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Mortimore M, Merryweather-Clarke AT, Robson KJ, Powell LW. The haemochromatosis gene: a global perspective and implications for the Asia-Pacific region. J Gastroenterol Hepatol 1999; 14:838-43. [PMID: 10535463 DOI: 10.1046/j.1440-1746.1999.01980.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
Mutations in the haemochromatosis (HFE) gene cause most of the cases of hereditary haemochromatosis among people of Northern European ancestry while remaining a rare cause of iron overload among indigenous persons of the Asia-Pacific region. Advances in understanding of the role of the HFE protein product and other recently cloned iron transporters signify an exciting period, as previously unknown components of the iron metabolism pathway are revealed one by one. Epidemiological studies have shown that this gene is more widespread than its phenotypic expression would suggest and that the heterozygous state may be implicated in the expression of other diseases of the liver such as porphyria cutanea tarda, hepatitis C virus infection and non-alcoholic steatohepatitis. The diagnosis, management and ethical implications for clinical practice in the aftermath of this discovery are discussed.
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27
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Kotre CJ, Robson KJ, Simpson W. Improving the visibility of radio-opaque markers in mammography. Br J Radiol 1999; 72:799-801. [PMID: 10624347 DOI: 10.1259/bjr.72.860.10624347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Owing to the high mean film optical densities used in breast screening mammography, and the very high maximum optical densities that can be obtained using modern mammographic film, it is often found that for larger exposures the nominally radio-opaque markers used to identify views, left and right etc., cannot be seen using a normal illuminator. A simple solution to this problem is to back the radio-opaque markers with a thin metal filter chosen to keep the marker information visible over a wide range of exposures. A convenient material for this is copper foil in the form of self-adhesive tape. The improvement in marker contrast produced by this modification is illustrated using point optical density measurements on marked test films produced at the extremes of the mammographic exposure range.
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Flanagan KL, Plebanski M, Akinwunmi P, Lee EA, Reece WH, Robson KJ, Hill AV, Pinder M. Broadly distributed T cell reactivity, with no immunodominant loci, to the pre-erythrocytic antigen thrombospondin-related adhesive protein of Plasmodium falciparum in West Africans. Eur J Immunol 1999; 29:1943-54. [PMID: 10382757 DOI: 10.1002/(sici)1521-4141(199906)29:06<1943::aid-immu1943>3.0.co;2-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Protective immunity to malaria has been achieved in human volunteers utilizing the pre-erythrocytic Plasmodium falciparum antigen, the circumsporozoite protein (CS). However, T cell reactivity to CS is focused on several highly polymorphic T cell epitope regions, potentially limiting the efficacy of any vaccine to specific malaria strains. Another important pre-erythrocytic malaria antigen, the thrombospondin-related adhesive protein (TRAP), can induce protection in animal models of malaria, but knowledge of human T cell responses is limited to the identification of CD8 T cell epitopes, with no CD4 epitopes identified to date. This comprehensive study assessed reactivity to overlapping peptides spanning almost the whole of P. falciparum TRAP (PfTRAP), as well as peptides selected on the basis of HLA class II-binding motifs. A total of 50 naturally exposed Gambian adults were assessed to define 26 T cell epitopes in PfTRAP capable of inducing rapid IFN-gamma or IL-4 production, as assessed by enzyme-linked immunospot assays. In contrast to the CS protein, this reactivity was broadly distributed along the length of TRAP. Moreover, of the 26 epitopes identified, 10 were found to be conserved in West Africa.
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Rochette J, Pointon JJ, Fisher CA, Perera G, Arambepola M, Arichchi DS, De Silva S, Vandwalle JL, Monti JP, Old JM, Merryweather-Clarke AT, Weatherall DJ, Robson KJ. Multicentric origin of hemochromatosis gene (HFE) mutations. Am J Hum Genet 1999; 64:1056-62. [PMID: 10090890 PMCID: PMC1377829 DOI: 10.1086/302318] [Citation(s) in RCA: 116] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Genetic hemochromatosis (GH) is believed to be a disease restricted to those of European ancestry. In northwestern Europe, >80% of GH patients are homozygous for one mutation, the substitution of tyrosine for cysteine at position 282 (C282Y) in the unprocessed protein. In a proportion of GH patients, two mutations are present, C282Y and H63D. The clinical significance of this second mutation is such that it appears to predispose 1%-2% of compound heterozygotes to expression of the disease. The distribution of the two mutations differ, C282Y being limited to those of northwestern European ancestry and H63D being found at allele frequencies>5%, in Europe, in countries bordering the Mediterranean, in the Middle East, and in the Indian subcontinent. The C282Y mutation occurs on a haplotype that extends </=6 Mb, suggesting that this mutation has arisen during the past 2,000 years. The H63D mutation is older and does not occur on such a large extended haplotype, the haplotype in this case extending </=700 kb. Here we report the finding of the H63D and C282Y mutations on new haplotypes. In Sri Lanka we have found H63D on three new haplotypes and have found C282Y on one new haplotype, demonstrating that these mutations have arisen independently on this island. These results suggest that the HFE gene has been the subject of selection pressure. These selection pressures could be due to infectious diseases, environmental conditions, or other genetic disorders such as anemia.
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Naitza S, Spano F, Robson KJ, Crisanti A. The Thrombospondin-related Protein Family of Apicomplexan Parasites: The Gears of the Cell Invasion Machinery. ACTA ACUST UNITED AC 1998; 14:479-84. [PMID: 17040860 DOI: 10.1016/s0169-4758(98)01346-5] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
A number of severe diseases of medical and veterinary importance are caused by parasites of the phylum Apicomplexa. These parasites invade host cells using similar subcellular structures, organelles and molecular species. Proteins containing one or more copies of the type I repeat of human platelet thrombospondin (TSP1), are crucial components of both locomotion and invasion machinery. Members of this family have been identified in Eimeria tenella, E. maxima, Toxoplasma gondii, Cryptosporidium parvum and in all Plasmodium species so far analysed. Here, Andrea Crisanti and colleagues discuss the structure, localization and current understanding of the function of TSP family members in the invasion of target cells by apicomplexan parasites.
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Abstract
BACKGROUND Keratoacanthoma is a common cutaneous neoplasm, although the persistent form is less common and often more difficult to manage. Multiple treatment approaches have been attempted with variable efficacy. Establishing the diagnosis and selecting a treatment plan for persistent keratoacanthoma is often challenging. OBJECTIVE Our purpose is to describe the difficulty one may encounter in the diagnosis and treatment of persistent keratoacanthoma. Hopefully, review of this clinical conundrum may facilitate the management of the reader's future patients. METHODS We describe a case of persistent keratoacanthoma where the diagnosis was initially elusive and the management challenging. Our thought process during each stage of diagnosis and management is described in the form of "issues" with references to the appropriate literature. RESULTS After several diagnostic and therapeutic interventions, successful treatment was achieved with administration of oral isotretinoin. Long-term remission continued as the dosage was tapered. CONCLUSION Persistent keratoacanthoma may be challenging to diagnose and manage, presenting a clinical conundrum. Careful review of the clinicopathologic presentation and an understanding of the various treatment options may result in a successful outcome.
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MESH Headings
- Administration, Oral
- Chemotherapy, Adjuvant
- Combined Modality Therapy
- Dermatologic Surgical Procedures
- Humans
- Isotretinoin/administration & dosage
- Keratoacanthoma/diagnosis
- Keratoacanthoma/drug therapy
- Keratoacanthoma/pathology
- Keratoacanthoma/surgery
- Male
- Middle Aged
- Neoplasm Recurrence, Local/diagnosis
- Neoplasm Recurrence, Local/drug therapy
- Neoplasm Recurrence, Local/pathology
- Neoplasm Recurrence, Local/surgery
- Neoplasms, Multiple Primary/diagnosis
- Neoplasms, Multiple Primary/drug therapy
- Neoplasms, Multiple Primary/pathology
- Neoplasms, Multiple Primary/surgery
- Skin/pathology
- Skin Neoplasms/diagnosis
- Skin Neoplasms/drug therapy
- Skin Neoplasms/pathology
- Skin Neoplasms/surgery
- Treatment Outcome
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32
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Abstract
Many aspects of dermatologic diagnosis are either of importance or interest to the nondermatologist, and there are many excellent textbooks available for guidance. This article focuses on four categories of conditions that are the source of frequent queries from the primary care setting: (1) common skin diseases that frequently mimic systemic illness, (2) common skin diseases that have important systemic associations, (3) common systemic diseases that have prominent cutaneous findings, and (4) the seldom seen but frequently raised concerns regarding cutaneous signs of internal malignancy.
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33
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Pointon JJ, Stone C, Shearman JD, Merryweather-Clarke AT, Rosenberg WM, Robson KJ. More microsatellite markers around D6S105. Mol Cell Probes 1998; 12:181-4. [PMID: 9664581 DOI: 10.1006/mcpr.1998.0162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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34
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Merryweather-Clarke AT, Worwood M, Parkinson L, Mattock C, Pointon JJ, Shearman JD, Robson KJ. The effect of HFE mutations on serum ferritin and transferrin saturation in the Jersey population. Br J Haematol 1998; 101:369-73. [PMID: 9609537 DOI: 10.1046/j.1365-2141.1998.00736.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
High frequencies of the haemochromatosis-related HFE C282Y mutation have been reported in North European populations, in which a high proportion of patients with the disease are homozygotes. However, the degree of penetrance of this genotype is unknown. We determined the HFE C282Y and H63D genotypes of 411 consenting volunteer blood donors on Jersey, and the serum ferritin and transferrin saturation levels of 204 of these volunteers. The C282Y allele frequency was found to be 8.3% in 822 chromosomes, indicating a homozygote frequency of 1/145. Consistent with this, four C282Y homozygotes were detected in 411 volunteers. As there are only 18 patients presently receiving treatment for haemochromatosis on Jersey, out of a total population of about 85000, there is a large discrepancy between the number of haemochromatosis patients and the number of C282Y homozygotes in this population. In a preliminary study of 204 consenting volunteers we found a correlation between transferrin saturation and HFE H63D/ C282Y genotype (P=0.017) and between serum ferritin and genotype (P = 0.056). We also observed elevated values of transferrin saturation in the two C282Y homozygotes assayed. These results suggest that a large proportion of the many undetected C282Y homozygotes on Jersey and in similar populations could be in the preclinical stages of haemochromatosis, and warrant investigation. However, there may be a wide variation in the expression of the condition, and a more extensive study of the level of disease penetrance encompassing a large number of hitherto undetected C282Y homozygotes is therefore imperative.
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35
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Merryweather-Clarke AT, Shearman JD, Robson KJ, Pointon JJ, Liu YT, Bomford A, Dooley J, Walker AP, Worwood M. Hemochromatosis-related mutation detection. Blood 1998; 91:2620-1. [PMID: 9516166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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36
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Schneider J, Gilbert SC, Blanchard TJ, Hanke T, Robson KJ, Hannan CM, Becker M, Sinden R, Smith GL, Hill AV. Enhanced immunogenicity for CD8+ T cell induction and complete protective efficacy of malaria DNA vaccination by boosting with modified vaccinia virus Ankara. Nat Med 1998; 4:397-402. [PMID: 9546783 DOI: 10.1038/nm0498-397] [Citation(s) in RCA: 516] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Immunization with irradiated sporozoites can protect against malaria infection and intensive efforts are aimed at reproducing this effect with subunit vaccines. A particular sequence of subunit immunization with pre-erythrocytic antigens of Plasmodium berghei, consisting of single dose priming with plasmid DNA followed by a single boost with a recombinant modified vaccinia virus Ankara (MVA) expressing the same antigen, induced unprecedented complete protection against P. berghei sporozoite challenge in two strains of mice. Protection was associated with very high levels of splenic peptide-specific interferon-gamma-secreting CD8+ T cells and was abrogated when the order of immunization was reversed. DNA priming followed by MVA boosting may provide a general immunization regime for induction of high levels of CD8+ T cells.
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37
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Shearman JD, Pointon JJ, Merryweather-Clarke AT, Stone C, Horsley SW, Kearney L, Rosenberg WM, Robson KJ. Rapid mapping of markers applying vectorette technology to YAC fragmentation allows easy assembly of a high-density STS bacterial clone contig spanning the markers D6S1260-D6S1918. Mamm Genome 1998; 9:220-5. [PMID: 9501306 DOI: 10.1007/s003359900729] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We have generated a detailed physical map of the 6p21.3/p22.1 boundary, using a combination of yeast artificial chromosome (YAC) fragmentation and high-resolution sequence tagged site (STS) content mapping. YACs from the CEPH, St. Louis, and ICRF libraries have been used to construct a 4.5-Mb contig spanning the markers D6S306 to D6S1571. YAC insert sizes were determined by pulsed field gel electrophoresis (PFGE). Chimerism of YACs was determined by fluorescent in situ hybridization (FISH), and their integrity was determined by fingerprinting with Alu-PCR. We have identified 10 new CA repeat loci in this region as well as over 50 novel STSs, several tRNA genes, a new histone H2B gene and the phospholipase D gene. Using these new markers, we have rapidly generated a bacterial clone contig of over 250 kb, spanning the markers D6S1260 to D6S1918 (WI-3111) with STSs spaced on average every 6 kb.
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38
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Stone MS, Robson KJ, LeBoit PE. Subacute radiation dermatitis from fluoroscopy during coronary artery stenting: evidence for cytotoxic lymphocyte mediated apoptosis. J Am Acad Dermatol 1998; 38:333-6. [PMID: 9486710 DOI: 10.1016/s0190-9622(98)70577-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
A patient with fluoroscopy-induced subacute radiation dermatitis is described. Her biopsy specimen showed vacuolar change and necrotic keratinocytes with lymphocytes in direct apposition, or "satellitosis". Lymphocytes in the dermis and infiltrating the epidermis were predominantly CD8+ and a number of the lymphocytes stained for TIA-1, a cytotoxic granule protein in T-cells and natural killer cells, that appears to be involved in the induction of apoptosis. Our findings suggest cytotoxic lymphocyte mediated apoptosis is involved in the pathogenesis of subacute radiation dermatitis.
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39
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Robson KJ, Dolo A, Hackford IR, Doumbo O, Richards MB, Keita MM, Sidibe T, Bosman A, Modiano D, Crisanti A. Natural polymorphism in the thrombospondin-related adhesive protein of Plasmodium falciparum. Am J Trop Med Hyg 1998; 58:81-9. [PMID: 9452297 DOI: 10.4269/ajtmh.1998.58.81] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
We have developed a typing system using natural sequence variation in the thrombospondin-related adhesive protein (TRAP) gene of Plasmodium falciparum. This method permits a haplotype to be assigned to any particular TRAP gene. We have applied this method to a hospital-based, case control-study in Mali. Previous sequence variation and conservation in TRAP has been confirmed. Particular TRAP haplotypes can be used as geographic hallmarks. Because of the high level of conflict between characters, we have examined the phylogenetic relationships between parasites using a network approach. Having received patient samples from urban and periurban areas of Bamako, the majority of haplotypes were closely related and distinct from TRAP sequences present in other continents. This suggests that the structure of TRAP can only tolerate a limited number of sequence variations to preserve its function but that this is sufficient to allow the parasite to evade the host's immune system until a long-lived immune response can be maintained. It may also reflect host genetics in that certain variants may escape the host immune response more efficiently than others. For vaccine design, sequences from the major regional variants may need to be considered in the production of effective subunit vaccines.
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40
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Worwood M, Raha Chowdhury R, Robson KJ, Pointon J, Shearman JD, Darke C. The HLA A1-B8 haplotype extends 6 Mb beyond HLA-A: associations between HLA-A, B, F and 15 microsatellite markers. TISSUE ANTIGENS 1997; 50:521-6. [PMID: 9389327 DOI: 10.1111/j.1399-0039.1997.tb02908.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Allele frequencies for HLA-A, B and F and 15 microsatellite markers located from 100 kb telomeric to HLA-A to 6 Mb telomeric have been determined in a group of 60 blood donors. Linkage disequilibrium analysis revealed significant haplotype associations even after correction for the number of comparisons made. The HLA-A1, B8 haplotype extends as far as D6S276 (6.0 Mb telomeric to HLA-A). It is important to realize that this common haplotype extends beyond the HLA region, especially when evaluating haplotype associations with particular disorders.
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41
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Merryweather-Clarke AT, Liu YT, Shearman JD, Pointon JJ, Robson KJ. A rapid non-invasive method for the detection of the haemochromatosis C282Y mutation. Br J Haematol 1997; 99:460-3. [PMID: 9375773 DOI: 10.1046/j.1365-2141.1997.4193224.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We describe the rapid single-step detection, by mutagenically separated polymerase chain reaction (MS-PCR), of the HLE C282Y mutation, for which > 90% of haemochromatosis patients in the U.K. are homozygous. In addition to using purified DNA as a template, whole blood and lysed buccal cell extracts from mouthwash samples can be used. Therefore sample collection may be non-invasive and purification steps kept to a minimum.
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42
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Sultan AA, Thathy V, Frevert U, Robson KJ, Crisanti A, Nussenzweig V, Nussenzweig RS, Ménard R. TRAP is necessary for gliding motility and infectivity of plasmodium sporozoites. Cell 1997; 90:511-22. [PMID: 9267031 DOI: 10.1016/s0092-8674(00)80511-5] [Citation(s) in RCA: 458] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Many protozoans of the phylum Apicomplexa are invasive parasites that exhibit a substrate-dependent gliding motility. Plasmodium (malaria) sporozoites, the stage of the parasite that invades the salivary glands of the mosquito vector and the liver of the vertebrate host, express a surface protein called thrombospondin-related anonymous protein (TRAP) that has homologs in other Apicomplexa. By gene targeting in a rodent Plasmodium, we demonstrate that TRAP is critical for sporozoite infection of the mosquito salivary glands and the rat liver, and is essential for sporozoite gliding motility in vitro. This suggests that in Plasmodium sporozoites, and likely in other Apicomplexa, gliding locomotion and cell invasion have a common molecular basis.
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43
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Spaccapelo R, Naitza S, Robson KJ, Crisanti A. Thrombospondin-related adhesive protein (TRAP) of Plasmodium berghei and parasite motility. Lancet 1997; 350:335. [PMID: 9251640 DOI: 10.1016/s0140-6736(97)24031-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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44
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Aidoo M, Lalvani A, Whittle HC, Hill AV, Robson KJ. Recombinant vaccinia viruses for the characterization of Plasmodium falciparum-specific cytotoxic T lymphocytes: recognition of processed antigen despite limited re-stimulation efficacy. Int Immunol 1997; 9:731-7. [PMID: 9184918 DOI: 10.1093/intimm/9.5.731] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Cytotoxic T lymphocytes (CTL) have been implicated in immunity to Plasmodium falciparum infection and disease. We have previously described the use of peptides to define malaria-specific CTL epitopes. To determine whether these peptide epitopes are processed intracellularly from the whole antigen we have developed recombinant vaccinia viruses (rVV) expressing three malaria antigens: thrombospondin-related adhesive protein (TRAP), Pfs16 and the C-terminal half of liver-stage antigen (LSA)-1. Target cells infected with recombinant viruses were lysed by malaria-specific CTL from semi-immune African donors. We also tested the ability of cells infected with these recombinant vaccinia viruses to re-stimulate malaria-specific CTL in peripheral blood lymphocytes from malaria immune adults. Two other pox virus recombinants, NYVAC, an attenuated vaccinia virus, and ALVAC, a canarypox virus, both expressing malaria antigens were also evaluated for their ability to stimulate malaria-specific CTL in contrast to peptide, none of these viruses successfully re-stimulated CTL from the peripheral blood lymphocytes of semi-immune donors. The ability of human CTL from naturally exposed individuals to recognize processed antigen supports the relevance of these cells in protective immunity to malaria.
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MESH Headings
- Adult
- Animals
- Antigen Presentation
- Antigens, Protozoan/biosynthesis
- Antigens, Protozoan/metabolism
- Epitopes, T-Lymphocyte/immunology
- Humans
- Immunization, Secondary
- Lymphocyte Activation
- Malaria, Falciparum/immunology
- Malaria, Falciparum/virology
- Plasmodium falciparum/immunology
- Recombination, Genetic
- T-Lymphocytes, Cytotoxic/immunology
- T-Lymphocytes, Cytotoxic/parasitology
- T-Lymphocytes, Cytotoxic/virology
- Vaccinia virus/genetics
- Vaccinia virus/immunology
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45
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Merryweather-Clarke AT, Pointon JJ, Shearman JD, Robson KJ. Global prevalence of putative haemochromatosis mutations. J Med Genet 1997; 34:275-8. [PMID: 9138148 PMCID: PMC1050911 DOI: 10.1136/jmg.34.4.275] [Citation(s) in RCA: 531] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Haemochromatosis is a genetic disease associated with progressive iron overload, and is common among populations of northern European origin. HLA-H is a recently reported candidate gene for this condition. Two mutations have been identified, a substitution of cysteine for tyrosine at amino acid 282 (C282Y, nucleotide 845) and of histidine for aspartate at amino acid 63 (H63D, nucleotide 187). Over 90% of UK haemochromatosis patients are homozygous for the C282Y mutation. We have examined 5956 chromosomes (2978 people) for the presence of HLA-H C282Y and H63D by PCR followed by restriction enzyme analysis. We have found world wide allele frequencies of 1.9% for C282Y and 8.1% for H63D. The highest frequencies were 10% for C282Y in 90 Irish chromosomes and 30.4% for H63D in 56 Basque chromosomes. C282Y was most frequent in northern European populations and absent from 1042 African chromosomes, 484 Asian chromosomes, and 644 Australasian chromosomes. The distribution of the C282Y mutation coincides with that of populations in which haemochromatosis has been reported and is consistent with the theory of a north European origin for the mutation. The H63D polymorphism is more widely distributed and its connection with haemochromatosis remains unclear.
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46
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Robson KJ, Shearman JD, Merryweather-Clarke AT, Pointon JJ, Rosenberg WM, Walker AP, Dooley JS, Bomford A, Raha-Chowdhury R, Worwood M. Haemochromatosis: a gene at last? J Med Genet 1997; 34:148-51. [PMID: 9039993 PMCID: PMC1050870 DOI: 10.1136/jmg.34.2.148] [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: 02/03/2023]
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47
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Robson KJ, Naitza S, Barker G, Sinden RE, Crisanti A. Cloning and expression of the thrombospondin related adhesive protein gene of Plasmodium berghei. Mol Biochem Parasitol 1997; 84:1-12. [PMID: 9041516 DOI: 10.1016/s0166-6851(96)02774-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Sporozoite recognition of host cells is a key step in the life-cycle of malaria parasites. Two sporozoite proteins have so far been characterized in some detail, the circumsporozoite protein (CS) and thrombospondin related adhesive protein (TRAP). We report here the cloning and expression of the TRAP gene homologue from Plasmodium berghei, PbTRAP. The PbTRAP gene encodes a protein of 606 amino acids having a deduced molecular mass of 66 kDa. The overall structure is clearly that of the TRAP family having a signal sequence followed by an integrin A domain, a sulphatide binding motif, followed by a proline based repeat before a transmembrane domain and helical cytoplasmic tail. The observed molecular mass is almost 50% larger than expected, this can be explained almost entirely by the abnormal behaviour in SDS-PAGE of the proline based repeat. As would be expected PbTRAP shows greatest similarity with the P. yoelli TRAP homologue sporozoite surface protein 2 (SSP2) than with PfTRAP, the TRAP gene from P. falciparum. The pattern of expression is similar to that of SSP2.
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48
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Li JL, Robson KJ, Chen JL, Targett GA, Baker DA. Pfmrk, a MO15-related protein kinase from Plasmodium falciparum. Gene cloning, sequence, stage-specific expression and chromosome localization. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 241:805-13. [PMID: 8944769 DOI: 10.1111/j.1432-1033.1996.00805.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Cyclin-dependent kinases (Cdks) play a central role in the regulation of the eukaryotic cell cycle. A novel gene encoding a Cdk-like protein, Pfmrk, has been isolated from the human malaria parasite Plasmodium falciparum. The gene has no introns and comprises an open reading frame encoding a protein of 324 amino acids with a predicted molecular mass of 38 kDa. Database searches revealed a striking similarity to the Cdk subfamily with the highest similarity to human MO15 (Cdk7). The overall sequence of Pfmrk shares 62% similarity and 46% identity with human MO15, in comparison to the 49-58% similarity and 34-43% identity with other human Cdks. Pfmrk contains two unique inserts: one consisting of 5 amino acids just before the cyclin-binding motif and the other composed of 13 amino acids within the T-loop equivalent region. Southern blots of genomic DNA digests and chromosomal separations showed that Pfmrk is a single-copy gene conserved between several parasite strains and is located on chromosome 10. A 2500-nucleotide transcript of this gene is expressed predominantly in the sexual blood stages (gametocytes), suggesting that Pfmrk may be involved in sexual stage development.
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49
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Robson KJ, Kotre CJ, Faulkner K. An experimental investigation of the effect of light-box luminance on the detection of low contrast objects in mammography. Br J Radiol 1996; 69:153-9. [PMID: 8785644 DOI: 10.1259/0007-1285-69-818-153] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
It has been hypothesized that light-box luminance is an important factor in the detection of objects on radiographs. In this work, existing psychophysical data relating to the measurement of visual thresholds at various scene luminance levels are applied to the problem of the observation of radiographs on a light-box. These data suggest that for a given stimulus size, the threshold contrast varies little over several orders of magnitude of scene luminance. In a series of contrast detail experiments performed over a wide range of light-box luminances it has been demonstrated that the detection of low contrast objects on mammographic film is dominated by external noise, that is noise on the film, rather than the internal visual noise of the observer. It is therefore suggested that in mammography it is inappropriate to base recommendations for optimal values of light-box luminance on psychophysical studies of visual noise. It has been shown that commonly used light-box luminances are suitable for viewing mammograms at the higher average optical densities now being recommended, provided that precautions are taken to avoid glare and reflection.
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Raha-Chowdhury R, Bowen DJ, Stone C, Pointon JJ, Terwilliger JD, Shearman JD, Robson KJ, Bomford A, Worwood M. New polymorphic microsatellite markers place the haemochromatosis gene telomeric to D6S105. Hum Mol Genet 1995; 4:1869-74. [PMID: 8595409 DOI: 10.1093/hmg/4.10.1869] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The haemochromatosis gene (HFE) is linked to both HLA-A and D6S105 on the short arm of chromosome 6 but these markers are separated by approximately 2 Mb of DNA. Most chromosomes carrying HFE have a common haplotype which extends from HLA-A to D6S105 and includes HLA-F. To localise the gene more precisely we have examined 10 microsatellite markers extending over a genetic distance of approximately 5 cM from D6S265 (within 100 kb of HLA-A on the centromeric side) to D6S299 (telomeric). The order of markers is D6S265, HLA-F, D6S258, D6S306, CS3, D6S105, D6S464, CS5, D6S461 and D6S299. We confirm that haemochromatosis appears to originate from a founder mutation which has multiplied in the population through successive generations. This mutation is associated with the haplotype D6S306-5, CS3-3, D6S105-8, D6S464-9 and CS5-4 which is found on approximately 70% of HFE chromosomes. We have applied a new and powerful, likelihood analysis for linkage disequilibrium. The maximum value of lambda (proportion of total possible association between a marker and disease) is 0.74 for marker CS5 (allele 4). A multipoint analysis also gives a maximum likelihood near marker CS5. We conclude that the HFE gene is likely to be located telomeric of D6S105 and close to CS5.
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