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Biomedical subjects

Alan B R Thomson

Publications and source records attributed to Alan B R Thomson.

35 records · Page 2Linked to original sources
PubMed2003

Effect of steroids on intestinal lipid uptake in rats is enhanced by a saturated fatty acid diet. Cell and molecular biology collaborative network in gastrointestinal physiology.

Glucocorticosteroids enhance sugar digestive and absorptive functions of the intestine, but their effect on lipid uptake is unknown. Modifications in dietary lipids alter the nutrient transport properties of the intestine. The influence of 4 weeks' treatment with budesonide (BUD), prednisone (PRED), or control vehicle in weanling rats fed either an isocaloric semisynthetic saturated fatty acid diet (SFA) or a polyunsaturated fatty acid diet (PUFA), on the uptake of lipids was assessed using everted gut rings. PRED and BUD increased the uptake of several fatty acids, and this was higher when the animals were fed SFA rather than PUFA. Changes in expression of the mRNAs for L-FABP (liver fatty acid binding protein) and ILBP (ileal lipid binding protein) did not explain these alterations in lipid uptake. Dietary lipid signalling of this adaptive response may involve proglucagon, c-jun, TNF-alpha and IL-10, whereas steroid signalling may involve proglucagon. In summary, steroids increase the absorption of lipids by a process which can be enhanced by the substitution of saturated for polyunsaturated lipids in the diet, and which is not explained by alterations in the expression of the mRNAs of L-FABP or ILBP.

Adaptation, Biological↗
PubMed2003

Acid inhibitory potency of twice a day omeprazole is not affected by eradication of Helicobacter pylori in healthy volunteers.

BACKGROUND AND AIMS: The acid inhibitory effect of proton pump inhibitors is reported to be greater in the presence than in the absence of an H. pylori infection. This study was undertaken to test the hypothesis that the acid inhibitory effect of omeprazole given twice a day is greater in H. pylori infected healthy volunteers than in the same individuals following eradication because of differences in the pharmacodynamics of omeprazole, greater duodenogastric reflux, the effects of ammonia produced by the H. pylori, or lower gastric juice concentrations of selected cytokines, which may inhibit gastric acid secretion. MATERIALS AND METHODS: We undertook 24-hour pH-metry in 12 H. pylori-positive healthy volunteers: (1) when on no omeprazole; (2) when on omeprazole 20 mg bid for 8 days; (3) 2 months after eradication of H. pylori and when on no omeprazole; and (4) after eradication of H. pylori and when on omeprazole 20 mg twice a day. RESULTS: In subjects given omeprazole, eradication of H. pylori reduced pH and percentage pH >or= 3, as well as increasing the area under the H+ concentration-time curve. These differences were not due to alterations in (1) gastric juice concentrations of IL-1alpha, IL-8, IL-13, epidermal growth factor, or bile acids; (2) serum gastrin concentrations; or (3) the pharmacokinetics of omeprazole. There was no change in the difference in the H+ concentration-time curve 'without omeprazole' minus 'with omeprazole', when comparing 'after' versus 'before' eradication of H. pylori. CONCLUSIONS: Eradication of H. pylori was not associated with an alteration in the acid inhibitory potency when comparing the difference in gastric acidity 'with' versus 'without' omeprazole. When the results were expressed by simply taking into account the acid measurements while on omeprazole before versus after eradication of H. pylori, the acid inhibition with omeprazole was greater in the presence than in the absence of a H. pylori infection. The clinical significance of the small difference is not clear.

Adult↗
PubMed2003

The hepatic retinyl ester hydrolase activity is depressed at the onset of diabetes in BB rats.

Dietary vitamin A as retinyl ester is hydrolysed and re-esterified with long-chain fatty acids in the small intestine. The esterified vitamin A is subsequently stored in the liver, where it is hydrolysed to free retinol to be transported by carrier proteins to the target tissue. A decreased availability of retinol carrier proteins has been suggested to be responsible for affecting metabolic availability of vitamin A in type 1 diabetes. Using BB Wistar rats, the present study was undertaken to examine whether the presence of a hyperglycaemic state modifies retinyl ester hydrolase (REH) activity in the intestine and the liver. At the onset of diabetes, hepatic REH enzymatic activity was significantly decreased. However, REH activity remained unaffected in the small intestine, including both ileum and jejunum. Diabetes also resulted in decreased plasma and liver concentrations of retinol. An in vitro study was conducted to examine the effect of diabetes on the intestinal uptake of retinyl palmitate. Jejunum and ileum from diabetic and non-diabetic BB rats were incubated with labelled retinyl palmitate at different concentrations ranging from 32 to 256 nmol/l. The uptake of retinyl palmitate was increased in both diabetic and non-diabetic rats together with the increase of substrate concentration. However, no significant difference was observed in the uptake of retinyl palmitate between diabetic and non-diabetic rats. These present results suggest that the depressed hepatic REH activities may contribute to the diabetes-associated metabolic derangement of vitamin A.

Animals↗
PubMed2002

Nutrient absorption and intestinal adaptation with ageing.

Malabsorption of carbohydrates, lipids, amino acids, minerals and vitamins has been described in the elderly. The ability of the intestine to adapt may be impaired in the elderly and this may lead to further malnutrition. Dietary manipulation may prove to be useful to enhance the needed intestinal absorption with ageing. There is an age-associated increase in the prevalence of dyslipidaemia as well as diabetes. These conditions may benefit from nutritional intervention targeted at reducing the absorption of some nutrients. With the continued characterization of the proteins involved in sterol and fatty acid absorption, therapeutic interventions to modify absorption may become available in the future.

Adaptation, Physiological↗
PubMed2002

Risks and benefits of Helicobacter pylori eradication: current status.

In patients with diseases known to be associated with Helicobacter pylori infection, such as peptic ulcer, treatment of the underlying infection is the standard of care. However, in most major consensus management guidelines, including those published in Canada, widespread testing for H pylori infection is not recommended. This practice is not encouraged because of insufficient evidence of cost-benefit in gastric cancer prevention, the potential for increases in antibiotic resistance and the controversial hypothesis of potential negative effects of eradication in certain clinical entities. For example, there is insufficient evidence to recommend against eradicating H pylori discovered in a patient with symptoms of gastroesophageal reflux disease. The management guidelines designed specifically in Canada should, therefore, continue to be applied, with H pylori diagnosed and treated in appropriately selected patients.

Gastrointestinal Diseases↗
PubMed2002

Recommendations for the appropriate use of anti-inflammatory drugs in the era of the coxibs: defining the role of gastroprotective agents.

Treatment with anti-inflammatory drugs and the analgesic efficacy of conventional nonsteroidal anti-inflammatory drugs (NSAIDs) are compromised by a two- to fourfold increased risk of gastrointestinal complications. This increased risk has resulted in an increasing use of the new selective cyclooxygenase-2 inhibitors or coxibs, which, in clinical trials and outcomes studies, reduced gastrointestinal adverse events by 50% to 65% compared with conventional NSAIDs. However, the coxibs are not available to all patients who need them, and NSAIDs are still widely used. Moreover, treatment with a coxib cannot heal pre-existing gastrointestinal lesions, and cotherapy with an anti-secretory drug or mucosal protective agent may be required. This paper addresses the management of patients with risk factors for gastrointestinal complications who are taking NSAIDs and makes recommendations for the appropriate use of 'gastroprotective' agents (GPAs) in patients who need to take an NSAID or a coxib. When economically possible, a coxib alone is preferable to a conventional NSAID plus a GPA to minimize exposure to potential gastrointestinal damage and avoid unnecessary dual therapy. Patients at high risk require a GPA in addition to a coxib.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2002

Etiology of dyspepsia: implications for empirical therapy.

Dyspepsia describes a symptom complex thought to arise in the upper gastrointestinal tract and includes, in addition to epigastric pain or discomfort, symptoms such as heartburn, acid regurgitation, excessive burping or belching, a feeling of slow digestion, early satiety, nausea and bloating. Based on the evidence that heartburn cannot be reliably distinguished from other dyspeptic symptoms, the Rome definition appears to be too narrow and restrictive. It is particularly ill suited to the management of uninvestigated dyspepsia at the level of primary care. In patients presenting with uninvestigated dyspepsia, a symptom benefit is associated with a 'test and treat' approach for Helicobacter pylori infection. A substantial proportion of those who do not benefit prove to have esophagitis on endoscopy. In those with functional dyspepsia, the benefits of H pylori eradication, if any, appear to be modest. Hence, a 'symptom and treat' acid-suppression trial with proton pump inhibitors, and a 'test and treat' strategy for H pylori are two acceptable empirical therapies for patients with univestigated dyspepsia.

Age Factors↗
PubMed2002

Lack of therapeutic effect of a specially designed yogurt for the eradication of Helicobacter pylori infection.

BACKGROUND: Current antibiotic treatment for Helicobacter pylori infection is often associated with frequent adverse effects and resistance to antibiotics. Alternative treatment methods to control H. pylori infection are needed. Some specific strains of lactic acid bacteria (probiotics) in dairy products are known to inhibit the growth of H. pylori in vitro. A clinical trial was conducted to see the efficacy of a specially designed yogurt product containing specific probiotics on the eradication of H. pylori. METHOD: The yogurt was prepared using three Lactobacillus spp. (L. acidophilus and L. casei) and one commercial starter culture (L. acidophilus, L. bulgaricus and Streptococcus thermophilus). All these cultures were previously evaluated, and found to have strong in vitro inhibitory effects on the growth of H. pylori. Twenty-seven asymptomatic women positive for H. pylori on gastric biopsy and 13C urea breath test were recruited, and administered 175 ml of the yogurt three times a day for 30 days. The 13C urea breath test was administered again, one month after stopping the yogurt treatment to detect the presence of H. pylori. RESULTS: In 26 of 27 subjects, the urea breath test values remained positive, indicating that the consumption of the yogurt had no effect on the eradication of H. pylori. CONCLUSION: Although the designed fermented milk containing lactobacilli is very effective in the inhibition of H. pylori growth in vitro, eradication of this infection in humans is difficult to achieve by consuming this product.

Adult↗
PubMed2002

14 day endoscopy study comparing risedronate and alendronate in postmenopausal women stratified by Helicobacter pylori status.

OBJECTIVE: Bisphosphonates are effective treatment for osteoporosis but have been associated with gastrointestinal (GI) mucosal injury. This study compared the incidence of gastric ulcers after treatment with risedronate, a pyridinyl bisphosphonate, or alendronate, a primary amino bisphosphonate, in healthy postmenopausal women stratified by Helicobacter pylori status. METHODS: Subjects were randomized to receive risedronate 5 mg (n = 318) or alendronate 10 mg (n = 317) daily for 14 days. Endoscopy and evaluator-blind assessments of the esophageal, gastric, and duodenal mucosa were performed at baseline and on Days 8 and 15. RESULTS: Overall, gastric ulcers > or = 3 mm were observed in 18 (6.0%) of 300 evaluable subjects in the risedronate group and 36 (12.1%) of 297 in the alendronate group during treatment (p = 0.013). On Day 8, the incidences of gastric ulcers in the risedronate and alendronate groups were 3.6% and 6.6%, respectively (p = 0.133), and on Day 15, they were 3.3% and 8.7% (p = 0.008). The incidence of gastric ulcers was not affected by H. pylori status. Mean gastric endoscopy scores at Days 8 and 15 were significantly lower in the risedronate group than in the alendronate group (p < 0.001). Mean esophageal and duodenal endoscopy scores were similar in the 2 groups at Days 8 and 15. When the treatment groups were combined, gastric endoscopy scores were significantly higher among H. pylori negative than H. pylori positive subjects at Days 8 and 15 (p < 0.05). Upper GI adverse events were reported by 18 (5.7%) subjects in the risedronate group (19 events) and 28 (8.8%) subjects in the alendronate group (32 events). Symptoms did not predict the presence of mucosal damage. CONCLUSION: Risedronate was associated with a significantly lower incidence of gastric ulcers than alendronate. H. pylori infection did not increase the incidence of bisphosphonate related gastric ulcers. The findings from this 14 day study in healthy volunteers support the hypothesis that bisphosphonates may differ from one another in their potential to produce upper GI mucosal damage.

Aged↗
PubMed2002

Intracellular lipid binding proteins of the small intestine.

The small intestine contains three distinct proteins belonging to the intracellular lipid binding protein family: the liver-type fatty acid binding protein (L-FABP), the intestinal fatty acid binding protein (I-FABP) and the ileal lipid binding protein (ilbp). The function of these proteins in the small intestine has remained enigmatic. Targeted gene disruption studies may shed insights into the physiological importance of these proteins. In the case of I-FABP, this approach has demonstrated that the complete elimination of this protein in murine intestine does not compromise dietary fat absorption in vivo but is associated with the development of insulin resistance.

Animals↗
PubMedDate not supplied

Short-chain fatty acids and total parenteral nutrition affect intestinal gene expression.

BACKGROUND: The supplementation of total parenteral nutrition (TPN) formulas with short-chain fatty acids (SCFAs) increases glucose uptake and the expression of glucose transporters in parenterally fed animals. Several signals may be involved in intestinal adaptation; however, increased messenger RNA (mRNA) levels for proglucagon and several early-response genes, including c-myc and c-fos, are seen in animals receiving SCFA-supplemented TPN. Although the effects of a mixture of SCFAs are well documented, the relative contribution of individual SCFAs is unknown. Butyrate is a preferred fuel of colonocytes, with documented effects on cellular proliferation and gene expression. Accordingly, this study was undertaken to determine the relative role of butyrate in initiating an adaptive response in nonresected rats receiving TPN. METHODS: Animals received standard TPN for 66 hours, followed by 6 hours of either standard TPN, TPN supplemented with a mixture of SCFAs (acetate, propionate, and butyrate, 60 mmol/L total), or TPN supplemented with butyrate alone (9 mmol/L). An oral control group was fed an elemental diet, similar in macronutrient content to the TPN, so that all animals received the same amount of energy daily. RESULTS: SCFAs increased ileal glucose transporter 2 (GLUT2) mRNA expression compared with the orally fed group. SCFAs also increased proglucagon mRNA expression compared with the TPN group. No changes in Na+K(+)-adenosine triphosphatase or early-response gene expression were found in this study. CONCLUSIONS: In a rat model of TPN, the use of 9 mmol/L butyrate did not have the same effect on GLUT2 and proglucagon expression as a 60-mmol/L mixture of SCFAs. This suggests that the effect of a mixture of SCFAs on intestinal gene expression is not butyrate specific.

Animals↗
PubMedDate not supplied

Dexamethasone plus glucagon-like peptide 2 given to lactating rat dams has a late effect on intestinal lipid uptake in the weanling offspring.

BACKGROUND: Glucagon-like peptide 2 (GLP-2) has a trophic effect on the intestine and enhances intestinal absorption in adult animals, but its effect in young rats is unknown. Glucocorticosteroids accelerate the ontogeny of the intestine, and in adult animals they increase the uptake of sugars and lipids. We hypothesized that GLP-2 and dexamethasone (DEX), when administrated to lactating rat dams, will enhance lipid uptake in the suckling and weanling offspring. METHODS: Eight nursing rats were treated during lactation, 19 to 21 days, with GLP-2 (0.1 microg/g/d subcutaneously [s.c.]), DEX (0.128 microg/g/d s.c.), GLP-2 + DEX (GLP-2 0.1 microg/g/d s.c. plus DEX 0.128 microg/g/d s.c.), or placebo. Half of the offspring ("sucklings") were killed at 19 to 21 days of age, and half were killed 4 weeks later ("weanlings"). The rate of intestinal uptake of fatty acids (12:0, lauric; 16:0, palmitic; 18:0, stearic; 18:1, oleic; 18:2, linoleic; and 18:3, linolenic) and cholesterol were assessed using an in vitro ring technique. RESULTS: GLP-2 and DEX resulted in loss of body weight in sucklings, which was prevented by giving the combination GLP-2 + DEX. The jejunal atrophy in sucklings given DEX was prevented by giving GLP-2 + DEX, but GLP-2 + DEX did not prevent the decline in jejunal and ileal villous height and crypt depth observed in weanlings given DEX. GLP-2 had little effect on lipid uptake in sucklings, whereas DEX or GLP-2 + DEX increased the uptake of lipids. In contrast, in weanlings there was malabsorption of several lipids with GLP-2 or GLP-2 + DEX, but not with DEX. Lipid uptake was lower in weanlings than in sucklings, and this age-associated decline was not altered by GLP-2 or DEX. CONCLUSIONS: The loss of body weight and the jejunal atrophy induced by DEX in sucklings is prevented by adding GLP-2. Giving DEX or GLP-2 + DEX to lactating mothers enhances lipid uptake in their suckling offspring. In marked contrast, a month after lactating dams were given GLP-2 or GLP-2 + DEX, there was reduced lipid absorption in the postweaning animals. Thus, giving GLP-2 + DEX during lactation may be useful to enhance lipid uptake in the suckling offspring, without adverse effects on body weight or intestinal characteristics. However, the late effects of this treatment on lipid absorption were of concern, and could be potentially deleterious to the nutritional well-being of the animal.

Animals↗