bluuebunny/crossref_metadata_2025_split huggingface dataset:
Potential of light trapping in microcrystalline silicon solar cells with textured substrates
Authors: Krč J. , Smole F. , Topič M. 
Published: October 2003

AbstractThe real and potential benefits of light trapping in microcrystalline silicon single‐junction solar cells are studied theoretically. Effects of a hypothetical high haze parameter of textured transparent conductive oxide on quantum efficiency and short‐circuit current of the solar cell are analysed by numerical simulation. The role of the angular distribution function of scattered light as a second important scattering parameter is shown. The potential thickness reductions of the intrinsic layer due to enhanced light trapping are demonstrated. Copyright © 2003 John Wiley & Sons, Ltd.
Quantifying epidemiologic risk factors using non‐parametric regression: model selection remains the greatest challenge
Authors: Rosenberg Philip S. , Katki Hormuzd , Swanson Christine A. , Brown Linda M. , Wacholder Sholom , Hoover Robert N. 
Published: October 2003

AbstractLogistic regression is widely used to estimate relative risks (odds ratios) from case–control studies, but when the study exposure is continuous, standard parametric models may not accurately characterize the exposure–response curve. Semi‐parametric generalized linear models provide a useful extension. In these models, the exposure of interest is modelled flexibly using a regression spline or a smoothing spline, while other variables are modelled using conventional methods. When coupled with a model‐selection procedure based on minimizing a cross‐validation score, this approach provides a non‐parametric, objective, and reproducible method to characterize the exposure–response curve by one or several models with a favourable bias–variance trade‐off. We applied this approach to case–control data to estimate the dose–response relationship between alcohol consumption and risk of oral cancer among African Americans. We did not find a uniquely ‘best’ model, but results using linear, cubic, and smoothing splines were consistent: there does not appear to be a risk‐free threshold for alcohol consumptionvis‐à‐visthe development of oral cancer. This finding was not apparent using a standard step‐function model. In our analysis, the cross‐validation curve had a global minimum and also a local minimum. In general, the phenomenon of multiple local minima makes it more difficult to interpret the results, and may present a computational roadblock to non‐parametric generalized additive models of multiple continuous exposures. Nonetheless, the semi‐parametric approach appears to be a practical advance. Published in 2003 by John Wiley & Sons, Ltd.
What is a ‘phycolichen’? Differences and changes in the meaning of an old lichenological term
Authors: Lange Otto L. , Wagenitz Gerhard 
Published: October 2003

AbstractThe term ‘phycolichens’ has recently been introduced as a synonym for ‘green algal lichens’ i.e. those having phycobionts as their primary autotrophic partner, which is analogous to the contracted term ‘cyanolichen’. However, a study of the history of the term ‘Phycolichenes’ leads us to suggest that this term should not be applied because of considerable ambiguities in past usage and the possibility of confusion. The term was first created by E. Fries in 1831, and was used later by Massalongo as a taxon for homoiomerous cyanobacterial lichens. With this, or similar meanings, it remained in use until the middle of the 20th Century. Diels (A. Engler's Syllabus der Pflanzenfamilien, Gebr. Borntr., Berlin, 1936) defined the same expression Phycolichenes as lichens with Phycomycetes as mycobiont, and this definition can still be found in recent literature. If a shortened term for green algal lichens is needed then we suggest ‘chlorolichens’ as a better counterpart to cyanolichens.
Interaction between fungal endophytes and environmental stressors influences plant resistance to insects
Authors: Bultman Thomas L. , Bell Gregory D. 
Published: October 2003

Neotyphodium coenophialum, an endophytic fungus that infects shoots of tall fescue (Festuca arundinacea), may protect its host from herbivory through production of alkaloids. Yet, the fungus can also modify plant resource allocation, regrowth dynamics, and drought tolerance, and these changes may also influence herbivores. We tested if N. coenophialum infection interacted with stress (drought or simulated herbivory) to modify plant resistance to insects. We assigned greenhouse plants to one of four treatments: 1) clipping at 3 cm above the soil surface, 2) drought stress during insect bioassays, 3) drought stress prior to insect bioassays, or 4) daily watering. Treatments were crossed with presence or absence of endophyte to give eight treatment combinations, and we assessed the performance of bird cherry‐oat aphid (Rhopalosiphum padi) and fall armyworm (Spodoptera frugiperda) feeding on plants in two separate experiments from each of the eight treatments. Aphids were placed into clip bags on leaf blades and allowed to reproduce parthenogenetically. Plant tissue was fed to third instar fall armyworm caterpillars until they molted into the fifth instar. Developmental time was recorded and larval growth was obtained gravimetrically. We also assessed total protein nitrogen (N) and loline alkaloids in plants.

Total protein N was unaffected by endophyte infection. In contrast, stress influenced total protein N, but its effect varied with endophyte infection. Uninfected plants that were clipped had higher total protein N; this trend was absent in infected plants. Plants in drought stress had lower N, but only if they were infected. Lolines were nearly absent from uninfected plants. In infected plants they tended to be higher in clipped plants. The effect of endophyte infection differed between the two insects: aphid reproduction was reduced by the endophyte, but endophyte infection enhanced caterpillar performance. Both insects were affected by interactions between the endophyte and stress. Aphids were negatively affected by drought stress, but only when feeding on uninfected plants, while caterpillars showed the opposite response, displaying lower performance on drought stressed plants only if they were infected. Aphids reproduced faster on regrowth tissue (following damage by clipping) of uninfected plants, but endophyte infection cancelled this effect. In contrast, performance of caterpillars was not influenced by an interaction between damage and infection. We conclude that N. coenophialum does not provide universal resistance to insects. Endophyte‐mediated resistance varies with insect species and will be a complex function of environmental stress, including drought and prior damage.
The Receptors and Role of Angiotensin II in Knee Joint Blood Flow Regulation and Role of Nitric Oxide in Modulation of Their Function
Authors: NAJAFIPOUR H. , KETABCHI F. 
Published: October 2003

ABSTRACTObjectives: Angiotensin‐converting enzyme (ACE) upregulation in the stroma cells of arthritis rheumatoid joints may produce a higher tissue concentration of angiotensin II (angII), which is a vasoconstrictor and mitogen factor that causes local hypoxia and synovial proliferation. No study in the literature has examined the role of angII in joint blood flow (JBF) regulation and the potential effect of ACE inhibitors on JBF.Methods: The study was performed on 20 Dutch white rabbits to examine the JBF response to angII, angII receptor subtypes, and the role of nitric oxide (NO) in angII effects in knee joint blood vessels. Drugs were administered locally through retrograde saphenous artery cannulation. Joint vascular resistance (JVR) was calculated by dividing the arterial blood pressure by the JBF.Results: AngII increased JVR dose dependently. The angII type 1 (AT1) receptor antagonist losartan did not change the basal JVR but completely blocked the effect of angII on JVR. Nω‐nitro‐L‐arginin methyl ester (L‐NAME) increased JVR by a mean (±SEM) of 25.8 ± 8.7% (p < 0.05) but did not affect the joint vessel response to angII and losartan.Conclusions: AngII receptors are from the AT1 subtype in normal joint blood vessels, but angII plays no significant role in JBF regulation. The basal release of NO plays a role in resting JBF regulation, but NO does not affect the AT1 receptor‐mediated vasoconstriction of joint blood vessels.
Abstention, alcohol use and risk of myocardial infarction in men and women taking account of social support and working conditions: the SHEEP case–control study
Authors: Romelsjö Anders , Branting Maria , Hallqvist Johan , Alfredsson Lars , Hammar Niklas , Leifman Anders , Ahlbom Anders 
Published: October 2003

ABSTRACTAims  Very few studies indicating that low–moderate alcohol consumption protects from myocardial infarction (MI) controlled for social support and working conditions, which could confound the findings. Therefore, a first aim was to study the risk of non‐fatal and total MI in relation to volume of alcohol consumption and measures of social support and working conditions. A second aim was to analyse the impact of the volume of earlier alcohol use in abstainers.Design  Data came from a case–control study, the Stockholm Heart Epidemiology Program (SHEEP), including first MI among Swedish citizens 45–70 years old.Setting  Stockholm County 1992–94.Participants  There were 1095 cases of MI in men and 471 in women (928 and 372 were non‐fatal), and 2339 living controls from the general population.Measurement  Information about alcohol use at different periods in life and job strain, social anchorage and life control besides pre‐existing health problems, smoking, physical activity, socio‐economic status and marital status was obtained by a questionnaire from the cases and the controls.Findings  In multivariate logistic regression analyses, the relative risk for MI (especially non‐fatal) was reduced among alcohol consumers. RR for non‐fatal MI was 0.52 (95% confidence intervals 0.32, 0.85) in men with a consumption of 50–69.9 g 100% ethanol/day and 0.21 (95% confidence interval 0.06, 0.77) in women with a consumption of 30 g or more per day (reference category 0.1–5 g 100% ethanol/day). Men who were abstainers during the previous 1–10 years and with an earlier average consumption of 5–30 g 100% ethanol/day had a significantly lower relative risk compared to such abstainers with an earlier higher consumption. Earlier consumption among abstainers may also have an impact on gender differences in MI. Analyses showed positive interaction between abstention and low life‐control in women, but only 4% of the female cases were due to this interaction. There were no other interactions between measures of alcohol use and social anchorage, life control and working situations.Conclusion  Alcohol use had a protective impact on MI, with little impact of job strain, social anchorage and life control, giving increased support for a protective impact of low‐moderate alcohol use. The level of previous alcohol consumption among male 1–10‐year‐long abstainers influenced the risk of MI.
Involvement of CYP2D6 but not CYP2C19 in nicergoline metabolism in humans
Authors: BÖTTIGER Y. , DOSTERT P. , STROLIN BENEDETTI M. , BANI M. , FIORENTINI F. , CASATI M. , POGGESTI I. , ALM C. , ALVAN G. , BERTILSSON L. 
Published: October 2003

1Nicergoline, an ergot derivative previously used as a vasodilator, has gained a new indication in treating the symptoms of senile dementia. 2Nicergoline is rapidly hydrolysed to an alcohol derivative, 1‐methyl‐10‐α‐methoxy‐9,10‐dihydrolysergol (MMDL), which is further N‐demethylated to form 10‐α‐methoxy‐9,10‐dihydrolysergol (MDL). A few individuals display aberrant metabolism of this drug, as shown by their diminished capacity to form the MDL metabolite. The aim of this study was to determine whether defective nicergoline metabolism is associated with the debrisoquine and/or the S‐mephenytoin hydroxylation polymorphisms. 3After a single, oral 30 mg dose of nicergoline, the plasma concentrations of its two metabolites were studied in 15 subjects, divided into three groups with respect to their debrisoquine and S‐mephenytoin hydroxylation phenotypes. 4The pharmacokinetic parameters of MMDL and MDL were similar in the ten subjects who were extensive metabolisers of debrisoquine (five of whom were poor metabolisers of S‐mephenytoin) (mean MMDL Cmax 59 nmol l−1 and AUC (0, th) 144 nmol l−1h, mean MDL Cmax 183 nmol l−1 and AUC 2627 nmol l−1h) but were markedly different from the five subjects who were poor metabolisers of debrisoquine (mean MMDL Cmax 356 nmol l−1 and AUC 10512 nmol l−1h, MDL concentrations below limit of quantitation). 5We conclude that the formation of MDL from MMDL in the metabolism of nicergoline is catalysed to a major extent by CYP2D6 and that the observed interindividual variation in the metabolic pattern of the drug is related to the debrisoquine hydroxylation polymorphism.
Characterization and validation of a pharmacokinetic model for controlled‐release oxycodone
Authors: MANDEMA JAAP W. , KAIKO ROBERT F. , OSHLACK BENJAMIN , REDER ROBERT F. , STANSKI DONALD R. 
Published: October 2003

1Oxycodone is a strong opioid agonist that is currently available in immediate‐release (IR) formulations for the treatment of moderate to severe pain. Recently, controlled‐release (CR) oxycodone tablets were developed to provide the benefits of twice‐a‐day dosing to patients treated with oxycodone. The purpose of this investigation was to develop and validate a pharmacokinetic model for CR oxycodone tablets in comparison with IR oxycodone solution. 2Twenty‐four normal male volunteers were enrolled in a single‐dose, randomized, analytically blinded, two‐way crossover study designed to compare the pharmacokinetics of two 10 mg CR oxycodone tablets with 20 mg IR oxycodone oral solution. Pharmacokinetic models describing the oxycodone plasma concentration vs time profiles of CR tablets and IR solution were derived using NONMEM version IV. The predictive performance of the models was assessed by comparison of predicted oxycodone plasma concentrations with actual oxycodone plasma concentrations observed in a separate group of 21 volunteers who received repeated doses of IR and CR oxycodone for 4 days. 3The unit impulse disposition function of oxycodone was best described by a one‐compartment model. Absorption rate of the IR solution was best described by a mono‐exponential model with a lag time, whereas absorption rate of the CR tablet was best described using a bi‐exponential model. The absorption profile of the CR tablets was characterized by a rapid absorption component (t1/2abs=37 min) accounting for 38% of the available dose and a slow absorption phase (t1/2abs=6.2 h) accounting for 62% of the available dose. Two 10 mg tablets of oral CR oxycodone hydrochloride were 102.7% bioavailable relative to 20 mg of IR oxycodone hydrochloride oral solution. The population model derived after administration of a single dose accurately predicted both the mean and range of oxycodone concentrations observed during 4 days of repeated dosing. The mean prediction error was 2.7% with a coefficient of variation of 54%. 4The absorption characteristics of CR oxycodone tablets should allow effective plasma concentrations of oxycodone to be reached quickly and for effective concentrations to be maintained for a longer period after dosing compared with the IR oral solution. The CR dosage form has pharmacokinetic characteristics that permit 12 hourly dosing.
A novel mutant variant of the CYP2D6 gene (CYP2D617) common in a black African population: association with diminished debrisoquine hydroxylase activity
Authors: MASIMIREMBWA COLLEN , PERSSON IRENE , BERTILSSON LEIF , HASLER JULIA , INGELMAN‐SUNDBERG MAGNUS 
Published: October 2003

1The debrisoquine hydroxylase (CYP2D6) is polymorphically distributed. Not only are there differences in the proportions of extensive metabolisers to poor metabolisers in various ethnic groups, but there are also pronounced variations in the metabolic capacity among those classified as extensive metabolisers. 2The mean debrisoquine metabolic ratio of Caucasian extensive metabolisers is lower than that for a number of African populations. In the present study, we have searched for novel CYP2D6 mutations to explain the diminished enzyme activity in African populations. 3Three Zimbabwean Shona subjects with EM phenotypes (metabolic ratios for debrisoquine of 0.4, 1.5 and 10.5 respectively) were selected and the open reading frame of the CYP2D6 gene of each was sequenced. 4The subject with metabolic ratio of 10.5 was found to be homozygous for an allele with a nucleotide exchange in exon 2, 1111C→T causing a 107Thr→Ile amino acid exchange in a conserved region of the enzyme. In addition, he was homozygous for the 2938C→T and 4268G→C mutations causing 296Arg→Ser and 486Ser→Thr amino acid substitution found in the CYP2D6*2 allele. 5Seventy‐six Zimbabwean Shona subjects were subsequently genotyped for the 1111C→T mutation and for the intron 1 gene conversion present in the CYP2D6*2 gene. The 1111C→T mutation was found at an allele frequency of 34% and was only present in alleles carrying the gene conversion in intron 1 indicative for the CYP2D6*2 gene. 6This allele (CYP2D6*17), containing the 1111C→T, 2938C→T and 4268G→C mutations, was found to be strongly associated with lower capacity for debrisoquine hydroxylation. We therefore postulate that the CYP2D6*17 allele might contribute to the molecular basis of the previously established diminished debrisoquine hydroxylase activity in African Bantu populations.
Pharmacokinetics of fluconazole in people with HIV infection: a population analysis
Authors: McLACHLAN A.J. , TETT S.E. 
Published: October 2003

1 The population pharmacokinetics of fluconazole have been investigated in 113 male subjects with HIV infection and AIDS. Plasma concentration–time data (between 1 and 17 observations per dose) were collected from individuals as part of a pharmacokinetic investigation (13 subjects) or during routine fluconazole therapy (100 subjects) for the treatment or prophylaxis of fungal infection. 2 A one‐compartment pharmacokinetic model was used to describe the disposition of fluconazole after oral and intravenous infusion doses. Population pharmacokinetic parameters were generated using the NONMEM and P‐PHARM computer programs. 3 The population estimates (calculated using NONMEM) of fluconazole clearance and volume of distribution were 0.78 l h−1 and 47.6 l, respectively. The intersubject variability for these parameters was 41% and 8%, respectively. The model‐dependent estimate of the extent of absorption was 0.99 with an intersubject variability of 6%. Mean population estimates generated by NONMEM and P‐PHARM were in close agreement. 4 Examination of the relationship between patient covariates and pharmacokinetic parameters indicated that intersubject variability in fluconazole clearance could in part be explained by the severity of disease (as indicated by CD4+T‐lymphocyte count) and renal function (indicated by estimated creatinine clearance). Other pharmacokinetic parameters were unaffected by these covariates. 5 Fluconazole clearance (estimated using NONMEM) in subjects with a CD4+T‐lymphocyte count less than and greater than 200 cells mm3 was 0.73 l h−1 (95% CI ; 0.64–0.82 l h−1) and 0.99 l h−1 (95% CI ; 0.86–1.12 l h−1), respectively. The regression model for fluconazole clearance that accounted for changes in renal function and disease severity was CL (l h−1)=0.25 (33%)+0.0057 (32%)×CLcr (in ml min−1)+0.00068 (10%)×CD4 cell count (in cells mm−3) where intersubject variability (expressed as %CV) is shown in brackets. 6 Based on pharmacokinetic considerations a reduction in the dose of fluconazole would appear to be warranted in people with HIV infection who are seriously ill or who have compromised renal function. However, the emergence of resistance to fluconazole must also be considered when thinking of dosage adjustments.
Pharmacodynamics of oxypurinol after administration of allopurinol to healthy subjects
Authors: GRAHAM S. , DAY R. O. , WONG H. , McLACHLAN A. J. , BERGENDAL L. , MINERS J. O. , BIRKETT D. J. 
Published: October 2003

1 Eight healthy subjects received 50, 100, 300, 600 and 900 mg allopurinol daily for 1 week each, in random order with 1 week separating each treatment period. The pre‐dose plasma concentration of oxypurinol, the extent of inhibition of xanthine oxidase, plasma urate concentration and urine urate excretion rate were assessed on the last 2 days of each treatment week. 2 The ratio of 1‐methyluric acid (1MU) over 1‐methylxanthine (1MX) in the urine, following a dose of 50 mg 1MX infused intravenously over 20 min, was used to measure the inhibition of xanthine oxidase. 3 The steady‐state plasma concentration of oxypurinol increased linearly with increasing dose of allopurinol between 50 mg to 600 mg day−1, with a weak indication of saturation at the higher 900 mg day−1 dose rate. 4 The relationships between plasma oxypurinol concentration and xanthine oxidase inhibition (1MU/1MX ratio), plasma urate concentration and urine urate excretion rate were fitted to an inhibition sigmoid Emax model and the C50 values for oxypurinol were 26.38±4.87, (mean±s.d.) 36.58±8.36 and 24.61±9.08 μm, respectively. 5 1MU/1MX ratio appeared to be a reliable index of xanthine oxidase activity in vivo as the C50 for oxypurinol observed for 1MU/1MX ratio, plasma urate concentration and urine urate excretion rate were similar. 6 The concentration of oxypurinol required for inhibition of xanthine oxidase, as indicated by C50, was lower than those often observed in clinical practice.
Fluconazole, but not terbinafine, enhances the effects of triazolam by inhibiting its metabolism
Authors: VARHE ANU , OLKKOLA KLAUS T. , NEUVONEN PERTTI J 
Published: October 2003

1 The interaction between triazolam and two antifungal agents, fluconazole and terbinafine, was investigated in a double‐blind, randomized crossover study of three phases. 2 Twelve healthy young volunteers received 100 mg fluconazole, 250 mg terbinafine or placebo orally once a day for 4 days. On day 4 they took a single 0.25 mg dose of triazolam. Plasma samples were collected and pharmacodynamic effects were measured up to 17 h after the intake of triazolam. 3 Fluconazole increased the area under the triazolam concentration time‐curve more than twofold (P<0.001) and prolonged the elimination half‐life of triazolam nearly twofold (P<0.001). The peak concentration of triazolam was also increased significantly (P<0.05) by fluconazole. 4 During the fluconazole phase pharmacodynamic effects of triazolam (e.g. digit symbol substitution test, body sway and drowsiness) were enhanced significantly (P<0.05) when compared with the placebo phase. 5 Terbinafine did not change significantly the pharmacokinetics or pharmacodynamics of triazolam. 6 Care should be taken when triazolam is prescribed to patients using fluconazole. Although the interaction is not as strong as that of triazolam with ketoconazole or itraconazole, it is clinically significant. Triazolam and probably other drugs metabolized by CYP3A4 can be used in normal doses with terbinafine.