Ga Ion-Enhanced and Particle Shape-Dependent Generation of Reactive Oxygen Species in X-ray-Irradiated Composites.

The reported results test the effects of the collective behavior hypothesized to contribute to the production of more reactive oxygen species (ROS) in vitro and result in an enhanced radiosensitization. The role of particle shape in composites with gallium oxyhydroxide (GaOOH) particles and Matrigel is studied. Particles of two different shapes are embedded into the gel to understand only the materials effect on the generation of ROS rather than cell penetrating variations. The paper reports materials characterization by scanning electron microscopy and X-ray diffraction. The stability of the particles within the composite is assessed by quantification of leached metal using inductively coupled plasma mass spectrometry. The amount of ROS in each construct under variable radiation conditions is quantified in the presence and absence of PC12 cells seeded on top of the composites. The viability of cells is also recorded under different in vitro conditions. The collective materials characterization and the results from the bioassays are used to explain the role of anisotropy on the radiosensitization of nanostructures containing Ga. The presence of Ga ions in composites can have a radiosensitizing effect, and the amount of the available Ga3+ determines the magnitude of the radiosensitization. The shape of the particles determines the stability in aqueous solutions and release of Ga3+ that triggers ROS production. The concentration and shape of Ga-containing materials can be combined to generate an additive effect by increasing the amount of available free metal ions in solution. The studies with GaOOH containing composites enable one to explore the role of key parameters that lead to an increased efficiency of radiation treatments.

Population substructure in continuous and fragmented stands of Populus trichocarpa.

Population substructure has important implications for both basic and applied genetic research. We used 10 microsatellite markers to characterize population substructure in two ecologically and demographically contrasting populations of the model tree Populus trichocarpa. The Marchel site was a continuous stand growing in a mesic habitat in western Oregon, whereas the Vinson site consisted of three disjunct and isolated stands in the high desert of eastern Oregon. A previous study revealed that pollen-mediated gene flow is extensive in both populations. Surprisingly, model-based clustering, principal components analysis and analyses of molecular variance provided overwhelming support for the existence of at least two intermingled sub-populations within the continuous Marchel population (F(ST)=0.026, P<0.001), which occupied an area with a radius of only about 250 m. Genets in these two sub-populations appeared to have different relative clone ages and phenologies, leading us to hypothesize that they correspond to different seedling cohorts, each established from seeds produced by relatively few mothers. As expected, substructure was stronger in the fragmented Vinson population (F(ST)=0.071, P=0.001), and this difference appeared to result from the more extensive family structure in this population. Using group-likelihood methods, we reconstructed multiple interconnected half-sib families in the Vinson population, with some genets having as many as eight putative siblings. Researchers involved in ongoing and future association studies in P. trichocarpa should account for the likely presence of subtle but practically significant substructure in populations throughout the range of this species.

Extensive pollen flow in two ecologically contrasting populations of Populus trichocarpa.

Pollen-mediated gene flow was measured in two populations of black cottonwood using direct (paternity analysis) and indirect (correlated paternity) methods. The Marchel site was an area with an approximate radius of 250 m in a large continuous stand growing in a mesic habitat in western Oregon. In contrast, the Vinson site was an area with a radius of approximately 10 km and consisted of small, disjunct and isolated stands in the high desert of eastern Oregon. Pollen immigration was extensive in both populations, and was higher in the Marchel site (0.54 +/- 0.02) than in the substantially larger and more isolated Vinson site (0.32 +/- 0.02). Pollen pool differentiation among mothers was approximately five times stronger in the Vinson population (Phi FT = 0.253, N = 27 mothers) than in the Marchel population (Phi FT = 0.052, N = 5 mothers). Pollen dispersal was modelled using a mixed dispersal curve that incorporated pollen immigration. Predicted pollination frequencies generated based on this curve were substantially more accurate than those based on the widely used exponential power dispersal curve. Male neighbourhood sizes (sensu Wright 1946) estimated using paternity analysis and pollen pool differentiation were remarkably similar. They were three to five times smaller in the Vinson population, which reflected the substantial ecological and demographic differences between the two populations. When the same mathematical function was used, applying direct and indirect methods resulted in similar pollen dispersal curves, thus confirming the value of indirect methods as a viable lower-cost alternative to paternity analysis.

Using genetic markers to directly estimate gene flow and reproductive success parameters in plants on the basis of naturally regenerated seedlings.

Estimating seed and pollen gene flow in plants on the basis of samples of naturally regenerated seedlings can provide much needed information about "realized gene flow," but seems to be one of the greatest challenges in plant population biology. Traditional parentage methods, because of their inability to discriminate between male and female parentage of seedlings, unless supported by uniparentally inherited markers, are not capable of precisely describing seed and pollen aspects of gene flow realized in seedlings. Here, we describe a maximum-likelihood method for modeling female and male parentage in a local plant population on the basis of genotypic data from naturally established seedlings and when the location and genotypes of all potential parents within the population are known. The method models female and male reproductive success of individuals as a function of factors likely to influence reproductive success (e.g., distance of seed dispersal, distance between mates, and relative fecundity--i.e., female and male selection gradients). The method is designed to account for levels of seed and pollen gene flow into the local population from unsampled adults; therefore, it is well suited to isolated, but also wide-spread natural populations, where extensive seed and pollen dispersal complicates traditional parentage analyses. Computer simulations were performed to evaluate the utility and robustness of the model and estimation procedure and to assess how the exclusion power of genetic markers (isozymes or microsatellites) affects the accuracy of the parameter estimation. In addition, the method was applied to genotypic data collected in Scots pine (isozymes) and oak (microsatellites) populations to obtain preliminary estimates of long-distance seed and pollen gene flow and the patterns of local seed and pollen dispersal in these species.

Estimating pollen flow using SSR markers and paternity exclusion: accounting for mistyping.

Highly informative genetic markers, such as simple sequence repeats (SSRs), can be used to directly measure pollen flow by parentage analysis. However, mistyping (i.e. false inference of genotypes caused by the occurrence of null alleles, mutations, and detection errors) can lead to substantial biases in the estimates obtained. Using computer simulations, we evaluated a direct method for estimating pollen immigration using SSR markers and a paternity exclusion approach. This method accounts for mistyping and does not rely on assumptions about the distribution of male reproductive success. If ignored, even minor rates of mistyping (1.5%) resulted in overestimating pollen immigration by up to 150%. When we required at least two mismatching loci before excluding candidate fathers from paternity, the resulting pollen immigration estimates had small biases for rates of mistyping up to 4.5%. Requiring at least three mismatches for exclusion was needed to minimize the upward biases of pollen immigration caused by rates of mistyping up to 10.5%. The minimum number of highly variable SSR loci needed to minimize cryptic gene flow and obtain reliable estimates of pollen immigration varied from five to seven for a sampling scheme applicable to most conifers (i.e. when paternal haplotypes can be unambiguously determined). Between five and nine highly variable SSR loci were needed for a more general sampling scheme that is applicable to all diploid seed plants. With moderately variable SSR markers, consistently accurate estimates of pollen immigration could be obtained only for rates of mistyping up to 4.5%. We developed the POLLEN FLOW (PFL) computer program which can be used to obtain unbiased and precise estimates of pollen immigration under a wide range of conditions, including population sizes as large as 600 parents and mistyping rates as high as 10.5%.

Highly variable SSR markers in Douglas-fir: Mendelian inheritance and map locations.

Twenty-two highly variable SSR markers were developed in Douglas-fir [ Pseudotsuga menziesii (Mirb.) Franco] from five SSR-enriched genomic libraries. Fifteen PCR primer pairs amplified a single codominant locus, while seven primer pairs occasionally amplified two loci. The Mendelian inheritance of all 22 SSRs was confirmed via segregation analyses in several Douglas-fir families. The mean observed heterozygosity and the mean number of alleles per locus were 0.855 (SE=0.020) and 23 (SE=1.6), respectively. Twenty markers were used in genetic linkage analysis and mapped to ten known linkage groups. Because of their high polymorphism and unambiguous phenotypes, 15 single-locus markers were selected as the most suitable for DNA fingerprinting and parentage analysis. Only three SSRs were sufficient to achieve an average probability of exclusion from paternity of 0.998 in a Douglas-fir seed orchard block consisting of 59 parents.

Complex patterns of mating revealed in a Eucalyptus regnans seed orchard using allozyme markers and the neighbourhood model.

The neighbourhood model apportions offspring of individual mother plants to self-fertilization, outcrossing to males within a circumscribed area around the mother plant (the neighbourhood), and outcrossing to males outside the neighbourhood. Formerly the model was applied only to haploid pollen gametes in the offspring of conifers, but is extended so that it can be used with genotypic data from diploid offspring of both angiosperms and gymnosperms. In addition, it is shown that the mating parameters can be estimated without independent estimates of allele frequencies in the pollen pools outside the neighbourhood; thus the model might be applied effectively to natural populations exposed to unknown external pollen sources. Parameters of the neighbourhood mating model were estimated for a 10-year-old seed orchard population of the insect-pollinated tree, Eucalyptus regnans, in southeast Australia, which contained a mixture of two geographical provenances (Victoria and Tasmania). The mating patterns revealed were complex. Crosses between trees of the same provenance occurred three times more often than crosses between trees of different provenances. Levels of self-fertilization and patterns of mating within neighbourhoods were influenced by provenance origin, crop fecundity and orchard position (central vs. edge) of mother trees. Gene dispersal, however, was extensive, with approximately 50% of effective pollen gametes coming from males more than 40 m away from mother trees (average distance between neighbouring trees was 7.4 m). Thus, insect pollinators are efficient promoters of cross-fertilization in this orchard, with the result that the effective number of males mating with each female is large.

Automated charge processing streamlines data entry.

A healthcare organization can significantly improve its billing office's performance by implementing an automated charge-processing system that integrates scanning technology with hospital and physician office billing systems. Such a system offers large healthcare organizations a means to eliminate costly and inefficient manual processing of paper charge sheets, thereby improving productivity and accuracy. An automated charge-processing system allows a billing department to automatically post, track, monitor, control, and reconcile all charges through a central database. To implement the system, a healthcare organization should assemble a project team composed of representatives from information services, the software supplier, and the organization's business offices. The team will be responsible for setting up the system; designing an easily scannable, standard charge form; establishing the rules the system will follow for posting charges; and designing billing office reports.

Computer imaging and workflow systems in the business office.

Computer imaging and workflow technology automates many business processes that currently are performed using paper processes. Documents are scanned into the imaging system and placed in electronic patient account folders. Authorized users throughout the organization, including preadmission, verification, admission, billing, cash posting, customer service, and financial counseling staff, have online access to the information they need when they need it. Such streamlining of business functions can increase collections and customer satisfaction while reducing labor, supply, and storage costs. Because the costs of a comprehensive computer imaging and workflow system can be considerable, healthcare organizations should consider implementing parts of such systems that can be cost-justified or include implementation as part of a larger strategic technology initiative.

Using artificial intelligence to automate remittance processing.

The consolidated business office of the Allegheny Health Education Research Foundation (AHERF), a large integrated healthcare system based in Pittsburgh, Pennsylvania, sought to improve its cash-related business office activities by implementing an automated remittance processing system that uses artificial intelligence. The goal was to create a completely automated system whereby all monies it processed would be tracked, automatically posted, analyzed, monitored, controlled, and reconciled through a central database. Using a phased approach, the automated payment system has become the central repository for all of the remittances for seven of the hospitals in the AHERF system and has allowed for the complete integration of these hospitals' existing billing systems, document imaging system, and intranet, as well as the new automated payment posting, and electronic cash tracking and reconciling systems. For such new technology, which is designed to bring about major change, factors contributing to the project's success were adequate planning, clearly articulated objectives, marketing, end-user acceptance, and post-implementation plan revision.

Adaptive significance of intermittent shoot growth in Douglas-fir seedlings.

We tested the hypothesis that intermittent (lammas) shoot growth in Douglas-fir (Pseudotsuga menziesii var menziesii (Mirb.) Franco) seedlings from dry regions of southwest Oregon is adaptively significant. Seedlings from open-pollinated families (160 total) from two inland (dry) and two coastal (wet) sources were grown under either well-watered or intermittent drought conditions (temporary drought followed by rewatering) for two growing seasons. In the first growing season, the results supported the hypothesis: the frequency of a second flush was genetically controlled (although weakly, h(f) (2)

Computer program for the analysis of mutational spectra: application to p53 mutations.

Mutations in the p53 oncogene are extremely common in human cancers, and environmental exposure to mutagenic agents may play a role in the frequency and nature of the mutations. Differences in the patterns of p53 mutations have been observed for different tumor types. It is not trivial to determine if the differences observed in two mutational spectra are statistically significant. To this end, we present a computer program for comparison of two mutational spectra. The program runs on IBM-compatible personal computers and is freely available. The input for the program is a text file containing the number and nature of mutations observed in the two spectra. The output of the program is a P value, which indicates the probability that the two spectra are drawn from the same population. To demonstrate the program, the mutational spectra of single base substitutions in the p53 gene are compared in (i) bladder cancers from smokers and non-smokers, (ii) small-cell lung cancers, non-small-cell lung cancers and colon cancers and (iii) hepatocellular carcinomas from high- and low-aflatoxin exposure groups. p53 mutations differ in several important aspects from a typical mutational spectra experiment, where a homogeneous population of cells is treated with a specific mutagen and mutations at a specific locus are recovered by phenotypic selection. The means by which p53 mutations are recognized is by the appearance of a cancer, and this phenotype is very complex and varied.

Using paternity analysis to measure effective pollen dispersal in plant populations.

Paternity analysis can be used to estimate mean effective pollen dispersal (micro(d)) by sampling offspring from a mother plant and assaying each for a large number of allozyme loci. The male in the population with the highest likelihood of paternity, based entirely on the degree of genetic relationship with the offspring (transition probability) or combined with information on probability of mating with the mother plant, is inferred as the pollen parent. Computer simulations show that the mean distance between inferred males and mother plants (d) reliably estimates micro(d) in defined circumstances. If male mating success decreases with distance from the mother plant, paternity inference based entirely on transition probabilities results in d values that are upwardly biased, perhaps considerably. More reliable estimates can be obtained in this situation when prior information on the general form of the relationship between mating success and distance between mates (the distance function) is used, along with transition probabilities, to infer paternity. However, this procedure is valid only when the general form of the distance function can be reliably assumed. Computer simulations also show that the bootstrap method can be used to closely approximate the SE of .

Relative family performance and variance structure of open-pollinated Douglas-fir seedlings grown in three competitive environments.

Open-pollinated Douglas-fir (Pseudotsuga menziesii var 'menziesii' (Mirb.) Franco) families were tested in three contrasting competitive environments to test the hypothesis that relative performance as measured by total seedling dry weight is dependent upon distance or genotype of neighbors. The three competitive environmnts included (1) a mixture of individuals from all families planted at close spacing, (2) single (pure) family blocks planted at close spacing, and (3) individuals from all families planted at a wide, non-competitive spacing. Despite occasional large changes in rank between competitive environments and only moderate correlations of family means between competitive environments, the family x competitive environment interaction was non-significant. Furthermore, families did not differ significantly in competitive ability or density tolerance. The competitive environment in which seedlings were grown, however, had a large effect on estimates of variance components, which in turn led to large differences in estimates of heritability and genetic gain. Evaluation of families in mixture resulted in the largest estimates of heritability, while evaluation in pure family blocks resulted in the lowest. Analysis of correlated response to selection indicated that testing and selection in mixture result in the largest estimated gain, even if progeny of selected individuals are subsequently grown in a pure or non-competitive environment.

Statistical test for the comparison of samples from mutational spectra.

The Monte Carlo estimate of the p value of the hypergeometric test is described and advocated for the testing of the hypothesis that different treatments induce the same mutational spectrum. The hypergeometric test is a generalization of Fisher's "exact" test for tables with more than two rows and two columns. Use of the test is demonstrated by the analysis of data from the characterization of nonsense mutations in the lacI gene of Escherichia coli. Unlike the chi-square test, the hypergeometric test remains valid when applied to sparse cross-classification tables. The hypergeometric test has the most discrimination power of any statistical test that could be employed routinely to compare samples from mutational spectra. Direct application of the hypergeometric test to large cross-classification tables is excessively computation intensive, but estimation of its p value via Monte Carlo techniques is practical.

Reproduction in Fischer-344 rats exposed to methyl chloride by inhalation for two generations.

Male and female Fischer-344 rats were exposed to methyl chloride by inhalation (0, 150, 475, or 1500 ppm, 6 hr/day, 5 days/week, 40 males and 80 females per group). The only treatment-related clinical signs were a 10 to 20% body weight gain depression (BWGD) in both males and females exposed to 1500 ppm at all weekly weighings after 2 weeks of exposure and a 5-7% BWGD in 475-ppm exposed animals after Day 57. After 10 weeks the exposure schedule was changed to 6 hr/day, 7 days/week and each male was mated to two exposed females. The mating period was ended after 2 weeks, at which point 10 males/group were necropsied. The only treatment-related lesions found were severe bilateral testicular degeneration (10/10) and granulomas in the epididymis (3/10) in the 1500-ppm males. The remaining 30 males per group were then removed from exposure and mated during a 2-week period with 60 unexposed females. The exposed females were continued on exposure from the start of mating to Postnatal Day 28 (6 hr/day, 7 days/week). The females were not exposed from Gestation Day 18 to Postnatal Day 4, and the pups were never directly exposed prior to weaning. There were no significant differences between groups in the number of exposed or unexposed females that mated, as evidenced by copulation plugs. No litters were born to exposed or unexposed females mated to the 1500-ppm males. There was no significant difference in the number of litters produced by the 150-ppm groups when compared to the control groups. Fewer litters were born in the 475-ppm groups than in the control groups. No differences in litter size, sex ratio, pup viability, or pup growth were found among the 475-ppm, 150-ppm, or control F0 groups. When bred 10 weeks after the cessation of exposures, 5 to 20 1500-ppm F0 males had regained the ability to sire normal litters. The same number of 475-ppm F0 males proved as fertile (15/20) as control F0 males (13/20). After weaning, F1 pups from the 475-, 150-, and 0-ppm groups were exposed to the same concentrations of methyl chloride for 10 weeks and then mated. A trend toward decreased fertility was found in the 475-ppm F1 group.

The mating system in natural and shelterwood stands of Douglas-fir.

Mating systems in two pairs of old-growth uncut and adjacent shelterwood stands of Douglas-fir (Pseudotsuga menziesii var. 'menziesii') were compared by estimating the proportions of viable progenies due to outcrossing (t) with both single-locus and multilocus techniques. Single-locus population estimates (ts), ranging from 0.41 to 1.16, were significantly (P<0.05) heterogeneous among loci in three of four stands; mean single-locus estimates for shelterwoods were not significantly different from those for uncut stands. Multilocus population estimates (tm) ranged from 0.94 to 1.00; again, estimates for shelterwoods were not significantly different from those for uncut stands. Multilocus estimates were slightly higher than mean single-locus estimates for uncut stands but were nearly equivalent for shelterwoods, suggesting that related matings other than selfs may be associated with uncut stands, but not shelterwoods. Individual-tree outcrossing rates (tm i), estimated for six trees in each shelterwood, ranged from 0.90 to 1.10 and were significantly heterogeneous among trees at one of the two shelterwoods. Outcrossing was high (> 0.90) in both uncult and shelterwood stands, and no evidence indicated that low parent-tree density had affected stand outcrossing rates.

Estimation of gene flow into two seed orchards of loblolly pine (Pinus taeda L.).

Multilocus allozyme markers, which were present in background stands but not in two seed orchards, enabled estimation of gene flow into two seed orchards of loblolly pine. Estimates averaged 36% in two orchards over three years. When pollen pool frequencies in the background stands were used rather than gene frequencies in the non-orchard trees, the estimates averaged 60%. In one year, trees in the row on the edge of one orchard received significantly more pollen from background stands. Estimates of gene flow between the two 2-ha orchards average 10%. Implications of the observed levels of gene flow are discussed in terms of population genetics and seed orchard management.