Reactive oxygen species, cellular redox systems and apoptosis

We review research evidence on the emergence and development of active "self-and-other" awareness in infancy, and examine the importance of its motives and emotions to mental health practice with children. This relates to how communication begins and develops in infancy, how it influences the individual subject's movement, perception, and learning, and how the infant's biologically grounded self-regulation of internal state and self-conscious purposefulness is sustained through active engagement with sympathetic others. Mutual self-other-consciousness is found to play the lead role in developing a child's cooperative intelligence for cultural learning and language. A variety of preconceptions have animated rival research traditions investigating infant communication and cognition. We distinguish the concept of "intersubjectivity", and outline the history of its use in developmental research. The transforming body and brain of a human individual grows in active engagement with an environment of human factors--organic at first, then psychological or inter-mental. Adaptive, human-responsive processes are generated first by interneuronal activity within the developing brain as formation of the human embryo is regulated in a support-system of maternal tissues. Neural structures are further elaborated with the benefit of intra-uterine stimuli in the foetus, then supported in the rapidly growing forebrain and cerebellum of the young child by experience of the intuitive responses of parents and other human companions. We focus particularly on intrinsic patterns and processes in pre-natal and post-natal brain maturation that anticipate psychosocial support in infancy. The operation of an intrinsic motive formation (IMF) that developed in the core of the brain before birth is evident in the tightly integrated intermodal sensory-motor coordination of a newborn infant's orienting to stimuli and preferential learning of human signals, by the temporal coherence and intrinsic rhythms of infant behaviour, especially in communication, and neonates' extraordinary capacities for reactive and evocative imitation. The correct functioning of this integrated neural motivating system is found to be essential to the development of both the infant's purposeful consciousness and his or her ability to cooperate with other persons' actions and interests, and to learn from them. The relevance of infants' inherent intersubjectivity to major child mental health issues is highlighted by examining selected areas of clinical concern. We review recent findings on postnatal depression, prematurity, autism, ADHD, specific language impairments, and central auditory processing deficits, and comment on the efficacy of interventions that aim to support intrinsic motives for intersubjective communication when these are not developing normally.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/3DC59499840534E5455EEDB895666BF6/S0021963001006552a.pdf/div-class-title-infant-intersubjectivity-research-theory-and-clinical-applications-div.pdf

Infant intersubjectivity: research, theory, and clinical applications.

Pediatricians have an important role not only in early recognition and evaluation of autism spectrum disorders but also in chronic management of these disorders. The primary goals of treatment are to maximize the child's ultimate functional independence and quality of life by minimizing the core autism spectrum disorder features, facilitating development and learning, promoting socialization, reducing maladaptive behaviors, and educating and supporting families. To assist pediatricians in educating families and guiding them toward empirically supported interventions for their children, this report reviews the educational strategies and associated therapies that are the primary treatments for children with autism spectrum disorders. Optimization of health care is likely to have a positive effect on habilitative progress, functional outcome, and quality of life; therefore, important issues, such as management of associated medical problems, pharmacologic and nonpharmacologic intervention for challenging behaviors or coexisting mental health conditions, and use of complementary and alternative medical treatments, are also addressed.

/pdf/management-of-children-with-autism-spectrum-disorders-13gotb2ppb.pdf

Management of Children With Autism Spectrum Disorders

High proportions of autistic children suffer from gastrointestinal (GI) disorders, implying a link between autism and abnormalities in gut microbial functions. Increasing evidence from recent high-throughput sequencing analyses indicates that disturbances in composition and diversity of gut microbiome are associated with various disease conditions. However, microbiome-level studies on autism are limited and mostly focused on pathogenic bacteria. Therefore, here we aimed to define systemic changes in gut microbiome associated with autism and autism-related GI problems. We recruited 20 neurotypical and 20 autistic children accompanied by a survey of both autistic severity and GI symptoms. By pyrosequencing the V2/V3 regions in bacterial 16S rDNA from fecal DNA samples, we compared gut microbiomes of GI symptom-free neurotypical children with those of autistic children mostly presenting GI symptoms. Unexpectedly, the presence of autistic symptoms, rather than the severity of GI symptoms, was associated with less diverse gut microbiomes. Further, rigorous statistical tests with multiple testing corrections showed significantly lower abundances of the genera Prevotella, Coprococcus, and unclassified Veillonellaceae in autistic samples. These are intriguingly versatile carbohydrate-degrading and/or fermenting bacteria, suggesting a potential influence of unusual diet patterns observed in autistic children. However, multivariate analyses showed that autism-related changes in both overall diversity and individual genus abundances were correlated with the presence of autistic symptoms but not with their diet patterns. Taken together, autism and accompanying GI symptoms were characterized by distinct and less diverse gut microbial compositions with lower levels of Prevotella, Coprococcus, and unclassified Veillonellaceae.

/pdf/reduced-incidence-of-prevotella-and-other-fermenters-in-38pxuvgdpx.pdf

Reduced Incidence of Prevotella and Other Fermenters in Intestinal Microflora of Autistic Children

Glucose is the obligate energetic fuel for the mammalian brain, and most studies of cerebral energy metabolism assume that the majority of cerebral glucose utilization fuels neuronal activity via oxidative metabolism, both in the basal and activated state. Glucose transporter (GLUT) proteins deliver glucose from the circulation to the brain: GLUT1 in the microvascular endothelial cells of the blood-brain barrier (BBB) and glia; GLUT3 in neurons. Lactate, the glycolytic product of glucose metabolism, is transported into and out of neural cells by the monocarboxylate transporters (MCT): MCT1 in the BBB and astrocytes and MCT2 in neurons. The proposal of the astrocyte-neuron lactate shuttle hypothesis suggested that astrocytes play the primary role in cerebral glucose utilization and generate lactate for neuronal energetics, especially during activation. Since the identification of the GLUTs and MCTs in brain, much has been learned about their transport properties, that is capacity and affinity for substrate, which must be considered in any model of cerebral glucose uptake and utilization. Using concentrations and kinetic parameters of GLUT1 and -3 in BBB endothelial cells, astrocytes, and neurons, along with the corresponding kinetic properties of the MCTs, we have successfully modeled brain glucose and lactate levels as well as lactate transients in response to neuronal stimulation. Simulations based on these parameters suggest that glucose readily diffuses through the basal lamina and interstitium to neurons, which are primarily responsible for glucose uptake, metabolism, and the generation of the lactate transients observed on neuronal activation.

https://journals.sagepub.com/doi/pdf/10.1038/sj.jcbfm.9600521

Supply and demand in cerebral energy metabolism: the role of nutrient transporters

Gastrointestinal abnormalities in children with autistic disorder.

Several reports indicate that lactate can serve as an energy substrate for the brain. The rate of oxidation of this substrate by cultured rat brain astrocytes was 3-fold higher than the rate with glucose, suggesting that lactate can serve as an energy source for these cells. Since transport into the astrocytes may play an important role in regulating nutrient use by individuals types of brain cells, we investigated the uptake ofl-[U-14C]lactate by primary cultures of rat brain astrocytes. Measurement of the net uptake suggested two carrier-mediated mechanisms and an Eadie-Hofstee type plot of the data supported this conclusion revealing 2 Km values of 0.49 and 11.38 mM and Vmax values of 16.55 and 173.84 nmol/min/mg protein, respectively. The rate of uptake was temperature dependent and was 3-fold higher at pH 6.2 than at 7.4, but was 50% less at pH 8.2. Although the lactate uptake carrier systems in astrocytes appeared to be labile when incubated in phosphate buffered saline for 20 minutes, the uptake process exhibited an accelerative exchange mechanism. In addition, lactate uptake was altered by several metabolic inhibitors and effectors. Potassium cyanide and α-cyano-4-hydroxycinnamate inhibited lactate uptake, but mersalyl had little or no effect. Phenylpyruvate, α-ketoisocaproate, and 3-hydroxybutyrate at 5 and 10 mM greatly attenuated the rate of lactate uptake. These results suggest that the availability of lactate as an energy source is regulated in part by a biphasic transport system in primary astrocytes.

Transport ofl-lactate by cultured rat brain astrocytes

It is well documented that the brain preferentially utilizes alternative substrates for energy during brain development; however, less is known about the use of these substrates by synaptic terminals.

Energy Metabolism in Cortical Synaptic Terminals from Weanling and Mature Rat Brain: Evidence for Multiple Compartments of Tricarboxylic Acid Cycle Activity

Mitochondrial malic enzyme activity is much higher in mitochondria from cortical synaptic terminals compared with mitochondria from primary cultures of cortical neurons or cerebellar granule cells.

Glucose is the primary carbon source to enter the adult brain for catabolic and anabolic reactions. Some studies suggest that astrocytes may metabolize glucose to lactate; the latter serving as a preferential substrate for neurons, especially during neuronal activation. The current study utilizes the aconitase inhibitor fluorocitrate to differentially inhibit oxidative metabolism in glial cells in vivo. Oxidative metabolism of 14C-lactate and14C-glucose was monitored in vivo using microdialysis and quantitating 14CO2 in the microdialysis eluate following pulse labeling of the interstitial glucose or lactate pool. After establishing a baseline oxidation rate, fluorocitrate was added to the perfusate. Neither lactate nor glucose oxidation was affected by 5 μmol/L fluorocitrate. However, 20 and 100 μmol/L fluorocitrate reduced lactate oxidation by 55 ± 20% and 68 ± 12%, respectively (p < 0.05 for both). Twenty and 100 μmol/L fluorocitrate reduced 14C-glucose oxidation by 50 ± 14% (p < 0.05) and 24 ± 19% (ns), respectively. Addition of non-radioactive lactate to 14C-glucose plus fluorocitrate decreased 14C-glucose oxidation by an additional 29% and 38%, respectively. These results indicate that astrocytes oxidize about 50% of the interstitial lactate and about 35% of the glucose. By subtraction, neurons metabolize a maximum of 50% of the interstitial lactate and 65% of the interstitial glucose.

J. Tyson Tildon

Papers

Gastrointestinal abnormalities in children with autistic disorder.

Transport ofl-lactate by cultured rat brain astrocytes

Energy Metabolism in Cortical Synaptic Terminals from Weanling and Mature Rat Brain: Evidence for Multiple Compartments of Tricarboxylic Acid Cycle Activity

Mitochondrial malic enzyme activity is much higher in mitochondria from cortical synaptic terminals compared with mitochondria from primary cultures of cortical neurons or cerebellar granule cells.

Effect of fluorocitrate on cerebral oxidation of lactate and glucose in freely moving rats.