Acquired immunity in vertebrates is a major mechanism of the immune system, which enables the vertebrates to discriminate self and non-self The most important feature of acquired immunity is the major histocompatibility complex (MHC) restricted-cellular immune response. This involves several important elements including MHC molecules and T cell antigen receptor (TCR) complex. MHC molecules are glycoproteins that recognise and present self and foreign peptides to T-cells via the TCR, causing the T cell to proliferate and secrete cytokines. There is increasing evidence that peripheral T cells and MHC restricted cellular immune responses occur in all vertebrates. However, the exact nature of the TCR and MHC in lower vertebrates has still to be established. The aim of this thesis was firstly, to use the polymerase chain reaction (PCR) in conjunction with degenerative primers to the TCR β chain variable region (TCRBV) sequences of the homed shark to allow the amplification of the TCR-like genes from dogfish, Scyliorhinus canicula; secondly, to employ a similar strategy using degenerative primers to the banded houndshark MHC class-I α3 DNA sequence, to amplify MHC genes from S. canicula. Using the degenerative primers, four clones from dogfish genomic DNA were obtained. These clones showed homology to TCR genes of other species. The amino acid sequence of clone 2C144 showed homology to the TCRBV region of several species. The highest similarities include 51.7% with the honed shark TCRBV, 45.1% with human TCRBV, 41% with monkey TCRBV, 40.7% with bovine TCRBV and 38.8 and 37.5% with chimpanzee and rat TCRBV, respectively. The clone 6C43 also showed homology to the TCRBV genes of several species (similarity is between 21.1% to 23.9%). Another two clones (6C53 and 6C54) were identified that showed high homology to the TCR δ chain variable region (TCRDV) of other vertebrates with 45.7% identity to the honed shark TCRDV region, 43.2% identity to mouse TCRDV, 32.2% identity to porcine TCRDV region, and 30.7% identity to human TCRDV. The highly conserved residues in the other vertebrates TCR are present in these four clones as well, such as WYRQ37 and YY(F)C92 motifs. Southern blotting analysis with the putative TCRBV (2Cl44) and TCRDV (6C53 and 6C54) suggested that polymorphism existed between different fish. Northern blotting analysis with the probe 6C53 identified a transcript of approximately 2 kb in the spleen., lymphocytes and brain as well, with the probe 2C144 identified a transcript of approximately 2 kb in the lymphocytes of dogfish. The sequences of nine clones obtained using cDNA as a template from dogfish together with degenerative primers showed high homology to the membrane-proximal domain of the MHC class II α chain in several species. These clones exhibited a high degree of homology to the nurse shark MHC class II α chain (74.1%), zebrafish MHC class II α chain (52.8%), mouse MHC class II I-A (49.6%), rat MHC class II α chain (49.9%), bovine MHC class II DYα chain and DQα chain (52.7% and 44.9%, respectively), human HLA- DP, - DQα and -DRα chain (44.4%) respectively. The cysteine residues of the membrane-proximal domain are conserved in the dogfish, suggesting that it may have a similar tertiary structure to mammalian MHC class II proteins. A highly conserved tryptophan residue at position 121 was found in the dogfish and an N-linked glycosylation site was present at position 133, whilst in higher mammals it is usually found at position 118. The Southern blotting analysis using probe DM9 showed that there may be more than four loci of MHC class IIA in dogfish. These results suggest that the MHC class II, TCRB and TCRD genes are present in dogfish. The dogfish may have distinct T-cells, expressing either αlβ or γ/δ heterodimers. Conserved key residues in both MHC class IIA. TCRB and TCRD suggest that these genes may encode functional MHC class II, TCRB and TCRD molecules. The MHC restricted cellular immune response may be present in dogfish. Dogfish TCRB, TCRD and MHC class II genes show high homology with several species including human, rat, bovine and other fish species, which implies that the immunoglobulin (Ig) superfamily has evolved from a common ancestor.

No description available.

Diss. (sammanfattning) Linköping : Univ., 2001. / Härtill 5 uppsatser.

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains xxv, 449 p.; also includes graphics (some col.). Includes bibliographical references (p. 376-449). Available online via OhioLINK's ETD Center

Aflatoxin B1 and T-2 toxin are mycotoxins, which produce their immunotoxic effects by affecting nonspecific and acquired immunity in different species. The mechanisms of their immunotoxicity are still obscure. Cytokines are the key signaling molecules during the immune response. In this study, expression of macrophage-produced cytokines Interleukin-lα (IL-lα), tumor necrosis factor (TNF), and IL-6, and lymphocyte-produced cytokines IL-2, interferon y (IFNy), and IL-3 was measured at the mRNA and protein levels, after in vitro activation with mitogens in AFB1-and T-2-toxin-exposed mice. Significant changes in the organ weights, especially in the mice exposed to a high dose of T-2 toxin, and no effect in AFB1-exposed mice were observed. ConA-induced production of IL-2, IFNy, and IL-3 mRNA and protein levels in AFB1-exposed mice showed a decrease in low dose groups (significant for IL-2 mRNA), but no change at other doses. However, in T-2-toxin-treated animals, there was a significant induction of IL-2 and IFNy mRNA in high and low doses and of IL-3 mRNA at the medium dose. The protein levels of IL-2 and IFNy did not follow the mRNA levels in high dose and the protein levels of IL-3 were significantly increased in medium and low doses. LPS-induced IL-lα and TNF mRNA and protein levels in AFB1-exposed mice were suppressed at the high dose while mRNA levels of both cytokines were increased significantly in the low and medium doses. Low and medium doses of AFB1 also significantly decreased IL-lα protein levels and the high dose decreased IL-6 protein. In T-2 toxin-treated mice, no significant difference in mRNA levels of these cytokines was observed but a general pattern of significant suppression of their protein levels (except IL-lα at medium dose) showed that both toxins regulate the cytokine expression differently. Based on the above discussed results and others, AFB1 may alter cell-mediated immunity by affecting the communication between macrophages and T lymphocytes through inhibiting the macrophage-producing cytokines. T-2 toxin-induced immunosuppression may be due not only to the inhibition of macrophage-producing cytokines, but also to the lack of effector cells to respond to the cytokines (IL-2, IFNy, and IL-3).

No description available.

Thesis (Ph.D.(Paediatrics))--University of Pretoria, 2009. / Abstract in English and Afrikaans. Includes bibliographical references.

An immunoglobulin-fortified milk replacer and a subcutaneous (SC) injectable solution of immunoglobulins (Ig) were examined as methods of achieving passive immunity in neonatal calves. Bovine Ig, from abattoir blood, were purified by polyphosphate fractionation and ion-exchange chromatography. In experiment 1, carried out at Agriculture Canada Research Station, Agassiz, 37 colostrum-deprived Holstein-Friesian bull calves were allotted to one of four treatments. Col/WM calves were fed colostrum on day 1 and whole milk, days 2 - 42. MR-Nolg calves (control) were fed milk replacer with no Ig, days 1-42. MR-Hi/Lo calves were fed milk replacer with Ig at 50 mg/ml on day 1, and at 10 mg/ml, days 2 -21. MR-Hi/No calves were fed milk replacer with Ig at 50 mg/ml, day 1,'and with no Ig, days 2 - 21. From days 2 2 - 42, MR-Hi/Lo and MR-Hi/No treatment calves received milk replacer with no Ig. In experiment 2, carried out at the University Research Farm at Oyster River, 24 colostrum-deprived Holstein-Friesian bull calves were allotted to one of three treatments. The first two treatments were the same as for experiment 1, Col/WM and MR-Nolg fed for days 1-21. MR-Lo Inj calves were fed milk replacer with Ig at 10 mg/ml, days 1-21, and were also given a SC injection of Ig solution within the first 6 hours of life. For days 2-42, calves were fed WM or MR-Nolg, as per experiment 1. For both experiments, blood samples and calf weights were taken at birth, 24 & 48 hours of age, day 7 and weekly thereafter for six weeks. Diarrhea (scours) levels, rectal temperatures and general health of calves were recorded daily for the first three weeks as well. Experiment 1 survival at 6 weeks of age was 11 out of 11 calves for Col/WM treatment, 8 out of 8 calves for MR-Hi/Lo treatment, 7 out of 8 calves for MR-Hi/No and a significantly lower (P>0.05) 7 out of 9 calves for MR-Nolg. In experiment 2, survival was 7 out of 8 calves for both Col/WM and MR-Lo-Inj treatments and a significantly lower (P>0.05) 4 out of 8 calves for MR-Nolg treatment. Calves on MR-Hi/No had significantly higher diarrhea levels than the other three treatments over weeks one and four in experiment 1. In experiment 2, calves which did not receive any Ig had significantly higher diarrhea levels over weeks three and four than calves which received Ig. Experiment 1 average daily gains (ADG) were significantly higher for calves on Col/WM, MR-Hi/Lo and MR-Hi/No treatments than for calves on MR-Nolg at six weeks of age. In experiment 2, six week ADG were significantly higher for calves on Col/WM and MR-Lo Inj treatments than for MR-Nolg. For both experiments, serum Ig levels of calves on Col/WM were significantly higher than calves on the other treatments at 24 and 48 hours of age. MR-Hi/Lo, MR-Hi/No and MR-Lo Inj calves trended to higher serum Ig levels than MR-Nolg calves but were not significantly different. Calves which received Ig, from colostrum, the Ig-fortified milk replacer or a subcutaneous Ig injection, had higher survival rates, lower diarrhea levels, less antibiotic treatment and higher average daily gains than calves hot receiving any Ig. It was concluded that immunoglobulins, administered either orally or parenterally, are an effective, alternative method, for providing passive immunity in neonatal calves. / Land and Food Systems, Faculty of / Graduate

An emergency reaction is required in Africa because HIVIAIDS is a reality which may be regarded as a developing crisis and a catastrophe. Approximately a third of all women in the North-West Province are HIV positive. Because of their vulnerability against HIVIAIDS there arose a need for health service provision to the HIV positive woman to focus specifically on the reduction of the transmission of HIVIAIDS from mother to child. Mother to child transmission is the biggest cause of HIV infection among children. Almost all HIV positive children are infected during pregnancy, labour, childbirth or breastfeeding. Without the necessary preventative measures as many as 25-35% of the children of HIV positive mothers may be infected. The biggest percentage of infections, however, takes place during labour and the birth process. In first world countries the mother has access to choices and facilities to make an informed decision about antiretroviral therapy, as well as the method of birth. In the North-West Province not all these options and facilities are available, and therefore the knowledge and skills of midwives must be deployed to reduce vertical transmission of HIV during the intrapartum practice. It is important that midwives have the necessary knowledge about intrapartum practices and vertical transmission of HIV, in order to distinguish between risky and safe intrapartum practices. The purpose of this research was to determine whether midwives in the Southern region of the North-West Province have sufficient knowledge of intrapartum practices to reduce vertical transmission of HIV, as well as to determine the intrapartum practices in the Southern region of the North-West Province. The ultimate goals, then, were to determine how the national policy should be adapted and implemented in the Southern region of the North-West Province to reduce HIV transmission during intrapartum practices. A quantitive survey design was used. For the data collection a questionnaire and a control list were used. The questionnaire and the control list, which are adapted and based on literature, were submitted to research and subject specialists, after which they were adapted. Permission was obtained for this research from the Department of Health in the North-West Province, the ethics committee of the PU for CHE as well as each provincial hospital in the Southern region in the North-West Province to conduct the research. A purposeful availability sample of midwives working in the Southern region of the North-West Province was used and a random sample was used for auditing the obstetric records. A total of 31 midwives participated as respondents, and 401 obstetrical records were audited. Data analysis was performed by means of a frequency analysis, effect sizes and cross reference. Based on these findings it was concluded that the midwives do have basic knowledge regarding vertical transmission of HIV, but that this knowledge is not reflected in the intrapartum practice. There is uncertainty about certain aspects where the latest research about intrapartum practices are not implemented in practice. Recommendations were accordingly formulated for nursing education, research and practice. This research particularly focused on improving midwives' knowledge about intrapartum practices to reduce the vertical transmission of HIV, so that this knowledge may result in improved intrapartum practice. Recommendations are also made as to how the national policy may be adapted and implemented in the Southern region of the North-West Province. / Thesis (M.Cur.)--North-West University, Potchefstroom Campus, 2004.

An emergency reaction is required in Africa because HIVIAIDS is a reality which may be regarded as a developing crisis and a catastrophe. Approximately a third of all women in the North-West Province are HIV positive. Because of their vulnerability against HIVIAIDS there arose a need for health service provision to the HIV positive woman to focus specifically on the reduction of the transmission of HIVIAIDS from mother to child. Mother to child transmission is the biggest cause of HIV infection among children. Almost all HIV positive children are infected during pregnancy, labour, childbirth or breastfeeding. Without the necessary preventative measures as many as 25-35% of the children of HIV positive mothers may be infected. The biggest percentage of infections, however, takes place during labour and the birth process. In first world countries the mother has access to choices and facilities to make an informed decision about antiretroviral therapy, as well as the method of birth. In the North-West Province not all these options and facilities are available, and therefore the knowledge and skills of midwives must be deployed to reduce vertical transmission of HIV during the intrapartum practice. It is important that midwives have the necessary knowledge about intrapartum practices and vertical transmission of HIV, in order to distinguish between risky and safe intrapartum practices. The purpose of this research was to determine whether midwives in the Southern region of the North-West Province have sufficient knowledge of intrapartum practices to reduce vertical transmission of HIV, as well as to determine the intrapartum practices in the Southern region of the North-West Province. The ultimate goals, then, were to determine how the national policy should be adapted and implemented in the Southern region of the North-West Province to reduce HIV transmission during intrapartum practices. A quantitive survey design was used. For the data collection a questionnaire and a control list were used. The questionnaire and the control list, which are adapted and based on literature, were submitted to research and subject specialists, after which they were adapted. Permission was obtained for this research from the Department of Health in the North-West Province, the ethics committee of the PU for CHE as well as each provincial hospital in the Southern region in the North-West Province to conduct the research. A purposeful availability sample of midwives working in the Southern region of the North-West Province was used and a random sample was used for auditing the obstetric records. A total of 31 midwives participated as respondents, and 401 obstetrical records were audited. Data analysis was performed by means of a frequency analysis, effect sizes and cross reference. Based on these findings it was concluded that the midwives do have basic knowledge regarding vertical transmission of HIV, but that this knowledge is not reflected in the intrapartum practice. There is uncertainty about certain aspects where the latest research about intrapartum practices are not implemented in practice. Recommendations were accordingly formulated for nursing education, research and practice. This research particularly focused on improving midwives' knowledge about intrapartum practices to reduce the vertical transmission of HIV, so that this knowledge may result in improved intrapartum practice. Recommendations are also made as to how the national policy may be adapted and implemented in the Southern region of the North-West Province. / Thesis (M.Cur.)--North-West University, Potchefstroom Campus, 2004.