Carbon dioxide-induced emotion and respiratory symptoms in healthy volunteers.

A number of evidences have established that panic and respiration are closely related. Clinical studies indicated that respiratory sensations constitute a discrete cluster of panic symptoms and play a major role in the pathophysiology of panic. The aim of the present study was to explore the phenomenology of an experimental model of panic in healthy volunteers based on the hypothesis that: (1) we can isolate discrete clusters of panic symptoms, (2) respiratory symptoms represent a distinct cluster of panic symptoms, and (3) respiratory symptoms are the best predictor of the subjective feeling of panic, as defined in the DSM IV criteria.Sixty-four healthy volunteers received a double inhalation of four mixtures containing 0, 9, 17.5 and 35% CO(2,) respectively, in a double-blind, cross-over, random design. An electronic visual analog scale and the Panic Symptom List (PSL) were used to assess subjective 'fear/discomfort' and panic symptoms, respectively. Statistical analyses consisted of Spearman's correlations, a principal component factor analysis of the 13 PSL symptoms, and linear regressions analyses.The factor analysis extracted three clusters of panic symptoms: respiratory, cognitive, and neurovegetative (r(2)=0.65). Respiratory symptoms were highly related to subjective feeling of fear/discomfort specifically in the CO(2)-enriched condition. Moreover, the respiratory component was the most important predictor of the subjective feeling of 'fear/discomfort' (beta=0.54).The discrete clusters of symptoms observed in this study were similar to those elicited in panic attacks naturally occurring in patients affected by panic disorder. Consistent with the idea that respiration plays a crucial role in the pathophysiology of panic, we found that respiratory symptoms were the best predictors the subjective state defined in the DSM IV criteria for panic.

Carbon dioxide inhalation induces dose-dependent and age-related negative affectivity.

BACKGROUND: Carbon dioxide inhalation is known to induce an emotion similar to spontaneous panic in Panic Disorder patients. The affective response to carbon dioxide in healthy subjects was not clearly characterized yet. METHODOLOGY/PRINCIPAL FINDINGS: Sixty-four healthy subjects underwent a double inhalation of four mixtures containing respectively 0, 9, 17.5 and 35% CO(2) in compressed air, following a double blind, cross-over, randomized design. Affective responses were assessed according to DSM IV criteria for panic, using an Electronic Visual Analogue Scale and the Panic Symptom List. It was demonstrated that carbon dioxide challenges induced a dose dependent negative affect (p<0.0001). This affect was semantically identical to the DSM IV definition of panic. Older individuals were subjectively less sensitive to Carbon Dioxide (p<0.05). CONCLUSIONS/SIGNIFICANCE: CO(2) induced affectivity may lay on a continuum with pathological panic attacks. Consistent with earlier suggestions that panic is a false biological alarm, the affective response to CO(2) may be part of a protective system triggered by suffocation and acute metabolic distress.

Exhaustion is associated with low macrophage migration inhibitory factor expression in patients with coronary artery disease.

OBJECTIVE: Macrophage migration inhibitory factor (MIF), a protein secreted by immune cells and the pituitary gland, may be associated with coronary artery disease (CAD) and the mental state of coronary patients. The first origin of MIF suggests positive, the second negative associations. The aim of this study was to explore the direction of the association of MIF with CAD and of MIF with exhaustion, if any. METHODS: Participants were 194 patients who had been recently treated by percutaneous coronary intervention (PCI) and who were exhausted at the start of the study. Half entered a behavioral intervention program. MIF, C-reactive protein, interleukin (IL)-6, IL-1 receptor antagonist, and neopterin were measured in blood collected 6 weeks after PCI (baseline) and 6 and 18 months after baseline. A single measurement of MIF was also available for 129 age- and sex-matched healthy individuals (reference group). RESULTS: At baseline, MIF in patients undergoing PCI was significantly lower than in the reference group (p < .01). New cardiac events occurred twice as often in the lowest quartile than in the highest quartile of MIF concentrations. However, the association was not significant (chi(2) = 2.27; df = 3; p = .52). During follow up, MIF concentrations increased significantly in patients undergoing PCI (p < .001). At 18 months, MIF concentrations were significantly lower in the exhausted patients than in the nonexhausted patients (p = .02). hsCRP, IL-1ra, IL-6, and neopter in concentrations did not change over this time period. CONCLUSIONS: The data are suggestive of a negative association of MIF with CAD and of MIF with exhaustion. The observation that those patients who remained exhausted had lower concentrations of MIF fits into earlier observations that suggested that exhausted coronary patients may be characterized by a hypoactivity of the hypothalamic-pituitary-adrenocortical axis.

Effects of a behavioural intervention on quality of life and related variables in angioplasty patients: results of the EXhaustion Intervention Trial.

OBJECTIVES: The EXhaustion Intervention Trial investigated the effect of a behavioural intervention programme on exhaustion, health-related quality of life (HRQL), depression, anxiety, hostility, and anginal complaints in angioplasty patients who felt exhausted after percutaneous coronary intervention (PCI). METHODS: Seven hundred ten patients were randomized into an intervention group and a usual care control group. The group intervention focused on stressors leading to exhaustion and on support of recovery. HRQL (measured by the MacNew questionnaire), exhaustion [measured by the Maastricht Questionnaire and the Maastricht Interview Vital Exhaustion (MIVE)], anxiety (measured by the State-Trait Inventory), and depression (measured by the structured clinical interview for DSM-IV) were assessed at intake and at 6 and 18 months. Presence of anginal complaints was assessed at 18 months. RESULTS: The intervention had a significant beneficial effect on all psychological factors except hostility and on the presence of anginal complaints. The effect of the intervention on exhaustion, as assessed by the MIVE, was modified by a previous history of coronary artery disease (CAD). Gender modified the effect of the intervention on exhaustion and on anxiety, the strongest effect being observed in women. CONCLUSIONS: The behavioural intervention improved HRQL and related psychological factors. Somatic comorbidity and a history of CAD limited the effect of the intervention.

Inflammatory markers predict late cardiac events in patients who are exhausted after percutaneous coronary intervention.

Chronic inflammation is one of the main underlying mechanisms in the development of coronary artery disease (CAD). We investigated the prognostic value of inflammatory markers for cardiac events occurring more than 6 months after percutaneous coronary intervention (PCI), i.e. late cardiac events, furthermore we investigated the temporal stability of these markers. Exhausted patients (234) recently treated by successful PCI were studied. Serum samples collected about 6 weeks after PCI (baseline), 6 and 18 months after baseline were analyzed for CRP, IL-6, tumour necrosis factor (TNF-alpha), IL-10, IL-1ra, IL-8 and neopterin. In the mean cardiac follow-up of 24 months, 25 late cardiac events occurred. Cox proportional hazards analysis was used to determine the prognostic value. Elevated concentrations of IL-6 at baseline and 6 months later increased the risk of late cardiac events (RR 3.9, CI 1.7-9.0, p 0.00 and RR 3.6, CI 1.6-8.5, p 0.00). Elevated concentrations of CRP and IL-10 at baseline also increased the risk of late cardiac events (RR 2.5, CI 1.1-5.7, p 0.04 and RR 2.5, CI 1.1-5.6, p 0.03) as did IL-1 receptor antagonist at 6 months (RR 2.6, CI 1.1-6.1, p 0.04). Temporal stability was high for most markers, but highest for IL-6. These results support the assumption that chronic inflammation is a pathophysiological mechanism in the development of CAD.

Novel conformation-specific antibodies against matrix gamma-carboxyglutamic acid (Gla) protein: undercarboxylated matrix Gla protein as marker for vascular calcification.

OBJECTIVE: Matrix gamma-carboxyglutamic acid (Gla) protein (MGP), a vitamin K-dependent protein, is a potent in vivo inhibitor of arterial calcification. We hypothesized that low endogenous production of MGP and impaired carboxylation of MGP may contribute to the development or the progression of vascular disease. METHODS AND RESULTS: Novel conformation-specific antibodies against MGP were used for immunohistochemistry of healthy and sclerotic arteries. In healthy arteries, MGP was mainly displayed around the elastin fibers in the tunica media. The staining colocalized with that for carboxylated MGP, whereas undercarboxylated MGP (ucMGP) was not detected. In atherosclerotic arteries, ucMGP was found in the intima, where it was associated with vesicular structures. In Mönckeberg's sclerosis of the media, ucMGP was localized around all areas of calcification. The results indicate that ucMGP is strongly associated with vascular calcification of different etiologies. In a separate study, serum MGP concentrations in a cohort of 172 subjects who had undergone percutaneous coronary intervention were significantly reduced compared with an apparently healthy population. CONCLUSIONS: These data show that impaired carboxylation of MGP is associated with intimal and medial vascular calcification and suggest the essentiality of the vitamin K modification to the function of MGP as an inhibitor of ectopic calcification.

Sleep complaints in panic disorder patients.

Patients with anxiety disorders often report difficulty sleeping. The present study assesses the prevalence of sleep complaints in panic disorder (PD) patients, compares them with sleep complaints in a normal population, and investigates the role of comorbid depression and nocturnal panic attacks in sleep complaints in the PD patients. Seventy PD patients and 70 healthy controls were asked about their subjective sleep characteristics by means of the Sleep-Wake Experience List, which assesses sleep/arousal complaints over a 24-hour period. Sixty-seven percent of the PD patients reported sleep complaints, compared with 20% of the controls. Eighty-six percent of the depressed PD patients and 59% of the nondepressed had sleep difficulties; 77% of the PD patients with nocturnal panic attacks reported sleep complaints, versus 53% of the PD patients without nocturnal panic. It is concluded that PD patients demonstrate a higher prevalence of sleep complaints than normal controls; this can only partly be explained by comorbid depression, and cannot be explained by the presence of nocturnal panic attacks.

Effects of treating exhaustion in angioplasty patients on new coronary events: results of the randomized Exhaustion Intervention Trial (EXIT).

BACKGROUND: Extreme fatigue is a common complaint in percutaneous coronary intervention (PCI) patients, and is associated with an increased risk for new cardiac events. The objective of the Exhaustion Intervention Trial (EXIT) was to determine whether a behavioral intervention on exhaustion reduces the risk of a new coronary event after PCI. METHODS AND RESULTS: Seven hundred ten consecutive patients, ages 35 to 68 years, who felt exhausted after PCI were randomized into an intervention group and a usual-care group. The intervention was based on group therapy focusing on stressors leading to exhaustion, and on support for recovery by promoting rest and making rest more efficient. One month after PCI, 50% of the patients felt exhausted. The intervention reduced the odds of remaining exhausted at 18 months by 56% in those without a previous history of coronary artery disease (CAD) (OR = 0.44; 95% CI 0.29-0.66), but had no effect on exhaustion in those with a history of CAD (OR = 0.93; 95% CI 0.56-1.55; p = .78). The intervention did not reduce the risk of a new coronary event within 2 years (RR = 1.14; 95%CI 0.82-1.57). Post-hoc analyses suggest that the effect of the intervention was limited by a positive history of CAD, the presence of a chronic, painful condition (especially rheumatism), and by opposite effects on early and late cardiac events. CONCLUSION: A behavioral intervention in PCI patients has a beneficial effect on feelings of exhaustion. It could not be demonstrated that the intervention reduces the risk of a new coronary event within 2 years.

Characteristics and performance of an immunosorbent assay for human matrix Gla-protein.

BACKGROUND: Matrix gammacarboxyglutamate (Gla)-protein (MGP) is a strong inhibitor of soft tissue calcification and is mainly produced by chondrocytes and vascular smooth muscle cells (VSMCs). MGP-deficient mice have extensive calcifications of cartilage and arteries leading to osteopenia, fractures and blood vessel ruptures. Promotor polymorphisms resulting in decreased expression levels were found to be associated with an increased risk for cardiovascular disease in humans. METHODS: Recently, an ELISA-based assay has become available with which MGP may be detected in the circulation. The principle of the test kit is that of a competitive immunoassay using a monoclonal antibody against MGP bound to the microtiter plate. RESULTS: Here, we report on a critical evaluation of this assay and its potential diagnostic utility in diseases associated with the degeneration of the arterial vessel wall and cartilage. The biochemical performance of the kit is satisfactory, and significant differences were found between a number of patient cohorts and the reference population. Serum MGP concentrations were significantly decreased in patients with angina pectoris and in various cartilage diseases. CONCLUSIONS: The assay allows comparison of groups and may become a suitable marker for risk assessment or diagnosis in cardiovascular disease and osteoarthritis.

Herpes viruses, cytokines, and altered hemostasis in vital exhaustion.

OBJECTIVE: Infections with herpes viruses have been implicated in the pathogenesis of atherosclerosis. We tested the hypothesis that vital exhaustion (VE) is associated with multiple herpesvirus infections, such as herpes simplex virus, varicella-zoster virus, Epstein-Barr virus, and cytomegalovirus, and with an increase in pathogen burden (ie, the aggregated seropositivity to immunoglobulin G antibodies for herpes simplex virus, varicella-zoster virus, Epstein-Barr virus, and cytomegalovirus). In addition, we examined the association of VE and pathogen burden with measures of hemostasis and inflammation. METHODS: Blood samples were drawn from 29 men with VE and 30 male control subjects, all healthy and nonsmokers, to assess serological evidence of infection and measures of hemostasis and inflammation. RESULTS: VE is associated with a relatively high pathogen burden, altered hemostasis, and higher levels of cytokines, such as interleukin-6. Across all subjects, a relatively high pathogen burden was also associated with altered hemostasis but not with increased cytokine levels. The interaction of VE with pathogen burden revealed significant linear increases in measures of hemostasis and inflammation. Finally, immunoglobulin G antibody titer levels of individual herpesvirus infections were not associated with hemostatic measures or with cytokines. CONCLUSIONS: We conclude that stress-related alterations in hemostasis and inflammation are not necessarily linked to one particular herpesvirus infection but rather to an increase in aggregated seropositivity to herpesvirus infections.

Diurnal variations in coagulation and fibrinolysis in vital exhaustion.

OBJECTIVE: Vital exhaustion (VE) predicts a first myocardial infarction (MI) and new cardiac events after a coronary angioplasty. To explore potential underlying pathophysiological mechanisms, we tested whether VE is associated with more pronounced diurnal variations in hemostasis. METHODS: Blood was drawn from 29 VE and 30 control males, all healthy and nonsmokers, to assess hemostatic measures at 7:00 AM and 6:00 PM. RESULTS: All measures of fibrinolysis were in their normal range and showed significant diurnal variations. These variations were more pronounced in VE as all fibrinolytic measures were significantly higher in VE at 7:00 AM and similar to those of controls at 6:00 PM, thus supporting our hypothesis with respect to fibrinolysis. Diurnal decreases in tPA and tPA-PAI ranged from 1.5 (VE) to 1.3 (controls), whereas the diurnal decrease in PAI-1 was more than fourfold in VE and 2.7-fold in controls. This suggests a decreased fibrinolytic capacity in VE during the early morning. All coagulation measures were in their normal range, and prothrombin fragment 1+2 (F1+2), thrombin-antithrombin complexes, and activated factor VII showed significant diurnal variations. These variations were similar in VE and control individuals, thus not supporting our hypothesis with respect to coagulation. Finally, F1+2 and fibrinogen were both significantly higher throughout the day in VE. CONCLUSIONS: VE is associated with decreased early morning fibrinolysis and increased fibrinogen levels throughout the day. These hemostatic changes may promote thrombus formation and provide a potential pathophysiological mechanism by which VE is related to MI and its circadian variation.

L-5-hydroxytryptophan induced increase in salivary cortisol in panic disorder patients and healthy volunteers.

BACKGROUND: Hypersensitivity of brain serotonin receptors has been proposed as a causal mechanism in the pathophysiology of panic disorder. This theory can be tested, using serotonergic stimulation of the HPA axis. Up to now, plasma cortisol has generally been used as the outcome measure in such studies. Assessment of salivary cortisol is a non-invasive alternative to measure HPA axis activity. METHOD: Salivary cortisol levels were measured in 24 panic disorder patients and 24 healthy volunteers, following ingestion of 200 mg L-5-hydroxytryptophan or placebo. RESULTS: A significant rise in cortisol was observed in both patients and controls following ingestion of L-5-hydroxytryptophan. No such effects were seen in the placebo condition. CONCLUSION: The results show that L-5-hydroxytryptophan stimulated salivary cortisol is a useful probe of serotonin function in healthy volunteers as well as panic disorder patients, and provide some evidence against a serotonin receptor hypersensitivity in panic disorder.

Acute L-5-hydroxytryptophan administration inhibits carbon dioxide-induced panic in panic disorder patients.

Previous research showed that lowering the availability of serotonin to the brain by tryptophan depletion increases the vulnerability of panic disorder patients for an experimental 35% CO(2) panic challenge. The results also suggested that increased availability of serotonin inhibits the response to such a challenge. In the present study, this latter possibility is examined. The reaction of 24 panic disorder patients and 24 healthy volunteers to a 35% CO(2) panic challenge was assessed following administration of 200-mg L-5-hydroxytryptophan (the immediate precursor of serotonin) or placebo. L-5-Hydroxytryptophan significantly reduced the reaction to the panic challenge in panic disorder patients, regarding subjective anxiety, panic symptom score and number of panic attacks, as opposed to placebo. No such effect was observed in the healthy volunteers. L-5-Hydroxytryptophan acts to inhibit panic, which supports a modulatory role of serotonin in panic disorder.