Radiation-induced mutagenicity and lethality in Salmonella typhimurium

The mutagenic and lethal effects of ionizing radiation on histidine-deficient auxotrophs of Salmonella typhimurium were studied to improve the understanding of radiation damage to DNA. The auxotrophs were divided into two groups - one which is sensitive to base-pair substitutions and another sensitive to frameshifts. These groups were composed of parent-daughter pairs in which the chemical mutagenicity enhancing plasmid, pKM101, is absent in the parent strain and present in the daughter. Co-60 ..gamma..-radiation and 250 kV x-rays were used to irradiate the bacteria. Irradiation of the frameshift - sensitive strains which carry the pKm101 plasmid doubled the absolute number of induced revertants whereas irradiation of the base-pair substitution sensitive strain which also carries the pKm101 plasmid produced nearly no change in the number of induced revertants. A nearly negligible effect on the mutation rate was observed for all parent strains. (ACR

?radiolysis of DNA in oxygenated aqueous solutions: Alterations at the sugar moiety

PubMed ID: 6975249On ?irradiation of DNA in N2O/O2-saturated aqueous solutions alterations at the sugar moiety are observed. In the present study three new lesions were recognized: (i) 2-deoxytetrodialdose bound via a phosphoric acid ester linkage to a (broken) DNA strand, (ii) 2-deoxypentos-4-ulose bound to DNA via one (or two?) phosphoric acid ester linkage(s), and (iii) 2-deoxy-D-erythro-pentose bound to DNA via two phosphoric acid ester linkages. Lesion (i) is directly connected with a DNA strand break. Lesion (ii) might be related to a DNA strand break if bound via only one phosphoric acid ester linkage, or has to be considered as an alkali-labile site if bound via two phosphoric acid ester linkages. Lesion (iii) results from base damage, when the damaged base is hydrolysed from the sugar. This lesion is an alkali-labile site which turns into a strand break on alkali treatment. Attempts have been made to quantify these lesions. A lower limit of sugar damage (including lesions observed in preceding studies, but not lesion (iii)) of G = 0·25 has been estimated. © 1981 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted

The Prevalence and Comorbidity Rates of ADHD Among School-Age Children in Turkey

Objective: The aim of the present study was to explore the prevalence and comorbidity rates of ADHD in a community sample of school-age children. Method: Participants were 1,508 children aged 6 to 14 years. Parents and teachers of each child completed the Turgay Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV) Disruptive Behavior Disorders Rating Scale (T-DSM-IV-S). Screen-positive cases were interviewed using the Schedule for Affective Disorders and Schizophrenia for School-Age Children–Present and Lifetime Version (K-SADS-PL). Diagnoses were based on DSM-IV criteria. Results: The prevalence rate of ADHD was 8%. Children from extended families had extremely high rates (46.4%) of ADHD. Sixty percent of children with ADHD had one or more comorbid diagnoses. The most common comorbidities were learning disorders (35.7%) and oppositional defiant disorder (22.6%). Conclusion: The prevalence and comorbidity rates of ADHD in school-age children in Turkey are similar to those found in previous studies in other countries. © 2015 SAGE Publications

Cooperative effects of field traffic and organic matter treatments on some compaction-related soil properties

Soil compaction is a common problem of mineral soils under conventional tillage practices. Organic matter addition is an efficient way of reducing the effects of field traffic in soil compaction. The aim of this study was to investigate the effects of number of tractor passes (one, three, and five) on depth-dependent (0–10 and 10–20 cm) penetration resistance, bulk density, and porosity of clay-textured soil (Typic Xerofluvent) under organic vegetable cultivation practices in the 2010–2013 growing seasons. Fields were treated with farmyard manure (FYM, 35 t ha−1), green manure (GM; common vetch, Vicia sativa L.), and conventional tillage (CT). The number of tractor passes resulted in increases in bulk density and penetration resistance (CT > GM > FYM), whereas the volume of total and macropores decreased. The maximum penetration resistance (3.60 MPa) was recorded in the CT treatment with five passes at 0–10 cm depth, whereas the minimum (1.64 MPa) was observed for the FYM treatment with one pass at 10–20 cm depth. The highest bulk density was determined as 1.61 g cm−3 for the CT treatment with five passes at 10–20 cm depth; the smallest value was 1.25 g cm−3 in the FYM treatment with only one pass at 0–10 cm depth. The highest total and macropore volumes were determined as 0.53 and 0.16 cm3 cm−3 respectively at 0–10 cm depth for the FYM treatment with one pass. The volume of micropores (0.38 cm3 cm−3) was higher at 0–10 cm depth for the FYM treatment with three passes. It can be concluded that organic pre-composted organic amendment rather than green manure is likely to be more efficient in mitigating compaction problems in soil

Chloramphenicol-induced bone marrow injury: possible role of bacterial metabolites of chloramphenicol

To explore the potential role of some bacterial metabolites of chloramphenicol (CAP) in CAP-induced hematotoxicity, we examined their cytotoxic effects on bone marrow cells in vitro using a number of cytotoxicity parameters. Among the metabolites tested, dehydro-CAP (DHCAP) and p-nitrophenyl-2-amino-3 hydroxypropanone-HCI (NPAP) were more toxic than CAP. DHCAP was at least as toxic as nitroso-CAP. At concentrations of less than or equal to 10(-4) mol/L, DHCAP caused total irreversible inhibition of myeloid colony (CFU-GM) growth and 80% inhibition of DNA synthesis in human bone marrow. Incubation of human bone marrow cells with 10(-4) mol/L nitroso-CAP or DHCAP for 24 hours resulted in 75% and 65% cell death respectively. Although DHCAP was 10- to 20-fold more cytotoxic than CAP, it was only one third as effective in inhibiting mitochondrial protein synthesis, indicating that DHCAP exerts its toxic effect by alternate mechanisms. The cytotoxicity of DHCAP and its relative stability, compared to the unstable nitroso CAP, suggest that this bacterial metabolite of CAP, and possibly others, may play a significant role in CAP-induced hematotoxicity