Thesis (M.S.P.H.)--University of Michigan, 1940.

No description available.

Dissertation submitted in partial compliance with the requirements for the Master's Degree in Technology: Homoeopathy, Technikon Natal, 2001. / The purpose of this study was to determine the effect of the homoeopathic remedies Phytolacca decandra 12CH and Phytolacca decandra 200CH on the incidence of acute clinical mastitis, on the somatic cell count and on the butterfat, protein and lactose levels of composite milk samples obtained from dairy cows. It was hypothesised that the remedy would have an effect on the incidence of acute clinical mastitis, on the somatic cell count and on the butterfat, protein and lactose levels of composite milk samples obtained from the two respective treatment groups in the dairy herd used A placebo-controlled double blind study design was used. The trial group consisted of252 Jersey cows from a farm in the Underberg district of KwaZulu- Natal, South Africa. These cows were ranked according to age before being randomly divided into three groups consisting of 84 lactating cows each. The random allocation of treatments in this manner ensured an even spread of treatments across all age classes and lactation number. The three groups were painted with different colours of enamel paint to ensure easy and accurate dispensing of medicine and placebo. All identifiable variables were the same for the three groups for the duration of the 100-day study . The homoeopathic remedies Phytolacca decandra 12CH, Phytolacca decandra 200CH, and the placebo' were supplied in granules in plastic sachets that were randomised and colour coded by an independent Homoeopath. Dispensing took place after milking while the cows were being fed and was done by the person responsible for the feeding. Five millilitre medicated or unmedicated granule doses were dispensed into the dry feed by matching the colour code on the container of the granules of placebo or verum with that of the cow and then sprinkling the granules over the dry food with a 5ml-measuring spoon. Composite milk samples were obtained the day before treatment commenced to obtain baseline readings for the whole test population. Sampling occurred on day 1,35,70 and 100. The milk samples were analysed at Taurus Central Laboratory to determine values for somatic cell count, butterfat, protein and lactose on the day of the milk recording . The data from 191 cows from the test population was used after selection criteria were applied. There were 65 cows in the Phytolacca decandra 200CH, 67 cows in the Phytolacca decandra l2CH, and 59 cows in the placebo group. All cases of acute clinical mastitis were recorded for the test population, / M

Mini-Dissertation submitted in partial compliance with the requirements for the Master's Degree in Technology: Homoeopathy, Technikon Natal, 2002. / The purpose of this research was to evaluate the efficacy of a homoeopathic complex of Phytolacca decandra 200CH, Bryonia alba 30CH and Silicea terra 30CH in the treatment of bovine mastitis. The efficacy of the complex was evaluated in terms of its effect on reducing the Somatic Cell Count (SCC) as well as its effect on reducing the total number of clinical cases occurring within the herd on treatment. The aim of trying to reduce the SCC is the fact that it is related to the quality of the milk produced, the higher the SCC the lower the quality and yield of the milk produced and thus the lower the monetary return on the sale of such milk. It is also related to the volume of milk produced as the higher the SCC the lower the quantity of milk produced. The number of cases of clinical mastitis is also an important economical consideration, as there are a number of costs associated with each case including short and long-term losses in production as well as the cost of treatment and management of infected animals / M

A dissertation submitted in partial compliance with the requirements for the Master's Degree in Technology: Homoeopathy, Technikon Natal, 1997. / The purpose of this study was to determine the efficacy of homoeopathic nos ode therapy as a prophylaxis for bovine mastitis. It was hypothesised that the nos ode would decrease the somatic cell counts in milk samples taken from the experimental group and hence the incidence of clinical and subclinical mastitis. A placebo-controlled double-blind experimental design was chosen. The sample comprised 69 Friesland cows selected from a dairy farm in the Karkloof area of KwaZulu-Natal and was divided randomly into two groups of approximately equal size. Each group was tagged, thus easily identified for treatment purposes. During the trial the two groups intermingled freely, and were therefore exposed to the same external influences. The medication and placebo were provided in identical 50 ml bottles, each labelled with a code corresponding to one of the groups. For each treatment, five millilitres from each bottle were / M

Subclinical mastitis remains the dominant form of mastitis affecting dairy cattle, and is responsible for the greatest economic losses associated with mastitis in dairy herds in the major dairy producing countries. Mastitis control has relied on a series of well established management practices that have led to significant improvements in mastitis prevalence and milk quality measures over the past 3 decades. Changes in pathogen prevalence, including the shift in absolute and relative importance of pathogens such as Escherichia coli, Klebsiella spp. and Streptococcus uberis combined with the ongoing importance of Staphylococcus aureus, highlight the need for continued research to evaluate mastitis control practices. This dissertation examines targeted antimicrobial treatment of chronic subclinical mastitis during lactation as a control measure implemented in herds that have applied standard mastitis control practices. Treatment of subclinical mastitis caused by the major gram-positive mastitis pathogens Staphylococcus aureus, Streptococcus uberis, and Streptococcus dysgalactiae in dairy herds is examined. Methods include predictive modeling of the effects of lactation therapy using a deterministic state-transition model of pathogen transmission dynamics, and evaluation of lactation treatment in a negative controlled clinical field trial. Concepts put forward include the distinction between direct and indirect effects of mastitis control practices and the value of molecular diagnostics to improve our understanding of mastitis epidemiology and the impact of control programs. Results obtained from predictive modeling indicate that overall positive population level effects of lactation therapy would be realized for herds that have successfully implemented practices that reduce pathogen transmission. A novel finding was the prediction that under management scenarios with high pathogen transmission rates treatment of subclinical mastitis will have little impact on the proportion of infected quarters and no positive population level effect in reducing new infection rates. In a field trial, positive direct and indirect effects of treatment of S. aureus mastitis were observed suggesting benefits of lactation therapy targeting this pathogen. Potential benefits were off-set by the frequent finding of post treatment infections which resulted in no improvement in somatic cell count of treated cows compared to untreated controls. Lactation therapy of S. uberis and S. dysgalactiae mastitis resulted in cure proportions and duration of infection did not differ from spontaneous cure of untreated controls and there was limited evidence of an effect of treatment on rates of new infection. A unique finding was the identification of an association between Coxiella burnetii shedding and subclinical mastitis in dairy cattle. It is concluded from this research that treatment of subclinical mastitis during lactation may be justified under specific conditions, and it is recommended that dairy farm managers and their advisors should not routinely implement lactation therapy of subclinical mastitis without careful consideration of the potential benefits and risks.

The pathogenesis of the bovine environmental pathogen Streptococcus uberis has been extensively studied, but it remains incompletely understood. The organism produces a surface protein capable of binding lactoferrin (Lbp), originally identified as an M-like streptococcal protein. We hypothesized that Lbp may play a role as a virulence factor. Structural similarity and amino acid sequence homology of Lbp to Mrelated proteins of Group A streptococci suggested a possible functional similarity between Lbp and M-like proteins, which are involved in evasion of host antibacterial defenses, adhesion to host epithelial cells and intracellular invasion by the bacteria. Alternatively, high-affinity binding of the abundant iron-chelating component of the host milk (lactoferrin) suggests that Lbp of S. uberis might play role in iron acquisition by the bacterium. Finally, Lbp might serve as a receptor for signal transduction in the bacterial cell or alter host cell signalling during infection, when the bacteria with surface-bound lactoferrin adhere to or invade the host epithelial cells. In order to test the hypothesis that Lbp is a virulence factor of S. uberis, a mutant strain of S. uberis unable to express the lactoferrin-binding protein was generated and the role of the protein was studied in comparative analyses of the mutant and the parent strains. The results of our study indicated that unlike many streptococcal M-like proteins, the lactoferrin-binding protein of S. uberis did not appear to play a role in overcoming host innate and acquired immune antibacterial responses. Both S. uberis and its lbp mutant were ingested by bovine blood neutrophils and were similar in their ability to survive in fresh bovine blood regardless of the presence either of lactoferrin or of anti-Lbp antibodies. Lbp did not promote bacterial adhesion to host epithelial cells and it was not essential for the internalization of the bacteria by host epithelial cells, since both S. uberis and lbp mutant were found capable of adhering, invading, intracellular survival and intracellular growth when the bacteria were co-cultured with bovine mammary epithelial cells. No significant differences in numbers of adherent or internalized bacteria per host cell were found between wild type and lbp mutant cells. S. uberis requirements for iron were determined to be low and Lbp was not essential for iron acquisition by the organism from iron-saturated lactoferrin. To study the role of Lbp in bacterial virulence during infection of bovine mammary glands, dairy cows in the second half of their lactation periods were challenged with the wild type S. uberis and with the lbp mutant. The results of in vivo infection suggested that expression of Lbp by the bacteria was not essential for colonization of the host mammary gland and that expression of Lbp was not associated with differences in severity of mastitis or with different levels of shedding of the bacteria by infected animals. To study the role of Lbp in signal transduction, differential bacterial cellular protein phosphorylation in the presence of bovine lactoferrin was analyzed. Since no differences in protein phosphorylation profiles were detected between S. uberis and the lbp mutant, it was concluded that Lbp is probably not a part of a classical bacterial twocomponent signalling pathway. However, we demonstrated that the expression of host genes potentially involved in cell morphogenesis, motility and signal transduction was regulated depending on the expression of Lbp by S. uberis. Down-regulation of the expression of selected host genes was verified by quantitative reverse transcription PCR. Putative iron responsive elements were identified in mRNA of several of these genes. Down-regulation of these genes in the cells overloaded with ferric iron was demonstrated by RT PCR. These results indicate that Lbp of S. uberis may interfere with host cellular signalling pathways by inducing perturbations in the cell iron status. This suggests that Lbp of S. uberis may be a virulence factor, playing a role in signal transduction or in the regulation of gene expression in host cells.

The pathogenesis of the bovine environmental pathogen Streptococcus uberis has been extensively studied, but it remains incompletely understood. The organism produces a surface protein capable of binding lactoferrin (Lbp), originally identified as an M-like streptococcal protein. We hypothesized that Lbp may play a role as a virulence factor. Structural similarity and amino acid sequence homology of Lbp to Mrelated proteins of Group A streptococci suggested a possible functional similarity between Lbp and M-like proteins, which are involved in evasion of host antibacterial defenses, adhesion to host epithelial cells and intracellular invasion by the bacteria. Alternatively, high-affinity binding of the abundant iron-chelating component of the host milk (lactoferrin) suggests that Lbp of S. uberis might play role in iron acquisition by the bacterium. Finally, Lbp might serve as a receptor for signal transduction in the bacterial cell or alter host cell signalling during infection, when the bacteria with surface-bound lactoferrin adhere to or invade the host epithelial cells. In order to test the hypothesis that Lbp is a virulence factor of S. uberis, a mutant strain of S. uberis unable to express the lactoferrin-binding protein was generated and the role of the protein was studied in comparative analyses of the mutant and the parent strains. The results of our study indicated that unlike many streptococcal M-like proteins, the lactoferrin-binding protein of S. uberis did not appear to play a role in overcoming host innate and acquired immune antibacterial responses. Both S. uberis and its lbp mutant were ingested by bovine blood neutrophils and were similar in their ability to survive in fresh bovine blood regardless of the presence either of lactoferrin or of anti-Lbp antibodies. Lbp did not promote bacterial adhesion to host epithelial cells and it was not essential for the internalization of the bacteria by host epithelial cells, since both S. uberis and lbp mutant were found capable of adhering, invading, intracellular survival and intracellular growth when the bacteria were co-cultured with bovine mammary epithelial cells. No significant differences in numbers of adherent or internalized bacteria per host cell were found between wild type and lbp mutant cells. S. uberis requirements for iron were determined to be low and Lbp was not essential for iron acquisition by the organism from iron-saturated lactoferrin. To study the role of Lbp in bacterial virulence during infection of bovine mammary glands, dairy cows in the second half of their lactation periods were challenged with the wild type S. uberis and with the lbp mutant. The results of in vivo infection suggested that expression of Lbp by the bacteria was not essential for colonization of the host mammary gland and that expression of Lbp was not associated with differences in severity of mastitis or with different levels of shedding of the bacteria by infected animals. To study the role of Lbp in signal transduction, differential bacterial cellular protein phosphorylation in the presence of bovine lactoferrin was analyzed. Since no differences in protein phosphorylation profiles were detected between S. uberis and the lbp mutant, it was concluded that Lbp is probably not a part of a classical bacterial twocomponent signalling pathway. However, we demonstrated that the expression of host genes potentially involved in cell morphogenesis, motility and signal transduction was regulated depending on the expression of Lbp by S. uberis. Down-regulation of the expression of selected host genes was verified by quantitative reverse transcription PCR. Putative iron responsive elements were identified in mRNA of several of these genes. Down-regulation of these genes in the cells overloaded with ferric iron was demonstrated by RT PCR. These results indicate that Lbp of S. uberis may interfere with host cellular signalling pathways by inducing perturbations in the cell iron status. This suggests that Lbp of S. uberis may be a virulence factor, playing a role in signal transduction or in the regulation of gene expression in host cells.

No description available.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1934. / Typescript. With this is bound: The biological characters of the Streptococcus commonly associated with mastitis (Str. agalactiae) / By Mildred A. Engelbrecht. Reprinted from Cornell veterinarian, vol. XXV (Oct. 1935), p. 313-333. Includes bibliographical references (leaves 57-59).