Highly parallelized laboratory evolution of wine yeasts for enhanced metabolic phenotypes.

Adaptive Laboratory Evolution (ALE) of microorganisms can improve the efficiency of sustainable industrial processes important to the global economy. However, stochasticity and genetic background effects often lead to suboptimal outcomes during laboratory evolution. Here we report an ALE platform to circumvent these shortcomings through parallelized clonal evolution at an unprecedented scale. Using this platform, we evolved 104 yeast populations in parallel from many strains for eight desired wine fermentation-related traits. Expansions of both ALE replicates and lineage numbers broadened the evolutionary search spectrum leading to improved wine yeasts unencumbered by unwanted side effects. At the genomic level, evolutionary gains in metabolic characteristics often coincided with distinct chromosome amplifications and the emergence of side-effect syndromes that were characteristic of each selection niche. Several high-performing ALE strains exhibited desired wine fermentation kinetics when tested in larger liquid cultures, supporting their suitability for application. More broadly, our high-throughput ALE platform opens opportunities for rapid optimization of microbes which otherwise could take many years to accomplish.

Doppler Ultrasound and Resistive Indices in the Diagnosis of Ureteropelvic Junction Obstruction in the Pediatric Population.

OBJECTIVES: Mercapto acetyl tri-glycine renogram (MAG3) scan has been the gold standard assessment of pediatric ureteropelvic junction obstruction (UPJO) but requires intravenous access and radiation exposure. While Doppler ultrasound measurements of resistive indices (RI) of the arcuate arteries have been proposed as an alternative assessment of obstruction, they have not been widely adopted in the pediatric population. We hypothesized that RI of the main renal artery (RA) is more strongly correlated with MAG3 findings than arcuate RI. METHODS: Pediatric patients with unilateral Society for Fetal Urology grade 3-4 hydronephrosis undergoing concomitant RUS and MAG3 were recruited. Doppler ultrasound peak systolic velocity (PSV); RI of bilateral RA at the origin, middle, and hilum; and RI of the superior, middle, and lower pole arcuate arteries were obtained. MAG3 differential renal function (DRF) and T½ were recorded. Differences in RI measurements (DRI) between the affected and normal kidney were calculated and compared with DRF and T½. RESULTS: 31 patients (median 4.6-month-old) were enrolled. Only RA RI at the origin differed between affected and normal kidneys (p < .001). DRI RA at the origin showed weak evidence for an association with MAG3 DRF < 40% (p .07). DRI was not associated with T½ > 20 minutes. CONCLUSION: There was weak evidence for an association between RA DRI at the origin and DRF but not with T½. These findings suggest that RA DRI may provide additional data in the evaluation of patients with UPJO to tailor the use of MAG3 and associated risk of radiation exposure to those patients most at risk for concomitant renal function impairment.

Predictive evolution of metabolic phenotypes using model-designed environments.

Adaptive evolution under controlled laboratory conditions has been highly effective in selecting organisms with beneficial phenotypes such as stress tolerance. The evolution route is particularly attractive when the organisms are either difficult to engineer or the genetic basis of the phenotype is complex. However, many desired traits, like metabolite secretion, have been inaccessible to adaptive selection due to their trade-off with cell growth. Here, we utilize genome-scale metabolic models to design nutrient environments for selecting lineages with enhanced metabolite secretion. To overcome the growth-secretion trade-off, we identify environments wherein growth becomes correlated with a secondary trait termed tacking trait. The latter is selected to be coupled with the desired trait in the application environment where the trait manifestation is required. Thus, adaptive evolution in the model-designed selection environment and subsequent return to the application environment is predicted to enhance the desired trait. We experimentally validate this strategy by evolving Saccharomyces cerevisiae for increased secretion of aroma compounds, and confirm the predicted flux-rerouting using genomic, transcriptomic, and proteomic analyses. Overall, model-designed selection environments open new opportunities for predictive evolution.

A prospective survey study of lower urinary tract dysfunction in childhood cancer survivors after vincristine and/or doxorubicin chemotherapy.

BACKGROUND: Two chemotherapeutic agents used widely in pediatric oncology are vincristine (VCR) and doxorubicin (DOX), which may cause neuropathy and myopathy, respectively. The study hypothesis is that neurotoxic effects of VCR and/or myotoxic effects of DOX affect bladder physiology and manifest clinically as lower urinary tract dysfunction (LUTD). PROCEDURE: Based on a priori power analysis, 161 children divided evenly by gender were recruited. Children aged 5-10 years completed the dysfunctional voiding scoring system (DVSS) survey. The study cohort comprised cancer survivors treated with VCR and/or DOX. Healthy controls were recruited from well-child clinic visits. Exclusion criteria included pelvic-based malignancy, pelvic irradiation, pre-existing LUTD, neurologic abnormalities, and treatment with cyclophosphamide/ifosfamide. DVSS scores and presence of LUTD, defined as DVSS scores above gender-specific thresholds (males ≥9, females ≥6), were compared across cohorts. RESULTS: Median DVSS scores were higher in the study cohort (6 vs. 4, p = .003). Moreover, children in the study cohort were more likely to exceed threshold scores for LUTD (38.8% vs. 21%, p = .014; OR 1.8). Subanalysis by gender revealed female cancer survivors are more likely to report LUTD than controls (57.5% vs. 30%, p = .013, OR 1.9). This did not hold true for males (20% vs. 12.2%, p = .339). CONCLUSIONS: Childhood cancer survivors who received VCR and/or DOX reported higher rates of LUTD than controls. Female cancer survivors appear more likely to suffer from LUTD than males. Further study with a positive control cohort of cancer survivors who received non-VCR, non-DOX chemotherapy is underway to elucidate the contribution of a cancer diagnosis to LUTD.

Genetic and transcriptomic evidences suggest ARO10 genes are involved in benzenoid biosynthesis by yeast.

Benzenoids are compounds associated with floral and fruity flavours in flowers, fruits and leaves and present a role in hormonal signalling in plants. These molecules are produced by the phenyl ammonia lyase pathway. However, some yeasts can also synthesize them from aromatic amino acids using an alternative pathway that remains unknown. Hanseniaspora vineae can produce benzenoids at levels up to two orders of magnitude higher than Saccharomyces species, so it is a model microorganism for studying benzenoid biosynthesis pathways in yeast. According to their genomes, several enzymes have been proposed to be involved in a mandelate pathway similar to that described for some prokaryotic cells. Among them, the ARO10 gene product could present benzoylformate decarboxylase activity. This enzyme catalyses the decarboxylation of benzoylformate into benzaldehyde at the end of the mandelate pathway in benzyl alcohol formation. Two homologous genes of ARO10 were found in the two sequenced H. vineae strains. In this study, nine other H. vineae strains were analysed to detect the presence and per cent homology of ARO10 sequences by PCR using specific primers designed for this species. Also, the copy number of the genes was estimated by quantitative PCR. To verify the relation of ARO10 with the production of benzyl alcohol during fermentation, a deletion mutant in the ARO10 gene of Saccharomyces cerevisiae was used. The two HvARO10 paralogues were analysed and compared with other α-ketoacid decarboxylases at the sequence and structural level.

Melatonin and glycolytic protein interactions are related to yeast fermentative capacity.

Melatonin is an indole amine that interacts with some proteins in mammals, such as calreticulin, calmodulin or sirtuins. In yeast, melatonin is synthetized and interacts with glycolytic proteins during alcoholic fermentation in Saccharomyces cerevisiae. Due to its importance as an antioxidant molecule in both Saccharomyces and non-Saccharomyces yeasts, the aim of this study was to determine the intracellular and extracellular synthesis profiles of melatonin in four non-Saccharomyces strains (Torulaspora delbrueckii, Hanseniaspora uvarum, Starmeralla bacillaris and Metschnikowia pulcherrima) and to confirm whether glycolytic enzymes can also interact with this molecule in non-conventional yeast cells. Melatonin from fermentation samples was analyzed by liquid chromatography mass spectrometry, and proteins bound to melatonin were immunopurified by melatonin-IgG-Dynabeads. Melatonin was produced in a similar pattern in all non-Saccharomyces yeast, with M. pulcherrima and S. bacillaris being the highest producers. However, melatonin only bound to proteins in two non-conventional yeasts, S. bacillaris and T. delbrueckii, which specifically had higher fermentative capacities. Sequence analysis showed that most proteins shared high levels of homology with glycolytic enzymes, but an RNA-binding protein, the elongation alpha factor, which is related to mitochondria, was also identified. This study reports for the first time the interaction of melatonin with proteins inside non-Saccharomyces yeast cells. These results reinforce the possible role of melatonin as a signal molecule, likely related to fermentation metabolism and provide a new perspective for understanding its role in yeast.

Harnessing yeast metabolism of aromatic amino acids for fermented beverage bioflavouring and bioproduction.

Aromatic amino acid metabolism in yeast is an important source of secondary compounds that influence the aroma and flavour of alcoholic beverages and foods. Examples are the higher alcohol 2-phenylethanol, and its acetate ester, 2-phenylethyl acetate, which impart desirable floral aromas in wine, beer and baker's products. Beyond this well-known influence on the organoleptic properties of alcoholic beverages and foods, there is a growing interest in understanding and modulating yeast aromatic amino acid metabolism. The tryptophan derivatives melatonin and serotonin have bioactive properties and exert positive effects on human health, and aromatic amino acids are also the precursors of products of industrial interest, such as nutraceuticals, fragrances, and opium-derived drugs. This mini-review presents current knowledge on the formation of compounds from aromatic amino acids by Saccharomyces cerevisiae, from genetic and environmental influences on their flavour impacts in alcoholic beverages to their potential as bioactive compounds, and the use of yeast as microbial factories for the production of commercially relevant aromatic compounds.

The role of the membrane lipid composition in the oxidative stress tolerance of different wine yeasts.

Oxidative stress is a common stress in yeasts during the stages of the winemaking process in which aerobic growth occurs, and it can modify the cellular lipid composition. The aim of this study was to evaluate the oxidative stress tolerance of two non-conventional yeasts (Torulaspora delbrueckii and Metschnikowia pulcherrima) compared to Saccharomyces cerevisiae. Therefore, their resistance against H2O2, the ROS production and the cellular lipid composition were assessed. The results showed that the non-Saccharomyces yeasts used in this study exhibited higher resistance to H2O2 stress and lower ROS accumulation than Saccharomyces. Regarding the cellular lipid composition, the two non-Saccharomyces species studied here displayed a high percentage of polyunsaturated fatty acids, which resulted in more fluid membranes. This result could indicate that these yeasts have been evolutionarily adapted to have better resistance against the oxidative stress. Furthermore, under external oxidative stress, non-Saccharomyces yeasts were better able to adapt their lipid composition as a defense mechanism by decreasing their percentage of polyunsaturated fatty acids and squalene and increasing their monounsaturated fatty acids.

The production of aromatic alcohols in non-Saccharomyces wine yeast is modulated by nutrient availability.

Aromatic alcohols (tryptophol, phenylethanol, tyrosol) positively contribute to organoleptic characteristics of wines, and are also described as bioactive compounds and quorum sensing molecules. These alcohols are produced by yeast during alcoholic fermentation via the Erhlich pathway, although in non-Saccharomyces this production has been poorly studied. We studied how different wine yeast species modulate the synthesis patterns of aromatic alcohol production depending on glucose, nitrogen and aromatic amino acid availability. Nitrogen limitation strongly promoted the production of aromatic alcohols in all strains, whereas low glucose generally inhibited it. Increased aromatic amino acid concentrations stimulated the production of aromatic alcohols in all of the strains and conditions tested. Thus, there was a clear association between the nutrient conditions and production of aromatic alcohols in most of the wine yeast species analysed. Additionally, the synthesis pattern of these alcohols has been evaluated for the first time in Torulaspora delbrueckii, Metschnikowia pulcherrima and Starmellera bacillaris.

Concerted evolution of life stage performances signals recent selection on yeast nitrogen use.

Exposing natural selection driving phenotypic and genotypic adaptive differentiation is an extraordinary challenge. Given that an organism's life stages are exposed to the same environmental variations, we reasoned that fitness components, such as the lag, rate, and efficiency of growth, directly reflecting performance in these life stages, should often be selected in concert. We therefore conjectured that correlations between fitness components over natural isolates, in a particular environmental context, would constitute a robust signal of recent selection. Critically, this test for selection requires fitness components to be determined by different genetic loci. To explore our conjecture, we exhaustively evaluated the lag, rate, and efficiency of asexual population growth of natural isolates of the model yeast Saccharomyces cerevisiae in a large variety of nitrogen-limited environments. Overall, fitness components were well correlated under nitrogen restriction. Yeast isolates were further crossed in all pairwise combinations and coinheritance of each fitness component and genetic markers were traced. Trait variations tended to map to quantitative trait loci (QTL) that were private to a single fitness component. We further traced QTLs down to single-nucleotide resolution and uncovered loss-of-function mutations in RIM15, PUT4, DAL1, and DAL4 as the genetic basis for nitrogen source use variations. Effects of SNPs were unique for a single fitness component, strongly arguing against pleiotropy between lag, rate, and efficiency of reproduction under nitrogen restriction. The strong correlations between life stage performances that cannot be explained by pleiotropy compellingly support adaptive differentiation of yeast nitrogen source use and suggest a generic approach for detecting selection.

Replenishment and mobilization of intracellular nitrogen pools decouples wine yeast nitrogen uptake from growth.

Wine yeast capacity to take up nitrogen from the environment and catabolize it to support population growth, fermentation, and aroma production is critical to wine production. Under nitrogen restriction, yeast nitrogen uptake is believed to be intimately coupled to reproduction with nitrogen catabolite repression (NCR) suggested mediating this link. We provide a time- and strain-resolved view of nitrogen uptake, population growth, and NCR activity in wine yeasts. Nitrogen uptake was found to be decoupled from growth due to early assimilated nitrogen being used to replenish intracellular nitrogen pools rather than being channeled directly into reproduction. Internally accumulated nitrogen was later mobilized to support substantial population expansion after external nitrogen was depleted. On good nitrogen sources, the decoupling between nitrogen uptake and growth correlated well with relaxation of NCR repression, raising the potential that the latter may be triggered by intracellular build-up of nitrogen. No link between NCR activity and nitrogen assimilation or growth on poor nitrogen sources was found. The decoupling between nitrogen uptake and growth and its influence on NCR activity is of relevance for both wine production and our general understanding of nitrogen use.

Contribution of yeast and base wine supplementation to sparkling wine composition.

BACKGROUND: The differential characteristic of sparkling wine is the formation of foam, which is dependent, among other factors, on yeast autolysis, aging and oenological practices. In this study, we analyzed the effects of yeast strain, nutrient supplementation to the base wine and aging process on the sparkling wine composition and its foamability. RESULTS: We determined that the addition of inorganic nitrogen promoted nitrogen liberation to the extracellular medium, while the addition of inactive dry yeast to the base wine caused an increase in the polysaccharide concentration and foaming properties of the sparkling wine. The use of synthetic and natural base wines allowed us to discriminate that the differences in high-molecular-weight polysaccharides and oligosaccharides could be attributed to the yeast cells and that the higher nitrogen content in the natural wine could be due to external proteolysis. CONCLUSION: The practices of nitrogen addition and supplementation of inactive dry yeast could modulate the main characteristics of the sparkling wine and be a critical element for the design of this kind of wine. © 2016 Society of Chemical Industry.

Biomarkers for detecting nitrogen deficiency during alcoholic fermentation in different commercial wine yeast strains.

Nitrogen deficiencies in grape musts are one of the main causes of stuck or sluggish wine fermentations. Several putative biomarkers were tested in order to analyze their appropriateness to detect nitrogen stress in the yeast. To this aim, four commercial wine strains (PDM, ARM, RVA and TTA) were grown in a synthetic grape must with different nitrogen concentrations. Trehalose accumulation, arginase activity and the expression of eleven genes were tested in these wine strains, known to have different nitrogen requirements. The overall response of the four strains was similar, with differences in response intensity (PDM and RVA with higher intensity) and response time (which was also related with nitrogen consumption time). Trehalose response was mostly related to entry into the stationary phase, whereas arginase activity was responsive to nitrogen depletion, although its measurement is too complicated to be used for routine monitoring during winemaking. The expression of the genes DAL4, DAL5, DUR3 and GAP1 was clearly related to nitrogen depletion and thus, GAP1 and DAL4 were selected as markers of nitrogen deficiency. In order to adapt expression analysis to winemaking conditions, the original strains were transformed into reporter strains based on the expression of green fluorescent protein (GFP) under control of the promoters for GAP1 and DAL4. The transformants had a similar fermentative capacity to the parental strains and were able to detect alterations in yeast physiological status due to nitrogen limitations.

Biomass production and alcoholic fermentation performance of Saccharomyces cerevisiae as a function of nitrogen source.

Nitrogen limitation is one of the most common causes for stuck or sluggish fermentation. A broad range of values have been reported as the minimum nitrogen concentration necessary for the completion of alcoholic fermentation. We have analyzed the minimum nitrogen concentration required to yield the maximum biomass (nitrogen reference value) using a microwell plate reader to monitor fermentation with different nitrogen sources and sugar concentrations. The biomass yield was dependent on the amount of available nitrogen, the nature of nitrogen source, and the sugar concentration in the medium. Nevertheless, achieving the maximum biomass was not sufficient to ensure the completion of the alcoholic fermentation, because the fermentation of 280 g sugar L(-1) stuck, regardless of the nature and concentration of nitrogen source. However, a mixture of five amino acids (Leu, Ile, Val, Phe and Thr) as the nitrogen source allowed for maximum sugar consumption. Analysis of cell vitality by impedance showed a significant improvement in the vitality for cells fermenting using this amino acid combination.

Nitrogen requirements of commercial wine yeast strains during fermentation of a synthetic grape must.

Nitrogen deficiencies in grape musts are one of the main causes of stuck or sluggish wine fermentations. Currently, the most common method for dealing with nitrogen-deficient fermentations is adding supplementary nitrogen (usually ammonium phosphate). However, it is important to know the specific nitrogen requirement of each strain, to avoid excessive addition that can lead to microbial instability and ethyl carbamate accumulation. In this study, we aimed to determine the effect of increasing nitrogen concentrations of three different nitrogen sources on growth and fermentation performance in four industrial wine yeast strains. This task was carried out using statistical modeling techniques. The strains PDM and RVA showed higher growth-rate and maximum population size and consumed nitrogen much more quickly than strains ARM and TTA. Likewise, the strains PDM and RVA were also the greatest nitrogen demanders. Thus, we can conclude that these differences in nitrogen demand positively correlated with higher growth rate and higher nitrogen uptake rate. The most direct effect of employing an adequate nitrogen concentration is the increase in biomass, which involves a higher fermentation rate. However, the impact of nitrogen on fermentation rate is not exclusively due to the increase in biomass because the strain TTA, which showed the worst growth behavior, had the best fermentation activity. Some strains may adapt a strategy whereby fewer cells with higher metabolic activity are produced. Regarding the nitrogen source used, all the strains showed the better and worse fermentation performance with arginine and ammonium, respectively.

Importance of micronutrients and organic nitrogen in fermentations with Torulaspora delbrueckii and Saccharomyces cerevisiae.

The current use of non-Saccharomyces yeasts in mixed fermentations increases the relevance of the interactions between yeast species. In this work, the interactions between Saccharomyces cerevisiae and Torulaspora delbrueckii were analyzed. For this purpose, fermentations with and without contact between strains of those yeast species were performed in synthetic must. Fermentation kinetics, yeast growth and dynamics were measured over time. Additionally, the effects of nitrogen and other nutrient supplementations on the mixed fermentations were determined. Our results showed that S. cerevisiae did not always dominate the sequential fermentations, and experiments without yeast contact (in which T. delbrueckii cells were removed from the medium before inoculating S. cerevisiae at 48 h) resulted in stuck fermentations except when the inoculum size was increased (from 2 × 106 to 108 cells/mL) or there was a supplementation of thiamine, zinc and amino acids at the same concentration as initially found in the synthetic must. Our findings highlight the importance of inoculum size and ensuring the availability of enough micronutrients for all yeast species, especially in sequential fermentations.

Unexpected challenges faced by caregivers of children with neurogenic bladder: A qualitative study.

BACKGROUND: Management of the neurogenic bladder is variable, complex, and often requires a demanding bladder care regimen which may present caregiver burdens that are unique among chronic disease. While research into patient quality of life is increasing, parallel study of the caregiver experience is scant. Existing research primarily comprises survey data using validated instruments originally developed for non-urologic conditions, such as dementia. These surveys may detect high caregiver burden and decreased quality of life amongst caregivers but are limited in their ability to understand the underlying causes. OBJECTIVE: To characterize the experience of those caring for children with neurogenic bladders, with a focus on unexpected burdens and challenges. METHODS: In light of limited existing research, a qualitative research methodology was selected to explore the caregiver experience. Semi-structured phone interviews were conducted with primary caregivers of children with neurogenic bladder, all of whom were patients in the pediatric urology department of a single tertiary pediatric referral center. Purposive sampling was used to ensure diverse representation. Interviews were recorded, transcribed, and professionally translated if needed. Transcripts were analyzed using a team-based inductive grounded-theory approach, facilitated by ATLAS. ti software. Member-checking focus groups were held to validate the results. RESULTS: Twenty-five caregivers were interviewed (20 in English, 5 in Spanish), at which point thematic saturation was reached. Three primary themes emerged surrounding the topic of unexpected challenges: 1. High caregiver burden, 2. Challenges with catheterization and supplies, 3. Urinary tract infections. Member-checking focus groups validated the thematic analysis and provided additional insights into mitigating factors for these challenges. A child's independence with his or her health care regimen was cited as particularly important for decreasing caregiver burden. DISCUSSION: Caregivers of children with neurogenic bladder report their role is more difficult than they anticipated it would be. Catheterization represents a particularly burdensome task, and recurrent infections are an unexpected and persistent medical challenge. Understanding unexpected challenges that caregivers face will help pediatric urologists target modifiable factors to decrease caregiver burden, address current gaps in counseling and expectation-setting, and set the stage for more complete shared decision-making. CONCLUSIONS: This study represents an initial qualitative characterization of the experience caring for a child with neurogenic bladder. This is a key first step in understanding how caregivers make decisions for their children and their families. This initial study is foundational to a larger project to create a decision aid for caregivers of children with neurogenic bladder.

Feasibility of establishing a multi-center research database using the electronic health record: The PURSUIT network.

BACKGROUND: Although multi-center research is needed in pediatric urology, collaboration is impeded by differences in physician documentation and research resources. Electronic health record (EHR) tools offer a promising avenue to overcome these barriers. OBJECTIVE: To assess the accuracy, completeness, and utilization of structured data elements across multiple practices. STUDY DESIGN: A standardized template was developed and implemented at five academic pediatric urology practices to document clinic visits for patients with congenital hydronephrosis and/or vesicoureteral reflux. Data from standardized elements in the template and from pre-existing EHR fields were extracted into a secure database. A 20% random sample of infants with data from structured elements from 1/1/2020 and 4/30/2021 were identified and compared to manual chart review at sites with >100 charts; all other sites reviewed at least 20 charts. Manual chart review was standardized across sites and included: clinic and operative notes, orders linked to the clinic encounter, radiology results, and active medications. Accuracy of data extraction was evaluated by computing the kappa statistic and percentage agreement. For sites that had adopted the templates prior to 6/1/2019 (early adopters), a list of eligible patients with an initial clinic visit from 1/1/2020-7/27/2020 was generated using standardized reporting techniques and confirmed by manual chart review. Physician utilization of the template was then calculated by comparing patients with data obtained from the note template to the generated list of eligible patients. RESULTS: 230 patient records met study criteria. Agreement between manual chart review and data extracted from the EHR was high (>85%). Race, ethnicity and insurance data were misclassified in about 10-15% of cases; this was due to site-specific differences in how these fields were coded. Renal ultrasound was misclassified 12% of the time; this was primarily due to outside images documented in radiology results but not included in the clinical note. All other data elements had >90% agreement (Figure). Template utilization for early adopters was >75% (75.5-87.5%). DISCUSSION: This is the first study in urology to demonstrate that use of structured data elements can support multi-center research. Limitations include: inclusion of only academic sites with the Epic EHR and lack of data on utilization and sustainability at sites without a prior history of structured template use. CONCLUSIONS: Multi-center research collaboration using EHR-based data collection tools is feasible with generally high accuracy compared to manual chart review. Additionally, sites with a long history of template adoption have high levels of provider utilization.

Pyeloplasty with ureteral stent placement in children: Do prophylactic antibiotics serve a purpose?

OBJECTIVES: Ureteral stents are commonly used during pyeloplasty to ensure drainage and anastomotic healing. Antibiotic prophylaxis is often used due to concerns for urinary tract infection (UTI). Although many surgeons prescribe prophylactic antibiotics following pyeloplasty, practices vary widely due to lack of clear evidence-based guidelines. We hypothesize that the rate of stent UTI does not significantly vary between children who receive antibiotics and those who do not. METHODS: We reviewed the medical records of 741 patients undergoing pyeloplasty between January 2010 and July 2018 across seven institutions. Exclusion criteria were: age older than 22 years, no stent placed, externalized stents used, and incomplete records. Surgical approach, age, antibiotic use, stent duration, Foley duration, and urine culture results were recorded. Patients were categorized into two groups, those younger than four years of age and those four years and older as proxy for likely diaper use. Univariate logistic regression was conducted to identify variables associated with UTI. Multivariable backward stepwise logistic regression was used to identify the best model with Akaike information criterion as model selection criteria. The selected model was used to calculate odds ratios and 95% confidence intervals summarizing the association between prophylactic antibiotics and stent UTI while controlling for age, gender, and intra-operative urine cultures. RESULTS: 672 patients were included; 338 received antibiotic prophylaxis and 334 did not. These groups differed in mean age (3.91 vs. 6.91 years, P < .001), mean stent duration (38.5 vs. 35.32 days, P < .001), and surgical approach (53.25% vs. 32.04% open vs. laparoscopic, P < .001). The incidence of stent UTI was low overall (7.59%) and similar in both groups: 31/338 (9.17%) in the prophylaxis group and 20/334 (5.99%) in the non-prophylaxis group (P = .119). Although female gender, likely diaper use, and positive intra-operative urine culture were each associated with significantly higher odds of stent UTI, prophylactic antibiotic use was not associated with significant reduction in stent UTI in any of these groups. Surgical approach, stent duration, and Foley duration were not associated with stent UTI. CONCLUSION: Incidence of stent UTI is low overall following pyeloplasty. Prophylactic antibiotics are not associated with lower rates of stent UTI following pyeloplasty even after controlling for risk factors of female gender, likely diaper use, and positive intra-operative urine culture. Routine administration of prophylactic antibiotics after pyeloplasty does not appear to be beneficial, and may be best reserved for those with multiple risk factors for UTI.

Protective Effects of Melatonin on Saccharomyces cerevisiae under Ethanol Stress.

During alcoholic fermentation, Saccharomyces cerevisiae is subjected to several stresses, among which ethanol is of capital importance. Melatonin, a bioactive molecule synthesized by yeast during alcoholic fermentation, has an antioxidant role and is proposed to contribute to counteracting fermentation-associated stresses. The aim of this study was to unravel the protective effect of melatonin on yeast cells subjected to ethanol stress. For that purpose, the effect of ethanol concentrations (6 to 12%) on a wine strain and a lab strain of S. cerevisiae was evaluated, monitoring the viability, growth capacity, mortality, and several indicators of oxidative stress over time, such as reactive oxygen species (ROS) accumulation, lipid peroxidation, and the activity of catalase and superoxide dismutase enzymes. In general, ethanol exposure reduced the cell growth of S. cerevisiae and increased mortality, ROS accumulation, lipid peroxidation and antioxidant enzyme activity. Melatonin supplementation softened the effect of ethanol, enhancing cell growth and decreasing oxidative damage by lowering ROS accumulation, lipid peroxidation, and antioxidant enzyme activities. However, the effects of melatonin were dependent on strain, melatonin concentration, and growth phase. The results of this study indicate that melatonin has a protective role against mild ethanol stress, mainly by reducing the oxidative stress triggered by this alcohol.