Rumination syndrome: Assessment of vagal tone during and after meals and during diaphragmatic breathing

Background: Pathophysiology of rumination syndrome (RS) is not well understood. Treatment with diaphragmatic breathing improves rumination syndrome. The aim of the study was to characterize vagal tone in patients with rumination syndrome during and after meals and during diaphragmatic breathing. Methods: We prospectively recruited 10 healthy volunteers (HV) and 10 patients with RS. Subjects underwent measurement of vagal tone using heart rate variability. Vagal tone was measured during baseline, test meal and intervention (diaphragmatic (DiaB), slow deep (SlowDB), and normal breathing). Vagal tone was assessed using mean values of root mean square of successive differences (RMSSD), and area under curves (AUC) were calculated for each period. We compared baseline RMSSD, the AUC and meal‐induced discomfort scores between HV and RS. Furthermore, we assessed the effect of respiratory exercises on symptom scores, and number of rumination episodes. Key Results: There was no significant difference in baseline vagal tone between HV and RS. During the postprandial period, there was a trend to higher vagal tone in RS, but not significantly (P > .2 for all). RS had the higher total symptom scores than HV (P < .011). In RS, only DiaB decreased the number of rumination episodes during the intervention period (P = .028), while both DiaB and SlowDB increased vagal tone (P < .05 for both). The symptom scores with the 3 breathing exercises showed very similar trends. Conclusions and inferences: Patients with RS do not have decreased vagal tone related to meals. DiaB reduced number of rumination events by a mechanism not related to changes in vagal tone

Honeybee linguistics—a comparative analysis of the waggle dance among species of Apis

All honeybees use the waggle dance to recruit nestmates. Studies on the dance precision of Apis mellifera have shown that the dance is often imprecise. Two hypotheses have been put forward aimed at explaining this imprecision. The first argues that imprecision in the context of foraging is adaptive as it ensures that the dance advertises the same patch size irrespective of distance. The second argues that the bees are constrained in their ability to be more precise, especially when the source is nearby. Recent studies have found support for the latter hypothesis but not for the “tuned-error” hypothesis, as the adaptive hypothesis became known. Here we investigate intra-dance variation among Apis species. We analyse the dance precision of A. florea, A. dorsata, and A. mellifera in the context of foraging and swarming. A. mellifera performs forage dances in the dark, using gravity as point of reference, and in the light when dancing for nest sites, using the sun as point of reference. Both A. dorsata and A. florea are open-nesting species; they do not use a different point of reference depending on context. A. florea differs from both A. mellifera and A. dorsata in that it dances on a horizontal surface and does not use gravity but instead “points” directly toward the goal when indicating direction. Previous work on A. mellifera has suggested that differences in dance orientation and point of reference can affect dance precision. We find that all three species improve dance precision with increasing waggle phase duration, irrespective of differences in dance orientation, and point of reference. When dancing for sources nearby, dances are highly variable. When the distance increases, dance precision converges. The exception is dances performed by A. mellifera on swarms. Here, dance precision decreases as the distance increases. We also show that the size of the patch advertised increases with increasing distance, contrary to what is predicted under the tuned-error hypothesis

Retinal specific measurement of dark-adapted visual function: validation of a modified microperimeter

Background: Scotopic function is an important marker of many retinal diseases and is increasingly used as an outcome measure in clinical trials, such as those investigating gene therapy for Lebers congenital amaurosis. Scotopic visual function has traditionally been measured using an adapted perimetry system such as the Humphrey field analyser (HFA). However this system does not control for fixation errors or poor fixation stability. Here we evaluate the use of an adapted microperimeter to measure visual function at defined retinal regions under scotopic conditions.Methods: A MP-1 microperimeter (Nidek Technologies, Italy) was modified by adding a 1 log unit Neutral Density filter and a 530nm shortpass filter within the optical path of the instrument. Stray light was shielded. Fine matrix mapping perimetry was performed on five younger (65 years) subjects with no eye disease and good vision. All subjects were fully dark adapted before testing and pupils were dilated with 1% tropicamide. Tests was performed once on the modified MP-1 microperimeter and once using a modified HFA, in a counterbalanced order.Results: A foveal scotopic scotoma with a sensitivity reduction of >1 log unit was found using each instrument. In addition, the MP-1 system showed the retinal location of the foveal scotoma. Mean test time was 25 minutes for the MP-1 and 32 minutes for the HFA.Discussion: A modified MP-1 microperimeter can be used to measure scotopic retinal function, creating results which are comparable to the modified Humphrey field analyser. Advantages of the MP-1 system include the ability to track the retina through testing, retinal localisation of the scotoma and a faster test time

Agreement between frequency doubling perimetry and static perimetry in eyes with high tension glaucoma and normal tension glaucoma

Aims: To investigate the agreement in results between frequency doubling technology (FDT) and the conventional automated static perimeter in eyes with normal tension glaucoma (NTG) and high tension glaucoma (HTG). Methods: 72 eyes of 36 patients, who had two or more experiences with the Humphrey field analyser (HFA) program C30-2, were examined with the screening C-20-1 program of FDT. The result of FDT at each of the 17 stimulus points was graded as one of four categories. 58 out of 76 test points of HFA were assigned to one of the 17 clusters corresponding to FDT test points. Each cluster was represented as the lowest (scotoma of HFA) or the highest (threshold of HFA) probability symbol of total deviation (TD) of the HFA test points included in the cluster. The agreement between scotoma/threshold of HFA and FDT results was evaluated for NTG and HTG. Results: In a total of 65 eyes, the Spearman coefficients between the FDT and HFA (threshold/scotoma of HFA) were 0.599 and 0.515 (p<0.0001), respectively. In the HFA mean deviation matched 20 HTG eyes and 20 NTG eyes, the number of points with abnormal FDT results were 102 and 62 in eyes with HTG and NTG, respectively. The eyes with HTG had more abnormal FDT results than NTG eyes (p=0.0014, Mann-Whitney U test). The kappa coefficient between FDT and threshold of HFA in eyes with HTG and NTG was 0.288 and 0.520, respectively, and the agreement between FDT and scotoma of HFA was 0.480 and 0.439, respectively. Conclusions: The best agreement of the results of FDT and HFA was observed in eyes with NTG using threshold of HFA. The eyes with HTG showed lower agreement with more abnormal points in FDT results, which suggests enough sensitivity of FDT in eyes with NTG, and higher sensitivity of FDT in eyes with HTG