bluuebunny/crossref_metadata_2025 huggingface dataset:
Long-chain polyunsaturated fatty acids and the pathophysiology of myalgic encephalomyelitis (chronic fatigue syndrome)
Authors: Puri B K
Published: August 2006

Evidence is put forward to suggest that myalgic encephalomyelitis, also known as chronic fatigue syndrome, may be associated with persistent viral infection. In turn, such infections are likely to impair the ability of the body to biosynthesise n-3 and n-6 long-chain polyunsaturated fatty acids by inhibiting the δ-6 desaturation of the precursor essential fatty acids—namely, α-linolenic acid and linoleic acid. This would, in turn, impair the proper functioning of cell membranes, including cell signalling, and have an adverse effect on the biosynthesis of eicosanoids from the long-chain polyunsaturated fatty acids dihomo-γ-linolenic acid, arachidonic acid and eicosapentaenoic acid. These actions might offer an explanation for some of the symptoms and signs of myalgic encephalomyelitis. A potential therapeutic avenue could be offered by bypassing the inhibition of the enzyme δ-6-desaturase by treatment with virgin cold-pressed non-raffinated evening primrose oil, which would supply γ-linolenic acid and lipophilic pentacyclic triterpenes, and with eicosapentaenoic acid. The γ-linolenic acid can readily be converted into dihomo-γ-linolenic acid and thence arachidonic acid, while triterpenes have important free radical scavenging, cyclo-oxygenase and neutrophil elastase inhibitory activities. Furthermore, both arachidonic acid and eicosapentaenoic acid are, at relatively low concentrations, directly virucidal.
Special problems of children with myalgic encephalomyelitis/chronic fatigue syndrome and the enteroviral link: Table 1
Authors: Colby J
Published: August 2006

Since 1997, it has been known that myalgic encephalomyelitis/chronic fatigue syndrome constitutes the biggest cause of long-term sickness leading to absence from school, in both staff and pupils. The scale of the problem in children is substantial, and the pattern of illness in schools suggests a prominent role for viral infection—for example, the clustering of cases. The Dowsett–Colby study of 1997, researching long-term sickness, reported on a school roll of 333 024 pupils and 27 327 staff, and found a prevalence of long-term sickness in 70 of 100 000 pupils and 500 of 100 000 staff; 39% of cases were in clusters of three or more. The peak age was 14–16 years. The illness is known to be potentially severe and chronic. In addition, the Tymes Trust has reported that many affected children struggle for recognition of their needs, and are bullied by medical and educational professionals. Children should have time to recover sufficiently before returning to school; sustainable, energy-efficient and often home-based education is important here to fulfil legal obligations. Research is needed on viruses that trigger childhood myalgic encephalomyelitis—for example, enteroviruses—and on the neurocognitive defects caused by myalgic encephalomyelitis. We should recognise the value of previous biological research and records of outbreaks, and I recommend that myalgic encephalomyelitis be made notifiable owing to the encephalitic nature of the effects commonly reported in this illness.
Unique features of the apoptotic endonuclease DFF40/CAD relative to micrococcal nuclease as a structural probe for chromatinThis paper is one of a selection of papers published in this Special Issue, entitled 27th International West Coast Chromatin and Chromosome Conference, and has undergone the Journal's usual peer review process.
Authors: Widlak Piotr , Garrard William T.
Published: August 2006

The gold standard for studies of nucleosomal chromatin structure for the past 30 years has been the enzyme micrococcal nuclease (MNase). During the course of our studies on the elucidation of the mechanism of action of the apoptotic nuclease DNA fragmentation factor-40 / caspase-activated deoxyribonuclease (DFF40/CAD) on naked DNA and chromatin substrates, it became clear that this enzyme is superior in certain respects to MNase for studying several aspects of chromatin structure. Here we review our published results supporting this statement. Relative to MNase, we have found that DFF40/CAD has the following properties: (i) it does not cut within nucleosomes to generate subnucleosomal DNA fragments; (ii) it is more specific for the linker regions between nucleosomes; (iii) it lacks exonuclease activity; (iv) it is specific for double-stranded DNA and makes exclusively double-stranded breaks; and (v) it attacks histone-H1-containing chromatin more efficiently. Taken together, these facts explain why DFF40/CAD generates sharper oligonucleosomal DNA ladders compared with those generated by MNase. We therefore recommend the following uses for DFF40/CAD for chromatin research: nucleosome isolation, chromatin-remodeling assays, repeat length measurements, and nucleosome-positioning assays along specific sequences. Other uses include footprinting assays of transcription factor positions, shearing chromatin for immunopreciptitation experiments (ChIP), and shearing DNA for recombinant DNA library preparation or for shotgun cloning for sequencing.
In vitro chromatin self-association and its relevance to genome architectureThis paper is one of a selection of papers published in this Special Issue, entitled 27th International West Coast Chromatin and Chromosome Conference, and has undergone the Journal's usual peer review process.
Authors: Lu Xu , Klonoski Joshua M. , Resch Michael G. , Hansen Jeffrey C.
Published: August 2006

Chromatin in a eukaryotic nucleus is condensed through 3 hierarchies: primary, secondary, and tertiary chromatin structures. In vitro, when induced with cations, chromatin can self-associate and form large oligomers. This self-association process has been proposed to mimic processes involved in the assembly and maintenance of tertiary chromatin structures in vivo. In this article, we review 30 years of studies of chromatin self-association, with an emphasis on the evidence suggesting that this in vitro process is physiologically relevant.
Physical methods used to study core histone tail structures and interactions in solutionThis paper is one of a selection of papers published in this Special Issue, entitled 27th International West Coast Chromatin and Chromosome Conference, and has undergone the Journal's usual peer review process.
Authors: Wang Xiaodong , Hayes Jeffrey J.
Published: August 2006

The core histone tail domains are key regulatory elements in chromatin. The tails are essential for folding oligonucleosomal arrays into both secondary and tertiary structures, and post-translational modifications within these domains can directly alter DNA accessibility. Unfortunately, there is little understanding of the structures and interactions of the core histone tail domains or how post-translational modifications within the tails may alter these interactions. Here we review NMR, thermal denaturation, cross-linking, and other selected solution methods used to define the general structures and binding behavior of the tail domains in various chromatin environments. All of these methods indicate that the tail domains bind primarily electrostatically to sites within chromatin. The data also indicate that the tails adopt specific structures when bound to DNA and that tail structures and interactions are plastic, depending on the specific chromatin environment. In addition, post-translational modifications, such as acetylation, can directly alter histone tail structures and interactions.
The multiple faces of Set1This paper is one of a selection of papers published in this Special Issue, entitled 27th International West Coast Chromatin and Chromosome Conference, and has undergone the Journal's usual peer review process.
Authors: Dehé Pierre-Marie , Géli Vincent
Published: August 2006

In Saccharomyces cerevisiae, H3 methylation at lysine 4 (H3K4) is mediated by Set1. Set1 is a large protein bearing a conserved RNA recognition motif in addition to its catalytic C-terminal SET domain. The SET and RRM domains are conserved in Set1 orthologs from yeast to humans. Set1 belongs to a complex of 8 proteins, also showing a striking conservation, most subunits being required to efficiently catalyze methylation of H3K4. The deletion of SET1 is not lethal but has pleiotropic phenotypes. It affects growth, transcriptional activation, repression and elongation, telomere length regulation, telomeric position effect, rDNA silencing, meiotic differentiation, DNA repair, chromosome segregation, and cell wall organization. In this review, we discuss the regulation of H3K4 methylation and try to link Set1 activity with the multiple phenotypes displayed by cells lacking Set1. We also suggest that Set1 may have multiple targets.
Ribosomal chromatin organizationThis paper is one of a selection of papers published in this Special Issue, entitled 27th International West Coast Chromatin and Chromosome Conference, and has undergone the Journal's usual peer review process.
Authors: Huang Sui , Rothblum Lawrence I. , Chen Danyang
Published: August 2006

Mammalian cells contain approximately 400 copies of the ribosomal RNA genes organized as tandem, head-to-tail repeats spread among 6–8 chromosomes. Only a subset of the genes is transcribed at any given time. Experimental evidence suggests that, in a specific cell type, only a fraction of the genes exists in a conformation that can be transcribed. An increasing body of study indicates that eukaryotic ribosomal RNA genes exist in either a heterochromatic nucleosomal state or in open euchromatic states in which they can be, or are, transcribed. This review will attempt to summarize our current understanding of the structure and organization of ribosomal chromatin.
Epigenetic tête-à-tête: the bilateral relationship between chromatin modifications and DNA methylationThis paper is one of a selection of papers published in this Special Issue, entitled 27th International West Coast Chromatin and Chromosome Conference, and has undergone the Journal's usual peer review process.
Authors: D’Alessio Ana C. , Szyf Moshe
Published: August 2006

The epigenome, which comprises chromatin, associated proteins, and the pattern of covalent modification of DNA by methylation, sets up and maintains gene expression programs. It was originally believed that DNA methylation was the dominant reaction in determining the chromatin structure. However, emerging data suggest that chromatin can affect DNA methylation in both directions, triggering either de novo DNA methylation or demethylation. These events are particularly important for the understanding of cellular transformation, which requires a coordinated change in gene expression profiles. While genetic alterations can explain some of the changes, the important role of epigenetic reprogramming is becoming more and more evident. Cancer cells exhibit a paradoxical coexistence of global loss of DNA methylation with regional hypermethylation.
Effects of sulfonylureas on left ventricular mass in type 2 diabetic patients
Authors: Lee Tsung-Ming , Lin Mei-Shu , Tsai Chang-Her , Huang Chen-Ling , Chang Nen-Chung
Published: August 2006

Myocardial ATP-sensitive potassium (KATP) channels have been implicated in attenuating cardiac hypertrophy by modulating endothelin-1 concentrations. Sulfonylureas differ in their affinity for cardiac KATPchannels and therefore may vary in their effects on left ventricular (LV) mass. We sought to determine the differential effects of sulfonylureas on LV mass in type 2 diabetic patients. All patients had been taking glibenclamide for more than 3 mo before being randomized to either switch to an equipotent dose of gliclazide or continue glibenclamide. A total of consecutive 240 diabetic patients were randomized into glibenclamide, gliclazide, a combination of glibenclamide and nicorandil, or gliclazide and nicorandil for 6 mo. In the gliclazide-treated group, the LV mass index was significantly decreased compared with that in the glibenclamide-treated groups. Nicorandil administration significantly reduced LV mass in glibenclamide-treated patients compared with patients treated with glibenclamide alone. Measurements of endothelin-1 concentrations mirrored the functional status of KATPchannel. Multivariate analysis revealed that regression of LV mass was significantly correlated only with the changes in endothelin-1 ( P < 0.0001). Our results show that KATPchannels may play a pathogenetic role, probably through an endothelin-1-dependent pathway, in diabetes mellitus-related ventricular hypertrophy. Patients treated with gliclazide may have a beneficial effect in attenuating ventricular mass.
Upregulation of γ-catenin compensates for the loss of β-catenin in adult cardiomyocytes
Authors: Zhou Jibin , Qu Jiaxiang , Yi Xian Ping , Graber Kelly , Huber Lu , Wang Xuejun , Gerdes A. Martin , Li Faqian
Published: August 2006

Recent progresses in signal transduction have revealed that β-catenin signaling controls embryonic development, tumorigenesis, cell shape, and polarity. The role of this pathway in myocyte shape regulation during cardiac hypertrophy and failure is, however, not clearly defined. Since homozygous knockout of β-catenin is embryonically lethal, we have deleted β-catenin genes specifically in the heart of adult mice by crossing loxP-flanked β-catenin mice with transgenic mice expressing tamoxifen-activated MerCreMer protein (MCM) driven by the α-myosin heavy chain promoter. Administration of tamoxifen to homozygous loxP-flanked β-catenin mice positive for MCM induces the deletion of β-catenin only in cardiomyocytes. Immunolabeling with β-catenin antibody demonstrates that 90% of cardiomyocytes completely lose their β-catenin expression but maintain normal rod-shaped morphology. The intercalated disk of cardiomyocytes lacking β-catenin is morphologically unremarkable with normal distribution of vinculin, N-cadherin, desmoplakin, ZO-1, connexin43, and α-, γ-, and p120 catenins. The expression level of these proteins, except that of γ-catenin, is also similar in tamoxifen-treated and control mice with both homozygous loxP-flanked β-catenin genes and the MCM transgene. Western blot analyses reveal that γ-catenin increases in the heart of β-catenin knockout mice compared with controls. Confocal microscopy also demonstrates that γ-catenin has significantly increased in the intercalated disk of cardiomyocytes lacking β-catenin. Echocardiographic data indicate that the knockout mice maintain normal ventricular geometry and cardiac function. The results suggest that upregulation of γ-catenin can compensate for the loss of β-catenin in cardiomyocytes to maintain normal cardiac structure and function.
Mechanisms of destabilization and early termination of spiral wave reentry in the ventricle by a class III antiarrhythmic agent, nifekalant
Authors: Yamazaki Masatoshi , Honjo Haruo , Nakagawa Harumichi , Ishiguro Yuko S. , Okuno Yusuke , Amino Mari , Sakuma Ichiro , Kamiya Kaichiro , Kodama Itsuo
Published: August 2006

Nifekalant (NF) is a novel class III antiarrhythmic agent that is effective in preventing life-threatening ventricular tachycardia/fibrillation (VT/VF). We investigated mechanisms of destabilization and early termination of spiral-type reentrant VT by NF in a two-dimensional subepicardial myocardial layer of Langendorff-perfused rabbit hearts ( n = 21) using a high-resolution optical action potential mapping system. During basic stimulation, NF (0.1 μM) caused uniform prolongation of action potential duration (APD) without affecting conduction velocity and an increase of APD restitution slope. VTs induced by direct current stimulation in the presence of NF were of shorter duration (VTs > 30 s: 2/54 NF vs. 19/93 control). During VTs in control (with visible rotors), the wave front chased its own tail with a certain distance (repolarized zone), and they seldom met each other. The average number of phase singularity (PS) points was 1.31 ± 0.14 per 665 ms ( n = 7). In the presence of NF, the wave front frequently encountered its own tail, causing a transient breakup of the spiral wave or sudden movement of the rotation center (spatial jump of PS). The average number of PS was increased to 1.63 ± 0.22 per 665 ms ( n = 7, P < 0.05) after NF. The mode of spontaneous termination of rotors in control was in most cases (9/10, 90.0%) the result of mutual annihilation of counterrotating wave fronts. With NF, rotors frequently terminated by wave front collision with the atrioventricular groove (12/19, 63.2%) or by trapping the spiral tip in a refractory zone (7/19, 36.8%). Destabilization and early termination of spiral wave reentry induced by NF are the result of a limited proportion of excitable tissue after modulation of repolarization.
Role of oxidative stress in PKC-δ upregulation and cardioprotection induced by chronic intermittent hypoxia
Authors: Kolář František , Ježková Jana , Balková Patricie , Břeh Jiří , Neckář Jan , Novák František , Nováková Olga , Tomášová Helena , Srbová Martina , Ošt’ádal Bohuslav , Wilhelm Jiří , Herget Jan
Published: August 2006

The aim was to determine whether increased oxidative stress during the adaptation to chronic intermittent hypoxia (CIH) plays a role in the induction of improved cardiac ischemic tolerance. Adult male Wistar rats were exposed to CIH in a hypobaric chamber (7,000 m, 8 h/day, 5 days/wk, 24–30 exposures). Half of the animals received antioxidant N-acetylcysteine (NAC; 100 mg/kg) daily before the exposure; the remaining rats received saline. Control rats were kept under normoxia and treated in a corresponding manner. One day after the last exposure (and/or NAC injection), anesthetized animals were subject to 20 min of coronary artery occlusion and 3 h of reperfusion for determination of infarct size. In parallel subgroups, biochemical analyses of the left ventricular myocardium were performed. Adaptation to CIH reduced infarct size from 56.7 ± 4.5% of the area at risk in the normoxic controls to 27.7 ± 4.9%. NAC treatment decreased the infarct size in the controls to 42.0 ± 3.4%, but it abolished the protection provided by CIH (to 41.1 ± 4.9%). CIH decreased the reduced-to-oxidized glutathione ratio and increased the relative amount of PKC isoform-δ in the particulate fraction; NAC prevented these effects. The expression of PKC-ε was decreased by CIH and not affected by NAC. Activities of superoxide dismutase, catalase, and glutathione peroxidase were affected by neither CIH nor NAC treatment. It is concluded that oxidative stress associated with CIH plays a role in the development of increased cardiac ischemic tolerance. The infarct size-limiting mechanism of CIH seems to involve the PKC-δ-dependent pathway but apparently not the increased capacity of major antioxidant enzymes.
Effects of an oral glucose tolerance test on the myogenic response in healthy individuals
Authors: Lott Mary E. J. , Hogeman Cynthia , Herr Michael , Gabbay Robert , Sinoway Lawrence I.
Published: August 2006

The myogenic response, the inherent ability of blood vessels to rapidly respond to changes in transmural pressure, is involved in local blood flow autoregulation. Animal studies suggest that both acute hyperglycemia and hyperinsulinemia may impair myogenic vasoconstriction. The purpose of this study was to examine the effects of an oral glucose load on brachial mean blood velocity (MBV) during increases in forearm transmural pressure in humans. Eight healthy men and women (38 ± 5 yr) underwent an oral glucose tolerance test (OGTT). MBV (in cm/s; Doppler ultrasound) responses to a rise in forearm transmural pressure (arm tank suction, −50 mmHg) were studied before and every 30 min for 120 min during the OGTT. Before the start of the OGTT, MBV was lower than baseline values 30 and 60 s after the application of negative pressure. This suggests that myogenic constriction was present. During the OGTT, blood glucose rose from 88 ± 2 to 120 ± 6 mg/dl ( P < 0.05) and insulin rose from 14 ± 1 to 101 ± 32 μU/ml ( P < 0.05). Glucose loading attenuated the reduction in MBV with arm suction (Δ−0.73 ± 0.14 vs. Δ−1.67 ± 0.43 cm/s and Δ−1.07 ± 0.14 vs. Δ−2.38 ± 0.54 cm/s, respectively, during 30 and 60 s of suction postglucose compared with preglucose values; all P < 0.05). We observed no such time effect for myogenic responses during a sham OGTT. In an additional 5 subjects, glucose loading had no effect on brachial diameters with the application of negative pressure. Oral glucose loading leads to attenuated myogenic vasoconstriction in healthy individuals. The role that this diminished postglucose reactivity plays in mediating postprandial hypotension and/or orthostasis needs to be further explored.
Antenatal inflammation induced TGF-β1 but suppressed CTGF in preterm lungs
Authors: Kunzmann Steffen , Speer Christian P. , Jobe Alan H. , Kramer Boris W.
Published: August 2006

Chorioamnionitis is frequently associated with preterm birth and increases the risk of adverse outcomes such as bronchopulmonary dysplasia (BPD). Transforming growth factor (TGF)-β1 is a key regulator of lung development, airway remodeling, lung fibrosis, and regulation of inflammation, and all these processes contribute to the development of BPD. Connective tissue growth factor (CTGF) is a downstream mediator of some of the profibrotic effects of TGF-β1, vascular remodeling, and angiogenesis. TGF-β1-induced CTGF expression can be blocked by TNF-α. We asked whether chorioamnionitis-associated antenatal inflammation would regulate TGF-β1, the TGF-β1 signaling pathway, and CTGF in preterm lamb lungs. Fetal sheep were exposed to 4 mg of intra-amniotic endotoxin or saline for 5 h, 24 h, 72 h, or 7 days before preterm delivery at 125 days gestation (full term = 150 days). Intra-amniotic endotoxin increased lung TGF-β1 mRNA and protein expression. Elevated TGF-β1 levels were associated with TGF-β1-induced phosphorylation of Smad2. CTGF was selectively expressed in lung endothelial cells in control lungs, and intra-amniotic endotoxin caused CTGF expression to decrease to 30% of control values and TNF-α protein to increase. The antenatal inflammation-induced TGF-β1 expression and Smad signaling in the fetal lamb lung may contribute to impaired lung alveolarization and reduced lung inflammation. Decreased CTGF expression may inhibit vascular development or remodeling and limit lung fibrosis during remodeling. These effects may contribute to the impaired alveolar and pulmonary vascular development that is the hallmark of the new form of BPD.
Pulmonary vasodilation by acetazolamide during hypoxia is unrelated to carbonic anhydrase inhibition
Authors: Höhne Claudia , Pickerodt Philipp A. , Francis Roland C. , Boemke Willehad , Swenson Erik R.
Published: August 2006

Acute hypoxic pulmonary vasoconstriction can be inhibited by high doses of the carbonic anhydrase inhibitor acetazolamide. This study aimed to determine whether acetazolamide is effective at dosing relevant to human use at high altitude and to investigate whether its efficacy against hypoxic pulmonary vasoconstriction is dependent on carbonic anhydrase inhibition by testing other potent heterocyclic sulfonamide carbonic anhydrase inhibitors. Six conscious dogs were studied in five protocols: 1) controls, 2) low-dose intravenous acetazolamide (2 mg·kg−1·h−1), 3) oral acetazolamide (5 mg/kg), 4) benzolamide, a membrane-impermeant inhibitor, and 5) ethoxzolamide, a membrane-permeant inhibitor. In all protocols, unanesthetized dogs breathed spontaneously during the first hour (normoxia) and then breathed 9–10% O2 for the next 2 h. Arterial oxygen tension ranged between 35 and 39 mmHg during hypoxia in all protocols. In controls, mean pulmonary artery pressure increased by 8 mmHg and pulmonary vascular resistance by 200 dyn·s·cm−5 ( P <0.05). With intravenous acetazolamide, mean pulmonary artery pressure and pulmonary vascular resistance remained unchanged during hypoxia. With oral acetazolamide, mean pulmonary artery pressure increased by 5 mmHg ( P < 0.05), but pulmonary vascular resistance did not change during hypoxia. With benzolamide and ethoxzolamide, mean pulmonary artery pressure increased by 6–7 mmHg and pulmonary vascular resistance by 150–200 dyn·s·cm−5 during hypoxia ( P < 0.05). Low-dose acetazolamide is effective against acute hypoxic pulmonary vasoconstriction in vivo. The lack of effect with two other potent carbonic anhydrase inhibitors suggests that carbonic anhydrase is not involved in the mediation of hypoxic pulmonary vasoconstriction and that acetazolamide acts on a different receptor or channel.
Alterations in zinc homeostasis underlie endothelial cell death induced by oxidative stress from acute exposure to hydrogen peroxide
Authors: Wiseman Dean A. , Wells Sandra M. , Hubbard Maryann , Welker Jonathan E. , Black Stephen M.
Published: August 2006

Oxidative stress has been associated with multiple pathologies and disease states, including those involving the cardiovascular system. Previously, we showed that pulmonary artery endothelial cells (PAECs) undergo apoptosis after acute exposure to H2O2. However, the underlying mechanisms regulating this process remain unclear. Because of the prevalence of H2O2in normal physiological processes and apparent loss of regulation in disease states, the purpose of this study was to develop a more complete understanding of H2O2-mediated adverse effects on endothelial cell survival. Acute exposure of PAECs to H2O2caused a dose-dependent increase in cellular release of lactate dehydrogenase and a significant increase in production of superoxide ions, which appear to be generated within the mitochondria, as well as a significant loss of mitochondrial membrane potential and activity. Subsequent to the loss of mitochondrial membrane potential, PAECs exhibited significant caspase activation and apoptotic nuclei. We also observed a significant increase in intracellular free Zn2+after bolus exposure to H2O2. To determine whether this increase in Zn2+was involved in the apoptotic pathway induced by acute H2O2exposure, we developed an adenoviral construct for overexpression of the Zn2+-binding protein metallothionein-1. Our data indicate that chelating Zn2+, either pharmacologically with N,N,N′, N-tetrakis(2-pyridylmethyl)ethylene diamine or by overexpression of the Zn2+-binding protein metallothionein-1, in PAECs conferred significant protection from induction of apoptosis and cell death associated with the effects of acute H2O2exposure. Our results show that the acute toxicity profile of H2O2can be attributed, at least in part, to liberation of Zn2+within PAECs. We speculate that regulation of Zn2+levels may represent a potential therapeutic target for cardiovascular disease associated with acute oxidative stress.
Age and growth of the Patagonian lizard Phymaturus patagonicus
Authors: Piantoni Carla , Cussac Victor , Ibargüengoytía Nora
Published: August 2006

The growth dynamics of Phymaturus patagonicus, a diurnal, herbivorous and viviparous lizard from the Argentinean Patagonian steppe, was studied using eight juveniles (two born in the laboratory), 11 adult females and eight adult males. Histological cross sections of femoral bones were analysed to determine if individuals show osseous growth marks and if these marks provide useful age estimates. Individual ages were assessed after estimating the reabsorbed rings in relation to snout-vent length. There was a strong relationship between body length and estimated age, modelled by a sigmoidal curve. Sexual maturity was found to be reached at seven years in females and nine in males and the maximum life span was estimated to be 16 years. No difference in body length was observed between the same-age females and males. We postulate that severe environments such as the north Patagonian steppe play a significant role in the selection of not only modes of reproduction but also delayed maturity and prolonged reproductive cycles, a combination that results in low fecundity.
Marbled salamanders (Ambystoma opacum) choose low elevation nest sites when cover availability is controlled
Authors: Scott David , Croshaw Dean
Published: August 2006

Nest site selection is an important part of adult reproductive behavior because growth and survival of young are often affected by the local environment. In terrestrially nesting marbled salamanders, nest elevation is likely important to reproductive success because it is directly related to the time of hatching. We tested the hypothesis that females choose nest sites based on elevation and its correlates by controlling the availability of nesting cover, a potentially important factor in nest site selection which often covaries with elevation. Breeding adults were confined to field enclosures in which natural nesting cover had been removed and replaced with equal proportions of artificial cover in each of three elevation zones. In four enclosures that spanned from lowest to highest areas of a wetland breeding site, females used artificial nesting cover most frequently at low elevations. These results contrast with other studies in which intermediate elevations had highest nest densities, but are consistent with a conceptual model in which opposing selective forces result in locally adapted nest site selection.
Hard Wired for Negative News? Gender Differences in Processing Broadcast News
Authors: Grabe Maria Elizabeth , Kamhawi Rasha
Published: August 2006

The experimental study reported here investigated information processing of broadcast news at the intersection of audience gender (male versus female) and message valence (positive, negative, and ambiguous). Both audio and video dimensions of stimuli were manipulated to create the three valence frames. The data produced interactions between gender and message valence for self-reported arousal, as well as recognition memory and comprehension of news content. In particular, male viewers are associated with a negativity bias, reporting the highest arousal levels and producing the best recognition memory and comprehension scores for negatively valenced messages. Women, in contrast, show signs of an avoidance response to negatively framed news, rating positively valenced stories as more arousing as well as processing such messages more effectively than negatively framed messages. Within the information-processing paradigm these findings suggest that the gender variable deserves more research attention. The results also have implications for journalism practitioners.
Information Exchange With Shared Databases as a Social Dilemma
Authors: Cress Ulrike , Kimmerle Joachim , Hesse Friedrich W.
Published: August 2006

When group members exchange information via shared databases people are often reluctant to contribute information they possess. This is explained by the fact that this kind of information exchange represents a social dilemma. This article applies critical concepts of dilemma theory to the interpretation of database information exchange as a social dilemma and tests their effects experimentally. A prestudy with the experimental task ensures that people perceive database information exchange as a social dilemma, and two experiments investigate three factors influencing this dilemma: (a) a person’s meta-knowledge about the importance of his information for the other group members, (b) a use-related bonus system that rewards contribution of important information, and (c) costs incurred by the contribution of important or less important information. As dependent variables people’s contribution behavior as well as their subjective perception of the dilemma structure are considered. The results show that metaknowledge enhances the quality of contributions, especially in combination with a use-related bonus system, whereas increased contribution costs influence the contribution behavior negatively.
Early Adolescent Delinquency
Authors: Sullivan Christopher J.
Published: August 2006

Research has demonstrated a relationship between various types of emotional and behavioral problems and delinquency. Still, some aspects of this relationship are not as clear, particularly as pertains to emotional and behavioral problems and delinquent behavior across a broader range of time in the context of other key risk and protective factors. A three-pronged analytic approach examined the effects and function of key covariates on delinquent behavior in early adolescence. Childhood emotional and behavioral problems had a consistent, albeit modest, effect on delinquent behavior in early adolescence. Peer influence was found to be the strongest predictor of delinquent behavior, but family environment demonstrated a protective effect nonetheless. Implications for future research, theoretical elaboration, and policy initiatives are discussed.
Violence from Within the Reform School
Authors: Honkatukia Päivi , Nyqvist Leo , Pösö Tarja
Published: August 2006

This article examines young people's talk of violence to highlight the meanings of violence. Violence is approached as a fluid concept with multiple meanings. The empirical data consist of 15 focus group interviews of young people (38 young people between 12 and 17 years of age) in two Finnish reform schools carried out by two interviewers in each session. The interviews looked at the young residents' views on violence in general and on the reform schools in particular. The analysis focuses on the narrative means that the young people employed to describe violence: violence either as an instrumental means or as a form of expression. The collective nature of violence was emphasized. The results suggest that it is important to identify the multiple meanings assigned to violence for the needs of social and criminal policy and of research.
Exploring Moral Situations, Moral Emotions, and Moral Self as Predictors of Juvenile Delinquents' Global Self-Esteem
Authors: Forney William Scott , Crutsinger Christy , Forney Judith Cardona
Published: August 2006

Shoplifting or theft, offenders'immature or mature emotional responses to shoplifting, and moral predictors of global self-esteem were explored. Phase 1 classified moral emotions by shoplifting situations. Phase 2 predicted effects of moral situations on moral emotions and moral self and their overall effect on global self-esteem. Implications address moral education and shoplifting.
Treatment with HMGB1 inhibitors diminishes CTL-induced liver disease in HBV transgenic mice
Authors: Sitia Giovanni , Iannacone Matteo , Müller Susanne , Bianchi Marco E , Guidotti Luca G
Published: August 2006

Using hepatitis B virus (HBV) transgenic mice as recipients of virus-specific cytotoxic T lymphocytes (CTLs), we recently showed that polymorphonuclear neutrophils (PMNs) and the matrix-degrading metalloproteinases (MMPs) they produce are necessary for the intrahepatic recruitment of antigen nonspecific mononuclear cells that amplify the liver damage initiated by the CTLs. We now report that the high-mobility group box 1 protein (HMGB1) is also involved in this process. Transfer of CTLs in HBV transgenic mice induces the translocation of HMGB1 from the nucleus to the cytoplasm of hepatocytes surrounding CTL-containing necroinflammatory liver foci, without significant net synthesis of HMGB1. Treatment of CTL-injected HBV transgenic mice with either recombinant Box-A or glycyrrhizin, two functional inhibitors of extracellular HMGB1, significantly decreases the intrahepatic recruitment of PMNs and all other inflammatory cells, in the face of intact homing of virus-specific CTLs into the liver. The inhibition of PMN chemoattraction explains the mode of action of glycyrrhizin, which has long been used in Japan for the treatment of hepatitis, and suggests that new and more potent inhibitors of HMGB1 may be useful for the treatment of patients chronically infected with HBV.
Advances in macrophage and dendritic cell biology in HIV-1 infection stress key understudied areas in infection, pathogenesis, and analysis of viral reservoirs
Authors: Montaner Luis J , Crowe Suzanne M , Aquaro Stefano , Perno Carlo-Federico , Stevenson Mario , Collman Ronald G
Published: August 2006

The continued quest to intervene in HIV-1 infection by halting transmission, suppressing replication, or eradicating disease in infected subjects stresses the significance of dendritic cell and macrophage biology as early and persistent players in the relationship between infection and disease. As highlighted by new data and presentations at the Sixth International Workshop on HIV and Cells of Macrophage/Dendritic Lineage and Other Reservoirs, a greater emphasis is currently underway in studying the potential of targeting these cell types by intervention early in infection, better defining viral phenotypes and entry mechanisms with a more precise nomenclature system, identifying new, intrinsic cellular factors that may restrict infection within these cell types, and pursuing novel roles for macrophage activation and trafficking. Other key areas include examination of these cells as sources of viral persistence in patients, their roles in coinfection, and their metabolic function in HIV pathogenesis and drug toxicity. This issue of JLB contains reviews and original research reports from the workshop, which highlight new findings, current research questions, and key areas in need of future investigation as a result of their significance to HIV prevention and pathogenesis.
Practical Means for Determination of the Tensile Behavior of Ultra-High Performance Concrete
Authors: Graybeal BA
Published: August 2006

Ultra-high performance concrete exhibits sufficient tensile strength and tensile toughness that structurally efficient use of these concretes demands that the tensile capabilities be utilized. A means of determining the tensile properties of UHPC is essential to the expanded use of this advanced construction material. However, no simple, practical test currently exists to determine or verify these properties in a production environment. The ASTM C 496 splitting tensile test method presents a starting point for the development of a practical test procedure, as this test method both is comparatively easy to perform and is well regarded in terms of its ability to create a uniform tensile stress field within a concrete sample. This paper presents an adaptation of this test method that allows for quantitative determination of the tensile cracking strength of UHPC and for qualitative verification of the post-cracking tensile behaviors.
Stress Intensity Formulas for Three-dimensional Cracks in the Vicinity of an Interface
Authors: Noda N-A , Liang B
Published: August 2006

In this study, stress intensity formulas are considered in terms of the square root of area parameter to evaluate arbitrary shaped defects or cracks in the vicinity of an interface. Here “area” is the projected area of the defect or crack. Stress intensity factors for an elliptical crack parallel to a bimaterial interface are considered with varying the distance, aspect ratio of the crack, and combinations of material's elastic constants. Also, stress intensity factors of an interface crack and a crack in a functionally graded material are investigated. Then, it is found that the maximum stress intensity factors normalized by the square root of area are always insensitive to the crack aspect ratio. They are given in a form of formulas useful for engineering applications.
Comparison of Escherichia coli, Total Coliform, and Fecal Coliform Populations as Indicators of Wastewater Treatment Efficiency
Authors: Elmund G. Keith , Allen Martin J. , Rice Eugene W.
Published: August 2006

Escherichia coli, total coliform, and fecal coliform population data were collected from two wastewater treatment facilities, a subsurface flow artificial wetlands, and a receiving stream. Results are presented from individual wastewater treatment process streams, final effluent, and river sites upstream and downstream of the treatment facilities. The QuantiTray technique with 4‐methylumbelliferyl‐β‐glucuronide‐based Colilert media was an effective method for quantifying E. coli and total coliform populations in these waters. Thermotolerant Klebsiella pneumoniae present in the effluent from one treatment facility interfered with recovery of fecal coliforms on m‐FC media using the delayed‐incubation membrane filtration technique; Klebsiella interference was not observed in the enumeration of E. coli by the QuantiTray technique. Both stream standards and discharge permits can be revised to apply E. coli as the indicator of fecal contamination. The results support development of E. coli‐based effluent and stream standards to protect public health.
An Analysis of Bubble Formation Using Microporous Hollow Fiber Membranes
Authors: Semmens M.J. , Gulliver John S. , Anderson Anita
Published: August 2006

A study was conducted to characterize bubble formation behavior of pressurized microporous hollow fiber membranes with water flow normal to the fiber axis. The influence of operating conditions such as water velocity (0.07 to 0.6 m/s), gas pressure (275 to 380 kPa), and gas fluxes (0.001 to 0.02 m/s) on bubble formation behavior was examined. Within these operating conditions, bubbles with a diameter smaller than a 100 μm were formed at the membrane surface. Coalescence occurred close to the membrane, which resulted in bubble diameters of 100 to 500 μm above the fiber. Bubble diameters increased with increasing gas flow rate and decreasing water velocity. These effects are expected as they both lead to increased local bubble density and rates of coalescence. Bubble formation behavior of the membrane was predicted well by an empirical equation determined for a single orifice by Ito and Hirata, (1980).
Electroosmotically Enhanced Sludge Pressure Filtration
Authors: Gingerich Ilene , Neufeld Ronald D. , Thomas Todd A.
Published: August 2006

Wastewater sludge is routinely dewatered to lower the cost of transportation and disposal. Dewatering is achieved via vacuum filtration, centrifugation, sand beds, and belt filter presses. Electroosmosis, the movement of water in the influence of a direct‐current (dc) electric field, has been used since the 1930s to dewater soil for construction purposes. This study examines dewatering anaerobically and aerobically digested municipal wastewater solids with applied direct pressure and constant voltage direct current. A pressure filtration apparatus, consisting of a piston and drain plate made of conductive material encased in a body of nonconductive material, was used to apply constant pressure and constant voltage (variable current) during the experiments. Three experimental series were conducted evaluating the effect of polymer dosage and voltage on the final cake total solids; the relationship among pressure, voltage, time, and final cake total solids; and the relationship among initial feed solids and final cake total solids after electroosmotic filtration. Results show that final cake solids were increased to as much as 50% with 60 V dc applied. Final cake solids may be enhanced by increasing pressure, voltage, or time, and additional water may be removed from a conventionally dewatered cake by further application of dc voltage.
Investigation of the effects of nonconventional beam geometries in laser surface treatment of ceramics: Experimental analysis
Authors: Triantafyllidis D. , Li L. , Stott F. H.
Published: August 2006

Laser surface treatment of ceramics by melting and resolidification generally leads to the formation of fully densified and homogeneous surfaces, with enhanced mechanical and physical properties. A common problem associated with the process is the formation of thermally induced cracks on solidification. This, however, can be eliminated by controlling the cooling rates and thermal gradients during processing. The technique of scanning the laser beam at relatively slow speeds to modify the thermal shock conditions to which the surface is subjected, has been successfully applied to the development of crack-free surfaces in Al2O3-based refractory ceramics. The relatively slow speed, however, limits the practicability of the technique. Novel work on the effects of various nonconventional beam geometries on cooling rates and, hence, on interaction times and processing speeds, during laser surface treatment of ceramics has been carried out. A commercial finite element analysis package was used to simulate the material-beam interaction conditions for various beam geometries, including rectangular, line, triangular, pi, and rhomboid. Extensive experimental work has verified the theoretical finite element analysis results, concentrating on the pi and rhomboid beam geometries. The time-temperature histories of the aforementioned geometries were measured in-process, and compared with the modeling results; this confirmed that the processing speed for the rhomboid geometry had to be increased by a factor of about 5 and that for the pi geometry by a factor of about 2.5 compared to the standard circular beam geometry to produce similar cooling rates. The characteristics of the surfaces treated with the pi and the rhomboid beam geometries at these speeds confirmed the formation of crack-free, fully densified and homogeneous surfaces. The treated zones consisted of a biphasic microstructure, including a crystalline Al2O3-Cr2O3 solid solution and aluminosilicate glass. These features, as well as the mechanical properties, were similar to those of the surfaces treated with the conventional circular beam geometry.
The influence of joint gap on the strength of hybrid Nd:yttrium-aluminum-garnet laser-metal inert gas welds
Authors: Wouters M. , Powell J. , Kaplan A. F. H.
Published: August 2006

This article presents the results of an experimental and theoretical analysis of the effect of joint gap on the strength of hybrid laser-metal inert gas welds. The welds were of the partial penetration butt type with various joint gaps but identical weld penetration. Impact testing established that a zero gap gave a weak weld because the weld geometry contained the equivalent of a sharp crack where the unwelded parts met each other. A small gap between the workpieces improved the weld impact strength as the sharp crack effect became dissipated. Further increases in gap width resulted in a weakening of the joint and this is the subject of a discussion on joint gap optimization.
Femtosecond laser bulk micromachining of microfluid channels in poly(methylmethacrylate)
Authors: Farson Dave F. , Choi Hae Woon , Lu Chunmeng , Lee L. James
Published: August 2006

Internal channels in a polymer are widely used in biotechnology applications such as DNA stretching and in devices such as micrototal analysis systems and lab on a chip systems. For manufacturing prototype devices, femtosecond pulsed laser energy has been used to implement a convenient direct write bulk-machining process in glass. In this technique, the laser beam is focused inside of a transparent material, resulting in the ablation of an internal channel. Initial experiments for internal channel fabrication in a poly(methylmethacrylate) (PMMA) polymer revealed a significant problem with clogging of channels by debris and rough, fractured channel walls. In this article, we describe a new method to fabricate internal channels in PMMA using femtosecond pulsed laser energy and a gas-assisted material removal concept. Relatively smooth channels with a minimum diameter of 2 μm, a maximum diameter of 20 μm, and a maximum length of 10 mm were achieved with this technique.