bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Simulation of the Spontaneous Penetration of Liquids into Cylindrical Capillaries
Authors: FICK ANTHONY D. , BORHAN ALI
Published: November 2006

Abstract:  Dynamics of spontaneous capillary penetration of a liquid into a cylindrical pore is studied numerically over the entire duration of an experiment, including the initial stages of penetration during which inertial effects are dominant. Partial slip in the vicinity of the moving contact‐line is allowed by using an empirical constitutive relation between the dynamic contact angle and contact line speed in order to avoid the stress singularity arising from the presence of the moving contact line on the solid wall. A finite‐difference scheme on a staggered body‐fitted grid is used to solve for the time‐dependent flow field and to determine the time evolution of the shape of the advancing meniscus. The results of dynamic simulations of capillary rise under both normal and microgravity conditions are compared with the reported experimental observations. The simulation results are found to be in good agreement with the experimental measurements in both cases. Numerical simulations capture the different flow regimes identified in previous studies of spontaneous capillary penetration. The velocity dependence of the dynamic contact line is found to have a significant effect on kinetics of wetting in the intermediate‐time flow regime, wherein the capillary force is balanced by convective losses.
Self‐Rewetting Fluids
Authors: ABE YOSHIYUKI
Published: November 2006

Abstract:  This paper reviews a series of my heat transfer studies of on the so‐called “self‐rewetting” fluids, in which the Marangoni effect due to concentration gradient and the thermocapillary flow cooperatively result in a strong liquid inflow at the nucleation sites in the course of boiling. First of all, the background of the study and our first attempt at heat transfer enhancement in microgravity boiling are introduced. Succeeding fundamental vapor bubble experiments are then briefly depicted. The current progress for applications to space and terrestrial thermal management devices, the main topic of the paper, is described in more detail.
Options for the Destruction of Chemical Weapons and Management of the Associated Risks
Authors: MANLEY RON G.
Published: November 2006

Abstract: The destruction of chemical weapons is a hazardous operation. The degree of hazard posed, however, is not uniform and is dependent on the specific chemical agent and the configuration of the weapon or bulk storage vessel in which it is contained. For example, a highly volatile nerve agent in an explosively configured munition, such as a rocket, poses a very different hazard from that of a bulk storage container of viscous mustard gas. Equally the handling of recovered, often highly corroded, World War (WW)I or WWII chemical munitions will pose a very different hazard from that associated with dealing with modern chemical weapons stored under the appropriate conditions. Over the years, a number of technologies have been developed for the destruction of chemical weapons. Each has its advantages and disadvantages. None of them provide a universal solution to the problem. When assessing options for the destruction of these weapons and the management of the associated risks, therefore, it is important to give due consideration and weight to these differences. To ensure that the destruction technology selected takes due account of them and that the resulting overall risk assessment accurately reflects the actual risks involved.
Occupational Kidney Cancer
Authors: BRAUTBAR NACHMAN , WU MICHAEL P. , GABEL ELION , REGEV LEE
Published: November 2006

Abstract:  We report seven cases of renal cell carcinoma in workers diagnosed with occupational exposure via skin contact and inhalation to industrial solvents containing benzene. The clinical significance of these cases are: (a) all seven patients diagnosed with kidney cancer were seen by private physicians who missed addressing occupational history to industrial solvents; (b) emphasize the importance of taking an in‐depth history including occupational history in any patient presented to the clinician, especially like in these cases, kidney cancer; and (c) demonstrate the importance of educating workers. We believe that there exist more patients with renal cancer whose diagnosis has been rendered “idiopathic” due to the lack of detailed occupational, environmental, personal, and family history.
Evaluation of Exposure to PAHs in Asphalt Workers by Environmental and Biological Monitoring
Authors: CAMPO LAURA , BURATTI MARINA , FUSTINONI SILVIA , CIRLA PIERO E. , MARTINOTTI IRENE , LONGHI OMAR , CAVALLO DOMENICO , FOÀ VITO
Published: November 2006

Abstract:  In the present article we assessed exposure to polycyclic aromatic hydrocarbons (PAHs) in Italian asphalt workers (AW, n= 100), exposed to bitumen fumes and diesel exhausts, and in roadside construction workers (CW, n= 47), exposed to diesel exhausts, by means of environmental and biological monitoring. 1‐Hydroxypyrene (OH‐Py) was determined in urine spot samples collected, respectively, after 2 days of vacation (baseline), before, and at the end of the monitored work shift, in the second part of the workweek. Median airborne levels during the work shift of 15 PAHs (both vapor and particulate phases), from naphthalene (NAP) to indeno(1,2,3‐cd)pyrene, ranged from below 0.03 to 426 ng/m3. Median excretion values of OH‐Py in baseline, before‐ and end‐shift samples were 228, 402, and 690 ng/L for AW and 260, 304, and 378 ng/L for CW. Lower values were found in nonsmokers compared to smokers (e.g., in AW 565 and 781 versus 252 and 506 ng/L in before‐shift and end‐shift samples, respectively). In all subjects a weak correlation between personal exposure to the sum of airborne 15 PAHs and OH‐Py was observed (r= 0.30). The results of this article show that AW experienced a moderate occupational exposure to airborne PAHs, resulting in a significant increase of urinary OH‐Py during the workday and the workweek. The contribution of working activities to internal dose was in the same order of magnitude of the contribution of cigarette smoking.
Identification of Carcinogenic Agents and Primary Prevention of Cancer
Authors: TOMATIS LORENZO
Published: November 2006

Abstract: 
During the annual Ramazzini Days, the Mayor of Carpi confers the Ramazzini Award on scientists deemed by the Collegium Ramazzini to have made outstanding contributions to furthering the aims of Bernardino Ramazzini in safeguarding public health. Dr. Lorenzo Tomatis was the Ramazzini Award recipient in 2005, and the presentation of the award was a highlight of the Symposium. The Ramazzini Lecture given by Dr. Tomatis follows.
Pesticides and Adult Respiratory Outcomes in the Agricultural Health Study
Authors: HOPPIN JANE A. , UMBACH DAVID M. , LONDON STEPHANIE J. , LYNCH CHARLES F. , ALAVANJA MICHAEL C.R. , SANDLER DALE P.
Published: November 2006

Abstract:  In the 1700s, Bernardino Ramazzini was among the first to describe respiratory disease among agricultural workers. Since then, farmers continue to have higher rates of respiratory illnesses, even as changes occur in occupational and environmental exposures on farms. While grain and animal exposures have been well studied for their role in agricultural lung diseases, pesticide exposures have not. Using the Agricultural Health Study, a prospective cohort study of ∼89,000 licensed pesticide applicators and their spouses in Iowa and North Carolina, we are currently assessing the association of pesticides with respiratory outcomes, including wheeze, adult asthma, farmer's lung, and chronic bronchitis. At enrollment (1993–1997), 19% of farmers and 22% of commercial pesticide applicators reported wheeze in the previous year. Using logistic regression models adjusted for age, state, smoking status, and body mass index, we evaluated the association of 40 individual pesticides with wheeze within these two groups separately. In both groups, we observed strong evidence of an association of organophosphates with wheeze. For farmers, the organophosphates chlorpyrifos, malathion, and parathion were positively associated with wheeze; for the commercial applicators, the organophosphates chlorpyrifos, dichlorvos, and phorate were positively associated with wheeze. Chlorpyrifos was strongly associated with wheeze in a dose‐dependent manner in both groups; use of chlorpyrifos for at least 20 days per year had an odds ratio of 1.48 (95% confidence interval [CI]= 1.00–2.19) for farmers and 1.96 (95% CI = 1.05–3.66) for commercial applicators. Our wheeze results are consistent with recent animal models that support a role for organophosphates and respiratory outcomes.
Frequency and Quality of Radiation Monitoring of Construction Workers at Two Gaseous Diffusion Plants
Authors: BINGHAM EULA , RINGEN KNUT , DEMENT JOHN , CAMERON WILFRID , McGOWAN WILLIAM , WELCH LAURA , QUINN PATRICIA
Published: November 2006

Abstract:  Construction workers were and are considered temporary workers at many construction sites. Since World War II, large numbers of construction workers were employed at U.S. Department of Energy nuclear weapons sites for periods ranging from a few days to over 30 years. These workers performed tasks during new construction and maintenance, repair, renovation, and demolition of existing facilities. Such tasks may involve emergency situations, and may entail opportunities for significant radiation exposures. This paper provides data from interviews with more than 750 construction workers at two gaseous diffusion plants (GDPs) at Paducah, Kentucky, and Portsmouth, Ohio regarding radiation monitoring practices. The aim was to determine the extent to which workers believed they were monitored during tasks involving potential radiation exposures. The adequacy of monitoring practices is important for two reasons: (a) Protecting workers from exposures: Construction workers were employed by sub‐contractors, and may frequently been excluded from safety and health programs provided to permanent employees; and (b) Supporting claims for compensation: The Energy Employees Occupational Illness Compensation Program Act (EEOICPA) requires dose reconstruction of radiation exposures for most workers who file a claim regarding cancer. The use of monitoring data for radiation to qualify a worker means that there should be valid and complete monitoring during the work time at the various nuclear plants or workers may be unfairly denied compensation. The worker interviews from Paducah and Portsmouth were considered especially useful because these sites were designated as Special Exposure Cohorts (SECs) and the workers did not have to have a dose reconstruction to qualify for compensation for most cancers. Therefore, their responses were less likely to be affected by compensation concerns. Interview questions included asking for information regarding whether monitoring was performed, how often, and the maintenance (calibration) of monitoring equipment (devices).
Low‐Dose Risk, Hormesis, Analogical and Logical Thinking
Authors: ZAPPONI GIOVANNI A. , MARCELLO IDA
Published: November 2006

Abstract:  The hormesis theory proposes the low‐dose beneficial and high‐dose detrimental pattern, existing for specific conditions, as a “general default assumption” for toxicology and carcinogenicity. Crump and Kitchin and Drane underline that in a post hoc retrospective scientific literature searching for hormetic dose–response patterns, the consideration of the whole available relevant studies is necessary and, for statistical testing purposes, for instance at a 0.05 standard level, a P value obtained from 1 − (1 −P)n= 0.05 (i.e., P= 0.0005 for 100 examined cases) should be used (otherwise, by definition, 5 “positive” results are expected by chance over 100 cases). The hypothesis, based on some experimental data on rodents, by Calabrese and Baldwin, of an hormetic effect of 2,3,7,8‐TCDD at the 1–10 ng/kgbw/day dose, of Na‐saccharine in the ≤ 1% of diet exposure range, of Cadmium Chloride in the 0–5 μmol/kg dose range, single injection, and of neutrons in the 0‐ to 2‐rad dose range, are not confirmed, and, rather, are contradicted, when the whole relevant data presented by international and national agencies are considered. As far as the radiation risk is in particular concerned, a recently published epidemiological study on more than 400,000 nuclear plant workers, co‐ordinated by the IARC has indicated a small, but significant risk, at the current exposure limits, and possibly below them. Therefore, the hormesis theory‐based criticism of current radiation protection criteria, assumed to be excessively conservative, is not justified. Also not justified is the assumption that “by dismissing hormesis, regulatory agencies such as U.S. EPA deny the public the opportunity for optimal health and avoidance of diseases;” rather, the contrary is here considered true. Analogical considerations are not necessarily logical ones and the single result should be considered in its whole context.
Children's Environment and Health in Latin America
Authors: HARARI RAUL , HARARI HOMERO
Published: November 2006

Abstract:  Environmental health problems of children in Latin America and Ecuador are complex due to the close relationship that exists between social and environmental factors. Extended poverty and basic problems, such as the lack of drinking water and sanitation, are common. Infectious diseases are the greatest cause of morbidity and mortality among children. Development in industry and the introduction of chemical substances in agriculture add new risks including pesticide use, heavy metal exposure, and air pollution. Major problems can be divided into (a) lack of basic infrastructure, (b) poor living conditions, (c) specific environmental problems, and (d) child labor. Reproductive health disorders are frequent in developing countries like Ecuador.
Issues related to children's health should consider new approaches, creative methodologies, and the search for independent predictors to separate environmental from social problems. Only with knowledge of the specific contribution of each factor, can it be possible to develop a strategy for prevention.
The Cdi/TESK1 kinase is required for Sevenless signaling and epithelial organization in theDrosophilaeye
Authors: Sesé Marta , Corominas Montserrat , Stocker Hugo , Heino Tapio I. , Hafen Ernst , Serras Florenci
Published: November 2006

How cellular behaviors such as cell-to-cell communication, epithelial organization and cell shape reorganization are coordinated during development is poorly understood. The developing Drosophila eye offers an ideal model system to study these processes. Localized actin polymerization is required to constrict the apical surface of epithelial cells of the eye imaginal disc to maintain the refined arrangement of the developing ommatidia. The identity of each photoreceptor cell within the epithelium is determined by cell-to-cell contacts involving signal transduction events. The R7 photoreceptor cell requires the activity of the Sevenless RTK to adopt a proper cell fate. We performed an EP screen for negative regulators of this inductive process, and we identified the serine/threonine kinase Center divider (cdi) as a suppressor of the phenotype caused by an activated Sevenless receptor. Cdi is homologous to the human testis-specific kinase 1 (TESK1), a member of the LIM kinases involved in cytoskeleton control through ADF/cofilin phosphorylation. We have analyzed the effects of gain- and loss-of-function of cdi and found alterations in actin organization and in the adherens junctions proteins DE-cadherin and β-catenin, as well as in Sevenless apical localization. Interference with the function of the ADF/cofilin phosphatase Slingshot (ssh), which antagonizes Cdi, also results in a suppression of signaling triggered by the Sevenless RTK. Our results reveal a critical interplay between the localization of molecules involved in epithelial organization and signal transduction.
Efficacy with High-Dose Aripiprazole After Olanzapine-Related Metabolic Disturbances
Authors: Chavez Benjamin , Poveda Rene A
Published: November 2006

Objective:

To report a case in which a patient tolerated and responded to high-dose aripiprazole and lost weight after having been on olanzapine for several years; a secondary objective is to discuss the use of aripiprazole dosages at higher than those recommended in the product's labeling.

Case Summary:

A 57-year-old man with a 30 year history of schizophrenia had been taking olanzapine for 4 years, with the dosage titrated to 20 mg/day, to control the psychosis. After he had gained significant weight with olanzapine (the highest was 102.7 kg), his treatment was switched to aripiprazole. The patient required a high dose of aripiprazole (60 mg/day) to achieve full control of the psychiatric symptoms, and during aripiprazole therapy, he lost the weight he had gained while on olanzapine, weighing 85.9 kg within 7 months after the therapy switch.

Discussion:

Dosages of atypical antipsychotics higher than those recommended by the Food and Drug Administration are often used in clinical practice for refractory patients, despite the lack of evidence. The literature available on this subject is limited to small, double-blind trials; open-label trials; and case reports. Although certain patients may benefit from higher doses of atypical antipsychotics, the lack of evidence limits their use.

Conclusions:

High-dose aripiprazole (60 mg/day) was well tolerated and controlled this patient's symptoms effectively. In addition, he lost weight that was gained while being treated with olanzapine. High-dose aripiprazole may be beneficial and safe in refractory patients; however, large, double-blind, randomized clinical trials are needed.
Emerging Therapies in the Treatment of Clostridium difficile–Associated Disease
Authors: Jodlowski Tomasz Z , Oehler Richard , Kam Linda W , Melnychuk Igor
Published: November 2006

Objective:

To describe emergent therapies, such as rifaximin, nitazoxanide, intravenous immunoglobulin (IVIG), tinidazole, tolevamer, and the possible use of a vaccine, in Clostridium difficile–associated disease (CDAD), one of the most common causes of diarrhea in hospitalized adults in North America.

Data Sources:

A literature search was performed using MEDLINE (1996-October 2006), PubMed (1996–October 2006), abstracts from Infectious Diseases Society of America (September 2006) and International Conference on Antimicrobial Agents and Chemotherapy (September 2006), Internet (October 2006), Genzyme product Web site (October 2006), and Romark Laboratories Web site (October 2006) using the terms Clostridium difficile, rifaximin, nitazoxanide, intravenous immunoglobulin, tolevamer, vaccine, and tinidazole.

Study Selection and Data Extraction:

Data presented in this article were selected based on clinical relevance and power of the studies. In vivo and in vitro studies supporting the use of drugs available for treatment of refractory CDAD were reviewed. Some of the information on new and emerging modalities was also included, although there were limited published data available.

Data Synthesis:

Clinical trials evaluating the use of nitazoxanide and tolevamer for the treatment of CDAD have been published. Tinidazole use is based on structural similarities to metronidazole; however, clinical trials have not been conducted and the cost of this agent may be a limiting factor. The use of rifaximin and IVIG will require randomized clinical trials to establish their place in therapy. Limited information in the literature suggests that a vaccine may be effective for CDAD prevention.

Conclusions:

CDAD is a debilitating disease with increasing treatment failure rates and recurrences using standard therapies. Clinicians need to look at other options to expand the available treatment arsenal in addition to placing a greater emphasis on prevention.
Treatment Effects of Antidepressants in Patients with Post-Stroke Depression: A Meta-Analysis
Authors: Chen Yan , Guo Jeff J , Zhan Siyan , Patel Nick C
Published: November 2006

Background:

Appropriate treatment of post-stroke depression (PSD) is critically important, considering the negative impact of PSD. Data regarding the treatment efficacy of antidepressants in patients with PSD are conflicting, and the time-dependent effects of antidepressant treatment in this population are unknown.

Objective:

To systematically assess treatment effects of antidepressants in patients with PSD, incorporating data from recent studies.

Methods:

A meta-analysis of randomized placebo-controlled trials (RCTs) of antidepressants in patients with PSD was conducted, using published studies from 1984 to 2006. Outcome measures of antidepressant treatment included response rate, depression rating scale scores, recovery of neurologic impairments, and improvements in activities of daily living (ADLs) after stroke. The effect size was presented as rate difference (RD) and weighted mean difference for dichotomous outcomes and continuous outcomes, respectively. Pooled effect sizes were calculated by both fixed-effects and random-effects models.

Results:

A total of 1320 patients who met inclusion criteria were identified from 16 RCTs. The pooled response rates in the active and placebo groups were 65.18% (234/359) and 44.37% (138/311), respectively. The pooled RD was 0.23 (95% CI 0.03 to 0.43), indicating a significantly higher response rate in the active group compared with the placebo group. From baseline to endpoint, patients in the active group had significantly greater improvement in depressive symptoms compared with patients in the placebo group. Longer duration of treatment was positively correlated with the degree of improvement in depressive symptoms (Spearman's correlation, [ρ] = -0.93, p = 0.001). No consistent evidence was found for positive antidepressant effects on the recovery of neurologic impairments and improvements in ADLs.

Conclusions:

The results of this meta-analysis suggest that use of antidepressants among patients with a diagnosis of PSD is associated with improvement in depressive symptoms. Longer durations of antidepressant treatment may be associated with greater reductions in depressive symptoms.
Effect of Oral Corticosteroids on Chronic Warfarin Therapy
Authors: Hazlewood Kathleen A , Fugate Susan E , Harrison Donald L
Published: November 2006

Background:

A potential drug interaction exists between oral corticosteroids and warfarin, but there is limited documentation.

Objective:

To evaluate the potential drug interaction between oral corticosteroids and long-term warfarin therapy.

Methods:

A retrospective review was conducted of 387 medical records for active patients within an anticoagulation clinic. Inclusion criteria were stable anticoagulation therapy, short-term oral corticosteroid therapy, international normalized ratio (INR) recorded within 30 days prior to corticosteroid initiation (pre-INR), and INR recorded during corticosteroid therapy or within 14 days of discontinuation (post-INR). Patients were excluded if they had been started on any antibiotic or other drug with a probable interaction with warfarin at the same time as corticosteroid initiation. Thirty-two patient encounters met the predetermined inclusion and exclusion criteria. The primary outcome assessed was the difference between pre- and post-INR values. Secondary endpoints included bleeding events, emergency department (ED) visits, hospitalizations, and warfarin dose modifications.

Results:

The mean difference between pre- and post-INR values was 1.24 (95% CI 0.86 to 1.62). Ninety-seven percent of the 32 patient encounters resulted in a change in their post-INR value, and 62.5% of patients had supratherapeutic INR values at the post-corticosteroid assessment. The majority of patients assessed had an elevation of their INR following concomitant use of warfarin and corticosteroids. The INR change was observed at a mean ± SD of 6.7 ± 3.3 days following the first dose of corticosteroid. Overall, 16 patients (50%) required a modification of their anticoagulation therapy during or following corticosteroid therapy. Only one adverse event of minor epistaxis was reported, and no ED visits or hospitalizations occurred as a consequence of the drug combination.

Conclusions:

Use of oral corticosteroids in patients on long-term warfarin therapy may result in a clinically significant interaction, which requires close INR monitoring and possible warfarin dose reduction.
Isoperformance Curves in Applied Psychology
Authors: Jones Marshall B. , Kennedy Robert S.
Published: November 2006

Isoperformance is a technique for reading information out of a data-analytic model, comparable to expected mean square or omega squared analyses. It results in a trade-off function (an isoperformance curve) among the determinants of performance. The technique was developed primarily to generate trade-off functions between personnel aptitude and time in training or on the job. However, the technique is general and can be applied in any trade-off situation. In part, the purpose of this paper is to recall the antecedents of isoperformance in psychophysics and to recount the origins and development of the isoperformance readout. Its main purpose, however, is to present several examples of isoperformance curves in applied psychology and to make the case for their usefulness.
The Spacing Effect in Aircraft Recognition
Authors: Goettl Barry P.
Published: November 2006

Two theories of the spacing effect are compared in the context of aircraft recognition: working memory reconstruction and encoding variability. Participants (130 men and 110 women) viewed enhanced silhouettes of aircraft in one of four presentation schedules: massed once, massed repeated, distributed fixed, and distributed random. The two distributed schedules were designed to differ only on structural components. Thus the encoding variability theory predicts that the distributed-random schedule will be superior to the distributed-fixed schedule, whereas the working memory reconstruction theory predicts no difference between the two. Measures of recognition discriminability on novel view stimuli indicated that men, but not women, showed a recognition with the distributed-random schedule superior to that with all other schedules. Thus the men's data were consistent with the encoding variability hypothesis. The gender difference suggests the importance of processing style, familiarity, and motivation in aircraft recognition. These results have implications for aircraft recognition training and instructional design.
The Effect of a Priori Probability and Complexity on Decision Making in a Supervisory Control Task
Authors: Kerstholt Jose H. , Passenier Peter O. , Houttuin Kees , Schuffel Herke
Published: November 2006

In the present study we investigated how monitoring and fault management in a ship control task are affected by complexity and a priori probability of disturbances. Participants were required to supervise four independent shipping subsystems and to adjust the subsystems whenever deviations occurred. However, in order to apply the correct action, they first had to diagnose the cause of the deviation by requesting further subsystem information. Complexity and a priori probability were manipulated by varying the number of disturbances occurring simultaneously and the disturbance rates over subsystems. In general, the results indicate that the participants ignored the monitoring function when they were diagnosing a disturbance. Results also show evidence for “cognitive lockup”: Despite the possibility of stabilizing additional system faults and, consequently, increasing their time for diagnosis, participants tended not to interrupt an ongoing fault-finding process. Still, large individual differences were found in both the selected strategy and reasoning abilities.
Minimizing Fatigue during Repetitive Jobs: Optimal Work-Rest Schedules
Authors: Wood David D. , Fisher Donald L. , Andres Robert O.
Published: November 2006

Twenty women were asked to generate forces using a dynamometer that were consistent with one of three different work-rest schedules (a low-, medium-, and high-force schedule). Each work-rest schedule consisted of 6 identical blocks of 10 work-rest cycles. Each of the 10 work-rest cycles lasted 1 min. The first work-rest cycle in each block consisted of a 6--s maximal voluntary contraction and a 54--s rest. The remaining 9 work-rest cycles in each block consisted of a submaximal contraction and a rest period. The desired force of the submaximal contraction, the length of this contraction, and the duration of the rest period remained constant within schedules but varied across schedules. The amount of physiological work was kept constant among schedules. The fatigue that developed in the medium-force schedule was significantly lower than that developed in either the low- or high-force schedule. A model was developed that predicted the amount of fatiguable strength at the beginning and end of each contraction of a work-rest cycle. When fit to the results from the experiment, the model explained 94% of the variance. The model can be used to predict the work-rest schedule that minimizes fatigue in a given repetitive job, thereby potentially increasing productivity and reducing the incidence of cumulative trauma disorders.
Models of Shiftwork and Health: An Examination of the Influence of Stress on Shiftwork Theory
Authors: Taylor Emma , Briner Rob B. , Folkard Simon
Published: November 2006

This paper critically reviews models of shiftwork and health and provides a historical overview of changes in the conceptualization of the association between them. Models are hypothetical and conceptually broad, becoming more so as they move away from linear, chronobiological to multidirectional, psychological conceptualizations. We attribute this tendency to the use of stress frameworks to explain the relationship between shiftwork and health. We assess the usefulness of stress as an explanatory concept in terms of how it affects shiftwork research and practice and make recommendations for future practice and theory development.
Cross-Modal Processing in Early Visual and Auditory Cortices depends on Expected Statistical Relationship of Multisensory Information
Authors: Baier Bernhard , Kleinschmidt Andreas , Müller Notger G.
Published: November 2006

Previous studies have shown that processing information in one sensory modality can either be enhanced or attenuated by concurrent stimulation of another modality. Here, we reconcile these apparently contradictory results by showing that the sign of cross-modal interactions depends on whether the content of two modalities is associated or not. When concurrently presented auditory and visual stimuli are paired by chance, cue-induced preparatory neural activity is strongly enhanced in the task-relevant sensory system and suppressed in the irrelevant system. Conversely, when information in the two modalities is reliably associated, activity is enhanced in both systems regardless of which modality is task relevant. Our findings illustrate an ecologically optimal flexibility of the neural mechanisms that govern multisensory processing: facilitation occurs when integration is expected, and suppression occurs when distraction is expected. Because thalamic structures were more active when the senses needed to operate separately, we propose them to serve gatekeeper functions in early cross-modal interactions.
Stimulus Frequency Processing in Awake Rat Barrel Cortex
Authors: Melzer Peter , Sachdev Robert N. S. , Jenkinson Ned , Ebner Ford F.
Published: November 2006

In awake rats, we examined the relationship between neural spiking activity in primary somatic sensory cortex and the frequency of whisker stimulation. Neural responses were recorded extracellularly in barrel cortex while single whiskers were deflected with 0.5–18 air puffs per second (apps), a range that includes the whisk rates observed when rats explore their environment and discriminate surfaces with their whiskers. Twenty-nine neurons in layers III and IV were isolated in three rats (23 in barrel columns and 6 in septum columns). At ≤9 apps, cortical neurons responded with one to two spikes per stimulus, whereas at >9 apps, the response efficacy was reduced to only 0.2–0.4 spikes per stimulus. Several mechanisms are discussed that could account for the decrement in responsiveness. Despite this adaptation, neural spike rates increased in direct proportion with stimulus frequency when cast on logarithmic scales. At >9 apps, however, this relationship deteriorated in barrel columns in which the response approximately halved. In contrast, septum column cells continued to increase their spike rates linearly up to 18 apps, although they responded at lower magnitude than the barrel column cells. Our findings suggest that septum column neurons are potential candidates to encode stimulus frequency using spike rate across the entire frequency range relevant to rats' whisking behavior.
Deletion ofKv4.2Gene Eliminates Dendritic A-Type K+Current and Enhances Induction of Long-Term Potentiation in Hippocampal CA1 Pyramidal Neurons
Authors: Chen Xixi , Yuan Li-Lian , Zhao Cuiping , Birnbaum Shari G. , Frick Andreas , Jung Wonil E. , Schwarz Thomas L. , Sweatt J. David , Johnston Daniel
Published: November 2006

Dendritic, backpropagating action potentials (bAPs) facilitate the induction of Hebbian long-term potentiation (LTP). Although bAPs in distal dendrites of hippocampal CA1 pyramidal neurons are attenuated when propagating from the soma, their amplitude can be increased greatly via downregulation of dendritic A-type K+currents. The channels that underlie these currents thus may represent a key regulatory component of the signaling pathways that lead to synaptic plasticity. We directly tested this hypothesis by usingKv4.2knock-out mice. Deletion of theKv4.2gene and a loss of Kv4.2 protein resulted in a specific and near-complete elimination of A-type K+currents from the apical dendrites of CA1 pyramidal neurons. The absence of dendriticKv4.2-encoded A-type K+currents led to an increase of bAP amplitude and an increase of concurrent Ca2+influx. Furthermore, CA1 pyramidal neurons lacking dendritic A-type K+currents fromKv4.2knock-out mice exhibited a lower threshold than those of wild-type littermates for LTP induction with the use of a theta burst pairing protocol. LTP triggered with the use of a saturating protocol, on the other hand, remained indistinguishable betweenKv4.2knock-out and wild-type neurons. Our results support the hypothesis that dendritic A-type K+channels, composed of Kv4.2 subunits, regulate action potential backpropagation and the induction of specific forms of synaptic plasticity.
Unanticipated Region- and Cell-Specific Downregulation of Individual KChIP Auxiliary Subunit Isotypes in Kv4.2 Knock-Out Mouse Brain
Authors: Menegola Milena , Trimmer James S.
Published: November 2006

Kv4 family voltage-gated potassium channel α subunits and Kv channel-interacting protein (KChIP) and dipeptidyl aminopeptidase-like protein subunits comprise somatodendritic A-type channels in mammalian neurons. Recently, a mouse was generated with a targeted deletion of Kv4.2, a Kv4 α subunit expressed in many but not all mammalian brain neurons.Kv4.2−/−mice are grossly indistinguishable from wild-type (WT) littermates. Here we used immunohistochemistry to analyze expression of component Kv4 and KChIP subunits of A-type channels in WT andKv4.2−/−brains. We found that the expression level, and cellular and subcellular distribution of the other prominent brain Kv4 family member Kv4.3, was indistinguishable between WT andKv4.2−/−samples. However, we found unanticipated regional and cell-specific decreases in expression of KChIPs. The degree of altered expression of individual KChIP isoforms in different regions and neurons precisely follows the level of Kv4.2 normally found at those sites and presumably their extent of association of these KChIPs with Kv4.2. The dramatic effects of Kv4.2 deletion on KChIP expression suggest that, in addition to previously characterized effects of KChIPs on the functional properties, trafficking, and turnover rate of Kv4 channels, Kv4:KChIP association may confer reciprocal Kv4.2-dependent effects on KChIPs. The impact of Kv4.2 deletion on KChIP expression also supports the major role of KChIPs as auxiliary subunits of Kv4 channels.
The Rewards of Nicotine: Regulation by Tissue Plasminogen Activator–Plasmin System through Protease Activated Receptor-1
Authors: Nagai Taku , Ito Mina , Nakamichi Noritaka , Mizoguchi Hiroyuki , Kamei Hiroyuki , Fukakusa Ayumi , Nabeshima Toshitaka , Takuma Kazuhiro , Yamada Kiyofumi
Published: November 2006

Nicotine, a primary component of tobacco, is one of the most abused drugs worldwide. Approximately four million people die each year because of diseases associated with tobacco smoking. Mesolimbic dopaminergic neurons mediate the rewarding effects of abused drugs, including nicotine. Here we show that the tissue plasminogen activator (tPA)–plasmin system regulates nicotine-induced reward and dopamine release by activating protease activated receptor-1 (PAR1).In vivomicrodialysis revealed that microinjection of either tPA or plasmin into the nucleus accumbens (NAc) significantly potentiated whereas plasminogen activator inhibitor-1 reduced the nicotine-induced dopamine release in the NAc in a dose-dependent manner. Nicotine-induced dopamine release was markedly diminished in tPA-deficient (tPA−/−)mice, and the defect of dopamine release intPA−/−mice was restored by microinjection of either exogenous tPA or plasmin into the NAc. Nicotine increased tPA protein levels and promoted the release of tPA into the extracellular space in the NAc. Immunohistochemistry revealed that PAR1 immunoreactivity was localized to the nerve terminals positive for tyrosine hydroxylase in the NAc. Furthermore, we demonstrated that plasmin activated PAR1 and that nicotine-induced place preference and dopamine release were diminished in PAR1-deficient (PAR1−/−) mice. Targeting the tPA–plasmin–PAR1 system would provide new therapeutic approaches to the treatment of nicotine dependence.
A Circadian Clock in the Olfactory Bulb Controls Olfactory Responsivity
Authors: Granados-Fuentes Daniel , Tseng Alan , Herzog Erik D.
Published: November 2006

Recently, it has been shown that multiple mammalian cell types express daily rhythmsin vitro. Although the suprachiasmatic nucleus (SCN) of the hypothalamus is known to regulate a wide range of circadian behaviors, the role for intrinsic rhythmicity in other tissues is unknown. We tested whether the main olfactory bulb (OB) of mice mediates daily changes in olfaction. We found circadian rhythms in cedar oil-induced c-Fos, a protein marker of cellular excitation, in the mitral and granular layers of the OB and in the piriform cortex (PC). These oscillations persisted in constant darkness with a fourfold change in amplitude and a peak ∼4 h after the onset of daily locomotor activity. Electrolytic lesions of the SCN abolished circadian locomotor rhythms, but not odor-induced c-Fos rhythms in the OB or PC. Furthermore, removal of the OB abolished spontaneous circadian cycling of c-Fos in the PC, shortened the free-running period of locomotor rhythms, and accelerated re-entrainment after a 6 h advance and slowed re-entrainment after a 6 h delay in the light schedule. OB ablation or odorant altered the amplitude of c-Fos rhythms in the SCN and ablation of one OB abolished c-Fos rhythms in the ipsilateral PC, but not in the contralateral OB and PC. We conclude that the OB comprises a master circadian pacemaker, which enhances olfactory responsivity each night, drives rhythms in the PC, and interacts with the SCN to coordinate other daily behaviors.
Somatodendritic Kv7/KCNQ/M Channels Control Interspike Interval in Hippocampal Interneurons
Authors: Lawrence J. Josh , Saraga Fernanda , Churchill Joseph F. , Statland Jeffrey M. , Travis Katherine E. , Skinner Frances K. , McBain Chris J.
Published: November 2006

The M-current (IM), comprised of Kv7 channels, is a voltage-activated K+conductance that plays a key role in the control of cell excitability. In hippocampal principal cells,IMcontrols action potential (AP) accommodation and contributes to the medium-duration afterhyperpolarization, but the role ofIMin control of interneuron excitability remains unclear. Here, we investigatedIMin hippocampal stratum oriens (SO) interneurons, both from wild-type and transgenic mice in which green fluorescent protein (GFP) was expressed in somatostatin-containing interneurons. Somatodendritic expression of Kv7.2 or Kv7.3 subunits was colocalized in a subset of GFP+ SO interneurons, corresponding to oriens-lacunosum moleculare (O-LM) cells. Under voltage clamp (VC) conditions at −30 mV, the Kv7 channel antagonists linopirdine/XE-991 abolished theIMamplitude present during relaxation from −30 to −50 mV and reduced the holding current (Ihold). In addition, 0.5 mmtetraethylammonium reducedIM, suggesting thatIMwas composed of Kv7.2-containing channels. In contrast, the Kv7 channel opener retigabine increasedIMamplitude andIhold. When strongly depolarized in VC, the linopirdine-sensitive outward current activated rapidly and comprised up to 20% of the total current. In current-clamp recordings from GFP+ SO cells, linopirdine induced depolarization and increased AP frequency, whereas retigabine induced hyperpolarization and arrested firing. In multicompartment O-LM interneuron models that incorporatedIM, somatodendritic placement of Kv7 channels best reproduced experimentally measuredIM. The models suggest that Kv3- and Kv7-mediated channels both rapidly activate during single APs; however, Kv3 channels control rapid repolarization of the AP, whereas Kv7 channels primarily control the interspike interval.
Chronic Pain and the Emotional Brain: Specific Brain Activity Associated with Spontaneous Fluctuations of Intensity of Chronic Back Pain
Authors: Baliki Marwan N. , Chialvo Dante R. , Geha Paul Y. , Levy Robert M. , Harden R. Norman , Parrish Todd B. , Apkarian A. Vania
Published: November 2006

Living with unrelenting pain (chronic pain) is maladaptive and is thought to be associated with physiological and psychological modifications, yet there is a lack of knowledge regarding brain elements involved in such conditions. Here, we identify brain regions involved in spontaneous pain of chronic back pain (CBP) in two separate groups of patients (n= 13 andn= 11), and contrast brain activity between spontaneous pain and thermal pain (CBP and healthy subjects,n= 11 each). Continuous ratings of fluctuations of spontaneous pain during functional magnetic resonance imaging were separated into two components: high sustained pain and increasing pain. Sustained high pain of CBP resulted in increased activity in the medial prefrontal cortex (mPFC; including rostral anterior cingulate). This mPFC activity was strongly related to intensity of CBP, and the region is known to be involved in negative emotions, response conflict, and detection of unfavorable outcomes, especially in relation to the self. In contrast, the increasing phase of CBP transiently activated brain regions commonly observed for acute pain, best exemplified by the insula, which tightly reflected duration of CBP. When spontaneous pain of CBP was contrasted to thermal stimulation, we observe a double-dissociation between mPFC and insula with the former correlating only to intensity of spontaneous pain and the latter correlating only to pain intensity for thermal stimulation. These findings suggest that subjective spontaneous pain of CBP involves specific spatiotemporal neuronal mechanisms, distinct from those observed for acute experimental pain, implicating a salient role for emotional brain concerning the self.
Distinct Populations of Spinal Cord Lamina II Interneurons Expressing G-Protein-Gated Potassium Channels
Authors: Marker Cheryl L. , Luján Rafael , Colón José , Wickman Kevin
Published: November 2006

Noxious stimuli are sensed and carried to the spinal cord dorsal horn by Aδ and C primary afferent fibers. Some of this input is relayed directly to supraspinal sites by projection neurons, whereas much of the input impinges on a heterogeneous population of interneurons in lamina II. Previously, we demonstrated that G-protein-gated inwardly rectifying potassium (GIRK) channels are expressed in lamina II of the mouse spinal cord and that pharmacologic ablation of spinal GIRK channels selectively blunts the analgesic effect of high but not lower doses of intrathecal μ-opioid receptor (MOR) agonists. Here, we report that GIRK channels formed by GIRK1 and GIRK2 subunits are found in two large populations of lamina II excitatory interneurons. One population displays relatively large apparent whole-cell capacitances and prominent GIRK-dependent current responses to the MOR agonist [D-Ala2,N-MePhe4,Gly-ol5] -enkephalin (DAMGO). A second population shows smaller apparent capacitance values and a GIRK-dependent response to the GABABreceptor agonist baclofen, but not DAMGO. Ultrastructural analysis revealed that GIRK subunits preferentially label type I synaptic glomeruli, suggesting that GIRK-containing lamina II interneurons receive prominent input from C fibers, while receiving little input from Aδ fibers. Thus, excitatory interneurons in lamina II of the mouse spinal cord can be subdivided into different populations based on the neurotransmitter system coupled to GIRK channels. This important distinction will afford a unique opportunity to characterize spinal nociceptive circuitry with defined physiological significance.
Salinity Tolerance and Salt Gland Excretion Efficiency of Bermudagrass Turf Cultivars
Authors: Marcum K. B. , Pessarakli M.
Published: November 2006

Need for salt tolerant turfgrasses is increasing due to government mandates requiring use of low quality, secondary water sources for turfgrass irrigation. Objectives of this study were to determine the range in salinity tolerance among modern Cynodon spp. (bermudagrass) turf cultivars, determine if leaf salt gland excretion is an important salinity tolerance mechanism in bermudagrass, and if salinity tolerance is associated with the rate, or efficiency of leaf salt gland excretion. Salinity responses of thirty five bermudagrass turf cultivars [Cynodon dactylon (L.) Pers, and C. dactylon × Cynodon transvaalensis (Burtt‐Davey)] were determined by exposing plants to five salinity levels (0, 15, 30, 45, and 60 dS m−1). Salinity tolerance among cultivars was determined by shoot dry weight reduction relative to control plants and by percent green leaf canopy area (GLCA). Salinity resulting in 50% reduction in shoot dry weight (SW50) ranged from 26 to 40 dS m−1, indicating a wide range in salinity tolerance within this genus. Salt glands were present on both abaxial and adaxial leaf surfaces of all cultivars. Salinity tolerance was negatively correlated with leaf tissue Na+ concentration and positively correlated with leaf salt gland Na+ excretion rate, indicating that salinity tolerance in bermudagrasses is associated with shoot saline ion exclusion and to leaf salt gland excretion efficiency.