bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationship Between Hypercholesterolemia, Lipid‐Lowering Therapy and Coronary Flow Velocity Reserve Evaluated by Stress Transesophageal Echocardiography in Patients with a Negative Coronary Angiogram
Authors: Nemes Attila , Neu Klára , Forster Tamás , Gruber Noémi , Csanády Miklós
Published: October 2004

Summary: The coronary flow velocity reserve (CFR) depends not only on vascular, extravascular, and rheological factors, but also on metabolic factors, such as the cholesterol level. The aim of the present study was to examine the relationship between hypercholesterolemia, the application or not of 6 months lipid‐lowering therapy, and the CFR evaluated by pharmacological stress transesophageal echocardiography (PSTEE) in patients without major coronary artery disease. Patients and Methods: Sixty‐nine patients with a negative coronary angiogram were enrolled in the study. Thirty‐two of these patients received lipid‐lowering therapy, while 37 did not. The CFR was measured by means of dipyridamole PSTEE in all cases, and was calculated as the ratio of posthyperemic to basal peak diastolic flow velocities. Results: Of the 32 patients who received lipid‐lowering medication, the cholesterol level was normal in 16 cases (CFR 2.47 ± 0.88), while it remained increased in 16 patients (CFR 2.18 ± 0.67) at the time of the examination. The 7 patients who did not participate in lipid‐lowering therapy and who exhibited an increased cholesterol level were also examined (CFR 2.03 ± 0.88). In 30 patients with normal cholesterol level, who did not receive any lipid‐lowering medication, the CFR was significantly increased compared to cases with an increased level (CFR 2.65 ± 0.79). Conclusion: It may be stated that in the patients who did not receive lipid‐lowering medication and who displayed normocholesterolemia, the CFR evaluated by means of PSTEE was significantly higher than in the patients who had an increased cholesterol level. (ECHOCARDIOGRAPHY, Volume 21, January 2004)
Unusual Presentation of Papillary Fibroelastoma: Utility of Serial Transesophageal Echocardiograms
Authors: Vora Tushar R. , Lażos Thomas J. , López‐Candales Angel
Published: October 2004

Papillary fibroelastomas are uncommon benign tumors usually involving heart valves that may be potential sources of emboli. Transesophageal echocardiography has greatly enhanced the ability to make the diagnosis of these surgically treatable tumors in a timely fashion. We describe an unusual presentation of a 62‐year‐old man with suspected bacterial endocarditis, in whom initial transesophageal echocardiogram suggested the presence of pacemaker lead infection but a repeat study after extraction of the pacemaker lead revealed a large pedunculated mass arising from the superior vena cava. The mass was surgically removed and histopathology revealed papillary fibroelastoma. This case is unusual with respect to the size and site of origin of the papillary fibroelastoma as well as its echocardiographic presentation mimicking vegetations on a pacemaker wire. (ECHOCARDIOGRAPHY, Volume 21, January 2004)
Adolescent alcohol misuse: methodological issues for enhancing treatment research
Authors: Colby Suzanne M. , Lee Christina S. , Lewis‐Esquerre Johanna , Esposito‐Smythers Christianne , Monti Peter M.
Published: October 2004

Aims The objective of this article is to present an overview of the current state of the field of adolescent alcohol treatment research and to discuss several priorities for future research directions.

Method The authors identified trends in adolescent alcohol treatment research from multiple sources, including searches of the National Institutes of Health grantee listings, proceedings from annual meetings of the Research Society on Alcoholism and relevant English‐language journal articles available in MEDLINE and PSYCHLIT databases over the past decade.

Research recommendations This field must build on its major strength, which has been its success in appreciating the unique developmental characteristics of adolescence and meaningfully incorporating them into adolescent alcohol treatment approaches. Priorities for future research include: empirically investigating the potential value of harm reduction approaches for promoting public health and reducing total harm for adolescents; developing efficacious interventions across a wide range of intensities and settings; increasing the reach and relevance of randomized treatment efficacy trials and their products, with a particular focus on enhancing the recruitment and retention of diverse treatment samples; increasing a focus on key individual difference variables such as co‐occurring diagnoses, that may serve as the basis for treatment tailoring; and exploration of the potential benefits of transdisciplinary research.
Motivational enhancement and other brief interventions for adolescent substance abuse: foundations, applications and evaluations
Authors: Tevyaw Tracy O’Leary , Monti Peter M.
Published: October 2004

Aims  To present a comprehensive review of the use of motivational enhancement and other brief interventions for substance use in adolescents.

Methods  In this paper, we review the major theoretical foundations and influences of brief interventions (including motivational interviewing), consider developmental issues in its application for adolescents, discuss methodological issues in the design and implementation of brief interventions, including the assessment of treatment fidelity, evaluate and interpret the latest findings on brief interventions for adolescents and young people and discuss the issue of translating and exporting effective research into practice.

Findings  Results from recent clinical trials using motivational interventions indicate that these approaches result in decreases in substance‐related negative consequences and problems, decrements in substance use and increased treatment engagement, with results particularly strong for those with heavier substance use patterns and/or less motivation to change.

Conclusion  While results are promising, more research is needed to examine the essential elements of motivational interventions, for whom they work best, and their impact on developmental transitions during adolescence.
Family‐based therapies for adolescent alcohol and drug use: research contributions and future research needs
Authors: Liddle Howard A.
Published: October 2004

Objective  To characterize the developmental status of the family‐based adolescent alcohol and drug treatment specialty by identifying and discussing research and clinical advances.

Method  Selective and interpretative literature review and analysis.

Study selection  Controlled trials and mechanisms of change studies of family‐based treatments for adolescent alcohol and drug misuse.

Results  Clinical innovations of family‐based treatments include development of detailed therapy, training/supervision, and adherence manuals. Different family‐based treatments have been tested with success in controlled trials and process studies. Different versions of the same approach might vary on parameters such as treatment dose, setting, and client characteristics. Research advances include findings that engagement and retention rates for family‐based treatments are superior to standard treatment engagement/retention methods. Also, in clinical trials in which they are compared with alternative interventions, in the majority of studies, family‐based treatments produce superior and stable outcomes with significant decreases on target symptoms of alcohol and drug use, and related problems such as delinquency, school and family problems, and affiliation with substance abusing peers. Mechanisms of change studies support the theory basis of family‐based treatments. For instance, improvements in family interaction patterns coincide with decreases in core target alcohol and drug misuse symptoms.

Conclusions  Once in the shadows of the adult substance abuse field, the adolescent substance abuse specialty has become a unique, clinically creative, and empirically‐based area. Research and clinical advances of family‐based treatments have implications for non‐family‐based interventions in the adolescent substance misuse treatment specialty.
Cross‐validation of the alcohol and cannabis use measures in the Global Appraisal of Individual Needs (GAIN) and Timeline Followback (TLFB; Form 90) among adolescents in substance abuse treatment
Authors: Dennis Michael L. , Funk Rodney , Godley Susan Harrington , Godley Mark D. , Waldron Holly
Published: October 2004

Aims  To examine the comparability, reliability and predictive validity of two instruments used to assess alcohol use and dependence: the Global Appraisal of Individual Needs (GAIN) and the Form 90 Timeline Followback (TLFB) method.

Design, setting and participants  Adolescents (n = 101) admitted to a residential treatment program in the United States were interviewed at intake with the GAIN, and again within a week with a variation of TLFB, called Form 90. Alcohol and cannabis measures were compared and used to predict the number of past‐month substance abuse and dependence symptoms.

Measurement  Self‐report measures of days of alcohol and cannabis use in the 90 days prior to intake, peak number of drinks/joints used, peak blood alcohol content (BAC) and alcohol and cannabis abuse and dependence symptom counts.

Findings  Results revealed that the measures had: (a) excellent comparability (r = 0.7–0.8) across the two instruments; (b) deteriorating reliability after reported peak BAC levels exceeded 0.50 and peak joints exceeding 19; and (c) similar and strong relationships between use measures and the number of abuse/dependence symptoms across measures and instruments.

Conclusions  In a sample of 101 adolescents who were admitted to residential treatment for alcohol or drug dependence, the corresponding measures from the two instruments produced comparable results. If the cross‐validation of these two measures generalizes to adolescents treated in out‐patient settings and other adolescent treatment populations, the GAIN and Form 90 may provide useful core alcohol measures for meta‐analyses.
Culturally sensitive substance abuse intervention for Hispanic and African American adolescents: empirical examples from the Alcohol Treatment Targeting Adolescents in Need (ATTAIN) Project
Authors: Gil Andrés G. , Wagner Eric F. , Tubman Jonathan G.
Published: October 2004

Aims  This study presents preliminary analyses examining the effects of an alcohol and other drug use (AOD) intervention with minority juvenile offenders. Furthermore, the study investigates the impact of cultural factors on baseline AOD use among Hispanic and African American youth, as well as on treatment outcome.

Design, setting and participants  Participants were 213 juvenile offenders referred for treatment (mean age = 15.7 years), 97 of whom have completed treatment to date. The intervention was carried out in clinics placed within the neighborhoods in which the participants resided.

Intervention  Alcohol Treatment Targeting Adolescents in Need (ATTAIN) is a controlled clinical trial evaluating the effectiveness of a brief motivational, cognitive behavioral intervention, guided self‐change (GSC). Participants are assigned randomly to the individual format of guided self‐change (I‐GSC), the family involved format of guided self‐Change (F‐GSC), choice of one of these two, or a waiting list control condition. Only participants involved in active intervention are included in the present report.

Measurements  Data were collected via structured face‐to‐face interviews. Alcohol and marijuana use measures were collected using the Time‐line Follow‐back interview (TLFB).

Findings  There were significant reductions in alcohol and marijuana use for all ethnic groups from baseline to post‐intervention. Cultural factors (discrimination, acculturation, ethnic pride and cultural mistrust) were associated with pre‐intervention levels of alcohol and marijuana use. Among Hispanics, pre‐intervention level of substance use were higher among foreign‐born than US‐born youth. Analyses conducted with the US‐born Hispanic group showed that ethnic orientation and ethnic pride were associated positively with greater reductions in alcohol use.

Conclusions  The intervention provided through ATTAIN appears to be effective with a multi‐ethnic population of juvenile delinquents. Cultural factors, such as ethnic orientation and ethnic mistrust, appear to constitute amenability to treatment factors, with US‐born Hispanic youth lower in acculturation responding better to the intervention.
Treasure!
Authors: Middleton Andrew ,   the Science Group
Published: October 2004

The word ‘treasure’ conjures an image of objects of silver and gold, perhaps encrusted with gemstones, and some treasures dug from the ground certainly match this image (Fig. 1). However, a theme that ran through the recent exhibition of Treasure at the British Museum was that the archaeological value of treasure does not depend only on its content of precious metals or gems. Many items recovered from archaeological sites are made from or include natural rocks, minerals and gemstones, so that geological and mineralogical techniques and interpretative approaches often make an essential contribution to their study. This article explores the role of scientific examination in realizing the full archaeological value of treasure.

Group of items from a Roman hoard, found at Thetford. These objects are not in Treasure but may be seen in Gallery 49 of the British Museum.

image
Tenerife – the big pyramid
Authors: Greensmith Trevor
Published: October 2004

There is nothing like a good controversy in geology, when vehemently held conflicting opinions set the adrenaline running. The debate over hot spots or mantle plumes is developing in this way; as such it is pertinent to look at the Canary Islands archipelago where hot spot ideas have been in place for some time.
The impact of intrinsic motivation on e‐learning in authentic computer tasks
Authors: Martens RobL. , Gulikers Judith , Bastiaens Theo
Published: October 2004

Abstract Students with high intrinsic motivation often outperform students with low intrinsic motivation. However, little is known about the processes that lead to these differences. In education based on simulations or authentic electronic learning environments, this lack of insight is even more clear. The present study investigated what students actually did in an electronic learning environment that was designed as a game‐like realistic simulation in which students had to play the role of a junior consultant. The results show that students with high intrinsic motivation did not do more, rather they tended to do different things. Analysis of log files showed that the increased curiosity that students with high intrinsic motivation have, resulted in proportionally more explorative study behaviour. However, the learning outcomes of students with high intrinsic motivation were not better.
Cueing for transfer in multimedia programmes: process worksheets vs. worked‐out examples
Authors: Hummel Hans G. K. , Paas Fred , Koper E. J. R.
Published: October 2004

Abstract We investigate the effects of cueing, in a multimedia programme for the individualized training of the ‘whole task’ to prepare a plea, on the learning outcomes of 43 sophomore law students. The cueing formats of worked‐out examples (WOEs), process worksheets (PWs), and both WOE and PW are compared to a no‐cueing control condition. Our hypotheses that WOE enhance near transfer, by stimulating imitation processes to similar tasks, and that PW foster far transfer, by stimulating mindful abstraction processes to different tasks were partly confirmed by learning outcomes on the training task and two transfer tasks.
Prevalence of macrovascular disease amongst type 2 diabetic patients detected by targeted screening and patients newly diagnosed in general practice: the Hoorn Screening Study
Authors: Spijkerman A. M. W. , Henry R. M. A. , Dekker J. M. , Nijpels G. , Kostense P. J. , Kors J. A. , Ruwaard D. , Stehouwer C. D. A. , Bouter L. M. , Heine R. J.
Published: October 2004

Objectives.  Screening for type 2 diabetes has been recommended and targeted screening might be an efficient way to screen. The aim was to investigate whether diabetic patients identified by a targeted screening procedure differ from newly diagnosed diabetic patients in general practice with regard to the prevalence of macrovascular complications.

Design.  Cross‐sectional population‐based study.

Setting.  Population study, primary care.

Subjects.  Diabetic patients identified by a population‐based targeted screening procedure (SDM patients), consisting of a screening questionnaire and a fasting capillary glucose measurement followed by diagnostic testing, were compared with newly diagnosed diabetic patients in general practice (GPDM patients). Ischaemic heart disease and prior myocardial infarction were assessed by ECG recording. Peripheral arterial disease was assessed by the ankle‐arm index. Intima‐media thickness of the right common carotid artery was measured with ultrasound.

Results.  A total of 195 SDM patients and 60 GPDM patients participated in the medical examination. The prevalence of MI was 13.3% (95% CI 9.3–18.8%) and 3.4% (1.0–11.7%) in SDM patients and GPDM patients respectively. The prevalence of ischaemic heart disease was 39.5% (95% CI 32.9–46.5%) in SDM patients and 24.1% (15.0–36.5%) in GPDM patients. The prevalence of peripheral arterial disease was similar in both groups: 10.6% (95% CI 6.9–15.9%) and 10.2% (4.7–20.5%) respectively. Mean intima‐media thickness was 0.85 mm (±0.17) in SDM patients and 0.90 mm (±0.20) in GPDM patients. The difference in intima‐media thickness was not statistically significant.

Conclusions.  Targeted screening identified patients with a prevalence of macrovascular complications similar to that of patients detected in general practice, but with a lower degree of hyperglycaemia.
Autosomal recessive hypercholesterolaemia: normalization of plasma LDL cholesterol by ezetimibe in combination with statin treatment
Authors: Lind S. , Olsson A. G. , Eriksson M. , Rudling M. , Eggertsen G. , Angelin B.
Published: October 2004

Background.  Severe hereditary hypercholesterolaemia is most frequently due to familial hypercholesterolaemia (FH), caused by mutations in the LDL receptor (LDLR) gene. However, a phenotype very similar to FH may also be caused by defects in other genes like the genes for apolipoprotein (apo) B‐100 or autosomal recessive hypercholesterolaemia (ARH).

Subject.  An 8‐year‐old male of Lebanese origin was diagnosed with severe hypercholesterolaemia and extensive cutaneous and tendon xanthomas. Plasma LDL cholesterol before treatment was 17 mmol L−1, whilst parents and both siblings had normal levels.

Diagnosis.  Degradation of 125I‐labelled LDL in blood lymphocytes was reduced, but not abolished. Sequencing analysis of the LDLR and apoB‐100 genes were negative, whilst a splice acceptor mutation in intron 1 (IVS 1 –1G>C) was detected in the ARH gene. The patient was homozygous for the mutation, whilst the parents were heterozygous. These findings were in agreement with a diagnosis of ARH.

Treatment and clinical course.  Monthly LDL apheresis and atorvastatin 120 mg daily reduced LDL cholesterol preapheresis level to 4.8 mmol L−1. When ezetimibe was given 10 mg day−1 in combination with rosuvastatin 80 mg day−1, LDL cholesterol was further lowered to 1.6 mmol L−1, which made apheresis unnecessary. Cutaneous and tendon xanthomas disappeared completely and the intima‐media thickness of the common carotid arteries decreased. At age 23 he developed a small myocardial infarction.

Conclusion.  ARH should be considered in cases of severe hypercholesterolaemia with a pattern of recessive inheritance. Combination therapy with high‐dose statin and ezetimibe seems to be the treatment of choice in ARH and may reduce or eliminate the need for LDL apheresis treatment.
Oxidized low‐density lipoprotein in plasma is a prognostic marker of subclinical atherosclerosis development in clinically healthy men
Authors: Wallenfeldt K. , Fagerberg B. , Wikstrand J. , Hulthe J.
Published: October 2004

Objective.  To investigate the association between plasma oxidized low‐density lipoprotein (OxLDL) and the progress of clinically silent atherosclerosis, as measured by ultrasound in the carotid arteries.

Design.  Prospective, observational study with more than 3 years of follow‐up.

Setting.  One‐centre study at university hospital.

Material and methods.  The subjects (n = 326) were obtained by stratified sampling from a population sample of men who were 58 years old at baseline. Carotid artery intima‐media thickness (IMT) was measured bilaterally by high‐resolution B‐mode ultrasound at baseline and after follow‐up. Plasma OxLDL cholesterol concentrations and conventional cardiovascular risk factors were measured at study entry. Automated measurements of IMT were performed. Plaque occurrence and size were assessed (plaque status). Plasma OxLDL at entry was measured by a specific monoclonal antibody, mAb‐4E6.

Results.  OxLDL at entry, but not LDL cholesterol, was associated with the number and size of plaques at follow‐up (P = 0.008), also after adjustment for plaque status at entry (P = 0.033). The plasma OxLDL concentration at entry was associated with change in carotid artery IMT (r = 0.17; P = 0.002) and in a stepwise multiple regression analysis this association remained after adjustment for other cardiovascular risk factors (P = 0.005).

Conclusions.  These results provide new information, supporting the concept that circulating OxLDL was associated with the silent phase of atherosclerosis progression in clinically healthy men independently of conventional risk factors.
Inflammatory markers and heart rate variability in women with coronary heart disease
Authors: Janszky I. , Ericson M. , Lekander M. , Blom M. , Buhlin K. , Georgiades A. , Ahnve S.
Published: October 2004

Purpose.  Both heart rate variability (HRV) and inflammatory markers are carrying prognostic information in coronary heart disease (CHD), however, we know of no studies examining their relation in CHD. The aim of this study, therefore, was to assess the association between HRV and inflammatory activity, as reflected by the levels of interleukin‐6 (IL‐6), IL‐1 receptor antagonist (IL‐1ra) and C‐reactive protein (CRP).

Subjects and methods.  Consecutive women patients who survived hospitalization for acute myocardial infarction, and/or underwent a percutaneous transluminal coronary angioplasty or a coronary artery bypass grafting were included and evaluated in a stable condition 1 year after the index events. An ambulatory 24‐h ECG was recorded during normal activities. SDNN index (mean of the standard deviations of all normal to normal intervals for all 5‐min segments of the entire recording) and the following frequency domain parameters were assessed: total power, high frequency (HF) power, low frequency (LF) power and very low frequency (VLF) power. Levels of high‐sensitivity CRP were measured by nephelometry, IL‐6 and IL‐1ra concentrations were determined by enzyme immunoassay.

Results.  Levels of IL‐6 showed an inverse relation with HRV measures even after controlling for potential confounding factors. The P‐values were 0.02, 0.04, 0.01, 0.03, 0.18 for the multivariate association with SDDN index, total power, VLF power, LF power and HF power respectively. In contrast, the inverse relationship between HRV measures and CRP or IL‐1ra levels were weak and nonsignificant. Correlation coefficients for the relationship between IL‐6 and HRV measures were both uni‐ and multivariately higher than for the relationship between HRV measures and any other factors evaluated in this study.

Conclusion.  Concentration of IL‐6 showed a negative, independent association with HRV in women with CHD. Thus, increased inflammatory activity, as reflected by IL‐6 levels, may represent a new auxiliary mechanism linking decreased HRV to poor prognosis in CHD.
Diagnosing heart failure in aortic valve stenosis
Authors: Kupari M. , Turto H. , Lommi J.
Published: October 2004

Objective.  In aortic valve stenosis (AS), heart failure (HF) omens a high risk of death and is an indication for prompt valve replacement. We studied whether its detection can be facilitated by measuring plasma N‐terminal B‐type natriuretic peptide (Nt‐BNP) or by estimating pulmonary capillary wedge pressure (PCWP) using echocardiography.

Design and setting.  A cross‐sectional cohort study in a university hospital.

Subjects and methods.  We studied 137 consecutive adult patients referred to our unit for invasive evaluation of isolated AS. All patients underwent cardiac catheterization, measurement of plasma Nt‐BNP and estimation of PCWP by Doppler echocardiography of transmitral and pulmonary venous flow velocities. The final diagnosis of HF was based on the combined criteria of dyspnoea on ordinary effort and PCWP >14 mmHg at cardiac catheterization. The performance of Nt‐BNP and the PCWP estimate in the detection of HF were studied using receiver operating characteristic (ROC) analysis.

Results.  Totally 42 patients had HF. A cardiologist's clinical diagnosis of HF had high specificity (94%) but poor sensitivity (66%). With an optimized cut‐off point, plasma Nt‐BNP had moderate sensitivity (77%) and specificity (79%) for HF; the ROC area was 0.83. The echocardiographic PCWP estimate classified 90% of patients correctly as having normal or truly elevated (>14 mmHg) PCWP. Its sensitivity and specificity for the diagnosis of HF were 80 and 95% respectively; the ROC area was 0.88. With a cut‐off point of 12 mmHg, the sensitivity of the PCWP estimate was 85% and specificity, 88%.

Conclusion.  The recognition of HF in patients with AS can be improved by estimating PCWP using Doppler echocardiography of transmitral and pulmonary venous flow velocities.
An analysis of plant–aphid interactions by different microarray hybridization strategies
Authors: VOELCKEL C. , WEISSER W. W. , BALDWIN I. T.
Published: October 2004

Aphids have long been considered ‘stealthy’ herbivores that subvert a plant's induced defenses and manipulate its source‐sink signaling, but these hypotheses are largely untested at a transcriptional level. We analysed gene expression in native tobacco plants (Nicotiana attenuata) infested with Myzus nicotianae aphids, without resorting to the use of clip‐cages, with a cDNA microarray containing 240 defense‐related N. attenuata genes. Using a hybridization scheme (‘ratio analysis’ and ‘state analysis’) broadly applicable in two‐factor analyses, we examined how the aphids influenced source–sink relationships and determined if their feeding preference, apart from benefiting from the sink strength of young leaves, was associated with the expression of known plant defense genes. In contrast to the responses elicited by attack from tissue‐feeding lepidopteran larvae and mesophyll‐sucking insects, attack from phloem‐feeding aphids elicited only weak responses. Similar to other herbivores, M. nicotianae feeding increased the expression of trypsin protease inhibitors (TPI), lipoxygenase, and xyloglucan‐endotransglycosylase genes, and decreased small RUBISCO subunit and ubiquitin carrier protein transcripts. Aphid‐specific changes included the up‐regulation of glutamate synthase and the down‐regulation of a germin‐like protein. Aphids preferentially settled on younger leaves, which expressed more hydroperoxide lyase and TPI than did older leaves, suggesting that these genes, which mediate the synthesis of compounds reported to be toxic for aphids in other plant systems, are either not under transcriptional control or not important in this system. By identifying aphid‐responsive genes, we have made a first step in identifying the ‘genes that matter’ in plant–aphid interactions.
Estimating pairwise relatedness from dominant genetic markers
Authors: WANG J.
Published: October 2004

Knowledge of the genetic relatedness between a pair of individuals is important in many research areas of quantitative genetics, conservation genetics, evolution and ecology. Many estimators have been developed to estimate such pairwise relatedness (r) using codominant markers, such as microsatellites and enzymes. In contrast, only two estimators are proposed to use dominant markers, such as random amplified polymorphic DNAs (RAPDs) and amplified fragment length polymorphisms (AFLPs), in relatedness inference. They are both biased estimators, and their statistical properties and robustness to the sampling errors in allele frequency have not been investigated. In this short paper, I propose two new pairwise relatedness estimators for dominant markers, and compare them in precision, accuracy and robustness to sampling with the two previous estimators using simulations. It was found that the new estimator based on the least squares approach is unbiased when allele frequencies are known or estimated from a sample without correcting for sampling effects. It has, however, a low precision and as a result, an intermediate overall performance among the four estimators in terms of the mean squared deviation (MSD) of estimates from actual values of r. The new estimator based on a similarity index is slightly biased but has generally the lowest MSD among the four estimators compared, regardless of the number of loci, type of actual relationships, allele frequencies known or estimated from samples. Simulations also show that the confidence intervals estimated by bootstrapping are appropriate for different estimators provided that the number of loci used in the estimation is not small.
Molecular and ecological evidence for small‐scale isolation by distance in an endangered damselfly,Coenagrion mercuriale
Authors: WATTS P. C. , ROUQUETTE J. R. , SACCHERI I. J. , KEMP S. J. , THOMPSON D. J.
Published: October 2004

Coenagrion mercuriale(Charpentier) (Odonata: Zygoptera) is one of Europe's most threatened damselflies and is listed in the European Habitats directive. We combined an intensive mark‐release‐recapture (MRR) study with a microsatellite‐based genetic analysis forC. mercurialefrom the Itchen Valley, UK, as part of an effort to understand the dispersal characteristics of this protected species. MRR data indicate that adult damselflies are highly sedentary, with only a low frequency of interpatch movement that is predominantly to neighbouring sites. This restricted dispersal leads to significant genetic differentiation throughout most of the Itchen Valley, except between areas of continuous habitat, and isolation by distance (IBD), even though the core populations are separated by less than 10 km. An urban area separating some sites had a strong effect on the spatial genetic structure. Average pairwise relatedness between individual damselflies is positive at short distances, reflecting fine‐scale genetic clustering and IBD both within‐ and between‐habitat patches. Damselflies from a fragmented habitat have higher average kinship than those from a large continuous population, probably because of poorer dispersal and localized breeding in the former. Although indirect estimates of gene flow must be interpreted with caution, it is encouraging that our results indicate that the spatial pattern of genetic variation matches closely with that expected from direct observations of movement. These data are further discussed with respect to possible barriers to dispersal within the study site and the ecology and conservation ofC. mercuriale. To our knowledge, this is the first report of fine‐scale genetic structuring in any zygopteran species.
Conservation genetics and demographic history of the endangered Cape Fear shiner (Notropis mekistocholas)
Authors: SAILLANT E. , PATTON J. C. , ROSS K. E. , GOLD J. R.
Published: October 2004

We examined allelic variation at 22 nuclear‐encoded markers (21 microsatellites and one anonymous locus) and mitochondrial (mt)DNA in two geographical samples of the endangered cyprinid fish Notropis mekistocholas (Cape Fear shiner). Genetic diversity was relatively high in comparison to other endangered vertebrates, and there was no evidence of small population effects despite the low abundance reported for the species. Significant heterogeneity (following Bonferroni correction) in allele distribution at three microsatellites and in haplotype distribution in mtDNA was detected between the two localities. This heterogeneity may be due to reduced gene flow caused by a dam built in the early 1900s. Bayesian coalescent analysis of microsatellite variation indicated that effective population size of Cape Fear shiners has declined in recent times (11–25 435 years ago, with highest posterior probabilities between 126 and 2007 years ago) by one–two orders of magnitude, consistent with the observed decline in abundance of the species. A decline in effective size was not indicated by analysis of mtDNA, where sequence polymorphism appeared to carry the signature of an older expansion phase that dated to the Pleistocene (∼12 700 > 1 million years ago). Cape Fear shiners thus appear to have undergone an expansion phase following a glacial cycle but to have declined significantly in more recent times. These results suggest that rapidly evolving markers such as microsatellites may constitute a suitable tool when inferring recent demographic dynamics of populations.
Past and present patterns of connectivity among populations of four cryptic species of freshwater musselsVelesuniospp. (Hyriidae) in central Australia
Authors: HUGHES JANE , BAKER ANDREW M. , BARTLETT CHRISTOPHER , BUNN STUART , GOUDKAMP KATRINA , SOMERVILLE JEMMA
Published: October 2004

We examined genetic structure and levels of connectivity among subpopulations within each of four cryptic species belonging to the freshwater mussel genusVelesunio. We used allozymes and a fragment of the mitochondrial cytochromecoxidase I gene to examine genetic variation in populations from isolated waterholes, belonging to four major inland drainages in eastern Australia. Based on evidence from other invertebrates in the region we predicted that, in each species, we would find evidence of historical connectivity among populations from different drainages. This was clearly not the case, as for the two species that occurred in more than one drainage there was evidence of both current and past restriction to gene flow. Moreover, given the potential for extensive dispersal of these mussels through the river systems during flood times via their fish hosts, we predicted low levels of genetic variation among populations from waterholes in the same drainage. Contrary to our expectations, all four species showed some evidence of restricted gene flow among waterholes within drainages. This suggests that either (a) mussel larvae are not produced during flood times, when their fish hosts would be free to move between waterholes, or (b) mussel larvae are attached to their hosts at these times, but the fish movement is limited between waterholes.
No suggestion of hybridization between the vulnerable black‐faced impala (Aepyceros melampus petersi) and the common impala (A. m. melampus) in Etosha National Park, Namibia
Authors: LORENZEN ELINE D. , SIEGISMUND HANS R.
Published: October 2004

There are two recognized subspecies of impala in sub‐Saharan Africa: the common impala (Aepyceros melampus melampus) — widespread in southern and east Africa — and the vulnerable black‐faced impala (A. m. petersi) — found naturally in only a small enclave in southwest Africa. The Etosha National Park (NP) in Namibia harbours the largest and only protected‐area population of black‐faced impala, numbering some 1500 individuals. Due to translocations of the exotic common impala to commercial farms in Namibia during the past decades, the black‐faced impala in Etosha is faced with the potentially serious threat of hybridization posed by secondary contact with the common impala inhabiting bordering farms. Using eight microsatellite DNA markers, we analysed 127 black‐faced impala individuals from the five subpopulations in Etosha NP, to determine the degree, if any, of hybridization within the park. We found that (a) the black‐faced impala were highly genetically differentiated from the common impala (pairwise θ‐values ranged from 0.18 to 0.39 between subspecies; overall value = 0.27) and (b) black‐faced samples showed high levels of genetic variability [average expected heterozygosity (HE) = 0.61 ± 0.01 SE], although not as high as that observed in the common impala (averageHE = 0.69 ± 0.02 SE). (c) No hybridization between the subspecies in Etosha was suggested. A Bayesian Markov Chain Monte Carlo approach revealed clear distinction of individuals into groups according to their subspecies of origin, with a zero level of ‘genetic admixture’ among subspecies.
Recent habitat fragmentation due to roads can lead to significant genetic differentiation in an abundant flightless ground beetle
Authors: KELLER I. , NENTWIG W. , LARGIADÈR C. R.
Published: October 2004

Although habitat fragmentation is suspected to pose a major threat to biodiversity, its impact on abundant invertebrate species has been little investigated. We assessed the genetic population structure of the flightless ground beetleAbax parallelepipedusin a forest fragmented by two main roads and a highway using five microsatellite loci. We detected low levels of genetic differentiation, which was concordant with the high population densities of 632–1707 individuals/ha estimated with a mark–recapture method. A Mantel test detected a highly significant increase of pairwiseFST‐values with the number of roads between sampling locations. As expected, the most pronounced effect of the isolation due to roads was observed in the sample from the smallest fragment (highway exit loop), which was differentiated significantly from most other locations. However, no signs of a recent bottleneck or a loss of genetic variability were detected in this population, indicating a still relatively large effective population size (Ne). Computer simulations confirmed that the observedFST‐values were indeed compatible with aNeof a few hundred individuals in this fragment, assuming strong or absolute isolation since the construction of the roads. We discuss the implications of our findings for the conservation of abundant but poorly dispersing species in fragmented habitats.
Genetic variation in eastern North American and putatively introduced populations of Ceratocystis fimbriata f. platani
Authors: ENGELBRECHT C. J. B. , HARRINGTON T. C. , STEIMEL J. , CAPRETTI P.
Published: October 2004

The plant pathogenic fungus Ceratocystis fimbriata f. platani attacks Platanus species (London plane, oriental plane and American sycamore) and has killed tens of thousands of plantation trees and street trees in the eastern United States, southern Europe and Modesto, California. Nuclear and mitochondrial DNA fingerprints and alleles of eight polymorphic microsatellite markers of isolates of C. fimbriata from these regions delineated major differences in gene diversities. The 33 isolates from the eastern United States had a moderate degree of gene diversity, and unique genotypes were found at each of seven collection sites. Fingerprints of 27 isolates from 21 collection sites in southern Europe were identical with each other; microsatellite markers were monomorphic within the European population, except that three isolates differed at one locus each, due perhaps to recent mutations. The genetic variability of C. fimbriata f. platani in the eastern United States suggests that the fungus is indigenous to this region. The genetic homogeneity of the fungus in Europe suggests that this population has gone through a recent genetic bottleneck, perhaps from the introduction of a single genotype. This supports the hypothesis that the pathogen was introduced to Europe through Naples, Italy during World War II on infected crating material from the eastern United States. The Californian population may also have resulted from introduction of one or a few related genotypes because it, too, had a single nuclear and mitochondrial genotype and limited variation in microsatellite alleles.
Metabolic differentiation in actively swarming Salmonella
Authors: Kim Wook , Surette Michael G.
Published: October 2004

Most current paradigms of microbial metabolism have been derived from studying cells grown under a variety of nutrient compositions in aqueous environments. With recent advances in genomics and experimental techniques, alternative forms of bacterial growth are increasingly being explored. When propagated on nutrient‐rich semi‐solid media, several species of bacteria undergo a morphological differentiation into swarmers that are capable of migrating on surfaces. Recent studies indicate that swarmer differentiation represents much more than a motility phenotype, as several clinically important attributes are also co‐regulated. We demonstrate that migrating swarmer cells of Salmonella are metabolically differentiated compared to the vegetative swimmer cells grown in the same nutrient environment. Furthermore, once the cells have differentiated, the swarmers remain in this physiological state under conditions that do not promote the initial differentiation. The bacterium's capacity to override some of the classic paradigms of metabolic regulation established in aqueous environments represents a unique physiological response by the pathogen that may be advantageous in polymicrobial environments such as the host.
Genetic evidence for functional interactions between TolC and AcrA proteins of a major antibiotic efflux pump of Escherichia coli
Authors: Gerken Henri , Misra Rajeev
Published: October 2004

Genetic data have suggested that TolC, AcrA and AcrB constitute a major antibiotic efflux system in Escherichia coli. Through reversion analysis of an unstable and antibiotic‐sensitive TolC mutant (TolCP246R,S350C), we isolated extragenic suppressors that mapped within the acrRAB loci. DNA sequence analysis revealed that 18 isolates contained 10 different missense mutations within the acrA gene, whereas a single isolate had a missense mutation within the acrR gene, which codes for the acrAB repressor. Besides reversing the hypersensitivity phenotype of TolCP246R,S350C, AcrA and AcrR alterations elevated the mutant TolC protein level, thus indicating that the mechanism of suppression involves the stabilization of an unstable mutant TolC protein. Eight of the 10 AcrA alterations were clustered in the 202–265 region of the mature protein, whereas the other two suppressors affected residues 30 and 146. Based on the recently solved crystal structure of MexA, an AcrA counterpart from Pseudomonas aeruginosa, the regions encompassing residues 30 and 202–265 constitute the α+β‐domain of AcrA (MexA), whereas that of 146 form the α‐domain. The data suggest that residues of these two AcrA domains either directly or indirectly influence interactions with TolC. Curiously, the stability of three mutant AcrA proteins, bearing an L222Q, L222R or P265R substitution, became dependent on the presence of either wild‐type or mutant TolC. This dependence of the mutant AcrA proteins on TolC further supported the notion of a direct physical interaction between these two proteins. Because a mutation in acrR or acrAB expression from a multicopy plasmid also suppressed the TolCP246R,S350C defects, it indicated that wild‐type AcrA when produced in high levels presumably establishes similar interactions with the mutant TolC protein as do the suppressor forms of AcrA produced from the chromosomal copy. The AcrA‐mediated suppression of mutant TolC phenotypes and the stabilization of mutant TolC protein were dependent on AcrB, reflecting the existence of a functional complex between TolC and AcrAB in vivo.
HpaB from Xanthomonas campestris pv. vesicatoria acts as an exit control protein in type III‐dependent protein secretion
Authors: Büttner Daniela , Gürlebeck Doreen , Noël Laurent D. , Bonas Ulla
Published: October 2004

The hrp (hypersensitive response and pathogenicity) gene cluster of the plant pathogenic bacterium Xanthomonas campestris pv. vesicatoria encodes a type III secretion (TTS) system, which injects bacterial effector proteins into the plant cell. Here, we characterized hpaB (hpa, hrp‐associated), which encodes a pathogenicity factor with typical features of a TTS chaperone. We show that HpaB is important for the efficient secretion of at least five effector proteins but is dispensable for the secretion of non‐effectors such as XopA and the TTS translocon protein HrpF. GST pull‐down assays revealed that HpaB interacts with two unrelated effector proteins, AvrBs1 and AvrBs3, but not with XopA. The HpaB‐binding site is located within the first 50 amino acids of AvrBs3. This region also contains the targeting signal for HpaB‐dependent secretion, which is missing in HrpF and XopA. Intriguingly, the N‐termini of HrpF and XopA target the AvrBs3Δ2 reporter for translocation in a ΔhpaB mutant but not in the wild‐type strain. This indicates that HpaB plays an essential role in the exit control of the TTS system. Our data suggest that HpaB promotes the secretion of a large set of effector proteins and prevents the delivery of non‐effectors into the plant cell.
Release of DNA into the medium by competent Streptococcus pneumoniae: kinetics, mechanism and stability of the liberated DNA
Authors: Moscoso Miriam , Claverys Jean‐Pierre
Published: October 2004

The release of chromosomal DNA into culture media has been reported for several naturally transformable bacterial species, but a direct link between competence development and the liberation of DNA is generally lacking. Based on the analysis of strains with mutations in competence‐regulatory genes and the use of conditions favouring or preventing competence, we provide evidence that DNA release is triggered by the induction of competence in Streptococcus pneumoniae. Kinetic analyses revealed that whereas competence was maximal 20 min after addition of competence‐stimulating peptide, and then decreased, the amount of liberated DNA continued to increase and reached a maximum in stationary phase, when cells are no longer competent for DNA uptake. These data are not consistent with the proposal that release of DNA by a fraction of the population is coordinated with uptake by the remainder. Moreover, we observed that an unidentified DNase was specifically induced or released in competent cultures, and that together with the major pneumococcal endonuclease, EndA, it could degrade released DNA. Nearby complete abolition of release in a mutant lacking both the major autolysin, LytA, and the autolytic lysozyme, LytC, indicated that DNA liberation occurs by LytA‐LytC‐dependent cell lysis. These observations suggest that competence‐dependent DNA release is one facet of a more general phenomenon of sensitization to autolysis that reaches its maximum in stationary phase.