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Biomedical subjects

M A Mendall

Publications and source records attributed to M A Mendall.

At least 19 recordsLinked to original sources
PubMed2006

Systematic review: adipose tissue, obesity and gastrointestinal diseases.

BACKGROUND: Obesity is increasingly being recognized as a risk factor for a number of benign and malignant gastrointestinal conditions. However, literature on the underlying pathophysiological mechanisms is sparse and ambiguous. Insulin resistance is the most widely accepted link between obesity and disease, particularly colorectal cancer. The recognition that intra-abdominal fat is immunologically active sheds new light not only on the pathogenesis of obesity-related gastrointestinal conditions, but also on inflammatory conditions such as Crohn's disease. AIM: To describe the biology of adipose tissue, its impact on the immune system and explores the possible underlying mechanisms linking obesity to gastrointestinal diseases. It also looks at the role of mesenteric fat in determining severity and course of Crohn's disease. METHODS: Relevant English-language literature and abstracts cited on MEDLINE database were reviewed. RESULTS: Our recent finding of an association between obesity and subclinical bowel inflammation suggests that, apart from promoting generalized immune activation, fat also evokes local immune responses. We propose that the proinflammatory milieu promoted by obesity could underlie many of these associations and that the mechanism implicating insulin resistance may merely represent an epiphenomenon. In Crohn's disease, on the other hand, intra-abdominal fat may provide a protective mechanism. CONCLUSION: The potential of adipose tissue as a therapeutic target is vast and needs exploration.

Adipose Tissue↗
PubMed2002

Review article: faecal markers in the assessment of activity in inflammatory bowel disease.

The fundamental pathological process behind ulcerative colitis and Crohn's disease is intestinal inflammation. As the precise cause of this is not yet completely understood, current treatment strategies are aimed at reducing or eliminating the inflammation. Endoscopic examination and histological analysis of biopsy specimens remain the 'gold standard' methods for detecting and quantifying bowel inflammation; however, these techniques are costly, invasive, and repeated examinations are unpopular with patients. Disease activity questionnaires and laboratory 'inflammatory markers', although widely used, show an unreliable correlation with endoscopy and histology. New markers need to be developed to detect and quantify bowel inflammation. These would be of use diagnostically and also an aid to pharmacological treatment.

Biomarkers↗
PubMed2002

Antibiotics increase functional abdominal symptoms.

OBJECTIVES: Data suggest that subjects with irritable bowel syndrome are more likely to report a recent course of antibiotics. This study tests the hypothesis that a course of antibiotics is a risk factor for an increase in the number of functional bowel complaints over a 4-month period in a general population sample. METHODS: We initiated a prospective case-control study in three general practices in South London. Consecutive patients aged 16-49 attending their general practitioner with non-GI complaints and given a prescription for antibiotics were invited to participate. Comparison subjects who had not had antibiotics for 1 yr were identified from the practice records by age group, gender, and previous general practitioner visits. Fifty-eight antibiotic and 65 control patients agreed to participate. Questionnaires covering demographic, GI, and psychological data were sent at recruitment and at 4 months. Seventy-four percent of subjects completed the study. The number of symptoms at follow-up compared to that at recruitment. RESULTS: Twenty of 42 antibiotic subjects (48%) versus 11/49 control subjects (22%) demonstrated one or more additional functional bowel symptoms at 4 months (unadjusted odds ratio = 3.14 [1.27-7.75]) (chi2 = 6.4, p = 0.01). Ten of 42 antibiotic subjects (24%) versus 3/49 control subjects (6%) demonstrated two or more additional functional bowel symptoms at 4 months (unadjusted odds ratio = 4.79 [1.22-18.80]) (chi2 = 5.8, p = 0.02). CONCLUSIONS: Functional bowel symptoms come and go, but subjects who are given a course of antibiotics are more than three times as likely to report more bowel symptoms 4 months later than controls.

Adolescent↗
PubMed2001

Ischaemic heart disease and Cag A strains of Helicobacter pylori in the Caerphilly heart disease study.

OBJECTIVE: To look for the presence of the more virulent strains of Helicobacter pylori (H pylori) in men who developed ischaemic heart disease over a 10 year period and in controls. DESIGN: The Caerphilly prospective heart disease study recruited 2512 men aged 45-59 years during 1979-83. Western blot analysis or enzyme linked immunosorbent assay (ELISA) was performed on serum taken from those who subsequently died of ischaemic heart disease, or developed non-fatal myocardial infarction, to determine H pylori and Cag A status. Similar information was available on age matched controls. RESULTS: During the first decade of the study, 312 men died of ischaemic heart disease or developed non-fatal myocardial infarction. Serum was available from 172 of these (55%). There was no evidence of an association between Cag A seropositivity and incident ischaemic heart disease or ischaemic heart disease mortality, either before or after adjustment for potential confounders (adjusted odds ratios 1.18 (95% confidence interval (CI) 0.76 to 1.85) and 1.13 (95% CI 0.61 to 2.07), respectively). Further, the odds ratios for ischaemic heart disease incidence and ischaemic heart disease mortality by H pylori seropositivity did not appear to depend on the presence or absence of Cag A strains (p = 0.76 and 0.77, respectively). CONCLUSIONS: In this cohort of middle aged men, followed over a 10 year period, there is little evidence of an association between Cag A seropositivity and either incident ischaemic heart disease or ischaemic heart disease mortality.

Antigens, Bacterial↗
PubMed2000

C-reactive protein concentration in children: relationship to adiposity and other cardiovascular risk factors.

Whether or not C-reactive protein (CRP) predicts heart disease in adults because it is a marker of damage or atherosclerosis is difficult to assess. In children, there is no confounding with coronary disease or active smoking. We measured CRP in 699 children aged 10-11 years. CRP levels were 47% higher in girls than boys, and rose with age by 15%/year. CRP levels were 270% (95% CI, 155-439%) higher in the top fifth than the bottom fifth of Ponderal index (weight/height(3)). After adjustment, CRP levels remained 104% (95% CI, 23-236%) higher in the 56 children of South Asian origin. CRP was unrelated to: birth weight, height, social class, Helicobacter pylori infection or passive smoke exposure. CRP was correlated with several cardiovascular risk factors, but only fibrinogen (r = 0.33, P = 0.0001), HDL-cholesterol (r = -0.13, P = 0.0006), heart rate (r = 0.12, P = 0.002) and systolic blood pressure (r = 0.08, P = 0.02) remained statistically significant after adjustment. We conclude that adiposity is the major determinant of CRP levels in children while physical fitness has a small independent effect. The strong relationships with fibrinogen and HDL-cholesterol suggest a role for inflammation throughout life in the development of atherosclerosis and cardiovascular disease. Longitudinal studies are needed to determine whether these associations reflect long term elevations of these risk factors in some individuals, or short term fluctuations in different individuals.

Age Distribution↗
PubMed2000

C-reactive protein: relation to total mortality, cardiovascular mortality and cardiovascular risk factors in men.

BACKGROUND: There is much interest in reported associations between serum C-reactive protein and incident ischaemic heart disease. It is uncertain what this association represents. We aimed to assess the effect of confounding from a number of different sources in the Caerphilly Prospective Heart Disease Study and in particular whether the low grade inflammation indicated by C-reactive protein may be the mechanism whereby non-circulating risk factors may influence pathogenesis of ischaemic heart disease. METHODS: Plasma specimens collected during 1979-83 from 1395 men with sufficient sample remaining were assayed for serum C-reactive protein by ELISA. Subsequent mortality and incident ischaemic heart disease events were ascertained from death certificates, hospital records and electrocardiographic changes at 5-yearly follow-up examinations. RESULTS: There was a positive association between C-reactive protein and incident ischaemic heart disease (P<0.005) mainly with fatal disease (P<0.002). There was also a positive association with all-cause mortality (P<0.0001). C-reactive protein was significantly associated with a number of non-circulating risk factors including body mass index (P<0.0001), smoking (P<0.0001), low forced expiratory volume in 1 s (P<0.0001), height (P=0.025), low childhood social class (P=0.014) and age (P=0.036). C-reactive protein was also associated positively with circulating risk factors including viscosity, leukocyte count, fibrinogen (all P<0.0001) and insulin (P=0.0058). After adjustment for non-circulating risk factors the association with all-incident ischaemic heart disease and ischaemic heart disease death became non-significant, but the association with all-cause mortality remained (P=0.033). Further adjustment for fibrinogen however removed any hint of an increasing trend in odds for all three outcomes. CONCLUSION: C-reactive protein levels are raised in association with a variety of established cardiovascular risk factors. Neither C-reactive protein nor the systemic inflammation it represents appears to play a direct role in the development of ischaemic heart disease.

Biomarkers↗
PubMed2000

Western blotting is useful in the salivary diagnosis of Helicobacter pylori infection.

BACKGROUND: The salivary diagnosis of Helicobacter pylori infection offers attractive possibilities for the epidemiological study of infection in children. Salivary enzyme linked immunosorbent assay (ELISA) is less reliable then serum ELISA, owing to variable transudation of immunoglobulin. In addition, children are more difficult to study because of lower specific serum antibody concentrations to H pylori. The performance of salivary western blotting in comparison with serum western blotting and serum ELISA was investigated in school children. SUBJECTS AND METHODS: Paired serum and saliva specimens were obtained from 669 [corrected] school children aged 9-11 in 10 British towns. All saliva and serum specimens were first analysed by ELISA; subsequently, western blotting of both specimens was performed on 31 and 34 specimens, respectively, to establish the criteria for positivity for western blotting. The remaining 121 specimens were then tested blindly and saliva was compared with the serum. RESULTS: The sensitivity and specificity of salivary ELISA in the 669 [corrected] specimens was 32 of 50 (64%) and 530 of 619 (86%) [corrected], respectively, when compared with serum ELISA. The western blotting validation was performed on 28 subjects with positive serum and positive salivary ELISA, 28 saliva positives with negative serum, 16 saliva negatives with positive serum, and 50 doubly negative subjects. Compared with serum western blots, the sensitivity and specificity of salivary western blots was 38 of 47 (81%) and 68 of 75 (91%), respectively. Using serum ELISA as the gold standard, the sensitivity and specificity were 32 of 44 (73%) and 72 of 78 (92%), respectively, the specificity being significantly higher than salivary ELISA (p < 0.001). CONCLUSION: Salivary western blotting for IgG is useful in the diagnosis of H pylori infection and is superior to ELISA. It also permits the identification of pathogenic strains.

Blotting, Western↗
PubMed1999

Chlamydia pneumoniae infection and early asymptomatic carotid atherosclerosis.

BACKGROUND: Chronic Chlamydia pneumoniae infection has been implicated in the pathogenesis of atherosclerosis but whether it plays a role at an early stage in the disease is uncertain. An early estimate of atherosclerosis can be obtained by ultrasonic imaging of the carotid artery to determine intima-media thickness (IMT) and the thickness of any atheroma plaques. METHODS AND RESULTS: In 983 normal population individuals aged 30 to 70 years, we measured common carotid artery (CCA) and carotid bulb IMT, and also carotid plaque thickness and the degree of internal carotid artery (ICA) stenosis. C. pneumoniae IgA titers of >/=16 and IgG titers of >/=64 were taken as positive. There was no association between C. pneumoniae IgA or IgG seropositivity with right, left, or mean CCA or bulb IMT, or with the presence of carotid plaques. There was a significant association between IgA seropositivity and >50% mean carotid stenosis with an odds ratio of 5.24 (95% CI 1.24 to 22.21, P=0.0245) after controlling for age and sex; after controlling for other cardiovascular risk factors, this was not significant 3.96 (95% CI 0. 84 to 18.78, P=0.082). No association was found between IgA or IgG seropositivity and markers of fibrinogen, log C-reactive protein, or leukocyte count. CONCLUSIONS: We found no evidence that serological evidence of C. pneumoniae infection is associated with early atherosclerosis. It is possible that IgA seropositivity is associated with more advanced disease but this hypothesis needs to be examined in a population with a higher prevalence of advanced atherosclerosis. We found no evidence that C. pneumoniae results in a chronic systemic inflammatory state.

Adult↗
PubMed1999

Relation of Chlamydia pneumoniae serology to mortality and incidence of ischaemic heart disease over 13 years in the caerphilly prospective heart disease study.

OBJECTIVES: To investigate the effect of Chlamydia pneumoniae infection on future development of ischaemic heart disease and mortality. DESIGN: Prospective longitudinal study. SETTING: Caerphilly, South Wales. SUBJECTS: Plasma specimens were collected during 1979-83 from 1773 men aged 45-59 years. These were tested for IgG and IgA antibodies to C pneumoniae (TW183) by microimmunofluorescence. OUTCOME MEASURES: 13 year mortality and incident ischaemic heart disease events were ascertained from death certificates, hospital records, and electrocardiographic changes at follow up every 4 to 5 years. RESULTS: 642 men (36.2%) had IgG antibodies at a titre of >/=1 in 16, of whom 362 (20.4% of all men) also had detectable IgA antibodies. The prevalence of ischaemic heart disease (a history of past or current disease) at entry was similar at all IgG antibody titres but was positively related to IgA antibody titre. IgA antibody titre was positively correlated with plasma viscosity but not with other cardiovascular risk factors. Incidence of ischaemic heart disease was not associated with either IgG antibody titre or IgA antibody titre, but there were stronger and significant relations of IgA antibodies with all cause mortality and fatal ischaemic heart disease, which persisted after adjustment for conventional cardiovascular risk factors. The odds ratios associated with detectable IgA antibodies were 1.07 (95% confidence interval 0.75 to 1.53) for all incident ischaemic heart disease, 1. 83 (1.17 to 2.85) for fatal ischaemic heart disease, and 1.50 (1.10 to 2.04) for all cause mortality. CONCLUSION: This is the first prospective demonstration of an association between IgA antibodies to C pneumoniae, a putative marker of chronic infection, and subsequent risk of death from ischaemic heart disease. In contrast to earlier case-control studies, IgG antibodies were not associated with either prevalent or incident ischaemic heart disease.

Antibodies, Bacterial↗
PubMed1999

Relationship between Helicobacter pylori, gastric parietal cell antibodies and heat shock proteins.

BACKGROUND: The relationship between Helicobacter pylori and autoimmune (type A) gastritis is unclear. Infections may trigger autoimmune phenomena but the underlying mechanisms are unknown. AIM: To determine the relationships between H. pylori infection and gastric parietal cell antibodies (PCA), and PCA and heat shock protein (HSP) antibody. METHODS: Fifty-five serum samples positive for PCA, 22 males and 33 females (median age 61 years, range 29-108 years) were compared with 60 control samples negative for PCA, 24 males and 36 females (median age, 48 years, range 11-91 years). H. pylori infection and HSP65K antibodies were determined by enzyme-linked immunosorbent assay. CagA and VacA status were determined by Western blotting. RESULTS: The prevalence of H. pylori was higher in PCA-positives than controls, 29/55 [53%, 95% confidence interval (CI) 39-66%] versus 13/60 (22%, 95% CI 12-34); P= 0.0009. Age was not a confounding factor. Odds ratio for PCA seropositivity if H. pylori-positive was 4.0 (1.79-9.07), P= 0.003. There was an interaction between age and H. pylori, particularly in younger patients. CagA strains were less common in PCA-positives than controls, 10/29 (35%, 95% CI 19-54) versus 9/13 (69%, 39-91), P< 0.05. HSP65K antibodies were elevated in H. pylori infection but to a similar degree for both PCA-positives and controls. CONCLUSION: H. pylori, particularly CagA-negative strains, are associated with autoimmune gastritis and may be implicated in the pathogenesis of autoimmune (type A) gastritis, particularly in younger persons.

Adolescent↗
PubMed1999

Cytomegalovirus seropositivity and incident ischaemic heart disease in the Caerphilly prospective heart disease study.

OBJECTIVE: To assess the role of cytomegalovirus (CMV) infection in primary ischaemic heart disease. METHODS: Plasma specimens collected during 1979-83 from men in Caerphilly, south Wales, were analysed for IgG antibodies to CMV by enzyme linked immunosorbent assay and latex tests. Incident ischaemic heart disease events were ascertained after five and 10 years from death certificates, hospital records, and ECG changes; 195 incident ischaemic heart disease cases were compared with 216 controls of a similar age drawn from the rest of the cohort. RESULTS: 164 cases (84%) and 180 controls (83%) were seropositive for CMV. Optical density, an indicator of CMV antibody titre, was similar for cases and controls. Among controls, seropositivity was not associated with age, socioeconomic status currently or in childhood, smoking, height, body mass index, blood pressure, total cholesterol, fibrinogen, plasma viscosity, or leucocyte count. The unadjusted odds ratio relating CMV seropositivity to incident ischaemic heart disease was 1.06 (95% confidence interval 0.63 to 1.79) and was little changed (1.11, 0.63 to 1.97) after adjustment for age, smoking, body mass index, systolic blood pressure, total cholesterol, and socioeconomic status currently and in childhood. CONCLUSIONS: CMV infection is unlikely to be a strong risk factor for development of myocardial infarction in middle aged men.

Antibodies, Viral↗
PubMed1998

Relation of Helicobacter pylori infection to 13-year mortality and incident ischemic heart disease in the caerphilly prospective heart disease study.

BACKGROUND: Associations have been suggested between Helicobacter pylori seropositivity, cardiovascular risk factors, and ischemic heart disease (IHD). The effect of this common infection on mortality is uncertain. METHODS AND RESULTS: Plasma specimens collected during 1979 to 1983 from 1796 men in Caerphilly, South Wales, were analyzed for IgG antibodies to H pylori. Cause of death and occurrence of incident IHD events were ascertained over an average of 13.7 years from death certificates, hospital records, and ECG changes at 5-yearly follow-up examinations. Seventy percent of men were seropositive. The prevalence of IHD at entry was similar in men with and without H pylori antibodies (odds ratio [OR], 1.10; 95% CI, 0.87 to 1.40). Seropositivity was significantly (P<0.05) associated with poorer socioeconomic status currently and in childhood, shorter stature, and poorer ventilatory function at entry but not with age, smoking, body mass index, blood pressure, total cholesterol, HDL cholesterol, LDL cholesterol, fibrinogen, plasma viscosity, or heat shock protein antibodies. Thirteen-year incidence of IHD was not significantly associated with H pylori (OR, 1.05; 95% CI, 0.80 to 1.39), but there was a stronger relationship with all-cause mortality (OR, 1.46; 95% CI, 1.12 to 1.92) and fatal IHD (OR, 1.54; 95% CI, 1.03 to 2.30). After adjustment for cardiovascular risk factors and both adult and childhood socioeconomic status, ORs were slightly reduced and lost statistical significance (OR=1.32 [95% CI, 0.99 to 1.78] for all-cause mortality and OR=1.52 [95% CI, 0.99 to 2.34] for fatal IHD). CONCLUSIONS: H pylori infection is unlikely to be as strong a risk factor for IHD as some previous studies have suggested, but its relationship to mortality, including fatal IHD, deserves further investigation. The mechanism underlying these associations is unlikely to involve hypertension, circulating lipid profile, fibrinogen, or cross-reacting antibodies to bacterial heat shock proteins.

Helicobacter Infections↗
PubMed1998

Clinical practice--strategies for management of dyspepsia.

If every person, particularly the young with dyspepsia, were initially tested for Helicobacter pylori and treated if positive and re-assured if negative, a substantial proportion of endoscopies could be saved, and it is difficult to conceive how this would add to the expense of managing dyspepsia if most H. pylori positive dyspeptics are going to receive treatment after endoscopy in any event. An algorithm for the management of dyspepsia is proposed.

Adult↗
PubMed1998

Antibiotic use, childhood affluence and irritable bowel syndrome (IBS).

BACKGROUND: Antibiotics cause well defined short-lived disturbances in bowel habit. There is evidence to suggest that antibiotics may play a role in the pathogenesis of IBS. Atopy has been associated with small household size in childhood and could also play a role in IBS. We conducted a survey examining the relation of drug use and other epidemiological correlates of IBS. SETTING: General practice health screening clinic. SUBJECTS AND METHODS: 421 subjects (46% male, mean age 47 years (range 18-80 years) attending a general practice health screening clinic were interviewed by a research nurse and completed a previously validated questionnaire. Symptoms of IBS were said to be present if abdominal pain with 2 or more Manning criteria symptoms occurred more than once per month over the previous 6 months. RESULTS: 48 subjects had symptoms of IBS. The following were strongly related to its presence: antibiotic use [adjusted OR 3.70 (1.80-7.60)], female sex and childhood living density < 1 person per room [OR 3.47 (1.57-7.64)], manual father's occupation [OR 0.35 (0.16-0.76)]. The use of NSAIDS, H2 antagonists or other types of medication was not greater in this group. CONCLUSION: Antibiotic use is associated with IBS. The association with antibiotic use requires testing in prospective studies. Privileged childhood living conditions were also an important risk factor which is consistent with an allergic aetiology for IBS.

Adolescent↗
PubMed1998

Which Helicobacter pylori-positive dyspeptics are likely to respond symptomatically to empirical H. pylori eradication?

OBJECTIVE: To identify which Helicobacter pylori-positive dyspeptic patients have an increased likelihood of having peptic ulcer and may thus be more likely to benefit from empirical H. pylori eradication therapy. METHODS: 622 out of 740 consecutive dyspeptic subjects (median age 45 years, range 14-91, 51% male) attending for rapid access endoscopy were eligible for the study. Demographic data and endoscopic findings were recorded. H. pylori status was determined by urease and histology. RESULTS: In all age groups, peptic ulcers were commoner in males than females [44% (85/195) vs 23% (32/139), P < 0.001] and in smokers than non-smokers [47% (46/97) vs 32% (50/159), P < 0.05]. Males, heavy smokers and those with a family history of peptic ulcer had increased adjusted odds of having a peptic ulcer (2.59, 1.96 and 1.90, respectively). Corresponding odds ratios for those aged under 45 were 2.59, 0.94 and 2.52. In H. pylori-positive dyspepsia, being a male who either smoked heavily or had a family history of peptic ulcer gave a sensitivity and positive predictive value for peptic ulcer of 86 and 45% for all age groups and 85 and 49% for those aged under 45. CONCLUSION: Male H. pylori dyspeptics who smoke >10 cigarettes per day and/or have a family history of peptic ulcer are likely to have peptic ulcer and are thus likely to benefit from empirical eradication therapy.

Adolescent↗