Heterogeneity after harmonisation: A retrospective cohort study of bleeding and stroke risk after the introduction of direct oral anticoagulants in four Western European countries

PURPOSE

Database heterogeneity can impact effect estimates. Harmonisation provided by common protocols and common data models (CDMs) can increase the validity of pharmacoepidemiologic research. In a case study measuring the changes in the safety and effectiveness of stroke prevention therapy after the introduction of direct oral anticoagulants (DOACs), we performed an international comparison.

METHODS

Using data from Stockholm, Denmark, Scotland and Norway, harmonised with a common protocol and CDM, two calendar-based cohorts were created: 2012 and 2017. Patients with a diagnosis code of atrial fibrillation 5 years preceding the 1-year cohort window were included. DOAC, vitamin K antagonist and aspirin treatment were assessed in the 6 months prior to the start of each year while strokes and bleeds were assessed during the year. A Poisson regression generated incidence rate ratios (IRRs) to compare outcomes from 2017 to 2012 adjusted for changes in individual-level baseline characteristics.

RESULTS

In 280 359 patients in the 2012 cohort and 356 779 in the 2017 cohort, treatment with OACs increased on average from 45% to 65%, while treatment with aspirin decreased from 30% to 10%. In all countries except Scotland, there were decreases in the risk of stroke and no changes in bleeding risk, after adjustment for changes in baseline characteristics. In Scotland, major bleeding (IRR 1.09, 95% confidence interval [CI] [1.00; 1.18]) and intracranial haemorrhage (IRR 1.31, 95% CI [1.13; 1.52]) increased from 2012 to 2017.

CONCLUSIONS

Stroke prevention therapy improved from 2012 to 2017 with a corresponding reduction in stroke risk without increasing the risk of bleeding in all countries, except Scotland. The heterogeneity that remains after methodological harmonisation can be informative of the underlying population and database.

Genome-wide association study of patients with atrioventricular nodal reentry tachycardia

Background

Supraventricular tachycardias (SVTs) originate from the atria or the area close to the AV node. AV nodal reentry tachycardia (AVNRT) is one of the tachyarrhytmias comprising the group of SVTs. The typical patient is female, young at disease onset, with a structurally normal heart. At present we do not know the etiology of AVNRT. We therefore hypothesized that AVNRT might be caused by changes in the DNA.

Methods

DNA from purified blood was obtained from patients with AVNRT verified by an invasive electrophysiological study. Patients were recruited from five ablation centers in Denmark and individuals from the general population of Denmark (the BEFUS cohort) served as controls. DNA was subjected to chip genotyping, imputation and analyses in a genome-wide association study (GWAS) setup.

Results

A GWAS on 1,143 AVNRT patients and 3,004 controls revealed one locus close to the gene MYH6 to reach genome-wide significance for association with AVNRT (P=4.8x10–8). MYH6 encodes the α-isoform of the protein myosin heavy chain important for the contractile units of the heart, the sarcomeres. The gene is predominantly expressed in the atria. Additional subthreshold loci located close to other plausible arrhythmia genes were identified.

Conclusion

We report the first genetic locus to be associated with AVNRT close to the sarcomere gene MYH6. This is, to our knowledge, the first gene ever associated with AVNRT.

Manhattan plot

Funding Acknowledgement

Type of funding source: Public hospital(s). Main funding source(s): Rigshospitalets Forskningspulje - 3 years PhD salary

Rare variants in HCN4 identified in the general population are associated with complete atrioventricular (AV) block, 1. degree AV block and bundle branch block, results from 50.000 exomes

Background/Introduction

Cardiac conduction disorders cover disorders such as atrioventricular (AV) block and bundle branch block. Genome-wide association studies have identified more than 100 genetic loci for atrial fibrillation, including HCN4 loci associated with duration of the PR interval, a proxy for AV dysfunction. Recent candidate studies suggest an association between HCN4 variants and AV-block.

Purpose

We seek to determine the contribution of rare genetic variants in HCN4 to complete AV-block, 1. degree AV-block and bundle branch block (BBB) in the general population.

Methods

The UK Biobank is a population-based study of 500 000 individuals including a subset with genome-wide genotyping and exome sequencing (n=45,596). In this case-control study, we included persons of genetically determined white-European ancestry and analyzed their exome data. Analyses were performed using a logistic mixed-effects model. A gene-based burden analysis and single variant test were performed to examine the relationship between HCN4 variants and complete AV-block, 1. degree AV-block and BBB in the general population.

Results

The study included 43,371 persons. In an analysis of the HCN4 genes a significant association between rare variants (MAF<0.01) in HCN4 gene was found (complete AV-block, P=2.5x10–5, 1. degree AV-block, P=1.3x10–3 and BBB, P=0.01) (Figure 1A). The association to complete AV block was mostly driven by the variants Ser835Phe (P=2.7e-3), Glu153Gly (P=3.5e-3) and Arg378Cys (P=6.3e-3) (Figure 1B).

Conclusions

Rare HCN4 variants contribute to the risk of complete AV-block, 1. degree AV-block and BBB in the general population. These HCN4 variants seem to confer a substantial penetrance. Clinical screening for some of these variants seems appropriate.

Figure 1

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): Hallas Møller - Novo nordisk

Rare coding variants in MYH6 are associated with atrial fibrillation: results from 45,596 exomes representing the general population

Background

Atrial Fibrillation (AF) is the most common cardiac arrhythmia, and it is associated with serious complications; including an increased risk of stroke, heart failure, and death. It affects around 5% of the population above 65 years of age, and it is estimated that 2% of healthcare expenses are related to AF. The causes of AF are complex, and includes structural heart disease, hypertension, diabetes and genetic risk factors. To date 166 unique genetic loci have been identified to be associated with AF. While AF has traditionally been regarded as an electrical disease, structural genes, including the sarcomere gene, titin (TTN), has been associated with the disease. Recently, a large genome wide association study associated common variants in the gene MYH6 with AF. The gene encodes the protein alpha myosin heavy chain, and has previously been associated with sick-sinus syndrome and structural heart disease.

Purpose

We hypothesized that genetic variants in the sarcomere gene MYH6 were more prevalent in AF patients than non-AF patients supporting that this gene is important for the development of AF.

Methods

We analysed publicly available data from the UK Biobank, combining exome-sequencing data and health-related information on 45,596 participants. Using next-generation sequencing, we then examined the genetic variation in MYH6 in a cohort of 383 Danish, early-onset AF patients. The patients had onset of AF before age 40, had normal echocardiogram, and no other cardiovascular disease at onset of AF. Genetic variants were filtered by minor allele frequency (MAF) in the Genome Aggregation Database (GnomAD), and only rare variants with MAF<1% were included. We then predicted the potential deleteriousness of the variants using combined annotation dependent depletion (CADD) score.

Results

We found rare coding variants in MYH6 to be significantly associated with AF in exome-sequencing data on 45,596 participants from the UK Biobank (p=0.038).

In our cohort of 383 Danish, early-onset AF patients with no other cardiovascular disease, we identified 12 rare, missense variants in MYH6. Of these variants, three were novel, and 11 had CADD scores >20, suggesting them to be in the top 1% of likely deleterious variants.

Conclusion

We identified rare genetic variants in MYH6 to be significantly associated with AF in a large population-based cohort. We also identified 12 rare coding variants in a highly selected cohort of early-onset AF patients. Most of these variants were predicted to be deleterious.

Our results indicate that rare variants in MYH6 may increase susceptibility to AF, thus elaborating on the understanding of the pathophysiological mechanisms of AF, and the role of structural genes in the development of AF.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): Novo Nordisk Foundation Pre-Graduate Scholarships

Left atrial late gadolinium enhancement is associated with atrial fibrillation as detected by continuous monitoring

Background

Left atrial late gadolinium enhancement (LA LGE) measured with cardiac magnetic resonance (CMR) imaging is emerging as a marker of atrial fibrosis and has been associated with worse outcomes in AF ablation procedures. However, the prognostic value of LA LGE for incident AF remains unknown.

Methods

CMR including measurement of left ventricular (LV) and LA volumes and function, as well as LV extracellular volume fraction and LA LGE, was acquired in 68 patients aged at least 70 years with risk factors for stroke. All included patients received and implantable loop recorder and were continuously monitored for previously unknown AF. Incident AF was adjudicated by senior cardiologists.

Results

Patients were monitored for AF with implantable loop recorder during a median of 41 [36; 43] months. AF episodes lasting ≥6 minutes were detected in 32 patients (47%) and 16 patients (24%) experienced AF episodes lasting ≥5.5-hour. In Cox regression analyses adjusted for sex, age and comorbidities, we found that LA volumes and function and LA LGE were independently associated with incident AF. For LA LGE, the hazard ratio for time to AF episodes lasting ≥6 minutes and ≥5.5 hours were 1.40 (1.03, 1.89) per 10 cm2 increase (p=0.03) and 1.63 (1.11, 2.40) per 10 cm2 increase (p=0.01), respectively. LA LGE was significantly associated with high burden of AF. The addition of LA LGE to a multivariable risk prediction model for incident AF significantly increased the predictive value.

Conclusions

Extent of LA fibrosis measured by LA LGE was significantly associated with incident AF detected by implantable loop recorder.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): The Innovation Fund Denmark, The Research Foundation for the Capital Region of Denmark [no grant number]

Association between maternal diabetes and cardiac left ventricular structure and function in the neonate: a study from the Copenhagen Baby Heart Study

Background

Prenatal exposure to maternal diabetes has been associated with increased risk of congenital heart defects.

Purpose

To evaluate whether maternal diabetes is associated with more subtle morphological and functional cardiac changes in neonates without congenital heart defects.

Methods

We included 17,869 newborns sampled from the Copenhagen Baby Heart Study, all of whom underwent transthoracic echocardiography within 30 days of delivery. We investigated the association between exposure to maternal diabetes (pre-existing diabetes [type 1 or type 2 diabetes] or gestational diabetes [GDM]) and the neonates' echocardiographic indices of left ventricular structure (left posterior wall thickness in end-diastole [LVPWd], interventricular septum thickness in end-diastole [IVSd], left ventricular internal diameter in end-systole [LVIDs] and end-diastole [LVIDd]), systolic function (fractional shortening [FS], stroke volume [SV]) and diastolic function (mitral valve peak early and atrial filling velocities, deceleration time of early filling, and E/A-ratio), using linear and logistic regression. Models were adjusted for maternal age, infant sex, infant birth weight for gestational age and gestational age in days. In additional analyses, we evaluated the relationship between HbA1C levels in first and third trimester and left ventricular structure and function.

Results

We found that infants exposed to pre-existing maternal diabetes (n=x) had, on average, a thicker LVPWd (mean difference 0.12 mm [95% CI: 0.06–0.19]), a smaller LVIDs (−0.27 mm [95% CI: −0.46, −0.07]) and LVIDd (−0.43 mm [95% CI: −0.66, −0.19]), and decreased SV (−0.50 ml [95% CI: −0.77, −0.23]). We found no significant differences in IVSd, FS, and measures of diastolic function for infants exposed to pre-existing maternal diabetes compared with infants not exposed to diabetes. Infants exposed to GDM (n=) also had thicker LVPWd (0.06 mm [95% CI: −0.28, −0.01]) and smaller LVIDs (−0.15 mm [95% CI: −0.28, −0.01]); however, on average, IVSd, LVIDd, and measures of systolic and diastolic function did not differ for infants born to mothers with and without GDM. We observed no consistent association between HbA1C levels measured early and late in pregnancy in mothers with diabetes and indices of left ventricular structure and function.

Conclusion

In conclusion, we found that exposure to maternal pre-existing diabetes, and to a lesser degree GDM, was associated with changes in neonatal left ventricular structure and function, including a thicker left ventricular posterior wall, smaller left ventricular internal diameters, and lower stroke volumes.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): Rigsbospitalet Research Foundation

Genome-wide association study based on cardiac magnetic resonance imaging in 23,634 individuals identifies five new loci associated with left atrial enlargement

 

Left atrial enlargement is associated with mortality due to cardiovascular disease and all-cause mortality. The pathology behind and the association with cardiovascular outcomes are, however, poorly characterised. Compromised atrial function seems to predispose for stroke.

We obtained data from the UK Biobank cardiovascular magnetic resonance (CMR) protocol containing CMR scans from ∼31,000 individuals at the time of study (Fig. 1a). Genome-wide association studies were carried out on state-of-the-art imaging variables exposed to machine learning algorithms to investigate the genetic basis of left atrial volume and function. Deep learning algorithms segmented the atria in the CMR scans (Fig. 1b). Left atrial (LA) volume curves could then be extracted and analysed (Fig. 1c).

We tested 10.6 million variants for association with LA minimum/maximum volumes and LA emptying fraction (LAEF) in 23,624 European individuals without prevalent myocardial infarction or heart failure. We identified five genetic loci located in close proximity to the genes EIF2D, C9orf3, ANKRD1, FGFR2, and MYO18B. We observed a notable genetic correlation between both maximum and minimum LA volumes and stroke and cardioembolic stroke (Fig. 1d).

Conclusions

We report on five genetic loci and suggest several plausible candidate genes important for atrial structural pathology. Genetic correlation analyses indicate that the genetic determinants of LA volumes could be markers of stroke risk. These findings enhance our understanding of the importance of the LA and are potential novel therapeutic targets for cardiovascular disease, including stroke.

Figure 1. LA imaging GWAS

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): Novo Nordisk, Halles Moeller

Hydrochlorothiazide use is strongly associated with risk of lip cancer

BACKGROUND

The diuretic hydrochlorothiazide is amongst the most frequently prescribed drugs in the United States and Western Europe, but there is suggestive evidence that hydrochlorothiazide use increases the risk of lip cancer.

OBJECTIVES

To study the association between use of hydrochlorothiazide and squamous cell carcinoma of the lip.

METHODS

We conducted a case-control study using Danish nationwide registry data. From the Cancer Registry (2004-2012), we identified 633 case patients with squamous cell carcinoma (SCC) of the lip and matched them to 63 067 population controls using a risk-set sampling strategy. Hydrochlorothiazide use (1995-2012) was obtained from the Prescription Registry and defined according to cumulative use. Applying conditional logistic regression, we calculated odds ratios (ORs) for SCC lip cancer associated with hydrochlorothiazide use, adjusting for predefined potential confounders obtained from demographic, prescription and patient registries.

RESULTS

Ever-use of hydrochlorothiazide was associated with an adjusted OR for SCC lip cancer of 2.1 (95% confidence interval (CI): 1.7-2.6), increasing to 3.9 (95%CI: 3.0-4.9) for high use (≥25 000 mg). There was a clear dose-response effect (P < 0.001), with the highest cumulative dose category of hydrochlorothiazide (≥100 000 mg) presenting an OR of 7.7 (95%CI: 5.7-10.5). No association with lip cancer was seen with use of other diuretics or nondiuretic antihypertensives. Assuming causality, we estimated that 11% of the SCC lip cancer cases could be attributed to hydrochlorothiazide use.

CONCLUSIONS

Hydrochlorothiazide use is strongly associated with an increased risk of lip cancer.

Efficacy of partially hydrolyzed guar gum-added oral rehydration solution in the treatment of severe cholera in adults

BACKGROUND

Partially hydrolyzed guar gum (PHGG) is a water-soluble fiber if added to oral rehydration solution (ORS) and undergoes fermentation in the colon liberating short chain fatty acids (SCFAs). SCFAs potentiate the effect of ORS, reducing the severity of diarrhea.

AIM

To examine the effect of PHGG-added ORS in reducing the stool output and duration of diarrhea in adult cholera.

METHODS

195 male patients were studied in a randomized controlled trial: (a) 65 received ORS + 25 g PHGG; (b) 65 received ORS + 50 g PHGG, and (c) 65 received ORS alone (control). Major outcomes were stool weight and duration of diarrhea.

RESULTS

No significant differences were found in mean +/- SD stool weight (g/kg b.w.) during the first and second 24 h. In the subgroup analysis (excluding very high purging patients, stool weight in the first 24 h was >10 kg), the stool weight (g/kg b.w.) was significantly reduced in the first 24 h in both groups receiving PHGG (PHGG 25 g, 136 +/- 68 vs. PHGG 50 g, 144 +/- 49 vs. control, 176 +/- 43, p = 0.01).

CONCLUSION

PHGG-added ORS might have a beneficial effect in moderately purging adult cholera. However, further studies are warranted to confirm the preliminary findings.

Regulation of activity-regulated cytoskeleton protein (Arc) mRNA after acute and chronic electroconvulsive stimulation in the rat

The temporal profile of Arc gene expression after acute and chronic electroconvulsive stimulations (ECS) was studied using semi-quantitative in situ hybridisation in the rat cortex. A single ECS strongly and temporarily increased Arc mRNA levels in dentate granular cells with maximal induction seen up to 4 h after the stimulus, but returned to baseline at 24 h. A single ECS also increased expression of Arc mRNA in the CA1 and the parietal cortex, but the expression peaked within 1 h and returned to baseline levels within 2 h. Repeated or chronic ECS is a model of electroconvulsive therapy and it would be predicted that gene products involved in antidepressant effects accumulate after repeated ECS. However, repeated ECS reduced Arc gene expression in the CA1 24 h after the last stimulus. These results indicate that Arc is an immediate early gene product regulated by an acute excitatory stimulus, but not accumulated by long term repetitive ECS and therefore not a molecular biomarker for antidepressant properties. More likely, Arc is likely a molecular link to the decline in memory consolidation seen in depressive patients subjected to electroconvulsive therapy.

Lymphocytic colitis: a retrospective clinical study of 199 Swedish patients

BACKGROUND

Lymphocytic colitis is characterised by chronic diarrhoea and specific microscopic changes in a macroscopically normal colonic mucosa. We report clinical features and treatment outcome in a large patient cohort.

METHODS

Patients were searched for in 24 Swedish gastroenterology clinics. The biopsy material was reassessed using strict histopathological criteria. Clinical data were obtained from medical notes.

RESULTS

Lymphocytic colitis was diagnosed in 199 cases. The female:male ratio was 2.4:1. Median age at diagnosis was 59 (48-70) years. The most frequent symptoms were diarrhoea (96%), abdominal pain (47%), and weight loss (41%). The course was chronic intermittent in 30% of patients, chronic continuous in 7%, and a single attack in 63%, and in these cases the disease duration was 6 (4-11) months. Seventy nine (40%) patients reported associated diseases, of which thyroid disorders, coeliac disease, and diabetes mellitus were the most common. In 34 first or second degree relatives of 24 (12%) patients, a family history of ulcerative colitis, Crohn's disease, collagenous colitis, or coeliac disease was reported. Drug induced disease was suspected in 19 (10%) patients. A non-significant peak of disease onset was seen in December-January. More than 80% of treated patients improved on corticosteroids, including budesonide.

CONCLUSIONS

A family history of other bowel disorders is a new finding. The sudden onset and single attack of limited duration may support a possible infectious cause in some cases. Drugs may cause lymphocytic colitis.

Microscopic colitis: a common diarrhoeal disease. An epidemiological study in Orebro, Sweden, 1993-1998

BACKGROUND

Microscopic colitis, including collagenous colitis and lymphocytic colitis, mainly affects middle aged and older subjects, with a female predominance in collagenous colitis. The diseases have previously been regarded as rare. We present an epidemiological study of microscopic colitis in a well defined Swedish population.

METHODS

Patients were retrospectively searched for in colonoscopy reports of those who had a colonoscopy in the period 1993-1998 for non-bloody diarrhoea. All colonic mucosal biopsies were reassessed using strict diagnostic criteria.

RESULTS

Biopsies from 1018 patients were reassessed. Fifty one (45 female) collagenous colitis patients and 46 (31 female) lymphocytic colitis patients were diagnosed. Median age at diagnosis was 64 years in collagenous colitis and 59 years in lymphocytic colitis. The mean annual incidence of collagenous colitis was 4.9/10(5) inhabitants (95% confidence interval (CI) 3.6-6.2/10(5)) and of lymphocytic colitis 4.4/10(5) inhabitants (95% CI 3.1-5.7/10(5)). The annual incidence of collagenous colitis increased from 3.7/10(5) in 1993-1995 to 6.1/10(5) in 1996-1998 (difference 2.4/10(5) (95% CI -0.3-5.1/10(5))) whereas the incidence of lymphocytic colitis increased from 3.1/10(5) to 5.7/10(5) (difference 2.6/10(5) (95% CI 0.1-5.2/10(5))).

CONCLUSIONS

The annual incidences of collagenous colitis and lymphocytic colitis are higher than considered previously and are now equal to the incidence of Crohn's disease in Sweden, and combined rates approach the incidence of ulcerative colitis. Microscopic colitis was diagnosed in 10% of all patients with non-bloody diarrhoea referred for colonoscopy and in almost 20% of those older than 70 years.

Luminal nitric oxide and epithelial expression of inducible and endothelial nitric oxide synthase in collagenous and lymphocytic colitis

BACKGROUND

Colonic nitric oxide (NO) production in collagenous colitis (CC) has been studied in a small number of patients and found increased. The cellular source of NO is believed to be the colonic epithelial cells. The aim of this study was to investigate colonic NO levels in patients with CC and lymphocytic colitis (LC), to compare with the histopathological status and with the clinical activity, and to assess the epithelial expression of inducible and endothelial nitric oxide synthase (iNOS and eNOS).

METHODS

We included 19 patients with CC, 8 patients with LC and 15 controls. During colonoscopy, luminal gas was sampled and NO levels were measured using the chemiluminescence technique. Mucosal biopsies were obtained for routine histopathologic examination and immunohistochemical studies of iNOS and eNOS. Clinical activity, as measured by the mean frequency of daily bowel movements during the week prior to colonoscopy, was assessed.

RESULTS

Luminal NO levels, median (25-75 percentiles), in the patients with CC and LC were greatly increased compared to the controls, 1673 (145-8143) parts per billion (ppb) and 1838 (1065-2694) ppb versus 28 (20-46) ppb (P < 0.005, both). A positive association was seen between NO levels and histopathological status as well as clinical activity. Strong expression of iNOS was seen in the surface epithelium in 5 of 6 patients with CC and in 2 of 5 patients with LC.

CONCLUSIONS

The fact that luminal NO levels are related to histopathological status and correlate with clinical activity indicates that NO is involved in the pathophysiology of CC and LC. The epithelial cells are the most likely source of luminal NO.

Familial occurrence of microscopic colitis: a report on five families

BACKGROUND

The etiology and pathogenesis of microscopic colitis is unknown. Whether genetic predisposition is of importance, as in many other gastrointestinal diseases, is unknown. Familial occurrence of collagenous colitis has earlier been reported only in two families.

METHODS

Familial occurrence of microscopic colitis was searched for in a Swedish national microscopic colitis register.

RESULTS

Familial occurrence of microscopic colitis was identified in five families. In all families a sister-sister relationship was found. Two sisters with collagenous colitis had been living apart in different Nordic countries for many years before developing the disease. In one pair, the smoking sister had collagenous colitis and the never smoking sister had lymphocytic colitis.

CONCLUSIONS

Considering the relative rarity of microscopic colitis, these findings indicate that a genetic predisposition may be of importance.

Dipeptidyl peptidase IV inhibition reduces the degradation and clearance of GIP and potentiates its insulinotropic and antihyperglycemic effects in anesthetized pigs

Glucose-dependent insulinotropic peptide (GIP) is known to be degraded by dipeptidyl peptidase IV (DPP IV), forming an inactive metabolite, but the extent of the enzyme's role in regulating the biological activity of GIP in vivo is still largely unknown. In nonfasted anesthetized pigs given an intravenous infusion of GIP, the intact peptide (determined by a novel NH(2)-terminally directed radioimmunoassay) accounts for only 14.5 +/- 2.5% of total immunoreactivity. This is increased (to 40.9 +/- 0.9%, P < 0.0001) by coadministration of valine-pyrrolidide (a specific DPP IV inhibitor) at a dose that completely inhibits plasma DPP IV activity. The plasma t(1/2) of intact GIP is prolonged by the inhibitor (from 3.3 +/- 0.3 to 8.1 +/- 0.6 min; P < 0.001), whereas the t(1/2) for COOH-terminal immunoreactivity is unaffected (13.2 +/- 0.5 and 11.5 +/- 0.8 min, pre- and postinhibitor). Measurement of arteriovenous concentration differences revealed that the liver, kidney, and extremities are the main sites of removal of exogenous intact GIP (organ extractions, 28.0 +/- 2.2, 26.3 +/- 5.7, and 21.8 +/- 3.0%, respectively). These organ extractions are reduced (P < 0.02) but not eliminated (kidney and extremities) by valine-pyrrolidide (to 6.5 +/- 4.6, 14.1 +/- 3.1, and 13.9 +/- 2.4%, respectively). Valine-pyrrolidide potentiates the insulinotropic effect of GIP (P < 0.02), resulting in an enhanced glucose disappearance rate (k, from 8.0 +/- 0.5 to 15.5 +/- 2.2%/min; P < 0.01) and a reduction in the glucose excursion after an intravenous glucose load (area under the curve, from 133 +/- 23 to 75 +/- 9 min. mmol/l; P < 0.05). These results suggest that DPP IV plays an important role in GIP metabolism but is not the sole enzyme responsible for its NH(2)-terminal degradation. Nevertheless, DPP IV inhibition increases the proportion of intact peptide sufficiently to enhance its insulinotropic and antihyperglycemic effects.

Collagenous and lymphocytic colitis: a clinical and histopathological review

Collagenous colitis and lymphocytic colitis are newly described colitides that are only diagnosable microscopically; therefore, both are known under the umbrella term 'microscopic colitis'. This is a short review of the clinical findings, and epidemiological and basic observations of these relatively little described colitides belonging to the group of inflammatory bowel diseases.

Efficacy, safety, and tolerability of fructooligosaccharides in the treatment of irritable bowel syndrome

BACKGROUND

Interest in fructooligosaccharides as a health-promoting food component is increasing. Fructooligosaccharides are mainly indigestible and large amounts in the colon may provoke gastrointestinal symptoms.

OBJECTIVE

The symptoms of irritable bowel syndrome (IBS) may be provoked by large quantities of carbohydrates in the colon. The objective of this study was to determine whether regular consumption of fructooligosaccharides worsens gastrointestinal symptoms in patients with IBS.

DESIGN

A multicenter, prospective, randomized, double-blind, placebo-controlled parallel group comparison was conducted at 24 sites. The study consisted of a 2-wk, single-blind run-in phase and a 12-wk, double-blind comparative phase. Subjects were randomly assigned to receive 20 g fructooligosaccharides powder/d (n = 52) or a placebo (n = 46). Efficacy was based on the patients' overall response to treatment at completion of the study and on the severity and duration of individual symptoms (abdominal distension, abdominal rumbling, abnormal flatulence, and abdominal pain).

RESULTS

Data from 96 patients (16 men and 80 women) were analyzed. After 4-6 wk of treatment, IBS symptoms improved more in the placebo group than in the fructooligosaccharide group. After completion of the study, there were no significant differences between the 2 groups: symptoms improved in 58% of the fructooligosaccharide group and in 65% of the placebo group and symptoms worsened in 8% of the fructooligosaccharide group and in 13% of the placebo group.

CONCLUSION

Although symptoms worsened in patients with IBS at the onset of treatment with 20 g fructooligosaccharides/d, continuous treatment for 12 wk resulted in no worsening of symptoms.

Importance of colonic bacterial fermentation in short bowel patients: small intestinal malabsorption of easily digestible carbohydrate

The small intestine's large capacity for glucose absorption and for adaptation seems to contradict the reported importance of carbohydrate malabsorption in short bowel (SB) patients. The aim of the present study was to investigate the occurrence of malabsorption in these patients ingesting realistic amounts of carbohydrates. We performed a dose-response study [ingestion of increasing amounts of glucose and complex carbohydrates (boiled rice and wheat bread), and the nonabsorbable disaccharide lactulose] in SB patients with an intact colon. The hydrogen (H2) -breath test and changes in serum acetate were used to evaluate colonic fermentation and, thus, indirectly, the lack of small intestinal carbohydrate assimilation. Blood glucose and plasma insulin were measured to evaluate absorption. Plasma concentrations of the ileal brake hormones--glucagon-like peptide-1 (GLP-1) and peptide tyrosine tyrosine (PYY)--were measured to test whether release of these hormones was related to colonic fermentation. Significant amounts of 25 g and 50 g glucose, and of the bread and rice meals were fermented rather than absorbed, as judged by the increases in end-expiratory H2. Serum acetate concentrations were significantly higher in SB patients than in healthy controls. The orocecal transit times of all test meals ranged from 15 to 120 min. GLP-1 and PYY releases in SB patients were significantly higher than in healthy volunteers. They were mutually parallel and paralleled the increase in insulin. They were not related to ongoing fermentation or to intraluminal carbohydrate content per se, but most probably to absorption of glucose in the distal bowel. In conclusion, well-adapted SB patients had pronounced small intestinal malabsorption of carbohydrate, even after ingestion of small amounts of easily absorbable carbohydrates. A fast small intestinal spreading of carbohydrates, once in the small intestine, and a spill-over to the colon seem to explain the data best.

Fermentability of an enzymatically modified solubilised potato polysaccharide (SPP)

OBJECTIVE

To study processing and fermentability in the human gastro-intestinal tract of a newly isolated, enzymatically modified, soluble, and highly concentrated (> 80% dietary fibres) solubilised potato fibre (SPP).

SETTING

Gastroenterological laboratory. DESIGN, SUBJECTS AND INTERVENTIONS: Seven healthy volunteers ingested in random order on seven different days: 20 g SPP; bread made of 180 g wheat flour served with 20 g raw SPP; bread baked of 180 g wheat flour and 20 g SPP; bread made from 180 g what flour; 20 g lactulose; 20 g oat bran; and 20 g wheat bran. The hydrogen breath test was used to evaluate oro-coecal transit time (OCTT) and fermentation.

RESULTS

Fermentation of SPP yielded a measurable increase in end-expiratory H2. The total incremental increase in end expiratory H2 due to SPP was unaffected of whether SPP was served alone, as the raw flour served with bread, or baked into bread. The OCTT for raw SPP was significantly delayed compared to lactulose (P = 0.01). The OCTT for SPP baked into bread was significantly delayed compared to raw SPP (P = 0.01), indicating that SPP may be used as a marker of oro-coecal transit time for as well the fluid phase as the solid phase of a meal.

CONCLUSIONS

SPP is a fermentable, highly concentrated soluble fibre source. Baking SPP did not interfere with the fermentable properties. Thus, SPP may be interesting as a fibre-supplement in fibre-poor diets. The change in oro-coecal transit time for SPP, depending on the composition of the total meal, makes SPP interesting as a marker in studies of gastrointestinal transit.

Increased nitric oxide production in collagenous and lymphocytic colitis

The production of nitric oxide (NO) is increased in active ulcerative colitis and in Crohn's disease. We have studied NO production in collagenous colitis (CC) and lymphocytic colitis (LC), both of which are inflammatory bowel disorders of unknown aetiology. NO levels were measured directly in gas sampled from the colon during colonoscopy. Plasma levels of NO metabolites (nitrate/nitrite) were also measured. Luminal NO levels were more than 100 times higher in patients with CC compared with controls. In addition, plasma levels of nitrate/nitrite were increased in the patients as compared with controls. Measurements of NO directly in the colon or its oxidation products in plasma may be a helpful tool in further understanding the role of NO in the pathophysiology of CC and LC. Moreover, it is tempting to speculate that these measurements could be clinically useful in the diagnosis and therapy monitoring of these two inflammatory bowel diseases.

Maldigestion and colonic fermentation of wheat bread in humans and the influence of dietary fat

A fraction of wheat bread is malabsorbed in healthy humans. The malabsorbed fraction is bigger than what can be accounted for by in vitro measurements of dietary fibers and resistant starch. To determine whether it is a specific fraction defined by the structure of the starch molecule or a variable amount--which depends on the individual, the amount ingested, and other components of the meal--we performed a dose-response study on wheat bread in healthy human volunteers. Malabsorption was evaluated by using the breath-hydrogen test. Test meals were as follows: 20 g wheat bran mixed in 100 mL water; bread made from 25, 75, 100, 150, and 200 g white wheat flour (WWF); bread made from 0 g WWF and 20 g wheat bran; and bread made from 100 g WWF served with 11 or 26 g butter, corresponding to 20% or 35% of energy from fat in the meals. Three of seven volunteers malabsorbed a fraction of the bread made from 25 g WWF and five of seven a fraction of the bread made from 75 g WWF. All volunteers malabsorbed a fraction of the 100-g WWF bread, Bread made from 180 g WWF and 20 g wheat bran resulted in a breath-hydrogen response of the same magnitude as that from bread made from 200 g WWF alone. The 100-g WWF bread + 11 g butter resulted in a significantly higher breath-hydrogen response than did the bread alone, whereas the 100-g WWF bread + 26 g butter resulted in an average response of the same magnitude as that from bread alone. We conclude that the malabsorbed fraction of wheat bread was dependent on the amount ingested, the composition of the meal, and individual gastrointestinal handling. Fermentation of wheat bran resulted in a very low breath-hydrogen response compared with lactulose or wheat bread. Addition of 11 g butter to the bread seemed to increase the malabsorbed fraction of the starch, an effect that was abolished when the amount of butter was increased to 26 g.

A review of 20 years of jejunoileal bypass

BACKGROUND

The long-term effects of jejunoileostomy for morbid obesity were studied 15-20 years after surgery, in 60 patients.

METHODS

A total of 141 patients underwent surgery during the years 1973 to 1979. Thirty-four (24%) had had bowel continuity reestablished because of side effects. Eight (5.6%) were dead, 4 (2.8%) had emigrated, and 11 (7.8%) lived in remote areas, leaving 84 patients for follow-up. Sixty of these patients agreed to participate in the study. Seventy-seven per cent of the study population were women, with a mean age of 50 years.

RESULTS

The average weight loss was 50.2 kg; only one patient had regained the preoperative weight. The average weight was 84.2 kg. Reported side effects were 1) gastrointestinal: diarrhoea (61.7%), bad defecation smells (60%), and meteorism (11.7%), and 2) systemic: arthralgia (18.3%) and symptomatic nephro/cholelithiasis (18.3%). Forty-two patients (70% of the participants) found the results acceptable/satisfactory. Nine patients (15%) had vitamin B12 injections regularly; another 22 (35%) were found to have a low cobalamin level, and 35 patients (58%) had reduced P-magnesium. The 25-hydroxycholecalciferol level was low in 26 patients (43%), parathyroid hormone values were increased in 18 (30%). Fifty-seven patients (95%) had a P-carotene value lower than the normal limit.

CONCLUSION

These results stress the need for continuous control and supplementary therapy.

Glucagon-like peptide 1 undergoes differential tissue-specific metabolism in the anesthetized pig

Glucagon-like peptide 1 (GLP-1) metabolism was studied in halothane-anesthetized pigs (n = 7) using processing-independent (PI) and COOH-terminal (C) radioimmunoassays (RIA) and an enzyme-linked immunosorbent assay (ELISA) specific for biologically active GLP-1. Renal extraction of endogenous GLP-1 was detected by PI-RIA (33.1 +/- 13.3%) and C-RIA (16.0 +/- 6.3%) and by all assays during GLP-1 infusion (ELISA, 69.4 +/- 6.3%; PI-RIA, 32.6 +/- 7.3%; C-RIA, 43.7 +/- 3.4%), indicating substantial fragmentation. Hepatic and pulmonary degradation were undetectable under basal conditions, but exogenous GLP-1 elimination by the liver (43.6 +/- 8.9%) and lungs (10.1 +/- 3.2%) was measured by ELISA, suggesting primarily NH2-terminal degradation. Endogenous GLP-1 extraction by the hindleg was only detected by C-RIA (16.0 +/- 6.3%). During GLP-1 infusion, greater hindleg extraction was measured by ELISA (38.5 +/- 6.8%) and C-RIA (33.0 +/- 6.4%) than by PI-RIA (11.4 +/- 3.2%), indicating limited degradation at each terminus or more substantial COOH-terminal degradation. A shorter (P < 0.01) plasma half-life was revealed by ELISA (1.5 +/- 0.4 min) than by PI-RIA (4.5 +/- 0.6 min) or C-RIA (4.1 +/- 0.5 min). Metabolic clearance rates measured by PI-RIA (20.0 +/- 3.8 ml.min-1.kg-1) and C-RIA (15.5 +/- 1.6 ml.min-1.kg-1) were shorter (P < 0.01) than that measured by ELISA (106.8 +/- 14.7 ml.min-1.kg-1). Tissue-specific differential metabolism of GLP-1 occurs, and NH2-terminal degradation, rendering GLP-1 inactive, is particularly important in its clearance.

Effects of oral contraceptives on plasma neutral amino acids and cholesterol during a menstrual cycle

OBJECTIVE

Concentrations of plasma neutral amino acids, i.e. threonine, serine, asparagine, glycine, alanine, citrulline, alpha-aminobutyric acid, valine, methionine, isoleucine, leucine, tyrosine, phenylalanine, and tryptophan, and serum cholesterol, were determined at the follicular (Day 4), mid-cycle (Day 16) and luteal (Day 25) phases of the menstrual cycle in 15 users of the new generation of combined oral contraceptives (OC), 11 on multiphase combined OC, and 17 controls.

RESULTS

The controls showed a decrease in the sum of amino acids to 95% at mid-cycle and 90% in the luteal phase relative to the follicular phase, and a significant decrease in the tyrosine level at the luteal relative to the follicular phase. Since there was no significant difference between the two OC subgroups in the levels of the specified variables at either of the phases, the two groups were considered together. The sum of amino acids in the OC group decreased to 89% at mid-cycle and 91% at the luteal phase relative to the follicular phase, indicating less metabolic effect than reported for older OC formulations. Compared to the controls, the OC group showed significant increased threonine level at the luteal phase, decreased glycine levels at mid-cycle and the luteal phases, decreased citrulline level at mid-cycle, and markedly decreased tyrosine levels at the mid-cycle and luteal phases. Neither total nor high density lipoprotein (HDL) cholesterol differed significantly between the control and OC groups.

CONCLUSION

The results suggest that the metabolic effects of the new generation combined OC on neutral amino acids and cholesterol are only modest to slight, except for the effect on tyrosine, the brain noradrenaline precursor, which may cause disturbances of various noradrenaline-mediated central functions in susceptible subjects.

Medical examiners' attitudes toward organ procurement from child abuse/homicide victims

Solid organ transplant provides lifesaving therapy for infants and children with otherwise terminal diseases, but it is severely limited by donor organ supply. Medical examiners perform a pivotal role in the organ procurement process by determining whether a "heartbeating cadaver" on life support is a medicolegally suitable donor. This descriptive questionnaire study assesses medical examiner practice and behavior regarding organ procurement from child abuse/homicide victims. Obtaining forensic evidence for judicial purposes and releasing organs to children awaiting transplantation are not necessarily conflicting values. Greater than 60% of medical examiners sampled would agree to release organs from abuse/homicide victims in the scenarios presented here if provided with requested information. Further confronting the origins of variable medical examiner practice in this area might result in the availability of additional solid organs for pediatric transplantation.

Tyrosine metabolism in users of oral contraceptives

Brain noradrenaline takes part in the regulation of several brain functions. The formation of brain noradrenaline depends on brain tyrosine (Tyr) levels, which associates with the ratio in plasma of Tyr to other large, neutral amino acids (LNAA). Tyr metabolism has been studied in users of the new generation combined oral contraceptives (OC) and comparable controls at the follicular, mid-cycle, and luteal phases of the menstrual cycle. OC users showed significantly increased plasma Tyr transaminase activity, and significantly decreased plasma Tyr and Tyr/LNAA levels at mid-cycle and luteal phase, whereas plasma total 3-methoxy-4-hydroxyphenylglycol (MHPG) was not affected. Following an oral protein load, the area under the curve in plasma of Tyr and Tyr/LNAA in OC users at the luteal phase were 43% and 29%, respectively, of control levels. The results suggest that the decreased Tyr availability to the brain in OC users may result in a substrate-limited reduction of brain noradrenaline formation, which, secondarily, may contribute to disturbances of mood, coping mechanisms, and appetite in susceptible subjects.

Intestinal transport and fermentation of resistant starch evaluated by the hydrogen breath test

OBJECTIVE

To study fermentability of different samples of resistant starch (RS), compared to one another and to lactulose, and to study the effect on gastric emptying of addition of RS to test meal. Finally to study if adaptation to RS results in a measurable change in fermentation pattern, (H2/CH4 production). Sources of RS: Raw potato starch (RPS), 58% RS; corn flakes (CF), 5% RS; hylon VII high amylomaize starch, extrusion cooked and cooled (HAS) 30% RS; highly retrograded hylon VII high amylomaize starch (HRA) 89% RS.

DESIGN

(1) Fermentation: seven healthy volunteers ingested in randomized order 50 g RPS, 100 g CF, 75 g HAS, 25 g HRA. End-expiratory H2/CH4 was measured every 30 min for 12 to 22 hours post-ingestion as a measure of fermentation. A dose-response study of RPS, 5, 10, 25, 50, 75 and 100 g was performed. (2) Adaptation: In five 3-week periods seven volunteers added daily to their usual diet 50 g of either RPS, HAS, oat bran, wheat bran or common maize starch. The polysaccharides were administered in randomized order. The test periods were separated by 1 week's wash out. Basic end-expiratory H2/CH4 was measured once a week prior to and during the test periods. (3) Gastric emptying: The rate of increase in blood glucose was measured after test meals consisting of 50 and 100 g of RPS, 50 g HAS and 50 g glucose dissolved in a gel, alone, and mixed with 25 g of RPS. As controls we chose wheat bran and oat bran.

RESULTS

(1) We found that RPS is fermentable, although the cumulated excessive H2 production after 50 g RPS corresponding to 29 g RS was clearly less than after 10 g lactulose. The time from ingestion of RPS to a sustained increase in end-expiratory H2 (apparent transit time; 5-11 h) was longer than lactulose (1-4 h), indicating either a slow passage through the small intestine or a slow fermentation rate. 100 g of corn flakes (4.6 g RS) resulted in a measurable increase in H2 production, equivalent to 10-20 g RPS, whereas neither of the two samples of hylon VII high amylomaize resulted in any significant increase in H2 production. The dose-response study with RPS showed that even 5 g of RPS resulted in a measurable increase in end-expiratory H2, and increasing doses from 5 g to 100 g resulted in a seemingly exponential increase in H2 production. (2) 3 weeks' daily administration of HAS resulted in a slightly elevated increase in basic end-expiratory H2, although the increase did not reach statistical significance. RPS resulted in a sustained increase in basic end-expiratory H2. Both RS samples increased measurable end-expiratory CH4 in volunteers with measurable CH4 production after a lactulose load, but 3 weeks' daily challenge with these slowly fermentable substrates did not increase measurable CH4 in volunteers, who prior to the study only produced CH4 intermittently. (3) The rate of increase in blood sugar was unaffected by addition of RS or non-starch-polysaccharides to the test meal, indicating that addition of the polysaccharides does not affect gastric emptying.

CONCLUSIONS

A fraction of RPS is resistant to digestion in the small intestine, and it is fermentable by the colonic microbial flora. RS from CF, HAS and RPS give very different H2 responses, either due to differences in digestion patterns or fermentation patterns. Short-term adaptation (3 weeks) to HAS or RPS does not change the H2/CH4 response. RS does not affect gastric emptying of a test meal consisting of glucose dissolved in a gel.

Meta-analysis of second-line antirheumatic drugs: sample size bias and uncertain benefit

Placebo controlled trials of methotrexate, auranofin, penicillamine, azathioprine, sulphasalazine, gold sodium thiomalate and chloroquines were subjected to meta-analysis. The difference between drugs and placebo in the erythrocyte sedimentation rate was 8.8 mm/hr [95% confidence interval (CI), 6.4-11.3]. In multiple linear regression analyses, with the physician's global evaluation and relative change in joint tenderness count as outcome variables, a substantial sample size bias was demonstrated. The effect decreased with increasing sample size. The risk of dropping out from any cause was larger on drug than on placebo (odds ratio, 1.17; CI, 0.99-1.38). No evidence of a worthwhile effect on radiological changes was found. Of the 3439 patients, 4 went into complete remission on drug. We conclude that the benefit of second-line drugs is uncertain.

The incidence of severe duodenal anomalies in patients submitted to barium meal examination, in normals, and in different clinical subgroups

The incidence of severe duodenal anomalies (MD) has been investigated in 458 patients submitted to barium meal examination and in 176 subjects comprising various clinical subgroups. The incidence of MD in patients submitted to barium meal examination was 11.6%. The incidence of MD in 25 normals was 4%, which was not significantly different from the incidence (10%) of MD in patients with gastroesophageal reflux symptoms. Compared with in normals, MD occurred with a significantly higher incidence in 45 patients with X-ray-negative dyspepsia (24%), in 36 patients with the irritable bowel syndrome (44%), and in 37 patients with asthma (38%). It is concluded that demonstration of MD in a patient is only indicative of a possible disorder.

Autonomic nervous control of fundic secretion of somatostatin and antral secretion of gastrin and somatostatin in pigs

By selective catheterization of gastric veins, we studied the secretion of gastrin and somatostatin from the antrum and of somatostatin from the gastric fundus-corpus region in anaesthetized pigs with or without acute adrenalectomy. The secretion was studied during electrical stimulation of the vagus nerves and the splanchnic nerves and simultaneous irrigation of gastric lumen with fluids of high, low, and neutral pH. The corpus-fundus somatostatin response to vagal stimulation was biphasic with a short-lasting initial increase followed by a lasting inhibition, which was little influenced by intraluminal pH or adrenalectomy. In pigs with intact adrenals, antral somatostatin secretion was increased by vagal stimulation, whereas in adrenalectomized pigs, the effect was inhibitory. The vagally induced inhibition was abolished when the intragastric pH was kept at pH 2. The antral gastrin secretion was strongly stimulated by vagal stimulation. The magnitude of the secretory response was inversely related to the pre-stimulatory somatostatin levels, but not to the nerve stimulation responses. Splanchnic stimulation increased arterial blood pressure and gastric blood flow, but had inconsistent effects on somatostatin and gastrin secretion.

Radioimmunoassay, pharmacokinetics, and neuronal release of gastrin-releasing peptide in anesthetized pigs

Using a newly developed radioimmunoassay for porcine gastrin-releasing peptide in plasma, we studied the pharmacokinetics of this peptide after infusing it into pigs at two dose levels. The disappearance of the peptide from plasma was characterized by two components, a fast one (t 1/2 1.4 min) and a slow one (t 1/2 6.6 min). With the same assay the release of gastrin releasing-peptide from the stomachs of 8 pigs that had been catheterized for selective sampling of fundic and antral blood was studied during vagal and splanchnic stimulation with or without acute adrenalectomy at neutral, acidic, and alkaline intragastric pH. Electrical stimulation of the vagal nerves resulted in a marked increase in both antral and fundic gastrin-releasing peptide release, whereas splanchnic stimulation was without effect. The effects of nerve stimulation were neither influenced by intragastric pH nor by adrenalectomy. Because of its presence in nerves in all layers of the gastric wall, its potent effect on gastrin release, and its release after vagal stimulation, gastrin-releasing peptide is likely to play a role in the vagal control of gastrin release, gastric motility, and acid secretion.

Content and gel filtration profiles of glucagon-like and somatostatin-like immunoreactivity in human fundic mucosa

Biopsies from the fundic gastric mucosa of eight human subjects were extracted with acid-ethanol and analyzed for somatostatin- and glucagon-like immunoreactivity using region-specific RIAs. Five extracts were studied by gel filtration. The glucagon content was close to the detection limit in all extracts, and none of the known glucagon components could be identified by gel filtration. The concentration of somatostatin-like immunoreactivity was 17.4 +/- 2.0 pmol/g wet wt, and the immunoreactivity was distributed among four well defined peaks, two of which corresponded to somatostatin 1-14 and 1-28, respectively.

Nervous control of gastro-pancreatic somatostatin secretion in pigs

The influence of the autonomic nervous system on the secretion of somatostatin from the antral and the fundic parts of the stomach and from the pancreas of the pig was investigated in experiments involving electrical stimulation of the vagal nerves and the splanchnic nerves in (1) intact, anesthetized pigs and (2) isolated perfused preparations of (a) antrum with intact vagal supply, (b) pancreas with intact vagal supply, (c) pancrease with intact sympathetic supply. The results clearly demonstrated that parasympathetic activity inhibits D-cell function in all gastro-pancreatic tissues; antral gastrin secretion was inversely correlated to somatostatin secretion and it is suggest that antral D-cell secretion participates in the control of gastrin secretion; the inhibitory effect of Gastric Inhibitory Polypeptide (GIP) as well as intraluminal HCl on gastrin secretion may be exerted via the stimulatory effect of both on somatostatin secretion. The sympathetic innervation of the pancreas is also clearly inhibitory to the pancreatic somatostatin secretion, whereas sympathetic nervous activity influences little the gastric somatostatin release.