bluuebunny/crossref_metadata_2025 huggingface dataset:
Bringing Identity Theory into Environmental Sociology
Authors: Stets Jan E. , Biga Chris F.
Published: November 2003

In an effort to explain pro-environmental behavior, environmental sociologists often study environmental attitudes. While much of this work is atheoretical, the focus on attitudes suggests that researchers are implicitly drawing upon attitude theory in psychology. The present research brings sociological theory to environmental sociology by drawing on identity theory to understand environmentally responsive behavior. We develop an environment identity model of environmental behavior that includes not only the meanings of the environment identity, but also the prominence and salience of the environment identity and commitment to the environment identity. We examine the identity process as it relates to behavior, though not to the exclusion of examining the effects of environmental attitudes. The findings reveal that individual agency is important in influencing environmentally responsive behavior, but this agency is largely through identity processes, rather than attitude processes. This provides an important theoretical and empirical advance over earlier work in environmental sociology.
A Closer Look at Gender and Strategy Use in L2 Reading
Authors: Phakiti Aek
Published: November 2003

This study examines gender differences in cognitive and metacognitive strategy use in the context of an English as a foreign language reading comprehension test. Three hundred eighty‐four Thai university students took a multiple‐choice reading comprehension test, then completed a questionnaire on their strategy use. Gender differences were analyzed using multivariate analysis of variance. Males and females did not differ in their reading comprehension performance and their use of cognitive strategies. Unexpectedly, males reported significantly higher use of metacognitive strategies than females. Within the same achievement groups (highly successful, moderately successful, and unsuccessful), however, there were no gender differences in either reading performance or use of cognitive and metacognitive strategies. The article discusses the implications for future gender‐based research.
Supernatural Support Groups: Who Are the UFO Abductees and Ritual‐Abuse Survivors?
Authors: Bader Christopher D.
Published: November 2003

In the 1980s two different groups emerged that exhibited a strikingly similar combination of the quasi‐religious and psychotherapeutic—UFO abductees and ritual‐abuse survivors. Both movements focused on healing members from victimization they had experienced at the hands of beings of often supernatural power. Further, both movements attempt to use techniques developed in psychotherapeutic circles, such as hypnosis, art therapy, and role playing, to recover “repressed” memories at the hands of these abusers. This article presents the results of surveys of 55 UFO abductees and 51 ritual‐abuse survivors. Both UFO abductees and ritual‐abuse survivors are compared to the general population in terms of their gender, age, race, marital status, education, and occupation. It is determined that the demographics of these two fledgling movements closely mirror those of other NRMs.
Apolipoprotein E and β‐amyloid (1–42) regulation of glycogen synthase kinase‐3β
Authors: Cedazo‐Mínguez A. , Popescu B. O. , Blanco‐Millán J. M. , Akterin S. , Pei J‐J. , Winblad B. , Cowburn R. F.
Published: November 2003

Glycogen synthase kinase‐3β (GSK‐3β) is implicated in regulating apoptosis and tau protein hyperphosphorylation in Alzheimer's disease (AD). We investigated the effects of two key AD molecules, namely apoE (E3 and E4 isoforms) and β‐amyloid (Aβ) 1–42 on GSK‐3β and its major upstream regulators, intracellular calcium and protein kinases C and B (PKC and PKB) in human SH‐SY5Y neuroblastoma cells. ApoE3 induced a mild, transient, Ca2+‐independent and early activation of GSK‐3β. ApoE4 effects were biphasic, with an early strong GSK‐3β activation that was partially dependent on extracellular Ca2+, followed by a GSK‐3β inactivation. ApoE4 also activated PKC‐α and PKB possibly giving the subsequent GSK‐3β inhibition. Aβ(1–42) effects were also biphasic with a strong activation dependent partially on extracellular Ca2+ followed by an inactivation. Aβ(1–42) induced an early and potent activation of PKC‐α and a late decrease of PKB activity. ApoE4 and Aβ(1–42) were more toxic than apoE3 as shown by MTT reduction assays and generation of activated caspase‐3. ApoE4 and Aβ(1–42)‐induced early activation of GSK‐3β could lead to apoptosis and tau hyperphosphorylation. A late inhibition of GSK‐3β through activation of upstream kinases likely compensates the effects of apoE4 and Aβ(1–42) on GSK‐3β, the unbalanced regulation of which may contribute to AD pathology.
Inhibition of non‐vesicular glutamate release by group III metabotropic glutamate receptors in the nucleus accumbens
Authors: Xi Zheng‐Xiong , Shen Hui , Baker David A. , Kalivas Peter W.
Published: November 2003

Previous in vitro studies have shown that group III metabotropic glutamate receptors (mGluRs) regulate synaptic glutamate release. The present study used microdialysis to characterize this regulation in vivo in rat nucleus accumbens. Reverse dialysis of the group III mGluR agonist l‐(+)‐2‐amino‐4‐phosphonobutyric acid (L‐AP4) decreased, whereas the antagonist (R,S)‐α‐methylserine‐O‐phosphate (MSOP) increased the extracellular level of glutamate. The decrease by L‐AP4 or the increase by MSOP was antagonized by co‐administration of MSOP or L‐AP4, respectively. Activation of mGluR4a by (1S,3R,4S)‐1‐aminocyclopentane‐1,2,4‐tricarboxylic acid or mGluR6 by 2‐amino‐4‐(3‐hydroxy‐5‐methylisoxazol‐4‐yl)butyric acid had no effect on extracellular glutamate. (R,S)‐4‐Phosphonophenylglycine (PPG), another group III agonist with high affinity for mGluR4/6/8, reduced extracellular glutamate only at high concentrations capable of binding to mGluR7. The increase in extracellular glutamate by MSOP was tetrodotoxin‐independent, and resistant to both the L‐type and N‐type Ca2+ channel blockers. L‐AP4 failed to block 30 mm K+‐induced vesicular glutamate release. Blockade of glutamate uptake by d,l‐threo‐β‐benzyloxyaspartate caused a Ca2+‐independent elevation in extracellular glutamate that was reversed by L‐AP4. Finally, (S)‐4‐carboxyphenylglycine, an inhibitor of cystine‐glutamate antiporters, attenuated the L‐AP4‐induced reduction in extracellular glutamate. Together, these data indicate that group III mGluRs regulate in vivo extracellular glutamate in the nucleus accumbens by inhibiting non‐vesicular glutamate release.
Gene expression of α‐endosulfine in the rat brain: correlative changes with aging, learning and stress
Authors: Dou Jingtao , Cui Changhai , Dufour Franck , Alkon Daniel L. , Zhao Wei‐Qin
Published: November 2003

Endosulfine (EDSF) belongs to a highly conserved cAMP‐regulated phosphoprotein (ARPP) family and was first isolated from ovine brain as a possible endogenous ligand for sulfonylurea receptors. To explore its involvement in brain functions, we investigated regional distribution of α‐EDSF gene expression in the rat brain, and its regulation under physiological and pathological conditions. The majority of α‐EDSF gene was expressed in the pyramidal neurons, which represent the principal excitatory neurons in various brain regions. Down‐regulation of α‐EDSF mRNA was detected in the rat hippocampus during long‐term memory consolidation following a spatial learning experience, whereas swimming‐related stress caused persistent up‐regulation of α‐EDSF gene expression in several brain regions. These changes, however, were absent from brains of diabetic rats that were subjected to the same behavioral treatments. Intracerebroventricular injection of streptozocin with a toxic dose induced severe learning deficits and brain structure alteration accompanied by a massive increase of α‐EDSF mRNA in the somatosensory cortex. These results suggest that α‐EDSF gene expression is differentially regulated by distinct brain processes involving excitatory neuronal activities.
Dinucleotide microsatellite markers from Anopheles funestus
Authors: Schemerhorn B. J. , Greeman S. , Banks M. , Vulule J. , Sagnon N.‐F. , Costantini C. , Besansky N. J.
Published: November 2003

A total of 39 dinucleotide microsatellite‐containing clones were sequenced from a principal African malaria vector, Anopheles funestus. Primers designed to amplify 20 loci were used to genotype A. funestus mosquitoes from Burkina Faso and Kenya. Of nine polymorphic loci that amplified reliably and could be scored unambiguously, the overall within‐sample gene diversity was similar between locales, 0.77 and 0.78, with an allelic richness per locus of five to 11. Both the high level of polymorphism and absence of significant heterozygote deficiency at any locus favour these markers for studies of population structure that are vital to controlling this medically important species.
PCR primers for microsatellite loci in the tiger rattlesnake (Crotalus tigris, Viperidae)
Authors: Goldberg Caren S. , Edwards Taylor , Kaplan Matthew E. , Goode Matt
Published: November 2003

The tiger rattlesnake (Crotalus tigris) is found only in the Sonoran Desert of North America, where it inhabits rocky foothills that are increasingly being affected by urban encroachment. In order to continue a long‐term study of the demography and movements of tiger rattlesnakes around Tucson, Arizona, we identified six novel polymorphic microsatellite loci for this species. All loci exhibited high variability (five to 41 alleles). These markers are useful for studies of paternity, population structure, and assessing appropriate destinations for translocated animals.
Isolation of microsatellite markers from the drepanosiphid aphid Tuberculatus quercicola (Homoptera, Aphididae)
Authors: Yao Izumi , Akimoto Shin‐ICHI , Hasegawa Eisuke
Published: November 2003

We isolated five polymorphic microsatellite loci from the drepanosiphid aphid Tuberculatus quercicola (Matsumura) that is associated with the Daimyo oak, Quercus dentata Thunberg, using the magnetic particles method. The isolated loci were polymorphic, with four to 16 alleles in 40 aphids. Expected heterozygosities ranged from 0.4 to 0.82. These loci can be used to quantify seasonal changes in clonal diversity in the metapopulation and the extent of clonal mixing in the colonies.
Microsatellite markers from the Julia Creek dunnart, Sminthopsis douglasi (Marsupialia: Dasyuridae)
Authors: Spencer P. B. S. , Fletcher T. P. , Woolley P. A.
Published: November 2003

The Julia Creek dunnart (Sminthopsis douglasi) was not recognized as a distinct species until 1979. The description was based on three specimens held in museum collections and, prior to 1991, it was thought that the species might have become extinct. A few small populations are now known to exist but the species is currently listed as endangered. Here we characterize seven dinucleotide microsatellite loci with between two and nine alleles per locus and expected heterozygosities ranging from 0.53 to 0.91. These markers provide an additional approach to the study of the ecology and conservation status of the Julia Creek dunnart.
Isolation and characterization of polymorphic microsatellite loci in the endangered Portuguese freshwater fish Squalius aradensis (Cyprinidae)
Authors: Mesquita N. , Cunha C. , Hänfling B. , Carvalho G. R. , Zé‐Zé L. , Tenreiro R. , Coelho M. M.
Published: November 2003

Here we describe the isolation and characterization of six polymorphic microsatellite loci for Squalius aradensis. The number of observed alleles per locus ranged from three to 16 and the observed heterozygosity from 0.22 to 0.95. These primers will be useful in determining the population structure of S. aradensis and for conservation genetics of this endangered and endemic species. Furthermore, successful cross‐species amplification in S. alburnoides and Chondrostoma lusitanicum suggests that a wider amplification of these markers is possible.
Evolutionary conservation and versatility of a new set of primers for amplifying the ribosomal internal transcribed spacer regions in insects and other invertebrates
Authors: Ji Ya‐Jie , Zhang De‐Xing , He Li‐Jun
Published: November 2003

The evolutionary conservation and versatility of a new set of nuclear primers for the amplification of the ribosomal internal transcribed spacer regions in insects and other invertebrates have been studied. These primers, conserved across Insecta and other invertebrates, are based on a comprehensive taxonomic survey of the current DNA sequence databases. Their versatility was demonstrated by extensive polymerase chain reaction assays in 16 species from two arachnid orders, eight insect orders, three invertebrate and vertebrate chordate orders and by direct sequencing of the amplified products. The availability of these primers to the insect research community should facilitate the use of internal transcribed spacer regions in intraspecific studies as well as phylogenetic analysis of closely related taxa.
Microsatellite markers in western hemlock [Tsuga heterophylla (Raf.) Sarg]
Authors: Wellman Hugh , Pritchard Emily , Benowicz Andy , Ally Dilara , Ritland Carol
Published: November 2003

Fifteen microsatellite markers have been isolated from western hemlock [Tsuga heterophylla (Raf.) Sarg] genomic DNA and six of these markers were optimized for use in mountain hemlock [Tsuga mertensiana (Bong) Carr.]. The mean expected heterozygosity (HE) was 0.88 and 0.89 for western hemlock and mountain hemlock, respectively. Allelic diversity was high for both hemlock species, ranging from 7 to 15 alleles per locus for western hemlock and 5–30 alleles per locus for mountain hemlock. The allelic variation identified in this project will allow monitoring of changes in genetic variation as a result of selection pressure in breeding programs.
Isolation of 39 polymorphic microsatellite loci and the development of a fluorescently labelled marker set for the Eurasian badger (Meles meles) (Carnivora: Mustelidae)
Authors: Carpenter Petra J. , Dawson Deborah A. , Greig Carolyn , Parham Andrew , Cheeseman Chris L. , Burke Terry
Published: November 2003

We have isolated 78 microsatellite loci from the Eurasian badger (Meles meles). Of the 52 loci characterized, 39 were found to be polymorphic. A fluorescently labelled primer set was developed to enable individual‐specific 17‐locus genotypes to be obtained efficiently.
Polymorphic tetranucleotide microsatellite DNA loci from the southern dusky salamander (Desmognathus auriculatus)
Authors: Croshaw Dean A. , Glenn Travis C.
Published: November 2003

We describe polymerase chain reaction (PCR) primers and amplification conditions for seven tetranucleotide microsatellite DNA loci isolated from the southern dusky salamander (Desmognathus auriculatus). Primers were tested on 16 individuals from one population in Aiken County, South Carolina. We detected an average of 6.57 alleles per locus, an observed heterozygosity range of 0.44–0.94, and high polymorphic information contents (mean of 0.68).
Isolation of polymorphic microsatellite markers for British Euphrasia L.
Authors: French G. C. , Hollingsworth P. M. , Ennos R. A.
Published: November 2003

Euphrasia species in Britain attract a large amount of conservation attention due to the recognition of numerous endemic taxa in what is essentially a species‐poor flora. To develop a set of research tools to investigate the evolutionary processes underlying this diversification, a membrane enrichment procedure has been used to isolate five polymorphic microsatellite loci from Euphrasia nemorosa (Pers.) Wallr. These loci amplify polymorphic products in several other British Euphrasia species.
Isolation and characterization of eight highly variable microsatellite markers in the Pacific jumping mouse (Zapus trinotatus)
Authors: Vignieri S. N.
Published: November 2003

In patchily distributed populations it is possible to investigate gene flow and relatedness at multiple scales. Using an enrichment procedure, I developed a suite of eight microsatellite markers in such a heterogeneously distributed species, the Pacific jumping mouse (Zapus trinotatus). The identified loci were highly polymorphic (10–36 alleles per locus) and will be valuable for investigating this species at multiple levels, from that of parentage and breeding structure within a subpopulation, to gene‐flow and population structure across populations.
Not an Innocent Pursuit: The Politics of a ‘Jewish’ Genetic Signature
Authors: Azoulay Katya Gibel
Published: November 2003

This commentary questions the presumption in genetic research that a biological connection exists between populations identified as Jewish. The author emphasises that identifying individuals as Jewish based on biological criteria is a sociological process that can draw attention away from other social mechanisms affecting identity construction. She also encourages critical consideration of the possible racialised thinking behind genetic anthropology studies, and the language used to express genetic findings. In conclusion, she calls for a radical cultural shift in the kind of knowledge valued as significant, relevant, and beneficial to the people on whom genetic ancestry studies are carried out and she asks for attention to the political contexts surrounding all such research.
Blondes, Lost and Found: Representations of Genes, Identity, and History
Authors: Pálsson Gísli , Helgason Agnar
Published: November 2003

Research carried out during recent decades has revealed our genome not only to be a unique mine of information about health, disease and the human condition, but also about the origin and dispersal history of the species. In this context, the genome is simply an additional source of information about human history, epistemologically no different from other historical sources. However, media and public interpretation of genetic studies of human history are complicated by the wider connotations of genes as the determinants of hereditary features and identity. We discuss two examples of media and public fascination with the interrelated themes of history, identity and heredity, pointing out some implications of historical research using genetic data in the context of our own ongoing study of Inuit groups in Greenland and Victoria Island, Canada.
Pharmacodynamics of H1‐antihistamines: from concept to reality
Authors: Frossard N.
Published: November 2003

Pharmacodynamics are designed to give objective criteria to the understanding and assessment of the potency and consistency of activity of antihistamines. They allow a determination of the onset of action in the skin, and of their duration of action, which is particularly important for defining a once‐ or twice‐a‐day dosing, for instance. They also predict the antihistaminic potency in the skin, studying the cutaneous reactivity to histamine at specific time‐points, or over a 24‐h period. These pre‐clinical studies assess drug characteristics, which is helpful in understanding their clinical efficacy. Pharmacodynamics are thus a necessary step in clinical studies, and important in the assessment of the clinical efficacy of a drug in the allergic patient.
Negative representations of the self/spouse and marital distress
Authors: Kurdek Lawrence A.
Published: November 2003

The link between marital distress and negative representations of both the self and the spouse was examined with data from an initial sample of 538 married couples studied over the first four years of marriage (Study 1) and 98 of these couples studied in their tenth year of marriage (Study 2). Findings from Study 1 indicated that, for both husbands and wives, representations of the self and representations of the spouse accounted for unique variability in distress. Across spouses, representations of the spouse accounted for more of the variability in distress than did representations of the self. Cross–spouse effects were especially pronounced for husbands such that their distress was linked to wives’ representations. Findings from Study 2 with self/spouse measures anchored to the marital context replicated this pattern. Findings support the view that marital distress is uniquely influenced by models of both the self and the spouse, that representations of the self and the spouse are dynamic relationship schemas, that models of the self and the spouse can be meaningfully assessed within the marital context, and that negative representations of the spouse—particularly those of wives—are especially diagnostic of marital distress.
Epidemiology of Helicobacter pylori infection
Authors: Malaty Hoda M. , Nyren Olof
Published: November 2003

Transmission of the infection revealed in many articles an important role of the mothers in transmitting the infection to their children. The epidemiology and risk factors of Helicobacter pylori infection were examined. The seroprevalence of the infection in different populations as well as colonization of the infection in childhood was reported. Moreover, this year attention was aimed at examining the associations between Helicobacter pylori with gastrointestinal and nongastrointestinal diseases.
Beta Receptor Blockade Potentiates the Antiarrhythmic Actions of d‐Sotalol on Reentrant Ventricular Tachycardia in a Canine Model of Myocardial Infarction
Authors: KASSOTIS JOHN , SAUBERMAN ROY B. , CABO CANDIDO , WIT ANDREW L. , COROMILAS JAMES
Published: November 2003

Introduction: The importance of beta receptor blockade for the antiarrhythmic action of sotalol has not been completely elucidated. We determined how beta receptor blockade interacts with the effects of potassium channel blockade on reentrant circuits.

Methods and Results: Sustained ventricular tachycardia was induced by programmed stimulation in dogs 4 days after left anterior coronary artery occlusion and reentrant circuits in the epicardial border zone (EBZ) mapped. The effects of the beta receptor‐blocking drug, esmolol, the potassium channel‐blocking drug d‐sotalol, which lacks beta receptor‐blocking effects, and the combination of the two drugs on the reentrant circuits that cause tachycardia were determined. Esmolol did not alter the ability to induce tachycardia. Small changes in the location or extent of lines of block in reentrant circuits accounted for small decreases or increases in tachycardia cycle lengths. d‐Sotalol prolonged the lines of block in reentrant circuits, slowed propagation around the circuits, and prolonged tachycardia cycle length, but it did not stop tachycardia or prevent the induction of tachycardia. The combination of esmolol and d‐sotalol prevented the initiation of sustained tachycardia. The stimulated premature impulse either blocked before reentering or traversed the circuit several times prior to blocking in a region of fractionated electrograms. The addition of esmolol to d‐sotalol abolished the reverse use‐dependent effects of d‐sotalol alone on effective refractory period (ERP) and significantly prolonged ERP in the area of the reentrant circuit.

Conclusion: Beta receptor blockade is important for the antiarrhythmic effects of d,l‐sotalol on reentrant ventricular tachycardia in this model. The mechanism is speculative but may involve potentiation of d‐sotalol actions to prolong ERP or effects on gap junctions. (J Cardiovasc Electrophysiol, Vol. 14, pp. 1233‐1244, November 2003)
Incidence and Characteristics of Type‐2 Breaks in Response to Antitachycardia Pacing Therapy in Implantable Cardioverter Defibrillator Patients
Authors: SHARMA VINOD , DeGROOT PAUL J. , WATHEN MARK S.
Published: November 2003

Introduction: Antitachycardia pacing (ATP) effectively treats monomorphic ventricular tachycardia (VT). The VT may cease immediately upon ATP completion (type‐1 break), or it may persist or change to another tachyarrhythmia for one or more beats before termination (type‐2 break). We investigated the prevalence and characteristics of type‐2 breaks in ICD patients.

Methods and Results: We analyzed VT episodes with stored electrograms that had at least one ATP therapy delivered in PainFREE Rx trial, a multicenter trial with 220 coronary artery disease patients. Further subanalysis was performed by classifying the VT as slow or fast based on the cycle length (CL); slow VT: CL >320 ms, fast VT: 240 ≤CL ≤320 ms. To assess the effect of ATP on VT, comparison was performed of pre‐ATP and post‐ATP CL variability, average CL, and morphology. A total of 514 episodes (264 slow VT and 250 fast VT) were analyzed. The burst ATP terminated 457 (89%; 239 slow VT and 218 fast VT) of 514 episodes. Forty five (10%) episodes in 18 (32%) patients had type‐2 breaks. The mean number of beats during type‐2 breaks was 5.4 ± 3.1 (median 4). The mean time for episode termination measured from the end of ATP to return of first sinus/paced beat was 2.9 ± 1.2 seconds (median 2.6). The VT CL variability increased by 150% after ATP delivery. The ATP affected either VT CL or morphology, or both of 36 (80%) type‐2 breaks (9% accelerated, 47% decelerated, 22% changed in morphology only). Among the 9 (20%) episodes that remained unchanged in morphology and CL, four episodes (9%) were unaffected by ATP.

Conclusion: Approximately 10% of VT episodes that were successfully terminated with burst ATP therapy had type‐2 breaks. Type‐2 breaks are associated with an increase in CL variability. Approximately 9% of all type‐2 episodes may be spontaneously terminating nonsustained VT given that ATP did not affect these episodes in any way. (J Cardiovasc Electrophysiol, Vol. 14, pp. 1156‐1162, November 2003)
Randomized Controlled Trial of Fixed Rate Versus Rate Responsive Pacing After Radiofrequency Atrioventricular Junction Ablation:
Authors: DUFF HENRY J. , RAJ SATISH R. , EXNER DEREK V. , SHELDON ROBERT S. , ROACH DAN , MITCHELL L. BRENT , WYSE D. GEORGE , MORCK MARGARET , GILLIS ANNE M.
Published: November 2003

Introduction: Ablation of the AV junction is a widely accepted treatment of drug‐refractory atrial fibrillation. Long‐term pacing of the right ventricular (RV) apex following AV junction ablation can result in adverse cardiac remodeling. However, anecdotal studies report that pacing too slowly following AV junction ablation was associated with propensity to sudden cardiac death. The aim of this study was to provide information about the balance between measures of quality of life versus measures of electrical remodeling achieved by pacing with different rate modalities in a randomized pilot clinical trial.

Methods and Results: Patients with permanent atrial fibrillation were randomized to VVI (80 beats/min) versus VVIR (minimum rate 80 beats/min), whereas patients with paroxysmal atrial fibrillation were randomized to DDI versus DDDR pacing at discharge from hospital. Serially, measurements of exercise capacity, quality of life, cycle length dependence of QT dispersion (QTdisp), RV refractoriness, and the incidence of nonsustained ventricular tachycardia were made in 28 patients over a 6‐month follow‐up period. Time‐dependent increases in QTdisp were observed in patients randomized to the rate responsive mode (RR‐ON) but only when paced at 40 beats/min. This was paralleled by time‐dependent increases in RV refractoriness (270 ± 11 ms at baseline to 302 ± 5 ms at 6 months) in patients with RR‐ON. RR‐ON also was associated with trends to an increasing incidence of episodes of nonsustained ventricular tachycardia and worsening of some measures of quality of life. Exercise capacity was not substantially different in the randomized groups.

Conclusion: Rate responsive pacing results in electrical remodeling of the ventricle following AV junction ablation, but exercise capacity was similar in groups with RR‐ON or RR‐OFF. (J Cardiovasc Electrophysiol, Vol. 14, pp. 1163‐1170, November 2003)
Optical Mapping of Transmural Activation Induced by Electrical Shocks in Isolated Left Ventricular Wall Wedge Preparations
Authors: SHARIFOV OLEG F. , FAST VLADIMIR G.
Published: November 2003

Introduction: It is believed that electrical shocks interrupt fibrillation by directly stimulating the bulk of ventricular myocardium in excitable states, but how shocks activate intramural tissue layers is not known. In this study, Vm responses and transmural activation patterns induced by shocks during diastole were measured in isolated coronary perfused preparations of porcine left ventricle.

Methods and Results: Rectangular shocks (duration = 10 ms; field strength, E = 1–44 V/cm) were applied across preparations (thickness = 14.9 ± 2.5 mm, n = 9) via large mesh electrodes during diastole or action potential (AP) plateau. Vm responses at the transmural surface were measured using optical mapping technique (resolution = 1.2 mm). Depending on shock strength, three types of Vm responses were observed. (1) Weak shocks (E ∼ 1–4 V/cm) applied in diastole induced APs with simple monophasic upstrokes. The latency and time of transmural activation (TTA) rapidly decreased with increasing shock strength. Earliest activation occurred predominantly at the cathodal side of preparations in the areas that exhibited maximal ΔVm during AP plateau. (2) Intermediate shocks (E ∼ 4–23 V/cm) induced monophasic and biphasic upstrokes that were paralleled with predominantly negative plateau ΔVm. Activation was initiated at multiple transmural sites and rapidly spread across the myocardial wall (TTA = 0.6 ± 0.2 ms). (3) Very strong shocks (E ∼ 23–44 V/cm) could cause triphasic upstrokes, likely reflecting occurrence of membrane electroporation, and delayed activation (TTA = 6.7 ± 3.8 ms) at sites of largest negative plateau ΔVm.

Conclusion: Shocks applied during diastole cause direct and rapid (within 1 ms) activation of ventricular bulk over a wide range of shock strengths, supporting the excitatory hypothesis of defibrillation. Very strong shocks can cause multiphasic Vm responses and delayed activation. (J Cardiovasc Electrophysiol, Vol. 14, pp. 1215‐1222, November 2003)
Up‐Regulation of Connexin45 in Heart Failure
Authors: YAMADA KATHRYN A. , ROGERS JOSEPH G. , SUNDSET RUNE , STEINBERG THOMAS H. , SAFFITZ JEFFREY E.
Published: November 2003

Introduction: Heart failure is associated with reduced expression of the major gap junction protein connexin43 (Cx43), which may contribute to arrhythmias and sudden cardiac death in this patient population. Other cardiac connexins may be altered as well. Because connexin45 (Cx45) has been shown to colocalize with Cx43, we determined whether the number, size, or distribution of Cx45 gap junctions is altered in the failing heart.

Methods and Results: Cx45 expression levels were measured by immunoblotting and quantitative immunostaining in failing and control human left ventricles. Total Cx45 protein was significantly (P = 0.021) up‐regulated 1.8‐fold in failing hearts. Cx45 immunohistochemical signal was increased by 80% (P = 0.005) due to a 3.5‐fold increase in the number of gap junctions containing Cx45. Cx45 mRNA was not altered in failing hearts, suggesting reduced degradation of Cx45 protein in the failing heart. Cx43 signal, on the other hand, was reduced by 49% in failing hearts. Double‐label experiments demonstrated colocalization of Cx45 and Cx43 in the same gap junctions.

Conclusion: Cx45 is markedly enhanced in the failing heart. Up‐regulation of Cx45 in conjunction with down‐regulation of Cx43 could result in abnormal impulse propagation and generation of ventricular arrhythmias, thereby predisposing patients in heart failure to sudden cardiac death. (J Cardiovasc Electrophysiol, Vol. 14, pp. 1205‐1212, November 2003)
Atrial Fibrillation:
Authors: LEMERY ROBERT
Published: November 2003

Percutaneous radiofrequency ablation of pulmonary vein potentials has been shown to eliminate atrial fibrillation in a subset of patients characterized by frequent and repetitive paroxysms of atrial fibrillation. However, pulmonary vein disconnection has had only limited success at curing patients with persistent atrial fibrillation. In those patients, left atrial substrate modification and linear ablation strategies have had substantially higher success rates. Furthermore, in other patients, elimination of right atrial triggers (superior vena cava) or modification of right atrial substrate has been required for elimination of atrial fibrillation. Finally, the realization that the coronary sinus is a third atrial chamber that can both initiate and maintain atrial fibrillation has provided new understanding to the pathogenesis of atrial fibrillation. From a clinical perspective, only careful anatomic and mapping strategies specifically aimed at each subset of patients with atrial fibrillation will allow for pattern recognition and establish which mechanisms are responsible for initiation and maintenance of atrial fibrillation. Only the latter will allow for increased long‐term success rates of ablation of atrial fibrillation. (J Cardiovasc Electrophysiol, Vol. 14, pp. 1248‐1251, November 2003)
Experimental Study and Modeling of GTA Welding Process
Authors: Jou Min
Published: November 2003

It has been well recognized that the geometry of weld pool plays a fundamental role in determining the mechanical properties of weld joints. In this research, a series of experiment has been conducted to investigate the interaction and correlation of welding current, voltage, welding speed, and arc length affecting the formation of weld pool. The effect of arc length on arc efficiency and heat distribution parameter are also examined and addressed in this paper. In addition to the experimental study, a three-dimensional finite element model has been developed to analyze transient heat flow and to predict the formation of the weld pool. The correlation among the parameters including welding current, voltage, welding speed, arc length, open-loop response and the characteristic geometry of weld pool are established. The 3-D FEM can calculate not only the transient thermal histories but also the sizes of weld pool in single-pass arc welding. In order to obtain quality welds, this model will determine the effect of arc length on the formation of weld. Furthermore, the effects of welding parameters on the Gaussian heat source parameters (arc efficiency and heat distribution parameter) are also studied. The experimental calibration and verification are carried out to verify the numerical model. Experimental data are consistent and in quantitative agreement with values from FEM simulations.
Influence of Exit Surface Angle on Drilling Burr Formation
Authors: Min Sangkee , Dornfeld David A. , Nakao Yohichi
Published: November 2003

The influence of an exit surface angle on drilling burr formation was analyzed. The experimental research found that a burr forms on only a certain portion of a hole when an exit surface is not perpendicular to a drill path. An effective interaction angle was newly defined and the concept of degree of plastic deformation was introduced in order to explain this phenomenon. The burr forming location predicted from the effective interaction angle was verified with experimental results.
Increased brain radioresistance after supralethal irradiation
Authors: Chaput Raymond L. , Berardo Peter A.
Published: November 2003

Clinical symptoms and performance were evaluated after shuttlebox‐trained miniature pigs received two 4400‐rad doses separated by time intervals of 10 − 4‐30 min. The doses were delivered to the head by 45‐MeV electrons from the AFRRI electron linear accelerator (LINAC). There was no significant difference in neurological symptons (Convulsions, coma, ataxia) or in performance after the second dose between animals that received the two doses 10 − 4 or 0.3 min apart. As the time interval between doses was increased from 0.3 min, however, neurological symptoms declined and performance improved markedly after the second dose. When the doses were 30 min apart, the pigs showed no decrease in performance within the intial 30‐min postirradiation. It was concluded that more than physiochemical processes were involved in the increased radioresistance to the second dose of radiation.
Single crystal sapphire: A thermally stimulated conductance (TSC) radiation dosimeter
Authors: Fullerton G. D. , Moran P. R.
Published: November 2003

We show measurement of thermally stimulated conduction (TSC) in high‐purity sapphire to be a potentially useful technique for ionizing radiation dosimetry. The TSC thermogram, conduction current vs temperature or time, has current peaks that are proportional in height to irradiation. The peak height response to x rays is: (1) linear with doses from 10 mR to 100 R (60Co energy); (2) useful from 10 mR to 104 R (60Co energy); (3) reusable with no additional treatment for exposures less than 1000 R; (4) exposure rate independent from at least 0.12 mR/sec to 3.2 R/sec; (5) stable; and (6) reasonably similar to tissue response as a function of energy. The stability of response, simplicity of instrumentation requirements, and dependable supply of materials at competitive price with other dosimetry systems favor application of this technique.
An extrapolation chamber for the calibration of beta‐ray applicators
Authors: Payne W. H. , Waggener R. G.
Published: November 2003

A simple, easily constructed extrapolation chamber is described for the calibration of Β‐ray applicators.
A theoretical calculation of the exposure rate constant for radium‐226
Authors: Payne William H. , Waggener Robert G.
Published: November 2003

Until recently, the photon spectrum of 226Ra has not been known with sufficient accuracy to permit calculation of the exposure rate constant. Workers concerned with calculations involving this constant have relied upon measured values. The authors have taken compiled photon spectra authored by M. J. Martin and P. H. Blichert‐Toft in Nuclear Data Tables along with photon cross sections authored by E. Storm and H. Israel in Nuclear Data Tables and calculated theoretical values for the exposure rate constant for 226Ra. Using the most recent 72‐line spectrum for 226Ra and its daughter products, an exposure rate constant of 12.44 R‐cm2/mg‐h was obtained for unfiltered radium. A large portion of this value was contributed by some low energy x‐ray lines which would not be seen in even a very lightly filtered source. Using a 3‐mm‐o.d. sphere (90%‐Pt, 10%‐Ir, 0.5‐mm filter), a value of 8.12 R‐cm2/mg‐h was obtained for the filtered source. Primary, scattered, and bremsstrahlung contributions to this value were 7.610, 0.363, and 0.149, respectively. This value is within 1.6% of the presently accepted value for 226Ra, 8.25.
Experimental determination of the need for multitaper collimators for neutron radiotherapy
Authors: Jones K. M. , Kelsey C. A.
Published: November 2003

A 52.5‐cm‐long steel collimator for 15‐MeV neutron therapy beams has been evaluated in terms of the distribution of the collimator‐scattered neutrons in the field and penumbra, the distribution in the collimator of the neutron scattering sites, and the energy of the neutrons scattered to one position in the penumbra, in order to assess the need for multiple tapers on such collimators. The associated particle technique was used to eliminate background neutrons from the measurement. We conclude that because collimator‐scattered neutrons constitute only a small part of the neutron flux in the field and most of the scattered neutrons have energies greater than 12 MeV, double‐taper collimators are not necessary.
Perturbation of neutron dose distributions by lung tissue
Authors: McGinley Patton H. , McLaren John R.
Published: November 2003

The influence of lung tissue on depth dose distributions, produced by beams of fast neutrons (generated at the Naval Research Laboratory cyclotron by bombarding a thick Be target with 35‐MeV deuterons) was determined. Muscle‐equivalent ionization chambers were utilized in conjunction with thermoluminescent dosimeters to establish the neutron and gamma ray‐dose deposited in a phantom of the thoracic region of the body containing lung components. All irradiations were carried out at a target–skin distance of 125 cm with neutron beams of 10 × 10‐cm field size at the surface of the phantom. From these measurements, the authors conclude that the presence of lung tissue results in higher dose levels for points at depths greater than the midpoint of the lungs as a result of the increased transmission of neutrons by low‐density lung tissue. An examination of the dose measurements revealed that the portion of the total dose due to gamma rays is of the order of 4–10% for points in lung and muscle‐equivalent fluid.
Acoustical properties of blood: A look at the basic assumptions
Authors: Ahuja Avtar Singh
Published: November 2003

The results from the literature on acoustics in suspensions, excluding the phenomena of relaxation, have been applied to study the effects of red‐cell and plasma densities, compressibilities, viscosities, thermal conductivities, and surface tension on the propagation of sound in blood. For the calculations of the viscous and the thermal absorptions and of the velocity of sound in blood, the red cell may be treated as a rigid spherical particle containing the same volume. For the calculation of the thermal absorption, the erythrocyte may be treated as a spherical particle of finite thermal conductivity at all frequencies; but for the calculation of the velocity of sound, the effect of heat conduction can be ignored above 1 MHz and Wood's sound velocity formula may be used. The calculated sound absorption due to shear viscosity and thermal conduction in whole blood constitutes a significant portion (about 60% or more) of the measured value of the total absorption toward the lower‐frequency range (1 MHz or less) and a negligible portion (about 15% or less) of the total absorption toward the higher‐frequency range (10 MHz or more).
Verification of a practical method for making individual corrections for inhomogeneities in the thorax
Authors: Wright Ann E. , Strockbine Melvin F.
Published: November 2003

Cobalt‐60 teletherapy dose calculations utilizing a standard correction factor for thorax inhomogeneities can result in dose error due to patient variability. Individual intracavitary measurements avoid this error but are impractical for routine clinical use. A graph has been constructed relating the ratio of measurements made with and without the patient in the beam to an equivalent water depth. With an ordinary ion chamber secured to the beamstopper, the dose was integrated during a 1‐min rotation. A known water depth was used to derive apparent linear attenuation coefficients which, with the equation , enabled construction of the graph. To verify the method, tubes with dosimeters were positioned at the axis of rotation during the first treatment of patients with esophageal tumors. Agreement of corrected dose with measured dose is within 3% for 360 deg rotational treatment; uncorrected dose calculations would have resulted in errors of 5%–21%.
Current‐limiting resistor for polarizing batteries
Authors: Balter Stephen
Published: November 2003

The addition of a current limiting resistor to the high‐voltage polarizing batteries of an ionization chamber is described to reduce accidental shock to personnel and possible equipment damage.
ThepqrABOperon Is Responsible for Paraquat Resistance inStreptomyces coelicolor
Authors: Cho You-Hee , Kim Eun-Ja , Chung Hye-Jung , Choi Jae-Hyun , Chater Keith F. , Ahn Bo-Eun , Shin Jung-Ho , Roe Jung-Hye
Published: November 2003

Paraquat (methyl viologen)-resistant mutants ofStreptomyces coelicolorA3(2) that grew and sporulated normally in the presence of paraquat were isolated. Based on the positions of the mutant loci in the genetic map, we isolated thepqr(paraquat resistance) gene whose mutation (pqr501) caused a dominant paraquat-resistant phenotype. Thepqrlocus consists of two genes (pqrAandpqrB) that form a transcription unit. ThepqrAgene encodes a protein with a TetR-like DNA-binding motif, and thepqrBgene encodes a putative efflux pump of the major facilitator superfamily. Thepqr501mutation was a base substitution changing arginine-18 to glutamine (R18Q) near the helix-turn-helix motif in PqrA. ApqrAnull mutant exhibited similar paraquat resistance, and an increase in the amount ofpqrApromoter-driven transcripts of about eightfold was observed for thepqrA501mutant. These results suggest that PqrA is a negative regulator of its own operon. Deletion of thepqrABoperon caused cells to be very sensitive to paraquat, consistent with the prediction that PqrB may function as a paraquat-efflux pump. Purified PqrA protein specifically bound to thepqrApromoter region, whereas mutant R18Q protein did not, indicating that PqrA is a direct autoregulator of its own operon.
Identification and Characterization of a Peptidoglycan Hydrolase, MurA, ofListeria monocytogenes, a Muramidase Needed for Cell Separation
Authors: Carroll Shannon A. , Hain Torsten , Technow Ulrike , Darji Ayub , Pashalidis Philippos , Joseph Sam W. , Chakraborty Trinad
Published: November 2003

A novel cell wall hydrolase encoded by themurAgene ofListeria monocytogenesis reported here. Mature MurA is a 66-kDa cell surface protein that is recognized by the well-characterizedL. monocytogenes-specific monoclonal antibody EM-7G1. MurA displays two characteristic features: (i) an N-terminal domain with homology to muramidases from several gram-positive bacterial species and (ii) four copies of a cell wall-anchoring LysM repeat motif present within its C-terminal domain. Purified recombinant MurA produced inEscherichia coliwas confirmed to be an authentic cell wall hydrolase with lytic properties toward cell wall preparations ofMicrococcus lysodeikticus. An isogenic mutant with a deletion ofmurAthat lacked the 66-kDa cell wall hydrolase grew as long chains during exponential growth. Complementation of the mutant strain by chromosomal reintegration of the wild-type gene restored expression of this murein hydrolase activity and cell separation levels to those of the wild-type strain. Studies reported herein suggest that the MurA protein is involved in generalized autolysis ofL. monocytogenes.
Planktonic invaders of the St. Lawrence estuarine transition zone: environmental factors controlling the distribution of zebra mussel veligers
Authors: Barnard Christine , Frenette Jean-Jacques , Vincent Warwick F
Published: November 2003

The St. Lawrence estuarine transition zone (ETZ) is a productive ecosystem supporting a larval fish nursery. Since 1994, Dreissena polymorpha veligers have become the dominant zooplankton (up to 260 individuals·L1). The environmental factors controlling their distribution across the ETZ and their potential impact on the plankton were determined. Their horizontal distribution was limited by salinity, with maximum decreases in concentration at 2. A sharp decline in prey availability at >2 may be a secondary stressor for the veligers, in addition to the direct effects of salinity. Their vertical distribution was homogeneous throughout the water column, even in the presence of a pycnocline. Redundancy analysis showed that veliger concentrations were positively correlated with temperature and turbidity and negatively correlated with salinity and total phosphorus. Veligers were also positively correlated with chlorophyll a and picophytoplankton concentrations, suggesting little effect on their phytoplankton prey. Moreover, the veligers were positively correlated with the sestonic ratio of particulate to total phosphorus, indicating their positive association with good food quality. The veligers appear to have no severe negative impacts on the ETZ plankton community and are restricted to favourable conditions for their survival in the upstream, low salinity region of the ETZ.