抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

An endothelium-derived 21-residue vasoconstrictor peptide, endothelin, has been isolated, and shown to be one of the most potent vasoconstrictors known. Cloning and sequencing of preproendothelin complementary DNA shows that mature endothelin is generated through an unusual proteolytic processing, and regional homologies to a group of neurotoxins suggest that endothelin is an endogenous modulator of voltage-dependent ion channels. Expression of the endothelin gene is regulated by several vasoactive agents, indicating the existence of a novel cardiovascular control system.

/pdf/a-novel-potent-vasoconstrictor-peptide-produced-by-vascular-4zvh0kyupn.pdf

A novel potent vasoconstrictor peptide produced by vascular endothelial cells.

Vascular endothelial growth factor (VEGF) was purified from media conditioned by bovine pituitary folliculostellate cells (FC). VEGF is a heparin-binding growth factor specific for vascular endothelial cells that is able to induce angiogenesis in vivo. Complementary DNA clones for bovine and human VEGF were isolated from cDNA libraries prepared from FC and HL60 leukemia cells, respectively. These cDNAs encode hydrophilic proteins with sequences related to those of the A and B chains of platelet-derived growth factor. DNA sequencing suggests the existence of several molecular species of VEGF. VEGFs are secreted proteins, in contrast to other endothelial cell mitogens such as acidic or basic fibroblast growth factors and platelet-derived endothelial cell growth factor. Human 293 cells transfected with an expression vector containing a bovine or human VEGF cDNA insert secrete an endothelial cell mitogen that behaves like native VEGF.

https://science.sciencemag.org/content/sci/246/4935/1306.full.pdf

Vascular endothelial growth factor is a secreted angiogenic mitogen

: Successful Software reuse requires the systematic discovery and exploitation of commonality across related software systems. By examining related software systems and the underlying theory of the class of systems they represent, domain analysis can provide a generic description of the requirements of that class of systems and a set of approaches for their implementation. This report will establish methods for performing a domain analysis and describe the products of the domain analysis process. To illustrate the application of domain analysis to a representative class of software systems, this report will provide a domain analysis of window management system software.

/pdf/feature-oriented-domain-analysis-foda-feasibility-study-2zsj0a30fo.pdf

Feature-Oriented Domain Analysis (FODA) Feasibility Study

Because the critical central regions of Active Galactic Nuclei (AGN) and quasars are strongly nonspherical but spatially unresolved, orientation effects have been the source of much confusion. In fact, it now appears that much of the variety in AGN types is just the result of varying orientation relative to the line of sight. We can define an extreme hypothesis,, the straw person model (SPM), in which there are two basic types of AGN: the radio quiets and the radio louds. For each type there is a range in intrinsic luminosity, and the luminosity controls some properties such as the Fanaroff and Riley classes. However, at a given intrinsic luminosity, all other properties such as spectroscopic classification and VLBI component speeds are ascribed to orientation. This model is only a caricature of the unification idea, and is already ruled out on many grounds, but it will be useful for organizing the discussion. I’ll describe what I consider to be convincing evidence that orientation effects are important and widespread. The true situation may be in some sense half way between the SPM and the hypothesis that orientation doesn’t affect classification at aIl. To us optimists, the orienration cup is half full rather than half empty. Although it is too soon to say for sure, the hypothesis that most objects’ classifications would be different if seen from other directions is a tenable one today.

http://www.physics.purdue.edu/%7Emlister/articles/antonucci1993_ann_rev.pdf

Unified models for active galactic nuclei and quasars

Background : Urinary metabolite measurements are often normalized to levels of the ubiquitous metabolite creati- nine (CRT) to take account of variations in fl export. Following CRT normalization, excesses of porphyrins and isoprostanes have been reported in the urines of children with neurodevelopmental disorders. It was suggested ( Whiteley et al. , 2006 , Pediatr. Int. 2006; 48 : 292 - 297) that urinary CRT levels may be depressed in children with autism spectrum disorders. This prompted re-evaluation of CRT levels in such children. Methods : First matinal urinary CRT levels were compared between subjects in different diagnostic categories includ- ing autistic disorder, pervasive developmental disorder not otherwise specifi ed (PDD-NOS) and hyperactivity, before and after correction for age and gender. A larger reference group, consisting of subjects with unrelated disorders and Asperger disorder, with no reported porphyrin excess, was also compared to the group with autistic disorder, both for CRT and for porphyrin (coproporphyrin, COPRO) excess. Results : No signifi cant difference in CRT was observed between any of the categories analyzed, also when corrected for age and gender. In contrast, urinary COPRO levels were signifi cantly higher in autistic disorder versus reference groups, either when expressed as absolute values (independent of CRT levels) or when normalized to CRT. Conclusions : These data do not support a systematic reduction in urinary CRT levels in subjects with autism spectrum disorders including autistic disorder and PDD-NOS. Urinary COPRO excess in autistic disorder was not associated with or consequent upon urinary CRT defi ciency. Differences between affected and control subjects in age and sampling time, as reported by Whiteley et al. , may underlie the apparent CRT reduction.

Porphyrinuria in childhood autistic disorder is not associated with urinary creatinine deficiency

The firA (Ts)200 mutation not only eliminates the resistance to rifampin of certain genetically resistant strains, but, moreover, renders ribonucleic acid synthesis thermolabile. The firA gene has been mapped by P1 tranduction and is located extremely close to the structural gene for deoxyribonucleic acid polymerase III at 4 min on the Escherichia coli linkage map.

Fine-structure mapping of the firA gene, a locus involved in the phenotypic expression of rifampin resistance in Escherichia.

Lactase-phlorizin hydrolase (LPH), a major digestive enzyme in the small intestine of newborns, is synthesized as a high-molecular-mass precursor comprising four tandemly repeated domains. Proteolytic cleavage of the precursor liberates the pro segment (LPHalpha) corresponding to domains I and II and devoid of known enzymic function. The mature enzyme (LPHbeta) comprises domains III and IV and is anchored in the brush border membrane via a C-terminal hydrophobic segment. To analyse the roles of the different domains of LPHalpha and LPHbeta, and the interactions between them, we have engineered a series of modified derivatives of the rat LPH precursor. These were expressed in cultured cells under the control of a cytomegalovirus promoter. The results show that recombinant LPHbeta harbouring both domains III and IV produces lactase activity. Neither domain III nor IV is alone sufficient to generate active enzyme, although the corresponding proteins are transport-competent. Tandem duplication of domains III or IV did not restore lactase activity, demonstrating the separate roles of both domains within LPHbeta. Further, the development of lactase activity did not require LPHalpha; however, LPHalpha potentiated the production of active LPHbeta but the individual LPHalpha subdomains I and II were unable to do so. Lactase activity and targeting required the C-terminal transmembrane anchor of LPH; this requirement was terminal transmembrane anchor or LPH; this requirement was not satisfied by the signal/anchor region of another digestive enzyme: sucrase-isomaltase. On the basis of this study we suggest that multiple levels of intramolecular interactions occur within the LPH precursor to produce the mature enzyme, and that the repeat domains of the precursor have distinct and specific functions in protein processing, substrate recognition and catalysis. We propose a functional model of LPHbeta in which substrate is channelled from an entry point located within domain II to the active site located in domain IV.

/pdf/functional-diversity-and-interactions-between-the-repeat-3jrh7x9arn.pdf

Functional diversity and interactions between the repeat domains of rat intestinal lactase

Purpose: The systemic concentration of dehydroepiandrosterone decreases with age in primates while in humans intraocular pressure (IOP) increases with aging. This study was designed

Influence of Dehydroepiandrosterone on Rabbit Intraocular Pressure

This review endeavours to provide both a concise and a useful summary of the process of transcription in Escherichia coli. Whilst I attempt to present a comprehensive survey of the literature, I have tried to include a relatively large number of recent publications from which the reader can readily obtain a more detailed listing. In the absence of specific mention in the text the reader is advised to consult Ref. 1.

Richard Lathe

Papers

Porphyrinuria in childhood autistic disorder is not associated with urinary creatinine deficiency

Fine-structure mapping of the firA gene, a locus involved in the phenotypic expression of rifampin resistance in Escherichia.

Functional diversity and interactions between the repeat domains of rat intestinal lactase

Influence of Dehydroepiandrosterone on Rabbit Intraocular Pressure

RNA polymerase of Escherichia coli.