Evaluation of a commercially available immunoassay for assessing adequacy of passive transfer in calves

OBJECTIVE: To evaluate diagnostic utility of a commercially available immunoassay for assessing adequacy of passive transfer of immunity in neonatal calves. DESIGN: Prospective study. ANIMALS: 123 calves. PROCEDURE: Blood and serum samples were obtained from the calves prior to 2 weeks of age. The immunoassay was performed, along with refractometry and an 18% sodium sulfite turbidity test. Serum IgG concentration was determined with a radial immunodiffusion assay. Sensitivity and specificity of the immunoassay, refractometry, and the sodium sulfite test were calculated by comparing results with results of the radial immunodiffusion assay. RESULTS: Sensitivity and specificity of the blood IgG immunoassay were 0.93 and 0.88, respectively, compared with 1.00 and 0.53 for the sodium sulfite test. For refractometry, sensitivity and specificity were 0.71 and 0.83, respectively, when a serum total solids concentration of 5.2 g/dl was used as the cutoff between positive and negative test results. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that the immunoassay performs well in detecting calves with inadequate passive transfer of immunity.     

Neurotoxicity of a fragment of the amyloid precursor associated with Alzheimer's disease

Amyloid deposition in senile plaques and the cerebral vasculature is a marker of Alzheimer's disease. Whether amyloid itself contributes to the neurodegenerative process or is simply a by-product of that process is unknown. Pheochromocytoma (PC12) and fibroblast (NIH 3T3) cell lines were transfected with portions of the gene for the human amyloid precursor protein. Stable PC12 cell transfectants expressing a specific amyloid-containing fragment of the precursor protein gradually degenerated when induced to differentiate into neuronal cells with nerve growth factor. Conditioned medium from these cells was toxic to neurons in primary hippocampal cultures, and the toxic agent could be removed by immunoabsorption with an antibody directed against the amyloid polypeptide. Thus, a peptide derived from the amyloid precursor may be neurotoxic.     

Integration of sapflow velocity in elliptical stems

The estimation of water flux through the stem of a plant by point estimates based on the heat pulse technique requires integration of the velocity profile. The polynomial integration method and the weighted average technique both assume radial symmetry about the bole. A method is introduced that solves the equations for the ellipse in the weighted average technique, and includes an optimizing algorithm for the placement of sensors. The sensitivity of sapflow estimates through stems to increasing eccentricity is examined by means of analytical solutions and simulation. The error in sap flux measurement resulting from the radial approximation of the sapwood conducting area is expressed analytically and shown to be small over the range of eccentricities (e < 0.8) expected in nature. Simulations where radial symmetry is assumed for elliptical stems show substantial error in mean velocity (and thus flux) with modest eccentricities (e > 0.4).     

Effects of supplemental lactoferrin on serum lactoferrin and IgG concentrations and neutrophil oxidative metabolism in Holstein calves

Lactoferrin (LF) is an iron-binding protein present in both colostrum and secondary granules of polymorphonuclear neutrophils (PMNs). We hypothesized that supplemental LF enhances neutrophil function in neonatal calves. Newborn calves were assigned to receive colostrum (C), colostrum + LF (CLF, 1 g/kg), or milk replacer + LF (MRLF, 1 g/kg). Serum (LF and IgG) and whole blood (neutrophil isolation) samples were obtained prior to treatment (day 0) and at 24 hours and 9 days of age. Serum IgG concentrations (mean +/- SD) in C, CLF, and MRLF calves at 24 hours were 1,911 +/- 994 mg/dL, 2,181 +/- 625 mg/dL, and 0 mg/ dL, respectively. Serum LF concentrations in C, CLF, and MRLF calves on day 0 were 324 +/- 334 ng/mL (range 0-863 ng/mL), 135 +/- 158 ng/mL (range 0-429 ng/mL), and 318 +/- 337 ng/mL (range 0-964 ng/mL), respectively. LF concentrations in C, CLF, and MRLF calves at 24 hours were significantly higher (P < .05), at 1,564 +/- 1,114 ng/mL (range 335-3,628 ng/mL, 2,237 +/- 936 ng/mL (range 31-3,287 ng/mL), and 3,189 +/- 926 ng/mL (range 1,736-4,120 ng/mL), respectively. Cytochrome c reduction in opsonized zymosan-treated or phorbol ester-treated cells was not significantly affected by supplemental LF provided at birth. Oral LF is absorbed in calves but does not alter PMN superoxide production and does not alter IgG absorption.     

Diurnal and seasonal variations in CH4 flux from termite mounds in tropical savannas of the Northern Territory, Australia

Termites are estimated to contribute between <5 and 19% of the global methane (CH₄) emissions. These estimates have large uncertainties because of the limited number of field-based studies and species studied, as well as issues of diurnal and seasonal variations. We measured CH₄ fluxes from four common mound-building termite species (Microcerotermes nervosus, M. serratus, Tumulitermes pastinator and Amitermes darwini) diurnally and seasonally in tropical savannas in the Northern Territory, Australia. Our results showed that there were significant diel and seasonal variations of CH₄ emissions from termite mounds and we observed large species specific differences. On a diurnal basis, CH₄ fluxes were least at the coolest time of the day (∼07.00 h) and greatest at the warmest (∼15.00 h) for all species for both wet and dry seasons. We observed a strong and significant positive correlation between CH₄ flux and mound temperature for all species. A mound excavation experiment demonstrated that the positive temperature effect on CH₄ emissions was not related to termite movement in and out of a mound but probably a direct effect of temperature on methanogenesis in the termite gut. Fluxes in the wet season were 5-26-fold greater than those in the dry season. A multiple stepwise regression model including mound temperature and mound water content described 70-99% of the seasonal variations in CH₄ fluxes for different species. CH₄ fluxes from M. nervosus, which was the most abundant mound-building termite species at our sites, had significantly lower fluxes than the other three species measured. Our data demonstrate that CH₄ flux estimates could result in large under- or over-estimation of CH₄ emissions from termites if the diurnal, seasonal and species specific variations are not accounted for, especially when flux data are extrapolated to landscape scales.     

Effect of delayed colostrum collection on colostral IgG concentration in dairy cows

OBJECTIVE: To determine the effect of timing of first-milking colostrum collection on colostral IgG concentration. DESIGN: Prospective study. ANIMALS: 13 healthy Holstein cows. PROCEDURES: All calvings were observed. After parturition, calves were not allowed to suckle and were separated from the dam. Colostrum was collected from a single randomly selected quarter at 2, 6, 10, and 14 hours after parturition until all 4 quarters were sampled. Colostral IgG concentration was determined via radial immunodiffusion. RESULTS: Mean colostral IgG concentration was 113, 94, 82, and 76 g/L at 2, 6, 10, and 14 hours after calving, respectively. Colostrum collected 6, 10, and 14 hours after calving had significantly lower IgG concentrations than did colostrum collected 2 hours after calving. Mean colostral IgG concentration at 14 hours after calving was significantly lower than that at 6 hours after calving. Cows in their third or greater lactation had mean colostral IgG concentrations 2 hours after calving (132 g/L) that were greater than the first and second lactation cows (mean, 95 and 100 g/L, respectively). CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that early or immediate colostrum collection from dairy cows will maximize colostral IgG concentration. Adjustment of routine dairy farm management procedures may be required to maximize colostrum quality and minimize prevalence of failure of passive transfer in dairy calves.     

In vitro effects of lactoferrin on lipopolysaccharide-induced proliferation, gene expression, and prostanoid production by bovine peripheral blood mononuclear cells

Objective-To evaluate the effect of lactoferrin on lipopolysaccharide (LPS)-induced proliferation of bovine peripheral blood mononuclear cells (PBMCs), gene expression of inflammatory mediators, and production of prostanoids in vitro. Sample Population-PBMCs isolated from 15 Holstein bull calves. Procedures-Mixed populations of PBMCs were isolated by differential centrifugation. Proliferation assays were conducted in 96-well plates designed to allow addition of lactoferrin (200 ng/mL) with and without LPS (1 mug/mL) in a checkerboard design. Incorporation of (3)H-thymidine was used to determine proliferation of PBMCs. Prostaglandin E(2) production was determined in culture-conditioned medium by use of enzyme immunoassay. Effects of lactoferrin on LPS-induced gene expression of cyclooxygenase (COX)-2 and matrix metalloproteinase (MMP)-9 were monitored by use of PCR assays. Results-Lactoferrin supplementation significantly reduced LPS-induced incorporation of (3)H-thymidine and production of prostaglandin E(2) by PBMCs. Lactoferrin reduced LPS-induced expression of COX-2 and MMP-9 mRNA. Conclusions and Clinical Relevance-Lactoferrin reduced LPS-induced cellular proliferation, inflammatory mediator gene expression, and prostaglandin E(2) production by bovine PBMCs in vitro. These effects may be beneficial in reducing the impact of endotoxemia in neonates.     

Using Multivariate Analysis to Predict the Behaviour of Soils Under Effluent Irrigation

Onsite wastewater treatment systems aim to assimilate domestic effluent into the environment. Unfortunately failure of such systems is common and inadequate effluent treatment can have serious environmental implications. The capacity of a particular soil to treat wastewater will change over time. The physical properties influence the rate of effluent movement through the soil and its chemical properties dictate the ability to renovate effluent. A research project was undertaken to determine the role that physical and chemical soil properties play in predicting the long-term behaviour of soil under effluent irrigation and to determine if they have a potential function as early indicators of adverse effects of effluent irrigation on treatment sustainability. Principal Component Analysis (PCA) and Cluster Analysis grouped the soils independently of their soil classifications and allowed us to distinguish the most suitable soils for sustainable long term effluent irrigation and determine the most influential soil parameters to characterise them. Multivariate analysis allowed a clear distinction between soils based on the cation exchange capacities. This in turn correlated well with the soil mineralogy. Mixed mineralogy soils in particular sodium or magnesium dominant soils are the most susceptible to dispersion under effluent irrigation. The soil Exchangeable Sodium Percentage (ESP) was identified as a crucial parameter and was highly correlated with percentage clay, electrical conductivity, exchangeable sodium, exchangeable magnesium and low Ca:Mg ratios (less than 0.5).