Expression and copper binding characteristics of Plasmodium falciparum cytochrome c oxidase assembly factor 11, Cox11.

BACKGROUND: Copper is an essential metal for living organisms as a catalytic co-factor for important enzymes, like cytochrome c oxidase the final enzyme in the electron transport chain. Plasmodium falciparum parasites in infected red blood cells are killed by excess copper and development in erythrocytes is inhibited by copper chelators. Cytochrome c oxidase in yeast obtains copper for the CuB site in the Cox1 subunit from Cox11. METHODS: A 162 amino acid carboxy-terminal domain of the P. falciparum Cox11 ortholog (PfCox11Ct) was recombinantly expressed and the rMBPPfCox11Ct affinity purified. Copper binding was measured in vitro and in Escherichia coli host cells. Site directed mutagenesis was used to identify key copper binding cysteines. Antibodies confirmed the expression of the native protein. RESULTS: rMBPPfCox11Ct was expressed as a 62 kDa protein fused with the maltose binding protein and affinity purified. rMBPPfCox11Ct bound copper measured by: a bicinchoninic acid release assay; atomic absorption spectroscopy; a bacterial host growth inhibition assay; ascorbate oxidation inhibition and in a thermal shift assay. The cysteine 157 amino acid was shown to be important for in vitro copper binding by PfCox11whilst Cys 60 was not. The native protein was detected by antibodies against rMBPPfCox11Ct. CONCLUSIONS: Plasmodium spp. express the PfCox11 protein which shares structural features and copper binding motifs with Cox11 from other species. PfCox11 binds copper and is, therefore, predicted to transfer copper to the CuB site of Plasmodium cytochrome c oxidase. Characterization of Plasmodium spp. proteins involved in copper metabolism will help sceintists understand the role of cytochrome c oxidase and this essential metal in Plasmodium homeostasis.

Expression and copper binding properties of the N-terminal domain of copper P-type ATPases of African trypanosomes.

Copper is an essential component of cuproproteins but can be toxic to cells, therefore copper metabolism is very carefully regulated within cells. To gain insight into trypanosome copper metabolism, Trypanosoma spp. genomic databases were screened for the presence of copper-containing and -transporting proteins. Among other genes encoding copper-binding proteins, a copper-transporting P-type ATPase (CuATPase) gene was identified. Sequence and phylogenetic analyses suggest that the gene codes for a Cu+ transporter belonging to the P1B-1 ATPase subfamily that has an N-terminal domain with copper binding motifs. The N-terminal cytosolic domains of the proteins from Trypanosoma congolense and Trypanosoma brucei brucei were recombinantly expressed in Escherichia coli as maltose binding protein (MBP) fusion proteins. These N-terminal domains bound copper in vitro and within E. coli cells, more than the control MBP fusion partner alone. The copper binding properties of the recombinant proteins were further confirmed when they inhibited copper catalysed ascorbate oxidation. Native CuATPases were detected in a western blot of lysates of T. congolense IL3000 and T. b. brucei ILTat1.1 bloodstream form parasites using affinity purified IgY antibodies against N-terminal domain peptides. The CuATPase was also detected by immunofluorescence in T. b. brucei bloodstream form parasites where it was associated with subcellular vesicles. In conclusion, Trypanosoma species express a copper-transporting P1B-1-type ATPase and together with other copper-binding proteins identified in the genomes of kinetoplastid parasites may constitute potential targets for anti-trypanosomal drug discovery.

Improving diagnostic performance of 18F-FDG-PET/CT for assessment of regional nodal involvement in non-small cell lung cancer.

AIM: To assess the diagnostic performance of combined 2-[18F]-fluoro-2-deoxy-d-glucose (18F-FDG) positron-emission tomography (PET)/computed tomography (CT) mediastinal blood pool (MBP) activity cut-off for staging nodal involvement, and to examine other variables that may improve the diagnostic performance of PET/CT in non-small cell lung cancer (NSCLC). MATERIALS AND METHODS: All patients diagnosed with NSCLC who underwent endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) and 18F-FDG-PET/CT between June 2016 and August 2018 were included. Nodal station and nodal staging-based analyses were performed, comparing the MBP cut-off and five other PET/CT parameters (node maximum standardised uptake value [SUVmax], node/MBP SUVmax ratio, node/tumour SUVmax ratio, node short axis diameter, and node SUVmax/node short axis diameter ratio) with histopathology results. The optimal cut-off value for each PET/CT parameter was determined using receiver operating characteristic curve analysis. RESULTS: One hundred and thirteen patients with a total of 321 nodes with pathological sampling were included. Nodal activity above MBP on PET/CT demonstrated 97.4% sensitivity, 35.8% specificity, 32.8% positive predictive value, and 97.8% negative predictive value. Of the five other PET/CT parameters examined, the two most promising were node SUVmax and node/MBP SUVmax. The node SUVmax cut-off of 3.9 demonstrated 90.9% sensitivity and 61.9% specificity, and the node/MBP SUVmax cut-off of 1.7 demonstrated 90.9% sensitivity and 60.7% specificity. CONCLUSION: Compared to the MBP cut-off, use of a higher node/MBP SUVmax ratio cut-off and use of other PET/CT variables can improve the diagnostic performance of PET/CT for NSCLC nodal staging. In particular, specificity for detecting malignant nodal involvement is improved while maintaining high sensitivity.

Concentrating Proteins by Salt, Polyethylene Glycol, Solvent, SDS Precipitation, Three-Phase Partitioning, Dialysis, Centrifugation, Ultrafiltration, Lyophilization, Affinity Chromatography, Immunoprecipitation or Increased Temperature for Protein Isolation, Drug Interaction, and Proteomic and Peptidomic Evaluation.

In protein isolation, drug interaction studies, and proteomic or peptidomic procedures, protein solutions are often concentrated to remove solvents and undesirable molecules, to separate protein fractions, or to increase protein concentrations. Proteins can be concentrated by precipitation from solution with ammonium sulfate, polyethylene glycol, organic solvents, trichloroacetic acid, potassium chloride/sodium dodecyl sulfate thermal denaturation, and three-phase partitioning. Solvents can be removed by passage through a semipermeable barrier where protein solutions are forced against the barrier in a centrifuge tube or with increased pressure, concentrating proteins in the remaining solution. The semipermeable barrier can be surrounded by a hygroscopic reagent to draw the solvent across the membrane. Proteins can be concentrated by freeze-drying (lyophilization). Unique ligand interactions with proteins can be used to select for proteins by affinity purification or immunoprecipitation. All these methods to concentrate proteins are discussed.

Phosphoethanolamine-N-methyltransferase is a potential biomarker for the diagnosis of P. knowlesi and P. falciparum malaria.

BACKGROUND: Plasmodium knowlesi is recognised as the main cause of human malaria in Southeast Asia. The disease is often misdiagnosed as P. falciparum or P. malariae infections by microscopy, and the disease is difficult to eliminate due to its presence in both humans and monkeys. P. knowlesi infections can rapidly cause severe disease and require prompt diagnosis and treatment. No protein biomarker exists for the rapid diagnostic test (RDT) detection of P. knowlesi infections. Plasmodium knowlesi infections can be diagnosed by PCR. METHODS AND PRINCIPAL FINDINGS: Phosphoethanolamine-N-methyltransferase (PMT) is involved in malaria lipid biosynthesis and is not found in the human host. The P. falciparum, P. vivax and P. knowlesi PMT proteins were recombinantly expressed in BL21(DE3) Escherichia coli host cells, affinity purified and used to raise antibodies in chickens. Antibodies against each recombinant PMT protein all detected all three recombinant proteins and the native 29 kDa P. falciparum PMT protein on western blots and in ELISA. Antibodies against a PMT epitope (PLENNQYTDEGVKC) common to all three PMT orthologues detected all three proteins. Antibodies against unique peptides from each orthologue of PMT, PfCEVEHKYLHENKE, PvVYSIKEYNSLKDC, PkLYPTDEYNSLKDC detected only the parent protein in western blots and P. falciparum infected red blood cell lysates or blood lysates spiked with the respective proteins. Similar concentrations of PfPMT and the control, PfLDH, were detected in the same parasite lysate. The recombinant PfPMT protein was detected by a human anti-malaria antibody pool. CONCLUSION: PMT, like the pan-specific LDH biomarker used in RDT tests, is both soluble, present at comparable concentrations in the parasite and constitutes a promising antimalarial drug target. PMT is absent from the human proteome. PMT has the potential as a biomarker for human malaria and in particular as the first P. knowlesi specific protein with diagnostic potential for the identification of a P. knowlesi infection.

Summary of the British Thoracic Society guidelines for advanced diagnostic and therapeutic flexible bronchoscopy in adults.

This new guideline covers the rapidly advancing field of interventional bronchoscopy using flexible bronchoscopy. It includes the use of more complex diagnostic procedures such as endobronchial ultrasound, interventions for the relief of central airway obstruction due to malignancy and the recent development of endobronchial therapies for chronic obstructive pulmonary disease and asthma. The guideline aims to help all those who undertake flexible bronchoscopy to understand more about this important area. It also aims to inform respiratory physicians and other specialists dealing with lung cancer of the procedures possible in the management and palliation of central airway obstruction. The guideline covers transbronchial needle aspiration and endobronchial ultrasound-guided transbronchial needle aspiration, electrocautery/diathermy, argon plasma coagulation and thermal laser, cryotherapy, cryoextraction, photodynamic therapy, brachytherapy, tracheobronchial stenting, electromagnetic navigation bronchoscopy, endobronchial valves for emphysema and bronchial thermoplasty for asthma.

Anti-peptide antibodies differentiate between plasmodial lactate dehydrogenases.

Malaria lactate dehydrogenase, a glycolytic enzyme, is a malaria diagnostic target in lateral flow immunochromatographic rapid diagnostic tests. Recombinant Plasmodium yoelii LDH was cloned into the pET-28a vector, expressed and the expressed protein purified from a Ni-NTA affinity matrix. A pan-malarial LDH antibody directed against a common malaria LDH peptide (APGKSDKEWNRDDLL) and two anti-peptide antibodies, each targeting a unique Plasmodium falciparum (LISDAELEAIFDC) and Plasmodium vivax (KITDEEVEGIFDC) LDH peptide were raised in chickens. The antibodies were affinity purified with the appropriate peptide affinity matrix. The affinity purified anti-peptide antibodies detected recombinant P. falciparum, P. vivax and P. yoelii LDH and native P. falciparum and P. yoelii LDH in western blots and immunofluorescence studies. The pan-malarial antibody detected LDH from the three malaria species in western blots. The species-specific anti-peptide antibodies differentiated between P. falciparum and P. vivax LDH. Affinity purified chicken antibodies against recombinant PfLDH, PvLDH and PyLDH proteins each detected the parent and orthologous proteins with similar titers in an ELISA. The study supports an anti-peptide antibody approach to the development of diagnostic reagents.

Managing acute on chronic respiratory failure: a guide to non-invasive ventilation.

Acute-on-chronic respiratory failure is becoming an increasingly common medical emergency, mostly as a result of exacerbations of chronic obstructive pulmonary disease. It is associated with high mortality rates and so practising the best evidence-based management is vital.

PfPK7, an atypical MEK-related protein kinase, reflects the absence of classical three-component MAPK pathways in the human malaria parasite Plasmodium falciparum.

Two members of the mitogen-activated protein kinase (MAPK) family have been previously characterized in Plasmodium falciparum, but in vitro attempts at identifying MAP kinase kinase (MAPKK) homologues have failed. Here we report the characterization of a novel plasmodial protein kinase, PfPK7, whose top scores in blastp analysis belong to the MAPKK3/6 subgroup of MAPKKs. However, homology to MAPKKs is restricted to regions of the C-terminal lobe of the kinase domain, whereas the N-terminal region is closer to fungal protein kinase A enzymes (PKA, members of the AGC group of protein kinases). Hence, PfPK7 is a 'composite' enzyme displaying regions of similarity to more than one protein kinase family, similar to a few other plasmodial protein kinases. PfPK7 is expressed in several developmental stages of the parasite, both in the mosquito vector and in the human host. Recombinant PfPK7 displayed kinase activity towards a variety of substrates, but was unable to phosphorylate the two P. falciparum MAPK homologues in vitro, and was insensitive to PKA and MEK inhibitors. Together with the absence of a typical MAPKK activation site in its T-loop, this suggests that PfPK7 is not a MAPKK orthologue, despite the fact that this enzyme is the most 'MAPKK-like' enzyme encoded in the P. falciparum genome. This is consistent with recent observations that the plasmodial MAPKs are not true orthologues of the ERK1/2, p38 or JNK MAPKs, and strengthens the evidence that classical three-component module-dependent MAPK signalling pathways do not operate in malaria parasites, a feature that has not been described in any other eukaryote.

Clinical results of the CLARION magnetless cochlear implant.

This paper reports initial results for the CLARION Multi-Strategy Cochlear Implant, presently under investigational study in Europe. A magnetless implantable cochlear stimulator (ICS) with an ear-mold-supported headpiece was designed in response to an increasing demand for a magnetic resonance imaging (MRI)-compatible cochlear implant. Surgical technique, accompanying magnetless headpiece, and MRI compatibility were evaluated in 11 deaf patients (ages 6 to 62 years) who were implanted with a magnetless Clarion implant. Because of the headset mechanics, the ICS was implanted closer behind the ear than a magnet-containing ICS. The ICS-MRI compatibility was investigated with 1.5- and 0.3-T MRI. Results showed that the surgery was relatively safe and easy to learn. The headset was stable and reliable. The MRI compatibility tests indicate that the ICS poses no contraindication for patients needing MRI. Overall, the results suggest that the Clarion magnetless cochlear implant is relatively safe and easy to implant, is MRI-compatible, and functions well with the ear-mold-supported headpiece.

The influence of ionizing radiation on the CLARION 1.2 cochlear implant during radiation therapy.

OBJECTIVE: This study aimed to determine the maximum dose of radiation the CLARION 1.2 cochlear implant can withstand safely. INTRODUCTION: Cochlear implants restore functional hearing to patients with sensorineural deafness. Because some patients may need radiation therapy, it is important to investigate the influence of ionizing radiation on cochlear implant function. METHODS: This study tested the function of four CLARION 1.2 implants (Advanced Bionics, Sylmar, CA, U.S.A.) after varying radiation treatments with gamma rays. The first implant received a cumulative dosage of 69 Gy over nine treatments (single doses between 0.1-30 Gy). The second was irradiated with a total of 90 Gy, receiving three treatments of 30 Gy each. The third and fourth received doses more typical of patient therapy (i.e., 2 Gy) approximately 30 times, for a cumulative dosage of approximately 60 Gy. Implant function was tested after every treatment; the CLARION implant incorporates a back-telemetry system, allowing impedance and current output testing. RESULTS: Despite the type of treatment, the results were quite consistent: difficulties in function occurred when the cumulative dosage inside the implant was approximately 60 Gy. The first implant recovered completely and the second recovered partially. DISCUSSION: The CLARION 1.2 cochlear implant seems to safely withstand approximately 60 Gy of radiation before experiencing functional difficulties. In a clinical situation, the implant would not likely be in the target volume irradiated, and thus the patient's therapeutic cumulative dosage might be higher.

Intravenous immunoglobulin in the treatment of paediatric cerebral malaria.

Hyperimmune globulin can inhibit and reverse the cytoadherence between Plasmodium falciparum-infected erythrocytes and melanoma cells in vitro. Cytoadherence is believed to mediate disease in cerebral malaria. Therefore we studied the efficacy of i.v. immunoglobulin, purified from the plasma of local semi-immune blood donors, as an adjunct to standard treatment for cerebral malaria in Malawian children. The immunoglobulin preparation (IFAT antimalarial antibody titre 1:5120) recognized erythrocyte-associated antigens of each of 22 Malawian P. falciparum isolates studied, and reversed binding of Malawian isolates to melanoma cells. Immunoglobulin did not reverse binding to human monocytes or to cells of the human histiocytic lymphoma cell line U937. Thirty-one children with P. falciparum parasitaemia and unrousable coma were enrolled. All were treated with i.v. quinine dihydrochloride; in addition patients were randomized to receive either immunoglobulin (400 mg/kg by i.v. infusion over 3 h) or placebo (albumen and sucrose by similar infusion) in a double blind trial with sequential analysis. Of 16 patients receiving immunoglobulin, five (31%) died and five survivors had neurological sequelae. Of 15 patients receiving placebo, one (7%) died and two had sequelae. Parasite clearance, fever clearance and coma resolution times in survivors were similar in the two groups. Although the difference in outcome between the two groups was not significant, the trial was stopped because immunoglobulin was demonstrated not to be superior to placebo.

Plasmodium falciparum: diversity of isolates from Malawi in their cytoadherence to melanoma cells and monocytes in vitro.

We observed considerable diversity in the cytoadherence of Plasmodium falciparum isolates from Malawi to melanoma cells, U937 cells and human peripheral monocytes. Each isolate exhibited a unique cytoadherence profile for the three human cell types. These isolates generally adhered well to U937 cells and fresh monocytes, moderately to melanoma cells and poorly to TE 671, MIA-Pa-Ca, WI 38, PLC/PRF/5 and HeLa cells. An antimalarial immunoglobulin pool inhibited binding to melanoma cells by 50% or more and to U937 cells by 25% or less. There was no correlation between in vitro cytoadherence to the three cells and clinical disease. These results suggest that malarial adherence ligands exposed on the surface of infected erythrocytes vary from one isolate to another.

Variation in the cytoadherence characteristics of malaria parasites: is this a true virulence factor?

The sequestration of Plasmodium falciparum-infected erythrocytes to the endothelial cells of brain capillaries is believed to represent one of the determining factors in the pathogenesis of cerebral malaria. In vitro studies of cytoadherence provide an experimental approach to understand the mechanism of sequestration and the respective roles played by parasite and host components in this interaction. This paper critically reviews current studies on cytoadherence, with particular emphasis on the nature of the information provided by such studies and their limitations. The paper also describes how cytoadherence studies using the patient's own monocytes can provide original information on the level of receptor up-regulation in the course of malarial infection

Evidence that the multifunctional polypeptides of vertebrate and fungal fatty acid synthases have arisen by independent gene fusion events.

The enoyl reductase (NADPH binding site) of rabbit mammary fatty acid synthase has been radioactively labelled using pyridoxal phosphate and sodium [3H]borohydride. Using this method we have been able to add this site to the four sites whose location has already been mapped within the multifunctional polypeptide chain of the protein. The results show that the enoyl reductase lies between the 3-oxoacylsynthase and the acyl carrier. This confirms that the active sites occur in a different order on the single multifunctional polypeptide of vertebrate fatty acid synthase and the two multifunctional polypeptides of fungal fatty acid synthase, and suggests that these two systems have arisen by independent gene fusion events.