Acetylcholine synthesis and neuron differentiation

Development of the nervous system is dependent on the co-operation between cell determination events and the action of epigenetic factors; in addition to well known factors, e.g. growth factors, neurotransmitters have been assigned a role as "morphogens" and modulators of neuronal differentiation in an early developmental phase. The possible role of acetylcholine as a modulator of neuronal differentiation has been considered in two experimental systems. A neuroblastoma cell line, which does not synthesise any neurotransmitter, has been transfected with a choline acetyltransferase construct; activation of acetylcholine synthesis, thus achieved, is followed by a higher expression of neuronal specific traits. The presence in these cells of muscarinic receptors is consistent with the existence of an autocrine loop, which may be responsible for the more advanced differentiation state observed in the transfected cells. Expression of cholinergic markers appears as a common feature of DRG sensory neurons, independently of the neurotransmitter used. Choline acetyltransferase can be detected in DRG at early developmental stages. The distribution of muscarinic receptors in DRG has suggested that activation of acetylcholine synthesis may be related in an early developmental phase to the interaction between neurons and nonneuronal cells and to modulation of cell differentiation. Both systems suggest that acetylcholine may have a role as a modulator of neuronal differentiation.     

Copper-adapted Suillus luteus, a symbiotic solution for pines colonizing Cu mine spoils

Natural populations thriving in heavy-metal-contaminated ecosystems are often subjected to selective pressures for increased resistance to toxic metals. In the present study we describe a population of the ectomycorrhizal fungus Suillus luteus that colonized a toxic Cu mine spoil in Norway. We hypothesized that this population had developed adaptive Cu tolerance and was able to protect pine trees against Cu toxicity. We also tested for the existence of cotolerance to Cu and Zn in S. luteus. Isolates from Cu-polluted, Zn-polluted, and nonpolluted sites were grown in vitro on Cu- or Zn-supplemented medium. The Cu mine isolates exhibited high Cu tolerance, whereas the Zn-tolerant isolates were shown to be Cu sensitive, and vice versa. This indicates the evolution of metal-specific tolerance mechanisms is strongly triggered by the pollution in the local environment. Cotolerance does not occur in the S. luteus isolates studied. In a dose-response experiment, the Cu sensitivity of nonmycorrhizal Pinus sylvestris seedlings was compared to the sensitivity of mycorrhizal seedlings colonized either by a Cu-sensitive or Cu-tolerant S. luteus isolate. In nonmycorrhizal plants and plants colonized by the Cu-sensitive isolate, root growth and nutrient uptake were strongly inhibited under Cu stress conditions. In contrast, plants colonized by the Cu-tolerant isolate were hardly affected. The Cu-adapted S. luteus isolate provided excellent insurance against Cu toxicity in pine seedlings exposed to elevated Cu levels. Such a metal-adapted Suillus-Pinus combination might be suitable for large-scale land reclamation at phytotoxic metalliferous and industrial sites.     

Engineered endophytic bacteria improve phytoremediation of water-soluble, volatile, organic pollutants

Phytoremediation of highly water soluble and volatile organic xenobiotics is often inefficient because plants do not completely degrade these compounds through their rhizospheres. This results in phytotoxicity and/or volatilization of chemicals through the leaves, which can cause additional environmental problems. We demonstrate that endophytic bacteria equipped with the appropriate degradation pathway improve the in planta degradation of toluene. We introduced the pTOM toluene-degradation plasmid of Burkholderia cepacia G4 into B. cepacia L.S.2.4, a natural endophyte of yellow lupine. After surface-sterilized lupine seeds were successfully inoculated with the recombinant strain, the engineered endophytic bacteria strongly degraded toluene, resulting in a marked decrease in its phytotoxicity, and a 50-70% reduction of its evapotranspiration through the leaves. This strategy promises to improve the efficiency of phytoremediating volatile organic contaminants.     

High-Resolution Postcontrast Time-of-Flight MR Angiography of Intracranial Perforators at 7.0 Tesla

Background and Purpose

Different studies already demonstrated the benefits of 7T for precontrast TOF-MRA in the visualization of intracranial small vessels. The aim of this study was to assess the performance of high-resolution 7T TOF-MRA after the administration of a gadolinium-based contrast agent in visualizing intracranial perforating arteries.

Materials and Methods

Ten consecutive patients (7 male; mean age, 50.4 ± 9.9 years) who received TOF-MRA at 7T after contrast administration were retrospectively included in this study. Intracranial perforating arteries, branching from the parent arteries of the circle of Willis, were identified on all TOF-MRA images. Provided a TOF-MRA before contrast administration was present, a direct comparison between pre- and postcontrast TOF-MRA was made.

Results

It was possible to visualize intracranial perforating arteries branching off from the entire circle of Willis, and their proximal branches. The posterior cerebral artery (P1 and proximal segment of P2) appeared to have the largest number of visible perforating branches (mean of 5.1 in each patient, with a range of 2–7). The basilar artery and middle cerebral artery (M1 and proximal segment M2) followed with a mean number of 5.0 and 3.5 visible perforating branches (range of 1–9 and 1–8, respectively). Venous contamination in the postcontrast scans sometimes made it difficult to discern the arterial or venous nature of a vessel.

Conclusion

High-resolution postcontrast TOF-MRA at 7T was able to visualize multiple intracranial perforators branching off from various parts of the circle of Willis and proximal intracranial arteries. Although confirmation in a larger study is needed, the administration of a contrast agent for high-resolution TOF-MRA at 7T seems to enable a better visualization of the distal segment of certain intracranial perforators.     

Counterintuitive DNA Sequence Dependence in Supercoiling-Induced DNA Melting

The metabolism of DNA in cells relies on the balance between hybridized double-stranded DNA (dsDNA) and local de-hybridized regions of ssDNA that provide access to binding proteins. Traditional melting experiments, in which short pieces of dsDNA are heated up until the point of melting into ssDNA, have determined that AT-rich sequences have a lower binding energy than GC-rich sequences. In cells, however, the double-stranded backbone of DNA is destabilized by negative supercoiling, and not by temperature. To investigate what the effect of GC content is on DNA melting induced by negative supercoiling, we studied DNA molecules with a GC content ranging from 38% to 77%, using single-molecule magnetic tweezer measurements in which the length of a single DNA molecule is measured as a function of applied stretching force and supercoiling density. At low force (<0.5pN), supercoiling results into twisting of the dsDNA backbone and loop formation (plectonemes), without inducing any DNA melting. This process was not influenced by the DNA sequence. When negative supercoiling is introduced at increasing force, local melting of DNA is introduced. We measured for the different DNA molecules a characteristic force F _char, at which negative supercoiling induces local melting of the dsDNA. Surprisingly, GC-rich sequences melt at lower forces than AT-rich sequences: F _char = 0.56pN for 77% GC but 0.73pN for 38% GC. An explanation for this counterintuitive effect is provided by the realization that supercoiling densities of a few percent only induce melting of a few percent of the base pairs. As a consequence, denaturation bubbles occur in local AT-rich regions and the sequence-dependent effect arises from an increased DNA bending/torsional energy associated with the plectonemes. This new insight indicates that an increased GC-content adjacent to AT-rich DNA regions will enhance local opening of the double-stranded DNA helix.     

Use of Occult Blood Detection Cards for Real-Time PCR-Based Diagnosis of Schistosoma Mansoni Infection

Background

In Schistosoma mansoni infection, diagnosis and control after treatment mainly rely on parasitological stool investigations which are laborious and have limited sensitivity. PCR methods have shown equal or superior sensitivity but preservation and storage methods limit their use in the field. Therefore, the use of occult blood detection cards (fecal cards) for easy sampling and storage of fecal samples for further PCR testing was evaluated in a pilot study.

Methodology

Stool specimens were collected in a highly endemic area for S. mansoni in Ethiopia and submitted in an investigator-blinded fashion to microscopic examination by Kato-Katz thick smear as well as to real-time PCR using either fresh frozen stool samples or stool smears on fecal cards which have been stored at ambient temperature for up to ten months.

Principal Findings

Out of 55 stool samples, 35 were positive by microscopy, 33 and 32 were positive by PCR of frozen samples and of fecal card samples, respectively. When microscopy was used as diagnostic “gold standard”, the sensitivity of PCR on fresh stool was 94.3% (95%-CI: 86.6; 100) and on fecal cards 91.4% (95%-CI: 82.2; 100).

Conclusions

The use of fecal cards proved to be a simple and useful method for stool collection and prolonged storage prior to PCR based diagnosis of S. mansoni infection. This technique may be a valuable approach for large scale surveillance and post treatment assessments     

Characterization of the cultivable bacterial populations associated with field grown Brassica napus L.: an evaluation of sampling and isolation protocols

Plant‐associated bacteria are intensively investigated concerning their characteristics for plant growth promotion, biocontrol mechanisms and enhanced phytoremediation efficiency. To obtain endophytes, different sampling and isolation protocols are used although their representativeness is not always clearly demonstrated. The objective of this study was to acquire representative pictures of the cultivable bacterial root, stem and leaf communities for all Brassica napus L. individuals growing on the same field. For each plant organ, genotypic identifications of the endophytic communities were performed using three replicates. Root replicates were composed of three total root systems, whereas stem and leaf replicates needed to consist of six independent plant parts in order to be representative. Greater variations between replicates were found when considering phenotypic characteristics. Correspondence analysis revealed reliable phenotypic results for roots and even shoots, but less reliable ones for leaves. Additionally, realistic Shannon–Wiener biodiversity indices were calculated for all three organs and showed similar Evenness factors. Furthermore, it was striking that all replicates and thus the whole plant contained Pseudomonas and Bacillus strains although aboveground and belowground plant tissues differed in most dominant bacterial genera and characteristics.     

Psychiatric discharge summaries: what do general practitioners want?

Aims As part of an initiative to improve and standardise our discharge summaries, we investigated the preferences of general practitioners (GPs) with regards to the information provided in summaries.Method Our study methods included sending a questionnaire to all GPs in our area gathering their views on what information to include in discharge summaries on first and on subsequent inpatient episodes.Results The response rate was 68%. Most GPs wanted a comprehensive first discharge summary, particularly stressing the importance of practical information. Subsequent discharge summaries could exclude case histories.Clinical implications Contrary to previous studies indicating a demand for brief reports, this survey indicates that the GPs surveyed value considerable detail in adult psychiatry discharge summaries. It is important to include these views in setting standards for the auditing process and before implementing changes.     

An epidemiological reappraisal of the familial aggregation of prostate cancer: a meta-analysis

Studies on familial aggregation of cancer may suggest an overall contribution of inherited genes or a shared environment in the development of malignant disease. We performed a meta-analysis on familial clustering of prostate cancer. Out of 74 studies reporting data on familial aggregation of prostate cancer in unselected populations retrieved by a Pubmed search and browsing references, 33 independent studies meeting the inclusion criteria were used in the analysis performed with the random effects model. The pooled rate ratio (RR) for first-degree family history, i.e. affected father or brother, is 2.48 (95% confidence interval: 2.25–2.74). The incidence rate for men who have a brother who got prostate cancer increases 3.14 times (CI:2.37–4.15), and for those with affected father 2.35 times (CI:2.02–2.72). The pooled estimate of RR for two or more affected first-degree family members relative to no history in father and in brother is 4.39 (CI:2.61–7.39). First-degree family history appears to increase the incidence rate of prostate cancer more in men under 65 (RR:2.87, CI:2.21–3.74), than in men aged 65 and older (RR:1.92, CI:1.49–2.47), p for interaction = 0.002. The attributable fraction among those having an affected first-degree relative equals to 59.7% (CI:55.6–63.5%) for men at all ages, 65.2% (CI:57.7–71.4%) for men younger than 65 and 47.9% (CI:37.1–56.8%) for men aged 65 or older. For those with a family history in 2 or more first-degree family members 77.2% (CI:65.4–85.0%) of prostate cancer incidence can be attributed to the familial clustering. Our combined estimates show strong familial clustering and a significant effect-modification by age meaning that familial aggregation was associated with earlier disease onset (before age 65).     

Mother Knows Best: Occurrence and Associations of Resighted Humpback Whales Suggest Maternally Derived Fidelity to a Southern Hemisphere Coastal Feeding Ground

Site fidelity is common among migratory cetaceans, including humpback whales (Megaptera novaeangliae). In the Northern Hemisphere it has been found that fidelity to humpback whale feeding grounds is transferred maternally but this has never been shown for the species in the Southern Hemisphere. We examined this in a unique feeding area off west South Africa using resighting data of 68 individually identified humpback whales by means of photographic (tail flukes and dorsal fins) and/or molecular methods (microsatellite genotyping) over an 18 year span. We found short-term association patterns and recurrent visits typical of other feeding grounds. Males and females had different seasonality of attendance. Significant female-dominated presence corresponded to timing of an expected influx of females on their southward migration from the breeding ground: firstly non-nursing (possibly pregnant) females in mid-spring, and mothers and calves in mid-to late summer. The potential benefit of this mid-latitude feeding area for females is illustrated by a record of a cow with known age of at least 23 years that produced calves in three consecutive years, each of which survived to at least six months of age: the first record of successful post-partum ovulation for this species in the Southern Hemisphere. We recorded association of a weaned calf with its mother, and a recurring association between a non-lactating female and male over more than two years. Moreover, three animals first identified as calves returned to the same area in subsequent years, sometimes on the same day as their mothers. This, together with numerous Parent-Offspring relations detected genetically among and between resighted and non-resighted whales is strongly suggestive of maternally derived site fidelity at a small spatial scale by a small sub-population of humpback whales.