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Biomedical subjects

A J Ward

Publications and source records attributed to A J Ward.

At least 19 recordsLinked to original sources
PubMed1999

Mutation screening and genotype:phenotype correlation in familial hypercholesterolaemia.

The aim of this study was to develop a mutation screening protocol for familial hypercholesterolaemia (FH) patients and to assess genotype/phenotype effects in terms of pre-treatment lipid profiles and presentation of tendon xanthomata (TX). A total of 158 families with clinical definitions of possible (120) or definite (38) FH were studied using a tiered screening protocol. Mutations were identified in 52 families, 44 families showing 23 different LDLR gene defects and eight families showing the common Apo B100 gene defect R3500Q. LDLR defects were detected in various regions of the gene with 56% in the LDL binding domain (exons 2-6) and 37% in the EGF precursor homology domain (exons 7-14). The most common mutations were D461N(7), C210X(5), 932delA(5), and C163Y(4). Frameshift mutations accounted for 20% with nonsense 13%, mis-sense 35%, splice 3%, Apo B 13% and 2% large deletion, 13% of clinically definite FH remained undefined. In conclusion, DNA based diagnosis is possible in 79% (30/38) of clinically definite FH families and of the 120 possible FH families at the start of the screening program, 18% (22/120) now have defined mutations. Overall 60 families from the original 158 meet the clinical and/or genetic criteria for definite FH. Tendon xanthomata were present in only 58% (30/52) of genetically defined FH families, thus limiting its use as a strict diagnostic criteria. Families with low density lipoprotein receptor (LDLR) defects present with higher total and LDL cholesterol levels and a higher incidence of TX than do those with the common Apo B variant, and frameshift mutations appear to have the most severe presentation.

Electrophoresis, Agar Gel↗
PubMed1999

Familial defective apolipoprotein B-100 (R3500Q) in Northern Ireland.

Familial defective apolipoprotein B-100 (FDB) R3500Q is an autosomal co-dominant disorder caused by the substitution of glutamine for arginine at amino acid residue 3500 of the apolipoprotein B-100 gene. It is associated with hypercholesterolaemia of varying severity, and with coronary artery disease. Hypercholesterolaemic patients (n = 158) from Northern Ireland were screened for the defect by polymerase chain reaction-mediated, site-directed mutagenesis. Clinical presentation ranged from moderate hypercholesterolaemia with a family history of hypercholesterolaemia or heart disease (n = 104) to those classified as definitely having familial hypercholesterolaemia (FH) (n = 54). Eight (5.1%) unrelated individuals were found to be heterozygous for the FDB R3500Q mutation, including two (3.7%) of those 54 classified clinically as having FH. Treatment with HMG-CoA-reductase-inhibiting drugs (statins) decreased total cholesterol by 22-44% and low-density lipoprotein cholesterol by 34-46% in all but one FDB heterozygote.

Adolescent↗
PubMed1997

APO E genotype and familial hypercholesterolaemia.

Apolipoprotein E genotypes were measured in 83 patients with familial hypercholesterolaemia (FH) and in 175 blood donor controls. Following DNA extraction from peripheral blood, each sample was genotyped for the Apo E polymorphism by polymerase chain reaction. No significant differences were found in the levels of the epsilon 2 and epsilon 3 alleles between the two groups, while the epsilon 4 allele was approximately twice as prevalent in the FH patients as in controls (P = 0.006, df = 1). Of the FH patients, 8.4% were homozygous for the epsilon 4 allele while this genotype was rare in controls (P = 0.009, df = 1). These results suggest that the epsilon 4 allele is over represented in the FH population and may contribute to increased cholesterol levels and consequent vascular disease.

Adolescent↗
PubMed1996

Cytotoxic, nuclear, and growth inhibitory effects of photodynamic drugs on pancreatic carcinoma cells.

The light-activated drugs AlPcS4 and T4MPyP were studied in a pancreatic carcinoma cell line for their effects on DNA integrity, cell division, proliferation, and survival. The micronucleus assay measured nuclear changes and also the number of actively dividing cells while, under similar conditions, the MTT assay measured cell survival. When tumour cells were exposed to light, pre-treatment with AlPcS4 induced more micronuclei than did T4MPyP at the same levels of cell division and survival. Both drugs showed a correlation between phototoxicity and changes to DNA integrity so establishing micronuclei formation as an important indicator of photodynamic drug action on tumour cells.

Animals↗
PubMed1996

Reconstruction femoral nailing for nonunion of subtrochanteric fracture: a revision technique following dynamic condylar screw failure.

We report two cases of nonunion of subtrochanteric fractures associated with failure of fixation with a dynamic condylar screw (DCS) due to plate fracture. In both cases the nonunion was successfully treated by insertion of a reconstruction femoral nail. This implant allowed early weightbearing despite the patients' advanced age and poor bone quality. We did not perform direct bone grafting and the fractures healed without complication.

Aged↗
PubMed1996

Pathological fracture after prophylactic reconstruction nailing of the femur. The need for distal locking.

Reconstruction nails have become the treatment of choice for established or impending subtrochanteric fractures of the femur and distal locking is said not to be indicated if the isthmus is intact. We report a case where distal locking was not performed and a proximal fracture subsequently occurred. We believe that distal locking should always be carried out in impending subtrochanteric fractures which are treated by nailing.

Femoral Neoplasms↗
PubMed1996

A novel single base deletion in the LDLR gene (211delG): Effect on serum lipid profiles and the influence of other genetic polymorphisms in the ACE, APOE and APOB genes.

A single base deletion (211delG) in the low density lipoprotein receptor (LDLR) gene was shown to cause familial hypercholesterolaemia (FH) in a large family from Northern Ireland. Twenty-four of 52 family members tested had this mutation, 13 of which were newly diagnosed. Mutation-positive individuals had significantly higher mean total-cholesterol (TC) and LDL-cholesterol (LDL-C) than those without 211delG. LDL-C was a more accurate indicator of disease status than TC. When TC levels alone were considered, in individuals over 16 years, a false negative rate (TC < 7.5 mmol/l) of 40% was found; however this fell to 13% based on inclusion of LDL-C levels. Individuals with coronary artery disease (CAD) had significantly higher TC levels than those without CAD and tended to have tendinous xanthomas (TX) and corneal arcus (CA). Generic polymorphisms in the angiotensin converting enzyme (ACE) and apolipoprotein (apo) B genes did not appear to be associated with lipid levels or with the clinical severity of the disease; however, the apo E epsilon4 allele did show a lipid-raising effect in individuals with the mutation.

Adolescent↗
PubMed1995

Recruiting minorities into clinical trials: toward a participant-friendly system.

The purpose of this review is to describe the state of the art in recruiting participants for clinical trials designed to test new methods of treatment or disease prevention. The ultimate objective of this review is to provide a summary of key issues in recruiting diverse populations into clinical trials, particularly ethnic and racial minorities. An overview of general issues related to clinical trial participation is followed by a detailed discussion of specific issues that must be addressed by investigators as they recruit minority populations for clinical trial. To date, the majority of clinical trials have included a limited segment of the U.S. population: middle-class, married white males. These trials have faced many problems in their efforts to recruit participants, including barriers to physician participation, barriers to subject participation, barriers to planning and implementing effective recruitment strategies, and costs of the recruitment phase of clinical trials. Following this general introduction is a discussion of the definition of diverse populations. The first step investigators must take as they prepare to recruit study participants is to develop a relevant definition of the subject populations. A detailed review of investigators' experiences in recruiting minorities into clinical trials is presented, including barriers to minority recruitment, barriers inherent in study design, researcher bias, barriers to minority physician participation, as well as strategies for minority recruitment, modifications of study design, and cost issues. Formal evaluation of recruitment strategies has been limited. Most investigators present descriptive reports of their experience in recruiting diverse populations into clinical trials. Research into the issues presented and rigorous testing of specific strategies is needed. A series of steps that are essential to effective clinical trials recruitment of diverse populations is presented.

Clinical Trials as Topic↗
PubMed1994

Inflammation, chromosomal instability, and cancer: the schistosomiasis model.

Evidence is accumulating in support of a role for reactive oxygen species in the etiology of cancer. Inflammatory cells, such as neutrophils, macrophages, and eosinophils, are an important endogenous source of oxygen radicals. Stimulation of these cells by tumor promoters or by foreign bodies (parasites, bacteria, etc.) causes the release of reactive oxygen species. Laboratory studies have shown that genetic damage and neoplastic transformation are induced in vitro in cells cocultured with activated inflammatory cells. We have recently begun to study the role of inflammatory reactions in inducing genetic damage in a human population. This paper describes our initial studies of Egyptian patients infected with Schistosoma haematobium. This infection induces chronic inflammation and irritation in the urinary bladder and is associated with increased cancer at this site. We describe a recently completed population study that shows that infected individuals have elevated levels of genetic damage in their bladders, as measured by the exfoliated cell micronucleus test. Treatment that kills the parasite also reduces the micronucleus frequencies. We also explore the hypothesis that altered sensitivity of clones of cells in these patients to reactive oxygen species could be a force that drives the development of neoplasia by facilitating clonal expansion. Evidence is presented for the possible involvement of loci on chromosome 11 in controlling the level of chromosomal breakage caused by oxidative damage. We have shown that bladder carcinoma cells are sensitive to micronucleus induction by promoter-activated neutrophils and that they can be protected from this damage by insertion of a normal chromosome 11. Further work is in progress to define the source of chromosomal breakage in schistosomiasis patients and to begin to develop an understanding of the host factors protecting bladder cells in these individuals from genetic damage.

Chromosome Aberrations↗
PubMed1994

Involvement of inflammatory reactions and elevated cell proliferation in the development of bladder cancer in schistosomiasis patients.

Schistosoma haematobium infection is strongly associated with urinary bladder cancer. Although numerous explanations have been proposed for this association, the nature of this relationship remains unresolved. This paper explores the hypothesis that inflammation and elevated cell proliferation play a major role in the development of bladder cancer in infected patients, possibly by increasing the level of genetic instability in the urothelium. The paper details in vivo and in vitro studies being done in our laboratories to test this hypothesis. These studies include population studies in which chromosomal breakage in the bladder of infected individuals is assayed using the micronucleus (MN) test on exfoliated urothelial cells. The approach also includes parallel studies in Vancouver with patients with long-term catheter drainage, a population with many similarities to schistosomiasis patients. In the in vitro studies we are co-incubating bladder cells with activated neutrophils or experimental conditions simulating inflammation. These studies show that inflammatory cells when activated can induce micronuclei in bladder cells and that this response is associated with loci on chromosome 11, a chromosome commonly altered during bladder carcinogenesis. A final approach being used is to assay chromosomal change (MN frequencies and numerical chromosome alterations) and level of proliferation (expression of proliferating cell nuclear antigen) in archival biopsies from schistosomiasis patients. Preliminary results show that a dysregulation of cell proliferation is occurring during cystitis in these patients. The extent to which this alteration affects the level of chromosomal breakage is yet to be determined.

Cell Division↗
PubMed1994

Response of fibroblast cultures from ataxia-telangiectasia patients to reactive oxygen species generated during inflammatory reactions.

Cells from patients with ataxia-telangiectasia (AT) are more sensitive than cells from normal individuals to a number of compounds which induce DNA damage via oxygen-derived free radical attack. We tested the hypothesis that AT cells would show a sensitivity to reactive oxygen species (ROS) generated by activated inflammatory cells. AT cells were exposed to neutrophils activated with 12-O-tetradecanoyl-phorbol-13-acetate (TPA) or to xanthine/xanthine oxidase (X/XO), an enzyme system which generates superoxide and hydrogen peroxide. Induced micronuclei (MN) frequencies (corrected for spontaneous MN frequencies) were significantly higher in AT cell cultures than in cultures from normal individuals (comparison of MN frequencies of AT vs. normal cultures: for treatment with activated neutrophils, P = 0.003; for X/XO, P = 0.05). The comet assay was used to determine whether the elevated chromosomal damage in the treated AT cells was due to a difference in strand breakage or its rejoining. X/XO treatment was used in studies of single-stranded (SS) DNA breakage, and X-ray treatment for double-stranded (DS) DNA damage. AT and normal cells showed no significant differences in the initial levels of SS (P = 0.29) or DS (P = 0.91) DNA damage. Likewise, they exhibited similar rejoining kinetics (rejoining half-time for SS = 10 min, for DS = 30 min). These data support the involvement of the AT loci in determining a cell's ability to deal with oxidative stress, although the mechanism underlying this effect has yet to be resolved. The data also suggest that AT patients are at elevated risk of sustaining DNA damage in tissues undergoing inflammatory reactions.

Ataxia Telangiectasia↗
PubMed1994

Bronchial responsiveness is not always increased after allergen challenge.

Increased bronchial responsiveness has been reported at various time points following allergen challenge (AC), and may be related to the magnitude of the late response (LAR). We have studied 20 mild asthmatics, who were known to develop a late asthmatic response to inhalation of house dust mite extract (fall of > 15% from post-diluent baseline FEV1 from 2 to 7h after AC). The provocation concentration of methacholine causing a 20% fall in FEV1 (PC20 FEV1) was measured before and 24 h after challenge with house dust mite extract (HDM). The mean (SEM) change in log(PC20) was 0.08 (0.09) mg ml-1, and was not significant (P = 0.38; paired t-test). The change in PC20 for each subject was not significantly correlated with the size of LAR (r = -0.33; P > 0.05), but was significantly correlated with the absolute change from baseline FEV1 at 24 h (r = 0.67; P < 0.01). Our subjects had a high baseline responsiveness, when compared with previous studies. We suggest they may have been approaching a maximally responsive state prior to study, and allergen challenge may have had little effect in further increasing responsiveness. Exposure to allergen in late responders is not necessarily followed by an increase in non-specific bronchial responsiveness.

Adolescent↗
PubMed1994

A protective effect of chromosome 11 against DNA damage by TPA-activated neutrophils but not TPA acting alone.

Evidence from animal models suggests that 12-O-tetrade-canoylphorbol-13-acetate (TPA) is capable of inducing genetic damage within a tissue, although the mechanism underlying this response is unknown. A favoured hypothesis is that the TPA is acting either by stimulating cells in the tissue directly to generate DNA damaging agents or by recruiting inflammatory cells to the tissue and stimulating them to release such agents. These agents include reactive oxygen species, such as hydrogen peroxide and superoxide anion, as well as products generated during lipid peroxidation and arachidonic acid metabolism. It is not known whether significant alterations occur in the sensitivity of cells to TPA during the process of tumourigenesis. In this paper the capacity of TPA to induce chromosomal breakage (measured by micronuclei induction) was found to be elevated in bladder tumour cell lines compared to two normal cultures, a primary epithelial culture and a fibroblast culture. This effect was observed when cells were exposed to TPA directly or co-cultured with TPA-activated neutrophils isolated from human blood. In addition, we present evidence that loci on chromosome 11 may be involved in altering the response of cells to TPA. When chromosome 11 was inserted into a bladder tumour cell line, a reduction in sensitivity to TPA-activated neutrophils was observed. The chromosome insert did not protect against damage induced by direct treatment with TPA alone. In another scenario, fibroblasts from a patient with ataxia telangiectasia, a syndrome localized to chromosome 11, were shown to have an elevated sensitivity to the chromosome damaging action of TPA-activated neutrophils, but not to TPA alone. These results suggest that some of the alterations occurring in a tissue during tumourigenesis could have a significant impact on the responsiveness of cells to genetic damage by TPA. They also suggest that the damage induced by TPA in a cell may be different if a neutrophil is present.

Ataxia Telangiectasia↗
PubMed1993

Post-traumatic osteoporosis and algodystrophy after external fixation of tibial fractures.

The incidence of two forms of post-traumatic osteoporosis and algodystrophy in the ankle region of 20 patients with displaced diaphyseal fractures of the tibia treated with external fixation were studied. Acute localised osteoporosis (ALO) occurred in 14 (70 per cent) and 5 (25 per cent) developed algodystrophy. ALO was significantly less frequent in matched patients treated by internal fixation or by external plaster-of-Paris (POP) cast. Regional osteoporosis (RO) was most common in POP patients. The presence of ALO may indicate the development of algodystrophy following tibial fracture. Our findings suggest that external fixation may predispose to ALO and algodystrophy.

Acute Disease↗
PubMed1993

A sensitivity to oxidative stress is linked to chromosome 11 but is not due to a difference in single strand DNA breakage or repair.

Defects in loci on chromosome 11 have been associated with tumourigenicity, anchorage-independent growth, metastasis and radiosensitive DNA repair in tumour cells. The introduction of normal chromosome 11 into these cells suppresses these responses. In the present study we tested two hypotheses: (1) that microcell fusion of normal chromosome 11 into bladder-carcinoma cells (A1698) can protect the cells against chromosomal damage by oxidative stress; and (2) that insertion of normal chromosome 11 corrects a single-strand (SS) DNA-repair defect. Cultures of A1698 (termed parent) and its microcell-mediated hybrid (termed hybrid) were exposed for 1 h to xanthine/xanthine oxidase (X/XO) or co-incubated with human neutrophils activated with 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Micronucleus frequencies (an indication of chromosomal damage) were significantly higher in parent cultures after treatment than in hybrid (P < 0.0001). The level of single-strand DNA breakage and its repair was assayed in X/XO-treated cultures with the alkaline comet assay. There was no significant difference between parent and hybrid in the amount of SS DNA breakage at treatment (P > 0.1) or after 20 min of repair (P > 0.1). The data support the involvement of a defect in chromosome 11 leading to sensitivity to oxidative stress and suggest this defect is not in the initial amount or rate of rejoining of SS DNA breakage.

Cell Line↗
PubMed1993

Theophylline--an immunomodulatory role in asthma?

Theophylline, a drug used for the treatment of asthma, is recognized as an immunomodulator affecting T-lymphocytes both in vitro and in vivo. The effect of slow-release theophylline (Uniphyllin Continus) on the late asthmatic response (LAR) has been compared with placebo before and after 5 wk of treatment in a double-blind, randomized, parallel group study. Nineteen volunteers with stable mild asthma successfully completed the study. All were dual responders with a documented late response to inhaled house dust mite extract. The LAR was assessed both in terms of changes in lung function and in peripheral blood T-lymphocyte subsets. The mean (SEM) maximal late fall in FEV1 before and after treatment was 28.8 (4.1)% and 7.8 (2.0)% with theophylline, versus 35.8 (5.1)% and 29.1 (5.0)% with placebo (p = 0.046; Cl, 0.3-26.9). Corresponding figures for specific airway conductance (SGaw) were 46.4 (8.4)% and 7.2 (8.0)% with theophylline versus 46.2 (7.2)% and 44.8 (7.7)% with placebo (p = 0.008; Cl, 11.2 to 64.1). This was achieved at a mean (SD) trough serum theophylline level of only 7.8 (3.5) micrograms/ml. Airway responsiveness to methacholine was not significantly changed 24 h after the initial allergen challenge. There was a trend towards a decrease in baseline responsiveness after treatment with theophylline compared with that after placebo (p = 0.07). Studies of peripheral blood lymphocytes showed a modifying effect of treatment on the allergen-induced changes in CD4 and CD8 counts 48 h after challenge. Previous studies have shown a protective effect of theophylline on the LAR at serum theophylline concentrations within the conventional range for bronchodilation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adjuvants, Immunologic↗