Linear Mixed-effects Model Analysis Research Articles

Short-term modifications of mycorrhizal fungi, glomalin and soil attributes in a tropical agroforestry

Arbuscular mycorrhizal fungi (AMF) community and the Glomalin-related soil protein (GRSP) they produce plays important roles in maintaining soil ecosystem functions, promoting ecological restoration, and are important for monitoring changes in soil health from land use change. This research addressed the subtle modifications of AMF and GRSP in different land use types and their association with soil properties. Our objectives were: 1) to assess land use effects on AMF spore density, diversity, and composition besides glomalin fractions (EEG, easily extracted GRSP; TG, total GRSP), and 2) to quantify the relationships between glomalin, AMF community metrics, soil organic carbon (SOC), and key soil quality parameters. Soils were collected in the dry and rainy seasons of 2018 under five land uses, including: three types of agroforestry systems (AS1, AS2 and AS3), an unmanaged pasture and a secondary forest in the state of Rio de Janeiro, Brazil. Linear mixed-effects model and multivariate analyses showed that land uses had influenced the AMF community, meanly at the family level. On the other hand, seasonality has not proved to be an essential factor that modulates the changes of the AMF community and glomalin production. The management practices had influenced AMF sporulation and the number of total species in agroforestry systems. Glomalin is a potential contributor for SOC, mainly in agroforestry systems and pasture plots. Moreover, we found a correlation between the AMF community and key soil parameters. For example, most of the AMF families and spore density were positively correlated with the stability of soil aggregates and SOC. Our findings shed light on that land-use change can shift the AMF community, glomalin and their relationship to key soil quality parameters. Moreover, the adoption of agroforestry systems indicates maintenance of biodiversity and other soil quality parameters with future implications for their use to recover degraded areas.

Emotional availability in dyads of nursing aide - resident with dementia: Old tool, new perspective.

This study examined the emotional availability of nursing aide-resident with dementia dyads in a long-term care-facility. Emotional availability refers to the nursing aide's sensitivity toward the resident, structuring their interactions in a non-intrusive and non-hostile manner and the resident's responsiveness to and involvement of the nursing aide. The study evaluated the reciprocity in the emotional availability of nursing aides and the residents and examined whether emotional availability varies with the level of difficulty of taking care of the residents and with the context of the interaction. The study was conducted in three wards in one long-term care-facility. Twenty nursing aides and 40 residents took part in the study. Each nursing aide was videotaped during feeding, structured and unstructured interactions, with two residents, one that was nominated by the head nurse as difficult to take care of and one that was nominated as easy to take care of. The interactions were coded using the emotional availability scales. Linear mixed-effect model analyses indicated that higher emotional availability of nursing aides was related to higher emotional availability of the residents. Nursing aides' emotional availability did not vary between "difficult" and "easy" residents or across the three interaction contexts. "Difficult" residents involved their nursing aides less than "easy" residents. The study documented the reciprocal nature of the interaction between nursing aides and residents with dementia. It suggests that nursing aides have an important role in promoting residents' responsiveness and involvement.

WOOD CHEMICAL COMPONENTS AND DECAY RESISTANCE OF FOUR COMMON MONGOLIAN SOFTWOODS

To utilize wood resources in Mongolia, amounts of wood chemical components (hot-water extracts, 1% NaOH extracts, ethanol-toluene extracts, holocellulose, -, -, and -cellulose, Klason lignin, and ash) were determined in four common Mongolian softwoods, Pinus sylvestris, Pinus sibirica, Picea obovata, and Larix sibirica. In addition, decay resistance of heartwood was evaluated against a white-rot fungusTrametes versicolor, and a brown-rot fungusFormitopsis palustris. Among the four species, heartwood of Larix sibiricawas chemically characterized by higher amounts of hot-water and 1% NaOH extracts, and lower amounts of holocellulose and Klason lignin. These characteristics may be related to thepresence of arabinogalactan which is easily extracted with cold water. Mean mass loss in each softwood ranged from 6.9% to 28.1% in white-rot fungus, and from 24.8% to 48.3% in brown-rot fungus. Among four species, Pinus sibiricashowed the highest decay resistance against both fungi. By the linear mixed-effects model analysis, negative relationships were found between mass loss and amounts of extracts in heartwood, suggesting that heartwood having larger amounts of extracts showed higher natural decay durability.

The association of social capital with depression and quality of life in school-aged children

Social capital is an important factor that affects mental health. The purpose of this study was to examine the relationship between social capital and depression and between social capital and quality of life (QoL) in children in elementary and junior high school and to examine how this relationship differs in relevant patterns at both the individual- and school-level. The study was conducted in all elementary and junior high schools in a single municipality; the subjects consisted of 3,722 elementary school and 3,987 junior high school students (aged from 9 to 15). A multilevel linear mixed effect model analysis revealed that all three subscales of social capital were associated with depression and QoL at the individual-level: The school social capital at the individual-level showed the strongest association with depression and QoL. We also found that some of social capital at the school-level was associated with depression and QoL. An interactive effect was observed between educational stage (elementary and junior high) and some of social capital subscales. Specifically, the inverse association between school social capital and depression was stronger among the junior high students, while the positive association between school and neighborhood social capital and QoL was stronger among the elementary students. These interactions suggest that social capital impacts depression and QoL differently in elementary and junior high students. These findings suggest that the degree of association of social capital domains differs in mental health among the educational stage.

Cognitive Changes in Older Adults Following a Stepped Care Intervention for Late-life Depression

ObjectivesVulnerable older adults, such as physically impaired or care-dependent individuals, are vastly underrepresented in psychotherapy research. Improving their inclusion in randomized controlled trials is necessary to determine the effectiveness of psychotherapy in this population. This study is the first to systematically evaluate strategies to recruit home-living vulnerable older adults with clinically significant depression into a large randomized controlled psychotherapy trial. Potential participants were approached directly (self-referral) or via cooperation with gatekeepers (gatekeeper-referral).MethodsThe initiator of the first contact with the study team and successful recruitment strategies were recorded. Referral strategies were compared with respect to number of inquiries and inclusion rates; study personnel’s time investment; and participant characteristics (sociodemographics, functional and cognitive status, depression and anxiety scores).ResultsMost of the N=197 participants were included via gatekeeper-referral (80.5%, 95%CI=[74.9%,86.1%], but time investment for gatekeeper-referrals was five times higher than for self-referral by media reports. Clinical psychologists and medical practitioners referred the largest proportion of participants (32.3% each) and referral by medical practitioners led to highest inclusion rates (55.6%; χ²(3)=8.964, p<.05). Most participants were referred from a hospital setting (50.3%), whereas referral numbers by medical practices were low (15.9%). Participants who initiated the first contact themselves had higher inclusion rates and were less functionally and cognitively impaired.ConclusionsIncluding home-living vulnerable older adults into psychotherapy trials requires simultaneous implementation of diverse recruitment strategies. Medical practitioners and psychologists, especially in hospitals, are the most effective recruitment strategy, but self-referral via media is most cost-efficient in terms of time investment.

Cognitive Changes in Older Adults Following a Stepped Care Intervention for Late-life Depression

Older adults with depression may manifest cognitive decline and treating depression may maintain or improve cognition. However, cognitive outcomes could be overlooked in non-pharmacological interventions for depression. This analysis investigated cognitive changes in a stepped-care intervention (Clinical Trial ID: NCT03593889) and the potential association with individual depressive symptom change. The community-dwelling older adults at risk of or with depressive symptoms without significant cognitive impairment (n=802) were assigned to intervention group (n=644) and control group (n=138). Depressive symptoms and cognitive functions were measured using Patient Health Questionnaire-9 and Cognitive Montreal Assessment-5 minutes protocol, respectively. Paired-t-Test showed significant improvements in overall cognition and attention in both intervention and control groups, but the improvements of language fluency (Intervention: MD=-0.51 p<0.01; control: MD=0.14, p=0.500) and orientation (Intervention: MD=-0.22 p<0.05; control: MD=-0.11, p=0.229) only displayed in intervention group. As control group had better cognition at baseline, linear mixed-effects model analysis was used to compare between-group difference. Intervention group had no significant cognitive improvement after adjusting the covariates but a potential improvement in language fluency (Coef. =0.442, SE=0.247, p=0.074). A linear regression analysis in intervention group indicated that reduction of concentration problem (β=0.106, p<0.05) and retardedness (β=0.117, p<0.01) under the symptomatology of depression were associated with the improvement of language fluency. In this group of older persons without significant cognitive impairment, there is no clear evidence of global cognitive benefits in a stepped care depression intervention, although there may be improvements in certain cognitive domains, which may be related to improvements in cognitive aspects of depression.

SpaVerb-WN—A megastudy of naming times for 4562 Spanish verbs: Effects of psycholinguistic and motor content variables

Several studies have been carried out in various languages to explore the role of the main psycholinguistic variables in word naming, mainly in nouns. However, reading of verbs has not been explored to the same extent, despite the differences that have been found between the processing of nouns and verbs. To reduce this research gap, we present here SpaVerb-WN, a megastudy of word naming in Spanish, with response times (RT) for 4562 verbs. RT were obtained from at least 20 healthy adult participants in a reading-aloud task. Several research questions on the role of syllable frequency, word length, neighbourhood, frequency, age of acquisition (AoA), and the novel variable ‘motor content’ in verb naming were also examined. Linear mixed-effects model analyses indicated that (1) RT increase in with increasing word length and with decreasing neighbourhood size, (2) syllable frequency does not show a significant effect on RT, (3) AoA mediates the effect of motor content, with a positive slope of motor content at low AoA scores and a negative slope at high AoA scores, and (4) there is an interaction between word frequency and AoA, in which the AoA effect for low-frequency verbs gradually decreases as frequency increases. The results are discussed in relation to existing evidence and in the context of the consistency of the spelling–sound mappings in Spanish.

Effects of lower limb light-weight wearable resistance on running biomechanics

Wearable resistance allows individualized loading for sport specific movements and can lead to specific strength adaptations benefiting the athlete. The objective was to determine biomechanical changes during running with lower limb light-weight wearable resistance. Fourteen participants (age: 28 ± 4 years; height: 180 ± 8 cm; body mass: 77 ± 6 kg) wore shorts and calf sleeves of a compression suit allowing attachment of light loads. Participants completed four times two mins 20-m over-ground shuttle running bouts at 3.3 m*s−1 alternated by three mins rest. The first running bout was unloaded and the other three bouts were under randomised loaded conditions (1%, 3% and 5% additional loading of the individual body mass). 3D motion cameras and force plates recorded kinematic and kinetic data at the midpoint of each 20-m shuttle. Friedman-test for repeated measures and linear mixed effect model analysis were used to determine differences between the loading conditions (α = 0.05). Increased peak vertical ground reaction force (2.7 N/kg to 2.74 N/kg), ground contact time (0.20 s to 0.21 s) and decreased step length (1.49 m to 1.45 m) were found with additional 5 % body mass loading compared to unloaded running (0.001 > p < 0.007). Marginally more knee flexion and hip extension and less plantarflexion was seen with higher loading. Differences in the assessed parameters were present between each loading condition but accompanied by subject variability. Further studies, also examining long term effects, should be conducted to further inform use of this training tool.

Low‐dose lithium treatment of behavioral complications in Alzheimer’s disease: Lit‐AD randomized clinical trial

AbstractBackgroundTo evaluate low‐dose lithium treatment of agitation in Alzheimer’s disease (AD).MethodIn a four‐site trial, patients with AD and agitation/aggression on the Neuropsychiatric Inventory (NPI) were randomized, double‐blind, to lithium carbonate 150‐600 mg daily or placebo for 12 weeks. Primary efficacy outcome was change in NPI agitation/aggression; secondary efficacy outcome was treatment response defined by 30% reduction in NPI combined score for agitation/aggression plus psychosis and a Clinical Global Impression (CGI) score of much or very much improved. Somatic, cognitive, metabolic, and neurological side effects were assessed.ResultFifty‐eight of 77 patients (75.3%) completed the trial. In linear mixed effects model analyses, lithium did not differ from placebo in agitation/aggression change scores. Proportion of responders was 31.6% on lithium and 17.9% on placebo (χ2=1.26, p=0.26). Moderate or marked improvement on global CGI change, which incorporated behavior, cognition, and function, was greater on lithium (10/38=36.8%) than placebo (0/39=0%, Fisher’s exact test p&lt;0.001). In exploratory analyses, improvement on lithium was greater than placebo on NPI delusions and irritability/lability (p’s&lt;0.05). Lithium showed greater reduction than placebo in patients with high Young Mania Rating Scale scores (β=5.06; 95%CI, 1.18 to 8.94, p=0.01). Oral dose and serum lithium levels demonstrated similar associations with efficacy outcomes. Lithium did not differ significantly from placebo on any safety outcome.ConclusionLow dose lithium was not efficacious in treating agitation but was associated with global clinical improvement and excellent safety. A larger trial may be warranted with precision pharmacological targeting of likely lithium‐responsive behavioral symptoms that overlap with mania.

Serum uric acid level is associated with an increase in systolic blood pressure over time in female subjects: Linear mixed-effects model analyses.

Whether hyperuricemia is a true risk factor for elevated blood pressure (BP) is controversial, and the sex-specific effects of serum uric acid (SUA) on BP during a follow-up period remain unclear. We investigated whether the association of SUA level with systolic or diastolic BP during a 10-year period differs by sex in a Japanese general population of individuals who received annual health examinations (n = 28,990). After exclusion of subjects who had no BP or SUA data at baseline, a total of 22,994 subjects (male/female: 14,603/8391, age: 47 ± 11 years) were recruited. After adjustment for age; body mass index; BP; SUA level; use of drugs for hyperuricemia and hypertension; diagnosis of diabetes mellitus, dyslipidemia, and chronic kidney disease; family history of hypertension; habits of current smoking and alcohol consumption at baseline; the duration of the observation period; and the interaction between each covariate and the duration of the observation period indicated a significant association of SUA level with change in systolic or diastolic BP over time. There was a significant interaction between sex and SUA level for the change in systolic BP (P = 0.003) but not the change in diastolic BP (P = 0.081). The SUA level at baseline (per 1 mg/dL) was significantly associated with a change in systolic BP over time in females (estimate: 0.073 mmHg/year, P = 0.003) but not in males (estimate: 0.020 mmHg/year, P = 0.160). In conclusion, a high SUA level at baseline is significantly associated with an increase in systolic BP over time in female individuals but not in male individuals.

Influence of safety climate on risk tolerance and risk-taking behavior: A cross-cultural examination

Although there are growing number of studies that investigate the influence of safety climate on safety outcomes, the relationship between safety climate and individual risk-taking behavior remains unknown. This study leverages survey data from 11,811 construction workers from 19 countries to empirically validate the associations between safety climate, risk tolerance, and risk-taking decisions in the workplace using linear-mixed effects model analysis. Results showed that safety climate has a significantly negative relationship with risk tolerance. Furthermore, safety climate also has a negative relationship with risk-taking decisions, which is independent of respective risk tolerance levels. These results show that safety climate can reduce risk tolerance and promote more risk-averse decision-making at work. The consistency of these results across diverse cultures suggests that multi-national organizations can foster a consistent safety culture where operational rules are followed, and risks are avoided. Future research is suggested to validate these findings and explore how individual organizational policies and interventions influence safety climate and risk-based decision making.

Effects of a group-based lifestyle medicine for depression: A pilot randomized controlled trial.

Given the growing evidence that a range of lifestyle factors are involved in the etiology of depression, a ‘lifestyle medicine’ approach can be potentially safe and cost-effective to prevent or treat depression. To examine the effects and acceptability of a group-based, integrative lifestyle medicine intervention as a standalone treatment for managing depressive symptoms, a pilot randomized controlled trial (RCT) was conducted in a Chinese adult population in 2018. Participants (n = 31) with PHQ-9 score above the cut-off of ≥ 10, which was indicative of moderate to severe depression, were recruited from the general community in Hong Kong and randomly assigned to lifestyle medicine group (LM group) or care-as-usual group (CAU group) in a ratio of 1:1. Participants in the LM group received 2-hour group sessions once per week for six consecutive weeks, which covered diet, exercise, mindfulness, psychoeducation, and sleep management. Linear mixed-effects model analyses showed that the LM group had a significant reduction in PHQ-9 scores compared to the CAU group at immediate posttreatment and 12-week posttreatment follow-up (d = 0.69 and 0.73, respectively). Moreover, there were significantly greater improvements in anxiety, stress, and insomnia symptoms (measured by DASS-21 and ISI) at all time points in the LM group (d = 0.42–1.16). The results suggests that our 6-week group-based, integrative lifestyle intervention program is effective in lowering depressive, anxiety, stress, and insomnia symptoms in the Chinese population. Further studies in clinical populations with a larger sample size and longer follow-up are warranted.

Combining Heat Stress with Pre-Existing Drought Exacerbated the Effects on Chlorophyll Fluorescence Rise Kinetics in Four Contrasting Plant Species.

Although drought and high temperature are two main factors affecting crop productivity and forest vegetation dynamics in many areas worldwide, little work has been done to describe the effects of heat combined with pre-existing drought on photochemical function in diverse plant species. This study investigated the biophysical status of photosystem II (PSII) and its dynamic responses under 2-day heat stress during a 2-week drought by measuring the polyphasic chlorophyll fluorescence rise (OJIP) kinetics. This study examined four contrasting species: a C3 crop/grass (wheat), a C4 crop/grass (sorghum), a temperate tree species (Fraxinus chinensis) and a tropical tree species (Radermachera sinica). Principal component analysis showed that the combination of heat and drought deviated from the effect of heat or drought alone. For all four species, a linear mixed-effects model analysis of variance of the OJIP parameters showed that the deviation arose from decreased quantum yield and increased heat dissipation of PSII. The results confirmed, in four contrasting plant species, that heat stress, when combined with pre-existing drought, exacerbated the effects on PSII photochemistry. These findings provide direction to future research and applications of chlorophyll fluorescence rise OJIP kinetics in agriculture and forestry, for facing increasingly more severe intensity and duration of both heat and drought events under climate change.

Brain oxygen extraction fraction mapping in patients with multiple sclerosis

We aimed to demonstrate the feasibility of whole brain oxygen extraction fraction (OEF) mapping for measuring lesion specific and regional OEF abnormalities in multiple sclerosis (MS) patients. In 22 MS patients and 11 healthy controls (HC), OEF and neural tissue susceptibility () maps were computed from MRI multi-echo gradient echo data. In MS patients, 80 chronic active lesions with hyperintense rim on quantitative susceptibility mapping were identified, and the mean OEF and within the rim and core were compared using linear mixed-effect model analysis. The rim showed higher OEF and than the core: relative to their adjacent normal appearing white matter, OEF contrast = −6.6 ± 7.0% vs. −9.8 ± 7.8% (p < 0.001) and contrast = 33.9 ± 20.3 ppb vs. 25.7 ± 20.5 ppb (p = 0.017). Between MS and HC, OEF and were compared using a linear regression model in subject-based regions of interest. In the whole brain, compared to HC, MS had lower OEF, 30.4 ± 3.3% vs. 21.4 ± 4.4% (p < 0.001), and higher , −23.7 ± 7.0 ppb vs. −11.3 ± 7.7 ppb (p = 0.018). Our feasibility study suggests that OEF may serve as a useful quantitative marker of tissue oxygen utilization in MS.

Passive Elaborative Cueing of Retrieval ProcessesFollowing Traumatic Brain Injury

ABSTRACT Purpose: Semantic elaboration is a process in which target information is analyzed in relation to content associated in meaning. The goal of the present study was to examine the use of phrasal cues intended to engage elaborative processes theorized to bolster cognitive performance. Methods: Twenty-two individuals with a history of traumatic brain injury (TBI) and twenty-six neurotypical (NT) individuals were studied. Short phrases intended to elicit elaborative encoding were presented prior to the introduction of a prospective memory task and word-stem completions. Phrases embodied one of three conditions: repeated, semantic, or unrelated information. The stem-completion task was presented between each prospective memory task with fixations serving as cues signaling task completion or functioning as distractors. Event-related potentials (ERPs) were captured during the presentation of word-stems. Following the completion of all word-stems, participants were presented with an old/new recognition task. Results: Linear mixed-effects model analyses revealed a significant effect of condition with respect to word retrieval and recognition memory. Captured ERPs revealed neural signatures resembling a P200. Conclusion: Semantic content increased stimulus saliency, facilitated lexical retrieval, and enhanced retention with the latter process revealing use of semantic cues as a more adept rehearsal strategy than repetition.

Climatological and Epidemiological Conditions Are Important Factors Related to the Abundance of blaKPC and Other Antibiotic Resistance Genes (ARGs) in Wastewater Treatment Plants and Their Effluents, in an Endemic Country.

Several physicochemical and season factors have been related to the abundance of antibiotic resistance genes (ARGs) in wastewater treatment plants (WWTPs), considered hotspots of bacterial resistance. However, few studies on the subject have been carried out in tropical countries endemic for resistance mechanisms such as bla KPC. In this study, the occurrence of ARGs, particularly bla KPC, was determined throughout a WWTP, and the factors related to their abundance were explored. In 2017, wastewater samples were taken from a WWTP in Colombia every 15 days for 6 months, and a total of 44 samples were analyzed by quantitative real-time PCR. sul1, sul2, bla KPC, and ermB were found to be the most prevalent ARGs. A low average reduction of the absolute abundance ARGs in effluent with respect to influent was observed, as well as a greater absolute abundance of ARGs in the WWTP effluent in the rainy season. Factors such as temperature, pH, oxygen, total organic carbon (TOC), chemical oxygen demand (COD), and precipitation were significantly correlated with the absolute abundance of several of the ARGs evaluated. A generalized linear mixed-effects model analysis showed that dissolved oxygen and precipitation in the sampling day were important factors related to the absolute concentration of bla KPC over time. In conclusion, the abundance of ARGs in the WWTP could be influenced by endemic conditions and physicochemical and climatological parameters. Therefore, it is necessary to continuously monitor clinical relevant genes in WWTPs from different global regions, even more so in low-income countries where sewage treatment is limited.

Validity of the Aktibipo Self-rating Questionnaire for the Digital Self-assessment of Mood and Relapse Detection in Patients With Bipolar Disorder: Instrument Validation Study.

BackgroundSelf-reported mood is a valuable clinical data source regarding disease state and course in patients with mood disorders. However, validated, quick, and scalable digital self-report measures that can also detect relapse are still not available for clinical care.ObjectiveIn this study, we aim to validate the newly developed ASERT (Aktibipo Self-rating) questionnaire—a 10-item, mobile app–based, self-report mood questionnaire consisting of 4 depression, 4 mania, and 2 nonspecific symptom items, each with 5 possible answers. The validation data set is a subset of the ongoing observational longitudinal AKTIBIPO400 study for the long-term monitoring of mood and activity (via actigraphy) in patients with bipolar disorder (BD). Patients with confirmed BD are included and monitored with weekly ASERT questionnaires and monthly clinical scales (Montgomery-Åsberg Depression Rating Scale [MADRS] and Young Mania Rating Scale [YMRS]).MethodsThe content validity of the ASERT questionnaire was assessed using principal component analysis, and the Cronbach α was used to assess the internal consistency of each factor. The convergent validity of the depressive or manic items of the ASERT questionnaire with the MADRS and YMRS, respectively, was assessed using a linear mixed-effects model and linear correlation analyses. In addition, we investigated the capability of the ASERT questionnaire to distinguish relapse (YMRS≥15 and MADRS≥15) from a nonrelapse (interepisode) state (YMRS<15 and MADRS<15) using a logistic mixed-effects model.ResultsA total of 99 patients with BD were included in this study (follow-up: mean 754 days, SD 266) and completed an average of 78.1% (SD 18.3%) of the requested ASERT assessments (completion time for the 10 ASERT questions: median 24.0 seconds) across all patients in this study. The ASERT depression items were highly associated with MADRS total scores (P<.001; bootstrap). Similarly, ASERT mania items were highly associated with YMRS total scores (P<.001; bootstrap). Furthermore, the logistic mixed-effects regression model for scale-based relapse detection showed high detection accuracy in a repeated holdout validation for both depression (accuracy=85%; sensitivity=69.9%; specificity=88.4%; area under the receiver operating characteristic curve=0.880) and mania (accuracy=87.5%; sensitivity=64.9%; specificity=89.9%; area under the receiver operating characteristic curve=0.844).ConclusionsThe ASERT questionnaire is a quick and acceptable mood monitoring tool that is administered via a smartphone app. The questionnaire has a good capability to detect the worsening of clinical symptoms in a long-term monitoring scenario.

Drug response hysteresis in the concentration-QTc analysis of early clinical trials

ABSTRACT According to the International Conference on Harmonisation E14 Q&As R3, concentration-QTc analysis can serve as an alternative to the by-time-point analysis or intersection-union test as the primary basis for decisions to classify the QTc risk of a drug. In a recent scientific white paper on concentration-QTc analysis, a pre-specified linear mixed effect model was suggested to study a QTc prolongation effect. The model assumes a direct time-concordant relationship (direct effect) between QTc interval and drug-concentrations. In the case of lagged drug QTc effects, also called ‘hysteresis’, a linear direct effect model may yield a biased QTc estimate. In this work, we estimate the bias of QTc effects via simulations when hysteresis is not accounted for in the linear mixed effect model analysis. Simulations are performed to compare different methods of identifying hysteresis when two physiologically plausible QT drug mechanisms are considered. The focus of this paper is to provide hysteresis identification methods and assess the influence of hysteresis in estimating the QT prolongation for most commonly observed QT-Concentration profiles.

The role of production method information on sensory perception of smoked salmon—A mixed-method study from Denmark

Product information is capable of steering the consumers’ expectation formation process. Therefore, this paper aims to investigate whether information on production method influence consumers’ preference and liking of smoked salmon. A consumer test was conducted among 92 consumers to determine liking of the smoked salmon on a 7-point hedonic scale before (blind) and after (informed) receiving information about production method (organic, conventional and wild-caught). Further, two explanatory focus group discussions (n = 5 in each group) were conducted to determine consumers’ belief on production method.A linear mixed-effects model analysis indicated that the consumer overall liking of wild-caught smoked salmon significantly increased after production method information was provided, while regarding organic and conventional smoked salmon no significant difference was noted. Post hoc test indicated that organic smoked salmon was significantly more liked than wild-caught smoked salmon (mean difference ± standard error: 0.652 ± 0.19, p < 0.01) in blind condition, however, between organic and conventional smoked salmon no significant difference was noted (-0.032 ± 0.19, p = 0.983). Further, in informed condition, organic smoked salmon was significantly more liked than conventional smoked salmon (0.50 ± 0.19, p < 0.05), however, between organic and wild-caught smoked salmon no significant difference was noted (0.228 ± 0.19, p = 0.452). Relative importance analysis results suggest that liking of taste was the most important contributor (26.84%) to smoked salmon overall liking (p < 0.05, R2 = 74.17%). Focus group discussion revealed that consumer beliefs related to food safety, animal welfare and sustainability as well as purchasing habits seem to influence smoked salmon preferences.Thus, organic aquaculture sector should focus on promoting consumer beliefs by providing reliable information based on scientific evidences that helps differentiates their products with that of conventional and wild-caught smoked salmon. Future studies might investigate other fish species to better understand the role of product method information on consumer preference and liking of fish.

Variation in bovine leptin gene affects milk fatty acid composition in New Zealand Holstein Friesian × Jersey dairy cows.

Leptin is a protein hormone secreted from white adipose tissue. It regulates food/feed intake, body weight, immune function and reproduction. In our investigation, the polymerase chain reaction (PCR) amplification coupled with single-strand conformational polymorphism (SSCP) analysis was used to reveal variation in bovine leptin gene (LEP) in New Zealand (NZ) Holstein Friesian Jersey (HF J) dairy cows. Subsequent sequence analysis of a 430 bp amplicon spanning the entirety of exon 3 and part of the intron 2 region revealed three variant sequences (, and ) containing a total of five nucleotide substitutions, all of which have been reported previously. Using general linear mixed-effect model analyses, the presence of variant (the most common variant) was associated with a decreased level of C15:1, C18:1 trans-11, C18:1 all trans, C18:2 trans-9, cis-12, C22:0 and C24:0 levels but increased levels of C12:1 and C13:0 iso (). Variant was associated with reduced levels of C6:0, C8:0, C11:0, C13:0 and C20:0 but increased C17:0 iso and C24:0 levels (). Variant was associated with decreased C17:0 iso levels but increased C20:0 () levels. In a genotype model, the genotype was associated with increased levels of C22:0 and C24:0 but decreased C8:0, C10:0, C11:0, C13:0, C15:0 and grouped medium-chain fatty acid (MCFA) levels (). Genotype was found to be associated with decreased levels of C10:0, C11:0, C13:0 and grouped MCFA (). This is the first report of findings of this kind in NZ HF J cows, and they suggest that variation in exon 3 of bovine leptin gene could be explored as a means of decreasing the concentration of saturated fatty acids in milk.