Retinitis pigmentosa and mutations in rhodopsin.
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Base Sequence↗
Biomedical subjects
R Bashir
Publications and source records attributed to R Bashir.
Investigation of the role of polymorphisms at the alcohol and aldehyde dehydrogenase loci in genetic predisposition to alcohol-related end-organ damage.
Little is known about factors determining individual susceptibility to the physical complications of alcohol abuse but genetically determined differences in ethanol metabolism may be important. The oxidative metabolism of alcohol is catalyzed by alcohol and aldehyde dehydrogenase. Polymorphisms have been observed at two of the five loci encoding alcohol dehydrogenase subunits: ADH2 (producing three beta subunits) and ADH3 (producing two tau subunits) and also at the locus encoding the metabolically important form of aldehyde dehydrogenase, ALDH2. We have compared ADH2, ADH3 and ALDH2 allele frequencies in patients with alcohol-related cirrhosis (n = 59) and chronic pancreatitis (n = 13) with 79 local healthy control subjects. The different alleles were detected with allele-specific oligonucleotide probes after amplification of leukocyte DNA by the polymerase chain reaction. All patients and all but one control subject were homozygous ADH2*1, encoding the beta 1 subunit. No ADH2*3 alleles were detected. All 34 patients and 39 control subjects tested were homozygous ALDH2*1 encoding the active enzyme. ADH3 allele frequencies were different in patients and control subjects. ADH3*1 frequency: control subjects, 55.1%; cirrhotic patients, 62.7%; chronic pancreatitis patients, 65.4%. The difference between the patient groups combined and the control subjects was significant (p less than 0.05; G-test of Sokal and Rohlf) if it was assumed that the allele frequency in our control population was a reasonable estimate of our local population allele frequency. These results suggest that genetically determined differences in alcohol metabolism may, in part, explain predisposition to alcohol-related end-organ damage.
Alcohol Dehydrogenase↗
Autosomal dominant retinitis pigmentosa: four new mutations in rhodopsin, one of them in the retinal attachment site.
Several mutations in the rhodopsin gene in patients affected by autosomal dominant retinitis pigmentosa (ADRP) have recently been described. We report four new rhodopsin mutations in ADRP families, initially identified as hetero-duplexed PCR fragments on hydrolink gels. One is an in-frame 12-bp deletion of codons 68 to 71. The other three are point mutations involving codons 190, 211, and 296. Each alters the amino acid encoded. The codon 190 mutation has been detected in 2 from a panel of 34 ADRP families, while the remaining mutations were seen in single families. This suggests that, consistent with a dominant condition, no single mutation will account for a large fraction of ADRP cases. The base substitution in codon 296 alters the lysine residue that functions as the attachment site for 11-cis-retinal, mutating it to glutamic acid. This mutation occurs in a family with an unusually severe phenotype, resulting in early onset of disease and cataracts in the third or fourth decade of life. This result demonstrates a correlation between the location of the mutation and the severity of phenotype in rhodopsin RP.
Amino Acid Sequence↗
Epstein-Barr viral genome in lymph nodes from patients with Hodgkin's disease may not be specific to Reed-Sternberg cells.
A possible etiologic role for Epstein-Barr virus (EBV) in Hodgkin's disease (HD) was investigated by probing for EBV genome in 52 biopsy specimens involved with HD and 43 hyperplastic lymph node specimens. Using dot-blot hybridization (Bam HIW probe), Southern blot hybridization (Xho I probe), and polymerase chain reaction analyses, 27%, 27%, and 58% of the nodes with HD were positive for EBV genome, respectively, as compared to 16%, 14%, and 43% in the hyperplastic lymph nodes. Clonal and nonclonal episomal EBV and linear replicating EBV genome were present in both conditions. Immunoglobulin heavy chain gene rearrangements were found in two clonal and two nonclonal EBV-positive HD cases, but not in the lymphoid hyperplasia cases. These findings and other recent reports showing EBV genome in benign lymphoid cells by in situ hybridization in Hodgkin's disease suggest that the characteristics of EBV infection in HD could be explained by the reactive cellular milieu, especially in the setting of defective immunity. The identification of EBV genome in Reed-Sternberg cells may, therefore, be a nonspecific phenomenon.
Gene Rearrangement↗
SCID/human mouse model of central nervous system lymphoproliferative disease.
Epstein-Barr virus (EBV) carrying malignant lymphomas of the central nervous system are increasing owing to the increasing numbers of immunodeficient patients. To further understand the pathogenesis of these tumors, we studied the invasiveness of four EBV-immortalized lymphoblastoid cell lines in the brains of immunodeficient mice and the expression of adhesion molecules during this process. We injected four EBV-infected human lymphoblastoid cell lines intracerebrally into nude as well as SCID/SCID CB17 mice. Within 13 to 14 days, lethal brain lymphoproliferative lesions resulted in SCID mice, whereas similar lesions developed in 21 to 24 days in nude mice. Atypical large lymphoid cells aggressively infiltrated brain parenchyma, ventricular, and subarachnoid spaces. No difference in invasiveness was found between the monoclonal lymphoblastoid cell lines grown in long-term culture and polyclonal lymphoblastoid cell lines grown for a shorter duration. Tumors retained the same human immunoglobulin expression and activation antigen profile as the original cell lines. Furthermore, tumors expressed human LFA-1/ICAM-1 and the tumor blood vessels strongly expressed murine ICAM-1, but not MECA 79. Mice injected intracerebrally with peripheral blood leukocytes or normal bone marrow cells from an EBV seronegative individual failed to form tumors confirming the pivotal role for EBV in this process. SCID mice offer advantages for studying central nervous system lymphoproliferative disease.
Animals↗
A 3-bp deletion in the rhodopsin gene in a family with autosomal dominant retinitis pigmentosa.
Autosomal dominant retinitis pigmentosa (ADRP) has recently been linked to locus D3S47 (probe C17), with no recombination, in a single large Irish family. Other ADRP pedigrees have shown linkage at zero recombination, linkage with recombination, and no linkage, demonstrating genetic heterogeneity. The gene encoding rhodopsin, the rod photoreceptor pigment, is closely linked to locus D3S47 on chromosome 3q. A point mutation changing a conserved proline to histidine in the 23d codon of the gene has been demonstrated in affected members of one ADRP family and in 17 of 148 unrelated ADRP patients. We have sequenced the rhodopsin gene in a C17-linked ADRP family and have identified in the 4th exon and in-frame 3-bp deletion which deletes one of the two isoleucine monomers at codons 255 and 256. This mutation was not found in 30 other unrelated ADRP families. The deletion has arisen in the sequence TCATCATCAT, deleting one of a run of three x 3-bp repeats. The mechanism by which this occurred may be similar to that which creates length variation in so-called mini- and microsatellites. Thus ADRP is an extremely heterogeneous disorder which can result from a range of defects in rhodopsin and which can have a locus or loci elsewhere in the genome.
Amino Acid Sequence↗
No evidence for linkage between late onset autosomal dominant retinitis pigmentosa and chromosome 3 locus D3S47 (C17): evidence for genetic heterogeneity.
Retinitis pigmentosa is an inherited form of blindness caused by progressive retinal degeneration. P. McWilliam et al. (1989, Genomics 5: 619-622) demonstrated close genetic linkage between autosomal dominant retinitis pigmentosa (ADRP) and locus D3S47 (C17) in a single early onset pedigree. The marker C17 maps to the long arm of chromosome 3. Clinically, the disease phenotype has been subdivided into at least two forms on the basis of age of onset, as well as electrodiagnostic criteria. We demonstrate that C17 is unlinked in a late onset pedigree, indicating that the phenotypic variation seen reflects underlying genetic heterogeneity.
Chromosomes, Human, Pair 3↗
Autosomal dominant retinitis pigmentosa: absence of the rhodopsin proline----histidine substitution (codon 23) in pedigrees from Europe.
In exon 1 at codon 23 of the rhodopsin gene, a mutation resulting in a proline-to-histidine substitution has previously been observed in approximately 12% of American autosomal dominant retinitis pigmentosa (ADRP) patients. The region around the site of this mutation in the rhodopsin gene has been amplified and analyzed in affected individuals from 91 European ADRP pedigrees. The codon 23 mutation has been found to be absent in all cases, including a large Irish pedigree in which the disease gene has previously been shown to be closely linked to the rhodopsin locus. This indicates the presence of either allelic or nonallelic heterogeneity in ADRP.
Amino Acid Sequence↗
Linkage to D3S47 (C17) in one large autosomal dominant retinitis pigmentosa family and exclusion in another: confirmation of genetic heterogeneity.
Recently Dryja and his co-workers observed a mutation in the 23d codon of the rhodopsin gene in a proportion of autosomal dominant retinitis pigmentosa (ADRP) patients. Linkage analysis with a rhodopsin-linked probe C17 (D3S47) was carried out in two large British ADRP families, one with diffuse-type (D-type) RP and the other with regional-type (R-type) RP. Significantly positive lod scores (lod score maximum [Zmax] = +5.58 at recombination fraction [theta] = .0) were obtained between C17 and our D-type ADRP family showing complete penetrance. Sequence and oligonucleotide analysis has, however, shown that no point mutation at the 23d codon exists in affected individuals in our complete-penetrance pedigree, indicating that another rhodopsin mutation is probably responsible for ADRP in this family. Significantly negative lod scores (Z less than -2 at theta = .045) were, however, obtained between C17 and our R-type family which showed incomplete penetrance. Previous results presented by this laboratory also showed no linkage between C17 and another large British R-type ADRP family with incomplete penetrance. This confirms genetic heterogeneity. Some types of ADRP are being caused by different mutations in the rhodopsin locus (3q21-24) or another tightly linked gene in this region, while other types of ADRP are the result of mutations elsewhere in the genome.
Base Sequence↗
Fibrinolysis in pseudotumor cerebri.
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Blood Coagulation Disorders↗
Immunophenotypic profile of CNS lymphoma: a review of eighteen cases.
The cell surface antigenic phenotype of 18 cases of central nervous system (CNS) large-cell lymphoma (14 primary, four secondary) was examined by an immunoperoxidase technique using antibodies that identify B cell restricted and associated antigens. All cases were shown to be of B cell origin by virtue of the expression of monotypic immunoglobulin (Ig) (16 IgM, two IgG) and the pan B cell antigen B1 (CD20). A panel of monoclonal antibodies directed against B cell restricted and associated activation antigens including B5, Blast-1, Blast-2 (CD23), BB1, interleukin 2 receptor (IL2R, CD25), T9 (transferrin receptor) and TNK-TAR (4F2) was used on 12 of the cases. The majority expressed T9 and TNK-TAR. Blast-1 was expressed by less than half the cases and Blast-2 and B5 by one of 12 cases each. This is in contrast to 10 non-CNS diffuse large cell lymphomas where B5 and Blast-1 were present on all cases. This study confirms previous observations that primary CNS large cell lymphomas are of B cell derivation. Moreover, the differences in expression of B cell activation antigens on CNS large cell lymphomas as compared to non-CNS lymphomas raise the possibility that a subset of neoplastic B cells may have unique tropism for the CNS.
B-Lymphocytes↗
High-dose methotrexate for non-AIDS primary central nervous system lymphoma. Report of 13 cases.
Thirteen patients with primary lymphoma of the central nervous system (CNS) were treated with high-dose intravenous methotrexate (MTX), 3.5 gm/sq m, followed by calcium leucovorin rescue, at 3-week intervals, for three cycles. Eleven patients subsequently received radiation therapy to the whole brain, 30 to 44 Gy. Before radiation therapy, eight patients responded completely and four partially; there was one non-responder. The median Karnofsky score before high-dose MTX therapy was 60 and increased to 90 after treatment. Five of the eight complete responders reached a Karnofsky rating of 100. The three longest responders (one of whom received MTX only) were without recurrence of their disease at 29+, 32, and 32+ months posttherapy. The median response period is 9+ months. The median survival time from the date of the first MTX treatment is 9+ months, and the three longest survival times are 29+, 32+, and 54+ months. All patients received corticosteroids in either unchanging or diminishing dosages during therapy. It is concluded that primary CNS lymphoma is sensitive to high-dose MTX, which provides a safe and easily administered adjuvant to radiation therapy for this neoplasm.
Adult↗
Detection of Epstein-Barr virus by in situ hybridization. Progress toward development of a nonisotopic diagnostic test.
This work presents some initial quantitation of an in situ hybridization method for detection of Epstein-Barr (EB) virus nucleic acids. The purpose is to develop evaluative criteria for diagnosis of viral presence in clinical tissue specimens. In this work simultaneous denaturation of probe and target DNA and an alkaline phosphatase conjugate to detect biotinated probe were used as described by Unger et al. For evaluation of the hybridization, a variety of cell lines, both productively and latently infected, that were hybridized in situ using nick translated 32P-labeled viral probe sequences and counted by scintillation after the method of Lawrence and Singer were used. Producer cells (B95-8) showed intense foci of staining in approximately 5% of cells, with most of the other cells showing varying staining intensity. Raji cells showed varying amounts of signal from cell to cell. Namalwa cells exhibited one spot in most cells that was decreased after cells were treated with Actinomycin D (dactinomycin, Merck Sharp & Dohme, West Point, PA). Signal was identified in only a third of these same cells after sectioning. EB virus-negative Ramos cells showed no signal. The nuclear punctate nature of the signal generated is diagnostic of infected cells, and may be a useful test for cultured cells or pathologic specimens.
Autoradiography↗
How to organize a short-term course on neonatal nursing.
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Curriculum↗
Regrowth patterns of glioblastoma multiforme related to planning of interstitial brachytherapy radiation fields.
Recognition of the local nature of glioblastoma has generated an increasing interest in treatment using radioactive implants (interstitial brachytherapy). A key issue in such implantation is the configuration of the radiation field in relation to the resected tumor. In particular, should radiation be provided to the area from which the tumor has been resected? To clarify this issue, we evaluated patterns of tumor regrowth into this resected area in 62 patients. Three patterns of computed tomographic scan-documented tumor regrowth were recognized: preferential (regrowth to refill the resected area only), circumferential (regrowth into the resected area and previously uninvolved contiguous brain) and away (local regrowth into noncontiguous brain, sparing the surgical bed). Regrowth of the tumor 6.3 to 6.8 months after resection was seen in 59 of 62 patients (95.2%). Preferential regrowth was seen in 32 of 62 patients (51.6%), and circumferential regrowth was seen in 27 of 62 patients (43.5%). Regrowth away was seen in 3 of 62 patients (4.8%). Radiation fields planned for interstitial brachytherapy must adequately include the resected area because of the high incidence of tumor regrowth into that area.
Astrocytoma↗
Paraneoplastic neurological syndromes.
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Humans↗
Pre-irradiation internal carotid artery BCNU in treatment of glioblastoma multiforme.
High-dose 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) infusion into the internal carotid artery following cranial irradiation in the treatment of glioblastoma multiforme is accompanied by evidence of leukoencephalopathy in a significant number of patients. In an attempt to avoid this problem, a phase I trial was performed using intracarotid BCNU infusion before irradiation. Twenty-eight patients with grade III/III astrocytoma (World Health Organization Classification, equivalent to Kernohan grade IV) received a 400-mg infusion of BCNU into the infraophthalmic carotid artery. The treatment was repeated every 4 weeks for a total of four cycles prior to cranial irradiation (5500 to 6000 cGy). The major toxic sequelae included nausea and vomiting (24%), decreased visual acuity (14%), transient cerebral ischemia (3.5%), and thrombocytopenia (3.5%). Fatal leukoencephalopathy occurred in two patients. The median survival time was 37 weeks for all evaluable patients and 56+ weeks for those completing the protocol. The tumor response to drug infusion as judged by computerized tomography (CT) was complete in 22% of patients and partial in 22%; 56% showed no CT tumor response. Pre-irradiation intracarotid artery BCNU benefits a very small group of patients with grade III/III astrocytoma. The associated severe leukoencephalopathy makes this mode of therapy unacceptable for a phase III trial.
Adult↗