Kategoriarkiv: Forskning og artikler

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Heart rate variability biofeedback: how and why does it work?

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Bekrefter alle elementer jeg jobber med i Autonom pust: vagus, betennelse, m.m.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4104929/

In recent years there has been substantial support for heart rate variability biofeedback (HRVB) as a treatment for a variety of disorders and for performance enhancement (Gevirtz, 2013). Since conditions as widely varied as asthma and depression seem to respond to this form of cardiorespiratory feedback training, the issue of possible mechanisms becomes more salient. The most supported possible mechanism is the strengthening of homeostasis in the baroreceptor (Vaschillo et al., 2002; Lehrer et al., 2003). Recently, the effect on the vagal afferent pathway to the frontal cortical areas has been proposed. In this article, we review these and other possible mechanisms that might explain the positive effects of HRVB.

ANTI-INFLAMMATORY EFFECTS

It is known that the vagal system interacts closely with the inflammatory system, such that increases in vagus nerve traffic (usually produced by electrical vagal stimulation) are associated with decreases in serum levels of various inflammatory cytokines (Borovikova et al., 2000; Tracey, 2002). One study did find a decrease in C-reactive proteins among hypertensive patients treated with HRV biofeedback (Nolan et al., 2012). In another study, we experimentally exposed healthy subjects to an inflammatory cytokine, lipopolysaccharide (Lehrer et al., 2010). Usually both sympathetic and parasympathetic activity is blocked by lipopolysaccharide. Although no biofeedback-induced decreases in inflammatory cytokines were found, the autonomic effects of inflammation were greatly modulated, indicating that a greater resiliency was preserved among individuals given HRV biofeedback.

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Matoverfølsomhet – et paradigmeskifte

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Artikkel skrevet i 2011 som nevner mange viktige poenger. Blandt annet at vagus svekkes ved IBS og at det gir andre plager, spesielt hudplager.

Klikk for å få tilgang til matoverfoelsomhet_aip_1_2011w_v2.pdf

Dessuten hadde mange pasienter ekstra-intesti- nale symptomer og skåret høyt på «Subjective Health Complaints» (1). Påfallende mange anga at de hadde kronisk tretthet samt leddsmerter med morgenstivhet uten påvisbar artritt. Livskvaliteten var til dels be- tydelig redusert (2).

Over 50% av pasientene tilfreds- stilte kravene til en psykiatrisk diag- nose. Men hvor mye av de psykologiske problemene kan være sekundære? Inntil for knapt 20 år siden ble også magesårsykdommen regnet som en psykosomatisk sykdom. De psykolo- giske problemene vi så hos ulcuspasi- entene var ganske like de vi nå finner hos de matoverfølsomme, og vi har enda friskt i minnet hvordan alle pro- blemene hos ulcuspasientene, in- kludert de psykologiske, «blåste bort» etter fjerning av magesårbakterien Helicobacter pylori (4).

Kun sykdomspesifikk angst eller for- ventninger om plager var signifikante uavhengige prediktorer. Disse pre- diktorene forklarte dog til sammen ikke mer enn 10% av variansen i mageplagene, og alder var eneste signifikante prediktor av ekstra- intestinale plager. Det vil si at 90% av variansen i grad av somatiske plager ikke kunne forklares av psyko- logiske faktorer. Vi tror derfor nå at mange av de psykologiske problemene ved matoverfølsomhet er sekundære og at betydningen av psykologiske faktorer som årsak til matoverfølsomhet kan være betydelig overdrevet.

Vi kunne vise at et tungt fordøyelig, men fermenter- bart karbohydrat, som laktulose, ofte reproduserte pasientens plager (6). tester på klassisk IgE-sensitivisering mot spesifikke kostproteiner, deri- mot, var sjeldent positive. Det virker som om mageplagene først og fremst trigges av tungt fordøyelige karbo- hydrater og ikke spesielt av proteiner i kosten. Dessuten, at plagene kunne reproduseres av mat, viser at pasien- ten har rett – plagene kan skyldes maten! Det passer med at pasientene ikke har plager om natta, når de faster, etter tarm- skylling eller når de får tømt seg fullstendig.

Over 60% av pasientene hadde indikasjon på atopisk sykdom (Dette er hud- og slimhinnerelaterte sykdommer som allergi, tørr hud, kløe, m.m.)

Histamin øker sympatisk og redusert para- sympatisk (vagal) tonus, som også er karakteristisk for pasienter med funksjonelle mageplager (16, 17). Slik endret autonom aktivitet kan være et resultat av IgE-mediert histaminfrigjøring fra lokalt sensibili- serte mastceller (18).

Systemiske symptomer som kro- nisk tretthet og leddsmerter hos pasi- enter med IBS har tidligere ofte blitt forklart som somatisering av psykolo- giske problemer, men det finnes andre muligheter. For eksempel er det nylig rapportert at symptomer ved kronisk tretthetssyndrom kan behandles med en B-celle-antagonist (rituximab) (21). I likhet med de matoverfølsomme, har pasienter med kronisk tretthets- syndrom ofte IBS og endret mikro- flora som kan være av betydning for immunaktiveringen hos disse pasi- entene (22). Hos matoverfølsomme med IBS har vi nylig påvist økt nivå av B-celle aktiverende faktor (BAFF) i blod og tarmskyllevæske (23). BAFF er relatert til autoimmunitet og lokal immunaktivering i tarmen («lokal allergi») (24).

At karbohydrater kan reprodusere mageplagene hos pasienter med IBS og matoverfølsomhet, er verdt å merke seg, og mye tyder på at dette allerede nå bør få terapeutiske konsekvenser (27). Vi ser med andre ord for oss et paradigmeskifte når det gjelder utredning og behandling av pasienter med IBS og matoverfølsomhet.

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Central sensitisation in visceral pain disorders

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Nevner hvordan IBS skaper sentralsensitering og hyperalgesia andre steder enn bare tarmen, og bidrar til mange muskel- og ledd problemer. Nevner at dette spesielt skjer i korsryggen hvor sensoriske nerver fra tarmen treffer samme nerve i ryggmargen som de sensoriske nervene fra beina.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1856337/

The concept of visceral hyperalgesia has been examined in a variety of functional gastrointestinal disorders (FGIDs), including oesophagitis, gastro‐oesophageal reflux disease, non‐ulcer dyspepsia, gastroparesis, and irritable bowel syndrome (IBS). Visceral hypersensitivity has also been demonstrated in non‐gastrointestinal disorders such as interstitial cystitis and ureteric colic.1 Although the pathophysiological mechanisms of pain and hypersensitivity in these disorders are still not well understood, exciting new developments in research have been made in the study of the brain‐gut interactions involved in the FGIDs.

In this issue of Gut, Sarkar and colleagues2 address the phenomenon of temporal summation of pain, termed “wind‐up”, and its relationship to central sensitisation and secondary visceral pain hyperalgesia caused by acidification of the oesophagus (see page 920). Also in this issue of Gut, Drewes and colleagues3 examine peripheral and central sensitisation using both mechanical and thermal stimuli in patients with oesophagitis compared with control subjects (see page 926). They found that in patients with oesophagitis, the interaction between central and peripheral nociceptive input may help explain patient symptoms. Understanding the implications of these two studies requires examining the concept of central sensitisation in visceral pain disorders. Both of these studies have important clinical and research ramifications for the study of FGIDs.

“Hypersensitivity in IBS patients is not just limited to the gut and more widespread alterations in central pain processing may be involved in this chronic pain disorder”

The most pronounced hyperalgesia appears to occur at the lumbosacral level at which colon and lower extremity nociceptive afferents are likely to converge onto common spinal segments, explaining why patients had higher thermal hypersensitivity in the foot than in the hand (see fig 1​1).14,15,19

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Relationship between daily physical activity level and low back pain in young, female desk-job workers.

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For mye trening og for lite trening gir ryggsmerter. Akkurat passe mye trening er best.

http://www.ncbi.nlm.nih.gov/pubmed/25261333

Abstract

OBJECTIVES:

The purpose of this study was to investigate the relationship between daily physical activity (PA) level and low back pain (LBP) in young women.

MATERIAL AND METHODS:

Two hundred forty three female, desk-job workers aged 20-40 voluntarily participated in the study. The participants were assessed by the use of Oswestry Disability Index for measuring LBP disability and by the use of the short version of the International Physical Activity Questionnaire for PA assessment. The 1-way ANOVA test was used for comparing the mean values according to the physical activity level groups. Correlations between the average LBP disability score and all the other variables were obtained using Pearson’s correlation analysis. The level of statistical significance was p < 0.05.

RESULTS:

Significant differences were found for LBP disability score between the results of 3 different PA groups (p < 0.05) (low, moderate and high PA groups). The correlation between the average LBP disability score and body weight (r = 0.187, p < 0.01), body mass index (r = 0.165, p < 0.01), vigorous MET score (r = 0.247, p < 0.01) and total PA MET score (r = 0.131, p < 0.01) were significant.

CONCLUSIONS:

The main finding of this study is that there is a U-shaped relationship between PA and LBP disability score in young women. A moderate level of daily physical activity and preventing body weight and fat gain should be recommended in young, female desk-job workers in order to prevent and manage low back pain.

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Efficacy of paced breathing for insomnia: Enhances vagal activity and improves sleep quality.

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Nevner at 0,1 Hz pust (5x minuttet) styrker vagusnerven slik at søvnen blir bedre for de som har insomnia. Her gjorde de det i 20 minutter før de la seg til å sove.

http://www.ncbi.nlm.nih.gov/pubmed/25234581

Abstract

Fourteen self-reported insomniacs (SRI) and 14 good sleepers (GS) had their cardiac neuronal activity assessed by heart rate variability (HRV) under controlled respiration at a slow frequency rate of 0.1 Hz, and a forced rate of 0.2 Hz during daytime rest. Nighttime sleep was measured by polysomnography. The SRI showed depressed high frequency power of HRV compared to the GS. An increased total power of HRV was observed among the SRI during slow, paced breathing compared with spontaneous breathing and 0.2 Hz. Sleep onset latency, number of awakenings, and awakening time during sleep were decreased and sleep efficiency was increased if SRI practiced slow, paced breathing exercises for 20 min before going to sleep. Our results indicate that there is autonomic dysfunction among insomniacs, especially in relation to vagal activity; however, this decreased vagal activity can be facilitated by practicing slow, paced breathing, thereby improving sleep quality.

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High Energy Diets-Induced Metabolic and Prediabetic Painful Polyneuropathy in Rats

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Nevner hvordan høy-fett høy-karbo forværrer nevropati (ødelagte nerver), men høy-fett høy-karbo høy-salt ser ut til å dempe smertene noe.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3581455/

Conclusions

In the current study, early metabolic syndrome (hyperinsulinemia, dyslipidemia, and hypertension) and prediabetic conditions (IFG) could be induced by high energy (high-fat and high-sucrose) diets in rats which later developed painful polyneuropathy that was characterized by myelin breakdown and LMF loss in both peripheral and central branches of primary afferent neurons. However, SMF and UMF were far less damaged in the same rats. The phenomenon that the high energy diets only induce mechanical, but not thermal, pain hypersensitivity may reflect a selective damage to LMF, but not to the SMF and UMF. Moreover, dietary sodium (high-salt) deteriorates the neuropathic pathological process induced by high energy diets further, but paradoxically high salt consumption may improve, at least temporarily, chronic pain perception in these animals.

We have therefore established a strong link between high-energy/high-salt diet induced metabolic syndrome and prediabetes which results in relatively selective LMF damage in both the PNS and CNS that in turn can result in neuropathic pain. These results have a profound impact on patient welfare relative to diet choice, not just for T2DM onset, but also for its associated neuropathic symptoms.

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Melatonin prevents mitochondrial dysfunction and insulin resistance in rat skeletal muscle.

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Om hvordan melatonin beskytter mitokondriene i muskler og insulin resistens.

Teodore et.al. 2014. http://www.ncbi.nlm.nih.gov/pubmed/24981026

Abstract

Melatonin has a number of beneficial metabolic actions and reduced levels of melatonin may contribute to type 2 diabetes. The present study investigated the metabolic pathways involved in the effects of melatonin on mitochondrial function and insulin resistance in rat skeletal muscle. The effect of melatonin was tested both in vitro in isolated rats skeletal muscle cells and in vivo using pinealectomized rats (PNX). Insulin resistance was induced in vitro by treating primary rat skeletal muscle cells with palmitic acid for 24 hr. Insulin-stimulated glucose uptake was reduced by palmitic acid followed by decreased phosphorylation of AKT which was prevented my melatonin. Palmitic acid reduced mitochondrial respiration, genes involved in mitochondrial biogenesis and the levels of tricarboxylic acid cycle intermediates whereas melatonin counteracted all these parameters in insulin-resistant cells. Melatonin treatment increases CAMKII and p-CREB but had no effect on p-AMPK. Silencing of CREB protein by siRNA reduced mitochondrial respiration mimicking the effect of palmitic acid and prevented melatonin-induced increase in p-AKT in palmitic acid-treated cells. PNX rats exhibited mild glucose intolerance, decreased energy expenditure and decreased p-AKT, mitochondrial respiration, and p-CREB and PGC-1 alpha levels in skeletal muscle which were restored by melatonin treatment in PNX rats. In summary, we showed that melatonin could prevent mitochondrial dysfunction and insulin resistance via activation of CREB-PGC-1 alpha pathway. Thus, the present work shows that melatonin play an important role in skeletal muscle mitochondrial function which could explain some of the beneficial effects of melatonin in insulin resistance states.

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An acid-sensing ion channel that detects ischemic pain

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Nevner mange interessante ting om hvordan lav pH som følge av CO2 ikke er det samme som lav pH som følge av f.eks. melkesyre(laktic acid). De sier at melkesyre og ATP må være sammen for å gjøre pH-sensitive nerver aktive. Noe som skjer ved hard trening hvor ATP lekker ut fra muskel cellene. Laktat aktiverer ASICs umiddelbart, mens ATP er «treg» og det skjer i løpet av 30-60 sekunder. Kanskje denne overaskelsen i nervesystemet er utgangspunktet for sentralsensiteringen som skjer ved DOMS?

http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2005001100001

Paradox number 2 answered: coincident detection of lactate, ATP and acid

We are left with a seemingly more profound paradox: how can acid be relevant to ischemic pain if no pain is caused by metabolic events such as hypercapnia that can cause the same kind of pH change that occurs during a heart attack? Pan et al. (13) demonstrated the paradox most convincingly. They measured the pH on the surface of the heart when a coronary artery was blocked and found that it dropped from pH 7.4 to 7.0. Then they reperfused the artery and had the animal breathe carbon dioxide until the resulting hypercapnia dropped the pH of the heart to 7.0. The blockade of the artery caused increased firing of sensory axons that innervate the heart, but the hypercapnia did not. How can this observation be reconciled with their other result (see above) that buffering extracellular pH greatly diminishes axon firing during artery occlusion? The simple interpretation is that protons must be necessary to activate the sensory axons, but cannot by themselves be sufficient. In other words, something must act together with protons to activate the axons.

We searched for compounds released during ischemia that might act together with protons to activate ASIC3. We found two: lactate and adenosine 5′-triphosphate (ATP). When the channel is activated by pH 7.0 in the presence of 15 mM lactate, the resulting current is 80% greater than when lactate is absent (Figure 6). These are physiological values. Under resting conditions, extracellular lactate is about 1 mM in skeletal muscle; after extreme ischemic exercise it rises to 15-30 mM (26). The increased current in the presence of lactate makes the channel better at sensing the lactic acidosis that occurs in ischemia than other kinds of acidosis such as the carbonic acidosis when an animal breathes CO2.

Extracellular ATP rises to >10 µM when a muscle contracts without blood flow (27). We find that a transient appearance of such extracellular ATP can greatly increase ASIC3 current even for minutes after the ATP is removed (Figure 7).

Though they both increase ASIC3 current, lactate and ATP have qualitatively different effects. Lactate acts immediately and must be present for the ASIC current to be enhanced. ATP increases the current slowly – a peak is reached between 15 s and 1 min after ATP is applied – and the effect persists for minutes after ATP is removed. Also, lactate acts on every cell that expresses ASIC3 whereas ATP acts on some cells but not others. We find that lactate acts by altering the basic gating of the channel, which, surprisingly, involves binding of calcium in addition to protons (28). In contrast, the ATP binding site must not be the ASIC3 channel itself; there are a variety of purinergic receptors, some of which are ion channels and some of which are G-protein-coupled receptors. We are presently asking if any of these known receptors might mediate ATP modulation of ASIC3.