Transmembrane Orientation of Hydrophobic α-Helices Is Regulated Both by the Relationship of Helix Length to Bilayer Thickness and by the Cholesterol Concentration†

Biochemistry ◽  
1997 ◽  
Vol 36 (33) ◽  
pp. 10213-10220 ◽  
Author(s):  
Jianhua Ren ◽  
Scott Lew ◽  
Zhiwei Wang ◽  
Erwin London
1998 ◽  
Vol 13 (10) ◽  
pp. 2902-2909 ◽  
Author(s):  
D. Josell ◽  
D. van Heerden ◽  
D. Read ◽  
J. Bonevich ◽  
D. Shechtman

Yield stresses, ultimate tensile strengths, and specific strengths of aluminum/titanium multilayer thin films are determined from the results of uniaxial tensile tests. The plasticity in the stress-strain curves, the nature of the fracture surfaces, and the relationship of the yield stress and the bilayer thickness are discussed. Properties are compared with those of other multilayer materials published in the literature.


2020 ◽  
Author(s):  
zhu chen ◽  
xiaolong Huang ◽  
na Han ◽  
Yanxia Guo ◽  
Jing Chen ◽  
...  

Abstract Background The clinical efficacy of plasmapheresis (PP) in patients with hypertriglyceridemic acute pancreatitis (HLAP) might affected by total cholesterol (TC). The objective of this study is to determine the relationship of TC and the Triglyceride (TG)-lowing effect in patients on either non-PP or PP therapy.MethodsPatients were categorized into high total cholesterol (HTC) /low total cholesterol (LTC) groups based on TC level of 12.4 mmol/l. The primary outcome was TG reduction to below 500mg/dl within 48 hours. Linear mixed-effect model and logistic regression analyses were used to assess the association of TC and different therapy groups on TG-lowing efficacy.ResultsCompared with LTC group, patients with HTC showed more severe imaging manifestations(p<0.001) and higher APACH Ⅱ scores (p=0.036). Deaths occurred only in HTC groups. Significant interaction of time sequence with the 2 TGs-lowing therapy groups on TG level was only found in HTC group (p < 0.001). In patients with elevated TC level, primary outcome occurred in 66.67% of patients in the PP group, and 27.91% in the non-PP group. After adjustment for age, gender, CT grade and APACH II score, the odd ratio remain significant (OR 5.47, 95% confidence interval [CI] 1.84-16.25, p = 0.002). Furthermore, in patients with lower TC level, primary outcome occurred in 81.25% of patients in the PP group, and 62.30% in the non-PP group (adjusted OR 2.05; 95% CI 0.45–9.40; p = 0.353).Conclusions: TC could be a potential biomarker to predict the effects of TG-lowing therapy in patients with HLAP.


Paleobiology ◽  
1980 ◽  
Vol 6 (02) ◽  
pp. 146-160 ◽  
Author(s):  
William A. Oliver

The Mesozoic-Cenozoic coral Order Scleractinia has been suggested to have originated or evolved (1) by direct descent from the Paleozoic Order Rugosa or (2) by the development of a skeleton in members of one of the anemone groups that probably have existed throughout Phanerozoic time. In spite of much work on the subject, advocates of the direct descent hypothesis have failed to find convincing evidence of this relationship. Critical points are:(1) Rugosan septal insertion is serial; Scleractinian insertion is cyclic; no intermediate stages have been demonstrated. Apparent intermediates are Scleractinia having bilateral cyclic insertion or teratological Rugosa.(2) There is convincing evidence that the skeletons of many Rugosa were calcitic and none are known to be or to have been aragonitic. In contrast, the skeletons of all living Scleractinia are aragonitic and there is evidence that fossil Scleractinia were aragonitic also. The mineralogic difference is almost certainly due to intrinsic biologic factors.(3) No early Triassic corals of either group are known. This fact is not compelling (by itself) but is important in connection with points 1 and 2, because, given direct descent, both changes took place during this only stage in the history of the two groups in which there are no known corals.


Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.


Author(s):  
Leon Dmochowski

Electron microscopy has proved to be an invaluable discipline in studies on the relationship of viruses to the origin of leukemia, sarcoma, and other types of tumors in animals and man. The successful cell-free transmission of leukemia and sarcoma in mice, rats, hamsters, and cats, interpreted as due to a virus or viruses, was proved to be due to a virus on the basis of electron microscope studies. These studies demonstrated that all the types of neoplasia in animals of the species examined are produced by a virus of certain characteristic morphological properties similar, if not identical, in the mode of development in all types of neoplasia in animals, as shown in Fig. 1.


Author(s):  
J.R. Pfeiffer ◽  
J.C. Seagrave ◽  
C. Wofsy ◽  
J.M. Oliver

In RBL-2H3 rat leukemic mast cells, crosslinking IgE-receptor complexes with anti-IgE antibody leads to degranulation. Receptor crosslinking also stimulates the redistribution of receptors on the cell surface, a process that can be observed by labeling the anti-IgE with 15 nm protein A-gold particles as described in Stump et al. (1989), followed by back-scattered electron imaging (BEI) in the scanning electron microscope. We report that anti-IgE binding stimulates the redistribution of IgE-receptor complexes at 37“C from a dispersed topography (singlets and doublets; S/D) to distributions dominated sequentially by short chains, small clusters and large aggregates of crosslinked receptors. These patterns can be observed (Figure 1), quantified (Figure 2) and analyzed statistically. Cells incubated with 1 μg/ml anti-IgE, a concentration that stimulates maximum net secretion, redistribute receptors as far as chains and small clusters during a 15 min incubation period. At 3 and 10 μg/ml anti-IgE, net secretion is reduced and the majority of receptors redistribute rapidly into clusters and large aggregates.


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