Effects of Mesolithic hunter-gatherers on local vegetation in a non-uniform glacio-isostatic land uplift area, northern Sweden

The oldest early Mesolithic settlements found so far (i.e. 8600 b.p.) in the interior of northern Sweden, in the province of Norrbotten, have been discovered through the application of a model simulating glacio-isostatic land uplift. The objective of this study was to investigate, through pollen and charred particle analyses, vegetation composition and the influence of man on vegetation and fire pattern in the vicinity of two of these early settlements. Early Holocene vegetation was characterised by Betula, Hippophaë and Salix-species, but no initial impact by hunter-gatherers on vegetation was detected. Subsequently Betula and Pinus became dominant but abrupt changes in the tree layer followed, Poaceae, Hippophaë and Salix-species increased, and Humulus occurred. These changes, which were synchronous with dates of archaeological findings at the settlements, indicated local vegetation changes caused by man. The relationship between these changes and fire was, however, subtle. Eventually Pinus forests became dominant and human impact on vegetation became less apparent. It is concluded that the impact of early Mesolithic hunter-gatherers on vegetation was detectable, but that their effect on fire pattern was difficult to evaluate. Further, we show that the glacio-isostatic land uplift must be considered in the search for Mesolithic settlements in areas previously covered by the Weichselian Ice, and that the process has influenced the biological archives through re-deposition of material.     

Evolution of a carbohydrate binding module into a protein-specific binder

A carbohydrate binding module, CBM4-2, derived from the xylanase (Xyn 10A) of Rhodothermus marinus has been used as a scaffold for molecular diversification. Its binding specificity has been evolved to recognise a quite different target, a human monoclonal IgG4. In order to understand the basis for this drastic change in specificity we have further investigated the target recognition of the IgG4-specific CBMs. Firstly, we defined that the structure target recognised by the selected CBM-variants was the protein and not the carbohydrates attached to the glycoprotein. We also identified key residues involved in the new specificity and/or responsible for the swap in specificity, from xylan to human IgG4. Specific changes present in all these CBMs included mutations not introduced in the design of the library from which the specific clones were selected. Reversion of such mutations led to a complete loss of binding to the target molecule, suggesting that they are critical for the recognition of human IgG4. Together with the mutations introduced at will, they had transformed the CBM scaffold into a protein binder. We have thus shown that the scaffold of CBM4-2 is able to harbour molecular recognition for either carbohydrate or protein structures.     

Epididymal expression of the forkhead transcription factor Foxi1 is required for male fertility

An essential aspect of male reproductive capacity is the immediate availability of fertilization-ready spermatozoa. To ensure this, most mammals rely on post-testicular sperm maturation. In epididymis, germ cells are matured and stored in a quiescent state that readily can be altered to produce active spermatozoa. This depends on active proton secretion into the epididymal lumen. We have identified Foxi1 as an important regulator of gene expression in narrow and clear cells-the major proton secretory cells of epididymal epithelia. Foxi1 appears to be required for the expression of the B1-subunit of the vacuolar H+ -ATPase proton pump and for carbonic anhydrase II as well as the chloride/bicarbonate transporter pendrin. Using transfection experiments, we have identified a Foxi1 binding cis-element in the ATP6V1B1 (encoding the B1-subunit) promoter that is critical for reporter gene activation. When this site is mutated to eliminate Foxi1 binding, activation is also abolished. As a consequence of defect Foxi1-dependent epididymal sperm maturation, we demonstrate that spermatozoa from Foxi1 null males fail to reach the female genital tract in sufficient number to allow fertilization.     

IGF-1R tyrosine kinase expression and dependency in clones of IGF-1R knockout cells (R-)

Insulin-like growth factor 1 receptor (IGF-1R) plays many crucial roles in cancer, like anti-apoptotic activity and necessity for transformation. IGF-1R knockout cells (R-) represent a useful tool for molecular mapping of biological properties of the receptor. R- cells have been shown to be refractory to transformation by viral and cellular oncogenes, highlighting the necessity of this receptor for transformation. Surprisingly, more recent studies have shown that these cells can undergo spontaneous transformation. This observation raises the question as whether R- cells over the years have acquired some properties mimicking those of IGF-1R. Using an IGF-1R inhibitor (cyclolignan PPP) we have identified clones of R- (R-s) that are sensitive to this compound. Since, PPP is closely related to podophyllotoxin, which is an efficient microtubule inhibitor, we first investigated if such a mechanism could explain the sensitivity to PPP. However, highly purified PPP showed no or very slight tubulin binding. Further analysis of R-s revealed expression of a 90 kDa protein being reactive to IGF-1R beta-subunit antibodies. This protein was weakly but constitutively tyrosine phosphorylated and was downregulated by siRNA targeting IGF-1R. This downregulation was paralleled by decreased R-s survival. Taken together, our study suggests that clones of R- express IGF-1R activity and dependency, which in turn may explain that R- can undergo spontaneous transformation.     

Proinsulin C-peptide interferes with insulin fibril formation

Insulin aggregation can prevent rapid insulin uptake and cause localized amyloidosis in the treatment of type-1 diabetes. In this study, we investigated the effect of C-peptide, the 31-residue peptide cleaved from proinsulin, on insulin fibrillation at optimal conditions for fibrillation. This is at low pH and high concentration, when the fibrils formed are regular and extended. We report that C-peptide then modulates the insulin aggregation lag time and profoundly changes the fibril appearance, to rounded clumps of short fibrils, which, however, still are Thioflavine T-positive. Electrospray ionization mass spectrometry also indicates that C-peptide interacts with aggregating insulin and is incorporated into the aggregates. Hydrogen/deuterium exchange mass spectrometry further reveals reduced backbone accessibility in insulin aggregates formed in the presence of C-peptide. Combined, these effects are similar to those of C-peptide on islet amyloid polypeptide fibrillation and suggest that C-peptide has a general ability to interact with amyloidogenic proteins from pancreatic β-cell granules. Considering the concentrations, these peptide interactions should be relevant also during physiological secretion, and even so at special sites post-secretory or under insulin treatment conditions in vivo.     

Hypertension, cardiovascular risk and polymorphisms in genes controlling the cytochrome P450 pathway of arachidonic acid: A sex-specific relation?

Hypertension is a multifactorial disease in which the interplay of genetic and environmental factors that maintain blood pressure stable throughout life is altered. Cytochrome P450 (CYP)-derived metabolites of arachidonic acid such as epoxyeicosatrienoic acids (EETs) and 20-hydroxyeicosatetraenoic acid (20-HETE), active on vascular tone, endothelial function and renal sodium reapportion, have been identified as candidate mediators in the development of hypertension in several animal models, with remarkable sex-specific effect. Several SNPs, some recognized as functional, in human genes implicated in EETs/20-HETE biosynthesis and metabolism, such as CYP2J2 and CYP4A11, have been tested for association with blood pressure, hypertension and its long-term cardiovascular consequences in different populations, with conflicting results. A sex-specific effect, related to CYP4F2 polymorphisms and expression, has been observed in association studies. This finding indicates that altered 20-HETE bioactivity underlay the excess of hypertension and associated vascular events observed in men with respect to women and is consistent with the results from experimental models. Further epidemiological and mechanistic studies are required to confirm the effect of lipid mediators on blood pressure in humans and define the mechanisms of a putative sex-specific effect.     

The impact of asymptomatic helminth co-infection in patients with newly diagnosed tuberculosis in north-west ethiopia

Background

Areas endemic of helminth infection, tuberculosis (TB) and HIV are to a large extent overlapping. The aim of this study was to assess the impact of asymptomatic helminth infection on the immunological response among TB patients with and without HIV, their house hold contacts and community controls.

Methodology

Consecutive smear positive TB patients (n = 112), their household contacts (n = 71) and community controls (n = 112) were recruited in Gondar town, Ethiopia. Stool microscopy, HIV serology, serum IgE level, eosinophil and CD4 counts were performed and tuberculosis patients were followed up for 3 months after initiation of anti-TB treatment.

Results

Helminth co-infection rate was 29% in TB patients and 21% in both community control and household contacts (p = 0.3) where Ascaris lumbricoides was the most prevalent parasite. In TB patients the seroprevalence of HIV was 47% (53/112). Eosinophilia and elevated IgE level were significantly associated with asymptomatic helminth infection. During TB treatment, the worm infection rate of HIV+/TB patients declined from 31% (10/32) at week 0 to 9% (3/32) at week 2 of TB treatment, whereas HIV−/TB patients showed no change from baseline to week 2, 29% (13/45) vs. 22.2% (10/45). This trend was stable at week 8 and 12 as well.

Conclusion

One third of smear positive TB patients were infected with helminths. Eosinophilia and elevated IgE level correlated with asymptomatic worm infection, indicating an effect on host immunity. The rate of worm infection declined during TB treatment in HIV+/TB co-infected patients whereas no decline was seen in HIV−/TB group.     

17β-Hydroxysteroid dehydrogenase type 14 is a predictive marker for tamoxifen response in oestrogen receptor positive breast cancer

Introduction

17β-hydroxysteroid dehydrogenases (17βHSDs) are important enzymes regulating the pool of bioactive steroids in the breast. The current study was undertaken in order to evaluate implications of 17βHSD14 in breast cancer, measuring 17βHSD14 protein expression in breast tumours.

Methods

An antibody targeting the 17βHSD14 antigen was generated and validated using HSD17B14-transfected cells and a peptide-neutralising assay. Tissue microarrays with tumours from 912 post-menopausal women diagnosed with lymph node-negative breast cancer, and randomised to adjuvant tamoxifen or no endocrine treatment, were analysed for 17βHSD14 protein expression with immunohistochemistry.

Results

Results were obtained from 847 tumours. Patients with oestrogen positive tumours with high 17βHSD14 expression had fewer local recurrences when treated with tamoxifen (HR 0.38; 95% C.I. 0.19–0.77, p = 0.007) compared to patients with lower tumoural 17βHSD14 expression, for whom tamoxifen did not reduce the number of local recurrences (HR 1.19; 95% C.I. 0.54–2.59; p = 0.66). No prognostic importance of 17βHSD14 was seen for systemically untreated patients.

Conclusions

Using a highly specific validated antibody for immunohistochemical analysis of a large number of breast tumours, we have shown that tumoural expression levels of 17βHSD14 can predict the outcome of adjuvant tamoxifen treatment in terms of local recurrence-free survival in patients with lymph node-negative ER+ breast cancer. The results need be verified to confirm any clinical relevance.     

Common genetic variations in the NALP3 inflammasome are associated with delayed apoptosis of human neutrophils

Background

Neutrophils are key-players in the innate host defense and their programmed cell death and removal are essential for efficient resolution of inflammation. These cells recognize a variety of pathogens, and the NOD-like receptors (NLRs) have been suggested as intracellular sensors of microbial components and cell injury/stress. Some NLR will upon activation form multi-protein complexes termed inflammasomes that result in IL-1β production. NLR mutations are associated with auto-inflammatory syndromes, and our previous data propose NLRP3 (Q705K)/CARD-8 (C10X) polymorphisms to contribute to increased risk and severity of inflammatory disease by acting as genetic susceptibility factors. These gene products are components of the NALP3 inflammasome, and approximately 6.5% of the Swedish population are heterozygote carriers of these combined gene variants. Since patients carrying the Q705K/C10X polymorphisms display leukocytosis, the aim of the present study was to find out whether the inflammatory phenotype was related to dysfunctional apoptosis and impaired clearance of neutrophils by macrophages.

Methods and Findings

Patients carrying the Q705K/C10X polymorphisms displayed significantly delayed spontaneous as well as microbe-induced apoptosis compared to matched controls. Western blotting revealed increased levels and phosphorylation of Akt and Mcl-1 in the patients'' neutrophils. In contrast to macrophages from healthy controls, macrophages from the patients produced lower amounts of TNF; suggesting impaired macrophage clearance response.

Conclusions

The Q705K/C10X polymorphisms are associated with delayed apoptosis of neutrophils. These findings are explained by altered involvement of different regulators of apoptosis, resulting in an anti-apoptotic profile. Moreover, the macrophage response to ingestion of microbe-induced apoptotic neutrophils is altered in the patients. Taken together, the patients display impaired turnover and clearance of apoptotic neutrophils, pointing towards a dysregulated innate immune response that influences the resolution of inflammation. The future challenge is to understand how microbes affect the activation of inflammasomes, and why this interaction will develop into severe inflammatory disease in certain individuals.