Laserska izravna dvofotonska fotoliza guanina u DNK

Nanosecond laser-induced oxidative lesions at guanines within DNA were investigated using sequencing gel electrophoresis analysis. Strong sequence-specific lesions on guanines were revealed by either Fpg or piperidine treatments and assigned to 8-oxoG and oxazolone, respectively. It was shown that both the biphotonic ionization process and the chemical reactivity of the radical cation (G+) are dependent on the DNA sequence. The former were explained by the occurrence of energy and charge migration phenomena, while the latter in terms of local DNA hydration peculiarities.Istraživali smo lomove DNK izazvane nanosekundnim laserskim impulsima primjenom gel elektroforeze za određivanje nizova. Otkrili smo snažne nizovno specifične lomove kod guanina djelovanjem sa Fpg ili piperidinom i oni se pripisuju 8-oxoG odnosno oxazolonu. Pokazali smo da su i dvofotonski ionizacijski proces i kemijska reaktivnost radikala kationa (G+) nizovno ovisni. Prvi se objašnjava selenjem energije i naboja, a drugi kao posebnosti lokalnog hidriranja DNK

Mjerenje prinosa međusustavnog prijelaza s4U u tRNA vremenski-razlučenim izbjeljivanjem

The rare base 4-thiouridine (s4U), present in various transfer RNA (tRNA) molecules from Escherichia coli, occupies usually the strategically important 8 th position between the double helices of the acceptor and the dihydrouridine stems of the cloverleaf. This unusual base is largely used as an intrinsic build-in probe for RNA conformational and RNA(DNA)–protein interaction studies through triplet excited state photochemistry related to covalent adducts formation. Here, by applying laser transient absorption saturation spectroscopy, we measured the intersystem crossing yield ϕST and the excited triplet state absorption εT−T of s4U within tRNA. While the incorporation of s4U in tRNA induced appreciable changes in the latter, no important variation of the intersystem crossing yield was observed, which is in contrasts with the published data.Rijetka baza 4-thiouridine (s4U), koju nalazimo u raznim prijenosnim molekulama RNA (tRNA) Escherichie coli, obično uzima strateški važan 8. položaj između dviju zavojnica primatelja i dihidrouridinskih stapki lista djeteline. Ta se neobična baza najviše rabi kao unutarnja ugradbena proba za proučavanje interakcija konformalne RNA s RNA(DNA)–proteinima preko fotokemije tripletnog uzbuđenog stanja, povezanog sa stvaranjem kovalentnih adukata. U ovom smo radu primjenom laserske prijelazne apsorpcijske spektroskopije sa zasićenjem mjerili prinos međusustavnih prijelaza ϕST i apsorpciju tripletnog stanja εT−T s 4U u tRNA. Dok ugrađivanje s4U u tRNA uzrokuje prilične promjene u tRNA, nismo opazili promjene prinosa međusustavnih prijelaza, što nije u skladu s objavljenim rezultatima

Učinci UV zračenja visokog intenziteta na izdvojen i s dna interkaliran etidium bromid

High-intensity picosecond laser flash photolysis has been used for investigating ethidium bromide (EtBr). The quantum yield of primary photoproducts as a function of the laser intensity has been obtained. DNA intercalated EtBr and water solutions of EtBr have been investigated. The results have been compared. They show that two-photon processes are predominantly responsible for generation of hydrated electron (eaq-). The primary processes of DNA photosensitization have also been discussed.Istraživali smo etidium bromid (EtBr) pomoću pikosekundne bljeskovne fotolize velikog intenziteta. Određeni su kvantni prinosi fotoprodukata u ovisnosti o intenzitetu laserskog snopa. Istraživao se je EtBr u vodenoj otopini i interkalirani s DNA. Rezultati se uspoređuju i oni pokazuju da pretežno dvofotonski procesi tvore hidrirane elektrone eaq-. Raspravljaju se također primarni procesi fotosenzitiranja DNA

Antimicrobial consumption and resistance in adult hospital inpatients in 53 countries:results of an internet-based global point prevalence survey

Summary: Background: The Global Point Prevalence Survey (Global-PPS) established an international network of hospitals to measure antimicrobial prescribing and resistance worldwide. We aimed to assess antimicrobial prescribing and resistance in hospital inpatients. Methods: We used a standardised surveillance method to collect detailed data about antimicrobial prescribing and resistance from hospitals worldwide, which were grouped by UN region. The internet-based survey included all inpatients (adults, children, and neonates) receiving an antimicrobial who were on the ward at 0800 h on one specific day between January and September, 2015. Hospitals were classified as primary, secondary, tertiary (including infectious diseases hospitals), and paediatric hospitals. Five main ward types were defined: medical wards, surgical wards, intensive-care units, haematology oncology wards, and medical transplantation (bone marrow or solid transplants) wards. Data recorded included patient characteristics, antimicrobials received, diagnosis, therapeutic indication according to predefined lists, and markers of prescribing quality (eg, whether a stop or review date were recorded, and whether local prescribing guidelines existed and were adhered to). We report findings for adult inpatients. Findings: The Global-PPS for 2015 included adult data from 303 hospitals in 53 countries, including eight lower-middle-income and 17 upper-middle-income countries. 86 776 inpatients were admitted to 3315 adult wards, of whom 29 891 (34·4%) received at least one antimicrobial. 41 213 antimicrobial prescriptions were issued, of which 36 792 (89·3%) were antibacterial agents for systemic use. The top three antibiotics prescribed worldwide were penicillins with β-lactamase inhibitors, third-generation cephalosporins, and fluoroquinolones. Carbapenems were most frequently prescribed in Latin America and west and central Asia. Of patients who received at least one antimicrobial, 5926 (19·8%) received a targeted antibacterial treatment for systemic use, and 1769 (5·9%) received a treatment targeting at least one multidrug-resistant organism. The frequency of health-care-associated infections was highest in Latin America (1518 [11·9%]) and east and south Asia (5363 [10·1%]). Overall, the reason for treatment was recorded in 31 694 (76·9%) of antimicrobial prescriptions, and a stop or review date in 15 778 (38·3%). Local antibiotic guidelines were missing for 7050 (19·2%) of the 36 792 antibiotic prescriptions, and guideline compliance was 77·4%. Interpretation: The Global-PPS showed that worldwide surveillance can be accomplished with voluntary participation. It provided quantifiable measures to assess and compare the quantity and quality of antibiotic prescribing and resistance in hospital patients worldwide. These data will help to improve the quality of antibiotic prescribing through education and practice changes, particularly in low-income and middle-income countries that have no tools to monitor antibiotic prescribing in hospitals. Funding: bioMérieux

Spin-Dependent Level Density in Interacting Boson-Fermion-Fermion Model of the Odd-Odd Nucleus 196 Au

Abstract. The level density of the odd-odd nucleus 196 Au is investigated in the interacting boson-fermion-fermion model (IBFFM) which accounts for collectivity and complex interaction between quasiparticle and collective modes.The IBFFM spin-dependent level densities show high-spin reduction with respect to Bethe formula.This can be well accounted for by a modified spin-dependent level density formula