The measurement of the degree of saturation of soils with bases

1. To determine the degree of saturation of a soil, data must be secured to show the amount of replaceable bases, replaceable hydrogen and base exchange capacity. 2. Experiments have been conducted to determine the accuracy of various methods for these determinations. 3. A study was first made of the electrodialysis method for replaceable bases, using both the Mattson and the Bradfield cells. 4. When 100 grams of soil were electlodialyzed in the Mattson cell for 45 hours, the results seemed satisfactory when compared with the data secured with other methods. 5. When a smaller amount of soil (10 grams) was electrodialyzed in either the Mattson or the Bradfield cell for a shorter time, the end point was not definite and the results could not be considered accurate. Furthermore, there was a continued extraction of basic materials from the soil after more bases had been removed by electrodialysis than were known to be present in a replaceable form in the soil. Hence, it appears that the error in this method may be greater than that caused by solubility effects in the leaching methods. 6. The Hissink (T - S) method for determining the replaceable hydrogen in the soil was compared with the method developed by Parker. 7. In a number of Iowa soils differing widely in characteristics and in soils which had been treated with various amounts of limestone of different degrees of fineness, the Hissink method gave practically the same amounts of replaceable hydrogen. 8. There seemed to be no correlation between the replaceable hydrogen in the soil, when measured by the Hissink method, and the hydrogen ion concentration. With the Webster silty clay loam which had a pH of 7.48, the Hissink method showed more replaceable hydrogen than was found in the Tama silt loam which had a pH of 4.79. 9. The amount of replaceable hydrogen found by the Hissink method was greater in all the soils tested than the total base exchange capacity of the soils. According to Kelley. when this method is used, not only does the barium hydroxide added to the soil react with the exchangeable hydrogen but other side reactions occur. The results with the method are certainly rather unsatisfactory. 10. According to the accepted theories of base exchange, the Parker method for determining replaceable hydrogen is sound in principle and the data secured in this work show that it will give accurate and reliable results. 11. The Parker method for determining the base exchange capacity of soils was also found to give excellent results. The principle of this method has been well established and the method has been used, with certain modifications in technic, by other investigators. 12. After the replaceable hydrogen and base exchange capacity are determined by the Parker method, the amount of replaceable bases and the degree of saturation with bases may be calculated. 13. This method has been tested on a number of Iowa soils and on soils treated with various amounts of lime of different degrees of fineness. In all cases satisfactory results have been secured. 14. In general it is evident that of all the methods tested. that proposed by Parker seems to give the best picture of the actual condition of the base exchange complex in soils. 15. Certain modifications in the technic of this method have been suggested for future work

Relationship between urinary energy and urinary nitrogen or carbon excretion in lactating Jersey cows

Measurement of urinary energy (UE) excretion is essential to determine metabolizable energy (ME) supply. Our objectives were to evaluate the accuracy of using urinary N (UN) or C (UC) to estimate UE and ultimately improve the accuracy of estimating ME. Individual animal data (n = 433) were used from 11 studies with Jersey cows at the University of Nebraska–Lincoln, where samples were analyzed after drying (n = 299) or on an as-is basis (n = 134). Dried samples resulted in greater estimated error variance compared with as-is samples, and thus only as-is samples were used for final models. The as-is data set included a range (min to max) in dry matter intake (11.6–24.6 kg/d), N intake (282–642 g/d), UE excretion (1,390–3,160 kcal/d), UN excretion (85–220 g/d or 20.6–59.5% of N intake), and UC excretion (130–273 g/d). As indicated by a bias in residuals between observed and predicted ME as dietary crude protein (CP; range of 14.9–19.1%) increased, the National Research Council dairy model did not accurately predict ME of diets, as dietary CP varied. The relationship between UE (kcal/d) and UN (g/d) excretion was linear and had an intercept of 880 ± 140 kcal. Because an intercept of 880 is biologically unlikely, the intercept was forced through 0, resulting in linear and quadratic relationships. The regressions of UE (kcal/d) on UN (g/d) excretion were UE = 14.6 ± 0.32 × UN, and UE = 20.9 ± 1.0 × UN − 0.0357 ± 0.0056 × UN2. In the quadratic regression, UE increased, but at a diminishing rate as UN excretion increased. As UC increased, UE linearly and quadratically increased. However, error variance was greater for regression with UC compared with UN as explanatory variables (8.42 vs. 7.42% of mean UE). The use of the quadratic regression between UN and UE excretion to predict ME resulted in a slope bias in ME predictions as dietary CP increased. The linear regression between UE and UN excretion removed slope bias between predicted ME and CP, and thus may be more appropriate for predicting UE across a wider range of dietary CP. Using equations to predict UE from UN should improve our ability to predict diet ME in Jersey cows compared with calculating ME directly from digestible energy

Inhibition of Rotavirus Infectivity by a Neoglycolipid Receptor Mimetic

Group A rotaviruses are a major cause of diarrhea in the young of many mammalian species. In rotavirus infected piglets mortality can be as high as 60%. Previous research in this laboratory has identified a porcine intestinal GM3 ganglioside receptor that is required for sialic acid-dependent rotavirus recognition of host cells. In addition, we previously demonstrated exogenously added GM3 can competitively inhibit porcine rotavirus binding and infectivity of host cells in vitro. Sialyllactose, the carbohydrate moiety of GM3, is approximately 3 orders of magnitude less effective than GM3 at inhibiting rotavirus binding to cells. Furthermore, production of therapeutic quantities of GM3 ganglioside for use as an oral carbomimetic in swine is cost prohibitive. In an effort to circumvent these problems, a sialyllactose-containing neoglycolipid was synthesized and evaluated for its ability to inhibit rotavirus binding and infectivity of host cells. Sialyllactose was coupled to dipalmitoylphosphatidylethanolamine (PE) by reductive amination and the product (SLPE) purified by HPLC. Characterization of the product showed a single primulin (lipid) and resorcinol (sialic acid) positive band by thin layer chromatography and quantification of phosphate and sialic acid yielded a 1:1 molar ratio. Mass spectroscopy confirmed a molecular weight coinciding with SLPE. Concentration-dependent binding of rotavirus to SLPE was demonstrated using a thin-layer overlay assay. Using concentrations comparable to GM3, SLPE was also shown to inhibit rotavirus binding to host cells by 80%. Furthermore, SLPE was shown to decrease rotavirus infection of host cells by over 90%. Finally, preliminary results of in vivo animal challenge studies using newborn piglets in their natural environment, demonstrated SLPE afforded complete protection from rotavirus disease. The efficacy of SLPE in inhibiting rotavirus binding and infection in vitro and in vivo, coupled with its relatively low-cost, large-scale production capabilities make SLPE a promising candidate for further exploration as a possible prophylactic or therapeutic nutriceutical for combating rotavirus disease in animals. Most importantly, the results presented here provide proof of concept that the nutriceutical approach of providing natural or synthetic dietary receptor mimetics for protection against gastrointestinal virus infectious disease in all species is plausible

The effect of feed withdrawal on the shedding of Salmonella typhimurium by swine

This project was designed to determine if feed withdrawal in conjunction with transportation-related stress caused increased shedding of Salmonella by carrier pigs. In this experiment, 48 pigs were challenged orally with S. typhimurium after weaning and allowed to grow under typical production practices. Antibiotics were not included in feeds. At monthly intervals, fecal and serum samples were collected from each pig. All pigs shed the challenge organism at least once during the experiment. By the sixth month, most pigs were negative for the challenge organism when cultured from feces. When pigs reached market weight (-240 pounds), they were split into 4 groups and subjected to one of the following feed withdrawal protocols: group I had no feed withdrawal, groups 2-4 had feed withdrawn at 6, 12 or 24 hours, respectively. Pigs in each group were transported -225 kilometers (4 hours), returned to the production facility and necropsied. Contents at the ileal-cecal junction were collected and cultured for the test organism. There was a direct correlation between the time of feed withdrawal and the number of pigs with S. typhimurium in intestinal contents. Pigs that had no feed withdrawal had the fewest number of positive pigs, whereas pigs that were off feed for 24 hours had the highest number of positive pigs. Serum samples were assessed using a mixed ELISA to detect antibodies against Salmonella. All pigs had detectable antibodies. Over the various bleedings, most pigs exhibited increases in anti-Salmonella antibodies over time. Some had modest drop-offs at the later times. In about I 0% of pigs, there was no increase or decrease in anti-Salmonella antibodies. In these non-responding pigs, the specific titers were lower than responding pigs, and above background levels. The results from this experiment complement our previous work and demonstrated that feed withdrawal when in conjunction with shipping contributes to shedding of Salmonella by pigs. Most pigs were not shedding the challenge organism just prior to slaughter, yet most (\u3e80%) had persistent infections. This indicates that the detection of infected, asymptomatic carriers using conventional culture methods is difficult and could complicate plans to develop programs to certify Salmonella-free pigs

Evaluation of the National Research Council (2001) dairy model and derivation of new prediction equations. 1. Digestibility of fiber, fat, protein, and nonfiber carbohydrate

Evaluation of ration balancing systems such as the National Research Council (NRC) Nutrient Requirementsseries is important for improving predictions of animal nutrient requirements and advancing feeding strategies. This work used a literature data set (n = 550) to evaluate predictions of total-tract digested neutral detergent fiber (NDF), fatty acid (FA), crude protein (CP), and nonfiber carbohydrate (NFC) estimated by the NRC (2001) dairy model. Mean biases suggested that the NRC (2001) lactating cow model overestimated true FA and CP digestibility by 26 and 7%, respectively, and under-predicted NDF digestibility by 16%. All NRC (2001) estimates had notable mean and slope biases and large root mean squared prediction error (RMSPE), and concordance (CCC) ranged from poor to good. Predicting NDF digestibility with independent equations for legumes, corn silage, other forages, and nonforage feeds improved CCC (0.85 vs. 0.76) compared with the re-derived NRC (2001) equation form (NRC equation with parameter estimates re-derived against this data set). Separate FA digestion coefficients were derived for different fat supplements (animal fats, oils, and other fat types) and for the basal diet. This equation returned improved (from 0.76 to 0.94) CCC compared with the re-derived NRC (2001) equation form. Unique CP digestibility equations were derived for forages, animal protein feeds, plant protein feeds, and other feeds, which improved CCC compared with the re-derived NRC (2001) equation form (0.74 to 0.85). New NFC digestibility coefficients were derived for grain-specific starch digestibilities, with residual organic matter assumed to be 98% digestible. A Monte Carlo cross-validation was performed to evaluate repeatability of model fit. In this procedure, data were randomly subsetted 500 times into derivation (60%) and evaluation (40%) data sets, and equations were derived using the derivation data and then evaluated against the independent evaluation data. Models derived with random study effects demonstrated poor repeatability of fit in independent evaluation. Similar equations derived without random study effects showed improved fit against independent data and little evidence of biased parameter estimates associated with failure to include study effects. The equations derived in this analysis provide interesting insight into how NDF, starch, FA, and CP digestibilities are affected by intake, feed type, and diet composition

Brain-behaviour modes of covariation in healthy and clinically depressed young people.

Understanding how variations in dimensions of psychometrics, IQ and demographics relate to changes in brain connectivity during the critical developmental period of adolescence and early adulthood is a major challenge. This has particular relevance for mental health disorders where a failure to understand these links might hinder the development of better diagnostic approaches and therapeutics. Here, we investigated this question in 306 adolescents and young adults (14-24 y, 25 clinically depressed) using a multivariate statistical framework, based on canonical correlation analysis (CCA). By linking individual functional brain connectivity profiles to self-report questionnaires, IQ and demographic data we identified two distinct modes of covariation. The first mode mapped onto an externalization/internalization axis and showed a strong association with sex. The second mode mapped onto a well-being/distress axis independent of sex. Interestingly, both modes showed an association with age. Crucially, the changes in functional brain connectivity associated with changes in these phenotypes showed marked developmental effects. The findings point to a role for the default mode, frontoparietal and limbic networks in psychopathology and depression.Wellcome Trus

Effects of metal-on-metal wear on the host immune system and infection in hip arthroplasty

Methods We reviewed the available literature on the influence of degradation products of MOM bearings in total hip arthroplasties on infection risk. Results Wear products were found to influence the risk of infection by hampering the immune system, by inhibiting or accelerating bacterial growth, and by a possible antibiotic resistance and heavy metal co-selection mechanism. Interpretation Whether or not the combined effects of MOM wear products make MOM bearings less or more prone to infection requires investigation in the near future

Conservative and disruptive modes of adolescent change in human brain functional connectivity

Adolescent changes in human brain function are not entirely understood. Here, we used multiecho functional MRI (fMRI) to measure developmental change in functional connectivity (FC) of resting-state oscillations between pairs of 330 cortical regions and 16 subcortical regions in 298 healthy adolescents scanned 520 times. Participants were aged 14 to 26 y and were scanned on 1 to 3 occasions at least 6 mo apart. We found 2 distinct modes of age-related change in FC: “conservative” and “disruptive.” Conservative development was characteristic of primary cortex, which was strongly connected at 14 y and became even more connected in the period from 14 to 26 y. Disruptive development was characteristic of association cortex and subcortical regions, where connectivity was remodeled: connections that were weak at 14 y became stronger during adolescence, and connections that were strong at 14 y became weaker. These modes of development were quantified using the maturational index (MI), estimated as Spearman’s correlation between edgewise baseline FC (at 14 y, FC14) and adolescent change in FC ( ), at each region. Disruptive systems (with negative MI) were activated by social cognition and autobiographical memory tasks in prior fMRI data and significantly colocated with prior maps of aerobic glycolysis (AG), AG-related gene expression, postnatal cortical surface expansion, and adolescent shrinkage of cortical thickness. The presence of these 2 modes of development was robust to numerous sensitivity analyses. We conclude that human brain organization is disrupted during adolescence by remodeling of FC between association cortical and subcortical areas