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Meier R, Schmitt R, Christopoulos G, Krimmer H. [TFCC-lesion. MR arthrography vs. arthroscopy of the wrist]. Unfallchirurg 2003; 106:190-4. [PMID: 12658336 DOI: 10.1007/s00113-002-0505-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
In a blinded study from January to July 2000, 125 patients suffering from specific complaints of the wrist were examined with direct MR arthrography prospectively. Within 24 hours an arthroscopy of the wrist was performed. With the MR arthrography in 70 patients or 56% of all patients injury of the TFCC was diagnosed. In 65 patients this could be verified arthroscopically. In the remaining 55 patients no TFCC lesion was diagnosed with the MR arthrography. However lesions were found via arthroscopy in three cases,were MRI findings expected an intact TFCC. In the remaining 52 cases the MRT could exclude a lesion of the TFCC correctly. An agreement of the MRT and arthroscopic results could be determined in 93.6% of the cases (correlation). The diagnosis of a TFCC lesion by means of MRI was correct in 94% of the cases (sensitivity), the exclusion of such lesion in 89% (specificity). Positive or negative predictive values of 91% or 93% were achieved. Since neither a specificity nor a sensitivity of 100% can be reached at the moment, the MR arthrography cannot replace the arthroscopy. However it could be a potent additional tool for wrist diagnosis if intraarticular contrast is used. It can facilitate the diagnostics and the indication for surgery at the ulnocarpal wrist and help to reduce arthroscopic interventions that are only for diagnostic purposes and without any therapeutic consequences. With improvement of the technique of magnet resonance tomography we can expect further increase of accuracy and the clinical use of the MR arthrography in the diagnostic workup at the ulnocarpal wrist.
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Meier R, Schmitt R, Christopoulos G, Krimmer H. [Scapholunate ligament tears in MR arthrography compared with wrist arthroscopy]. HANDCHIR MIKROCHIR P 2002; 34:381-5. [PMID: 12601604 DOI: 10.1055/s-2002-37475] [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: 10/27/2022] Open
Abstract
In a blinded study from January to July 2000, 125 patients suffering from specific complaints of the wrist were prospectively examined with direct MR arthrography. Within 24 hours an arthroscopy of the wrist was performed. With MR arthrography in 21 patients or 17 % of all patients, injury of the scapho-lunate ligament was diagnosed. In all patients this could be verified arthroscopically. In the remaining 104 patients, no SL-ligament lesions were diagnosed with the MR arthrography. However, partial lesions were found via arthroscopy in seven cases and complete lesions of the ligament were found in one case, where MRI findings expected an intact SL ligament. In the remaining 96 cases, the MRI could correctly exclude a lesion of the SL-ligament. The diagnosis of a SL-ligament lesion by means of MRI was correct in 100 % of the cases (specificity), the exclusion of such lesions in 72 % (sensitivity). Positive or negative predictive values of 100 % or 92 % were achieved. Since a sensitivity of 100 % cannot be reached at the moment, MR arthrography cannot replace arthroscopy. However, it could be a potent additional tool for wrist diagnosis if intraarticular contrast is used. It can facilitate the diagnostics and the indication for surgery of the wrist and help to reduce arthroscopic interventions for purely diagnostic purposes and without any therapeutic consequences. With improvement of the technique of magnet resonance tomography we can expect a further increase of accuracy in the clinical use of the MR arthrography in the diagnostic workup of the wrist.
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Liakopoulou-Kairis M, Alifieraki T, Protagora D, Korpa T, Kondyli K, Dimosthenous E, Christopoulos G, Kovanis T. Recurrent abdominal pain and headache--psychopathology, life events and family functioning. Eur Child Adolesc Psychiatry 2002; 11:115-22. [PMID: 12369770 DOI: 10.1007/s00787-002-0276-0] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We assessed the psychopathology of children and adolescents with Recurrent Abdominal Pain (RAP) and tension-type headaches (TTH), the psychopathology and Expressed Emotion (EE) of their mothers and family functioning. Additionally, we assessed the relationship of negative Life Events (LE) to RAP and headaches. Sixty-nine children and adolescents with either RAP or headaches, and their mothers were examined and compared to controls. Of the children with RAP or headache, 81.6% and 83.9% respectively carried a psychiatric diagnosis, primarily anxiety or depressive disorder, in contrast to 15% of controls. Mothers of patients with RAP showed more symptoms of anger and hostility than controls. Index mothers had higher EE than control mothers. More problems were reported in the families of patients with RAP. Families of patients with headache were similar to those with RAP but differed from controls in terms of behaviour control and general functioning. More negative LE were experienced by both index groups. If psychological intervention is decided for certain children with RAP or TTH, it should address their depression, anxiety, the impact of negative LE and family functioning.
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Schmitt R, Fröhner S, Brunn J, Müller M, Coblenz G, Fellner F, Christopoulos G, Kerber S. [Multi-slice spiral CT of the coronary arteries: clear vascular imaging using standard software]. RONTGENPRAXIS; ZEITSCHRIFT FUR RADIOLOGISCHE TECHNIK 2002; 54:127-40. [PMID: 11883116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
OBJECTIVE To visualize the coronary arteries with a clear view and over a long distance by using data sets from contrast-enhanced computed tomography of the heart. MATERIAL AND METHODS Image data of 151 patients suffering from coronary artery disease were calculated by means of retrospective triggering at four different diastolic delay times in contrast-enhanced CT. The large coronary segments were subsequently reconstructed in two planes with multiplanar volume reconstruction (MPVR)--a non-dedicated postprocessing software. RESULTS On the pre-condition that data sets were acquired at sinus rhythm and at a heart beat rate lower than 65/min coronary arteries could be depicted over a long distance in single or double angulated reconstruction planes with the help of multiplanar volume reconstruction (MPVR). Time consumption for image reconstruction was reasonable. Additionally to the anatomy of the coronary arteries in two different planes, typical CT findings in occluding coronary artery disease are presented. CONCLUSION Multiplanar volume reconstruction (MPVR) implemented on most workstations is a powerful and ideal postprocessing tool in reconstructing coronary arteries from contrast-enhanced CT data sets.
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Schmitt R, Christopoulos G, Brunner S, Fröhner S, Dobritz M, Fellner F. [MR angiography of pelvic and leg arteries: initiation with time-resolved data acquisition of the lower legs]. RONTGENPRAXIS; ZEITSCHRIFT FUR RADIOLOGISCHE TECHNIK 2002; 54:83-92. [PMID: 11799869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
58 patients suffering from peripheral arterial vascular disease were examined using contrast-enhanced MR angiography with the intention of optimizing the visualization of lower leg arteries. Different from the customary acquisition order, were first the arteries of the lower legs depicted with three time-resolved phases. Afterwards, the iliacal and femoral vessels were imaged by applying the floating-table technique in two steps. In all cases, the lower leg arteries were depicted without overlying veins. By injecting the contrast agent in two phases, imaging quality of the iliofemoral arteries was not significantly reduced.--In conclusion, we would recommend the hybrid technique of peripheral contrast-enhanced MRA with primarily starting the acquisition of the lower legs in cases of foot infections or ulcerations where the transit time is reduced bi- or unilaterally.
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Schmitt R, Christopoulos G, Fröhner S, Binder F, Schweiger H. [Diagnosis of rare diseases of the popliteal artery]. RONTGENPRAXIS; ZEITSCHRIFT FUR RADIOLOGISCHE TECHNIK 2002; 54:4-13. [PMID: 11582989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
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Kyrri A, Felekis X, Kalogerou E, Christopoulos G, Makariou C, Loizidou D, Kleanthous M. Hb Limassol [beta8(A5)Lys-->Asn]: a new hemoglobin variant. Hemoglobin 2001; 25:421-4. [PMID: 11791876 DOI: 10.1081/hem-100107880] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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58
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von Gossler C, Kall S, Christopoulos G, Prommersberger KJ. [Melorheostosis of the hand. A case report]. HANDCHIR MIKROCHIR P 2001; 33:328-31. [PMID: 11600949 DOI: 10.1055/s-2001-17767] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022] Open
Abstract
Summary. Melorheostosis is a sclerosing disease commonly affecting the bone, rarely soft tissue. Etiology is unknown. It causes uncharacteristic symptoms such as pain, joint stiffness, soft tissue contractures, and limb deformities. Standard radiology reveals the diagnosis. Until now there is no standard therapy. Melorheostosis is a rare bone dysplasia and important as a differential diagnosis for tumorous changes in the limb or in painful joints.
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Choulakis M, Kastanioudakis I, Koudoumnakis E, Ziavra N, Christopoulos G, Skevas A. Huge nasopharyngeal true teratoma with cleft palate and lip and unilateral choanal atresia. Otolaryngol Head Neck Surg 2001; 124:584-5. [PMID: 11337670 DOI: 10.1067/mhn.2001.115369] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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60
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Feleki X, Najmabadi H, Karimi-Nejad R, Christopoulos G, Kleanthous M. Identification of a novel beta0-thalassemia mutation, codons 80/81 (-C), in an Iranian family. Hemoglobin 2000; 24:319-21. [PMID: 11186262 DOI: 10.3109/03630260008993139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Tilakaratne N, Christopoulos G, Zumpe ET, Foord SM, Sexton PM. Amylin receptor phenotypes derived from human calcitonin receptor/RAMP coexpression exhibit pharmacological differences dependent on receptor isoform and host cell environment. J Pharmacol Exp Ther 2000; 294:61-72. [PMID: 10871296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023] Open
Abstract
Receptor activity modifying proteins (RAMPs) constitute a group of three proteins, designated as RAMP1, 2, and 3, which are able to effect functional changes in some members of the G protein-coupled receptor family. Thus, RAMP1 or RAMP3 can modify the calcitonin receptor (CTR) to also function as a high-affinity amylin receptor-like phenotype. To examine the RAMP/CTR interaction, individual RAMPs were coexpressed with either of the two human CTR (hCTR) isoforms, the insert negative (hCTR(I1-)) or the insert positive (hCTR(I1+)), in Chinese hamster ovary (CHO-P) or African monkey kidney (COS-7) cells. CHO-P cells provide an environment conducive to a low, but significant, level of amylin binding with either hCTR isoform alone, unlike in COS-7, where RAMP coexpression is imperative for amylin binding. Also, in CHO-P, hCTR(I1-) induced amylin binding with all three RAMPs, in contrast to COS-7, where only RAMP1 or RAMP3 generate an amylin receptor phenotype. hCTR(I1+) induced high-affinity amylin binding with any RAMP in either cell line. In COS-7 cells, hCTR(I1+)/RAMP-generated receptor displayed high- and low-affinity states, in contrast with the single-state binding seen with hCTR(I1-)/RAMP-generated receptor, whereas in CHO-P cells a two-affinity state receptor phenotype was evident with both hCTR isoforms. Endogenous RAMP expression is low and similar between cell lines. The results suggest that CTR/RAMP interaction in these cells is complex with other cellular factors such as the levels of different G proteins and/or receptor/RAMP stoichiometry following heterologous coexpression contributing to the ultimate receptor phenotype.
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Drousiotou A, Stylianidou G, Anastasiadou V, Christopoulos G, Mavrikiou E, Georgiou T, Kalakoutis G, Oladimeji A, Hara Y, Suzuki K, Furihata K, Ueno I, Ioannou PA, Fensom AH. Sandhoff disease in Cyprus: population screening by biochemical and DNA analysis indicates a high frequency of carriers in the Maronite community. Hum Genet 2000; 107:12-7. [PMID: 10982028 DOI: 10.1007/s004390000324] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
In the last 15 years, four patients with the infantile form of Sandhoff disease were diagnosed in four different families in Cyprus (population 703,000, birth rate 1.7%). Three of these cases came from the Christian Maronite community (less than 1% of the population) and one from the Greek community (84% of the population). This relatively large number of patients prompted us to initiate an epidemiological study in order to establish the frequency of the mutant allele in Cyprus. Carrier detection was initially based on the measurement of beta-hexosaminidase A and B in both leucocytes and serum. Using the enzyme test, 35 carriers were identified among 244 random Maronite samples and 15 among 28 Maronites with a family history of Sandhoff disease, but only one carrier was found out of 115 random samples from the Greek community. In parallel to the biochemical screening, DNA studies were undertaken in one of the three Maronite patients and in a Greek carrier related to the Greek patient. These studies resulted in the identification of two novel mutations, a deletion of A at nt76 and a G to C transversion at position 5 of the 5'-splice site of intron 8, which have been published. We subsequently screened the carriers detected in the biochemical study for these two mutations using PCR-based tests. Of 50 Maronite carriers examined, 42 were found to have the nt76 deletion. Eight Maronite samples, designated carriers from the biochemical results, were negative for both mutations. It is possible that these individuals were incorrectly classified as carriers since their enzyme values are equivocal, although the presence of another mutation has not been excluded. Two Greek Cypriot carriers and two obligate Lebanese carriers were negative for both mutations. We conclude that there is a high frequency of Sandhoff disease carriers in the Maronite community of Cyprus, approximately 1 in 7, and that a single mutation predominates in this population.
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Furihata K, Drousiotou A, Hara Y, Christopoulos G, Stylianidou G, Anastasiadou V, Ueno I, Ioannou P. Novel splice site mutation at IVS8 nt 5 of HEXB responsible for a Greek-Cypriot case of Sandhoff disease. Hum Mutat 2000; 13:38-43. [PMID: 9888387 DOI: 10.1002/(sici)1098-1004(1999)13:1<38::aid-humu4>3.0.co;2-s] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Sandhoff disease is caused by abnormalities in HEXB gene encoding the beta-subunit of beta-hexosaminidase. In this study, we analyzed the HEXB gene of a Sandhoff carrier in the Greek-Cypriot community. A G to C transversion was identified in one allele of her HEXB gene at position 5 of the 5'-splice site of intron 8 (IVS8 nt5). One of 13 cDNA clones derived from her lymphocyte HEXB mRNA lacked the last four nucleotides "GTTG" of exon 8, which created a premature termination codon at 11 codons downstream. In vivo transcription of the mutant HEXB gene fragment in CHO cells resulted in deletion of the "GTTG." The mutation has not been found in 40 DNA samples from anonymous donors, indicating that this is not a polymorphism in the Cypriot population. These results clearly indicate that the splice site mutation at IVS8 nt5 is responsible for this case of Sandhoff disease.
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Kyriacou K, Al Quobaili F, Pavlou E, Christopoulos G, Ioannou P, Kleanthous M. Molecular characterization of beta-thalassemia in Syria. Hemoglobin 2000; 24:1-13. [PMID: 10722110 DOI: 10.3109/03630260009002268] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
This study concerns the determination of beta-thalassemia alleles and other hemoglobin variants in 82 patients from Syria. We have characterized 146 chromosomes and found 17 different beta-thalassemia mutations, and one beta-globin chain variant that gives rise to the abnormal Hb S. The eight most common beta-thalassemia mutations were the IVS-I-110 (G-->A), IVS-I-1 (G-->A), codon 5 (-CT), -30 (T-->A), codon 39 (C-->T), IVS-I-6 (T-->C), IVS-II-1 (G-->A), and codon 15 (TGG-->TAG). These mutations accounted for almost 75% of the total beta-thalassemia chromosomes. We identified 34 different genotypes with a high level of homozygosity. The various beta-thalassemia mutations were characterized using gene amplification with specific oligonucleotide primers, restriction enzyme analysis, denaturing gradient gel electrophoresis and direct sequencing. By combining these three approaches we were able to detect mutations in almost 90% of the chromosomes studied. Our findings provide a sound foundation on which to base a preventive program for thalassemia and we believe that the data that we present will facilitate the improvement of medical services such as carrier screening, genetic counseling, and prenatal diagnosis. Furthermore a detailed knowledge of the molecular pathology of beta-thalassemia will strongly improve the prenatal diagnosis services in Syria.
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Zumpe ET, Tilakaratne N, Fraser NJ, Christopoulos G, Foord SM, Sexton PM. Multiple ramp domains are required for generation of amylin receptor phenotype from the calcitonin receptor gene product. Biochem Biophys Res Commun 2000; 267:368-72. [PMID: 10623626 DOI: 10.1006/bbrc.1999.1943] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Calcitonin (CT), calcitonin gene-related peptide (CGRP), amylin, and adrenomedullin constitute a family of structurally related peptides that signal via either the calcitonin receptor-like receptor or the CT receptor, with receptor phenotype determined by coexpression of one of the three receptor activity-modifying proteins (RAMPs). The nature of the interaction between the receptor and RAMP was investigated using chimeras between RAMP1 and RAMP2 where the amino-terminal domain of RAMP1 was attached to the transmembrane domain and carboxy terminus of RAMP2 and called RAMP1/2, and vice versa for RAMP2/1. Cotransfection of wild-type or chimeric RAMPs with the insert-negative isoform of the human CT receptor (hCTR(I1-)) into COS-7 cells resulted in the expression of (125)I-rat amylin binding sites. Highest specific binding was observed when either RAMP1 or RAMP2/1 were cotransfected, indicating the importance of the RAMP transmembrane domain and/or carboxy terminus for the degree to which amylin receptors are expressed. In contrast, the phenotype generated was primarily determined by the amino terminus, with similar RAMP1- and RAMP1/2-induced receptor phenotypes that had higher affinity for human CGRPalpha and lower affinity for human calcitonin than the RAMP2- and RAMP2/1-induced receptors.
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Drousiotou A, Ioannou P, Georgiou T, Mavrikiou E, Christopoulos G, Kyriakides T, Voyasianos M, Argyriou A, Middleton L. Neonatal screening for Duchenne muscular dystrophy: a novel semiquantitative application of the bioluminescence test for creatine kinase in a pilot national program in Cyprus. GENETIC TESTING 1999; 2:55-60. [PMID: 10464597 DOI: 10.1089/gte.1998.2.55] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The objectives of this study were to evaluate a novel semiquantitative application of the bioluminescence test for screening newborns for Duchenne muscular dystrophy (DMD) and to use this technique in a pilot national program. The study was performed on the island of Cyprus, which provides ideal conditions for maximizing the prevention rate due to the small size of the country, the well-defined population, and the high degree of awareness of the public concerning genetic diseases. Guthrie spots were obtained through the national screening center for phenylketonuria and congenital hypothyroidism. The bioluminescence method for measuring creatine kinase (CK) in dried blood spots was adapted for use in a semiquantitative way. During the first 6 years of the program (1992-1997), we screened 30,014 samples and found 43 with initially high CK values. We were able to obtain repeat specimens in 35 cases. Of the repeat samples, 30 were found to have normal activity, giving a false-positive rate of 0.10%. Five boys had persistent CK elevations and were confirmed to be DMD or Becker (BMD) cases by DNA analysis and/or dystrophin analysis. The semiquantitative application of the bioluminescence assay of CK that we have introduced has proved to be a fast and reliable method for screening large numbers of samples for DMD. It has a low rate of false positives, which compares favorably with that of other DMD screening programs. Although it is early to evaluate its impact fully, the program seems to be bringing about the anticipated benefits to affected families.
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Christopoulos G, Perry KJ, Morfis M, Tilakaratne N, Gao Y, Fraser NJ, Main MJ, Foord SM, Sexton PM. Multiple amylin receptors arise from receptor activity-modifying protein interaction with the calcitonin receptor gene product. Mol Pharmacol 1999; 56:235-42. [PMID: 10385705 DOI: 10.1124/mol.56.1.235] [Citation(s) in RCA: 366] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Receptor activity-modifying proteins (RAMPs) are single-transmembrane proteins that transport the calcitonin receptor-like receptor (CRLR) to the cell surface. RAMP 1-transported CRLR is a calcitonin gene-related peptide (CGRP) receptor. RAMP 2- or RAMP 3-transported CRLR is an adrenomedullin receptor. The role of RAMPs beyond their interaction with CRLR, a class II G protein-coupled receptor, is unclear. In this study, we have examined the role of RAMPs in generating amylin receptor phenotypes from the calcitonin (CT) receptor gene product. Cotransfection of RAMP 1 or RAMP 3 with the human CT receptor lacking the 16-amino acid insert in intracellular domain 1 (hCTRI1-) into COS-7 cells induced specific 125I-labeled rat amylin binding. RAMP 2 or vector cotransfection did not cause significant increases in specific amylin binding. Competition-binding characterization of the RAMP-induced amylin receptors revealed two distinct phenotypes. The RAMP 1-derived amylin receptor demonstrated the highest affinity for salmon CT (IC50, 3.01 +/- 1.44 x 10(-10) M), a high to moderate affinity for rat amylin (IC50, 7.86 +/- 4.49 x 10(-9) M) and human CGRPalpha (IC50, 2.09 +/- 1.63 x 10(-8) M), and a low affinity for human CT (IC50, 4.47 +/- 0.78 x 10(-7) M). In contrast, whereas affinities for amylin and the CTs were similar for the RAMP 3-derived receptor, the efficacy of human CGRPalpha was markedly reduced (IC50, 1.12 +/- 0.45 x 10(-7) M; P <.05 versus RAMP 1). Functional cyclic AMP responses in COS-7 cells cotransfected with individual RAMPs and hCTRI1- were reflective of the phenotypes seen in competition for amylin binding. Confocal microscopic localization of c-myc-tagged RAMP 1 indicated that, when transfected alone, RAMP 1 almost exclusively was located intracellularly. Cotransfection with calcitonin receptor (CTR)I1- induced cell surface expression of RAMP 1. The results of experiments cross-linking 125I-labeled amylin to RAMP 1/hCTR-transfected cells with bis succidimidyl suberate were suggestive of a cell-surface association of RAMP 1 and the receptors. Our data suggest that in the CT family of receptors, and potentially in other class II G protein-coupled receptors, the cellular phenotype is likely to be dynamic in regard to the level and combination of both the receptor and the RAMP proteins.
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Chai SY, Christopoulos G, Cooper ME, Sexton PM. Characterization of binding sites for amylin, calcitonin, and CGRP in primate kidney. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:F51-62. [PMID: 9458823 DOI: 10.1152/ajprenal.1998.274.1.f51] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Analysis of receptor distributions for 125I-labeled amylin, 125I-labeled calcitonin, and 125I-labeled calcitonin gene-related peptide (CGRP) in Macaca fascicularis kidney by in vitro autoradiography revealed distinct patterns of binding for each peptide. 125I-rat amylin bound primarily to the cortex, being associated with the distal tubule, including apparent binding to the juxtaglomerular apparatus. 125I-salmon calcitonin displayed high-density binding in the cortex with low-density binding to the medulla. Emulsion autoradiography indicated that binding was associated with both distal tubule and thick ascending limb of the loop of Henle. Intense binding was also found often over juxtaglomerular apparatus. 125I-rat CGRP-alpha exhibited low- to moderate-density binding to the inner medulla/papilla with high-density binding over small-, medium-, and large-caliber arteries. Weak binding to the glomerulus was also seen, but no binding was associated with cortical tubules. Competition binding studies, performed with each of the radioligands, revealed peptide specificity profiles for CGRP and calcitonin receptors that were similar to those described in rat. However, the monkey amylin receptors differed from those in rat, exhibiting relatively higher affinity for calcitonin peptides but reduced affinity for CGRP peptides. These studies suggest potential roles for amylin, calcitonin, and CGRP in primate renal function.
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Perry KJ, Quiza M, Myers DE, Morfis M, Christopoulos G, Sexton PM. Characterization of amylin and calcitonin receptor binding in the mouse alpha-thyroid-stimulating hormone thyrotroph cell line. Endocrinology 1997; 138:3486-96. [PMID: 9231803 DOI: 10.1210/endo.138.8.5312] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Recently, a high affinity amylin binding site was identified in the mouse alpha-TSH thyrotroph cell line. In this study, we have characterized binding sites for 125I-salmon calcitonin (125I-sCT), 125I-rat alpha-calcitonin gene-related peptide (125I-CGRP), and 125I-rat amylin in alpha-TSH cells. Using 125I-CGRP or 125I-rat amylin, equilibrium was rapidly reached, and binding was fully reversible. Competition binding revealed the relative potency of peptides was sCT>amylin, CGRP>>rCT, which is similar to the specificity profile of amylin receptors characterized in rat brain. Furthermore, specific binding of 125I-rat amylin and 125I-CGRP to membrane preparations was reduced by 52% and 39%, respectively, in the presence of 20 microM GTP-gamma-s, indicating a requirement of G protein coupling for high affinity binding. In contrast, 125I-sCT binding reached equilibrium more slowly, was essentially irreversible, and was unaltered by GTP-gamma-s. Competition binding studies using 125I-sCT as radioligand demonstrated only weak interaction by CGRP or amylin, consistent with other described CT receptors. Assessment of ligand-induced cAMP accumulation and intracellular calcium signaling revealed a relative specificity profile of sCT>rCT with little or no second messenger signaling stimulated by amylin or CGRP, consistent with a C1-CT receptor phenotype. RT-PCR amplification of messenger RNA indicated that the predominant isoform was the C1a CT receptor. In cross-linking studies, 125I-rat amylin and 125I-CGRP specifically labeled a major band of relative molecular mass (Mr) approximately 80K, being approximately 10 kDa higher than the major 125I-sCT binding protein. Full deglycosylation of N-linked carbohydrates with endoglycosidase F reduced the Mr of each of the labeled proteins to approximately 50K. Cross-linked amylin or CT receptors were immunoprecipitated with C-terminally directed antimouse or antirat CT receptor antibodies but were not immunoprecipitated with nonimmune sera or antihuman CT receptor antibodies. The current data demonstrate expression of two biochemically distinct receptor phenotypes in mouse alpha-TSH cells, a CT receptor phenotype and an amylin receptor phenotype that have highly similar protein backbones.
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MESH Headings
- Amino Acid Sequence
- Amyloid/metabolism
- Animals
- Base Sequence
- Binding, Competitive
- Blotting, Southern
- Blotting, Western
- Calcitonin Gene-Related Peptide/analysis
- Calcitonin Gene-Related Peptide/metabolism
- Chromatography, High Pressure Liquid
- Cyclic AMP/metabolism
- Glycoprotein Hormones, alpha Subunit/analysis
- Guanosine 5'-O-(3-Thiotriphosphate)/pharmacology
- Iodine Radioisotopes
- Islet Amyloid Polypeptide
- Mice
- Molecular Sequence Data
- Phenotype
- Polymerase Chain Reaction
- Precipitin Tests
- Protein Binding
- RNA, Messenger/analysis
- RNA, Messenger/chemistry
- RNA, Messenger/genetics
- Rats
- Receptors, Calcitonin/analysis
- Receptors, Calcitonin/genetics
- Receptors, Calcitonin/metabolism
- Receptors, Islet Amyloid Polypeptide
- Receptors, Peptide/analysis
- Receptors, Peptide/genetics
- Receptors, Peptide/metabolism
- Thyroid Neoplasms/chemistry
- Thyroid Neoplasms/metabolism
- Thyroid Neoplasms/pathology
- Time Factors
- Tumor Cells, Cultured
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70
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Findlay DM, Houssami S, Christopoulos G, Sexton PM. Homologous regulation of the rat C1a calcitonin receptor (CTR) in nonosteoclastic cells is independent of CTR messenger ribonucleic acid changes and cyclic adenosine 3',5'-monophosphate-dependent protein kinase activation. Endocrinology 1996; 137:4576-85. [PMID: 8895320 DOI: 10.1210/endo.137.11.8895320] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
UMR106-06 cells predominantly express the C1a isoform of the rat calcitonin (CT) receptor (CTR). We have compared the homologous regulation of the C1a CTR endogenously expressed in UMR106-06 cells with the cloned C1a CTR in transfected HEK 293 cells, in which expression is driven by a heterologous promoter. It was found that treatment of both cell lines with either salmon CT or human CT reduced the density of cell surface CTR in a dose- and time-dependent manner. However, the magnitude of the response was greater in UMR106-06 cells, and salmon CT was more potent than human CT in both cell lines. Recovery from down-regulation was rapid in transfected cells (< 2 h), but was comparatively delayed in UMR106-06 cells, where less than 70% of receptor-binding capacity had returned by 24 h. In both cell lines, treatment with either agonist increased the basal activity of CT-sensitive adenylate cyclase and caused a time-dependent reduction in the responsiveness of adenylate cyclase to a second challenge with CT. Reduced responsiveness occurred under conditions of minimal loss of CTR from the cell surface, consistent with an uncoupling of the receptor from the signal transduction apparatus. Recovery of CT-sensitive adenylate cyclase was complete in transfected cells by 24 h, but was delayed in UMR106-06 cells, paralleling the slow recovery of receptor binding. CT-induced down-regulation of the CTR was not mimicked by receptor-independent activation of protein kinase A or protein kinase C. However, treatment of cells for 24 h, but not for 4 h, with phorbol ester caused a partial loss of CTR binding in UMR106-06 cells and resulted in an approximately 200% increase in CTR binding in transfected HEK 293 cells. CTR messenger RNA levels, as assessed by reverse transcription-PCR, were not changed by any of the above treatments. These results suggest that CT-induced receptor down-regulation and modulation of the ability of CT to activate adenylate cyclase are inherent properties of the receptor, as they can be recapitulated in an otherwise CTR-naive cell line, in which receptor expression is driven by a heterologous gene promoter. Moreover, and in contrast with CTR regulation in osteoclasts, activation of protein kinase A is insufficient for ligand-induced regulation of the CTR in these nonosteoclastic cell lines, and receptor regulation does not appear to involve altered messenger RNA levels.
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71
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Vaiopoulos G, Stamatelos G, Aessopos A, Michael S, Christopoulos G, Kaklamanis PH. Asymptomatic pericarditis in Adamantiadis-Behçet's disease. Clin Exp Rheumatol 1995; 13:649-51. [PMID: 8575147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Pericardial involvement in Adamantiadis-Behçet's disease (ABD) is uncommon. A 14-year-old boy presented with fever of unknown origin, as the initial and only manifestation of his disease. Other features were leukopenia, abdominal lymphadenopathy and asymptomatic pericarditis, which is a very rare finding of the disease. A review of pericarditis is presented.
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72
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Christopoulos G, Paxinos G, Huang XF, Beaumont K, Toga AW, Sexton PM. Comparative distribution of receptors for amylin and the related peptides calcitonin gene related peptide and calcitonin in rat and monkey brain. Can J Physiol Pharmacol 1995; 73:1037-41. [PMID: 8846397 DOI: 10.1139/y95-146] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The distribution of amylin receptors (125I-labelled rat amylin) in brains of rat and monkey were mapped and compared with the distribution of receptors for calcitonin (CT) (125I-labelled salmon CT) and calcitonin gene related peptide (CGRP) (rat, 125I-labelled rat CGRP alpha; monkey, 125I-labelled human CGRP alpha. In rat, amylin receptors were discretely distributed with the highest receptor densities found in mid-caudal accumbens nucleus, parts of the bed nucleus of the stria terminalis, amygdala, and hypothalamus. Moderate to high densities of binding also occurred in the area postrema, subfornical organ, vascular organ of the lamina terminalis, locus ceruleus, dorsal raphe, and caudal solitary tract nucleus. In monkey, the distribution of amylin binding sites was similar, although the highest densities of receptors were in the hypothalamus, with relatively fewer sites present in the accumbens nucleus. In rat, the distribution of amylin receptors formed a subset of the receptor distributions for 125I-labelled salmon CT and 125I-labelled rat CGRP alpha. In contrast, in monkey, although the amylin receptors again formed a subset of the binding sites identified with 125I-labelled salmon CT, there was very little overlap with the pattern of CGRP receptor distribution. This suggests that the specificity profile of amylin receptors in primates differs from that of amylin receptors in the rat, with CGRP alpha having relatively lower affinity for the primate amylin receptors.
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73
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Petridou E, Zervos I, Christopoulos G, Revinthi K, Papoutsakis G, Trichopoulos D. Biosocial variables and auditory acuity as risk factors for non-fatal childhood injuries in Greece. Inj Prev 1995; 1:92-6. [PMID: 9346003 PMCID: PMC1067559 DOI: 10.1136/ip.1.2.92] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
OBJECTIVES To examine whether biosocial variables and auditory acuity are risk factors for injuries among children. SETTING Children with injuries who presented at the emergency clinics of one of the two university hospitals for children in Athens, Greece between December 1993 and April 1994. METHODS 144 children aged 5-14 years, residents of Athens, were brought to the emergency clinics for a moderate to severe injury. For each of these children one hospital control, matched for age and sex, and one classmate control similarly matched were identified. A standard interview form was completed for all 432 children and acouometric and tympanometric examinations were performed in each of them. Analysis was done through conditional logistic regression. RESULTS The likelihood of an accident was higher in children of younger fathers (odds ratio (OR) = 0.7, p = 0.04), children of mothers with non-professional jobs (OR = 1.9, p = 0.03) as well as in children of higher birth order (OR = 1.7, p = 0.01), in those with predominantly other than parental daily supervision (OR = 2.6, p = 0.001), and those with a history of previous accident (OR = 1.3, p = 0.002). Somatometric factors, school performance, use of corrective eyeglasses and subnormal auditory acuity were not found to be risk factors, but auditory imbalance and abnormal tympanograms were positively related to the risk of childhood injury (OR = 2.6, p = 0.02; and OR = 2.3, p = 0.08 respectively). CONCLUSIONS the findings of this study underline the importance of attentive supervision and safety training of children living in modern cities; they also suggest that children with auditory imbalance and history of an accident are at higher injury risk and they should be targeted with specific intervention programs.
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74
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Ioannou P, Christopoulos G, Panayides K, Kleanthous M, Middleton L. Detection of Duchenne and Becker muscular dystrophy carriers by quantitative multiplex polymerase chain reaction analysis. Neurology 1992; 42:1783-90. [PMID: 1513470 DOI: 10.1212/wnl.42.9.1783] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
We developed a method for the detection of Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) carriers. The method is based on the quantitative analysis of the products of standard multiplex polymerase chain reaction (PCR) from 18 different exons of the dystrophin gene, and is designated "QM-PCR." We detected deletions of one or more exons by standard multiplex PCR in DMD/BMD patients in 14 of 18 families examined (77.7%). The same deletions were readily demonstrated by QM-PCR in nine of 14 mothers (64.3%) and in another six of 22 possible carriers in these families. In five families where deletions were detectable in DMD/BMD patients, the mothers did not exhibit any deletions in their peripheral blood (35.7%). We obtained evidence for germinal mosaicism in at least two of these families and confirmed carrier identification by haplotype analysis using CA repeat polymorphisms at the 5' and 3' ends of the dystrophin gene. Furthermore, analysis of 17 coded DNA samples from normal females and obligatory carriers by QM-PCR showed that this technique could directly identify carriers of deletions in any of 18 different exons of the dystrophin gene. Its application in combination with existing techniques is expected to significantly improve the accuracy of carrier diagnosis in many families, and it may also be applicable to families in which pedigree and polymorphism information is insufficient for carrier diagnosis.
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75
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Christopoulos G, Kirch ER, Gearien JE. Determination of ethanol in fresh and putrefied post mortem tissues. J Chromatogr A 1973; 87:454-72. [PMID: 4765843 DOI: 10.1016/s0021-9673(01)91748-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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