Components of human diets may influence the incidence of colorectal adenomas, by modifying exposure or susceptibility to DNA-damaging alkylating agents. To examine this hypothesis, a food frequency questionnaire was used to assess the diet of patients recruited for a case-referent study where biopsies of normal colorectal mucosa were collected during colonoscopy and subsequently analysed for DN...

Abasic (apurinic/apyrimidinic, AP) sites in DNA arise from spontaneous base loss or by enzymatic removal during base excision repair. It is commonly accepted that both classes of AP site have analogous biochemical properties and are equivalent substrates for AP endonucleases and AP lyases, although the relative roles of these two types of enzymes are not well understood. We provide here genetic...

The processing of covalent aflatoxin B1 (AFB1)-DNA adducts was investigated in confluent normal fibroblasts (NF) and xeroderma pigmentosum skin fibroblasts of Complementation Group A (XPA) following treatment with rat liver microsome-activated AFB1 for 30 min. Following rapid DNA isolation at slightly acidic pH by a new filter technique, more than 90% of the adducts corresponded to 2,3-dihydro-...

The N7 of purine nucleotides presents one of the most dominant metal ion binding sites in nucleic acids. However, the interactions between kinetically labile metal ions like Mg2+ and these nitrogen atoms are inherently difficult to observe in large RNAs. Rather than using the insensitive direct N-15 detection, here we have used (2)J-H-1,N-15]-HSQC (Heteronuclear Single Quantum Coherence) NMR ex...

Aflatoxin B2a (AFB2a) antiserum has been previously used in an enzyme-linked immunosorbent assay (ELISA) for the quantitation of AFB1 and AFB2a. The present investigation examined the reactivity of the antiserum toward those adducts and metabolites of AFB1 believed to play a major role in aflatoxicosis and carcinogenesis. 2,3-Dihydro-2-(N7-guanyl)-3-hydroxyaflatoxin B1 (AFB1-N7-Gua), the putati...

If G is a connected graph with vertex set V , then the degree distance of G, D′(G), is defined as ∑ {u,v}⊆V (deg u + deg v) d(u, v), where degw is the degree of vertex w, and d(u, v) denotes the distance between u and v. We prove the asymptotically sharp upper bound D′(G) ≤ 14 nd(n− d) 2 +O(n7/2) for graphs of order n and diameter d. As a corollary we obtain the bound D′(G) ≤ 1 27 n 4 + O(n7/2)...

Peridotite xenoliths, raised to the surface by alkaline basalts or kimberlites,provide us direct information on processes and composition of upper mantle. They are major source state stress,pressure temperature in deep thus a petrological geochemical that is generally not available Earth’s surface. Fresh spinel-lherzolite xenoliths exhibit protogranular components Tello volcano. The continental...