bluuebunny/crossref_metadata_2025 huggingface dataset:
The “Benzothiazine” Chromophore of Pheomelanins: A Reassessment†
Authors: Napolitano Alessandra , De Lucia Maria , Panzella Lucia , D’Ischia Marco
Published: November 2007

The characteristic absorption and photochemical properties of pheomelanins are generally attributed to “benzothiazine” structural units derived biogenetically from 5‐S‐cysteinyldopa. This notion, however, conveys little or no information about the structural chromophores responsible for the photoreactivity of pheomelanins. At pH 7.4, natural and synthetic pheomelanins show a defined maximum around 305 nm, which is not affected by reductive treatment with sodium borohydride, and a monotonic decrease in the absorption in the range 350–550 nm. These features are not compatible with a significant proportion of structural units related to 2H‐1,4‐benzothiazine and 2H‐1,4‐benzothiazine‐3‐carboxylic acid, the early borohydride‐reducible pheomelanin precursors featuring absorption maxima above 340 nm. Rather, these features would better accommodate a contribution by the nonreducible 3‐oxo‐3,4‐dihydrobenzothiazine (λmax 299 nm) and benzothiazole (λmax 303 nm) structural motifs, which are generated in the later stages of pheomelanogenesis in vitro. This conclusion is supported by a detailed liquid chromatography/UV and mass spectrometry monitoring of the species formed in the oxidative conversion of 5‐S‐cysteinyldopa to pheomelanin, and would point to a critical reassessment of the commonly reported “benzothiazine” chromophore in terms of more specific and substantiated structural units, like those formed during the later stages of pheomelanin synthesis in vitro.
Agreement Between Diary Records of Time Spent Outdoors and Personal Ultraviolet Radiation Dose Measurements
Authors: Chodick Gabriel , Kleinerman Ruth A. , Linet Martha S. , Fears Tom , Kwok Richard K. , Kimlin Michael G. , Alexander Bruce H. , Freedman Daryl M.
Published: November 2007

Little is known about the validity of self‐recorded sun exposure and time spent outdoors for epidemiological research. The aims of the current study were to assess how well participants’ self‐recorded time outdoors compared to objective measurements of personal UVR doses. We enrolled 124 volunteers aged 40 and above who were identified from targeted subgroups of US radiologic technologists. Each volunteer was instructed to wear a polysulfone (PS) dosimeter to measure UVR on their left shoulder and to complete a daily activity diary, listing all activities undertaken in each 30 min interval between 9:00 A.M. and 5:00 P.M. during a 7 day period. In a linear regression model, self‐recorded daily time spent outdoors was associated with an increase of 8.2% (95% CI: 7.3–9.2%) in the personal UVR exposure with every hour spent outdoors. The amount of self‐recorded total daily time spent outdoors was better correlated with the personal daily UVR dose for activities conducted near noon time compared to activities conducted in the morning or late afternoon, and for activities often performed in the sun (e.g. gardening or recreation activities) compared to other outdoor activities (e.g. driving) in which the participant is usually shaded from the sun. Our results demonstrated a significant correlation between diary records of time spent outdoors with objective personal UVR dose measurements.
Isotopic and Elemental Imaging of Geological Materials by Laser Ablation Inductively Coupled Plasma‐Mass Spectrometry
Authors: Woodhead Jon D. , Hellstrom John , Hergt Janet M. , Greig Alan , Maas Roland
Published: November 2007

Laser ablation ICP‐MS represents a promising new development for the acquisition of elemental and isotopic images from a variety of different materials. Compared to existing methods for imaging, it offers relatively rapid throughput, very wide dynamic range, a relatively clean mass spectrum, utility at a variety of scales (from μm to cm) and multi‐element/isotopic capability. Although developing rapidly in the biological sciences, the method has not yet seen widespread application to geological materials. This contribution documents some preliminary experiments aimed at understanding the fundamental aspects of elemental and isotopic image acquisition using laser ablation ICP‐MS. In particular, we note that ablation cell designs must be optimised to promote rapid system response, in contrast to the signal‐smoothing that is often preferred for simple spot analyses. Furthermore, experimental parameters must be carefully evaluated on a system‐by‐system basis to avoid the blurring effects of re‐sampling phenomena. With careful attention to these details, and development of appropriate data processing software, laser ablation ICP‐MS imaging has much to offer workers in the Earth and environmental sciences.
Both Notch1 and Notch2 contribute to the regulation of melanocyte homeostasis
Authors: Kumano Keiki , Masuda Shigeo , Sata Masataka , Saito Toshiki , Lee Suk‐young , Sakata‐Yanagimoto Mamiko , Tomita Taisuke , Iwatsubo Takeshi , Natsugari Hideaki , Kurokawa Mineo , Ogawa Seishi , Chiba Shigeru
Published: November 2007

Notch signaling affects a variety of mammalian stem cells, but there has been limited evidence that a specific Notch molecule regulates adult stem cells. Recently, it was reported that the reduced Notch signaling initiated at the embryonic stage results in a gradual hair graying phenotype after birth. Here we demonstrate that the oral administration of a γ‐secretase inhibitor (GSI) to wild‐type adult C57/Bl6 mice led to a gradual increase in gray spots, which remained unchanged for at least 20 weeks after discontinuing the GSI. In GSI‐treated mice, there was a severe decrease in unpigmented melanocytes in the bulge/subbulge region where melanocyte stem cells are located. While we confirmed that Notch1+/−Notch2+/− double heterozygous mice with a C57/Bl6 background were born with a normal hair color phenotype and gradually turned gray after the second hair cycle, in the c‐kit mutant Wv background, Notch1+/− and Notch2+/− mice had larger white spots on the first appearance of hair than did the Wv/+ mice, which did not change throughout life. Notch1+/−Notch2+/−Wv/+ mice had white hair virtually all over the body at the first appearance of hair and the depigmentation continued to progress thereafter. Using a neural crest organ culture system, GSI blocked the generation of pigmented melanocytes when added to the culture during the period of melanoblast proliferation, but not during the period of differentiation. These observations imply roles of Notch signaling in both development of melanocyte during embryogenesis and maintenance of melanocyte stem cells in adulthood, while the degree of requirement is distinct in these settings: the latter is more sensitive than the former to the reduced Notch signaling. Furthermore, Notch1 and Notch2 cooperates with c‐kit signaling during embryogenesis, and they cooperate with each other to regulate melanocyte homeostasis after birth.
Regulation of innate immunity against hepatitis C virus infection
Authors: Saito Takeshi , Gale Michael
Published: November 2007

Chronic hepatitis C virus (HCV) infection is a global public health problem. HCV infection is treated with type I interferon (IFN), a natural product that is produced by cells during virus infection as a result of innate immune signaling events. The secreted IFN alert the surrounding cells to turn on an “antiviral state” that resists infection. In general, the role of innate immune response is to suppress viral replication and to induce cytokines and other factors that promote adaptive immunity and the resolution of infection. The mechanisms by which the innate immune response and IFN actions limit HCV infection are not well defined, but are likely to involve the function of specific IFN‐stimulated genes. HCV also copesintensively with immune responses in order to establish persistent infection. Recent studies reveal that a other viruses use similar tactics to regulate the antiviral innate immune response. In the case of HCV, innate immune signaling is strictly controlled by the viral NS3/4A protease, resulting in the disruption of IFN production. Here, we summarize the current understanding of how HCV evades the innate immune system.
Detection of Murine Norovirus 1 by Using Plaque Assay, Transfection Assay, and Real-Time Reverse Transcription-PCR before and after Heat Exposure
Authors: Baert Leen , Wobus Christiane E. , Van Coillie Els , Thackray Larissa B. , Debevere Johan , Uyttendaele Mieke
Published: November 2007

The correlation between the detection of murine norovirus 1 RNA by real-time reverse transcription-PCR and the infectivity by plaque assay before and after heat exposure (80°C) was examined. No correlation was found in the current study. Moreover, heat inactivation had a much stronger detrimental effect on virus infectivity than on the integrity of the viral genome.
Plasmid Patterns of
Bacillus thuringiensis
Type Strains
Authors: Reyes-Ramírez Arturo , Ibarra Jorge E.
Published: November 2007

Practically all
Bacillus thuringiensis
strains contain a set of self-replicating, extrachromosomal DNA molecules or plasmids, which vary in number and size in the different strains. The plasmid patterns obtained from gel electrophoresis have previously been used as a tool to characterize strains, but comparison of the plasmid patterns has been limited in the number and diversity of strains analyzed. In this report, we were able to compare the plasmid patterns of 83 type strains (out of 84) and 47 additional strains from six serotypes. The information obtained from this comparison showed the importance of this tool as a strain characterization procedure and indicates the complexity and uniqueness of this feature. For example, with one exception, all type strains showed a unique plasmid pattern. All were unique in such a way that none showed even a single comigrating plasmid in the agarose gels, and therefore, cluster analysis was impossible, indicating that plasmid patterns are qualitative rather than quantitative features. Furthermore, comparison between strains belonging to the same serotype showed a great difference in variability. Some serotypes (e.g., israelensis) showed the same basic pattern among all its strains, while other serotypes (e.g., morrisoni) showed a great diversity of patterns. These results indicate that plasmid patterns are valuable tools to discriminate strains below the serotype level.
An Engineered Chymotrypsin/Cathepsin G Site in Domain I Renders
Bacillus thuringiensis
Cry3A Active against Western Corn Rootworm Larvae
Authors: Walters Frederick S. , Stacy Cheryl M. , Lee Mi Kyong , Palekar Narendra , Chen Jeng S.
Published: November 2007

The western corn rootworm remains one of the most important pests of corn in the United States despite the use of many pest management tools. Cry3A, the first coleopteran-active
Bacillus thuringiensis
toxin isolated, has not been useful for control of the corn rootworm pest complex. Modification of Cry3A so that it contained a chymotrypsin/cathepsin G protease recognition site in the loop between α-helix 3 and α-helix 4 of domain I, however, resulted in consistent activity of the toxin (“mCry3A”) against neonate western corn rootworm. In vitro chymotrypsin digests showed that there was a substantial difference between the enzyme sensitivity of mCry3A and the enzyme sensitivity of Cry3A, with mCry3A rapidly converted from a 67-kDa form to a ∼55-kDa form. The introduced protease site was also recognized in vivo, where the ∼55-kDa form of mCry3A toxin was rapidly generated and associated with the membrane fraction. After a point mutation in m
cry3A
that resulted in the elimination of the native domain I chymotrypsin site (C terminal to the introduced chymotrypsin/cathepsin G protease site of mCry3A), the in vitro and in vivo digestion patterns remained the same, demonstrating that the introduced site was required for the enhanced activity. Also, 55-kDa mCry3A generated by cleavage with chymotrypsin exhibited specific binding to western corn rootworm brush border membrane, whereas untreated 67-kDa mCry3A did not. These data indicate that the mCry3A toxicity for corn rootworm larvae was due to the introduction of a chymotrypsin/cathepsin G site, which enhanced cleavage and subsequent binding of the activated toxin to midgut cells.
CodY ofStreptococcus pneumoniae: Link between Nutritional Gene Regulation and Colonization
Authors: Hendriksen Wouter T. , Bootsma Hester J. , Estevão Silvia , Hoogenboezem Theo , de Jong Anne , de Groot Ronald , Kuipers Oscar P. , Hermans Peter W. M.
Published: November 2007

CodY is a nutritional regulator mainly involved in amino acid metabolism. It has been extensively studied inBacillus subtilisandLactococcus lactis. We investigated the role of CodY in gene regulation and virulence of the human pathogenStreptococcus pneumoniae. We constructed acodYmutant and examined the effect on gene and protein expression by microarray and two-dimensional differential gel electrophoresis analysis. The pneumococcal CodY regulon was found to consist predominantly of genes involved in amino acid metabolism but also several other cellular processes, such as carbon metabolism and iron uptake. By means of electrophoretic mobility shift assays and DNA footprinting, we showed that most of the targets identified are under the direct control of CodY. By mutating DNA predicted to represent the CodY box based on theL. lactisconsensus, we demonstrated that this sequence is indeed required for in vitro DNA binding to target promoters. Similar toL. lactis, DNA binding of CodY was enhanced in the presence of branched-chain amino acids, but not by GTP. We observed in experimental mouse models thatcodYis transcribed in the murine nasopharynx and lungs and is specifically required for colonization. This finding was underscored by the diminished ability of thecodYmutant to adhere to nasopharyngeal cells in vitro. Furthermore, we found thatpcpA, activated by CodY, is required for adherence to nasopharyngeal cells, suggesting a direct link between nutritional regulation and adherence. In conclusion, pneumococcal CodY predominantly regulates genes involved in amino acid metabolism and contributes to the early stages of infection, i.e., colonization of the nasopharynx.
Competitive Inhibition of Amino Acid Uptake Suppresses Chlamydial Growth: Involvement of the Chlamydial Amino Acid Transporter BrnQ
Authors: Braun Peter R. , Al-Younes Hesham , Gussmann Joscha , Klein Jeannette , Schneider Erwin , Meyer Thomas F.
Published: November 2007

Chlamydiaceaeare obligate intracellular bacterial pathogens that strictly depend on host metabolites, such as nucleotides, lipids, and amino acids. Depletion of amino acids in cell culture media results in abnormal chlamydial development in vitro. Surprisingly, enrichment of certain amino acids also retards chlamydial growth. Our experiments revealed that the antichlamydial effects are largely independent of changes in the host cell transcriptome or proteome and in the major signal transduction pathway modulated by amino acids, the mTOR (mammalian target of rapamycin) pathway. Furthermore, the chlamydial growth inhibition induced by leucine, isoleucine, methionine, or phenylalanine was completely reversed by concomitant addition of valine. In contrast, the growth inhibition induced by serine, glycine, or threonine was not reversed by valine addition. Functional characterization of the only predicted chlamydial transporter for branched-chain amino acids, BrnQ, revealed that it can be blocked by leucine, isoleucine, methionine, or phenylalanine but not by serine, glycine, or threonine. This chlamydial transporter is the only known BrnQ homolog possessing specificity for methionine, suggesting a unique strategy for methionine uptake among gram-negative bacteria. The antichlamydial effects of leucine, isoleucine, methionine, and phenylalanine could be explained as competitive inhibition of the BrnQ transporter and subsequent valine starvation.
Penicillin-Binding Proteins and Cell Wall Composition in β-Lactam-Sensitive and -Resistant Strains of
Staphylococcus sciuri
Authors: Zhou Yanjiao , Antignac Aude , Wu Shang Wei , Tomasz Alexander
Published: November 2007

A close homologue of the acquired
Staphylococcus aureus mecA
gene is present as a native gene in
Staphylococcus sciuri
. We determined the patterns of penicillin-binding proteins (PBPs) and the peptidoglycan compositions of several
S. sciuri
strains to explore the functions of this
mecA
homologue, named
pbpD
, in its native
S. sciuri
environment. The protein product of
pbpD
was identified as PBP4 with a molecular mass of 84 kDa, one of the six PBPs present in representatives of each of three subspecies of
S. sciuri
examined. PBP4 had a low affinity for nafcillin, reacted with a monoclonal antibody raised against
S. aureus
PBP2A, and was greatly overproduced in oxacillin-resistant clinical isolate
S. sciuri
SS37 and to a lesser extent in resistant laboratory mutant K1M200. An additional PBP inducible by oxacillin and corresponding to
S. aureus
PBP2A was identified in another oxacillin-resistant clinical isolate,
S. sciuri
K3, which harbors an
S. aureus
copy of
mecA
. Oxacillin resistance depended on the overtranscribed
S. sciuri pbpD
gene in strains SS37 and K1M200, while the resistance of strain K3 depended on the
S. aureus
copy of
mecA
. Our data provide evidence that both
S. aureus mecA
and
S. sciuri pbpD
can function as resistance determinants in either an
S. aureus
or an
S. sciuri
background and that the protein products of these genes,
S. aureus
PBP2A and
S. sciuri
PBP4, can participate in the biosynthesis of peptidoglycan, the muropeptide composition of which depends on the bacterium “hosting” the resistance gene.
Palaeogeothermal response and record of Late Mesozoic lithospheric thinning in the eastern North China Craton
Authors: Hu S. , Fu M. , Yang S. , Yuan Y. , Wang J.
Published: November 2007

The palaeotemperature recorded by vitrinite reflectance (
R
o
) in the pre-Cenozoic uplifted stratigraphic strata, and in Palaeozoic–Mesozoic remnant basins outside the Cenozoic depocentres, has not been overprinted by later thermal events in the eastern North China Craton (NCC). Based on downhole
R
o
data from the Palaeozoic and the Mesozoic subsections, we reconstruct the temperature gradients when the subsections reached their maximum palaeotemperatures in the Middle Triassic and the Cretaceous, and calculate the corresponding heat flow histories since the early Mesozoic. The temperature gradient and heat flow were much higher in the Cretaceous (35–43 °C km
−1
and 73–83 mW m
−2
, respectively) than in the Middle Triassic and at the present. The high palaeo-heat flow during the Late Mesozoic implies that the thickness of the ‘thermal’ lithosphere at that time was
c
. 65 km, about half the thickness of
c
. 135 km estimated for the Early Mesozoic. The change from a stable thermal regime to an active thermal regime took place during the Late Jurassic–Early Cretaceous (
c
. 110 Ma). This tectonothermal event was accompanied by extensive surface erosion, and is also evidenced in the areas adjacent to the NCC, such as the South Yellow Sea and East China Sea basins. Our study provides not only geothermal evidence for the Late Mesozoic lithospheric thinning, but also additional constraints on the thinning mechanism, which is currently being debated.
Fluid evolution and large-scale gold metallogeny during Mesozoic tectonic transition in the Jiaodong Peninsula, eastern China
Authors: Fan H.-R. , Hu F.-F. , Yang J.-H. , Zhai M.-G.
Published: November 2007

The Jiaodong Peninsula or eastern Shandong Province, the most important gold producing in region China, is located in the southeastern margin of the North China Craton. The gold deposits in the Jiaodong Peninsula are divided into three gold belts, from west to east, the Zhaoyuan–Laizhou, Penglai–Qixia and Muping–Rushan belts. The deposits occur as gold-bearing quartz veins and disseminated- and stockwork-style ores adjacent to fault zones. Most of the gold deposits can be classified in four stages: stage I, quartz–(minor) pyrite; stage II, pyrite–quartz–gold; stage III, quartz–base metal sulphide minerals; stage IV, quartz–carbonate. Ar–Ar ages, Rb–Sr isochrons, and hydrothermal zircon sensitive high-resolution ion microprobe U–Pb ages obtained from these deposits suggest a gold mineralization time of 120±10 Ma. The Sr–Nd isotopic compositions of pyrites and the associated rocks suggest that the ore-forming materials were probably derived from a mixed source. Fluid inclusion studies show that ore-forming fluids of gold deposits are consistent throughout the Jiaodong Peninsula, with similar mineralizing temperature and pressure conditions. Ore-forming fluids are characterized by H
2
O–CO
2
–NaCl±CH
4
. The optimal mineralizing temperature and pressure ranges are 170–335 °C and 0.7–2.5 kbar. Oxygen and hydrogen isotope data show that ore fluids are of magmatic origin. Gold deposits in the Jiaodong Peninsula formed in the same mineralizing–geodynamic conditions, and are related to the Mesozoic tectonic transition in the eastern North China Craton. Gold metallogeny is only one expression of the Mesozoic tectonic transition.
A mechanism for transforming buoyant North Chinese cratonic lithosphere to a denser equivalent for delamination
Authors: Deng J.-F. , Zhou M.-F. , Flower M. F. J. , Su S.-G. , Zhai M.-G. , Liu C. , Zhao G.-C. , Zhao X.-G. , Zhou S. , Wu Z.-W.
Published: November 2007

Two models have been proposed to explain lithospheric thinning of North Chinese cratonic lithosphere: (1) thermal erosion or/and chemical metasomatism, causing the lower part of the lithospheric mantle to be transformed into asthenosphere, a mechanism that implies thinning of relatively buoyant lithosphere; (2) the delamination of lithospheric mantle, in whole or part, along with the lowermost crust, as an effect of their increased densities relative to the underlying asthenosphere. This paper explores possible mechanisms whereby buoyant cratonic lithosphere might be transformed into a denser equivalent susceptible to delamination by the convecting asthenosphere. The Yanshan mobile belt in Eastern China developed in response to a combination of subduction and collision. Its apparent ‘counterclockwise’
P
–
T
–
t
metamorphic evolution suggests that underplated basaltic magma may have heated and, in turn, weakened the cool, rigid crust, allowing for compressional deformation and crustal thickening. Based on three independent lines of evidence (compressional deformation, the record of igneous activity, and lower crustal xenoliths) the thickness of continental crust is estimated to be about 50–65 km. Along with petrological and geochemical studies, thermal modelling shows that large-scale input of asthenospheric basaltic magma leads to granitoid partial melts in the lower crust, and the dominance of high-pressure eclogitic products following orogenic thickening may be necessary for eventual delamination to occur.
Mechanisms of the negative inotropic effects of sphingosine-1-phosphate on adult mouse ventricular myocytes
Authors: Landeen Lee K. , Dederko Dorothy A. , Kondo Colleen S. , Hu Betty S. , Aroonsakool Nakon , Haga Jason H. , Giles Wayne R.
Published: November 2007

Sphingosine-1-phosphate (S1P) induces a transient bradycardia in mammalian hearts through activation of an inwardly rectifying K+current ( IKACh) in the atrium that shortens action potential duration (APD) in the atrium. We have investigated probable mechanisms and receptor-subtype specificity for S1P-induced negative inotropy in isolated adult mouse ventricular myocytes. Activation of S1P receptors by S1P (100 nM) reduced cell shortening by ∼25% (vs. untreated controls) in field-stimulated myocytes. S1P1was shown to be involved by using the S1P1-selective agonist SEW2871 on myocytes isolated from S1P3-null mice. However, in these myocytes, S1P3can modulate a somewhat similar negative inotropy, as judged by the effects of the S1P1antagonist VPC23019 . Since S1P1activates Giexclusively, whereas S1P3activates both Giand Gq, these results strongly implicate the involvement of mainly Gi. Additional experiments using the IKAChblocker tertiapin demonstrated that IKAChcan contribute to the negative inotropy following S1P activation of S1P1(perhaps through Giβγsubunits). Mathematical modeling of the effects of S1P on APD in the mouse ventricle suggests that shortening of APD (e.g., as induced by IKACh) can reduce L-type calcium current and thus can decrease the intracellular Ca2+concentration ([Ca2+]i) transient. Both effects can contribute to the observed negative inotropic effects of S1P. In summary, these findings suggest that the negative inotropy observed in S1P-treated adult mouse ventricular myocytes may consist of two distinctive components: 1) one pathway that acts via Gito reduce L-type calcium channel current, blunt calcium-induced calcium release, and decrease [Ca2+]i; and 2) a second pathway that acts via Gito activate IKAChand reduce APD. This decrease in APD is expected to decrease Ca2+influx and reduce [Ca2+]iand myocyte contractility.
Role of Cu,Zn-SOD in the synthesis of endogenous vasodilator hydrogen peroxide during reactive hyperemia in mouse mesenteric microcirculation in vivo
Authors: Yada Toyotaka , Shimokawa Hiroaki , Morikawa Keiko , Takaki Aya , Shinozaki Yoshiro , Mori Hidezo , Goto Masami , Ogasawara Yasuo , Kajiya Fumihiko
Published: November 2007

We have recently demonstrated that endothelium-derived hydrogen peroxide (H2O2) is an endothelium-derived hyperpolarizing factor and that endothelial Cu/Zn-superoxide dismutase (SOD) plays an important role in the synthesis of endogenous H2O2 in both animals and humans. We examined whether SOD plays a role in the synthesis of endogenous H2O2 during in vivo reactive hyperemia (RH), an important regulatory mechanism. Mesenteric arterioles from wild-type and Cu,Zn-SOD−/− mice were continuously observed by a pencil-type charge-coupled device (CCD) intravital microscope during RH (reperfusion after 20 and 60 s of mesenteric artery occlusion) in the cyclooxygenase blockade under the following four conditions: control, catalase alone, NG-monomethyl-l-arginine (l-NMMA) alone, and l-NMMA + catalase. Vasodilatation during RH was significantly decreased by catalase or l-NMMA alone and was almost completely inhibited by l-NMMA + catalase in wild-type mice, whereas it was inhibited by l-NMMA and l-NMMA + catalase in the Cu,Zn-SOD−/− mice. RH-induced increase in blood flow after l-NMMA was significantly increased in the wild-type mice, whereas it was significantly reduced in the Cu,Zn-SOD−/− mice. In mesenteric arterioles of the Cu,Zn-SOD−/− mice, Tempol, an SOD mimetic, significantly increased the ACh-induced vasodilatation, and the enhancing effect of Tempol was decreased by catalase. Vascular H2O2 production by fluorescent microscopy in mesenteric arterioles after RH was significantly increased in response to ACh in wild-type mice but markedly impaired in Cu,Zn-SOD−/− mice. Endothelial Cu,Zn-SOD plays an important role in the synthesis of endogenous H2O2 that contributes to RH in mouse mesenteric smaller arterioles.
Increased susceptibility to hypoxic pulmonary hypertension in Bmpr2 mutant mice is associated with endothelial dysfunction in the pulmonary vasculature
Authors: Frank David B. , Lowery Jonathan , Anderson Lynda , Brink Monique , Reese Jeff , de Caestecker Mark
Published: November 2007

Patients with familial pulmonary arterial hypertension inherit heterozygous mutations of the type 2 bone morphogenetic protein (BMP) receptor BMPR2. To explore the cellular mechanisms of this disease, we evaluated the pulmonary vascular responses to chronic hypoxia in mice carrying heterozygous hypomorphic Bmpr2 mutations ( Bmpr2ΔEx2/+). These mice develop more severe pulmonary hypertension after prolonged exposure to hypoxia without an associated increase in pulmonary vascular remodeling or proliferation compared with wild-type mice. This is associated with defective endothelial-dependent vasodilatation and enhanced vasoconstriction in isolated intrapulmonary artery preparations. In addition, there is a selective decrease in hypoxia-induced, BMP-dependent, endothelial nitric oxide synthase expression and Smad signaling in the intact lungs and in cultured pulmonary microvascular endothelial cells from Bmpr2ΔEx2/+ mutant mice. These findings indicate that the pulmonary endothelium is a target of abnormal BMP signaling in Bmpr2ΔEx2/+ mutant mice and suggest that endothelial dysfunction contributes to their increased susceptibility to hypoxic pulmonary hypertension.
Altered carnitine homeostasis is associated with decreased mitochondrial function and altered nitric oxide signaling in lambs with pulmonary hypertension
Authors: Sharma Shruti , Sud Neetu , Wiseman Dean A. , Carter A. Lee , Kumar Sanjiv , Hou Yali , Rau Thomas , Wilham Jason , Harmon Cynthia , Oishi Peter , Fineman Jeffrey R. , Black Stephen M.
Published: November 2007

Utilizing aortopulmonary vascular graft placement in the fetal lamb, we have developed a model (shunt) of pulmonary hypertension that mimics congenital heart disease with increased pulmonary blood flow. Our previous studies have identified a progressive development of endothelial dysfunction in shunt lambs that is dependent, at least in part, on decreased nitric oxide (NO) signaling. The purpose of this study was to evaluate the possible role of a disruption in carnitine metabolism in shunt lambs and to determine the effect on NO signaling. Our data indicate that at 2 wk of age, shunt lambs have significantly reduced expression ( P < 0.05) of the key enzymes in carnitine metabolism: carnitine palmitoyltransferases 1 and 2 as well as carnitine acetyltransferase (CrAT). In addition, we found that CrAT activity was inhibited due to increased nitration. Furthermore, free carnitine levels were significantly decreased whereas acylcarnitine levels were significantly higher in shunt lambs ( P < 0.05). We also found that alterations in carnitine metabolism resulted in mitochondrial dysfunction, since shunt lambs had significantly decreased pyruvate, increased lactate, and a reduced pyruvate/lactate ratio. In pulmonary arterial endothelial cells cultured from juvenile lambs, we found that mild uncoupling of the mitochondria led to a decrease in cellular ATP levels and a reduction in both endothelial NO synthase-heat shock protein 90 (eNOS-HSP90) interactions and NO signaling. Similarly, in shunt lambs we found a loss of eNOS-HSP90 interactions that correlated with a progressive decrease in NO signaling. Our data suggest that mitochondrial dysfunction may play a role in the development of endothelial dysfunction and pulmonary hypertension and increased pulmonary blood flow.
Renal Vein Thrombosis: A Case Report
Authors: Bashir Riyaz , Tinkel Jodi , Malhotra Deepak
Published: November 2007

The presenting symptoms of acute renal vein thrombosis (RVT) can often be confused with those of nephrolithiasis. Delayed diagnosis and treatment of RVT can result in catastrophic complications, including loss of renal function and pulmonary embolism. A high clinical suspicion and early imaging with computed tomography or magnetic resonance imaging will allow early initiation of therapy and prevention of thrombus extension in patients with RVT.
Blood Glucose and Cerebrovascular Disease in Nondiabetic Patients
Authors: Nielson Christopher , Fleming Richard M.
Published: November 2007

The objective of this study was to determine if elevations in blood glucose, in a range classified as impaired fasting glucose, are associated with a greater incidence of cerebrovascular disease in nondiabetic patients. Morning blood glucose determinations were evaluated with respect to subsequent stroke using records from 28 477 nondiabetic patients. Strokes and transient ischemic attacks (TIA) were identified from ICD-9 coding for a new event more than a year after baseline glucose determinations. Of the patients studied, 593 suffered stroke or TIA over a total risk analysis time of 100 982 years. Higher baseline morning glucose (100 to 126 mg/dL vs under 100 mg/dL) was associated with 31% more diagnoses (2.4% vs 1.8%, P < .001). Incidence rate was 5.3 per 1000 patient-years for those patients with glucose over 100 mg/dL and 3.9 per 1000 patient-years for those with glucose under 100 mg/dL (P <.001). Kaplan-Meier analysis showed that elevated baseline glucose was associated with a progressive, increased risk with time. A Cox proportional hazards model with adjustment for age, body mass index, sex, creatinine, lipids, smoking, and medications showed that elevated fasting glucose was associated with an increased hazard for a new event (hazard ratio 1.24, 95% CI 1.05-1.46, glucose over 100 mg/dL vs under 100 mg/dL). Thus, patients with higher baseline blood glucose levels in the absence of diabetes and after adjustment for covariants have a significantly greater risk for development of cerebrovascular disease.
Prospective Assessment of Lower-Extremity Peripheral Arterial Disease in Diabetic Patients Using a Novel Automated Optical Device
Authors: Alnaeb Mohamad E. , Crabtree Vincent P. , Boutin Adrien , Mikhailidis Dimitri P. , Seifalian Alexander M. , Hamilton George
Published: November 2007

A new optical device based on the photoplethysmograph (PPG) method and an innovative algorithm for the assessment of lower-extremity peripheral arterial disease was investigated prospectively in patients with type II diabetes. This new functional PPG (fPPG) technique uses a cuffless functional test to assess diabetic peripheral arterial disease without operator dependency and the incompressible arteries, issues associated with ankle brachial pressure index (ABPI) measurement. Diabetic patients (n = 24; 47 legs; age, 70 ± 3 years) were recruited from the vascular clinic, and controls (n = 15; 30 legs; age, 66 ± 5 years) were recruited from the orthopedic outpatient clinic. All underwent resting ABPI, fPPG, and duplex angiography (DA) as “gold standard.” fPPG requires the placement of an optical probe on the toe for acquisition of pulsatile arterial perfusion for a period of 30 seconds with the leg in supine and raised at 45° positions. The data were analyzed, and indices were generated by an automated computer system. In those with diabetes, fPPG correlated significantly with DA (r = −.68, P < .01) and ABPI (r = −.65, P < .01). We also found a significant correlation between ABPI and DA (r = .81, P < .01). The analysis of the receiver operator curve showed that optimum sensitivity and specificity for ABPI and fPPG were 80% and 93% and 83% and 71%, respectively, against DA. This method uses changes in pulsatile arterial blood volume using a simple cuffless functional test. The fPPG investigation period was much shorter (5 minutes) with independence of operator skills, whereas ABPI took longer (10-15 minutes) and required operator experience. Although the fPPG results are promising, further improvement (eg, by incorporation of functional skin color and temperature changes) is required to improve the sensitivity and specificity of the system.
Intima-Media Thickness in Patients With Rheumatic Mitral Stenosis
Authors: Demircan Şenol , Sezgin Alpay T. , Baltali Mehmet , Gülcan Öner , Topcu Semra , Yigit Fatma , Erol Tansel , Turkoz Rıza , Muderrisoglu Haldun , Özin Bülent
Published: November 2007

The aim of the study was to determine carotid artery intima-media thickness (IMT) in patients with rheumatic mitral stenosis (RMS). Between January 2001 and December 2003, 112 consecutive patients who had been diagnosed with RMS were screened. Patients with known cerebrovascular disease, coronary artery disease, diabetes, hypertension, left ventricular hypertrophy, hyperlipidemia, abnormal laboratory results, smoking, or age over 50 years were excluded. Forty-eight patients (43 women, 5 men, mean age 39.7 ±8.3 years) with RMS without risk factors were enrolled in the study. Age- and sex-matched healthy individuals (n = 48; 43 women, 5 men, mean age 39.6 ±8.6 years) with normal echocardiographic findings constituted the control group. Carotid IMT was determined by using a high-resolution ultrasound system equipped with a 7-MHz imaging probe (Acuson 128 XP CI) with a computer measurement software. The mean common carotid artery IMT thicknesses both in the right (0.604 ±0.112 mm vs 0.521 ±0.072 mm) and in the left side (0.581 ±0.097 mm vs 0.516 ±0.065 mm) were significantly higher in patients with RMS than in the control group (p < 0.001). Backward stepwise logistic regression analysis identified RMS as independent predictors of increased IMT (OR, 17.25 (CI, 3.99 to 76.28), p <0.001). The present study demonstrated that RMS is associated with increased IMT. The findings indicate that in patients with RMS not only valvular but also systemic endothelium is damaged.
Injury Patterns in Professional Arena Football
Authors: Herbenick Michael A. , King Jonathan S. , Altobelli Grant , Nguyen Brian , Podesta Luga
Published: November 2007

Background

No studies to date have evaluated the injury patterns in professional arena football. The purpose of this study is to describe the characteristics of general injury patterns in the Arena Football League.

Hypotheses

(1) Game injury rates are higher than are practice injury rates, (2) a small number of injuries are related to collision with the boards, and (3) athletes playing on both offense and defense have higher injury rates than do athletes playing either offense or defense alone.

Study Design

Descriptive epidemiology study.

Methods

A retrospective review of injury data including 1199 injuries over a 4-year period from February 2002 to December 2005, inclusive of preseason and postseason practices and competition, was conducted. Data regarding the injured body part, position of the player, nature of injury, mechanism of injury, missed playing time, playing surface, and when the injury occurred were collected and analyzed.

Results

Injury rates during practice were 14.6 injuries per 1000 exposures and game injury rates were 111.3 per 1000 exposures. Few recorded injuries (2.2%) involved a collision with the sideline boards.

Conclusion

Game injury rates are higher than are practice injury rates. Athletes playing on both offense and defense did not have higher injury rates in games than did athletes playing either offense or defense. The sideline boards used in the Arena Football League did not appear to contribute dramatically to the injury rates. Despite the differences between arena and stadium football, Arena Football League injury patterns are similar to published collegiate football injury patterns.
Informing Dose-Finding Studies of Repetitive Transcranial Magnetic Stimulation to Enhance Motor Function: A Qualitative Systematic Review
Authors: Hiscock Andy , Miller Simon , Rothwell John , Tallis Raymond C. , Pomeroy Valerie M.
Published: November 2007

Objective. Repetitive transcranial magnetic stimulation (rTMS) of the lesioned hemisphere might enhance motor recovery after stroke, but the appropriate dose (parameters of rTMS) remains uncertain. The present review collates evidence of the effect of rTMS on corticospinal pathway excitability and motor function in healthy adults and in people after stroke. Methods. The authors searched MEDLINE and EMBASE (1996 to April 2007), their own collection of peer-reviewed articles, and the reference lists of included studies. They included healthy adults or people with stroke who received rTMS to the primary motor cortex to facilitate or inhibit contralateral corticospinal excitability or movement control. Findings. Of the 625 references identified, 37 studies were included with 455 healthy adults (34 studies) and 69 people with stroke (3 studies). For healthy adults, the effects of rTMS on corticospinal pathway excitability varied within each frequency, for example, 1 Hz rTMS was found to facilitate, inhibit, and have no effect on amplitude of motor-evoked potentials (MEPs). After stroke there was a trend for recovery of MEPs (ie, presence of MEPs) after 10 daily sessions of 3 Hz rTMS (one study). Motor function in healthy adults might be adversely affected by 1 Hz rTMS (two studies), whereas combined frequency rTMS was found to have no effect (one study). Interpretation . There is as yet insufficient published evidence to guide the dose of rTMS to the lesioned hemisphere after stroke to improve recovery of a paretic limb. Moreover, it is apparent that there is variability in response to rTMS in healthy adults. Dose-finding studies in groups of well-characterized stroke patients are needed.
Targeting of heat shock protein 32 (Hsp32)/heme oxygenase-1 (HO-1) in leukemic cells in chronic myeloid leukemia: a novel approach to overcome resistance against imatinib
Authors: Mayerhofer Matthias , Gleixner Karoline V. , Mayerhofer Julia , Hoermann Gregor , Jaeger Eva , Aichberger Karl J. , Ott Rene G. , Greish Khaled , Nakamura Hideaki , Derdak Sophia , Samorapoompichit Puchit , Pickl Winfried F. , Sexl Veronika , Esterbauer Harald , Schwarzinger Ilse , Sillaber Christian , Maeda Hiroshi , Valent Peter
Published: November 2007

Resistance toward imatinib and other BCR/ABL tyrosine kinase inhibitors remains an increasing clinical problem in the treatment of advanced stages of chronic myeloid leukemia (CML). We recently have identified the heat shock protein 32 (Hsp32)/heme oxygenase-1 (HO-1) as a BCR/ABL-dependent survival molecule in CML cells. We here show that silencing Hsp32/HO-1 in CML cells by an siRNA approach results in induction of apoptosis. Moreover, targeting Hsp32/HO-1 by either pegylated zinc protoporphyrine (PEG-ZnPP) or styrene maleic acid-micelle–encapsulated ZnPP (SMA-ZnPP) resulted in growth inhibition of BCR/ABL-transformed cells. The effects of PEG-ZnPP and SMA-ZnPP were demonstrable in Ba/F3 cells carrying various imatinib-resistant mutants of BCR/ABL, including the T315I mutant, which exhibits resistance against all clinically available BCR/ABL tyrosine kinase inhibitors. Growth-inhibitory effects of PEG-ZnPP and SMA-ZnPP also were observed in the CML-derived human cell lines K562 and KU812 as well as in primary leukemic cells obtained from patients with freshly diagnosed CML or imatinib-resistant CML. Finally, Hsp32/HO-1–targeting compounds were found to synergize with either imatinib or nilotinib in producing growth inhibition in imatinib-resistant K562 cells and in Ba/F3 cells harboring the T315I mutant of BCR/ABL. In summary, these data show that HO-1 is a promising novel target in imatinib-resistant CML.
The microtubule-targeting agent CA4P regresses leukemic xenografts by disrupting interaction with vascular cells and mitochondrial-dependent cell death
Authors: Petit Isabelle , Karajannis Matthias A. , Vincent Loic , Young Lauren , Butler Jason , Hooper Andrea T. , Shido Koji , Steller Hermann , Chaplin David J. , Feldman Eric , Rafii Shahin
Published: November 2007

Adhesion of leukemic cells to vascular cells may confer resistance to chemotherapeutic agents. We hypothesized that disruption of leukemic cell cytoskeletal stability and interference with vascular cell interactions would promote leukemic cell death. We demonstrate that low and nontoxic doses of microtubule-destabilizing agent combretastatin-A4-phosphate (CA4P) inhibit leukemic cell proliferation in vitro and induce mitotic arrest and cell death. Treatment of acute myeloid leukemias (AMLs) with CA4P leads to disruption of mitochondrial membrane potential, release of proapoptotic mitochondrial membrane proteins, and DNA fragmentation, resulting in cell death in part through a caspase-dependent manner. Furthermore, CA4P increases intracellular reactive oxygen species (ROS), and antioxidant treatment imparts partial protection from cell death, suggesting that ROS accumulation contributes to CA4P-induced cytotoxicity in AML. In vivo, CA4P inhibited proliferation and circulation of leukemic cells and diminished the extent of perivascular leukemic infiltrates, prolonging survival of mice that underwent xenotransplantation without inducing hematologic toxicity. CA4P decreases the interaction of leukemic cells with neovessels by down-regulating the expression of the adhesion molecule VCAM-1 thereby augmenting leukemic cell death. These data suggest that CA4P targets both circulating and vascular-adherent leukemic cells through mitochondrial damage and down-regulation of VCAM-1 without incurring hematologic toxicities. As such, CA4P provides for an effective means to treat refractory organ-infiltrating leukemias.
Globin switches in yolk sac–like primitive and fetal-like definitive red blood cells produced from human embryonic stem cells
Authors: Qiu Caihong , Olivier Emmanuel N. , Velho Michelle , Bouhassira Eric E.
Published: November 2007

We have previously shown that coculture of human embryonic stem cells (hESCs) for 14 days with immortalized fetal hepatocytes yields CD34+ cells that can be expanded in serum-free liquid culture into large numbers of megaloblastic nucleated erythroblasts resembling yolk sac–derived cells. We show here that these primitive erythroblasts undergo a switch in hemoglobin (Hb) composition during late terminal erythroid maturation with the basophilic erythroblasts expressing predominantly Hb Gower I (ζ2ϵ2) and the orthochromatic erythroblasts hemoglobin Gower II (α2ϵ2). This suggests that the switch from Hb Gower I to Hb Gower II, the first hemoglobin switch in humans is a maturation switch not a lineage switch. We also show that extending the coculture of the hESCs with immortalized fetal hepatocytes to 35 days yields CD34+ cells that differentiate into more developmentally mature, fetal liver–like erythroblasts, that are smaller, express mostly fetal hemoglobin, and can enucleate. We conclude that hESC-derived erythropoiesis closely mimics early human development because the first 2 human hemoglobin switches are recapitulated, and because yolk sac–like and fetal liver–like cells are sequentially produced. Development of a method that yields erythroid cells with an adult phenotype remains necessary, because the most mature cells that can be produced with current systems express less than 2% adult β-globin mRNA.
Inferring biological functions and associated transcriptional regulators using gene set expression coherence analysis
Authors: Kim Tae-Min , Chung Yeun-Jun , Rhyu Mun-Gan , Ho Jung Myeong
Published: November 2007

Background

Gene clustering has been widely used to group genes with similar expression pattern in microarray data analysis. Subsequent enrichment analysis using predefined gene sets can provide clues on which functional themes or regulatory sequence motifs are associated with individual gene clusters. In spite of the potential utility, gene clustering and enrichment analysis have been used in separate platforms, thus, the development of integrative algorithm linking both methods is highly challenging.

Results

In this study, we propose an algorithm for discovery of molecular functions and elucidation of transcriptional logics using two kinds of gene information, functional and regulatory motif gene sets. The algorithm, termed gene set expression coherence analysis first selects functional gene sets with significantly high expression coherences. Those candidate gene sets are further processed into a number of functionally related themes or functional clusters according to the expression similarities. Each functional cluster is then, investigated for the enrichment of transcriptional regulatory motifs using modified gene set enrichment analysis and regulatory motif gene sets. The method was tested for two publicly available expression profiles representing murine myogenesis and erythropoiesis. For respective profiles, our algorithm identified myocyte- and erythrocyte-related molecular functions, along with the putative transcriptional regulators for the corresponding molecular functions.

Conclusion

As an integrative and comprehensive method for the analysis of large-scaled gene expression profiles, our method is able to generate a set of testable hypotheses: the transcriptional regulator X regulates function Y under cellular condition Z. GSECA algorithm is implemented into freely available software package.