Microstructural investigations of strain-related collagen mineralization

Distraction osteogenesis in rabbit mandibles after osteotomy can be used as an experimental model to study the microstructural features of mineralization of callus under defined mechanical loads. Our aim was to study the relation between the micromotions in the gap and the resulting features of mineralization of the matrix. We found that assembly of collagen and formation of crystals depended on the magnitude of the mechanical stress applied. At physiological bone strains (2000 microstrains), the callus had collagen type I in a mature bone-like extracellular arrangement, whereas at 20000 microstrains bundles were orientated predominantly towards the tension vector. Maximum loads (200000 microstrains) resulted in disorganized assembly of the collagen. Quantitative energy-dispersive analysis by X-rays confirmed that high strains were associated with substantially lower concentrations of calcium and phosphate. In contrast to bone-like apatitic formation of crystals at physiological strains, significantly fewer but larger crystals were detected by electron diffraction analysis in samples exposed to high strains. We suggest that mechanical stress regulates the assembly and mineralization of collagen during distraction osteogenesis.     

Behandlung von frontobasalen Traumen und Polytraumen

Background: This paper describes the historical development as well as current concepts of frontobasal fracture treatment by maxillofacial surgeons. Treatment concept: Based on the experience of many years a diagnostic and therapeutic treatment concept was developed, which proved to be adequate in 320 patients with 90 frontobasal fractures in the last five years.     

Electrochemistry of some novel hole transport materials

Several charge transfer agents have been investigated using cyclic voltammetry. We report multistep mechanisms involving both chemical and electrochemical steps, for the three compounds in the study. The overall mechanism consists of two quasi-reversible electron transfer events, each followed by a chemical step, an ECEC mechanism. The first cyclic voltammetric wave for each compound was studied separately. After the second quasi-reversible electron transfer, a third oxidation wave is observed under conditions of high concentration and slower scan rates. This is attributed to direct oxidation of the product of the second chemical step, which is identified as oligomer formation. This hypothesis is consistent with the physically observed formation of a film on the surface of the electrode, presumably from electrooxidative oligomerization of the compound.     

Course of changes in salivary pH-values after intake of different beverages in young children

PURPOSE: The aim of the study was to determine possible differences in decrease of pH-values of whole saliva, following the intake of different beverages. MATERIALS AND METHODS: Twelve boys and 13 girls (4.9 +/- 0.9 years old) participated in this study. A dental examination was performed (dmft). Orange juice (pH = 3.67), instant fennel tea (pH = 7.38), whole milk (pH = 6.84) and mineral water (pH = 5.88) were tested. All beverages were given at the same time of day. Salivary pH and buffering capacities of the beverages were determined with a portable pH-meter. Immediately after intake of a beverage, and 5, 10, 15 and 25 minutes later, whole saliva was collected, and the pH-value was measured again. The statistical evaluation was performed using the Wilcoxon test for paired samples. RESULTS: Fifteen children had healthy dentitions. Ten subjects had a mean dmft of 1.1 +/- 2.3. The mean base salivary pH was 7.09 +/- 0.07, without differences between the children with and without dental decay. Mineral water led over the whole period of measurements to a significant rise in salivary pH (P < 0.05). Orange juice caused a significant reduction in the salivary pH during the first 10 minutes. After intake of instant tea or milk, significant reductions were found in the period of 5 to 10 minutes. After the intake of instant tea, the reduction was still significant after 15 minutes. During the period of 5 to 10 minutes, the change in pH (deltapH) in whole saliva differed significantly only between consumption of mineral water and other beverages (P < 0.01). CONCLUSION: With regard to dental health, a regular consumption of orange juice or sweetened instant teas should be discouraged.     

First experience with a public domain computer-aided surgical system

The outcome of complex craniofacial operations is critically dependent on careful and accurate preoperative planning. Recent advances in computer technology enable the surgeon to do surgical simulations directly on to a computer terminal. We describe the clinical application of a public domain-based computer-aided system in craniofacial surgery. Operation planning was based on clinical investigations and radiological images, with particular use of a virtual three-dimensional surgical simulation. Three patients with complex craniofacial malformations were admitted for orbital correction. Surgical simulation defined numerically the extent of bone movements and the extent of resection areas. Operations were guided by the virtual planning. The outcome was compared with the planning to assess the accuracy of the operative correction. Our first experience confirms that computer-assisted simulation is a reliable and useful tool that improves surgical planning and helps to evaluate the surgical outcome.     

Latex allergy and filaggrin null mutations

Objectives

Natural rubber latex (NRL) contains over 200 proteins of which 13 have been identified as allergens and the cause of type I latex allergy. Health care workers share a high occupational risk for developing latex allergy. Filaggrin null mutations increase the risk of type I sensitizations to aeroallergens and it is possible that filaggrin null mutations also increase the risk of latex allergy. The aim of this paper was to examine the association between filaggrin null mutations and type I latex allergy.

Methods

Twenty latex allergic and 24 non-latex allergic dentists and dental assistants, occupationally exposed to latex, were genotyped for filaggrin null mutations R501X and 2282del4. Latex allergy was determined by a positive reaction or a historical positive reaction to a skin prick test with NRL.

Results

41 individuals were successfully genotyped. Three individuals were filaggrin mutation carriers. One (2.4%) was a 2282del4 heterozygote and two (4.9%) were R501X heterozygote. No homozygote or compound heterozygote carriers were detected. No association between filaggrin null mutations and type I latex allergy was found (p = 0.24). Patients with type I latex allergy more often reported contact dermatitis.

Conclusions

This is the first study to examine a highly plausible association between filaggrin null mutations and type I latex allergy. The study subjects were occupationally exposed to latex but no association between latex allergy and filaggrin mutations were detected. Sensitization to latex in the cases in this study may not have occurred through direct skin contact but through the respiratory organs via latex proteins that are absorbed in glove powder and aerosolized.     

Comparison of detrending methods for optimal fMRI preprocessing

Because of the inherently low signal to noise ratio (SNR) of fMRI data, removal of low frequency signal intensity drift is an important preprocessing step, particularly in those brain regions that weakly activate. Two known sources of drift are noise from the MR scanner and aliasing of physiological pulsations. However, the amount and direction of drift is difficult to predict, even between neighboring voxels. Further, there is no concensus on an optimal baseline drift removal algorithm. In this paper, five voxel-based detrending techniques were compared to each other and an auto-detrending algorithm, which automatically selected the optimal method for a given voxel time-series. For a significance level of P < 10(-6), linear and quadratic detrending moderately increased the percentage of activated voxels. Cubic detrending decreased activation, while a wavelet approach increased or decreased activation, depending on the dataset. Spline detrending was the best single algorithm. However, auto-detrending (selecting the best algorithm or none, if detrending is not useful) appears to be the most judicious choice, particularly for analyzing fMRI data with weak activations in the presence of baseline drift.     

Phenotype of mice with inducible ablation of GluA1 AMPA receptors during late adolescence: Relevance for mental disorders

Adolescence is characterized by important molecular and anatomical changes with relevance for the maturation of brain circuitry and cognitive function. This time period is of critical importance in the emergence of several neuropsychiatric disorders accompanied by cognitive impairment, such as affective disorders and schizophrenia. The molecular mechanisms underlying these changes at neuronal level during this specific developmental stage remains however poorly understood. GluA1‐containing AMPA receptors, which are located predominantly on hippocampal neurons, are the primary molecular determinants of synaptic plasticity. We investigated here the consequences of the inducible deletion of GluA1 AMPA receptors in glutamatergic neurons during late adolescence. We generated mutant mice with a tamoxifen‐inducible deletion of GluA1 under the control of the CamKII promoter for temporally and spatially restricted gene manipulation. GluA1 ablation during late adolescence induced cognitive impairments, but also marked hyperlocomotion and sensorimotor gating deficits. Unlike the global genetic deletion of GluA1, inducible GluA1 ablation during late adolescence resulted in normal sociability. Deletion of GluA1 induced redistribution of GluA2 subunits, suggesting AMPA receptor trafficking deficits. Mutant animals showed increased hippocampal NMDA receptor expression and no change in striatal dopamine concentration. Our data provide new insight into the role of deficient AMPA receptors specifically during late adolescence in inducing several cognitive and behavioral alterations with possible relevance for neuropsychiatric disorders. © 2013 Wiley Periodicals, Inc.