bluuebunny/crossref_metadata_2025_split huggingface dataset:
Geographical variation in host–ant specificity of the parasitic butterfly Maculinea alcon in Denmark
Authors: Als Thomas Damm , Nash David R. , Boomsma Jacobus J. 
Published: March 2003

Abstract  1. Maculinea alcon uses three different species of Myrmica host ants along a north–south gradient in Europe. Based on this geographical variation in host ant use, Elmes et al. (1994) suggested that M. alcon might consist of three or more cryptic species or host races, each using a single and different host‐ant species.2. Population‐specific differences in allozyme genotypes of M. alcon in Denmark (Gadeberg & Boomsma, 1997) have suggested that genetically differentiated forms may occur in a gradient across Denmark, possibly in relation to the use of different host ants.3. It was found that two host‐ant species are indeed used as hosts in Denmark, but not in a clear‐cut north–south gradient. Furthermore, specificity was not complete for many M. alcon populations. Of five populations investigated in detail, one used primarily M. rubra as a host, another exclusively used M. ruginodis, while the other three populations used both ant species. No population in Denmark used M. scabrinodis as a host, although this species was present in the habitat and is known to be a host in central and southern Europe.4. In terms of number of parasites per nest and number of nests parasitised, M. rubra seems to be a more suitable host in populations where two host species are used simultaneously. Host‐ant species has an influence on caterpillar size but this varies geographically. Analyses of pupae did not, however, show size differences between M. alcon raised in M. rubra and M. ruginodis nests.5. The geographical mosaic of host specificity and demography of M. alcon in Denmark probably reflects the co‐evolution of M. alcon with two alternative host species. This system therefore provides an interesting opportunity for studying details of the evolution of parasite specificity and the dynamics of host‐race formation.
Thermal ecology of western tent caterpillars Malacosoma californicum pluviale and infection by nucleopolyhedrovirus
Authors: Frid Leonardo , Myers Judith H. 
Published: March 2003

Abstract 1. Western tent caterpillars hatch in the early spring when temperatures are cool and variable. They compensate for sub‐optimal air temperatures by basking in the sun.2. Tent caterpillars have cyclic population dynamics and infection by nucleopolyhedrovirus (NPV) often occurs in populations at high density.3. To determine whether climatic variation might influence viral infection, the environmental determinants of larval body temperature and the effects of temperature on growth and development rates and larval susceptibility to NPV were examined.4. In the field, larval body temperature was determined by ambient temperature, irradiance, and larval stage. The relationship between larval body temperature and ambient temperature was curvilinear, a property consistent with, but not necessarily limited to, behaviourally thermoregulating organisms.5. Larvae were reared at seven temperatures between 18 and 36 °C. Larval growth and development increased linearly with temperature to 30 °C, increased at a lower rate to 33 °C, then decreased to 36 °C. Pupal weights were highest for larvae reared between 27 and 30 °C.6. The pathogenicity (LD50) of NPV was not influenced by temperature, but the time to death of infected larvae declined asymptotically as temperature increased.7. Taking into account larval growth, the theoretical yield of the virus increased significantly between 18 and 21 °C then decreased slightly as temperatures increased to 36 °C.8. Control and infected larvae showed no difference in temperature preference on a thermal gradient. The modes of temperature preference were similar to those for optimal growth and asymptotic body temperatures measured in the field on sunny days.9. Warmer temperatures attained by basking may increase the number of infection cycles in sunny springs but do not protect larvae from viral infection.
Plant volatiles in the sexual communication of Melolontha hippocastani: response towards time‐dependent bouquets and novel function of (Z)‐3‐hexen‐1‐ol as a sexual kairomone
Authors: Ruther Joachim , Reinecke Andreas , Hilker Monika 
Published: March 2003

Summary1. Swarming males of Melolontha hippocastani are known to locate females that stay feeding within the host trees by orienting towards damage‐induced plant volatiles (green leaf volatiles) and a sex pheromone. Thus, volatiles emitted by freshly damaged leaves might indicate to a male the presence of currently feeding females.2. The hypothesis was studied that volatiles from freshly damaged leaves are more attractive to males than volatiles from old damaged leaves. The odour bouquets of damaged leaves from three plant species that have been shown to attract male M. hippocastani in the field were analysed 10 min (fresh damage) and 1.5 h (old damage) after damaging, using coupled gas chromatography–mass spectrometry. The results showed clear differences between the bouquets: the bouquet of freshly damaged leaves of all species consisted of typical leaf aldehydes, i.e. hexanal, (Z)‐3‐hexenal, (Z)‐2‐hexenal, (E)‐2‐hexenal, the leaf alcohol (Z)‐3‐hexen‐1‐ol, and the corresponding acetate. One and a half hours after damage, aldehydes had almost vanished and (Z)‐3‐hexen‐1‐ol and (Z)‐3‐hexenyl acetate predominated; however males of M. hippocastani were equally attracted to traps baited with volatiles from old and freshly damaged leaves in field experiments. When traps were baited with synthetic volatile mixtures mimicking the bouquets of old and freshly damaged leaves, M. hippocastani males even preferred the old damage mixture.3. Experiments addressing the role of individual green leaf volatiles revealed that only (Z)‐3‐hexen‐1‐ol was highly attractive while the other compounds tested individually were behaviourally inactive, however all tested compounds elicited comparable electrophysiological responses on male M. hippocastani antennae.4. In analogy to the term aggregation kairomone used for feeding‐induced plant volatiles that attract both sexes of an insect, the term sexual kairomone is suggested to describe the novel function of (Z)‐3‐hexen‐1‐ol in the sexual communication of M. hippocastani.
Seasonal changes in leaf nutritional quality influence grass miner performance
Authors: Scheirs J. , Bruyn L. De , Verhagen R. 
Published: March 2003

Summary1. The plant phenological age hypothesis predicts that phytophagous insects should prefer and perform better on phenologically young plants than on old plants because plant nutritional quality decreases with plant phenological age. This hypothesis was tested under field and laboratory conditions with the grass miner Chromatomyia milii on the free‐growth species Holcus lanatus.2. The field experiment was conducted at four sample sites in Belgium where nutritional quality of H. lanatus leaves and performance of C. milii were monitored throughout the growth season. Foliar nutritional quality was highest early in the season due to high levels of proteins and soluble carbohydrates and low levels of lignin. Offspring performance (pupal size) decreased with plant phenological age, due at least partially to the decreasing foliar nutritional quality.3. In the laboratory experiment, preference and performance of C. milii were determined on three different age classes of H. lanatus. Multiple‐choice experiments demonstrated that oviposition preference did not differ among age classes. Offspring survival decreased with plant phenological age, while pupal size did not differ among age classes. The relationship between foliar nutritional quality and plant phenological age was equivocal and did not correspond to the predictions of the plant phenological age hypothesis.4. The results of the field experiment were consistent with the idea that the phenological age hypothesis holds in free‐growth species. The laboratory experiment gave only little support to the plant phenological age hypothesis. Possible causes for the differences between field and laboratory experiments are discussed.
Do hypotheses from short‐term studies hold in the long‐term? An empirical test
Authors: Hellmann Jessica J. , Weiss Stuart B. , Mclaughlin John F. , Boggs Carol L. , Ehrlich Paul R. , Launer Alan E. , Murphy Dennis D. 
Published: March 2003

Abstract. 1. A sequence of population estimates for two now‐extinct populations of Euphydryas editha bayensis is presented. After removing biased sampling days, estimates of demographic parameters from the long‐term data were used to test five hypotheses built from studies of shorter duration. Such tests of short‐term conclusions are rare.2. The long‐term demographic parameters include sex ratio, mortality, dispersal, mean flight date, and duration of flight season. The two populations differed with respect to sex ratio and mean flight date, and sexes differed with respect to mortality and dispersal.3. Three of the five hypotheses were supported directly or indirectly by patterns in the parameters. These hypotheses predict that dynamics are asynchronous over the long term, that larval mortality, not adult abundance and mortality, is the primary determinant of changes in population size, and that topography mediates larval mortality.4. Two hypotheses were not supported or supported only in part. Flight phenology differed between the study populations as predicted, but flight order was opposite that expected from the topographic composition of each habitat. Variability in sex ratio and the occurrence of female‐biased ratios in the habitat of one of the populations also suggest that previous observations of sex ratio are not generalisable.5. Populations were extremely volatile over the study period. Removal of biased sampling days did not change basic trends or fluctuations in the data. This volatility suggests that E. editha populations residing in similar habitats may risk immediate extinction.
Immunological relatedness of the protective mechanisms against tuberculosis and cancer
Authors: Cocito  , Maes  
Published: March 2003

BackgroundBacille Calmette–Guérin (BCG), an attenuated strain of tuberculous bacillus, is the source of vaccines providing unclear and variable protection against tuberculosis (TB) and cancer. Thermostable macromolecular antigens (TMAs) are major mycobacterial complexes immunodominant in disease. A60 (TMA complex of BCG) protects mice against TB development, via T lymphocyte (TL)‐mediated macrophage (MΦ) activation, halting intracellular mycobacterial replication. In most A60‐primed mice, cytolytic TLs and MΦ infiltrate cancer tissue, resulting in 80–100% rejection. Adoptive TL transfer is indispensable for MΦ‐dependent tumour cell inactivation via oxygen and nitrogen radicals. Neoplasm development induces immune anergy with depletion of A60‐specific TL and activated MΦ. A60 protects mice against TB and cancer by inducing the synthesis of three lymphokines: interleukin 2 (IL‐2), interferon gamma (IFN‐γ) and tumour necrosis factor alpha (TNF‐α). Tumour cells prevent A60‐dependent synthesis of these lymphokines in vivo and in vitro.ConclusionThese data provide some clues to immune surveillance and tumour escape mechanisms, as well as to the antituberculous and antineoplastic BCG action.
Regulation of gp330/megalin expression by vitamins A and D
Authors: Liu  , Yu  , Carling  , Juhlin  , Rastad  , Ridefelt  , Åkerström  , Hellman  
Published: March 2003

BackgroundA membrane‐bound 550‐kD Ca2+‐binding glycoprotein belonging to the low‐density lipoprotein (LDL) receptor superfamily has recently been identified as a putative calcium‐sensing molecule. This molecule, known as gp330/megalin, is among several tissues present in the proximal tubule, parathyroid and placental cytotrophoblasts, in which a Ca2+‐sensing function has been demonstrated.MethodsRegulation of mRNA and protein expression of gp330/megalin were studied in a recently established cell line derived from rat kidney proximal tubule cells (IRPTCs), in human JEG‐3 cells and in the mouse embryonal carcinoma cell line F9.ResultsIn IRPTCs, quantification of mRNA and protein expression demonstrated two‐ to five‐fold increases after addition of 10−6 mol L−1 all‐trans‐retinoic acid, 9‐cis‐retinoic acid or 1,25‐dihydroxyvitamin D3, alone or in combination. Similarly, an increase in gp330/megalin mRNA expression was seen in JEG‐3 cells cultured with vitamin D and retinoids, as well as when F9 cells were differentiated by incubation with retinoic acid and cAMP. The IRPTCs were immortalized by viral infection with the SV40 genome preceded by a temperature‐sensitive promoter. Thus, by culture of the cells at 41°C, SV40 genome transcription is inhibited and the IRPTC phenotype is reversed towards non‐infected proximal tubule cells. At 41°C, gp330/megalin mRNA expression was significantly increased compared with cells incubated at 34°C.ConclusionThe results indicate a correlation between exposure to retinoic acid or vitamin D or induction of cell differentiation (by retinoic acid/cAMP in F9 cells or inhibition of SV40 transcription in IRPTCs) and an increase in gp330/megalin protein and mRNA expression.
Effects of anti‐C5a monoclonal antibodies on oxygen use in a porcine model of severe sgifis
Authors: Mohr  , Höpken  , Oppermann  , Mathes  , Goldmann  , Siever  , Götze  , Burchardi  
Published: March 2003

MethodsWe analysed the effects of complement depletion and of C5a inhibition on haemodynamic parameters, oxygen delivery (DO2), oxygen consumption (VO2), oxygen extraction ratio (OER) and blood lactate levels after live bacteria infusion in pigs.ResultsIn the first series of experiments, animals were decomplemented by cobra venom factor (CVF, 125 μg kg−1) and challenged with 1.3 × 109Escherichia coli kg−1. In a second series, animals were treated with neutralizing anti‐C5a monoclonal antibodies (mAb) T13/9 before infusion of an increased E. coli dosage (1 × 1010 E. coli kg−1). Administration of Gram‐negative bacteria resulted in hypotension, tachycardia, pulmonary hypertension and decreased cardiac output typical for severe sgifis. These alterations were more pronounced in animals challenged with a higher bacteria concentration (1 × 1010 E. coli kg−1, n = 5) than with a lower dosage (1.3 × 109E. coli kg−1, n = 4). Complement depletion by CVF injection 24 h before E. coli infusion (n = 4), or anti‐C5a mAb T13/9 administration (n = 4) had no effect on the changes in haemodynamic parameters and in DO2 associated with E. coli challenge. Application of either 1.3 × 109 or 1 × 1010 E. coli kg−1resulted in a marked decrease in VO2 and an increase in blood lactate levels, whereas the OER did not change throughout the experiment. In contrast, pretreatment with CVF 24 h before low‐dose E. coli (1.3 × 109 kg−1) administration resulted in a significant increase in VO2 (P < 0.05) and in OER (P < 0.05) compared with untreated septic animals (n = 4). No hyperlactaemia occurred in complement‐depleted septic animals compared with complement‐sufficient animals (P < 0.05). Animals challenged with a high E. coli dose (1 × 101 kg−1) and treated with anti‐C5a mAbs showed a pronounced increase in VO2 and OER (P < 0.05) accompanied by an attenuated increase in lactate levels (P < 0.05) compared with untreated septic animals.ConclusionThe results demonstrate an improved oxygen use after complement depletion in this model of severe Gram‐negative sgifis. Furthermore, a similar effect was seen after specifically neutralizing C5a by mAbs, indicating a role of C5a in the underlying mechanism.
Oral guar gum treatment of intrahepatic cholestasis and pruritus in pregnant women: effects on serum cholestanol and other non‐cholesterol sterols
Authors: Gylling  , Riikonen  , Nikkilä  , Savonius  , Miettinen  
Published: March 2003

BackgroundOur aim was to investigate whether intestinal binding of bile acids by guar gum, a dietary fibre, relieves cholestasis and pruritus in intrahepatic cholestasis of pregnancy.MethodsForty‐eight pregnant women with cholestasis and pruritus were randomized double‐blind to guar gum and placebo until the time of delivery, and 20 healthy pregnant women were used as control subjects. The pruritus score and serum bile acids, lipids and non‐cholesterol sterols were measured at baseline, at least 2 weeks after treatment, just before delivery and up to 4 weeks after delivery.ResultsThe increase in serum bile acids and worsening of pruritus were prevented by guar gum in relation to placebo (P < 0.05). Serum cholesterol was unchanged, but increased cholesterol precursor sterol values suggested that cholesterol synthesis was increased by guar gum. Serum cholestanol proportion, an indicator of cholestasis, was related to pruritus but was unaffected by guar gum.ConclusionWe conclude that in intrahepatic cholestasis of pregnancy and pruritus, guar gum treatment is beneficial in relieving pruritus, even although indicators of cholestasis are only partially reduced.
Effects of parathyroid hormone and serum calcium on the phenotype and function of mononuclear cells in patients with primary hyperparathyroidism
Authors: Kotzmann  , Köller  , Abela  , Clodi  , Riedl  , Graninger  , Niederle  , Luger  
Published: March 2003

BackgroundSeveral studies have demonstrated specific influence of parathyroid hormone (PTH) on immune parameters, especially on T‐ and B‐cell function, migration of polymorphonuclear leucocytes (PMNLs) and antibody synthesis, in patients with secondary hyperparathyroidism and chronic renal failure and recently also in patients with primary hyperparathyroidism (pHPT).MethodsWe therefore examined 12 patients with pHPT before and 6 months after parathyroidectomy (PTX) and nine sex‐ and age‐matched control subjects to determine the impact of PTH and serum calcium concentrations on several immune parameters, including (a) serum concentrations of immunoglobulins, (b) immunophenotype of peripheral blood lymphocytes, (c) phytohaemagglutinin (PHA)‐induced lymphocyte proliferation and (d) monocytic surface marker expression.ResultsSerum concentrations of immunoglobulins (IgG, IgA, IgM) were unaffected by elevated serum PTH and calcium levels. T lymphocytes (CD3), B lymphocytes (CD19), NK cells (CD16/56) and monocytes (CD16) revealed a normal distribution and were not different before and after PTX in patients with pHPT when compared with the control group. CD4+ T‐helper lymphocytes were significantly elevated pre‐ and post‐operatively in patients with pHPT. The lymphocyte proliferation response to PHA in the highest concentration (12.5 μg L−1) tested was significantly suppressed in patients with pHPT preoperatively when compared with the patients post‐operatively and the control group. In addition, both CD4+ and CD8+ lymphocytes showed a lower expression of activation markers, interleukin 2 (IL‐2) receptor (CD25) and transferrin receptor (CD71), which could be partially restored 6 months after PTX, but did not reach normal values.ConclusionIn summary, in contrast to the findings in patients with secondary HPT, pHPT appears to be associated with less alterations of immune functions. Chronically elevated serum PTH and calcium concentrations in patients with pHPT induce a higher percentage of CD4+ helper T lymphocytes and a suppressed lymphocyte response to PHA as well as a reduced expression of activation markers on peripheral blood lymphocytes.
Effect of metformin on food intake in obese subjects
Authors: Paolisso  , Amato  , Eccellente  , Gambardella  , Tagliamonte  , Varricchio  , Carella  , Giugliano  , D'onofrio  
Published: March 2003

BackgroundIt has been hypothesized that metformin inhibits food intake, but in humans such effect needs to be demonstrated. Our study aims at investigating the effect of metformin administration on food intake in obese, non‐diabetic, normotensive patients.MethodsThirty patients underwent a double‐blind, randomized study. Placebo (P; n = 15) and metformin (M; n = 15) were both given for 15 days, and food intake (FI) was recorded at baseline and in the last 4 days of each treatment period.ResultsM administration allowed a stronger decline in body weight (BW) (−2.8 ± 1.6 vs. −0.3 ± 0.4 kg P < 0.01), body fat (BF) (−1.4 ± 1.2 vs. −0.3 ± 1.1 kg P < 0.01), plasma leptin concentration (−5.2 ± 8.9 vs. −1.8 ± 10.4 ng mL−1P < 0.05) and FI (−642 ± 491 vs. −70 ± 1165 kJ per 24 h P < 0.01) than P. In M‐treated subjects, changes in FI significantly correlated with those in BW (r = 0.63, P < 0.007) and BF (r = 0.74, P < 0.001). Independently of sex and change in BF, the changes in FI and in fasting plasma leptin concentration (r = 0.58, P < 0.01) were still correlated.ConclusionOur study suggests that metformin administration is useful to inhibit FI and to lower BW and BF in obese non‐diabetic patients.
Lipoprotein (a) induces angiogenesis on the chick embryo chorioallantoic membrane
Authors: Ribatti  , Vacca  , Giacchetta  , Cesaretti  , Anichini  , Roncali  , Damacco  
Published: March 2003

BackgroundBoth lipoprotein (a) [Lp(a)] and angiogenesis have been shown to be associated with initiation and progression of atherosclerotic plaque. Lp(a) and two neutralizing anti‐Lp(a) antibodies were investigated for their capacity to affect the vasoproliferative processes of the chick embryo chorioallantoic membrane (CAM), a useful model for such an investigation.MethodsGelatin sponges loaded with Lp(a) alone or together with anti‐Lp(a) antibodies, or with vehicle alone, phosphate‐buffered saline (PBS), were implanted in vivo onto the CAM at incubation day 8. Four days later, sponges and the adjacent CAM tissues were assessed for the extent of angiogenesis in terms of microvessel counts.ResultsLp(a)‐loaded sponges gave significantly higher counts than those loaded with the Lp(a)–anti‐Lp(a) antibodies complex, which overlapped those treated with PBS. The angiogenic response was similar to that obtained with basic fibroblast growth factor, a well‐known angiogenic molecule.ConclusionThese data suggest that Lp(a) is capable of inducing angiogenesis in vivo, which might account for its ability to enhance and support atherosclerosis.
Regulation of iron metabolism in the acute‐phase response: interferon γ and tumour necrosis factor α induce hypoferraemia, ferritin production and a decrease in circulating transferrin receptors in cancer patients
Authors: Feelders  , Vreugdenhil  , Eggermont  , Kuiper‐Kramer  , Van Eijk  , Swaak  
Published: March 2003

BackgroundThe acute‐phase response and anaemia of chronic disease are characterized by hypoferraemia associated with an increased ferritin synthesis, which might be mediated by the activated cytokine cascade.MethodsWe examined the prolonged effects of isolated limb perfusion (ILP) with recombinant human tumour necrosis factor α (rTNF), recombinant human interferon γ (rIFN‐γ) and melphalan on interleukin (IL) 6 and acute‐phase protein levels, iron status and serum transferrin receptor (sTfR) levels in 12 patients with melanoma or sarcoma. Patients were treated with ILP during 90 min after pretreatment with rIFN‐γ during 2 days.ResultsAfter ILP, leakage of TNF resulted in systemic peak levels at 3 min followed by an increase in IL‐6 with maximum levels at 4 h. C‐reactive protein (CRP) rose at 4 h to peak levels at day 2, whereas α1‐antitrypsin and α1‐acid glycoprotein increased to maximum levels at day 3. Albumin and transferrin levels decreased after ILP and recovered after day 2. Serum iron and sTfR levels decreased during pretreatment and after ILP to minimum levels at 8 h and day 1 respectively. This was associated with an increase in serum ferritin levels, which paralleled CRP values.ConclusionsOur data point to a central role for the cytokine network in the modulation of iron metabolism in the acute‐phase response and anaemia of chronic disease. TNF, possibly via induction of IL‐6, and IFN‐γ induce hypoferraemia, which may in part result from a decrease in tissue iron release based on a primary stimulation of ferritin synthesis. The fall in sTfR levels may reflect an impaired erythroid growth and/or TfR expression mediated by TNF and IFN‐γ.