Biomedical subjects
B Eng
Publications and source records attributed to B Eng.
De novo mutation of the beta-globin gene initiation codon (ATG-->AAG) in a Northern European boy.
We present a case of beta-thalassemia intermedia involving a 13-year-old boy of Northern European descent. His mother, father and older sister have normal hematologic indices. Molecular studies demonstrate that the proband carries a novel mutation of the beta-globin gene initiation codon (ATG-->AAG) which should give rise to beta(0)-thalassemia trait. The possibility of non-paternity was excluded, indicating that the novel mutation was the result of a de novo event. A review of the literature indicates that mutations involving the beta-globin gene initiation codon can give rise to a more severe phenotype than is generally associated with most other beta(+) or beta(0) mutations.
Novel mutation of the alpha 2-globin gene initiation codon (ATG-->A-G) in a Vietnamese girl with Hb H disease.
Explore the source record for details and available documents.
Novel beta 0-thalassemia mutation in a Canadian woman of British descent (codons 72/73, -AGTGA, +T).
Explore the source record for details and available documents.
Canuck place: a hospice for dying children.
Parents will never face a more stressful event than the news that their child will die. A child's terminal illness challenges every belief, emotion and dream that a parent has. In addition to the emotional drain, caring for a dying child is physically exhausting. Moreover, the child's illness affects the lives of all brothers, sisters, aunts, uncles and grandparents. The care of these children and their families demands a holistic program of services, including physical and emotional support, as well as tangible ways to relieve parents from the continuous 24-hour care of their child. And after the child has died, the emotional support must continue as families learn to face life without their child.
Alteration of glomerular permeability to macromolecules induced by cross-linking of beta 1 integrin receptors.
Altered glomerular epithelial cell attachment to the glomerular basement membrane is an important pathogenetic factor in increased glomerular permeability to proteins. We have previously presented evidence that antibodies reactive with integrin matrix receptors on glomerular epithelial cells inhibit adhesion of these cells and may be involved in the production of proteinuria in vivo. Therefore, we utilized intact glomeruli in an in vitro system to directly assess the effect of anti-beta 1-integrin antibody on glomerular permeability. Permeability to albumin (Palb) was calculated from the volume response of glomeruli to a transcapillary oncotic gradient. Anti-beta 1-integrin increased Palb in a dose- and time-dependent manner. Palb was increased to 0.70 +/- 0.05 whereas normal rabbit IgG had no effect (0.10 +/- 0.04). F(ab')2 fragments of antibody increased Palb to a similar degree whereas Fab fragments had no effect (0.10 +/- 0.06). Cross-linking of Fab fragments, however, with a second antibody restored their ability to increase Palb (0.60 +/- 0.09), demonstrating the importance of integrin cross-linking in producing the observed effect. Intact, F(ab')2 and Fab fragments of anti-beta 1 antibody all inhibited adhesion of glomerular epithelial cells to fibronectin, laminin, and types I and IV collagen, although the degree of inhibition by Fab fragments was significantly less on collagens. No cytotoxic effects were observed with anti-beta 1 antibody or its fragments. These results suggest that antibodies to integrin matrix receptors on glomerular cells alter cell interactions with the glomerular basement membrane and lead to increased glomerular permeability to proteins via a process that is initiated by integrin cross-linking rather than through simple interference with cell adhesion per se.
Severity of beta-thalassemia due to genotypes involving the IVS-I-6 (T-->C) mutation.
Among individuals of Mediterranean or Middle Eastern descent, the IVS-I-6 (T-->C) mutation is one of the most common causes of beta-thalassemia. In this report, we describe the clinical phenotypes of a group of beta-thalassemia patients who are compound heterozygotes for the relatively mild IVS-I-6 (T-->C) beta-thalassemia mutation and more severe beta(+)- or beta (0)-thalassemia mutations. Although most of these patients are transfusion-dependent, the requirement for regular transfusions generally occurred late in childhood. A correlation between concomitant alpha-thalassemia and a mild transfusion-independent phenotype is not apparent, indicating the involvement of other ameliorating determinants.
Novel seventeen basepair deletion in exon 3 of the beta-globin gene.
Explore the source record for details and available documents.
Implementation of the CNS role in Vancouver, British Columbia, Canada.
The CNS as an advanced practitioner contributes significantly to the provision of comprehensive patient care services. Development and implementation of the CNS role are complex processes. This study was designed to describe the experience of practicing CNSs in various health care agencies in the Lower Mainland (the geographic region of British Columbia, Canada, comprising Vancouver and adjacent communities). Major themes emphasize the complex interplay of role ambiguity, organizational structure, and administrative support in facilitating and/or impeding the CNS role implementation process.
Identification of a new high oxygen affinity hemoglobin variant: Hb Aurora [beta 139(H17) Asn-->Tyr].
A 73-year-old female of Dutch descent was referred for investigation of a high oxygen affinity hemoglobin variant. The beta-globin gene was amplified using the polymerase chain reaction. Direct nucleotide sequencing of the polymerase chain reaction amplified DNA revealed that she is heterozygous for a novel beta-globin gene mutation at codon 139, AAT-->TAT. The resulting hemoglobin variant has been designated Hb Aurora [beta 139 (H17) Asn-->Tyr].
Identification of a novel termination codon mutation (TAA-->TAT, Term-->Tyr) in the alpha 2 globin gene of a Laotian girl with hemoglobin H disease.
Explore the source record for details and available documents.
Characterization of a highly polymorphic trinucleotide short tandem repeat within the human antithrombin gene.
Explore the source record for details and available documents.
Genetic linkage studies in antithrombin-deficient kindreds using a highly polymorphic trinucleotide short tandem repeat (STR) within the human antithrombin gene.
PCR amplification and analysis of short tandem repeats (STR) have provided a useful tool for genetic linkage studies and for the diagnosis of genetic disorders. We have recently identified a novel trinucleotide STR, (ATT).(TAA), in the fifth intron of the human antithrombin gene (AT3) located on chromosome 1q23. PCR amplification, cloning, and sequence analysis revealed this AT3-STR to be highly polymorphic with repeat units ranging in size from (ATT)5 to (ATT)18. Ten distinct alleles were found in 81 unrelated Caucasian individuals (162 alleles) with an observed heterozygosity of 81%. Genetic linkage studies using the AT3-STR in two previously described antithrombin (AT)-deficient kindreds, AT-Hamilton (Ala 382 Thr) and AT-Amiens (Arg 47 Cys), demonstrate, in a given kindred, that a specific AT3-STR polymorphism is strongly associated with a particular AT mutation. Thus, this highly polymorphic AT3-STR should be very useful in performing linkage studies in AT-deficient kindreds as well as in investigating other chromosome 1-related genetic disorders.
DNA diagnosis of Hb S and Hb Caribbean (alpha 2 beta 2 91 Leu-->Arg) in a Jamaican family.
We describe a Canadian infant of Jamaican descent who presented with mild anemia. Hb electrophoresis revealed Hb S and an unknown Hb variant that migrated slightly faster than Hb S on cellulose acetate. Molecular studies of the family indicated that the proband is a compound heterozygote for Hb S and Hb Caribbean. Hb Caribbean has previously been characterized as a mildly unstable hemoglobin with low oxygen affinity, due to a Leu-->Arg substitution at amino acid residue 91. The present study establishes the molecular basis for Hb Caribbean (beta 91, CTG-->CGG) and confirms that Hb S/Hb Caribbean syndrome is not associated with serious clinical manifestations.
Hb E/Hb LeporeHollandia in a family from Bangladesh.
We describe a family from Bangladesh in which three children are compound heterozygotes for Hb E (alpha 2 beta 2, beta 26Glu Lys) and Hb Lepore (delta-beta fusion gene). PCR amplification and direct nucleotide sequencing established that the fusion gene is Hb LeporeHollandia, with the cross-over localized to a 40 bp window between codon 22 and IVS-1 nt 16 of the delta- and beta-globin genes. This unusual combination of mutations is associated with a relatively mild clinical phenotype, with all three affected siblings having microcytic anemia of moderate severity without the need for transfusions.
Hb FM-Fort Ripley: confirmation of autosomal dominant inheritance and diagnosis by PCR and direct nucleotide sequencing.
We describe a normal neonate who presented at four days of age with asymptomatic cyanosis. There was no evidence of cardiac or pulmonary abnormality and an extended family history included 13 other affected family members with asymptomatic cyanosis lasting one to three months. Polymerase chain reaction (PCR) amplification and direct nucleotide sequencing of the proband's G gamma chain gene revealed the mutation at codon 92 (CAC-->TAC) previously shown in haemoglobin FM-Fort Ripley (alpha 2 gamma G gamma 92 (F8) His-->Tyr). This is the first family with Hb FM-Fort Ripley reported so far. It demonstrates autosomal dominant inheritance of this condition and incomplete penetrance.
Identification of a novel beta O-thalassaemia mutation in a Greek family and subsequent prenatal diagnosis.
We present a case in which a Greek couple was considered not to be at risk of having children with homozygous beta-thalassaemia, an assessment based largely on the father's belief that he carried alpha-thalassaemia. After their first child was diagnosed with homozygous beta-thalassaemia, the case was re-assessed and both parents were shown to have the haematological profile of beta-thalassaemia trait. Screening for the common Mediterranean mutations demonstrated that the mother carries the IVS-1 nt 110 G-->A beta(+)-thalassaemia mutation. Direct nucleotide sequencing of PCR-amplified DNA revealed that the father carries a novel beta O-thalassaemia mutation, frameshift codons 9/10 (+T). The couple's second pregnancy was terminated after prenatal testing revealed that the fetus had inherited both parental mutations. This case illustrates the need to confirm the carrier status of individuals prior to assessing their genetic risks, and highlights the importance of being able to identify rare or novel beta-thalassaemia mutations.
Trinucleotide repeat polymorphism within the human antithrombin gene (AT3): allele frequency data for three population groups.
The fifth intron of the human antithrombin gene (AT3) of chromosome 1q23 contains a highly polymorphic short tandem repeat based on the trinucleotide repeat [ATT]. Alleles range in size from [ATT]5 to [ATT]18, and can be typed using the polymerase chain reaction. Here we report allele frequency population data for Caucasians, Blacks and Southeast Asians. Statistical analyses demonstrate consistency with Hardy-Weinberg equilibrium for all three databases, and that the allele frequencies of all three population groups are significantly different from each other. This locus reveals 76% to 87% heterozygosity and therefore may be useful for forensic identity testing and paternity determination.