bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification of a Ca
2+
-Binding Domain in the Rubella Virus Nonstructural Protease
Authors: Zhou Yubin , Tzeng Wen-Pin , Yang Wei , Zhou Yumei , Ye Yiming , Lee Hsiau-wei , Frey Teryl K. , Yang Jenny
Published: May 2007

The rubella virus (RUB) nonstructural protein (NS) open reading frame (ORF) encodes a polypeptide precursor that is proteolytically self cleaved into two replicase components involved in viral RNA replication. A putative EF-hand Ca
2+
-binding motif that was conserved across different genotypes of RUB was predicted within the nonstructural protease that cleaves the precursor by using bioinformatics tools. To probe the metal-binding properties of this motif, we used an established grafting approach and engineered the 12-residue Ca
2+
-coordinating loop into a non-Ca
2+
-binding scaffold protein, CD2. The grafted EF-loop bound to Ca
2+
and its trivalent analogs Tb
3+
and La
3+
with
K

d

s of 214, 47, and 14 μM, respectively. Mutations (D1210A and D1217A) of two of the potential Ca
2+
-coordinating ligands in the EF-loop led to the elimination of Tb
3+
binding. Inductive coupled plasma mass spectrometry was used to confirm the presence of Ca
2+
([Ca
2+
]/[protein] = 0.7 ± 0.2) in an NS protease minimal metal-binding domain, RUBCa, that spans the EF-hand motif. Conformational studies on RUBCa revealed that Ca
2+
binding induced local conformational changes and increased thermal stability (Δ
T

m

= 4.1°C). The infectivity of an RUB infectious cDNA clone containing the mutations D1210A/D1217A was decreased by ∼20-fold in comparison to the wild-type (wt) clone, and these mutations rapidly reverted to the wt sequence. The NS protease containing these mutations was less efficient at precursor cleavage than the wt NS protease at 35°C, and the mutant NS protease was temperature sensitive at 39°C, confirming that the Ca
2+
-binding loop played a structural role in the NS protease and was specifically required for optimal stability under physiological conditions.
Dendritic Cells Infected withvpr-Positive Human Immunodeficiency Virus Type 1 Induce CD8+T-Cell Apoptosis via Upregulation of Tumor Necrosis Factor Alpha
Authors: Majumder Biswanath , Venkatachari Narasimhan J. , Schafer Elizabeth A. , Janket Michelle L. , Ayyavoo Velpandi
Published: May 2007

Human immunodeficiency virus type 1 (HIV-1) viral protein R (Vpr) plays a crucial role in viral replication and pathogenesis by inducing cell cycle arrest, apoptosis, translocation of preintegration complex, potentiation of glucocorticoid action, impairment of dendritic cell (DC) maturation, and T-cell activation. Recent studies involving the direct effects of Vpr on DCs and T cells indicated that HIV-1 containing Vpr selectively impairs phenotypic maturation, cytokine network, and antigen presentation in DCs and dysregulates costimulatory molecules and cytokine production in T cells. Here, we have further investigated the indirect effect of HIV-1 Vpr+virus-infected DCs on the bystander CD8+T-cell population. Our results indicate that HIV-1 Vpr+virus-infected DCs dysregulate CD8+T-cell proliferation and induce apoptosis. Vpr-containing virus-infected DC-mediated CD8+T-cell killing occurred in part through enhanced tumor necrosis factor alpha production by infected DCs and subsequent induction of death receptor signaling and activation of the caspase 8-dependent pathway in CD8+T cells. Collectively, these results provide evidence that Vpr could be one of the important contributors to the host immune escape by HIV-1 through its ability to dysregulate both directly and indirectly the DC biology and T-cell functions.
Ebola Virus Glycoprotein 1: Identification of Residues Important for Binding and Postbinding Events
Authors: Brindley Melinda A. , Hughes Laura , Ruiz Autumn , McCray Paul B. , Sanchez Anthony , Sanders David A. , Maury Wendy
Published: May 2007

The filoviruses Ebola virus (EBOV) and Marburg virus (MARV) are responsible for devastating hemorrhagic fever outbreaks. No therapies are available against these viruses. An understanding of filoviral glycoprotein 1 (GP1) residues involved in entry events would facilitate the development of antivirals. Towards this end, we performed alanine scanning mutagenesis on selected residues in the amino terminus of GP1. Mutant GPs were evaluated for their incorporation onto feline immunodeficiency virus (FIV) particles, transduction efficiency, receptor binding, and ability to be cleaved by cathepsins L and B. FIV virions bearing 39 out of 63 mutant glycoproteins transduced cells efficiently, whereas virions bearing the other 24 had reduced levels of transduction. Virions pseudotyped with 23 of the poorly transducing GPs were characterized for their block in entry. Ten mutant GPs were very poorly incorporated onto viral particles. Nine additional mutant GPs (G87A/F88A, K114A/K115A, K140A, G143A, P146A/C147A, F153A/H154A, F159A, F160A, and Y162A) competed poorly with wild-type GP for binding to permissive cells. Four of these nine mutants (P146A/C147A, F153A/H154A, F159A, and F160A) were also inefficiently cleaved by cathepsins. An additional four mutant GPs (K84A, R134A, D150A, and E305/E306A) that were partially defective in transduction were found to compete effectively for receptor binding and were readily cleaved by cathepsins. This finding suggested that this latter group of mutants might be defective at a postbinding, cathepsin cleavage-independent step. In total, our study confirms the role of some GP1 residues in EBOV entry that had previously been recognized and identifies for the first time other residues that are important for productive entry.
Ultracentrifugation of Serum Samples Allows Detection of Hepatitis C Virus RNA in Patients with Occult Hepatitis C
Authors: Bartolomé Javier , López-Alcorocho Juan Manuel , Castillo Inmaculada , Rodríguez-Iñigo Elena , Quiroga Juan Antonio , Palacios Ricardo , Carreño Vicente
Published: May 2007

Occult hepatitis C virus (HCV) infection of patients with abnormal liver function tests of unknown origin who are anti-HCV and serum HCV RNA negative but who have HCV RNA in the liver has been described. As HCV replicates in the liver cells of these patients, it could be that the amount of circulating viral particles is under the detection limit of the most sensitive techniques. To prove this hypothesis, serum samples from 106 patients with occult HCV infection were analyzed. Two milliliters of serum was ultracentrifuged over a 10% sucrose cushion for 17 h at 100,000 ×gav, where av means average, and HCV RNA detection was performed by strand-specific real-time PCR. Out of the 106 patients, 62 (58.5%) had detectable serum HCV RNA levels after ultracentrifugation, with a median load of 70.5 copies/ml (range, 18 to 192). Iodixanol density gradient studies revealed that HCV RNA was positive at densities of 1.03 to 1.04 and from 1.08 to 1.19 g/ml, which were very similar to those found in the sera of patients with classical chronic HCV infection. Antigenomic HCV RNA was found in the livers of 56 of 62 (90.3%) patients with detectable serum HCV RNA levels after ultracentrifugation, compared to 27 of 44 (61.4%) negative patients (P< 0.001). No differences in the median loads of antigenomic HCV RNA between patients with an those without serum HCV RNA (4.5 × 104[range, 7.9 × 102to 1.0 × 106] versus 2.3 × 104[range, 4.0 × 102to 2.2 × 105]) were found. Alanine aminotransferase and gamma-glutamyl transpeptidase levels, liver necroinflammatory activity, and fibrosis did not differ between both groups. In conclusion, HCV RNA can be detected in the sera of patients with occult HCV infection after circulating viral particles are concentrated by ultracentrifugation.
VEGF receptor inhibition blocks liver cyst growth in pkd2(WS25/−) mice
Authors: Amura Claudia R. , Brodsky Kelley S. , Groff Rachel , Gattone Vincent H. , Voelkel Norbert F. , Doctor R. Brian
Published: May 2007

Proliferation of cyst-lining epithelial cells is an integral part of autosomal dominant polycystic kidney disease (ADPKD) cyst growth. Cytokines and growth factors within cyst fluids are positioned to induce cyst growth. Vascular endothelial growth factor (VEGF) is a pleiotropic growth factor present in ADPKD liver cyst fluids (human 1,128 ± 78, mouse 2,787 ± 136 pg/ml) and, to a lesser extent, in ADPKD renal cyst fluids (human 294 ± 41, mouse 191 ± 90 pg/ml). Western blotting showed that receptors for VEGF (VEGFR1 and VEGFR2) were present in both normal mouse bile ducts and pkd2(WS25/−) liver cyst epithelial cells. Treatment of pkd2(WS25/−) liver cyst epithelial cells with VEGF (50–50,000 pg/ml) or liver cyst fluid induced a proliferative response. The effect on proliferation of liver cyst fluid was inhibited by SU-5416, a potent VEGF receptor inhibitor. Treatment of pkd2(WS25/−) mice between 4 and 8 mo of age with SU-5416 markedly reduced the cyst volume density of the liver (vehicle 9.9 ± 4.3%, SU-5416 1.8 ± 0.7% of liver). SU-5416 treatment between 4 and 12 mo of age markedly protected against increases in liver weight [pkd2(+/+) 4.8 ± 0.2%, pkd2(WS25/−)-vehicle 10.8 ± 1.9%, pkd2(WS25/−)-SU-5416 4.8 ± 0.4% body wt]. The capacity of VEGF signaling to induce in vitro proliferation of pkd2(WS25/−) liver cyst epithelial cells and inhibition of in vivo VEGF signaling to retard liver cyst growth in pkd2(WS25/−) mice indicates that the VEGF signaling pathway is a potentially important therapeutic target in the treatment of ADPKD liver cyst disease.
The antiproliferative effects of agmatine correlate with the rate of cellular proliferation
Authors: Isome Masato , Lortie Mark J. , Murakami Yasuko , Parisi Eva , Matsufuji Senya , Satriano Joseph
Published: May 2007

Polyamines are small cationic molecules required for cellular proliferation. Agmatine is a biogenic amine unique in its capacity to arrest proliferation in cell lines by depleting intracellular polyamine levels. We previously demonstrated that agmatine enters mammalian cells via the polyamine transport system. As polyamine transport is positively correlated with the rate of cellular proliferation, the current study examines the antiproliferative effects of agmatine on cells with varying proliferative kinetics. Herein, we evaluate agmatine transport, intracellular accumulation, and its effects on antizyme expression and cellular proliferation in nontransformed cell lines and their transformed variants. H-ras- and Src-transformed murine NIH/3T3 cells (Ras/3T3 and Src/3T3, respectively) that were exposed to exogenous agmatine exhibit increased uptake and intracellular accumulation relative to the parental NIH/3T3 cell line. Similar increases were obtained for human primary foreskin fibroblasts relative to a human fibrosarcoma cell line, HT1080. Agmatine increases expression of antizyme, a protein that inhibits polyamine biosynthesis and transport. Ras/3T3 and Src/3T3 cells demonstrated augmented increases in antizyme protein expression relative to NIH/3T3 in response to agmatine. All transformed cell lines were significantly more sensitive to the antiproliferative effects of agmatine than nontransformed lines. These effects were attenuated in the presence of exogenous polyamines or inhibitors of polyamine transport. In conclusion, the antiproliferative effects of agmatine preferentially target transformed cell lines due to the increased agmatine uptake exhibited by cells with short cycling times.
Myosin II isoforms in smooth muscle: heterogeneity and function
Authors: Eddinger Thomas J. , Meer Daniel P.
Published: May 2007

Both smooth muscle (SM) and nonmuscle class II myosin molecules are expressed in SM tissues comprising hollow organ systems. Individual SM cells may express one or more of multiple myosin II isoforms that differ in myosin heavy chain (MHC) and myosin light chain (MLC) subunits. Although much has been learned, the expression profiles, organization within contractile filaments, localization within cells, and precise roles in various contractile functions of these different myosin molecules are still not well understood. However, data supporting unique physiological roles for certain isoforms continues to build. Isoform differences located in the S1 head region of the MHC can alter actin binding and rates of ATP hydrolysis. Differences located in the MHC tail can alter the formation, stability, and size of the myosin thick filament. In these distinct ways, both head and tail isoform differences can alter force generation and muscle shortening velocities. The MLCs that are associated with the lever arm of the S1 head can affect the flexibility and range of motion of this domain and possibly the motion of the S2 and motor domains. Phosphorylation of MLC20 has been associated with conformational changes in the S1 and/or S2 fragments regulating enzymatic activity of the entire myosin molecule. A challenge for the future will be delineation of the physiological significance of the heterogeneous expression of these isoforms in developmental, tissue-specific, and species-specific patterns and or the intra- and intercellular heterogeneity of myosin isoform expression in SM cells of a given organ.
Cloning and functional characterization of a folate transporter from the nematode Caenorhabditis elegans
Authors: Balamurugan Krishnaswamy , Ashokkumar Balasubramaniem , Moussaif Mustapha , Sze Ji Ying , Said Hamid M.
Published: May 2007

Two putative orthologs to the human reduced folate carrier (hRFC), folt-1 and folt-2, which share a 40 and 31% identity, respectively, with the hRFC sequence, have been identified in the Caenorhabditis elegans genome. Functional characterization of the open reading frame of the putative folt-1 and folt-2 showed folt-1 to be a specific folate transporter. Transport of folate by folt-1 expressed in a heterologous expression system showed an acidic pH dependence, saturability (apparent Km of 1.23 ± 0.18 μM), a similar degree of inhibition by reduced and substituted folate derivatives, sensitivity to the anti-inflammatory drug sulfasalazine (apparent K i of 0.13 mM), and inhibition by anion transport inhibitors, e.g., DIDS. Knocking down (silencing) or knocking out the folt-1 gene led to a significant inhibition of folate uptake by intact living C. elegans. We also cloned the 5′-regulatory region of the folt-1 gene and confirmed promoter activity of the construct in vivo in living C. elegans. With the use of the transcriptional fusion construct (i.e., folt-1::GFP), the expression pattern of folt-1 in different tissues of living animal was found to be highest in the pharynx and intestine. Furthermore, folt-1::GFP expression was developmentally and adaptively regulated in vivo. These studies demonstrate for the first time the existence of a specialized folate uptake system in C. elegans that has similar characteristics to the folate uptake process of the human intestine. Thus C. elegans provides a genetically tractable model that can be used to study integrative aspects of the folate uptake process in the context of the whole animal level.
Reduced urea flux across the blood-testis barrier and early maturation in the male reproductive system in UT-B-null mice
Authors: Guo Lirong , Zhao Dan , Song Yuanlin , Meng Yan , Zhao Huashan , Zhao Xuejian , Yang Baoxue
Published: May 2007

A urea-selective urine-concentrating defect was found in transgenic mice deficient in urea transporter (UT)-B. To determine the role of facilitated urea transport in extrarenal organs expressing UT-B, we studied the kinetics of [14C]urea distribution in UT-B-null mice versus wild-type mice. After renal blood flow was disrupted, [14C]urea distribution was selectively reduced in testis in UT-B-null mice. Under basal conditions, total testis urea content was 335.4 ± 43.8 μg in UT-B-null mice versus 196.3 ± 18.2 μg in wild-type mice ( P < 0.01). Testis weight in UT-B-null mice (6.6 ± 0.8 mg/g body wt) was significantly greater than in wild-type mice (4.2 ± 0.8 mg/g body wt). Elongated spermatids were observed earlier in UT-B-null mice compared with wild type mice on day 24 versus day 32, respectively. First breeding ages in UT-B knockout males (48 ± 3 days) were also significantly earlier than that in wild-type males (56 ± 2 days). In competing mating tests with wild-type males and UT-B-null males, all pups carried UT-B-targeted genes, which indicates that all pups were produced from breeding of UT-B-null males. Experiments of the expression of follicle-stimulating hormone receptor (FSHR) and androgen binding protein (ABP) indicated that the development of Sertoli cells was also earlier in UT-B-null mice than that in wild-type mice. These results suggest that UT-B plays an important role in eliminating urea produced by Sertoli cells and that UT-B deletion causes both urea accumulation in the testis and early maturation of the male reproductive system. The UT-B knockout mouse may be a useful experimental model to define the molecular mechanisms of early puberty.
Influence of endurance training on muscle [PCr] kinetics during high-intensity exercise
Authors: Jones Andrew M. , Wilkerson Daryl P. , Berger Nicolas J. , Fulford Jonathan
Published: May 2007

We hypothesized that a period of endurance training would result in a speeding of muscle phosphocreatine concentration ([PCr]) kinetics over the fundamental phase of the response and a reduction in the amplitude of the [PCr] slow component during high-intensity exercise. Six male subjects (age 26 ± 5 yr) completed 5 wk of single-legged knee-extension exercise training with the alternate leg serving as a control. Before and after the intervention period, the subjects completed incremental and high-intensity step exercise tests of 6-min duration with both legs separately inside the bore of a whole-body magnetic resonance spectrometer. The time-to-exhaustion during incremental exercise was not changed in the control leg [preintervention group (PRE): 19.4 ± 2.3 min vs. postintervention group (POST): 19.4 ± 1.9 min] but was significantly increased in the trained leg (PRE: 19.6 ± 1.6 min vs. POST: 22.0 ± 2.2 min; P < 0.05). During step exercise, there were no significant changes in the control leg, but end-exercise pH and [PCr] were higher after vs. before training. The time constant for the [PCr] kinetics over the fundamental exponential region of the response was not significantly altered in either the control leg (PRE: 40 ± 13 s vs. POST: 43 ± 10 s) or the trained leg (PRE: 38 ± 8 s vs. POST: 40 ± 12 s). However, the amplitude of the [PCr] slow component was significantly reduced in the trained leg (PRE: 15 ± 7 vs. POST: 7 ± 7% change in [PCr]; P < 0.05) with there being no change in the control leg (PRE: 13 ± 8 vs. POST: 12 ± 10% change in [PCr]). The attenuation of the [PCr] slow component might be mechanistically linked with enhanced exercise tolerance following endurance training.
Effect of exercise training on cardiac oxytocin and natriuretic peptide systems in ovariectomized rats
Authors: Gutkowska Jolanta , Paquette Amélie , Wang Donghao , Lavoie Jean-Marc , Jankowski Marek
Published: May 2007

Exercise training results in cardiovascular and metabolic adaptations that may be beneficial in menopausal women by reducing blood pressure, insulin resistance, and cholesterol level. The adaptation of the cardiac hormonal systems oxytocin (OT), natriuretic peptides (NPs), and nitric oxide synthase (NOS) in response to exercise training was investigated in intact and ovariectomized (OVX) rats. Ovariectomy significantly augmented body weight (BW), left ventricle (LV) mass, and intra-abdominal fat pad weight and decreased the expression of oxytocin receptor (OTR), atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and guanylyl cyclase-A (GC-A), in the right atrium (RA) and LV, indicating estrogenic control of these genes. These effects of ovariectomy were counteracted by 8-wk-long exercise training which decreased fat pad weight (33.4 ± 2.3 to 23.4 ± 3.1 g, n = 8, P < 0.05), plasma free fatty acids (0.124 ± 0.033 to 0.057 ± 0.010 mM, n = 8, P < 0.01), and plasma triacylglycerol (0.978 ± 0.174 to 0.588 ± 0.115 mM, n = 8, P < 0.05). Chronic exercise tended to decrease BW and stimulated ANP (4- to 5-fold) and OTR gene expression in the LV and RA and BNP and inducible NOS (iNOS) mRNA in the LV. In sham-operated rats, exercise augmented ANP expression in the RA, downregulated GC-A mRNA in the LV and RA, but increased its expression threefold in the RA of OVX animals. Endothelial NOS and iNOS expression was enhanced in the left atrium of sham-operated rats. Altogether, these data indicate that in OVX animals, chronic exercise significantly enhances cardiac OT, NPs, and NOS, thus implicating all three hormonal systems in the beneficial effects of exercise training.
Learned flavor preferences induced by intragastric administration of rewarding nutrients: role of capsaicin-sensitive vagal afferent fibers
Authors: Zafra Maria A. , Molina Filomena , Puerto Amadeo
Published: May 2007

Learned flavor preferences can be established after intragastric nutrient administration by two different behavioral procedures, concurrent and sequential. In a concurrent procedure, two flavored stimuli are offered separately but at the same time on a daily basis: one stimulus is paired with the simultaneous intragastric administration of partially digested food and the other with physiological saline. In sequential learning, the two stimuli are presented during alternate sessions. Neural mechanisms underlying these learning modalities have yet to be fully elucidated. The aim of this study was to examine the role of vagal afferent fibers in the visceral processing of rewarding nutrients during concurrent ( experiment 1) and sequential ( experiment 2) flavor preference learning in Wistar rats. For this purpose, capsaicin, a neurotoxin that destroys slightly myelinated or unmyelinated sensory axons, was applied to the subdiaphragmatic region of the esophagus to selectively damage most of the vagal afferent pathways that originate in the gastrointestinal system. Results showed that capsaicin [1 mg of capsaicin dissolved in 1 ml of vehicle (10% Tween 80 in oil)] blocked acquisition of concurrent but not sequential flavor preference learning. These results are interpreted in terms of a dual neurobiological system involved in processing the rewarding effects of intragastrically administered nutrients. The vagus nerve, specifically capsaicin-sensitive vagal afferent fibers, would only be essential in concurrent flavor preference learning, which requires rapid processing of visceral information.
Renal angiotensin II concentration and interstitial infiltration of immune cells are correlated with blood pressure levels in salt-sensitive hypertension
Authors: Franco Martha , Martínez Flavio , Quiroz Yasmir , Galicia Othir , Bautista Rocio , Johnson Richard J. , Rodríguez-Iturbe Bernardo
Published: May 2007

Renal immune cell infiltration and cells expressing angiotensin II (AII) in tubulointerstitial areas of the kidney are features of experimental models of salt-sensitive hypertension (SSHTN). A high-salt intake tends to suppress circulating AII levels, but intrarenal concentrations of AII have not been investigated in SSHTN. This study explored the relationship between these features to gain insight into the pathophysiology of SSHTN. Plasma angiotensin II (AII) and renal interstitial AII (microdialysis technique) and the infiltration of macrophages, lymphocytes, and AII-positive cells were determined in SSHTN induced by 5 wk of a high-salt diet (HSD) after short-term infusion of AII in rats with ( n = 10) and without ( n = 11) treatment with mycophenolate mofetil (MMF) and in control rats fed a high- ( n = 7) and normal ( n = 11) salt diet. As in previous studies, MMF did not affect AII-associated hypertension but reduced the interstitial inflammation and the SSHTN in the post-AII-period. During the HSD period, the AII group untreated with MMF had mean ± SD) low plasma (2.4 ± 1.4 pg/ml) and high interstitial AII concentration (1,310 ± 208 pg/ml); MMF treatment resulted in a significantly lower interstitial AII (454 ± 128 pg/ml). Renal AII concentration and the number of tubulointerstitial AII-positive cells were correlated. Blood pressure correlated positively with interstitial AII and negatively with plasma AII, thus giving compelling evidence of the paramount role of the AII within the kidney in the AII-induced model of salt-driven hypertension.
Vascular development in early ovine gestation: carotid smooth muscle function, phenotype, and biochemical markers
Authors: Hutanu Catalina , Cox Blair E. , DeSpain Kevin , Liu Xiao-Tie , Rosenfeld Charles R.
Published: May 2007

Vascular smooth muscle (VSM) maturation is developmentally regulated and differs between vascular beds. The maturation and contribution of VSM function to tissue blood flow and blood pressure regulation during early gestation are unknown. The carotid artery (CA) contributes to fetal cerebral blood flow regulation and well being. We studied CA VSM contractility, protein contents, and phenotype beginning in the midthird of ovine development. CAs were collected from early (88–101 day of gestation) and late (138–150 day; term = day 150) fetal ( n = 14), newborn (6–8 day old; n = 7), and adult ( n = 5) sheep to measure forces in endothelium-denuded rings with KCl, phenylephrine, and ANG II; changes in cellular proteins, including total and soluble protein, actin and myosin, myosin heavy chain isoforms (MHC), filamin, and proliferating cell nuclear antigen; and vascular remodeling. KCl and phenylephrine elicited age- and dose-dependent contraction responses ( P < 0.001) at all ages except early fetal, which were unresponsive. In contrast, ANG II elicited dose responses only in adults, with contractility increasing greater than fivefold vs. that shown in fetal or neonatal animals ( P < 0.001). Increased contractility paralleled age-dependent increases ( P < 0.01) in soluble protein, actin and myosin, filamin, adult smooth muscle MHC-2 (SM2) and medial wall thickness and reciprocal decreases ( P < 0.001) in nonmuscle MHC-B, proliferating cell nuclear antigen and medial cellular density. VSM nonreceptor- and receptor-mediated contractions are absent or markedly attenuated in midgestation and increase age dependently, paralleling the transition from synthetic to contractile VSM phenotype and, in the case of ANG II, paralleling the switch to the AT1receptor. The mechanisms regulating VSM maturation and thus blood pressure and tissue perfusion in early development remain to be determined.
Rat carotid body chemosensory discharge and glomus cell HIF-1α expression in vitro: regulation by a common oxygen sensor
Authors: Roy Arijit , Baby Santhosh M. , Wilson David F. , Lahiri Sukhamay
Published: May 2007

Addition of Pco (∼350 Torr) to a normoxic medium (Po2 of ∼130 Torr) was used to investigate the relationship between carotid body (CB) sensory discharge and expression of hypoxia-inducible factor 1α (HIF-1α) in glomus cells. Afferent electrical activity measured for in vitro -perfused rat CB increased rapidly (1–2 s) with addition of high CO (Pco of ∼350 Torr; Po2 of ∼130 Torr), and this increase was fully reversed by white light. At submaximal light intensities, the extent of reversal was much greater for monochromatic light at 430 and 590 nm than for light at 450, 550, and 610 nm. This wavelength dependence is consistent with the action spectrum of the CO compound of mitochondrial cytochrome a3. Interestingly, when isolated glomus cells cultured for 45 min in the presence of high CO (Pco of ∼350 Torr; Po2 of ∼130 Torr) in the dark, the levels of HIF-1α, which turn over slowly (many minutes), increased. This increase was not observed if the cells were illuminated with white light during the incubation. Monochromatic light at 430- and 590-nm light was much more effective than that at 450, 550, and 610 nm in blocking the CO-induced increase in HIF-1α, as was the case for chemoreceptor discharge. Although the changes in HIF-1α take minutes and those for CB neural activity occur in 1–2 s, the similar responses to CO and light suggest that the oxygen sensor is the same (mitochondrial cytochrome a3).
Underexpression of the Na+-dependent neutral amino acid transporter ASCT2 in the spontaneously hypertensive rat kidney
Authors: Pinho Maria João , Pinto Vanda , Serrão Maria Paula , Jose Pedro A. , Soares-da-Silva Patrício
Published: May 2007

This study examined the inward transport of l-[14C]alanine, an ASCT2 preferential substrate, in monolayers of immortalized renal proximal tubular epithelial (PTE) cells from Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats. The expression of ASCT2 in WKY and SHR PTE cells and kidney cortices from WKY and SHR was also evaluated. l-[14C]alanine uptake was highly dependent on extracellular Na+. Replacement of NaCl by LiCl or choline chloride abolished transport activity in SHR and WKY PTE cells. In the presence of the system L inhibitor BCH, Na+-dependent l-alanine uptake in WKY and SHR PTE cells was inhibited by alanine, serine, and cysteine, which is consistent with amino acid transport through ASCT2. The saturable component of Na+-dependent l-alanine transport under Vmaxconditions in SHR PTE cells was one-half of that in WKY PTE cells, with similar Kmvalues. Differences in magnitude of Na+-dependent l-alanine uptake through ASCT2 between WKY and SHR PTE cells correlated positively with differences in ASCT2 protein expression, this being more abundant in WKY PTE cells. Abundance of ASCT2 transcript and protein in kidney cortices of SHR rats was also lower than that in normotensive WKY rats. In conclusion, immortalized SHR and WKY PTE cells take up l-alanine mainly through a high-affinity Na+-dependent amino acid transporter, with functional features of ASCT2 transport. The activity and expression of the ASCT2 transporter were considerably lower in the SHR cells.
Altered expression of epithelial sodium channel in rats with bilateral or unilateral ureteral obstruction
Authors: Li Chunling , Wang Weidong , Norregaard Rikke , Knepper Mark A. , Nielsen Søren , Frøkiær Jørgen
Published: May 2007

The roles of epithelial sodium channel (ENaC) subunits (α, β, and γ) in the impaired renal reabsorption of sodium and water were examined in rat models with bilateral (BUO) or unilateral ureteral obstruction (UUO) for 24 h or with BUO followed by release of obstruction and 3 days of observation (BUO-3dR). In BUO rats, plasma osmolality was increased dramatically, whereas plasma sodium concentration was decreased. Immunoblotting revealed a significantly decreased expression of α-ENaC (57 ± 7%), β-ENaC (19 ± 5%), and γ-ENaC (51 ± 10%) as well as 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) in the cortex and outer medulla (C+OM) compared with sham-operated controls. This was confirmed by immunohistochemistry. BUO-3dR was associated with polyuria and impaired renal sodium handling. The protein abundance and the apical labeling of α-ENaC were significantly increased, whereas β- and γ-ENaC as well as 11β-HSD2 expression remained decreased. In UUO rats, expression of α- and β-ENaC and 11β-HSD2 decreased in the C+OM in the obstructed kidney. In contrast, the abundance and the apical labeling of α-ENaC in the nonobstructed kidneys were markedly increased, suggesting compensatory upregulation in this kidney. In conclusion, α-, β-, and γ-ENaC expression levels are downregulated in the obstructed kidney. The expression and apical labeling of α-ENaC were increased in BUO-3dR rats and in the nonobstructed kidneys from UUO rats. These results suggest that altered expression of α-, β-, and γ-ENaC may contribute to impaired renal sodium and water handling in response to ureteral obstruction.
Most Superficial Sublamina of Rat Superior Colliculus: Neuronal Response Properties and Correlates With Perceptual Figure–Ground Segregation
Authors: Girman S. V. , Lund R. D.
Published: May 2007

The uppermost layer (stratum griseum superficiale, SGS) of the superior colliculus (SC) provides an important gateway from the retina to the visual extrastriate and visuomotor systems. The majority of attention has been given to the role of this “visual” SC in saccade generation and target selection and it is generally considered to be less important in visual perception. We have found, however, that in the rat SGS1, the most superficial division of the SGS, the neurons perform very sophisticated analysis of visual information. First, in studying their responses with a variety of flashing stimuli we found that the neurons respond not to brightness changes per se, but to the appearance and/or disappearance of visual shapes in their receptive fields (RFs). Contrary to conventional RFs of neurons at the early stages of visual processing, the RFs in SGS1 cannot be described in terms of fixed spatial distribution of excitatory and inhibitory inputs. Second, SGS1 neurons showed robust orientation tuning to drifting gratings and orientation-specific modulation of the center response from surround. These are features previously seen only in visual cortical neurons and are considered to be involved in “contour” perception and figure–ground segregation. Third, responses of SGS1 neurons showed complex dynamics; typically the response tuning became progressively sharpened with repetitive grating periods. We conclude that SGS1 neurons are involved in considerably more complex analysis of retinal input than was previously thought. SGS1 may participate in early stages of figure–ground segregation and have a role in low-resolution nonconscious vision as encountered after visual decortication.
Hydrogen Sulfide Induces Direct Radical-Associated DNA Damage
Authors: Attene-Ramos Matias S. , Wagner Elizabeth D. , Gaskins H. Rex , Plewa Michael J.
Published: May 2007

Hydrogen sulfide (H2S) is produced by indigenous sulfate-reducing bacteria in the large intestine and represents an environmental insult to the colonic epithelium. Clinical studies have linked the presence of either sulfate-reducing bacteria or H2S in the colon with chronic disorders such as ulcerative colitis and colorectal cancer, although at this point, the evidence is circumstantial and underlying mechanisms remain undefined. We showed previously that sulfide at concentrations similar to those found in the human colon induced genomic DNA damage in mammalian cells. The present study addressed the nature of the DNA damage by determining if sulfide is directly genotoxic or if genotoxicity requires cellular metabolism. We also questioned if sulfide genotoxicity is mediated by free radicals and if DNA base oxidation is involved. Naked nuclei from untreated Chinese hamster ovary cells were treated with sulfide; DNA damage was induced by concentrations as low as 1 μmol/L. This damage was effectively quenched by cotreatment with butylhydroxyanisole. Furthermore, sulfide treatment increased the number of oxidized bases recognized by formamidopyrimidine [fapy]-DNA glycosylase. These results confirm the genotoxicity of sulfide and strongly implicate that this genotoxicity is mediated by free radicals. These observations highlight the possible role of sulfide as an environmental insult that, given a predisposing genetic background, may lead to genomic instability or the cumulative mutations characteristic of colorectal cancer. (Mol Cancer Res 2007;5(5):455–9)
Gathered from Coincidence: Reflections on Art in a Time of Global Warming
Authors: Gessert George
Published: May 2007

How will global warming affect art? The author proposes that the effects will be continuous with other human-caused threats to civilization such as nuclear weapons. Such threats have already contributed to devaluation of the human figure. In many different times and places, the primary focus of art, with the notable exception of Western art, has been on nonhuman imagery. Global warming will give this new significance. Questions of permanence and impermanence in art are also likely to become more relevant.
The Non-Realistic Nature of Photography: Further Reasons Why Turner Was Wrong
Authors: Latto Richard , Harper Bernard
Published: May 2007

The authors discuss the limitations of photography in producing representations that lead to the accurate perception of shapes. In particular, they consider two situations in which the photographic representation, although an accurate reproduction of the geometry of the two-dimensional image in the eye, does not capture the way human vision changes this geometry to produce a three-dimensionally accurate perception. When looking at a photograph, the viewer's uncertainty of the camera-to-subject distance and the fact that, unnaturally, a photograph presents almost exactly the same view of an object to the two eyes result in substantially distorted perceptions. These most commonly result in a perceived flattening and fattening of the 3D shape of the object being photographed.
Alcohol's Effects on Goal-Related Appraisals and Communicative Behaviors
Authors: Monahan Jennifer L. , Samp Jennifer A.
Published: May 2007

Guided by research demonstrating that intoxication impairs cognitive processing, this study examined the effects of drinking on goal-related appraisals and communication behavior during cooperative interactions. In it, 42 male teams played four rounds of a cooperative game whereby one person produced clues and the other guessed the category the clues described. One partner was sober and the other was randomly assigned to drinking condition (sober or breath alcohol count of .08 g/dl). Analyses compared the appraisals and behaviors of the participant randomly assigned to drinking condition. Intoxicated participants felt less anxious and judged games as less challenging yet did not feel they had more control compared to their sober counterparts. Behaviorally, intoxicated participants exhibited more persistence yet were less flexible in goal pursuit than were sober participants. Ultimately, intoxicated—sober dyads had more success than did sober—sober dyads. Implications for message production under the influence of alcohol are discussed.
Estimation of Energy Expenditure in Healthy Adults From the YMCA Submaximal Cycle Ergometer Test
Authors: Garatachea Nuria , Cavalcanti Euclides , García-López David , González-Gallego Javier , de Paz Jose A.
Published: May 2007

There is a lack of simple field methods for obtaining accurate and reliable information on energy expenditure (EE) during physical activity. This study aims to investigate the validity of the YMCA Submaximal Cycle Ergometer Test to predict EE at submaximal intensities. Twenty-eight participants of each sex volunteered for the study and performed a maximal oxygen uptake (V O2max) incremental test, a submaximal exercise test (three 5-min loads at 40%, 55%, and 70% V O2max) and the YMCA Test that provides an extrapolation based on heart rate (HR) to predict V O2 (YMCA V O2—HR). Results indicate that predicted V O2max from the YMCA Test was significantly different from the gold standard. However, predicted V O2 at different relative submaximal intensities did not significantly differ from directly measured V O2. In conclusion, the HR method using the YMCA V O2—HR relationship appears to be effective in predicting EE at submaximal intensities but not at maximum efforts.
Reconceptualizing Research on Undergraduate Alcohol Use
Authors: Osborn Cynthia J. , Thombs Dennis L. , Olds R. Scott
Published: May 2007

Community-based participatory research (CBPR) is presented as an unrecognized and urgently needed approach for addressing the persistent public health concern of college student drinking in the United States. A major contention of this article is that the lack of progress in reducing alcohol-related harm among college students during the past several decades has been the research community's failure to effectively engage and collaborate with undergraduates on shared concerns. The challenges of addressing college student drinking are reviewed, distinctive features of CBPR are described, and suggestions are provided for adopting CBPR as a more viable approach than those offered by traditional campus strategies.
Task Analysis Revisited
Authors: Fidler James R.
Published: May 2007

A random sample of 500 phlebotomy technicians certified by a national organization was queried regarding perceptions of importance of 53 specific practice-related tasks representative of various departmental areas. The sample was surveyed via a mail questionnaire. Role centrality was assessed by considering mean importance ratings and by applying the Rasch measurement model to assigned importance ratings. Approximately 36% of the questionnaires received by respondents were returned. The results revealed which tasks were fundamental to the phlebotomy technician scope of practice. To assess longitudinal change in core duties, task saliency was considered with respect to similar data collected a decade earlier. Task importance may be considered by agencies that educate, credential, or employ phlebotomy technicians in providing current job function descriptions. The longitudinal methodology employed may be applicable to other job roles for which the assessment of change is of interest.
Nonresponse Bias in a Mail Survey of Physicians
Authors: McFarlane Emily , Olmsted Murrey G. , Murphy Joe , Hill Craig A.
Published: May 2007

With the increased pressure on survey researchers to achieve high response rates, it is critical to explore issues related to nonresponse. In this study, the authors examined the effects of nonresponse bias in a mail survey of physicians ( N = 3,400). Because slightly more than one half of the sample did not respond to the survey, there was potential for bias if nonresponders differed significantly from responders with respect to key demographic and practice variables. They analyzed response status and timing of response with respect to five variables: gender, region, specialty, urbanicity, and survey length. The potential consequences of nonresponse bias on the survey estimates were then analyzed. Men were more likely to respond, as were physicians receiving a shorter questionnaire. Repeated follow-up attempts reduced gender response bias because male physicians were more likely to be early responders. Overall, higher response rates were not associated with lower response bias.
Mail Versus Internet Surveys
Authors: Lusk Christine , Delclos George L. , Burau Keith , Drawhorn Derek D. , Aday Lu Ann
Published: May 2007

The authors evaluated determinants of response to Internet-based surveys in a sample (n = 5600) of Texas healthcare professionals. Participants were given the option of responding by mail or over the Web (response, 66%). Internet respondents were younger ( p < .001), had worked fewer years in healthcare ( p < .001), and were more likely to be male ( p < .001) and to work in a hospital ( p = .007). Missing questionnaire items were significantly higher among Web responders with regard to age, sex, race, body mass index, and smoking ( p < .001). In the final multivariate logistic regression, only male gender (odds ratio [OR] = 2.09, 95% CI = 1.56-2.80) and younger age remained significantly associated with response over the Internet. Age quartile and responding electronically were inversely associated. Taken together with a priori knowledge of the demographic and professional profile of a study population, these findings can be useful in planning and implementation of surveys among healthcare workers.
Work–Family Conflict, Children, and Hour Mismatches in Australia
Authors: Reynolds Jeremy , Aletraris Lydia
Published: May 2007

This article helps integrate research on work hours and work—family issues by examining how work—family conflict is related to the desire for more and fewer hours of work. Using the first wave of the Household Income and Labor Dynamics in Australia survey, we find that work-to-family conflict is associated with a desire for fewer hours of work. Family-to-work conflict, however, is only weakly associated with desired work hour changes, and we find some evidence that it makes women want to increase the number of hours they work. We also find evidence of moderating effects: Work-to-family conflict is more likely to make women want fewer hours when they have preschool children. We conclude that many working parents see work hour reductions as a way to cope with work—family conflict but that people prefer different coping strategies depending on their gender and family situation.
Religious Influences on Work–Family Trade-Offs
Authors: Ammons Samantha K. , Edgell Penny
Published: May 2007

Despite a large body of research on the influences of religion on family life and gender ideology, few studies examined how religion affects work—family strategies. One set of strategies involves making employment or family trade-offs—strategies of devoting time or attention to either work or family in a situation in which one cannot devote the preferred amount of time and attention to both, strategies that may be experienced as making sacrifices, hard choices, or accommodations. Using 1996 General Social Survey data, the authors analyze how religion affects employment and family trade-offs. They develop hypotheses about the institutional effects of religious involvement and effects of involvement in a conservative religious subculture . They find that religious involvement and religious subculture shape trade-offs in gender-specific ways, and that religion affects more of men's trade-offs. They conclude by calling for further research on the social sources of cultural frameworks that shape men's and women's work—family strategies.
Football Academies and the Migration of African Football Labor to Europe
Authors: Darby Paul , Akindes Gerard , Kirwin Matthew
Published: May 2007

This article analyzes one of the key features of the increased trading in African football labor since the 1990s, the establishment of football “academies” in Africa. The article begins by setting out a broad explanatory framework that articulates the transit of African footballers to Europe and the role of football academies in this process as a form of neocolonial exploitation and impoverishment of the developing world by the developed world. A brief account of the history, geography, economics, and consequences of African football talent migration to Europe follows. The main focus of the article is the construction of a typology of football academies in Africa and an analysis of their role in the export of African football labor. The article concludes by analyzing the key challenges that the growth of football academies has posed for the African game and outlines ways that these challenges might be addressed.
Evaluating Technical and Technological Innovations in Sport
Authors: Sheridan Heather
Published: May 2007

This article explores the method of “reflective equilibrium” as a possible decision-making method for the rational evaluation of technical and technological innovations in sporting practices. I use the recent change to the way male tennis players are seeded at the Wimbledon championships to illustrate that although fair play comprises an important part of any evaluation, it only takes us so far. I discuss critically the objection that “wide reflective equilibrium” disregards the diversity and the moral importance of the different cultures in which people live. I argue that although “wide reflective equilibrium” is a praiseworthy procedure for evaluating technical and technological innovations in sporting practices, it is too “thin” a method because it disregards the diversity and the moral importance of the different cultures in which people live in general and sporting practices more specifically. I offer instead the outline of an alternative decision-making method that includes a more embedded conception of the good.