Salicylic acid-binding protein 2 (SABP2) is essential for the establishment of systemic acquired resistance (SAR) in tobacco; SABP2's methyl salicylate (MeSA) esterase activity is required in healthy systemic tissues of infected plants to release the active defense phytohormone SA from MeSA, which serves as a long-distance signal for SAR. In the current study, we characterize a new gene family from Arabidopsis thaliana encoding 18 potentially active α/β fold hydrolases that share 32-57% identity with SABP2. Of 14 recombinant AtMES (MES for methyl esterase) proteins tested, five showed preference for MeSA as a substrate and displayed SA inhibition of MeSA esterase activity in vitro (AtMES1, -2, -4, -7, and -9). The two genes encoding MeSA esterases with the greatest activity, AtMES1 and -9, as well as AtMES7 were transcriptionally upregulated during infection of Arabidopsis with avirulent Pseudomonas syringae. In addition, conditional expression of AtMES1, -7, or -9 complemented SAR deficiency in SABP2-silenced tobacco, suggesting that these three members of the AtMES family are SABP2 functional homologs (orthologs). Underexpression by knockout mutation and/or RNAi-mediated silencing of multiple AtMES genes, including AtMES1, -2, -7, and -9, compromised SAR in Arabidopsis and correlated with enhanced accumulation of MeSA in the systemic tissue of SAR-induced plants. Together, the data show that several members of the AtMES gene family are functionally homologous to SABP2 and redundant for MeSA hydrolysis and probably SAR. These data suggest that MeSA is a conserved SAR signal in Arabidopsis and tobacco.

Systemic acquired resistance (SAR) is a state of heightened defense which is induced throughout a plant by an initial infection; it provides long-lasting, broad-spectrum resistance to subsequent pathogen challenge. Recendy we identified a phloem-mobile signal for SAR which has been elusive for almost 30 years. It is methyl salicylate (MeSA), an inactive derivative of the defense hormone, salicylic acid (SA). This discovery resulted from extensive characterization of SA-binding protein 2 (SABP2), a protein whose high affinity for SA and extremely low abundance suggested that it might be the SA receptor. Instead we discovered that SABP2 is a MeSA esterase whose function is to convert biologically inactive MeSA in the systemic tissue to active SA. The accumulated SA then activates or primes defenses leading to SAR. SABP2's esterase activity is inhibited in the initially/primary infected tissue by SA binding in its active site; this facilitates accumulation of MeSA, which is then translocated through the phloem to systemic tissue for perception and processing by SABP2 to SA. Thus, while SABP2 is not the SA receptor, it can be considered the receptor for the SAR signal. This study of SABPs not only illustrates the unexpected nature of scientific discoveries, but also underscores the need to use biochemical approaches in addition to genetics to address complex biological processes, such as disease resistance.

Thesis (MPH.) -- University of Limpopo, 2020 / Background: In South Africa, the Choice on Termination of Pregnancy Act (CTOP) (No. 92 of 1996) promotes a woman's reproductive right and choice to have an early, safe and legal abortion. Pregnancy termination among young women constitutes a public health problem particularly in South Africa where high prevalence of abortion has been recently recorded. HIV acquisition is increased two to four-fold during pregnancy, due to biological and behavioural factors including immunological changes, hormonal changes affecting the genital tract mucosa, higher frequency of unprotected sex and incident sexually transmitted infections (STIs) during pregnancy. There is a growing interest in exploring maternal mental health effects of unintended pregnancies. However, the evidence base from a small number of available studies is characterized by considerable variability, inconsistency and inconclusive findings. Therefore, the primary objective of this study was to investigate the prevalence of HIV and its association with termination of pregnancy at Seshego Zone 4 clinic in Limpopo Province. Methodology: A cross-section descriptive retrospective review study in which convenience sampling of the records of women who terminated pregnancies was used in this study. The key variable of interest in this study was HIV results and all patients records without evidence of HIV testing, and the associated results were excluded. A self-designed data extraction tool was used to extract the data from patients records and tool covered variables such as the age of the women, educational status, marital status, occupational status, year and month of termination of pregnancy, gestational age, parity, and gravidity, method of contraceptive used, HIV status, ARV and ARV regimens. Data analysis was done using the STATA statistical software version 12 for Windows (STATA Corporation, College Station, Texas). vi Results: The mean age was 24.98 years SD±14.4 and majority of women who terminated pregnancies were in the age group 20 – 24 years at 35.7% and the least number of women who terminated pregnancies were in the age groups ≥ 40 years and ≤ 14 years at 2.3% and 0.3% respectively. Majority of the women who terminated pregnancies had parity of 1 – 2 at 47.4% followed by parity of zero at 42.3% and 3 – 4 at 9.9%. Majority of the women who terminated pregnancies were in gravida 1 at 42.8% followed by those with gravida 2 at 27.1% and those who were pregnant between the 3rd and 4th time were 26.9%. There was a statistical significance difference (p<0.001) of the use of contraceptives by age groups and also in relation to parity and similarly to gravidity. The prevalence of HIV amongst women who terminated pregnancies in the current study was found to be 11.6% and this was high in 2018 at 10.5% followed by 2019, 2015 and 2016 at 10.3%, 9.2% and 9.1% respectively. The prevalence of HIV amongst women who terminated pregnancies increased with increasing level of education from 4.1% amongst women who had primary or no educational level the followed by 9,0% and 13.6% in women who had secondary and tertiary educational level respectively. The risk of women who terminate pregnancies being HIV positive in the current study increased significantly with increasing age as older women were 1.9 times more likely to be HIV positive as compared to younger ones (p=0.004) Conclusion: The findings of this study highlight the need to address the structural socio-economic drivers of the HIV epidemic among women of child-bearing age. Women of child-bearing age in this setting have large unmet reproductive health needs. Structural interventions, such as increasing contraceptive use which may be useful for reducing the burden of unplanned pregnancies. Key concepts Human immunodeficiency virus, Acquired immunodeficiency syndrome, Termination of pregnancy, Parity and Gravidity.

Background: Community acquired pneumonia causes 5,9% of deaths in elderly South Africans. Mortality rates are increased in those in whom initiation of therapy with an appropriate agent has been delayed. Whereas Mycoplasma pneumoniae and Legionella pneumophila are sensitive to the macrolides or tetracycline, they do not respond to the currently recommended first-line agents for community acquired pneumonia, penicillin or a cephalosporin. It was therefore necessary to assess the prevalence of exposure to these 2 organisms in the elderly in order to determine whether a modification in the recommendations may be justified. Methods: Study population and survey: Subjects were residents of 4 old age homes in Cape Town who were older than 60 years and willing to participate. Written consent was obtained, a demographic and medical history questionnaire was completed, and a sample of blood was drawn. Laboratory methods: The indirect fluorescent antibody tests (Zeus Scientific Inc, New Jersey, USA) were used to detect the presence of antibodies to Mycoplasma pneumoniae and Legionella pneumophila. Results: The participation rate in this study was high, with 88,4% (677/766) taking part. Seropositivity for both of these organisms was low. There were 17 participants (2, 51 %) with antibodies to mycoplasma (IgG only in 8, IgM only in 1, and both IgG and IgM in the remaining 8). Titres were low with only 1 IgM titre of 16, and only 3 IgG titres of 64. Antibodies to Legionella were demonstrated in only 9 participants (1,33%). All these titres were 128 or above. Conclusions: It is concluded that first-line therapy for community acquired pneumonia should adhere to the current guidelines published by the South African Pulmonology Society. There is no indication for the routine use of agents active against Legionella or mycoplasma. Clearly, these antibiotics should be introduced if specific pointers to infection with one of these organisms are found. Because of the low seropositivity rate, the indirect fluorescent antibody test for these 2 agents has a high specificity in this population. This may be of use in making a diagnosis in an acute infection Further studies are required to elucidate the immunological response to these organisms in elderly persons. A further survey should be done to determine the seropositivity rate to these agents in community dwelling elderly.

During the last several decades, venous thromboembolism (VTE) has been identified as a preventable health condition. The gaps in clinical practice have led to an increased incidence of VTE. The lack of using existing evidence-based VTE prevention guidelines in practice has limited the implementation of VTE risk assessment stratifications and affected the appropriateness and timeliness of addressing pharmacologic and mechanical prophylaxis. The purpose of the scholarly project was to educate practitioners on existing VTE prevention practice guidelines. The practice-focused question explored whether an educational learning activity on evidence-based VTE prevention guidelines improved the awareness, knowledge, and compliance with existing evidence-based VTE guidelines of practitioners that assess and treat patients at risk for VTE. The theoretical framework for the project was Lewin's change process theory. A total of 38 participants comprised registered nurses (82%), physicians (5%), nurse practitioners (2%), and nonclinical personnel (11%). A program evaluation was provided to determine the effectiveness of the project. The findings showed that practitioners participated in the learning activity to improve knowledge (48%), increase VTE awareness (43%), and would change the management and treatment of patients at risk for VTE (39%). Hospitalized patients at risk for VTE can benefit from the results of this project through a change in clinical practice that might decrease the incidence of VTE and potentially bring about social change by reducing the number of preventable deaths.

Philosophiae Doctor - PhD / In the decade since first identified, the Acquired Immunodeficiency syndrome (AIDS) has become a serious global disease. The nature of the Human Immunodeficiency Virus (HIV) that causes AIDS, whereby a carrier may be asymptomatic yet remain infectious, has enabled its dramatic spread. The number of AIDS cases is increasing exponentially, averaging a doubling time of between 8-15 months indifferent countries. Of the millions of HIV carriers, it is now estimated that all will eventually go on to develop full-blown AIDS and probably die within 15 years. Unlike other infectious diseases, there is currently no known vaccine or cure. Further, HIV is now virtually completely dependent on volitional sexual behaviours for transmission to occur. It is therefore an entirely preventable disease. However, since the behaviours that contribute to HIV-transmission are influenced by biological, psychological, and social factors, their alteration in line with safer sexual practices has been shown to be considerably complex and difficult. Intervention strategies that have relied on imparting knowledge about the disease have achieved limited success in influencing behaviour change. Unsafe sexual practices, and the risk of HIV-infection, often continue even when knowledge regarding prevention is adequate. It has therefore become apparent that other variables intrude which may mediate between knowledge acquisition, attitude formation, and consequent sexual behaviours. There appear to be no models which adequately explain the complexities in this area, and which enable adequate intervention strategies to be developed. The present study was undertaken to redress this problem, and to explore those variables that mediate in the area. Various psychological and social factors appear to be implicated in influencing sexual attitudes and behaviours. In order to adequately test the impact of psychosocial variables that were found to have significant associations in an exploratory study, a measuring instrument was developed. The AIDS Psychosocial Scale was statistically validated using content, frequency, factor, and reliability analyses and included psychological factors of self concept, defenses of denial, repression, and rationalisation, perceived empowerment in the form of locus of control and self efficacy, and the social factor of peer pressure susceptibility. The impact of these psychosocial variables on indices of knowledge, condom attitude, and sexual practices, and on other epidemiological variables was tested using a sample of students at the University of the Western Cape (n=308). Results indicated a number of correlational and causal links between variables, confirming the mediational role psychosocial factors have in influencing knowledge acquisition, attitude formation, and behaviour outcome. A profile of lower self concept, higher defenses, lower self-efficacy, more external locus of control, and higher peer pressure susceptibility emerged which was associated with poorer knowledge, more negative attitudes, and higher unsafe sex. Based on this study, a model of psychosocial mediation is developed and its implications for intervention strategies discussed.

Cancers that are deficient in BRCA1 or BRCA2 are thought to be hypersensitive to genotoxic agents because they cannot prevent or repair DNA double strand breaks, but observations in patients suggest this dogma may no longer agree with experiment. Here, we propose that single stranded DNA underlies the hypersensitivity of BRCA deficient cancers, and that defects in double strand break repair and prevention do not. Specifically, in BRCA deficient cells, ssDNA gaps developed because replication was not effectively restrained in response to stress. In addition, we observed gaps could be suppressed by either restored fork restraint or by gap filling, both of which conferred therapy resistance in tissue culture and BRCA patient tumors. In contrast, restored double strand break repair and prevention did not confer therapy resistance when gaps were present. Critically, double strand breaks were not detected after therapy when apoptosis was inhibited, supporting a framework in which double strand breaks are not directly induced by genotoxic agents, but instead are created by cell death nucleases and are not fundamental to genotoxic agents. Together, these data indicate that ssDNA replication gaps underlie the BRCA cancer phenotype, "BRCAness," and we propose are fundamental to the mechanism-of-action of genotoxic chemotherapy.

京都大学 / 0048 / 新制・課程博士 / 博士(社会健康医学) / 甲第20288号 / 社医博第77号 / 社新制||医||9(附属図書館) / 京都大学大学院医学研究科社会健康医学系専攻 / (主査)教授 川上 浩司, 教授 一山 智, 教授 伊達 洋至 / 学位規則第4条第1項該当 / Doctor of Public Health / Kyoto University / DGAM

No description available.

Original published work submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctorate of Philosophy in Virology. Johannesburg 2017. / Introduction: HIV-infected and HIV-exposed-uninfected children have a heightened susceptibility to some vaccine preventable disease. There is a paucity of data on immunogenicity of vaccines in these children, including HIV-infected children who are initiated on early antiretroviral therapy (ART). We evaluated the effect of maternal HIV-exposure and timing of ART in HIV-infected children on antibody responses to combined diphtheria-toxoid (DT) -tetanus-toxoid (TT)-whole cell pertussis (wP) and Haemophilus influenzae type b conjugate vaccine (HibCV); monovalent hepatitis B vaccine (HepB) and live-attenuated measles vaccine (MV). Methods: Samples obtained from children aged 6–12 weeks who had been enrolled into the CIPRA-SA study were analysed. Briefly, HIV-uninfected children born to HIV-uninfected (HIV-unexposed) and HIV-infected mothers (HEU). Additionally, we enrolled perinatally HIV-infected children with CD4+%≥25% randomized to deferred-ART (i.e. initiated when clinically or immunologically indicated per the then WHO recommended treatment criteria; ART-Def) or immediate-ART initiation (i.e. initiated on ART immediately upon confirmation of HIV-infection status at 4-10 weeks of age; ART-Immed). Children enrolled in the ART-Immed arm were further randomized to interrupt ART at one-year (ART/12m) or two-years of age (ART/24m). Additionally, a convenience sample of HIV-infected children with CD4+<25% initiated on immediate-ART was enrolled (ART-CD4+<25%). Children received a primary series of DTwP-HibCV/HepB at 6, 10 and 14 weeks of age; and MV at 40 weeks of age. Booster dose of DTwP and MV was given at 15-18 months of age. Sampling time-points were: prior to the first dose of vaccine, four weeks after the third dose (18 weeks age), 24 weeks after the third dose (39.3 weeks of age), at the time of the booster dose (15- 18 months age), two to four weeks after the booster dose and at 24 months of age. Samples were analysed for antibodies for DT, TT, PT, FHA, HepB measured by Luminex microbead-immunoassay; and MV antibodies were quantified by an indirect enzyme immunoassay. Results: Antibody kinetics and response to primary series of DTwP-HibCV/HepB: Pre-vaccination GMCs were higher in HIV-unexposed than HEU children for TT, but lower for HepB, DT and FHA. Post-vaccination, sero-conversion, sero-protection and GMCs were similar in HEU and HIV-unexposed children for all vaccines. Furthermore, GMCs were higher in HIV-unexposed for TT, DT, HepB and FHA than in ART-Immed children; and for TT, HepB and PT than in ART-Def children. Nevertheless, there was no difference in proportion of HIV-unexposed and HIV-infected children who developed sero-protective vaccine-specific antibody levels post-vaccination. The timing of ART initiation generally did not affect immune responses to vaccines between HIV-infected groups. Antibody kinetics and booster responses to DTwP-HibCV/HepB vaccines: Pre-booster GMCs were generally higher in HIV-unexposed than HIV-infected children for all vaccine epitopes. Post-booster and at 24 months of age the ART-Def group had lower GMCs (except to FHA), and were less likely to have sero-protective antibody levels compared to HIV-unexposed group. Also, post-booster and at 24 months of age, GMC were generally higher in HIV-unexposed than ART-Immed children, and a higher percentage of HIV-unexposed than ART-Immed children maintained antibody levels ≥1IU/ml to TT and DT at 24 months of age. The GMCs and percentage of children with sero-protective thresholds were similar pre-booster and at 24 months of age between HIV-unexposed and HEU children. Antibody kinetics and response to measles virus vaccine: At 7.3 weeks of age, the proportion with sero-protective titers was higher in HIV-unexposed (65.2%) compared to any HIV-infected group (range: 16.7% to 41.8%); but dropped to <17% in all Groups at age 19.6 weeks. Twenty-eight weeks following the first measles-vaccine, ART/12m were less likely to have sero-protective titers (79.3%) compared to HIV-unexposed (94.8%; p<0.001), ART-Def (95.7%; p=0.003) or ART/24m (92.1%; p=0.02). Although the proportion with sero-protective levels were similar between groups immediately post-booster dose, this was lower in HEU (79.6%; p=0.002) and ART/12m (80.3%; p=0.01) compared to HIV-unexposed (94.3%) 41-weeks later. Conclusion: Primary vaccination with DTwP-HibCV/HBV of HIV-infected children initiated on early-ART confers similar immunity compared to HIV-unexposed children. HIV-infected children had poor anamnestic responses, if ART was not initiated prior to primary vaccination. In contrast, the memory response and persistence of antibody to most vaccine epitopes were similar between HIV-unexposed and HEU children. Increased waning of vaccine induced immunity over a 24 month period in ART-Def, ART/12m and HEU children following MV booster-dose; indicating the need for further booster doses after two-years of age in these children. I recommend close monitoring of HEU children, as this group makes up most children born to HIV-infected mothers and what facets of the immune system have been impacted by maternal exposure to HIV. / MT2017