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Biomedical subjects

Y Chong

Publications and source records attributed to Y Chong.

At least 55 records · Page 3Linked to original sources
PubMed1998

Nocardia osteomyelitis in a pachymeningitis patient: an example of a difficult case to treat with antimicrobial agents.

Antimicrobial agents played a miraculous role in the treatment of bacterial infections until resistant bacteria became widespread. Besides antimicrobial-resistant bacteria, many factors can influence the cure of infection. Nocardia infection may be a good example which is difficult to cure with antimicrobial agents alone. A 66-year-old man developed soft tissue infection of the right buttock and thigh. He was given prednisolone and azathioprine for pachymeningitis 3 months prior to admission. Despite surgical and antimicrobial treatment (sulfamethoxazole-trimethoprim), the infection spread to the femur and osteomyelitis developed. The case showed that treatment of bacterial infection is not always as successful as was once thought because recent isolates of bacteria are more often resistant to various antimicrobial agents, intracellular parasites are difficult to eliminate even with the active drug in vitro, and infections in some sites such as bone are refractory to treatment especially when the patient is in a compromised state. In conclusion, for the treatment of infections, clinicians need to rely on laboratory tests more than before and have to consider the influence of various host factors.

Aged↗
PubMed1998

Syncope in a 65-year-old woman after nitrate ingestion.

A 65-year-old woman with angina pectoris presented with syncope after sublingual ingestion of isosorbide dinitrate (5 mg). Her response to a postural challenge test, without medication, was normal. In a postural challenge test after administration of isosorbide dinitrate (5 mg), blood pressure decreased from 120/67 to 65/35 mmHg, followed by syncope with a sudden decrease in pulse rate from 85 to 60 beats/min. No evidence of myocardial infarction was detected. Elderly patients for whom nitrate has been prescribed should be warned of the occurrence of hypotension, leading to unconsciousness.

Administration, Sublingual↗
PubMed1997

Effect of a carboxy-terminal fragment of the Alzheimer's amyloid precursor protein on expression of proinflammatory cytokines in rat glial cells.

To explore factors involved in the induction of cytokines that may contribute to the pathogenesis of Alzheimer's disease (AD), the effect of a carboxy terminal 105 amino acid fragment (CT105) of the amyloid precursor protein (APP) on the gene expression of proinflammatory cytokines, IL-1beta and IL-6 was determined in cultured rat cortical glial cells in comparision to amyloid beta protein (A beta). Cells were incubated with 1 microM of insoluble CT105 aggregates or aged A beta1-40 peptide deposits which were mainly composed of stable monomeric and dimeric forms as assessed on Western blots. The levels of mRNAs were analyzed by reverse transcription polymerase chain reaction (RT-PCR). Highest levels of both IL-1beta and IL-6 transcripts were detected in the culture exposed to CT105 aggregates for 4 days. CT105 aggregates markedly increased IL-1beta mRNA level by 3.5 fold of the control level and this effect was more potent than that produced by aged A beta1-40 peptides. Furthermore, CT105 strongly induced accumulation of IL-6 mRNA level by 2 fold of the value potentiated by A beta1-40. Such induction was not observed with A beta 12-28 treatment. On the other hand, CT105 did not significantly alter either APP or glial fibrillary acidic protein (GFAP) mRNA levels. These results together imply that CT peptide besides its cytotoxic potency may act as a potent immunological component, strongly inducing both IL-1beta and IL-6 mRNA levels in the cultured glial cells. This CT peptide associated exacerbation of cytokine expression may be in part responsible for chronic inflammation linked to slowly progressive neurodegeneration characteristic to AD.

Amyloid beta-Protein Precursor↗
PubMed1997

Spread of the serotype 23F multidrug-resistant Streptococcus pneumoniae clone to South Korea.

Thirty-eight antibiotic-resistant isolates of Streptococcus pneumoniae recovered in a hospital in Seoul, Korea, between February 1990 and March 1992 were analyzed for serotype, antibiotic susceptibility patterns, and chromosomal relatedness using pulsed-field gel electrophoretic (PFGE) analysis of SmaI chromosomal digests. Most of the isolates were from sputum samples, and a few strains were from otitis media and meningitis. The great majority of isolates (34 of 38, or 89%) were multiresistant, sharing virtually identical, elevated minimal inhibitory concentration (MIC) values (microgram/ml) for penicillin (1-2), chloramphenicol (12-25), tetracycline (25-30), and sulfamethoxazole/trimethoprim (> 100). Twenty of the isolates were also resistant to erythromycin, and all isolates were also considered to be resistant to ceftriaxone and cefotaxime (1-2) according to the new breakpoint definitions. The most frequent serotypes were 23F (17 of 38) and 19F(14 of 38); 2 belonged to serotype 15B and 1 of 24F. Of the remaining 4 isolates (2 serotype 3, 1 type 6B, and 1 type 9V) all were resistant to tetracycline and sulfamethoxazole/trimethoprim and with the exception of 1 of the type 3 strains, were also resistant to chloramphenicol. Eleven of the 14 serotype 19F isolates shared a relatively homogeneous PFGE pattern, which was indistinguishable from the PFGE pattern shown by most (12 of 17) of the 23F isolates. The PFGE pattern of these 19F and 23F isolates was also indistinguishable from the PFGE pattern shown by representative multiresistant capsular type 23F isolates from Croatia, Portugal, and New York City and the findings document the extensive geographic spread of this multidrug-resistant S. pneumoniae clone. The data also suggests in vivo capsular transformation of the multiresistant clone from serotype 23F to serotype 19F.

DNA Fingerprinting↗
PubMed1996

Emerging resistance of anaerobic bacteria to antimicrobial agents in South Korea.

In previous studies, Bacteroides fragilis group organisms isolated from Korean patients were more frequently resistant to various antimicrobial agents, including clindamycin, than were isolates in other countries. A recent report of increased resistance of Peptostreptococcus species prompted us to include such isolates in a study of antimicrobial susceptibility. anaerobes isolated in 1994 at a tertiary care hospital in Seoul were tested by agar dilution method. None of the B. fragilis group organisms were resistant to imipenem, cefoxitin, chloramphenicol, or metronidazole. However, 6.7% were resistant to ampicillin/sulbactam, 20.2% to cefotetan, 30.3% to piperacillin, 48.3% to cefotaxime, and 42.7% to clindamycin. Almost all of the Clostridium perfringens isolates were susceptible to all of the agents tested, except tetracycline. Peptostreptococcus isolates were susceptible to piperacillin, cefotaxime, and imipenem, while 7.4% were resistant to penicillin G, cefotetan, and metronidazole, and 25.9% were resistant to clindamycin. The isolates resistant to penicillin G, cefotetan, and metronidazole were identified as Peptostreptococcus anaerobius. In conclusion, besides the well-known high rate of resistance of B. fragilis group organisms to clindamycin, the emergence of resistance of Peptostreptococcus species isolates to beta-lactam drugs has become obvious in Korea.

Anti-Bacterial Agents↗
PubMed1996

Comparative characterization of the cephamycinase blaCMY-1 gene and its relationship with other beta-lactamase genes.

A plasmidic beta-lactamase which hydrolyzed cephamycins was first detected and reported in 1989. At that time its description was restricted to phenotypic characteristics. We analyzed nucleotide sequence of its gene and explored it genetic relationship with other bla genes. The deduced amino acid sequence of the blaCMY-1 product was compared with those of other known plasmidic cephamycinases and of chromosomal AmpC beta-lactamases. The results indicate that the relationship of CMY-1 is closest to MOX-1 among the plasmidic cephamycinases and to AmpC of Pseudomonas aeruginosa among the chromosomal cephalosporinases. We conclude that the plasmidic cephamycinases described up to now may be classified into three families, as follows: CMY-1, MOX-1, and FOX-1 with AmpC of P. aeruginosa; CMY-2, BIL-1 and LAT-1 with AmpC of Citrobacter freundii; and MIR-1 with AmpC of Enterobacter cloacae. Plasmidic cephamycinases are now recognized as clinically relevant class C beta-lactamases.

Amino Acid Sequence↗
PubMed1996

Acculturation and low-birthweight infants among Latino women: a reanalysis of HHANES data with structural equation models.

Previous studies have demonstrated that acculturation is associated with negative birth outcomes among mothers in numerous immigrant populations, including Latinas. This study used structural equation models to reanalyze data employed in the 1989 Scribner and Dwyer study on the effect of acculturation (measured through the Cuellar scale) on mothers' low-birthweight status. Data revealed that language components dominate the effects of acculturation on low-birthweight status. Acculturuation appears to affect low-birthweight status indirectly through smoking and dietary intake but not through parity. Acculturation has a persistent direct effect on low-birthweight status, suggesting that other intervening variables are operant.

Acculturation↗
PubMed1995

Capsular types and antimicrobial resistance of Streptococcus pneumoniae isolated in Korea.

The capsular types and the MICs of penicillin G and other antimicrobial agents were determined for 89 isolates of Streptococcus pneumoniae. MICs of penicillin G ranged from 0.015 to 2 mg/l, with 29% and 48% of the isolates exhibiting intermediate resistance and complete resistance, respectively. All isolates were susceptible to teicoplanin and vancomycin, but 81% and 43% of the penicillin G-resistant strains were intermediately resistant to cefotaxime and imipenem, respectively. Strains belonged to 16 different capsular types: 73% belonged to types 19F and 23F, and 97% of strains belonging to these two types exhibited either intermediate or complete resistance to penicillin G.

Adolescent↗
PubMed1995

Colorimetric microwell plate hybridization assay for detection of amplified Mycobacterium tuberculosis DNA from sputum samples.

We developed a colorimetric microwell plate hybridization assay (CoMPHA) for the specific detection of 5'-biotinylated amplified Mycobacterium tuberculosis DNA. The optical densities of the CoMPHA corresponded to the initial amounts of purified template DNA. Here, we show that the CoMPHA is useful in distinguishing the PCR-positive and PCR-negative samples.

Base Sequence↗
PubMed1994

Antimicrobial susceptibility of Campylobacter fetus subsp. fetus isolated from blood and synovial fluid.

Campylobacter fetus subsp. fetus is a rare human pathogen, but can cause serious extraintestinal infections. Effective antimicrobial agent is required for the therapy, but we have very limited knowledge on the susceptibility of the organism. In this study, the susceptibility of 25 isolates of the organism to 14 antimicrobial agents was tested by an agar dilution method. Antimicrobial agents with low MIC ranges, in micrograms/ml, were: meropenem < or = 0.25, dirithromycin < or = 0.5, gentamicin < or = 1, amikacin, ofloxacin, tetracycline and erythromycin < or = 2. The MIC range of cefepime was 0.5-8 micrograms/ml, but those of other beta-lactams were relatively high. All of the isolates were interpreted to be susceptible to cefepime, meropenem, amikacin, gentamicin, ofloxacin, tetracycline and dirithromycin. A significant proportion of the isolates were either intermediate or resistant to ampicillin, cephalothin, cefotaxime, aztreonam, loracarbef and erythromycin. In conclusion, the organism remains susceptible to aminoglycosides and tetracycline. Greater in vitro activity of meropenem, ofloxacin and dirithromycin require clinical evaluation.

Anti-Bacterial Agents↗
PubMed1993

In-vitro activities of cefepime against Enterobacter cloacae, Serratia marcescens, Pseudomonas aeruginosa and other aerobic gram-negative bacilli.

Infections caused by resistant bacterial pathogens such as Citrobacter freundii, Enterobacter cloacae, Serratia marcescens and Pseudomonas aeruginosa have become an increasing problem with respect to therapy in large medical centres in Korea. The MICs of cefepime for aerobic Gram-negative bacilli isolated during 1991, mostly from in-patients in a hospital in Seoul, were determined by the agar dilution method and compared with those of several other antimicrobials. Of the agents tested, cefepime had the lowest MIC90s for C. freundii and E. cloacae (0.12 and 8 mg/L, respectively). The MIC90s of cefepime and amikacin (both 8 mg/L) were the lowest for S. marcescens. The MIC90s of cefepime, ceftazidime and doxycycline (all 32 mg/L) were the lowest for Acinetobacter anitratus. For P. aeruginosa, the MIC90 was relatively high (32 mg/L) but still the lowest of the antimicrobials tested. Of the cefotaxime-resistant E. cloacae isolates studied, only 7% were resistant to cefepime, while 100%, 96% and 89% were resistant to ceftazidime, ceftizoxime and cefuzonam, respectively. Similarly, only 6% of gentamicin-resistant isolates were resistant to cefepime, compared with 91%, 72%, 69% and 63% to ceftazidime, ceftizoxime, cefuzonam and cefotaxime, respectively. In conclusion, isolates from Korean patients are often resistant to several antimicrobial agents. However, based on the results of this study, cefepime may be very useful as treatment for patients with nosocomial infections caused by aerobic Gram-negative bacilli, including those which are resistant to most of the third-generation cephalosporins and gentamicin.

Aminoglycosides↗
PubMed1993

[Identification of enterotoxin-producing Clostridium perfringens by the polymerase chain reaction].

Polymerase chain reaction was applied to identify enterotoxin-producing Clostridium perfringens by amplifying a segment of the C. perfringens enterotoxin gene. All of the four enterotoxin-positive reference strains tested were PCR positive while an enterotoxin-negative strain was PCR positive. All 17 clostridial strains (16 species) other than C. perfringens were PCR negative. With clinical strains isolated from various clinical specimens in Japan, Korea, and Thailand, all three enterotoxin-positive isolates were PCR positive and all 82 enterotoxin-negative isolates were PCR negative. PCR results for amplifying a region containing the initiation codon of the C. perfringens enterotoxin gene also demonstrated complete agreement with enterotoxin producibility. These results suggested that the PCR assay is a rapid and simple test for identifying the enterotoxin-producing C. perfringens without using any cultures and spore treatments.

Base Sequence↗
PubMed1993

Trend of isolation and serotypes of group B streptococci in Korea.

Group B streptococci (GBS) neonatal infection, a prevalent disease in western countries, is considered rare in Korea. GBS neonatal infection is known to be often due to serotype III organisms, but the serotypes in Korea have not been reported. In this study, GBS were frequently isolated from specimens of genitalia, urine and various pus. Among the 186 isolates 14 (7.5%) were from neonates, two with concomitant bacteremia and meningitis and one with pneumonia. Frequently isolated GBS serotypes were Ib (9.2%), Ib/c (26.6%) and III/R (23.9%). Change of frequently isolated serotypes during the study was noted, but JM9 which became increasingly isolated in Japan was not found. It is concluded that less prevalence of severe neonatal GBS infection in Korea is not due to the absence of serotype III, but possibly due to low genital carriage rate of GBS by pregnant women.

Female↗
PubMed1993

Scrub typhus in Korea: importance of early clinical diagnosis in this newly recognized endemic area.

Scrub typhus became a well recognized infectious disease threat to military operations in the Pacific Theater during World War II. Early diagnosis and treatment with tetracycline or chloramphenicol dramatically reduces the mortality and morbidity of this disease. Korea is a newly recognized scrub typhus endemic country. We report our experience with 189 scrub typhus patients seen at a civilian outpatient clinic in Chinhae, Republic of Korea, from 1985 through 1990, and verify the accuracy of clinical diagnosis by serologic tests.

Adolescent↗