Biomarkers-Directed Strategies to Treat Autism

Autism is a neurodevelopmental disorder characterized by social, communication, and behavioral symptoms. Recent research has attempted to identify the potential mechanisms that may contribute to the pathogenesis of autism. Biomarkers as noninvasive quantitative biological measures with accurate indication of a specific mechanism can lead to a better understanding of the pathogenesis required to design the most effective treatments of autism. There is also great hope that the discovery of valid and predictive biomarkers for this disorder will help earlier and more targeted methods for diagnosis and intervention. In this chapter, we discuss some of the current theorized mechanisms contributing to autism, including inflammation, oxidative stress, impaired detoxification, glutamate excitotoxicity, gut-microbiota-brain axis, impaired fatty acid profiling, and serotonin (5-HT)/oxytocin (OT) abnormalities as target to treat autism. Moreover, based on our understanding of the role of these mechanisms, selected treatment strategies are suggested. These strategies include nutraceuticals, probiotics/prebiotics and ω-3 supplementation, targeting glutamate transporters or selective 5-HT reuptake inhibitors, and intranasal OT treatment. Of course, the joint efforts of scientists, caregivers, and other stakeholders must combine to identify valid, clinically useful autism biomarkers that may lead to efficient treatment strategy and/or combined strategies

Mechanisms that increase vascular reactivity following spinal cord injury

© 2013 Dr. Hussain Saad Al DeraPeople with spinal cord injury (SCI) can experience episodes of dangerously high blood pressure, termed autonomic dysreflexia, in response to a range of sensory stimuli. While SCI severs bulbospinal inputs to sympathetic preganglionic neurons, the spinal reflex pathways below the lesion remain intact and are unopposed by inhibitory inputs from the brainstem. As a result, somatosympathetic reflexes can produce pronounced constriction of arterial vessels. Studies in man indicate that SCI not only modifies spinal reflexes but also increases neurovascular transmission in arterial vessels. The objective of this thesis was to gain insight into the mechanisms underlying the augmentation of neurovascular transmission that occurs following SCI. In Chapter 2, I investigated the mechanisms that underlie SCI-induced enhancement of neurovascular transmission in the rat tail artery. Isometric contractions of arterial segments from T11 spinal cord-transected and sham-operated rats were compared 6 weeks postoperatively. SCI more than doubled the amplitudes of contractions evoked by nerve stimulation. In arteries from SCI rats, but not those from sham-operated rats, the L-type Ca2+ channel blocker nifedipine reduced nerve-evoked contractions. Furthermore, while the sensitivity to the agonists phenylephrine (α1-adrenoceptor selective) and clonidine (α2-adrenoceptor selective) was unaffected by SCI, nifedipine had a greater inhibitory effect on contractions to both agents in arteries from SCI rats. In arteries from unoperated rats, the L-type Ca2+ channel agonist Bay K8644 mimicked the effects of SCI. These findings demonstrate that the SCI-induced enhancement of neurovascular transmission in rat tail artery can largely be accounted for by an increased contribution of L-type Ca2+ channels to activation of the vascular muscle. In Chapter 3, the mechanisms underlying the enhancement of neurovascular transmission produced SCI and Bay K8644 were further investigated in rat tail artery. In situ electrochemical detection of noradrenaline and electrophysiological monitoring of purinergic transmission were used to assess if Bay K8644 changed neurotransmitter release. In addition, isometric contractions of arterial segments were used to assess if SCI and Bay K8644 similarly changed the contribution of α1-adrenoceptors to nerve-evoked contractions and if interfering with sarcoplamic reticulum (SR) Ca2+ uptake modified the contribution of L-type Ca2+ channels to activation of tail arteries. Bay K8644 did not change noradrenaline-induced oxidation currents or purinergic excitatory junction potentials. Both SCI and Bay K8644 reduced blockade of nerve-evoked contractions by BMY7378 (α1D-adenoceptor antagonist), but did not change that by RS100329 (α1A-adrenoceptor antagonist). Disruption of the SR Ca2+ stores with ryanodine increased both nerve-evoked contractions and blockade of these responses by nifedipine. The findings demonstrate that SCI and Bay K8644 increase the α1A-adrenoceptor-mediated component of nerve-evoked contractions. The findings also suggest that Ca2+ entering smooth muscle via L-type channels is rapidly sequestered by the SR limiting its access to the contractile mechanism. Studies in individuals with SCI suggest the vasculature is hyperreactive to angiotensin II (Ang II). In Chapter 4, the effects of SCI on the reactivity of rat tail and mesenteric arteries to Ang II were investigated. SCI increased contractions of both vessels evoked by Ang II. In tail arteries, the facilitatory effect of Ang II on neurovascular transmission was greatly increased. In contrast, SCI did not change the facilitatory action of Ang II on neurovascular transmission in mesenteric arteries. These findings provide the first direct evidence that SCI increases the reactivity of arterial vessels to Ang II. In addition, in tail artery, the findings indicate that Ang II may contribute to amplifying spinal reflex activation of this vessel

Increase of cytosolic phospholipase A2 as hydrolytic enzyme of phospholipids and autism cognitive, social and sensory dysfunction severity

Abstract Background Autism is neurodevelopmental disorder that is characterized by developmental, behavioral, social and sensory abnormalities. Researchers have focused in last years in immunological alteration and inflammation as a hot subject in autism field. This work aims to study the alteration in phospholipids (PE, PS, and PC) together with the change in cPLA2 concentration as the main phospholipid hydrolytic enzyme in autistic patients compared to control. It was also extended to find a correlation between these biomarkers and severity of autism measured as childhood autism rating scale (CARS), Social responsiveness scale (SRS), and Short sensory profile (SSP). Methods Phospholipids (PE, PS, PC) and cPLA2 as biochemical parameters were determined in the plasma of 48 Saudi autistic male patients, categorized as mild-moderate and severe as indicated by their Childhood Autism Rating Scale (CARS), social responsiveness scale (SRS) and short sensory profile (SSP) and compared to 40 age- and gender-matched control samples. Results The reported data demonstrate significantly lower levels of PE, PS, and PC together with a significant increase in cPLA2. While association between severity of autism and impaired phospholipid concentration was completely lacked, an association between cPLA2 and impaired sensory processing was observed. Conclusions The impaired phospholipid level and remarkable increased in cPLA2 concentration asserted their roles in the etiology of autism. Receiver operating characteristic analysis together with predictiveness diagrams proved that the measured parameters could be used as predictive biomarkers of clinical symptoms and provide significant guidance for future therapeutic strategy to re-establish physiological homeostasis

Calcium channel currents recorded from tail artery vascular smooth muscle cells (SMCs) are not changed by spinal cord injury (SCI).

<p>(<b>A, B</b>) Ba²⁺ currents elicited by a 250 ms depolarizing step to +10 mV from a holding potential of −80 mV in a representative SMC from a sham-operated (control) rat (<b>A</b>) and a SCI rat (<b>B</b>) before (basal) and during application of Bay K8644 (1 µM). (<b>C</b>) Leak-subtracted current-voltage relations in control and SCI SMCs under basal conditions (control: 8 cells, <i>n</i> = 5; SCI: 9 cells, <i>n</i> = 5). (<b>D</b>) Normalized conductance-voltage relations for currents from control and SCI SMCs. The activation and inactivation curves in each case are the least squares-fit to the Boltzmann equation. (<b>E</b>) Current-voltage relations in control and SCI SMCs in the presence of Bay K8644 (1 µM) (control: 8 cells, n = 5; SCI: 9 cells, n = 5). (<b>F</b>) Mean increase in current amplitude produced stepping from −80 mV to +10 mV in the absence and in the presence of Bay K8644 (control: 10 cells, <i>n</i> = 5; SCI: 9 cells, <i>n</i> = 5). The data are presented as means and SE and statistical comparisons were made with paired <i>t-</i>tests. **<i>P<</i>0.01.</p

The nifedipine-sensitive and nifedipine-resistant components of contractions evoked by 100 pulses at 1 Hz in control and SCI arteries with no pretreatment or pretreated with ryanodine (Ryan; 10 µM) or cyclopiazonic acid (CPZ; 1 µM).

<p>Data are presented as mean ± SE or median and interquartile range (in parentheses) and comparisons between control and SCI values were made with Student’s unpaired <i>t</i>-tests or Mann Whitney U-tests respectively (* indicates significant <i>P</i> values).</p><p>The nifedipine-sensitive and nifedipine-resistant components of contractions evoked by 100 pulses at 1 Hz in control and SCI arteries with no pretreatment or pretreated with ryanodine (Ryan; 10 µM) or cyclopiazonic acid (CPZ; 1 µM).</p

Schematic representations of the mechanisms regulating the contribution of Ca²⁺ influx via L-type Ca²⁺ channels to nerve-evoked contractions.

<p>(A) In control arteries, much of the Ca²⁺ entering the cell via L-type Ca²⁺ channels is rapidly sequestered into the sarcoplasmic reticulum (SR) limiting its access the contractile mechanism. (B) In SCI arteries, less of the Ca²⁺ entering through L-type Ca²⁺ channels is sequestered into the SR increasing its access to the contractile mechanism. (C) Bay K8644 increases Ca²⁺ entry via L-type Ca²⁺ channels overcoming the Ca²⁺ buffering capacity of the SR.</p

Both ryanodine (Ryan; 10 µM) and cyclopiazonic acid (CPZ; 1 µM) increased the blockade of nerve-evoked contractions produced by nifedipine (Nif; 1 µM) in arteries from sham-operated rats (control arteries).

<p>By contrast, only ryanodine increased the blockade of nerve-evoked contractions produced by nifedipine in arteries from spinal cord injured rats (SCI arteries). (<b>A–C</b>) Averaged overlaid traces showing contractions to 100 pulses at 1 Hz in control (<i>left traces</i>) and SCI arteries (<i>right traces</i>) in absence (<b>A</b>; <i>black line</i>) or in the presence of ryanodine (<b>B</b>; <i>black line</i>) or CPZ (<b>C</b>; <i>black line</i>) and following addition of nifedipine (<i>grey lines</i>). (<b>D, E</b>) The % blockade of contractions produced by nifedipine at the 10^th (<b>D</b>) and 100^th pulse (<b>E</b>) during the trains of stimuli in control (<i>n</i> = 6) and SCI (<i>n</i> = 6) arteries in the absence (<i>white bars</i>) or in the presence of ryanodine (<i>grey bars</i>) or CPZ (<i>black bars</i>). Data are presented as means and SEs and statistical comparisons were made with unpaired <i>t</i>-tests. *<i>P</i><0.05, **<i>P</i><0.01.</p

Both ryanodine (Ryan; 10 µM) and cyclopiazonic acid (CPZ; 1 µM) increased the amplitude of nerve-evoked contractions in arteries from sham-operated rats (control arteries) but not in those from spinal cord injured rats (SCI arteries).

<p>(<b>A, D</b>) Averaged traces showing contractions to 100 pulses at 1 Hz in control (<i>left traces</i>) and SCI arteries (<i>right traces</i>) before (<i>black line</i>) and during (<i>grey line</i>) application of ryanodine (<b>A</b>) or CPZ (<b>D</b>). (<b>B, C, E, F</b>) Increases in wall tension measured at the 10^th (<b>B, E</b>) and 100^th pulse (<b>C, F</b>) during the trains of stimuli in control (<i>n</i> = 6) and SCI (<i>n</i> = 6) arteries before (<i>white bars</i>) and during (<i>grey bars</i>) application of ryanodine (<b>B, C</b>) or CPZ (<b>E, F</b>). Data are presented as means and SEs and statistical comparisons were made with paired <i>t</i>-tests. **<i>P</i><0.01.</p

The facilitation of nerve-evoked contraction produced by Bay K8644 (0.1 µM) was greater in arteries from sham-operated rats (control arteries) than in arteries from spinal cord injured rats (SCI arteries).

<p>(<b>A</b>) Averaged traces showing contractions to 100 pulses at 1 Hz in control (<i>upper traces</i>) and SCI arteries (<i>lower traces</i>) before (<i>black line</i>) and during (<i>grey line</i>) application of Bay K8644 (0.1 µM). (<b>B</b>) Increases in wall tension measured at the 100^th pulse during the trains stimuli in control (<i>n</i> = 6) and SCI (<i>n</i> = 6) arteries before (<i>white bars</i>) and during (<i>grey bars</i>) application of Bay K8644. Data are presented as means and SEs and statistical comparisons were made with paired <i>t</i>-tests. *<i>P</i><0.05.</p