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Biomedical subjects

Brian Ward

Publications and source records attributed to Brian Ward.

9 recordsLinked to original sources
PubMed2007

A retrospective, case-control pilot study of the natural history of pediatric gastroesophageal reflux.

The duration of gastroesophageal reflux disease (GERD) is an important factor in the development of esophageal complications. The objective of this study was to examine in a retrospective, case-controlled manner the prevalence of GERD in adults who were diagnosed with GERD in infancy or early childhood. Infants and children with nonsyndromic GERD diagnosed by an experienced pediatric gastroenterologist from 1976 to 1980 and control subjects seen for well-child care from 1980 to 1985 were included in this study. The subjects were located and contacted by telephone or mail and administered a brief structured questionnaire relating to their current history of GERD. GERD-A was defined as weekly heartburn or regurgitation of any severity, and GERD-B was defined as monthly heartburn or regurgitation greater than mild in severity. Sixty-five participants (31 patients and 34 controls) returned completed questionnaires and were subdivided into the three study groups as follows: Infant (15), Child (16), and Control (34). The prevalence of adulthood GERD-A was 13, 31, and 21% in the Infant, Child, and Control groups, respectively. Similarly, the prevalence of adulthood GERD-B was 20%, 44%, and 24%, respectively. The Child group tended to report more severe heartburn than the other groups. The Infant group tended to report more frequent regurgitation, and the Child group also reported a higher prevalence of nocturnal heartburn and more frequent use of GERD medications, although these were not statistically significant. These data suggest that pediatric GER is a heterogeneous disorder and that GERD occurring after infancy may be more predictive of the presence of GERD during adulthood. Longitudinal follow-up of a larger number of children is needed to answer the question of when classic adulthood GERD begins.

Adolescent↗
PubMed2006

Prediction of MLH1 and MSH2 mutations in Lynch syndrome.

CONTEXT: Lynch syndrome is caused primarily by mutations in the mismatch repair genes MLH1 and MSH2. OBJECTIVES: To analyze MLH1/MSH2 mutation prevalence in a large cohort of patients undergoing genetic testing and to develop a clinical model to predict the likelihood of finding a mutation in at-risk patients. DESIGN, SETTING, AND PARTICIPANTS: Personal and family history were obtained for 1914 unrelated probands who submitted blood samples starting in the year 2000 for full gene sequencing of MLH1/MSH2. Genetic analysis was performed using a combination of sequence analysis and Southern blotting. A multivariable model was developed using logistic regression in an initial cohort of 898 individuals and subsequently prospectively validated in 1016 patients. The complex model that we have named PREMM(1,2) (Prediction of Mutations in MLH1 and MSH2) was developed into a Web-based tool that incorporates personal and family history of cancer and adenomas. MAIN OUTCOME MEASURE: Deleterious mutations in MLH1/MSH2 genes. RESULTS: Overall, 14.5% of the probands (130/898) carried a pathogenic mutation (MLH1, 6.5%; MSH2, 8.0%) in the development cohort and 15.3% (155/1016) in the validation cohort, with 42 (27%) of the latter being large rearrangements. Strong predictors of mutations included proband characteristics (presence of colorectal cancer, especially > or =2 separate diagnoses, or endometrial cancer) and family history (especially the number of first-degree relatives with colorectal or endometrial cancer). Age at diagnosis was particularly important for colorectal cancer. The multivariable model discriminated well at external validation, with an area under the receiver operating characteristic curve of 0.80 (95% confidence interval, 0.76-0.84). CONCLUSIONS: Personal and family history characteristics can accurately predict the outcome of genetic testing in a large population at risk of Lynch syndrome. The PREMM(1,2) model provides clinicians with an objective, easy-to-use tool to estimate the likelihood of finding mutations in the MLH1/MSH2 genes and may guide the strategy for molecular evaluation.

Adaptor Proteins, Signal Transducing↗
PubMed2006

Development of a genetic assay to distinguish between Leishmania viannia species on the basis of isoenzyme differences.

BACKGROUND: Tegumentary leishmaniasis in Latin America is caused mainly by Leishmania viannia braziliensis complex parasites. L. braziliensis and Leishmania viannia peruviana are the 2 predominant Leishmania species in Peru. L. braziliensis is more virulent, because it can cause mucocutaneous leishmaniasis, known as espundia, that results in severe facial destruction. Early identification of the species that causes the initial cutaneous infection would greatly help to prevent mucocutaneous leishmaniasis, because it would allow more aggressive treatment and follow-up. However, because of the close genetic similarity of L. braziliensis and L. peruviana, there currently exists no simple assay to distinguish between these species. METHODS: We cloned the mannose phosphate isomerase gene from both L. braziliensis and L. peruviana. It is the only known isoenzyme capable of differentiating between L. braziliensis and L. peruviana in multilocus enzyme electrophoresis. Interestingly, only a single nucleotide polymorphism was found between the mannose phosphate isomerase genes from L. braziliensis and L. peruviana, resulting in an amino acid change from threonine to arginine at amino acid 361. A polymerase chain reaction assay was developed to distinguish the single nucleotide polymorphism of the mannose phosphate isomerase gene to allow for the specific identification of L. braziliensis or L. peruviana. RESULTS: This assay was validated with 31 reference strains that were previously typed by multilocus enzyme electrophoresis, successfully applied to patient biopsy samples, and adapted to a real-time polymerase chain reaction assay. CONCLUSIONS: This innovative approach combines new genetic knowledge with traditional biochemical fundamentals of multilocus enzyme electrophoresis to better manage leishmaniasis in Latin America.

Amino Acid Sequence↗
PubMed2005

Canadian Association for Immunization Research and Evaluation (CAIRE) guidelines for industry-sponsored clinical trial and epidemiology contract research.

In response to concerns about interactions of academic and public health investigators with industry, the Canadian Association for Immunization Research and Evaluation (CAIRE), in collaboration with six major vaccine manufacturers, developed guidelines for participation in industry-sponsored clinical trial and epidemiology contract research within Canada. Topics addressed include definition of investigators, data ownership, protocol development, data management, data analysis, producing a study report and publication of the results of the study.

Canada↗
PubMed2002

HLA-G exhibits low level of polymorphism in indigenous East Africans.

Human leukocyte antigen G (HLA-G) is a nonclassical HLA class I antigen that is predominantly expressed on invasive cytotrophoblastic cells, and is postulated to be a mediator of maternal-fetal tolerance. Almost all studies in Caucasian and Asian populations have consistently reported that HLA-G exhibits low levels of allelic polymorphism unlike the classical class I genes. However, the concept that HLA-G is nonpolymorphic has recently been challenged in a single study of African-American subjects. We have examined the DNA sequences of the first seven HLA-G exons by single-strand conformational polymorphism (SSCP) and DNA direct sequencing procedures in 45 healthy individuals from an indigenous African population. Overall, we detected 14 sequence variations: 3 in the signal peptide (exon 1); 2 in the alpha-1 domain (exon 2); 5 in the alpha-2 domain (exon 3); 2 in alpha-3 domain (exon 4); 2 in transmembrane domain (exon 5); and none in the cytoplasmic tail (exons 6 and 7). Of these variants, only three result in amino acid substitutions at the protein level. Of particular interest, we identified a novel nucleotide substitution (C727T), 56 bp before the HLA-G gene transcription start site, located in the putative binding site for polyomavirus enhancer-binding protein 2 (PEBP2) transcriptor factor. These data confirm previous reports describing HLA-G exhibiting limited allelic polymorphism. Further studies are needed to determine the impact of the C727T polymorphism on the level or developmental regulation of HLA-G expression.

Africa, Eastern↗
PubMed2002

Exploring ligand-DNA space using type IIS restriction enzymes.

Investigating ligand-DNA interactions using type IIS restriction enzymes (IISRE) as footprinting reagents is reviewed and contemplated. Ligand binding at a IISRE's cleavage but not sequence recognition site protects DNA from strand scission. This spatial arrangement has been exploited in the development of qualitative (combinatorial) and quantitative ligand-DNA investigative methods collectively termed Type IIS Restriction Enzyme Footprinting (cIISREF and qIISREF respectively). In cIISREF, the consensus binding sequence of a ligand is sought by using a IISRE to segregate combinatorial library members that are bound by ligand from those that are not. A PCR is performed following the segregation step to enrich the library in ligand binding (i.e. uncut) sequences. It might be possible that diversities approaching 10(30) unique sequences could be simultaneously searched using this homogeneous and biologically relevant method. For qIISREF, a ligand-DNA equilibrium constant is measured by quantifying the amounts of target and control DNA IISRE cleavage products as a function of ligand concentration. The control sequence is engineered to not bind ligand. Along with illustrating these methods by reviewing published works, current concerns and future prospects for IISREF are discussed.

Base Sequence↗