Differences in potential biomarkers of delirium between acutely ill medical and elective cardiac surgery patients.

BACKGROUND/AIMS: The pathophysiology of delirium is poorly understood. Increasing evidence suggests that different pathways might be involved in the pathophysiology depending on the population studied. The aim of the present study was to investigate potential differences in mean plasma levels of neopterin, amino acids, amino acid ratios and homovanillic acid between two groups of patients with delirium. METHODS: Data from acutely ill medical patients aged 65 years and older, and patients aged 70 years and older undergoing elective cardiac surgery, were used. Differences in biomarker levels between the groups were investigated using univariate ANOVA with adjustments for age, sex, comorbidities, C-reactive protein (CRP) and the estimated glomerular filtration rate (eGFR), where appropriate. Linear regression analysis was used to identify potential determinants of the investigated biochemical markers. RESULTS: Eighty patients with delirium were included (23 acutely ill medical patients and 57 elective cardiac surgery patients). After adjustment, higher mean neopterin levels (93.1 vs 47.3 nmol/L, P=0.001) and higher phenylalanine/tyrosine ratios (1.39 vs 1.15, P=0.032) were found in acutely ill medical patients when compared to elective cardiac surgery patients. CRP levels were positively correlated with neopterin levels in acutely ill medical patients, explaining 28.4% of the variance in neopterin levels. eGFR was negatively correlated with neopterin in elective cardiac surgery patients, explaining 53.7% of the variance in neopterin levels. CONCLUSION: In this study, we found differences in mean neopterin levels and phenylalanine/tyrosine ratios between acutely ill medical and elective cardiac surgery patients with delirium. Moreover, our findings may suggest that in acutely ill medical patients, neopterin levels are mainly determined by inflammation/oxidative stress whereas in elective cardiac surgery patients, neopterin levels are mainly driven by renal function/fluid status. These findings suggest that the markers and pathways that might be involved in the pathophysiology of delirium may differ between specific groups of patients.

Cycloid psychoses in the psychosis spectrum: evidence for biochemical differences with schizophrenia.

Cycloid psychoses (CP) differ from schizophrenia regarding symptom profile, course, and prognosis and over many decades they were thought to be a separate entity within the psychosis spectrum. As to schizophrenia, research into the pathophysiology has focused on dopamine, brain-derived neurotrophic factor, and glutamate signaling in which, concerning the latter, the N-methyl-d-aspartate receptor plays a crucial role. The present study aims to determine whether CP can biochemically be delineated from schizophrenia. Eighty patients referred for psychotic disorders were assessed with the Comprehensive Assessment of Symptoms and History, and (both at inclusion and after 6 weeks of antipsychotic treatment) with the Positive and Negative Syndrome Scale and Clinical Global Impression. From 58 completers, 33 patients were diagnosed with schizophrenia and ten with CP according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, and Leonhard criteria, respectively. Fifteen patients were diagnosed with other disorders within the psychosis spectrum. At both time points, blood levels of the dopamine metabolite homovanillic acid, brain-derived neurotrophic factor, and amino acids related to glutamate neurotransmission were measured and compared with a matched control sample. Patients with CP showed a significantly better response to antipsychotic treatment as compared to patients with schizophrenia. In CP, glycine levels were elevated and tryptophan levels were lowered as compared to schizophrenia. Glutamate levels were increased in both patient groups as compared to controls. These results, showing marked differences in both treatment outcome and glutamate-related variable parameters, may point at better neuroplasticity in CP, necessitating demarcation of this subgroup within the psychosis spectrum.

Increased CSF levels of aromatic amino acids in hip fracture patients with delirium suggests higher monoaminergic activity.

BACKGROUND: To examine whether delirium in hip fracture patients was associated with changes in the levels of amino acids and/or monoamine metabolites in cerebrospinal fluid (CSF) and serum. METHODS: In this prospective cohort study, 77 patients admitted with an acute hip fracture to Oslo University Hospital, Norway, were studied. The concentrations of amino acids in CSF and serum were determined by high performance liquid chromatography. The patients were assessed daily for delirium by the Confusion Assessment Method (pre-operatively and post-operative day 1-5 (all) or until discharge (delirious patients)). Pre-fracture dementia status was decided by an expert panel. Serum was collected pre-operatively and CSF immediately before spinal anesthesia. RESULTS: Fifty-three (71 %) hip fracture patients developed delirium. In hip fracture patients without dementia (n = 39), those with delirium had significantly higher CSF levels of tryptophan (40 % higher), tyrosine (60 % higher), phenylalanine (59 % higher) and the monoamine metabolite 5-hydroxyindoleacetate (23 % higher) compared to those without delirium. The same amino acids were also higher in CSF in delirious patients with dementia (n = 38). The correlations between serum and CSF amino acid levels were poor. CONCLUSION: Higher CSF levels of monoamine precursors in hip fracture patients with delirium suggest a higher monoaminergic activity in the central nervous system during delirium in this patient group.

Cerebrospinal fluid levels of neopterin are elevated in delirium after hip fracture.

BACKGROUND: The inflammatory cell product neopterin is elevated in serum before and during delirium. This suggests a role for disordered cell-mediated immunity or oxidative stress. Cerebrospinal fluid (CSF) neopterin levels reflect brain neopterin levels more closely than serum levels. Here we hypothesized that CSF neopterin levels would be higher in delirium. METHODS: In this prospective cohort study, 139 elderly patients with acute hip fracture were recruited in Oslo and Edinburgh. Delirium was diagnosed with the confusion assessment method performed daily pre-operatively and on the first 5 days post-operatively. Paired CSF and blood samples were collected at the onset of spinal anaesthesia. Neopterin levels were measured using high-performance liquid chromatography. RESULTS: Sixty-four (46 %) of 139 hip fracture patients developed delirium perioperatively. CSF neopterin levels were higher in delirium compared to controls (median 29.6 vs 24.7 nmol/mL, p = 0.003), with highest levels in patients who developed delirium post-operatively. Serum neopterin levels were also higher in delirium (median 37.0 vs 27.1 nmol/mL, p = 0.003). CSF neopterin remained significantly associated with delirium after controlling for relevant risk factors. Higher neopterin levels were associated with poorer outcomes (death or new institutionalization) 1 year after surgery (p = 0.02 for CSF and p = 0.03 for serum). CONCLUSIONS: This study is the first to examine neopterin in CSF from patients with delirium. Our findings suggest potential roles for activation of cell-mediated immune responses or oxidative stress in the delirium process. High levels of serum or CSF neopterin in hip fracture patients may also be useful in predicting poor outcomes.

Potential Influence of Aspirin on Neopterin and Tryptophan Levels in Patients with a Delirium.

In an in vitro study, it was found that aspirin might decrease neopterin production and tryptophan degradation. The aim of the present study was to evaluate the possible association between aspirin use and mean neopterin and tryptophan levels in patients with and without a delirium and whether the use of aspirin is associated with a decreased prevalence of delirium. Neopterin and tryptophan levels were determined previously in acutely ill admitted patients aged ≥65 years. The possible influence of aspirin on mean levels of neopterin and tryptophan was investigated with univariate analysis of variance in adjusted models. Eighty-three patients were included; 22 had a delirium. In patients without a delirium (no aspirin (n = 31) versus aspirin (n = 27)), mean neopterin levels were 47.0 nmol/L versus 43.6 nmol/L (p = 0.645) and tryptophan levels were 33.1 µmol/L versus 33.9 µmol/L (p = 0.816). In patients with a delirium (no aspirin (n = 13) versus aspirin (n = 9)), mean neopterin levels were 77.8 nmol/L versus 71.1 nmol/L (p = 0.779) and tryptophan levels were 22.4 µmol/L versus 27.3 µmol/L (p = 0.439). No difference was found in the distribution of aspirin users between patients with and without a delirium. In this study, we found that the use of aspirin had no significant effect on mean levels of neopterin and tryptophan. However, the raw data suggest that there might be a potential influence in patients with a delirium. Aspirin use was not associated with a decreased prevalence of delirium.

Relationship between plasma homovanillic acid and outcome in patients with psychosis spectrum disorders.

BACKGROUND: Psychosis spectrum disorders, especially schizophrenia, have been linked to disturbed dopaminergic activity in the brain. Plasma homovanillic acid (pHVA) levels partly represent dopaminergic metabolism in the central nervous system. In the present study associations between (changes in) pHVA levels, symptom severity and symptomatic improvement in patients with psychoses were investigated. METHODS: From a total of 80 patients, 58 fulfilled all inclusion criteria and their symptom profile and severity were assessed by means of the Comprehensive Assessment of Symptoms and History (CASH), the Positive and Negative Syndrome Scale (PANSS) and the Clinical Global Impression Scale for Severity and Improvement (CGI-S/CGI-I) at baseline and after 6 weeks of antipsychotic treatment. After inclusion, all patients were prescribed first- or second-generation antipsychotics by their treating psychiatrist. A total of 12 patients had first-episode psychosis (FEP). At both time points, pHVA levels were measured. Subsequently, pHVA levels were compared with an age-matched control sample and changes in pHVA levels (ΔpHVA) after treatment were associated with clinical parameters. RESULTS: Before analyses, data were scrutinized for possible confounders, particularly gender, smoking, medication status (including antipsychotic class), and recent drug use. The pHVA levels in patients were not different from those in controls. Treatment resulted in a significant decrease of all parameters. Symptomatic improvement as well as ΔpHVA was most pronounced in FEP patients. CONCLUSION: These findings show that patients with FEP have a more favourable outcome than non-FEP patients and that greater ΔpHVA also suggests that FEP patients still have the capacity to adjust dopaminergic neurotransmission.

Disturbed Serotonergic Neurotransmission and Oxidative Stress in Elderly Patients with Delirium.

BACKGROUND: Oxidative stress and disturbances in serotonergic and dopaminergic neurotransmission may play a role in the pathophysiology of delirium. AIMS: In this study, we investigated levels of amino acids, amino acid ratios and levels of homovanillic acid (HVA) as indicators for oxidative stress and disturbances in neurotransmission. METHODS: Plasma levels of amino acids, amino acid ratios and HVA were determined in acutely ill patients aged ≥65 years admitted to the wards of Internal Medicine and Geriatrics of the Erasmus University Medical Center and the ward of Geriatrics of the Havenziekenhuis, Rotterdam, The Netherlands. Differences in the biochemical parameters between patients with and without delirium were investigated by analysis of variance in models adjusted for age, gender and comorbidities. RESULTS: Of the 86 patients included, 23 had delirium. In adjusted models, higher mean phenylalanine/tyrosine ratios (1.34 vs. 1.14, p = 0.028), lower mean tryptophan/large neutral amino acids ratios (4.90 vs. 6.12, p = 0.021) and lower mean arginine levels (34.8 vs. 45.2 µmol/l, p = 0.022) were found in patients with delirium when compared to those without. No differences were found in HVA levels between patients with and without delirium. CONCLUSION: The findings of this study suggest disturbed serotonergic neurotransmission and an increased status of oxidative stress in patients with delirium.

Neopterin: a potential biomarker for delirium in elderly patients.

BACKGROUND/AIMS: The diagnosis of delirium is not supported by specific biomarkers. In a previous study, high neopterin levels were found in patients with a postoperative delirium. In the present study, we investigated levels of neopterin, interleukin-6 (IL-6) and insulin-like growth factor-1 (IGF-1) in acutely ill admitted elderly patients with and without a delirium. METHODS: Plasma/serum levels of neopterin, IL-6 and IGF-1 were determined in patients aged ≥65 years admitted to the wards of Internal Medicine and Geriatrics. Differences in biomarker levels between patients with and without a delirium were investigated by the analysis of variance in models adjusted for age, gender, comorbidities and eGFR (when appropriate). RESULTS: Eighty-six patients were included; 23 of them with a delirium. In adjusted models, higher mean levels of neopterin (70.5 vs. 45.9 nmol/l, p = 0.009) and IL-6 (43.1 vs. 18.5 pg/ml, p = 0.034) and lower mean levels of IGF-1 (6.3 vs. 9.3 nmol/l, p = 0.007) were found in patients with a delirium compared to those without. CONCLUSIONS: The findings of this study suggest that neopterin might be a potential biomarker for delirium which, through oxidative stress and activation of the immune system, may play a role in the pathophysiology of delirium.

Acute serotonin depletion releases motivated inhibition of response vigour.

RATIONALE: The neurotransmitter serotonin has long been implicated in the motivational control of behaviour. Recent theories propose that the role of serotonin can be understood in terms of an interaction between a motivational and a behavioural activation axis. Experimental support for these ideas, however, has been mixed. OBJECTIVES: In the current study, we aimed to investigate the role of serotonin (5HT) in behavioural vigour as a function of incentive motivation. METHODS: We employed dietary acute tryptophan depletion (ATD) to lower the 5HT precursor tryptophan during the performance of a speeded visual discrimination task. Feedback valence and feedback probability were manipulated independently and cued prior to target onset. On feedback trials, fast correct responses led to either reward or avoidance of punishment, while slow or incorrect responses led to reward omission or punishment. RESULTS: We show that behavioural responding is inhibited under high incentive motivation (i.e. high-feedback probability) at baseline 5HT levels and that lowering these leads to behavioural disinhibition, while leaving accuracy unaffected. Surprisingly, there were no differential effects of motivational valence, with 5HT depletion releasing behavioural inhibition under both appetitive and aversive motivation. CONCLUSIONS: Our findings extend current theories on the role of 5HT in behavioural inhibition by showing that reductions in serotonin lead to increased behavioural vigour only if there is a motivational drive to inhibit behaviour at baseline.

The tryptophan kynurenine pathway, neopterin and IL-6 during vulvectomy and abdominal hysterectomy.

BACKGROUND: Surgery has wide ranging immunomodulatory properties of which the mechanism is poorly understood. In order to investigate how different types of surgery influence inflammation, we designed a longitudinal observational study investigating two inflammatory profiles of two separate patient groups undergoing gynaecological operations of differing severity. In addition to measuring the well known inflammatory markers neopterin and IL-6, we also determined the kynurenine/tryptophan ratio. This study was a prospective, single center, two-armed observational study involving 28 female patients. Plasma levels of tryptophan, kynurenine, neopterin and IL-6 were determined from samples taken at: 24 hrs pre-operative, prior to induction, ten minutes before the operation was expected to end, and at 24 and 96 hours post operative in patients undergoing abdominal hysterectomy and vulvectomy. RESULTS: There were 15 and 13 patients included in the vulvectomy and abdominal hysterectomy groups, respectively. In this study we show that anesthesia and surgery significantly increases the enzyme activity of indoleamine 2, 3 dioxygenase (IDO) as measured by the kynurenine/tryptophan ratio (P=0.003), while maintaining stable neopterin levels. However, abdominal hysterectomy causes a considerable IL-6 increase (P<0.001). CONCLUSION: Surgery and associated anesthesia cause a significant tryptophan level decrease while significantly increasing IDO activity. Both types of surgery produce nearly identical neopterin time curve relationships, with no significant change occurring in either group. However, even though neopterin is unaffected by the severity of surgery, IL-6 responded to surgical invasiveness by revealing a significant increase during abdominal hysterectomy.

Tryptophan depletion in chronic fatigue syndrome, a pilot cross-over study.

BACKGROUND: Chronic fatigue syndrome (CFS) is still an enigmatic disorder. CFS can be regarded as a complex disorder with tremendous impact on lives of CFS-patients. Full recovery without treatment is rare. A somatic explanation for the fatigue is lacking. There is clinical and experimental evidence implicating enhanced serotonergic neurotransmission in CFS. Genetic studies and imaging studies support the hypothesis of upregulated serotonin system in CFS. In line with the hypothesis of an increased serotonergic state in CFS, we performed a randomised clinical trial investigated the effect of 5-HT3 receptor antagonism in CFS. No benefit was found of the 5-HT3 receptor antagonist ondansetron compared to placebo.To further investigate the involvement of serotonin in CFS we performed a placebo controlled cross over pilot study investigating the effect of Acute Tryptophan Depletion. FINDINGS: Five female CFS-patients who met the US Center for Disease Control and Prevention criteria for CFS were recruited. There were two test days, one week apart. Each participant received placebo and ATD. To evaluate the efficacy of the ATD procedure tryptophan and the large neutral amino acids were measured. The outcome measures were fatigue severity, concentration and mood states. ATD resulted in a significant plasma tryptophan to large neutral amino acid ratio reduction of 96%. There were no significant differences in fatigue-, depression and concentration between the placebo- and ATD condition. CONCLUSIONS: These first five CFS-patients did not respond to the ATD procedure. However, a much larger sample size is needed to draw final conclusions on the hypothesis of an increased serotonergic state in the pathophysiology of CFS. TRIAL REGISTRATION: ISRCTN07518149.

BDNF and S100B in psychotic disorders: evidence for an association with treatment responsiveness.

OBJECTIVE: Brain-derived neurotrophic factor (BDNF) and S100B are involved in brain plasticity processes and their serum levels have been demonstrated to be altered in patients with psychoses. This study aimed to identify subgroups of patients with psychotic disorders across diagnostic boundaries that show a specific symptom profile or response to treatment with antipsychotics, by measuring serum levels of BDNF and S100B. METHODS: The study sample consisted of 58 patients with DSM-IV psychotic disorders. Comprehensive Assessment of Symptoms and History (CASH), Positive and Negative Syndrome Scale (PANSS) and Clinical Global Impression scale for severity and improvement (CGI-S/CGI-I) were applied at baseline and after 6 weeks of antipsychotic treatment. At both time points, serum levels of BDNF and S100B were measured and compared with a matched control sample. RESULTS: Baseline BDNF and S100B levels were significantly lower in patients as compared with controls and did not change significantly during treatment. Dividing the patient sample according to baseline biochemical parameters (low and high 25% and middle 50%), no differences in symptom profiles or outcome were found with respect to BDNF. However, the subgroups with low and high S100B levels had higher PANSS scores than the middle subgroup. In addition, the high subgroup still showed significantly more negative symptoms after treatment, whereas the low subgroup showed more positive symptoms compared with the other subgroups. CONCLUSION: Serum levels of BDNF and S100B are lowered in patients with psychotic disorders across diagnostic boundaries. The differences between high and low S100B subgroups suggest a relationship between S100B, symptom dimensions and treatment response, irrespective of diagnostic categories.

Effect of major and minor surgery on plasma levels of arginine, citrulline, nitric oxide metabolites, and ornithine in humans.

OBJECTIVE: To determine the effect of surgical invasiveness on plasma levels of arginine, citrulline, ornithine, and nitric oxide (NO) in humans. BACKGROUND: Surgical trauma may have a profound effect on the metabolism of NO. However, human studies reported both increased and decreased NO levels after hemorrhagic shock. Arginine, citrulline, and ornithine are key amino acids involved in NO metabolism, but studies evaluating these amino acids together with NO and during 2 types of surgery are lacking. This study tests the hypothesis that major surgery has a more profound effect on plasma levels of arginine, citrulline, NO, and ornithine than minor surgery. METHODS: Fifteen patients undergoing minor surgery (vulvectomy) and 13 patients undergoing major surgery (laparotomy) were prospectively followed up for 4 days. Plasma was collected for evaluation of levels of arginine, citrulline, NO, and ornithine. RESULTS: Throughout the experiment, arginine levels did not significantly differ between experimental groups. Perioperative plasma citrulline levels were significantly lower in the laparotomy group than in the vulvectomy group, whereas both groups showed a decrease in citrulline levels at the end of the operation and 24 hours postoperatively. Roughly the same pattern was seen for plasma NO and ornithine levels. However, ornithine levels in the laparotomy group showed a more drastic decrease at the end of the operation and 24 hours postoperatively than citrulline and NO levels. CONCLUSIONS: The level of surgical invasiveness has the most profound effect on plasma levels of ornithine. In addition, heavier surgical trauma is paired with lower postoperative levels of citrulline and NO metabolites than lighter surgery. It is suggested that surgical trauma stimulates the laparotomy group to consume significantly more ornithine, possibly for use in wound healing.

Potential neuroprotective effects of oxyresveratrol against traumatic injury.

Oxyresveratrol is a potent antioxidant and free-radical scavenger found in mulberry wood (Morus alba L.) with demonstrated protective effects against cerebral ischemia. We analyzed the neuroprotective ability of oxyresveratrol using an in vitro model of stretch-induced trauma in co-cultures of neurons and glia, or by exposing cultures to high levels of glutamate. Cultures were treated with 25 µM, 50 µM or 100 µM oxyresveratrol at the time of injury. Trauma produced marked neuronal death when measured 24 h post-injury, and oxyresveratrol significantly inhibited this death. Microscopic examination of glia suggested signs of toxicity in cultures treated with 100 µM oxyresveratrol, as demonstrated by elevated S-100B protein release and a high proportion of cells with condensed nuclei. Cultures exposed to glutamate (100 µM) for 24 h exhibited ~ 37% neuronal loss, which was not inhibited by oxyresveratrol. These results show that the two pathologies of high glutamate exposure and trauma are differentially affected by oxyresveratrol treatment in vitro. Further studies using oxyresveratrol in trauma models are warranted, as toxicity to glia could be beneficial by inhibiting reactive gliosis, which often occurs after trauma.

The tryptophan depletion theory in delirium: not confirmed in elderly hip fracture patients.

BACKGROUND: The tryptophan depletion theory assumes that low tryptophan levels are present in delirium. These lower levels may be regarded as a biochemical marker for cellular immune activation, which may lead to increased catabolism of tryptophan into kynurenine via stimulation of the enzyme indoleamine 2,3-dioxygenase (IDO) by interferon-γ. OBJECTIVE: To compare plasma tryptophan and kynurenine levels, and IDO activity in hospitalized patients with and without delirium. METHODS: Repeated plasma samples were prospectively collected in hip fracture patients, aged 65 years and older. The presence of delirium was assessed daily. The associations of a delirious state and tryptophan, kynurenine, and the kynurenine/tryptophan ratio measured in samples taken 'before', 'during delirium', and 'after delirium' were analyzed with linear mixed models. RESULTS: A total of 469 samples from 140 patients were collected. Adjusted for the days on which they were drawn, there was no difference for all three measured factors in patients with and without delirium, except for an association between a higher kynurenine/tryptophan ratio and delirium in a subgroup analysis in preoperative samples. CONCLUSIONS: The results do not confirm the previously found lower tryptophan levels in delirium on which the tryptophan depletion theory is based. However, a preoperative higher kynurenine/tryptophan ratio could be indicative of delirium.

High preoperative plasma neopterin predicts delirium after cardiac surgery in older adults.

OBJECTIVES: To examine the association between plasma levels of pterins and amino acids and postoperative delirium. DESIGN: Prospective cohort study. SETTING: Cardiothoracic service in an university hospital in Rotterdam, the Netherlands. PARTICIPANTS: One hundred twenty-five individuals aged 70 and older undergoing elective cardiac surgery. MEASUREMENTS: Plasma pterins and amino acids were measured pre- and postoperatively. Using multiple logistic regression analyses, the associations between pterins and amino acid levels and postoperative delirium were examined in relation to age, sex, comorbidity, cognitive functioning (Mini-Mental State Examination (MMSE) score), and cardiac risk factors. RESULTS: Delirium incidence in the main study group was 31.3%. The preoperative measures associated with delirium were neopterin (odds ratio (OR) = 1.05, P = .009); MMSE score less than 28 (OR = 4.39, P = .001); European System for Cardiac Operative Risk Evaluation score greater than 6 (OR = 2.84, P = .03); and combined coronary artery bypass graft (CABG) and aortic, mitral, or tricuspid valve surgery (OR = 4.32, P = .01). Postoperative measures associated with delirium were neopterin (OR = 3.84, P = .02), homovanillic acid (HVA, OR = 1.01, P = .04), and preoperative MMSE score less than 28 (OR = 3.32, P = .008). CONCLUSION: Preoperatively high neopterin levels predicted delirium after cardiac surgery in older adults, in addition to the well-known risk factors of poor cognitive function, high cardio-surgical risk, and combined CABG and valve surgery. Postoperative neopterin and HVA levels were also found to be associated with delirium, together with preoperative cognitive functioning. Plasma neopterin may be a candidate biomarker for delirium after cardiac surgery in these older adults.

Serum brain-derived neurotrophic factor level in relation to illness severity and episode duration in patients with major depression.

BACKGROUND: Since there are few data on the possible association between BDNF levels and characteristics of major depression, the present study assesses brain-derived neurotrophic factor (BDNF) levels in three drug-free patient samples, and explores whether episode duration, and severity correlate with serum BDNF levels. METHOD: Serum BDNF levels were measured in 42 drug-free patients with major depression. The duration of the index episode and the presence of psychotic features were assessed with the Schedule for Affective Disorders and Schizophrenia, and the severity of depression was measured with the 17-item Hamilton Rating Scale for Depression. The sample was divided into three groups: severely depressed inpatients without psychotic features, severely depressed inpatients with psychotic features, and moderately depressed outpatients. RESULTS: Mean serum BDNF level in the total sample was 18.0 ± 2.8 ng/ml, with no significant difference between the three patient samples (F = 1.80, df = 2, p = 0.18). Mean serum BDNF level was significantly lower in patients with an index episode over one year, compared with patients who had a shorter index episode (F = 4.90, df = 1, p = 0.033). CONCLUSION: These data show that patients with a long index episode have significantly lower serum BDNF levels. We found no influence of the presence of psychotic features and severity of depression on serum BDNF levels.

Automated analysis of primary amino acids in plasma by high-performance liquid chromatography.

The concentration of primary amino acids (AAs) in plasma can accurately be determined using high-performance liquid chromatography (HPLC). Before the analysis can be performed, several steps have to be regarded. First, the time and method of blood withdrawal, type of blood tube, use of medication, and differences in dietary intake are important factors that should be standardized. Second, the handling of and the way the blood is transported to the laboratory, the time between blood withdrawal and centrifugation, the method of centrifugation, and the temperature and time of plasma storage have to be noticed. Third, the methods used for deproteinization and derivatization may account for varying results between laboratories.In this chapter, we describe an HPLC method that measures primary amino acids in plasma using automated precolumn derivatization with ortho-phthalaldehyde, and that pays attention to the above-mentioned criteria. This method is relatively fast, simple, sensitive, and reliable. Since with this method we can determine over 40 physiological amino acids with a very good resolution, trace amounts of amino acids can also be determined. In addition, interassay resolution times have very low variation and the use of two internal standards guarantees reliable quantification.

Mast cell degranulation mediates bronchoconstriction via serotonin and not via renin release.

To verify the recently proposed concept that mast cell-derived renin facilitates angiotensin II-induced bronchoconstriction bronchial rings from male Sprague-Dawley rats were mounted in Mulvany myographs, and exposed to the mast cell degranulator compound 48/80 (300 microg/ml), angiotensin I, angiotensin II, bradykinin or serotonin (5-hydroxytryptamine, 5-HT), in the absence or presence of the renin inhibitor aliskiren (10 micromol/l), the ACE inhibitor captopril (10 micromol/l), the angiotensin II type 1 (AT1) receptor blocker irbesartan (1 micromol/l), the mast cell stabilizer cromolyn (0.3 mmol/l), the 5-HT2A/2C receptor antagonist ketanserin (0.1 micromol/l) or the alpha1-adrenoceptor antagonist phentolamine (1 micromol/l). Bath fluid was collected to verify angiotensin generation. Bronchial tissue was homogenized to determine renin, angiotensinogen and serotonin content. Compound 48/80 contracted bronchi to 24+/-4% of the KCl-induced contraction. Ketanserin fully abolished this effect, while cromolyn reduced the contraction to 16+/-5%. Aliskiren, captopril, irbesartan and phentolamine did not affect this response, and the angiotensin I and II levels in the bath fluid after 48/80 exposure were below the detection limit. Angiotensin I and II equipotently contracted bronchi. Captopril shifted the angiotensin I curve approximately 10-fold to the right, whereas irbesartan fully blocked the effect of angiotensin II. Bradykinin-induced constriction was shifted approximately 100-fold to the left with captopril. Serotonin contracted bronchi, and ketanserin fully blocked this effect. Finally, bronchial tissue contained serotonin at micromolar levels, whereas renin and angiotensinogen were undetectable in this preparation. In conclusion, mast cell degranulation results in serotonin-induced bronchoconstriction, and is unlikely to involve renin-induced angiotensin generation.

Tryptophan depletion affects the autonomic stress response in generalized social anxiety disorder.

In generalized social anxiety disorder (gSAD), serotonergic dysfunctions are found, as well as abnormalities of the autonomic nervous system (ANS) in basal conditions and of the hypothalamic pituitary adrenal (HPA) axis in response to psychological challenges. These findings raise the question whether these phenomena are interrelated. Therefore we designed a study in which two groups with nine pair wise age and gender matched gSAD patients (total of 10 men and 8 women), who were successfully treated with a selective serotonin reuptake inhibitor (SSRI), underwent a tryptophan depletion challenge (TD) or a placebo condition. A TD procedure temporarily decreases serotonergic neurotransmission. In order to activate the stress system the TD/placebo challenge was combined with a public speaking task. We assessed ANS responses, as measured with the promising new marker salivary alpha-amylase (sAA), and HPA-axis responses, as measured with salivary cortisol. The most important result was that the TD group showed a significant larger sAA response to the public speaking task as compared to the placebo group, reflecting hyperresponsivity of the ANS in this group, whereas no differences were seen in cortisol responses. This suggests that in gSAD there is a vulnerability of the ANS more than the HPA-axis.