Indications for epilepsy monitoring in pediatric and adolescent health care.

Seizures present in childhood with infinite diversity. History alone may suffice for diagnosis in some cases; more often additional evidence is needed to clarify events of concern. Electroencephalography (EEG) is a primary methodology used for seizure identification and management. Pediatric and adolescent health care providers are increasingly asked to make decisions about when and how to refer patients for eventual monitoring and must then be able to confidently interpret any resulting report(s). Comprehensive literature review was undertaken to provide a succinct and up-to-date overview aimed at general and subspecialty non-neurologist pediatric and adolescent health care providers to not only convey a solid general understanding of EEG and what it entails for patients and their families, but also foster a deeper understanding of the indications for monitoring-and how to interpret documented findings. In plain language this resultant guide reviews EEG basics, provides a crash course in the various types of EEG available, discusses broad indications for epilepsy monitoring, guides counseling and management for patients and their families both before and after EEG, and ultimately aids in the interpretation of both findings and prognosis. This review should allow both primary and subspecialty non-neurologic pediatric and adolescent health care providers to better identify when and how to best utilize EEG as part of a larger comprehensive clinical approach, distinguishing and managing both epileptic and nonepileptic disorders of concern while fostering communication across providers to facilitate and coordinate better holistic long-term care of pediatric and adolescent patients.

Nocturnal events in children: When and how to evaluate.

Nocturnal events of wide variety and concern are frequently reported by patients and their caregivers. To evaluate suspected abnormal events, primary care physicians must first be familiar with normal behaviors, movements and breathing patterns. Abnormal nocturnal events can then be categorized as nocturnal seizure, parasomnia, sleep-related movement disorder or sleep-related breathing disorder. Diagnoses in the above categories can be made clinically; however, it is important to know when to refer for additional evaluation. Comprehensive literature review was undertaken of nocturnal and sleep-related disorders. This guide reviews nocturnal seizures, normal and abnormal nonepileptic movements and behaviors, discusses broad indications for referral for electroencephalography (EEG) or polysomnography (PSG), and guides counseling and management for patients and their families, ultimately aiding in interpretation of both findings and prognosis. Epilepsy syndromes can result in seizures during sleep or adjacent periods of wakefulness. Parasomnias and sleep-related movement disorders tend to also occur in childhood and may be distinguished clinically. Referral to additional specialists for specific studies including EEG or PSG can be necessary, while other times a knowledgeable and vigilant clinician can contribute to a prompt diagnosis based on clinical features. Nocturnal events often can be managed with parental reassurance and watchful waiting, but treatment or evaluation may be needed. Sleep-related breathing disorders are important to recognize as they present very differently in children than in adults and early intervention can be life-saving. This review should allow both primary and subspecialty non-neurologic pediatric and adolescent health care providers to better utilize EEG and PSG as part of a larger comprehensive clinical approach, distinguishing and managing both epileptic and nonepileptic nocturnal disorders of concern while fostering communication across providers to facilitate and coordinate better holistic long-term care of pediatric and adolescent patients.

Development trends for human monoclonal antibody therapeutics.

Fully human monoclonal antibodies (mAbs) are a promising and rapidly growing category of targeted therapeutic agents. The first such agents were developed during the 1980s, but none achieved clinical or commercial success. Advances in technology to generate the molecules for study - in particular, transgenic mice and yeast or phage display - renewed interest in the development of human mAbs during the 1990s. In 2002, adalimumab became the first human mAb to be approved by the US Food and Drug Administration (FDA). Since then, an additional six human mAbs have received FDA approval: panitumumab, golimumab, canakinumab, ustekinumab, ofatumumab and denosumab. In addition, 3 candidates (raxibacumab, belimumab and ipilimumab) are currently under review by the FDA, 7 are in Phase III studies and 81 are in either Phase I or II studies. Here, we analyse data on 147 human mAbs that have entered clinical study to highlight trends in their development and approval, which may help inform future studies of this class of therapeutic agents.

Antibody fragments: hope and hype.

The antibody molecule is modular and separate domains can be extracted through biochemical or genetic means. It is clear from review of the literature that a wave of novel, antigen-specific molecular forms may soon enter clinical evaluation. This report examines the developmental histories of therapeutics derived from antigen-specific fragments of antibodies produced by recombinant processes. Three general types of fragments were observed, antigen-binding fragments (Fab), single chain variable fragments (scFv) and "third generation" (3G), each representing a successive wave of antibody fragment technology. In parallel, drug developers have explored multi-specificity and conjugation with exogenous functional moieties in all three fragment types. Despite high hopes and an active pipeline, enthusiasm for differentiating performance of fragments should, perhaps, be tempered as there are yet few data that suggest these molecules have distinct clinical properties due only to their size.

Much cheaper, almost as good: decrementally cost-effective medical innovation.

Under conditions of constrained resources, cost-saving innovations may improve overall outcomes, even when they are slightly less effective than available options, by permitting more efficient reallocation of resources. The authors systematically reviewed all MEDLINE-cited cost-utility analyses written in English from 2002 to 2007 to identify and describe cost- and quality-decreasing medical innovations that might offer favorable "decrementally" cost-effective tradeoffs-defined as saving at least $100 000 per quality-adjusted life-year lost. Of 2128 cost-effectiveness ratios from 887 publications, only 9 comparisons (0.4% of total) described 8 innovations that were deemed to be decrementally cost-effective. Examples included percutaneous coronary intervention (instead of coronary artery bypass graft) for multivessel coronary disease, repetitive transcranial magnetic stimulation (instead of electroconvulsive therapy) for drug-resistant major depression, watchful waiting for inguinal hernias, and hemodialyzer sterilization and reuse. On a per-patient basis, these innovations yielded savings from $122 to almost $12 000 but losses of 0.001 to 0.021 quality-adjusted life-years (approximately 8 hours to 1 week). These findings demonstrate the rarity of decrementally cost-effective innovations in the medical literature.

Hepatic portal venous gas: the ABCs of management.

OBJECTIVE: To review the use of computed tomography (CT) and radiography in managing hepatic portal venous gas (HPVG) at a university-affiliated tertiary care center and in the literature. Hepatic portal venous gas is frequently associated with acute mesenteric ischemia, accounting for most of the HPVG-associated mortality. While early studies were necessarily dependent on plain abdominal radiography, modern high-resolution CT has revealed a host of benign conditions in which HPVG has been reported that do not require emergent surgery. DATA SOURCES: Patient records from our institution over the last 10 years and relevant studies from BioMed Central, CENTRAL, PubMed, and PubMed Central. In addition, references cited in selected works were also used as source data. STUDY SELECTION: Patient records were selected if the CT or radiograph findings matched the term hepatic portal venous gas. Studies were selected based on the search terms hepatic portal venous gas or portal venous gas. DATA EXTRACTION: Quantitative and qualitative data were quoted directly from cited work. DATA SYNTHESIS: Early studies of HPVG were based on plain abdominal radiography and a literature survey in 1978 found an associated mortality rate of 75%, primarily due to ischemic bowel disease. Modern abdominal CT has resulted in the detection of HPVG in more benign conditions, and a second literature survey in 2001 found a total mortality of only 39%. While the pathophysiology of HPVG is, as yet, unclear, changing abdominal imaging technology has altered the significance of this radiologic finding. Hepatic portal venous gas therefore predicts high risk of mortality (>50%) if detected by plain radiography or by CT in a patient with additional evidence of necrotic bowel. If detected by CT in patients after surgical or endoscopic manipulation, the clinician is advised that there is no evidence of increased risk. If HPVG is detected by CT in patients with active peptic ulcer disease, intestinal obstruction and/or dilatation, or mucosal diseases such as Crohn disease or ulcerative colitis, caution is warranted, as risk of death may approach 20% to 30%. CONCLUSION: The finding of HPVG alone cannot be an indication for emergency exploration, and we have developed an evidence-based algorithm to guide the clinician in management of patients with HPVG.

Sortase-mediated assembly and surface topology of adhesive pneumococcal pili.

The rlrA genetic islet encodes an extracellular pilus in the Gram-positive pathogen Streptococcus pneumoniae. Of the three genes for structural subunits, rrgB encodes the major pilin, while rrgA and rrgC encode ancillary pilin subunits decorating the pilus shaft and tip. Deletion of all three pilus-associated sortase genes, srtB, srtC and srtD, completely prevents pilus biogenesis. Expression of srtB alone is sufficient to covalently associate RrgB subunits to one another as well as linking the RrgA adhesin and the RrgC subunit into the polymer. The active-site cysteine residue of SrtB (Cys 177) is crucial for incorporating RrgC, even when the two other sortase genes are expressed. SrtC is redundant to SrtB in permitting RrgB polymerization, and in linking RrgA to the RrgB filament, but SrtC is insufficient to incorporate RrgC. In contrast, expression of srtD alone fails to mediate RrgB polymerization, and a srtD mutant assembles heterotrimeric pilus indistinguishable from wild type. Topological studies demonstrate that pilus antigens are localized to symmetric foci at the cell surface in the presence of all three sortases. This symmetric focal presentation is abrogated in the absence of either srtB or srtD, while deletion of srtC had no effect. In addition, strains expressing srtB alone or srtC alone also displayed disrupted antigen localization, despite polymerizing subunits. Our data suggest that both SrtB and SrtC act as pilus subunit polymerases, with SrtB processing all three pilus subunit proteins, while SrtC only RrgB and RrgA. In contrast, SrtD does not act as a pilus subunit polymerase, but instead is required for wild-type focal presentation of the pilus at the cell surface.

Interleukin-8 secretion in response to aferric enterobactin is potentiated by siderocalin.

Siderophores are low-molecular-weight iron chelators secreted by microbes to obtain iron under deprivation. We hypothesized that the catecholate siderophore enterobactin, produced by Enterobacteriaceae, serves as a proinflammatory signal for respiratory epithelial cells. Respiratory tract responses were explored, since at this site siderocalin, an enterobactin-binding mammalian gene product, is expressed inducibly at high levels and enterobactin-secreting respiratory flora is rare, suggesting selection against a dependence on enterobactin. Addition of aferric, but not iron-saturated, enterobactin elicits a dose-dependent increase in secretion of the proinflammatory chemokine interleukin-8 by human respiratory epithelial cells in culture. This response to purified enterobactin is potentiated by recombinant siderocalin at physiologically relevant concentrations. Conditioned media from genetically modified Escherichia coli strains expressing various levels of enterobactin induce an enterobactin-mediated proinflammatory response. Siderocalin has been shown to deliver enterobactin to other mammalian cell types, exogenously supplied siderocalin can be detected within epithelial cells, and siderocalin increases delivery of enterobactin to the intracellular compartment. Although many siderophores perturb labile cellular iron pools, only enterobactin elicits interleukin-8 secretion, suggesting that iron chelation is necessary but not sufficient. Thus, aferric enterobactin may be a proinflammatory signal for respiratory epithelial cells, permitting detection of microbial communities that have disturbed local iron homeostasis, and siderocalin expression by the host amplifies this signal. This may be a novel mechanism for the mucosa to respond to metabolic signals of expanding microbial communities.

Capsule enhances pneumococcal colonization by limiting mucus-mediated clearance.

Expression of a polysaccharide capsule is required for the full pathogenicity of many mucosal pathogens such as Streptococcus pneumoniae. Although capsule allows for evasion of opsonization and subsequent phagocytosis during invasive infection, its role during mucosal colonization, the organism's commensal state, remains unknown. Using a mouse model, we demonstrate that unencapsulated mutants remain capable of nasal colonization but at a reduced density and duration compared to those of their encapsulated parent strains. This deficit in colonization was not due to increased susceptibility to opsonophagocytic clearance involving complement, antibody, or the influx of Ly-6G-positive cells, including neutrophils seen during carriage. Rather, unencapsulated mutants remain agglutinated within lumenal mucus and, thus, are less likely to transit to the epithelial surface where stable colonization occurs. Studies of in vitro binding to immobilized human airway mucus confirmed the inhibitory effect of encapsulation. Likewise, pneumococcal variants expressing larger amounts of negatively charged capsule per cell were less likely to adhere to surfaces coated with human mucus and more likely to evade initial clearance in vivo. Removal of negatively charged sialic acid residues by pretreatment of mucus with neuraminidase diminished the antiadhesive effect of encapsulation. This suggests that the inhibitory effect of encapsulation on mucus binding may be mediated by electrostatic repulsion and offers an explanation for the predominance of anionic polysaccharides among the diverse array of unique capsule types. In conclusion, our findings demonstrate that capsule confers an advantage to mucosal pathogens distinct from its role in inhibition of opsonophagocytosis--escape from entrapment in lumenal mucus.

Epithelial cells are sensitive detectors of bacterial pore-forming toxins.

Epithelial cells act as an interface between human mucosal surfaces and the surrounding environment. As a result, they are responsible for the initiation of local immune responses, which may be crucial for prevention of invasive infection. Here we show that epithelial cells detect the presence of bacterial pore-forming toxins (including pneumolysin from Streptococcus pneumoniae, alpha-hemolysin from Staphylococcus aureus, streptolysin O from Streptococcus pyogenes, and anthrolysin O from Bacillus anthracis) at nanomolar concentrations, far below those required to cause cytolysis. Phosphorylation of p38 MAPK appears to be a conserved response of epithelial cells to subcytolytic concentrations of bacterial poreforming toxins, and this activity is inhibited by the addition of high molecular weight osmolytes to the extracellular medium. By sensing osmotic stress caused by the insertion of a sublethal number of pores into their membranes, epithelial cells may act as an early warning system to commence an immune response, while the local density of toxin-producing bacteria remains low. Osmosensing may thus represent a novel innate immune response to a common bacterial virulence strategy.

The role of innate immune responses in the outcome of interspecies competition for colonization of mucosal surfaces.

Since mucosal surfaces may be simultaneously colonized by multiple species, the success of an organism may be determined by its ability to compete with co-inhabitants of its niche. To explore the contribution of host factors to polymicrobial competition, a murine model was used to study the initiation of colonization by Haemophilus influenzae and Streptococcus pneumoniae. Both bacterial species, which occupy a similar microenvironment within the nasopharynx, persisted during colonization when given individually. Co-colonization, however, resulted in rapid clearance of S. pneumoniae from the upper respiratory tract, associated with increased recruitment of neutrophils into paranasal spaces. Systemic depletion of either neutrophil-like cells or complement was sufficient to eliminate this competitive effect, indicating that clearance was likely due to enhanced opsonophagocytic killing. The hypothesis that modulation of opsonophagocytic activity was responsible for host-mediated competition was tested using in vitro killing assays with elicited neutrophil-like cells. Components of H. influenzae (but not S. pneumoniae) stimulated complement-dependent phagocytic killing of S. pneumoniae. Thus, the recruitment and activation of neutrophils through selective microbial pattern recognition may underlie the H. influenzae-induced clearance of S. pneumoniae. This study demonstrates how innate immune responses may mediate competitive interactions between species and dictate the composition of the colonizing flora.

Bacterial colonization of nasal mucosa induces expression of siderocalin, an iron-sequestering component of innate immunity.

Host-microbe interactions often begin with colonization of mucosal surfaces. These relationships are highly specific, as certain microbial species are found only in particular microenvironments. Transcriptional microarrays were used to screen host genes whose expression in the murine nasal mucosa was affected by colonization with the Gram-positive bacterium Streptococcus pneumoniae. Siderocalin (Scn, or lipocalin 2 or neutrophil gelatinase-associated lipocalin) expression was increased up to 65-fold during colonization by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). Western analysis showed that Scn was secreted into airway surface fluid in colonized animals. Immunohistochemical analysis localized Scn expression primarily to secretory Bowman's glands. Similar results were observed during colonization with the Gram-negative bacterium Haemophilus influenzae, suggesting that Scn secretion is a general response. Western analysis of human nasal secretions also demonstrated secretion of Scn at potentially bacteriostatic levels. This is a previously unrecognized response that may have a role in determining the establishment or maintenance of mucosal colonization. Scn contributes to antimicrobial defence by sequestration of a subset of microbial siderophores. As neither S. pneumoniae nor H. influenzae are known to produce or utilize siderophores, successful colonizers of the nasal passages may have evolved siderophore-independent mechanisms to acquire essential iron and to evade the inhibitory effects of Scn.

Female pheromones stimulate release of luteinizing hormone and testosterone without altering GnRH mRNA in adult male Syrian hamsters (Mesocricetus auratus).

In many species chemosensory stimuli function as important signals that influence reproductive status. Neurons synthesizing the peptide gonadotropin-releasing hormone (GnRH) are critical mediators of reproductive function via their regulation of the hypothalamic-pituitary-gonadal (HPG) axis, and they are thought to be responsive to chemosensory information. In the present study, we sought to elucidate the effects of female chemosensory stimuli on the HPG axis in sexually naive adult male Syrian hamsters. In Experiment 1, serial blood samples were collected from catheterized male hamsters following exposure to female pheromones in order to characterize the luteinizing hormone (LH) response to this chemosensory stimulus. In Experiment 2, brains and terminal blood samples were collected from animals 0, 60, and 120 min following pheromone exposure. GnRH mRNA was measured in brain tissue sections using in situ hybridization, and plasma concentrations of LH and testosterone were measured using radioimmunoassay. Data from Experiment 1 indicated that female pheromones elicited a rapid rise in plasma LH that peaked at 15 min and returned to baseline 45 min after exposure. In Experiment 2, testosterone was elevated in terminal blood samples obtained 60 min, but not 120 min, after exposure to pheromones. LH levels were unaffected at both of these time points. The chemosensory-induced increases in LH and testosterone release were not accompanied by subsequent changes in GnRH mRNA over the time course studied. These data suggest that while activation of the male HPG axis by female pheromones involves release of GnRH, it does not involve increases in GnRH mRNA 1-2 h after pheromonal stimulation as a mechanism for replenishment of released peptide.

Medulloblastoma tumorigenesis diverges from cerebellar granule cell differentiation in patched heterozygous mice.

Medulloblastoma is a cerebellar tumor that can arise through aberrant activation of Sonic hedgehog (Shh) signaling, which normally regulates cerebellar granule cell proliferation. Mutations of the Shh receptor PATCHED (PTCH) are associated with medulloblastomas, which have not been found to have loss of PTCH heterozygosity. We address whether patched (Ptc) heterozygosity fundamentally alters granule cell differentiation and contributes to tumorigenesis by increasing proliferation and/or decreasing apoptosis in Ptc+/- mice. Our data show that postnatal Ptc+/- mouse granule cell precursor growth is not globally altered. However, many older Ptc+/- mice display abnormal cerebellar regions containing persistently proliferating granule cell precursors. Since fewer Ptc+/- mice form medulloblastomas, these granule cell rests represent a developmentally disrupted, but uncommitted stage of tumorigenesis. Although Ptc+/- mouse medulloblastomas express neurodevelopmental genes, they diverge from granule cell differentiation in their discordant coexpression of postmitotic markers despite their ongoing growth. Like human medulloblastomas, mouse tumors with reduced levels of the neurotrophin-3 receptor, trkC/Ntrk3, display decreased apoptosis in vivo, illustrating the role of TrkC in regulating tumor cell survival. These results indicate that Ptc heterozygosity contributes to tumorigenesis by predisposing a subset of granule cell precursors to the formation of proliferative rests and subsequent dysregulation of developmental gene expression.

Testosterone, puberty, and the pattern of male aggression in Syrian hamsters.

The interaction between testosterone and pubertal development on aggression in the male Syrian hamster (Mesocricetus auratus) was examined in two experiments. First, gonad-intact prepubertal and adult male hamsters were tested for aggression using the resident-intruder paradigm with an age- and weight-matched intruder. Prepubertal males engaged in a greater number of attacks and had longer attack durations than adults. In the second experiment, prepubertal and adult males were castrated and treated with either a 0-, 2.5-, or 5-mg pellet of testosterone, and their aggression was assessed using the resident-intruder paradigm. Prepubertal males again showed shorter attack latencies and greater attack durations compared to adult males across all levels of testosterone. Testosterone treatment did not significantly affect these behaviors before or after pubertal development. We conclude that (a) pubertal development is associated with a decline in aggression in the male Syrian hamster, and (b) a developmental shift in behavioral sensitivity or responsiveness to testosterone does not underlie the pubertal decrease in aggression.

Magnetic resonance imaging of patched heterozygous and xenografted mouse brain tumors.

Experimental mouse models are emerging as useful systems for the study of human brain tumors. Nuclear magnetic resonance imaging (MRI) methods can noninvasively provide images of complex heterogeneous tissues such as experimental brain tumors. The current report demonstrates the feasibility of longitudinal high-resolution MRI in two mouse brain tumor models: patched heterozygous (ptc +/-) mice with spontaneously arising posterior fossa tumors that resemble human medulloblastoma, and homozygous nude mice implanted with intracerebral xenografts of human medulloblastoma cell lines. Methods were optimized to achieve favorable volumetric comparison with histologic methods and sub-millimeter resolution, improved by contrast enhancement with intravenous administration of a gadolinium-based agent. Results also show that experimental mice, even symptomatic mice, tolerate repeated serial imaging studies over weeks to months to follow tumor progression and to visualize placement of an intracerebral drug delivery system.