bluuebunny/crossref_metadata_2025 huggingface dataset:
Targeting of malate synthase 1 to the peroxisomes of Saccharomyces cerevisiae cells depends on growth on oleic acid medium
Authors: Kunze Markus , Kragler Friedrich , Binder Maximilian , Hartig Andreas , Gurvitz Aner
Published: March 2003

The eukaryotic glyoxylate cycle has been previously hypothesized to occur in the peroxisomal compartment, which in the yeast Saccharomyces cerevisiae additionally represents the sole site for fatty acid β‐oxidation. The subcellular location of the key glyoxylate‐cycle enzyme malate synthase 1 (Mls1p), an SKL‐terminated protein, was examined in yeast cells grown on different carbon sources. Immunoelectron microscopy in combination with cell fractionation showed that Mls1p was abundant in the peroxisomes of cells grown on oleic acid, whereas in ethanol‐grown cells Mls1p was primarily cytosolic. This was reinforced using a green fluorescent protein (GFP)–Mls1p reporter, which entered peroxisomes solely in cells grown under oleic acid‐medium conditions. Although growth of cells devoid of Mls1p on ethanol or acetate could be fully restored using a cytosolic Mls1p devoid of SKL, this construct could only partially alleviate the requirement for native Mls1p in cells grown on oleic acid. The combined results indicated that Mls1p remained in the cytosol of cells grown on ethanol, and that targeting of Mls1p to the peroxisomes was advantageous to cells grown on oleic acid as a sole carbon source.
Differential regulation of the Fe‐hydrogenase during anaerobic adaptation in the green alga Chlamydomonas reinhardtii
Authors: Happe Thomas , Kaminski Annette
Published: March 2003

Chlamydomonas reinhardtii, a unicellular green alga, contains a hydrogenase enzyme, which is induced by anaerobic adaptation of the cells. Using the suppression subtractive hybridization (SSH) approach, the differential expression of genes under anaerobiosis was analyzed. A␣PCR fragment with similarity to the genes of bacterial Fe‐hydrogenases was isolated and used to screen an anaerobic cDNA expression library of C. reinhardtii. The cDNA sequence of hydA contains a 1494‐bp ORF encoding a protein with an apparent molecular mass of 53.1 kDa. The transcription of the hydrogenase gene is very rapidly induced during anaerobic adaptation of the cells. The deduced amino‐acid sequence corresponds to␣two␣polypeptide sequences determined by sequence analysis of the isolated native protein. The Fe‐hydrogenase contains a short transit peptide of 56 amino acids, which routes the hydrogenase to the chloroplast stroma. The isolated protein belongs to a new class of Fe‐hydrogenases. All four cysteine residues and 12 other␣amino acids, which are strictly conserved in the active site (H‐cluster) of Fe‐hydrogenases, have been identified. The N‐terminus of the C. reinhardtii protein is markedly truncated compared to other nonalgal Fe‐hydrogenases. Further conserved cysteines that coordinate additional Fe–S‐cluster in other Fe‐hydrogenases are missing. Ferredoxin PetF, the natural electron donor, links the hydrogenase from C. reinhardtii to the photosynthetic electron transport chain. The hydrogenase enables the survival of the green algae under anaerobic conditions by transferring the electrons from reducing equivalents to the enzyme.
Increased serum interferon alpha in HIV–1 associated lipodystrophy syndrome
Authors: Christeff N. , Melchior J.‐C. , De Truchis P. , Perronne C. , Gougeon M.‐L.
Published: March 2003

Abstract Background  A syndrome of lipodystrophy (LD) associated with peripheral lipoatrophy and central/visceral adiposity has been reported in HIV‐1‐infected patients treated by combined antiretroviral therapy (ART). Lipid metabolism is partly regulated by both steroid hormones and cytokines and we have previously reported that dyslipidaemia in LD‐positive men is correlated to an increase in cortisol : DHEA ratio (Christeff et al., AIDS 1999;13:2251). In this study we questioned whether it is also related to cytokine perturbations.

Materials and Methods  A cross‐sectional study was performed on 42 HIV‐1‐positive men on ART, 27 of whom had symptoms of LD, defined by computed tomography scan. Serum cytokines (IFN‐α, TNF‐α, sTNF‐RI, sTNF‐RII, IL‐6, IL‐1β and IL‐2) and lipids [cholesterol, triglycerides (TG) and their subclasses], and apolipoproteins (Apo), were determined.

Results  Serum IFN‐α was markedly increased in LD‐positive compared with LD‐negative men and controls. IL‐6 and TNF‐α concentrations were also significantly elevated in HIV‐positive men compared to controls but the levels of these cytokines did not differ between the two groups of patients. A significant positive correlation was found between accumulation of IFN‐α and increased levels of cholesterol, TG, VLDL cholesterol, VLDL TG, ApoB and ApoB–ApoA1 ratio. A multivariate forward‐performed analysis revealed that IFN‐α is the best marker for lipid perturbations associated to LD, followed by insulin and cortisol : DHEA ratio.

Conclusions  This study demonstrates an association between serum IFN‐α and lipid alterations in LD‐positive men. The concomittant action of IFN‐α and cortisol : DHEA ratio is probably one of the mechanisms responsible for hyperlipidaemia in LD syndrome.
Antenatal determinants of neonatal immune responses to allergens
Authors: Devereux G. , Barker R. N. , Seaton A.
Published: March 2003

Background The environmental factors responsible for recent increases in the prevalence of asthma and atopic disease have been assumed to act after birth. Their possible effects on fetal immune development in utero have not been investigated systematically, although sensitization to allergens may occur before birth.

Objective This prospective study determined whether the risk factors for asthma and atopic disease, namely family history of atopic disease, maternal smoking, birth order, or maternal dietary intake of antioxidant vitamins, exert antenatal effects on the fetal immune system that may predispose to childhood atopy.

Methods The T helper (Th) cell proliferative responses of cord blood mononuclear cells (CBMC) from a sample of 223 neonates, representative of children born to a cohort of 2000 pregnant women, were measured and related to family, maternal and environmental factors associated with the pregnancy.

Results The magnitude of CBMC‐proliferative responses to allergens increased significantly in association with a family history of atopic disease or maternal smoking, and decreased significantly with increasing birth order and high maternal dietary intake of vitamin E. The epidemiological association between birth order and atopy may therefore be a consequence of antenatal influences rather than of protective effects of childhood infections. The association between maternal intake of vitamin E and CBMC responsiveness suggests that diet during pregnancy may influence the fetal immune system in such a way as to modulate the risk of childhood atopy.

Conclusion These results provide a new insight into the aetiology of atopic disease by demonstrating that the maternal environmental risk factors for atopy, diet, birth order and smoking, influence the development of the fetal immune system. This raises the prospect of preventative public health interventions during pregnancy.
The influence of fieldwork on the preferred future practice areas of final year occupational therapy students
Authors: Crowe Michelle J. , Mackenzie Lynette
Published: March 2003

The student fieldwork experience has been recognised as an important influence on the areas of occupational therapy practice pursued by clinicians after graduation. The recruitment patterns of graduate occupational therapists is a key issue, especially in clinical areas such as rural practice and mental health. This study aimed to investigate the future practice preferences of 50 final year occupational therapy students from two occupational therapy schools in New South Wales, in relationship to their fieldwork experience, using a focus group and a survey. General physical dysfunction was the most popular area of future practice for this group. Results suggested that fieldwork influenced students through the programme content, the timing of placements, supervision, and students’ personal responses to their experiences. The study also demonstrated that students use the fieldwork experience to guide their decision to enter an area of practice.
Ultra‐high‐pressure metamorphism in the Dabie Mountains of China
Authors: Mason Roger
Published: March 2003

The Dabie region of central China is host to metamorphic rocks generated at very high pressures below the crust.
Soils – past and present
Authors: Dubbin William
Published: March 2003

‘Lying at the interface of the geosphere, biosphere and hydrosphere, soils occupy a central place in ecosystems, and because of this they are sensitive and detailed indicators of past and present environments.’
Between‐year variation in determinants of offspring survival in the Sand Lizard,Lacerta agilis
Authors: Olsson M. , Madsen T.
Published: March 2003

Life‐history theory predicts that clutch size and offspring size should evolve to an optimal offspring sizevsnumber (OSN) equilibrium.

 Offspring size in Swedish Sand Lizards (Lacerta agilis) decreases up to 60% during a female’s life with a concomitant increase in clutch size; why do female Sand Lizards not produce an offspring of approximately equal size through life, while adjusting clutch size in accordance with available resources?

 Our results show that there is year‐to‐year variation in what factors determine female reproductive success, estimated by the number or proportion of recruits into the second year cohort.

 In a year with relatively poor female growth rate, poor female condition and probably relatively low potential for resource acquisition, females mating with many partners did relatively better than females mating with fewer partners.

 In the poor year, relatively larger offspring survived better than smaller ones.

 In a year with relatively high resource levels, females producing both relatively large young and large clutches were favoured by selection.

 Depending on environmental conditions, female ‘optimal tactics’ may differ between episodes of selection.
Optimal leaf display and biomass partitioning for efficient light capture in an understorey palm, Licuala arbuscula
Authors: Takenaka A. , Takahashi K. , Kohyama T.
Published: March 2003

The effects of leaf display and biomass partitioning on light capture efficiency were examined in a non‐branching understorey palm, Licuala arbuscula, by using a three‐dimensional geometric simulation model. This species has several fan‐shaped laminae, attached on long petioles at a mostly constant deflection angle (DP). The petiole of the youngest leaf was almost vertical, and slanted downwards as it aged.

 The combination of large DP and small Zmax (zenith angle of the oldest leaf’s petiole) maximized light capture for a plant with few leaves; this combination kept the lamina facing in the approximate direction of the zenith with high light intensity. For a plant with many leaves, the combination of large Zmax and small DP increased light capture because it reduced self‐shading.

 For a given total leaf biomass, the plant increased its total leaf area by producing many small leaves. This occurred because the leaf area per unit biomass decreased with increasing biomass per individual leaf. This effect was most pronounced in larger plants. However, an increasing number of leaves intensified self‐shading among leaves. Allocation of biomass to the petioles reduced self‐shading, but decreased leaf area.

 There was an optimal allocation of biomass to petioles and an optimal number of leaves that maximized the crown’s light capture. Greater investment in petioles as the number of leaves increased was the favoured strategy for larger plants.

 In most cases, the leaf geometry and biomass partitioning in the plants were close to the optima predicted by a simulation model developed in this study. There were noticeable differences in a few cases, but the reduction in the crown’s light capture due to these differences was small.
Drought prolongs leaf life span in the herbaceous desert perennial Cryptantha flava
Authors: CASPER B. B. , FORSETH I. N. , KEMPENICH H. , SELTZER S. , XAVIER K.
Published: March 2003

Drought‐deciduous leaves are common in habitats with predictable, seasonal drought, and a reduction in transpirational surface area is generally considered an important drought‐response strategy. Yet leaf demographic responses to unpredictable drought events that can occur at any time during the growing season have been little studied in ecological systems.

 We created drought in a natural population of the herbaceous desert perennial Cryptantha flava (A. Nels.) Payson (Boraginaceae) in north‐eastern Utah, USA, by installing rainout shelters just before and during the early part of the growing season, from 1 March until mid‐June in 1998, and from 1 March until mid‐May in 1999.

Droughted plants exhibited water stress through lower rates of midday photosynthesis and conductance, and by producing leaves with a smaller surface area and greater specific mass than plants exposed to ambient precipitation.

 Under drought, leaf life span increased on flowering stalks and vegetative rosettes and new leaf production decreased, reducing leaf turnover and increasing standing leaf crop in droughted plants.

 A larger number of leaves under drought conditions compensated in area for their smaller size, which means that transpirational surface area was not reduced.

 The reduction in photosynthetic rate and the increase in leaf life span are consistent with a more general pattern in response to other low resource conditions, paralleling leaf‐level responses to shortages of nutrients and light.

 Plants in the drought and ambient precipitation treatments responded to late‐season rainfall with increased leaf production, providing an additional example of developmental plasticity in response to temporal heterogeneity in water availability.
Seed flotation and postflooding germination in tropical terra firme and seasonally flooded forest species
Authors: LOPEZ O. R.
Published: March 2003

Seed flotation, postflooding germination and initial height and expansion rates of seedlings of six terra firme (upland forest) and six seasonally flooded forest (SFF) species from Panama were examined as indicators of their potential for dispersal by water.

 Compared to terra firme species, SFF species had larger seeds with greater volumes and lower seed specific weights, resulting in greater buoyancy.

Across all species, seed specific weight was negatively correlated with initial flotation.

 After 60 days in water, an average of 53% of the seeds of SFF species remained buoyant. In contrast, no seeds of the terra firme species remained buoyant after 15 days. On average more than half the seeds of SFF species germinated after 60 days, while for the terra firme species germination was reduced by 50% after 13 days.

 Seedling expansion rates of SFF species were twice as fast as those of terra firme species. Three weeks after germination, seedlings of SFF species were twice the height of those of terra firme species, a trait which may minimize immersion of the photosynthetic tissue.

 The superior flotation and postflooding germination of SFF relative to terra firme species suggests that dispersal by water is an important adaptation in habitats where flooding is common. Lack of hydrochory among terra firme species may be a key selective filter contributing to the poor species diversity found in SFFs even though saplings and adults may be flood‐tolerant.
The potential costs of flipper‐bands to penguins
Authors: Jackson S. , Wilson R. P.
Published: March 2003

The published literature on the effects of flipper‐bands on penguin ecology is reviewed. Six published studies show the following.

 In Adélie Penguins Pygoscelis adeliae, flipper‐bands directly damaged flippers, increased swimming costs by 24%, decreased survival in the first year after banding by 28%, and may have accelerated decline of a dwindling colony by 3%.

 Adult return rates to colonies among flipper‐banded Adélie, Chinstrap P. antarctica and Gentoo P. papua Penguins decreased by 8%, 12% and 25%, respectively, between single‐ and double‐banded penguins. Juvenile return rates among Gentoo Penguins were reduced by 10·5%. Return rates to the colony among double‐banded King Penguins Aptenodytes patagonicus were 31·3% and 6·7% lower than among single‐banded birds in the first and second years after banding, respectively, and single flipper‐banded birds showed annual survival rates 21·1% lower than those of birds fitted with subcutaneous transponders.

 Among Royal Penguins Eudyptes schlegeli, there were no differences between chick growth, adult over‐winter survival and fledging success between flipper‐banded birds and birds fitted with transponders.

 Adélie Penguin adult annual survival rates were lower among flipper‐banded birds than among unbanded birds.

 On the basis of dive profiles for Adélie Penguins, it is estimated that increased swimming costs of 5% reduce prey contact time by 10%, and of 24% reduce prey contact time by 48%. These estimated ‘knock‐on’ or cumulative costs coupled with the survival and breeding costs shown by the majority of published field studies suggest that data collected on some flipper‐banded populations are biased.

The advantages and disadvantages of an alternative long‐term marking technique, subcutaneously implanted passively interrogated transponder tags, are discussed. Research projects currently testing transponders and flipper‐bands worldwide are listed.
Weight loss increases circulating levels of ghrelin in human obesity
Authors: Hansen Troels Krarup , Dall Rolf , Hosoda Hiroshi , Kojima Masayasu , Kangawa Kenji , Christiansen Jens Sandahl , Jørgensen Jens Otto Lunde
Published: March 2003

objective Ghrelin, a novel endogenous ligand for the GH secretagogue receptor, has been reported to have adipogenic actions and induce weight gain in addition to its GH‐releasing properties. Interestingly, recent data indicate that ghrelin is downregulated in human obesity, which is also known to be accompanied by reduced GH levels.

patients and methods To investigate the influence of weight loss on circulating levels of ghrelin we recruited eight obese women among patients attending a 6‐month weight‐loss course organized by The Danish Heart Association. We measured body composition including computerized tomography as well as fasting plasma ghrelin concentrations before and after weight loss.

results Plasma ghrelin concentrations increased by 12% following weight loss (P < 0·01), and the increase in ghrelin levels was positively correlated with the extent of weight loss (r = 0·68, P < 0·05). Exposure to exogenous GH intravenously did not influence fasting ghrelin levels either before or after weight loss. Our data further suggest the existence of hyperghrelinaemia in a single subject with long‐standing obesity but no signs of GH excess.

conclusions This study provides evidence of a reversible suppression of ghrelin associated with obesity. The feasibility of measuring ghrelin in the circulation provides a new tool for the investigation of the complex hormonal regulation of appetite and energy balance.
The effects of age and renal and hepatic impairment on the pharmacokinetics of sildenafil
Authors: Muirhead Gary J. , Wilner Keith , Colburn Wayne , Haug‐Pihale Gertrude , Rouviex Bernhard
Published: March 2003

Aims  To investigate the effects of age and renal and hepatic impairment on the pharmacokinetics, tolerability and safety of sildenafil (single 50‐mg oral dose) and its major circulating N‐desmethyl metabolite, UK‐103,320.

Methods  Three open‐label, parallel‐group studies were conducted. The first study compared sildenafil pharmacokinetics, safety and toleration in 15 healthy young male subjects (mean age 30 years; range 19–45 years) to 15 healthy elderly male subjects (mean age 70 years; range 65–81 years). The second study included eight male volunteers with normal renal function and 16 male volunteers with varying degrees of renal impairment as assessed by measurement of creatinine clearance (CLcr). The third study included 12 male volunteers with normal hepatic function and 12 male volunteers with chronic stable hepatic cirrhosis (Child‐Pugh A and B). For all three studies, blood and urine samples were collected predose and at specified intervals up to 48 h postdose for assays of sildenafil and UK‐103,320, and measurements of protein binding.

Results  Significant differences in Cmax and AUC were observed between the young and the elderly subjects for both the parent drug and the metabolite. In the elderly, AUC values were approximately twice as high and Cmax values 60–70% higher than those for young men, while t1/2 values were approximately 1 h longer for sildenafil and 2 h longer for UK‐103,320. Due to a significantly smaller unbound fraction of drug in the elderly, free drug concentrations were only approximately 40% higher in the elderly group compared to the young group. In the renal impairment study, significant correlations with CLcr were demonstrated for sildenafil oral clearance (CL/F) and Cmax and UK‐103,320 Cmax and AUC. Pairwise comparisons between subjects with normal renal function and those with severe renal impairment (CLcr<30 ml min−1) supported these findings, showing significant increases in Cmax and AUC for both the parent drug and the metabolite in the severely impaired subjects. The hepatic impairment study demonstrated that the pharmacokinetics of sildenafil were altered in subjects with chronic stable cirrhosis, as shown by a 46% reduction in CL/F and a 47% increase in Cmax compared with subjects with normal hepatic function, suggesting a reduction in first‐pass metabolism as well as systemic clearance. The increase in systemic exposure for UK‐103,320 was approximately twice that seen for the parent drug. In all three studies, sildenafil was well tolerated, most adverse events were mild and no subjects discontinued treatment.

Conclusions  Sildenafil pharmacokinetics were affected by age and by renal and hepatic impairment, suggesting that a lower starting dose of 25 mg should be considered for patients with severely compromised renal or hepatic function.
Effects of supratherapeutic doses of ebastine and terfenadine on the QT interval
Authors: Gillen Michael S. , Miller Barry , Chaikin Philip , Morganroth Joel
Published: March 2003

Aims  The objective of this study was to compare the effects of high doses of ebastine with terfenadine and placebo on QTc.

Methods  Thirty‐two subjects were randomly assigned to four treatments (ebastine 60 mg day−1, ebastine 100 mg day−1, terfenadine 360 mg day−1, placebo) administered for 7 days. Serial ECGs were performed at baseline and day 7 of each period. QT interval was analysed using both Bazett (QTcB) and Fridericia (QTcF) corrections.

Results  Ebastine 60 mg (+ 3.7 ms) did not cause a statistically significant change in QTcB compared with placebo (+ 1.4 ms). The mean QTcB for ebastine 100 mg was increased by + 10.3 ms which was significantly greater than placebo but was significantly less (P < 0.05) than with terfenadine 360 mg (+ 18.0 ms). There were no statistically significant differences in QTcF between ebastine 60 mg (−3.2 ms) or ebastine 100 mg (1.5 ms) and placebo (−2.1 ms); although terfenadine caused a 14.1 ms increase which was significantly different from the other three treatments. The increase in QTcB with ebastine most likely resulted from overcorrection of the small drug‐induced increase in heart rate.

Conclusions  Ebastine at doses up to five times the recommended therapeutic dose did not cause clinically relevant changes in QTc interval.
Increased oral ganciclovir bioavailability in HIV‐infected patients with chronic diarrhoea and wasting syndrome—a population pharmacokinetic study
Authors: Mouly Stéphane , Aymard Guy , Tillement Jean‐Paul , Caulin Charles , Bergmann Jean‐Francois , Urien Saik
Published: March 2003

Aims  Despite a lack of data, the antiviral agent ganciclovir is not indicated in AIDS patients with diarrhoea because of its presumed poor oral bioavailability. To assess the effect of diarrhoea on ganciclovir intestinal absorption, we conducted a pharmacokinetic study in 42 HIV‐infected patients categorized into three groups: A, HIV stage A and B (n = 15); B, AIDS stage C (n = 13); C, AIDS with chronic diarrhoea and wasting syndrome (n = 14).

Methods  Each patient was evaluated for nutritional (body mass index, albumin, transferrin serum levels), inflammatory (haptoglobin, orosomucoid), immunological (CD4 count, plasma viral load) and intestinal (d‐xylose test, faecal fat and nitrogen output, intestinal permeability) status. Ganciclovir (1 g) was administered orally to fasted patients. Six blood samples were collected over 24 h. Serum was analysed for ganciclovir by h.p.l.c. Population pharmacokinetic analysis was performed using a nonlinear mixed effects modelling program, MP2.

Results  Mean intestinal permeability (lactulose/mannitol urinary ratio) was increased in group C (0.2) compared with group A (0.05) and B (0.1) patients. Drug concentration‐time profiles were best described by a two‐compartment model. Apparent oral clearance (CL/F) and central volume of distribution (V1/F) were influenced by clinical status (group). For groups A and B combined, final parameter estimates of CL/F and V1/F were 256 ± 98 l h−1 and 1320 ± 470 l, respectively. Final parameter estimates for group C were 118 ± 108 l h−1 and 652 ± 573 l for CL/F and V1/F, respectively. The 95% confidence intervals on differences between A and B combined and C were statistically significant ([ + 70, + 206] for CL/F, and [+ 314, + 1022] for V1/F). Compared with groups A and B, ganciclovir CL/F was significantly decreased in group C patients.

Conclusions  AIDS patients with diarrhoea and severe disease may benefit from ganciclovir therapy, but a dose adjustment may be required according to their digestive and immunological status.
Monitoring of Erwinia asparaginase therapy in childhood ALL in the Nordic countries
Authors: Albertsen Birgitte Klug , Schrøder Henrik , Jakobsen Preben , Müller Hans‐Joachim , Carlsen Niels T. , Schmiegelow Kjeld
Published: March 2003

Aims  Evaluation of l‐asparaginase therapy in the NOPHO‐92 ALL‐protocol (treatment protocol of acute lymphoblastic leukaemia of the Nordic Society of Paediatric Haematology and Oncology, initiated in 1992) after intravenous and intramuscular administration of Erwinia asparaginase during induction and re‐induction therapy.

Methods
 Forty children with newly diagnosed acute lymphoblastic leukaemia received Erwinia asparaginase (30 000 IU/m2 i.v. or i.m.) during induction therapy (every day for 10 days), and 19 children received Erwinia asparaginase (30 000 IU/m2 i.v. or i.m.) during re‐induction therapy (twice a week for 2 weeks). Within the treatment periods asparaginase trough activity (using a spectrophotometric assay) was determined on specific days. The goal of therapy is complete l‐asparagine depletion, which asparaginase activities above 100 IU l−1 have been shown to ensure. Therefore determination of l‐asparagine (using a h.p.l.c. method) was performed only in plasma samples with asparaginase activities below 100 IU l−1.

Results  During induction therapy 92.2% of the trough enzyme activities were above 500 IU l−1 for the i.v.‐treated patients, and 92.4% of the trough enzyme activities were above 500 IU l−1 for the i.m.‐treated patients. During re‐induction therapy 64.7% of the trough enzyme activities were below 100 IU l−1 in the i.v.‐treated group, and 73.3% of the trough enzyme activities were below 100 IU l−1 in the i.m.‐treated group. For trough enzyme activities below 100 IU l−1l‐asparagine depletion was complete in two thirds of the samples.

Conclusions  In the NOPHO‐92 ALL‐protocol l‐asparaginase treatment during induction therapy was unnecessarily intense, but during the re‐induction phase it appeared inadequate.
Population pharmacokinetics of amphotericin B in children with malignant diseases
Authors: Nath Christa E. , McLachlan Andrew J. , Shaw Peter J. , Gunning Robyn , Earl John W.
Published: March 2003

Aims  To construct a population pharmacokinetic model for the antifungal agent, amphotericin B (AmB), in children with malignant diseases.

Methods  A two compartment population pharmacokinetic model for AmB was developed using concentration‐time data from 57 children aged between 9 months and 16 years who had received 1 mg kg−1 day−1 doses in either dextrose (doseform=1) or lipid emulsion (doseform=2). P‐Pharm (version 1.5) was used to estimate the basic population parameters, to identify covariates with significant relationships with the pharmacokinetic parameters and to construct a Covariate model. The predictive performance of the Covariate model was assessed in an independent group of 26 children (the validation group).

Results  The Covariate model had population mean estimates for clearance (CL), volume of distribution into the central compartment (V) and the distributional rate constants (k12 and k21) of 0.88 l h−1, 9.97 l, 0.27 h−1 and 0.16 h−1, respectively, and the intersubject variability of these parameters was 19%, 49%, 55% and 48%, respectively. The following covariate relationships were identified: CL (l h−1) = 0.053 + 0.0456 weight0.75 (kg) + 0.242 doseform and V (l) = 7.11 + 0.107 weight (kg). Our Covariate model provided unbiased and precise predictions of AmB concentrations in the validation group of children: the mean prediction error was 0.0089 mg l−1 (95% confidence interval: −0.0075, 0.0252 mg l−1) and the root mean square prediction error was 0.1245 mg l−1 (95% confidence interval: 0.1131, 0.1349 mg l−1).

Conclusions  A valid population pharmacokinetic model for AmB has been developed and may now be used in conjunction with AmB toxicity and efficacy data to develop dosing guidelines for safe and effective AmB therapy in children with malignancy.
Clinical relevance of genetic polymorphisms in the human CYP2C subfamily
Authors: Goldstein Joyce A.
Published: March 2003

The human CYP2Cs are an important subfamily of P450 enzymes that metabolize approximately 20% of clinically used drugs. There are four members of the subfamily, CYP2C8, CYP2C9, CYP2C19, and CYP2C18. Of these CYP2C8, CYP2C9, and CYP2C19 are of clinical importance. The CYP2Cs also metabolize some endogenous compounds such as arachidonic acid. Each member of this subfamily has been found to be genetically polymorphic. The most well‐known of these polymorphisms is in CYP2C19. Poor metabolizers (PMs) of CYP2C19 represent approximately 3–5% of Caucasians, a similar percentage of African‐Americans and 12–100% of Asian groups. The polymorphism affects metabolism of the anticonvulsant agent mephenytoin, proton pump inhibitors such as omeprazole, the anxiolytic agent diazepam, certain antidepressants, and the antimalarial drug proguanil. Toxic effects can occur in PMs exposed to diazepam, and the efficacy of some proton pump inhibitors may be greater in PMs than EMs at low doses of these drugs. A number of mutant alleles exist that can be detected by genetic testing. CYP2C9 metabolizes a wide variety of drugs including the anticoagulant warfarin, antidiabetic agents such as tolbutamide, anticonvulsants such as phenytoin, and nonsteroidal anti‐inflammatory drugs. The incidence of functional polymorphisms is much lower, estimated to be 1/250 in Caucasians and lower in Asians. However, the clinical consequences of these rarer polymorphisms can be severe. Severe and life‐threatening bleeding episodes have been reported in CYP2C9 PMs exposed to warfarin. Phenytoin has been reported to cause severe toxicity in PMs. New polymorphisms have been discovered in CYP2C8, which metabolizes taxol (paclitaxel). Genetic testing is available for all of the known CYP2C variant alleles.
Limitation of the in vitro whole blood assay for predicting the COX selectivity of NSAIDs in clinical use
Authors: Blain Hubert , Boileau Christelle , Lapicque Françoise , Nédélec Emmanuelle , Lœuille Damien , Guillaume Cécile , Gaucher Alain , Jeandel Claude , Netter Patrick , Jouzeau Jean‐Yves
Published: March 2003

Aims  To assess if the inhibitory potency of nonsteroidal anti‐inflammatory drugs (NSAIDs) on cyclooxygenase (COX) isoenzymes, when given therapeutically in humans, can be predicted from their in vitro concentration‐response curves using the whole blood assay.

Methods  Twenty‐four healthy male volunteers aged 20–27 years were recruited. Inhibition of blood COX isoenzymes was determined in vitro before any drug intake and ex vivo after single and repeated intake of either 7.5 mg meloxicam once, 400 mg ibuprofen three times daily or 75 mg diclofenac SR once, taken in a randomized cross‐over design. Production of thromboxane B2 (TXB2) during clotting and of prostaglandin E2 (PGE2) during endotoxin exposure served as indicators of platelet COX‐1 and monocyte COX‐2 activity, respectively. Drugs were determined in plasma by h.p.l.c., with a chiral separation of ibuprofen and free fractions after equilibrium dialysis.

Results  Intra‐subject variation for COX‐1 and COX‐2 at baseline was at 26±18% and 18±13% respectively, and intersubject variation at 39% and 36%, respectively. The ratios of IC50s and, at best, of IC80s revealed diclofenac and meloxicam as selective COX‐2 inhibitors and ibuprofen as a preferential COX‐1 inhibitor in vitro. However, after oral intake, ibuprofen inhibited ex vivo COX‐2 by 80% whereas diclofenac inhibited COX‐1 by 70%. Meloxicam inhibited COX‐1 from 30 to 55% depending on the repetition of the dose and increase in plasma concentrations. Using in vitro dose–response curves, the in vivo inhibitory potency of diclofenac was estimated adequately from its circulating concentration ([−0.18, 0.21] for COX‐1 and [−0.13, −0.03] for COX‐2) but this was not the case for ibuprofen on COX‐2 ([−0.14, 0.27]) and meloxicam on COX‐1 ([0.31, 1.05]). The limited predictability of the system was not improved through considering the unbound fraction of the drugs or the variable chiral inversion of ibuprofen.

Conclusions  Assessment of COX‐2 selectivity based on in vitro studies and pharmacological modelling has a limited clinical relevance. There is a need to investigate COX selectivity at therapeutic plasma concentrations of NSAIDs using the ex vivo whole blood assay.
Prior flea beetle herbivory affects oviposition preference and larval performance of a potato beetle on their shared host plant
Authors: Wise Michael J. , Weinberg Abigail M.
Published: March 2003

Abstract 1. The herbaceous plant Solanum carolinense (L.) (Solanaceae) is host to a number of specialist insects, including the leaf‐feeding beetles Epitrix fuscula (Crotch) and Leptinotarsa juncta (Germar) (Coleoptera: Chrysomelidae). Potted individuals of S. carolinense were subjected to one of two treatments: exposure to herbivory by E. fuscula or exclusion of all herbivores. The effects of E. fuscula herbivory on larval performance and oviposition preference of L. juncta were investigated.

2. Although the masses of the L. juncta pupae did not differ between the two treatments, larvae feeding on damaged plants developed more slowly than those feeding on undamaged plants.

3. In both paired leaf choice trials and whole plant choice trials, larvae of L. juncta showed no preference for undamaged versus damaged hosts.

4. In a field transplant experiment, adult L. juncta females showed slight feeding preferences and strong oviposition preferences for undamaged plants versus plants that had been fed on by E. fuscula.

5. The results are discussed with reference to their implications for plant‐mediated competition among herbivores and constraints on the evolution of plant resistance.
Spatial patterns, temporal variability, and the role of multi‐nest colonies in a monogynous Spanish desert ant
Authors: Cerdá Xim , Dahbi Abdallah , Retana Javier
Published: March 2003

Abstract1. The colonies of the Spanish desert antCataglyphis ibericaare polydomous. This study describes the temporal and spatial patterns of the polydomy in this species at two different sites, and presents analyses of its role in reducing the attacks of the queen over sexual brood, and in allowing better habitat exploitation.

2. The spatial distribution of nests was clumped while colonies were distributed randomly. Mean nearest neighbour distance ranged from 3.4 to 7.0 m for nests and from 12.3 to 14.1 m for colonies. Distance of foragers searching for food varied among nests: mean values were between 6.1 and 12.6 m.

3. At both sites, the maximum number of nests per colony occurred in summer, during the maximum activity period of the species. Colonies regrouped at the end of this period but overwintered in several nests.

4. Nest renewal inC. ibericacolonies was high and showed great temporal variability: nests changed (open, close, re‐open) continuously through the activity season and/or among years. The lifetime of up to 55% of nests was only 1–3 months.

5. Polydomy inC. ibericamight decrease the interactions between the queen and the sexual brood. In all colonies excavated just before the mating period, the nest containing the queen did not contain any virgin female. Females were in the queenless nests of the colony.

6. The results also suggest that polydomousC. ibericacolonies may enhance habitat exploitation because foraging activity per colony increases with nest number. The relationship between total prey input and foraging efficiency and number of nests per colony attains a plateau or even decreases after a certain colony size (four to six nests). This value agrees with the observed mean number of nests per colony inC. iberica.
The efficacy and safety of sc Alniditan vs. sc Sumatriptan in the Acute Treatment of Migraine: A Randomized, Double-Blind, Placebo-Controlled Trial
Authors: Diener HC , Tfelt-Hansen P , de Beukelaar F , Ferrari MD , Olesen J , Dahlöf C , Mathew N ,   on behalf of the Study Group
Published: March 2003

This double-blind, placebo-controlled, parallel-group, multicentre, multinational, phase-III trial was designed to assess the efficacy and safety of a single subcutaneous injection of placebo, 2 doses of alniditan (1.4 mg and 1.8 mg) and 6 mg of sumatriptan in subjects with acute migraine. A total of 114 investigators from 13 different countries screened 2021 subjects. In total 924 patients were treated with placebo (157), alniditan 1.4 mg (309), alniditan 1.8 mg (141) and sumatriptan 6 mg (317). The lower number of subjects in the alniditan 1.8 mg group is due to the termination of this trial arm after the incidence of a serious adverse event and a subsequent protocol amendment. The number of subjects who were pain free at 2 h (primary endpoint) was: 22 (14.1%) with placebo, 174 (56.3%) with alniditan 1.4 mg, 87 (61.7%) with alnditan 1.8 mg and 209 (65.9%) with sumatriptan 6 mg. Alniditan 1.4 mg was significantly better ( P < 0.001) than placebo and sumatriptan was significantly better ( P = 0.015) than alniditan 1.4 mg. The number of responders (reduction of headache severity from moderate or severe headache before treatment to mild or absent at 2 h), was 59 (37.8%) on placebo, 250 (80.9%) on alniditan 1.4 mg, 120 (85.1%) on alniditan 1.8 mg, and 276 (87.1%) on sumatriptan. Response was significantly higher ( P < 0.001) with alniditan 1.4 mg than with placebo, and significantly lower ( P = 0.036) with alniditan 1.4 mg than with sumatriptan. Recurrence rates were: 22 (37.3%) with placebo, 87 (34.8%) with alniditan 1.4 mg, 35 (29.2%) with alniditan 1.8 mg and 108 (39.1%) with sumatriptan. Adverse events occurred in 577/924 (62.4%) subjects, i.e. in 62/157 (39.5%) with placebo, 214/309 (69.3%) with alniditan 1.4 mg, 91/141 (64.5%) with alniditan 1.8 mg and 210/317 (66.2%) with sumatriptan 6 mg. Sumatriptan was significantly better than alniditan 1.4 mg for pain free at 2 h. The difference, however, was small and clinically not important. For alniditan, a dose-dependent adverse event relationship was seen. The safety profile of alniditan 1.4 mg was similar to that of sumatriptan.
Detrital fission track thermochronology of Upper Cretaceous syn‐orogenic sediments in the South Carpathians (Romania): inferences on the tectonic evolution of a collisional hinterland
Authors: Willingshofer E. , Andriessen P. , Cloetingh S. , Neubauer F.
Published: March 2003

ABSTRACT The tectonic evolution of a collisional hinterland sourcing the Ha?eg Basin, a Late Cretaceous syn‐orogenic sedimentary basin in the South Carpathians (Romania), is revealed through fission track thermochronology of detrital apatite and zircon grains. This basin formed on the upper plate (Getic unit) in response to Late Cretaceous collision with the lower plate (Danubian unit), an allochtonous continental block of the Moesian Platform, upon closure of a narrow oceanic basin (Severin Basin). The fission track results suggest that Turonian to lower Maastrichtian sediments of the Ha?eg Basin have been dominantly derived from pre‐Late Cretaceous sources. The age components they contain relate to pre‐Cretaceous tectonothermal events such as the Variscan orogenic cycle, Jurassic rifting and Severin Basin formation, and to Early Cretaceous compressional tectonics. These results are compatible with the tectonic evolution of the upper plate that is identified as the primary source. From the onset of sedimentation (late Albian) until the early Campanian the Ha?eg Basin resembles a piggy‐back basin formed on the upper plate concomitant with underthrusting and internal stacking of the lower plate. In contrast, important tectonic subsidence during the late Campanian and early Maastrichtian reflects a shift to extensional tectonics causing the unroofing of the collision zone and the exhumation of lower plate rocks back to the surface. Our fission track data place important constraints on the timing of lower plate erosion that must have commenced during the late Maastrichtian, as documented by the completely reset Late Cretaceous age component within upper Maastrichtian sediments (Sînpetru Formation). Late Maastrichtian uplift of the basin and the formation of positive relief at the site of the collision zone is an expression of continuous convergence. The mismatch between the amount of denudation and the amount of sediments trapped in the Ha?eg Basin underlines the importance of concomitant extensional unroofing.
The effect of corona discharge on Der p 1
Authors: Goodman N. , Hughes J. F.
Published: March 2003

Background  Reduction of house dust mite allergens in the domestic environment can play an important part in reducing sensitization and in the amelioration of symptoms in atopic individuals. Chemical and physical methods have been tried with varied levels of success. The present paper presents a novel electrostatic way of destroying Der p 1, the major mite allergen.

Objective  To assess the efficacy of negative Trichel, negative continuous glow, positive pulse and positive continuous glow corona in destroying Der p 1. To determine whether ozone has any effect on the integrity of Der p 1 in the experimental conditions present.

Methods  A simple point‐to‐plane apparatus was used to irradiate samples of Der p 1 for periods of 1, 15, 30, 45, 60, 120, 180, 240 and 300 min. Controls were exposed to the atmosphere with no corona products present for the equivalent time. The effect of the corona by‐product ozone was investigated alone by exposing samples of Der p 1 to molecular ozone for 60 min. Der p 1 concentration was quantified by two‐site monoclonal antibody ELISA.

Results  High current negative glow resulted in a 67.37% reduction in Der p 1 concentration after 300 min compared with a 50.5% reduction from a low current Trichel regime. High current positive glow corona gave a reduction of 25.22% while a low current positive pulse corona caused a 13.72% reduction after 300 min. All these reductions were statistically significant (P < 0.05) compared with unexposed controls. Negative corona always gave greater percentage reductions in Der p 1 concentration for each time exposure investigated. The pattern of percentage reduction follows an exponential rise to maximum relationship in respect to time. Samples of Der p 1 were not affected by exposure to molecular ozone.

Conclusion  These data indicate corona products to be a powerful new method of destroying Der p 1 allergen that is not dependent on the presence of the oxidizing corona product ozone.
Prevalence and predictors of atopy among young Danish adults
Authors: Von Linstow M.‐L , Porsbjerg C , Ulrik C. S , Nepper‐Christensen S , Backer V
Published: March 2003

Background  The prevalence of atopic diseases is increasing in western countries, and environmental exposures in childhood may influence development of atopic sensitization.

Objective  To investigate the prevalence and predictors of atopy among young Danish adults.

Methods  Of 940 invited subjects, aged 19–29 years, complete data were obtained from 525 (56%) subjects. All completed a questionnaire concerning asthma, rhinitis, preschool nursery care, smoking habits, family size, education and employment. A skin prick test was performed, and pulmonary function was measured using standard techniques. Atopy was defined as a positive skin prick test.

Results  The frequency of atopy was 32% (males 43% vs. females 23%, P < 0.001). We found a positive association between atopy and atopic dermatitis (P < 0.05), rhinitis (P < 0.001), itching when eating nuts (P < 0.001) and current asthma (P < 0.001). There was an inverse relation between atopy and having furred pets in childhood (P < 0.05), passive smoking in childhood (P < 0.01) and current passive smoking (P < 0.05). An increasing number of siblings was inversely related to atopy to grass (P < 0.05); however, only an increasing number of older siblings seemed to protect from atopy to grass (P < 0.05). Subjects who had never attended a day‐care centre had significantly more atopy to grass (P < 0.05). No significant association was found between atopy and airway infections requiring hospitalization before the age of 5 years, or between atopy and bedroom sharing in childhood.

Conclusion  Atopy is common among young Danish adults, especially in males. Participants were less likely to be atopic, especially to grass allergen, if they came from large families, had kept furred pets as children, and had been exposed to tobacco smoke.
Modulation of the expression of the Cip/Kip family of cyclin‐dependent kinase inhibitors in foetal developing lungs of hamsters
Authors: Ikoma T. , Ito T. , Okudela K. , Hayashi H. , Yazawa T. , Kitamura H.
Published: March 2003

We examine the cell proliferation activity and expression of cyclin‐dependent kinase inhibitors of the Cip/Kip family, p21Cip1, p27Kip1 and p57Kip2, in foetal hamster lungs to determine the expression patterns of the cyclin‐dependent kinase inhibitors and to clarify the relationship between expression of the cyclin‐dependent kinase inhibitors and lung development. Foetal hamster lungs on gestational days 12.5–16 (the day of birth) and adult lungs were fixed in 4% paraformaldehyde. Frozen sections were immunostained for the cyclin‐dependent kinase inhibitors, and examined by immunostaining for Ki‐67 and bromodeoxyuridine to determine the proliferation activity of the foetal lungs. During the foetal period, cell proliferation activity, as analysed by Ki‐67 or bromodeoxyuridine labelling, decreased with development of the lung. In contrast to the gradual decrease of cell proliferation activity, cells with p27Kip1 immunoreactivity increased with development. On the other hand, p21Cip1‐positive cells were most prominent around gestational day 14.5, while after birth positive cells decreased markedly. A few p57Kip2‐positive cells were detected in the bronchiolar epithelium on gestational day 14.5. Western blotting analyses confirmed these immunostaining patterns. Thus, the levels of the cyclin‐dependent kinase inhibitors of the Cip/Kip family are modulated in the lungs during the foetal period, and each shows a unique expression pattern. The cyclin‐dependent kinase inhibitors may play roles not only in regulating cell proliferation activity but also in regulating other functions such as differentiation in the lung during the foetal period.