Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Stop codon”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,315 records · Page 73Linked to original sources
PubMed1990

Primary structure of the oligo-1,6-glucosidase of Bacillus cereus ATCC7064 deduced from the nucleotide sequence of the cloned gene.

The gene coding for Bacillus cereus ATCC7064 (mesophile) oligo-1,6-glucosidase was cloned within a 2.8-kb SalI-EcoRI fragment of DNA, using the plasmid pUC19 as a vector and Escherichia coli C600 as a host. E. coli C600 bearing the hybrid plasmid pBCE4 accumulated oligo-1,6-glucosidase in the cytoplasm. The cloned enzyme coincided absolutely with B. cereus oligo-1,6-glucosidase in its Mr (65,000), in its electrophoretic behavior on a polyacrylamide gel with or without sodium dodecyl sulfate, in its isoelectric point (4.5), in the temperature dependence of its stability and activity, and in its antigenic determinants. The nucleotide sequence of B. cereus oligo-1,6-glucosidase gene and its flanking regions was determined with both complementary strands of DNA (each 2838 nucleotides). The gene consisted of an open reading frame of 1674 bp commencing with a ATG start codon and followed by a TAA stop codon. The amino acid sequence deduced from the nucleotide sequence predicted a protein of 558 amino acid residues with a Mr of 66,010. The amino acid composition and Mr were comparable with those of B. cereus oligo-1,6-glucosidase. The predicted N-terminal sequence of 10 amino acid residues agreed completely with that of the cloned ligo-1,6-glucosidase. The deduced amino acid sequence of B. cereus oligo-1,6-glucosidase was 72% and 42% similar to those from Bacillus thermoglucosidasius KP1006 (DSM2542, obligate thermophile) oligo-1,6-glucosidase and from Saccharomyces carlsbergensis CB11 alpha-glucosidase, respectively. Predictions of protein secondary structures along with amino acid sequence alignments demonstrated that B. cereus oligo-1,6-glucosidase may take the similar (alpha/beta)8-barrel super-secondary structure, a barrel of eight parallel beta-strands surrounded by eight alpha-helices, in its N-terminal active site domain as S. carlsbergensis alpha-glucosidase and Aspergillus oryzae alpha-amylase.

Amino Acid Sequence↗
PubMed2005

A vancomycin-dependent VanA-type Enterococcus faecalis strain isolated in Japan from chicken imported from China.

AIMS: The characterization of KC122.1, which is a vancomycin-dependent VRE (Vancomycin-resistant enterococci) (Enterococcus faecalis) and the first case in Japan of a VRE isolate obtained from chicken meat imported from China. METHODS AND RESULTS: PCR amplification of vanA, vanS and ddl gene and direct sequencing of the PCR products were performed. KC122.1 was a VanA-type VRE showing high-level vancomycin resistance and low-level teicoplanin resistance, and its vanS gene had three point mutations. The ddl gene of KC122.1 was sequenced and two changes were found at the ninth codon (GCC-GAC) and the stop codon (TAA-CAA). The latter change was also found in the laboratory strain E. faecalis FA2-2. CONCLUSIONS: Three point mutations in vanS resulted in high-level vancomycin resistance and low-level teicoplanin resistance. The change at the ninth codon resulted in the inactivation of the ddl gene and vancomycin-dependent growth. An eight amino acid extension at the C-terminal did not impair the function of the D-Ala : D-Ala ligase. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first example of the isolation of VRE from chicken meat imported from China and the first vancomycin-dependent VRE from a nonhuman source.

Animals↗
PubMed2000

The bulged nucleotide in the Escherichia coli minimal selenocysteine insertion sequence participates in interaction with SelB: a genetic approach.

The UGA codon, which usually acts as a stop codon, can also direct the incorporation into a protein of the amino acid selenocysteine. This UGA decoding process requires a cis-acting mRNA element called the selenocysteine insertion sequence (SECIS), which can form a stem-loop structure. In Escherichia coli, selenocysteine incorporation requires only the 17-nucleotide-long upper stem-loop structure of the fdhF SECIS. This structure carries a bulged nucleotide U at position 17. Here we asked whether the single bulged nucleotide located in the upper stem-loop structure of the E. coli fdhF SECIS is involved in the in vivo interaction with SelB. We used a genetic approach, generating and characterizing selB mutations that suppress mutations of the bulged nucleotide in the SECIS. All the selB suppressor mutations isolated were clustered in a region corresponding to 28 amino acids in the SelB C-terminal subdomain 4b. These selB suppressor mutations were also found to suppress mutations in either the loop or the upper stem of the E. coli SECIS. Thus, the E. coli SECIS upper stem-loop structure can be considered a "single suppressible unit," suggesting that there is some flexibility to the nature of the interaction between this element and SelB.

Bacterial Proteins↗
PubMed1985

Genetic and biochemical analysis of transformation-competent, replication-defective simian virus 40 large T antigen mutants.

To study the role of the biochemical and physiological activities of simian virus 40 (SV40) large T antigen in the lytic and transformation processes, we have analyzed DNA replication-defective, transformation-competent T-antigen mutants. Here we describe two such mutants, C8/SV40 and T22/SV40, and also summarize the properties of all of the mutants in this collection. C8/SV40 and T22/SV40 were isolated from C8 and T22 cells (simian cell lines transformed with UV-irradiated SV40). Early regions encoding the defective T antigens were cloned into a plasmid vector to generate pC8 and pT22. The mutations responsible for the defects in viral DNA replication were localized by marker rescue, and subsequent DNA sequencing revealed missense and one nonsense mutation. The T22 mutation predicts a change of histidine to glutamine at residue 203. C8 has two mutations, one predicts lysine224 to glutamamic acid and the other changes the codon for glutamic acid660 to a stop codon; therefore, C8 T antigen lacks the 49 carboxy-terminal amino acids. pC8A and pC8B were constructed to contain the C8 mutations separately. Plasmids pT22, pC8, pC8A, and pC8B were able to transform primary rodent cell cultures. T22 T antigen is defective in binding to the SV40 origin. C8B (49-amino-acid truncation) is a host-range mutant defective in a late function in CV-1 but not BSC cells. Analysis of T antigens in mutant SV40-transformed mouse cells suggests that the replicative function of T antigen is important in generating SV40 DNA rearrangements that allow the expression of "100K" variant T antigens in the transformants.

Animals↗
PubMed2006

A novel fibrinogen Bbeta chain frameshift mutation in a patient with severe congenital hypofibrinogenaemia.

Congenital afibrinogenemia and severe hypofibrinogenemia are severe bleeding disorders characterized by either undetectable or very low levels of fibrinogen in patients' plasma and platelets. A majority of the reported cases are caused by mutations in the fibrinogen Aalpha chain. In this study, we identified a genetic defect in the fibrinogen Bbeta-chain (FGB) underlying severe hypofibrinogenemia. The propositus frequently displayed bleeding episodes with a prolonged blood-clotting time (thrombin time > 180 s, activated partial thromboplastin time > 300 s, prothrombin time > 120 s) and had a very low level of plasma fibrinogen (1.7-1.8 mg/dl). His parents had a consanguineous marriage, and their functional and immunological fibrinogen was approximately half of the normal level. The platelet fibrinogen level of the propositus could not be detected by western blotting, and his platelet aggregation was severely impaired. DNA screening of the whole fibrinogen gene revealed a homozygous GGGG-->GGG mutation at nucleotide 7,969-7,972 in his FGB gene. The propositus' parents are both heterozygous for this mutation. This mutation contributes to Gly419-->Val, and the 419-434 codons are frame shifted, and a stop codon is formed at codon 435. The predicted truncated Bbeta-chain is 27 amino acids shorter than the normal Bbeta-chain and a central beta-strand in the globular betaC domain is absent, which may lead to destabilization of the entire beta-domain. To the best of our knowledge, this is the first report of such a mutation which is associated with severe hypofibrinogenemia.

Adult↗
PubMed1998

Identification of a new inborn error in bile acid synthesis: mutation of the oxysterol 7alpha-hydroxylase gene causes severe neonatal liver disease.

We describe a metabolic defect in bile acid synthesis involving a deficiency in 7alpha-hydroxylation due to a mutation in the gene for the microsomal oxysterol 7alpha-hydroxylase enzyme, active in the acidic pathway for bile acid synthesis. The defect, identified in a 10-wk-old boy presenting with severe cholestasis, cirrhosis, and liver synthetic failure, was established by fast atom bombardment ionization-mass spectrometry, which revealed elevated urinary bile acid excretion, a mass spectrum with intense ions at m/z 453 and m/z 510 corresponding to sulfate and glycosulfate conjugates of unsaturated monohydroxy-cholenoic acids, and an absence of primary bile acids. Gas chromatography-mass spectrometric analysis confirmed the major products of hepatic synthesis to be 3beta-hydroxy-5-cholenoic and 3beta-hydroxy-5-cholestenoic acids, which accounted for 96% of the total serum bile acids. Levels of 27-hydroxycholesterol were > 4,500 times normal. The biochemical findings were consistent with a deficiency in 7alpha-hydroxylation, leading to the accumulation of hepatotoxic unsaturated monohydroxy bile acids. Hepatic microsomal oxysterol 7alpha-hydroxylase activity was undetectable in the patient. Gene analysis revealed a cytosine to thymidine transition mutation in exon 5 that converts an arginine codon at position 388 to a stop codon. The truncated protein was inactive when expressed in 293 cells. These findings indicate the quantitative importance of the acidic pathway in early life in humans and define a further inborn error in bile acid synthesis as a metabolic cause of severe cholestatic liver disease.

Amino Acid Sequence↗
PubMed2001

Aberrant fibrin formation and cross-linking of fibrinogen Nieuwegein, a variant with a shortened Aalpha-chain, alters endothelial capillary tube formation.

A congenital dysfibrinogenemia, fibrinogen(Nieuwegein), was discovered in a young man without any thromboembolic complications or bleeding. A homozygous insertion of a single nucleotide (C) in codon Aalpha 453 (Pro) introduced a stop codon at position 454, which resulted in the deletion of the carboxyl-terminal segment Aalpha 454-610. The ensuing unpaired cysteine at Aalpha 442 generated fibrinogen-albumin complexes of different molecular weights. The molecular abnormalities of fibrinogen(Nieuwegein) led to a delayed clotting and a fibrin network with a low turbidity. Electron microscopy confirmed that thin fibrin bundles were organized in a fine network. The use of fibrinogen(Nieuwegein)-derived fibrin (fibrin(Nieuwegein)) in an in vitro angiogenesis model resulted in a strong reduction of tube formation. The ingrowth of human microvascular endothelial cells (hMVEC) was independent of alpha(v)beta(3), indicating that the reduced ingrowth is not due to the absence of the RGD-adhesion site at position Aalpha 572-574. Rather, the altered structure of fibrin(Nieuwegein) is the cause, since partial normalization of the fibrin network by lowering the pH during polymerization resulted in an increased tube formation. Whereas factor XIIIa further decreased the ingrowth of hMVEC in fibrin(Nieuwegein), tissue transglutaminase (TG), which is released in areas of vessel injury, did not. This is in line with the absence of the cross-linking site for TG in the alpha-chains of fibrinogen(Nieuwegein). In conclusion, this newly discovered congenital dysfibrinogenemia has a delayed clotting time and leads to the formation of an altered fibrin structure, which could not be cross-linked by TG and which is less supportive for ingrowth of endothelial cells.

Adult↗
PubMed2006

Clinical case seminar: metastatic follicular thyroid carcinoma arising from congenital goiter as a result of a novel splice donor site mutation in the thyroglobulin gene.

CONTEXT: Defects in thyroglobulin (Tg) synthesis are one of the causes of thyroid dyshormonogenesis. Only a few mutations in the Tg gene have been described. OBJECTIVES: We describe a novel Tg gene mutation and discuss the mechanisms by which it causes dyshormonogenesis with subsequent malignant transformation. CASES: Two siblings aged 21 and 19 yr presented with recurrent goiters for which they had undergone multiple thyroid surgeries since early childhood. The older sibling was diagnosed with metastatic follicular thyroid carcinoma at age 15 yr. METHODS: The entire coding region and intron-exon boundaries of the Tg gene were amplified and sequenced from the patients. We also sequenced the boundaries of exon 5 and intron 5 from both parents. RT-PCR amplification of a cDNA fragment encompassing exons 4-6 was also performed. RESULTS: A homozygous G to A point mutation at position +1 of the splice donor site of intron 5 (g.IVS5+1G-->A) was detected in both patients, whereas a monoallelic mutation was found in their parents. RT-PCR amplification of a cDNA fragment covering exons 4-6 revealed a 191-bp fragment in the patients and 351- and 191-bp fragments in the parents. Sequence analysis of these two fragments confirmed deletion of exon 5 in the 191-bp fragment. CONCLUSIONS: Aberrant splicing occurred as a result of the g.IVS5+1G-->A mutation, which caused fusion of exons 4 and 6, resulting in the frame shift at codon position 141 and a premature stop codon at position 147 (FS141-->147X). The malignant transformation is likely a result of prolonged TSH stimulation.

Adenocarcinoma, Follicular↗
PubMed1997

Hereditary defect in biosynthesis of aldosterone: aldosterone synthase deficiency 1964-1997.

We studied two of the three patients with a hereditary defect in the biosynthesis of aldosterone originally described by Visser and Cost in 1964. All three presented as newborns with salt-losing syndrome and failure to thrive. The original biochemical studies showed a defect in the 18-hydroxylation of corticosterone. According to the nomenclature proposed by Ulick, this defect would be termed corticosterone methyl oxidase deficiency type I. We measured plasma steroids in the untreated adult patients and performed molecular genetic studies. Aldosterone and 18-OH-corticosterone were decreased, whereas corticosterone and 11-deoxycorticosterone were elevated, thus confirming the diagnosis of corticosterone methyl oxidase deficiency type I. Cortisol and its precursors were in the normal range. Genetic defects in the gene CYP11B2 encoding aldosterone synthase (P450c11Aldo) have been described in a few cases. We identified a homozygous single base exchange (G to T) in codon 255 (GAG) causing a premature stop codon E255X (TAG). This mutation destroys a Aoc II restriction site. Digestion of a PCR fragment containing exon 4 of CYP11B2 (261 bp) with this restriction enzyme revealed in the two patients homozygous for the E255X mutation only a 261-bp fragment, whereas the heterozygous parents had three fragments (261 bp from the mutant allele and 194 and 67 bp from the wild-type allele). The mutant enzyme had lost the five terminal exons containing the heme binding site, and thus there was a loss of function enzyme. We conclude that the biochemical phenotype of these prismatic cases of congenital hypoaldosteronism can be explained by the patients genotype.

18-Hydroxycorticosterone↗
PubMed2004

Detection and evaluation of intron retention events in the human transcriptome.

Alternative splicing is a very frequent phenomenon in the human transcriptome. There are four major types of alternative splicing: exon skipping, alternative 3' splice site, alternative 5' splice site, and intron retention. Here we present a large-scale analysis of intron retention in a set of 21,106 known human genes. We observed that 14.8% of these genes showed evidence of at least one intron retention event. Most of the events are located within the untranslated regions (UTRs) of human transcripts. For those retained introns interrupting the coding region, the GC content, codon usage, and the frequency of stop codons suggest that these sequences are under selection for coding potential. Furthermore, 26% of the introns within the coding region participate in the coding of a protein domain. A comparison with mouse shows that at least 22% of all informative examples of retained introns in human are also present in the mouse transcriptome. We discuss that the data we present suggest that a significant fraction of the observed events is not spurious and might reflect biological significance. The analyses also allowed us to generate a reliable set of intron retention events that can be used for the identification of splicing regulatory elements.

Animals↗
PubMed2000

Lysyl-tRNA synthetase of Bacillus stearothermophilus molecular cloning and expression of the gene.

The gene of the lysyl-tRNA synthetase of Bacillus stearothermophilus NCA1503 was cloned and sequenced. The gene consists of 1485 bp nucleotides commencing with an ATG start codon and ending with a TAA stop codon, and encodes a polypeptide of 493 amino acids. The recombinant enzymes were expressed in E. coli using an expression plasmid containing the T7 RNA polymerase/promoter.

Amino Acid Sequence↗
PubMed1998

Molecular genetic study in two patients with congenital hypoaldosteronism (types I and II) in relation to previously published hormonal studies.

We performed a molecular genetic study in two patients with congenital hypoaldosteronism. An original study of these patients was published in this Journal in 1982. Both index cases, a girl (patient 1) and a boy (patient 2). presented with salt-wasting and failure to thrive in the neonatal period. Parents of patient 1 were not related, whereas the parents of patient 2 were cousins. Endocrine studies had shown a defect in 18-oxidation of 18-OH-corticosterone in patient 1 and a defect in the 18-hydroxylation of corticosterone in patient 2. Plasma aldosterone was decreased in both patients, whereas 18-OH-corticosterone was elevated in patient 1 and decreased in patient 2. Plasma corticosterone and 11-deoxycorticosterone were elevated in both patients, whereas cortisol and its precursors were in the normal range. According to the nomenclature proposed by Ulick, the defects are termed corticosterone methyl oxidase (CMO) deficiency type II in patient 1, and type I in patient 2 respectively. Genetic defects in the gene CYP11B2 encoding aldosterone synthase have been described in a few cases. In patient 1, we identified only one heterozygous amino acid substitution (V386A) in exon 7, which has no deleterious effect on the enzyme activity. In patient 2 and his older brother, we identified a homozygous single base exchange (G to T) in codon 255 (GAG), causing a premature stop codon E255X (TAG). The mutant enzyme has lost the five terminal exons containing the haem binding site, and is thus a loss of function enzyme. This is only the second report of a patient with CMO deficiency type II without a mutation in the exons and exon-intron boundaries, whereas the biochemical phenotype of the two brothers with CMO deficiency type I can be explained by the patient's genotype.

Base Sequence↗
PubMed2001

Messenger RNAs encoding the beta subunits of guinea pig (Cavia porcellus) luteinizing hormone (gpLH) and putative chorionic gonadotropin (gpCG) are transcribed from a single-copy gpLH/CGbeta gene.

Neither gene locus nor gene sequence characterizations have been reported for the beta subunits of guinea pig (gp) LH and putative gp chorionic gonadotropin (CG). Descriptions of this locus would allow comparison with functionally relevant molecular genetic features of other species' homologous loci including the single-copy equid LH/CGbeta gene and the primate LHbeta-CGbeta gene cluster locus. Contiguous cDNA and genomic DNA fragments spanning the entire mature coding sequence of gpLHbeta mRNA, gpCGbeta mRNA and a homologous gpLH/CGbeta gene were amplified using PCR methodologies. With the exception of one silent mutation, the two cDNA and the genomic sequences were identical where they overlapped. Comparison of guinea pig coding sequence with LHbeta, CGbeta and LH/CGbeta sequences of other vertebrate species revealed the following order of similarity expressed as per cent coding sequence identity: rhinoceros LHbeta (83.6%)>pig LHbeta (81.8%)>donkey LH/CGbeta=bovine LHbeta (81.5%)> horse LH/CGbeta (80.6%)>dog LHbeta (79.7%)>human LHbeta (78.2%)>rat LHbeta (77.9%)>human CGbeta (75.8%)>turkey LHbeta (52.7%); values that are generally consistent with recently postulated phylogenetic relationships. Like the consensus mammalian LHbeta gene, the 5'-flanking region of the gpLH/CGbeta gene contains a single TATA sequence 37 bp upstream of the translation start codon. The first in-frame stop codon occurred at codon position +122 which is consistent with the 121 amino acid residue length of the consensus mammalian mature LHbeta peptide. To estimate gene copy number, full-length gpLHbeta cDNA was radiolabeled and hybridized to Southern blots of guinea pig genomic DNA digested with a panel of six restriction endonucleases. The resulting simple hybridization pattern strongly suggested that there is a single-copy gpLH/CGbeta gene. Northern analysis of total pituitary RNA using the same probe indicated that gpLHbeta transcript size is indistinguishable from that of consensus mammalian pituitary LHbeta mRNAs ( approximately 750 nucleotides). Despite amplifying gpCGbeta from placental RNA, positive signal was not detected in Northern blot lanes containing guinea pig total RNA prepared from placentae collected at three gestational ages (17.3 days, 24.3 days and 68 days (term)). Other data suggest that inability to detect Northern blot signal could have been due to low relative tissue concentrations of gpCGbeta transcript and/or sampling at gestational time-points that missed peak periods of mRNA expression. We conclude that, with respect to gene copy number, coding sequence and pituitary mRNA size, the gpLH/CGbeta gene locus reflects the CTP-less consensus mammalian LHbeta condition. However, based on the capacity of this single-copy gene to express in both pituitary and placental tissues, gpLH/CGbeta also exhibits functional similarities with the single-copy equine LH/CGbeta locus.

Amino Acid Sequence↗
PubMed1999

[Hemoglobinopathy in Japan: detection and analysis].

By means of systematic abnormal Hb surveys of people living in eight districts (Okayama, Shimane, Kagawa, Hyogo, Osaka, Nara, Aichi, and Yamanashi Prefectures) using isoelectric focusing, the number of abnormal Hbs discovered and identified among 301,190 subjects was 128. The frequency was estimated to be about one per 2,350. Recently, however, abnormal Hb carriers have been found among individuals with high or low levels of Hb A1c or with an abnormal HPLC pattern. These carriers were found when glyco-HPLC was used to determine the HbA1c level for detection and diagnosis of diabetes mellitus in physical check-ups of inhabitants in each prefecture. To date, 1,227 cases of abnormal Hbs have been detected by isoelectric focusing and glyco-HPLC. These Hbs were analyzed by protein chemistry and DNA analytical methods. The most typical Hbs found in Japan have been Hb J-Cape Town (an alpha-chain variant) and Hb Riyadh (a beta-chain variant). Homozygotes for Hb J-Cape Town, Hb Ube-2, Hb Hamadan, Hb G-Szuhu and Hb Takamatsu have been discovered among abnormal Hb carriers. The carriers of Hb M-Hyde Park and Hb Koln, which cause hemolytic anemia due to their molecular instability, have been found in some parts of Japan, but by clinical examination rather than by Hb survey. On the other hand, alpha- and beta-thals have often been detected in blood samples with a high or low HbA2 level or in abnormal Hb such as Hb H, during systematic surveys for abnormal Hb. Peripheral blood examinations of these patients revealed typical data, a low MCV, MCH, and sometimes low Hb levels. The diagnosis was made by DNA analyses of the nucleotide sequencing of the beta-globin gene for beta-thals and of the alpha-globin gene arrangement for alpha-thals. beta-Thals found in Japanese mainly involve a point mutation, such as-31CapA-->G(in ATA box) and beta 90 codon GAG-->TAG(creation of a stop codon). The alpha-thals had genotypes of -alpha 3.7/alpha alpha for alpha-thal-2, -SEA/alpha alpha for alpha-thal-1 and -SEA/-alpha 3.7 for Hb H disease.

Asian People↗
PubMed2000

Cloning and sequencing of cel5Z gene from Erwinia chrysanthemi PY35.

The phytopathogenic bacterium Erwinia chrysanthemi (Ech) secretes multiple isozymes of plant cell wall disrupting enzymes such as pectate lyase and endoglucanases. We cloned genomic DNA from Ech PY35 digested with Sau3AI and ligated into pBluescript II SK+. One of the E. coli XL1-blue clones had the ability to hydrolyze carboxymethyl cellulose and polygalacturonic acid. By subsequent subcloning from this 2.9 kb fragment, we obtained a 2.0 kb (pPY401), designated cel5Z, which had the activity of hydrolyzation of carboxymethyl cellulose. The cel5Z gene had an open reading frame (ORF) of 1,281 bp starting with an ATG start codon and followed by a TAA stop codon, encoding 426 amino acids with a signal peptide of 41 amino acids. Since the deduced amino acid sequence of this protein was very similar to that of CelE of Pseudomonas fluorescens, and had the conserved region, VIYEIYNEPL, it belonged to the glycoside hydrolase family 5 of EC 3.2.1.4. The molecular mass of Cel5Z protein from E. coli XL1-blue, as analyzed by CMC-SDS-PAGE, appeared to be 42 kDa. The optimum pH was 6, and the optimum temperature was about 40 degrees C for its enzymatic activity.

Amino Acid Sequence↗
PubMedDate not supplied

Phenotypic and genotypic characterization of glioblastoma multiforme with epithelial differentiation and adenoid formations.

Rare examples of high-grade gliomas show focal epithelial differentiation, which may require distinction from colliision tumors. These epithelial constituents are not well-characterized immunophenotypically and have rarely been subjected to genotyping. We describe a case of a 54-year-old female with a short history of hemiparesis who was found to have an absolute lymphocytosis and a heterogeneously enhancing frontotemporal tumor. Cytological and histological examination of brain biopsies confirmed the presence of a glioblastoma multiforme also containing CAM5.2/CK7/BerEP4/CEA/EMA-immunopositive and GFAP-immunonegative nests of epithelial cells with a high proliferative index and focal glandular differentiation. Hematological investigations confirmed a diagn of chronic lymphocytic leukemia (CLL) with no demonstrable CNS involvement. Genetic analysis using microsatellite markers and specimens obtained by laser capture microdissection of the CNS tumor and normal brain tissue, showed that both the glial and epithelial components of the brain tumor had identical losses of 2/2 informative markers on chromosome 17p13 and 5/5 informative markers on chromosome 10q22-26. The glial and epithelial components also shared an identical 2 base pair deletion in the TP53 gene at codon 209, exon 6, introducing a stop codon at codon 214. No losses at any of the above loci and no TP53 mutation were detected in the leukemic cells. These results suggest both components of the brain tumor, although differing in phenotype, share the same genetic lineage.

Brain Neoplasms↗
PubMed2005

Hb Tak: a beta chain elongation at the end of the beta chain, in a Taiwanese.

Hemoglobin (Hb) variants caused by an elongation of the beta-globin chain are rare. In this study, we present the first case of Hb Tak in a Taiwanese. Hb Tak is caused by an insertion of the dinucleotides AC into codon 146 that abolishes the normal stop codon at position 147. This insertion results in a frameshift causing elongation of the beta chain by 11 amino acids.

Female↗
PubMed1995

Predictive value of precore hepatitis B virus mutations in spontaneous and interferon-induced hepatitis B e antigen clearance.

We previously reported two mutually exclusive mutations in the precore region of hepatitis B virus: M1 (T-1856, proline-serine substitution at codon 15) and M2 (A-1896, stop codon at codon 28). This study was conducted to determine if the presence of precore mutants affect spontaneous or interferon (IFN)-induced hepatitis B e antigen (HBeAg) clearance. Sera from 201 hepatitis B e antigen positive Chinese patients (including 106 who participated in a controlled trial of IFN therapy) with chronic hepatitis B virus (HBV) infection were analyzed by direct sequencing of HBV DNA after amplification by polymerase chain reaction (PCR) assay. Forty-three (21%) patients had M1 (T-1856), and 20 patients (10%) had M2 (A-1896). During a follow-up period of 1 to 7 years, 75%, 28%, and 26% of those with M2 (A-1896), M1 (T-1856), and wild type sequence respectively, cleared HBeAg (P < .0001). Eighteen (67%) of 27 patients with wild-type sequence but none of 10 patients who had M1 (T-1856) in their initial samples developed M2 (A-1896) after loss of HBeAg (P < .0001). Sustained antiviral response was achieved in 55%, 0%, and 17% of interferon-treated patients who had M2 (A-1896), M1 (T-1856), and wild-type sequence, respectively, initially (P = .04). However, patients with M2 (A-1896) were also more likely to have elevated pretreatment aminotransferase levels (P = .02). In summary, HBeAg-positive Chinese patients with M2 (A-1896) were mor likely to clear HBeAg, and to do so earlier.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗