Gamma Radioactivity Detection Limits and Associated Radionuclide Intakes Study in Artificial Human Urine Using Sodium-iodide and High-purity Germanium Detectors.

The performance of several gamma detectors was investigated for emergency urine bioassay screening of two radionuclides of concern: 131 I and 137 Cs. Unspiked artificial urine samples were measured for 10 min each on four different gamma detectors: 80% relative efficiency high-purity Ge detector in standard shielding, 102% low-background high-purity Ge detector equipped with top muon shield, 78% high-purity Ge well detector in standard shielding, and 4″ × 4″ NaI well detector in standard shielding. The measured gamma spectra were analyzed in two ways: (1) for the 364-keV peak region of 131 I and 662-keV peak region of 137 Cs and (2) for the total counts in the full energy spectrum (50-2,048 keV).

Investigation of factors influencing the implementation of two shared decision-making interventions in contraceptive care: a qualitative interview study among clinical and administrative staff.

Background: There is limited evidence on how to implement shared decision-making (SDM) interventions in routine practice. We conducted a qualitative study, embedded within a 2 × 2 factorial cluster randomized controlled trial, to assess the acceptability and feasibility of two interventions for facilitating SDM about contraceptive methods in primary care and family planning clinics. The two SDM interventions comprised a patient-targeted intervention (video and prompt card) and a provider-targeted intervention (encounter decision aids and training).

Enzymatic hydrolysis of steam exploded corncob residues after pretreatment in a twin-screw extruder.

A modified twin-screw extruder incorporated with a filtration device was used as a liquid/solid separator for xylose removal from steam exploded corncobs. A face centered central composite design was used to study the combined effects of various enzymatic hydrolysis process variables (enzyme loading, surfactant addition, and hydrolysis time) with two differently extruded corncobs (7% xylose removal, 80% xylose removal) on glucose conversion. The results showed that the extrusion process led to an increase in cellulose crystallinity, while structural changes could also be observed via SEM.

Application of low-background gamma-ray spectrometry to monitor radioactivity in the environment and food.

The results are described of an upgrade of the low-background gamma-ray spectrometry laboratory at New York State Department of Health by acquiring sensitivity to low-energy gamma rays. Tuning of the spectrometer and its low-energy response characteristics are described. The spectrometer has been applied to monitor the environment by measuring aerosols and water in New York State contaminated by the 2011 Fukushima accident plume.

Chromosome aberrations in vitro related to cytotoxicity of nonmutagenic chemicals and metabolic poisons.

Chromosome aberrations can occur by secondary mechanism(s) associated with cytotoxicity, induced by chemicals that do not attack DNA. Aberrations are formed from DNA double-strand breaks, and DSBs are known to be induced by nonmutagenic (Ames test negative) noncarcinogens at toxic levels [Storer et al. (1996): Mutat Res 368:59-101].

Fewer chromosome aberrations and earlier apoptosis induced by DNA synthesis inhibitors, a topoisomerase II inhibitor or alkylating agents in human cells with normal compared with mutant p53.

The human lymphoblastoid cell lines TK6 (normal p53) and WI-L2-NS or WTK1 (mutant p53) differ in sensitivity to killing and induction of gene mutations and chromosome aberrations by ionizing radiation. This may be related to decreased apoptosis in the cells with mutated p53, such that more damaged cells survive. We compared the response of the two cell types to various chemicals.

A role for mismatch repair in production of chromosome aberrations by methylating agents in human cells.

We have shown previously that certain alkylation products, or alkylation derived lesions, which induce chromosome aberrations (abs) persist for at least two cell cycles in Chinese hamster ovary cells. The increase in abs in the second cycle after treatment contrasts with the classical observation of reduction in ab yield with successive mitoses following ionizing radiation. Here we present evidence that processing of lesions by mismatch repair is a mechanism for ab induction by methylating agents.

Chromosome aberrations: persistence of alkylation damage and modulation by O6-alkylguanine-DNA alkyltransferase.

Alkylating agents produce a spectrum of DNA lesions alkylated at different sites on the molecule. These lesions differ in their propensities to cause effects such as cytotoxicity, mutations and sister-chromatid exchanges. We have used our observations that some methylating agents produce increasing levels of chromosome aberrations (abs) through successive cell cycles in Chinese hamster ovary cells, but not in normal human cells, to begin a study of which alkylated products are most likely to lead to chromosome abs, and in particular which adducts persist in DNA and cause abs after the first cell cycle.

Skin fibroblasts from aged Fischer 344 rats undergo similar changes in replicative life span but not immortalization with caloric restriction of donors.

We have compared the in vitro replicative life span and characteristics of immortalization of skin fibroblast cultures derived from ad libitum-fed and caloric-restricted Fischer 344 rats of 6, 24, and 29 months of age. Cells from all 6-, 24-, and 29-month-old animals showed a gradual decline in proliferative potential as evidenced by decreases in harvest density, in the fraction of cells initiating DNA synthesis, and in the number of population doublings per passage. These declines were accompanied by morphological changes including cell enlargement.

Karyotypic and phenotypic changes during in vitro aging of human endothelial cells.

Karyotypic and phenotypic changes were found in human adult endothelial cells (EC) during aging in vitro. A trisomy of chromosome 11 was found in 11 out of 12 EC cultures examined, derived from 9 cell lines from 8 donors. The incidence of this trisomy in some cell lines increased over time from 0% to as much as 100% near the end of their in vitro life span.

Selection of low frequency tumor cells from cell culture by growth in nude mice.

Tissue cultures of tumor cells are frequently utilized to characterize chromosomal changes when direct cytogenetic preparations on tumors fail. The present study demonstrates that chromosomal markers found in direct tumor preparations can become undetectable in cell culture at variable rates presumably because of overgrowth of normal cell components in the culture. Injection of cultured tumor cells into nude mice followed by direct chromosomal preparations on the resulting nude mouse tumors can be used to select cells with the original tumor karyotype.

Chromosomal abnormalities and gene amplification in renal cancers induced in rats by nickel subsulfide.

Nickel subsulfide (alpha Ni3S2) was administered to male Fischer-344 rats by unilateral intrarenal (i.r.) injection (20 mg per rat) to establish the time-course of alpha Ni3S2-induced erythrocytosis and to identify chromosomal abnormalities and molecular genetic aberrations in ensuing renal cancers.

Paradoxical changes in SCE frequencies persistently elevated in vivo, on exposure to a mutagen in vitro.

Lymphocyte cultures from 4 individuals with persistently significantly elevated frequencies of sister-chromatid exchange (SCE) were examined with no treatment, and with 2 concentrations of mitomycin C. In each of the 4 cases, the mean level of SCEs in the untreated lymphocytes exhibited a paradoxical reduction in SCE frequency when exposed to the lower (0.005 microgram/ml) of the two doses of mitomycin C.

Cytogenetic evaluation of human endothelial cell cultures.

Cytogenetic evaluation of serially subcultivated human endothelial cells revealed significant differences between cultures derived from fetal umbilical cords and cultures derived from various vessel sites in adults. A rapid increase in the prevalence of polyploid cells, to levels of 100% in many cases, was detected in human umbilical vein endothelial cell cultures but not in endothelial cell cultures from adult vessels. Because the development of polyploidy has been viewed as one signpost of in vitro senescence, it may be that these in vitro observations of high levels of polyploidy are a reflection of the fact that umbilical tissue is at the end of its in vivo developmental lifespan when studied.

Cytogenetic changes induced in human diploid fibroblasts by tsA58 SV40 at permissive and restrictive temperatures.

Human diploid fibroblasts have been transformed by ts A58 SV40. At the permissive temperature, apparent chromosome and chromatic rearrangements were observed in a high percentage of cells and the frequency of SCE increased. If the transformed phenotype returned to normal at the restrictive temperature these alterations also returned to normal levels.

Induction of sister chromatid exchanges by transformation with simian virus 40.

The frequency of sister chromatid exchange (SCE) has been followed sequentially after the addition of SV40 to human diploid fibroblast cultures. The SCE frequency was nearly the same in uninfected controls and in infected cultures before they became tumor antigen positive. When cells exhibited tumor antigen, the SCE frequency increased over a wide range, and changes in chromosome number and structure were observed simultaneously.