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71.
Heiden TC Haines AN Manire C Lombardi J Koob TJ 《Journal of experimental zoology. Part A, Comparative experimental biology》2005,303(7):577-589
In the viviparous bonnethead shark, Sphyrna tiburo, a fluid-filled, acellular egg capsule surrounds fertilized eggs and developing embryos throughout gestation. Like other placental shark species, the capsule remains intact even at the placental implantation site. Although its intervention between the uterine and embryonic tissues of the placenta has long been thought to mediate physiological exchange, little information is available concerning even its basic structure or permeability to solutes. The 1 mum thick capsule wall consists of an inner layer of gelatinous material and an outer layer consisting of at least three laminae of orthogonally arranged fibrous material. These fibers are irregular and often branched. Permeability experiments showed that solutes less than 1,355 Da diffuse across the egg capsule whereas those greater than 6,000 Da do not pass through the membrane. Solute movement across the capsule is a concentration-dependent phenomenon indicating diffusion rather than active transport. Experimental data also suggest that there is an increase in the permeability of the egg capsule to low molecular weight materials during mid- and late gestation. These observations are discussed in relation to the function of the egg capsule as a mediator of maternal-embryonic interactions in matrotrophic sharks. 相似文献
72.
73.
Ashley Erin Clark 《The Yale journal of biology and medicine》2012,85(3):421-424
Now in its 8th year, the Yale Healthcare Conference has arguably come upon its
most exciting and dramatic time within the U.S. health care system. Dynamic
speakers from all over the country came together in April 2012 at Yale
University to question, debate, creatively think, and examine challenges within
health care organizations and institutions. One of the most prominent issues
concerned the aftermath of sequencing the human genome and the explosion of
information concerning gene polymorphisms and biomarkers in health and disease.
Clinicians, scientists, and pharmaceuticals are looking to innovative
individually tailored treatments for patients. During the conference breakout
session, speakers Thomas Lynch, MD, director of the Yale Cancer Center and
physician-in-chief of the Smilow Cancer Hospital, and Zen Chu, MBA, co-founder
of Accelerated Medical Ventures and entrepreneur-in-residence at Massachusetts
Institute of Technology, provided enriching discussion on the delivery of
science and genetic care of the individual. 相似文献
74.
Huang Xudong Atwood Craig S. Moir Robert D. Hartshorn Mariana A. Tanzi Rudolph E. Bush Ashley I. 《Journal of biological inorganic chemistry》2004,9(8):954-960
Nucleation-dependent protein aggregation (seeding) and amyloid fibril-free formation of soluble SDS-resistant oligomers (oligomerization) by hydrophobic interaction is an in vitro model thought to propagate -amyloid (A) deposition, accumulation, and incur neurotoxicity and synaptotoxicity in Alzheimers disease (AD), and other amyloid-associated neurodegenerative diseases. However, A is a high-affinity metalloprotein that aggregates in the presence of biometals (zinc, copper, and iron), and neocortical A deposition is abolished by genetic ablation of synaptic zinc in transgenic mice. We now present in vitro evidence that trace (0.8 µM) levels of zinc, copper, and iron, present as common contaminants of laboratory buffers and culture media, are the actual initiators of the classic A1–42-mediated seeding process and A oligomerization. Replicating the experimental conditions of earlier workers, we found that the in vitro precipitation and amyloidosis of A1–40 (20 µM) initiated by A1–42 (2 µM) were abolished by chelation of trace metal contaminants. Further, metal chelation attenuated formation of soluble A oligomers from a cell-free culture medium. These data suggest that protein self-assembly and oligomerization are not spontaneous in this system as previously thought, and that there may be an obligatory role for metal ions in initiating A amyloidosis and oligomerization. 相似文献
75.
Staphylococcus aureus is a major cause of antimicrobial-resistant infections of humans. Hybrids of S. aureus, which originate from large-scale chromosomal recombinations between parents of distinct genetic backgrounds, are of interest from clinical and evolutionary perspectives. We present draft genome sequences of two S. aureus hybrids of sequence type 34 (ST34) and ST42. 相似文献
76.
JS Gilbert CT Banek AJ Bauer A Gingery HC Dreyer 《American journal of physiology. Regulatory, integrative and comparative physiology》2012,303(5):R520-R526
Although exercise during pregnancy is generally recommended and thought to be beneficial to mother and fetus, the nature of the adaptations to exercise during pregnancy and how they may be beneficial remain poorly understood. Recent studies suggest that exercise may stimulate expression of several cytoprotective and pro-angiogenic molecules such as heat shock proteins (HSP) and vascular endothelial growth factors (VEGF). We hypothesized that exercise training during pregnancy improves angiogenic balance, increases HSP expression, and improves endothelial function. Female rats were given access to an exercise wheel for 6 wk before and during pregnancy. On day 19 of pregnancy tissues were collected and snap frozen for later analysis. Western blots were performed in skeletal muscle and placenta. HSP 27 (3.7 ± 0.36 vs. 2.2 ± 0.38; P < 0.05), HSP 60 (2.2 ± 0.73 vs. 0.49 ± 0.08; P < 0.05), and HSP 90 (0.33 ± 0.09 vs. 0.11 ± 0.02; P < 0.05) were increased in the placentas of exercise-trained rats compared with sedentary controls. In addition, exercise training increased (P < 0.05) plasma free VEGF and augmented (P < 0.05) endothelium-dependent vascular relaxation compared with nonexercise control rats. The present data indicates chronic exercise training stimulates HSP expression in the placenta and that regular exercise training increases circulating VEGF in pregnant but not in nonpregnant rats. Although the present findings suggest that exercise before and during pregnancy may promote the expression of molecules that could attenuate placental and vascular dysfunction in complicated pregnancies, further studies are needed to determine the safety and effectiveness of exercise training as a therapeutic modality in pregnancy. 相似文献
77.
78.
Yi‐Jun Qi Douglas G. Ward Chun Pang Qi‐Ming Wang Wenbin Wei Jin Ma Juan Zhang Qiang Lou Neil J. Shimwell Ashley Martin Nathalie Wong Wei‐Xia Chao Ming Wang Yuan‐Fang Ma Philip J. Johnson 《Proteomics》2014,14(2-3):186-195
The aim of this study was to identify novel biomarkers for the diagnosis of, and potential therapeutic targets for, hepatocellular carcinoma (HCC). Multilectin affinity chromatography was used to enrich N‐linked glycoproteins from nontumorous liver and HCC tissues followed by 2DE and protein identification by MS. Twenty‐eight differentially expressed proteins were identified. Western blotting validated consistently lower concentrations of human liver carboxylesterase 1 and haptoglobin, and higher concentration of procathepsin D (pCD) in HCC tissues. Knockdown of cathepsin D (CD) expression mediated by siRNA significantly inhibited the in vitro invasion of two HCC cell lines, SNU449 and SNU473, which normally secrete high‐levels of CD. Prefractionation using individual lectins demonstrated an elevation in ConA‐binding glycoforms of proCD and CD in HCC tissues. In the serum of HCC patients, “ConA‐binding proCD” (ConA‐pCD) is significantly increased in concentration and this increase is comprised of several distinct upregulated acidic isoforms (pI 4.5–5.5). Receiver operating characteristic analysis showed that the sensitivity and specificity of serum ConA‐pCD for HCC diagnosis were 85% and 80%, respectively. This is the first report that serum ConA‐pCD is increased significantly in HCC and is potentially useful as a serological biomarker for diagnosis of HCC. 相似文献
79.
80.
Jennifer D. Watts Mary Farina John S. Kimball Luke D. Schiferl Zhihua Liu Kyle A. Arndt Donatella Zona Ashley Ballantyne Eugénie S. Euskirchen Frans-Jan W. Parmentier Manuel Helbig Oliver Sonnentag Torbern Tagesson Janne Rinne Hiroki Ikawa Masahito Ueyama Hideki Kobayashi Torsten Sachs Daniel F. Nadeau John Kochendorfer Marcin Jackowicz-Korczynski Anna Virkkala Mika Aurela Roisin Commane Brendan Byrne Leah Birch Matthew S. Johnson Nima Madani Brendan Rogers Jinyang Du Arthur Endsley Kathleen Savage Ben Poulter Zhen Zhang Lori M. Bruhwiler Charles E. Miller Scott Goetz Walter C. Oechel 《Global Change Biology》2023,29(7):1870-1889
Arctic-boreal landscapes are experiencing profound warming, along with changes in ecosystem moisture status and disturbance from fire. This region is of global importance in terms of carbon feedbacks to climate, yet the sign (sink or source) and magnitude of the Arctic-boreal carbon budget within recent years remains highly uncertain. Here, we provide new estimates of recent (2003–2015) vegetation gross primary productivity (GPP), ecosystem respiration (Reco), net ecosystem CO2 exchange (NEE; Reco − GPP), and terrestrial methane (CH4) emissions for the Arctic-boreal zone using a satellite data-driven process-model for northern ecosystems (TCFM-Arctic), calibrated and evaluated using measurements from >60 tower eddy covariance (EC) sites. We used TCFM-Arctic to obtain daily 1-km2 flux estimates and annual carbon budgets for the pan-Arctic-boreal region. Across the domain, the model indicated an overall average NEE sink of −850 Tg CO2-C year−1. Eurasian boreal zones, especially those in Siberia, contributed to a majority of the net sink. In contrast, the tundra biome was relatively carbon neutral (ranging from small sink to source). Regional CH4 emissions from tundra and boreal wetlands (not accounting for aquatic CH4) were estimated at 35 Tg CH4-C year−1. Accounting for additional emissions from open water aquatic bodies and from fire, using available estimates from the literature, reduced the total regional NEE sink by 21% and shifted many far northern tundra landscapes, and some boreal forests, to a net carbon source. This assessment, based on in situ observations and models, improves our understanding of the high-latitude carbon status and also indicates a continued need for integrated site-to-regional assessments to monitor the vulnerability of these ecosystems to climate change. 相似文献