bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of binocular vision in walking
Authors: HAYHOE MARY , GILLAM BARBARA , CHAJKA KELLY , VECELLIO ELIA
Published: January 2009

Despite the extensive investigation of binocular and stereoscopic vision, relatively little is known about its importance in natural visually guided behavior. In this paper, we explored the role of binocular vision when walking over and around obstacles. We monitored eye position during the task as an indicator of the difference between monocular and binocular performances. We found that binocular vision clearly facilitates walking performance. Walkers were slowed by about 10% in monocular vision and raised their foot higher when stepping over obstacles. Although the location and sequence of the fixations did not change in monocular vision, the timing of the fixations relative to the actions was different. Subjects spent proportionately more time fixating the obstacles and fixated longer while guiding foot placement near an obstacle. The data are consistent with greater uncertainty in monocular vision, leading to a greater reliance on feedback in the control of the movements.
The diet of post-breeding Antarctic shagsPhalacrocorax bransfieldensisat the Danco Coast, Antarctic Peninsula
Authors: Casaux R. , Baroni A. , Ramón A. , Bertolin M. , Di Prinzio C.Y.
Published: January 2009

The diet of post-breeding Antarctic shagsPhalacrocorax bransfieldensiswas investigated at four colonies at the Danco Coast, Antarctic Peninsula, by the analysis of 399 pellets (regurgitated casts) collected during February and March 1998 and 2000. Overall, demersal-benthic fish were the most frequent and important prey at all the colonies sampled, followed by octopods and gastropods. Amongst the fish,Notothenia coriicepsandGobionotothen gibberifronswere the main prey in all of the sampling sites in both seasons. The composition of the diet of post-breeding shags differed from that observed in the previous breeding season. Post-breeders preyed on the same fish species consumed by breeders, although in different proportions and on larger specimens. The information provided here differs from that reported for post-breeding individuals belonging to other shag species and also for post-breeding Antarctic shags. Our results, as well as the differences with previous studies, are discussed in relation to differences in prey availability among localities and to the use of alternative foraging grounds at the end of the breeding period.
Wunschvorstellungen vom Lebensende. Ergebnisse einer Befragung von Pflegepersonen und Menschen in Pensionsvorbereitung zu ihren Präferenzen für bestimmte «dying trajectories»
Authors: Tobler  , Scholian
Published: January 2009

Anhand von vier Modellkurven («dying trajectories») befragten wir Mitarbeitende von Pflegeinstitutionen sowie Teilnehmende von Pensionsvorbereitungskursen nach ihren Wunschvorstellungen vom Lebensende (n = 159). Frauen wünschten durchschnittlich 85.6 Jahre und Männer 83.8 Jahre alt zu werden. 43% der Befragten sprachen sich für einen plötzlichen Tod aus mit der häufigsten Begründung «kein Leiden», 50% für einen Tod innerhalb weniger Wochen bis Monate mit der Begründung «Abschied nehmen». Für ein Leben ohne Pflegebedürftigkeit und Abhängigkeit würden 34% der Befragten mindestens sechs und 61% mindestens zwei Lebensjahre einsetzen, während 14% überhaupt keine Lebenszeit herzugeben bereit wären.
Therapie des Morbus Crohn
Authors: Vavricka  , Rogler
Published: January 2009

Die Therapie des Morbus Crohn richtet sich nach der Krankheitsaktivität. So werden unterschiedliche Therapiekonzepte in den verschiedenen Krankheitsphasen (aktiver Schub, chronisch aktive Erkrankung und Remission) angewendet. Die folgende Übersicht soll die wichtigsten Konzepte kurz vorstellen.
Schilddrüsenknoten – Klinik und Differentialdiagnose
Authors: Giovanella
Published: January 2009

Schilddrüsenknoten sind häufig, und oft sind sie gutartig. Die Prävalenz liegt zwischen 3–7% (Palpation) und 50% (Sonographie). 5–10% der Schilddrüsenknoten sind maligne. Die Schilddrüsensonographie eignet sich nicht als Screening-Untersuchung, trotzdem sollten alle Patienten mit einem palpablen Knoten sonographiert werden. Ergibt der Ultraschall verdächtige Befunde oder bestehen klinische Risikofaktoren, sollte eine sonographisch geführte Feinnadelpunktion vorgenommen werden. Die Schilddrüsenszintigraphie erlaubt die Identifikation von (benignen) funktionellen Knoten bei tiefem oder supprimiertem TSH.
Cytochrome P450 oxidoreductase participates in nitric oxide consumption by rat brain
Authors: Hall Catherine N. , Keynes Robert G. , Garthwaite John
Published: January 2009

In low nanomolar concentrations, NO (nitric oxide) functions as a transmitter in brain and other tissues, whereas near-micromolar NO concentrations are associated with toxicity and cell death. Control of the NO concentration, therefore, is critical for proper brain function, but, although its synthesis pathway is well-characterized, the major route of breakdown of NO in brain is unclear. Previous observations indicate that brain cells actively consume NO at a high rate. The mechanism of this consumption was pursued in the present study. NO consumption by a preparation of central glial cells was abolished by cell lysis and recovered by addition of NADPH. NADPH-dependent consumption of NO localized to cell membranes and was inhibited by proteinase K, indicating the involvement of a membrane-bound protein. Purification of this activity yielded CYPOR (cytochrome P450 oxidoreductase). Antibodies against CYPOR inhibited NO consumption by brain membranes and the amount of CYPOR in several cell types correlated with their rate of NO consumption. NO was also consumed by purified CYPOR but this activity was found to depend on the presence of the vitamin E analogue Trolox (6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid), included in the buffer as a precaution against inadvertent NO consumption by lipid peroxidation. In contrast, NO consumption by brain membranes was independent of Trolox. Hence, it appears that, during the purification process, CYPOR becomes separated from a partner needed for NO consumption. Cytochrome P450 inhibitors inhibited NO consumption by brain membranes, making these proteins likely candidates.
Contemporary Trends and Issues in it Adoption and Diffusion Research
Authors: Williams Michael D , Dwivedi Yogesh K , Lal Banita , Schwarz Andrew
Published: January 2009

The high level of investigative activity to date into information systems and information technology acceptance and diffusion has witnessed the use of a wide range of exploratory techniques, examining many different systems and technologies in countless different contexts and geographical locations. The aim of this paper is to provide a comprehensive and systematic review of the literature pertaining to such adoption and diffusion issues in order to observe trends, ascertain the current ‘state of play’, and to highlight promising lines of inquiry including those lacking investigative activity or simply being in need of renewed interest. Previous research activity was analysed along a number dimensions including units of analysis, research paradigms, methodologies, and methods, theories and theoretical constructs, and technologies/contexts examined. Information on these and other variables was extracted during an examination of 345 papers on innovation adoption, acceptance and diffusion appearing in 19 peer-reviewed journals between 1985 and 2007. Findings suggest that the positivist paradigm, empirical and quantitative research, the survey method and Technology Acceptance Model theory (and its associated constructs) were predominantly used in the body of work examined, revealing clear opportunities for researchers to make original contributions by making greater use of the theoretical and methodological variety available to them, and consequently reducing the risk of research in the area moving toward overall homogeneity.
Reversible binding and rapid diffusion of proteins in complex with inositol lipids serves to coordinate free movement with spatial information
Authors: Hammond Gerald R.V. , Sim Yirong , Lagnado Leon , Irvine Robin F.
Published: January 2009

Polyphosphoinositol lipids convey spatial information partly by their interactions with cellular proteins within defined domains. However, these interactions are prevented when the lipids' head groups are masked by the recruitment of cytosolic effector proteins, whereas these effectors must also have sufficient mobility to maximize functional interactions. To investigate quantitatively how these conflicting functional needs are optimized, we used different fluorescence recovery after photobleaching techniques to investigate inositol lipid–effector protein kinetics in terms of the real-time dissociation from, and diffusion within, the plasma membrane. We find that the protein–lipid complexes retain a relatively rapid (∼0.1–1 µm2/s) diffusion coefficient in the membrane, likely dominated by protein–protein interactions, but the limited time scale (seconds) of these complexes, dictated principally by lipid–protein interactions, limits their range of action to a few microns. Moreover, our data reveal that GAP1IP4BP, a protein that binds PtdIns(4,5)P2 and PtdIns(3,4,5)P3 in vitro with similar affinity, is able to “read” PtdIns(3,4,5)P3 signals in terms of an elongated residence time at the membrane.
Differential roles of migratory and resident DCs in T cell priming after mucosal or skin HSV-1 infection
Authors: Lee Heung Kyu , Zamora Melodie , Linehan Melissa M. , Iijima Norifumi , Gonzalez David , Haberman Ann , Iwasaki Akiko
Published: January 2009

Although mucosal surfaces represent the main portal of entry for pathogens, the mechanism of antigen presentation by dendritic cells (DCs) that patrol various mucosal tissues remains unclear. Instead, much effort has focused on the understanding of initiation of immune responses generated against antigens delivered by injection. We examined the contributions of migratory versus lymph node–resident DC populations in antigen presentation to CD4 and CD8 T cells after needle injection, epicutaneous infection, or vaginal mucosal herpes simplex virus (HSV) 1 infection. We show that upon needle injection, HSV-1 became lymph-borne and was rapidly presented by lymph node–resident DCs to CD4 and CD8 T cells. In contrast, after vaginal HSV-1 infection, antigens were largely presented by tissue-derived migrant DCs with delayed kinetics. In addition, migrant DCs made more frequent contact with HSV-specific T cells after vaginal infection compared with epicutaneous infection. Thus, both migrant and resident DCs play an important role in priming CD8 and CD4 T cell responses, and their relative importance depends on the mode of infection in vivo.
Differential compaction due to the irregular topology of a diagenetic reaction boundary: a new mechanism for the formation of polygonal faults
Authors: Davies R. J. , Ireland M. T. , Cartwright J. A.
Published: January 2009

We propose a new mechanism for the formation of some polygonal fault arrays. Seismically imaged opal‐A (biogenic silica) to opal‐CT (cristobalite and tridymite) diagenetic boundaries from two regions offshore of Norway have developed regular wavelength patterns. The pattern consists of cell‐shaped elevations that are 200–2600 m wide and up to 200 m high, separated by troughs. The cells represent regions that undergo diagenesis at shallower burial depths, earlier than adjacent areas. The chemical change leads to mechanical compaction and porosity reduction; therefore subsidence occurs above the cells in the overburden. Roughly circular depressions form above the cells, and a network of folds form above inter‐cell areas. Networks of normal faults form on the crests and margins of the folds as a result of flexure during the folding. The progressive lateral growth of the cells causes the depressions to widen and intervening folds to narrow resulting in new differential compaction‐induced faults to form with variable strike orientations. Lateral and vertical growth of cells leads to cells conjoining and the re‐establishment of a uniform planar reaction boundary. This novel but simple mechanism can explain some polygonal fault arrays that form above opal‐A to opal‐CT reaction boundaries and in these settings the mechanism should be considered in addition to syneresis, density inversion or low coefficients of residual friction which are the most commonly cited drivers for polygonal fault systems.
Reversibility of symptomatic peripheral neuropathy with bortezomib in the phase III APEX trial in relapsed multiple myeloma: impact of a dose‐modification guideline
Authors: Richardson Paul G. , Sonneveld Pieter , Schuster Michael W. , Stadtmauer Edward A. , Facon Thierry , Harousseau Jean‐Luc , Ben‐Yehuda Dina , Lonial Sagar , Goldschmidt Hartmut , Reece Donna , Bladé Joan , Boccadoro Mario , Cavenagh Jamie D. , Boral Anthony L. , Esseltine Dixie‐Lee , Wen Patrick Y. , Amato Anthony A. , Anderson Kenneth C. , San Miguel Jesus
Published: January 2009

The frequency, characteristics and reversibility of bortezomib‐associated peripheral neuropathy were evaluated in the phase III APEX (Assessment of Proteasome Inhibition for Extending Remissions) trial in patients with relapsed myeloma, and the impact of a dose‐modification guideline on peripheral neuropathy severity and reversibility was assessed. Patients received bortezomib 1·3 mg/m2 (days 1, 4, 8, 11, eight 21‐d cycles, then days 1, 8, 15, 22, three 35‐d cycles); bortezomib was held, dose‐reduced or discontinued depending on peripheral neuropathy severity, according to a protocol‐specified dose‐modification guideline. Overall, 124/331 patients (37%) had treatment‐emergent peripheral neuropathy, including 30 (9%) with grade ≥3; incidence and severity were not affected by age, number/type of prior therapies, baseline glycosylated haemoglobin level, or diabetes history. Grade ≥3 incidence appeared lower versus phase II trials (13%) that did not specifically provide dose‐modification guidelines. Of patients with grade ≥2 peripheral neuropathy, 58/91 (64%) experienced improvement or resolution to baseline at a median of 110 d, including 49/72 (68%) who had dose modification versus 9/19 (47%) who did not. Efficacy did not appear adversely affected by dose modification for grade ≥2 peripheral neuropathy. Bortezomib‐associated peripheral neuropathy is manageable and reversible in most patients with relapsed myeloma. Dose modification using a specific guideline improves peripheral neuropathy management without adversely affecting outcome.
Lack of nidogen‐2 increases blood pressure, glomerular and tubulointerstitial damage in DOCA‐salt hypertension
Authors: Amann K. , Haas C. S. , Zeiler G. A. , Benz K. , Bader B. L. , Hartner A. , Hilgers K. F.
Published: January 2009

Background  Nidogen‐2, an extracellular matrix protein, is ubiquitous in renal basement membranes linking the laminin and collagen IV networks. Nidogen‐2‐deficient (nidogen‐2−/–) mice do not exhibit a phenotype, and renal basement membranes appear normal. The functional role of nidogen‐2 in the adult kidney under pathological conditions however remains unclear. We tested the hypothesis that nidogen‐2 mediated cell‐matrix interactions are important to maintain glomerular integrity and structure in renal hyperperfusion and hypertension.

Materials and methods  Two weeks after unilateral nephrectomy (UNX), desoxycorticosterone (DOCA)‐salt hypertension was induced in nidogen‐2−/– mice and their wild type littermates for 6 weeks. Renal damage was assessed by means of semiquantitative scoring, morphometric analysis, immunohistochemistry and measurement of serum creatinine and albumin excretion.

Results  UNX alone resulted in a very mild increase in renal damage in nidogen‐2−/– mice compared to wild type animals. Following DOCA‐salt treatment, blood pressure, serum creatinine and albumin excretion were significantly higher in nidogen‐2−/– than in wild type mice. In addition, nidogen‐2−/– mice showed increased mesangial cell hyperplasia and matrix expansion with higher expression of fibronectin and its receptor α8 integrin. Glomerular capillaries were significantly reduced in size and number.

Conclusions  We demonstrate that in both mild and severe glomerular damage, lack of nidogen‐2 is associated with: (i) increased mesangioproliferation; (ii) higher mesangial matrix expansion; and (iii) reduction in glomerular capillary supply. These findings suggest a critical role for nidogen‐2 in the maintenance of glomerular structure in the diseased kidney.
Expression of beta‐defensin 4 is increased in human gastritis
Authors: Otte J.‐M. , Neumann H. M. , Brand S. , Schrader H. , Schmidt W. E. , Schmitz F.
Published: January 2009

Background  Infection with Helicobacter pylori (H. pylori) leads to the initiation of innate immune responses with increased antimicrobial peptide (AMP) expression in the gastric epithelium. This study aimed to determine the expression of the novel peptides beta‐defensin 4 (hBD‐4) and RNase 7 in infectious and non‐infectious gastritis. Furthermore, pattern recognition receptors and mechanisms of regulation were characterized.

Materials and methods  Expression of AMPs was quantified by real‐time PCR in biopsies obtained from healthy individuals and patients with infectious and non‐infectious gastritis as well as in AGS gastric epithelial cells infected with H. pylori. Distribution of hBD‐4 in the gastric mucosa was characterized by in‐situ hybridisation and immunohistochemistry. The role of Toll‐like receptors (TLRs) 2 and 4 and associated signalling pathways was addressed.

Results  hBD‐4 was expressed at low levels in gastric epithelial cells and was significantly upregulated in infectious and non‐infectious gastritis. Standard eradication but not acid suppression therapy significantly decreased hBD‐4 expression. Cytotoxin associated gene (cag)A positive H. pylori significantly increased the expression of hBD‐4 whereas cagA negative organisms, non‐viable bacteria or culture supernatants had no significant effect. Overexpression and downregulation of TLRs was not associated with an altered hBD‐4 expression. However, blocking experiments revealed an essential role for the p38 mitogen‐activated protein kinase. RNase7 was inconsistently expressed in biopsies and not significantly upregulated by H. pylori.

Conclusions  hBD‐4 may play a significant role in H. pylori associated gastritis. Inconsistent expression of RNase 7 does not support a pivotal role for this peptide in response to infection with H. pylori.
Initiator titration complex formed at datA with the aid of IHF regulates replication timing in Escherichia coli
Authors: Nozaki Shingo , Yamada Yoshitaka , Ogawa Tohru
Published: January 2009

The initiation of replication in Escherichia coli is negatively controlled by a mechanism referred to as ‘initiator titration’, a process by which the initiator protein, DnaA, is titrated to newly replicated binding sequences on the chromosome to reduce the initiation potential for replication. Initiator titration occurs predominantly at the datA locus that binds exceptionally large amounts of DnaA molecules to prevent aberrant initiations. We found that this was enabled by integration host factor (IHF). Within datA, there is a consensus IHF recognition sequence between the two DnaA recognition sequences (DnaA boxes) essential for its function. Binding of IHF to this site was demonstrated both in vitro and in vivo. Disruption of the core sequence in the consensus of the IHF‐binding resulted in increased origin concentration as observed in ΔdatA cells. Furthermore, the number of DnaA molecules bound to datA was reduced in cells carrying a disruption in the IHF‐binding core sequence. The IHF‐binding site and the essential DnaA boxes had to be located at a proper distance and orientation to maintain the accurate initiation timing. Therefore, IHF is a unique element in the control of replication initiation that acts negatively at datA, while known to act as a positive regulator at oriC.
Management of haemophilic pseudotumours with special emphasis on radiotherapy and arterial embolization
Authors: ESPANDAR R. , HEIDARI P. , RODRIGUEZ‐MERCHAN E. C.
Published: January 2009

Summary.  The haemophilic pseudotumour is an expanding destructive haematoma, which is associated with a considerable amount of morbidity in haemophilic patients. Its prevention is paramount. In fact, this goal can be achieved by primary prophylaxis to avoid muscle haematomas and by adequate and long‐term haematological treatment of muscle haematomas in case they appear. At the moment, surgical excision of pseudotumour is the preferred treatment by many authors. However, there are instances that surgical extraction of the lesion is not feasible. In such situations, radiotherapy and arterial embolization should be considered either alone or as an adjunct to surgery. Conservative management using a combination of radiotherapy and replacement therapy should be considered for treating haemophilic bone pseudotumours, which are located in the skull or in the distal parts of the limbs, especially in conditions where some impediments to surgical excision exist. In fact, the radiation should be delivered to the lesion site in small fragments of 2 Gy or less to a total dosage of 6–23.5 Gy, which is the most recommended radiation dosage, at the moment. Therapeutic arterial embolization of haemophilic pseudotumours should be considered in lesions of large size, especially in pseudotumours of pelvic region, as it may effectively reduce its size and decrease the risk of bleeding complications during surgery. Nevertheless, in view of its temporary effect, embolization may better be performed, as a preparatory procedure, at best about 2 weeks prior to surgery. This time lapse will allow for mass shrinkage but is insufficient for vessel restoration.
The plasma concentration of activated protein C appears normal in patients with haemophilia
Authors: SCHULMAN S. , EELDE A. , BLOMBÄCK M. , STENFLO J.
Published: January 2009

Summary.  Increased concentration of activated protein C (APC) has been observed in patients with thromboembolic disorders, but whether the level of APC in patients with bleeding disorders is decreased remains unknown. Seventy patients with haemophilia A or B with mild, moderate or severe form were studied. Detailed information on bleeding, arthropathy and factor consumption was collected during a 10‐year period. The clinical severity of the disease was expressed as the Hemophilia Severity Score (HSS). Plasma concentration of APC was measured as APC in complex with protein C inhibitor. The median concentration of APC‐PCI complex in patients with haemophilia was 0.14 μg L−1 and it did not differ between the types and forms. In 16 patients with severe haemophilia A and the inversion mutation in intron 22, there was no correlation between clinical severity and the concentration of APC‐PCI complex. Patients with haemophilia appear to generate normal concentrations of APC during basal conditions. APC does not seem to be an important modulator of the phenotypic expression of haemophilia.
Seedling root morphology and biomass allocation of 62 tropical tree species in relation to drought‐ and shade‐tolerance
Authors: Markesteijn Lars , Poorter Lourens
Published: January 2009

Water availability is the main determinant of species’ distribution in lowland tropical forests. Species’ occurrence along water availability gradients depends on their ability to tolerate drought.

To identify species’ traits underlying drought‐tolerance we excavated first year seedlings of 62 dry and moist forest tree species at the onset of the dry season. We evaluate how morphological seedling traits differ between forests, and whether functional groups of species can be identified based on trait relations. We also compare seedling traits along independent axes of drought and shade‐tolerance to assess a hypothesized trade‐off.

Seedlings of dry forest species improve water foraging capacity in deep soil layers by an increased below‐ground biomass allocation and by having deep roots. They minimize the risk of cavitation by making dense stems, and reduce transpiration by producing less leaf tissue. Moist forest seedlings have large leaf areas and a greater above‐ground biomass, to maximize light interception, and long, cheap, branched root systems, to increase water and nutrient capture.

Associations among seedling traits reveal three major drought strategies: (i) evergreen drought‐tolerant species have high biomass investment in enduring organs, minimize cavitation and minimize transpiration to persist under dry conditions; (ii) drought‐avoiding species maximize resource capture during a limited growing season and then avoid stress with a deciduous leaf habit in the dry season; (iii) drought‐intolerant species maximize both below‐ and above‐ground resource capture to increase competitiveness for light, but are consequently precluded from dry habitats.

We found no direct trade‐off between drought‐ and shade‐tolerance, because they depend largely on different morphological adaptations. Drought‐tolerance is supported by a high biomass investment to the root system, whereas shade‐tolerance is mainly promoted by a low growth rate and low SLA.

Synthesis. We conclude that there are three general adaptation strategies of drought‐tolerance, which seemingly hold true across biomes and for different life forms. Drought‐ and shade‐tolerance are largely independent from one another, suggesting a high potential for niche differentiation, as species’ specialization can occur at different combinations of water and light availability.
Refining the stress‐gradient hypothesis for competition and facilitation in plant communities
Authors: Maestre Fernando T. , Callaway Ragan M. , Valladares Fernando , Lortie Christopher J.
Published: January 2009

The stress‐gradient hypothesis (SGH) predicts that the frequency of facilitative and competitive interactions will vary inversely across abiotic stress gradients, with facilitation being more common in conditions of high abiotic stress relative to more benign abiotic conditions. With notable exceptions, most tests of the SGH have studied the interaction between a single pair or a few pairs of species, and thus have evaluated shifts in the magnitude and direction of pair‐wise interactions along stress gradients, rather than shifts in the general frequency of interactions.

The SGH has been supported by numerous studies in many ecosystems, has provided a crucial foundation for studying the interplay between facilitation and competition in plant communities, and has a high heuristic value. However, recent empirical research indicates that factors like the variation among species and the nature of the stress gradient studied add complexity not considered in the SGH, creating an opportunity to extend the SGH's general conceptual framework.

We suggest that one approach for extending the SGH framework is to differentiate between the original idea of how ‘common’ interactions might be along stress gradients and the ubiquitous empirical approach of studying shifts in the strength of pair‐wise interactions. Furthermore, by explicitly considering the life history of the interacting species (relative tolerance to stress vs. competitive ability) and the characteristics of the stress factor (resource vs. non‐resource) we may be able to greatly refine specific predictions relevant to the SGH.

We propose that the general pattern predicted by the SGH would hold more frequently for some combinations of life histories and stress factor, particularly when the benefactor and beneficiary species are mostly competitive and stress‐tolerant, respectively. However, we also predict that other combinations are likely to yield different results. For example, the effect of neighbours can be negative at both ends of the stress gradient when both interacting species have similar ‘competitive’ or ‘stress‐tolerant’ life histories and the abiotic stress gradient is driven by a resource (e.g. water).

Synthesis. The extension of the SGH presented here provides specific and testable hypotheses to foster research and helps to reconcile potential discrepancies among previous studies. It represents an important step in incorporating the complexity and species‐specificity of potential outcomes into models and theories addressing how plant–plant interactions change along stress gradients.
Effects of evening bright light exposure on melatonin, body temperature and sleep
Authors: BUNNELL DAVID E. , TREIBER SCOTT P. , PHILLIPS NATHAN H. , BERGER RALPH J.
Published: January 2009

SUMMARY  Five male subjects were exposed to a single 2‐h period of bright (2500 lux) or dim (<100 lux) light prior to sleep on two consecutive nights. The two conditions were repeated the following week in opposite order. Bright light significantly suppressed salivary melatonin and raised rectal temperature 0.3°C (which remained elevated during the first 1.5 h of sleep), without affecting tympanic temperature. Bright light also increased REM latency, NREM period length, EEG spectral power in low frequency, 0.75‐8 Hz and sigma, 12–14 Hz (sleep spindle) bandwidths during the first hour of sleep, and power of all frequency bands (0.5–32 Hz) within the first NREMP. Potentiation of EEG slow wave activity (0.5‐4.0 Hz) by bright light persisted through the end of the second NREMP. The enhanced low‐frequency power and delayed REM sleep after bright light exposure could represent a circadian phase‐shift and/or the effect of an elevated rectal temperature, possibly mediated by the suppression of melatonin.
Psychometric evaluation of the Stanford Sleepiness Scale
Authors: MACLEAN ALISTAIR W. , FEKKEN G. CYNTHIA , SASKIN PAUL , KNOWLES JOHN B.
Published: January 2009

SUMMARY  Two assumptions underlying the Stanford Sleepiness Scale (SSS) were evaluated: that the descriptors defining each level of the scale are equivalent ways of characterizing a particular level of sleepiness; and that sleepiness, thus measured, is an unidimensional construct. Twenty‐four True/False items were derived from the descriptors at each level of the SSS. This revised scale was administered to 340 undergraduates in a questionnaire which also included: the SSS; four visual analogue scales; items identifying the subject's age, sex, and circadian type; and the time of administration. Analyses of the responses indicated that endorsement of items on the revised scale was not consistent with the SSS level endorsed, indicating that the descriptors at each scale level are not equivalent. A principal components analysis revealed two components, tentatively identified as activation and sleepiness, accounting, respectively, for 24.2 and 20.6% of the variance. It was concluded that sleepiness is not an unidimensional construct. Further studies are necessary to elucidate the nature of its components.
Monoamine and metabolite levels in the cerebrospinal fluid of hibernating and euthermic marmots
Authors: REID MALCOLM S. , KILDUFF THOMAS S. , ROMERO L. MICHAEL , FLORANT GREGORY L. , DEMENT WILLIAM C. , HELLER H. CRAIG
Published: January 2009

SUMMARY  Cerebrospinal fluid from yellow‐bellied marmots, Marmota flaviventris, was analysed for monoamine and monoamine metabolite content during euthermia and deep hibernation. Dopamine (DA) levels were decreased, while DA metabolite levels, dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), were dramatically increased in hibernating marmots. Serotonin (5‐HT) and 5‐hydroxyindoleacetic acid (5HIAA) levels were also greatly enhanced during hibernation while norepinephrine (NE) levels were only moderately increased. These findings demonstrate that cerebrospinal monoamine levels are dynamically altered during hibernation, such that DA versus 5‐HT and NE levels undergo opposite changes. Therefore, these data indicate that DA, 5‐HT and NE neuronal systems are differentially altered during hibernation in mammals.
Gender differences in sleep architecture in sleep apnoea syndrome
Authors: VALENCIA‐FLORES MATILDE , BLIWISE DONALD L. , GUILLEMINAULT CHRISTIAN , RHOADS NANCY PATTERSON , CLERK ALEX
Published: January 2009

SUMMARY  This study compared sleep architecture in women and men with sleep apnoea syndrome. Women (n= 126) had longer sleep latencies, greater amounts of slow wave sleep, and fewer awakenings during the night than men (n= 181), despite no differences in age, RDI (Respiratory Disturbance Index) or oxygen saturation. In a subgroup of men and women treated with nasal CPAP, gender differences generally persisted. There was no difference in the complaint of daytime sleepiness between the groups, but the women reported more fatigue during the day than the men, as well as complaining about more sleep disturbance at night. We interpret these differences in terms of known gender differences in sleep architecture and sleep complaints.
Concepts and models of sleep regulation: an overview
Authors: BORBÉLY ALEXANDER A. , ACHERMANN PETER
Published: January 2009

SUMMARY  Various mathematical models have been proposed to account for circadian, ultradian and homeostatic aspects of sleep regulation. Most circadian models assume that multiple oscillators underlie the differences in period and entrainment properties of the sleep/wake cycle and other rhythms (e.g. body temperature). Interactions of the oscillators have been postulated to account for multimodal sleep/wake patterns. The ultradian models simulate the cyclic alternation of nonREM sleep and REM sleep by assuming a reciprocal interaction of two cell groups. The homeostatic models propose that a sleep/wake dependent process (Process S) underlies the rise in sleep pressure during waking and its decay during sleep. The time course of this process has been derived from EEG slow‐wave activity, an indicator of nonREM sleep intensity. The predictions of homeostatic models have been most extensively tested in experiments. The interaction of Process S with a single circadian process can account for multimodal sleep/wake patterns, internal desynchronization and the time course of daytime sleepiness. Close links have emerged between the processes postulated by the various models and specific brain mechanisms. Due to its recent quantitative elaboration and experimental validation, the modelling approach has become one of the potent research strategies in sleep science.
The relationship between circadian and hemicircadian components of human endogenous temperature rhythms
Authors: KRONAUER RICHARD E. , JEWETT MEGAN E.
Published: January 2009

SUMMARY  A review of constant routine data from normative and phase‐shifted subjects shows that the hemicircadian and circadian components of fitted temperature data are only weakly linked. In these data sets, on average, hemicircadian amplitude is one‐third of the circadian amplitude and the hemicircadian minimum occurs 1.7 h earlier than the circadian minimum. However, their variations about these means are largely independent. In addition the hemicircadian component was much less affected by bright light stimuli which strongly reduced the circadian component. The circadian and hemicircadian processes represented in these temperature data correspond to those reported in studies of human sleep/wake propensity.
Muscle nerve sympathetic activity during sleep and its change with arousal response
Authors: SHIMIZU TETSUO , TAKAHASHI YUJI , SUZUKI KAZUMASA , KOGAWA SUSUMU , TASHIRO TETSUO , TAKAHASI KENICHI , HISHIKAWA YASUO
Published: January 2009

SUMMARY Muscle nerve sympathetic activity (MSA) was recorded from the peroneal nerve during wakefulness and in different sleep states in healthy young adults. The burst rate (BR) of MSA significantly decreased in NREM, but not in REM sleep, compared with that during wakefulness. Transient increases of MSA frequently appeared in association with rapid eye movements during REM sleep. K‐complexes in Stage 2 were almost always accompanied by a burst of MSA, and were followed by a transient elevation of arterial blood pressure. Auditory stimuli applied in sleep induced a burst of MSA followed by a transient increase of arterial blood pressure, only when they elicited an arousal response in the EEG, such as a K‐complex, transient EEG desynchronization, or a short train of alpha waves. The same stimuli applied during wakefulness did not induce such changes in MSA and in arterial blood pressure.
Sleep architecture in agenesis of the corpus callosum: laboratory assessment of four cases
Authors: NIELSEN TORE , MONTPLAISIR JACQUES , LASSONDE MARYSE
Published: January 2009

SUMMARY  Whether the corpus callosum is essential for normal human sleep cannot be decided from current knowledge. We thus studied sleep architecture in four subjects with agenesis of the corpus callosum (ACC) and four control subjects matched for age, gender, and hand preference. All‐night EEG, EOG, and EMG activity were monitored in the laboratory for one adaptation night and one data acquisition night. Standard sleep variables were calculated for the second night.

Agenesis subjects were found to have a greater percentage of stage 3 + 4 sleep and a lower percentage of stage 2 sleep than control subjects. Agenesis subjects also tended to have more REM sleep periods and a shorter REM cycle length than controls.

The pattern of results is similar to that produced by partial callosotomy. It is also relevant to two hypotheses about the function of the corpus callosum in sleep. First, the corpus callosum may facilitate synchronization of activity between homologous regions in the two hemispheres but interfere with synchronization of neuronal populations within each hemisphere. Its absence may thus explain both an augmentation of slow‐wave activity (and thus more slow‐wave sleep) and a decrease in interhemispheric EEG coherence. Secondly, the corpus callosum may play a role in the regulation of the ultradian rhythm which underlies timing and duration of REM sleep.
24‐h variation of vigilance in the cockroach Blaberus giganteus
Authors: TOBLER IRENE , NEUNER‐JEHLE MARTIN
Published: January 2009

SUMMARY  Our objective was to investigate whether sleep‐like states occur in the cockroach, Blaberus giganteus by applying the methods formerly used for another cockroach species, Leucophaea maderae and the scorpions, Heterometrus and Pandinus. The behaviour of isolated animals (n= 10) kept under LD 12:12 h was recorded by time‐lapse video for three consecutive 24‐h periods. Nine behavioural states were scored for 1‐min real‐time epochs. Rest was subdivided into 4 sub‐states on the basis of body posture and the position of the antennae. The cockroaches showed a nocturnal behaviour exhibiting a bout of locomotion at dark onset which lasted several hours, and a preference for rest in the light period. Immobility with both the body and the antennae touching the substrate (state 1) was the predominating state in the light period.

In order to establish whether the sub‐states of rest represented different levels of vigilance the arousal threshold was measured by determining the latency of a behavioural response to a vibration stimulus. The levels of arousal differed significantly in four behavioural states in the light period but not in the dark period. In state 1 the animals exhibited the lowest arousal whereas in the activity states arousal was the highest. The state with the highest arousal threshold occurred in the beginning of the light period. Thereafter, arousal progressively increased and remained relatively high during the dark period.

The effect of 6‐h deprivation of rest by the gentle shaking of the cages whenever the animals were immobile, resulted in a reduced latency to state 1, a small increase of state 1 and a more prominent initial increase of activity during recovery.

In conclusion, this study provides evidence for the existence of a 24‐h variation of vigilance in the cockroach. It further indicates that a ‘rest deficit’ gives rise to a compensatory response. The data support the notion that sleep‐like states are present in these insects.
Spontaneous phasic activity in the brain: differences between waves in lateral geniculate and central lateral nuclei across sleep states
Authors: SANFORD LARRY D. , MORRISON ADRIAN R. , BALL WILLIAM A. , ROSS RICHARD J. , MANN GRAZIELLA L.
Published: January 2009

SUMMARY  Ponto‐geniculo‐occipital (PGO) waves are spontaneously‐occurring macropotential waveforms recorded in the pons, lateral geniculate body (LGB) and occipital cortex. PGO waves mark the onset and course of rapid eye movement sleep (REM). PGO‐like waves can be recorded in several brain areas including the thalamic central lateral nucleus (CL). Alerting stimuli elicit PGO waves (PGOE) from LGB and waves from CL (CLE) in all behavioural states. We compared spontaneous activity in LGB and CL across behavioral states to examine the relationship of CL waves to PGO waves. Spontaneous waves in LGB and CL may occur concurrently or separately in all states. Although REM is marked by a high level of LGB PGO activity, CL waves are rare. Frequencies of CL and LGB waves are similar in non‐REM (NREM) although the waves do not necessarily occur at the same time. These findings suggest that the widespread phasic activity recorded throughout the brain in sleep cannot be assumed to be a non‐specific unitary phenomenon propagated from a single brainstem generator.
Sleep studies for sleep‐related breathing disorders
Authors: STRADLING J.R.
Published: January 2009

SUMMARY  Our understanding of sleep‐related breathing disorders is still in a period of rapid change. Considerable uncertainty exists in several major areas of patient assessment. Although early definitions of sleep apnoea enshrined the concept of rigid guidelines, such an approach is no longer helpful, and may constrain potential advances. The recognition of the basic pathophysiological events in obstructive sleep apnoea (OSA) has evolved from purely apnoeas, to include hypopnoeas, and now to increased upper airway resistance alone. Our view as to the significant consequences of such respiratory events has also evolved from alterations to the classic sleep architecture, to hypoxic events, and now to micro‐arousals and cardio‐vascular events. The exact nature of a significant arousal is also far from clear, with the suggestion that perhaps even EEG based approaches to their measurement may not be telling us the whole story. Finally, the frequency of such respiratory events and their consequences, that lead to significant symptoms and long‐term damage, is not known either. Thus, given this situation, the best we can achieve is broad guidelines that stress the main important physiological events and their consequences that need to be assessed, and then interpreted in conjunction with the patient's symptoms. This will not necessarily be the same for all patients and this report offers some general guidance, based on the experience of several centres throughout Europe.
Mechanisms underlying oneiric behaviour released in REM sleep by pontine lesions in cats
Authors: MORRISON ADRIAN A.
Published: January 2009

SUMMARY  Bilateral thermal lesions in the feline pontine tegmentum release elaborate behaviours during rapid eye movement sleep (REM). The behaviours, which are lesion‐site specific, are consistent with the brain's paradoxical appearance of ‘alertness’ in REM and are largely isolated from environmental events, as are human dreams. This phenomenon may aid in understanding the neurophysiology underlying human dreams but offers little to the unravelling of their cognitive aspects.
A neuronal group theory of sleep function
Authors: KRUEGER JAMES M. , OBÄL FERENC
Published: January 2009

SUMMARY A new theory of sleep function is presented within the context of the neuronal group selection hypothesis, which emphasizes that neuronal groups compete for neurons via use‐dependent synaptic formation and atrophy. It is hypothesized that sleep serves to stabilize these competitive processes by providing a pattern of stimulation that serves to maintain a synaptic infrastructure upon which wakefulness‐driven synaptic changes are superimposed. Sleep is ‘quantal’ in nature in that sleep is a statistical property of a population of neuronal groups in different states. The theory unifies past theories of sleep function yet simultaneously provides a fundamental new paradigm for sleep research.
The role of slow‐wave sleep on the duration of quiet sleep in infants
Authors: PEIRANO PATRICIO , FAGIOLI IGINO , BES FREDERIK , SALZARULO PIERO
Published: January 2009

SUMMARY  The duration of quiet sleep (QS) phases has been shown to increase during the first year of life. Slow‐wave sleep (SWS) appears in about half of the QS phases beyond 20 weeks. In order to evaluate the role of SWS in the lengthening of QS phase duration during the first year of life, we looked at 48 normal full‐term infants (aged between 1 and 54 weeks), recorded for a whole‐night period. Records included electro‐encephalogram (EEG) and other polygraphic parameters. Infants were separated into two groups: (1) those who did not show SWS episodes at all, and (2) those who show both QS phases with (QS SWS+) and without (QS SWS‐) SWS episodes. In group 2 the duration of QS SWS+ was longer than that of QS SWS, as well as longer than that of QS of group 1. Group 1 had a duration of QS phases similar to that of QS SWS‐. The duration of QS SWS+ depended both on the SWS latency and SWS duration. The lengthening of QS phases with age is accounted for by those phases containing SWS episodes, reflecting a maturational restructuring of QS.
Sleep, snoring and smoking in high school students
Authors: DELASNERIE‐LAUPRETRE NICOLE , PATOIS ELISABETH , VALATX JEAN‐LOUIS , KAUFFMANN FRANCINE , ALPEROVITCH ANNICK
Published: January 2009

SUMMARY  The relationship between snoring, sleep and smoking was investigated in young students from a survey by self‐administered questionnaire on sleep habits, conducted in high schools in the educational district of Lyons (France). Our sample consisted of 11,417 boys and 13,265 girls between 15 and 20 years of age.

We found that 28.4% of girls and 38.8% of boys reported that they snored. In both sexes, snoring was associated with short (<7h) and long (>10h) sleep length, nocturnal awakenings and daytime sleepiness. Smoking was a risk factor for snoring. Multiple logistic regression showed that the odds‐ratio for habitual snoring increased when tobacco consumption increased from a 1.30 (moderate smokers) to 2.26 (heavy smokers) in girls and from 1.38 to 2.09 in boys.

This dose‐effect relationship between smoking and snoring suggests that a substantial proportion of snoring cases is attributable to tobacco consumption in young students.
Sleep in the harp seal (Pagophilus groenlandica). Peculiarities of sleep in pups during the first month of their lives
Authors: LYAMIN OLEG I. , OLEKSENKO ALEXANDER I. , POLYAKOVA IRINA G.
Published: January 2009

SUMMARY  Two white‐coated (ten day‐old) and two grey‐spotted (one month‐old) pups of the harp seal were implanted with electrodes for recording the electrocorticograms of the two hemispheres, electrocardiogram, electrooculogram and electromyogram of the neck muscles. In all individuals ECoG slow waves always developed synchronously in both hemispheres. When white and grey pups were recorded on the snow, the amount of active wakefulness was, respectively, 21.1% (s.e. 11.8%) and 29.9% (s.e. 0.2%) of total recording time, quiet wakefulness = 27.1% (s.e. 4.4%) and 38.2% (s.e. 6.6%), drowsiness = 7.7% (s.e. 0.5%) and 2.07% (s.e. 0.9%), light slow‐wave sleep (SWS) = 15.1% (s.e. 3.2%) and 13.0% (s.e. 2.4%), deep SWS = 21.2% (s.e. 2.4%) and 13.8% (s.e. 3.8%), paradoxical sleep (PS) = 8.0% (s.e. 1.4%) and 7.4% (s.e. 1.1%). PS always followed SWS and was fragmented. Respiration was very rare and irregular in PS and a considerable part of PS episodes occurred within a single respiratory pause. During SWS all pups displayed respiratory pauses of up to three minutes, alternating with hyperventilation periods. Heart rate was lowest in PS. Peculiarities of sleep and the pace of sleep pattern development during the first month in seals may be adaptive to the cold environment and ice field drifting in their habitat.