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Biomedical subjects

T C Northfield

Publications and source records attributed to T C Northfield.

At least 55 records · Page 3Linked to original sources
PubMed1995

Chlamydia pneumoniae: risk factors for seropositivity and association with coronary heart disease.

BACKGROUND: Two studies have suggested that seropositivity for Chlamydia pneumoniae (C. pneumoniae) is a risk factor for coronary heart disease (CHD) but the association remains tenuous. Further data is required in other populations to consolidate this observation. AIMS: Initially to determine descriptive risk factors for C. pneumoniae seropositivity in a general population sample and subsequently to examine the relation of seropositivity for this organism to CHD for the first time in a British population. SETTING: A single general practice health screening clinic and a cardiology clinic involving patients predominantly residing in south London and Surrey. SUBJECTS: 210 consecutive caucasian men (62%) and women (38%) aged 18-79 including 67 men aged 45-65. This latter group acting as controls were then also compared with 103 consecutive males aged 45-65 with angiographically confirmed coronary heart disease. METHODS: A questionnaire was administered by a research nurse and serum was analysed for IgG and IgA against C. pneumoniae and other Chlamydiae by a microimmunofluorescence test. Serum was said to be low positive at a specific IgG antibody titre of 16-32, and high positive if 64 or greater. RESULTS: Amongst the general practice health screening clinic population 14 subjects (7%) were excluded due to possible cross-reactivity with other Chlamydia species (predominantly C. trachomatis). Of the remaining 196 subjects, 13 (6%) had high positive C. pneumoniae IgG titres, 68 (35%) had low titres and 125 had no detectable antibody. After adjustment for sex, age, smoking history, social class and family size only one risk factor for high positive titres in this group was identified, which was the number of children currently living in the home (OR 2.29 (1.09-4.80), P = 0.03). No factors were significantly related to low titres. 22/100 (22%) cases with coronary heart disease and 3/64 (4.7%) of controls had high positive IgG titres for C. pneumoniae. Similarly 21% of cases and 9.4% of controls had positive C. pneumoniae specific IgA serology. 45% of cases and 44% of controls had low C. pneumoniae IgG titres. The association of CHD with a C. pneumoniae IgG titre of 64 or above was independent of all risk factors (OR 7.4 (1.7-33.1), P < 0.01). CONCLUSION: Serological evidence of C. pneumoniae infection is common amongst healthy British subjects. Smoking and social class are not important confounding variables in this study. Reinfection from contact with infected children in the home may be important in inducing higher titres in some subjects. These higher titres are more prevalent in subjects with coronary heart disease in the U.K. as reported in Finland and the U.S.A., and provide further evidence that C. pneumoniae may be important in the pathogenesis of this condition in these populations.

Adolescent↗
PubMed1995

Direct assessment of the mechanism for a raised serum bile acid level in chronic liver disease.

BACKGROUND: Impaired hepatic uptake is the major cause of raised serum bile acid levels in liver disease, but confirmation in humans by direct measurement is lacking. The synthetic gamma-labelled bile acid 75Se-homocholic acid taurine (75SeHCAT) provides a tool for the direct measurement of hepatic bile acid handling. OBJECTIVE: To determine the interrelationships among hepatic handling of 75SeHCAT, the kinetics of its disappearance from plasma and serum bile acid levels in patients with chronic liver disease. DESIGN: We studied 12 patients with primary biliary cirrhosis and 14 with cirrhosis arising from other causes. Fasting serum bile acid levels were measured enzymatically. After intravenous administration of 75SeHCAT, we determined plasma disappearance rates (initial K1, late K2) from serial blood samples and hepatic uptake and excretory rates directly from dynamic abdominal gamma-camera scanning. Both scanning and sampling were carried out over a period of 90 min. RESULTS: Serum bile acid concentrations correlated with K1 and with hepatic uptake (Rs = -0.53, P < 0.01; Rs = -0.47, P < 0.02, respectively) but neither with K2 nor with the excretory rate. K1 and uptake were reduced (P < 0.05) in patients with high serum bile acid levels and in those with varices. Serum bile acid levels were higher in patients with varices (P < 0.05), which might suggest that portosystemic shunting occurred. However, this is unlikely because the varices were not independent of liver function. CONCLUSION: Hepatic bile acid uptake and excretion are independent processes. Hepatic uptake is related to initial, whereas hepatic excretion is related to late, plasma disappearance. Impaired hepatic uptake is a major determinant of the rise in serum bile acid levels in chronic liver disease.

Adult↗
PubMed1995

The effects of unsaturated fatty acids on Helicobacter pylori in vitro.

The effects of three unsaturated free fatty acids on Helicobacter pylori growth in vitro was determined. Growth of H. pylori in Brucella broth was inhibited in a dose-dependent manner by arachidonic, linoleic and oleic acids. The degree of inhibition at any one concentration was related to the degree of fatty acid unsaturation. Triolein, a triacylglycerol ester of oleic acid did not inhibit growth. Inhibition of H. pylori growth was associated with disruption of cell membranes. Incubation with 14C linoleic acid and 14C oleic acid showed incorporation of these fatty acids into H. pylori cell mass and phospholipids leading to alteration of the phospholipid composition of the organism. Incorporation was greater with linoleic than oleic acid and this was associated with a greater inhibition of growth. These findings indicate that H. pylori is sensitive to unsaturated free fatty acids through their incorporation into phospholipids and membrane destruction. This may have therapeutic implications.

Arachidonic Acids↗
PubMed1995

Effect of Helicobacter pylori eradication on gastric metaplasia of the duodenum.

Helicobacter pylori associated duodenal ulcers occur in patches of gastric metaplasia. The pathogenesis of gastric metaplasia is unclear, but it has been produced in experimental animals by acute injury and has been shown to be present to a greater extent of H pylori positive subjects. This study aimed to discover if gastric metaplasia regressed with eradication of H pylori or healing of duodenal ulcers, or both. Thirty two duodenal ulcer patients with H pylori infection confirmed by biopsy urease test and by antral histological examination were studied. Patients were treated with triple therapy (deNol 240 mg twice daily, amoxycillin 500 mg three times daily, and metronidazole 400 mg three times daily) for two weeks after the first endoscopy and were subsequently re-endoscoped. Three duodenal bulb biopsy specimens were obtained per patient at each endoscopy. Biopsy sections were stained with haematoxylin and eosin to determine the severity of duodenitis, and with diastase periodic acid-Schiff/alcian blue to assess the extent of gastric metaplasia. Slides were assessed by two histopathologists unaware of treatment status. H pylori was eradicated in 63% of subjects and all ulcers were healed at follow up. The median extent of gastric metaplasia at the start of treatment and 6-18 months (median 10) after treatment was compared in the two groups. Gastric metaplasia declined in eradicators from 16% to 8% (p < 0.05) while in non-eradicators there was no significant change (25% initially and at follow up). A positive relation between extent of gastric metaplasia and duodenal inflammation score was present before treatment (r(s) = 0.74, p < 0.001) and was unchanged after treatment in the non-eradicator group (r(s) = 0.89, p < 0.001). In the eradicator group, however, the inflammation score had significantly declined (p < 0.02) and the close relation with gastric metaplasia was no longer present. These results suggest that H pylori itself is at least in part responsible for producing gastric metaplasia of the duodenum.

Adult↗
PubMed1995

Serology for Helicobacter pylori compared with symptom questionnaires in screening before direct access endoscopy.

This prospective study aimed to compare serology for Helicobacter pylori with two, symptom questionnaires in screening patients before direct access endoscopy. Methods were compared in terms of the number of endoscopies saved and pathology missed in 315 patients referred to a gastroenterology unit by 65 local GPs. The serology used was based on an acid glycine extract of H pylori. One in-house questionnaire was based on the Glasgow dyspepsia (GLADYS) system and the other questionnaire was that reported by Holdstock et al. A cut off point of 6.3 U/ml for H pylori serology was selected for screening patients (97% sensitive and 75% specific). Serology was combined with a history of NSAID usage in determining who should have endoscopy. For the in-house questionnaire, a cut off score of more than 8 out of a possible maximum of 18 was chosen, after prior evaluation in 118 patients referred for direct access endoscopy (the sensitivity for detection of peptic ulcer was 88%, specificity 61%). A cut off score of more than 412 was used for the Holdstock questionnaire. In patients under 45 years, serology detected more peptic ulcers than the in-house questionnaire and the Holdstock questionnaire (27/28 v 24/28, NS and v 20/28, p < 0.05 respectively). The Holdstock questionnaire saved significantly more endoscopies than the other two methods (76/149 v 57/149 for the in-house questionnaire, p = 0.05 and 59/149 for serology, p = 0.05). In all age groups combined, serology was significantly better than the in-house and Holdstock questionnaires at detecting peptic ulcers and gastric cancer (61/63, 52/63, p<0.02, and 50/63, p<0.01 respectively). But serology saved significantly fewer endoscopies (89/315, 135/315, p<0.005, and 119/315, p<0.05 respectively). Serology was inferior to the Holdstock questionnaire at detecting severe oesophagitis. It is concluded that serology is the method of choice in screening before direct access upper gastrointestinal endoscopy in those under 45 years. It best combines a high sensitivity for peptic ulcer disease with a large reduction in unnecessary negative endoscopies.

Adolescent↗
PubMed1995

Expression of trefoil peptides pS2 and human spasmolytic polypeptide in gastric metaplasia at the margin of duodenal ulcers.

Duodenal ulcers are associated with gastric metaplasia in the duodenum, both at the ulcer margin and at more distant sites in the duodenal bulb. pS2 and human spasmolytic polypeptide (hSP) are secretory peptides expressed in gastric epithelial cells and in gastric metaplasia. As these peptides may be important in ulcer healing, this study investigated the possibility that the expression of pS2 and hSP is increased in gastric metaplasia at the margin of duodenal ulcers. Duodenal bulb biopsy specimens from 12 duodenal ulcer patients were assessed. Sections were immunostained with monoclonal antibodies for pS2 and hSP. Cytoplasmic stain intensities were measured by an image analysis system and expressed as integrated optical density (IOD) units, In situ hybridisation for pS2 and hSP mRNA was carried out on parallel sections. Duodenal sections were also stained with diatase periodic acid Schiff/alcian blue to localise areas of gastric metaplasia. pS2 antigen staining in the duodenum was restricted to surface epithelial cells, and hSP to acinar and ductular components of Brunner's gland. mRNA localisation corresponded to immunostaining cells. In gastric metaplasia, pS2 expression was greater at the ulcer margin than away from the ulcer, as judged by the intensity of antibody staining (mean IOD units (SEM), 20.6 (3.3) v 9.5 (3.0); p < 0.001). There was a trend towards greater hSP staining at the ulcer margin but this did not achieve statistical significance. These findings support the putative role of pS2 and possible hSP in mucosal healing and providy further evidence for an autocrine 'ulcer-gastric metaplasia-repair' loop involving these trefoil peptides.

Brunner Glands↗
PubMed1995

Helicobacter pylori infection density and gastric inflammation in duodenal ulcer and non-ulcer subjects.

The factors that determine which Helicobacter pylori infected subjects develop duodenal ulcer (DU) are unclear. This study tested the hypothesis that infection density and urease activity are higher in DU than non-DU subjects. Fifty five DU and 55 age and sex matched non-DU subjects were studied. Quantitative methods were used for measuring infection density (viable organism count) and urease activity (Berthelot reaction). DU subjects had a greater antral infection density (geometric mean of colony forming units/mg biopsy protein; 10.5 x 10(5) v 1.3 x 10(5), p < 0.001). They also had higher biopsy urease activity (geometric mean of NH3 nmol/min-1/mg protein-1; 103 v 25, p < 0.001). Urease activity per organism, however, was similar in the two groups showing that high antral urease activity in DU was a reflection of organism density. DU was not present in subjects with an antral infection density less than 10(5) colony forming units/mg protein. A correlation was present between H pylori viable counts and the severity and activity of gastritis. Both severity and activity of gastritis were greater in the antrum of DU compared with non-DU subjects but there was no difference in the body between the two groups. It is concluded that antral H pylori infection density is probably an important determinant of DU development, and that there is a baseline of infection density that is necessary for ulcer formation.

Adult↗
PubMed1995

Intrahepatic biliary cholesterol and phospholipid transport in humans: effect of obesity and cholesterol cholelithiasis.

The mode of transport of biliary lipids within the hepatocyte and the role of the bile canalicular membrane (BCM) in biliary lipid secretion are not well understood. We hypothesized that biliary cholesterol and phospholipid are co-transported across the hepatocyte in vesicular form from the endoplasmic reticulum to the bile across the BCM. We obtained wedge liver biopsies and fasting gallbladder bile from 15 cholesterol gallstone patients and 10 control subjects. BCM, basolateral membrane (BLM), and many microsomal vesicular fractions were isolated by centrifugation. One of the vesicular fractions (V3) was enriched in both the microsomal and the BCM marker enzymes and had a high phosphatidylcholine proportion in its phospholipid with a fatty acid pattern similar to biliary phosphatidylcholine. Moreover, its cholesterol content was increased in the obese cholesterol gallstone subjects, who had an increase in cholesterol synthesis, as indicated by the increased activity of the HMG-CoA reductase. The cholesterol content correlated with HMG-CoA reductase activity. A direct correlation was found between cholesterol/phospholipid ratio in V3, BCM, and in bile but not in the BLM. These data are in agreement with the assumption that this vesicular fraction is involved in the transport of cholesterol and phospholipid from the endoplasmic reticulum to the site of secretion in the BCM, and thence to bile, and that this transport is enhanced in obese gallstone patients.

Bile Canaliculi↗
PubMed1994

Helicobacter pylori infection in childhood: risk factors and effect on growth.

OBJECTIVE: To investigate the current prevalence of Helicobacter pylori infection in childhood, the risk factors for infection, and the effect of infection on growth in preadolescent schoolchildren. DESIGN: Population based sample of 7 year old schoolchildren followed up at age 11; data on risk factors for infection collected at age 7; presence of infection at age 11 determined by measurement of salivary IgG against H pylori by a newly developed enzyme linked immunosorbent assay (ELISA). Height was measured at 7 and 11 years of age. SUBJECTS: 554 schoolchildren from Edinburgh. RESULTS: 62 (11%) children had H pylori infection. Independent risk factors for infection were single parent families (adjusted odds ratio = 2.5; 95% confidence interval 1.1 to 5.7), the 10% most crowded homes (3.1; 1.3 to 7.2), and schools serving predominantly rented housing estates (2.5; 1.0 to 6.5). School catchment area was more important than parental social class or housing tenure. Growth in height between 7 and 11 was diminished in infected children by a mean of 1.1 cm (0.3 to 2.0 cm) over four years. This growth reduction was largely confined to girls (1.6 cm over four years), among whom it correlated with salivary IgG (P = 0.015). CONCLUSION: Data from salivary assay to investigate the epidemiology of H pylori suggest that factors relating to the type of community in which the child lives may now be as important for acquisition of this infection as features of the family home. The greater reduction of growth among infected girls raises the possibility that H pylori infection may delay or diminish the pubertal growth spurt.

Child↗
PubMed1994

Salivary antibodies to Helicobacter pylori: screening dyspeptic patients before endoscopy.

Diagnostic tests on saliva have advantages compared with those on serum. In 119 consecutive dyspeptic patients referred for endoscopy we developed and validated an enzyme-linked immunosorbent assay to detect salivary immunoglobulins to Helicobacter pylori. Salivary IgG distinguished positive and negative cases (p < 0.0001), but salivary IgA did not. The optimum performance of salivary IgG (85%) was similar to that of serum IgG (90%) and better than that of salivary IgA. Using our assay and a history of regular use of non-steroidal anti-inflammatories in screening patients under 45 years, we detected all peptic ulcers while saving 39% of endoscopies.

Adolescent↗
PubMed1994

Soluble intercellular adhesion molecule-1 in primary biliary cirrhosis: relationship with disease stage, immune activity and cholestasis.

Intercellular adhesion molecule-1, strongly expressed on the interlobular and proliferating bile ducts in primary biliary cirrhosis, is important in the migration and adhesion of inflammatory cells from the circulation to these structures. A soluble form has been found to be elevated in serum in primary biliary cirrhosis. Our aim was to check on the role of soluble intercellular adhesion molecule-1 in primary biliary cirrhosis with particular reference to its specificity by comparison with other disease control groups and to assess its relationship with stage of disease activity, circulating lymphocyte activation and cholestasis. Soluble intercellular adhesion molecule-1 (enzyme-linked immunosorbent assay) and liver biochemistry were measured in 41 patients with primary biliary cirrhosis, 9 with primary sclerosing cholangitis, 12 with alcoholic liver disease and 17 healthy controls. In subgroups of patients with primary biliary cirrhosis, lymphocyte activation and hepatic bile acid uptake and excretory rates were determined. Soluble intercellular adhesion molecule-1 was significantly higher in all three disease groups. Levels in primary biliary cirrhosis and primary sclerosing cholangitis were similar and significantly higher than alcoholic liver disease. Soluble intercellular adhesion molecule-1 expression was greater in late primary biliary cirrhosis than early disease and correlated with histological progression. Correlations were also found with alkaline phosphatase, gamma-glutamyl transpeptidase and conjugated bilirubin. A trend toward an inverse correlation with hepatic excretory rate was found, but no correlation was detected with circulating lymphocyte interleukin-2 receptor expression.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Kinetics of hepatic bile acid handling in cholestatic liver disease: effect of ursodeoxycholic acid.

BACKGROUND/AIMS: Ursodeoxycholic acid (UDCA) is clinically beneficial in chronic cholestatic liver disease, but the underlying mechanisms are unclear. It has been suggested that intrahepatic retention of endogenous hydrophobic bile acids contributes to cholestasis and that the hydrophilic bile acid UDCA reduces this retention; the aim of our study was to test these hypotheses. METHODS: Twelve patients with primary biliary cirrhosis (PBC) and 5 with primary sclerosing cholangitis (PSC) were studied before and during UDCA (10 mg.kg-1.day-1) and compared with 11 healthy controls. Following intravenous 75Se labeled homocholic acid taurine (75SeHCAT) in the fasting state, abdominal gamma camera imaging was performed for 90 minutes. Initial hepatic uptake, transit time, net, and absolute excretory rates for 75SeHCAT were measured. RESULTS: Mean initial hepatic uptake was not different between patients and controls (17.2% and 19.9% dose/minute, not significant). However, net and absolute excretory rates were significantly reduced in patients (1.4% vs. 3.7% dose/minute, P < 0.0001; and 2.35% vs. 3.96% dose/minute, P < 0.02, respectively), and hepatic transit time was prolonged (18.7 minutes vs. 11.6 minutes, P < 0.002). UDCA improved net and absolute hepatic excretory rates and transit time (1.43% to 1.96% dose/minute, P < 0.001; 2.35% to 3.15% dose/minute, P < 0.005 and 18.7 to 14.7 minutes, P < 0.001, respectively). However, UDCA did not alter initial hepatic uptake. CONCLUSIONS: In PBC and PSC, there is a defect in hepatic bile acid excretion but not in uptake, implying bile acid retention. This retention is reduced by UDCA.

Adult↗
PubMed1994

Relation of Helicobacter pylori infection and coronary heart disease.

BACKGROUND: There is evidence suggesting that early life experience may influence adult risk of coronary heart disease (CHD). Chronic bacterial infections have been associated with CHD. OBJECTIVE: To determine whether Helicobacter pylori, a childhood acquired chronic bacterial infection, is associated with an increased risk of coronary heart disease in later life. DESIGN: Case-control study controlling for potential confounding variables with an opportunistically recruited control group. SUBJECTS: 111 consecutive cases with documented CHD were recruited from a cardiology clinic and 74 controls from a general practice health screening clinic. All were white men aged 45-65. METHODS: Serum was analysed for the presence of H pylori specific IgG antibodies by ELISA (98% sensitive and 94% specific for the presence of infection). RESULTS: 59% of the cases and 39% of the controls were seropositive for H pylori (odds ratio 2.28, chi 2 7.35, p = 0.007). After adjustment by multiple logistic regression for age, cardiovascular risk factors, and current social class, the effect of H pylori was little altered (odds ratio 2.15, p = 0.03). Further adjustment for various features of the childhood environment known to be risk factors for H pylori infection only slightly weakened the association (odds ratio 1.9). H pylori seropositivity was not related to the level of risk factors in the control population. CONCLUSION: In this pilot study the association of adult coronary heart disease with H pylori seropositivity suggests that the early childhood environment may be important in determining the risk of CHD in adult life. The association needs confirmation in other better designed studies. If H pylori itself is responsible for the association, then this is of great potential importance as the infection is treatable.

Aged↗
PubMed1994

Pharmacological treatment of gallstones. Practical guidelines.

Laparoscopic cholecystectomy is the treatment of choice for symptomatic cholelithiasis. Medical treatment is indicated for patients who are not fit or are afraid of surgery. For any form of medical treatment to be effective gallstones must be cholesterol rich, thus radiolucent, and the cystic duct must be patent, as indicated by gallbladder opacification on oral cholecystography. Three forms of medical treatment are currently available for clinical use--oral bile acids, bile acids as adjuncts to lithotripsy and contact dissolution using methyltertbutylether. The choice of treatment depends mainly on gallstone size. Gallstones < 6 mm in diameter are best treated with oral bile acids, chenodeoxycholic acid 15 mg/kg/day or ursodeoxycholic acid 10 mg/kg/day given alone or in combination (5 mg/kg/day each). Careful patient selection and bedtime administration of the whole daily bile acid dose enhance treatment, and may achieve up to 75% complete dissolution annually. Single stones < 30 mm in diameter or multiple stones (n < 3) are best treated with lithotripsy combined with oral bile acid for dissolution of fragments. Annual dissolution rates are about 80 and 40% for single and multiple stones, respectively. Stones of any size and number can be dissolved by direct contact dissolution using methyltertbutylether. Dissolution has been reported to be complete in almost 100% of stones, but debris is frequently left behind in the gallbladder. Following dissolution using any form of treatment, gallstones recur in about 50% of patients, and cannot be reliably prevented by low dose bile acid or dietary manipulations. Failing prevention, early detection and retreatment of recurrent stones is the best alternative option as a long term strategy.

Algorithms↗