Research aimed at optimizing diagnostic laboratory procedures is central to the development of effective bovine viral diarrhoea virus (BVDV) control programmes. BVDV is a single-stranded RNA virus that crosses the placenta to infect foetuses resulting in reproductive losses due to foetal death or persistently infected (PI) calves that usually die early in life. Persistently infected animals are widely accepted to be the primary reservoir of BVDV and the largest source of BVDV infection. Persistently infected animals that survive calfhood are at risk of developing mucosal disease in later life which is a severe and usually fatal condition. In addition, persistently infected calves that become replacement heifers in the herd may experience significant morphological changes that occur in the ovaries which can result in impaired reproductive performance. This poses important challenges to overall animal/herd health and causes losses to the cattle industry. Long-term storage of bovine ear notch samples from calves persistently infected (PI) with BVDV may affect the ability of diagnostic assays to efficiently detect the virus. This study assessed the effects of 1) long-term storage of formalin-fixed samples at room temperature to detect BVD viral antigen with the aid of immunohistochemistry (IHC), 2a) long-term storage of fresh ear notch samples kept at -20°C, and 2b) long term storage of phosphate-buffered saline (PBS) ear notch supernatant kept at -20°C on the ability of an antigen-capture ELISA (AC-ELISA) to detect viral antigen. Previous studies have verified 100% sensitivity for both AC-ELISA on ear notch supernatant and immunohistochemical testing of ear notches to detect BVDV provided that samples are properly collected and stored. In this study, ear notch samples from seven animals were subjected to prompt formalin fixation and fresh samples to prolonged storage at -20°C. Frozen ear notches and ear notch supernatant yielded positive results on AC-ELISA for the duration of the study, i.e. 6 months, and OD values remained significantly within range. There was no significant difference between storing fresh ear notch samples and PBS ear-notch supernatant at -20°C. However, positive IHC staining on formalin-fixed ear notches started to fade away between day 17 and day 29 when stored at room temperature. We conclude that fresh ear notches could safely be stored at -20°C for a period of 6 months for detecting BVD viral antigen at a later stage. Copyright / Dissertation (MSc)--University of Pretoria, 2009. / Veterinary Tropical Diseases / unrestricted

Background: Caries continue to be a risk to children’s health and a stagnation of improvement has been seen the last years with 5% of Swedish three year olds being caries active. Earlier studies show a connection between presence of Streptococcus mutans  in saliva and caries prevalence, and that Streptococcus mutans can be transmitted from mother to child.   Aim: To study prevalence of Streptococcus mutans in three year old children and their mothers. To gain a deeper understanding of maternal transmission of Streptococcus mutans and other factors elevating the risk of caries in children.  Methods: Saliva samples and questionnaires were collected from 150 Swedish mothers and their three year old children, and a clinical dental examination was performed. PCR-technique were used to look for Streptococcus mutans in the saliva samples. Results from the questionnaires and saliva experiments were analyzed using SPSS.  Results: The total caries prevalence including initial and manifest lesions was 8%. Streptococcus mutans was detected in 48.7% of the mothers and 6.7% of the children. Significant correlation could be seen between early introduction to sugar and caries prevalence in three year olds. No significant correlation was seen between Streptococcus mutans in children and introduction to sugar or caries prevalence.  Conclusion: In this small cohort of mother-child pairs, no correlation between children infected with S.mutans and mutans-positive mothers, as well as caries development in children could be seen.

<p> Quantitation by nuclear magnetic resonance (NMR) has been frequently done with integrals. The use of peak heights has been thought to be unreliable. The aim of this thesis is to examine the reliability of peak height method in achieving quantitative NMR measurements for small molecules such as water and sucrose.</p> <p> Isotope measurements have been traditionally done by isotope-ratio mass spectrometry. This is no doubt a highly sensitive technique for analyzing pure samples but the analysis of mixtures is not as straight-forward as it would be for the former. Ontario Hydro has encountered problems in measuring deuterium in DMSO/water mixtures. To solve the problem with NMR, an analytical method has been established to measure the deuterium content in waters and in DMSO/water mixtures. This involved testing a linear model for analyzing waters which were enriched or depleted with deuterium as well as applying the model to quantify DMSO/water mixtures. Both 1H and 2H NMR were employed. Satisfactory accuracy and precision of the results were obtained.</p> <p> For quantitative 13C work, the peak height method is often not recommended due to the variations in signal width, which is a result of varied T2 values and nuclear Overhauser enhancement (NOE). Sucrose molecules in cane sugar and beet sugar have different 13C isotopic ratios because they are synthesized by different photosynthetic pathways. To see the usefulness and limitation of the peak height method, 13C spectra of sucrose were acquired and the carbon peaks were quantified. Good precision was achieved but no predictable trend in the isotope difference could be found.</p> / Thesis / Master of Science (MSc)

Thesis (Ph.D. (Agriculture)) --University of Limpopo (Turfloop Campus), 2005 / Drying, grinding and sieving are commonly employed to facilitate the handling, storage of soil samples on which chemical, biological, and physical analyses are to be performed. These laboratory protocols have the potential to alter soil chemical characteristics and may result in unrealistic estimates of in situ chemical processes. The effect of laboratory soil sample preparation on level of extractable Ca, Mg, K, and P was determined. The analyses were done on laboratory prepared soil samples and compared with the characteristics of fresh soil samples (field-moist) for the same soils that were sampled in pairs of 20 per location of the four locations. Samples were collected at Tshiombho irrigation scheme, Dal water farm, Magoebaskloef pine tree farm and Syferkuil experimental farm. The results indicated that soil samples should be kept at their field moist status until experimental procedures are done. Concentration of most extractable ions for the two preparation methods correlated closely. However, grinding and air-drying increased P concentration by 1.3 to 1.55 times, and decreased the concentration of K by 2 to 2.5 times and this is caused by soil moisture depletion. According to the results, there should be different preparation methods for different extractable ions, Ca and Mg can be continued analysed on laboratory prepared soil samples but soil pH, K and P should be analysed on fresh soil samples. If such is not done, then the effects should be considered when interpreting the results for fertilizer recommendations. / NRF

In studies where the response variable is measured on a ratio scale, a ratio of means or medians provides a standardized measure of effect size that is an alternative to the popular standardized mean difference. Confidence intervals for ratios of population means and medians in independent-samples designs and paired-samples designs are proposed as supplements to the independent-samples t test and paired-samples t test. The performance of the proposed confidence intervals are evaluated in a simulation study. The proposed confidence interval methods are extended to the case of a 2 × m factorial design that includes propensity score stratification and meta-analysis as special cases. R functions that implement the recommended confidence intervals are provided in the Supplemental Material file, available in the online version of this article, and are illustrated with several examples.

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Yes / A novel particle isolation method for tissue samples was developed and tested using particle-doped peri-articular tissues from ovine cadavers. This enabled sensitivity of the isolation technique to be established by doping tissue samples of 0.25 g with very low particle volumes of 2.5 µm3 per sample. Image analysis was used to verify that the method caused no changes to particle size or morphologies. / The European Union's Seventh Framework Programme (FP7/2007–2013) under grant agreement no. GA-310477, LifeLongJoints.

This study focuses on emerging E. coil serotypes and has developed methods for the isolation and identification of non-0157 STEC and EPEC. A basal medium for the isolation of these pathogens was developed as well as a serogroup specific PCR assay for the detection of the 02 serogroup. These culture and molecular based techniques have proven to be valuable in the detection, identification, and epidemiological investigation of these groups of emerging pathogens. These methods were applied to 1) a farm study, whereby samples (faecal and soil) and 2) an abattoir study, whereby samples (hide and carcass) were analysed for the presence of non-0157 STEC and EPEC. Isolates were subsequently characterised in terms of serotype/serogroup and virulence markers. The data generated by this work has illustrated the extent of non-0157 STEC and EPEC contamination in the farm and abattoir environments, thus providing scientific background upon which control strategies may be based.

Dendrochronological collections include continuously expanding multi-taxon records of tree growth that encompass millennia and often offer irreplaceable sources of biological, environmental, and cultural information. Nevertheless, each departure of a scholar from the field—whether because of death, retirement, career change, shift in research priorities, or even move to a new institution—places collections in increased danger of being lost as viable resources. Without an organized and concerted effort to address outstanding and future issues of specimen curation, dendrochronology as a whole may become mired in the same trap that befalls many other scientific fields: collections apathy. Dendrochronological collections exist as a result of decades of effort and should function to support current and future scientific endeavors, education, and outreach, but cannot do so without adequate attention to their future. Intended as a ‘‘call to arms’’ this paper, focused on dendrochronology in the academic and public sector, aims to encourage discussion and, more importantly, to provide a foundation for and to instill a sense of urgency regarding long-term preservation of dendrochronological specimens.

The analysis of biological samples in clinical or research settings often requires measurement of analytes from complex and limited matrices. Immunoaffinity separations in miniaturized formats offer selective isolation of target analytes with minimal reagent consumption and reduced analysis times. A prototype capillary-based microfluidic system has been developed for immunoaffinity separations in biological matrices with laser-induced fluorescence detection of labeled antigens or antibodies. The laboratory-constructed device was assembled from two micro syringe pumps, a microchip mixer, a micro-injector, a diode laser with fused-silica capillary flow cell, and a separation capillary column. The columns were prepared from polymer tubing and packed under negative pressure with a stationary phase that consisted of biotinylated antibodies attached to streptavidin-silica beads. A custom software program controlled the syringe pumps to perform step gradient elution and collected the signal as chromatograms. The system performance was evaluated with flow accuracy, mixer proportioning, pH gradient generation, and assessment of detectability. A direct labeling/direct capture immunoaffinity separation of C-reactive protein (CRP) was demonstrated in simulated serum. CRP, a biomarker of inflammation and cardiovascular disease risk assessment, was fluorescently labeled in a one-step reaction and directly injected into the system. A quadratic calibration model was selected and precision and accuracy were reported. Parathyroid hormone was also analyzed by the direct capture approach, but displayed nonspecific binding of human plasma matrix components that limited the useful assay range. Capillary sandwich assays of CRP in human serum and cerebrospinal fluid were performed using both capture and detection antibodies. The detection antibody was labeled and purified offline to minimize signal from labeled matrix components. Four parameter logistic functions were used to model the data and precision and accuracy were evaluated. During the study, 250 nL injection volumes 2.0 µL/min flow rates were employed, minimizing sample and reagent consumption. The microfluidic system was capable of separating antigens from biological matrices and is potentially portable for patient point-of-care settings. Additionally, the flexible design of the separation capillary allows for the analysis of different clinical markers by changing the antibodies and the low assay volume requirements could lead to less invasive patient sampling techniques.LabVIEW version 7 or later is required to open the attached files.