Maximum Incubation Time Research Articles

ВЛИЯНИЕ КРАТКОВРЕМЕННОГО ТЕМПЕРАТУРНОГО СТРЕССА НА ПРОРАСТАНИЕ СЕМЯН УКРОПА

New data on the process of germination of dill seeds of the first and second orders after short-term heat stress (40 ° C) have been obtained. Seed germination was carried out in a thermostat. Swollen seeds (four repetitions of 100 seeds) were exposed to a temperature of 40 ° C in accordance with the scheme of the experiment: 0 (control); 1; 2; 3; 4 and 5 days. After incubation, the seeds were transferred to standard (t = 20 ° C) conditions and germinated in Petri dishes on filter paper with-out access to light for 21 days. Methods of analysis of seed germination in dynamics are used. Log-logistic regression with three parameters was used to construct the seed germination curve: b, d, e. All statistical analyses were performed in R version 3.4.3. The duration of the action of high temperature, which has an inhibitory effect on the germination rate and the number of germinated seeds, was revealed. Seeds of the first order in the control and after incubation for 1-3 days germi-nated in a similar way, and with an increase in the incubation period to 4-5 days, the rate of ger-mination decreased sharply. The seeds of the second order were even less resistant to the action of a short high-temperature stressor, and when the seeds were incubated for 3 days and then trans-ferred to standard temperature conditions, germination did not occur. The germination time of 50% of seeds (T50) of the first order as a result of a sequential increase in the incubation period at 40 ° C increased from 0.92 ± 0.11 to 6.4 ± 0.49 (p<0.001) days, respectively. Seeds of the second order during incubation for 1-2 days also germinated significantly slower compared to the control, and in the future germination did not occur. The curves of changes in the index of maximum seed germination, especially for the second order of branching, had a sharp bend when the critical dose of the temperature factor was exceeded. After that, there was a sharp decrease in the speed of seed germination up to a complete stop. The maximum incubation time (at 40 ° C), after which germi-nation is possible under standard temperature conditions, was 3.69 ± 0.06 days for the first order, and 2.00 ± 0.19 days for the second order. The difference was significant at the significance level of p<0.001.

The Impact of Short-term Thermal Stress on the Consequent Germination of Dill Seeds

The authors obtained new data on the germination of dill seeds, which were gathered from the first-order and second-order branches, after short-term thermal stress (40 °C). The seeds were germinated in a thermostat. The swollen seeds (4 replications with 100 seeds each) were incubated at 40 °C for 1 to 5 days. The seeds in the control group were not incubated. After the incubation, the seeds were transferred to the standard (t = 20 °C) conditions and germinated on filter paper in Petri dishes without light for 21 days. In this study, the authors employed the dynamic method of seed germination analysis. To plot the seed germination curve, the authors used a log-logistic regression with three parameters: b, d, and e. The statistical analysis was conducted in R 3.4.3. The authors determined the duration of heat stress that inhibits the germination speed and germination rate of seeds. Seeds gathered from the first-order branches (“first-order seeds” from now onward) after 1-day to 3-day incubation germinated similarly to the control group. Increasing the incubation period to 4–5 days sharply reduced the germination speed. Seeds gathered from the second-order branches (“second-order seeds” from now onward) were less resistant to high-temperature stress. Three-day incubation completely precluded germination. The germination time of 50% (T50) of the first-order seeds slowed by 0.92±0.11–6.4±0.49 days because of the gradual increase in incubation time. The second-order seeds that incubated for 1–2 days germinated significantly slower than the control group seeds. After this point, further incubation precluded germination. Upon reaching the incubation threshold, the germination rate curves steepened and then continued falling up to the full germination stop. The maximum incubation time (at 40 °C), after which germination was possible in standard temperature conditions, was 3.69±0.06 days for the first-order seeds, and 2.00±0.19 days for the second-order roots. The differences in data were statistically significant at p-value < 0.001

11. Evaluation of the Bact/alert® VIRTUO™ in Terms of Time to Detection, Performance, Workflow Efficiency and Impact on Patient Management, Compared to the BACTEC™ FX Automated Blood Culture System

BackgroundBloodstream infections are associated with high rates of morbidity and mortality, therefore prompt identification and antimicrobial susceptibility testing of the causative organism(s) are critical. We compared the microbiological/clinical performance of BacT/ALERT®-VIRTUO™-(BioMerieux) to that of the BACTEC™FX-(BD) instrument, with time-to-detection (TTD, from loading into system until positivity) as the primary outcome. Secondary microbiological outcomes were positivity and contamination rates, hands-on-time, turn-around-time (TAT) and time-to-identification.MethodsWe performed a prospective cross-over study using blood cultures from patients (>18 years) suspected of bacteremia/fungemia, localized in different wards into two strata (Stratum-1: Emergency Department-ED-; Stratum-2: in-hospital patients). Testing was performed in BACTEC™-PlusAerobic/F and BACTEC-Lytic/10-Anaerobic/F bottles and incubated in BACTEC™FX, or BacT/ALERT®FA-Plus and FN-Plus bottles and incubated in VIRTUO™. Initially, each strata was randomly assigned to one of the incubators and then alternated every 2-weeks for 6 months (October-16th-2018 to April-16th-2019). All samples were processed in parallel with the same work-flow from the moment they were flagged positive. Maximum incubation time was 5 days.ResultsWe included a total of 4782 extractions (9510 bottles) in VIRTUO and 5139 (10193 bottles) in BACTEC. The median age was 67 years for both groups and the samples were equally distributed for each ward (ED: VIRTUO 80.9%, BD 76.4%). The number of blood cultures with at least one positive extraction was 873(18.3%) for VIRTUO and 802(15.6%) for BACTEC (p=0.0003). TTD and proportion of aerobic/anaerobic bottles is shown in Table.Hands-on-time was reduced by 15 minutes/day when using VIRTUO.TableConclusionWe have compared on a large scale and in a “real world” setting the performance of two automatic blood culture incubators. TTD was significantly lower for the VIRTUO incubated samples, with differences in both systems depending on the type of bottle (aerobic vs. anaerobic). The number of positive results was significantly higher for the VIRTUO incubated samples, which might impact antimicrobial prescription and clinical outcomes. Disclosures Ana V. Halperin, MD, Biomérieux (Grant/Research Support) José Luis Cortés Cuevas, MD, biomerieux (Research Grant or Support)biomerieux (Research Grant or Support) Juan Antonio Del Castillo Polo, MD, Biomérieux (Research Grant or Support) Sergio Talens, n/a, Biomerieux (Research Grant or Support) Robert Birch, n/a, bioMerieux Inc. (Employee) Rafael Cantón, PharmD PhD, Biomérieux (Grant/Research Support)

Photodynamic therapy for cutaneous squamous cell carcinoma in situ: Impact of anatomic location, tumor diameter, and incubation time on effectiveness

Photodynamic therapy (PDT) has been reported as a treatment for cutaneous squamous cell carcinoma in situ (SCCis), but only limited data are available on the effectiveness of PDT with aminolevulinic acid (ALA-PDT). To review the outcomes of SCCis treated with ALA-PDT and examine factors associated with response. A retrospective review identified 58 patients with 68 primary SCCis lesions treated with ALA-PDT and blue light illumination. Patient demographics, lesion features, treatment details, clinical response, and subsequent recurrence were extracted from medical record reviews. On completion of PDT the initial complete response rate was 77.9% and was not associated with the number of PDT treatments. On multivariate analysis factors associated with response were location on the face, tumor diameter <2cm, and longer ALA incubation time. Lesions treated with a maximum incubation time of <3hours had a 53.3% response compared with 84.9% for longer incubation. Subsequent recurrence of SCCis was noted in 7 of 53 cases (13.2%) at a median time of 11.7months. This was a retrospective study performed at a single institution without systematic follow-up. ALA-PDT may be an effective treatment for selected cases of SCCis. Effectiveness is impacted by anatomic location, tumor diameter, and ALA incubation time.

Does microbial nitrogen contamination affect the estimation of crude protein degradability of concentrate feeds?1

The effects of microbial contamination (MC) on CP degradability of concentrate feeds are still controversial. Therefore, the aim of this study was to use 15N to estimate the impact of MC on estimations of CP fractions (the soluble fraction of CP [a], the insoluble but potentially degradable fraction of CP [b], and the rate of digestion of fraction b [kd]) of concentrate feeds. Twelve types of feed were evaluated: 6 energy concentrates—wheat bran (Triticum aestivum L.), rice meal (Oryza sativa L.), ground corn (Zea mays L.), ground sorghum (Sorghum vulgare Pers.), ground corn cob (Zea mays L.), and soybean hulls [Glycine max (L.) Merr.]—and 6 protein concentrates—cottonseed meal (Gossypium hirsutum L.), soybean meal [Glycine max (L.) Merr.], ground bean (Phaseolus vulgaris L.), peanut meal (Arachis hypogaea L.), sunflower meal (Helianthus annuus L.), and corn gluten meal (Zea mays L.). The feeds were divided into 4 groups and were incubated in the rumen of 4 crossbred bulls. The samples were incubated for 0, 2, 4, 8, 16, 24, 48, and 72 h. To estimate the MC of the incubated residues, the ruminal bacteria were labeled with 15N via continuous intraruminal infusion of 15(NH4)2SO4. There was no difference (P = 0.738) between corrected and uncorrected parameters a, b, and kd for all feeds that were evaluated. All of the feed tests followed an exponential model of degradation, and the model fitted well to the data, except for corn gluten meal, probably because the maximum incubation time that was used (72 h) was not long enough to allow for an accurate estimation of the degradation profile. Therefore, correction of ruminal protein degradation to MC is irrelevant with regards to the concentrates that were studied.

In situ and in vitro estimation of mineral release from common feedstuffs fed to cattle

SUMMARYThe objective of the current study was to quantify the dry matter (DM) digestibility, and total ash (TA) and mineral release from 12 concentrate and 12 forage feedstuffs commonly fed to cattle using in situ and in vitro methods. Concentrate and forage feedstuffs were incubated in the rumen of ruminally cannulated beef bulls at eight different time points. Two different trials were conducted for concentrates and forages, with maximum incubation time of 72 and 120 h, respectively. The residue from samples incubated for 24 h were treated with pepsin and hydrochloric acid to simulate abomasum digestion in vitro. The initial and residual samples after in situ and in vitro incubations were measured. An asymptotic model was adopted for estimating solubility of minerals, disappearance rate of DM, and TA. Correlations between feedstuff contents and mineral release were evaluated. Residual samples from rumen fermentation after 24 h were incubated in simulated abomasal conditions and mineral release was measured. Cluster analysis was performed to group feedstuffs in relation to TA release. Large variability was observed between concentrate and forage feedstuffs for all constituents analysed. Large variability was observed for the effective ruminal degradation of TA and individual mineral release. When feedstuffs were clustered according to the immediately soluble fraction (‘a’), the insoluble by potentially releasable fraction (‘b’) and the release rate of ‘b’ (‘kd’,/h) estimates of TA ruminal release, four groups were identified. From group ‘1’ to group ‘4’, an increase in the soluble fraction and a reduction in both moderate releasable fraction and release rate was observed. Neutral detergent fibre content had a negative correlation with mineral release in the rumen, while mineral content had a positive correlation. These results demonstrate that mineral solubilization in the digestive tract is not the limiting factor for mineral absorption from the feedstuffs tested.

Validation of test portion pooling for Salmonella spp. detection in foods

Pathogen monitoring programs play a crucial role in the verification of the effectiveness of implemented hygiene control measures. Sampling and testing procedures included in pathogen monitoring involve the analysis of multiple test portions where all samples must be negative for the presence of pathogens for a certain test portion size. Many food safety programs require increased testing due to the risks that a pathogen may be present. Analyzing more than one test portion could prove to be expensive and labor intensive. When more than one test portion for a specified food item is to be tested, the test portions could be combined to form a pooled test portion to reduce laboratory workload, costs of reagents and further confirmatory steps, but only when evidence is available that pooling does not affect on the number of false negative results for different matrices. This study has been performed to demonstrate the equivalence of test portion pooling for Salmonella detection with five different methods using cultural, ELISA and Real Time PCR technologies. Twenty-three (23) different food items including confectionary products, meal components, infant formula, pet food and powdered beverages were validated. Other complementary parameters like impact of minimum and maximum incubation time for pre-enrichment, temperature profile, pH and Salmonella concentration after the pre-enrichment and background flora have also been considered in the study. The results showed that pooling test portions up to 375g for Salmonella detection is valid for the methods that were tested. Relative level of detection (RLOD50) values for 22 of the food items tested were acceptable (i.e. lower than 2.5) when comparing the reference sample size (25g) against the alternative pooled sample size (375g), provided the enrichment broth was pre-warmed and maximum incubation time is respected.

Does microbial nitrogen contamination affect the estimation of crude protein degradability of concentrate feeds?

The effects of microbial contamination (MC) on CP degradability of concentrate feeds are still controversial. Therefore, the aim of this study was to use N to estimate the impact of MC on estimations of CP fractions (the soluble fraction of CP [a], the insoluble but potentially degradable fraction of CP [b], and the rate of digestion of fraction b [kd]) of concentrate feeds. Twelve types of feed were evaluated: 6 energy concentrates-wheat bran ( L.), rice meal ( L.), ground corn ( L.), ground sorghum ( Pers.), ground corn cob ( L.), and soybean hulls [ (L.) Merr.]-and 6 protein concentrates-cottonseed meal ( L.), soybean meal [ (L.) Merr.], ground bean ( L.), peanut meal ( L.), sunflower meal ( L.), and corn gluten meal ( L.). The feeds were divided into 4 groups and were incubated in the rumen of 4 crossbred bulls. The samples were incubated for 0, 2, 4, 8, 16, 24, 48, and 72 h. To estimate the MC of the incubated residues, the ruminal bacteria were labeled with N via continuous intraruminal infusion of (NH)SO. There was no difference ( = 0.738) between corrected and uncorrected parameters a, b, and kd for all feeds that were evaluated. All of the feed tests followed an exponential model of degradation, and the model fitted well to the data, except for corn gluten meal, probably because the maximum incubation time that was used (72 h) was not long enough to allow for an accurate estimation of the degradation profile. Therefore, correction of ruminal protein degradation to MC is irrelevant with regards to the concentrates that were studied.

The sensitive detection of formaldehyde in aqueous media using zirconium-based metal organic frameworks

The amino derivative of the UiO-66 metal organic framework (MOF) was investigated for potential use as a sensing probe for formaldehyde (FA) in an aqueous medium. The sensitivity and specificity of this MOF probe were virtually unaffected by the presence of other tested reference aldehydes, e.g., propionaldehyde (PA), butyraldehyde (BA), and valeraldehyde (VA). The maximum incubation time for the interaction of the MOF probe against 100ppm of FA standard was estimated at 2min. The linear detection of FA molecules using the proposed probe was performed in the range of 10–100ppm with a limit of detection (LOD) at 4ppm. The stability of the MOF for FA detection was estimated through a series of adsorption-desorption cycles. DFT calculations showed that the selective sensing/capture of FA corresponded to the formation of a stable, non-covalent bond between FA and the C6H3NH2 unit of the MOF. This interaction decreased the HOMO/LUMO gap of FA by approximately 0.8eV, a trend that was not evident for all other aldehydes. The results of FTIR, TGA, and XPS analysis confirmed a small but visible change in the chemical environment of the NH and CH bonds of UiO-66-NH2 upon their interactions with FA molecules. Therefore, the proposed MOF probe appears suitable for sensing FA in an aqueous medium.

Histological Evaluation of the Biocompatibility of Polyurea Crosslinked Silica Aerogel Implants in a Rat Model: A Pilot Study

BackgroundAerogels are a versatile group of nanostructured/nanoporous materials with physical and chemical properties that can be adjusted to suit the application of interest. In terms of biomedical applications, aerogels are particularly suitable for implants such as membranes, tissue growth scaffolds, and nerve regeneration and guidance inserts. The mesoporous nature of aerogels can also be used for diffusion based release of drugs that are loaded during the drying stage of the material. From the variety of aerogels polyurea crosslinked silica aerogels have the most potential for future biomedical applications and are explored here.MethodologyThis study assessed the short and long term biocompatibility of polyurea crosslinked silica aerogel implants in a Sprague-Dawley rat model. Implants were inserted at two different locations a) subcutaneously (SC), at the dorsum and b) intramuscularly (IM), between the gluteus maximus and biceps femoris of the left hind extremity. Nearby muscle and other internal organs were evaluated histologically for inflammation, tissue damage, fibrosis and movement (travel) of implant.Conclusion/SignificanceIn general polyurea crosslinked silica aerogel (PCSA) was well tolerated as a subcutaneous and an intramuscular implant in the Sprague-Dawley rat with a maximum incubation time of twenty months. In some cases a thin fibrous capsule surrounded the aerogel implant and was interpreted as a normal response to foreign material. No noticeable toxicity was found in the tissues surrounding the implants nor in distant organs. Comparison was made with control rats without any implants inserted, and animals with suture material present. No obvious or noticeable changes were sustained by the implants at either location. Careful necropsy and tissue histology showed age-related changes only. An effective sterilization technique for PCSA implants as well as staining and sectioning protocol has been established. These studies further support the notion that silica-based aerogels could be useful as biomaterials.

Development of a Rapid LC-UV Method for the Investigation of Chemical and Metabolic Stability of Resveratrol Oligomers

Resveratrol, piceatannol, ε-viniferin, r-viniferin, r2-viniferin, and hopeaphenol are naturally occurring polyphenols, associated with potentially beneficial health effects. We developed a rapid liquid chromatography-ultraviolet detection (LC-UV) method, allowing for the simultaneous determination of these six compounds in biological samples in less than 2.5 min with standard LC equipment. Using this method for the assessment of the stability of the six analytes, we demonstrated that all stilbene polyphenols disappear rapidly in Dulbecco's modified Eagle's medium (e.g., half-life of resveratrol of 1 h). In contrast, the tetramer hopeaphenol was stable over the maximum incubation time of 72 h. In incubations with liver microsomes, ε-viniferin was rapidly glucuronidated, although to a lower extent than resveratrol. Hopeaphenol was not glucuronidated at all. Given that glucuronidation is the major metabolic pathway for polyphenols, hopeaphenol might exhibit significantly different pharmacokinetic properties than other polyphenols. When chemical and metabolic stability as well as biological activity of hopeaphenol are taken together, these findings warrant further investigation of this polyphenol.

From food‐dependent statistics to metabolic parameters, a practical guide to the use of dynamic energy budget theory

The standard model of the dynamic energy budget theory for metabolic organisation has variables and parameters that can be quantified using indirect methods only. We present new methods (and software) to extract food-independent parameter values of the energy budget from food-dependent quantities that are easy to observe, and so facilitate the practical application of the theory to enhance predictability and extrapolation. A natural sequence of 10 steps is discussed to obtain some compound parameters first, then the primary parameters, then the composition parameters and finally the thermodynamic parameters; this sequence matches a sequence of required data of increasing complexity which is discussed in detail. Many applications do not require knowledge of all parameters, and we discuss methods to extrapolate parameters from one species to another. The conversion of mass, volume and energy measures of biomass is discussed; these conversions are not trivial because biomass can change in chemical composition in particular ways thanks to different forms of homeostasis. We solve problems like "What would be the ultimate reproduction rate and the von Bertalanffy growth rate at a specific food level, given that we have measured these statistics at abundant food?" and "What would be the maximum incubation time, given the parameters of the von Bertalanffy growth curve?". We propose a new non-destructive method for quantifying the chemical potential and entropy of living reserve and structure, that can potentially change our ideas on the thermodynamic properties of life. We illustrate the methods using data on daphnids and molluscs.

SARS incubation and quarantine times: when is an exposed individual known to be disease free?

The setting of a quarantine time for an emerging infectious disease will depend on current knowledge concerning incubation times. Methods for the analysis of information on incubation times are investigated with a particular focus on inference regarding a possible maximum incubation time, after which an exposed individual would be known to be disease free. Data from the Hong Kong SARS epidemic are used for illustration. The incorporation of interval‐censored data is considered and comparison is made with percentile estimation. Results suggest that a wide class of models for incubation times should be considered because the apparent informativeness of a likelihood depends on the choice and generalizability of a model. There will usually remain a probability of releasing from quarantine some infected individuals and the impact of early release will depend on the size of the epidemic. Copyright © 2005 John Wiley & Sons, Ltd.

Electron Microscopic Investigation of the Coating Found on Torus-Bearing Pit Membranes of Botrychium Dissectum, the Common Grape Fern

TEM investigation of the torus-bearing pit membranes in tracheids of Botrychium dissectum wood has revealed in some specimens a coating that covers the pit membrane and torus, and sometimes lines the lumen-side of the tracheary wall. Such coatings have been associated with wound response in dicot woods, but have not previously been reported in the wood of Botrychium. In response to wounding, rhizome sampIes incubated on water-saturated filter paper produced the coating material within 4 days. Rhizome sampIes that were incubated with an ethylene inhibitor for a maximum incubation time of 20 days did not develop the wound-response coating. Therefore, based on experimental evidence the wound response appeared to be ethylene mediated. Field sampIes which were artificially grazed by removing the leaf/spike complex exhibited a displaced wound-response coating in the rhizome. Histochemical studies indicate that the coating material has both pectin and phenolic components.

Creep Deformation of Ta Modified Gamma Prime Single Crystals

AbstractThe role of substitutional element alloying of single phase γ' has become of primary interest to alloy designers who would like to exploit its low density and excellent oxidation resistance. Current γ' alloys have not shown sufficient strength to be useful in a creep limited environment. In order to maximize the potential of single phase γ' alloys and to more fully understand the creep strengthening mechanisms in two phase Ni-base superalloys, it has become necessary to clarify the role of Al-substitution elements. Ta is a potent strengthening element in γ' as well as imparting beneficial surface stability to superalloys; its effect on the creep properties of Ni3Al is the subject of this paper. The 1300°C isotherm of the Ni-Al-Ta system was determined in order to establish the γ' single phase field. Comrpositions were fabricated having chemistries which systematically varied both the Al:Ta ratio at Ni=75% and Ni:(AI+Ta) ratio at Ta=6%. Creep tests were conducted on &lt;001&gt; oriented single crystals at 760, 871 and 982°C. Electron microscopy was used to characterize the nature of slip deformation, confirm phase purity and to determine the existence of tetragonal distortions in these crystals. In this manner the strengthening due to Ta was examined in the absence of grain boundary effects. These γ' mono—crystals did not display classical creep response. Incubation creep was observed in all of the specimens tested. Surprisingly, the maximum incubation time was found to occur in the high ratio Ni:(Al+Ta) compounds, where less than 0.5% creep strain was obtained after 200 hours at stress. After incubation, either tertiary creep leading to failure, or apparently classic primary, secondary and tertiary creep ensued. In addition extremely long elongations, to 85%, were measured.