A straightjacket for pain?

Perception of pain involves both the peripheral and central nervous systems. Starting with a whole-genome RNA interference screen in Drosophila, Neely et?al. (2010) identify a mammalian gene that is required not only for efficient transfer of pain signals between brain centers, but also for the suppression of inappropriate signaling between other sensory systems.     

A need for niches?

The idea that different species must have distinct ecologies if they are to coexist has been challenged recently by the claim that some models involving stochastic factors or clumped spatial distributions permit stable coexistence of species that are identical or differ only in competitive ability. However, these models have been misinterpreted; except in rather limited circumstances, they provide further support for the notion that species must be sufficiently ecologically distinct to coexist stably. The possible, limited, exceptions to this rule involve social factors by which individuals of a species discriminate between heterospecifics and conspecifics without there being any true ecological differences between species.     

A regimen for low-dose aspirin?

The effects of different regimens of 40 mg aspirin on platelet thromboxane A2 synthesis and vascular prostacyclin synthesis were determined in patients who were undergoing elective surgery for removal of varicose veins. Aspirin 40 mg taken at intervals of 48 hours consistently reduced platelet thromboxane A2 synthesis to a level at which it failed to support platelet aggregation and the associated release reaction. This effect lasted for at least 36 hours. In contrast, aspirin 40 mg every 72 hours did not have the same consistent effect. Both dose regimens led to a reduction in vascular prostacyclin synthesis 12 hours after the last dose, but 36 or 72 hours after the last dose prostacyclin synthesis was not reduced; thus the inhibition of prostacyclin synthesis was short lived. If the balance between platelet thromboxane A2 and vascular prostacyclin synthesis is important in thrombosis 40 mg aspirin every 48 hours may have the maximum antithrombotic effect.     

Terminology—A plea for consistency

Editorial

Terminology—A plea for consistency     

A biogeochemical cycle for aluminium?

The elaboration of biogeochemical cycles for elements which are known to be essential for life has enabled a broad appreciation of the homeostatic mechanisms which underlie element essentiality. In particular they can be used effectively to identify any part played by human activities in element cycling and to predict how such activities might impact upon the lithospheric and biospheric availability of an element in the future. The same criteria were the driving force behind the construction of a biogeochemical cycle for aluminium, a non-essential element which is a known ecotoxicant and a suspected health risk in humans. The purpose of this exercise was to examine the concept of a biogeochemical cycle for aluminium and not to review the biogeochemistry of this element. The cycle as presented is rudimentary and qualitative though, even in this nascent form, it is informative and predictive and, for these reasons alone, it is deserving of future quantification. A fully fledged biogeochemical cycle for aluminium should explain the biospheric abundance of this element and whether we should expect its (continued) active involvement in biochemical evolution.     

A mitotic function for Src?

During mitosis, the activity of the c-Src protein tyrosine kinase increases. The tyrosine phosphorylation of a 68 kDa protein (Sam68) also increases at this time, and recent studies have shown that Src and Sam68 interact. Sam68 is highly related to p62, a RasGAP-associated protein, and has homology to RNA-binding proteins. The relationship between p62 and Sam68, and their roles in Src signalling, need to be clarified, but these findings suggest that Src may participate in regulating RNA processing during the cell cycle.     

A model for gramicidin A′-phospholipid interactions in bilayers

A model is proposed for the effect of gramicidin A on the order and structure of phospholipid dispersions. According to this model, the addition of gramicidin A influences the surrounding lipids via two independent mechanisms. The first arises from a drop in surface pressure for those lipids substantially bounded by gramicidin A. The second mechanism arises from the increase in the phospholipid headgroup spacing due to the small polar region of the polypeptide. The model provides an explanation for the currently available NMR, X-ray diffraction and Langmuir monolayer results. The model also suggests mechanisms for the ability of gramicidin A to trigger a transition of the lipid from the lamellar to hexagonal II phase, the dependence of this transition on the lipid chain length and the formation of a lamellar phase with lysophosphatidylcholine.Abbreviations NMR nuclear magnetic resonance - DMPC dimyristoylphosphatidylcholine - S molecular order parameter - CSA chemical shift anisotropy - DPPC dipalmitoylphosphati-dylcholine - LPC lysophosphatidylcholine     

A brief method for analyzing Rotorod® samples for pollen content

Analyzing Rotorod^® pollen samples can be time consuming when one uses the standard method of evaluating an entire collector rod. This present investigation explored an abbreviated analysis method which is indicated by Poisson statistical theory. The authors systematically analyzed 18 Rotorod pollen samples from Spring 1994 which contained 408–7394 pollen grains per rod. The atmospheric pollen concentration (pollen grains/m³) was calculated from the number of pollen grains contained on the entire rod surface (P_total) and a sub-area containing at least 400 grains (P_>400). The estimate of the atmospheric pollen concentration resulting from P_total and P_>400 for each rod did not vary by more than ±9% (mean, 2.0%±3.7). These data indicate that pollen grains populated the sample rods rather uniformly, suggesting a mode of random recovery from the atmosphere. This study's results are consistent with the expectations concerning a Poisson process and support analyzing collector rods until a threshold number of pollen grains is counted.     

A dry lab for medical engineers?

Post-operatory wound infections are a very uncommon finding after thyroidectomy. For these reasons international guidelines do not routinely recommend systemic antibiotic prophylaxis. The benefits of this antibiotic prophylaxis is not supported by clinical evidence in the literature. We have conducted a multicentric randomized double-blind trial on 500 patients who had undergone thyroidectomy for goitre or thyroid carcinoma. The 500 patients enrolled in the study (mean age 47 years) were randomized in two subgroups of 250 patients. 250 patients were treated with standard antibiotic prophylaxis with sulbactam/ampicillin 1 fl (3 gr.) 30 min before surgery. No antibiotic prophylaxis was instituted in the remainder 250 patients. Our RCT showed that prophylactic antibiotic treatment is not beneficial in patients younger than eighty years old, with no concomitant metabolic, infective and hematologic disease, with no cardiac valvulopathies, not under steroidal or immunosuppressive treatment, and not severely obese. Our study should be regarded only as a preliminary RCT, and should be followed by a study in which a larger number of patients should be enrolled so that statistically significant data can be obtained.     

A neuropeptide courier for delta-opioid receptors?

The delta-opioid receptor and the precursor protein of a neuropeptide, substance P, are colocalized in the large dense-core vesicles of pain-sensing neurons. In this issue of Cell, report that trafficking of the delta-opioid receptor to these vesicles depends on its physical interaction with the substance P domain of its precursor polyprotein (protachykinin). Moreover, in mice lacking this precursor, the contribution of the delta-opioid receptor to pain processing is dramatically altered. These observations suggest a new role for peptide precursors as sorting signals in vesicular transport.