Beta 2-microglobulin restriction of antigen presentation.

Antigens are generally thought to be recognized by cytotoxic T lymphocytes as peptides in the context of class I major histocompatibility proteins complex, which are heterodimers of heavy chains noncovalently associated with beta 2-microglobulin (beta 2m). The highly polymorphic nature of the heavy chains and their resulting ability to present different sets of peptides has presumably evolved to allow potent immune responses against most pathogens. By contrast, the polymorphism of beta 2m is limited; seven alleles are known in the mouse and only one has been identified in humans. beta 2-Microglobulin was consequently thought to have only structural functions: namely, to ensure correct folding of class I molecules and their transport to the cell surface. Although beta 2m is not implicated directly in the formation of the peptide binding site, we report here that it participates in the selection of MHC class I molecule-associated peptides.     

从中国大陆产银环蛇毒纯化的第三个K－神经毒素Ⅰ．毒素的纯化、鉴定与部分一级结构

从广东省花都市产银环蛇（Ｂｕｎｇａｒｕｓｍｕｌｔｉｃｉｎｔｕｓ）蛇毒纯化得到两个Ｋ－神经毒素（Ｋ－ＮＴ）：Ⅵ２ｄ峰及Ⅷ１ｂ峰。两者的分子量均为６５００，等电聚焦ＰＩ值均为９．１。Ⅵ２ｄ峰Ｎ端部分４３个氨基酸顺序与台湾姐环蛇的Ｋ－ＢＧＴ完全一致，后者是当前唯一可用于神经元烟碱乙酰胆碱受体分型的毒素探针。至此，从中国大陆产的银环蛇毒中找到Ｋ－ＮＴ家族中３个成员即：Ｋ－ＢＧＴ、Ｋ＿２－ＢＧＴ及Ｋ＿３－ＢＧＴ．     

Disrupted function and axonal distribution of mutant tyrosyl-tRNA synthetase in dominant intermediate Charcot-Marie-Tooth neuropathy

Charcot-Marie-Tooth (CMT) neuropathies are common disorders of the peripheral nervous system caused by demyelination or axonal degeneration, or a combination of both features. We previously assigned the locus for autosomal dominant intermediate CMT neuropathy type C (DI-CMTC) to chromosome 1p34-p35. Here we identify two heterozygous missense mutations (G41R and E196K) and one de novo deletion (153-156delVKQV) in tyrosyl-tRNA synthetase (YARS) in three unrelated families affected with DI-CMTC. Biochemical experiments and genetic complementation in yeast show partial loss of aminoacylation activity of the mutant proteins, and mutations in YARS, or in its yeast ortholog TYS1, reduce yeast growth. YARS localizes to axonal termini in differentiating primary motor neuron and neuroblastoma cultures. This specific distribution is significantly reduced in cells expressing mutant YARS proteins. YARS is the second aminoacyl-tRNA synthetase found to be involved in CMT, thereby linking protein-synthesizing complexes with neurodegeneration.     

Prostaglandin-like substances inPropionibacterium acnes. V. Activity profiles using cascade superfusion bioassay and platelet aggregation

Summary The activity spectrum of prostaglandin-like substances (PLS) fromP. acnes was investigated with cascade superfusion technique and by platelet aggregation assay. The biological activity of PLS resembles that of PGI₂: both relax bovine coronary artery, rabbit mesentric and coeliac arteries; both contract the rat stomach strip as well as both typically inhibit spontaneous movements of isolated guinea pig ileum. Also, similarly to PGI₂, PLS inhibits platelet aggregation regardless the inducer used. However, PLS possesses a specific antiaggregatory pattern on platelet, which indicates that these compounds are not indentical with primary prostaglandins or PGI₂.     

Effects of intracerebroventricular injections of angiotensin II on prolactin plasma levels in the Rhesus monkey

Summary Intracerebroventricular injections of angiotensin II (A II) induced a sharp and dose-dependent increase in plasma prolactin (PRL) levels in the awake Rhesus monkey. Our results suggest that in primates, A II may be involved in the mechanisms controlling PRL secretion.Acknowledgments. We thank Mrs. J. Arsaut and D. Verrier for excellent technical assistance. This work was supported by grants from INSERM (CRL No. 78.1.2656), DGRST (77.7.9654) and CNRS (ERA 493).     

Stem-cell therapy for cardiac disease

Heart failure is the leading cause of death worldwide, and current therapies only delay progression of the disease. Laboratory experiments and recent clinical trials suggest that cell-based therapies can improve cardiac function, and the implications of this for cardiac regeneration are causing great excitement. Bone-marrow-derived progenitor cells and other progenitor cells can differentiate into vascular cell types, restoring blood flow. More recently, resident cardiac stem cells have been shown to differentiate into multiple cell types present in the heart, including cardiac muscle cells, indicating that the heart is not terminally differentiated. These new findings have stimulated optimism that the progression of heart failure can be prevented or even reversed with cell-based therapy.     

P systems generating iso-picture languages

P systems generating rectangular arrays and hexagonal arrays have been studied in the literature, bringing together the two areas of theoretical computer science, namely membrane computing and picture languages. Recently, a new class of picture languages called the class of iso-picture languages generating interesting picture languages has been introduced. In this paper, we develop a class of tissue-like P systems with active membranes as a generative device for iso-picture languages.     

P systems generating iso-plcture languages

P systems generating rectangular arrays and hexagonal arrays have been studied in the literature,bringing together the two areas of theoretical computer science,namely membrane computing and picture languages.Recently,a new class of picture languages called the class of iso-picture languages generating interesting picture languages has been introduced.In this paper,we develop a class of tissue-like P systems with active membranes as a generative device for iso-picture languages.     

Trajectory P System

Membrane Computing is a branch of natural computing aiming to abstract computing ideas for the structure and the functioning of living cells as well as from the way the cells are organized in tissues or higher order structures. Trajectories are used as a tool for modeling language operations and other related objects. A trajectory P system consists of a membrane structure in which the object in each membrane is a collection of words and the evolutionary rules are given in terms of trajectories. In this paper, we present some properties of trajectory P systems.