Search Results

You are looking at 1 - 5 of 5 items for

  • Author or Editor: J. Ulrich x
  • All content x
Clear All Modify Search

The application of solid layer crystallization techniques in industry is arousing ever more interest. One reason is the increasing demand for ultrapure products, and another is the energysaving potential of this separation technology.

Restricted access

Abstract  

An increase of the specific surface area of solid phases is often desirable e.g. for the bioavailability of pharmaceuticals or in chemical processes. Such an increase can a.o. be achieved by suspending crystalline substances in a solvent that induces phase transformations. Hence, the original substance has to be in a metastable state in the solvent. If the stable phase after transformation has in addition a very low solubility in the solvent, a dendritic growth is forced to occur because of the high local supersaturations during the phase change. This dendritic growth of the stable phase in term leads to needle- or whisker-like crystals, which have the desired larger specific surface area in comparison to the initial crystalline substance.In order to investigate this phenomenon several hydrates of salts were chosen, which undergo phase transformations to their anhydrates accompanied by a corresponding loss of crystal water when suspended in excess in lower alcohols. Consequently, anhydrous forms were created by dehydrating these hydrates. The transformation rate or in this case the dehydration level can thus be indirectly measured by Karl-Fischer titration. The thermodynamic background of the dehydration phenomena can be clarified by solubility studies of the hydrates and anhydrates in water/alcohol-mixtures.

Restricted access

Abstract  

The aim of this work was to investigate the influence of different levels of microwave irradiation on the structure and particle size characteristics of α-lactose monohydrate. The structural study of the samples was carried out by XRD, the presence of lactose polymorphs in the test samples was determined by DSC and the particle size distribution was measured by laser diffraction. The samples subjected to microwave irradiation retained their original X-ray patterns. No significant differences in thermal transition characteristics and particle size were observed. Hence, neither the occurrence of crystalline-amorphous transition resulted by microwave irradiation nor the presence of lactose polymorphs in the test samples can be assumed. The unmodified properties can be attributed to the fact that the water of crystallization is very difficult to remove from the crystal structure and is not free to move during microwave treatment, which results in stability to microwaves. Our results allow the conclusion that microwave processing of α-lactose monohydrate has no influence on further pharmaceutical technological properties, which are related to the structure and the particle size distribution of this substance.

Restricted access
Physiology International
Authors: HI Korkmaz, NE Hahn, KM Jansen, RJP Musters, J van Bezu, WN van Wieringen, PPM van Zuijlen, MMW Ulrich, HWM Niessen, and PAJ Krijnen

Purpose

We previously found that homocysteine (Hcy)-induced apoptosis in endothelial cells coincided with increased NADPH oxidase (NOX) activity. In addition, in ischemic endothelial cells present in the heart, we showed that loss of serine protease dipeptidyl peptidase IV (DPP4) expression was correlated with induction of tissue factor (TF) expression. Since Hcy can initiate thrombosis through the induction of TF expression, in this study, we evaluated whether the inverse relation of TF and DPP4 is also Hcy-dependent and whether NOX-mediated reactive oxygen species (ROS) is playing a role herein.

Methods

Human umbilical vein endothelial cells (HUVECs) were incubated with 2.5 mM Hcy for 3 and 6 h. The effects of Hcy on DPP4 and TF expression and NOX2/p47phox-mediated nitrotyrosine (ROS) production were studied using digital-imaging microscopy.

Results

In HUVECs, high levels of Hcy showed a significant increase of TF expression and a concomitant loss of DPP4 expression after 6 h. In addition, NOX subunits NOX2 and p47phox were also significantly increased after 6 h of Hcy incubation and coincided with nitrotyrosine (ROS) expression. Interestingly, inhibition of NOX-mediated nitrotyrosine (ROS) with the use of apocynin not only reduced these effects, but also counteracted the effects of Hcy on TF and DPP4 expression.

Conclusion

These results indicate that the inverse relation of TF and DPP4 in endothelial cells is also Hcy-dependent and related to NOX activity.

Restricted access

Including gaming disorder in the ICD-11: The need to do so from a clinical and public health perspective

Commentary on: A weak scientific basis for gaming disorder: Let us err on the side of caution (van Rooij et al., 2018)

Journal of Behavioral Addictions
Authors: Hans-Jürgen Rumpf, Sophia Achab, Joël Billieux, Henrietta Bowden-Jones, Natacha Carragher, Zsolt Demetrovics, Susumu Higuchi, Daniel L. King, Karl Mann, Marc Potenza, John B. Saunders, Max Abbott, Atul Ambekar, Osman Tolga Aricak, Sawitri Assanangkornchai, Norharlina Bahar, Guilherme Borges, Matthias Brand, Elda Mei-Lo Chan, Thomas Chung, Jeff Derevensky, Ahmad El Kashef, Michael Farrell, Naomi A. Fineberg, Claudia Gandin, Douglas A. Gentile, Mark D. Griffiths, Anna E. Goudriaan, Marie Grall-Bronnec, Wei Hao, David C. Hodgins, Patrick Ip, Orsolya Király, Hae Kook Lee, Daria Kuss, Jeroen S. Lemmens, Jiang Long, Olatz Lopez-Fernandez, Satoko Mihara, Nancy M. Petry, Halley M. Pontes, Afarin Rahimi-Movaghar, Florian Rehbein, Jürgen Rehm, Emanuele Scafato, Manoi Sharma, Daniel Spritzer, Dan J. Stein, Philip Tam, Aviv Weinstein, Hans-Ulrich Wittchen, Klaus Wölfling, Daniele Zullino, and Vladimir Poznyak

The proposed introduction of gaming disorder (GD) in the 11th revision of the International Classification of Diseases (ICD-11) developed by the World Health Organization (WHO) has led to a lively debate over the past year. Besides the broad support for the decision in the academic press, a recent publication by van Rooij et al. (2018) repeated the criticism raised against the inclusion of GD in ICD-11 by Aarseth et al. (2017). We argue that this group of researchers fails to recognize the clinical and public health considerations, which support the WHO perspective. It is important to recognize a range of biases that may influence this debate; in particular, the gaming industry may wish to diminish its responsibility by claiming that GD is not a public health problem, a position which maybe supported by arguments from scholars based in media psychology, computer games research, communication science, and related disciplines. However, just as with any other disease or disorder in the ICD-11, the decision whether or not to include GD is based on clinical evidence and public health needs. Therefore, we reiterate our conclusion that including GD reflects the essence of the ICD and will facilitate treatment and prevention for those who need it.

Open access