Substrate specificity of human chymotrypsin-like protease (CTRL) characterized by phage display-selected small-protein inhibitors

Chymotrypsin-like protease (CTRL) is one of the four chymotrypsin isoforms expressed in the human exocrine pancreas. Human genetic and experimental evidence indicate that chymotrypsins B1, B2, and C (CTRB1, CTRB2 and CTRC) are important not only for protein digestion but also for protecting the pancreas against pancreatitis by degrading potentially harmful trypsinogen. CTRL has not been reported to play a similar role, possibly due to its low abundance and/or different substrate specificity. To address this problem, we investigated the specificity of the substrate-binding groove of CTRL by evolving the substrate-like canonical loop of the Schistocerca gregaria proteinase inhibitor 2 (SGPI-2), a small-protein reversible chymotrypsin inhibitor to bind CTRL. We found that phage-associated SGPI-2 variants with strong affinity to CTRL were similar to those evolved previously against CTRB1, CTRB2 or bovine chymotrypsin A (bCTRA), indicating comparable substrate specificity. When tested as recombinant proteins, SGPI-2 variants inhibited CTRL with similar or slightly weaker affinity than bCTRA, confirming that CTRL is a typical chymotrypsin. Interestingly, an SGPI-2 variant selected with a Thr29His mutation in its reactive loop was found to inhibit CTRL strongly, but it was digested rapidly by bCTRA. Finally, CTRL was shown to degrade human anionic trypsinogen, however, at a much slower rate than CTRB2, suggesting that CTRL may not have a significant role in the pancreatic defense mechanisms against inappropriate trypsinogen activation and pancreatitis.     

Diet composition,nutrient substitutions and circulating fatty acids in relation to ectopic and visceral fat depots

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Ultra-processed foods: Cross-sectional and longitudinal association with uric acid and hyperuricemia in ELSA-Brasil

Background and aimsFood intake influences uric acid (UA) levels and hyperuricemia (HU), but evidence on the role of ultra-processed foods (UPFs) are scarce. The association between UPFs consumption and (1) HU prevalence and UA levels; (2) HU cumulative incidence; and (3) UA level change over a 4-year period was investigated.Methods and resultsCross-sectional and longitudinal analyses were performed using baseline (2008–2010, aged 35–74 years) and second visit (2012–2014) data from the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). Participants with glomerular filtration rate <60 mL/min/1.73 m2, bariatric surgery, implausible caloric intake, and using urate-lowering therapy (ULT) at baseline were excluded (all analyses). Participants with HU at baseline were excluded from longitudinal analyses. UPFs consumption was assessed using a food frequency questionnaire (FFQ) and categorized by the NOVA classification system (100 g/day). HU was defined as UA≥6.8 mg/dL. Linear, logistic, and mixed-effect linear regressions investigated the associations between UPFs consumption and UA/HU, adjusted for covariates. The final samples included 13,923 (cross-sectional) and 10,517 (longitudinal) individuals. The prevalence of HU was 18.7%, and the cumulative incidence was 4.9%. Greater UPFs consumption was associated with a greater prevalence of HU (OR:1.025 95%CI: 1.006; 1.044) and higher UA levels (β:0.024 95%CI: 0.016; 0.032). Every additional consumption of 100 g/day of UPFs raised the 4-year cumulative incidence of HU by 5.6% (95%CI: 1.021; 1.092). However, UPFs were not associated with the pace of UA level changes during the study period.ConclusionThe present study shows that greater UPFs consumption is associated with another deleterious health consequence: higher UA levels and the risk of having HU.     

Associations of influenza and pneumococcal vaccinations with burdens of older family caregivers: The Japan Gerontological Evaluation study (JAGES) cross-sectional study

BackgroundInfluenza and pneumonia tend to be severe in older adults; thus, vaccination is necessary to prevent these illnesses. Vaccination is especially important for older family caregivers (OFCs) not only to prevent them from becoming ill, but also to prevent secondary infections in the family care receivers (FCRs), who are mostly frail older adults and have a higher risk of severe illness. Thus, we investigated whether caregiving burdens were associated with the vaccinations among older adults.MethodsWe used cross-sectional data from the Japan Gerontological Evaluation Study (JAGES), which was conducted in 64 Japanese municipalities from November 2019 to January 2020. The target population consisted of 26,177 individuals aged 65 years or older who were independent and did not need public long-term care. The primary outcome was the uptakes of either or both influenza and pneumococcal vaccinations. Multinomial logistic regressions were performed, setting those who underwent neither vaccinations as the reference group.ResultsAmong the participants, 23.3 %, 25.8 %, 9.4 %, or 41.5 % underwent neither, only influenza, only pneumococcal, or the both vaccinations, respectively. The caregiving frequency, time length in a day, or dementia of FCR were negatively associated with influenza vaccination (caregiving almost every day: relative risk ratio {RRR}: 0.39, 95 % confident interval {95 % CI} [0.24–0.63]; caregiving almost all day: 0.44, 95 % CI: 0.23–0.85; caregiving for FCR: RRR:0.55, 95 % CI: 0.34–0.91). On the other hand, those caregiving burdens were not associated with pneumococcal only or the both vaccinations. Having a family physician mitigated all the negative effect of the caregiving burdens on the vaccinations.ConclusionOur results suggest that the caregiving burden is a barrier to influenza vaccination but not to pneumococcal vaccination and that having a physician mitigates the negative effect regardless of the burden kind.     

测量偏倚的方向性：基于有向无环图的结构解析

测量偏倚(MB)的因果结构已有阐述但仍不完全明确;实践上, 暴露与结局间效应的替代估计值(SE)的正确性是因果推断的前提, 通常基于测量的暴露与测量的结局间双向无差别的错分。本文提出了基于有向无环图(DAG)的单个变量测量的结构, 其MB来源于对不完美的、类似"输入/输出设备"的测量系统的选择。SE的MB受到测量系统本身和测量系统外因素的双重影响:虽然测量系统的独立性或依赖性机制仍可确保SE的MB表现为双向无差别的错分, 然而测量系统外因素对SE的MB则可表现为双向无差别、单向或双向有差别的错分。此外, 反向因果关系是定义在测量水平上, 测量的暴露可以影响测量的结局, 反之亦然。结合时序关系, DAGs有助于阐明MB的结构、机制和方向性。     

Inflammation-mediated tissue damage in pulmonary tuberculosis and host-directed therapeutic strategies

Treatment of tuberculosis (TB) involves the administration of anti-mycobacterial drugs for several months. The emergence of drug-resistant strains of Mycobacterium tuberculosis (Mtb, the causative agent) together with increased disease severity in people with co-morbidities such as diabetes mellitus and HIV have hampered efforts to reduce case fatality. In severe disease, TB pathology is largely attributable to over-exuberant host immune responses targeted at controlling bacterial replication. Non-resolving inflammation driven by host pro-inflammatory mediators in response to high bacterial load leads to pulmonary pathology including cavitation and fibrosis. The need to improve clinical outcomes and reduce treatment times has led to a two-pronged approach involving the development of novel antimicrobials as well as host-directed therapies (HDT) that favourably modulate immune responses to Mtb. HDT strategies incorporate aspects of immune modulation aimed at downregulating non-productive inflammatory responses and augmenting antimicrobial effector mechanisms to minimise pulmonary pathology and accelerate symptom resolution. HDT in combination with existing antimycobacterial agents offers a potentially promising strategy to improve the long-term outcome for TB patients. In this review, we describe components of the host immune response that contribute to inflammation and tissue damage in pulmonary TB, including cytokines, matrix metalloproteinases, lipid mediators, and neutrophil extracellular traps. We then proceed to review HDT directed at these pathways.     

Bayesian graphical modeling for heterogeneous causal effects

There is a growing interest in current medical research to develop personalized treatments using a molecular-based approach. The broad goal is to implement a more precise and targeted decision-making process, relative to traditional treatments based primarily on clinical diagnoses. Specifically, we consider patients affected by Acute Myeloid Leukemia (AML), an hematological cancer characterized by uncontrolled proliferation of hematopoietic stem cells in the bone marrow. Because AML responds poorly to chemotherapeutic treatments, the development of targeted therapies is essential to improve patients' prospects. In particular, the dataset we analyze contains the levels of proteins involved in cell cycle regulation and linked to the progression of the disease. We evaluate treatment effects within a causal framework represented by a Directed Acyclic Graph (DAG) model, whose vertices are the protein levels in the network. A major obstacle in implementing the above program is represented by individual heterogeneity. We address this issue through a Dirichlet Process (DP) mixture of Gaussian DAG-models where both the graphical structure as well as the allied model parameters are regarded as uncertain. Our procedure determines a clustering structure of the units reflecting the underlying heterogeneity, and produces subject-specific estimates of causal effects based on Bayesian Model Averaging (BMA). With reference to the AML dataset, we identify different effects of protein regulation among individuals; moreover, our method clusters patients into groups that exhibit only mild similarities with traditional categories based on morphological features.     

Dependence between cognitive impairment and metabolic syndrome applied to a Brazilian elderly dataset

Globally, the proportion of elderly individuals in the population has increased substantially in the last few decades. However, the risk factors that should be managed in advance to ensure a natural process of mental decline due to aging remain unknown. In this study, a dataset consisting of a Brazilian elderly sample was modelled using a Bayesian Network (BN) approach to uncover connections between cognitive performance measures and potential influence factors. Regarding its structure (a Directed Acyclic Graph), it was investigated the probabilistic dependence mechanism between two variables of medical interest: the suspected risk factor known as Metabolic Syndrome (MetS) and the indicator of mental decline referred to as Cognitive Impairment (CI). In this investigation, the concept known in the context of a BN as D-separation has been employed. Results of the conducted study revealed that the dependence between MetS and Cognitive Variables (CI and its direct determinants) in fact exists and depends on both Body Mass Index (BMI) and age.