General practitioner reported incidence of Lyme carditis in the Netherlands

Background

Between 1994 and 2009, incidence rates of general practitioner (GP) consultations for tick bites and erythema migrans, the most common early manifestation of Lyme borreliosis, have increased substantially in the Netherlands. The current article aims to estimate and validate the incidence of GP-reported Lyme carditis in the Netherlands.

Methods

We sent a questionnaire to all GPs in the Netherlands on clinical diagnoses of Lyme borreliosis in 2009 and 2010. To validate and adjust the obtained incidence rate, medical records of cases of Lyme carditis reported by GPs in this incidence survey were reviewed and categorised according to likelihood of the diagnosis of Lyme carditis.

Results

Lyme carditis occurred in 0.2 % of all patients with GP-reported Lyme borreliosis. The adjusted annual incidence was six GP-reported cases of Lyme carditis per 10 million inhabitants, i.e. approximately ten cases per year in 2009 and 2010.

Conclusions

We report the first incidence estimate for Lyme carditis in the Netherlands, validated by a systematic review of the medical records. Although Lyme carditis is an uncommon manifestation of Lyme borreliosis, physicians need to be aware of this diagnosis, in particular in countries where the incidence of Lyme borreliosis has increased during the past decades.     

The identification of biomarkers differentiating Mycobacterium tuberculosis and non-tuberculous mycobacteria via thermally assisted hydrolysis and methylation gas chromatography–mass spectrometry and chemometrics

Infections with non-tuberculous mycobacteria (NTM) are increasing, particularly among immune-compromised patients and those with damaged lungs. Mycobacterium tuberculosis complex (MTB) strains, however, remain the most common cause of mycobacterial infection. A rapid method of distinguishing MTB from NTM is required for correct diagnosis and tuberculosis management. We have developed an automated procedure based on thermally-assisted hydrolysis and methylation followed by gas chromatography–mass spectrometry (THM–GC–MS) and advanced chemometrics to differentiate MTB from NTM. We used early cultures of mycobacteria in this first step towards the direct identification of these bacteria in sputum using a hand-held portable device. To build a classification model, we used 44 strains including 15 MTB and 29 NTM. A matrix of the aligned dataset containing ~45,700 features (retention time/mass pairs) for the 44 observations was submitted to partial least squares discriminant analysis (PLS–DA). We could reduce the number of features down to 250 without compromising the accuracy of the model. Twenty different compounds were found through mass spectral interpretation of these 250 features. Some of these compounds have not been linked to tuberculosis before, others have been proposed previously as diagnostic biomarkers for this disease. We have built a final model based on our proposed biomarkers that performed with 95 % accuracy in distinguishing MTB from NTM in early cultures. Since all these biomarkers have been chemically identified, work can proceed towards the development of simpler, bed-side diagnostic tests to differentiate MTB from NTM in sputum.     

Die Mutation im Lichte der biomechanischen Erblichkeitstheorie

Ohne ZusammenfassungGehalten auf der 10. Jahresversammlung in Göttingen.     

Evolution of class B floral homeotic proteins: obligate heterodimerization originated from homodimerization

The class B floral homeotic genes from the higher eudicot model systems Arabidopsis and Antirrhinum are involved in specifying the identity of petals and stamens during flower development. These genes exist in two different types termed DEF- and GLO-like genes. The proteins encoded by the class B genes are stable and functional in the cell only as heterodimeric complexes of a DEF- and a GLO-like protein. In line with this, heterodimerization is obligate for DNA binding in vitro. The genes whose products have to heterodimerize to be stable and functional are each other's closest relatives within their genomes. This suggests that the respective genes originated by gene duplication, and that heterodimerization is of relative recent origin and evolved from homodimerization. To test this hypothesis we have investigated the dimerization behavior of putative B proteins from phylogenetic informative taxa, employing electrophoretic mobility shift assays and the yeast two-hybrid system. We find that an ancestral B protein from the gymnosperm Gnetum gnemon binds DNA in a sequence-specific manner as a homodimer. Of the two types of B proteins from the monocot Lilium regale, the GLO-like protein is still able to homodimerize, whereas the DEF-like protein binds to DNA only as a heterodimeric complex with the GLO-like protein. These data suggest that heterodimerization evolved in two steps after a gene duplication that gave rise to DEF- and GLO-like genes. Heterodimerization may have originated after the gymnosperm-angiosperm split about 300 MYA but before the monocot-eudicot split 140-200 MYA. Heterodimerization may have become obligate for both types of flowering plant B proteins in the eudicot lineage after the monocot-eudicot split.     

Intestinal Fatty Acid-Binding Protein as a Diagnostic Marker for Complicated and Uncomplicated Necrotizing Enterocolitis: A Prospective Cohort Study

Background

Early NEC symptoms are non-specific and diagnostic tests lack discriminative power. Intestinal fatty acid-binding protein (I-FABP), mainly located in small bowel enterocytes, is released into the blood following NEC-associated enterocyte disruption. Aim of this prospective cohort trial was to determine the diagnostic value of I-FABP measured in plasma (I-FABPp) and urine (I-FABPu) for the presence of NEC, to evaluate I-FABP levels during NEC development, and to assess its prognostic value for the progression from suspected to complicated disease.

Methods

Between 2010 and 2012 we prospectively enrolled neonates with suspected NEC. We measured I-FABP levels eight-hourly from onset of suspected NEC for at least 48 hours, or until surgery. NEC diagnosis was confirmed radiologically or during operation. We defined NEC as complicated if it resulted in surgery and/or death. We determined disease course and diagnostic I-FABP cut-off points.

Results

The study comprised 37 neonates (24M, 13F), gestational age 28 (24–36) weeks, birth weight 1190 (570–2,400) grams. We found significantly higher I-FABPp and I-FABPu levels in NEC patients (n = 22) than in patients with other diagnoses (n = 15). Cut-off values for diagnosing NEC were 9 ng/mL I-FABPp and 218 ng/mL I-FABPu, with corresponding likelihood ratios (LRs) of 5.6 (95% CI 0.89–35) and 5.1 (95% CI 0.73–36), respectively. I-FABP levels were highest in the first eight hours after symptom onset and gradually decreased over time. Cut-off values for complicated disease were 19 ng/mL I-FABPp and 232 ng/mL I-FABPu, with LRs of 10 (95% CI 1.6–70) and 11 (95% CI 1.6–81), respectively.

Conclusions

Both plasma and urinary I-FABP levels specifically identify NEC in preterm infants prior to appearance of diagnostic radiological signs suggestive for NEC. Moreover, serial I-FABP measurements accurately predict development of complicated disease.     

Insulin-induced translocation of CD36 to the plasma membrane is reversible and shows similarity to that of GLUT4

In cardiac and skeletal muscles, insulin regulates the uptake of long-chain fatty acid (LCFA) via the putative LCFA transporter CD36. Biochemical studies propose an insulin-induced translocation of CD36 from intracellular pools to the plasma membrane (PM), similar to glucose transporter 4 (GLUT4) translocation. To characterize insulin-induced CD36 translocation in intact cells, Chinese hamster ovary (CHO) cells stably expressing CD36 or myc-tagged GLUT4 (GLUT4myc) were created. Immuno-fluorescence microscopy revealed CD36 to be located both intracellularly (in--at least partially--different compartments than GLUT4myc) and at the PM. Upon stimulation with insulin, CD36 translocated to a PM localization similar to that of GLUT4myc; the increase in PM CD36 content, as quantified by surface-protein biotinylation, amounted to 1.7-fold. The insulin-induced CD36 translocation was shown to be phosphatidylinositol-3 kinase-dependent, and reversible (as evidenced by insulin wash-out) in a similar time frame as that for GLUT4. The expression of GLUT4myc in non-stimulated cells, and the insulin-induced increase in PM GLUT4myc correlated with increased deoxyglucose uptake. By contrast, CD36 expression in non-stimulated cells and the insulin-induced increase in PM CD36 were not paralleled by a rise in LCFA uptake, suggesting that in these cells, such increase requires additional proteins, or a protein activation step. Taken together, this study is the first to present morphological evidence for CD36 translocation, and shows this process to resemble GLUT4 translocation.     

Unique occurrence of pectin-like fibrillar cell wall deposits in xylem fibres of poplar

Using light and electron microscopic techniques, we studied the unique occurrence of fibrillar cell wall deposits in mature xylem fibres from poplar. These cell wall deposits lined the lumen-facing side of the wall, mainly in fibres next to vessel elements. Different lines of evidence point to the pectin-like nature of these fibrillar cell wall deposits. First, specific staining by Alcian Blue 8GX, a dye with high affinity for pectic substances. Second, the strongly reduced staining of the cell wall deposits in microscopic sections treated with pectolytic enzyme. Third, concomitant staining of pits, which are known to consist mainly of pectic substances. Given the pectin-like nature of the fibrillar cell wall deposits as well as their preferred occurrence in fibres neighbouring water-conducting vessel elements, a function for the fibrillar cell wall deposits in lateral water diffusion and stem water storage is hypothesised. The hypothesis is supported by the increased abundance of these cell wall deposits in wood tissue of a drought-sensitive poplar species.     

Cytological study of the kidney ischemic lesions in rats

The course of reparative regeneration after 5/6 nephrectomy and use of low-dose radiation has been studied by means of light and electron microscopy. The experiments were performed on 30 male Wistar rats. All animal procedures were conducted after approval of the protocol by the animal Studies Ethics Committee of the University of Tartu. Renal ablation was then accomplished by right nephrectomy and selective ligation of extrarenal branches of the left renal artery such that approximately 2/3 of the left kidney was infracted. All together 30 rats were randomised after the surgery and divided into two groups matched for age and body weight at week 0 and studied during 2, 4 and 8 weeks: groups I (nephrectomized, n = 15), groups II (nephrectomized and irradiated, n = 15). Left kidney of II groups rats was irradiated (60Co) 24 h after surgery in anaesthetized (Brietal) animals with 3 Gy in a single dose. As a result of experimentally induced ischemia destruction of renal corpuscles, perishing of tubular epithelial cells and and proliferation of connective tissue is followed. Reparative regeneration is based on aseptic inflammation, duration of its phases depends on the extent of organ impairment. In nephrectomized rats parallel to reparative regeneration, necrosis and deposition of calcium is found in the cortical substance. Calcium plays important role in kidney metabolism and its increased content is characteristic to degenerative changes. The experiments reveal that use of low-dose radiation does not accelerate process of reparative regeneration in rat kidney.     

Disentangling community functional components in a litter‐macrodetritivore model system reveals the predominance of the mass ratio hypothesis

Recent investigations have shown that two components of community trait composition are important for key ecosystem processes: (i) the community‐weighted mean trait value (CWM), related to the mass ratio hypothesis and dominant trait values in the community, and (ii) functional diversity (FD), related to the complementarity hypothesis and the divergence of trait values. However, no experiments controlling for the inherent dependence between CWM and FD have been conducted so far. We used a novel experimental framework to disentangle the unique and shared effects of CWM and FD in a leaf litter‐macrodetritivore model system. We manipulated isopod assemblages varying in species number, CWM and FD of litter consumption rate to test the relative contribution of these community parameters in the decomposition process. We showed that CWM, but also the combination of CWM and FD, is a main factor controlling litter decomposition. When we tested individual biodiversity components separately, CWM of litter consumption rate showed a significant effect on decomposition, while FD and species richness alone did not. Our study demonstrated that (i) trait composition rather than species diversity drives litter decomposition, (ii) dominant trait values in the community (CWM) play a chief role in driving ecosystem processes, corroborating the mass ratio hypothesis, and (iii) trait dissimilarity can contribute in modulating the overall biodiversity effects. Future challenge is to assess whether the generality of our finding, that is, that dominant trait values (CWM) predominate over trait dissimilarity (FD), holds for other ecosystem processes, environmental conditions and different spatial and temporal scales.