The role of retinoids and protein kinase C in vascular smooth muscle cell proliferation and function

The structural and functional changes in the arterial wall of humans and animals accompany the development of hypertension and atherosclerosis. Hence, great interest exists in the mechanisms that govern vascular smooth muscle cell contraction and proliferation. Rat aortic rings maintained in organ culture show a significant loss of contractility; whereas, vascular smooth muscle cells in culture quickly dedifferentiate into a secretory phenotype with a marked capacity for proliferation. The addition of all-trans retinoic acid (RA) and retinol to the plasma-containing medium preserved the contractile response of cultured vessels. Removal of endothelium prior to culture abolished these effects. All-trans retinoic acid but not retinol inhibited A7r5 smooth muscle cell growth; whereas, retinol significantly inhibited A7r5 cell growth in the presence of bovine aortic endothelial cells (BAEC). Conditioned medium from BAEC treated with retinol also inhibited A7r5 cell growth and several metabolites of retinol were found released by BAEC in HPLC analysis. A7r5 smooth muscle cells express five PKC isozymes. RA treatment increased the expression of PKCα, δ, and ε. Overexpression of PKCα in A7r5 cells was used to elucidate its role in the regulation of smooth muscle cell differentiation. Overexpressing clones had altered morphology and decreased growth rates. Cell differentiation marker proteins such as vinculin and desmin were not affected by PKCα overexpression; whereas, the expression of smooth muscle-specific a-actin was markedly reduced. These findings suggest that PKCα may regulate growth independently from differentiation. The results suggest that circulating factors, such as retinol and retinoic acid, may be necessary for the maintenance of the differentiated state of smooth muscle. Retinol appears to exert its effects primarily on the endothelium, which in turn secretes stable factors that affect smooth muscle phenotype. The regulatory effect of RA may involve PKC. Individual isoforms of PKC may play different roles in regulating smooth muscle cell proliferation and contraction

A SiO J = 5 - 4 Survey Toward Massive Star Formation Regions

We performed a survey in the SiO $J=5\rightarrow4$ line toward a sample of 199 Galactic massive star-forming regions at different evolutionary stages with the SMT 10 m and CSO 10.4 m telescopes. The sample consists of 44 infrared dark clouds (IRDCs), 86 protostellar candidates, and 69 young \HII\ regions. We detected SiO $J=5\rightarrow4$ line emission in 102 sources, with a detection rate of 57\%, 37\%, and 65\% for IRDCs, protostellar candidates, and young \HII\ regions, respectively. We find both broad line with Full Widths at Zero Power (FWZP) $>$ 20 \kms and narrow line emissons of SiO in objects at various evolutionary stages, likely associated with high-velocity shocks and low-velocity shocks, respectively. The SiO luminosities do not show apparent differences among various evolutionary stages in our sample. We find no correlation between the SiO abundance and the luminosity-to-mass ratio, indicating that the SiO abundance does not vary significantly in regions at different evolutionary stages of star formation.Comment: 25 pages, 9 figures, 5 tables, accepted for publication in Ap

Rapid progression of subcutaneous glioblastoma: A case report and literature review

Extra-neural spread of glioblastoma (GBM) is extremely rare. We report a case of postoperative intracranial GBM spreading to the subcutaneous tissue via the channel of craniotomy defect in a 73-year-old woman. Radiological images and histopathology indicate that the tumor microenvironment of the subcutaneous tumor is clearly different from the intracranial tumor. We also model the invasion of GBM cells through the dura-skull defect in mouse. The retrospective analysis of GBM with scalp metastases suggests that craniectomy is a direct cause of subcutaneous metastasis in patients with GBM. Imaging examinations of other sites for systemic screening is also recommended to look for metastases outside the brain when GBM invades the scalp or metastasizes to it

Effects of Ca addition on the uptake, translocation, and distribution of Cd in Arabidopsis thaliana

Cadmium (Cd) pollution poses a risk to human health for its accumulation in soil and crops, but this can be alleviated by calcium (Ca) addition. However, its mechanism remains unclear yet. In this study, Arabidopsis thaliana was used to explore the alleviating effects of Ca on Cd toxicity and its specific function during uptake, upward-translocation, and distribution of Cd. Supplementing plants with 5 mM CaCl2 alleviated the intoxication symptoms caused by 50 μM CdCl2, such as smaller leaves, early bolting and root browning. Ca addition decreased uptake of Cd, possibly by reducing the physical adsorption of Cd since the root cell membrane was well maintained and lignin deposition was decreased as well, and by decreasing symplastic Cd transport. Expression of the genes involved (AtZIP2 and AtZIP4) was also decreased. In addition, Ca accumulated in the plant shoot to help facilitating the upward-translocation of Cd, with evidence of higher translocation factor and expression of genes that were involved in Ca transport (AtPCR1) and Cd xylem loading (AtHMA2 and AtHMA4). Dithizone-staining of Cd in leaves showed that in Cd+Ca-treated plants, Ca addition initially protected the leaf stomata by preventing Cd from entering guard cells, but with prolonged Cd treatment facilitated the Cd accumulation around trichomes and maybe its excretion. We conclude that Ca promotes the upward-translocation of Cd and changes its distribution in leaves. The results may have relevance for bioremediation

Isolation of Potential Photosynthetic N\u3csub\u3e2\u3c/sub\u3e-Fixing Microbes from Topsoil of Native Grasslands in South Dakota

Nitrogen fertilizer is one of the most limiting factors and costly inputs in agriculture production. Current fossil fuel-dependent ammonia production is both energy intensive and environmentally damaging. An economically practical and environmentally friendly solution for the production of ammonia is urgently needed. Solar-powered N2-fixing cyanobacteria provide a unique opportunity and promise for applications in agriculture compared to all other N2-fixing bacteria that cannot use solar energy. Isolation of nitrogen-fixing microbes from the topsoil of native grasslands may have the potential to use them in crop fields as living ammonia factories. This may be a mechanism to free farmers from heavy reliance on fossil fuels-dependent chemical nitrogen fertilizers and to improve soil health for sustainable agriculture. To screen for solar-powered N2-fixing cyanobacteria in topsoil of native grasslands in South Dakota, we collected 144 topsoil samples from several native grasslands. Six photosynthetic microbial strains were isolated that are capable of growing well autotrophically in a nitrogen-free medium, suggesting that these six microbial strains have the ability to fix N2. They were assigned the names: Xu15, Xu81, Xu86, Xu111, Xu141, and WW3. Based on cell morphology and its 18S rRNA gene sequence that we obtained, strain Xu15 was reassigned as Chloroidium saccharophilum Xu15, a common terrestrial coccoid green alga. An acetylene reduction assay detected substantial ethylene production, suggesting nitrogenase activity occurrences in cultures Xu81 and Xu15. The other four are in the process of purification for testing their nitrogenase activity. Xu81, Xu111 and Xu141 are probably unicellular microalga, while WW3 and Xu86 are likely filamentous cyanobacteria. Future research will focus on developing these validated N2-fixing microbes as in situ living ammonia factories in crop fields