Title Participants Abstract "Influence of print settings on the critical quality attributes of extrusion-based 3D-printed caplets : a quality-by-design approach" "Silke Henry, Lotte De Wever, Valérie Vanhoorne, Thomas De Beer, Chris Vervaet" "Extrusion-based 3D-printing is an easy-to-use, cheap manufacturing technique that could be used to produce tailored precision medicines. The technique has an almost unlimited versatility since a multitude of print parameters can easily be adapted. Unfortunately, little is known of the effect of these print parameters on the critical quality attributes of the resulting printlets. In this study, practical guidelines and means to adapt certain parameters in order to achieve the desired outcome (e.g., acceptable visual quality and flexible dosing) are stipulated for medical 3D-printing using a design-of-experiments approach. The current study aims at elucidating the effect of five print parameters (infill, overlap, number of shells, layer height and layer pattern) on the mechanical properties, dimensions, weight, porosity and dissolution characteristics of a fixed-size caplet consisting of Eudragit EPO (69.3%), Polyox WSR N10 (29.7%) and zolpidem hemitartrate (1%). In terms of the mechanical properties, 3D-printed caplets possessed anisotropy where the vertical compression strength and Brinell hardness exceeded the diametral strength. In general, all 3D-printed caplets possessed acceptable mechanical strength except for a small region of the knowledge space. Dimensional analysis revealed small, statistical significant differences between different runs, although the clinical relevance of this variation is likely negligible. The weight or dose of a caplet can be varied mainly using the infill and overlap and, to a lesser extent, via the layer height and number of shells. The impact on porosity was complicated as this was influenced by many factors and their interactions. Infill was the only statistically relevant factor influencing the dissolution rate of the current formulation. This study unravels the importance of the print parameter overlap, which is a regularly neglected parameter. We also discovered that small dose variations while maintaining the same dissolution profile were possible via modifying the overlap or number of shells. However, large dose variations without affecting the dissolution behaviour could only be accomplished by size modifications of the printlet." "Influence of raw material properties upon critical quality attributes of continuously produced granules and tablets" "Margot Fonteyne, Henrika Wickström, Elisabeth Peeters, Jurgen Vercruysse, Henrik Ehlers, Björn-Hendrik Peters, Chris Vervaet, Jarkko Ketolainen, Niklas Sandler, Jukka Rantanen, Kaisa Naelapää, Thomas De Beer" "Development of critical quality attributes control strategies in a continuous high shear wet granulation process" "Niels Nicolaï, Thomas De Beer, Krist V Gernaey, Ingmar Nopens" "Real-time assessment of critical quality attributes of a continuous granulation process" "Margot Fonteyne, Jurgen Vercruysse, Damián Córdoba Díaz, Delphine Gildemyn, Chris Vervaet, Thomas De Beer" "Identifying critical binder attributes to facilitate binder selection for efficient formulation development in a continuous twin screw wet granulation process" "Lise Vandevivere, Cedrine de Backere, Olaf Häusler, Thomas De Beer, Chris Vervaet, Valérie Vanhoorne" "Continuous twin screw granulation : influence of process and formulation variables on granule quality attributes of model formulations" "Christoph Portier, Kenny Pandelaere, Urbain Delaet, Tamas Vigh, Ashish Kumar, Giustino Di Pretoro, Thomas De Beer, Chris Vervaet, Valérie Vanhoorne" "In recent years, continuous manufacturing techniques, such as twin screw wet granulation, have gained significant momentum. Due to the large diversity of the (model) formulations and equipment, it is often difficult to generalize conclusions about the importance of process settings. As only limited knowledge is available on the importance of formulation variables, this study focused on the systematic quantification of both process as formulation effects on critical quality attributes of granules from several model formulations. Apart from conventional process and formulation variables, also non-conventional process factors such as nozzle diameter, nozzle orientation and inclusion of a new type of size control elements were evaluated using a Plackett-Burman screening design. Although effects were often formulation-dependent, liquid-to-solid ratio proved the most influential variable for all formulations. Furthermore, binder concentration had a clear effect on granule characteristics, whereas barrel fill level and barrel temperature were less influential. The novel type of size control elements improved granule size distribution and density. The impact of nozzle diameter and wet binder addition proved negligible towards granule properties. Overall it was apparent that lactose/MCC-based formulations correlated better than lactose-based formulations, indicating the possible process robustness of the first filler combination to accommodate API and excipient variability and to handle APIs with different characteristics." "Spatial optimization in perfusion bioreactors improves bone tissue-engineered construct quality attributes" "Ioannis Papantoniou, Yann Guyot, Maarten Sonnaert, Greet Kerckhofs, Frank Luyten, Liesbet Geris, Jan Schrooten" "Perfusion bioreactors have shown great promise for tissue engineering applications providing a homogeneous and consistent distribution of nutrients and flow-induced shear stresses throughout tissue-engineered constructs. However, non uniform fluid-flow profiles found in the perfusion chamber entrance region have been shown to affect tissue-engineered construct quality characteristics during culture. In this study a whole perfusion and construct, three dimensional (3D) computational fluid dynamics approach was used in order to optimize a critical design parameter such as the location of the regular pore scaffolds within the perfusion bioreactor chamber. Computational studies were coupled to bioreactor experiments for a case-study flow rate. Two cases were compared in the first instance seeded scaffolds were positioned immediately after the perfusion chamber inlet while a second group was positioned at the computationally determined optimum distance were a steady state flow profile had been reached. Experimental data showed that scaffold location affected significantly cell content and neo-tissue distribution, as determined and quantified by contrast enhanced nanoCT, within the constructs both at 14 and 21 days of culture. However gene expression level of osteopontin and osteocalcin was not affected by the scaffold location. This study demonstrates that the bioreactor chamber environment, incorporating a scaffold and its location within it, affects the flow patterns within the pores throughout the scaffold requiring therefore dedicated optimization that can lead to bone tissue engineered constructs with improved quality attributes. Biotechnol. Bioeng. © 2014 Wiley Periodicals, Inc." "The rehydration attributes and quality characteristics of 'Quick-cooking' dehydrated beans: Implications of glass transition on storage stability" "Shruti Aravindakshan, An Nguyen, Clare Kyomugasho, Ann Van Loey, Marc Hendrickx" "Storage stability is an essential consideration for minimizing the deteriorative quality changes in foods post-processing. This study, for the first, time aimed to gain insight into the storage stability of quick-cooking 'convenient' dehydrated beans (Phaseolus vulgaris L.) using the glass transition (Tg) concept. Quick-cooking dehydrated beans were prepared by hydrothermal treatment of fresh beans followed by air-drying and are rehydrated prior to use. The impact of storage temperatures (25, 28, 35 and 42 °C) on the rehydration indices (rate constant and extent) and quality characteristics (colour, texture and volatile profile) of the beans were studied. The results indicate a decrease in the rehydration rate constants with increasing storage temperatures and duration. The rehydration ability also significantly decreased with increased storage duration (>28 °C) suggesting a strong inverse link with hardness. Although there was no overall colour change with storage, the formation of new volatiles associated with non-enzymatic chemical reactions occurred at elevated temperatures (28-42 °C). Identification of the critical water contents based on the Tg-moisture relation and the moisture sorption isotherm revealed that dehydrated beans of 10 % moisture content stored below 28 °C are in a glassy state. Overall, the quality characteristics are significantly influenced by storage and the utilization of the glass transition concept allows for identifying suitable storage conditions." "Determination of critical factors in malt production related to the flavour stability of final beer" "Flavour instability can be regarded as one of the most important quality problems faced by the brewing industry, as beer flavour starts to deteriorate almost instantly upon packaging. The loss of pleasant flavour attributes and appearance of off-flavours will impact palatability and, therefore, reduce drinkability of beer, which in turn may result in economic losses for the brewer. Efforts to prolong beer freshness may only be fully effective when the complex chemistry behind the phenomena of beer ageing is much better understood. Within this context, one of the current areas of active research is an investigation on the gradual appearance of sensory perceivable off‑flavours during beer transport and storage, which, chemically, coincides with an increase in levels of a multitude of unwanted compounds. Among them particular volatiles, known as 'beer staling aldehydes'. This specific group of aldehydes is characterised by highly flavour‑active compounds, perceived at low concentrations, such as Strecker degradation aldehydes (derived from amino acids), furfural (derived from pentose), and hexanal, as well as trans-2-nonenal (both derived from oxidation of unsaturated fatty acids). Two major mechanisms have been ascribed to the development of staling aldehydes during beer ageing in a package, namely de novo formation of aldehydes from a precursor compound (e.g. an amino acid) and release of aldehydes from a pre-formed bound-state adduct (e.g. cysteinylated aldehydes). It is well-established that the quality of brewing raw materials (in particular malted barley, water, hops, and yeast), as well as the brewing process, affect final beer quality and also beer flavour deterioration. Among raw materials, malt, being the major source of extract, appears to play a pivotal role in beer flavour instability as it has been reported that particular malt quality parameters (such as Kolbach Index, free amino nitrogen content, levels of Strecker aldehydes) are connected to beer staling. Previously, this relationship has also been referred to as the 'beer staling potential of malt'. Interestingly, the same volatile compounds that are directly involved in beer staling, i.e. the above mentioned staling aldehydes, also develop during production of malt. However, unambiguous cause-effect relationships between particular malt constituents and particular compounds in beer (responsible for in-package ageing) have not been proven yet, demonstrating the huge complexity of beer flavour instability and, consequently, the requirement for more research regarding malt and the malting process in relation to this phenomenon. Since during malting both free and bound-state aldehydes already develop, the central objective of this technology-driven PhD is to monitor the malting process in relation to this development and, in particular, to pinpoint critical moments during malting regarding generation of these unwanted compounds. In this regard, in-depth chemical-analytical evaluation of an industrial‑scale malting process and industrial-scale pale lager malts in relation to the formation of (bound-state) aldehydes was performed. Next, targeted micro-malting aiming at malt of reduced beer staling potential and high brewing quality was assessed based on experimental design and numerical modelling. Aiming at a successful assessment of the malting process, the conditions of sample preparation for GC-MS determination of staling aldehydes were optimised for various types of malting samples (i.e. green malt, partially kilned malt, finished pale lager malt). Next, the resulting protocol for determination of volatile, free aldehydes was applied together with an already available method for quantification of non-volatile cysteinylated aldehydes. By applying this approach, we were able to achieve a truly integrated view on both volatile aldehydes and their non-volatile counterparts for malt samples of various origins throughout this whole doctoral study. Moreover, results obtained on (bound-state) aldehydes were assessed in relation to standard quality parameters of various pale lager malts in search for correlations among all of these variables and to improve our understanding of potential relationships that may be relevant to beer flavour instability. Results obtained on industrial-scale samples demonstrated that the content of (cysteinylated) aldehydes in finished malt is clearly higher compared to its starting material, barley. During germination, strong increases in levels of the fatty acid oxidation aldehydes, i.e. hexanal and trans-2-nonenal, were found. Levels in Strecker aldehydes and furfural were, however, hardly affected at this stage. Next, when approaching the stage of drying at elevated temperature (in particular when arriving at a critical moisture content of approx. 6% - 9%), levels of most (cysteinylated) aldehydes showed a first dramatic increase, except for hexanal. Furthermore, levels of all (cysteinylated) aldehydes continued to increase rapidly during kilning-off, except for hexanal. Clearly, throughout this PhD, it was found that hexanal behaves differently compared to all other aldehydes, including the other fatty acid oxidation marker aldehyde, trans-2-nonenal. Furthermore, a clear effect of process-associated physicochemical gradients (caused by pneumatic processing in relatively thick grain beds) on aldehyde formation in malting was demonstrated for the first time. Except for hexanal, the highest levels of free and bound-state aldehydes were found in samples derived from the bottom layer of the grain bed, which is most exposed to heat load during kilning. Accordingly, samples taken at the same time from the upper layer (exposed to significantly less heat load) showed the lowest levels of aldehydes. Next to analysis of the industrial-scale malting process as a function of duration (i.e. stages of malting) and position of the grain in the bed (i.e. bottom, middle, top layer), emphasis was put on several, potentially critical malting variables. These results showed that both the degree of grain modification and kilning-off temperature impact - either indirectly (degree of modification) or directly (kilning-off temperature) - the generation of (cysteinylated) aldehydes during malting. Consequently, the degree of steeping and kilning-off temperature were selected as key variables to conduct additional, targeted micro-malting experiments aimed to investigate the potential feasibility of producing malt of reduced beer staling potential, combined with satisfying brewing quality. Modelling of individual responses, representing the measured aldehydes and malt quality parameters, as a function of the key variables, demonstrated that the steeping degree especially impacts levels of hexanal, whereas kilning-off temperature mainly affects levels of Strecker aldehydes, furfural, and trans-2-nonenal. Finally, numerical modelling of the selected malting variables (steeping degree, kilning-off temperature), suggested the feasibility of producing pale lager malt of superior overall quality on condition that adequate, mutual adjustment of both grain modification and kilning-off temperature is implemented." "Neuromuscular complications of critical illness" "Helena Van Mechelen" "ICU-acquired weakness (ICUAW) is a frequent complication of critical illness. It presents as new onset symmetrical weakness of the peripheral and respiratory muscles during critical illness and cannot be explained by other causes than the acute illness or its treatment. ICUAW is caused by structural or functional damage to the nerves, the muscles or both and occurs in about half of the patients with sepsis, those with multiple organ failure and those receiving prolonged mechanical ventilation. There is no consensus on the gold standard for diagnosis of this complication. Bedside manual muscle strength testing can be performed by trained (para-)medics, provided patients are awake and cooperative, and allows identification of clinically relevant weakness. Alternatively, electrophysiological screening can be used, also in patients who are not conscious. However, the importance of electrophysiological abnormalities, that develop very frequently, and their relationship with clinical weakness have not been explored in large populations. Several observational studies reported an association between ICUAW and poor short-term outcomes. This is not surprising as ICUAW is considered one of the pillars of multiple organ failure, hence reflecting disease severity. In addition, a recent follow-up study in relatively young acute respiratory stress disorder (ARDS) survivors, revealed striking results. First, these patients had a markedly reduced physical function and quality of life persisting up to 5 years following ICU admission. Second, the reduced physical function was mainly attributed to self-perceived weakness. This landmark paper hereby suggested that weakness, which develops in the ICU, may contribute to long-lasting disabilities. This is a very important concept, indicating that ICUAW could also have major socio-economic implications as the population of ICU survivors is rapidly increasing thanks to progress in general supportive measures and mechanical and pharmacological support. Hence, the aim of this doctoral thesis was to gain further insight in the neuromuscular complications of critical illness and the burden entailed by these abnormalities. In a first study, we focused on the question whether ICUAW is just a marker of disease severity or actually contributes to worse outcomes. Because this question does not lend itself to a randomized study design, we used an alternative strategy aimed at reducing bias as much as possible. We prospectively evaluated 415 cooperative long-stay ICU patients (ICU stay ≥8 days) for weakness. All patients were included in the EPaNIC trial. This was a large, randomized controlled trial including 4640 patients that compared early (within 48 hours) with late (not within the first week) parenteral supplementation of deficient enteral feeding. Next, we carefully matched weak to no-weak patients for potential confounders, including baseline characteristics, illness severity and risk factor exposure prior to assessment. This rendered 122 matched pairs of weak and not weak patients. In this matched set, we found that weak patients as compared with not weak patients had worse acute morbidity, indicated by a lower likelihood for early live weaning from mechanical ventilation, live ICU and hospital discharge. Also, health care related hospitalization costs were higher and 1-year mortality was significantly increased in matched weak as compared to matched not-weak patients. These data support that ICUAW actually contributes to poor outcomes. We further demonstrated that persisting weakness at ICU discharge as well as the severity of weakness at that time further compromised 1-year survival. These findings stress the importance of research aimed at preventing this complication. Furthermore, it underscores that a clinical diagnosis of weakness provides important prognostic information. However, a substantial amount of ICU patients is unconscious and uncooperative and cannot reliably perform such voluntary muscle strength tests. Therefore, we evaluated screening electrophysiology as a potential alternative or supplemental diagnostic tool for neuromuscular complications of critical illness in a second study. We explored the diagnostic properties of these electrophysiological screening tests in the ICU with clinically defined weakness as a reference. In addition, we examined the relationship between electrophysiological parameters and 1-year mortality, which we identified in the previous study as an important patient-centered outcome affected by ICUAW. We again focused on long-stay EPaNIC patients (ICU stay ≥8 days) at increased risk for neuromuscular complications. In addition, given the high incidence of electrophysiological abnormalities in critically ill patients and as the incidence of such abnormalities in ICU patients with a favorable recovery is unknown, it was very important for this research question to also include a random sample of short-stay patients. A total of 730 patients, of whom 88 short-stayers received screening electrophysiology and 432 of these patients were clinically evaluable for muscle strength. Screening electrophysiology showed that 1 week after ICU admission none of the electrophysiological parameters demonstrated both high sensitivity and high specificity for weakness and therefore cannot simply be used as a substitute. However, normal compound muscle action potential (CMAP) excluded weakness with a high negative predictive value. Strikingly, abnormal CMAP 1 week after ICU admission was associated with increased 1-year mortality, independent from weakness. These data indicate that electrophysiology provides information supplementing clinical data and suggests that patients with either weakness or early abnormal CMAP may benefit from close follow-up, also after hospital discharge. Finally, we aimed to assess long-term recovery of muscle strength and related functional status in general survivors of critical illness and to identify factors associated with persisting impairment within this post-ICU period. For this purpose, we prospectively evaluated 117 EPaNIC patients 2 years after ICU admission. To reduce bias from patient selection, also home visits were performed. Data were compared with those obtained from 50 demographically matched controls. Results demonstrated that ICU survivors were significantly weaker than controls. This was associated with reduced functional status and accompanied by reduced quality of life. Paired biopsy samples from 8 of these patients who received a muscle biopsy in the ICU and at 2-year follow-up showed that myofiber atrophy is more pronounced 2 years after critical illness as compared to 1 week after ICU admission. These data indicate that persisting limitations are present, also in general ICU survivors, up to 2 years following ICU admission and suggest that the legacy of critical illness is not limited to ARDS patients. Furthermore, we demonstrated in 43 of these patients who were also evaluated after 1 year, that handgrip strength and maximal exercise capacity deteriorated within this time frame. Further research should identify potentially modifiable risk factors for this decline. In conclusion, muscle weakness acquired during critical illness carries a burden both in terms of short-term morbidity as well as 1-year mortality. Weakness persists 2 years after critical illness and is accompanied by poor functional status and quality of life."