Intermittent Hypercapnic Hypoxia Induced Protein Changes in the Piglet Hippocampus Identified by MALDI-TOF-MS

Immunohistochemistry for acetylcholinesterase and butyrylcholinesterase in the dorsal motor nucleus of the vagus (DMNV) of formalin-fixed, paraffin-embedded tissue: comparison with reported literature

The majority of research regarding the expression of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) in the brain has been conducted using histochemistry to identify enzymatic activity in frozen fixed tissue. However, retrospective human neurochemistry studies are generally restricted to formalin-fixed, paraffin-embedded (FFPE) tissues that are not suitable for histochemical procedures. The availability of commercially available antibody formulations provides the means to study such tissues by immunohistochemistry (IHC). In this study, we optimised IHC conditions for evaluating the expression of AChE and BuChE in the brainstem, focusing on the dorsal motor nucleus of the vagus, in human and piglet FFPE tissues, using commercially available antibodies. Our results were compared to published reports of histochemically determined AChE and BuChE expression. We varied antibody concentrations and antigen retrieval methods, and evaluated different detection systems, with the overall aim to optimise immunohistochemical staining. The primary findings, consistent across both species, are: (1) AChE and BuChE expression dominated in the neuronal somata, specifically in the neuronal cytoplasm; and (2) no change in the protocol resulted in axonal/neuropil expression of AChE. These results indicate that IHC is a suitable tool to detect AChE and BuChE in FFPE tissue using commercial antibodies, albeit the staining patterns obtained differed from those using histochemistry in frozen tissue. The underlying cause(s) for these differences are discussed in detail and may be associated with the principal components of the staining method, the antibody protein target and/or limitations to the detection of epitopes by tissue fixation.

GLAST (GLutamate and ASpartate Transporter) in human prefrontal cortex; interactome in healthy brains and the expression of GLAST in brains of chronic alcoholics

We have analysed post-mortem samples of prefrontal cortex from control and alcoholic human brains by the technique of Western blotting to estimate and compare the expressions of glutamate transporter GLAST (Excitatory Amino Acid Transporter One; EAAT1). Furthermore, using the non-alcoholic prefrontal cortex and custom-made GLAST (EAAT1) antibody we determined GLAST (EAAT1) "interactome" i.e. the set of proteins selectively bound by GLAST (EAAT1). We found that GLAST (EAAT1) was significantly more abundant (about 1.6-fold) in the cortical tissue from alcoholic brains compared to that from non-alcoholic controls. The greatest increase in the level of GLAST (EAAT1) was found in plasma membrane fraction (2.2-fold). Additionally, using the prefrontal cortical tissue from control brains, we identified 38 proteins specifically interacting with GLAST (EAAT1). These can be classified as contributing to the cell structure (6 proteins; 16%), energy and general metabolism (18 proteins; 47%), neurotransmitter metabolism (three proteins; 8%), signalling (6 proteins: 16%), neurotransmitter storage/release at synapses (three proteins; 8%) and calcium buffering (two proteins; 5%). We discuss possible consequences of the increased expression of GLAST (EAAT1) in alcoholic brain tissue and whether or how this could disturb the function of the proteins potentially interacting with GLAST (EAAT1) in vivo. The data represent an extension of our previous proteomic and metabolomic studies of human alcoholism revealing another aspect of the complexity of changes imposed on brain by chronic long-term consumption of ethanol.

Exposure of Rat Neural Stem Cells to Ethanol Affects Cell Numbers and Alters Expression of 28 Proteins

Developing brain cells express many proteins but little is known of how their protein composition responds to chronic exposure to alcohol and/or how such changes might relate to alcohol toxicity. We used cultures derived from embryonic rat brain (previously shown to contain mostly neural stem cells; rat NSC, rNSC), exposed them to ethanol (25-100 mM) for up to 96 h and studied how they reacted. Ethanol (50 and 100 mM) reduced cell numbers indicating either compromised cell proliferation, cytotoxicity or both. Increased lipid peroxidation was consistent with the presence of oxidative stress accompanying alcohol-induced cytotoxicity. Proteomics revealed 28 proteins as altered by ethanol (50 mM for 96 h). Some were constituents of cytoskeleton, others were involved in transcription/translation, signal transduction and oxidative stress. Nucleophosmin (NPM1) and dead-end protein homolog 1 (DND1) were further studied by immunological techniques in cultured neurons and astrocytes (derived from brain tissue at embryonic ages E15 and E20, respectively). In the case of DND1 (but not NPM1) ethanol induced similar pattern of changes in both types of cells. Given the critical role of the protein NPM1 in cell proliferation and differentiation, its reduced expression in the ethanol-exposed rNSC could, in part, explain the lower cells numbers. We conclude that chronic ethanol profoundly alters protein composition of rNSC to the extent that their functioning-including proliferation and survival-would be seriously compromised. Translated to humans, such changes could point the way towards mechanisms underlying the fetal alcohol spectrum disorder and/or alcoholism later in life.

Chromatography/Mass Spectrometry-Based Biomarkers in the Field of Obstructive Sleep Apnea

Biomarker assessment is based on quantifying several proteins and metabolites. Recent developments in proteomics and metabolomics have enabled detection of these small molecules in biological samples and exploration of the underlying disease mechanisms in obstructive sleep apnea (OSA). This systemic review was performed to identify biomarkers, which were only detected by chromatography and/or mass spectrometry (MS) and to discuss the role of these biomarkers in the field of OSA. We systemically reviewed relevant articles from PubMed and EMBASE referring to proteins and metabolite profiles of biological samples in patients with OSA. The analytical platforms in this review were focused on chromatography and/or MS. In total, 30 studies evaluating biomarkers in patients with OSA using chromatography and/or MS methods were included. Numerous proteins and metabolites, including lipid profiles, adrenergic/dopaminergic biomarkers and derivatives, amino acids, oxidative stress biomarkers, and other micromolecules were identified in patients with OSA. Applying chromatography and/or MS methods to detect biomarkers helps develop an understanding of OSA mechanisms. More proteomic and metabolomic studies are warranted to develop potential diagnostic and clinical monitoring methods for OSA.

Cigarette smoking during pregnancy regulates the expression of specific nicotinic acetylcholine receptor (nAChR) subunits in the human placenta

Smoking during pregnancy is associated with low birth weight, premature delivery, and neonatal morbidity and mortality. Nicotine, a major pathogenic compound of cigarette smoke, binds to the nicotinic acetylcholine receptors (nAChRs). A total of 16 nAChR subunits have been identified in mammals (9 α, 4 β, and 1 δ, γ and ε subunits). The effect of cigarette smoking on the expression of these subunits in the placenta has not yet been determined, thus constituting the aim of this study. Using RT-qPCR and western blotting, this study investigated all 16 mammalian nAChR subunits in the normal healthy human placenta, and compared mRNA and protein expressions in the placentas from smokers (n = 8) to controls (n = 8). Our data show that all 16 subunit mRNAs are expressed in the normal, non-diseased human placenta and that the expression of α2, α3, α4, α9, β2 and β4 subunits is greater than the other subunits. For mRNA, cigarette smoke exposure was associated with increased expression of the α9 subunit, and decreased expression of the δ subunit. At the protein level, expression of both α9 and δ was increased. Thus, cigarette smoking in pregnancy is sufficient to regulate nAChR subunits in the placenta, specifically α9 and δ subunits, and could contribute to the adverse effects of vasoconstriction and decreased re-epithelialisation (α9), and increased calcification and apoptosis (δ), seen in the placentas of smoking women.

Relationship between brain-derived neurotrophic factor and cognitive function of obstructive sleep apnea/hypopnea syndrome patients

OBJECTIVE

To determine the relationship between the blood serum brain-derived neurotrophic factor (BDNF) level and cognitive function deterioration in patients with obstructive sleep apnea/hypopnea syndrome (OSAHS), and to explore the possible mechanism of cognitive impairment.

METHODS

Twenty-eight male OSAHS patients and 14 normal males (as controls) were enrolled in the study. Polysomnography and the Montreal cognitive assessment (MoCA) were conducted. The blood serum BDNF levels were measured using ELISA.

RESULTS

The OSAHS group had significantly decreased blood serum BDNF levels compared with the control group (t = -10.912, P = 0.000). The blood serum BDNF level of the subjects was significantly positively associated with the MoCA score (r = 0.544, P = 0.000), significantly negatively associated with the apnea-hypopnea index (AHI) and shallow sleep (S1+S2) (AHI: r = -0.607, P = 0.000; S1+S2: r = -0.768, P = 0.000), and significantly positively associated with the lowest SaO(2) (LSO), slow wave sleep (S3+S4), and rapid eye movement sleep (REM) (LSO: r = 0.566, P = 0.000; S3+S4: r = 0.778, P = 0.000; REM: r = 0.575, P = 0.000).

CONCLUSIONS

OSAHS patients have significantly decreased blood serum BDNF levels compared with the control. Nocturnal hypoxia as well as the deprivation of slow wave sleep and REM may lead to the decreased serum BDNF level of OSAHS patients. This decreased blood serum BDNF level may contribute to the cognitive impairment in OSAHS.