Predictors of Severe Acute Respiratory Syndrome Coronavirus 2 Infection Following High-Risk Exposure.

BACKGROUND: Non-pharmaceutical interventions (NPIs) are recommended for COVID-19 prevention. However, the effectiveness of NPIs in preventing SARS-CoV-2 transmission remains poorly quantified. METHODS: We conducted a test-negative design case-control study enrolling cases (testing positive for SARS-CoV-2) and controls (testing negative) with molecular SARS-CoV-2 diagnostic test results reported to California Department of Public Health between 24 February-12 November, 2021. We used conditional logistic regression to estimate adjusted odds ratios (aORs) of case status among participants who reported contact with an individual known or suspected to have been infected with SARS-CoV-2 ("high-risk exposure") ≤14 days before testing. RESULTS: 751 of 1448 cases (52%) and 255 of 1443 controls (18%) reported high-risk exposures ≤14 days before testing. Adjusted odds of case status were 3.02-fold (95% confidence interval: 1.75-5.22) higher when high-risk exposures occurred with household members (vs. other contacts), 2.10-fold (1.05-4.21) higher when exposures occurred indoors (vs. outdoors only), and 2.15-fold (1.27-3.67) higher when exposures lasted ≥3 hours (vs. shorter durations) among unvaccinated and partially-vaccinated individuals; excess risk associated with such exposures was mitigated among fully-vaccinated individuals. Cases were less likely than controls to report mask usage during high-risk exposures (aOR = 0.50 [0.29-0.85]). The adjusted odds of case status was lower for fully-vaccinated (aOR = 0.25 [0.15-0.43]) participants compared to unvaccinated participants. Benefits of mask usage were greatest among unvaccinated and partially-vaccinated participants, and in interactions involving non-household contacts or interactions occurring without physical contact. CONCLUSIONS: NPIs reduced the likelihood of SARS-CoV-2 infection following high-risk exposure. Vaccine effectiveness was substantial for partially and fully vaccinated persons.

Serological Profiling of Group A Streptococcus Infections in Acute Rheumatic Fever.

Rheumatic fever is a serious post-infectious sequela of group A Streptococcus (GAS). Prior GAS exposures were mapped in sera using a large panel of M-type specific peptides. Rheumatic fever patients had serological evidence of significantly more GAS exposures than matched controls suggesting immune priming by repeat infections contributes to pathogenesis.

Engineered RebH Halogenase Variants Demonstrating a Specificity Switch from Tryptophan towards Novel Indole Compounds.

Activating industrially important aromatic hydrocarbons by installing halogen atoms is extremely important in organic synthesis and often improves the pharmacological properties of drug molecules. To this end, tryptophan halogenase enzymes are potentially valuable tools for regioselective halogenation of arenes, including various industrially important indole derivatives and similar scaffolds. Although endogenous enzymes show reasonable substrate scope towards indole compounds, their efficacy can often be improved by engineering. Using a structure-guided semi-rational mutagenesis approach, we have developed two RebH variants with expanded biocatalytic repertoires that can efficiently halogenate several novel indole substrates and produce important pharmaceutical intermediates. Interestingly, the engineered enzymes are completely inactive towards their natural substrate tryptophan in spite of their high tolerance to various functional groups in the indole ring. Computational modelling and molecular dynamics simulations provide mechanistic insights into the role of gatekeeper residues in the substrate binding site and the dramatic switch in substrate specificity when these are mutated.

Post-Visit Patient Understanding About Newly Prescribed Medications.

BACKGROUND: Good patient understanding of basic medication-related information such as directions for use and side effects promotes medication adherence, but information is lacking about how well patients understand basic medication-related information after their office visits. OBJECTIVE: The purpose of this study is to investigate post-visit patient understanding about newly prescribed medications. DESIGN: Secondary mixed methods analysis comparing patient survey responses about newly prescribed medications to information conveyed by physicians during office visits (from audio recordings of office visits). PARTICIPANTS: Eighty-one patients aged 50 and older who discussed newly prescribed medications during an outpatient office visit. MAIN MEASURES: Accurate patient identification of medication dose, number of pills, frequency of use, duration of use, and potential side effects. KEY RESULTS: The 81 patients in this study received 111 newly prescribed medications. For over 70% of all newly prescribed medications, patients correctly identified the number of pills, frequency of use, duration of use, and dose, regardless of whether the physician mentioned the information during the office visit. However, for 34 of 62 medications (55%) for which side effects were not conveyed and 11 of 49 medications (22%) for which physicians discussed side effects, patients reported that the medication lacked side effects. Analysis of transcribed office visits showed that potential reasons for this finding included failure of physicians to mention or to use the term "side effects" during visits, the prescription of multiple medications during the visit, and lack of patient engagement in the conversation. CONCLUSIONS: Many patients correctly identified information related to directions for taking a newly prescribed medication, even without physician counseling, but when physicians failed to convey potential medication side effects, many assumed that a medication had no side effects. It may be sufficient for physicians to provide written information about medication directions and dosing, and tailor their limited time to discussing medication side effects.

Association between post-hospital clinic and telephone follow-up provider visits with 30-day readmission risk in an integrated health system.

BACKGROUND: Follow-up visits with clinic providers after hospital discharge may not be feasible for some patients due to functional limitations, transportation challenges, need for physical distancing, or fear of exposure especially during the current COVID-19 pandemic. METHODS: The aim of the study was to determine the effects of post-hospital clinic (POSH) and telephone (TPOSH) follow-up provider visits versus no visit on 30-day readmission. We used a retrospective cohort design based on data from 1/1/2017 to 12/31/2019 on adult patients (n = 213,513) discharged home from 15 Kaiser Permanente Southern California hospitals. Completion of POSH or TPOSH provider visits within 7 days of discharge was the exposure and all-cause 30-day inpatient and observation stay readmission was the primary outcome. We used matching weights to balance the groups and Fine-Gray subdistribution hazard model to assess for readmission risk. RESULTS: Unweighted all-cause 30-day readmission rate was highest for patients who completed a TPOSH (17.3%) followed by no visit (14.2%), non-POSH (evaluation and management visits that were not focused on the hospitalization: 13.6%) and POSH (12.6%) visits. The matching weighted models showed that the effects of POSH and TPOSH visits varied across patient subgroups. For high risk (LACE 11+) medicine patients, both POSH (HR: 0.77, 95% CI: 0.71, 0.85, P < .001) and TPOSH (HR: 0.91, 95% CI: 0.83, 0.99, P = .03) were associated with 23 and 9% lower risk of 30-day readmission, respectively, compared to no visit. For medium to low risk medicine patients (LACE< 11) and all surgical patients regardless of LACE score or age, there were no significant associations for either visit type with risk of 30-day readmission. CONCLUSIONS: Post-hospital telephone follow-up provider visits had only modest effects on 30-day readmission in high-risk medicine patients compared to clinic visits. It remains to be determined if greater use and comfort with virtual visits by providers and patients as a result of the pandemic might improve the effectiveness of these encounters.

Metabolic pathway analyses identify proline biosynthesis pathway as a promoter of liver tumorigenesis.

BACKGROUND & AIM: Under the regulation of various oncogenic pathways, cancer cells undergo adaptive metabolic programming to maintain specific metabolic states that support their uncontrolled proliferation. As it has been difficult to directly and effectively inhibit oncogenic signaling cascades with pharmaceutical compounds, focusing on the downstream metabolic pathways that enable indefinite growth may provide therapeutic opportunities. Thus, we sought to characterize metabolic changes in hepatocellular carcinoma (HCC) development and identify metabolic targets required for tumorigenesis. METHODS: We compared gene expression profiles of Morris Hepatoma (MH3924a) and DEN (diethylnitrosamine)-induced HCC models to those of liver tissues from normal and rapidly regenerating liver models, and performed gain- and loss-of-function studies of the identified gene targets for their roles in cancer cell proliferation in vitro and in vivo. RESULTS: The proline biosynthetic enzyme PYCR1 (pyrroline-5-carboxylate reductase 1) was identified as one of the most upregulated genes in the HCC models. Knockdown of PYCR1 potently reduced cell proliferation of multiple HCC cell lines in vitro and tumor growth in vivo. Conversely, overexpression of PYCR1 enhanced the proliferation of the HCC cell lines. Importantly, PYCR1 expression was not elevated in the regenerating liver, and KD or overexpression of PYCR1 had no effect on proliferation of non-cancerous cells. Besides PYCR1, we found that additional proline biosynthetic enzymes, such as ALDH18A1, were upregulated in HCC models and also regulated HCC cell proliferation. Clinical data demonstrated that PYCR1 expression was increased in HCC, correlated with tumor grade, and was an independent predictor of clinical outcome. CONCLUSION: Enhanced expression of proline biosynthetic enzymes promotes HCC cell proliferation. Inhibition of PYCR1 or ALDH18A1 may be a novel therapeutic strategy to target HCC. LAY SUMMARY: Even with the recently approved immunotherapies against liver cancer, currently available medications show limited clinical benefits or efficacy in the majority of patients. As such, it remains a top priority to discover new targets for effective liver cancer treatment. Here, we identify a critical role for the proline biosynthetic pathway in liver cancer development, and demonstrate that targeting key proteins in the pathway, namely PYCR1 and ALDH18A1, may be a novel therapeutic strategy for liver cancer.

Systems immunology reveals a linked IgG3-C4 response in patients with acute rheumatic fever.

Acute rheumatic fever (ARF) and chronic rheumatic heart disease (RHD) are autoimmune sequelae of a Group A streptococcal infection with significant global mortality and poorly understood pathogenesis. Immunoglobulin and complement deposition were observed in ARF/RHD valve tissue over 50 years ago, yet contemporary investigations have been lacking. This study applied systems immunology to investigate the relationships between the complement system and immunoglobulin in ARF. Patients were stratified by C-reactive protein (CRP) concentration into high (≥10 µg mL-1 ) and low (<10 µg mL-1 ) groups to distinguish those with clinically significant inflammatory processes from those with abating inflammation. The circulating concentrations of 17 complement factors and six immunoglobulin isotypes and subclasses were measured in ARF patients and highly matched healthy controls using multiplex bead-based immunoassays. An integrative statistical approach combining feature selection and principal component analysis revealed a linked IgG3-C4 response in ARF patients with high CRP that was absent in controls. Strikingly, both IgG3 and C4 were elevated above clinical reference ranges, suggesting these features are a marker of ARF-associated inflammation. Humoral immunity in response to M protein, an antigen implicated in ARF pathogenesis, was completely polarized to IgG3 in the patient group. Furthermore, the anti-M-protein IgG3 response was correlated with circulating IgG3 concentration, highlighting a potential role for this potent immunoglobulin subclass in disease. In conclusion, a linked IgG3-C4 response appears important in the initial, inflammatory stage of ARF and may have immediate utility as a clinical biomarker given the lack of specific diagnostic tests currently available.

Employing standardized risk assessment in pretrial release decisions: Association with criminal justice outcomes and racial equity.

OBJECTIVE: We examined efforts by a Mississippi court to base pretrial release decisions on risk assessment rather than primarily on bond. HYPOTHESES: (a) Pretrial detention will be shorter than that associated with prevailing bond practices in the same counties. (b) Rearrest rates will be lower than a similar pretrial population in a nearby southern state. (c) False positive rates for predicting rearrests will be higher for African American than Caucasian participants. (d) Pretrial detention will be longer for African American participants because of higher risk scores or assessment overrides. METHOD: Pretrial defendants (N = 521) completed the Risk and Needs Triage (RANT) within 2 weeks of arrest, and outcomes examined included the length of pretrial detention, index case dispositions, and rearrest rates. RESULTS: (a) Pretrial detention averaged approximately 60 days compared with prevailing detentions averaging approximately 90 and 180 days in the same counties. (b) Pretrial rearrest rates were 17 percentage points higher than a similar pretrial population; however, representative comparison data are unavailable to confidently measure recidivism impacts. (c) Positive predictive power did not differ by race in predicting pretrial rearrests, SE = .04, 95% CI [.11, -.06], z = .61, p = .54, d = .08. (d) Despite comparable risk scores, African American participants were detained significantly longer than Caucasian participants (M = 60.92 vs. 45.58 days), p = .038, d = .18, 95% CI [.01, .36], and were less likely to receive a diversion opportunity (11% vs. 23%), p = .009, V = .17. CONCLUSION: The observational design precludes causal conclusions; however, risk assessment was associated with shorter pretrial detention than prevailing bond practices with no racial disparities in risk prediction. Greater attention to risk assessment may reduce racial inequities in pretrial conditions. Representative comparison data are needed to measure the recidivism impacts of pretrial reform initiatives. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Forward and reverse mutations in stages of cancer development.

BACKGROUND: Massive occurrences of interstitial loss of heterozygosity (LOH) likely resulting from gene conversions were found by us in different cancers as a type of single-nucleotide variations (SNVs), comparable in abundance to the commonly investigated gain of heterozygosity (GOH) type of SNVs, raising the question of the relationships between these two opposing types of cancer mutations. METHODS: In the present study, SNVs in 12 tetra sample and 17 trio sample sets from four cancer types along with copy number variations (CNVs) were analyzed by AluScan sequencing, comparing tumor with white blood cells as well as tissues vicinal to the tumor. Four published "nontumor"-tumor metastasis trios and 246 pan-cancer pairs analyzed by whole-genome sequencing (WGS) and 67 trios by whole-exome sequencing (WES) were also examined. RESULTS: Widespread GOHs enriched with CG-to-TG changes and associated with nearby CNVs and LOHs enriched with TG-to-CG changes were observed. Occurrences of GOH were 1.9-fold higher than LOH in "nontumor" tissues more than 2 cm away from the tumors, and a majority of these GOHs and LOHs were reversed in "paratumor" tissues within 2 cm of the tumors, forming forward-reverse mutation cycles where the revertant LOHs displayed strong lineage effects that pointed to a sequential instead of parallel development from "nontumor" to "paratumor" and onto tumor cells, which was also supported by the relative frequencies of 26 distinct classes of CNVs between these three types of cell populations. CONCLUSIONS: These findings suggest that developing cancer cells undergo sequential changes that enable the "nontumor" cells to acquire a wide range of forward mutations including ones that are essential for oncogenicity, followed by revertant mutations in the "paratumor" cells to avoid growth retardation by excessive mutation load. Such utilization of forward-reverse mutation cycles as an adaptive mechanism was also observed in cultured HeLa cells upon successive replatings. An understanding of forward-reverse mutation cycles in cancer development could provide a genomic basis for improved early diagnosis, staging, and treatment of cancers.

Addressing the challenges restoring clinical services during the COVID-19 pandemic by harnessing the alignment of clinical and management leadership: an example from a large colorectal service.

BACKGROUND: The COVID-19 pandemic has posed the greatest operational challenge to the English National Health Service since its inception. Elective surgical services have struggled due to the need to protect both staff and patients from viral exposure, and perioperative COVID-19 infection has been associated with significant excess mortality. INTERVENTIONS: In this brief report, we describe how through necessity, it has provided an opportunity to redesign services for the benefit of both patients and organisations, with attendant improvement in activity compared with prepandemic metrics. We present the experience of a large district general hospital, using the department of colorectal surgery as a case study, in responding to the pandemic by restoring services and achieving improved short-term outcomes and processes in newly redesignated facilities. CONCLUSIONS: These reorganised surgical services represent a 'silver lining' of the pandemic. Clinician-led service restructuring, with positive engagement with staff at all levels, has not only addressed backlogs of urgent elective patients in a safe environment, but has also led to patient benefits and high levels of patient and staff satisfaction.

Conserved multi-tissue transcriptomic adaptations to exercise training in humans and mice.

Physical activity is associated with beneficial adaptations in human and rodent metabolism. We studied over 50 complex traits before and after exercise intervention in middle-aged men and a panel of 100 diverse strains of female mice. Candidate gene analyses in three brain regions, muscle, liver, heart, and adipose tissue of mice indicate genetic drivers of clinically relevant traits, including volitional exercise volume, muscle metabolism, adiposity, and hepatic lipids. Although ∼33% of genes differentially expressed in skeletal muscle following the exercise intervention are similar in mice and humans independent of BMI, responsiveness of adipose tissue to exercise-stimulated weight loss appears controlled by species and underlying genotype. We leveraged genetic diversity to generate prediction models of metabolic trait responsiveness to volitional activity offering a framework for advancing personalized exercise prescription. The human and mouse data are publicly available via a user-friendly Web-based application to enhance data mining and hypothesis development.

Indole and azaindole halogenation catalyzed by the RebH enzyme variant 3-LSR utilizing co-purified E. coli reductase.

Biocatalytic C-H halogenation is becoming increasingly attractive due to excellent catalyst-controlled selectivity and environmentally benign reaction conditions. Significant efforts have been made on enzymatic halogenation of industrial arenes in a cost-effective manner. Here we report an unprecedented enzymatic halogenation of a panel of industrially important indole, azaindole and anthranilamide derivatives using a thermostable RebH variant without addition of any external flavin reductase enzyme. The reactions were catalyzed by the RebH variant 3-LSR enzyme with the help of a co-purified E. coli reductase identified as alkyl hydroperoxide reductase F (AhpF).

Halogenation of Peptides and Proteins Using Engineered Tryptophan Halogenase Enzymes.

Halogenation of bioactive peptides via incorporation of non-natural amino acid derivatives during chemical synthesis is a common strategy to enhance functionality. Bacterial tyrptophan halogenases efficiently catalyze regiospecific halogenation of the free amino acid tryptophan, both in vitro and in vivo. Expansion of their substrate scope to peptides and proteins would facilitate highly-regulated post-synthesis/expression halogenation. Here, we demonstrate novel in vitro halogenation (chlorination and bromination) of peptides by select halogenase enzymes and identify the C-terminal (G/S)GW motif as a preferred substrate. In a first proof-of-principle experiment, we also demonstrate chemo-catalyzed derivatization of an enzymatically chlorinated peptide, albeit with low efficiency. We further rationally derive PyrH halogenase mutants showing improved halogenation of the (G/S)GW motif, both as a free peptide and when genetically fused to model proteins with efficiencies up to 90%.

A Slam-dependent hemophore contributes to heme acquisition in the bacterial pathogen Acinetobacter baumannii.

Nutrient acquisition systems are often crucial for pathogen growth and survival during infection, and represent attractive therapeutic targets. Here, we study the protein machinery required for heme uptake in the opportunistic pathogen Acinetobacter baumannii. We show that the hemO locus, which includes a gene encoding the heme-degrading enzyme, is required for high-affinity heme acquisition from hemoglobin and serum albumin. The hemO locus includes a gene coding for a heme scavenger (HphA), which is secreted by a Slam protein. Furthermore, heme uptake is dependent on a TonB-dependent receptor (HphR), which is important for survival and/or dissemination into the vasculature in a mouse model of pulmonary infection. Our results indicate that A. baumannii uses a two-component receptor system for the acquisition of heme from host heme reservoirs.

A systematic review on the anxiolytic effects of aromatherapy on rodents under experimentally induced anxiety models.

PURPOSE: We reviewed studies from 1999 to 2009 on anxiolytic effects of different essential oils toward rodents in anxiety-related behavioral models. METHOD: Journal papers that evaluated the anxiolytic effects of essential oils for rodents were extracted from available electronic data bases. RESULTS: The results based on 14 studies showed that different rodent species were recruited including ICR mice and Swiss mice. Most of studies applied the Elevated Plus Maze (EPM) as the animal behavioral model. Lavender oil was the most popular within the 14 studies. Lavender and rose oils were found to be effective in some of the studies. Only one study reported the underlying neurophysiological mechanism in terms of concentrations of emotionally related neuro-transmitters such as dopamine, serotonin, and their derivatives, in various brain regions. CONCLUSION: Some essential oils are found to be effective to induce anxiolytic effect in rodents under different animal anxiety models. However, more standardized experimental procedures and outcome measures are needed in future studies. Translational research to human subjects is also recommended.

Early postoperative MRI and detection of residual adenoma after transsphenoidal pituitary surgery.

OBJECTIVE: Current practice guidelines recommend delayed (≥ 3 months after operation) postoperative MRI after transsphenoidal surgery for pituitary adenomas, although this practice defers obtaining important information, such as the presence of a residual adenoma, that might influence patient management during the perioperative period. In this study, the authors compared detection of residual adenomas by means of early postoperative (EPO) MRI (< 48 hours postsurgery) with both surgeon intraoperative assessment and late postoperative (LPO) MRI at 3 months. METHODS: Adult patients who underwent microscopic transsphenoidal surgery for pituitary adenomas with MRI preoperatively, < 48 hours after the operation, 3 months postoperatively, and yearly for 4 years were included. The presence or absence of residual tumor was assessed intraoperatively by a single surgeon and postoperatively by 2 neuroradiologists blinded to the intraoperative assessment and other postoperative imaging studies. The presence of residual tumor was confirmed by reresection, tumor growth on imaging, or hormonal evidence. Interreader reliability was calculated at each imaging time point. Specificity, sensitivity, positive predictive value, and negative predictive value for EPO and LPO imaging and intraoperative assessment were determined. RESULTS: In total, 102 consecutive patients who underwent microscopic transsphenoidal resection of a pituitary adenoma were included. Eighteen patients (18%) had confirmed residual tumors (12 confirmed by tumor growth, 5 by surgery, and 1 by biochemical evidence of persistent disease). Interreader reliability for detecting residual tumor on EPO MRI was almost perfect (κ = 0.88) and significantly higher than that for LPO MRI (κ = 0.69, p = 0.03). EPO MRI was highly specific for residual tumor (98%), a finding similar to that for intraoperative assessment (99%, p = 0.60) and significantly higher than that for LPO MRI (81%, p < 0.001). Notably, EPO MRI was significantly more sensitive for residual tumor (100%) than both intraoperative assessment (78%, p = 0.04) and LPO MRI (78%, p = 0.04). EPO MRI had a 100% negative predictive value and was used to find 4 residual tumors that were not identified intraoperatively. Residual tumors found on EPO MRI allowed for reresection during the same hospitalization for 3 patients. CONCLUSIONS: EPO MRI after transsphenoidal pituitary surgery can be reliably interpreted and has greater sensitivity for detecting residual tumor than intraoperative assessment and LPO MRI. This result challenges current guidelines stating that delayed postoperative imaging is preferable to early imaging. Pituitary surgeons should consider performing EPO MRI either in addition to or instead of delayed imaging.

The change of gravity vector induces short-term phosphoproteomic alterations in Arabidopsis.

Plants can sense the gravitational force. When plants perceive a change in this natural force, they tend to reorient their organs with respect to the direction of the gravity vector, i.e., the shoot stem curves up. In the present study, we performed a 4C quantitative phosphoproteomics to identify those altered protein phosphosites resulting from 150 s of reorientation of Arabidopsis plants on earth. A total of 5556 phosphopeptides were identified from the gravistimulated Arabidopsis. Quantification based on the 15N-stable isotope labeling in Arabidopsis (SILIA) and computational analysis of the extracted ion chromatogram (XIC) of phosphopeptides showed eight and five unique PTM peptide arrays (UPAs) being up- and down-regulated, respectively, by gravistimulation. Among the 13 plant reorientation-responsive protein groups, many are related to the cytoskeleton dynamic and plastid movement. Interestingly, the most gravistimulation-responsive phosphosites are three serine residues, S350, S376, and S410, of a blue light receptor Phototropin 1 (PHOT1). The immunoblots experiment confirmed that the change of gravity vector indeed affected the phosphorylation level of S410 in PHOT1. The functional role of PHOT1 in gravitropic response was further validated with gravicurvature measurement in the darkness of both the loss-of-function double mutant phot1phot2 and its complementary transgenic plant PHOT1/phot1phot2. SIGNIFICANCE: The organs of sessile organisms, plants, are able to move in response to environmental stimuli, such as gravity vector, touch, light, water, or nutrients, which is termed tropism. For instance, the bending of plant shoots to the light source is called phototropism. Since all plants growing on earth are continuously exposed to the gravitational field, plants receive the mechanical signal elicited by the gravity vector change and convert it into plant morphogenesis, growth, and development. Past studies have resulted in various hypotheses for gravisensing, but our knowledge about how the signal of gravity force is transduced in plant cells is still minimal. In the present study, we performed a SILIA-based 4C quantitative phosphoproteomics on 150-s gravistimulated Arabidopsis seedlings to explore the phosphoproteins involved in the gravitropic response. Our data demonstrated that such a short-term reorientation of Arabidopsis caused changes in phosphorylation of cytoskeleton structural proteins like Chloroplast Unusual Positioning1 (CHUP1), Patellin3 (PATL3), and Plastid Movement Impaired2 (PMI2), as well as the blue light receptor Phototropin1 (PHOT1). These results suggested that protein phosphorylation plays a crucial role in gravisignaling, and two primary tropic responses of plants, gravitropism and phototropism, may share some common components and signaling pathways. We expect that the phosphoproteins detected from this study will facilitate the subsequent molecular and cellular studies on the mechanism underlying the signal transduction in plant gravitropic response.

Mitochondrial Dysfunction Is an Early Consequence of Partial or Complete Dystrophin Loss in mdx Mice.

Duchenne muscular dystrophy (DMD) is characterized by rapid wasting of skeletal muscle. Mitochondrial dysfunction is a well-known pathological feature of DMD. However, whether mitochondrial dysfunction occurs before muscle fiber damage in DMD pathology is not well known. Furthermore, the impact upon heterozygous female mdx carriers (mdx/+), who display dystrophin mosaicism, has received little attention. We hypothesized that dystrophin deletion leads to mitochondrial dysfunction, and that this may occur before myofiber necrosis. As a secondary complication to mitochondrial dysfunction, we also hypothesized metabolic abnormalities prior to the onset of muscle damage. In this study, we detected aberrant mitochondrial morphology, reduced cristae number, and large mitochondrial vacuoles from both male and female mdx mice prior to the onset of muscle damage. Furthermore, we systematically characterized mitochondria during disease progression starting before the onset of muscle damage, noting additional changes in mitochondrial DNA copy number and regulators of mitochondrial size. We further detected mild metabolic and mitochondrial impairments in female mdx carrier mice that were exacerbated with high-fat diet feeding. Lastly, inhibition of the strong autophagic program observed in adolescent mdx male mice via administration of the autophagy inhibitor leupeptin did not improve skeletal muscle pathology. These results are in line with previous data and suggest that before the onset of myofiber necrosis, mitochondrial and metabolic abnormalities are present within the mdx mouse.

Age-induced mitochondrial DNA point mutations are inadequate to alter metabolic homeostasis in response to nutrient challenge.

Mitochondrial dysfunction is frequently associated with impairment in metabolic homeostasis and insulin action, and is thought to underlie cellular aging. However, it is unclear whether mitochondrial dysfunction is a cause or consequence of insulin resistance in humans. To determine the impact of intrinsic mitochondrial dysfunction on metabolism and insulin action, we performed comprehensive metabolic phenotyping of the polymerase gamma (PolG) D257A "mutator" mouse, a model known to accumulate supraphysiological mitochondrial DNA (mtDNA) point mutations. We utilized the heterozygous PolG mutator mouse (PolG+/mut ) because it accumulates mtDNA point mutations ~ 500-fold > wild-type mice (WT), but fails to develop an overt progeria phenotype, unlike PolGmut/mut animals. To determine whether mtDNA point mutations induce metabolic dysfunction, we examined male PolG+/mut mice at 6 and 12 months of age during normal chow feeding, after 24-hr starvation, and following high-fat diet (HFD) feeding. No marked differences were observed in glucose homeostasis, adiposity, protein/gene markers of metabolism, or oxygen consumption in muscle between WT and PolG+/mut mice during any of the conditions or ages studied. However, proteomic analyses performed on isolated mitochondria from 12-month-old PolG+/mut mouse muscle revealed alterations in the expression of mitochondrial ribosomal proteins, electron transport chain components, and oxidative stress-related factors compared with WT. These findings suggest that mtDNA point mutations at levels observed in mammalian aging are insufficient to disrupt metabolic homeostasis and insulin action in male mice.

The impact of exercise on mitochondrial dynamics and the role of Drp1 in exercise performance and training adaptations in skeletal muscle.

OBJECTIVE: Mitochondria are organelles primarily responsible for energy production, and recent evidence indicates that alterations in size, shape, location, and quantity occur in response to fluctuations in energy supply and demand. We tested the impact of acute and chronic exercise on mitochondrial dynamics signaling and determined the impact of the mitochondrial fission regulator Dynamin related protein (Drp)1 on exercise performance and muscle adaptations to training. METHODS: Wildtype and muscle-specific Drp1 heterozygote (mDrp1+/-) mice, as well as dysglycemic (DG) and healthy normoglycemic men (control) performed acute and chronic exercise. The Hybrid Mouse Diversity Panel, including 100 murine strains of recombinant inbred mice, was used to identify muscle Dnm1L (encodes Drp1)-gene relationships. RESULTS: Endurance exercise impacted all aspects of the mitochondrial life cycle, i.e. fission-fusion, biogenesis, and mitophagy. Dnm1L gene expression and Drp1Ser616 phosphorylation were markedly increased by acute exercise and declined to baseline during post-exercise recovery. Dnm1L expression was strongly associated with transcripts known to regulate mitochondrial metabolism and adaptations to exercise. Exercise increased the expression of DNM1L in skeletal muscle of healthy control and DG subjects, despite a 15% ↓(P = 0.01) in muscle DNM1L expression in DG at baseline. To interrogate the role of Dnm1L further, we exercise trained male mDrp1+/- mice and found that Drp1 deficiency reduced muscle endurance and running performance, and altered muscle adaptations in response to exercise training. CONCLUSION: Our findings highlight the importance of mitochondrial dynamics, specifically Drp1 signaling, in the regulation of exercise performance and adaptations to endurance exercise training.