Placental weight is a valuable indicator of its function, predicting both pregnancy outcome and lifelong health. Population-based centile charts of weight-for-gestational-age and parity are useful for identifying extremes of placental weight but fail to consider maternal size. To address this deficit, a multiple regression model was fitted to derive coefficients for predicting normal placental weight using records from healthy pregnancies of nulliparous/multiparous women of differing height and weight (n = 107,170 deliveries, 37–43 weeks gestation). The difference between actual and predicted placental weight generated a z-score/individual centile for the entire cohort including women with pregnancy complications (n = 121,591). The association between maternal BMI and placental weight extremes defined by the new customised versus population-based standard was investigated by logistic regression, as was the association between low placental weight and pregnancy complications. Underweight women had a greater risk of low placental weight [<10thcentile, OR 1.84 (95% CI 1.66, 2.05)] and obese women had a greater risk of high placental weight [>90th centile, OR 1.98 (95% CI 1.88, 2.10)] using a population standard. After customisation, the risk of high placental weight in obese/morbidly obese women was attenuated [OR 1.17 (95% CI 1.09, 1.25)]/no longer significant, while their risk of low placental weight was 59%–129% higher (P < 0.001). The customised placental weight standard was more closely associated with stillbirth, hypertensive disease, placental abruption and neonatal death than the population standard. Our customised placental weight standard reveals higher risk of relative placental growth restriction leading to lower than expected birthweights in obese women, and a stronger association between low placental weight and pregnancy complications generally. Further, it provides an alternative tool for defining placental weight extremes with implications for the placental programming of chronic disease.

Background: As with other specialties, Royal College of Physicians and Surgeons of Canada (RCPSC) trainees in Neurosurgery have anecdotally had challenges securing full-time employment. This study presents the employment status, research pursuits, and fellowship choices of neurosurgery trainees in Canadian programs. Methods: RCPSC neurosurgery trainees (n = 143) who began their residency training between 1998 and 2008 were included in this study. Associations between year of residency completion, research pursuits, and fellowship choice with career outcomes were determined by Fisher’s exact test (p < 0.05, statistical significance). Results: In 2015, 60% and 26% of neurosurgery trainees had permanent positions in Canada and the USA, respectively. Underemployment, defined as locum and clinical associate positions, pursuit of multiple unrelated fellowships, unemployment, and career change to non-surgical career, was 12% in 2015. The proportion of neurosurgery trainees who had been underemployed at some point within 5 years since residency completion was 20%. Pursuit of in-folded research (MSc, PhD, or non-degree research greater than 1 year) was significantly associated with obtaining full employment (94% vs. 73%, p = 0.011). However, fellowship training was not significantly associated with obtaining full employment (78% vs. 75%, p = 1.000). Conclusions: Underemployment in neurosurgery has become a significant issue in Canada for various reasons. Pursuit of in-folded research, but not fellowship training, was associated with obtaining full employment.

Proactive integrated weed management (IWM) is critically needed in no-till production to reduce the intensity of selection pressure for herbicide-resistant weeds. Reducing the density of emerged weed populations and the number of larger individuals within the population at the time of herbicide application are two practical management objectives when integrating cover crops as a complementary tactic in herbicide-based production systems. We examined the following demographic questions related to the effects of alternative cover-cropping tactics following small grain harvest on preplant, burndown management of horseweed (Erigeron canadensis L.) in no-till commodity-grain production: (1) Do cover crops differentially affect E. canadensis density and size inequality at the time of herbicide exposure? (2) Which cover crop response traits are drivers of E. canadensis suppression at time of herbicide exposure? Interannual variation in growing conditions (study year) and intra-annual variation in soil fertility (low vs. high nitrogen) were the primary drivers of cover crop response traits and significantly affected E. canadensis density at the time of herbicide exposure. In comparison to the fallow control, cover crop treatments reduced E. canadensis density 52% to 86% at the time of a preplant, burndown application. Cereal rye (Secale cereale L.) alone or in combination with forage radish (Raphanus sativus L.) provided the most consistent E. canadensis suppression. Fall and spring cover crop biomass production was negatively correlated with E. canadensis density at the preplant burndown application timing. Our results also show that winter-hardy cover crops reduce the size inequality of E. canadensis populations at the time of herbicide exposure by reducing the number of large individuals within the population. Finally, we advocate for advancement in our understanding of complementarity between cover crop– and herbicide-based management tactics in no-till systems to facilitate development of proactive, herbicide-resistant management strategies.

The kinetics of silica polymerization was measured in silicic acid solutions containing a suite of 0.1 M amino acids, 0.1 M citric acid, 0.7 M NaCl, and 0.10 M NaCl (Control). Fitting a modified classical rate model to measurements of induction time (τ) at 20 °C for a series of supersaturated solutions, we estimate the thermodynamic barrier (ΔGc), interfacial free energy (γ), and kinetic barrier (Δagk) for silica nucleation. For 0.10 M NaCl solutions, γControl = 54.9 ± 1.6 mJ/m2 and ΔagkControl = 2.29 × 10−19 J/mol. These values are consistent with previous reports for amorphous and fused silica materials. To facilitate comparisons with the treatments, ΔagkControl is converted to a molar basis and used as a reference datum, such that ΔagkControl = 0.0 J/mol. The effects of salt and organic acids on nucleation rate have thermodynamic and kinetic origins, respectively. Faster nucleation rates measured in 0.7 M NaCl solutions arise from a lower interfacial free energy, such that γ0.7 M NaCl = 51.4 ± 1.7 mJ/m2. Organic acids increase rate through biomolecule-specific reductions in Δagk. Catalytic effects are greatest for lysine (Δagklysine = −1685 ± 315) and citric acid (Δagkcitric = −1690 ± 96 J/mol). Reductions in the kinetic barrier correlate with net positive charge of the amino acids and dissociation of the amine $\left( {{K_{\alpha {\rm{ ‐ N}}{{\rm{H}}_3}^ {\bf{+}} }}} \right)$ group and thus the abundance of the conjugate base. Citric acid, lacking amine groups, promotes the greatest rate enhancement, thus demonstrating the role(s) of additional kinetic factors in promoting nucleation rate. Catalytic activity correlates with multiple physical and chemical properties of the organic acids.

Objectives: The high rate of cannabis (CAN) use in emerging adults is concerning given prior research suggesting neurocognitive deficits associated with CAN use in youth. Regular CAN use downregulates endocannabinoid activity, while aerobic exercise upregulates cannabinoid receptor 1 activity and releases endocannabinoids. Here we investigate the influence of regular CAN use on neuropsychological performance, and whether aerobic fitness moderates these effects. Methods: Seventy-nine young adults (37 CAN users) aged 16–26 participated. Groups were balanced for aerobic fitness level. Exclusion criteria included: left-handedness, past-year independent Axis-I disorders, major medical/neurologic disorders, prenatal issues, or prenatal alcohol/illicit drug exposure. After 3 weeks of abstinence, participants completed a neuropsychological battery and a maximal oxygen consumption test (VO2 max). Multiple regressions tested whether past-year CAN use, VO2 max, and CAN*VO2 max interaction predicted neuropsychological performance, controlling for past-year alcohol use, cotinine, gender, and depression symptoms. Results: Increased CAN use was associated with decreased performance on working memory and psychomotor tasks. High aerobic fitness level was related to better performance on visual memory, verbal fluency, and sequencing ability. CAN*VO2 max predicted performance of psychomotor speed, visual memory, and sequencing ability. Conclusions: Following monitored abstinence, increased CAN use was associated with poorer performance in working memory and psychomotor speed. Higher aerobic fitness level moderated the impact of CAN on visual memory, executive function and psychomotor speed, as more aerobically fit CAN users demonstrated better performance relative to low-fit users. Therefore, aerobic fitness may present an affordable and efficacious method to improve cognitive functioning in CAN users. (JINS, 2019, 25, 134–145)

This study assessed bioavailability and utilisation of vitamin D3 in two feeding trials using young, growing Sprague–Dawley male rats. Trial one fed animals standard AIN-93G diet (casein protein) containing no vitamin D3 and goat or cow skimmed milk supplemented with vitamin D3. Trial two fed animals modified dairy-free AIN-93G diet (egg albumin) containing no vitamin D3 and goat or cow skimmed or full-fat milk supplemented with vitamin D3. Control groups received AIN-93G diets with or without vitamin D, and water. At 8 weeks of age, blood samples were collected for vitamin and mineral analysis, and femurs and spines were collected for assessment of bone mineralisation and strength. In both trials, analyses showed differences in bioavailability of vitamin D3, with ratios of serum 25-hydroxyvitamin D3 to vitamin D3 intake more than 2-fold higher in groups drinking supplemented milk compared with groups fed supplemented solid food. Bone mineralisation was higher in groups drinking supplemented milk compared with groups fed supplemented solid food, for both trials (P<0·05). There was no difference in the parameters tested between skimmed milk and full-fat milk or between cow milk and goat milk. Comparison of the two trials suggested that dietary protein source promoted bone mineralisation in a growing rat model: modified AIN-93G with egg albumin produced lower bone mineralisation compared with standard AIN-93G with casein. Overall, this study showed that effects of vitamin D3 deficiency in solid diets were reversed by offering milk supplemented with vitamin D3, and suggests that using milk as a vehicle to deliver vitamin D is advantageous.

Infection by parasites is a major cause of production losses and mortality in young calves. The problem is most prevalent during the first grazing season (Armour, 1989). Eosinophils are important cellular mediators in immunity to gastrointestinal parasites (Baker et al, 1993), but during an extreme hypersensitivity immune response, degranulating eosinophils may lead to tissue pathology which may favour parasite survival (Miller, 1996). Dietary polyunsaturated fatty acids (PUFA) influence the fatty acid composition of immune tissues and cells (Jaffrey, 1998). n-6 and n-3 fatty acids are known to influence various components of immune response via eicosanoid dependent or independent mechanisms which influence the relative proportions of Th1 and Th2 cytokines, including IL-5 an important regulator of eosinophils maturation and recruitment. This study was carried out to establish the extent to which dietary n-6 or n-3 PUFA source affects the numbers of eosinophils in the gut of calves.

Dietary fatty acids have been shown to affect the activity of the immune system in a variety of species through eicosanoid dependent or independent mechanisms (Miles 1998, Calder 2001). MLN and spleen are lymphoid tissues which play a key role in the immune function. Changing the fatty acid composition of these tissues could change the profile of eicosanoid produced by immune cells in these tissues and this could alter the immune response. This study was carried out to establish the extent to which different oil supplements could change the fatty acid composition of MLN and spleen in milk fed calves.

In pre-ruminant calves the oesophageal groove reflex allows milk to bypass the developing rumen and is a mechanism by which dietary fatty acids can be delivered directly to the small intestine. This experiment was a pilot study carried out to establish the extent and time course of the changes in plasma fatty acid composition in calves fed milk supplemented with oils of differing fatty acid composition and allowed minimal access to roughage (straw bedding). The work was carried out to provide baseline data for a longer study with calves in which rumen development will be encouraged by feeding solid food but the oesophageal groove reflex will be maintained through long term milk feeding and used as a means of delivering polyunsaturated fatty acids (PUFA) directly to the small intestine.

Dietary fatty acids have been shown to affect the activity of the immune system in a variety of species (Calder, 1998) although the exact mechanism by which they influence the nature of the immune response is unclear. The effect of dietary fatty acids on the fatty acid composition of intestinal mucosa is important since this tissue has a rapid turn over and is a major site of antigenic exposure and immune defence. The speed with which changes in dietary fatty acid intake are reflected in the fatty acid composition of cells and tissue of the body varies. In ruminants the development of a functional rumen greatly influences the nature of the fatty acids available for absorption from the small intestine, however, in pre-ruminant animals, milk may be used as a medium to supplement the diet with specific dietary fatty acids. This work was carried out to establish the extent to which different oil supplements could change the fatty acid composition of intestinal mucosa in milk fed pre-ruminant calves.

The balance between pro and anti-inflammatory elements of the immune system can be influenced by provision of specific dietary polyunsaturated fatty acids (PUFA) (Calder, 1998). The gut associated lymphoid tissue (GALT) is the largest immune organ and an important regulator of tolerance and sensitivity to dietary and environmental antigens in the gut (Harbige and Fisher, 2001). Changing the fatty acid composition of the gut mucosa could influence the immune function of the GALT. This study was carried out to establish the extent to which dietary n-3 or n-6 PUFA-rich oil supplements could change the fatty acid composition of gut mucosa of the neonatal calf.

The efficiency and rate of microbial protein synthesis in the rumen depend on several factors, of which the chemical and physical properties of the plant fibre are among the most important. Estimation of microbial yield and fermentation rate can be obtained from in vitro experiments, which combine gas production and substrate degradability measurements and/or use microbial markers. The aim of this study was to investigate the effect of different fibre sources on microbial protein synthesis in a batch culture system in vitro.