Vitellogenin synthesis in primary cultures of fish liver cells as endpoint for in vitro screening of the (anti)estrogenic activity of chemical substances

Concern over possible adverse effects of endocrine-disrupting compounds on fish has caused the development of appropriate testing methods. In vitro screening assays may provide initial information on endocrine activities of a test compound and thereby may direct and optimize subsequent testing. Induction of vitellogenin (VTG) is used as a biomarker of exposure of fish to estrogen-active substances. Since VTG induction can be measured not only in vivo but also in fish hepatocytes in vitro, the use of VTG induction response in isolated fish liver cells has been suggested as in vitro screen for identifying estrogenic-active substances. The main advantages of the hepatocyte VTG assay are considered its ability to detect effects of estrogenic metabolites, since hepatocytes in vitro remain metabolically competent, and its ability to detect both estrogenic and anti-estrogenic effects. In this article, we critically review the current knowledge on the VTG response of cultured fish hepatocytes to (anti)estrogenic substances. In particular, we discuss the sensitivity, specificity, and variability of the VTG hepatocyte assay. In addition, we review the available data on culture factors influencing basal and induced VTG production, the response to natural and synthetic estrogens as well as to xenoestrogens, the detection of indirect estrogens, and the sources of assay variability. The VTG induction in cultured fish hepatocytes is clearly influenced by culture conditions (medium composition, temperature, etc.) and culture system (hepatocyte monolayers, aggregates, liver slices, etc.). The currently available database on estrogen-mediated VTG induction in cultured teleost hepatocytes is too small to support conclusive statements on whether there exist systematic differences of the VTG response between in vitro culture systems, VTG analytical methods or fish species. The VTG hepatocyte assay detects sensitively natural and synthetic estrogens, whereas the response to xenoestrogens appears to be more variable. The detection of weak estrogens can be critical due to the overshadow with cytotoxic concentrations. Moreover, the VTG hepatocyte assay is able to detect antiestrogens as well as indirect estrogens, i.e substances which require metabolic activation to induce an estrogenic response. Nevertheless, more chemicals need to be analysed to corroborate this statement. It will be necessary to establish standardized protocols to minimize assay variability, and to develop a set of pass-fail criteria as well as cut-offs for designating positive and negative responses.

Is hypoxia training good for muscles and exercise performance?

Altitude training has become very popular among athletes as a means to further increase exercise performance at sea level or to acclimatize to competition at altitude. Several approaches have evolved during the last few decades, with "live high-train low" and "live low-train high" being the most popular. This review focuses on functional, muscular, and practical aspects derived from extensive research on the "live low-train high" approach. According to this, subjects train in hypoxia but remain under normoxia for the rest of the time. It has been reasoned that exercising in hypoxia could increase the training stimulus. Hypoxia training studies published in the past have varied considerably in altitude (2300-5700 m) and training duration (10 days to 8 weeks) and the fitness of the subjects. The evidence from muscle structural, biochemical, and molecular findings point to a specific role of hypoxia in endurance training. However, based on the available performance capacity data such as maximal oxygen uptake (Vo(2)max) and (maximal) power output, hypoxia as a supplement to training is not consistently found to be advantageous for performance at sea level. Stronger evidence exists for benefits of hypoxic training on performance at altitude. "Live low-train high" may thus be considered when altitude acclimatization is not an option. In addition, the complex pattern of gene expression adaptations induced by supplemental training in hypoxia, but not normoxia, suggest that muscle tissue specifically responds to hypoxia. Whether and to what degree these gene expression changes translate into significant changes in protein concentrations that are ultimately responsible for observable structural or functional phenotypes remains open. It is conceivable that the global functional markers such as Vo(2)max and (maximal) power output are too coarse to detect more subtle changes that might still be functionally relevant, at least to high-level athletes.

Extremely Violent Societies: Mass Violence in the Twentieth Century World

In this groundbreaking book Christian Gerlach traces the social roots of the extraordinary processes of human destruction involved in mass violence throughout the twentieth century. He argues that terms such as 'genocide' and 'ethnic cleansing' are too narrow to explain the diverse motives and interests that cause violence to spread in varying forms and intensities. From killings and expulsions to enforced hunger, collective rape, strategic bombing, forced labour and imprisonment he explores what happened before, during, and after periods of widespread bloodshed in countries such as Armenia, Indonesia, Bangladesh, Nazi-occupied Greece and in anti-guerilla wars worldwide in order to highlight the crucial role of socio-economic pressures in the generation of group conflicts. By focussing on why so many different people participated in or supported mass violence, and why different groups were victimized, he offers us a new way of understanding one of the most disturbing phenomena of our times.

Drug hypersensitivity: flare-up reactions, cross-reactivity and multiple drug hypersensitivity

In drug hypersensitivity, change of drug treatment and continuation with a new drug may result in reappearance of drug hypersensitivity symptoms. This is not uncommon in patients with chronic infections requiring continued and long-lasting antibiotic treatments. For the clinician, the question arises whether these symptoms are due to cross-reactivity, are due to a new sensitization or are a reflection of a multiple drug hypersensitivity syndrome. Based on the p-i concept (pharmacological interaction with immune receptors), we propose that the efficient stimulation of T cells by a drug is the sum of drug-T-cell receptor affinity and readiness of the T cell to react, and therefore not constant. It heavily depends on the state of underlying immune activation. Consequently, drug hypersensitivity diseases, which go along with massive immune stimulations and often high serum cytokine values, are themselves risk factors for further drug hypersensitivity. The immune stimulation during drug hypersensitivity may, similar to generalized virus infections, lower the threshold of T-cell reactivity to drugs and cause rapid appearance of drug hypersensitivity symptoms to the second drug. We call the second hypersensitivity reaction a "flare-up" reaction; this is clinically important, as in most cases the second drug may be tolerated again, if the cofactors are missing. Moreover, the second treatment is often too short to cause a relevant sensitization.

Effect of Population Heterogenization on the Reproducibility of Mouse Behavior: A Multi-Laboratory Study

In animal experiments, animals, husbandry and test procedures are traditionally standardized to maximize test sensitivity and minimize animal use, assuming that this will also guarantee reproducibility. However, by reducing within-experiment variation, standardization may limit inference to the specific experimental conditions. Indeed, we have recently shown in mice that standardization may generate spurious results in behavioral tests, accounting for poor reproducibility, and that this can be avoided by population heterogenization through systematic variation of experimental conditions. Here, we examined whether a simple form of heterogenization effectively improves reproducibility of test results in a multi-laboratory situation. Each of six laboratories independently ordered 64 female mice of two inbred strains (C57BL/6NCrl, DBA/2NCrl) and examined them for strain differences in five commonly used behavioral tests under two different experimental designs. In the standardized design, experimental conditions were standardized as much as possible in each laboratory, while they were systematically varied with respect to the animals' test age and cage enrichment in the heterogenized design. Although heterogenization tended to improve reproducibility by increasing within-experiment variation relative to between-experiment variation, the effect was too weak to account for the large variation between laboratories. However, our findings confirm the potential of systematic heterogenization for improving reproducibility of animal experiments and highlight the need for effective and practicable heterogenization strategies.

[Treatment of nonalcoholic steatohepatitis]

NASH associates steatosis with parenchymal inflammation and signs of hepatocellular injuy and even apoptosis. This leads in a minority of patients to fibrosis and in the long term to cirrhosis. NASH regularly occurs in a metabolic context characterized by insulin resistance. Several drugs have been tested in randomized controlled studies. Glitazones improve insulin resistance and also NASH, but are associated with side effects particularly unwelcome in NASH patients. Ursodesoxycholic acid, an hydrophilic biliary acid with hepatoprotective properties, does not improve the histological lesions of NASH. Vitamin E is the only compound which showed so far a positive effect without relevant side effects. However, it is too early to recommend its long-term use in this indication. Finally, the best treatment is not with drugs, but relies on behavioural changes: NASH patients should regularly exercise!

Ocean acidification limits temperature-induced poleward expansion of coral habitats around Japan

Using results from four coupled global carbon cycle-climate models combined with in situ observations, we estimate the effects of future global warming and ocean acidification on potential habitats for tropical/subtropical and temperate coral communities in the seas around Japan. The suitability of coral habitats is classified on the basis of the currently observed regional ranges for temperature and saturation states with regard to aragonite (Ωarag). We find that, under the "business as usual" SRES A2 scenario, coral habitats are projected to expand northward by several hundred kilometers by the end of this century. At the same time, coral habitats are projected to become sandwiched between regions where the frequency of coral bleaching will increase, and regions where Ωarag will become too low to support sufficiently high calcification rates. As a result, the habitat suitable for tropical/subtropical corals around Japan may be reduced by half by the 2020s to 2030s, and is projected to disappear by the 2030s to 2040s. The habitat suitable for the temperate coral communities is also projected to decrease, although at a less pronounced rate, due to the higher tolerance of temperate corals for low Ωarag. Our study has two important caveats: first, it does not consider the potential adaptation of the coral communities, which would permit them to colonize habitats that are outside their current range. Second, it also does not consider whether or not coral communities can migrate quickly enough to actually occupy newly emerging habitats. As such, our results serve as a baseline for the assessment of the future evolution of coral habitats, but the consideration of important biological and ecological factors and feedbacks will be required to make more accurate projections.

The origin of the European Medieval Warm Period"

Proxy records and results of a three dimensional climate model show that European summer temperatures roughly a millennium ago were comparable to those of the last 25 years of the 20th century, supporting the existence of a summer "Medieval Warm Period" in Europe. Those two relatively mild periods were separated by a rather cold era, often referred to as the "Little Ice Age". Our modelling results suggest that the warm summer conditions during the early second millennium compared to the climate background state of the 13th–18th century are due to a large extent to the long term cooling induced by changes in land-use in Europe. During the last 200 years, the effect of increasing greenhouse gas concentrations, which was partly levelled off by that of sulphate aerosols, has dominated the climate history over Europe in summer. This induces a clear warming during the last 200 years, allowing summer temperature during the last 25 years to reach back the values simulated for the early second millennium. Volcanic and solar forcing plays a weaker role in this comparison between the last 25 years of the 20th century and the early second millennium. Our hypothesis appears consistent with proxy records but modelling results have to be weighted against the existing uncertainties in the external forcing factors, in particular related to land-use changes, and against the uncertainty of the regional climate sensitivity. Evidence for winter is more equivocal than for summer. The forced response in the model displays a clear temperature maximum at the end of the 20th century. However, the uncertainties are too large to state that this period is the warmest of the past millennium in Europe during winter.

Pharmacological interaction of drugs with immune receptors: the p-i concept

Drug-induced hypersensitivity reactions have been explained by the hapten concept, according to which a small chemical compound is too small to be recognized by the immune system. Only after covalently binding to an endogenous protein the immune system reacts to this so called hapten-carrier complex, as the larger molecule (protein) is modified, and thus immunogenic for B and T cells. Consequently, a B and T cell immune response might develop to the drug with very heterogeneous clinical manifestations. In recent years, however, evidence has become stronger that not all drugs need to bind covalently to the MHC-peptide complex in order to trigger an immune response. Rather, some drugs may bind directly and reversibly to immune receptors like the major histocompatibility complex (MHC) or the T cell receptor (TCR), thereby stimulating the cells similar to a pharmacological activation of other receptors. This concept has been termed pharmacological interaction with immune receptors the (p-i) concept. While the exact mechanism is still a matter of debate, non-covalent drug presentation clearly leads to the activation of drug-specific T cells as documented for various drugs (lidocaine, sulfamethoxazole (SMX), lamotrigine, carbamazepine, p-phenylendiamine, etc.). In some patients with drug hypersensitivity, such a response may occur within hours even upon the first exposure to the drug. Thus, the reaction to the drug may not be due to a classical, primary response, but rather be mediated by stimulating existing, pre-activated, peptide-specific T cells that are cross specific for the drug. In this way, certain drugs may circumvent the checkpoints for immune activation imposed by the classical antigen processing and presentation mechanisms, which may help to explain the peculiar nature of many drug hypersensitivity reactions.

Feline caries in two cats from a 13th century archeological excavation

Mandibles of two cats containing carious lesions were discovered among the previously published findings of feline dental resorptive lesions from materials examined at an archaeological museum. These lesions were too small to be noted on radiographs, and consisted of two inconspicuous enamel lesions in a mandibular left first molar tooth (309), a clinically visible white spot area containing an enamel lesion in a mandibular left fourth premolar tooth (308), and a root surface caries in the 308 of a different specimen. Histologic examination using special stains and polarized light revealed both initial and early initial stage enamel caries, as well as root surface caries. Knoop hardness measurements confirmed these findings, considered the first documented cases of feline caries.

Frequency of Malaria and Glucose-6-phosphate Dehydrogenase Deficiency in Tajikistan

Background During the Soviet era, malaria was close to eradication in Tajikistan. Since the early 1990s, the disease has been on the rise and has become endemic in large areas of southern and western Tajikistan. The standard national treatment for Plasmodium vivax is based on primaquine. This entails the risk of severe haemolysis for patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency. Seasonal and geographical distribution patterns as well as G6PD deficiency frequency were analysed with a view to improve understanding of the current malaria situation in Tajikistan. Methods Spatial and seasonal distribution was analysed, applying a risk model that included key environmental factors such as temperature and the availability of mosquito breeding sites. The frequency of G6PD deficiency was studied at the health service level, including a cross-sectional sample of 382 adult men. Results Analysis revealed high rates of malaria transmission in most districts of the southern province of Khatlon, as well as in some zones in the northern province of Sughd. Three categories of risk areas were identified: (i) zones at relatively high malaria risk with high current incidence rates, where malaria control and prevention measures should be taken at all stages of the transmission cycle; (ii) zones at relatively high malaria risk with low current incidence rates, where malaria prevention measures are recommended; and (iii) zones at intermediate or low malaria risk with low current incidence rates where no particular measures appear necessary. The average prevalence of G6PD deficiency was 2.1% with apparent differences between ethnic groups and geographical regions. Conclusion The study clearly indicates that malaria is a serious health issue in specific regions of Tajikistan. Transmission is mainly determined by temperature. Consequently, locations at lower altitude are more malaria-prone. G6PD deficiency frequency is too moderate to require fundamental changes in standard national treatment of cases of P. vivax.

Sample sizes of studies on diagnostic accuracy: literature survey

OBJECTIVES: To determine sample sizes in studies on diagnostic accuracy and the proportion of studies that report calculations of sample size. DESIGN: Literature survey. DATA SOURCES: All issues of eight leading journals published in 2002. METHODS: Sample sizes, number of subgroup analyses, and how often studies reported calculations of sample size were extracted. RESULTS: 43 of 8999 articles were non-screening studies on diagnostic accuracy. The median sample size was 118 (interquartile range 71-350) and the median prevalence of the target condition was 43% (27-61%). The median number of patients with the target condition--needed to calculate a test's sensitivity--was 49 (28-91). The median number of patients without the target condition--needed to determine a test's specificity--was 76 (27-209). Two of the 43 studies (5%) reported a priori calculations of sample size. Twenty articles (47%) reported results for patient subgroups. The number of subgroups ranged from two to 19 (median four). No studies reported that sample size was calculated on the basis of preplanned analyses of subgroups. CONCLUSION: Few studies on diagnostic accuracy report considerations of sample size. The number of participants in most studies on diagnostic accuracy is probably too small to analyse variability of measures of accuracy across patient subgroups.

Global control of sexually transmitted infections

Sexually transmitted infections other than HIV are important global health issues. They have, however, been neglected as a public-health priority and control efforts continue to fail. Sexually transmitted infections, by their nature, affect individuals, who are part of partnerships and larger sexual networks, and in turn populations. We propose a framework of individual, partnership, and population levels for examining the effects of sexually transmitted infections and interventions to control them. At the individual level we have a range of effective diagnostic tests, treatments, and vaccines. These options are unavailable or inaccessible in many resource-poor settings, where syndromic management remains the core intervention for individual case management. At the partnership level, partner notification and antenatal syphilis screening have the potential to prevent infection and re-infection. Interventions delivered to whole populations, or groups in whom the risks of infection and onward transmission are very high, have the greatest potential effect. Improvements to the infrastructure of treatment services can reduce the incidence of syphilis and gonorrhoea or urethritis. Strong evidence for the effectiveness of most other interventions on population-level outcomes is, however, scarce. Effective action requires a multifaceted approach including better basic epidemiological and surveillance data, high quality evidence about effectiveness of individual interventions and programmes, better methods to get effective interventions onto the policy agenda, and better advocacy and more commitment to get them implemented properly. We must not allow stigma, prejudice, and moral opposition to obstruct the goals of infectious disease control.

Subsecond fluorine-19 MRI of the lung

Minimal scan times in rapid fluorine-19 MRI using sulfur hexafluoride (SF6) have been on the order of 10 s. Because of the very short T1 relaxation time of SF6 (T1 = 1.65 ms), high receiver bandwidths are necessary to allow for a high number of excitations. Since high bandwidths cause high levels of electronic noise, SNR per acquisition has been too low to further reduce scan time. The purpose of this study was to investigate whether scan times could be reduced using hexafluoroethane (C2F6), a gas with a longer T1 (T1 = 7.9 ms) at a relatively low bandwidth of 488 Hz/pixel. Gradient-echo images were acquired during and after completion of the wash-in of a 70% C2F6- 30% O2 mixture. Peak SNR values of 16 and 7.9 were observed for coronal projection images acquired within 2 s and 260 ms, respectively. These results demonstrate that subsecond imaging is feasible using C2F6.

[Femoroacetabular impingement: trigger for the development of coxarthrosis]

Femoroacetabular impingement (FAI) is frequent; the estimated prevalence ranges between 10 and 15%. Our 10-years experience strongly suggests that FAI leads to osteoarthritis. Isolated acetabular or femoral abnormalities are rare, even though in women acetabular and in men femoral abnormalities predominate. Normal radiographs do not exclude the presence of FAI. Symptoms are related to the degree of deformity and occur earlier in the presence of activities requiring high levels of motion. The majority of patients with FAI are under the age of 40 years.In contrast to impingement in total hip replacement, the natural hip is under much higher constraint, not allowing to escape from impingement-induced shear forces by subluxation or complete dislocation. FAI-induced shear forces due to an aspherical femoral head/neck (cam type) are therefore high, causing outside-in damage with cleavage lesions of the acetabular cartilage by forced flexion and internal rotation. The cartilage of the femoral head remains initially intact, which cannot be explained by the classic concept of osteoarthritis. After the femoral head has migrated into the acetabular cartilage defect, vertical forces contribute to the further course of osteoarthritis. Tears between the labrum and cartilage, as seen by MRI, are not avulsions of the labrum from the cartilage but rather outside-in avulsions of the cartilage from the labrum. In acetabular overcoverage (pincer type) the labrum is the first structure to fail and acetabular cartilage damage develops thereafter.The treatment of FAI in patients under the age of 40 years is aimed at joint preservation. The clinical result is worse in the presence of significant cartilage damage. Therefore, early appreciation of FAI and timely therapeutic intervention as well as professional and athletic adjustment are important if osteoarthritis is to be prevented.