RESUMO
Trees form symbioses with ectomycorrhizal (ECM) fungi, maintained in part through mutual benefit to both organisms. Our understanding of the signaling events leading to the successful interaction between the two partners requires further study. This is especially true for understanding the role of volatile signals produced by ECM fungi. Terpenoids are a predominant class of volatiles produced by ECM fungi. While several ECM genomes are enriched in the enzymes responsible for the production of these volatiles (i.e., terpene synthases (TPSs)) when compared to other fungi, we have limited understanding of the biochemical products associated with each enzyme and the physiological impact of specific terpenes on plant growth. Using a combination of phylogenetic analyses, RNA sequencing, and functional characterization of five TPSs from two distantly related ECM fungi (Laccaria bicolor and Pisolithus microcarpus), we investigated the role of these secondary metabolites during the establishment of symbiosis. We found that despite phylogenetic divergence, these TPSs produced very similar terpene profiles. We focused on the role of P. microcarpus terpenes and found that the fungus expressed a diverse array of mono-, di-, and sesquiterpenes prior to contact with the host. However, these metabolites were repressed following physical contact with the host Eucalyptus grandis. Exposure of E. grandis to heterologously produced terpenes (enriched primarily in γ -cadinene) led to a reduction in the root growth rate and an increase in P. microcarpus-colonized root tips. These results support a very early putative role of fungal-produced terpenes in the establishment of symbiosis between mycorrhizal fungi and their hosts.
Assuntos
Basidiomycota , Micorrizas , Sesquiterpenos , Micorrizas/fisiologia , Raízes de Plantas/metabolismo , Filogenia , Simbiose/fisiologia , Sesquiterpenos/metabolismoRESUMO
INTRODUCTION: Hypoxaemia and hyperoxaemia may occur after surgery, with related complications. This multicentre randomised trial evaluated the impact of automated closed-loop oxygen administration after high-risk abdominal or thoracic surgeries in terms of optimising the oxygen saturation measured by pulse oximetry time within target range. METHODS: After extubation, patients with an intermediate to high risk of post-operative pulmonary complications were randomised to "standard" or "automated" closed-loop oxygen administration. The primary outcome was the percentage of time within the oxygenation range, during a 3-day frame. The secondary outcomes were the time with hypoxaemia and hyperoxaemia under oxygen. RESULTS: Among the 200 patients, time within range was higher in the automated group, both initially (≤3â h; 91.4±13.7% versus 40.2±35.1% of time, difference +51.0% (95% CI -42.8-59.2%); p<0.0001) and during the 3-day period (94.0±11.3% versus 62.1±23.3% of time, difference +31.9% (95% CI 26.3-37.4%); p<0.0001). Periods of hypoxaemia were reduced in the automated group (≤3â days; 32.6±57.8 min (1.2±1.9%) versus 370.5±594.3â min (5.0±11.2%), difference -10.2% (95% CI -13.9--6.6%); p<0.0001), as well as hyperoxaemia under oxygen (≤3â days; 5.1±10.9 min (4.8±11.2%) versus 177.9±277.2â min (27.0±23.8%), difference -22.0% (95% CI -27.6--16.4%); p<0.0001). Kaplan-Meier analysis depicted a significant difference in terms of hypoxaemia (p=0.01) and severe hypoxaemia (p=0.0003) occurrence between groups in favour of the automated group. 25 patients experienced hypoxaemia for >10% of the entire monitoring time during the 3â days within the standard group, as compared to the automated group (p<0.0001). CONCLUSION: Automated closed-loop oxygen administration promotes greater time within the oxygenation target, as compared to standard manual administration, thus reducing the occurrence of hypoxaemia and hyperoxaemia.
Assuntos
Cirurgia Torácica , Procedimentos Cirúrgicos Torácicos , Humanos , Hipóxia , Oximetria , OxigênioRESUMO
The aim of this study was to compare bone mineral content (BMC), bone mineral density (BMD), and geometric indices of hip bone strength among 3 groups of adult obese premenopausal women (severely obese, morbidly obese, and super morbidly obese). This study included 65 young adult premenopausal women whose body mass index (BMI) > 35 kg/m2. They were divided into 3 groups using international cut-offs for BMI. Body composition and bone variables were measured by DXA. DXA measurements were completed for the whole body (WB), lumbar spine, total hip (TH), and femoral neck (FN). Geometric indices of FN strength (cross-sectional area, cross-sectional moment of inertia [CSMI], section modulus [Z], strength index [SI], and buckling ratio) were calculated by DXA. Results showed that age and height were not significantly different among the 3 groups. WB BMC values were higher in super morbidly obese women compared to severely and morbidly obese women. WB BMD, L1-L4 BMD, total hip BMD, FN BMD, cross-sectional area, CSMI, Z, and buckling ratio values were not significantly different among the 3 groups. SI values were lower in super morbidly obese compared to morbidly and severely obese women. In the whole population (nâ¯=â¯65), body weight, BMI, lean mass, fat mass, and trunk fat mass were positively correlated to WB BMC and negatively correlated to SI. Weight and lean mass were positively correlated to WB BMD and CSMI. Our findings suggest that the severity of obesity does not influence BMD values in premenopausal women.
Assuntos
Densidade Óssea , Obesidade Mórbida , Absorciometria de Fóton , Composição Corporal , Índice de Massa Corporal , Feminino , Colo do Fêmur , Humanos , Obesidade Mórbida/diagnóstico por imagem , Pré-Menopausa , Adulto JovemRESUMO
INTRODUCTION: The aim of this study was to compare bone mineral density (BMD) and geometric indices of hip bone strength in a group of obese sarcopenic premenopausal women (n = 27) and a group of obese premenopausal women with normal appendicular lean mass (ALM)/body mass index ratio (BMI) (n = 26). MATERIALS AND METHODS: The ALM/BMI criterion of The Foundation for the National Institute of Health was used; women with an ALM/BMI ratio < 0.512 m2 were considered obese sarcopenic. Body composition and bone variables were measured by DXA. DXA measurements were completed for the whole body (WB), lumbar spine (L1-L4), total hip (TH) and femoral neck (FN). Hip geometry parameters including cross-sectional area (CSA), cross-sectional moment of inertia (CSMI), section modulus (Z), strength index (SI) and buckling ratio (BR) were derived by DXA. RESULTS: Age, weight and BMI were not significantly different between the two groups. Height, lean mass, skeletal muscle mass index, ALM and the ratio ALM/BMI were significantly higher in obese women with normal ALM/BMI ratio compared to obese sarcopenic women. Fat mass percentage was significantly higher in obese sarcopenic women compared to obese women with normal ALM/BMI ratio. WB BMC, TH BMD, FN BMD, CSA, CSMI and Z were significantly higher in obese women with normal ALM/BMI ratio compared to obese sarcopenic women. In the whole population (n = 53), ALM and the ratio ALM/BMI were positively correlated to WB BMC, CSA, CSMI and Z. CONCLUSION: The present study suggests that sarcopenia negatively influences bone mineral density and hip geometry parameters before menopause in eumenorrheic obese women.
Assuntos
Osso e Ossos/patologia , Obesidade/patologia , Pré-Menopausa/fisiologia , Sarcopenia/patologia , Absorciometria de Fóton , Adulto , Composição Corporal/fisiologia , Índice de Massa Corporal , Peso Corporal/fisiologia , Densidade Óssea/fisiologia , Osso e Ossos/diagnóstico por imagem , Feminino , Humanos , Obesidade/complicações , Obesidade/diagnóstico por imagem , Sarcopenia/complicações , Sarcopenia/diagnóstico por imagemRESUMO
Importance: It is not known if use of colloid solutions containing hydroxyethyl starch (HES) to correct for intravascular deficits in high-risk surgical patients is either effective or safe. Objective: To evaluate the effect of HES 130/0.4 compared with 0.9% saline for intravascular volume expansion on mortality and postoperative complications after major abdominal surgery. Design, Setting, and Participants: Multicenter, double-blind, parallel-group, randomized clinical trial of 775 adult patients at increased risk of postoperative kidney injury undergoing major abdominal surgery at 20 university hospitals in France from February 2016 to July 2018; final follow-up was in October 2018. Interventions: Patients were randomized to receive fluid containing either 6% HES 130/0.4 diluted in 0.9% saline (n = 389) or 0.9% saline alone (n = 386) in 250-mL boluses using an individualized hemodynamic algorithm during surgery and for up to 24 hours on the first postoperative day, defined as ending at 7:59 am the following day. Main Outcomes and Measures: The primary outcome was a composite of death or major postoperative complications at 14 days after surgery. Secondary outcomes included predefined postoperative complications within 14 days after surgery, durations of intensive care unit and hospital stays, and all-cause mortality at postoperative days 28 and 90. Results: Among 826 patients enrolled (mean age, 68 [SD, 7] years; 91 women [12%]), 775 (94%) completed the trial. The primary outcome occurred in 139 of 389 patients (36%) in the HES group and 125 of 386 patients (32%) in the saline group (difference, 3.3% [95% CI, -3.3% to 10.0%]; relative risk, 1.10 [95% CI, 0.91-1.34]; P = .33). Among 12 prespecified secondary outcomes reported, 11 showed no significant difference, but a statistically significant difference was found in median volume of study fluid administered on day 1: 1250 mL (interquartile range, 750-2000 mL) in the HES group and 1500 mL (interquartile range, 750-2150 mL) in the saline group (median difference, 250 mL [95% CI, 83-417 mL]; P = .006). At 28 days after surgery, 4.1% and 2.3% of patients had died in the HES and saline groups, respectively (difference, 1.8% [95% CI, -0.7% to 4.3%]; relative risk, 1.76 [95% CI, 0.79-3.94]; P = .17). Conclusions and Relevance: Among patients at risk of postoperative kidney injury undergoing major abdominal surgery, use of HES for volume replacement therapy compared with 0.9% saline resulted in no significant difference in a composite outcome of death or major postoperative complications within 14 days after surgery. These findings do not support the use of HES for volume replacement therapy in such patients. Trial Registration: ClinicalTrials.gov Identifier: NCT02502773.
Assuntos
Abdome/cirurgia , Hidratação/métodos , Derivados de Hidroxietil Amido/uso terapêutico , Complicações Pós-Operatórias/prevenção & controle , Solução Salina/uso terapêutico , Procedimentos Cirúrgicos Operatórios/efeitos adversos , Injúria Renal Aguda/prevenção & controle , Idoso , Método Duplo-Cego , Feminino , Humanos , Cuidados Intraoperatórios , Masculino , Pessoa de Meia-Idade , Cuidados Pós-Operatórios , Complicações Pós-Operatórias/epidemiologia , Complicações Pós-Operatórias/mortalidade , Estatísticas não ParamétricasRESUMO
RATIONALE: Assessment of fluid responsiveness relies on dynamic echocardiographic parameters that have not yet been compared in large cohorts. OBJECTIVES: To determine the diagnostic accuracy of dynamic parameters used to predict fluid responsiveness in ventilated patients with a circulatory failure of any cause. METHODS: In this multicenter prospective study, respiratory variations of superior vena cava diameter (∆SVC) measured using transesophageal echocardiography, of inferior vena cava diameter (∆IVC) measured using transthoracic echocardiography, of the maximal Doppler velocity in left ventricular outflow tract (∆VmaxAo) measured using either approach, and pulse pressure variations (∆PP) were recorded with the patient in the semirecumbent position. In each patient, a passive leg raise was performed and an increase of aortic velocity time integral greater than or equal to 10% defined fluid responsiveness. MEASUREMENTS AND MAIN RESULTS: Among 540 patients (379 men; age, 65 ± 13 yr; Simplified Acute Physiological Score II, 59 ± 18; Sequential Organ Failure Assessment, 10 ± 3), 229 exhibited fluid responsiveness (42%). ∆PP, ∆VmaxAo, ∆SVC, and ∆IVC could be measured in 78.5%, 78.0%, 99.6%, and 78.1% of cases, respectively. ∆SVC greater than or equal to 21%, ∆VmaxAo greater than or equal to 10%, and ∆IVC greater than or equal to 8% had a sensitivity of 61% (95% confidence interval, 57-66%), 79% (75-83%), and 55% (50-59%), respectively, and a specificity of 84% (81-87%), 64% (59-69%), and 70% (66-75%), respectively. The area under the receiver operating characteristic curve of ∆SVC was significantly greater than that of ∆IVC (P = 0.02) and ∆PP (P = 0.01). CONCLUSIONS: ∆VmaxAo had the best sensitivity and ∆SVC the best specificity in predicting fluid responsiveness. ∆SVC had a greater diagnostic accuracy than ∆IVC and ∆PP, but its measurement requires transesophageal echocardiography.
Assuntos
Ecocardiografia/métodos , Hidratação , Respiração Artificial , Veia Cava Inferior/fisiopatologia , Veia Cava Superior/fisiopatologia , Idoso , Ecocardiografia Doppler , Ecocardiografia Transesofagiana , Feminino , Humanos , Masculino , Estudos Prospectivos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Veia Cava Inferior/diagnóstico por imagem , Veia Cava Superior/diagnóstico por imagemRESUMO
Modular polyketide synthases (PKSs) direct the biosynthesis of clinically valuable secondary metabolites in bacteria. The fidelity of chain growth depends on specific recognition between successive subunits in each assembly line: interactions mediated by C- and N-terminal "docking domains" (DDs). We have identified a new family of DDs in trans-acyl transferase PKSs, exemplified by a matched pair from the virginiamycin (Vir) system. In the absence of C-terminal partner (VirA (C)DD) or a downstream catalytic domain, the N-terminal DD (VirFG (N)DD) exhibits multiple characteristics of an intrinsically disordered protein. Fusion of the two docking domains results in a stable fold for VirFG (N)DD and an overall protein-protein complex of unique topology whose structure we support by site-directed mutagenesis. Furthermore, using small-angle X-ray scattering (SAXS), the positions of the flanking acyl carrier protein and ketosynthase domains have been identified, allowing modeling of the complete intersubunit interface.
Assuntos
Aciltransferases/metabolismo , Policetídeo Sintases/metabolismo , Virginiamicina/química , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Virginiamicina/metabolismoRESUMO
TlpAs (thioredoxin-like proteins) are bacterial thioredoxin-like periplasmic disulfide oxidoreductases generally involved in cytochrome c maturation (Ccm) process. They contain a characteristic CXXC active site motif involved in disulfide exchange reaction. In the human pathogenic Neisseria meningitidis species, no TlpA has been characterized so far. In the present study, using an in silico analysis, we identified a putative periplasmic TlpA, called TlpA2. Biochemical and kinetic characterizations of the soluble form of TlpA2, tTlpA2 (truncated TlpA2), were performed. A reduction potential of -0.230 V at pH 7 was calculated, suggesting that TlpA2 acts as a reductant in the oxidative environment of the periplasm. Using a second-order reactive probe, high pKapp (apparent pKa) values were determined for the two cysteines of the SCXXC motif. The tTlpA2 was shown to be efficiently reduced by the N-terminal domain of the DsbD, whereas tTlpA2 reduced a mimetic peptide of cytochrome c' with a catalytic efficiency similar to that observed with other disulfide oxidoreductase like ResA. Moreover, the corresponding gene tlpA2 was shown to be essential for the pathogen viability and able to partially complement a Bordetella pertussis CcsX mutant. Together, these data support an essential role of TlpA2 in the Ccm process in N. meningitidis.
Assuntos
Dissulfetos/metabolismo , Infecções Meningocócicas/patologia , Neisseria meningitidis/enzimologia , Oxirredutases/química , Oxirredutases/metabolismo , Periplasma/enzimologia , Proteínas Periplásmicas/química , Proteínas Periplásmicas/metabolismo , Tiorredoxinas/metabolismo , Sequência de Aminoácidos , Domínio Catalítico , Humanos , Infecções Meningocócicas/metabolismo , Infecções Meningocócicas/microbiologia , Modelos Moleculares , Dados de Sequência Molecular , Oxirredução , Estrutura Terciária de Proteína , Homologia de Sequência de AminoácidosRESUMO
Modular polyketide synthases (PKSs) are multidomain multienzymes responsible for the biosynthesis in bacteria of a wide range of polyketide secondary metabolites of clinical value. The stereochemistry of these molecules is an attractive target for genetic engineering in attempts to produce analogues exhibiting novel therapeutic properties. The exchange of ketoreductase (KR) domains in model PKSs has been shown in several cases to predictably alter the configuration of the ß-hydroxy functionalities but not of the α-methyl groups. By systematic screening of a broad panel of KR domains, we have identified two donor KRs that afford modification of α-methyl group stereochemistry. To the best of our knowledge, this provides the first direct in vivo evidence of KR-catalyzed epimerization. However, none of the introduced KRs afforded simultaneous alteration of methyl and hydroxy configurations in high yield. Therefore, swapping of whole modules might be necessary to achieve such changes in stereochemistry.
Assuntos
Oxirredutases do Álcool/metabolismo , Proteínas de Bactérias/metabolismo , Policetídeo Sintases/metabolismo , Policetídeos/metabolismo , Engenharia de Proteínas , Streptomyces/enzimologia , Oxirredutases do Álcool/química , Oxirredutases do Álcool/genética , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Policetídeo Sintases/química , Policetídeo Sintases/genética , Policetídeos/química , Estrutura Terciária de Proteína , Estereoisomerismo , Streptomyces/química , Streptomyces/genética , Streptomyces/metabolismo , Especificidade por SubstratoRESUMO
This study aimed to determine whether aerobic training could reduce lipid peroxidation and inflammation at rest and after maximal exhaustive exercise in overweight/obese adolescent girls. Thirty-nine adolescent girls (14-19 years old) were classified as nonobese or overweight/obese and then randomly assigned to either the nontrained or trained group (12-week multivariate aerobic training program). Measurements at the beginning of the experiment and at 3 months consisted of body composition, aerobic fitness (VO2peak) and the following blood assays: pre- and postexercise lipid peroxidation (15F2a-isoprostanes [F2-Isop], lipid hydroperoxide [ROOH], oxidized LDL [ox-LDL]) and inflammation (myeloperoxidase [MPO]) markers. In the overweight/ obese group, the training program significantly increased their fat-free mass (FFM) and decreased their percentage of fat mass (%FM) and hip circumference but did not modify their VO2peak. Conversely, in the nontrained overweight/obese group, weight and %FM increased, and VO2peak decreased, during the same period. Training also prevented exercise-induced lipid peroxidation and/or inflammation in overweight/obese girls (F2-Isop, ROOH, ox-LDL, MPO). In addition, in the trained overweight/obese group, exercise-induced changes in ROOH, ox-LDL and F2-Isop were correlated with improvements in anthropometric parameters (waist-to-hip ratio, %FM and FFM). In conclusion aerobic training increased tolerance to exercise-induced oxidative stress in overweight/obese adolescent girls partly as a result of improved body composition.
Assuntos
Terapia por Exercício/métodos , Exercício Físico/fisiologia , Inflamação , Peroxidação de Lipídeos , Sobrepeso/terapia , Adolescente , Biomarcadores/sangue , Composição Corporal , Feminino , Humanos , Inflamação/sangue , Inflamação/diagnóstico , Inflamação/etiologia , Obesidade/sangue , Obesidade/fisiopatologia , Obesidade/terapia , Sobrepeso/sangue , Sobrepeso/fisiopatologia , Estresse Oxidativo , Peroxidase/sangue , Resultado do Tratamento , Adulto JovemRESUMO
INTRODUCTION: The aim of this study was to explore the relationship between sleep quality and bone mineral density (BMD) of the hip in a group of young Lebanese men. METHODS AND RESULTS: Fourteen Lebanese young men from 18 to 30 years (mean age 22.6 years) participated in this study. Weight and height were measured and body mass index (BMI) was calculated. BMD of the total hip (TH) and the femoral neck (FN) was measured by DXA. Daily protein intake (DPI), daily calcium intake (DCI) and sleep quality were evaluated by validated questionnaires. The Pittsburgh sleep quality index (PSQI) was used to assess sleep habits and quality; higher scores represent worse sleep quality. Weight, height, BMI, DCI, DPI and sleep duration were not correlated to BMD values. The Pittsburgh sleep quality index was negatively correlated to femoral neck BMD (r = -0.82; p < 0.001) and to TH BMD (r = -0.54; p < 0.05). CONCLUSION: This study suggests that poor sleep quality affects negatively BMD of the hip in young adult men. Our findings may lead to the development of better preventive approaches to osteoporosis.
Assuntos
Densidade Óssea/fisiologia , Colo do Fêmur/fisiologia , Sono/fisiologia , Absorciometria de Fóton , Adolescente , Adulto , Colo do Fêmur/diagnóstico por imagem , Humanos , Líbano , Masculino , Adulto JovemRESUMO
BACKGROUND: In the perioperative setting, the most accurate way to continuously measure arterial blood pressure (ABP) is using an arterial catheter. Surrogate methods such as finger cuff have been developed to allow non-invasive measurements and are increasingly used, but need further evaluation. The aim of this study is to evaluate the accuracy and clinical concordance between two devices for the measurement of ABP during neuroradiological procedure. METHODS: This is a prospective, monocentric, observational study. All consecutive patients undergoing a neuroradiological procedure were eligible. Patients who needed arterial catheter for blood pressure measurement were included. During neuroradiological procedure, ABP (systolic, mean and diatolic blood pressure) was measured with two different technologies: radial artery catheter and Nexfin. Bland-Altman and error grid analyses were performed to evaluate the accuracy and clinical concordance between devices. RESULTS: From March 2022 to November 2022, we included 50 patients, mostly ASA 3 (60%) and required a cerebral embolization (94%) under general anaesthesia (96%). Error grid analysis showed that 99% of non-invasive ABP measures obtained with the Nexfin were located in the risk zone A or B. However, 65.7% of hypertension events and 41% of hypotensive events were respectively not detected by Nexfin. Compared to the artery catheter, a significant relationship was found for SAP (r2 = 0.78) and MAP (r2 = 0.80) with the Nexfin (p < 0.001). Bias and limits of agreement (LOA) were respectively 9.6 mmHg (- 15.6 to 34.8 mmHg) and - 0.8 mmHg (- 17.2 to 15.6 mmHg), for SAP and MAP. CONCLUSIONS: Nexfin is not strictly interchangeable with artery catheter for ABP measuring. Further studies are needed to define its clinical use during neuroradiological procedure. TRIAL REGISTRATION: Clinicaltrials.gov, registration number: NCT05283824.
RESUMO
The aim of this study was to compare hip bone strength indices in obese, overweight, and normal-weight adolescent girls using hip structure analysis (HSA). This study included 64 postmenarcheal adolescent girls (14 obese, 21 overweight, and 29 normal weight). The 3 groups (obese, overweight, and normal weight) were matched for maturity (years since menarche). Body composition and bone mineral density (BMD) of whole body, lumbar spine, and proximal femur were assessed by dual-energy X-ray absorptiometry (DXA). To evaluate hip bone strength, DXA scans were analyzed at the femoral neck (FN) at its narrow neck (NN) region, the intertrochanteric (IT), and the femoral shaft (FS) by the HSA program. Cross-sectional area and section modulus were measured from hip BMD profiles. Total hip BMD and FN BMD were significantly higher in obese and overweight girls in comparison with normal-weight girls (p < 0.05). However, after adjusting for weight, using a one-way analysis of covariance, there were no significant differences among the 3 groups regarding HSA variables. This study suggests that in obese and overweight adolescent girls, axial strength and bending strength indices of the NN, IT, and FS are adapted to the increased body weight.
Assuntos
Absorciometria de Fóton/métodos , Densidade Óssea/fisiologia , Obesidade/diagnóstico por imagem , Sobrepeso/diagnóstico por imagem , Ossos Pélvicos/diagnóstico por imagem , Adolescente , Índice de Massa Corporal , Feminino , Seguimentos , Quadril , Humanos , Adulto JovemRESUMO
AIM OF THE STUDY: The aim of this study was to compare bone mineral content (BMC), bone mineral density (BMD) and bone mineral apparent density (BMAD) in obese, overweight and normal weight adolescent boys. METHODS & RESULTS: This study included 23 obese, 19 overweight and 25 normal weight adolescents (aged 14-20 years) boys. The three groups (obese, overweight and normal weight) were matched for age and maturation index. Body composition, BMC and BMD were assessed by dual-energy X-ray absorptiometry (DXA). The expressions whole body (WB) BMC/height and WB BMD/height were used to adjust for WB bone size. BMAD was calculated for the WB. WB BMC, WB BMC/height, total hip (TH) BMD, femoral neck (FN) BMD and ultra distal (UD) radius BMD) were higher in obese and overweight boys in comparison to normal weight boys (p < 0.05). WB BMAD was lower in obese boys in comparison to overweight and normal weight boys (p < 0.05). After adjustment for either weight or lean mass, obese boys displayed lower WB BMC, WB BMC/height and WB BMD values in comparison to overweight and normal weight boys (p < 0.05). CONCLUSION: This study suggests that WB BMC, WB BMC/height and WB BMD do not adapt to the increased body weight in obese adolescent boys.
Assuntos
Densidade Óssea/fisiologia , Países em Desenvolvimento , Obesidade/fisiopatologia , Sobrepeso/fisiopatologia , Adolescente , Índice de Massa Corporal , Peso Corporal/fisiologia , Humanos , Líbano , Masculino , Programas de Rastreamento , Valores de Referência , Adulto JovemRESUMO
During biosynthesis by multi-modular trans-AT polyketide synthases, polyketide structural space can be expanded by conversion of initially-formed electrophilic ß-ketones into ß-alkyl groups. These multi-step transformations are catalysed by 3-hydroxy-3-methylgluratryl synthase cassettes of enzymes. While mechanistic aspects of these reactions have been delineated, little information is available concerning how the cassettes select the specific polyketide intermediate(s) to target. Here we use integrative structural biology to identify the basis for substrate choice in module 5 of the virginiamycin M trans-AT polyketide synthase. Additionally, we show in vitro that module 7, at minimum, is a potential additional site for ß-methylation. Indeed, analysis by HPLC-MS coupled with isotopic labelling and pathway inactivation identifies a metabolite bearing a second ß-methyl at the expected position. Collectively, our results demonstrate that several control mechanisms acting in concert underpin ß-branching programming. Furthermore, variations in this control - whether natural or by design - open up avenues for diversifying polyketide structures towards high-value derivatives.
Assuntos
Streptomyces , Metilação , Virginiamicina/biossíntese , Virginiamicina/química , Streptomyces/metabolismo , Ligação Proteica , Modelos Moleculares , Estrutura Terciária de Proteína , Especificidade por SubstratoRESUMO
OBJECTIVE: The aim of this study was to compare femoral shaft and intertrochanteric geometry in overweight and normal weight adolescent girls. METHODS AND RESULTS: This study included 22 overweight (Body mass index (BMI) > 25 kg/m2) adolescent girls (15.4 +/- 2.4 years old) and 20 maturation-matched (15.2 +/- 1.9 years old) controls (BMI < 25 kg/m2). Body composition and BMD were assessed by dual-energy X-ray absorptiometry (DXA). To evaluate bone geometry, DXA scans were analyzed at the femoral shaft and the intertrochanteric region by the Hip Structure Analysis (HSA) program. Cross-sectional area (CSA), an index of axial compression strength, section modulus (Z), an index of bending strength, cross-sectional moment of inertia (CSMI), cortical thickness (CT) and buckling ratio (BR) were measured from bone mass profiles. Lean mass, body weight, fat mass and BMI were higher in overweight girls compared to controls (p < 0.001). CSA, Z, CSMI and CT were higher in overweight girls compared to controls (p < 0.05) at the two regions (femoral shaft and intertrochanteric). After adjustment for maturation index (years since menarche), CSA, Z, CSMI and CT of the intertrochanteric region and CSA of the femoral shaft were higher in overweight girls compared to controls (p < 0.05). After adjustment for either body weight, lean mass or BMI, using a one-way analysis of covariance (ANCOVA), there were no differences between the two groups (overweight and controls) regarding the HSA variables (CSA, CSMI, Z, CT and BR) at the femoral shaft and the intertrochanteric. CONCLUSION: This study suggests that overweight adolescent girls have greater indices of bone axial and bending strength in comparison to controls at the intertrochanteric after adjustment for maturation index.
Assuntos
Articulação do Quadril/diagnóstico por imagem , Articulação do Quadril/fisiologia , Sobrepeso/fisiopatologia , Absorciometria de Fóton , Adolescente , Densidade Óssea/fisiologia , Estudos de Casos e Controles , Criança , Feminino , Humanos , Comportamento Sedentário , Adulto JovemRESUMO
The CRISPR/Cas system, which has been widely applied to organisms ranging from microbes to animals, is currently being adapted for use in Streptomyces bacteria. In this case, it is notably applied to rationally modify the biosynthetic pathways giving rise to the polyketide natural products, which are heavily exploited in the medical and agricultural arenas. Our aim here is to provide the potential user with a practical guide to exploit this approach for manipulating polyketide biosynthesis, by treating key experimental aspects including vector choice, design of the basic engineering components, and trouble-shooting.
Assuntos
Policetídeos , Streptomyces , Animais , Vias Biossintéticas/genética , Sistemas CRISPR-Cas/genética , Edição de Genes , Policetídeos/metabolismo , RNA Guia de Cinetoplastídeos/genética , RNA Guia de Cinetoplastídeos/metabolismo , Streptomyces/genética , Streptomyces/metabolismoRESUMO
The modular organization of the type I polyketide synthases (PKSs) would seem propitious for rational engineering of desirable analogous. However, despite decades of efforts, such experiments remain largely inefficient. Here, we combine multiple, state-of-the-art approaches to reprogram the stambomycin PKS by deleting seven internal modules. One system produces the target 37-membered mini-stambomycin metabolites - a reduction in chain length of 14 carbons relative to the 51-membered parental compounds - but also substantial quantities of shunt metabolites. Our data also support an unprecedented off-loading mechanism of such stalled intermediates involving the C-terminal thioesterase domain of the PKS. The mini-stambomycin yields are reduced relative to wild type, likely reflecting the poor tolerance of the modules downstream of the modified interfaces to the non-native substrates. Overall, we identify factors contributing to the productivity of engineered whole assembly lines, but our findings also highlight the need for further research to increase production titers.
Assuntos
Macrolídeos/metabolismo , Engenharia Metabólica , Policetídeo Sintases/genética , Policetídeo Sintases/metabolismo , Sequência de Aminoácidos , Macrolídeos/química , Complexos Multienzimáticos , Especificidade por Substrato , Biologia SintéticaRESUMO
The purpose of this study was to analyse the relationships between age, morphological characteristics (weight, height, body mass index (BMI), fat and lean mass), daily calcium intake (DCI), physical activity and bone mineral apparent density (BMAD) of the whole body (WB), lumbar spine (L2-L4), femoral neck (FN) and 1/3 radius in a group of Lebanese adolescent boys. This study included 60 Lebanese adolescent (16.8 ± 2.1 years old) boys. Body composition and bone mineral density (BMD) were assessed by dual-energy X-ray absorptiometry (DXA). BMAD values of the WB, L2-L4, FN and 1/3 radius were calculated. Physical activity and DCI were assessed using questionnaires. Age was positively related to WB, L2-L4 and 1/3 radius BMD and BMAD. Weight, lean mass and BMI were positively related to WB, L2-L4, FN and 1/3 radius BMD. Moreover, weight, lean mass and BMI were positively associated with L2-L4 and FN BMAD but not with BMAD of the WB and the 1/3 radius, while fat mass percentage was negatively associated with WB BMAD. In conclusion, this study shows that weight, lean mass and BMI are positively associated with BMAD of the weight-bearing bones (L2-L4 and FN) but not with BMAD of the WB and the 1/3 radius in adolescent boys.
Assuntos
Envelhecimento/fisiologia , Densidade Óssea/fisiologia , Colo do Fêmur/anatomia & histologia , Colo do Fêmur/fisiologia , Vértebras Lombares/anatomia & histologia , Vértebras Lombares/fisiologia , Rádio (Anatomia)/fisiologia , Adolescente , Humanos , Líbano , Masculino , Rádio (Anatomia)/anatomia & histologiaRESUMO
The influence of being overweight on bone strength in adolescents remains controversial. The aim of this study was to compare hip bone strength indices in overweight and control adolescent boys using hip structure analysis (HSA). This study included 25 overweight adolescent boys [body mass index (BMI) >25 kg/m(2)] and 31 maturation-matched controls (BMI <25 kg/m(2)). Body composition and bone mineral density were assessed by dual-energy X-ray absorptiometry (DXA). To evaluate hip bone strength, DXA scans were analyzed at femoral neck, intertrochanteric, and femoral shaft by the HSA program. Cross-sectional area (CSA), an index of axial compression strength, section modulus (Z), an index of bending strength, cross-sectional moment of inertia (CSMI), cortical thickness (CT), and buckling ratio (BR) were measured from bone mass profiles. Body weight, lean mass, fat mass, and BMI were higher in overweight boys compared to controls (P < 0.001). CSA, CSMI, and Z of the three sites (femoral neck, intertrochanteric, and femoral shaft) were higher in overweight boys compared to controls (P < 0.01). BR was not significantly different between the two groups at the three sites. After adjustment for either body weight, BMI, or fat mass, using a one-way analysis of covariance, there were no differences between the two groups regarding the HSA variables (CSA, Z, CSMI, CT, and BR). After adjusting for lean mass, overweight boys displayed higher values of femoral shaft CSA, CSMI, and Z in comparison to controls (P < 0.05). In conclusion, this study suggests that overweight adolescent boys have greater indices of bone axial and bending strength in comparison to controls at the femoral neck, the intertrochanteric, and the femoral shaft.