The impact of prediabetes and diabetes on endothelial function in a large population-based cohort

BACKGROUND

Diabetes and prediabetes are well-recognized risk factors for cardiovascular disease (CVD) and are marked by vascular endothelial dysfunction (ED). However, there is a scarcity of thorough population-based studies examining ED in individuals with diabetes/prediabetes free from manifest CVD. Here, we examined the association between ED assessed by reactive hyperaemia index (RHI) in the finger and diabetes/prediabetes in a large middle-aged population cohort.

METHODS

Within the Malmö Offspring Study, following the exclusion of participants <30 years and participants with prevalent CVD, 1384 participants had complete data on all covariates. The RHI was calculated using pulse amplitude tonometry. ED was defined as RHI < 1.67. Multivariable logistic and linear regression models were conducted to investigate associations between ED and RHI with diabetes and prediabetes.

RESULTS

The study population had a mean age of 53.6 ± 7.6 years (53% women). In study participants with manifest diabetes (n = 121) and prediabetes (n = 514), ED was present in 42% and 25% respectively, compared to 23% in those with normal glucometabolic status. In multivariable logistic regression analyses, prevalent diabetes was significantly associated with ED (OR 1.95; 95%CI 1.57-3.39; p = 0.002), as well as with lower RHI (β-coeff. -0.087; p = 0.002). However, prediabetes showed no association with neither ED nor RHI.

CONCLUSION

In a population free from CVD, vascular endothelial dysfunction was primarily associated with manifest diabetes, but not with prediabetes, implying that finger ED may develop when diabetes is established, rather than being an early sign of glucose intolerance. Further research is needed to explore whether addressing glucose intolerance could potentially delay or prevent vascular ED onset.

Reading comprehension improvement in autism

Introduction

A subset of autistic children excel at word decoding but have difficulty with reading comprehension (i.e., the discrepant poor comprehender reading profile). Prior research suggests the Visualizing and Verbalizing (V/V) for language comprehension and thinking intervention helps improve reading comprehension in autistic children with this reading profile. Previous studies have demonstrated the role of vocabulary, memory, and social functioning in reading comprehension; however, predictors and moderators of reading comprehension within this specific profile of autistic readers have not been thoroughly explored.

Methods

In this study, we examined the effectiveness of the V/V intervention by comparing reading comprehension scores between groups and across time. Participants included a sample of autistic children (AUT-EXP; n=22) and a waitlist control group of autistic children (AUT-WLC; n=17) with reading comprehension difficulties, as well as a sample of non-autistic children (Non-AUT; n=26) (all age 8-13 years). AUT-EXP and AUT-WLC groups completed a battery of cognitive assessments during pre and post tests. We also analyzed whether cognitive assessment scores predicted reading comprehension, and examined the moderating effects of group (AUT-EXP vs. AUT-WLC) on these relationships.

Results

The AUT-EXP group significantly improved in their pre to post reading comprehension scores (t(21)=4.19, p<.001, d=.89), whereas the AUT-WLC group did not. Verbal memory significantly predicted reading comprehension, though group did not moderate relationships between cognitive test performance and reading comprehension.

Discussion

Results suggest that the V/V intervention may help improve reading comprehension for autistic children with the discrepant poor comprehender reading profile. Additionally, strategies for improving verbal memory may indirectly enhance reading comprehension in autistic children with this reading profile.

The impact of age on endothelial dysfunction measured by peripheral arterial tonometry in a healthy population-based cohort - the Malmö offspring study

BACKGROUND/AIMS

The reactive hyperaemia index (RHI) assesses endothelial function, with a proposed cut-off of <1.67 for prevalent endothelial dysfunction (ED). However, uncertainties remain about whether this cut-off is age-dependent and applicable in healthy individuals. We aimed to explore ED in relation to age within a large population-based cohort of young to middle-aged, healthy individuals.

METHODS

Within the Malmö Offspring Study, a total of 1812 subjects (50.9% women, mean age 48 ± 11 years) were included. Post-occlusion/pre-occlusion ratio of the pulsatile signal amplitudes in the non-dominant upper arm was used to calculate RHI by EndoPat®. ED was defined as RHI < 1.67. Multivariable regression models were used to explore associations between ED and age.

RESULTS

Prevalent ED was found in 534 (29.5%) participants. In subjects aged ≤30 years, ED was present in 47.4% compared to 27.6% in subjects ≥30 years (p < 0.001). In multivariable logistic regression analyses, ED was associated with younger age (p < 0.001), higher BMI (p < 0.001) and current smoking (p < 0.001). No sex differences were observed.

CONCLUSION

In a large healthy population, RHI < 1.67, an early marker of endothelial dysfunction, was more prevalent in younger individuals, implying that RHI might not be a suitable measure of endothelial function in individuals under 30 years of age. Our findings suggest that low RHI in young, healthy individuals may not necessarily indicate true ED but rather an artefact of the limited ability of young and healthy arteries to dilate post-occlusion. Therefore, the term "pseudo-ED" may be applicable to young individuals with low RHI values.

Ventricular-arterial coupling (VAC) in a population-based cohort of middle-aged individuals: The STANISLAS cohort

BACKGROUND AND AIMS

Data exploring normal values of different ventricular-arterial coupling (VAC) parameters and their association with anthropometric and cardiovascular (CV) factors are scarce. We aim to report values of two different methods of VAC assessment according to age and sex and explore their association with CV factors within a large population-based cohort of middle-aged individuals.

METHODS

For 1333 (mean age 48 ± 14) individuals participating in the 4th visit of the STANISLAS cohort, VAC was assessed by two methods [1]: arterial elastance (Ea)/end-systolic elastance (Ees) and [2] Pulse wave velocity (PWV)/Global longitudinal strain (GLS).

RESULTS

The mean values of Ea/Ees and PWV/GLS were 1.06 ± 0.20 and 0.42 ± 0.12, respectively. The two methods of VAC assessment were poorly correlated (Pearson's correlation coefficient r = 0.14 (0.08; 0.19)). Increased PWV/GLS was associated with older age and a higher degree of cardiovascular risk factors (i.e., BMI, blood pressure, LDL, diabetes, hypertension) in the whole population as well as in the parent generation. In contrast, higher Ea/Ees were associated with decreasing age, and lower prevalence of risk factors in the whole cohort but neutrally associated with risk factors in the parent generation.

CONCLUSIONS

Higher PWV/GLS is significantly associated with CV factors regardless of age. In contrast, worse Ea/Ees is associated with a better CV risk profile when considering individuals aged 30 to 70 but neutrally associated with CV factors when considering only older patients. These results may suggest that PWV/GLS should preferably be used to explore VAC. In addition, age-individualized threshold of Ea/Ees should be used.

Cerebral saturation is associated with physical activity and post-discharge mortality in heart failure patients

Background

The cross-sectional relationship between heart failure (HF) and cerebral oxygenation has been studied in the past but the prognostic significance of this relationship has been limited. Here, we aimed to assess the role of cerebral tissue oxygen saturation (SctO2) as a risk factor for HF mortality and rehospitalization as well as evaluate the association between SctO2 with physical activity in a Swedish prospective HF cohort.

Methods

Ninety-five patients hospitalized for HF (mean age 70 years; 21% women) were examined with near-infrared spectroscopy (NIRS) and screened for physical activity derived from questionnaires in the Swedish national public health survey. The median follow-up time to death and re-hospitalization was 1377 (interquartile range, 245–2392) and 293 (14–2363) days, respectively. Associations between SctO2 at rest, post-discharge mortality and re-hospitalization were analyzed using multivariable Cox regression analysis adjusted for age, sex, body-mass index, smoking, prevalence of atrial fibrillation, prevalence of diabetes and systolic blood pressure. The associations between SctO2 and self-reported physical activity were explored by using logistic regression analysis adjusted for the aforementioned risk factors.

Results

A total of 25 patients (26%) reported to be engaged in physical activity less than one hour throughout the week. In the fully adjusted Cox regression model, low SctO2 at rest was associated with post-discharge mortality (HR, 0.77; CI, 0.66–0.91; p=0.002). However, low SctO2 was not associated with post-discharge rehospitalization risk (HR, 0.94; CI, 0.88–1.01; p=0.092). In the fully adjusted logistic regression models, low SctO2 at rest was associated with decreased physical activity (&lt;1h per week), (OR 1.22; CI, 1.05–1.42; p=0.01).

Conclusion

We have demonstrated that low cerebral tissue oxygen saturation at rest is associated with post-discharge mortality in patients hospitalized for HF, independently of traditional risk factors. In addition, low cerebral tissue oxygen saturation at rest is associated with low physical activity. These findings highlight the role of cerebral saturation as a risk factor for cardiovascular prognosis, as well as underline the potential importance of taking cerebral perfusion into account when treating for heart failure.

Funding Acknowledgement

Type of funding sources: None.

Biomarkers associated with prevalent hypertension and higher blood pressure in a population-based cohort: a proteomic approach

Background

Globally, hypertension represents an enormous health issue as it is a major, yet modifiable risk factor for developing cardiovascular disease. Recently, chitinase-3-like protein 1 (CHI3L1) was shown to be positively associated with the incidence of hypertension among prehypertensive subjects, and variants of CHI3L1 gene were associated with both CHI3L1-levels and hypertension.

Purpose

To explore associations between prevalent hypertension and blood pressure, and 92 proteins with involvement in inflammation and cardiovascular disease.

Methods

Plasma samples from 1713 individuals from a Swedish population-based cohort (mean age 67.3±6.0 years; 28.9% women) were analysed with a proximity extension assay panel, consisting of 92 proteins. Prior to all analyses, subjects with prevalent cardiovascular disease, defined as having a history of prevalent coronary or stroke event, were excluded (n=189). Univariate logistic regression models were carried out exploring associations between each of the 92 proteins and prevalent hypertension, defined as systolic blood pressure ≥140 mmHg and/or a diastolic blood pressure ≥90 mmHg, or use of antihypertensive treatment (n=1168, 76.4%). Bonferroni-corrected significant associations between proteins and hypertension were further analysed using stepwise selection of covariates, namely age, body mass index, diabetes status, and cystatin C, in logistic regression models. Proteins with significant adjusted associations with prevalent hypertension were further analysed for associations with systolic and diastolic blood pressure individually in stepwise linear regression models. Complete data on all variables were available in 1527 subjects.

Results

Sixteen proteins were significantly associated with prevalent hypertension in univariate analyses. After adjustment, three proteins remained significantly associated with prevalent hypertension (i.e., CHI3L1, low-density lipoprotein receptor (LDL receptor) and tissue plasminogen activator (tPA); Table 1). In analyses of associations with systolic blood pressure, CHI3L1 and LDL receptor showed significant associations. In analyses of associations with diastolic blood pressure, CHI3L1, LDL receptor and tPA showed significant associations (Table 1).

Conclusions

Higher CHI3L1, tPA and LDL receptor levels were positively associated with prevalent hypertension after multivariable adjustment, among 1527 elderly subjects without established cardiovascular disease. Furthermore, higher CHI3L and LDL receptor levels were positively associated with mean systolic, as well as mean diastolic blood pressure in multivariable analyses.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): The Swedish Medical Research Council and The Swedish Heart and Lung Foundation

Genome-wide association meta-analysis in 652,134 participants identifies 9 novel susceptibility loci for aortic stenosis

Background

Aortic stenosis (AS) is the most common form of incident valvular heart disease. While valve replacement is effective, the absence of an approved medical therapy provides no alternatives to patients with contraindications or mild disease. An improved understanding of the genetics of AS could identify targets for pharmacological intervention.

Methods

An inverse variance-weighted, fixed effects meta-analysis of the association of 11,591,806 variants with AS was undertaken using data from 10 European cohorts totalling 652,134 participants (13,758 cases of AS). We queried publicly available datasets to characterize the functional consequences of genome-wide significant variants, conducted a phenome-wide association study to assess their association with other outcomes, and constructed polygenic risk scores to examine their association with AS. We also performed gene- and gene-set enrichment analyses, estimated genetic correlation with cardiovascular traits, and assessed whether five lipid or immunological biomarkers were causally associated with AS using Mendelian randomization.

Results

Eighteen independent variants at 16 loci attained genome-wide significance in the meta-analysis, including variants at all seven previously reported loci. Many of the significant variants were intronic or intergenic, and the phenome-wide association study revealed extensive pleiotropy with apolipoprotein B, C-reactive protein, and other cardiovascular and immunological traits. A weighted polygenic risk score composed of the 18 variants was strongly associated with AS (adjusted OR per SD, 1.38; 95% CI, 1.33 to 1.44; p=4.6×10–57), and improved the discriminatory ability for AS when added to a model that contained clinical risk factors (difference in the area under the curve p=2.0×10–11). Gene-based approaches indicated higher IL6R expression in the blood among AS cases compared to controls (p=3.1×10–6), and the association of LDLR with AS (p=2.3×10–10). Gene set analyses revealed that genes bound by the transcription factor TCF7 or micro-RNAs miR-21, miR-219, miR-491, and miR-19 were differentially expressed in the liver depending on AS status (p≤5.7×10–4), suggesting disease development may be mediated by tissue-specific transcriptional and post-transcriptional regulation. Mendelian randomization supported a causal association of five lipid and immunological biomarkers with AS, including low-density lipoprotein cholesterol (OR per mmol/L, 1.61; 95% CI, 1.48 to 1.75; p=1.3×10–30).

Conclusions

Evidence from large-scale genetic analyses indicate that lipid metabolism, inflammation, and calcification are key contributors to AS.

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): Canadian Institutes of Health Research, National Institutes of Health

High circulating levels of midregional proenkephalin A predict vascular dementia: a population-based prospective study

Midregional Pro-enkephalin A (MR-PENK A) and N-terminal Protachykinin A (NT-PTA) have been associated with vascular dementia. However, the longitudinal relationship between these biomarkers and incident dementia has not been fully investigated. In the population-based Malmö Preventive Project, circulating levels of MR-PENK A and NT-PTA were determined in a random sample of 5,323 study participants (mean age: 69 ± 6 years) who were followed-up over a period of 4.6 ± 1.6 years. The study sample included 369 patients (7%) who were diagnosed in the same period with dementia. We analyzed relationship of MR-PENK A and NT-PTA with the risk of developing dementia by using multivariable-adjusted Cox regression models adjusted for traditional risk factors. Increased plasma levels of MR-PENK A were associated with higher risk of incident vascular dementia whereas no associations were found with all-cause or Alzheimer dementia. The risk of vascular dementia was mainly conferred by the highest quartile of MR-PENK as compared with lower quartiles. Elevated levels of NT-PTA yielded significant association with all-cause dementia or dementia subtypes. Elevated plasma concentration of MR-PENK A independently predicts vascular dementia in the general population. MR-PENK A may be used as an additional tool for identifying vascular subtype in ambiguous dementia cases.

P1588Beta-blocker therapy and risk of dementia: a population-based prospective study

Introduction

Cerebral side effects have long been recognized as complications to beta-blocker treatment. However, evidence of a longitudinal relationship between the use of beta-blockers and incident dementiais still controversial.

Objective

To evaluate the longitudinal relationship between use of beta-blockers, as a class, and incident risk of all-cause dementia, vascular dementia, Alzheimer and mixed dementia.

Methods

From the prospective, population-based, Malmö Preventive Project, 18,063 individuals (mean age 68.2, males 63.4%) were included at baseline and followed for 84,506 person-years. Patients with prevalent cerebrovascular disease and dementia were excluded. In order to weight the risk of incident dementia associated with beta-blocker consumption, we performed propensity score matching analysis, resulting in 3,720 matched pairs of beta-blocker users and non-users at baseline, and multivariable Cox proportional-hazardsregression.

Results

Overall, 122 study participants (1.6%) were diagnosed with dementia over the course of follow-up. Use of beta-blockers was independently associated with increased risk of developing vascular dementia, regardless of confounding factors (HR: 1.72, 95% CI 1.01–3.78; p=0.048). Conversely, treatment with BB was not associated with increased risk of all-cause, Alzheimer and mixed dementia (HR: 1.15; 95% CI 0.80–1.66; p=0.44; HR: 0.85; 95% CI 0.48–1.54; P=0.59 and HR: 1.35; 95% CI 0.56–3.27; p=0.50, respectively).

Conclusions and relevance

We observed that use of beta-blockers, as a class, is associated with increased longitudinal risk of vascular dementia in the general elderly population, regardless of cardiovascular risk factors, prevalent or incident history of atrial fibrillation, stroke, coronary events and heart failure. Further studies are needed to confirm our findings in the general population and to explore the mechanisms underlying the relationship between use of beta-blockers and increased risk of vascular dementia.

Monitoring of cerebral oximetry during head-up tilt test in adults with history of syncope and orthostatic intolerance

Aims

We applied near-infrared-spectroscopy (NIRS) to measure absolute frontal cerebral tissue oxygen saturation (SctO2) during head-up tilt test (HUT) in patients investigated for unexplained syncope.

Methods and results

Synchronized non-invasive beat-to-beat haemodynamic monitoring, ECG, SctO2 (NIRS; normal range: 60-80%), and peripheral oxygen saturation (left hand, SpO2) were applied during HUT in a random sample of patients with unexplained syncope. Tracings of 54 patients (mean-age: 55 ± 19 years, 39% male) with negative HUT, vasovagal syncope (VVS), or orthostatic hypotension (OH) were analysed. In 44 patients HUT was diagnostic, in 10 HUT was negative. Thirty-one experienced VVS. Of these, 6 had spontaneous and 25 nitroglycerin-induced syncope. Thirteen patients had orthostatic hypotension (OH). Although there was no significant change in mean-arterial pressure from baseline to 1 min before syncope or end of passive HUT phase (-1.4 ± 13.9 mmHg; P = 0.45), there was a significant fall in SctO2 during the same period (-3.2 ± 3.2%; P ≤ 0.001). Among patients who experienced syncope, a decrease in SctO2 from 71 ± 5% at baseline to 53 ± 9% (P < 0.001) at syncope was observed. During HUT, there was a significant difference in delta SctO2 between spontaneous VVS (-4.5 ± 3.0%) and negative HUT (-1.3 ± 1.9%; P  = 0.021), but not between spontaneous VVS and OH (-5.4 ± 4.2%; P = 0.65). In spontaneous VVS, progressive decrease of SctO2 was independent of mean arterial pressure decrease (P  = 0.22).

Conclusions

Progressive decrease in cerebral tissue oxygenation independent of mean-arterial pressure may precede spontaneous vasovagal reflex during tilt. Patients experience syncope when SctO2 falls below 60%. These data confirm clinical utility of absolute cerebral oximetry monitoring for syncope investigation. We applied NIRS to measure frontal cerebral tissue oxygen saturation (SctO2) during head-up tilt test (HUT) in patients with unexplained syncope. In 44 of 54 patients, HUT was diagnostic. In patients with syncope, a significant SctO2-decrease was observed. Different patterns of SctO2 can be detected.

Biomarkers of microvascular endothelial dysfunction predict incident dementia: a population-based prospective study

BACKGROUND

Cerebral endothelial dysfunction occurs in a spectrum of neurodegenerative diseases. Whether biomarkers of microvascular endothelial dysfunction can predict dementia is largely unknown. We explored the longitudinal association of midregional pro-atrial natriuretic peptide (MR-proANP), C-terminal endothelin-1 (CT-proET-1) and midregional proadrenomedullin (MR-proADM) with dementia and subtypes amongst community-dwelling older adults.

METHODS

A population-based cohort of 5347 individuals (men, 70%; age, 69 ± 6 years) without prevalent dementia provided plasma for determination of MR-proANP, CT-proET-1 and MR-proADM. Three-hundred-and-seventy-three patients (7%) were diagnosed with dementia (120 Alzheimer's disease, 83 vascular, 102 mixed, and 68 other aetiology) over a period of 4.6 ± 1.3 years. Relations between baseline biomarker plasma concentrations and incident dementia were assessed using multivariable Cox regression analysis.

RESULTS

Higher levels of MR-proANP were significantly associated with increased risk of all-cause and vascular dementia (hazard ratio [HR] per 1 SD: 1.20, 95% confidence interval [CI], 1.07-1.36; P = 0.002, and 1.52; 1.21-1.89; P < 0.001, respectively). Risk of all-cause dementia increased across the quartiles of MR-proANP (p for linear trend = 0.004; Q4, 145-1681 pmol L^-1 vs. Q1, 22-77 pmol L^-1 : HR: 1.83; 95%CI: 1.23-2.71) and was most pronounced for vascular type (p for linear trend = 0.005: HR: 2.71; 95%CI: 1.14-6.46). Moreover, the two highest quartiles of CT-proET-1 predicted vascular dementia with a cut-off value at 68 pmol L^-1 (Q3-Q4, 68-432 pmol L^-1 vs. Q1-Q2,4-68 pmol L^-1 ; HR: 1.94; 95%CI: 1.12-3.36). Elevated levels of MR-proADM indicated no increased risk of developing dementia after adjustment for traditional risk factors.

CONCLUSIONS

Elevated plasma concentration of MR-proANP is an independent predictor of all-cause and vascular dementia. Pronounced increase in CT-proET-1 indicates higher risk of vascular dementia.

Inadequate treatment of depression after myocardial infarction

OBJECTIVE

The objective of the study was to investigate the prevalence of depressive symptoms and the self-reported psychiatric treatment after myocardial infarction.

METHOD

Depressive symptoms and medication were studied in 85 consecutive acute myocardial infarction patients during 18 months follow-up. Depressive symptoms were assessed using the Beck Depression Inventory (BDI).

RESULTS

The proportion of patients with depressive symptoms (BDI >/= 10) was 21.2% while in hospital, 30.0% at 6 months and 33.9% at 18 months. At 18 months, none of the patients were receiving adequate antidepressive medication. There were eight patients with BDI scores corresponding to moderate/severe depression (BDI >/= 19). Six of these patients were receiving benzodiazepine medication and two of them had been treated in the mental health care system after the myocardial infarction.

CONCLUSION

There seems to be considerable problems in the diagnosis and/or treatment of depression after myocardial infarction.

Pharmacokinetics and pharmacodynamics of mivacurium in young adult and elderly patients

BACKGROUND

Mivacurium is hydrolyzed by plasma cholinesterase, and is therefore less dependent on liver metabolism and renal elimination than other neuromuscular blocking drugs. This might favor the use of mivacurium in elderly patients. The purpose of this study was to compare the pharmacodynamics and the pharmacokinetics of the three isomers of mivacurium and their metabolites in young adult and elderly patients.

METHODS

Sixty-four patients were included in a dose-response study, in which 32 young adults and 32 elderly patients received one of four doses of mivacurium. An additional bolus dose of mivacurium to a total of 0.1 mg/kg was given followed by a continuous infusion adjusted to maintain a 91-99% neuromuscular block. The times to maximum block and different levels of recovery were measured using mechanomyography and train-of-four (TOF) nerve stimulation. Thirty-two patients were randomly selected for the pharmacokinetic study. Venous samples were taken for determination of the three mivacurium isomers and the metabolites.

RESULTS

The estimated ED95 were 0.053 and 0.061 mg/kg in young adults and elderly patients, respectively (NS). The median infusion rate did not differ, but duration to a TOF ratio of 0.7 was significantly longer in elderly patients than in young adult patients (21.0 vs. 16.5 min). No statistically significant difference between the age groups in clearance and elimination half-life of the isomers was seen. The half-lives of the metabolites were significantly prolonged in the elderly patients.

CONCLUSION

There were no significant differences in the potency or infusion requirements between the adult and elderly patients, but the rate of recovery was significantly, though only moderately prolonged, in the elderly patients. No significant difference in clearance was seen but the elimination half-lives of the metabolites was longer in the elderly patients.

Promoting breastfeeding in rural Gambia: combining traditional and modern knowledge

Sub-optimal breastfeeding practices still prevail in many countries, especially in traditional rural communities. Despite high breastfeeding initiation rates and long total duration of breastfeeding, exclusive breastfeeding is a rare practice. In the present study, quantitative methods were used to identify current infant feeding practices in 12 rural communities in The GAMBIA: Results indicated that delayed initiation of breastfeeding, prelacteal feeding and failure to practice exclusive breastfeeding were widespread. Qualitative data further indicated that current beliefs and practices were strongly influenced by traditional beliefs and practices. These were kept very much alive by elders, both women and men, including husbands. The results also showed an unexpected support for bottle-feeding from both male and female elders who considered it part of the modernization process. A strategy for promoting early initiation of breastfeeding, feeding of colostrum and exclusive breastfeeding for 6 months in rural communities should therefore incorporate traditional beliefs and practices into modern messages on optimal breastfeeding. Traditional beliefs and practices in the study setting that could be used in this way included knowledge from the population's acquaintance with the newborns of their livestock. It also included the traditional practice of mothers taking their very young children with them when going to work in the fields. The paper suggests such a strategy by developing a matrix to establish linkages between modern and traditional knowledge on a specific practice. Such linkages facilitate the acceptance of recommendations on infant feeding by mothers in these communities. The strategy recommends an expanded target group to include elders and husbands, as the data show that these groups are highly influential in matters regarding patterns of child feeding.

Proteinase inhibitors induce selective stimulation of human trypsin and chymotrypsin secretion

Among the variety of signals stimulating pancreatic secretion, cholecystokinin (CCK) and related hormones are assumed to be responsible for modulating proteinase output. In some species, intraduodenal tryptic activity has to be abolished to demonstrate feedback-induced CCK release. The aim of this study was to investigate in vivo effects of modest inhibition of intraduodenal proteolytic enzymes on the secretion patterns of pancreatic enzymes and plasma CCK concentrations. Two inhibitors (Kunitz trypsin inhibitor and Bowman-Birk inhibitor) were applied. Intermittent sampling of plasma nd duodenal juice was performed during intraduodenal saline and inhibitor instillations in six healthy volunteers. Enzyme activities and concentrations were determined in the duodenal samples and expressed as percentage of basal values. Instillation of Kunitz trypsin inhibitor caused an increase in trypsin and the pancreatic secretory trypsin inhibitor (PSTI), without changes in plasma CCK. This result demonstrates, for the first time, that pancreatic exocrine secretion of trypsin and chymotrypsin is regulated by different mechanisms. Bowman-Birk inhibitor additionally stimulated the secretion of chymotrypsin and carboxypeptidase A and B and increased plasma CCK. Elastase 1 and amylase secretions were not increased by either instillations. Although the inhibitors have similar in vitro inhibition patterns, their in vivo effects are different. The nonparallel secretion of proteinases (trypsin, chymotrypsin and elastase 1) supports the view of a complex system involved in feedback regulation of human pancreatic exocrine secretion, including signals other than CCK.

Inhibitor-stimulated non-parallel pancreatic secretion in man: hormonal and neural regulation?

BACKGROUND

We wanted to study whether a total inhibition of tryptic activity in the duodenum would induce a cholecystokinin (CCK)-dependent increase in pancreatic exocrine proteinase secretion.

METHODS

Concentrations of CCK and activities and concentrations of pancreatic enzymes were measured in human plasma and duodenal juices, respectively, collected during continuous intraduodenal instillations of proteinase inhibitors, with and without intravenous atropine administration.

RESULTS

Inhibitor instillation totally abolished tryptic activity and reduced the chymotryptic and elastase (1 and 2) activities by 95-100%. The inhibitors caused a rapid increase in the concentrations of trypsin, chymotrypsin, and pancreatic secretory trypsin inhibitor (PSTI) but had only a slight or no effect on amylase and elastase 1 secretion. An enhanced secretion of PSTI lends support to a possible connection between PSTI (resembling the monitor peptide causing CCK release in rats) and the enzyme secretion in man. CCK increased from 7 to 12-13 pmol/l. Intravenous atropine almost completely blocked the inhibitor-stimulated enzyme and PSTI secretion and reduced amylase activity by 50%. A further significant (P = 0.002) increase in the inhibitor-induced CCK output was found during atropine administration, as compared with the test situation without atropine.

CONCLUSION

The inhibitor-induced pancreatic secretion during total inhibition of tryptic activity shows a non-parallel secretion requiring different signals for different enzymes. The increase in plasma CCK levels indicates that CCK is feedback-regulated by both an inhibitor-mediated decrease in duodenal enzyme activity and a further decrease in pancreatic enzyme secretion by atropine.

Update on newer neuromuscular blocking drugs

The development of new non-depolarizing neuromuscular blocking drugs starting with the introduction of the intermediate-acting agents atracurium and vecuronium has made it possible to avoid the use of succinylcholine for elective cases. Recently 4 new drugs have become available; the short-acting mivacurium, the intermediate-acting rocuronium and the 2 long-acting drugs doxacurium and pipecuronium. The pharmacokinetic and pharmacodynamic profile of these drugs are reviewed in this paper.

Platelet selenium as indicator of wheat selenium intake

The effect of an increased intake of wheat selenium (Se) on platelet Se, serum Se, whole-blood Se, and glutathione peroxidase (GSH-Px) levels was investigated in 14 healthy Norwegian females (age 21-53 years). The intake of 60 micrograms Se per day as wheat Se, for six weeks, significantly increased the platelet Se (mean +/- SEM) from 9.1 +/- 1.1 mumol/L to 11.4 +/- 0.9 mumol/L, the serum Se from 1.43 +/- 0.18 mumol/L to 1.63 +/- 0.25 mumol/L, and the whole blood Se from 1.77 +/- 0.18 mumol/L to 2.01 +/- 0.18 mumol/L. The increase in percent of initial Se values was twice as high for platelets as for serum and whole blood. The GSH-Px levels were not altered during the experiment. Platelet Se was not significantly correlated to the Se intake initially. At the end of the experimental period, the Se in platelets reflected the total Se intake, but not with a simple linear correlation. No significant correlation between the total Se intake and the Se concentration in whole blood or serum was found.

L-tryptophan supplementation does not improve running performance

In 1988 Segura and Ventura (14) reported that 1.2 g of L-Tryptophan (L-TRY) supplementation increased total exercise time by 49.4% when the subjects were running at 80% of maximal oxygen uptake (VO2max). In human performance research, acute improvements of that category are rather uncommon. Both for this reason and because ingestion of purified L-TRY may have adverse effects, it seemed pertinent to repeat the investigation of Segura and Ventura. Forty-nine well-trained male runners, aged 18-44, with an average maximal aerobic power of 66 (57-78) ml.kg-1.min-1, participated in a randomized double blind placebo (P) study. Each subject underwent four trials on the treadmill. The first two served as learning experience, including measurement of VO2max and anaerobic threshold. During the last two trials the subjects ran until exhaustion at a speed corresponding to 100% of their VO2max-first an initial trial and then after receiving a total of 1.2 g L-TRY or P over a 24 hour period prior to the run. No significant difference between the improvements in the L-TRY and P group could be demonstrated. It is concluded that oral L-TRY supplementation does not enhance running performance.

Raw soybeans stimulate human pancreatic proteinase secretion

Intraduodenal instillation of raw soybeans stimulated pancreatic proteinase secretion in humans. Raw soybeans almost abolished the activity of chymotrypsin and severely reduced (50%) the tryptic activity. Immunoreactive tryptic and chymotryptic material simultaneously appeared in amounts 2 to 4 times basal concentrations. This increase, demonstrated with rocket immunoelectrophoresis, was begun within the first 10 min of soybean instillation. The enhanced secretion also persisted throughout the succeeding saline instillation, and it is suggested that the presence of Kunitz trypsin inhibitor contributed to this postprandial stimulation. An amidase that hydrolyzes low-molecular-weight substrates (i.e., benzoyl-arginine p-nitroanilide) was found in raw soybeans. Its low activity was not assumed to substantially bias standard trypsin assays. The increased proteinase secretion was, as previously published, not preceded by an elevated plasma cholecystokinin concentration. The raw soybeans also caused a nonparallel secretion of amylase and proteinases. Nervous, perhaps cholinergic, regulation mediates the inhibitor-stimulated proteinase secretion in humans. This stimulation yields both a general increase of proteinases and also a specific inhibitor-resistant trypsin. This is consistent with the physiologic need for proenzyme-activation in the presence of inhibitors and for restoration of the proteolytic capacity of the duodenal juice.

Supplementation with wheat selenium induces a dose-dependent response in serum and urine of a Se-replete population

In spite of a rather modest dietary intake of selenium (80 micrograms/10 MJ), Norwegian serum Se levels are among the highest in Europe. As part of an ongoing study of Se bioavailability, effects of different doses of wheat Se were investigated in eighteen healthy, Norwegian women. The participants were given Se-rich bread providing 100, 200 and 300 micrograms Se daily for 6 weeks. About 50% of the Se intake was excreted in the urine by week 6, compared with 67% before the intervention started. Serum Se increased by 20, 37 and 53 micrograms/l respectively, in the three group (P less than 0.001). The blood response and renal clearance results compare well with data obtained from less Se-replete populations, and support the hypothesis that selenomethionine from the diet is incorporated into a non-specific amino acid pool. Our study indicates that the intake of wheat Se is the main determinant of blood Se levels in Norway.

Nicotine intake and dependence in Swedish snuff takers

Two studies examining nicotine intake in users of Swedish moist oral snuff are reported. Absorption form a single pinch (2 g) in ten users after overnight abstinence was fairly rapid. The increment in plasma nicotine concentrations averaged 9.9 ng/ml (SD 6.5) after 10 min and peaked at 14.5 ng/ml (SD 4.6) shortly after discarding at 30 min. Among groups of habitual snuff takers (n = 27) and cigarette smokers (n = 35) studied on a day of normal snuffing/smoking, peak blood nicotine levels after use were similar [averaging 36.6 ng/ml (SD 14.4) and 36.7 ng/ml (SD 16.1), respectively], but there was a tendency to higher cotinine levels in the snuffers (399.2 ng/ml versus 306.3 ng/ml). The snuff takers and cigarette smokers reported similar levels of subjective dependence on tobacco. Epidemiological study of Swedish snuff users could clarify whether the cardiovascular risks of tobacco are attributable to nicotine or to other smoke components, as in their case nicotine intake is not accompanied by combustion products.

Characterization of a human trypsin resistant to Kunitz soybean trypsin inhibitor. Studies of duodenal juices after tube instillation of raw soybean extract

Human duodenal juices collected during tube instillation of raw soybean extract into the duodenum contained free trypsin and free Kuntiz soybean trypsin inhibitor (KTI) in the simultaneous presence of trypsin-KTI complexes. It has previously been suggested that this KTI-non-inhibitable trypsin has a general resistance to serine protease inhibitors. Four different trypsin forms have been found and partly characterized by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and isoelectric focusing followed by Western immunoblotting or enzyme staining. In addition, crossed immunoelectrophoresis and affinity chromatography with antibody-coupled gels have been used for identification of free and inhibitor-complexed trypsin.

Raw soy and purified proteinase inhibitors induce the appearance of inhibitor-resistant trypsin and chymotrypsin activities in Wistar rat duodenal juice

Rats were fed raw soybeans or purified soybean proteinase inhibitors by tube to see whether they were able to produce inhibitor-resistant trypsin, as previously demonstrated in humans. Their duodenal chyme contained only 20-50% of the enzymatic activities of animals fed bovine serum albumin (BSA) as test protein. However, both tryptic and chymotryptic activities had considerable resistance to low- and high-molecular-weight inhibitors of serine proteinases. In particular, the tryptic activity demonstrated a high degree of inhibitor resistance. Human alpha 1-antitrypsin and lima bean inhibitor in amounts that inhibited bovine serum albumin-induced trypsin completely caused only 2-12% inhibition of the raw soybean-induced tryptic activity. The inhibitor-resistant tryptic and chymotryptic activities after raw soybean instillation might be caused by the Bowman-Birk and Kunitz trypsin inhibitors. The physiologic significance of an inhibitor-resistant trypsin might be to assure activation of other pancreatic proenzymes. The results of the present rat experiments confirm the previous findings of inhibitor-resistant trypsin in humans.

Opposite effect of cold on energetic efficiency in normal and obese Wistar rats with hypothalamic lesions

Reduced thermogenesis in brown adipose tissue (BAT) may contribute to increased energetic efficiency and obesity in rats with ventromedial hypothalamic (VMH) lesions. Thermogenic activity of BAT is a function of the environmental temperature. If a relationship exists, it follows that the increased energetic efficiency of VMH-lesioned rats likewise should be governed by temperature. We have therefore investigated the energy balance of normal and VMH-lesioned rats housed at 30 degrees C and 10 degrees C. Experiments at differing feeding levels allowed calculation of maintenance energy requirements and the net energetic efficiencies of each group. VMH-lesioned rats at thermoneutrality (30 degrees C) accumulated more body fat at all feeding levels than did normal rats. Maintenance energy requirement was reduced, but the net energetic efficiency did not differ significantly from normal. The reduced maintenance energy requirement of lesioned rats persisted at 10 degrees C. Net energetic efficiency decreased in normal rats acclimated to cold but increased in the lesioned group. The difference was significant (P less than 0.05). The cold-induced increase in interscapular brown adipose tissue (IBAT) oxidative capacity of VMH-lesioned rats was only half that of normal rats. Differences in BAT thermogenesis may be the basis for the differing temperature effects on net energetic efficiency.

Seasonal siderosis in female eider nesting in Svalbard

Specimens of female and male eider (Somateria mollissima) were collected in Svalbard. Atomic absorption analyses revealed mean hepatic iron concentrations of 280 micrograms per g wet weight 2 to 3 weeks before egg laying, 2620 micrograms per g after 2 to 3 weeks brooding and 800 micrograms per g 2 weeks after hatching. At the highest concentration, there was massive siderosis with the iron located in both parenchymal and non-parenchymal cells. No signs of liver injury were seen. The female eider fasts completely from the start of egg laying to the end of hatching. The non-parenchymal iron deposits are probably the result of catabolism of blood and lean tissue, i.e., translocation of body iron. The parenchymal siderosis can hardly be explained by liver weight loss alone. An increased iron absorption preceding the egg laying is suggested.

The form of selenium determines the response to supplementation in a selenium replete population

In an ongoing study of selenium bioavailability, effects of supplementation with organic and inorganic forms of selenium were investigated in healthy, Norwegian women, aged 23-50 years. In phase I of the study, 58 women received 200 micrograms selenium per day either as selenite or selenium-rich pea flour for 3 months. The selenium tablets were taken together with placebo or ascorbic acid in a double blind design. Initial blood and serum selenium concentrations were 153 +/- 15 micrograms/l and 117 +/- 12 micrograms/l, respectively. These are average values for Norwegians. Indications of increased blood levels were seen in all groups, but the rise reached significance only for the subgroup receiving selenite and ascorbic acid, 14 micrograms/l, P less than 0.05. On the other hand, selenium analysis of 72-h urine samples confirmed that at an average 50 per cent of the selenium supplements had been absorbed. In phase II of the study, 28 of the participants continued for another 5 weeks, still on 200 micrograms Se per day, but this time consuming commercially available preparations. Of four preparations that were tested, two consisted of yeast Se. Only one of these produced a significant rise in blood and serum selenium levels, 60 and 55 micrograms/l respectively. Blood glutathione peroxidase values were not affected by any supplementation. The study demonstrates that different forms of organic selenium elicit widely different responses when administered to a relatively selenium-replete population, and that the explanation for this must be sought at the metabolic level.

High and low inhibitor soybean meals affect human duodenal proteinase activity differently: in vitro comparison of proteinase inhibition

The purpose of the study was to investigate the in vitro inhibition of the proteolytic activity in samples of duodenal juice obtained during instillation of raw soybeans in humans. The results suggested the presence of an inhibitor-resistant trypsin. Practically no inhibition was obtained with phenylmethylsulfonyl fluoride, aprotinin, human alpha 1-antitrypsin or lima bean trypsin inhibitor. Specificity against synthetic substrates was different from that obtained in the absence of raw soybeans. Duodenal aspirates containing this new trypsin activity were able to further inhibit tryptic and chymotryptic activity of basal aspirates from the duodenum, demonstrating surplus amounts of inhibitors in the duodenal juice. Further incubation of trypsin-inhibitor complexes at 37 degrees C, in the presence of surplus uninhibited (trypsin and chymotrypsin) duodenal juice, restored tryptic activity. This activity was not inhibitor-resistant. The results obtained for trypsin activity based on esterase assays were confirmed by a proteolytic assay. It is concluded that the increase in tryptic activity in human duodenal juice during raw soybean infusion is due to a previously unidentified inhibitor-resistant trypsin and not due to inactivation of the inhibitors in raw soybeans.

High and low inhibitor soybean meals affect human duodenal proteinase activity differently: in vivo comparison with bovine serum albumin

The objective of this study was to investigate the effects of high and low inhibitor soybean meals on the duodenal enzyme activities and on the possible regulatory role of gastrointestinal hormones in the pancreatic response. After an overnight fast, 11 healthy volunteers received an intraduodenal infusion of saline for 60 min. This was followed by infusion of either of three test meals: extract of raw soybeans (RS), a low inhibitor soy protein isolate (SPI) or bovine serum albumin (BSA), 10 g/h for 60 min. Then saline was again given intraduodenally for 30 min. Gastric juice was collected continuously and duodenal juice and peripheral blood samples were collected every 10 min. Duodenal chymotryptic activity was severely inhibited by RS, whereas SPI and BSA increased the chymotryptic activity. Tryptic activity showed a transient reduction (55%) during RS infusion, whereas BSA and in particular SPI increased the tryptic activity. No change was seen in amylase activity. The lack of total inhibition of tryptic activity has been studied further and is the subject of the accompanying paper. The peripheral plasma levels of cholecystokinin (CCK) increased significantly during BSA but not during SPI or RS infusions. Thus, CCK levels were not increased by the inhibition of the proteolytic activity by RS in duodenal juice.

Effect of acute potassium depletion and thiazide treatment on blood glucose in the normal rat

The effect of potassium depletion and a thiazide diuretic on glucose metabolism was investigated in male rats. Potassium depletion was induced by potassium-deficient diet and ion-exchange resin by stomach tube for 5 days. Plasma and muscle potassium was reduced by 30% (P less than 0.001), and fasting blood glucose concentration was elevated by 20% (P greater than 0.025) by potassium depletion. Hydroflumethiazide 10 mg/kg given orally once daily for 8 days produced no further alteration in any parameter. We conclude that acute potassium depletion in the rat may increase fasting blood glucose concentration, whereas addition of short-term thiazide treatment does not seem to potentiate this effect.

Net protein utilization determined by rat bioassay of a protein hydrolysate and a diet for children with phenylketonuria

In a previous study (Kindt et al. 1983, 1984) it was assumed that a protein hydrolysate, devoid of phenylalanine, together with intact protein as given to children with phenylketonuria (PKU), was equivalent to egg or milk protein. One group of children was given this 'PKU protein' in amounts corresponding to the Joint FAO/WHO ad hoc Expert Committee (1973) recommendations. The results indicated that the Joint FAO/WHO ad hoc Expert Committee (1973) recommended levels of protein intake were marginal. The purpose of the present study was to evaluate whether the quality of the protein hydrolysate, together with intact protein ('PKU protein'), is equivalent to egg or milk protein. This was done using a rat bioassay. Four protein sources were used: (1) egg protein, (2) protein hydrolysate, (3) protein hydrolysate diluted with non-essential amino acids, (4) protein hydrolysate mixed with food proteins ('PKU protein'), comparable with the diet previously used (Kindt et al. 1983, 1984). The results indicated that the 'PKU protein' was of very high quality: net protein utilization (NPU) greater than 90. The protein hydrolysate alone and the protein hydrolysate diluted with non-essential amino acids gave a NPU greater than 80. The conclusion drawn from the present study is that the 'PKU protein', as used in the treatment of children with PKU, is equivalent to egg or milk protein. This supported the view that the Joint FAO/WHO ad hoc Expert Committee (1973) recommended levels of intake were marginal.

Metabolism of ochratoxin B and its possible effects upon the metabolism and toxicity of ochratoxin A in rats

A metabolic product was formed from ochratoxin B by rat liver microsomal fractions in the presence of NADPH. It was isolated from the incubation mixture by extraction, thin-layer chromatography, high-pressure liquid chromatography, and crystallization. On the basis of mass and nuclear magnetic resonance spectroscopy, the structure is suggested to be 4-hydroxyochratoxin B. The Km for the formation of 4-hydroxyochratoxin B was determined, and the hydroxylation of ochratoxin A was not altered by the presence of ochratoxin B. Rats were given ochratoxin A or B, or a mixture of both intraperitoneally. The ratios of the three metabolites, ochratoxin A, (4R)-4-hydroxyochratoxin A, and ochratoxin alpha, excreted in the urine did not change in the presence of ochratoxin B. Ochratoxin B was metabolized to 4-hydroxyochratoxin B and ochratoxin beta, but in a different ratio than for the ochratoxin A metabolites. When given intraperitoneally, ochratoxin beta was excreted within 24 h. In rats treated with ochratoxin A alone, the food intake was reduced by 50%, and histologically severe lesions, degeneration, and necrosis were observed in the proximal tubules. When ochratoxin A and B given in combination, the animals were clinically unaffected and histologically there was only slight damage of proximal tubules. These observations indicate that ochratoxin B considerably reduces the toxic effects of ochratoxin A.

Tailoring of the diet for the individual in maple syrup urine disease: long-term home dietary treatment of an adult patient with MSUD by monitoring of daily intake with a personal computer. A case report

The clinical appearance of maple syrup urine disease (MSUD) is due to reduced activity of the enzyme branched-chain alpha keto acid decarboxylase (alpha-BCKA-decarboxylase), thereby affecting the metabolism of the branched-chain amino acids (BCAA), leucine (Leu), isoleucine (Ile) and valine (Val). The aim of the therapeutic regime in MSUD is to keep the concentration of toxic metabolites within individual tolerance limits. The case of a 46-year-old female patient is reported. Energy expenditure was calculated by recording activities and indirect calorimetry. Nitrogen requirement and tolerance level of BCAA were estimated during parenteral nutrition with stepwise increasing supply of amino acids. A diet was designed within these limits, and a computer program was made to assist the patient in keeping her diet within the estimated limits.

Lack of hyperglycemic effect of chlorothiazide in normal rats fed diets with different carbohydrate content

The effect of chlorothiazide (CT) on blood glucose and liver glycogen was investigated in rats fed either a standard, a carbohydrate-rich, or a carbohydrate-poor diet. CT did not alter blood glucose concentration or liver glycogen content in rats fed the carbohydrate-rich diet. After 5 days on the carbohydrate-poor diet, an oral glucose load produced significantly smaller rate constant for glucose disappearance from blood and significantly greater area below the glucose concentration--time curve than after a standard diet, but CT did not further alter these parameters. Nor did oral CT for 19 days alter glucose tolerance. In conclusion, CT in single dose or short term studies does not seem to alter glucose metabolism in the normal male rat.

Pancreatic proteinases from man, trout, rat, pig, cow, chicken, mink and fox. Enzyme activities and inhibition by soybean and lima bean proteinase inhibitors

1. The specific activities of the trypsins and chymotrypsins, measured with synthetic substrates, varied within one order of magnitude. 2. The trout trypsin and chymotrypsin were 5-15 times as efficient in hydrolyzing casein as the remaining animals. 3. The inhibition of total caseinolytic activity in extracts of pancreatic tissue by SBTI and inhibitors in crude extracts of raw soybeans varied ten-fold. 4. The animals may be ranked as follows according to the sensitivity of the caseinolytic activity to SBTI; trout greater than fox, chicken, greater than pig greater than rat, cow greater than mink greater than man.

Problems in predicting the inhibition of human pancreas proteinases by soya bean proteinase inhibitors: in-vitro assays employing human, bovine and porcine proteinases

Extracts of seven genetically different soya bean varieties were found to give different inhibition of trypsin and chymotrypsin and total proteolytic activity in human pancreatic juice. Commercially manufactured bovine and porcine enzymes were tested against the same extracts in order to find an assay that could substitute for human enzymes. A total of 11 enzyme and substrate combinations were compared. The effects on caseinolytic activity of human pancreatic juice were considered to be the assay most relevant to human nutrition. Large differences in ranking of the varieties between enzymes and species were apparent, using a constant amount of soya bean extract in the assays. The ranking was found to depend also on the amount of soya bean extract added in the assays. These studies therefore question the relevance to man of results from assays employing bovine and porcine enzymes.