Showing papers on "Incubation published in 2021"

The incubation period during the pandemic of COVID-19: a systematic review and meta-analysis.

Abstract: The aim of our study was to determine through a systematic review and meta-analysis the incubation period of COVID-19. It was conducted based on the preferred reporting items for systematic reviews and meta-analyses (PRISMA). Criteria for eligibility were all published population-based primary literature in PubMed interface and the Science Direct, dealing with incubation period of COVID-19, written in English, since December 2019 to December 2020. We estimated the mean of the incubation period using meta-analysis, taking into account between-study heterogeneity, and the analysis with moderator variables. This review included 42 studies done predominantly in China. The mean and median incubation period were of maximum 8 days and 12 days respectively. In various parametric models, the 95th percentiles were in the range 10.3–16 days. The highest 99th percentile would be as long as 20.4 days. Out of the 10 included studies in the meta-analysis, 8 were conducted in China, 1 in Singapore, and 1 in Argentina. The pooled mean incubation period was 6.2 (95% CI 5.4, 7.0) days. The heterogeneity (I2 77.1%; p < 0.001) was decreased when we included the study quality and the method of calculation used as moderator variables (I2 0%). The mean incubation period ranged from 5.2 (95% CI 4.4 to 5.9) to 6.65 days (95% CI 6.0 to 7.2). This work provides additional evidence of incubation period for COVID-19 and showed that it is prudent not to dismiss the possibility of incubation periods up to 14 days at this stage of the epidemic.

Responses of soil WEOM quantity and quality to freeze–thaw and litter manipulation with contrasting soil water content: A laboratory experiment

Abstract: Future climatic change is likely to increase the occurrence of soil freeze–thaw (FT) events in high latitude and/or high altitude zones, which can substantially influence the dynamics of dissolved organic matter (DOM) released into the soils. However, it is not clear how the quantity and quality of soil DOM respond to changing FT patterns under different soil moisture and litter manipulation conditions in northern temperate forest stands. In this study, litter-amended and non-amended forest soils were incubated for 360 days at three soil moisture levels (30%, 60%, and 90% water-filled pore space) and three intensities of FT disturbance (low, high, and none). We quantified heterotrophic respiration, enzyme activity, microbial biomass, and water-extractable organic matter (WEOM) as a proxy for DOM in soils during the incubation experiment. The quality of WEOM was characterized by biodegradability, UV absorbance and parallel factor analysis modelling of fluorescence excitation emission matrices. Concentrations of water-extractable organic carbon (WEOC) and biodegradable WEOC declined continuously in all treatments over the 360-day incubation period. The dominant component of fluorescent WEOM shifted from humic- and fulvic- like components during the first 108 days of incubation, to protein-like components of microbial origin, characterized by high aromaticity, at the end of the incubation period. Litter amendment, FT disturbance, and their interaction increased WEOC concentrations in soils during the early 108-day incubation period, particularly in soils with low moisture and high FT intensity, but these increases disappeared after 252 days incubation at 15 °C. Litter-derived fluorescent WEOM in soils without FT disturbance was dominated by protein-like components after 14 days of incubation, but these were replaced by humic- and fulvic-like components after 108 days. This replacement effect was weaker in soils with FT disturbance, which we attribute to changes in microbial properties, including enzyme activity, microbial biomass and activity.

Evaluation of Optimal Blood Culture Incubation Time To Maximize Clinically Relevant Results from a Contemporary Blood Culture Instrument and Media System.

Abstract: Timely diagnosis of microorganisms in blood cultures is necessary to optimize therapy. Although blood culture media and systems have evolved for decades, the standard interval for incubation prior to being discarded as negative has remained 5 days. Here, we evaluated the optimal incubation time for the BacT/Alert Virtuo blood culture detection system (bioMerieux) using FA Plus (aerobic) and FN Plus (anaerobic) resin culture bottles in routine clinical use. Following institutional review board (IRB) approval, a retrospective review evaluated the outcomes of 158,710 bottles collected between November 2018 and October 2019. The number of positive blood bottles was 13,592 (8.6%); 99% of positive aerobic and anaerobic bottles flagged positive by 91.5 and 108 h, respectively. The mean (median) times to positivity were 18.4 h (15.6 h) for Staphylococcus aureus, 12.3 h (9.5 h) for Escherichia coli, 22.2 h (15.9 h) for Pseudomonas aeruginosa, and 48.9 h (42.9 h) for Candida spp. Only 175 bottles (0.1% of all bottles) flagged positive after 4 days of incubation; 89 (51%) of these bottles grew Cutibacterium (Propionibacterium) species. Chart review of blood cultures positive after 4 days (96 h) rarely had a clinical impact and sometimes had a negative impact on patient care. Finally, a seeded study of the HACEK group (i.e., Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, and Kingella), historically associated with delayed blood culture positivity, demonstrated no benefit to extended incubation beyond 4 days. Collectively, these findings demonstrated that a 4-day incubation time was sufficient for the Virtuo system and media. Implementation of the 4-day incubation time could enhance clinically relevant results by reducing recovery of contaminants and finalizing blood cultures 1 day earlier.

Effects of the novel HPPD-inhibitor herbicide QYM201 on enzyme activity and microorganisms, and its degradation in soil.

Abstract: QYM201 is a 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibiting herbicide recently registered in China for controlling grass and broadleaf weeds in wheat. It is a novel herbicide, and its potential harm to soil ecosystems has not yet been reported. This study investigates the influence of QYM201 on soil enzyme activity and microorganism quantities in two different soils at concentrations of 0.1, 1, and 5 mg kg−1 soil. Results indicate that QYM201 initially inhibited soil protease, urease, and sucrase activity and this effect increased with concentration. During the later stages of incubation, inhibitory effects gradually weakened and by the end of the experiment (45 days), enzyme activity was restored to control levels. Catalase activity was stimulated by QYM201, with significant differences observed between the QYM201-treated groups and the control at the onset of exposure. This stimulation effect decreased during the later stages of the experiment. However, catalase activity was still significantly higher at the end of the experiment compared to the control. The effects of QYM201 on soil microorganisms differed. Initially, bacteria and actinomycetes quantities were decreased by QYM201 (10 days). As the incubation progressed, microorganism quantities in the lower concentration groups (0.1 and 1 mg kg−1 soil) were restored to control levels, while those of the high concentration group (5 mg kg−1 soil) did not fully recover. QYM201 did not significantly impact the quantity of fungi. The half-life and degradation rate constant (k) of QYM201 for the two studied soil types were 23.1 days and 16.1 days, and 0.030 and 0.043 day−1, respectively.

Developmental events and cellular changes occurred during esophageal development of quail embryos.

Abstract: The current study focused on the histogenesis of the esophagus in quail embryos. Formation of the gut tube occurred on the 4th day of incubation. Development of the muscular layers occurred in a sequential manner; the inner circular layer on the 7th day, the outer longitudinal layer on the 8th day and the muscularis mucosae on the 9th day. Glandular development began on the 13th day of incubation. The epithelium was pseudostratified columnar that consisted of mucous cells, dendritic cells, and keratinocyte precursors. Epithelial stratification occurred on the 15th day of incubation. We used Mallory trichrome, Weigert-Van Gieson, and Gomori silver stains to visualize fibrous components. Scanned samples showed formation of endoderm and mesoderm on the 5th day of incubation. A layer of myoblasts developed on the 8th day of incubation. Formation of mucosal folds, which contained glandular openings, occurred on the 14th to 17th days of incubation. On the 5th to 8th days of incubation, CD34 and vascular endothelial growth factor (VEGF) positive-mesodermal cells, and telocytes (TCs) were detected. On the 15th day of incubation, CD34 and VEGF positive-telocytes, and fibroblasts, were identified. The current study described the correlations between functional morphology and evolutionary biology.

Influence of warming temperatures on coregonine embryogenesis within and among species

Abstract: The greatest known global response of lakes to climate change has been an increase in water temperatures. The responses of many lake fishes to warming water temperatures are projected to be inadequate to counter the speed and magnitude of climate change. We experimentally evaluated the responses of embryos from a group of cold, stenothermic fishes (Salmonidae Coregoninae) to increased incubation temperatures. Study groups included cisco (Coregonus artedi) from lakes Superior and Ontario (USA), and vendace (C. albula) and European whitefish (C. lavaretus) from Lake Southern Konnevesi (Finland). Embryos from artificial crossings were incubated at water temperatures of 2.0, 4.5, 7.0, and 9.0°C, and their responses were quantified for developmental and morphological traits. Embryo survival, incubation period, and length-at-hatch were inversely related to incubation temperature whereas yolk-sac volume increased with incubation temperature within study groups. However, varying magnitudes of responses among study groups suggested differential levels of developmental plasticity to climate change. Differential levels of parental effects indicate genetic diversity may enable all study groups to adapt to cope with some degree of changing environmental conditions. Our results suggest that the coregonines sampled within and among systems may have a wide range of embryo responses to warming incubation conditions.

Distribution of incubation periods of COVID-19 in the Canadian context.

Abstract: We propose a novel model based on a set of coupled delay differential equations with fourteen delays in order to accurately estimate the incubation period of COVID-19, employing publicly available data of confirmed corona cases. In this goal, we separate the total cases into fourteen groups for the corresponding fourteen incubation periods. The estimated mean incubation period we obtain is 6.74 days (95% Confidence Interval(CI): 6.35 to 7.13), and the 90th percentile is 11.64 days (95% CI: 11.22 to 12.17), corresponding to a good agreement with statistical supported studies. This model provides an almost zero-cost computational complexity to estimate the incubation period.

Variation in incubation length and hatching asynchrony in Eastern Kingbirds: Weather eclipses female effects

Abstract: Incubation length and hatching asynchrony are integral elements of the evolved reproductive strategies of birds. We examined intra- and interpopulation variation in both traits for Eastern Kingbird (Tyrannus tyrannus) populations from New York (NY), Kansas (KS), and Oregon (OR) and found that both incubation length and hatching asynchrony were not repeatable among females, after controlling for a repeatable trait, clutch size. Instead, incubation length and clutch size were influenced by ambient temperature and precipitation. Incubation length exhibited the same median (15 days) and range (13–17 days) at all sites. Model selection results indicated that incubation periods for the smallest and largest clutches were longer in NY than KS when rain was frequent throughout incubation, in replacement nests, and likely when ambient temperatures were low during egg-laying. Full hatching usually required 2 days (but up to 3), with synchronous hatching associated with small clutch sizes, short incubation periods, frequent rain during the egg-laying period, and low ambient temperatures during the first half of incubation. Nestling starvation was uncommon (5–9% of nestlings monitored) and not associated with greater hatching asynchrony. These results indicate that while clutch size, a repeatable female trait, contributed to variation in incubation length and hatching asynchrony in Eastern Kingbirds, weather was a greater source of variation, especially for incubation length.LAY SUMMARYThe length of time that eggs remain in a nest exposed to causes of mortality has important influences on the reproductive success of birds.We collected data on incubation length, the length of time elapsed between the hatching of the first and last egg (called hatching asynchrony), and probability of nestling starvation in Eastern Kingbirds breeding at 3 locations (Kansas, New York, and Oregon).Incubation length and hatching asynchrony varied considerably within, but also among sites. Incubation length and hatching asynchrony were both greater in nests with more eggs. However, most other variation was likely due to environmental effects. Cool and wet conditions were associated with long incubation periods while greater hatching asynchrony was found during periods when it was warm and dry.Starvation of nestlings was infrequent, and nests with a greater range of nestling ages (caused by high hatching asynchrony) did not experience greater starvation of young. Nestling starvation was thus not a cost of high-hatching asynchrony.Our research demonstrates that environmental temperature and frequency of precipitation have greater effects on incubation period compared to clutch size.

Impact of delays to incubation and storage temperature on blood culture results: a multi-centre study

Abstract: Blood cultures are one of the most important tests performed by microbiology laboratories. Many hospitals, particularly in low and middle-income countries, lack either microbiology services or staff to provide 24 h services resulting in delays to blood culture incubation. There is insufficient guidance on how to transport/store blood cultures if delays before incubation are unavoidable, particularly if ambient temperatures are high. This study set out to address this knowledge gap. In three South East Asian countries, four different blood culture systems (two manual and two automated) were used to test blood cultures spiked with five common bacterial pathogens. Prior to incubation the spiked blood culture bottles were stored at different temperatures (25 °C, in a cool-box at ambient temperature, or at 40 °C) for different lengths of time (0 h, 6 h, 12 h or 24 h). The impacts of these different storage conditions on positive blood culture yield and on time to positivity were examined. There was no significant loss in yield when blood cultures were stored < 24 h at 25 °C, however, storage for 24 h at 40 °C decreased yields and longer storage times increased times to detection. Blood cultures should be incubated with minimal delay to maximize pathogen recovery and timely result reporting, however, this study provides some reassurance that unavoidable delays can be managed to minimize negative impacts. If delays to incubation ≥ 12 h are unavoidable, transportation at a temperature not exceeding 25 °C, and blind sub-cultures prior to incubation should be considered.

Analysis of Environmental Variables and Carbon Input on Soil Microbiome, Metabolome and Disease Control Efficacy in Strawberry Attributable to Anaerobic Soil Disinfestation

Abstract: Charcoal rot and Fusarium wilt, caused by Macrophomina phaseolina and Fusarium oxysporum f. sp. fragariae, respectively, are major soil-borne diseases of strawberry that have caused significant crop losses in California. Anaerobic soil disinfestation has been studied as an industry-level option to replace soil fumigants to manage these serious diseases. Studies were conducted to discern whether Gramineae carbon input type, incubation temperature, or incubation duration influences the efficacy of this disease control tactic. In experiments conducted using 'low rate' amendment applications at moderate day/night temperatures (24/18 °C), and carbon inputs (orchard grass, wheat, and rice bran) induced an initial proliferation and subsequent decline in soil density of the Fusarium wilt pathogen. This trend coincided with the onset of anaerobic conditions and a corresponding generation of various anti-fungal compounds, including volatile organic acids, hydrocarbons, and sulfur compounds. Generation of these metabolites was associated with increases in populations of Clostridium spp. Overall, carbon input and incubation temperature, but not incubation duration, significantly influenced disease suppression. All Gramineae carbon inputs altered the soil microbiome and metabolome in a similar fashion, though the timing and maximum yield of specific metabolites varied with input type. Fusarium wilt and charcoal rot suppression were superior when anaerobic soil disinfestation was conducted using standard amendment rates of 20 t ha-1 at elevated temperatures combined with a 3-week incubation period. Findings indicate that anaerobic soil disinfestation can be further optimized by modulating carbon source and incubation temperature, allowing the maximum generation of antifungal toxic volatile compounds. Outcomes also indicate that carbon input and environmental variables may influence treatment efficacy in a target pathogen-dependent manner which will require pathogen-specific optimization of treatment protocols.

Wider Angle Egg Turning during Incubation Enhances Yolk Utilization and Promotes Goose Embryo Development.

Abstract: We aimed to investigate how wide-angle turning of eggs during incubation affected yolk utilization and the associated molecular mechanism, along with improved goose embryonic development. In total, 1152 eggs (mean weight: 143.33 ± 5.43 g) were divided equally and incubated in two commercial incubators with tray turning angles adjusted differently, to either 50° or 70°. Following incubation under the standard temperature and humidity level, turning eggs by 70° increased embryonic days 22 (E22), embryo mass, gosling weight at hatching, and egg hatchability, but reduced E22 yolk mass compared with those after turning eggs by 50°. Lipidomic analyses of the yolk revealed that egg turning at 70° reduced the concentrations of 17 of 1132 detected total lipids, including diglycerides, triglycerides, and phospholipids. Furthermore, the 70° egg turning upregulated the expression of genes related to lipolysis and fat digestion enzymes, such as lipase, cathepsin B, and prosaposin, as well as apolipoprotein B, apolipoprotein A4, very low-density lipoprotein receptor, low-density lipoprotein receptor-related protein 2, and thrombospondin receptor, which are genes involved in lipid transportation. Thus, a 70° egg turning angle during incubation enhances yolk utilization through the upregulation of lipolysis and fat digestion-related gene expression, thereby promoting embryonic development and improving egg hatchability and gosling quality.

Near-infrared calibration models for estimating volatile fatty acids and methane production from in vitro rumen fermentation of different total mixed rations

Abstract: Volatile fatty acids (VFA) and methane (CH4) are the major products of rumen fermentation. The VFA are considered an energy source for the animal and rumen microbiota, and CH4 (which is released by eructation) is considered an energy loss. Quantification of these fermentation products is fundamental for the evaluation of feeds and diets, and provides important information regarding the use of nutrients by ruminants. Near-infrared (NIR) spectroscopy is increasingly used for the evaluation of animal feeds because it is rapid, nondestructive, noninvasive, and inexpensive; does not require reagents; and the results are reproducible. The aim of this study was to develop NIR calibration models for estimating the production of VFA (acetic, propionic, butyric, valeric, isovaleric, and isobutyric acids), total gas, and CH4 using in vitro gas production tests with buffered rumen inoculum throughout fermentation. Fifty-four total mixed rations (TMRs) were examined, and rumen fluid was manually collected from 2 dry Holstein dairy cows that had ruminal fistulas and were fed at maintenance energy levels. Then, 30 mL of buffered rumen fluid was incubated in bottles with ∼220 mg of TMR. The total gas, VFA, and CH4 were measured after 2, 5, 9, 24, 30, 48, and 72 h of rumen incubation for each TMR. The VFA were measured on 32 randomly selected TMR. In particular, 7 bottles were used for each TMR, one for each incubation time. Methane was measured in the headspace and VFA were measured in the buffered rumen fluid. The bottles were considered experimental units for calibration purposes. The production of CH4 was quantified from the bottle headspaces by gas chromatography, and total gas production was measured using a pressure transducer at each incubation time. Two aliquots of the fermented liquids were sampled by opening the bottles at each incubation time, and (1) the concentrations of VFA were determined by gas chromatography or (2) spectra were obtained from Fourier-transform NIR spectroscopy. The data were randomly divided into calibration and validation data sets. The average concentrations of acetic acid (45.30 ± 11.92 and 43.86 ± 11.93 mmol/L), propionic acid (14.97 ± 6.08 and 14.38 ± 6.56 mmol/L), butyric acid (8.47 ± 3.47 and 8.65 ± 3.79 mmol/L), total gas (111.34 ± 81.90 and 116.46 ± 82.44 mL/g of organic matter), and CH4 (9.65 ± 9.45 and 10.35 ± 9.33 mmol/L) were similar in the 2 data sets. The best calibration models were retained based on the coefficient of determination (R2) and the ratio of prediction to deviation (RPD). The R2 values for prediction of VFA ranged from 0.69 (RPD = 3.28) for valeric acid to 0.94 (RPD = 4.20) for acetic acid. The models also provided good predictions of CH4 (R2 = 0.89, RPD = 3.05) and cumulative gas production (R2 = 0.91, RPD = 3.30). The models described here precisely and accurately estimated the production of CH4 and VFA during in vitro rumen fermentation tests. Validations at additional laboratories may provide more robust calibrations.

Interaction between eggshell temperature and carbon dioxide concentration after day 8 of incubation on broiler chicken embryo development.

Abstract: Carbon dioxide (CO2) is considered to be an important factor during incubation of eggs Effects attributed to higher CO2 concentrations during experiment might be due to confounding effects of other environmental conditions, such as incubation temperature To disentangle effects of eggshell temperature (EST) and CO2 concentration, an experiment was conducted A total of 630 Cobb 500 hatching eggs from 37 to 45 wk commercial breeder flocks were collected and incubated according to treatments The experiment was setup as a complete randomized 2 × 3 factorial design, resulting in 6 treatments From day 8 of incubation onward, broiler eggs were exposed to one of two EST (378 or 389 °C) and one of three CO2 concentrations (01, 04 or 08%) Eggs were incubated in climate-respiration chambers and metabolic heat production was determined continuously At day 18 of incubation and at 6 h after hatching, embryo and chicken quality were determined by evaluation of organ weights, navel condition, blood metabolites and hepatic glycogen Hatching time and chicken length at 6 h after hatching showed an interaction between EST and CO2 concentration (both P = 0001) Furthermore, no effect of CO2 concentration was found on embryo development or chicken quality Metabolic heat production between day 8 and 18 of incubation was not affected by either EST or CO2 At day 18 of incubation, an EST of 389 °C resulted in a higher egg weight loss, longer embryos, higher yolk free body mass (YFBM) and lower heart weight than an EST of 378 °C (all P < 0008) At 6 h after hatching, an EST of 389 °C resulted in a higher residual yolk weight and lower YFBM, liver weight and heart weight than an EST of 378 °C (all P < 0003) Lactate, uric acid and hepatic glycogen were not affected by EST at either day 18 of incubation or at hatch Glucose was not affected by EST at day 18 of incubation, but at hatch, it was higher at an EST of 378 °C than at an EST of 389 °C (P = 002) It can be concluded that effects of CO2 concentration (at concentrations ≤08%) on embryonic development and chicken quality appear to be limited when EST is maintained at a constant level Moreover, a higher EST from day 8 of incubation onward appears to negatively affect chicken quality at hatch

Comprehensive estimation for the length and dispersion of COVID-19 incubation period: a systematic review and meta-analysis.

Abstract: To estimate the central tendency and dispersion for incubation period of COVID-19 and, in turn, assess the effect of a certain length of quarantine for close contacts in active monitoring. Literature related to SARS-CoV-2 and COVID-19 was searched through April 26, 2020. Quality was assessed according to Agency for Healthcare Research and Quality guidelines. Log-normal distribution for the incubation period was assumed to estimate the parameters for each study. Incubation period median and dispersion were estimated, and distribution was simulated. Fifty-six studies encompassing 4095 cases were included in this meta-analysis. The estimated median incubation period for general transmissions was 5.8 days [95% confidence interval (95% CI): 5.3, 6.2]. Incubation period was significantly longer for asymptomatic transmissions (median: 7.7 days; 95% CI 6.3, 9.4) than for general transmissions (P = 0.0408). Median and dispersion were higher for SARS-CoV-2 incubation compared to other viral respiratory infections. Furthermore, about 12 in 10,000 contacts in active monitoring would develop symptoms after 14 days, or below 1 in 10,000 for asymptomatic transmissions. Meta-regression suggested that each 10-year increase in age resulted in an average 16% increment in length of median incubation (incubation period ratio, 1.16, 95% CI 1.01, 1.32; P = 0.0250). This study estimated the median and dispersion of the SARS-CoV-2 incubation period more precisely. A 14-day quarantine period is sufficient to trace and identify symptomatic infections.