Increasing the Analytical Sensitivity by Oligonucleotides Modified with Para- and Ortho-Twisted Intercalating Nucleic Acids – TINA

The sensitivity and specificity of clinical diagnostic assays using DNA hybridization techniques are limited by the dissociation of double-stranded DNA (dsDNA) antiparallel duplex helices. This situation can be improved by addition of DNA stabilizing molecules such as nucleic acid intercalators. Here, we report the synthesis of a novel ortho-Twisted Intercalating Nucleic Acid (TINA) amidite utilizing the phosphoramidite approach, and examine the stabilizing effect of ortho- and para-TINA molecules in antiparallel DNA duplex formation. In a thermal stability assay, ortho- and para-TINA molecules increased the melting point (Tm) of Watson-Crick based antiparallel DNA duplexes. The increase in Tm was greatest when the intercalators were placed at the 5′ and 3′ termini (preferable) or, if placed internally, for each half or whole helix turn. Terminally positioned TINA molecules improved analytical sensitivity in a DNA hybridization capture assay targeting the Escherichia coli rrs gene. The corresponding sequence from the Pseudomonas aeruginosa rrs gene was used as cross-reactivity control. At 150 mM ionic strength, analytical sensitivity was improved 27-fold by addition of ortho-TINA molecules and 7-fold by addition of para-TINA molecules (versus the unmodified DNA oligonucleotide), with a 4-fold increase retained at 1 M ionic strength. Both intercalators sustained the discrimination of mismatches in the dsDNA (indicated by ΔTm), unless placed directly adjacent to the mismatch – in which case they partly concealed ΔTm (most pronounced for para-TINA molecules). We anticipate that the presented rules for placement of TINA molecules will be broadly applicable in hybridization capture assays and target amplification systems

Optimizing anti-gene oligonucleotide ‘Zorro-LNA’ for improved strand invasion into duplex DNA

Zorro-LNA (Zorro) is a newly developed, oligonucleotide (ON)-based, Z-shaped construct with the potential of specific binding to each strand of duplex DNA. The first-generation Zorros are formed by two hybridized LNA/DNA mixmers (2-ON Zorros) and was hypothesized to strand invade. We have now established a method, which conclusively demonstrates that an LNA ON can strand invade into duplex DNA. To make Zorros smaller in size and easier to design, we synthesized 3′–5′–5′–3′ single-stranded Zorro-LNA (ssZorro) by using both 3′- and 5′-phosphoramidites. With ssZorro, a significantly greater extent and rate of double-strand invasion (DSI) was obtained than with conventional 2-ON Zorros. Introducing hydrophilic PEG-linkers connecting the two strands did not significantly change the rate or extent of DSI as compared to ssZorro with a nucleotide-based linker, while the longest alkyl-chain linker tested (36 carbons) resulted in a very slow DSI. The shortest alkyl-chain linker (3 carbons) did not reduce the extent of DSI of ssZorro, but significantly decreased the DSI rate. Collectively, ssZorro is smaller in size, easier to design and more efficient than conventional 2-ON Zorro in inducing DSI. Analysis of the chemical composition of the linker suggests that it could be of importance for future therapeutic considerations

Blood pressure patterns in rural, semi-urban and urban children in the Ashanti region of Ghana, West Africa

BACKGROUND: High blood pressure, once rare, is rapidly becoming a major public health burden in sub-Saharan/Africa. It is unclear whether this is reflected in children. The main purpose of this study was to assess blood pressure patterns among rural, semi-urban, and urban children and to determine the association of blood pressure with locality and body mass index (BMI) in this sub-Saharan Africa setting. METHODS: We conducted a cross-sectional survey among school children aged 8–16 years in the Ashanti region of Ghana (West-Africa). There were 1277 children in the study (616 boys and 661 females). Of these 214 were from rural, 296 from semi-urban and 767 from urban settings. RESULTS: Blood pressure increased with increasing age in rural, semi-urban and urban areas, and in both boys and girls. The rural boys had a lower systolic and diastolic blood pressure than semi-urban boys (104.7/62.3 vs. 109.2/66.5; p < 0.001) and lower systolic blood pressure than urban boys (104.7 vs. 107.6; p < 0.01). Girls had a higher blood pressure than boys (109.1/66.7 vs. 107.5/63.8; p < 0.01). With the exception of a lower diastolic blood pressure amongst rural girls, no differences were found between rural girls (107.4/64.4) and semi-urban girls (108.0/66.1) and urban girls (109.8/67.5). In multiple linear regression analysis, locality and BMI were independently associated with blood pressure in both boys and girls. CONCLUSION: These findings underscore the urgent need for public health measures to prevent increasing blood pressure and its sequelae from becoming another public health burden. More work on blood pressure in children in sub-Saharan African and other developing countries is needed to prevent high blood pressure from becoming a major burden in many of these countries

Variations in the prevalence of point (pre)hypertension in a Nigerian school-going adolescent population living in a semi-urban and an urban area

<p>Abstract</p> <p>Background</p> <p>Hypertension has been shown to start in early life and to track into adulthood. Detecting adolescents with hypertension and prehypertension will aid early intervention and reduce morbidity and mortality from the disorders. This study reports the point-prevalence of the two disorders in a semi-urban and an urban population of school-going adolescents in Nigeria.</p> <p>Methods</p> <p>A total of 843 adolescents from two places of domicile were studied. Their blood pressures and anthropometric indices were measured using standard protocol. Point-hypertension and point-prehypertension were defined with respect to each subject's gender, age and height. The prevalence of the disorders was calculated and reported age-wise and nutritional status-wise.</p> <p>Results</p> <p>The prevalence of point-prehypertension in the semi-urban area was 22.2% (20.7% for girls and 23.1% for boys) while it was 25.0% (21.8% for girls and 29.2% for boys) in the urban area. The prevalence of point-hypertension was 4.6% (4.1% for girls and 4.8% for boys) in the semi-urban area and 17.5% (18.0% for girls and 16.9% for boys) in the urban area. Point-prehypertension was not detected among the thin subjects of both places of domicile. The prevalence of point-prehypertension was similar in both the urban and semi-urban areas among the subjects who had normal BMI-for-age, and over-weight/obese subjects respectively. From the semi-urban to the urban area, the prevalence of point-hypertension increased approximately 3-folds among thin and normal BMI-for-age subjects, and 10-folds among overweight/obese subjects. Systolic hypertension was more preponderant in both the semi-urban and urban areas.</p> <p>Conclusions</p> <p>The prevalence of both disorders is considerably high in the studied populations. Urgent pediatric public health action is needed to address the situation.</p