bluuebunny/crossref_metadata_2025 huggingface dataset:
Endocrinology of protochordates
Authors: Sherwood Nancy M , Adams Bruce A , Tello Javier A
Published: April 2005

Large-scale gene duplications occurred early in the vertebrate lineage after the split with protochordates. Thus, protochordate hormones and their receptors, transcription factors, and signaling pathways may be the foundation for the endocrine system in vertebrates. A number of hormones have been identified including cionin, a likely ancestor of cholecytokinin (CCK) and gastrin. Both insulin and insulin-like growth hormone (IGF) have been identified in separate cDNAs in a tunicate, whereas only a single insulin-like peptide was found in amphioxus. In tunicates, nine distinct forms of gonadotropin-releasing hormone (GnRH) are shown to induce gamete release, even though a pituitary gland and sex steroids are lacking. In both tunicates and amphioxus, there is evidence of some components of a thyroid system, but the lack of a sequenced genome for amphioxus has slowed progress in the structural identification of its hormones. Immunocytochemistry has been used to tentatively identify a number of hormones in protochordates, but structural and functional studies are needed. For receptors, protochordates have many vertebrate homologs of nuclear receptors, such as the thyroid, retinoic acid, and retinoid X receptors. Also, tunicates have cell surface receptors including the G-protein-coupled type, such as β-adrenergic, putative endocannabinoid, cionin (CCK-like), and two GnRH receptors. Several tyrosine kinase receptors include two epidermal growth factor (EGF) receptors (tunicates) and an insulin/IGF receptor (amphioxus). Interestingly, neither steroid receptors nor a full complement of enzymes for synthesis of sex steroids are encoded in the Ciona genome. Tunicates appear to have some but not all of the necessary molecules to develop a vertebrate-like pituitary or complete thyroid system.
SIMPLIFIED ANALYTICAL EXPRESSION FOR CALCULATING NOISE FIGURE OF HEMT GATE MIXERS
Authors: AMROUCHE F. , ALLAM R. , DASCALESCU L.
Published: April 2005

A simplified analytical expression for calculating noise figure of HEMT gate mixers is presented based on superposition method. The contributions of each noise source have been presented. The non-linear behavior of the transistor expressed by the transconductance profile is used to evaluate the noise figure versus LO power. This study is applied to a HEMT gate mixer, tested at 28.5 GHz radio frequency and 4 GHz intermediate frequency. The predicted and the measured noise figures are in good agreement.
MULTIMARKET MINORITY GAME
Authors: PŁATKOWSKI TADEUSZ , RAMSZA MICHAŁ
Published: April 2005

We consider a system of heterogeneous agents playing the Minority Game on two markets. At each time step, each agent plays on one of the markets only. The agents can change the market according to some switching scheme. Various switching schemes are investigated: those that depend on the performance of the agents on each of the markets, and those that determine the actual market as a function of the number of games lost on the markets. We discuss the influence of the chosen switching scheme on the overall performance of the system of agents. In particular, we study both aggregate attendance (price returns) and volatilities for various schemes of the market choice.
NUMERICAL APPROXIMATION OF THE PERCENTAGE OF ORDER FOR ONE-DIMENSIONAL MAPS
Authors: LIVADIOTIS G.
Published: April 2005

The percentage of organized motion of the chaotic zone (which shall from now on be referred to as percentage of order) for the logistic, the sine-square and the 4-exponent map, is calculated. The calculations are reached via a sampling method that incorporates the Lyapunov exponent. Although these maps are specially selected examples of one-dimensional ones, the conclusions can also be applied to any other one-dimensional map. Since the metric characteristics of a bifurcation diagram of a unimodal map, such as the referred percentage of order, are dependent on the order of the maximum, this dependence is verified for several maps. Once the chaotic zone can be separated into regions between the sequential band mergings, the percentage of order corresponding to each region is calculated for the logistic map. In each region, the resultant area occupied by order, or the supplementary area occupied by chaos, participates in a sequence similar to Feigenbaum's one, which converges to the same respective Feigenbaum's constant.
Eye-Centered, Head-Centered, and Complex Coding of Visual and Auditory Targets in the Intraparietal Sulcus
Authors: Mullette-Gillman O'Dhaniel A. , Cohen Yale E. , Groh Jennifer M.
Published: April 2005

The integration of visual and auditory events is thought to require a joint representation of visual and auditory space in a common reference frame. We investigated the coding of visual and auditory space in the lateral and medial intraparietal areas (LIP, MIP) as a candidate for such a representation. We recorded the activity of 275 neurons in LIP and MIP of two monkeys while they performed saccades to a row of visual and auditory targets from three different eye positions. We found 45% of these neurons to be modulated by the locations of visual targets, 19% by auditory targets, and 9% by both visual and auditory targets. The reference frame for both visual and auditory receptive fields ranged along a continuum between eye- and head-centered reference frames with ∼10% of auditory and 33% of visual neurons having receptive fields that were more consistent with an eye- than a head-centered frame of reference and 23 and 18% having receptive fields that were more consistent with a head- than an eye-centered frame of reference, leaving a large fraction of both visual and auditory response patterns inconsistent with both head- and eye-centered reference frames. The results were similar to the reference frame we have previously found for auditory stimuli in the inferior colliculus and core auditory cortex. The correspondence between the visual and auditory receptive fields of individual neurons was weak. Nevertheless, the visual and auditory responses were sufficiently well correlated that a simple one-layer network constructed to calculate target location from the activity of the neurons in our sample performed successfully for auditory targets even though the weights were fit based only on the visual responses. We interpret these results as suggesting that although the representations of space in areas LIP and MIP are not easily described within the conventional conceptual framework of reference frames, they nevertheless process visual and auditory spatial information in a similar fashion.
Finger and Face Representations in the Ipsilateral Precentral Motor Areas in Humans
Authors: Hanakawa Takashi , Parikh Sachin , Bruno Michiko K. , Hallett Mark
Published: April 2005

Several human neuroimaging studies have reported activity in the precentral gyrus (PcG) ipsilateral to the side of hand movements. This activity has been interpreted as the part of the primary motor cortex (M1) that controls bilateral or ipsilateral hand movements. To better understand hand ipsilateral-PcG activity, we performed a functional MRI experiment in eight healthy right-handed adults. Behavioral tasks involved hand or lower face movements on each side or motor imagery of the same movements. Consistent with the known M1 organization, the hand contralateral-PcG activity was centered at the “hand-knob” portion of the PcG; face contralateral-PcG activity was localized ventrolateral to it. Hand ipsilateral-PcG activity was identified in most subjects. However, converging results indicated that this ipsilateral PcG activity was situated in Brodmann's area 6 in both hemispheres. The hand ipsilateral-PcG zones were active not only during hand movements but also face movements. Moreover, the hand ipsilateral-PcG zones revealed substantial imagery-related activity, which also failed to differentiate the hand and face. Statistical analyses confirmed poor effector selectivity of the hand ipsilateral PcG activity during both movement and imagery tasks. From these results, we conclude that the hand ipsilateral-PcG activity in healthy adults probably corresponds to a part of the ventral premotor cortex. In contrast, available evidence suggests that M1 contributes to controlling the ipsilateral hand in children and patients after stroke recovery. It appears that within the human PcG, there are two parallel systems potentially capable of controlling ipsilateral hand movements: ventral premotor cortex and M1. These two systems may be differentially influenced by developmental or pathologic changes.
Striatal Potassium Channel Dysfunction in Huntington's Disease Transgenic Mice
Authors: Ariano Marjorie A. , Cepeda Carlos , Calvert Christopher R. , Flores-Hernández Jorge , Hernández-Echeagaray Elizabeth , Klapstein Gloria J. , Chandler Scott H. , Aronin Neil , DiFiglia Marian , Levine Michael S.
Published: April 2005

Huntington's disease (HD) is a neurodegenerative disorder that mainly affects the projection neurons of the striatum and cerebral cortex. Genetic mouse models of HD have shown that neurons susceptible to the mutation exhibit morphological and electrophysiological dysfunctions before and during development of the behavioral phenotype. We used HD transgenic mouse models to examine inwardly and outwardly rectifying K+ conductances, as well as expression of some related K+ channel subunits. Experiments were conducted in slices and dissociated cells from two mouse models, the R6/2 and TgCAG100, at the beginning and after full development of overt behavioral phenotypes. Striatal medium-sized spiny neurons (MSNs) from symptomatic transgenic mice had increased input resistances, depolarized resting membrane potentials, and reductions in both inwardly and outwardly rectifying K+ currents. These changes were more dramatic in the R6/2 model than in the TgCAG100. Parallel immunofluorescence studies detected decreases in the expression of K+ channel subunit proteins, Kir2.1, Kir2.3, and Kv2.1 in MSNs, which contribute to the formation of the channel ionophores for these currents. Attenuation in K+ conductances and channel subunit expression contribute to altered electrophysiological properties of MSNs and may partially account for selective cellular vulnerability in the striatum.
Intact Ability to Learn Internal Models of Arm Dynamics in Huntington's Disease But Not Cerebellar Degeneration
Authors: Smith Maurice A. , Shadmehr Reza
Published: April 2005

Two different compensatory mechanisms are engaged when the nervous system senses errors during a reaching movement. First, on-line feedback control mechanisms produce in-flight corrections to reduce errors in the on-going movement. Second, these errors modify the internal model with which the motor plan is transformed into motor commands for the subsequent movements. What are the neural mechanisms of these compensatory systems? In a previous study, we reported that while on-line error correction was disturbed in patients with Huntington's disease (HD), it was largely intact in patients with cerebellar degeneration. Here we altered dynamics of reaching and studied the effect of error in one trial on the motor commands that initiated the subsequent trial. We observed that in patients with cerebellar degeneration, motor commands changed from trial-to-trial by an amount that was comparable to control subjects. However, these changes were random and were uninformed by the error in the preceding trial. In contrast, the change in motor commands of HD patients was strongly related to the error in the preceding trial. This error-dependent change had a sensitivity that was comparable to healthy controls. As a result, HD patients exhibited no significant deficits in adapting to novel arm dynamics, whereas cerebellar subjects were profoundly impaired. These results demonstrate a double dissociation between on-line and trial-to-trial error correction suggesting that these compensatory mechanisms have distinct neural bases that can be differentially affected by disease.
Interlimb Influences on Paretic Leg Function in Poststroke Hemiparesis
Authors: Kautz S. A. , Patten C.
Published: April 2005

After stroke, paretic leg motor impairment is typically viewed as a unilateral control deficit. However, much of the neural circuitry controlling normal leg function is organized bilaterally to produce coordinated, task-specific activity in the two legs. Thus, as a result of contralesional neural control processes, paretic leg motor pattern generation may be substantially influenced by the nonparetic leg sensorimotor state during bilateral lower limb tasks. Accordingly, we investigated whether different paretic leg motor patterns are observed during mechanically equivalent bilateral and unilateral tasks and, if so, whether nonparetic leg participation improved or exacerbated paretic leg coordination deficits. A pedaling apparatus that mechanically decoupled the legs was used to present subjects with increasingly complex bi- and unilateral motor tasks: isometric force generation, discrete movement, and pedaling. Bilateral electromyographic and pedal force data were collected from 21 persons with chronic poststroke hemiparesis and 11 similarly aged controls. During isometric force generation and discrete movements, nonparetic leg influences on paretic leg coordination were similar and not markedly different from interlimb influences in controls. In bilateral pedaling, however, interlimb influences differed from controls such that paretic leg coordination deficits were exacerbated. During pedaling movements, the suppression of interlimb influences similar to those observed in isometric and discrete movement may occur in controls but may be disrupted in hemiparesis. We suggest that the coupling of pattern generation between the two legs may result in greater, albeit more impaired, paretic leg motor output during bilateral pedaling than during unilateral pedaling.
Inhibition of Afferent Transmission in the Feeding Circuitry of Aplysia: Persistence Can Be as Important as Size
Authors: Evans Colin G. , Romero Adarli , Cropper Elizabeth C.
Published: April 2005

We are studying afferent transmission from a mechanoafferent, B21, to a follower, B8. During motor programs, afferent transmission is regulated so that it does not always occur. Afferent transmission is eliminated when spike propagation in B21 fails, i.e., when spike initiation is inhibited in one output region-B21's lateral process. Spike initiation in the lateral process is inhibited by the B52 and B4/5 cells. Individual B52 and B4/5-induced inhibitory postsynaptic potentials (IPSPs) in B21 differ. For example, the peak amplitude of a B4/5-induced IPSP is four times the amplitude of a B52 IPSP. Nevertheless, when interneurons fire in bursts at physiological (i.e., low) frequencies, afferent transmission is most effectively reduced by B52. Although individual B52-induced IPSPs are small, they have a long time constant and summate at low firing frequencies. Once IPSPs summate, they effectively block afferent transmission. In contrast, individual B4/5-induced IPSPs have a relatively short time constant and do not summate at low frequencies. B52 and B4/5 therefore differ in that once synaptic input from B52 becomes effective, afferent transmission is continuously inhibited. In contrast, periods of B4/5-induced inhibition are interspersed with relatively long intervals in which inhibition does not occur. Consequently, the probability that afferent transmission will be inhibited is low. In conclusion, it is widely recognized that afferent transmission can be regulated by synaptic input. Our experiments are, however, unusual in that they relate specific characteristics of postsynaptic potentials to functional inhibition. In particular we demonstrate the potential importance of the IPSP time constant.
Should we still be testing for asymptomatic non-specific urethritis in departments of genitourinary medicine?
Authors: Horner P J
Published: April 2005

It has recently been advocated that non-invasive testing with first-catch urine specimens using nucleic acid amplification techniques, to detect Chlamydia trachomatis and Neisseria gonorrhoeae, should replace routine microscopy on asymptomatic men. Although it is assumed that this strategy will be cost effective, the available evidence suggests that this will result in fewer sexually transmitted infections being averted than continuing the current practice of screening for urethritis and testing for both microorganisms in asymptomatic men. This review article summarizes the available evidence and argues that research is urgently needed in order to properly evaluate the cost-effectiveness of detecting urethritis in asymptomatic men.
Introduction of a proforma in the management of under age attendees at a genitourinary clinic
Authors: Holkar S , Rogstad K E
Published: April 2005

The aim of this review was evaluation of a recently developed proforma for improving assessment and management of patients under the age of 16 in the genitourinary (GU) medicine clinic. A case-note review of all under-16s attending between June 2000 and March 2001 was undertaken (109 patients). Comparison with review from 1998 prior to proforma introduction was carried out. In all, 99 proformas were completed. Fewer young patients were seen solely by junior doctors since proforma introduction (27–45%) ( P=0.012), more were referred to health advisors (79% versus 66%) ( P=0.056), but follow-up remains suboptimal (72% versus 78%). Possibility of abuse was assessed in 102 patients (17 cases of nonconsensual sex versus six in 1998). In all, 54% were using no contraception and only 21% were consistently using barrier methods; 41% had sexually transmitted infections diagnosed. The proforma is useful for collecting data and directing management when completed fully, and has revealed greater numbers of children involved in risky behaviour and abuse.
Soft Systems Methodology: A Context Within a 50-Year Retrospective of OR/MS
Authors: Reisman Arnold , Oral Muhittin
Published: April 2005

Soft systems methodology (SSM) has been used in the practice of operations research and management science (OR/MS) since the early 1970s. In the 1990s, it emerged as a viable academic discipline. Unfortunately, its proponents consider SSM and traditional systems thinking to be mutually exclusive. Despite the differences claimed by SSM proponents between the two, they have been complementary. An extensive sampling of the OR/MS literature over its entire lifetime demonstrates the richness with which the non-SSM literature has been addressing the very same issues as does SSM.
People Skills: Change Management Tools—Leading Teams
Authors: Levasseur Robert E.
Published: April 2005

This is the fourth in a series of columns about some of the most effective models, methods, and processes of organization development (OD), a discipline that offers much to the OR/MS practitioner determined to help clients solve real-world problems. Because it is based on a systemic view of organizations, OD includes the whole universe of fuzzy people issues that increasingly determine the success or failure of efforts to implement otherwise flawless technical solutions.
The Fifth Column: On Using Operations Research to Fund Operations Research (Economically)
Authors: Woolsey Gene
Published: April 2005

University administrators may have futures in politics.
Large Sample Properties of Weighted Monte Carlo Estimators
Authors: Glasserman Paul , Yu Bin
Published: April 2005

A general approach to improving simulation accuracy uses information about auxiliary control variables with known expected values to improve the estimation of unknown quantities. We analyze weighted Monte Carlo estimators that implement this idea by applying weights to independent replications. The weights are chosen to constrain the weighted averages of the control variables. We distinguish two cases (unbiased and biased), depending on whether the weighted averages of the controls are constrained to equal their expected values or some other values. In both cases, the number of constraints is usually smaller than the number of replications, so there may be many feasible weights. We select maximally uniform weights by minimizing a separable convex function of the weights subject to the control variable constraints. Estimators of this form arise (sometimes implicitly) in several settings, including at least two in finance: calibrating a model to market data (as in the work of Avellaneda et al. 2001) and calculating conditional expectations to price American options. We analyze properties of these estimators as the number of replications increases. We show that in the unbiased case, weighted Monte Carlo reduces asymptotic variance, and that all convex objective functions within a large class produce estimators that are very close to each other in a strong sense. In contrast, in the biased case the choice of objective function does matter. We show explicitly how the choice of objective determines the limit to which the estimator converges.
Dynamic Pricing and Learning in Electricity Markets
Authors: Garcia Alfredo , Campos-Nañez Enrique , Reitzes James
Published: April 2005

We analyze the price-formation process in an infinite-horizon oligopoly model where hydroelectric generators engage in dynamic price-based competition. The analysis focuses on the role of “indifference” prices, i.e., prices that equate the gains from releasing or storing water. Strategies where players bid their indifference prices and the marginal player undercuts the lowest-cost unsuccessful bidder constitute a Markov Perfect Equilibrium (MPE) under appropriate conditions. These conditions involve symmetric production capacity and nonfractional (i.e., “all or nothing”) output by successful bidders. Although the MPE solution represents an equilibrium consistent with dynamic strategic behavior, it requires computational sophistication by market participants. However, a basic “learning” procedure involving indifference prices converges to an MPE.
An Efficient Optimal Solution to the Two-Hoist No-Wait Cyclic Scheduling Problem
Authors: Liu Jiyin , Jiang Yun
Published: April 2005

Hoist scheduling is a typical problem in the operation of electroplating systems. The cyclic scheduling policy is widely used in these systems in industry. Research on hoist scheduling has focused on the cyclic problem to minimize the cycle length. Most previous studies consider the single-hoist case. In practice, however, more than one hoist is often used in an electroplating line. This paper addresses the two-hoist, no-wait cyclic scheduling problem, in which the tank-processing times are constants and, upon completion of processing in a tank, the parts have to be moved to the next tank immediately. Based on the analysis of the problem properties, a polynomial algorithm is developed to obtain an optimal schedule. This algorithm first identifies a set of thresholds, which are special values of the cycle length, so that the feasibility property may change only at these thresholds. Feasibility checking is then carried out on each individual threshold in ascending order. The first feasible threshold found will be the optimal cycle length, and the corresponding feasible schedule is an optimal hoist schedule.
Solving a Time-Space Network Formulation for the Convoy Movement Problem
Authors: Chardaire P. , McKeown G. P. , Verity-Harrison S. A. , Richardson S. B.
Published: April 2005

We give a formal specification for a strategic network routing problem known as the convoy movement problem (CMP) and establish that the corresponding feasibility problem is NP-complete. We then introduce an integer programming (IP) model based on the concept of a time-space network and apply a Lagrangian relaxation to this model. We discuss how the dual function may be evaluated using a modified version of Dijkstra’s algorithm suitable to very large, implicitly defined graphs and show how heuristic solutions to the primal problem may be obtained. We present results for a number of instances of the CMP, most of which are based on real-world problems. The number of convoys in these instances varies between 15–25, and their movement time requires up to several thousand time units in networks ranging in size from a few dozen to several thousand vertices and edges. The most difficult instance tested involves 17 long convoys each taking four times the average link travel time to pass through a point in the network. This instance is solved within 3.3% of optimality in less than 3.5 hours of computing time on a Dell Precision 420 dual processor computer. Every other test instance is solved within 2% of the optimal value in less than 20 minutes of computing time.
The Use of Ozone in Dentistry and Medicine
Authors: Baysan Aylin , Lynch Edward
Published: April 2005

There is growing interest in the use of ozone in oral healthcare and the National Institute for Clinical Excellence (NICE) is at present reviewing the evidence for its effectiveness in the management of occlusal and plain surface caries. These are only two of the clinical problems for which ozone can, and has, been used; it has also been employed for a wide variety of other purposes in both dentistry and medicine. This pale blue-coloured gas plays an important role as a natural constituent in the higher layer of the Earth's atmosphere. There is growing evidence that it can be employed as a useful therapeutic agent. This paper reviews its therapeutic uses to date and suggests its possible future clinical applications. Consumer demands for this strong oxidant may increase as the general public becomes increasingly aware of its therapeutic capacity and the non-invasive manner in which it can be administered.
Patient-Active Prevention in Primary Dental Care: A Characterisation of General Practices in Northern Ireland
Authors: Freeman Ruth , Kerr Gail , Salmon Kathy , Speedy Patti
Published: April 2005

Aim

To investigate the preventive orientation of general dental practices by examining their patient-active prevention activities, practice policies for prevention and employment strategies.

Method

All general dental practices located within the region of the Eastern Health and Social Services Board (EHSSB) in Northern Ireland were contacted and invited to participate. A questionnaire assessed practice characteristics, patient-active prevention, practice policies and employment strategies. The principal general dental practitioner (GDP) was invited to complete the questionnaire.

Results

Seventy-seven per cent of practices participated. Nearly all the practices provided patient-active prevention; however, lower proportions of dentists provided advice on diet for dental caries (3%), oral hygiene instruction, fluoride toothpaste use and interdental cleaning (7%) with each new course of dental treatment. ‘Patient-active’ prevention practices were 5.8 times more likely to employ a hygienist and 5.3 times more likely to have a practice policy to screen for oral cancer.

Conclusions

These findings suggest that the employment of a hygienist is central to the reorientation of primary dental care. The Government must be encouraged to provide the financial means to allow primary care to shift from being disease-centred to health-focused.
Role of oestrogen in the regulation of bone turnover at the menarche
Authors: Eastell Richard
Published: April 2005

The rise in oestrogen levels at menarche in girls is associated with a large reduction in bone turnover markers. This reduction reflects the closure of the epiphyseal growth plates, the reduction in periosteal apposition and endosteal resorption within cortical bone, and in bone remodelling within cortical and cancellous bone. Oestrogen promotes these changes, in part, by promoting apoptosis of chondrocytes in the growth plate and osteoclasts within cortical and cancellous bone. The period of early puberty is associated with an increased risk of fracture, particularly of the distal forearm, and this may be related to the high rate of bone turnover. A late menarche is a consistent risk factor for fracture and low bone mineral density in the postmenopausal period; models that might explain this association are considered.
NF-κB Mediated IL-6 Production by Renal Epithelial Cells Is Regulated by C-Jun NH2-Terminal Kinase
Authors: de Haij Simone , Bakker Astrid C. , van der Geest Reinier N. , Haegeman Guy , Vanden Berghe Wim , Aarbiou Jamil , Daha Mohamed R. , van Kooten Cees
Published: April 2005

Tubular epithelial cells (TEC) play an important role in tubulointerstitial inflammation, a hallmark of most renal diseases, via production of cytokines and chemokines. In this study, the role of mitogen-activated protein kinases (MAPK) in regulation of the proinflammatory cytokine IL-6 in cultured human TEC in response to the leukocyte-derived factors IL-1, TNF-α, IL-17, and CD40L was investigated. IL-6 production induced by IL-1, TNF-α, and IL-17 was specifically inhibited by the c-jun NH2-terminal kinase (JNK) inhibitor SP600125, but not by a selective inhibitor of p38 MAPK, and was moderately increased when the ERK1/2 pathway was inhibited. Also for CD40L stimulation, inhibition of JNK resulted in a pronounced inhibition of IL-6 production. Although stimulation of TEC induced activation of activator protein-1 (AP-1), the down-stream target of JNK, reporter assays demonstrated that mutation of the AP-1 binding site in the IL-6 promoter did not affect gene transcription. Furthermore, IL-1-induced transcriptional activation of the IL-6 promotor was repressed by SP600125 or by co-transfection of a dominant-negative expression plasmid of c-jun even in the absence of a functional AP-1 binding site. This suggests that IL-6 production by renal epithelial cells is regulated by JNK, via a mechanism, however, independent of the AP-1 binding site. The data rather suggest that the JNK pathway may interfere with other signaling pathways, involving NF-κB and possibly ERK.
Polarisation-sensitive optical coherence tomography for material characterisation and testing
Authors: Stifter D , Dufau A D Sanchis , Breuer E , Wiesauer K , Burgholzer P , Höglinger O , Götzinger E , Pircher M , Hitzenberger C K
Published: April 2005

Optical Coherence Tomography (OCT) is an emerging technology for high-resolution non-contact imaging of semi-transparent structures. Originally developed for medical diagnostics, we extend the OCT-technique to problems posed in material testing and characterisation. Layer thickness
and refractive indices as well as internal structures of polymer parts have been determined within this study. An extension of OCT, namely polarisation-sensitive OCT (PS-OCT) has been used to identify regions of increased anisotropy within injection-moulded plastic parts and to determine quantitatively
internal strain within translucent materials in a non-destructive way.
Effects of Activated Platelet Concentrates on Human Primary Cultures of Fibroblasts and Osteoblasts
Authors: Cenni E. , Ciapetti G. , Pagani S. , Perut F. , Giunti A. , Baldini N.
Published: April 2005

Background: Platelet alpha granules contain growth factors released into the surrounding environment during activation. This property has been used in clinical medicine to accelerate the repair process by activating in vitro autologous platelets with thrombin and has also been proposed to promote the proliferation of bone cells. The aim of this research was to assess the effect of platelet concentrates activated with thrombin on human gingival fibroblasts and human osteoblasts from trabecular bone.

Methods: Platelet concentrates, activated with bovine thrombin, were added to the cells in serum‐free medium. The cultures were assessed for proliferation by vital stain and cell count after 72‐hour incubation. Alkaline phosphatase activity was tested after 72‐hour incubation on the osteoblast lysates by a colorimetric assay. After 21 days the formation of mineral nodules was tested in the osteoblast cultures by alizarin red staining. The effects of the activated platelet concentrates (APC) were compared with the serum‐free medium (SF), or with platelet‐poor plasma added medium (PPP).

Results: The fibroblast growth in the presence of APC was higher, though not significantly, than SF. APC resulted in a nonsignificant decrease in proliferation and alkaline phosphatase expression in osteoblasts, compared both to serum free medium, and PPP. Mineralization was only modestly increased after incubation with APC in comparison with serum‐free medium.

Conclusions: There were no statistical differences in fibroblast proliferation, or in osteoblast growth and functions between serum‐free conditions and the platelet gel treatment. Therefore, neither fibroblast proliferation nor osteoblast growth and functions were affected by the activated platelet concentrates in vitro. J Periodontol 2005;76:323‐328.
Inhibitory Effects of Areca Nut Extracts on Phagocytosis of Actinobacillus actinomycetemcomitans ATCC 33384 by Neutrophils
Authors: Hung Shan‐Ling , Cheng Yi‐Yun , Peng Ji‐Lung , Chang Lien‐Yu , Liu Tsung‐Yun , Chen Yen‐Ting
Published: April 2005

Background: Areca quid chewers have a higher prevalence of periodontal disease than non‐chewers. Little is known about the influence of areca quid on the immune system. This study was to determine the possible effects of the areca nut on phagocytic activity of human neutrophils.

Methods: Aqueous extracts of ripe areca nut without husk (rANE), fresh and tender areca nut with husk (tANE), a major alkaloid (arecoline), and a phenolic component ([+]‐catechin) of areca nut were examined for their effects on cellular viability using trypan blue exclusion assay. The possible effects on the phagocytic activity of neutrophils against a periodontal pathogen, Actinobacillus actinomycetemcomitans ATCC 33384, were determined using flow cytometry and confocal laser scanning microscopy.

Results: At the concentrations tested, rANE, tANE, arecoline, and (+)‐catechin did not significantly affect viability of neutrophils. However, rANE, tANE, arecoline, and (+)‐catechin inhibited the phagocytic activity of neutrophils in a dose‐dependent manner. Approximately 50% of the relative phagocytic activity of neutrophils was affected when 50 µg/ml of rANE, 400 µg/ml of tANE, 20,000 µg/ml of arecoline, or 2,500 µg/ml of (+)‐ catechin was used. Decreased levels of internalized fluorescent bacteria were also demonstrated. However, arecoline or (+)‐catechin alone could not be used to explain the inhibitory effects observed for rANE and tANE.

Conclusions: Components of areca nut reduced the uptake of A. actinomycetemcomitans ATCC 33384 by human neutrophils. The inhibition of areca nut on phagocytosis of neutrophils may be one possible mechanism by which the areca nut compromises the periodontal health of areca quid chewers. J Periodontol 2005;76:373‐379.
Depletion of Polyamines and Increase of Transforming Growth Factor‐β1, c‐myc, Collagen‐Type I, Matrix Metalloproteinase‐1, and Metalloproteinase‐2 mRNA in Primary Human Gingival Fibroblasts
Authors: Stabellini Giordano , Moscheni Claudia , Gagliano Nicoletta , Dellavia Claudia , Calastrini Carla , Ferioli Maria Elena , Gioia Magda
Published: April 2005

Background: The polyamines spermidine, spermine, and putrescine are known to be deeply linked with growth processes, gene expression, and extracellular matrix synthesis. Their cellular content depends primarily on the activity of the enzyme ornithine decarboxylase. High levels of ornithine decarboxylase and polyamines have been found in proliferative, inflammatory, and neoplastic pathologies of the oral cavity and in gingival fluid. Difluoromethylornithine (DFMO) selectively inhibits ornithine decarboxylase, thus depleting polyamine content and preventing cell proliferation and synthesis activity. The aim of this study was to investigate whether DFMO treatment could modify the genes involved in cell proliferation and extracellular matrix turnover.

Methods: Fibroblasts derived from non‐inflamed gingiva were maintained in Dulbecco's modified Eagle's medium (DMEM) plus α‐difluoromethylornithine for 4 days. At 0, 24, 48, 72, and 96 hours cell number was assessed, polyamine levels were quantified with high performance liquid chromatography (HPLC) method, and transforming growth factor‐β1 (TGF‐β1), c‐myc, matrix metalloproteinases (MMP)‐1 and 2, collagen type I (COL‐I) and tissue inhibitor of matrix metalloproteinases (TIMP)‐1 were evaluated by reverse transcriptionpolymerase chain reaction (RT‐PCR).

Results: Fibroblasts treated with DFMO significantly decreased cell proliferation, ornithine decarboxylase activity, and putrescine levels at all treatment times, spermidine after 72 and 96 hours, and spermine after 96 hours of culture. Total polyamines decreased (P ≤0.01) at 96 hours after DFMO treatment, while c‐myc, TGF‐β1, MMP‐1 and 2, COL‐I mRNA significantly increased. Conversely, TIMP‐1 did not show any significant change. The polyamines trend was not correlated to c‐myc, TGF‐β1, MMP‐1 and ‐2, and TIMP‐1 mRNA levels. Transforming growth factor‐β1 and c‐myc mRNA expression were related and correlated to MMP‐1 and 2, COL‐I and TIMP‐1 mRNA trend after DFMO treatment.

Conclusions: Our data show that as the polyamine content decreases, TGF‐β1, c‐myc, MMP‐1 and ‐2, and COL‐I mRNA levels increase, therefore a negative regulatory role of the polyamines on the mRNA expression could be suggested. J Periodontol 2005;76:443‐449.
Synthesis, Microstructure and Mechanical Properties of Al40W60 Bulk Alloy Obtained by Mechanical Alloying and Hot‐Pressing
Authors: Zhu C.  J. , Ma X. F. , Zhao W. , Tang H. G. , Yan J. M. , Cai S. G.
Published: April 2005

The Al40W60 bulk alloy was fabricated by using mechanical alloying and hot‐pressing in this work. The Al40W60 solid solution had excellent thermal stability under vacuum. The optimum mechanical properties of Al40W60 alloy bulk samples were obtained when hot‐pressed. The microhardness, bending and compressive strength were 7.78GPa, 550MPa and 2.04GPa, respectively.
Synthesis of Cobalt/Polymer Multilayer Nanotubes
Authors: Nielsch K. , Castaño F. J. , Matthias S. , Lee W. , Ross C. A.
Published: April 2005

Cobalt/polymer multilayer nanotubes (see Figure) are formed by wetting of alumina and silicon membranes by polystyrene containing a metallo–organic precursor, followed by a thermal decomposition process. This article describes the fabrication and magnetic properties of high quality, thin‐walled ferromagnetic nanotubes. They might be very attractive for a broad range of potential applications ranging from biotechnology to magnetic storage devices.
Improvement of Corrosion‐Wear Resistance of Ti‐6Al‐4V Alloy by Plasma Mo‐N Surface Modification
Authors: Tang B. , Wu P.‐Q. , Fan A.‐L. , Qin L. , Hu H.‐J. , Celis J.‐P.
Published: April 2005

Ti‐6Al‐4V alloy has attracted increasing applications as a metallic biomaterial in recent years thanks to its good corrosion resistance and biocompatibility. However, the poor corrosion‐wear resistance of the alloy is thus a major concern to potential users. In this paper, the electrochemical noise technique is used as an on‐line tool to investigate the corrosion‐wear behavior of untreated and Mo‐N modified Ti‐6Al‐4V alloy sliding against corundum in Hanks' and sodium phosphate solutions.
Development of Formable All‐Metal Sandwich Sheets for Automotive Applications
Authors: Mohr D. , Straza G.
Published: April 2005

This paper describes the development of thin all‐metal sandwich sheets. Sandwich sheets are used in various engineering applications, but the lack of formability and weldability has prevented their wide spread use in the automotive industry. The failure modes of state‐of‐the‐art sandwich sheets in forming operations have been analyzed in detail. Based on theoretical analysis, a formable prototype sandwich sheets has been designed. A draw bending experiment has been performed to demonstrate the formability of this prototype sheet.
Titelbild: Calix[4]pyrrole: An Old yet New Ion‐Pair Receptor (Angew. Chem. 17/2005)
Authors: Custelcean Radu , Delmau Lætitia H. , Moyer Bruce A. , Sessler Jonathan L. , Cho Won‐Seob , Gross Dustin , Bates Gareth W. , Brooks Simon J. , Light Mark E. , Gale Philip A.
Published: April 2005

Ionenpaarkomplexierungseigenschaften mit möglichen Anwendungen in der Salzextraktion und im Kristall‐Engineering könnten ein neues Kapitel in der Chemie von Calix[4]pyrrolen aufschlagen. B. Moyer, J. Sessler, P. Gale et al. untersuchen in ihrer Zuschrift auf S. 2593 ff. die Bindungseigenschaften dieses Makrocyclus, der erstmals vor fast 120 Jahren synthetisiert wurde und noch immer für Überraschungen gut ist. Das Titelbild zeigt mehrere Darstellungen der an große Kationen, wie Caesium‐ und Imidazolium‐Ionen, und unterschiedliche Halogenid‐ und Oxo‐Anionen gebundenen Calix[4]pyrrol‐Einheit.
On efficiently solving a class of atmospheric radiative transfer problems using discrete ordinates models for bidirectional functions: the uppermost layer
Authors: de Abreu Marcos Pimenta
Published: April 2005

We derive discrete models for bidirectional functions defined for the uppermost layer of a multislab model atmosphere. These models can be used to solve efficiently a set of multislab transfer problems characterized by an optically stationary uppermost layer. We illustrate with numerical results for a representative set of multislab problems. Copyright © 2005 Royal Meteorological Society
Synthesis, Structural Features, Absorption Spectra, Redox Behaviour and Luminescence Properties of Ruthenium(II) Rack‐Type Dinuclear Complexes with Ditopic, Hydrazone‐Based Ligands
Authors: Stadler Adrian‐Mihail , Puntoriero Fausto , Campagna Sebastiano , Kyritsakas Nathalie , Welter Richard , Lehn Jean‐Marie
Published: April 2005

The isomeric bis(tridentate) hydrazone ligand strands 1 a–c react with [Ru(terpy)Cl3] (terpy=2,2′:6′,2′′‐terpyridine) to give dinuclear rack‐type compounds 2 a–c, which were characterised by several techniques, including X‐ray crystallography and NMR methods. The absorption spectra, redox behaviour and luminescence properties (both in fluid solution at room temperature and in rigid matrix at 77 K) of the ligand strands 1 a–c and of the metal complexes 2 a–c have been studied. Compounds 1 a–c exhibit absorption spectra dominated by intense π–π* bands, which, in the case of 1 b and 1 c, extend within the visible region, while the absorption spectra of the rack‐type complexes 2 a–c show intense bands both the in the UV region, due to spin‐allowed ligand‐centred (LC) transitions, and in the visible, due to spin‐allowed metal‐to‐ligand charge‐transfer (MLCT) transitions. The energy position of these bands strongly depends on the ligand strand: in the case of 2 a, the lowest energy MLCT band is around 470 nm, while in 2 b and 2 c, it lies beyond 600 nm. Ligands 1 a–c undergo oxidation processes that involve orbitals based mainly on the CH3NN fragments. The complexes 2 a–c undergo reversible metal‐centred oxidation, while reductions involve the hydrazone‐based ligands: in 2 b and 2 c, the bridging ligand is reduced twice and in 2 a once before reduction of the peripheral terpy ligands takes place. Ligands 1 a–c exhibit luminescence from the lowest‐lying 1π–π* level. Only for complex 2 a does emission occur; this may be attributed to a 3MLCT state involving the bridging ligand. Taken together, the results clearly indicate that the structural variations introduced translate into interesting differences in the spectroscopic, luminescence and redox properties of the ligand strands as well as of the rack‐type metal complexes.
EPR, ENDOR, and DFT Studies on (β‐Octahalo‐meso‐tetraarylporphyrin)copper Complexes: Characterization of the Metal(d)−Porphyrin(a2u) Orbital Interaction
Authors: Shao Junlong , Steene Erik , Hoffman Brian M. , Ghosh Abhik
Published: April 2005

A series of planar (porphyrin)copper(II) complexes and their β‐octahalogenated saddled derivatives have been studied by Electron Paramagnetic Resonance (EPR) spectroscopy, Electron Nuclear DOuble Resonance (ENDOR) spectroscopy, and Density Functional Theoretical (DFT) calculations. Both EPR/ENDOR spectroscopy and DFT calculations indicate a decrease in spin density on the central copper(II) ion and on the nitrogen atoms in the saddled compounds relative to the planar complexes. The EPR/ENDOR measurements show that the hyperfine coupling decreases by 12% on the nitrogen atoms and 9% on the copper ion, in going from planar (5,10,15,20‐tetraphenylporphyrin)copper (Cu[TPP]) to saddled (2,3,7,8,12,13,17,18‐octabromo‐5,10,15,20‐tetraphenylporphyrin)copper (Cu[Br8TPP]). Accordingly, saddling results in a decrease in the spin density on the copper ion and on the nitrogen atoms. DFT calculations on Cu[Br8TPP] yield spin populations of 42.4% on the copper ion, 9.9% on each nitrogen atom and 4.9% on each meso carbon atom, relative to DFT spin populations of 62, 10.2 and 0.3% on the copper ion, each nitrogen and each meso carbon atom, respectively, for porphinecopper (Cu[P]). These calculations further indicate that the decrease in spin density on the copper ion in the saddled complexes results from a saddling‐induced Cu(d)−porphyrin(a2u) orbital overlap whereby some of the Cu spin density is delocalized onto the porphyrin ring. The decrease in nitrogen spin population with saddling appears to be a more subtle effect caused by a superposition of two opposing factors. Saddling decreases the overlap between the nitrogen lone pairs and the Cu d orbital on one hand and enhances the overlap between the copper d orbital and the porphyrin a2u HOMO on the other. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
A Copper‐Metalated, Hybrid Inorganic–Organic Polymer as an Oxidative Nuclease
Authors: Chandrasekhar Vadapalli , Athimoolam Arunachalampillai , Krishnan Venkatasubbaiah , Azhakar Ramachandran , Madhavaiah C. , Verma Sandeep
Published: April 2005

This study describes nucleolytic activity of a copper‐metalated, multisite‐coordinating, hybrid polymer CPPL‐Cu under oxidative conditions. Rapid relaxation of supercoiled plasmid DNA was observed and mechanistic probing by chemical and enzymatic assays revealed involvement of singlet‐oxygen‐derived reactive species. The heterogeneous nature of the catalyst allowed a facile recycling of the artificial nuclease. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Synthesis, Structure, and Luminescent Properties of Guanidinate‐Based Terbium Complexes
Authors: Pang Xingan , Sun Hongmei , Zhang Yong , Shen Qi , Zhang Hongjie
Published: April 2005

Two guanidinate‐based terbium complexes [iPrNC(NiPr2)NiPr]mTbCl3–m [m = 3 (1), 2 (2)] were synthesized, and the crystal structure of 1 was determined by single‐crystal X‐ray diffraction. Complexes 1 and 2 were further characterized by elemental analysis, IR, and 1H NMR spectroscopy. In complex 1 the guanidinate ligand coordinates to the terbium atom through the nitrogen atoms in a bidentate chelating coordination mode. As a result of an efficient energy transfer from the guanidinate ligand to the central Tb3+, both 1 and 2 have been found to exhibit strong green emission corresponding to Tb3+ 5D4‐7FJ (J = 6, 5, 4, 3) transitions. Among them, the emission 5D4‐7F5 (550 nm) is the most prominent. The lifetimes of the 5D4 Tb3+ excited levels of the two complexes were determined to be around 0.90 ms. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Mixed f‐d Metallomesogens with an Extended Rigid Core
Authors: Binnemans Koen , Lodewyckx Katleen , Donnio Bertrand , Guillon Daniel
Published: April 2005

The liquid‐crystalline behaviour of copper(II) and nickel(II) complexes of a mesogenic Schiff‐base ligand derived from N,N'‐disalicylidene‐1,2‐phenylenediamine (salophenH2) and of the corresponding trinuclear mixed copper(II)/lanthanum(III) and nickel(II)/lanthanum(III) complexes was investigated. High‐temperature X‐ray diffraction studies revealed that both the parent transition metal complexes and the mixed f‐d complexes exhibit a hexagonal columnar phase (Colh) over an extended temperature range. Complex formation with lanthanum(III) nitrate resulted in an increase of the transition temperatures. The geometrical parameters (lattice parameters and column cross‐section) of all the metal complexes are very similar, which indicates that the local organisation in the mesophase is the same despite their structural differences. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)