bluuebunny/crossref_metadata_2025 huggingface dataset:
An Experimental Study On The Vasoconstriction Effect Of Calcium Hydroxide Using Rat Mesentery
Authors: Kikuchi Izumi , Wadachi Reiko , Yoshioka Takatomo , Okiji Takashi , Kobayashi Chihiro , Suda Hideaki
Published: February 2010

Calcium hyroxide has been used for eliminating persistent intracanal exudation. In order to address the mechanism behind this action, we investigated whether calcium hydroxide solutions cause the constriction of microvessels in the mesenteric microcirculation bed of rats. The exteriorised mesentery from anaesthetised rats was spread in a chamber, and arterioles, venules and capillaries were viewed under a digital microscope. Various concentrations of calcium hydroxide solutions were applied for 10 sec, and the diameter of the microvessels was recorded. In arterioles, calcium hydroxide solutions caused rapid and transient constriction. A statistically significant difference versus original diameter was detected I min after the application of 4.0 times 10−3 mol/l and 1.0 times 10−2 mol/l solutions (p < 0.05, one‐way analysis of variance and Tukey‐Kramer test). No statistically significant constriction occurred in capillaries and venules. It was concluded that the arteriolar constriction might be an explanation for the exudation‐controlling effect of intracanal calcium hyroxide dressings.
Contemporary Perspectives On Post‐Core Systems
Authors: Berekally Tom
Published: February 2010

The challenge of restoring endodontically‐treated teeth has spawned a considerable diversity in foundation restorations and a plethora of publications in the dental literature. Moreover, it seems that an inverse relationship has developed between the escalating complexity in selecting a post‐core system and the volume of reliable scientific data upon which clinicians base their treatment decisions. In the quest to restore aesthetics, function, and reduce the risk of treatment failure there is now a much greater emphasis on the preservation of sound tooth structure, tooth isolation for intracanal procedures, sealing the root canal and adapting the advantages and limitations of dental materials to the presenting clinical situation. The relatively recent introduction of metal‐free posts into mainstream prosthodontics has added an aesthetic dimension to treatment planning. New adhesive systems and resin‐based luting agents have the potential to create a genuine adhesive continuum between the tooth and post‐core complex. While these developments may have significant ramifications with respect to treatment prognosis, the long‐term clinical performance of contemporary post‐core systems is unclear.
Recent Advances In Therapeutic Exercise For The Neck: Implications For Patients With Head And Neck Pain
Authors: BPhty S. O'Leary , BPhty D. Falla , MPhty G. Jull
Published: February 2010

There have been recent advances in the rehabilitation of the muscles that control the head and neck. These advances are based on evidence of specific neck muscle dysfunction in individuals with persistent head and neck pain. Traditional rehabilitation strategies have focused predominantly on muscle strength and endurance under high loads. New evidence suggests that in people with neck pain there are underlying neuromuscular problems that may require more immediate attention and may not be adequately addressed by simple strength and high‐load endurance retraining. Evidence of altered coordination between the deep and superficial neck muscles, greater neck muscle fatigue under sustained low loads, and deficits in kinaesthetic sense have been identified in symptomatic individuals. There is evidence to indicate that addressing these muscle control problems, with specific gentle exercise strategies, results in a reduction in neck pain and associated symptoms.
Unusual Maxillary Lateral Incisors: Case Reports
Authors: Low Danny , Chan Alex W.K.
Published: February 2010

Root canal morphology is often complex and the number of root canals may vary for any type of tooth. Abnormalities in the root canal morphology of maxillary lateral inciors are rare. Maxillary lateral incisors can have two root canals, even though the dental literature supports their 100% single‐canal anatomy. It is vital to consider the possibility of extra root canal(s), even in teeth with a low frequency of abnormal root canal anatomy. This report presents two cases of maxillary lateral incisors with two root canals.
Endodontic Treatment In The Primary Dentition
Authors: Koshy Sajeev , Love Robert M.
Published: February 2010

A number of factors are involved in the development of pulp and periapical disease in primary and permanent teeth, with dental caries being the main factor. Although these factors are similar, the clinical management of a primary or permanent tooth with pulp or periapical disease may be quite different. This is based mainly on the differences between the two types of teeth, with primary tooth longevity, coronal structural integrity, root canal morphology, and root anatomy being important features to be taken into account when treatment planning. This paper reviews some aspects of primary teeth and the various treatment options for the management of pulp and periapical disease.
Photo‐Activated Disinfection Of The Root Canal: A New Role For Lasers In Endodontics
Authors: Lee Michael T. , Bird Philip S. , Walsh Laurence J.
Published: February 2010

Because micro‐organisms play a crucial role in the development of pulpal and periapical disease, the prognosis of endodontic therapy is intimately related to the presence of bacteria within the root canal system. Micro‐organisms may persist in the apical region of the root canal system despite chemomechanical preparation. The usefulness of Class IV lasers (such as Nd:YAG, diode, KTP and Er:YAG) for photo‐thermal disinfection of the root canal has been demonstrated in numerous studies.

An alternative approach to microbial killing in the root canal system by laser light involves the use of low‐power lasers to drive a photochemical reaction that produces reactive oxygen species, a technique termed photo‐activated disinfection (PAD). By using exogenous photosensitisers such as tolonium chloride, killing of all types of bacteria can be achieved. In vitro studies of PAD have demonstrated its ability to kill photosensitised oral bacteria (such as E. faecalis), and more recently microbial killing in vivo in the root canal system has been demonstrated. While PAD can be undertaken as part of the routine disinfection of the root canal system, it also has potential use for eradicating persistent endodontic infections for which conventional methods have been unsuccessful.
Biologic Perspectives To Support Clinical Choices In Root Canal Treatment
Authors: Gutmann James L.
Published: February 2010

Some of the most keenly debated issues in endodontics have revolved around the where to end the root filling, as well as cleaning and shaping and obturation techniques. In some respects, original scientifically‐based concepts have been abandoned in favour of clinical techniques that may provide aesthetically pleasing radiographs, but do not necessarily support tissue regeneration around the root apex following obturation. Recently advocated obturation techniques supporting the use of resin‐based and bonded materials have not had the same extensive evaluation that gutta‐percha, when in contact with the periradicular tissues, has had. Further studies are necessary so that evidence‐based data can support the confident use of these innovative materials.
Apically‐Extruded Debris Using The ProTaper System
Authors: Azar Nasim Gheshlaghi , Ebrahimi Gholamreza
Published: February 2010

The purpose of this in vitro study was to determine the quantity of debris and irrigant extruded apically using the ProTaper system compared to ProFiles and K‐Flexofiles.

Thirty‐six mesio‐buccal root canals of human mandibular molars were selected and divided into three groups of twelve canals. Two groups were instrumented with ProFiles and ProTapers according to the manufacturer's instructions. The other group was instrumented with K‐Flexofiles using the step‐back technique. A standard amount of irrigant was used for each canal. Apically‐extruded debris and irrigant was collected in pre‐weighed vials. The mean weight of extruded debris and irrigant for each group was statistically analysed using Student's t‐test and one‐way ANOVA.

All instrumentation techniques produced extruded debris and irrigant. Although the mean amount of extrusion with the step‐back technique was higher than the two rotary systems, there was no significant difference between the three groups (p > 0.05).

NiTi rotary systems were associated with less apical extrusion, but were not significantly better than hand file instrumentation. All techniques extruded debris.
Relationship Of Patient Complaints And Signs To Histopathologic Diagnosis Of Pulpal Condition
Authors: Cisneros‐Cabello Rafael , Segura‐Egea Juan José
Published: February 2010

The correlation between the histopathologic examination of pulp biopsy specimens and patients' complaints and signs was investigated. The sensitivity, specificity and reliability of each complaint and sign, and the characteristics of pain that are associated with treatable and untreatable pulp states is proposed. Pulp specimens were obtained from teeth that required endodontic treatment. Clinical data were recorded to identify each patient's complaints. The pulp specimens were processed and the histopathologic diagnoses were categorised and correlated with the patients' complaints. Of the 240 cases, 100 (41.7%) were diagnosed as atrophic pulp or pulposis; 4 (1.7%) as acute pulpitis; 64 (26.7%) as transitional stage; 56 (23.3%) as chronic pulpitis, and 16 (6.7%) as acute pulpitis superimposed on a chronic pulpitis. Results showed that previous pain (p < 0.05), spontaneous pain (p < 0.01), and prolonged pain on cold stimuli (p < 0.05), were significantly more frequent in the patients with chronic pulpitis compared to those with pulposis or transitional stage. We concluded that clinicians must consider the sensitivity and specificity of patient complaints and signs in order to perform a diagnosis based upon clinical evidence.
Diagnosis And Treatment Planning Are Essential Prior To Commencing Endodontic Treatment: Discuss This Statement As It Relates To Clinical Endodontic Management
Authors: Stewart Trudy
Published: February 2010

Diagnosis and treatment planning are essential to the practice of endodontics. Diagnosis aims to determine whether pathological involvement of the dental pulp has or is occurring. Treatment planning meanwhile, involves appropriately selecting cases, determining how difficult the treatment may be to perform on a specific individual and sequencing treatment procedures to achieve a healthy and functional dentition. In endodontic management, this may involve establishing whether the tooth is restorable and periodontally sound, the patient is able to tolerate the treatments and the clinician has the skills to perform the required treatment procedures. Careful consideration of these issues must be given prior to commencing treatment.
A Comparison Of Tissue Reaction To MTA And An Experimental Root‐End Restorative Material In Rats
Authors: Modaresi Jalil , Yavari S. Amir Saeid , Dianat S. Omid , Shahrabi Shokufeh
Published: February 2010

The purpose of this study was to compare the biocompatibility of a new experimental root‐end filling material, “Cold Ceramic” (CC). with mineral trioxide aggregate (MTA) in rats. After anaesthetising 10 rats and raising tissue flaps, tablets of the material were placed subcutaneously. Five rats were followed for seven days and five for 30 days. An incision without any implanted material was used as a control. Histological analyses were performed with regard to number, type and location of the inflammatory cells and type of surrounding tissue. Kruskal‐Wallis and Mann‐Whitney statistical tests were used. Comparing inflammatory reactions between the two experimental groups (MTA and CC) and the control group showed significant differences after seven days (p = 0.031). There were no significant differences between CC and MTA groups after seven days (p = 0.222) and after 30 days (p = 0.063). The results suggested that MTA and CC are both biocompatible. It appears that MTA induces less inflammatory response in short periods of observation, but CC may be more biocompatible for slightly longer periods.
Maxillary Second Premolar With Three Roots And Three Separate Root Canals — Case Reports
Authors: Velmurugan N. , Parameswaran A. , Kandaswamy D. , Smitha A. , Vijayalakshmi D. , Sowmya N.
Published: February 2010

Aberrations in root canal systems are a commonly occurring phenomenon. Knowledge of the basic root canal anatomy and its variation is necessary for successful completion of endodontics. Maxillary second premolars usually have one root and one canal. The occurrence of these teeth having three roots and three canals is very rare. Three such cases of maxillary second premolar with three roots and three canals are presented here.
What We Leave Behind In Root Canals After Endodontic Treatment: Some Issues and Concerns
Authors: Sum Chee Peng , Neo Jennifer , Kishen Anil
Published: February 2010

The benefits of using sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid (EDTA) as endodontic irrigants, and calcium hydroxide as an inter‐appointment medicament, are well known to dentists. Many steps undertaken during endodontic treatment and retreatment are rather mechanical in nature, and less attention is committed to understanding the biological issues underlying endodontic treatment and retreatment. It should be noted that dentine is the fundamental substrate in endodontic treatment, and its properties and characteristics are the key determinant of nearly all disease and post‐disease processes in the teeth. In this article the effects and counter‐effects of NaOCl and EDTA on root canal dentine, and some other related issues are reviewed. This information will enable clinicians to use the beneficial effects of these chemicals, while necessary steps are considered to reduce their harmful effects on dentine substrate.
The Envelope Damage of Tetrahymena in the Presence of TiO2 Combined with UV Light
Authors: Peng Liu , Wenli Duan , Qisui Wang , Xi Li
Published: February 2010

The biological consequences of exposure to TiO2, UV light and their combined effects were studied on the cellular envelopes of Tetrahymena. For Tetrahymena cells treated with TiO2 or UV light alone, the cell membrane shrunk while still maintaining the original elliptoid shape. Cells treated by TiO2 under UV light irradiation experienced the most serious damage by peroxidation. A pear‐shaped cell was formed due to serious shrinkage and cilia loss. An increase in the fluorescence polarization of 1,6‐diphenyl‐1,3,5‐hexatriene was observed, indicating a significant decrease in membrane fluidity. Quantum dot (QD) labeling revealed that damaged cells could not function properly or absorb extracellular materials selectively. QDs were able to enter the damaged cells or be absorbed on the cell surface. Attenuated total reflection Fourier transform infrared spectra revealed that amide groups and PO2− of the phospholipid phospho‐diester, both in the hydrophobic end exposed to the outer layer, were the easiest to be oxidized. Other groups like CH2 and CH3 were also involved, but showed a resistance to photocatalytic peroxidation. The differences can be attributed to the bond energy as well as the ordering and position of the groups.
Optical Properties of Fluorescein‐labeled Organoclay
Authors: Lee Young‐Chul , Lee Tae‐Ho , Han Hyo‐Kyung , Go Woon Jung , Yang Ji‐Won , Shin Hyun‐Jae
Published: February 2010

We report the preparation of aminopropyl‐functionalized magnesium phyllosilicate (Mg‐organoclay) conjugated to fluorescein isothiocyanate (FITC) functionality (FITC‐organoclay) by one‐pot sol‐gel synthesis. The physical characteristics of the Mg‐ and FITC‐organoclays were examined by scanning electron microscopy (SEM), X‐ray diffraction (XRD), FT‐IR and UV–Vis spectrophotometry. X‐ray fluorescence and elemental analysis were conducted to confirm the composition of the Mg‐organoclay. The FITC‐organoclay particles were polydispersed with an average particle size of ∼50 nm, as determined from SEM images. The XRD patterns of FITC‐organoclay exhibited broad peaks and reduced basal d001 indicating a less condensed and more disordered structure than was observed for Mg‐organoclay. The conjugation between FITC‐ and Mg‐organoclay was characterized by FT‐IR spectroscopy. Fluorescence excitation and emission spectral data demonstrated the successful conjugation of FITC dye molecules to the Mg‐organoclay. The time‐resolved fluorescence measurements revealed that FITC had a lifetime of 4.58 ns, whereas the lifetime of FITC‐organoclay required a double exponential fit (τ1,2 = 0.72 and 2.68 ns). As a result, the lifetime of the FITC‐organoclay was shorter than that of FITC in ethanol and indicated moderate photostability in the solution state. The cellular uptake of FITC‐organoclay in human lung alveolar carcinoma epithelial cells (A549) was quantified and characterized.
Credit Spreads with Jump Risks and Stationary Leverage Ratio*
Authors: Kim Hwa‐Sung
Published: February 2010

Recent structural models have utilized new factors to enhance their exploratory power over credit spreads. Some studies have shown that jump risks allow us to obtain credit spreads that are more realistic. However, according to the empirical studies on capital structure, another factor that affects credit spreads is the stationary leverage ratio of a firm. The present paper develops a simple structural model and incorporates both jump risks and the stationary leverage ratio to explain credit spreads. In comparison to the existing jump‐diffusion structural model, this model generates a larger credit spread, which is more consistent with observed credit spreads, especially for investment‐grade bonds. This paper also shows that jump frequency and size may be significant factors determining credit spreads for firms.
Pricing of Private Placements of Equity
Authors: Chung Jaiho , Hwang Joon Ho
Published: February 2010

Building on the models of Benveniste & Spindt (1989) and Maksimovic & Pichler (2006), the present paper examines the optimal pricing and allocation mechanism for private placements of equity. Our model shows that for firms that receive favorable information prior to private placements, both the information acquisition cost and the value of information affect the offer discount. However, for firms that receive unfavorable information, only the information acquisition cost is the driving force behind the discount. We also show that the value of information has a greater impact on the discount level in private offerings compared to public offerings. However, the information acquisition cost has a greater effect on the discount in public offerings than in private placements.
Break-Up of Stepped Platinum Catalyst Surfaces by High CO Coverage
Authors: Tao Feng , Dag Sefa , Wang Lin-Wang , Liu Zhi , Butcher Derek R. , Bluhm Hendrik , Salmeron Miquel , Somorjai Gabor A.
Published: February 2010

From Steps to Clusters

When a flat surface of a single crystal is formed by cutting or cleavage, the atoms may move little from their bulk positions, or the surface may reconstruct as the atoms move to more energetically favorable positions. The adsorption of molecules can also change the energetic landscape and cause reconstruction.

Tao
et al.

(p.
850
; see the Perspective by
Altman
) examined “stepped” platinum surfaces, the (557) and (332) surfaces in which flat terraces are connected by atomic steps. Scanning tunneling microscopy and x-ray photoelectron spectroscopy revealed a reversible breakup into nanometer-scale clusters when CO surface coverages were very high. Density functional theory calculations suggest that this new morphology increases the number of edge sites for adsorption and relieves unfavorable CO-CO repulsions.
Spin-Dependent Quantum Interference Within a Single Magnetic Nanostructure
Authors: Oka H. , Ignatiev P. A. , Wedekind S. , Rodary G. , Niebergall L. , Stepanyuk V. S. , Sander D. , Kirschner J.
Published: February 2010

Wave-Particle Duality

The dual-wave nature of particles is nowhere more evident than in a confined space, where standing waves are formed with wavelengths that depend on particle energy. This so-called quantum interference has been observed in nanostructures using surface probes such as scanning tunneling microscopy. Now,

Oka
et al.

(p.
843
) use the spin-polarized version of this technique to study spin-dependent quantum interference on a triangular nanoscale cobalt island deposited on a copper surface. They observe the modulation of the magnetization, with the pattern depending on the energy of the interfering electrons. The experimental results are in good agreement with simulations, which indicate that the magnetization at a given energy and position largely depends on which of two electron spin states present dominates.
Breeding Technologies to Increase Crop Production in a Changing World
Authors: Tester Mark , Langridge Peter
Published: February 2010

To feed the several billion people living on this planet, the production of high-quality food must increase with reduced inputs, but this accomplishment will be particularly challenging in the face of global environmental change. Plant breeders need to focus on traits with the greatest potential to increase yield. Hence, new technologies must be developed to accelerate breeding through improving genotyping and phenotyping methods and by increasing the available genetic diversity in breeding germplasm. The most gain will come from delivering these technologies in developing countries, but the technologies will have to be economically accessible and readily disseminated. Crop improvement through breeding brings immense value relative to investment and offers an effective approach to improving food security.
Low-Frequency Modes of Aqueous Alkali Halide Solutions: Glimpsing the Hydrogen Bonding Vibration
Authors: Heisler Ismael A. , Meech Stephen R.
Published: February 2010

Salty Stretch

What happens at the molecular level when salt dissolves in water? Much of the data characterizing the geometry and dynamics of ion solvation shells has come from indirect observation of the surrounding water structure. Using a time domain Raman technique based on the interference of four ultrashort polarized light pulses,
Heisler and Meech
(p.
857
) have now mapped directly the stretching vibrations associated with the weak hydrogen bonding interactions between bulk water molecules and chloride, bromide, or iodide ions.
Feasting on Minerals
Authors: Newman Dianne K.
Published: February 2010

Molecular studies are elucidating how microbes can eat iron-containing rocks, but many questions remain.
Reaping Benefits of Crop Research
Authors: Baulcombe David
Published: February 2010

In 2009, for the first time since the 1950s and the early stages of the Green Revolution, food security was taken seriously by policy-makers. There was substantial output from the International Assessment of Agricultural Knowledge, Science and Technology for Development, and with studies by the U.S. National Academy of Sciences and a UK government Foresight group due this year, there is no sign that this renewed interest will fade. This revival follows assessments by the United Nations Food and Agriculture Organization and others that population growth, urbanization, climate change, and the availability of natural resources present a challenge to global food security. Somehow the world must produce 50 to 100% more food than at present under environmental constraints that have not applied in the past.
Genetic Control of Hotspots
Authors: Cheung Vivian G. , Sherman Stephanie L. , Feingold Eleanor
Published: February 2010

Both chromatin and DNA sequence account for individual differences in the location and frequency of genetic recombination.
Propelling Progeny
Authors: Pickup David J.
Published: February 2010

Newly infected cells use microvilli to propel extracellular enveloped virions along their surfaces, accelerating transmission to uninfected cells.
Reading Your Genes
The Language of Life
DNA and the Revolution in Personalized Medicine

by Francis S. Collins

Harper, New York, 2010. 360 pp. $26.99. ISBN 9780061733178.
Authors: Harris Tim
Published: February 2010

Writing for the general public, NIH director Collins discusses what DNA can reveal about the health and health risks of individuals.
New Delay of Large Hadron Collider Might Not Keep Its Rival on the Job
Authors: Cho Adrian
Published: February 2010

The world's highest-energy atom smasher, the Large Hadron Collider, will run at half its maximum energy through 2011 and not at all in 2012, officials at the European particle physics laboratory, CERN, announced last week.
After Acrimonious Debate, India Rejects GM Eggplant
Authors: Bagla Pallava
Published: February 2010

At a press conference here on 9 February, India's environment minister announced a "moratorium" on commercial release of what would have been India's first genetically modified food crop: varieties of eggplant, called brinjal in India, equipped with a protein from the bacterium
Bacillus thuringiensis
that's toxic to insect pests.
China's Push to Add by Subtracting Fertilizer
Authors: Hvistendahl Mara
Published: February 2010

Soil scientists are showing farmers that reducing fertilizer use can improve crop yields without adding to environmental problems.
Could Less Meat Mean More Food?
Authors: Stokstad Erik
Published: February 2010

If people in the developed world ate less meat, it would free up a lot of plants to feed billions of hungry people and gain a lot of good farmland. Some food-security researchers, however, are skeptical; they say the complexities of global markets and human food traditions could also produce some counterintuitive—and possibly counterproductive—results.
For More Protein, Filet of Cricket
Authors: Vogel Gretchen
Published: February 2010

As the world diverts more of its grain harvests into producing meat, some scientists are pushing policymakers to take a closer look at insects as an environmentally friendlier source of protein.
Promising Rabies Vaccine for Postexposure Prophylaxis in Developing Countries, a Purified Vero Cell Vaccine Produced in China
Authors: Wang Chuanlin , Zhang Xiaowei , Song Qingkun , Tang Kun
Published: February 2010

We evaluated the immunogenicity, safety, and antibody persistence of a Vero cell rabies vaccine manufactured in China, compared with those of Verorab. Adequate titers of antibody were observed for the two vaccines. ChengDa rabies vaccine could be a promising alternative vaccine for many developing countries which cannot afford expensive rabies vaccines.
Etiological Spectrum of Clinically Diagnosed Japanese Encephalitis Cases Reported in Guizhou Province, China, in 2006
Authors: Xufang Ye , Huanyu Wang , Shihong Fu , Xiaoyan Gao , Shuye Zhao , Chunting Liu , Minghua Li , Yougang Zhai , Guodong Liang
Published: February 2010

The proportion of laboratory-confirmed Japanese encephalitis (JE) virus (JEV) infections was compared to the number of JE cases reported on the basis of seasonality and the clinical symptoms of hospitalized patients in Guizhou Province, China, between April and November 2006. Of the 1,837 patients with reported JE, 1,382 patients in nine prefectures were investigated. JE was confirmed in 1,210 of 1,382 (87.6%) patients by a JEV-specific immunoglobulin M (IgM) antibody-capture enzyme-linked immunosorbent assay (MAC-ELISA), heminested reverse transcriptase PCR, and virus isolation. Two strains of JEV belonging to genotype 1 were isolated. Other viral pathogens responsible for encephalitis, including echovirus, mumps virus, herpes simplex virus, and cytomegalovirus, were identified in 67 of 172 (38.9%) JE-negative cases. On the basis of the distribution of the laboratory-confirmed JE cases from different hospitals according to the Chinese administrative division, which included hospitals at the provincial, city, county, and township levels, county hospitals detected the highest number of JE cases (81.8%), whereas township hospitals detected the smallest number of JE cases (1.4%). Provincial and city hospitals had the highest and lowest rates of accuracy of providing a clinical diagnosis of JE, as confirmed by laboratory testing (91.8% and 76.7%, respectively). This study demonstrates that laboratory confirmation improves the accuracy of diagnosis of JE and that an enhanced laboratory capacity is critical for JE surveillance as well as the identification of other pathogens that cause encephalitic syndromes with clinical symptoms similar to those caused by JEV infection.
Globicatella sanguinis
Meningitis Associated with Human Carriage
Authors: Héry-Arnaud Geneviève , Doloy Alexandra , Ansart Séverine , Le Lay Geneviève , Le Flèche-Matéos Anne , Seizeur Romuald , Garré Michel , Payan Christopher , Bouvet Anne
Published: February 2010

Globicatella sanguinis
is a rare cause of acute meningitis. We demonstrated human carriage of
Globicatella
by identifying cefotaxime-resistant strains in groin and rectal specimens 9 months after invasive infection. The pathogenic strain isolated from the cerebrospinal fluid and the carriage strains were accurately identified by
sodA
gene sequence analysis.
Public Hospital-Based Laboratory Experience during an Outbreak of Pandemic Influenza A (H1N1) Virus Infections
Authors: Leonardi Gary P. , Mitrache Ileana , Pigal Ana , Freedman Lester
Published: February 2010

The experience of a public hospital virology laboratory during a springtime 2009 outbreak of a novel influenza A (H1N1) virus in New York State is described. Influenza virus was isolated from 145 of 613 respiratory swab specimens. Symptoms of fever (temperature, 102.7 ± 0.32°F), cough, upper respiratory infection, myalgia, and headache were reported. Atypical symptoms of nausea/vomiting and diarrhea were also observed. Illness occurred mainly in patients ≤21 years of age (85/145 patients). Only two patients were ≥65 years old. Compared to the results of traditional culture methods, the sensitivities of a rapid chromatographic influenza A and B virus immunoassay and rapid shell vial culture were 70.3% and 98.6%, respectively. A sensitivity of 80% was obtained by testing 50 specimens by a direct fluorescent-antibody (DFA) assay. The observation of adequate numbers of cells on the DFA assay slides suggests that the low sensitivity of the chromatographic immunoassay may result from its intrinsic nature and not from improper specimen collection. A reverse transcription-PCR (RT-PCR) assay of 45 specimens performed off-site yielded 21 novel (H1N1) viruses and 2 seasonal (H3N2) influenza viruses. The mean time interval of 5.69 ± 0.37 days from specimen collection to the availability of RT-PCR results limited the value of this assay for patient care. In laboratories lacking on-site molecular capabilities, shell vial techniques can rapidly (about 1 day) confirm negative results and/or identify false-negative chromatographic immunoassay results. Laboratories lacking culture capabilities may also use the DFA assay to confirm or replace the results obtained by these immunoassays. Increasing testing demands caused shortages in commodities and personnel. Alternative testing strategies and planning are necessary in order to optimize virus detection and ensure appropriate resource allocation.
Two Unusual Cases of Severe Soft Tissue Infection Caused by
Streptococcus dysgalactiae
subsp.
equisimilis
Authors: Kittang Bård Reiakvam , Langeland Nina , Skrede Steinar , Mylvaganam Haima
Published: February 2010

We present two cases of invasive infection caused by
Streptococcus dysgalactiae
subsp.
equisimilis
, one that showed rapidly developing necrotizing fasciitis in a previously healthy man and one that showed severe cellulitis and septic shock even though the bacterium possessed a mutated
emm
gene, predicted to encode a truncated M protein.
Cost-Effective Modification of a Commercial PCR Assay for Detection of Methicillin-Resistant or -SusceptibleStaphylococcus aureusin Positive Blood Cultures
Authors: Munson Erik , Kramme Timothy , Culver Anne , Hryciuk Jeanne E. , Schell Ronald F.
Published: February 2010

Real-time detection of methicillin-resistantStaphylococcus aureus(MRSA) and methicillin-susceptibleS. aureus(MSSA) in cases of clinical bacteremia may promote appropriate antimicrobial therapy and infection control. Expense inherent to molecular diagnostics may prevent laboratories from utilizing real-time PCR for this purpose. BD GeneOhm StaphSR assay master mix was reconstituted and aliquoted into SmartCycler tubes in 25-μl volumes (freshly reconstituted master mix), with a portion being frozen at −70°C (frozen master mix). Incubation of 40 previously analyzed lysates from positive BacT/Alert SA and SN blood culture bottles (identified as 10 MRSA strains, 10 MSSA strains, 12 coagulase-negativeStaphylococcusstrains, and 8Micrococcusstrains) in freshly reconstituted master mix and master mix frozen between 1 week and 6 months generated the expected results in all PCRs. Similarly, positive- and negative-control reagents stored frozen at −70°C for up to 18 weeks yielded the expected reactions. Prospective analysis of 244 positive blood culture samples utilizing 1-week-frozen master mix and freshly reconstituted master mix yielded a 1.2% discordant rate upon initial testing due to three unresolved results (two unresolved results for freshly reconstituted master mix and one unresolved result for frozen master mix). Repeat testing produced a final 100% concordance rate between the two master mix preparations. Use of master mix that was frozen up to 6 months did not compromise performance of the BD GeneOhm StaphSR assay. This modification, resulting in less reagent waste, may allow a greater number of laboratories to consider real-time PCR methodology for detection of bacteremia caused by MRSA and MSSA.
Mechanisms Responsible for a ΦX174 Mutant's Ability To InfectEscherichia coliby Phosphorylation
Authors: Cox Jennifer , Putonti Catherine
Published: February 2010

The ability for a virus to expand its host range is dependent upon a successful mode of viral entry. As such, the host range of the well-studied ΦX174 bacteriophage is dictated by the presence of a particular lipopolysaccharide (LPS) on the bacterial surface. The mutant ΦX174 strain JACS-K, unlike its ancestor, is capable of infecting both its native hostEscherichia coliC andE. coliK-12, which does not have the necessary LPS. The conversion of an alanine to a very reactive threonine on its virion surface was found to be responsible for the strain's expanded host range.
Ablation of the Complementarity-Determining Region H3 Apex of the Anti-HIV-1 Broadly Neutralizing Antibody 2F5 Abrogates Neutralizing Capacity without Affecting Core Epitope Binding
Authors: Julien Jean-Philippe , Huarte Nerea , Maeso Rubén , Taneva Stefka G. , Cunningham Annie , Nieva José L. , Pai Emil F.
Published: February 2010

The identification and characterization of broadly neutralizing antibodies (bnAbs) against HIV-1 has formed a major research focus, with the ultimate goal to help in the design of an effective AIDS vaccine. One of these bnAbs, 2F5, has been extensively characterized, and residues at the apex of its unusually long complementarity-determining region (CDR) H3 loop have been shown to be crucial for neutralization. Structural studies, however, have revealed that the
100
TLFGVPI
100F
apex residues of the CDR H3 loop do not interact directly with residues of its core gp41 epitope. In an attempt to gain better insight into the functional role of this element, we have recombinantly expressed native 2F5 Fab and two mutants in which either the apical Phe100B(H) residue was changed to an alanine or the CDR H3 residues
100
TLFGVPI
100F
were replaced by a Ser-Gly dipeptide linker. Isothermal titration calorimetry (ITC) and competitive-binding enzyme-linked immunosorbent assays (ELISAs) rendered strikingly similar affinity constants (

K
d

[dissociation constant] of ∼20 nM) for linear peptide epitope binding by 2F5 Fabs, independent of the presence or absence of the apex residues. Ablation of the CDR H3 apex residues, however, abolished the cell-cell fusion inhibition and pseudovirus neutralization capacities of 2F5 Fab. We report competitive ELISA data that suggest a role of 2F5 CDR H3 apex residues in mediating weak hydrophobic interactions with residues located at the C terminus of the gp41 membrane proximal external region and/or membrane components in the context of core epitope binding. The present data therefore imply an extended 2F5 paratope that includes weak secondary interactions that are crucial for neutralization of Env-mediated fusion.
Simian Virus 40 T/t Antigens and Lamin A/C Small Interfering RNA Rescue the Phenotype of an Epstein-Barr Virus Protein Kinase (BGLF4) Mutant
Authors: Meng Qiao , Hagemeier Stacy R. , Kuny Chad V. , Kalejta Robert F. , Kenney Shannon C.
Published: February 2010

The Epstein-Barr virus (EBV)-encoded viral protein kinase, EBV-PK (the BGLF4 gene product), is required for efficient nuclear viral egress in 293 cells. However, since EBV-PK phosphorylates a number of different viral and cellular proteins (including lamin A/C), the relative importance of each target during lytic viral replication remains unclear. We show here that an EBV PK mutant (PKmut; containing stop codons at residues 1 and 5 in EBV-PK) is highly defective for release of infectious virus from 293 cells but not 293T cells. Furthermore, the phenotype of the PKmut in 293 cells is substantially reversed by expression of the simian virus 40 (SV40) large (T) and small (t) T antigens. Efficient rescue requires the presence of both SV40 T/t proteins. We show that 293T cells have a much higher level of constitutive lamin A/C phosphorylation than do 293 cells over residues (S22 and S392) that promote phosphorylation-dependent nuclear disassembly and that both large T and small t contribute to enhanced lamin A/C phosphorylation. Finally, we demonstrate that knockdown of lamin A/C expression using small interfering RNA also rescues the PKmut phenotype in 293 cells. These results suggest that essential roles of EBV-PK during lytic viral replication include the phosphorylation and dispersion of lamin A/C.
Venezuelan Equine Encephalitis Virus Capsid Protein Forms a Tetrameric Complex with CRM1 and Importin α/β That Obstructs Nuclear Pore Complex Function
Authors: Atasheva Svetlana , Fish Alexander , Fornerod Maarten , Frolova Elena I.
Published: February 2010

Development of the cellular antiviral response requires nuclear translocation of multiple transcription factors and activation of a wide variety of cellular genes. To counteract the antiviral response, several viruses have developed an efficient means of inhibiting nucleocytoplasmic traffic. In this study, we demonstrate that the pathogenic strain of Venezuelan equine encephalitis virus (VEEV) has developed a unique mechanism of nuclear import inhibition. Its capsid protein forms a tetrameric complex with the nuclear export receptor CRM1 and the nuclear import receptor importin α/β. This unusual complex accumulates in the center channel of the nuclear pores and blocks nuclear import mediated by different karyopherins. The inhibitory function of VEEV capsid protein is determined by a short 39-amino-acid-long peptide that contains both nuclear import and supraphysiological nuclear export signals. Mutations in these signals or in the linker peptide attenuate or completely abolish capsid-specific inhibition of nuclear traffic. The less pathogenic VEEV strains contain a wide variety of mutations in this peptide that affect its inhibitory function in nuclear import. Thus, these mutations appear to be the determinants of this attenuated phenotype. This novel mechanism of inhibiting nuclear transport also shows that the nuclear pore complex is vulnerable to unusual cargo receptor complexes and sheds light on the importance of finely adjusted karyopherin-nucleoporin interactions for efficient cargo translocation.
Low pH-Induced Conformational Change in Herpes Simplex Virus Glycoprotein B
Authors: Dollery Stephen J. , Delboy Mark G. , Nicola Anthony V.
Published: February 2010

Herpesviruses can enter host cells using pH-dependent endocytosis pathways in a cell-specific manner. Envelope glycoprotein B (gB) is conserved among all herpesviruses and is a critical component of the complex that mediates membrane fusion and entry. Here we demonstrate that mildly acidic pH triggers specific conformational changes in herpes simplex virus (HSV) gB. The antigenic structure of gB was specifically altered by exposure to low pH both
in vitro
and during entry into host cells. The oligomeric conformation of gB was altered at a similar pH range. Exposure to acid pH appeared to convert virion gB into a lower-order oligomer. The detected conformational changes were reversible, similar to those in other class III fusion proteins. Exposure of purified, recombinant gB to mildly acidic pH resulted in similar changes in conformation and caused gB to become more hydrophobic, suggesting that low pH directly affects gB. We propose that intracellular low pH induces alterations in gB conformation that, together with additional triggers such as receptor binding, are essential for virion-cell fusion during herpesviral entry by endocytosis.
Electrostatic effects on ionization equilibria: An MNDO study of proton and hydrogen transfer reactions of 4-fluorobutylamine
Authors: Friedl Zdeněk , Böhm Stanislav
Published: February 2010

The relative enthalpies of proton transfer δ ΔH0and homolytic bond strengths δDH0(B-H+) were calculated by the MNDO method for the sp and ap conformers of 4-flurobutylamine. The data obtained, along with the experimental gas phase basicities, are compared with the values predicted by the electrostatic theory. It is shown that the substituent polar effects FD on the basicities of amines are predominantly due to interactions in their protonated forms (X-B-H+) and/or radical-cations (X-B+.), those in the neutral species (X-B) playing a minor part. A contribution, which is considerably more significant in the sp conformer than in the ap conformer, arises probably also from substituent effects on the homolytic bond strength DH0(B-H+.
Thermodynamics of some model reactions useful for understanding theoretical background of correlation analysis
Authors: Slanina Zdeněk
Published: February 2010

Six isodesmic gas-phase reactions have been studied out of which three reactions represent a redistribution of two methyl substituents and the other three represent a redistribution of two chloro substituents between two benzene nuclei. The thermodynamics of these reactions has been evaluated on the basis of the partition functions and observed heats of formation at room temperature. The partition functions have been constructed with the help of observed structural and vibrational data. If the internal rotation was present, the frequence of the corresponding torsional vibrational mode has been determined by a fit to the observed thermodynamic data.The energy characteristic calculated for these reactions (the standard change of Gibbs free energy ΔGT0, enthalpy ΔHT0, enthalpy at absolute zero ΔH00, and potential energy change ΔE) have been evaluated from the standpoint of their applicability to organic correlation analysis. The studies form a part of a wider project, and, in accordance with the findings already presented within this project elsewhere and concerning reactions of fluorobenzenes, they indicate a certain preferred role of the term ΔH00 in these contexts.
Acidity in water (pKa values) of carboxylic acids derived from simple heterocycles (azoles and azines)
Authors: Cativiela Carlos , Dejardin Jean-Louis , Elguero José , Garcia José I. , Gonzalez Emmanuel , Mayoral José A.
Published: February 2010

The pKa of eighteen heterocyclic carboxylic acids derived from thiophene, furan, pyrrole, benzothiophene, benzofuran, indole, pyridine and quinoline have been determined by spectrophotometry and potentiometry. The values thus obtained are discussed using additive models of the Free-Wilson type. Some theoretical calculations within the AM1 approximation have been carried out in order to understand why annelation effects are dependent on the position, α or β, of the carboxylic group. In the case of pyridine and quinoline carboxylic acids, the problem of tautomerism between neutral and zwitterionic forms has been considered.
Infra-red and 35Cl nuclear quadrupole resonance studies of hydrogen bonded adducts of 2-chlorobenzoic acid derivatives
Authors: Kalenik Jerzy , Majerz Irena , Sobczyk Lucjan , Grech Eugeniusz , Habeeb Mustafa M. M.
Published: February 2010

The IR and 35Cl NQR spectra of several solid hydrogen bonded adducts of o-chlorobenzoic acids and amines were studied over the broad ΔpKa range. Both IR and NQR spectra yield the indication of the existence of an inversion (critical) ΔpKa range where the proton transfer takes place. The critical point is distinguished by a deep minimum of the position of the gravity centre of the broad protonic band. The mechanism of the transmittance of the charge distribution within the hydrogen bridge on the electric field gradient in the position of quadrupole Cl nuclei attached to the phenyl ring is analysed.
Information gain as uncertainty reduction
Authors: Eckschlager Karel
Published: February 2010

It is shown that the various information content or information gain measures can be expressed in terms of the difference between the a priori and a posteriori uncertainties. Measures based on uncertainty expressed by means of variance are compared with those where the uncertainty also involves bias of the results, and it is shown that measures of the two kinds somewhat different application.
Solvent effects on kinetics and mechanism of acid-catalyzed decomposition of 1,3-bis(4-methylphenyl)-triazene II. Reactions in aprotic solvents
Authors: Pytela Oldřich , Nevěčná Taťjana , Ludwig Miroslav
Published: February 2010

The effect of aprotic solvents (hexane, cyclohexane, dichloromethane, 1,2-dichloroethane, benzene, acetonitrile, acetone, 1,2-dimethoxyethane, ethyl acetate, dioxane) on kinetics and mechanism of acid-catalyzed decomposition of 1,3-bis(4-methylphenyl)triazene has been studied with trichloroacetic acid as the acid catalyst. It has been found that beside the non-dissociated monomer of the acid also its dimer acts as the catalytic species. With regard to the results obtained in protic solvents (the catalysis by proton and general acid) three cases can be encountered of the dependence of observed rate constant on analytical concentration of the acid. The effect of solvents (inclusive of the protic ones) on the catalytic rate constant of the reaction with the non-dissociated monomer of acid is best interpreted by the equation suggested by Koppel and Palm and by the solvent scale suggested by us earlier. The solvent acidity and polarity have positive effect, whereas its basicity has negative effect. The catalytic rate constant of the reaction with the acid dimer decreases with increasing solvent basicity and polarity, due predominantly to the decrease in the equilibrium constant of dimerization.