bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of the sex pheromone extract of individual male Lutzomyia longipalpis sandflies from six regions in Brazil
Authors: Hamilton J.G.C. , Maingon R.D.C. , Alexander B. , Ward R.D. , Brazil R.P.
Published: December 2005

Abstract.  Although the phlebotomine sandfly Lutzomyia longipalpis (Lutz & Neiva, 1912) (Diptera: Psychodidae) is generally accepted to be a species complex, it is unclear how many members there are, how they are related and which are the main vectors of leishmaniasis. The vectorial capacity of each sibling species is likely to differ, thus a means of identifying the most important vector species is of critical importance to the epidemiology and control of this debilitating disease in South and Central America. In Brazil four chemotypes have been distinguished by sex pheromone analysis. In this study the sex pheromone extracts of L. longipalpis from six regions of Brazil were analysed in detail. Samples included the sympatric 1‐spot, 2‐spot and intermediate spot morphotypes from Sobral, Ceará State. The results strongly suggest that members of the complex that produce different sex pheromones are reproductively isolated, thus strengthening the argument that the different chemotypes represent true sibling species. The study also found significant differences in morphology and the amounts of sex pheromone produced by members of each chemotype from different parts of Brazil, which suggests population substructuring that has not previously been recognized. Evidence of a fifth chemotype in Brazil is also presented.
Effects of growth light and nitrogen nutrition on the organization of the photosynthetic apparatus in leaves of a C4 plant, Amaranthus cruentus
Authors: TAZOE YOUSHI , NOGUCHI KO , TERASHIMA ICHIRO
Published: December 2005

Properties of C4 photosynthesis were examined in Amaranthus cruentus L. (NAD‐malic enzyme (ME) subtype, dicot) grown under different light and nitrogen (N) conditions, from the viewpoint of N investment into their photosynthetic components. In low‐light (LL) leaves, chlorophyll content per leaf area was greater and chlorophyll a/b ratio was lower than in high‐light (HL) leaves. These indicate that LL leaves invest more N into their light‐harvesting systems. However, this N investment did not contribute to the increase in the quantum yield of photosynthesis on the incident photon flux density (PFD) basis (Qi) in LL leaves. N allocation to ribulose 1,5‐bisphosphate carboxylase/oxygenase (Rubisco) was significantly higher in HL‐high N (HN) leaves than in other leaves. On the other hand, N allocation to C4 enzymes [phosphoenolpyruvate carboxylase (PEPC) and pyruvate Pi dikinase (PPDK)] was unaffected by the growth conditions. Maximum photosynthetic rates (Pmax) per Rubisco content were similar irrespective of the growth light treatments. Carbon isotope ratios (δ13C) in the leaf dry matter were more negative in LL leaves than in HL leaves (LL = −19.3‰, HL = −16.0‰) and independent of leaf N. Vein density was highest in HL‐HN leaves, and leaf thickness was unaffected by the growth light treatments. From these results, we conclude that A. cruentus leaves would not acclimate efficiently to low growth light.
The CLAVATA1‐related BAM1, BAM2 and BAM3 receptor kinase‐like proteins are required for meristem function in Arabidopsis
Authors: DeYoung Brody J. , Bickle Kristen L. , Schrage Katherine J. , Muskett Paul , Patel Kanu , Clark Steven E.
Published: December 2005

Organ formation at shoot and flower meristems in plants requires the maintenance of a population of centrally located stem cells and the differentiation of peripherally located daughter cells. The CLAVATA (CLV) gene products in Arabidopsis, including the CLV1 receptor‐kinase, regulate this process by promoting the differentiation of stem cells on the meristem flanks. Here, we have analyzed the developmental roles of the CLV1‐related BAM1 (derived from barely any meristem 1), BAM2 and BAM3 receptor‐like kinases. Loss‐of‐function alleles of these receptors lead to phenotypes consistent with the loss of stem cells at the shoot and flower meristem, suggesting that their developmental role is opposite to that of CLV1. These closely related receptors are further distinguished from CLV1, whose expression and function is highly specific, by having broad expression patterns and multiple developmental roles. These include a requirement for BAM1, BAM2 and BAM3 in the development of high‐ordered vascular strands within the leaf and a correlated control of leaf shape, size and symmetry. In addition, BAM1, BAM2 and BAM3 are required for male gametophyte development, as well as ovule specification and function. Significantly, the differing roles of CLV1 and BAM receptors in meristem and organ development are largely driven by differences in expression patterns.
HCF153, a novel nuclear‐encoded factor necessary during a post‐translational step in biogenesis of the cytochrome b6f complex
Authors: Lennartz Katja , Bossmann Sabine , Westhoff Peter , Bechtold Nicole , Meierhoff Karin
Published: December 2005

We have isolated the nuclear photosynthetic mutant hcf153 which shows reduced accumulation of the cytochrome b6f complex. The levels and processing patterns of the RNAs encoding the cytochrome b6f subunits are unaltered in the mutant. In vivo protein labeling experiments and analysis of polysome association revealed normal synthesis of the large chloroplast‐encoded cytochrome b6f subunits. The mutation resulted from a T‐DNA insertion and the affected nuclear gene was cloned. HCF153 encodes a 15 kDa protein containing a chloroplast transit peptide. Sequence similarity searches revealed that the protein is restricted to higher plants. A HCF153–Protein A fusion construct introduced into hcf153 mutant plants was able to substitute the function of the wild‐type protein. Fractionation of intact chloroplasts from these transgenic plants suggests that most or all of the fusion protein is tightly associated with the thylakoid membrane. Our data show that the identified factor is a novel protein that could be involved in a post‐translational step during biogenesis of the cytochrome b6f complex. It is also possible that HCF153 is necessary for translation of one of the very small subunits of the cytochrome b6f complex.
De l’alliance à la gouvernance: logiques d’action et logiques d’acteurs dans un centre financier aux entreprises desjardins
Authors: St‐pierre Julie , Bouchard Marie J.
Published: December 2005

Résumé**:  Cet article présente une étude de cas d’un Centre financier aux entreprises, une forme d’alliance stratégique entre des caisses Desjardins d’épargne et de crédit. Nous recourons à un cadre d’analyse qui permet d’expliquer à la fois ce qui préside aux accords et aux conflits qui marquent ce nouvel arrangement organisationnel. Nous appréhendons ainsi l’organisation dans sa réalité complexe, notamment les tensions que vit la coopérative qui a des activités dans un domaine hautement compétitif et marchand tel que celui du financement aux entreprises. Ceci permettra de voir qu’outre les modes de gouvernance qui existent au sein des caisses Desjardins – hiérarchique, marchand et démocratique – la nouvelle logique connexionniste est porteuse d’un modèle d’entreprise en réseau (Boltanski et Chiapello, 1999) ainsi que de nouvelles logiques d’acteurs (émergent, de l’interface et occasionnel) caractérisant l’entreprise incertaine (Francfort et al. 1995). Un nouveau mode de gouvernance en réseau vient s’articuler aux autres modes de gouvernance existants, ce qui induit des ruptures avec le cadre coopératif traditionnel tout en assurant une certaine continuité avec les valeurs coopératives.
Paediatric transfusion
Authors: New H. V.
Published: December 2005

The requirements of children undergoing transfusion should be considered as a distinct entity from those of adults. Neonates are particularly vulnerable and there have been concerns over infective or toxic risks to this group. Neonates may also have more acute side‐effects as a result of their small blood volume. Most children who are transfused will have a good life expectancy, so long‐term side‐effects will be more significant than for adults. In Britain, there are a number of transfusion components with neonatal specifications, but there appears to be some confusion, among both medical and laboratory staff, as to the appropriate use of these. Although there are many paediatric guidelines on the use of blood, there is a lack of evidence underlying these. However, there are trends to decreased blood usage in neonates and ongoing studies to investigate the appropriate use of blood for children.
HEMODYNAMIC MECHANISM OF ESOPHAGEAL VARICES
Authors: Obara Katsutoshi
Published: December 2005

We investigated the correlation between the collaterals around the esophagus and recurrence of esophageal varices in patients with portal hypertension who had undergone endoscopic injection sclerotherapy (EIS). In patients with portal hypertension, many types of collaterals around the esophagus were visualized by endoscopic ultrasonography (EUS). The collaterals outside the esophageal wall detected by EUS were divided into two groups according to the location of the veins: peri‐esophageal collateral veins (peri‐ECV) and para‐esophageal collateral veins (para‐ECV) Perforating veins are those that have penetrated the esophageal wall and have connected with either peri‐ECV or para‐ECV. We demonstrated that severe peri‐ECV and large perforating veins play an important role in the development of esophageal varices in untreated patients with portal hypertension. The results of our investigation have shown that detection of peri‐ECV and perforating veins by EUS and treatment of them by EIS appears to be important for the treatment of esophageal varices. The disappearance of peri‐ECV by EIS is essential for reducing the recurrence rate of esophageal varices. To prevent variceal recurrence, a mucosal fibrosing method using argon plasma coagulation has been widely performed in Japan. If EUS abnormalities are associated with variceal recurrence, we recommend the use of the mucosal fibrosing method. In conclusion, the presence of severe peri‐ECV and large perforating veins in the esophageal wall strongly correlate with the recurrence of esophageal varices in patients with portal hypertension. An understanding of these EUS abnormalities on the basis of hemodynamics around the esophagus is important for the management of esophageal varices in patients with portal hypertension.
Trophic regulation of Vibrio cholerae in coastal marine waters
Authors: Worden Alexandra Z. , Seidel Michael , Smriga Steven , Wick Arne , Malfatti Francesca , Bartlett Douglas , Azam Farooq
Published: December 2005

Cholera disease, caused by the bacterium Vibrio cholerae, afflicts hundreds of thousands worldwide each year. Endemic to aquatic environments, V. cholerae's proliferation and dynamics in marine systems are not well understood. Here, we show that under a variety of coastal seawater conditions V. cholerae remained primarily in a free‐living state as opposed to attaching to particles. Growth rates of free‐living V. cholerae (µ: 0.6–2.9 day−1) were high (similar to reported values for the bacterial assemblages; 0.3–2.5 day−1) particularly in phytoplankton bloom waters. However, these populations were subject to heavy grazing‐mortality by protozoan predators. Thus, grazing‐mortality counterbalanced growth, keeping V. cholerae populations in check. Net population gains were observed under particularly intense bloom conditions when V. cholerae proliferated, overcoming grazing pressure terms in part via rapid growth (> 4 doublings day−1). Our results show V. cholerae is subject to protozoan control and capable of utilizing multiple proliferation pathways in the marine environment. These findings suggest food web effects play a significant role controlling this pathogen's proliferation in coastal waters and should be considered in predictive models of disease risk.
Distribution and phylogeny of hexachlorocyclohexane‐degrading bacteria in soils from Spain
Authors: Mohn William W. , Mertens Birgit , Neufeld Josh D. , Verstraete Willy , De Lorenzo Victor
Published: December 2005

Hexachlorocyclohexane (HCH)‐degrading bacteria are believed to mediate natural attenuation of HCH contamination and have potential for active bioremediation processes. This study addressed the very limited understanding of the distribution, diversity and substrate specificity of such bacteria from 13 soil samples, varying in levels of HCH contamination, from four sites in Spain. Hexachlorocyclohexane removal occurred in 16 of 36 enrichment cultures. Hexachlorocyclohexane‐degrading populations were clearly associated with HCH‐contaminated soils, and populations growing on the δ‐HCH isomer were only found in soil contaminated with δ‐HCH. β‐Hexachlorocyclohexane was persistent in enrichment cultures, and there was no evidence for populations growing on β‐HCH. From α‐ and γ‐HCH enrichment cultures, nine HCH‐degrading isolates were obtained, which were all Sphingomonas spp. Attempts to isolate organisms from δ‐HCH enrichment cultures failed. None of the isolates grew on HCH as a sole organic substrate in pure culture. All isolates degraded α‐ and γ‐HCH, and most degraded β‐HCH. δ‐Hexachlorocyclohexane inhibited growth of most isolates, but could be degraded by cell suspensions of at least four strains. Denaturing gradient gel electrophoresis indicated that the isolates represented predominant populations in the enrichment cultures, but additional predominant populations, including some Pseudomonas spp., could not be isolated.
Isolation and characterization of Pseudoalteromonas strains with divergent polycyclic aromatic hydrocarbon catabolic properties
Authors: Hedlund Brian P. , Staley James T.
Published: December 2005

Fifteen strains of polycyclic aromatic hydrocarbon (PAH)‐catabolizing bacteria, identified as Pseudoalteromonas spp. were isolated from Eagle Harbor, Puget Sound, USA, using a most probable number procedure in which naphthalene or phenanthrene was the sole carbon and energy source. Despite having identical 16S rDNA sequences, some catabolized many PAHs, whereas others oxidized only naphthalenes. A putative naphthalene 1,2‐dioxygenase gene fragment was polymerase chain reaction‐amplified from the naphthalene‐degrading strains and shown to be almost identical to a gene present in Neptunomonas naphthovorans, suggesting horizontal transfer.
Colonization of nascent, deep‐sea hydrothermal vents by a novel Archaeal and Nanoarchaeal assemblage
Authors: McCliment Elizabeth A. , Voglesonger Kenneth M. , O'Day Peggy A. , Dunn Eileen E. , Holloway John R. , Cary S. Craig
Published: December 2005

Active deep‐sea hydrothermal vents are areas of intense mixing and severe thermal and chemical gradients, fostering a biotope rich in novel hyperthermophilic microorganisms and metabolic pathways. The goal of this study was to identify the earliest archaeal colonizers of nascent hydrothermal chimneys, organisms that may be previously uncharacterized as they are quickly replaced by a more stable climax community. During expeditions in 2001 and 2002 to the hydrothermal vents of the East Pacific Rise (EPR) (9°50′N, 104°17′W), we removed actively venting chimneys and in their place deployed mineral chambers and sampling units that promoted the growth of new, natural hydrothermal chimneys and allowed their collection within hours of formation. These samples were compared with those collected from established hydrothermal chimneys from EPR and Guaymas Basin vent sites. Using molecular and phylogenetic analysis of the 16S rDNA, we show here that at high temperatures, early colonization of a natural chimney is dominated by members of the archaeal genus Ignicoccus and its symbiont, Nanoarchaeum. We have identified 19 unique sequences closely related to the nanoarchaeal group, and five archaeal sequences that group closely with Ignicoccus. These organisms were found to colonize a natural, high temperature protochimney and vent‐like mineral assemblages deployed over high temperature outflows within 92 h. When compared phylogenetically, several of these colonizing organisms form a unique clade independent of those found in mature chimneys and low‐temperature mineral chamber samples. As a model ecosystem, the identification of pioneering consortia in deep‐sea hydrothermal vents may help advance the understanding of how early microbial life forms gained a foothold in hydrothermal systems on early Earth and potentially on other planetary bodies.
Correlation between quality of life and voiding variables in patients treated with percutaneous tibial nerve stimulation
Authors: VAN DER PAL FLOOR , VAN BALKEN MICHAEL R. , HEESAKKERS JOHN P.F.A. , DEBRUYNE FRANS M.J. , KIEMENEY LAMBERTUS A.L.M. , BEMELMANS BART L.H.
Published: December 2005

OBJECTIVE

To investigate the relationship between quality of life (QoL) and voiding variables in patients with lower urinary tract dysfunction treated with percutaneous tibial nerve stimulation (PTNS), as it is assumed that improvements in voiding will lead to a better QoL in such patients.

PATIENTS AND METHODS

The study included 30 patients with urge urinary incontinence who were treated with PTNS; 24‐h bladder diaries and QoL questionnaires (Short Form, SF‐36, and incontinence‐specific QoL) were completed at baseline and after PTNS.

RESULTS

There was a significant correlation (P < 0.05) between the number of pads used and the SF‐36 domains of physical and vitality, between the number of incontinence episodes and the SF‐36 domains of physical and role physical, between nocturia and the SF‐36 domains of general and mental health, between the mean voided volume and the SF‐36 domains of role physical and final, and between the mean voided volume and the incontinence‐specific QoL score.

CONCLUSIONS

PTNS is useful for treating refractory urge incontinence and should at least be considered as a therapeutic alternative before resorting to aggressive surgery, as voiding and QoL variables significantly and quantifiably correlate in patients with refractory urge urinary incontinence who are treated with PTNS. Patients must have a reduction of ≥ two pads/day before their QoL improves, and this might be the best definition of successful therapy for patients with urge urinary incontinence.
A population study of nocturia in Singapore
Authors: LIEW LEWIS C.H. , TIONG HO YEE , WONG MEE LIAN , PNG DAMIEN C.J. , TAN JAMES K.N.
Published: December 2005

OBJECTIVE

To estimate the prevalence of nocturia in the multiracial Asian population of Singapore, using the new International Continence Society standardized definition of one or more voids per night, and to assess its associations, bothersomeness and impact on sleep.

SUBJECTS AND METHODS

A door‐to‐door interview questionnaire survey was conducted amongst a randomly selected sample of 3000 individuals (response rate 78.2%). Nocturia and its associated problems were evaluated using questions from the International Prostate Symptom Score (IPSS), and concurrently, sociodemographic and health variables were recorded.

RESULTS

Data from 1134 women (aged 20–95 years) and 1139 men (aged 20–92 years) were analysed; the overall prevalence of nocturia (one or more voids/night) was 55.5%, with an increasing proportion in older groups (P < 0.01). Women had nocturia significantly (P = 0.015) more often than men (58% vs 53%), and it was positively associated with poor health, with the highest odds ratios (95% confidence interval) for diabetes mellitus of 2.0 (1.3–3.1), for renal disease of 6.4 (2.3–18.2), and for strokes of 3.1 (1.1–9.2). In both men and women, the median IPSS in patients with nocturia was significantly higher than that in patients without nocturia (P < 0.001). For individuals waking once a night, only 9.5% considered nocturia a problem and 13.5% complained of sleep disturbances; these values increased to 36% and 40% for individuals waking up twice or more /night.

CONCLUSION

Nocturia is a common condition amongst Singaporean adults, especially in the elderly; it has strong associations with poor health and other lower urinary tract symptoms. The degree of nocturia determines whether patients are likely to be bothered by it or have sleep disturbance, which will influence their help‐seeking behaviour.
Prospective study of individuals with long‐term urinary catheters colonized with Proteus species
Authors: MATHUR SUNIL , SULLER MARC T.E. , STICKLER DAVID J. , FENELEY ROGER C.L.
Published: December 2005

OBJECTIVES

To characterize the variability in the times catheters take to block with encrustation in patients who have Proteus in their urinary flora, and to identify factors responsible for modulating the rate of catheter encrustation and blockage.

PATIENTS AND METHODS

Twenty patients were followed prospectively for ≥ 12 weeks, with a bacteriological analysis on weekly urine samples. The pH of the voided urine samples and the pH at which crystals formed in them (the nucleation pH) were determined. Catheters were collected and examined for bacterial biofilm and crystal deposition.

RESULTS

The time that catheters took to block was 2–98 days. The mean pH of the urine voided by patients designated as slow encrusters (6.9) was not significantly different (P = 0.237) from that of rapid encrusters (7.2). However, patients whose catheters took longer to block had a significantly higher mean nucleation pH (8.1 vs 7.3, P = 0.002) and significantly higher mean safety margin between their nucleation pH and voided pH (1.17 pH units vs 0.13, P = 0.003).

CONCLUSION

The variation in the rate of catheter encrustation between individuals infected with Proteus is a function of the difference between the voided pH and the nucleation pH of their urine. The value of nucleation pH of an individual's urine varies widely, suggesting it should be possible to devise strategies to increase this value and thus reduce the rate of encrustation in those with urinary tract colonization by urease‐positive bacteria.
Calibration and dilatation with topical corticosteroid in the treatment of stenosis of neourethral meatus after hypospadias repair
Authors: RADOJICIC ZOAN I. , PEROVIC SAVA V. , STOJANOSKI KRSTE D.J.
Published: December 2005

OBJECTIVE

To assess the early disclosure and treatment of meatal stenosis after hypospadias repair, using calibration of the neourethral meatus at regular intervals to detect stenosis, and to assess the curative effects of dilatation with topical corticosteroids.

PATIENTS AND METHODS

Between 2001 and 2003, 83 boys (median age 19 months, range 12–28) had a proximal hypospadias repair using a tubularized skin island‐flap urethroplasty. The neourethra was calibrated every 7–15 days with newly designed small and fine metal sounds (5–12 F) for 3 months starting 7–10 days after surgery. The patients with meatal stenosis were treated by dilatation using topical 0.05% betamethasone cream daily (twice per day) for 3 months.

RESULTS

The mean (range) follow‐up was 29 (12–37)  months; 19 patients who developed early stenosis were treated by dilatation with topical steroids. After treatment, 14 neourethras were passable with a minimum sound of 10 F at regular 6–12 months assessments. Stenosis persisted in five patients who did not respond to the treatment; of these, a diverticulum developed in one and a fistula in two. All patients with permanent complications were re‐operated. There were no adverse effects in any of the patients treated with topical 0.05% betamethasone cream.

CONCLUSION

Early calibration and dilatation of the neourethra after hypospadias repair is a useful method for the early disclosure and treatment of meatal stenosis. The newly designed sounds made calibration/dilatation less unpleasant and more acceptable for the patient. Topical corticosteroids improved scar elasticity, which facilitated dilatation and prevented the formation of meatal stenosis.
The dorsal lamina of the rectus sheath: a suitable grafting material for the penile tunica albuginea in Peyronie's disease?
Authors: CRAATZ STEFFEN , SPANEL‐BOROWSKI KATHARINA , BEGEMANN JAN‐FRIEDRICH , OLIANAS ROBERTO , FISCH MARGIT , HOHENFELLNER RUDOLF
Published: December 2005

OBJECTIVE

To estimate the morphological suitability of human connective tissue structures from different regions as graft material in Peyronie's disease, and to present preliminary results from 12 patients with grafting of corporal bodies using autologous rectus sheath.

PATIENTS AND METHODS

In five male cadavers the penile tunica albuginea was compared with the dorsal lamina of the rectus sheath, the palmar aponeurosis, the iliotibial tract and the Achilles tendon by using histological sections stained with haematoxylin and eosin, Crossmon's trichrome stain and resorcin‐fuchsin. Surgical results and complication rates were investigated in 12 patients with Peyronie's disease after grafting the corporal bodies with autologous rectus sheath to correct their penile curvature.

RESULTS

On histology, the penile tunica albuginea showed a three‐dimensional meshwork of collagenous and elastic fibres. The dorsal lamina of the rectus sheath had a remarkably similar fibre structure. The other tissues had a different histology, with long collagenous fibres in parallel orientation and elastic fibres restricted to the loose connective tissue around blood vessels and nerves. Clinically, the penile deviation was successfully corrected in 10 patients; there were two residual deviations (15° and 35°). There were minor complications after surgery in six patients, not requiring surgery.

CONCLUSIONS

The dorsal lamina of the rectus sheath has similar morphological characteristics to the tunica albuginea, and therefore represents an ideal autologous graft; the first clinical results are promising.
Evaluating a Model by Forecast Performance*
Authors: Clements Michael P. , Hendry David F.
Published: December 2005

Although out‐of‐sample forecast performance is often deemed to be the ‘gold standard’ of evaluation, it is not in fact a good yardstick for evaluating models in general. The arguments are illustrated with reference to a recent paper byCarruth, Hooker and Oswald [Review of Economics and Statistics(1998), Vol. 80, pp. 621–628], who suggest that the good dynamic forecasts of their model support the efficiency‐wage theory on which it is based.
Nonlinear Correlograms and Partial Autocorrelograms*
Authors: Anderson Heather M. , Vahid Farshid
Published: December 2005

This paper proposes neural network‐based measures of predictability in conditional mean, and then uses them to construct nonlinear analogues to autocorrelograms and partial autocorrelograms. In contrast to other measures of nonlinear dependence that rely on nonparametric estimation of densities or multivariate integration, our autocorrelograms are simple to calculate and appear to work well in relatively small samples.
Evaluating, Comparing and Combining Density Forecasts Using the KLIC with an Application to the Bank of England and NIESR ‘Fan’ Charts of Inflation*
Authors: Mitchell James , Hall Stephen G.
Published: December 2005

This paper proposes and analyses the Kullback–Leibler information criterion (KLIC) as a unified statistical tool to evaluate, compare and combine density forecasts. Use of the KLIC is particularly attractive, as well as operationally convenient, given its equivalence with the widely used Berkowitz likelihood ratio test for the evaluation of individual density forecasts that exploits the probability integral transforms. Parallels with the comparison and combination of point forecasts are made. This and related Monte Carlo experiments help draw out properties of combined density forecasts. We illustrate the uses of the KLIC in an application to two widely used published density forecasts for UK inflation, namely the Bank of England and NIESR ‘fan’ charts.
International venture capital research: From cross‐country comparisons to crossing borders
Authors: Wright Mike , Pruthi Sarika , Lockett Andy
Published: December 2005

Venture capital (VC) has become an international phenomenon, and VC firms are a specific kind of service firm whose characteristics have distinctive implications for international behaviour. There is now a disparate body of research on international aspects of VC across a number of disciplines comprising finance, economics, strategy, entrepreneurship, international business and economic geography. A novel aspect of this paper is that we review and synthesize this disparate literature. A number of research gaps and limitations in the theoretical and methodological approaches involved in previous studies are identified and suggestions made for further research. We show that the vast majority of the literature relates to cross‐country comparisons; that is, macro‐level comparisons of VC industries across different countries and micro‐level comparisons of VC behaviour across countries. From our review of the literature, we argue that an under‐researched area concerns the influence of institutional contexts, especially the role of social networks and cultures. Furthermore, our review of the literature indicates that there is a major research gap in relation to work dealing with the crossing of country borders by VC firms. We suggest that resource‐based, capabilities, institutional and network theories may be offer insights to further our understanding of the behaviour of VC firms in this area.
Mitochondrial Dysfunction and Migraine
Authors: Sparaco M , Feleppa M , Lipton RB , Rapoport AM , Bigal ME
Published: December 2005

The molecular basis of migraine is still not completely understood. An impairment of mitochondrial oxidative metabolism might play a role in the pathophysiology of this disease, by influencing neuronal information processing. Biochemical assays of platelets and muscle biopsies performed in migraine sufferers have shown a decreased activity of the respiratory chain enzymes. Studies with phosphorus magnetic resonance spectroscopy (31P-MRS) have demonstrated an impairment of the brain oxidative energy metabolism both during and between migraine attacks. However, molecular genetic studies have not detected specific mitochondrial DNA (mtDNA) mutations in patients with migraine, although other studies suggest that particular genetic markers (i.e. neutral polymorphisms or secondary mtDNA mutations) might be present in some migraine sufferers. Further studies are still needed to clarify if migraine is associated with unidentified mutations on the mtDNA or on nuclear genes that code mitochondrial proteins. In this paper, we review morphological, biochemical, imaging and genetic studies which bear on the hypothesis that migraine may be related to mitochondrial dysfunction at least in some individuals.
NG2‐expressing cells as oligodendrocyte progenitors in the normal and demyelinated adult central nervous system
Authors: Polito Annabella , Reynolds Richard
Published: December 2005

The mammalian adult central nervous system (CNS) is known to respond rapidly to demyelinating insults by regenerating oligodendrocytes for remyelination from a dividing precursor population. A widespread population of cells exists within the adult CNS that is thought to belong to the oligodendrocyte lineage, but which do not express proteins characteristic of mature myelinating oligodendrocytes, such as myelin basic protein (MBP) and 2,3‐cyclic nucleotide 3‐phosphodiesterase (CNP). Instead, these cells have phenotypic characteristics of a more immature stage of the oligodendrocyte lineage. They express the NG2 chondroitin sulphate proteoglycan, in addition to O4 and the platelet‐derived growth factor α‐receptor, all widely accepted as markers for oligodendrocyte progenitor cells (OPCs) throughout development. However, NG2+ cells residing in the adult CNS do not resemble embryonic or neonatal NG2+ cells in terms of their morphology or proliferation characteristics, but instead represent a unique type of glial cell that has the ability to react rapidly to CNS damage. In this review, we present the evidence that adult NG2+ cells are part of the oligodendrocyte lineage and are capable of giving rise to new oligodendrocytes under both normal and demyelinating conditions. We also review the literature that these cells may have multiple functional roles within the adult CNS, notwithstanding their primary role as OPCs.
Synantocytes: the fifth element
Authors: Butt Arthur M. , Hamilton Niki , Hubbard Paul , Pugh Mari , Ibrahim Merdol
Published: December 2005

Classic studies have recognized neurons and three glial elements in the central nervous system (CNS) – astrocytes, oligodendrocytes and microglia. The identification of novel glia that specifically express the NG2 chondroitin sulphate proteoglycan (CSPG) raises the possibility of a fifth element. Until recently, all NG2‐expressing glia were considered to be oligodendrocyte precursor cells (OPCs) that persist in the adult CNS to generate oligodendrocytes throughout life. However, this narrow view of the function of ‘NG2‐glia’ is being challenged. The majority of NG2‐expressing glia in the adult CNS are a distinct class of cells that we have called ‘synantocytes’ (from the Greek synanto for contact). Synantocytes are stellate cells, with large process arborizations, and are exquisitely related to neurons. Individual cells traverse white and grey matter and form multiple contacts with neurons, astrocytes, oligodendrocytes and myelin. Synantocytes are an integral component of the ‘tetrapartite’ synapse, and provide a potential integrative neuron‐glial communications pathway. Neuronal activity, glutamate and adenosine triphosphate (ATP) act on synantocyte receptors and evoke raised intracellular calcium. It remains to be seen whether this serves a physiological function, but synantocytes may be specialized to monitor signals from neurons and glia, and to respond to changes in the integrity of the CNS via their specific contacts and ion channel and receptor profiles. The general consequences of synantocyte activation are proliferation and phenotypic changes, resulting in glial scar formation, or regeneration of oligodendrocytes, and possibly neurons.
Ultrastructural changes in the interhaemal membrane and junctional zone of the murine chorioallantoic placenta across gestation
Authors: Coan P. M. , Ferguson‐Smith A. C. , Burton G. J.
Published: December 2005

The mouse is an extremely useful experimental model for the study of human disease owing to the ease of genetic and physiological manipulation. A more detailed knowledge of murine placental development will, we hope, increase our understanding of the pathogenesis of placentally related complications of human pregnancy. The murine placenta consists of two main fetally derived compartments: the labyrinthine zone and the junctional zone. Exchange in the labyrinthine zone takes place across an interhaemal membrane comprising an outer layer of cytotrophoblast cells and two inner layers of syncytial trophoblast. The cytotrophoblast layer thins as gestation advances, and in addition becomes highly perforated after embryonic day (E)12.5. Furthermore, as gestation advances cytotrophoblast nuclear volume and DNA content increase, suggesting the formation of labyrinthine trophoblast giant cells. The syncytial layers become increasingly microvillous, enlarging the surface area for exchange. Separate basement membranes support the syncytium and the fetal capillary endothelium throughout gestation, although these appear to fuse where the capillaries are closely approximated to the trophoblast. The junctional zone consists of two principal trophoblast cell types, spongiotrophoblasts and invasive glycogen cells, yet the functions of each remain elusive. Spongiotrophoblasts vary in their appearance even when not fully differentiated, but a striking feature is the extensive endoplasmic reticulum of the more mature cells. Early glycogen cells are distinguished by the presence of electron‐dense glycogen granules, and large amounts of surrounding extracellular matrix. Later the accumulations of glycogen granules occupy almost all the cytoplasm and there are few organelles. This is the first study to use both scanning and transmission electron microscopy in an ultrastructural description of murine placental development and is complementary to contemporary genetic investigations.
Astrocytes and NG2‐glia: what's in a name?
Authors: Nishiyama Akiko , Yang Zhongshu , Butt Arthur
Published: December 2005

Classic studies recognize two functionally segregated macroglial cell types in the central nervous system (CNS), namely astrocytes and oligodendrocytes. A third macroglial cell type has now been identified by its specific expression of the NG2 chondroitin sulphate proteoglycan (NG2‐glia). These NG2‐glia exist abundantly in both grey and white matter of the mature CNS and are almost as numerous as astrocytes. It is well established that NG2‐glia give rise to oligodendrocytes. However, the majority of NG2‐glia in the adult CNS proliferate very slowly and are non‐motile. Both astrocytes and NG2‐glia display a stellate morphology and express ion channels and receptors to neurotransmitters used by neurons. Both types of glia make intimate contacts with neurons in grey and white matter, and their functional differences and similarities are only beginning to be unravelled. Recent observations emphasize the need to examine the relationship between astrocytes and NG2‐glia, and address the question of whether they represent overlapping or two distinct glial cell populations. To be of any relevance, this classification must relate to specific functions in the neural network. At present, the balance of evidence is that NG2‐glia and astrocytes are functionally segregated populations.
Fetal programming of fat and collagen in porcine skeletal muscles
Authors: Karunaratne J. F. , Ashton C. J. , Stickland N. C.
Published: December 2005

Connective tissue plays a key role in the scaffolding and development of skeletal muscle. Pilot studies carried out in our laboratory have shown that the smallest porcine littermate has a higher content of connective tissue within skeletal muscle compared with its largest littermate. The present study investigated the prenatal development of intralitter variation in terms of collagen content within connective tissue and intramuscular fat of the M. semitendinosus. Twenty‐three pairs of porcine fetuses from a Large White–Landrace origin were used aged from 36 to 86 days of gestation. The largest and smallest littermates were chosen by weight and the M. semitendinosus was removed from each. Complete transverse muscle sections were stained with Oil Red O (detection of lipids) and immunocytochemistry was performed using an antibody to collagen I. Slides were analysed and paired t‐Tests revealed the smallest littermate contained a significantly higher proportion of fat deposits and collagen I content compared with the largest littermate. Recent postnatal studies showing elevated levels of intramuscular lipids and low scores for meat tenderness in the smallest littermate corroborate our investigations. It can be concluded that the differences seen in connective tissue elements have a fetal origin that may continue postnatally.
Overweight, obesity and the food service industry
Authors: Edwards John S. A. , Engström Katja , Hartwell Heather J.
Published: December 2005

In many countries people are eating out more often and the food service industry has encouraged/reacted to this with business activities such as ‘super‐sizing’, product bundling and ‘all you can eat buffets’. At the same time, the incidence of overweight and obesity has increased throughout the world and the food service industry has been implicated if not blamed entirely for this situation. However, is the food service industry rightly condemned as the obesity villain? This article considers some of the factors in the obesity debate and concludes that it is not a ‘one‐way street’ and both the food service industry and consumer alike bear responsibility for the current situation.
Allosteric modulation of anti‐HIV drug and ferric heme binding to human serum albumin
Authors: Bocedi Alessio , Notari Stefania , Menegatti Enea , Fanali Gabriella , Fasano Mauro , Ascenzi Paolo
Published: December 2005

Human serum albumin (HSA), the most prominent protein in plasma, is best known for its exceptional capacity to bind ligands (e.g. heme and drugs). Here, binding of the anti‐HIV drugs abacavir, atazanavir, didanosine, efavirenz, emtricitabine, lamivudine, nelfinavir, nevirapine, ritonavir, saquinavir, stavudine, and zidovudine to HSA and ferric heme–HSA is reported. Ferric heme binding to HSA in the absence and presence of anti‐HIV drugs was also investigated. The association equilibrium constant and second‐order rate constant for the binding of anti‐HIV drugs to Sudlow's site I of ferric heme–HSA are lower by one order of magnitude than those for the binding of anti‐HIV drugs to HSA. Accordingly, the association equilibrium constant and the second‐order rate constant for heme binding to HSA are decreased by one order of magnitude in the presence of anti‐HIV drugs. In contrast, the first‐order rate constant for ligand dissociation from HSA is insensitive to anti‐HIV drugs and ferric heme. These findings represent clear‐cut evidence for the allosteric inhibition of anti‐HIV drug binding to HSA by the heme. In turn, anti‐HIV drugs allosterically impair heme binding to HSA. Therefore, Sudlow's site I and the heme cleft must be functionally linked.
Signalling and regulation of collagen I synthesis by ET‐1 and TGF‐β1
Authors: Horstmeyer Angelika , Licht Christoph , Scherr Gabriele , Eckes Beate , Krieg Thomas
Published: December 2005

Endothelin‐1 (ET‐1) plays an important role in tissue remodelling and fibrogenesis by inducing synthesis of collagen I via protein kinase C (PKC). ET‐1 signals are transduced by two receptor subtypes, the ETA‐ and ETB‐receptors which activate different Gα proteins. Here, we investigated the expression of both ET‐receptor subtypes in human primary dermal fibroblasts and demonstrated that the ETA‐receptor is the major ET‐receptor subtype expressed. To determine further signalling intermediates, we inhibited Gαi and three phospholipases. Pharmacologic inhibition of Gαi, phosphatidylcholine‐phospholipase C (PC‐PLC) and phospholipase D (PLD), but not of phospholipase Cβ, abolished the increase in collagen I by ET‐1. Inhibition of all phospholipases revealed similar effects on TGF‐β1 induced collagen I synthesis, demonstrating involvement of PC‐PLC and PLD in the signalling pathways elicited by ET‐1 and TGF‐β1. ET‐1 and TGF‐β1 each stimulated collagen I production and in an additive manner. ET‐1 further induced connective tissue growth factor (CTGF), as did TGF‐β1, however, to lower levels. While rapid and sustained CTGF induction was seen following TGF‐β1 treatment, ET‐1 increased CTGF in a biphasic manner with lower induction at 3 h and a delayed and higher induction after 5 days of permanent ET‐1 treatment. Coincidentally at 5 days of permanent ET‐1 stimulation, a switch in ET‐receptor subtype expression to the ETB‐receptor was observed. We conclude that the signalling pathways induced by ET‐1 and TGF‐β1 leading to augmented collagen I production by fibroblasts converge on a similar signalling pathway. Thereby, long‐time stimulation by ET‐1 resulted in a changed ET‐receptor subtype ratio and in a biphasic CTGF induction.
Lipopeptide structure determines TLR2 dependent cell activation level
Authors: Buwitt‐Beckmann Ute , Heine Holger , Wiesmüller Karl‐Heinz , Jung Günther , Brock Roland , Ulmer Artur J
Published: December 2005

Bacterial lipoproteins/peptides are composed of di‐O‐acylated‐S‐(2,3‐dihydroxypropyl)‐cysteinyl residues N‐terminally coupled to distinct polypeptides, which can be N‐acylated with a third fatty acid. Using a synthetic lipopeptide library we characterized the contribution of the lipid portion to the TLR2 dependent pattern recognition. We found that the two ester bound fatty acid length threshold is beyond eight C atoms because almost no response was elicited by cellular challenge with analogues carrying shorter acyl chains in HEK293 cells expressing recombinant human TLR2. In contrast, the amide bound fatty acid is of lesser importance. While two ester‐bound palmitic acids mediate a high stimulatory activity of the respective analogue, a lipopeptide carrying one amide‐bound and another ester‐bound palmitic acid molecule was inactive. In addition, species specific LP recognition through murine and human TLR2 depended on the length of the two ester bound fatty acid chains. In conclusion, our results indicate the responsibility of both ester bound acyl chains but not of the amide bound fatty acid molecule for the TLR dependent cellular recognition of canonical triacylated LP, as well as a requirement for a minimal acyl chain length. Thus they might support the explanation of specific immuno‐stimulatory potentials of different microorganisms and provide a basis for rational design of TLR2 specific adjuvants mediating immune activation to distinct levels.
A FYVE‐containing unusual cyclic nucleotide phosphodiesterase from Trypanosoma cruzi
Authors: Kunz Stefan , Oberholzer Michael , Seebeck Thomas
Published: December 2005

Cyclic‐nucleotide‐specific phosphodiesterases (PDEs) are key players in the intracellular signaling pathways of the important human pathogen Trypanosoma cruzi. We report herein the identification of an unusual PDE from this protozoal organism. This enzyme, TcrPDEC, is a member of the class I PDEs, as determined from the presence of a characteristic signature sequence and from the conservation of a number of functionally important amino acid residues within its catalytic domain. Class I PDEs include a large number of PDEs from eukaryotes, among them all 11 human PDE families. Unusually for an enzyme of this class, TcrPDEC contains a FYVE‐type domain in its N‐terminal region, followed by two closely spaced coiled‐coil domains. Its catalytic domain is located in the middle of the polypeptide chain, whereas all other class I enzymes contain their catalytic domains in their C‐terminal parts. TcrPDEC can complement a PDE‐deficient yeast strain. Unexpectedly for a kinetoplastid PDE, TcrPDEC is a dual‐specificity PDE that accepts both cAMP and cGMP as its substrates.
The Neural Matrix of Pain Processing and Placebo Analgesia: Evidence from Functional Imaging
Authors: Tracey Irene
Published: December 2005

Recent functional imaging studies in humans have given us unprecedented opportunities to define the neuroanatomical basis for the placebo effect. Though these studies have largely been conducted in the field of pain and analgesia, the findings could well provide models for more general placebo effects in other clinical situations. Key regions that mediate the placebo effect include prefrontal cortices, anterior cingulate cortex (ACC) and brainstem structures, whereas the specific analgesic effects produced subsequent to a placebo response are mediated by a decreased activation in key pain processing brain regions, similar to that seen via pharmacological means. These new methods provide powerful tools with which to study the placebo response in pain and other diseases as they allow correlations to be made between cognitive manipulations and behavioral outcomes with changes in functionally defined neuroanatomical brain regions. Researchers are harnessing these methods to construct generalized models for the placebo effect that can be tested beyond the field of pain and analgesia.
The lifetime of grand design
Authors: Merrifield M. R. , Rand R. J. , Meidt S. E.
Published: December 2005

The lifetime of the structure in grand design spiral galaxies is observationally ill-determined, but is essentially set by how accurately the rotation of the pattern can be characterized by a single angular pattern speed. This paper derives a generalized version of the Tremaine–Weinberg method for observationally determining pattern speeds, in which the pattern speed is allowed to vary arbitrarily with radius. The departures of the derived pattern speed from a constant then provide a simple metric of the lifetime of the spiral structure. Application of this method to CO observations of NGC 1068 reveals that the pattern speed of the spiral structure in this galaxy varies rapidly with radius, and that the lifetime of the spiral structure is correspondingly very short. If this result turns out to be common in grand-design spiral galaxies, then these features will have to be viewed as highly transient phenomena.