Complementary and alternative treatments for migraine

Patients love complementary and alternative treatments! Most colleagues spend a significant amount of time discussing the benefit and the risk of these therapies. Fortunately, there is scientific evidence for or against the efficacy of several such therapeutic approaches. Knowing the evidence helps to facilitate the therapeutic process, especially when dealing with patients with chronic headache. Behavioral approaches, such as cognitive behavior therapy, relaxation techniques, and biofeedback, are supported by evidence (which is partly outdated), but require a significant amount of time. Physiotherapy and aerobic exercise may be effective to treat headaches and interestingly, the latter also seems to work in depression. The evidence for hypnosis is lacking, possibly for methodological reasons. Homeopathy was shown not to be effective in headaches. There is no convincing evidence for the efficacy of spinal manipulation. There is growing evidence that acupuncture is efficacious; however, there seems to be no difference to sham acupuncture. For several vitamins and supplements, as well as herbal remedies, there is evidence from small, randomized controlled trials. A major problem is that traditional and statistically powerful trial designs cannot be applied in quite a number of complementary and alternative treatments. The best way to treat patients with headache is most probably a tailored approach with a combination of both, conventional and complementary treatment, resulting in a multimodal migraine management.     

Congruency of scapula locking plates: implications for implant design

We conducted a study to evaluate the congruency of fit of current scapular plate designs. Three-dimensional image-processing and -analysis software, and computed tomography scans of 12 cadaveric scapulae were used to generate 3 measurements: mean distance from plate to bone, maximum distance, and percentage of plate surface within 2 mm of bone. These measurements were used to quantify congruency. The scapular spine plate had the most congruent fit in all 3 measured variables. The lateral border and glenoid plates performed statistically as well as the scapular spine plate in at least 1 of the measured variables. The medial border plate had the least optimal measurements in all 3 variables. With locking-plate technology used in a wide variety of anatomical locations, the locking scapula plate system can allow for a fixed-angle construct in this region. Our study results showed that the scapular spine, glenoid, and lateral border plates are adequate in terms of congruency. However, design improvements may be necessary for the medial border plate. In addition, we describe a novel method for quantifying hardware congruency, a method that can be applied to any anatomical location.     

Production of extremely low volatile organic compounds from biogenic emissions: Measured yields and atmospheric implications

Oxidation products of monoterpenes and isoprene have a major influence on the global secondary organic aerosol (SOA) burden and the production of atmospheric nanoparticles and cloud condensation nuclei (CCN). Here, we investigate the formation of extremely low volatility organic compounds (ELVOC) from O₃ and OH radical oxidation of several monoterpenes and isoprene in a series of laboratory experiments. We show that ELVOC from all precursors are formed within the first minute after the initial attack of an oxidant. We demonstrate that under atmospherically relevant concentrations, species with an endocyclic double bond efficiently produce ELVOC from ozonolysis, whereas the yields from OH radical-initiated reactions are smaller. If the double bond is exocyclic or the compound itself is acyclic, ozonolysis produces less ELVOC and the role of the OH radical-initiated ELVOC formation is increased. Isoprene oxidation produces marginal quantities of ELVOC regardless of the oxidant. Implementing our laboratory findings into a global modeling framework shows that biogenic SOA formation in general, and ELVOC in particular, play crucial roles in atmospheric CCN production. Monoterpene oxidation products enhance atmospheric new particle formation and growth in most continental regions, thereby increasing CCN concentrations, especially at high values of cloud supersaturation. Isoprene-derived SOA tends to suppress atmospheric new particle formation, yet it assists the growth of sub-CCN-size primary particles to CCN. Taking into account compound specific monoterpene emissions has a moderate effect on the modeled global CCN budget.Formation and subsequent growth of new aerosol particles is a major source of cloud condensation nuclei (CCN) in the global troposphere (1, 2), and a big contributor to the large reported uncertainty in the radiative forcing by aerosol−cloud interactions (3–7). Multiple field studies have shown that CCN production is tightly connected with the oxidation of biogenic volatile organic compounds (BVOC) emitted by terrestrial ecosystems (8–11). To explain these observations, large-scale model simulations demonstrate a need for a BVOC oxidation mechanism in the atmosphere that produces very low volatility organic vapors with molar formation yields of at least a few percent per reacted precursor compound (12–14).The existence and formation mechanisms of essentially nonvolatile organic vapors in the atmosphere have puzzled scientists for some time (14–16). Such extremely low volatile organic compounds (ELVOC) (17) were recently detected, both in laboratory studies and in the ambient atmosphere (18), yet typical atmospheric oxidation chemistry schemes do not explain ELVOC produced on a time scale of minutes or hours. Furthermore, current state-of-the-art models using available chemistry schemes have systematically failed to reproduce the observed concentrations and volatility of organic aerosol components (17, 19). A plausible explanation for the fast ELVOC production was recently given by Ehn et al. (20), who proposed that highly oxidized (O:C ≈ 1) ELVOC are formed as first-generation oxidation products of α-pinene, a monoterpene emitted in vast quantities by different ecosystems. The authors proposed that α-pinene oxidation by ozone (O₃) forms peroxy radicals (RO₂), which undergo successive intramolecular hydrogen shifts followed by a rapid reaction with O₂, resulting in prompt production of high levels of oxygenation. This formation pathway, leading to highly oxygenated RO₂ radical and ELVOC formation, was more recently confirmed by Jokinen et al. (21) and Rissanen et al. (22). They showed that autoxidation, a mechanism known to be important in the liquid phase and which has been hypothesized to take place also in the gas phase (23), could mechanistically explain the gas-phase ELVOC formation. Their results also unambiguously demonstrated that highly oxidized RO₂ radicals and closed-shell ELVOC monomers (with a C₁₀ carbon skeleton) and dimers (C₂₀ carbon skeleton) are formed on time scales of seconds, thereby indicating immediate production of condensable vapors close to emission sources.Surprisingly, according to Ehn et al. (20), α-pinene appears to produce ELVOC with a much higher molar yield from ozonolysis (∼7%) than from the OH radical reaction (<1%). Jokinen et al. (21) investigated the relative importance of O₃ and OH radicals in the formation of highly oxygenated RO₂ from limonene and α-pinene, both having a reactive endocyclic double bond. They found that the amount of highly oxidized RO₂ radicals formed from the OH radical oxidation was only a small fraction of that from the pure ozonolysis reaction. The observed ELVOC yield from β-pinene ozonolysis in Ehn et al. (20) was much lower than that from α-pinene ozonolysis, indicating that the results obtained for α-pinene and limonene cannot be generalized to all BVOC, or even to all monoterpenes, present in the atmosphere. The relative yields of ELVOC and more volatile oxidized organics are key parameters for both regional and global CCN budgets, as their influence on atmospheric new particle formation as well as growth of both newly formed particles and sub-CCN-size primary particles can be markedly different (e.g., refs. 3 and 12).The mixture of BVOC emitted to the atmosphere contains a large number of compounds with different chemical structures (24). The magnitude and variability of these emissions are, however, not well understood. Even in the boreal forest, composed of only a few dominant tree species, BVOC emission patterns are complex, with prominent seasonal cycles (25) and large differences even between individual trees of the same species (26). In the tropics, with more diverse vegetation properties, relatively few BVOC emission assessments have been published so far (e.g., refs. 27 and 28). Future BVOC emission characteristics are expected to change considerably in many regions as a result of increasing temperatures and CO₂ concentrations, as well as changes in extreme weather conditions and vegetation cover (25, 29–31).In this work, we investigate ELVOC formation and associated CCN production from BVOC species having different chemical structures. We determine ELVOC yields from both ozonolysis and OH radical-initiated oxidation of five major BVOC species through comprehensive laboratory experiments. These species include monoterpenes with endocyclic and exocyclic double bonds and acyclic compounds with reactive double bonds (hereafter referred as endocyclic, exocyclic, and acyclic terpenes) as well as isoprene. Based on the observed ELVOC yields, we then use global model simulations to investigate the implications of our findings on atmospheric CCN production.