bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ecological interactions of Pseudacteon parasitoids and Solenopsis ant hosts: environmental correlates of activity and effects on competitive hierarchies
Authors: Morrison Lloyd W. , Kawazoe Elizabeth A. , Guerra Rodney , Gilbert Lawrence E. 
Published: March 2003

Summary1. Solenopsis (Hymenoptera: Formicidae) fire ants are host to Pseudacteon (Diptera: Phoridae) parasitoids. The activity of S. geminata (F.) hosts and relative abundance of Pseudacteon phorids, along with five environmental variables, were measured at weekly intervals over an 8‐month period at two sites.2. Pseudacteon relative abundances often varied greatly from week to week, and were only weakly positively correlated with S. geminata activity.3. A quadratic function of soil temperature was the single best predictor of ant activity at both sites, explaining 32 and 73% of the variation in ant activity. A linear function of soil moisture was the single best predictor of phorid relative abundance at one site (r2 = 0.23) whereas no measured variables were significant predictors of phorid relative abundance at the other site.4. Interspecific interactions at 600 baits were monitored at a third site to document dominance hierarchies and determine whether the presence of Pseudacteon phorids mediated interspecific interactions in their host, S. geminata.5. Solenopsis geminata was near the top of dominance hierarchies, which did not diverge greatly from a linear pattern. Three species (S. geminata, S. invicta Buren, and Crematogaster laeviuscula Mayr) won the majority of their interspecific interactions and appear to be co‐dominants at this microhabitat‐rich site.6. Overall, the presence of phorids had no significant effect on the outcome of interspecific contests involving S. geminata and all other ant species grouped together. Phorids may have contributed to some of the S. geminata losses against other co‐dominant species.
Pollinator genetics and pollination: do honey bee colonies selected for pollen‐hoarding field better pollinators of cranberry Vaccinium macrocarpon?
Authors: Cane James H. , Schiffhauer Daniel 
Published: March 2003

Summary1. Genetic polymorphisms of flowering plants can influence pollinator foraging but it is not known whether heritable foraging polymorphisms of pollinators influence their pollination efficacies. Honey bees Apis mellifera L. visit cranberry flowers for nectar but rarely for pollen when alternative preferred flowers grow nearby.2. Cranberry flowers visited once by pollen‐foraging honey bees received four‐fold more stigmatic pollen than flowers visited by mere nectar‐foragers (excluding nectar thieves). Manual greenhouse pollinations with fixed numbers of pollen tetrads (0, 2, 4, 8, 16, 32) achieved maximal fruit set with just eight pollen tetrads. Pollen‐foraging honey bees yielded a calculated 63% more berries than equal numbers of non‐thieving nectar‐foragers, even though both classes of forager made stigmatic contact.3. Colonies headed by queens of a pollen‐hoarding genotype fielded significantly more pollen‐foraging trips than standard commercial genotypes, as did hives fitted with permanently engaged pollen traps or colonies containing more larvae. Pollen‐hoarding colonies together brought back twice as many cranberry pollen loads as control colonies, which was marginally significant despite marked daily variation in the proportion of collected pollen that was cranberry.4. Caloric supplementation of matched, paired colonies failed to enhance pollen foraging despite the meagre nectar yields of individual cranberry flowers.5. Heritable behavioural polymorphisms of the honey bee, such as pollen‐hoarding, can enhance fruit and seed set by a floral host (e.g. cranberry), but only if more preferred pollen hosts are absent or rare. Otherwise, honey bees' broad polylecty, flight range, and daily idiosyncrasies in floral fidelity will obscure specific pollen‐foraging differences at a given floral host, even among paired colonies in a seemingly uniform agricultural setting.
Bimodal life cycle of the burying beetle Nicrophorus quadripunctatus in relation to its summer reproductive diapause
Authors: Nisimura Tomoyosi , Kon Masahiro , Numata Hideharu 
Published: March 2003

Abstract 1. Under natural conditions in Kyoto, Japan, the reproductive activities of Nicrophorus quadripunctatus Kraatz (Coleoptera: Silphidae) decreased in summer and the species showed a bimodal life cycle.2. In the laboratory, most adult pairs raised at 20 °C under a LD 12:12 h regime reproduced when provided with a piece of chicken. In adults raised at 20 °C under a LD 16:8 h regime, however, both reproductive behaviour and ovarian development were reduced. It is concluded that these adults entered a reproductive summer diapause.3. High temperature (25 °C) also suppressed the reproductive behaviour even under a favourable LD 12:12 h regime. In the field, therefore, adults reduce their reproductive activity in summer because of diapause induced by long‐day photoperiods and direct inhibition of reproduction by high temperatures.4. When the temperature was changed from 20 °C to 25 °C immediately after hatching of larvae, they reached the wandering stage in 95% of adult pairs. When the temperature was changed from 20 °C to 25 °C immediately after oviposition, however, no larvae hatched in 85% of pairs. Egg mortality was significantly higher at 25 °C than at 20 and 22.5 °C; no eggs hatched at 27.5 °C. The physiological mechanisms for reducing reproduction probably prevent the beetles from inefficient oviposition in summer.
Priority effects of bamboo‐stump mosquito larvae: influences of water exchange and leaf litter input
Authors: Sunahara Toshihiko , Mogi Motoyoshi 
Published: March 2003

Abstract 1. A series of laboratory experiments was conducted to examine the influences of leaf litter input and flushing of medium on the priority effects of the two bamboo‐stump breeding mosquitoes, Aedes albopictus and Tripteroides bambusa, using 150‐ml microcosms. Larvae of either species were introduced to microcosms on day 0 (early cohort), at different densities, and day 14 (late cohort). The effects of the early cohort on survival, pupation, and biomass yield of the late cohort were compared among various combinations of the two species and among different treatments (water exchange, leaf addition, both of them, neither of them) on days 14 and 44.2. Survivorship and pupation success of the late A. albopictus cohort were affected negatively by the presence of either species of the early cohort to a greater extent than those of the late T. bambusa cohort.3. Water exchange reduced mortality of the late A. albopictus cohort over a short term in the presence of the early cohort of either species, indicating that a toxic substance was involved in the inhibitory priority effects. The addition of leaf litter enhanced survivorship and pupation of the late A. albopictus cohort, whether or not water was exchanged. The late T. bambusa cohort showed high survival rate with all treatments.4. The results indicate that leaf‐litter input moderates the inhibitory priority effects on A. albopictus larvae, not only by supplying food resources but also by alleviating the toxicity of accumulated dissolved substances.
A comparison of the host‐searching efficiency of two larval parasitoids of Plutella xylostella
Authors: Wang Xin‐Geng , Keller Michael A. 
Published: March 2003

Summary1. A host specialist parasitoid is thought to have greater efficiency in locating hosts or greater ability to overcome host defence than a generalist species. This leads to the prediction that a specialist should locate and parasitise more hosts than a generalist in a given arena. The work reported here tested these predictions by comparing the host‐searching behaviour of Diadegma semiclausum (a specialist) and Cotesia plutellae (an oligophagous species), two parasitoids of larval Plutella xylostella.2. Both parasitoids employed antennal search and ovipositor search when seeking hosts but D. semiclausum also seemed to use visual perception in the immediate vicinity of hosts.3. Larvae of P. xylostella avoided detection by parasitoids by moving away from damaged plant parts after short feeding bouts. When they encountered parasitoids, the larvae wriggled vigorously as they retreated and often hung from silk threads after dropping from a plant.4. These two parasitoids differed in their responses to host defences. Diadegma semiclausum displayed a wide‐area search around feeding damage and waited near the silk thread for a suspended host to climb up to the leaf, then attacked it again. Cotesia plutellae displayed an area‐restricted search and usually pursued the host down the silk thread onto the ground.5. Diadegma semiclausum showed a relatively fixed behavioural pattern leading to oviposition but C. plutellae exhibited a more plastic behavioural pattern.6. The time spent by the two parasitoids on different plants increased with increasing host density, but the time spent either on all plants or a single plant by D. semiclausum was longer than that of C. plutellae. Diadegma semiclausum visited individual plants more frequently than C. plutellae before it left the patch, and stung hosts at more than twice the rate of C. plutellae.7. The results indicated that the host‐location strategies employed by D. semiclausum were adapted better to the host's defensive behaviour, and thus it was more effective at detecting and parasitising the host than was C. plutellae.
Glucose intolerance in familial combined hyperlipidaemia
Authors: Vakkilainen  , Porkka  , Nuotio  , Pajukanta  , Suurinkeroinen  , Ylitalo  , Viikari  , Ehnholm  , Taskinen  ,   for the EUFAM study group
Published: March 2003

BackgroundFamilial combined hyperlipidaemia (FCHL) is a common hereditary disorder. Hypertriglyceridaemia is associated with glucose intolerance and insulin resistance.MethodsTo study glucose tolerance in FCHL patients with different lipid phenotypes [hypercholesterolaemia (IIA), mixed hyperlipidaemia (IIB), hypertriglyceridaemia (IV)], we investigated 253 family members and 92 spouses arising from 33 well‐defined Finnish FCHL pedigrees.ResultsIn oral glucose tolerance tests. the affected family members had higher values for glucose area under the curve than did non‐affected family members (673 ± 127 min mmol L−1, 754 ± 145 min mmol L−1, 846 ± 180 min mmol L−1 and 838 ± 183 min mmol L−1 for phenotypes normal, IIA, IIB and IV respectively; P < 0.001 after adjustment for body mass index, waist circumference and age). Impaired glucose tolerance and diabetes were more common among affected than non‐affected family members (prevalences of normal glucose tolerance 94.0%, 80.0%, 54.3% and 58.5% for phenotypes normal, IIA, IIB and IV).ConclusionAffected FCHL family members were more glucose intolerant than non‐affected family members. In men, this disturbance was not related to lipid phenotype nor was it explained by obesity.
Bezafibrate down‐regulates fibrinogen biosynthesis in human hepatoma HepG2 cells
Authors: Binsack  , Stegmeier  , Dörge  , Völkl  
Published: March 2003

BackgroundBezafibrate reportedly lowers serum lipids and plasma fibrinogen in humans and rats, but the mechanism of this process has still to be clarified. We have addressed this problem by investigating the effects of bezafibrate on fibrinogen in the human hepatoma HepG2 cell line.MethodsIn cells cultured with and without bezafibrate, intra‐ and extracellular fibrinogen was quantified using an enzyme‐linked immunosorbent assay (ELISA), and changes in the biosynthesis and secretion of bezafibrate were monitored by [35S]‐methionine labelling. In addition, expression of the corresponding mRNA was investigated by Northern blotting. As fibrinogen is an acute‐phase protein, HepG2 cells exposed to interleukin 6 were also analysed.ResultsBezafibrate decreased fibrinogen biosynthesis by about 25%, regardless of whether or not the cultures were also exposed to interleukin 6. mRNA was reduced in proportion to the concentration of interleukin 6 to which the cells were exposed, but intracellular transport and release of the protein were not affected.ConclusionApparently, bezafibrate interferes with the biosynthesis of fibrinogen at the pretranslational level but does not affect the export of the protein.
Antioxidants inhibit the in vitro production of inflammatory cytokines in Crohn's disease and ulcerative colitis
Authors: Reimund  , Allison  , Muller  , Dumont  , Kenney  , Baumann  , Duclos  , Poindron  
Published: March 2003

BackgroundModulation of cytokine secretion may be of interest in the treatment of Crohn's disease or ulcerative colitis.MethodsThe effect of three antioxidants — butylated hydroxyanisol, tetrahydropapaveroline and nordihydroguaiaretic acid — on the production of tumour necrosis factor (TNF), interleukin (IL) 1, IL‐6 and IL‐8 (measured by enzyme‐linked immunosorbent assay) by peripheral mononuclear cells and biopsies of inflamed colonic mucosa from inflammatory bowel disease patients were studied.ResultsWe observed a decrease in IL‐1 and IL‐6 production by peripheral mononuclear cells from inflammatory bowel disease patients (approximately 50% of control). The three drugs did not decrease IL‐6 and IL‐8 secretion by colonic biopsies, whereas they did inhibit IL‐1 and, to some degree, TNF production. The cytokine‐inhibitory effect of antioxidants seems to be more pronounced in ulcerative colitis than in Crohn's disease.ConclusionOur results suggest that the studied antioxidants, or related compounds, may be of interest in inflammatory bowel disease treatment.
Relationship between blood pressure, metabolic variables and blood flow in obese subjects with or without non‐insulin‐dependent diabetes mellitus
Authors: Jansson  , Larsson  , Lönnroth  
Published: March 2003

BackgroundTo assess the relationship between systemic blood pressure, metabolic variables and adipose tissue blood flow, we studied 55 subjects before and 36 subjects after an oral glucose load (100 g).MethodsThe subjects were divided into four different groups: (a) young lean control subjects [age 31 ± 1 years, mean ± SE, BMI (body mass index) 22.7 ± 0.4 kg m−2]; (b) young obese subjects (age 29 ± 2 years, BMI 37.8 ± 1.8 kg m−2); (c) middle‐aged obese subjects (age 50 ± 2 years, BMI 30.2 ± 0.9 kg m−2); and (d) middle‐aged obese non‐insulin‐dependent diabetic (NIDDM) subjects (age 54 ± 2 years, BMI 30.0 ± 0.7 kg m−2).ResultsGroups 2–4 demonstrated a low fasting adipose tissue blood flow (ATBF) and the increase in ATBF after oral glucose was impaired. A further impairment was present in NIDDM subjects. Systolic and diastolic blood pressure were also increased in groups 2–4 and further so in group 4. Fasting glucose, lactate and free fatty acid (FFA) levels correlated positively with the systolic blood pressure, whereas ATBF correlated negatively with the diastolic blood pressure. Furthermore, in the NIDDM subjects fasting lactate correlated closely with both the systolic (r = 0.649, P = 0.01) and diastolic (r = 0.626, P = 0.013) blood pressure.ConclusionThese data suggest a close relationship between insulin resistance and regulation of adipose tissue blood flow as well as blood pressure.
High‐energy phosphates metabolism and recovery in reperfused ischaemic hearts
Authors: Samaja  , Allibardi  , De Jonge  , Chierchia  
Published: March 2003

BackgroundThe aim of this study was to assess how coronary flow, oxygen supply and energy demand affect myocardial ATP, phosphocreatine and their metabolites during oxygen shortage and recovery.MethodsIsolated rat hearts were exposed for 20 min to either low‐flow ischaemia or hypoxaemia at the same oxygen supply, followed by return to baseline conditions (20 min). Seventy‐three hearts were divided into four groups: ischaemic or hypoxaemic, spontaneously beating or paced to increase energy demand.ResultsDuring O2 shortage, myocardial performance was less in ischaemic, spontaneously beating hearts (SpIs), than in the other groups (14 ± 1% of baseline vs. 25–48%). Consequently, the tissue levels of ATP, total adenylates and phosphocreatine were maintained in SpIs, in contrast to marked decreases in the other groups. Upon reflow, the recovery of performance and of myocardial ATP was 94 ± 5% in SpIs (P = NS vs. baseline) compared with 64–85% (P < 0.05 vs. baseline) in the other groups. The degree of recovery was positively related to the ischaemic contents of ATP (P = 0.03) and adenylates (P = 0.001), but not to that of phosphocreatine (P = NS).ConclusionThe maintenance of the ATP pool under low oxygen supply conditions is essential for good recovery. The most important factors that determine the ATP pool size are the energy demand, which increases the formation of diffusible ATP catabolites, and the coronary flow, which removes these catabolites, rather than the oxygen supply per se.
Peripheral markers of oxidative stress in probable Alzheimer patients
Authors: Repetto  , Reides  , Evelson  , Kohan  , De Lustig  , Llesuy  
Published: March 2003

BackgroundThe current research on Alzheimer's disease is mainly focused in the post‐mortem characterization of pathological and biochemical alterations in the brain. The finding of peripheral markers that could be associated with the changes observed in the Alzheimer's brain would be of interest in this field. The aim of the present study was to evaluate the state of different peripheral markers of oxidative stress in probable Alzheimer patients and compare them with a group of healthy individuals.DesignThe determinations made include the plasma total antioxidant capacity (TRAP) and tert‐butyl hydroperoxide‐initiated chemiluminescence and catalase activity in erythrocytes from 18 patients with probable Alzheimer's disease and 18 matched control subjects with normal cognitive function.ResultsTRAP was decreased in Alzheimer patients by 24% (control group 308 μmol L−1 Trolox, SEM 34, n = 18). tert‐Butyl hydroperoxide‐initiated chemiluminescence and catalase activity showed an increase in erythrocytes from Alzheimer patients by 52% (control group 116 700 cps mg−1 haemoglobin, SEM 6690) and 75% (control group 2.55 pmol mg−1 protein, SEM 0.39, n = 18) respectively.ConclusionOxidative stress in the blood of probable Alzheimer patients could be a reflection of the brain condition and suggests that oxygen free radicals could be partially responsible of the damage observed in this disease.
Serum hyaluronan as a predictor of hepatic regeneration after hepatectomy in humans
Authors: Ogata  , Okuda  , Ueno  , Saito  , Aoyagi  
Published: March 2003

BackgroundThe capacity for hepatic regeneration after hepatectomy is important for allowing surgeons to determine the appropriate extent of resection. However, conventional preoperative liver function tests are unsatisfactory for estimating the post‐operative regenerative capacity of the remnant liver. The aim of this study was to evaluate the relationship between preoperative serum hyaluronan and hepatic regeneration.MethodsPreoperative serum hyaluronan levels and the hepatic regeneration rate were estimated in 49 patients using computerized tomographic volumetry. The hepatic fibrotic rate was calculated with non‐tumorous tissues stained with Azan–Mallory. Immunolocalization of factor VIII‐related antigen (FVIIIAg) was examined as a marker for hepatic sinusoidal capillarization.ResultsThe serum hyaluronan level was significantly correlated with the hepatic regeneration rate (P < 0.001). Patients with serum hyaluronan levels below 200 ng mL−1 exhibited a significant correlation between the hepatic regeneration rate and the hepatic fibrotic rate. However, patients with serum hyaluronan levels above 200 ng mL−1 did not demonstrate a distinct correlation. The hepatic regeneration rate of patients with FVIIIAg in the liver and serum hyaluronan levels above 200 ng mL−1 were very low compared with those without FVIIIAg (P < 0.001). Multiple regression analysis revealed that serum hyaluronan was a significant predictor of post‐operative hepatic regeneration among several clinical variables (r = 0.857, R2 = 0.735).ConclusionIt has been suggested that hepatic regeneration is closely related to both hepatic fibrosis and hepatic sinusoidal capillarization. The serum hyaluronan level is regarded as a useful predictor for hepatic regeneration after hepatectomy.
mRNA expression patterns of insulin‐like growth factor system components in human neuroendocrine tumours
Authors: Wulbrand  , Remmert  , Zöfel  , Wied  , Arnold  , Fehmann  
Published: March 2003

BackgroundInsulin‐like growth factors (IGF) and their corresponding receptors and binding proteins are important in carcinogenesis for several tumours, but their expression pattern in the functionally and biologically heterogeneous human neuroendocrine tumours of the gastroenteropancreatic tract is largely unknown.Materials and methodsThis study searched for the mRNA expression patterns of components of the IGF system: IGF‐1 and IGF‐2, IGF receptors 1 and 2 (IGF‐1R, IGF‐2R), IGF‐binding proteins 1–6 (IGFBP1–6)) in the most frequent human gastroenteropancreatic neuroendocrine tumours (gastrinomas, insulinomas, tumours associated with carcinoid syndrome and functionally inactive tumours) employing reverse transcriptase‐polymerase chain reaction (RT‐PCR).ResultsIn the 37 tumour samples analysed (nine gastrinomas, 10 insulinomas, nine tumours associated with carcinoid syndrome and nine functionally inactive tumours) IGFBP‐2 was found in all tumour samples while the IGFBP‐1 was expressed only at low frequency (10–22%) among the four tumour types. The IGF‐2R was predominantly expressed in gastrinomas. Among the four tumour types the expression of IGF‐1R, IGF‐2R and IGFBP‐6 varied significantly. In addition, 12 pairs of significantly coexpressed IGF system components were detected (IGF‐1 ↔ IGF‐1R, IGF‐1 ↔ IGF‐2R, IGF‐1 ↔ IGFBP‐3, IGF‐1 ↔ IGFBP‐6, IGFBP‐3 ↔ IGF‐1R, IGFBP‐6 ↔ IGF‐1R, IGFBP‐1 ↔ IGF‐2R, IGFBP‐3 ↔ IGF‐2R, IGFBP‐5 ↔ IGF‐2R, IGFBP‐3 ↔ IGFBP‐5, IGFBP‐3 ↔ IGFBP‐6, IGFBP‐5 ↔ IGFBP‐6).ConclusionsThe described differences of the expression patterns of the IGF system components in neuroendocrine tumour subtypes suggest tumour type‐dependent different pathways in tumour growth control by IGF system components.
Investigation of bone changes in microgravity during long and short duration space flight: comparison of techniques
Authors: McCarthy I. , Goodship A. , Herzog R. , Oganov V. , Stussi E. , Vahlensieck M. 
Published: March 2003

Loss of bone mass is a continuing problem in long‐term space flight. Although counter‐measure programmes have been developed, effective assessment of these programmes is hampered by a lack of monitoring techniques that can be used in‐flight.Three techniques were used to evaluate changes in bone during two missions of 180 and 20 days to the MIR space station, involving three subjects. Dual energy X‐ray absorptiometry (DXA) was used before and after flight to measure whole body and regional bone mineral density (BMD). Ultrasonic measurements of velocity (SOS) and broadband attenuation (BUA) of the calcaneus were measured during the 180 day mission and before and after the 20 day mission. Phase velocity of flexural waves in the tibia was also measured on the same days as the ultrasonic measurements of the calcaneus.DXA measurements demonstrated significant variation between different sites in the body for changes in BMD, with the greatest changes occurring in the lumbar spine and proximal femur. There was a trend for increasing phase velocity in the tibia during the 180 mission, but this was not significant. BUA and SOS measurements of the calcaneus showed consistent but divergent patterns of changes during the mission.Although in‐flight measurements of bone using ultrasound or phase velocity may provide information on the kinetics of bone loss in space flight, the heterogeneity of response in the skeleton means that it is difficult to predict overall bone loss from measurements at one particular site.