bluuebunny/crossref_metadata_2025_split huggingface dataset:
Loop ultrastructure and development in Recent Megathiridoidea, with description of a new genus, Joania (type species Terebratula cordata Risso, 1826)
Authors: Alvarez Fernando , Brunton C. Howard C. , Long Sarah L. 
Published: August 2008

ABSTRACTThe loop configuration, structure and growth are studied in a series of megathiridoid dorsal valves ranging in length from 0·7 to 6 mm. The structure of the posterior and anterior sectors of the descending lamellae and their relationships with the socket ridges, dorsal septa and dorsal valve floor, are studied, illustrated and described. Detailed studies show that internal structures display great variability. In the megathiridoids the lamellae of more typical terebratulide loops are replaced by partially developed loops in early developmental stages, resulting in a mix of free sections of loop together with sections where the lophophore rests directly on the epithelium of the valve floor. Comments on the ecology of the megathiridoid species are included and relate their unusually wide gapes, which position their lophophores fully accessible to the open sea, with their strong lophophore attachments and loss of typical free loops. The new genus Joania (type species Terebratula cordata Risso, 1826) is erected for those Argyrotheca which, although having a typical megathiridoid brachidium, differ in their adult crural development, their narrow hinge line, their prominent cardinal process, their characteristic dorsal median septum and their tuberculate radial ridges terminating anteriorly in tubercles.
Lower Permian brachiopods from Oman: their potential as climatic proxies
Authors: Angiolini L. , Darbyshire D. P. F. , Stephenson M. H. , Leng M. J. , Brewer T. S. , Berra F. , Jadoul F. 
Published: August 2008

ABSTRACTThe Lower Permian of the Haushi basin, Interior Oman (Al Khlata Formation to Saiwan Formation/lower Gharif member) records climate change from glaciation, through marine sedimentation in the Haushi sea, to subtropical desert. To investigate the palaeoclimatic evolution of the Haushi Sea we used O, C, and Sr isotopes from 31 brachiopod shells of eight species collected bed by bed within the type-section of the Saiwan Formation. We assessed diagenesis by scanning electron microscopy of ultrastructure, cathodoluminescence, and geochemistry, and rejected fifteen shells not meeting specific preservation criteria. Spiriferids and spiriferinids show better preservation of the fibrous secondary layer than do orthotetids and productids and are therefore more suitable for isotopic analysis. δ18O of −3·7 to −3·1℅ from brachiopods at the base of the Saiwan Formation are probably related to glacial meltwater. Above this, an increase in δ18O may indicate ice accumulation elsewhere in Gondwana or more probably that the Haushi sea was an evaporating embayment of the Neotethys Ocean. δ13C varies little and is within the range of published data: its trend towards heavier values is consistent with increasing aridity and oligotrophy. Saiwan Sr isotope signatures are less radiogenic than those of the Sakmarian LOWESS seawater curve, which is based on extrapolation between few data points. In the scenario of evaporation in a restricted Haushi basin, the variation in Sr isotope composition may reflect a fluvial component.
Earliest Silurian faunal survival and recovery after the end Ordovician glaciation: evidence from the brachiopods
Authors: Cocks L. Robin M. , Jia-yu Rong 
Published: August 2008

ABSTRACTEarliest Silurian (basal Llandovery) brachiopod faunas are surveyed and listed from around the globe, and divided between Lower Rhuddanian and Upper Rhuddanian occurrences. 60 genera are known from the Lower Rhuddanian within 20 superfamilies and there are 87 genera in 25 superfamilies in the Upper Rhuddanian. The 29 areas surveyed span the globe, both latitudinally and longitudinally. Only six superfamilies are Lazarus taxa which are known both from the Ordovician and Middle Llandovery (Aeronian) and later rocks but have not been recorded from the Rhuddanian. These are surprising results, since many previous studies have inferred that the Rhuddanian was a time of very sparse faunas. The global warming that followed the latest Ordovician (Hirnantian) ice age did not proceed quickly, with an ice-cap probably present through at least the Llandovery. There is a marked absence of Lower Rhuddanian bioherms even at low palaeolatitudes; however, the ecological recovery rate was far faster than that following the end-Permian mass extinction event. The partitioning of the Rhuddanian shelf faunas into well-defined benthic assemblages progressed slowly over the interval.
Relationship between δ18O and minor element composition of Terebratalia transversa
Authors: Cusack Maggie , Parkinson David , Pérez-Huerta Alberto , England Jennifer , Curry Gordon B. , Fallick Anthony E. 
Published: August 2008

ABSTRACTWith their extensive fossil record and shells of stable low-Mg calcite, rhynchonelliform brachiopods are attractive sources of climate information via seawater temperature proxies such as stable oxygen isotope composition. In Terebratalia transversa (Sowerby) there is a progression towards oxygen isotope equilibrium in the calcite of the innermost secondary layer. This study confirms the lack of any vital effects influencing oxygen isotope composition of T. transversa, even in specialised areas of the innermost secondary layer. Calcite Mg/Ca ratio is another potential seawater temperature proxy, that has the advantage of not being influenced by salinity. Mg concentrations measured by electron microprobe analyses indicate that there is no concomitant decrease in Mg concentration towards the inner secondary layer, associated with the progressive shift towards oxygen isotope equilibrium. Mg distribution is heterogeneous throughout the shell and correlates with that of sulphur, which may be a proxy for organic components, suggesting that some of the Mg may not be in the calcite lattice. It is essential therefore, to determine the chemical environment of the magnesium ions to avoid any erroneous temperature extrapolations in brachiopods or any other calcite biomineral.
Left ventricular systolic and diastolic dyssynchrony in coronary artery disease with preserved ejection fraction
Authors: Lee Pui-Wai , Zhang Qing , Yip Gabriel Wai-Kwok , Wu LiWen , Lam Yat-yin , Wu Eugene B. , Yu Cheuk-Man 
Published: August 2008

The present study aims to evaluate LV (left ventricular) mechanical dyssynchrony in CAD (coronary artery disease) with preserved and depressed EF (ejection fraction). Echocardiography with TDI (tissue Doppler imaging) was performed in 311 consecutive CAD patients (94 had preserved EF ≥50% and 217 had depressed EF &lt;50%) and 117 healthy subjects to determine LV systolic and diastolic dyssynchrony by measuring Ts-SD (S.D. of time to peak myocardial systolic velocity during the ejection period) and Te-SD (S.D. of time to peak myocardial early diastolic velocity during the filling period) respectively, using a six-basal/six-mid-segmental model. In CAD patients with preserved EF, both Ts-SD (32.2±17.3 compared with 17.7±8.6 ms; P&lt;0.05) and Te-SD (26.2±13.6 compared with 20.3±8.1 ms; P&lt;0.05) were significantly prolonged when compared with controls, although they were less prolonged than CAD patients with depressed EF (Ts-SD, 37.8±16.5 ms; and Te-SD, 36.0±23.9 ms; both P&lt;0.005). Patients with preserved EF who had no prior MI (myocardial infarction) had Ts-SD (32.9±17.5 ms) and Te-SD (28.6±14.8 ms) prolonged to a similar extent (P=not significant) to those with prior MI (Ts-SD, 28.4±16.8 ms; and Te-SD, 25.5±15.0 ms). Patients with class III/IV angina or multi-vessel disease were associated with more severe mechanical dyssynchrony (P&lt;0.05). Furthermore, the majority of patients with mechanical dyssynchrony had narrow QRS complexes in those with preserved EF. This is in contrast with patients with depressed EF in whom systolic and diastolic dyssynchrony were more commonly associated with wide QRS complexes. In conclusion, LV mechanical dyssynchrony is evident in CAD patients with preserved EF, although it was less prevalent than those with depressed EF. In addition, mechanical dyssynchrony occurred in CAD patients without prior MI and narrow QRS complexes.
RBC Adhesion to Vascular Endothelial Cells: More Potent than RBC Aggregation in Inducing Circulatory Disorders
Authors: YEDGAR SAUL , KAUL DHANANJAY K. , BARSHTEIN GREGORY 
Published: August 2008

ABSTRACTGrowing evidence has suggested that the adhesion of red blood cells (RBCs) to blood vessel wall endothelial cells (ECs) is a potent catalyst of microcirculatory disorders, but direct in vivo documentation has been lacking. In a recent study we have demonstrated the elevation of vascular resistance by RBCs with increased adhesion to ECs and normal deformability in the absence of aggregation. Unlike the previous chapter (i.e., the “point”), the findings and considerations discussed in this chapter (the “counterpoint) imply that RBC/EC adhesion is a more potent determinant of circulatory disorders than RBC aggregation.
Increased Arachidonic Acid‐Induced Thromboxane Generation Impairs Skeletal Muscle Arteriolar Dilation with Genetic Dyslipidemia
Authors: GOODWILL ADAM. G. , STAPLETON PHOEBE A. , JAMES MILINDA E. , D'AUDIFFRET ALEXANDRE C. , FRISBEE JEFFERSON C. 
Published: August 2008

ABSTRACTObjective:The aim of this study was to determine if arachidonic acid (AA)‐induced skeletal muscle arteriolar dilation is altered with hypercholesterolemia in ApoE and low‐density lipoprotein receptor (LDLR) gene deletion mice fed a normal diet. This study also determined contributors to altered AA‐induced dilation between dyslipidemic mice and controls, C57/Bl/6J (C57).Methods:Gracilis muscle arterioles were isolated, with mechanical responses assessed following a challenge with AA under control conditions and after elements of AA metabolism pathways were inhibited. Conduit arteries from each strain were used to assess AA‐induced production of PGI2and TxA2.Results:Arterioles from ApoE and LDLR exhibited a blunted dilation to AA versus C57. While responses were cyclo‐oxygenase‐dependent in all strains, inhibition of thromboxane synthase or blockade of PGH2/TxA2receptors improved dilation in ApoE and LDLR only. AA‐induced generation of PGI2was comparable across strains, although TxA2generation was increased in ApoE and LDLR. Arteriolar reactivity to PGI2and TxA2was comparable across strains. Treatment with TEMPOL improved dilation and reduced TxA2production with AA in ApoE and LDLR.Conclusions:These results suggest that AA‐induced arteriolar dilation is constrained in ApoE and LDLR via an increased production of TxA2. While partially due to elevated oxidant stress, additional mechanisms contribute that are independent of acute alterations in oxidant tone.
The solution structure of the C‐terminal domain of NfeD reveals a novel membrane‐anchored OB‐fold
Authors: Kuwahara Yohta , Ohno Ayako , Morii Taichi , Yokoyama Hideshi , Matsui Ikuo , Tochio Hidehito , Shirakawa Masahiro , Hiroaki Hidekazu 
Published: August 2008

AbstractNodulation formation efficiency D (NfeD) is a member of a class of membrane‐anchored ClpP‐class proteases. There is a second class of NfeD homologs that lack the ClpP domain. The genes of both NfeD classes usually are part of an operon that also contains a gene for a prokaryotic homolog of stomatin. (Stomatin is a major integral‐membrane protein of mammalian erythrocytes.) Such NfeD/stomatin homolog gene pairs are present in more than 290 bacterial and archaeal genomes, and their protein products may be part of the machinery used for quality control of membrane proteins. Herein, we report the structure of the isolated C‐terminal domain of PH0471, a Pyrococcus horikoshii NfeD homolog, which lacks the ClpP domain. This C‐terminal domain (termed NfeDC) contains a five‐strand β‐barrel, which is structurally very similar to the OB‐fold (oligosaccharide/oligonucleotide–binding fold) domain. However, there is little sequence similarity between it and previously characterized OB‐fold domains. The NfeDC domain lacks the conserved surface residues that are necessary for the binding of an OB‐fold domain to DNA/RNA, an ion. Instead, its surface is composed of residues that are uniquely conserved in NfeD homologs and that form the structurally conserved surface turns and β‐bulges. There is also a conserved tryptophan present on the surface. We propose that, in general, NfeDC domains may interact with other spatially proximal membrane proteins and thereby regulate their activities.
Assignment‐free solution NMR method reveals CesT as an unswapped homodimer
Authors: Rumpel Sigrun , Lakshmi Raghavendran , Becker Stefan , Zweckstetter Markus 
Published: August 2008

AbstractThe X‐ray structure of the homodimeric chaperone CesT is the only structure among the type three secretion system (TTSS) chaperones that shows a domain swap. This swap has potential importance for the mechanism of effector translocation through a TTSS. Here we present two nuclear magnetic resonance strategies exploiting pre‐existing structural models and residual dipolar couplings (RDCs), which reveal the unswapped 35.4‐kDa dimer to be present in solution. Particularly efficient is the discrimination of a swapped and unswapped structural state performed simultaneously to automatic backbone assignment using only HN‐RDCs and carbonyl backbone chemical shifts. This direct approach may prove to be generally useful to rapidly differentiate two structural models.
Electrostatic contributions drive the interaction between Staphylococcus aureus protein Efb‐C and its complement target C3d
Authors: Haspel Nurit , Ricklin Daniel , Geisbrecht Brian V. , Kavraki Lydia E. , Lambris John D. 
Published: August 2008

AbstractThe C3–inhibitory domain of Staphylococcus aureus extracellular fibrinogen‐binding protein (Efb‐C) defines a novel three‐helix bundle motif that regulates complement activation. Previous crystallographic studies of Efb‐C bound to its cognate subdomain of human C3 (C3d) identified Arg‐131 and Asn‐138 of Efb‐C as key residues for its activity. In order to characterize more completely the physical and chemical driving forces behind this important interaction, we employed in this study a combination of structural, biophysical, and computational methods to analyze the interaction of C3d with Efb‐C and the single‐point mutants R131A and N138A. Our results show that while these mutations do not drastically affect the structure of the Efb‐C/C3d recognition complex, they have significant adverse effects on both the thermodynamic and kinetic profiles of the resulting complexes. We also characterized other key interactions along the Efb‐C/C3d binding interface and found an intricate network of salt bridges and hydrogen bonds that anchor Efb‐C to C3d, resulting in its potent complement inhibitory properties.
An electrostatic network and long‐range regulation of Src kinases
Authors: Ozkirimli Elif , Yadav Shalini S. , Miller W. Todd , Post Carol Beth 
Published: August 2008

AbstractThe regulatory mechanism of Src tyrosine kinases includes conformational activation by a change in the catalytic domain tertiary structure and in domain–domain contacts between the catalytic domain and the SH2/SH3 regulatory domains. The kinase is activated when tyrosine phosphorylation occurs on the activation loop, but without phosphorylation of the C‐terminal tail. Activation also occurs by allostery when contacts between the catalytic domain (CD) and the regulatory SH3 and SH2 domains are released as a result of exogenous protein binding. The aim of this work is to examine the proposed role of an electrostatic network in the conformational transition and to elucidate the molecular mechanism for long‐range, allosteric conformational activation by using a combination of experimental enzyme kinetics and nonequilibrium molecular dynamics simulations. Salt dependence of the induction phase is observed in kinetic assays and supports the role of an electrostatic network in the transition. In addition, simulations provide evidence that allosteric activation involves a concerted motion coupling highly conserved residues, and spanning several nanometers from the catalytic site to the regulatory domain interface to communicate between the CD and the regulatory domains.
Flexible dosing of Tincture of Opium in the management of opioid withdrawal: pharmacokinetics and pharmacodynamics
Authors: Somogyi Andrew A. , Larsen Mie , Abadi Reza M. , Jittiwutikarn Jaroon , Ali Robert , White Jason M. 
Published: August 2008

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT • In parts of South‐East Asia, Tincture of Opium (TOP) is a culturally acceptable alternative to methadone in the treatment of opioid withdrawal.• We have previously shown that TOP has a therapeutic effect when administered to opioid‐dependent patients in Northern Thailand.• However, before TOP could be used clinically, an evaluation of the dosing regimen had to be undertaken. WHAT THIS STUDY ADDS • This study extends the previous study by evaluating the clinical effectiveness of a dosing regimen in which the TOP dose was adjusted according to prior self‐reported opium use.• Adequate suppression of withdrawal can be achieved, with minimal side‐effects, in opioid‐dependent individuals receiving flexible dosing of TOP.• This study provides preliminary evidence for the effectiveness of TOP in the management of opioid withdrawal.AIMSThe aim was to evaluate the clinical effectiveness, pharmacodynamics and pharmacokinetics of a range of Tincture of Opium (TOP) doses in the management of opioid withdrawal.METHODSForty‐five opium‐dependent Thai subjects were allocated to three dosing groups (6.66, 13.3 and 20 mg morphine equivalents, twice daily) depending on their self‐reported prior opium use. On day 5 of dosing subjects underwent an interdosing interval study where blood, withdrawal scores, heart rate and blood pressure (BP) were collected at 0, 1, 3 and 8 h. Plasma morphine concentrations were quantified by high‐performance liquid chromatography, and plasma morphine‐3‐glucuronide (M3G) and morphine‐6‐glucuronide (M6G) concentrations by LCMS.RESULTSThirty‐two subjects completed the study. Withdrawal scores were low for all subjects (range 9–23% of maximum response). There were dose‐dependent changes in both systolic and diastolic BP (P = 0.021 and P = 0.01, respectively), but these were not considered clinically significant. There were no effects of dose on respiratory rate. Plasma morphine concentrations changed significantly across the interdosing interval (P = 0.0001), rising to a maximum at 1 h after dosing. Plasma morphine concentrations also differed according to dose (P < 0.05). The mean ratios of the morphine glucuronides were found to be: M3G/M6G = 7.7, M3G/morphine = 35.6 and M6G/morphine = 4.9, values comparable to those previously reported.CONCLUSIONThe management of opioid withdrawal can be achieved, with minimal adverse effects, by using flexible dosing of TOP.
Intravitreal bevacizumab (Avastin®) injection for neovascular glaucoma: a survey on 23 cases throughout 12‐month follow‐up
Authors: Costagliola Ciro , Cipollone Ugo , Rinaldi Michele , Della Corte Michele , Semeraro Francesco , Romano Mario R. 
Published: August 2008

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT • Neovascular glaucoma (NVG) is a form of secondary glaucoma in which fibrovascular tissue grows, leading to progressive angle closure with elevation of intraocular pressure.• NVG is poorly responsive to the conventional treatment and has a poor visual prognosis. WHAT THIS STUDY ADDS • The present study, performed in 23 patients (26 eyes), shows that three intravitreal injections of bevacizumab scheduled at 4‐week intervals are able to result in significant regression of neovascularization, with best response achieved after the third injection.• Our study suggests that bevacizumab is effective in rapidly controlling neovascularization and in preventing angle closure.• Improvements are demonstrated to last at 12 months, and additional interest comes from the lack of any significant adverse effects.AIMSNeovascular glaucoma (NVG) represents one of the most severe forms of secondary glaucoma, caused by a number of ocular and systemic conditions, which share the common element of retinal ischaemia/hypoxia that initiates the subsequent release of angiogenesis factors, with consequent development of new abnormal vessels through the ciliary body. The aim was to examine the potential efficacy and safety of intravitreal injection of bevacizumab (IVB) (Avastin®) in the treatment of NVG in patients who had already undergone the standard retinal ablative procedure.METHODSThis was a prospective pilot trial. Clinical data of 26 eyes from 23 patients, including diagnosis, visual acuity, iris fluorescein angiography stage and intraocular pressure (IOP), were collected. Three injections of bevacizumab were scheduled for each recruited eye at 4‐week intervals from the start. All investigations were repeated the day before the IVB (1.25 mg/0.05 ml) and at the 1‐, 3‐, 6‐, 9‐ and 12‐month follow‐up.RESULTSRegression of corneal oedema together with significant pain reduction was achieved in all eyes already after the first IVB, without any noteworthy improvement of visual acuity. At the end of the scheduled protocol (three IVB), regression of iris neovascularization was documented in all patients, together with significant improvement of visual acuity. The IOP reduction from baseline ranged from 30 to 0 mmHg (12.1 ± 8 mmHg).CONCLUSIONSIntravitreal bevacizumab, as adjunctive treatment to the standard retinal ablative procedure, seems promising for the management of conditions responsible of retinal ischaemia/hypoxia associated with NVG.
Source–sink dynamics sustain central stonerollers (Campostoma anomalum) in a heavily urbanized catchment
Authors: WAITS ERIC R. , BAGLEY MARK J. , BLUM MICHAEL J. , MCCORMICK FRANK H. , LAZORCHAK JAMES M. 
Published: August 2008

Summary1. The influence of spatial structure on population dynamics within river–stream networks is poorly understood. Utilizing spatially explicit analyses of temporal genetic variance, we tested whether persistence of central stonerollers (Campostoma anomalum) reflects differences in habitat quality and location within a highly modified urban catchment in southwestern Ohio, U.S.A.2. Estimates of genetic diversity did not vary with habitat quality. Nevertheless, evidence of weak but temporally stable genetic structure, location‐dependent effective population sizes and rates of immigration among sites, together suggest that persistence of central stonerollers within the catchment may be attributable to source–sink dynamics driven by habitat heterogeneity.3. Under this scenario, migrant‐pool colonization from areas of relatively high habitat quality in the upper catchment sustains the presence of central stonerollers at degraded sites in the main stem and dampens population subdivision within the catchment. However, because intact habitat is restricted to the upper portion of the catchment, it is not possible to preclude net downstream dispersal as a mechanism contributing to source–sink dynamics. The slight genetic structure that persists appears to reflect weak isolation by distance diminished by high rates of immigration.4. This study suggests that without a systems perspective of the conditions that sustain populations in degraded waterways, environmental assessments may underestimate levels of impairment. Conservation and management of stream fishes could be improved by maintaining habitat in areas that are net exporters of migrants or by remediation of impaired habitat.