湖南株洲晚白垩世恐龙化石的初步研究

我国南方上白垩统产丰富的恐龙蛋化石,但发现的恐龙骨骼化石的种类和数量相对较少。本文对湖南株洲天元区新发现的恐龙化石进行详细研究。初步分析结果表明该化石点恐龙种类丰富,可能包括至少两种蜥脚类、三种兽脚类和一种鸭嘴龙类。其中部分蜥脚类材料可能归属于梁龙超科,填补了该类群在东亚上白垩统的空白记录;一个蜥脚类坐骨则显示泰坦巨龙类的典型特征。兽脚类材料可能来自于小型的虚骨龙类、暴龙科和鲨齿龙科。前两者为晚白垩世的常见类群,而鲨齿龙科的化石记录在上白垩统非常少见。本文为鲨齿龙科可能在东亚一直延伸至晚白垩世提供了新的证据。该地区多门类恐龙化石的发现表明我国南方恐龙的种类可能比我们想象的要丰富得多,而且可能是梁龙类和鲨齿龙类的最后栖息地。株洲恐龙动物群的发现对于了解亚洲特别是中国恐龙的生物地理区系的分布具有重要意义。     

Characterization and modulation of human mesenchymal stem cell stress pathway response following hypothermic storage

Human mesenchymal stem cell (hMSC) research has grown exponentially in the last decade. The ability to process and preserve these cells is vital to their use in stem cell therapy. As such, understanding the complex, molecular-based stress responses associated with biopreservation is necessary to improve outcomes and maintain the unique stem cell properties specific to hMSC. In this study hMSC were exposed to cold storage (4 °C) for varying intervals in three different media. The addition of resveratrol or salubrinal was studied to determine if either could improve cell tolerance to cold. A rapid elevation in apoptosis at 1 h post-storage as well as increased levels of necrosis through the 24 h of recovery was noted in samples. The addition of resveratrol resulted in significant improvements to hMSC survival while the addition of salubrinal revealed a differential response based on the media utilized. Decreases in both apoptosis and necrosis together with decreased cell stress/death signaling protein levels were observed following modulation. Further, ER stress and subsequent unfolded protein response (UPR) stress pathway activation was implicated in response to hMSC hypothermic storage. This study is an important first step in understanding hMSC stress responses to cold exposure and demonstrates the impact of targeted molecular modulation of specific stress pathways on cold tolerance thereby yielding improved outcomes. Continued research is necessary to further elucidate the molecular mechanisms involved in hypothermic-induced hMSC cell death. This study has demonstrated the potential for improving hMSC processing and storage through targeting select cell stress pathways.     

Comparison of Media for Isolation of Salmonellae and Shigellae from Fecal Specimens

Five transport media, eight plating media, and three enrichment broth media for the isolation of salmonellae and shigellae were evaluated. Eight laboratories in widely separated regions of the United States participated in this evaluation by submitting 490 fecal specimens in the transport media provided. The results suggest that the newer transport media may not offer any advantage over the use of buffered glycerol-saline in the isolation of these enteric pathogens. Shigellae were best isolated by direct inoculation, whereas salmonellae were isolated in greater numbers after tetrathionate (without Brilliant Green) enrichment with subsequent culturing on the plating medium. The use of a variety of plating media is recommended for the recovery of a larger number of these enteric pathogens.     

Recruitment of exogenous macrophages into metastases at different stages of tumor growth

Summary The endogenous tumor-associated macrophage content and recruitment of labeled peritoneal exudate cells into experimental murine B16 melanoma metastases has been examined at different stages in the progressive growth of metastatic lesions. The recruitment of thioglycollate-elicited peritoneal exudate cells and peritoneal exudate cells activated in vitro with muramyl dipeptide was studied. Tumor-associated macrophages and labeled peritoneal exudate cells were identified in paraffin sections by specific histochemical staining and their density in individual metastases measured morphometrically. The density of tumor-associated macrophages and exogenously recruited peritoneal exudate cells was high in very small lesions but decreased rapidly as a function of enlargement of metastases, MD:Aⁿ; where MD is macrophage density, A is the cross-sectional area of the lesion and n is a negative number. No significant difference was observed in the recruitment of activated and nonactivated peritoneal exudate cells. These results suggest that decreased recrutiment of macrophages from the circulation may explain the decrease in the density of tumor-associated macrophages as metastases grow and indicate that macrophage activation is not accompanied by enhanced localization and/or uptake of macrophages into metastases.     

The role of hydrophobic properties of chemicals in promoting allosteric reactions

An allosteric reaction has been found in a variety of instances where an inverted parabolic relationship between biological activity and hydrophobicity is apparent, that is the activity first decreases as hydrophobicity increases and after a certain point, activity begins to increase. This could be attributed to the ligands causing a change in the receptor structure. In this report, the role of hydrophobic properties of chemicals in promoting allosteric reactions have been discussed in term of hydrophobicity (logP) by the formulation of a total number of 50 QSAR equations. The QSAR model of this type may be represented by Eq. I.     

A comparison between two polarizability parameters in chemical--biological interactions

The polarizability of a molecule, an important physical property, is currently attracting our attention particularly in the area of QSAR (quantitative structure-activity relationships) for chemical-biological interactions. Our primary focus in the present study has been upon the computational aspects by using NVE (sum of the valence electrons) as a means for estimating polarizability, we have been surprised at its utility. In this report we demonstrate how NVE can be related to the calculated polarizability from a variety of efforts to better understand the subject. A comparison between the use of two polarizability parameters, that is, NVE and CMR (calculated molar refractivity) in the formulation of QSAR for chemical-biological interactions has been also discussed.     

Two Early Cretaceous Fossils Document Transitional Stages in Alvarezsaurian Dinosaur Evolution

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Structure-Activity Relationship in the Auxin Activity of Mono-Substituted Phenylacetic Acids

The analysis of substituent constants for the lipophilic and electronic factors in the auxin activity of substituted phenylacetic acids in elongation of coleoptile segments shows that these factors parallel those for the phenoxyacetic acids but assign reactivity in growth promotion to the meta position of phenylacetic acid. The inhibitory effects with supra-optimal concentrations are highly dependent on the lipophilic character of the molecules.     

Detection of circulating Dirofilaria immitis antigens in random source laboratory dogs: evaluation of two commercial serodiagnostic tests

Two commercially available serodiagnostic tests for Dirofilaria immitis antigens were evaluated for sensitivity, specificity, predictive values, and reliability using serum from 110 random source dogs. Both tests were performed in two separate laboratories on serum samples randomized in five blocks of 22 samples each. Dogs were examined for microfilariae using the modified Knott's technique, and for adult parasites by necropsy. Forty-eight of the 110 dogs (43.6%) had either adult or juvenile parasites within the cardiopulmonary vasculature or microfilariae in the peripheral blood. Of those 48, 26 (54.2%) were amicrofilaremic and had cardiopulmonary parasite populations ranging from one to greater than 50. In both laboratories, both commercial tests failed to detect infection in eight of the 26 amicrofilaremic dogs. Three amicrofilaremic dogs were positive by both tests in both laboratories. Four dogs (3.6%) had microfilariae without adults. Two of those four dogs were negative by both commercial tests in both laboratories. One commercial test had 38 false negatives in one laboratory, 13 of which were also negative in the second laboratory. The other test had 21 false negatives in one laboratory and 20 in the other laboratory. Fourteen of these samples were falsely negative in both laboratories. False positives were low in both laboratories for both tests.