Disruption of fusion results in mitochondrial heterogeneity and dysfunction

Mitochondria undergo continual cycles of fusion and fission, and the balance of these opposing processes regulates mitochondrial morphology. Paradoxically, cells invest many resources to maintain tubular mitochondrial morphology, when reducing both fusion and fission simultaneously achieves the same end. This observation suggests a requirement for mitochondrial fusion, beyond maintenance of organelle morphology. Here, we show that cells with targeted null mutations in Mfn1 or Mfn2 retained low levels of mitochondrial fusion and escaped major cellular dysfunction. Analysis of these mutant cells showed that both homotypic and heterotypic interactions of Mfns are capable of fusion. In contrast, cells lacking both Mfn1 and Mfn2 completely lacked mitochondrial fusion and showed severe cellular defects, including poor cell growth, widespread heterogeneity of mitochondrial membrane potential, and decreased cellular respiration. Disruption of OPA1 by RNAi also blocked all mitochondrial fusion and resulted in similar cellular defects. These defects in Mfn-null or OPA1-RNAi mammalian cells were corrected upon restoration of mitochondrial fusion, unlike the irreversible defects found in fzo yeast. In contrast, fragmentation of mitochondria, without severe loss of fusion, did not result in such cellular defects. Our results showed that key cellular functions decline as mitochondrial fusion is progressively abrogated

In healthcare providers, what is the effect of mindfulness-based interventions compared with no mindfulness-based interventions on stress and burnout in 4 weeks or more?

High suicide rates and job burnout are associated with the healthcare profession, especially among physicians. The healthcare work environment is characterized by stress, demanding workloads, long shifts, and strong emotions that impact the well-being of healthcare providers (HCPs).1-3 HCPs may experience symptoms of anxiety, stress, depression, and insomnia. The well-being of healthcare providers ultimately affects medical-decision making and quality of patient care.1,4-6 Mindfulness practice has been proposed to reduce workplace stress experienced by HCPs.1,6 Mindfulness is a form of training in which an individual maintains attention on the unfolding present experience in a non-judgmental way.1 Practicing mindfulness is believed to promote attention regulation, sense of well-being, and acceptance of emotions and thoughts.1-2 Mindfulness-based interventions (MBIs), compared to no intervention, will be explored to ascertain whether they provide beneficial effects on stress and burnout in HCPs, and if so, whether these improvements are durable

Point Mutations in Centromeric Histone Induce Post-zygotic Incompatibility and Uniparental Inheritance.

The centromeric histone 3 variant (CENH3, aka CENP-A) is essential for the segregation of sister chromatids during mitosis and meiosis. To better define CENH3 functional constraints, we complemented a null allele in Arabidopsis with a variety of mutant alleles, each inducing a single amino acid change in conserved residues of the histone fold domain. Many of these transgenic missense lines displayed wild-type growth and fertility on self-pollination, but exhibited frequent post-zygotic death and uniparental inheritance when crossed with wild-type plants. The failure of centromeres marked by these missense mutation in the histone fold domain of CENH3 reproduces the genome elimination syndromes described with chimeric CENH3 and CENH3 from diverged species. Additionally, evidence that a single point mutation is sufficient to generate a haploid inducer provide a simple one-step method for the identification of non-transgenic haploid inducers in existing mutagenized collections of crop species. As proof of the extreme simplicity of this approach to create haploid-inducing lines, we performed an in silico search for previously identified point mutations in CENH3 and identified an Arabidopsis line carrying the A86V substitution within the histone fold domain. This A87V non-transgenic line, while fully fertile on self-pollination, produced postzygotic death and uniparental haploids when crossed to wild type

A targeted gene panel that covers coding, non-coding and short tandem repeat regions improves the diagnosis of patients with neurodegenerative diseases

Genetic testing for neurodegenerative diseases (NDs) is highly challenging because of genetic heterogeneity and overlapping manifestations. Targeted-gene panels (TGPs), coupled with next-generation sequencing (NGS), can facilitate the profiling of a large repertoire of ND-related genes. Due to the technical limitations inherent in NGS and TGPs, short tandem repeat (STR) variations are often ignored. However, STR expansions are known to cause such NDs as Huntington\u27s disease and spinocerebellar ataxias type 3 (SCA3). Here, we studied the clinical utility of a custom-made TGP that targets 199 NDs and 311 ND-associated genes on 118 undiagnosed patients. At least one known or likely pathogenic variation was found in 54 patients; 27 patients demonstrated clinical profiles that matched the variants; and 16 patients whose original diagnosis were refined. A high concordance of variant calling were observed when comparing the results from TGP and whole-exome sequencing of four patients. Our in-house STR detection algorithm has reached a specificity of 0.88 and a sensitivity of 0.82 in our SCA3 cohort. This study also uncovered a trove of novel and recurrent variants that may enrich the repertoire of ND-related genetic markers. We propose that a combined comprehensive TGPs-bioinformatics pipeline can improve the clinical diagnosis of NDs

Lack of complex I activity in human cells carrying a mutation in MtDNA-encoded ND4 subunit is corrected by the Saccharomyces cerevisiae NADH-quinone oxidoreductase (NDI1) gene

The gene for the single subunit, rotenone-insensitive, and flavone-sensitive internal NADH-quinone oxidoreductase of Saccharomyces cerevisiae (NDI1) can completely restore the NADH dehydrogenase activity in mutant human cells that lack the essential mitochondrial DNA (mtDNA)-encoded subunit ND4. In particular, the NDI1 gene was introduced into the nuclear genome of the human 143B.TK cell line derivative C4T, which carries a homoplasmic frameshift mutation in the ND4 gene. Two transformants with a low or high level of expression of the exogenous gene were chosen for a detailed analysis. In these cells the corresponding protein is localized in mitochondria, its NADH-binding site faces the matrix compartment as in yeast mitochondria, and in perfect correlation with its abundance restores partially or fully NADH-dependent respiration that is rotenone-insensitive, flavone-sensitive, and antimycin A-sensitive. Thus the yeast enzyme has become coupled to the downstream portion of the human respiratory chain. Furthermore, the P:O ratio with malate/glutamate-dependent respiration in the transformants is approximately two-thirds of that of the wild-type 143B.TK cells, as expected from the lack of proton pumping activity in the yeast enzyme. Finally, whereas the original mutant cell line C4T fails to grow in medium containing galactose instead of glucose, the high NDI1-expressing transformant has a fully restored capacity to grow in galactose medium. The present observations substantially expand the potential of the yeast NDI1 gene for the therapy of mitochondrial diseases involving complex I deficiency

Curated Collections for Educators: Five Key Papers on Clinical Teaching

The ability to teach in the clinical setting is of paramount importance. Clinical teaching is at the heart of medical education, irrespective of the learner’s level of training. Learners desire and need effective, competent, and thoughtful clinical teaching from their instructors. However, many clinician-educators lack formal training on this important skill and thus may provide a variable experience to their learners. Although formal training of clinician-educators is standard and required in many other countries, the United States has yet to follow suit, leaving many faculty members to fend for themselves to learn these important skills. In September 2018, the Academic Life in Emergency Medicine (ALiEM) 2018-2019 Faculty Incubator program discussed the topic of clinical teaching techniques. We gathered the titles of papers that were cited, shared, and recommended within our online discussion forum and compiled the articles pertaining to the topic of clinical teaching techniques. To augment the list, the authors did a formal literature search using the search terms “teaching techniques", "clinical teaching", "medical education", "medical students", and "residents” on Google Scholar and PubMed. Finally, we posted a call for important papers on the topic of clinical teaching techniques on Twitter. Through this process, we identified 48 core articles on the topic of clinical teaching. We conducted a modified Delphi methodology to identify the key papers on the topic. In this paper, we present the five highest-rated articles based on the relevance to junior faculty and faculty developers. This article will review and summarize the articles we found to be the most impactful to improve one’s clinical teaching skills

Personality Types, Passwords, and Cybersecurity Nudges

The goal of this research was to determine if there was any link between personality types and password usage. The SONA system and the Amazon Mechanical Turk was used to recruit users to participate in the research study. Each user’s personality was obtained through a survey. The survey asked users to enter a strong password. Passwords were scored from zero to four with zero being classified as “too guessable” and four being classified as “very unguessable.” A second aspect of this research was to determine if a targeted message, based on the personality, had an effect on password behavior

Thermal diffusion cloud chamber - new criteria for proper orientation

We report results of new nucleation experiments involving 1-pentanol with hydrogen as the background gas utilizing the high-pressure diffusion cloud chamber (HPCC). We discuss the important issue of buoyancy-driven convective motion and cloud chamber operation, and we focus on the lower total pressure limit required for stable chamber operation. We provide, for the first time, an empirical procedure for determining the lower total pressure limit

Communication, Relationships, and Priorities: Parental and Provider Experiences of Infant Feeding Support on the Northeast Avalon

Infant feeding is a subject of great interest and importance to those who advocate for the health and wellness of parents and babies. The infant feeding journey begins in pregnancy, as most pregnant individuals decide how they intend to feed their child before they give birth. Moreover, acquiring knowledge about the realities of infant feeding before birth is a key to success, however defined. Drawing on a longitudinal study in the Northeast Avalon region of Newfoundland, this report presents seven recommended actions to better support infant feeding, from a perspective within a province with the lowest breastfeeding rates in Canada. Informed by feminist participatory action research, the recommendations may be insightful for other regions struggling to better support infant feeding

Maintenance therapy in advanced non-small cell lung cancer: A prime-time for change?

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