Glucose-6-phosphate dehydrogenase variants in Hawaii.

Sequence analysis has been performed on the DNA of 13 glucose-6-phosphate dehydrogenase (G6PD) deficient males from Hawaii, 6 of Filipino, 6 of Laotian, and 1 of Chinese extraction. Four different mutations were found: A-->T at cDNA nt 835, G-->A at nt 871, C-->T at nt 1360, and G-->A at nt 1388. The mutations at nt 835 and nt 1360 have not been described previously, and the latter, in particular, appears to be relatively common. The nt 1360 mutation changes the same codon as is altered in a previously described mutation, G6PD Andalus.     

Deconvoluting lung evolution: from phenotypes to gene regulatory networks

Speakers in this symposium presented examples of respiratoryregulation that broadly illustrate principles of evolution fromwhole organ to genes. The swim bladder and lungs of aquaticand terrestrial organisms arose independently from a commonprimordial "respiratory pharynx" but not from each other. Pathwaysof lung evolution are similar between crocodiles and birds buta low compliance of mammalian lung may have driven the developmentof the diaphragm to permit lung inflation during inspiration.To meet the high oxygen demands of flight, bird lungs have evolvedseparate gas exchange and pump components to achieve unidirectionalventilation and minimize dead space. The process of "screening"(removal of oxygen from inspired air prior to entering the terminalunits) reduces effective alveolar oxygen tension and potentiallyexplains why nonathletic large mammals possess greater pulmonarydiffusing capacities than required by their oxygen consumption.The "primitive" central admixture of oxygenated and deoxygenatedblood in the incompletely divided reptilian heart is actuallyco-regulated with other autonomic cardiopulmonary responsesto provide flexible control of arterial oxygen tension independentof ventilation as well as a unique mechanism for adjusting metabolicrate. Some of the most ancient oxygen-sensing molecules, i.e.,hypoxia-inducible factor-1alpha and erythropoietin, are up-regulatedduring mammalian lung development and growth under apparentlynormoxic conditions, suggesting functional evolution. Normalalveolarization requires pleiotropic growth factors acting viahighly conserved cell–cell signal transduction, e.g.,parathyroid hormone-related protein transducing at least partlythrough the Wingless/int pathway. The latter regulates morphogenesisfrom nematode to mammal. If there is commonality among thesediverse respiratory processes, it is that all levels of organization,from molecular signaling to structure to function, co-evolveprogressively, and optimize an existing gas-exchange framework.     

SINC,a type III secreted protein of Chlamydia psittaci,targets the inner nuclear membrane of infected cells and uninfected neighbors

SINC, a new type III secreted protein of the avian and human pathogen Chlamydia psittaci, uniquely targets the nuclear envelope of C. psittaci–infected cells and uninfected neighboring cells. Digitonin-permeabilization studies of SINC-GFP–transfected HeLa cells indicate that SINC targets the inner nuclear membrane. SINC localization at the nuclear envelope was blocked by importazole, confirming SINC import into the nucleus. Candidate partners were identified by proximity to biotin ligase-fused SINC in HEK293 cells and mass spectrometry (BioID). This strategy identified 22 candidates with high confidence, including the nucleoporin ELYS, lamin B1, and four proteins (emerin, MAN1, LAP1, and LBR) of the inner nuclear membrane, suggesting that SINC interacts with host proteins that control nuclear structure, signaling, chromatin organization, and gene silencing. GFP-SINC association with the native LEM-domain protein emerin, a conserved component of nuclear “lamina” structure, or with a complex containing emerin was confirmed by GFP pull down. Our findings identify SINC as a novel bacterial protein that targets the nuclear envelope with the capability of globally altering nuclear envelope functions in the infected host cell and neighboring uninfected cells. These properties may contribute to the aggressive virulence of C. psittaci.     

Inhibition of sickle red cell adhesion and vasoocclusion in the microcirculation by antioxidants

In sickle cell anemia (SCA), inflammatory (i.e., intravascular sickling and transient vasoocclusive) events result in chronic endothelial activation. In addition to sickling behavior, sickle (SS) red blood cells exhibit abnormal interaction with the vascular endothelium, which is considered to have an important role in initiation of vasoocclusion. Upregulation of endothelial adhesion molecules caused by oxidants (and cytokines) may lead to increased SS red cell adhesion. We hypothesize that endothelial activation is indispensable in SS red cell adhesion to the endothelium and that antioxidants will have an inhibitory effect on this interaction. We examined the effect of selected antioxidants in ex vivo mesocecum vasculature, a well-established model that allows measurement of hemodynamic parameters and, by intravital microscopy, can allow quantification of adhesion. We tested antioxidant enzymes (SOD and catalase) and an intravascular SOD mimetic, polynitroxyl albumin (PNA), in the presence of platelet-activating factor (PAF); the latter causes endothelial oxidant generation and endothelial activation, which characterize SCA. In ex vivo preparations, PAF not only induced marked endothelial oxidant generation, it also enhanced SS red cell adhesion, resulting in frequent blockage of small-diameter venules. The adhesion, inversely related to venular diameter, and vasoocclusion were markedly inhibited by antioxidants, resulting in improved hemodynamics. PNA, the most effective antioxidant, also abolished SS red cell adhesion in non-PAF-activated preparations. Thus SS red cell adhesion and related vasoocclusion may be ameliorated by antioxidant therapy with a stable and long-acting molecule (e.g., PNA).