bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular Bases of Viral RNA Targeting by Viral Small Interfering RNA-Programmed RISC
Authors: Pantaleo Vitantonio , Szittya György , Burgyán József
Published: February 2007

RNA silencing is conserved in a broad range of eukaryotes and operates in the development and maintenance of genome integrity in many organisms. Plants have adapted this system for antiviral defense, and plant viruses have in turn developed mechanisms to suppress RNA silencing. RNA silencing-related RNA inactivation is likely based on target RNA cleavage or translational arrest. Although it is widely assumed that virus-induced gene silencing (VIGS) promotes the endonucleolytic cleavage of the viral RNA genome, this popular assumption has never been tested experimentally. Here we analyzed the viral RNA targeting by VIGS in tombusvirus-infected plants, and we show evidence that antiviral response of VIGS is based on viral RNA cleavage by RNA-induced silencing effector complex (RISC) programmed by virus-specific small interfering RNAs (siRNAs). In addition, we found that the RISC-mediated cleavages do not occur randomly on the viral genome. Indeed, sequence analysis of cloned cleavage products identified hot spots for target RNA cleavage, and the regions of specific RISC-mediated cleavages are asymmetrically distributed along the positive- and negative-sense viral RNA strands. In addition, we identified viral siRNAs containing high-molecular-mass protein complexes purified from the recovery leaves of the silencing suppressor mutant virus-infected plants. Strikingly, these large nucleoproteins cofractionated with microRNA-containing complexes, suggesting that these nucleoproteins are silencing related effector complexes.
Evolutionary Insights into the Ecology of Coronaviruses
Authors: Vijaykrishna D. , Smith G. J. D. , Zhang J. X. , Peiris J. S. M. , Chen H. , Guan Y.
Published: February 2007

Although many novel members of the
Coronaviridae
have recently been recognized in different species, the ecology of coronaviruses has not been established. Our study indicates that bats harbor a much wider diversity of coronaviruses than any other animal species. Dating of different coronavirus lineages suggests that bat coronaviruses are older than those recognized in other animals and that the human severe acute respiratory syndrome (SARS) coronavirus was directly derived from viruses from wild animals in wet markets of southern China. Furthermore, the most closely related bat and SARS coronaviruses diverged in 1986, an estimated divergence time of 17 years prior to the outbreak, suggesting that there may have been transmission via an unknown intermediate host. Analysis of lineage-specific selection pressure also indicated that only SARS coronaviruses in civets and humans were under significant positive selection, also demonstrating a recent interspecies transmission. Analysis of population dynamics revealed that coronavirus populations in bats have constant population growth, while viruses from all other hosts show epidemic-like increases in population. These results indicate that diverse coronaviruses are endemic in different bat species, with repeated introductions to other animals and occasional establishment in other species. Our findings suggest that bats are likely the natural hosts for all presently known coronavirus lineages and that all coronaviruses recognized in other species were derived from viruses residing in bats. Further surveillance of bat and other animal populations is needed to fully describe the ecology and evolution of this virus family.
Changes in Gene Expression during Pegylated Interferon and Ribavirin Therapy of Chronic Hepatitis C Virus Distinguish Responders from Nonresponders to Antiviral Therapy
Authors: Taylor Milton W. , Tsukahara Takuma , Brodsky Leonid , Schaley Joel , Sanda Corneliu , Stephens Matthew J. , McClintick Jeanette N. , Edenberg Howard J. , Li Lang , Tavis John E. , Howell Charles , Belle Steven H.
Published: February 2007

Treating chronic hepatitis C virus (HCV) infection using pegylated alpha interferon and ribavirin leads to sustained clearance of virus and clinical improvement in approximately 50% of patients. Response rates are lower among patients with genotype 1 than with genotypes 2 and 3 and among African-American (AA) patients compared to Caucasian (CA) patients. Using DNA microarrays, gene expression was assessed for a group of 33 African-American and 36 Caucasian American patients with chronic HCV genotype 1 infection during the first 28 days of treatment. Results were examined with respect to treatment responses and to race. Patients showed a response to treatment at the gene expression level in RNA isolated from peripheral blood mononuclear cells irrespective of degree of decrease in HCV RNA levels. However, gene expression responses were relatively blunted in patients with poor viral response (<1.5 log10-IU/ml decrease at 28 days) compared to those in patients with a marked (>3.5 log10-IU/ml decrease) or intermediate (1.5 to 3.5 log10-IU/ml decrease) response. The number of genes that were up- or down-regulated by pegylated interferon and ribavirin treatment was fewer in patients with a poor response than in those with an intermediate or marked viral response. However AA patients had a stronger interferon response than CA patients in general. The induced levels of known interferon-stimulated genes such as the 2′5′-oligoadenylate synthetase, MX1, IRF-7, and toll-like receptor TLR-7 genes was lower in poor-response patients than in marked- or intermediate-response patients. Thus, the relative lack of viral response to interferon therapy of hepatitis C virus infection is associated with blunted interferon cell signaling. No specific regulatory gene could be identified as responsible for this global blunting or the racial differences.
Minor Capsid Proteins of Simian Virus 40 Are Dispensable for Nucleocapsid Assembly and Cell Entry but Are Required for Nuclear Entry of the Viral Genome
Authors: Nakanishi Akira , Itoh Noriko , Li Peggy P. , Handa Hiroshi , Liddington Robert C. , Kasamatsu Harumi
Published: February 2007

We investigated the roles of simian virus 40 capsid proteins in the viral life cycle by analyzing point mutants in Vp1 and Vp2/3, as well as a deletion mutant lacking the Vp2/3 coding sequence. The Vp1 mutants (V243E and L245E) and the Vp2/3 mutants (F157E-I158E and P164R-G165E-G166R) were previously shown to be defective in Vp1-Vp2/3 interaction and to be noninfectious or poorly infectious, respectively. Here, we show that all these point mutants form stable particles following DNA transfection into cells. The Vp2/3-mutant particles contained very low levels of Vp2/3, whereas the Vp1 mutant particles contained no detectable Vp2/3. As expected, the deletion mutant also formed particles that were noninfectious. We further characterized the two Vp1 point mutants and the deletion mutant. All three mutant particles comprised Vp1 and histone-associated viral DNA, and all were able to enter cells. However, the mutant complexes failed to associate with host importins (owing to the loss of the Vp2/3 nuclear localization signal), and the mutant viral DNAs prematurely dissociated from the Vp1s, suggesting that the nucleocapsids did not enter the nucleus. Consistently, all three mutant particles failed to express large T antigen. Together, our results demonstrate unequivocally that Vp2/3 is dispensable for the formation of nucleocapsids. Further, the nucleocapsids' ability to enter cells implies that Vp1 contains the major determinants for cell attachment and entry. We propose that the major role of Vp2/3 in infectivity is to mediate the nuclear entry of viral DNA.
Structure and Function of Flavivirus NS5 Methyltransferase
Authors: Zhou Yangsheng , Ray Debashish , Zhao Yiwei , Dong Hongping , Ren Suping , Li Zhong , Guo Yi , Bernard Kristen A. , Shi Pei-Yong , Li Hongmin
Published: February 2007

The plus-strand RNA genome of flavivirus contains a 5′ terminal cap 1 structure (m
7
GpppAmG). The flaviviruses encode one methyltransferase, located at the N-terminal portion of the NS5 protein, to catalyze both guanine N-7 and ribose 2′-OH methylations during viral cap formation. Representative flavivirus methyltransferases from dengue, yellow fever, and West Nile virus (WNV) sequentially generate GpppA → m
7
GpppA → m
7
GpppAm. The 2′-O methylation can be uncoupled from the N-7 methylation, since m
7
GpppA-RNA can be readily methylated to m
7
GpppAm-RNA. Despite exhibiting two distinct methylation activities, the crystal structure of WNV methyltransferase at 2.8 Å resolution showed a single binding site for
S
-adenosyl-
l
-methionine (SAM), the methyl donor. Therefore, substrate GpppA-RNA should be repositioned to accept the N-7 and 2′-O methyl groups from SAM during the sequential reactions. Electrostatic analysis of the WNV methyltransferase structure showed that, adjacent to the SAM-binding pocket, is a highly positively charged surface that could serve as an RNA binding site during cap methylations. Biochemical and mutagenesis analyses show that the N-7 and 2′-O cap methylations require distinct buffer conditions and different side chains within the K
61
-D
146
-K
182
-E
218
motif, suggesting that the two reactions use different mechanisms. In the context of complete virus, defects in both methylations are lethal to WNV; however, viruses defective solely in 2′-O methylation are attenuated and can protect mice from later wild-type WNV challenge. The results demonstrate that the N-7 methylation activity is essential for the WNV life cycle and, thus, methyltransferase represents a novel target for flavivirus therapy.
Radiology teaching material: website review
Authors: Shah M , Muquit S
Published: February 2007

Website review for appropriate knowledge on radiology for junior doctors
Hyperbaric oxygen (HBO2) treatment for a failing facial flap
Authors: McCrary Brian F
Published: February 2007

Hyperbaric oxygen (HBO2) is an approved treatment for 13 pathological entities. One of these indications—a failing facial flap—is presented in this case report of a traumatic wound to the face and right axilla after an unprovoked pit bull attack on a 4 year old girl. Surgical repair was started acutely but the facial flap became congested and ischaemic, indicating deterioration of the blood supply. HBO2 treatments were initiated twice a day, resulting in remarkably decreased swelling and discomfort after the first treatment. Leeching was also used to assist with reduction of venous congestion in the flap. The patient was discharged 5 days later with a well perfused, mostly intact, incision with minimal tenderness. Surgical repair was required for a small area of wound dehiscence. Photographs documenting the patient's progress with HBO2 are presented. A discussion of the mechanisms of action of HBO2 and its beneficial effects is provided in this case.
RADII AND BINDING ENERGIES OF NUCLEI IN THE ALPHA-CLUSTER MODEL
Authors: NIE G. K.
Published: February 2007

The α-cluster model is based on two assumptions that the proton–neutron pair interactions are responsible for adherence between α-clusters and that the NN-interaction in the α-clusters is isospin independent. It allows one to estimate the Coulomb energy and the short range inter-cluster bond energy in dependence on the number of clusters. The charge radii are calculated from the number of α-clusters too. Unlike the Weizsäcker formula in this model the binding energies of alpha-clusters and excess neutrons are estimated separately. The calculated values are in a good agreement with the experimental data.
Chronic psychological stress alters epithelial cell turn-over in rat ileum
Authors: Boudry Gaëlle , Jury Jennifer , Yang Ping Chang , Perdue Mary H.
Published: February 2007

Dysregulated epithelial cell kinetics associated with mucosal barrier dysfunction may be involved in certain intestinal disorders. We previously showed that chronic psychological stress, in the form of repetitive sessions of water avoidance stress (WAS), has a major detrimental impact on ileal barrier function. We hypothesized that these changes were related to a disturbance in enterocyte kinetics. Rats were submitted to WAS (1 h/day) for 5 or 10 days. As previously shown, permeability to macromolecules was enhanced in rats stressed for 5 and 10 days compared with controls. WAS induced a decrease in crypt depth at day 5 associated with an increased number of apoptotic cells. Cell proliferation was significantly increased at days 5 and 10. Villus height and the specific activity of sucrase were significantly reduced at day 10. We concluded that WAS induces a disturbance of epithelial cell kinetics, with the pattern depending on the duration of the stress period. These findings help to explain the mechanism underlying altered epithelial barrier function resulting from exposure to chronic psychological stress.
MIP-3α neutralizing monoclonal antibody protects against TNBS-induced colonic injury and inflammation in mice
Authors: Katchar Kianoosh , Kelly Ciarán P. , Keates Sarah , O'Brien Michael J. , Keates Andrew C.
Published: February 2007

A characteristic feature of human inflammatory bowel disease, particularly Crohn's disease, is the presence of activated CD4+T cells. Recently, we have shown that colonic epithelial cell production of macrophage inflammatory protein (MIP)-3α, a CD4 T cell-directed chemokine, is elevated in inflammatory bowel disease. However, the functional relevance of MIP-3α production during intestinal inflammation is poorly understood. The aim of this study was to determine whether MIP-3α production is increased during murine 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis and to examine the effect of anti-MIP-3α neutralizing monoclonal antibody administration in this model. We found that the administration of TNBS significantly increased colonic MIP-3α protein levels in Balb/c mice. Consistent with this, a marked increase in the number of CCR6-bearing lamina propria CD4+and CD8+T cells was also observed in TNBS-treated animals. Treatment of mice with an anti-MIP-3α neutralizing monoclonal antibody significantly reduced TNBS-mediated increases in colonic weight-to-length ratio, mucosal ulceration, histological damage, and myeloperoxidase activity. TNBS-mediated increases in the number of CCR6-bearing lamina propria T cells were also substantially reduced by anti-MIP-3α neutralizing monoclonal antibody treatment. Taken together, our findings indicate that blockade of MIP-3α bioactivity can significantly reduce TNBS-mediated colonic injury and T cell recruitment, suggesting a role for this chemokine in the pathophysiology of intestinal inflammation.
Aspirin before reperfusion blunts the infarct size limiting effect of atorvastatin
Authors: Birnbaum Yochai , Lin Yu , Ye Yumei , Martinez Juan D. , Huang Ming-He , Lui Charles Y. , Perez-Polo Jose R , Uretsky Barry F.
Published: February 2007

We assessed whether aspirin (acetylsalicylic acid, ASA), administered before reperfusion, abrogates the infarct size (IS)-limiting effect of atorvastatin (ATV). Statins reduce IS. This dose-dependent effect is mediated by upregulation of cycloxygenase-2 (COX2) and PGI2 production. Administration of selective COX2-inhibitors either with ATV for 3 days or immediately before coronary occlusion blocks the IS-limiting effect of ATV. Sprague-Dawley rats received 3-day ATV (10 mg·kg−1·day−1) or water alone. Rats underwent 30 min coronary artery occlusion and 4 h reperfusion (IS protocol, n = 8 in each group), or rats underwent 30 min coronary artery occlusion and 10 min reperfusion (enzyme expression and activity protocol, n = 4 in each group). Immediately before reperfusion rats received intravenous ASA (5, 10, or 20 mg/kg) or saline. Area-at-risk (AR) was assessed by blue dye and IS by triphenyltetrazolium chloride. ATV reduced IS (10.1 ± 1.4% of the AR) compared with controls (31.0 ± 2.2%). Intravenous ASA alone did not affect IS (29.0 ± 2.6%); however, ASA dose dependently (5, 10, and 20 mg/kg) attenuated the protective effect of ATV on IS (15.8 ± 0.9%, 22.0 ± 1.6%, and 23.7 ± 3.8%, respectively). ASA dose dependently blocked the upregulation of COX2 by ATV. COX2 activity was as follows: control, 8.93 ± 0.90 pg/mg; ATV, 75.85 ± 1.08 pg/mg; ATV + ASA5, 34.39 ± 1.48 pg/mg; ATV + ASA10, 19.87 ± 1.10 pg/mg; and ATV + ASA20, 9.36 ± 0.94 pg/mg. ASA, administered before reperfusion in doses comparable to those used in the clinical setting, abrogates the IS-limiting effect of ATV in a model with mechanical occlusion of the coronary artery. This potential adverse interaction should be further investigated in the clinical setting of acute coronary syndromes.
Conditioned preference for sweet stimuli in OLETF rat: effects of food deprivation
Authors: De Jonghe Bart C. , Hajnal Andras , Covasa Mihai
Published: February 2007

The Otsuka Long-Evans Tokushima Fatty (OLETF) rat, an outbred strain of Long- Evans Tokushima Otsuka rat (LETO) that lacks CCK-1 receptor expression, is hyperphagic and develops obesity and type-2 diabetes. The present study sought to assess how OLETF rats alter intake, preference, and conditioned preference of palatable solutions after acute food deprivation. Our results show that after 24 h chow restriction, LETO rats increase both sucrose intake and two-bottle sucrose preference relative to their free-fed baseline, whereas OLETF rats do not increase sucrose intake (0.3 M or 1.0 M sucrose) or preference (1.0 M vs. 0.3 M sucrose) when they are food deprived. In contrast, OLETF rats exhibit a higher conditioned flavor preference when sucrose is used as unconditioned stimulus (US) relative to LETO rats, whether overnight food restricted (81% vs. 71% for OLETF and LETO rats, respectively) or free fed (82% vs. 54% for OLETF and LETO rats, respectively) during the test. When a noncaloric saccharin solution is used as US, OLETF rats show a higher preference for the saccharin-associated flavor relative to LETO rats when nondeprived (76% vs. 58% for OLETF and LETO rats, respectively); however, neither strain shows differential conditioned flavor preference for saccharin in the deprivation state during the test. These findings suggest that OLETF rats fail to integrate postabsorptive and orosensory effects of sucrose in a conditioning setting to influence intake. Thus, it appears that OLETF rats form preferences for sucrose based largely on orosensory and hedonic properties of the solution, rather than caloric value.
Effects of dietary protein restriction on nephron number in the mouse
Authors: Hoppe Chantal C. , Evans Roger G. , Bertram John F. , Moritz Karen M.
Published: February 2007

In rats, maternal protein restriction reduces nephron endowment and often leads to adult hypertension. Sex differences in these responses have been identified. The molecular and genetic bases of these phenomena can best be identified in a mouse model, but effects of maternal protein restriction on kidney development have not been examined in mice. Therefore, we determined how combined prenatal and postnatal protein restriction in mice affects organ weight, glomerular number and dimensions, and renal expression of angiotensin receptor mRNA, in both male and female offspring. C57/BL6/129sv mice received either a normal (20% wt/wt; NP) or low (9% wt/wt; LP) protein diet during gestation and postnatal life. Offspring were examined at postnatal day 30. Protein restriction retarded growth of the kidney, liver, spleen, heart, and brain. All organs except the brain weighed less in female than male offspring. Protein restriction increased normalized (to body weight) brain weight, with females having relatively heavier brains than males. The effects of protein restriction were not sex dependent, except that normalized liver weight was reduced in males but increased in females. Glomerular volume, but not number, was greater in female than in male mice. Maternal protein restriction reduced nephron endowment similarly in male and female mice. Renal expression of AT1A receptor mRNA was approximately sixfold greater in female than male NP mice, but similar in male LP and female LP mice. We conclude that maternal protein restriction reduces nephron endowment in mice. This effect provides a basis for future studies of developmental programming in the mouse.
Exogenous T3mimics long day lengths in Siberian hamsters
Authors: Freeman David A. , Teubner Brett J. W. , Smith Carlesia D. , Prendergast Brian J.
Published: February 2007

Siberian hamsters ( Phodopus sungorus) exhibit seasonal cycles of reproduction driven by changes in day length. Day length is encoded endogenously by the duration of nocturnal melatonin (Mel) secretion from the pineal gland. Short-duration Mel signals stimulate reproduction and long-duration signals inhibit reproduction. The mechanism by which Mel signals are decoded at the level of neural target tissues remains uncharacterized. In Siberian hamsters, exposure to short day lengths or injections of Mel in long days results in a decrease in hypothalamic expression of type 2 iodothyronine deiodinase (Dio2) mRNA. Dio2 catalyzes the conversion of the thyroid hormone thyroxine to triiodothyronine (T3). Thus exposure to short and long day lengths should decrease and increase hypothalamic T3concentrations, respectively. We tested the hypothesis that exogenous T3administered to short-day hamsters would mimic exposure to long day lengths with respect to gonadal stimulation. Hamsters gestated and raised in short day lengths that exhibited photoinhibition of the testes were given daily subutaneous injections of T3or saline vehicle for 4 wk beginning at week 12 of life. The results indicate that exogenous T3induced gonadal growth in short-day hamsters and delayed spontaneous gonadal development by an interval equal to the number of weeks during which T3was administered. T3injections delayed gonadal regression if given coincident with the transfer of hamsters from long to short day lengths. These results suggest that T3mimics long day exposure in Siberian hamsters and may serve as an intermediate step between the Mel rhythm and the reproductive response.
Oxytocin knockout mice demonstrate enhanced intake of sweet and nonsweet carbohydrate solutions
Authors: Sclafani Anthony , Rinaman Linda , Vollmer Regis R. , Amico Janet A.
Published: February 2007

Oxytocin knockout (OT KO) mice display enhanced intake of nutritive and nonnutritive sweet solutions (i.e., sucrose and saccharin) compared with wild-type (WT) mice of the same C57BL/6 background strain. The present study further investigated the differential behavioral response of OT KO and WT mice to sucrose solutions and also examined intake preferences of OT KO and WT mice for palatable but nonsweet isocaloric solutions of carbohydrate and fat. A progressive ratio operant licking procedure demonstrated that OT KO and WT mice display a similar motivational drive to consume 10% sucrose. A series of two-bottle intake tests revealed that OT KO mice consume significantly larger amounts of both sweet and nonsweet carbohydrate solutions (i.e., sucrose, Polycose, and cornstarch) compared with WT cohorts. Intake pattern analyses revealed that OT KO mice overconsume carbohydrate solutions by initiating more drinking bouts compared with WT mice; bout sizes did not differ between the genotypes. In contrast, OT KO and WT mice did not differ in their intake of Intralipid, a palatable soybean oil emulsion. These findings indicate that the absence of OT in mice does not affect their appetitive drive to consume palatable sucrose solutions. Instead, the absence of OT may increase daily intake of palatable sweet and nonsweet solutions of carbohydrate (but not fat) by selectively blunting or masking processes that contribute to postingestive satiety.
Oral Administration of Tetrahydrobiopterin Slows the Progression of Atherosclerosis in Apolipoprotein E-Knockout Mice
Authors: Hattori Yoshiyuki , Hattori Sachiko , Wang Xi , Satoh Hiroko , Nakanishi Nobuo , Kasai Kikuo
Published: February 2007

Objective—

Although it has been reported that oral administration of tetrahydrobiopterin (BH4) prevents endothelial dysfunction and vascular oxidative stress in various rat models, the effect of treatment with BH4 on atherogenesis remains unclear.

Methods and Results—

In this study, we investigated whether oral BH4 treatment might slow the progression of atherosclerosis using hypercholesterolemic apolipoprotein E-knockout mice. We report that ingesting BH4 in drinking water is sufficient to inhibit atherogenesis in mice. Furthermore, we report that BH4 treatment improves endothelial dysfunction and attenuates increased mRNA expression of NADPH oxidase components, as well as a number of inflammatory factors, such as LOX-1 and MCP-1, in the aortas of apolipoprotein E- knockout mice.

Conclusion—

Strategies such as oral administration of BH4 to ensure continuous BH4 availability may be effective in restoring nitric oxide-mediated endothelial function and limiting vascular disease and the progression of atherosclerosis.
Plasma Fibrinogen, Ambulatory Blood Pressure, and Silent Cerebrovascular Lesions
Authors: Aono Yoko , Ohkubo Takayoshi , Kikuya Masahiro , Hara Azusa , Kondo Takeo , Obara Taku , Metoki Hirohito , Inoue Ryusuke , Asayama Kei , Shintani Yoriko , Hashimoto Junichiro , Totsune Kazuhito , Hoshi Haruhisa , Satoh Hiroshi , Izumi Shin-Ichi , Imai Yutaka
Published: February 2007

Objective—

Twenty-four–hour ambulatory blood pressure (24-hour ABP) values are considered a powerful predictor of stroke. Silent cerebrovascular lesions are associated with an increased risk of stroke. Because fibrinogen is a major determinant of plasma viscosity, an elevated fibrinogen level might also be associated with stroke risk. We evaluated the association of 24-hour ABP and plasma fibrinogen levels with the risk of silent cerebrovascular lesions (white matter hyperintensity and lacunar infarct) detected by MRI.

Methods and Results—

The study cohort comprised 958 individuals from the general population of Ohasama, a rural Japanese community. Multiple logistic regression analysis adjusted for age, sex, smoking and drinking status, use of antihypertensive medication, body mass index, 24-hour ABP, and a history of hypercholesterolemia, diabetes mellitus, and atrial fibrillation demonstrated that each 1-SD increase in fibrinogen level was associated with a significantly increased risk of silent cerebrovascular lesions (odds ratio, 1.26;
P
=0.001). The 24-hour ABP was also significantly and independently associated with the risk of silent cerebrovascular lesions. Even when 24-hour ABP values were within normal range (<135/80 mm Hg), elevated fibrinogen levels were associated with an increased risk of silent cerebrovascular lesions. Fibrinogen and 24-hour BP had additive effects on silent cerebrovascular lesions.

Conclusion—

The 24-hour ABP and plasma fibrinogen levels were closely and independently associated with the risk of silent cerebrovascular lesions including white matter hyperintensity and lacunar infarct.
Downregulation of Bone Morphogenetic Protein 4 Expression in Coronary Arterial Endothelial Cells
Authors: Csiszar Anna , Labinskyy Nazar , Smith Kira E. , Rivera Aracelie , Bakker Erik N.T.P. , Jo Hanjoong , Gardner Jason , Orosz Zsuzsanna , Ungvari Zoltan
Published: February 2007

Objective—Bone morphogenetic protein 4 (BMP-4) is a transforming growth factor β family member cytokine that exerts proinflammatory effects on the endothelium and is likely to play a role in atherogenesis. Recent studies suggested that atheroprotective levels of shear stress control endothelial BMP-4 expression; however, the underlying mechanisms remained unknown.

Methods and Results—We found that shear stress downregulated BMP-4 expression in human and rat coronary arterial endothelial cells (CAECs) as well as in cultured mesenteric arterioles, although it had no effect on the expression of BMP-2, a related cytokine. In human coronary arterial endothelial cells, 8-bromo-cAMP, the adenylate cyclase activator forskolin, or a cAMP-dependent protein kinase (PKA) activator effectively decreased BMP-4 expression, mimicking the effects of shear stress. Indeed, shear stress induced the nuclear translocation of PKA-c, and inhibition of PKA attenuated the effects of shear stress and forskolin on BMP-4 expression. RNA decay assay and BMP-4 promoter-driven luciferase reporter gene assay showed that cAMP regulates BMP-4 expression at the transcriptional level.

Conclusions—Laminar shear stress and the cAMP/PKA pathway are important negative regulators of BMP-4 expression in the vascular endothelium. Because BMP-4 elicits endothelial activation and dysfunction, hypertension, and vascular calcification, inhibition of BMP-4 expression by shear stress and the cAMP/PKA pathway is likely to exert antiatherogenic and vasculoprotective effects.
Anti–LOX-1 Rescues Endothelial Function in Coronary Arterioles in Atherosclerotic ApoE Knockout Mice
Authors: Xu Xiangbin , Gao Xue , Potter Barry J. , Cao Ji-Min , Zhang Cuihua
Published: February 2007

Background—

We hypothesized that atherosclerosis inhibits NO-mediated endothelium-dependent dilation of coronary arterioles through interaction of ox-LDL with its receptor, LOX-1, through the production of O
2
ÿ
−
in endothelial cells.

Methods and Results—

We assessed the role of ox-LDL in endothelial dysfunction in a murine model of atherosclerosis (ApoE KO mice). Coronary arterioles from WT control and ApoE KO mice were isolated and pressurized without flow. Although dilation of vessels to endothelium-independent vasodilator SNP was not altered between ApoE KO and WT mice, dilation to the endothelium-dependent agonist, ACh was reduced in ApoE KO versus WT mice. Impaired vasodilation to ACh in ApoE KO mice is partially restored by NAD(P)H oxidase inhibitor, apocynin or DPI. Messenger RNA expression for NAD(P)H oxidases was higher in ApoE KO mice than that in WT and anti–LOX-1 treated ApoE KO mice. Anti–LOX-1, given in vivo, restored NO-mediated coronary arteriolar dilation in ApoE KO mice, but did not affect the endothelium-dependent vasodilation in controls.

Conclusions—

These results suggest that ox-LDL impairs endothelium-dependent NO-mediated dilation of coronary arterioles by activation of a signaling cascade involving LOX-1 and NAD(P)H oxidase expression.
Plasmin Induces Endothelium-Dependent Nitric Oxide–Mediated Relaxation in the Porcine Coronary Artery
Authors: Fujiyoshi Tetsuhiro , Hirano Katsuya , Hirano Mayumi , Nishimura Junji , Takahashi Shosuke , Kanaide Hideo
Published: February 2007

Objective—Plasmin is a key enzyme in fibrinolysis. We attempted to determine the possible role of plasmin in the regulation of vascular tone, while also investigating the mechanism of plasmin-induced vasorelaxation.

Methods and Results—In porcine coronary artery, plasmin induced an endothelium-dependent relaxation. This relaxing effect was mostly abolished by a proteinase inhibitor, a plasmin inhibitor, or a nitric oxide (NO) synthase inhibitor. The preceding stimulation with plasmin significantly inhibited the subsequent relaxation induced by thrombin but not that induced by proteinase-activated receptor-1–activating peptide. The relaxation induced by trypsin and substance P remained unaffected by the preceding plasmin stimulation. The pretreatment with plasmin, thrombin, or trypsin significantly attenuated the plasmin-induced relaxation. In porcine coronary artery endothelial cells (PCAECs) and human umbilical vein endothelial cells (HUVECs), plasmin induced a transient elevation in the cytosolic Ca2+concentrations ([Ca2+]i). The preceding stimulation with plasmin inhibited the subsequent [Ca2+]ielevation induced by thrombin but not that induced by trypsin. In PCAECs, plasmin concentration-dependently induced NO production.

Conclusions—The present study demonstrated, for the first time, that plasmin induced an endothelium-dependent NO-mediated relaxation in the porcine coronary artery, while also showing plasmin to specifically inactivate the thrombin receptor.
Phenotypic Heterogeneity of the Endothelium
Authors: Aird William C.
Published: February 2007

Endothelial cells, which form the inner cellular lining of blood vessels and lymphatics, display remarkable heterogeneity in structure and function. This is the first of a 2-part review focused on phenotypic heterogeneity of blood vessel endothelium. This review provides an historical perspective of our understanding of endothelial heterogeneity, discusses the scope of phenotypic diversity across the vascular tree, and addresses proximate and evolutionary mechanisms of endothelial cell heterogeneity. The overall goal is to underscore the importance of phenotypic heterogeneity as a core property of the endothelium.
Muscle Ring Finger 1, but not Muscle Ring Finger 2, Regulates Cardiac Hypertrophy In Vivo
Authors: Willis Monte S. , Ike Christopher , Li Luge , Wang Da-Zhi , Glass David J. , Patterson Cam
Published: February 2007

Muscle ring finger (MuRF) proteins have been implicated in transmitting mechanical forces to cell signaling pathways through their interactions with the giant protein titin. Recent evidence has linked mechanically-induced stimuli with the control of serum response factor activity and localization through MuRF2. This observation is particularly intriguing in the context of cardiac hypertrophy, where serum response factor transactivation is a key event necessary for the induction of cardiac hypertrophy in response to increased afterload. We have previously reported that MuRF1, which is also a titin-associated protein, exerts antihypertrophic activity in vitro. In the present study, we induced cardiac hypertrophy in mice lacking MuRF1 and MuRF2 to distinguish the physiologic role of these divergent proteins in vivo. We identified for the first time that MuRF1, but not MuRF2, plays a key role in regulating the induction of cardiac hypertrophy, likely by its direct interactions with serum response factor. These studies describe for the first time distinct and nonoverlapping functional characteristics of MuRF1 and MuRF2 in response to cardiac stress in vivo.
Predictors of Carotid Intima-Media Thickness Progression in Young Adults
Authors: Johnson Heather M. , Douglas Pamela S. , Srinivasan Sathanur R. , Bond M. Gene , Tang Rong , Li Shengxu , Chen Wei , Berenson Gerald S. , Stein James H.
Published: February 2007

Background and Purpose—

We sought to evaluate the predictors of carotid intima-media thickness (CIMT) progression in young adults and to determine whether they differed between the sexes. Although risk factors for the progression of atherosclerosis in middle-aged and elderly adults are well known, they are less well understood in young adults. CIMT is a validated measure of subclinical atherosclerosis.

Methods—

B-mode ultrasound images of the far walls of both carotid arteries were obtained in 336 young adults in the Bogalusa Heart Study, whose mean±SD age was 32.3±3.0 years. CIMT and risk factors were measured at baseline (1995–1996) and after 5.8±0.6 years. Multivariable regression was used to determine the predictors of CIMT progression.

Results—

CIMT progression rates in women (0.015±0.024 mm/y) and men (0.020±0.027 mm/y) were not statistically different after controlling for body mass index (
P
=0.155). Smoking was a statistically significant predictor of common and composite CIMT progression in both sexes. In men, systolic blood pressure was an independent predictor of internal carotid and composite CIMT progression, fasting glucose predicted common CIMT progression, and family history predicted composite CIMT progression.

Conclusions—

In young adults, smoking was a consistent predictor of short-term CIMT progression in men and women. Traditional risk factors also predicted CIMT progression in men.
Influence of Hyperglycemia on Oxidative Stress and Matrix Metalloproteinase-9 Activation After Focal Cerebral Ischemia/Reperfusion in Rats
Authors: Kamada Hiroshi , Yu Fengshan , Nito Chikako , Chan Pak H.
Published: February 2007

Background and Purpose—

Hyperglycemia is linked to a worse outcome after ischemic stroke. Among the manifestations of brain damage caused by ischemia are blood-brain barrier (BBB) disruption and edema formation. Oxidative stress and matrix metalloproteinase-9 (MMP-9) activation are implicated in BBB dysfunction after ischemia/reperfusion injury. Our present study was designed to clarify the relation among hyperglycemia, oxidative stress, and MMP-9 activation associated with BBB dysfunction after transient focal cerebral ischemia (tFCI).

Methods—

We used a model of 60 minutes of middle cerebral artery occlusion on the following animals: normoglycemic wild-type rats, wild-type rats with hyperglycemia induced by streptozotocin, and human copper/zinc superoxide dismutase (SOD1) transgenic rats with streptozotocin-induced hyperglycemia. We evaluated edema volume, Evans blue leakage, and oxidative stress, such as the carbonyl groups and oxidized hydroethidine (HEt), SOD activity, and gelatinolytic activity, including MMP-9.

Results—

Hyperglycemia significantly increased edema volume and Evans blue leakage. Moreover, it enhanced the levels of the carbonyl groups, the oxidized HEt signals, and MMP-9 activity after tFCI without alteration in SOD activity. Gelatinolytic activity and oxidized HEt signals had a clear spatial relation in the hyperglycemic rats. SOD1 overexpression reduced the hyperglycemia-enhanced Evans blue leakage and MMP-9 activation after tFCI.

Conclusions—

Hyperglycemia increases oxidative stress and MMP-9 activity, exacerbating BBB dysfunction after ischemia/reperfusion injury. Superoxide overproduction may be a causal link among hyperglycemia, MMP-9 activation, and BBB dysfunction.
Hypoxic Preconditioning Induces Neuroprotective Stanniocalcin-1 in Brain via IL-6 Signaling
Authors: Westberg Johan A. , Serlachius Martina , Lankila Petri , Penkowa Milena , Hidalgo Juan , Andersson Leif C.
Published: February 2007

Background and Purpose—

Exposure of animals for a few hours to moderate hypoxia confers relative protection against subsequent ischemic brain damage. This phenomenon, known as hypoxic preconditioning, depends on new RNA and protein synthesis, but its molecular mechanisms are poorly understood. Increased expression of IL-6 is evident, particularly in the lungs of animals subjected to hypoxic preconditioning. Stanniocalcin-1 (STC-1) is a 56-kDa homodimeric glycoprotein originally discovered in bony fish, where it regulates calcium/phosphate homeostasis and protects against toxic hypercalcemia. We originally reported expression of mammalian STC-1 in brain neurons and showed that STC-1 guards neurons against hypercalcemic and hypoxic damage.

Methods—

We treated neural Paju cells with IL-6 and measured the induction of
STC-1
mRNA. In addition, we quantified the effect of hypoxic preconditioning on
Stc-1
mRNA levels in brains of wild-type and IL-6 deficient mice. Furthermore, we monitored the
Stc-1
response in brains of wild-type and transgenic mice, overexpressing IL-6 in the astroglia, before and after induced brain injury.

Results—

Hypoxic preconditioning induced an upregulated expression of
Stc-1
in brains of wild-type but not of IL-6–deficient mice. Induced brain injury elicited a stronger STC-1 response in brains of transgenic mice, with targeted astroglial IL-6 expression, than in brains of wild-type mice. Moreover, IL-6 induced
STC-1
expression via MAPK signaling in neural Paju cells.

Conclusion—

These findings indicate that IL-6–mediated expression of STC-1 is one molecular mechanism of hypoxic preconditioning-induced tolerance to brain ischemia.
Low-Grade Inflammation Is a Risk Factor for Clinical Stroke Events in Addition to Silent Cerebral Infarcts in Japanese Older Hypertensives
Authors: Ishikawa Joji , Tamura Yurie , Hoshide Satoshi , Eguchi Kazuo , Ishikawa Shizukiyo , Shimada Kazuyuki , Kario Kazuomi
Published: February 2007

Background and Purpose—

High-sensitivity C-reactive protein (hsCRP), a marker of inflammation, is associated with atherosclerosis, hypertensive target organ damage, and cardiovascular events. In the general Japanese population, the level of hsCRP is reported to be lower than that in Western countries, and the relationships among hsCRP, silent cerebral infarcts (SCIs), and clinical stroke events in older Japanese hypertensives remain unclear.

Methods—

We conducted brain MRI and measured hsCRP at baseline in 514 older Japanese hypertensives (clinic blood pressure ≥140/90 mm Hg, age ≥50 years old) who were enrolled in the Jichi Medical School ABPM Study, wave 1. They were followed up for an average of 41 months (range: 1 to 68 months, 1751 person-years) and the incidence of subsequent clinical stroke events was evaluated.

Results—

The subjects with SCIs at baseline (n=257) had a higher hsCRP level than those without SCIs (geometric mean hsCRP [SD range]; 0.19 [0.18 to 0.21] versus 0.14 [0.13 to 0.16] mg/L,
P
=0.007) after adjustment for confounding factors, and the OR for the presence of SCIs was increased with the quartile of hsCRP levels. In Cox regression analysis, the patients with above median hsCRP level (≥0.21 mg/L) (hazard ratio [HR]: 2.50, 95% CI: 1.24 to 5.00,
P
=0.01) and those with SCIs (HR: 4.60, 95% CI: 1.91 to 11.03,
P
=0.001) at baseline had independently higher risks for clinical stroke events after adjustment for age, smoking status, antihypertensive medication use, and 24-hour systolic blood pressure level. Compared with the patients with below median hsCRP level without SCIs, those with above median hsCRP level and SCIs at baseline had a higher risk for clinical stroke events (HR: 7.32, 95% CI: 2.17 to 24.76,
P
=0.001), although those with below median hsCRP level and SCIs (HR: 2.46, 95% CI: 0.64 to 9.47,
P
=0.19) and those with above median hsCRP level without SCIs (HR: 1.11, 95% CI: 0.22 to 5.55,
P
=0.90) did not have significant risks.

Conclusion—

High-sensitivity C-reactive protein is a risk factor for clinical stroke events in addition to silent cerebral infarcts in Japanese older hypertensives, indicating that the risk for clinical stroke events increases with preexisting hypertensive target organ damage in the brain and additionally with ongoing low-grade inflammation.
Outcomes Validity and Reliability of the Modified Rankin Scale: Implications for Stroke Clinical Trials
Authors: Banks Jamie L. , Marotta Charles A.
Published: February 2007

Background and Purpose—

The modified Rankin scale (mRS), a clinician-reported measure of global disability, is widely applied for evaluating stroke patient outcomes and as an end point in randomized clinical trials. Extensive evidence on the validity of the mRS exists across a large but fragmented literature. As new treatments for acute ischemic stroke are submitted for agency approval, an appreciation of the mRS’s attributes, specifically its relationship to other stroke evaluation scales, would be valuable for decision-makers to properly assess the impact of a new drug on treatment paradigms. The purpose of this report is to assemble and systematically assess the properties of the mRS to provide decision-makers with pertinent evaluative information.

Methods—

A Medline search was conducted to identify reports in the peer-reviewed medical literature (1957–2006) that provide information on the structure, validation, scoring, and psychometric properties of the mRS and its use in clinical trials. The selection of articles was based on defined criteria that included relevance, study design and use of appropriate statistical methods.

Results—

Of 224 articles identified by the literature search, 50 were selected for detailed assessment. Inter-rater reliability with the mRS is moderate and improves with structured interviews (κ 0.56 versus 0.78); strong test-re-test reliability (κ=0.81 to 0.95) has been reported. Numerous studies demonstrate the construct validity of the mRS by its relationships to physiological indicators such as stroke type, lesion size, perfusion and neurological impairment. Convergent validity between the mRS and other disability scales is well documented. Patient comorbidities and socioeconomic factors should be considered in properly applying and interpreting the mRS. Recent analyses suggest that randomized clinical trials of acute stroke treatments may require a smaller sample size if the mRS is used as a primary end point rather than the Barthel Index.

Conclusions—

Multiple types of evidence attest to the validity and reliability of the mRS. The reported data support the view that the mRS is a valuable instrument for assessing the impact of new stroke treatments.
How Purely Wind-Driven Long Planetary Geostrophic Waves May Be Energized in the Western Part of Ocean Subtropical Gyres
Authors: Cerovečki Ivana , de Szoeke Roland
Published: February 2007

Satellite observations and idealized numerical studies reveal intensification of long-period (on the order of one cycle per year) waves in the western part of ocean basins. The authors explore the idea that the intensification is associated with the spatial growth of purely time periodic, but baroclinically unstable, motions. The framework is a simple idealized 2½-layer model in which only the upper layer is directly forced by the wind, a setting similar to the shadow zone of the Luyten–Pedlosky–Stommel (LPS) model. The upper two layers participate in the wave motion, which is driven by a large-scale wind stress fluctuating with the annual period, representing the seasonal cycle. Although possibly unstable solutions exist everywhere in the subtropical gyre on account of the nonzero meridional background flow, they are not seen in the eastern part of the basin in satellite observations nor are they excited there by model gyre-scale annual-period winds. Instead, energy injected into the model ocean at a fixed frequency and with zonal and meridional wavenumbers, such that the resulting flow perturbation is locally stable, refracts westward as it propagates through the spatially varying background flow without change of frequency and reaches distant regions where the spatial wavenumber becomes complex so that spatial growth occurs. This process results in spatially growing solutions of annual or near-annual frequency only in the southwestern part of the model subtropical gyre, thus explaining why the intensification is preferentially manifested in the southwestern subtropical gyre in published numerical model results. The paper concludes with a discussion of relevant satellite and in situ observations.
A Consistent Theory for Linear Waves of the Shallow-Water Equations on a Rotating Plane in Midlatitudes
Authors: Paldor Nathan , Rubin Shira , Mariano Arthur J.
Published: February 2007

The present study provides a consistent and unified theory for the three types of linear waves of the shallow-water equations (SWE) in a zonal channel on the β plane: Kelvin, inertia–gravity (Poincaré), and planetary (Rossby). The new theory is formulated from the linearized SWE as an eigenvalue problem that is a variant of the classical Schrödinger equation. The results of the new theory show that Kelvin waves exist on the β plane with vanishing meridional velocity, as is the case on the f plane, without any change in the dispersion relation, while the meridional structure of their height amplitude is trivially modified from exponential on the f plane to a one-sided Gaussian on the β plane. Similarly, inertia–gravity waves are only slightly modified in the new theory in comparison with their characteristics on the f plane. For planetary waves (which exist only on the β plane) the new theory yields a similar dispersion relation to the classical theory only for large gravity wave phase speed, such as those encountered in a barotropic ocean or an equivalent barotropic atmosphere. In contrast, for low gravity wave phase speed, for example, those in an equivalent barotropic ocean where the relative density jump at the interface is 10−3, the phase speed of planetary waves in the new theory is 2 times those of the classical theory. The ratio between the phase speeds in the two theories increases with channel width. This faster phase propagation is consistent with recent observation of the westward propagation of crests and troughs of sea surface height made by the altimeter aboard the Ocean Topography Experiment (TOPEX)/Poseidon satellite. The new theory also admits inertial waves, that is, waves that oscillate at the local inertial frequency, as a genuine solution of the eigenvalue problem.