The Use of the Generalized Linear Model to Assess the Speed and Uniformity of Germination of Corn and Soybean Seeds

The use of seeds with high physiological quality allows rapid growth and establishment of seedlings in the field to be obtained. Therefore, the accuracy of the information obtained during the determination of the physiological quality of seeds is of great importance. The objective was to use generalized linear models, investigating which link function (Probit, Logit and Complementary log-log) is suitable to predict T50 and uniformity during germination of soybean and corn seeds. To perform the experiments, we used seeds from five commercial hybrids and/or cultivars of corn and soybean. The germination speed was calculated by counting the germinated seeds and the results were expressed in the form of proportions. Germination uniformity was calculated by the difference in the times required for germination. The best model was selected according to the criteria of the test of Deviance, AIC and BIC. The Logit model showed accurate results for most cultivars. The evaluation of germination in the form of proportions considering the assumption of binomial response is satisfactory, and the choice of the link function is dependent on the characteristics of each lot and/or species evaluated. The use of this methodology makes it possible to estimate any germination time and uniformity.

Frailty Component Trajectories After Restoration of Kidney Function Among Kidney Transplant Recipients

Frailty is associated with decreased access to kidney transplantation (KT) and poor post-KT outcomes. Little is known about how an acute stressor, like KT, can impact the five physical frailty phenotype (PFP) criteria. We conducted a two-center prospective cohort study (2009-2019) of adult patients undergoing KT. PFP criteria were measured at KT admission, 1 month, 3 months, 6 months, 1 year, and annually thereafter post-KT. We used adjusted mixed effects models with fixed and random effects for person and time to describe repeated measures of continuous criteria components (weight, gait speed, grip strength, activity). We used an adjusted generalized estimating equation to quantify longitudinal, binomial response patterns of exhaustion. Among 1,410 KT recipients (mean age=53) followed for a mean of 1.9 years (IQR=0.1-3.2), 46.8% had low activity, 46.7% weakness, 29.0% exhaustion, 16.1% slowness, and 14.3% unintentional weight loss at KT admission. Among continuous components, weight worsened (0.3lb/month, 95%CI:0.2,0.4), while grip strength (0.09kg/month, 95%CI: 0.07,0.11) and activity (5.8Kcal/month, 95%CI: 3.3, 8.2) improved post-KT; gait speed remained stable (-0.0004s/month, 95%CI: -0.01, 0.0005). Additionally, likelihood of transitioning from being exhausted did not change (OR=1.0, 95%CI: -0.01, 0.0005). Trajectories differed by age, such that improvements were observed among younger recipients (<65 years), but not among older recipients (≥65 years) (p-interactions<0.05). After undergoing a common surgical stressor, KT recipients demonstrated weight gain as well as improvements in strength and activity. Despite benefits of restoration of kidney function, clinicians should consider monitoring KT recipients for persistent weight gain, exhaustion, and slowness post-KT, particularly among older adults.

Saved by Wealth? Income, Wealth, and Self-Perceived Health in Spain during the Financial Crisis

We evaluate the association between the variations in income and wealth, (both aggregate and split between real estate and financial wealth), and self-perceived health in Spain using a longitudinal sample of individuals before and after the financial crisis. We estimated generalized linear mixed models, with a binomial response and a logistic link, for four waves of the Spanish Survey of Household Finances (two before and two after the crisis), adjusting for variables at the family and individual levels. We also controlled for familial and individual heterogeneity and for temporal trends. While an increase in wealth greatly increases the probability of younger individuals reporting better health, this is not the case for older individuals. Decreases in gross wealth are associated with decreases in the probability of declaring good/very good health only in families whose reference person is over 44 years old. We conclude that: (i) not just income but net wealth effects impact on the consequences of income fluctuations on consumption and health assessed, (ii) the composition of individuals’ net wealth may also matter, since they are differently affected by the shocks in the economic crisis, (iii) age plays a significant role and, finally, (iv) individual reactions in terms of consumption and savings, given any level of income and wealth, according to the risk aversions for precautionary idiosyncratic motives, may also need to be considered in order to complete the picture.

Jeffreys-prior penalty, finiteness and shrinkage in binomial-response generalized linear models

Summary Penalization of the likelihood by Jeffreys’ invariant prior, or a positive power thereof, is shown to produce finite-valued maximum penalized likelihood estimates in a broad class of binomial generalized linear models. The class of models includes logistic regression, where the Jeffreys-prior penalty is known additionally to reduce the asymptotic bias of the maximum likelihood estimator, and models with other commonly used link functions, such as probit and log-log. Shrinkage towards equiprobability across observations, relative to the maximum likelihood estimator, is established theoretically and studied through illustrative examples. Some implications of finiteness and shrinkage for inference are discussed, particularly when inference is based on Wald-type procedures. A widely applicable procedure is developed for computation of maximum penalized likelihood estimates, by using repeated maximum likelihood fits with iteratively adjusted binomial responses and totals. These theoretical results and methods underpin the increasingly widespread use of reduced-bias and similarly penalized binomial regression models in many applied fields.

PSXI-31 How is the ingestive behaviour of mid lactating Holstein cows grazing a fescue based pasture under two different defoliation intensities?

An experiment was performed to study the effect of two contrasting defoliation intensities of a fescue based pasture on the ingestive behaviour. Treatments were two grazing intensities: lax treatment (TL) 12 cm and control treatment (TC) 6 cm, with four replicants of 0.3 ha each. The starting of the experiment was determined by the three leaf stage. Twenty-four mid lactating Holstein cows were blocked according to parity, body weight, body condition score and calving date. Each plot was grazed by three cows during as many days as necessary until the defoliation height of each treatment was achieved (TL: 6 d; TC: 8 d). The pasture mass was 2530 ± 180 kgDM/ha and animals had access from 8:00 to 16:00. Each cow received 7.4 kgDM of supplementation (17% Crude Protein; 2.81 Mcal/kgDM). After PM milking (17:00 h) animals remained separated in 8 pens, where they received 5.5 kgDM in individual troughs. The remaining supplement was provided in the AM milking (05:00 h). During the access to the pasture, grazing and ruminating times and bites rate (BT; bites/minute) were determined every 5 minutes by visual observation at the beginning, middle and end of the experiment. Daily ruminating (DR) was also logged by electronic recorders in 2h periods (Heatime®HR, SCR Dairy). The PROC GLIMMIX of SAS (SAS 9.2, 2010) with a binomial response distribution and with Logit as a link function, was used to determine the probability of the different events. DR and BR were analysed with a mixed model with block and treatment as fixed effects. The probability of cows grazing was greater for TC than TL and lower for ruminating and DR (Table 1). There was no effect of treatment on BR (55 ± 8.8 bites/min). The changes observed on ingestive behaviour were reflected on productive performance (companion abstract).

Self-reported health problems and obesity predict sickness absence during a 12-month follow-up: a prospective cohort study in 21 608 employees from different industries

ObjectivesTo study whether self-reported health problems predict sickness absence (SA) from work in employees from different industries.MethodsThe results of a health risk appraisal (HRA) were combined with archival data of SA of 21 608 employees (59% female, 56% clerical). Exposure variables were self-reported health problems, labelled as ‘work disability (WD) risk factors’ in the HRA, presence of problems with occupational well-being and obesity. Age, socioeconomic grading and the number of SA days 12 months before the survey were treated as confounders. The outcome measure was accumulated SA days during 12-month follow-up. Data were analysed separately for males and females. A Hurdle model with negative binomial response was used to analyse zero-inflated count data of SA.ResultsThe HRA results predicted the number of accumulated SA days during the 12-month follow-up, regardless of occupational group and gender. The ratio of means of SA days varied between 2.7 and 4.0 among those with ‘WD risk factors’ and the reference category with no findings, depending on gender and occupational group. The lower limit of the 95% CI was at the lowest 2.0. In the Hurdle model, ‘WD risk factors’, SA days prior to the HRA and obesity were additive predictors for SA and/or the accumulated SA days in all occupational groups.ConclusionSelf-reported health problems and obesity predict a higher total count of SA days in an additive fashion. These findings have implications for both management and the healthcare system in the prevention of WD.

The Impact of Malaria on Liver Enzymes: A Retrospective Cohort Study (2010–2017)

BackgroundIt is unclear if malaria causes deranged liver enzymes. This has implications both in clinical practice and in research, particularly for antimalarial drug development.MethodWe performed a retrospective cohort study of returning travelers (n = 4548) who underwent a malaria test and had enzymes measured within 31 days in Calgary, Canada, from 2010 to 2017. Odds ratios of having an abnormal alkaline phosphatase (ALP), alanine aminotransferases (ALT), aspartate aminotransferases (AST), and total bilirubin (TB) were calculated using multivariable longitudinal analysis with binomial response.ResultsAfter adjusting for gender, age, and use of hepatotoxic medications, returning travelers testing positive for malaria had higher odds of having an abnormal TB (odds ratio [OR], 12.64; 95% confidence interval [CI], 6.32–25.29; P < .001) but not ALP (OR, 0.32; 95% CI, 0.09–1.10; P = .072), ALT (OR, 1.01; 95% CI, 0.54–1.89; P = .978) or AST (OR, 1.26; 95% CI, 0.22–7.37; P = .794), compared with those who tested negative. TB was most likely to be abnormal in the “early” period (day 0–day 3) but then normalized in subsequent intervals. Returning travelers with severe malaria (OR, 2.56; 95% CI, 0.99–6.62; P = .052) had borderline increased odds of having an abnormal TB, but malaria species (OR, 0.70; 95% CI, 0.24–2.05; P = .511) did not.ConclusionsIn malaria-exposed returning travelers, the TB is abnormal, especially in the early period, but no abnormalities are seen for ALT, AST, or ALP.

48 Effect of Dimethyl Sulfoxide- or Glycerol-Based Vitrification Protocols on Meiotic Spindle of In Vitro-Matured Bovine Oocytes

There is evidence suggesting that high concentrations of cryoprotectants (CPA) and very low temperatures during vitrification cause disruption of the meiotic spindle, resulting in poor post-warming meiotic resumption and other abnormalities at fertilization. This study sought to determine the damage caused by CPA and freezing upon the meiotic spindle of bovine oocytes vitrified at the metaphase II stage, and whether a subsequent incubation could promote recovery from this damage. Bovine cumulus–oocyte complexes were purchased from a commercial vendor (n = 154). Oocytes were removed from in vitro maturation media at 22 h, denuded by vortexing in hyaluronidase, and divided into 4 groups according to CPA exposure and whether they were incubated or not. The resulting groups were DMSO I (n = 36), DMSO NI (n = 41), GLY I (n = 39), GLY NI (n = 38). Two repetitions were carried out for each protocol evaluated, which included a combination of ethylene glycol (EG) with either dimethyl sulfoxide (DMSO) or glycerol (GLY). Oocytes were exposed to equilibration solution consisting of 7.5% EG and 7.5% DMSO or GLY for 9 min at room temperature (RT) and then placed into vitrification solution (VS) that contained 15% EG, 15% DMSO or GLY, and 0.5 M sucrose. While in VS, 3 to 4 denuded oocytes were loaded onto a Cryolock® (Biotech Inc., Alpharetta, GA, USA) and plunged into liquid nitrogen within 1 min. For warming, oocytes were exposed to previously warmed (37°C) dilution solution 1 (DS1) consisting of 0.5 M sucrose for 1 and 2 min at RT, for a total of 3 min in DS1, and then placed in dilution solution 2 containing 0.25 M sucrose for 3 min. Finally, oocytes were washed in base media. Base media for all solutions was PBS supplemented with 20% fetal bovine serum. After warming, half of the oocytes were fixed and the rest were submitted to a 2-h incubation period in maturation media at 37°C and 5.5% CO2, and then fixed. To examine microtubule distribution and chromosome arrangement, fixed oocytes were submitted to an immunofluorescence protocol using α-tubulin antibody (1:100) as primary antibody, Alexa Fluor 488 (1:1000) as secondary antibody, and counterstained with propidium iodide (10 mg mL−1). Oocytes were observed under a fluorescence microscope. The effects of CPA and incubation on the incidence of abnormal spindles measured with both microtubules distribution and chromosome arrangement were evaluated using logistic regression with a binomial response variable (normal/abnormal). For microtubule distribution, results showed that oocytes treated with DMSO presented significantly lower normality (31.17%) than those treated with glycerol (54.55%; P < 0.003). The most common abnormality observed in oocytes treated with DMSO was that the spindle was smaller and more faintly stained than those treated with glycerol. For chromosome arrangement, there was no significant difference between treatments (P = 0.7093). Additionally, there was no sign of improvement when submitting the oocytes to an incubation period for any of the components examined.