Human brain natriuretic peptide-like immunoreactivity in human brain

The Heart Is at Risk: Understanding Stroke-Heart-Brain Interactions with Focus on Neurogenic Stress Cardiomyopathy-A Review

In recent years, it has been convincingly demonstrated that acute brain injury may cause severe cardiac complications-such as neurogenic stress cardiomyopathy (NSC), a specific form of takotsubo cardiomyopathy. The pathophysiology of these brain-heart interactions is complex and involves sympathetic hyperactivity, activation of the hypothalamic-pituitary-adrenal axis, as well as immune and inflammatory pathways. There have been great strides in our understanding of the axis from the brain to the heart in patients with isolated acute brain injury and more specifically in patients with stroke. On the other hand, in patients with NSC, research has mainly focused on hemodynamic dysfunction due to arrhythmias, regional wall motion abnormality, or left ventricular hypokinesia that leads to impaired cerebral perfusion pressure. Comparatively little is known about the underlying secondary and delayed cerebral complications. The aim of the present review is to describe the stroke-heart-brain axis and highlight the main pathophysiological mechanisms leading to secondary and delayed cerebral injury in patients with concurrent hemorrhagic or ischemic stroke and NSC as well as to identify further areas of research that could potentially improve outcomes in this specific patient population.

Usefulness of B-Type Natriuretic Peptide for Predicting the Risk of Stroke in Patients With Heart Failure With Preserved Ejection Fraction

Background B-type natriuretic peptide (BNP) is a well-known biomarker for prognosis in heart failure with patients with preserved ejection fraction. However, the clinical predictive ability of BNP for the risk of stroke in HFpEF is not clear. Methods and Results A total of 799 patients with HFpEF from the TOPCAT (Treatment of Preserved Cardiac Function Heart Failure With an Aldosterone Antagonist) trial were included. Association of baseline BNP with risk of stroke was assessed using the Cox proportional hazard model. The discriminatory ability of BNP was expressed using the C index. The improvement in 5-year stroke prediction was assessed by C statistic, categorical net reclassification improvement index, and relative integrated discrimination improvement. A total of 34 (4.3%) patients among the 799 patients with HFpEF experienced stroke events over a median of 2.85 years of follow-up. The stroke group showed a higher BNP level than the nonstroke group (375 pg/mL versus 241 pg/mL, respectively; P=0.006). Higher BNP levels were associated with increased risk of stroke after multivariable adjustment (hazard ratio, 3.29 [95% CI, 1.51-7.16]) and had a moderate performance for stroke prediction (C index, 0.67). Adding BNP to CHADS₂/CHA₂DS₂-VASc/R₂CHADS₂ scores improved their predictive value for stroke (CHADS₂: C index, 0.67; BNP+CHADS₂: C index, 0.77; net reclassification improvement, 40.9%; integrated discrimination improvement, 3.0%; CHA₂DS₂-VASc: C index, 0.64; BNP+CHA₂DS₂-VASc: C index, 0.74; net reclassification improvement, 41.4%; integrated discrimination improvement, 2.2%; R₂CHADS₂: C index, 0.70; BNP+R₂CHADS₂: C index, 0.78; net reclassification improvement, 40.9%; integrated discrimination improvement, 3.2%). Conclusions BNP is associated with an increased risk of stroke in patients with HFpEF and may be a valuable biomarker for stroke prediction in HFpEF.

The Interplay between cGMP and Calcium Signaling in Alzheimer’s Disease

Cyclic guanosine monophosphate (cGMP) is a ubiquitous second messenger and a key molecule in many important signaling cascades in the body and brain, including phototransduction, olfaction, vasodilation, and functional hyperemia. Additionally, cGMP is involved in long-term potentiation (LTP), a cellular correlate of learning and memory, and recent studies have identified the cGMP-increasing drug Sildenafil as a potential risk modifier in Alzheimer’s disease (AD). AD development is accompanied by a net increase in the expression of nitric oxide (NO) synthases but a decreased activity of soluble guanylate cyclases, so the exact sign and extent of AD-mediated imbalance remain unclear. Moreover, human patients and mouse models of the disease present with entangled deregulation of both cGMP and Ca²⁺ signaling, e.g., causing changes in cGMP-mediated Ca²⁺ release from the intracellular stores as well as Ca²⁺-mediated cGMP production. Still, the mechanisms governing such interplay are poorly understood. Here, we review the recent data on mechanisms underlying the brain cGMP signaling and its interconnection with Ca²⁺ signaling. We also discuss the recent evidence stressing the importance of such interplay for normal brain function as well as in Alzheimer’s disease.

BNP and NT-proBNP Concentrations in Paired cerebrospinal Fluid and Plasma Samples of Patients with Traumatic Brain Injury

BACKGROUND

The aim of this study was to investigate the secretion patterns of brain natriuretic peptide (BNP) and N-terminal-proBNP (NT-proBNP) after traumatic brain injury (TBI) and to analyze the source of them in cerebrospinal fluid (CSF).

MATERIALS AND METHODS

We synchronously measured BNP and NT-proBNP concentrations in paired CSF and plasma samples from 22 moderate to severe TBI patients and 40 healthy control patients. The CSF and/or plasma ratio of albumin (Q_Albumin) was calculated daily. The BNP and NT-proBNP levels of CSF and plasma were compared between TBI patients and control patients.

RESULTS

CSF BNP and NT-proBNP levels peaked on day 3 after injury, as did the plasma BNP and NT-proBNP levels. The CSF BNP and NT-proBNP levels in TBI patients were elevated from day 1, which was significantly higher than control group (P < 0.05 and P < 0.01, respectively). However, in plasma, only NT-proBNP levels were significantly higher than in the control group from day 2 (P < 0.05). In addition, Q_BNP, defined as CSF BNP concentration and/or plasma BNP concentration, was significantly higher in TBI patients than in the control group (P < 0.01). However, Q_Albumin remained within ranges of a mild to moderate dysfunction of blood-brain-barrier in TBI patients.

CONCLUSIONS

CSF BNP concentrations are elevated and peak on day 3 after moderate to severe TBI. CSF BNP may originate from the brain and may be a potential biomarker of TBI.

Mechanism, spectrum, consequences and management of hyponatremia in tuberculous meningitis

Hyponatremia is the commonest electrolyte abnormality in hospitalized patients and is associated with poor outcome. Hyponatremia is categorized on the basis of serum sodium into severe (< 120 mEq/L), moderate (120-129 mEq/L) and mild (130-134mEq/L) groups. Serum sodium has an important role in maintaining serum osmolality, which is maintained by the action of antidiuretic hormone (ADH) secreted from the posterior pituitary, and natriuretic peptides such as atrial natriuretic peptide and brain natriuretic peptide. These peptides act on kidney tubules via the renin angiotensin aldosterone system. Hyponatremia <120mEq/L or a rapid decline in serum sodium can result in neurological manifestations, ranging from confusion to coma and seizure. Cerebral salt wasting (CSW) and syndrome of inappropriate secretion of ADH (SIADH) are important causes of hyponatremia in tuberculosis meningitis (TBM). CSW is more common than SIADH. The differentiation between CSW and SIADH is important because treatment of one may be detrimental for the other; evidence of hypovolemia in CSW and euvolemia or hypervolemia in SIADH is used for differentiation. In addition, evidence of dehydration, polyuria, negative fluid balance as assessed by intake output chart, weight loss, laboratory evidence and sometimes central venous pressure are helpful in the diagnosis of these disorders. Volume contraction in CSW may be more protracted than hyponatremia and may contribute to border zone infarctions in TBM. Hyponatremia should be promptly and carefully treated by saline and oral salt, while 3% saline should be used in severe hyponatremia with coma and seizure. In refractory patients with hyponatremia, fludrocortisone helps in early normalization of serum sodium without affecting polyuria or functional outcome. In SIADH, V2 receptor antagonist conivaptan or tolvaptan may be used if the patient is not responding to fluid restriction. Fluid restriction in SIADH has not been found to be beneficial in TBM and should be avoided.

Mechanism, spectrum, consequences and management of hyponatremia in tuberculous meningitis

Hyponatremia is the commonest electrolyte abnormality in hospitalized patients and is associated with poor outcome. Hyponatremia is categorized on the basis of serum sodium into severe (< 120 mEq/L), moderate (120-129 mEq/L) and mild (130-134mEq/L) groups. Serum sodium has an important role in maintaining serum osmolality, which is maintained by the action of antidiuretic hormone (ADH) secreted from the posterior pituitary, and natriuretic peptides such as atrial natriuretic peptide and brain natriuretic peptide. These peptides act on kidney tubules via the renin angiotensin aldosterone system. Hyponatremia <120mEq/L or a rapid decline in serum sodium can result in neurological manifestations, ranging from confusion to coma and seizure. Cerebral salt wasting (CSW) and syndrome of inappropriate secretion of ADH (SIADH) are important causes of hyponatremia in tuberculosis meningitis (TBM). CSW is more common than SIADH. The differentiation between CSW and SIADH is important because treatment of one may be detrimental for the other; evidence of hypovolemia in CSW and euvolemia or hypervolemia in SIADH is used for differentiation. In addition, evidence of dehydration, polyuria, negative fluid balance as assessed by intake output chart, weight loss, laboratory evidence and sometimes central venous pressure are helpful in the diagnosis of these disorders. Volume contraction in CSW may be more protracted than hyponatremia and may contribute to border zone infarctions in TBM. Hyponatremia should be promptly and carefully treated by saline and oral salt, while 3% saline should be used in severe hyponatremia with coma and seizure. In refractory patients with hyponatremia, fludrocortisone helps in early normalization of serum sodium without affecting polyuria or functional outcome. In SIADH, V2 receptor antagonist conivaptan or tolvaptan may be used if the patient is not responding to fluid restriction. Fluid restriction in SIADH has not been found to be beneficial in TBM and should be avoided.

Analysis of Brain Natriuretic Peptide Serum Levels in Patients with Symptomatic Chronic Subdural Hematoma: A Potential Reliable Biomarker

The purpose of this study was to analyze brain natriuretic peptide (BNP) serum levels of patients with chronic subdural hematoma (cSDH) and their clinical implication. Patients with cSDH who underwent surgery in our department between November 2016 and October 2019 were eligible for enrollment in the study. Patients with recurrent bleedings, traumatic brain injury, cSDH associated with other intracranial pathologies, and those with a history of congestive heart failure, renal or endocrine disease were excluded. We measured BNP serum levels pre- and post-operatively and at discharge. The BNP values were analyzed with respect to patient medical history and neurological condition. The Glasgow Coma Scale score and the modified Rankin Scale score classified the clinical and neurological condition at the time of admission and discharge, respectively. The data of 100 surgically treated patients with cSDH (mean age 73.2, range 42 − 94 years, male/female 3.5:1) were analyzed. Pre-operative BNP serum levels (BNP-1) were elevated in 67% of the patients (n = 67; median = 101.6 pg/mL; p < 0.001). These serum levels increased after surgery (p < 0.001) and decreased thereafter (p < 0.001), reaching a level at discharge (day 7) that was not statistically different from BNP-1 (p > 0.05). In addition, elevated BNP-1 showed a significant statistical association with the presence of atrial fibrillation (p < 0.01) and antiplatelet and/or anticoagulant therapy (p < 0.01). This study provides new evidence regarding BNP serum levels and their secretion pattern in patients with cSDH. Whether BNP-1 can predict the long-term functional outcome of patients with cSDH is being investigated in this ongoing prospective study.

The Relationships Between BNP and Neurocardiac Injury Severity, Noninvasive Cardiac Output, and Outcomes After Aneurysmal Subarachnoid Hemorrhage

INTRODUCTION

Neurocardiac injury, a type of myocardial dysfunction associated with neurological insult to the brain, occurs in 31-48% of aneurysmal subarachnoid hemorrhage (aSAH) patients. Cardiac troponin I (cTnI) is commonly used to diagnose neurocardiac injury. Brain natriuretic peptide (BNP), another cardiac marker, is more often used to evaluate degree of heart failure. The purpose of this study was to examine the relationships between BNP and (a) neurocardiac injury severity according to cTnI, (b) noninvasive continuous cardiac output (NCCO), and (c) outcomes in aSAH patients.

METHOD

This descriptive longitudinal study enrolled 30 adult aSAH patients. Data collected included BNP and cTnI levels and NCCO parameters for 14 days and outcomes (modified Rankin Scale [mRS] and mortality) at discharge and 3 months. Generalized estimating equations were used to evaluate associations between BNP and cTnI, NCCO, and outcomes.

RESULTS

BNP was significantly associated with cTnI. For every 1 unit increase in log BNP, cTnI increased by 0.05 ng/ml ( p = .001). Among NCCO parameters, BNP was significantly associated with thoracic fluid content ( p = .0003). On multivariable analyses, significant associations were found between BNP and poor mRS. For every 1 unit increase in log BNP, patients were 3.16 times more likely to have a poor mRS at discharge ( p = .021) and 5.40 times more likely at 3 months ( p < .0001).

CONCLUSION

There were significant relationships between BNP and cTnI and poor outcomes after aSAH. BNP may have utility as a marker of neurocardiac injury and outcomes after aSAH.

Exophytic bulbar pilocytic astrocytoma and post-operative cerebral salt wasting syndrome

Cerebral salt wasting syndrome (CSWS) is a well-described consequence of several neurological disorders. Although the exact etiology of CSWS is still not completely elucidated, it is believed that the hypothalamus plays a pivotal role in the genesis of this disorder. We report for the first time 3 cases of CSWS occurring during the post-operative course following surgical resection of exophytic bulbar pilocytic astrocytomas in children. Since these 3 cases shared in common a medial implication of the medulla, we suggest that specific interconnectivity between the dorso-medial portion of the medulla oblongata and the hypothalamus might thus represent an anatomical pathway of interest in the pathogenesis of CSWS. Our findings suggest that the resection of medially located exophytic bulbar tumors might constitutes a risk factor in the development of CSWS. Particular care should thus be carried towards the prompt detection and treatment of CSWS in the post-operative courses of exophytic bulbar tumors.

Role of brain natriuretic peptide as a novel prognostic biomarker in acute ischemic stroke

Aim:

We investigated to study the prognostic importance of brain natriuretic peptide (BNP) in ischemic stroke.

Materials and Methods:

We prospectively enrolled 100 patients with acute ischemic stroke and measured plasma BNP levels and compared with age- and sex-matched healthy controls. Risk factors, biochemical parameters, lipid profile, carotid and vertebral Doppler, imaging, and cardiac evaluation were done. Stroke severity was assessed by the National Institutes of Health Stroke Scale (NIHSS) score on admission and functional disability by Barthel Index (BI) at 3 months. Ischemic stroke subtype was classified according to the Oxfordshire Community Stroke Project (OCSP). Data were entered in MS Excel, and appropriate statistical analysis was done using the SPSS software version 21.0. A P = 0.05 was considered as significant.

Results:

Mean age of patients was 55.17 ± 11.37 years with a male:female ratio 3:1. OCSP showed total anterior circulation infarct (TACI) 35, partial anterior circulation infarct 9, lacunar infarct 12, and posterior circulation infarct 44. NIHSS on admission was average 10 ± 7 and BI was 57 ± 30. BNP in patients (435 ng/ml) was very high as compared to controls (<60 ng/ml) (P < 0.001). There was a positive correlation between age and BNP (R² = 0.34; P < 0.00); NIHSS and BNP (R² = 0.255; P < 0.01), negative correlation between BI and BNP (R² = −0.064; P < 0.01). Mean BNP levels across the OCSP showed higher values in TACI (F = 4.609 P = 0.005). Regression analysis showed that BNP can predict BI which was statistically significant.

Conclusion:

Plasma BNP levels was significantly elevated in patients with ischemic stroke. Our study concludes that high BNP levels are seen in large anterior circulation stroke and is a predictor for the poor functional outcome at 3 months. Determination of BNP levels as a biomarker could be helpful in predicting the outcome in stroke patients.

Natriuretic peptides in the central nervous system: Novel targets for cognitive impairment

Natriuretic peptides (NPs) are traditionally known as cardiac hormones with diuretic, natriuretic and blood pressure lowering properties. Evidence indicates that NPs and their receptors are abundant in the central nervous system, suggesting their involvement in regulation of various brain functions. It has been shown that NPs are involved in the regulation of neurovascular and blood-brain barrier integrity, neuro-inflammation, neuroprotection, synaptic transmission and brain fluid homeostasis. In addition, NPs might contribute to the brain's inhibitory control over the hypothalamic-pituitary-adrenal axis. Studies have also shown that high systemic levels of NPs are associated with cognitive impairment independent of cardiovascular risk factors. In this review we discuss the potential roles of NPs in regulating structural and functional integrity of the brain. Based on the available neurobiological and clinical evidence, we propose that NPs might represent as potential novel diagnostic and therapeutic targets for cognitive impairment.

Levels of brain natriuretic peptide as a marker for the diagnosis and prognosis of acute ischemic stroke

Introduction

The relationships between plasma levels of brain natriuretic peptide (BNP) and severity and location of stroke, prognosis, and infarct volume were investigated in acute ischemic stroke patients who presented within the first 24 hours (h) of stroke.

Material and methods

Brain natriuretic peptide levels were tested in 40 patients and 30 healthy controls. Infarct volume was automatically calculated by multi-slice computed tomography. Disease severity was assessed using the National Institutes of Health Stroke Scale (NIHSS) at presentation, 24 h, 72 h and the 28^th day. Progression was defined as an increase of more than two points in the NIHSS scores.

Results

The mean BNP levels were 284.16 ±382.79 at presentation and 273.78 ±451.91 at 72 h in the patient group, whereas the mean BNP level was 25.29 ±13.47 in controls. There was a statistically significant difference between the two groups (p < 0.001). Differences in BNP levels among patient subgroups according to the TOAST and OCSP classifications were not statistically significant (p = 0.534, p = 0.943, respectively). There was no significant correlation between plasma BNP level and infarct volume or NIHSS scores (p = 0.5, p = 0.07). A positive correlation was found between BNP levels and the length of the hospitalization period (p = 0.03 and r = 0.33). There was no statistically significant relationship between elevated plasma BNP levels and progression of disease (p = 0.08).

Conclusions

Plasma BNP levels were increased in the acute phase of stroke; therefore, BNP could be used as a biomarker for morbidity and mortality, even in patients without cardiac failure.

Ubiquitous expression and multiple functions of biologically active peptides

Biologically active peptides are widely expressed throughout in human bodies. For example, endothelin-1 and adrenomedullin are expressed in almost all types of cells, including neurons, glial cells, fibroblasts, macrophages, cardiomyocytes, vascular endothelial cells, epithelial cells and cancer cells of various origins. Expression of both these peptides is induced by stimuli, such as hypoxia and inflammatory cytokines. They have a variety of biological functions, such as effects on brain function, hormone secretion, the cardiovascular system and cell proliferation. By contrast, orexins (hypocretins) and melanin-concentrating hormone (MCH) are specifically expressed in the hypothalamus, particularly in the lateral hypothalamus, although very low concentrations of these peptides are found in the peripheral tissues. Orexins and MCH play coordinated, but distinct physiological roles in the regulation of sleep-wake cycle, appetite, emotion and other brain functions. The cardiovascular system is regulated by cardiovascular peptides, such as natriuretic peptides, endothelins and angiotensin II. The renin-angiotensin system (RAS) is one of the most classical regulatory systems on blood pressure, electrolytes and kidney. (Pro)renin receptor is a novel member of the RAS and may be related to the pathophysiology of microvascular complications of hypertension and diabetes mellitus. Moreover, (pro)renin receptor forms a functional complex with vacuolar-type H(+)-ATPase, which plays an important physiological role in maintaining the acidic environment of intracellular compartments including secretory vesicles. Perhaps, the complex of (pro)renin receptor and vacuolar-type H(+)-ATPase may be important for the post-translational processing and secretion of many biologically active peptides.

Predictors of increased cumulative serum levels of the N-terminal prohormone of brain natriuretic peptide 4 days after acute spontaneous subarachnoid hemorrhage

Object

The rupture of an intracranial aneurysm is followed by increased intracranial pressure and decreased cerebral blood flow. A major systemic stress reaction follows, presumably to restore cerebral blood flow. However, this reaction can also cause adverse effects, including myocardial abnormalities, which are common and can be serious, and increased levels of natriuretic peptides, especially brain natriuretic peptide (BNP). The association of BNP with fluid and salt balance, vasospasm, brain ischemia, and cardiac injury has been studied but almost exclusively regarding events after admission. Brain natriuretic peptide has also been measured at various time points and analyzed in different ways statistically. The authors approached BNP measurement in a new way; they used the calculated area under the curve (AUC) for the first 4 days to quantitatively measure the BNP load during the first critical part of the disease state. Their rationale was a suspicion that early BNP load is a marker of the severity of the ictus and will influence the subsequent course of the disease by disturbing the fluid and salt balance.

Methods

The study included 156 patients with acute spontaneous subarachnoid hemorrhage (SAH). Mean patient age was 59.8 ± 11.2 years, and 105 (67%) of the patients were female. An aneurysm was found in 138 patients. A total of 82 aneurysms were treated by endovascular coiling, 50 were treated by surgery, and 6 were untreated. At the time of admission, serum samples were collected for troponin-I analysis and for the N-terminal prohormone of BNP (NT-proBNP); daily thereafter, samples were collected for the NT-proBNP analysis. The cumulative BNP load was calculated as the AUC for NT-proBNP during the first 4 days. The following variables were studied in terms of their influence on the AUC for NT-proBNP: sex, age, World Federation of Neurosurgical Societies grade of SAH, Fisher grade, angiographic result, treatment of aneurysm, clinical neurological deterioration, verified infections, vasospasm treatment, and 6-month outcome.

Results

The AUC for NT-proBNP was larger when variables indicated a more severe SAH. These variables were higher Fisher and World Federation of Neurosurgical Societies grades, high levels of troponin-I at admission, an aneurysm, neurological deficits, and infections. The AUC for NT-proBNP was also larger among women, older patients, and patients with poor outcomes. Linear regression showed that the best predicting model for large AUC for NT-proBNP was the combination of the following: female sex, high levels of troponin-I, an aneurysm, neurological deficits, and advanced age.

Conclusions

The cumulative BNP load during the first days after SAH can be predicted by variables describing the severity of the disease already known at the time of admission. This information can be used to identify patients at risk for an adverse course of the disease.

Phage display generation of a novel humanized single-chain antibody against brain natriuretic peptide with potent neutralizing activity

Cerebral salt wasting syndrome (CSW) is defined as a renal loss of sodium and water during intracranial disease leading to hyponatremia, which is the most frequent electrolyte disorder in critically neurological patients. Abnormal brain natriuretic peptide (BNP) secretion is implicated as the main offender. Development of antagonist against BNP is therefore of potential clinical relevance. In this study, synthetic human BNP peptide (hBNP) was used as bait and a humanized single chain fragment variable (scFv) phage antibody library as the source of antagonists. After three rounds of biopanning, hBNP-specific phage clones were greatly enriched. The scFv gene from the best phage clone was inserted into pET-22b and expressed in Escherichia coli BL21 (DE3) PlysS cells. After purification by nickel-affinity and refolding, this scFv antibody (Ab) was proven to recognize hBNP specifically and sensitively in ELISA and dot-blotting assay. Its binding constant to hBNP was 1.98×10(-8) M, measured by surface plasmon resonance. Thus, the humanized scFv Ab prepared with this approach has potential therapeutic value for neutralizing abnormally high level of BNP correlated well with CSW.

Potent and direct presynaptic modulation of glycinergic transmission in rat spinal neurons by atrial natriuretic peptide

Atrial and brain natriuretic peptides (ANP and BNP) exist in the central nervous system and modulate neuronal function, although the locus of actions and physiological mechanisms are still unclear. In the present study we used rat spinal sacral dorsal commissural nucleus (SDCN) and hippocampal 'synaptic bouton' preparations, to record both spontaneous and evoked glycinergic inhibitory postsynaptic currents (sIPSCs and eIPSCs) in SDCN neurons, and the evoked excitatory postsynaptic currents (eEPSCs) in hippocampal CA3 neurons. ANP potently and significantly reduced the sIPSC frequency without affecting the amplitude. ANP also potently reduced the eIPSCs amplitude concurrently increasing the failure rate and the paired pulse ratio response. These ANP actions were blocked by anantin, a specific type A natriuretic peptide receptor (NPR-A) antagonist. The results clearly indicate that ANP acts directly on glycinergic presynaptic nerve terminals to inhibit glycine release via presynaptic NPR-A. The ANP effects were not blocked by the membrane permeable cGMP analog (8Br-cGMP) suggesting a transduction mechanisms not simply related to increasing cGMP levels in nerve terminals. BNP did not affect on glycinergic sIPSCs and eIPSCs. Moreover, both ANP and BNP had no effect on glutamatergic EPSCs in hippocampal CA3 neurons. The results indicate a potent and selective presynaptic inhibitory action of ANP on glycinergic transmission in spinal cord sensory circuits.

Elevated troponin level with negative outcome was found in ischemic stroke

Background. Troponin increment is a highly sensitive and specific marker of myocardial necrosis. The reason of high troponin levels in acute stroke is not clear. The aim of this study was to identify the relationships between cardiac troponin-I (cTnI) level and stroke. Methods. This study recruited 868 patients who were admitted to Istanbul Medeniyet University due to acute ischemic stroke, and the diagnosis was confirmed by diffusion magnetic resonance imaging. The patients with the causes increasing troponin level were excluded from the study. A total of 239 patients were finally included in the study. Clinics were evaluated by the modified Rankin Scale (mRS) and the National Institutes of Health Stroke Scale (NIHSS). Results. Serum level of troponin was higher in ischemic stroke patients with anterior circulation involvement in comparison to posterior involvement or hemorrhagic stroke (P < 0.05). Higher troponin levels related to increased stroke scale scores at discharge in ischemic stroke (P < 0.05). The level of cTnI was correlated with stroke scale scores at both admission and discharge in posterior stroke patients (P < 0.01). Conclusion. cTnI is a highly specific and sensitive marker of myocardial damage, and its elevation was associated with more severe neurological deficits in acute ischemic stroke.

Hyponatremia associated with demyelinating disease of the nervous system

A 63-year-old man was diagnosed with periodontitis and underwent tooth extraction. Several days later, he suffered a high fever, ischuria, a change in personality, and disorientation. A urologist examined him and found severe hyponatremia (117 mEq/L), and he was then transferred to our hospital. On admission, physical findings revealed dysfunction of the bladder and bowel, altered mental status, and hypovolemia. Blood chemistry showed serum sodium of 120 mEq/L, a serum urate of 1.4 mg/dL, urinary Na of 61 mEq/L, and fractional urate excretion of 16 %. Examination of the cerebrospinal fluid (CSF) showed monocytosis. Magnetic resonance imaging (MRI) of the brain and spinal cord showed multiple lesions characterized by hyperintensity on T2-weighted sequences, suggesting demyelinating disease. His sodium concentration normalized 3 days after volume replacement therapy, and his altered mental status along with the dysfunction of the bladder and bowel were promptly improved after the initiation of high-dose glucocorticoids. Additionally, the abnormal lesions on MRI markedly decreased. This clinical course led to the likely diagnosis of acute disseminated encephalomyelitis (ADEM). Hyponatremia in neurologically injured patients is usually attributed to the syndrome of inappropriate antidiuretic hormone (SIADH) or cerebral salt-wasting syndrome (CSWS). In the present patient, the uric acid level remained low and uric acid excretion remained elevated despite correction of the hyponatremia, which suggested CSWS. The differentiation of CSWS from SIADH is difficult but critically important due to the fact that the disorders are managed differently. Coexistence of ADEM and CSWS has rarely been reported.

Plasma NT-proBNP and white matter hyperintensities in type 2 diabetic patients

Abstract

Elevated plasma N-terminal (NT)-proBNP from the heart as well as white matter hyperintensities (WMH) in the brain predict cardiovascular (CV) mortality in the general population. The cause of poor prognosis associated with elevated P-NT-proBNP is not known but WMH precede strokes in high risk populations. We assessed the association between P-NT-proBNP and WMH or brain atrophy measured with magnetic resonance imaging (MRI) in type 2 diabetic patients, and age-matched controls.

Methods and results

We measured P-NT-proBNP(ng/l) in 20 diabetic patients without prior stroke but with(n = 10) or without(n = 10) asymptomatic coronary artery disease(CAD) in order to include patients with a wide-ranging CV risk profile. All patients and 26 controls had a 3D MRI and brain volumes(ml) with WMH and brain parenchymal fraction(BPF), an indicator of brain atrophy, were determined.

P-NT-proBNP was associated with WMH in linear regression analysis adjusted for CV risk factors(r = 0.94, p = 0.001) and with BPF in univariate analysis(r = 0.57, p = 0.009). Patients divided into groups of increased P-NT-proBNP levels were paralleled with increased WMH volumes(geometric mean[SD];(2.86[5.11] ml and 0.76[2.49] ml compared to patients with low P-NT-proBNP 0.20[2.28] ml, p = 0.003)) and also when adjusted for age, sex and presence of CAD(p = 0.017). The association was strengthened by CV risk factors and we did not find a common heart or brain specific driver of both P-NT-proBNP and WMH. Patients and particular patients with CAD had higher WMH, however no longer after adjustment for age and sex.

Conclusion

P-NT-proBNP was associated with WMH in type 2 diabetic patients, suggesting a linkage between heart and brain disease.

Expression of kisspeptins and kisspeptin receptor in the kidney of chronic renal failure rats

Kisspeptins are biologically active cleavage peptides of the KiSS-1 gene products with important roles in the suppression of tumor metastasis and in the reproduction. The aim of the present study is to clarify changes of the expression of kisspeptins and kisspeptin receptor in the kidney with and without chronic renal impairment. 5/6 nephrectomized rats were used as the rat model of chronic renal failure. Competitive quantitative RT-PCR showed that kisspeptin mRNA levels were decreased in the kidney of 5/6 nephrectomized rats at 56 days compared with sham-operated rats. In contrast, immunoreactive kisspeptin concentrations were increased in the kidney of 5/6 nephrectomized rats at 56 days. On the other hand, kisspeptin receptor mRNA levels were increased in the kidney of 5/6 nephrectomized rats at 14 and 56 days compared with sham-operated rats. Immunocytochemistry showed that kisspeptins and kisspeptin receptor were expressed in renal tubular cells, collecting duct cells, vascular smooth muscle cells in both rats. The intensity of kisspeptin receptor immunostaining was lower in 5/6 nephrectomized rats than in sham-operated rats. Western blot analysis confirmed that kisspeptin receptor protein levels were significantly decreased in the remnant kidney of 5/6 nephrectomized rats (about 23% of sham-operated rats), which is a good contrast to the kisspeptin receptor mRNA expression. The present study has shown that expression of kisspeptins and kisspeptin receptor are altered in the kidney tissues of chronic renal impairment, raising the possibility of their pathophysiological roles in chronic renal failure.

Cerebral salt wasting: pathophysiology, diagnosis, and treatment

Cerebral salt wasting (CSW) is a syndrome of hypovolemic hyponatremia caused by natriuresis and diuresis. The mechanisms underlying CSW have not been precisely delineated, although existing evidence strongly implicates abnormal elevations in circulating natriuretic peptides. The key in diagnosis of CSW lies in distinguishing it from the more common syndrome of inappropriate secretion of antidiuretic hormone. Volume status, but not serum and urine electrolytes and osmolality, is crucial for making this distinction. Volume and sodium repletion are the goals of treatment of patients with CSW, and this can be performed using some combination of isotonic saline, hypertonic saline, and mineralocorticoids.

Expression of adrenomedullin 2/intermedin, a possible reno-protective peptide, is decreased in the kidneys of rats with hypertension or renal failure

Adrenomedullin 2/intermedin (AM2/IMD) is a potent vasodilator peptide with organ-protective effects and is abundantly expressed in the kidney. We examined the expression of AM2/IMD in the kidneys of rats with hypertension or chronic renal impairment using quantitative RT-PCR, radioimmunoassay, and immunohistochemistry. Kidneys of 8-wk-old male spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats were dissected into inner medulla, outer medulla, cortex, and glomerulus fractions. A rat renal impairment model was prepared by 5/6 nephrectomy in WKY rats. AM2/IMD mRNA levels were the highest in the cortex among four renal portions, and significantly lower in SHR than WKY rats in all renal portions. In the remnant kidneys of 5/6 nephrectomized rats, AM2/IMD mRNA levels were significantly decreased on days 3 and 56, whereas mRNA levels of calcitonin receptor-like receptor, receptor activity-modifying proteins-1 and -2, which form receptor for AM and AM2/IMD, were increased, compared with that in sham-operated rats. AM mRNA levels were decreased on day 3, but increased on day 56, after nephrectomy. Decreased immunoreactive AM2/IMD levels in the remnant kidneys of 5/6 nephrectomized rats on day 56 were confirmed by radioimmunoassay. The renal tubules were immunostained with anti-AM2/IMD antibody, with a decreased AM2/IMD immunostaining found in proximal tubular cells of 5/6 nephrectomized rats compared with sham-operated rats. In conclusion, intrarenal AM2/IMD expression is decreased in SHR and 5/6 nephrectomized rats. Given the organ-protective effects of AM2/IMD, the downregulation of AM2/IMD as an endogenous regulatory peptide may have a role in the progression of renal impairment.

Epilepsy and hormones: a critical review

Especially during growth, puberty, and menopause, profound changes including maturation of the growth hormone, sex steroid, and thyroid axes, as well as alterations in lipid homeostasis, cardiac integrity, and other enzyme systems, occur physiologically. With epilepsy, however, things are often changing, and there may be a complicated interplay between hormones, epilepsy, and antiepileptic drugs (AEDs). On the one hand, epilepsy itself possibly elicits diverse effects on different enzyme systems including sex steroids, the neuro-cardio-endocrine axis, and bone health. On the other hand, different AEDs are known to induce neuroendocrine changes (e.g., lipid metabolism) that may have deleterious consequences on health and well-being later in life. It is important for physicians and epileptologists to have in mind and to consider the endocrine effects induced by epilepsy itself or by a certain AED when starting antiepileptic therapy, especially when it is expected that long-term treatment will be necessary.

Expression of peptide YY in human brain and pituitary tissues

Expression of peptide YY (PYY) in the human brain and pituitary tissues was studied by radioimmunoassay, immunocytochemistry, and reverse transcription polymerase chain reaction. The polyclonal antibody raised against human PYY(1-36) in a rabbit was used in the assay, which showed 100% cross-reactivity with PYY(3-36) and no significant cross-reactivity with other peptides including neuropeptide Y and pancreatic polypeptide. The highest concentration of immunoreactive PYY was found in the hypothalamus (0.44+/-0.060 pmol/g of wet weight, mean +/- SEM, n=8), followed by the pituitary (0.41+/-0.16 pmol/g of wet weight, n=3). Reverse-phase high performance liquid chromatography of tissue extracts of human rectum and cortical brain showed a peak eluted in the position of authentic PYY(1-36) and PYY(3-36). Immunocytochemistry showed positive immunostaining for PYY in neurons of the paraventricular, arcuate, and supraoptic nuclei of the human hypothalamus. Moreover, reverse transcription polymerase chain reaction analysis showed expression of mRNA for PYY in human brain and pituitary tissues. The present study has shown for the first time expression of PYY in the human brain and pituitary tissues, suggesting a role for PYY as a neurotransmitter, in the neuroendocrine physiology, such as regulation of appetite and energy expenditure and modulation of pituitary hormone secretion.

Cardiac troponin T elevation after stroke: relationships between elevated serum troponin T, stroke location, and prognosis

Background and Purpose

Elevation of serum cardiac troponin T (cTnT) is regarded as a specific marker of acute coronary syndrome. Serum cTnT can be increased in patients with acute ischemic stroke, but its clinical implications remain unclear. The aim of this study was to identify the relationships between elevated cTnT and stroke severity, location, and prognosis.

Methods

From January 2005 to December 2006, this study recruited 455 consecutive patients who were admitted to Kangbuk Samsung Hospital due to acute ischemic stroke within 3 days of onset, which was confirmed by diffusion magnetic resonance imaging. A total of 416 patients was finally included and divided into 2 groups: an elevated cTnT group (n=45) and a normal cTnT group (n=371). The short-term prognosis was assessed by 30-day modified Rankin Scale responder analysis was compared between the two groups.

Results

Serum cTnT was elevated in 10.8% of cases, with elevated cTnT associated with greater stroke severity, as assessed by the National Institutes of Health Stroke Scale score, Insular-lobe involvement was more common in patients with elevated cTnT than in the normal cTnT group. Short-term prognosis was more unfavorable in the elevated cTnT group than in the normal cTnT group. Multivariate regression analysis indicated that elevated cTnT was independently related to insular involvement, cardioembolism, and unfavorable outcome.

Conclusions

Elevated cTnT in acute ischemic stroke was associated with severe neurological deficits at stroke onset and damages to the insular lobe. The outcome of acute ischemic stroke was worse for patients with elevated cTnT than for those with normal cTnT. The pathomechanism underlying acute ischemic stroke and subclinical myocardial damage warrants further study.

Cerebral salt wasting syndrome: review

Hyponatremia is the most frequent electrolyte disorder in critically neurological patients. Cerebral salt wasting syndrome (CSW) is defined as a renal loss of sodium during intracranial disease leading to hyponatremia and a decrease in extracellular fluid volume. The pathogenesis of this disorder is still not completely understood. Sympathetic responses as well as some natriuretic factors play a role in this syndrome. Distinction between SIADH and CSW might be difficult. The essential point is the volemic state. It is necessary to rule out other intermediate causes. Treatment requires volume replacement and maintenance of a positive salt balance. Mineral corticoids may be useful in complicated cases.

Natriuretic peptides and their receptors in the central nervous system

Natriuretic peptides (NPs), including atrial, brain and C-type NPs, are a family of structurally related but genetically distinct peptides. These peptides, along with their receptors (NPRs), are long known to be involved in the regulation of various physiological functions, such as diuresis, natriuresis, and blood flow. Recently, abundant evidence shows that NPs and NPRs are widely distributed in the central nervous system (CNS), suggesting possible roles of NPs in modulating physiological functions of the CNS. This review starts with a brief summary of relevant background information, such as molecular structures of NPs and NPRs and general intracellular mechanisms after activation of NPRs. We then provide a detailed description of the expression profiles of NPs and NPRs in the CNS and an in-depth discussion of how NPs are involved in neural development, neurotransmitter release, synaptic transmission and neuroprotection through activation of NPRs.

Determinants of plasma levels of brain natriuretic peptide after acute ischemic stroke or TIA

Plasma levels of brain natriuretic peptide (BNP) are frequently elevated after an acute stroke and have been shown to be an independent predictor of mortality. However, the relationships between stroke and BNP concentrations have not yet been systematically investigated. Plasma BNP assay and echocardiography were performed in 48 patients with ischemic stroke or TIA with a mean delay of 12.7 h after onset. Median BNP concentration was 88.6 pg/mL (range 5-1270). Older age, chronic heart failure, atrial fibrillation, stroke severity, lower hemoglobin levels, lower left ventricular ejection fraction, and abnormalities of left atrium or appendage (LA/LAA) were univariately associated with increased BNP levels. At multivariable analysis, the presence of at least one LA/LAA abnormality (atrial dilatation, low flow velocity, spontaneous echocontrast or thrombus) had the strongest association with BNP, explaining 38.9% of the variance in the whole sample and 28.5% in patients without atrial fibrillation. In acute ischemic stroke patients, elevated plasma BNP levels have multiple determinants, among which left atrial disease appears to be the stronger, even in patients without atrial fibrillation. These results encourage further investigation of plasma BNP concentration as a potential marker of the presence of left atrial sources of emboli.

Hyponatremia and Comparison of NT-pro-BNP Concentrations in Blood Samples from Jugular Bulb and Arterial Sites after Traumatic Brain Injury in Adults: A Pilot Study

BACKGROUND

Hyponatremia after traumatic brain injury (TBI) may influence neurological function and treatment. A causal relationship between elevated serum concentrations of Type B natriuretic peptide (BNP) and hyponatremia has been implied after subarachnoid hemorrhage and other neurosurgical disorders, although the source of BNP has not been identified. We evaluated if hyponatremia and increased BNP occur after TBI and if BNP is produced/released by the brain within 24 h after injury.

RESULTS

NT-proBNP was measured in concomitant jugular venous and arterial blood samples within 24 h after TBI. NT-proBNP was elevated in both samples in six patients (24%). One patient (4%) showed an increased jugular NT-proBNP concentration above a normal arterial concentration, suggesting a brain source. In the other 24 patients the difference between jugular and arterial NT-proBNP was not statistically significant. Hyponatremia (< or =136 mEq/l) also occurred in six patients (24%), but only two (8%) had both increased arterial NT-proBNP and hyponatremia. In both the urine sodium was slightly elevated above normal, but not statistically different from other patients. The difference in serum sodium between hypo- and normo-natremic groups was significant, but mean NT-proBNP and jugular:arterial NT-proBNP differences were not.

CONCLUSIONS

In this pilot study BNP is elevated within 24 h after TBI in some patients. However, it does not originate from the brain and increased NT-proBNP concentrations are not consistently associated with hyponatremia or increased urinary sodium loss.

B-type natriuretic peptide as a marker for heart failure in patients with acute stroke

OBJECTIVE

To determine whether serum N-terminal pro-B-type natriuretic peptide (N-BNP), a biomarker of myocardial wall stress, is specific to acute heart failure (HF) in patients hospitalized with stroke.

DESIGN

Case-control study.

SETTING

Tertiary hospital, Neurosciences Critical Care Unit and Stroke Unit.

PATIENTS

Consecutive patients with acute ischemic or hemorrhagic stroke who were evaluated for HF.

INTERVENTION

None.

MEASUREMENTS AND RESULTS

Cases and controls were classified, respectively, as patients with or without HF, defined according to modified Framingham criteria. Seventy-two patients were evaluated, 39 with ischemic stroke, 22 with aneurysmal subarachnoid hemorrhage (SAH), and 11 with intracerebral hemorrhage (ICH). Thirty-four patients (47%) met criteria for HF, and 47 patients (65%) had systolic or diastolic left ventricular (LV) dysfunction on echocardiogram. Serum N-BNP was measured a median of 48 h following the onset of stroke and was increased (> 900 pg/ml) in 56 patients (78%), with higher levels in non-survivors (11898 +/- 12741 vs 4073 +/-5691; p = 0.001). In a multiple regression model, N-BNP elevation was not independently associated with HF (OR 5.4, 95% CI 0.8-36.0, p = 0.084). At a cut-off of 900 pg/ml, the sensitivity of N-BNP for HF was 94%, specificity 37%, positive predictive value (PPV) 57%, and negative predictive value (NPV) 88%. For systolic or diastolic LV dysfunction, the sensitivity of N-BNP was 89%, specificity 44%, PPV 75%, and NPV 69%.

CONCLUSIONS

These results demonstrate that N-BNP elevation is not specific to HF or LV dysfunction in patients with acute ischemic stroke, SAH, and ICH.

Expression of adrenomedullin2/intermedin in human brain, heart, and kidney

Adrenomedullin2/intermedin (AM2/IMD) is a novel member of the calcitonin/calcitonin gene-related peptide (CGRP) family. In the present study, we developed a specific radioimmunoassay of human AM2/IMD. Expression of AM2/IMD was studied in the human brain, pituitary, heart and kidney obtained at autopsy by radioimmunoassay and immunocytochemistry. Immunoreactive-AM2/IMD was detected by radioimmunoassay in human brains (range; 0.163-1.495 pmol/g wet weight), pituitaries (4.46+/-0.689 pmol/g wet weight, mean+/-S.E.M, n=3), left ventricles of hearts (0.251+/-0.0321 pmol/g wet weight, n=4), kidneys (3.49+/-1.18 pmol/g wet weight, n=5), and plasma obtained at healthy subjects (24.7+/-1.78 pmol/l, n=3). Reverse-phase high performance liquid chromatography showed that immunoreactive-AM2/IMD in human brain, kidney and plasma extracts were eluted in the position of authentic AM2/IMD. Additional peaks eluted earlier were found in the brain tissue and plasma. Immunocytochemistry showed that immunoreactive-AM2/IMD was localized in paraventricular and supraoptic nuclei of hypothalamus, anterior and posterior lobes of pituitary, cardiomyocytes, pericardial adipocytes, vascular endothelial cells of pericardial veins, and vascular smooth muscle cells of coronary arteries and renal arterioles as well as in renal tubular cells. The present study has shown expression of AM2/IMD in various types of cells in the central nervous system and the cardiovascular system, and suggested possible (patho)physiological roles of AM2/IMD in these systems.

Brain-type Natriuretic Peptide Release and Seizure Activity during Vagal Nerve Stimulation

Vagus nerve stimulation (VNS) has emerged as an effective adjunctive therapy for medically refractory epilepsy when surgery is inadvisable. N-terminal brain-type natriuretic peptide (NT-proBNP) is a potent natriuretic, diuretic, and vasodilatative compound first discovered in the human brain but mainly synthesized in the myocardium. The monitoring of VNS effectiveness in reducing seizure frequency or the detection of possible cardiac adverse effects would be helped by a reliable biochemical marker, which has not been available thus far. We report a four-year-old boy with drug-resistant idiopathic generalized epilepsy whose NT-proBNP levels increased during VNS and seizures.

Brain-type Natriuretic Peptide Secretion Following Febrile and Afebrile Seizures?A New Marker in Childhood Epilepsy?

PURPOSE

Markers for epileptic seizures are rare and their use has not been established in the evaluation of seizures and febrile convulsions (FC). Brain-type natriuretic peptide (BNP) is a natriuretic, diuretic, and vasodilator compound first discovered in the hypothalamus but mainly synthesized in the myocardium. The aim of this study was to assess whether epileptic seizures or FC are related to increased secretion of the N-terminal fragment of BNP (NT-proBNP).

METHODS

Sixty-five postictal children (43 boys, 22 girls) and 31 children with epilepsy (20 boys, 11 girls) after a seizure-free period for at least 2 months serving as controls were enrolled. Postictal NT-proBNP levels were analyzed and controlled 24-48 h thereafter.

RESULTS

Plasma concentration of NT-proBNP was significantly higher 4 h postictal compared to 24-48 h postictal (p < 0.001). Subgroup analysis revealed increased NT-proBNP levels in children with tonic-clonic seizures and FC compared to children with partial motor seizures (p < 0.001), syncope (SYN; p < 0.01), or control population (p < 0.001).

CONCLUSIONS

Our results suggest that elevated plasma NT-proBNP levels are not specific for cardiac dysfunction. Postictal measurement of plasma NT-proBNP seems to be useful in discriminating different types of epilepsy, FC, and SYN in childhood.

Diagnosis and management of cerebral salt wasting (CSW) in children: the role of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP)

OBJECTIVE

The aim of this study is to report our experience with diagnosis and management of cerebral salt wasting (CSW) in children and to evaluate the role of atrial natriuretic peptide/brain natriuretic peptide (ANP/BNP) in pediatric patients.

MATERIALS AND METHODS

We present nine children suffering from prevalent cerebral disease--seven of whom underwent anesthesia and surgical procedures--with features of CSW, seen within a 22-month period. The symptoms, patient characteristics (including hormone status), monitoring, treatment protocol, and outcome are described.

RESULTS

Natriuresis (urine Na+ concentrations 131 to >250 mmol/l) and polyuria (5.5+/-1.5 ml/kg/h) with increased Na+ turnover (maximum Na+ loss: median 1.50 mmol Na+/kg/h, range 0.47 to >3.50) vanished within 2 weeks in 6/9 patients (increase in serum Na+ from 127+/-2 mmol/l to 136+/-1). K+ excretion was also high (maximum K+ loss: median 0.18 mmol K+/kg/h, range 0.09-0.53). ANP/BNP as suspected causes of salt wasting were elevated only in 1/6 and 2/7 patients, respectively. Plasma renin activities and aldosterone levels were either suppressed or in the low normal range.

CONCLUSION

Natriuresis and polyuria are the main diagnostic criteria for CSW. The fluid balance in CSW is negative, in contrast to a positive fluid balance in SIADH. The length of the disease is self-limited and generally ceases within 2 weeks, while Na+, K+, and fluid turnover should be monitored carefully. Only a minority of our children showed elevated ANP/BNP levels. A dose/effect relationship for natriuretic peptide levels and increased Na+ turnover could not be established.

Intrathecal and Systemic Concentration of NT-proBNP in Patients with Severe Traumatic Brain Injury

Outcome of patients suffering from traumatic brain injury (TBI) depends on the development of secondary brain damage. In this context, recent studies underlined the role of the natriuretic peptides- atrial natriuretic peptide and brain natriuretic peptide (BNP)-in aneurysmatic subarachnoidal hemorrhage (SAH). Especially BNP correlates with intracranial pressure and clinical outcome after SAH. Since its role in TBI remains unclear, the intracranial and systemic concentrations of N-terminal (NT)-proBNP were analyzed in patients suffering from severe TBI. We measured NT-proBNP levels in cerebrospinal fluid (CSF) and serum of 14 patients suffering from severe TBI (GCS<or=8 points) and 10 healthy control patients, using proBNP assay (Roche Diagnostics). Samples were collected after placement of a ventricular catheter, and at 12, 24, 48, and 72 h after TBI. CSF/serum albumin ratio (Q<a) was daily calculated. At 90 days after TBI, outcome was evaluated using the Glasgow Outcome Scale (GOS). In patients exhibiting a mean ICP of >15 mm Hg (n=6), the serum (800+/-150 pg/mL) and CSF levels (55+/-9 pg/mL) of NT-proBNP were significantly increased after 24 h, as compared to patients with ICP<or=15 mm of Hg (n=8) as well as to control group. However, Qa as well as GOS did not significantly differ among both groups. For the first time, we evaluated intrathecal and systemic NT-proBNP concentrations in patients suffering from severe TBI. Interestingly, NT-proBNP in CSF and serum was significantly elevated in patients exhibiting an ICP of >15 mm Hg. Further studies are currently performed to elucidate the physiologic role of NT-proBNP in TBI.

Expression of orexin-A and orexin receptors in the kidney and the presence of orexin-A-like immunoreactivity in human urine

Orexin-A (hypocretin-1), a neuropeptide with stimulatory actions on arousal and appetite, was originally shown to be specifically expressed in the hypothalamus. We studied expression of orexin-A and orexin receptors in the kidney and the presence of orexin-A-like immunoreactivity in human urine. Immunocytochemistry showed that orexin-A-like immunoreactivity and two types of orexin receptors (types 1 and 2) were localized in the tubules of the human kidney obtained at autopsy. Orexin-A-like immunoreactivity was detected in human kidneys (21.3 +/- 6.2 fmol/g wet weight, mean +/- S.E.M., n = 4) and rat kidneys (16.2 +/- 1.6 fmol/g wet weight, n = 5) by radioimmunoassay, although the levels were much lower than the levels in the brain. Orexin-A-like immunoreactivity was present in the urine obtained from male healthy volunteers (67.8 +/- 4.5 pmol/l, n = 5). Reverse phase high-performance liquid chromatography showed that most of orexin-A-like immunoreactivity of the urine extract was eluted earlier than authentic orexin-A, suggesting that orexin-A-like immunoreactivity in urine was modified to hydrophilic forms. Reverse transcriptase polymerase chain reaction showed expression of orexin receptors 1 and 2 mRNAs in the human kidney. These findings suggest that orexin-A is produced by the renal tubular cells and secreted into urine. Orexin-A may act on the kidney in the autocrine or paracrine fashion, or via the urine (urocrine fashion).

N-terminal pro-brain natriuretic peptide levels are elevated in patients with acute ischemic stroke

Brain natriuretic peptide (BNP) is a counterregulatory hormone released by the ventricles of the heart. Its main actions are natriuresis and vasodilation. The authors studied N-terminal pro-brain natriuretic peptide (NT-proBNP) levels soon after an acute ischemic stroke. They compared plasma NT-proBNP concentrations in 30 patients with an acute ischemic stroke with those of 30 controls. The 2 groups were adjusted for age and gender, and there were no significant differences in vascular risk factors and left ventricular systolic and diastolic function. Venous samples were collected within the first 11.8 +/-1.2 hours after the onset of symptoms and again on day 6. Brain computed tomography/magnetic resonance imaging (CT/MRI) was performed on the same days (day 0 and day 6) in order to assess the site (carotid or vertebrobasilar), cause (atherothrombotic, cardioembolic, or lacunar), and size (large, medium, or small) of the brain infarct. NT-proBNP levels were elevated in patients with acute stroke (129.9 +/-9.9 fmol/mL) compared with the controls (90.8 +/-6.3 fmol/mL, p <0.05). These levels remained elevated at day 6 (113.5 +/-13.0 fmol/mL). NT-proBNP at admission was significantly higher in cardioembolic compared with atherothrombotic infarctions. There was no correlation between circulating NT-proBNP and stroke topography, infarct size, or severity as assessed by the National Institutes of Health Stroke Scale (NIHSS) at any of the 2 time points (admission and day 6). NT-proBNP levels were raised in patients with acute ischemic stroke; this effect persisted until day 6. The authors suggest that neurohumoral activation occurs in patients with acute ischemic stroke, either reflecting a counterbalancing vasodilating response to the cerebral ischemia or direct myocardial dysfunction.

Expression of urocortin 3/stresscopin in human adrenal glands and adrenal tumors

Urocortin 3 (Ucn 3)/stresscopin (SCP) is a novel peptide of the corticotropin-releasing factor (CRF) family and is a specific ligand for the CRF type 2 receptor. In the present study, we studied expression of Ucn3/SCP in the normal adrenal and adrenal tumors by radioimmunoassay and reverse transcriptase-polymerase chain reaction (RT-PCR). High concentrations of immunoreactive (IR)-Ucn3 were present in the normal portions of adrenal glands (4.2+/-0.51 pmol/g wet weight, mean+/-S.E.M., n = 14), and the levels were higher than those in the brain. IR-Ucn3 was also detected in the tumor tissues of aldosterone-secreting adenomas (6.2+/-0.6 pmol/g wet weight, n = 10), cortisol-secreting adenomas (5.0+/-1.2 pmol/g wet weight, n = 4), and pheochromocytomas (1.9+/-0.4 pmol/g wet weight, n = 7). Reverse phase high performance liquid chromatography showed that IR-Ucn3 in normal portions of adrenal glands and aldosterone-secreting adenomas was eluted mainly in the positions of Ucn3 and SCP with several minor peaks eluting earlier. The RT-PCR showed expression of Ucn3 mRNA in normal portions of adrenal gland (positive ratio; 4/4), aldosterone-secreting adenomas (3/4), cortisol-secreting adenomas (1/3) and pheochromocytomas (6/7). These findings indicate that Ucn3 is produced in normal adrenal and adrenal tumors (both adrenocortical tumors and pheochromocytomas), and suggest that Ucn3 acts as an autocrine or paracrine regulator in normal adrenal and adrenal tumors.

Pituitary cyst presenting with hyponatremia and increased secretion of brain natriuretic peptide

✓ In most cases of pituitary cyst there are no clinical symptoms and the lesions are found incidentally. The authors report the case of a 60-year-old man with a pituitary cyst causing visual disturbance and hyponatremia. The patient presented with appetite loss and general fatigue. On admission, blood workup showed severe hyponatremia (112 mEq/L), and bitemporal hemianopsia was observed on neurological examination. Magnetic resonance imaging revealed an intra- and suprasellar region cystic mass extending to the frontal base and hypothalamic area. The serum level of brain natriuretic peptide (BNP) was elevated (92 pg/ml) with polyuria and excessive Na excretion. Transsphenoidal surgery was performed to drain the cyst. The cyst wall was partially excised and the cystic fluid was aspirated. The secretion of BNP normalized postoperatively, and the hyponatremia and visual symptoms resolved. Histological examination, including an electron microscopy study, confirmed the diagnosis of a simple cyst. This appears to be the first reported case of a pituitary simple cyst associated with hyponatremia and an elevated BNP level.

Urocortin 3/stresscopin in human colon: possible modulators of gastrointestinal function during stressful conditions

Urocortin 3 (Ucn 3) or stresscopin (SCP) is a new member of the corticotropin-releasing factor (CRF) neuropeptide family and is a specific ligand for CRF type 2 receptor (CRF2). CRF receptors are known to be expressed in the gastrointestinal tract and are considered to play pathophysiological roles, for example, in gastrointestinal motility under stress. We, therefore, examined Ucn 3 expression in the normal human large intestine obtained from surgery and autopsy in order to clarify this local response to stress in human intestine. Both immunohistochemistry and mRNA in situ hybridization demonstrated Ucn 3 expression in myenteric and submucosal nervous plexus, in vascular endothelial cells (VECs) and vascular smooth muscle cells (VSMCs) of blood vessels in subserosa, in smooth muscle layers of the large intestine, and in enterochromaffin cells. In contrast to Urocortin 1 (Ucn 1), Ucn 3 was hardly detected in lamina propria (LP) inflammatory cells in colonic mucosa. In addition, immunohistochemistry demonstrated CRF2 expression in myenteric and submucosal nervous plexus, in smooth muscle layers, in VECs, in VSMCs and in lamina propria inflammatory cells. Immunoreactive Ucn 3 was also detected in the large intestine by RIA, with high concentrations detected in the rectum (15.4+/-9.5 pmol/g wet weight, mean+/-SEM, n=3) and sigmoid colon (6.5+/-3.5 pmol/g wet weight, n=5). Reverse-phase HPLC of the human large intestine disclosed peaks eluting in the position of synthetic Ucn 3 or SCP. These findings all suggest that Ucn 3 plays some physiological or pathological roles in the modulation of gastrointestinal functions during stressful conditions in different manners from Ucn 1.

Enhanced antinociception by intracerebroventricularly and intrathecally-administered orexin A and B (hypocretin-1 and -2) in mice

Orexins are neuropeptides located exclusively in neurons of the lateral hypothalamic area, which send projections to most monoaminergic nuclei, such as noradrenergic locus coeruleus, dopaminergic ventral tegmental areas, and histaminergic tuberomammillary nuclei. The present work was carried out to examine the role of orexins in nociception in mice. C57BL/6 mice were administered with orexin A and B intracerebroventricularly (i.c.v.), intrathecally (i.t.) and subcutaneously (s.c.) to reveal the sites of action of these peptides and to examine the pain thresholds using four kinds of nociceptive tasks. Orexins showed antinociceptive effects in all four types of assays for thermal (hot-plate, tail-flick, paw-withdrawal), mechanical (tail-pressure), chemical (formalin, capsaicin and abdominal stretch) nociceptions and nociceptin-induced behavioral responses, when administered i.c.v. or i.t., whereas the s.c. administration was ineffective. The antinociceptive effects of orexin A were more remarkable than those of orexin B. The i.c.v. administration of orexin A was as effective as, or more potent than the i.t. administration. The effects of orexin A were completely blocked by adenosine type 1 receptor antagonists, 1,3-dipropyl-8-cyclopentylxanthine (DPCPX) and theophylline, but not by naloxone, suggesting a possible involvement of the adenosine-containing neurons and/or the adenosine pathway in these orexin actions. The i.c.v. administration of nociceptin had no significant effects on orexin expression in the brain and spinal cord. The present findings suggest that orexins have an antinociceptive role in at least four different types of pains, probably acting on both the brain and spinal cord.