A randomised, blinded, crossover study to assess the efficacy of a feed supplement in alleviating the clinical signs of headshaking in 32 horses.

REASONS FOR PERFORMING STUDY: Feed supplements are commonly used by owners to alleviate headshaking; however, randomised, controlled trials are required to assess their efficacy. OBJECTIVE: To determine the efficacy of a feed supplement for alleviation of the clinical signs of headshaking using a randomised, blinded, placebo-controlled trial. METHODS: Using a crossover design, 44 horses previously diagnosed with chronic idiopathic headshaking received both the supplement and a matching placebo per os for 28 days with a washout period between of 14 days. Video recordings were taken at rest and exercise prior to the study and at the end of both periods of treatment. The degree of headshaking was assessed in a blinded, randomised manner by 2 veterinary surgeons. At the same time points, owners completed a questionnaire to assess the severity of headshaking signs. A Wilcoxon signed rank test was used to compare the scores while on supplement and placebo. RESULTS: Using the video assessments, there was no significant difference between scores while on supplement compared with placebo (P = 0.7). Using the questionnaire responses, there was no significant difference between scores for any activity when the placebo and the supplement were compared with each other. However, owners reported significant improvement during all activities for both placebo and supplement compared with pretreatment scores. CONCLUSIONS AND POTENTIAL RELEVANCE: The supplement offered no benefit over a placebo in alleviating the clinical signs of headshaking. There appeared to be a significant proxy placebo effect when the outcome was based on subjective owner perception of clinical signs. This study demonstrated no beneficial effect of this supplement on the clinical signs of headshaking. The study did show a significant placebo effect, thereby highlighting the necessity of properly conducted, randomised controlled trials, with blinding, to assess true treatment effects in trials in animals.

Herniation of the lung after video-assisted thoracic surgery.

We report a case of lung herniation occurring following video-assisted thoracic surgery. Although lung hernias are rare, the widespread application of video-assisted thoracic surgery to patients at risk for lung hernia will likely result in more reports in the future. Consequently, pulmonologists and thoracic surgeons must be aware of this condition, risk factors for development, and potential methods of prevention in order to minimize the occurrence of this complication.

Sequestration of the lung arising from the circumflex coronary artery.

Sequestration is an unusual pulmonary malformation. Systemic blood supply is commonly from the thoracic aorta, but arteries may occasionally arise from other sites including the abdominal aorta or the intercostal vessels. We report a rare form of sequestration with origin from the circumflex coronary artery. Knowledge of uncommon vascular origins, particularly from coronary arteries, is important to avoid injury and possible ischemia, infarction, exsanguination, or death.

Acyl chain unsaturation and vesicle curvature alter outer leaflet packing and promote poly(ethylene glycol)-mediated membrane fusion.

The poly(ethylene glycol) (PEG)-induced fusion of sonicated, unilamellar vesicles (SUV) and large, unilamellar vesicles (LUV) composed of a variety of phosphatidylcholine species was compared using two assays for the mixing and leakage of internal vesicle contents. In the first [Lentz et al. (1992) Biochemistry, 31, 2643], disodium 8-aminonaphthalene-1,3,6-trisulfonate (ANTS) fluorescence is quenched by co-encapsulated N,N'-p-xylylenebis(pyridinium bromide) (DPX). For this assay, interference by the fluorescence of impurities in PEG demands that the PEG content of the sample be reduced by dilution before measurements are taken. The second assay [Viguera et al. (1993) Biochemistry, 32, 3708] monitors the fluorescence of Tb3+ complexed with dipicolinic acid (DPA) directly in concentrated PEG solutions. The two assays gave identical fusion profiles for egg PC SUVs treated with increasing concentrations of PEG, demonstrating that fusion occurs in the dehydrated state in the presence of PEG and does not require dilution. Comparison of results obtained with lipid species of varying degrees of unsaturation incorporated into either SUV or LUV suggested that acyl chain unsaturation and high membrane curvature combine to favor fusion of pure phosphatidylcholine membranes. There was a clear correlation between the fluorescence lifetime or the order parameter of the membrane probe 1-(4-trimethylammonium)-6-phenyl-1,3,5-hexatriene (TMA-DPH) in different membranes and the concentration of PEG needed to induce fusion of these membranes. However, the ratios of TMA-DPH lifetimes measured in D2O versus H2O buffers were the same for different lipid species, indicating that probe penetration was not very different for different lipid species. The results suggest that the combined effect of high membrane curvature and extensive chain unsaturation is an enhanced rate of lipid motion in the upper region of the bilayer, reflective of decreased packing density in the outer leaflet of unsaturated SUV bilayers, probably allowing for enhanced water penetration leading to an enhanced probability of fusion.

Elastic compression in the prevention of venous stasis. A critical reevaluation.

The effect of elastic compression on venous flow in the legs provided by carefully fitted stockings has been measured by a venographic technic. The stocking used provides a gradually decreasing compression from ankle to groin. Clearance of stagnant blood from behind venous valves is clearly improved and the differences observed are statistically highly significant. These data suggest that the routine use of carefully fitted compression stockings will result in a decreased incidence of deep vein thrombosis (DVT) and provide a singularly safe, convenient, and noninvasive method of prophylaxis. Evidence presented suggests that at least two investigators have failed to show a decreased incidence of DVT in limbs subjected to elastic compression because the method of compression was inadequate .