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K D Lanclos

Publications and source records attributed to K D Lanclos.

At least 37 records · Page 2Linked to original sources
PubMed1989

A C----T substitution at nt--101 in a conserved DNA sequence of the promotor region of the beta-globin gene is associated with "silent" beta-thalassemia.

Sequence analyses and dot-blot analyses with synthetic oligonucleotide probes have identified eight individuals in three Turkish families and one Bulgarian family with one chromosome having a C----T mutation at nucleotide position--101 relative to the Cap site of the beta-globin gene. This nucleotide is part of one of the conserved blocks of nucleotides within the promoter region; in vitro expression analyses with the chloramphenicol acetyltransferase system showed that this substitution will decrease the effectiveness of transcription. Five subjects had a thalassemia intermedia due to the additional presence of a known classical high hemoglobin (Hb) A2 beta-thalassemia mutation on the second chromosome; their hematologic condition was relatively mild. The three persons with a heterozygosity for the--101 C----T mutation had normal hematologic data without microcytosis but with high-normal levels of Hb A2 and a mild imbalance in chain synthesis. The newly discovered mutation is considered one of the silent types of beta-thalassemia. It is relatively rare because it was absent among several hundred normal and beta-thalassemia chromosomes.

Base Sequence↗
PubMed1989

Identical nucleotide sequences of the 3'A gamma globin gene enhancer elements from four different chromosomes.

We have determined the nucleotide sequence of the 2,360-bp long EcoRI fragment from four chromosomes; this fragment is located 3' to the A gamma globin gene and is considered to contain the enhancer element identified by Bodine and Ley. The chromosomes were from an Arabian sickle cell anemia patient with high Hb F and a homozygosity for haplotype No 31 and from a black sickle cell anemia patient with low Hb F and a homozygosity for haplotype No 19. A third chromosome carried the determinant for a nondeletional hereditary persistence of fetal hemoglobin seen in a Chinese subject, and the fourth was a normal chromosome from a Yugoslavian subject. Twenty-one differences were observed when a comparison was made with the published sequence; no differences were seen between the sequences of the four different samples except for an additional mutation in the Chinese. These data make it unlikely that specific mutations within this sequence are associated with increases in G gamma and A gamma production.

Base Sequence↗
PubMed1989

An A gamma type of nondeletional hereditary persistence of fetal hemoglobin with a T----C mutation at position -175 to the cap site of the A gamma globin gene.

The nondeletional types of hereditary persistence of fetal hemoglobin (ndHPFH) concern the continued synthesis of hemoglobin (Hb) F with either G gamma or A gamma chains in amounts varying from 5% to 30%. Several mutations have been identified in either the A gamma or G gamma promoter which are considered causative to the continued production of one of the two gamma chains because the substitutions occur in sequence motifs essential for the expression characteristics of the gamma-globin gene in the 3' position. We report the discovery of a T----C mutation at position -175 in the A gamma promoter which was associated with a greatly increased level of Hb F (with mainly A gamma) and a decreased level of Hb A in the one (Black) heterozygote who had a beta c gene in trans. The same mutation has been observed in the G gamma promoter of a Black heterozygote who had high levels of Hb F with G gamma chains only. A detailed comparison between these two individuals indicated significant differences in the levels of Hb F and Hb A which may result from an additional mutation at position -158 in the G gamma promoter.

Adult↗
PubMed1988

Biochemical and molecular aspects of beta-thalassemia types in northern Sardinia.

Forty-three patients with beta-thalassemia from Northern Sardinia (31 severe and polytransfused, six follow-up babies, five adults with mild thalassemia who were not transfusion dependent, and a young transfused patient was also affected by a disease of intermediate severity) were studied in order to establish the fetal hemoglobin composition, restriction fragment length polymorphism haplotypes at the beta-globin gene cluster, and the type(s) of mutation. Haplotype II was prevalent, [56/86 chromosomes (65%)], haplotype I was also fairly common, [22/86 chromosomes (25%)], while other types were relatively rare. The nonsense mutation at codon 39 was nearly exclusive, [76/80 chromosomes (95%)]. Other beta-thalassemia mutations occurred on chromosomes with haplotypes III, IX, X, and perhaps V, and a new type related to II. The mutated A gamma T gene was associated with type II, X, and the new type. Type IX was linked to a beta(0) gene and to an Xmn I site 5' to the G gamma gene, to a high G gamma globin level, and to a disease of mild severity. Type III was associated with a beta(+)-thalassemic gene. The (0)39 mutation linked to type II was associated with thalassemia intermedia in three patients.

Adolescent↗
PubMed1988

Clinical and genetic heterogeneity in black patients with homozygous beta-thalassemia from the southeastern United States.

The presence of various substitutions and deletions resulting in beta-thalassemia was studied in 19 black patients with homozygous beta-thalassemia and in numerous relatives; all patients were from Georgia, South Carolina, and Alabama. Methodology included gene mapping, amplification of genomic DNA with Taq polymerase, identification of known nucleotide substitutions or a single nucleotide deletion through hybridization with synthetic oligonucleotides, cloning and sequencing of a beta-globin gene, and sequencing of amplified genomic DNA. Of the 38 chromosomes tested, 21 (55%) had the A----G substitution at nt -29, eight (21%) had the C----T substitution at nt -88, three (8%) had the substitution at codon 24, while one each of the following abnormalities were also detected: frameshift at codon 6, a C----A mutation at nt 848 of the beta IVS-II (new), an A----T mutation at codon 61 (new), a deletion of 1.35 kilobases including the 5' end of beta, a Ggamma(Agamma delta beta)(0)-thalassemia, and one thalassemia determinant that remained unidentified. The C----A mutation at nt 848 of IVS-II occurred at a position 3 nucleotides 5' to the third exon, adjacent to the invariant AG dinucleotide of the acceptor sequence. The A----T mutation in codon 61 (AAG----TAG) resulted in the creation of a stop codon and thus in beta(0)-thalassemia. The various mutations occurred on chromosomes with different haplotypes; however, chromosomes with a specific mutation but with different haplotypes belonged to one specific framework, which suggested that crossovers were responsible for these different types. Hemoglobin (Hb) F levels were generally high (55% to 75% with 98.5% in one patient with beta(0)/beta(0)); a few patients with specific haplotypes and an alpha-thalassemia-2 heterozygosity had a lower Hb F level. The Ggamma in the Hb F was consistently high when the C----T mutation occurred at nt -158 to the Cap site of the Ggamma-globin gene; seven patients with +/+ at this site had an average Ggamma of 73.8%, eight patients with +/- had 64.8%, and one patient with -/- had 34.2%. Variations in hematologic values and in Hb F, Ggamma, and Hb A2 levels of relatives with a beta-thalassemia heterozygosity depended to some extent on the types of mutations or deletions and on the haplotypes of the chromosomes with the beta-thalassemia determinant.

Adolescent↗
PubMed1988

A chromosome with five gamma-globin genes.

Globin gene mapping of DNA from a Black newborn resulted in the detection of a chromosome with five gamma-globin genes. Based on results from digests with enzymes EcoRI and PstI, we concluded that the three genes between the 5'G gamma and 3'A gamma genes are G gamma genes with a possible 5' segment derived from A gamma. The high G gamma level in the fetal hemoglobin (Hb F) of the baby is consistent with this view. Family relationships were such that speculation as to the mechanism causing this quintuplication of the gamma-globin genes was not possible.

DNA↗
PubMed1987

The beta-delta crossover leading to the beta delta hybrid gene of hemoglobin P-Nilotic is located within 54 base-pairs of the 5' end of exon 2 or between codons 31 and 50.

The crossover region of the beta delta hybrid gene of the hemoglobin variant Hb P-Nilotic was defined in detail through cloning and sequencing of appropriate DNA segments. The crossover must have occurred without loss of bases within a 54 base-pair stretch of DNA between bases 275 and 330 (or between amino acid residues 31 and 50), indicating that the exon 1 and IVS-1 originate from beta, and exon 2, IVS-2 and exon 3 from delta. The data support the speculation that the IVS-1, in contrast to IVS-2, has no effect on the expression of this hybrid gene.

Adult↗
PubMed1987

Characterization of chromosomes with hybrid genes for Hb Lepore-Washington, Hb Lepore-Baltimore, Hb P-Nilotic, and Hb Kenya.

This study concerns the characterization of chromosomes with hybrid genes for Hb Lepore-Washington (44 chromosomes), for Hb Lepore-Baltimore (5 chromosomes), for Hb P-Nilotic (8 chromosomes), and for Hb Kenya (7 chromosomes) by determining a relatively large number of restriction enzyme polymorphism. Two, and possibly three, different Hb Lepore-Washington chromosomes were identified by specific haplotypes, while the haplotype of the Hb Lepore-Baltimore chromosome had its own characteristic pattern. A likely conclusion is that the crossovers leading to the formation of these chromosomes have occurred as independent events within the populations. Chromosomes with the delta beta-Lepore-Washington hybrid gene maintained specific characteristics (such as increased Hb F levels in heterozygotes, and high or low G gamma values in this Hb F) which have been observed in normal individuals with chromosomes having comparable haplotypes. Only one haplotype was observed for each of the chromosomes carrying either the beta delta-P-Nilotic hybrid gene or the A gamma beta hybrid gene of Hb Kenya.

Chromosome Mapping↗
PubMed1987

Haplotypes and alpha globin gene analyses in sickle cell anaemia patients from Kenya.

Over 60 patients from the Luo and Luhya tribes of Western Kenya, aged 1-23 years, with severe sickle cell anaemia were evaluated through haematological and gene mapping analyses. Nearly all (56 of 58 tested) were homozygous for haplotype 20 (Antonarakis et al, 1984) which is also frequently present in SS patients of the Central African Republic. All patients had a severe haemolytic anaemia with low Hb F levels and low levels of G gamma chains. An alpha-thalassaemia-2 heterozygosity (-alpha/alpha alpha; -3.7 kb deletion) was present in 26 of 53 patients tested; one patient was a homozygote [f(-alpha) = 0.255]. The alpha-thal-2 was type I in all but one subject with this deficiency; the one exception had an alpha-thal-2 heterozygosity, type II. Heterozygosity for the alpha-thal-2 did not affect the clinical condition nor the haematology; Hb F levels were somewhat lower in SS patients with -alpha/alpha alpha than in those with alpha alpha/alpha alpha. A high frequency was observed for the absence of an Xba I restriction site 5' to the zeta globin gene; the frequency of this anomaly [f(Xba I-)] was estimated at 0.39 for the chromosome with two alpha globin genes and at 0.74 for that with the alpha-thal-2 deletion. An Apa I restriction site polymorphism was observed in the IVS-II of the alpha 2 globin gene; 13 alpha 2 genes of 53 normal (alpha alpha/) chromosomes had this restriction site which was absent in the hybrid alpha globin gene of the -alpha/chromosome.

Adolescent↗
PubMed1986

Synthesis of a fixed-length single-stranded DNA probe by blocking primer extension in bacteriophage M13.

A simple and efficient technique has been developed for preparing radiolabeled single-stranded (ss) probes of determined length and high specific radioactivity. The human beta-globin gene intervening segment II (IVSII) fragment (0.9-kb) was inserted between the EcoRI and BamHI sites of M13mp11 and used as a template for ss probe synthesis. The M13 hybridization probe primer (M13 Hpp) was annealed to the recombinant M13mp11-beta IVSII template DNA. This M13 Hpp was next blocked by the enzymatic addition of a dideoxy adenosine monophosphate (ddAMP) residue to the 3' OH group of the primer. The M13 universal sequencing primer was then annealed and used to prepare an ss copy of the beta-IVSII fragment. Synthesis of the ss fragment was terminated by the presence of the dd-blocked M13 Hpp yielding a specific 0.9-kb ss beta-IVSII probe.

Cloning, Molecular↗
PubMed1986

The effect of alpha-thalassemia on the level of hybrid hemoglobin variants in heterozygotes.

The influence of a relative deficiency in alpha chain production on the amount of Hemoglobins Kenya, P-Nilotic, and Lepore was determined. The level of these hybrid hemoglobins in heterozygotes was correlated to various states of alpha chain deficiency by: 1) quantitation of the variants in blood samples and comparing these data with the number of alpha globin genes determined by gene mapping, 2) in vitro recombination experiments involving isolated non-alpha chains and normal alpha chains, and 3) in vitro heat stability analyses of the isolated hemoglobins. Hb Kenya, composed of normal alpha and gamma-beta hybrid chains, is heat labile, has a decreased ability to combine with alpha chains, and its level in heterozygotes is greatly decreased when a concomitant alpha-chain deficiency (alpha-thalassemia) is present. Such a posttranslational control mechanism was not observed for Hb Lepore, with normal alpha chains and delta-beta hybrid chains, and Hb P-Nilotic, with normal alpha chains and beta-delta hybrid chains. The latter two variants are heat stable, and their hybrid chains combine equally well as normal beta chains with normal alpha chains. Hb P-Nilotic is more heat stable than Hb A and its in vitro formation is increased over that of Hb S, and perhaps even Hb A, in conditions of severe alpha chain deficiency.

Fetal Hemoglobin↗
PubMed1982

Effect of calmodulin inhibitor, Stelazine, on the endocytosis of vitellogenin and transglutaminase activity in Xenopus laevis oöcytes.

The specific endocytosis of vitellogenin was measured in the presence of various concentrations of Stelazine, a specific inhibitor of the calcium regulating protein, calmodulin. Stelazine (200 microM) was found to inhibit the endocytosis of vitellogenin by 63% as determined by decreased uptake of vitellogenin into transitional yolk bodies and yolk platelets. The enzymatic activity of transglutaminase, a calcium-requiring enzyme implicated in receptor-mediated endocytosis, was not affected by these concentrations of Stelazine.

Acyltransferases↗
PubMed1979

Isolation and characterization of the nuclear matrix from the male Xenopus laevis following estrogen administration: kinetics of [3H] uridine incorporation.

At various times following estrogen administration, the nuclear matrix was isolated from the liver of male Xenopus laevis by sucrose gradient centrifugation of nuclei treated with a high-salt buffer and DNase I in the presence of a proteolytic inhibitor (PMSC--phenylmethyl sulfonyl chloride). Electron micrographs of the nuclear matrix demonstrate a sponge-like network attached to a well-defined inner envelope with a ribosome-free outer envelope. Chemical analyses show that the HSB-DNase-treated nuclei consist of 16% DNA, 2% RNA, and 82% protein, a composition that is consistent with that of nuclear matrices isolated from other species. The specific activity of the matrix-associated RNA following estrogen treatment appears to be maximally enhanced after 5 h and decreases until approximately 12 h, when the activity begins to increase again.

Animals↗