Production of docosahexaenoic acid by Crypthecodinium cohnii using continuous-mode process

Docosahexaenoic acid (DHA), an omega-3 fatty acid found in cold-water fish, has positive health benefits. While the suggested amount of 220 mg/day for adults may be attained by consuming fish, this may increase exposure to environmental pollutants. The heterotrophic marine alga Crypthecodinium cohnii is an important source of DHA because C. cohnii can accumulate lipid greater than 20% of their biomass with a large fraction of DHA (30-50%). Commercially, DHA production by C. cohnii is conducted in large bioreactors (∼100 m3 capacity) using a batch-mode process. The purpose of this study was to investigate lipid and DHA production by C. cohnii using batch-mode and continuous-mode processes. The long term objective is to maximize DHA production from a safe and reliable marine source.;Batch cultivation of C. cohnii was carried in a 15 L bioreactor vessel at 27°C. C. cohnii (ATCC 30772) was grown in ATCC complex media 460 for 10 days at 25°C, transferred to simple media (9 g/L glucose, 2 g/L yeast, and 25 g/L salt) and incubated statically for 8 days at 25°C. Cultures were subsequently transferred to larger volumes of simple media and incubated at 25°C in an orbital shaker incubator at 100 rpm. At each transfer, a 10% (v/v) inoculum level was maintained. Cultivation of C. cohnii was conducted in a 15 L computer controlled bioreactor vessel. Temperature was maintained at 27°C by a computer controlled heating jacket. A 25% glucose solution was administered continuously at a rate of 0.78 mL/min.;Continuous cultivation of C. cohnii was conducted in two 15 L computer controlled bioreactor vessels. Temperature of both vessels was maintained at 27°C during the growth mode of the study and standard media (25g/L glucose, 5.5g/L yeast, and 25 g/L salt) was administered to both bioreactors. After 40 h, the system was switched to continuous mode where one vessel was maintained as a growth vessel at 27°C, and the other as a lipid accumulation vessel at 17°C. In continuous mode, standard media was administered to the growth vessel and a 25% glucose solution was administered to the lipid accumulation vessel.;In both studies algal growth was monitored spectrophotometrically and measured every 12 h at 470 nm. The biomass concentration, lipid content and fatty acid profile were determined by harvesting samples from the vessel.;Results of the study showed that C. cohnii growth was achieved in batch-mode and continuous-mode cultivation with lipid and DHA production. Maximum values for volumetric DHA productivity, biomass, lipid and DHA concentrations in the batch study were 3.61 mg/L.h, 8.35 g/L, 0.89 g/L and 0.32 g/L respectively. In continuous study the maximum values were 4.132 mg/L.h, 3.75 g/L, 0.55 g/L and 0.145 g/L respectively. Although DHA concentration was higher in the batch mode process, volumetric DHA productivity of continuous mode process exceed volumetric DHA productivity of batch mode because of higher production rate of continuous mode process. These values did not exceed the reported values of other batch processes that used a 50% glucose feed. More research is needed to optimize processing parameters in continuous mode to produce a viable alternative to batch mode processes

University Students’ Understanding of Contract Cheating: A Qualitative Case Study in Kuwait

Contract cheating, or students outsourcing their assignments to be completed by others, has emerged as a significant threat to academic integrity in higher education institutions around the world. During the COVID-19, when traditional face-to-face instruction became unsustainable, the number of contract cheating students increased dramatically. Through focus group interviews, this study sought the perspectives of 25 students enrolled in first year writing in a private higher education institution in Kuwait during the pandemic in 2020–2021, on their attitudes towards contract cheating. MAXQDA 2020 was used to examine the data. The participants believe that the primary motivations for engaging in contract cheating are mainly the opportunities presented by online learning and the psychological and physical challenges they experienced during online learning. Those who did not cheat had some shared traits, such as a competitive spirit, confidence in their talents, and a strong desire to learn. Additionally, those with high moral values avoided cheating. To combat contract cheating, students believe that teaching and evaluation techniques should be drastically altered and that students should be educated about plagiarism, while institutions should impose tougher sanctions on repeat offenders

Comparative morphological differences between umbilical cords from chronic hypertensive and preeclamptic pregnancies.

To compare morphological changes in the umbilical cords from chronic hypertensive and preeclamptic patients having normal or pathological umbilical artery Doppler ultrasonographic results. Umbilical cords from 34 normotensive, 31 chronic hypertensive and 70 preeclamptic women with normal and abnormal Doppler flow velocity waveforms (FVW) at 35-40 gestational weeks were studied. Morphological changes in the umbilical cords were examined on formalin-fixed, paraffin-embedded sections. The total umbilical cord area, total vessel area, and wall thickness of umbilical vessels were measured in systematic random samples using unbiased stereology methods. An ANOVA test was used for statistical analysis. In the chronic hypertensive and preeclamptic groups with normal Doppler FVW, the thickness of the umbilical cord vessels remained nearly constant, whereas both the total area and the lumen area were reduced. These changes correlate with the histopathological findings, suggesting a mainly vasoconstrictive effect. By contrast, analysis of the preeclamptic group with pathologic Doppler FVW showed a comparable reduction of all parameters of the umbilical cord. Histopathological findings were related to smaller, contracted smooth muscle cells of the vessel wall, which is suggestive of a predominant hypoplastic mechanism. As a result of reduced uteroplacental perfusion, fetal hypoxia and intrauterine growth retardation become unavoidable in preeclampsia. The histopathological changes in the umbilical cord between the chronic hypertensive and preeclamptic patients depend on the Doppler results. In conclusion, the umbilical artery Doppler FVW indices provide good values for predicting intrauterine growth retardation in preeclamptic patients.</p

Biological variations of ADAMTS13 and von Willebrand factor in human adults

Background: The ultra-large von Willebrand factor (vWF) multimers are very active and must be degraded by ADAMTS13 for optimal activity. A severe functional deficiency of ADAMTS13 has been associated with thrombotic thrombocytopenic purpura. The correct interpretation of patient vWF and ADAMTS13 plasma levels requires an understanding of the biological variation associated with these analytes. In the present paper, we aimed to determine the biological variation of ADAMTS13 and vWF in human adults. Materials and methods: Blood samples were collected weekly from 19 healthy subjects for 5 consecutive weeks. vWF activity and antigenicity were determined using aggregometric and immunoturbidimetric methods. ADAMTS13 antigenicity and activity were determined by ELISA. Results: The within-subject biological variations for vWF activity and antigenicity were 8.06% and 14.37%, respectively, while the between-subject biological variations were 18.5% and 22.59%, respectively. The index of individuality for vWF activity was 0.44, while vWF antigenicity was 0.64. Similarly, ADAMTS13 activity and antigenicity within-subject biological variations were 12.73% and 9.75%, respectively, while between-subject biological variations were 9.63% and 6.28%, respectively. The ADAMTS13 indexes of individuality were 1.32 and 1.55, respectively. Conclusion: We report high biological variation and individuality in vWF antigenicity and activity levels. However, ADAMTS13 antigenicity and activity displayed high biological variation, but low individuality. Thus, population-based reference intervals may be useful for monitoring ADAMTS13 antigenicity and activity, but not for vWF, which displays high individuality. These findings should be considered when determining the reference interval and other clinical variables associated with ADAMTS13 and vWF levels

Investigation of Toll-like Receptor-2, -3 and -4 Gene Expressions in Larynx Squamous Cell Carcinoma

Objective:Despite all the recent advancements, larynx cancer has shown no improvement in survival rates. The aim of this study was to investigate the expressions of toll-like receptor (TLR)-2, -3, and -4 genes, and determine any relationships with the histopathologic characteristics of the disease.Methods:This retrospective study included 50 subjects who underwent total or partial laryngectomy with an open surgical method for larynx squamous cell carcinoma. Measurements of TLRs-2, -3, and -4 expression values were taken with quantitative real time-polymerase chain reaction in normal tissue and tumor tissue samples of the patients.Results:Evaluations were made of TLR-2, -3, and -4 mRNA expressions according to 2-ΔΔCT calculations in 50 subjects with larynx cancer. When the tumor tissue was compared with the healthy tissue from the same subjects, reductions were determined in TLR expression in 86%, 84%, and 82%, respectively. This reduction in each gene expression was statistically significant (p<0.001). No statistically significant correlation was determined between the change in TLR-2, -3, and -4 expression and the histopathologic characteristics of the disease.Conclusion:The data obtained in this study demonstrated that TLR-2, -3, and -4 expressions were reduced in larynx squamous cell cancer. The results of further studies targeting these genes would be useful in the diagnosis and treatment of the disease

Yeni medyanın toplumsal yansımaları

Yeni medya, hayatımızın her alanında etkisini gösteren ve değiştiren bir olgu haline gelmiştir. Günümüzde insanlar, haberlerini, bilgilerini ve iletişimlerini yeni medya araçları aracılığıyla alıp vermektedirler. Bu araçlar, çok çeşitli işlevleri yerine getirerek kullanıcılarına hız, çeşitlilik, çok seslilik, derinlik, yeni katmanlar, kolaylıklar ve çeşitli seviyelerde iletişim imkanları sunmaktadır. Ancak bu avantajların yanı sıra, yeni medya araçları beraberinde çeşitli sorunları da getirmektedir. Özellikle sosyal medya platformları, kişisel bilgilerin paylaşımı, zorbalık, nefret söylemi ve özel hayatın ihlali gibi güvenlik sorunlarını da beraberinde getirmektedir. Bunun yanı sıra, sosyal medya üzerinden yayılan yanlış bilgiler, manipülasyon ve sahte haberler, hakikatin Önemsizleşmesi gibi sorunları da ortaya çıkarmaktadır..

Combining the Liu-type estimator and the principal component regression estimator

In this study a new two-parameter estimator which includes the ordinary least squares, the principal components regression (PCR) and the Liu-type estimator is proposed. Conditions for the superiority of this new estimator over the PCR, r-k class estimator and Liu-type estimator are derived. Furthermore the performance of this estimator is compared with the other estimators in different conditions with simulation studies

Binary particle swarm optimization as a detection tool for influential subsets in linear regression

An influential observation is any point that has a huge effect on the coefficients of a regression line fitting the data. The presence of such observations in the data set reduces the sensitivity and validity of the statistical analysis. In the literature there are many methods used for identifying influential observations. However, many of those methods are highly influenced by masking and swamping effects and require distributional assumptions. Especially in the presence of influential subsets most of these methods are insufficient to detect these observations. This study aims to develop a new diagnostic tool for identifying influential observations using the meta-heuristic binary particle swarm optimization algorithm. This proposed approach does not require any distributional assumptions and also not affected by masking and swamping effects as the known methods. The performance of the proposed method is analyzed via simulations and real data set applications

A novel method as a diagnostic tool for the detection of influential observations in the Cox proportional hazards model

It is important that the process of studying and modelling the prognosis of disability should be conducted using time-to-event data, as the dynamic nature of disability could cause intervention on the modifiable (prognostic) factors, thus changing the course to a more favourable outcome. In disability research, the Cox PH model is frequently used to identify prognostic factors for the life expectancy of people with disabilities and to evaluate the treatment effects on the time to event. Accurate detection of influential observations is an important factor when fitting the Cox PH model, as influential observations in the Cox PH model can cause model misspecification, inaccurately determined factors, missed valuable biological information and/or violation of the proportional hazard assumption. In this paper, a novel multiple case detection method for influential observations is recommended in the Cox model. The aim of the paper is to inform clinicians and researchers who use the Cox PH model for describing the survival time as a function of multiple prognostic factors, regarding the importance of the detection of influential observations that can lead to misleading conclusions if they are present in the data set. The efficiency of the proposed method is presented through the real dataset. Additionally, in the specific case of North Cyprus, the aim is emphasize the importance of survival modelling studies that determine the prognostic factors affecting the lives of people with disabilities, to improve life quality and to develop a plan for healthier and higher quality life styles programmes for people with disabilities. As a first step, it is recommended that a system of database records of disabilities should be established and maintained by the government to raise public awareness. © 2018, Springer Science+Business Media B.V., part of Springer Nature