bluuebunny/crossref_metadata_2025 huggingface dataset:
Degradation kinetics of ptaquiloside in soil and soil solution
Authors: Ovesen Rikke Gleerup , Rasmussen Lars Holm , Hansen Hans Christian Bruun
Published: January 2008

Ptaquiloside (PTA) is a carcinogenic norsesquiterpene glycoside produced in bracken (Pteridium aquilinum (L.) Kuhn), a widespread, aggressive weed. Transfer of PTA to soil and soil solution eventually may contaminate groundwater and surface water. Degradation rates of PTA were quantified in soil and soil solutions in sandy and clayey soils subjected to high natural PTA loads from bracken stands. Degradation kinetics in moist soil could be fitted with the sum of a fast and a slow first-order reaction; the fast reaction contributed 20 to 50% of the total degradation of PTA. The fast reaction was similar in all horizons, with the rate constant k1F ranging between 0.23 and 1.5/h. The slow degradation, with the rate constant k1S ranging between 0.00067 and 0.029/h, was more than twice as fast in topsoils compared to subsoils, which is attributable to higher microbial activity in topsoils. Experiments with sterile controls confirmed that nonmicrobial degradation processes constituted more than 90% of the fast degradation and 50% of the slow degradation. The lower nonmicrobial degradation rate observed in the clayey compared with the sandy soil is attributed to a stabilizing effect of PTA by clay silicates. Ptaquiloside appeared to be stable in all soil solutions, in which no degradation was observed within a period of 28 d, in strong contrast to previous studies of hydrolysis rates in artificial aqueous electrolytes. The present study predicts that the risk of PTA leaching is controlled mainly by the residence time of pore water in soil, soil microbial activity, and content of organic matter and clay silicates.
Potential for 4-n-nonylphenol biodegradation in stream sediments
Authors: Bradley Paul M , Barber Larry B , Kolpin Dana W , McMahon Peter B , Chapelle Francis H
Published: January 2008

The potential for in situ biodegradation of 4-nonylphenol (4-NP) was investigated in three hydrologically distinct streams impacted by wastewater treatment plants (WWTPs) in the United States. Microcosms were prepared with sediments from each site and amended with [U-ring-14C]4-n-nonylphenol (4-n-NP) as a model test substrate. Microcosms prepared with sediment collected upstream of the WWTP outfalls and incubated under oxic conditions showed rapid and complete mineralization of [U-ring-14C]4-n-NP to 14CO2 in all three systems. In contrast, no mineralization of [U-ring-14C]4-n-NP was observed in these sediments under anoxic (methanogenic) conditions. The initial linear rate of [U-ring-14C]4-n-NP mineralization in sediments from upstream and downstream of the respective WWTP outfalls was inversely correlated with the biochemical oxygen demand (BOD) of the streambed sediments. These results suggest that the net supply of dissolved oxygen to streambed sediments is a key determinant of the rate and extent of 4-NP biodegradation in stream systems. In the stream systems considered by the present study, dissolved oxygen concentrations in the overlying water column (8–10 mg/L) and in the bed sediment pore water (1–3 mg/L at a depth of 10 cm below the sediment–water interface) were consistent with active in situ 4-NP biodegradation. These results suggest WWTP procedures that maximize the delivery of dissolved oxygen while minimizing the release of BOD to stream receptors favor efficient biodegradation of 4-NP contaminants in wastewater-impacted stream environments.
Effects of a Veterinary Student Leadership Program on Measures of Stress and Academic Performance
Authors: Moore Dale A. , Truscott Marla L. , Clair Lisa St. , Klingborg Donald J.
Published: January 2008

Assuming leadership roles in veterinary student governance or club activities could be considered an added stressor for students because of the impact on time available for personal and academic activities. The study reported here evaluated the effects of participation in a leadership program and leadership activity across two classes of veterinary students on measures of stress, using the Derogatis Stress Profile (DSP), and on veterinary school academic performance, measured as annual grade-point average (GPA) over a three-year period. Program participants and their classmates completed the DSP three times across the first three years of veterinary school. On average, participating students reported self-declared stress levels that were higher and measured DSP stress levels that were lower than those of the general population. Students were more likely to assume elected or appointed leadership roles while in their first three years of the veterinary degree program if they participated in the optional leadership program and demonstrated lower stress in several dimensions. Some increased stress, as measured in some of the DSP stress dimensions, had a small but statistically significant influence on professional school GPA. The study determined that the most important predictors of students’ cumulative GPA across the three-year period were the GPA from the last 45 credits of pre-veterinary coursework and their quantitative GRE scores. The results of the study indicate that neither participation in the leadership program nor taking on leadership roles within veterinary school appeared to influence veterinary school academic performance or to increase stress.
Involving Practitioners in Continuing Education Needs Assessment: Use of the Nominal Group Technique
Authors: Moore Dale A. , Klingborg Donald J.
Published: January 2008

The nominal group technique (NGT) is described. An example of this method is provided. The goal was to identify clinical cases that could be used in a practitioner self-assessment tool. Practitioners in three groups were asked to keep a journal about cases they saw in the two weeks prior to their group discussion, individually provide case ideas within the group, and prioritize the cases individually. The groups provided over 192 case descriptions that can be used in a self-assessment tool for small animal practitioners. The NGT is a valuable tool that can identify and prioritize issues.
Veterinary Students' Views on Animal Patients and Human Clients, Using Q-Methodology
Authors: de Graaf Gjalt
Published: January 2008

Veterinarians serve two masters: animal patients and human clients. Both animal patients and human clients have legitimate interests, and conflicting moral claims may flow from these interests. Earlier research concludes that veterinary students are very much aware of the complex and often paradoxical relationship they have and will have with animals. In this article the views of veterinary students about their anticipated relationship with animal patients and human clients are studied. The main part of the article describes discourses of first-year and fourth-year students about their (future) relationship with animals and their caretakers, for which Q-methodology is used. At the end of the article, the discourses are related to the students’ gender and their workplace preferences.
Errors in Radiographic Interpretation Made by Veterinary Students
Authors: Lamb C.R. , Pfeiffer D.U. , Mantis P.
Published: January 2008

As a means of identifying student weaknesses in radiographic interpretation that could be used as foci for teaching, a cohort of 96 students joining the final-year radiology rotation were randomly allocated to one of three radiographic interpretation quizzes, each based on radiographs of small-animal patients together with the signalment and a brief, relevant history. Students’ quiz scores were analyzed by multiple logistic regression, using an outcome variable with the score for each item as numerator and maximum possible mark as denominator. Students’ median quiz score was 49% of the maximum (range 23–80%). Students were more likely to gain a mark for items based on abnormal radiographs than for those based on normal radiographs (odds ratio 3.4, p < 0.001). Skeletal radiographs were associated with lower scores (OR 0.75, p = 0.03). The fewest marks were awarded for interpretation of a radiograph of a normal canine stifle and interpretation of a radiograph of a normal canine pelvis; these items were misinterpreted as abnormal by 86% and 80% of the students, respectively. Students’ tendency to over-interpret normal radiographs may reflect a lack of knowledge of radiographic anatomy or an unrealistically high expectation that the radiographs are abnormal.
Implementing Change in Health Professions Education: Stakeholder Analysis and Coalition Building
Authors: Baum Karyn D. , Resnik Cheryl D. , Wu Jennifer J. , Roey Steven C.
Published: January 2008

The challenges facing the health sciences education fields are more evident than ever. Professional health sciences educators have more demands on their time, more knowledge to manage, and ever-dwindling sources of financial support. Change is often necessary to either keep programs viable or meet the changing needs of health education. This article outlines a simple but powerful three-step tool to help educators become successful agents of change. Through the application of principles well known and widely used in business management, readers will understand the concepts behind stakeholder analysis and coalition building. These concepts are part of a powerful tool kit that educators need in order to become effective agents of change in the health sciences environment. Using the example of curriculum change at a school of veterinary medicine, we will outline the three steps involved, from stakeholder identification and analysis to building and managing coalitions for change.
Admissions Test for the Degree Course in Veterinary Medicine in Italy, 2005
Authors: Corradi Attilio , Bottarelli Ezio , Bertoli Barbara , Flammini Cesidio F.
Published: January 2008

In Italy, access to the degree course in veterinary medicine is regulated each academic year by a government decree that sets the maximum student intake number for each of the 14 existing faculties. Candidates are selected by means of a multiple-choice test on the following subjects: logic and general knowledge, biology, chemistry, physics, and mathematics. Data for the 2005/2006 academic year are presented here. Overall, 4,495 candidates took the test and 1,415 (31.5%) qualified. The questions relating to physics and mathematics were more difficult than those in other subjects (p < 0.001). Logic and general knowledge was the subject in which candidates’ knowledge was best. Separate data for each of the 14 Italian faculties are presented, along with the cut-off score for admission. In addition, a “difficulty admission index” has been calculated for each faculty centre.
Instructional Design for Online Course Development
Authors: Cooperman Larry
Published: January 2008

There is a big difference between preparing to teach in the classroom and preparing to teach online. The classroom environment is typically marked by a level of spontaneity in instruction; beyond the preparation—the course syllabus and the PowerPoint slides, for example—the delivery of the course is largely altered by both the dynamics of the class and the impromptu decisions of the professor. Mediating this dynamic is the nature of the subject matter itself—teaching a course in computer programming varies dramatically from a course in sociology. The goal of this article is to explain the uses and misuses of instructional design, its foundational frameworks, and its implications for online education.
Support Services for Students and Faculty
Authors: Kendall Janet Ross
Published: January 2008

Distance learning is hardly a recent phenomenon. The recent growth of distance-education courses and programs, particularly those offered online, has been dramatic. Students enrolled in distance-education courses deserve the same quality and type of services that students taking courses on campus receive. The same is true of faculty teaching distance courses. Developing strong support services for both groups is an evolutionary process. This article discusses support services for both students and faculty involved in the rapidly expanding online distance-education landscape. Models for providing support to students and faculty are described, the development of these services is explained, and examples of support services are provided.
Effect of the Recently Established Admissions Procedure on Success in the First-Year Exams at the University of Veterinary Medicine Vienna, Austria
Authors: Breit Sabine M , Künzel Wolfgang
Published: January 2008

Rationale for this study—The purpose of this study was to compare the success during the first academic year of students who underwent an admissions procedure (class 2005) and students of the three previous classes (2002–2004), who did not undergo an admissions procedure but took their exams under the same curricular framework.

Methodology—Exam results of 802 students of the 2002–2004 classes were compared with those of 181 students from the 2005 class.

Results—Students of the 2005 class were more likely to pass all three exams given in the first academic year than students of the 2002–2004 classes (p < 0.001; OR = 3.2), and the quality of two of the three exams (indicated by individual scores) was also significantly better in 2005 than in the preceding classes (p < 0.001). In unselected classes, 25% to 31% of students showed no successful attempts to pass any of the three exams currently administered.

Conclusion—The implementation of an admissions procedure measuring, among other indicators, academic ability has significantly improved first-year exam performance. Incoming students presenting with higher scores on academic standards are more likely to complete their courses successfully.
Fracture Mechanics Analysis for Saw Cutting Requirements of Concrete Pavements
Authors: Gaedicke Cristian , Villalobos Salvador , Roesler Jeffery , Lange David
Published: January 2008

Concrete sawing operations are performed at predetermined locations within the first 24 h to prevent random cracking on jointed plain concrete pavements. In current construction procedures, the depth and timing of the saw are usually established by the contractor on the basis of experience. A study analyzed the effect of several concrete mixture proportions and constituents on the early-age fracture properties and their effect on saw cut timing and depth for concrete pavements with several slab geometries. Concrete pavement mixtures with different coarse aggregate size and cementitious content were evaluated to determine sensitivity of the measured fracture properties on saw cut model predictions. Finite element analysis was used to derive the geometric correction factors necessary to characterize the fracture properties of concrete based on the wedge splitting test configuration. A saw cut depth model previously proposed was modified to determine the timing and depth of notches on jointed plain concrete pavements. The theoretical analysis and practical example lead to the observation that if greater time is desired before saw cutting, the design should favor concrete materials with slower development of fracture properties. Thinner concrete pavements also require significantly deeper notch depth ratios relative to those of thicker slabs.
Midwest Guardrail System for Long-Span Culvert Applications
Authors: Bielenberg Robert W. , Faller Ronald K. , Sicking Dean L. , Rohde John R. , Reid John D.
Published: January 2008

Long-span guardrail systems have been recognized as an effective means of shielding low-fill culverts. These designs are popular because, in comparison with other systems that attach posts to the top of the culvert, they are able to shield the culvert safely while creating little additional construction effort and limiting the damage to the culvert and the need for repair. However, previous long-span designs were limited by the need to use long sections of nested guardrail to prevent rail rupture and by the need for large lateral offsets between the barrier and the culvert. The Midwest Guardrail System (MGS) long-span design eliminates those two shortcomings by applying the benefits of the MGS to a long-span design. The MGS long-span design increased vehicle capture and stability because of the increased rail height, limited the potential for pocketing and wheel snag through the use of controlled-release terminal posts adjacent to the unsupported span, and greatly increased the tensile capacity of the rail through the movement of splices away from the posts and the use of shallower post embedment. These features allowed the system to be developed without the use of a nested guardrail and with a minimal barrier offset that placed the back of the guardrail posts even with the front face of the culvert. Two full-scale crash tests were conducted with the MGS long-span design according to the requirements in NCHRP Report 350 for Test Level 3 Test Designation 3-11. Both tests were conducted with the heavier 2,270-kg pickup truck to generate higher rail loads and dynamic deflections. The MGS long-span design met all safety requirements of NCHRP Report 350. The ability of the guardrail with the MGS long-span design to perform safely without a nested rail and a minimal barrier offset makes this new barrier a functional and safe option for the protection of low-fill culverts.
Performance Evaluation of Low-Tension Three-Strand Cable Median Barriers
Authors: Marzougui Dhafer , Mohan Pradeep , Kan Cing Dao (Steve) , Opiela Kenneth
Published: January 2008

The primary purpose of longitudinal safety barriers, such as cable barriers, is to contain or redirect errant vehicles that depart the roadway and thereby keep them from entering opposing travel lanes or encountering terrain features and roadside objects that may cause severe impacts. In this study, finite element analysis, vehicle dynamics analysis, and full-scale crash testing were performed to study the effects of sloped terrain on the safety performance of cable median barriers. A detailed finite element model of a three-strand cable barrier was developed and validated against a previously conducted full-scale crash test. The full-scale crash test and simulation were set up for an impact of the cable barrier with a 2,000-kg (4,400-lb) pickup truck at an angle of 25° and an initial velocity of 100 km/h (62 mph). This setup is in accordance with NCHRP Report 350 guidelines for Test Level 3 safety performance. With this model, computer simulations were performed to assess the performance of the barrier under different impact scenarios and with different terrain profiles. Vehicle dynamics analyses were also conducted to compute the trajectory and dynamics of the vehicle as it crossed the sloped terrain and struck the cable median barrier. On completion of the computer simulation analyses, full-scale crash testing was performed to validate the results.
Facilitation of tree saplings by nurse plants: Microhabitat amelioration or protection against herbivores?
Authors: Gómez‐Aparicio Lorena , Zamora Regino , Castro Jorge , Hódar Jose A.
Published: January 2008

Question:Positive interactions are predicted to be common in communities developing under high physical stress or high herbivory pressure due to neighbour amelioration of limiting physical and consumer stresses, respectively. However, when both stress sources meet in the same community, the relative importance of the two facilitation mechanisms is poorly understood. We ask: What is the relative importance of abiotic vs. biotic mechanisms of facilitation of tree saplings by shrubs in Mediterranean mountain forests?

Location:Sierra Nevada, SE Spain (1800–1850 m a.s.l.)

Methods:Saplings of four tree taxa (Acer opalusssp.grana‐tense, Quercus ilex, Pinus nigra ssp. salzmaniiandP. sylvestrisvar.nevadensis) were planted following a 2 × 2 factorial design: two levels of herbivory (control and ungulate exclusion) and two microhabitats (under shrubs and in open areas). Sapling survival and growth were monitored for five years.

Results:Shrubs had positive effects on sapling survival both in control and ungulate excluded plots. This effect was species‐specific, with shrubs increasing the survival ofAcer opalusandQuercus ilexthree and twofold, respectively, but having a minor effect on thePinusspecies. Herbivory damage was also species‐specific, being much higher forAcer opalusthan for any other species. Shrubs did not protect saplings of any species against ungulates. Thus, allAcersaplings (the most damaged species) suffered herbivory outside the exclosures, which largely reduced sapling height.

Conclusions:Protection from abiotic stress (summer drought and winter frost) was much more relevant than protection from biotic stress (herbivory). However, we propose that the final balance between the two mechanisms can be expected to vary strongly between sites, depending on the relative magnitude of the different sources of stress and the intrinsic traits (e.g. palatability) of the species interacting.
Should genetic testing for BRCA1/2 be permitted for minors? Opinions of BRCA mutation carriers and their adult offspring
Authors: Bradbury Angela R. , Patrick‐Miller Linda , Pawlowski Kimberly , Ibe Comfort N. , Cummings Shelly A. , Olopade Olufunmilayo I. , Daugherty Christopher K.
Published: January 2008

Although professional guidelines recommend against testing minors for adult‐onset genetic conditions, the genetic testing of minors for BRCA1/2 alterations has been debated in the literature. To better understand the opinions of BRCA mutation carriers regarding the genetic testing of minors and the cognitive and affective processes underlying these opinions, we interviewed BRCA mutation carriers and their adult offspring who had learned of their parent's BRCA mutation. Semi‐structured interviews were conducted with 53 parents and 22 offspring. In response to a closed‐ended question, 52% (n = 39) of participants were opposed to the testing of minors. Responses to an open‐ended question indicate that many participants (24%, n = 18) feel that testing could be permitted for some minor offspring. Psychological risks and the insufficient maturity of minors were frequent concerns of participants opposed to testing minors. The potential to impact health behaviors was frequently cited as a reason to support the genetic testing of minors. These preliminary results suggest that many BRCA mutation carriers and their adult offspring have concerns about, or are opposed to the genetic testing of minors. However, a significant minority in our study would support testing minors. Greater support for testing among offspring could indicate increasing requests for early genetic diagnosis. Further research is necessary to explore the risks and benefits of providing genetic testing to minors for adult‐onset hereditary cancer syndromes in order to inform clinical practice and public policy and to ensure optimal psychosocial and medical outcomes for all members in families at risk for genetically determined disease. © 2008 Wiley‐Liss, Inc.
Polymeric cinchona alkaloids for the catalytic asymmetric dihydroxylation of olefins
Authors: Cha Rui‐tao , Wang Shao‐yu , Cheng Shao‐ling
Published: January 2008

Three cinchona alkaloid copolymers (PMMA‐BQTP, PMA‐BQTP, PAN‐BQTP) have been synthesized by copolymerization. Their structure was characterized by FTIR, GPC, and element analysis. The catalytic activity of these copolymers in asymmetric dihydroxylation (AD) of olefins by OsO4 was studied. The products enantiomeric excesses (ee) and the conversion of the substrate in the dihydroxylation reactions were determined using HPLC. The effect of time, temperature, and recycle times on the reaction was also discussed. The results showed that the copolymers catalyzed the dihydroxylation of the olefins to get diols in high optical yield. However, their catalytic efficiency was largely depended on the nature of olefins. The polymeric cinchona alkaloid can be simply recovered at the end of the reaction by centrifugation and then reused without radical change of activity or enantioselectivity. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Microcalorimetric Study on Effect of Chromium(III) and Chromium(VI) Species on the Growth ofEscherichia coli
Authors: YAO Jun , TIAN Lin , WANG Fei , CHEN Hui‐Lun , XU Chao‐Qian , SU Chun‐Li , CAI Ming‐Fa , MASKOW Thomas , ZARAY Gyulad , WANG Yan‐Xin
Published: January 2008

The effects of Cr(III) and Cr(VI) species (Cr2O72−, CrO42−and Cr3+) on the growth ofEscherichia coli(E. coli) have been investigated in detail by microcalorimetry at 37 °C. Parameters including the growth rate constant (k), inhibitory ratio (I), half‐inhibitory concentration (IC50), total heat output (Qtotal), time of the maximum heat production (tlog) in the log phase have been obtained. The results showed that Cr(VI) and Cr(III) had the inhibition effect on the growth ofE. coliin aquatic environment; however, the inhibitory ratio of Cr(III) toE. coliwas smaller than that of Cr(VI). Thekvalues ofE. coliin the presence of Cr(VI) and at high concentrations of Cr(III) were decreased with increasing the concentrations of these chromium species. Among the three chromium species investigated, Cr2O72−was found to be the most poisonous species againstE. coliwith an IC50value of 35.52 µg·mL−1. CrO42−exhibited moderate toxicity onE. coliwith an IC50of 50.24 µg·mL−1, and Cr3+had the lowest toxicity with an IC50of 84.30 µg·mL−1. Microcalorimetry can provide a convenient, sensitive and reliable method to study the effect of various metal species on the growth of bacteria or other microorganisms.
Study on the Retention Behavior of Aromatic Carboxylic and Sulfonic acid on a New Anion Exchange Column
Authors: SHI Ya‐Li , CAI Ya‐Qi , MOU Shi‐Fen
Published: January 2008

Ion chromatography (IC) has gradually developed into a preferred method for the determination of inorganic anions. And in recent years some low molecular aliphatic acid can be also separated in the ion exchange column with the development of stationary phase. But for the determination of aromatic ionic compounds there are some problems. The aromatic anions show enhanced retention due to interaction with the π electrons of the aromatic backbone. Although the addition of an organic modifier can alleviate the difficulty, it is not the ultimate solution. IonPac AS20 column was developed using a unique polymer bonding technology and its substrate coating is aliphatic backbone. The polymer is completely free of any π electron‐containing substituents in the AS20 column. In this paper, the retention behavior of aromatic carboxylic and sulfonic acid on two hydroxide‐selective columns, IonPac AS11‐HC, AS16, and the new column AS20 was also studied. The result showed that the retentions of ten compounds on three columns were different with each other because of their different column characteristics. Among them 4‐chlorobenzene sulfonic acid, 3,5‐dihydric benzoic acid and salicylic acid obviously exhibited the weakest retention on the IonPac AS20. It was showed that π‐π bond function between anion and stationary phases was weakened in AS20 column because its polymer was completely free of any π electron‐containing substituents. So in this paper the AS20 was selected as an analytical column to separate ten aromatic ionic compounds, fumaric acid with conjugate bond included. The retention behavior, separation of the ten compounds and effect of temperature on their retention in the anion‐exchange column AS20 (2 mm) were studied. The result showed that those compounds could be separated with each other when running in gradient program and the organic modifier was unnecessary during the separation. So it is showed that AS20 column can be used as a separating column because its polymer is completely free of any π electron‐containing substituents. Finally, the effect of temperature on the retention behavior in AS20 column was studied and it was showed that the retention of nine compounds exhibited endothermic behavior.
Synthesis of Lactosylated Piperazinyl Porphyrins and Their Biological Activity
Authors: LI He‐Ping , CAO Zhong , XIAO Hua‐Wu
Published: January 2008

The aim of this work is to synthesize of a new family of lactosylated piperazinly porphyrins, in which the galactoside piperazine moieties are linked to the tetra‐ and mono‐phenyl rings of tetraphenylporphyrin (TPP). 5,10,15,20‐Tetrakis[4‐(4‐lactobionylpiperazin‐1‐yl)phenyl]porphyrin (TLPP) and 5‐mono[4‐(4‐lactobionylpiperazin‐1‐yl)phenyl]‐10,15,20‐triphenylporphyrin (MLPP) have been synthesized. A detailed 1H NMR study gave their complete structural elucidation. The UV‐Visible, mass spectra and elemental analysis are also presented. The biological activity on cancer cells and the pharmacokinetics have also been evaluated, showing a better biological activity, a very high liver to skin ratio and short retention time in tissues. It was suggested that such novel lactosylated piperazinly porphyrins, as potential hepatocyte‐selective targeting drugs, exhibit a promising activity in photodynamic therapy (PDT).
Studies on the Photodynamic Mechanism of Tetrapyrrole Compounds by Laser Flash Photolysis
Authors: DENG Kui , CHEN Zhi‐Long , ZHOU Xing‐Ping , WANG Wen‐Feng , YANG Xiao‐Xia , TIAN Juan
Published: January 2008

Photodynamic therapy (PDT) is a promising new treatment technique which can potentially destroy unwanted and malignant tissues, such as those of cancer. The photodynamic mechanisms of three tetrapyrrole compounds: Mg‐purpurin‐18, tetra(meso‐chlorophenyl)porphyrin (m‐TCPP) and 2,7,12,18‐tetramethyl‐3,8‐di[(1‐isobutoxyl)‐ ethyl]‐13,17‐bis[3‐di(2‐chloroethyl)aminopropyl]porphyrin (TDBP) in acetonitrile were investigated by 355 nm laser flash photolysis. It was found that after laser flash photolysis (LFP), the excited states of TDBP and Mg‐purpurin‐18 could react with O2and1O2was produced, which proved that TDBP and Mg‐purpurin‐18 took effects through type II mechanism in PDT. This suggested that TDBP and Mg‐purpurin‐18 should be suitable for target tissues containing enough O2. Mg‐purpurin‐18 has two extra absorptions at 550 and 700 nm, which means it has broad choices of laser wavelength in PDT. It was also found thatm‐TCPP could be photoionized when excited with 355 nm laser under N2‐saturated condition. It could also react with O2to produce reactive oxygen species such as superoxide and the peroxide anions, but not1O2. These were known as the Type I mechanism. Som‐TCPP could be used even at low oxygen concentration or more polar environments with good behavior in PDT. From the above studies on the three different tetrapyrrole compounds it could be concluded that the structure of porphin ring takes a main role in PDT. And there was important impact on the photodynamic mechanism for the functional group directly connecting with porphin ring, while little influence for the functional group indirectly connecting with porphin ring. These will be of great value in the discovery of new PDT drugs.
Medication overuse headache: clinical features, pathogenesis and management
Authors: Couch James R. , Lenaerts Marc E.
Published: January 2008

Medication overuse headache (MOH) is a problem that is estimated to occur in up to 1% of the population. It is a common feature underlying chronic headache, especially chronic migraine. MOH represents a major diagnostic and therapeutic challenge. Many patients are referred to headache specialty clinics, where they can represent the majority of patients. The syndrome remains underdiagnosed and the role of symptomatic medication overuse in producing MOH is often underestimated. With proper education of medical providers, prevention of this too often intractable syndrome could be improved. The basis of therapy is discontinuance of the abused medication. Additional treatment relies on a multifaceted approach that embraces proper use of symptomatic pain medications and management of psychiatric comorbidities and also emphasizes patient education. Various pharmacological regimens, both abortive and prophylactic, are available. Further scientific study is warranted to elucidate the ultimate mechanisms of this syndrome and define more effective treatments. This article gives detailed clinical description, tentative pathophysiological explanation, and therapeutic suggestions. Drug Dev Res 68:449–460, 2007. © 2008 Wiley‐Liss, Inc.
Syk kinase is required for collaborative cytokine production induced through Dectin‐1 and Toll‐like receptors
Authors: Dennehy Kevin M. , Ferwerda Gerben , Faro‐Trindade Inês , Pyż Elwira , Willment Janet A. , Taylor Philip R. , Kerrigan Ann , Tsoni S. Vicky , Gordon Siamon , Meyer‐Wentrup Friederike , Adema Gosse J. , Kullberg Bart‐Jan , Schweighoffer Edina , Tybulewicz Victor , Mora‐Montes Hector M. , Gow Neil A. R. , Williams David L. , Netea Mihai G. , Brown Gordon D.
Published: January 2008

Recognition of microbial components by germ‐line encoded pattern recognition receptors (PRR) initiates immune responses to infectious agents. We and others have proposed that pairs or sets of PRR mediate host immunity. One such pair comprises the fungal β‐glucan receptor, Dectin‐1, which collaborates through an undefined mechanism with Toll‐like receptor 2 (TLR2) to induce optimal cytokine responses in macrophages. We show here that Dectin‐1 signaling through the spleen tyrosine kinase (Syk) pathway is required for this collaboration, which can also occur with TLR4, 5, 7 and 9. Deficiency of either Syk or the TLR adaptor MyD88 abolished collaborative responses, which include TNF, MIP‐1α and MIP‐2 production, and which are comparable to the previously described synergy between TLR2 and TLR4. Collaboration of the Syk and TLR/MyD88 pathways results in sustained degradation of the inhibitor of kB (IkB), enhancing NFkB nuclear translocation. These findings establish the first example of Syk‐ and MyD88‐coupled PRR collaboration, further supporting the concept that paired receptors collaborate to control infectious agents.
Prevalence of sclerosing cholangitis in adults with autoimmune hepatitis: Evaluating the role of routine magnetic resonance imaging
Authors: Abdalian Rupert , Dhar Preeti , Jhaveri Kartik , Haider Masoom , Guindi Maha , Heathcote Jenny E.
Published: January 2008

Large bile duct injury (that seen on cholangiography) is not usually considered a feature of autoimmune hepatitis (AIH) in adults but is present in up to 50% of children with AIH. The aim of this work was to study the prevalence of large bile duct abnormalities identified by magnetic resonance cholangiography (MRC) in adults given a diagnosis of AIH. Seventy-nine (n = 79) patients given a diagnosis of AIH (mean AIH score: 15.1 ± 3.4) were screened with MRC for evidence of sclerosing cholangitis (SC). Results were reviewed by two radiologists. Clinical parameters were correlated with MRC findings. A histological review of available liver biopsies (n = 29) was performed. Of the 79 patients surveyed, 8 (10%) had MRC findings consistent with primary sclerosing cholangitis (PSC). The interrater variability was excellent (kappa = 0.87). Younger age at diagnosis (24.3 ± 11.9), higher baseline alkaline phosphatase (186.4 ± 98.3), higher bilirubin at time of MRC (45.8 ± 37.2), and greater lobular activity on initial liver biopsy were significantly associated with the detection of this overlap of SC with AIH (

P

= 0.024,

P

= 0.037,

P

= 0.032, and

P

= 0.041, respectively), but not alkaline phosphatase/aspartate aminotransferase ratio, time between the initial diagnosis of AIH and the MRC, or the presence of cirrhosis on initial liver histology. Two cases with a normal MRC had histological lesions typical of small duct PSC.

Conclusion:

The presence of SC detected by MRC and from liver histology in adult patients with AIH may not be clinically overt, and thus the prevalence of this AIH/SC overlap may be higher than previously recognized. Our data suggest that routine radiological evaluation of the biliary tree should be performed in adults given a diagnosis of AIH, as in children the presence of this overlap negatively impacts on survival.
A novel nano‐micro structured octacalcium phosphate/protein composite coating on titanium by using an electrochemically induced deposition
Authors: Wang Hui , Lin Chang‐Jian , Hu Ren , Zhang Fan , Lin Li‐Wen
Published: January 2008

In this study, a novel nano‐micro structured octacalcium phosphate/protein (OCP/protein) composite coating has been successfully constructed on titanium substrate by using an electrochemically induced deposition technique. The structure and composition of the composite coating were investigated by XRD, XPS, SEM and FTIR. It is shown that the composite coating consists of OCP and protein with a highly ordered and hierarchically porous structure in nano‐micro scale, similar to the naturalbone structure. The nanoindentation experiment proves a good mechanical property for the OCP/protein composite coating on titanium substrate. In the osteoblast cell culture in vitro, the cell adhesion for the OCP/protein composite coating is observed to be greatly improved. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Sealing ability of a novel endodontic cement as a root‐end filling material
Authors: Asgary Saeed , Eghbal Mohammad Jafar , Parirokh Masoud
Published: January 2008

This study investigated the potential usage of novel endodontic cement (NEC) as a root‐end filling material by comparing its sealing ability with that of mineral trioxide aggregate (MTA) and intermediate restorative material (IRM). Sixty‐six single rooted extracted human teeth were cleaned, shaped, and obturated in a similar method. After root‐end resection, 3‐mm deep root‐end cavities were ultrasonically prepared. The samples were divided randomly into 3 test groups, having 20 roots each. Six roots were used as positive and negative controls. Samples were filled with test materials and after one day were immersed in methylene blue dye for 24 h. Roots were sectioned longitudinally and examined under stereomicroscope. Positive and negative controls responded as expected. The increasing order of mean dye microleakage values was NEC < MTA < IRM. ANOVA test showed statistically significant differences among experimental groups (p < 0.001). Tukey's test revealed no significant difference between NEC and MTA. It was concluded that the sealing ability of NEC and MTA is the same and superior to IRM. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Effect of pore size and interpore distance on endothelial cell growth on polymers
Authors: Narayan D. , Venkatraman S. S.
Published: January 2008

The endothelization of polymers using surface modification has received great attention. In particular, creation of physical surface features such as craters or pores has been an active area of research. However, there have been no reported studies of the effects of pore sizes (wide range) and interpore distance on endothelial cell growth. This report details the study done on endothelial cell attachment on the surfaces of polymers modified by porogen leaching. The polymeric system studied includes PLLA and PLGA (80/20). Factors such as porogen type, pore size, and interpore distance were varied, and the surface was evaluated for its influence on endothelial cell growth. Three groups of pore sizes were evaluated: small (5–20 μm), medium (20–45 μm), and large pores (45–90 μm). Two porogens were evaluated: sugar and gelatin. In addition to counting the attached endothelial cells, their proliferation was also quantified. Pore size and interpore distances were evaluated using scanning electron microscopy (SEM), and cell morphology was studied by staining with crystal violet. Analysis of variance demonstrated that the main parameters, pore size and interpore distance were significant in endothelial cell growth. In PLGA (80/20), it was found that endothelial cell growth was enhanced by smaller pore size and lower interpore distance, whereas the growth was poor on PLLA regardless of pore features. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Electromagnetic enhancement of a culture of human SAOS‐2 osteoblasts seeded onto titanium fiber‐mesh scaffolds
Authors: Fassina Lorenzo , Saino Enrica , Visai Livia , Silvani Giulia , Cusella De Angelis Maria Gabriella , Mazzini Giuliano , Benazzo Francesco , Magenes Giovanni
Published: January 2008

The surface properties of a biomaterial are fundamental to determine the response of the host tissue. In the present study, we have followed a particular biomimetic strategy where electromagnetically stimulated SAOS‐2 human osteoblasts proliferated and built a calcified extracellular matrix on a titanium fiber‐mesh surface. In comparison with control conditions, the electromagnetic stimulation (magnetic field intensity, 2 mT; frequency, 75 Hz) caused higher cell proliferation and increased surface coating with type‐I collagen, decorin, and osteopontin (9.8‐fold, 11.3‐fold, and 9.5‐fold, respectively). Reverse transcriptase‐polymerase analysis revealed the electromagnetically upregulated transcription specific for the foregoing matrix proteins and for the growth factor TGF‐β1. The immunofluorescence of type‐I collagen, decorin, and osteopontin showed their colocalization in the cell‐rich areas. The use of an electromagnetic bioreactor aimed at obtaining the surface modification of the biocompatible metallic scaffold in terms of cell colonization and coating with calcified extracellular matrix. The superficially modified biomaterial could be used, in clinical applications, as an implant for bone repair. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Laterally coupled and field‐induced quantum Hall systems
Authors: Habl M. , Wegscheider W.
Published: January 2008

A quantum Hall system which is divided into two laterally coupled subsystems by means of a tunneling barrier exhibits a complex Landau level dispersion. Magnetotunneling spectroscopy is employed to investigate the small energy gaps which separate subsequent Landau bands. The control on the Fermi level permits to trace the anticrossings for varying magnetic fields. The band structure calculation predicts a magnetic shift of the band gaps on the scale of the cyclotron energy. This effect is confirmed experimentally by a displacement of the conductance peaks on the axis of the filling factor. Tunneling centers within the barrier are responsible for quantum interferences between opposite edge channels. Due to the disorder potential, the corresponding Aharonov–Bohm interferometers generate additional long‐period and irregular conductance features. In the regime of strong localization, conductance fluctuations occur at small magnetic fields before the onset of the regular Landau oscillations. The Landau dispersion is obtained by a dedicated algorithm which solves the Schrödinger equation exactly for a single electron residing in a quantum Hall system with an arbitrary unidirectional, threefold staircase potential. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Review of (Quantitative) Structure–Activity Relationships for Acute Aquatic Toxicity
Authors: Netzeva Tatiana I. , Pavan Manuela , Worth Andrew P.
Published: January 2008

This paper reviews different approaches described in the literature for estimating the aquatic toxicity of chemical substances. It is based on an extended review performed by the European Chemicals Bureau of the European Commission's Joint Research Centre in support of the development of technical guidance for the implementation of the REACH legislation, and is one of a series of minireviews in this journal. The paper is organised by approach for (Q)SAR development and includes a review of: (i) (Q)SARs for acute aquatic toxicity by chemical class, (ii) (Q)SARs for acute aquatic toxicity by mode of action, (iii) review of statistically derived (Q)SARs, (iv) structural alerts for excess aquatic toxicity and (v) expert systems that combine structural rules and multiple (Q)SAR models to predict aquatic toxicological endpoints. Directions and recommendations for further research are also provided.
Variance Estimation of Nominal-Scale Inter-Rater Reliability with Random Selection of Raters
Authors: Gwet Kilem Li
Published: January 2008

Most inter-rater reliability studies using nominal scales suggest the existence of two populations of inference: the population of subjects (collection of objects or persons to be rated) and that of raters. Consequently, the sampling variance of the inter-rater reliability coefficient can be seen as a result of the combined effect of the sampling of subjects and raters. However, all inter-rater reliability variance estimators proposed in the literature only account for the subject sampling variability, ignoring the extra sampling variance due to the sampling of raters, even though the latter may be the biggest of the variance components. Such variance estimators make statistical inference possible only to the subject universe. This paper proposes variance estimators that will make it possible to infer to both universes of subjects and raters. The consistency of these variance estimators is proved as well as their validity for confidence interval construction. These results are applicable only to fully crossed designs where each rater must rate each subject. A small Monte Carlo simulation study is presented to demonstrate the accuracy of large-sample approximations on reasonably small samples.
Seroprevalence of parvovirus B19 in the German population
Authors: RÖHRER C. , GÄRTNER B. , SAUERBREI A. , BÖHM S. , HOTTENTRÄGER B. , RAAB U. , THIERFELDER W. , WUTZLER P. , MODROW S.
Published: January 2008

Acute parvovirus B19 infection is a risk for pregnant women. After vertical transmission the infected fetus may develop hydrops fetalis. Since B19 infection occurs mainly during childhood, children represent a main source for virus transmission. In order to determine whether certain groups in the German population show increased risks for B19 infection we analysed the seroprevalence using 6583 sera collected from adults in former Eastern and Western Germany during the German National Health Survey and 649 sera from healthy Thuringian children and adolescents. In adults the overall seroprevalence was 72·1%, rising from 20·4% in children (1–3 years) and 66·9% in adolescents (18–19 years) to 79·1% in the elderly (65–69 years). Significant differences were observed between females (73·3%) and males (70·9%) and between inhabitants of small (74·8%) and big cities (69·0%) but not between people of the former Eastern (72·8%) and Western states (72·0%) of Germany. For women during childbearing age (18–49 years) highest values were observed in those living together with two or more children (81·6%) and in women with occupational contact with children aged <6 years (88·9%). In contrast seroprevalence was significantly lower in age-matched female singles (64·8%) and in women with occupational contact with children aged >6 years and adolescents (63·8%).