DETECTION OF CARBAPENEMASE PRODUCING ENTEROBACTERALES AMONG THE CLINICAL ISOLATES OF DIARRHOEAGENIC ESCHERICHIA COLI CAUSING ACUTE GASTROENTERITIS IN CHILDREN BELOW 2 YEARS IN TERTIARY CARE HOSPITAL OF NORTH EAST INDIA.

Introduction: Enterobacterales that test resistant to at least one of the carbapenem antibiotics (ertapenem, meropenem, doripenem, or imipenem) are called Carbapenem resistant Enterobacterales (CRE) and if they produce a carbapenemase (an enzyme that can make them resistant to carbapenem antibiotics) they are called Carpenemase producing Enterobacterales (CPE). Children with CRE strains in fecal samples are considered as a high risk group by World Health Organization (WHO), which can spread CRE by intimate contact and travel. This cross-sectional study was conducted in the Departm Methods: ent of Microbiology, RIMS, Imphal, Manipur, India from Jan 2020 to Feb 2022. A total of 157 children under 2 years of age whose stool culture was positive for diarrhoeagenic Escherichia coli were included in the study. The modified carbapenem inactivation method (mCIM) has been done for detection of carbapenemase producers and the addition of EDTA in eCIM to further differentiate between serine and metallo-?-lactamase producers. Out of 157 Result and Discussion: Diarrhoegenic E.coli (DEC) ,Carbapenem resistance was seen in 9 isolates i.e 5.7 %. Out of these 9 isolates, 3 were MBL producers tested by the phenotypic test mCIM and eCIM. All the three MBL producers carried bla NDM-1 gene. mCIM/eCIM assay is designed to simultaneously detect and distinguish the different types of carbapenemases. Carbapenemase genes are often located on plasmids that can be exchanged between Enterobacteriaceae and other Gram-negative bacteria. Carbapenem-resistant K. pneumoniae are currently more frequent and more likely to cause healthcareassociated outbreaks, carbapenem-resistant E. coli pose a greater risk for spread in the community. Conclusion: Screening for carbapenemase producer using mCIM and eCIM essay is important along with infection control measure such as active surveillance through rectal screening for CRE carriage on hospital admission, contact precautions, hand hygiene, patient isolation, environmental sanitation, case notification/fiagging, antibiotic restriction.

A point-prevalence survey of carbapenem-resistant Enterobacteriaceae in two different cities in Kuwait and Nigeria

Background: The family Enterobacteriaceae belongs to the order Enterobacterales, a large diverse group of Gramnegative, facultatively anaerobic bacteria that sometimes cause multidrug-resistant infections which treatment options are often challenging. They are the leading cause of nosocomial bloodstream infection (BSI) and urinary tract infections (UTI). The objective of the study was to carry out a point-prevalence survey of antimicrobial resistance and carbapenem-resistant Enterobacteriaceae (CRE) clinical isolates in two hospitals in Kuwait and Nigeria. Methodology: Clinically significant bacterial isolates of patients from Kuwait and Nigeria, identified by VITEK-2 and MALDI-TOF mass spectrometry analysis were studied. Susceptibility testing of selected antibiotics was performed using E-test and broth dilution methods. Genes encoding carbapenemase, ß-lactamases, and extended-spectrum ßlactamases (ESBLs) were detected by conventional PCR and sequencing, and whole genome sequencing (WGS) analyses. Results: Of 400 isolates from Kuwait and Nigeria, 188 (47.0%) and 218 (54.5%) were Escherichia coli and 124 (31.0%) and 116 (29.0%) Klebsiella pneumoniae, respectively. The prevalence of CRE was 14.0% in Kuwait and 8.0% in Nigeria. The resistance rates of CRE isolates against colistin and tigecycline in Kuwait were 6.6% versus 25.0%, and in Nigeria were 14.2% versus 14.2%, respectively. blaOXA-181 gene was the commonest in CRE isolates in Kuwait and blaNDM-7 in Nigeria. The commonest ESBL gene among the CRE isolates was blaCTX-M-15 in both countries. AmpC resistance genes were present in only Kuwait isolates and mediated by blaEBC, blaCIT and blaDHA. WGS analysis of 12 selected CRE isolates with carbapenem MICs>32µg/ml but no detectable genes from conventional PCR, revealed the presence of multidrug efflux pump genes such as major facilitator superfamily antibiotic efflux pump and resistance-nodulation-cell division antibiotic efflux pump groups. Conclusion: The prevalence of CRE was higher among isolates from Kuwait than Nigeria and the genes encoding resistance in CRE were different. The presence of efflux pump was a main mechanism of resistance in most of the Nigerian CRE isolates.

Effect of Rheb1 in the Development of Mouse Megakaryocyte-Erythroid Progenitor Cells / 中国实验血液学杂志

OBJECTIVE@#To investigate the effect of Rheb1 in the development of mouse megakaryocyte-erythroid progenitor cells and its related mechanism.@*METHODS@#Rheb1 was specifically knocked-out in the hematopoietic system of Vav1-Cre;Rheb1fl/fl mice(Rheb1Δ/Δ mice). Flow cytometry was used to detect the percentage of red blood cells in peripheral blood and erythroid cells in bone marrow in Vav1-Cre;Rheb1fl/fl mice and control mice. The CFC assay was used to detect the differentiation ability of Rheb1 KO megakaryocyte-erythroid progenitor cells and control cells. Real-time fluorescence quantification PCR was used to detect the relative expression of PU.1,GATA-1,GATA-2,CEBPα and CEBPβ of Rheb1 KO megakaryocyte-erythroid progenitor cells and control cells. Rapamycin was added to the culture medium, and it was used to detect the changes in cloning ability of megakaryocyte-erythroid progenitor cells from wild-type mice in vitro.@*RESULTS@#After Rheb1 was knocked out, the development and stress response ability of megakaryocyte-erythroid progenitor cells in mice were weaken and the differentiation ability of megakaryocyte-erythroid progenitor cells in vitro was weaken. Moreover, the expression of GATA-1 of megakaryocyte-erythroid progenitor cells was decreased. Further, rapamycin could inhibit the differentiative capacity of megakaryocyte-erythroid progenitor cells in vitro.@*CONCLUSION@#Rheb1 can regulate the development of megakaryocyte-erythroid progenitor cells probably through the mTOR signaling pathway in mice.

Chemo-photothermal immunotherapy for eradication of orthotopic tumors and inhibition of metastasis by intratumoral injection of polydopamine versatile hydrogels

Cancer remains one of the leading causes of death globally and metastasis always leads to treatment failure. Here, we develop a versatile hydrogel loading photothermal agents, chemotherapeutics, and immune-adjuvants to eradicate orthotopic tumors and inhibit metastasis by combinational therapy. Hydrogel networks were synthesized via the thiol-Michael addition of polydopamine (PDA) with thiolated hyaluronic acid. PDA acted as a cross-linking agent and endowed the hydrogel with excellent photothermal property. Meanwhile, a chemotherapeutic agent, doxorubicin (DOX), was loaded in the hydrogel via π‒π stacking with PDA and an immune-adjuvant, CpG-ODN, was loaded via electrostatic interaction. The release of DOX from the hydrogel was initially slow but accelerated due to near infrared light irradiation. The hydrogels showed remarkably synergistic effect against 4T1 cancer cells and stimulated plenty of cytokines secreting from RAW264.7 cells. Moreover, the hydrogels eradicated orthotopic murine breast cancer xenografts and strongly inhibited metastasis after intratumoral injection and light irradiation. The high anticancer efficiency of this chemo-photothermal immunotherapy resulted from the strong synergistic effect of the versatile hydrogels, including the evoked host immune response. The combinational strategy of chemo-photothermal immunotherapy is promising for highly effective treatment of breast cancer.

Mechanism of Chuanxiong Rhizoma intervention on central sensitization of Panx1-Src-NMDAR-2B signaling pathway in neuropathic pain model rats / 中国中药杂志

Excitatory toxicity(ET) is an important factor of neuropathic pain(NPP) induced by central sensitization(CS), and the association of pannexin-1(Panx1)-Src-N-methyl-D-aspartate receptor subunit 2 B(NMDAR-2 B) is an important new pathway for ET to initiate CS. The present study confirmed whether the central analgesic effect of Chuanxiong Rhizoma extract(CRE) was achieved through the synchronous regulation of the brain and spinal pathways of Panx1-Src-NMDAR-2 B. In this study, dynamic and simulta-neo-us microdialysis of the brain and spinal cord in vivo combined with behavioristics, high performance liquid chromatography(HPLC)-fluorescence detection, microdialysis analysis(ISCUS~(flex)), ultrasensitive multifactorial electrochemiluminescence immunoassay, ELISA, and Western blot was employed to investigate the protein expression of NMDAR-2 B, Src, and Panx1, extracellular excitatory amino acids, cytokines, energy metabolites, and substance P in spinal dorsal horn(SDH) and anterior cingulate cortex(ACC) after CRE intervention with the rat model of spared sciatic nerve injury(SNI) as the experimental tool. Compared with the sham group, the SNI group exhibited diminished mechanical withdrawal threshold(MWT)(P<0.01), increased cold spray scores(P<0.01), glutamate(Glu), D-serine(D-Ser), and glycine(Gly) in extracellular fluids of ACC, and Glu, D-Ser, interleukin-1β(IL-1β), and lactic acid(Lac) in extracellular fluids of SDH(P<0.05), dwindled tumor necrosis factor(TNF-α)(P<0.05), and elevated protein levels of NMDAR-2 B, Src, and Panx1 in ACC(P<0.05). Compared with the SNI model rats, high-and medium-dose CRE(CRE-H/M) could potentiate the analgesic activity as revealed by the MWT test(P<0.05) and CRE-M enabled the decrease in cold spray scores(P<0.05). CRE-H/M could inhibit the levels of Glu, D-Ser and Gly in the extracellular fluids of ACC(P<0.05), and the levels of Glu in the extracellular fluids of SDH(P<0.05) in SNI rats. CRE-M significantly increased the levels of glucose(Gluc), Lac, interferon-gamma(IFN-γ), keratinocyte chemoattractant/human growth-regulated oncogenes(KC/GRO), and IL-4 in extracellular fluids of SDH in SNI rats(P<0.05). CRE-H/M/L could also inhibit the levels of NMDAR-2 B, Src and Panx1 in ACC and SDH in SNI rats(P<0.05). The central analgesic effect of CRE is presumedly related to the inhibited release of excitatory amino acid transmitters(Glu, D-Ser and Gly) in ACC and SDH of SNI rats, decreased protein expression of NMDAR-2 B, Src and Panx1 in the two regions, and the regulation of the Panx1-Src-NMDAR-2 B pathway in the spinal cord and brain. The above findings partially clarified the scientific basis of clinical analgesic effect of Chuanxiong Rhizoma.

Pure photosensitizer-driven nanoassembly with core-matched PEGylation for imaging-guided photodynamic therapy

Pure drug-assembled nanomedicines (PDANs) are currently under intensive investigation as promising nanoplatforms for cancer therapy. However, poor colloidal stability and less tumor-homing ability remain critical unresolved problems that impede their clinical translation. Herein, we report a core-matched nanoassembly of pyropheophorbide a (PPa) for photodynamic therapy (PDT). Pure PPa molecules are found to self-assemble into nanoparticles (NPs), and an amphiphilic PEG polymer (PPa-PEG

Antibiotic resistance profile in intrahospital pediatric services at third level centers in Dominican Republic / Perfil de resistencia a antibióticos en servicios pediátricos intrahospitalarios en centros de tercer nivel en República Dominicana

Objectives: The Dominican Republic lacks reliable information on antimicrobial resistance (AMR), which would allow physicians to prescribe the best treatment for common infectious diseases. This study aimed to define the antimicrobial resistance profiles of the more common pathogens from pediatric services, where data is even more important due to the vulnerability of the population. Methods: We collected data from patients admitted in the pediatric unit of three third level hospitals in the city of Santiago de los Caballeros, Dominican Republic, showing positive bacterial cultures, during a period of two years. Results: Half of the Gram negative pathogens exhibited third generation cephalosporins (3GC) resistance, 17% were resistant to carbapenems. Serratia marcescens presented an exceptionally high proportion of resistance to 3GC (95.9%). Staphylococcus aureus showed elevated resistance to methicillin (58.4%) and even to clindamycin (35.8%). Conclusion: There are elevated levels of antimicrobial resistance among the Enterobacteriaceae family and the Staphylococcus genus isolated from the pediatric population. Necessary measures should be taken to tackle AMR in the country.

Objetivos: La República Dominicana carece de información confiable sobre las resistencias antimicrobianas en el país, lo que permitiría al personal médico prescribir los mejores tratamientos para infecciones comunes. El objetivo de este estudio es definir los perfiles de resistencia antimicrobiana de los patógenos más comunes en servicios pediátricos, donde esta información es esencial, debido a la vulnerabilidad de la población. Métodos: Se tomaron los datos de reportes microbiológicos con cultivo bacteriano positivo procedentes de pacientes admitidos en la unidad pediátrica de tres hospitales de tercer nivel en la ciudad de Santiago de los Caballeros, República Dominicana, durante un periodo de dos años. Resultados: La mitad de los patógenos Gram negativos mostraron resistencia a cefalosporinas de tercera generación (3GC), 17% eran resistentes a carbapenémicos. Serratia marcescens presentó una resistencia excepcionalmente elevada a 3GC (95.9%). Staphylococcus aureus mostró alta resistencia a meticilina (58.4%) e incluso a clindamicina (35.8%). Conclusión: Existen elevados niveles de resistencia antimicrobiana entre las enterobacterias y los estafilococos en la población pediátrica dominicana. Es necesario tomar medidas para abordar este problema en el país.

Celsr3 is required in mouse hippocampal intrinsic wiring and spatial learning

Background The atypical cadherin Celsr3, which belongs to the core planar cell polarity group, orchestratesaxonal guidance and network wiring. Previous work using regional inactivation of Celsr3 in forebrain showedthat Celsr3 is widely involved in hippocampal maturation and connectivity. However, inactivation in the wholeforebrain does not provide sufficient specificity to address the function of Celsr3 in detail.Method We studied the Celsr3|Emx1 mouse mutant model, in which Celsr3 is selectively inactivated inhippocampal projection neurons, but not in entorhinal cortex, basal ganglia and interneurons.Result In that mutant, the hippocampal cytoarchitecture was almost normal. Inactivation of Celsr3 inprojection neurons perturbed intrinsic hippocampal wiring. Consistent with wiring defects, Celsr3|Emx1mutant mice showed impaired learning and memory, and were less anxiety-prone than control mice.Conclusion Celsr3|Emx1 mutant mice provide a simple way to study the consequences of defectivehippocampal wiring in absence of drastic structural anomalies.

Engineering CrtW and CrtZ for improving biosynthesis of astaxanthin in Escherichia coli / 中国天然药物

This study engineered β-carotene ketolase CrtW and β-carotene hydroxylase CrtZ to improve biosynthesis of astaxanthin in Escherichia coli. Firstly, crtW was randomly mutated to increase CrtW activities on conversion from β-carotene to astaxanthin. A crtW* mutant with A6T, T105A and L239M mutations has improved 5.35-fold astaxanthin production compared with the wild-type control. Secondly, the expression levels of crtW* and crtZ on chromosomal were balanced by simultaneous modulation RBS regions of their genes using RBS library. The strain RBS54 selected from RBS library, directed the pathway exclusively towards the desired product astaxanthin as predominant carotenoid (99%). Lastly, the number of chromosomal copies of the balanced crtW-crtZ cassette from RBS54 was increased using a Cre-loxP based technique, and a strain with 30 copies of the crtW*-crtZ cassette was selected. This final strain DL-A008 had a 9.8-fold increase of astaxanthin production compared with the wild-type control. Fed-batch fermentation showed that DL-A008 produced astaxanthin as predominant carotenoid (99%) with a specific titer of 0.88 g·L without addition of inducer. In conclusion, through constructing crtW mutation, balancing the expression levels between crtW* and crtZ, and increasing the copy number of the balanced crtW*-crtZ cassette, the activities of β-carotene ketolase and β-carotene hydroxylase were improved for conversion of β-carotene to astaxanthin with higher efficiency. The series of conventional and novel metabolic engineering strategies were designed and applied to construct the astaxanthin hetero-producer strain of E. coli, possibly offering a general approach for the construction of stable hetero-producer strains for other natural products.

Expression Patterns of Inducible Cre Recombinase Driven by Differential Astrocyte-Specific Promoters in Transgenic Mouse Lines / 神经科学通报·英文版

Astrocytes are the most abundant cell type in the central nervous system (CNS). They provide trophic support for neurons, modulate synaptic transmission and plasticity, and contribute to neuronal dysfunction. Many transgenic mouse lines have been generated to obtain astrocyte-specific expression of inducible Cre recombinase for functional studies; however, the expression patterns of inducible Cre recombinase in these lines have not been systematically characterized. We generated a new astrocyte-specific Aldh1l1-CreER knock-in mouse line and compared the expression pattern of Cre recombinase between this and five widely-used transgenic lines (hGfap-CreER from The Jackson Laboratory and The Mutant Mouse Resource and Research Center, Glast-CreER, Cx30-CreER, and Fgfr3-iCreER) by crossing with Ai14 mice, which express tdTomato fluorescence following Cre-mediated recombination. In adult Aldh1l1-CreER:Ai14 transgenic mice, tdTomato was detected throughout the CNS, and five novel morphologically-defined types of astrocyte were described. Among the six evaluated lines, the specificity of Cre-mediated recombination was highest when driven by Aldh1l1 and lowest when driven by hGfap; in the latter mice, co-staining between tdTomato and NeuN was observed in the hippocampus and cortex. Notably, evident leakage was noted in Fgfr3-iCreER mice, and the expression level of tdTomato was low in the thalamus when Cre recombinase expression was driven by Glast and in the capsular part of the central amygdaloid nucleus when driven by Cx30. Furthermore, tdTomato was clearly expressed in peripheral organs in four of the lines. Our results emphasize that the astrocyte-specific CreER transgenic lines used in functional studies should be carefully selected.

Performance Evaluation of the CRE2 Reagent from Siemens for Serum Creatinine Measurement

BACKGROUND: For creatinine measurement, the enzymatic method is known to be more accurate than the Jaffe method; however, the latter is still widely used. We evaluated the performance of the CRE2 reagent (Siemens Healthcare Diagnostics Inc., USA), which uses a modified Jaffe method. METHODS: Three quality control standards were used for precision evaluations of CRE2 on Dimension VISTA 500 instrument (Siemens). Moreover, the linearity and carryover characteristics were assessed. Sixty-eight creatinine results obtained using the CRE2 and ECREA (enzymatic) reagents (Siemens) were compared with those obtained using the L-CRE (enzymatic) reagent (Shinyang Diagnostics, Korea). The accuracy of CRE2, ECREA, and L-CRE was evaluated using a standard reference material. RESULTS: The CV of within-run (0.7–2.4%), between-run (0.4–1.7%), between-day precision (0.7–0.9%) for three standards, and total CV for medium (1.6%) and high levels (1.3%) satisfied the analytical goal. The linearity for CRE2 was excellent (R2=0.999). Comparisons of CRE2 and ECREA to L-CRE were well correlated (r=0.996 and 0.997, respectively). In comparison with L-CRE, 5 CRE2 results and 15 ECREA results exceeded minimum bias goal (5.1%) in samples with creatinine levels of >1 mg/dL. The carryover rate was −0.04%. In terms of accuracy, the percent bias values of CRE2, ECREA, and L-CRE were 7.4, −6.4, and −3.4, respectively, for low level; and 3.9, −1.5, and 0.7, respectively, for high level. CONCLUSIONS: For creatinine measurements, the CRE2 reagent showed good performance. It can be used in the diagnosis, treatment monitoring, and risk assessment of kidney diseases.

Research progress of Cre/LoxP system in the eyes of animal model / 中华实验眼科杂志

Cre/LoxP system has been widely used as new type of gene targeting, which can transform genes in specific tissues and organs, remove specific gene fragments, and help to study the effects of specific genes on growth and development.Cre/LoxP system is the core technology of conditional gene targeting, which induces gene targeting, and spatiotemporal specific gene targeting.The resource about the mechanism of the Cre/LoxP system is helpful to obtain the Cre transgenic mouse model on different cell types of the retina.The Cre transgenic mice with specific expression in retinal bipolar cells and ganglion cells can provide the experimental basis for the absence of specific tissue single genes during growth and development.This review focused on the Cre/LoxP system and specific Cre recombinase mouse model in eyes.

Construction and identification of mouse model with conditional knockout of p75 neurotrophin receptor gene in epidermal cells by Cre-loxP system / 中华烧伤杂志

Objective@#To construct and identify a mouse model with conditional knockout (cKO) of p75 neurotrophin receptor (p75NTR-cKO) gene in epidermis cells by Cre-loxP system.@*Methods@#Five p75NTRflox/flox transgenic C57BL/6J mice (aged 6-8 weeks, male and female unlimited, the age and sex of mice used for reproduction were the same below) and five keratin 14 promotor-driven (KRT14-) Cre+ /- transgenic C57BL/6J mice were bred and hybridized via Cre-loxP system. Five p75NTRflox/+ ·KRT14-Cre+ /- mice selected from the first generation of mice were mated with five p75NTRflox/flox mice to obtain the second generation hybrids. After the second generation mice were born 20-25 days, the parts of the mice tail were cut off to identify the genotype by polymerase chain reaction method. Four p75NTR gene complete cKO mice (6 weeks old) and 4 wild-type mice (6 weeks old) were selected and sacrificed respectively. The abdominal skin tissue and brain tissue were excised to observe the expression of p75NTR in the two tissue of two types of mice by immunohistochemical staining. The abdominal skin tissue of two types of mice was obtained to observe the histomorphological changes by hematoxylin and eosin staining.@*Results@#(1) Twenty second generation mice were bred. The genotype of 4 mice was p75NTRflox/flox·KRT14-Cre+ /-(p75NTR-/-), i. e. p75NTR gene complete cKO mice; the genotype of 5 mice was p75NTRflox/+ ·KRT14-Cre+ /-, i. e. p75NTR gene partial cKO mice; the genotype of 5 mice was p75NTRflox/flox·KRT14-Cre-/-, and that of 6 mice was p75NTRflox/+ ·KRT14-Cre-/-, all of which were wild-type mice. (2) The expression of p75NTR was negative in skin epidermis tissue of p75NTR gene complete cKO mice, while numerous p75NTR positive expression was observed in skin epidermis tissue of wild-type mice. Abundant p75NTR positive expression was observed in brain tissue of both wild-type mice and p75NTR gene complete cKO mice. (3) There was no abnormal growth of skin epidermis tissue in both wild-type mice and p75NTR gene complete cKO mice, with intact hair follicle structure.@*Conclusions@#Applying Cre-loxP system can successfully construct a p75NTR-cKO mice model in epidermis cells without obvious changes in skin histomorphology.

Research progress of Cre/LoxP system in the eyes of animal model / 中华实验眼科杂志

Cre/LoxP system has been widely used as new type of gene targeting,which can transform genes in specific tissues and organs,remove specific gene fragments,and help to study the effects of specific genes on growth and development. Cre/LoxP system is the core technology of conditional gene targeting,which induces gene targeting, and spatiotemporal specific gene targeting. The resource about the mechanism of the Cre/LoxP system is helpful to obtain the Cre transgenic mouse model on different cell types of the retina. The Cre transgenic mice with specific expression in retinal bipolar cells and ganglion cells can provide the experimental basis for the absence of specific tissue single genes during growth and development. This review focused on the Cre/LoxP system and specific Cre recombinase mouse model in eyes.

Cilastatin protects against imipenem-induced nephrotoxicity inhibition of renal organic anion transporters (OATs)

Imipenem is a carbapenem antibiotic. However, Imipenem could not be marketed owing to its instability and nephrotoxicity until cilastatin, an inhibitor of renal dehydropeptidase-I (DHP-I), was developed. In present study, the potential roles of renal organic anion transporters (OATs) in alleviating the nephrotoxicity of imipenem by cilastatin were investigated and in rabbits. Our results indicated that imipenem and cilastatin were substrates of hOAT1 and hOAT3. Cilastatin inhibited hOAT1/3-mediated transport of imipenem with IC values comparable to the clinical concentration, suggesting the potential to cause a clinical drug-drug interaction (DDI). Moreover, imipenem exhibited hOAT1/3-dependent cytotoxicity, which was alleviated by cilastatin and probenecid. Furthermore, cilastatin and probenecid ameliorated imipenem-induced rabbit acute kidney injury, and reduced the renal secretion of imipenem. Cilastatin and probenecid inhibited intracellular accumulation of imipenem and sequentially decreased the nephrocyte toxicity in rabbit primary proximal tubule cells. Renal OATs, besides DHP-I, was also the target of interaction between imipenem and cilastatin, and contributed to the nephrotoxicity of imipenem. This therefore gives in part the explanation about the mechanism by which cilastatin protected against imipenem-induced nephrotoxicity. Thus, OATs can potentially be used as a therapeutic target to avoid the renal adverse reaction of imipenem in clinic.

Effect of polymyxin B-containing regimens on renal function for the treatment of carbapenem-resistant Enterobacteriacea mediastinitis

ABSTRACT A retrospective cohort study, were evaluated: polymyxin B plus aminoglycosides or polymyxin B plus other antibiotics. Any degree of acute kidney injury occurred in 26 (86.6%) patients. The median time to acute kidney injury was 6.0 (95% CI 3-14) days in the polymyxin-aminoglycoside containing regimen group, against 27.0 (95% CI 6-42) days in the polymyxin with other antimicrobial combinations group (p = 0.03). Polymyxin B with aminoglycosides group progressed faster to any degree of renal dysfunction.

Mouse Cre-LoxP system: general principles to determine tissue-specific roles of target genes / 한국실험동물학회지

Genetically engineered mouse models are commonly preferred for studying the human disease due to genetic and pathophysiological similarities between mice and humans. In particular, Cre-loxP system is widely used as an integral experimental tool for generating the conditional. This system has enabled researchers to investigate genes of interest in a tissue/cell (spatial control) and/or time (temporal control) specific manner. A various tissue-specific Cre-driver mouse lines have been generated to date, and new Cre lines are still being developed. This review provides a brief overview of Cre-loxP system and a few commonly used promoters for expression of tissue-specific Cre recombinase. Also, we finally introduce some available links to the Web sites that provides detailed information about Cre mouse lines including their characterization.

Astrocyte Specificity and Coverage of hGFAP-CreERT2 Tg(GFAP-Cre/ERT2)13Kdmc Mouse Line in Various Brain Regions

Astrocyte is the most abundant cell type in the central nervous system and its importance has been increasingly recognized in the brain pathophysiology. To study in vivo function of astrocyte, astrocyte-specific gene-targeting is regarded as a powerful approach. Especially, hGFAP-CreERT2, which expresses tamoxifen-inducible Cre recombinase under the human GFAP promoter, has been developed and characterized from several research groups. However, one of these mouse lines, [Tg(GFAP-Cre/ERT2)13Kdmc] from Ken McCarthy group has not been quantitatively analyzed, despite its frequent use. Here, we performed comprehensive characterization of this mouse line with quantitative analysis. By crossing this mouse line with Ai14 (RCL-tdTomato), a very sensitive Cre reporter mouse line, we visualized the Cre-expressing cells in various brain regions. For quantitative analysis, we immunostained S100β as an astrocytic marker and NeuN, tyrosine hydroxylase or calbindin as a neuronal marker in different brain regions. We calculated ‘astrocyte specificity’ as the proportion of co-labelled S100β and tdTomato positive cells in the total number of tdTomato positive cells and the ‘astrocyte coverage’ as the proportion of co-labelled S100β and tdTomato positive cells in the total number of S100β positive cells. Interestingly, we found varying degree of astrocyte specificity and coverage in each brain region. In cortex, hypothalamus, substantia nigra pars compacta and cerebellar Purkinje layer, we observed high astrocyte specificity (over 89%) and relatively high astrocyte coverage (over 70%). In striatum, hippocampal CA1 layer, dentate gyrus and cerebellar granule layer, we observed high astrocyte specificity (over 80%), but relative low astrocyte coverage (50–60%). However, thalamus and amygdala showed low astrocyte specificity (about 65%) and significant neuron specificity (over 30%). This hGFAP-CreERT2 mouse line can be useful for genetic modulations of target gene either in gain-of-function or loss-of-function studies in the brain regions with high astrocyte specificity and coverage. However, the use of this mouse line should be restricted to gain-of-function studies in the brain regions with high astrocyte specificity but low coverage. In conclusion, hGFAP-CreERT2 mouse line could be a powerful tool for gene-targeting of astrocytes in cortex, striatum, hippocampus, hypothalamus, substantia nigra pars compacta and cerebellum, but not in thalamus and amygdala.

Establishment of transgenic mice model with overexpression of neuritin in bone marrow / 实用医学杂志

Objective To establish transgenic mice model with over expression of neuritin in bone mar-row,for the further study on the function of neuritin protein in the treatment of peripheral neuropathy. Methods Two pairs of transgenic mice(loxp-stop-loxp-neuritin and lyz-Cre/+)were fed and propagated,the DNA from the mice tails extracted and the genotype of transgenic mice identified by PCR. The wild type mice with B6 were as-signed as the controls,and the immunofluorescence was used to detect the accuracy of the neuritinloxp/+ _lyz -Cre/+. Results The two trensgenetic homozygous mice had the ability to reproduce,and the hybrid offsprings were neuritinloxp/+_lyz-Cre/+,neuritinloxp/-_lyz-Cre/+,neuritinloxp/+_lyz-Cre/-,neuritinloxp/-_lyz-Cre/-. The re-sults were met with the Mendel′s law. The results of immunofluorescence showed that the expression of neuritin of neuritinloxp/+_lyz-Cre/+ mice in bone marrow was significantly higher than the wild type mice(P < 0.05). Con-clusion The PCR method is of high reliability for identification of sub pus genotype and the female neuritinloxp/+mice mating with the male lyz-Cre/+ ones is an effective way for obtaining the neuritinloxp/+_lyz-Cre/+ mice.

Construction and identification of conditional islet βcell DEPTOR knockout mice / 实用医学杂志

Objective To study the function of Deptor gene on the regulation of diabetes mellitus in suc-cessfully constructed and identified islet β-cell conditionally DEPTOR knockout mice model. Method By cross-breeding Deptorflox/floxmice with Cre mice expressed conditional specifically in pancreatic β-cell,Deptorflox/+Cre+/-mice were acquired and their genotypic identification was then performed. As the mice model of this study, Deptorflox/floxCre+/-mice were generated by crossing Deptorflox/+Cre+/-mice with Deptorflox/floxmice.Genotypic identifica-tion was performed by PCR at the age of 3 weeks. Tamoxifen was administered through intraperitoneal injection to induce the activation of the Cre recombination in islet beta cells of 8 weeks mice.Double immunofluorescence label-ing was then applied to identify the knockout effect of DEPTOR gene. Results Ten Islets Deptor knockout mice models were successfully acquired after 10-month cross-breeding. Validated genotype by PCR analysis were Deptorflox/floxCre+/- and double immunofluorescence labeling showed a significant difference between knockout mice and rodent controls. Conclusion Our study successfully constructs the islets conditionally Deptor deleted mice model by using Cre-loxp recombination system,providing a promising appliable animal model for study of dia-betes mellitus pathogenetic mechanism.