SciCombinator

Discover the most talked about and latest scientific content & concepts.

Journal: EBioMedicine

52

The emergence and prevalence of antibiotic-resistant bacteria are an increasing cause of death worldwide, resulting in a global ‘call to action’ to avoid receding into an era lacking effective antibiotics. Despite the urgency, the healthcare industry still relies on a single in vitro bioassay to determine antibiotic efficacy. This assay fails to incorporate environmental factors normally present during host-pathogen interactions in vivo that significantly impact antibiotic efficacy. Here we report that standard antimicrobial susceptibility testing (AST) failed to detect antibiotics that are in fact effective in vivo; and frequently identified antibiotics that were instead ineffective as further confirmed in mouse models of infection and sepsis. Notably, AST performed in media mimicking host environments succeeded in identifying specific antibiotics that were effective in bacterial clearance and host survival, even though these same antibiotics failed in results using standard test media. Similarly, our revised media further identified antibiotics that were ineffective in vivo despite passing the AST standard for clinical use. Supplementation of AST medium with sodium bicarbonate, an abundant in vivo molecule that stimulates global changes in bacterial structure and gene expression, was found to be an important factor improving the predictive value of AST in the assignment of appropriate therapy. These findings have the potential to improve the means by which antibiotics are developed, tested, and prescribed.

Concepts: Gene, Gene expression, Bacteria, Evolution, Antibiotic resistance, Microorganism, Penicillin, Clostridium difficile

50

Iron deficiency causes long-term adverse consequences for children and is the most common nutritional deficiency worldwide. Observational studies suggest that iron deficiency anemia protects against Plasmodiumfalciparum malaria and several intervention trials have indicated that iron supplementation increases malaria risk through unknown mechanism(s). This poses a major challenge for health policy. We investigated how anemia inhibits blood stage malaria infection and how iron supplementation abrogates this protection.

Concepts: Immune system, Hemoglobin, Malaria, Plasmodium falciparum, Red blood cell, Iron deficiency anemia, Sickle-cell disease, Transferrin

46

We aimed to determine whether the levels of total serum IgM and IgG, together with specific antibodies against malondialdehyde-conjugated low-density lipoprotein (MDA-LDL), can improve cardiovascular risk discrimination.

Concepts: Immune system, Glycoproteins, Blood, Myocardial infarction, Atherosclerosis, Cardiovascular disease, Immunology, Antibodies

45

Dupuytren’s disease is a common fibrotic condition of the hand that causes irreversible flexion contractures of the fingers, with no approved therapy for early stage disease. Our previous analysis of surgically-excised tissue defined tumour necrosis factor (TNF) as a potential therapeutic target. Here we assessed the efficacy of injecting nodules of Dupuytren’s disease with a TNF inhibitor.

42

Molecular assays have not yet been able to replace time-consuming culture-based methods in clinical mycobacteriology. Using 6875 clinical samples and a study period of 35months we evaluated the use of PCR-based assays to establish a diagnostic workflow with a fast time-to-result of 1-2days, for 1. detection of Mycobacterium tuberculosis complex (MTB), 2. detection and identification of nontuberculous mycobacteria (NTM), and 3. identification of drug susceptible MTB. MTB molecular-based detection and culture gave concordant results for 97.7% of the specimens. NTM PCR-based detection and culture gave concordant results for 97.0% of the specimens. Defining specimens on the basis of combined laboratory data as true positives or negatives with discrepant results resolved by clinical chart reviews, we calculated sensitivity, specificity, PPV and NPV for PCR-based MTB detection as 84.7%, 100%, 100%, and 98.7%; the corresponding values for culture-based MTB detection were 86.3%, 100%, 100%, and 98.8%. PCR-based detection of NTM had a sensitivity of 84.7% compared to 78.0% of that of culture-based NTM detection. Molecular drug susceptibility testing (DST) by line-probe assay was found to predict phenotypic DST results in MTB with excellent accuracy. Our findings suggest a diagnostic algorithm to largely replace lengthy culture-based techniques by rapid molecular-based methods.

Concepts: Type I and type II errors, Sensitivity and specificity, Tuberculosis, Assay, Mycobacterium, Mycobacterium tuberculosis, Mycobacterium avium complex, Nontuberculous mycobacteria

40

Acetaminophen (paracetamol) is one of the most common medications used for management of pain in the world. There is lack of consensus about the mechanism of action, and concern about the possibility of adverse effects on reproductive health.

Concepts: Health, Influenza, Cytochrome P450, Paracetamol, Adverse drug reaction, World, Adverse effect

36

The nascent field of ‘Nutritional Psychiatry’ offers much promise for addressing the large disease burden associated with mental disorders. A consistent evidence base from the observational literature confirms that the quality of individuals' diets is related to their risk for common mental disorders, such as depression. This is the case across countries and age groups. Moreover, new intervention studies implementing dietary changes suggest promise for the prevention and treatment of depression. Concurrently, data point to the utility of selected nutraceuticals as adjunctive treatments for mental disorders and as monotherapies for conditions such as ADHD. Finally, new studies focused on understanding the biological pathways that mediate the observed relationships between diet, nutrition and mental health are pointing to the immune system, oxidative biology, brain plasticity and the microbiome-gut-brain axis as key targets for nutritional interventions. On the other hand, the field is currently limited by a lack of data and methodological issues such as heterogeneity, residual confounding, measurement error, and challenges in measuring and ensuring dietary adherence in intervention studies. Key challenges for the field are to now: replicate, refine and scale up promising clinical and population level dietary strategies; identify a clear set of biological pathways and targets that mediate the identified associations; conduct scientifically rigorous nutraceutical and ‘psychobiotic’ interventions that also examine predictors of treatment response; conduct observational and experimental studies in psychosis focused on dietary and related risk factors and treatments; and continue to advocate for policy change to improve the food environment at the population level.

Concepts: Immune system, Scientific method, Nutrition, Measurement, Mental health, Mental disorder, Psychiatry, Nutraceutical

33

Circadian rhythms are fundamental to health and are particularly important for mental wellbeing. Disrupted rhythms of rest and activity are recognised as risk factors for major depressive disorder and bipolar disorder.

30

The quality of clinical biobank samples is crucial to their value for life sciences research. A number of factors related to the collection and storage of samples may affect the biomolecular composition. We have studied the effect of long-time freezer storage, chronological age at sampling, season and month of the year and on the abundance levels of 108 proteins in 380 plasma samples collected from 106 Swedish women. Storage time affected 18 proteins and explained 4.8-34.9% of the observed variance. Chronological age at sample collection after adjustment for storage-time affected 70 proteins and explained 1.1-33.5% of the variance. Seasonal variation had an effect on 15 proteins and month (number of sun hours) affected 36 proteins and explained up to 4.5% of the variance after adjustment for storage-time and age. The results show that freezer storage time and collection date (month and season) exerted similar effect sizes as age on the protein abundance levels. This implies that information on the sample handling history, in particular storage time, should be regarded as equally prominent covariates as age or gender and need to be included in epidemiological studies involving protein levels.

Concepts: Oxygen, Epidemiology, Molecular biology, Sample size, Effect, Affect, Season, C-reactive protein

28

The neurotransmitter γ-aminobutyric acid (GABA) is an extracellular signaling molecule in the brain and in pancreatic islets. Here, we demonstrate that GABA regulates cytokine secretion from human peripheral blood mononuclear cells (PBMCs) and CD4+T cells. In anti-CD3 stimulated PBMCs, GABA (100nM) inhibited release of 47 cytokines in cells from patients with type 1 diabetes (T1D), but only 16 cytokines in cells from nondiabetic (ND) individuals. CD4+T cells from ND individuals were grouped into responder or non-responder T cells according to effects of GABA (100nM, 500nM) on the cell proliferation. In the responder T cells, GABA decreased proliferation, and inhibited secretion of 37 cytokines in a concentration-dependent manner. In the non-responder T cells, GABA modulated release of 8 cytokines. GABA concentrations in plasma from T1D patients and ND individuals were correlated with 10 cytokines where 7 were increased in plasma of T1D patients. GABA inhibited secretion of 5 of these cytokines from both T1D PBMCs and ND responder T cells. The results identify GABA as a potent regulator of both Th1- and Th2-type cytokine secretion from human PBMCs and CD4+T cells where GABA generally decreases the secretion.

Concepts: Immune system, Cytokine, Signal transduction, Insulin, Diabetes mellitus, Cell biology, Diabetes mellitus type 1, PBMC