Ants, Cataglyphis cursor, Use Precisely Directed Rescue Behavior to Free Entrapped Relatives

Although helping behavior is ubiquitous throughout the animal kingdom, actual rescue activity is particularly rare. Nonetheless, here we report the first experimental evidence that ants, Cataglyphis cursor, use precisely directed rescue behavior to free entrapped victims; equally important, they carefully discriminate between individuals in distress, offering aid only to nestmates. Our experiments simulate a natural situation, which we often observed in the field when collecting Catagyphis ants, causing sand to collapse in the process. Using a novel experimental technique that binds victims experimentally, we observed the behavior of separate, randomly chosen groups of 5 C. cursor nestmates under one of six conditions. In five of these conditions, a test stimulus (the “victim”) was ensnared with nylon thread and held partially beneath the sand. The test stimulus was either (1) an individual from the same colony; (2) an individual from a different colony of C cursor; (3) an ant from a different ant species; (4) a common prey item; or, (5) a motionless (chilled) nestmate. In the final condition, the test stimulus (6) consisted of the empty snare apparatus. Our results demonstrate that ants are able to recognize what, exactly, holds their relative in place and direct their behavior to that object, the snare, in particular. They begin by excavating sand, which exposes the nylon snare, transporting sand away from it, and then biting at the snare itself. Snare biting, a behavior never before reported in the literature, demonstrates that rescue behavior is far more sophisticated, exact and complexly organized than the simple forms of helping behavior already known, namely limb pulling and sand digging. That is, limb pulling and sand digging could be released directly by a chemical call for help and thus result from a very simple mechanism. However, it's difficult to see how this same releasing mechanism could guide rescuers to the precise location of the nylon thread, and enable them to target their bites to the thread itself.     

Application of diffusion-edited NMR spectroscopy for the structural characterization of drug metabolites in mixtures

Diffusion-edited NMR spectroscopy is used to enable the structural characterization of low level metabolites in the presence of endogenous compounds, and organic solvents. We compared data from standard one-dimensional (1D) ¹H, 1D NOESY-presaturation, and 1D diffusion-edited experiments run on 20 μg and 100 μg samples of ethacrynic acid glutathione thioether (EASG) and a previously unreported metabolite of mefenamic acid, mefenamic acid glutathione thioester (MSG). The 1D NOESY-presaturation technique gave spectra with the best signal-to-noise (S/N) ratio, approximately three times that observed with the standard ¹H experiment, with respect to the metabolite signals. However, it was not selective for solvent signals as overlapping metabolite signals were also suppressed by this technique. In some cases, these signals were key to determining the site of glutathione attachment on the parent molecule. 1D NOESY-presaturation spectra also produced baseline distortions and inconsistent integration values. By comparison, 1D diffusion-edited experiments were found to selectively and simultaneously remove multiple solvent signals, resolve overlapping metabolite signals, and provide more uniform integration for metabolite signals overlapping with or proximal to solvent peaks, without producing baseline distortions. However, the diffusion-edited experiments caused significant signal attenuation of the metabolite signals when compared with a standard ¹H spectrum. Partially purified metabolites isolated from biological matrices were also characterized by using two-dimensional diffusion-ordered spectroscopy (DOSY). DOSY spectra acquired on a sample of EASG purified from rat bile proved useful in ‘separating’ the signals of EASG, from those of a co-eluting bile acid and parent drug ethacrynic acid (EA) in the diffusion-dimension in regions where there was no spectral overlap. In the low-field regions of high overlap, the DOSY experiment did not effectively separate the signals from the individual components. Diffusion based experiments provide a way to determine the total number of components that are present in a metabolite sample as well as an ability to identify them based on the chemical shift information, without the need for laborious chromatography on small samples.     

Pharyngo-oesophageal haemangioma with a positive cough impulse.

Benign tumours of both the pharynx and oesophagus are rarely seen, cavernous haemangiomas even less so. We present a case in which a large lesion was the cause of non-specific symptoms but which only appeared intermittently on nasendoscopic examination of the pharynx.     

The RNA binding protein CPEB regulates dendrite morphogenesis and neuronal circuit assembly in vivo

Visual system development requires experience-dependent mechanisms that regulate neuronal structure and function, including dendritic arbor growth, synapse formation, and stabilization. Although RNA binding proteins have been shown to affect some forms of synaptic plasticity in adult animals, their role in the development of neuronal structure and functional circuitry is not clear. Using two-photon time-lapse in vivo imaging and electrophysiology combined with morpholino-mediated knockdown and expression of functional deletion mutants, we demonstrate that the mRNA binding protein, cytoplasmic polyadenylation element binding protein1 (CPEB1), affects experience-dependent neuronal development and circuit formation in the visual system of Xenopus laevis. These data indicate that sensory experience controls circuit development by regulating translational activity of mRNAs.     

Trauma audit: clinical judgement or statistical analysis?

Comparisons have been made between two methods currently used to assess the effectiveness of management of major trauma. These are the review of fatal cases by senior clinicians and the use of statistical analysis of severity scores. The former was assessed by a re-examination of the Coroners' reports of 508 patients reviewed by senior clinicians at the request of The Royal College of Surgeons of England Working Party on the Management of Patients with Major Injuries. The latter was based on the 665 fatalities on the files of the UK Major Trauma Outcome Study. The two groups of patients had comparable age and sex profiles and broadly similar ranges of injury severity. There were major differences between and inconsistencies within the two assessments. Clinicians more frequently judged death avoidable in those with very severe injuries. In contrast, the statistical analysis suggested, paradoxically, that the proportion of avoidable deaths in those patients who had minor injuries was less than the proportion of avoidable deaths in those who had more serious injuries. These variations underline the limited values of retrospective peer review and will not encourage clinicians to adopt currently available statistical methods. Further refinements of anatomical and physiological scoring systems and their integration to provide a statistically valid and clinically acceptable measure of outcome are essential prerequisites to the wider introduction and success of trauma audit.     

Sustained pressurization of polymethylmethacrylate: a comparison of low- and moderate-viscosity bone cements

There is at present great uncertainty relating to the fixation of joint implants. The deficiencies of acrylic bone cement are well documented, but the limitations of cementless fixation are as yet imcompletely identified. The purpose of this study was to investigate the potential of sustained external pressurization to improve the mechanical characteristics of conventional acrylic bone cement. The effect of serially increasing sustained pressurization of two commerically available acrylic bone cements (Simplex-P and LVC) was evaluated in human cadaver femora. A new method for determination of the shear strength of the bone-cement interface in place of the traditional pushout tests was used. In this model, there was a significant increase in the bone-cement interfacial shear strength with increasing pressure, but no difference in the shear strength was found between the two cements. At all pressure levels, the shear strength of the cement was greater than that previously reported. Increased cement penetration into the cortical bone was demonstrated with increasing pressure and low-viscosity cement, but the extent of cement penetration did not correlate with the shear strength of the bone-cement interface.