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Hart CL, Batty GD, Morrison DS, Mitchell RJ, Smith GD. Obesity, overweight and liver disease in the Midspan prospective cohort studies. Int J Obes (Lond) 2010; 34:1051-9. [PMID: 20142829 PMCID: PMC2887083 DOI: 10.1038/ijo.2010.20] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
OBJECTIVES To analyse the relationship between body mass index (BMI) and liver disease in men and women. DESIGN The Midspan prospective cohort studies. PARTICIPANTS The three studies were: Main study, screened in 1965-1968, workplaces across Scotland, the general population of the island of Tiree and mainland relatives; Collaborative study, conducted from 1970 to 1973, 27 workplaces in Glasgow, Clydebank and Grangemouth; Renfrew/Paisley general population study, screened in 1972-1976. After exclusions there were 16 522 men and 10 216 women, grouped by BMI into under/normal weight (< 25 kg m(-2)), overweight (25 to < 30 kg m(-2)) and obese (>or=30 kg m(-2)). MEASUREMENTS Relative rates (RRs) of liver disease mortality, subdivided into liver cancer and all other liver disease, by BMI category and per s.d. increase in BMI, followed-up to end 2007. RRs of liver disease from any diagnosis on the death certificate, hospital discharge records or cancer registrations (Collaborative and Renfrew/Paisley studies only 13 027 men and 9328 women). Analyses adjusted for age and study, then other confounders. RESULTS In total, 146 men (0.9%) and 61 women (0.6%) died of liver disease as main cause. There were strong associations of BMI with liver disease mortality in men (RR per s.d. increase in BMI=1.41 (95% confidence interval 1.21-1.65)). Obese men had more than three times the rate of liver disease mortality than under/normal weight men. Adjustment for other risk factors had very little effect. No substantial or robust associations were observed in women. In all, 325 men (2.5%) and 155 women (1.7%) had liver disease established from any source. Similar positive associations were observed for men, and there was evidence of a relationship in women. CONCLUSIONS BMI is related to liver disease, although not to liver disease mortality in women. The current rise in overweight and obesity may lead to a continuing epidemic of liver disease.
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Walker DK, Bowers SJ, Mitchell RJ, Potchoiba MJ, Schroeder CM, Small HF. Preclinical assessment of the distribution of maraviroc to potential human immunodeficiency virus (HIV) sanctuary sites in the central nervous system (CNS) and gut-associated lymphoid tissue (GALT). Xenobiotica 2008; 38:1330-9. [DOI: 10.1080/00498250802447409] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Leith ID, Mitchell RJ, Truscott AM, Cape JN, van Dijk N, Smith RI, Fowler D, Sutton MA. The influence of nitrogen in stemflow and precipitation on epiphytic bryophytes, Isothecium myosuroides Brid., Dicranum scoparium Hewd. and Thuidium tamariscinum (Hewd.) Schimp of Atlantic oakwoods. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2008; 155:237-246. [PMID: 18343004 DOI: 10.1016/j.envpol.2007.11.031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2007] [Revised: 11/23/2007] [Accepted: 11/26/2007] [Indexed: 05/26/2023]
Abstract
The spatial relationship between the concentration and deposition of the major ions in precipitation and stemflow and their influence on the tissue nitrogen concentration of three epiphytic bryophytes on Quercus petraea (Matt) Liebl. and Q. robur L. was investigated at seven UK Atlantic oak woodland sites with a range of total N deposition of 55-250 mmol m(-2). The main driver of change in tissue N concentrations of three epiphytic bryophytes (Isothecium myosuroides Brid. (Eurhynchium myosuroides (Brid.) Schp.), Dicranum scoparium Hewd. and Thuidium tamariscinum (Hewd.) Schimp.) was total N deposition in stemflow, dominated by ammonium deposition. The three epiphytic species also showed strong relationships between tissue N concentration and total N deposition in rainfall but a poor correlation with total N ion concentration in rainfall. This study shows that epiphytic bryophytes utilise stemflow N and thus increase their risk from inputs of total N deposition compared to terricolous species at the same site.
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Ding J, Patton N, Deary IJ, Strachan MWJ, Fowkes FGR, Mitchell RJ, Price JF. Retinal microvascular abnormalities and cognitive dysfunction: a systematic review. Br J Ophthalmol 2008; 92:1017-25. [DOI: 10.1136/bjo.2008.141994] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Mitchell RJ, Ferguson RK, Macdonald A, Dunlop MG, Campbell H, Porteous ME. Cascade genetic testing for mismatch repair gene mutations. Fam Cancer 2008; 7:293-301. [PMID: 18389387 DOI: 10.1007/s10689-008-9192-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2007] [Accepted: 03/21/2008] [Indexed: 11/29/2022]
Abstract
Mismatch repair gene mutation carriers have a high risk of developing colorectal cancer, and can benefit from appropriate surveillance. A combined population based ascertainment cascade genetic testing approach provides a systematic and potentially effective strategy for identifying such carriers. We have developed a Markov Chain computer model system which simulates various factors influencing cascade genetic testing; including demographics, uptake, genetic epidemiology and family size. This was used to evaluate cascade genetic testing for mismatch repair gene mutations in theory and practice. Simulations focussed on the population of Scotland by way of illustration, and were based on a 20-year programme in which index cases were ascertained from colorectal cancer cases aged<55 years at onset. Results indicated that without practical barriers to cascade genetic testing, 545 (95% CI=522, 568) carriers could be identified; 42% of the population total. This comprised approximately 140 index cases, 302 asymptomatic relatives and 104 previously affected relatives. However, when realistic ascertainment and acceptance rates were used to inform simulations, only 257 (95% CI=246, 268) carriers, about 20% of the carrier population, were identifiable. Of these approximately 112 were index cases, 108 were asymptomatic relatives, and 37 were previously affected relatives. This contrast emphasises the importance of ascertainment and acceptance rates. Likewise the low number of index cases shows that case identification is a limiting factor. In the absence of robust data from epidemiological studies, these findings can inform decisions about the use of cascade genetic testing for mismatch repair gene mutations.
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Ballantyne KN, van Oorschot RAH, Mitchell RJ. Locked nucleic acids in PCR primers increase sensitivity and performance. Genomics 2008; 91:301-5. [PMID: 18164179 DOI: 10.1016/j.ygeno.2007.10.016] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2007] [Revised: 10/21/2007] [Accepted: 10/29/2007] [Indexed: 11/30/2022]
Abstract
The incorporation of locked nucleic acids (LNAs) into oligonucleotide primers has been shown to increase template binding strength and specificity for DNA amplification. Real-time PCR and DNA sequencing have been shown to be significantly enhanced by the use of LNAs. Theoretically, increasing primers' binding strength may also increase the sensitivity of conventional PCR, reducing minimum template requirements. We compared LNA-modified PCR primers with their standard DNA counterparts for amplification sensitivity with template amounts as low as 5 pg. Although the results are highly dependent on the design of the LNA primers, large increases in peak height can be achieved from as little as 75 pg, as well as clearer and more complete profiles. Increased amplification success with lower template amounts may also be seen. Additionally, the use of LNAs can enhance multiplexing. Thus, incorporating LNAs into PCR primers can increase amplification success, sensitivity, and performance under a wide range of conditions.
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Mitchell RJ, Kreskas M, Baxter E, Buffalino L, Van Oorschot RAH. An investigation of sequence deletions of amelogenin (AMELY), a Y-chromosome locus commonly used for gender determination. Ann Hum Biol 2006; 33:227-40. [PMID: 16684695 DOI: 10.1080/03014460600594620] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
BACKGROUND Accurate gender determination is crucial in many scientific disciplines, but especially so in prenatal diagnosis of X-linked diseases and forensic investigations. Today, molecular techniques, especially typing for a length variation in the X-Y homologous amelogenin gene (AMELX and AMELY), are used for gender assignation. This amelogenin test is an integral part of most PCR multiplex kits that are used for DNA profiling, but in 1998 there was a report of two normal males being typed as female with this test. Subsequently, a small number of amelogenin negative (or AMELY null) males have been reported in various populations but little data are available characterising these deletions. AIMS The study aims to determine the size of the deletion in five AMELY null males by typing DNA samples for markers surrounding this gender-determining locus. The possible relationships among the AMELY null samples are examined through analysis of their deletion size and associated Y-chromosome microsatellite haplotypes. We also attempt to determine the frequency of AMELY negative males in Australia. SUBJECTS AND METHODS DNA samples from five AMELY null males, from different geographical regions, were made available for this study. The samples were typed for eight sites, all located on the short arm of the Y chromosome, using PCR and gel electrophoresis. Eleven Y-chromosome specific microsatellites were also typed on each sample in order to generate haplotypes for phylogenetic analysis. A questionnaire was sent to all Australian forensic centres requesting information on the frequency of AMELY negative males observed in their laboratories. RESULTS Two different sized deletions were seen in the five AMELY null samples. One deletion (in two samples) has a size of between 304 and 731 kbp, whereas the other (in three samples) ranges between 712 and 1001 kbp. Y-microsatellite haplotypes indicate that the smaller deletion is probably identical in the two samples, but this is not the case with the larger deletion. The frequency of AMELY negative is rare in Australia, with an overall frequency of 0.02%. CONCLUSION Comparisons of both deletion size and haplotypes with published data suggest that most AMELY nulls are the result of independent evolutionary events, even in those populations where the frequency is relatively high. Although AMELY null males are extremely rare in most populations, typing an additional gender-determining locus should be considered in forensic investigations where the reference sample is of unknown gender.
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Runion GB, Davis MA, Pritchard SG, Prior SA, Mitchell RJ, Torbert HA, Rogers HH, Dute RR. Effects of elevated atmospheric carbon dioxide on biomass and carbon accumulation in a model regenerating longleaf pine community. JOURNAL OF ENVIRONMENTAL QUALITY 2006; 35:1478-86. [PMID: 16825468 DOI: 10.2134/jeq2005.0164] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Plant species vary in response to atmospheric CO2 concentration due to differences in physiology, morphology, phenology, and symbiotic relationships. These differences make it very difficult to predict how plant communities will respond to elevated CO2. Such information is critical to furthering our understanding of community and ecosystem responses to global climate change. To determine how a simple plant community might respond to elevated CO2, a model regenerating longleaf pine community composed of five species was exposed to two CO2 regimes (ambient, 365 micromol mol(-1) and elevated, 720 micromol mol(-1)) for 3 yr. Total above- and belowground biomass was 70 and 49% greater, respectively, in CO2-enriched plots. Carbon (C) content followed a response pattern similar to biomass, resulting in a significant increase of 13.8 Mg C ha(-1) under elevated CO2. Responses of individual species, however, varied. Longleaf pine (Pinus palustris Mill.) was primarily responsible for the positive response to CO2 enrichment. Wiregrass (Aristida stricta Michx.), rattlebox (Crotalaria rotundifolia Walt. Ex Gmel.), and butterfly weed (Asclepias tuberosa L.) exhibited negative above- and belowground biomass responses to elevated CO2, while sand post oak (Quercus margaretta Ashe) did not differ significantly between CO2 treatments. As with pine, C content followed patterns similar to biomass. Elevated CO2 resulted in alterations in community structure. Longleaf pine comprised 88% of total biomass in CO2-enriched plots, but only 76% in ambient plots. In contrast, wiregrass, rattlebox, and butterfly weed comprised 19% in ambient CO2 plots, but only 8% under high CO2. Therefore, while longleaf pine may perform well in a high CO2 world, other members of this community may not compete as well, which could alter community function. Effects of elevated CO2 on plant communities are complex, dynamic, and difficult to predict, clearly demonstrating the need for more research in this important area of global change science.
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Addington RN, Donovan LA, Mitchell RJ, Vose JM, Pecot SD, Jack SB, Hacke UG, Sperry JS, Oren R. Adjustments in hydraulic architecture of Pinus palustris maintain similar stomatal conductance in xeric and mesic habitats. PLANT, CELL & ENVIRONMENT 2006; 29:535-45. [PMID: 17080605 DOI: 10.1111/j.1365-3040.2005.01430.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
We investigated relationships between whole-tree hydraulic architecture and stomatal conductance in Pinus palustris Mill. (longleaf pine) across habitats that differed in soil properties and habitat structure. Trees occupying a xeric habitat (characterized by sandy, well-drained soils, higher nitrogen availability and lower overstory tree density) were shorter in stature and had lower sapwood-to-leaf area ratio (A(S):A(L)) than trees in a mesic habitat. The soil-leaf water potential gradient (psiS - psiL) and leaf-specific hydraulic conductance (kL) were similar between sites, as was tissue-specific hydraulic conductivity (Ks) of roots. Leaf and canopy stomatal conductance (gs and Gs, respectively) were also similar between sites, and they tended to be somewhat higher at the xeric site during morning hours when vapour pressure deficit (D) was low. A hydraulic model incorporating tree height, A(S):A(L) and psiS-psiL accurately described the observed variation in individual tree G(Sref) (G(S) at D = 1 kPa) across sites and indicated that tree height was an important determinant of G(Sref) across sites. This, combined with a 42% higher root-to-leaf area ratio (A(R):A(L)) at the xeric site, suggests that xeric site trees are hydraulically well equipped to realize equal--and sometimes higher potential for conductance compared with trees on mesic sites. However, a slightly more sensitive stomatal closure response to increasing D observed in xeric site trees suggests that this potential for higher conductance may only be reached when D is low and when the capacity of the hydraulic system to supply water to foliage is not greatly challenged.
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Mitchell RJ, Campbell H, Farrington SM, Brewster DH, Porteous MEM, Dunlop MG. Prevalence of family history of colorectal cancer in the general population. Br J Surg 2005; 92:1161-4. [PMID: 15997443 DOI: 10.1002/bjs.5084] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
BACKGROUND Robust estimates of the prevalence of a family history of colorectal cancer in the general population are essential to inform planning of provision for colonoscopic surveillance and for clinical genetics services. However, there is a paucity of high-quality data. METHODS Computerized record linkage was used to assess systematically the family history of 160 cancer-free community subjects and thereby provide prevalence data that are independent of participant recall. The data set comprised 2664 first- and second-degree relatives of study subjects, with 148 068 years at risk. RESULTS Of people in the 30-70 years age range, 9.4 (95 per cent confidence interval (c.i.) 5.8 to 14.9) per cent had a first-degree relative affected by colorectal cancer, and 28.8 (95 per cent c.i. 22.3 to 36.2) per cent had an affected first- or second-degree relative. Between 0 and 3.1 per cent of study subjects merited colonic surveillance, depending on the stringency of the guidelines used. CONCLUSION An appreciable proportion of the general population has a relative affected by colorectal cancer, sufficient to merit screening under certain criteria. In the absence of good-quality evidence supporting colonoscopic surveillance in groups at moderate risk, these data directly inform the planning of services for people with a family history of colorectal cancer. However, the clinical risk and financial implications of screening should be taken into account.
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Mitchell RJ, Holden JJA, Zhang C, Curlis Y, Slater HR, Burgess T, Kirkby KC, Carmichael A, Heading KD, Loesch DZ. FMR1 alleles in Tasmania: a screening study of the special educational needs population. Clin Genet 2005; 67:38-46. [PMID: 15617547 DOI: 10.1111/j.1399-0004.2004.00344.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The distribution of fragile X mental retardation-1 (FMR1) allele categories, classified by the number of CGG repeats, in the population of Tasmania was investigated in 1253 males with special educational needs (SEN). The frequencies of these FMR1 categories were compared with those seen in controls as represented by 578 consecutive male births. The initial screening was based on polymerase chain reaction analysis of dried blood spots. Inconclusive results were verified by Southern analysis of a venous blood sample. The frequencies of common FMR1 alleles in both samples, and of grey zone alleles in the controls, were similar to those in other Caucasian populations. Consistent with earlier reports, we found some (although insignificant) increase of grey zone alleles in SEN subjects compared with controls. The frequencies of predisposing flanking haplotypes among grey zone males FMR1 alleles were similar to those seen in other Caucasian SEN samples. Contrary to expectation, given the normal frequency of grey zone alleles, no premutation (PM) or full mutation (FM) allele was detected in either sample, with only 15 fragile X families diagnosed through routine clinical admissions registered in Tasmania up to 2002. An explanation of this discrepancy could be that the C19th founders of Tasmania carried few PM or FM alleles. The eight to ten generations since white settlement of Tasmania has been insufficient time for susceptible grey zone alleles to evolve into the larger expansions.
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Shi XJ, Michaels HJ, Mitchell RJ. Effects of self-pollination and maternal resources on reproduction and offspring performance in the wild lupine, Lupinus perennis (Fabaceae). ACTA ACUST UNITED AC 2005. [DOI: 10.1007/s00497-005-0250-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Mitchell RJ, Gu MB. An Escherichia coli biosensor capable of detecting both genotoxic and oxidative damage. Appl Microbiol Biotechnol 2004; 64:46-52. [PMID: 12937953 DOI: 10.1007/s00253-003-1418-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2003] [Revised: 07/09/2003] [Accepted: 07/18/2003] [Indexed: 10/26/2022]
Abstract
A two-plasmid dual reporter Escherichia coli biosensor was developed using the genes for bacterial bioluminescence and a mutant of the green fluorescent protein, GFPuv4. To achieve this, the two plasmids, which were derivatives of pBR322 and pACYC184, had compatible origins of replication and different antibiotic selection markers: ampicillin and tetracycline. The parent strains DK1 and ACRG43, each carrying a single plasmid with one of the fusion genes (strain DK1 harboring a fusion of the katG promoter to the lux operon while in ACRG43, the recA promoter was fused with the GFP gene), were responsive to oxidative and DNA damage, respectively, resulting in higher bioluminescence or fluorescence under the relevant toxic conditions. The responses of the dual sensor strain, DUAL22, to various toxicants, e.g., mitomycin C, N-methyl-N-nitro--nitrosoguanidine, hydrogen peroxide and cadmium chloride, were characterized and compared with the responses of the parent strains to the same chemicals. Finally, several chemical mixtures that cause various stress responses were tested to demonstrate the ability of this biosensor to detect specific stress responses within a multiple toxicity environment.
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Mitchell RJ, Brewster D, Campbell H, Porteous MEM, Wyllie AH, Bird CC, Dunlop MG. Accuracy of reporting of family history of colorectal cancer. Gut 2004; 53:291-5. [PMID: 14724166 PMCID: PMC1774933 DOI: 10.1136/gut.2003.027896] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/30/2003] [Indexed: 12/18/2022]
Abstract
BACKGROUND AND AIMS Family history is used extensively to estimate the risk of colorectal cancer but there is considerable potential for recall bias and inaccuracy. Hence we systematically assessed the accuracy of family history reported at interview compared with actual cancer experience in relatives. METHODS Using face to face interviews, we recorded family history from 199 colorectal cancer cases and 133 community controls, totalling 5637 first and second degree relatives (FDRs/SDRs). We linked computerised cancer registry data to interview information to determine the accuracy of family history reporting. RESULTS Cases substantially underreported colorectal cancer arising both in FDRs (sensitivity 0.566 (95% confidence interval (CI) 0.433, 0.690); specificity 0.990 (95% CI 0.983, 0.994)) and SDRs (sensitivity 0.271 (95% CI 0.166, 0.410); specificity 0.996 (95% CI 0.992, 0.998)). There was no observable difference in accuracy of reporting family history between case and control interviewees. Control subjects similarly underreported colorectal cancer in FDRs (sensitivity 0.529 (95% CI 0.310, 0.738); specificity 0.995 (95% CI 0.989, 0.998)) and SDRs (sensitivity 0.333 (95% CI 0.192, 0.512); specificity 0.995 (95% CI 0.991, 0.995)). To determine practical implications of inaccurate family history, we applied family history criteria before and after record linkage. Only two of five families reported at interview to meet surveillance criteria did so after validation, whereas only two of six families that actually merited surveillance were identified by interview. CONCLUSIONS This study has quantified the inaccuracy of interview in identifying people at risk of colorectal cancer due to a family history. Colorectal cancer was substantially underreported and so family history information should be interpreted with caution. These findings have considerable relevance to identifying patients who merit surveillance colonoscopy and to epidemiological studies.
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Mitchell RJ, Karron JD, Holmquist KG, Bell JM. The influence of Mimulus ringens floral display size on pollinator visitation patterns. Funct Ecol 2004. [DOI: 10.1111/j.1365-2435.2004.00812.x] [Citation(s) in RCA: 170] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Huggins RM, Loesch DZ, Qian GQ, Bui QM, Mitchell RJ, Dobson M, Taylor AK. Hierarchical Bayes model for random haplotype and family effects in the transmission of fragile-X. Genet Epidemiol 2004; 26:294-304. [PMID: 15095389 DOI: 10.1002/gepi.10316] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A model for the transmission of the CGG repeat sequence associated with the fragile-X dynamic mutation in the FMR1 gene is developed. The model incorporates both haplotype and family effects on the expansion rate of the sequence. The resulting random effects model is fitted to new data, using computer-intensive Markov chain Monte Carlo methods. The results demonstrate both the FRAXAC1-DXS458 haplotype and family effects on the transmission of CGG repeats from mother to offspring.
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Karron JD, Mitchell RJ, Holmquist KG, Bell JM, Funk B. The influence of floral display size on selfing rates in Mimulus ringens. Heredity (Edinb) 2003; 92:242-8. [PMID: 14666135 DOI: 10.1038/sj.hdy.6800402] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Pollinators often visit several flowers in sequence on plants with large floral displays. This foraging pattern is expected to influence the rate of self-fertilization in self-compatible taxa. To quantify the effects of daily floral display on pollinator movements and selfing, we experimentally manipulated flower number in four replicate (cloned) arrays of Mimulus ringens (Scrophulariaceae), each consisting of genets with unique combinations of homozygous marker genotypes. Four display classes (two, four, eight and 16 flowers) were present in each array. Pollinator visitation rate per flower and seed set per fruit were unaffected by display. However, flower number strongly influenced the frequency of within-plant pollinator movements, which increased from 13.8% of probes on two-flower displays to 77.6% of probes on 16-flower displays. The proportion of within-plant movements was significantly correlated with selfing (r = 0.993). The increase from 22.9% selfing on two-flower displays to 37.3% selfing on 16-flower displays reflects changes in the extent of geitonogamous self-pollination. We estimate that approximately half of all selfing on 16-flower displays resulted from geitonogamy. Selfing also varied dramatically among fruits within display classes. Nested ANOVA indicates that differences among flowers on two-flower ramets accounted for 45.4% of the variation in selfing, differences among genets accounted for 16.1% of the variation, and statistical and sampling error accounted for 38.5% of the variation. Differences among flowers within ramets may reflect the order of sequential floral probes on a display.
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Hartley SE, Gardner SM, Mitchell RJ. Indirect effects of grazing and nutrient addition on the hemipteran community of heather moorlands. J Appl Ecol 2003. [DOI: 10.1046/j.1365-2664.2003.00846.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Driscoll TR, Mitchell RJ, Hendrie AL, Healey SH, Mandryk JA, Hull BP. Unintentional fatal injuries arising from unpaid work at home. Inj Prev 2003; 9:15-9. [PMID: 12642552 PMCID: PMC1730915 DOI: 10.1136/ip.9.1.15] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVE Unpaid work in and around the home is a common and potentially high risk activity, yet there is limited information about the circumstances surrounding resulting injuries. This study aimed to describe circumstances surrounding fatal injuries resulting from home duties activities, in order to identify and prioritise areas for prevention. DESIGN AND SETTING Coroners' reports on all unintentional deaths in Australia from 1989-92 inclusive were inspected to identify deaths of interest. Rates were calculated using population data and incorporating measures of time engaged in particular home duties activities. RESULTS There were 296 home duties deaths over the four year period. Most (83%) deaths were of males, and males had 10 times the risk of fatal injury compared with females. The most common activities resulting in fatal injuries were home repairs, gardening, and car care. The highest risk activities (deaths per million persons per year per hour of activity) were home repairs (49), car care (20), home improvements (18), and gardening (16). Being hit by inadequately braced vehicles during car maintenance, falls from inadequately braced ladders, contact with fire and flames while cooking, and contact with electricity during maintenance were the most common injury scenarios. CONCLUSIONS Fatal injury of persons engaged in unpaid domestic work activities is a significant cause of death. Use of activity specific denominator data allows appropriate assessment of the degree of risk associated with each activity. The recurrence of similar circumstances surrounding many independent fatal incidents indicates areas where preventative interventions might be usefully targeted.
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Hiers JK, Mitchell RJ, Boring LR, Hendricks JJ, Wyatt R. Legumes native to longleaf pine savannas exhibit capacity for high N 2 -fixation rates and negligible impacts due to timing of fire. THE NEW PHYTOLOGIST 2003; 157:327-338. [PMID: 33873644 DOI: 10.1046/j.1469-8137.2003.00679.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
• N2 fixation rates of three legume species and the impact of fire regime are reported. • Summer, winter, and no burn treatments were applied. N 2 fixation rates ( 15 N isotope dilution) and C trade-offs with flowering and fine root turnover were examined in response to season of burn. • Tephrosia and Centrosema had uniformly high percentage N dfa across all treatments (74-92% N dfa ), whereas Rhynchosia showed limited N 2 fixation activity (18% and 0%). No evidence for decreased N 2 fixation due to loss of leaf area following growing season burns was found. Moreover, no consistent evidence for decreased N 2 fixation with greater flowering or fine root turnover was observed. • Despite species differences in response to fire regime, the following patterns emerged: when increased N 2 fixation is associated with decreased growth rates, legumes show limited N 2 fixation rates (as seen in Rhynchosia ). Alternatively, if greater N 2 fixation is related to increased growth rates, then legumes experience C limitations to N 2 fixation only in small individuals or during periods of rapid growth (as in Centrosema ). Reproduction may influence N 2 -fixation, but, as in the case of Tephrosia , the relationship was positive, opposite to patterns indicative of C trade-offs.
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Mitchell RJ, Farrington SM, Dunlop MG, Campbell H. Mismatch repair genes hMLH1 and hMSH2 and colorectal cancer: a HuGE review. Am J Epidemiol 2002; 156:885-902. [PMID: 12419761 DOI: 10.1093/aje/kwf139] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Evidence to support a role for the mismatch repair genes human mutL homolog 1 (hMLH1) and human mutS homolog 2 (hMSH2) in the etiology of colorectal cancer has come from linkage analysis, segregation studies, and molecular biologic analysis. More recently, carriers of potentially pathogenic mutations in the hMLH1/hMSH2 genes have consistently been shown to be at a greatly increased risk of developing colorectal cancer compared with the general population. When considered together, the available evidence shows a strong, consistent, and biologically plausible association between mismatch repair gene mutations and colorectal cancer. The penetrance of mutations in hMLH1/hMSH2 is incomplete and is significantly higher in males (approximately 80%) than in females (approximately 40%). To date, evidence for gene-gene or gene-environment interactions is limited, although preliminary studies have revealed a number of avenues that merit exploration. Population screening for mutation carriers is not currently a feasible option, and mutation analysis remains restricted to either relatives of mutation carriers or colorectal cancer cases selected on the basis of phenotype.
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Lamsis F, Flannery GR, White NG, Muratore R, Kaelan C, Mitchell RJ. Alleles and haplotypes of tumor necrosis factor (TNF) alpha and beta genes in three ethnic populations of Sulawesi Indonesia. Hum Biol 2002; 74:381-96. [PMID: 12180762 DOI: 10.1353/hub.2002.0030] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Polymorphic variation in two cytokine genes, tumor necrosis factor (TNF) -alpha and -beta, was examined in three ethnic groups, the Bugis, the Makassans, and the Torajans, who inhabit Sulawesi, a large island in the Indonesian archipelago, and formerly a Dutch colony. TNF-alpha and -beta are key molecules in immune responses to infection, and both have been implicated in the pathogenesis and clinical manifestations of parasitic diseases. Several polymorphic variants with the potential to affect cytokine levels in autoimmune diseases and parasitic and bacterial infection have been reported. Two loci in the promoter region of TNF-alpha and two sites in the first intron of TNF-beta were scored in a maximum of 150 Bugis, 168 Makassans, and 58 Torajans. Genotypes at the two TNF-alpha loci are not in Hardy-Weinberg equilibrium because of a deficit of heterozygotes (p < 0.05). However, genotypes at the TNF-beta loci exhibit Hardy-Weinberg equilibrium. A comparison of allelic and genotypic frequencies at all TNF loci across the ethnic groups reveals that the differences are significant for TNFalpha(308) (p < 0.01) and for TNFbeta(NcoI) (p < 0.05). Overall, the distribution of the alleles differs from that seen in the few Asian populations for which data are available (p < 0.05). Construction of 4-locus haplotypes showed that, in addition to the five previously reported, four novel haplotypes were present in Sulawesi. These novel haplotypes were in low frequency, and two were seen only in Bugis (haplotypes F and J) and one (haplotype K) only in Makassans. The other, haplotype D, was present in Makassans and Torajans. Preliminary sampling of other ethnic groups suggests that three of these haplotypes (D, F, and J) may be restricted to Asian or Asian-derived populations. The frequency of the common TNF haplotypes differed between Dutch and Sulawesi populations, and these data also indicated that haplotype E, which has a relatively high frequency in the Dutch (25%), may be a useful marker of Dutch/European admixture in Indonesian populations, in which it is either rare (1%) or absent. The results suggest that unique allelic combinations with potential to influence cytokine secretion are present in Sulawesi, possibly as a consequence of parasite-driven selection, and argue for more extensive investigation of haplotype distribution in parasite-endemic areas.
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Mulligan MK, Kirkman LK, Mitchell RJ. Aristida beyrichiana (Wiregrass) Establishment and Recruitment: Implications for Restoration. Restor Ecol 2002. [DOI: 10.1046/j.1526-100x.2002.10107.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Franklin RC, Mitchell RJ, Driscoll TR, Fragar LJ. Agricultural work-related fatalities in Australia, 1989-1992. J Agric Saf Health 2001; 7:213-27. [PMID: 11787751 DOI: 10.13031/2013.6218] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Farm-related fatalities in Australia were studied as part of a larger study of all work-related traumatic fatalities from 1989-1992. Information concerning 373 unintentional work-related fatalities was obtained from inspection of coronial files and described. The fatality rate per 100,000 workers was four times higher for agricultural industry workers (20.6) compared to the all-industry rate during the same time frame (5.5). Males comprised 95% of all agricultural work-related deaths. Agents such as farm vehicles, mobile farm machinery (mainly tractors), and farm structures (mainly dams) were among the most common involved in the fatal incident. Being hit by moving objects, vehicle accidents, and rollovers of mobile machinery (mainly tractors) were among the most common mechanisms of fatal injury on farms. Transport for work purposes, working with animals, working with crops, and maintenance were the most common activities being undertaken. The information obtained from this study is being used to develop health and safety risk profiles for agricultural industries, and these profiles are being used in turn to develop guidance material for farmers, on-farm checklists, and other tools to help farmers manage their occupational health and safety risk.
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Franklin RC, Mitchell RJ, Driscoll TR, Fragar LJ. Non-work-related farm fatalities in Australia, 1989-1992. J Agric Saf Health 2001; 7:229-39. [PMID: 11787752 DOI: 10.13031/2013.6219] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This study aims to examine farm fatalities, between 1989-1992 in Australia, of individuals not working at the time of the incident. Non-work-related farm fatalities in Australia were studied as part of a larger study of all work-related traumatic fatalities from 1989-1992. Information on 214 unintentional non-work-related farm fatalities was obtained from inspection of coronial files. The information was examined according to type of bystander (bystander to work or bystander to farm equipment) and other farm deaths. Agents such as dams, tractors, utilities, and cars were among the most common causes of death for bystanders involved in fatal incidents. Fire and smoke, creeks or rivers, and cars were the most common agents for other farm deaths. Drowning, vehicle accidents, and being hit by moving objects were among the most common mechanisms of fatal injury for non-work-related farm deaths. The information gained from this study has been used to develop the Child Safety on Farms Strategy for Farmsafe Australia and Farmsafe Australia's Farm Machinery Safety Strategy.
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