Microcosm experiment combined with process-based modeling reveals differential response and adaptation of aquatic primary producers to warming and agricultural run-off.

Fertilizers, pesticides and global warming are threatening freshwater aquatic ecosystems. Most of these are shallow ponds or slow-flowing streams or ditches dominated by submerged macrophytes, periphyton or phytoplankton. Regime shifts between the dominance of these primary producers can occur along a gradient of nutrient loading, possibly triggered by specific disturbances influencing their competitive interactions. However, phytoplankton dominance is less desirable due to lower biodiversity and poorer ecosystem function and services. In this study, we combined a microcosm experiment with a process-based model to test three hypotheses: 1) agricultural run-off (ARO), consisting of nitrate and a mixture of organic pesticides and copper, differentially affects primary producers and enhances the risk of regime shifts, 2) warming increases the risk of an ARO-induced regime shift to phytoplankton dominance and 3) custom-tailored process-based models support mechanistic understanding of experimental results through scenario comparison. Experimentally exposing primary producers to a gradient of nitrate and pesticides at 22°C and 26°C supported the first two hypotheses. ARO had direct negative effects on macrophytes, while phytoplankton gained from warming and indirect effects of ARO like a reduction in the competitive pressure exerted by other groups. We used the process-based model to test eight different scenarios. The best qualitative fit between modeled and observed responses was reached only when taking community adaptation and organism acclimation into account. Our results highlight the importance of considering such processes when attempting to predict the effects of multiple stressors on natural ecosystems.

Warming lowers critical thresholds for multiple stressor-induced shifts between aquatic primary producers.

In aquatic ecosystems, excessive nutrient loading is a global problem that can induce regime shifts from macrophyte- to phytoplankton-dominated states with severe consequences for ecosystem functions. Most agricultural landscapes are sites of nutrient and pesticide loading, which can interact with other stressors (e.g., warming) in additive, antagonistic, synergistic or reversed forms. The effects of multiple stressors on the resilience of macrophyte-dominated states and on critical thresholds for regime shifts are, however, unknown. We test the effects of individual and combined stressors of warming, nitrate, and various pesticides typically found in agricultural run-off (ARO) on the growth of macrophytes, periphyton, and phytoplankton in microcosms. We applied a one-level replicated design to test whether ARO induces a regime shift and a multifactorial dose-response design to model stressor thresholds and disentangle stressor interactions along a gradient. The individual stressors did not induce a regime shift, but the full ARO did. Nitrate and pesticides acted synergistically, inducing a shift with increasing phytoplankton biomass and decreasing macrophyte biomass. Warming amplified this effect and lowered critical thresholds for regime shifts. Shallow aquatic ecosystems in agricultural landscapes affected by global warming thus increasingly risk shifting to a turbid, phytoplankton-dominated state, and negatively impacting ecosystem service provisioning. Multiple stressor interactions must be considered when defining safe operating spaces for aquatic systems.

Multiple-stressor exposure of aquatic food webs: Nitrate and warming modulate the effect of pesticides.

Shallow lakes provide essential ecological and environmental services but are exposed to multiple stressors, including agricultural runoff (ARO) and climate warming, which may act on different target receptors disrupting their normal functioning. We performed a microcosm experiment to determine the individual and combined effects of three stressors-pesticides, nitrate and climate warming-on two trophic levels representative of communities found in shallow lakes. We used three submerged macrophyte species (Myriophyllum spicatum, Potamogeton perfoliatus, Elodea nuttallii), eight benthic or pelagic microalgal species and three primary consumer species (Daphnia magna, Lymnaea stagnalis, Dreissena polymorpha) with different feeding preferences for benthic and pelagic primary producers. Eight different treatments consisted of a control, only nitrate, a pesticide cocktail, and a combination of nitrate and pesticides representing ARO, each replicated at ambient temperature and +3.5°C, mimicking climate warming. Pesticides negatively affected all functional groups except phytoplankton, which increased. Warming and nitrate modified these effects. Strong but opposite pesticide and warming effects on Myriophyllum drove the response of the total macrophyte biomass. Nitrate significantly suppressed Myriophyllum final biomass, but not overall macrophyte and microalgal biomass. Nitrate and pesticides in combination caused a macrophyte decline, and the system tipped towards phytoplankton dominance. Strong synergistic or even reversed stressor interaction effects were observed for macrophytes or periphyton. We emphasize the need for more complex community- and ecosystem-level studies incorporating multiple stressor scenarios to define safe operating spaces.

Disentangling the direct and indirect effects of agricultural runoff on freshwater ecosystems subject to global warming: A microcosm study.

Aquatic ecosystems are exposed to multiple stressors such as agricultural run-off (ARO) and climate-change related increase of temperature. We aimed to determine how ARO and the frequency of its input can affect shallow lake ecosystems through direct and indirect effects on primary producers and primary consumers, and whether warming can mitigate or reinforce the impact of ARO. We performed a set of microcosm experiments simulating ARO using a cocktail of three organic pesticides (terbuthylazine, tebuconazole, pirimicarb), copper and nitrate. Two experiments were performed to determine the direct effect of ARO on primary producers (submerged macrophytes, periphyton and phytoplankton) and on the grazing snail Lymnaea stagnalis, respectively. Three different ARO concentrations added as single doses or as multiple pulses at two different temperatures (22°C and 26°C) were applied. In a third experiment, primary producers and consumers were exposed together to allow trophic interactions. When functional groups were exposed alone, ARO had a direct positive effect on phytoplankton and a strong negative effect on L. stagnalis. When exposed together, primary producer responses were contrasting, as the negative effect of ARO on grazers led to an indirect positive effect on periphyton. Periphyton in turn exerted a strong control on phytoplankton, leading to an indirect negative effect of ARO on phytoplankton. Macrophytes showed little response to the stressors. Multiple pulse exposure increased the effect of ARO on L. stagnalis and periphyton when compared with the same quantity of ARO added as a single dose. The increase in temperature had only limited effects. Our results highlight the importance of indirect effects of stressors, here mediated by grazers and periphyton, and the frequency of the ARO input in aquatic ecosystems.

[Rheumatoid arthritis-mimics : When appearances are deceptive]. / Rheumatoide Arthritis ­ Mimics : Wenn der Schein trügt.

Rheumatology represents a discipline full of differential diagnoses. Even for classical diseases, such as rheumatoid arthritis as the most frequent chronic inflammatory joint disease and described so clearly in many textbooks, it is not uncommon that it can be a diagnostic challenge in daily practice. This applies to arthritic joint involvement and also to frequently associated extra-articular manifestations. The patient history and results of the clinical examination are essential; however, laboratory and imaging findings often make a significant contribution to confirming the diagnosis, especially in early phases of the disease. This article, which makes no claims to completeness, focuses on diseases that in the opinion of the authors can imitate rheumatoid arthritis due to similar joint and other organ manifestations. These include metabolic, inflammatory infective and non-infective as well as tumorous diseases. A misinterpretation as rheumatoid arthritis as a rule leads to long-term and severe consequences for affected patients. Thus, the diagnosis of rheumatoid arthritis should be questioned and re-evaluated in cases of unusual accompanying symptoms, atypical course of disease and a lack of response to standard treatment approaches.

Hydrodynamics Alter the Tolerance of Autotrophic Biofilm Communities Toward Herbicides.

Multiple stressors pose potential risk to aquatic ecosystems and are the main reasons for failing ecological quality standards. However, mechanisms how multiple stressors act on aquatic community structure and functioning are poorly understood. This is especially true for two important stressors types, hydrodynamic alterations and toxicants. Here we perform a mesocosm experiment in hydraulic flumes connected as a bypass to a natural stream to test the interactive effects of both factors on natural (inoculated from streams water) biofilms. Biofilms, i.e., the community of autotrophic and heterotrophic microorganisms and their extracellular polymeric substances (EPS) in association with substratum, are key players in stream functioning. We hypothesized (i) that the tolerance of biofilms toward toxicants (the herbicide Prometryn) decreases with increasing hydraulic stress. As EPS is known as an absorber of chemicals, we hypothesize (ii) that the EPS to cell ratio correlates with both hydraulic stress and herbicide tolerance. Tolerance values were derived from concentration-response assays. Both, the herbicide tolerance and the biovolume of the EPS significantly correlated with the turbulent kinetic energy (TKE), while the diversity of diatoms (the dominant group within the stream biofilms) increased with flow velocity. This indicates that the positive effect of TKE on community tolerance was mediated by turbulence-induced changes in the EPS biovolume. This conclusion was supported by a second experiment, showing decreasing effects of the herbicide to a diatom biofilm (Nitzschia palea) with increasing content of artificial EPS. We conclude that increasing hydrodynamic forces in streams result in an increasing tolerance of microbial communities toward chemical pollution by changes in EPS-mediated bioavailability of toxicants.

Tailored disorder in calcite organization in tergite cuticle of the supralittoral isopod Tylos europaeus Arcangeli, 1938.

The crustacean cuticle forms skeletal elements consisting of chitin-protein fibrils reinforced by amorphous and crystalline calcium carbonate and phosphate minerals. The edges of skeletal elements are of particular interest. They are subject to repeated strain and stress because they form transitions to the arthrodial membranes connecting them. These allow for relative movements of skeletal elements. In this study, we investigate structure, chemical composition, mineral organization and local mechanical properties of the anterior and posterior edges of the tergite cuticle in the conglobating beach isopod Tylos europaeus and compare these with the protective dorsal region of the tergites. The distribution of mineral phases at the edges resembles that of dorsal regions of the tergites. At the transition with the unmineralized arthrodial membrane the calcite containing distal exocuticle is replaced by epicuticular material and the subjacent cuticular layers containing amorphous calcium carbonate become enriched with amorphous calcium phosphate. At the edges, the local elastic modulus and hardness values are significantly lower compared to dorsal regions of the tergite cuticle, for both, the calcite and the amorphous mineral containing layers. The calcite within the tergite cuticle is assembled in different texture patterns: (i) almost random co-orientation, (ii) almost single crystalline calcite, and (iii) a graded organization. Calcite organization and co-orientation strength is highly variable, not only on very few tens of micrometres, but also between regions with different skeletal functionality. Our results show that besides structure and composition, patterns of calcite organization contribute to the hierarchical architecture and functionality of biological composites.

[Improved early diagnostics of rheumatic diseases : Monocentric experiences with an open rheumatological specialist consultation]. / Verbesserte Frühdiagnostik rheumatischer Erkrankungen : Monozentrische Erfahrungen mit einer offenen fachärztlich rheumatologischen Sprechstunde.

AIM OF THE PROJECT: To establish an open rheumatological outpatient consultation service for early diagnosis of inflammatory rheumatic diseases and initiation of further diagnostics and treatment. METHODS: In 2015 an open consultation service was initiated for patients with signs of an early rheumatic disease after referral by primary care physicians. Patients could attend once a week without the need for a prior appointment if they fulfilled at least one of the following criteria: positive rheumatoid factor, increased CRP, anti-CCP antibody or antinuclear antibody, joint pain or back pain for over 3 months, swollen joints, fever of unknown origin or acute muscle pain with or without headache of unknown origin. This article presents the results of the retrospective descriptive data analysis of the first 2 years of this project. RESULTS: A total of 1262 patients were treated with an average of approximately 20 patients per consultation. In nearly half of the patients an inflammatory rheumatological disease could be diagnosed and immediate diagnostic and treatment measures could be initiated. The diagnostic delay for patients with rheumatoid arthritis was 12 weeks, for patients with polymyalgia rheumatica 11 weeks and for patients with psoriatic arthritis or axial spondylarthritis 18 and 44 weeks, respectively. The time expenditure was a total of 4-5 h per week for an experienced rheumatologist and a specialized rheumatology nurse. CONCLUSION: Through this open rheumatological outpatient consultation a low threshold opportunity for the early diagnosis of rheumatologic diseases could be established. The diagnostic delay for many rheumatological diseases could be considerably shortened. Cooperation with rheumatologists in private practice guaranteed the subsequent specialized rheumatological care of the identified patients in the early stages of their illness.

[Rare manifestations of axial skeleton gouty arthropathy]. / Seltene Manifestationen der Arthritis urica am Achsenskelett.

Clinical manifestations of gouty arthropathy are usually acute inflammatory arthritis, bursitis and accumulation of urate crystals in the form of tophi. Manifestations on the axial skeleton are also known and have been described but occur infrequently and for this reason play a subordinate role in the awareness of rheumatologists. With dual energy computed tomography (CT) gout tophi can be detected even in unusual regions or regions that are difficult to access for puncturing. We describe two rare cases of gouty arthropathy of the axial skeleton in a 76-year-old male patient with spinal involvement and in a 53-year-old female patient with involvement of the sacroiliac joint. In both cases the diagnosis was achieved with dual energy CT.

Functional adaptation of crustacean exoskeletal elements through structural and compositional diversity: a combined experimental and theoretical study.

The crustacean cuticle is a composite material that covers the whole animal and forms the continuous exoskeleton. Nano-fibers composed of chitin and protein molecules form most of the organic matrix of the cuticle that, at the macroscale, is organized in up to eight hierarchical levels. At least two of them, the exo- and endocuticle, contain a mineral phase of mainly Mg-calcite, amorphous calcium carbonate and phosphate. The high number of hierarchical levels and the compositional diversity provide a high degree of freedom for varying the physical, in particular mechanical, properties of the material. This makes the cuticle a versatile material ideally suited to form a variety of skeletal elements that are adapted to different functions and the eco-physiological strains of individual species. This review presents our recent analytical, experimental and theoretical studies on the cuticle, summarising at which hierarchical levels structure and composition are modified to achieve the required physical properties. We describe our multi-scale hierarchical modeling approach based on the results from these studies, aiming at systematically predicting the structure-composition-property relations of cuticle composites from the molecular level to the macro-scale. This modeling approach provides a tool to facilitate the development of optimized biomimetic materials within a knowledge-based design approach.

Electron microscopic and preparative methods for the analysis of isopod cuticle.

The crustacean cuticle consists of a complex organic matrix and a mineral phase. The physical and chemical properties of the cuticle are corellated to the specific functions of cuticular elements, leading to a large variety in its structure and composition. Investigation of the structure-function relationship in crustacean cuticle requires sophisticated methodological tools for the analysis of different aspects of the cuticular architecture. In the present paper we report improved preparation methods that, in combination with various electron microscopic techniques, have led to new insights of cuticle structure and composition in the tergite cuticle of Porcellio scaber. We used thin sections of non-decalcified tergites and decalcified resin embedded material for transmission electron microscopy and scanning transmission electron microscopy. Etched sagittal planes of bulk tergite samples were analysed with field emission scanning electron microscopy. We have found a distinct distal region within the exocuticle that differs from the subjacent proximal exocuticle in the arrangement of fibres. Within this distal exocuticle chitin-protein fibrils assemble to fibres with diameters between 15 and 50 nm that are embedded in a mineral matrix. In the proximal exocuticle and the endocuticle fibrils do not assemble to fibres and are surrounded by mineral individually. Furthermore, we show that the pore canals are filled with mineral, and demonstrate that mild etching of polished sagittal cuticle surfaces reveals regions containing mineral of diverse solubility.

Toward a data-driven evaluation of the 2010 American College of Rheumatology/European League Against Rheumatism criteria for rheumatoid arthritis: is it sensible to look at levels of rheumatoid factor?

OBJECTIVE: Recently, new classification criteria for rheumatoid arthritis (RA) have been devised by methodology that used first a quantitative approach (data from databases), then a qualitative approach (consensus; based on paper patients), and finally a common sense-based approach (evaluation of the former phases). Now the individual items that make up these criteria are being evaluated. This study was undertaken to analyze the item "autoantibodies," in particular rheumatoid factor (RF) level. METHODS: Three separate cohorts comprising a total of 972 patients with undifferentiated arthritis were studied for RA development (according to the 1987 American College of Rheumatology criteria) and arthritis persistence. The positive predictive value (PPV), negative predictive value (NPV), and likelihood ratios (LRs) were compared between different levels of RF and the presence of anti-citrullinated protein antibody (ACPA). A similar comparison was made in 686 RA patients for the rate of joint destruction and achievement of sustained disease-modifying antirheumatic drug-free remission during 7 years of followup. The variation in RF levels obtained by different measurement methods in the same RF-positive sera was explored. RESULTS: Compared to high RF levels, presence of ACPA had a better balance between positive LR and negative LR and between PPV and NPV for RA development. The additive value of ACPA assessment after testing for RF level was higher than vice versa. The association between high RF level and RA severity was not as strong as that between ACPA antibodies and RA severity. The RF level obtained by different methods in the same patients' sera varied considerably. CONCLUSION: Our findings indicate that determination of RF level is subject to large variation; high RF level has limited additive prognostic value compared to ACPA positivity. Thus, omitting RF level and using RF presence, ACPA presence, and ACPA level may improve the 2010 criteria for RA.

[Therapeutic strategies in rheumatoid arthritis]. / Therapiestrategien bei rheumatoider Arthritis.

Rheumatoid arthritis is the most common chronic inflammatory-rheumatic joint disease. If untreated, patients develop radiologically detectable progressive joint destruction. Rheumatoid arthritis has considerable socioeconomic importance, since a majority of patients are affected at employable age and can be significantly disabled over the course of the disease. Therefore, an appropriate early intervention with disease modifying anti-rheumatic drugs as well as ergo- and physiotherapy plays an important role for the prognosis. In the past few years, the introduction of novel drugs has improved the treatment opportunities markedly. This progress was the basis for new treatment strategies of tight disease control with the goal of disease remission.

[The development of health information with the involvement of consumers at the German Institute for Quality and Efficiency in Health Care (IQWiG)]. / Die Entwicklung von Gesundheitsinformationen unter Beteiligung von Bürgerinnen und Bürgern am Institut für Qualität und Wirtschaftlichkeit im Gesundheitswesen (IQWiG).

The German Institute for Quality and Efficiency in Health Care (IQWiG) began publishing free bi-lingual (German/English) evidence-based health information in February 2006 on the website, http://www.gesundheitsinformation.de http://www.informedhealthonline.org . The Institute aims to be a patient-centred and non-directive provider of health information to the public and patients. The point of view and information needs of the public are a central element in the development of health information. People can be involved implicitly or explicitly. People can participate directly or explicitly in health information, for example, by suggesting a topic, by helping shape the content and during the development process. We do this in several ways, including surveys, consultation with consumer representatives as well as through user-testing and reader online rating. In addition, implicit involvement of patients occurs indirectly through consideration of the experiences and information needs of patients via an analysis of qualitative research. A challenge here is the generalisability of information derived from research in other cultures. The Institute monitors methodological developments in the area of patient and health information, to keep its methods up-to-date. In addition, the colleagues involved in this work participate in an in-house training program on patient-centred health information.

[New biologics and orally available compounds. What is still in the pipeline?]. / Neue Biologika und oral verfügbare neue Medikamente. Was ist noch in der Pipeline?

Biologics have revolutionized the treatment of inflammatory joint disease in the last decade. By precisely targeting and inhibiting inflammatory cytokines as well as the blockade of cells centrally integrated in the immune system, inhibition of inflammation has become possible which had been unthinkable before. The medical need to improve our current approach with biologics even more is based on three observations: (1) even though the clinical effect of a given biologic is evident in the majority of patients, not all show a satisfactory response, (2) the blockade of important mediators of the immune system bears the risk of infection and potentially malignant events and (3) all current biologics need to be administered parenterally. The present review describes several innovative biologics and low molecular weight compounds which are currently being investigated in clinical trials in patients suffering from inflammatory rheumatic conditions. Some of them may become a part of our growing armamentarium to treat these diseases which still represent a major burden to the patients and society.

[Does TNF play a role in the pathogenesis of solid tumors?]. / Spielt TNF in der Pathogenese von soliden Tumoren eine Rolle?

Tumor necrosis factor (TNF)-alpha blocking agents play an important role in rheumatology. For this reason, questions about the pathogenic characteristics of TNF in carcinogenesis are of the utmost importance. The observation that TNF leads to necrosis in tumor tissue gave rise to the hope that an agent had been identified for the treatment of malignant tumors. However, this expectation remained unfulfilled, not the least due to the toxicity of systemically applied TNF. In addition, TNF is produced by many tumor cells. There is evidence that for some tumors TNF promotes tumor growth, invasiveness and metastasis. It is quite possible, therefore, that the inhibition of TNF-alpha has an inhibitive effect on carcinogenesis and/or tumor progression. In 2009 the US Food and Drug Administration (FDA) issued a cancer warning for the use of TNF inhibitors in children and adolescents. There is still some controversy as to whether TNF blocking therapy, co-medication or the rheumatic disease itself leads to an increased cancer risk in these young patients. In adults, safety information so far available suggests a favorable risk-benefit profile for the long-term use of TNF inhibitors. However, many questions remain unanswered as to the role TNF itself plays in the pathogenesis of solid tumors.

[Effects of electrostimulation (Veinoplus) on lower limbs venous insufficiency-related symptoms during pregnancy. Preliminary study]. / Effets de l'électrostimulation par Veinoplus sur les troubles circulatoires des membres inférieurs chez la femme enceinte. Etude préliminaire.

OBJECTIVE: To assess if electrostimulation of lower limbs relieves lower limbs venous insufficiency-related symptoms during pregnancy. PATIENTS AND METHODS: A two-step study was conducted. First, a monocentric prospective preliminary study including 30 pregnant women was conducted to assess the effects of electrostimulation on fetal monitoring and uterine contractions. Then, a multicentric prospective non-randomised study including 58 pregnant women with a gestational age between 23 and 33 weeks of amenorrhoea was conducted to evaluate the electrostimulation treatment. This evaluation was based on a clinical examination performed pre- and post-treatment, a CIVIQ questionnaire filled out pre- and post-treatment and a daily diary filled out by the patient during treatment duration. Treatment duration was 21 days including two daily treatment sequences of 20 min. Three groups of patients were identified based on initial intensity of venous insufficiency-related symptoms (group 1 minor symptoms, group 2 moderate symptoms, group 3 severe symptoms). RESULTS: Preliminary study showed no interferences between electrostimulation and fetal cardiac rhythm, uterine contractions and maternal uterine and fetal umbilical arteries Doppler. Concerning the evaluation of the electrostimulation: in group 1, electrostimulation significantly reduced heavy legs sensation (p<0,001) and calves pain (p=0,02) between the beginning and the end of the treatment. The four scores calculated with the CIVIQ questionnaire decreased after treatment and a significant reduction was noted for generalised pain feeling (p=0,04) and psychological impact (p=0,03). In group 2, a significant decrease was noted for tiredness (p<0,001), heavy legs sensation (p<0,001), calves pain (p<0,001) and edema (p=0,02) between the beginning and the end of the treatment. The four scores calculated with the CIVIQ questionnaire significantly decrease after 21 days of treatment. In group 3, a significant decrease of heavy legs sensation (p=0,03) and calves and malleoli perimeters (p<0,05) was noted. After 21 days of treatment, the four scores calculated with the CIVIQ questionnaire significantly decrease (p<0,05). When comparing the three groups, beneficial effects of the treatment are most marked in group 2 regarding subjective symptoms, CIVIQ questionnaire scores and leg pain. According to the patients, effectiveness and tolerance of the treatment ranged from good to excellent in the three groups. DISCUSSION AND CONCLUSION: Electrostimulation is an effective and well-tolerated treatment of lower limbs venous insufficiency-related symptoms in pregnant women. Its use during pregnancy did not show any effects on fetus and pregnancy.

Lucy Wills (1888-1964): the life and research of an adventurous independent woman.

Lucy Wills was one of a pioneering generation of women in medicine and medical research in England. After a double first honours degree in botany and geology from Cambridge in 1911, she travelled to South Africa, where she worked as a nurse during the First World War. Wills then gained a medical degree in London in 1920. By the late 1920s she had developed an interest in haematology and began travelling to India to investigate pernicious anaemia in pregnancy. There she identified a substance often called 'the Wills' factor', which was later recognised as folic acid. Wills undertook a placebo trial of routine iron supplementation in pregnant women during the Second World War, hampered, but not stopped, by bombing. In retirement, she continued to study nutritional effects on health in South Africa and Fiji.

[Qualitative and quantitative analysis of urolithiasis with the Rietveld method (x-ray diffraction)]. / Genaue qualitative und quantitative Harnsteinanalyse mit Hilfe der Rietveld-Methode (Röntgendiffraktion).

BACKGROUND: The Rietveld method is one of the most innovative and most important applications in x-ray diffraction and has now, for the first time, been applied to standard-free precise quantitative crystallographic analysis of urinary stones. MATERIAL AND METHODS: The capability of the Rietveld method was demonstrated by analysis of a synthetic mixture of five typical urinary stones: whewellite, hydroxylapatite, brushite, struvite, and uric acid, with 20 weight % for each pure component. RESULTS: The quantitative phase analysis (Rietveld method) yielded a mean absolute error of only 1.6% for the weight fractions of the single urinary stone components. The largest error in weight fraction, 2.3%, occurred with hydroxylapatite, caused by the typical insufficient crystallinity. CONCLUSION: Crystallographic analysis of complex urinary stones with the aid of x-ray diffraction, in combination with a Rietveld structure refinement, is the method of first choice for qualitative and quantitative phase analysis. With this tool, significant changes in weight fractions for recurrent urinary stones can be precisely detected, with therapeutic consequences.

[Results of the evaluation of 85,337 urinary stone analyses]. / Ergebnisse der Harnsteinanalyse von uber 85337 Harnsteinen.

In this work 85337 urinary stones were analysed by X-ray diffraction in regard of their qualitative and quantitative composition. Urological practitioners and hospitals from all areas of the former FRG sent urinary stones to the Institute of Mineralogy in Bonn and to the Urology Department of the St Josef-Hospital in Troisdorf up to December 31st, 1994. The evaluations were carried out with special regard to the frequency of occurrence and to the quantity portions. The frequency of occurrence of one component describes the percentage of the urinary stones which contain this component. The quantity portion describes the average amount of one component in regard to all urinary stones which contain this component as well. The frequency of occurrence of whewellite was 75.77% and of wheddellite 46.41%. 34.25% of all calculi were monomineralic and 55.3% were bimineralic.