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1.
Spectrochim Acta A Mol Biomol Spectrosc ; 315: 124261, 2024 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-38608560

RESUMO

Food safety is always of paramount importance globally due to the devasting social and economic effects of foodborne disease outbreaks. There is a high consumption rate of meat worldwide, making it an essential protein source in the human diet, hence its microbial safety is of great importance. The food industry stakeholders are always in search of methods that ensure safe food whilst maintaining food quality and excellent sensory attributes. Currently, there are several methods used in microbial food analysis, however, these methods are often time-consuming and do not allow real-time analysis. Considering the recent technological breakthroughs in artificial intelligence and machine learning, it raises the question of whether these advancements could be leveraged within the meat industry to improve turnaround time for microbial assessments. Hyperspectral imaging (HSI) is a highly prospective technology worth exploring for microbial analysis. The rapid, non-destructive method has the potential to be integrated into food production systems and allows foodborne pathogen detection in food samples, thus saving time. Although there has been a substantial increase in research on the utilisation of HSI in food applications over the past years, its use in the microbial assessment of meat is not yet optimal. This review aims to provide a basic understanding of the visible-near infrared HSI system, recent applications in the microbial assessment of meat products, challenges, and possible future applications.

2.
J Clin Med ; 13(7)2024 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-38610673

RESUMO

Background: Long COVID (LC) is a multisystem clinical syndrome with functional disability and compromised overall health. Information on LC clinical severity types is emerging in cross-sectional studies. This study explored the pattern and consistency of long COVID (LC) clinical severity types over time in a prospective sample. Methods: Participants with LC completed the condition-specific outcome measure C19-YRSm (Yorkshire Rehabilitation Scale modified version) at two assessment time points. A cluster analysis for clinical severity types was undertaken at both time points using the k-means partition method. Results: The study included cross-sectional data for 759 patients with a mean age of 46.8 years (SD = 12.7), 69.4% females, and a duration of symptoms of 360 days (IQR 217 to 703 days). The cluster analysis at first assessment revealed three distinct clinical severity type clusters: mild (n = 96), moderate (n = 422), and severe (n = 241). Longitudinal data on 356 patients revealed that the pattern of three clinical severity types remained consistent over time between the two assessments, with 51% of patients switching clinical severity types between the assessments. Conclusions: This study is the first of its kind to demonstrate that the pattern of three clinical severity types is consistent over time, with patients also switching between severity types, indicating the fluctuating nature of LC.

3.
bioRxiv ; 2024 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-38585740

RESUMO

Aggression, a sexually dimorphic behaviour, is prevalent in males and typically absent in virgin females. Following parturition, however, the transient expression of aggression in adult female mice protects pups from predators and infanticide by male conspecifics. While maternal hormones are known to elicit nursing, their potential role in maternal aggression remains elusive. Here, we show in mice that a molecularly defined subset of ventral premammillary (PMvDAT) neurons, instrumental for intermale aggression, switch from quiescence to a hyperexcitable state during lactation. We identify that the maternal hormones prolactin and oxytocin excite these cells through actions that include T-type Ca2+ channels. Optogenetic manipulation or genetic ablation of PMvDAT neurons profoundly affects maternal aggression, while activation of these neurons impairs the expression of non-aggression-related maternal behaviours. This work identifies a monomorphic neural substrate that can incorporate hormonal cues to enable the transient expression of a dormant behavioural program in lactating females.

4.
Adv Parasitol ; 123: 51-123, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38448148

RESUMO

The ascarids are a large group of parasitic nematodes that infect a wide range of animal species. In humans, they cause neglected diseases of poverty; many animal parasites also cause zoonotic infections in people. Control measures include hygiene and anthelmintic treatments, but they are not always appropriate or effective and this creates a continuing need to search for better ways to reduce the human, welfare and economic costs of these infections. To this end, Le Studium Institute of Advanced Studies organized a two-day conference to identify major gaps in our understanding of ascarid parasites with a view to setting research priorities that would allow for improved control. The participants identified several key areas for future focus, comprising of advances in genomic analysis and the use of model organisms, especially Caenorhabditis elegans, a more thorough appreciation of the complexity of host-parasite (and parasite-parasite) communications, a search for novel anthelmintic drugs and the development of effective vaccines. The participants agreed to try and maintain informal links in the future that could form the basis for collaborative projects, and to co-operate to organize future meetings and workshops to promote ascarid research.


Assuntos
Anti-Helmínticos , Zoonoses , Animais , Humanos , Zoonoses/prevenção & controle , Caenorhabditis elegans , Academias e Institutos , Pesquisa , Anti-Helmínticos/uso terapêutico
5.
Chest ; 2024 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-38508334

RESUMO

BACKGROUND: Pulmonary hypertension (PH) is a heterogeneous disease with poor prognosis. Accurate risk stratification is essential for guiding treatment decisions in pulmonary arterial hypertension (PAH). While various risk models were developed for PAH, their comparative prognostic potential requires further exploration. Additionally, the applicability of risk scores in PH groups beyond group 1 remains to be investigated. RESEARCH QUESTION: Are risk scores originally developed for PAH predictive in PH group 1-4? STUDY DESIGN AND METHODS: We conducted a comprehensive analysis of outcomes among incident PH patients enrolled in the multicenter worldwide PVRI-GoDeep meta-registry. Analyses were performed across PH groups 1-4 and further subgroups to evaluate the predictive value of PAH-risk scores, including REVEAL Lite 2, REVEAL 2.0, ESC/ERS 2022, COMPERA 3-strata and COMPERA 4-strata. RESULTS: 8565 patients were included in the study, of whom 3537 patients were assigned to group 1 PH while 1807, 1635, and 1586 patients were diagnosed with group 2, group 3, and group 4 PH. Pulmonary hemodynamics were impaired with median mPAP of 42 [33,52]mmHg and PVR of 7 [4,11]WU. All risk scores were prognostic in the entire PH population and in each of the PH groups 1-4. The REVEAL scores, when used as continuous prediction models, possessed the highest statistical prognostic power and granularity; the COMPERA 4-strata risk score provided sub-differentiation of the intermediate-risk group. Similar results were obtained when separately analyzing various subgroups (PH subgroups 1.1, 1.4.1, 1.4.4; 3.1, 3.2; group 2 with isolated post-capillary-PH versus combined pre-/post-capillary-PH; patients of all groups with concomitant cardiac comorbidities; severe [> 5 WU] versus non-severe PH). INTERPRETATION: This comprehensive study with real-world data from 15 PH-centers showed that PAH-designed risk scores possess predictive power in a large PH cohort, whether considered as common group or calculated separately for each PH group (1-4) and various subgroups.

6.
Cardiology ; 2024 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-38527430

RESUMO

Introduction The role of balloon aortic valvuloplasty (BAV) amid the era of transcatheter aortic valve replacement (TAVR) remains a topic of debate. We sought to study the safety and feasibility of combined balloon aortic valvuloplasty and percutaneous coronary intervention (BAV-PCI). Methods Between November 2009 and July 2020, all patients undergoing BAV were identified and divided into three groups: combined BAV-PCI (group A), BAV with significant unrevascularised CAD (group B) and BAV without significant CAD (group C). Procedural outcomes, 30-day and one-year mortality were compared. Results A total of 264 patients were studied (n = 84, 93 and 87 patients in group A, B and C, respectively). The STS score was 10.2 ±8, 13.3 ±19 and 8.1 ±7, p = 0.026, in group A, B and C, respectively. VARC-3 adjudicated complications were similar among groups (11%, 13% and 5%, respectively, p = 0.168, respectively). Thirty-day and one-year mortality were 9.8% (n =26) and 32% (n = 86) of the entire cohort. The differences among groups did not reach statistical significance. Using univariate Cox regression analysis, group B were at higher risk of dying compared to group A patients (HR 1.58, 95% CI 1.11 - 2.25, p = 0.010). With multivariate Cox regression analysis, the predictors of mortality were STS score, cardiogenic shock, and mode of presentation and lack of subsequent definitive valve intervention. Conclusion In high-risk patients with aortic valve stenosis, combined BAV-PCI is safe and feasible with comparable outcomes to BAV with and without significant CAD.

7.
J Med Virol ; 96(3): e29486, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38456315

RESUMO

Orthostatic intolerance (OI), including postural orthostatic tachycardia syndrome (PoTS) and orthostatic hypotension (OH), are often reported in long covid, but published studies are small with inconsistent results. We sought to estimate the prevalence of objective OI in patients attending long covid clinics and healthy volunteers and associations with OI symptoms and comorbidities. Participants with a diagnosis of long covid were recruited from eight UK long covid clinics, and healthy volunteers from general population. All undertook standardized National Aeronautics and Space Administration Lean Test (NLT). Participants' history of typical OI symptoms (e.g., dizziness, palpitations) before and during the NLT were recorded. Two hundred seventy-seven long covid patients and 50 frequency-matched healthy volunteers were tested. Healthy volunteers had no history of OI symptoms or symptoms during NLT or PoTS, 10% had asymptomatic OH. One hundred thirty (47%) long covid patients had previous history of OI symptoms and 144 (52%) developed symptoms during the NLT. Forty-one (15%) had an abnormal NLT, 20 (7%) met criteria for PoTS, and 21 (8%) had OH. Of patients with an abnormal NLT, 45% had no prior symptoms of OI. Relaxing the diagnostic thresholds for PoTS from two consecutive abnormal readings to one abnormal reading during the NLT, resulted in 11% of long covid participants (an additional 4%) meeting criteria for PoTS, but not in healthy volunteers. More than half of long covid patients experienced OI symptoms during NLT and more than one in 10 patients met the criteria for either PoTS or OH, half of whom did not report previous typical OI symptoms. We therefore recommend all patients attending long covid clinics are offered an NLT and appropriate management commenced.


Assuntos
COVID-19 , Intolerância Ortostática , Síndrome da Taquicardia Postural Ortostática , Estados Unidos , Humanos , Intolerância Ortostática/epidemiologia , Intolerância Ortostática/complicações , Intolerância Ortostática/diagnóstico , Síndrome Pós-COVID-19 Aguda , Prevalência , COVID-19/epidemiologia , COVID-19/complicações , Síndrome da Taquicardia Postural Ortostática/complicações , Síndrome da Taquicardia Postural Ortostática/diagnóstico
8.
Foods ; 13(2)2024 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-38254513

RESUMO

Determining egg freshness is critical for ensuring food safety and security and as such, different methods have been evaluated and implemented to accurately measure and predict it. In this study, a portable near-infrared (NIR) instrument combined with chemometrics was used to monitor and predict the storage time of eggs under two storage conditions-room temperature (RT) and cold (CT) storage-from two production systems: cage and free-range. A total of 700 egg samples were analyzed, using principal component analysis (PCA) and partial least squares (PLS) regression to analyze the NIR spectra. The PCA score plot did not show any clear separation between egg samples from the two production systems; however, some egg samples were grouped according to storage conditions. The cross-validation statistics for predicting storage time were as follows: for cage and RT eggs, the coefficient of determination in cross validation (R2CV) was 0.67, with a standard error in cross-validation (SECV) of 7.64 days and residual predictive deviation (RPD) of 1.8; for CT cage eggs, R2CV of 0.84, SECV of 5.38 days and RPD of 3.2; for CT free-range eggs, R2CV of 0.83, SECV of 5.52 days and RPD of 3.2; and for RT free-range eggs, R2CV of 0.82, SECV of 5.61 days, and RPD of 3.0. This study demonstrated that NIR spectroscopy can predict storage time non-destructively in intact egg samples. Even though the results of the present study are promising, further research is still needed to further extend these results to other production systems, as well as to explore the potential of this technique to predict other egg quality parameters associated with freshness.

9.
Energy Fuels ; 38(2): 1240-1257, 2024 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-38264623

RESUMO

Bio-oil produced from the pyrolysis of biomass is chemically complex, viscous, highly acidic, and highly oxygenated. Copyrolysis of biomass and plastics can enhance oil quality by raising the H/C ratio, leading to improved biofuel properties. In this work, copyrolysis of polystyrene and biomass was passed to a second-stage dielectric barrier discharge nonthermal plasma reactor with the aim to further improve the product bio-oil. Pyrolysis of the polystyrene and biomass produces volatiles that pass to the second stage to undergo cracking and autohydrogenation reactions under nonthermal plasma conditions. There was a synergistic interaction between biomass and polystyrene in terms of overall oil and gas yield and composition even in the absence of the nonthermal plasma. However, the introduction of the nonthermal plasma produced a marked increase in monocyclic aromatic hydrocarbons (e.g., ethylbenzene), whereas polycyclic aromatic compounds decreased in concentration. Most notably, the influence of the plasma markedly reduced the quantity of oxygenated compounds in the product oil. It is suggested that the unique reactive environment produced by the plasma involving high-energy electrons, excited radicals, ions, and intermediates increases the interaction of the polystyrene and biomass pyrolysis volatiles. Increasing input plasma power from 50 to 70 W further enhanced the effects of the nonthermal plasma.

10.
J Med Chem ; 67(2): 1008-1023, 2024 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-38170170

RESUMO

Pseudomonas aeruginosa is one of the top priority pathogens that requires immediate attention according to the World Health Organisation (WHO). Due to the alarming shortage of novel antimicrobials, targeting quorum sensing (QS), a bacterial cell to cell signaling system controlling virulence, has emerged as a promising approach as an antibiotic adjuvant therapy. Interference with the pqs system, one of three QS systems in P. aeruginosa, results in reduction of bacterial virulence gene expression and biofilm maturation. Herein, we report a hit to lead process to fine-tune the potency of our previously reported inhibitor 1 (IC50 3.2 µM in P. aeruginosa PAO1-L), which led to the discovery of 2-(4-(3-((6-chloro-1-isopropyl-1H-benzo[d]imidazol-2-yl)amino)-2-hydroxypropoxy)phenyl)acetonitrile (6f) as a potent PqsR antagonist. Compound 6f inhibited the PqsR-controlled PpqsA-lux transcriptional reporter fusion in P. aeruginosa at low submicromolar concentrations. Moreover, 6f showed improved efficacy against P. aeruginosa CF isolates with significant inhibition of pyocyanin, 2-alkyl-4(1H)-quinolones production.


Assuntos
Infecções por Pseudomonas , Quinolonas , Humanos , Infecções por Pseudomonas/tratamento farmacológico , Infecções por Pseudomonas/microbiologia , Percepção de Quorum , Biofilmes , Quinolonas/farmacologia , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Antibacterianos/metabolismo , Imidazóis/farmacologia , Imidazóis/uso terapêutico , Imidazóis/metabolismo , Pseudomonas aeruginosa/metabolismo , Proteínas de Bactérias , Fatores de Virulência
11.
Function (Oxf) ; 5(1): zqad070, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38223458

RESUMO

The BBSome, a complex of several Bardet-Biedl syndrome (BBS) proteins including BBS1, has emerged as a critical regulator of energy homeostasis. Although the BBSome is best known for its involvement in cilia trafficking, through a process that involve BBS3, it also regulates the localization of cell membrane receptors underlying metabolic regulation. Here, we show that inducible Bbs1 gene deletion selectively in proopiomelanocortin (POMC) neurons cause a gradual increase in body weight, which was associated with higher fat mass. In contrast, inducible deletion of Bbs3 gene in POMC neurons failed to affect body weight and adiposity. Interestingly, loss of BBS1 in POMC neurons led to glucose intolerance and insulin insensitivity, whereas BBS3 deficiency in these neurons is associated with slight impairment in glucose handling, but normal insulin sensitivity. BBS1 deficiency altered the plasma membrane localization of serotonin 5-HT2C receptor (5-HT2CR) and ciliary trafficking of neuropeptide Y2 receptor (NPY2R).In contrast, BBS3 deficiency, which disrupted the ciliary localization of the BBSome, did not interfere with plasma membrane expression of 5-HT2CR, but reduced the trafficking of NPY2R to cilia. We also show that deficiency in BBS1, but not BBS3, alters mitochondria dynamics and decreased total and phosphorylated levels of dynamin-like protein 1 (DRP1) protein. Importantly, rescuing DRP1 activity restored mitochondria dynamics and localization of 5-HT2CR and NPY2R in BBS1-deficient cells. The contrasting effects on energy and glucose homeostasis evoked by POMC neuron deletion of BBS1 versus BBS3 indicate that BBSome regulation of metabolism is not related to its ciliary function in these neurons.


Assuntos
Síndrome de Bardet-Biedl , Peso Corporal , Cílios , Pró-Opiomelanocortina , Humanos , Cílios/genética , Glucose/metabolismo , Proteínas Associadas aos Microtúbulos/genética , Neurônios/metabolismo , Pró-Opiomelanocortina/genética , Transporte Proteico/genética , Serotonina/metabolismo , Animais
13.
Anal Chem ; 95(49): 18287-18294, 2023 12 12.
Artigo em Inglês | MEDLINE | ID: mdl-38044628

RESUMO

Bacterial biofilms are structured communities consisting of cells enmeshed in a self-generated extracellular matrix usually attached to a surface. They contain diverse classes of molecules including polysaccharides, lipids, proteins, nucleic acids, and diverse small organic molecules (primary and secondary metabolites) which are organized to optimize survival and facilitate dispersal to new colonization sites. In situ characterization of the chemical composition and structure of bacterial biofilms is necessary to fully understand their development on surfaces relevant to biofouling in health, industry, and the environment. Biofilm development has been extensively studied using confocal microscopy using targeted fluorescent labels providing important insights into the architecture of biofilms. Recently, cryopreparation has been used to undertake targeted in situ chemical characterization using Orbitrap secondary ion mass spectrometry (OrbiSIMS), providing a label-free method for imaging biofilms in their native state. Although the high mass resolution of OrbiSIMS enables more confident peak assignments, it is still very challenging to assign most of the peaks in the spectra due to complexity of SIMS spectra and lack of automatic peak assignment methods. Here, we analyze the same OrbiSIMS depth profile data generated from the frozen-hydrated biofilm, but employ a new untargeted chemical filtering process utilizing mass spectral databases to assign secondary ions to decipher the large number of fragments present in the SIMS spectra. To move towards comprehensive analysis of different chemistries in the sample, we apply a molecular formula prediction approach which putatively assigns 81% of peaks in the 3D OrbiSIMS depth profile analysis. This enables us to catalog over 1000 lipids and their fragments, 3500 protein fragments, 71 quorum sensing-related molecules (2-alkyl-4-quinolones and N-acylhomoserine lactones), 150 polysaccharide fragments, and glycolipids simultaneously from one data set and map these separated molecular classes spatially through a Pseudomonas aeruginosa biofilm. Assignment of different chemistries in this sample facilitates identification of differences between biofilms grown on biofilm-promoting and biofilm-resistant polymers.


Assuntos
Biofilmes , Pseudomonas aeruginosa , Pseudomonas aeruginosa/química , Percepção de Quorum , Espectrometria de Massa de Íon Secundário/métodos , Glicolipídeos
14.
bioRxiv ; 2023 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-38045368

RESUMO

A novel group of biocidal compounds are the Crystal 3D (Cry) and Cytolytic (Cyt) proteins produced by Bacillus thuringiensis (Bt). Some Bt Cry proteins have a selective nematocidal activity, with Cry5B being the most studied. Cry5B kills nematode parasites by binding selectively to membrane glycosphingolipids, then forming pores in the cell membranes of the intestine leading to damage. Cry5B selectively targets multiple species of nematodes from different clades and has no effect against mammalian hosts. Levamisole is a cholinomimetic anthelmintic that acts by selectively opening L-subtype nicotinic acetylcholine receptor ion-channels (L-AChRs) that have been found on muscles of nematodes. A synergistic nematocidal interaction between levamisole and Cry5B has been described previously, but the location, mechanism and time-course of this synergism is not known. In this study we follow the timeline of the effects of levamisole and Cry5B on the Ca2+ levels in enterocyte cells from the intestine of Ascaris suum using fluorescence imaging. The peak Ca2+ responses to levamisole were observed after approximately 10 minutes while the peak responses to activated Cry5B were observed after approximately 80 minutes. When levamisole and Cry5B were applied simultaneously, we observed that the responses to Cry5B were bigger and occurred sooner than when it was applied by itself. It is proposed that there is an irreversible cytoplasmic Ca2+ overload that leads to necrotic cell-death in the enterocyte that is induced by levamisole opening Ca2+ permeable L-subtype nAChRs and the development of Ca2+ permeable Cry5B toxin pores in enterocyte plasma membranes. The effects of levamisole potentiate and speed the actions of Cry5B.

16.
Pulm Circ ; 13(4): e12317, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-38144948

RESUMO

This manuscript on real-world evidence (RWE) in pulmonary hypertension (PH) incorporates the broad experience of members of the Pulmonary Vascular Research Institute's Innovative Drug Development Initiative Real-World Evidence Working Group. We aim to strengthen the research community's understanding of RWE in PH to facilitate clinical research advances and ultimately improve patient care. Herein, we review real-world data (RWD) sources, discuss challenges and opportunities when using RWD sources to study PH populations, and identify resources needed to support the generation of meaningful RWE for the global PH community.

17.
Int J Mol Sci ; 24(21)2023 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-37958979

RESUMO

Bacterial contamination during space missions is problematic for human health and damages filters and other vital support systems. Staphylococcus aureus is both a human commensal and an opportunistic pathogen that colonizes human tissues and causes acute and chronic infections. Virulence and colonization factors are positively and negatively regulated, respectively, by bacterial cell-to-cell communication (quorum sensing) via the agr (accessory gene regulator) system. When cultured under low-shear modelled microgravity conditions (LSMMG), S. aureus has been reported to maintain a colonization rather than a pathogenic phenotype. Here, we show that the modulation of agr expression via reduced production of autoinducing peptide (AIP) signal molecules was responsible for this behavior. In an LSMMG environment, the S. aureus strains JE2 (methicillin-resistant) and SH1000 (methicillin-sensitive) both exhibited reduced cytotoxicity towards the human leukemia monocytic cell line (THP-1) and increased fibronectin binding. Using S. aureus agrP3::lux reporter gene fusions and mass spectrometry to quantify the AIP concentrations, the activation of agr, which depends on the binding of AIP to the transcriptional regulator AgrC, was delayed in the strains with an intact autoinducible agr system. This was because AIP production was reduced under these growth conditions compared with the ground controls. Under LSMMG, S. aureus agrP3::lux reporter strains that cannot produce endogenous AIPs still responded to exogenous AIPs. Provision of exogenous AIPs to S. aureus USA300 during microgravity culture restored the cytotoxicity of culture supernatants for the THP-1 cells. These data suggest that microgravity does not affect AgrC-AIP interactions but more likely the generation of AIPs.


Assuntos
Infecções Estafilocócicas , Ausência de Peso , Humanos , Fatores de Virulência/genética , Fatores de Virulência/metabolismo , Staphylococcus aureus/metabolismo , Proteínas Quinases/metabolismo , Percepção de Quorum/genética , Regulação para Baixo , Peptídeos/metabolismo , Proteínas de Bactérias/metabolismo
18.
mBio ; : e0203923, 2023 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-37843294

RESUMO

In its canonical interpretation, quorum sensing (QS) allows single cells in a bacterial population to synchronize gene expression and hence perform specific tasks collectively once the quorum cell density is reached. However, growing evidence in different bacterial species indicates that considerable cell-to-cell variation in the QS activation state occurs during growth, often resulting in coexisting subpopulations of cells in which QS is active (quorate cells) or inactive (non-quorate cells). Heterogeneity has been observed in the las QS system of the opportunistic pathogen Pseudomonas aeruginosa. However, the molecular mechanisms underlying this phenomenon have not yet been defined. The las QS system consists of an incoherent feedforward loop in which the LasR transcriptional regulator activates the expression of the lasI synthase gene and rsaL, coding for the lasI transcriptional repressor RsaL. Here, single-cell-level gene expression analyses performed in ad hoc engineered biosensor strains and deletion mutants revealed that direct binding of RsaL to the lasI promoter region increases heterogeneous activation of the las QS system. Experiments performed with a dual-fluorescence reporter system showed that the LasR-dependent expression of lasI and rsaL does not correlate in single cells, indicating that RsaL acts as a brake that stochastically limits the transition of non-quorate cells to the quorate state in a subpopulation of cells expressing high levels of this negative regulator. Interestingly, the rhl QS system that is not controlled by an analogous RsaL protein showed higher homogeneity with respect to the las system. IMPORTANCE Single-cell analyses can reveal that despite experiencing identical physico-chemical conditions, individual bacterial cells within a monoclonal population may exhibit variations in gene expression. Such phenotypic heterogeneity has been described for several aspects of bacterial physiology, including QS activation. This study demonstrates that the transition of non-quorate cells to the quorate state is a graded process that does not occur at a specific cell density and that subpopulations of non-quorate cells also persist at high cell density. Here, we provide a mechanistic explanation for this phenomenon, showing that a negative feedback regulatory loop integrated into the las system has a pivotal role in promoting cell-to-cell variation in the QS activation state and in limiting the transition of non-quorate cells to the quorate state in P. aeruginosa.

20.
Cureus ; 15(9): e45054, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37701164

RESUMO

The best overall measure of kidney function is glomerular filtration rate (GFR) as commonly estimated from serum creatinine concentrations (eGFRcr) using formulas that correct for the higher average creatinine concentrations in Blacks. After two decades of use, these formulas have come under scrutiny for estimating GFR differently in Blacks and non-Blacks. Discussions of whether to include race (Black vs. non-Black) in the calculation of eGFRcr fail to acknowledge that the original race-based eGFRcr provided the same CKD treatment recommendations for Blacks and non-Blacks based on directly (exogenously) measured GFR. Nevertheless, the National Kidney Foundation and the American Society of Nephrology Task Force on Reassessing the Inclusion of Race in Diagnosing Kidney Disease removed race in CKD treatment guidelines and pushed for the immediate adoption of a race-free eGFRcr formula by physicians and clinical laboratories. This formula is projected to negate CKD in 5.51 million White and other non-Black adults and reclassify CKD to less severe stages in another 4.59 million non-Blacks, in order to expand treatment eligibility to 434,000 Blacks not previously diagnosed and to 584,000 Blacks previously diagnosed with less severe CKD. This review examines: 1) the validity of the arguments for removing the original race correction, and 2) the performance of the proposed replacement formula. Excluding race in the derivation of eGFRcr changed the statistical bias from +3.7 to -3.6 ml/min/1.73m2 in Blacks and from +0.5 to +3.9 in non-Blacks, i.e., promoting CKD diagnosis in Blacks at the cost of restricting diagnosis in non-Blacks. By doing so, the revised eGFRcr greatly exaggerates the purported racial disparity in CKD burden. Claims that the revised formulas identify heretofore undiagnosed CKD in Blacks are not supported when studies that used kidney failure replacement therapy and mortality are interpreted as proxies for baseline CKD. Alternatively, a race-stratified eGFRcr (i.e., separate equations for Blacks and non-Blacks) would provide the least biased eGFRcr for both Blacks and non-Blacks and the best medical treatment for all patients.

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