Systemic ß adrenergic stimulation/ sympathetic nerve system stimulation influences intraocular RAS through cAMP in the RPE

Several lines of evidence support the existence of a renin-angiotensin system (RAS) in the retina that is separated from the blood stream by the retinal pigment epithelium (RPE). Under physiological conditions, increased activity of intraretinal RAS regulates neuronal activity of the retina but patho-physiologically participates in retinal degeneration such as hypertensive or diabetic retinopathy. Interestingly, the RPE appears to be a modulator of intraretinal RAS in response to changes in systemic RAS. As increased systemic RAS activity is associated with increased sympathetic tonus, we investigated whether systemic β-adrenergic stimulation of the RPE also modulates renin expression in the RPE. In vivo, the mouse RPE expresses the β-adrenergic receptor subtypes 1 and 2. Staining of retina sagittal sections showed tyrosine hydroxylase positive nerve endings in the choroid indicating adrenaline/noradrenaline production sites in close proximity to the RPE. Systemic infusion of isoproterenol increased renin expression in the RPE but not in the retina. This increase was sensitive to concomitant systemic application of the angiotensin-2 receptor-type-1 blocker losartan. In vitro analysis of renin gene expression using polarized porcine RPE showed that the activity of the renin promoter can be increased by cAMP stimulation (IBMX/forskolin) but was not influenced by angiotensin-2. Thus, with the identification of the β-adrenergic system we added a new regulator of the retinal RAS with relevance for retinal function and pathology. Furthermore, it appears that the RPE is not only a close interaction partner of the photoreceptors but also a regulator or retinal activity in general.

Renin cells with defective Gsα/cAMP signaling contribute to renal endothelial damage

Synthesis of renin in renal renin-producing cells (RPCs) is controlled via the intracellular messenger cAMP. Interference with cAMP-mediated signaling by inducible knockout of Gs-alpha (Gsα) in RPCs of adult mice resulted in a complex adverse kidney phenotype. Therein, glomerular endothelial damage was most striking. In this study, we investigated whether Gsα knockout leads to a loss of RPCs, which itself may contribute to the endothelial injury. We compared the kidney phenotype of three RPC-specific conditional mouse lines during continuous induction of recombination. Mice expressing red fluorescent reporter protein tdTomato (tdT) in RPCs served as controls. tdT was also expressed in RPCs of the other two strains used, namely with RPC-specific Gsα knockout (Gsα mice) or with RPC-specific diphtheria toxin A expression (DTA mice, in which the RPCs should be diminished). Using immunohistological analysis, we found that RPCs decreased by 82% in the kidneys of Gsα mice as compared with controls. However, the number of tdT-positive cells was similar in the two strains, demonstrating that after Gsα knockout, the RPCs persist as renin-negative descendants. In contrast, both renin-positive and tdT-labeled cells decreased by 80% in DTA mice suggesting effective RPC ablation. Only Gsα mice displayed dysregulated endothelial cell marker expression indicating glomerular endothelial damage. In addition, a robust induction of genes involved in tissue remodelling with microvascular damage was identified in tdT-labeled RPCs isolated from Gsα mice. We concluded that Gsα/renin double-negative RPC progeny essentially contributes for the development of glomerular endothelial damage in our Gsα-deficient mice.

Universal health coverage and intersectoral action for health: key messages from Disease Control Priorities, 3rd edition

The World Bank is publishing nine volumes of Disease Control Priorities, 3rd edition (DCP3) between 2015 and 2018. Volume 9, Improving Health and Reducing Poverty, summarises the main messages from all the volumes and contains cross-cutting analyses. This Review draws on all nine volumes to convey conclusions. The analysis in DCP3 is built around 21 essential packages that were developed in the nine volumes. Each essential package addresses the concerns of a major professional community (eg, child health or surgery) and contains a mix of intersectoral policies and health-sector interventions. 71 intersectoral prevention policies were identified in total, 29 of which are priorities for early introduction. Interventions within the health sector were grouped onto five platforms (population based, community level, health centre, first-level hospital, and referral hospital). DCP3 defines a model concept of essential universal health coverage (EUHC) with 218 interventions that provides a starting point for country-specific analysis of priorities. Assuming steady-state implementation by 2030, EUHC in lower-middle-income countries would reduce premature deaths by an estimated 4·2 million per year. Estimated total costs prove substantial: about 9·1% of (current) gross national income (GNI) in low-income countries and 5·2% of GNI in lower-middle-income countries. Financing provision of continuing intervention against chronic conditions accounts for about half of estimated incremental costs. For lower-middle-income countries, the mortality reduction from implementing the EUHC can only reach about half the mortality reduction in non-communicable diseases called for by the Sustainable Development Goals. Full achievement will require increased investment or sustained intersectoral action, and actions by finance ministries to tax smoking and polluting emissions and to reduce or eliminate (often large) subsidies on fossil fuels appear of central importance. DCP3 is intended to be a model starting point for analyses at the country level, but country-specific cost structures, epidemiological needs, and national priorities will generally lead to definitions of EUHC that differ from country to country and from the model in this Review. DCP3 is particularly relevant as achievement of EUHC relies increasingly on greater domestic finance, with global developmental assistance in health focusing more on global public goods. In addition to assessing effects on mortality, DCP3 looked at outcomes of EUHC not encompassed by the disability-adjusted life-year metric and related cost-effectiveness analyses. The other objectives included financial protection (potentially better provided upstream by keeping people out of the hospital rather than downstream by paying their hospital bills for them), stillbirths averted, palliative care, contraception, and child physical and intellectual growth. The first 1000 days after conception are highly important for child development, but the next 7000 days are likewise important and often neglected.

Interference with Gsα-Coupled Receptor Signaling in Renin-Producing Cells Leads to Renal Endothelial Damage

Intracellular cAMP, the production of which is catalyzed by the α-subunit of the stimulatory G protein (Gsα), controls renin synthesis and release by juxtaglomerular (JG) cells of the kidney, but may also have relevance for the physiologic integrity of the kidney. To investigate this possibility, we generated mice with inducible knockout of Gsα in JG cells and monitored them for 6 months after induction at 6 weeks of age. The knockout mapped exclusively to the JG cells of the Gsα-deficient animals. Progressive albuminuria occurred in Gsα-deficient mice. Compared with controls expressing wild-type Gsα alleles, the Gsα-deficient mice had enlarged glomeruli with mesangial expansion, injury, and FSGS at study end. Ultrastructurally, the glomerular filtration barrier of the Gsα-deficient animals featured endothelial gaps, thickened basement membrane, and fibrin-like intraluminal deposits, which are classic signs of thrombotic microangiopathy. Additionally, we found endothelial damage in peritubular capillaries and vasa recta. Because deficiency of vascular endothelial growth factor (VEGF) results in thrombotic microangiopathy, we addressed the possibility that Gsα knockout may result in impaired VEGF production. We detected VEGF expression in JG cells of control mice, and cAMP agonists regulated VEGF expression in cultured renin-producing cells. Our data demonstrate that Gsα deficiency in JG cells of adult mice results in kidney injury, and suggest that JG cells are critically involved in the maintenance and protection of the renal microvascular endothelium.

Persistent and inducible neogenesis repopulates progenitor renin lineage cells in the kidney

Renin lineage cells (RLCs) serve as a progenitor cell reservoir during nephrogenesis and after renal injury. The maintenance mechanisms of the RLC pool are still poorly understood. Since RLCs were also identified as a progenitor cell population in bone marrow we first considered that these may be their source in the kidney. However, transplantation experiments in adult mice demonstrated that bone marrow-derived cells do not give rise to RLCs in the kidney indicating their non-hematopoietic origin. Therefore we tested whether RLCs develop in the kidney through neogenesis (de novo differentiation) from cells that have never expressed renin before. We used a murine model to track neogenesis of RLCs by flow cytometry, histochemistry, and intravital kidney imaging. During nephrogenesis RLCs first appear at e14, form a distinct population at e16, and expand to reach a steady state level of 8-10% of all kidney cells in adulthood. De novo differentiated RLCs persist as a clearly detectable population through embryogenesis until at least eight months after birth. Pharmacologic stimulation of renin production with enalapril or glomerular injury induced the rate of RLC neogenesis in the adult mouse kidney by 14% or more than three-fold, respectively. Thus, the renal RLC niche is constantly filled by local de novo differentiation. This process could be stimulated consequently representing a new potential target to beneficially influence repair and regeneration after kidney injury.

The PPAR-gamma-binding sequence Pal3 is necessary for basal but dispensable for high-fat diet regulated human renin expression in the kidney

We reported earlier that PPAR-gamma regulates renin transcription through a human-specific atypical binding sequence termed hRen-Pal3. Here we developed a mouse model to investigate the functional relevance of the hRen-Pal3 sequence in vivo since it might be responsible for the increased renin production in obesity and thus for the development of accompanying arterial hypertension. We used bacterial artificial chromosome construct and co-placement strategy to generate two transgenic mouse lines expressing the human renin gene from identical genomic locus without affecting the intrinsic mouse renin expression. One line carried a wild-type hRen-Pal3 in the transgene (Pal3wt strain) and the other a mutated non-functional Pal3 (Pal3mut strain). Human renin expression was correctly targeted to the renin-producing juxtaglomerular (JG) cells of kidney in both lines. However, Pal3mut mice had lower basal human renin expression. Since human renin does not recognize mouse angiotensinogen as substrate, the blood pressure was not different between the strains. Stimulation of renin production with the angiotensin-converting enzyme inhibitor enalapril equipotentially stimulated the human renin expression in Pal3wt and Pal3mut mice. High-fat diet for 10 weeks which is known to activate PPAR-gamma failed to increase human renin mRNA in kidneys of either strain. These findings showed that the human renin PPAR-gamma-binding sequence hRen-Pal3 is essential for basal renin expression but dispensable for the cell-specific and high-fat diet regulated renin expression in the kidney.

Identification of Structural Features of Condensed Tannins That Affect Protein Aggregation

A diverse panel of condensed tannins was used to resolve the confounding effects of size and subunit composition seen previously in tannin-protein interactions. Turbidimetry revealed that size in terms of mean degree of polymerisation (mDP) or average molecular weight (amw) was the most important tannin parameter. The smallest tannin with the relatively largest effect on protein aggregation had an mDP of ~7. The average size was significantly correlated with aggregation of bovine serum albumin, BSA (mDP: r = -0.916; amw: r = -0.925; p<0.01; df = 27), and gelatin (mDP: r = -0.961; amw: r = -0.981; p<0.01; df = 12). The procyanidin/prodelphinidin and cis-/trans-flavan-3-ol ratios gave no significant correlations. Tryptophan fluorescence quenching indicated that procyanidins and cis-flavan-3-ol units contributed most to the tannin interactions on the BSA surface and in the hydrophobic binding pocket (r = 0.677; p<0.05; df = 9 and r = 0.887; p<0.01; df = 9, respectively). Circular dichroism revealed that higher proportions of prodelphinidins decreased the apparent α-helix content (r = -0.941; p<0.01; df = 5) and increased the apparent β-sheet content (r = 0.916; p<0.05; df = 5) of BSA.

Renin lineage cells repopulate the glomerular mesangium after injury

Mesangial cell injury has a major role in many CKDs. Because renin-positive precursor cells give rise to mesangial cells during nephrogenesis, this study tested the hypothesis that the same phenomenon contributes to glomerular regeneration after murine experimental mesangial injury. Mesangiolysis was induced by administration of an anti-mesangial cell serum in combination with LPS. In enhanced green fluorescent protein-reporter mice with constitutively labeled renin lineage cells, the size of the enhanced green fluorescent protein-positive area in the glomerular tufts increased after mesangial injury. Furthermore, we generated a novel Tet-on inducible triple-transgenic LacZ reporter line that allowed selective labeling of renin cells along renal afferent arterioles of adult mice. Although no intraglomerular LacZ expression was detected in healthy mice, about two-thirds of the glomerular tufts became LacZ positive during the regenerative phase after severe mesangial injury. Intraglomerular renin descendant LacZ-expressing cells colocalized with mesangial cell markers α8-integrin and PDGF receptor-β but not with endothelial, podocyte, or parietal epithelial cell markers. In contrast with LacZ-positive cells in the afferent arterioles, LacZ-positive cells in the glomerular tuft did not express renin. These data demonstrate that extraglomerular renin lineage cells represent a major source of repopulating cells for reconstitution of the intraglomerular mesangium after injury.

The nitric-oxide reductase from Paracoccus denitrificans uses a single specific proton pathway

The NO reductase from Paracoccus denitrificans reduces NO to N2O (2NO + 2H(+) + 2e(-) → N2O + H2O) with electrons donated by periplasmic cytochrome c (cytochrome c-dependent NO reductase; cNOR). cNORs are members of the heme-copper oxidase superfamily of integral membrane proteins, comprising the O2-reducing, proton-pumping respiratory enzymes. In contrast, although NO reduction is as exergonic as O2 reduction, there are no protons pumped in cNOR, and in addition, protons needed for NO reduction are derived from the periplasmic solution (no contribution to the electrochemical gradient is made). cNOR thus only needs to transport protons from the periplasm into the active site without the requirement to control the timing of opening and closing (gating) of proton pathways as is needed in a proton pump. Based on the crystal structure of a closely related cNOR and molecular dynamics simulations, several proton transfer pathways were suggested, and in principle, these could all be functional. In this work, we show that residues in one of the suggested pathways (denoted pathway 1) are sensitive to site-directed mutation, whereas residues in the other proposed pathways (pathways 2 and 3) could be exchanged without severe effects on turnover activity with either NO or O2. We further show that electron transfer during single-turnover reduction of O2 is limited by proton transfer and can thus be used to study alterations in proton transfer rates. The exchange of residues along pathway 1 showed specific slowing of this proton-coupled electron transfer as well as changes in its pH dependence. Our results indicate that only pathway 1 is used to transfer protons in cNOR.

Chicken ovalbumin upstream promoter transcription factor II regulates renin gene expression

This study aimed to investigate the possible involvement of the orphan nuclear receptor chicken ovalbumin upstream promoter transcription factor II (COUP-TFII) in the regulation of renin gene expression. COUP-TFII colocalized with renin in the juxtaglomerular cells of the kidney, which are the main source of renin in vivo. Protein-DNA binding studies demonstrated that COUP-TFII binds to an imperfect direct repeat COUP-TFII recognition sequence (termed hereafter proxDR) in the proximal renin promoter. Because cAMP signaling plays a central role in the control of the renin gene expression, we suggested that COUP-TFII may modulate this cAMP effect. Accordingly, knockdown of COUP-TFII in the clonal renin-producing cell lines As4.1 and Calu-6 diminished the stimulation of the renin mRNA expression by cAMP agonists. In addition, the mutation of the proxDR element in renin promoter reporter gene constructs abrogated the inducibility by cAMP. The proxDR sequence was found to be necessary for the function of a proximal renin promoter cAMP-response element (CRE). Knockdown of COUP-TFII or cAMP-binding protein (CREB), which is the archetypal transcription factor binding to CRE, decreased the basal renin gene expression. However, the deficiency of COUP-TFII did not further diminish the renin expression when CREB was knocked down. In agreement with the cell culture studies, mutant mice deficient in COUP-TFII have lower renin expression than their control strain. Altogether our data show that COUP-TFII is involved in the control of renin gene expression.

Pre-steady-state kinetic characterization of thiolate anion formation in human leukotriene C₄ synthase

Human leukotriene C₄ synthase (hLTC4S) is an integral membrane protein that catalyzes the committed step in the biosynthesis of cysteinyl-leukotrienes, i.e., formation of leukotriene C₄ (LTC₄). This molecule, together with its metabolites LTD₄ and LTE₄, induces inflammatory responses, particularly in asthma, and thus, the enzyme is an attractive drug target. During the catalytic cycle, glutathione (GSH) is activated by hLTC4S that forms a nucleophilic thiolate anion that will attack LTA₄, presumably according to an S(N)2 reaction to form LTC₄. We observed that GSH thiolate anion formation is rapid and occurs at all three monomers of the homotrimer and is concomitant with stoichiometric release of protons to the medium. The pK(a) (5.9) for enzyme-bound GSH thiol and the rate of thiolate formation were determined (k(obs) = 200 s⁻¹). Taking advantage of a strong competitive inhibitor, glutathionesulfonic acid, shown here by crystallography to bind in the same location as GSH, we determined the overall dissociation constant (K(d((GS) = 14.3 μM). The release of the thiolate was assessed using a GSH release experiment (1.3 s⁻¹). Taken together, these data establish that thiolate anion formation in hLTC4S is not the rate-limiting step for the overall reaction of LTC₄ production (k(cat) = 26 s⁻¹), and compared to the related microsomal glutathione transferase 1, which displays very slow GSH thiolate anion formation and one-third of the sites reactivity, hLTC4S has evolved a different catalytic mechanism.

Substrate control of internal electron transfer in bacterial nitric-oxide reductase

Nitric -oxide reductase (NOR) from Paracoccus denitrificans catalyzes the reduction of nitric oxide (NO) to nitrous oxide (N(2)O) (2NO + 2H(+) + 2e(-) -->N(2)O + H(2)O) by a poorly understood mechanism. NOR contains two low spin hemes c and b, one high spin heme b(3), and a non-heme iron Fe(B). Here, we have studied the reaction between fully reduced NOR and NO using the "flow-flash" technique. Fully (four-electron) reduced NOR is capable of two turnovers with NO. Initial binding of NO to reduced heme b(3) occurs with a time constant of approximately 1 micros at 1.5 mM NO, in agreement with earlier studies. This reaction is [NO]-dependent, ruling out an obligatory binding of NO to Fe(B) before ligation to heme b(3). Oxidation of hemes b and c occurs in a biphasic reaction with rate constants of 50 s(-1) and 3 s(-1) at 1.5 mM NO and pH 7.5. Interestingly, this oxidation is accelerated as [NO] is lowered; the rate constants are 120 s(-1) and 12 s(-1) at 75 microM NO. Protons are taken up from solution concomitantly with oxidation of the low spin hemes, leading to an acceleration at low pH. This effect is, however, counteracted by a larger degree of substrate inhibition at low pH. Our data thus show that substrate inhibition in NOR, previously observed during multiple turnovers, already occurs during a single oxidative cycle. Thus, NO must bind to its inhibitory site before electrons redistribute to the active site. The further implications of our data for the mechanism of NO reduction by NOR are discussed.

Exploring the terminal region of the proton pathway in the bacterial nitric oxide reductase

The c-type nitric oxide reductase (cNOR) from Paracoccus (P.) denitrificans is an integral membrane protein that catalyzes NO reduction; 2NO+2e(-)+2H(+)-->N(2)O+H(2)O. It is also capable of catalyzing the reduction of oxygen to water, albeit more slowly than NO reduction. cNORs are divergent members of the heme-copper oxidase superfamily (HCuOs) which reduce NO, do not pump protons, and the reaction they catalyse is non-electrogenic. All known cNORs have been shown to have five conserved glutamates (E) in the catalytic subunit, by P. denitrificans numbering, the E122, E125, E198, E202 and E267. The E122 and E125 are presumed to face the periplasm and the E198, E202 and E267 are located in the interior of the membrane, close to the catalytic site. We recently showed that the E122 and E125 define the entry point of the proton pathway leading from the periplasm into the active site [U. Flock, F.H. Thorndycroft, A.D. Matorin, D.J. Richardson, N.J. Watmough, P. Adelroth, J. Biol. Chem. 283 (2008) 3839-3845]. Here we present results from the reaction between fully reduced NOR and oxygen on the alanine variants of the E198, E202 and E267. The initial binding of O(2) to the active site was unaffected by these mutations. In contrast, proton uptake to the bound O(2) was significantly inhibited in both the E198A and E267A variants, whilst the E202A NOR behaved essentially as wildtype. We propose that the E198 and E267 are involved in terminating the proton pathway in the region close to the active site in NOR.

Lymphocyte traffic through lymph nodes during cell shutdown

Antigenic challenge of lymph nodes in sheep has marked effects on lymphocyte traffic through lymph nodes. The non-specific effects include a marked reduction in lymphocyte output in efferent lymph without a corresponding decrease in lymph flow--a phenomenon known as cell shutdown. With certain antigens there is a total disappearance of B lymphocytes during cell shutdown. The phenomenon can be reproduced in unprimed lymph nodes whenever localized complement activation occurs within the node. This also induces the release of prostaglandins, particularly PGE2. These results suggest that cell shutdown might be a two-step process involving both complement and prostaglandins. Repeated stimulation of nodes with antigen also has considerable effects on the traffic of antigen-specific lymphocytes. Antigen localized within the node can promote the selective entry into the node of T lymphocytes specific for the challenge antigen. Consequently there is a net loss from the whole animal of T cells reactive to the challenge antigen. These results are discussed in relation to lymphocyte recirculation through antigen-stimulated lymph nodes.

Complement before molecular biology

Complement activity was first described in the 1890s and the characterisation of this highly complex system has continued ever since. This review traces the history of complement research from its beginnings until it was transformed by the advent of molecular biology in the 1980s. It takes as a focus point the CIBA symposium on Complement held in London in May 1964 and reflects-and is slanted by-the views and research experience of the author.

Consensus statements from the Second International Lung Cancer Molecular Biomarkers Workshop: a European strategy for developing lung cancer molecular diagnostics in high risk populations

The Second Molecular Biomarkers Workshop was held at the Roy Castle International Centre for Lung Cancer Research in Liverpool, in June 2001 and it brought together experts in the clinical, epidemiological and molecular-pathology of lung cancer from Europe and the USA, to address issues surrounding the development of a European strategy for early lung cancer detection. The 2001 Workshop Breakout Groups concentrated on the current challenges in the early detection of lung cancer which need to be addressed in the light of the recent surge in interest in many countries for mounting new clinical trials to evaluate the utility of Spiral CT in early lung cancer detection. If population-based trials of CT screening are mounted it will also be a favorable clinical environment in which to evaluate efficiently recent advances in molecular screening and genotyping. The Workshop focused specifically on: a) clinical and molecular biomarkers, b) sputum as an early detection and diagnostic tool, c) validation of molecular markers prior to their use in early detection trials and d) ethical issues that have to be considered in early lung cancer detection trials. A distillation of the Workshop discussions is given in this article.

Complement-induced release of monocyte chemotactic protein-1 from human smooth muscle cells. A possible initiating event in atherosclerotic lesion formation

Increasing evidence suggests that complement activation might represent an important mechanism in early atherogenesis. Thus, complement components, in particular the membrane attack complex (MAC) C5b-9(m), have been isolated from human atherosclerotic lesions. Furthermore, complement activation is known to occur in atherosclerotic lesions induced in experimental animals, and the severity of cholesterol-induced plaques is markedly reduced in complement-deficient animals. During atherogenesis monocytes are recruited into the arterial wall, and a potent chemoattractant for monocytes, monocyte chemotactic protein-1 (MCP-1), is expressed by vascular smooth muscle cells (SMCs). We hypothesized that generation of MACs on SMCs during the activation of complement might lead to the release of MCP-1 and hence to monocyte recruitment. In this study, MACs were generated on human SMCs in vitro by sequential addition of the purified complement components C5b6, C7, C8, and C9. This supernatant of the culture was chemotactic for freshly isolated peripheral blood monocytes in a modified Boyden chamber. The chemotactic activity of the supernatant was abolished by anti-MCP-1 blocking antibodies but not by an isotype-matched antibody against an irrelevant antigen. The release of chemotactic activity was dependent on the dose of MAC formed on SMCs and was demonstrated within 10 minutes of exposure of the cells. The data support the hypothesis that complement-mediated release of MCP-1 from SMCs might be important in the recruitment of monocytes into the developing atherosclerotic lesion and could be an important initiating event in atherogenesis.

Structure of complement poly-C9 determined in projection by cryo-electron microscopy and single particle analysis

The ring-like complement 'lesions' found on membranes of complement lysed cells comprise a complex of components C5b through C9 that coalesce to form hollow cylinders which penetrate the membrane bilayer and create lytic pores. Walls of these C5b-9 membrane attack complex cylinders may consist primarily of the C9 component, since samples of purified, isolated C9 can polymerize into cylindrical structures which appear identical with the fully assembled C5b-9 complex. The structure of these poly-C9 molecules has been investigated using the techniques of cryo-electron microscopy and single particle analysis. Sets of single poly-C9 particles viewed as rings were selected from cryo-EM images, then particles were aligned and treated by correspondence analysis to identify the principle interparticle similarities and variations. The highest ranking variation found was the presence or absence of a dense inner ring of protein density. Other important variations were interpreted as different types of particle tilt. These results were used in selecting a subgroup of untilted particles for averaging and symmetry analysis. The rotational power spectrum of the initial average suggested 13-fold symmetry. The 13-fold symmetry was used to select and group particles for further analysis. Individual particles were 13-fold rotational averaged and those with enhanced peripheral features were placed into either a right-handed subgroup or into a left-handed subgroup based on orientation of the peripheral features. Particles within each group were aligned and averaged, and a poly-C9 structure was produced which shows important structural details and from which the C9 monomer structure can be deduced. The poly-C9 structure contains a dense inner ring of diameter between 113-181 A and which is modulated into 13 discrete peaks with peak-to-peak separation of approx. 35 A. The dense inner ring is surrounded by a less dense, concentric outer rim extending to 254 A diameter. The outer rim contains projections that are contiguous with the inner peaks but are skewed relative to the ring radius to produce the appearance of a pin-wheel. These projections correspond with the peripheral features picked up in the rotationally averaged individual particles; the left- or right-handed orientation of projections may result from the up/down orientation of individual particles in ice. The C9 monomer structure within the cylinder is suggested by the density distribution. The monomer would be a rod with diameter of 35 A, oriented parallel to the cylinder axis and would be roughly perpendicular to a membrane.(ABSTRACT TRUNCATED AT 400 WORDS)

Cell adhesion and migration of different human colon cell lines and primary tumors

Several cell lines derived from colon tumors (HT-29, WiDr, PT4, PT5) and from human liver metastases (LM3) and primary human colon tumor cells (PTR) were compared with regard to their ability to migrate and to attach to different substrates (collagen G, laminin, fibronectin). Cells from the WiDr cell lines migrated actively, whereas the other cell lines, and LM3 and the PTs showed almost no migratory activity. The attachment efficiency was best in all cell lines assayed when tested on collagen followed by laminin and fibronectin as substrates. The HT-29 cells showed the strongest adhesion to all substrates, while the adhesiveness of PT4, PT5, and LM3 was reduced. The WiDr cells which migrated best showed the lowest adhesion to the substrates.

Transport of proteins into chloroplasts. Binding of nuclear-coded chloroplast proteins to the chloroplast envelope

A system has been constructed in vitro for the binding of cytoplasmically synthesized chloroplast proteins to the chloroplast envelope which precedes the uptake into the organelle in vivo. Isolated chloroplast envelopes from young pea or spinach are capable of binding the majority of proteins obtained by translation of poly(A)-containing RNA from greening plants in vitro. Among the bound proteins the precursors to the light-harvesting chlorophyll a/b apoprotein and the small subunit of ribulose-1,5-bisphosphate carboxylase are prominent. Binding is an intrinsic property of the envelope membrane and does not require energy in the form of ATP. Bound proteins remain on the surface of the envelope vesicles and can be digested by protease. Binding is complete within minutes, shows a high affinity of the reactants, and is non-ionic in nature. Protein binding is specific for translation products of poly(A)-containing RNA from greening plants. Precursors to chloroplast protein are bound preferentially as compared to the mature proteins. The specificity is further demonstrated by the low binding of proteins obtained by run-off translation of polysomes. Binding of radioactive labeled proteins is subject to competition by excess unlabeled homologous proteins. Once bound, the proteins are withdrawn from competition indicating a high binding stability. All the properties found for binding of proteins to isolated envelopes are consistent with the concept of the so-called envelope carrier hypothesis.

[Aortic and mitral monovalvular replacements. Comparison of the ball prosthesis of Starr-Edwards (1260-6120) and the tilting disc prosthesis of Bjork-Shiley. Series of 390 patients]

The evaluation of short and long term replacement by the Björk-Shiley tilting disc prosthesis (BS) and by the Starr-Edwards ball and cage prosthesis (SE) was carried out on a series of 390 consecutive patients. In mitral replacement, operative mortality rate (SE 5.9 P. 100 - BS 4.8 P. 100), 5 year actuarial survival (SE 79.8 P. 100 +/- 3.8 P. 100 - BS 86.3 P. 100 +/- 9 p. 100) incidence of thromboembolic complications and valvular thrombosis (SE 1.6 P. 100 - BS 1.3 P. 100) as well as the degree of post-operative improvement were virtually identical in both types of prosthesis. Likewise, in aortic valve replacement, operative mortality rate (SE 4 p. 100 - BS 3.2 p. 100), 5 year survival (SE 82 +/- 7.8 P. 100 - BS 86 +/- 3.3 p. 100) incidence of thromboembolic complications (SE 2.2 p. 100 - BS 1.8 p. 100) and the degree of post-operative improvement were not statistically different. However, the incidence of sudden death was statistically smaller with a BS prosthesis than with a SE prosthesis (respectively 1.6 p. 100 and 6.9 p. 100).

Genetics of the complement system

The complement system, unlike the coagulation system, was largely characterized by in-vitro techniques which did not make use of genetically deficient plasmas. The existence of the genetically deficient plasmas. The existence of the genetically deficient subjects therefore has served largely to increase our knowledge of the in-vivo role of complement. At the present time its clearest role is in the resistance to infection; obviously in the case of C3 deficiency and bacterial infection and possibly more subtly in the case of deficiency of the early active complement components and low virulence organisms. There is so far no evidence that genetic complement deficiency interferes with antibody formation or with the generation of tolerance as has been suggested in the pas (Azar et al, 1968; Dukor and Hartmann, 1973).