Mercury as a hapten: A review of the role of toxicant-induced brain autoantibodies in autism and possible treatment considerations

BACKGROUND

Mercury has many direct and well-recognized neurotoxic effects. However, its immune effects causing secondary neurotoxicity are less well-recognized. Mercury exposure can induce immunologic changes in the brain indicative of autoimmune dysfunction, including the production of highly specific brain autoantibodies. Mercury, and in particular, Thimerosal, can combine with a larger carrier, such as an endogenous protein, thereby acting as a hapten, and this new molecule can then elicit the production of antibodies.

METHODS

A comprehensive search using PubMed and Google Scholar for original studies and reviews related to autism, mercury, autoantibodies, autoimmune dysfunction, and haptens was undertaken. All articles providing relevant information from 1985 to date were examined. Twenty-three studies were identified showing autoantibodies in the brains of individuals diagnosed with autism and all were included and discussed in this review.

RESULTS

Research shows mercury exposure can result in an autoimmune reaction that may be causal or contributory to autism, especially in children with a family history of autoimmunity. The autoimmune pathogenesis in autism is demonstrated by the presence of brain autoantibodies (neuroantibodies), which include autoantibodies to: (1) human neuronal progenitor cells; (2) myelin basic protein (MBP); (3) neuron-axon filament protein (NAFP); (4) brain endothelial cells; (5) serotonin receptors; (6) glial fibrillary acidic protein (GFAP); (7) brain derived neurotrophic factor (BDNF); (8) myelin associated glycoprotein (MAG); and (9) various brain proteins in the cerebellum, hypothalamus, prefrontal cortex, cingulate gyrus, caudate putamen, cerebral cortex and caudate nucleus.

CONCLUSION

Recent evidence suggests a relationship between mercury exposure and brain autoantibodies in individuals diagnosed with autism. Moreover, brain autoantibody levels in autism are found to correlate with both autism severity and blood mercury levels. Treatments to reduce mercury levels and/or brain autoantibody formation should be considered in autism.

Cerebral hypoperfusion in autism spectrum disorder

Cerebral hypoperfusion, or insufficient blood flow in the brain, occurs in many areas of the brain in patients diagnosed with autism spectrum disorder (ASD). Hypoperfusion was demonstrated in the brains of individuals with ASD when compared to normal healthy control brains either using positron emission tomography (PET) or single‑photon emission computed tomography (SPECT). The affected areas include, but are not limited to the: prefrontal, frontal, temporal, occipital, and parietal cortices; thalami; basal ganglia; cingulate cortex; caudate nucleus; the limbic system including the hippocampal area; putamen; substantia nigra; cerebellum; and associative cortices. Moreover, correlations between symptom scores and hypoperfusion in the brains of individuals diagnosed with an ASD were found indicating that the greater the autism symptom pathology, the more significant the cerebral hypoperfusion or vascular pathology in the brain. Evidence suggests that brain inflammation and vascular inflammation may explain a part of the hypoperfusion. There is also evidence of a lack of normal compensatory increase in blood flow when the subjects are challenged with a task. Some studies propose treatments that can address the hypoperfusion found among individuals diagnosed with an ASD, bringing symptom relief to some extent. This review will explore the evidence that indicates cerebral hypoperfusion in ASD, as well as the possible etiological aspects, complications, and treatments.

An exploratory study of visual sequential processing in children with cochlear implants

OBJECTIVE

The objective of the study was to compare visual sequential processing in school-age children with cochlear implants (CIs) and their normal-hearing (NH) peers. Visual sequential processing was examined using both behavioral and an event-related potential (ERP) measures.

METHODS

Eighteen children with CIs and nineteen children who had hearing within normal limits (NH) participated in the behavioral study. Subtests from the Test of Visual Perceptual Skills and the Sensory Integration and Praxis Test were administered to all children. ERP measures were collected from five children with CI and five age-matched peers. Peak latencies (N200 and P300) and reaction times for visual sequential processing were compared in these two groups.

RESULTS

The findings of the study revealed significant group differences in visual sequential memory and visuo-motor sequencing tasks suggesting that children with severe-profound hearing loss may have difficulties in visual sequential tasks. The study also revealed longer P300 latencies and longer reaction times for a visual sequential matching task in children with CI when compared to their NH peers suggesting slower or delayed processing of visual sequential stimuli.

CONCLUSIONS

This exploratory study involving behavioral and ERP measures showed that as a group, children with prelingual, severe-profound hearing loss who use CIs have difficulties with visual sequential processing. These findings may have implications for rehabilitation for children with hearing loss in the light of recent evidence that accurate and efficient processing of sequentially presented visual stimuli is important for language and reading outcomes.

Shared Brain Connectivity Issues, Symptoms, and Comorbidities in Autism Spectrum Disorder, Attention Deficit/Hyperactivity Disorder, and Tourette Syndrome

The prevalence of neurodevelopmental disorders, including autism spectrum disorder (ASD), attention deficit/hyperactivity disorder (ADHD), and Tourette syndrome (TS), has increased over the past two decades. Currently, about one in six children in the United States is diagnosed as having a neurodevelopmental disorder. Evidence suggests that ASD, ADHD, and TS have similar neuropathology, which includes long-range underconnectivity and short-range overconnectivity. They also share similar symptomatology with considerable overlap in their core and associated symptoms and a frequent overlap in their comorbid conditions. Consequently, it is apparent that ASD, ADHD, and TS diagnoses belong to a broader spectrum of neurodevelopmental illness. Biologically, long-range underconnectivity and short-range overconnectivity are plausibly related to neuronal insult (e.g., neurotoxicity, neuroinflammation, excitotoxicity, sustained microglial activation, proinflammatory cytokines, toxic exposure, and oxidative stress). Therefore, these disorders may a share a similar etiology. The main purpose of this review is to critically examine the evidence that ASD, ADHD, and TS belong to a broader spectrum of neurodevelopmental illness, an abnormal connectivity spectrum disorder, which results from neural long-range underconnectivity and short-range overconnectivity. The review also discusses the possible reasons for these neuropathological connectivity findings. In addition, this review examines the role and issue of axonal injury and regeneration in order to better understand the neuropathophysiological interplay between short- and long-range axons in connectivity issues.

Prospective, blinded exploratory evaluation of the PlayWisely program in children with autism spectrum disorder

The purpose of the study was to explore a low-cost intervention that targets an increasingly common developmental disorder. The study was a blinded, exploratory evaluation of the PlayWisely program on autism symptoms and essential learning foundation skills (attention, recognition, and memory skills) in children with a diagnosis of autism, autism spectrum disorder (ASD), pervasive developmental disorder - not otherwise specified (PDD-NOS), and Asperger syndrome (AS). Eighteen children, 1 to 10 years of age, were evaluated using the Childhood Autism Rating Scale, Second Edition (CARS2); the PlayWisely Interactive Test of Attention, Recognition, and Memory Skills; Autism Treatment Evaluation Checklist (ATEC), and the Modified Checklist for Autism in Toddlers (M-CHAT). There were significant treatment effects for the PlayWisely measure on the Yellow Sets that examine recognition; Purple Sets that examine brain region agility and early memory skills; Blue Sets that examine phonemic awareness and recognition; and for the Total Sets, with a similar trend toward improvement in the Green Sets that examine perception and Red Sets that examine attention. No other measures reached statistical significance. The results suggest that PlayWisely can improve recognition, brain region agility, phonemic awareness, letter recognition, and early memory skills in ASD. It was observed by the parents, coaches, and study investigators that the children who were less than 3 years of age showed improvements in autism symptoms; however, the group was too small to reach statistical significance. Future studies are needed to see if this intervention can mitigate autism symptoms in very young children with ASD.

Prospective trial of equine-assisted activities in autism spectrum disorder

BACKGROUND

Anecdotal reports and some studies suggest that equine-assisted activities may be beneficial in autism spectrum disorders (ASD).

OBJECTIVE

To examine the effects ofequine-assisted activities on overall severity of autism symptoms using the Childhood Autism Rating Scale (CARS) and the quality ofparent-child interactions using the Timberlawn Parent-Child Interaction Scale. In addition, this study examined changes in sensory processing, quality of life, and parental treatment satisfaction.

DESIGN AND PARTICIPANTS

Children with ASD were evaluated at four time points: (1) before beginning a 3-to-6 month waiting period, (2) before starting the riding treatment, and (3) after 3 months and (4) 6 months of riding. Twenty-four participants completed the waiting list period and began the riding program, and 20 participants completed the entire 6 months of riding. Pretreatment was compared to posttreatment with each child acting as his or her own control.

RESULTS

A reduction in the severity of autism symptoms occurred with the therapeutic riding treatment. There was no change in CARS scores during the pretreatment baseline period; however, there was a significant decrease after treatment at 3 months and 6 months of riding. The Timberlawn Parent-Child Interaction Scale showed a significant improvement in Mood and Tone at 3 months and 6 months of riding and a marginal improvement in the reduction of Negative Regard at 6 months of riding. The parent-rated quality of life measure showed improvement, including the pretreatment waiting period. All of the ratings in the Treatment Satisfaction Survey were between good and very good.

CONCLUSION

These results suggest that children with ASD benefit from equine-assisted activities.

Toxicity biomarkers in autism spectrum disorder: a blinded study of urinary porphyrins

BACKGROUND

  Recent studies suggest that children diagnosed with an autism spectrum disorder (ASD) have significantly increased levels of urinary porphyrins associated with mercury (Hg) toxicity, including pentacarboxyporphyrin (5cxP), precoproporphyrin (prcP), and coproporphyrin (cP), compared to typically developing controls. However, these initial studies were criticized because the controls were not age- and gender-matched to the children diagnosed with an ASD.

METHODS

  Urinary porphyrin biomarkers in a group of children (2-13 years of age) diagnosed with an ASD (n= 20) were compared to matched (age, gender, race, location, and year tested) group of typically developing controls (n= 20).

RESULTS

  Participants diagnosed with an ASD had significantly increased levels of 5cxP, prcP, and cP in comparison to controls. No significant differences were found in non-Hg associated urinary porphyrins (uroporphyrins, hexacarboxyporphyrin, and heptacarboxyporphyrin). There was a significantly increased odds ratio for an ASD diagnosis relative to controls among study participants with precoproporphyrin (odds ratio = 15.5, P < 0.01) and coproporphyrin (odds ratio = 15.5, P < 0.01) levels in the second through fourth quartiles in comparison to the first quartile.

CONCLUSION

  These results suggest that the levels of Hg-toxicity-associated porphyrins are higher in children with an ASD diagnosis than controls. Although the pattern seen (increased 5cxP, prcP, and cP) is characteristic of Hg toxicity, the influence of other factors, such as genetics and other metals cannot be completely ruled out.

Toxicity biomarkers among US children compared to a similar cohort in France: a blinded study measuring urinary porphyrins

The purpose of this blinded study was to evaluate potential environmental toxicity in a cohort of neurotypical children (n = 28) living in a suburban area of north-central Texas in the United States (US) with a comparable age- and gender-matched cohort of neurotypical children (n = 28) living in a suburban area of southeastern France using urinary porphyrin testing: uroporphyrin (uP), heptacarboxyporphyrin (7cxP), hexacarboxyporphyrin (6cxP), pentacarboxyporphyrin (5cxP), precoproporphyrin (prcP), and coproporphyrin (cP). Results showed significantly elevated 6cxP, prcP (an atypical, mercury-specific porphyrin), and cP levels, and increasing trends in 5cxP levels, among neurotypical children in the USA compared to children in France. Data suggest that in US neurotypical children, there is a significantly increased body-burden of mercury (Hg) compared to the body-burden of Hg in the matched neurotypical children in France. The presence of lead contributing to the higher levels of cP also needs to be considered. Further, other factors including genetics can not be completely ruled out.

Sensory correlations in autism

This study examined the relationship between auditory, visual, touch, and oral sensory dysfunction in autism and their relationship to multisensory dysfunction and severity of autism. The Sensory Profile was completed on 104 persons with a diagnosis of autism, 3 to 56 years of age. Analysis showed a significant correlation between the different processing modalities using total scores. Analysis also showed a significant correlation between processing modalities for both high and low thresholds, with the exception that auditory high threshold processing did not correlate with oral low threshold or touch low threshold processing. Examination of the different age groups suggests that sensory disturbance correlates with severity of autism in children, but not in adolescents and adults. Evidence from this study suggests that: all the main modalities and multisensory processing appear to be affected; sensory processing dysfunction in autism is global in nature; and sensory processing problems need to be considered part of the disorder.

The pattern of sensory processing abnormalities in autism

The study was undertaken to evaluate the nature of sensory dysfunction in persons with autism. The cross-sectional study examined auditory, visual, oral, and touch sensory processing, as measured by the Sensory Profile, in 104 persons with a diagnosis of autism, 3-56 years of age, gender-and age-matched to community controls. Persons with autism had abnormal auditory, visual, touch, and oral sensory processing that was significantly different from controls. This finding was also apparent when the high and low thresholds of these modalities were examined separately. At later ages for the group with autism, lower levels of abnormal sensory processing were found, except for low threshold touch, which did not improve significantly. There was a significant interaction in low threshold auditory and low threshold visual, suggesting that the two groups change differently over time on these variables. These results suggest that sensory abnormalities in autism are global in nature (involving several modalities) but have the potential to improve with age.

Complementing behavioral measures with electrophysiological measures in diagnostic evaluation: a case study in two languages

This case study focuses on a bilingual, older man who spoke Polish and English and showed weaknesses on clinical measures of dichotic listening in English. It was unclear whether these test results were influenced by the participant's facility with his second language or by other nonauditory factors. To elucidate the nature of this deficit, the authors examined behavioral and electrophysiological responses during dichotic-listening tasks involving linguistic processing in both languages. A diotic (control) condition was included to examine whether nonauditory factors, such as language familiarity, memory, or decline in speed of mental processing, might explain the dichotic results. The results from this participant were compared with those obtained from a bilingual young adult who also spoke both Polish and English. Results showed a substantial left-ear deficit for the older individual on both behavioral and electrophysiological measures of dichotic listening. The pattern of results is consistent with previous findings in demonstrating that the left-ear deficit in this patient derived from an auditory-specific defect rather than from any of the extra-auditory factors associated with language facility or cognitive decline.

Local osteopenia associated with management of intra-articular distal radial fractures by insertion of external fixation pins in the distal fragment: prospective study

PURPOSE

To assess the restoration of the bone mass of the distal radius following the use of implants in the distal radial fragment. Highly comminuted Frykman type 7 and 8 fractures were studied to determine whether the use of fixation pins in the comminuted distal radial fragment leads to osteopenia in the distal radial fragment after healing of the fracture.

METHODS

As part of a clinical trial, 30 patients with comminuted intra-articular fractures of the distal radius were treated with closed reduction, external non-bridging fixation, and early postoperative mobilisation. To detect local osteopenia, bone density measurements were taken at the distal metaphysis and mid-diaphysis following healing of the fractured radius and the contralateral unaffected radius in 12 patients.

RESULT

The mean age of the 12 patients for whom bone density measurements were recorded was 52.5 years (range, 39-87 years). There were 9 females and 3 males included in the study. Seven patients had a Frykman type 8 fracture and 5 patients had a Frykman type 7 fracture. Significant osteopenia was absent despite the use of four 2.5-mm fixation pins in the distal fragments of the healed distal radial fracture. The median value of the maximal step was 2.8 mm (range, 0-9.1 mm). The median value of the intra-articular interfragmentary gap was 1.8 mm (range, 0-13.4mm).

CONCLUSION

The findings of this study do not suggest long-term osteopenia following the use of four 2.5-mm pins in the distal fragments. The non-bridging fixator, by allowing early physical activity, possibly led to satisfactory functional and structural results.

Anatomical reduction of intra-articular fractures of the distal radius. An arthroscopically-assisted approach

We treated 31 intra-articular fractures of the distal radius by arthroscopically-assisted reduction and percutaneous fixation with Kirschner (K-) wires. Tears of the triangular fibrocartilage (58 %), scapholunate (85 %) and lunotriquetral (61%) instability and osteochondral lesions (19%) were also treated. A total of 26 patients was independently reviewed at an average of 19 months. The mean pain score was 1.3/10, the range of movement 79% and the grip strength 90% of the contralateral wrist. Using the New York Orthopaedic Hospital score, 88% were graded excellent to good. On follow-up radiographs, 65% had no step and 31% had a step of < or =1 mm. Pain was significantly related to the size of the step. There was a significant difference in the incidence of persistent scapholunate diastasis and the Leibovic and Geissler grade (p < 0.01): I (0%), II (0%), III (42%) and IV (100%). We recommend anatomical reduction and acceptance of a step of <1 mm since the size of the step is related to the incidence of pain.

Surgical approaches to the elbow

The recent explosion of interest in the elbow and the need for better surgical approaches, has produced numerous new approaches and the modification of other approaches, the result of which is a much shorter but more useful list of surgical approaches. Surgeons who perform a large number of elbow procedures have found that these approaches permit them to perform the majority of elbow procedures with only one skin incision, usually a straight posterior midline incision. Knowledge of the deep intermuscular and internervous intervals allows the surgeon to expose the elbow circumferentially through one skin incision. This approach has been associated with fewer wound complications and has allowed immediate active motion of the elbow.

An overview of distal radial fractures

Fractures of the distal radius include a wide spectrum of fracture patterns. As well as involving the distal radius, these injuries can involve the wrist, the distal radio-ulnar joint and the distal ulna. The management of these injuries is consequently diverse, ranging from a plaster cast to advanced surgery. The principles of treatment are to reduce and maintain the reduction by restoring the radial height, volar tilt and intra-articular step. The acceptable reduction is to have radial height to within 2 mm of the ulnar, volar tilt greater than 0 degree and intra-articular step less than 1 mm. The present paper reviews the current concepts in the diagnosis, management and complications of distal radial fractures.

Arthroscopic relationship of the axillary nerve to the shoulder joint capsule: an anatomic study

Twelve right shoulders in fresh cadavers were dissected to determine the relation of the axillary nerve to the shoulder capsule and glenoid. Needles transfixed the nerve to the capsule and into the shoulder joint. Arthroscopy was performed to determine the location of the needles on the glenoid clock. The needles were then removed and the position of the shoulder changed to determine the effect on the position of the axillary nerve. The axillary nerve was held to the shoulder capsule with loose areolar tissue in the zone between 5 and 7 o'clock and was close to the glenoid in the neutral position, in extension, and in internal rotation. With shoulder abduction, external rotation, and perpendicular traction, the capsule became taut and the axillary nerve moved away from the glenoid. Abduction, external rotation, and perpendicular traction increase the zone of safety during arthroscopic anteroinferior capsulotomy adjacent to the glenoid between the 5 and 7 o'clock positions.

Dynamic external fixation for injuries of the proximal interphalangeal joint

Pain, stiffness, instability and degenerative arthritis are common sequelae of complex fracture-dislocations of the proximal interphalangeal (PIP) joint. Operations were carried out to obtain stability, followed by application of a dynamic external fixator in 20 patients with a mean age of 29 years. This provided stability and distraction, and allowed controlled passive movement. Most (70%) of the patients had a chronic lesion and the mean time from injury to surgery was 215 days (3 to 1953). The final mean range of movement was 12 to 86 degrees. Complications included redislocation and septic arthritis, which affected the outcome. Four pin-track infections and two breakages of the hinge did not influence the result. The PIP Compass hinge is a useful adjunct to surgical reconstruction of the injured PIP joint.

Charcot restraint orthotic walker

Five patients (three with insulin dependent diabetes mellitus (IDDM), one with noninsulin dependent diabetes mettlitus (NIDDM), and one with hereditary sensorimotor neuropathy (HSMN)) with stage 1 Charcot's neuroarthropathy involving the midfoot and or subtalar and ankle joints were fitted with a Charcot restraint orthotic walker (CROW). The rationale for this orthotic management was to maintain a plantigrade foot for ambulation and to protect the joints and skin by the uniform transfer or distribution of weight over the foot until the time when the pathology reached the stage of coalescence. The patients were able to fully bear weight and to ambulate with the CROW. All patients noted varying measures of improvement in symptoms and function at an average 12-month follow-up. The CROW is a useful orthosis in the armamentarium for treating neuroarthropathy of the pedal joints.

The dynamic elbow suspension splint

Elevation of the upper extremity after elbow surgery has rarely been advocated and can be difficult to achieve. Usually the extremity is elevated with the elbow at 90 degrees of flexion, so that swelling from the hand drains to the elbow but the elbow remains dependent. Excessive swelling causes discomfort and compromised wound healing, makes early mobilization difficult, and predisposes to joint contracture. We report on a dynamic elbow suspension splint, which is analogous to the Thomas splint used for femoral shaft fractures. The arm is held in full extension with an above-elbow plaster slab and is secured to the Thomas splint with skin traction. The splint is suspended on a Balkan frame at an angle of 60 degrees. We prefer to use the new Zimmer Thomas splint, because it is radiolucent and has self-adhesive sheep-skin supports that can be simply applied. It allows the patient to mobilize in bed and is well tolerated by patients and nursing staff. The dynamic elbow suspension splint is a useful adjunct after complex elbow surgery or trauma, because it reduces swelling and maintains the elbow in extension.

Operative fluoroscopy in hand and upper limb surgery. One hundred cases

We reviewed the use of a low radiation portable fluoroscopy unit in 100 patients. The most common indication was closed reduction of distal radial fractures. Fracture and joint stability were assessed on the real-time monitor and stored on videotape. Static images were stored on thermographic paper. Fluoroscopically guided joint injections and localization of implants, foreign bodies and bone tumours were performed. Fluoroscopy is a useful adjunct to arthroscopic assisted fracture reduction and other arthroscopic procedures such as distal ulnar resection. These new generation units produce superior resolution images, are easy to manoeuvre and do not require a radiographer.

The effect of vitamin A deficiency in rabbits on the elastic properties of the lung and thoracic aorta

Weanling rabbits were fed a vitamin A deficient diet for 6 weeks. During this period they failed to gain weight normally and exhibited significantly lower serum vitamin A levels when compared with their littermates fed a vitamin A supplemented diet. These findings indicated that vitamin A deficiency was established, and the lungs and specimens of aorta were removed for study. The pressure–volume relationships of saline-filled lungs revealed that test lungs were more compliant than control lungs and this difference was associated with a decrease in elastin content in test lungs. The absence of such changes in pair-fed controls suggests that the effects are due to vitamin A deficiency per se rather than the general effects of retarded growth. A decrease was also noted in the elastance of the aorta, confirming that vitamin A deficiency has an effect on elasticity of tissues generally. When vitamin A deficient animals were given vitamin A supplemented diets the elastance of the aorta returned to control values but the compliance of the lung, although somewhat decreased, did not reach control values. The mechanism by which vitamin A deficiency affects tissue elasticity is not known.