Kinetic investigation of the hydrolysis of aminoacyl p-nitroanilides by dipeptidyl peptidase IV from human and pig kidney

Dipeptidyl peptidase IV (dipeptidyl-peptide hydrolase, EC 3.4.14.5), an enzyme that participates in the catabolism of bradykinin and Substance P as well as the post-translational processing of various other peptides, has been purified from human and pig kidney. The assay reaction involved the cleavage of p-nitroaniline (pNA) from various dipeptidyl p-nitroanilides. The specific activities of the human and pig enzyme (with Gly-Pro-pNA at pH 7.6) were 49.2 and 45.8, respectively. The dependence of initial reaction velocity on substrate concentration was determined for a variety of dipeptidyl p-nitroanilides over the concentration range 0.05 to 2.0 mM. Most of the substrates tested produced significant non-hyperbolic behavior for the function v vs. S at concentrations above 0.5 mM. As to differences between the two enzymes, the pig enzyme exhibited featureless (i.e., hyperbolic) behavior with Glu-Pro-pNA concentrations as high as 2.0 mM, whereas the human enzyme produced significant non-hyperbolic behavior for the function v vs. S, beginning at S = 0.4 mM. Thus, the human and pig dipeptidyl peptidases IV are kinetically distinct enzyme forms.     

Invasion theory and biological control

Recent advances in the mathematical theory of invasion dynamics have much to offer to biological control. Here we synthesize several results concerning the spatiotemporal dynamics that occur when a biocontrol agent spreads into a population of an invading pest species. We outline conditions under which specialist and generalist predators can influence the density and rate of spatial spread of the pest, including the rather stringent conditions under which a specialist predator can successfully reverse a pest invasion. We next discuss the connections between long distance dispersal and invasive spread, emphasizing the different consequences of fast spreading pests and predators. Recent theory has considered the effects of population stage-structure on invasion dynamics, and we discuss how population demography affects the biological control of invading pests. Because low population densities generally characterize early stages of an invasion, we discuss the lessons invasion theory teaches concerning the detectability of invasions. Stochasticity and density-dependent dynamics are common features of many real invasions, influencing both the spatial character (e.g. patchiness) of pest invasions and the success of biocontrol agents. We conclude by outlining theoretical results delineating how stochastic effects and complex dynamics generated by density dependence can facilitate or impede biological pest control.     

Human health risks of metals and metalloids in muscle tissue of Synodontis zambezensis Peters, 1852 from Flag Boshielo Dam,South Africa

Muscle tissue from 63 Synodontis zambezensis collected bimonthly in 2013 at Flag Boshielo Dam were analysed for metals and metalloids in a desktop human health risk assessment. The Hazard Quotient, based on a weekly meal of 67 g of fish muscle, exceeded the maximum acceptable level of one for lead, cobalt, cadmium, mercury, arsenic and selenium. The concentrations of these elements were higher in 2013 than those recorded in 2009 and 2012 in other fish species from Flag Boshielo Dam and these may pose a long-term health risk if consumed regularly by impoverished rural communities reliant on fish as a source of protein.     

Proteasome inhibition drastically but reversibly impairs murine lymphocyte development

The proteasome inhibitor bortezomib, which induces cell death in various cancer cell lines including lymphatic neoplasias, has recently been approved for the treatment of relapsed multiple myeloma. Important mechanisms of proteasome inhibitor-mediated tumor cell death are the inhibition of NF-kappaB activation and induction of the terminal unfolded protein response (UPR). However, little is known about effects of bortezomib on developing and mature lymphocytes. Therefore, Balb/C mice were injected with bortezomib and lymphocyte subsets were analyzed. This treatment resulted in dramatically decreased numbers of T and B lymphocyte precursors, while mature lymphocytes were only partially affected. Thymocytes were almost depleted 3 days after a single bortezomib injection, pro-B and pre-B cells already after 2 days. Thymocytes and B cell precursors recovered within 2 weeks. The decreased numbers of developing lymphocytes were due to apoptotic cell death accompanied by strongly increased caspase 3/7 activity. Within 8 h after bortezomib injection, there was a strong induction of heat shock protein 70 and C/EBP homologous protein in bone marrow B cells, indicating endoplasmic reticulum stress and activation of the terminal UPR, respectively. Hence, induction of apoptosis by proteasome inhibition can dramatically affect lymphocyte development, a fact which has important implications for the clinical use of bortezomib, especially in situations with ongoing lymphopoiesis.     

ABRF-PRG05: De Novo Peptide Sequence Determination

A common request of proteomics core facilities is protein identification. However, in some instances primary sequence information for the protein in question is not present in public databases. In other cases, the amino acid sequence of a protein may differ in some way from the sequence predicted from the gene sequence in a database as a result of gene mutation, gene splicing, and/or multiple posttranslational modifications. Thus, it may be necessary to determine the sequence of one or more peptides de novo in order to identify and/or adequately characterize the protein of interest. The primary goal of this study was to give participating laboratories an opportunity to evaluate their proficiency in sequencing unknown peptides that are not included in any published database. Samples containing 3–6 pmol each of five synthetic peptides with amino acid sequences that were not present in public databases were sent to 106 laboratories. One nonstandard amino acid was present in one of the peptides. From a comparison of the results obtained by different strategies, participating laboratories will be able to gauge their own capabilities and establish realistic expectations for the approaches that can be used for this determination.     

Visualisation tool for peptide fractionation data in proteomics: application to OFFGEL isoelectric focussing

Background  

OFFGEL isoelectric focussing (IEF) has become a popular tool in proteomics to fractionate peptides or proteins. As a consequence there is a need for software solutions supporting data mining, interpretation and characterisation of experimental quality.     

Gauging U.S. Emergency Medical Services Workers' Willingness to Respond to Pandemic Influenza Using a Threat- and Efficacy-Based Assessment Framework

Background

Emergency Medical Services workers'' willingness to report to duty in an influenza pandemic is essential to healthcare system surge amidst a global threat. Application of Witte''s Extended Parallel Process Model (EPPM) has shown utility for revealing influences of perceived threat and efficacy on non-EMS public health providers'' willingness to respond in an influenza pandemic. We thus propose using an EPPM-informed assessment of EMS workers'' perspectives toward fulfilling their influenza pandemic response roles.

Methodology/Principal Findings

We administered an EPPM-informed snapshot survey about attitudes and beliefs toward pandemic influenza response, to a nationally representative, stratified random sample of 1,537 U.S. EMS workers from May–June 2009 (overall response rate: 49%). Of the 586 respondents who met inclusion criteria (currently active EMS providers in primarily EMS response roles), 12% indicated they would not voluntarily report to duty in a pandemic influenza emergency if asked, 7% if required. A majority (52%) indicated their unwillingness to report to work if risk of disease transmission to family existed. Confidence in personal safety at work (OR = 3.3) and a high threat/high efficacy (“concerned and confident”) EPPM profile (OR = 4.7) distinguished those who were more likely to voluntarily report to duty. Although 96% of EMS workers indicated that they would probably or definitely report to work if they were guaranteed a pandemic influenza vaccine, only 59% had received an influenza immunization in the preceding 12 months.

Conclusions/Significance

EMS workers'' response willingness gaps pose a substantial challenge to prehospital surge capacity in an influenza pandemic. “Concerned and confident” EMS workers are more than four times as likely to fulfill pandemic influenza response expectations. Confidence in workplace safety is a positively influential modifier of their response willingness. These findings can inform insights into interventions for enhancing EMS workers'' willingness to respond in the face of a global infectious disease threat.