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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
571

Virus removal during conventional drinking water treatment

Rose, Joan Bray. January 1985 (has links)
The isolation of viruses from treated drinking water has raised concerns that water treatment methods may not always adequately insure the removal of viruses from water designated for human consumption. The isolation of enteroviruses and rotavIruses from treated drinking water in a distribution system and at a water treatment plant has been previously reported. Isolation of viruses from drinking water that met recommended levels of coliform bacteria, chlorine and turbidity. The question is raised as to whether or not current drinking water standards ensure safe drinking water. The isolation of enteroviruses and rotaviruses from treated drinking water In a distribution system and at a water treatment plant. This study reports the results of a more extensive investigation on the removal of naturally occurring viruses by water treatment processes including prechlorination/clarification, filtration, and chlorination at a fullscale water treatment plant. The removal of enteroviruses and rotaviruses was studied at a full scale 205 mgd water treatment plant involving chemical clarification, sand filtration and chlorination. Enteric viruses, as well as coliphages, indicator bacteria, physical and chemical variables were measured in water samples taken at each stage of the drinking water treatment facility. Linear intercorrel ations were analyzed for all the variables. The numbers of standard plate count bacteria and coliphage were positively correlated to the presence of enteroviruses in the raw water while coliphage counts were positively correlated to the presence of rotaviruses in the finished water. Samples were taken during the dry and rainy seasons. During the dry season, it was found that reduction of enteroviruses and rotaviruses averaged 81% and 93%, respectively, for the complete treatment process and were the least efficiently removed as compared to the other microorganisms. The greatest reduction of enterovIruses occurred during pre-chlorination/flocculation and filtration, while a significant reduction of rotav I ru ses occurred during prechlorination/ flocculation and final chlorination. Enteroviruses or rotaviruses occurred in 24% of the finished water samples containing chlorine levels of >0.2 mg/L, and meeting coliform bacteria (1/100 ml) and turbidity (1 NTU) standards. During the rainy season removals were found to be far less efficient for all the variables and rotaviruses were isolated from all finished water samples. The results of this study indicate that finished water having measurable levels of free residual chlorine and meeting standards for col iform bacteria, and turbidity cannot be assumed to be virus free.
572

Histopathological, biological and molecular characteristics of the pathogenic Spiroplasma penaei isolated from the hemolymph of infected Pacific white shrimp, Penaeus vannamei

Heres, Allan Alberto January 2009 (has links)
Biological and molecular characteristics of the pathogenic mollicute, Spiroplasma penaei, isolated from the hemolymph of infected Pacific white shrimp, Penaeus vannamei, were investigated. The doubling times of a S. penaei were 6.13 h (2% NaCl) and 3.43 h (no salt) under aerobic conditions, and 6.63 h (2% NaCl) and 3.22 h (no salt) under anaerobic conditions. Small diffuse white colonies with granular centers, surrounded by small satellite colonies that appeared embedded in the agar matrix, were detected on solid M1D medium (2% Noble agar) under aerobic conditions at 28°C. The genome size of the S. penaei was 1778 Kb, as determined by pulsed-field gel electrophoresis using undigested DNA. Reduction of virulence of S. penaei was not detected in serial passage 24 and 76 isolates but passage 131 isolate was attenuated as indicated by the number of surviving shrimp and histological findings of challenged P. vannamei. Toxicity was not detected in supernatant fractions of M1D medium cultures of S. penaei isolates. The most predominant host responses to the S. penaei reference isolate and to serial passage isolates were hemocytic nodules and hemocytic infiltration observed in hematoxylin and eosin-stained histological sections. Transmission electron microscopy of the lymphoid organ of experimentally infected P. vannamei depicted S. penaei without cell wall and free in the cytoplasm of lymphoid organ cells. The lesions observed in histological sections were verified by in situ hybridization using a digoxigenin (DIG)-labeled probe specific to the spiralin gene of Spiroplasma spp. Evolutionary relationship trees, based on five partial DNA sequences of 16S rDNA, 23S rDNA, 5S rDNA, gyrB, rpoB genes and two complete DNA sequences of 16S-23S and 23S-5S ISR, were constructed using the distance-based Neighboring-Joining method with Kimura-2-parameter substitution model. The NJ trees based on all DNA sequences investigated in this study positioned S. penaei in the Citri-Poulsonii clade and corroborates the observations by other investigators using the 16S gene. Pairwise genetic distance calculation between sequences of spiroplasmas showed S. penaei to be closely related to S. insolitum and distantly related to Spiroplasma sp. SHRIMP from China.
573

The spatial population dynamics of house mice (Mus musculus domesticus) with reference to the potential transmission of zoonoses

Pocock, Michael James Orlando January 2001 (has links)
No description available.
574

The effect of cytomegalovirus infection on the susceptibility of target cells to lysis by natural killer cells

Fletcher, Jean Margaret January 2001 (has links)
No description available.
575

Hur sjuksköterskor kan bidra till följsamhet av basala hygienrutiner inom kommunal vård och omsorg

Öhman, Louisa January 2014 (has links)
Background: Basic hygiene is an important measure to prevent healthcare associated infections, save patients’ lives, and reduce economic costs for health care. Healthcare associated infections are a threat to patient safety. In community care persons who are the care takers are a risk group and nurses must make sure that basic hygiene procedures are followed. Method: Literature studies with descriptive design, article search in databases Cinahl and PubMed. The results found are based on twelve chosen articles. Aim: To describe factors related to adherence to basic hygiene and how nurses in community care can help to improve compliance with these procedures. Results: In the nursing staff and leadership in health care interest in and the understanding of basic hygiene is described as being of most importance. Lack of knowledge of the meaning of patient care cleanliness, negative attitudes and non-existing availability of necessary tools and heavy workload had a negative impact. Intensified education and making sure that equipment is available as well as the application of standardized methods, were found to be prerequisite for adherence to basic hygiene routines. Conclusion: Nurses can contribute to improved adherence to basic hygiene routines by promoting education, positive attitudes, a positive adaption of the physical environment, strategic structuring of the workload, and standardized methods, applying basic hygiene routines, being part of and promoting increased interaction in nursing care. Suggestions for future studies is to implement web-based courses, updating courses and training in basic hygiene routines in the workplace. That may increase knowledge, understanding and awareness of the application of basic hygiene routines hence leading to improved nursing care and enhancing patient safety.
576

What is the optimum diet for asymptomatic HIV-infected people (AHIV)? : a public health approach / Averalda Eldorine van Graan

Van Graan, Averalda Eldorine January 2007 (has links)
OBJECTIVE: The main aim of this thesis was to investigate the role of nutrition during "early" HIV-infection in African women. METHODS: Data reported in this investigation formed part of two cross-sectional studies, the THUSA and Mangaung studies. The Mangaung study investigated women and, therefore, the sub-sample of the THUSA study was chosen accordingly. The data of the two studies were kept and analysed separately. The investigation consisted of 1040 women from the THUSA study, aged between 15 and 90 years of which 120 (11.5%) were HIV infected. The Mangaung study comprised of 488 women aged between 25 and 44 years of which 248 (51%) women were infected. Demographic data, anthropometric measurements, health outcome variables and habitual nutrient intakes by a quantified food frequency questionnaire were used. The SPSS statistical package (version 14.0; SPSS Inc., Chicago, Illinois, 2005) was used to analyse data. Descriptive statistics were done expressing variables as means, medians, standard deviations (SD), standard errors (SE) and confidence intervals (CI). An analysis of variance (ANOVA) was done to test for significance between the HIV-infected and non-infected groups in both studies. Partial correlations were done in the infected and non-infected groups to determine associations between dietary / nutrient intake, anthropometry and the biological health variables. In the THUSA study we controlled for age, education level, degree of urbanization and alcohol intake and in the Mangaung study for age, education level and alcohol intake. Nutrient intakes of both infected and non-infected women above and below median values as well as in the first and fourth quartile of total cholesterol (TC) and albumin distribution were compared to assess the role of nutrients in the observed decreases in TC and albumin of HIV-infected women. RESULTS AND DISCUSSION: The dietary intakes of the HIV-infected women in both the studies did not differ significantly from the non-infected women. Total serum cholesterol, albumin, fibrinogen and blood pressure were significantly lower in the HIV-infected women in both the THUSA and Mangaung studies. The non-infected THUSA women with lower serum cholesterol levels (than the median) had significantly lower intakes of percentage energy from fat (25.2 versus 26.4%, p ≤0.027), percentage energy from total protein (11.6 versus 12.1%, p≤0.000), animal protein (25.6 versus 27.7g, p≤0.005), and significantly higher intakes of plant protein (32.2 versus 29.4g, p≤0.002) and fibre (16.9 versus 15.89 p≤0.029). There were no significant differences observed in the nutrient intakes in the infected women with serum cholesterol levels above and below the median. In the Mangaung study no significant nutrient intake differences were observed in both of the HIV-infected and non-infected women with lower and higher than the median TC levels. In the THUSA study, higher intakes of fat (percentage energy) were close to significant (27.3 versus 24.5%, p≤0.053) in the infected women with higher (than the median) albumin levels. In the non-infected group with higher albumin levels, significant differences were observed in percentage energy from fat (26.6 versus 24.9%; p≤0.001) protein (12.2 versus 11.6%; p≤0.001) and carbohydrate (62.8 versus 65.2%; p≤0.000). Higher intakes of saturated fat (SATFAT) (17.7 versus 16.1g, p≤0.008), monounsaturated fats (MUFAT) (19.3 versus 17.4g, p≤0.004) as well as higher intakes of animal protein (28.5 versus 24.4g, p≤0.000) were observed in the group with higher than the median levels of serum albumin. In the Mangaung study the HIV-infected women (with higher than the median serum albumin levels), had significantly higher intakes of energy (13 275 versus 11 622 kJ, p≤0.022), polyunsaturated fatty acids (32.3 versus 17.3g, p≤0.036), dietary cholesterol (412.9 versus 344.5mg, p≤0.043) and plant protein (42.3 versus 35.3g, p≤0.008). No differences were observed in the non-infected women. The further analyses, comparing the dietary intakes in both studies of infected and non-infected women with TC and albumin levels in the first and fourth quartiles, showed that in the THUSA study, non-infected women with lower TC levels had significantly lower intakes of protein (% of total energy), total fat (% of total energy) and vitamin B12 and significantly higher intakes of total energy (TE), plant protein, total carbohydrate, % TE from carbohydrate, dietary fibre, added sugar and thiamine. In the infected women saturated fatty acids (SATFAT), calcium and the fat ratio (polyunsaturated/saturated ratio) differed significantly between women with TC levels in the first and the fourth quartile. A significant higher intake of riboflavin was seen in the non-infected women from Mangaung with TC levels in the fourth quartile, while significant higher intakes of energy, total protein, animal protein, total fat, SATFAT, MUFAT, total carbohydrate, phosphorus, chromium and iodine was seen in the infected women with TC levels in the fourth quartile. These results suggest that a more "westernized" diet with higher intakes of energy, and animal derived foods (SATFAT and calcium) could have protected against the detrimental decreases in TC observed in HIV infection. Significant differences were observed in the intakes in the non-infected THUSA women who had serum albumin in the first and fourth quartiles. lntakes in percentage energy from protein and fat, animal protein, total fat, SATFAT, MUFAT, calcium, zinc, vitamin C and fat ratio, were significantly lower in the women with albumin levels in the first quartile. Significantly higher carbohydrate intakes were observed in the women who had serum albumin levels in the first quartile. In the Mangaung study, significant differences were seen in the intakes between infected women who had serum albumin levels in the first and fourth quartiles. lntakes of total energy, protein, fat, MUFAT, SATFAT, carbohydrate, magnesium, zinc, chromium, biotin, pantothenic acid and iodine were significantly lower in the infected women with serum albumin levels in the first quartile. In the non-infected women significantly lower intakes of calcium were observed in the group who had serum albumin levels in the first quartile compared to those who had serum albumin levels in the fourth quartile. These results also suggest that a more "westernized” diet was associated with higher albumin levels in HIV-infected women. CONCLUSION: It is well known that nutrition has an integral part to play in the care of people living with HIV/AIDS (PLWHA). Maintaining proper nutrition, weight and immune function is thought to delay disease progression, prolong the asymptomatic phase and improve survival. These analyses suggest that the "prudent" diet generally regarded as an optimal diet for prevention of non-communicable diseases, may not be the optimal diet for PLWHA. The overall analyses therefore suggest that a more "westernized" diet, higher in fat and protein could be more beneficial to asymptomatic HIV-infected women compared to that of a more "prudent" diet. As these studies were not primarily designed to investigate HIV and nutrition, the role of a higher energy, fat and animal protein intake ("western" diet) in asymptomatic HIV warrants urgent investigation. / Thesis (Ph.D. (Nutrition))--North-West University, Potchefstroom Campus, 2007.
577

A comparison of the factors which influence infection control in paediatric wards in England and Thailand

Wichaikull, Susheewa January 2011 (has links)
Acquiring an infection during a hospital stay is a hazard for patients throughout the world. Over 1.4 million people worldwide are suffering from infections acquired in hospital. Five to ten per cent of patients admitted to modern hospitals in developed countries acquire one or more infections, whereas patients in developing countries have a higher risk, around two to twenty times this figure. Paediatric patients, especially neonates and infants, have an additional risk of infection because of their compromised immune system. The purpose of this study was to explore the factors which contribute to the spread of infection among children in paediatric wards in a developed and a developing country: England and Thailand. Method: An ethnographic approach was utilised to identify practices which promote or prevent the spread of infection in each country. Purposive sampling was employed to recruit ten nurses in England and ten nurses in Thailand. Ethical approval was obtained from De Montfort University (DMU), National Research Ethics Service and the ethical approval committee in Thailand. Nonparticipant observations and semi-structured interviews were the main methods of obtaining data in clinical settings. Data from the observations and interviews were transcribed and coded using thematic content analysis. Results: Hospitals in Thailand and England faced the same problems regarding attitudes, values and beliefs which contribute to infection control difficulties in children, particularly poor hand hygiene. Good attitudes and beliefs will promote good practice. Moreover, education and training can raise perceptions and promote good practice. However, in terms of different cultures and circumstances, the key factors explaining different implementations between the two countries are resources, lifestyle, and religion. Conclusion: Even within the same hospital, different backgrounds including education, cultures, policies and support result in different factors which impact on paediatric patients. Individuality and personal responsibility for infection control practice are the most significant factors influencing compliance with best practice.
578

Infections and childhood cancer in Malawi

Mutalima, Nora January 2007 (has links)
The causes of childhood cancers are not well understood. That infections are believed to play an important role in childhood cancer development is of particular interest in sub-Saharan Africa, where infectious diseases are common. The objectives of this thesis were to identify childhood cancers associated with HIV, malaria, EBV and HHV-8, and to investigate child and maternal factors associated with Burkitt lymphoma and Kaposi sarcoma. In Blantyre, Malawi, 305 children diagnosed with cancer and 212 of their mothers, were recruited. Risk factor data were collected using a brief questionnaire and blood samples tested for infections. Case-control analyses were conducted to compare 148 Burkitt lymphoma cases and 22 Kaposi sarcoma case with a control group comprising 104 children with cancers other than those known to be associated with HIV. The prevalence of HIV was 6% among children with Burkitt lymphoma and 2% in controls (OR=12.4, 95% CI 1.3 to 116.2). Tumour risk increased with increasing litres of antibodies against EBV and malaria. In comparison with those who had low titres against both EBV and malaria, the highest risk of Burkitt lymphoma was among those with high titres against both infections (OR=13.2, 95% CI 3.8 to 46.6). Reported use of mosquito nets was protective against Burkitt lymphoma. The prevalence of HIV was 81% among children with Kaposi sarcoma (OR=762.7, 95% CI 44 to 13376), and risk increased with increasing HHV-8 antibodies. Prevalence of infections was also examined among children with other cancer types and no associations were identified, although the number of cases was small. Few maternal factors were found to be associated with cancer in children. This research demonstrates that infections play a particularly important role in increasing the risk of Burkitt lymphoma and Kaposi sarcoma in children in sub- Saharan Africa. Prevention or early treatment of these infections may be vital in the control of childhood cancer.
579

Molecular characterisation of the interaction of microbes with the insulin pathway

Nisr, Raid Bahr January 2012 (has links)
Exposure to microorganisms is considered an environmental factor which can contribute to diabetes mellitus via cytotoxicity or autoimmune responses against pancreatic cells. Firstly, the effects on rat insulinoma pancreatic β-cell line of secondary metabolites pyrrolnitrin (Burkholderia spp), phenazine compounds (Pseudomonas aeruginosa and Burkholderia spp) were investigated. Both compounds separately showed significant cytotoxicity after 24 h and at concentrations of 10 & 100 ng/ml potentiated insulin gene transcription, Ca2+ content and glucose-stimulated insulin secretion (GSIS). Furthermore, the outward membrane current was inhibited by phenazine (100 ng/ml) or pyrrolnitrin (10 or 100 ng/ml). Secondly, the capacity of 45 microbial species to bind insulin was screened in order to assess how common insulin binding was amongst microorganisms Burkholderia multivorans, B. cenocepacia and Aeromonas salmonicida bound insulin. A genomic library of B. multivorans was constructed in λ Zap Express and screened successfully for insulin binding recombinants. Recombinant phagemids p1 & p2 were excised, p1, encoded an insulin binding protein (IBP1 30 kDa) with homology to the iron complex siderophore receptor. For p2, two IBPs were detected at 20 & 30 kDa (IBP2 & IBP3), representing an intracellular and outer membrane peptide transporter. Comparison of IBP1 and human insulin receptor (HIR) produced 6 linear epitopes, and for IBP2 & IBP3 produced 3 epitopes. Thirdly, glutamic acid decarboxylase GAD65 is a major pancreatic autoantigen contributing to autoimmune diabetes. To assess the likelihood that microorganisms possess epitopes that mimic regions on GAD, 45 microbial species were tested for homology. This was facilitated by purifying recombinant GAD protein which was used to produce GAD antiserum. Four E. coli cross-reacting proteins were identified using mass spectrometry, outer-membrane protein A, formate dehydrogenase, superoxide dismutase and DNA starvation protein. Epitopes occurred at the C-terminal region of GAD65 (residues 419–565), a region previously reported to be targeted by autoantibodies. This study suggests that pyrrolnitrin and phenazine are cytotoxic to pancreatic β-cells and B. multivorans IBPs linear epitopes may be diabetogenic, particularly in patients with cystic fibrosis related diabetes (CFRD) who suffer a long term infections with Pseudomonas and Burkholderia species. Furthermore, microbial GAD epitopes could potentially induce an autoimmune response leading to diabetes.
580

Roles of Clostridium difficile cell wall and flagellar proteins in pathogenicity and innate immunity

Dehlawi, Saied Waheed January 2012 (has links)
The number of cases of Clostridium difficile infection (CDI) has been increasing globally. CDI is the main cause of nosocomial diarrhoea, which may be life-threatening in complicated cases, and also costs the health care societies millions of pounds annually. The predominant types and their resistance to antibiotics have been changing and one of the major selective pressures which causes this is antimicrobial use. Although much is known about the role of the toxins in pathogenesis of CDI, the role of immunogenic cell wall components is unclear. They may play a role in colonisation and pathology and a study of these could clarify the infection process. It is therefore important to study the immune responses against these bacterial wall components from different strains and their effects on stimulation of leukocytes to produce cytokines and chemokines. This study was divided into four parts: 1. An epidemiological study to determine frequencies of the predominant types of C. difficile, thus 140 C. difficile isolates from surgical patients and their environment during 2009 were investigated to define their PCR ribotype. This utilised capillary sequencing gel electrophoresis for their analysis. 2. The determination of antimicrobial susceptibility to six antibiotics (ampicillin, erythromycin, tetracycline, metronidazole, moxifloxacin and vancomycin) was assessed and MIC determination by agar dilutions. 3. Investigation of host immunity to molecules with conserved molecular patterns. Surface-layer proteins (SLPs), lipocarbohydrate (LC) and flagellar proteins were separated and purified from five ribotypes of C. difficile (001, 002, 027, 078 and106) predominant in Scotland. a) The immune responses to these molecules were assessed by ELISA by exposing serum of patients and healthy donors and measuring specific IgG levels. b) Innate immunity was investigated by distinguishing responses of a macrophage cell line (THP1) to the above molecules. Induction of interleukins (IL)-1β, IL-6, IL- 8, IL-10 and IL-12 interleukins and TNF-α was detected by ELISA. In this study 15 different ribotypes were identified. The most frequent were 001, 020, 106 ribotypes (52.8%, 7.4% and 5.7%), respectively, while 13 isolates could not be assigned a ribotype. However, all isolates were sensitive to vancomycin, metronidazole and moxifloxacin, but 74.28% of isolates were resistant to erythromycin. The IgG level against bacterial antigens (SLPs, LC and flagella proteins) in donors’ serum showed almost normal distribution to all antigens from the different ribotypes and the sensitivity of the assays was increased by raising the concentration of antigens. Levels to SLPs were generally the highest, but the flagellar protein exceeded the SLPs of the 027 ribotype. The donors, controls, patients and carrier sera gave similar results. The greatest induction of interleukins was obtained using 50μg of antigen with the THP-1 cells activated with 50ng of PMA. The highest induction of all antigens was for IL-10. The highest values for the control LPS was with IL-12. But the best effect for SLPs of 027 was for IL-10 (109.1ng/ml), while the weakest for TNF for SLPs of 027 (4.7ng/ml). In general the IL-1β, IL-6, IL-8 and TNF concentrations ranged from 4.7-60ng/ml for all antigens and in contrast IL-12 and IL-10 average ranged 11- 109.1ng/ml. To conclude, the prevalence of C. difficile and their antibiotic susceptibility are constantly changing. IgG antibodies to SLPs and flagellar proteins from the hypervirulent ribotype 027 were highest in the community and hospitalized individuals. The molecules of conserved molecular patterns are immunogenic with various levels of response in the monocytic THP1 cells. SLPs were best in inducing interleukins. Flagellar proteins from 027 ribotypes accompanied SLPs in IL-10 induction levels. Consequently SLPs and flagellar proteins from 027 ribotypes appeared the best immunogenic bacterial molecules.

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