The second messenger cyclic AMP (cAMP) can either stimulate or inhibit programmed cell death (apoptosis). Here, we review examples of cell types that show pro‐apoptotic or anti‐apoptotic responses to ...increases in cAMP. We also show that cells can have both such responses, although predominantly having one or the other. Protein kinase A (PKA)‐promoted changes in phosphorylation and gene expression can mediate pro‐apoptotic responses, such as in murine S49 lymphoma cells, based on evidence that mutants lacking PKA fail to undergo cAMP‐promoted, mitochondria‐dependent apoptosis. Mechanisms for the anti‐apoptotic response to cAMP likely involve Epac (Exchange protein activated by cAMP), a cAMP‐regulated effector that is a guanine nucleotide exchange factor (GEF) for the low molecular weight G‐protein, Rap1. Therapeutic approaches that activate PKA‐mediated pro‐apoptosis or block Epac‐mediated anti‐apoptotisis may provide a means to enhance cell killing, such as in certain cancers. In contrast, efforts to block PKA or stimulate Epac have the potential to be useful in diseases settings (such as heart failure) associated with cAMP‐promoted apoptosis.
Myasthenia gravis (MG), an autoimmune neuromuscular disorder, may be a risk factor for severe COVID-19. We conducted an observational retrospective study with 15 consecutive adult MG patients ...admitted with COVID-19 at four hospitals in São Paulo, Brazil. Most patients with MG hospitalized for COVID-19 had severe courses of the disease: 87% were admitted in the intensive care unit, 73% needed mechanical ventilation, and 30% died. Immunoglobulin use and the plasma exchange procedure were safe. Immunosuppressive therapy seems to be associated with better outcomes, as it might play a protective role.
Proteins populate a manifold in the high-dimensional sequence space whose geometrical structure guides their natural evolution. Leveraging recently-developed structure prediction tools based on ...transformer models, we first examine the protein sequence landscape as defined by an effective energy that is a proxy of sequence foldability. This landscape shares characteristics with optimization challenges encountered in machine learning and constraint satisfaction problems. Our analysis reveals that natural proteins predominantly reside in wide, flat minima within this energy landscape. To investigate further, we employ statistical mechanics algorithms specifically designed to explore regions with high local entropy in relatively flat landscapes. Our findings indicate that these specialized algorithms can identify valleys with higher entropy compared to those found using traditional methods such as Monte Carlo Markov Chains. In a proof-of-concept case, we find that these highly entropic minima exhibit significant similarities to natural sequences, especially in critical key sites and local entropy. Additionally, evaluations through Molecular Dynamics suggests that the stability of these sequences closely resembles that of natural proteins. Our tool combines advancements in machine learning and statistical physics, providing new insights into the exploration of sequence landscapes where wide, flat minima coexist alongside a majority of narrower minima.
The innate immune response of Drosophila melanogaster is governed by a complex set of signaling pathways that trigger antimicrobial peptide (AMP) production, phagocytosis, melanization, and ...encapsulation. Although immune responses against both bacteria and fungi have been demonstrated in Drosophila, identification of an antiviral response has yet to be found. To investigate what responses Drosophila mounts against a viral infection, we have developed an in vivo Drosophila X virus (DXV)-based screening system that identifies altered sensitivity to viral infection by using DXV's anoxia-induced death pathology. Using this system to screen flies with mutations in genes with known or suggested immune activity, we identified the Toll pathway as a vital part of the Drosophila antiviral response. Inactivation of this pathway instigated a rapid onset of anoxia induced death in infected flies and increases in viral titers compared to those in WT flies. Although constitutive activation of the pathway resulted in similar rapid onset of anoxia sensitivity, it also resulted in decreased viral titer. Additionally, AMP genes were induced in response to viral infection similar to levels observed during Escherichia coli infection. However, enhanced expression of single AMPs did not alter resistance to viral infection or viral titer levels, suggesting that the main antiviral response is cellular rather than humoral. Our results show that the Toll pathway is required for efficient inhibition of DXV replication in Drosophila. Additionally, our results demonstrate the validity of using a genetic approach to identify genes and pathways used in viral innate immune responses in Drosophila.
Abstract
Mitochondria undergo continuous cycles of fusion and fission in response to physiopathological stimuli. The key player in mitochondrial fission is dynamin-related protein 1 (DRP1), a ...cytosolic protein encoded by dynamin 1-like (DNM1L) gene, which relocalizes to the outer mitochondrial membrane, where it assembles, oligomerizes and drives mitochondrial division upon guanosine-5′-triphosphate (GTP) hydrolysis. Few DRP1 mutations have been described so far, with patients showing complex and variable phenotype ranging from early death to encephalopathy and/or optic atrophy. The disease is the consequence of defective mitochondrial fission due to faulty DRP1 function. However, the underlying molecular mechanisms and the functional consequences at mitochondrial and cellular level remain elusive. Here we report on a 5-year-old girl presenting psychomotor developmental delay, global hypotonia and severe ataxia due to axonal sensory neuropathy harboring a novel de novo heterozygous missense mutation in the GTPase domain of DRP1 (NM_012062.3:c.436G>A, NP_036192.2: p.D146N variant in DNM1L). Patient’s fibroblasts show hyperfused/balloon-like giant mitochondria, highlighting the importance of D146 residue for DRP1 function. This dramatic mitochondrial rearrangement phenocopies what observed overexpressing DRP1-K38A, a well-known experimental dominant negative version of DRP1. In addition, we demonstrated that p.D146N mutation has great impact on peroxisomal shape and function. The p.D146N mutation compromises the GTPase activity without perturbing DRP1 recruitment or assembly, causing decreased mitochondrial and peroxisomal turnover. In conclusion, our findings highlight the importance of sensory neuropathy in the clinical spectrum of DRP1 variants and, for the first time, the impact of DRP1 mutations on mitochondrial turnover and peroxisomal functionality.
Mutations in the LAMA2 gene affect the production of the α2 subunit of laminin-211 (= merosin) and result in either partial or complete laminin-211 deficiency. Complete merosin deficiency is ...typically associated with a more severe congenital muscular dystrophy, clinically manifested by hypotonia and weakness at birth, the development of contractures of large joints and progressive respiratory involvement. Muscle atrophy and severe weakness typically prevent independent ambulation. Partial merosin deficiency is mostly manifested by later onset limb-girdle weakness and joint contractures so that independent ambulation is typically achieved. Collectively, complete and partial merosin deficiency are referred to as LAMA2-related dystrophies (LAMA2-RDs) and represent one of most common forms of congenital muscular dystrophies worldwide. LAMA2-RDs are classically characterized by both central and peripheral nervous system involvement with abnormal appearing white matter on brain MRI and dystrophic appearing muscle on muscle biopsy as well as creatine kinase levels commonly elevated to > 1,000 IU/L. Next generation sequencing has greatly improved diagnostic abilities for LAMA2-RD, and the majority of patients with merosin deficiency carry recessive pathogenic variants in the LAMA2 gene. The existence of multiple animal models for LAMA2-RDs has helped to advance our understanding of laminin-211 and has been instrumental in preclinical research progress and translation to clinical trials. The first clinical trial for the LAMA2-RDs was a phase 1 pharmacokinetic and safety study of the anti-apoptotic compound omigapil, based on preclinical studies performed in the dyW/dyW and dy2J/dy2Jmouse models. This phase 1 study enabled the collection of pulmonary and motor outcome measures and also provided the opportunity for investigating exploratory outcome measures including muscle ultrasound, muscle MRI and serum and urine biomarker collection. Natural history studies, including a five-year prospective natural history and comparative outcome measures study in patients with LAMA2-RD, have helped to better delineate the natural history and identify viable outcome measures. Plans for further clinical trials for LAMA2-RDs are presently in progress, highlighting the necessity of identifying adequate, disease-relevant biomarkers, capable of reflecting potential therapeutic changes, in addition to refining the clinical outcome measures and time-to-event trajectory analysis of affected patients
Graphitic carbon nitride (g-CN) has interesting catalytic properties but is difficult to study due to its structure and how it is produced. In this study, linear
-heptazine oligomers were synthesized ...to serve as well-defined molecular models for g-CN. Cyclic voltammetry, absorption and emission spectroscopies showed a clear shift of properties towards those of g-CN as the number of heptazine units increased. DFT calculations supported the characterizations, and helped refine the properties observed.
Background Atrial fibrillation (AF) is common, often without symptoms, and is an independent risk factor for mortality, stroke and heart failure. It is unknown if screening asymptomatic individuals ...for AF can improve clinical outcomes. Methods mSToPS was a pragmatic, direct-to-participant trial that randomized individuals from a single US-wide health plan to either immediate or delayed screening using a continuous-recording ECG patch to be worn for two weeks and 2 occasions, ~3 months apart, to potentially detect undiagnosed AF. The 3-year outcomes component of the trial was designed to compare clinical outcomes in the combined cohort of 1718 individuals who underwent monitoring and 3371 matched observational controls. The prespecified primary outcome was the time to first event of the combined endpoint of death, stroke, systemic embolism, or myocardial infarction among individuals with a new AF diagnosis, which was hypothesized to be the same in the two cohorts but was not realized. Results Over the 3 years following the initiation of screening (mean follow-up 29 months), AF was newly diagnosed in 11.4% (n = 196) of screened participants versus 7.7% (n = 261) of observational controls (p<0.01). Among the screened cohort with incident AF, one-third were diagnosed through screening. For all individuals whose AF was first diagnosed clinically, a clinical event was common in the 4 weeks surrounding that diagnosis: 6.6% experienced a stroke,10.2% were newly diagnosed with heart failure, 9.2% had a myocardial infarction, and 1.5% systemic emboli. Cumulatively, 42.9% were hospitalized. For those diagnosed via screening, none experienced a stroke, myocardial infarction or systemic emboli in the period surrounding their AF diagnosis, and only 1 person (2.3%) had a new diagnosis of heart failure. Incidence rate of the prespecified combined primary endpoint was 3.6 per 100 person-years among the actively monitored cohort and 4.5 per 100 person-years in the observational controls. Conclusions At 3 years, screening for AF was associated with a lower rate of clinical events and improved outcomes relative to a matched cohort, although the influence of earlier diagnosis of AF via screening on this finding is unclear. These observational data, including the high event rate surrounding a new clinical diagnosis of AF, support the need for randomized trials to determine whether screening for AF will yield a meaningful protection from strokes and other clinical events. Trail registration The mHealth Screening To Prevent Strokes (mSToPS) Trial is registered on ClinicalTrials.gov with the identifier NCT02506244.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Summary Background Intervention to achieve alcohol abstinence represents the most effective treatment for alcohol-dependent patients with liver cirrhosis; however, anticraving drugs might worsen ...liver disease. We aimed to investigate the effectiveness and safety of baclofen in achieving and maintaining alcohol abstinence in patients with liver cirrhosis. Methods Between October, 2003, and November, 2006, 148 alcohol-dependent patients with liver cirrhosis were referred to the Institute of Internal Medicine, Rome, Italy. 84 were randomly allocated either oral baclofen or placebo for 12 weeks. Primary outcome was proportion of patients achieving and maintaining alcohol abstinence. Measures of this outcome were total alcohol abstinence and cumulative abstinence duration, which were assessed at outpatient visits. Relapse was defined as alcohol intake of more than four drinks per day or overall consumption of 14 or more drinks per week over a period of at least 4 weeks. Analysis was by intention to treat. This study is registered with ClinicalTrials.gov , number NCT00525252. Findings Of 42 patients allocated baclofen, 30 (71%) achieved and maintained abstinence compared with 12 (29%) of 42 assigned placebo (odds ratio 6·3 95% CI 2·4–16·1; p=0·0001). The number of dropouts (termination of treatment) did not differ between the baclofen (6/42 14%) and placebo (13/42 31%) groups (p=0·12). Cumulative abstinence duration was about twofold higher in patients allocated baclofen than in those assigned placebo (mean 62·8 SE 5·4 vs 30·8 5·5 days; p=0·001). No hepatic side-effects were recorded. Interpretation Baclofen is effective at promoting alcohol abstinence in alcohol-dependent patients with liver cirrhosis. The drug is well tolerated and could have an important role in treatment of these individuals.
Many hypertensive subjects travel to high altitudes, but little is known on ambulatory blood pressure (ABP) changes and antihypertensive drugs' efficacy under acute and prolonged exposure to ...hypobaric hypoxia. In particular, the efficacy of angiotensin receptor blockers in this condition is unknown. This may be clinically relevant considering that renin-angiotensin system activity changes at altitude. The HIGHCARE-HIMALAYA study assessed changes in 24 h ABP under acute and prolonged exposure to increasing altitude and blood pressure-lowering efficacy and safety of an angiotensin receptor blockade in this setting.
Forty-seven healthy, normotensive lowlanders were randomized to telmisartan 80 mg or placebo in a double-blind, parallel group trial. Conventional and Ambulatory BPs were measured at baseline and on treatment: after 8 weeks at sea level, and under acute exposure to 3400 and 5400 m altitude, the latter upon arrival and after 12 days (Mt. Everest base camp). Blood samples were collected for plasma catecholamines, renin, angiotensin, and aldosterone. In both groups, exposure to increasing altitude was associated with: (i) significant progressive increases in conventional and 24 h blood pressure, persisting throughout the exposure to 5400 m; (ii) increased plasma noradrenaline and suppressed renin-angiotensin-aldosterone system. Telmisartan lowered 24 h ABP at the sea level and at 3400 m (between-group difference 4.0 mmHg, 95% CI: 2.2-9.5 mmHg), but not at 5400 m.
Ambulatory blood pressure increases progressively with increasing altitude, remaining elevated after 3 weeks. An angiotensin receptor blockade maintains blood pressure-lowering efficacy at 3400 m but not at 5400 m.
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