Development and evaluation of a monoclonal antibody-based inhibition ELISA for the quantification of chymosin in solution

Chymosin is the major enzyme of natural rennet, traditionally used in cheese making for its high milk-clotting activity. For technical reasons, an accurate characterization of rennet should include its total clotting activity and also its enzymatic composition. Monoclonal antibodies specific to chymosin were obtained from mice immunized with purified bovine chymosin, and an inhibition enzyme-linked immunosorbent assay (ELISA) was developed for the quantification of chymosin in solution. No cross-reactivity was observed with other milk-clotting enzymes commonly used in cheese making. The limit of detection and limit of quantification were 125 and 400 ng/mL, respectively. The values of precision within and among runs were 7.23 and 7.39%, respectively, and satisfying recovery, from 92 to 119%, was found for spiked samples. The inhibition ELISA was successfully applied to commercial rennets, and the results were consistent with those obtained using the standard chromatographic method (IDF 110: A, 1987).

[Life-threatening Panton-Valentine leukocidin-associated staphylococcal infections in children. A broad spectrum of clinical presentations]

Panton-Valentine leukocidin (PVL) is a major toxic virulence factor secreted by community-acquired methicillin-sensitive or methicillin-resistant Staphylococcus aureus (SA). SA-PVL can be responsible for life-threatening infections in healthy children with a wide spectrum of clinical presentations involving lung, skin, and soft tissues or bones and joints. PVL production should always be considered in severe SA infections. The pediatric medicine community remains poorly informed regarding the therapeutic management of this infection, which should be early and aggressive. Intravenous empiric antibiotics against SA and its toxins must be given with early and sometimes iterative surgical procedures to drain abscesses and to stop bacterial proliferation and necrosis in the tissues. Here, we report the cases of three patients admitted for SA-PVL infections to the pediatric intensive care unit. Initial clinical presentation in the three patients was multifocal osteomyelitis associated with necrotizing pneumonia; severe skin infection with septic shock; and non-necrotic pneumonia with pleural and pericardial effusion. Appropriate treatments resulted in a good outcome in all cases. Following these illustrations, we describe a number of practical key points in the optimal medical and surgical management of severe SA-PVL infections, with a review of the literature.

A standardised static in vitro digestion method suitable for food - an international consensus

Simulated gastro-intestinal digestion is widely employed in many fields of food and nutritional sciences, as conducting human trials are often costly, resource intensive, and ethically disputable. As a consequence, in vitro alternatives that determine endpoints such as the bioaccessibility of nutrients and non-nutrients or the digestibility of macronutrients (e.g. lipids, proteins and carbohydrates) are used for screening and building new hypotheses. Various digestion models have been proposed, often impeding the possibility to compare results across research teams. For example, a large variety of enzymes from different sources such as of porcine, rabbit or human origin have been used, differing in their activity and characterization. Differences in pH, mineral type, ionic strength and digestion time, which alter enzyme activity and other phenomena, may also considerably alter results. Other parameters such as the presence of phospholipids, individual enzymes such as gastric lipase and digestive emulsifiers vs. their mixtures (e.g. pancreatin and bile salts), and the ratio of food bolus to digestive fluids, have also been discussed at length. In the present consensus paper, within the COST Infogest network, we propose a general standardised and practical static digestion method based on physiologically relevant conditions that can be applied for various endpoints, which may be amended to accommodate further specific requirements. A frameset of parameters including the oral, gastric and small intestinal digestion are outlined and their relevance discussed in relation to available in vivo data and enzymes. This consensus paper will give a detailed protocol and a line-by-line, guidance, recommendations and justifications but also limitation of the proposed model. This harmonised static, in vitro digestion method for food should aid the production of more comparable data in the future.

Electronic health records: new opportunities for clinical research

Clinical research is on the threshold of a new era in which electronic health records (EHRs) are gaining an important novel supporting role. Whilst EHRs used for routine clinical care have some limitations at present, as discussed in this review, new improved systems and emerging research infrastructures are being developed to ensure that EHRs can be used for secondary purposes such as clinical research, including the design and execution of clinical trials for new medicines. EHR systems should be able to exchange information through the use of recently published international standards for their interoperability and clinically validated information structures (such as archetypes and international health terminologies), to ensure consistent and more complete recording and sharing of data for various patient groups. Such systems will counteract the obstacles of differing clinical languages and styles of documentation as well as the recognized incompleteness of routine records. Here, we discuss some of the legal and ethical concerns of clinical research data reuse and technical security measures that can enable such research while protecting privacy. In the emerging research landscape, cooperation infrastructures are being built where research projects can utilize the availability of patient data from federated EHR systems from many different sites, as well as in international multilingual settings. Amongst several initiatives described, the EHR4CR project offers a promising method for clinical research. One of the first achievements of this project was the development of a protocol feasibility prototype which is used for finding patients eligible for clinical trials from multiple sources.

Spatial and temporal MRI profile of ischemic tissue after the acute stages of a permanent mouse model of stroke

OBJECT

To characterize the progression of injured tissue resulting from a permanent focal cerebral ischemia after the acute phase, Magnetic Resonance Imaging (MRI) monitoring was performed on adult male C57BL/6J mice in the subacute stages, and correlated to histological analyses.

MATERIAL AND METHODS

Lesions were induced by electrocoagulation of the middle cerebral artery. Serial MRI measurements and weighted-images (T2, T1, T2* and Diffusion Tensor Imaging) were performed on a 9.4T scanner. Histological data (Cresyl-Violet staining and laminin-, Iba1- and GFAP-immunostainings) were obtained 1 and 2 weeks after the stroke.

RESULTS

Two days after stroke, tissues assumed to correspond to the infarct core, were detected as a hyperintensity signal area in T2-weighted images. One week later, low-intensity signal areas appeared. Longitudinal MRI study showed that these areas remained present over the following week, and was mainly linked to a drop of the T2 relaxation time value in the corresponding tissues. Correlation with histological data and immuno-histochemistry showed that these areas corresponded to microglial cells.

CONCLUSION

The present data provide, for the first time detailed MRI parameters of microglial cells dynamics, allowing its non-invasive monitoring during the chronic stages of a stroke. This could be particularly interesting in regards to emerging anti-inflammatory stroke therapies.

A Bayesian network approach to the study of historical epidemiological databases: modelling meningitis outbreaks in the Niger

OBJECTIVE

To develop a tool for evaluating the risk that an outbreak of meningitis will occur in a particular district of the Niger after outbreaks have been reported in other, specified districts of the country.

METHODS

A Bayesian network was represented by a graph composed of 38 nodes (one for each district in the Niger) connected by arrows. In the graph, each node directly influenced each of the "child" nodes that lay at the ends of the arrows arising from that node, according to conditional probabilities. The probabilities between "influencing" and "influenced" districts were estimated by analysis of databases that held weekly records of meningitis outbreaks in the Niger between 1986 and 2005. For each week of interest, each district was given a Boolean-variable score of 1 (if meningitis incidence in the district reached an epidemic threshold in that week) or 0.

FINDINGS

The Bayesian network approach provided important and original information, allowing the identification of the districts that influence meningitis risk in other districts (and the districts that are influenced by any particular district) and the evaluation of the level of influence between each pair of districts.

CONCLUSION

Bayesian networks offer a promising approach to understanding the dynamics of epidemics, estimating the risk of outbreaks in particular areas and allowing control interventions to be targeted at high-risk areas.

Assessing the cost-effectiveness of biologic agents for the management of moderate-to-severe rheumatoid arthritis in anti-TNF inadequate responders in Italy: a modelling approach

OBJECTIVES

The objective of this study is to assess cost-effectiveness of different biologic strategies in patients with moderate-to-severe active RA after an insufficient response to anti-TNF agents within the context of the Italian healthcare system.

METHODS

Simulation models were developed allowing for potential biologic therapy switch at each 6-month time point in case of an insufficient response to the previous biologic agent. Biologic treatments included etanercept, abatacept, adalimumab, rituximab or infliximab. Effectiveness criteria for these models were defined as achieving a state of low disease activity (LDAS) [DAS28 ≤3.2] or remission (RS) [DAS28<2.6]. Monte-Carlo simulations were performed for each sequence to manage data variability.

RESULTS

The biologic treatment sequence using abatacept after an insufficient response to a first anti-TNF agent appeared significantly more efficacious over 2 years (102 days in LDAS) compared to rituximab (82 days in LDAS). The sequence using abatacept after 2 anti-TNF agents appeared significantly more efficacious (63 days in LDAS) compared to using a third anti-TNF agent (32 days in LDAS). Mean cost-effectiveness ratios showed significantly lower costs per day in LDAS with abatacept used after one anti-TNF agent (€376) compared to rituximab (€456). The sequence using abatacept after 2 anti-TNF agents was also more cost-effective (€642 per day in LDAS) versus a sequential use of anti-TNF therapies (€1164 per day in LDAS). All comparisons were confirmed when using the remission effectiveness criteria.

CONCLUSIONS

The results of this health economics modelling study suggest that the biologic treatment sequence using abatacept after an insufficient response to a first anti-TNF agent appears significantly more effective and cost-effective versus a similar sequence using rituximab for achieving remission or LDAS. The results also indicate that in the case of an insufficient reponse to 2 anti-TNF agents, abatacept appears more effective and cost-effective than using a 3rd anti-TNF agent.

Use of Total Error concept in the validation of viral activity in cell cultures

Due to the high variability inherent of experimental recipients, validating biological methods is often a complex exercise, and following ICH Q2R1 recommendations is not always feasible and/or meaningful. Linking systematic error and random error to obtain a unique criterion, as defined in ISO guideline, could be of interest to capture the total variability in biological assays. In this paper, the use of Total Error concept in the validation of biological assays was for the first time investigated and compared to a conventional interpretation of the ICH guideline. Both decision methodologies concluded that the assay was valid from 2.13 to 5.83 log(10)(CCID(50)/ml). However, only the Total Error approach using accuracy profile as decision tool allowed to guarantee that accurate and reliable results will be obtained during the future routine application of the assay. In addition, the risk to obtain out of acceptance limits results was estimated using this approach and was found out to be at the most 3.1% irrespective of the concentration level, thus demonstrating the reliability of the biological assay.

e-Health standardization in Europe: lessons learned

Challenges regarding standardization in e-Health are analyzed, and solutions for ensuring their practical implementation are proposed. Emphasis is put on new mechanisms for enhancing the collaboration between the industry and standardization bodies.

Effect of genetic potential and level of feeding on milk protein composition

Two groups of 15 multiparous cows in mid-lactation were used in a Latin square design experiment with 4-week experimental periods. The genetic milk protein concentration level was high in the first group and low in the second. Each group of cows was given in a random order three feeding levels that covered 85, 100 and 115% of energy requirements and 90, 110 and 125% of nitrogen requirements, respeetively. In both groups, increasing level of feeding induced a significant increase in milk yield (+ 2.4 kg/d between lowest and highest levels) and in protein concentration (+ 1.7 g/kg). The proportion of paracasein in total proteins was not altered by either genetics or nutrition. The proportion of casein in total proteins was slightly increased by 0.5 percentage points (P < 0.05) with the intermediate level of feeding. Plasmin and plasminogen activities were not significantly modified by the genetic milk concentration level. Plasmin activity significantly increased with nutrient supplementation, but only in animals of low genetic potential (+ 21% between low and high levels, P < 0.01). Casein composition was not significantly altered by the genetics or level of nutrition. Over the whole range of individual measurements taken (n = 90), the relationships between casein or paracasein and total protein concentrations were linear and very narrow (R2 = 0.92 and 0.95, respectively). The proportion of casein or paracasein in total proteins significantly decreased as plasmin activity increased.