https://www.um.edu.mt/library/oar/handle/123456789/32898 2026-04-05T02:34:17Z https://www.um.edu.mt/library/oar/handle/123456789/33313 Title: Biological hazards of composting Abstract: The biological process of composting involves the aerobic breakdown of complex organic substrates by means of a succession of microorganisms to give an end product with properties similar to those of humus found in soils. The initial heating up stage involves a succession of bacteria whilst the final maturation stages of the compost are carried out by thermophilic actinomycetes and fungi, mainly Aspergillus fumigatus. This wide range of organisms, however can cause health problems to the people directly involved in the process. These hazards can range from irritations caused by dust dispersal, to Organic Dust Toxic Syndrome ( also referred to as Monday morning fever ) caused by bacterial endotoxins present in the respirable portion of the dust clouds; to the more serious but less frequent hypersensitivity reactions like extrinsic allergic alveolitis due to both the actinomycetes and Aspergillus fumigatus. The aim of this study is twofold. The first part is a quantitative assessment of Gram negative bacteria, their endotoxins, thermophilic actinomycetes and Aspergillus fumigatus at five selected points within the Municipal Solid Waste composting plant at Marsascala as compared to an uncontaminated background point. The second part studies the responses of plant operators to dust and bacterial insults using both a subjective questionnaire and simple lung function tests. Their questionnaire responses are then compared to an unexposed control group. Statistical analysis are carried out to assess the levels of contaminants within the plant vs the background and the responses of the more exposed employees to their environmental insults. Finally, a brief review is given on suitable protection measures that should be taken to reduce adverse health effects on the employees. Description: M.PHIL. 2000-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/32966 Title: In vivo expression of the G γ globin gene of foetal haemoglobin Abstract: Hb F Malta I (cx2GY2117 His-7Arg) is a stable and benign variant of Hb F found in 1.8% of Maltese newborn. It has been considered a valuable marker of the levels of in vivo expression of the human G γ globin gene and the parameters that control differential gene expression. Cord blood samples (n=6780) were analysed by Iso-Electric Focusing (LE.F.) and 1.8% were found to have a Hb F variant with a pI of 7.29 typical of Hb F Malta 1. The mean proportions of G γ Malta I in Hb F, quantified by reverse phase HPLC, were 0.26 ± 0.03 and 0.58 ± 0.06 in Hb F Malta I heterozygotes and homozygotes respectively. Analysis of the β globin gene cluster haplotype in Hb F Malta I homozygotes established that the Hb F Malta I allele occurs on a haplotype Va background (+ + - - - - -++- for the 5'ɛ Hinc IT, 5' G γ Apa I, 5' G γ Xmn I, G γ and A γ Hind III, Ψn and 3'Ψβ Hinc II, 5'β Hinf I, β Ava II and 3'β Barn HI sites respectively). The common Mediterranean haplotypes Va, IIIb, I and IT accounted for 66.2% of the wild-type alleles tested in Hb F Malta I heterozygotes. Another six haplotypes were also commonly found in Hb F Malta I heterozygotes and together accounted for another 20% of wild-type alleles tested. About 13% of wild-type alleles tested in Hb F Malta I hetcrozygotes had haplotypes that appeared only once in the cohort tested. Analysis of the association between polymorphic sites in the β globin gene cluster and G γ globin chain levels, in Hb F Malta I heterozygotes, showed that the 5'ɛ Hinc II, G γ and A γ Hind III, and 3'Ψβ Hinc II sites are linked to significant variations in the proportion of G γ Malta I and G γ globin chains in Rb F. Meanwhile, no particular haplotype in trans to the G γ Malta I allele was found to be associated with high or low G γ globin chain levels in Hb F Malta I heterozygotes. While the Xmn 1 sIte S' to the G γ globin gene was not found to be associated with significant variations in proportion of G γ globin chains in Rb F Malta I heterozygous infants, this site was found to be associated with variations in Hb F and G γ globin chain levels in a population of Maltese β-thalassaemia homozygotes. Description: M.PHIL. 2000-01-01T00:00:00Z