolide antibiotics via the coexpression of deoxysugar biosynthetic gene cassettes and the substrate-flexible glycosyltransferases in a host organism as well as the production of TDP-deoxysugar derivatives via one-pot enzymatic reactions with the identified enzymes. These recent developments in the engineering of deoxysugars biosynthesis may pave the way to create novel secondary metabolites with potential biological activities.

• Korean Journal of Clinical Pharmacy
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• v.16 no.2
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• pp.81-85
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• 2006

Community acquired pneumonia(CAP) is the most prevalent disease among pneumonia patients and progressed to severe pneumonia. A retrospective study was performed to evaluate antibiotic regimens according to guidelines of Infectious Disease Society of America. From January to October 2005, chart review of 50 patients with CAP was peformed in terms of microbiology and laboratory data of each regimen. Temperature, WBC count, ALT, AST and alkaline phosphatase of each patient were examined for liver toxicity. In three patients received levofloxacin appeared to have normalized temperature and improved cough. The patients who received cefmetazole -aminoglycoside appeared to have worsen LFT(Liver function test). Many patients in flomoxef-aminoglycoside group received mechanical ventilation because of the basis diseases like tuberculosis, diabetes mellitus and hypertension. In conclusion, antibiotic therapy for the treatment of CAP should be selected according to tolerance, bacteria and severity of disease.

• Journal of Food Hygiene and Safety
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• v.11 no.4
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• pp.307-314
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• 1996

The European Economic Community four plate test(EEC 4-plate test, FPT, EU) has been used for monitoring antimicrobial drug residues in meat by Local Veterinary Service Center in Korea. This study was performed to evaluate sensitivity and group specificity of some antimicrobial drugs in FPT and to compare FPT with Charm II test. The minimal detectable levels of targeted antimicrobial drugs tested with standard solutions were 0.025∼1.0 ppm for 7 beta-lactams, 0.5∼1.0 ppm for 4 aminoglycosides, 0.05∼0.5 ppm for 5 macrolides, 0.05∼0.25 ppm for 3 tetracyclines and 0.25&1.0 ppm for 6 sulfonamides. In comparison of FPT and Charm II test, the results of FPT were not accord with those of Charm II test having the group specificity of seven families of antimicrobial drugs in meat samples except some families like tetracyclines.

• Journal of Korean Biological Nursing Science
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• v.8 no.1
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• pp.5-14
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• 2006

Staphyloccus aureus is one of the most important pathogens in clinical settings. It is also one of the leading causes of nosocomial infections and the dissemination of multiple drug-resistant strains, mainly methicillin resistant Staphyloccus aureus, and the recent emergence of a vancomycin resistant MRSA is the concern to hospital worldwide. MRSA strains have acquired multiple resistance to a wide range of antibiotics, including aminoglycosides and macrolides. $\beta$-Lactam resistance of methicillin-resistnat Staphyococcus aureus is determined by the function of penicillin binding protein 2'(PBP2') encoded by the methicillin resistance gene mec A. MRSA strains carry methicillin resistance gene mecA, encoded by a mobile genetic element designated staphylococoal cassette chromosome mec(SCCmec). MRSA clones are defined by the type of SCCmec element and the genotype of the methicilline-susceptible Staphyococcus aureus chromosome in which the SCCmec element is integrated.

• Journal of Microbiology and Biotechnology
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• v.15 no.2
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• pp.421-424
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• 2005

Effect of antibiotics belonging to three different groups, including third generation cephalosporins, aminoglycosides, and quinolones, on the outer membrane protein (OMP) profile of Klebsiella pneumoniae was examined. It was found that a new OMP (porins) of 40 kDa molecular mass was expressed in Klebsiella pneumoniae, when grown in the presence of ceftazidime, whereas new proteins with 30 kDa and 22 kDa masses were detected in the presence of ofloxacin. The immunoblot analysis showed that the new proteins of 40 kDa and 30 kDa molecular masses were expressed on the outer envelope, when being exposed to antibiotics ceftazidime and ofloxacin, respectively. This finding is important, as the outer surface comes in contact with the immune system, and therefore may have a bearing on the outcome of the disease.