Primary hyperparathyroidism is associated with increased circulating bone marrow-derived progenitor cells

Recently, parathyroid hormone (PTH) was shown to support survival of progenitor cells in bone marrow. The release of progenitor cells occurs in physiological and pathological conditions and was shown to contribute to neovascularization in tumors and ischemic tissues. In the present study we sought to investigate prospectively the effect of primary hyperparathyroidism (PHPT) on mobilization of bone marrow-derived progenitor cells. In 22 patients with PHPT and 10 controls, defined subpopulations of circulating bone marrow-derived progenitor cells (BMCs) were analyzed by flow cytometry (CD45(+)/CD34(+)/CD31(+) cells indicating endothelial progenitor cells, CD45(+)/CD34(+)/c-kit(+) cells indicating hematopoietic stem cells, and CD45(+)/CD34(+)/CXCR4(+) cells indicating progenitor cells with the homing receptor CXCR4). Cytokine serum levels (SCF, SDF-1, VEGF, EPO, and G-CSF) were assessed using ELISA. Levels of PTH and thyroid hormone as well as serum electrolytes, renal and liver parameters, and blood count were analyzed. Our data show for the first time a significant increase of circulating BMCs and an upregulation of SDF-1 and VEGF serum levels in patients with PHPT. The number of circulating BMCs returned to control levels measured 16.7 +/- 2.3 mo after surgery. There was a positive correlation of PTH levels with the number of CD45(+)/CD34(+)/CD31(+), CD45(+)/CD34(+)/c-kit(+), and CD45(+)/CD34(+)/CXCR4(+) cells. However, there was no correlation between cytokine serum concentrations (SDF-1, VEGF) and circulating BMCs. Serum levels of G-CSF, EPO, and SCF known to mobilize BMCs were even decreased or remained unchanged, suggesting a direct effect of PTH on stem cell mobilization. Our data suggest a new function of PTH mobilizing BMCs into peripheral blood.     

DNA Sequence Explains Seemingly Disordered Methylation Levels in Partially Methylated Domains of Mammalian Genomes

For the most part metazoan genomes are highly methylated and harbor only small regions with low or absent methylation. In contrast, partially methylated domains (PMDs), recently discovered in a variety of cell lines and tissues, do not fit this paradigm as they show partial methylation for large portions (20%–40%) of the genome. While in PMDs methylation levels are reduced on average, we found that at single CpG resolution, they show extensive variability along the genome outside of CpG islands and DNase I hypersensitive sites (DHS). Methylation levels range from 0% to 100% in a roughly uniform fashion with only little similarity between neighboring CpGs. A comparison of various PMD-containing methylomes showed that these seemingly disordered states of methylation are strongly conserved across cell types for virtually every PMD. Comparative sequence analysis suggests that DNA sequence is a major determinant of these methylation states. This is further substantiated by a purely sequence based model which can predict 31% (R²) of the variation in methylation. The model revealed CpG density as the main driving feature promoting methylation, opposite to what has been shown for CpG islands, followed by various dinucleotides immediately flanking the CpG and a minor contribution from sequence preferences reflecting nucleosome positioning. Taken together we provide a reinterpretation for the nucleotide-specific methylation levels observed in PMDs, demonstrate their conservation across tissues and suggest that they are mainly determined by specific DNA sequence features.     

Lamins as mediators of oxidative stress

The nuclear lamina defines both structural and functional properties of the eukaryotic cell nucleus. Mutations in the LMNA gene, encoding A-type lamins, lead to a broad spectrum of diseases termed laminopathies. While different hypotheses have been postulated to explain disease development, there is still no unified view on the mechanistic basis of laminopathies. Recent observations indicate that laminopathies are often accompanied by altered levels of reactive oxygen species and a higher susceptibility to oxidative stress at the cellular level. In this review, we highlight the role of reactive oxygen species for cell function and disease development in the context of laminopathies and present a framework of non-exclusive mechanisms to explain the reciprocal interactions between a dysfunctional lamina and altered redox homeostasis.     

Uniconazole inhibits stress-induced ethylene in wheat and soybean seedlings

Previous studies have shown that uniconazole inhibits ethylene synthesis and protects plants from various stresses. The present research was conducted to delineate the mechanism of ethylene inhibition by uniconazole [(E)-(p-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten-3-ol]. Following heat stress of 48°C for 3 h, the shoots of the control wheat seedlings became desiccated, and the seedlings lost 23% of their fresh mass 8 h after stress. The control soybean seedlings had epinastic unifoliate leaves 5 h after foliar application (4.4 g.a.i./ha) of the herbicide triclopyr [(3,5,6-trichloro-2-pyridinyl)oxyacetic acid]. Soil drench applications of uniconazole, a potent member of the triazole family, reduced these symptoms associated with heat and herbicide stress in wheat (5.0 mg/L) and soybean (0.4 mg/L) seedlings, respectively. Basal ethylene production was inhibited 32 and 48% by uniconazole in the wheat and acotyledonous soybean seedlings, respectively. Following a 48°C heat stress, 1-aminocyclopropane-1-carboxylic acid (ACC) levels increased 40% in both the control and uniconazole-treated wheat seedlings. After triclopyr application, ACC levels increased 400% in both the control and uniconazoletreated soybean seedlings. The increased ACC levels, following stress, were accompanied by increased ethylene production from the control, but not from the uniconazole-treated wheat and acotyledonous soybean seedlings. Uniconazole treatment did not significantly change the basal or stress-induced N-malonyl-1-aminocyclopropane-1-carboxylic acid (MACC) levels compared to controls. These results suggest that uniconazole inhibits ethylene synthesis by interfering with the conversion of ACC to ethylene in wheat and acotyledonous soybean seedlings. Ethylene production and ACC conversion were not inhibited by uniconazole in excised soybean cotyledons. These results indicate that different ethylene-forming enzyme (EFE) systems operate in the soybean acotyledonous seedling and cotyledon, and the system in the former is inhibited by uniconazole.     

The rodent estrous cycle: characterization of vaginal cytology and its utility in toxicological studies

While an evaluation of the estrous cycle in laboratory rodents can be a useful measure of the integrity of the hypothalamic-pituitary-ovarian reproductive axis, it can also serve as a way of insuring that animals exhibiting abnormal cycling patterns are disincluded from a study prior to exposure to a test compound. Assessment of vaginal cytology in regularly cycling animals also provides a means to establish a comparable endocrine milieu for animals at necropsy. The procedure for obtaining a vaginal smear is relatively non-invasive and is one to which animals can become readily accustomed. It requires few supplies, and with some experience the assessments can be easily performed in fresh, unstained smears, or in fixed, stained ones. When incorporated as an adjunct to other endpoint measures, a determination of a female's cycling status can contribute important information about the nature of a toxicant insult to the reproductive system. In doing so, it can help to integrate the data into a more comprehensive mechanistic portrait of the effect, and in terms of risk assessment, may provide some indication of a toxicant's impact on human reproductive physiology.