Single-cell transcriptomics of the immune system in ME/CFS at baseline and following symptom provocation

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a serious and poorly understood disease. To understand immune dysregulation in ME/CFS, we use single-cell RNA sequencing (scRNA-seq) to examine immune cells in patient and control cohorts. Postexertional malaise (PEM), an exacerbation of symptoms following strenuous exercise, is a characteristic symptom of ME/CFS. To detect changes coincident with PEM, we applied scRNA-seq on the same cohorts following exercise. At baseline, ME/CFS patients display classical monocyte dysregulation suggestive of inappropriate differentiation and migration to tissue. We identify both diseased and more normal monocytes within patients, and the fraction of diseased cells correlates with disease severity. Comparing the transcriptome at baseline and postexercise challenge, we discover patterns indicative of improper platelet activation in patients, with minimal changes elsewhere in the immune system. Taken together, these data identify immunological defects present at baseline in patients and an additional layer of dysregulation in platelets.

Recovery from Exercise in Persons with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)

Background and Objectives: Post-exertional malaise (PEM) is the hallmark of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), but there has been little effort to quantitate the duration of PEM symptoms following a known exertional stressor. Using a Symptom Severity Scale (SSS) that includes nine common symptoms of ME/CFS, we sought to characterize the duration and severity of PEM symptoms following two cardiopulmonary exercise tests separated by 24 h (2-day CPET). Materials and Methods: Eighty persons with ME/CFS and 64 controls (CTL) underwent a 2-day CPET. ME/CFS subjects met the Canadian Clinical Criteria for diagnosis of ME/CFS; controls were healthy but not participating in regular physical activity. All subjects who met maximal effort criteria on both CPETs were included. SSS scores were obtained at baseline, immediately prior to both CPETs, the day after the second CPET, and every two days after the CPET-1 for 10 days. Results: There was a highly significant difference in judged recovery time (ME/CFS = 12.7 ± 1.2 d; CTL = 2.1 ± 0.2 d, mean ± s.e.m., Chi2 = 90.1, p < 0.0001). The range of ME/CFS patient recovery was 1–64 days, while the range in CTL was 1–10 days; one subject with ME/CFS had not recovered after one year and was not included in the analysis. Less than 10% of subjects with ME/CFS took more than three weeks to recover. There was no difference in recovery time based on the level of pre-test symptoms prior to CPET-1 (F = 1.12, p = 0.33). Mean SSS scores at baseline were significantly higher than at pre-CPET-1 (5.70 ± 0.16 vs. 4.02 ± 0.18, p < 0.0001). Pharmacokinetic models showed an extremely prolonged decay of the PEM response (Chi2 > 22, p < 0.0001) to the 2-day CPET. Conclusions: ME/CFS subjects took an average of about two weeks to recover from a 2-day CPET, whereas sedentary controls needed only two days. These data quantitate the prolonged recovery time in ME/CFS and improve the ability to obtain well-informed consent prior to doing exercise testing in persons with ME/CFS. Quantitative monitoring of PEM symptoms may provide a method to help manage PEM.

Plasma metabolomics reveals disrupted response and recovery following maximal exercise in myalgic encephalomyelitis/chronic fatigue syndrome

Post-exertional malaise (PEM) is a hallmark symptom of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). We monitored the evolution of 1157 plasma metabolites in 60 ME/CFS (45 female, 15 male) and 45 matched healthy control participants (30 female, 15 male) before and after 2 maximal cardiopulmonary exercise test (CPET) challenges separated by 24 hours, with the intent of provoking PEM in patients. Four time points allowed exploration of the metabolic response to maximal energy-producing capacity and the recovery pattern of participants with ME/CFS compared with the healthy control group. Baseline comparison identified several significantly different metabolites, along with an enriched percentage of yet-to-be identified compounds. Additionally, temporal measures demonstrated an increased metabolic disparity between cohorts, including unknown metabolites. The effects of exertion in the ME/CFS cohort predominantly highlighted lipid-related as well as energy-related pathways and chemical structure clusters, which were disparately affected by the first and second exercise sessions. The 24-hour recovery period was distinct in the ME/CFS cohort, with over a quarter of the identified pathways statistically different from the controls. The pathways that are uniquely different 24 hours after an exercise challenge provide clues to metabolic disruptions that lead to PEM. Numerous altered pathways were observed to depend on glutamate metabolism, a crucial component of the homeostasis of many organs in the body, including the brain.

Eukaryotes in the gut microbiota in myalgic encephalomyelitis/chronic fatigue syndrome

Patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) often suffer from gastrointestinal symptoms and many are diagnosed with irritable bowel syndrome (IBS). Previous studies, including from our laboratory, have demonstrated that the ME/CFS gut bacterial composition is altered and less diverse when compared to healthy individuals. Patients have increased biomarkers of inflammation and leaky gut syndrome. To further investigate dysbiosis in the ME/CFS gut microbiome, we sought to characterize the eukaryotes present in the gut of 49 individuals with ME/CFS and 39 healthy controls. Using 18S rRNA sequencing, we have identified eukaryotes in stool samples of 17 healthy individuals and 17 ME/CFS patients. Our analysis demonstrates a small, nonsignificant decrease in eukaryotic diversity in ME/CFS patients compared to healthy individuals. In addition, ME/CFS patients show a nonsignificant increase in the ratio of fungal phyla Basidiomycota to Ascomycota, which is consistent with ongoing inflammation in ME/CFS. We did not identify specific eukaryotic taxa that are associated with ME/CFS disease status.

A Pair of Identical Twins Discordant for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Differ in Physiological Parameters and Gut Microbiome Composition

Patient: Male, 34

Final Diagnosis: ME/CFS

Symptoms: Exertion intolerance • loss of functional capacity • pain • severe fatigue

Medication: —

Clinical Procedure: Cardiopulmonary exercise test

Specialty: Sports Medicine

Fetal surgery for myelomeningocele: history, research, clinical trials, and future directions

Myelomeningocele, more commonly known as spina bifida, is the most common neural tube defect worldwide. In the United States, it is the primary cause of lifelong childhood paralysis with approximately four children born daily with this devastating disease. To minimize damage to the exposed spinal cord and prevent ascending central nervous system infections, postnatal closure of the spinal defect has been the standard of care for decades. Research into the mechanism of spinal cord injury in those with spina bifida revealed that damage continues to accrue during the gestational period. Prenatal defect closure via in utero surgery was proposed to prevent this early deterioration of the spinal cord, and early animal research demonstrated that prenatal repair was feasible and promising. This paved the way for the first human prenatal repairs in the mid-to-late 1990s. Following the promising outcomes observed during the first human cases, a randomized controlled trial, the Management of Myelomeningocele Study (MOMS), was conducted comparing postnatal repair of spina bifida to prenatal repair. The MOMS trial demonstrated that to those undergoing prenatal repair of spina bifida had a decreased need for ventriculoperitoneal shunting and improved lower extremity motor function. With the success of the MOMS trial, in utero repair is now considered the standard of care in those who meet the criteria for prenatal repair. This review will provide an overview of spina bifida and its impact, highlight the historical changes in care, describe the early research and theory that made prenatal repair an option, discuss the clinical experiences with human fetal repair and briefly touch on future research directions for those with myelomeningocele.

Inability of myalgic encephalomyelitis/chronic fatigue syndrome patients to reproduce VO₂peak indicates functional impairment

BACKGROUND

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a multi-system illness characterized, in part, by increased fatigue following minimal exertion, cognitive impairment, poor recovery to physical and other stressors, in addition to other symptoms. Unlike healthy subjects and other diseased populations who reproduce objective physiological measures during repeat cardiopulmonary exercise tests (CPETs), ME/CFS patients have been reported to fail to reproduce results in a second CPET performed one day after an initial CPET. If confirmed, a disparity between a first and second CPET could serve to identify individuals with ME/CFS, would be able to document their extent of disability, and could also provide a physiological basis for prescribing physical activity as well as a metric of functional impairment.

METHODS

22 subjects diagnosed with ME/CFS completed two repeat CPETs separated by 24 h. Measures of oxygen consumption (VO₂), heart rate (HR), minute ventilation (Ve), workload (Work), and respiratory exchange ratio (RER) were made at maximal (peak) and ventilatory threshold (VT) intensities. Data were analyzed using ANOVA and Wilcoxon's Signed-Rank Test (for RER).

RESULTS

ME/CFS patients showed significant decreases from CPET1 to CPET2 in VO₂peak (13.8%), HRpeak (9 bpm), Ve peak (14.7%), and Work@peak (12.5%). Decreases in VT measures included VO₂@VT (15.8%), Ve@VT (7.4%), and Work@VT (21.3%). Peak RER was high (≥1.1) and did not differ between tests, indicating maximum effort by participants during both CPETs. If data from only a single CPET test is used, a standard classification of functional impairment based on VO₂peak or VO₂@VT results in over-estimation of functional ability for 50% of ME/CFS participants in this study.

CONCLUSION

ME/CFS participants were unable to reproduce most physiological measures at both maximal and ventilatory threshold intensities during a CPET performed 24 hours after a prior maximal exercise test. Our work confirms that repeated CPETs warrant consideration as a clinical indicator for diagnosing ME/CFS. Furthermore, if based on only one CPET, functional impairment classification will be mis-identified in many ME/CFS participants.

State of the Art Reviews: Development of Fitness in Children: The Influence of Gender and Physical Activity

The influences of gender and physical activity on the development of fitness are reviewed from early childhood to late adolescence. Changes in parameters of fitness prior to puberty are driven predominantly by neuroendocrine-mediated factors, although physical activity level may be influenced largely by sociocultural factors prior to and following puberty. Thus, it is still unclear to what extent environment versus genetics accounts for gender differences in fitness. Future studies need to account for all factors known to explain gender differences in fitness to better differentiate intrinsic versus environmental causes. Consequently, one must consider if and to what extent a gender comparison study actually reveals true, inherent gender differences compared with sociocultural and/or cultural influences. Nevertheless, differences in fitness between girls and boys that are influenced by sociocultural factors should be considered when devising programs to promote physical activity and enhance fitness in youth. Fundamentally, the role of parents and primary caregivers in modeling physical activity and influencing the fitness level of their child cannot be overestimated.

Effects of meal form and composition on plasma testosterone, cortisol, and insulin following resistance exercise

The purpose of this study was to examine the effects of postexercise feeding on plasma levels of insulin, testosterone, cortisol, and testosterone:cortisol (T:C). Ten experienced, resistance trained males (20.7 +/- 0.95 years) were given whole food (WF: protein 38 g; carbohydrate 70 g; fat 7 g), a supplemental drink (SD; isocaloric and isonitrogenous to WF), an isocaloric carbohydrate beverage (C), or a placebo beverage (P) immediately, 2 and 4 hours after a standardized weight training protocol on 4 days, each separated by 1 week, in a repeated measures design. Subjects also received a standardized meal at 7 and 12 hours postexercise. Insulin, testosterone, and cortisol were measured pre-exercise and during 24 hours of recovery (at 0.5, 2.5, 4.5, 8, and 24 hours) using venous blood samples. Significant (condition 3 time) interactions were found for insulin, testosterone, and T:C, but not for cortisol (p <. 05). The SD yielded a greater response for insulin than all other conditions. Conversely, P demonstrated the greatest values for testosterone and T:C at 2.5 and 4.5 hours postexercise. Cortisol did not vary between conditions and there were no condition effects for insulin, testosterone, cortisol, and T:C at 8 or 24 hours. In conclusion, the efficacy of postexercise feeding for optimizing T:C and muscle growth is unclear; however, consumption of SD appears to maximize circulating insulin for several hours following resistance exercise.

Mutations at arg486 and glu571 in human topoisomerase IIalpha confer resistance to amsacrine: relevance for antitumor drug resistance in human cells

Human topoisomerase II, a nuclear protein involved in chromosome segregation, is the target of amsacrine and other clinically important anticancer drugs. The enzyme is expressed as alpha and beta isoforms whose mutation/down-regulation has been implicated in drug resistance. To understand the role of target mutations in cellular drug resistance, we have used yeast to select and characterize plasmid-borne human topoisomerase IIalpha mutants resistant to amsacrine. Single point changes of Glu571 to Lys (E571K) or Arg486 to Lys (R486K) in the conserved PLRGK motif, both of which reside in the GyrB homology domain of human topoisomerase IIalpha, were frequently selected and could be shown in vivo to confer >25-fold and >100-fold resistance, respectively, to amsacrine and approximately 3-fold cross-resistance to etoposide. Highly purified E571K and R486K human topoisomerase IIalpha proteins required 100-fold higher levels of amsacrine to induce DNA cleavage similar to that of wild-type protein, consistent with a resistance mechanism involving reduced cleavable complex formation. Our functional studies of the R486K mutation, previously identified in two amsacrine-resistant human cell lines and in human biopsy material, establish unequivocally that it confers resistance, and suggest mechanisms for its phenotypic expression in vivo. These results differ significantly from previous work using yeast topoisomerase II as a model system: introduction of the equivalent mutation to R486K (R476K) into the yeast enzyme did not give amsacrine resistance. We conclude that species-specific differences in topoisomerase II enzymes can affect the drug resistance phenotype of particular mutations and highlight the need to study the relevant human homolog.

Noninvasive estimation of the maximal lactate steady state in trained cyclists

PURPOSE

The purposes of this study were to estimate noninvasively the maximal lactate steady state (MLSS) in trained cyclists on a windload simulator with a velocity based technique and to determine whether the HR at MLSS (HR(MLSS)) elicited a similar blood lactate concentration (BLC) during field testing.

METHODS

To determine and verify MLSS, 10 male cyclists performed five to seven laboratory trials on separate days, including a VO2max test; a 5-km time trial (TT); and two or more 30-min trials at specific percentages of each subject's average 5-km TT speed (AVS5km). Mean+/-SD for the following variables were obtained at MLSS: velocity was 90.3+/-2.7% of the AVS5km, BLC was 5.4+/-1.6 mM, RPE was 15+/-2.1, VO2 was 80+/-6.3% of VO2max, and HR was 167+/-9.5 beats x min(-1), which was 88+/-3.8% of the mean maximum HR. Field tests included three laps of an 8-km road circuit at HR(MLSS) +/-3 beats x min(-1) and one lap at maximum sustainable velocity (a road TT).

RESULTS

There were no significant differences in BLC, HR, and RPE between the three steady-state road laps and the lab MLSS trial. There was also good agreement between the road and lab MLSS velocity/TT velocity ratios.

CONCLUSIONS

Our data suggest that 5-km TT cycling velocity, as measured on a windload simulator, may be used to estimate MLSS and the HR at MLSS for training purposes.

Impact of rapid weight loss on cognitive function in collegiate wrestlers

PURPOSE

The purpose of this study was to examine the effects of rapid weight loss (RWL) on cognitive function in collegiate wrestlers.

METHODS

Wrestlers (N = 14) and controls (N = 15) were college-aged males who were tested at three different times: baseline, RWL, and rehydration. Wrestlers practiced RWL in preparation for competition while controls maintained normal body weight and dietary practices throughout the study. At each test session, blood glucose, hemoglobin (Hgb), hematocrit (Hct), plasma volume (PV), and body weight were measured. Subjects also completed mood and hypoglycemic profiles as well as five short cognitive tests.

RESULTS

Two-way ANOVA and post-hoc tests revealed poorer performance for wrestlers than controls in two recall tests as well as greater mood negativity for the wrestlers after RWL. With RWL, between group differences were also evident in hypoglycemic profile, blood glucose, PV, and body weight. All measures returned to near baseline values after rehydration, suggesting that all physiological and cognitive effects associated with RWL were reversible. It is possible that precompetition anxiety may partially explain the results.

CONCLUSIONS

RWL in collegiate wrestlers before a competition appears to cause physiological effects that are accompanied by transient mood reduction and impairment of short-term memory. The potential negative impact of this practice on the student-athlete should be considered.

Identification of yeast DNA topoisomerase II mutants resistant to the antitumor drug doxorubicin: implications for the mechanisms of doxorubicin action and cytotoxicity

Doxorubicin is a therapeutically useful anticancer drug that exerts multiple biological effects. Its antitumor and cardiotoxic properties have been ascribed to anthracycline-mediated free radical damage to DNA and membranes. Evidence for this idea comes in part from the selection by doxorubicin from stationary phase yeast cells of mutants (petites) deficient in mitochondrial respiration and therefore defective in free radical generation. However, doxorubicin also binds to DNA topoisomerase II, converting the enzyme into a DNA damaging agent through the trapping of a covalent enzyme-DNA complex termed the 'cleavable complex.' We have used yeast to determine whether stabilization of cleavable complexes plays a role in doxorubicin action and cytotoxicity. A plasmid-borne yeast TOP2 gene was mutagenized with hydroxylamine and used to transform drug-permeable yeast strain JN394t2-4, which carries a temperature-sensitive top2-4 mutation in its chromosomal TOP2 gene. Selection in growth medium at the nonpermissive temperature of 35 degrees in the presence of doxorubicin resulted in the isolation of plasmid-borne top2 mutants specifying functional doxorubicin-resistant DNA topoisomerase II. Single-point changes of Gly748 to Glu or Ala642 to Ser in yeast topoisomerase II, which lie in and adjacent to the CAP-like DNA binding domain, respectively, were identified as responsible for resistance to doxorubicin, implicating these regions in drug action. None of the mutants selected in JN394t2-4, which has a rad52 defect in double-strand DNA break repair, was respiration-deficient. We conclude that topoisomerase II is an intracellular target for doxorubicin and that the genetic background and/or cell proliferation status can determine the relative importance of topoisomerase II- versus free radical-killing.

Water running with and without a flotation vest in competitive and recreational runners

The purpose of this study was to determine whether competitive and recreational runners would replicate land training intensity during water immersion (WI) running with (V) and without (NV) a flotation vest and during treadmill running (Tm). Seven female competitive runners (CR) and seven female noncompetitive runners (NR) were asked to replicate preferred land training intensity characteristic of a 45-min run under three conditions (Tm, V, and NV). When 20-min submaximal runs at the preferred land training intensity were performed for Tm, V, and NV conditions, CR were able to elicit a similar submaximal VO2 for all three conditions. In contrast, the NR group had a significantly (P < 0.05) lower VO2 (27%), HR (23%), VE (26%) and %VO2max (27%) during V versus Tm condition. During the NV condition, NR had a significantly lower VO2 (13%), %VO2max (13%), and a higher RPE compared with Tm running, and a significantly higher VO2 (16%), HR (15%), VE (24%), %VO2max (15%) and RPE compared with the V condition. Competitive runners were able to achieve training intensities similar to land training for WI running with or without a flotation vest. However, recreational runners failed to replicate land training pace, where intensity was significantly lower during WI running without a vest and lowest with a vest, despite efforts to maintain a similar level of exertion.

Molecular cloning and expression of the Candida albicans TOP2 gene allows study of fungal DNA topoisomerase II inhibitors in yeast

Candida albicans topoisomerase II, encoded by the TOP2 gene, mediates chromosome segregation by a double-strand DNA break mechanism and is a potential target for anti-fungal therapy. In this paper, we report the characterization of the C. albicans TOP2 gene and its use to develop a yeast system that allows the identification and study of anti-fungal topoisomerase II inhibitors in vivo. The gene, specifying a 1461-residue polypeptide with only 40% identity with human topoisomerase IIalpha and beta isoforms, was isolated from C. albicans on a 6.3 kb EcoRI fragment that mapped to chromosome 4. It was used to construct a plasmid in which TOP2 expresses a recombinant enzyme (residues 57-1461 of C. albicans topoisomerase II fused to the first five residues of Saccharomyces cerevisiae topoisomerase II) under the control of a galactose-inducible promoter. The plasmid rescued the lethal phenotype of a temperature-sensitive S. cerevisiae DNA topoisomerase II mutant allowing growth at 35 degrees C. Yeast cells, bearing ISE2 permeability and rad52 double-strand-break-repair mutations the growth of which at 35 degrees C was dependent on C. albicans topoisomerase II, were killed by the known topoisomerase II inhibitors amsacrine and doxorubicin. Parallel experiments in yeast expressing human topoisomerase IIalpha allowed the relative sensitivities of the fungal and host topoisomerases to be examined in the same genetic background. To compare the killing in vivo with drug inhibition in vitro, the recombinant C. albicans topoisomerase II protein was expressed and purified to near-homogeneity from S. cerevisiae yielding a 160 kDa polypeptide that displayed the expected ATP-dependent DNA-relaxation and DNA-decatenation activities. The enzyme, whether examined in vitro or complementing in S. cerevisiae, was comparably sensitive to amsacrine and doxorubicin. Our results suggest that potential topoisomerase II-targeting anti-fungal inhibitors can be identified and studied in S. cerevisiae.

Modification in movement accuracy in the triphasic pattern during a rapid forearm-flexion task

The present study was designed to investigate modifications in the triphasic EMG pattern during a forearm-flexion task at maximum speed which required three levels of movement accuracy. 36 subjects participated in 4 training sessions, performing a total of 200 repetitions of each movement. The fastest movement time was associated with the least accurate movement task. Likewise, the slowest movement time was found for the movement requiring the greatest accuracy. Differences in the duration and amplitude of agonist 1 activity, the start of agonist 2 activity, and the start and amplitude of antagonist activity were observed for the three movements. The results indicate that agonist 1 provides a propulsive force to initiate limb movement. The antagonist EMG activity was thought responsible for braking and correcting limb movement. Modifications in agonist 2 activity suggest this burst is related to movement velocity.