[Choosing wisely recommendations in intensive care medicine]. / Klug-entscheiden-Empfehlungen in der internistischen Intensivmedizin.

Intensive care medicine is an important and integral part of internal medicine. Modern intensive care medicine permits survival of many patients with severe and life-threatening internal diseases in acute situations. Decisive for therapeutic success is often not the application of complicated and expensive medical technologies, but rather the rapid diagnosis and identification of core issues, with immediate and competent initiation of standard treatment regimens. An adequately staffed, well-organized interprofessional team is of central importance. With the application of standard therapies, it has been increasingly demonstrated that "less is more", and that personalized treatment concepts are better than aggressive strategies with higher therapeutic goals. In accordance with the Choosing wisely recommendations of the American societies for intensive care medicine, the extended board of the Deutsche Gesellschaft für Internistische Intensivmedizin und Notfallmedizin (DGIIN) has formulated five positive and five negative recommendations reflecting these principles. The current paper is an updated version of the manuscript originally published in the Deutsches Ärzteblatt. When applying these recommendations, it is important to consider that intensive care patients are very complex; therefore, the applicability of these principles must be assessed on an individual basis and, where necessary, modified appropriately.

Micrometer-scale structure in shark vertebral centra.

The vertebral centra of sharks consist of cartilage, and many species' centra contain a bioapatite related to that in bone. Centra microarchitectures at the 0.5-50 µm scale do not appear to have been described previously. This study examines centrum microarchitecture in lamniform and carcharhiniform sharks with synchrotron microComputed Tomography (microCT), scanning electron microscopy and spectroscopy and light microscopy. The analysis centers on the blue shark (carcharhiniform) and shortfin mako (lamniform), species studied with all three modalities. Synchrotron microCT results from seven other species complete the report. The main centrum structures, the corpus calcareum and intermedialia, consist of fine, closely-spaced, mineralized trabeculae whose mean thicknesses and spacings range from 4.5 to 11.2 µm and 4.5 to 15.6 µm, respectively. A significant (p = 0.00001) positive linear relationship between and exists for multiple positions within one mako centrum. Carcharhiniform species' and exhibit an inverse linear relationship (p = 0.005) while in lamniforms these variables tend toward a positive relationship which does not reach statistical significance (p = 0.099). In all species, the trabeculae form an uninterrupted, interconnected network, and the unmineralized volumes are similarly interconnected. Small differences in mineralization level are observed in trabeculae. Centrum growth band pairs are found to consist of locally higher /lower mineral volume fraction. Within the intermedialia, radial canals and radial microrods were characterized, and compacted trabeculae are prominent in the mako intermedialia. The centra's mineralized central zones were non-trabecular and are also described. STATEMENT OF SIGNIFICANCE: This study's novel result is the demonstration that the mineralized cartilage of sharks' vertebral bodies (centra) consists of a fine 3D array of interconnected plates (trabeculae) and an interpenetrating network of unmineralized tissue. This microstructure is radically different from that in tesserae or in teeth, the other main mineralized shark tissues. Using volumetric synchrotron microComputed Tomography, numerical values of mean trabecular thickness and spacing and their relationship were measured for nine species. Scanning electron microscopy added a higher resolution view of the microstructures, and histology provided complementary information on cartilage and cells. The present results suggest centra microstructure helps accommodate the very large in vivo strains and may prevent damage accumulation during millions of cycles of swimming-induced loading.

Enamel hypoplasia in molars of sheep and goats, and its relationship to the pattern of tooth crown growth.

Enamel is the most highly mineralized and durable tissue of the mammalian body. As enamel does not undergo remodeling or repair, disturbances of enamel formation leave a permanent record in the tissue that can be used for life history reconstruction. This study reports light and scanning electron microscope findings on hypoplastic enamel defects, and on the chronology of crown growth in the molars of sheep and goats. A marked reduction of enamel extension rates in cervical compared with more cuspal crown portions of sheep and goat molars was recorded, with formation of the cervical 25% of the crown taking about the same time as that of the upper 75% of the crown. This explains the more frequent occurrence of enamel hypoplasia in cervical compared with upper and middle crown portions. Regarding the identification of hypoplastic enamel defects by external inspection, our results suggest a dependence on the type of defect and the associated presence of smaller or larger amounts of coronal cementum. Defects considered to reflect a slight to moderate impairment of secretory ameloblast function can normally be correctly diagnosed as they are not occluded by thick layers of cementum. In contrast, defects denoting a severe impairment of enamel matrix secretion can typically not be correctly identified because they are occluded by large amounts of cementum, so that neither depth nor extension of the defects can be assessed on external inspection. In these cases, microscopic analysis of tooth sections is required for a correct diagnosis of the hypoplastic enamel defects.

Antlers - Evolution, development, structure, composition, and biomechanics of an outstanding type of bone.

Antlers are bony appendages of deer that undergo periodic regeneration from the top of permanent outgrowths (the pedicles) of the frontal bones. Of the "less familiar" bone types whose study was advocated by John Currey to gain a better understanding of structure-function relationships of mineralized tissues and organs, antlers were of special interest to him. The present review summarizes our current knowledge about the evolution, development, structure, mineralization, and biomechanics of antlers and how their formation is affected by environmental factors like nutrition. Furthermore, the potential role of antlers as a model in bone biology and several fields of biomedicine as well as their use as a monitoring tool in environmental studies are discussed.

Insights from the inside: histological analysis of abnormal enamel microstructure associated with hypoplastic enamel defects in human teeth.

We studied the abnormalities in enamel microstructure associated with enamel hypoplasia in human teeth from the early medieval (5th-7th century AD) cemetery of Barbing, Germany, using light and scanning electron microscopy. The main aim of the study was to test the hypothesis that by analyzing the microstructure of fully formed enamel it is possible to reconstruct the reaction pattern of secretory ameloblasts to stress events leading to enamel hypoplasia. From the histological findings, a sequence of increasing impairment of secretory ameloblast function involving three thresholds was deduced. Surpassing of each of these thresholds is assumed to result in characteristic changes in enamel microstructure attributable to specific functional/morphological alterations of secretory ameloblasts. Based on our results we propose a model identifying the principal factors influencing the reaction of secretory ameloblasts to stress. The present study demonstrates that by including microscopic analysis in the study of enamel hypoplasia, it is possible to obtain a more complete picture of the formation of these developmental defects than is possible by inspection of crown surface features alone, and to draw more substantiated conclusions about the possible nature of developmental defects of enamel.

Deposition of cellular cementum onto hypoplastic enamel of fluorotic teeth in wild boars (Sus scrofa L.).

The nature of deposits present in hypoplastic defects of fluorotic enamel of wild boar teeth was studied by light microscopy and scanning electron microscopy. The fluorotic enamel showed different developmental abnormalities, denoting a severe disturbance of ameloblast function during the secretory stage of amelogenesis. These abnormalities included the occurrence of grossly accentuated incremental lines with associated zones of aprismatic enamel and the presence of different forms of hypoplastic defects. Two types of deposits were present on the hypoplastic enamel: cellular cementum and posteruptively acquired, presumably partially mineralized dental plaque. Coronal cementum is not normally formed in pig teeth. Presence of this tissue in fluorotic teeth of wild boars is seen as indicative of a premature disintegration of the enamel epithelium prior to the completion of amelogenesis. This was supposed to have resulted in a contact of mesenchymal cells of the dental follicle with the surface of the immature enamel and, in consequence, in a differentiation of these cells into cementoblasts. To our knowledge, this is the first study reporting the formation of coronal cementum as part of the spectrum of pathological changes in fluorotic teeth in a species whose tooth crowns are normally free of cementum.

Is cytokine removal by continuous hemofiltration feasible?

Patients who are critically ill with acute renal failure and sepsis have extremely high mortality rates. While it seems reasonable that eliminating the inflammatory mediators (such as cytokines, chemokines, tumor necrosis factor-alpha, etc.) by continuous renal replacement therapy (CRRT) would be effective, studies show that only insubstantial numbers of these mediators are removed in comparison with endogenous clearance. Mass removal seems only to be effective when highly permeable membranes (sieving coefficient of approximately 1.0) are used, there is a filtrate volume greater than 2 liters/hour, and when the half-life of the substance to be eliminated is greater than 60 minutes. Removal of cytokines by membrane adsorption is another possibility. However, because the membrane surfaces are saturated after a few hours, frequent filter changes are necessary for them to generate effective adsorption of these mediators. Despite filter changes, only a brief and transient drop in the TNF plasma level has been observed. Controlled clinical trials are needed to determine whether or not CRRT actually has a beneficial effect on the systemic inflammatory response syndrome (SIRS).

Lactate- or bicarbonate-buffered solutions in continuous extracorporeal renal replacement therapies.

BACKGROUND: Continuous renal replacement therapies (CRRTs) are well accepted for critically ill patients with acute renal failure (ARF). Today, daily fluid exchange in CRRT reaches 30 to 40 liter and more. Therefore, the composition of the substitution/dialysate fluid, often primarily developed either for intermittent treatment or for peritoneal dialysis, becomes more relevant. Lactate (30 to 45 mmol/liter) is frequently used as the buffer because of the high stability of this substance. However, lactate is thought to have negative effects on metabolic and hemodynamic parameters. METHODS: Published data for different substitution fluids are presented with respect to acidosis and lactate concentration, uremia, and hemodynamic and metabolic alterations. RESULTS: Only a few studies compare substitution fluids with different buffers. Uremia and acidosis (pH, base excess) were sufficiently controlled during CRRT with an exchange volume of in average 30 liters using either buffer. If patients with severe liver failure and lactic acidosis were excluded, no difference in hemodynamic and metabolic parameters between the solutions occurred. The plasma lactate concentration was elevated during lactate use in some cases, but lactate levels remained within normal limits in patients without liver impairment. The bicarbonate concentration in the solutions should exceed 35 to 40 mmol/liter, as in some cases the buffer capacity of the solutions was inadequate. In patients with severe liver failure or lactic acidosis, solutions with lactate buffer were shown not to be indicated. CONCLUSION: In patients with reduced lactate metabolism, for example, concomitant severe liver failure, after liver transplantation or in lactic acidosis, bicarbonate-buffered solutions should be used. In nearly all other cases of critically ill patients with ARF, lactate-buffered solutions may be used as well as bicarbonate solutions.

Hirudin elimination by hemofiltration: a comparative in vitro study of different membranes.

BACKGROUND: Recombinant hirudin (r-hirudin) is a highly specific and selective thrombin inhibitor. Since 1997, it has been approved for the treatment of heparin-induced thrombocytopenia (HIT type II). Renal function impairment drastically prolongs the elimination half-life time. In cases of bleeding or overdosage, there is currently no antidote available. Hemofiltration has been reported to be useful in r-hirudin elimination. In this study, we determined sieving coefficients (SCs) and drug clearances for two different hemofilters currently used in clinical medicine and intensive care. METHODS: We developed an in vitro postdilution hemofiltration model using 500 ml heparinized (2 IU unfractionated heparin/ml) fresh human blood and bicarbonate substitution fluid. The investigated membranes were high-flux polysulfone F50 (1.0 m2, Fresenius) and AN69 Nephral 200 (1.05 m2, Hospal Cobe). After equilibration, a bolus of Lepirudin was injected into the postfilter port to achieve a r-hirudin blood level of approximately 15 microg/ml. Serial blood and ultrafiltrate samples were taken for the determination of hirudin levels (chromogenic assay) and control parameters. SC and clearances were calculated according to standard formulae. RESULTS: The observed SCs and clearances differed significantly between F50 and Nephral 200 (0.60+/-0.17 and 21.0+/-5.9 ml/min, respectively, vs. 0.44+/-0.09 and 15.5+/-3.0 ml/min, respectively; P = 0.001). The determination of prothrombin fragments showed no coagulation activation during the experiments. The hematocrit values remained stable. CONCLUSIONS: Our data show that r-hirudin can be eliminated by hemofiltration. The elimination obviously depends on the membrane material with high-flux polysulfone being more effective than AN69. These findings may be important in cases of overdosage and for r-hirudin dosage guidelines in continuous hemofiltration.

Influence of hematocrit on hemostasis in continuous venovenous hemofiltration during acute renal failure.

BACKGROUND: Hematocrit plays a major role in primary hemostasis by influencing blood viscosity and platelet adhesion. During continuous venovenous hemofiltration (CVVH), it is suspected that an increased hematocrit is accompanied by an activation of hemostasis and frequently leads to thromboses in the extracorporeal system. In order to examine this hypothesis, we studied the influence of hematocrit on hemostasis during CVVH. METHODS: Fourteen patients (8 men and 6 women, mean age 65+/-10 years) with acute renal failure undergoing CVVH were prospectively enrolled. Polysulfone hemofilters (AV 600; Fresenius, Oberursel, Germany) were used in all of the patients; blood flow rates were adjusted to 120 ml/min. No blood products and coagulation-related medication, except unfractionated heparin, were applied. Study exclusion criteria included a history of thromboembolism and artificial heart valves. Hemostasis activation markers (fibrinopeptide A, thrombin-antithrombin III complex, beta-thromboglobulin, platelet retention) and hematocrit values were determined before and at three-day intervals during the course of CVVH treatment. RESULTS: The mean hematocrit value (mean +/- SEM) was 29+/-1% (range, 22 to 35%). Patients with hematocrit values of less than 30% (N = 7) were compared with patients with higher hematocrit values (>30%, N = 7). The patients with a lower hematocrit (<30%) showed a stronger activation of hemostasis during CVVH when compared with those with a higher hematocrit (>30%), as indicated by a tendency toward higher values for fibrinopeptide A (25+/-8 vs. 14+/-5 ng/ml, P = 0.35), thrombin-antithrombin III complex (15+/-4 vs. 10+/-2 ng/ml, P = 0.66), and a higher beta-thromboglobulin/creatinine ratio (0.62+/-0.17 vs. 0.48+/-0.12, P = 0.8). CONCLUSION: Contrary to our hypothesis, hematocrit values of more than 30% are not accompanied by an increased hemostasis activation during CVVH. Concerning hemostasis activation, hematocrit values between 30 and 35% may be suitable for patients on CVVH.

A scanning electron microscopic study on the distribution of peritubular dentine in cheek teeth of Cervidae and Suidae (Mammalia, Artiodactyla).

Distribution of peritubular dentine was studied in cheek teeth of fallow deer (Dama dama), roe deer (Capreolus capreolus) and wild boar (Sus scrofa). In the two cervid species, especially intense peritubular dentine formation was found in the outer regions of mid and cuspal coronal dentine. In these areas a marked asymmetry occurred, peritubular dentine being predominantly secreted onto the side of the dentinal tubule walls nearest to the dentinoenamel junction. Intensity and asymmetry of peritubular dentine formation decreased cervically. In root dentine, the walls of the dentinal tubules were covered with only a thin peritubular dentine layer of even thickness. Here, in contrast to peripheral coronal dentine, the volume of intertubular dentine far exceeded that of peritubular dentine. In porcine coronal dentine, PTD asymmetry, being of lesser extent than in cervids, was observed only in peripheral areas of cuspal and flank regions of the cheek teeth. Because peritubular is more highly mineralized than intertubular dentine, the relative volume of dentine made up from the two components has an important influence on dentinal wear resistance. The significance of variations in volume and distribution of peritubular dentine between different dentinal regions for achieving and maintaining a functional occlusal surface is shown for cervid cheek teeth. Our results suggest that dentinal structure (in addition to enamel structure) should be taken more into consideration when discussing occlusal surface morphology in herbi- and omnivores from a functional point of view.

Fluoride-induced alterations of enamel structure: an experimental study in the miniature pig.

We studied the structural changes in the enamel of mandibular third molars of miniature pigs administered a daily oral dose of 2 mg NaF (approximately 0.9 mg of fluoride) per kg body weight (added to the feed) for 1 year. The treatment period covered most of the secretory stage and the entire post-secretory stage of amelogenesis of the M(3). The enamel of the molars from the fluoride-fed pigs appeared opaque and chalky, and the erupted portions were stained brown. The underlying histopathological change was a pronounced subsurface hypomineralization of the enamel beneath a thin surface rim of higher mineral content. This enamel hypomineralization was attributed to a fluoride-induced impairment of the process of enamel maturation. The most conspicuous finding in the fluorotic enamel was the presence of numerous pit-type hypoplastic defects, denoting a marked fluoride-induced disturbance also of the secretory stage of amelogenesis. Microradiography and scanning electron microscopy revealed an enhanced incremental pattern in the outer enamel of the fluorotic molars. Typically, the bottom of larger hypoplastic defects was underlain by a broad, grossly accentuated incremental line. Occurrence of larger hypoplasias was further associated with the presence of aprismatic enamel, the formation of which was attributed to a loss of the prism-forming (distal) portion of the Tomes' processes of secretory ameloblasts. The findings in the miniature pigs closely parallel earlier observations on fluorotic enamel of free-ranging deer and wild boar from fluoride-polluted areas.

Immunoreactive parathyroid hormone after volume change in normo- and hypotensive hemodialysis patients.

The effects of reduced blood volume during hemodialysis on circulating immunoreactive parathyroid hormone (PTH) were determined in relation to changes in blood pressure and heart rate in normo- and hypotensive patients with end stage renal failure. During dialysis the plasma concentration of PTH did not change in normotensives, while PTH increased significantly in patients with a fall in blood pressure during a 25% reduction in effective intravascular volume. The blood volume was measured continuously during hemodialysis using the authors' hemoglobin measurement system. The decrease in blood volume in both groups was comparable. The results suggest that secretion of PTH during hemodialysis may play a role in hemodynamic instability during hemodialysis.

Occurrence of a postpermanent mandibular fourth premolar in a moose bull (Alces alces L.).

By a number of diagnostic criteria a supplemental premolar in the right hemimandible of a 6-yr-old moose bull from Bielorussia was identified as a postpermanent fourth premolar. Its development, which must have started at least 3 yr after the permanent fourth premolar had reached its functional position, resulted in rotation of the P4 by 80 degrees, as well as extensive resorption on both root and crown.

Fluoride-induced developmental changes in enamel and dentine of European roe deer (Capreolus capreolus L.) as a result of environmental pollution.

Using macroscopic, microradiographic and scanning electron-microscopic methods, the effects of increased fluoride exposure on enamel and dentine formation were studied in fluorosed mandibular premolars and molars of roe deer from the heavily industrialized Ruhr area, Germany. Macroscopically, fluorosed teeth were characterized by opaque and stained enamel and in more severe cases also by enamel surface lesions, reduction or loss of enamel ridges on their occlusal surfaces and increased wear. Microradiographically, fluorosed enamel exhibited different degrees of subsurface hypomineralization, in part apparently indicating a fluoride effect during enamel maturation. In some specimens, a pronounced but varying enhancement of the pattern of Retzius lines was observed throughout the enamel, denoting strongly intermittent fluoride exposure during enamel matrix secretion. This variation in exposure was also reflected histologically in dentine, by bands of interglobular dentine and marked accentuation of incremental lines. Microradiography of sections through enamel surface hypoplastic lesions showed the enamel forming the bottom and partly also the walls of the lesions to be highly mineralized. Scanning electron microscopy showed that the outer enamel along the more pronounced hypoplastic lesions consisted of stacked, thin layers of 'aprismatic' enamel, indicating that the ameloblasts in these areas had lost the distal (rod-forming) regions of their Tomes' processes. These observations demonstrate that the origin of enamel hypoplasias in deer clearly differs from that in rodents, where fluoride induces the formation of subameloblastic cysts. The differences in the degree of fluorotic alteration between the teeth of a single tooth row could be related to the developmental sequence of the dentition in roe deer. The roe deer is thus considered to be a very sensitive and useful bioindicator of environmental pollution by fluorides.

Reconstruction of a decline of ambient lead levels in the Ruhr area (Germany) by studying lead concentrations in antlers of roe deer (Capreolus capreolus).

We determined lead concentrations in antlers (n = 132) of roe bucks > or = 2 years of age, killed between 1951 and 1999 in the northern Ruhr area, Germany. The lead content of the antlers ranged between 0.6 and 19.0 mg/kg dry weight of bone, and overall markedly declined over the study period. As a consequence, mean lead levels in younger samples were always significantly (P<0.001) lower than those in older ones (for the periods: 1951-1969, 1970-1979, 1980-1989 and 1990-1999). Annual mean antler lead concentrations were positively correlated (r(s) = 0.74, P<0.001) with annual mean lead concentrations in airborne particulate matter of the Rhine-Ruhr area during the period 1974-1999. The findings of the present study underscore that roe deer antlers are well suited for a monitoring of temporal trends in environmental lead levels in a cost-effective way.

Monitoring regional fluoride pollution in the Saxonian Ore mountains (Germany) using the biomarker dental fluorosis in roe deer (Capreolus capreolus L.).

The spatial variation of fluoride contamination in the Saxonion part of the Ore mountains (Federal state of Saxony, Germany) was assessed by analysing the prevalence and severity of dental fluorosis in wild male roe deer aged 2 years or more (n = 794) from this region. The study area is exposed to increased atmospheric deposition of fluorides, originating from emission sources in the North-Bohemian brown coal belt. The severity of dental fluorosis in the permanent premolars and molars of one hemimandible per animal was assessed based on a scoring system and a dental lesion index of fluorosis (DLI) assigned to each specimen. On the basis of the mean DLI calculated for the roe deer originating from a certain municipal district, the respective deer sample was assigned to one of seven fluorosis categories, and a map showing the distribution of these categories was produced. Highest fluorosis categories were recorded for roe deer samples from the central and eastern parts of the study area that directly bordered on, or were located near to, the Czech-German border. A close spatial relationship between the main fluoride emission sources in North-Bohemia and the regions with the highest prevalence and severity of dental fluorosis in roe deer was discernible. The observed regional variation of fluoride pollution is in accordance with the results of other studies directly measuring fluoride deposition into the study area or fluoride levels in vegetation. A main advantage of the method used in this study over other ways of recording fluoride contamination of wildlife habitats is that it uses an established and continuously operated system of specimen collection, thereby enabling efficient monitoring with high spatial and temporal resolution at very low cost. Moreover, a clearly recognisable and relevant biological effect is measured which occurs in a dose-dependent manner over a range of environmentally relevant concentrations.

Mandibular bone fluoride levels and occurrence of fluoride induced dental lesions in populations of wild red deer (Cervus elaphus) from Central Europe.

Mandibular bone fluoride concentrations as well as frequency and intensity of fluoride-induced dental lesions were studied in four red deer populations from Czechia and Germany exposed to different levels of environmental fluoride. The degree of fluorosis in the permanent cheek teeth was recorded by a scoring system and the individual mandibles assigned to one of three categories (unfluorosed, slightly to moderately fluorosed, and markedly to severely fluorosed) on the basis of the tooth scores. An increase in the frequency and severity of dental fluorosis was positively associated with an increase in bone fluoride level, which itself was significantly different between the four samples. In all samples, the rate of bone fluoride accumulation was higher in younger than in older deer. The results of this study show that frequency and intensity of dental fluorosis can be used as valid indicators of increased fluoride exposure of deer populations, and thus as a quick, easy, economic and reliable means of monitoring fluoride pollution in areas inhabited by wild deer.

Is continuous haemofiltration superior to intermittent dialysis and haemofiltration treatment?

1. Mortality in cases of acute renal failure has increased from roughly 30% to roughly 70% in recent decades. 2. The rise paralleled the creation of intensive care units. In such units, more seriously ill patients reach the stage of acute renal failure. Before the advent of intensive care units, these patients died before acute renal failure could occur. 3. From a theoretical viewpoint, continuous haemofiltration (CH) has substantial advantages as opposed to intermittent dialysis and haemofiltration treatment. 4. No clinical proof of the superiority of continuous haemofiltration to the intermittent techniques has yet been provided. 5. In our own patient group, total mortality for acute renal failure patients decreased following adoption of continuous haemofiltration. During a selected period of use of continuous haemofiltration for patients with an unfavourable prognosis, however, the mortality with continuous haemofiltration was higher than that with the intermittent methods.

Fluoride concentrations in antler bone of roe deer (Capreolus capreolus) indicate decreasing fluoride pollution in an industrialized area of western Germany.

In order to reconstruct temporal changes in ambient fluoride levels in the industrialized Ruhr area (western Germany), we analyzed the bone fluoride content of 167 antlers of roe deer (Capreolus capreolus) killed between 1951 and 1999 in the northern part of this region. Individual values ranged between 110 and 8,178 mg F-/kg ash, and there was an overall marked decrease over the sampling period. Average bone fluoride concentrations in antlers from the periods 1980 through 1989 (geometric mean [95% confidence interval]: 1,490 [1,193-1,861] mg/kg ash) and 1990 through 1999 (753 [644-882] mg/kg ash) differed significantly (p < 0.001) and were both significantly (p < 0.001) lower than those from the periods 1951 through 1969 (3,720 [3,227-4,288] mg/kg ash) and 1970 through 1979 (2,573 [2,203-3,006] mg/kg ash). The findings are seen as indicative of a progressively reduced atmospheric fluoride deposition into the study area, caused by effective emission-control measures in Germany and neighboring countries. Because antlers are replaced annually, grow during a fixed period of some months, and are regularly collected and kept as trophies, they are well suited as monitoring units for analyzing temporal trends in environmental pollution by fluoride and other bone-seeking pollutants.