The Sand Seas of Titan: Cassini RADAR Observations of Longitudinal Dunes

The most recent Cassini RADAR images of Titan show widespread regions (up to 1500 kilometers by 200 kilometers) of near-parallel radar-dark linear features that appear to be seas of longitudinal dunes similar to those seen in the Namib desert on Earth. The Ku-band (2.17-centimeter wavelength) images show approximately 100-meter ridges consistent with duneforms and reveal flow interactions with underlying hills. The distribution and orientation of the dunes support a model of fluctuating surface winds of approximately 0.5 meter per second resulting from the combination of an eastward flow with a variable tidal wind. The existence of dunes also requires geological processes that create sand-sized (100- to 300-micrometer) particulates and a lack of persistent equatorial surface liquids to act as sand traps.

Gout, not induced by diuretics? A case-control study from primary care

BACKGROUND

It is taken for granted that diuretics may induce gout, but there is a general lack of evidence on this topic.

OBJECTIVES

To determine the incidence of gout in patients who use diuretics, taking into account concurrent hypertension and cardiovascular diseases.

METHODS

A case-control study was designed. From a primary care population all patients with a first gout registration (59 men, 11 women; mean (SD) age 55.1 (13.5)) were identified as cases. To relate the occurrence of gout to diuretic use a matched reference series of three controls for each case was compiled. Conditional logistic regression analyses were applied to estimate incidence rate ratios (IRRs) of gout, and 95% confidence intervals (CIs), in subjects with and without diuretic treatment, hypertension, and cardiovascular diseases. Additional stratification analyses were made, particularly in the subjects not using diuretics.

RESULTS

The IRRs of gout in subjects with v those without diuretic treatment, hypertension, heart failure, and myocardial infarction were 2.8 (95% CI 1.2 to 6.6), 2.6 (95% CI 1.2 to 5.6), 20.9 (95% CI 2.5 to 173.8), and 1.9 (95% CI 0.7 to 4.7), respectively. After adjustment, the IRR of gout for diuretic use dropped to 0.6 (95% CI 0.2 to 2.0), while the IRRs of gout for hypertension, heart failure, and myocardial infarction were still >1. This was also the case for subjects with hypertension or myocardial infarction, who had not used diuretics.

CONCLUSION

The results suggest that diuretics do not actually increase the risk of gout. Cardiovascular indications for treatment may have confounded previous inferences.

Organizational characteristics as predictors of work disability: a prospective study among sick employees of for-profit and not-for-profit organizations

INTRODUCTION

This article reports a prospective study that focused on the influence of organizational structure and organizational culture on the outcome of sickness absence, return to work or work disability. Former studies of determinants of work disability hardly have given attention to organizational characteristics and, if so, not following a appropriate prospective design.

METHODS

The study population consisted of 455 employees of 45 for-profit and not-for-profit companies participating in the Maastricht Cohort Study on fatigue at work who were on sick leave for at least 6 weeks. Both independent variables which were type of company, size, centralization of decision making and organizational culture, and covariates, which were sex, age, educational level, fatigue, and chronic illness, were all measured before employees reported sick. The dependent variable outcome of the sickness absence, mainly return to work or work disability, was measured 15 months after reporting sick.

RESULTS

Multilevel logistic regression analysis, with organizational characteristics as level 2 independent variables and demographic and health characteristics as covariates, suggested that the type of company (for-profit/private or not-for-profit/public) is predictive of the outcome of sickness absence (crude OR = 2.21; CI: 1.16-4.20), but this may be partially due to a higher proportion of fatigued and chronically ill employees in not-for-profit companies (adjusted OR = 2.09; CI: 0.93-4.37). Findings about the role of some other organizational characteristics, like organizational culture, were inconclusive.

CONCLUSIONS

Organizational characteristics should next to health characteristics be included in the models of studies which aim at predicting which sick employees are at risk for work disability. To prevent work disability not-for-profit companies might be stimulated to more active return-to-work policy by charging them with the costs of it.

Cassini Radar Views the Surface of Titan

The Cassini Titan Radar Mapper imaged about 1% of Titan's surface at a resolution of approximately 0.5 kilometer, and larger areas of the globe in lower resolution modes. The images reveal a complex surface, with areas of low relief and a variety of geologic features suggestive of dome-like volcanic constructs, flows, and sinuous channels. The surface appears to be young, with few impact craters. Scattering and dielectric properties are consistent with porous ice or organics. Dark patches in the radar images show high brightness temperatures and high emissivity and are consistent with frozen hydrocarbons.

POMT2 mutations cause alpha-dystroglycan hypoglycosylation and Walker-Warburg syndrome

BACKGROUND

Walker-Warburg syndrome (WWS) is an autosomal recessive condition characterised by congenital muscular dystrophy, structural brain defects, and eye malformations. Typical brain abnormalities are hydrocephalus, lissencephaly, agenesis of the corpus callosum, fusion of the hemispheres, cerebellar hypoplasia, and neuronal overmigration, which causes a cobblestone cortex. Ocular abnormalities include cataract, microphthalmia, buphthalmos, and Peters anomaly. WWS patients show defective O-glycosylation of alpha-dystroglycan (alpha-DG), which plays a key role in bridging the cytoskeleton of muscle and CNS cells with extracellular matrix proteins, important for muscle integrity and neuronal migration. In 20% of the WWS patients, hypoglycosylation results from mutations in either the protein O-mannosyltransferase 1 (POMT1), fukutin, or fukutin related protein (FKRP) genes. The other genes for this highly heterogeneous disorder remain to be identified.

OBJECTIVE

To look for mutations in POMT2 as a cause of WWS, as both POMT1 and POMT2 are required to achieve protein O-mannosyltransferase activity.

METHODS

A candidate gene approach combined with homozygosity mapping.

RESULTS

Homozygosity was found for the POMT2 locus at 14q24.3 in four of 11 consanguineous WWS families. Homozygous POMT2 mutations were present in two of these families as well as in one patient from another cohort of six WWS families. Immunohistochemistry in muscle showed severely reduced levels of glycosylated alpha-DG, which is consistent with the postulated role for POMT2 in the O-mannosylation pathway.

CONCLUSIONS

A fourth causative gene for WWS was uncovered. These genes account for approximately one third of the WWS cases. Several more genes are anticipated, which are likely to play a role in glycosylation of alpha-DG.

Coombs-negative severe haemolytic anaemia in an immunocompetent adult following cytomegalovirus infection

Severe haemolysis is a rare, but potentially life-threatening, complication of cytomegalovirus (CMV) infection in immunocompetent adults. Treatment with steroids or immunoglobulins, or even splenectomy, may be justified when an autoimmune mechanism can be identified as the cause of the anaemia. Described here is the case of a previously healthy patient who presented with severe haemolytic anaemia following CMV infection. The patient's haemoglobin level fell to 5.1 g/dl while extensive testing for an autoimmune mechanism remained negative. The patient made a slow but full recovery without additional medication or blood transfusions. This case demonstrates that severe haemolytic anaemia following CMV infection is possible even when presently available tests fail to show autoimmune positivity. In immunocompetent subjects a wait and see policy, with supportive care when necessary, is likely to be justified.

Bioavailability of anthocyanidin-3-glycosides following consumption of elderberry extract and blackcurrant juice

Pharmacokinetic parameters and the bioavailability of several dietary anthocyanins following consumption of blackcurrant juice and elderberry extract were compared exploratorily in 6 healthy volunteers. They were given a single oral dose of either 137 ml of blackcurrant juice (144.8 mg total anthocyanins) or 30 ml of elderberry extract (147.3 mg total anthocyanins). Within 7 hours, the urinary excretion of total anthocyanins (i.e. the sum of all assayed anthocyanidin glycosides) was 0.04% and 0.37% of the administered dose following blackcurrant juice and elderberry extract ingestion, respectively. Pharmacokinetic parameters based on non-compartmental methods for plasma and urine concentrations exhibited higher variability in urinary excretion after ingestion of elderberry extract. Anthocyanin absorption was significantly greater following the intake of elderberry extract than after the intake of blackcurrant juice as shown by the 5.3- and 6.2-fold higher estimates of dose-normalized Cmax and AUC(0-tZ) of total anthocyanins, respectively. The geometric means of t(1/2) were not significantly different following elderberry extract (1.74 h) and blackcurrant juice ingestion (1.73 h, p > 0.05). The urinary excretion rate of intact anthocyanins was fast, appeared to be monoexponential for both blackcurrant juice and elderberry extract. However, in order to evaluate the contribution of anthocyanins to the health-protecting effects of blackcurrant juice and elderberry extract it will be necessary to perform further studies on the unchanged glycosides and their in vivo metabolites in human plasma and urine.

Therapeutic drug monitoring of A77 1726, the active metabolite of leflunomide: serum concentrations predict response to treatment in patients with rheumatoid arthritis

BACKGROUND

Leflunomide is the prodrug of the disease modifying antirheumatic metabolite A77 1726. More than 50% of patients withdraw from leflunomide treatment within one year, mainly because of adverse drug reactions. Therapeutic drug monitoring of A77 1726 may be useful in predicting the efficacy of leflunomide treatment.

OBJECTIVE

To study the relation between A77 1726 steady state serum concentrations and disease activity using the 28 joint (DAS28) response.

METHODS

Outpatients with rheumatoid arthritis on a stable leflunomide dose for >4 months were included. DAS28 score and adverse drug reactions were recorded. Blood samples were taken for determination of A77 1726 concentrations. The primary end point was the relation of serum A77 1726 concentrations with DAS28 response category.

RESULTS

Serum A77 1726 concentrations were determined in 52 patients. A receiver operating characteristic (ROC) curve showed an area under the curve (AUC) of 0.73 (95% confidence interval, 0.54 to 0.93) (p<0.05). The sensitivity exceeded 99% at concentrations below 16 mg/l. DAS28 values at the point of sampling showed no relation with A77 1726 concentrations (AUC of the ROC curve = 0.50 (0.33 to 0.67) (NS)).

CONCLUSIONS

A77 1726 steady state serum concentrations show a relation with DAS28 response. Determination of serum A77 1726 concentrations in patients with insufficient response to treatment may help when decisions have to be made about continuation of treatment or dose adjustment.

The paediatric liver transplantation program at the Université catholique de Louvain

The Paediatric Liver Transplant Program at Saint-Luc University Clinics constitutes a substantial single centre experience, including 667 transplantations performed between March 1984 and April 2003, and the history of this program reflects the tremendous progress in this field since twenty years. Liver transplantation in children constitutes a considerable undertaking and its results depend on multiple, intermingled risk factors. An analysis of the respective impact of several surgical and immunological parameters on patient/graft outcome and allograft rejection after paediatric liver transplantation showed a significant learning curve effect as well as the respective impact of pre-transplant diagnosis on survival and of primary immunosuppression on the rejection incidence. The introduction of living related liver transplantation in 1993 not only permitted to provide access to liver replacement in as many as 74% more candidate recipients, but also resulted in better graft survival and reduced retransplantation rate. The results of a recent pilot study suggest that steroid avoidance is not harmful, and could even be beneficial for paediatric liver recipients, particularly regarding growth, and that combining tacrolimus with basiliximab (anti-CD25 chimeric monoclonal antibody) for steroid substitution appears to constitute a safe alternative in this context. The long-term issues represent the main future challenges in the field, including the possibility of a full rehabilitation through immunosuppression withdrawal and tolerance induction, the development of adolescence transplant medicine, and the risk of early atherogenesis in the adulthood.

Gout, just a nasty event or a cardiovascular signal? A study from primary care

OBJECTIVE

Our aim was to examine the relationship between gout on the one hand and cardiovascular diseases and cardiovascular risk indicators on the other.

METHODS

A case-control study was carried out in an aggregate primary care population of approximately 12 000 patients from four Dutch general practices, with follow-up of the cases free of cardiovascular diseases at the time of the first registered episode of gout. The subjects comprised 261 patients with a first episode of gout, 170 of whom were without prevalent cardiovascular diseases, and two control patients for each case matched for age, sex and practice. In the case-control study, the main outcome measures were the prevalence of cardiovascular morbidity (angina pectoris, myocardial infarction, heart failure, cerebrovascular accident, transient ischaemic attack, peripheral vascular disease), hypertension, diabetes mellitus, obesity and hypercholesterolaemia; in the follow-up study, the main outcome measure was the incidence of cardiovascular morbidity.

RESULTS

Thirty-five percent of 261 gout patients and 26% of 522 controls had one or more prevalent cardiovascular diseases. Compared with controls, patients had a higher prevalence of hypertension (43% versus 18%), hypercholesterolaemia (14% versus 6%) and obesity (56% versus 30%). A total of 170 gout patients without prevalent cardiovascular diseases (compared with 340 controls) had a higher prevalence of hypertension (39% versus 14%), hypercholesterolaemia (8% versus 4%), diabetes mellitus (5% versus 1%) and obesity (52% versus 27%). The first occurrence of a cardiovascular disease (real end-point) was seen in 26% of the patients free of cardiovascular morbidity and in 21% of the controls. This difference was not significant. In a Cox proportional hazard model, controlling for the cardiovascular risk indicators, gout did not prove to be an independent determinant for the development of cardiovascular disease.

CONCLUSION

Gout was found to be associated with cardiovascular diseases and with cardiovascular risk indicators, without evidence of it being an independent risk indicator itself. A gout attack should be an incentive to assess the cardiovascular risk profile, when a patient seeks medical help.

Pediatric liver transplantation for biliary atresia: results of primary grafts in 328 recipients

PURPOSE

The purpose of this study was to assess the overall results of recipients undergoing transplantation for biliary atresia (BA), according to age, surgical techniques, and transplant eras, and to identify the prognostic factors affecting outcome.

METHODS

Between 1984 and 2000, 328 pediatric recipients with BA who underwent orthotopic liver transplantation (OLT) were reviewed. Median age at OLT was 1.5 years (range, 0.4-14.5 years). Kasai hepatoportoenterostomy (KHPE) had been previously performed in 285 (87%) children. Regarding surgical techniques, 125 (38%) children received a whole-liver graft, 128 (39%) received a reduced-size graft, 16 (5%) received a split-liver graft, and 59 (18%) received a living-related (LR) donor graft.

RESULTS

Overall actuarial patient survivals were 87%, 83%, and 81% at 1, 5, and 10 years, respectively. One-year patient survivals in children undergoing transplantation at the different age ranges were 85% (under 1 year), 86% (1-3 years), 83% (3-6 years), 100% (6-10 years), and 100% (beyond 10 years) (not significant). One-year patient survivals for the different transplant eras were 75% (1984-1988), 85% (1989-1992), 93% (1993-1996), and 98% (1997-2000) (P=0.0001). Multivariate analysis demonstrated that pretransplant recipient weight (P=0.004), indication for OLT (P=0.083), and age at OLT (P=0.024) predicted patient survival. The type of baseline calcineurin inhibitor (tacrolimus) and the age at OLT (beyond 6 years) were significantly associated with a better graft survival.

CONCLUSIONS

Best results in children undergoing transplantation beyond 6 years indicate the importance of performing a KHPE as the first therapeutic step in BA; innovative surgical techniques, particularly LR donor graft, allowed successful transplantation in infants with early failure of KHPE.

Membrane type-1 matrix metalloproteinase and TIMP-2 in tumor angiogenesis

The matrix metalloproteinases (MMPs) constitute a multigene family of over 23 secreted and cell-surface associated enzymes that cleave or degrade various pericellular substrates. In addition to virtually all extracellular matrix (ECM) compounds, their targets include other proteinases, chemotactic molecules, latent growth factors, growth factor-binding proteins and cell surface molecules. The MMP activity is controlled by the physiological tissue inhibitors of MMPs (TIMPs). There is much evidence that MMPs and their inhibitors play a key role during extracellular remodeling in physiological situations and in cancer progression. They have other functions that promoting tumor invasion. Indeed, they regulate early stages of tumor progression such as tumor growth and angiogenesis. Membrane type MMPs (MT-MMPs) constitute a new subset of cell surface-associated MMPs. The present review will focus on MT1-MMP which plays a major role at least, in the ECM remodeling, directly by degrading several of its components, and indirectly by activating pro-MMP2. As our knowledge on the field of MT1-MMP biology has grown, the unforeseen complexities of this enzyme and its interaction with its inhibitor TIMP-2 have emerged, often revealing unexpected mechanisms of action.

Predicting inhibition and inactivation of Yersinia enterocolitica through lactic acid production by Lactobacillus sakei

In food technology, there is a need for models taking into account the interactions between microorganisms, in order to correctly predict the safety and shelf life of food products. When leaving these interactions out of consideration, a discrepancy between the model prediction and the actual microbial evolution may occur for certain types of food products. In this study, a model describing the inhibition of the pathogenic Yersinia enterocolitica in mono- and coculture with Lactobacillus sakei was extended to describe also the subsequent inactivation of Y. enterocolitica. During the development of a suitable model structure to describe the inactivation process, biological knowledge about this process was incorporated. The extended model was able to predict evolution of Y. enterocolitica in coculture as well as in monoculture.

Ultra-relativistic electrons in Jupiter's radiation belts

Ground-based observations have shown that Jupiter is a two-component source of microwave radio emission: thermal atmospheric emission and synchrotron emission from energetic electrons spiralling in Jupiter's magnetic field. Later in situ measurements confirmed the existence of Jupiter's high-energy electron-radiation belts, with evidence for electrons at energies up to 20[?]MeV. Although most radiation belt models predict electrons at higher energies, adiabatic diffusion theory can account only for energies up to around 20[?]MeV. Unambiguous evidence for more energetic electrons is lacking. Here we report observations of 13.8[?]GHz synchrotron emission that confirm the presence of electrons with energies up to 50[?]MeV; the data were collected during the Cassini fly-by of Jupiter. These energetic electrons may be repeatedly accelerated through an interaction with plasma waves, which can transfer energy into the electrons. Preliminary comparison of our data with model results suggests that electrons with energies of less than 20[?]MeV are more numerous than previously believed.

Effects of dexamethasone on proliferation of and fibronectin synthesis by human primary prostatic stromal cells in vitro

Glucocorticoids are anti inflammatory stress hormones and have been suggested to be involved in a large number of pathological processes. To test the effects of glucocorticoids on stromal prostatic cell growth and proliferation in vitro, the influence of a synthetic glucocorticoid (dexamethasone, dex) on recently established human primary cells from prostatic stroma (hPCPs) was analysed. The localization and distribution of the glucocorticoid receptor (GR) was investigated by immunohistochemistry. In addition, expression of the active isoform of the receptor (alpha-GR) was examined by reverse transcription PCR, and the effect of different doses of dex on proliferation of the stromal cells evaluated using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) and amido black assays. alpha-GR mRNA was expressed by the hPCPs, and the GR protein was detected in the cytoplasm and nucleus of these cells. Incubating the cells with dex resulted in an enhanced cell proliferation that was mainly restricted to the fibroblasts. Moreover, fibronectin (FN) gene expression and secretion of the protein was increased by high doses of dex (> or = 10(-8) M), whereas low doses of dex (10(-10)M) showed no effect. Human prostatic stromal cells show sensitivity to dex in vitro, resulting in an increase in cell proliferation and FN synthesis. The authors assume that locally accumulating glucocorticoids can also influence the regulation of cell growth and extracellular matrix synthesis in the human prostate in vivo and may play a role in the pathologically altered prostate.