bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recurrent Hypoxia in Rats during Development Increases Subsequent Respiratory Sensitivity to Fentanyl
Authors: Moss Immanuela Ravé , Brown Karen A. , Laferrière André 
Published: September 2006

Background
In children with a history of significant obstructive sleep apnea who undergo adenotonsillectomy, postsurgical administration of opiates has been alleged to be associated with an increased risk for respiratory complications, including respiratory depression. The authors hypothesize that this association is due to an effect of recurrent hypoxemia that accompanies more severe obstructive sleep apnea on altered responsiveness to subsequent exogenous opiates.

Methods
The current study was designed to test the effect of recurrent hypoxia in the developing rat on respiratory responses to subsequent administration of the mu-opioid agonist fentanyl. Rats were exposed to 12% oxygen balance nitrogen for 7 h daily for 17 days, from postnatal day 17 to 33, a period equivalent to human childhood. After 17 additional days in room air, rats were given a fentanyl dose and tested for their respiratory response to fentanyl using a whole body plethysmograph. Rats undergoing similar protocols without recurrent hypoxia served as controls.

Results
As compared with controls, rats preexposed to recurrent hypoxia displayed a more profound depression with fentanyl in minute ventilation, respiratory frequency, tidal volume, and tidal volume divided by inspiratory time that represents respiratory drive. These results indicated an increased respiratory sensitivity to fentanyl after recurrent hypoxia.

Conclusions
Previous recurrent hypoxia increases respiratory sensitivity to subsequent opiate agonists. If these findings are applicable to humans, opiate dosing in children must be adjusted depending on history of recurrent hypoxemia to avoid respiratory depression.
Prey choice and cannibalistic behaviour in the theropod
Coelophysis
Authors: Nesbitt Sterling J , Turner Alan H , Erickson Gregory M , Norell Mark A 
Published: September 2006

Abstract

Direct evidence of prey choice in carnivorous dinosaurs is rare in the fossil record. The most celebrated example pertains to purported stomach contents in the carnivorous dinosaur
Coelophysis bauri
, which besides revealing prey choice, also points to cannibalistic behaviour as being commonplace (
Colbert 1989
, 1995). Here, we test this hypothesis by conducting the first comprehensive anatomical and histological examination of the famed
Coelophysis
‘cannibals’. The results unequivocally show that the gut contents derive from early crocodylomorphs rather than juveniles of
Coelophysis
. These findings suggest that this taxon is not cannibalistic and bring into question the commonality of this behaviour among non-avian dinosaurs.
Hypothalamic–pituitary–adrenal axis activity and early onset of cannabis use
Authors: Huizink Anja C. , Ferdinand Robert F. , Ormel Johan , Verhulst Frank C. 
Published: September 2006

ABSTRACTAims  To identify early onset cannabis users by measuring basal hypothalamic–pituitary–adrenal (HPA) axis activity, which may be a risk factor for early onset substance use when showing low activity.Design  In a prospective cohort study, adolescents who initiated cannabis use at an early age (9–12 years), those who initiated at a later age (13–14 years) and those who did not use cannabis by the age of 14 were compared with respect to HPA axis activity.Setting and participants  Data were used from the first and second assessment wave of the TRacking Adolescents’ Individual Lives Survey (TRAILS), that included 1768 Dutch young adolescents aged 10–12 years who were followed‐up across a period of 2 years.Measurements  Cortisol was measured in saliva samples at awakening, 30 minutes later and at 8 p.m. at age 10–12. Self‐reported age at first cannabis use was used.Findings  The early onset group had lower cortisol levels 30 minutes after awakening than the late onset group (OR = 0.93, 95% CI: 0.86–0.99). Furthermore, compared to non‐users, the early and late onset cannabis users had higher levels of cortisol at 8 p.m. (OR = 1.25, 95% CI: 1.03–1.53 and OR = 1.21, 95% CI: 1.01–1.45, respectively).Conclusions  Some evidence was found for HPA axis hypo‐activity at awakening in adolescents with early onset of cannabis use compared to late onset users, which might indicate an increased risk for early onset users of seeking stimulation to restore arousal levels by using substances.
Transient over‐expression of barley BAX Inhibitor‐1 weakens oxidative defence and MLA12‐mediated resistance to Blumeria graminis f.sp. hordei
Authors: EICHMANN RUTH , DECHERT CORNELIA , KOGEL KARL‐HEINZ , HÜCKELHOVEN RALPH 
Published: September 2006

SUMMARYBAX Inhibitor‐1 (BI‐1) is a conserved cell death suppressor protein. In barley, BI‐1 (HvBI‐1) expression is induced upon powdery mildew infection and when over‐expressed in epidermal cells of barley, HvBI‐1 induces susceptibility to the biotrophic fungal pathogen Blumeria graminis. We co‐expressed mammalian pro‐apoptotic BAX together with HvBI‐1, and the mammalian BAX antagonist BCL‐XL in barley epidermal cells. BAX expression led to cessation of cytoplasmic streaming and collapse of the cytoplasm while co‐expression of HvBI‐1 and BCL‐XL partially or completely, respectively, rescued cells from BAX lethality. When B. graminis was attacking epidermal cells, a green fluorescent protein fusion of HvBI‐1 accumulated at the site of attempted penetration and was also present around haustoria. Over‐expression of HvBI‐1 in epidermal cells weakened a cell‐wall‐associated local hydrogen peroxide burst in a resistant mlo‐mutant genotype and supported haustoria accommodation in race‐specifically resistant MLA12‐barley. HvBI‐1 is a cell death regulator protein of barley with the potential to suppress host defence reactions.
Organic carbon and microbial biomass in two soil development chronosequences following glacial retreat
Authors: Conen F. , Yakutin M. V. , Zumbrunn T. , Leifeld J. 
Published: September 2006

SummaryRetreating glaciers successively expose mineral substrate which is colonised within a few years by soil biota, lichens and plants. Two such successions which cover the first five decades after exposure were studied in the Swiss Alps. Sites differed in parent material and precipitation. At each site, five strata of different age were dated by distance from the current glacier gate and records of annual retreat. The proportion of fine material (< 63 μm) differed by a factor of 2 between sites and a factor of 3 within sites. From the youngest to the oldest stratum, plant cover increased from < 5 to > 85% and organic carbon content (Corg) in the bulk material increased by 6 times at the wetter site and by 16 times at the drier site. Even so, partitioning of Corg between particle size fractions 2000 to 63 μm and < 63 μm was the same at both sites (6 : 4), and so was the proportion of microbial C (Cmic) in Corg (5%). Coefficients of variation across all 10 strata studied were only 22% for Corg partitioning and 21% for the proportion of Cmic in Corg. Soil carbon models frequently apply prescribed partitioning factors in simulating organic matter input into soil. Our findings lend support to such an approach.
Trophic transfer and trophic modification of fatty acids in high Arctic lakes
Authors: HESSEN DAG O. , LEU EVA 
Published: September 2006

Summary1. A comparative study of fatty acid (FA) profiles in particulate matter (seston) and the key grazer Daphnia was performed in six high Arctic ponds (79°N, Svalbard). The ponds were all small and shallow, but followed a strong gradient with respect to nutrient content and optical properties.2. A distinct locality‐specific pattern was detected by principal component analysis of FA profiles, where samples from each locality clustered both with regard to seston and Daphnia. Linear discriminant analysis using nine sestonic fatty acids as discriminant functions gave on average a correct prediction of the Daphnia lake membership in 47% of cases, with very high predictability in some lakes but poor predictability in others.3. No significant correlation was detected between FA and nutrient concentration or levels of dissolved organic carbon. The major determinant of FA profiles as judged from a redundancy analysis was the taxonomic composition of phytoplankton communities, notably the biomass of Chlorophyceae.4. The FA profiles of Daphnia were for some FAs strongly enriched relative to the seston, while diluted for others. Among the polyunsaturated fatty acids (PUFAs), a pronounced magnification of eicosapentaenoic acid (EPA, 20 : 5 n‐3), and to some extent 18 : 3 n‐3 and 20 : 4 n‐6 was found, while docosahexaenoic acid (DHA, 22 : 6 n‐3) contributed in general less to FAs in Daphnia than in seston and was hardly detectable in Daphnia from most localities.5. The overall content of PUFAs in Daphnia was consistently high, close to 40% of total FA in all investigated localities, despite major differences in seston PUFA content. Daphnia thus acts as a regulator with regard to overall PUFAs, reflecting its physiological constraints and relatively fixed demands for PUFAs in general. The distinct locality‐specific profiles in Daphnia strongly suggest a kind of FA‐fingerprint, but our data do not allow strict statements on the use of specific FAs as trophic markers.
Self‐organisation in streams: the relationship between movement behaviour and body condition in a headwater salamander
Authors: LOWE WINSOR H. , LIKENS GENE E. , COSENTINO BRADLEY J. 
Published: September 2006

Summary1. When movement behaviour is correlated with traits affecting fitness, it may affect population performance directly, independent of extrinsic habitat conditions.2. In a previous 3‐year, capture–recapture study, upstream movement by the salamander Gyrinophilus porphyriticus compensated for low reproduction in the upper 500 m of Merrill Brook, a first‐order stream in northern New Hampshire (U.S.A.). This immigrant subsidy resulted from excess reproduction in the downstream section (i.e. the lower 500 m of stream length) and from consistently upstream‐biased movement by salamanders. Reproduction in the two stream sections was positively correlated with mean body condition. Using 6 years of capture–recapture data, this study examines whether the movement behaviour of G. porphyriticus is related to body condition and thereby directly influences mean body condition and reproduction in the two sections of Merrill Brook.3. Upstream‐biased movement and greater mean body condition in the downstream section were consistent across 6 years of data collection. In Merrill Brook and four other streams, however, individuals with high body condition were more likely to move upstream and low‐condition individuals were more likely to move downstream. Movement direction was unrelated to the size, sex and initial location of individuals. Body condition was positively related to growth rate, further supporting its link to reproductive potential, and positively autocorrelated through time in individuals that moved.4. Results of this 6‐year study suggest that the movement behaviour of G. porphyriticus partially compensated for environmental factors differentiating mean body condition and reproduction along Merrill Brook and illustrate the potential for this form of self‐organisation to occur in linear habitats such as streams and rivers.
The effect of seed morphology on the potential dispersal of aquatic macrophytes by the common carp (Cyprinus carpio)
Authors: POLLUX B. J. A. , DE JONG M. , STEEGH A. , OUBORG N. J. , VAN GROENENDAEL J. M. , KLAASSEN M. 
Published: September 2006

Summary1. The potential for seed dispersal by fish (ichthyochory) will vary among aquatic plants because of differences in seed size and morphology.2. To examine how seed morphology influences the probability of dispersal by the common carp (Cyprinus carpio), we studied seed ingestion, retention time and subsequent egestion and germination of seeds of Sparganium emersum and Sagittaria sagittifolia, two aquatic plant species with similar sized but morphologically different seeds.3. We compared dispersal probabilities between the two plant species, in which the probability of dispersal is assumed to be a function of the probabilities of seed ingestion, egestion and germination, and the dispersal distance is assumed to be a function of seed egestion rate over time.4. We found that, although the soft seeds of S. sagittifolia had an approximately 1.5 times higher probability of being ingested by the carp than the hard seeds of S. emersum (83.15% ± 1.8% versus 56.16% ± 2.7%, respectively), the latter had an almost twofold higher probability of surviving the passage through the digestive tract (38.58% ± 2.7% versus 20.97% ± 1.5%, respectively). Patterns of seed egestion over time did not differ between the two plant species, despite the difference in seed morphology. Gut passage had a different effect on seed germination between plant species. Compared with non‐ingested controls, seeds of S. emersum showed a 12.6% increase in germination and a 2.1 day acceleration in germination rate, whereas seeds of S. sagittifolia displayed a 47.3% decrease and 5.1 day delay, respectively.5. Our results suggest that seed morphology affects the dispersal probability and postdispersal establishment, but not the dispersal distance, of aquatic plants that are dispersed by fish.
Crayfish in lakes and streams: individual and population responses to predation, productivity and substratum availability
Authors: NYSTRÖM PER , STENROTH PATRIK , HOLMQVIST NIKLAS , BERGLUND OLOF , LARSSON PER , GRANÉLI WILHELM 
Published: September 2006

Summary1. In a correlative study, we investigated the relative importance of fish predation, refuge availability and resource supply in determining the abundance and size distributions of the introduced and omnivorous signal crayfish (Pacifastacus leniusculus) in lakes and streams. Moreover, the biomass and food selection of predatory fish was estimated in each habitat type and stable isotopes of carbon and nitrogen were measured in perch (Perca fluviatilis), the dominant predator in the lakes, and in its potential food sources (crayfish, juvenile roach and isopods).2. In lakes, crayfish were the most frequent prey in large perch (46%), followed by other macroinvertebrates (26%, including the isopod Asellus aquaticus) and small fish (25%). Crayfish and fish dominated the gut contents of large perch with respect to biomass. Nitrogen signatures showed that perch were one trophic level above crayfish (approx. 3.4‰) and a two‐source mixing model using nitrogen isotope values indicated that crayfish (81%) contributed significantly more to perch isotope values than did juvenile roach (19%). A positive correlation was found between the abundance of crayfish and the biomass of large perch. Crayfish abundance in lakes was also positively correlated with the proportion of cobbles in the littoral zone. Lake productivity (chlorophyll a) was positively correlated with crayfish size, but not with crayfish abundance.3. In streams, brown trout (Salmo trutta) were the most abundant predatory fish. Gut contents of large trout in a forested stream showed that terrestrial insects were the most frequently found prey (60%), followed by small crayfish (27%) and isopods (27%). In contrast to lakes, the relative abundance of crayfish was negatively correlated with the total biomass of predatory fish and with total biomass of trout. However, abundance of crayfish at sites with a low biomass of predatory fish varied considerably and was related to substratum grain size, with fewer crayfish being caught when the substratum was sandy or dominated by large boulders. The mean size of crayfish was greater at stream sites with a high standing stock of periphyton, but neither predator biomass nor substratum grain size was correlated with crayfish size.4. Our results suggest that bottom‐up processes influence crayfish size in lakes and streams independent of predator biomass and substratum availability. However, bottom‐up processes do not influence crayfish abundance. Instead, substratum availability (lakes) and interactions between predation and substratum grain size (streams) need to be considered in order to predict crayfish abundance.
Mash1 promotes neuronal differentiation in the retina
Authors: Tomita Koichi , Nakanishi Shigetada , Guillemot Franqois , Kageyama Ryoichiro , Nishikawa Shin‐ichi 
Published: September 2006

AbstractBackground: Mash1, a mammalian homologue of Drosophila achaete‐scute proneural gene complex, plays an essential role in differentiation of subsets of peripheral neurones. Whereas Mash1 is expressed during retinal development, no apparent abnormalities were found during embryogenesis as well as at birth in Mash1‐null retina, suggesting that early differentiating cells such as ganglion, amacrine and cone cells develop normally. Because Mash1‐null mice die soon after birth, their postnatal development cannot be examined in vivo. Thus, it remains to be determined whether or not Mash1 functions in postnatal development of retina. Results: Here, Mash1 roles in postnatal development of retina was examined by using retinal explant that develops like in vivo retina. Without Mash1, differentiation of late appearing cells such as rod, horizontal, and bipolar cells was delayed and the final number of bipolar cells was significantly reduced. In contrast, vimentin‐positive cells (probably Müller glial cells) were increased in Mash1‐null retina. Conclusions: These results provide evidence that Mash1 promotes neuronal differentiation during retinal development and is essential for proper ratios of retinal cell types.
The Escherichia coli chromosome is organized with the left and right chromosome arms in separate cell halves
Authors: Nielsen Henrik J. , Ottesen Jesper R. , Youngren Brenda , Austin Stuart J. , Hansen Flemming G. 
Published: September 2006

SummaryWe have developed a system for the simultaneous labelling of two specific chromosomal sites using two different fluorescent ParB/parS systems. Using this, we demonstrate that the two chromosome arms are spatially arranged in newborn cells such that markers on the left arm of the chromosome lie in one half of the cell and markers on the right arm of the chromosome lie in the opposite half. This is achieved by reorganizing the chromosome arms of the two nucleoids in pre‐division cells relative to the cell quarters. The spatial reorganization of the chromosome arms ensures that the two replication forks remain in opposite halves of the cell during replication. The relative orientation of the two reorganized nucleoids in pre‐division cells is not random. Approximately 80% of dividing cells have their nucleoids oriented in a tandem configuration.
Cell‐mediated cytotoxicity is the main innate immune mechanism involved in the cellular defence of gilthead seabream (Teleostei: Sparidae) against Enteromyxum leei (Myxozoa)
Authors: CUESTA A. , SALINAS I. , RODRÍGUEZ A. , MUÑOZ P. , SITJÀ‐BOBADILLA A. , ÁLVAREZ‐PELLITERO P. , MESEGUER J. , ESTEBAN M. Á. 
Published: September 2006

SUMMARY The cellular innate immune response of gilthead seabream (Sparus aurata L.) against the myxozoan Enteromyxum leei was studied. Enteromyxosis was transmitted by maintaining uninfected fish (recipients) together with infected animals. A group of fish not exposed to the infection served as controls. After 10, 22, 38, 52 and 108 days, control and recipient fish were sampled and leucocyte subpopulations and cellular immune responses (leucocyte peroxidases, phagocytosis, respiratory burst and cytotoxicity) of the head‐kidney leucocytes were determined. The percentage of acidophilic granulocytes was significantly lower in non‐parasitized and parasitized recipient fish than in control fish after 22 days but no significant differences were seen between non‐parasitized and parasitized recipient animals. The leucocyte peroxidase content, phagocytosis and respiratory burst activity were seen to have decreased significantly at different sampling times in both non‐parasitized and parasitized recipient fish with respect to the controls, whereas cytotoxic activity was up to 2·3 times higher than in control fish. Within the recipient group, little difference was observed in the studied parameters between non‐parasitized and parasitized fish. These data demonstrate that cytotoxic activity may have an important role in the defence of gilthead seabream against the myxosporean E. leei. Immunological implications of E. leei infections are discussed.
Gonadectomy and progesterone treatment induce protection in murine cysticercosis
Authors: VARGAS‐VILLAVICENCIO J. A. , LARRALDE C. , MORALES‐MONTOR J. 
Published: September 2006

SUMMARY The effects of progesterone on castrated mice of both sexes infected with Taenia crassiceps cysticerci were studied. Gonadectomy and treatment with progesterone before infection decreased parasite loads by 100% compared with intact uninfected mice. mRNA levels of IFN‐γ and IL‐2 (typically associated to Th1‐like profiles) were markedly decreased in infected gonadectomized (Gx) mice, whereas progesterone treatment of infected Gx mice did not affected its expression. mRNA levels of IL‐4, and IL‐10 (typically associated with Th2‐like profiles) were reduced by gonadectomy, whereas restitution with progesterone did not affected this pattern in infected Gx progesterone‐treated mice. Infection markedly induced expression of progesterone receptor isoform A in splenocytes of Gx mice (5‐fold), whereas isoform B had no changes. Progesterone metabolism to dehydroepiandrosterone (DHEA) in Gx animals was increased 3‐fold only in infected progesterone‐treated uninfecteds of both sexes, but was not detectable in infected Gx progesterone‐treated mice. Conversely, DHEA levels increased 100‐fold in infected Gx progesterone‐treated mice. However, androgen receptor expression in splenocytes of male mice showed a reduction by gonadectomy, and by infection, whereas in females AR expression showed no changes in the different mouse groups. These results suggest that progesterone, through its metabolism to DHEA, negatively affects the establishment, growth, and reproduction of Taenia crassiceps, by a mechanism that does not implicate a classic genomic pathway involving a nuclear androgen receptor.
Expulsion of the gastrointestinal cestode, Hymenolepis diminuta by tolerant rats: evidence for mediation by a Th2 type immune enhanced goblet cell hyperplasia, increased mucin production and secretion
Authors: WEBB R. A. , HOQUE T. , DIMAS S. 
Published: September 2006

SUMMARY The processes underlying expulsion of Hymenolepis diminuta in rats are not known. Expression levels of mRNAs of several cytokines revealed a Th2 response that differed between worm infection levels. IL‐4 protein levels decreased while IL‐13 levels increased in a 50‐worm infection by 30 dpi; the converse was seen with a five‐worm infection. A negative correlation was found between IL‐4 or IL‐13 mRNA expression and worm biomass, between IL‐13 protein levels and worm number or worm biomass, and between IL‐4 protein levels and worm biomass in 50‐worm infections. A negative correlation between IL‐4 mRNA or protein expression and worm biomass was observed with five‐worm infections. A strong correlation between Muc2 mRNA expression and decreased worm number or biomass in a 50‐worm infection was observed. Muc2 protein, goblet cell numbers and mucin decreased in a 50‐worm infection by 20 days post‐infection. These changes were not seen with five‐worm infections where worms are not expelled. The data show that rats infected with 50 H. diminuta mount a Th2 response leading to high levels of IL‐13, increased goblet cell numbers and increased mucin2 production and release. The mucus traps the worms, which are progressively expelled from the small intestine.