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Y H Chen

Publications and source records attributed to Y H Chen.

At least 55 records · Page 3Linked to original sources
PubMed2001

Histone deacetylase inhibitors increase p21(WAF1) and induce apoptosis of human myeloma cell lines independent of decreased IL-6 receptor expression.

Histone deacetylase (HDAC) inhibitors cause growth arrest and apoptosis of cancer cells by both p21-dependent and independent mechanisms. Decreased expression of growth factor receptors may be a key factor in the p21-independent mechanism, although this has not been directly tested. We have tested the effects of sodium butyrate and trichostatin A on human myeloma cell lines and have observed G1 arrest and apoptosis associated with increased expression of p21(WAF1), Bax, Rb dephosphorylation, and decreased IL-6 receptor (IL-6R) expression. Experiments to determine the role of disruption of IL-6 signaling as a result of decreased IL-6 receptor expression in mediating these effects were conducted using a stable transfectant of the OPM-2 line which constitutively expressed the IL-6 receptor. Our results indicated that decreased IL-6R expression was not required for induction of p21(WAF1) or apoptosis. Thus, HDAC inhibitors appear to activate multiple cellular pathways, leading to growth arrest and apoptosis, and their use in the treatment of myeloma, particularly in combination with other agents, warrants further investigation.

Apoptosis↗
PubMed2001

Salvianolic acid B attenuates VCAM-1 and ICAM-1 expression in TNF-alpha-treated human aortic endothelial cells.

Attachment to, and migration of leukocytes into the vessel wall is an early event in atherogenesis. Expression of cell adhesion molecules by the arterial endothelium may play a major role in atherosclerosis. It has been suggested that antioxidants inhibit the expression of adhesion molecules and may thus attenuate the processes leading to atherosclerosis. In the present study, the effects of a potent water-soluble antioxidant, salvianolic acid B (Sal B), and an aqueous ethanolic extract (SME), both derived from a Chinese herb, Salvia miltiorrhiza, on the expression of endothelial-leukocyte adhesion molecules by tumor necrosis factor-alpha (TNF-alpha)-treated human aortic endothelial cells (HAECs) were investigated. When pretreated with SME (50 and 100 microg/ml), the TNF-alpha-induced expression of vascular adhesion molecule-1 (VCAM-1) was notably attenuated (77.2 +/- 3.2% and 80.0 +/- 2.2%, respectively); and with Sal B (1, 2.5, 5, 10, and 20 microg/ml), 84.5 +/- 1.9%, 78.8 +/- 1.2%, 58.9 +/- 0.4%, 58.7 +/- 0.9%, and 57.4 +/- 0.3%, respectively. Dose-dependent lowering of expression of intercellular cell adhesion molecule-1 (ICAM-1) was also seen with SME or Sal B. In contrast, the expression of endothelial cell selectin (E-selectin) was not affected. SME (50 microg/ml) or Sal B (5 microg/ml) significantly reduced the binding of the human monocytic cell line, U937, to TNF-alpha-stimulated HAECs (45.7 +/- 2.5% and 55.8 +/- 1.2%, respectively). SME or Sal B significantly inhibited TNF-alpha-induced activation of nuclear factor kappa B (NF-kappaB) in HAECs (0.36- and 0.48-fold, respectively). These results demonstrate that SME and Sal B have anti-inflammatory properties and may explain their anti-atherosclerotic properties. This new mechanism of action of Sal B and SME, in addition to their previously reported inhibition of LDL, may help explain their efficacy in the treatment of atherosclerosis.

Antioxidants↗
PubMed2001

Colonic transit disorders in systemic sclerosis.

Systemic sclerosis (SS) alters smooth muscle function throughout the gastrointestinal tract, the oesophagus being the segment most often involved. Involvement of the colon, though less common, may lead to life-threatening complications. We studied 23 unselected patients with SS and 20 age-matched healthy controls using radionuclide colon transit studies. The geometric centre (GC) at 4 and 24 hours was used to summarise overall transit in the colon. In patients with SS, colon transit was delayed (GC4: 0.39 +/- 0.36 vs 0.85 +/- 0.45; P=0.001) (GC24: 1.68 +/- 0.9 vs 2.58 +/- 1.08; P=0.006). These findings suggest that delayed colon transit is common in patients with SS.

Adolescent↗
PubMed2001

A novel genetic island of meningitic Escherichia coli K1 containing the ibeA invasion gene (GimA): functional annotation and carbon-source-regulated invasion of human brain microvascular endothelial cells.

The IbeA (ibe10) gene is an invasion determinant contributing to E. coli K1 invasion of the blood-brain barrier. This gene has been cloned and characterized from the chromosome of an invasive cerebrospinal fluid isolate of E. coli K1, strain RS218 (018:K1: H7). In the present study, a genetic island of meningitic E. coli containing ibeA (GimA) has been identified. A 20.3-kb genomic DNA island unique to E. coli K1 strains has been cloned and sequenced from an RS218 E. coli K1 genomic DNA library. Fourteen new genes have been identified in addition to the ibeA. The DNA sequence analysis indicated that the ibeA gene cluster was localized to the 98 min region and consisted of four operons, ptnIPKC, cglDTEC, gcxKRCI and ibeRAT. The G+C content (46.2%) of unique regions of the island is substantially different from that (50.8%) of the rest of the E. coli chromosome. By computer-assisted analysis of the sequences with DNA and protein databases (GenBank and PROSITE databases), the functions of the gene products could be anticipated, and were assigned to the functional categories of proteins relating to carbon source metabolism and substrate transportation. Glucose was shown to enhance E. coli penetration of human brain microvascular endothelial cells and exogenous cAMP was able to block the stimulating effect of glucose, suggesting that catabolic regulation may play a role in control of E. coli K1 invasion gene expression. Our data suggest that this genetic island may contribute to E. coli invasion of the blood-brain barrier through a carbon-source-regulated process.

Amino Acid Sequence↗
PubMed2001

Characterization of interaction between C-domain on HIV-1 gp41 and the putative receptor protein p62.

Based on the fact that the binding of HIV-1 gp41 to the putative cellular receptor protein p62 could be inhibited by the C-domain peptide of gp41, we wanted to confirm the interaction of the C-domain with p62 and to characterize the receptor-binding site on the C-domain. We attempted to isolate the putative receptor protein p62 from cell lysates of the human B cell line Raji by affinity chromatography using sepharose-columns which were conjugated with three different peptides of the C-domain respectively. A protein of 62 kDa was isolated by peptide (NP2)-sepharose-column, while none of the proteins was identified in eluates of the other two overlapped peptides of C-domain, indicating that HIV-1 gp41 by the region aa635-664 of C-domain binds to the putative receptor protein p62. Besides, CD spectroscopy analysis revealed that only a NP2 peptide could induce significant conformational change of P62. In addition, the interaction between P62 and three peptides of the C-domain was characterized by the surface plasma resonance (SPR) measurement. It was indicated that only the NP2 peptide significantly inhibited the interaction between rsgp41 and the putative receptor P62, confirming that the protein p62 may serve as a potential receptor for gp41 binding, and the peptide NP2 contains an integrate binding site for gp41 binding to p62.

Amino Acid Sequence↗
PubMed2001

Folate deficiency-induced oxidative stress and apoptosis are mediated via homocysteine-dependent overproduction of hydrogen peroxide and enhanced activation of NF-kappaB in human Hep G2 cells.

Folate coenzymes are critical for de novo synthesis of purine and thymidine, and for interconversion of amino acids. Folate deficiency inhibits cellular proliferation, disturbs cell cycling, causes genetic damage and eventually results in cell death. Previously, we demonstrated that the demise of human hepatoma Hep G2 cells mediated by folate deficiency proceeded via a p53-independent apoptosis, and the perturbation of intracellular calcium homeostasis was also shown to be involved. To further delineate the mechanism associated with this observed phenomenon, Hep G2 cells were cultivated in the control or folate-deficient media (control media lacking folate, glycine, thymidine and hypoxanthine) for 4 weeks. At the end of this cultivation period, we found that TBARS (an index of lipid peroxidation) concentrations in the folate-deficient cells were drastically increased as compared to the control cells (0.04 vs 0.01 nmole/10(6) cells), indicating that a severe oxidative stress of the former cells had occurred. This phenomenon was also shown to coincide with the ability of these folate-deficient cells to elaborate increased amounts of H2O2 as compared to its folate-supplemented cells (2.87 vs 0.98 nmole/10(5) cells/h). Furthermore, the accelerated production of H2O2 by the folate-deficient cells was also closely correlated with the elevated homocysteine concentrations released in the culture medium (15.37 +/- 2.4 vs 3.58 +/- 2.4 micromole/L; P< 0.001). Finally, we demonstrated that folate deficiency was indeed capable of activating a redox-sensitive transcription factor, NF-kappaB, which is crucial in the control of a reactive oxygen species-mediated apoptosis. In summary, we show that folate deficiency-induced apoptosis is proceeded via the enhanced activation of NF-kappaB, which is the resulting form of the homocysteine-mediated overproduction of hydrogen peroxide.

Apoptosis↗
PubMed2001

HIV epitope-peptides in aluminum adjuvant induced high levels of epitope-specific antibodies.

Some neutralizing epitopes on HIV-1 envelope proteins were shown to induce antibodies that could effectively inhibit the infection of different HIV-1 strains in vitro. But only very low levels of antibodies to these epitopes were determined in the HIV-1 infected individuals. In this study, the aluminum (alum) adjuvant to increase the immunogenicity of the neutralizing epitopes was used. Three epitope-peptides [C-(ELDKWAG)4, C-(RILAVERYLKD-G)2 and C-(GPGRAFY)2], which contain three epitopes (ELDKWA, RILAVERYLKD, GPGRAFY) from the HIV-1 Env proteins, were synthesized and conjugated to carrier protein keyhole limpet hemocyanin (KLH). The epitope-vaccines C-(ELDKWAG)4-KLH and C-(RILAVERYLKD-G)2-KLH in alum induced high levels of epitope-specific antibodies recognizing the epitopes from epitope-peptides C-(ELDKWAG)4 and C-(RILAVERYLKD-G)2, as well as the gp41 C-domain peptides P2 [C-TSLIHSLIEESQNQQEKNEQELLELDKWA (aa 646-674)] and P1 [LQARILAVERYLKDQQL (aa 583-599)] and the recombinant soluble gp41 (rsgp41) bearing both epitopes (antibody titer in rabbit sera was 1:12800-25,600 dilution). Immunoblotting analysis demonstrated that the antibodies in both antisera bound to rsgp41, indicating that both antibodies recognized the natural epitopes on rsgp41 protein. The epitope-vaccines C-(GPGRAFY)2-KLH induced moderate GPGRAFY epitope-specific antibody response with a titer of 1:6,400. In contrast, as it was demonstrated in previous studies, the immunization with rgp160 induced weak antibody response to these three epitopes (titer of 1:400-1600). This suggests that epitope-peptides conjugated to KLH when infected with alum significantly increases immunogenicity of gp41 neutralizing epitopes providing a hope for the development of an HIV-1 vaccine.

AIDS Vaccines↗
PubMed2001

Depigmented genital extramammary Paget's disease: a possible histogenetic link to Toker's clear cells and clear cell papulosis.

BACKGROUND: The histogenesis of extramammary Paget's disease (EMPD) is still controversial. Benign pagetoid cells of the nipple first described by Toker and the similar clear cells found in white maculopapules of clear cell papulosis (CCP) have been proposed to be potential precursor cells giving rise to EMPD and primary intraepidermal Paget's disease in the nipple. The observation of a rare case of depigmented EMPD provided us with a chance to examine further the interesting Toker's clear cell/CCP hypothesis. METHODS: We performed pathologic studies, including Fontana-Masson stain and immunostaining for AE1/AE3 and S100P, on a new case of depigmented EMPD manifesting a 4 x 3 cm hypopigmented-depigmented patch on the root of the penis. RESULTS: The lesion showed extensive intraepithelial proliferation of atypical pagetoid cells with markedly reduced epidermal melaninization but nearly normal numbers of melanocytes. The tumor cells were strongly positive for AE1/AE3 by immunostaining. Some tumor cells displayed tadpole-like morphology resembling the pagetoid cells of CCP. Such morphology was not observed in two random examples of non-depigmented genital EMPD. CONCLUSIONS: The findings of tadpole-shaped pagetoid cells and depigmentation in the present case suggest that depigmented EMPD may be histogenetically related to CCP. Depigmented EMPD should be considered in the differential diagnosis of vitiligo, depigmented mycosis fungoides and lichen sclerosus located along the milk line.

Aged↗
PubMed2001

Fludarabine and melphalan-based conditioning for patients with advanced hematological malignancies relapsing after a previous hematopoietic stem cell transplant.

Severe regimen-related toxicity often complicates second transplant procedures performed in patients with hematological malignancies that have relapsed after an initial hematopoietic stem cell (HSC) transplant. Therefore, we studied the safety and efficacy of a reduced-intensity fludarabine and melphalan based conditioning regimen in 11 patients who had relapsed following an autologous (n = 7) or allogeneic (n = 4) HSC transplant. All patients received allogeneic peripheral blood HSC from either an HLA-identical (n = 7) or an HLA-mismatched (n = 4) relative. Diagnoses included AML (n = 9), ALL (n = 1), or Hodgkin's disease (n = 1). Only one patient was in complete remission at the time of second transplant. The median interval between first transplant and relapse was 163 days (range 58-1885). Recipients of HLA-mismatched transplants received antithymocyte globulin in addition to fludarabine and melphalan as part of the conditioning regimen. All 11 patients received acute GVHD prophylaxis consisting of tacrolimus and methotrexate. Ten of 11 patients achieved hematopoietic engraftment with a median time to absolute neutrophil count >0.5 x 10(9)/l and to platelet count of >20 x 10(9)/l of 14 and 19 days, respectively. All engrafting patients achieved 100% donor chimerism on initial analysis, except for one with persistent leukemia at day +19. Two patients experienced grade 3 regimen-related toxicity, manifesting as acute renal failure. Acute GVHD grades 2-4 occurred in two recipients and chronic GVHD in four. The 100-day mortality from all causes was 36%. Ten of 11 patients (91%) died a median of 140 days (range 9-996) after the second transplant. The causes of death included relapse (n = 5), sepsis (n = 4), and idiopathic pneumonia syndrome (n = 1). One patient with AML survives in remission at 880 days post-transplant. We conclude that fludarabine- and melphalan-based conditioning promotes full donor chimerism, even following HLA-mismatched transplants. However, the regimen may be more beneficial when applied to patients undergoing allogeneic HSC transplantation earlier in their disease course.

Adult↗
PubMed2001

Altered expression of nuclear matrix proteins in etoposide induced apoptosis in HL-60 cells.

The events of cell death and the expression of nuclear matrix protein (NMP) have been investigated in a promyelocytic leukemic cell line HL-60 induced with etoposide. By means of TUNEL assay, the nuclei displayed a characteristic morphology change, and the amount of apoptotic cells increased early and reached maximun about 39% after treatment with etoposide for 2 h. Nucleosomal DNA fragmentation was observed after treatment for 4 h. The morphological change of HL-60 cells, thus, occurred earlier than the appearance of DNA ladder. Total nuclear matrix proteins were analyzed by 2-dimensional gel electrophoresis. Differential expression of 59 nuclear matrix proteins was found in 4 h etoposide treated cells. Western blotting was then performed on three nuclear matrix acssociated proteins, PML, HSC70 and NuMA. The expression of the suppressor PML protein and heat shock protein HSC70 were significantly upregulated after etoposide treatment, while NuMA, a nuclear mitotic apparatus protein, was down regulated. These results demonstrate that significant biochemical alterations in nuclear matrix proteins take place during the apoptotic process.

Antigens, Nuclear↗
PubMed2001

Lack of evidence to support the association of the human prion gene with schizophrenia.

Recently a new variant of Creutzfeldt-Jakob disease, a human prion disease, with prominent psychiatric manifestations in the early stage was identified, suggesting that human prion disease may be associated with mental disorders. Furthermore, a novel missense mutation with asparagine-to-serine substitution at codon 171 of the human prion gene (N171S) was identified in a family with severe psychiatric symptoms. This finding provides further clue that the prion gene may be a susceptibility gene for certain psychiatric disorders. We systematically sequenced the protein-coding and untranslated exons of prion gene in 62 Han Chinese schizophrenic patients with positive family history from Taiwan. We identified two polymorphisms that alter amino acid sequences, a methionine/valine at codon 129 (M129V) and a glutamate/lysine at codon 219 (E219K), respectively. Further comparison of the genotype, allele and haplotype frequency distributions of these two polymorphisms between 234 schizophrenic patients and 100 non-psychotic controls, however, did not reveal significant differences between two groups. Besides, no other mutations in the prion gene were identified in these 62 patients. Hence, our results suggest that the prion gene may not play a major role in conferring susceptibility to schizophrenia.

Creutzfeldt-Jakob Syndrome↗
PubMed2001

Development of a capillary electrophoresis-77 K luminescence detection system for online spectral identification.

We have demonstrated that capillary electrophoresis (CE) can be easily interfaced with 77 K luminescence spectroscopy (LS) for separation and online spectral identification of structurally similar analytes. This novel CE-LS apparatus consists of a regular CE system, instrumentation for LS and a specially designed capillary Dewar. When the separating molecules traverse into the cryostat detection window, liquid nitrogen is added, freezing the separating analyte zones within the capillary. At low temperature, detection limits are improved via signal averaging and the inherent increase in quantum yield at 77 K. We present the first application of the CE-LS system to structural isomers (2,3- and 3,4-methylenedioxymethamphetamine) and stereoisomers (trans- and cis-resveratrol). With this approach, the CE-LS interfacing provides a sensitive, accurate, rapid, simple and economic methodology for analytical chemistry.

Journal Article↗
PubMed2001

Effect of occlusal trauma on healing of periapical pathoses: report of two cases.

AIM: To present two clinical cases and demonstrate that occlusal trauma may affect healing of periapical pathoses. SUMMARY: Two teeth with periradicular disease did not respond successfully to conventional root canal treatment or endodontic surgery. Occlusal adjustment was finally performed on both cases. After occlusal adjustment, uncomplicated healing and periapical repair occurred in both cases. The findings in these two cases suggest that occlusal trauma may play a role in the healing of periapical pathoses. KEY LEARNING POINTS: Occlusal trauma is positively correlated with changes in periodontal tissues. Although experiments in animals have shown that application of forces to teeth will not induce further periodontal destruction, we believe that some failures of root canal treatment may be due to the presence of occlusal trauma modulating the responses of inflamed periapical tissues or apical pathoses with persistent infection.

Adult↗
PubMed2001

Effects of flowable composite lining and operator experience on microleakage and internal voids in class II composite restorations.

STATEMENT OF PROBLEM: When inexperienced clinicians perform class II composite restorations, improper placement techniques can lead to problems, including marginal adaptation and void formation. PURPOSE: The aim of this study was to determine the influence of flowable composite linings on marginal microleakage and internal voids in class II composite restorations performed by practitioners with different levels of experience. MATERIAL AND METHODS: Eighty extracted molars were prepared with mesial and distal class II cavity preparations and divided into 4 groups. Each group was restored separately with the following materials: Prodigy/Revolution lining (group I), Prodigy (group II), Tetric Ceram/Tetric Flow lining (group III), and Tetric Ceram (group IV). Each group was equally divided and restored by 2 practitioners, one experienced and another untrained in composite restorations. After restoration, all teeth were stored for 24 hours, thermocycled (at 5 degrees C to 60 degrees C) 1500 times, and soaked in 2% basic Fuchsin dye for 24 hours. After soaking, the teeth were sectioned, and gingival marginal microleakage and internal voids (at the gingival wall interface and in the cervical and the occlusal parts) were recorded. Data were analyzed with the Kruskal-Wallis test. RESULTS: There was no significant reduction in microleakage for either practitioner. There were fewer interface voids within pairs with or without flowable composite linings made by the experienced practitioner (P<.05). CONCLUSION: When flowable composite lining was placed at the gingival floor of a class II composite restoration by an experienced practitioner, voids in the restored interface were reduced. Gingival marginal sealing was not improved by the same technique.

Composite Resins↗
PubMed2001

Antigenicity and predefined specificities of the multi-epitope vaccine in candidate consisting of neutralizing epitope and mutated epitopes suggested a new way against HIV-1 mutation.

A seven-amino acid epitope GPGRAFY located inside the V3 loop on envelope protein gp120 of HIV-1 is the principal neutralizing epitope (PNE), and a subset of anti-V3 antibodies specific for this epitope show a broad range of neutralizing activity. But this epitope undergoes restricted mutation. In this study, three epitope peptides [C-(GPGRAFY)2, C-(GPGQTFY)2 and C-(GPGQAWY)2] that contain neutralizing epitope GPGRAFY and its two mutated epitope GPGQTFY and GPGQAWY, were synthesized and then conjugated to carrier protein KLH (keyhole limpet hemocyanin). the epitope-vaccines C-(GPGRAFY)2-KLH, C-(GPGQTFY)2-KLH and C-(GPGQAWY)2-KLH induced high levels of antibodies to three V3 loop peptides that contain these epitopes respectively, and the antibody response induced by each epitope-vaccine showed predefined epitope-specific. When these three epitope-peptides mixed together and conjugated to carrier protein, or conjugated to carrier protein separately and then mixed together, high levels of epitope-specific antibodies which respectively recognized these epitopes on V3 loop peptide and both mutated peptides all can be induced by both of them. In blotting assay, these epitope-specific antibodies all recognized the neutralizing epitope and mutated epitopes on peptides respectively. In addition, the reactivity of the antibodies with whole gp120 molecule which contained the epitope GPGRAFY was tested. Only the GPGRAFY-epitope-specific antibodies but not the other antibodies recognized the gp120 molecule. These results provide experimental evidence that the candidate multi-epitope-vaccine containing neutralizing epitope and mutated epitopes may bring new hope against viral mutation resulting in HIV-1 immune evasion and may be developed as an effective vaccine with a broad neutralizing activity against HIV-1 infection.

AIDS Vaccines↗
PubMed2001

Immunogenicity and specificity of the candidate multi-epitope-vaccines against HIV-1.

The failure of some candidate HIV-1 vaccines may result from inducing very weak neutralization activity against representative primary viral isolates. Based on our hypothesis that epitope-vaccine may be a new strategy to induce high levels of neutralizing antibodies against HIV-1, we designed two candidate multi-epitope-vaccines, EP1 [C-G-(ELDKWA-GPGRAFY)2-K] and EP2 (CG-GPGRAFY-G-ELDKWA-G-RILAVERYLKD), containing three neutralizing epitopes (GPGRAFY, ELDKWA and RILAVERYLKD) on HIV-1 envelope protein, and expected them to induce epitope-specific antibodies of predefined epitope-specificity. The two peptides were conjugated to carrier protein bovine serum albumin (BSA) and used for immunization of rabbits. Proteins were purified from the rabbit sera induced by both candidate multi-epitope-vaccines (EP1-BSA and EP2-BSA) through affinity chromatography with epitope-peptide-conjugated sepharose-column, and identified as antibodies in silver-staining and immunoblotting. These antibodies were demonstrated to recognize three neutralizing epitopes on peptides and the recombinant gp41 in ELISA-assay and immunoblotting. These results indicated that both candidate multi-epitope-vaccines could induce high levels of antibodies of predefined epitope-specificity which recognized a few of neutralizing epitopes on peptides and protein, providing experimental evidence for the new strategy to develop an effective neutralizing-antibody-based multi-epitope-vaccine against HIV-1.

AIDS Vaccines↗
PubMed2001

Molecular epidemiology and mutations at gyrA and parC genes of ciprofloxacin-resistant Escherichia coli isolates from a Taiwan medical center.

Sixty-five ciprofloxacin-resistant clinical Escherichia coli isolates were collected from a Taiwan Medical Center from December 1998 to February 1999. All 65 clinical isolates were resistant (MICs > or = 4 microg/mL) to the following fluoroquinolones: ofloxacin, levofloxacin, sparfloxacin, and trovafloxacin. These isolates were cross-resistant to chloramphenicol (65 isolates, 100%), tetracycline (65 isolates, 100%), cefuroxime (64 isolates, 98.5%), ampicillin (57 isolates, 87.7%), gentamicin (53 isolates, 81.5%), and cephalothin (24 isolates, 36.9%). Pulsed-field gel electrophoresis (PFGE) revealed a high diversity among the genomes of these isolates and indicated that clonal spread was not responsible for the prevalence of ciprofloxacin resistance in the hospital. Sequencing of the polymerase chain reaction (PCR) amplified products of the quinolone resistance determining regions (QRDRs) of gyrA and parC showed that all isolates carrying double mutations in gyrA at codon 83 and 87 and at least one parC mutation at codon 80 and/or 84. The mutation at codon 83 of GyrA from serine to leucine (S83L) was present in all the clinical isolates. The most prevalent pattern was the S83L mutation and the mutation at codon 87 from an aspartate to an asparagine (D87N) of GyrA plus a mutation from a serine to an isoleucine (S80I) at codon 80 of ParC (63.2%). This indicated that the presence of high-level resistance to quinolones in clinical E. coli isolates were associated with mutations at hot spots, codon 83 and 87 in GyrA and followed by subsequent mutation in either codon 80 and/or 84 in ParC.

Anti-Infective Agents↗