Quantitative assessment of multiple pathogen exposure and immune dynamics at scale.

IMPORTANCE: Serology reveals exposure to pathogens, as well as the state of autoimmune and other clinical conditions. It is used to evaluate individuals and their histories and as a public health tool to track epidemics. Employing a variety of formats, studies nearly always perform serology by testing response to only one or a few antigens. However, clinical outcomes of new infections also depend on which previous infections may have occurred. We developed a high-throughput serology method that evaluates responses to hundreds of antigens simultaneously. It can be used to evaluate thousands of samples at a time and provide a quantitative readout. This tool will enable doctors to monitor which pathogens an individual has been exposed to and how that changes in the future. Moreover, public health officials could track populations and look for infectious trends among large populations. Testing many potential antigens at a time may also aid in vaccine development.

Infectious Diseases Associated With Organized Sports and Outbreak Control.

Participation in organized sports has a variety of health benefits but also has the potential to expose the athlete to a variety of infectious diseases, some of which may produce outbreaks. Major risk factors for infection include skin-to-skin contact with athletes who have active skin infections, environmental exposures and physical trauma, and sharing of equipment and contact with contaminated fomites. Close contact that is intrinsic to team sports and psychosocial factors associated with adolescence are additional risks. Minimizing risk requires leadership by the organized sports community (including the athlete's primary care provider) and depends on outlining key hygiene behaviors, recognition, diagnosis, and treatment of common sports-related infections, and the implementation of preventive interventions.

Gap Junctions Contribute to Ictal/Interictal Genesis in Human Hypothalamic Hamartomas.

Human hypothalamic hamartoma (HH) is a rare subcortical lesion associated with treatment-resistant epilepsy. Cellular mechanisms responsible for epileptogenesis are unknown. We hypothesized that neuronal gap junctions contribute to epileptogenesis through synchronous activity within the neuron networks in HH tissue. We studied surgically resected HH tissue with Western-blot analysis, immunohistochemistry, electron microscopy, biocytin microinjection of recorded HH neurons, and microelectrode patch clamp recordings with and without pharmacological blockade of gap junctions. Normal human hypothalamus tissue was used as a control. Western blots showed increased expression of both connexin-36 (Cx36) and connexin-43 (Cx43) in HH tissue compared with normal human mammillary body tissue. Immunohistochemistry demonstrated that Cx36 and Cx43 are expressed in HH tissue, but Cx36 was mainly expressed within neuron clusters while Cx43 was mainly expressed outside of neuron clusters. Gap-junction profiles were observed between small HH neurons with electron microscopy. Biocytin injection into single recorded small HH neurons showed labeling of adjacent neurons, which was not observed in the presence of a neuronal gap-junction blocker, mefloquine. Microelectrode field recordings from freshly resected HH slices demonstrated spontaneous ictal/interictal-like discharges in most slices. Bath-application of gap-junction blockers significantly reduced ictal/interictal-like discharges in a concentration-dependent manner, while not affecting the action-potential firing of small gamma-aminobutyric acid (GABA) neurons observed with whole-cell patch-clamp recordings from the same patient's HH tissue. These results suggest that neuronal gap junctions between small GABAergic HH neurons participate in the genesis of epileptic-like discharges. Blockade of gap junctions may be a new therapeutic strategy for controlling seizure activity in HH patients.

Hypothalamic hamartomas: neuropathological features with and without prior gamma knife radiosurgery.

BACKGROUND: The neuropathological consequences of Gamma Knife radiosurgery (GK) on hypothalamic hamartoma (HH) are unknown. OBJECTIVE: In a cohort of patients undergoing surgery for treatment-resistant epilepsy, we compared surgically resected HH tissue from patients without (group I; n = 19) and with (group II; n = 10) a history of GK (median dose 16 Gy to the 50% isodose margin). METHODS: Techniques included thick-section stereology for total nucleated and total neuron cell counts, and thin-section immunohistochemistry. Normal human hypothalamus derived from age-matched autopsy material was used as control tissue for CD68 immunohistochemistry. Qualitative scoring of tissue sections was performed by a neuropathologist who was blind to the GK treatment history. RESULTS: GK is associated with decreased total cell density (p < 0.02). A dose-dependent association of GK with decreased total neuron density approached significance (p = 0.06). Group II HH tissue had significantly more (1) reactive gliosis, (2) thickened capillary endothelium and (3) microglial activation. Degenerative features, including karyorrhexis and pyknotic nuclei, were infrequent in group II and absent in group I HH tissue. CONCLUSIONS: Nonnecrotizing doses of GK radiosurgery decrease cell density in human HH tissue. Cell loss resulting from GK may contribute to decreased excitation in the neuronal networks responsible for seizure onset in HH tissue.

Baseball and softball.

Baseball and softball are among the most popular and safest sports in which children and adolescents participate. Nevertheless, traumatic and overuse injuries occur regularly, including occasional catastrophic injury and even death. Safety of the athlete is a constant focus of attention among those responsible for modifying rules. Understanding the stresses placed on the arm, especially while pitching, led to the institution of rules controlling the quantity of pitches thrown in youth baseball and established rest periods between pitching assignments. Similarly, field maintenance and awareness of environmental conditions as well as equipment maintenance and creative prevention strategies are critically important in minimizing the risk of injury. This statement serves as a basis for encouraging safe participation in baseball and softball. This statement has been endorsed by the Canadian Paediatric Society.

Policy statement­Climatic heat stress and exercising children and adolescents.

Results of new research indicate that, contrary to previous thinking, youth do not have less effective thermoregulatory ability, insufficient cardiovascular capacity, or lower physical exertion tolerance compared with adults during exercise in the heat when adequate hydration is maintained. Accordingly, besides poor hydration status, the primary determinants of reduced performance and exertional heat-illness risk in youth during sports and other physical activities in a hot environment include undue physical exertion, insufficient recovery between repeated exercise bouts or closely scheduled same-day training sessions or rounds of sports competition, and inappropriately wearing clothing, uniforms, and protective equipment that play a role in excessive heat retention. Because these known contributing risk factors are modifiable, exertional heat illness is usually preventable. With appropriate preparation, modifications, and monitoring, most healthy children and adolescents can safely participate in outdoor sports and other physical activities through a wide range of challenging warm to hot climatic conditions.

Autosomal recessive spastic ataxia of Charlevoix-Saguenay: compound heterozygotes for nonsense mutations of the SACS gene.

Mutations of the SACS gene have been reported in patients with autosomal recessive spastic ataxia of Charlevoix-Saguenay from Canada (Quebec), Tunisia, Japan, Turkey, Belgium, Italy, Spain, the Netherlands, and Germany. Features that distinguish autosomal recessive spastic ataxia of Charlevoix-Saguenay from other recessive ataxias include sensory motor polyneuropathy and hypermyelinated retinal nerve fibers. We describe the clinical, electrophysiological, and radiological features in 2 white American siblings diagnosed with autosomal recessive spastic ataxia of Charlevoix-Saguenay. The 2 affected children are compound heterozygotes for nonsense mutations of the SACS gene (c. 3484 G>T, p. E 1162 X; and c. 11,707 C>T, p. R 3903 X). We have measured allele-specific SACS mRNA abundance in peripheral blood and show that these specific mutant mRNAs are not degraded. We suggest that in children with early onset cerebellar ataxia and spasticity, ophthalmological examination and nerve conduction testing may guide genetic testing.

Evidence for population variation in TSC1 and TSC2 gene expression.

BACKGROUND: Tuberous sclerosis complex (TSC) is an autosomal dominant neurogenetic disorder caused by mutations in one of two genes, TSC1 or TSC2, which encode the proteins hamartin and tuberin, respectively 123. Common features of TSC include intractable epilepsy, mental retardation, and autistic features. TSC is associated with specific brain lesions, including cortical tubers, subependymal nodules and subependymal giant cell astrocytomas. In addition, this disease frequently produces characteristic tumors, termed hamartomas, in the kidneys, heart, skin, retina, and lungs. Disease severity in TSC can be quite variable and is not determined by the primary mutation alone. In fact, there is often considerable variability in phenotype within single families, where all affected individuals carry the same mutation. Factors suspected to influence phenotype in TSC include the specific primary mutation, random occurrence of second-hit somatic mutations, mosaicism, "modifying genes", and environmental factors. In addition to these factors, we hypothesize that differences in mRNA expression from the non-mutated TSC allele, or possibly from the mutated allele, play a part in modifying disease severity. Common genetic variants that regulate mRNA expression have previously been shown to play important roles in human phenotypic variability, including disease susceptibility. A prediction based on this idea is that common regulatory variants that influence disease severity in TSC should be detectable in non-affected individuals. METHODS: A PCR/primer extension assay was used to measure allele specific expression of TSC1 and TSC2 mRNAs in leukocytes isolated from normal volunteers. This assay can be used to measure "allelic expression imbalance" (AEI) in individuals by making use of heterozygous "marker" single nucleotide polymorphisms (SNPs) located within their mRNA. RESULTS: In this study we show for the first time that TSC1 and TSC2 genes exhibit allele-specific differences in mRNA expression in blood leukocytes isolated from normal individuals. CONCLUSIONS: These results support the possibility that allele-specific variation in TSC mRNA expression contributes to the variable severity of symptoms in TSC patients.

Athletic participation by children and adolescents who have systemic hypertension.

Children and adolescents who have hypertension may be at risk for complications when exercise causes their blood pressure to rise even higher. The purpose of this statement is to update recommendations concerning the athletic participation of individuals with hypertension, including special populations such as those with spinal cord injuries or obesity, by using the guidelines from "The 36th Bethesda Conference: Eligibility Recommendations for Competitive Athletes with Cardiovascular Abnormalities"; "The Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents"; and "The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure."

Abnormalities of cell packing density and dendritic complexity in the MeCP2 A140V mouse model of Rett syndrome/X-linked mental retardation.

BACKGROUND: Rett syndrome (RTT), a common cause of mental retardation in girls, is associated with mutations in the MECP2 gene. Most human cases of MECP2 mutation in girls result in classical or variant forms of RTT. When these same mutations occur in males, they often present as severe neonatal encephalopathy. However, some MECP2 mutations can also lead to diseases characterized as mental retardation syndromes, particularly in boys. One of these mutations, A140V, is a common, recurring missense mutation accounting for about 0.6% of all MeCP2 mutations and ranking 21st by frequency. It has been described in familial X-linked mental retardation (XLMR), PPM- X syndrome (Parkinsonism, Pyramidal signs, Macroorchidism, X-linked mental retardation) and in other neuropsychiatric syndromes. Interestingly, this mutation has been reported to preserve the methyl-CpG binding function of the MeCP2 protein while compromising its ability to bind to the mental retardation associated protein ATRX. RESULTS: We report the construction and initial characterization of a mouse model expressing the A140V MeCP2 mutation. These initial descriptive studies in male hemizygous mice have revealed brain abnormalities seen in both RTT and mental retardation. The abnormalities found include increases in cell packing density in the brain and a significant reduction in the complexity of neuronal dendritic branching. In contrast to some MeCP2 mutation mouse models, the A140V mouse has an apparently normal lifespan and normal weight gain patterns with no obvious seizures, tremors, breathing difficulties or kyphosis. CONCLUSION: We have identified various neurological abnormalities in this mouse model of Rett syndrome/X-linked mental retardation which may help to elucidate the manner in which MECP2 mutations cause neuronal changes resulting in mental retardation without the confounding effects of seizures, chronic hypoventilation, or other Rett syndrome associated symptoms.

Medical conditions affecting sports participation.

Children and adolescents with medical conditions present special issues with respect to participation in athletic activities. The pediatrician can play an important role in determining whether a child with a health condition should participate in certain sports by assessing the child's health status, suggesting appropriate equipment or modifications of sports to decrease the risk of injury, and educating the athlete, parent(s) or guardian, and coach regarding the risks of injury as they relate to the child's condition. This report updates a previous policy statement and provides information for pediatricians on sports participation for children and adolescents with medical conditions.

Neuropathological and immunochemical studies of brain parenchyma in acetylcholinesterase knockout mice: implications in Alzheimer's disease.

The 'cholinergic hypothesis', based on the correlation of the reduction of cholinergic activity in Alzheimer's disease (AD) with cognition and memory, is currently the most widely-held view for AD. Drug treatments for AD focus mainly on inhibition of acetylcholinesterase (AChE), and to some extent butyrylcholinesterase (BChE). In addition to changes in AChE in AD, there is a rise in the level of the sister enzyme BChE. However, the role of the two cholinesterases is poorly understood in vivo. We characterized several proteins immunohistochemically in brain sections from AChE nullizygote (AChE-/-) and wild type AChE+/+ mice. Previous studies had shown that AChE-/- mouse tissues are devoid of AChE activity and that the overall cholinesterase activity is significantly decreased in the knockout group [16]. Despite the differences of cholinesterase activity, we found no significant structural alterations between the experimental groups. Immunohistochemical examination revealed no neuronal, dendritic, astrocytic, synaptic, microglial, and endothelial differences between AChE-/- and AChE+/+ mice. Similarly, the histochemical examination showed no morphologic alterations between AChE-/- and AChE+/+ mice. Our studies show that neither the absence of AChE nor the presence exclusively of BChE is associated with neuroglial and vascular pathology.

Quadriceps angle and risk of injury among high school cross-country runners.

DESIGN: Prospective cohort study. OBJECTIVES: To determine the relationship between quadriceps angle (Q-angle) and risk of lower extremity injury among adolescent cross-country runners. BACKGROUND: No consensus exists on the role of the Q-angle as a risk factor for lower-extremity overuse injury, especially the effect of large Q-angle or right-left Q-angle difference. METHODS AND MEASURES: The Q-angles of 393 high school cross-country runners, 13 to 19 years of age, were goniometrically measured in a static, standing position with quadriceps relaxed. The runners were followed during a cross-country season to assess lower extremity injuries resulting from running in practices or competitions. RESULTS: Runners with a Q-angle >20 degrees were at 1.7 times greater risk of injury (relative risk [RR], 1.7; 95% confidence interval [CI]: 1.2, 2.4) compared with runners whose Q-angle was 10 degrees to <15 degrees . The RR estimates were similar among girls and boys. Runners with >4 degrees absolute right-left Q-angle difference were at 1.8 times greater risk (RR, 1.8; 95% CI: 1.4, 2.5) compared to runners with a smaller difference. Runners with a Q-angle >20 degrees were more likely to injure their knee, while runners with >4 degrees Q-angle difference were more likely to injure their shin. Runners with a Q-angle >20 degrees had greater time lost due to injury. CONCLUSIONS: High school cross-country runners with large or asymmetric Q-angles may be at greater risk for running injury. Our study suggests that Q-angle measurement be included in preseason screening exams.

Epidemiology of musculoskeletal injuries among high school cross-country runners.

To determine the incidence of lower-extremity injury among high school cross-country runners and to identify risk factors for injury, the authors prospectively monitored a cohort of 421 runners competing on 23 cross-country teams in 12 Seattle, Washington, high schools during the 1996 cross-country season. Collected were daily injury and athletic exposure (AE) reports, a baseline questionnaire on prior running and injury experience, anthropometric measurements, and coaches' training logs. The overall incidence rate of injury was 17.0/1,000 AEs. Girls had a significantly higher overall injury rate (19.6/1,000 AEs) than boys did (15.0/1,000 AEs) (incidence rate ratio = 1.3, 95% confidence interval: 1.0, 1.6). Compared with boys, girls had significantly higher rates of injuries resulting in >or=15 days of disability. For the overall sample and for girls, Cox regression revealed that a quadriceps angle of >or=20 degrees and an injury during summer running prior to the season were the most important predictors of injury. For boys, a quadriceps angle of >or=15 degrees and a history of multiple running injuries were most associated with injury. Results suggest that the incidence of lower-extremity injuries is high for cross-country runners, especially girls. Preseason screening to determine risk factors should be examined as a preventive approach for identifying high-risk runners.

Hepatic lipase deficiency attenuates mouse ovarian progesterone production leading to decreased ovulation and reduced litter size.

The lipolytic enzyme hepatic lipase (HL) may facilitate mobilization of cholesterol substrate for ovarian steroidogenesis. We investigated whether HL was necessary for optimum reproduction in the female mouse by analyzing breeding performance and ovarian responses to gonadotropins in HL-/- mice. HL-/- female mice bred with HL-/- males had the same pregnancy success rate and pup survival rate as did wild-type (WT) mice but had significantly smaller litters, producing 1.7 fewer pups per litter. Mice were primed with eCG/hCG, and at 6 h post-hCG the HL-/- mice had smaller ovaries than did the WT mice. HL deficiency specifically affected ovarian weight; adrenal gland weights did not differ between WT and HL-/- mice. HL-/- mice weighed more than age-matched WT mice. Between the two mouse genotypes, uterine weights were the same, indicating that estrogen production was equivalent. However, the HL-/- ovaries produced significantly less progesterone than did the WT ovaries within 6 h of hCG stimulation. HL-/- ovaries had the same number of large antral follicles as did the WT ovaries but had fewer hemorrhagic sites, which represent ovulations, fewer corpora lutea, and more oocytes trapped in corpora lutea. We suggest that reduced progesterone synthesis following hCG stimulation attenuated the final maturation of preovulatory follicles, resulting in smaller ovaries. Furthermore, reduced progesterone production limited the expression of proteolytic enzymes needed for tissue remodeling, resulting in fewer ovulations with a corresponding increase in trapped or unovulated oocytes and providing a possible explanation for the smaller litter size observed in spontaneously ovulating HL-/- mice.