Streak Formation Research Articles

Cholesterol crystal-induced endothelial cell activation is complement-dependent and mediated by TNF

Cholesterol crystals are known to be a hallmark of atherosclerosis with recent studies demonstrating deposition of these crystals in early fatty streak formation as well as penetrating the intima following plaque rupture. Inflammation has also become a central focus in atheroma development and endothelial cell activation is recognized as necessary for the recruitment of inflammatory cells to the plaque. However, the extent to which cholesterol crystals can induce inflammation and activate endothelial cells is not known. To investigate this, we developed a novel model activating human umbilical vein endothelial cells using lepirudin anticoagulated human whole blood. We found that cholesterol crystals caused a marked and dose-dependent increase in the adhesion molecules E-selectin and ICAM-1 on the surface of the endothelial cells after incubation with whole blood. There was no activation of the cells when the crystals were incubated in medium alone, or in human serum, despite substantial crystal-induced complement activation in serum. Complement inhibitors at the C3 and C5 levels reduced the whole blood induced endothelial cell activation by up to 89% (p<0.05) and abolished TNF release (p<0.01). Finally, the TNF inhibitor infliximab reduced endothelial activation to background levels (p<0.05). In conclusion, these data demonstrate that endothelial activation by cholesterol crystals is mediated by complement-dependent TNF release, and suggests that complement-inhibition might have a role in alleviating atherosclerosis-induced inflammation.

Silver Streaks on Surface of Injected Thermoplastic Parts

Abstract Silver streaks on injected thermoplastic parts are the undesirable features, considered as a visual surface defect. If they appear, elimination of this technological problem can be very difficult, especially in case the cause of their occurrence is not actually known. In this study, the detailed analysis of silver streaks formation was carried out. At first, the defect was microscopically studied. Then, the several analyses were performed to find the cause of silver streaks formation. Finally, solutions to the problem and elimination and this kind of surface defect were suggested.

New Observations regarding Staging Turkey Embryos from Oviposition through Primitive Streak Formation

The normal developmental sequence of the turkey embryo from the initial cleavage divisions through hypoblast formation has been described previously in 11 separate stages based on the progressive morphological differentiation of the embryo (Gupta and Bakst, Turkey embryo staging from cleavage through hypoblast formation. J. Morphol., 217, 313–325, 1993). However, in recent preliminary studies, our attempts to apply this stage table to describe the stages of embryo development were not successful. Therefore, we re-evaluated the development sequence of the turkey using eggs obtained from modern day commercial lines. Embryos from unincubated eggs and eggs incubated at different time intervals up to 25 hour were examined. In contrast to the observations by Gupta and Bakst, embryos from unincubated eggs lack an area pellucida (AP) but are characterised by dense clusters of cells that do not begin to dissipate and begin forming the AP until after 3–4 hours of incubation. Koller's sickle may or may not be present prior to and during hypoblast formation. Based on these new observations, a revised stage table including the above observations is presented to reflect more accurately the development of the modern commercial turkey embryo.

Effects of modifying the World Health Organization standard operating procedures for malaria microscopy to improve surveillance in resource poor settings.

BackgroundIndividuals with fever are screened for malaria in specially-established malaria diagnostic laboratories set up in rural hospitals in the Northern and Eastern Provinces of Sri Lanka. Large numbers of blood smears negative for malaria parasites are being screened daily. Good quality smears are essential to maintain a high diagnostic competency among the technical staff. The modifications made to the World Health Organization (WHO) standard operating procedures to improve the quality of smears have been studied.MethodsA blinded, controlled, interventional study was conducted in 22 intervention and 21 control malaria diagnostic laboratories. Changes were made to the WHO standard operating procedure protocols to prepare, stain and examine blood smears for malaria parasite detection which were implemented in intervention laboratories. These included wipe-cleaning slides, preparing both thick and thin smears on the same slide, reversing the order of collecting blood for thick and thin smears, dry fixing thick smear for 20–25 minutes under table lamp, polishing the edge of spreader slide with sand paper and fixing the thin smear with methanol if not stained within four hours. Parameters with respect to quality of the smear as per WHO criteria were studied using randomly selected slides, and time taken for the report to be issued was recorded in both groups before and after the intervention.ResultsThere were no significant differences observed in the parameters studied at baseline between the two groups or pre and post intervention in the control group. In the intervention group streak formation in thin smears was reduced from 29.4% to 5.0%. The average fixing time of thick smears was reduced from 2.4 hours to 20 minutes. Inappropriate thickness of thick smears reduced from 18.3% to 1.5%. Overall quality of thick smears and thin smears increased from 76.1% to 98.0% and 81.7% to 87.0%, respectively. The quality of slides bearing both thick and thin smears increased from 60.0% to 87.0%.ConclusionsNew protocols with amendments to the WHO standard technical procedures ensure that good quality blood smears are prepared rapidly to diagnose malaria and the time required to issue the reports was reduced.

Meteorin Regulates Mesendoderm Development by Enhancing Nodal Expression

During gastrulation, distinct lineage specification into three germ layers, the mesoderm, endoderm and ectoderm, occurs through an elaborate harmony between signaling molecules along the embryonic proximo-distal and anterior-posterior axes, and Nodal signaling plays a key role in the early embryonic development governing embryonic axis formation, mesoderm and endoderm specification, and left-right asymmetry determination. However, the mechanism by which Nodal expression is regulated is largely unknown. Here, we show that Meteorin regulates Nodal expression and is required for mesendoderm development. It is highly expressed in the inner cell mass of blastocysts and further in the epiblast and extra-embryonic ectoderm during gastrulation. Genetic ablation of the Meteorin gene resulted in early embryonic lethality, presumably due to impaired lineage allocation and subsequent cell accumulation. Embryoid body culture using Meteorin-null embryonic stem (ES) cells showed reduced Nodal expression and concomitant impairment of mesendoderm specification. Meteorin-null embryos displayed reduced levels of Nodal transcripts before the gastrulation stage, and impaired expression of Goosecoid, a definitive endoderm marker, during gastrulation, while the proximo-distal and anterior-posterior axes and primitive streak formation were preserved. Our results show that Meteorin is a novel regulator of Nodal transcription and is required to maintain sufficient Nodal levels for endoderm formation, thereby providing new insights in the regulation of mesendoderm allocation.

A New Method for Proteome Screening with Two-Dimensional Urea-Sds Polyacrylamide Gel Electrophoresis

AbstractTwo-dimensional gel electrophoresis (2DE) separating proteins on the basis of their pI and molecular mass remain the best available technique for protein separation and characterization to date. But due to several limitations, including streak formation in IEF gels, partial solubility of proteins, expensive running conditions and relatively longer time taken, a simple urea-SDS-2D polyacrylamide gel electrophoresis (US2DE) is described here. The system is reasonably sensitive, cost effective with good reproducibility. The method described in this paper employs a chaotropic agent, urea, in the first dimension and sodium dodecyl sulphate (SDS), like conventional system, in the second dimension with an addition of polyacrylamide to screen the liver proteome of healthy and chemically induced fibrotic rats. The system separates the protein on the basis of chargeto- mass ratio and clearly demonstrates differential expression in the liver protein repertoire of healthy and fibrotic rats. Moreover, the present system, like other 2D electrophoretic procedures revealed at least 22 novel spots in the investigated tissues. The technique may be utilized for comprehensive proteome screening of any biological sample and would provide an overview to narrow down the candidate proteins or biomarkers.

Short periods of incubation during egg storage increase hatchability and chick quality in long-stored broiler eggs ,

It is recognized that cool egg storage for 8 d or longer, commonly employed in broiler parent and commercial layer production, reduces hatchability. In this study, we investigated the efficacy of short periods of incubation during egg storage (SPIDES) in the restoration of hatchability of broiler hatching eggs stored for 21 d. Prolonged cool storage reduced hatchability of untreated eggs from 92 to 71%. The SPIDES treatment, which consisted of four 4-h preincubations at 4- to 5-d intervals during storage, reduced the incubation time and restored hatchability to 84% by lowering both early and late embryo mortality (P = 0.0002). The SPIDES-treated embryos exhibited higher proportions of viable cells after each preincubation (P = 0.02), potentially alleviating the negative effects of storage-induced cell death on embryo development. After completion of 4 preincubations, SPIDES embryos were advanced to intermediate primitive streak formation, a developmental stage previously associated with embryo mortality during storage. In contrast to reported preincubation methods imposed on-farm immediately before the eggs are first cooled, the SPIDES technique permits 4 d of cool storage before the initial preincubation treatment, introducing flexibility in the incubation protocol and enabling cool storage up to 3 wk with much improved hatch rates than would usually be expected. Although SPIDES chicks exhibited a BW equivalent to that of embryos derived from unstored eggs at hatch, the initial relative growth was increased as a result of SPIDES, generating a higher BW over the first 4 wk posthatch (P < 0.05). Single preincubations of 6 and 12 h at 4 d of storage caused similar advances in embryo stage to the SPIDES treatment, but the hatchability was worse than in the untreated controls, suggesting small multiple preincubations during storage have a greater benefit than a single incubation performed on d 4 of storage. Future research regarding the cellular and molecular basis of physiological stress reduction in SPIDES embryos will yield new insights into the alleviation of early embryo mortality associated with egg storage.

Curcumin modulation of high fat diet-induced atherosclerosis and steatohepatosis in LDL receptor deficient mice

ObjectiveConsuming curcumin may benefit health by modulating lipid metabolism and suppressing atherogenesis. Fatty acid binding proteins (FABP-4/aP2) and CD36 expression are key factors in lipid accumulation in macrophages and foam cell formation in atherogenesis. Our earlier observations suggest that curcumin's suppression of atherogenesis might be mediated through changes in aP2 and CD36 expression in macrophages. Thus, this study aimed to further elucidate the impact of increasing doses of curcumin on modulation of these molecular mediators on high fat diet-induced atherogenesis, inflammation, and steatohepatosis in Ldlr−/− mice. MethodsLdlr−/− mice were fed low fat (LF) or high fat (HF) diet supplemented with curcumin (500 HF + LC; 1000 HF + MC; 1500 HF + HC mg/kg diet) for 16 wks. Fecal samples were analyzed for total lipid content. Lipids accumulation in THP-1 cells and expression of aP2, CD36 and lipid accumulation in peritoneal macrophages were measured. Fatty streak lesions and expression of IL-6 and MCP-1 in descending aortas were quantified. Aortic root was stained for fatty and fibrotic deposits and for the expression of aP2 and VCAM-1. Total free fatty acids, insulin, glucose, triglycerides, and cholesterol as well as several inflammatory cytokines were measured in plasma. The liver's total lipids, cholesterol, triglycerides, and HDL content were measured, and the presence of fat droplets, peri-portal fibrosis and glycogen was examined histologically. ResultsCurcumin dose-dependently reduced uptake of oxLDL in THP-1 cells. Curcumin also reduced body weight gain and body fat without affecting fat distribution. During early intervention, curcumin decreased fecal fat, but at later stages, it increased fat excretion. Curcumin at medium doses of 500–1000 mg/kg diet was effective at reducing fatty streak formation and suppressing aortic expression of IL-6 in the descending aorta and blood levels of several inflammatory cytokines, but at a higher dose (HF + HC, 1500 mg/kg diet), it had adverse effects on some of these parameters. This U-shape like trend was also present when aortic root sections were examined histologically. However, at a high dose, curcumin suppressed development of steatohepatosis, reduced fibrotic tissue, and preserved glycogen levels in liver. ConclusionCurcumin through a series of complex mechanisms, alleviated the adverse effects of high fat diet on weight gain, fatty liver development, dyslipidemia, expression of inflammatory cytokines and atherosclerosis in Ldlr−/− mouse model of human atherosclerosis. One of the mechanisms by which low dose curcumin modulates atherogenesis is through suppression of aP2 and CD36 expression in macrophages, which are the key players in atherogenesis. Overall, these effects of curcumin are dose-dependent; specifically, a medium dose of curcumin in HF diet appears to be more effective than a higher dose of curcumin.

T-Cell Immunoglobulin and Mucin Domain 3 Acts as a Negative Regulator of Atherosclerosis

Atherosclerosis is a chronic autoimmune-like disease in which lipids and fibrous elements accumulate in the arterial blood vessels. T cells are present within atherosclerotic plaques, and their activation is partially dependent on costimulatory signals, which can either provide positive or negative signals that promote T-cell activation or limit T-cell responses, respectively. T-cell immunoglobulin and mucin domain 3 (Tim-3) is a coinhibitory type 1 transmembrane protein that affects the function of several immune cells involved in atherosclerosis, such as monocytes, macrophages, effector T cells, and regulatory T cells. In the present study, we determined the role of Tim-3 in the development of atherosclerosis. Western-type diet-fed low-density lipoprotein receptor-deficient (LDLr(-/-)) mice were treated with an anti-Tim-3 antibody for 3 and 8 weeks. Anti-Tim-3 administration increased fatty streak formation with 66% and increased atherosclerotic plaque formation after 8 weeks with 35% in the aortic root and with 50% in the aortic arch. Furthermore, blockade of Tim-3 signaling increased percentages of circulating monocytes with 33% and lesional macrophages with 20%. In addition, anti-Tim-3 administration increased CD4(+) T cells with 17%, enhanced their activation status, and reduced percentages of regulatory T cells with 18% and regulatory B cells with 37%. It is known that Tim-3 acts as a negative regulator of both innate and adaptive immune responses, and in the present study, we show that anti-Tim-3 treatment augments lesion development, accompanied by an increase in the number of monocytes/macrophages and CD4(+) T cells and by decreased regulatory T cells and regulatory B cells.

How Do Elevated Triglycerides and Low HDL-Cholesterol Affect Inflammation and Atherothrombosis?

This review article summarizes recent research into the mechanisms as to how elevated levels of triglyceride (TG) and low levels of high- density- lipoprotein cholesterol (HDL-C) contribute to inflammation and atherosclerosis. Evidence supports the role of TG-rich lipoproteins in signaling mechanisms via apolipoproteins C-III and free fatty acids leading to activation of NFKβ, VCAM-1 and other inflammatory mediators which lead to fatty streak formation and advanced atherosclerosis. Moreover, the cholesterol content in TG-rich lipoproteins has been shown to predict CAD risk better than LDL-C. In addition to reverse cholesterol transport, HDL has many other cardioprotective effects which include regulating immune function. The "functionality" of HDL appears more important than the level of HDL-C. Insulin resistance and central obesity underlie the pathophysiology of elevated TG and low HDL-C in metabolic syndrome and type 2 diabetes. Lifestyle recommendations including exercise and weight loss remain first line therapy in ameliorating insulin resistance and the adverse signaling processes from elevated levels of TG-rich lipoproteins and low HDL-C.

Decoupling of amniote gastrulation and streak formation reveals a morphogenetic unity in vertebrate mesoderm induction

Mesoderm is formed during gastrulation. This process takes place at the blastopore in lower vertebrates and in the primitive streak (streak) in amniotes. The evolutionary relationship between the blastopore and the streak is unresolved, and the morphogenetic and molecular changes leading to this shift in mesoderm formation during early amniote evolution are not well understood. Using the chick model, we present evidence that the streak is dispensable for mesoderm formation in amniotes. An anamniote-like circumblastoporal mode of gastrulation can be induced in chick and three other amniote species. The induction requires cooperative activation of the FGF and Wnt pathways, and the induced mesoderm field retains anamniote-like dorsoventral patterning. We propose that the amniote streak is homologous to the blastopore in lower vertebrates and evolved from the latter in two distinct steps: an initial pan-amniote posterior restriction of mesoderm-inducing signals; and a subsequent lineage-specific morphogenetic modification of the pre-ingression epiblast.

Acetylcholine receptors regulate gene expression that is essential for primitive streak formation in murine embryoid bodies

Muscarinic acetylcholine receptors (mAchRs) are critical components of the cholinergic system, which is the key regulator of both the central and peripheral nervous systems in mammals. Interestingly, several components of the cholinergic system, including mAchRs and choline acetyltransferase (ChAT), have recently been found to be expressed in mouse embryonic stem (ES) cells and human placenta. These results raise the intriguing possibility that mAchRs play physiological roles in the regulation of early embryogenesis. Early embryogenesis can be mimicked in vitro using an ES cell-based culture system in which the cells form a primitive streak-like structure and efficiently develop into mesodermal progenitors. Here we report that chemical inhibitors specifically targeting mAchRs suppressed the expression of genes essential for primitive streak formation, including Wnt3, and thereby blocked mesodermal progenitor differentiation. Interestingly, mAchR inhibitors also reduced the expression of Cyp26a1, an enzyme involved in the catabolism of retinoic acid (RA). RA is an important regulator of Wnt3 signaling. Our study presents evidence indicating that mAchRs influence RA signaling necessary for the induction of the primitive streak. To our knowledge, this is the first report showing that mAchRs have important functions not only in adult mammals but also during early mammalian embryogenesis.

Abstract 463: TLT-1 Deficiency Affects Hypercholesterolemia and Progression of the Atherosclerotic Plaque in Apoe Null Mice

Platelet activation at sites of inflammation triggers the secretion of molecules that induce the transition of atherosclerosis from fatty streak to an acute disease, featuring an increased vulnerability of the atherosclerotic lesion that results in plaque rupture and thrombosis. TLT-1 (Triggering Receptor Expressed in Myeloid cells (TREM)-like transcript-1) is a molecule exclusively found in the α-granules of megakarocytes and platelets and has a demonstrated effect in inflammatory responses. Upon platelet activation, TLT-1 is moved to the platelet surface, while its soluble form, s-TLT-1, is secreted and detected in serum. Studies using the C57Bl/6 treml1 - /- mouse demonstrated a predisposition to hemorrhage after an acute inflammatory challenge suggesting that TLT-1 may be a key regulatory molecule in the interface between hemostatic and inflammatory mechanisms. Because we have found that sTLT-1 levels are significantly elevated in apoE mice when compared to wild type, we hypothesized that TLT-1 may be playing an important role in the progression of atherosclerosis. To address this possibility, we generated apoE - /- / treml1 - /- double knockout mice [DN]. Assessment of lesions after 4 weeks high-fat diet (HFD) demonstrated that at early stages, TLT-1 deficiency accelerates fatty streak formation. After 20 weeks on HFD, lesions in both apoE - /- and [DN] mice progressed to an advance fibrous plaque stage. Although their lesion sizes were not substantially different, lesion compositions were. The mechanistic basis of these differences appears to be that the [DN] mice have significantly higher cholesterol levels when compared to apoE - /- mice. The increased cholesterol levels extend to the treml1 -/- mouse when compared to wild type mice at 4 weeks on HFD, this difference, however, gradually subsides as wild type mice cholesterol levels increase over 20 weeks. Interestingly, cholesterol levels in 50 week old mice on chow diet revealed minimal differences between test and control mice suggesting the higher cholesterol levels are related to increased dietary intake. Our work defines a surprising role for TLT-1 in the regulation of serum cholesterol levels during atherogenesis.

Microstructure Investigations of Streak Formation in 6063 Aluminum Extrusions by Optical Metallographic Techniques

The present study investigates the effect of the solidification strategy for AA 6063 alloy on the surface appearance of anodized extrusions. The microstructure of the samples was analyzed using both light optical microscopy and scanning electron microscopy. Results show that if heavy segregation occurs from rapid solidification, coarse Mg2Si particles form, thus reducing the potential for precipitation strengthening by the finer β-Mg2Si developed in the solid state. Differentially-strained regions formed during hot extrusion induce differences in particle size for magnesium silicide (Mg2Si) precipitates. Anodizing generates surface roughness due to Mg2Si particle dissolution and AlFeSi decohesion, which is related to both particle size and deformation. During anodizing, an oxide layer forms on the surface of the extruded products, which can lead to streak formation, usually a subject of rejection due to unacceptable heterogeneous reflectivity.

Arginase inhibition by piceatannol-3′-O-β-D-glucopyranoside improves endothelial dysfunction via activation of endothelial nitric oxide synthase in ApoE-null mice fed a high-cholesterol diet

Elevated plasma cholesterol is a hallmark of numerous cardiovascular diseases that are closely linked to endothelial dysfunction indicating decreased nitric oxide (NO) production in the endothelium. It has been previously demonstrated that piceatannol-3'-O-β-D-glucopyranoside (PG) inhibits arginase activity and reciprocally regulates NO production. Here, we aimed to ascertain whether PG ameliorates vascular function in wild-type (WT) and atherogenic model mice [apolipoprotein E-null mice (ApoE-/-)] and to investigate the possible underlying mechanism. Preincubation of aortic vessels from WT mice fed a normal diet (ND) with PG attenuated vasoconstriction response to U46619 and phenylephrine (PE), while the vasorelaxant response to acetylcholine (Ach) was markedly enhanced in an endothelium-dependent manner. However, the endothelium-independent NO donor, sodium nitroprusside (SNP), did not change vessel reactivity. In thoracic aorta from ApoE-/- mice, a high-cholesterol diet (HCD) induced an increase in arginase activity, a decrease in NO release and an increase in reactive oxygen species generation that was reversed by treatment with PG. The effect of PG was associated with enhanced stability of the eNOS dimer and was not dependent on the expression levels of arginase II and eNOS proteins, although eNOS expression was increased in ApoE-/- mice fed an HCD. Furthermore, PG treatment attenuated the PE-dependent contractile response, and significantly improved the Ach-dependent vasorelaxation response in aortic rings from ApoE-/- mice fed an HCD. On the other hand, PG incubation neither altered the contractile response to a high K+ solution nor the relaxation response to SNP. When analyzing the L-arginine content using high-performance liquid chromatography, PG incubation increased the intracellular L-arginine concentration. PG administration in the drinking water significantly reduced fatty streak formation in ApoE-/- mice fed an HCD. These data indicate that PG improves the pathophysiology of cholesterol-mediated endothelial dysfunction. Therefore, we conclude that the development of PG as a novel effective therapy for preventing atherosclerotic diseases is warranted.

NO–β-catenin crosstalk modulates primitive streak formation prior to embryonic stem cell osteogenic differentiation

Nitric oxide (NO) has been shown to play a crucial role in bone formation in vivo. We sought to determine the temporal effect of NO on murine embryonic stem cells (ESCs) under culture conditions that promote osteogenesis. Expression profiles of NO pathway members and osteoblast-specific markers were analyzed using appropriate assays. We found that NO was supportive of osteogenesis specifically during an early phase of in vitro development (days 3-5). Furthermore, ESCs stably overexpressing the inducible NO synthase showed accelerated and enhanced osteogenesis in vitro and in bone explant cultures. To determine the role of NO in early lineage commitment, a stage in ESC differentiation equivalent to primitive streak formation in vivo, ESCs were transfected with a T-brachyury-GFP reporter. Expression levels of T-brachyury and one of its upstream regulators, β-catenin, the major effector in the canonical Wnt pathway, were responsive to NO levels in differentiating primitive streak-like cells. Our results indicate that NO may be involved in early differentiation through regulation of β-catenin and T-brachyury, controlling the specification of primitive-streak-like cells, which may continue through differentiation to later become osteoblasts.

Nonlinear optimal perturbations in a Couette flow: bursting and transition

AbstractThis paper provides the analysis of bursting and transition to turbulence in a Couette flow, based on the growth of nonlinear optimal disturbances. We use a global variational procedure to identify such optimal disturbances, defined as those initial perturbations yielding the largest energy growth at a given target time, for given Reynolds number and initial energy. The nonlinear optimal disturbances are found to be characterized by a basic structure, composed of inclined streamwise vortices along localized regions of low and high momentum. This basic structure closely recalls that found in boundary-layer flow (Cherubini et al., J. Fluid Mech., vol. 689, 2011, pp. 221–253), indicating that this structure may be considered the most ‘energetic’ one at short target times. However, small differences in the shape of these optimal perturbations, due to different levels of the initial energy or target time assigned in the optimization process, may produce remarkable differences in their evolution towards turbulence. In particular, direct numerical simulations have shown that optimal disturbances obtained for large initial energies and target times induce bursting events, whereas for lower values of these parameters the flow is directly attracted towards the turbulent state. For this reason, the optimal disturbances have been classified into two classes, the highly dissipative and the short-path perturbations. Both classes lead the flow to turbulence, skipping the phases of streak formation and secondary instability which are typical of the classical transition scenario for shear flows. The dynamics of this transition scenario exploits three main features of the nonlinear optimal disturbances: (i) the large initial value of the streamwise velocity component; (ii) the streamwise dependence of the disturbance; (iii) the presence of initial inclined streamwise vortices. The short-path perturbations are found to spend a considerable amount of time in the vicinity of the edge state (Schneider et al., Phys. Rev. E, vol. 78, 2008, 037301), whereas the highly dissipative optimal disturbances pass closer to the edge, but they are rapidly repelled away from it, leading the flow to high values of the dissipation rate. After this dissipation peak, the trajectories do not lead towards the turbulent attractor, but they spend some time in the vicinity of an unstable periodic orbit (UPO). This behaviour led us to conjecture that bursting events can be obtained not only as homoclinic orbits approaching the UPO, as recently found by van Veen &amp; Kawahara (Phys. Rev. Lett., vol. 107, 2011, p. 114501), but also as heteroclinic orbits between the equilibrium solution on the edge and the UPO.

The Last Contribution of Hemophiliacs to Blood Coagulation: Atherosclerosis Is Not Prevented by Hypocoagulability

“In principio omnes errant hemophiliacs”. In the past, all bleeding patients were considered as hemophiliacs. Quick demonstrated in the mid thirties that hemophiliacs had a normal prothrombin time (P.T.). This allowed the first distinction of “bleeding patients” in two groups, some with a normal P.T. and some with a prolonged P.T. [1]. Only in 1947, “hemophilia” could be suspected to comprise two different diseases, when Pawlowski in Argentina showed the correction of the defect after mixing the plasmas of two patients known to have hemophilia, thereby suggesting the existence of two types of defect [2]. This was independently confirmed later on by Aggeler et al in the U.S.A. and in England by the Oxford Group in 1952 [3, 4]. Since that time the contribution of hemophilic patients to the understanding of blood coagulation was astonishing and could be summarized along the following lines, without the presumption to be complete: 1). Cryoprecipitates corrected Hemophilia A but not, or very little the hemophilia B defect [5]. 2). Immunological studies on hemophilia A and B have opened new horizons on VWD and demonstrated the existence of hemophilia variants with cross reacting material (CRM) [6, 7]. These studies were then instrumental in the classification of other clotting defects, especially, FX and F VII defects [8]. 3). A hemophilia B variant, hemophilia BM, showed a prolonged prothrombin time when a reagent containing ox-brain thomboplastin was used in the assay system [9]. This opened new horizons in prothrombin complex diseases with regard to their reactivity towards tissue thromploplastins of different origin [10]. 4). Another peculiar contribution was the observation that, in a special type of hemophilia B (Hemophilia B Leyden) there was a variable correction of the defect as the patients aged [11]. This cast light on the androgen-dependent maturation of FIX at the hepatocyte level. 5). Hemophilia patients payed heavily for our delays and faults in the developing of safe concentrates. The pain, sacrifice and the size of the cemetery of hemophiliacs has still to be properly acknowledged and described. 6). Synoviectomy carried out in hemophiliacs in an attempt to impede or delay the occurrence of the arthropathy has considerably spurred the use of this procedure in several orthopedic diseases [12]. 7). The development in some patients of antibodies after replacement therapy has opened important lines of investigation in the genetic control of immunological mechanisms. 8). The widespread treatment of HIV and hepatitis B and C in hemophilia patients has supplied valuable information for the management of these infections even in non-bleeding subjects. 9). The role of liver transplantation in the management of hemophilia is still disputed. However some success has been obtained even by the live donor transplant [13-15]. 10). The status of genetic therapy of hemophilia is still open and very controversial but hemophiliacs have given a contribution even to this field [16, 17]. They represent, at least on theoretical grounds, ideal subjects for gene therapy [16]. Now, hemophiliacs supply us with a new important information. They have shown that atherosclerosis’ may occur in them as in normal persons [18, 19]. Old studies had suggested that the clotting defect could exercise a protection against atherosclerosis. They were wrong. Now it is known that this is not the case. A new medical field has been opened. How to treat hemophilia patients with atherosclerosis and its complications, notably acute coronary syndromes. So, after so many contributions, another major contribution has emerged. Thanks to the improved overall care and to the safety of replacement therapy, the hemophilia population has aged and with age , age related problems have appeared [19, 20]. The demonstration that atherosclerosis may occur in patients with hemophilia and with other congenital coagulation disorders is an event of great importance in blood coagulation. It indicates that hypocoagulability does not prevent the aging of the arteries, namely the formation of fatty streaks or plaques in the intima of the arteries. The focus on the pathogenesis of atherosclerosis must rest therefore on lipids (mainly cholesterol) and inflammation. Congenital hypocoagulability may still protect from atherothrombosis which refers to the formation of a thrombus on fissured on ulcerated plaques. However an arterial occlusion may occur without the formation of a thrombus. This may explain at least part of the myocardial infarctions (M.I.) seen in patients with Hemophilia and other clotting disorders. Autopsy and coronographic data indicate that atherosclerotic streaks and plaques are always present, sometimes complicated by the formation of a thrombus [21, 22]. Manuscript accepted for publication May 27, 2013

Nigella sativa L. improves lipid profile and prevents atherosclerosis: Evidence from an experimental study on hypercholesterolemic rabbits

The effects of Nigella sativa (NS) on lipid profile, C-reactive protein, oxidized LDL, antioxidant capacity, Apo A and Apo B and fatty streak formation in hypercholesterolemic male rabbits were examined. Fifteen rabbits were distributed into three groups of five each [normal diet, hypercholesterolemic diet (1% cholesterol) and hypercholesterolemic diet (1% cholesterol) supplemented with 5% NS]. They received rabbit laboratory chow diet for a period of 8weeks. At the start and end of the study, fasting blood was taken from all animals. NS significantly decreased fatty streak formation as well as total cholesterol (TC) and low-density lipoprotein (LDL) in hypercholesterolemic male rabbits. NS showed positive effects on other factors (triacylglycerol, high-density lipoprotein, C-reactive protein, oxidized LDL, antioxidant capacity, Apo A and Apo B), but these were insignificant. Based on favorable efficiency of NS on TC and LDL reduction and its anti-atherogenic cardioprotective properties, it is suggested using this plant with fat-rich diets simultaneously may reduce their adverse health effects.

Infrared imagery of streak formation in a breaking wave

High resolution infrared imagery of breaking waves in a wave-tank free of wind shear or current reveals the production of a “streaky,” quasi-periodic thermal pattern produced during the breaking process. The streaks, or elongated patterns of warm and cold fluid, are found to form only when surface turbulence is present before wave breaking occurs. This suggests that wave-turbulence interaction is one mechanism that can lead to streak formation in breaking wave systems. More specifically, the streaky structures observed in these experiments may be caused by an intense, rapid tilting, and stretching of pre-existing vertical vorticity by the Stokes drift generated at or near the breaking wave crests, thereby generating a coherent system of counter-rotating vortices. We attempt to relate our observations to the recent theory of Teixeira and Belcher [J. Fluid Mech. 458, 229–267 (2002)10.1017/S0022112002007838]. Some properties of the streaks, such as the dependence of their lifetimes and spanwise scale on wave amplitude, are presented.