Lethality Values Research Articles

Initial antimicrobial therapy and case fatality in patients with community-acquired pneumonia

The health importance of community-acquired pneumonia is an unquestionable fact given its relationship with hospital and overall mortality. The objective of the investigation was to evaluate the relationship between selected antimicrobials used in the initial treatment (amoxicillin/sulbactam, cefuroxime, ceftriaxone and cefotaxime) and mortality from pneumonia. An observational study was carried out, with a descriptive design and a population of 1,809 patients with pneumonia hospitalized between 2012 and 2019; the necessary information was obtained from the clinical history. Statistical processing was performed using bivariate and multivariate analysis (logistic regression); the ratio of cross products (odds ratio) and its 95% confidence interval were used as a statistician. Among the results, the following stand out: significantly higher lethality values were found in those treated with cefotaxime (33%) than in those who received amoxicillin/sulbactam (24%, OR 1.6[1.0001;2.6]), as well as in those treated with ceftriaxone (30%) compared with those treated with amoxicillin/sulbactam (24%, OR 1.3[1.05;1.8]) and with cefuroxime (24%, OR 1.3[1.04;1.7]). A higher frequency of patients with extensive pneumonia, of patients in a critical state on admission, and of bedridden occurrence during hospitalization were identified in those treated with cefotaxime. In patients with “moderate pneumonia and high probability of unfavorable outcome”, treatment with ceftriaxone or cefotaxime was associated with death; as well as ceftriaxone treatment for all subjects. It is concluded that the initial treatment with amoxicillin/ sulbactam or cefuroxime was more favorable than the use of third generation cephalosporins. Also in the global analysis, the absence of differences in lethality between those treated with amoxicillin/sulbactam and with cefuroxime was recognized.

Lethality of Birth Defects in Live Born Infants Categorized by Gestational Age and Birth Weight.

This study aimed to describe lethality of birth defects (BDs) in newborns categorized by gestational age and birth weight and to identify BDs associated with prematurity. Live born infants (n = 16,452) with isolated BDs classified by severity, and 42,511 healthy controls were assigned to categories: adequate growth, preterm, or small for gestational age (SGA). Proportion of cases and BDs' lethality rates were obtained by category and compared with controls. Overall fewer malformed than nonmalformed infants were of adequate growth, while the opposite occurred in the preterm and SGA categories where gastroschisis and esophageal atresia were among the most outstanding defects. For most severe BDs, the early neonatal death rate was higher than control values in all categories; for mild defects, except cleft lip in the preterm category, they did not differ. Diaphragmatic hernia showed the highest lethality values, while those of spina bifida were among the lowest. Talipes, hypospadias, and septal heart defects were mild defects significantly associated with prematurity. Although reasons, such as induced preterm delivery of fetuses with certain anomalies, could partially account for their high prematurity rates, susceptibility to preterm birth might exist through underlying mechanisms related with the defects. The identification of BDs associated with prematurity should serve to improve measures that prevent preterm birth especially of fetuses at risk. · Some BDs predispose to prematurity.. · Prematurity is an additional risk factor for mortality in infants with mild defects.. · Lethality values should be adjusted by gestational age and birth weight..

Thermosonication technology and its application in food industry

Nowadays, consumers prefer nutritious and safe food products having natural taste and freshness. It is known that traditional thermal techniques can extend the shelf life of food products and their safety, but they cause loss in nutritional parameters. Thermosonication (TS) is an emerging non thermal processing technique used for food. It is a combined method of thermosonication and heat. The product is subjected to ultra- sound and moderate heat simultaneously and they both together have some synergistic effect. Thermosonication is a form of energy generated by sound waves of frequencies that are greater than the upper limit of human hearing range, typically above 20 kHz. By coupling thermosonication with thermal treatment, increased levels of microbial kill can be achieved while minimizing changes to the organoleptic properties of foods. The advantages of sonoprocessing over thermal treatment are minimal flavour loss, significant energy saving and greater homogeneit. The process of thermosonication has been used for microbial and enzyme inactivation. This method produces a greater effect on inactivation of microorganisms than heat alone. When thermosonication is used for pasteurization or sterilization purpose, lower process temperatures and processing times are required to achieve the same lethality values as with conventional processes. It is also more efficient, safe and reliable than thermosonication application alone by itself to achieve the limit of food-borne pathogens destruction. Thermosonication is a valuable method to reduce the microbial load, saving cost and energy and being less aggressive against food properties than heat treatments alone. The enzymes and microbial inactivation by thermosonication treatment is attributed to heat and cavitation, which is the phenomenon of formation, growth and explosion of bubbles in a liquid. During implosion, very high temperatures (approximately 5000 K) and pressures (estimated at 50000 kPa) are reached inside these bubbles. The explosion leads disruption of cell wall of micro-organisms causing their death. The process of thermosonication is used for extending the shelf life of liquid food like fruit juices.

Heating of liquid foods in cans: Effects of can geometry, orientation, and food rheology

AbstractIn this work, the effect of geometry and orientation of food cans on the heating characteristics of processed liquid foods and the resulting lethality target values as a function of the processing times have been investigated. For this purpose, the governing differential equations have been solved numerically for elliptical and cylindrical cans of varying aspect ratios in different orientations in order to delineate their effect on the heating rate (especially of the slowest heating zone [SHZ]) and lethality values over wide ranges of rheological features including shear thinning (n < 1), Newtonian (n = 1), and shear thickening (n > 1) behaviors. The flow and heat transfer characteristics were analyzed with the help of velocity vectors, isotherm contours, average Nusselt number, SHZ temperature and heat penetration parameters, and lethality target values. Also, comparisons were made in terms of the sterilization time and heat penetration parameters to identify the preferable geometries and orientations of food cans for effective heating of non‐Newtonian foodstuffs. Finally, favorable conditions in terms of the shape and orientation of the can and the rheological properties have been delineated which lead to superior heating characteristics.Practical ApplicationsProcessed foodstuffs are produced in various forms ranging from that in solid, liquid, or as heterogeneous mixtures. Often such liquid and heterogeneous suspensions products are viscous non‐Newtonian in character and their thermal processing (including pasteurization, sterilization, etc.) tends to be much more challenging than that of their Newtonian counterparts like air and water. This work explores heating of non‐Newtonian liquid foodstuffs in cans of various shapes, geometries and in different orientations in the free convection regime. The results show that depending upon the rheological properties of the products, some orientations and/or geometries offer potential advantages in terms of shorter processing times and lethality values. This information can be of great potential in customizing the design of containers for different food products as well as of different rheological properties.

Quantitative risk assessment of fire & explosion for regasification process of an LNG-FSRU

As global energy consumption is continuously on the rise, there is an increasing interest in the design of floating liquefied natural gas (LNG) regasification facilities in order to prepare for additional energy demand. In this study, following a process simulation to find operational conditions, a quantitative risk assessment (QRA) was performed for a regasification process of an LNG floating storage and regasification unit (FSRU). The regasification process was designed and simulated considering the required gas processing capability to obtain the thermodynamic states and operation conditions. A QRA was performed with combinations of frequencies and consequences of fire and explosion. The leak frequencies, representative hole sizes, and ignition probabilities for four hole size categories were estimated. Consequence simulation was conducted to assess risk results. The probabilistic safety distance for the flame length was estimated. The final risk consequences were obtained as number of fatalities per year by applying lethality values. The individual risk was found to be in as low as reasonably practicable (ALARP) ron compared to acceptance criteria. An f-N curve for fatality showed that the group risk is also in ALARP ron. The method and results presented in this study will help design LNG-FSRUs and other LNG facilities.

Simulation of Microwave Assisted Finish Drying and Inactivation of Escherichia Coli, Bacillus Cereus and Staphylococcus Aureus of Onion Powder

The onion powder with initial moisture content of 10% (db) in form of thin infinite layer of thickness 5mm was dried using a laboratory microwave oven at 50W/g microwave power density to final moisture content of 2% (db).The temperature, moisture change pattern of the experimental process was monitored. Computer simulation of the predicted temperature pattern with drying time was obtained by using the mathematical model governed by energy balance equation and using data of the thermo-physical properties of the onion powder obtained either experimentally or through literature review. The usage of high microwave power to mass ratio results in raised temperature with reduced drying time. The decrease in drying rate is due to initial moisture content. Effective moisture diffusivity increases with decreasing moisture content due to the application of high power density. Lethality values for Escherichia coli, Bacillus cereus spores and Staphylococcus aureus, which are more prominent in onion powder, were then evaluated from the simulated temperature curve. DT and z values were used to estimate the sterilization values for each individual microorganism. It was observed that significant sterilization of E.coli and S.aureus start after 35 s at a minimum temperature of 89oC with 0.047 and 0.044 log reduction while, for B.cereus it starts after 75 s at 117oC with 0.431 log reduction. The maximum temperature of 117ᵒC was limited due to unacceptable sensory quality of end product.

Lethality Calculation of Particulate Liquid Foods during Aseptic Processing

In the past two decades, aseptic processing has been implemented in the food industry to sterilize particulate liquid food mixtures. To ensure that particulates in the liquid receive sufficient heating, mathematical modeling is employed to evaluate the temperature and lethality level in the particles. We developed a model for the thermal processing of liquid foods containing cubic particles in a continuous laminar pipe flow system, comprising a tubular heat exchanger. In our simplified approach, heat transfer equations for particulate liquid foods were solved analytically and numerically to evaluate the effect of certain process parameters on the time temperature profiles of particles and the lethality value in the products. A comparison of the particles’ lethality values was made between the experiment and simulation for two different particle residence times in a case study, and the model predictions were in good agreement with experimental data. Based on modeling studies, it was found that within the range of parameters studied, an increase in flow rate and particle size resulted in a decrease in the lethality value of the particles, while an increase in particle concentration and holding tube length resulted in the opposite effect.

High pressure processing effect on different Listeria spp. in a commercial starter-free fresh cheese

In this study, both microbial inactivation and growth of Listeria spp. inoculated in commercial free-starter fresh cheese was evaluated after high-pressure processing (HPP). HPP conditions (300, 400, 500 and 600 MPa at 6 °C for 5 min) and inoculum level (3–4 or 6–7 log CFU/g of cheese), as well as differences among strains inoculated (Listeria innocua, L. monocytogenes CECT 4031 and L. monocytogenes Scott A) were investigated. Inactivation and generation of sublethal injury were determined after HPP using ALOA (Agar Listeria according to Ottaviani and Agosti) and TAL (Thin Agar Layer) plating methods, respectively. Listeria inactivation increased with the pressure applied, presenting some statistical differences between the employed strains, inoculum level and sublethal injury. The highest lethality values were obtained at 600 MPa for the three strains tested, although the 500 MPa treatment presented high lethality for L. innocua and L. monocytogenes CECT 4031. After treatment, L. innocua and L. monocytogenes CECT 4031 counts in fresh cheese increased gradually during cold storage. By contrast, counts in cheeses inoculated with L. monocytogenes Scott A did not change significantly (p ≥ 0.05), being this strain the most pressure resistant and with the slowest growth rate. The manuscript present information supporting that, strains with high-level resistance should be employed during inactivation studies, instead of surrogate microorganisms. Application of HPP treatments of 500 MPa and especially 600 MPa on fresh cheeses would be effective to eliminate the most resistant microorganism to a level that should not present a public health risk under normal conditions of distribution and storage.

Variability in foraging behaviour, thermal requirement and virulence of entomopathogenic nematodes against sod webworm, Herpetogramma phaeopteralis Guene� (Lepidoptera: Crambidae)

Variability in virulence among entomopathogenic nematodes, Heterorhabditis indica , H. bacteriophora and Steinernema abbasi , was studied for lethality, foraging behaviour in response to host volatiles, thermal requirements (degree-days), recyclability, persistence and field efficacy against Turfgrass Sod Webworm (TSW), Herpetogramma phaeopteralis . Comparatively, lethal concentration and time were lowest for H. indica against TSW. Recyclability of EPN ranged from 3.42 × 10 5 to 4.23 × 10 5 IJs g 1 of TSW. H. bacteriophora recorded highest movement rate on agar (0.38–0.78cm) and sand-agar (0.45–0.56cm), followed by S. abbasi , and H. indica . Responding to TSW volatiles, S. abbasi recorded maximum movement, H. bacteriophora , moderate, and H. indica , lowest. Heterorhabditis indica (with nictitation); S. abbasi and H. bacteriophora (without nictitation) were ambusher and cruiser, respectively. S. abbasi preferred warmer temperatures (30–33°C), H. bacteriophora , moderate (24–27°C), and H. indica , a wider range (24–30°C), for virulence based on thermal requirement. In field, EPNs were comparable to chlorpyriphos against TSW. We demonstrated the complementarity of thermal preferences of EPNs and insect pest was critical besides attributes like foraging behaviour, recyclability, persistence, and lethality values for their success in the field.

238 The effect of container size and type on lethality values during production of thermally processed wet pet foods

238 The effect of container size and type on lethality values during production of thermally processed wet pet foods

Effects of Packaging Geometry on Heat Penetration Time in Retortable Semi-Rigid Plastic Trays

Semi-rigid, retortable trays were filled with a food simulate and thermally processed in a water immersion automated batch retort system at rotational speeds of 6 RPM and 11 RPM. Triangle, rectangle, oval, and round trays were evaluated, each having approximately the same overflow capacity. During processing, trays were fixed in place with racks containing one shape per rack. Various rack location combinations were tested to provide processing data for each shape in each rack location. Heat penetration data was gathered using thermocouples located in the geometric center of each tray shape and this data was modeled to determine the slowest heating container. No differences were observed in rack location among tray geometries at either RPM level (P>0.05). The data generated during heat penetration runs was also used to model different retort temperatures and lethality values. A retort temperature of 215°F and a lethality value of 10 showed the highest average sterilization time (P 0.05) than any other shape tray. At a rotational speed of 11 RPM, differences in average process time to reach lethality between tray geometries were insignificant (P>0.05).

Comparison of spore inactivation with novel agitating retort, static retort and combined high pressure-temperature treatments

Optimization of food preservation technologies is necessary for improved product quality and nutrition as well as energy and environmental sustainability. In the current study, inactivation of Bacillus subtilis spores in a model soup (pH 6.1) with agitating retort, static retort and combined high pressure-temperature treatments was investigated. With isothermal experiments, D95° C and z values for B. subtilis spores in the soup were obtained as 4.67 min and 8.65 °C. Log-linear model performed well for describing isothermal spore inactivation kinetics with satisfactory R2adj values (0.94–0.97). Agitating retort treatments caused a dramatic reduction in processing times, as 17 min processing in agitating mode was required for 7-log inactivation of B. subtilis spores, compared to 53 min in static mode at 110 °C. For agitating process, observed and predicted lethality values were similar. This implied a homogenous heat load distribution within the soup with the help of high frequency agitation. Combined HPP and mild temperature treatments were highly synergistic for elimination of B. subtilis spores in the same model soup used in heat treatments. HPP treatments combining 650 MPa and 55–65 °C for 10 min resulted in up to 4.5 log kill effect on spores. The findings from the current study can be utilized in selection of test conditions for similar products in future safety studies. Results clearly showed that using novel mechanisms in food processing provide an opportunity for milder processing which can lead to better food quality and sustainability.

Improving the efficiency of ultra-high pressure homogenization treatments to inactivate spores of Alicyclobacillus spp. in orange juice controlling the inlet temperature

Samples of orange juice inoculated with strain CECT 7094 of Alicyclobacillus acidoterrestris or strain CECT 5324 of Alicyclobacillus hesperidum were pre-heated to five different temperatures (20, 50, 60, 70 and 80 °C) before applying a 300 MPa Ultra High Pressure Homogenization (UHPH) treatment. Treated and control samples were kept during 30 days at 22 °C, 30 °C and 43 °C to evaluate the ability of the surviving spores to germinate and grow. UHPH treatments hardly affected the spore counts at the lowest inlet temperature (20 °C), but significant reductions were observed when inlet temperature raised to 60 °C, achieving lethality values above 5 Log CFU/ml when juice samples were pre-heated at 70 for A. hesperidum and 80 °C for A. acidoterrestris. During the later storage of the juice samples Alicyclobacillus counts increased significantly during the first 15 days in samples pre-heated at 20 °C and 50 °C when they were stored at both 30 °C and 43 °C, achieving similar counts than control samples, but not at 22 °C. Nevertheless, in samples pre-heated at 70 and 80 °C spore counts remained below the detection limit indicating that these treatments were the most efficient inactivating Alicyclobacillus spp. spores.

The link between cell-cycle dependent radiosensitivity and repair pathways: a model based on the local, sister-chromatid conformation dependent switch between NHEJ and HR.

The different DNA damage repair pathways like homologous recombination (HR) and non-homologous end joining (NHEJ) have been linked to the variation of radiosensitivity throughout the cell cycle. However, no attempts have been made to test the various hypotheses derived from these studies in a quantitative way e.g. by using modeling approaches. Here we present the first modeling approach that allows predicting the cell cycle dependent radiosensitivity of repair proficient as well as of repair deficient cell lines after photon irradiation based on a small set of parameters and assumptions. A key element of the model is the classification of DNA damage according to its complexity on the level of chromatin loops of about 2Mbp size. Isolated DSB (iDSB), characterized by a single DSB within a chromatin loop, are distinguished from clustered DSB (cDSB), characterized by two or more DSB within a chromatin loop. The class of iDSB is further subdivided into two sub-classes, characterized by the replication status of the corresponding chromatin loop. For iDSB in replicated loops that are in close contact, error-free homologous recombination is assumed to be effective; in unreplicated loops or in replicated loops that have already been separated, iDSB are assumed to be repaired by error-prone non-homologous end joining. cDSB are assumed not to be repairable effectively by neither HR nor NHEJ. Assigning empirically derived lethalities to these three damage classes and pathways, we demonstrate that the model is able to accurately reproduce cell cycle dependent survival probabilities. Notably, the relevant parameters are derived solely from two survival curves for normal, repair proficient cells in G1 and late-S phase. Based on a comparison of model predictions with a large data set reported in the literature, we show that the lethality values for wild type cells are simultaneously predictive for the cell cycle dependent variation of sensitivity observed for HR-deficient and NHEJ-deficient cells.

Modeling the effects of process conditions on the accumulated lethality values of thermally processed pickled carrots

Shelf-stable pickled products are thermally processed to ensure safety and stability. Carrots packed in glass jars and processed in a boiling water bath were chosen to construct models to predict accumulated lethality values given process conditions and heating times. Mixed models with a natural logarithmic transformation of accumulated lethality as response showed that the effect of blanching prior to filling did not significantly impact the response (P > 0.05), while the effects of ln process time, jar size, carrots to brine ratio, carrot spear diameter, brine temperature, and concentration of sucrose in the brine and interactions among these variables significantly affected the response (P < 0.001), as evaluated in different experimental designs. The residual unexplained replicate-to-replicate variability of all constructed models was always <3% and every trial was conducted in triplicate. Process authorities can use these models to establish processing guidelines or evaluate current processes for production of shelf-stable pickled carrots or similar foods (as demonstrated by the validation experiments) with pH values from <3.9 to 4.4. This study also demonstrated that it is feasible to use this experimental setup to evaluate the impact of changes in processing conditions on the accumulated lethality values reached through thermal processing of similar foods. Overall, these results contribute to the establishment of science-based processing guidelines that will ensure production of safe and stable products with optimized heating times to enhance quality parameters.

Mosquitocidal efficacy of medicinal plant, Nerium oleander (Apocynaceae), leaf and flower extracts against malaria vector, Anopheles stephensi Liston (Diptera: Culicidae) larvae

ObjectiveTo assess the larvicidal efficacy of five different extracts of Nerium oleander L. (N. oleander) against malaria mosquitoes, Anopheles stephensi (An. stephensi), to combat disease. MethodsThe acetone, benzene, petroleum ether, chloroform, and aqueous extracts from leaves and flowers of N. oleander were subjected to distillation process in a Clevenger type glass apparatus model soxhlet. Larvicidal bioassays were performed to determine their LC50 and LC90 values, regression equation, and 95% confidence with lower and upper limits were calculated using probit analysis. Mortality effect was recorded after 24 h. ResultsThe data indicated that there were significant differences in the lethality (LC50, LC90) values of An. stephensi mosquito larvae among most of the various extracts with their controls. The order of potency with five different concentrations of flower extracts was benzene>chloroform> acetone>petroleum>water. The order of potency with similarly five different concentrations of leaf extracts was chloroform>petroleum>benzene>water>acetone. ConclusionsIt was concluded that there was an overall lethal effect of N. oleander extracts against mosquito, An. stephensi larvae which could be manipulated to develop a safe and effective larvicide.

Comparison of free/bi-axial, fixed axial, end-over-end and static thermal processing effects on process lethality and quality changes in canned potatoes

Thermal processing as the most prevalent food preservation technique has been extensively studied and used for years. Different modes of agitation that can be employed in the canning process are characterized by relatively different, heat impacts and their associated quality changes. Hence, the main objective of this study was to evaluate the impact of different retort conditions on lethality (Fo), color and textural changes in potato cubes. Process variables employed were: retort temperature: 115, 120, 125 ºC; agitation orientations: vertical (end-over-end) and horizontal (fixed and bi-axial); agitation speed: 0 (static), 10, 20 rpm. A water immersion single basket rotary retort was retrofitted to simultaneously accommodate agitating modes of rotation. Accumulated process lethality values were calculated for each experimental run. Color quality in terms of parameters such as, yellowness (b-value), total color difference (ΔE values) and textural quality in terms of hardness values were compared for the particles processed under each condition. All process variables had a significant (p < 0.05) influence on Fo, color and texture parameters of potato particles. The quality changes were found to correlate well with the accumulated Fo values achieved during processing. As can be expected, the quality loss increased with an increase in Fo and vice versa.

Cytotoxic properties of some herbal plants in Oman

Organic extracts from five medicinal plants collected in Oman were assayed for in vitro cytotoxic property. Dried samples from latex, leaves, roots and stem bark of these species were macerated in ethanol to give crude extracts which were Kupchan's partitioned into hexane, chloroform and ethyl acetate fractions. Six different concentrations of each fraction were subjected to brine shrimp test to determine their lethality values. Percent mortalities from each fraction were then converted to LC50 values by Finney probit analysis. Chloroform and ethyl acetate extracts from Calotropis procera latex and aerial part of Rhazya stricta were the most active. LC50 values for C. procera latex were 3.0 and 8.2μg/ml, respectively, while that of R. stricta were 18.1 and 13.9μg/ml, respectively. C. procera and R. stricta growing in Oman are good sources of cytotoxic compounds.

Optimisation of a process for shelf‐stable dietetic Chhana kheer and changes in physicochemical properties during storage

In the production of shelf‐stable dietetic Chhana kheer, optimised levels of Chhana and artificial sweeteners were examined using a stationary retort. The product was characterised by short lag period for heating (jh) (0.78–1.03), small heating rate index (fh) (7.69–17.00 min) and short lag factor for cooling (jc) (0.76–1.06), implying convective heating regime. The total process time B was 19.13–32.98 min for corresponding process lethality values (Fo) of 4.56–25.50 min. Based on optimisation, processing of the dietetic Chhana kheer at 121.40 °C for 20 min was found to be the optimum. Optimised product was stable up to 90 days at 37 °C.

Benchmark Dose Analysis for Bacillus anthracis Inhalation Exposures in the Nonhuman Primate

There is considerable variability in the published lethality values for inhalation exposures of Bacillus anthracis. The lack of consensus on an acceptable dose-response relationship poses a significant challenge in the development of risk-based management approaches for use following a terrorist release of B. anthracis spores. This article reviewed available B. anthracis dose-response modeling and literature for the nonhuman primate, evaluated the use of the U.S. Environmental Protection Agency's Benchmark Dose Software (BMDS) to fit mathematical dose-response models to these data, and reported results of the benchmark dose analysis of suitable data sets. The BMDS was found to be a useful tool to evaluate dose-response relationships in microbial data, including that from B. anthracis exposure. An evaluation of the sources of variability identified in the published lethality data and the corresponding BMDS-derived lethality values found that varying levels of physical characterization of the spore product, differing receptor-specific exposure assumptions, choice of dose metrics, and the selected statistical methods all contributed to differences in lethality estimates. Recognition of these contributors to variability could ultimately facilitate agreement on a B. anthracis dose-response relationship through provision of a common description of necessary study considerations for acceptable dose-response data sets.