Can 3D Printed Tablets Be Bioequivalent and How to Test It: A PBPK Model Based Virtual Bioequivalence Study for Ropinirole Modified Release Tablets.

As the field of personalized dosing develops, the pharmaceutical manufacturing industry needs to offer flexibility in terms of tailoring the drug release and strength to the individual patient's needs. One of the promising tools which have such capacity is 3D printing technology. However, manufacturing small batches of drugs for each patient might lead to huge test burden, including the need to conduct bioequivalence trials of formulations to support the change of equipment or strength. In this paper we demonstrate how to use 3D printing in conjunction with virtual bioequivalence trials based on physiologically based pharmacokinetic (PBPK) modeling. For this purpose, we developed 3D printed ropinirole formulations and tested their bioequivalence with the reference product Polpix. The Simcyp simulator and previously developed ropinirole PBPK model were used for the clinical trial simulations. The Weibull-fitted dissolution profiles of test and reference formulations were used as inputs for the model. The virtual bioequivalence trials were run using parallel design. The study power of 80% was reached using 125 individuals. The study demonstrated how to use PBPK modeling in conjunction with 3D printing to test the virtual bioequivalence of newly developed formulations. This virtual experiment demonstrated the bioequivalence of one of the newly developed formulations with a reference product available on a market.

The influence of microinjection parameters on cell survival and procedure efficiency.

Microinjection is a method commonly used to deliver various substances into cells. The procedure is performed on a widefield microscope stage using fine glass needle to penetrate the cell membrane. Microinjection can be carried out using a manual or semi-automatic mode. For commercially available equipment currently reported microinjection success rate and cell viability are relatively low (around 50% for both indicators). Here, for the first time, we systematically show how the microinjection effectiveness and cell viability are influenced by needle diameter and chosen microinjection mode. We found that manual mode entailed a higher injection rate, reducing cell viability at the same time. The reduction in needle diameter caused a significant increase in cell survival rate (from 43 to 73% for manual mode and from 58% to 86% for semi-automatic mode) and did not affect significantly the success rate. Our findings will help optimize this method in the context of cell biology research.•This study shows how to improve microinjection parameters, such as procedure efficiency and cell survival rate, for commercially available equipment.•Manual mode, in comparison with semi-automatic mode, results in higher microinjection efficiency, but lower cell survival rate.•The increase in micropipette diameter causes lower cell viability and a higher microinjection success rate.

Design and Construction of a Chamber Enabling the Observation of Living Cells in the Field of a Constant Magnetic Force.

The aim of the work was to design and construct a microscopic stage that enables the observation of biological cells in a magnetic field with a constant magnetic force. Regarding the requirements for biological observations in the magnetic field, construction was based on the standard automatic stage of an optical microscope ZEISS Axio Observer, and the main challenge was to design a set of magnets which were the source of a field in which the magnetic force was constant in the observation zone. Another challenge was to design a magnet arrangement producing a weak magnetic field to manipulate the cells without harming them. The Halbach array of magnets was constructed using permanent cubic neodymium magnets mounted on a 3D printed polymer ring. Four sets of magnets were used, differing in their dimensions, namely, 20, 15, 12, and 10 mm. The polymer rings were designed to resist magnetic forces and to keep their shape undisturbed when working under biological conditions. To check the usability of the constructs, experiments with magnetic microparticles were executed. Magnetic microparticles were placed under the microscope and their movement was observed to find the acting magnetic force.

Physics Doesn't Bite-A Simple Experiment for Introducing Biomechanical Operational Principles of the Temporomandibular Joint.

Biophysics is rarely mentioned as one of the most useful parts of dental and medical students' curricula. However, with the growing complexity of tools and methods used in diagnostics and therapy, the knowledge of their physical foundations becomes important and helps with choosing the optimal solutions for both, a patient and a doctor. The aim of the proposed activity is to develop students' intuition about simple physical models that help with understanding fundamental properties of temporomandibular joint (TMJ). A simple device, which allows for bite force measurement, is proposed. It is based on beam bending and a strain gauge Wheatstone bridge circuit mounted on two connected arms: the stiff one and the more elastic one. Linear regression is the only mathematical concept needed for understanding the physical background of the proposed activity. During the proposed activity-measuring of bite force for incisors, premolars, and molars-students are confronted with basic concepts, such as lever, torque, electrical circuit, calibration curve. By utilizing a simple idea, instead of a commercially available device, students can understand where the data come from. Proposed system delivers physiologically reasonable results.

Effect of Education for Hypertensive Patients with Correctly Performed Self-Blood Pressure Monitoring (SBPM).

INTRODUCTION: The study objective was to assess the impact of pharmacist-led education on the patient's knowledge and skills on SBPM (self-blood pressure monitoring). METHODS: Patient knowledge was assessed using tests and patients' skills were based on a checklist (20 parameters) completed by the researcher based on the SBPM video records. Patients taking pressure measurements were filmed for 20 days and after 6 months. After the first 10 days, patients were educated about the correct SBPM procedure. Knowledge tests were repeated three times (before/after/6 months after education). RESULTS: All patients' knowledge and skills in the field of SBPM were improved after education. After the education, patients scored an average of 9 out of 10 points in the knowledge test (increasing an average of five points after education), six months later-an average increase of 7.36 points. Patient skills after training were rated at 17.4 out of 20 points on average (increase by an average of 5.14 points after education), six months later, there was an average of 16.23 points. CONCLUSIONS: The study showed an increase in patients' knowledge and skills in the field of SBPM after training.

Outbreaks of the measles in the Dutch Bible Belt and in other places - New prospects for a 1000 year old virus.

In the Netherlands there has been nationwide vaccination against the measles since 1977. However, a tight-knit community of a few hundred thousand orthodox protestants in the "Dutch Bible Belt" refuses the vaccine. Within this community of orthodox protestants there has been an outbreak of the measles with roughly 2500 reported cases about every twelve years. Each outbreak has lasted about a year. The community of orthodox protestants is too small to permanently keep the virus in circulation and have the infection be endemic. The dynamics in orthodox-protestant schools has been widely recognized as the engine behind the epidemic outbreaks. It is shown how these dynamics are a kind of integrate-and-fire mechanism: new susceptibles enter the denominational schools until a critical mass is reached and an outbreak occurs. From a public health perspective, periodic outbreaks of the measles are worse than an endemic situation. When the measles was endemic, almost every child would get infected at around the age of ten. This is also the age at which one is best able to cope with the disease. With the short periodic outbreaks, a significant fraction of the orthodox-protestant, schoolgoing population does not get infected during an outbreak. These "escapees," however, may then get infected during a next outbreak when they are adults and less well-equipped to handle the disease. The three subsequent outbreaks in the Dutch Bible Belt (1988, 1999, 2013) have indeed shown increasingly many adult cases and hospitalizations. As vaccination rates in the developed world are decreasing, the situation in the Dutch Bible Belt is duplicated in other places. We point out how in some large European cities the relevant parameters resemble those in the Dutch Bible Belt. We, furthermore, provide extensive background on the thousand year relation between humanity and the measles virus.

Drug interaction at hERG channel: In vitro assessment of the electrophysiological consequences of drug combinations and comparison against theoretical models.

Drugs carry a proarrhythmic risk, which gets even greater when they are used in combination. In vitro assessment of the proarrhythmic potential of drugs is limited to one compound and thus neglects the potential of drug-drug interactions, including those involving active metabolites. Here we present the results of an in vitro study of potential drug-drug interactions at the level of the hERG channel for the combination of up to three compounds: loratadine, desloratadine and ketoconazole. Experiments were performed at room temperature on an automated patch-clamp device CytoPatch 2, with the use of heterogeneously, stably transfected HEK cells. Single drugs, pairs and triplets were used. The results provided as the inhibition of the IKr current for pairs were compared against the calculated theoretical interaction. Models applied to calculate the combined effect of inhibitory actions of simultaneously given drugs include: (1) simple additive model with a maximal inhibition limit of 1 (all channels blocked in 100%); (2) Bliss independence; and (3) Loewe additivity. The observed IC50 values for loratadine, desloratadine and ketoconazole were 5.15, 1.95 and 0.74 µm respectively. For the combination of drugs tested in pairs, the effect was concentration dependent. In lower concentrations, the synergistic effect was observed, while for the highest tested concentrations it was subadditive. To triple the effect, it was subadditive regardless of concentrations. The square root of sum of squares of differences between the observed and predicted total inhibition was calculated to assess the theoretical interaction models. For most of the drugs, the allotopic model offered the best fit.

Phase transitions and entropies for synchronizing oscillators.

We study a generic model of coupled oscillators. In the model there is competition between phase synchronization and diffusive effects. For a model with a finite number of states we derive how a phase transition occurs when the coupling parameter is varied. The phase transition is characterized by a symmetry breaking and a discontinuity in the first derivative of the order parameter. We quantitatively account for how the synchronized pulse is a low-entropy structure that facilitates the production of more entropy by the system as a whole. For a model with many states we apply a continuum approximation and derive a potential Burgers' equation for a propagating pulse. No phase transition occurs in that case. However, positive entropy production by diffusive effects still exceeds negative entropy production by the shock formation.

Stepping molecular motor amid Lévy white noise.

We consider a model of a stepping molecular motor consisting of two connected heads. Directional motion of the stepper takes place along a one-dimensional track. Each head is subject to a periodic potential without spatial reflection symmetry. When the potential for one head is switched on, it is switched off for the other head. Additionally, the system is subject to the influence of symmetric, white Lévy noise that mimics the action of external random forcing. The stepper exhibits motion with a preferred direction which is examined by analyzing the median of the displacement of a midpoint between the positions of the two heads. We study the modified dynamics of the stepper by numerical simulations. We find flux reversals as noise parameters are changed. Speed and direction appear to very sensitively depend on characteristics of the noise.

"Cargo-mooring" as an operating principle for molecular motors.

Navigating through an ever-changing and unsteady environment, and utilizing chemical energy, molecular motors transport the cell׳s crucial components, such as organelles and vesicles filled with neurotransmitter. They generate force and pull cargo, as they literally walk along the polymeric tracks, e.g. microtubules. What we suggest in this paper is that the motor protein is not really pulling its load. The load is subject to diffusion and the motor may be doing little else than rectifying the fluctuations, i.e. ratcheting the load׳s diffusion. Below we present a detailed model to show how such ratcheting can quantitatively account for observed data. The consequence of such a mechanism is the dependence of the transport׳s speed and efficacy not only on the motor, but also on the cargo (especially its size) and on the environment (i.e. its viscosity and structure). Current experimental works rarely provide this type of information for in vivo studies. We suggest that even small differences between assays can impact the outcome. Our results agree with those obtained in wet laboratories and provide novel insight in a molecular motor׳s functioning.

How in vitro influences in silico utilized for the prediction of in vivo - pilot study of the drug-induced pro-arrhythmic potency prediction.

The current drug cardiac safety risk assessment paradigm is about to be changed. The discussed modifications cover clinical as well as pre-clinical sides. As for the latter, the pre-clinical assessment, it is planned to be based on the analysis of the drug-triggered multiple ion currents inhibition. Considering the variability in the in vitro patch clamp studies results, it would be of benefit to assess how these apparatus- and protocol-dependent differences influence the risk prediction and, eventually, the decision making. Four compounds, namely dextromethorphan, ketoconazole, terfenadine, and quinidine were screened for hERG inhibition with an automated patch clamp apparatus (CytoPatch(TM)2). The results were then compared against the literature published data, and after being complemented with information about other current inhibitions and effective therapeutic plasma concentration, utilized for the in silico based safety assessment. Two endpoints were used: (1) the concentration dependent potential to induce early afterdepolarizations in the simulated action potential and (2) the arrhythmia-like disruption in the simulated pseudo-ECG signals. Data analysis results prove that IC50 values, describing the inhibition potential, significantly differ among studies, and the choice of input data can greatly influence the in silico based safety assessment and thus the decision making process.