bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessing the optical performance of multifocal (diffractive) intraocular lenses
Authors: Eppig Timo , Scholz Katja , Langenbucher Achim
Published: August 2008

Background and purpose:  While the optical performance of monofocal refractive lenses can be measured quite easily, more efforts are required to assess the performance of multifocal lenses, due to imaging to several foci. The purpose of this study was to develop a rugged test setup for evaluation of the optical properties of intraocular lenses (IOLs) in conformity to the International Standard ISO 11979.

Methods:  We built a test setup in order to measure the point spread function and to determine the modulation transfer function (MTF) of IOLs. We measured three multifocal IOLs with (1) a diffraction limited model cornea and (2) an individualized aspheric model cornea which shows a significant amount of spherical aberration.

Results:  All the three IOL samples tested showed a different impact of spherical aberration on the MTF. The bispheric lenses (Alcon and Dr Schmidt) showed a degradation of the MTF and Strehl ratio with model (2) compared to model (1). In contrast, the MTF of the Tecnis lens, which has a prolate aspheric front surface, improved dramatically in combination with model (2).

Conclusion:  We demonstrated the functional capability of our measurement system by presentation of a set of working examples. Two different model corneas were used to study the influence of spherical aberration on the MTF of our working examples. An aspheric model cornea, which had already been shown to be suitable for testing monofocal aspherics, was shown to be well suited for testing aspheric multifocal lenses.
Habitual vs optimal distance visual acuity
Authors: Pointer Jonathan S.
Published: August 2008

Purpose:  The maintenance of a good level of vision is desirable for developmental and social reasons; it is also a requirement that should not be overlooked in the clinical research environment. This study set out to quantify and analyse any difference between ‘habitual’ (pre‐sight test) and ‘optimal’ (post‐refraction) distance visual acuity in an optometric population. It is intended that the outcome of this work will inform not only clinicians but also those undertaking vision research.

Methods:  Binocular logMAR visual acuity was determined at 6 m before and after optometric intervention in patients attending optometric practice for a routine sight test. Cases were recorded seriatim but restricted to the ‘core’ refraction range representative of typical optometric practice; three further exemption criteria included subject illiteracy, the necessity for a non‐standard test distance and contact lens wear. Over a 12‐month period, two‐thirds of patients examined satisfied the study inclusion criteria; it is the clinical data of these 1288 individuals that are described and analysed here.

Results:  These data provide a quantitative demonstration that an optometric intervention will most likely improve the habitual distance visual acuity of subjects, irrespective of gender, age group, time interval since last test, refractive status and whether or not the subject is a habitual spectacle wearer. The improvement found was typically within one logMAR chart line (<5 letters), being greatest in spectacle‐wearing teenagers and in individuals beyond retirement age (increasing to eight letters in elderly habitual non‐spectacle wearers); also in non‐wearers who left an interval of 2 years or more between sight tests.

Conclusions:  Clinical and laboratory‐based investigators are advised that a current and optimal refractive correction should be worn by subjects of all ages enrolled in vision‐related studies. Refractive defocus may introduce or exaggerate test outcome variability.
A pilot study of anisometropic amblyopia improved in adults and children by perceptual learning: an alternative treatment to patching
Authors: Chen Po‐Liang , Chen Jiann‐Torng , Fu Joa‐Jing , Chien Ke‐Hung , Lu Da‐Wen
Published: August 2008

Background:  To compare the effects of perceptual learning or patching on improving visual acuity and contrast sensitivity in patients with anisometropic amblyopia.

Methods:  Patients with anisometropic amblyopia received either patching or perceptual learning treatment. Corrected amblyopic logMAR visual acuity and contrast sensitivity function were measured at four‐weekly intervals until visual acuity stabilized or amblyopia resolved. Improvements in visual acuity, contrast sensitivity and resolution of amblyopia were compared between the two groups.

Results:  The mean visual acuities of the amblyopic eyes improved by 0.34 logMAR (95% CI: 0.22–0.47 logMAR) with patching and 0.25 logMAR (95% CI: 0.16–0.35 logMAR) with perceptual learning (p = 0.125). Resolution of amblyopia was achieved in 10 of 26 patients (38%) in the perceptual learning group and 17 of 27 patients (63%) in the patching group (p = 0.809). Amblyopia improved by two or more lines in 20 of 26 (76%) patients in the perceptual learning group and 26 of 27 (96%) patients in the patching group (p = 0.0001). The mean time for patching was 37.3 weeks (522.2 h) and the average number of training sessions in the perceptual learning group was 48 (29.5 h) (p = 0.0001).

Conclusions:  Visual acuity can be improved with perceptual learning and patching in older children and adult patients with anisometropic amblyopia. The improvements in visual acuity achieved with patching were one line better than those achieved with perceptual learning. Perceptual learning might provide an alternative treatment in patients with anisometropic amblyopia.
Drug‐induced ocular side‐effects with isotretinoin
Authors: Santodomingo‐Rubido Jacinto , Barrado‐Navascués Eva , Rubido‐Crespo María‐José
Published: August 2008

Whereas there are numerous reported ocular side‐effects from isotretinoin medication, we present the first case report of corneal steepening after systemic treatment with isotretinoin for seven and a half weeks. The case was associated with a significant drop in visual acuity which could not be explained from the refractive error change. All signs and symptoms were absent seven and a half weeks after the medication was withdrawn. The case indicates that eye care professionals need to be vigilant about the possibility of adverse ocular manifestations associated with the use of systemic medications.
Lens thickness with age and accommodation by optical coherence tomography
Authors: Richdale Kathryn , Bullimore Mark A. , Zadnik Karla
Published: August 2008

Purpose:  To utilize time‐domain optical coherence tomography (OCT) to measure changes in the crystalline lens with age and accommodation.

Methods:  A cross‐sectional study of pre‐presbyopic and presbyopic subjects was conducted. Amplitude of accommodation was measured with the push‐up test. Objective accommodation was measured with the Grand Seiko auto‐refractor and a Badal lens system. Lens thickness was measured with the Zeiss Visante OCT and an internal optometer. The data were analysed using correlation coefficients, linear regression, and by calculating the average change in lens thickness per diopter change in objective accommodation.

Results:  Twenty‐two subjects between the ages of 36 and 50 years completed the study. Subjective amplitude of accommodation ranged from 2.17 to 6.38 D. Objective accommodation ranged from 0.22 to 4.56 D. The mean lens thickness was 4.05 ± 0.20 mm. The mean change in lens thickness for up to a 5‐D accommodative stimulus ranged from 0.01 to 0.26 mm. The correlation coefficients were: age and subjective accommodation, r = −0.74; age and objective accommodation, r = −0.84; change in lens thickness and age, r = −0.65; change in lens thickness and subjective accommodation, r = 0.74; change in lens thickness and objective accommodation, r = 0.64; objective and subjective accommodation, r = 0.82 (all p < 0.01). An increase in lens thickness of 21 μm per year of age was determined by linear regression. For the subjects who showed at least 1 D of accommodative response on the Grand Seiko auto‐refractor, there was an increase of 51 ± 19 μm per dioptre of accommodation.

Conclusions:  Optical coherence tomography is a non‐invasive technique that can be used to quantify changes in the thickness of the crystalline lens. Subjective and objective measurements of accommodation, as well as age, were robustly correlated with the measured changes in lens thickness. Lens thickness changes with age and accommodation as measured with the Visante OCT compare well with previous findings using Scheimpflug photography and ultrasound.
THE BLUE ENAMELS IN THE BAROQUE DECORATIONS OF THE CHURCHES OF PALERMO, SICILY: FE2+‐COLOURED GLASSES FROM LIME KILNS*
Authors: ARTIOLI G. , NICOLA C. , MONTANA G. , ANGELINI I. , NODARI L. , RUSSO U.
Published: August 2008

Deep blue glasses coloured by octahedral Fe2+ cations are often reported as textbook examples of blue pigmentation. However, despite the possibility of laboratory synthesis under reducing conditions, to date there are no well‐reported occurrences of their production and use in the past. A thorough historical, ethnographic, mineralogical, and chemico‐physical investigation of the ‘smaltini di calcara’ from several baroque churches in Palermo, Sicily, has revealed that the blue enamels widely used for altar decorations in the 17th and 18th centuries are actually a unique case of ancient blue glasses pigmented by divalent iron cations in distorted octahedral coordination. This mixed‐alkali glass was accidentally produced under severely reducing conditions in the local kilns during production of lime.
PATTERNS OF IRON AGE HORSE SUPPLY: AN ANALYSIS OF STRONTIUM ISOTOPE RATIOS IN TEETH*
Authors: BENDREY R. , HAYES T. E. , PALMER M. R.
Published: August 2008

This paper presents a pilot study of strontium (Sr) isotope ratios from Iron Age horse tooth enamel samples. It compares 87Sr/86Sr ratios from horse teeth to estimates for local ranges of biologically available strontium, to investigate whether horses were being bred at the sites where their remains were discovered. A horse from Middle Iron Age Rooksdown, Hampshire, was not bred at the site but, rather, came from as far away as Wales, Scotland or continental Europe. Horse teeth from Middle Iron Age Bury Hill, Hampshire, returned 87Sr/86Sr values typical of local chalkland.
Exploring Periodization in the Classroom: A Seminar on the Early‐Modern World
Authors: Clossey Luke , Marriott Brandon
Published: August 2008

The idea of an ‘early‐modern world’ has come into common use despite historians’ lack of enthusiasm for it as a concept. Possible implications of teleology, eurocentrism, and artificial homogenization not unfairly discourage professional confidence in it. The article describes an undergraduate seminar that takes advantage of the professional uncertainty about early modernity. As they move through a series of thematically organized readings, participants construct and revamp a potentially multifaceted definition of the early‐modern world. Simultaneously, each student specializes in a chosen region and uses that place as a test case to evaluate the working definition as it evolves. The result is a learning experience that maximizes both cooperative and individual research to achieve a balance between the specific and the global.
Social Support for Physical Activity of Middle School Students
Authors: Robbins Lorraine B. , Stommel Manfred , Hamel Lauren M.
Published: August 2008

ABSTRACT
Objective: To explore gender and age differences in social support and their relationship with physical activity.

Design and sample: This cross‐sectional study with enhanced reliability due to repeated measures involved 105 boys and 101 girls.

Measurements: Information on sources and forms of social support, as well as physical activity, was obtained from students, who completed the same questionnaire twice, 2 weeks apart.

Results: Boys, compared with girls, were more likely to name fathers and less likely to identify sisters. Compared with older boys, older girls were less likely to identify fathers. Older girls were less likely than both younger girls and older boys to name brothers. Students who identified fathers reported more minutes and days of physical activity and had a stronger physical activity self‐definition than those who did not name fathers. Students who selected peers and sisters had more minutes of physical activity and a stronger physical activity self‐definition, respectively, than those who did not name peers and sisters. Transportation and encouragement were related to physical activity.

Conclusions: Gender differences in social support are not uniform across age groups. Awareness of these differences can inform the development of appropriate physical activity programs.
Translation of the Multidimensional Health Locus of Control Scales for Users of American Sign Language
Authors: Samady Waheedy , Sadler Georgia Robins , Nakaji Melanie , Malcarne Vanessa L.
Published: August 2008

ABSTRACT
This paper describes the translation of the Multidimensional Health Locus of Control (MHLC) scales into American Sign Language (ASL). Translation is an essential first step toward validating the instrument for use in the Deaf community, a commonly overlooked minority community. This translated MHLC/ASL can be utilized by public health nurses researching the Deaf community to create and evaluate targeted health interventions. It can be used in clinical settings to guide the context of the provider‐patient dialogue. The MHLC was translated using focus groups, following recommended procedures. 5 bilingual participants translated the MHLC into ASL; 5 others back‐translated the ASL version into English. Both focus groups identified and addressed language and cultural problems before the final ASL version of the MHLC was permanently captured by motion picture photography for consistent administration. Nine of the 24 items were directly translatable into ASL. The remaining items required further discussion to achieve cultural equivalence with ASL expressions. The MHLC/ASL is now ready for validation within the Deaf community.
Clinical Practice of Functional Electrical Stimulation: From “Yesterday” to “Today”
Authors: Dimitrijevic Milan R.
Published: August 2008

Abstract:  Functional electrical stimulation (FES) is an accepted treatment method for paresis or paralysis after spinal cord and head injury as well as stroke and other neurological upper motor neuron disorders. At the beginning, FES worked like an electrophysiological brace for the correction of drop foot of patients after a stroke. When analyzing early accomplishments, it becomes evident that FES was influenced rather by technological and biomedical engineering development than by contemporary knowledge on neurocontrol of movement in individuals with upper motor neuron paralysis. Nevertheless, with better understanding of pathophysiology of spasticity and neurocontrol of impaired movement, FES advanced from an electrophysiological brace to a treatment modality for the improvement of muscle control, neuroaugmentation of residual movements, and supportive procedure for “spontaneous recovery” of motor control. In the present article we shall illustrate barriers which delayed FES to be applied in clinical practice of neuron rehabilitation from “Yesterday” to “Today.” We shall discuss the importance to apply FES early after the onset of neurological conditions to prevent disuse of noninjured portions of the CNS. Moreover, FES can play a significant role in the supporting processes of neuroplasticity in the subacute phase of upper motor neuron dysfunction. Therefore, the electrophysiological brace of “Yesterday” provides “Today” a correction of missing neuromuscular function. At the same time, it is an active external device for the correction of motor deficits interacting with the somatosensory‐motor integration. Thus, “Yesterday” and “Today” of the same technological approach can be very different, thanks to a different understanding and assessment of “external” and “internal” components of human motor control.
Selective Stimulation of Autonomic Nerves and Recording of Electroneurograms in a Canine Model
Authors: Rozman Janez , Pečlin Polona
Published: August 2008

Abstract:  The article presents the results of modeling, design, and experimental testing of a multielectrode spiral cuff (CUFF) to determine to what extent a CUFF could be used for selective stimulation of different types of nerve fibers within particular compartments and for selective recording of electoneurograms (ENGs) from particular compartments of the peripheral autonomic nerve. The CUFF was implanted on the left cervical vagus nerve (LVN) of a dog. The relative positions of the particular nerve regions that innervated the cardiovascular (CV) and respiratory system (RS) were identified by delivering the stimuli to the particular group of three electrodes (GTE). The stimuli caused both selective stimulation of mainly B fibers within the particular compartments, and differential block of A fibers by membrane hyperpolarization. It was shown that when the stimuli were delivered to GTE9, the heart rate began to fall and when the stimuli were delivered to GTE4, the rate of breathing decreased. The defined and randomly chosen GTEs were used also as recording GTEs while CV or RS were stimulated by carotid artery massage, epinephrine injection, and noninvasive positive end‐expiratory pressure ventilation (NIPEEPV). Results demonstrate that the function of a particular internal organ can be modulated via the selective stimulation of the innervating compartment of the peripheral nerve. Results also showed that stimulations elicited site‐specific changes in ENG power spectra recorded from the particular compartments of the LVN.
Functional Electrical Stimulation of Denervated Muscles: An Experimental Evaluation
Authors: Salmons Stanley , Jarvis Jonathan C.
Published: August 2008

Abstract:  For many years there has been a dearth of effective treatment options for the severe wasting and secondary consequences of motor nerve injury. In recent years, however, an intensive regime of electrical stimulation has been shown to have considerable therapeutic benefits. This article reviews the results of an extensive study designed to address the clinically relevant issues in an appropriate animal model. The study reveals both the benefits and the limitations of the technique, but strongly endorses the therapeutic advantages of introducing a program of stimulation during the initial, nondegenerative phase of the muscle response to nerve or root injury.
Functional Electrical Stimulation of Long‐term Denervated, Degenerated Human Skeletal Muscle: Estimating Activation Using T2‐Parameter Magnetic Resonance Imaging Methods
Authors: Mandl Thomas , Meyerspeer Martin , Reichel Martin , Kern Helmut , Hofer Christian , Mayr Winfried , Moser Ewald
Published: August 2008

Abstract:  Functional electrical stimulation (FES) of long‐term denervated, degenerated human skeletal muscle has proven to be a suitable method for improving a number of physiological parameters. The underlying mechanisms of activation of a denervated muscle fiber can be described with suitably modified and extended Hodgin‐Huxley type models, coupled with three‐dimensional (3D) finite element models of the surrounding electrical field. Regions of activation within a muscle can be determined using a 3D computer model. However, simulation results have not yet been validated experimentally. During and immediately after exercise, muscle shows increased T2‐relaxation times. It is thus possible to estimate muscle activation noninvasively and spatially resolved with the magnetic resonance imaging (MRI) method of T2 mapping, which was, therefore, chosen as a suitable validation approach. Six patients were scanned prior to FES training with a multislice multiecho MSME‐sequence at 3 Tesla and then asked to perform one of their regular daily training‐sessions (leg extensions). Subjects were then repositioned in the MR‐scanner and two to five postexercise scans were recorded. Pre‐ and postexercise scans were coregistered and T2‐parameter maps were calculated. Regions of interest (ROIs) were drawn manually around quadriceps femoris and its antagonists. Activation was detected in all patients. In well‐trained patients, activation in the quadriceps was found to be considerably higher than in its antagonists. These experimental results will help further improve existing models of FES of denervated degenerated human skeletal muscle.
A Novel Approach to Simulate Hodgkin–Huxley‐like Excitation With COMSOL Multiphysics
Authors: Martinek Johannes , Stickler Yvonne , Reichel Martin , Mayr Winfried , Rattay Frank
Published: August 2008

Abstract:  A proof of concept for the evaluation of external nerve and muscle fiber excitation with the finite element software COMSOL Multiphysics, formerly known as FEMLAB, is presented. This software allows the simultaneous solution of fiber excitation by 1D models of the Hodgkin‐Huxley type which are embedded in a volume conductor where the electric field is mainly dominated by the electrode currents. This way the presented bidomain model includes the interaction between electrode currents and transmembrane currents during the excitation process. Especially for direct muscle fiber stimulation (cardiac muscle, denervated muscle) the effects from secondary currents from large populations of excited fibers seem to be significant. The method has many applications, for example, the relation between stimulus parameters and fiber recruitment can be analyzed.
Real‐time Polymerase Chain Reaction to Follow the Response of Muscle to Training
Authors: Moore Lauren M. , Fisher Andrew G. , Coulson Judy M. , Salmons Stanley , Jarvis Jonathan C.
Published: August 2008

Abstract:  The adaptive response of muscle to changes in activity or loading can take many weeks. Changes in the levels of RNA within a muscle fiber can give an early indication of the nature of the response of that fiber to changes in activity or loading. We have designed a new primer set for quantitative polymerase chain reaction (PCR) that will allow us to follow these early transcriptional changes in rat muscle, and have shown that analysis can be performed by standard techniques on as little as 5 mg of muscle, an amount that can be obtained by needle biopsy.
Automatic Control of a Drop‐Foot Stimulator Based on Angle Measurement Using Bioimpedance
Authors: Nahrstaedt Holger , Schauer Thomas , Shalaby Raafat , Hesse Stefan , Raisch Jörg
Published: August 2008

Abstract:  The topic of this contribution is iterative learning control of a drop‐foot stimulator in which a predefined angle profile during the swing phase is realized. Ineffective dorsiflexion is compensated by feedback‐controlled stimulation of the muscle tibialis anterior. The ankle joint measurement is based on changes in the bioimpedance (BI) caused by leg movements. A customized four‐channel BI measurement system was developed. The suggested control approach and the new measurement method for the joint angle were successfully tested in preliminary experiments with a neurologically intact subject. Reference angle measurements were taken with a marker‐based optical system. An almost linear relation between joint angle and BI was found for the angle range applicable during gait. The desired angle trajectory was closely tracked by the iterative learning controller after three gait cycles. The final root mean square tracking error was below 5°.
Cardiorespiratory, Metabolic, and Biomechanical Responses During Functional Electrical Stimulation Leg Exercise: Health and Fitness Benefits
Authors: Davis Glen M. , Hamzaid Nur A. , Fornusek Ché
Published: August 2008

Abstract:  Functional electrical stimulation (FES)‐induced leg exercise offers the potential for individuals with lower‐limb paralysis to otherwise gain some benefits conferred by leg exercise. Although its original intent is to reactivate the leg muscles to produce functional upright mobility, as a rehabilitation therapy, FES‐evoked exercise increases the whole‐body metabolism of individuals with spinal cord injury (SCI) so that they may gain general and localized health and fitness benefits. The physiological and psychosocial responses during FES‐evoked cycling, standing, rowing, leg extension, or stepping have been extensively explored for over 20 years. Some of the advantages of such exercise include augmented cardiorespiratory fitness, promotion of leg blood circulation, increased activity of specific metabolic enzymes or hormones, greater muscle volume and fiber size, enhanced functional exercise capacity such as strength and endurance, and altered bone mineral density. Positive psychosocial adaptations have also been reported among SCI individuals who undergo FES exercise. This article presents a position review of the available literature on the effects of FES‐evoked exercise since the earliest date until 2007, to warrant a conclusion about the current status and potential of FES‐evoked exercise for paralyzed people.
Likelihood of Illegal Alcohol Sales at Professional Sport Stadiums
Authors: Toomey Traci L. , Erickson Darin J. , Lenk Kathleen M. , Kilian Gunna R.
Published: August 2008

Background:  Several studies have assessed the propensity for illegal alcohol sales at licensed alcohol establishments and community festivals, but no previous studies examined the propensity for these sales at professional sport stadiums. In this study, we assessed the likelihood of alcohol sales to both underage youth and obviously intoxicated patrons at professional sports stadiums across the United States, and assessed the factors related to likelihood of both types of alcohol sales.

Methods:  We conducted pseudo‐underage (i.e., persons age 21 or older who appear under 21) and pseudo‐intoxicated (i.e., persons feigning intoxication) alcohol purchase attempts at stadiums that house professional hockey, basketball, baseball, and football teams. We conducted the purchase attempts at 16 sport stadiums located in 5 states. We measured 2 outcome variables: pseudo‐underage sale (yes, no) and pseudo‐intoxicated sale (yes, no), and 3 types of independent variables: (1) seller characteristics, (2) purchase attempt characteristics, and (3) event characteristics. Following univariate and bivariate analyses, we a separate series of logistic generalized mixed regression models for each outcome variable.

Results:  The overall sales rates to the pseudo‐underage and pseudo‐intoxicated buyers were 18% and 74%, respectively. In the multivariate logistic analyses, we found that the odds of a sale to a pseudo‐underage buyer in the stands was 2.9 as large as the odds of a sale at the concession booths (30% vs. 13%; p = 0.01). The odds of a sale to an obviously intoxicated buyer in the stands was 2.9 as large as the odds of a sale at the concession booths (89% vs. 73%; p = 0.02).

Conclusions:  Similar to studies assessing illegal alcohol sales at licensed alcohol establishments and community festivals, findings from this study shows the need for interventions specifically focused on illegal alcohol sales at professional sporting events.
Acute Ethanol Effects on Local Cerebral Glucose Utilization in Select Central Nervous System Regions of Adolescent Alcohol‐Preferring (P) and Alcohol‐Nonpreferring (NP) Rats
Authors: Strother Wendy N. , Lumeng Lawrence , McBride William J.
Published: August 2008

Background:  Alcohol abuse among adolescents is a major health and developmental problem. The 2‐[14C]deoxyglucose (2‐DG) technique allows for the in vivo quantification of local cerebral glucose utilization (LCGU) as a measure of functional neuronal activity.

Methods:  Local cerebral glucose utilization rates were examined after acute ethanol administration within selected brain regions of adolescent alcohol‐preferring (P) and ‐nonpreferring (NP) rats. Postnatal day 45 male P and NP rats were injected with saline or 1.0 g/kg ethanol, i.p., 10 minutes prior to an intravenous bolus of [14C]‐2‐deoxyglucose (125 μCi/kg). Image densities were determined using quantitative autoradiography and LCGU values calculated.

Results:  Acute ethanol injection significantly decreased LCGU rates in select brain regions including the olfactory tubercles, the frontal cortex (Fr), and subregions of the posterior hippocampus (pCA1 and pCA3). Acute ethanol had no significant effects on LCGU rates in any region of the adolescent NP rats. Significant basal LCGU rate differences were apparent between the rat lines in a nearly global fashion with adolescent P rats having much higher basal LCGU rates compared with adolescent NP rats.

Conclusions:  These findings suggest that the adolescent P and NP rats are less sensitive to the effects of acute ethanol than their adult counterparts. The adolescent P rat is relatively more sensitive to the initial effects of acute ethanol in select brain regions as compared with the adolescent NP rat. Additionally, the innate hyper‐excited state of the adolescent P central nervous system is a likely factor in the development of their high alcohol drinking behaviors.
Markers of Oxidative Stress and Systemic Vasoconstriction in Pregnant Women Drinking ≥48 g of Alcohol per Day
Authors: Signore Caroline , Aros Sofía , Morrow Jason D. , Troendle James , Conley Mary R. , Flanigan Elizabeth Y. , Cassorla Fernando , Mills James L.
Published: August 2008

Background:  The precise pathway by which alcohol causes the characteristic features of fetal alcohol spectrum disorders is unknown. Proposed mechanisms for fetal injury from maternal alcohol use include cellular damage from oxidative stress and impaired fetal oxygenation related to maternal systemic vasoconstriction. Our objective was to compare the levels of urinary markers of oxidative stress and systemic vasoconstriction between women consuming large amounts of alcohol during pregnancy and women who did not drink alcohol during pregnancy.

Methods:  Pregnant women consuming ≥48 g alcohol per day (n = 29) on average and pregnant women who abstained from alcohol use (n = 39) were identified using detailed interviews and home visits. Random maternal urine specimens were collected. Urinary levels of the oxidative stress marker, 8‐isoprostane F2α, and of the vasoactive prostaglandin metabolites, 2,3‐dinor‐6‐keto‐prostaglandin F1α (a vasodilator) and 11‐dehydro‐thromboxane B2 (a vasoconstrictor), were measured using mass spectrometric methods. All analyte levels were corrected for urinary creatinine.

Results:  In crude analyses, there was no significant difference in 8‐isoprostane F2α between pregnant drinkers and nondrinkers (2.16 vs. 2.08 ng/mg creatinine, respectively, p = 0.87). There were no significant differences between the drinking and nondrinking groups in levels of 2,3‐dinor‐6‐keto‐prostaglandin F1α (1.03 vs. 1.17 ng/mg creatinine, repectively, p = 0.50), 11‐dehydro‐thromboxane B2 (0.72 vs. 0.59 ng/mg creatinine, respectively, p = 0.21), or the ratio of vasodilatory metabolite to vasoconstrictive metabolite (1.73 vs. 2.72, respectively, p = 0.14). Adjusting for maternal age, marital status, smoking, and gestational age at sampling did not substantially alter the results.

Conclusion:  Our results show no difference in levels of urinary eicosanoid markers of oxidative stress and systemic vasoconstriction between pregnant women who drink heavily and pregnant women who abstain. These findings speak against a role for maternal oxidative stress or systemic vasoconstriction in the pathogenesis of alcohol damage to the fetus.
Biphasic Effects of Moderate Drinking on Prolactin During Lactation
Authors: Mennella Julie A. , Pepino Marta Yanina
Published: August 2008

Background:  Contrary to the popular lore that encourages women to drink alcohol as an aid to lactation, we previously showed that alcohol consumption disrupted lactational performance and the hormonal milieu of the lactating mother in the short term.

Methods:  Thirteen lactating women participated in a 4‐session, double‐blind, 2 × 2 within‐subject study to test several hypotheses related to the effects of alcohol on prolactin (PRL) responses and milk yield over time. The two within‐subject factors were beverage condition (control or 0.4 g/kg dose of alcohol) and pumping condition (pumping occurred at fixed intervals once or twice during the 5.3‐hour session). Plasma PRL, blood alcohol concentrations (BAC), and milk yield were measured.

Results:  Alcohol consumption increased basal PRL levels (p < 0.0001) and modified the PRL response to pumping (p < 0.0001) but the directionality of the response depended on when pumping occurred along the BAC curve. Pumping enhanced PRL response when it occurred during the ascending BAC limb but blunted the response when it occurred during the descending limb, providing evidence that the effects were transient and of a biphasic nature. The slower the alcohol was metabolized, the greater the relative PRL response to breast pumping (p < 0.05). The dynamics of the PRL response between pumping sessions was also altered if women drank. If women pumped within the hour after drinking alcohol, the PRL response during the next pumping some 1.5 hours later, was delayed by a few minutes. Milk yield was significantly lower after drinking alcohol but such deficits were not significantly related to PRL or the speed at which alcohol was eliminated.

Conclusions:  Effects of alcohol on suckling‐induced PRL were biphasic in nature, but could not explain the deficits in lactational performance. Such findings provide further evidence that the dynamic changes in neuroendocrine state are integrally involved in alcohol’s effects over time and underscore the complexity of lactation.
Effects of Functional Polymorphisms Related to Catecholaminergic Systems on Changes in Blood Catecholamine and Cardiovascular Measures After Alcohol Ingestion in the Japanese Population
Authors: Nishimura Fusae T. , Kimura Yukiko , Abe Shuntaro , Fukunaga Tatsushige , Minami Junichi , Tanii Hideji , Saijoh Kiyofumi
Published: August 2008

Background: The polymorphism of human aldehyde dehyrogenase‐2 (ALDH2) Glu487Lys is well known to be a crucial factor underlying the genetic background for alcohol sensitivity in Asian populations. Subjects with the inactive Lys487allele show a marked increase in blood acetaldehyde level after alcohol intake, which results in facial flushing and various cardiovascular‐related symptoms. However, other polymorphisms related to catecholaminergic systems that tightly regulate the activity of the sympathetic nervous system may also influence the physiological changes after acute alcohol intake.

Methods: We investigated whether, together with theALDH2Gly487Lys andADH1BArg47His genotype, putative functionally important polymorphisms, including 9 loci in 7 human genes, were associated with changes in blood catecholamine levels and cardiovascular measures after alcohol ingestion. Forty‐nine young Japanese males were subjected to blood catecholamine analysis after alcohol ingestion. Among them, 28 were also subjected to heart rate variability and blood pressure analysis. The contribution of polymorphisms to the alcohol‐induced response was analyzed by multiple regression analysis.

Results: Among the polymorphisms examined in this study, haplotypes of the phenylethanolamineN‐methyltransferase (PNMT) promoter [(−182bpG/A)_(−387bpG/A)] and catechol‐O‐methyltransferase (COMT) exon 4 [(Ex4 + 119bpC/G)_(Ex4 + 138bpG/A), Leu136Leu_Val158Met] are suggested to have functionally important effects on alcohol‐induced cardiovascular symptoms by affecting blood catecholamine levels. The neuropeptide Y (NPY) promoter C‐1450T genotype is also suggested to be involved in the individual differences in regulation of catecholamine secretion.

Conclusions: This study suggested that these common polymorphisms of genes related to catecholaminergic systems, as well as those of the alcohol metabolizing system, are significant for understanding the basis of individual differences in alcohol sensitivity.
Flood Risk Assessment in the Netherlands: A Case Study for Dike Ring South Holland
Authors: Jonkman Sebastiaan N. , Kok Matthijs , Vrijling Johannes K.
Published: August 2008

Large parts of the Netherlands are below sea level. Therefore, it is important to have insight into the possible consequences and risks of flooding. In this article, an analysis of the risks due to flooding of the dike ring area South Holland in the Netherlands is presented. For different flood scenarios the potential number of fatalities is estimated. Results indicate that a flood event in this area can expose large and densely populated areas and result in hundreds to thousands of fatalities. Evacuation of South Holland before a coastal flood will be difficult due to the large amount of time required for evacuation and the limited time available. By combination with available information regarding the probability of occurrence of different flood scenarios, the flood risks have been quantified. The probability of death for a person in South Holland due to flooding, the so‐called individual risk, is small. The probability of a flood disaster with many fatalities, the so‐called societal risk, is relatively large in comparison with the societal risks in other sectors in the Netherlands, such as the chemical sector and aviation. The societal risk of flooding appears to be unacceptable according to some of the existing risk limits that have been proposed in literature. These results indicate the necessity of a further societal discussion on the acceptable level of flood risk in the Netherlands and the need for additional risk reducing measures.
Insurance Market Dynamics: Between Global Developments and Local Contingencies
Authors: Cummins J. David , Venard Bertrand
Published: August 2008

Abstract

Insurance markets have changed radically and deeply in the past twenty years. Deregulation, globalization of insurance institutions, intensified competition, electronic commerce, bancassurance, and the emergence of new risks are among the challenges faced by insurance markets. Although important global trends are reshaping insurance markets, the emphasis on globalization overlooks the local diversity of insurance markets worldwide. This article reviews the global developments and local factors affecting insurance markets and evaluates the advantages and disadvantages of globalization. Among the important global trends are the increasing sophistication of insurance products, the globalization of risk diversification through reinsurance, the emergence of mega‐financial intermediaries, and the growing importance of supranational agencies such as the World Bank and the World Trade Organization. On the other hand, there remains significant heterogeneity among countries and regions that has a profound impact on insurance markets. Among the important local differences are political, legal, and cultural components as well as differences in financial markets, taxation, regulatory systems, insurer investment strategies, and insurance distribution systems.
The Impact of Deregulation on Efficiency: An Analysis of Life Insurance Industry in Taiwan From 1981 to 2004
Authors: Jeng Vivian , Lai Gene C
Published: August 2008

Abstract

We examine the impact of deregulation and liberalization (D&L) on the efficiency of the Taiwanese life insurance industry from 1981 to 2004. We utilize the data envelopment analysis (DEA) to measure the efficiency performances and the Malmquist index approach to measure changes in efficiency and productivity over time. Both the DEA and Malmquist results show that the old domestic firms have been slightly impacted by the new competitors around 1992–1994 (the end of foreign and new local entry period and the beginning of post‐D&L period). More important, our results show that the D&L does not have major adverse impact on the technical, cost, and revenue efficiency performances of existing domestic firms in the long run. The dominance of existing domestic firms has declined but persists throughout the sample period. In addition, our results show that it is relatively easy for new firms to become technically efficient in just few years after entering the market, but it is more difficult for them to become efficient in cost and revenue efficiency. We, thus, suggest that a new market entrant should take advantage of the existing mechanisms by acquiring an old (existing) firm, rather than establish a new one, if a new entrant wants to become efficient in cost and revenue efficiency in a short time.
Haplotype‐Based Regression Analysis and Inference of Case–Control Studies with Unphased Genotypes and Measurement Errors in Environmental Exposures
Authors: Lobach Iryna , Carroll Raymond J. , Spinka Christine , Gail Mitchell H. , Chatterjee Nilanjan
Published: August 2008

SummaryIt is widely believed that risks of many complex diseases are determined by genetic susceptibilities, environmental exposures, and their interaction.Chatterjee and Carroll(2005,Biometrika92,399–418) developed an efficient retrospective maximum‐likelihood method for analysis of case–control studies that exploits an assumption of gene–environment independence and leaves the distribution of the environmental covariates to be completely nonparametric.Spinka, Carroll, and Chatterjee(2005,Genetic Epidemiology29,108–127) extended this approach to studies where certain types of genetic information, such as haplotype phases, may be missing on some subjects. We further extend this approach to situations when some of the environmental exposures are measured with error. Using a polychotomous logistic regression model, we allow disease status to haveK+ 1 levels. We propose use of a pseudolikelihood and a related EM algorithm for parameter estimation. We prove consistency and derive the resulting asymptotic covariance matrix of parameter estimates when the variance of the measurement error is known and when it is estimated using replications. Inferences with measurement error corrections are complicated by the fact that the Wald test often behaves poorly in the presence of large amounts of measurement error. The likelihood‐ratio (LR) techniques are known to be a good alternative. However, the LR tests are not technically correct in this setting because the likelihood function is based on an incorrect model, i.e., a prospective model in a retrospective sampling scheme. We corrected standard asymptotic results to account for the fact that the LR test is based on a likelihood‐type function. The performance of the proposed method is illustrated using simulation studies emphasizing the case when genetic information is in the form of haplotypes and missing data arises from haplotype‐phase ambiguity. An application of our method is illustrated using a population‐based case–control study of the association between calcium intake and the risk of colorectal adenoma.
Multivariate Markov Process Models for the Transmission of Methicillin‐ResistantStaphylococcus Aureusin a Hospital Ward
Authors: Drovandi C. C. , Pettitt A. N.
Published: August 2008

SummaryMethicillin‐resistantStaphylococcus Aureus(MRSA) is a pathogen that continues to be of major concern in hospitals. We develop models and computational schemes based on observed weekly incidence data to estimate MRSA transmission parameters. We extend the deterministic model ofMcBryde, Pettitt, and McElwain(2007,Journal of Theoretical Biology245,470–481) involving an underlying population of MRSA colonized patients and health‐care workers that describes, among other processes, transmission between uncolonized patients and colonized health‐care workers and vice versa. We develop new bivariate and trivariate Markov models to include incidence so that estimated transmission rates can be based directly on new colonizations rather than indirectly on prevalence. Imperfect sensitivity of pathogen detection is modeled using a hidden Markov process. The advantages of our approach include (i) a discrete valued assumption for the number of colonized health‐care workers, (ii) two transmission parameters can be incorporated into the likelihood, (iii) the likelihood depends on the number of new cases to improve precision of inference, (iv) individual patient records are not required, and (v) the possibility of imperfect detection of colonization is incorporated. We compare our approach with that used byMcBryde et al. (2007)based on an approximation that eliminates the health‐care workers from the model, uses Markov chain Monte Carlo and individual patient data. We apply these models to MRSA colonization data collected in a small intensive care unit at the Princess Alexandra Hospital, Brisbane, Australia.
Inference for Kappas for Longitudinal Study Data: Applications to Sexual Health Research
Authors: Ma Yan , Tang Wan , Feng Changyong , Tu Xin M.
Published: August 2008

Summary Analysis of instrument reliability and rater agreement is used in a wide range of behavioral, medical, psychosocial, and health‐care‐related research to assess psychometric properties of instruments, consensus in disease diagnoses, fidelity of psychosocial intervention, and accuracy of proxy outcomes. For categorical outcomes, Cohen's kappa is the most widely used index of agreement and reliability. In many modern‐day applications, data are often clustered, making inference difficult to perform using existing methods. In addition, as longitudinal study designs become increasingly popular, missing data have become a serious issue, and the lack of methods to systematically address this problem has hampered the progress of research in the aforementioned fields. In this article, we develop a novel approach based on a new class of kappa estimates to tackle the complexities involved in addressing missing data and other related issues arising from a general multirater and longitudinal data setting. The approach is illustrated with real data in sexual health research.
A New Exact and More Powerful Unconditional Test of No Treatment Effect from Binary Matched Pairs
Authors: Lloyd Chris J.
Published: August 2008

Summary We consider the problem of testing for a difference in the probability of success from matched binary pairs. Starting with three standard inexact tests, the nuisance parameter is first estimated and then the residual dependence is eliminated by maximization, producing what I call an E+M P‐value. The E+M P‐value based on McNemar's statistic is shown numerically to dominate previous suggestions, including partially maximized P‐values as described in Berger and Sidik (2003, Statistical Methods in Medical Research12, 91–108). The latter method, however, may have computational advantages for large samples.
Efficient Statistical Inference Procedures for Partially Nonlinear Models and their Applications
Authors: Li Runze , Nie Lei
Published: August 2008

SummaryMotivated by an analysis of a real data set in ecology, we consider a class of partially nonlinear models where both a nonparametric component and a parametric component are present. We develop two new estimation procedures to estimate the parameters in the parametric component. Consistency and asymptotic normality of the resulting estimators are established. We further propose an estimation procedure and a generalizedF‐test procedure for the nonparametric component in the partially nonlinear models. Asymptotic properties of the newly proposed estimation procedure and the test statistic are derived. Finite sample performance of the proposed inference procedures are assessed by Monte Carlo simulation studies. An application in ecology is used to illustrate the proposed methods.
Modeling Time Series of Animal Behavior by Means of a Latent‐State Model with Feedback
Authors: Zucchini Walter , Raubenheimer David , MacDonald Iain L.
Published: August 2008

Summary We describe a family of models developed for time series of animal feeding behavior. The models incorporate both an unobserved state, which can be interpreted as the motivational state of the animal, and a mechanism for feedback to this state from the observed behavior. We discuss methods for evaluating and maximizing the likelihood of an observed series of behaviors, and thereby estimating parameters, and for inferring the most likely sequence of underlying states. We indicate several extensions of the models, including the incorporation of random effects. We apply these methods in an analysis of the feeding behavior of the caterpillar Helicoverpa armigera, and thereby demonstrate the potential of this family of models as a tool in the investigation of behavior.