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Conway DJ, Roper C, Oduola AM, Arnot DE, Kremsner PG, Grobusch MP, Curtis CF, Greenwood BM. High recombination rate in natural populations of Plasmodium falciparum. Proc Natl Acad Sci U S A 1999; 96:4506-11. [PMID: 10200292 PMCID: PMC16362 DOI: 10.1073/pnas.96.8.4506] [Citation(s) in RCA: 195] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Malaria parasites are sexually reproducing protozoa, although the extent of effective meiotic recombination in natural populations has been debated. If meiotic recombination occurs frequently, compared with point mutation and mitotic rearrangement, linkage disequilibrium between polymorphic sites is expected to decline with increasing distance along a chromosome. The rate of this decline should be proportional to the effective meiotic recombination rate in the population. Multiple polymorphic sites covering a 5-kb region of chromosome 9 (the msp1 gene) have been typed in 547 isolates from six populations in Africa to test for such a decline and estimate its rate in populations of Plasmodium falciparum. The magnitude of two-site linkage disequilibrium declines markedly with increasing molecular map distance between the sites, reaching nonsignificant levels within a map range of 0.3-1.0 kb in five of the populations and over a larger map distance in the population with lowest malaria endemicity. The rate of decline in linkage disequilibrium over molecular map distance is at least as rapid as that observed in most chromosomal regions of other sexually reproducing eukaryotes, such as humans and Drosophila. These results are consistent with the effective recombination rate expected in natural populations of P. falciparum, predicted on the basis of the underlying molecular rate of meiotic crossover and the coefficient of inbreeding caused by self-fertilization events. This is conclusive evidence to reject any hypothesis of clonality or low rate of meiotic recombination in P. falciparum populations. Moreover, the data have major implications for the design and interpretation of population genetic studies of selection on P. falciparum genes.
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195 |
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Conway DJ, Cavanagh DR, Tanabe K, Roper C, Mikes ZS, Sakihama N, Bojang KA, Oduola AM, Kremsner PG, Arnot DE, Greenwood BM, McBride JS. A principal target of human immunity to malaria identified by molecular population genetic and immunological analyses. Nat Med 2000; 6:689-92. [PMID: 10835687 DOI: 10.1038/76272] [Citation(s) in RCA: 189] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
New strategies are required to identify the most important targets of protective immunity in complex eukaryotic pathogens. Natural selection maintains allelic variation in some antigens of the malaria parasite Plasmodium falciparum. Analysis of allele frequency distributions could identify the loci under most intense selection. The merozoite surface protein 1 (Msp1) is the most-abundant surface component on the erythrocyte-invading stage of P. falciparum. Immunization with whole Msp1 has protected monkeys completely against homologous and partially against non-homologous parasite strains. The single-copy msp1 gene, of about 5 kilobases, has highly divergent alleles with stable frequencies in endemic populations. To identify the region of msp1 under strongest selection to maintain alleles within populations, we studied multiple intragenic sequence loci in populations in different regions of Africa and Southeast Asia. On both continents, the locus with the lowest inter-population variance in allele frequencies was block 2, indicating selection in this part of the gene. To test the hypothesis of immune selection, we undertook a large prospective longitudinal cohort study. This demonstrated that serum IgG antibodies against each of the two most frequent allelic types of block 2 of the protein were strongly associated with protection from P. falciparum malaria.
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Duraisingh MT, Roper C, Walliker D, Warhurst DC. Increased sensitivity to the antimalarials mefloquine and artemisinin is conferred by mutations in the pfmdr1 gene of Plasmodium falciparum. Mol Microbiol 2000; 36:955-61. [PMID: 10844681 DOI: 10.1046/j.1365-2958.2000.01914.x] [Citation(s) in RCA: 135] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The declining efficacy of chloroquine and pyrimethamine/sulphadoxine in the treatment of human malaria has led to the use of newer antimalarials such as mefloquine and artemisinin. Sequence polymorphisms in the pfmdr1 gene, the gene encoding the plasmodial homologue of mammalian multidrug resistance transporters, have previously been linked to resistance to chloroquine in some, but not all, studies. In this study, we have used a genetic cross between the strains HB3 and 3D7 to study inheritance of sensitivity to the structurally unrelated drugs mefloquine and artemisinin, and to several other antimalarials. We find a complete allelic association between the HB3-like pfmdr1 allele and increased sensitivity to these drugs in the progeny. Different pfmdr1 sequence polymorphisms in other unrelated lines were also associated with increased sensitivity to these drugs. Our results indicate that the pfmdr1 gene is an important determinant of susceptibility to antimalarials, which has major implications for the future development of resistance.
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135 |
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Roper C, Elhassan IM, Hviid L, Giha H, Richardson W, Babiker H, Satti GM, Theander TG, Arnot DE. Detection of very low level Plasmodium falciparum infections using the nested polymerase chain reaction and a reassessment of the epidemiology of unstable malaria in Sudan. Am J Trop Med Hyg 1996; 54:325-331. [PMID: 8615441 DOI: 10.4269/ajtmh.1996.54.325] [Citation(s) in RCA: 124] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
We have used the nested polymerase chain reaction (PCR) to assay for low level Plasmodium falciparum infections that were below the threshold of detection of blood film examination. This revealed a substantial group of asymptomatic, submicroscopically patent infections within the population of a Sudanese village present throughout the year although clinical malaria episodes were almost entirely confined to the transmission season. In our September, January, April, and June surveys, the PCR-detected prevalences were 13%, 19%, 24%, and 19%, respectively. These figures reveal a much higher prevalence of dry season infection than previous microscopic surveys have indicated. Furthermore, 20% of a cohort of 79 individuals were healthy throughout the September to November transmission season but were PCR-positive for P. falciparum in a least one of a series of samples taken in the ensuing months. Levels of exposure to P. falciparum infection were therefore higher than was previously believed in this region, highlighting the fact that many individuals were infected but healthy for most of the year. The reservoir parasite population was thus larger and more stable than previously thought, a finding that is consistent with the high levels of genetic variation at polymorphic loci reported from analysis of P. falciparum parasites in this area.
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124 |
5
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Conway DJ, Fanello C, Lloyd JM, Al-Joubori BM, Baloch AH, Somanath SD, Roper C, Oduola AM, Mulder B, Povoa MM, Singh B, Thomas AW. Origin of Plasmodium falciparum malaria is traced by mitochondrial DNA. Mol Biochem Parasitol 2000; 111:163-71. [PMID: 11087926 DOI: 10.1016/s0166-6851(00)00313-3] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The origin and geographical spread of Plasmodium falciparum is here determined by analysis of mitochondrial DNA sequence polymorphism and divergence from its most closely related species P. reichenowi (a rare parasite of chimpanzees). The complete 6 kb mitochondrial genome was sequenced from the single known isolate of P. reichenowi and from four different cultured isolates of P. falciparum, and aligned with the two previously derived P. falciparum sequences. The extremely low synonymous nucleotide polymorphism in P. falciparum (pi=0.0004) contrasts with the divergence at such sites between the two species (kappa=0.1201), and supports a hypothesis that P. falciparum has recently emerged from a single ancestral population. To survey the geographical distribution of mitochondrial haplotypes in P. falciparum, 104 isolates from several endemic areas were typed for each of the identified single nucleotide polymorphisms. The haplotypes show a radiation out of Africa, with unique types in Southeast Asia and South America being related to African types by single nucleotide changes. This indicates that P. falciparum originated in Africa and colonised Southeast Asia and South America separately.
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Giha HA, Staalsoe T, Dodoo D, Roper C, Satti GM, Arnot DE, Hviid L, Theander TG. Antibodies to variable Plasmodium falciparum-infected erythrocyte surface antigens are associated with protection from novel malaria infections. Immunol Lett 2000; 71:117-126. [PMID: 10714439 DOI: 10.1016/s0165-2478(99)00173-x] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In areas of unstable transmission malaria affects all age groups, but the malaria incidence is lower in adults compared to children and teenagers. Under such conditions subclinical Plasmodium falciparum infections are common and some infections are controlled, because blood parasitaemia is maintained at low densities. Here, we test the hypothesis that the presence or absence of antibodies against variant antigens on the surface of P. falciparum-infected erythrocytes protect individuals against some infectious challenges and render them susceptible to others. Plasma collected in Daraweesh, eastern Sudan, before and after the malaria season from individuals who had (susceptible) or did not have malaria (protected) during the season, were tested for reactivity against variant antigens on the surface of nine parasite isolates by flow cytometry. Both protected and susceptible individuals acquired antibodies to variant antigens during the malaria season. The presence of antibody to a Ghanaian isolate before the season was statistically significantly associated with protection against malaria. When considering all nine isolates, the patterns of antibody acquisition differed between susceptible and protected individuals. Together, the results indicate that pre-existing anti-PfEMP1 antibodies can reduce the risk of contracting clinical malaria when challenged by novel parasite clones expressing homologous, but not heterologous variable surface antigens. The results also confirm that antibodies to variant antigens are induced by both clinical and subclinical infections, and that antibodies against several var sero-types are induced during an infection.
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Giha HA, Staalsoe T, Dodoo D, Elhassan IM, Roper C, Satti GM, Arnot DE, Theander TG, Hviid L. Nine-year longitudinal study of antibodies to variant antigens on the surface of Plasmodium falciparum-infected erythrocytes. Infect Immun 1999; 67:4092-4098. [PMID: 10417178 PMCID: PMC96708 DOI: 10.1128/iai.67.8.4092-4098.1999] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/1999] [Accepted: 05/18/1999] [Indexed: 11/20/2022] Open
Abstract
PfEMP1 is an antigenically variable molecule which mediates the adhesion of parasitized erythrocytes to a variety of cell types and which is believed to constitute an important target for naturally acquired protective immune responses in malaria. For 9 years we have monitored individuals living in an area of low-intensity, seasonal, and unstable malaria transmission in eastern Sudan, and we have used this database to study the acquisition, specificity, and duration of the antibody response to variant parasitized erythrocyte surface antigens. Both the levels and the spectrum of reactivity of these antibodies varied considerably among individuals, ranging from low levels of antibodies recognizing only few parasitized erythrocyte surface antigens to high levels of broad-specificity antibodies. In general, episodes of clinical malaria were associated with increases in the levels of parasitized erythrocyte surface-specific antibodies that subsided within months of the attack. This response was often, but not always, specific for the antigenic variants expressed by the parasite isolate causing disease. Our study provides evidence that Palciparum falciparum malaria is associated with a short-lived, variant-specific antibody response to PfEMP1-like antigens exposed on the surface of parasitized erythrocytes. Furthermore, our data suggest that the antigenic repertoires of variant antigens expressed by different parasite isolates show considerable overlapping, at least under Sahelian conditions of low-intensity, seasonal, and unstable malaria transmission. Finally, we demonstrate the existence of persistent differences among individuals in the capacity to mount antibody responses to variant surface antigens.
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Gooding P, McSherry B, Roper C. Preventing and reducing 'coercion' in mental health services: an international scoping review of English-language studies. Acta Psychiatr Scand 2020; 142:27-39. [PMID: 31953847 PMCID: PMC7496148 DOI: 10.1111/acps.13152] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/12/2020] [Indexed: 11/30/2022]
Abstract
This article discusses initiatives aimed at preventing and reducing 'coercive practices' in mental health and community settings worldwide, including in hospitals in high-income countries, and in family homes and rural communities in low- and middle-income countries. The article provides a scoping review of the current state of English-language empirical research. It identifies several promising opportunities for improving responses that promote support based on individuals' rights, will and preferences. It also points out several gaps in research and practice (including, importantly, a gap in reviews of non-English-language studies). Overall, many studies suggest that efforts to prevent and reduce coercion appear to be effective. However, no jurisdiction appears to have combined the full suite of laws, policies and practices which are available, and which taken together might further the goal of eliminating coercion.
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Scoping Review |
5 |
64 |
9
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Roper C, Richardson W, Elhassan IM, Giha H, Hviid L, Satti GM, Theander TG, Arnot DE. Seasonal changes in the Plasmodium falciparum population in individuals and their relationship to clinical malaria: a longitudinal study in a Sudanese village. Parasitology 1998; 116 ( Pt 6):501-510. [PMID: 9651932 DOI: 10.1017/s0031182098002650] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Residents of Daraweesh village in Sudan were monitored for Plasmodium falciparum infection and malaria morbidity in 3 malaria seasons from 1993 to 1996. Malaria parasites were detected microscopically and by polymerase chain reaction (PCR) in a series of cross-sectional surveys. PCR revealed submicroscopical infections during the dry season, particularly among individuals who had recovered from a malaria episode following successful drug treatment. Clinical and subclinical infections were contrasted by assaying for allelic polymorphism at 2 gene loci, MSP-1 and GLURP and 2 hypotheses examined with reference to these data: that clinical malaria is associated with infection with novel parasite genotypes not previously detected in that host, or alternatively, that clinical malaria episodes are associated with an increased number of clones in an infection. We detected more mixed infections among clinical isolates, but people carrying parasites during the dry season were not found to have an increased risk of disease in the following malaria season. There was a clear association of disease with the appearance of novel parasite genotypes.
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10
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Happell B, Roper C. The role of a mental health consumer in the education of postgraduate psychiatric nursing students: the students' evaluation. J Psychiatr Ment Health Nurs 2003; 10:343-50. [PMID: 12755920 DOI: 10.1046/j.1365-2850.2003.00599.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Recent Australian Government policy reflects the integral nature of active consumer participation to the planning and delivery of mental health services. The effectiveness of consumer participation in improving mental health services has received some attention in the literature. Commonwealth Government funding enabled the development of a partnership between the Centre for Psychiatric Nursing Research and Practice and the Melbourne Consumer Consultants' Group. The successful application enabled the employment of a mental health consumer as an academic staff member of the Centre for Psychiatric Nursing Research and Practice. One important aspect of this role involved the mental health consumer teaching a consumer perspective to postgraduate psychiatric nursing students. The primary aim was to increase the students' awareness of and sensitivity to greater consumer participation within the mental health arena. This paper presents the results of an evaluation of the consumer academic role in teaching within the Postgraduate Diploma in Advanced Clinical Nursing (Psychiatric Nursing). An evaluation form was distributed to students (n = 21) on completion of the semester. The findings suggest the experience was considered beneficial to students and was impacting significantly on their current practice. This project supports the value of consumer participation in the education of mental health professionals.
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22 |
56 |
11
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Conway DJ, Machado RL, Singh B, Dessert P, Mikes ZS, Povoa MM, Oduola AM, Roper C. Extreme geographical fixation of variation in the Plasmodium falciparum gamete surface protein gene Pfs48/45 compared with microsatellite loci. Mol Biochem Parasitol 2001; 115:145-56. [PMID: 11420101 DOI: 10.1016/s0166-6851(01)00278-x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Comparing patterns of genetic variation at multiple loci in the genome of a species can potentially identify loci which are under selection. The large number of polymorphic microsatellites in the malaria parasite Plasmodium falciparum are available markers to screen for selectively important loci. The Pfs48/45 gene on Chromosome 13 encodes an antigenic protein located on the surface of parasite gametes, which is a candidate for a transmission blocking vaccine. Here, genotypic data from 255 P. falciparum isolates are presented, which show that alleles and haplotypes of five single nucleotide polymorphisms (SNPs) in the Pfs48/45 gene are exceptionally skewed in frequency among different P. falciparum populations, compared with alleles at 11 microsatellite loci sampled widely from the parasite genome. Fixation indices measuring inter-population variance in allele frequencies (F(ST)) were in the order of four to seven times higher for Pfs48/45 than for the microsatellites, whether considered (i) among populations within Africa, or (ii) among different continents. Differing mutational processes at microsatellite and SNP loci could generally affect the population structure at these different types of loci, to an unknown extent which deserves further investigation. The highly contrasting population structure may also suggest divergent selection on the amino acid sequence of Pfs48/45 in different populations, which plausibly indicates a role for the protein in determining gamete recognition and compatibility.
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Comparative Study |
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Roper C, Pignatelli P, Partridge L. Evolutionary responses of Drosophila melanogaster life history to differences in larval density. J Evol Biol 1996. [DOI: 10.1046/j.1420-9101.1996.9050609.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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46 |
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Swarthout TD, van den Broek IV, Kayembe G, Montgomery J, Pota H, Roper C. Artesunate�+�amodiaquine and artesunate�+�sulphadoxine?pyrimethamine for treatment of uncomplicated malaria in Democratic Republic of Congo: a clinical trial with determination of sulphadoxine and pyrimethamine-resistant haplotypes. Trop Med Int Health 2006; 11:1503-11. [PMID: 17002724 DOI: 10.1111/j.1365-3156.2006.01710.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We undertook a trial of artesunate + amodiaquine (AS + AQ) and artesunate + sulphadoxine-pyrimethamine (AS + SP) in 180 children of age 6-59 months with uncomplicated malaria in Democratic Republic of Congo. Children were randomly allocated to receive 3 days observed treatment of AS + AQ (n = 90) or 3 days of AS + SP (n = 90). Primary efficacy outcomes were 28-day parasite recurrence rates, and recrudescence rates were adjusted by genotyping to distinguish new infection and recrudescence. In addition, we determined the prevalence of molecular markers of resistance to sulphadoxine and pyrimethamine. Day 28 parasite recurrence rates were 16.9% (14/83; 95% CI: 9.5-26.7) in the AS + AQ group and 34.6% (28/81; 95% CI: 24.3-46.0) in the AS + SP group (P = 0.009). After PCR correction, recrudescence rates were 6.7% (5/74; 95% CI: 2.2-15.1) for AS + AQ and 19.7% (13/66; 95% CI: 10.9-31.3) for AS + SP (P = 0.02). There was no significant difference between the two arms in time to parasite clearance, fever clearance and gametocyte clearance. Parasite genotyping showed high frequencies of dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps) molecular SP-resistance markers, with 57% of the samples showing more than three mutations linked to SP resistance, and 27% with triple-dhfr/double-dhps haplotype, confirming that SP treatment failure rates are likely to be high. AS + AQ had significantly higher efficacy than AS + SP. These results contributed to the subsequent change to AS + AQ as first-line regimen in the country. Efforts to properly implement the new protocol and maintain adherence at acceptable levels should include health staff and patient sensitization. The 6.8% recrudescence rate indicates that AS + AQ should be monitored closely until a more effective artemisinin combination therapy regimen is needed and can be introduced.
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Balogh GJ, Adler SJ, VanderWoude J, Glazer HS, Roper C, Weyman PJ. Pneumothorax as a complication of feeding tube placement. AJR Am J Roentgenol 1983; 141:1275-7. [PMID: 6417991 DOI: 10.2214/ajr.141.6.1275] [Citation(s) in RCA: 39] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Case Reports |
42 |
39 |
15
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Elvidge H, Challis JR, Robinson JS, Roper C, Thorburn GD. Influence of handling and sedation on plasma cortisol in rhesus monkeys (Macaca mulatta). J Endocrinol 1976; 70:325-6. [PMID: 823287 DOI: 10.1677/joe.0.0700325] [Citation(s) in RCA: 38] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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49 |
38 |
16
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Roman MC, Gray D, Luo G, McClanahan R, Perez R, Roper C, Roscoe V, Shevchuk C, Suen E, Sullivan D, Walther HJ. Determination of Ephedrine Alkaloids in Botanicals and Dietary Supplements by HPLC-UV: Collaborative Study. J AOAC Int 2019. [DOI: 10.1093/jaoac/87.1.1] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Abstract
An international collaborative study was conducted of a high-performance liquid chromatography (HPLC)-UV method for the determination of the major (ephedrine [EP] and pseudoephedrine [PS]) and minor (norephedrine [NE], norpseudoephedrine [NP], methylephedrine [ME], and methylpseudoephedrine [MP]) alkaloids in selected dietary supplements representative of the commercially available products. Ten collaborating laboratories determined the ephedrine-type alkaloid content in 8 blind replicate samples. Five products contained ephedra ground herb or ephedra extract. These 5 products included ground botanical raw material of Ephedra sinica, a common powdered extract of Ephedra sinica, a finished product containing only Ephedra sinica ground botanical raw material, a complex multicomponent dietary supplement containing Ma Huang, and a high-protein chocolate flavored drink mix containing Ma Huang extract. In addition, collaborating laboratories received a negative control and negative control spiked with ephedrine alkaloids at high and low levels for recovery studies. Test extracts were treated to solid-phase extraction using a strong-cation exchange column to help remove interferences. The HPLC analyses were performed on a polar-embedded phenyl column using UV detection at 210 nm. Repeatability relative standard deviations (RSD r) ranged from 0.64–3.0% for EP and 2.0–6.6% for PS, excluding the high protein drink mix. Reproducibility relative standard deviations (RSD R) ranged from 2.1–6.6% for EP and 9.0–11.4% for PS, excluding the high protein drink mix. Recoveries ranged from 84.7–87.2% for EP and 84.6–98.2% for PS. The data developed for the minor alkaloids are more variable with generally unsatisfactory HORRATS (i.e., >2). However, since these alkaloids generally add little to the total alkaloid content of the products, the method gives satisfactory results in measuring total alkaloid content (RSD r 0.85–3.13%; RSDR 2.03–10.97%, HORRAT 0.69–3.23, exclusive of the results from the high protein drink). On the basis of these results, the method is recommended for Official First Action for determination of EP and PS in dietary supplements exclusive of the high protein drinks.
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Giha HA, Staalsoe T, Dodoo D, Elhassan IM, Roper C, Satti GM, Arnot DE, Hviid L, Theander TG. Overlapping antigenic repertoires of variant antigens expressed on the surface of erythrocytes infected by Plasmodium falciparum. Parasitology 1999; 119 ( Pt 1):7-17. [PMID: 10446700 DOI: 10.1017/s0031182099004485] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Antibodies against variable antigens expressed on the surface of Plasmodium falciparum-infected erythrocytes are believed to be important for protection against malaria. A target for these antibodies is the P. falciparum erythrocyte membrane protein 1, PfEMP1, which is encoded by around 50 var genes and undergoes clonal variation. Using agglutination and mixed agglutination tests and flow cytometry to analyse the recognition of variant antigens on parasitized erythrocytes by plasma antibodies from individuals living in Daraweesh in eastern Sudan, an area of seasonal and unstable malaria transmission, we show that these antibodies recognize different variant antigens expressed by parasites of different genotype. Comparing the levels and acquisition of antibody to variant antigens in pairs of parasite isolates expressing different variant types, there is a correlation between the acquisition of antibodies to some combinations of variant antigens but not to others. These results indicate that (1) a single infection will induce the production of antibodies recognizing several variants of surface-expressed antigens, (2) the repertoire of variable antigens expressed by different parasites is overlapping and the degree of overlap differs between isolates, and (3) the expression of at least some variant antigens is genetically linked.
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Arnot DE, Roper C, Bayoumi RA. Digital codes from hypervariable tandemly repeated DNA sequences in the Plasmodium falciparum circumsporozoite gene can genetically barcode isolates. Mol Biochem Parasitol 1993; 61:15-24. [PMID: 8259128 DOI: 10.1016/0166-6851(93)90154-p] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
DNA typing systems currently used in parasitology involve either hybridising Southern blots with repetitive sequence probes or amplifying genomic sequences using the polymerase chain reaction (PCR). Both such approaches assay allelic length variation, usually in unexpressed tandemly repeated DNA sequences. Where an appropriate target locus exists, an alternative PCR-based strategy which reveals allelic sequence variation in tandemly repeated DNA offers a more accurate and internally controlled assay. We describe such a strategy for the rapid extraction of information on tandem repeat sequence variation from hypervariable alleles, and apply it to the Plasmodium falciparum CS gene. The extreme variability of such DNA 'barcodes' can be used to identify parasite stocks and lineages. This system is also potentially useful for population genetic and epidemiological studies since it offers the possibility of following the spread of distinctively marked parasite genotypes in samples taken from infected individuals.
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34 |
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Giha HA, Theander TG, Staalsø T, Roper C, Elhassan IM, Babiker H, Satti GM, Arnot DE, Hviid L. Seasonal variation in agglutination of Plasmodium falciparum-infected erythrocytes. Am J Trop Med Hyg 1998; 58:399-405. [PMID: 9574782 DOI: 10.4269/ajtmh.1998.58.399] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Agglutination and rosette formation are in vitro characteristics of Plasmodium falciparum-infected erythrocytes, which have been associated with host protective immune responses and also with parasite virulence. The present study was carried out in an area of seasonal and unstable malaria transmission in eastern Sudan. Plasma samples were obtained before, during, and after the transmission season from a volunteer cohort of 64 individuals seven years of age and older. These plasmas were assayed for their ability to agglutinate cultured parasitized erythrocytes originally obtained from acute malaria infection samples taken from five of the cohort members. Our data show that the capacity of donor plasma samples to agglutinate parasitized cells depended largely on the time of sampling relative to the transmission season, at least within this epidemiologic setting. Thus, although less than half of the pretransmission season samples could agglutinate any of the five lines of cultured parasites, all post-transmission season samples could agglutinate at least one of the parasite lines, with 74% agglutinating two or more lines. This increase in the agglutination capacity of individual plasma samples after the transmission season occurred essentially regardless of whether an individual had experienced a clinical malaria attack during the transmission season. The study thus confirms the acquisition of agglutinating antibodies following episodes of clinical malaria, but also demonstrates that such acquisition can take place in the absence of disease, presumably as a consequence of subclinical infection. This is the first demonstration of marked seasonal fluctuations in the capacity of individuals' sera to agglutinate parasitized red blood cells. Possible explanations for this effect include a decrease in the levels of agglutinating antibodies between seasons, or shifts in the antigens being recognized by such antibodies from one transmission season to the next. Finally, we showed the existence of marked seasonal fluctuation in the levels of agglutinating antibodies, either because levels of such antibodies are not sustained between seasons or because the antigens recognized change from one season to the next.
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Abstract
Malignant fibrous histiocytoma (MFH) is among the most common soft tissue sarcomas of adult life, but rarely occurs elsewhere. We report an example of primary MFH of the lung and review 15 previously reported acceptable cases with current follow-up information. Histologically, the tumor in our case was pleomorphic with storiform and fascicular areas. Tumor cells showed positive immunostaining for alpha 1-antitrypsin, alpha 1-antichymotrypsin, and vimentin. Stains for desmin, cytokeratin, myoglobin, epithelial membrane antigen, S-100 protein, and lysozyme were negative. Electron microscopic study showed histiocyte-like, fibroblast-like, intermediate, and undifferentiated tumor cells. A variety of methods were used to treat these patients. Two patients survived for 5 or more years, two were alive and well at 8 and 12 months, respectively, two were alive with metastatic tumor at 3 and 18 months, respectively, and ten patients died of tumor, with an average survival of 1 year.
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Case Reports |
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Schellenberg D, Abdulla S, Roper C. Current Issues for Anti-Malarial Drugs to Control P. falciparum Malaria. Curr Mol Med 2006; 6:253-60. [PMID: 16515515 DOI: 10.2174/156652406776055168] [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: 11/22/2022]
Abstract
Successful malaria control depends heavily on efficacious anti-malarial drugs for the treatment of malaria. Artesunate-containing Combination Treatments (ACT) are increasingly recommended as first line malaria treatment in endemic countries, but implementation of this recommendation is limited by the small number of available and affordable co-formulated anti-malarial drugs. In recent years Intermittent Preventive Treatment has been recommended for malaria control in pregnancy and has been shown to be of potential public health importance in the prevention of malaria and anaemia in children. The use of drugs for malaria treatment or prevention is associated with the development of resistance and recent advances in molecular biology facilitate the evaluation of the impact on drug resistance of new drug-based strategies. This review concentrates on the challenges surrounding the use of ACT, the current understanding of IPT in infants and the use of molecular approaches to enhance our understanding of the effects of interventions on the spread of drug resistance.
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Fonjungo PN, Elhassan IM, Cavanagh DR, Theander TG, Hviid L, Roper C, Arnot DE, McBride JS. A longitudinal study of human antibody responses to Plasmodium falciparum rhoptry-associated protein 1 in a region of seasonal and unstable malaria transmission. Infect Immun 1999; 67:2975-85. [PMID: 10338508 PMCID: PMC96609 DOI: 10.1128/iai.67.6.2975-2985.1999] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Rhoptry-associated protein 1 (RAP1) of Plasmodium falciparum is a nonpolymorphic merozoite antigen that is considered a potential candidate for a malaria vaccine against asexual blood stages. In this longitudinal study, recombinant RAP1 (rRAP1) proteins with antigenicity similar to that of P. falciparum-derived RAP1 were used to analyze antibody responses to RAP1 over a period of 4 years (1991 to 1995) of 53 individuals naturally exposed to P. falciparum malaria. In any 1 year during the study, between 23 and 39% of individuals who had malaria developed immunoglobulin G (IgG) antibodies detectable with at least one rRAP1 protein. However, the anti-RAP1 antibody responses were detected only during or shortly after clinical malarial infections. RAP1 antibody levels declined rapidly (within 1 to 2 months) following drug treatment of the infections. No anti-RAP1 antibodies were usually detected a few months after the end of malaria transmission, during the dry season, or by the start of the next malaria season. Thus, RAP1 IgG responses were very short-lived. The short duration of RAP1 antibody response may explain the apparent lack of response in a surprisingly high proportion of individuals after clinical malarial infections. For some individuals who experienced more than one malarial infection, a higher anti-RAP1 antibody response to subsequent infections than to earlier infections was observed. This suggested secondary responses to RAP1 and thus the development of immunological memory for RAP1.
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Abstract
This paper critiques the conventional concept of 'insight' within the mental status assessment, seeking to unseat its taken-for-granted definition and the status it has acquired in research and practice. Drawing on social theory, consumer perspective and interdisciplinary research, the paper focuses on the impact of 'thin' biomedical understandings of insight, in disqualifying and demoralizing persons subjected to assessment and at the same time creating punitive scrutineers out of well-intentioned practitioners. Nurses and their mental health colleagues are encouraged to reconsider their reliance on the concept of insight. We entertain the alternative idea that insight is a quality of perception that mental health practitioners can cultivate, to more deeply understand their work, culture and the self.
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Review |
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Roper C, Happell B. Reflection without shame--reflection without blame: towards a more collaborative understanding between mental health consumers and nurses. J Psychiatr Ment Health Nurs 2007; 14:85-91. [PMID: 17244010 DOI: 10.1111/j.1365-2850.2007.01047.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
It is now a clear policy expectation that consumers of mental health services be given the opportunity to be active participants in all aspects of mental health service development and delivery. Psychiatric nurses have an important role to play in ensuring opportunities for genuine participation; however, the literature suggests that this role is not always realized in practice. Negative attitudes of health professionals (including nurses) to consumer has been identified as a significant barrier to the realization of this policy goal, with education and training recognized as an important strategy for developing more positive attitudes. This paper describes the implementation of a mental health consumer academic position, through the personal reflections of a nurse academic and a consumer academic. More specifically, the paper addresses the reactions of some nurses to the work of the consumer academic and the apparent feeling of being attacked as nurses. By recognizing this defensiveness, nurses and other health professionals may more effectively move towards promoting consumer participation in mental health care.
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Emami B, Kaiser L, Simpson J, Shapiro S, Roper C, Lockett MA. Postoperative radiation therapy in non-small cell lung cancer. Am J Clin Oncol 1997; 20:441-8. [PMID: 9345326 DOI: 10.1097/00000421-199710000-00003] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
One hundred seventy-three patients with the diagnosis of non-small cell lung cancer (NSCLC) were treated with surgery and postoperative radiation therapy (RT) at the Radiation Oncology Center, Washington University, St. Louis. All patients had been retrospectively reviewed and restaged according to the new American Joint Committee (AJC) staging classification. Seventeen patients were stage I, 69 were stage II, 74 were stage IIIA, and 2 patients were stage IIIB. In 11 patients, accurate staging could not be determined. Indications for postoperative RT were positive surgical margins (32 patients), metastatic hilar nodes (78 patients), and metastatic mediastinal nodes (62 patients). Locoregional control for stages I, II, and IIIA was 85, 75, and 85%, respectively. Five-year actuarial survival was 35% for stage I and 20% for stages II and IIIA. Patients with N0 disease (positive margins) had 5-year survival of 25%, whereas patients with N1 and N2 disease had a 5-year survival of 20%.
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MESH Headings
- Adenocarcinoma/radiotherapy
- Adenocarcinoma/surgery
- Carcinoma, Large Cell/radiotherapy
- Carcinoma, Large Cell/surgery
- Carcinoma, Non-Small-Cell Lung/pathology
- Carcinoma, Non-Small-Cell Lung/radiotherapy
- Carcinoma, Non-Small-Cell Lung/secondary
- Carcinoma, Non-Small-Cell Lung/surgery
- Carcinoma, Squamous Cell/radiotherapy
- Carcinoma, Squamous Cell/surgery
- Female
- Follow-Up Studies
- Humans
- Life Tables
- Lung Neoplasms/pathology
- Lung Neoplasms/radiotherapy
- Lung Neoplasms/surgery
- Lymphatic Metastasis/radiotherapy
- Male
- Neoplasm Recurrence, Local/pathology
- Neoplasm Recurrence, Local/prevention & control
- Neoplasm Staging
- Neoplasm, Residual
- Pneumonectomy
- Radiotherapy Dosage
- Radiotherapy, Adjuvant
- Retrospective Studies
- Survival Analysis
- Survival Rate
- Tomography, X-Ray Computed
- Treatment Outcome
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