bluuebunny/crossref_metadata_2025 huggingface dataset:
In silico and microarray-based genomic approaches to identifying potential vaccine candidates against Leptospira interrogans
Authors: Yang Hong-Liang , Zhu Yong-Zhang , Qin Jin-Hong , He Ping , Jiang Xu-Cheng , Zhao Guo-Ping , Guo Xiao-Kui
Published: November 2006

Background

Currently available vaccines against leptospirosis are of low efficacy, have an unacceptable side-effect profile, do not induce long-term protection, and provide no cross-protection against the different serovars of pathogenic leptospira. The current major focus in leptospirosis research is to discover conserved protective antigens that may elicit longer-term protection against a broad range ofLeptospira. There is a need to screen vaccine candidate genes in the genome ofLeptospira interrogans.

Results

Bioinformatics, comparative genomic hybridization (CGH) analysis and transcriptional analysis were used to identify vaccine candidates in the genome ofL. interrogansserovar Lai strain #56601. Of a total of 4727 open reading frames (ORFs), 616 genes were predicted to encode surface-exposed proteins by P-CLASSIFIER combined with signal peptide prediction, α-helix transmembrane topology prediction, integral β-barrel outer membrane protein and lipoprotein prediction, as well as by retaining the genes shared by the two sequencedL. interrogansgenomes and by subtracting genes with human homologues. A DNA microarray ofL. interrogansstrain #56601 was constructed for CGH analysis and transcriptome analysisin vitro. Three hundred and seven differential genes were identified in ten pathogenic serovars by CGH; 1427 genes had high transcriptional levels (Cy3 signal ≥ 342 and Cy5 signal ≥ 363.5, respectively). There were 565 genes in the intersection between the set encoding surface-exposed proteins and the set of 307 differential genes. The number of genes in the intersection between this set of 565 and the set of 1427 highly transcriptionally active genes was 226. These 226 genes were thus identified as putative vaccine candidates. The proteins encoded by these genes are not only potentially surface-exposed in the bacterium, but also conserved in two sequencedL. interrogans. Moreover, these genes are conserved among ten epidemic serovars in China and have high transcriptional levelsin vitro.

Conclusion

Of the 4727 ORFs in the genome ofL. interrogans, 226 genes were identified as vaccine candidates by bioinformatics, CGH and transcriptional analysis on the basis of the theory of reverse vaccinology. The proteins encoded by these genes might be useful as vaccine candidates as well as for diagnosis of leptospirosis.
Determinants for receiving acupuncture for LBP and associated treatments: a prospective cohort study
Authors: Chenot Jean-François , Becker Annette , Leonhardt Corinna , Keller Stefan , Donner-Banzhoff Norbert , Baum Erika , Pfingsten Michael , Hildebrandt Jan , Kochen Michael M , Basler Heinz-Dieter
Published: November 2006

Background

Acupuncture is a frequently used but controversial adjunct to the treatment of chronic low back pain (LBP). Acupuncture is now considered to be effective for chronic LBP and health care systems are pressured to make a decision whether or not acupuncture should be covered. It has been suggested that providing such services might reduce the use of other health care services. Therefore, we explored factors associated with acupuncture treatment for LBP and the relation of acupuncture with other health care services.

Methods

This is a post hoc analysis of a longitudinal prospective cohort study. General practitioners (GPs) recruited consecutive adult patients with LBP. Data on physical function, subjective mood and utilization of health care services was collected at the first consultation and at follow-up telephone interviews for a period of twelve months.

Results

A total of 179 (13 %) out of 1,345 patients received acupuncture treatment. The majority of those (59 %) had chronic LBP. Women and elderly patients were more likely to be given acupuncture. Additional determinants of acupuncture therapy were low functional capacity and chronicity of pain. Chronic (vs. acute) back pain OR 1.6 (CL 1.4–2.9) was the only significant disease-related factor associated with the treatment. The strongest predictors for receiving acupuncture were consultation with a GP who offers acupuncture OR 3.5 (CL 2.9–4.1) and consultation with a specialist OR 2.1 (CL 1.9–2.3). After adjustment for patient characteristics, acupuncture remained associated with higher consultation rates and an increased use of other health care services like physiotherapy.

Conclusion

Receiving acupuncture for LBP depends mostly on the availability of the treatment. It is associated with increased use of other health services even after adjustment for patient characteristics. In our study, we found that receiving acupuncture does not offset the use of other health care resources. A significant proportion of patients who received did not meet the so far only known selection criterion (chonicity). Acupuncture therapy might be a reflection of helplessness in both patients and health care providers.
CXCL1/KC and CXCL5/LIX are selectively produced by corneal fibroblasts and mediate neutrophil infiltration to the corneal stroma in LPS keratitis
Authors: Lin Michelle , Carlson Eric , Diaconu Eugenia , Pearlman Eric
Published: November 2006

The severity of corneal inflammation depends on the activity of infiltrating neutrophils responding to chemotactic factors such as CXC chemokines. This study examines the relative contribution of CXCL1/keratinocyte-derived chemokine (KC), CXCL2/monocyte-inhibitory protein-2 (MIP-2), and CXCL5/LPS-induced chemokine (LIX) in neutrophil recruitment to the corneal stroma during LPS keratitis, where neutrophils infiltrate the corneal stroma at 6 h after LPS injection and peak at 24 h. Consistent with this timeframe, KC was detected after 3 h, reached peak levels at 24 h, and decreased thereafter. In contrast, LIX production was not detected until 8 h after injection and peaked at 24 h. MIP-2 was detected at 3 h but did not reach the levels of KC and LIX. Cell types associated with corneal inflammation produced markedly different chemokines in vitro: Murine corneal fibroblasts (MK/T-1) produced LIX and KC in response to LPS but did not produce MIP-2, whereas peritoneal macrophages and neutrophils produced MIP-2 and KC but did not produce LIX. To determine the role of these chemokines in neutrophil recruitment to the cornea, anti-LIX, anti-KC, or anti-MIP-2 was injected into the corneal stroma of enhanced GFP chimeric mice prior to LPS, and total cell and neutrophil infiltration was examined. Antibody to LIX and KC, injected individually or in combination, significantly inhibited neutrophil recruitment to the cornea, whereas anti-MIP-2 had no inhibitory effect. Together, these findings demonstrate cell-specific production of CXC chemokines and show that LIX and KC mediate neutrophil recruitment into the cornea during LPS keratitis.
Characterization of CD8+ T cell repertoire in identical twins discordant and concordant for multiple sclerosis
Authors: Somma Paolo , Ristori Giovanni , Battistini Luca , Cannoni Stefania , Borsellino Giovanna , Diamantini Adamo , Salvetti Marco , Sorrentino Rosa , Fiorillo Maria Teresa
Published: November 2006

Autoreactive CD4+ and CD8+ T cells directed against CNS autoantigens may play a role in the development of multiple sclerosis (MS). Identical twins share the same genetic background but not the TCR repertoire that is shaped by the encounter with self or foreign antigens. To gain insights into the interplay between MS and T cell repertoire, peripheral blood CD4+ and CD8+ T lymphocytes and their CCR7+/CCR7– subsets from five pairs of identical twins (four discordant and one concordant for MS; none of which had taken disease-modifying therapy) were compared by TCR β-chain (TCRB) complementary-determining region 3 (CDR3) spectratyping. CD4+ T cells generally showed a Gaussian distribution, whereas CD8+ T cells exhibited subject-specific, widely skewed TCR spectratypes. There was no correlation between CD8+ T cell oligoclonality and disease. Sequencing of predominant spectratype expansions revealed shared TCRB-CDR3 motifs when comparing inter- and/or intrapair twin members. In many cases, these sequences were homologous to published TCRs, specific for viruses implicated in MS pathogenesis, CNS autoantigens, or copaxone [glatiramer acetate (GA)], implying the occurrence of naturally GA-responding CD8+ T cells. It is notable that these expanded T cell clones with putative pathogenic or regulatory properties were present in the affected as well as in the healthy subject, thus suggesting the existence of a “MS predisposing trait” shared by co-twins discordant for MS.
Neuromedin S as Novel Putative Regulator of Luteinizing Hormone Secretion
Authors: Vigo E. , Roa J. , López M. , Castellano J. M. , Fernandez-Fernandez R. , Navarro V. M. , Pineda R. , Aguilar E. , Diéguez C. , Pinilla L. , Tena-Sempere M.
Published: November 2006

Neuromedin S (NMS), a 36 amino acid peptide structurally related to neuromedin U, was recently identified in rat brain as ligand for the G protein-coupled receptor FM4/TGR-1, also termed neuromedin U receptor type-2 (NMU2R). Central expression of NMS appears restricted to the suprachiasmatic nucleus, and NMS has been involved in the regulation of dark-light rhythms and suppression of food intake. Reproduction is known to be tightly regulated by metabolic and photoperiodic cues. Yet the potential contribution of NMS to the control of reproductive axis remains unexplored. We report herein analyses of hypothalamic expression of NMS and NMU2R genes, as well as LH responses to NMS, in different developmental and functional states of the female rat. Expression of NMS and NMU2R genes was detected at the hypothalamus along postnatal development, with significant fluctuations of their relative levels (maximum at prepubertal stage and adulthood). In adult females, hypothalamic expression of NMS (which was confined to suprachiasmatic nucleus) and NMU2R significantly varied during the estrous cycle (maximum at proestrus) and was lowered after ovariectomy and enhanced after progesterone supplementation. Central administration of NMS evoked modest LH secretory responses in pubertal and cyclic females at diestrus, whereas exaggerated LH secretory bursts were elicited by NMS at estrus and after short-term fasting. Conversely, NMS significantly decreased elevated LH concentrations of ovariectomized rats. In summary, we provide herein novel evidence for the ability of NMS to modulate LH secretion in the female rat. Moreover, hypothalamic expression of NMS and NMU2R genes appeared dependent on the functional state of the female reproductive axis. Our data are the first to disclose the potential implication of NMS in the regulation of gonadotropic axis, a function that may contribute to the integration of circadian rhythms, energy balance, and reproduction.
Placental Restriction of Fetal Growth Increases Insulin Action, Growth, and Adiposity in the Young Lamb
Authors: De Blasio Miles J. , Gatford Kathryn L. , McMillen I. Caroline , Robinson Jeffrey S. , Owens Julie A.
Published: November 2006

Most children who are short or light at birth due to intrauterine growth restriction (IUGR) exhibit accelerated growth in infancy, termed “catch-up” growth, which together with IUGR, predicts increased risk of type 2 diabetes and obesity later in life. Placental restriction (PR) in sheep reduces size at birth, and also causes catch-up growth and increased adiposity at 6 wk of age. The physiological mechanisms responsible for catch-up growth after IUGR and its links to these adverse sequelae are unknown. Because insulin is a major anabolic hormone of infancy and its actions are commonly perturbed in these related disorders, we hypothesized that restriction of fetal growth would alter insulin secretion and sensitivity in the juvenile sheep at 1 month, which would be related to their altered growth and adiposity. We show that PR impairs glucose-stimulated insulin production, but not fasting insulin abundance or production in the young sheep. However, PR increases insulin sensitivity of circulating free fatty acids (FFAs), and insulin disposition indices for glucose and FFAs. Catch-up growth is predicted by the insulin disposition indices for amino acids and FFAs, and adiposity by that for FFAs. This suggests that catch-up growth and early-onset visceral obesity after IUGR may have a common underlying cause, that of increased insulin action due primarily to enhanced insulin sensitivity, which could account in part for their links to adverse metabolic and related outcomes in later life.
Intestinal Resistance to 1,25 Dihydroxyvitamin D in Mice Heterozygous for the Vitamin D Receptor Knockout Allele
Authors: Song Yurong , Fleet James C.
Published: November 2006

We tested the hypothesis that low vitamin D receptor (VDR) level causes intestinal vitamin D resistance and intestinal calcium (Ca) malabsorption. To do so, we examined vitamin D regulated duodenal Ca absorption and gene expression [transient receptor potential channel, vallinoid subfamily member 6 (TRPV6), 24-hydroxylase, calbindin D9k (CaBP) mRNA, and CaBP protein] in wild-type mice and mice with reduced tissue VDR levels [i.e. heterozygotes for the VDR gene knockout (HT)]. Induction of 24-hydroxylase mRNA levels by 1,25 dihydroxyvitamin D3 [1,25(OH)2 D3] injection was significantly reduced in the duodenum and kidney of HT mice in both time-course and dose-response experiments. TRPV6 and CaBP mRNA levels in duodenum were significantly induced after 1,25(OH)2 D3 injection, but there was no difference in response between wild-type and HT mice. Feeding a low-calcium diet for 1 wk increased plasma PTH, renal 1α-hydroxylase (CYP27B1) mRNA level, and plasma 1,25(OH)2 D3, and this response was greater in HT mice (by 88, 55, and 37% higher, respectively). In contrast, duodenal TRPV6 and CaBP mRNA were not higher in HT mice fed the low-calcium diet. However, the response of duodenal Ca absorption and CaBP protein to increasing 1,25(OH)2 D3 levels was blunted by 40% in HT mice. Our data show that low VDR levels lead to resistance of intestinal Ca absorption to 1,25(OH)2 D3, and this resistance may be due to a role for the VDR (and VDR level) in the translation of CaBP.
Protein Kinase Cζ Is Required for Oleic Acid-Induced Secretion of Glucagon-Like Peptide-1 by Intestinal Endocrine L Cells
Authors: Iakoubov Roman , Izzo Angelo , Yeung Andrea , Whiteside Catharine I. , Brubaker Patricia L.
Published: November 2006

Long-chain, monounsaturated fatty acids (FAs) stimulate secretion of the incretin hormone, glucagon-like peptide-1 (GLP-1) from the intestinal L cell. Because the atypical protein kinase C (PKC), PKCζ, is involved in FA signaling in many cells, the role of PKCζ in FA-induced GLP-1 secretion was investigated, using the murine GLUTag L cell line and primary rat intestinal L cells. GLUTag cells expressed mRNA for several PKC isoforms, including PKCζ, and PKCζ protein was localized throughout the cytoplasm in GLUTag and primary L cells as well as normal mouse and rat L cells. Treatment with oleic acid (150–1000 μm) for 2 h increased GLP-1 secretion (P < 0.001), and this was abrogated by the PKCζ inhibitor ZI (P < 0.05) and PKCζ small interfering RNA transfection (P < 0.05) but not inhibition of classical/novel PKC isoforms. Although most PKCζ was localized in the particulate compartment of GLUTag cells, oleate treatment did not alter PKCζ levels or activity in this cell fraction. GLUTag cells expressed mRNA for the Gq-coupled FA receptor GPR120; however, oleic acid did not induce any changes in Akt, MAPK, or calcium, and pretreatment with LY294002 and PD98059 to inhibit phosphatidylinositol 3-kinase and MAPK, respectively, did not prevent the effects of oleic acid. Finally, GLUTag cells also released GLP-1 in response to arachidonic acid (P < 0.001) but were not affected by other long-chain FAs. These findings demonstrate that PKCζ is required for oleic acid-induced GLP-1 secretion. This enzyme may therefore serve as a therapeutic target to enhance GLP-1 release in type 2 diabetes.
Jumping performance of froghopper insects
Authors: Burrows Malcolm
Published: November 2006

The kinematics of jumping in froghopper insects were analysed from high speed sequences of images captured at rates up to 8000 s-1. In a jump, the attitude of the body is set by the front and middle legs, and the propulsion is delivered by rapid and synchronous movements of the hind legs that are 1.5 times longer than the other legs, but are only about half the length of the body and represent just 2% of the body mass. The wings are not moved and the front and middle legs may be raised off the ground before take-off. The hind legs are first cocked by a slow levation of the trochantera about the coxae so that the femora are pressed against the ventral, indented wall of the thorax, with the femoro-tibial joints tucked between the middle legs and body. Only the tips of the hind tarsi are in contact with the ground. In this position, the hind legs stay motionless for 1-2 s. Both trochantera are then synchronously and rapidly depressed about the coxae at rotational velocities of 75 500 deg. s-1 and the tibiae extended, to launch a jump that in Philaenus reaches a height of 700 mm, or 115 body lengths.

In the best jumps by Philaenus, take-off occurs within 0.875 ms of the start of movements of the hind legs at a peak velocity of 4.7 m s-1 and involves an acceleration of 5400 m s-2,equivalent to 550 times gravity. This jumping performance requires an energy output of 136 μJ, a power output of 155 mW and exerts a force of 66 mN.
Regulation of troponin T expression during muscle development in sea breamSparus auratusLinnaeus: the potential role of thyroid hormones
Authors: Campinho M. A. , Sweeney G. E. , Power D. M.
Published: November 2006

In the sea bream Sparus auratus three stage-specific fast troponin T (fTnT) isoforms have been cloned and correspond to embryonic-, larval- and adult-specific isoforms. Characterisation, using database searches, of the putative genomic organisation of Fugu rubripes and Tetraodon nigroviridis fTnT indicates that alternative exon splicing in the 5 region of the gene generates the different isoforms. Moreover, comparison of teleost fTnTs suggests that alternative splicing of fTnT appears to be common in teleosts. A different temporal expression pattern for each fTnT splice varotnt is found during sea bream development and probably relates to differing functional demands, as a highly acidic embryonic form (pI 5.16) is substituted by a basic larval form (pI 9.57). Thyroid hormones (THs), which play an important regulatory role in muscle development in flatfish and tetrapods,appear also to influence TnT gene expression in the sea bream. However, THs have a divergent action on different sea bream TnT genes and although the slow isoform (sTnT1) is TH-responsive, fTnT, sTnT2 and the itronless isoform (iTnT) are unaffected. The present results taken together with those published for flatfish seem to suggest differences may exist in the regulation of larval muscle development in teleosts.
Neural control of the velum in larvae of the gastropod,Ilyanassa obsoleta
Authors: Braubach Oliver R. , Dickinson Amanda J. G. , Evans Carol C. E. , Croll Roger P.
Published: November 2006

Larval molluscs commonly use ciliated vela to swim and feed. In this study we used immunohistochemistry to demonstrate innervation of velar cilia and muscles by monoaminergic and peptidergic fibres in the caenogastropod, Ilyanassa obsoleta. Photoelectric recordings from pre-oral cilia on isolated pieces of velum revealed that serotonin increased, whereas catecholamines (dopamine and norepinephrine) decreased beat frequency at concentrations of 10-6 to 10-9 mol l-1. Catecholamines also increased the frequency of momentary, isolated arrests of pre-oral cilia, but failed to suppress beating of the post-oral cilia at these concentrations. The neuropeptides, FMRFamide and Leu-enkephalin, did not affect the frequency of ciliary beating or of isolated ciliary arrests, but did induce numerous muscular contractions, which were accompanied by sustained ciliary arrests. In terms of whole animal behaviour, serotonin caused larvae to concentrate toward the top of a water column and to increase feeding,whereas catecholamines caused larvae to concentrate toward the bottom of a water column and decrease feeding. Monoamine analogues which facilitated or opposed the effects of synthetic transmitters on larval behaviour, further suggested that these transmitters are released endogenously to control velar function. Finally, applications of peptides to whole larvae caused increased frequency of locomotory arrests. Together these findings demonstrate several potential roles for the nervous system in controlling larval behaviour in gastropods.
Fooling a freshwater fish: how dietary salt transforms the rainbow trout gill into a seawater gill phenotype
Authors: Perry Steve F. , Rivero-Lopez Luis , McNeill Brian , Wilson Jonathan
Published: November 2006

Numerous fish species, including rainbow trout (Oncorhynchus mykiss), are able to inhabit both freshwater and seawater and routinely migrate between the two environments. One of the most critical adjustments allowing such successful migrations is a remodelling of the gill in which a suite of morphological and molecular changes ensure optimal function in the face of reversing requirements for salt and water balance. The remodelling leads to specific freshwater and seawater gill phenotypes that are readily identified by the orientation and/or quantities of specific ion transporters and the presence or absence of specific cell types. The proximate cues promoting gill phenotypic plasticity are unknown. Here, by assessing the consequences of a salt-enriched diet (in the absence of any changes in external salinity) in the freshwater rainbow trout, we demonstrate that internal salt loading alone, is able to induce various elements of the seawater gill phenotype. Specifically, we show upregulation of three ion transport genes, cystic fibrosis transmembrane conductance regulator (CFTR),Na+/K+/2Cl- co-transporter (NKCC1) and Na+/K+-ATPase, which are essential for ionic regulation in seawater, and the appearance of chloride cell-accessory cell complexes,which are normally restricted to fish inhabiting seawater. These data provide compelling evidence that gill remodelling during migration from freshwater to seawater may involve sensing of elevated levels of internal salt.
Path selection in cockroaches
Authors: Jeanson Raphaël , Deneubourg Jean-Louis
Published: November 2006

In gregarious insects, the exploration and the use of the home range can involve both individual navigational abilities and/or chemical trails. Trail formation can result from an active laying of pheromones but can also derive from the incidental deposition of chemical cues. In this study, we investigated whether scent trails can influence path selection in the cockroach Blattella germanica (L.). Experiments were designed to separate the role of prior experience based on the orientation of the path and the presence of trails. In a first phase, cockroaches were able to access freely one or two branches of a platform during a 48 h period. In a second phase, cockroaches were offered a binary choice between one marked and one clean branch, or between two clean branches. In the absence of trails,cockroaches prefer the novel orientation but in the presence of a trail previously laid by the same group of individuals, they prefer the path with the trail, irrespective of orientation. However, cockroaches tended to avoid trails laid by a different group of cockroaches. Overall, our results indicate that both scent cues and response to novelty influence, weakly but significantly, path selection in cockroaches. The plausible nature of scent marks used by cockroaches is discussed. Our study suggests that the influence of incident trailing cues can be modulated by learning to support a flexible orientation strategy depending on individual experience.
Photoperiod-induced plasticity of thermosensitivity and acquired thermotolerance inLocusta migratoria
Authors: Rodgers Corinne I. , Shoemaker Kelly L. , Robertson R. Meldrum
Published: November 2006

The mechanisms by which different life histories affect neural circuits are largely unknown. We show that the thermosensitivity and thermotolerance of neural circuit operation are affected in a complex dynamic fashion by photoperiod, prior heat experience and the sex of the animal. We compared thermosensitivity and thermotolerance of ventilatory motor pattern generation in locusts reared under two photoperiods (12:12 and 16:8; i.e. 12 h:12 h and 16 h:8 h L:D, respectively) before and after heat shock pre-treatment (HS: 3 h, 45°C) in order to determine the effect of daylength on properties of neural function. We monitored central pattern generator (CPG) output electromyographically from muscle 161 in the second abdominal segment during ramped increases in temperature and also measured the time taken for the circuit to fail at high temperatures and the time taken to recover on return to room temperature. There were effects of photoperiod, heat pre-treatment and the sex of the animal on ventilatory rate, time-to-failure and time-to-recovery. The ventilatory motor pattern of 16:8 and 12:12 locusts responded differently to increasing and maintained high temperature stress in both control and heat shocked locusts. We found that 12:12 locusts were generally more robust than 16:8 locusts: they lived longer, they showed greater tolerance to high temperatures, and they recovered more quickly from temperature-induced circuit failure. A faster ventilatory rate in 12:12 animals at high temperatures may have accelerated evaporative cooling to mediate improved temperature tolerance.
Interactions between the neural regulation of stress and aggression
Authors: Summers Cliff H. , Winberg Svante
Published: November 2006

Socially aggressive interaction is stressful. What is more, social aggression is stressful for both dominant and subordinate animals. Much of the neurocircuitry for stress and aggression overlap. The pattern of neurochemical and hormonal events stimulated by social interaction make it clear that subtle differences in this pattern of response distinguish social rank. The neurotransmitter serotonin (5-HT) responds rapidly to stress, and also appears to play the most important role for inhibitory regulation of aggressive interactions. In addition, the adrenocortical/interrenal steroid hormones corticosterone and cortisol are responsive to stress and influence aggression. However, while 5-HT and glucocorticoids can both be inhibitory to aggression,the relationship between 5-HT and glucocorticoids is not straightforward, and much of the distinctions in function depend upon timing. Neither is inhibitory during the early stressful phase of aggression. This transmitter-hormone combination follows and influences a four-stage functional pattern of effect:(1) predisposed (positively or negatively) toward aggression, (2) motivated toward behavior, (3) responsive to stress (including aggression) and passively allowing aggression, and finally (4) chronically applied 5-HT and glucocorticoids inhibit aggression.
Ontogeny of swim performance and mechanics in bottlenose dolphins(Tursiops truncatus)
Authors: Noren Shawn R. , Biedenbach George , Edwards Elizabeth F.
Published: November 2006

Morphological and physiological development impacts swimming performance throughout ontogeny. Our investigation of the ontogeny of swim performance(mean and maximum swim speed) and swim effort (stroke amplitude and tailbeat frequency) of independently swimming bottlenose dolphins (Tursiops truncatus) demonstrated that swimming capabilities are extremely limited in calves. Mean and maximum swim speeds of 0-1-month-old calves were only 37%and 52% of that for adults, respectively, and levels similar to those of adults were not achieved until one year post-partum. Limitations in swim speed were associated with an inability to achieve mature thrusting capabilities, as stroke amplitude and distance covered per stroke remained significantly lower than adult levels during the first-year post-partum. Although calves were expected to require less thrusting power to propel their smaller bodies through water, size-specific stroke amplitudes of 0-3-month-olds (23-26% of body length) were smaller than those of dolphins ≥10 months post-partum(29-30% of body length). As a result, swim speed standardized by body length was significantly slower for 0-3-month-old dolphins compared with dolphins≥10 months post-partum. These results suggest that other factors, such as underdeveloped physiology, act synergistically with small body size to limit independent swim performance in dolphins during ontogeny.
Cone photoreceptor oil droplet pigmentation is affected by ambient light intensity
Authors: Hart Nathan S. , Lisney Thomas J. , Collin Shaun P.
Published: November 2006

The cone photoreceptors of many vertebrates contain spherical organelles called oil droplets. In birds, turtles, lizards and some lungfish the oil droplets are heavily pigmented and function to filter the spectrum of light incident upon the visual pigment within the outer segment. Pigmented oil droplets are beneficial for colour discrimination in bright light, but at lower light levels the reduction in sensitivity caused by the pigmentation increasingly outweighs the benefits generated by spectral tuning. Consequently, it is expected that species with pigmented oil droplets should modulate the density of pigment in response to ambient light intensity and thereby regulate the amount of light transmitted to the outer segment. In this study, microspectrophotometry was used to measure the absorption spectra of cone oil droplets in chickens (Gallus gallus domesticus) reared under bright (unfiltered) or dim (filtered) sunlight. Oil droplet pigmentation was found to be dependent on the intensity of the ambient light and the duration of exposure to the different lighting treatments. In adult chickens reared in bright light, the oil droplets of all cone types (except the violet-sensitive single cones, whose oil droplet is always non-pigmented) were more densely pigmented than those in chickens reared in dim light. Calculations show that the reduced levels of oil droplet pigmentation in chickens reared in dim light would increase the sensitivity and spectral bandwidth of the outer segment significantly. The density of pigmentation in the oil droplets presumably represents a trade-off between the need for good colour discrimination and absolute sensitivity. This might also explain why nocturnal animals, or those that underwent a nocturnal phase during their evolution, have evolved oil droplets with low pigment densities or no pigmentation or have lost their oil droplets altogether.
Lack of generalization of object discrimination between spatial contexts by a bat
Authors: Stich Kai Petra , Winter York
Published: November 2006

Discrimination and generalization are important elements of cognition in the daily lives of animals. Nectar-feeding bats detect flowers by olfaction and probably vision, but also use echolocation and echo-perception of flowers in immediate target surroundings. The echo received from an interference-rich flower corolla is a function of a bat's own relative position in space. This raises the question how easily a free-flying bat will generalize an echo stimulus from a learning situation to a new spatial context where differences in relative flight approach trajectories may lead to an unfamiliar spectral composition of the self-generated echoes. We trained free-flying Glossophaga soricina in echoacoustic discrimination in a two-alternative forced-choice (2-AFC) paradigm at location A. We then tested at location B for spontaneous transfer of discrimination ability. Bats did not spontaneously transfer the discrimination ability acquired at A to location B. This lack of spontaneous generalization may have been caused by factors of the underlying learning mechanisms. 2-AFC tasks may not be representative of the natural foraging behaviour of flower-visiting bats. In contrast to insect-eating bats that constantly evaluate the environment to detect unpredictable prey, the spatial stability of flowers may allow flower visitors to rely on spatial memory to guide foraging. The 2-AFC task requires the disregard (learned irrelevance) of salient spatial location cues that are different at each new location. In Glossophaga, a conjunction between spatial context and 2-AFC discrimination learning may have inhibited the transfer of learned irrelevance of spatial location in the 2-AFC task to new spatial locations. Alternatively, the bats may have learnt the second discrimination task completely anew, and were faster only because of an acquired learning set. We suggest a dissociation between 2-AFC task acquisition and novel object discrimination learning to resolve the issue.
Cuttlefish responses to visual orientation of substrates, water flow and a model of motion camouflage
Authors: Shohet A. J. , Baddeley R. J. , Anderson J. C. , Kelman E. J. , Osorio D.
Published: November 2006

Low-level mechanisms in vertebrate vision are sensitive to line orientation. Here we investigate orientation sensitivity in the cuttlefish Sepia pharaonis, by allowing animals to settle on stripe patterns. When camouflaging themselves cuttlefish are known to be sensitive to image parameters such as contrast and spatial scale, but we find no effect of background orientation on the patterns displayed. It is nonetheless clear that the animals see orientation, because they prefer to rest with the body-axis perpendicular to the stripes. We consider three possible mechanisms to account for this behaviour. Firstly, that the body patterns are themselves oriented,and that the cuttlefish align themselves to aid static camouflage. This is unlikely, as the patterns displayed have no dominant orientation at any spatial scale. A second possibility is that motion camouflage favours alignment of the body orthogonal to background stripes, and we suggest how this alignment can minimise motion signals produced by occlusion. Thirdly we show that cuttlefish prefer to rest with their body-axis parallel to the water flow, and it is possible that they use visual patterns such as sand ripples to determine water flow.
Active vibration control of smart hull structures using piezoelectric actuators
Authors: Sohn J W , Kim H S , Choi S B
Published: November 2006

In this study, dynamic characteristics of an end-capped hull structure with surfacebonded piezoelectric actuators are studied and active vibration controller is designed to suppress the undesired vibration of the structure. Finite-element modelling is used to obtain practical governing equation of motion and boundary conditions of smart hull structure. A modal analysis is conducted to investigate the dynamic characteristics of the hull structure. Piezoelectric actuators are attached where the maximum control performance can be obtained. Active controller on the basis of a linear quadratic Gaussian (LQG) theory is designed to suppress the vibration of smart hull structure. It is observed that closed-loop damping can be improved with suitable weighting factors in the developed LQG controller and the structural vibration can be successfully suppressed.
Robust contact force estimation for robot manipulators in three-dimensional space
Authors: Jung J , Lee J , Huh K
Published: November 2006

Information on contact forces in robot manipulators is indispensable for fast and accurate force control. Instead of expensive force sensors, estimation algorithms for contact forces have been widely developed. However, it is not easy to obtain the accurate values due to uncertainties. In this article, a new robust estimator is proposed to estimate three-dimensional contact forces acting on a three-link robot manipulator. The estimator is based on the extended Kalman filter (EKF) structure combined with a Lyapunov-based adaptation law for estimating the contact force. In contrast to the conventional EKF the new estimator is designed such that it is robust to the deterministic uncertainties such as the modelling error and the sensing bias. The performance of the proposed estimator is evaluated through simulations of a robot manipulator and demonstrates robustness in estimating the contact force. The estimation results show that it can be potentially used to replace the expensive force sensors in robot applications.
Geometric design of a pinion with two circularly arrayed conical teeth for roller drives
Authors: Lai T-S
Published: November 2006

This article presents a mathematical model and geometric design algorithm for a new type of roller drive. The pinion has conical teeth in two circular arrays instead of one. This work is based on coordinate transformation and envelope theory, from which the equation of meshing of the cycloid drive is derived. The pinion profiles are the equidistant curves of the epicycloid profiles except the contour of the pinion conical tooth holes. Although there are twice as many pinion teeth as conventional rollers, their speed ratios are identical. This approach can design roller drives in which the pinion has two circular arrays of conical and cylindrical rollers. On the basis of these results, the corresponding solid modelling is constructed by CAD. Four examples are presented to demonstrate the feasibility of this approach. These examples can be a useful reference as a design case for other tooth profiles.
Study on high volumetric efficiency of the Roots rotor profile with variable trochoid ratio
Authors: Hwang Y-W , Hsieh C-F
Published: November 2006

Vacuum pumps play an important role in vacuum systems. The method proposed in this article, which uses the extended cycloid curve with a variable trochoid ratio, can be utilized to improve pump performance. The third-order and the fifth-order polynomials are used, and their boundary conditions are designed to generate a smooth trochoid ratio function. Hence, a regular addendum curve for the Roots rotor is generated. The tooth profile for the complete Roots rotor is derived from the addendum curve. Undercutting and carryover analyses are used to verify the feasibility of the designed method. Finally, a design flow on how to achieve high volumetric efficiency for a vacuum system is presented.
Dynamic analysis of a microelectromechanical systems resonant gyroscope excited using combination parametric resonance
Authors: Gallacher B J , Burdess J S
Published: November 2006

This paper investigates the application of parametric excitation to a resonant microelectromechanical systems (MEMS) gyroscope. The modal equations of motion of an electrostatically actuated ring are derived and shown to be coupled via the electrostatic stiffness. Such electrostatic coupling between in-plane modes of vibration permits parametric instabilities that may be exploited in a novel excitation scheme. A multiple time scale perturbation method is used to analyse the response of the ring gyroscope to the combination parametric excitations with the principal objective of separating the drive and response frequencies of the ring gyroscope. As pairs of flexural modes of the perfect ring are degenerate, the combination excitation between distinct modes demand the ring to be analysed as a four degree of freedom system. Slight mis-tuning between the otherwise degenerate modes is incorporated in the perturbation analysis. The results of the perturbation analysis are subsequently used to determine the stability boundaries for a typical ring gyroscope when excited using a sum combination resonance between the flexural modes of order 2 and 5. In this case, the ratio of the drive and response frequencies is approximately 10:1. Drive and sense configurations that enable effective parametric excitation of a desired mode are investigated. Simulation of the oscillator scheme is achieved using MATLAB Simulink and this validates the perturbation analysis. Agreement between the models within 10 per cent is demonstrated.
On the dead-centre position analysis of Stephenson six-link linkages
Authors: Tsai C-C , Wang L T
Published: November 2006

A new method for analysing the dead-centre positions of Stephenson type six-bar linkages is presented in this article. This method uses the input-output polynomial equation of the linkage and the corresponding Sturm functions to formulate the necessary condition of the dead-centre configurations as a polynomial equation in terms of the input parameter only. A simple analytical method for identifying the true dead-centre positions among the real solutions to the condition equation is also developed. The proposed method is conceptually straightforward and does not rely on any structure-related geometric conditions; therefore, it can be systematically applied to all types of Stephenson linkages and other multiple-loop, single degree-of-freedom linkages regardless of the selections of the input-output pair and the type of the joints.
Microactuation mechanism with piezoelectric element for magnetic recording head positioning for spin stand
Authors: He Z , Guo G , Feng L , Wong W E , Loh H T
Published: November 2006

A microactuation mechanism with piezoelectric element for positioning the magnetic head element is presented for high-density magnetic recording. The microactuation mechanism can be used in both magnetic disk drive and spin stand testing setup. A head-carrying cartridge used for carrying magnetic read/write head in the spin stand level is designed with the feature to mount piezoelectric microactuator(s) for microactuation. The static and dynamic behaviours of the head-carrying cartridge are evaluated by finite-element modelling. A modified design is proposed with much improved dynamic performance. The designs are prototyped and tested. Experimental dynamic testing and control implementation reveal that the proposed designs can be used for microactuation under high track density magnetic recording spin stand platform.
Application of slice spectral correlation density to gear defect detection
Authors: Bi G , Chen J , Zhou F C , He J
Published: November 2006

The most direct reflection of gear defect is the change in the amplitude and phase modulations of vibration. The slice spectral correlation density (SSCD) method presented in this paper can be used to extract modulation information from the gear vibration signal; amplitude and phase modulation information can be extracted either individually or in combination. This method can detect slight defects with comparatively evident phase modulation as well as serious defects with strong amplitude modulation. Experimental vibration signals presenting gear defects of different levels of severity verify to its character identification capability and indicate that the SSCD is an effective method, especially to detect defects at an early stage of development.
Taguchi-fuzzy-based approach for the sensitivity analysis of a four-bar function generator
Authors: Chen F-C , Huang H-H
Published: November 2006

This article aims to use the Taguchi method coupled with fuzzy logic on the tolerance sensitivity analysis of a four-bar function generator. Experiments designed by the Taguchi method were carried out for obtaining the mean and the maximum displacement variations of the function generator. By converting these two variations into a multiple performance index by means of fuzzy logic, the effect of each control factor on the mechanism quality was further analysed. The Taguchi method coupled with fuzzy logic was used to systematically analyse the effect of individual control factors on the displacement variations of a four-bar function generator from which the key dimensions were identified.
γ-Glutamyltransferase as a Predictor of Chronic Kidney Disease in Nonhypertensive and Nondiabetic Korean Men
Authors: Ryu Seungho , Chang Yoosoo , Kim Dong-Il , Kim Won Sool , Suh Byung-Seong
Published: November 2006

Background: Little research has been done to examine whether γ-glutamyltransferase (GGT) is prospectively associated with the development of chronic kidney disease (CKD). We performed a prospective study to examine the association between GGT and the risk for the development of CKD.

Methods: The study cohort included a total of 10 337 healthy males with normal baseline kidney functions and no proteinuria. Participants were workers in a semiconductor manufacturing company and its 13 affiliates. CKD was defined as either the presence of proteinuria or a glomerular filtration rate (GFR) of <60 mL · min−1 · (1.732)−1. Cox proportional hazards models were used to calculate the adjusted hazard ratios in separate models for CKD.

Results: During a follow-up period of 25 774.4 person-years, 366 men developed CKD. After adjustments were made for age, baseline GFR, triglyceride, and HDL-C, the risk for CKD increased with an increasing quartile of serum GGT (p for trend <0.001). The top one fourth of serum GGT vs the bottom one fourth of relative risks for CKD was 1.90 (95% confidence interval, 1.37–2.63). These associations were also apparent in participants who consumed ≤20 g/day of alcohol and those with normal weight, with values of alanine aminotransferase within reference intervals, or with C-reactive protein <3.0 mg/L, and participants without metabolic syndrome.

Conclusions: Our findings, which were obtained from a large work-site cohort and excluded individuals with diabetes and hypertension, indicated that serum GGT may be an early predictor for the development of CKD, independent of baseline confounding factors.
Coexistence of (Partial) Immune Defects and Risk of Recurrent Respiratory Infections
Authors: Bossuyt Xavier , Moens Leen , Van Hoeyveld Erna , Jeurissen Axel , Bogaert Guy , Sauer Kate , Proesmans Marijke , Raes Marc , De Boeck Kris
Published: November 2006

Background: Respiratory infections are major causes of morbidity and mortality, but determinants of susceptibility are poorly defined. We studied whether and to what extent immunologic and genetic factors are associated with increased susceptibility to respiratory infections.

Methods: We evaluated the prevalence of IgA, IgM, IgG, and IgG subclass deficiencies, impairment in the antibody response against pneumococcal polysaccharides, G2m(n) allotypes, FcγRIIa polymorphisms, partial C2 and partial C4 deficiency, promoter polymorphisms in MBL2, and lymphocyte subset deficiencies in a control population and in consecutive children with recurrent respiratory infections.

Results: IgA and/or IgG subclass deficiency was found in 27 of 55 patients (49%) and 6 of 43 controls (14%) (P = 0.0006). An impaired antibody response to polysaccharides was found in 7 patients (19%) and in 0 of 37 controls (P = 0.002). The Gm(n)marker was absent in 25 of 55 patients (45%) and 6 of 42 controls (14%) (P = 0.009). The MBL2 variants O/O, A/O, and A/A occurred in 9, 14, and 32 of the 55 patients, respectively, and in 1, 19, and 23 of the 43 controls, respectively (P = 0.05). There was no increase in the prevalence of partial C4 deficiency, C2 deficiency, lymphocyte subset deficiency, or FcγRIIa polymorphism in the patients compared to the controls. A combination of at least 2 immune defects was found in 31 of 55 patients (56%) and in 4 of 42 controls (11.6%) (P <0.0001).

Conclusion: Specific antipolysaccharide antibody deficiency, IgA and/or IgG subclass deficiency, Gm(n) allotype, and MBL2 genotype are susceptibility factors for recurrent respiratory infections, and coexistence of several immune defects is the strongest risk factor in this study.