Organelle DNA degradation contributes to the efficient use of phosphate in seed plants

Mitochondria and chloroplasts (plastids) both harbour extranuclear DNA that originates from the ancestral endosymbiotic bacteria. These organelle DNAs (orgDNAs) encode limited genetic information but are highly abundant, with multiple copies in vegetative tissues, such as mature leaves. Abundant orgDNA constitutes a substantial pool of organic phosphate along with RNA in chloroplasts, which could potentially contribute to phosphate recycling when it is degraded and relocated. However, whether orgDNA is degraded nucleolytically in leaves remains unclear. In this study, we revealed the prevailing mechanism in which organelle exonuclease DPD1 degrades abundant orgDNA during leaf senescence. The DPD1 degradation system is conserved in seed plants and, more remarkably, we found that it was correlated with the efficient use of phosphate when plants were exposed to nutrient-deficient conditions. The loss of DPD1 compromised both the relocation of phosphorus to upper tissues and the response to phosphate starvation, resulting in reduced plant fitness. Our findings highlighted that DNA is also an internal phosphate-rich reservoir retained in organelles since their endosymbiotic origin

Factors influencing attitudes toward end-of-life care by care workers at special nursing homes for the elderly A Cross-sectional study in Japan

Objectives: The purpose of this study was to clarify factors influencing care workers\u27 attitudes toward end-of-life (EOL) care characteristics at special nursing homes (SNHs). Methods: A questionnaire was initially sent to 630 care workers at 19 SNHs in October 2012. Written informed consent was obtained from 253 of these workers (40.2%), who then completed and returned the questionnaires. Participants were asked to reply to questions covering demographic data, work environment, depression status, experiences/education concerning EOL, communication skills, and attitudes toward EOL care. The Japanese version of the Frommelt Attitude Toward Care of the Dying Scale, Form B (FATCOD-B-J) assessment instrument was used in the analysis of the data received. Using the median value of the FATCOD-B-J score, 130 subjects were allocated to the high score (HS) group (FATCOD-B-J?23) and 123 to the low score (LS) group (FATCOD-B-J<23). In the LS group, the odds ratios (ORs) and their 95% confidence intervals (95% CIs) of participants exhibiting relatively negative attitudes toward EOL care were calculated and adjusted for potential confounding factors using multivariate logistic regression model analysis. Results: Length of employment in the facilities of between 5 and 9 years (OR 0.37, 95% CI 0.16-0.87) as well as over 10 years (OR 0.39, 95% CI 0.16-0.96) was significantly associated with a decreased risk of placement in the LS group. Furthermore, moderate (OR 0.44, 95% CI 0.24-0.80) as well as high (OR 0.35, 95%CI 0.17-0.75) communication skills in accepting other opinions, were significantly associated with decreased risk of placement in the LS group. Conclusions: After adjustments for potential confounding variables, results indicated that extended experience as a care worker and higher communication skills in accepting other opinions were significantly associated with a reduced risk of negative attitudes toward EOL care

特別養護老人ホームにおける介護職の看取りに対する態度に影響尾及ぼす要因 : 日本における縦断研究

Aim: The aim of the present study was to clarify that the effects of accumulated experience in end-of-life care and communication skill on the attitudes of care workers’ toward end-of-life care. Methods: A study implemented 2012 to 2014. Two hundred and fifty-three questionnaires were returned (40.2%), and 170 were fully completed by care workers in special nursing homes. We sorted the responses into two groups by experience level: the experienced end-of-life care (EE) group and the inexperience end-of-life care (IE) group. Responses were also sorted by communication skill level: a high score communication (HSC) group and a low score communication (LSC) group. A two-way repeated measure analysis of variance was used for the statistical analysis. Results: The EE group was more likely to be younger (P = .04), to have a longer duration of employment (P < .001), and to have participated in an EOL care seminar in their facility (P = .02) than the IE group. Attitudes toward end-of-life care were significantly different between the EE and IE groups (df = 2, F = 3.35, P < .05). Attitudes toward end-of-life care were not significantly different when comparing the HSC and LSC groups (df = 2, F = 0.17, P = .85). The communication skill between the HSC and LSC groups differed significantly at 2012, 2013, and 2014. Conclusions: The accumulation of end-of-life care experience prompted a positive change in attitudes toward end-of-life care. Meanwhile, communication skill had no significant effect to change attitudes toward end-of-life care

A case of VEXAS syndrome (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) with decreased oxidative stress levels after oral prednisone and tocilizumab treatment

VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome has recently been described as an autoinflammatory disease associated with severe adult-onset inflammatory manifestations. The various clinical manifestations include recurrent high-grade fever, neutrophilic dermatoses, cutaneous vasculitis, chondritis of the ear and nose, pulmonary infiltrates, cytopenia, uveitis, gastrointestinal pain or inflammation, aortitis, hepatosplenomegaly, and hematological disorders. VEXAS syndrome is caused by somatic mutations of the ubiquitin-like modifier activating enzyme 1 (UBA1) gene in myeloid-lineage cells. It is characterized by vacuolated myeloid and erythroid progenitor cells seen by bone marrow biopsy. We report the case of a 64-year-old Japanese man with VEXAS syndrome. At age 63, he was referred to us with a recurrent erythema on the hands associated with a general fever of 38–40°C that had persisted for 4 or 5 days and had recurred about once a month for a year. The skin rash appeared 2 or 3 days after the onset of each fever episode. Computed tomography (CT) of the chest revealed bilateral hilar lymphadenopathy (BHL), and the mediastinal lymph nodes were swollen. Sarcoidosis was suspected but was ruled out by several tests. Laboratory examinations showed elevated inflammatory markers. Bone marrow examination showed the vacuolization of myeloid precursor cells. A skin biopsy revealed dense dermal, predominantly perivascular, infiltrates. These consisted of mature neutrophils admixed with myeloperoxidase-positive CD163-positive myeloid cells, lymphoid cells and eosinophils. Sequencing analysis identified the somatic UBA1 variant c.122T &gt; C, which results in p.Met41Thr. Treatment with oral prednisone (15 mg/day) and monthly intravenous tocilizumab injections (400 mg) completely resolved the symptoms. Neutrophils are a major source of reactive oxygen species, and the present case demonstrated numerous neutrophilic infiltrates. We hypothesize that the patient might have had elevated derivatives of reactive oxygen metabolites (d-ROMs). d-ROM quantification is a simple method for detecting hydroperoxide levels, and clinical trials have proven it useful for evaluating oxidative stress. In this study, we measured serum d-ROM before and after oral prednisone and tocilizumab treatment. The levels decreased significantly during treatment

Low-Dose Intravenous Alteplase in Wake-Up Stroke

Background and Purpose—We assessed whether lower-dose alteplase at 0.6 mg/kg is efficacious and safe for acute fluid-attenuated inversion recovery-negative stroke with unknown time of onset. Methods—This was an investigator-initiated, multicenter, randomized, open-label, blinded-end point trial. Patients met the standard indication criteria for intravenous thrombolysis other than a time last-known-well >4.5 hours (eg, wake-up stroke). Patients were randomly assigned (1:1) to receive alteplase at 0.6 mg/kg or standard medical treatment if magnetic resonance imaging showed acute ischemic lesion on diffusion-weighted imaging and no marked corresponding hyperintensity on fluid-attenuated inversion recovery. The primary outcome was a favorable outcome (90-day modified Rankin Scale score of 0–1). Results—Following the early stop and positive results of the WAKE-UP trial (Efficacy and Safety of MRI-Based Thrombolysis in Wake-Up Stroke), this trial was prematurely terminated with 131 of the anticipated 300 patients (55 women; mean age, 74.4±12.2 years). Favorable outcome was comparable between the alteplase group (32/68, 47.1%) and the control group (28/58, 48.3%; relative risk [RR], 0.97 [95% CI, 0.68–1.41]; P=0.892). Symptomatic intracranial hemorrhage within 22 to 36 hours occurred in 1/71 and 0/60 (RR, infinity [95% CI, 0.06 to infinity]; P>0.999), respectively. Death at 90 days occurred in 2/71 and 2/60 (RR, 0.85 [95% CI, 0.06–12.58]; P>0.999), respectively. Conclusions—No difference in favorable outcome was seen between alteplase and control groups among patients with ischemic stroke with unknown time of onset. The safety of alteplase at 0.6 mg/kg was comparable to that of standard treatment. Early study termination precludes any definitive conclusions

Manganese Superoxide Dismutase: Guardian of the Powerhouse

The mitochondrion is vital for many metabolic pathways in the cell, contributing all or important constituent enzymes for diverse functions such as β-oxidation of fatty acids, the urea cycle, the citric acid cycle, and ATP synthesis. The mitochondrion is also a major site of reactive oxygen species (ROS) production in the cell. Aberrant production of mitochondrial ROS can have dramatic effects on cellular function, in part, due to oxidative modification of key metabolic proteins localized in the mitochondrion. The cell is equipped with myriad antioxidant enzyme systems to combat deleterious ROS production in mitochondria, with the mitochondrial antioxidant enzyme manganese superoxide dismutase (MnSOD) acting as the chief ROS scavenging enzyme in the cell. Factors that affect the expression and/or the activity of MnSOD, resulting in diminished antioxidant capacity of the cell, can have extraordinary consequences on the overall health of the cell by altering mitochondrial metabolic function, leading to the development and progression of numerous diseases. A better understanding of the mechanisms by which MnSOD protects cells from the harmful effects of overproduction of ROS, in particular, the effects of ROS on mitochondrial metabolic enzymes, may contribute to the development of novel treatments for various diseases in which ROS are an important component

Digoxin induces inner ear damage

Auditory neuropathy is a hearing disorder in which the inner ear can detect sounds, but has a problem with sending sounds to the brain. The main pathology might be　the disorder between inner hair cell synapse and cochlear nerve. Although it is an indication for cochlear implants, there is no radical treatment yet. Therefore, a neuropathy model using animals is needed for the development of new treatment. So, we investigated digoxin-induced inner ear disorders using guinea pigs. As the results , when the digoxin was administrated into the cochlea, the number of cochlear spiral ganglion cells decreased. However, no obvious damage was observed to the cochlear hair cells. As the result of ABR (Auditory Brainstem Response), physiological dysfunction was also confirmed. As for the effect on the vestibule, the vestibular ganglion cells were damaged, but the hair cells in the otoliths and in the ampulla were not damaged. These results suggest that digoxin might be useful drug for the generation of the animal model to auditory neuropathy

Membrane potential and delta pH dependency of reverse electron transport-associated hydrogen peroxide production in brain and heart mitochondria

Succinate-driven reverse electron transport (RET) is one of the main sources of mitochondrial reactive oxygen species (mtROS) in ischemia-reperfusion injury. RET is dependent on mitochondrial membrane potential (Δψm) and transmembrane pH difference (ΔpH), components of the proton motive force (pmf); a decrease in Δψm and/or ΔpH inhibits RET. In this study we aimed to determine which component of the pmf displays the more dominant effect on RET-provoked ROS generation in isolated guinea pig brain and heart mitochondria respiring on succinate or α-glycerophosphate (α-GP). Δψm was detected via safranin fluorescence and a TPP+ electrode, the rate of H2O2 formation was measured by Amplex UltraRed, the intramitochondrial pH (pHin) was assessed via BCECF fluorescence. Ionophores were used to dissect the effects of the two components of pmf. The K+/H+ exchanger, nigericin lowered pHin and ΔpH, followed by a compensatory increase in Δψm that led to an augmented H2O2 production. Valinomycin, a K+ ionophore, at low [K+] increased ΔpH and pHin, decreased Δψm, which resulted in a decline in H2O2 formation. It was concluded that Δψm is dominant over ∆pH in modulating the succinate- and α-GP-evoked RET. The elevation of extramitochondrial pH was accompanied by an enhanced H2O2 release and a decreased ∆pH. This phenomenon reveals that from the pH component not ∆pH, but rather absolute value of pH has higher impact on the rate of mtROS formation. Minor decrease of Δψm might be applied as a therapeutic strategy to attenuate RET-driven ROS generation in ischemia-reperfusion injury