bluuebunny/crossref_metadata_2025 huggingface dataset:
Activity and satiation state in Pterostichus melanarius: an experiment in different agricultural habitats
Authors: Fournier Elisabeth , Loreau Michel
Published: March 2003

1. A capture–recapture experiment was conducted to examine the effects of satiation state on the activity and foraging efficiency of the carabid beetle Pterostichus melanarius Ill., in four different habitats (a hedge, a transition zone between the hedge and the adjacent wheat crop, the margin of the wheat crop, and the centre of the wheat crop) in an agricultural ecosystem in France.

2. Prey biomass and density decreased from the centre of the hedge to the crop margin and to the centre of the crop, where prey density was low but prey biomass was moderate. Starved and satiated beetles were released in circular enclosures and recaptured using pitfall traps for 6 days.

3. Immediately after release, starved P. melanarius were significantly more active than satiated beetles, but this difference disappeared after the first day. At each recapture date, starved individuals had gained weight whereas satiated individuals had lost weight. The analysis of activity and weight variation at the end of the first day indicated that the centre of the crop seemed to be the most favourable habitat for starved individuals to find food rapidly, whereas the behaviour of satiated individuals was identical in all habitats.

4. This experiment shows that habitat use of P. melanarius is flexible. The results are discussed in the context of the classical view of foraging behaviour in carabid beetles. The activity and foraging efficiency in P. melanarius in different habitats can be explained as the result of the interaction between individual satiation state, prey availability in the habitat, and particular preferences of the species.
Holly leaf‐miners on two continents: what makes an outbreak species?
Authors: Eber Sabine , Smith Hugh P. , Didham Raphael K. , Cornell Howard V.
Published: March 2003

1. Some herbivore species periodically undergo damaging, high‐density outbreak phases followed by less damaging low‐density phases. Others maintain steady, low to moderate density levels that do little damage to their hosts.

2. Two closely related holly leaf‐miner species were compared that share many ecological traits and have very similar life cycles, but only one of which exhibits outbreaks. Phytomyza ilicicola in the eastern U.S.A. varied widely in mortality and infestation levels, reaching local densities of over 10 mines per leaf. In contrast, Phytomyza ilicis in the U.K. showed low infestation and high mortality at all sites. Using data from the literature and from field studies, the factors responsible for these contrasting dynamics were sought.

3. Phytomyza ilicicola oviposits into the leaf lamina, and experiences weak larval competition only at high densities. Phytomyza ilicis oviposits into the leaf midrib, which leads to high mortality of young larvae before mine formation. Multiply mined leaves were therefore very common in P. ilicicola but rare in P. ilicis.

4. Differences in the parasitoid complexes of the two systems accounted for further differences in survival to adulthood. The main (larval) parasitoid, which was found to impose high, density‐dependent mortality on P. ilicis, is missing on P. ilicicola. It is replaced by an egg–pupal parasitoid, which varies in its impact at differe∼t sites. Multiple emergence of adults from multiply mined leaves is therefore widespread in P. ilicicola but does not occur in P. ilicis.

5. The differences in oviposition behaviour and in the parasitoid complexes are likely to allow P. ilicicola to outbreak when habitat conditions are favourable, while P. ilicis is always tightly regulated.
Assessment of the relative impact of different natural enemies on population dynamics of the grain aphid Sitobion avenae in the field
Authors: Plantegenest M. , Pierre J. S. , Dedryver C. A. , Kindlmann P.
Published: March 2003

1. A detailed population dynamics model was devised to provide a tool for integrated pest management against the cereal aphid Sitobion avenae on winter wheat.

2. This model allowed investigation of the relative impact of different natural enemies on aphid population dynamics.

3. The output of the model was compared with a set of data collected in the western part of France from 1976 to 1986.

4. Fungal diseases accounted for 75% of the reduction in peak aphid density and were the key factor acting on aphid dynamics in this region.

5. This study highlights the importance of detailed population dynamics modelling of keystone species, like aphids, for elucidation of the relations between the keystone species and other species associated in the ecosystem.
Effects of larval competition on survival and growth in Mediterranean fruit flies
Authors: Dukas Reuven , Prokopy Ronald J. , Duan Jian Jun
Published: March 2003

1. Larval success was compared when one, two, or three egg clutches were laid in kumquat fruits (≈ 10 ml in volume) either successively on the same day or at the rate of one clutch per day.

2. Increased clutch density was associated with a significant decrease in larval survival rate and non‐significant decreases in larval growth rate and pupal mass.

3. Larval and pupal parameters showed significantly larger variance when clutches were laid on successive days than on the same day, suggesting a competitive advantage for older larvae over younger larvae.

4. The results suggest that, in small fruit, reduced fitness due to larval competition may act against possible fitness benefits due to social facilitation among adult females, hence reducing the likelihood of non‐linear population dynamics caused by processes such as the Allee effect.
Influence of atmospheric carbon dioxide enrichment on induced response and growth compensation after herbivore damage in Lotus corniculatus
Authors: Bazin Alain , Goverde Marcel , Erhardt Andreas , Shykoff Jacqui A.
Published: March 2003

Abstract 1. Plant growth and chemical defence compounds in four Lotus corniculatus genotypes exposed to factorial combinations of ambient and elevated carbon dioxide, and herbivory by caterpillars of Polyommatus icarus were measured to test the predictions of the carbon/nutrient balance hypothesis.

2. Shoot and root biomass, allocation to shoots versus roots, and carbon‐based defence compounds were greater under elevated carbon dioxide. Pupal weight of P. icarus was greater and development time shorter under elevated carbon dioxide.

3. Herbivory decreased shoot growth relative to root growth and production of nitrogen‐based defence (cyanide). Young leaves contained more defence compounds than old leaves, and this response depended on carbon dioxide and herbivory treatments (significant interactions).

4. Genotype‐specific responses of plants to carbon dioxide and herbivory were found for the production of cyanide. Furthermore, maternal butterfly‐specific responses of caterpillars to carbon dioxide were found for development time. This suggests the existence of genetic variation for important defence and life‐history traits in plants and herbivores in response to rising carbon dioxide levels.
Host utilisation by moth and larval survival of pine processionary caterpillar Thaumetopoea pityocampa in relation to food quality in three Pinus species
Authors: Hódar José A. , Zamora Regino , Castro Jorge
Published: March 2003

Abstract 1. The work reported here analysed host utilisation by the pine processionary moth Thaumetopoea pityocampa (Lepidoptera: Thaumetopoeidae), the relationship between moth oviposition patterns and larval performance, the chemical characteristics of the plant in relation to the performance of different larval instars, and the role of these factors in the outbreak capacity of the species. In order to do this, a combination of field and laboratory techniques was used to study three pine species differing in nutritional characteristics.

2. Moths oviposited in the three pine species analysed, although cluster pine received a lower number of batches. Late‐instar larvae were able to feed on all three pine species, however first‐instar larvae developed on Scots and black pine but died on cluster pine. Consequently, oviposition in cluster pine can be considered an oviposition mistake, and indicates that moths are rather unselective when ovipositing on different pine species.

3. Chemical analysis of needles suggested that the quantity of nitrogen was the main factor responsible for the difference in survival of larvae.

4. The oviposition pattern of the moth and the larval susceptibility to food quality in Thaumetopoea pityocampa agree with the theory that unselective oviposition of the moth is a precondition for eruptive dynamics in phytophagous insects.

5. The success of the larvae depends mainly on the probability of the moth finding a suitable host. This probability is determined strongly by the changes of structure and coverage in Mediterranean pine woodlands, due to human management.
Density‐mediated responses of bark beetles to host allelochemicals: a link between individual behaviour and population dynamics
Authors: Wallin Kimberly F. , Raffa Kenneth F.
Published: March 2003

Abstract 1. Bark beetles (Coleoptera: Scolytidae) accept or reject host conifers based partly on concentrations of phloem monoterpenes. They colonise trees in aggregations, in response to pheromones that attract flying beetles to trees undergoing colonisation. A series of entry and gallery construction assays was conducted to determine whether responses by individual beetles to monoterpenes are altered by pheromones and/or the presence of other beetles.

2. Entry into the amended media byIps piniand the length of time until entry were not influenced by the presence of aggregation pheromones.

3. Entry into amended media was influenced by the presence of other beetles on the surface of, or constructing galleries in, the substrate. The effects of alpha‐pinene and limonene on host entry behaviour were mediated by the density of beetles on the surface of the assay arena, and by the density of beetles constructing galleries within the medium.

4. The percentage of beetles entering medium amended with higher concentrations of monoterpenes increased with increased density of beetles on the surface of the assay arena, until a threshold density of three or four beetles per assay arena, after which entrance rate declined.

5. The presence of other beetles constructing galleries elicited more rapid entry by the test beetles.

6. Gallery lengths were generally higher in the presence of aggregation pheromones.

7. Gallery lengths increased with increased density of beetles within the assay arena.

8. These results suggest a link between the density of bark beetles and responses of individuals. This linkage may partially explain behavioural changes observed during population eruptions.
Conspicuous colouration attracts prey to a stationary predator
Authors: Hauber Mark E.
Published: March 2003

Abstract1. Conspicuous body colouration is counter‐intuitive in stationary predators because sit‐and‐wait tactics frequently rely on concealed traps to capture prey. Consequently, bright colours and contrasting patterns should be rare in predators using traps as they may alert potential prey. Yet, some orb‐weaving spiders are brightly coloured and contrastingly patterned. How can conspicuousness of trap‐building sit‐and‐wait predators be favoured by natural selection?

2. Observations of spiny spidersGasteracantha fornicatain north‐eastern Australia showed that the size of spiders relative to their orb webs correlated positively with relative prey numbers already captured in their webs. A possible explanation is that the relatively larger appearance of the yellow–black striped dorsal surface of this spider attracts more visually oriented prey items. Prey attracted to webs may get trapped, thereby increasing the spiders' foraging success.

3. To test this hypothesis for the function of conspicuous body colouration, a field experiment was conducted that documented the prey capture rates of spiny spiders after manipulating or sham‐manipulating their appearance.

4. As predicted, spiders that were dyed black on their striped dorsal surface caught relatively fewer prey items than did control spiders. Thus, conspicuous dorsal body colouration may be adaptive in spiny spiders because it increases foraging success and, presumably, survival rates and reproductive outputs. Overall, these data support thecolour‐as‐prey‐attractanthypothesis in a stationary, trap‐building predator.
A comparative study of larval cannibalism in three species of ladybird
Authors: Michaud J. P.
Published: March 2003

Abstract.1. Cannibalism was studied under laboratory conditions in three species of Coccinellidae (Coleoptera):Cycloneda sanguinea,Olla v‐nigrum, andHarmonia axyridis. Larval cannibalism varied among species,C. sanguinea >H. axyridis ≥ O. v‐nigrum.

2. Larvae of all species cannibalised more in response to reduced food availability (14 h starvation daily) than in response to reduced food quality (dryEphestiaeggs).

3. Larvae ofH. axyridiscannibalised siblings at lower rates than non‐siblings, but larvae ofC. sanguineaandO. v‐nigrumdid not. Rates of cannibalism increased significantly with increasing size disparity among larvae of all three species.

4. Cannibalism inC. sanguineaandH. axyridis, but not inO. v‐nigrum, increased with larval density, suggesting that not all attacks on conspecifics are driven by hunger.

5. Costs, not benefits, were the predominant effects of exclusively and partially cannibalistic diets. A diet of conspecific eggs yielded survival equivalent to theEphestiaegg diet forH. axyridisandO. v‐nigrum, but developmental time was extended and adults were smaller. Larvae ofC. sanguineahad superior survival and faster development on conspecific eggs than on theEphestiaegg diet. OnlyH. axyridislarvae survived as well on diets comprised exclusively or partially of conspecific larvae as onEphestiaeggs, although they developed more slowly.
Flight activity of adult stoneflies in relation to weather
Authors: Briers Robert A. , Cariss Helen M. , Gee John H. R.
Published: March 2003

Abstract. 1. Dispersal of adult aquatic insects between streams may have important consequences for local and regional population dynamics, but little is known about how dispersal is affected by weather conditions.

2. The influence of meteorological variables on flight activity of adult stoneflies (Plecoptera: Leuctridae, Nemouridae, and Chloroperlidae) was investigated using Malaise traps adjacent to three upland streams in the Plynlimon area of mid Wales, U.K.

3. Numbers of adult stoneflies captured weekly in the traps were related positively to air temperature and related negatively to wind speed. Meteorological conditions during daylight showed stronger relationships with flight activity than did conditions at night.

4. There was inter‐site variation in the strength of weather effects on stonefly flight. Wind speed was significant at only one site, which had higher average wind speed than the other sites.

5. Annual variation in weather conditions during adult flight periods may result in varying extent of dispersal between sites, influencing community dynamics over a wide area.
Skewed sex ratios and multiple founding in galls of the oak apple gall waspBiorhiza pallida
Authors: Atkinson Rachel J. , Brown Gordon S. , Stone Graham N.
Published: March 2003

Abstract.1. The gall waspBiorhiza pallida(Hymenoptera: Cynipidae) reproduces by cyclical parthenogenesis. The adults of the sexual generation develop within galls (oak apples) that contain many larval cells.

2.Folliot [(1964) Annales Des Sciences Naturelles: Zoologie, 12, 407–564]found asexual generation females to be of three reproductive types. Androphores produce only sons, gynophores produce only daughters, and gynandrophores produce both sons and daughters. In nature, most oak apples give rise to either only males or only females but a proportion produces both sexes. These mixed‐sex galls could result either from eggs laid by one or more gynandrophores or from eggs laid by androphores and gynophores developing within a single gall (multiple founding).

3. Here the frequency of mixed‐ and single‐sex galls was quantified, and morphological and genetic analyses were carried out on the adults emerging from 10 galls to determine the frequency of multiple founding inB. pallida.

4. Seventy‐five per cent of 627 galls yielded only one sex. The majority of the remaining 25% had a highly skewed sex ratio. Low genetic variation inB. pallidalimited the application of allozyme‐based genetic techniques, however seven of the 10 galls analysed in detail, including mixed‐sex galls, appeared to have been multiply founded. Contributions by the different foundresses in multiply founded galls were highly skewed.

5. The significance of multiple founding is discussed in the light of possible adaptive scenarios (reduction of parasitoid‐induced mortality, avoidance of local stochastic extinction and inbreeding) and possible competition for oviposition sites.
Dendrolimus sibiricus in the coniferous forests of European Russia at the beginning of the twenty‐first century
Authors: Gninenko Yu. I. , Orlinskii A. D.
Published: March 2003

The Siberian conifer pest Dendrolimus sibiricus is slowly spreading westwards. It crossed the Urals at the beginning of the twentieth century and reached the Republic of Udmurtiya by the 1950s. Pheromones developed to support control of the pest in Siberia have been used to monitor for its presence in Russia. Results obtained in 2001 show that the pest is now widespread in the Republic of Mari El (500 km east of Moscow), while isolated individuals have been trapped in the Moscow region. No D. sibiricus were trapped in Tver’ Region (between Moscow and Sankt‐Peterburg).
Absence of association between a common mutation in the methylenetetrahydrofolate reductase gene and the risk of coronary artery disease
Authors: Reinhardt  , Sigusch  , Vogt  , Farker  , Müller  , Hoffmann
Published: March 2003

Background

Elevated total plasma homocysteine levels are associated with an increased risk of coronary artery disease. Plasma homocysteine levels are influenced by nutritional and hereditary factors. A point mutation (cytosin to thymidine substitution; C677→T) in the gene encoding methylenetetrahydrofolate reductase (MTHFR), has been reported to render the enzyme thermolabile and has been associated with elevations in homocysteine levels in homozygous carriers (TT genotype).

Methods

To examine the hypothesis that the T allele (coding for the thermolabile defect of MTHFR) influences the risk of coronary artery disease, we genotyped 340 patients with coronary artery disease and 105 control subjects in whom coronary artery disease was excluded by coronary angiography. Furthermore, we studied the genotype frequency in 104 age‐ and sex‐matched healthy persons as a control group without signs of atherosclerotic disease.

Results

Allele frequencies for C (wild‐type allele) and T allele (mutant allele) were 0.68 and 0.32 respectively in the healthy control subjects, 0.66 and 0.34 respectively in patients with angiographically excluded coronary artery disease and 0.69 and 0.31 respectively in coronary artery disease patients (P = NS). The allele frequencies of the total study population were 0.68 and 0.32.

Conclusion

Our data show that homozygosity for the C677→T mutation in this European population is not associated with increased risk of coronary artery disease. This finding suggests that the C677→T mutation of the MTHFR gene does not represent a marker for increased cardiovascular risk.
In vitro effects of growth hormone (GH) and insulin‐like growth factor I and II (IGF‐I and ‐II) on chromosome fragility and p53 protein expression in human lymphocytes
Authors: Cianfarani  , Tedeschi  , Germani  , Prete  , Rossi  , Vernole  , Caporossi  , Boscherini
Published: March 2003

Background

We have reported previously that growth hormone (GH) therapy increases cell radiosensitivity; in this study we tested whether GH itself or IGFs induce chromosome aberrations and investigated the expression of p53 protein in response to DNA damage.

Methods

Human peripheral blood lymphocytes were incubated with GH (100 and 1000 μg L−1), insulin‐like growth factor I (IGF‐I; 150 and 1000 μg L−1) and IGF‐II (600 and 1200 μg L−1) for 24 h. The radiomimetic agent bleomycin (BLM; 5 μg mL−1) was added in the last 3 h. Cytogenetic analysis was performed by assessing the percentages of damaged cells (%DC) and chromosome aberrations (%CA). The expression of p53 was investigated by flow cytometric assay using the monoclonal antibody DO‐7, and expressed as percentage positive cells and mean fluorescence intensity.

Results

BLM significantly increased both percentage DC and percentage CA and p53 expression (P < 0.01). The %DC was unaffected by the tested peptides. IGF‐I (150 μg L−1) increased spontaneous percentage CA (P < 0.01). All peptides further increased the BLM‐induced chromosome breakage: GH 100 and 1000 μg L−1 by 30% and 73% respectively, IGF‐I 150 and 1000 μg L−1 by 41% and 96% respectively and IGF‐II 600 and 1200 μg L−1 by 89% and 45% respectively. The spontaneous and BLM‐induced expression of p53 was unaffected by GH, whereas it was significantly increased by IGFs (P < 0.001).

Conclusions

These results indicate that the DNA‐damaging effect of BLM is amplified by GH and, more markedly, IGF‐I and ‐II. IGF‐I and ‐II also stimulate p53 protein expression that, taking part in DNA repair, may counteract the IGF action on genome stability.
Cellular and molecular characteristics of inflammation in chronic bronchitis
Authors: Sun  , Stacey  , Vittori  , Marini  , Bellini  , Kleimberg  , Mattoli
Published: March 2003

Methods

To examine the inflammatory process in chronic bronchitis, we evaluated the cell and cytokine profile in bronchoalveolar lavage fluid from 12 chronic bronchitis patients who smoked, six chronic bronchitis patients who did not smoke, 10 subjects control subjects without pulmonary diseases who smoked and eight control subjects who did not smoke.

Results

Chronic bronchitis patients who smoked had increased numbers of macrophages, neutrophils, eosinophils, mast cells and activated CD8+ T lymphocytes and predominantly expressed interleukin‐8, tumour necrosis factor alpha and interleukin‐2 genes and proteins. The number of macrophages and neutrophils and the expression of interleukin 8 were also increased in control subjects who smoked compared with healthy subjects who did not smoke. Chronic bronchitis patients who did not smoke had increased numbers of eosinophils, mast cells and activated CD4+ T lymphocytes and predominantly expressed interleukin‐5 and granulocyte–macrophage colony‐stimulating factor genes and proteins.

Conclusion

Thus, the cellular and molecular characteristics of the inflammatory process in chronic bronchitis patients who smoke and do not smoke are different, suggesting a different pathogenesis of the disease.
New type of the internalization‐defective low‐density lipoprotein receptor owing to two‐nucleotide deletion (2199delCA or 2201delCA) in Japanese patients with familial hypercholesterolaemia
Authors: Tashiro  , Endo  , Bujo  , Shinomiya  , Morisaki  , Saito
Published: March 2003

Background

In mutations of the low‐density lipoprotein (LDL) receptor gene, the defect of internalization is caused by a mutation in the cytoplasmic domain of the receptor linked with exons 17 and 18, and the O‐linked sugar domain linked with exon 15 has been speculated not to affect the function of the receptor. Here, we describe a novel mutation of the O‐linked sugar domain of the LDL receptor gene, designated familial hypercholesterolaemia (FH)‐Mishima with Japanese pedigree, which resembles but still differs from classical defective internalization cases.

Methods

LDL metabolism was examined in cultured skin fibroblasts from patients. Immunoprecipitation and immunohistochemical techniques were applied for the detection of the receptor protein size and distribution. Screening of the mutant exon(s) of the LDL receptor gene was performed using the polymerase chain reaction–single‐strand conformation polymorphism technique (PCR–SSCP), and sequencing of the mutated alleles was carried out using the dideoxy chain termination method.

Results

LDL‐binding activity at 4°C in skin fibroblasts from patients was similar to normal, but that at 37°C with the ligand decreased time dependently and was lost at 6 h, resulting in the defect of internalization and degradation of LDL. The receptor protein on the cell surface was detected at 4°C by IgG‐C7, an anti‐LDL receptor antibody, but was not detected after incubation with LDL at 37°C. The size of the receptor was 112 kD as determined by immunoprecipitation analysis. A deletion of two nucleotides in exon 15 was detected in the DNA sequence of the LDL receptor gene. The deletion results in a shift of the reading frame after Thr‐713 of the mutant and makes a stop codon at amino acid 759.

Conclusion

Deletion of the two nucleotides caused novel amino acid sequences after the O‐linked sugar domain, which has the ability of sorting on the cell membrane at 4°C, but not at 37°C in vivo, resulting in the complete cessation of activity of the LDL receptor.
Varying very low‐density lipoprotein secretion of rat hepatocytes by altering cellular levels of calcium and the activity of protein kinase C
Authors: Björnsson  , Bourgeois  , Gibbons
Published: March 2003

Background

Calcium antagonists lower plasma levels of lipoproteins and suppress hepatic very low‐density lipoprotein (VLDL) secretion. Similar effects have been observed with the calcium ionophore A23187. We studied further the effect of calcium on VLDL metabolism.

Methods

Hepatocytes from male Wistar rats were isolated and cultured in the presence or absence of calcium‐mobilizing hormones, or compounds that either stimulate or inhibit the activity of protein kinase C. Secreted VLDL (d < 1.006 g mL−1) was isolated by centrifugation (145 000 × g), and lipids and apolipoprotein B were analysed.

Results

VLDL secretion reached maximum in hepatocytes cultured in medium containing calcium 0.8–2.4 mmol L−1. Depleting the cells of calcium by incubating in calcium‐free medium or by treating the cells with the Ca2+‐ATPase inhibitor thapsigargin (5 × 10−7 mol L−1) suppressed lipid secretion to less than 15% of control, and this was accompanied by an increase in cellular levels of triacylglycerol. Calcium loading (medium calcium > 2.4 mmol L−1) suppressed both lipoprotein secretion and cellular levels of lipids, suggesting a reduced overall rate of lipid synthesis. At an extracellular calcium concentration of 0.8 mmol L−1, angiotensin II, vasopressin, endothelin‐1 (10−7 mol L−1) or phenylephrine (10−4 mol L−1) suppressed VLDL secretion (maximum to 37% of control), and elevated medium calcium attenuated this effect. The protein kinase C inhibitor chelerythrine (5 × 10−5 mol L−1) and the protein kinase C activator phorbol 12‐myristate 13‐acetate (PMA) (10−6 mol L−1), suppressed VLDL secretion to 18% and 60% of control, respectively, whereas the protein kinase C‐inactive 4α‐PMA was without an effect. No effect on ketogenesis was observed by these compounds, indicating that suppressed lipid secretion was not due to an enhanced oxidation of lipids.

Conclusions

Hepatic VLDL secretion can be related to changes in hepatocyte levels of calcium and the activity of protein kinase C.
Mutations in the low‐density lipoprotein receptor gene in Swedish familial hypercholesterolaemia patients: clinical expression and treatment response
Authors: Ekström  , Abrahamson  , Wallmark  , Florén  , Nilsson‐Ehle
Published: March 2003

Background

Familial hypercholesterolaemia, an autosomal co‐dominant disorder caused by defects in the low‐density lipoprotein receptor gene, is strongly associated with premature development of cardiovascular disease.

Methods

In this study, we have applied a gene screening method in a population of familial hypercholesterolaemia patients in order to describe the genetic background of the disease in southern Sweden. These patients were studied with the aim of relating the presence of the different mutations to the clinical expression of the disease and to the response to pharmacological treatment.

Results

In 16 out of 21 patients, potentially disease‐causing low‐density lipoprotein receptor gene defects were found, including five not previously described alterations (C240 → F, C122 → stop, C356 → Y, 785insG, 165delG). No defects in apolipoprotein B were found. One group of patients (n = 4) carried the mutation C122 → stop and another group of patients (n = 4) a mutation causing the substitution W66 → G. Patients in the two genotype subgroups were very similar with respect to lipid levels before treatment.

Conclusion

A tendency towards differential susceptibility to treatment with statins was observed for the patient groups, encouraging further comparative studies of heterozygous FH patients.
Circulating leptin has saturable transport into intrathecal space in humans
Authors: Koistinen  , Karonen  , Iivanainen  , Koivisto
Published: March 2003

Background

Leptin is an adipocyte‐derived hormone that is thought to provide a negative feedback signal to control body fat mass by interacting with its hypothalamic receptor. The present study was undertaken to examine the uptake of leptin in cerebrospinal fluid (CSF) space in humans and whether the transport of leptin into CSF space is an active phenomenon or due to free access through the blood–CSF barrier.

Methods

We determined serum and CSF leptin concentrations by radioimmunoassay in 17 men [42 ± 4 years, mean ± SE; body mass index (BMI) 27.3 ± 1.8 kg m−2] and 22 women (40 ± 3 years, BMI 25.1 ± 1.0 kg m−2). The function of the blood–CSF barrier was evaluated by determining the CSF/serum albumin ratio.

Results

Serum leptin concentration was lower in male (5.8 ± 1.6 μg L−1) than in female subjects (13.1 ± 1.7 μg L−1, P = 0.001), whereas the concentrations of leptin in CSF were virtually identical in male (0.34 ± 0.03 μg L−1) and female (0.36 ± 0.03 μg L−1) subjects. Serum leptin was correlated positively with BMI both in men (r = 0.89, P < 0.01, n = 10) and in women (r = 0.61, P < 0.05, n = 14), whereas no correlation between CSF leptin concentration and BMI was found in either group. The CSF/serum leptin ratio correlated negatively with serum leptin concentration both in men (r = −0.93, P < 0.001) and in women (r = −0.77, P < 0.001) and with BMI both in men (r = −0.75, P = 0.02, n = 10) and in women (r = −0.64, P < 0.02, n = 14). The CSF/serum albumin ratio was not correlated with the CSF/serum leptin ratio in either group. CSF leptin concentrations and the CSF/serum leptin ratio were virtually identical in subjects with impaired and normal blood–CSF barrier function.

Conclusion

Thus, our data support the presence of a saturable and active transporter of leptin from circulation into intrathecal space.
Ureter obliteration transiently depresses erythropoietin production
Authors: Nečas  , Ponka
Published: March 2003

Background

The erythropoietin (EPO) gene is activated in peritubular cells of the renal cortex in response to hypoxia and EPO is secreted into the circulation. Oxygen tension in the venous blood normally determine EPO elaboration, and, therefore, oxygen consumption in the kidney appears to be an essential part of the oxygen‐sensing physiological mechanism. As renal oxygen consumption is closely linked to urine production, we have compared responsiveness of the EPO gene to diminished oxygen supply in the normal kidney with that of the hydronephrotic kidney, resulting from ureter ligation.

Methods

Erythropoietin mRNA was determined in RNA extracted from murine kidneys at various times up to 61 days after ureter ligation. Mice were exposed to hypoxia for 4 h before being killed.

Results

Unilateral ureter ligation significantly decreased EPO mRNA levels in the affected kidney. However, the ability to increase EPO mRNA recovered between days 4 and 22, despite persisting ureter ligation.

Conclusion

Our results demonstrate a dissociation between the excretory functions of the kidney and EPO production. Moreover, they show an early but transient suppression of EPO gene responsiveness to hypoxia after ureter ligation.
Prandial glucose regulation and cardiovascular disease in Type 2 diabetes
Authors: Kuusisto  , Laakso
Published: March 2003

Type 2 diabetes is associated with an increased risk for cardiovascular disease. In recent years, prospective studies have indicated that, in addition to conventional risk factors, glycaemic control of diabetes predicts cardiovascular disease in both middle‐aged and elderly patients with Type 2 diabetes. However, there are no consistent data from different studies to indicate that postprandial glucose is a better predictor for cardiovascular risk than fasting glucose level. Although no clinical trials are available to show that improving glycaemic control prevents cardiovascular mortality and morbidity, recent studies imply that hyperglycaemia in patients with Type 2 diabetes should be treated more intensively than recommended by current guidelines
The effects of ABT‐229 and octreotide on interdigestive small bowel motility, bacterial overgrowth and bacterial translocation in rats
Authors: Nieuwenhuijs  , Van Duijvenbode‐Beumer  , Verheem  , Visser  , Verhoef  , Gooszen  , Akkermans
Published: March 2003

Background

Interdigestive small bowel motility has a regulatory function on the microflora of the upper small bowel. Here we investigate the effects of ABT‐229 and octreotide on morphine‐induced dysmotility, the accompanying bacterial overgrowth and bacterial translocation.

Methods

Rats were fitted with jejunal myoelectrodes and a subcutaneous cannula for continuous infusion of saline or morphine. Fasting motility was measured for 6 h on four occasions: one control measurement (day 0) and three measurements on consecutive days (days 1–3) while receiving saline alone (group A), morphine alone (group B), saline + ABT‐229 (group C), morphine + ABT‐229 (group D), saline + octreotide (group E) or morphine + octreotide (group F). Samples from the mesenteric lymph node complex (MLN), liver, spleen, duodenum and ileum were taken for quantitative microbial culturing on day 4.

Results

Neither ABT‐229 nor octreotide increased the number of propagated activity fronts during saline infusion. During morphine‐induced dysmotility, ABT‐229 induced more propagated activity fronts in group D (13.4, 9.8 and 8.8 per 6 h) than in group B (7.0, 4.5, 3.8 per 6 h) on days 1, 2 and 3 (P < 0.05 for all days) Octreotide did not induce more propagated activity fronts. Disruption of small bowel motility by morphine led to bacterial overgrowth in the duodenum. ABT‐229 and octreotide did not reduce the bacterial growth levels. The total incidence of bacterial translocation was significantly higher in the morphine‐treated animals than in the saline‐treated animals. Neither ABT‐229 nor octreotide reduced the bacterial translocation incidence. The number of propagated activity fronts on day 3 and duodenal bacterial growth correlated significantly in groups A, E and F.

Conclusions

ABT‐229, but not octreotide, reduced morphine‐induced dysmotility. Small bowel bacterial overgrowth and bacterial translocation were not prevented. Fasting small bowel motility has a regulatory function on the intestinal microflora of the upper small bowel.
Expression of genes involved in calcium absorption in human duodenum
Authors: Walters  , Howard  , Lowery  , Mawer  , Legon
Published: March 2003

Background

The role of vitamin D metabolites in the regulation of expression of genes involved in dietary calcium absorption by the human intestine remains poorly understood despite much work in animals.

Materials and methods

To investigate this, we measured the expression of transcripts for two of these genes, calbindin‐D9k and the basolateral membrane calcium pumping ATPase, PMCA1, in duodenal endoscopic biopsies from 40 subjects. Northern blots were hybridized with previously characterized probes, and the signal was quantified by phosphor imaging. These transcript levels were related to circulating vitamin D metabolites and also analysed according to the vitamin D receptor gene TaqI polymorphism determined in DNA from blood.

Results

Plasma 1,25‐dihydroxycholecalciferol correlated significantly with calbindin‐D9k RNA (r = 0.4, P < 0.02) but not with PMCA1. Plasma 25‐OH‐cholecalciferol was not correlated with transcripts for either gene and, furthermore, the mean levels of these transcripts did not differ significantly when grouped by vitamin D receptor genotype.

Conclusion

In normal humans, 1,25‐dihydroxycholecalciferol has a small but significant relationship to duodenal expression of calbindin‐D9k, but not to PMCA1 expression.
Polymorphisms of the endothelial nitric oxide synthase gene — no consistent association with myocardial infarction in the ECTIM study
Authors: Poirier  , Mao  , Mallet  , Nicaud  , Herrmann  , Evans  , Ruidavets  , Arveiler  , Luc  , Tiret  , Soubrier  , Cambien
Published: March 2003

Background

Our aim in the present study was to determine whether endothelial NO synthase gene (ecNOS) polymorphisms are associated with myocardial infarction (MI).

Methods

Forty chromosomes from patients with MI were screened for polymorphisms of the ecNOS gene using polymerase chain reaction–single‐strand conformation polymorphism (PCR–SSCP) analysis and sequencing. Ten polymorphisms were detected: three in the 5′ flanking sequence at positions −1474, −924 and −788, two in coding sequences 774C → T (silent) and G894 → T (Glu‐298 → Asp) and five in introns 2, 11, 12, 22 and 23. Five hundred and thirty‐one patients with MI and 610 control subjects recruited in France and Northern Ireland in the ECTIM study were genotyped for these polymorphisms.

Results

Glu‐298 homozygotes were more frequent among patients with MI than in control subjects in the French population [OR = 1.47 (1.03–1.97), P < 0.009], but no such difference was observed in Northern Ireland. No significant difference between cases and control subjects was detected for the other polymorphisms. Our search for a possible association of the combination of ecNOS polymorphisms with MI by logistic regression analysis was also negative.

Conclusions

We have explored a set of polymorphisms of the ecNOS gene in a large case–control study of MI and found that the polymorphisms were not consistently associated with MI.
Evidence of circadian rhythm in low‐density lipoprotein apoB catabolism and its impact on the estimation of kinetic parameters
Authors: Weryński  , Nahorski  , Berglund  , Ericsson  , Angelin  , Eriksson
Published: March 2003

Background

Compartmental models with constant parameters are commonly used in kinetic analysis of low‐density lipoproteins (LDLs). Recent studies in animals have demonstrated the existence of circadian rhythms (CRs) in cholesterol synthesis and LDL catabolism. In this study, we investigated the possible existence of a CR in the fractional catabolic rate (FCR) of LDL apoB in man.

Materials and methods

Radioactivity data from 45 turnover studies using 125I‐labelled LDL apoB were analysed. In a preliminary analysis the pattern of radioactivity decay was investigated. Kinetic analysis was performed by using one‐ and two‐compartment models with constant parameters (steady‐state, SS, analysis). Parameters were estimated by the use of the whole data set, which included frequent sampling during the first day of the turnover study, or the once‐a‐day data, taken at 08.00 h . The selection of once‐a‐day data allowed elimination of the impact of a CR on parameter evaluation. Furthermore, non‐steady‐state (NSS) analysis was performed in which the FCR of LDL apoB was calculated as a function of time. In one additional subject, the FCR of LDL apoB was calculated separately for the day and the night using the urine‐to‐plasma (U/P) radioactivity ratio.

Results

The presence of a CR in LDL apoB catabolism, with higher FCR values during the day than during the morning, was demonstrated by the NSS analysis and confirmed by LDL apoB calculation from the U/P ratio. The SS analysis with the whole and the once‐a‐day data sets resulted in similar average FCR of apoB values (0.329 ± 0.076 and 0.321 ± 0.071 respectively) when the two‐compartment model was used. Thus, a CR appeared to have little impact on the average FCR of apoB estimation. However, frequent sampling used in the hope of improving parameter estimation accuracy actually resulted in deterioration of the intercompartmental parameter estimators.

Conclusion

The fractional catabolic rate of LDL apoB exhibited a circadian rhythm with higher FCR values during the day than during the morning. The presence of a CR had, however, a limited impact on the overall FCR of apoB values.
Myocardial bradykinin production during coronary balloon angioplasty in humans
Authors: MacCarthy  , Prendergast  , Williams  , Penny  , Shah
Published: March 2003

Background

Recent studies have implicated the peptide bradykinin as a potential trigger of ischaemic preconditioning, the phenomenon whereby a brief episode of myocardial ischaemia induces an increased tolerance to subsequent more prolonged ischaemia. Brief myocardial ischaemia occurring during percutaneous transluminal coronary balloon angioplasty in humans is reported to be capable of inducing preconditioning.

Design

We studied the intracardiac production of bradykinin in eight patients (seven men, mean age 53.5 years) undergoing elective percutaneous transluminal coronary angioplasty for a single left anterior descending coronary artery stenosis. Paired blood samples were obtained from the coronary sinus and the proximal aorta at baseline, immediately before balloon deflation after a 2‐min inflation, and at 1, 3 and 5 min post deflation. Bradykinin levels were measured by radioimmunoassay.

Results

There was no significant change either in aortic or coronary sinus bradykinin levels at any time point.

Conclusions

Intracardiac production of bradykinin is unlikely to be a trigger for ischaemic preconditioning after brief myocardial ischaemia in humans.
Antroduodenal motility and small bowel transit during continuous intraduodenal or intragastric administration of enteral nutrition
Authors: Ledeboer  , Masclee  , Coenraad  , Vecht  , Biemond  , Lamers
Published: March 2003

Background

Gastrointestinal intolerance is observed more frequently during intraduodenal (ID) tube feeding than during intragastric (IG) feeding, possibly because it evokes a stronger gastrointestinal response and accelerates small bowel transit. We have investigated whether the accelerated small bowel transit during ID feeding results from alterations in antroduodenal motility pattern.

Design

The effect of IG and ID infusion of a polymeric diet (Nutrison, 125 kcal h−1) on antroduodenal motility, small bowel transit time (SBTT) and gastrointestinal hormone release was studied in nine healthy subjects. These subjects were studied on three occasions for 6 h during fasting, continuous IG or ID feeding.

Results

Phase III recurrence time was significantly prolonged during IG feeding compared with fasting (240 ± 51 vs. 136 ± 24 min; P < 0.05). None of the subjects had recurrence of phase III during ID feeding; the fed motor pattern remained present. Parameters of fed motility (mean amplitude and motility index) were not significantly different between IG and ID feeding, although the frequency of antral and duodenal contractions was lower during ID than during IG feeding. SBTT was significantly accelerated during ID compared with IG feeding and with fasting (58 ± 8 vs. 73 ± 9 and 83 ± 10 min respectively; P < 0.05). Plasma cholecystokinin (CCK) and pancreatic polypeptide (PP) levels were significantly higher during ID than during IG feeding. Peptide YY (PYY) levels were significantly higher during ID than during fasting, but not during IG feeding

Conclusions

During intraduodenal feeding, a fed motility pattern is preserved, whereas during intragastric feeding transition from a fed to a fasting motor pattern is observed in over 50% of the subjects. These differences may be related to augmented hormone release during intraduodenal feeding.
Potent synergistic effect of sho‐saiko‐to, a herbal medicine, during vaccine therapy in a murine model of hepatitis B virus carrier
Authors: Akbar  , Yamamoto  , Abe  , Ninomiya  , Tanimoto  , Masumoto  , Michitaka  , Horiike  , Onji
Published: March 2003

Background

Traditional herbal medicine, sho‐saiko‐to (TJ‐9), improves subjective symptoms, and a recently developed vaccine therapy reduces the viral replication in some chronic hepatitis B virus (HBV)‐carriers. The study presented here considers the impact of a combination of vaccine therapy and TJ‐9 and the mechanism underlying the therapeutic effect of TJ‐9.

Materials and methods

HBV‐transgenic mice (HBV‐Tg) expressing similar levels of HBV‐related antigens and HBV DNA were used as an animal model of HBV‐carrier state, and were assigned to receive either a TJ‐9‐enriched diet or a monthly injection of vaccine containing hepatitis B surface antigen (HBsAg), or both, for 12 consecutive months.

Results

Twelve months after starting the therapy, 9% (1 of 11), 61% (11 of 18), and 100% (10 of 10) of HBV‐Tg receiving only the TJ‐9‐treatment, only the monthly vaccine, and both the TJ‐9 and vaccine, respectively, responded to therapy and became completely negative for HBsAg. Spleen lymphocytes and antigen presenting cells (APC) from TJ‐9‐treated HBV‐Tg produced significantly higher levels of IgM, IgG and antibodies to keyhole limpet hemocyanin (KLH) and showed significantly higher stimulatory capacity in allogenic mixed leukocyte reaction (MLR) compared with the spleen cells and APC from HBV‐Tg receiving normal diet without TJ‐9 (P < 0.05).

Conclusion

These data confirm the therapeutic role of TJ‐9 during HBV infection and inspire optimism of a widespread use of TJ‐9 during immune therapies.
Performance of the [13C]‐acetate gastric emptying breath test during physical exercise
Authors: Van Nieuwenhoven  , Wagenmakers  , Senden  , Brouns  , Brummer
Published: March 2003

Background

The gastric emptying rate of liquids can be determined non‐invasively using the [13C]‐acetate breath test at rest. The aims of our study were to validate this test during physical exercise against the double‐sampling method and to evaluate the time needed for intestinal absorption and the delay between absorption and appearance of 13CO2 in breath, both at rest and during exercise.

Design

Fifteen well‐trained male subjects were investigated. Gastric emptying was determined simultaneously measuring the 13CO2 breath enrichment after intragastric administration of 0.5 L of carbohydrate solution with 150 mg of [13C]‐acetate added and by the double‐sampling technique (n = 9). In separate tests, 150 mg of [13C]‐acetate was also applied intraduodenally and intravenously (n = 6), both at rest and during exercise. Time‐to‐peak (TTP) 13CO2 enrichment was determined using a curve fit and was considered as the parameter for gastric emptying.

Results

TTP enrichment derived from the breath test significantly correlated with the gastric emptying half‐time obtained from the gastric aspirates. During exercise, median TTP enrichment values after intragastric, intraduodenal (i.d.) and intravenous (i.v.) administration of [13C]‐acetate were 22.3, 10.3 and 5.4 min respectively. During exercise, i.d. and i.v. values were reached significantly earlier than at rest.

Conclusion

The [13C]‐acetate breath test can be used as a non‐invasive method to determine relative gastric emptying rates of liquids during exercise, but the results are influenced by the rate of absorption and the time needed for subsequent oxidation of [13C]‐acetate and exhalation of 13CO2.