Soul of the Jukskei River: The Extent of Bacterial Contamination in the Jukskei River in Gauteng Province, South Africa.

River water quality is an important health issue as the water is utilised for drinking, domestic and agricultural use in developing countries. This study aimed to investigate the effect water from a major city has on the water quality of the Jukskei River that daylights in Johannesburg, South Africa. The river water samples were analysed for physio-chemical properties, microbiology, antibiotic resistance of bacterial isolates, genetic markers, and potentially toxic metals. Data analysis revealed increased electrical conductivity, total dissolved solids, and turbidity since 2010. Total Coliform and Escherichia coli detected were above the South African water quality guidelines for domestic, recreational, and irrigation purposes. Additionally, sodium, zinc, nickel, lithium, and lead exceeded the guidelines in domestic, recreational, and irrigation water. Pathogenic strains of E. coli (aEPEC, EHEC, EIEC, and EAEC) were isolated from the water. Various other potentially pathogenic organisms that have been implicated as causes of gastro-intestinal, and a wide range of other diseases, were also detected and demonstrated multiple levels of resistance to antibiotics tested. The results show that the river water is a potential health threat to downstream users. These results will feed into the environmental management action plan for Water for the Future (NGO group).

Studies on the inhibition of Moloney murine leukemia virus reverse transcriptase by N-tritylamino acids and N-tritylamino acid-nucleotide compounds.

N-Acylated derivatives of 8-(6-aminohexyl) amino-adenosine-5 '-phosphate were prepared and studied with regard to their effect on DNA synthesis by the Moloney leukemia virus reverse transcriptase. N-palmitoyl and N-nicotinyl derivatives and bis-8-(6-aminohexyl) amino-5'-AMP inhibited the enzyme partially using poly (rA).oligo d(pT)(16-18) as template-primer with [(3)H]dTTP. In order to increase hydrophobicity in the acyl component tethered to the 8-(6-aminohexyl) amino group on the adenine nucleotide, N-trityl-L-phenylalanine and the N-trityl derivatives of the o, m, and p-fluoro-DL-phenylalanine were initially examined for inhibition of the enzyme using the above template-primer system. The compounds all inhibited the reverse transcriptase with IC(50) values of approximately 60-80 microM. However, when N-trityl-m-fluoro-DL-phenylalanine was coupled to the nucleotide 8-(6-aminohexyl) amino-adenosine-5'-phosphate, the inhibitory activity of this compound increased significantly (IC(50) = 5 microM).

Development of a reproducible procedure for plasmid DNA encapsulation by red blood cell ghosts.

OBJECTIVE: The binding and encapsulation of [3H] pGL3 luciferase reporter plasmid DNA by red blood cell (RBC) ghosts, intended as a vehicle for transfection and ultimately for gene therapy, were studied using two methods for DNA compaction. METHODS AND RESULTS: In the first approach, DNA was compacted through binding electrostatically to poly-L-lysine. Complexes were constructed to have a slight negative charge. Experimentally, it was found that a high percentage of binding was to the outside of the resealed RBC ghosts. An alternative approach using polyethylene glycol6000 at a final concentration of 15% (weight/volume) was used to collapse [3H] pGL3 DNA in the presence of 0.025M MgCl2. Addition of the reagents, premixed with DNA, to a pelleted suspension of RBC ghosts followed by a short incubation and then addition of 1.5 M NaCl to restore tonicity, resulted in resealing of the ghosts. Uptake of [3H] pGL3 DNA by the ghosts was approximately 20% of the input amount of DNA. Further work showed that 60-70% of the DNA was inside the resealed ghosts and largely present in the supercoiled form. At no stage was any freezing and thawing used. CONCLUSION: Transfection studies have demonstrated that pGL3 DNA carrying the luciferase gene is successfully transferred from RBC ghosts to recipient HeLa cells in culture under mild fusion conditions.

Low concentrations of chlorpromazine and related phenothiazines stimulate gene transfer in HeLa cells via receptor-mediated endocytosis.

Chlorpromazine and related phenothiazine antipsychotic compounds at the low concentration of 10(-5) M stimulated luciferase pRSVL DNA uptake and expression in HeLa cells. On the other hand, chloroquine at a 10(-5) M was without effect at this low concentration. However, at the higher normally used concentration of 10(-4) M (100 microM), chloroquine strongly stimulated luciferase expression and activity. Unfortunately, at 10(-4) M, the phenothiazines were toxic to the cells and could not be tested at this concentration. Further experimental work was carried out to elucidate the mechanism of action of phenothiazines and chloroquine on DNA uptake and expression. Interaction of [3H] pBR 322 DNA with chlorpromazine, perphenazine, and chloroquine was studied using these compounds as their free bases dissolved in chloroform, followed by their impregnation onto Whatman No. 1 filter paper discs. Both phenothiazines on filter paper discs bound [3H] pBR 322 DNA to a far greater extent than chloroquine. The method of assay (free base) suggests that the major contribution to binding is through intercalation. A further possible assay for studying the interaction of phenothiazines and chloroquine made use of the ethidium bromide/calf thymus DNA intercalation method. Intercalated calf thymus (CT) DNA complexes with ethidium bromide (EB) were examined for possible dissociation into free DNA and EB on the addition of either chloroquine. SO4 or chlorpromazine.HCl (soluble salts). Partial dissociation was observed with both compounds. Further experiments on the stability of pBR 322 DNA-polylysine complexes were also carried out using an alternative method of assay. Chloroquine (10(-2)-10(-4) M) and chlorpromazine (10(-4) M) did not bring about a dissociation of [3H] pBR 322 DNA-polylysine(200) complexes when reactions were studied by nitrocellulose filter assays to measure released double-stranded DNA. The results indicate that chlorpromazine and related phenothiazines stimulate luciferase DNA uptake expression at 10(-5) M. Chloroquine at this concentration had practically no effect on expression of luciferase activity. Further studies of chloroquine and chlorpromazine on their interaction with plasmid DNA as well as DNA-polylysine complexes are reported.