Recombination between homologous chromosomes does not play a dominant role in the formation of radiation-induced chromosomal aberrations

Purpose : In mammalian cells, the relevance of homologous recombination in radiation-induced double-strand break (DSB) repair is not yet well understood. In the present work, the role of recombination between homologous chromosomes and homology-directed repair of DSB were studied, using X-ray-induced chromosomal aberrations as an end-point. Materials and methods : Human-hamster hybrid cells containing one or two copies of human chromosome 8 were used. If recombination between homologous chromosomes plays a dominant role in DSB repair, it is expected that X-irradiation of cells with two copies of chromosome 8 would result in a lower frequency of aberrations involving this chromosome compared with cells with only one copy of chromosome 8. The aberrations involving human chromosome 8 were detected by fluorescence in situ hybridization (FISH). Furthermore, a comparison between the hamster cell line XR-C1 (defective in non-homologous repair), CHO-9 (the wild-type cells) and the cell line XR-C1#8 (in which the defect of XR-C1 is complemented by human chromosome 8) was made to determine, indirectly, the involvement of homology-directed recombination in DSB repair. Results : The observed frequencies of aberrations per human chromosome 8 were not significantly different between cells containing one or two copies of this chromosome. The frequency of chromatid-type aberrations was doubled in XR-C1 cells compared with CHO-9 and XR-C1#8 cells. Conclusions : In hamster cells, recombination between homologous chromosomes appears not to have a major role in the formation of radiation-induced chromosomal aberrations, while nonhomologous repair seems to be important in both the G1 and G2 phases of the cell cycle.     

Wirkung von Diclofenac auf humane Osteoblasten und stromale Knochenmarkzellen in vitro in bezug auf die Endoprothetik

INTRODUCTION: Results of animal experiments have demonstrated that the osseous integration of non-cemented prostheses can, at the very least temporarily, be impaired by the application of non-steroidal antiphlogistic agents (such as diclofenac). It is the objective of this study to examine whether there is a direct influence of diclofenac used in usual clinical dosages (3 times 50 mg daily) on bone cells and their progenitor cells which would explain the observed slow integration of the prostheses. METHODS: To investigate this, cultivated human in vitro osteoblasts and stromal bone marrow cells were incubated with increasing doses of the medications. Our study focused on the effect of diclofenac application on proliferation and functional metabolism in both cell lines. The measurable maximal plasma concentration 2 h after the application of one tablet Voltaren 50 reached 1.6 micrograms/ml. This correlated with diclofenac concentrations between 1 and 10 ml found in our experiments. The detected values were correlated to the control group (0 microgram/ml diclofenac). RESULTS: The drug effect upon osteoblasts was higher than on progenitor cells. The proliferation of in vitro stromal bone marrow cells, compared to untreated cells, was found to be decreased. We observed a decrease to 82% at a diclofenac concentration of 1 microgram/ml, Osteoblasts exhibited a decrease to 97.5% at the same concentration. The DNA synthesis increased to 118% in stromal bone marrow cells, in osteoblasts to 144%. In contrast, we detected a neglectible decrease to 92% in the collagen synthesis of osteoblasts compared to untreated cells. The synthesis of osteocalcin by osteoblasts increased to 119%. The alkaline phosphatase activity was found to be decreased to 88% in stromal bone marrow cells and increased in osteoblasts to 111%. CONCLUSION: Temporary inhibiting effects on osseous integration in non-cemented prosthesis by diclofenac could be caused by a disturbance in the anabolic bone metabolism, exhibited by an increase of osteoblastic osteocalcin expression. Osteocalcin as a known negative regulator of the osteoneogenesis is most likely inhibiting the collagen matrix deposition.     

Anatomical Variation in Maxillary Sinus Ostium Positioning: Implications for Nasal-Sinus Disease

Among humans, superiorly located maxillary sinus ostia (MSO) result in drainage complications and maxillary sinus (MS) disease. While previous studies investigate maxillary sinusitis frequency or MSO-position relative to specific nasal landmarks, few explore MSO-position to overall MS dimensions. This study investigates whether MSO-position relates to MS size/shape and if sex-based differences exist. Twenty-nine landmarks, placed on magnetic resonance images (MRIs) of 109 individuals (males = 57; females = 52), captured maximum dimensions of the cranium, MS, nasal cavity, and MSO-position relative to the MS floor (MSO_MSF) and nasal floor (MSO_NCF). Landmark coordinates were used to calculate centroid sizes and 13 linear distances; distances were size standardized by cranial centroid-size. Principal components analysis (PCA) on 3D-coordinates indicates that variation in MSO-position relates to superior–inferior MS positioning within the face (PC1 22% variance) and MS height (PC2 12% variance). Regression analyses indicate that MS size (r² = 0.502; P < 0.001) and height (r² = 0.589; P < 0.0001) strongly contribute to MSO_MSF: larger, taller MSs exhibit greater MSO_MSFs. Sex-based differences were not evident in PC shape-analyses nor among size-standardized dimensions. However, Mann–Whitney U-tests indicate females have absolutely smaller MSs (P = 0.001) and MSO_MSF distances (P = 0.001). Further, regressions indicate females exhibit lower MSO_MSFs for a similar MS height. Overall, MSOs superiorly placed relative to the MS floor correlate with larger, taller MSs and/or sinuses positioned inferiorly within the face. While craniofacial surgeons/clinicians should be aware of potential sex-based differences in MS size and MSO position, this study does not suggest that higher incidences of female-reported sinusitis relate to sex-based differences in MS anatomy. Anat Rec, 302:917–930, 2019. © 2018 Wiley Periodicals, Inc.     

Conductor Compounds of Phenylpentane in Mycoleptodonoides aitchisonii Mycelium Enhance the Release of Dopamine from Rat Brain Striatum Slices

Abstract

Monoterpene compound is a major component of essential oils in various aromatic species. Previous reports about the monoterpene compound linalool and its effect on the brain neurotransmitters glutamic acid, GABA and acetylcholine, but not catecholamines, have been reported. In this study, we investigated the effect of linalool or conductor compounds of phenylpentane, including 1-phenyl-3-pentanol and 1-phenyl-3-pentanone, on dopamine release using rat striatal slices. The edible mushroom Mycoleptodonoides aitchisonii belongs to the Climacodontaceae family, and its cultivate medium or mycelium contains derivatives of the fragrant conductor compound, phenylpentane. Compared to basal levels, 2.5 μg linalool increased dopamine from striatal slices 3-fold. A 4-fold increase in dopamine release resulted from 2.5 μg 1-phenyl-3-pentanol administration, while a half dose of this compound induced a 2.5-fold increase. A greater than 2-fold increase resulted with 2.5 μg 1-phenyl-3-pentanone. These data indicate that striatum has sensitivity for these fragrant compounds and different releasing effects result with differ structures. These actions may affect other neurotransmitters and influence brain function.