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《古生物学报》1984,(1):106-106
The inaugural meeting of the National Bivalvia Re-search Group of PSC and the 1st Bivalvia symposiumwere held from Nov. 15 to 21. 1983 in Emei, Sichuan.75 participants, representing 53 organizations in cluding  相似文献   

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• Figures on professional registered nurses recently made available indicate that the ratio of active nurses to population in California in 1962 was 327 per 100,000 persons. The comparable figure nationally was 298/100,000. California ranked twentieth out of the 50 states and the District of Columbia.The percentage of all nurses actively engaged in nursing is considerably lower in California than in the total United States: 60.4 per cent compared with 65.3 per cent. This indicates that the shortage of nurses in California is more attributable to underutilization of potential manpower than to its absence.There are some identifiable categories of nurses in California in which the utilization of personnel is particularly low, as compared with other states. In terms of rates of utilization, the group of nurses over 60 years of age are most noticeably under-utilized, while in terms of numbers, married nurses could provide the greatest supply of extra nurses were their employment rate in the state equal to the national rate.The recruiting potential is a very great one, however, as this report indicates.  相似文献   

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Medium chain β-1-alkylglycosides show interesting mild detergent properties. Therefore, their synthesis and purification have been investigated and improved so as to permit preparation of 50–100 g amounts. Preparatory methods are presented for the already known compounds β-1-octyl-, β-1-nonyl and β-1-decyl-glucose and for the new compounds β-1-undecylglucose and β-1-dodecylmaltose. Some relevant properties such as melting point, optical rotation, critical micelle concentration and NMR-spectra have been determined. They illustrate the suitability of this class of detergents for membrane research.  相似文献   

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Abstract

ROESY and NOESY NMR spectroscopic analyses of the ribofuranosyl (1a), 2′-deoxyribofuranosyl (1b), and arabinofuranosyl (1c) derivatives of 6-formyluracil in (CD3)2SO and D2O solutions have established that each exclusive 7,05′-cyclic hemiacetal diastereomer of 1a,b and the major 7,O2′-cyclic hemiacetal diastereomer of 1c possess the 7R configuration. In addition, (7R)-1c has been shown to be thermodynamically more stable than (7S)-1c, contrary to our previous indication. A new, higher yielding synthetic route to 1a has been developed, 1b has been obtained for the first time in crystalline form, the route to 1c has been modified to better accommodate large scale preparations, and a new, fourth member of this class, 6-formylthymidine (1d), has been synthesized and its solution structures in (CD3)2SO, D2O, and CD3OD have been determined. Antitumor and antiviral evaluations of 1a-c have revealed no significant levels of activity.  相似文献   

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Background

The HPA-1 alloimmune system carried by the platelet integrin αIIbβ3 is the primary cause of alloimmune thrombocytopenia in Caucasians and the HPA-1b allele might be a risk factor for thrombosis. HPA-1a and -1b alleles are defined by a leucine and a proline, respectively, at position 33 in the β3 subunit. Although the structure of αIIbβ3 is available, little is known about structural effects of the L33P substitution and its consequences on immune response and integrin functions.

Methodology/Principal Findings

A complete 3D model of the L33-β3 extracellular domain was built and a P33 model was obtained by in silico mutagenesis. We then performed molecular dynamics simulations. Analyses focused on the PSI, I-EGF-1, and I-EGF-2 domains and confirmed higher exposure of residue 33 in the L33 β3 form. These analyses also showed major structural flexibility of all three domains in both forms, but increased flexibility in the P33 β3 form. The L33P substitution does not alter the local structure (residues 33 to 35) of the PSI domain, but modifies the structural equilibrium of the three domains.

Conclusions

These results provide a better understanding of HPA-1 epitopes complexity and alloimmunization prevalence of HPA-1a. P33 gain of structure flexibility in the β3 knee may explain the increased adhesion capacity of HPA-1b platelets and the associated thrombotic risk. Our study provides important new insights into the relationship between HPA-1 variants and β3 structure that suggest possible effects on the alloimmune response and platelet function.  相似文献   

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In 1919 the Animal Breeding Research Department was established in Edinburgh. This Department, later renamed the Institute of Animal Genetics, forged an international reputation, eventually becoming the centrepiece of a cluster of new genetics research units and institutions in Edinburgh after the Second World War. Yet despite its significance for institutionalising animal genetics research in the UK, the origins and development of the Department have not received as much scholarly attention as its importance warrants. This paper sheds new light on Edinburgh’s place in early British genetics by drawing upon recently catalogued archival sources including the papers of James Cossar Ewart, Regius Professor of Natural History at the University of Edinburgh between 1882 and 1927. Although presently a marginal figure in genetics historiography, Ewart established two sites for experimental animal breeding work between 1895 and 1911 and played a central role in the founding of Britain’s first genetics lectureship, also in 1911. These early efforts helped to secure government funding in 1913. However, a combination of the First World War, bureaucratic problems and Ewart’s personal ambitions delayed the creation of the Department and the appointment of its director by another six years. This paper charts the institutionalisation of animal breeding and genetics research in Edinburgh within the wider contexts of British genetics and agriculture in the early twentieth century.  相似文献   

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The existing literature on the development of recombinant DNA technology and genetic engineering tends to focus on Stanley Cohen and Herbert Boyer’s recombinant DNA cloning technology and its commercialization starting in the mid-1970s. Historians of science, however, have pointedly noted that experimental procedures for making recombinant DNA molecules were initially developed by Stanford biochemist Paul Berg and his colleagues, Peter Lobban and A. Dale Kaiser in the early 1970s. This paper, recognizing the uneasy disjuncture between scientific authorship and legal invention in the history of recombinant DNA technology, investigates the development of recombinant DNA technology in its full scientific context. I do so by focusing on Stanford biochemist Berg’s research on the genetic regulation of higher organisms. As I hope to demonstrate, Berg’s new venture reflected a mass migration of biomedical researchers as they shifted from studying prokaryotic organisms like bacteria to studying eukaryotic organisms like mammalian and human cells. It was out of this boundary crossing from prokaryotic to eukaryotic systems through virus model systems that recombinant DNA technology and other significant new research techniques and agendas emerged. Indeed, in their attempt to reconstitute ‹life’ as a research technology, Stanford biochemists’ recombinant DNA research recast genes as a sequence that could be rewritten thorough biochemical operations. The last part of this paper shifts focus from recombinant DNA technology’s academic origins to its transformation into a genetic engineering technology by examining the wide range of experimental hybridizations which occurred as techniques and knowledge circulated between Stanford biochemists and the Bay Area’s experimentalists. Situating their interchange in a dense research network based at Stanford’s biochemistry department, this paper helps to revise the canonized history of genetic engineering’s origins that emerged during the patenting of Cohen–Boyer’s recombinant DNA cloning procedures.  相似文献   

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Not a day passes where nanotechnology does not make headlines in the popular press, scientific journals, as well as in the regulatory arena. Environmental and public health activists are voicing a growing concern and focus on the risks potentially posed by nanotechnology and the ability of the government to regulate these new and exciting technologies. Whereas such concerns state the need for stringent, precautionary, and almost exclusionary approaches to the regulation of nanotechnology, many entities believe that a voluntary approach to these often novel materials and technologies is the appropriate and sensible path. In this editorial, we discuss the importance of nanotechnology, who cares, and the available options for approaching the regulation of this often novel technology. We focus on the U.S. Environmental Protection Agency (USEPA) and its voluntary regulatory data submission program as the preferred alternative. 2 2Comments are those of the authors and do not necessarily represent those of their employers. View all notes  相似文献   

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Mitochondrial dysfunction is considered to play an important role in the development of diabetic retinopathy. Recent evidence has also shown many similarities between diabetic retinopathy and a low grade chronic inflammatory disease. The aim of this study is to understand the interrelationship between proinflammtory mediator, IL-1β and mitochondrial dysfunction in the accelerated loss of capillary cells in the retina. Using IL-1β receptor gene knockout (IL-1R1?/?) diabetic mice, we have investigated the effect of regulation of IL-1β on mitochondrial dysfunction and mtDNA damage, and increased retinal capillary cell apoptosis and the development of retinopathy. Retinal mitochondrial dysfunction and mtDNA damage were significantly ameliorated in IL-1R1?/? mice, diabetic for ~10 months, compared to the wild-type diabetic mice. This was accompanied by protection of accelerated capillary cell apoptosis and the development of acellular capillaries, histopathology associated with diabetic retinopathy. Thus, mitochondrial damage could be one of the key events via which increased inflammation contributes to the activation of the apoptotic machinery resulting in the development of diabetic retinopathy, and the possible mechanism via which inflammation contributes to the development of diabetic retinopathy includes continuous fueling of the vicious cycle of mitochondrial damage, which could be disrupted by inhibitors of inflammatory mediators.  相似文献   

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Tony Hunter  James I. Garrels 《Cell》1977,12(3):767-781
The mRNAs for α-, β- and γ-actin have been characterized with respect to molecular weight and poly(A) content. Polyacrylamide gel electrophoresis under denaturing conditions shows that the mRNA for α-actin (muscle-specific actin) is approximately 4.6 × 105 daltons in size, and that the mRNAs for β- and γ-actin (nonmuscle actins) are much larger, approximately 6.6 × 105 daltons in size. We therefore calculate that the noncoding regions of the β- and γ-actin mRNAs contain about 800 nucleotides. This is in marked contrast to the noncoding regions of α-actin mRNA which contain only about 180 nucleotides. During electrophoresis in high-resolution nondenaturing gels, the β-actin mRNA migrates slightly slower than the γ-actin mRNA. This indicates either that β-actin mRNA is about 100 nucleotides longer than γ-actin mRNA, or that these mRNAs differ in secondary structure. Fractionation of actin mRNA on the basis of poly(A) content shows that a substantial portion of the β-actin mRNA, but very little of the α- or γ-actin mRNAs, fails to bind to oligo(dT)-cellulose. Much of this poly(A)-deficient β-actin mRNA, however, does bind to poly(U)-Sepharose, a substrate with higher affinity for short poly(A) sequences. This indicates that many of these β-actin mRNA molecules are polyadenylated, but that they have unusually short poly(A) tails. The finding that β- and γ-actins are translated from mRNAs of different electrophoretic mobility and different poly(A) content strongly suggests that these two closely related proteins are products of different genes.  相似文献   

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A particulate enzyme preparation from Phaseolus aureus (mung bean) seedlings catalyzed the synthesis of a water insoluble β-1,3-glucan from UDP-α-d-glucose (UDPG) at high concentrations (0.4~20 mm) and an alkaline insoluble β-1,3 and β-1,4-mixed glucan from UDPG at a low concentration (8.5 µm).

Furthermore, the two kinds of β-glucan synthetases which were investigated with two reaction systems at high and low concentrations of UDPG had different properties in optimal pH, stability of enzyme activity, and metallic ion requirement.  相似文献   

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Interactions between the extracellular matrix (ECM) and chondrocytes are of great importance for structure and function of cartilage. The present study was undertaken to answer the question whether caveolins take part in integrin-mediated cell–ECM interactions in the human cartilage. In samples of human knee joint cartilage, we detected the caveolin subtypes -1, -2, and -3 by immunohistochemical methods. Double-label experiments revealed a colocalization of caveolin with β1-integrin. Results of immunoprecipitation and immunoblotting assays show that β1-integrins associate with all three caveolin subtypes in human chondrocytes and indicate that they are part of the same complexes. Furthermore, immunoelectron microscopy shows the localization of β1-integrin in caveolae-like structures of the cell membrane. The data stimulate further investigations on the role of the caveolin–integrin complex for integrin-mediated signaling pathways in chondrocytes. Accepted: 17 December 1999  相似文献   

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Human α-, β-, and γ-synuclein (syn) are natively unfolded proteins present in the brain. Deposition of aggregated α-syn in Lewy bodies is associated with Parkinson's disease (PD) and γ-syn is known to be involved in both neurodegeneration and breast cancer. At physiological pH, while α-syn has the highest propensity for fibrillation followed by γ-syn, β-syn does not form any fibrils. Fibril formation in these proteins could be modulated by protein structure stabilizing osmolytes such as trehalose which has an exceptional stabilizing effect for globular proteins. We present a comprehensive study of the effect of trehalose on the conformation, aggregation, and fibril morphology of α-, β-, and γ-syn proteins. Rather than stabilizing the intrinsically disordered state of the synucleins, trehalose accelerates the rate of fibril formation by forming aggregation-competent partially folded intermediate structures. Fibril morphologies are also strongly dependent on the concentration of trehalose with ≤ 0.4M favoring the formation of mature fibrils in α-, and γ-syn with no effect on the fibrillation of β-syn. At ≥ 0.8M, trehalose promotes the formation of smaller aggregates that are more cytotoxic. Live cell imaging of preformed aggregates of a labeled A90C α-syn shows their rapid internalization into neural cells which could be useful in reducing the load of aggregated species of α-syn. The findings throw light on the differential effect of trehalose on the conformation and aggregation of disordered synuclein proteins with respect to globular proteins and could help in understanding the effect of osmolytes on intrinsically disordered proteins under cellular stress conditions.  相似文献   

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