A Novel Magnetic Stimulator Increases Experimental Pain Tolerance in Healthy Volunteers - A Double-Blind Sham-Controlled Crossover Study

The ‘complex neural pulse’^TM (CNP) is a neuromodulation protocol employing weak pulsed electromagnetic fields (PEMF). A pioneering paper reported an analgesic effect in healthy humans after 30 minutes of CNP-stimulation using three nested whole head coils. We aimed to devise and validate a stimulator with a novel design entailing a multitude of small coils at known anatomical positions on a head cap, to improve applicability. The main hypothesis was that CNP delivery with this novel device would also increase heat pain thresholds. Twenty healthy volunteers were enrolled in this double-blind, sham-controlled, crossover study. Thirty minutes of PEMF (CNP) or sham was applied to the head. After one week the other treatment was given. Before and after each treatment, primary and secondary outcomes were measured. Primary outcome was heat pain threshold (HPT) measured with thermal quantitative sensory testing. Other outcomes were warmth detection threshold, and aspects of cognition, emotion and motor performance. As hypothesized heat pain threshold was significantly increased after the PEMF stimulation. All other outcomes were unaltered by the PEMF but there was a trend level reduction of cognitive performance after PEMF stimulation as measured by the digit-symbol substitution task. Results from this pilot study suggest that our device is able to stimulate the brain and to modulate its function. This is in agreement with previous studies that used similar magnetic field strengths to stimulate the brain. Specifically, pain control may be achieved with PEMF and for this analgesic effect, coil design does not appear to play a dominant role. In addition, the flexible configuration with small coils on a head cap improves clinical applicability.

Trial Registration

Dutch Cochrane Centre NTR1093     

Methyl farnesoate induced ovarian maturation in the spider crab,Libinia emarginata

Summary

To overcome the problem of getting crustaceans to reproduce in captivity, eyestalk ablation or X-organ sinus gland removal is commonly utilized in commercially important species such as shrimp. We have investigated the effect of unilateral and bilateral eyestalk ablation on methyl farnesoate (MF) production by mandibular organs (MOs) and on ovarian maturation in female spider crabs Libinia emarginata, a useful model since these animals are in a terminal molt and are devoid of a functional Y-organ. Non-reproductive, over-wintering female L. emarginata were induced to be reproductive by feeding and increasing the holding temperature to stimulate the endocrine system. In addition, we removed X-organ sinus glands by eyestalk ablation either unilaterally (UEA) or bilaterally (BEA) to further stimulate MF synthesis by MOs. Endogenous MF in the hemolymph was extracted and quantified by means of HPLC and in some cases by GC/MS. Oocyte growth and egg quality were studied simultaneously to determine how they were related to MF levels found during vitellogenesis. The initial MF concentration in unablated controls was low, 0.31 ng/ml of hemolymph, and this increased (p<0.05) to about 1 ng/ml by 2 weeks, remaining at about that level for the remainder of the experiment. Eyestalk ablation significantly stimulated MF concentrations by week 1 to nearly 2 and 3.5ng/ml in the UEA (p <0.01) and BEA (p <0.001) animals, respectively. Oocytes appeared to respond to increased MF levels, as ovarian maturation was initiated from the point at which MF increased (p <0.05). Thereafter, the rate of oocyte growth was directly correlated with the extent of elevation of MF. The gonado-somatic index [(GSI) = gonad weight/body weight × 100] of controls at the start was about 1.5 and increased to 6.5 by week 4. Mature oocytes were reached at a GSI around 7. Oocyte maturation was accomplished at week 2 in BEA, week 3 in UEA, and later than week 4 in controls. After maturation, oocytes started to degrade in some ablated animals, particularly in the bilaterally ablated ones where the highest MF concentrations were observed. These data indicate that MF elevations are required for stimulating ovarian maturation in Crustacea. MF appears to accelerate gonad development during the vitellogenic process, but may be deleterious at high concentrations. These results have a significant and important application and implications for aquaculture.     

Observation of some key stages of the embryonic development of Biomphalaria straminea (Dunker, 1848) (Molluska,Planorbidae)

Summary

Biomphalaria straminea is a freshwater snail and one of the intermediate hosts of the trematode parasite which causes schistosomiasis in Brazil. The main stages of embryonic development were analyzed with confocal laser scanning microscopy (CLSM), using the fluorescent probe DiOC and Nile Red as a vital stain in in vivo preparations. In fixed preparations nuclei were stained by the Feulgen reaction or the fluorescent DNA probe, Höechst 33342. Results obtained from the analysis of embryos at the stages of early cleavage, morula, blastula, gastrula, early trocophore and veliger showed that these stages are similar to those described for Biomphalaria glabrata and Biomphalaria tenagophila. CLSM optical sections of early trochophore showed important morphological structures such as the blastopore, stomodeum and shell gland; and in early veliger, internal organs such as the esophagus, stomach and male and female ducts were also clearly identified.     

Hybrid speciation in sparrows II: a role for sex chromosomes?

Homoploid hybrid speciation in animals is poorly understood, mainly because of the scarcity of well‐documented cases. Here, we present the results of a multilocus sequence analysis on the house sparrow (Passer domesticus), Spanish sparrow (P. hispaniolensis) and their proposed hybrid descendant, the Italian sparrow (P. italiae). The Italian sparrow is shown to be genetically intermediate between the house sparrow and Spanish sparrow, exhibiting genealogical discordance and a mosaic pattern of alleles derived from either of the putative parental species. The average variation on the Z chromosome was significantly reduced compared with autosomal variation in the putative parental species, the house sparrow and Spanish sparrow. Additionally, divergence between the two species was elevated on the Z chromosome relative to the autosomes. This pattern of variation and divergence is consistent with reduced introgression of Z‐linked genes and/or a faster‐Z effect (increased rate of adaptive divergence on the Z). F_ST‐outlier tests were consistent with the faster‐Z hypothesis: two of five Z‐linked loci (CHD1Z and PLAA) were identified as candidates for being subject to positive, divergent selection in the putative parental species. Interestingly, the two latter genes showed a mosaic pattern in the (hybrid) Italian sparrow; that is, the Italian sparrow was found to be fixed for Spanish sparrow alleles at CHD1Z and to mainly have house sparrow alleles at PLAA. Preliminary evidence presented in this study thus suggests that sex chromosomes may play a significant role in this case of homoploid hybrid speciation.     

Computational study of the conformational preferences of the (R)-8-amino-pentacyclo[5.4.0.0(2,6).0(3,10).0(5,9)]undecane-8-carboxylic acid monopeptide.

alpha-Amino acids are important building blocks for the synthesis of a large number of bioactive compounds and pharmaceutical drugs. However, a literature survey revealed that no theoretical conformational study of alpha-amino acids with cage carbon frameworks has been performed to date. This paper reports the results of a conformational study on the (R)-8-amino-pentacyclo[5.4.0.0(2,6).0(3,10).0(5,9)]undecane-8-carboxylic acid monopeptide (cage monopeptide), using molecular mechanics and ab initio methods. The in vacuo Ramachandran maps computed using the different parameterizations of the AMBER force field show the C7eq structure as the most favourable conformation, in contrast to the C7ax structure, that is the lowest energy conformation at the ab initio level. Analysis of these maps reveals the helical preference for the monopeptide and provides the potential for the cage residue to be incorporated into constrained peptide analogues.     

Human immunodeficiency virus type 1 variability and long-term non-progression.

A high heterogeneity is found in the HIV-1 genome in vivo, not only between individuals, but also within a single individual. Different types of genetic heterogeneity of HIV-1 can be analyzed: the extension and the evolution of the viral quasispecies in blood, the variation between the virus obtained from different body compartment, the differences between isolates from diverse individuals and between HIV-1 subtypes. The virus population during primary HIV-1 infection is generally homogeneous and the intrahost viral evolution is thought to be forced (in absence of antiviral therapy) by the immune system pressure and is generally related to the length of the immunocompetent period. A group of 12 Italian and Swedish well characterized HIV-1 infected long-term nonprogressors (LNTP) have been analyzed for the viral heterogeneity, calculated in the nef gene and in the long terminal repeat (LTR). The intra-sample variations in LTNP were found comparable with those from 8 progressor patients, while a lower inter-individual diversity was observed in the former. In one LTNP the viral evolution during a four-years period was extremely low suggesting that other factors than the host immune pressure may be involved in modulating the intra- and inter-sample HIV-1 diversity.     

Does seed germination contribute to ecological breadth and geographic range? A test with sympatric Diplusodon (Lythraceae) species from rupestrian fields

We tested the regeneration niche hypothesis by comparing the germination ecology of two sympatric Diplusodon species differing in their geographic range and microhabitat. Diplusodon orbicularis is an endemic shrub achieving high densities on sandy soils, whereas Diplusodon hirsutus has a wider geographic range and establishes on rocky outcrops. Seeds were set to germinate under constant temperatures of 15, 20, 25, 30 and 35°C under 12 h light/12 h dark conditions. Light induced germination in both species, but germination under darkness was also observed. Optimum conditions for germination were 25°C/light for both species. The lack of differences in soil temperatures between rocky outcrops and sandy soils provides evidence of no temperature‐dependent microhabitat selection. Unexpectedly, germinability of the more widespread species was lower than that of the endemic congener. Higher germinability of D. orbicularis may account for higher densities when compared with D. hirsutus. Our results provide limited support for the role of germination in contributing to ecological breadth and geographic range.     

Acid treatment effects on the stable isotopic signatures of fossils

Abstract: Prior to geochemical analyses, fossil bones and teeth are often extracted from any surrounding lithified sediments using chemical techniques such as immersion in acid. As stable isotope analysis becomes more commonplace in palaeoecological investigations, it is important to consider what effects these chemical preparation techniques may have on any subsequent isotopic data and to constrain these effects as quantitatively as possible. This study aims to elucidate these effects, as it is vital that variability in a data set should not be introduced as a result of protocols used during sample preparation; in addition, it defines the most effective and viable method of carbonate removal for processing bulk fossil samples without causing alteration of their stable isotopic signatures. Various strengths of two weak acids commonly used during palaeontological preparation were tested to evaluate their effects on the δ¹⁵N and δ¹³C_org isotopic signatures of the vertebrae of a large Eocene fossil fish. Changes in the isotopic values occurred over time regardless of which acid was used, each causing a variable response in both δ¹⁵N and δ¹³C_org isotopic values. Without careful monitoring of the acidification process in a controlled environment, any resulting data could therefore confound interpretation. Based on these experiments, it is recommended that 2 m acetic acid be used for the pretreatment of fossils prior to the acquisition of N and C isotope data where carbonate removal is necessary.     

Abrupt shifts in African savanna tree cover along a climatic gradient

Aim To describe patterns of tree cover in savannas over a climatic gradient and a range of spatial scales and test if there are identifiable climate‐related mean structures, if tree cover always increases with water availability and if there is a continuous trend or a stepwise trend in tree cover. Location Central Tropical Africa. Methods We compared a new analysis of satellite tree cover data with botanical, phytogeographical and environmental data. Results Along the climatic transect, six vegetation structures were distinguished according to their average tree cover, which can co‐occur as mosaics. The resulting abrupt shifts in tree cover were not correlated to any shifts in either environmental variables or in tree species distributions. Main conclusions A strong contrast appears between fine‐scale variability in tree cover and coarse‐scale structural states that are stable over several degrees of latitude. While climate parameters and species pools display a continuous evolution along the climatic gradient, these stable structural states have discontinuous transitions, resulting in regions containing mosaics of alternative stable states. Soils appear to have little effect inside the climatic stable state domains but a strong action on the location of the transitions. This indicates that savannas are patch dynamics systems, prone to feedbacks stabilizing their coarse‐scale structure over wide ranges of environmental conditions.     

Potential for carbon sequestration in European soils: preliminary estimates for five scenarios using results from long-term experiments

One of the main options for carbon mitigation identified by the IPCC is the sequestration of carbon in soils. In this paper we use statistical relationships derived from European long-term experiments to explore the potential for carbon sequestration in soils in the European Union. We examine five scenarios, namely (a) the amendment of arable soils with animal manure, (b) the amendment of arable soils with sewage sludge, (c) the incorporation of cereal straw into the soils in which it was grown, (d) the afforestation of surplus arable land through natural woodland regeneration, and (e) extensification of agriculture through ley-arable farming. Our calculations suggest only limited potential to increase soil carbon stocks over the next century by addition of animal manure, sewage sludge or straw (Þbl 15 Tg C y^–1), but greater potential through extensification of agriculture (≈ 40 Tg C y^–1) or through the afforestation of surplus arable land (≈ 50 Tg C y^–1). We estimate that extensification could increase the total soil carbon stock of the European Union by 17%. Afforestation of 30% of present arable land would increase soil carbon stocks by about 8% over a century and would substitute up to 30 Tg C y^–1 of fossil fuel carbon if the wood were used as biofuel. However, even the afforestation scenario, with the greatest potential for carbon mitigation, can sequester only 0.8% of annual global anthropogenic CO₂-carbon. Our figures suggest that, although efforts in temperate agriculture can contribute to global carbon mitigation, the potential is small compared to that available through reducing anthropogenic CO₂ emissions by halting tropical and sub-tropical deforestation or by reducing fossil fuel burning.