bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth of InAlAs self-assembled quantum dots on InAlGaAs∕InP for 1.55μm laser applications by metalorganic chemical vapor deposition
Authors: Zhang X. B. , Ryou J. H. , Dupuis R. D.
Published: November 2006

We report on the growth of InAlAs self-assembled quantum dots or simply (QDs) on In0.53(Al0.5Ga0.5)0.47As matrices lattice matched on InP (001) substrates using metal organic chemical vapor deposition. We found that (1) a small amount of aluminum strongly affects the morphology of the InAlAs QDs, (2) using a long growth interruption (∼140–190s) before the growth of the QDs is an important element in QD formation, and (3) the AsH3 flow rate during the growth of QDs are very important to get high-quality and high-density QDs on the InAlGaAs surface. A bimodal size distribution of InAlAs QDs is found at low growth temperatures. However, when raising the QD growth temperature, the density of “big” InAlAs QDs becomes lower while the density of “small” QDs becomes much higher. Eventually, a high-density (∼5.1×1010cm−2) unimodal size distribution of In0.92Al0.08As QDs with emission around λ∼1.55μm is realized at the optimized growth temperature condition. The QDs and the In0.53(Al0.5Ga0.5)0.47As barrier are grown at the same temperature of 650°C.
Thermoreflectance characterization of interband transitions of In0.34Al0.66As0.85Sb0.15 expitaxy on InP
Authors: Ho C. H. , Li J. H. , Lin Y. S.
Published: November 2006

Interband transitions of a lattice matched In0.34Al0.66As0.85Sb0.15 film epitaxy on InP (InAlAsSb∕InP) has been characterized using thermoreflectance (TR) measurements in the temperature range between 20 and 300K. The low-temperature TR spectrum of InAlAsSb clearly shows a lot of interband transition features present at energies ranging from 1.25to5.5eV at 20K. The observed interband transitions include one broadened feature, two excitonic peaks, and three of the other critical-point transitions consisted in the zinc-blende InAlAsSb. Transition energies for the features are analyzed and their transition origins are characterized.
A methyldiazene (HNNCH
3
)-derived species bound to the nitrogenase active-site FeMo cofactor: Implications for mechanism
Authors: Barney Brett M. , Lukoyanov Dmitriy , Yang Tran-Chin , Dean Dennis R. , Hoffman Brian M. , Seefeldt Lance C.
Published: November 2006

Methyldiazene (HN

N

CH
3
) isotopomers labeled with
15
N at the terminal or internal nitrogens or with
13
C or
2
H were used as substrates for the nitrogenase α-195
Gln
-substituted MoFe protein. Freeze quenching under turnover traps an S = ½ state that has been characterized by EPR and
1
H-,
15
N-, and
13
C-electron nuclear double resonance spectroscopies. These studies disclosed the following: (
i
) a methyldiazene-derived species is bound to the active-site FeMo cofactor; (
ii
) this species binds through an [-NH
x
] fragment whose N derives from the methyldiazene terminal N; and (
iii
) the internal N from methyldiazene probably does not bind to FeMo cofactor. These results constrain possible mechanisms for reduction of methyldiazene. In the Chatt–Schrock mechanism for N
2
reduction, H atoms sequentially add to the distal N before N-N bond cleavage (
d
-mechanism). In a
d
-mechanism for methyldiazene reduction, a bound [-NH
x
] fragment only occurs after reduction by three electrons, which leads to N-N bond cleavage and the release of the first NH
3
. Thus, the appearance of bound [-NH
x
] is compatible with the
d
-mechanism only if it represents a late stage in the reduction process. In contrast are mechanisms where H atoms add alternately to distal and proximal nitrogens before N-N cleavage (
a
-mechanism) and release of the first NH
3
after reduction by five electrons. An [-NH
x
] fragment would be bound at every stage of methyldiazene reduction in an
a
-mechanism. Although current information does not rule out the
d
-mechanism, the
a
-mechanism is more attractive because proton delivery to substrate has been specifically compromised in α-195
Gln
-substituted MoFe protein.
Structural and functional MRI reveals multiple retinal layers
Authors: Cheng Haiying , Nair Govind , Walker Tiffany A. , Kim Moon K. , Pardue Machelle T. , Thulé Peter M. , Olson Darin E. , Duong Timothy Q.
Published: November 2006

MRI is a noninvasive diagnostic modality that reveals anatomy, physiology, and function
in vivo
without depth limitation or optical interference. MRI application to the retina, however, remains challenging. We improved spatial resolution to resolve layer-specific structure and functional responses in the retina and confirmed the laminar resolution in an established animal model of retinal degeneration. Structural MRI of normal rat retinas revealed three bands corresponding histologically to (
i
) the combined ganglion cell layer/inner nuclear layer plus the embedded retinal vessels, (
ii
) the avascular outer nuclear (photoreceptor) layer and its photoreceptor segments, and (
iii
) the choroidal vascular layer. Imaging with an intravascular contrast agent (gadolinium-diethylene-tri-amine-pentaacetic acid) enhanced the retinal and choroidal vascular layers bounding the retina, but not the avascular outer nuclear layer and the vitreous. Similarly, blood-oxygen-level-dependent (BOLD) functional MRI revealed layer-specific responses to hyperoxia and hypercapnia. Importantly, layer-specific BOLD responses in the two vascular layers were divergent, suggesting the two vasculatures are differentially regulated. To corroborate sensitivity and specificity, we applied layer-specific MRI to document photoreceptor degeneration in Royal College of Surgeons rats. Consistent with histology, layer-specific MRI detected degeneration of the outer nuclear layer. Surprisingly, MRI revealed increased thickness in the choroidal vascular layer and diminished BOLD responses to hyperoxia and hypercapnia in the Royal College of Surgeons rat retinas, suggesting perturbation of vascular reactivity secondary to photoreceptor loss. We conclude that MRI is a powerful investigative tool capable of resolving lamina-specific structures and functional responses in the retina as well as probing lamina-specific changes in retinal diseases.
A single mutation in the castor Δ
9
-18:0-desaturase changes reaction partitioning from desaturation to oxidase chemistry
Authors: Guy Jodie E. , Abreu Isabel A. , Moche Martin , Lindqvist Ylva , Whittle Edward , Shanklin John
Published: November 2006

Sequence analysis of the diiron cluster-containing soluble desaturases suggests they are unrelated to other diiron enzymes; however, structural alignment of the core four-helix bundle of desaturases to other diiron enzymes reveals a conserved iron binding motif with similar spacing in all enzymes of this structural class, implying a common evolutionary ancestry. Detailed structural comparison of the castor desaturase with that of a peroxidase, rubrerythrin, shows remarkable conservation of both identity and geometry of residues surrounding the diiron center, with the exception of residue 199. Position 199 is occupied by a threonine in the castor desaturase, but the equivalent position in rubrerythrin contains a glutamic acid. We previously hypothesized that a carboxylate in this location facilitates oxidase chemistry in rubrerythrin by the close apposition of a residue capable of facilitating proton transfer to the activated oxygen (in a hydrophobic cavity adjacent to the diiron center based on the crystal structure of the oxygen-binding mimic azide). Here we report that desaturase mutant T199D binds substrate but its desaturase activity decreases by ≈2 × 10
3
-fold. However, it shows a >31-fold increase in peroxide-dependent oxidase activity with respect to WT desaturase, as monitored by single-turnover stopped-flow spectrometry. A 2.65-Å crystal structure of T199D reveals active-site geometry remarkably similar to that of rubrerythrin, consistent with its enhanced function as an oxidase enzyme. That a single amino acid substitution can switch reactivity from desaturation to oxidation provides experimental support for the hypothesis that the desaturase evolved from an ancestral oxidase enzyme.
Learning and memory associated with aggression in
Drosophila melanogaster
Authors: Yurkovic Alexandra , Wang Oulu , Basu Alo C. , Kravitz Edward A.
Published: November 2006

Male
Drosophila melanogaster
(Canton-S strain) exhibit aggression in competition for resources, to defend territory, and for access to mates. In the study reported here, we asked: (
i
) how long flies fight; (
ii
) whether flies adopt distinct winning and losing strategies as hierarchical relationships are established; (
iii
) whether flies exhibit experience-dependent changes in fighting strategies in later fights; and (
iv
) whether flies fight differently in second fights against familiar or unfamiliar opponents. The results showed that flies fought for up to 5 h. As hierarchical relationships were established, behavioral strategies changed: winners progressively lunged more and retreated less, whereas losers progressively lunged less and retreated more. Encounters between flies were frequent during the first 10 min of pairing and then dropped significantly. To ask whether flies remembered previous fights, they were re-paired with familiar or unfamiliar opponents after 30 min of separation. In familiar pairings, there were fewer encounters during the first 10 min of fighting than in unfamiliar pairings, and former losers fought differently against familiar winners than unfamiliar winners. Former losers lost or no decision was reached in all second fights in pairings with familiar or unfamiliar winners or with naive flies. Winner/winner, loser/loser, and naive/naive pairings revealed that losers used low-intensity strategies in later fights and were unlikely to form new hierarchical relationships, compared with winners or socially naive flies. These results strongly support the idea that learning and memory accompany the changes in social status that result from fruit fly fights.
Multipotent stromal cells from human marrow home to and promote repair of pancreatic islets and renal glomeruli in diabetic NOD/
scid
mice
Authors: Lee Ryang Hwa , Seo Min Jeong , Reger Roxanne L. , Spees Jeffrey L. , Pulin Andrey A. , Olson Scott D. , Prockop Darwin J.
Published: November 2006

We tested the hypothesis that multipotent stromal cells from human bone marrow (hMSCs) can provide a potential therapy for human diabetes mellitus. Severe but nonlethal hyperglycemia was produced in NOD/
scid
mice with daily low doses of streptozotocin on days 1–4, and hMSCs were delivered via intracardiac infusion on days 10 and 17. The hMSCs lowered blood glucose levels in the diabetic mice on day 32 relative to untreated controls (18.34 mM ± 1.12 SE vs. 27.78 mM ± 2.45 SE,
P
= 0.0019). ELISAs demonstrated that blood levels of mouse insulin were higher in the hMSC-treated as compared with untreated diabetic mice, but human insulin was not detected. PCR assays detected human Alu sequences in DNA in pancreas and kidney on day 17 or 32 but not in other tissues, except heart, into which the cells were infused. In the hMSC-treated diabetic mice, there was an increase in pancreatic islets and β cells producing mouse insulin. Rare islets contained human cells that colabeled for human insulin or PDX-1. Most of the β cells in the islets were mouse cells that expressed mouse insulin. In kidneys of hMSC-treated diabetic mice, human cells were found in the glomeruli. There was a decrease in mesangial thickening and a decrease in macrophage infiltration. A few of the human cells appeared to differentiate into glomerular endothelial cells. Therefore, the results raised the possibility that hMSCs may be useful in enhancing insulin secretion and perhaps improving the renal lesions that develop in patients with diabetes mellitus.
The
Drosophila radish
gene encodes a protein required for anesthesia-resistant memory
Authors: Folkers Elisabeth , Waddell Scott , Quinn William G.
Published: November 2006

Long-term memory in
Drosophila
is separable into two components: consolidated, anesthesia-resistant memory and long-lasting, protein-synthesis-dependent memory. The
Drosophila
memory mutant
radish
is specifically deficient in anesthesia-resistant memory and so represents the only molecular avenue to understanding this memory component. Here, we have identified the
radish
gene by positional cloning and comparative sequencing, finding a mutant stop codon in gene
CG15720
from the
Drosophila
Genome Project. Induction of a wild-type
CG15720
transgene in adult flies acutely rescues the mutant's memory defect. The
phospholipase A2
gene, previously identified as
radish
[Chiang
et al.
(2004)
Curr. Biol.
14:263–272], maps 95 kb outside the behaviorally determined deletion interval and is unlikely to be
radish
. The Radish protein is highly expressed in the mushroom bodies, centers of olfactory memory. It encodes a protein with 23 predicted cyclic-AMP-dependent protein kinase (PKA) phosphorylation sequences. The Radish protein has recently been reported to bind to Rac1 [Formstecher
et al.
(2005)
Genome Res.
15:376–384], a small GTPase that regulates cytoskeletal rearrangement and influences neuronal and synaptic morphology.
Unequal representation of cardinal vs. oblique orientations in the middle temporal visual area
Authors: Xu Xiangmin , Collins Christine E. , Khaytin Ilya , Kaas Jon H. , Casagrande Vivien A.
Published: November 2006

A possible neurobiological basis for the “oblique effect” is linked to the finding that more neural machinery is devoted to processing cardinal vs. oblique orientations in primary visual cortex (V1). We used optical imaging to determine whether more territory is devoted to processing horizontal and vertical orientations than oblique orientations in owl monkey middle temporal visual area (MT), a visual area highly sensitive to moving stimuli. We found that more of MT was devoted to representing cardinal than oblique orientations, and that the anisotropy was more prominent in parts of MT representing central vision (≤10°). Neural responses to orientations of 0° and 90° were also greater than those to 45° and 135°. In comparison, an overrepresentation of cardinal orientations in the representation of central vision in owl monkey V1 was relatively small and inconsistent. Our data could explain the greater sensitivity to motion discrimination when stimuli are moved along cardinal meridians and suggest that the neural machinery necessary to explain the motion oblique effect either originates in MT or is enhanced at this level.
Emergent magnetic moments produced by self-damage in plutonium
Authors: McCall S. K. , Fluss M. J. , Chung B. W. , McElfresh M. W. , Jackson D. D. , Chapline G. F.
Published: November 2006

Plutonium possesses the most complicated phase diagram in the periodic table, driven by the complexities of overlapping 5
f
electron orbitals. Despite the importance of the 5
f
electrons in defining the structure and physical properties, there is no experimental evidence that these electrons localize to form magnetic moments in pure Pu. Instead, a large temperature-independent Pauli susceptibility indicates that they form narrow conduction bands. Radiation damage from the α-particle decay of Pu creates numerous defects in the crystal structure, which produce a significant temperature-dependent magnetic susceptibility, χ(
T
), in both α-Pu and δ-Pu (stabilized by 4.3 atomic percent Ga). This effect can be removed by thermal annealing above room temperature. By contrast, below 35 K the radiation damage is frozen in place, permitting the evolution in χ(
T
) with increasing damage to be studied systematically. This result leads to a two-component model consisting of a Curie–Weiss term and a short-ranged interaction term consistent with disorder-induced local moment models. Thus, it is shown that self-damage creates localized magnetic moments in previously nonmagnetic plutonium.
Modelling the Impact of Community Engagement on Local Democracy
Authors: Andrews Rhys , Turner David
Published: November 2006

English local authorities are expected to promote ‘effective community engagement’. The ways in which they can do this are various, ranging from the provision of information to direct involvement in decision-making. This paper focuses on the impact of adopting different types of community engagement strategy on local democracy. Two principal types of community engagement strategy are identified: consumerist and participatory, and their potential for encouraging effective engagement is discussed, before their implications for local democracy are modelled. The paper argues that the relative priority accorded to different types of community engagement are likely to cause local democracy to evolve towards consumer, stakeholder, radical or citizen-centred democracy.
Regional Self-reliance and Economic Development: The Pembrokeshire Case
Authors: Midmore Peter , Thomas Dennis
Published: November 2006

This paper describes the outcome of an investigation to identify the scope for innovation and improvement of local economic interdependence in Pembrokeshire through greater self-reliance. It outlines a strategic framework identifying collaboration between various economic stakeholders supported by institutional actors, and provides an assessment of the potential impact of increased self-reliance on the growth and development of the Pembrokeshire economy. The paper concludes with more generalised observations regarding the lessons to be learned for self-reliance strategies in peripheral regions.
Cluster Dynamics: Corporate Strategy, Industry Evolution and Technology Trajectories - A Case Study of the East Midlands Aerospace Cluster
Authors: Smith David , Ibrahim Gamal
Published: November 2006

High-technology clusters have attracted the attention of researchers and policy-makers but studies have focused primarily on the computer, electronics and biotechnology industries; aerospace has attracted less attention. An example of a high-technology cluster based on aerospace is to be found in the East Midlands region of the UK. This paper analyses this cluster. The analysis focuses on the structure of the cluster and the implications of this structure for cluster dynamics. The impact of factors such as corporate strategy, industry evolution and technological trajectories on cluster development are analysed. Finally, the implications of cluster structure for economic development policy in the region are evaluated.
Social odours, sexual arousal and pairbonding in primates
Authors: Snowdon Charles T , Ziegler Toni E , Schultz-Darken Nancy J , Ferris Craig F
Published: November 2006

We describe the role of social odours in sexual arousal and maintaining pairbonds in biparental and cooperatively breeding primates. Social odours are complex chemical mixtures produced by an organism that can simultaneously provide information about species, kinship, sex, individuality and reproductive state. They are long lasting and have advantages over other modalities. Both sexes are sensitive to changes in odours over the reproductive cycle and experimental disruption of signals can lead to altered sexual behaviour within a pair. We demonstrate, using functional magnetic resonance imaging (fMRI), that social odours indicating reproductive state directly influence the brain areas responsible for sexual behaviour. Social odours also influence other brain areas typically involved in motivation, memory and decision making, suggesting that these signals have more complex functions in primates than mere sexual arousal. We demonstrate a rapid link between social odours and neuroendocrine responses that are modulated by a male's social status. Recent work on humans shows similar responses to social odours. We conclude with an integration of the importance of social odours on sexual arousal and maintaining pairbonds in socially biparental and cooperatively breeding species, suggesting new research directions to integrate social behaviour, neural activation and neuroendocrine responses.
Voice processing in human and non-human primates
Authors: Belin Pascal
Published: November 2006

Humans share with non-human primates a number of voice perception abilities of crucial importance in social interactions, such as the ability to identify a conspecific individual from its vocalizations. Speech perception is likely to have evolved in our ancestors on the basis of pre-existing neural mechanisms involved in extracting behaviourally relevant information from conspecific vocalizations (CVs). Studying the neural bases of voice perception in primates thus not only has the potential to shed light on cerebral mechanisms that may be—unlike those involved in speech perception—directly homologous between species, but also has direct implications for our understanding of how speech appeared in humans. In this comparative review, we focus on behavioural and neurobiological evidence relative to two issues central to voice perception in human and non-human primates: (i) are CVs ‘special’, i.e. are they analysed using dedicated cerebral mechanisms not used for other sound categories, and (ii) to what extent and using what neural mechanisms do primates identify conspecific individuals from their vocalizations?
Oxytocin, vasopressin and pair bonding: implications for autism
Authors: Hammock Elizabeth A.D , Young Larry J
Published: November 2006

Understanding the neurobiological substrates regulating normal social behaviours may provide valuable insights in human behaviour, including developmental disorders such as autism that are characterized by pervasive deficits in social behaviour. Here, we review the literature which suggests that the neuropeptides oxytocin and vasopressin play critical roles in modulating social behaviours, with a focus on their role in the regulation of social bonding in monogamous rodents. Oxytocin and vasopressin contribute to a wide variety of social behaviours, including social recognition, communication, parental care, territorial aggression and social bonding. The effects of these two neuropeptides are species-specific and depend on species-specific receptor distributions in the brain. Comparative studies in voles with divergent social structures have revealed some of the neural and genetic mechanisms of social-bonding behaviour. Prairie voles are socially monogamous; males and females form long-term pair bonds, establish a nest site and rear their offspring together. In contrast, montane and meadow voles do not form a bond with a mate and only the females take part in rearing the young. Species differences in the density of receptors for oxytocin and vasopressin in ventral forebrain reward circuitry differentially reinforce social-bonding behaviour in the two species. High levels of oxytocin receptor (OTR) in the nucleus accumbens and high levels of vasopressin 1a receptor (V1aR) in the ventral pallidum contribute to monogamous social structure in the prairie vole. While little is known about the genetic factors contributing to species-differences in OTR distribution, the species-specific distribution pattern of the V1aR is determined in part by a species-specific repetitive element, or ‘microsatellite’, in the 5′ regulatory region of the gene encoding V1aR (
avpr1a
). This microsatellite is highly expanded in the prairie vole (as well as the monogamous pine vole) compared to a very short version in the promiscuous montane and meadow voles. These species differences in microsatellite sequence are sufficient to change gene expression in cell culture. Within the prairie vole species, intraspecific variation in the microsatellite also modulates gene expression
in vitro
as well as receptor distribution patterns
in vivo
and influences the probability of social approach and bonding behaviour. Similar genetic variation in the human
AVPR1A
may contribute to variations in human social behaviour, including extremes outside the normal range of behaviour and those found in autism spectrum disorders. In sum, comparative studies in pair-bonding rodents have revealed neural and genetic mechanisms contributing to social-bonding behaviour. These studies have generated testable hypotheses regarding the motivational systems and underlying molecular neurobiology involved in social engagement and social bond formation that may have important implications for the core social deficits characterizing autism spectrum disorders.
Thermal unfolding of eosinophil cationic protein/ribonuclease 3: A nonreversible process
Authors: Nikolovski Zoran , Buzón Víctor , Ribó Marc , Moussaoui Mohammed , Vilanova Maria , Cuchillo Claudi M. , Cladera Josep , Nogués M. Victòria
Published: November 2006

Eosinophil cationic protein (ECP)/ribonuclease 3 is a member of the RNase A superfamily involved in inflammatory processes mediated by eosinophils. ECP is bactericidal, helminthotoxic, and cytotoxic to tracheal epithelium cells and to several mammalian cell lines although its RNase activity is low. We studied the thermal stability of ECP by fourth‐derivative UV absorbance spectra, circular dichroism, differential scanning calorimetry, and Fourier transform infrared spectroscopy. The T 1/2 values obtained with the different techniques were in very good agreement (T 1/2 ≈ 72°C), and the stability was maintained in the pH range between 5 and 7. The ECP calorimetric melting curve showed, in addition to the main transition, a pretransitional conformational change with a T 1/2 of 44°C. Both calorimetric transitions disappeared after successive re‐heatings, and the ratio ΔH versus ΔH vH of 2.2 indicated a significant deviation from the two‐state model. It was observed that the thermal unfolding was irreversible. The unfolding process gives rise to changes in the environment of aromatic amino acids that are partially maintained in the refolded protein with the loss of secondary structure and the formation of oligomers. From the thermodynamic analysis of ECP variants, the contribution of specific amino acids, such as Trp10 and the region 115–122, to thermal stability was also determined. The high thermal stability of ECP may contribute to its resistance to degradation when the protein is secreted to the extracellular medium during the immune response.
Effects of additives on surfactant phase behavior relevant to bacteriorhodopsin crystallization
Authors: Berger Bryan W. , Gendron Colleen M. , Lenhoff Abraham M. , Kaler Eric W.
Published: November 2006

The interactions leading to crystallization of the integral membrane protein bacteriorhodopsin solubilized in n‐octyl‐β‐D‐glucoside were investigated. Osmotic second virial coefficients (B22) were measured by self‐interaction chromatography using a wide range of additives and precipitants, including polyethylene glycol (PEG) and heptane‐1,2,3‐triol (HT). In all cases, attractive protein–detergent complex (PDC) interactions were observed near the surfactant cloud point temperature, and there is a correlation between the surfactant cloud point temperatures and PDC B22 values. Light scattering, isothermal titration calorimetry, and tensiometry reveal that although the underlying reasons for the patterns of interaction may be different for various combinations of precipitants and additives, surfactant phase behavior plays an important role in promoting crystallization. In most cases, solution conditions that led to crystallization fell within a similar range of slightly negative B22 values, suggesting that weakly attractive interactions are important as they are for soluble proteins. However, the sensitivity of the cloud point temperatures and resultant coexistence curves varied significantly as a function of precipitant type, which suggests that different types of forces are involved in driving phase separation depending on the precipitant used.
Sensitivity of secondary structure propensities to sequence differences between α‐ and γ‐synuclein: Implications for fibrillation
Authors: Marsh Joseph A. , Singh Vinay K. , Jia Zongchao , Forman‐Kay Julie D.
Published: November 2006

The synucleins are a family of intrinsically disordered proteins involved in various human diseases. α‐Synuclein has been extensively characterized due to its role in Parkinson's disease where it forms intracellular aggregates, while γ‐synuclein is overexpressed in a majority of late‐stage breast cancers. Despite fairly strong sequence similarity between the amyloid‐forming regions of α‐ and γ‐synuclein, γ‐synuclein has only a weak propensity to form amyloid fibrils. We hypothesize that the different fibrillation tendencies of α‐ and γ‐synuclein may be related to differences in structural propensities. Here we have measured chemical shifts for γ‐synuclein and compared them to previously published shifts for α‐synuclein. In order to facilitate direct comparison, we have implemented a simple new technique for re‐referencing chemical shifts that we have found to be highly effective for both disordered and folded proteins. In addition, we have developed a new method that combines different chemical shifts into a single residue‐specific secondary structure propensity (SSP) score. We observe significant differences between α‐ and γ‐synuclein secondary structure propensities. Most interestingly, γ‐synuclein has an increased α‐helical propensity in the amyloid‐forming region that is critical for α‐synuclein fibrillation, suggesting that increased structural stability in this region may protect against γ‐synuclein aggregation. This comparison of residue‐specific secondary structure propensities between intrinsically disordered homologs highlights the sensitivity of transient structure to sequence changes, which we suggest may have been exploited as an evolutionary mechanism for fast modulation of protein structure and, hence, function.
Accidental intracerebroventricular injection of anaesthetic drugs during induction of general anaesthesia
Authors: Tiefenthaler W. , Tschupik K. , Hohlrieder M. , Eisner W. , Benzer A.
Published: November 2006

A 51‐year‐old patient scheduled for surgery under general anaesthesia was accidentally given remifentanil 150 μg and propofol 1% 10 ml through an intracerebroventricular totally implantable access port placed in the right infraclavicular region, which was mistakenly thought to be an intravenous line. Severe pain in the head and neck caused the mistake to be discovered rapidly, and 20 ml of a mixture of cerebrospinal fluid and the anaesthetic drugs were aspirated from the implantable access port. The patient suffered no apparent adverse neurological sequelae.
Hypophosphataemia causing profound cardiac failure after cardiac surgery
Authors: Heames R. M. , Cope R. A.
Published: November 2006

We report the case of a patient who developed severe cardiac failure after cardiac surgery and required high‐dose inotrope infusion. The patient was found to have significant hypophosphataemia and high insulin requirements immediately after surgery. On giving intravenous phosphate, there was a rapid decrease in inotrope requirement and improved glycaemic control. This occurrence raises questions about the cause of hypophosphataemia after cardiac surgery, the possible need for pre‐operative plasma phosphate measurement and whether phosphate replacement should be part of the standard management of postoperative hypophosphataemia.
The efficacy of pharyngeal packing during routine nasal surgery – a prospective randomised controlled study
Authors: Basha S. I. , McCoy E. , Ullah R. , Kinsella J. B.
Published: November 2006

The efficacy of pharyngeal packing in the prevention of postoperative nausea and vomiting (PONV) in patients undergoing nasal surgery was evaluated in a prospective randomised controlled study. The effect of the presence of the pharyngeal pack on the incidence of postoperative sore throat was also assessed. One hundred patients were randomly allocated to one of two groups; the first had packing and the second received no packing. The placement of a pharyngeal pack was found to have no effect on the incidence of PONV but was associated with a significantly increased incidence of sore throat. The absence of a pharyngeal pack was not associated with an increase in postoperative aspiration or vomiting. We conclude that the routine placement of pharyngeal packs during uncomplicated nasal surgery has no effect on the incidence of PONV and will increase the incidence of postoperative sore throat.
Nicotinic acetylcholine receptors on basophils and mast cells
Authors: Sudheer P. S. , Hall J. E. , Donev R. , Read G. , Rowbottom A. , Williams P. E.
Published: November 2006

Anaphylaxis in response to drugs administered during anaesthesia is a rare but potentially catastrophic event. The anaesthetic drugs most commonly associated with anaphylaxis are neuromuscular blocking agents. As these drugs act on the nicotinic acetylcholine receptor of the neuromuscular junction, potentiation of anaphylaxis by a nicotinic receptor on basophils and mast cells is plausible. The aim of this study was to investigate whether nicotinic acetylcholine receptors are present on a human basophil and mast cell lines as their presence may suggest a mechanism of associated anaphylaxis. Nicotinic receptors were demonstrated on a basophil and a mast cell line using an α‐bungarotoxin–fluorescein conjugate by flow cytometry and by both conventional and confocal microscopic techniques. The identity of this receptor was confirmed by reverse transcriptase PCR and quantitative PCR.
Ghrelin does not regulate the GH response to insulin‐induced hypoglycaemia in children but could be involved in the regulation of cortisol secretion
Authors: Huber J. , Reiterer E. E. , Sudi K. , Gallistl S. , Friedl K. , Weinhandl G. , Aigner R. , Borkenstein M. H.
Published: November 2006

Objective  Ghrelin activates the growth hormone secretagogue receptor GHS‐R. It strongly stimulates GH secretion and has a role in energy homeostasis. The relationship between plasma ghrelin and cortisol levels during insulin‐induced hypoglycaemia in prepubertal and pubertal children has not yet been investigated. The aim of the present study was to establish whether insulin‐induced hypoglycaemia stimulates ghrelin secretion and whether changes in ghrelin concentrations are related to changes in GH and cortisol in children.

Design and patients  We studied a group of 20 children and adolescents (five girls, 15 boys, mean age 10·8 ± 3·7 years) undergoing insulin tolerance tests (ITTs) for clinical investigation of GH deficiency.

Measurements  Stimulation tests were performed to investigate the relationship between ghrelin, GH, cortisol and glucose levels according to age and pubertal stage by determining the ghrelin profiles during insulin‐induced hypoglycaemia (at 0, 60 and 120 min).

Results  Ghrelin was significantly and inversely related to body weight, height, body mass index (BMI) and age of children (P < 0·05). Significant changes in ghrelin levels (P = 0·00013) were found after the insulin bolus, with a decline at 60 min and an increase to baseline values at 120 min. Changes in cortisol levels were negatively correlated with changes in ghrelin at 60 min (r = –0·59, P = 0·004) and at 120 min (r = –0·605, P = 0·003).

Conclusions  This study shows that ghrelin might not regulate the GH response to insulin‐induced hypoglycaemia in prepubertal and pubertal children. A role for ghrelin in the regulation of cortisol secretion can be hypothesized concerning the negative correlation between changes in ghrelin and cortisol. Furthermore, the results imply that ghrelin secretion is age dependent and is a function of growth.
Clinical characteristics of poorly differentiated thyroid carcinomas compared with those of classical papillary thyroid carcinomas
Authors: Lin Jen‐Der , Chao Tzu‐Chieh , Hsueh Chuen
Published: November 2006

Objective  The aim of this study was to compare the clinical presentation and prognosis of poorly differentiated thyroid carcinoma (PDTC) with those of classical papillary thyroid carcinoma (PTC) to identify the appropriate surgical modalities for use in conjunction with radioactive iodide (131I) therapy and external radiotherapy for treating PDTC.

Design  Sixty‐seven PDTC patients (mean age 50·3 ± 18·1 years, range 14–82 years) underwent surgery at the Chang Gung Medical Centre (CGMC), Linkou. To compare clinical presentations and treatment outcomes, 134 age‐ and gender‐matched patients with classical PTC were selected randomly from the patient database at CGMC.

Results  Of the 67 PDTC patients, 53 underwent near‐total thyroidectomy. Following surgery, 45 were administered 131I for remnant ablation and treatment of distant metastatic disease. Forty‐one of the 67 (61·2%) patients with PDTC and 26/134 (19·4%) with classical PTC failed to achieve disease‐free status. Twenty‐four of the 67 (34·3%) PDTC patients eventually died of thyroid cancer after a mean follow‐up of 5·9 ± 0·6 years. Age and TNM staging at surgery were significant indicators of PDTC patient survival and mortality.

Conclusions  As the prognosis for PDTC patients is poorer than that for classical PTC patients, 131I treatment following surgery is useful. To improve the survival rate, early diagnosis is crucial for PDTC.
The α1S subunit of the L‐type calcium channel is not a predisposition gene for thyrotoxic periodic paralysis
Authors: Tang Nelson L. S. , Chow C. C. , Ko Gary T. C. , Tai Morris H. L. , Kwok Rachel , Yao X. Q. , Cockram Clive S.
Published: November 2006

Objective  Thyrotoxic periodic paralysis (TTP) has been associated with genetic variations in the gene encoding the alpha 1 subunit of the L‐type calcium channel (CACNA1S). Mutations in CACNA1S are known to account for the majority of cases of familial hypokalaemic periodic paralysis (HOKPP). In this study we have examined 48 genetic polymorphisms in the CACNA1S gene and genotyped a tagging set of representative polymorphisms to determine the role of this gene in TPP.

Design and patients  A genetic association study was carried out with 98 TPP patients and 162 male thyrotoxic controls. Among 47 polymorphisms evaluated for linkage disequilibrium (LD) and the spectrum of haplotypes in the Chinese population, 31 were selected as tagging single‐nucleotide polymorphisms (SNPs) for genotyping the whole sample. A new genotyping protocol was used to analyse an insertion/deletion (I/D) polymorphism.

Results  We studied the LD among 47 polymorphisms in the CACNA1S gene, which comprised a set of high‐density markers with an average of one SNP every 2 kb. Subsequently, 31 tagSNPs were genotyped for all the samples. The gene is composed of three LD blocks. With this block structure, we were confident that variations of the gene were comprehensively covered by the tagSNPs. No significant association was found between the polymorphisms and TPP.

Conclusion  We established the LD structure of this calcium channel subunit gene (CACNA1S) for the first time. However, its genetic variations are not associated with TPP in Chinese patients.
Diversity and distribution of aphids in the Qinghai–Tibetan Plateau–Himalayas
Authors: HUANG XIAOLEI , QIAO GEXIA , LEI FUMIN
Published: November 2006

Abstract1. Based on the geographic distribution database of museum specimens and published literature, the diversity and distribution of aphids in the Qinghai–Tibetan Plateau–Himalayas was studied using the GIS method.

2. A total of 646 aphid species/subspecies belonging to 195 genera in Adelgidae, Phylloxeridae, and 16 subfamilies of Aphididae were recorded from this region; among which Aphidinae shared the highest species proportion (343 species, 53.1%), followed by Greenidinae (63, 9.7%), Eriosomatinae (54, 8.3%), and Lachninae (48, 7.4%). A total of 326 species and 20 genera are endemic to this region.

3. The aphid fauna has diverse faunal components and shows affinity with other zoogeographic realms. It is also rich in alpine species.

4. The aphid fauna exhibits an asymmetric distribution pattern with few species found on the high surface of the plateau. Four distribution centres were mapped. These were (i) the associated mountainous areas of the Qinghai–Tibetan Plateau and the western Qinling Mountains and southern Gansu Province, (ii) the Hengduan Mountains Region, (iii) the eastern Himalayas, and (iv) the western Himalayas.

5. The aphid fauna of the region may have multiple origins, and has been influenced by geological and ecological factors, such as glaciers and diversified vegetation. Possible reasons for the species diversity and distribution patterns are discussed. The implications and priorities for conservation based, on these distribution patterns, are also discussed.
Inflammation affects lipid metabolism during recovery from hyperinsulinaemia
Authors: Heliövaara M. K. , Teppo A. M. , Karonen S. L. , Ebeling P.
Published: November 2006

Background  Inflammation is an established contributor in atherosclerosis and several other common diseases including diabetes. Therefore the study was to investigate how inflammatory factors affect lipid metabolism during recovery from hyperinsulinaemia in healthy individuals.

Materials and methods  A total of 22 healthy subjects [aged 27·7 ± 1·8 years; body mass index (BMI) 24·1 ± 0·8 kg m−2] participated in the study. After a 4‐h euglycaemic hyperinsulinaemia (55·9 ± 2·2 mU L−1) insulin infusion was stopped and baseline blood samples were taken. Glucose infusion at a decreasing rate continued for 120 min to maintain euglycaemia throughout the study.

Results  The free fatty acid (FFA) concentration at the 120‐min time‐point was associated with baseline alpha‐1‐acid glycoprotein (A1GP) (r = 0·57, P < 0·01), C‐reactive protein (CRP) (r = 0·54, P < 0·02) and serum amyloid A (r = 0·53, P < 0·02); in total they accounted for 54% of the variation in FFA concentration at the 120‐min time‐point. Baseline A1GP was also associated with the triglyceride concentration at the 120‐min time‐point (r = 0·66, P < 0·001). Insulin sensitivity was the most important factor associated with glucose disposal at the 120‐min time‐point, thus explaining 30% of the variation (P < 0·01). Interleukin‐6 (positive correlation) and fibrinogen (negative correlation) increased the proportion to 48% (P < 0·01). There was no significant change in the most acute‐phase proteins between baseline and the 120‐min time‐point.

Conclusion  Inflammation is an important contributor to lipid and glucose metabolism during recovery from hyperinsulinaemia.
Women with polycystic ovary syndrome are sensitive to the TNF‐α‐lowering effect of glucose‐induced hyperinsulinaemia
Authors: Puder J. J. , Varga S. , Nusbaumer C. P. G. , Zulewski H. , Bilz S. , Müller B. , Keller U.
Published: November 2006

Background  Restoration of near‐euglycaemia by intensive insulin therapy results in decreased serum levels of inflammatory mediators. The authors investigated whether the anti‐inflammatory effect of insulin was independent of its glucose‐lowering action and if this effect was intact in insulin‐resistant women with the polycystic ovary syndrome (PCOS) characterized by low‐grade chronic inflammation.

Materials and methods  Blood was drawn on the third and sixth days after progestin‐induced withdrawal bleeding in 20 young non‐diabetic women with PCOS and once between the third and sixth days of the menstrual cycle in 21 age‐matched lean healthy control women during a 75‐g oral glucose tolerance test (oGTT). Serum insulin, glucose and tumour necrosis factor alpha (TNF‐α) concentrations were measured after 0, 30, 60, 90 and 120 min.

Results  The increase in insulin and glucose concentrations during the oGTT was significantly more pronounced in patients with PCOS (one patient with impaired fasting glucose, one patient with impaired glucose tolerance, three patients with both) compared with healthy controls. The TNF‐α serum concentrations decreased in patients with PCOS (mean of both days, P = 0·004). In patients and in controls, there was an inverse correlation between the serum concentrations of insulin and of TNF‐α during oGTT (for patients, a mean of both days, P = 0·009; for controls, P = 0·047), but not between the serum concentrations of glucose and TNF‐α.

Conclusions  The decrease in TNF‐α concentrations during oGTT and the inverse correlation between endogenous hyperinsulinaemia and serum TNF‐α concentrations suggested an anti‐inflammatory effect of moderately‐high insulin concentrations. This occurred despite the presence of moderate hyperglycaemia. These findings also demonstrated a preserved responsiveness of inflammatory mediators to insulin in PCOS.
Tacrolimus treatment of plasmacytoid dendritic cells inhibits dinucleotide (CpG‐)‐induced tumour necrosis factor‐alpha secretion
Authors: Naranjo‐Gómez Mar , Climent Nuria , Cos Joan , Oliva Harold , Bofill Margarita , Gatell José M. , Gallart Teresa , Pujol‐Borrell Ricardo , Borràs Francesc E.
Published: November 2006

Tacrolimus is a widely used immunosuppressive agent. Although T cells are the main targets of these pharmacological drugs, antigen presentation may also be affected. Among antigen‐presenting cells, plasmacytoid dendritic cells (PDCs) are the main source of type I interferons upon microbial challenge, and are involved in several diseases and autoimmune disorders. The aim of this study was to evaluate whether tacrolimus can modulate the function of PDCs in vitro. Maturation and function of PDCs was determined using flow cytometry, enzyme‐linked immunosorbent assay and cytometry bead arrays. The effect of tacrolimus on PDCs was observed mainly when the cells were pretreated with the immunosuppressive agent before activation. Upon dinucleotide–oligodeoxynucleotide (CpG–ODN) activation, tacrolimus pretreated PDCs showed a significant reduction in the surface expression of co‐stimulatory molecules and human leucocyte antigen D‐related (HLA‐DR) and secreted reduced levels of tumour necrosis factor (TNF)‐α. These results show that tacrolimus treatment of PDCs impairs CpG‐induced activation, which could affect the outcome of the immune response.
Carbon addition alters vegetation composition on ex‐arable fields
Authors: ESCHEN RENÉ , MORTIMER SIMON R. , LAWSON CLARE S. , EDWARDS ANDREW R. , BROOK ALEX J. , IGUAL JOSÉ M. , HEDLUND KATARINA , SCHAFFNER URS
Published: November 2006

Recent changes in European agricultural policy have led to measures to reverse the loss of species‐rich grasslands through the creation of new areas on ex‐arable land. Ex‐arable soils are often characterized by high inorganic nitrogen (N) levels, which lead to the rapid establishment of annual and fast‐growing perennial species during the initial phase of habitat creation. The addition of carbon (C) to the soil has been suggested as a countermeasure to reduce plant‐available N and alter competitive interactions among plant species.

To test the effect of C addition on habitat creation on ex‐arable land, an experiment was set up on two recently abandoned fields in Switzerland and on two 6‐year‐old restoration sites in the UK. Carbon was added as a mixture of either sugar and sawdust or wood chips and sawdust during a period of 2 years. The effects of C addition on soil parameters and vegetation composition were assessed during the period of C additions and 1 year thereafter.

Soil nitrate concentrations were reduced at all sites within weeks of the first C addition, and remained low until cessation of the C additions. The overall effect of C addition on vegetation was a reduction in above‐ground biomass and cover. At the Swiss sites, the addition of sugar and sawdust led to a relative increase in legume and forb cover and to a decrease in grass cover. The soil N availability, composition of soil micro‐organisms and vegetation characteristics continued to be affected after cessation of C additions.

Synthesis and applications. The results suggest that C addition in grassland restoration is a useful management method to reduce N availability on ex‐arable land. Carbon addition alters the vegetation composition by creating gaps in the vegetation that facilitates the establishment of late‐seral plant species, and is most effective when started immediately after the abandonment of arable fields and applied over several years.