Inter-ictal assay of peripheral circulating inflammatory mediators in migraine patients under adjunctive cervical non-invasive vagus nerve stimulation (nVNS): A proof-of-concept study

Objective

To assay peripheral inter-ictal cytokine serum levels and possible relations with non-invasive vagus nerve stimulation (nVNS) responsiveness in migraineurs.

Host–microbiome interactions: the aryl hydrocarbon receptor as a critical node in tryptophan metabolites to brain signaling

ABSTRACT

Tryptophan (Trp) is not only a nutrient enhancer but also has systemic effects. Trp metabolites signaling through the well-known aryl hydrocarbon receptor (AhR) constitute the interface of microbiome-gut-brain axis. However, the pathway through which Trp metabolites affect central nervous system (CNS) function have not been fully elucidated. AhR participates in a broad variety of physiological and pathological processes that also highly relevant to intestinal homeostasis and CNS diseases. Via the AhR-dependent mechanism, Trp metabolites connect bidirectional signaling between the gut microbiome and the brain, mediated via immune, metabolic, and neural (vagal) signaling mechanisms, with downstream effects on behavior and CNS function. These findings shed light on the complex Trp regulation of microbiome-gut-brain axis and add another facet to our understanding that dietary Trp is expected to be a promising noninvasive approach for alleviating systemic diseases.     

The effect of level of injury and physical activity on heart rate variability following spinal cord injury

Objective/Background: To assess frequency domain heart rate variability (HRV) parameters at rest and in response to postural autonomic provocations in individuals with spinal cord injury (SCI) and investigate the autonomic influences on the heart of different physical activities.

Design: Cross-sectional study.

Methods: Ten subjects with complete cervical SCI and fourteen subjects with complete low thoracic SCI were prospectively recruited from the community and further divided in sedentary and physically active groups, the latter defined as regular weekly 4 hour physical activity for the preceding 3 months. Sixteen healthy individuals matched for sex and age were recruited to participate in the control group. The Low Frequency (LF), High Frequency (HF) powers and the LF/HF ratio of HRV were measured from continuous electrocardiogram (ECG) recordings at rest and after sitting using a fast Fourier transformation.

Outcome measures: The LF,HF, and the LF/HF ratio at rest and after sitting.

Results: A significant decrease in all HRV parameters in patients with SCI was found compared to controls. The change in HF, LF and LF/HF following sitting maneuver was significantly greater in controls as compared with the SCI group and greater in subjects with paraplegia as compared to subjects with tetraplegia. Better HRV values and enhanced vagal activity appears to be related to the type of physical activity in active subjects with paraplegia.

Conclusion: In this cohort of subjects spectral parameters of HRV were associated with the level of the injury. Passive standing was associated with higher HRV values in subjects with paraplegia.     

Auricular Vagal Nerve Stimulation Improves Constipation by Enhancing Colon Motility via the Central-Vagal Efferent Pathway in Opioid-Induced Constipated Rats

ObjectivesConstipation and opioid-induced constipation (OIC) are common with limited treatment options. We investigated whether a noninvasive method of auricular vagal nerve stimulation (aVNS) could be used for treating OIC and explored its potential mechanisms and neural pathways in a rodent model of OIC.Materials and MethodsSprague–Dawley were chronically implanted with one pair of auricular electrodes for aVNS. Sixteen rats were treated with loperamide for a week while another 16 rats received bilateral vagotomy, then randomly treated with aVNS or sham-aVNS for a week. In addition, eight normal rats were implanted with a polyethylene catheter in the proximal colon for assessing whole colon transit.Results1) The number of fecal pellets and water content in feces increased after aVNS, compared with sham-aVNS. 2) aVNS accelerated colon transit and whole gut transit, compared with sham-aVNS. 3) In colon tissues, aVNS increased the protein expression of choline acetyltransferase, glial cell line-derived neurotrophic factor and the c-kit expression in myenteric interstitial cells of Cajal but decreased the protein expression of neural nitric oxide synthase (p < 0.05 for all, vs. sham-VNS). 4) The prokinetic effects of aVNS were abolished by both subdiaphragmatic vagotomy and atropine. 5) aVNS increased the c-fos expression in both nucleus tractus solitarius and dorsal motor nucleus of vagus, and increased vagal efferent activity (p < 0.05, vs. sham-VNS).ConclusionsaVNS improves OIC by enhancing colon motility and restoring enteric neural functions mediated via the central and vagal efferent pathway.     

The effect of the addition of surface treated chopped and continuous poly (methyl methacrylate) fibres on some properties of acrylic resin

Poly (methyl methacrylate), the material most commonly used in the construction of dentures, is not without limitations particularly in terms of mechanical strength, such as flexural and fatigue strength. The Dental Practice Board for England statistics show that many dentures fail as a result of fracture. This study investigated the self-reinforcement of acrylic resin through the addition of surface treated poly (methyl methacrylate) fibres in chopped and continuous form. The effect of the addition of fibres on transverse and impact strengths was investigated. The addition of surface treated chopped or continuous fibres to acrylic resin did not improve the transverse or impact strengths. The addition of surface treated poly (methyl methacrylate), in the present form, to acrylic resin cannot be recommended as a method of reinforcement.     

Location,arrangement and possible function of interodontoblastic collagen fibres in association with calcium hydroxide-induced hard tissue bridges

AIM: To assess the location, arrangement and possible function of interodontoblastic collagen fibres in association with calcium hydroxide-induced hard tissue bridges by using light and transmission electron microscopy techniques and immunohistochemical staining localization. METHODOLOGY: Prior to the study, an animal use protocol form was reviewed and approved by the Screening Committee for Animal Research of the Tokyo Medical and Dental University. Exposed monkey pulps were capped with a hard-set calcium hydroxide and histopathologically evaluated at 3, 14, 21, 30 and 90 days, using light microscopy with silver staining and transmission electron microscopy to differentiate structural features of interodontoblastic collagen fibres. In addition, an attempt was made to identify and to differentiate between several types of collagen and fibronectin using immunohistochemical localization techniques. RESULTS: At 14 days, interodontoblastic collagen fibres were observed extending from the original dentine, passing through the odontoblasts, and consisted of two portions: a thick fibril and a thin fibril. At 21 days, interodontoblastic collagen fibres were seen penetrating into the predentine and becoming incorporated into the mineralized dentine. At 30 days, interodontoblastic collagen fibres reached the cell process. Although interodontoblastic collagen fibres were no longer observed near the odontoblastoid cells at the area of the newly formed tubular dentine, interodontoblastic collagen fibres were observed embedded within the primary formed dentine bridge. Immunohistochemical staining demonstrated type I collagen and fibronectin within the interodontoblastic collagen fibres. CONCLUSIONS: Interodontoblastic collagen fibres were routinely detected throughout early dentine bridges. Interodontoblastic collagen fibres are thought to be important for initial dentine bridging to induce and support a dentinogenesis framework.     

Cardiac autonomic activity during daytime nap in young adults

The current study investigated both sympathetic and vagal autonomic patterns during a daytime sleep in 25 healthy adults (23.2 ± 2.4 years). Pre‐ejection period (PEP; related inversely to beta‐adrenergic sympathetic activity), the interval between consecutive R‐waves (RR) and frequency‐domain heart rate variability (HRV) were computed during pre‐nap wakefulness and undisturbed sleep stages. Results showed sleep‐related changes in RR and HRV measures, whereas PEP decreased significantly from pre‐nap to sleep, showing no differences across sleep stages. Moreover, pre‐nap PEP and HFnu (the normalized unit of the high‐frequency component of HRV) were associated negatively with sleep latency and wake after sleep onset. These results indicate a marked autonomic output reduction during daytime sleep, with different stage‐dependent fluctuations for sympathetic and vagal activity. Importantly, pre‐nap autonomic activity seems to modulate subsequent sleep quality.     

Heart rate variability stabilization in athletes: towards more convenient data acquisition

Resting heart rate variability (HRV) is a potentially useful marker to consider for monitoring training status in athletes. However, traditional HRV data collection methodology requires a 5‐min recording period preceded by a 5‐min stabilization period. This lengthy process may limit HRV monitoring in the field due to time constraints and high compliance demands of athletes. Investigation into more practical methodology for HRV data acquisitions is required. The aim of this study was to determine the time course for stabilization of ECG‐derived lnRMSSD from traditional HRV recordings. Ten‐minute supine ECG measures were obtained in ten male and ten female collegiate cross‐country athletes. The first 5 min for each ECG was separately analysed in successive 1‐min intervals as follows: minutes 0–1 (lnRMSSD_0–1), 1–2 (lnRMSSD_1–2), 2–3 (lnRMSSD_2–3), 3–4 (lnRMSSD_3–4) and 4–5 (lnRMSSD_4–5). Each 1‐min lnRMSSD segment was then sequentially compared to lnRMSSD of the 5‐ to 10‐min ECG segment, which was considered the criterion (lnRMSSD_Criterion). There were no significant differences between each 1‐min lnRMSSD segment and lnRMSSD_Criterion, and the effect sizes were considered trivial (ES ranged from 0·07 to 0·12). In addition, the ICC for each 1‐min segment compared to the criterion was near perfect (ICC values ranged from 0·92 to 0·97). The limits of agreement between the prerecording values and lnRMSSD_Criterion ranged from ±0·28 to ±0·45 ms. These results lend support to shorter, more convenient ECG recording procedures for lnRMSSD assessment in athletes by reducing the prerecording stabilization period to 1 min.