Very early life microbiome and metabolome correlates with primary vaccination variability in children

IMPORTANCE

We show that simultaneous study of stool and nasopharyngeal microbiome reveals divergent timing and patterns of maturation, suggesting that local mucosal factors may influence microbiome composition in the gut and respiratory system. Antibiotic exposure in early life as occurs commonly, may have an adverse effect on vaccine responsiveness. Abundance of gut and/or nasopharyngeal bacteria with the machinery to produce lipopolysaccharide-a toll-like receptor 4 agonist-may positively affect future vaccine protection, potentially by acting as a natural adjuvant. The increased levels of serum phenylpyruvic acid in infants with lower vaccine-induced antibody levels suggest an increased abundance of hydrogen peroxide, leading to more oxidative stress in low vaccine-responding infants.

Phosphorylation-dependent control of Activity-regulated cytoskeleton-associated protein (Arc) protein by TNIK

Activity-regulated cytoskeleton-associated protein (Arc) is an immediate early gene product that support neuroplastic changes important for cognitive function and memory formation. As a protein with homology to the retroviral Gag protein, a particular characteristic of Arc is its capacity to self-assemble into virus-like capsids that can package mRNAs and transfer those transcripts to other cells. Although a lot has been uncovered about the contributions of Arc to neuron biology and behavior, very little is known about how different functions of Arc are coordinately regulated both temporally and spatially in neurons. The answer to this question we hypothesized must involve the occurrence of different protein post-translational modifications acting to confer specificity. In this study, we used mass spectrometry and sequence prediction strategies to map novel Arc phosphorylation sites. Our approach led us to recognize serine 67 (S67) and threonine 278 (T278) as residues that can be modified by TNIK, which is a kinase abundantly expressed in neurons that shares many functional overlaps with Arc and has, along with its interacting proteins such as the NMDA receptor, and been implicated as a risk factor for psychiatric disorders. Furthermore, characterization of each residue using site-directed mutagenesis to create S67 and T278 mutant variants revealed that TNIK action at those amino acids can strongly influence Arc's subcellular distribution and self-assembly as capsids. Together, our findings reveal an unsuspected connection between Arc and TNIK. Better understanding of the interplay between these two proteins in neuronal cells could lead to new insights about apparition and progression of psychiatric disorders. Cover Image for this issue: https://doi.org/10.1111/jnc.15077.

Phosphorylation-dependent control of Activity-regulated cytoskeleton-associated protein (Arc) protein by TNIK

Activity-regulated cytoskeleton-associated protein (Arc) is an immediate early gene product that support neuroplastic changes important for cognitive function and memory formation. As a protein with homology to the retroviral Gag protein, a particular characteristic of Arc is its capacity to self-assemble into virus-like capsids that can package mRNAs and transfer those transcripts to other cells. Although a lot has been uncovered about the contributions of Arc to neuron biology and behavior, very little is known about how different functions of Arc are coordinately regulated both temporally and spatially in neurons. The answer to this question we hypothesized must involve the occurrence of different protein post-translational modifications acting to confer specificity. In this study, we used mass spectrometry and sequence prediction strategies to map novel Arc phosphorylation sites. Our approach led us to recognize serine 67 (S67) and threonine 278 (T278) as residues that can be modified by TNIK, which is a kinase abundantly expressed in neurons that shares many functional overlaps with Arc and has, along with its interacting proteins such as the NMDA receptor, and been implicated as a risk factor for psychiatric disorders. Furthermore, characterization of each residue using site-directed mutagenesis to create S67 and T278 mutant variants revealed that TNIK action at those amino acids can strongly influence Arc's subcellular distribution and self-assembly as capsids. Together, our findings reveal an unsuspected connection between Arc and TNIK. Better understanding of the interplay between these two proteins in neuronal cells could lead to new insights about apparition and progression of psychiatric disorders.

Evaluation of molecular brain changes associated with environmental stress in rodent models compared to human major depressive disorder: A proteomic systems approach

OBJECTIVES

Rodent models of major depressive disorder (MDD) are indispensable when screening for novel treatments, but assessing their translational relevance with human brain pathology has proved difficult.

METHODS

Using a novel systems approach, proteomics data obtained from post-mortem MDD anterior prefrontal cortex tissue (n = 12) and matched controls (n = 23) were compared with equivalent data from three commonly used preclinical models exposed to environmental stressors (chronic mild stress, prenatal stress and social defeat). Functional pathophysiological features associated with depression-like behaviour were identified in these models through enrichment of protein-protein interaction networks. A cross-species comparison evaluated which model(s) represent human MDD pathology most closely.

RESULTS

Seven functional domains associated with MDD and represented across at least two models such as "carbohydrate metabolism and cellular respiration" were identified. Through statistical evaluation using kernel-based machine learning techniques, the social defeat model was found to represent MDD brain changes most closely for four of the seven domains.

CONCLUSIONS

This is the first study to apply a method for directly evaluating the relevance of the molecular pathology of multiple animal models to human MDD on the functional level. The methodology and findings outlined here could help to overcome translational obstacles of preclinical psychiatric research.

Cell-Type-Specific Profiling of Alternative Translation Identifies Regulated Protein Isoform Variation in the Mouse Brain

Alternative translation initiation and stop codon readthrough in a few well-studied cases have been shown to allow the same transcript to generate multiple protein variants. Because the brain shows a particularly abundant use of alternative splicing, we sought to study alternative translation in CNS cells. We show that alternative translation is widespread and regulated across brain transcripts. In neural cultures, we identify alternative initiation on hundreds of transcripts, confirm several N-terminal protein variants, and show the modulation of the phenomenon by KCl stimulation. We also detect readthrough in cultures and show differential levels of normal and readthrough versions of AQP4 in gliotic diseases. Finally, we couple translating ribosome affinity purification to ribosome footprinting (TRAP-RF) for cell-type-specific analysis of neuronal and astrocytic translational readthrough in the mouse brain. We demonstrate that this unappreciated mechanism generates numerous and diverse protein isoforms in a cell-type-specific manner in the brain.

Fetal regional brain protein signature in FASD rat model

Fetal alcohol spectrum disorders (FASD) describe neurodevelopmental deficits in children exposed to alcohol in utero. We hypothesized that gestational alcohol significantly alters fetal brain regional protein signature. Pregnant rats were binge-treated with alcohol or pair-fed and nutritionally-controlled. Mass spectrometry identified 1806, 2077, and 1456 quantifiable proteins in the fetal hippocampus, cortex, and cerebellum, respectively. A stronger effect of alcohol exposure on the hippocampal proteome was noted: over 600 hippocampal proteins were significantly (P < .05) altered, including annexin A2, nucleobindin-1, and glypican-4, regulators of cellular growth and developmental morphogenesis. In the cerebellum, cadherin-13, reticulocalbin-2, and ankyrin-2 (axonal growth regulators) were significantly (P < .05) altered; altered cortical proteins were involved in autophagy (endophilin-B1, synaptotagmin-1). Ingenuity analysis identified proteins involved in protein homeostasis, oxidative stress, mitochondrial dysfunction, and mTOR as major pathways in the cortex and hippocampus significantly (P < .05) affected by alcohol. Thus, neurodevelopmental protein changes may directly relate to FASD neuropathology.

Chemogenomic analysis reveals key role for lysine acetylation in regulating Arc stability

The role of Arc in synaptic plasticity and memory consolidation has been investigated for many years with recent evidence that defects in the expression or activity of this immediate-early gene may also contribute to the pathophysiology of brain disorders including schizophrenia and fragile X syndrome. These results bring forward the concept that reversing Arc abnormalities could provide an avenue to improve cognitive or neurological impairments in different disease contexts, but how to achieve this therapeutic objective has remained elusive. Here, we present results from a chemogenomic screen that probed a mechanistically diverse library of small molecules for modulators of BDNF-induced Arc expression in primary cortical neurons. This effort identified compounds with a range of influences on Arc, including promoting its acetylation-a previously uncharacterized post-translational modification of this protein. Together, our data provide insights into the control of Arc that could be targeted to harness neuroplasticity for clinical applications.

A brain proteomic investigation of rapamycin effects in the Tsc1+/- mouse model

BACKGROUND

Tuberous sclerosis complex (TSC) is a rare monogenic disorder characterized by benign tumors in multiple organs as well as a high prevalence of epilepsy, intellectual disability and autism. TSC is caused by inactivating mutations in the TSC1 or TSC2 genes. Heterozygocity induces hyperactivation of mTOR which can be inhibited by mTOR inhibitors, such as rapamycin, which have proven efficacy in the treatment of TSC-associated symptoms. The aim of the present study was (1) to identify molecular changes associated with social and cognitive deficits in the brain tissue of Tsc1+/- mice and (2) to investigate the molecular effects of rapamycin treatment, which has been shown to ameliorate genotype-related behavioural deficits.

METHODS

Molecular alterations in the frontal cortex and hippocampus of Tsc1+/- and control mice, with or without rapamycin treatment, were investigated. A quantitative mass spectrometry-based shotgun proteomic approach (LC-MSE) was employed as an unbiased method to detect changes in protein levels. Changes identified in the initial profiling stage were validated using selected reaction monitoring (SRM). Protein Set Enrichment Analysis was employed to identify dysregulated pathways.

RESULTS

LC-MSE analysis of Tsc1+/- mice and controls (n = 30) identified 51 proteins changed in frontal cortex and 108 in the hippocampus. Bioinformatic analysis combined with targeted proteomic validation revealed several dysregulated molecular pathways. Using targeted assays, proteomic alterations in the hippocampus validated the pathways "myelination", "dendrite," and "oxidative stress", an upregulation of ribosomal proteins and the mTOR kinase. LC-MSE analysis was also employed on Tsc1+/- and wildtype mice (n = 34) treated with rapamycin or vehicle. Rapamycin treatment exerted a stronger proteomic effect in Tsc1+/- mice with significant changes (mainly decreased expression) in 231 and 106 proteins, respectively. The cellular pathways "oxidative stress" and "apoptosis" were found to be affected in Tsc1+/- mice and the cellular compartments "myelin sheet" and "neurofilaments" were affected by rapamycin treatment. Thirty-three proteins which were altered in Tsc1+/- mice were normalized following rapamycin treatment, amongst them oxidative stress related proteins, myelin-specific and ribosomal proteins.

CONCLUSIONS

Molecular changes in the Tsc1+/- mouse brain were more prominent in the hippocampus compared to the frontal cortex. Pathways linked to myelination and oxidative stress response were prominently affected and, at least in part, normalized following rapamycin treatment. The results could aid in the identification of novel drug targets for the treatment of cognitive, social and psychiatric symptoms in autism spectrum disorders. Similar pathways have also been implicated in other psychiatric and neurodegenerative disorders and could imply similar disease processes. Thus, the potential efficacy of mTOR inhibitors warrants further investigation not only for autism spectrum disorders but also for other neuropsychiatric and neurodegenerative diseases.

A novel methodology to evaluate the molecular validity of preclinical psychosis models compared to schizophrenia brain pathology

Rodent models of schizophrenia (SCZ) are indispensable when screening for novel treatments, but quantifying their translational relevance with the underlying human pathophysiology has proved difficult. A novel systems methodology (shown in Figure 1) was developed integrating and comparing proteomic data of anterior prefrontal cortex tissue from SCZ post-mortem brains and matched controls with data obtained from four established glutamatergic rodent models, with the aim of evaluating which of these models represent SCZ most closely. Liquid chromatography coupled tandem mass spectrometry (LC-MSE) proteomic profiling was applied comparing healthy and “disease state” in human post-mortem samples and rodent brain tissue samples. Protein-protein interaction networks were constructed from significant abundance changes and enrichment analyses enabled the identification of pathophysiological characteristics of the disorder, which were represented across all four rodent models. Subsequently, these functional domains were used for cross-species comparisons. Five functional domains such as “development and differentiation” represented across all four rodent models, were identified. It was quantified that the chronic phencyclidine (cPCP) model represented SCZ brain changes most closely for four of these functional domains, by using machine-learning techniques. This is the first study aiming to quantify which rodent model recapitulates the neuropathological features of SCZ most closely. The methodology and findings presented here support recent efforts to overcome translational hurdles of preclinical psychiatric research by associating behavioural endophenotypes with distinct biological processes.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Proteomic systems evaluation of the molecular validity of preclinical psychosis models compared to schizophrenia brain pathology

Pharmacological and genetic rodent models of schizophrenia play an important role in the drug discovery pipeline, but quantifying the molecular similarity of such models with the underlying human pathophysiology has proved difficult. We developed a novel systems biology methodology for the direct comparison of anterior prefrontal cortex tissue from four established glutamatergic rodent models and schizophrenia patients, enabling the evaluation of which model displays the greatest similarity to schizophrenia across different pathophysiological characteristics of the disease. Liquid chromatography coupled tandem mass spectrometry (LC-MS^E) proteomic profiling was applied comparing healthy and "disease state" in human post-mortem samples and rodent brain tissue samples derived from models based on acute and chronic phencyclidine (PCP) treatment, ketamine treatment or NMDA receptor knockdown. Protein-protein interaction networks were constructed from significant abundance changes and enrichment analyses enabled the identification of five functional domains of the disease such as "development and differentiation", which were represented across all four rodent models and were thus subsequently used for cross-species comparison. Kernel-based machine learning techniques quantified that the chronic PCP model represented schizophrenia brain changes most closely for four of these functional domains. This is the first study aiming to quantify which rodent model recapitulates the neuropathological features of schizophrenia most closely, providing an indication of face validity as well as potential guidance in the refinement of construct and predictive validity. The methodology and findings presented here support recent efforts to overcome translational hurdles of preclinical psychiatric research by associating functional dimensions of behaviour with distinct biological processes.

Effects of olanzapine on serum protein phosphorylation patterns in patients with schizophrenia

PURPOSE

Previous studies have shown that blood serum phosphoproteins are altered in schizophrenia patients in comparison to controls. However, it is not known whether phosphoproteins are also changed in response to treatment with antipsychotics.

EXPERIMENTAL DESIGN

Blood samples were taken from patients (n = 23) at baseline and after 6 weeks of olanzapine treatment. Immobilized metal ion affinity chromatography (IMAC) was used for enrichment of serum phosphoproteins and these were analyzed by label-free LC-MS in expression mode (LC-MS(E) ).

RESULTS

We identified 11 proteins that were changed significantly in overall abundance and 45 proteins that showed changes in phosphorylation after the antipsychotic treatment. The altered phosphoproteins were mainly involved in the acute phase response, lipid and glucose homeostasis (LXR), retinoic acid signaling (RXR), and complement pathways. Some of the proteins showed a marked increase in phosphorylation, including apolipoprotein A-I (3.4-fold), alpha-1-anti-chymotrypsin (3.1-fold), and apolipoprotein B-100 (2.2-fold). In addition, several proteins showed either decreased phosphorylation (e.g. complement C4A, collagen alpha-1 chain, complement factor H) or a mixture of increased and decreased phoshphorylation (e.g. afamin, complement C5, complement factor B). Finally, 24 of the altered phosphoproteins showed opposite directional changes in a comparison of baseline schizophrenia patients before and after treatment with olanzapine. These included alpha-1B-glycoprotein, apolipoprotein A-IV, vitamin D-binding protein, and prothrombin.

CONCLUSIONS AND CLINICAL RELEVANCE

These data demonstrate the potential for future studies of serum phosphoproteins as a readout of physiological function and might have utility in studies aimed at identification of biomarkers for drug response prediction or monitoring.

Hippocampal Proteomic and Metabonomic Abnormalities in Neurotransmission, Oxidative Stress, and Apoptotic Pathways in a Chronic Phencyclidine Rat Model

Schizophrenia is a neuropsychiatric disorder affecting 1% of the world's population. Due to both a broad range of symptoms and disease heterogeneity, current therapeutic approaches to treat schizophrenia fail to address all symptomatic manifestations of the disease. Therefore, disease models that reproduce core pathological features of schizophrenia are needed for the elucidation of pathological disease mechanisms. Here, we employ a comprehensive global label-free liquid chromatography-mass spectrometry proteomic (LC-MS(E)) and metabonomic (LC-MS) profiling analysis combined with the targeted proteomics (selected reaction monitoring and multiplex immunoassay) of serum and brain tissues to investigate a chronic phencyclidine (PCP) rat model in which glutamatergic hypofunction is induced through noncompetitive NMDAR-receptor antagonism. Using a multiplex immunoassay, we identified alterations in the levels of several cytokines (IL-5, IL-2, and IL-1β) and fibroblast growth factor-2. Extensive proteomic and metabonomic brain tissue profiling revealed a more prominent effect of chronic PCP treatment on both the hippocampal proteome and metabonome compared to the effect on the frontal cortex. Bioinformatic pathway analysis confirmed prominent abnormalities in NMDA-receptor-associated pathways in both brain regions, as well as alterations in other neurotransmitter systems such as kainate, AMPA, and GABAergic signaling in the hippocampus and in proteins associated with neurodegeneration. We further identified abundance changes in the level of the superoxide dismutase enzyme (SODC) in both the frontal cortex and hippocampus, which indicates alterations in oxidative stress and substantiates the apoptotic pathway alterations. The present study could lead to an increased understanding of how perturbed glutamate receptor signaling affects other relevant biological pathways in schizophrenia and, therefore, support drug discovery efforts for the improved treatment of patients suffering from this debilitating psychiatric disorder.

Targeted multiplexed selected reaction monitoring analysis evaluates protein expression changes of molecular risk factors for major psychiatric disorders

BACKGROUND

Extensive research efforts have generated genomic, transcriptomic, proteomic, and functional data hoping to elucidate psychiatric pathophysiology. Selected reaction monitoring, a recently developed targeted proteomic mass spectrometric approach, has made it possible to evaluate previous findings and hypotheses with high sensitivity, reproducibility, and quantitative accuracy.

METHODS

Here, we have developed a labelled multiplexed selected reaction monitoring assay, comprising 56 proteins previously implicated in the aetiology of major psychiatric disorders, including cell type markers or targets and effectors of known psychopharmacological interventions. We analyzed postmortem anterior prefrontal cortex (Brodmann area 10) tissue of patients diagnosed with schizophrenia (n=22), bipolar disorder (n=23), and major depressive disorder with (n=11) and without (n=11) psychotic features compared with healthy controls (n=22).

RESULTS

Results agreed with several previous studies, with the finding of alterations of Wnt-signalling and glutamate receptor abundance predominately in bipolar disorder and abnormalities in energy metabolism across the neuropsychiatric disease spectrum. Calcium signalling was predominantly affected in schizophrenia and affective psychosis. Interestingly, we were able to show a decrease of all 4 tested oligodendrocyte specific proteins (MOG, MBP, MYPR, CNPase) in bipolar disorder and to a lesser extent in schizophrenia and affective psychosis. Finally, we provide new evidence linking ankyrin 3 specifically to affective psychosis and the 22q11.2 deletion syndrome-associated protein septin 5 to schizophrenia.

CONCLUSIONS

Our study highlights the potential of selected reaction monitoring to evaluate the protein abundance levels of candidate markers of neuropsychiatric spectrum disorders, providing a high throughput multiplex platform for validation of putative disease markers and drug targets.

Proteomic enrichment analysis of psychotic and affective disorders reveals common signatures in presynaptic glutamatergic signaling and energy metabolism

BACKGROUND

Although genetic studies suggest an overlap in risk alleles across the major psychiatric disorders, disease signatures reflecting overlapping symptoms have not been found. Profiling studies have identified candidate protein markers associated with specific disorders of the psychoaffective spectrum, but this has always been done in a selective fashion without accounting for the entire proteome composition of the system under investigation.

METHODS

Employing an orthogonal system-based proteomic enrichment approach based on label-free liquid chromatography mass spectrometry, we analyzed anterior prefrontal human post-mortem brain tissue of patients affected by schizophrenia (n = 23), bipolar disorder (n = 23), major depressive disorder with (n = 12) and without psychotic features (n = 11), and healthy controls (n = 23). Labeled selected reaction monitoring (SRM) was used to validate these findings on a pathway level. Independent in silico analyses of biological annotations revealed common pathways across the diseases, associated with presynaptic glutamatergic neurotransmission and energy metabolism. We validated the proteomic findings using SRM and confirmed that there were no effects of post-mortem confounders.

RESULTS

Schizophrenia and affective psychosis were linked to a hypoglutamatergic state and hypofunction of energy metabolism, while bipolar disorder and major depressive disorder were linked to a hyperglutamatergic state and hyperfunction of energy metabolism.

CONCLUSIONS

These findings support recent investigations, which have focused on the therapeutic potential of glutamatergic modulation in psychotic and affective disorders. We suggest a disease model in which disturbances of the glutamatergic system and ensuing adaptations of neuronal energy metabolism are linked to distinct psychiatric symptom dimensions, delivering novel evidence for targeted treatment approaches.

Integrative proteomic analysis of the NMDA NR1 knockdown mouse model reveals effects on central and peripheral pathways associated with schizophrenia and autism spectrum disorders

Background

Over the last decade, the transgenic N-methyl-D-aspartate receptor (NMDAR) NR1-knockdown mouse (NR1^neo−/−) has been investigated as a glutamate hypofunction model for schizophrenia. Recent research has now revealed that the model also recapitulates cognitive and negative symptoms in the continuum of other psychiatric diseases, particularly autism spectrum disorders (ASD). As previous studies have mostly focussed on behavioural readouts, a molecular characterisation of this model will help to identify novel biomarkers or potential drug targets.

Methods

Here, we have used multiplex immunoassay analyses to investigate peripheral analyte alterations in serum of NR1^neo−/− mice, as well as a combination of shotgun label-free liquid chromatography mass spectrometry, bioinformatic pathway analyses, and a shotgun-based 40-plex selected reaction monitoring (SRM) assay to investigate altered molecular pathways in the frontal cortex and hippocampus. All findings were cross compared to identify translatable findings between the brain and periphery.

Results

Multiplex immunoassay profiling led to identification of 29 analytes that were significantly altered in sera of NR1^neo−/− mice. The highest magnitude changes were found for neurotrophic factors (VEGFA, EGF, IGF-1), apolipoprotein A1, and fibrinogen. We also found decreased levels of several chemokines. Following this, LC-MS^E profiling led to identification of 48 significantly changed proteins in the frontal cortex and 41 in the hippocampus. In particular, MARCS, the mitochondrial pyruvate kinase, and CamKII-alpha were affected. Based on the combination of protein set enrichment and bioinformatic pathway analysis, we designed orthogonal SRM-assays which validated the abnormalities of proteins involved in synaptic long-term potentiation, myelination, and the ERK-signalling pathway in both brain regions. In contrast, increased levels of proteins involved in neurotransmitter metabolism and release were found only in the frontal cortex and abnormalities of proteins involved in the purinergic system were found exclusively in the hippocampus.

Conclusions

Taken together, this multi-platform profiling study has identified peripheral changes which are potentially linked to central alterations in synaptic plasticity and neuronal function associated with NMDAR-NR1 hypofunction. Therefore, the reported proteomic changes may be useful as translational biomarkers in human and rodent model drug discovery efforts.

Ovulation-inducing drugs: a drug utilization and risk study in the Dutch population

This study describes the use of the ovulation stimulating drugs clomifene, human chorionic gonadotropin (hCG) and human menopausal gonadotropin (hMG) in a representative sample of a population of Dutch women in the child-bearing age group. Clomifene or hMG/hCG are seldom used alone. A considerable percentage of the women received at least four different ovulation-inducing and related drugs during the observation period of two years. Thirty percent of the women who used clomifene were treated for 6 or more cycles. These findings argue for a relative "overuse" and "misuse" of clomifene. Buserelin, a drug not registered for the indication ovulation induction in The Netherlands but used in in vitro fertilization (IVF) programs as inhibitors of pituitary gonadotropin production, was nevertheless prescribed to 38% of the hMG /hCG users and to 11 % of the clomifene users. Our study indicates that, though the potential risks of congenital malformations due to clomifene are difficult to assess, they may be considerable; this, and the fact that different ovulation-inducing drugs are used together with clomifene, emphasizes the need for post-marketing surveillance.

Behavioral and molecular biomarkers in translational animal models for neuropsychiatric disorders

Modeling neuropsychiatric disorders in animals poses a significant challenge due to the subjective nature of diverse often overlapping symptoms, lack of objective biomarkers and diagnostics, and the rudimentary understanding of the pathophysiology. Successful translational research requires animal models that can inform about disease mechanisms and therapeutic targets. Here, we review behavioral and neurobiological findings from selected animal models, based on presumed etiology and risk factors, for schizophrenia, bipolar disorder, and major depressive disorder. We focus on the use of appropriate statistical tools and newly developed Research Domain Criteria (RDoC) to link biomarkers from animal models with the human disease. We argue that this approach will lead to development of only the most robust animal models for specific psychiatric disorders and may ultimately lead to better understanding of the pathophysiology and identification of novel biomarkers and therapeutic targets.

[Lowering of diastolic blood pressure < or = 90 mmHg should not be attempted, except in type 2 diabetics; the 'Hypertension optimal treatment' (HOT) trial]

Recently the 'Hypertension optimal treatment' (HOT) study was reported. In this study 18,790 patients with diastolic blood pressure between 100 and 115 mmHg were randomly assigned target pressures of < or = 90, < or = 85 and < or = 80 mmHg respectively, and treated with a felodipine-based antihypertensive regimen. In all three groups an impressive fall in both diastolic and systolic blood pressures, and as a consequence very few major cardiovascular events (the primary endpoint of the study) were observed, but there was no difference in endpoint scores among the three groups. Type 2 diabetic patients fared substantially better than non-diabetic patients and they are likely to profit if their diastolic pressure is decreased below 80 mmHg. In the remaining patients rigorous maintenance of present-day standards (diastolic pressure < or = 90 mmHg) is advised. The addition of 75 mg aspirin 1 dd resulted in a modest but significant reduction of major cardiovascular events, but at the cost of increased gastrointestinal bleedings.

Clinical and neurohumoral differences between spirapril and captopril in mild to moderate chronic congestive heart failure

BACKGROUND

This study was done to determine whether the difference in duration of action of the long-acting angiotensin-converting enzyme (ACE) inhibitor spirapril compared with the short-acting ACE inhibitor captopril affects clinical efficacy in patients with congestive heart failure.

METHODS AND RESULTS

The effects on exercise capacity, neurohumoral status, and quality of life were studied in 20 patients with mild to moderate congestive heart failure in a double-blind, randomized, comparative study in parallel groups with a duration of 12 weeks. All assessments during the study were performed in the morning, before intake of the study medication, to avoid the expected peak effect of the ACE inhibitors used. Mean peak oxygen consumption (peak Vo2) was 17.4 mL/min/kg (range, 14.2-19.9 mL/min/kg) and mean left ventricular ejection fraction was 28% (range, 13-40%). Exercise duration in the captopril group showed a significant increase after 12 weeks (P < .05) of treatment compared with the spirapril group. Peak oxygen consumption tended only to increase in the captopril-treated patients compared with the spirapril-treated patients. Serum ACE activity was significantly different between the two treatment groups during treatment (P < .0001) and showed only a significant decrease in the spirapril group. There was no difference in improvement of quality of life between the two treatment groups.

CONCLUSIONS

This study showed that the effects of the ACE inhibitors spirapril and captopril on exercise capacity are not related to the degree of inhibition of serum ACE activity.

Rate-dependent effects of the class III antiarrhythmic drug almokalant on refractoriness in the pig

The electrophysiologic effects of intravenously administered almokalant, a new class III antiarrhythmic drug, in 7 isoflurane-anesthetized pigs after low and high dose were investigated. Low-dose almokalant included bolus infusion of 0.05 mumol/kg/min for 5 min followed by a continuous infusion of 0.0025 mumol/kg/min for 40 min. Thereafter, a high dose of 0.2 mumol/kg/min for 5 min and 0.01 mumol/kg/min for 40 min was given. PR, QRS, AH, and HV intervals did not change during almokalant administration. The QT interval increased dose dependently from 337 +/- 17 to 442 +/- 20 ms at high dose (p < 0.05). Atrial refractory periods (AERP) were prolonged dose dependently at a 500-ms pacing cycle length from 178 +/- 15 at baseline to 227 +/- 27 and 253 +/- 23 ms during low- and high-dose almokalant infusion, respectively. For pacing cycle lengths of 400 and 300 ms, these values were 180 +/- 11, 207 +/- 25, and 259 +/- 34 and 157 +/- 12, 193 +/- 21, and 234 +/- 28 ms, respectively. At a pacing cycle length of 500 ms, mean ventricular effective refractory period (VERP) was 270 +/- 25 ms as compared with 306 +/- 24 and 337 +/- 17 during low and high dose, respectively. A similar pattern of VERP changes during both low- and high-dose infusion was noted at the shorter pacing cycle lengths, with an increase from 240 +/- 23 to 274 +/- 22 and 279 +/- 24 ms during a 400-ms cycle length and from 210 +/- 17 to 235 +/- 19 and 234 +/- 21 ms during a 300-ms cycle length. The ratio of the VERP and ventricular monophasic action potential duration (VAPD) did not change significantly. The Wenckebach cycle length increased by 36 +/- 36 and 83 +/- 37 ms with low- and high-dose almokalant infusion, respectively. The percent increase of AERP at pacing cycle lengths of 500, 400, and 300 ms during high-dose almokalant was 42, 44, and 49%, respectively; these increases for VERP were 25, 16, and 11%, respectively. In conclusion, prolongation of refractoriness by almokalant was more pronounced at the atrial than the ventricular level. Prolongation of refractoriness was maintained at short pacing cycle lengths especially in the atrium, indicating absence of reverse-use dependence of almokalant in the porcine heart. The marked atrial effects, paralleled by atrioventricular conduction slowing, and the absence of reverse use-dependence all contribute to the feasibility of use of almokalant, in particular in the treatment of supraventricular tachyarrhythmias.

Comparative effects of diltiazem and lisinopril on left ventricular structure and filling in mild-to-moderate hypertension

The comparative effects on echocardiographically determined left ventricular (LV) mass and pulsed Doppler derived indexes of LV diastolic filling were studied in previously untreated hypertensive patients after 6 months of treatment with diltiazem 300 mg once daily (o.d.) (n = 16), and lisinopril 20 mg o.d. (n = 20). LV mass index decreased in the lisinopril group (from 98 to 96 g/m2; mean difference after 6 months of treatment with diltiazem-lisinopril was 13.7 g/m2 [95% confidence interval (CI) 0.8 to 26.6, p < 0.05]. In both groups diastolic filling parameters improved, but there was no statistically significant difference between the groups. Both treatment regimens showed a similar decrease in office and maximal exercise systolic blood pressure (SPB). Ambulatory daytime BP was lower after lisinopril treatment (from 147/96 to 126/83 mm Hg) than after diltiazem treatment (from 142/93 to 135/87 mm Hg); mean difference between diltiazem and lisinopril after 6 months of treatment was 9.7 (95% CI 3.4 to 16.0, p < 0.05)/9.4 (95% CI 2.5 to 16.3, p < 0.05) mm Hg. Nighttime BP decreased from 129/81 to 113/70 mm Hg in the lisinopril group, but not in the diltiazem group (from 125/79 to 122/77 mm Hg); mean difference between diltiazem and lisinopril after 6 months of treatment was 4.4 (95% CI - 0.2 to 8.9)/6.6 (95% CI 1.1 to 12.0) mm Hg. Changes in diastolic filling parameters were significantly correlated with changes in LV mass index in the lisinopril group, suggesting that the improvements in diastolic filling in the diltazem group may be partly due to an effect on factors other than LV mass.

Relationship of changes in felodipine pharmacokinetics to haemodynamics during chronic oral treatment of congestive heart failure patients

In congestive heart failure patients the kinetics of felodipine, a dihydropyridine calcium antagonist, show interpatient differences after acute i.v. administration that disappear after 8 weeks oral treatment with a change in kinetics in the patients with the largest clearances (CL) and the smallest volumes of distribution (Vss). Pharmacokinetic and haemodynamic data were combined to construct a haemodynamic-pharmacokinetic model. This model shows that the differences between the patients in i.v. pharmacokinetics are consistent with a difference in plasma flow distribution between liver and poorly perfused tissues. In patients in whom kinetics changed, felodipine treatment is supposed to cause a redistribution of flow from liver to peripheral tissues, accompanied by a decreased work load of the heart and a larger increase in VO2max during therapy than in the other patients, whose workload increased. This suggests a better therapeutic response in the patients whose kinetics changed. As change in kinetics is related to felodipine CL and CL to liver plasma flow, felodipine CL or even indocyanine CL might be predictive for the therapeutic effect of felodipine.

Relation between myocardial beta-adrenoceptor density and hemodynamic and neurohumoral changes in a rat model of chronic myocardial infarction: effects of ibopamine and captopril

OBJECTIVES

The purpose of this study was to investigate the changes in beta-adrenoceptor density (Bmax) and distribution in a model of chronic myocardial infarction in rats, and to relate possible changes to hemodynamic and neurohumoral abnormalities. In addition, we examined the effects of 8 weeks treatment with ibopamine and captopril.

METHODS

There were 3 experiments: (1) Bmax and plasma catecholamines were examined (n = 46), (2) Bmax was compared in infarcted and non-infarcted tissue (n = 13), and (3) contractile function was evaluated by isolated heart perfusion (n = 40). Of rats in Expts. (1) and (3), 50% had myocardial infarction induced by coronary ligation and 50% were controls. Each group was divided between ibopamine, ibopamine and captopril, or standard (no drug) treatment.

RESULTS

Bmax was not decreased in rats with myocardial infarction (10.8 +/- 0.8 fmol/mg protein), compared to normal rats (11.4 +/- 0.6 fmol/mg protein), and the ratio beta 1/beta 2 was also unaffected. In infarcted tissue, Bmax was significantly (P = 0.03) lower than in non-infarcted tissue. Baseline left ventricular pressure, systolic and diastolic dP/dT were all impaired (P < 0.001), and plasma norepinephrine levels were elevated in rats with myocardial infarction (16.03 +/- 230 vs. 1287 +/- 83 pg/ml; P < 0.05), compared to normals. Both ibopamine alone and in combination with captopril reduced the elevated plasma norepinephrine levels in infarcted rats (P < 0.001), but only the combination of the 2 drugs significantly increased Bmax in infarcted rats (14.7 +/- 0.8 fmol/mg protein; P = 0.03 vs. untreated myocardial infarction), while ibopamine alone had no significant effect (13.1 +/- 1.1 fmol/mg protein; p = ns). Also, active drug treatment had no significant effect on the hemodynamic changes.

CONCLUSIONS

In this coronary artery ligation model of myocardial infarction in rats, no beta-adrenoceptor down-regulation is observed, despite marked abnormalities in baseline left ventricular function and plasma norepinephrine levels. The combination of ibopamine and captopril significantly increases Bmax in infarcted rats, which is accompanied by a reduction in plasma norepinephrine levels, but not by an improvement in hemodynamic parameters.

Vulvo-vaginal candidiasis associated with acitretin

The aim of this study was to estimate the risk of vulvo-vaginal candidiasis among the users of acitretin. The incidence rate ratio of vulvo-vaginal candidiasis was estimated in a cohort of acitretin users by using prescription sequence analysis. Study subjects were 196 women between 15 and 45 years of age, exposed to acitretin in 1990. Prescriptions of drugs for treatment of vulvo-vaginal candidiasis were used as proxy for the occurrence of vulvo-vaginal candidiasis. Validation of the proxy drug was performed by record linkage of pharmacy and medical records. In addition to the risk estimation by incidence rate ratios a case-crossover study with patient-stratified logistic regression analysis was performed to control for distortion due to individual differences in contribution of exposure time. The positive predictive value of the proxy drug for vulvo-vaginal candidiasis ranged between 57 and 100%, the sensitivity was 87% and the specificity estimated 99%. The crude incidence rate ratio for vulvo-vaginal candidiasis following acitretin exposure was 2.8 (CI95%: 1.1-7.1). The pooled Mantel-Haenszel incidence rate ratio was 3.3 (CI95%: 1.1-9.6) after stratification for accumulated level of exposure. Patient-stratified analysis on the subgroup of cases (n = 15) revealed an odds ratio of 6.5 (CI95%: 2.3-18.2). This study strongly suggests that the higher occurrence of vulvo-vaginal candidiasis during acitretin exposure is attributable to the drug.

The role of pharmacists in the recruitment of a cohort for postmarketing surveillance. A case study of acitretin in The Netherlands

In October 1990, a recall procedure was issued regarding the drug acitretin. The recommended post-therapy contraception period after acitretin therapy was extended from 2 months to 2 years. For a postmarketing surveillance study, we recruited a cohort from the source population of women aged 15-45 years who were exposed to acitretin. Recruitment occurred through dermatologists, and pharmacists plus dispensing general practitioners. We describe the speed of and the response to the recruitment procedures, and the representativeness of the recruited cohort. We also studied whether the individuals who gave informed consent would have preferred to be recruited by either dermatologists or pharmacists, and whether the information obtained from pharmacists and dispensing general practitioners was valid. This study revealed that pharmacists and dispensing general practitioners (drug dispensers) recruited their subjects rapidly, with no or little selection; they attained a 42% response. Dermatologists recruited their subjects slowly and selectively; they attained a 24% response. The majority of women (60%) recruited by dermatologists would have given their informed consent if they would have been recruited by their pharmacists. Drug dispensers are essential contributors to the recruitment of a study population. We do advise that such recruitment for a postmarketing surveillance study occurs by means of a collaboration between pharmacists and physicians.

Effects of spirapril and captopril on regional blood flow in chronic congestive heart failure: a comparison between a short- and a long-acting angiotensin-converting enzyme inhibitor

Spirapril is a new angiotensin-converting enzyme (ACE) inhibitor with a long duration of action. To determine whether duration of inhibition of serum ACE activity may affect regional blood flow (RBF), we compared spirapril with captopril, an ACE inhibitor with a short duration of action. Both the short- and long-term effects were studied in patients with mild to moderate congestive heart failure (CHF). Calf, renal, and hepatic BF measurements were performed in the morning before intake of the study medication; 24 h after the previous dose of spirapril (n = 9 patients) and 12 h after the previous dose of captopril (n = 9 patients). Serum ACE activity after 1, 6, and 12 weeks was significantly reduced in patients receiving spirapril, but not in those receiving captopril. The decrease in mean arterial pressure (MAP) was more pronounced in the spirapril group. Calf BF showed a slight but not significant increase in both spirapril- and captopril-treated patients. Effective renal BF increased significantly only in patients treated with spirapril. Although filtration fraction (FF) tended to decrease in the spirapril group, the decrease was significant only in the captopril group. No changes were observed in hepatic BF. Cerebral BF (CBF) measurements were performed after intake of the first dose of study medication and after 12 weeks, immediately after drug intake. Significant reduction in MAP in the two treatment groups both after the first dose and after 12 weeks did not affect CBF. Despite a significantly prolonged decrease in MAP and serum ACE activity in spirapril-treated patients, no marked differences in RBF were noted between the two ACE inhibitors.

Communicating a drug alert. A case study on acitretin in The Netherlands

In October 1990, a recall procedure was initiated for the teratogenic drug acitretin, and the recommended post-therapy contraception period after acitretin therapy was extended from 2 months to 2 years due to the possibility of its conversion to the lipophilic compound etretinate. The aim of the present study was to evaluate the communication procedures and their effects as a drug alert from the health authorities, the pharmaceutical company and professional associations of health professionals to the population at risk. A model was used to evaluate communication between three hierarchical levels. Data were obtained via semi-structured interviews and structured questionnaires. Communication procedures were evaluated according to channel characteristics and by analysis of their contents. The effect was measured as whether the drug dispensers identified acitretin users, contacted physicians, and whether physicians communicated in person with the population at risk. The penetration of direct mail from the health authorities and from the pharmaceutical company ranged from 97-98% and 65-94% at Level 2 (health professionals). The population at risk was informed via personal communication with health professionals, and/or the mass media. Of the women at risk, 19% were contacted by a dermatologist, 30% by their GP, and 39% by the pharmacist. 35% was never informed by any health professional. The Dutch health care system is adequately equipped for effective communication between health authorities, pharmaceutical industry and health professionals.(ABSTRACT TRUNCATED AT 250 WORDS)

Late potentials, QTc prolongation, and prediction of arrhythmic events after myocardial infarction

In a series of 171 consecutive survivors of acute myocardial infarction, the predictive value of late potentials and QTc prolongation was prospectively assessed. QT intervals were measured in lead V2, corrected QT (QTc) was calculated using Bazett's equation (cut-off value 440 ms). Late potentials were considered to be present when all of the three signal-averaged electrocardiographic variables were abnormal (i.e. QRS > 114 ms, D40 > 38 ms, and V40 < 20 microV). Complete follow-up was obtained (mean 13 +/- 6 months, range 6-24 months). Six percent of the patients had an arrhythmic event (i.e. sustained ventricular tachycardia or sudden death). The relative risk of late potentials for arrhythmic events was 7.7 (P < 0.02). The relative risk of QTc > 440 ms was 1.1 (NS). In a multivariate analysis, the addition of QTc prolongation did not significantly improve the prognostic value of late potentials alone. It is concluded that late potentials are predictive of arrhythmic events after myocardial infarction, but the presence of concomitant QTc prolongation does not worsen the prognosis.

Inability to detect plasma etretinate and acitretin is a poor predictor of the absence of these teratogens in tissue after stopping acitretin treatment

1. Concentrations of etretinate, acitretin and its main metabolite 13-cis-acitretin were measured in plasma and subcutaneous fat samples from 37 women of childbearing age exposed to acitretin before November 1990. Twenty of the women still used acitretin and 17 had stopped therapy for a period ranging from 1 to 29 months. 2. The prevalences of detectable etretinate concentrations were 45% and 83% in plasma and subcutaneous tissue, respectively, among current acitretin users and 18% and 86% among those who had stopped acitretin therapy. Thus, inability to detect plasma etretinate is a poor predictor of the absence of etretinate in fat. 3. Acitretin and/or etretinate were detectable in fat and in some cases in plasma from women who had ceased acitretin therapy for up to 29 months. 4. We suggest that (cis)-acitretin and etretinate should be monitored in subcutaneous tissue when plasma measurements are negative. The recommended contraception period of 2 years after cessation of acitretin therapy should be reconsidered to avoid the risk of teratogenicity.

Effect of metoprolol on atrial fibrillatory rate, atrioventricular nodal concealed conduction, and ventricular response during atrial fibrillation in pigs

We wished to elucidate the effect of beta-blockade on fibrillatory rate and atrioventricular (AV) nodal concealed conduction during atrial fibrillation (AF). Subsequent to determination of the effect on atrial functional refractoriness with the extrastimulus technique (basic cycle length 400 ms), the effect of metoprolol (0.3 mg/kg) on atrial fibrillatory rate was determined in 8 open-chest pigs with metacholine-facilitated AF. Once stable AF was established, fibrillatory rate was recorded with a bipolar epicardial electrode, together with the ventricular response during 500 ventricular intervals. For each episode of AF, three indexes were calculated to determine the degree of concealed conduction: the ratio of the longest to the shortest ventricular interval, the ratio of the median ventricular interval to the median atrial interval, and the coefficient of variation of the ventricular intervals. Metoprolol decreased fibrillatory rate (571-432 beats/min, p < 0.01), suggesting a proportionate increase (+32%) in atrial functional refractoriness during AF that far exceeded the increase (+7%) during sinus rhythm (217-233 ms, p < 0.05). None of the indexes of concealed conduction was affected by metoprolol. Metoprolol decreases fibrillatory rate in AF, possibly due in part to its class I effect, causing rate-dependent prolongation of atrial refractoriness. Despite reducing fibrillatory rate, metoprolol does not affect AV nodal concealed conduction measurably. Our results support the assumption that the reducing effect of beta-blockers on ventricular rate during AF is due to direct prolongation of AV nodal refractoriness.

Neurohumoral and hemodynamic effects of ibopamine in a rat model of chronic myocardial infarction and heart failure

There is increasing evidence that both neurohumoral and hemodynamic factors play a role in disease progression in chronic heart failure (CHF). To examine the influence of the oral dopamine agonist ibopamine on these factors, we studied 20 rats with chronic myocardial infarction and CHF, and compared them with 20 normal rats. After 6 weeks, rats were randomly divided between control treatment (50%) or ibopamine (50%) for 3 weeks. At the end of the study, plasma and tissue neurohumoral parameters, as well as hemodynamics, were determined. In infarcted rats, the elevated plasma norepinephrine (PNE) levels were reduced by ibopamine (251 +/- 19 vs. 138 +/- 32 pg/ml; p < 0.05). Other plasma neurohormones measured (epinephrine, renin, aldosterone, and angiotensin converting enzyme [ACE]) were not significantly increased in rats with myocardial infarction and were not affected by ibopamine. Cardiac (tissue) ACE was increased in infarcted rats (12.1 +/- 1.9 U/l/min) and was significantly lowered by ibopamine (9.6 +/- 1.0 U/l/min; p < 0.05); renal ACE was unaffected. Blood pressure and heart rate were similar in the two groups and were not influenced by ibopamine treatment. In conclusion, in chronic myocardial infarction and CHF in rats, ibopamine reduces the elevated levels of PNE and cardiac ACE. Further research will be needed to determine whether this effect may lead to a favorable influence on disease progression in CHF.

Effects of acetylsalicylic acid on peripheral hemodynamics in patients with chronic heart failure treated with angiotensin-converting enzyme inhibitors

Cyclooxygenase inhibitors may affect the hemodynamic status of patients with heart failure adversely and may also block the vasodilatory effects of angiotensin-converting enzyme (ACE) inhibitors in such patients. Relatively low doses of the cyclooxygenase inhibitor acetylsalicylic acid (ASA) are now used routinely in ischemic heart disease, the most important cause of heart failure. Therefore, we investigated the hemodynamic interaction between ASA and captopril in heart failure. In a randomized, cross-over study, 13 patients with congestive heart failure (CHF) who were already receiving maintenance treatment with an ACE inhibitor received a single dose of 25 mg captopril combined with 236 mg ASA or placebo. Peripheral blood flow was studied noninvasively by venous occlusion plethysmography of the calves. Liver blood flow was estimated from indocyanine green (ICG) clearance. Administration of captopril alone significantly decreased blood pressure (BP), and ICG clearance. Calf blood flow remained unchanged. However, after arterial occlusion, hyperemic calf blood flow persisted for longer. Captopril alone did not significantly change the plasma levels of the vasodilating prostaglandins PGI2 and PGE2 or the vasoconstricting thromboxane A2 (TXA2). In contrast, captopril combined with ASA reduced the plasma levels of these vasoactive substances, with significant decreases in PGE2 and TXA2 as compared with captopril alone, yet the hemodynamic alterations after captopril plus ASA were similar to those observed after captopril alone. A single antithrombotic dose of ASA (236 mg) in 13 patients with CHF [New York Heart Association (NYHA) class II-IV] undergoing chronic treatment with ACE inhibitors had no discernible effect on hemodynamic status.(ABSTRACT TRUNCATED AT 250 WORDS)

Endothelium dependent relaxation in two different models of chronic heart failure and the effect of ibopamine

OBJECTIVES

The purpose was to relate endothelium dependent relaxation to neurohumoral and haemodynamic changes in rats with chronic heart failure.

METHODS

Rats were submitted to either coronary ligation causing myocardial infarction or banding of the abdominal aorta (aortic stenosis), and comparisons were made with normal rats (n = 20 per group). Starting six weeks after surgery, half of the experimental animals received ibopamine and the other half served as controls and were given saline for another three weeks. After this, haemodynamic and neurohumoral variables were determined and the rats were killed. Rings of both the thoracic and abdominal aorta were studied in organ baths to measure their response to vasoactive agents.

RESULTS

Increased plasma noradrenaline concentrations in rats with myocardial infarction and aortic stenosis were reduced by ibopamine. Blood pressure and heart rate, which were higher in rats with aortic stenosis than in rats with myocardial infarction and in normal rats, were unaffected by ibopamine. The maximal relaxation to sodium nitrite was depressed in the thoracic aorta from rats with myocardial infarction. The pIC50 of metacholine induced relaxation was smaller in the thoracic aorta from rats with myocardial infarction and aortic stenosis. By contrast, both pIC50 and the maximal relaxation (Emax) were increased in the abdominal aorta from rats with aortic stenosis, whereas Emax was smaller in rats with myocardial infarction. Ibopamine had no significant effects on these responses.

CONCLUSIONS

Endothelium dependent relaxation to metacholine was selectively altered in rats with chronic heart failure due to aortic stenosis, probably because of differences in regional haemodynamics. In rats with myocardial infarction, however, endothelium dependent relaxation was impaired in both the thoracic and abdominal aorta. Ibopamine acted as a neurohumoral modulator by reducing increased noradrenaline concentrations but had no significant effect on either endothelium dependent or independent relaxation.

Selective and time related activation of the cardiac renin-angiotensin system after experimental heart failure: relation to ventricular function and morphology

OBJECTIVE

The cardiac renin-angiotensin system is activated in experimental heart failure, but it is unknown at what stage of heart failure it becomes activated, and whether activation is related to ventricular dysfunction and dilatation. Changes in activity of cardiac, renal, and plasma angiotensin converting enzyme (ACE) were therefore examined at different stages of experimental heart failure, with simultaneous measurements of left ventricular pressure, systolic dP/dt, and inner ventricular radius.

METHODS

Heart failure was induced by experimental infarction in 17 normotensive male Wistar rats; 14 rats were sham operated. Rats were killed 3, 5, or 80 d after infarction. In an isolated heart perfusion, left ventricular pressure and systolic dP/dT were measured. ACE activity was determined in samples of the left and right cardiac ventricle, kidney, and plasma. Radius of the ventricular cavity was planimetrically determined in transverse sections of the left ventricle.

RESULTS

At the different stages both left ventricular pressure and systolic dP/dT progressively decreased and inner radius of the left ventricle increased in all heart failure groups. ACE activity in the left ventricle increased significantly in all heart failure groups and correlated inversely with left ventricular pressure (R = -0.81; p < 0.001) and dP/dt (R = -0.85; p < 0.001). ACE activity in the kidney was only increased 80 d after the induction of heart failure [17(SEM 1) v 11.2(0.5) nM His-Leu generated per min.mg-1, p < 0.01], while plasma ACE activity was not increased in any heart failure group.

CONCLUSIONS

Cardiac ACE is activated in the early stage after induction of heart failure and is related to the amount of dysfunction. ACE in the kidney is activated only in the chronic stage. The cardiac renin-angiotensin system therefore already appears to be an important neurohumoral adjustment in the early stage of heart failure and is thereby a suitable target for early intervention by ACE inhibitors.

Characterization of hypertensive subjects who become normotensive during three months of office BP follow-up: comparison with subjects with sustained hypertension and normotensives, and follow-up after two years

After an observation period of three months, 83% of new hypertensives (n = 84), identified in a population survey, became normotensive. Those with sustained hypertension (n = 14) were compared with 14 initially hypertensives who became normotensive and 14 normotensives, matched for age and sex, using ambulatory and exercise BP and echocardiography (both M-mode and Doppler). The initially hypertensive group (n = 11) was re-examined after two years follow-up. The 24h mean ambulatory and submaximal systolic exercise BP did not differ between sustained (139/92 and 210 mmHg) and initially hypertensives (143/95 and 217 mmHg), being significantly lower in the normotensive group (129/85 and 198 mmHg). Left ventricular mass did not differ between the initially hypertensive and the normotensive groups, being significantly higher in the sustained hypertensives. In both hypertensive groups, as compared with normotensives, the ratio between flow velocity in early and late diastole (E/A ratio) tended to be lower and the early diastolic deceleration time (DT) was significantly shorter. After two years, in the untreated initially hypertensives, office DBP had increased to hypertensive values, without change in ambulatory BP, left ventricular mass or early diastolic deceleration time. The E/A ratio had decreased to a level < 1. We conclude that the subjects who became normotensive after three months office BP follow-up have a BP load and signs of compromised left ventricular diastolic function similar to that of the sustained hypertensives, but without increased left ventricular mass.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of streptokinase during acute myocardial infarction on the signal-averaged electrocardiogram and on the frequency of late arrhythmias

Although a number of studies have shown that the incidence of late potentials is lower after thrombolytic therapy, it is not known whether this is paralleled by fewer arrhythmic events during long-term follow-up. In patients with first acute myocardial infarction, filtered QRS duration was significantly shorter when treated with streptokinase (95 +/- 11 ms, n = 53) than when treated with conventional therapy (99 +/- 12 ms, n = 77, p < 0.05). The low-amplitude signal (D40) was shorter after thrombolysis (28 +/- 11 vs 33 +/- 12 ms, p < 0.02). Terminal root-mean-square voltage did not differ significantly (41 +/- 24 vs 35 +/- 23 microV). Irrespective of treatment, late potentials were predictive in the complete group (n = 171) for arrhythmic events during follow-up (13 +/- 6 months, range 6 to 24) (hazard ratio 7.7, p < 0.02, Cox proportional-hazards survival analysis), but treatment (streptokinase vs conventional) did not significantly affect outcome when added to the model. It is concluded that thrombolysis prevents the development of late potentials. However, this study does not confirm the hypothesis that prevention of late potentials leads to a decrease in arrhythmic events.

Drug use in pregnancy: a comparative appraisal of data collecting methods

We have compared the reliability of the information about drug therapy and pregnancy retrieved by interviewing patients with that distilled from pharmacy records. In the initial phase of each interview we used the internationally accepted open-ended technique, and extended this with an indication-oriented set of questions and then a set of specific drug-oriented questions. These data were then compared with those from pharmacy records on dispensing for the same patients during their pregnancy. The results suggest that if drug consumption during pregnancy is evaluated by interview, one should not restrict oneself to open-ended questions but should include indication-oriented and, when appropriate, drug-oriented questions. Such specific questions offer the opportunity of detecting the use of over-the-counter medication and of constructing drug use/complaint profiles. By contrast, pharmacy records will give better information in case of long recall periods and in patients with multiple and/or repeated drug use. Investigators should use the complementary elements of both techniques where appropriate.

Drug expectations and drug choices of hospital physicians

OBJECTIVES

To assess whether differences in drug choices of hospital physicians are related to differences in the underlying decision-making process.

DESIGN

A survey study was conducted addressing drug choices in six therapeutic fields with existing interprescriber variations; prescribers and non-prescribers of drugs of which the merits were not sufficiently proven (i.e. the 'target drugs') were compared.

SETTING

A 1000-bed university hospital in The Netherlands.

SUBJECTS

All 85 hospital physicians working in specialities involving one of the selected fields were asked to participate; 72 physicians completed the interviews.

MAIN OUTCOME MEASURES

Comparisons were made regarding three elements of the decision-making process: (1) the physicians' expectations of the target drugs and frequently used alternatives, (2) the weights attached to the principal treatment aspects, and (3) the extent to which their actual choice is based on these expectations and weights.

RESULTS

In three fields, i.e. anti-emetics, vasodilators, and platelet inhibitors, the prescribers of the less desirable target drugs had higher expectations of these drugs in comparison to the non-prescribers. In the other therapeutic fields, choosing target drugs was related either to attaching less importance to side-effects and costs, or to attaching less importance to reports from clinical trials. Twenty of the 46 treatment choices of the prescribers of target drugs could not be predicted from their expressed views as opposed to 5 of the 36 choices of the non-prescribers (P < 0.05).

CONCLUSIONS

Choosing less desirable drugs is not always related to having too high expectations of the drug. Assigning a different importance to certain aspects of the drug and resorting to decision strategies that do not include the weighing of all pros and cons provide alternative explanations for such treatment choices.

Towards understanding treatment preferences of hospital physicians

Seventy-two physicians working in a university hospital in The Netherlands were interviewed to clarify their decision-making process when choosing drugs of preference. Each physician was questioned about the treatment choices for either one or two general case descriptions. The physicians considered only a limited set of different treatment options, on an average 1.7-5.0. Further, the physicians expressed their expectancies as regards various treatment alternatives, and the value or weight they attached to the principle aspects of a treatment. An analytical decision model was used as a reference to gain insight into the extent to which the physicians make decisions based on their own subjective expectancies and values. This model assumes that physicians follow a maximizing strategy by choosing the treatment they personally assess as optimal. It was found that a model including only biomedical expectancies and values predicted the preferred treatment correctly in no more than 53% of the cases. Sometimes, biomedical aspects were disregarded that should have been relevant according to the physicians themselves. Adding aspects of the social environment and experiences improved the prediction of the model substantially; 3 out of 4 treatment preferences could be understood by following an analytical maximizing strategy including biomedical aspects and social aspects and experiences. In the remaining cases, the physicians were not able to describe their decision in terms of this maximizing strategy, which points at the use of alternative decision strategies. One alternative decision strategy mentioned by the physicians was a 'follow-the-routine' decision rule.

Sustained atrial flutter around the tricuspid valve in pigs: differentiation of procainamide (class IA) from flecainide (class IC) and their rate-dependent effects

The wavelength theory considers two determinants of reentry, i.e., refractoriness and conduction velocity. It does not take excitability into account primarily. We evaluated frequency-dependence of excitability and refractoriness before and after flecainide or procainamide administration in relation to termination of reentrant atrial flutter. After making a Y-shaped lesion in the right atrium, we induced 62 flutters (cycle length 171 +/- 15 ms) by electrical stimulation in 15 pigs. Strength-interval curves were determined to assess excitability and refractoriness. Multiple cycle lengths were used to establish rate-dependent changes. Flutter cycle length increased after flecainide (to 290 +/- 67 ms) or procainamide (to 295 +/- 54 ms). The flutters always terminated abruptly (flecainide dose 103 +/- 104 mg, plasma concentration 370 +/- 21 ng/ml; procainamide dose 1,150 +/- 686 mg, concentration 51 +/- 24 mg/l). Flecainide caused an increase in diastolic thresholds from 0.3 +/- 0.2 to 0.8 +/- 0.5 mA (p < 0.006) and procainamide from 0.5 +/- 0.3 to 0.9 +/- 0.5 mA (p < 0.02). The increase in threshold was frequently dependent. Procainamide increased refractoriness at longer cycle lengths (> or = 250 ms), but this effect was abolished at shorter cycle lengths, indicating that only after significant slowing of the rate, prolongation of refractoriness may appear. Thus, both drugs interrupt reentrant flutter mainly by reducing excitability. Subclassification into IA and IC may be less relevant at high rates. Construction of strength-interval curves and assessment of rate-dependent "postrepolarization refractoriness" should be considered when one studies drugs that influence excitability.

Late potentials in a porcine model of anterior wall myocardial infarction and their relation to inducible ventricular tachycardia

In this study, normal values for signal averaged electrocardiographic parameters were assessed in healthy pigs (n = 100) and the development of late potentials after myocardial infarction (n = 41) in relation to inducible ventricular tachycardia was investigated. Normal values are: filtered QRS duration (QRS) < or = 78 msec; root mean square voltage of the averaged QRS complex (V(tot)) > or = 51 microV, and duration of terminal activity below 30 microV (D30) < or = 37 msec. The distribution of the root mean square voltage in the last 30 msec (V30) was biphasic. Two weeks after myocardial infarction, QRS was prolonged from 55 +/- 10 to 66 +/- 19 msec (P < 0.002). D30 was prolonged from 19 +/- 6 msec to 28 +/- 13 (P < 0.002). V30 was decreased from 107 +/- 135 microV to 45 +/- 77 (P < 0.02). The total voltage (V(tot)) was decreased from 195 +/- 78 to 123 +/- 61 microV (P < 0.002). In four pigs (19%) late potentials developed. Sustained ventricular tachycardia was inducible in 11 pigs (52%), ventricular fibrillation in two pigs (10%) and eight pigs (38%) were noninducible. Three of 11 inducible pigs and one of the noninducible pigs had a late potential. The incidence of late potentials and their relation to inducible sustained ventricular tachycardia is comparable to the situation in man. Therefore, this pig model is an attractive alternative to the commonly used dog models.

Differences in vasomotor control between human gastroepiploic and left internal mammary artery

BACKGROUND

Internal mammary artery grafts have a greater long-term patency rate than do saphenous vein grafts. This has in part been attributed to the difference in endothelial function of arterial and venous vessels. The use of the gastroepiploic artery in coronary artery bypass grafting has become popular recently because of its similarity to internal mammary artery. In this study, we compared the endothelial responses of gastroepiploic and left internal mammary arteries to vasoactive substances.

METHODS AND RESULTS

Gastroepiploic and left internal mammary arteries were obtained during surgery from patients undergoing elective coronary artery bypass surgery. Vascular rings of both graft types were studied in organ bath experiments. Relaxation responses to metacholine and sodium nitrite were similar in rings of both arteries. In contrast, bradykinin induced potent relaxations in rings of the gastroepiploic artery but not in rings of the left internal mammary artery. Furthermore, there was a inverse correlation of maximal metacholine-induced relaxations with increasing age.

CONCLUSIONS

The resemblance of relaxations induced by metacholine and sodium nitrite in both gastroepiploic and left internal mammary arteries suggests a similar activation and behavior of the L-arginine pathway in both arteries. The difference in bradykinin-induced relaxations may reflect a prostaglandin metabolism in the gastroepiploic artery different from that in the left internal mammary artery. Furthermore, maximal metacholine-induced relaxation in rings of the left internal mammary artery shows an age dependency that was not observed in rings of the gastroepiploic artery.

The angiotensin converting enzyme inhibitor perindopril improves survival after experimental myocardial infarction in pigs

In this randomized, blinded study the effect of the angiotensin converting enzyme inhibitor perindopril on electrical stability after myocardial infarction in pigs was compared to placebo. The left anterior descending artery was occluded for 45 min. Perindoprilat (0.06 mg/kg, n = 12) or saline (n = 12) was injected 15 min before reperfusion. Treatment was continued till day 13 with perindopril (12 mg, once daily) or placebo. At day 14 an electrophysiologic study was performed. The release of creatine phosphokinase did not differ significantly. During the subsequent days, seven of 12 placebo-treated pigs died (six within 24 h), whereas two of the 12 perindopril-treated pigs died (one within 24 h; p less than 0.04). Sustained ventricular tachycardia was inducible in one of five placebo-treated pigs versus three of 10 perindopril-treated survivors (NS). Late potentials had developed in one placebo-treated pig but not in pigs that received perindopril. Characteristics of infarct border zone heterogeneity (percentages of a reference electrode in viable myocardium) such as a dispersion of current thresholds (127 +/- 96 vs. 238 +/- 463% in perindopril-treated pigs, NS) and refractoriness (9.8 +/- 8.4 vs. 11.9 +/- 6.0% in perindopril-treated pigs, NS) were comparable. This treatment with perindopril significantly improved survival while electrical stability was comparable between survivors. The latter indicates that a comparable electrical stability 2 weeks after myocardial infarction is obtained in perindopril-treated pigs at a significantly higher survival rate.

Captopril modifies the response of infarcted rat hearts to isoprenaline stimulation

In this study the effect of the angiotensin converting enzyme (ACE) inhibitor captopril on beta-receptor responsiveness was investigated in failing rat hearts after experimental myocardial infarction. Infarcted rats were treated for 8 weeks with either captopril added to the drinking water (100 mg/kg/day; n = 5) or drinking water alone (n = 7). Treatment was started 2-3 days before myocardial infarction. A third group of untreated rats without myocardial infarction served as control (n = 6). At the end of the treatment period the hearts were perfused as described by Langendorff, and a cumulative dose-response curve of isoprenaline was obtained in each heart. In comparison with noninfarcted hearts, the response of heart rate and peak pressure rate (dP/dt) to isoprenaline stimulation was significantly depressed in hearts of infarcted rats. Chronic treatment with captopril significantly attenuated the reduced responsiveness to isoprenaline stimulation. This improved responsiveness in captopril-treated rat hearts might be due to prevention of "down-regulation" of myocardial beta-adrenoceptors. Other factors should also be considered, such as prevention of structural alterations in the noninfarcted myocardium, e.g., myocardial hypertrophy and fibrosis. Differences in infarct size did not play an important role, since infarct size was comparable in both groups of infarcted rats. This partial preservation of beta-adrenergic responsiveness was accompanied by a significant reduction in right ventricular weight and lung weight, suggesting that captopril also improved the signs of heart failure. Therefore, the results of this study indicate that early ACE inhibition in myocardial infarction may be useful in preventing deterioration of cardiac function.