Brain regions involved in fatigue sensation: reduced acetylcarnitine uptake into the brain

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: the biology of a neglected disease

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a chronic, debilitating disease characterised by a wide range of symptoms that severely impact all aspects of life. Despite its significant prevalence, ME/CFS remains one of the most understudied and misunderstood conditions in modern medicine. ME/CFS lacks standardised diagnostic criteria owing to variations in both inclusion and exclusion criteria across different diagnostic guidelines, and furthermore, there are currently no effective treatments available. Moving beyond the traditional fragmented perspectives that have limited our understanding and management of the disease, our analysis of current information on ME/CFS represents a significant paradigm shift by synthesising the disease's multifactorial origins into a cohesive model. We discuss how ME/CFS emerges from an intricate web of genetic vulnerabilities and environmental triggers, notably viral infections, leading to a complex series of pathological responses including immune dysregulation, chronic inflammation, gut dysbiosis, and metabolic disturbances. This comprehensive model not only advances our understanding of ME/CFS's pathophysiology but also opens new avenues for research and potential therapeutic strategies. By integrating these disparate elements, our work emphasises the necessity of a holistic approach to diagnosing, researching, and treating ME/CFS, urging the scientific community to reconsider the disease's complexity and the multifaceted approach required for its study and management.

Repetitive transcranial magnetic stimulation ameliorates symptoms in patients with myalgic encephalomyelitis (chronic fatigue syndrome)

Background

Central nervous system dysfunction has been postulated to cause debilitating symptoms in patients with myalgic encephalomyelitis (ME) (originally called "chronic fatigue syndrome"). Repetitive transcranial magnetic stimulation (rTMS) is a newly developed neuromodulatory procedure and has been suggested to facilitate the cortical neural activity.

Methods

This study enrolled 30 patients with ME (7 men and 23 women) with a mean age of 39 ± 12 years, who received rTMS treatment of both the left dorsolateral prefrontal cortex and the left primary motor area in the brain. The performance status score (0-9) for restricting activities of daily living, orthostatic intolerance (OI) during a 10-min standing test, neurologic disequilibrium diagnosed as unstable standing with their feet together and eyes closed, neuropathic pain or fibromyalgia, and muscle weakness were compared before and after treatment.

Results

After therapy, favorable effects were observed with a decrease in performance status score or index for restriction of activities of daily living of ≥ 2 points in 20 patients (67%). OI with the inability to complete the 10-min standing test was resolved in 10 (83%) out of 12 patients, and disequilibrium was resolved in 15 (88%) out of 17 patients. Neuropathic pain or fibromyalgia was attenuated in seven (70%) out of 10 patients. Muscle weakness with grip power of < 10 kg was resolved in two (50%) out of four patients. No untoward effects were encountered in all the study patients.

Conclusion

The treatment with rTMS is effective in alleviating various symptoms, especially OI and disequilibrium, and in improving the activities of daily living in patients with ME.

Sex Differences in the Correlation between Fatigue Perception and Regional Gray Matter Volume in Healthy Adults: A Large-Scale Study

The relationship between fatigue perception and regional gray matter volume (rGMV) has seldom been studied in healthy adults. Therefore, this study aimed to analyze sex differences in the correlation between rGMV and fatigue perception using Chalder’s fatigue questionnaire (CFQ). The CFQ was used to analyze the sexual features of rGMV related to the degree of perceived fatigue in 2955 healthy adults (male = 1560, female = 1395) of various ages (20–89 years, median 56). A higher CFQ score denotes a higher perceived fatigue level by the participant. According to the CFQ scores in males, the volumes of the right orbital part of the inferior frontal gyrus and left precuneus were negatively correlated (i.e., smaller rGMV had a higher CFQ score), whereas the left angular gyrus was positively correlated. In females, the right inferior temporal gyrus was negative, whereas the left middle temporal gyrus and right putamen were positive (i.e., larger rGMV had a higher CFQ score). The lack of identified regions in this large-scale study between males and females might be related to sex differences in clinical or pathological fatigue morbidities. Additionally, the sex differences in the negative or positive correlations between rGMV and fatigue perception may contribute to a better understanding of the neuronal mechanism in the early stages of fatigue development.

Animal Models for Neuroinflammation and Potential Treatment Methods

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating chronic disease of unknown etiology and without effective treatment options. The onset of ME/CFS is often associated with neuroinflammation following bacterial or viral infection. A positron emission tomography imaging study revealed that the degree of neuroinflammation was correlated with the severity of several symptoms in patients with ME/CFS. In animal studies, lipopolysaccharide- and polyinosinic-polycytidylic acid-induced models are thought to mimic the pathological features of ME/CFS and provoke neuroinflammation, characterized by increased levels of proinflammatory cytokines and activation of microglia. In this review, we described the anti-inflammatory effects of three compounds on neuroinflammatory responses utilizing animal models. The findings of the included studies suggest that anti-inflammatory substances may be used as effective therapies to ameliorate disease symptoms in patients with ME/CFS.

The pathophysiology of leg cramping during dialysis and the use of carnitine in its treatment

Leg cramping is a common side effect of hemodialysis, and this is frequently treated by the administration of carnitine, but this is not effective in every patient. Alkalosis is a key component of the etiology of leg cramping during hemodialysis sessions. This is mediated through the binding of calcium ions to serum albumin, which causes hypocalcemia, and an increase in the release of calcium ions from the sarcoplasmic reticulum. Normally the calcium pump on the sarcoplasmic reticulum consumes ATP and quickly reuptakes the released calcium ions, which rapidly stops excessive muscle contractions. Thus, carnitine deficiency results in prolonged muscle contraction because of ATP depletion. However, during ATP production, carnitine is only involved up to the stage of acyl-CoA transport into mitochondria, and for the efficient generation of ATP, the subsequent metabolism of acyl-CoA is also important. For example, β-oxidation and the tricarboxylic acid cycle may be affected by a deficiency of water-soluble vitamins and the electron transport chain requires coenzyme Q10, but statins inhibit its production. The resulting accumulation of excess long-chain acyl-CoA in mitochondria inhibits enzymes involved in energy production. Thus, carnitine administration may be used more effectively if clinicians are aware of its specific physiologic roles.

Alterations in Urine Metabolomics Following Sport-Related Concussion: A 1H NMR-Based Analysis

Objective: Millions of sport-related concussions (SRC) occur annually in North America, and current diagnosis of concussion is based largely on clinical evaluations. The objective of this study was to determine whether urinary metabolites are significantly altered post-SRC compared to pre-injury.

Setting: Outpatient sports medicine clinic.

Participants: Twenty-six male youth sport participants.

Methods: Urine was analyzed pre-injury and after SRC by ¹H NMR spectroscopy. Data were analyzed using multivariate statistics, pairwise t-test, and metabolic pathway analysis. Variable importance analysis based on random variable combination (VIAVC) was applied to the entire data set and resulted in a panel of 18 features. Partial least square discriminant analysis was performed exploring the separation between pre-injury and post-SRC groups. Pathway topography analysis was completed to identify biological pathway involvement. Spearman correlations provide support for the relationships between symptom burden and length of return to play and quantifiable metabolic changes in the human urinary metabolome.

Results: Phenylalanine and 3-indoxysulfate were upregulated, while citrate, propylene glycol, 1-methylhistidine, 3-methylhistidine, anserine, and carnosine were downregulated following SRC. A receiver operator curve (ROC) tool constructed using the 18-feature classifier had an area under the curve (AUC) of 0.887. A pairwise t-test found an additional 19 altered features, 7 of which overlapped with the VIAVC analysis. Pathway topology analysis indicated that aminoacyl-tRNA biosynthesis and beta-alanine metabolism were the two pathways most significantly changed. There was a significant positive correlation between post-SRC 2-hydroxybutyrate and the length of return to play (ρ = 0.482, p = 0.02) as well as the number of symptoms and post-SRC lactose (ρ = 0.422, p = 0.036).

Conclusion: We found that ¹H NMR metabolomic urinary analysis can identify a set of metabolites that can correctly classify SRC with an accuracy of 81.6%, suggesting potential for a more objective method of characterizing SRC. Correlations to both the number of symptoms and length of return to play indicated that 2-hydroxybutyrate and lactose may have potential applications as biomarkers for sport-related concussion.

Analgesic and Antidepressant Effects of the Clinical Glutamate Modulators Acetyl-L-Carnitine and Ketamine

Pain and depression are leading causes of disability and of profound social and economic burden. Their impact is aggravated by their chronicity and comorbidity and the insufficient efficacy of current treatments. Morphological and functional metabolism studies link chronic pain and depressive disorders to dysfunctional neuroplastic changes in fronto-limbic brain regions that control emotional responses to painful injuries and stressful events. Glutamate modulators are emerging new therapies targeting dysfunctional brain areas implicated in the generation and maintenance of chronic pain and depression. Here, we report the effects of two clinically approved glutamate modulators: acetyl-L-carnitine (ALCAR) and S, R(±)ketamine (KET). ALCAR is a natural neurotrophic compound currently marketed for the treatment of neuropathies. KET is the prototypical non-competitive antagonist at N-methyl-D-aspartate glutamate receptors and a clinically approved anesthetic. Although they differ in pharmacological profiles, ALCAR and KET both modulate aminergic and glutamatergic neurotransmissions and pain and mood. We assessed in rats the effects of ALCAR and KET on cerebral metabolic rates for glucose (rCMRglc) and assessed clinically the effects of ALCAR in chronic pain and of KET in post-operative pain. ALCAR and KET increased rCMRglc at similar degrees in prefrontal, somatosensory, and cingulate cortices, and KET increased rCMRglc at a different, much larger, degree in limbic and dopaminergic areas. While rCMRglc increases in prefrontal cortical areas have been associated with analgesic and antidepressant effects of ALCAR and KET, the marked metabolic increases KET induces in limbic and dopaminergic areas have been related to its psychotomimetic and abuse properties. In patients with chronic neuropathic pain, ALCAR (1,000 mg/day) yielded to a fast (2 weeks) improvement of mood and then of pain and quality of life. In day-surgery patients, KET improved dischargeability and satisfaction. In obese patients undergoing bariatric surgery, a single, low dose of KET (0.5 mg/kg) at induction of anesthesia determined a very fast (hours) amelioration of post-operative depression and pain and an opioid-sparing effect. These findings indicate that ALCAR and KET, two non-selective glutamate modulators, still offer viable therapeutic options in comorbid pain and depression.

Liver-Oriented Acute Metabolic Effects of A Low Dose of L-Carnitine under Fat-Mobilizing Conditions: Pilot Human Clinical Trial

The acute metabolic effect of low dosages of L-carnitine under fat-mobilizing conditions was investigated. Healthy subjects (Study 1: n=5; Study 2: n=6) were asked to fast overnight. Then, 30 min of aerobic exercise on a cycle ergometer was performed after supplementation, followed by a 3.5-h sedentary recovery phase. The following ingestion patterns were used: Study 1 (i) noningestion, (ii) 750 mg of L-carnitine (LC), and (iii) 750 mg of LC+50 g of carbohydrate (CHO); Study 2 (iv) noningestion, (v) 500 mg of LC, (vi) 30 mg of CoQ₁₀, and (vii) 500 mg of LC+30 mg of CoQ₁₀. The energy expenditure (EE) and nonprotein respiratory quotient (npRQ) were measured during the pre-exercise, postexercise, and recovery periods. Serum free carnitine, acetylcarnitine, total carnitine (Study 1 and 2), and ketone bodies (Study 2) were measured. The 750 mg LC treatment significantly facilitated fat oxidation during the recovery phases (p<0.05) without elevating EE. The higher fat oxidation associated with LC was completely suppressed by CHO. CoQ₁₀ affected neither npRQ nor EE. npRQ was significantly correlated with the serum total ketone bodies (R=-0.68, p<0.001) and acetylcarnitine (R=-0.61--0.70, p<0.001). The highest correlation was found between acetylcarnitine and total ketone bodies immediately after exercise (R=0.85, p<0.001). In conclusion, LC enhanced liver fat utilization and ketogenesis in an acute manner without stimulating EE under fat-mobilizing conditions.

Effect of L-carnitine on health-related quality of life in patients with liver cirrhosis

L-carnitine (4-N-trimethylammonium-3-hydroxybutyric acid) is the physiologically active form of carnitine and is a natural compound that has been shown to exhibit antioxidant activity. L-carnitine is used as a supplementary treatment in patients with cirrhosis with hepatic encephalopathy, hyperammonemia or muscle cramps. In the present study, the effect of L-carnitine supplementation on health-related quality of life in 30 patients with cirrhosis was prospectively examined. L-carnitine (1,800 mg/day) was administered orally for 6 months. To assess the effects of L-carnitine on chronic fatigue, patients filled out a self-report questionnaire regarding their physical and mental health. The levels of total and free carnitine, and acylcarnitine were found to be significantly higher 1, 3 and 6 months after therapy initiation compared with before treatment. Serum albumin levels were significantly increased 3 and 6 months after initiation of therapy. L-carnitine supplementation significantly increased the BAP/d-ROM ratio, a marker of antioxidant status in patients with cirrhosis. Changes in serum carnitine concentrations were positively correlated with changes in serum albumin levels (R²=0.369; P=0.012), but not with changes in serum ammonia levels (R²= 0.005; P=0.78). Total and mental health scores improved significantly, and physical scores improved marginally 3 and 6 months after initiation of L-carnitine. These findings may be attributed to the enhanced serum albumin levels and oxidative stress rather than the reduced serum ammonia levels. Based on these results, it is suggested that L-carnitine can potentially alleviate chronic fatigue, along with the increased BAP/d-ROM ratio, which were involved in increased oxidative stress in patients with cirrhosis. The specific mechanisms by which L-carnitine ameliorates chronic fatigue is not fully understood and requires further investigation.

Aging-Related Disorders and Mitochondrial Dysfunction: A Critical Review for Prospect Mitoprotective Strategies Based on Mitochondrial Nutrient Mixtures

A number of aging-related disorders (ARD) have been related to oxidative stress (OS) and mitochondrial dysfunction (MDF) in a well-established body of literature. Most studies focused on cardiovascular disorders (CVD), type 2 diabetes (T2D), and neurodegenerative disorders. Counteracting OS and MDF has been envisaged to improve the clinical management of ARD, and major roles have been assigned to three mitochondrial cofactors, also termed mitochondrial nutrients (MNs), i.e., α-lipoic acid (ALA), Coenzyme Q10 (CoQ10), and carnitine (CARN). These cofactors exert essential–and distinct—roles in mitochondrial machineries, along with strong antioxidant properties. Clinical trials have mostly relied on the use of only one MN to ARD-affected patients as, e.g., in the case of CoQ10 in CVD, or of ALA in T2D, possibly with the addition of other antioxidants. Only a few clinical and pre-clinical studies reported on the administration of two MNs, with beneficial outcomes, while no available studies reported on the combined administration of three MNs. Based on the literature also from pre-clinical studies, the present review is to recommend the design of clinical trials based on combinations of the three MNs.

Neuroimaging characteristics of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS): a systematic review

BACKGROUND

Since the 1990s, neuroimaging has been utilised to study Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS), a debilitating illness with unknown aetiology. While brain abnormalities in ME/CFS have been identified, relatively little is known regarding which specific abnormalities are consistently observed across research groups and to what extent the observed abnormalities are reproducible.

METHOD

To identify consistent and inconsistent neuroimaging observations in ME/CFS, this retrospective and systematic review searched for studies in which neuroimaging was used to investigate brain abnormalities in ME/CFS in Ovid MEDLINE, PubMed (NCBI), and Scopus from January 1988 to July 2018. A qualitative synthesis of observations was performed to identify brain abnormalities that were consistently and inconsistently reported.

RESULTS

63 full-text articles were included in the synthesis of results from 291 identified papers. Additional brain area recruitment for cognitive tasks and abnormalities in the brain stem are frequent observations in 11 and 9 studies using different modalities from different research teams respectively. Also, sluggish blood oxygenation level-dependent (BOLD) signal responses to tasks, reduced serotonin transporters, and regional hypometabolism are consistent observations by more than two research teams. Single observations include abnormal brain tissue properties, regional metabolic abnormalities, and association of brain measures with ME/CFS symptoms. Reduced resting cerebral blood flow and volumetric brain changes are inconsistent observations across different studies.

CONCLUSION

Neuroimaging studies of ME/CFS have frequently observed additional brain area recruitment during cognitive tasks and abnormalities in the brain stem. The frequent observation of additional brain area recruitment and consistent observation of sluggish fMRI signal response suggest abnormal neurovascular coupling in ME/CFS.

Homeostatic disturbance of thermoregulatory functions in rats with chronic fatigue

Chronic fatigue syndrome (CFS) is characterized by long-lasting fatigue, and a range of symptoms, and is involved in homeostasis disruption. CFS patients frequently complain of low grade fever or chill even under normal body temperature indicating that thermosensory or thermoregulatory functions might be disturbed in CFS. However, little is known about the detailed mechanisms. To elucidate whether and how thermoregulatory function was altered during the development of chronic fatigue, we investigated temporal changes in body temperature with advance of fatigue accumulation in a chronic fatigue rat model using a wireless transponder. Our findings demonstrated that the body temperature was adaptively increased in response to fatigue loading in the early phase, but unable to retain in the late phase. The tail heat dissipation was often observed and the frequency of tail heat dissipation gradually increased initially, then decreased. In the late phase of fatigue loading, the body temperature for the tail heat dissipation phase decreased to a value lower than that for the non-dissipation phase. These results suggest that adaptive changes in thermoregulatory function occurred with fatigue progression, but this system might be disrupted by long-lasting fatigue, which may underlie the mechanism of fatigue chronification.

Metabolic signature in nucleus accumbens for anti-depressant-like effects of acetyl-L-carnitine

Emerging evidence suggests that hierarchical status provides vulnerability to develop stress-induced depression. Energy metabolic changes in the nucleus accumbens (NAc) were recently related to hierarchical status and vulnerability to develop depression-like behavior. Acetyl-L-carnitine (LAC), a mitochondria-boosting supplement, has shown promising antidepressant-like effects opening therapeutic opportunities for restoring energy balance in depressed patients. We investigated the metabolic impact in the NAc of antidepressant LAC treatment in chronically-stressed mice using ¹H-magnetic resonance spectroscopy (¹H-MRS). High rank, but not low rank, mice, as assessed with the tube test, showed behavioral vulnerability to stress, supporting a higher susceptibility of high social rank mice to develop depressive-like behaviors. High rank mice also showed reduced levels of several energy-related metabolites in the NAc that were counteracted by LAC treatment. Therefore, we reveal a metabolic signature in the NAc for antidepressant-like effects of LAC in vulnerable mice characterized by restoration of stress-induced neuroenergetics alterations and lipid function.

Application of autonomic nervous function evaluation to job stress screening

The present study focuses on the evaluation of autonomic nervous function, which is increasingly being used as an objective measure of fatigue state. It has recently been reported that autonomic nervous activity, which is expressed as total heart rate variability (HRV) power, is associated with, and can be used as an objective measure of, mental and physical fatigue. Total HRV power (log (LF + HF)) has been shown to decline with ageing, and thus cannot be utilized as a fatigue index in populations with a different age composition. In the present study, we devised standard scores (deviation value) for autonomic nervous activity corrected for individual age calculated from the distribution of such activity in individual age cohorts. This allowed us to accurately evaluate an individual's autonomic nervous activity, even when that individual was part of a group with members of different ages. Standard scores were quantified using autonomic nervous function data gathered from 1,969 healthy individuals (age range 20–77 years).

The efficacy of this method in mental health screening was investigated by evaluating both autonomic nervous function and subjective levels of fatigue among corporate workers. Based on results from the Brief Job Stress Questionnaire recommended by the research team of the Ministry of Health, Labour and Welfare, 103 participants were divided into two groups (a high-stress group [n = 17] and a non–high-stress group [n = 86]). Visual analog scale (VAS) scores for all fatigue-related symptoms were significantly higher among the high-stress than among the non–high-stress group (p < 0.01).

The mean standard score for autonomic nervous activity was 56.3 for the non–high-stress group. The score for the high-stress group was significantly lower, at 47.9 (p < 0.01), indicating that autonomic nervous function was reduced among participants who experienced high stress. According to an analysis of raw and standard scores in each domain, autonomic nervous activity did not significantly correlate with stress-causing factors (e.g., overwork) or other factors affecting stress responses (e.g., support from supervisors and colleagues), but did exhibit a significant positive correlation with physical and mental responses to stress (r = 0.334, p < 0.01). Lower raw scores for mental and physical responses to stress represent stronger subjective symptoms. Moreover, greater stress responses were found to be associated with lower standard scores for autonomic nervous activity.

In terms of fatigue-related symptoms rated using the VAS, autonomic nervous activity negatively correlated with mental stress, physical stress, fatigue/malaise, depressed mood, anxiety/fear, tension, irritation/anger, cognitive decline, and muscle/joint/general pain, and positively correlated with motivation/vitality. Reduced autonomic nervous activity was observed with high stress, confirming that standard scores for autonomic nervous activity are associated with mental and physical responses to stress and subjective fatigue-related symptoms.

These results indicate that the evaluation of autonomic nervous activity using standard scores (deviation value) is a useful tool for the objective measurement of fatigue state, even in groups with members of different ages, and can be applied as a useful objective health index to evaluate industrial fatigue.

Cortical hypoactivation during resting EEG suggests central nervous system pathology in patients with chronic fatigue syndrome

We investigated central fatigue in 50 patients with chronic fatigue syndrome (CFS) and 50 matched healthy controls (HC). Resting state EEG was collected from 19 scalp locations during a 3 min, eyes-closed condition. Current densities were localized using exact low-resolution electromagnetic tomography (eLORETA). The Multidimensional Fatigue Inventory (MFI-20) and the Fatigue Severity Scale (FSS) were administered to all participants. Independent t-tests and linear regression analyses were used to evaluate group differences in current densities, followed by statistical non-parametric mapping (SnPM) correction procedures. Significant differences were found in the delta (1-3 Hz) and beta-2 (19-21 Hz) frequency bands. Delta sources were found predominately in the frontal lobe, while beta-2 sources were found in the medial and superior parietal lobe. Left-lateralized, frontal delta sources were associated with a clinical reduction in motivation. The implications of abnormal cortical sources in patients with CFS are discussed.

Glial Activation and Expression of the Serotonin Transporter in Chronic Fatigue Syndrome

Fatigue is commonly reported in a variety of illnesses and has major impact on quality of life. Chronic fatigue syndrome (CFS) is a debilitating syndrome of unknown etiology. The clinical symptoms include problems in neuroendocrine, autonomic, and immune systems. It is becoming clear that the brain is the central regulator of CFS. For example, neuroinflammation, especially induced by activation of microglia and astrocytes, may play a prominent role in the development of CFS, though little is known about molecular mechanisms. Many possible causes of CFS have been proposed. However, in this mini-review, we summarize evidence for a role for microglia and astrocytes in the onset and the maintenance of immunologically induced CFS. In a model using virus mimicking synthetic double-stranded RNA, infection causes sequential signaling such as increased blood brain barrier (BBB) permeability, microglia/macrophage activation through Toll-like receptor 3 (TLR3) signaling, secretion of IL-1β, upregulation of the serotonin transporter (5-HTT) in astrocytes, reducing extracellular serotonin (5-HT) levels and hence reduced activation of 5-HT_1A receptor subtype. Hopefully, drug discovery targeting these pathways may be effective for CFS therapy.

CNS findings in chronic fatigue syndrome and a neuropathological case report

Chronic fatigue syndrome (CFS) is characterized as a persistent, debilitating complex disorder of unknown etiology, whereby patients suffer from extreme fatigue, which often presents with symptoms that include chronic pain, depression, weakness, mood disturbances, and neuropsychological impairment. In this mini review and case report, we address central nervous system (CNS) involvement of CFS and present neuropathological autopsy findings from a patient who died with a prior diagnosis of CFS. Among the most remarkable pathological features of the case are focal areas of white matter loss, neurite beading, and neuritic pathology of axons in the white matter with axonal spheroids. Atypical neurons displaying aberrant sprouting processes in response to injury are observed throughout cortical gray and white matter. Abundant amyloid deposits identical to AD plaques with accompanying intracellular granular structures are observed as well. Neurofibrillary tangles are also present in the white matter of the frontal cortex, thalamus and basal ganglia. Taken together, these neuropathological findings warrant further studies into CNS disease associated with CFS.

Increase in the Regional Cerebral Blood Flow following Waon Therapy in Patients with Chronic Fatigue Syndrome: A Pilot Study

Objective Chronic fatigue syndrome (CFS) is a complex disorder, with no consensus on therapeutic options. However, Waon therapy has been reported to be an effective treatment. The purpose of this study was to evaluate changes in the cerebral blood flow (CBF) before and after Waon therapy in CFS patients and to investigate the correlation between such changes and the therapeutic efficacy of Waon therapy. Methods Eleven patients (2 men and 9 women, mean age 27 years old) diagnosed with CFS participated in the study. The disease duration was 8-129 months, and the performance status was 5-8 (on a scale of 0-9). All patients underwent CBF scintigraphy using brain single-photon emission computed tomography (SPECT) with technetium-99m ethyl cysteinate dimer (^99mTc-ECD) before and after Waon therapy. CBF changes after Waon therapy were evaluated using a statistical analysis of imaging data, which was performed with a statistical parametric mapping software program (SPM5). Results Waon therapy reduced symptoms in all 11 patients. We also observed an increase in the CBF within the prefrontal region, orbitofrontal region, and right temporal lobe. These results indicated that an improvement in clinical symptoms was linked to an increase in the CBF. Conclusion The results indicated abnormalities of the cerebral function in the prefrontal region, orbitofrontal region, and right temporal lobe in CFS patients and that Waon therapy improved the cerebral function and symptoms in CFS patients by increasing the regional CBF. To our knowledge, this is the first report to clarify the CBF changes in CFS patients before and after Waon therapy.

High-frequency rTMS for the Treatment of Chronic Fatigue Syndrome: A Case Series

Structural and functional abnormalities of the prefrontal cortex seem to correlate with fatigue in patients with chronic fatigue syndrome (CFS). We consecutively applied facilitatory high-frequency repetitive transcranial magnetic stimulation (rTMS) to the dorsolateral prefrontal cortex (DLPFC) of seven CFS patients over three days. Five patients completed the 3-day protocol without any adverse events. For the other two patients, we had to reduce the stimulation intensity in response to mild adverse reactions. In most of the patients, treatment resulted in an improvement of fatigue symptoms. High-frequency rTMS applied over the DLPFC can therefore be a potentially useful therapy for CFS patients.

Electroencephalogram characteristics in patients with chronic fatigue syndrome

OBJECTIVE

To explore the electroencephalogram (EEG) characteristics in patients with chronic fatigue syndrome (CFS) using brain electrical activity mapping (BEAM) and EEG nonlinear dynamical analysis.

METHODS

Forty-seven outpatients were selected over a 3-month period and divided into an observation group (24 outpatients) and a control group (23 outpatients) by using the non-probability sampling method. All the patients were given a routine EEG. The BEAM and the correlation dimension changes were analyzed to characterize the EEG features.

RESULTS

1) BEAM results indicated that the energy values of δ, θ, and α1 waves significantly increased in the observation group, compared with the control group (P<0.05, P<0.01, respectively), which suggests that the brain electrical activities in CFS patients were significantly reduced and stayed in an inhibitory state; 2) the increase of δ, θ, and α1 energy values in the right frontal and left occipital regions was more significant than other encephalic regions in CFS patients, indicating the region-specific encephalic distribution; 3) the correlation dimension in the observation group was significantly lower than the control group, suggesting decreased EEG complexity in CFS patients.

CONCLUSION

The spontaneous brain electrical activities in CFS patients were significantly reduced. The abnormal changes in the cerebral functions were localized at the right frontal and left occipital regions in CFS patients.

The role of the hippocampus in the pathogenesis of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a severe acquired illness characterized by a profound sensation of fatigue, not ameliorated by rest and resulting in a substantial decrease in the amount and quality of occupational, social and recreational activities. Despite intense research, the aetiology and pathogenesis of ME/CFS is still unknown and no conclusive biological markers have been found. As a consequence, an accepted curative treatment is still lacking and rehabilitation programmes are not very effective, as few patients recover. Increased knowledge of the mechanisms leading to the emergence and maintenance of the illness is called for. In this study, I will put forth an alternative hypothesis to explain some of the pathologies associated with ME/CFS, by concentrating on one of the major strategic organs of the brain, the hippocampus. I will show that the ME/CFS triggering factors also impact the hippocampus, leading to neurocognitive deficits and disturbances in the regulation of the stress system and pain perception. These deficits lead to a substantial decrease in activity and to sleep disorders, which, in turn, impact the hippocampus and initiate a vicious circle of increased disability.

Frontier studies on fatigue, autonomic nerve dysfunction, and sleep-rhythm disorder

Fatigue is defined as a condition or phenomenon of decreased ability and efficiency of mental and/or physical activities, caused by excessive mental or physical activities, diseases, or syndromes. It is often accompanied by a peculiar sense of discomfort, a desire to rest, and reduced motivation, referred to as fatigue sensation. Acute fatigue is a normal condition or phenomenon that disappears after a period of rest; in contrast, chronic fatigue, lasting at least 6 months, does not disappear after ordinary rest. Chronic fatigue impairs activities and contributes to various medical conditions, such as cardiovascular disease, epileptic seizures, and death. In addition, many people complain of chronic fatigue. For example, in Japan, more than one third of the general adult population complains of chronic fatigue. It would thus be of great value to clarify the mechanisms underlying chronic fatigue and to develop efficient treatment methods to overcome it. Here, we review data primarily from behavioral, electrophysiological, and neuroimaging experiments related to neural dysfunction as well as autonomic nervous system, sleep, and circadian rhythm disorders in fatigue. These data provide new perspectives on the mechanisms underlying chronic fatigue and on overcoming it.

Less efficient and costly processes of frontal cortex in childhood chronic fatigue syndrome

The ability to divide one's attention deteriorates in patients with childhood chronic fatigue syndrome (CCFS). We conducted a study using a dual verbal task to assess allocation of attentional resources to two simultaneous activities (picking out vowels and reading for story comprehension) and functional magnetic resonance imaging. Patients exhibited a much larger area of activation, recruiting additional frontal areas. The right middle frontal gyrus (MFG), which is included in the dorsolateral prefrontal cortex, of CCFS patients was specifically activated in both the single and dual tasks; this activation level was positively correlated with motivation scores for the tasks and accuracy of story comprehension. In addition, in patients, the dorsal anterior cingulate gyrus (dACC) and left MFG were activated only in the dual task, and activation levels of the dACC and left MFG were positively associated with the motivation and fatigue scores, respectively. Patients with CCFS exhibited a wider area of activated frontal regions related to attentional resources in order to increase their poorer task performance with massive mental effort. This is likely to be less efficient and costly in terms of energy requirements. It seems to be related to the pathophysiology of patients with CCFS and to cause a vicious cycle of further increases in fatigue.

•

Decrease in divided attention was related to fatigue in childhood and adolescence.

•

Left frontal cortex of healthy students activated in verbal divided attention task

•

Right MFG and ACG were additionally activated in CCFS patients.

•

CCFS is characterized as an energy-inefficient process in frontal cortex.

Bioanalysis of acetylcarnitine in cerebrospinal fluid by HILIC-mass spectrometry

Acetyl-L-carnitine (ALCAR) is a potential biomarker for the modulation of brain neurotransmitter activity, but is also present in cerebrospinal fluid (CSF). Recent studies have utilized hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS) based assays to detect and quantify ALCAR within biofluids such as urine, plasma and serum, using various sample pretreatment procedures. In order to address the need to quantify ALCAR in CSF on a high-throughput scale, a new and simple HILIC-MS/MS assay has been successfully developed and validated. For rapid analysis, CSF sample pretreatment was performed via 'dilute and shoot' directly onto an advanced HILIC column prior to MS/MS detection. This newly developed HILIC-MS/MS assay shows good recoveries of ALCAR without the need for chemical derivatization and multistep sample extraction procedures. The employment of this assay is suitable for the high-throughput bioanalysis and quantification of ALCAR within the CSF of various animal models and human clinical studies.

Myalgic Encephalomyelitis: Symptoms and Biomarkers

Myalgic Encephalomyelitis (ME) continues to cause significant morbidity worldwide with an estimated one million cases in the United States. Hurdles to establishing consensus to achieve accurate evaluation of patients with ME continue, fueled by poor agreement about case definitions, slow progress in development of standardized diagnostic approaches, and issues surrounding research priorities. Because there are other medical problems, such as early MS and Parkinson's Disease, which have some similar clinical presentations, it is critical to accurately diagnose ME to make a differential diagnosis. In this article, we explore and summarize advances in the physiological and neurological approaches to understanding, diagnosing, and treating ME. We identify key areas and approaches to elucidate the core and secondary symptom clusters in ME so as to provide some practical suggestions in evaluation of ME for clinicians and researchers. This review, therefore, represents a synthesis of key discussions in the literature, and has important implications for a better understanding of ME, its biological markers, and diagnostic criteria. There is a clear need for more longitudinal studies in this area with larger data sets, which correct for multiple testing.

Neural effect of mental fatigue on physical fatigue: a magnetoencephalography study

We sought to clarify the neural effect of mental fatigue on physical fatigue using magnetoencephalography (MEG) and classical conditioning techniques. Eleven right-handed volunteers participated in this study. On the first day, participants performed fatigue-inducing maximum handgrip trials for 10 min; metronome sounds were started 5 min after the beginning of the trials. We used metronome sounds as conditioned stimuli and maximum handgrip trials as unconditioned stimuli to cause physical fatigue. On the next day, MEG recordings during the imagery of maximum grips of the right hand guided by the metronome sounds were performed for 10 min just before (control session) and after (mental fatigue session) a 30-min fatigue-inducing mental task session. In the right anterior cingulate cortex (Brodmann's area 23), the alpha-band event-related synchronization of the mental fatigue session relative to the control session within the time window of 500–600 ms after the onset of handgrip cue sounds was identified. We demonstrated that mental fatigue suppresses activities in the right anterior cingulate cortex during physical fatigue.

Induction of interleukin-1β by activated microglia is a prerequisite for immunologically induced fatigue

We previously reported that an intraperitoneal (i.p.) injection of synthetic double-stranded RNA, polyriboinosinic:polyribocytidylic acid (poly-I:C), produced prolonged fatigue in rats, which might serve as a model for chronic fatigue syndrome. The poly-I:C-induced fatigue was associated with serotonin transporter (5-HTT) overexpression in the prefrontal cortex (PFC), a brain region that has been suggested to be critical for fatigue sensation. In the present study, we demonstrated that microglial activation in the PFC was important for poly-I:C-induced fatigue in rats, as pretreatment with minocycline, an inhibitor of microglial activation, prevented the decrease in running wheel activity. Poly-I:C injection increased the microglial interleukin (IL)-1β expression in the PFC. An intracerebroventricular (i.c.v.) injection of IL-1β neutralising antibody limited the poly-I:C-induced decrease in activity, whereas IL-1β (i.c.v.) reduced the activity in a dose-dependent manner. 5-HTT expression was enhanced by IL-1β in primary cultured astrocytes but not in microglia. Poly-I:C injection (i.p.) caused an increase in 5-HTT expression in astrocytes in the PFC of the rat, which was inhibited by pretreatment with minocycline (i.p.) and rat recombinant IL-1 receptor antagonist (i.c.v.). Poly-I:C injection (i.p.) led to a breakdown of the blood-brain barrier and enhanced Toll-like receptor 3 signaling in the brain. Furthermore, direct application of poly-I:C enhanced IL-1β expression in primary microglia. We therefore propose that poly-I:C-induced microglial activation, which may be at least partly caused by a direct action of poly-I:C, enhances IL-1β expression. Then, IL-1β induces 5-HTT expression in astrocytes, resulting in the immunologically induced fatigue.

Considerations in establishing a post-mortem brain and tissue bank for the study of myalgic encephalomyelitis/chronic fatigue syndrome: a proposed protocol

BACKGROUND

Our aim, having previously investigated through a qualitative study involving extensive discussions with experts and patients the issues involved in establishing and maintaining a disease specific brain and tissue bank for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), was to develop a protocol for a UK ME/CFS repository of high quality human tissue from well characterised subjects with ME/CFS and controls suitable for a broad range of research applications. This would involve a specific donor program coupled with rapid tissue collection and processing, supplemented by comprehensive prospectively collected clinical, laboratory and self-assessment data from cases and controls.

FINDINGS

We reviewed the operations of existing tissue banks from published literature and from their internal protocols and standard operating procedures (SOPs). On this basis, we developed the protocol presented here, which was designed to meet high technical and ethical standards and legal requirements and was based on recommendations of the MRC UK Brain Banks Network. The facility would be most efficient and cost-effective if incorporated into an existing tissue bank. Tissue collection would be rapid and follow robust protocols to ensure preservation sufficient for a wide range of research uses. A central tissue bank would have resources both for wide-scale donor recruitment and rapid response to donor death for prompt harvesting and processing of tissue.

CONCLUSION

An ME/CFS brain and tissue bank could be established using this protocol. Success would depend on careful consideration of logistic, technical, legal and ethical issues, continuous consultation with patients and the donor population, and a sustainable model of funding ideally involving research councils, health services, and patient charities. This initiative could revolutionise the understanding of this still poorly-understood disease and enhance development of diagnostic biomarkers and treatments.

Neural mechanisms underlying chronic fatigue

Fatigue is defined as a condition or phenomenon of declined ability and efficiency of mental and/or physical activities, caused by excessive mental or physical activities, diseases, or syndromes. Acute fatigue is a normal condition that disappears after a period of rest; in contrast, chronic fatigue does not disappear after an ordinary rest. Chronic fatigue impairs daily activities and contributes to various medical conditions and death. In addition, many people complain of chronic fatigue. It would thus be of great value to clarify the mechanisms underlying chronic fatigue and to develop efficient treatment methods to overcome it. Here, we review data primarily from behavioral, neurophysiological, and neuroimaging experiments related to the neural mechanisms underlying chronic fatigue. We propose that repetitive and prolonged overwork and/or stress cause neural damage of a facilitation system, as well as central sensitization and classical conditioning of an inhibition system. We also propose a new treatment strategy for chronic fatigue on the basis of its underlying neural mechanisms.

Neuroinflammation in Patients with Chronic Fatigue Syndrome/Myalgic Encephalomyelitis: An ¹¹C-(R)-PK11195 PET Study

Chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) is a disease characterized by chronic, profound, disabling, and unexplained fatigue. Although it is hypothesized that brain inflammation is involved in the pathophysiology of CFS/ME, there is no direct evidence of neuroinflammation in patients with CFS/ME. Activation of microglia or astrocytes is related to neuroinflammation. (11)C-(R)-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinoline-carboxamide ((11)C-(R)-PK11195) is a ligand of PET for a translocator protein that is expressed by activated microglia or astrocytes. We used (11)C-(R)-PK11195 and PET to investigate the existence of neuroinflammation in CFS/ME patients.

METHODS

Nine CFS/ME patients and 10 healthy controls underwent (11)C-(R)-PK11195 PET and completed questionnaires about fatigue, fatigue sensation, cognitive impairments, pain, and depression. To measure the density of translocator protein, nondisplaceable binding potential (BP(ND)) values were determined using linear graphical analysis with the cerebellum as a reference region.

RESULTS

The BP(ND) values of (11)C-(R)-PK11195 in the cingulate cortex, hippocampus, amygdala, thalamus, midbrain, and pons were 45%-199% higher in CFS/ME patients than in healthy controls. In CFS/ME patients, the BP(ND) values of (11)C-(R)-PK11195 in the amygdala, thalamus, and midbrain positively correlated with cognitive impairment score, the BP(ND) values in the cingulate cortex and thalamus positively correlated with pain score, and the BP(ND) value in the hippocampus positively correlated with depression score.

CONCLUSION

Neuroinflammation is present in widespread brain areas in CFS/ME patients and was associated with the severity of neuropsychologic symptoms. Evaluation of neuroinflammation in CFS/ME patients may be essential for understanding the core pathophysiology and for developing objective diagnostic criteria and effective medical treatments.

Regulatory mechanism of performance in chronic cognitive fatigue

Chronic cognitive fatigue is characterized by a sensation of long-lasting fatigue that impairs cognitive functions. Facilitation and inhibition systems in the central nervous system play primary roles in determining the output to the peripheral system, that is, performance. Sensory input from the peripheral system to the central nervous system activates the inhibition system to limit performance, whereas motivational input activates the facilitation system to enhance performance. The dysfunction of the facilitation system and central sensitization and classical conditioning of the inhibition system play important roles in the pathophysiology of chronic cognitive fatigue. Because the dorsolateral prefrontal cortex receives input from both the facilitation and inhibition systems to determine performance, metabolic, functional, and structural impairments of the dorsolateral prefrontal cortex induced by repetitive and prolonged overwork, stress, and stress responses contribute to the impaired functioning and cognitive performance that occur in people with chronic cognitive fatigue. This hypothesis of the regulatory mechanism of performance provides a new perspective on the neural mechanisms underlying chronic cognitive fatigue.

Autonomic nervous alterations associated with daily level of fatigue

BACKGROUND

Fatigue is a common symptom in both sick and healthy people. We examined autonomic nervous alterations associated with fatigue to clarify the mechanisms underlying fatigue.

METHODS

The study group consisted of 19 healthy participants who performed a 2-back test for 30 min as a fatigue-inducing mental task session. Before and after the session, they completed the advanced trail making test (ATMT) for 30 min for mental fatigue evaluation, subjective scales to measure fatigue sensation, and underwent electrocardiography to allow assessment of autonomic nerve activities.

RESULTS

After the fatigue-inducing task, the total error counts on the ATMT tended to increase (P = 0.076); the ATMT for total trial counts (P = 0.001), the subjective level of fatigue (P < 0.001), and the % low-frequency power (%LF) (P = 0.035) increased significantly; and the % high-frequency power (%HF) decreased compared with before the fatigue-inducing task although this did not reach the statistical significance (P = 0.170). Although LF measured in absolute units did not change significantly before and after the fatigue-inducing task (P = 0.771), and HF measured in absolute units decreased after the task (P = 0.020). The %LF and LF/HF ratio were positively associated with the daily level of fatigue evaluated using Chalder's fatigue scale. In addition, %HF was negatively associated with the fatigue score.

CONCLUSIONS

Increased sympathetic activity and decreased parasympathetic activity may be characteristic features of both acute and daily levels of fatigue. Our findings provide new perspectives on the mechanisms underlying fatigue.

Quantitative tandem mass spectrometric imaging of endogenous acetyl-L-carnitine from piglet brain tissue using an internal standard

Matrix-assisted laser desorption/ionization (MALDI) based mass spectrometric imaging (MSI) is increasingly being used as an analytical tool to evaluate the molecular makeup of tissue samples. From the direct analysis of a tissue section, the physical integrity of sample is preserved; thus, spatial information of a compound's distribution may be determined. One limitation of the technique, however, has been the inability to determine the absolute concentration from a tissue sample. Here we report the development of a quantitative MSI technique in which the distribution of acetyl-L-carnitine (AC) in a piglet brain sample is quantified with MALDI MSI. An isotopically labeled internal standard was applied uniformly beneath the tissue section, and wide-isolation tandem mass spectrometry was performed. Normalizing the analyte ion signal by the internal standard ion signal resulted in significant improvements in MS images, signal reproducibility, and calibration curve linearity. From the improved MS images, the concentration of AC was determined and plotted producing a concentration-scaled image of the distribution of AC in the piglet brain section.

Cerebral blood flow is reduced in chronic fatigue syndrome as assessed by arterial spin labeling

BACKGROUND

Chronic fatigue syndrome is diagnosed by a set of clinical criteria and therefore is probably heterogeneous. Earlier reports tested the hypothesis that the syndrome had a neurological substrate by doing studies of cerebral blood flow (CBF) but with discrepant results. One possible reason for the discrepancy was that relative CBF was assessed. We found reduced CBF in an earlier study of absolute CBF using xenon-CT. The purpose of this study was to use a second method of assessing CBF and to look within the study group for heterogeneity of responses.

METHOD

Eleven CFS patients and 10 age matched healthy controls underwent neuroimaging using arterial spin labeling to determine their regional and global absolute CBF. A template was constructed based on the control data, and individual patient montages were compared on a case by case basis to determine if differences in regions of interest occurred.

RESULTS

The patients as a group had significantly lower global CBF than the controls. The reduction in CBF occurred across nearly every region assessed. Nine of the 11 patients showed these reductions compared to the average control data, while two patients showed actual increases relative to the controls.

CONCLUSION

The data extend our earlier observation that CFS patients as a group have broad decreases in CBF compared to healthy controls. However, as expected, the effect was not homogeneous in that 2 of the 11 patients studied showed actual increases in CBF relative to controls.

The increase of alpha-melanocyte-stimulating hormone in the plasma of chronic fatigue syndrome patients

Background

Despite extensive research, no reliable biological marker for chronic fatigue syndrome (CFS) has yet been identified. However, hyperactivation of melanotrophs in the pituitary gland and increased levels of plasma alpha-melanocyte-stimulating hormone (α-MSH) have recently been detected in an animal model of chronic stress. Because CFS is considered to be caused partly by chronic stress events, increased α-MSH plasma levels may also occur in CFS patients. We therefore examined α-MSH levels in CFS patients.

Methods

Fifty-five CFS patients, who were previously diagnosed within 10 years of with the disease, were enrolled in this study. Thirty healthy volunteers were studied as controls. Fasting bloods samples were collected in the morning and evaluated for their plasma levels of α-MSH, adrenocorticotropic hormone (ACTH), serum cortisol and dehydroepiandrosterone sulfate (DHEA-S). Mean levels of α-MSH were compared between the CFS and control groups using Welch's t test.

Results

The mean plasma α-MSH concentration in the CFS group (17.9 ± 1.0 pg/mL) was significantly higher than that in healthy controls (14.5 ± 1.0 pg/mL, p = 0.02). However, there was a wide range of values in the CFS group. The factors correlated with the plasma α-MSH values were analyzed using Spearman's rank correlation. A negative correlation was found between the duration of the CFS and the plasma α-MSH values (p = 0.04, r_s = -0.28), but no correlations with ACTH, cortisol or DHEA-S levels were identified (p = 0.55, 0.26, 0.33, respectively). The CFS patients were divided into two groups: patients diagnosed for ≤ 5 years' duration, and those diagnosed for 5-10 years' duration. They were compared with the healthy controls using one-way ANOVA and Tukey-Kramer multiple comparison tests. The mean α-MSH concentration in the ≤ 5 years group was 20.8 ± 1.2 pg/mL, which was significantly higher than that in the healthy controls (p < 0.01). There was no significant difference between the 5-10 year group (15.6 ± 1.4 pg/mL) and the healthy controls.

Conclusions

CFS patients with a disease duration of ≤ 5 years had significantly higher levels of α-MSH in their peripheral blood. α-MSH could be a potent biological marker for the diagnosis of CFS, at least during the first 5 years after onset of the disease.

Metabolic dysfunction and circadian rhythm abnormalities in adolescents with sleep disturbance

BACKGROUND

Sleep disturbance attributable to circadian rhythm abnormalities frequently occurs in previously healthy children and adolescents who often complain of gastrointestinal discomfort after meals.

METHODS

Glucose metabolism, autonomic function, and human clock gene expression in whole blood cells were investigated in 18 adolescent patients with circadian rhythm sleep disorder.

RESULTS

Glucose tolerance was significantly lower in the patients than in normal controls: the mean sigma blood glucose level was significantly higher (P<0.05) and the insulinogenic index was significantly lower (P<0.05) in the patient group than in controls. Messenger ribonucleic acid level of hPer2 was significantly higher at 6:00 in the control subjects, but in only 3 of the 18 patients. Component analysis of cardiographic R-R interval revealed that high-frequency component peaks were suppressed significantly in the patient group compared to the controls (P<0.001).

CONCLUSIONS

Metabolic and endocrine dysfunctions were identified in adolescents with sleep disturbance as decreased glucose tolerance and absence of human clock gene regulation in whole blood cells. Their brain dysfunction attributable to sleep disturbances might cause such peripheral autonomic imbalance and carbohydrate metabolic dysfunction.

Subjective feeling of psychological fatigue is related to decreased reactivity in ventrolateral prefrontal cortex

The purpose of this study is to examine the relationship between subjective fatigue and brain function. Twenty-three healthy young volunteers participated in this study. Relationships were investigated between subjective fatigue assessed using visual-analogue scale (VAS) score and sleep duration, and cerebral cortex reactivity during a verbal fluency task by 52-channel near-infrared spectroscopy (NIRS). The VAS score negatively correlated with oxygenated hemoglobin concentration ([oxy-Hb]) increases in the bilateral channels over the regions from the ventrolateral part of the frontal lobe to the upper part of the temporal lobe during the verbal fluency task. Sleep duration in the previous night positively correlated with [oxy-Hb] increases in the bilateral channels over the dorsolateral prefrontal lobe also during the verbal fluency task. No significant correlations between the VAS score and sleep duration in the previous night with [oxy-Hb] increases were found during a control task, the left-finger-tapping task. The subjective feeling of psychological fatigue is related to decreased reactivities in the lateral frontal and superior temporal cortices and is unrelated to sleep duration in the previous night, which is reflected in the reactivity in the dorsolateral prefrontal cortices. These results suggest that transient hypofunction and persistent dysfunction in the lateral prefrontal and temporal lobes are among the brain substrates of fatigue. These also demonstrate the advantage of NIRS for investigating brain function during subjective phenomena such as fatigue because it enables examination in a natural setting.

Fatigue in Advanced Cancer: A Prospective Study

Fatigue is a common advanced cancer symptom. Clinical features are not well known. The authors surveyed consecutive patients admitted to a palliative medicine program to identify clinical correlates of fatigue. Data collected included age, sex, performance status, primary site, prior chemotherapy/radiation therapy, and blood transfusions. Visual analogue scales assessed fatigue, quality of life, and ability to perform daily activities. Weight change was estimated. Laboratory results including lactate dehydrogenase and hemoglobin were recorded. Fatigue severity was associated with brain metastases, poor performance status, poor quality of life, and reduced ability to perform activities. Prior radiation therapy was associated with less severe fatigue. Age, sex, and hemoglobin level were not associated with fatigue. Fatigue was universal on referral. Brain metastases and poor quality of life independently predicted severity. Hemoglobin level did not predict fatigue. Further studies are necessary to define the clinical features and relationships of fatigue.

Management of fatigue in cancer patients

Cancer-related fatigue (CRF) is either a symptom or a syndrome depending on criteria for diagnosis. CRF is present in 20% to 30% of long-term cancer survivors and 80% to 90% during treatment and at the end of life. Assessment requires determining the presence, severity, and interference with daily activities. Different descriptors for fatigue (eg, tiredness, lack of vigor) measure different patient experiences. Associated factors such as depression, pain, insomnia, dyspnea, anemia, and deconditioning worsen CRF and should be treated if present. Associated factors that contribute to the severity of fatigue differ depending on the stage of cancer. Pharmacologic interventions include recombinant erythropoietin, psychostimulants, corticosteroid, anti-inflammatory drugs other than steroids, and L-carnitine. Advances in the management of CRF will require an understanding of the underlying mechanism before target-specific therapies can be developed.

Cloning and functional characterization of a novel up-regulator, cartregulin, of carnitine transporter, OCTN2

Acetylcarnitine exerts therapeutic effects on some neurological disorders including Alzheimer's disease. OCTN2 is known as a transporter for acetylcarnitine, but its expression in the brain is very low. To examine a brain-specific transporter for acetylcarnitine, we screened a rat brain cDNA library by hybridization using a DNA probe conserved among an OCTN family. A cDNA homologous to OCTN2 cDNA was isolated. The cDNA encoded a novel 146-amino acid protein with one putative transmembrane domain. The mRNA was expressed not only in rat brain but also in some other tissues. The novel protein was localized in endoplasmic reticulum when expressed in COS-7 cells but exhibited no transport activity for acetylcarnitine. However, when co-expressed with OCTN2, it enhanced the OCTN2-mediated transport by about twofold. The enhancement was accompanied by an increase in the levels of mRNA and protein. When OCTN2 was expressed in Xenopus oocytes by injection of its cRNA, its transport activity was enhanced by co-expression of the novel protein. These data suggest that the novel protein increases OCTN2 by stabilizing the mRNA in endoplasmic reticulum. The protein may be an up-regulator of OCTN2 and is tentatively designated cartregulin.

The debate: myalgic encephalomyelitis and chronic fatigue syndrome

Almost every aspect of myalgic encephalomyelitis (or encephalopathy) and chronic fatigue syndrome is the subject of disagreement and uncertainty -- something that has undoubtedly hampered recognition, understanding and research. Although the pathogenesis remains the subject of intense medical debate, a number of predisposing, precipitating and perpetuating factors are now starting to emerge. Therapeutic nihilism is no longer appropriate as there is a great deal that can be done to alleviate some of the more distressing symptoms and improve quality of life for these patients.

Spectroscopic diagnosis of chronic fatigue syndrome by visible and near-infrared spectroscopy in serum samples

To investigate visible and near-infrared (Vis-NIR) spectroscopy enabling chronic fatigue syndrome (CFS) diagnosis, we subjected sera from CFS patients as well as healthy donors to Vis-NIR spectroscopy. Vis-NIR spectra in the 600-1100 nm region for sera from 77 CFS patients and 71 healthy donors were subjected to principal component analysis (PCA) and soft independent modeling of class analogy (SIMCA) to develop multivariate models to discriminate between CFS patients and healthy donors. The model was further assessed by the prediction of 99 masked other determinations (54 in the healthy group and 45 in the CFS patient group). The PCA model predicted successful discrimination of the masked samples. The SIMCA model predicted 54 of 54 (100%) healthy donors and 42 of 45 (93.3%) CFS patients of Vis-NIR spectra from masked serum samples correctly. These results suggest that Vis-NIR spectroscopy for sera combined with chemometrics analysis could provide a promising tool to objectively diagnose CFS.

Functional expression of the organic cation/carnitine transporter 2 in rat astrocytes

In this study, we sought to identify the transporters that mediate the uptake of L-carnitine and acetyl-L-carnitine in cultured rat cortical astrocytes. L-[(3)H]carnitine and acetyl-L-[(3)H]carnitine uptake were both saturable, and mediated by a single Na(+)-dependent transport system. Uptake of both was inhibited by L-carnitine, D-carnitine, acetyl-L-carnitine and various organic cations. Acylcarnitines (acetyl-, butyryl-, hexanoyl-, octanoyl- and palmitoyl-L-carnitine) also interacted with L-[(3)H]carnitine and acetyl-L-[(3)H]carnitine transport. 2-Amino-2-norbornane carboxylic acid, a known inhibitor of amino acid transporter B(0,+) (ATB(0,+)), did not cause any significant inhibition. A highly significant correlation was found between the potencies of acylcarnitines in the inhibition of L-[(3)H]carnitine and acetyl-L-[(3)H]carnitine uptake and the acyl chain length of acylcarnitines. The expression of mRNA for organic cation/carnitine transporters (OCTNs), carnitine transporter 2 (CT2) and ATB(0,+) in astrocytes was investigated by reverse transcription (RT)-PCR. OCTN2 mRNA was expressed in astrocytes, whereas the expression of OCTN1, OCTN3 and CT2 mRNA could not be detected. ATB(0,+) mRNA was expressed at very low levels in astrocytes. Western blotting analysis indicated that anti-OCTN2 polyclonal antibody recognized a band of 70 kDa in both kidney and astrocyte preparations. OCTN2 immunoreactivity was detected in rat astrocytes by immunocytochemical staining. Inhibition of OCTN2 expression by RNA interference significantly inhibited L-[(3)H]carnitine and acetyl-L-[(3)H]carnitine uptake into astrocytes. These results suggest that OCTN2 is functionally expressed in rat astrocytes, and is responsible for L-carnitine and acetyl-L-carnitine uptake in these cells.