Substrate Flexibility of a Mutated Acyltransferase Domain and Implications for Polyketide Biosynthesis

SummaryPolyketides are natural products frequently used for the treatment of various diseases, but their structural complexity hinders efficient derivatization. In this context, we recently introduced enzyme-directed mutasynthesis to incorporate non-native extender units into the biosynthesis of erythromycin. Modeling and mutagenesis studies led to the discovery of a variant of an acyltransferase domain in the erythromycin polyketide synthase capable of accepting a propargylated substrate. Here, we extend molecular rationalization of enzyme-substrate interactions through modeling, to investigate the incorporation of substrates with different degrees of saturation of the malonic acid side chain. This allowed the engineered biosynthesis of new erythromycin derivatives and the introduction of additional mutations into the AT domain for a further shift of the enzyme's substrate scope. Our approach yields non-native polyketide structures with functional groups that will simplify future derivatization approaches, and provides a blueprint for the engineering of AT domains to achieve efficient polyketide synthase diversification

Research training needs in Peruvian national TB/HIV programs

<p>Abstract</p> <p>Background</p> <p>There are few published reports of <it>research training </it>needs assessments and research training programs. In an effort to expand this nascent field of study and to bridge the gap between research and practice, we sought to systematically assess the research training needs of health care professionals working at Peruvian governmental institutions leading HIV and tuberculosis (TB) control and among senior stakeholders in the field.</p> <p>Methods</p> <p>Six institutional workshops were conducted with the participation of 161 mid-level health professionals from agencies involved in national HIV and TB control. At each workshop informants completed a structured questionnaire and participated in small and large group discussions. Additional data and institutional commitment was obtained through in-depth interviews from 32 senior managers and researchers from the Ministry of Health, academia and NGOs.</p> <p>Results</p> <p>Participants exhibited an overwhelming receptivity for additional research training, observing a gap between current levels of research training and their perceived importance. Specialized skills in obtaining funding, developing research protocols, particularly in operational, behavioral and prevention research were considered in greatest need. Beyond research training, participants identified broader social, economic and political factors as influential in infectious disease control.</p> <p>Conclusions</p> <p>The needs assessment suggests that future training should focus on operational research techniques, rather than on clinical skill building or program implementation only. Strengthening health systems not only requires additional research training, but also adequate financial resources to implement research findings.</p

Estado inmunonutricional en niños con diarrea crónica inespecífica

Introducción : la ruptura del equilibrio inmunonutricional en los pacientes con diarrea crónica inespecífica (DCI) entorpece la evolución clínica y favorece la aparición de complicaciones. Objetivo: caracterizar el estado inmunonutricional de niños con Diarrea Crónica Inespecífica. Materiales y Método: se realizó un estudio descriptivo transversal a 44 niños menores de 6 años con diagnóstico de diarrea crónica inespecífica, atendidos en el Instituto de Gastroenterología en el período comprendido de marzo del 2012 a mayo 2014. A todos se les aplicó cuestionario, previo consentimiento informado y se les realizó mensuraciones antropométricas, exámenes parasitológicos y bacteriológicos en heces, hemograma completo, determinación de hierro sérico, dosificación de inmunoglobulinas totales y ultrasonido de timo. Para el análisis estadístico se emplearon distribuciones de frecuencia y para la comparación entre los grupos se utilizó la prueba del X2. Se consideró significativo una p &lt; 0,05. Resultados: la población objeto de estudio no superó los 4 años de edad, con un predominio del sexo masculino sin asociación entre edad y sexo. El 43.2% de los pacientes presentó algún grado de malnutrición con un comportamiento similar entre los malnutridos por defecto y por exceso. Poco menos de la mitad de los pacientes tuvo anemia. La hipoplasia tímica y los niveles séricos bajos de IgA fueron condiciones frecuentes en la población estudiada. Conclusiones: el compromiso del estado inmunonutricional de los niños con diarrea crónica inespecífica no es infrecuente. Se manifiesta en elevada frecuencia de malnutrición, anemia, hipoplasia tímica y niveles séricos bajos de IgA. Palabras clave: Diarrea crónica inespecífica, equilibrio inmunonutricional hipoplasia tímica. ABSTRACT  Introduction: breaking down the immune nutritional balance in patients with chronic nonspecific diarrhea (ICD) hinders the clinical course and promotes complications. Objective: to characterize the immune nutritional state of children with ICD. Material and Methods: a cross-sectional study in 44 children younger than 6 years prior consent was performed with a diagnosis of chronic nonspecific diarrhea treated at the Institute of Gastroenterology from March 2012 to May 2014. Aconsent informed questionnaire was applied previously to all patients, who underwent anthropometric assessment, bacteriological and parasitological stool examinations, complete blood count, determination of serum iron, determination of total immunoglobulin and ultrasound thymus. Statistical analysis included, frequency distributions, to comparison among the test groups, Chi-square test was done (considering significant; p&lt;0.05). Results: the population did not exceed 4 years old, with a male predominance and no association between age and sex. 43.2% of patients had some grade of malnutrition without differences between calorie and protein malnutrition and overweight. Just under half of the patients had anemia. Thymic hypoplasia and low serum IgA levels were more common conditions. Conclusions: the commitment of immune nutritional status of children with chronic nonspecific diarrhea is not uncommon. It manifests itself in high frequency of malnutrition, anemia, thymic hypoplasia, and low serum IgA.  Keywords: Chronic nonspecific diarrhea, immune nutritional state, thymic hypoplasia.</p

Hexokinase 2 as a novel selective metabolic target for rheumatoid arthritis

Objectives: Recent studies indicate that glucose metabolism is altered in rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLS). Hexokinases (HKs) catalyse the first step in glucose metabolism, and HK2 constitutes the principal HK inducible isoform. We hypothesise that HK2 contributes to the synovial lining hypertrophy and plays a critical role in bone and cartilage damage. Methods: HK1 and HK2 expression were determined in RA and osteoarthritis (OA) synovial tissue by immunohistochemistry. RA FLS were transfected with either HK1 or HK2 siRNA, or infected with either adenovirus (ad)-GFP, ad-HK1 or ad-HK2. FLS migration and invasion were assessed. To study the role of HK2 in vivo, 108 particles of ad-HK2 or ad-GFP were injected into the knee of wild-type mice. K/BxN serum transfer arthritis was induced in HK2F/F mice harbouring Col1a1-Cre (HK2Col1), to delete HK2 in non-haematopoietic cells. Results: HK2 is particular of RA histopathology (9/9 RA; 1/8 OA) and colocalises with FLS markers. Silencing HK2 in RA FLS resulted in a less invasive and migratory phenotype. Consistently, overexpression of HK2 resulted in an increased ability to migrate and invade. It also increased extracellular lactate production. Intra-articular injection of ad-HK2 in normal knees dramatically increased synovial lining thickness, FLS activation and proliferation. HK2 was highly expressed in the synovial lining after K/BxN serum transfer arthritis. HK2Col1 mice significantly showed decreased arthritis severity, bone and cartilage damage. Conclusion: HK2 is specifically expressed in RA synovial lining and regulates FLS aggressive functions. HK2 might be an attractive selective metabolic target safer than global glycolysis for RA treatment

Planeación, gobernanza y sustentabilidad Retos y desafíos desde el enfoque territorial

Frente a la compleja realidad actual, resulta ineludible el desarrollo de la investigación científica de los fenómenos y procesos urbanos, territoriales y ambientales, que contribuya a su comprensión y la construcción de alternativas de solución a los retos y desafíos vigentes. En este contexto, el abordaje de las ciudades y regiones metropolitanas, el ordenamiento del territorio y la ocupación del espacio, así como la relación sociedad-naturaleza y la complejidad ambiental, precisa la generación de metodologías y procesos de investigación multi e inter disciplinarios que contribuyan a la comprensión de los procesos socioterritoriales, el mejoramiento de las condiciones de vida y la conservación ambiental.Programa de Fortalecimiento de la Calidad Educativa PFCE-2016 proyecto K0313101

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

PREDICT identifies precipitating events associated with the clinical course of acutely decompensated cirrhosis

Background & Aims: Acute decompensation (AD) of cirrhosis may present without acute-on-chronic liver failure (ACLF) (ADNo ACLF), or with ACLF (AD-ACLF), defined by organ failure(s). Herein, we aimed to analyze and characterize the precipitants leading to both of these AD phenotypes. Methods: The multicenter, prospective, observational PREDICT study (NCT03056612) included 1,273 non-electively hospitalized patients with AD (No ACLF = 1,071; ACLF = 202). Medical history, clinical data and laboratory data were collected at enrolment and during 90-day follow-up, with particular attention given to the following characteristics of precipitants: induction of organ dysfunction or failure, systemic inflammation, chronology, intensity, and relationship to outcome. Results: Among various clinical events, 4 distinct events were precipitants consistently related to AD: proven bacterial infections, severe alcoholic hepatitis, gastrointestinal bleeding with shock and toxic encephalopathy. Among patients with precipitants in the AD-No ACLF cohort and the AD-ACLF cohort (38% and 71%, respectively), almost all (96% and 97%, respectively) showed proven bacterial infection and severe alcoholic hepatitis, either alone or in combination with other events. Survival was similar in patients with proven bacterial infections or severe alcoholic hepatitis in both AD phenotypes. The number of precipitants was associated with significantly increased 90day mortality and was paralleled by increasing levels of surrogates for systemic inflammation. Importantly, adequate first-line antibiotic treatment of proven bacterial infections was associated with a lower ACLF development rate and lower 90-day mortality. Conclusions: This study identified precipitants that are significantly associated with a distinct clinical course and prognosis in patients with AD. Specific preventive and therapeutic strategies targeting these events may improve outcomes in patients with decompensated cirrhosis. Lay summary: Acute decompensation (AD) of cirrhosis is characterized by a rapid deterioration in patient health. Herein, we aimed to analyze the precipitating events that cause AD in patients with cirrhosis. Proven bacterial infections and severe alcoholic hepatitis, either alone or in combination, accounted for almost all (96-97%) cases of AD and acute-on-chronic liver failure. Whilst the type of precipitant was not associated with mortality, the number of precipitant(s) was. This study identified precipitants that are significantly associated with a distinct clinical course and prognosis of patients with AD. Specific preventive and therapeutic strategies targeting these events may improve patient outcomes. (c) 2020 European Association for the Study of the Liver. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

The PREDICT study uncovers three clinical courses of acutely decompensated cirrhosis that have distinct pathophysiology

Acute decompensation (AD) of cirrhosis is defined as the acute development of ascites, gastrointestinal hemorrhage, hepatic encephalopathy, infection or any combination thereof, requiring hospitalization. The presence of organ failure(s) in patients with AD defines acute-on-chronic liver failure (ACLF). The PREDICT study is a European, prospective, observational study, designed to characterize the clinical course of AD and to identify predictors of ACLF. A total of 1,071 patients with AD were enrolled. We collected detailed pre-specified information on the 3-month period prior to enrollment, and clinical and laboratory data at enrollment. Patients were then closely followed up for 3 months. Outcomes (liver transplantation and death) at 1 year were also recorded. Three groups of patients were identified. Pre-ACLF patients (n = 218) developed ACLF and had 3-month and 1-year mortality rates of 53.7% and 67.4%, respectively. Unstable decompensated cirrhosis (UDC) patients (n = 233) required ≥1 readmission but did not develop ACLF and had mortality rates of 21.0% and 35.6%, respectively. Stable decompensated cirrhosis (SDC) patients (n = 620) were not readmitted, did not develop ACLF and had a 1-year mortality rate of only 9.5%. The 3 groups differed significantly regarding the grade and course of systemic inflammation (high-grade at enrollment with aggravation during follow-up in pre-ACLF; low-grade at enrollment with subsequent steady-course in UDC; and low-grade at enrollment with subsequent improvement in SDC) and the prevalence of surrogates of severe portal hypertension throughout the study (high in UDC vs. low in pre-ACLF and SDC). Acute decompensation without ACLF is a heterogeneous condition with 3 different clinical courses and 2 major pathophysiological mechanisms: systemic inflammation and portal hypertension. Predicting the development of ACLF remains a major future challenge. ClinicalTrials.gov number: NCT03056612. Lay summary: Herein, we describe, for the first time, 3 different clinical courses of acute decompensation (AD) of cirrhosis after hospital admission. The first clinical course includes patients who develop acute-on-chronic liver failure (ACLF) and have a high short-term risk of death - termed pre-ACLF. The second clinical course (unstable decompensated cirrhosis) includes patients requiring frequent hospitalizations unrelated to ACLF and is associated with a lower mortality risk than pre-ACLF. Finally, the third clinical course (stable decompensated cirrhosis), includes two-thirds of all patients admitted to hospital with AD - patients in this group rarely require hospital admission and have a much lower 1-year mortality risk

Cabbage and fermented vegetables : From death rate heterogeneity in countries to candidates for mitigation strategies of severe COVID-19

Large differences in COVID-19 death rates exist between countries and between regions of the same country. Some very low death rate countries such as Eastern Asia, Central Europe, or the Balkans have a common feature of eating large quantities of fermented foods. Although biases exist when examining ecological studies, fermented vegetables or cabbage have been associated with low death rates in European countries. SARS-CoV-2 binds to its receptor, the angiotensin-converting enzyme 2 (ACE2). As a result of SARS-CoV-2 binding, ACE2 downregulation enhances the angiotensin II receptor type 1 (AT(1)R) axis associated with oxidative stress. This leads to insulin resistance as well as lung and endothelial damage, two severe outcomes of COVID-19. The nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is the most potent antioxidant in humans and can block in particular the AT(1)R axis. Cabbage contains precursors of sulforaphane, the most active natural activator of Nrf2. Fermented vegetables contain many lactobacilli, which are also potent Nrf2 activators. Three examples are: kimchi in Korea, westernized foods, and the slum paradox. It is proposed that fermented cabbage is a proof-of-concept of dietary manipulations that may enhance Nrf2-associated antioxidant effects, helpful in mitigating COVID-19 severity.Peer reviewe

Nrf2-interacting nutrients and COVID-19 : time for research to develop adaptation strategies

There are large between- and within-country variations in COVID-19 death rates. Some very low death rate settings such as Eastern Asia, Central Europe, the Balkans and Africa have a common feature of eating large quantities of fermented foods whose intake is associated with the activation of the Nrf2 (Nuclear factor (erythroid-derived 2)-like 2) anti-oxidant transcription factor. There are many Nrf2-interacting nutrients (berberine, curcumin, epigallocatechin gallate, genistein, quercetin, resveratrol, sulforaphane) that all act similarly to reduce insulin resistance, endothelial damage, lung injury and cytokine storm. They also act on the same mechanisms (mTOR: Mammalian target of rapamycin, PPAR gamma:Peroxisome proliferator-activated receptor, NF kappa B: Nuclear factor kappa B, ERK: Extracellular signal-regulated kinases and eIF2 alpha:Elongation initiation factor 2 alpha). They may as a result be important in mitigating the severity of COVID-19, acting through the endoplasmic reticulum stress or ACE-Angiotensin-II-AT(1)R axis (AT(1)R) pathway. Many Nrf2-interacting nutrients are also interacting with TRPA1 and/or TRPV1. Interestingly, geographical areas with very low COVID-19 mortality are those with the lowest prevalence of obesity (Sub-Saharan Africa and Asia). It is tempting to propose that Nrf2-interacting foods and nutrients can re-balance insulin resistance and have a significant effect on COVID-19 severity. It is therefore possible that the intake of these foods may restore an optimal natural balance for the Nrf2 pathway and may be of interest in the mitigation of COVID-19 severity