Incorporating Ecosystem Services into Water Resources Management-Tools, Policies, Promising Pathways

Ecosystems provide a range of services, including water purification, erosion prevention, and flood risk mitigation, that are important to water resource managers. But as a sector, water resources management has been slow to incorporate ecosystem protection and restoration, for a variety of reasons, although related concepts such as nature-based solutions and green infrastructure are gaining traction. We explain some of the existing challenges to wider uptake of the ecosystem services concept in water resources management and introduce some promising avenues for research and practice, elaborated in more detail through 12 papers, spanning five continents and a variety of contexts, which make up a Special Issue on "Incorporating Ecosystem Services into Water Resources Management". Cross-cutting themes include (A) ecosystem services as a flexible concept to communicate with stakeholders; (B) participatory processes to involve stakeholders in research; (C) multiple values, and valuation methods, of water-related services; and (D) applications of decision-support tools. We conclude with a summary of research gaps and emphasize the importance of co-producing knowledge with decision makers and other stakeholders, in order to improve water resources management through the integration of ecosystem services.

Operationalizing Integrated Water Resource Management in Latin America: Insights from Application of the Freshwater Health Index

Water crises in Latin America are more a consequence of poor management than resource scarcity. Addressing water management issues through better coordination, identification of problems and solutions, and agreement on common objectives to operationalize integrated water resources management (IWRM) could greatly improve water governance in the region. Composite indices have great potential to help overcome capacity and information challenges while supporting better IWRM. We applied one such index, the Freshwater Health Index (FHI) in three river basins in Latin America (Alto Mayo, Perú; Bogotá, Colombia; and Guandu, Brazil) to assess freshwater ecosystem vitality, ecosystem services, and the water governance system in place. The approach included convening management agencies, water utilities, planning authorities, local NGOs and industries, community groups and researchers to co-implement the FHI. The results provide detailed information on the ecological integrity of each basin and the sustainability of the ecosystem services being provided. All three basins show very low scores for governance and stakeholder engagement, thus improving both in the region should be a priority. The results also shed light on how the FHI framework can help inform decision-making to improve IWRM implementation by facilitating stakeholder engagement while contributing to coordination, identification of problems and solutions as well as agreement on common objectives. Because implementation of IWRM is part of the solution for the United Nations Sustainable Development Goal (SDG) 6.5 ("By 2030, implement IWRM at all levels, including through transboundary cooperation as appropriate"), our case studies can serve as examples to other Latin American countries to achieve SDG 6.5.

Integrating Ecosystem Services Into Water Resource Management: An Indicator-Based Approach

Natural ecosystems are fundamental to local water cycles and the water ecosystem services that humans enjoy, such as water provision, outdoor recreation, and flood protection. However, integrating ecosystem services into water resources management requires that they be acknowledged, quantified, and communicated to decision-makers. We present an indicator framework that incorporates the supply of, and demand for, water ecosystem services. This provides an initial diagnostic for water resource managers and a mechanism for evaluating tradeoffs through future scenarios. Building on a risk assessment framework, we present a three-tiered indicator for measuring where demand exceeds the supply of services, addressing the scope (spatial extent), frequency, and amplitude for which objectives (service delivery) are not met. The Ecosystem Service Indicator is measured on a 0-100 scale, which encompasses none to total service delivery. We demonstrate the framework and its applicability to a variety of services and data sources (e.g., monitoring stations, statistical yearbooks, modeled datasets) from case studies in China and Southeast Asia. We evaluate the sensitivity of the indicator scores to varying levels data and three methods of calculation using a simulated test dataset. Our indicator framework is conceptually simple, robust, and flexible enough to offer a starting point for decision-makers and to accommodate the evolution and expansion of tools, models and data sources used to measure and evaluate the value of water ecosystem services.

Diagnosing challenges and setting priorities for sustainable water resource management under climate change

Managing transboundary river basins requires balancing tradeoffs of sustainable water use and coping with climate uncertainty. We demonstrate an integrated approach to exploring these issues through the lens of a social-ecological system, combining remote and in-situ earth observations, hydrologic and climate models, and social surveys. Specifically, we examine how climate change and dam development could impact the Se Kong, Se San and Sre Pok rivers in the Mekong region. We find that climate change will lead to increased precipitation, necessitating a shift in dam operations, from maintaining low flows to reducing flood hazards. We also find that existing water governance systems in Laos, Vietnam, and Cambodia are ill-prepared to address the problem. We conclude that the solution space for addressing these complex issues will be highly constrained unless major deficiencies in transboundary water governance, strategic planning, financial capacity, information sharing, and law enforcement are remedied in the next decades.

A Phytocannabinoid Formula Containing Palmitoylethanolamide, Acmella Oleracea Extract, and Bovine Colostrum Filtrate Inhibited Cytokine and Chemokine Production in Human Peripheral Blood Mononuclear Cells Stimulated Ex Vivo

A phytocannabinoid formula containing copaiba essential oil, palmitoylethanolamide, Sichuan pepper extract, Acmella oleracea extract, cruciferous vegetable extracts blend, and bovine colostrum filtrate was tested for its ex vivo effect on inhibiting stimulated cytokine release in human peripheral blood mononuclear cells. Effects of the phytocannabinoid formula on the peripheral blood mononuclear cells viability were measured by alamarBlue™ to confirm no obvious cytotoxicity. The phytocannabinoid formula was compared to reference compounds for its ability to inhibit both the phytohemagglutinin-stimulated release of the cytokines from T-cells and the lipopolysaccharide-stimulated release of the cytokines from macrophages/monocytes in human peripheral blood mononuclear cells. The T cell cytokine responses measured were those of interleukins (interleukin-1β, interleukin-2, interleukin-4, interleukin-5, interleukin-6, interleukin-8, interleukin-10, and interleukin-13) and interferon-gamma, interferon gamma-induced protein 10, macrophage inflammatory protein-1α, and tumor necrosis factor-α. The macrophage and monocyte cytokine responses measured were of interleukin-1β, interleukin-6, interleukin-8, macrophage inflammatory protein-1α, and tumor necrosis factor-α. For the phytohemagglutinin-stimulated T cell production of cytokines, the peripheral blood mononuclear cells treated with the Phytocannabinoid formula at 2 μg/mL and 20 μg/mL showed significant inhibition of interleukin-2, interleukin-6, interleukin-5, interleukin-8, interleukin-10, interleukin-13, and interferon gamma-induced protein 10 production. The phytocannabinoid formula also significantly reduced the macrophage/monocyte production of interleukin-1β and interleukin-6. Results from the present study showed that the phytocannabinoid formula inhibited cytokines and chemokines production in ex vivo stimulated human peripheral blood mononuclear cells, suggesting a potential immunomodulatory effect.

Can we take the pulse of environmental governance the way we take the pulse of nature? Applying the Freshwater Health Index in Latin America

Quantitative assessments have long been used to evaluate the condition of the natural environment, providing information for standard setting, adaptive management, and monitoring. Similar approaches have been developed to measure environmental governance, however, the end result (e.g., numeric indicators) belies the subjective and normative judgments that are involved in evaluating governance. We demonstrate a framework that makes this information transparent, through an application of the Freshwater Health Index in three different river basins in Latin America. Water Governance is measured on a 0-100 scale, using data derived from perception-based surveys administered to stakeholders. Results suggest that water governance is a primary area of concern in all three places, with low overall scores (Guandu-26, Alto Mayo-38, Bogotá-43). We conclude that this approach to measuring governance at the river basin scale provides valuable information to support monitoring and decision making, and we offer suggestions on how it can be improved.

Integrating the social, hydrological and ecological dimensions of freshwater health: The Freshwater Health Index

Degradation of freshwater ecosystems and the services they provide is a primary cause of increasing water insecurity, raising the need for integrated solutions to freshwater management. While methods for characterizing the multi-faceted challenges of managing freshwater ecosystems abound, they tend to emphasize either social or ecological dimensions and fall short of being truly integrative. This paper suggests that management for sustainability of freshwater systems needs to consider the linkages between human water uses, freshwater ecosystems and governance. We present a conceptualization of freshwater resources as part of an integrated social-ecological system and propose a set of corresponding indicators to monitor freshwater ecosystem health and to highlight priorities for management. We demonstrate an application of this new framework -the Freshwater Health Index (FHI) - in the Dongjiang River Basin in southern China, where stakeholders are addressing multiple and conflicting freshwater demands. By combining empirical and modeled datasets with surveys to gauge stakeholders' preferences and elicit expert information about governance mechanisms, the FHI helps stakeholders understand the status of freshwater ecosystems in their basin, how ecosystems are being manipulated to enhance or decrease water-related services, and how well the existing water resource management regime is equipped to govern these dynamics over time. This framework helps to operationalize a truly integrated approach to water resource management by recognizing the interplay between governance, stakeholders, freshwater ecosystems and the services they provide.

Assessing the sustainability of freshwater systems: A critical review of composite indicators

Quantitative indicators are a common means of assessing the complex dimensions of a sustainable freshwater system, and framing scientific knowledge for policy and decision makers. There is an abundance of indicators in use, but considerable variation in terms of what is being measured and how indicators are applied, making it difficult for end-users to identify suitable assessment methods. We review 95 water-related indices and analyze them along their normative, procedural, and systemic dimensions to better understand how problems are being defined, highlight overlaps and differences, and identify the context(s) in which a particular index is useful. We also analyze the intended use, end-users, and geographic scale of application for each index. We find that risk assessment is the most common application (n = 25), with indices in this group typically focusing either on hazard identification (biophysical assessments) or vulnerability of human populations. Indices that measure freshwater ecological health are not explicitly linking these indicators to ecosystem services, and in fact the concept of ecosystem services is rarely (n = 3) used for indicator selection. Resource managers are the most common group of intended end-users (n = 25), but while 28 indices involved consultation with potential end-users, 11 did not specify an intended use. We conclude that indices can be applied as solution-oriented tools, evaluating scenarios and identifying tradeoffs among services and beneficiaries, rather than only assessing and monitoring existing conditions. Finally, earlier engagement of end-users is recommended to help researchers find the right balance among indices' salience, legitimacy, and credibility and thus improve their decision relevance.

Dynamic measurement of the force required to move a liquid drop on a solid surface

We measured the forces required to slide sessile drops over surfaces. The forces were measured by means of a vertical deflectable capillary stuck in the drop. The drop adhesion force instrument (DAFI) allowed the investigation of the dynamic lateral adhesion force of water drops of 0.1 to 2 μL volume at defined velocities. On flat PDMS surfaces, the dynamic lateral adhesion force increases linearly with the diameter of the contact area of the solid-liquid interface and linearly with the sliding velocity. The movement of the drop relative to the surfaces enabled us to resolve the pinning of the three-phase contact line to individual defects. We further investigated a 3D superhydrophobic pillar array. The depinning of the receding part of the rim of the drop occurred almost simultaneously from four to five pillars, giving rise to peaks in the lateral adhesion force.

Frequency-dependent deformation of liquid crystal droplets in an external electric field

Nematic droplets suspended in the isotropic phase of the same substance were subjected to alternating electrical fields of varying frequency. To keep the system at a constant nematic/isotropic volume ratio with constant droplet size, we carefully kept the temperature in the isotropic/nematic coexistence region, which was broadened by adding small amounts of a non-mesogenic liquid. Whereas the nematic droplets remained spherical at low (in the order of 10 Hz) and high frequencies (in the order of 1 kHz), at intermediate frequencies we observed a marked flattening of the droplets in the plane perpendicular to the applied field. Droplet deformation occurred both in liquid crystals (LCs) with positive and negative dielectric anisotropy. The experimental data can be quantitatively modelled with a combination of the leaky dielectric model and screening of the applied electric field due to finite conductivity.

Time-resolved X-ray microscopy of nanoparticle aggregates under oscillatory shear

Of all the current detection techniques with nanometre resolution, only X-ray microscopy allows imaging of nanoparticles in suspension. Can it also be used to investigate structural dynamics? When studying the response to mechanical stimuli, the challenge lies in its application with a precision comparable with the spatial resolution. In the first shear experiments performed in an X-ray microscope, this has been accomplished by inserting a piezo actuator driven shear cell into the focal plane of a scanning transmission X-ray microscope. Thus shear-induced re-organization of magnetite nanoparticle aggregates could be demonstrated in suspension. As X-ray microscopy proves suitable for studying structural change, new prospects open up in physics at small length scales.

Regulation of mesenchymal stem cell and chondrocyte differentiation by MIA

Melanoma inhibitory activity (MIA), also referred to as cartilage-derived retinoic acid-sensitive protein (CD-RAP), an 11-kDa secreted protein, is mainly expressed in cartilaginous tissue during embryogenesis and adulthood. Currently, the function of MIA in cartilage tissue is not understood. Here, we describe that MIA acts as a chemotactic factor on the mesenchymal stem cell line C3H10T1/2, stimulating cell migration significantly at concentrations from 0.24 to 240 ng/ml, while inhibiting cell migration at higher doses of 2.4 microg/ml. When analyzing the role of MIA during differentiation processes, we show that MIA by itself is not capable to induce the differentiation of murine or human mesenchymal stem cells. However, MIA influences the action of bone morphogenetic protein (BMP)-2 and transforming growth factor (TGF)-beta 3 during mesenchymal stem cell differentiation, supporting the chondrogenic phenotype while inhibiting osteogenic differentiation. Quantitative RT-PCR analysis revealed the up-regulation of the cartilage markers MIA, collagen type II and aggrecan in human mesenchymal stem cell (HMSC) cultures differentiated in the presence of MIA and TGF-beta 3 or BMP-2 when compared to HMSC cultures differentiated in the presence of TGF-beta 3 or BMP-2 alone. Further, MIA down-regulates gene expression of osteopontin and osteocalcin in BMP-2 treated HMSC cultures inhibiting the osteogenic potential of BMP-2. In the case of human primary chondrocytes MIA stimulates extracellular matrix deposition, increasing the glycosaminoglycan content. Therefore, we postulate that MIA is an important regulator during chondrogenic differentiation and maintenance of cartilage.

Phase separation in binary fluid mixtures with continuously ramped temperature

We consider the demixing of a binary fluid mixture, under gravity, which is steadily driven into a two-phase region by slowly ramping the temperature. We assume, as a first approximation, that the system remains spatially isothermal, and we examine the interplay of two competing nonlinearities. One of these arises because the supersaturation is greatest far from the meniscus, creating inversions of the density which can lead to fluid motion; although isothermal, this is somewhat like the Bénard problem (a single-phase fluid heated from below). The other is the intrinsic diffusive instability which results either in nucleation or in spinodal decomposition at large supersaturations. Experimental results on a simple binary mixture show interesting oscillations in heat capacity and optical properties, for a wide range of ramp parameters. We argue that these oscillations arise under conditions where both nonlinearities are important.

Mechanical tension in distraction osteogenesis regulates chondrocytic differentiation

Differentiation of chondrocytes to cells of osteoblastic phenotype occurs during an interim period of bone development, fracture repair and distraction osteogenesis. To study the relationship between tension-stress and chondrogenesis, uniaxial strains (0 microstrains, 2000 microstrains, 20000 microstrains, 200000 microstrains, 300000 microstrains) were applied in a rabbit model of mandibular distraction osteogenesis. The results demonstrated that cell differentiation, apoptosis and tissue development in the newly formed gap tissue showed a correlation to the applied strain magnitudes. Only strains of 20000 microstrains resulted in a statistically significant (P<0.05) formation of cartilage struts with embedded chondrocyte-like cells. However, chondrocyte-like cells were rarely detected in samples distracted at lower or higher strain magnitudes. Osteoblasts appeared to replace cartilaginous matrix by mineralized bone matrix. The phenotypic change from chondrocytes to osteoblasts was accompanied by a decreased proteoglycan synthesis. a change in the expression from type II collagen towards type I and involved asymmetric cell divisions and apoptotic cell death. Therefore, we suggest that mechanical strain is an external stimulus responsible for phenotypic cell alterations.

Bone loading pattern around implants in average and atrophic edentulous maxillae: a finite-element analysis

INTRODUCTION

Oral implants placed in the maxilla, especially the posterior region, have a lower success rate than those placed in the mandible. Poor bone quantity and quality have been suggested as a reason for this differential success rate.

OBJECTIVE

The purpose of this study was, therefore, to evaluate stress and strain distributions around loaded implants in the normal and atrophic maxilla by finite-element (FE) analyses.

MATERIAL

FE models of a solitary implant were generated to determine stresses and strains in the bone adjacent to the implant surface under loading conditions.

STUDY DESIGN

Different bony situations and implant lengths were used in a FE model. Static loads were applied axially and the resulting stresses and strains calculated.

RESULTS

Bone quality and quantity play a major role in decreasing bone strains adjacent to the implant surface under loading. It was found that stresses were more homogeneously distributed when more spongy bone was present. Decreased bone height was found to have less pronounced effects on strain and stress alterations than poor bone quality. Atrophic bony dimensions in combination with poor bone quality were associated with surface strains exceeding physiological levels (> 6,000 microstrains).

CONCLUSION

Our investigation indicates that supraphysiological bone strains adjacent to the implant surface should be expected under mechanical loading in the atrophic maxilla.

[Planning orthodontic surgery with the Hexapod system]

Treatment of maxillofacial dysgnathia using a combined surgical/orthodontic approach requires careful orthodontic and orthognathic diagnosis and treatment planning. In the present study, a system enabling on-line presentation of the necessary displacements of the jaw during surgery, while improving the accuracy of the planning, is described. Using the hexapod principle, it is possible to plan operations with six degrees of freedom and to measure the three-dimensional movements of jaws and jaw segments within the planning stage. Routinely prepared casts are employed for simulation of the operation. The displacements of the jaw are presented in a manner familiar to the orthodontic surgeon, namely in a surgical record. The accuracy achieved with the hexapod is superior to that achievable intra-operatively.

Antimicrobial resistance and bacterial identification utilizing a microelectronic chip array

Species-specific bacterial identification of clinical specimens is often limited to a few species due to the difficulty of performing multiplex reactions. In addition, discrimination of amplicons is time-consuming and laborious, consisting of gel electrophoresis, probe hybridization, or sequencing technology. In order to simplify the process of bacterial identification, we combined anchored in situ amplification on a microelectronic chip array with discrimination and detection on the same platform. Here, we describe the simultaneous amplification and discrimination of six gene sequences which are representative of different bacterial identification assays: Escherichia coli gyrA, Salmonella gyrA, Campylobacter gyrA, E. coli parC, Staphylococcus mecA, and Chlamydia cryptic plasmid. The assay can detect both plasmid and transposon genes and can also discriminate strains carrying antibiotic resistance single-nucleotide polymorphism mutations. Finally, the assay is similarly capable of discriminating between bacterial species through reporter-specific discrimination and allele-specific amplification. Anchored strand displacement amplification allows multiplex amplification and complex genotype discrimination on the same platform. This assay simplifies the bacterial identification process greatly, allowing molecular biology techniques to be performed with minimal processing of samples and practical experience.

Application of bone remodeling theories in the simulation of orthodontic tooth movements

A numerical model that calculates bone apposition and resorption around a tooth root on the basis of bone remodeling theories was developed to simulate orthodontic tooth movements. The model was used to calculate different kinds of orthodontic tooth movements, that were then compared with the expected movements based on clinical experience. For simulation of the movements the root of a canine was modeled in an idealized way in the form of an elliptical paraboloid and was processed with a finite element program. The finite element model was loaded with defined force systems. Two model assumptions were used to calculate the bone remodeling process. The mechanical loads firstly in the periodontal ligament and secondly in the alveolar bone were taken to simulate the following tooth movements: 1. mesial tipping around the center of resistance (force system at the bracket: isolated torque MY = 5 Nmm), 2. rotation around the long axis of the tooth (MZ = 5 Nmm), 3. uncontrolled tipping around the root tip (FX = 1 N, MZ = 5 Nmm), 4. canine retraction (FX = 1 N, MY = -9.5 Nmm, MZ = 5 Nmm), 5. and 6. extrusion/intrusion (FZ = +/- 0.5 N, MX = +/- 2.5 Nmm). Comparison with clinical experience was performed by calculating the orthodontic tooth movements based on the assumption of a fixed position of the center of resistance. It could be demonstrated that the numerical model of orthodontic bone remodeling can be used to calculate orthodontic tooth movements. However, the results are strongly dependent on the model assumptions. The model simulating the bone remodeling on the basis of the loading of the periodontal ligament delivers results that are in very good accordance with the biomechanical assumptions of the position of the center of resistance. However, marked side effects occurred with the second model, especially in the simulations of uncontrolled tipping, translation and intrusion/extrusion. Clinically, these side effects cannot be observed.

Prospective study on the reproducibility of cephalometric landmarks on conventional and digital lateral headfilms

The introduction of digital X-ray techniques offered a variety of new possibilities for digital image enhancement and exposure reduction. In order to compare the reproducibility of cephalometric landmarks on conventional and digital lateral headfilms 100 digital and 100 conventional lateral headfilms of patients attending our clinic were randomly selected. The digital cephalograms were obtained using storage phosphor plates in standard X-ray cassettes. All X-rays had been taken at 77 kV. For the digital images the mAs settings for conventional images minus 4 mAs were used. Two orthodontists traced each X-ray twice (21 reference points) at an interval of at least 1 week. The tracings were superimposed and the distances between the tracings of identical reference points were registered. The average reproducibility of cephalometric landmarks was significantly higher on the digitally obtained images, despite a reduction of radiation exposure of 23.7% in the digital images.

[Effect of implant geometry on strain distribution in peri-implant bone]

Recent developments and results in the field of mechanical bone stimulation have made it possible to define limits between physiological and non-physiological transmission of strength to the bone. Now it is necessary to investigate the different geometries of dental implants regarding biomechanical reliability. The aim of this study was to examine the distribution of strain on the bone along different basic forms of implants during loading using finite element analysis (FEA). The following implant designs were included in the study: cylinder, threaded cylinder, cylinder with steps, threaded cylinder with steps, and double-disk implants. All implants had a length of 12 mm and a diameter of 4 mm, the axial loading was defined as 300 N. Threaded implants showed more homogeneous distribution of strain than stepped implants, however, the maximum values were below the physiological range. Shortening of the implants led to an increase of the values, however, there was a zone of hypophysiological strain apically. Disk implants showed extremely low values at the disk margins, possibly due to the lack of physiological bone stimulus by the disks. Overall, none of the implants showed optimal distribution of strain, even though homogeneous strain distribution is decisive for long-term implant stability.

Experimental and finite element study of a human mandible

Knowledge of the complex biomechanical behaviour of the human mandible is of great importance in various clinical situations. Various approaches can be used to evaluate the physical behaviour of bony specimens. In the course of this study, we investigated mandibular deformation under mechanical loads in an experimental setting and compared them with results derived from finite element analysis (FEA). A special apparatus was developed to apply various forces under defined conditions on an explanted human mandible in vitro. Strains on the surface of the mandible were measured with strain gauges and subsequently a voxel based finite element mesh was generated. Strain patterns of the mandible were calculated in the FE analysis and matched with the experimental data. Comparing the numerical with the experimental data, we found a good correlation between in vitro measurements and mathematical modelling (correlation coefficient = 0.992). Then the FE model was used to evaluate mandibular biomechanics relative to aspects of load transfer, stress distribution and displacements. It is concluded that the applied procedure of generating the FE model is a valid and accurate, non-invasive method to predict different parameters of the complex biomechanical behaviour of human mandibles.

[Semi-automatic generation of finite element meshes fo dental preparations]

The mechanical properties and elastic behaviour of periodontal tissue are a decisive factor in understanding initial tooth mobility and bone remodelling processes in orthodontics. An experimental set-up was designed to precisely determine a tooth's elastic response to different loading conditions. Segments of pig's maxilla bearing separated molars were used, and their mechanical response to loading was recorded. Subsequently, finite element analysis (FEA) was performed on the basis of the experimental data. The combination of experimental and numerical methods was used to determine the material properties of the periodontal ligament (PDL). The geometries of the preparations were reconstructed and FE meshes generated semi-automatically with the aid of the special computer program, CAGOG (Computer Aided Generator for Orthodontic Geometries) to optimally match the experimental geometry. Nonlinear material parameters were determined for the PDL and verified by comparing experimental and numerical results obtained in other specimens with an error of about 10%. This good correlation indicates that the selected method of mesh generation is appropriate for creating realistic FE models that can be compared with experimental results.

[Experimental and finite-element models for the assessment of mandibular deformation under mechanical loading]

Biomechanical investigations of the mandible are difficult to perform due to a variety of conditions involved. For the appropriate reconstruction of biomechanical properties, a geometrically correct body model has to be established which fits to complex in vivo conditions. The aim of our study was to evaluate the use of finite-element models (FEM) for the assessment of mandibular deformation under mechanical loading. Explanted human mandibles (n = 5) were investigated by strain gauges to determine the individual strain distribution under mechanical loading. FEM analysis based on a computed tomograph (CT) was performed and the results were matched with the test data. Our study demonstrates only minor interindividual differences in the strain distribution for each load studied. The mechanical response in terms of deformation was found to depend mainly on gross geometrical properties and to a minor extent on the various other variables. At all positions the maximum principal strain was tensile, the minimum principal strain was compressive, and the absolute strain values were correlated with the magnitude of the applied force. CT-based FEM analysis revealed the utility of mathematical models to approximate simulated data our experimental results. Hence, FEM analysis is a non-invasive tool in the prediction of biomechanical behaviour of individual mandibles and therefore may help in trauma reconstruction and treatment planning.

Determination of the centre of resistance in an upper human canine and idealized tooth model

The purpose of this investigation was to analyse the influence of geometric and material parameters of a human canine on initial tooth mobility, and the stress and strain profiles in the periodontal ligament. While the material parameters of tooth and bony structures are known within an uncertain limit of approximately a factor of 10, values reported for the elasticity parameters of the periodontal ligament differ significantly. In the course of this study, bilinear behaviour was assumed for the mechanical property of the periodontium. The finite element model of an elliptical paraboloid was created as an approximation to the geometry of a human canine to reduce calculation time and to determine influences of the geometry on numerical results. The results were compared with those obtained for a realistic human canine model. The root length of both models was 19.5 mm. By calculating pure rotational and pure tipping movements, the centre of resistance (CR) was determined for both models. They were located on the long axis of the tooth approximately 7.2 mm below the alveolar crest for the idealized model and 8.2 mm for the canine model. Thus, the centre of resistance of a human canine seems to be located around two-fifths of the root length from the alveolar margin. Using these results, uncontrolled tipping (1 N of mesializing force and 5 Nmm of derotating momentum), as well as pure translation (additionally about 10 Nmm of uprighting momentum) were calculated. Comparing the idealized and the realistic models, the uncontrolled tipping was described by the parabolic-shaped model within an accuracy limit of 10 per cent as compared with the canine model, whereas the results for bodily movement differed significantly showing that it is very difficult to achieve a pure translation with the realistic canine model.

Simulation of orthodontic tooth movements. A comparison of numerical models

Orthodontic tooth movements are based on the ability of bone to react to mechanical stresses with the apposition and resorption of alveolar bone. Currently, the underlying biophysical, biochemical, and cellular processes are the subject of numerous studies. At present, however, an analytical description of orthodontic tooth movements including all components of the processes involved seems to be impossible. It was the aim of the present study to develop a mechanics-based phenomenological model capable of describing the alveolar bone remodeling. Thus, 2 different models were developed. The first is based on the assumption that deformations of the periodontal ligament (PDL) are the key stimulus to starting orthodontic tooth movement. The second supposes that deformations of the alveolar bone are the basis of orthodontic bone remodeling. Both models were integrated into a finite element package calculating stresses, strains and deformations of tooth and tooth supporting structures and from this simulating the movement of the tooth and its alveolus through the bone. Clinically induced canine retractions in 5 patients as well as force systems were exactly measured and the tooth movements were simulated using both models. The results show that the first model allows reliable simulation of orthodontic tooth movements, whereas the second is to be rejected.

Successful use of the nocturnal urine alarm for diurnal enuresis

We report the effects of using a urine alarm, typically employed for nocturnal enuresis, to treat chronic diurnal enuresis in a 15-year-old female resident at Boys' Town. The results of an ABAB reversal design indicate that the alarm eliminated wetting in both treatment phases and that continence was maintained at 3- and 6-month follow-up.

Adrenocortical insufficiency in Rhodesian sleeping sickness is not attributable to suramin

Suramin, a polysulphonated naphthylurea used in the treatment of human African trypanosomiasis (HAT), is known to cause adrenocortical insufficiency in doses exceeding the quantity used for treatment of HAT. We have previously reported that Trypanosoma brucei rhodesinese infection causes a combined central and peripheral adrenal insufficiency. To evaluate whether suramin therapy acts as an additional adrenotoxic factor, we assessed adrenocortical function in 72 patients suffering from HAT at different times during treatment with either suramin or melarsoprol by a rapid adrenocorticotropic hormone test. We found a significantly diminished peak cortisol response to stimulation in the acutely ill patients (P = 0.001), indicating impaired adrenocortical function, as well as a high incidence of partial adrenocortical insufficiency (27%). During and after trypanocidal therapy the incidence of partial adrenal insufficiency gradually declined (to 25% and 18% respectively). Stimulated peak cortisol levels did not differ significantly between patients receiving suramin and those given melarsoprol. No correlation was found between serum suramin concentration and the cortisol response to stimulation (r = 0.09, P = 0.47). Thus we conclude that suramin in trypanocidal doses neither causes nor worsens the adrenocortical dysfunction observed in Rhodesian HAT.

Hypothalamic chordoma. Case report

The case is reported of a 51-year-old woman found to have a hypothalamic mass with the histological features typical of chordoma. This represents the first description of a chordoma arising within the brain.

Impairment of adrenocortical function associated with increased plasma tumor necrosis factor-alpha and interleukin-6 concentrations in African trypanosomiasis

African sleeping sickness (SS) is a severe, potentially lethal parasitic disease. The treatments of choice are the antiparasitic agents suramin, which is adrenotoxic, and/or melarsoprol. We evaluated the functional integrity of the hypothalamic-pituitary-adrenal (HPA) axis of patients with SS before, during, and after therapy with suramin and/or melarsoprol, in two sequential stages. First, we employed the standard adrenocorticotropic hormone (ACTH) 1-24 stimulation test (250 micrograms i.v.) to assess the maximal adrenocortical responsiveness of 69 patients with SS and 38 normal controls. We demonstrated paradoxically subnormal cortisol responses before suramin therapy [net cortisol response 60 min after stimulation: 10.5 +/- 2.9 (mean +/- SE) vs. 17.5 +/- 1.0 micrograms/dl for controls, p = 0.004], with 27% of the patients falling within the adrenal insufficiency range (stimulated cortisol concentration < 20 micrograms/dl). These responses subsequently and unexpectedly improved with suramin and/or melarsoprol therapy. Second, we performed a human corticotropin-releasing hormone (hCRH) test (100 micrograms i.v.) in 68 additional patients with SS and 14 control subjects to examine whether the glucocorticoid deficiency observed was primary and/or secondary. Compared to controls, the ACTH and cortisol responses to hCRH were blunted (ACTH after 60 min: 29 +/- 7 vs. 58 +/- 8 pg/ml in controls, p = 0.014; cortisol: 15.2 +/- 1.5 vs. 19.6 +/- 0.7 micrograms/dl, p = 0.018), suggesting the presence of secondary adrenal insufficiency. There was improvement of both ACTH and cortisol responsiveness to hCRH with therapy, with cortisol recovery occurring before ACTH, suggesting an additional primary component of adrenal dysfunction in these patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Thyroid dysfunction in African trypanosomiasis: a possible role for inflammatory cytokines

OBJECTIVE

Sleeping sickness (African trypanosomiasis) is an anthropozoonosis transmitted by the tsetse fly. The treatments of choice are the antiparasitic agents suramin and/or melarsoprol. Experimental infection of animals with Trypanosoma brucei results in inflammatory lesions in the pituitary and/or the thyroid gland. In biochemical terms, these animals have hypothyroidism. We evaluated the functional integrity of the hypothalamic-pituitary-thyroid axis in patients with African trypanosomiasis before, during and after specific therapy.

DESIGN

Prospective, controlled, cross-sectional study.

PATIENTS AND MEASUREMENTS

Sixty-five patients with sleeping sickness (31 female, 34 male; aged 18-66; 32 with haemolymphatic sleeping sickness receiving suramin i.v., 33 with cerebral sleeping sickness receiving melarsoprol) and 13 control subjects (6 female, 7 male; aged 21-60) were enrolled in a cross-sectional study after giving informed consent. Fourteen patients were studied shortly after admission for sleeping sickness, 19 in the middle of the course of treatment, 18 at the end of the 5-week treatment period, and 14 patients after cure. All subjects underwent a TRH stimulation test at 1200 with bolus injection of 400 micrograms TRH i.v. Blood was drawn for determination of fT3, fT4, TSH, rT3, TNF-alpha, IL-1 and IL-6 at 0 minutes and TSH at 60 minutes. All hormones and cytokines were determined by RIA or ELISA.

RESULTS

Baseline TSH concentrations (mean +/- SEM) were elevated in unmedicated patients with sleeping sickness compared to normal subjects (2.6 +/- 0.4 vs 1.4 +/- 0.2 mU/l; P = 0.01), whereas fT3 (2.7 +/- 0.5 vs 5.8 +/- 0.3 pmol/l; P = 0.0002) and fT4 concentrations (10.3 +/- 1.2 vs 15.4 + 0.8 pmol/l; P = 0.007) were low. Stimulated TSH concentrations did not significantly differ from normal controls. Reverse T3 concentration in patients with sleeping sickness were normal (2.2 +/- 0.3 vs 2.4 +/- 0.2 nmol/l; P = NS). During the course of treatment, baseline TSH, fT3 and fT4 concentrations slowly returned to normal and were indistinguishable from controls after cure. Plasma concentrations of TNF-alpha (16.0 +/- 4.1 vs 2.9 +/- 1.4 ng/l in controls; P = 0.003) and interleukin-6 (19.2 +/- 7.3 vs 1.3 +/- 0.2 ng/l; P = 0.0001), but not interleukin-1 beta (2.0 +/- 0.2 vs 0.9 +/- 0.2, ng/l P = NS), were elevated, when thyroid function impairment and disease activity were at their maximum, but gradually decreased into the normal range with therapy. We found a negative correlation between baseline cytokine concentrations and fT3 concentrations (TNF-alpha: r = -0.34, P = 0.003; IL-6: r = -0.43, P = 0.0001).

CONCLUSIONS

We conclude that unmedicated sleeping sickness is associated with significant impairment of thyroid function, which is reversed with specific therapy. Elevated TSH concentrations and low fT3 and fT4 concentrations suggest primary hypothyroidism in patients with sleeping sickness. However, an additional pituitary and/or hypothalamic component cannot be excluded. This impairment may be due to the elevated plasma cytokine concentrations found in these patients or may be the result of parasitic thyroiditis.

[Prevention of formaldehyde-induced occupational dermatoses in health care personnel]

Prevention of Occupational Dermatoses due to Formaldehyde in Employees of the Public Health System Occupational dermatoses lead all occupational diseases in employees of the Public Health and Social System in the district of Schwerin from 1977 to 1985. Disinfectants with formaldehyde which mainly produced allergic dermatoses were the main reasons. By substitution of formaldehyde as disinfectant and the accomplishing of contact-free technologies for cleaning purposes, occupational skin diseases in employees of the Public Health and Social System could obviously be reduced.

[Work hygiene study on dust from processing of Ni-Cr and Co-Cr alloys in the dental laboratory]

The work hygienical limit rates are with processing of Gisadent NCA and KCM essentially exceeded without a suited exhaustion at the working place. The efficiency of napkin and protection shield is limited. An effective exhaustion device is required.

An evaluation of a new test kit to screen for galactosemia

A new galactosemia screening kit has been evaluated. The kit employs the Yoshida modification of the Paigen et al. Escherichia coli bacteriophage assay and is produced by Eiken Co. Ltd. of Japan. The assay estimates galactose and galactose-1-phosphate in dried blood specimens. The kit is sufficiently sensitive to detect possible heterozygotes as well as possible homozygotes.