Urinary calcium excretion. (Normal values for urinary calcium/creatinine ratio in Hungary). Multicenter study

Metabolic bone disorders have attracted increasing attention in Hungary due to their significant impact on public health care. Measuring urinary calcium excretion is the first step in the biochemical assessment of bone metabolism. Fasting urinary calcium corrected by creatinine excretion is widely used all over the world. The aim of the present study was to establish standard methods and normal values for the calcium/creatinine ratio in Hungary. Twenty-four centers specializing in metabolic bone diseases participated in the study. Urine standards were sent out to these centers for calcium and creatine determinations. Based on the collected data, methods were corrected in order to achieve similar results for the standards. In the second phase of the study, the normal values for calcium/creatinine ratio were determined in SI units based on the data from 1846 healthy subjects (age 20-80 yrs) including 944 females and 902 males. The normal value for females was 0.438 +/- 0.391 (means +/- SD), and 0.395 +/- 0.352 for males, respectively (p < 0.03). The ratio increased with age in both sexes. The highest values were observed between 60-64 years in women and 70-74 years in men, respectively. After this peak, the calcium/creatinine ratio decreased. The values before and after 45 years of age were significantly different both in women (0.37 +/- 0.36, vs. 0.52 +/- 0.41, p < 0.001; and men (0.32 +/- 0.23, vs. 0.47 +/- 0.45, p < 0.001). The use of this distinction is recommended in the everyday practice.     

Investigation and simulation of crystallization of high aspect ratio crystals with fragmentation

Background

Crystallization is a widely used unit operation in the pharmaceutical industry where high aspect ratio crystals are often produced. To avoid undesired shape i.e. high aspect ratio crystals according to downstream operations, appropriate level of understanding process is necessary. Breakage often occurs during the process and gives rise to change the Crystal shape. A well-adjusted, detailed model can be usable tool for investigation and optimization of control.

Method

A two-dimensional population balance model of continuous cooling crystallization, involving nucleation, growth of two characteristic crystal facets and random binary breakage of high aspect ratio crystals is developed. The randomness of breakage is described by beta distribution of broken fractions. The population balance model is reduced into a closed moment equation model for the joint moments of the two size variables of crystals by means of which the influence of parameters of breakage on the dynamic and steady state behavior of crystallizer is analyzed according to understand the impact of complex kinetic on crystal shape.

Results

Analysis of the process provides information of breakage influence on aspect ratio of crystal. It is shown that the mean value of crystal width increases as the intensity of breakage along the crystal length resulted in increasing number of crystals.     

Novel Polyurethane Scaffolds Containing Sucrose Crosslinker for Dental Application

In this paper, the synthesis, characterization, and properties of crosslinked poly(ε-caprolactone)-based polyurethanes as potential tissue replacement materials are reported. The polyurethane prepolymers were prepared from poly(ε-caprolactone)diol (PCD), polyethylene glycol (PEG)/polylactic acid diol (PLAD), and 1,6-hexamethylene diisocyanate (HDI). In these segmented polyurethanes, the role of PEG/PLAD was to tune the hydrophobic/hydrophilic character of the resulting polymer while sucrose served as a crosslinking agent. PLAD was synthesized by the polycondensation reaction of D,L-lactic acid and investigated by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and nuclear magnetic resonance spectroscopy (NMR). The crosslinked polyurethane samples (SUPURs) obtained were characterized by attenuated total reflectance Fourier-transform infrared spectroscopy (AT-FT-IR), swelling, and mechanical (uniaxial tensile tests) experiments. The thermo and thermomechanical behavior were studied by differential scanning calorimetry (DSC) and dynamical mechanical analysis (DMA). The viability of dental pulp stem cells was investigated in the case of polyurethanes composed of fully biocompatible elements. In our studies, none of our polymers showed toxicity to stem cells (DPSCs).