The Emerging Human Pathogen Photorhabdus asymbiotica Is a Facultative Intracellular Bacterium and Induces Apoptosis of Macrophage-Like Cells

ABSTRACT Photorhabdus species are gram-negative entomopathogenic bacteria of the family Enterobacteriaceae. Among the different members of the genus, one species, Photorhabdus asymbiotica, is a pathogen of both insects and humans. The pathogenicity mechanisms of this bacterium are unknown. Here we show that P. asymbiotica is a facultative intracellular pathogen that is able to replicate inside human macrophage-like cells. Furthermore, P. asymbiotica was shown for the first time in an intracellular location after insect infection. We also demonstrated that among Australian and American clinical isolates, only the Australian strains were able to invade nonphagocytic human cells. In cell culture infection experiments, Australian clinical isolates as well as cell-free bacterial culture supernatant induced strong apoptosis of a macrophage cell line at 6 h postinfection. American isolates also induced cellular death, but much later than that induced by Australian ones. Mammalian cultured cells analyzed for key features of apoptosis displayed apoptotic nuclear morphology, activation of the initiator caspases 8 and 9 and the executioner caspases 3 and 7, and poly(ADP-ribose) polymerase proteolysis, suggesting activation of both the intrinsic and extrinsic apoptotic pathways.

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Transcriptional Expression of the ompA, cpaf, tarp, and tox Genes of Chlamydia trachomatis Clinical Isolates at Different Stages of the Developmental Cycle

Microorganisms ◽

10.3390/microorganisms7060153 ◽

2019 ◽

Vol 7 (6) ◽

pp. 153 ◽

Cited By ~ 4

Author(s):

Suvi Korhonen ◽

Kati Hokynar ◽

Laura Mannonen ◽

Jorma Paavonen ◽

Eija Hiltunen-Back ◽

...

Keyword(s):

Gene Expression ◽

Chlamydia Trachomatis ◽

Cultured Cells ◽

Expression Patterns ◽

Clinical Isolates ◽

Gene Expression Patterns ◽

Developmental Cycle ◽

Passage Number ◽

Low Passage ◽

Reference Strains

The transcriptional gene expression patterns of Chlamydia trachomatis have mainly been studied using reference strains propagated in cultured cells. Here, using five low-passage-number C. trachomatis clinical isolates that originated from asymptomatic or symptomatic female patients, the in vitro expression of the ompA, cpaf, tarp, and tox genes was studied with reverse transcriptase real-time PCR during the chlamydial developmental cycle. We observed dissimilarities in the gene expression patterns between the low-passage-number clinical isolates and the reference strains. The expression of ompA and the peak of the tox expression were observed earlier in the reference strains than in most of the clinical isolates. The expression of cpaf was high in the reference strains compared with the clinical isolates at the mid-phase (6–24 hours post infection) of the developmental cycle. All of the strains had a rather similar tarp expression profile. Four out of five clinical isolates exhibited slower growth kinetics compared with the reference strains. The use of low-passage-number C. trachomatis clinical isolates instead of reference strains in the studies might better reflect the situation in human infection.

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A system to impose prescribed homogenous strains on cultured cells

Journal of Applied Physiology ◽

10.1152/jappl.2001.91.4.1600 ◽

2001 ◽

Vol 91 (4) ◽

pp. 1600-1610 ◽

Cited By ~ 24

Author(s):

Christopher M. Waters ◽

Matthew R. Glucksberg ◽

Eugene P. Lautenschlager ◽

Chyh-Woei Lee ◽

Reed M. Van Matre ◽

...

Keyword(s):

Epithelial Cells ◽

Cultured Cells ◽

Large Strain ◽

Mechanical Strain ◽

Airway Epithelial Cells ◽

Airway Epithelial ◽

Degree Of Anisotropy ◽

High Degree ◽

Membrane Shape ◽

First Time

There is presently significant interest in cellular responses to physical forces, and numerous devices have been developed to apply stretch to cultured cells. Many of the early devices were limited by the heterogeneity of deformation of cells in different locations and by the high degree of anisotropy at a particular location. We have therefore developed a system to impose cyclic, large-strain, homogeneous stretch on a multiwell surface-treated silicone elastomer substrate plated with pulmonary epithelial cells. The pneumatically driven mechanism consists of four plates each with a clamp to fix one edge of the cruciform elastomer substrate. Four linear bearings set at predetermined angles between the plates ensure a constant ratio of principal strains throughout the stretch cycle. We present the design of the device and membrane shape, the surface modifications of the membrane to promote cell adhesion, predicted and experimental measurements of the strain field, and new data using cultured airway epithelial cells. We present for the first time the relationship between the magnitude of cyclic mechanical strain and the extent of wound closure and cell spreading.

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Constitutive soxR Mutations Contribute to Multiple-Antibiotic Resistance in Clinical Escherichia coli Isolates

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.49.7.2746-2752.2005 ◽

2005 ◽

Vol 49 (7) ◽

pp. 2746-2752 ◽

Cited By ~ 63

Author(s):

Anastasia Koutsolioutsou ◽

Samuel Peña-Llopis ◽

Bruce Demple

Keyword(s):

Nitric Oxide ◽

Escherichia Coli ◽

Antibiotic Resistance ◽

Dna Sequences ◽

Single Point ◽

Constitutive Expression ◽

Clinical Isolates ◽

Multiple Antibiotic Resistance ◽

E Coli ◽

First Time

ABSTRACT The soxRS regulon of Escherichia coli and Salmonella enterica is induced by redox-cycling compounds or nitric oxide and provides resistance to superoxide-generating agents, macrophage-generated nitric oxide, antibiotics, and organic solvents. We have previously shown that constitutive expression of soxRS can contribute to quinolone resistance in clinically relevant S. enterica. In this work, we have carried out an analysis of the mechanism of constitutive soxS expression and its role in antibiotic resistance in E. coli clinical isolates. We show that constitutive soxS expression in three out of six strains was caused by single point mutations in the soxR gene. The mutant SoxR proteins contributed to the multiple-antibiotic resistance phenotypes of the clinical strains and were sufficient to confer multiple-antibiotic resistance in a fresh genetic background. In the other three clinical isolates, we observed, for the first time, that elevated soxS expression was not due to mutations in soxR. The mechanism of such increased soxS expression remains unclear. The same E. coli clinical isolates harbored polymorphic soxR and soxS DNA sequences, also seen for the first time.

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New and little known species of Azotus Howard, Ablerus Howard and Physcus Howard (Hym., Aphelinidae) from Africa and Mauritius

Bulletin of Entomological Research ◽

10.1017/s0007485300040761 ◽

1970 ◽

Vol 60 (2) ◽

pp. 237-251 ◽

Cited By ~ 8

Author(s):

D. P. Annecke ◽

H. Patricia Insley

Keyword(s):

New Species ◽

Eastern Cape Province ◽

Related Genus ◽

Eastern Cape ◽

East African ◽

African Species ◽

Ethiopian Region ◽

Genus One ◽

First Time ◽

A New Species

Descriptions are given of five new species of Azotus Howard from the Ethiopian region, including one from Mauritius. These bring the total number of Azotus species known from this region to eight. Two described species, A. capensis Howard and A. elegantulus Silvestri, are annotated and figured, and a key to the species is given. The related genus, Ablerus Howard, is recorded from Africa for the first time on the basis of a new species from the eastern Cape Province, and a new East African species of Physcus Howard, is described. A second East African species of the latter genus, one with flightless females, is characterised but not named to species.

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Regulation of P-Fimbrial Phase Variation Frequencies in Escherichia coli CFT073

Infection and Immunity ◽

10.1128/iai.01989-06 ◽

2007 ◽

Vol 75 (7) ◽

pp. 3325-3334 ◽

Cited By ~ 30

Author(s):

Nicola Holden ◽

Makrina Totsika ◽

Lynn Dixon ◽

Kirsteen Catherwood ◽

David L. Gally

Keyword(s):

Escherichia Coli ◽

Phase Transition ◽

Regulatory Region ◽

Phase Variation ◽

Culture Conditions ◽

Host Tissue ◽

Clinical Isolates ◽

E Coli ◽

K 12 ◽

First Time

ABSTRACT Adherence of uropathogenic Escherichia coli to host tissue is required for infection and is mediated by fimbriae, such as pyelonephritis-associated pili (Pap). Expression of P fimbriae is regulated by phase variation, and to date, phase transition frequencies have been measured only for pap regulatory region constructs integrated into the E. coli K-12 chromosome. The aim of this work was to measure P phase transition frequencies in clinical isolates for the first time, including frequencies for the sequenced strain E. coli CFT073. P fimbriation and associated phase transition frequencies were measured for two E. coli clinical isolates and compared with levels for homologous pap constructs in E. coli K-12. Fimbriation and off-to-on transition frequencies were always higher in the clinical isolate. It was concluded that the regulatory inputs controlling papI expression are likely to be different in E. coli CFT073 and E. coli K-12 as (i) phase variation could be stimulated in E. coli K-12 by induction of papI and (ii) the level of expression of a papI::gfp + fusion was higher in E. coli CFT073 than in E. coli K-12. Furthermore, phase transition frequencies for the two E. coli CFT073 pap clusters were shown to be different depending on the culture conditions, indicating that there is a hierarchy of expression depending on signal inputs.

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Genome-Wide Expression Profile Analysis Reveals Coordinately Regulated Genes Associated with Stepwise Acquisition of Azole Resistance in Candida albicans Clinical Isolates

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.47.4.1220-1227.2003 ◽

2003 ◽

Vol 47 (4) ◽

pp. 1220-1227 ◽

Cited By ~ 112

Author(s):

P. David Rogers ◽

Katherine S. Barker

Keyword(s):

Candida Albicans ◽

Expression Profile ◽

Profile Analysis ◽

Clinical Isolates ◽

Azole Resistance ◽

Down Regulation ◽

Human Fungal Pathogen ◽

Expression Profile Analysis ◽

Genome Wide ◽

First Time

ABSTRACT Candida albicans is an opportunistic human fungal pathogen and a causative agent of oropharyngeal candidiasis (OPC), the most frequent opportunistic infection among patients with AIDS. Fluconazole and other azole antifungal agents have proven effective in the management of OPC; however, with increased use of these agents treatment failures have occurred. Such failures have been associated with the emergence of azole-resistant strains of C. albicans. In the present study we examined changes in the genome-wide gene expression profile of a series of C. albicans clinical isolates representing the stepwise acquisition of azole resistance. In addition to genes previously associated with azole resistance, we identified many genes whose differential expression was for the first time associated with this phenotype. Furthermore, the expression of these genes was correlated with that of the known resistance genes CDR1, CDR2, and CaMDR1. Genes coordinately regulated with the up-regulation of CDR1 and CDR2 included the up-regulation of GPX1 and RTA3 and the down-regulation of EBP1. Genes coordinately regulated with the up-regulation of CaMDR1 included the up-regulation of IFD1, IFD4, IFD5, IFD7, GRP2, DPP1, CRD2, and INO1 and the down-regulation of FET34, OPI3, and IPF1222. Several of these appeared to be coordinately regulated with both the CDR genes and CaMDR1. Many of these genes are involved in the oxidative stress response, suggesting that reduced susceptibility to oxidative damage may contribute to azole resistance. Further evaluation of the role these genes and their respective gene products play in azole antifungal resistance is warranted.

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Identification of Species of Nontuberculous Mycobacteria Clinical Isolates from 8 Provinces of China

BioMed Research International ◽

10.1155/2016/2153910 ◽

2016 ◽

Vol 2016 ◽

pp. 1-10 ◽

Cited By ~ 7

Author(s):

Haican Liu ◽

Lulu Lian ◽

Yi Jiang ◽

Mingxiang Huang ◽

Yunhong Tan ◽

...

Keyword(s):

Nontuberculous Mycobacteria ◽

Scientific Data ◽

Clinical Isolates ◽

Pulmonary Diseases ◽

Pulmonary Infections ◽

Internal Transcribed Spacer Region ◽

Identification Methods ◽

Identification Of Species ◽

First Time ◽

Prevalent Species

Pulmonary diseases caused by nontuberculousmycobacteria(NTM) are increasing in incidence and prevalence worldwide. In this study, we identified NTM species of the clinical isolates from 8 provinces in China, in order to preliminarily provide some basic scientific data in the different species and distribution of NTM related to pulmonary disease in China. A total of 523 clinical isolates from patients with tuberculosis (TB) diagnosed clinically from 2005 to 2012 were identified to the species using conventional and molecular methods, including multilocus PCR,rpoBandhsp65PCR-PRA,hsp65,rpoB, and16S-23Sinternal transcribed spacer region sequencing. The isolates were identified into 3 bacterium genera, including NTM,Gordonia bronchialis,andNocardia farcinica, and, for the 488 NTM isolates, 27 species were identified. For all the 27 species of NTM which were found to cause pulmonary infections in humans, the most prevalent species wasM. intracellulare, followed byM. aviumandM. abscessus. And seven other species were for the first time identified in patients with TB in China. NTM species identification is very important for distinguishing between tuberculosis and NTM pulmonary diseases, and the species diversity drives the creation of diverse and integrated identification methods with higher accuracy and efficacy.

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Antileishmanial Effect of 3-Aminooxy-1-Aminopropane Is Due to Polyamine Depletion

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01055-06 ◽

2006 ◽

Vol 51 (2) ◽

pp. 528-534 ◽

Cited By ~ 26

Author(s):

Sushma Singh ◽

Angana Mukherjee ◽

Alex R. Khomutov ◽

Lo Persson ◽

Olle Heby ◽

...

Keyword(s):

Biosynthetic Pathway ◽

Leishmania Donovani ◽

Clinical Isolates ◽

Growth And Survival ◽

Antiproliferative Effects ◽

Cell Growth And Differentiation ◽

First Time ◽

Rate Limiting ◽

Sodium Antimony Gluconate

ABSTRACT The polyamines putrescine, spermidine, and spermine are organic cations that are required for cell growth and differentiation. Ornithine decarboxylase (ODC), the first and rate-limiting enzyme in the polyamine biosynthetic pathway, catalyzes the conversion of ornithine to putrescine. As the polyamine biosynthetic pathway is essential for the growth and survival of Leishmania donovani, the causative agent of visceral leishmaniasis, inhibition of the pathway is an important leishmaniacidal strategy. In the present study, we examined for the first time the effects of 3-aminooxy-1-aminopropane (APA), an ODC inhibitor, on the growth of L. donovani. APA inhibited the growth of both promastigotes in vitro and amastigotes in the macrophage model, with the 50% inhibitory concentrations being 42 and 5 μM, respectively. However, concentrations of APA up to 200 μM did not affect the viability of macrophages. The effects of APA were completely abolished by the addition of putrescine or spermidine. APA induced a significant decrease in ODC activity and putrescine, spermidine, and trypanothione levels in L. donovani promastigotes. Parasites were transfected with an episomal ODC construct, and these ODC overexpressers exhibited significant resistance to APA and were concomitantly resistant to sodium antimony gluconate (Pentostam), indicating a role for ODC overexpression in antimonial drug resistance. Clinical isolates with sodium antimony gluconate resistance were also found to overexpress ODC and to have significant increases in putrescine and spermidine levels. However, no increase in trypanothione levels was observed. The ODC overexpression in these clinical isolates alleviated the antiproliferative effects of APA. Collectively, our results demonstrate that APA is a potent inhibitor of L. donovani growth and that its leishmaniacidal effect is due to inhibition of ODC.

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A Direct Comparison of Glassy Carbon and PEDOT-PSS Electrodes for High Charge Injection and Low Impedance Neural Interfaces

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.102.68 ◽

2016 ◽

Vol 102 ◽

pp. 68-76 ◽

Cited By ~ 2

Author(s):

Maria Vomero ◽

Elisa Castagnola ◽

Emma Maggiolini ◽

Francesca Ciarpella ◽

Irene Rembado ◽

...

Keyword(s):

Electrochemical Performance ◽

Glassy Carbon ◽

Cultured Cells ◽

Electrochemical Impedance ◽

Neural Interfaces ◽

Somatosensory Stimulation ◽

Brain Surface ◽

First Time

For neural applications, materials able to interface with the brain without harming it while recording high-fidelity signals over long-term implants are still sought after. Glassy Carbon (GC) and Poly (3,4-ethylenedioxythiophene)-poly (styrenesulfonate) (PEDOT-PSS) have proved to be promising materials for neural interfaces as they show – compared to conventional metal electrodes - higher conductivity, better electrochemical stability, very good mechanical properties and therefore seem to be very promising for in vivo applications. We present here, for the first time, a direct comparison between GC and PEDOT-PSS microelectrodes in terms of biocompatibility, electrical and electrochemical properties as well as in vivo recording capabilities, using electrocorticography microelectrode arrays located on flexible polyimide substrate. The GC microelectrodes were fabricated using a traditional negative lithography processes followed by pyrolysis. PEDOT-PSS was selectively electrodeposited on the desired electrodes. Electrochemical performance of the two materials was evaluated through electrochemical impedance spectroscopy and cyclic voltammetry. Biocompatibility was assessed through in-vitro studies evaluating cultured cells viability. The in vivo performance of the GC and PEDOT-PSS electrodes was directly compared by simultaneously recording neuronal activity during somatosensory stimulation in Long-Evans rats. We found that both GC and PEDOT-PSS electrodes outperform metals in terms of electrochemical performance and allow to obtain excellent recordings of somatosensory evoked potentials from the rat brain surface. Furthermore, we found that both GC and PEDOT-PSS substrates are highly biocompatible, confirming that they are safe for neural interface applications.

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BCL2/BCL-XL inhibition induces apoptosis, disrupts cellular calcium homeostasis, and prevents platelet activation

Blood ◽

10.1182/blood-2011-03-344812 ◽

2011 ◽

Vol 117 (26) ◽

pp. 7145-7154 ◽

Cited By ~ 112

Author(s):

Meike Vogler ◽

Hassan A. Hamali ◽

Xiao-Ming Sun ◽

Edward T. W. Bampton ◽

David Dinsdale ◽

...

Keyword(s):

Platelet Activation ◽

Specific Inhibitor ◽

Leukemia Cells ◽

Calcium Stores ◽

Selective Toxicity ◽

Reticulated Platelets ◽

Apoptotic Pathways ◽

Induced Apoptosis ◽

First Time

Abstract Apoptosis in megakaryocytes results in the formation of platelets. The role of apoptotic pathways in platelet turnover and in the apoptotic-like changes seen after platelet activation is poorly understood. ABT-263 (Navitoclax), a specific inhibitor of antiapoptotic BCL2 proteins, which is currently being evaluated in clinical trials for the treatment of leukemia and other malignancies, induces a dose-limiting thrombocytopenia. In this study, the relationship between BCL2/BCL-XL inhibition, apoptosis, and platelet activation was investigated. Exposure to ABT-263 induced apoptosis but repressed platelet activation by physiologic agonists. Notably, ABT-263 induced an immediate calcium response in platelets and the depletion of intracellular calcium stores, indicating that on BCL2/BCL-XL inhibition platelet activation is abrogated because of a diminished calcium signaling. By comparing the effects of ABT-263 and its analog ABT-737 on platelets and leukemia cells from the same donor, we show, for the first time, that these BCL2/BCL-XL inhibitors do not offer any selective toxicity but induce apoptosis at similar concentrations in leukemia cells and platelets. However, reticulated platelets are less sensitive to apoptosis, supporting the hypothesis that treatment with ABT-263 induces a selective loss of older platelets and providing an explanation for the transient thrombocytopenia observed on ABT-263 treatment.

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