S100B protein, glia and Gilles de la Tourette syndrome

Dopamine, vocalization, and astrocytes

Dopamine, the main catecholamine neurotransmitter in the brain, is predominately produced in the basal ganglia and released to various brain regions including the frontal cortex, midbrain and brainstem. Dopamine's effects are widespread and include modulation of a number of voluntary and innate behaviors. Vigilant regulation and modulation of dopamine levels throughout the brain is imperative for proper execution of motor behaviors, in particular speech and other types of vocalizations. While dopamine's role in motor circuitry is widely accepted, its unique function in normal and abnormal speech production is not fully understood. In this perspective, we first review the role of dopaminergic circuits in vocal production. We then discuss and propose the conceivable involvement of astrocytes, the numerous star-shaped glia cells of the brain, in the dopaminergic network modulating normal and abnormal vocal productions.

Investigation of Risperidone Treatment Associated With Enhanced Brain Activity in Patients Who Stutter

Stuttering is a childhood onset fluency disorder that leads to impairment in speech. A randomized, double-blinded placebo-controlled study was conducted with 10 adult subjects to observe the effects of risperidone (a dopamine receptor 2/serotonin receptor 2 antagonist) on brain metabolism, using [¹⁸F] deoxyglucose as the marker. At baseline and after 6 weeks of taking risperidone (0.5–2.0 mg/day) or a placebo pill, participants were assigned to a solo reading aloud task for 30 min and subsequently underwent a 90-min positron emission tomography scan. Paired t-tests were performed to compare the pre-treatment vs. post-treatment in groups. After imaging and analysis, the blind was broken, which revealed an equal number of subjects of those on risperidone and those on placebo. There were no significant differences in the baseline scans taken before medication randomization. However, scans taken after active treatment demonstrated higher glucose uptake in the specific regions of the brain for those in the risperidone treatment group (p < 0.05). Risperidone treatment was associated with increased metabolism in the left striatum, which consists of the caudate and putamen, and the Broca’s area. The current study strengthens previous research that suggests the role of elevated dopamine activity and striatal hypometabolism in stuttering. We propose that the mechanism of risperidone’s action in stuttering, in part, involves increased metabolism of striatal astrocytes. We conclude that using neuroimaging techniques to visualize changes in the brain of those who stutter can provide valuable insights into the pathophysiology of the disorder and guide the development of future interventions.

Evaluation of dietary and lifestyle changes as modifiers of S100β levels in Alzheimer's disease

There is a significant body of research undertaken in order to elucidate the mechanisms underlying the pathology of Alzheimer's disease (AD), as well as to discover early detection biomarkers and potential therapeutic strategies. One such proposed biomarker is the calcium binding protein S100β, which, depending on its local concentration, is known to exhibit both neurotrophic and neuroinflammatory properties in the central nervous system. At present, relatively little is known regarding the effect of chronic S100β disruption in AD. Dietary intake has been identified as a modifiable risk factor for AD. Preliminary in vitro and animal studies have demonstrated an association between S100β expression and dietary intake which links to AD pathophysiology. This review describes the association of S100β to fatty acids, ketone bodies, insulin, and botanicals as well as the potential impact of physical activity as a lifestyle factor. We also discuss the prospective implications of these findings, including support of the use of a Mediterranean dietary pattern and/or the ketogenic diet as an approach to modify AD risk.

Diagnostic value of S100B and neuron-specific enolase in mild pediatric traumatic brain injury

OBJECT

During recent years, several biomarkers have been introduced for use in the diagnosis of traumatic brain injury (TBI). The primary objective of this investigation was to determine if S100B (or S100 calcium-binding protein B) and neuron-specific enolase (NSE) serum concentrations can effectively be used to discriminate between symptomatic and asymptomatic children with minor head trauma.

METHODS

The authors conducted a prospective clinical study that involved patients age 6 months to 15 years who had sustained minor head trauma. Children with concomitant extracranial injuries were excluded. Blood samples were obtained within 6 hours of injury to measure S100B and NSE levels in serum. The authors defined 2 diagnostic groups: a mild TBI group (patients with Glasgow Coma Scale [GCS] scores of 13-15) in whom there were clinical signs of concussion (short loss of consciousness, amnesia, nausea, vomiting, somnolence, headache, dizziness, or impaired vision) and a head contusion group (patients with a GCS score of 15) in whom symptoms were absent. Both S100B and NSE concentrations were compared between the 2 groups. Secondary end points were defined as follows: correlation of S100B/NSE and a) the presence of scalp lacerations, b) GCS score, c) age, and d) correlation between S100B and NSE.

RESULTS

One hundred forty-eight patients were enrolled (53 in the contusion group, 95 in the mild TBI group). After adjusting for differences in age and time of injury to blood sample withdrawal, there was no significant difference in S100B or NSE between patients in the 2 groups. Scalp lacerations and GCS score had no affect on posttraumatic S100B or NSE concentrations. The correlation between S100B and NSE was significant. Both markers showed a significant negative correlation with age.

CONCLUSIONS

The authors demonstrated that S100B and NSE do not discriminate between symptomatic and asymptomatic children with minor head injury. There seem to be limitations in marker sensitivity when investigating pediatric patients with mild TBI.

S100B in underweight and weight-recovered patients with anorexia nervosa

Anorexia nervosa (AN) commonly arises during adolescence, leading to interruptions of somatic and psychological development as well as to cortical atrophy and reductions of brain volume. While most brain changes shift towards normal with weight restoration, it is not certain whether they are related to the loss of brain cells, neuropil or merely due to fluid shifts. We measured S100B serum concentrations and psychometric characteristics in 34 patients with acute AN, 19 weight-recovered patients and 35 healthy control women (HCW). Plasma tryptophan and leptin levels were determined as markers for malnutrition and neuroendocrine adaptation to semi-starvation. Peripheral S100B concentrations of acute and former AN patients were not elevated and not statistically different from HCW. BMI, peripheral leptin levels and measures of psychopathology as well as executive cognitive functioning did not correlate with S100B. Plasma tryptophan was positively related to S100B. Our results are in line with our previous findings showing unaltered GFAP and NSE plasma levels in patients with acute AN. Together they do not support hypotheses comprising the degeneration of glial or neuronal cells to explain common signs of brain atrophy in patients with acute AN.

S100B in neuropathologic states: the CRP of the brain?

In recent years there has been a proliferation of interest in the brain-specific protein S100B, its many physiologic roles, and its behaviour in various neuropathologic conditions. Since the mid-1960s, its wide variety of intracellular and extracellular activities has been elucidated, and it has also been implicated in an increasing number of central nervous system (CNS) disorders. S100B is part of a superfamily of proteins, some of which (including S100B) have been implicated as calcium-dependent regulatory proteins that modulate the activity of effector proteins or cells. S100B is primarily an astrocytic protein. Within cells, it may have a role in signal transduction, and it is involved in calcium homeostasis. Information about the functional implication of S100B secretion by astrocytes into the extracellular space is scant but there is substantial evidence that secreted glial S100B exerts trophic or toxic effects depending on its concentration. This review summarises the historic development and current knowledge of S100B, including recent interesting findings relating S100B to a diversity of CNS pathologies such as traumatic brain injury, Alzheimer's disease, Down's syndrome, schizophrenia, and Tourette's syndrome. These broad implications have led some workers to describe S100B as 'the CRP (C-reactive protein) of the brain.' This review also examines S100B's potential role as a neurologic screening tool, or biomarker of CNS injury, analogous to the role of CRP as a marker of systemic inflammation.

Immunology of obsessive-compulsive disorder

Childhood OCD often develops into a chronic illness that lasts decades. Proof that some type of immunotherapy (such as antibiotic prophylaxis) could significantly reduce recurrence or exacerbation of symptoms of OC or tics would suggest a supportive role for immune triggers in the onset or worsening of these conditions and provide additional tools for improving outcome. The validity of PANDAS will continue to be questioned, however,because demonstrating a clear causation will be difficult on a background ofa common childhood illness. Along with the previously mentioned immuno-therapy study, validation of the PANDAS phenotype (broadly interpreted)would be advanced from new and continued research in the following areas: (1) prospective studies to identify infectious triggers in the onset and exacerbations of OCD spectrum disorders, (2) biological measures for immune and genetic susceptibility, and (3) large scale epidemiological studies demonstrating the relationship between infection and OCD spectrum disorders. The assimilation of these study results should allow for elucidation of the immune system's role in the onset and maintenance of OCD.

Redox modifications of the C-terminal cysteine residue cause structural changes in S100A1 and S100B proteins

S100 is a family of small, acidic, calcium binding proteins involved in the control of a multitude of intra- and extracellular processes, including many pathologies. The application of the analytical methodology based on the combination of RP HPLC and ESI-MS allowed for the characterization of S-nitrosylation and S-glutathionylation in two representative S100 proteins: S100A1 and S100B. The GSNO related S-nitrosylation of the conserved C-terminal cysteine is strongly activated by the binding of Ca(II) to S100A1 and of Ca(II) and Zn(II) to S100B. This modification results in a global alteration of protein structure, as demonstrated by a variety of techniques. The presented results provide a mechanistic basis for further studies of the function of S100 proteins in the control of redox-based and metal-based signal transduction.

Protein S-100B, neuron-specific enolase (NSE), myelin basic protein (MBP) and glial fibrillary acidic protein (GFAP) in cerebrospinal fluid (CSF) and blood of neurological patients

In this study, data about protein S-100B, neuron-specific enolase, myelin basic protein and glial fibrillary acidic protein in cerebrospinal fluid and blood of patients with an acute or chronic progressive neurological disorder with brain damage are reviewed. Especially in disorders with acute brain damage, determination of these proteins in CSF and blood can be helpful to establish structural and/or functional brain damage to determine severity and prognosis of the disease process and to monitor treatment effects.

S100B in brain damage and neurodegeneration

S100B is a calcium-binding peptide produced mainly by astrocytes that exert paracrine and autocrine effects on neurons and glia. Some knowledge has been acquired from in vitro and in vivo animal experiments to understand S100B's roles in cellular energy metabolism, cytoskeleton modification, cell proliferation, and differentiation. Also, insights have been gained regarding the interaction between S100B and the cerebral immune system, and the regulation of S100B activity through serotonergic transmission. Secreted glial S100B exerts trophic or toxic effects depending on its concentration. At nanomolar concentrations, S100B stimulates neurite outgrowth and enhances survival of neurons during development. In contrast, micromolar levels of extracellular S100B in vitro stimulate the expression of proinflammatory cytokines and induce apoptosis. In animal studies, changes in the cerebral concentration of S100B cause behavioral disturbances and cognitive deficits. In humans, increased S100B has been detected with various clinical conditions. Brain trauma and ischemia is associated with increased S100B concentrations, probably due to the destruction of astrocytes. In neurodegenerative, inflammatory and psychiatric diseases, increased S100B levels may be caused by secreted S100B or release from damaged astrocytes. This review summarizes published findings on S100B regarding human brain damage and neurodegeneration. Findings from in vitro and in vivo animal experiments relevant for human neurodegenerative diseases and brain damage are reviewed together with the results of studies on traumatic, ischemic, and inflammatory brain damage as well as neurodegenerative and psychiatric disorders. Methodological problems are discussed and perspectives for future research are outlined.