Assisted Active Learning for Model-Based Method Development in Liquid Chromatography.

In recent decades, there has been a growing interest in fully automated methods for tackling complex optimization problems across various fields. Active learning (AL) and its variant, assisted active learning (AAL), incorporating guidance or assistance from external sources into the learning process, play key roles in this automation by enabling the autonomous selection of optimal experimental conditions to efficiently explore the problem space. These approaches are particularly valuable in situations wherein experimentation is costly or time-consuming.

Application of design space and quality by design methodologies combined with ultra high-performance liquid chromatography for the optimization of the sample preparation of complex pharmaceutical dosage forms.

Accurate and precise analytical measurements play a significant role in assessments and decisions that are made throughout the drug development process. Developing a robust and reliable sample preparation is essential for drug product formulations to generate consistent results guaranteeing the product quality. However, due to the complex nature of the different pharmaceutical formulations with diverse excipients, developing robust sample preparation methods can be challenging and time consuming.

Development of an achiral-chiral 2-dimensional heart-cutting platform for enhanced pharmaceutical impurity analysis.

A new broadly applicable achiral-chiral 2-dimensional heart-cutting (LC-LC) platform is designed comprising a multi-column selection approach in the chiral dimension. As both dimensions are operated in a highly aqueous reversed-phase type mode, analysis of a broad range of pharmaceutical solutes (LogP: 1.49-5.

Model-based NIR spectroscopy implementation for in-line assay monitoring during a pharmaceutical suspension manufacturing process.

The implementation of Process Analytical Technology (PAT) instruments is generally achieved stochastically. Sub-optimal PAT locations could introduce variation in the measurements which is not related to the analyte of interest. For this reason, rational approaches should be considered to establish an optimal sensor placement where relevant measurements are possible and the impact of disturbances is minimized.

In-line UV spectroscopy for the quantification of low-dose active ingredients during the manufacturing of pharmaceutical semi-solid and liquid formulations.

UltraViolet (UV) spectroscopy was evaluated as an innovative Process Analytical Technology (PAT) - tool for the in-line and real-time quantitative determination of low-dosed active pharmaceutical ingredients (APIs) in a semi-solid (gel) and a liquid (suspension) pharmaceutical formulation during their batch production process. The performance of this new PAT-tool (i.e.

Flow cytometric enumeration of bacteria using TO-PRO®-3 iodide as a single-stain viability dye.

Quantification of bacteria using conventional viable plate counting (VPC) is labor-intensive and time-consuming. Flow cytometry (FCM) can be proposed as a faster alternative. This study aimed to develop a flow cytometric, single-stain approach using TO-PRO®-3 iodide (TP3) for the quantification of Staphylococcus aureus, Escherichia coli, and Bacillus subtilis cells.

NIR spectroscopic method for the in-line moisture assessment during drying in a six-segmented fluid bed dryer of a continuous tablet production line: Validation of quantifying abilities and uncertainty assessment.

This study focuses on the thorough validation of an in-line NIR based moisture quantification method in the six-segmented fluid bed dryer of a continuous from-powder-to-tablet manufacturing line (ConsiGma™ 25, GEA Pharma Systems nv, Wommelgem, Belgium). The moisture assessment ability of an FT-NIR spectrometer (Matrix™-F Duplex, Bruker Optics Ltd, UK) equipped with a fiber-optic Lighthouse Probe™ (LHP, GEA Pharma Systems nv, Wommelgem, Belgium) was investigated. Although NIR spectroscopy is a widely used technique for in-process moisture determination, a minority of NIR spectroscopy methods is thoroughly validated.

Particle sizing measurements in pharmaceutical applications: comparison of in-process methods versus off-line methods.

It has been previously described that when a sample's particle size is determined using different sizing techniques, the results can differ considerably. The purpose of this study was to review several in-process techniques for particle size determination (Spatial Filtering Velocimetry, Focused Beam Reflectance Measurements, Photometric Stereo Imaging, and the Eyecon® technology) and compare them to well-known and widespread off-line reference methods (laser diffraction and sieve analysis). To start with, a theoretical explanation of the working mechanism behind each sizing technique is presented, and a comparison between them is established.

Robust calibrations on reduced sample sets for API content prediction in tablets: definition of a cost-effective NIR model development strategy.

Owing to spectral variations from other sources than the component of interest, large investments in the NIR model development may be required to obtain satisfactory and robust prediction performance. To make the NIR model development for routine active pharmaceutical ingredient (API) prediction in tablets more cost-effective, alternative modelling strategies were proposed. They used a massive amount of prior spectral information on intra- and inter-batch variation and the pure component spectra to define a clutter, i.

Quantification of Candida albicans by flow cytometry using TO-PRO(®)-3 iodide as a single-stain viability dye.

This study investigated a flow cytometric, single-stain approach to quantify Candida albicans as an alternative for the standard viable plate count. TO-PRO(®)-3 iodide allows an excellent distinction between viable and dead cells. Both quantification methods show a high degree of correlation.

Development of a fluid bed granulation process control strategy based on real-time process and product measurements.

This article describes the results of three case studies conducted consecutively, in order to develop a process control strategy for a top-spray fluid bed granulation process. The use of several real-time particle size (i.e.

Batch statistical process control of a fluid bed granulation process using in-line spatial filter velocimetry and product temperature measurements.

Fluid bed granulation is a batch process, which is characterized by the processing of raw materials for a predefined period of time, consisting of a fixed spraying phase and a subsequent drying period. The present study shows the multivariate statistical modeling and control of a fluid bed granulation process based on in-line particle size distribution (PSD) measurements (using spatial filter velocimetry) combined with continuous product temperature registration using a partial least squares (PLS) approach. Via the continuous in-line monitoring of the PSD and product temperature during granulation of various reference batches, a statistical batch model was developed allowing the real-time evaluation and acceptance or rejection of future batches.

Evaluation of in-line spatial filter velocimetry as PAT monitoring tool for particle growth during fluid bed granulation.

In this study, the feasibility of spatial filter velocimetry (SFV) as process analytical technology tool for the in-line monitoring of the particle size distribution during top spray fluidized bed granulation was examined. The influence of several process (inlet air temperature during spraying and drying) and formulation variables (HPMC and Tween 20 concentration) upon the particle size distribution during processing, and the end product particle size distribution, tapped density and Hausner ratio was examined using a design of experiments (DOE) (2-level full factorial design, 19 experiments). The trend in end granule particle size distributions of all DOE batches measured with in-line SFV was similar to the off-line laser diffraction (LD) data.

Tryptophan rotamers as evidenced by X-ray, fluorescence lifetimes, and molecular dynamics modeling.

We investigated the native-state dynamics of the Bacillus caldolyticus cold-shock protein mutant Bc-Csp L66E, using fluorescence and appropriate molecular dynamics methods. Two fluorescence lifetimes were found, the amplitudes of which agree very well with tryptophan rotamer populations, obtained from parallel tempering calculations. Rotamer lifetimes were predicted by transition-state theory from high-temperature simulations.

Experimental indication for the existence of multiple Trp rotamers in von Willebrand Factor A3 domain.

The first step in both normal haemostasis and arterial thrombosis is the interaction between collagen, von Willebrand factor (vWF), and glycoprotein Ib. The A3 domain of vWF forms the principal binding site for collagen type I and type III. Inhibition of the vWF-collagen interaction by an anti-human vWF monoclonal antibody (MoAb) 82D6A3 can be a potential way to prevent arterial thrombosis.

The dead-end elimination method, tryptophan rotamers, and fluorescence lifetimes.

The Dead-End Elimination method was used to identify 40 low energy microconformations of 16 tryptophan residues in eight proteins. Single Trp-mutants of these proteins all show a double- or triple-exponential fluorescence decay. For ten of these lifetimes the corresponding rotameric state could be identified by comparing the bimolecular acrylamide quenching constant (k(q)) and the relative solvent exposure of the side chain in that microstate.

Conformational states of the switch I region of Ha-ras-p21 in hinge residue mutants studied by fluorescence lifetime and fluorescence anisotropy measurements.

The hinge residues (Val29 and Ile36) of the switch I region (also known as the effector loop) of the Ha-ras-p21 protein have been mutated to glycines to accelerate the conformational changes typical for the effector loop. In this work, we have studied the influence of the combined mutations on the steady-state structure of the switch I region of the protein in both the inactive GDP-bound conformation as in the active GTP-bound conformation. Here, we use the fluorescence properties of the single tryptophan residue in the Y32W mutant of Ha-ras-p21.

Photochemical generation of a primary vinyl cation from (E)-bromostyrene: mechanisms of formation and reaction.

The photochemistry of (E)-bromostyrene was investigated to determine the nature of the product-forming intermediates and to clarify the mechanism of formation of vinylic cations and vinylic radicals. Both a cation- and a radical-derived product are formed, and the ionic origin of the former product is demonstrated by significant scrambling of the label, starting from specifically deuterated (E)-bromostyrene. MO calculations show that the isolated incipient primary vinyl cation is not a metastable species, but that specific interaction with a counterion in combination with a polar environment makes it metastable.

[Culling of animals in large herds, experiences from the Netherlands].

The outbreaks of classical swine fever in 1997-1998 and foot- and mouth-disease in 2001 provided a lot of experiences in the culling of animals. These experiences, as well as the aspects of animal welfare and public acceptance are described. In the future these experiences will help to carry out culling in a more efficient way including improved aspects of animal welfare and public acceptance.

A self-expanding endoluminal graft for treatment of aneurysms: results through the development phase.

Background: The results of two and a half years' experience of endoluminal treatment of aneurysmal disease (from March 1993 to December 1995) are reported.

Methods: The endoluminal grafts were individually made at Royal Perth Hospital. They are based on Dacron-covered stainless steel self-expanding 'Z' stents with Gianturco barbed stents (Cook Pty, Australia) for proximal anchorage for grafts within the aorta.

The quality of blood used for transfusion.

The current risk of disease transmission through homologous blood transfusion has lead to a revival in the use of autologous blood. The development of a coagulopathy increases the usage of blood and blood products and therefore the risk of disease transmission. Blood salvaged at operation is subjected to physical and humoral activating factors.

Lipolytic enzyme and phospholipid level changes in intraoperative salvaged blood.

Autotransfusion is becoming increasingly popular, mainly because it eliminates the risk of disease transmission. One of the techniques available is intra-operative blood salvage and retransfusion with or without washing of the collected blood. The blood collected during this process is subjected to a variety of chemical and physical insults which can alter the normal composition of the plasma by activating plasma and cellular homeostatic mechanisms.