Mechanotransduction in response to shear stress. Roles of receptor tyrosine kinases, integrins, and Shc

Shear stress, the tangential component of hemodynamic forces, activates many signal transduction pathways in vascular endothelial cells. The conversion of mechanical stimulation into chemical signals is still unclear. We report here that shear stress (12 dynes/cm2) induced a rapid and transient tyrosine phosphorylation of Flk-1 and its concomitant association with the adaptor protein Shc; these are accompanied by a concurrent clustering of Flk-1, as demonstrated by confocal microscopy. Our results also show that shear stress induced an association of alphavbeta3 and beta1 integrins with Shc, and an attendant association of Shc with Grb2. These associations are sustained, in contrast to the transient Flk-1. Shc association in response to shear stress and the transient association between alphavbeta3 integrin and Shc caused by cell attachment to substratum. Shc-SH2, an expression plasmid encoding the SH2 domain of Shc, attenuated shear stress activation of extracellular signal-regulated kinases and c-Jun N-terminal kinases, and the gene transcription mediated by the activator protein-1/12-O-tetradecanoylphorbol-13-acetate-responsive element complex. Our results indicate that receptor tyrosine kinases and integrins can serve as mechanosensors to transduce mechanical stimuli into chemical signals via their association with Shc.

Action of molecular switches in GPCRs--theoretical and experimental studies

G protein coupled receptors (GPCRs), also called 7TM receptors, form a huge superfamily of membrane proteins that, upon activation by extracellular agonists, pass the signal to the cell interior. Ligands can bind either to extracellular N-terminus and loops (e.g. glutamate receptors) or to the binding site within transmembrane helices (Rhodopsin-like family). They are all activated by agonists although a spontaneous auto-activation of an empty receptor can also be observed. Biochemical and crystallographic methods together with molecular dynamics simulations and other theoretical techniques provided models of the receptor activation based on the action of so-called "molecular switches" buried in the receptor structure. They are changed by agonists but also by inverse agonists evoking an ensemble of activation states leading toward different activation pathways. Switches discovered so far include the ionic lock switch, the 3-7 lock switch, the tyrosine toggle switch linked with the nPxxy motif in TM7, and the transmission switch. The latter one was proposed instead of the tryptophan rotamer toggle switch because no change of the rotamer was observed in structures of activated receptors. The global toggle switch suggested earlier consisting of a vertical rigid motion of TM6, seems also to be implausible based on the recent crystal structures of GPCRs with agonists. Theoretical and experimental methods (crystallography, NMR, specific spectroscopic methods like FRET/BRET but also single-molecule-force-spectroscopy) are currently used to study the effect of ligands on the receptor structure, location of stable structural segments/domains of GPCRs, and to answer the still open question on how ligands are binding: either via ensemble of conformational receptor states or rather via induced fit mechanisms. On the other hand the structural investigations of homoand heterodimers and higher oligomers revealed the mechanism of allosteric signal transmission and receptor activation that could lead to design highly effective and selective allosteric or ago-allosteric drugs.

Response of the pulmonary vasculature to hypoxia and H+ ion concentration changes

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Molecular mechanism of endothelial growth arrest by laminar shear stress

This study was designed to elucidate the mechanism underlying the inhibition of endothelial cell growth by laminar shear stress. Tumor suppressor gene p53 was increased in bovine aortic endothelial cells subjected to 24 h of laminar shear stress at 3 dynes (1 dyne = 10 microN)/cm(2) or higher, but not at 1.5 dynes/cm(2). One of the mechanisms of the shear-induced increase in p53 is its stabilization after phosphorylation by c-Jun N-terminal kinase. To investigate the consequence of the shear-induced p53 response, we found that prolonged laminar shear stress caused increases of the growth arrest proteins GADD45 (growth arrest and DNA damage inducible protein 45) and p21(cip1), as well as a decrease in phosphorylation of the retinoblastoma gene product. Our results suggest that prolonged laminar shear stress causes a sustained p53 activation, which induces the up-regulation of GADD45 and p21(cip1). The resulting inhibition of cyclin-dependent kinase and hypophosphorylation of retinoblastoma protein lead to endothelial cell cycle arrest. This inhibition of endothelial cell proliferation by laminar shear stress may serve an important homeostatic function by preventing atherogenesis in the straight part of the arterial tree that is constantly subjected to high levels of laminar shearing.

Identification of a new fibroblast growth factor receptor, FGFR5

A novel fibroblast growth factor receptor (FGFR), designated FGFR5, was identified from an EST database of a murine lymph node stromal cell cDNA library. The EST has approximately 32% identity to the extracellular domain of FGFR1-4. Library screening with this EST identified two full-length alternative transcripts which we designated as FGFR5 beta and FGFR5 gamma. The main difference between these transcripts is that FGFR5 beta contains three extracellular Ig domains whereas FGFR5 gamma contains only two. A unique feature of FGFR5 is that it does not contain an intracellular tyrosine kinase domain. Predictive structural modelling of the extracellular domain of FGFR5 gamma suggested that it was a member of the I-set subgroup of the Ig-superfamily, consistent with the known FGFRs. Northern analysis of mouse and human FGFR5 showed detectable mRNA in a broad range of tissues, including kidney, brain and lung. Genomic sequencing identified four introns but identified no alternative transcripts containing a tyrosine kinase domain. Extracellular regions of FGFR5 beta and 5 gamma were cloned in-frame with the Fc fragment of human IgG(1) to generate recombinant non-membrane bound protein. Recombinant FGFR5 beta Fc and R5 gamma Fc demonstrated specific binding to the ligand FGF-2, but not FGF-7 or EGF. However, biological data suggest that FGF-2 binding to these proteins is with lower affinity than its cognate receptor FGFR2C. The above data indicate that this receptor should be considered as the fifth member of the FGFR family.

Therapeutic hypercapnia reduces pulmonary and systemic injury following in vivo lung reperfusion

Permissive hypercapnia, involving tolerance to elevated Pa(CO(2)), is associated with reduced acute lung injury (ALI), thought to result from reduced mechanical stretch, and improved outcome in ARDS. However, deliberately elevating inspired CO(2) concentration alone (therapeutic hypercapnia, TH) protects against ALI in ex vivo models. We investigated whether TH would protect against ALI in an in vivo model of lung ischemia-reperfusion (IR). Anesthetized open chest rabbits were ventilated (standard eucapnic settings), and were randomized to TH (FI(CO(2)) 0.12) versus control (FI(CO(2)) 0.00). Pa(CO(2)) and arterial pH values achieved in the TH versus CON groups were 101 +/- 3 versus 44.4 +/- 4 mm Hg and 7.10 +/- 0.03 versus 7.37 +/- 0.03, respectively. Following left lung ischemia and reperfusion, TH versus control was associated with preservation of lung mechanics, attenuation of protein leakage, reduction in pulmonary edema, and improved oxygenation. Indices of systemic protection included improved acid-base and lactate profile, in the absence of systemic hypoxemia. In the TH group, mean BALF TNF-alpha levels were 3.5% of CON levels (p < 0.01), and mean 8-isoprostane levels were 30% of CON levels (p = 0.02). Western blot analysis demonstrated reduced lung tissue nitrotyrosine in TH, indicating attenuation of tissue nitration. Finally, preliminary data suggest that TH may attenuate apoptosis following lung IR. We conclude that in the current model TH is protective versus IR lung injury and mechanisms of protection include preservation of lung mechanics, attenuation of pulmonary inflammation, and reduction of free radical mediated injury. If these findings are confirmed in additional models, TH may become a candidate for clinical testing in critical care.

Shear stress activates p60src-Ras-MAPK signaling pathways in vascular endothelial cells

The aim of this study was to elucidate the upstream signaling mechanism that mediates the fluid shear stress activation of mitogen-activated protein kinases (MAPKs), including c-Jun NH2-terminal kinase (JNK) and extracellular signal-regulated kinases (ERKs), in vascular endothelial cells (ECs). Our results indicate that p60src is rapidly activated by fluid shear stress in bovine aortic endothelial cells (BAECs). Shear stress induction of the hemagglutinin (HA) epitope-tagged HA-JNK1 and the Myc epitope-tagged Myc-ERK2 was significantly attenuated by v-src(K295R) and c-src(K295R), the kinase-defective mutants ofv-src and c-src, respectively. HA-JNK1 and Myc-ERK2 were activated by c-src(F527), a constitutively activated form of p60src, and the activation was abolished by RasN17, a dominant-negative mutant of p2lras. In contrast, although HA-JNK1 and Myc-ERK2 were also activated by RasL61, an activated form of p21ras, the activation was not affected by v-src(K295R). These results indicate that p60src is upstream to the Ras-JNK and Ras-ERK pathways in response to shear stress. The shear stress inductions of the promoters of monocyte chemotactic protein-1 (MCP-1) and c-fos, driven by TPA-responsive element (TRE) and serum-responsive element (SRE), respectively, were attenuated by v-src(K295R). This attenuation is associated with decreased transcriptional activities of c-Jun and Elk-1, the transcription factors targeting TRE and SRE, respectively. Thus, p60src plays a critical role in the shear stress activation of MAPK pathways and induction of Activating Protein-1 (AP- 1)/TRE and Elk-1/SRE-mediated transcription in ECs.

DNA microarray analysis of gene expression in endothelial cells in response to 24-h shear stress

The recently developed DNA microarray technology provides a powerful and efficient tool to rapidly compare the differential expression of a large number of genes. Using the DNA microarray approach, we investigated gene expression profiles in cultured human aortic endothelial cells (HAECs) in response to 24 h of laminar shear stress at 12 dyn/cm(2). This relatively long-term shearing of cultured HAECs led to the modulation of the expression of a number of genes. Several genes related to inflammation and EC proliferation were downregulated, suggesting that 24-h shearing may keep ECs in a relatively noninflammatory and nonproliferative state compared with static cells. Some genes were significantly upregulated by the 24-h shear stress; these includes genes involved in EC survival and angiogenesis (Tie2 and Flk-1) and vascular remodeling (matrix metalloproteinase 1). These results provide information on the profile of gene expression in shear-adapted ECs, which is the case for the native ECs in the straight part of the aorta in vivo.

Pancreatic islet cell survival following islet isolation: the role of cellular interactions in the pancreas

The purpose of this study was to characterize the trophic effect of pancreatic duct cells on the islets of Langerhans. Ductal epithelium and islets were isolated from hamster pancreata. In addition, duct-conditioned medium (DCM) was prepared from primary duct cultures that had been passaged twice to remove other cellular elements. Three experimental groups were then established: Group 1, 100 islets alone; Group 2, 100 islets+80 duct fragments; and Group 3, 100 islets in 25% DCM. All tissues were embedded in rat tail collagen for up to 12 days and the influence of pancreatic ductal epithelium on islet cell survival was examined. By day 12, 20.6+/-3. 0% (S.E.M.) of the islets cultured alone developed central necrosis, compared with 6.7+/-2.0% of the islets co-cultured with ducts and 5.6+/-1.5% of the islets cultured in DCM (P<0.05). The presence of apoptotic cell death was determined by a TdT-mediated dUTP-biotin nick end labelling (TUNEL) assay and by a specific cell death ELISA. DNA fragmentation in islets cultured alone was significantly increased compared with islets cultured either in the presence of duct epithelium or in DCM (P<0.05). More than 80% of TUNEL-positive cells were situated in the inner 80% of the islet area, suggesting that most were beta-cells. DCM was analysed for known growth factors. The presence of a large amount of IGF-II (34 ng/ml) and a much smaller quantity of nerve growth factor (4 ng/ml) was identified. When the apoptosis studies were repeated to compare islets alone, islets+DCM and islets+IGF-II, the cell death ELISA indicated that IGF-II produced the same beneficial result as DCM when compared with islets cultured alone. We conclude that pancreatic ductal epithelium promotes islet cell survival. This effect appears to be mediated in a paracrine manner by the release of IGF-II from cells in the ductal epithelium.

Adenovirus-based vaccines: comparison of vectors from three species of adenoviridae

In order to better understand the broad applicability of adenovirus (Ad) as a vector for human vaccine studies, we compared four adenovirus (Ad) vectors from families C (Ad human serotype 5 [HAdV-5; here referred to as AdHu5]), D (HAdV-26; here referred to as AdHu26), and E (simian serotypes SAdV-23 and SAdV-24; here referred to as chimpanzee serotypes 6 and 7 [AdC6 and AdC7, respectively]) of the Adenoviridae. Seroprevalence rates and titers of neutralizing antibodies to the two human-origin Ads were found to be higher than those reported previously, especially in countries of sub-Saharan Africa. Conversely, prevalence rates and titers to AdC6 and AdC7 were markedly lower. Healthy human adults from the United States had readily detectable circulating T cells recognizing Ad viruses, the levels of which in some individuals were unexpectedly high in response to AdHu26. The magnitude of T-cell responses to AdHu5 correlated with those to AdHu26, suggesting T-cell recognition of conserved epitopes. In mice, all of the different Ad vectors induced CD8(+) T-cell responses that were comparable in their magnitudes and cytokine production profiles. Prime-boost regimens comparing different combinations of Ad vectors failed to indicate that the sequential use of Ad vectors from distinct families resulted in higher immune responses than the use of serologically distinct Ad vectors from the same family. Moreover, the transgene product-specific antibody responses induced by the AdHu26 and AdC vectors were markedly lower than those induced by the AdHu5 vector. AdHu26 vectors and, to a lesser extent, AdC vectors induced more potent Ad-neutralizing antibody responses. These results suggest that the potential of AdHu26 as a vaccine vector may suffer from limitations similar to those found for vectors based on other prevalent human Ads.

Berberine Ameliorates Periodontal Bone Loss by Regulating Gut Microbiota

Postmenopausal osteoporosis (PMO) is a risk factor for periodontitis, and current therapeutics against PMO prevent the aggravated alveolar bone loss of periodontitis in estrogen-deficient women. Gut microbiota is recognized as a promising therapeutic target for PMO. Berberine extracted from Chinese medicinal plants has shown its effectiveness in the treatment of metabolic diseases such as obesity and diabetes via regulating gut microbiota. Here, we hypothesize that berberine ameliorates periodontal bone loss by improving the intestinal barriers by regulating gut microbiota under an estrogen-deficient condition. Experimental periodontitis was established in ovariectomized (OVX) rats, and the OVX-periodontitis rats were treated with berberine for 7 wk before sacrifice for analyses. Micro–computed tomography and histologic analyses showed that berberine treatment significantly reduced alveolar bone loss and improved bone metabolism of OVX-periodontitis rats as compared with the vehicle-treated OVX-periodontitis rats. In parallel, berberine-treated OVX-periodontitis rats harbored a higher abundance of butyrate-producing gut microbiota with elevated butyrate generation, as demonstrated by 16S rRNA sequencing and high-performance liquid chromatography analysis. Berberine-treated OVX-periodontitis rats consistently showed improved intestinal barrier integrity and decreased intestinal paracellular permeability with a lower level of serum endotoxin. In parallel, IL-17A-related immune responses were attenuated in berberine-treated OVX-periodontitis rats with a lower serum level of proinflammatory cytokines and reduced IL-17A+ cells in alveolar bone as compared with vehicle-treated OVX-periodontitis rats. Our data indicate that gut microbiota is a potential target for the treatment of estrogen deficiency–aggravated periodontal bone loss, and berberine represents a promising adjuvant therapeutic by modulating gut microbiota.

Transdifferentiation of human islets to pancreatic ductal cells in collagen matrix culture

Transdifferentiation is a change from one differentiated phenotype to another, involving morphological and functional phenotypic markers. Stability of the cellular phenotype is probably related to the extracellular milieu, as well as cytoplasmic and nuclear components that interact to control gene expression, and the conversion of cell phenotype is likely to be accomplished by selective enhancement of gene expression, which controls the terminal developmental commitment of cells. In this paper, we show the induction of cultured human islets cells to alter their usual phenotypic expression and attain morphological and functional characteristics of duct cells. Islets were isolated by collagenase digestion of pancreata that were removed from cadaveric organ donors. The islets were purified on a two-step density gradient of bovine serum albumin and were then placed into a three-dimensional rat-tail collagen gel matrix supplemented with NuSerum epithelial growth factor and cholera toxin. During the initial 96 h of culture, the islets underwent a cystic transformation that was associated with (1) the maintenance of immunoreactivity for neuron-specific enolase, an endocrine cell marker, but a progressive loss of insulin gene expression, (2) a loss of immunoreactivity for insulin protein, and (3) the appearance of CK-19, a marker for ductal cells. After the transformation was complete, the cells had the ultrastructural appearance of primitive duct-like cells. Cyst enlargement after the initial 96 h was associated, at least in part, with cell replication, as reflected in the 1500% increase in the incorporation of tritiated thymidine. These experiments are consistent with the transdifferentiation of an islet cell to a ductal cell. The exact mechanisms involved still need to be fully elucidated.

Retinoid signaling required for normal heart development regulates GATA-4 in a pathway distinct from cardiomyocyte differentiation

Vitamin A is essential for normal embryonic cardiogenesis. The vitamin A-deficient phenotype in the avian embryo includes an abnormal heart tube closed at the sinus venosus and the absence of large vessels that normally connect the embryonic heart to the developing circulatory system. In vitamin A-deficient embryos the expression of cardiomyocyte differentiation genes, including atrial-specific myosin heavy chain, ventricular-specific myosin, and sarcomeric myosins as well as the putative cardiomyocyte specification gene Nkx-2.5, is not altered. However, the expression of transcription factor GATA-4 is severely decreased in the heart-forming regions of vitamin A-deficient stage 7-10 embryos. Significantly, GATA-4 transcripts are completely lacking in the lateral mesoderm posterior to the heart, in the area of the developing cardiac inflow tract that later displays prominent morphological defects, including a closed nonseptated heart lacking a sinus venosus. The administration of retinol to the vitamin A-deficient embryo restores GATA-4 expression and completely rescues the vitamin A-deficient phenotype. Our results indicate that GATA-4 is a component of the retinoid-mediated cardiogenic pathway unlinked to cardiomyocyte differentiation, but involved in the morphogenesis of the posterior heart tube and the development of the cardiac inflow tract.

A protective role for periostin and TGF-β in IgE-mediated allergy and airway hyperresponsiveness

Background

The pathophysiology of asthma involves allergic inflammation and remodelling in the airway and airway hyperresponsiveness (AHR) to cholinergic stimuli, but many details of the specific underlying cellular and molecular mechanisms remain unknown. Periostin is a matricellular protein with roles in tissue repair following injury in both the skin and heart. It has recently been shown to be up-regulated in the airway epithelium of asthmatics and to increase active TGF-β. Though one might expect periostin to play a deleterious role in asthma pathogenesis, to date its biological role in the airway is unknown.

Objective

To determine the effect of periostin deficiency on airway responses to inhaled allergen.

Methods

In vivo measures of airway responsiveness, inflammation, and remodelling were made in periostin deficient mice and wild-type controls following repeated intranasal challenge with Aspergillus fumigatus antigen. In vitro studies of the effects of epithelial cell-derived periostin on murine T cells were also performed.

Results

Surprisingly, compared with wild-type controls, periostin deficient mice developed increased AHR and serum IgE levels following allergen challenge without differences in two outcomes of airway remodelling (mucus metaplasia and peribronchial fibrosis). These changes were associated with decreased expression of TGF-β1 and Foxp3 in the lungs of periostin deficient mice. Airway epithelial cell-derived periostin-induced conversion of CD4⁺ CD25⁻ cells into CD25⁺, Foxp3⁺ T cells in vitro in a TGF-β dependent manner.

Conclusions and Clinical Relevance

Allergen-induced increases in serum IgE and bronchial hyperresponsiveness are exaggerated in periostin deficient mice challenged with inhaled aeroallergen. The mechanism of periostin's effect as a brake on allergen-induced responses may involve augmentation of TGF-β-induced T regulatory cell differentiation.

Immunization with heat-killed Mycobacterium vaccae stimulates CD8+ cytotoxic T cells specific for macrophages infected with Mycobacterium tuberculosis

Immune responses to Mycobacterium tuberculosis are analyzed in mice which have been immunized with Mycobacterium vaccae to examine novel ways of altering protective immunity against M. tuberculosis. The spleen cells of mice immunized with M. vaccae proliferate and secrete gamma interferon (IFN-gamma) in response to challenge with live M. tuberculosis in vitro. Immunization with M. vaccae results in the generation of CD8+ T cells which kill syngeneic macrophages infected with M. tuberculosis. These effector cytotoxic T cells (CTL) are detectable in the spleen at 2 weeks after immunization with M. vaccae but cannot be found in splenocytes 3 to 6 weeks postimmunization. However, M. tuberculosis-specific CTL are revealed following restimulation in vitro with heat-killed M. vaccae or M. tuberculosis, consistent with the activation of memory cells. These CD8+ T cells secrete IFN-gamma and enhance the production of interleukin 12 when cocultured with M. tuberculosis-infected macrophages. It is suggested that CD8+ T cells with a cytokine secretion profile of the Tc1 class may themselves maintain the dominance of a Th1-type cytokine response following immunization with M. vaccae. Heat-killed M. vaccae deserves attention as an alternative to attenuated live mycobacterial vaccines.

Resonant scattering by realistic impurities in graphene

We develop a first-principles theory of resonant impurities in graphene and show that a broad range of typical realistic impurities leads to the characteristic sublinear dependence of the conductivity on the carrier concentration. By means of density functional calculations various organic groups as well as adatoms such as H absorbed to graphene are shown to create midgap states within ±0.03  eV around the neutrality point. A low energy tight-binding description is mapped out. Boltzmann transport theory as well as a numerically exact Kubo formula approach yield the conductivity of graphene contaminated with these realistic impurities in accordance with recent experiments.

Multiple cis-elements mediate shear stress-induced gene expression

Fluid shear stress activates the expression of immediate early (IE) genes in vascular endothelial cells. The transcriptional regulation can be mediated through the shear stress-sensitive cis-acting elements at the 5' promoter regions of various IE genes such as the monocyte chemotactic protein-1 (MCP-1) gene. We linked wild-type and mutated MCP-1 promoters to the reporter gene luciferase and used such constructs to investigate the role of the phorbol ester TPA responsive element (TRE) in the shear-induced MCP-1 gene expression in vascular endothelial cells. Functional analysis showed that TGACTCC (a divergent TRE) located at nt -54 to -60 is necessary for shear-inducibility in bovine aortic endothelial cells (BAEC). The induction of the wild-type MCP-1 promoter construct by shear stress was attenuated by pretreating the cells with 1 microM dexamethasone or 1 microM retinoic acid 12 h before the shear stress experiments. The induction by shear stress reduced from 13-fold in the untreated cells to 7- and 3-folds in the dexamethasone- and retinoic acid-treated cells, respectively. These results demonstrate that the glucocorticoid receptor and retinoic acid receptor may interfere with the shear stress-activated AP-1/TRE. The reporter activity of HIV(LTR), which is a plasmid construct of the long terminal repeats of the human immunodeficiency virus and contains a kappa B enhancer element, was also activated by shear stress. The results of our investigations indicate that the shear stress-induced IE gene expression can be mediated through multiple cis-elements.

A fungal endoglucanase with plant cell wall extension activity

We have identified a wall hydrolytic enzyme from Trichoderma reesei with potent ability to induce extension of heat-inactivated type I cell walls. It is a small (23-kD) endo-1,4-beta-glucanase (Cel12A) belonging to glycoside hydrolase family 12. Extension of heat-inactivated walls from cucumber (Cucumis sativus cv Burpee Pickler) hypocotyls was induced by Cel12A after a distinct lag time and was accompanied by a large increase in wall plasticity and elasticity. Cel12A also increased the rate of stress relaxation of isolated walls at very short times (<200 ms; equivalent to reducing t(0), a parameter that estimates the minimum relaxation time). Similar changes in wall plasticity and elasticity were observed in wheat (Triticum aestivum cv Pennmore Winter) coleoptile (type II) walls, which showed only a negligible extension in response to Cel12A treatment. Thus, Cel12A modifies both type I and II walls, but substantial extension is found only in type I walls. Cel12A has strong endo-glucanase activity against xyloglucan and (1-->3,1-->4)-beta-glucan, but did not exhibit endo-xylanase, endo-mannase, or endo-galactanase activities. In terms of kinetics of action and effects on wall rheology, wall loosening by Cel12A differs qualitatively from the action by expansins, which induce wall extension by a non-hydrolytic polymer creep mechanism. The action by Cel12A mimics some of the changes in wall rheology found after auxin-induced growth. The strategy used here to identify Cel12A could be used to identify analogous plant enzymes that cause auxin-induced changes in cell wall rheology.

Islet-1 marks the early heart rudiments and is asymmetrically expressed during early rotation of the foregut in the chick embryo

Islet-1 (Isl-1), the LIM domain homeobox gene, is a well-known early marker of neuronal specification. Here, we show its spatial and temporal patterns of expression during early heart and gut development in the chick embryo. Isl-1 transcripts are first detected in the early cardiac progenitors and underlying endoderm at late stage 4. By stages 5-6, it is also expressed in the prechordal plate. From stage 6 onward, transcripts are also detected in the endoderm forming the anterior intestinal portal and floor of the caudal foregut. With progressive rostrocaudal fusion of the paired cardiac rudiments, Isl-1 expression is maintained in the cardiac mesoderm and associated endoderm. By the onset of heart beating, transcripts become restricted to the dorsal mesocardium and more caudal medial splanchnic mesoderm flanking the open gut. Within the foregut, Isl-1 is expressed in the endoderm of the oral membrane, thyroid rudiment, and second pharyngeal pouches, as well as within the second branchial grooves adjacent to the secondary pouches. Interestingly, with the onset of gut rotation, Isl-1 expression is detected unilaterally in the splanchnic mesodermal wall of the future greater curvature of the caudal stomach/rostral duodenum. Thus, Isl-1 is a novel and useful marker of the early cardiac rudiments and of the original left side of the rotating foregut. During early organogenesis, Isl-1 is also expressed in several other discrete domains as reported previously. Additionally, it is expressed at the interface between the hind limbs and trunk.

The prevalence and predictors of the use of alternative medicine in presurgical patients in five California hospitals

We measured the prevalence and predictors of the use of alternative medicine supplements in surgical patients by way of a self-administered questionnaire in consecutive patients > or = 18 yr old awaiting elective noncardiac surgery at five San Francisco Bay Area Hospitals. A total of 2560 patients completed the study survey (60% response rate). Of these patients, 39.2% admitted to using some form of alternative medicine supplements, of which herbal medicine was the most common type (67.6%). Of those who admitted to taking alternative medicine supplements, 44.4% did not consult with their primary physicians, and 56.4% did not inform the anesthesiologists before surgery regarding their use of these products; 53% of the patients ceased the use of these products before surgery. Multivariate logistic regression analysis revealed the following variables to be associated with the preoperative use of herbal medicine: female sex (odds radio [OR] 1.42, confidence interval [CI] 1.17-1.72), age 35-49 yr (OR 1.25, CI 1.02-1.53), higher income levels (OR 1.85, CI 1.50-2.27), Caucasian race (OR 1.34, CI 1.07-1.67), higher level of education (OR 1.35, CI 1.10-1.65), problems with sleep (OR 1.32, CI 1.05-1.66), problems with joints or back (OR 1.27, CI 1.04-1.56), allergies (OR 1.48, CI 1.21-1.82), problems with addiction (OR 1.90, CI 1.25-2.89), and a history of general surgery (OR 1.25, CI 1.03-1.52). In contrast, diabetes mellitus (OR 0.55, CI 0.36-0.86) and the use of antithrombotic medications (OR 0.57, CI 0.38-0.87) were associated with decreased odds of the use of herbal medicines. We concluded that the use of alternative medicine supplements by surgical patients is prevalent. Documentation of the use of these products is critical to determine the potential of drug or anesthetic interactions in the perioperative period.

IMPLICATIONS

The use of alternative medicine supplements by presurgical patients is prevalent. Documentation of the use of these products is critical to determine the potential of drug or anesthetic interactions in the perioperative period.

Neuronal pathways and transmission to the lower esophageal sphincter of the guinea Pig

BACKGROUND & AIMS

The lower esophageal sphincter (LES) normally controls the opening and closing of the gastroesophageal junction to resist gastric reflux but allow swallowing. Neuronal pathways controlling the guinea pig LES were investigated anatomically and physiologically in isolated preparations.

METHODS

Intracellular recording from the LES with focal electrical stimulation and retrograde and anterograde neuronal tracing were used.

RESULTS

Electrical stimulation on the LES evoked inhibitory junction potentials (IJPs), which were reduced by 60% by 100 micromol/L N-nitro-L-arginine and subsequently blocked by 0.5 micromol/L apamin, unmasking excitatory junction potentials, which were abolished by 1 micromol/L hyoscine. Esophageal or vagal stimulation evoked IJPs, which were blocked by 100 micromol/L hexamethonium. Focal stimulation of the upper stomach evoked IJPs at 5-8 of 20 stimulation sites, which were abolished by cutting between the stimulation site and sphincter. Application of 1,1'-didodecyl-3,3,3', 3'-tetramethyl indocarbocyanine perchlorate (DiI) to the gastric sling muscle anterogradely labeled many motor axons in the sling muscle but few in the LES, confirming that the two muscles are separately innervated. DiI on the esophagus labeled nerve fibers, but not cell bodies, in the upper stomach.

CONCLUSIONS

The inhibitory motor neurons of the LES receive inputs from the vagus nerve, esophagus, and upper stomach.

A gene therapy for cancer based on the angiogenesis inhibitor, vasostatin

The growth and persistence of solid tumors and their metastasis are angiogenesis-dependent. Vasostatin, the N-terminal domain of calreticulin inclusive of amino acids 1-180, is a potent angiogenesis inhibitor. To investigate whether intramuscular administration of vasostatin gene has the antitumor activity in mouse tumor models, we constructed a plasmid DNA encoding vasostatin and a control vector. Production and secretion of vasostatin protein by COS cells transfected with the plasmid DNA encoding vasostatin (pSecTag2B-vaso) were confirmed by Western blot analysis and ELISA. Conditioned medium from vasostatin-transfected COS cells apparently inhibited human umbilical vein endothelial cell (HUVEC) and mouse endothelial cell (SVEC4-10) proliferation, compared with conditioned medium from the COS cells transfected with control vector or non-transfected cells. Treatment with pSecTag2B-vaso twice weekly for 4 weeks resulted in the inhibition of tumor growth and the prolongation of the survival of tumor-bearing mice. The sustained high level of vasostatin protein in serum could be identified in ELISA. Angiogenesis was apparently inhibited in tumor by immunohistochemical analysis. Angiogenesis was also inhibited in the chicken embryo CAM assay and mouse corneal micropocket assay. The increased apoptotic cells were found within the tumor tissues from the mice treated with plasmid DNA encoding vasostatin. Taken together, the data in the present study indicate that the cancer gene therapy by the intramuscular delivery of plasmid DNA encoding vasostatin, is effective in the inhibition of the systemic angiogenesis and tumor growth in murine models. The present findings also provide further evidence of the anti-tumor effects of the vasostatin, and may be of importance for the further exploration of the application of this molecule in the treatment of cancer.

Retinoid signaling is required to complete the vertebrate cardiac left/right asymmetry pathway

Vitamin A-deficient (VAD) quail embryos have severe abnormalities, including a high incidence of reversed cardiac situs. Using this model we examined in vivo the physiological function of vitamin A in the left/right (L/R) cardiac asymmetry pathway. Molecular analysis reveals the expression of early asymmetry genes activin receptor IIa, sonic hedgehog, Caronte, Lefty-1, and Fgf8 to be unaffected by the lack of retinoids, while expression of the downstream genes nodal-related, snail-related (cSnR), and Pitx2 is altered. In VAD embryos nodal expression in left lateral plate mesoderm (LPM) is severely downregulated and the expression domain altered during neurulation. Similarly, the expression of cSnR in the right LPM and of Pitx2 in the left side posterior heart-forming region (HFR) is downregulated in the VAD embryos. The lack of retinoids does not cause randomization or ectopic expression of nodal, cSnR, or Pitx2. At the six- to eight-somite stage nodal is expressed transiently in the left posterior HFR of normal quail embryos; this expression is missing in VAD embryos and may be linked to the loss of Pitx2 expression in this region of VAD quail embryos. Administration of retinoids to VAD embryos prior to the six-somite stage rescues the expression of nodal, cSnR, and Pitx2 as well as the randomized VAD cardiac phenotype. There is an absolute requirement for retinoids at the four- to five-somite developmental window for cardiogenesis and cardiac L/R specification to proceed normally. We conclude that retinoids do not regulate the left/right-specific sidedness assignments for expression of genes on the vertebrate cardiac asymmetry pathway, but are required during neurulation for the maintenance of adequate levels of their expression and for the development of the posterior heart tube and a loopable heart. Cardiac asymmetry may be but one of several critical events regulated by retinoid signaling in the retinoid-sensitive developmental window.