A Conceptual Framework and Treatment Taxonomy for Respiratory Lung Volume Training (RLVT).

OBJECTIVES: The purpose of this study was to describe the theoretical and procedural framework of a novel intervention, Respiratory Lung Volume Training (RLVT), and to implement a standardized treatment taxonomy to operationalize the RLVT treatment paradigm. STUDY DESIGN: This study involved a prospective design with a consensus treatment classification process. METHODS: The RLVT paradigm was developed based on biomechanical constructs governing the interactions of the respiratory and phonatory systems in voice production and principles of motor learning theory. In RLVT, higher levels of lung volume (LV) during speech are trained using multiple speech breathing strategies while providing real-time visual biofeedback with superimposed guidelines for desired LV initiation and termination levels. For people with primary muscle tension dysphonia (MTD), RLVT can capitalize on nonmuscular respiratory forces to increase efficiency of voice production with reduced speaking effort. To define and operationalize the treatment components of RLVT, six investigators with training in RLVT used the Rehabilitation Treatment Specification System to delineate the treatment targets, mechanisms of action, ingredients and dosing through a multistage, consensus decision-making process. RESULTS: The finalized taxonomy for RLVT included four treatment targets, with three addressing the area of Respiratory Function and one addressing Somatosensory Function. For each treatment target, three categories of ingredients were defined: (1) provide opportunities to practice breathing during voicing/speech, (2) provide feedback, and (3) provide volition ingredients. Within each ingredient category, three to seven specific ingredients were ultimately defined to further operationalize RLVT. CONCLUSIONS: The RLVT paradigm is a theoretically driven approach for optimizing speech breathing patterns to increase efficient voice production in people with primary MTD. By applying a standardized, systematic treatment taxonomy system to specify the components of RLVT, future researchers and clinicians can implement RLVT with improved fidelity and consistency to optimize treatment outcomes.

Isolated and Combined Respiratory Training for Muscle Tension Dysphonia: Preliminary Findings.

PURPOSE: The purpose of this study was to determine the feasibility of altering speech breathing patterns and dysphonia severity through training increased levels of lung volume use during speech. It was hypothesized that respiratory-based training would increase lung volume levels during speech as well as improve acoustic voice measures, and that the addition of laryngeal-based treatment would further improve voice acoustics by treatment completion. METHOD: A multiple baseline, single subject design was replicated over six participants with primary muscle tension dysphonia as a preliminary investigation of novel respiratory treatment methods. Following four baseline probes (1-4), two phases of treatment were implemented over 6 weeks. Respiratory lung volume-based training (RLVT) and subsequent performance was probed at sessions 5 to 7 and laryngeal-based training was added to the RLVT and probed at sessions 8 to 10. Visual biofeedback was used during RLVT to assist the motor learning process. Respiratory outcome measures of lung volume initiation, termination and excursion were objectively measured using respiratory plethysmography (InductoTrace), and cepstral and spectral-based acoustic measures were also determined at each time point. RESULTS: All participants showed improvement in one or more respiratory measures as well as reduced acoustic dysphonia severity following phase 1 of RLVT alone. Two participants achieved further marked improvement in acoustic voice measures after laryngeal-based training was added in phase 2 of treatment, but this was generally also accompanied by further improvement or stabilization of respiratory measures. CONCLUSION: Results from this preliminary study support the feasibility of RLVT for improving speech breathing behavior, and suggest that RLVT alone can improve objectively measured dysphonia severity.

Barth syndrome with severe dilated cardiomyopathy and growth hormone resistance: a case report.

OBJECTIVES: To describe the metabolic and endocrine features of a patient with Barth syndrome who showed evidence of growth hormone resistance. CASE PRESENTATION: A male proband deteriorated rapidly with lactic acidosis after a circumcision at age three weeks and was found to have severe dilated cardiomyopathy. A cardiomyopathy gene panel led to the diagnosis of TAZ-deficiency Barth syndrome. He subsequently experienced hypotonia and gross motor delay, feeding difficulties for the first four years, constitutional growth delay and one episode of ketotic hypoglycaemia. Cardiomyopathy resolved on oral anti-failure therapy by age three years. He had a hormonal pattern of growth hormone resistance, and growth hormone treatment was considered, however height velocity improved spontaneously after age 3½ years. He also had biochemical primary hypothyroidism. CONCLUSIONS: With careful metabolic management with l-arginine supplementation, overnight corn starch, and a prescribed exercise program, our patient's strength, endurance, level of physical activity and body composition improved significantly by age six years.

Clinical Features of Essential Voice Tremor and Associations with Tremor Severity and Response to Octanoic Acid Treatment.

OBJECTIVES/HYPOTHESIS: The purpose of this study was to characterize the clinical features, tremor variability, and factors related to octanoic acid (OA) treatment response in essential voice tremor (EVT). STUDY DESIGN: Prospective, double blind, placebo-controlled, crossover study with secondary analysis. METHODS: Clinical tremor features in 16 individuals with EVT were comprehensively assessed, and correlations with acoustic tremor severity were determined. Intrasubject and intersubject variability measures were analyzed from 18 repeated measures for each acoustic tremor variable. Clinical correlates of treatment response were evaluated, and cumulative effects over a 2-week period of OA drug dosing were assessed. RESULTS: Participants with EVT were 90% female with a mean age of 70.31 (±8.68) years at the time of testing. Neurologist-rated body tremor beyond the vocal tract region was present in 69% of participants, and multiple vocal tract regions contributed to the voice tremor. The mean frequency of amplitude tremor was 4.67 Hz (±0.88). Respiratory tremor was evident in 50% of participants. Participants experienced moderate voice-related disability as assessed on the Voice Handicap Index-10 (19.38, ±8.50), and increased speaking effort. Acoustic tremor severity was significantly associated with severity of tremor affecting vocal tract structures. Overall intrasubject consistency was strong (single measures intraclass correlation coefficient = 0.701, P < .01), with high intersubject variability. Acoustic tremor severity was significantly, positively associated with treatment response, and results suggested a cumulative OA benefit for magnitude of amplitude tremor. CONCLUSIONS: This study identified common clinical correlates of EVT and demonstrated positive associations between acoustic tremor severity, severity of affected vocal tract structures, and response to treatment. LEVEL OF EVIDENCE: 2 Laryngoscope, 131:E2792-E2801, 2021.

A Pilot Study of Bioenergetic Marker Relationships in Gulf War Illness: Phosphocreatine Recovery vs. Citric Acid Cycle Intermediates.

Impaired bioenergetics have been reported in veterans with Gulf War illness (VGWIs), including prolonged post-exercise recovery of phosphocreatine (PCr-R) assessed with 31Phosphorus magnetic resonance spectroscopy. The citric acid cycle (CAC) is considered the most important metabolic pathway for supplying energy, with relationships among CAC markers reported to shift in some but not all impaired bioenergetic settings. We sought to assess relations of CAC markers to one another and to PCr-R. Participants were 33 VGWIs and 33 healthy controls 1:1 matched on age-sex-ethnicity. We assessed seven CAC intermediates, and evaluated PCr-R in a subset of matched case-control pairs (N = 14). CAC markers did not significantly differ between cases and controls. Relationships of alpha-ketoglutarate to malate, isocitrate, and succinate were strongly significant in cases with materially weaker relationships in controls, suggesting possible shifts in these markers in concert in VGWIs. PCr-R correlated strongly with five of seven CAC markers in controls (succinate, malate, fumarate, citrate, isocitrate, range r = -0.74 to -0.88), but bore no relationship in VGWIs. In summary, PCr-R related significantly to CAC markers in healthy controls, but not VGWIs. In contrast, relations of CAC markers to one another appeared to shift (often strengthen) in VGWIs.

Assessment of Tongue Position and Laryngeal Height in Two Professional Voice Populations.

Purpose To advance our current knowledge of singer physiology by using ultrasonography in combination with acoustic measures to compare physiological differences between musical theater (MT) and opera (OP) singers under controlled phonation conditions. Primary objectives addressed in this study were (a) to determine if differences in hyolaryngeal and vocal fold contact dynamics occur between two professional voice populations (MT and OP) during singing tasks and (b) to determine if differences occur between MT and OP singers in oral configuration and associated acoustic resonance during singing tasks. Method Twenty-one singers (10 MT and 11 OP) were included. All participants were currently enrolled in a music program. Experimental procedures consisted of sustained phonation on the vowels /i/ and /ɑ/ during both a low-pitch task and a high-pitch task. Measures of hyolaryngeal elevation, tongue height, and tongue advancement were assessed using ultrasonography. Vocal fold contact dynamics were measured using electroglottography. Simultaneous acoustic recordings were obtained during all ultrasonography procedures for analysis of the first two formant frequencies. Results Significant oral configuration differences, reflected by measures of tongue height and tongue advancement, were seen between groups. Measures of acoustic resonance also showed significant differences between groups during specific tasks. Both singer groups significantly raised their hyoid position when singing high-pitched vowels, but hyoid elevation was not statistically different between groups. Likewise, vocal fold contact dynamics did not significantly differentiate the two singer groups. Conclusions These findings suggest that, under controlled phonation conditions, MT singers alter their oral configuration and achieve differing resultant formants as compared with OP singers. Because singers are at a high risk of developing a voice disorder, understanding how these two groups of singers adjust their vocal tract configuration during their specific singing genre may help to identify risky vocal behavior and provide a basis for prevention of voice disorders.

Post-overdose interventions triggered by calling 911: Centering the perspectives of people who use drugs (PWUDs).

BACKGROUND: Opioid overdose deaths have increased exponentially in the United States. Bystander response to opioid overdose ideally involves administering naloxone, providing rescue breathing, and calling 911 to summon emergency medical assistance. Recently in the US, public health and public safety agencies have begun seeking to use 911 calls as a method to identify and deliver post-overdose interventions to opioid overdose patients. Little is known about the opinions of PWUDs about the barriers, benefits, or potential harms of post-overdose interventions linked to the 911 system. We sought to understand the perspectives of PWUDs about a method for using 911 data to identify opioid overdose cases and trigger a post-overdose intervention. METHODS AND FINDINGS: We conducted three focus groups with 11 PWUDs in 2018. Results are organized into 4 categories: willingness to call 911 (benefits and risks of calling), thoughts about a technique to identify opioid overdoses in 911 data (benefits and concerns), thoughts about the proposed post-overdose intervention (benefits and concerns), and recommendations for developing an ideal post-overdose intervention. For most participants, calling 911 was synonymous with "calling the police" and law enforcement-related fears were pervasive, limiting willingness to engage with the 911 system. The technique to identify opioid overdoses and the proposed post-overdose intervention were identified as potentially lifesaving, but the benefits were balanced by concerns related to law enforcement involvement, intervention timing, and risks to privacy/reputation. Nearly universally, participants wished for a way to summon emergency medical assistance without triggering a law enforcement response. CONCLUSIONS: The fact that the 911 system in the US inextricably links emergency medical assistance with law enforcement response inherently problematizes calling 911 for PWUDs, and has implications for surveillance and intervention. It is imperative to center the perspectives of PWUDs when designing and implementing interventions that rely on the 911 system for activation.

The Effect of Octanoic Acid on Essential Voice Tremor: A Double-Blind, Placebo-Controlled Study.

OBJECTIVES/HYPOTHESIS: The purpose of this study was to determine the effects of octanoic acid on acoustic, perceptual, and functional aspects of essential voice tremor (EVT). STUDY DESIGN: Prospective, double-blind, placebo-controlled, crossover study. METHODS: Sixteen participants with a diagnosis of EVT were randomized to a 3-week dosing condition of octanoic acid or placebo, followed by a 2-week washout period and crossover to the other condition for an additional 3 weeks. Baseline and post-testing sessions were completed before and at the completion of each condition. Primary outcome measures were the magnitude of amplitude and frequency tremor, measured from the acoustic signal. Secondary outcomes were auditory-perceptual ratings of tremor severity and self-ratings of voice handicap. RESULTS: Magnitude of amplitude and frequency tremor were significantly lower after 3 weeks of octanoic acid dosing as compared to the placebo condition. Auditory-perceptual ratings of tremor severity did not show significant differences between conditions. A trend toward better voice was seen for the sustained vowel ratings, but not the sentence-level ratings. No significant differences between conditions were seen on self-reported voice disability as assessed on the Voice Handicap Index-10. CONCLUSIONS: The results of this controlled investigation support the potential utility of octanoic acid for reducing the magnitude of tremor in people with EVT. Further research is needed to determine whether different dosing or treatment combinations can improve functional communication in EVT. LEVEL OF EVIDENCE: 1 Laryngoscope, 129:1882-1890, 2019.

Randomized open-label trial of dextromethorphan in Rett syndrome.

OBJECTIVE: To determine safety and perform a preliminary assessment of dose-dependent efficacy of dextromethorphan in normalizing electrographic spikes, clinical seizures, and behavioral and cognitive functions in girls with Rett syndrome. METHODS: We used a prospective randomized, open-label trial in fast metabolizers of dextromethorphan to examine the effect of dextromethorphan on core clinical features of Rett syndrome. Interictal spike activity and clinical seizures were determined using EEG and parent reporting. Cognitive data were obtained using the Mullen Scales of Early Learning and Vineland Adaptive Behavior Scales, while behavioral data were obtained from parent-completed checklists, the Aberrant Behavior Checklist-Community Version, and the Screen for Social Interaction. Anthropometric data were obtained according to the National Health and Nutrition Examination Survey. The Rett Syndrome Severity Scale provided a clinical global impression of the effect of dextromethorphan on clinical severity. RESULTS: Dextromethorphan is safe for use in 3- to 15-year-old girls with Rett syndrome. Thirty-five girls were treated with 1 of 3 doses of dextromethorphan over a period of 6 months. Statistically significant dose-dependent improvements were seen in clinical seizures, receptive language, and behavioral hyperactivity. There was no significant improvement in global clinical severity as measured by the Rett Syndrome Severity Scale. CONCLUSIONS: Dextromethorphan is a potent noncompetitive antagonist of the NMDA receptor channel that is safe for use in young girls with Rett syndrome. Preliminary evidence suggests that dextromethorphan may improve some core features of Rett syndrome. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that dextromethorphan at various doses does not change EEG spike counts over 6 months, though precision was limited to exclude an important effect.

Replication stress affects the fidelity of nucleosome-mediated epigenetic inheritance.

The fidelity of epigenetic inheritance or, the precision by which epigenetic information is passed along, is an essential parameter for measuring the effectiveness of the process. How the precision of the process is achieved or modulated, however, remains largely elusive. We have performed quantitative measurement of epigenetic fidelity, using position effect variegation (PEV) in Schizosaccharomyces pombe as readout, to explore whether replication perturbation affects nucleosome-mediated epigenetic inheritance. We show that replication stresses, due to either hydroxyurea treatment or various forms of genetic lesions of the replication machinery, reduce the inheritance accuracy of CENP-A/Cnp1 nucleosome positioning within centromere. Mechanistically, we demonstrate that excessive formation of single-stranded DNA, a common molecular abnormality under these conditions, might have correlation with the reduction in fidelity of centromeric chromatin duplication. Furthermore, we show that replication stress broadly changes chromatin structure at various loci in the genome, such as telomere heterochromatin expanding and mating type locus heterochromatin spreading out of the boundaries. Interestingly, the levels of inheritable expanding at sub-telomeric heterochromatin regions are highly variable among independent cell populations. Finally, we show that HU treatment of the multi-cellular organisms C. elegans and D. melanogaster affects epigenetically programmed development and PEV, illustrating the evolutionary conservation of the phenomenon. Replication stress, in addition to its demonstrated role in genetic instability, promotes variable epigenetic instability throughout the epigenome.

A placebo-controlled trial of simvastatin therapy in Smith-Lemli-Opitz syndrome.

BACKGROUND: Smith-Lemli-Opitz syndrome (SLOS) is a multiple malformation/cognitive impairment syndrome characterized by the accumulation of 7-dehydrocholesterol, a precursor sterol of cholesterol. Simvastatin, a 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor that crosses the blood-brain barrier, has been proposed for the treatment of SLOS based on in vitro and in vivo studies suggesting that simvastatin increases the expression of hypomorphic DHCR7 alleles. METHODS: Safety and efficacy of simvastatin therapy in 23 patients with mild to typical SLOS were evaluated in a randomized, double-blind, placebo-controlled trial. The crossover trial consisted of two 12-month treatment phases separated by a 2-month washout period. RESULTS: No safety issues were identified in this study. Plasma dehydrocholesterol concentrations decreased significantly: 8.9 ± 8.4% on placebo to 6.1 ± 5.5% on simvastatin (P < 0.005); we observed a trend toward decreased cerebrospinal fluid dehydrocholesterol concentrations. A significant improvement (P = 0.017, paired t-test) was observed on the irritability subscale of the Aberrant Behavior Checklist-C when subjects were taking simvastatin. CONCLUSION: This article reports what is, to our knowledge, the first randomized, placebo-controlled trial designed to test the safety and efficacy of simvastatin therapy in SLOS. Simvastatin seems to be relatively safe in patients with SLOS, improves the serum dehydrocholesterol-to-total sterol ratio, and significantly improves irritability symptoms in patients with mild to classic SLOS.Genet Med 19 3, 297-305.

The effect of anchors on reliability of endoscopic tremor ratings.

OBJECTIVES/HYPOTHESIS: The purpose of this study was to determine the effects of anchors and training on intrarater and inter-rater reliability for visual-perceptual, endoscopic tremor ratings. STUDY DESIGN: Prospective cohort study. METHODS: Nasoendoscopy recordings of 10 participants with a diagnosis of essential voice tremor were evaluated by five voice specialists using the Vocal Tremor Scoring System. Ratings were performed before, immediately after, and 4 weeks after implementation of a training program with anchor stimuli. Immediate and long-term post-training ratings were performed with simultaneous use of anchor samples for each rating. RESULTS: Intrarater reliability showed significant improvement from pretraining to immediate and long-term post-training. Mean correlation coefficients (Spearman's rho) increased from 0.71 at pretraining to 0.84 and 0.90 at immediate and long-term post-training, respectively. Inter-rater reliability was not affected by training with anchors, with mean correlation coefficients ranging from 0.62 at pretraining to 0.58 and 0.64 at immediate and long-term post-training, respectively. CONCLUSIONS: Consistent, reproducible ratings are critical for the interpretation and comparison of endoscopic tremor data. Reliability findings from this study indicate that the use of anchor samples as referents for making ordinal judgments about the severity of tremor in oropharyngeal and laryngeal regions was helpful for improving internal standards and consistency but less useful for calibrating across different raters. LEVEL OF EVIDENCE: 4 Laryngoscope, 2016 127:411-416, 2017.

Altered cholesterol biosynthesis causes precocious neurogenesis in the developing mouse forebrain.

We previously reported a mutation in the cholesterol biosynthesis gene, hydroxysteroid (17-beta) dehydrogenase 7 (Hsd17b7(rudolph)), that results in striking embryonic forebrain dysgenesis. Here we describe abnormal patterns of neuroprogenitor proliferation in the mutant forebrain, namely, a decrease in mitotic cells within the ventricular zone (VZ) and an increase through the remainder of the cortex by E11.5. Further evidence suggests mutant cells undergo abnormal interkinetic nuclear migration (IKNM). Furthermore, intermediate progenitors are increased at the expense of apical progenitors by E12.5, and post-mitotic neurons are expanded by E14.5. In vitro primary neuron culture further supports our model of accelerated cortical differentiation in the mutant. Combined administration of a statin and dietary cholesterol in utero achieved partial reversal of multiple developmental abnormalities in the Hsd17b7(rudolph) embryo, including the forebrain. These results suggest that abnormally increased levels of specific cholesterol precursors in the Hsd17b7(rudolph) embryo cause cortical dysgenesis by altering patterns of neurogenesis.

A specific mutation in TBL1XR1 causes Pierpont syndrome.

BACKGROUND: The combination of developmental delay, facial characteristics, hearing loss and abnormal fat distribution in the distal limbs is known as Pierpont syndrome. The aim of the present study was to detect and study the cause of Pierpont syndrome. METHODS: We used whole-exome sequencing to analyse four unrelated individuals with Pierpont syndrome, and Sanger sequencing in two other unrelated affected individuals. Expression of mRNA of the wild-type candidate gene was analysed in human postmortem brain specimens, adipose tissue, muscle and liver. Expression of RNA in lymphocytes in patients and controls was additionally analysed. The variant protein was expressed in, and purified from, HEK293 cells to assess its effect on protein folding and function. RESULTS: We identified a single heterozygous missense variant, c.1337A>G (p.Tyr446Cys), in transducin ß-like 1 X-linked receptor 1 (TBL1XR1) as disease-causing in all patients. TBL1XR1 mRNA expression was demonstrated in pituitary, hypothalamus, white and brown adipose tissue, muscle and liver. mRNA expression is lower in lymphocytes of two patients compared with the four controls. The mutant TBL1XR1 protein assembled correctly into the nuclear receptor corepressor (NCoR)/ silencing mediator for retinoid and thyroid receptors (SMRT) complex, suggesting a dominant-negative mechanism. This contrasts with loss-of-function germline TBL1XR1 deletions and other TBL1XR1 mutations that have been implicated in autism. However, autism is not present in individuals with Pierpont syndrome. CONCLUSIONS: This study identifies a specific TBL1XR1 mutation as the cause of Pierpont syndrome. Deletions and other mutations in TBL1XR1 can cause autism. The marked differences between Pierpont patients with the p.Tyr446Cys mutation and individuals with other mutations and whole gene deletions indicate a specific, but as yet unknown, disease mechanism of the TBL1XR1 p.Tyr446Cys mutation.

A Preliminary Quantitative Comparison of Vibratory Amplitude Using Rigid and Flexible Stroboscopic Assessment.

STUDY OBJECTIVE: The purpose of this study was to establish preliminary, quantitative data on amplitude of vibration during stroboscopic assessment in healthy speakers with normal voice characteristics. Amplitude of vocal fold vibration is a core physiological parameter used in diagnosing voice disorders, yet quantitative data are lacking to guide the determination of what constitutes normal vibratory amplitude. METHODS/STUDY DESIGN: Eleven participants were assessed during sustained vowel production using rigid and flexible endoscopy with stroboscopy. Still images were extracted from digital recordings of a sustained /i/ produced at a comfortable pitch and loudness, with F0 controlled so that levels were within ±15% of each participant's comfortable mean level as determined from connected speech. Glottal width (GW), true vocal fold (TVF) length, and TVF width were measured from still frames representing the maximum open phase of the vibratory cycle. To control for anatomic and magnification differences across participants, GW was normalized to TVF length. GW as a ratio of TVF width was also computed for comparison with prior studies. RESULTS: Mean values and standard deviations were computed for the normalized measures. Paired t tests showed no significant differences between rigid and flexible endoscopy methods. Interrater and intrarater reliability values for raw measurements were found to be high (0.89-0.99). CONCLUSIONS: These preliminary quantitative data may be helpful in determining normality or abnormality of vocal fold vibration. Results indicate that quantified amplitude of vibration is similar between endoscopic methods, a clinically relevant finding for individuals performing and interpreting stroboscopic assessments.

Operating Modes and Cooling Capabilities of the 3-Stage ADR Developed for the Soft-X-ray Spectrometer Instrument on Astro-H.

A 3-stage adiabatic demagnetization refrigerator (ADR)[1] is used on the Soft X-ray Spectrometer instrument[2] on Astro-H[3] to cool a 6×6 array of x-ray microcalorimeters to 50 mK. The ADR is supported by a cryogenic system[4] consisting of a superfluid helium tank, a 4.5 K Joule-Thomson (JT) cryocooler, and additional 2-stage Stirling cryocoolers that pre-cool the JT cooler and cool radiation shields within the cryostat. The ADR is configured so that it can use either the liquid helium or the JT cryocooler as its heat sink, giving the instrument an unusual degree of tolerance for component failures or degradation in the cryogenic system. The flight detector assembly, ADR and dewar were integrated into the flight dewar in early 2014, and have since been extensively characterized and calibrated. This paper summarizes the operation and performance of the ADR in all of its operating modes.

Modeling the mitochondrial cardiomyopathy of Barth syndrome with induced pluripotent stem cell and heart-on-chip technologies.

Study of monogenic mitochondrial cardiomyopathies may yield insights into mitochondrial roles in cardiac development and disease. Here, we combined patient-derived and genetically engineered induced pluripotent stem cells (iPSCs) with tissue engineering to elucidate the pathophysiology underlying the cardiomyopathy of Barth syndrome (BTHS), a mitochondrial disorder caused by mutation of the gene encoding tafazzin (TAZ). Using BTHS iPSC-derived cardiomyocytes (iPSC-CMs), we defined metabolic, structural and functional abnormalities associated with TAZ mutation. BTHS iPSC-CMs assembled sparse and irregular sarcomeres, and engineered BTHS 'heart-on-chip' tissues contracted weakly. Gene replacement and genome editing demonstrated that TAZ mutation is necessary and sufficient for these phenotypes. Sarcomere assembly and myocardial contraction abnormalities occurred in the context of normal whole-cell ATP levels. Excess levels of reactive oxygen species mechanistically linked TAZ mutation to impaired cardiomyocyte function. Our study provides new insights into the pathogenesis of Barth syndrome, suggests new treatment strategies and advances iPSC-based in vitro modeling of cardiomyopathy.

Clinical laboratory studies in Barth Syndrome.

Barth Syndrome is a rare X-linked disorder characterized principally by dilated cardiomyopathy, skeletal myopathy and neutropenia and caused by defects in tafazzin, an enzyme responsible for modifying the acyl chain moieties of cardiolipin. While several comprehensive clinical studies of Barth Syndrome have been published detailing cardiac and hematologic features, descriptions of its biochemical characteristics are limited. To gain a better understanding of the clinical biochemistry of this rare disease, we measured hematologic and biochemical values in a cohort of Barth Syndrome patients. We characterized multiple biochemical parameters, including plasma amino acids, plasma 3-methylglutaconic acid, cholesterol, cholesterol synthetic intermediates, and red blood cell membrane fatty acid profiles in 28 individuals with Barth Syndrome from ages 10 months to 30 years. We describe a unique biochemical profile for these patients, including decreased plasma arginine levels. We further studied the plasma amino acid profiles, cholesterol, cholesterol synthetic intermediates, and plasma 3-methylglutaconic acid levels in 8 female carriers and showed that they do not share any of the distinct, Barth Syndrome-specific biochemical laboratory abnormalities. Our studies augment and expand the biochemical profiles of individuals with Barth Syndrome, describe a unique biochemical profile for these patients, and provide insight into the possible underlying biochemical pathology in this disorder.

Generation of a useful roX1 allele by targeted gene conversion.

Methods for altering the sequence of endogenous Drosophila melanogaster genes remain labor-intensive. We have tested a relatively simple strategy that enables the introduction of engineered mutations in the vicinity of existing P-elements. This method was used to generate useful alleles of the roX1 gene, which produces a noncoding RNA involved in dosage compensation. The desired change was first introduced into a genomic clone of roX1 and transgenic flies were generated that carry this sequence in a P-element. Targeted transposition was then used to move the P-element into roX1. Remobilization of the targeted insertion produced large numbers of offspring carrying chromosomes that had precisely introduced the engineered sequences into roX1. We postulate that this occurred by gap repair, using the P-element on the sister chromatid as template. This strategy was used to introduce six MS2 loops into the roX1 gene (roX1(MS2-6)), enabling detection of roX1 RNA by a MCP-GFP fusion protein in embryos. The roX1(MS2-6) remains under the control of the authentic promoter and within the correct genomic context, features expected to contribute to normal roX1 function. The ability to replace relatively large blocks of sequence suggests that this method will be of general use.

A food effect study and dose proportionality study to assess the pharmacokinetics and safety of bardoxolone methyl in healthy volunteers.

This study investigated the effect of food on the plasma pharmacokinetics of bardoxolone methyl, an antioxidant inflammation modulator, at a 20 mg dose, and the dose proportionality of bardoxolone methyl pharmacokinetics from 20 to 80 mg. It was a single-dose study conducted at a single center in 32 healthy volunteers aged 18-45 years using an amorphous spray-dried dispersion formulation of bardoxolone methyl. In Part A, 16 subjects received single 20 mg doses of bardoxolone methyl under fasting and non-fasting conditions. In Part B, 16 subjects received a single 60 or 80 mg dose of bardoxolone methyl and a matching placebo dose under fasting conditions. Blood samples for pharmacokinetic analysis were taken over 120 hours following dose administration. Single dose administration of 20, 60, and 80 mg bardoxolone methyl was safe and well-tolerated in healthy volunteers. Total bardoxolone methyl exposure was unchanged in the presence of food. However, doses of bardoxolone methyl above 20 mg appear to have a saturated dissolution or absorption process and are associated with less than proportional increases in drug exposure.