Use of topical colistin in bacterial keratitis caused by extensively drug-resistant Pseudomonas Aeruginosa: a case report / Uso de colistina tópica em ceratite bacteriana causada por Pseudomonas Aeruginosa extensivamente resistente a medicamentos: relato de caso

ABSTRACT Bacterial keratitis caused by multidrug-resistant strains of Pseudomonas aeruginosa is a therapeutic challenge due to a limited number of active antimicrobials and rapid progression to corneal necrosis and perforation. To report the use of topical colistin and surgical tarsorrhaphy in a case of keratitis caused by extensively drug-resistant Pseudomonas aeruginosa in a patient with severe coronavirus disease-2019 (COVID-19) pneumonia. A 56-year-old male was admitted to the intensive care unit with clinical symptoms of severe COVID-19 pneumonia. During his stay in the unit, he developed rapidly progressive keratitis with Pseudomonas aeruginosa resistant to all drugs except for colistin on culture. Due to incomplete lid closure, a temporary tarsorrhaphy was performed, and a regimen of descending-dose topical colistin was initiated. After five weeks, keratitis resolved completely. Extensively drug-resistant Pseudomonas aeruginosa is an unusual cause of bacterial keratitis. We describe the safe and effective use of topical colistin in a case with severe corneal involvement.

RESUMO A ceratite bacteriana causada por cepas multirresistentes de Pseudomonas aeruginosa é um desafio terapêutico, devido à disponibilidade limitada de antimicrobianos e à rápida progressão para necrose e perfuração da córnea. O objetivo deste artigo é relatar o uso de colistina tópica e tarsorrafia cirúrgica em um caso de ceratite por Pseudomonas aeruginosa amplamente resistente a medicamentos em um paciente com pneumonia grave por COVID19. Um homem de 56 anos foi internado em uma unidade de terapia intensiva com sintomas clínicos de pneumonia grave por COVID19. Durante sua permanência na unidade de terapia intensiva, o paciente desenvolveu uma ceratite rapidamente progressiva, cuja cultura foi positiva para Pseudomonas aeruginosa resistente a todos os antimicrobianos, exceto colistina. Devido ao fechamento incompleto da pálpebra, foi realizada uma tarsorrafia temporária e foi instituído um esquema de colistina tópica em doses decrescentes. Após cinco semanas, a resolução completa da ceratite foi alcançada. Pseudomonas aeruginosa amplamente resistente a medicamentos é uma causa incomum de ceratite bacteriana. Este relato descreve o uso seguro e eficaz da colistina tópica em um caso com comprometimento corneano grave.

Effects of adriamycin resistance cell-derived exosomes on the proliferation and migration of osteosarcoma cells through drug resistance transmission / 中华骨科杂志

Objective:To explore the relationship and underlying mechanism between exosomes derived from doxorubicin-resistant osteosarcoma cells and MDR1 and miRNAs. Methods:MG63 and U2OS cell lines were selected to construct doxorubicin-resistant strains, and the 50% inhibitory concentration (half maximal inhibitory concentration, IC 50) of drug-resistant and sensitive strains was detected by MTT, and fluorescence staining was performed at intervals of 15 min between 15 and 120 min to detect the change of fluorescence intensity. RT-PCR and Western Blot were used to detect the expression levels of MDR1 P-gp to verify the drug resistance of osteosarcoma cells. Exosomes were identified by particle size analysis and Western Bolt detection. The endocytosis of PKH26-labeled exosomes from doxorubicin-resistant cells was observed, and the proliferation level and migration of exosomes from doxorubicin-resistant cells co-cultured with osteosarcoma cells were detected by MTT assay and cell scratch assay. The differential expression levels of miRNAs in osteosarcoma-sensitive and drug-resistant cells were verified by sequencing and bioinformatics analysis and RT-PCR assay. Tumor growth, serum exosome identification and mRNA expression level of miR-21-5p in tumor-bearing nude mice between normal osteosarcoma cell group and drug-resistant group, drug-resistant+normal exosome group, drug-resistant+drug-resistant+drug-resistant exosome group were observed. MDR1 expression level in tumor tissue was detected by RT-PCR, Western Blot and immunohistochemistry. Results:The IC 50 of two adriamycin resistant strains were 2.21 vs. 11.81 μg/ml and 0.93 vs. 11.81 μg/ml, respectively, and the fluorescence intensity decreased faster than that of normal strains. The relative mRNA expression levels of MDR1 in two cell lines were normal 1.12±0.16, 1.02±0.11 and drug-resistant 2.15±0.10, 2.127±0.12, respectively. The relative protein expression of P-gp was normal 0.92±0.11, 0.73±0.10 and drug-resistant 0.46±0.03, 0.30±0.04, the differences were statistically significant ( P<0.05). Drug-resistant exosomes can enter osteosarcoma cells through endocytosis and concentrate in the cytoplasm when co-cultured with normal strains. Osteosarcoma cells were co-cultured with drug-resistant exosomes at 2, 4, 6, and 8 μg/ml adriamycin, respectively. Compared with normal group, the proliferation level in drug-resistant group was significantly increased. Compared with the normal cell group 35.95±3.92, 6.72±3.55 and the normal exosome group 51.22±5.55, 19.31±1.93, the drug-resistant cell group 54.20±9.32, 19.24±2.88 and drug-resistant exosome group 76.40±5.41, 30.26±4.87, all had significantly higher cell mobility, the difference was statistically significant ( P<0.05). Exosome sequencing and biogenic analysis of 10 highly upregated miRNAs to validate mRNA expression differences between normal and drug-resistant strains by RT-PCR, showing a significant increase in miR-21-5p expression level of drug-resistant strains (5.89±0.26 vs. 0.99±0.06; 1.05±0.07 vs. 8.80±0.93, P<0.05), the difference was statistically significant ( P<0.05). In MG63 and U2OS, the normal cell group and drug-resistant cell group, and the normal exosome group and drug-resistant exosome group were compared, the tumor volume and the terminal tumor weight of nude mice were increased to varying degrees. MRNA relative expression levels of miR-21-5p in serum exosomes of nude mice after drug intervention were 0.86±0.07 and 0.86±0.05 in normal cell group, respectively. The values were 1.13±0.12, 1.14±0.12 in drug-resistant cell group, 0.71±0.05, 0.75±0.03 in normal exosome group, and 0.90±0.07, 0.93±0.04 in drug-resistant exosome group. Compared with normal and drug-resistant strains, the expression levels of normal and drug-resistant exosome groups were increased, with statistical significance ( P<0.05). Conclusion:The exosomes of drug-resistant cells in osteosarcoma could enhance the proliferation level and migration ability of cells through intercellular transfer of MDR1 and miRNAs. The expression of MDR1 and miR-21-5p in drug-resistant cells and tumor-forming nude mouse serum and tumor tissues were up-regulated which suggested that it might be involved in regulating the drug resistance process of osteosarcoma.

Colistin resistance in Escherichia coli and Klebsiella pneumoniae in humans and backyard animals in Ecuador / Resistencia a la colistina de las bacterias Escherichia coli y Klebsiella pneumoniae en humanos y animales de granja en Ecuador / Resistência à colistina em Escherichia coli e Klebsiella pneumoniae em humanos e animais de quintal no Equador

ABSTRACT Objective. Colistin is an antibiotic of last resort for treating serious Gram-negative bacterial infections. However, the misuse of colistin, especially as an animal growth promoter, has contributed to increasing antimicrobial resistance, mediated mainly through plasmid transfer of the mcr-1 gene. This study assessed the prevalence of phenotypic and molecular colistin resistance in Escherichia coli and Klebsiella pneumoniae in Ecuador in healthy humans and their chickens and pigs. Methods. Fecal samples were collected from humans and their chickens and pigs in two rural coastal and Amazon regions between April and August 2020. Gram-negative bacteria were isolated and identified using conventional techniques. Phenotypic resistance was determined using the broth microdilution technique, and the mcr-1 gene was detected using conventional polymerase chain reaction. Results. A total of 438 fecal samples were obtained from 137 humans, 147 pigs and 154 chickens. The prevalence of E. coli isolates was 86.3% (378/438) and K. pneumoniae, 37.4% (164/438). Overall, the mcr-1 gene was found in 90% (340/378) of E. coli isolates, with higher prevalences found in isolates from coastal regions (96.5%, 191/198), humans (95.6%, 111/116) and chickens (91.8%, 123/134); for K. pneumoniae, the gene was found in 19.5% (32/164) of isolates, with equal distribution between regions and hosts. Only four isolates, two E. coli and two K. pneumoniae, showed phenotypic resistance: mcr-1 was present in both E. coli strains but absent in the K. pneumoniae strains. Conclusions. Despite a low prevalence of phenotypic resistance to colistin, the high prevalence of the mcr-1 gene in E. coli is of concern. Ecuador's ban on using colistin in animal husbandry must be enforced, and continual monitoring of the situation should be implemented.

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RESUMO Objetivo. A colistina é um antibiótico de último recurso para o tratamento de infecções graves por bactérias Gram-negativas. Entretanto, o uso indevido da colistina, principalmente como promotor de crescimento animal, tem contribuído para o aumento da resistência a antimicrobianos, principalmente por transferência horizontal do gene mcr-1 mediada por plasmídeos. Este estudo avaliou a prevalência de resistência fenotípica e molecular à colistina em Escherichia coli e Klebsiella pneumoniae no Equador em humanos hígidos e em galinhas e porcos por eles criados. Métodos. Entre abril e agosto de 2020, foram coletadas amostras de fezes de habitantes de duas regiões litorâneas e amazônicas do Equador e de galinhas e porcos por eles criados. Bactérias Gram-negativas foram isoladas e identificadas por meio de técnicas convencionais. A resistência fenotípica foi determinada pela técnica de microdiluição em caldo, e o gene mcr-1 foi detectado por reação em cadeia da polimerase convencional. Resultados. Foram obtidas 438 amostras fecais de 137 humanos, 147 suínos e 154 galinhas. A prevalência de isolados de E. coli foi de 86,3% (378/438), e de K. pneumoniae, 37,4% (164/438). Em geral, o gene mcr-1 foi encontrado em 90% (340/378) dos isolados de E. coli, com maiores prevalências encontradas em isolados de regiões litorâneas (96,5%, 191/198), humanos (95,6%, 111/116) e galinhas (91,8%, 123/134); para K. pneumoniae, o gene foi encontrado em 19,5% (32/164) dos isolados, com igual distribuição entre regiões e hospedeiros. Somente quatro isolados, dois de E. coli e dois de K. pneumoniae, demonstraram resistência fenotípica: o gene mcr-1 estava presente em ambas as cepas de E. coli, mas ausente nas de K. pneumoniae. Conclusões. Apesar da baixa prevalência de resistência fenotípica à colistina, a alta prevalência do gene mcr-1 em E. coli é preocupante. É preciso fiscalizar a proibição ao uso agropecuário de colistina no Equador e implementar o monitoramento contínuo da situação.

mcr-1-carrying Enterobacteriaceae isolated from companion animals in Brazil / Enterobacteriaceae portadora de mcr-1 em isolados clínicos de animais de companhia: primeiro relato no Brasil

Plasmid-mediated polymyxin resistance was first described in 2015, in China, in Escherichia coli carrying the mcr-1 (Mobile Colistin Resistance-1) gene. Since then, it has become a major public health challenge worldwide, representing a major threat to human and animal health. In addition, there are still few reports on the prevalence of mcr-1 in Enterobacteriaceae isolated from humans, animals and food. Therefore, the purpose of the study was to investigate the occurrence of the mcr-1 gene in bacterial isolates with phenotypic resistance to polymyxin B obtained from clinical specimens of companion animals. Phenotypic resistance to polymyxin B were determined by broth microdilution and the susceptibility profile to other antimicrobials (amikacin, amoxicillin/clavulanate, ampicillin, ampicillin/sulbactam, aztreonam, cefazolin, cefepime, cefotaxime, cefoxitin, ceftazidime, ceftriaxone, chloramphenicol, ciprofloxacin, doxycycline, ertapenem, gentamicin, imipenem, marbofloxacin, meropenem, phosphomycin, piperacillin/tazobactam, tetracycline, ticarcillin/clavulanate, tobramycin and trimethoprim/sulfamethoxazole) by disc-diffusion agar method. The extraction of bacterial DNA was performed via heat shock followed by spectrophotometric evaluation. To verify the presence of mcr-1, the Polymerase Chain Reaction was employed using specific primers, followed by agarose gel electrophoresis. The positive isolates had the corresponding amplicons sequenced. In this study, there were identified the first isolates of Escherichia coli, Klebsiella spp. and Enterobacter spp. carrying the mcr-1 gene derived from specimens of companion animals in Brazil. Our results suggest the dissemination of resistance to polymyxins in the community and the environment, highlighting the need for surveillance and optimized treatment guidelines.(AU)

A resistência à polimixina mediada por plasmídeo teve sua primeira descrição em 2015, na China, em Escherichia coli portadora do gene mcr-1 (Mobile Colistin Resistance-1) e a partir de então tornou-se um grande desafio para a saúde pública em todo o mundo, constituindo uma grande ameaça à saúde humana e animal. Além disso, ainda existem poucos relatos sobre a prevalência de mcr-1 em Enterobacteriaceae isoladas de humanos, animais e alimentos. Sendo assim, o objetivo do estudo foi investigar a ocorrência do gene mcr-1 em isolados bacterianos com resistência fenotípica à polimixina B, oriundos de materiais clínicos de animais de companhia. A resistência fenotípica à polimixina B foi determinada por microdiluição em caldo e o perfil de sensibilidade aos demais antimicrobianos (amicacina, amoxicilina/clavulanato, ampicilina, ampicilina/sulbactam, aztreonam, cefazolina, cefepime, cefotaxima, cefoxitina, ceftazidima, ceftriaxona, cloranfenicol, ciprofloxacina, doxiciclina, ertapenem, gentamicina, imipinem, marbofloxacino, meropenem, fosfomicina, piperacilina/tazobactam, tetraciclina, ticarcilina/clavulanato, tobramicina sulfametoxazol/trimetoprim) foram determinados pelo método disco difusão. A extração do DNA bacteriano foi realizada via choque térmico, seguido de avaliação espectrofotométrica. Para a verificação da presença do mcr-1 foi utilizada a Reação em Cadeia da Polimerase com emprego de iniciadores específicos, seguida de eletroforese em gel de agarose. Os isolados positivos tiveram os correspondentes amplicons sequenciados. Nesse estudo foram identificados os primeiros isolados de Escherichia coli, Klebsiella spp. e Enterobacter spp. portadores do gene mcr-1 derivados de espécimes de animais de companhia no Brasil. Este estudo sugere a disseminação da resistência às polimixinas na comunidade e no meio ambiente, destacando a necessidade de vigilância e diretrizes otimizadas de tratamento.(AU)

Epidemiologia global de pacientes com tuberculose multidrogarresistente (MDR-TB) e extensivamente resistente (XDR-TB) / Global epidemiology of patients with multidrugresistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB)

A tuberculose multidrogarresistente (MDR-TB) e a tuberculose extensivamente resistente (XDR-TB), levantam preocupações pelo grande número de casos, especialmente na África, Ásia e Europa, e pela taxa de sucesso ainda baixa no tratamento, atingindo 54% para MDR-TB e 30% para XDR-TB. O objetivo do presente estudo é relatar as diferentes realidades epidemiológicas dos doentes com MDR-TB e XDR-TB em diferentes partes do mundo. Foram revisados artigos da última década nas bases científicas disponíveis. Os estudos mostraram que a maioria das pessoas afetadas pela MDR-TB são do sexo masculino, migrantes ou imigrantes, que já haviam sido tratados anteriormente. Descrevemos que o tratamento da tuberculose (TB) usualmente resulta em cura, mas também pode levar à seleção dos bacilos mais resistentes. Mostramos que o surgimento de cepas resistentes na TB se deve ao tratamento inadequado de formas mais simples de TB, com cepas resultantes de manejo difícil e que as populações vulneráveis são as mais afetadas. Salientamos que o abandono do tratamento é fator que comumente origina esse problema complexo da doença e elencamos os genes de resistência mais estudados. (AU)

Multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) raise concerns for their great number of cases, especially in Africa, Asia and Europe, and for their still low treatment success rate, reaching 54% for MDR-TB and 30% for XDR-TB. The objective of this study is to report the epidemiological situation of patients with MDR-TB and XDR-TB in different parts of the world. Articles published in the last decade were collected from available scientific databases and reviewed. The studies showed that most of those affected by MDR-TB are male, migrants or immigrants, and had been previously treated for tuberculosis (TB). We report that TB treatment usually ends in cure, but may also lead to selection of the most resistant bacilli. We show that the emergence of resistant strains in TB is due to inappropriate treatment of simpler forms of TB, resulting in strains of difficult management, and that the most vulnerable populations are the most affected. We emphasize that treatment dropout is the factor most commonly associated with this complicated issue, and also list the most studied multidrug resistance genes. (AU)

Metalo-ß-lactamasas en aislamientos clínicos de pseudomonas aeruginosa en Lima, Perú / Metalo-ß-lactamases in clinical isolates of pseudomonas aeruginosa in Lima, Peru

Con el objetivo de detectar y caracterizar molecularmente las metalo-ß-lactamasas (MßL) en aislamientos clínicos de Pseudomonas aeruginosa, se realizó un estudio trasversal en seis hospitales de referencia de Lima (Perú) en agosto de 2011. Se evaluó 51 aislamientos de P. aeruginosa, resistentes a ceftazidima y con sensibilidad reducida a carbapenémicos. El ensayo fenotípico se realizó con el método de aproximación de discos con sustratos (ceftazidima, imipenem y meropenem) y con ácido etilendiaminotetraacético (EDTA). La detección de genes MßL se realizó mediante la técnica de reacción en cadena de polimerasa multiplex. A través del método fenotípico se detectaron MßL en el 15,7% de los aislamientos, en todos ellos la detección de genes mostró la presencia del gen blaIMP. La descripción del primer reporte de MßL en aislamientos de P. aeruginosa en el Perú debería alertar a los equipos de vigilancia epidemiológica intrahospitalaria para promover su control y prevenir su diseminación.

The aim of this study was to detect and characterize molecularly metallo-ß-lactamase (MßL) in clinical isolates of Pseudomonas aeruginosa. We carry out a cross sectional study in six publics hospital in Lima on August 2011. 51 isolates of P. aeruginosa resistant to ceftazidime and reduced susceptibility to carbapenemes were evaluated.The phenotypic assay was performed using the approximation method with substrate disks (ceftazidime, imipenem and meropenem) and ethylenediaminetetraacetic acid (EDTA). MßL gene detection was performed using the technique of polymerase chain reaction (PCR) multiplex. Through MßL detected phenotypic method in 15.7% of isolates. Detection of genes revealed the presence of the gene in the 8 isolates blaIMP. The first report of MßL in P. aeruginosa in Peru was described, this should alert the monitoring equipment in the institutions to promote control their spread.

Detection of genomic mutations in katG, inhA and rpoB genes of Mycobacterium tuberculosis isolates using polymerase chain reaction and multiplex allele-specific polymerase chain reaction

OBJECTIVE: Isoniazid (INH) and rifampin (RIF) are the most effective first line antibiotics against Mycobacterium tuberculosis. Mutations in several genes determine resistance of M. tuberculosis to INH, with the most common gene target of katG, and resistance to RIF is due to mutation in rpoB gene. The aim of present study was to assess the mutations in the regions related to RIF and INH resistance. METHODS: We characterized 80 clinical isolates of confirmed M. tuberculosis to analyze the most commonly observed INH and RIF mutations. PCR analysis and sequencing were used to detect mutations related to RIF and INH resistance. The multiplex allele-specific-PCR (MAS-PCR) was performed as a comparative assay and for evaluation of this method. RESULTS: The sequencing of the 250-bp region of katG codon 315, revealed point mutations at 5 different codons in 13.7 percent of the M. tuberculosis isolates. The sequencing of the 270-bp central region of the rpoB gene revealed point mutations at 7 different codons in 12 (15 percent) of the M. tuberculosis isolates. The results obtained with MAS-PCR are in accordance with PCR-sequencing with high sensitivity and specificity for katG315, inhA15, and rpoB (531, 516, 526). CONCLUSION: The results of this study suggested that molecular techniques can be used as a rapid tool for the identification of drug resistance in clinical isolates of M. tuberculosis. Both DNA sequencing and MAS-PCR yielded high sensitivity for the detection of RIF and INH mutations and detecting multi-drug resistant tuberculosis cases.

Suppression of MDR1 gene expression and reversal of cisplatin resistance in renal carcinoma cells by RNA interference / 肿瘤

Objective:To investigate the inhibitory effect of RNA interference (RNAi) on the expression of multidrug resistance (MDR1) gene and analyze the altered sensitivities of human renal carcinoma cell line to cisplatin.Methods:Three small interfering RNA (siRNA) sequences targeted MDR1 gene were synthesized and transfected into renal carcinoma A498 cells. The expression level of MDRl mRNA was measured by RT-PCR to identify the most effective siRNA sequence. The recombinant plasmid was packed by lentivirus and transfected into A498 cells. RT-PCR was used to screen the A498 cells with the optimal silencing efficacy. The MDR1 protein expression level in the cloned cells was verified by Western blotting. The inhibitory effect of cisplatin on the proliferation of A498 cells was assessed by MTT assay and the IC_(50) value was calculated. Results:The 3 siRNA sequences suppressed MDR1 gene expression at different degrees. The siRNA 1 sequence silenced MDR1 gene more effectively with a significant reduction of 67%. The MDR1 protein expression greatly decreased in screened A498 cells compared with non-transfected cells (P<0.01), and the IC_(50) value of cisplatin on screened A498 cells was significantly decreased by 83.37% (P<0.01). Conclusion: The RNAi could effectively inhibit the expression of MDR1 gene and increase the sensibility to cisplatin in human renal carcinoma A498 cell line, which make it possible to reverse the resistance of renal carcinoma to chemotherapy.

The proliferative effect on silencing of endogenetic mdr1 gene expression by RNA interference in ovarian cancer resistant strain SKOV3/TAXOL / 肿瘤研究与临床

Objective To construct the short hairpin RNA recombinant plasmids targeting mdr1 gene which expresses highly in ovarian cancer resistance strain SKOV3/TAXOL to silence endogenefic mdr1 gene expression and investigate the role of mdr1 gene in the development of resistant ovarian cancer. Methods The pGPU6/GFP/Neo-mdr1 were constructed by gene clone technology. The influence on proliferation and apoptosis were investigated by CCK-8 in SKOV3/TAXOL after transfected pGPU6/GFP/Neo-mdr1. Results The expression against mdr1 proteins were inhibited by pGPU6/GFP/Neo-mdr1. The cell proliferation were inhibited after transfected pGPU6/GFP/Neo-mdr1 by CCK-8. The apoptosis were observed in DAB experiments and the apoptosis rate increased. Conclusion mdr1 plays an important role in proliferation of resistant ovarian cancer and the short hairpin RNA of mdr1 can efficiently suppress mdr1 expression and enhance the apoptosis in SKOV3/ATAXOL.

Expression of MAGE-A3 Gene and MDR1 Gene in Non M3-subtype Acute Leukemia and their correlations to dinical treatment efficacy / 中国医师杂志

Objective To evaluate the clinical value of co-observation of the expression of MAGE-A3 gene and MDR1 gene on esti-mating the curative effect in non M3-subtype acute leukemia. Methods Expressions of MAGE-A3 and MDRI were measured in 77 patients with non M3-subtype acute leukemia by RT-PCR method. Clinical observation was done to estimate the relationship between the genes with curative effect in non M3-subtype acute leukemia. Results Expression of MAGE-A3 and MDRI gene were 50. 6% and 23. 3% in non M3-subtype acute leukemia patients. Positive expression of MDRI in MAGE-A3-positive and negative patients were 46. 2% and 13. 2% (P < 0.01). The complete remission rate in MAGE-A3 negative and positive patients were 86. 8% and 64. I% (P <0. 05). Complete remission (CR) rate in MDR1 negative and positive patients was 83.3% and 56. 5% (P <0. 05). Complete remission rate were 87.9% and 55.6% in beth negative and both positive expression of MAGE-A3 and MDR1 (P < 0. 05). Conclusion The patients of positive expression of MAGE-A3 in non M3-subtype AL had higher expression of MDR1. The patients with negative expression of beth MAGE-A3 and MDR1 had higher CR rate than that in both positive patients. These researches indicated that eo-observatian of the expression of MAGE-A3 and MDR1 can predict the curative effect in non M3-subtype AL.

Investigation and its clinical significance of the relative activity of multidrug resistance P-glycoprotein in the plasma of breast cancer patients / 肿瘤研究与临床

Objective To investigate the relative activity of multidrug resistance P-glycoprotein in the plasma of breast cancer patients, analyze the expression of P-glycoprotein before and after chemotherapy and evaluate its clinical value. Methods The plasma of patients and chemical reagents were mixed and distributed into the 96-well plate. The plate was read at 340 nm absorbaace before and after reaction. The variation of absorbance for each well was calculated, and then relative activity of each sample was compared to the referent compound activity. The relative activity of over 30 % was taken as positive expression of the P-gp for each sample. Results The frequency of P-glycoprotein expression was significantly increased from 16.2 % before chemotherapy to 43.2 % after chemotherapy (P<0.05). The positive expression of P-glycoprotein before and after chemotherapy were 5/6 and 9/16, respectively, in patients with positive lymph node metastasis, and 1/6 and 7/16, respectively, in patients with negative lymph node metastasis. Conclusion The results of this preliminary study suggest in P-glycoprotein expression in plasma of patients play an important role in the selection of drugs, which may be useful to evaluate the prognosis for treatment of breast cancer patients.

The significance of quantification of MDR1 and WT1 gene expression in acute myeloid leukemia / 中华内科杂志

Objective To study the quantification of MDR1 and WT1 gene expression in patients with de novo acute myeloid leukemia(AML)and to explore the role of these two genes in clinical drug resistance and their correlation with risk stratification. Methods A real time quantitative reverse transcriptase polymerase chain reaction method was established for detecting MDR1 and WT1 gene expression levels in 63 de novo AML patients.Resuits The expression of WT1 and MDR1 was significantly higher in de novo AML patients than in normal controls (P＜0.001).WT1 levels were significantly correlated with corresponding levels of MDR1 gene in de novo AML patients(P=0.004).Expression levels of WT1 and MDR1 gene were not associated with FAB subtype and risk stratication(P＞0.05).AML patients with FLT3-ITD mutations had a significantly higher WT1 expression level as compared to with those without(P＜0.05),on the contrary MDR1 expression was not associated with FLT3-ITD mutations(P＞0.05).Patients with co-expression of high levels of WT1 and MDR1 had a significantly lower complete remission rate after induction therapy than those with low levels(P＜0.05).Conclusion There is a positive correlation between MDR1 gene expression and WT1 gene expression in AML.Quantification of the two gene expression together is more effective for judgement of prognosis in AML.

Progression of research of MDR1 single nucleotide polymorphism / 国际肿瘤学杂志

P-glycoprotein(P-gp),the product of multidrug resistance gene MDR1,plays a very significant role in the ADME processes(absorption,distribution,metabolism,excretion)and drug-drug interaction of drugs in human.The magnitude of resistance depends on the expression of MDR1 up-regulated by chemotherapy.DNA sequence differences ale associated with phenotypic variation by various mechanisms,single-nucleotide polymorphisms(SNPs)is the most common of them.Genetic polymorphisms of MDR1 are associated with alteration in P-gp expression and function in different ethnicities and subjects.

Establishment of multidrug resistance cell line of human bladder tumor T24/ADM and the expression analysis of mechanism of multidrug resistance / 肿瘤研究与临床

Objective To establish a multidrug resistance cell line of human bladder tumor and study its characteristics and mechanism of muhidrug resistance. Methods Human bladder tumor cell line T24 was induced to muhidrug resistance cell line T24/ADM by intermittent administration of high dose ADM. The multidrug resistance to multianticancer agents of the ceils was evaluated by MTT assay; the expression of MDR gene was assessed by RT-PCR and P-gp expression was determined by flow cytometry. Results T24/ ADM resisted to many anti-tumor agents, and its IC50 of ADM was 16.3 times higher than that of T24. Significant overexpression of MDR gene and p-gp of the multidrug resistant cells were detected. Conclusion T24/ADM is a human muhidrug-resistant cell line, and it's drug resistance relates to the overexpression of MDR gene and p-gp.

Detection of class Ⅰ integron in multi-resistant Enterobacter cloacae / 国际检验医学杂志

Objective To investigate the distribution and effect of class Ⅰ integron in 40 strains of clinical multi-resistant Enterobacter cloacae. Methods Kirby-Bauer method was used to analyze the drug resistance of 40 strains of multi-resistant Enterobacter cloacae and the drug resistance gene was analyzed by polymerase chain reaction (PCR). Results 28 strains (70.0%) of 40 clinical isolates were observed to contain class Ⅰ integron. Drug resistance test showed their resistance rate to 10 kind of an-tibaeterials as follow: 7.5% to imipenem, 5.0% to meropenem, 75.0% to piperacillin-tazobactam,55.0% to amikacin, 12.5% to cefepime, 52.5% to ceftazidime, 55.0% to cefotaxime, 90.0% to ceftriaxone;81.8% to ticarcillin-clavutanic acid, and 85.0% to ciprofloxacin. Conclusion This study shows that the resistance situation of Enterobacter cloacae isolates is very serious, and class Ⅰ integron may play an important role in the muhidrug resistant mechanism.

Expressions of C-erbB-2,Nm23 and MDR1 in primary breast cancer and their relations with metastasis and prognosis / 吉林大学学报(医学版)

0.05).The metastasis rate in patients with both C-erbB-2(+) and MDR1(+) was higher than the others.Their prognosis was negative.The metastasis rate in patients with both C-erbB-2(+) and Nm23(-) was higher than the others.Conclusion There are correlation between C-erbB-2,Nm23,MDR1 expressions and metastasis of breast cancer.Multi-predictors are better guide to patients than single predictor.

Expression of protein kinase C in multidrug resistant cells of colorectal carcinoma / 吉林大学学报(医学版)

Objective To detect the expression of protein kinase C(PKC) in multidrug resistant cells of colorectal carcinoma after ionizing irradiation and observe the effect of PKC on occurrence and development of the multidrug resistant.Methods The effect of PKC on multidrug resistant HCG-8 cells of colorectal carcinoma after treated with X-ray was detected by indirect immunofluorescence technique and flow cytometry.Results Compared with sham-irradiation group,the positive percentage of PKC was increased significantly(P

Prognostic Significance of Multidrug Resistance Gene 1 (MDR1), Multidrug Resistance-related Protein (MRP) and Lung Resistance Protein (LRP) mRNA Expression in Acute Leukemia

The prognostic significance of multidrug resistance (MDR) gene expression is controversial. We investigated whether multidrug resistance gene 1 (MDR1), multidrug resistance-related protein (MRP) and lung resistance protein (LRP) mRNA expression are associated with outcomes in acute leukemia patients. At diagnosis we examined MDR1, MRP and LRP mRNA expression in bone marrow samples from 71 acute leukemia patients (39 myeloid, 32 lymphoblastic) using nested RT-PCR. The expression of each of these genes was then expressed as a ratio in relation to beta-actin gene expression, and the three genes were categorized as being either 0, 1+, 2+ or 3+. MDR1, MRP and LRP mRNA expression was detected in 23.9%, 83.1% and 45.1 %, respectively. LRP mRNA expression was significantly associated with resistance to induction chemotherapy in acute leukemia patients, and in the AML proportion (p=0.02 and p=0.03, respectively). MRP and high MDR1 mRNA expression was associated with poorer 2-yr survival (p=0.049 and p=0.04, respectively). Patients expressing both MRP and LRP mRNA had poorer outcomes and had worse 2-yr survival. The present data suggest that MDR expression affects complete remission and survival rates in acute leukemia patients. Thus, determination of MDR gene expression at diagnosis appears likely to provide useful prognostic information for acute leukemia patients.

Relationship between MDR1 exon 26 genotype and dosage of FK506 and acute rejection following renal transplantation / 中华器官移植杂志

Objective To evaluate whether the MDR1 exon 26 genotype is associated with the dosage of FK506 and acute rejection in renal transplant patients. Methods One hundred and six patients who administrated FK506 after renal transplantation were retrospectively analyzed. The patients were investigated for MDR1 genotype determined by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) assays. According to the genotype, the patients were divided into 3 subgroups, wild homozygous-CC, mutant homozygous-TT and heterozygous-CT. At 3rd, 6th and 12th month after renal transplantation, enzyme-linked immunosorbent assay (ELISA) was used to measure the FK506 whole blood concentration. Whole blood FK506 concentration per dose/kg/day and acute rejection within one month postoperation were compared among 3 subgroups. Results Of the 106 patients, 32 (30.2 %), 44 (41.5 %) and 30 (28.3 %) were carriers of CC, CT, TT in MDR1 exon 26, respectively. The whole blood FK506 concentration per dose/kg/day for patients with CC was remarkably lower that that of the patients with either CT or TT (P

Antiepileptic drug-induced overexpression of P-glycoprotein multidrug resistance gene in astrocytes in vitro / 中华神经科杂志

Objective To study the overexpression of antiepileptic drug (AED) induced P glycoprotein multidrug resistance gene in astrocytes in vitro Methods Postnatal Wistar rats (within 24 h) astrocyte cell culture was performed. Different concentrations of phenytoin (PHT),phenobarbitone (PB),carbamazepine (CBZ),valproate (VPA) were added to the culture media for 10,20 and 30 days The overexpression of P glycoprotein (Pgp) multidrug resistance gene was investigated with the immunocytochemistry method Results The Pgp staining of normal astrocytes was less than 5% at each time point The Pgp positive staining was found in 20 mg/L PB,40 mg/L PB,20 mg/L PHT at the 30 day There were overexpressions at the 20 and 30 day, excluding CBZ at 20 day in the higher concertration of the four AED Conclusion AED may induce the overexpression of Pgp,which is correlated with the dose and time