bluuebunny/crossref_metadata_2025 huggingface dataset:
A Lie algebraic approach to Ricci flow invariant curvature conditions and Harnack inequalities
Authors: Wilking Burkhard
Published: March 2012

We consider a subset S of the complex Lie algebra 𝔰𝔬﻿(n, ℂ) and the cone C﻿(S) of curvature operators which are nonnegative on S. We show that C﻿(S) defines a Ricci flow invariant curvature condition if S is invariant under AdSO﻿(n, ℂ). The analogue for Kähler curvature operators holds as well. Although the proof is very simple and short, it recovers all previously known invariant nonnegativity conditions. As an application we reprove that a compact Kähler manifold with positive orthogonal bisectional curvature evolves to a manifold with positive bisectional curvature and is thus biholomorphic to ℂℙn. Moreover, the methods can also be applied to prove Harnack inequalities.
The aryl hydrocarbon receptor system
Authors: Barouki Robert , Aggerbeck Martine , Aggerbeck Lawrence , Coumoul Xavier
Published: March 2012

The aryl hydrocarbon receptor (AhR) recognizes a large number of xenobiotics, such as polyaromatic hydrocarbons (PAHs) and dioxins, and it activates several metabolic and detoxification pathways. Recent evidence suggests that this receptor also has important endogenous functions subsequent to activation by natural dietary compounds and/or endogenous metabolites. This receptor, thus, has physiological functions that extend beyond specific instances of detoxification. Understanding the roles played by this receptor might be enhanced by a systems biology approach. Indeed, the AhR “ligandome” is very complex and the different classes of ligands involved could induce widely diverse effects. The protein “interactome” of the AhR comprises several tens of proteins and it is altered by the binding of ligands to the receptor. Furthermore, large-scale studies have shown cell and tissue-specific patterns of regulated gene expression which may depend upon the type of ligand, although these aspects need further substantiation. Finally, the AhR biological effects are extensive and include detoxification, cellular proliferation and migration, immune regulation and neuronal effects. A holistic approach should provide a better understanding of the biology of this receptor in addition to providing new avenues for the identification of specific toxicity mechanisms.
Herb-drug interactions with Danshen (Salvia miltiorrhiza): a review on the role of cytochrome P450 enzymes
Authors: Zhou Xuelin , Chan Kelvin , Yeung John H.K.
Published: March 2012

Danshen, the dried root and rhizome of Salvia miltiorrhiza Bunge, is a widely used medicinal plant for the treatment of cardiovascular diseases in China and a complementary medicine in the West. Danshen is indexed in the 2010 Chinese
Pharmacopoeia, with more than 35 formulations and concoctions containing Danshen water-extracts, ethanolic extracts or their combination, which are rich in phenolic acids and different levels of tanshinones. There are rare reports on the adverse effects of Danshen preparations. It is, however, well-known that Danshen leads the anticoagulation failure of warfarin. The Danshen-warfarin interaction may be mediated via both pharmacodynamic and pharmacokinetic mechanisms. This review does not summarize recent progress, but the effects of Danshen and its active ingredients on the interactions of cytochrome P450 (CYP450) and drug transporters, as well as the analysis of ingredients, and the metabolism and pharmacokinetics that are related to these interactions. Tanshinones play significant roles in the inhibition and induction of several CYP450 isozymes. It can be concluded that precautions should be taken when using Danshen preparations rich in tanshinones for CYP-related herb-drug interactions.
Cytochrome P450 enzymes
Authors: Meyer Urs A.
Published: March 2012

No abstract available.
Characterisation of moisture-dependent plasticity of beech wood and its application to a multi-surface plasticity model
Authors: Hering Stefan , Saft Susanne , Resch Eckart , Niemz Peter , Kaliske Michael
Published: March 2012

The moisture-dependent stress-strain behaviour of European beech wood (Fagus sylvatica L.) has been determined under compression, analytically described for the radial and tangential direction using a modified Ramberg-Osgood approach and realized numerically by a multi-surface plasticity model. The conspicuous decrease of the stress-strain characteristic perpendicular to the grain with increasing moisture content is similar to the behaviour of the presented ultimate strength values in the longitudinal direction. Based on input parameters previously quantified by means of an inverse finite element analysis, the simulation of a crosswise laminated two-layer arrangement during moistening was carried out. A distinct development of plastified regions can be observed due to the resulting swelling stresses.
At the cutting edge: applications and perspectives of laser nanosurgery in cell biology
Authors: Ronchi Paolo , Terjung Stefan , Pepperkok Rainer
Published: March 2012

Laser-mediated nanosurgery has become popular in the last decade because of the previously unexplored possibility of ablating biological material inside living cells with sub-micrometer precision. A number of publications have shown the potential applications of this technique, ranging from the dissection of sub-cellular structures to surgical ablations of whole cells or tissues in model systems such as Drosophila melanogaster or Danio rerio. In parallel, the recent development of micropatterning techniques has given cell biologists the possibility to shape cells and reproducibly organize the intracellular space. The integration of these two techniques has only recently started yet their combination has proven to be very interesting. The aim of this review is to present recent applications of laser nanosurgery in cell biology and to discuss the possible developments of this approach, particularly in combination with micropattern-mediated endomembrane organization.
Disorder-function relationships for the cell cycle regulatory proteins p21 and p27
Authors: Mitrea Diana M. , Yoon Mi-Kyung , Ou Li , Kriwacki Richard W.
Published: March 2012

The classic structure-function paradigm has been challenged by a recently identified class of proteins: intrinsically disordered proteins (IDPs). Despite their lack of stable secondary or tertiary structure, IDPs are prevalent in all forms of life and perform myriad cellular functions, including signaling and regulation. Importantly, disruption of IDP homeostasis is associated with numerous human diseases, including cancer and neurodegeneration. Despite wide recognition of IDPs, the molecular mechanisms underlying their functions are not fully understood. Here we review the structural features and disorder-function relationships for p21 and p27, two cyclin-dependent kinase (Cdk) regulators involved in controlling cell division and fate. Studies of p21 bound to Cdk2/cyclin A revealed that a helix stretching mechanism mediates binding promiscuity. Further, investigations of Tyr88-phosphorylated p27 identified a signaling conduit that controls cell division and is disrupted in certain cancers. These mechanisms rely upon a balance between nascent structure in the free state, induced folding upon binding, and persistent flexibility within functional complexes. Although these disorder-function relationships are likely to be recapitulated in other IDPs, it is also likely that the vocabulary of their mechanisms is much more extensive than is currently understood. Further study of the physical properties of IDPs and elucidation of their links with function are needed to fully understand the mechanistic language of IDPs.
A Note on the Minimal Number of Representations in
Authors: Radziejewska Mirosława
Published: March 2012

Let
On the Problem of Molluzzo for the Modulus 4
Authors: Chappelon Jonathan , Eliahou Shalom
Published: March 2012

We solve the currently smallest open case in the 1976 problem of Molluzzo on
On Abelian and Additive Complexity in Infinite Words
Authors: Ardal Hayri , Brown Tom , Jungić Veselin , Sahasrabudhe Julian
Published: March 2012

The study of the structure of infinite words having
Sinnvolle Diagnostik bei Besonderheiten der Geschlechtsentwicklung/Reasonable diagnostic pathways in disorders of sex development
Authors: Hiort Olaf
Published: March 2012

Besonderheiten der Geschlechtsentwicklung beschreiben eine sehr heterogene Gruppe angeborener Abweichungen der geschlechtlichen Determinierung und Differenzierung, die auch als „Disorders of Sex Development“ oder DSD bezeichnet werden. Hierzu gehören sowohl chromosomale als auch monogen vererbte Störungen, die entweder primär genetisch oder aber hormonell zu einer Abweichung der normalen Geschlechtsentwicklung führen. Laboruntersuchungen können einen wesentlichen Beitrag zur exakten Diagnosestellung leisten. Dabei ist unbedingt auf besondere Bestimmungsmethoden mit ihren zugehörigen alters- und geschlechtsbezogenen Referenzintervallen zu achten. Daher sollte die Beurteilung in einem spezialisierten Zentrum im Kontext mit den klinischen und bildgebenden Befunden erfolgen. Weiterführend sind dann zielgerichtet molekulargenetische Untersuchungen möglich. Bei einem Großteil der Fälle ist heute noch keine genaue kausale Zuordnung möglich. Deshalb ist sowohl zur Diagnosestellung als auch zur Entscheidungsfindung und damit letztendlich für therapeutische Überlegungen ein hochspezialisiertes Team aus Ärzten verschiedenster Fachrichtungen sowie psychosozialen Experten notwendig, um die Eltern und Betroffenen beraten zu können.
Experimental validation of image contrast correlation between ultra-small-angle X-ray scattering and grating-based dark-field imaging using a laser-driven compact X-ray source
Authors: Bech Martin , Schleede Simone , Potdevin Guillaume , Achterhold Klaus , Bunk Oliver , Jensen Torben H. , Loewen Rod , Ruth Ron , Pfeiffer Franz
Published: March 2012

X-ray phase and dark-field contrast have recently been the source of much attention in the field of X-ray imaging, as they both contribute new imaging signals based on physical principles that differ from conventional X-ray imaging. With a so-called Talbot grating interferometer, both phase-contrast and dark-field images are obtained simultaneously with the conventional attenuation-based X-ray image, providing three complementary image modalities that are intrinsically registered. Whereas the physical contrast mechanisms behind attenuation and phase contrast are well understood, a formalism to describe the dark-field signal is still in progress. In this article, we report on correlative experimental results obtained with a grating interferometer and with small-angle X-ray scattering. Furthermore, we use a proposed model to quantitatively describe the results, which could be of great importance for future clinical and biomedical applications of grating-based X-ray imaging.
Synthesis of well-defined clay encapsulated poly(styrene-co-butyl acrylate) nanocomposite latexes via reverse atom transfer radical polymerization in miniemulsion
Authors: Khezri Khezrollah , Haddadi-Asl Vahid , Roghani-Mamaqani Hossein , Salami-Kalajahi Mehdi
Published: March 2012

Well-defined poly(styrene-co-butyl acrylate) nanocomposite latexes were synthesized via reverse atom transfer radical polymerization (RATRP) in miniemulsion. Successful RATRP was carried out by using a hydrophobic ligand of 4,4’-dinonyl-2,2’-bipyridine (dNbpy) and a cationic surfactant of cetyltrimethylammonium bromide (CTAB). Dynamic light scattering (DLS) results show that droplets and particles with sizes in the range of about 170 nm were formed. Overall, conversion and molecular weight evaluation were performed by using gravimetry and size exclusion chromatography (SEC), respectively. Increasing nanoclay loading resulted in an increase in the conversion and molecular weight of the nanocomposites. However, polydispersity index (PDI) values increased by adding nanoclay content. Thermal stability of all the nanocomposites improved in comparison with the neat copolymer, according to the thermogravimetric analysis (TGA) results. Differential scanning calorimetry (DSC) results showed that the glass transition temperature (Tg) increased by increasing nanoclay content. Scanning electron microscopy (SEM) images of the nanocomposite with 1 wt% of nanoclay showed a monodisperse distribution of spherical particles, with sizes in the range of approximately 170 nm, as confirmed by the DLS data. Similarly, transmission electron microscopy (TEM) images show that clay layers are delaminated and well dispersed in the matrix of nanocomposite with 1 wt% clay content.
Perceptual Inference Predicts Contextual Modulations of Sensory Responses
Authors: Lochmann Timm , Ernst Udo A. , Denève Sophie
Published: March 2012

Sensory receptive fields (RFs) vary as a function of stimulus properties and measurement methods. Previous stimuli or surrounding stimuli facilitate, suppress, or change the selectivity of sensory neurons' responses. Here, we propose that these spatiotemporal contextual dependencies are signatures of efficient perceptual inference and can be explained by a single neural mechanism, input targeted divisive inhibition. To respond both selectively and reliably, sensory neurons should behave as active predictors rather than passive filters. In particular, they should remove input they can predict (“explain away”) from the synaptic inputs to all other neurons. This implies that RFs are constantly and dynamically reshaped by the spatial and temporal context, while the true selectivity of sensory neurons resides in their “predictive field.” This approach motivates a reinvestigation of sensory representations and particularly the role and specificity of surround suppression and adaptation in sensory areas.
Caenorhabditis elegansFlamingo Cadherinfmi-1Regulates GABAergic Neuronal Development
Authors: Najarro Elvis Huarcaya , Wong Lianna , Zhen Mei , Carpio Edgar Pinedo , Goncharov Alexandr , Garriga Gian , Lundquist Erik A. , Jin Yishi , Ackley Brian D.
Published: March 2012

In a genetic screen for regulators of synaptic morphology, we identified the singleCaenorhabditis elegansflamingo-like cadherinfmi-1. Thefmi-1mutants exhibit defective axon pathfinding, reduced synapse number, aberrant synapse size and morphology, as well as an abnormal accumulation of synaptic vesicles at nonsynaptic regions. Although FMI-1 is primarily expressed in the nervous system, it is not expressed in the ventral D-type (VD) GABAergic motorneurons, which are defective infmi-1mutants. The axon and synaptic defects of VD neurons could be rescued whenfmi-1was expressed exclusively in non-VD neighboring neurons, suggesting a cell nonautonomous action of FMI-1. FMI-1 protein that lacked its intracellular domain still retained its ability to rescue the vesicle accumulation defects of GABAergic motorneurons, indicating that the extracellular domain was sufficient for this function of FMI-1 in GABAergic neuromuscular junction development. Mutations incdh-4, a Fat-like cadherin, cause similar defects in GABAergic motorneurons. Thecdh-4is expressed by the VD neurons and seems to function in the same genetic pathway asfmi-1to regulate GABAergic neuron development. Thus,fmi-1andcdh-4cadherins might act together to regulate synapse development and axon pathfinding.
Changes in Auditory Feedback Connections Determine the Severity of Speech Processing Deficits after Stroke
Authors: Schofield Thomas M. , Penny Will D. , Stephan Klaas E. , Crinion Jennifer T. , Thompson Alan J. , Price Cathy J. , Leff Alexander P.
Published: March 2012

We compared brain structure and function in two subgroups of 21 stroke patients with either moderate or severe chronic speech comprehension impairment. Both groups had damage to the supratemporal plane; however, the severe group suffered greater damage to two unimodal auditory areas: primary auditory cortex and the planum temporale. The effects of this damage were investigated using fMRI while patients listened to speech and speech-like sounds. Pronounced changes in connectivity were found in both groups in undamaged parts of the auditory hierarchy. Compared to controls, moderate patients had significantly stronger feedback connections from planum temporale to primary auditory cortex bilaterally, while in severe patients this connection was significantly weaker in the undamaged right hemisphere. This suggests that predictive feedback mechanisms compensate in moderately affected patients but not in severely affected patients. The key pathomechanism in humans with persistent speech comprehension impairments may be impaired feedback connectivity to unimodal auditory areas.
Targeted Deletion of ERK5 MAP Kinase in the Developing Nervous System Impairs Development of GABAergic Interneurons in the Main Olfactory Bulb and Behavioral Discrimination between Structurally Similar Odorants
Authors: Zou Junhui , Pan Yung-Wei , Wang Zhenshan , Chang Shih-Yu , Wang Wenbin , Wang Xin , Tournier Cathy , Storm Daniel R. , Xia Zhengui
Published: March 2012

ERK5 MAP kinase is highly expressed in the developing nervous system and has been implicated in promoting the survival of immature neurons in culture. However, its role in the development and function of the mammalian nervous system has not been establishedin vivo. Here, we report that conditional deletion of theerk5gene in mouse neural stem cells during development reduces the number of GABAergic interneurons in the main olfactory bulb (OB). Our data suggest that this is due to a decrease in proliferation and an increase in apoptosis in the subventricular zone and rostral migratory stream of ERK5 mutant mice. Interestingly, ERK5 mutant mice have smaller OB and are impaired in odor discrimination between structurally similar odorants. We conclude that ERK5 is a novel signaling pathway regulating developmental OB neurogenesis and olfactory behavior.
Materials for deep blue organic light emitting devices with ultra high thermal stability and charge mobility
Authors: Kwon Soonnam , Wee Kyung R. , Kang Sang O.
Published: March 2012

The development of materials with high stability and high charge mobility is urgent for commercial application of blue phosphorescent organic light emitting devices (PHOLED). Silicon based inorganic-organic hybrid materials with ultra high glass transition temperature (over 150 °C) and high charge mobility (over 1.16 x 10-3 at 5 x 105 V/cm) were synthesized. These showed high external quantum efficiency of over 19%, and deep blue color coordinates of (0.15, 0.23), when they were used as a host materials in the PHOLED.

The origin of the above interesting properties was investigated by experimental measurements complemented by DFT calculations. Estimations of the structure-property relationship of a molecule in an amorphous thin film would be presented
Effects of Substituted Side Chains on the Optical and Electrical Properties of D-A Conjugated Copolymers
Authors: Cho Shinuk , Lee Sangkyu , Tong Minghong , Seo Jung Hwa , Heeger Alan J.
Published: March 2012

The effects of substitute side chain were investigated using donor-acceptor (D-A) conjugated copolymers consisting of a cyclopentadithiophene (CPDT) derivative and dithienyl-benzothiadiazole (DTBT). The intrinsic properties of the copolymers were significantly altered by perturbations of the intramolecular charge transfer (ICT). The absorption of PCPDT-ttOTBTOT (P2), which assumed a tail-tail configuration, tended to blue-shift relative to the absorption of PCPDT-TBTT (P1). The absorption of PCPDT-hhOTBTOT (P3), which assumed a head-head configuration, was blue-shifted relative to that of P2. The electrical transport properties of field-effect transistors (FETs) were sensitive to the side chain position. The field-effect mobility in P2 (μ2=1.8×10–3 cm2/V·s) was slightly lower that in P1 (μ1=4.9×10–3 cm2/V·s). The mobility of P3, however, was very low (μ3=3.8×10–6 cm2/V·s). Photoexcitation spectroscopy showed that the charge generation efficiency (shown in transient absorption spectra) and polaron pair mobility in P1 and P2 were higher than in P3, yielding P1 and P2 device performances that were better than the performance of devices based on P3.
Evaluating the Potential for Differential Susceptibility of Common Reed (Phragmites australis) Haplotypes I and M to Aquatic Herbicides
Authors: Cheshier Joshua C. , Madsen John D. , Wersal Ryan M. , Gerard Patrick D. , Welch Mark E.
Published: March 2012

Common reed (Phragmites australis) is an invasive perennial grass in aquatic and riparian environments across the United States, forming monotypic stands that displace native vegetation that provides food and cover for wildlife. Genetic variation in global populations of common reed has given rise to two invasive haplotypes, I and M, in the United States. Our objectives were to (1) determine if any differences in herbicide efficacy exist with respect to common reed haplotypes I and M and (2) screen for other labeled aquatic herbicides that may have activity on common reed haplotypes I and M, most notably imazamox and diquat. A replicated outdoor mesocosm study was conducted in 1,136-L (300-gal) tanks using haplotypes I and M of common reed. Restriction fragment length polymorphism methodologies were used to verify the identification of I and M haplotypes used in this study. Diquat at 2.2 (1.9) and 4.5 (4.0) kg ai ha−1 (lb ai ac−1), glyphosate at 2.1 (1.8) and 4.2 (3.7) kg ae ha−1 (lb ae ac−1), imazamox at 0.6 (0.5) and 1.1 (0.9) kg ai ha−1 (lb ai ac−1), imazapyr at 0.8 (0.7) and 1.7 (1.5) kg ai ha−1 (lb ai ac−1), and triclopyr at 3.4 (3.0) and 6.7 (5.9) kg ae ha−1 (lb ae ac−1) were applied to the foliage of common reed. After 12 wk, no difference (P = 0.28) in herbicide tolerance was seen between the two haplotypes with respect to biomass. The 4.2-kg ae ha−1 rate of glyphosate and the 0.8- and 1.7 kg ai ha−1 rates of imazapyr reduced common reed by > 90% at 12 wk after treatment (WAT). Imazamox at 0.6 and 1.1 kg ai ha−1, and triclopyr at 3.4 and 6.7 kg ae ha−1 reduced common reed biomass (62–86%) at 12 WAT, though regrowth occurred. Diquat did not significantly reduce biomass by 12 wk. Glyphosate and imazapyr were the only herbicides that resulted in > 90% biomass reduction and corroborate control from previous studies.
Flexural fatigue analysis of hybrid fibre-reinforced concrete
Authors: Bajaj Vineet , Singh Surinder Pal , Singh Amrit Pal , Kaushik Surendra Kumar
Published: March 2012

This paper presents the results of an investigation conducted to examine the probability distributions and flexural fatigue performance of hybrid fibre-reinforced concrete (HyFRC) containing different proportions of steel and polypropylene fibre. An experimental programme was planned to obtain the fatigue lives of HyFRC, in which approximately 435 beam specimens of size 100 × 100 × 500 mm were tested under four-point flexural loading. Approximately 225 static flexural strength tests were also conducted to facilitate fatigue testing. The specimens incorporated different proportions of steel and polypropylene fibres in the ratio of 25:75%, 50:50% and 75:25% by volume at each fibre volume fraction of 0·5%, 1·0% and 1·5%. The fatigue test data were used to establish probability distributions of HyFRC at different stress levels. The gradual replacement of steel fibres by polypropylene fibres in the HyFRC mix was found to significantly reduce the variability in the distribution of fatigue life of HyFRC compared with steel fibre-reinforced concrete containing comparable mono steel fibres in terms of size and shape. To examine the flexural fatigue performance of HyFRC, the test results are presented in the form of S–N diagrams; two million cycles of fatigue strengths/endurance limits were determined for different fibre mix combinations corresponding to each fibre volume fraction. The test results indicate that a combination of 50% steel fibres and 50% polypropylene fibres is the most appropriate for both reduction in variability and flexural fatigue performance in terms of the two-million cycle fatigue strength/endurance limit of HyFRC.
The sustainability of new urban developments in Dubai
Authors: Hadjri Karim , Onyango John
Published: March 2012

Dubai, the second largest city of the United Arab Emirates, is a fast-growing hub with increasing need for infrastructure, housing and public facilities. Dubai is trying to market itself as an attractive holiday destination, and has seen the launching and building of large-scale planned communities, some of which are located on reclaimed land along the city's coast line. This paper reviews Dubai's green building agenda by examining the scale and typologies of new and planned low-carbon projects, and discusses the potential of renewable sources of energy that can reduce the country's dependence on fossil fuels and improve long-term sustainability. The potentials of solar energy, wind power and geo-thermal energy in Dubai and the United Arab Emirates in general are assessed.
Short‐Term Effect of Cyclosporin Injections on Experimental Gingival Inflammation in the Rat
Authors: Hemmerle Joseph , Frank Robert M.
Published: March 2012

Experimental gingivitis was induced in 2 groups of 10 adult Wistar rats by feeding them a high sucrose diet for 30 days. Since cyclosporin has an immunosuppressive effect on the stimulation of T lymphocytes, the test group received 5 intraperitoneal injections of cyclosporin A from day 20 to 30 while the control group received no additional treatment. The gingival regions of the molars were studied in light and transmission electron microscopy. In both groups, a well‐differentiated wall of polymorphonuclear neutrophils (PMNs) was present between the dental plaque and the papillary epithelium and no bacterial invasion occurred despite the local absence of T lymphocytes in the test group. It can be concluded that T lymphocytes are not involved in the mechanism of bacterial invasion. J Periodontol 1993; 64:24–28.
Periodontal Microflora of HIV Positive Subjects With Gingivitis or Adult Periodontitis
Authors: Moore Lillian V.H. , Moore W.E.C. , Riley Chiara , Brooks C.N. , Burmeister J.A. , Smibert R.M.
Published: March 2012

The subgingival microflora of 39 HIV + subjects with gingivitis or adult Periodontitis was cultured quantitatively anaerobically for bacteria, spirochetes, and mycoplasma and aerobically for yeasts. Isolates were characterized by conventional biochemical tests, Polyacrylamide gel electrophoresis of soluble proteins, cellular fatty acid profiles, immunofluorescence, and immunodiffusion. In general, the same types of bacteria were isolated from the subgingival crevice of HIV + subjects as we previously had isolated from the subgingival crevice of non‐HIV subjects. A statistically significant difference was found between the composition of the flora of HIV + subjects with adult Periodontitis (AP) and concurrent studies of a non‐HIV + AP population. Mycoplasma salivarium was significantly elevated in the HIV+ subjects examined. Yeasts were isolated from only 10% of the samples and from 13% of the HIV‐positive subjects at 0.05 to 0.0002% of the total cultivable count when present. J Periodontol 1993; 64:48–56.
Treatment of the Palato‐Gingival Groove With Guided Tissue Regeneration. Report of 10 Cases
Authors: Anderegg Charles R. , Metzler David G.
Published: March 2012

The purpose of this study is to demonstrate the potential of using a barrier in the treatment of palato‐gingival groove defects. The study group consisted of 10 patients. Prior to treatment, the palato‐gingival groove on maxillary lateral incisors was measured with calibrated periodontal probe from the cemento‐enamel junction (CEJ) to the free gingival margin (FGM) and from the FGM to the base of the pocket (BP). Probing depth (PD) was calculated and bleeding on probing indicated. Surgical procedures consisted of flap reflection, removal of granulation tissue, and scaling and root planing of the groove. An expanded polytetrafluoroethylene membrane was sutured over the palato‐gingival groove. Six months postsurgery, all measurements were repeated. Statistical analysis compared results using means, standard deviations, and paired t tests. Results showed an improvement in clinical attachment gain, probing depth reduction, and decreased bleeding on probing. This study demonstrates the potential of guided tissue regeneration in the treatment of palato‐gingival groove defects. A random blinded clinical trial is necessary, however, to fully assess the potential of this procedure in treatment of palato‐gingival groove defects. J Periodontol 1993; 64:72–74.
A Clinical Comparison of Collagen Membranes With e‐PTFE Membranes in the Treatment of Human Mandibular Buccal Class II Furcation Defects
Authors: Blumenthal Neil M.
Published: March 2012

Guided tissue regeneration procedures using non‐resorbable expanded polytetrafluoroethylene (e‐PTFE) membranes have become accepted therapy in treating moderate furcation defects. Resorbable collagen membranes have also been found to support regeneration and preclude the need for surgical removal. The present study compares their effectiveness with e‐PTFE membranes in treating human mandibular Class II buccal furcation defects over a 12‐month healing interval. Twelve patients were treated with collagen membrane in one defect and e‐PTFE in another. Vertical and horizontal defect repair was evaluated through soft tissue probings and hard tissue measurements. Gingival indices and crevicular fluid flow measurements were used to evaluate site inflammation. Intragroup comparisons were made from baseline to 12 months for each type of membrane (sign test) and for differences between treatment groups with collagen versus e‐PTFE membranes (Wilcoxon signed rank test). Both materials were effective in gaining vertical open probing new attachment and horizontal open and closed probing new attachment. Collagen membrane was statistically superior to e‐PTFE in gaining horizontal open new probing attachment and in reduced levels of inflammation at the surgical site from baseline to 4 weeks. However, clinical differences were negligible. The intrinsic properties and ease of handling make collagen membranes a feasible alternative in guided tissue regeneration procedures. J Periodontol 1993; 64:925–933.
Radiographic Attachment in Periodontitis–Prone Teeth With Endodontic Infection
Authors: Janssen Leif E. , Ehnevid Helge , Lindskog Sven F. , Blomlöf Leif B.
Published: March 2012

The purpose of the present investigation was to examine the influence of a root canal infection on radiographic attachment. In addition, influence of the quality of the root fillings as well as the size of the periapical radiolucencies were studied. The investigation was conducted as a retrospective study on a consecutive referral population. The periapical conditions in endodontically‐involved single‐rooted teeth from a selected patient sample were correlated to the periodontal status of the teeth. Teeth with periapical lesions were found to have lost significantly more radiographic attachment, approximately 2 mm. A comparison between pocket depth in teeth with and without periapical pathology consistently showed that periapical pathology was significantly correlated to an increased pocket depth, also after adjusting for differences in radiographic attachment. It was concluded that periodontitis‐prone teeth run a significantly higher risk of losing periodontal attachment if a root canal infection is also present and evident as a periapical radiolucency. J Periodontol 1993;64:947–953.
Evaluating Patient Perceptions as Short‐Term Outcomes of Periodontal Treatment: A Comparison of Surgical and Non‐Surgical Therapy
Authors: Matthews Debora C. , McCulloch Christopher A. G.
Published: March 2012

To quantify patient perceptions of periodontal therapy, we administered a self‐report questionnaire employing a visual analog scale (VAS) to 162 patients following surgical and non‐surgical treatments. The questionnaire tested for variables of pain, sensitivity, swelling, function, altered appearance, comparison of postoperative discomfort to restorative treatment (crown or filling), discomfort experienced during the procedure, and resultant disability days. Tests of reliability indicated that with the exception of thermal sensitivity, the variables were significantly reproducible (r> 0.45 for all tests, P < 0.002). Analyses of variance indicated that in contrast to non‐surgical treatments, surgery produced significantly more postoperative “discomfort” (P < 0.05) for all variables except experience, sensitivity, altered speech, and comparison to crown preparation. When analyzed according to the type of procedure, soft tissue grafts and osseous surgery produced the most postoperative discomfort. Pearson correlation indicated statistically significant (P <.0001) relationships between pain‐related measures (postoperative pain, number of postoperative analgesics, days of pain, days of work missed, and sensitivity). Duration of pain was also found to be related to a history of periodontal treatment (P <.02), but not to previous restorative treatment. These data indicate that patient perceptions of periodontal treatment can be reliably measured and may be used to address appropriateness of care issues. J Periodontol 1993; 64:990–997.
Effects of a Combination Therapy to Eliminate Porphyromonas gingivalis in Refractory Periodontitis
Authors: Collins John G. , Offenbacher Steven , Arnold Roland R.
Published: March 2012

This report describes the clinical and microbiological features of 30 refractory patients and their response to a combined local and systemic therapy at 6 weeks and 3 years following treatment. The refractory treatment protocol (RefTx) consisted of a 2week regimen of amoxicillin/clavulanate potassium in conjunction with professional, intrasulcular delivery of povidone iodine, and chlorhexide mouthwash rinses b.i.d. Eightyseven percent of the patients had favorable clinical responses to the RefTx and could be divided into 3 groups (A, B, C) based upon initial flora patterns and the shifts that occurred following treatment. Pretreatment prevalence of Porphyromonas gingivalis (P.g.) was 36.7%. The RefTx was effective in reducing P.g. below detection levels in 10 of the 11 positive patients at P <0.01; each of these 10 patients (Group A) demonstrated significant gain in attachment. Other black‐pigmented Bacteroides species (OBP) were isolated from 70% of the patients at baseline. Nine of these patients did not harbor P.g., showed clinical improvement upon treatment, and were OBP negative following treatment (Group B). Group C patients (7) demonstrated clinical improvement with therapy and did not fit into either Group A or B based upon microbial patterns. Group D patients (4) did not show clinical improvement with 3 patients harboring either P.g. or OBP after treatment. The RefTx was effective at reducing probing pocket depth with a 56% decrease in the number of pockets greater than 6 mm at 6 weeks. This was accompanied by an overall gain of ≥1 mm of probeable attachment in 45% of all sites. The clinical effects of the RefTx were shown to persist at 34.3 months with an apparent attachment gain of ≥1 mm in 41.2% of sites. These data suggest that P.g. and OBP are important pathogens in refractory periodontitis and that the RefTx protocol is an acceptable, non‐invasive alternative for the management of these patients. J Periodontol 1993; 64:998–1007.
Marginal Periodontitis and Cytokines: A Review of the Literature
Authors: Kjeldsen Mette , Holmstrup Palle , Bendtzen Klaus
Published: March 2012

Recent research on the immunopathogenesis of marginal periodontitis has focused on cytokines, because these mediators govern biologicial activities in inflammatory tissue destruction. Several studies have been carried out to elucidate the involvement of cytokines in periodontitis, including cytokine measurements in samples from gingival tissue, gingival crevicular fluid, and in supernatants of stimulated in vitro grown cells from gingival tissue and peripheral blood. The results, summarized in this review, suggest that cytokines are involved in the progress of periodontitis. Furthermore, cytokines may be valuable as markers of tissue breakdown. At the present stage, however, there are difficulties in detecting and quantifying cytokines by immunochemical methods and, in particular, by bioassays. Increased knowledge of the cytokine network may open new pathways of periodontitis treatment by controlling processes involved in tissue breakdown. J Periodontol 1993;64:1013–1022.
An In Vitro Study of Dentinal Tubule Occlusion by Ferric Oxalate
Authors: Dragolich William E. , Pashley David H. , Brennan William A. , O'Neal Robert B. , Horner Jack A. , Van Dyke Thomas E.
Published: March 2012

This study examined ferric oxalate's ability to occlude dentinal tubules both in the presence of a smear layer and after its removal. Radicular dentinal chips were prepared with a smear layer created from a high speed carbide bur. The dentinal chips were then grouped as follows: 1) those with the smear layer remaining intact; 2) those sonicated for 7 minutes; 3) those treated with 10% tetracycline HCl; 4) those treated with 0.5M EDTA; 5) those treated with 20% citric acid; or 6) those treated with saturated citric acid. Six percent ferric Oxalate was applied for 1 minute to the dentinal chips under blinded conditions. The chips were examined under SEM and the number of small and large crystals formed were counted. The results indicate that a decrease in the number of small crystals occurs following pretreatment of the smear layer by chemical means. An increased variability in size and shape of the crystals is also observed when no chemical pretreatment is used. Thus, relative to the number of crystals that form, no chemical pretreatment of radicular dentin is indicated prior to application of ferric Oxalate in the treatment of root sensitivity. J Periodontol 1993; 64:1045–1051.
Oral Hygiene Status and Necrotizing Ulcerative Gingivitis in Nigerian Children
Authors: Taiwo Juliana O.
Published: March 2012

This study was designed to determine the association between oral hygiene status and necrotizing ulcerative gingivitis (NUG), as well as the severity of NUG in Nigerian children. The study cohort was made up of 438 children under 12 years attending the Dugbe Dental Centre in Ibadan, Nigeria. A dental history and intra‐oral examination using probe and mirror were taken. A slightly modified Green and Vermillion index was used to determine oral hygiene status. An index was also developed for NUG severity. The result showed that only 2.4% of the children with good oral hygiene had NUG, compared with: 24.6% of those with fair oral hygiene; 62.8% of those with poor oral hygiene; and 66.7% of those with very poor oral hygiene. The prevalence of the more severe stages of the disease showed an increasing trend as the oral hygiene status became poorer. This study thus demonstrated that the prevalence of NUG was significantly higher and more severe in children with poor oral hygiene status compared with those having good oral hygiene status. (P < 0.001). J Periodontol 1993:63:1071–1074.
Effects of Sex Hormones on Production of Prostaglandin E2 by Human Peripheral Monocytes
Authors: Miyagi Masaharu , Morishita Masayuki , Iwamoto Yoshifumi
Published: March 2012

The effects of sex hormones on the in vitro production of prostaglandin (PG) E2 by monocytes were investigated. Monocytes were obtained from heparinized peripheral blood of healthy adults and incubated for 24 hours with lipopolysaccharide (LPS) and sex hormones. After incubation, the medium was assayed for PGE2 by means of radioimmunoassay. PGE2 production by monocytes was enhanced by progesterone. Estradiol reduced PGE2 production at 0.4 ng/ml, but enhanced it at 20 ng/ml. Testosterone reduced PGE2 production. The reduced PGE2 production by monocytes treated with 0.4 ng/ml of estradiol was restored to the control level by addition of progesterone at 20 ng/ml. These results suggest that sex hormones may modulate gingival inflammation mediated by PGE2. J Periodontol 1993; 64:1075–1078.
Guided Tissue Regeneration Using Calcium Phosphate Implants Together With 4 Different Membranes. A Study on Furcations in Dogs
Authors: Lekovic Voja , Kenney E. Barrie
Published: March 2012

Four different membranes were used in conjunction with porous calcium phosphate granules to treat grade II furcations in lower molars of 6 dogs. Six months later block sections were used to measure the amount of regeneration and inflammation. The 4 membranes (polycarbonate, silicone rubber, polytetrafluoroethylene, and polycaprolactone) all gave similar improvements in bone fill ranging from 1.74 ± 0.44 mm to 2.02 ± 0.38 mm while control areas had only 0.34 ± 0.12 mm. The amount of new attachment ranged from 2.32 ± 0.62 mm to 2.58 ± 0.62 mm for the membranes and was 0.26 ±0.11 mm for controls. There were increased numbers of chronic inflammatory cells seen with the polycarbonate and polycaprolactone group compared to controls and the other 2 membranes.J Periodontol 1993; 64:1154–1156.
Isolation of Periodontal Species After Guided Tissue Regeneration
Authors: Mombelli Andrea , Lang Niklaus P. , Nyman Sture
Published: March 2012

One advanced localized periodontal lesion in each of 10 patients was treated using the guided tissue regeneration procedure. Six weeks after placement of expanded polytetrafluoroethylene (ePTFE) membranes, microbial samples were taken from each treated site and the membranes were removed. Six weeks later the cases were re‐evaluated. They had all healed successfully with varying amounts of gain of clinical attachment. Gram‐negative, anaerobic rods were found in all samples and made up 31% of all organisms cultivated. In 1 patient, Porphyromonas gingivalis was found in a proportion of 17.5%. Six of the other 9 patients harbored Prevotella intermedia (mean proportion 21.3%) and 6 Prevotella melaninogenica (6.8%). Fusobacterium and Capnocytophaga were also frequently found. The results demonstrate that ePTFE membranes are frequently colonized by periodontal microorganisms. The importance of bacterial colonization on clinical success is presently not known. Further studies are needed to determine the effect of the presence or absence of putative pathogens during guided tissue regeneration. J Periodontol 1993; 64:1171–1175.
Colonization of Retrieved Polytetrafluoroethylene Membranes: Morphological and Microbiological Observations
Authors: Tempro Paulette J. , Nalbandian John
Published: March 2012

Polytetrafluoroethylene membranes (ePTFE) used in guided tissue regeneration (GTR) are accessible to colonization by oral bacteria. The bacterial composition of the adherent biomass is unknown. We examined a total of 6 membranes that were retrieved after 4 to 6 weeks from human periodontitis sites, using optical and transmission electron microscopy (TEM) as well anaerobic cultivation. Five of the 6 membranes provided the microbiological data and microscopic data. TEM revealed an organized microbial mass covering the surfaces and also within the interstices of the open microstructure and occlusive portions of the membranes. Numerous bacterial forms including cocci, rods, and filaments with an interbacterial matrix, frequently in microcolonies, were identified. Anaerobic cultivation yielded Streptococcus and Actinomyces species with a minor component of Gram‐negative facultative rods comprised mainly of Haemophilus species. Candida species was recovered from one membrane. These data show that ePTFE is heavily colonized by oral bacteria during retention. The impact of bacterial colonization of ePTFE is not known but it seems reasonable to assume that colonization of membranes may affect connective tissue regeneration. Further studies will be needed to examine the effect of systemic antimicrobials on ePTFE colonization and in turn to examine the effect on GTR. J Periodontol 1993;64:162–168.
Time‐Related Changes of In Vivo Projection Errors in Standardized Radiographs
Authors: Zappa Urs , Simona Claudio , Graf Hans , van Aken Jan
Published: March 2012

Subtraction radiography requires radiographs made with identical projection geometry. Recently a new radiographic aiming device and an x‐ray beam manipulator made it possible to repeat radiographic exposures in vivo with small angular errors and to measure the angular errors occurring. The purpose of the present investigation was to study in vivo the measuring error and the angular errors produced by this new method at different time points (0, 6, and 12 months) and to assess the effect of different time intervals between exposures (0, 6, and 12 months). Ten sites were investigated. At each time point 2 exposures were made, resulting in 6 radiographs per site. For each pair of radiographs the measuring errors occurring during analysis and the projection errors were determined for each time point and for each time interval. Friedman's test and t‐test were used to evaluate the errors. A difference in the measuring error of the system and in the angular errors at the timepoints 0, 6, and 12 months could not be detected. A time interval between exposures also did not have an effect on the measuring error. Time did not affect the vertical and horizontal angular errors measured between the radiographs producing the smallest oblique error. A combination of radiographs producing the largest oblique angular error showed an increase of the horizontal and vertical angular errors when the time interval increases. These effects, however, were not statistically significant. From these results it appears that the new radiographic aiming device and x‐ray beam manipulator produce radiographs with small changes in angular projection errors between radiographs taken with a time interval of 0, 6, or 12 months when they are selected from duplicate exposures. This new radiographic aiming device and x‐ray beam manipulator will greatly assist in providing standardized radiographs for computer analysis of changes in alveolar bone over time. J Periodontol 1993; 64:278–284.
A Light Microscopy, Scanning Electron Microscopy, and Laser Scanning Microscopy Analysis of Retrieved Blade Implants After 7 to 20 Years of Clinical Function. A Report of 3 Cases
Authors: Trisi Paolo , Quaranta Manlio , Emanuelli Mario , Piattelli Adriano
Published: March 2012

The aim of the present study was to evaluate by means of light microscopy, scanning electron microscopy, and laser scanning microscopy the thin ground sections of blade implants retrieved after 7 to 20 years of clinical function. Microscopic examination revealed that most of the implant surface had an intimate contact with compact lamellar bone tissue. Higher magnifications revealed the presence of a gap (1 to 5μ) interposed between bone and implant. Many osteocytes were near the implant surface and, in many instances, osteocyte canaliculi, running from the lacunae towards the implant surface, were seen. Structures similar to bone reversal lines were observed at the edge of the bone side of the interface. The bone‐titanium region is probably an area of dynamic biological activity. J Periodontol 1993; 64:374–378.