Low Uptake Rates Research Articles

CD36 (SR-B2) as a Target to Treat Lipid Overload-Induced Cardiac Dysfunction

The heart faces the challenge of adjusting the rate of fatty acid uptake to match myocardial demand for energy provision at any given moment, avoiding both too low uptake rates, which could elicit an energy deficit, and too high uptake rates, which pose the risk of excess lipid accumulation and lipotoxicity. The transmembrane glycoprotein cluster of differentiation 36 (CD36), a scavenger receptor (B2), serves many functions in lipid metabolism and signaling. In the heart, CD36 is the main sarcolemmal lipid transporter involved in the rate-limiting kinetic step in cardiac lipid utilization. The cellular fatty acid uptake rate is determined by the presence of CD36 at the cell surface, which is regulated by subcellular vesicular recycling from endosomes to the sarcolemma. CD36 has been implicated in dysregulated fatty acid and lipid metabolism in pathophysiological conditions, particularly high-fat diet-induced insulin resistance and diabetic cardiomyopathy. Thus, in conditions of chronic lipid overload, high levels of CD36 are moved to the sarcolemma, setting the heart on a route towards increased lipid uptake, excessive lipid accumulation, insulin resistance, and eventually contractile dysfunction. Insight into the subcellular trafficking machinery of CD36 will provide novel targets to treat the lipid-overloaded heart. A screen for CD36-dedicated trafficking proteins found that vacuolar-type H+-ATPase and specific vesicle-associated membrane proteins, among others, were uniquely involved in CD36 recycling. Preliminary data suggest that these proteins may offer clues on how to manipulate myocardial lipid uptake, and thus could be promising targets for metabolic intervention therapy to treat the failing heart.

Mammography uptake among the female staff of King Saud University.

Background:Breast cancer is having a major impact on women's health worldwide. Early detection is the best defense against the associated morbidity and mortality of the disease.Objectives:To assess the level of mammography uptake among working Saudi women and identify the obstacles and barriers that negatively affect it. In addition, to identify the most effective sources of breast-cancer-related information and early detection screening.Method:We conducted a cross-sectional study of women employees of King Saud University aged 40 years and above on March–May 2015 using a self-report questionnaire.Results:A total of 229 participants were recruited from the female staff of King Saud University. Of the participants, 34% were aged 41 years or above, approximately 66% were married, 53.3% had a bachelor's degree, and 61.1% worked as administrators; further, 64.6% had a history of breastfeeding. The rate of mammography uptake was 51.5%. Univariate logistic regression indicated that age, education, and being single predict the rate of mammography uptake. However, multivariate logistic regression indicated that earlier age significantly predicts a higher risk of a low rate of mammography uptake. The main obstacle negatively affecting mammography uptake was ineligible criteria (21.8%). The main sources of information regarding breast cancer were awareness campaigns and television and radio (45.4% and 43.7%, respectively).Conclusion:The participants' rate of mammography uptake, awareness of mammograms, the risk factors, and signs of breast cancer were low. To improve breast-cancer mortality rates in Saudi Arabia, earlier detection of breast cancer through increasing awareness of mammograms is of paramount importance.

Expression of sperm-specific glyceraldehyde-3-phosphate dehydrogenase in melanoma cells changes their energy metabolism

The somatic isoform of the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH; EC1.2.1.12) is involved in such crucial for cancer cells development pathways as induction of apoptosis and glycolytic regulation. At the same time, sperm-specific isoform (GAPDHS) does not exhibit all the same functions as somatic enzyme. The expression of sperm-specific GAPDH without N-terminal domain in some melanoma cells along with somatic isoenzyme, shown in our previous work, has led to the proposal of this unusual enzyme's possible role in regulation of cancer cells glycolysis. In the presented work we have tested production of GAPDHS in 13 additional melanoma cell lines by immunoblotting. We have also gathered data on energy metabolism in 5 selected cell lines by evaluation of glucose uptake and lactate production in differing conditions. We have demonstrated that in standard cultivation media glucose uptake by MelP cells, producing substantial amounts of GAPDHS protein was higher than in MelKor cells, producing lesser amounts of GAPDHS. All other analyzed cell lines that do not produce GAPDHS (MelMS, MelSi and Malme3M) had even a lower glucose uptake rate.

A Mixed-Method Study Examining Cancer Screening Uptake among South Asian Ethnic Minorities in Hong Kong

Objective:Utilization of cancer screening is an effective means of cancer prevention. However, South Asian ethnic minorities in Western countries are reported to face barriers in cancer screening utilization, resulting in a low screening uptake by these individuals. The purpose of this mixed-method study is to assess the uptake rate of cancer screening among South Asian ethnic minorities in the Chinese Society of Hong Kong and to examine the factors affecting their participation in cancer screening.Methods:This study utilized a sequential mixed-method design, involving two phases. Following the implementation of a self-report survey among South Asian participants via an author-developed questionnaire with 1547 participants in Phase 1, a focus group interview was conducted with 34 participants in Phase 2 to assess the barriers to screening utilization. Convenience sampling was adopted to recruit participants at South Asian community centers in Phase 1, whereas purposive sampling was used for recruiting participants in Phase 2.Results:The findings revealed a low (<40%) uptake rate of cancer screening among the participants. Health illiteracy, language barrier, limited access to health information and screening services, and cultural issues were the major barriers to their cancer screening utilization.Conclusions:Our findings provided valuable information for both policymakers and health professionals to better understand the needs of ethnic minorities in Hong Kong. As cancer death rates can be lowered by early detection and primary preventive measures, health professionals should focus on the development of culture-specific interventions. Similarly, training the community health workers can strengthen the primary care system in enhancing knowledge on cancer, its prevention, and access to cancer screening services among local ethnic minorities.

Assessment of knowledge, practices and associated factors toward prevention of hepatitis B virus infection among students of medicine and health sciences in Debre Berhan University, NorthShewa, Ethiopia: A cross-sectional study

BackgroundHepatitis B virus (HBV) infection is one of the major public health problems in the world. HBV can be transmitted from one infected person to another easily by different mechanism. In our institution, the knowledge and practices of trainees in the health professions towards occupational risk of HBV was not investigated. Thus, the aim of this study was to assess the knowledge and practices toward prevention of HBV infection and identify predictors among students of medicine and health sciences. MethodsA cross-sectional study was undertaken. A total of 355 students of healthcare professions were approached for the study using a simple random sampling technique. Data towards HBV was assessed by using a pre validated self-administered structured questionnaire and analyzed by using SPSS version 22.0. Bivariable and multivariable logistic regression was used to identify associated factors with knowledgeand practice. ResultOut of 422 distributed questionnaires, 355 were returned with a response rate of 84.12%. Majority of the students 268 (75.49%) were in the age group 20–24 and 279 (78.59%) of the respondents were male. Our study showed that the overall knowledge regarding HBV, its mode of transmission and prevention was high 276 [77.75%; 95%CI= (64.43–91.82)]. ConclusionsOur study found that trainees in health profession are at a very high risk of contracting HBV infection during their training owing to the low HBV vaccine uptake rate and high rate of accidental exposure to blood. Thus, we recommend that all students in the health profession should be vaccinated prior to their entry into professional practices.

Cost-effectiveness analysis of antiviral treatment for pregnant women with high viral load to prevent hepatitis B virus vertical transmission.

Vertical transmission of the hepatitis B virus (HBV) is higher in infants born to pregnant women with a higher HBV DNA viral load even if the infants complete both active and passive vaccination. Although antiviral treatment is recommended for pregnant women during the antenatal period to reduce the rate of vertical transmission, most of them decline treatment. A decision tree was made to evaluate the costs and benefits involved when pregnant women either agreed or declined to take antiviral treatment during the antenatal period. The cost-effectiveness price was arrived at by multiplying the reduced vertical transmission rate with expenses of future medical care associated with vertical transmission. From an individual mother's perspective, it was not cost-effective to receive antenatal antiviral treatment given the observed medication price and transmission rate in Singapore. However, the health system asserts that the current price of antiviral treatment is already far below the cost-effectiveness level, even without the Ministry of Health subsidies. Additionally, the awareness and perception of pregnant women also impacted treatment decisions. By analysing the decision-making process, our result explained the current low uptake rates of antenatal antiviral treatment for HBV among pregnant women. We also concluded that from the health system's perspective, it was worth providing subsidies for perinatal antiviral treatment to prevent huge expenses generated in the future by chronic HBV complications.

Indicators of Quality of Clinical Care for Type 2 Diabetes Patients in Primary Health Care Centers in Qatar: A Retrospective Analysis.

Background Despite the high prevalence of type 2 diabetes mellitus in Gulf countries, standards of diabetes care at the primary care level have not been widely studied. Aim To compare the results of diabetes clinical indicators from the American Diabetes Association (ADA) 2017 guidelines to the reference benchmarks in the Behavioral Risk Factor Surveillance System. Materials and Methods A cross-sectional analysis of electronic medical records in 643 randomly selected adult patients with type 2 diabetes was undertaken. A checklist enabled the collection of sociodemographic, clinical, biochemical, and quality measurement data. Data were analyzed using Stata 9.0. The chi-squared test was used to compare two or more proportions. Results There were 643 patients (male = 60.3%; female = 39.7%), and the majority (71.7%) aged between 40 and 64 years. Common comorbidities were dyslipidemia (72.3%), hypertension (70%), obesity (50.1%), and preobesity (overweight) (37.9%). Over 15% were smokers. The most commonly prescribed diabetes medications were metformin (89.9%), dipeptidyl peptidase-4 inhibitors (61.1%), and sulfonylureas (49.3%). Only 35.5% (p < 0.0001) of patients met the reference glycated hemoglobin (HbA1c) cutoff level of 7.0%. The reference level for blood pressure control was met by 70.2% (p < 0.0001) and for low-density lipoprotein cholesterol, 73.8% (p < 0.0001). Albuminuria was present in 39.2%, and very low vitamin D level (<20 ng/ml) in 39.1%. Most patients had annual foot (89.6%, p < 0.0001) and eye (72.3%, p < 0.0001) examinations. Only 39.9% had referrals for dietary counseling, and there were lower rates of referrals and uptake for pneumococcal, influenza, and hepatitis B vaccines. Most (76.2%) did not have screening for depression. Conclusion The majority of the results met the ADA standards, while glycemic control, dietary counseling, and screening for depression were poor in comparison to the standards. Continuing education for clinicians, patient education for self-management, and targeted weight management are recommended.

Uptake of Referrals for Women at High-Risk of Perinatal Depression and the Effectiveness of Interventions to Increase Uptake: A Systematic Review and Meta-Analysis

Background: Low uptake rate of referral after screening will reduce the utility of screening programmes for perinatal depression. However, estimates of the uptake rate among high-risk women who are offered referral varied widely across studies and little is known about the effectiveness of interventions to increase uptake. Therefore, we reviewed available evidence on uptake rate and the effectiveness of interventions to increase uptake. Methods: We did a systematic review and meta-analysis. Pubmed, Web of science, Cochrane Library, Ovid, Embase, CNKI, Wanfang Database, and VIP Databases were searched for studies published before January 13, 2019. To be eligible for inclusion, the studies needed to have information on uptake rate and/or effectiveness of interventions on uptake of referral. Observational studies were used to estimate the pooled uptake rate. We performed meta-regression and subgroup analyses to explore the source of heterogeneity. We did descriptive analyses instead of meta-analyses due to the limitation of the number of experimental studies to evaluate the effectiveness of interventions. The study was registered in the PROSPERO database, number CRD42019138095. Findings: Of 2302 records identified, 38 studies were eligible, including 36 observational studies (with a total of 7918 participants) and two experimental studies (with a total of 598 participants). The pooled uptake rate of referral was 40% (95% confidence interval [CI] 32% to 48%) based on 36 observational studies. Meta-regression and subgroup analyses showed that referral to on-site assessment or treatment (57%, 95%CI 47% to 68%) had a significantly higher uptake rate than referral to mental health service (32%, 95%CI 23% to 41%) (Odds ratio 1·27, 95%CI 1·06 to 1·51). The two experimental studies showed significant improvement in uptake of referral but the quality of the evidence was weak. Interpretation: Three fifths of high-risk women do not take up the referral offers after perinatal depression screening. Referral to on-site assessment and treatment may improve uptake of referral, but as the quality of evidence on interventions to increase uptake was weak. More robust studies are needed, especially in low and middle income countries. Funding: The National Nature Science Foundation of China. Declaration of Interest: We declare no competing interests.

Inequalities in vaccination coverage and differences in follow-up procedures for asylum-seeking children arriving in Wales, UK.

The European Vaccine Action Plan 2015-2020 highlights the importance of reducing inequities and monitoring performance in underserved groups including migrants. However, there are limited data from European countries and policies for catch-up vary by country. Vaccination coverage in accompanied asylum-seeking children aged 5 to 16 years in two dispersal areas of Wales is presented alongside the coverage in the local population. Coverage data for asylum-seeking children were collated locally using asylum seeker nurse records whilst coverage in the local population was calculated using data from the National Community Child Health Database, a repository of data from all local Child Health Systems in Wales. The processes for following up outstanding vaccinations were also collected using a face-to-face questionnaire distributed to lead asylum seeker nurses in each area. As at the date of assessment, 45.6% (67/147) of children dispersed to area one had received all recommended immunisations compared with 62.2% (150/241) dispersed to area two, OR 0.51 (95% CI 0.33-0.79). At both sites the odds of being vaccinated against key vaccine preventable infections were around three times lower if you were an asylum-seeking child, compared with the local population. Similar procedures were in place for new asylum seekers in both dispersal areas. Area one had less resource to follow up missing immunisations, and children did not receive an initial health assessment unlike area two. Verbal history was accepted in area one but not in area two, despite area two having higher vaccine uptake.Conclusion: Asylum-seeking children have low rates of vaccine uptake compared with the general population, although uptake differs depending on dispersal area. Inequalities in vaccination services, such as resource and strategies to improve uptake, need to be considered.What is Known:• The European Vaccine Action Plan 2015-2020 highlights the importance of reducing inequities and monitoring performance in underserved groups including migrants.• Limited data from European countries suggest inequalities in uptake of immunisations in migrants compared with the local population. Policies for catching up immunisations vary by country.What is New:• Despite national policy for vaccination of migrants with missing or incomplete vaccination history in Wales, this work suggests vaccination coverage in asylum-seeking children is not equitable with the local population.• Vaccination coverage in asylum-seeking children dispersed to different areas of Wales also varies, and this may be associated with differences in local catch-up strategies and the ability to follow national policy. Resource and strategies to maintain engagement with health services play an important role in increasing vaccine uptake in underserved groups.

Randomized controlled trial: Flexible sigmoidoscopy as an adjunct to faecal occult blood testing in population screening.

Flexible sigmoidoscopy screening at around age 60 can reduce colorectal cancer incidence. Insufficient evidence exists on flexible sigmoidoscopy at age 60 in a population being offered biennial faecal occult blood test screening from age 50. This randomized controlled trial assessed if flexible sigmoidoscopy would be an effective adjunct to faecal occult blood test. In the Scottish Bowel Screening Programme between June 2014 and December 2015, 51,769 individuals were randomized to be offered flexible sigmoidoscopy instead of faecal occult blood test at age 60 or to continue faecal occult blood test. Those not accepting flexible sigmoidoscopy and those with normal flexible sigmoidoscopy were offered faecal occult blood test. All with flexible sigmoidoscopy-detected neoplasia or a positive faecal occult blood test result were offered colonoscopy. Overall flexible sigmoidoscopy uptake was 17.8%, higher in men than women, and decreased with increasing deprivation (25.7% in the least to 9.2% in the most deprived quintile). In those who underwent flexible sigmoidoscopy, detection rate for colorectal cancer was 0.13%, for adenoma 7.27%, and for total neoplasia 7.40%. In those who underwent colonoscopy after a positive flexible sigmoidoscopy, detection rate for colorectal cancer was 0.28%, adenoma 8.66%, and total neoplasia 8.83%. On an intention to screen basis, there was no difference in colorectal cancer detection rate between the study and control groups. Adenoma and total neoplasia detection rate were significantly higher in the study group, with odds ratios of 5.95 (95%CI: 4.69-7.56) and 5.10 (95%CI: 4.09-6.35), respectively. In a single screening round at age 60, there was low uptake and neoplasia detection rate. Flexible sigmoidoscopy detected significantly more neoplasia than faecal occult blood test alone.

Variation in uptake of Healthy Start Food Vouchers in the Six Health and Social Care Partnerships

Abstract Background The primary aim of this study was to assess the difference in uptake levels of Healthy Start Food Vouchers, a means tested benefit to afford nutritious food, between 6 Health and Community Partnerships (HSCP) in Greater Glasgow and Clyde (GGC). Our secondary aim was to explore possible reasons for the observed variation. Methods Routinely collected Healthy Start data for the months of August to September 2017 were obtained from the UK Department of Health. Postcode sectors were matched up with their corresponding HSCPs in GGC. Analysis looked for associations between uptake rates and various HSCP area-based characteristics. Results Large variations were observed within GGC. Chi-square test showed a significant association between uptake and HSCP area (P &amp;lt; 0.0005). Trend analysis of uptake with area deprivation (P = 0.001) and resource allocation (P &amp;lt; 0.001) was also significant. Subjective analysis of trend direction suggested that uptake increased with deprivation and resource allocation of the HSCP. Conclusions Significant trends were found and the observed patterns suggested that the relationship between uptake rates and HSCP area is more complex than the geographical characteristics alone. Future studies need to look at the difference in management and awareness of the voucher scheme between Maternity teams in HSCPs. Key messages There is significant variation in the uptake of means tested benefits with some areas having a nearly forty percent of eligible individuals not receiving available support. A qualitative approach is required to determine the causes of low uptake rates of benefits and improve the effectiveness of maternity teams in different areas.

Fusaric acid instigates the invasion of banana by Fusarium oxysporum f. sp. cubense TR4.

Summary Fusaric acid (FSA) is a phytotoxin produced by several Fusarium species and has been associated with plant disease development, although its role is still not well understood.Mutation of key genes in the FSA biosynthetic gene (FUB) cluster in Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4) reduced the FSA production, and resulted in decreased disease symptoms and reduced fungal biomass in the host banana plants.When pretreated with FSA, both banana leaves and pseudostems exhibited increased sensitivity to Foc TR4 invasion. Banana embryogenic cell suspensions (ECSs) treated with FSA exhibited a lower rate of O2 uptake, loss of mitochondrial membrane potential, increased reactive oxygen species (ROS) accumulation, and greater nuclear condensation and cell death. Consistently, transcriptomic analysis of FSA‐treated ECSs showed that FSA may induce plant cell death through regulating the expression of genes involved in mitochondrial functions.The results herein demonstrated that the FSA from Foc TR4 functions as a positive virulence factor and acts at the early stage of the disease development before the appearance of the fungal hyphae in the infected tissues.

Physician-office vs home uptake of colorectal cancer screening using FOBT/FIT among screening-eligible US adults.

BackgroundGuidelines of the American Cancer Society and US Preventive Services Task Force specify that colorectal cancer (CRC) screening using guaiac‐based fecal occult blood test (FOBT)/fecal immunochemical test (FIT) should be done at home. We therefore examined the prevalence and correlates of CRC screening using FOBT/FIT in physicians' office vs at home.MethodsAnalysis of 9493 respondents 50‐75 years old from the Cancer Control Supplement of the 2015 National Health Interview Survey was conducted. Weighted multivariable logistic regression was used to identify the determinants of in‐office vs home use of FOBT/FIT for CRC screening.ResultsOf the overall sample of screening‐eligible adults (n = 9403), only 937 (10.4%) respondents underwent CRC screening using FOBT/FIT within the past year; among this screening population, 279 (28.3%) respondents were screened in‐office. We found that sociodemographic factors alone, not CRC risk factors, determined whether FOBT/FIT would be used in‐office or at home. Hispanics had greater odds of being screened in‐office using FOBT/FIT (aOR: 2.04; 95% CI: 1.05‐3.99). Compared with those 50‐59 years old, respondents 70‐75 years old were less likely to be screened in‐office using FOBT/FIT (aOR: 0.44, 95% CI: 0.25‐0.79). Similarly, individuals residing in the Western region of the country had lower odds of in‐office FOBT/FIT (aOR: 0.26; 95% CI: 0.11‐0.58).ConclusionAmid low overall uptake rates of FOBT/FIT in the United States, in‐physician office testing is high, indicative of a missed opportunity for effective screening and poor adherence of physicians to national guidelines. Sociodemographic factors are determinants of uptake of FOBT/FIT at home or in‐office and should be considered in designing interventions aimed at providers and the general population.

Leaf litter identity alters the timing of lotic nutrient dynamics

Abstract The effects of resource quality on ecosystems can shift through time based on preferential use and elemental needs of biotic consumers. For example, leaf litter decomposition rates are strongly controlled by initial litter quality, where labile litter is processed and depleted more quickly than recalcitrant litters. We examined the effect of this processing continuum on stream nutrient dynamics. We added one of four different litter compositions differing in litter quality (cottonwood [Populus deltoides], labile; sycamore [Platanus occidentalis], recalcitrant; bur oak [Quercus macrocarpa], recalcitrant; and mixed [equivalent mixture of previous three species]) to 12 large (c. 20 m long, with riffle, glide and pool sections) outdoor stream mesocosms to assess the effect of litter species composition on whole‐stream nutrient uptake. Nutrients were dosed once weekly for 8 weeks to measure uptake of NH4–N, NO3–N, and PO4–P. We also measured changes in litter C, N, and P content on days 28 and 56 of the study. Nutrient uptake rates were highly variable, but occasionally very different among litter treatments (c. 5× between highest and lowest uptake rates by species). Uptake rates were generally greatest in cottonwood (labile) streams early in the study. However, during the last 4 weeks of the study, bur oak streams (recalcitrant) took up more nutrients than cottonwood streams, resulting in more cumulative NO3–N uptake in bur oak than in cottonwood streams. Cumulative NO3–N uptake was greater in mixed streams than expected (non‐additive) on two dates of measurement, but was generally additive. Changes in litter nutrient content largely corroborated nutrient uptake patterns, suggesting strong N immobilisation early in the study and some N mineralisation later in the study. P was strongly retained by most litters, but especially bur oak. Nutrient content of litter also largely changed additively, suggesting minimal evidence for non‐additive diversity effects on nutrient source/sink status. Our results demonstrate that litter species identity can have whole‐ecosystem effects on stream nutrient dynamics, with important implications for the form and fate of nutrients exported downstream. Further, diverse litter assemblages may serve as temporal stabilisers of ecosystem processes, such as nutrient sequestration, due to microbial nutrient requirements and differential decomposition rates, or the classic litter processing continuum.

Should pregnant women be charged for non-invasive prenatal screening? Implications for reproductive autonomy and equal access

The introduction of non-invasive prenatal testing (NIPT) in healthcare systems around the world offers an opportunity to reconsider funding policies for prenatal screening. In some countries with universal access healthcare...

59 Male Family Carers’ Perceptions of Formal Support Services, a Meta-ethnography

Abstract Background Family carers provide thousands of hours of unpaid work every year, a third of whom are men, however this group are generally under-represented in research. Comparative studies have shown that male carers experience their caring role differently to female counterparts. Social concepts related to masculinity can help to explain help-seeking behaviours of male carers, as well as their attitudes to accessing outside support. Compared to women carers, men have lower rates of uptake of formal support services. This aim of this review, therefore, was to examine accounts of male carers’ experiences and perceptions of receiving formal support. Methods The study followed a meta-ethnography process starting with a systematic literature search of five electronic databases. The methodological quality of the included studies was evaluated using the McMaster checklist. Using NVivo 12 software, primary qualitative data was analysed and key themes were identified. Results were synthesised using Noblit and Hare’s (1988) process of meta-ethnography, retaining direct quotes from the studies. Results Eighteen studies were included in the final paper. Three main themes were identified: 1) asserting control over the caring role 2) desire to excel in caring role and 3) coping without formal support. Conclusion For the most part, male carers expressed a desire to be competent in their caring role. Perceived loss of control within the caring relationship was a key factor when men had low trust and dissatisfaction with services. Support services that were collaborative, education-based and gender-sensitive were favoured by the men. To engage more male carers, service providers should acknowledge men’s experience and capabilities as well as their wish to stay involved in decision-making around care for their family member. For men over the age of 85 male family carers outnumber females in Ireland (CSO 2016). It is important to understand male carers’ experience to develop more inclusive supports and consequently increase service uptake.

Protein adsorption to poly(ethylenimine)-modified Sepharose FF: VIII: Impacts of surface ion-exchange groups at different polymer grafting densities

Our previous studies on protein adsorption to the anion-exchangers of poly(ethylenimine) (PEI)-grafted Sepharose FF found that both adsorption capacity and uptake rate of bovine serum albumin (BSA) increased greatly when the PEI grafting density reached over a critical ionic capacity (cIC) due to the 3D protein binding and occurrence of “chain delivery” of bound proteins. Moreover, by the investigation on the anion-exchangers of diethylaminoethyl (DEAE)-modified and DEAE-dextran-grafted Sepharose FF, we found the unique role of surface ligand in facilitating protein uptake kinetics on dextran-functionalized anion exchangers as the “transfer station” for the “chain delivery” of bound proteins. However, what would be the contribution of surface ligands on the transport of bound proteins on PEI chains at a wide range across cIC, particularly at the lower IC range where no “chain delivery” was present? We have thus designed this research to answer the question. To this purpose, we fabricated three series of PEI-Sepharose FF resins, one without surface ligand (i.e., FF-PEI) and two with surface DEAE modifications at DEAE coupling densities of 60 and 90 mmol/L (i.e., FF-D60-PEI and FF-D90-PEI), and focused on the role of surface DEAE at different PEI densities in BSA adsorption equilibrium and uptake kinetics in a wide IC range of PEI across cIC (∼600 mmol/L for BSA). It was found that, at low grafting-ligand densities (IC<cIC), both adsorption capacity and uptake rate increased significantly (5–14% and 40–140%, respectively) after adding surface DEAE groups. At IC > cIC, however, both adsorption capacity and uptake rate changed only slightly (<5% and <10%, respectively) by the addition of surface DEAE groups. The results revealed that at IC < cIC, the surface DEAE groups provided the supplement of available binding sites and facilitated the happenings of the “chain delivery” of bound proteins as the “transfer station”, both of which were limited at the low IC range. However, at IC > cIC, the extended flexible PEI chains have already afforded 3D binding space with high accessibility and easy happening of “chain delivery” of bound proteins, so the surface DEAE groups between neighboring PEI chains did not work in assisting the transport of bound proteins. Moreover, when the IC was lower but close to the cIC, the FF-D-PEI resins exhibited higher uptake rates than FF-PEI resins at a similar or even lower IC values. These findings indicate that surface modification of charged groups in PEI-based anion exchangers of low grafting density would be an efficient strategy to fabricate high performance protein ion exchangers.

Multi-Omics Analysis of Fatty Alcohol Production in Engineered Yeasts Saccharomyces cerevisiae and Yarrowia lipolytica.

Fatty alcohols are widely used in various applications within a diverse set of industries, such as the soap and detergent industry, the personal care, and cosmetics industry, as well as the food industry. The total world production of fatty alcohols is over 2 million tons with approximately equal parts derived from fossil oil and from plant oils or animal fats. Due to the environmental impact of these production methods, there is an interest in alternative methods for fatty alcohol production via microbial fermentation using cheap renewable feedstocks. In this study, we aimed to obtain a better understanding of how fatty alcohol biosynthesis impacts the host organism, baker’s yeast Saccharomyces cerevisiae or oleaginous yeast Yarrowia lipolytica. Producing and non-producing strains were compared in growth and nitrogen-depletion cultivation phases. The multi-omics analysis included physiological characterization, transcriptome analysis by RNAseq, 13Cmetabolic flux analysis, and intracellular metabolomics. Both species accumulated fatty alcohols under nitrogen-depletion conditions but not during growth. The fatty alcohol–producing Y. lipolytica strain had a higher fatty alcohol production rate than an analogous S. cerevisiae strain. Nitrogen-depletion phase was associated with lower glucose uptake rates and a decrease in the intracellular concentration of acetyl–CoA in both yeast species, as well as increased organic acid secretion rates in Y. lipolytica. Expression of the fatty alcohol–producing enzyme fatty acyl–CoA reductase alleviated the growth defect caused by deletion of hexadecenal dehydrogenase encoding genes (HFD1 and HFD4) in Y. lipolytica. RNAseq analysis showed that fatty alcohol production triggered a cell wall stress response in S. cerevisiae. RNAseq analysis also showed that both nitrogen-depletion and fatty alcohol production have substantial effects on the expression of transporter encoding genes in Y. lipolytica. In conclusion, through this multi-omics study, we uncovered some effects of fatty alcohol production on the host metabolism. This knowledge can be used as guidance for further strain improvement towards the production of fatty alcohols.

Use of gene knockout to examine serotonergic control of ion uptake in zebrafish reveals the importance of controlling for genetic background: A cautionary tale

Freshwater (FW) fishes inhabit dilute environments and must actively absorb ions in order to counteract diffusive salt loss. Neuroendocrine control of ion uptake in FW fishes is an important feature of ion homeostasis and several important neuroendocrine factors have been identified. The role of serotonin (5-HT), however, has received less attention despite several studies pointing to a role for 5-HT in the control of ion balance. Here, we used a gene knockout approach to elucidate the role of 5-HT in regulating Na+ and Ca2+ uptake rates in larval zebrafish. Tryptophan hydroxylase (TPH) is the rate-limiting step in 5-HT synthesis and we therefore hypothesized that ion uptake rates would be altered in zebrafish larvae carrying knockout mutations in tph genes. We first examined the effect of tph1b knockout (KO) and found that tph1bKO larvae, obtained from Harvard University, had reduced rates of Na+ and Ca2+ uptake compared to wild-type (WT) larvae from our institution (uOttawa WT), lending support to our hypothesis. However, further experiments controlling for differences in genetic background demonstrated that WT larvae from Harvard University (Harvard WT) had lower ion uptake rates than those of uOttawa WT, and that ion uptake rate between Harvard WT and tph1bKO larvae were not significantly different. Therefore, our initial observation that tph1bKO larvae (Harvard source) had reduced ion uptake rates relative to uOttawa WT was a function of genetic background and not of knockout itself. These data provide a cautionary tale of the importance of controlling for genetic background in gene knockout experiments.

Energy metabolism controls phenotypes by protein efficiency and allocation

Cells require energy for growth and maintenance and have evolved to have multiple pathways to produce energy in response to varying conditions. A basic question in this context is how cells organize energy metabolism, which is, however, challenging to elucidate due to its complexity, i.e., the energy-producing pathways overlap with each other and even intertwine with biomass formation pathways. Here, we propose a modeling concept that decomposes energy metabolism into biomass formation and ATP-producing pathways. The latter can be further decomposed into a high-yield and a low-yield pathway. This enables independent estimation of protein efficiency for each pathway. With this concept, we modeled energy metabolism for Escherichia coli and Saccharomyces cerevisiae and found that the high-yield pathway shows lower protein efficiency than the low-yield pathway. Taken together with a fixed protein constraint, we predict overflow metabolism in E. coli and the Crabtree effect in S. cerevisiae, meaning that energy metabolism is sufficient to explain the metabolic switches. The static protein constraint is supported by the findings that protein mass of energy metabolism is conserved across conditions based on absolute proteomics data. This also suggests that enzymes may have decreased saturation or activity at low glucose uptake rates. Finally, our analyses point out three ways to improve growth, i.e., increasing protein allocation to energy metabolism, decreasing ATP demand, or increasing activity for key enzymes.