Transcriptome profile of subsynaptic myonuclei at the neuromuscular junction in embryogenesis

Skeletal muscle fiber is a large syncytium with multiple and evenly distributed nuclei. Adult subsynaptic myonuclei beneath the neuromuscular junction (NMJ) express specific genes, the products of which coordinately function in the maintenance of the pre- and post-synaptic regions. However, the gene expression profiles that promote the NMJ formation during embryogenesis remain largely unexplored. We performed single-nucleus RNA sequencing (snRNA-seq) analysis of embryonic and neonatal mouse diaphragms, and found that each myonucleus had a distinct transcriptome pattern during the NMJ formation. Among the previously reported NMJ-constituting genes, Dok7, Chrna1, and Chrnd are specifically expressed in subsynaptic myonuclei at E18.5. In the E18.5 diaphragm, ca. 10.7% of the myonuclei express genes for the NMJ formation (Dok7, Chrna1, and Chrnd) together with four representative β-catenin regulators (Amotl2, Ptprk, Fam53b, and Tcf7l2). Additionally, the temporal gene expression patterns of these seven genes are synchronized in differentiating C2C12 myoblasts. Amotl2 and Ptprk are expressed in the sarcoplasm, where β-catenin serves as a structural protein to organize the membrane-anchored NMJ structure. In contrast, Fam53b and Tcf7l2 are expressed in the myonucleus, where β-catenin serves as a transcriptional coactivator in Wnt/β-catenin signaling at the NMJ. In C2C12 myotubes, knockdown of Amotl2 or Ptprk markedly, and that of Fam53b and Tcf7l2 less efficiently, impair the clustering of acetylcholine receptors. In contrast, knockdown of Fam53b and Tcf7l2, but not of Amotl2 or Ptprk, impairs the gene expression of Slit2 encoding an axonal attractant for motor neurons, which is required for the maturation of motor nerve terminal. Thus, Amotl2 and Ptprk exert different roles at the NM compared to Fam53b and Tcf7l2. Additionally, Wnt ligands originating from the spinal motor neurons and the perichondrium/chondrocyte are likely to work remotely on the subsynaptic nuclei and the myotendinous junctional nuclei, respectively. We conclude that snRNA-seq analysis of embryonic/neonatal diaphragms reveal a novel coordinated expression profile especially in the Wnt/β-catenin signaling that regulate the formation of the embryonic NMJ.

Development and validation of the Japanese version of the Bedtime Procrastination Scale (BPS-J)

BACKGROUND

The average sleep duration of Japanese people is shorter than that of people from other countries, and bedtime procrastination is suspected to be one of the factors contributing to this issue. This study aimed to develop and validate the Japanese version of the Bedtime Procrastination Scale (BPS-J).

METHODS

The BPS-J was developed through procedures including the translation and back-translation of the scale, cognitive interviews with 100 participants who reported having experiences of being diagnosed with insufficient sleep syndrome (ISS) or receiving treatment for ISS using open-ended online questionnaires, and expert checking. To investigate the scale's validity and reliability, an online survey was conducted with daytime workers aged 20 - 65 years without a history of sleep disorders other than ISS. Half the participants were retested using the same survey after 14 days. Participants' responses to the Brief Self-Control Scale (BSCS), General Procrastination Scale (GPS), and Munich ChronoType Questionnaire (MCTQ), and data on sleep-related variables such as sleep duration on workdays and the days per week of fatigue or sleep loss, sex, and age, were collected.

RESULTS

We analyzed data from 574 participants to assess scale validity. We then analyzed data from 280 participants to determine test-retest reliability. Confirmatory factor analyses revealed that the two-factor model without Item 2 was most suitable for the BPS-J, unlike other language versions. Regardless of the full-item model or the model with Item 2 eliminated, sufficient reliability and significant correlations with the BSCS, GPS, MCTQ, and sleep-related variables such as sleep duration per night on work days, days per week of feeling fatigued, and days per week of sleep loss were observed. Logistic and linear regressions showed that the relationships between the BPS-J, sleep-related variables, and MCTQ were maintained after adjusting for sex and age.

CONCLUSION

The BPS-J had sufficient validity and reliability. Further, eliminating Item 2 from the original version of the BPS strengthened the ability to survey Japanese daytime workers.

Emerin deficiency does not exacerbate cardiomyopathy in a murine model of Emery-Dreifuss muscular dystrophy caused by an LMNA gene mutation

Emery-Dreifuss muscular dystrophy (EDMD), caused by mutations in genes encoding nuclear envelope proteins, is clinically characterized by muscular dystrophy, early joint contracture, and life-threatening cardiac abnormalities. To elucidate the pathophysiological mechanisms underlying striated muscle involvement in EDMD, we previously established a murine model with mutations in Emd and Lmna (Emd-/-/LmnaH222P/H222P; EH), and reported exacerbated skeletal muscle phenotypes and no notable cardiac phenotypes at 12 weeks of age. We predicted that lack of emerin in LmnaH222P/H222P mice causes an earlier onset and more pronounced cardiac dysfunction at later stages. In this study, cardiac abnormalities of EDMD mice were compared at 18 and 30 weeks of age. Contrary to our expectations, physiological and histological analyses indicated that emerin deficiency causes no prominent differences of cardiac involvement in LmnaH222P/H222P mice. These results suggest that emerin does not contribute to cardiomyopathy progression in LmnaH222P/H222P mice.

Factors influencing the decision to introduce alternative nutrition in patients with Duchenne muscular dystrophy

INTRODUCTION/AIMS

Nutritional management of adults with Duchenne muscular dystrophy (DMD) is an important clinical issue. However, it is not clear which dysphagia-related factors should prompt introduction of alternative nutrition (AN). We aimed to determine which patients with DMD were introduced to AN.

METHODS

This retrospective study included 56 patients with DMD (median age, 23.5 years). They were divided into patients able to continue oral feeding (OF) and those introduced to AN. Body weight, frequency of ventilator use, daily meals, history of steroid treatment, results of videofluoroscopic examination of swallowing (VF), and awareness of dysphagia were evaluated.

RESULTS

Of 56 patients, 19 were in the AN group. After AN introduction, 93% of the patients continued oral intake. The proportion of patients who consumed chopped and liquid diets was higher, and body weight was lower, in the AN than in the OF group. There were no significant differences in age, upper limb function of feeding, frequency of ventilator use, or history of steroid therapy between the two groups. The frequencies of aspiration and residue in the pyriform sinus in VF were higher in the AN group than in the OF group. Decision-tree analysis showed that food form and subjective difficulty swallowing solid foods were the most important factors affecting the decision-making for AN.

DISCUSSION

Patients with DMD who had difficulty eating solid foods were started on AN because they were unable to maintain their weight. These findings provide information for future longitudinal studies to assess the value of AN.

Hydrogen sulfide and polysulfides induce GABA/glutamate/D-serine release, facilitate hippocampal LTP, and regulate behavioral hyperactivity

Hydrogen sulfide (H2S) and polysulfides (H2Sn, n ≥ 2) are signaling molecules produced by 3-mercaptopyruvate sulfurtransferase (3MST) that play various physiological roles, including the induction of hippocampal long-term potentiation (LTP), a synaptic model of memory formation, by enhancing N-methyl-D-aspartate (NMDA) receptor activity. However, the presynaptic action of H2S/H2Sn on neurotransmitter release, regulation of LTP induction, and animal behavior are poorly understood. Here, we showed that H2S/H2S2 applied to the rat hippocampus by in vivo microdialysis induces the release of GABA, glutamate, and D-serine, a co-agonist of NMDA receptors. Animals with genetically knocked-out 3MST and the target of H2S2, transient receptor potential ankyrin 1 (TRPA1) channels, revealed that H2S/H2S2, 3MST, and TRPA1 activation play a critical role in LTP induction, and the lack of 3MST causes behavioral hypersensitivity to NMDA receptor antagonism, as in schizophrenia. H2S/H2Sn, 3MST, and TRPA1 channels have therapeutic potential for psychiatric diseases and cognitive deficits.

Difference in the risk of discrimination on psychological distress experienced by early wave infected and late wave infected COVID-19 survivors in Japan

The psychological distress experienced by coronavirus disease of 2019 (COVID-19) survivors after recovery from the illness is amplified by discrimination endured because of their infection status. However, the difference in the risk of facing discrimination and risk of experiencing psychological distress in the early and late waves of the COVID-19 pandemic remain unclear. This study aimed to investigate whether the risk of facing discrimination because of infection status was lower in the early or late waves and whether risk of discrimination on psychological distress was more serious in later, rather than earlier waves. We conducted two online surveys to collect data from survivors divided into two groups. The participants with scores of five or more on the Kessler Psychological Distress Scale were identified as having experienced psychological distress. The participants were identified as having experienced discrimination based on infection status if they had endured being blamed, some type of discrimination, or having themselves or their families maligned. The timing of infection was split into infected during early waves of the pandemic for 2021 participants and infected during later waves of the pandemic for 2022 participants. Modified Poisson regression analyses were performed using experiences of discrimination as criteria and timing of infection as predictors. Modified Poisson regression analyses were further performed using the presence of psychological distress as a criteria and experiences of discrimination and timing of infection as the criteria, in addition to interaction effect of these es. The data of 6010 participants who were infected in early waves and 5344 participants who were infected in later waves were analyzed. The risks of being blamed, some forms of discrimination, and participants and their families being maligned were significantly lower in the group who were infected in later waves than those infected in earlier waves. Experiences of discrimination were highly associated with psychological distress in those infected in later waves than those infected in earlier waves, while only being blamed showed a significant association. Risk of discrimination was found to be lower in those infected in later waves, whereas risk of discrimination on psychological distress was shown to be more serious in those infected in later waves. Therefore, we submit that it is more important to support COVID-19 survivors who face discrimination, than it is to attempt to decrease the current discriminatory climate caused by the COVID-19 pandemic.

Nuclear Expression of TDP-43 Is Linked with Morphology and Ubiquitylation of Cytoplasmic Aggregates in Amyotrophic Lateral Sclerosis

The transactive response DNA-binding protein of 43 kDa (TDP-43) is a pathological protein of amyotrophic lateral sclerosis (ALS). TDP-43 pathology is characterized by a combination of the cytoplasmic aggregation and nuclear clearance of this protein. However, the mechanisms underlying TDP-43 pathology have not been fully clarified. The aim of this study was to evaluate the relationships between the expression level of nuclear TDP-43 and the pathological properties of cytoplasmic aggregates in autopsied ALS cases. We included 22 consecutively autopsied cases with sporadic TDP-43-related ALS. The motor neuron systems were neuropathologically assessed. We identified 790 neurons with cytoplasmic TDP-43 inclusions from the lower motor neuron system of included cases. Nuclear TDP-43 disappeared in 84% (n = 660) and expressed in 16% (n = 130) of neurons with cytoplasmic inclusions; the former was defined as TDP-43 cytoplasmic immunoreactivity (c-ir), and the latter was defined as nuclear and cytoplasmic immunoreactivity (n/c-ir). Morphologically, diffuse cytoplasmic inclusions were significantly more prevalent in TDP-43 n/c-ir neurons than in c-ir neurons, while skein-like and round inclusions were less prevalent in n/c-ir neurons. The cytoplasmic inclusions of TDP-43 n/c-ir neurons were phosphorylated but poorly ubiquitylated when compared with those of c-ir neurons. TDP-43 n/c-ir neurons became less dominant than the c-ir neurons among cases with a prolonged disease duration. The expression level of nuclear TDP-43 was significantly lower in n/c-ir neurons than in normal neurons without cytoplasmic inclusions. Our results indicate that the maturation of cytoplasmic TDP-43 inclusions correlates with the depletion of nuclear TDP-43 in each affected neuron. This finding supports the view that an imbalance between nuclear and cytoplasmic TDP-43 may be an essential pathway to TDP-43 pathology.

Posterior Spinal Fusion Surgery for Neuromuscular Disease Patients with Severe Scoliosis Whose Cobb Angle Was over 100 Degrees

Background and objectives: Patients with neuromuscular diseases usually have progressive neuromuscular scoliosis (NMS), requiring invasive surgery. Some patients present with severe scoliosis at the time of consultation and are difficult to treat. Posterior spinal fusion (PSF) surgery combined with anterior release and pre- or intraoperative traction would be effective for severe spinal deformities but would be invasive. This study aimed to evaluate the outcomes of PSF-only surgery for patients with severe NMS with a Cobb angle > 100°. Materials and Methods: Thirty NMS patients (13 boys and 17 girls; mean age 13.8 years) who underwent PSF-only surgery for scoliosis with a Cobb angle > 100° were included. We reviewed the lower instrumented vertebra (LIV), duration of surgery, blood loss, perioperative complications, preoperative clinical findings, and radiographic findings, including Cobb angle and pelvic obliquity (PO) in the sitting position pre- and postoperatively. The correction rate and correction loss of the Cobb angle and PO were also calculated. Results: The mean duration of surgery was 338 min, intraoperative blood loss was 1440 mL, preoperative %VC was 34.1%, FEV1.0 (%) was 91.5%, and EF was 66.1%. There were eight cases of perioperative complications. The Cobb angle and PO correction rates were 48.5% and 42.0%, respectively. We divided the patients into two groups: the L5 group, in which the LIV was L5, and the pelvis group, in which the LIV was the pelvis. The duration of surgery and PO correction rate in the pelvis group were significantly higher than those in the L5 group. Conclusions: Patients with severe NMS demonstrated severe preoperative restrictive ventilatory impairments. PSF surgery without anterior release or any intra-/preoperative traction showed satisfactory outcomes, including acceptable scoliosis correction and improved clinical findings, even in patients with extremely severe NMS. Instrumentation and fusion to the pelvis for severe scoliosis in patients with NMS showed good PO correction and low correction loss of Cobb angle and PO, but a longer duration of surgery.

Exploring the role of empathy in prolonged grief reactions to bereavement

Grief reactions to the bereavement of a close individual could involve empathy for pain, which is fundamental to social interaction. To explore whether grief symptoms interact with social relatedness to a person to whom one directs empathy to modulate the expression of empathy, we administered an empathy task to 28 bereaved adults during functional magnetic resonance imaging, in which participants were subliminally primed with facial stimuli (e.g., faces of their deceased or living relative, or a stranger), each immediately followed by a visual pain stimulus. Individuals' grief severity promoted empathy for the pain stimulus primed with the deceased's face, while it diminished the neural response to the pain stimulus primed with the face of either their living relative or a stranger in the medial frontal cortex (e.g., the right dorsal anterior cingulate cortex). Moreover, preliminary analyses showed that while the behavioral empathic response was promoted by the component of "longing" in the deceased priming condition, the neural empathic response was diminished by the component of "avoidance" in the stranger priming condition. Our results suggest an association between grief reactions to bereavement and empathy, in which grief symptoms interact with interpersonal factors to promote or diminish empathic responses to others' pain.

Relationship between physiological and parent-observed auditory over-responsiveness in children with typical development and those with autism spectrum disorders

The objective of this study was to investigate relationships between caregiver-reported sensory processing abnormalities, and the physiological index of auditory over-responsiveness evaluated using acoustic startle response measures, in children with autism spectrum disorders and typical development. Mean acoustic startle response magnitudes in response to 65-105 dB stimuli, in increments of 10 dB, were analyzed in children with autism spectrum disorders and with typical development. Average peak startle latency was also examined. We examined the relationship of these acoustic startle response measures to parent-reported behavioral sensory processing patterns in everyday situations, assessed using the Sensory Profile for all participants. Low-threshold scores on the Sensory Profile auditory section were related to acoustic startle response magnitudes at 75 and 85 dB, but not to the lower intensities of 65 dB. The peak startle latency and acoustic startle response magnitudes at low-stimuli intensities of 65 and 75 dB were significantly related to the low-threshold quadrants (sensory sensitivity and sensation avoiding) scores and to the high-threshold quadrant of sensation seeking. Our results suggest that physiological assessment provides further information regarding auditory over-responsiveness to less-intense stimuli and its relationship to caregiver-observed sensory processing abnormalities in everyday situations.