Cdk12 maintains the integrity of adult axons by suppressing actin remodeling

The role of cyclin-dependent kinases (CDKs) that are ubiquitously expressed in the adult nervous system remains unclear. Cdk12 is enriched in terminally differentiated neurons where its conical role in the cell cycle progression is redundant. We find that in adult neurons Cdk12 acts a negative regulator of actin formation, mitochondrial dynamics and neuronal physiology. Cdk12 maintains the size of the axon at sites proximal to the cell body through the transcription of homeostatic enzymes in the 1-carbon by folate pathway which utilize the amino acid homocysteine. Loss of Cdk12 leads to elevated homocysteine and in turn leads to uncontrolled F-actin formation and axonal swelling. Actin remodeling further induces Drp1-dependent fission of mitochondria and the breakdown of axon-soma filtration barrier allowing soma restricted cargos to enter the axon. We demonstrate that Cdk12 is also an essential gene for long-term neuronal survival and loss of this gene causes age-dependent neurodegeneration. Hyperhomocysteinemia, actin changes, and mitochondrial fragmentation are associated with several neurodegenerative conditions such as Alzheimer's disease and we provide a candidate molecular pathway to link together such pathological events.

Rapid Multiplexed Flow Cytometric Validation of CRISPRi sgRNAs in Tissue Culture

Genome-wide CRISPR-based screening is a powerful tool in forward genetics, enabling biologic discovery by linking a desired phenotype to a specific genetic perturbation. However, hits from a genome-wide screen require individual validation to reproduce and accurately quantify their effects outside of a pooled experiment. Here, we describe a step-by-step protocol to rapidly assess the effects of individual sgRNAs from CRISPR interference (CRISPRi) and CRISPR activation (CRISPRa) systems. All steps, including cloning, lentivirus generation, cell transduction, and phenotypic readout, can be performed entirely in 96-well plates. The system is highly flexible in both cell type and selection system, requiring only that the phenotype(s) of interest be read out via flow cytometry. We expect that this protocol will provide researchers with a rapid way to sift through potential screening hits, and prioritize them for deeper analysis in more complex in vitro or even in vivo systems. Graphical abstract.

Cold shock domain-containing protein E1 is a posttranscriptional regulator of the LDL receptor

The low-density lipoprotein receptor (LDLR) controls cellular delivery of cholesterol and clears LDL from the bloodstream, protecting against atherosclerotic heart disease, the leading cause of death in the United States. We therefore sought to identify regulators of the LDLR beyond the targets of current therapies and known causes of familial hypercholesterolemia. We found that cold shock domain-containing protein E1 (CSDE1) enhanced hepatic LDLR messenger RNA (mRNA) decay via its 3' untranslated region and regulated atherogenic lipoproteins in vivo. Using parallel phenotypic genome-wide CRISPR interference screens in a tissue culture model, we identified 40 specific regulators of the LDLR that were not previously identified by observational human genetic studies. Among these, we demonstrated that, in HepG2 cells, CSDE1 regulated the LDLR at least as strongly as statins and proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors. In addition, we showed that hepatic gene silencing of Csde1 treated diet-induced dyslipidemia in mice to a similar degree as Pcsk9 silencing. These results suggest the therapeutic potential of targeting CSDE1 to manipulate the posttranscriptional regulation of the LDLR mRNA for the prevention of cardiovascular disease. Our approach of modeling a clinically relevant phenotype in a forward genetic screen, followed by mechanistic pharmacologic dissection and in vivo validation, may serve as a generalizable template for the identification of therapeutic targets in other human disease states.

Concurrent Subcutaneous Panniculitis-like T-Cell Lymphoma and B-Cell Acute Lymphoblastic Leukemia in 2 Pediatric Patients

Subcutaneous panniculitis-like T-cell lymphoma is a cutaneous lymphoma characterized by CD8+ T-cell infiltrate in the subcutis that is rare in children. Acute lymphoblastic lymphoma is the most common pediatric malignancy and often presents with fevers and pancytopenia. Herein, we report 2 pediatric patients presenting with subcutaneous panniculitis-like T-cell lymphoma and B-cell acute lymphoblastic lymphoma, distinct hematologic malignancies arising from different lymphoid lineages, with no identifiable germline cancer predisposition.

Benzodiazepine exposures among women of reproductive age in the US, 2004-2018

Benzodiazepines, often used to treat anxiety, insomnia, and other conditions, are prescribed more frequently to women than men, and emergency department visits and overdose deaths involving benzodiazepines have increased significantly among women in recent years. This study describes characteristics and trends associated with benzodiazepine exposures among women of reproductive age (15-49 years old) that were reported to United States poison control centers from 2004 through 2018. The National Poison Data System recorded 258,370 first-ranked benzodiazepine exposures among women 15-49 years old during the study period. More than one-half (56.9%) of exposures involved a single-substance and one-third (34.0%) occurred among women 20-29 years old. The majority were categorized as "intentional, suspected suicide" (73.2%) or "intentional" (12.9%). Exposures frequently resulted in admission to a psychiatric facility (20.6%), critical care unit (18.1%), or non-critical care unit (9.3%). Twenty percent of cases resulted in a serious medical outcome, including 205 deaths. The substantial percentage of benzodiazepine exposures among women of reproductive age that were intentional and associated with suicide attempts or suicide deaths indicate that increased prevention efforts are needed to address this issue.

Ontogenetic allometry and architectural properties of the paravertebral and hindlimb musculature in Eastern cottontail rabbits (Sylvilagus floridanus): functional implications for developmental changes in locomotor performance

Due to small body size, an immature musculoskeletal system, and other growth-related limits on performance, juvenile mammals frequently experience a greater risk of predation than their adult counterparts. As a result, behaviorally precocious juveniles are hypothesized to exhibit musculoskeletal advantages that permit them to accelerate rapidly and evade predation. This hypothesis was tested through detailed quantitative evaluation of muscle growth in wild Eastern cottontail rabbits (Sylvilagus floridanus). Cottontail rabbits experience high rates of mortality during the first year of life, suggesting that selection might act to improve performance in growing juveniles. Therefore, it was predicted that muscle properties associated with force and power capacity should be enhanced in juvenile rabbits to facilitate enhanced locomotor performance. We quantified muscle architecture from 24 paravertebral and hindlimb muscles across ontogeny in a sample of n = 29 rabbits and evaluated the body mass scaling of muscle mass (MM), physiological cross-sectional area (PCSA), isometric force (Fmax ), and instantaneous power (Pinst ), along with several dimensionless architectural indices. In contrast to our hypothesis, MM and PCSA for most muscles change with positive allometry during growth by scaling at M b 1.3 and M b 1.1 , respectively, whereas Fmax and Pinst generally scale indistinguishably from isometry, as do the architectural indices tested. However, scaling patterns indicate that the digital flexors and ankle extensors of juvenile S. floridanus have greater capacities for force and power, respectively, than those in adults, suggesting these muscle properties may be a part of several compensatory features that promote enhanced acceleration performance in young rabbits. Overall, our study implies that body size constraints place larger, more mature rabbits at a disadvantage during acceleration, and that adults must develop hypertrophied muscles in order to maintain mechanical similarity in force and power capacities across development. These findings challenge the accepted understanding that juvenile animals are at a performance detriment relative to adults. Instead, for prey-predator interactions necessitating short intervals of high force and power generation relative to body mass, as demonstrated by rapid acceleration of cottontail rabbits fleeing predators, it may be the adults that struggle to keep pace with juveniles.

Repurposing tofacitinib as an anti-myeloma therapeutic to reverse growth-promoting effects of the bone marrow microenvironment

The myeloma bone marrow microenvironment promotes proliferation of malignant plasma cells and resistance to therapy. Activation of JAK/STAT signaling is thought to be a central component of these microenvironment-induced phenotypes. In a prior drug repurposing screen, we identified tofacitinib, a pan-JAK inhibitor Food and Drug Administration (FDA) approved for rheumatoid arthritis, as an agent that may reverse the tumor-stimulating effects of bone marrow mesenchymal stromal cells. Herein, we validated in vitro, in stromal-responsive human myeloma cell lines, and in vivo, in orthotopic disseminated xenograft models of myeloma, that tofacitinib showed efficacy in myeloma models. Furthermore, tofacitinib strongly synergized with venetoclax in coculture with bone marrow stromal cells but not in monoculture. Surprisingly, we found that ruxolitinib, an FDA approved agent targeting JAK1 and JAK2, did not lead to the same anti-myeloma effects. Combination with a novel irreversible JAK3-selective inhibitor also did not enhance ruxolitinib effects. Transcriptome analysis and unbiased phosphoproteomics revealed that bone marrow stromal cells stimulate a JAK/STAT-mediated proliferative program in myeloma cells, and tofacitinib reversed the large majority of these pro-growth signals. Taken together, our results suggest that tofacitinib reverses the growth-promoting effects of the tumor microenvironment. As tofacitinib is already FDA approved, these results can be rapidly translated into potential clinical benefits for myeloma patients.

IL-2Rβ abundance differentially tunes IL-2 signaling dynamics in CD4+ and CD8+ T cells

Interleukin-2 (IL-2) stimulates both activated CD4⁺ and CD8⁺ T cells to proliferate. IL-2 signals through an identical receptor complex and promotes the same dose-dependent phosphorylation of the canonical transcription factor STAT5 in both cell types. Despite this, CD8⁺ T cells enter the S phase earlier and proliferate to a greater extent than do CD4⁺ T cells in response to IL-2. We identified distinct IL-2 signaling dynamics in CD4⁺ and CD8⁺ T cells. In IL-2-stimulated CD8⁺ T cells, STAT5 phosphorylation increased rapidly and was sustained for 6 hours. In contrast, CD4⁺ T cells had a biphasic response, with maxima at 15 min and 2 to 4 hours after stimulation. Both cell types required vesicular trafficking, but only CD4⁺ T cells required new protein synthesis to maintain high phosphorylation of STAT5. Two subunits of the IL-2 receptor, IL-2Rβ and IL-2Rγ, were twice as abundant in CD8⁺ T cells than in CD4⁺ T cells. Reduction of IL-2Rβ abundance by 50% was sufficient to convert CD8⁺ T cells to a CD4⁺ T cell-like signaling pattern and delay S phase entry. These results suggest that the larger pool of IL-2Rβ chains in CD8⁺ T cells is required to sustain IL-2 signaling and contributes to the quantitatively greater proliferative response to IL-2 relative to that of CD4⁺ T cells. This cell type-specific difference in IL-2Rβ abundance appears to tune responses, potentially preventing extensive, autoimmune proliferation of CD4⁺ T cells, while still enabling sufficient proliferation of CD8⁺ T cells to control viral infections.

JAK/STAT pathway inhibition overcomes IL7-induced glucocorticoid resistance in a subset of human T-cell acute lymphoblastic leukemias

While outcomes for children with T-cell acute lymphoblastic leukemia (T-ALL) have improved dramatically, survival rates for patients with relapsed/refractory disease remain dismal. Prior studies indicate that glucocorticoid (GC) resistance is more common than resistance to other chemotherapies at relapse. In addition, failure to clear peripheral blasts during a prednisone prophase correlates with an elevated risk of relapse in newly diagnosed patients. Here we show that intrinsic GC resistance is present at diagnosis in early thymic precursor (ETP) T-ALLs as well as in a subset of non-ETP T-ALLs. GC-resistant non-ETP T-ALLs are characterized by strong induction of JAK/STAT signaling in response to interleukin-7 (IL7) stimulation. Removing IL7 or inhibiting JAK/STAT signaling sensitizes these T-ALLs, and a subset of ETP T-ALLs, to GCs. The combination of the GC dexamethasone and the JAK1/2 inhibitor ruxolitinib altered the balance between pro- and anti-apoptotic factors in samples with IL7-dependent GC resistance, but not in samples with IL7-independent GC resistance. Together, these data suggest that the addition of ruxolitinib or other inhibitors of IL7 receptor/JAK/STAT signaling may enhance the efficacy of GCs in a biologically defined subset of T-ALL.

Regulation of B cell fate by chronic activity of the IgE B cell receptor

IgE can trigger potent allergic responses, yet the mechanisms regulating IgE production are poorly understood. Here we reveal that IgE⁺ B cells are constrained by chronic activity of the IgE B cell receptor (BCR). In the absence of cognate antigen, the IgE BCR promoted terminal differentiation of B cells into plasma cells (PCs) under cell culture conditions mimicking T cell help. This antigen-independent PC differentiation involved multiple IgE domains and Syk, CD19, BLNK, Btk, and IRF4. Disruption of BCR signaling in mice led to consistently exaggerated IgE⁺ germinal center (GC) B cell but variably increased PC responses. We were unable to confirm reports that the IgE BCR directly promoted intrinsic apoptosis. Instead, IgE⁺ GC B cells exhibited poor antigen presentation and prolonged cell cycles, suggesting reduced competition for T cell help. We propose that chronic BCR activity and access to T cell help play critical roles in regulating IgE responses.

DOI:http://dx.doi.org/10.7554/eLife.21238.001

Antibodies are proteins that recognize and bind to specific molecules, and so help the immune system to defend the body against foreign substances that are potentially harmful. In some cases, harmless substances – such as pollen, dust or food – can trigger this response and lead to an allergic reaction. A type of antibody called immunoglobulin E (IgE) is particularly likely to trigger an allergic response.

In general, immune cells called plasma cells produce antibodies and release them into the body. However, in B cells – the cells from which plasma cells develop – the antibodies remain on the surface of the cells. Here, the antibody acts as a “receptor” that allows the B cell to tell when its antibody has bound to a specific substance.

Generally, B cells only activate when their B cell receptors bind to a specific substance. This binding triggers signals inside the cell that determine its fate – such as whether it will develop into a plasma cell. Recent studies have shown that B cells that have IgE on their surface (IgE⁺ B cells) are predisposed to develop rapidly into plasma cells.

To investigate why this is the case, Yang et al. have now studied B cells both in cell culture and in mice. The results show that the IgE B cell receptor autonomously signals to the cell even when it is not bound to a specific substance, in a manner that differs from other types of B cell receptors. This increases the likelihood that the IgE⁺ B cell will develop into a plasma cell and limits the competitive fitness of IgE⁺ B cells. These findings provide new insights into how IgE responses are regulated by the B cell receptor.

The next step will be to determine, at a molecular level, the basis for the autonomous signaling produced by the IgE B cell receptor when it is not bound to a specific substance. It will then be possible to investigate how this mechanism compares with the way that signals are normally transmitted when a B cell receptor binds to a specific substance.

DOI:http://dx.doi.org/10.7554/eLife.21238.002

Audit and review for evidence-based red cell wastage reduction measures

Stocks of red blood cells (RBC) are held to ideally match supply and demand; hold too great a stock and unnecessary wastage occurs; too low a stock results in delay or lack of blood for the patient. Blood is a precious resource and its supply needs to be managed effectively. The aim was to identify how RBC units are wasted and propose laboratory-based reduction measures that would not compromise the clinical requirements of the patient. Wastage of RBC was investigated using a 'dashboard' query of a laboratory information management system. By employing service improvement tools, proposals were made to reduce unnecessary RBC waste while ensuring an adequate supply to the patient. The efficacy of those proposals was examined using the same dashboard to compare similar periods before and after their introduction. The reduction in RBC wastage for all groups during an eight month period (December to July) was from 6.4% (5.3% non-AB or B RhD-positive) pre-implementation to 4.4% (2.5% non-AB/B RhD-positive) post-implementation. Group O RhD-negative wastage reduced from 10.4% to 4.4% after introduction of waste-saving proposals. However, there was an increase in staff time required to introduce the changes and in associated Group and Screen testing (3.4 to 3.8 per unit issued). RBC wastage was significantly reduced (P<0.0001) by 32.8% (52%, non-AB/B RhD-positive), saving approximately 225 RBC units per annum. Financially, increased associated costs did not negate the savings made by the measures introduced.

Essential biphasic role for JAK3 catalytic activity in IL-2 receptor signaling

To drive lymphocyte proliferation and differentiation, common γ-chain (γc) cytokine receptors require hours to days of sustained stimulation. JAK1 and JAK3 kinases are found together in all γc-receptor complexes, but how their respective catalytic activities contribute to signaling over time is not known. Here we dissect the temporal requirements for JAK3 kinase activity with a selective covalent inhibitor (JAK3i). By monitoring phosphorylation of the transcription factor STAT5 over 20 h in CD4(+) T cells stimulated with interleukin 2 (IL-2), we document a second wave of signaling that is much more sensitive to JAK3i than the first wave. Selective inhibition of this second wave is sufficient to block cyclin expression and entry to S phase. An inhibitor-resistant JAK3 mutant (C905S) rescued all effects of JAK3i in isolated T cells and in mice. Our chemical genetic toolkit elucidates a biphasic requirement for JAK3 kinase activity in IL-2-driven T cell proliferation and will find broad utility in studies of γc-receptor signaling.

Ternatin and improved synthetic variants kill cancer cells by targeting the elongation factor-1A ternary complex

Cyclic peptide natural products have evolved to exploit diverse protein targets, many of which control essential cellular processes. Inspired by a series of cyclic peptides with partially elucidated structures, we designed synthetic variants of ternatin, a cytotoxic and anti-adipogenic natural product whose molecular mode of action was unknown. The new ternatin variants are cytotoxic toward cancer cells, with up to 500-fold greater potency than ternatin itself. Using a ternatin photo-affinity probe, we identify the translation elongation factor-1A ternary complex (eEF1A·GTP·aminoacyl-tRNA) as a specific target and demonstrate competitive binding by the unrelated natural products, didemnin and cytotrienin. Mutations in domain III of eEF1A prevent ternatin binding and confer resistance to its cytotoxic effects, implicating the adjacent hydrophobic surface as a functional hot spot for eEF1A modulation. We conclude that the eukaryotic elongation factor-1A and its ternary complex with GTP and aminoacyl-tRNA are common targets for the evolution of cytotoxic natural products.

DOI:http://dx.doi.org/10.7554/eLife.10222.001

Many plants, fungi, and bacteria have evolved to produce small molecules that have powerful effects on the cells of other living organisms, and can even kill them. These naturally produced compounds are often used as starting points for developing new drugs. One such class of compounds are the cyclic peptides, which can be relatively easily produced in the laboratory and are able to penetrate cells. Some cyclic peptides have also proved to be useful for treating cancer and immune diseases, so researchers are keen to identify others that have similar effects. One promising prospect, called ternatin, is produced by several species of fungi. In high doses, ternatin can kill mammalian cells, but it was not clear how it does so.

To learn more, Carelli et al. searched a chemical database for cyclic peptides related to ternatin and identified several similar compounds that were reported to kill cancer cells. Inspired by the structures of these cyclic peptides, Carelli et al. synthesized modified versions of ternatin. One of these was 500 times more potent than ternatin, which means a much lower dose of the compound is still able to kill cancer cells.

Further experiments showed that ternatin blocks the production of new proteins in cells. Specifically, ternatin binds to a complex that includes a protein called elongation factor-1A (eEF1A). Mutations in a particular region of eEF1A prevent ternatin from killing cells, suggesting a potential binding site for ternatin.

The next challenge is to dissect the mechanism by which compounds binding to this site on eEF1A block protein synthesis and kill cells. A related challenge is to understand why certain cancer cells are hypersensitive to ternatin and other eEF1A inhibitors, while other cancer cells are relatively resistant. These questions are relevant to the development of eEF1A inhibitors as cancer treatments.

DOI:http://dx.doi.org/10.7554/eLife.10222.002

Fibroblast Biomarkers of Sporadic Parkinson's Disease and LRRK2 Kinase Inhibition

It has been uncertain whether specific disease-relevant biomarker phenotypes can be found using sporadic Parkinson’s disease (PD) patient-derived samples, as it has been proposed that there may be a plethora of underlying causes and pathological mechanisms. Fibroblasts derived from familial PD patients harboring leucine-rich repeat kinase 2 (LRRK2), PTEN-induced putative kinase 1 (PINK1), and Parkin mutations show clear disease-relevant mitochondrial phenotypes, which are exacerbated under conditions of pharmacological stress. We utilized fibroblasts derived from non-familial sporadic PD patients (without LRRK2 mutations) or LRRK2 mutation carriers to directly compare the cellular phenotypes during and after mitochondrial stress. We then determined the effects of pharmacological LRRK2 kinase inhibition using LRRK2-in-1. We found that there were two distinct populations of sporadic PD patient-derived fibroblast lines. One group of sporadic PD lines was highly susceptible to valinomycin-induced mitochondrial depolarization, emulating the mutant LRRK2 phenotype. These lines showed elevated mitochondrial superoxide/ nitric oxide levels, displayed increased mitochondrial and lysosome co-localization, and an increased rate of mitochondrial collapse, which corresponded with changes in mitochondrial fission and fusion proteins. The application of LRRK2-in-1 reversed decreased levels of mitochondrial and lysosome co-localization and partially restored mitochondrial network associated proteins and the mitochondrial membrane potential in the fibroblasts. This study identifies novel mitochondrial biomarkers in sporadic PD patient-derived fibroblast lines, which could be used as preclinical tools in which to test novel and known neuroprotective compounds.

Development and evaluation of a driving observation schedule (DOS) to study everyday driving performance of older drivers

This paper describes the development and evaluation of an on-road procedure, the Driving Observation Schedule (DOS), for monitoring individual driving behavior. DOS was developed for use in the Candrive/Ozcandrive five-year prospective study of older drivers. Key features included observations in drivers' own vehicles, in familiar environments chosen by the driver, with start/end points at their own homes. Participants were 33 drivers aged 75+ years, who drove their selected route with observations recorded during intersection negotiation, lane-changing, merging, low speed maneuvers and maneuver-free driving. Driving behaviors were scored by a specialist occupational therapy driving assessor and another trained observer. Drivers also completed a post-drive survey about the acceptability of DOS. Vehicle position, speed, distance and specific roadways traveled were recorded by an in-vehicle device installed in the participant's vehicle; this device was also used to monitor participants' driving over several months, allowing comparison of DOS trips with their everyday driving. Inter-rater reliability and DOS feasibility, acceptability and ecological validity are reported here. On average, drivers completed the DOS trip in 30.48min (SD=7.99). Inter-rater reliability measures indicated strong agreement between the trained and the expert observers: intra-class correlations (ICC)=0.905, CI 95% 0.747-0.965, p<0.0001; Pearson product correlation, r (18)=.83, p<0.05. Standard error of the measurement (SEM), method error (ME) and coefficient of variation (CV) measures were consistently small (3.0, 2.9 & 3.3%, respectively). Most participants reported being 'completely at ease' (82%) with the driving task and 'highly familiar with the route' (97%). Vehicle data showed that DOS trips were similar to participants' everyday driving trips in roads used, roadway speed limits, drivers' average speed and speed limit compliance. In summary, preliminary findings suggest that DOS can be scored reliably, is of feasible duration, is acceptable to drivers and representative of everyday driving. Pending further research with a larger sample and other observers, DOS holds promise as a means of quantifying and monitoring changes in older drivers' performance in environments typical of their everyday driving.

Increased efficacy of the 6-hydroxydopamine lesion of the median forebrain bundle in small rats, by modification of the stereotaxic coordinates

The 6-hydroxydopamine (6-OHDA) lesion is the most widely used rat model of Parkinson's disease. A single unilateral injection of 6-OHDA into the median forebrain bundle (MFB) selectively destroys dopamine neurons in the ipsilateral substantia nigra pars compacta (SNc) and ventral tegmental area (VTA), removing more than 95% of the dopamine innervation from target areas. The stereotaxic coordinates used to deliver 6-OHDA to the MFB have been used in our laboratory successfully for more than 25 years. However, in recent years we have observed a decline in the success rate of this lesion. Previously regular success rates of >80% of rats lesioned, have become progressively more variable, with rates as low as 20% recorded in some experiments. Having excluded variability of the neurotoxin and operator errors, we hypothesized that the change seen might be due to the use of smaller rats at the time of first surgery. An attempt to proportionally adjust the lesion coordinates base on head size did not increase lesion efficacy. However, in support of the small rat hypothesis it was observed that, using the standard coordinates, rat's heads had a "nose-up" position in the stereotaxic fame. Adjustment of the nose bar to obtain a flat head position during surgery improved lesion success, and subsequent adjustments of the lesion coordinates to account for smaller head size led to a greatly increased lesion efficacy (>90%) as assessed by amphetamine induced rotation.

Injury-related childhood mortality in migrant households in a southern city of China

BACKGROUND

Sporadic evidence from China suggests that migrant children are at higher risk of injury-related mortality than local indigenous children.

METHODS

Child deaths from 2004 to 2008 were provided by the Shenzhen Women and Child Health Surveillance System. Population data for children 1-4 years old were obtained from the Shenzhen Bureau of Statistics and number of live births was obtained from birth registration records. All-cause and injury-related childhood mortality rates and death causes were calculated and compared.

RESULTS

A total of 3774 deaths were identified. All-cause mortality rates per 10,000 dropped significantly from 66.28 (95% CI 60.50 to 72.06) in infants (<1 year old) and 7.40 (95% CI 6.16 to 8.64) in early childhood (1-4 years old) in 2004 to 40.42 (95% CI 37.31 to 43.53) and 3.97 (95% CI 3.36 to 4.58) in 2008. However, injury-related mortality rates did not change significantly from 2.36 (95% CI 1.27 to 3.45) in infants and 2.97 (95% CI 2.19 to 3.76) in early childhood in 2004 to 2.00 (95% CI 1.31 to 2.69) and 2.00 (95% CI 1.56 to 2.43) in 2008. Injury-related mortality rates were significantly higher among migrant children (p<0.05). Drowning and traffic crashes were the top two causes of early childhood injury deaths; suffocation was the leading cause of infant injury deaths.

CONCLUSION

Migrant children were at significantly higher risk of injury-related mortality than local indigenous children. Injury prevention in Shenzhen should target drowning and traffic safety among young children and suffocation among infants as top priorities.

Understanding graft-induced dyskinesia

The transplantation of dopaminergic cells for the treatment of symptoms of Parkinson&#x2019;s disease has several hurdles to overcome before it can be considered a successful therapeutic approach. One issue is the development of abnormal involuntary movements in the absence of L-3,4-dihydroxyphenylalanine following the transplantation of fetal ventral mesencephalon identified in three different clinical trials. Hypotheses as to the cause of these movements include: the composition of the graft, size of the graft, L-3,4-dihydroxyphenylalanine exposure and L-3,4-dihydroxyphenylalanine-induced dyskinesia prior to transplantation and inflammatory responses in and around the graft. We evaluate the clinical evidence supporting these hypotheses and the preclinical models upon which experiments are being based to resolve them.

Context-driven changes in L-DOPA-induced behaviours in the 6-OHDA lesioned rat

Both contralateral rotational behaviour and dyskinetic abnormal involuntary movements (AIMs) are induced by the administration of l-DOPA in the unilateral 6-OHDA lesioned rat model of Parkinson's disease. Since rotational responses can be conditioned to environmental cues we have investigated the extent to which drug-induced AIMS may also be conditioned by exteroceptive cues and experience. In Experiment I, 6-OHDA lesioned rats received repeated daily injections of l-DOPA either in their home cage (control) or in association with a brief (20 mins) exposure to the rotometers (paired). To assess conditioning, all animals then received two tests in the rotometer bowls. Following injection of saline the paired group both rotated more contralaterally and displayed manifest AIMs, neither of which were exhibited by the control rats. Moreover, following injection of l-DOPA, the paired group showed a trend for increased AIMs compared to controls. Two further studies provided longer exposure to the conditioning environments in counterbalanced designs. Although, using these parameters, re-exposure in the presence of saline did not induce context-dependent AIMs, a strong context-specific component of the sensitised response to l-DOPA was seen; chronic administration of drug produced a significantly stronger behavioural response in animals paired with a particular environment for drug administration than controls. This data suggests that part of the sensitisation of behavioural responding to l-DOPA administration is not solely a pharmacological phenomenon, but is also conditioned to the environmental context in which the drug is administered. This has clear implications for the clinical observation and experimental measurement of drug-induced dyskinesia in Parkinson's disease patients and animal models.

Effect of light on biomass and community structure of estuarine detrital microbiota

Comparison of estuarine detrital microbiota grown with and without light in the absence of macroscopic grazing showed shifts in the community structure that enabled correlation between various biochemical measures. Analysis of these biochemical measures showed that growth in light induces the smallest increases in procaryotic attributes such as muramic acid; wall glucosamine; lipid phosphate; total extractable adenosine nucleotides; short-branched, cyclopropane, and cis-vaccenic fatty acids; lipid glucose and mannose; the incorporation of acetate into lipid; and the formation of deoxyribonucleic acid from thymidine. Measures of the microfauna such as lipid inositol and the gamma-linolenic series of polyenoic fatty acids also increased minimally in the light-grown microbiota. Measures of sulfo-lipid synthesis, lipid glycerol, total extractable palmitate, 18-carbon polyenoic fatty acids, and total polyenoic fatty acids longer than 20 carbons increased 10- to 15-fold in algae and fungi. Chlorophyll a, lipid galactose, and the 16- and 20- carbon polyenoic fatty acids characteristic of diatoms increased maximally in the light. This increase of diatom measure correlated with the sheets of diatoms detected by scanning electron microscopy.

Unintentional pediatric submersion-injury-related hospitalizations in the United States, 2003

The objective of this study was to examine the demographic characteristics and hospital resource utilization of submersion-injury-related hospitalizations among persons < or =20 years of age in the USA in 2003. All 1475 pediatric submersion-injury-related hospital discharges in the Kids' Inpatient Database were identified by ICD-9-CM diagnosis code or external cause of injury code. These cases represent an estimated 2490 pediatric submersion-injury-related hospitalizations nationwide. Inpatient costs for these estimated hospitalizations were approximately $10 million. The overall pediatric submersion-injury-related rate of hospitalization was 3.0 per 100,000 persons. Children aged 0-4 years had the highest rate of hospitalization (7.7 per 100,000 persons). Children with permanent submersion-injury-related morbidity accounted for 5.8% of hospital admissions and 37.3% of hospital costs in our study, and children with submersion-injury-related in-hospital death accounted for 11.6% of hospital admissions and 20.0% of hospital costs in our study. Prevention of submersion injury using focused, proven strategies deserves increased attention.

The importance of using multiple techniques for detection of platelet antibodies

In red cell immunology, it has long been known that no one technique will detect all clinically significant antibodies. The same appears to be true for platelet immunology, and we highlight this fact by showing four examples of anti-human platelet antigen-1a that were not detected by the monoclonal antibody-specific immobilization of platelet antigen test, the most commonly used technique. Each antibody was found in a case of fetomaternal alloimmune thrombocytopenia in which the fetus or neonate was severely affected.

Wheelchair related injuries treated in US emergency departments

OBJECTIVE

To characterize the trend of wheelchair related injuries over time, and describe the demographics and characteristics of wheelchair users' injuries by age group.

METHODS

Data from the National Electronic Injury Surveillance System (NEISS) were analyzed.

RESULTS

In 2003, more than 100,000 wheelchair related injuries were treated in emergency departments in the US, double the number reported in 1991. Tips and falls accounted for 65-80% of injuries across all age groups of wheelchair users. The majority of children's injuries occurred at locations outside of homes and institutions/hospitals in environments with stairs, ramps, and curbs (57.3%). In contrast, injuries among adult users were more likely to occur in homes, hospitals, and institutions (45-90%).

CONCLUSIONS

Wheelchair related injuries may have increased in the US during the past decade. Prevention efforts should address the interacting complex factors that influence risk of injury while using a wheelchair.

Psychological symptoms and nonfatal unintentional injuries among Chinese adolescents: a prospective study

PURPOSE

To describe patterns of nonfatal unintentional injuries and investigate the association of psychological symptoms with injury risk among adolescents in Guangxi, China.

METHODS

Adolescents were selected from middle and high school students in Baise City, Guangxi, China. Psychological symptoms at baseline were measured using SCL-90-R and nonfatal unintentional injuries that occurred among participants were recorded using a standardized injury surveillance questionnaire. Annual injury rates per 100 adolescents by adolescents' demographic and family characteristics were calculated. Student's t-test and the Chi-square test were used to test differences in mean raw scores of SCL-90-R subscales and injury rates. Relative risks and odds ratios of injury with 95% confidence intervals were calculated in univariate analyses and multivariate logistic models.

RESULTS

A total of 1474 middle and high school students finished the study. Of them, 442 reported nonfatal unintentional injuries during the study period, resulting in an annual injury rate of 30.3 per 100 adolescents. Boys had a significantly higher injury rate than girls (32.6% vs. 27.4%). Injury rate decreased as the adolescents' age increased. Compared with adolescents who were not injured, the injured adolescents had higher average raw scores of all subscales of SCL-90-R, with an exception of the subscale for hostility. All SCL-90-R subscales factors, except those for hostility and phobia, were associated with injury risk. After confounding effects of age, gender, and ethnicity were controlled using logistic regression models, SCL-90-R subscales for somatization (OR = 2.00, 95% CI 1.52-2.63), obsessive-compulsiveness (OR = 2.10, 95% CI 1.71-2.58), interpersonal-sensitivity (OR = 1.66, 95% CI 1.34-2.06), depression (OR = 2.00, 95% CI 1.59-2.51), anxiety (OR = 2.08, 95% CI 1.62-2.66), and psychoticism (OR = 1.60, 95% CI 1.26-2.03) were significantly associated with an elevated injury risk.

CONCLUSION

Psychological symptoms are associated with an elevated risk of nonfatal unintentional injury among middle and high school students. Mental health services, such as psychological counseling, may help reduce the risk of nonfatal unintentional injuries among Chinese adolescents.

Comparison of velocity-log data collected using impeller and electromagnetic flowmeters

Previous studies have used flowmeters in environments that are within the expectations of their published ranges. Electromagnetic flowmeters have a published range from 0.1 to 79.0 m/min, and impeller flowmeters have a published range from 1.2 to 61.0 m/min. Velocity-log data collected in five long-screened production wells in the Pleasant Valley area of southern California showed that (1) electromagnetic flowmeter results were comparable within +/-2% to results obtained using an impeller flowmeter for comparable depths; (2) the measured velocities from the electromagnetic flowmeter were up to 36% greater than the published maximum range; and (3) both data sets, collected without the use of centralizers or flow diverters, produced comparable and interpretable results. Although either method is acceptable for measuring wellbore velocities and the distribution of flow, the electromagnetic flowmeter enables collection of data over a now greater range of flows. In addition, changes in fluid temperature and fluid resistivity, collected as part of the electromagnetic flowmeter log, are useful in the identification of flow and hydrogeologic interpretation.

Local modulation of plus-end transport targets herpesvirus entry and egress in sensory axons

The core structures of many viruses move within cells by association with host cytoskeletal motor proteins; however, the mechanisms by which intracellular viral particles are transported toward sites of replication or the cell periphery at distinct stages of infection remain to be understood. The regulation of herpesvirus directional transport in sensory neurons was examined by tracking individual viral capsids within axons at multiple frames per s. After entry into axons, capsids underwent bidirectional and saltatory movement to the cell body independently of endosomes. A comparison of entry transport to a previous analysis of capsid axonal transport during egress revealed that capsid targeting in and out of cells occurs by modulation of plus-end, but not minus-end, motion. Entry transport was unperturbed by the presence of egressing virus from a prior infection, indicating that transport direction is not modulated globally by viral gene expression, but rather directly by a component of the viral particle.

Downhill skiing injury fatalities among children

OBJECTIVE

Young skiers are at increased risk for injury, however, epidemiological data on skiing related fatal injuries among child skiers are scarce. This study aimed to provide information needed to develop injury control and prevention programs.

DESIGN AND SETTING

Study subjects came from Colorado, USA and were identified using a death certificate based surveillance system. Fatal injuries were limited to events that occurred at established commercial ski resorts in Colorado, and subjects were classified as child skiers (0-17 years) or adult skiers (> or =18 years).

MAIN OUTCOME MEASURE

Type and external cause, time, and week day of injury, gender and residency of the decedents.

RESULTS

During the study period from 1980-2001, 149 fatal injuries associated with downhill skiing were identified; 21 (14.1%) occurred among child skiers aged < or =17 years. The age of the youngest decedent was 7 years. In females the proportion of fatal injuries among child skiers was nearly three times that of adults. Traumatic brain injuries were the leading cause of death (67% of all deaths) among children, while multiple internal injuries and traumatic brain injuries accounted for almost equal proportions of fatal injuries among adults. Collision was the leading external mechanism of fatal injuries, accounting for more than two thirds of fatal injuries in both child and adult skiers.

CONCLUSIONS

Traumatic brain injury was the leading cause and collision was the leading external injury mechanism of fatal injuries associated with downhill skiing among child skiers. This underscores the importance of brain injury prevention strategies, including the use of ski helmets and prevention of collisions on ski slopes.

Predictors of a child's ability to use a visual analogue scale

BACKGROUND

Visual analogue scales (VAS) are used to assess the strength of perceptions of both children and adults in many clinical and research settings. Although the VAS has been shown by some authors to be reliable for use by children aged 5 years and older, others have proposed that young children, generally < or =7 years of age, may not have the conceptual ability to use a VAS.

OBJECTIVE

To identify demographic and cognitive variables that would maximize the accuracy of predicting children's abilities to use a VAS.

METHODS

Forty kindergarten children performed a seriation task, used a VAS to perform a calibration task and completed the Block Design and Vocabulary subtests of the Wechsler Preschool and Primary Scale of Intelligence-Revised (WPPSI-R). An estimated IQ was calculated from the WPPSI-R subtest scores. Socioeconomic status was assessed using the Hollingshead Four Factor Index of Social Status. Logistic regression was used to determine the best predictive models. Sensitivity, specificity, negative predictive value, positive predictive value and accuracy were calculated for statistically significant predictive models.

MAIN OUTCOME MEASURE

Successful completion of the calibration study by the child.

RESULTS

Only 42% of the subjects could use a VAS. The subject's age (> or =5.6 years), combined with estimated IQ (> or =100), was the best predictor of a child's ability to use a VAS (88% accuracy).

CONCLUSION

The majority of kindergarten children in our study could not complete a VAS accurately. Cognitive ability, combined with chronological age, was the best predictor of a child's accurate use of a VAS, as determined by logistic regression. Paediatric researchers may need to consider alternative rating scales to measure perceptions in children under 7 years of age.

A quick and simple method to obtain a radiographic evaluation of remaining alveolar bone height before implant placement

This article describes a method for making a diagnostic radiographic evaluation of remaining alveolar bone height in the bounded-saddle patient without the previous fabrication of a study model and radiographic ball-bearing template. The method presented is simple, enabling the busy practitioner to perform immediate radiographic diagnosis and inform the patient at the first visit about the available alveolar bone height at the site of planned implant insertion. This method is therefore time saving for both the dentist and the patient.

Directional spread of an alpha-herpesvirus in the nervous system

Pseudorabies virus (PRV), an alpha-herpesvirus, is capable of spreading between synaptically connected neurons in diverse hosts. In this report, two lines of experimentation are summarized that provide insight into the mechanism of virus spread in neurons. First, techniques were developed to measure the transport dynamics of capsids in infected neurons. Individual viral capsids labeled with green fluorescent protein (GFP) were visualized and tracked as they moved in axons away from infected neuronal cell bodies in culture during egress. Second, the effects of three viral membrane proteins (gE, gI and Us9) on the localization of envelope, tegument, and capsid proteins in infected, cultured sympathetic neurons were determined. These three proteins are necessary for spread of infection from pre-synaptic neurons to post-synaptic neurons in vivo (anterograde spread). Us9 mutants apparently are defective in anterograde spread in neural circuits because essential viral membrane proteins such as gB are not transported to axon terminals to facilitate spread to the connected neuron. By contrast, gE and gI mutants manifest their phenotype because these proteins most likely function at the axon terminal of the infected neuron to promote spread. These two sets of experiments are consistent with a model for herpesvirus spread in neurons first suggested by Cunningham and colleagues where capsids and envelope proteins, but not whole virions, are transported separately into the axon.

The appearance of a second genotype of Japanese encephalitis virus in the Australasian region

In mid-January 2000, the reappearance of Japanese encephalitis (JE) virus activity in the Australasian region was first demonstrated by the isolation of JE virus from 3 sentinel pigs on Badu Island in the Torres Strait. Further evidence of JE virus activity was revealed through the isolation of JE virus from Culex gelidus mosquitoes collected on Badu Island and the detection of specific JE virus neutralizing antibodies in 3 pigs from Saint Pauls community on Moa Island. Nucleotide sequencing and phylogenetic analyses of the premembrane and envelope genes were performed which showed that both the pig and mosquito JE virus isolates (TS00 and TS4152, respectively) clustered in genotype I, along with northern Thai, Cambodian, and Korean isolates. All previous Australasian JE virus isolates belong to genotype II, along with Malaysian and Indonesian isolates. Therefore, for the first time, the appearance and transmission of a second genotype of JE virus in the Australasian region has been demonstrated.

Genetic influence on the variance in P3 amplitude and latency

The P3(00) event-related potential (ERP) component is widely used as a measure of cognitive functioning and provides a sensitive electrophysiological index of the attentional and working memory demands of a task. This study investigated what proportion of the variance in the amplitude and latency of the P3, elicited in a delayed response working memory task, could be attributed to genetic factors. In 335 adolescent twin pairs and 48 siblings, the amplitude and latency of the P3 were examined at frontal, central, and parietal sites. Additive genetic factors accounted for 48% to 61% of the variance in P3 amplitude. Approximately one-third of the genetic variation at frontal sites was mediated by a common genetic factor that also influenced the genetic variation at parietal and central sites. Familial resemblance in P3 latency was due to genetic influence that accounted for 44% to 50% of the variance. Genetic covariance in P3 latency across sites was substantial, with a large part of the variance found at parietal, central, and frontal sites attributed to a common genetic factor. The findings provide further evidence that the P3 is a promising phenotype of neural activity of the brain and has the potential to be used in linkage and association analysis in the search for quantitative trait loci (QTLs) influencing cognition.

Genetic covariance among measures of information processing speed, working memory, and IQ

The genetic relationship between lower (information processing speed), intermediate (working memory), and higher levels (complex cognitive processes as indexed by IQ) of mental ability was studied in a classical twin design comprising 166 monozygotic and 190 dizygotic twin pairs. Processing speed was measured by a choice reaction time (RT) task (2-, 4-, and 8-choice), working memory by a visual-spatial delayed response task, and IQ by the Multidimensional Aptitude Battery. Multivariate analysis, adjusted for test-retest reliability, showed the presence of a genetic factor influencing all variables and a genetic factor influencing 4- and 8-choice RTs, working memory, and IQ. There were also genetic factors specific to 8-choice RT, working memory, and IQ. The results confirmed a strong relationship between choice RT and IQ (phenotypic correlations: -0.31 to -0.53 in females, -0.32 to -0.56 in males; genotypic correlations: -0.45 to -0.70) and a weaker but significant association between working memory and IQ (phenotypic: 0.26 in females, 0.13 in males; genotypic: 0.34). A significant part of the genetic variance (43%) in IQ was not related to either choice RT or delayed response performance, and may represent higher order cognitive processes.

Genetic influence on ERP slow wave measures of working memory

Individual differences in the variance of event-related potential (ERP) slow wave (SW) measures were examined. SW was recorded at prefrontal and parietal sites during memory and sensory trials of a delayed-response task in 391 adolescent twin pairs. Familial resemblance was identified and there was a strong suggestion of genetic influence. A common genetic factor influencing memory and sensory SW was identified at the prefrontal site (accounting for an estimated 35%-37% of the reliable variance) and at the parietal site (51%-52% of the reliable variance). Remaining reliable variance was influenced by unique environmental factors. Measurement error accounted for 24% to 30% of the total variance of each variable. The results show genetic independence for recording site, but not trial type, and suggest that the genetic factors identified relate more directly to brain structures, as defined by the cognitive functions they support, than to the cognitive networks that link them.

Development of a fluorogenic RT-PCR assay (TaqMan) for the detection of Hendra virus

A rapid and sensitive one-tube RT-PCR assay using a fluorogenic (TaqMan) probe was developed to improve the diagnosis of Hendra virus (HeV) infection. The TaqMan assay was developed to rapidly and specifically identify Hendra virus. The sensitivity of the new TaqMan-based PCR assay compared favourably with conventional RT-PCR. The major advantage of the TaqMan-based assay was the speed of diagnosis with results available within minutes of completing the PCR, and within 4 h of receiving the specimen. This test greatly reduces the chance of false positives through the elimination of second-round PCR and the requirement for agarose gel. Recombinant primer controls consisting of the Hendra virus primer sequence flanking a rodent GADPH probe sequence and recombinant probe controls consisting of the rodent GADPH primer sequence flanking the Hendra virus probe sequence were designed, cloned and transcribed in vitro to generate RNA. This has alleviated the requirement for viral RNA to be used as positive controls, thus reducing the chance of producing a false positive, at the same time eliminating the biosafety risk associated with handling live virus. This assay will provide a rapid diagnosis of future outbreaks of Hendra virus.

Potent anti-metastatic activity of combretastatin-A4

The requirement for tumour vascularisation to permit the expansion of solid tumours beyond a threshold size of approximately 1 mm diameter has focussed attention on anti-vascular and anti-angiogenic agents for cancer therapy. Combretastatin-A4 (cis CA-4P) is a tubulin-binding agent that is cytotoxic for proliferating endothelial cells in vitro and causes anti-vascular effects in the established tumour vessels of some primary tumours. Preliminary data from Phase I clinical trials indicate that cis CA-4 may also be effective in targeting the vasculature of human tumours. As metastatic disease is the principal cause of mortality in cancer, we have investigated the effects of cis CA-4 on metastatic development using an in vivo model. We show that bolus or continuous administration of cis CA-4P results in potent inhibition of metastases derived from ectopic primary Lewis lung carcinomas in mice whereas the trans CA-4 isomer is without effect. These data further characterise the activity of CA-4 in vivo and suggest that the drug should be evaluated clinically as an anti-metastatic agent.

Determination of the gram-positive bacterial content of soils and sediments by analysis of teichoic acid components

Many gram-positive bacteria form substituted polymers of glycerol and ribitol phosphate esters known as teichoic acids. Utilizing the relative specificity of cold concentrated hydrofluoric acid in the hydrolysis of polyphosphate esters it proved possible to quantitatively assay the teichoic acid-derived glycerol and ribitol from gram-positive bacteria added to various soils and sediments. The lipids are first removed from the soils or sediments with a one phase chloroform-methanol extraction and the lipid extracted residue is hydrolyzed with cold concentrated hydrofluoric acid. To achieve maximum recovery of the teichoic acid ribitol, a second acid hydrolysis of the aqueous extract is required. The glycerol and ribitol are then acetylated after neutralization and analyzed by capillary gas-liquid chromatography. This technique together with measures of the total phospholipid, the phospholipid fatty acid, the muramic acid and the hydroxy fatty acids of the lipopolysaccharide lipid A of the gram-negative bacteria makes it possible to describe the community structure environmental samples. The proportion of gram-positive bacteria measured as the teichoic acid glycerol and ribitol is higher in soils than in sediments and increases with depth in both.

Sensitivity of double contrast barium enema and colonoscopy for the detection of colorectal neoplasms

BACKGROUND

Double contrast barium enema (DCBE) is the examination carried out most frequently for investigation of patients with large bowel symptoms. The aim of this study was to compare the sensitivity of DCBE and colonoscopy for the detection of colorectal cancer and neoplastic polyps >/= 1 cm.

METHODS

All patients undergoing DCBE (1389) or colonoscopy (1081) as the primary investigation for large bowel symptoms or for cancer or polyp surveillance in the first 9 months of 1997 at a large teaching hospital were included in this study. At 1 and 2 years following investigation, a computerized search of appropriate diagnosis and procedure codes to detect any missed cancers or polyps was performed for all patients with a normal investigation.

RESULTS

Almost 19% of patients in both groups went on to have an additional large bowel investigation over the 2-year period. In the DCBE group, 47 patients (3.5%) had a cancer diagnosed; eight of them had been missed at the primary investigation (sensitivity 83%). In the colonoscopy group, 37 patients (3.4%) had a cancer; one of them had been missed at the primary investigation (sensitivity 97.5%). Neoplastic polyps >/= 1 cm were diagnosed in 1.6% of the DCBE group and in 7.7% of the colonoscopy group, with sensitivities of 21.7% and 91.4%, respectively. Nine patients (0.6%) had a false positive diagnosis of cancer in the DCBE group; one had an iatrogenic bowel perforation following flexible sigmoidoscopy.

CONCLUSIONS

Where adequate facilities and expertise exist, colonoscopy should be the investigation of choice for most patients with large bowel symptoms suggestive of neoplastic disease.

Sorting and transport of alpha herpesviruses in axons

The alpha herpesviruses, a subfamily of the herpesviruses, are neurotropic pathogens found associated with most mammalian species. The prototypic member of this subfamily is herpes simplex virus type 1, the causative agent of recurrent cold sores in humans. The mild nature of this disease is a testament to the complex and highly regulated life cycle of the alpha herpesviruses. The cellular mechanisms used by these viruses to disseminate infection in the nervous system are beginning to be understood. Here, we overview the life cycle of alpha herpesviruses with an emphasis on assembly and transport of viral particles in neurons.

Lawn mower-related injuries to children

Lawn mower-related injuries to children are relatively common and can result in severe injury or death. Many amputations during childhood are caused by power mowers. Pediatricians have an important role as advocates and educators to promote the prevention of these injuries.

Technical report: lawn mower-related injuries to children

In the United States, approximately 9400 children younger than 18 years receive emergency treatment annually for lawn mower-related injuries. More than 7% of these children require hospitalization, and power mowers cause a large proportion of the amputations during childhood. Prevention of lawn mower-related injuries can be achieved by design changes of lawn mowers, guidelines for mower operation, and education of parents, child caregivers, and children. Pediatricians have an important role as advocates and educators to promote the prevention of these injuries.

Effectiveness of a pediatric trauma team protocol

OBJECTIVE

To determine the effectiveness of a pediatric trauma triage system and resource allocation for emergency medicine and trauma services. TRAUMA SYSTEM: Two-tier trauma team activation system that triages patients into Level 1 and Level 2 trauma alert categories based on information provided by pre-hospital providers to pediatric emergency physicians at an American College of Surgeons' Level 1 pediatric trauma center in Columbus, Ohio.

METHODS

Using the hospital trauma registry database and patient medical records, a retrospective chart review was conducted on all (n = 542) admitted pediatric trauma patients from January 1995 through December 1996.

RESULTS

Level 1 patients had a higher median injury severity score and shorter emergency department (ED) length of stay time than Level 2 patients. Level 1 patients were more likely to be admitted to the pediatric intensive care unit and remain for more than 24 hours when compared to Level 2 patients. In addition, Level 1 patients were more likely to have procedures performed (eg, intubation, tube thoracostomy, thoracotomy, diagnostic peritoneal lavage) than Level 2 patients. The mortality rate was significantly higher for Level 1 patients and all ED deaths had been triaged to the Level 1 category.

CONCLUSIONS

This pediatric trauma triage system effectively predicts which patients will be more likely to have serious injury. By using a two-tier system, select patients may be managed by a smaller trauma team, thus improving staff utilization and possibly reducing costs while ensuring favorable outcomes.

The effect of Mg2+ on cardiac muscle function: Is CaATP the substrate for priming myofibril cross-bridge formation and Ca2+ reuptake by the sarcoplasmic reticulum?

Kinetics are established for the activation of the myofibril from the relaxed state [Smith, Dixon, Kirschenlohr, Grace, Metcalfe and Vandenberg (2000) Biochem. J. 346, 393-402]. These require two troponin Ca2+-binding sites, one for each myosin head, to act as a single unit in initial cross-bridge formation. This defines the first, or activating, ATPase reaction, as distinct from the further activity of the enzyme that continues when a cross-bridge to actin is already established. The pairing of myosin heads to act as one unit suggests a possible alternating mechanism for muscle action. A large positive inotropic (contraction-intensifying) effect of loading the Mg2+ chelator citrate, via its acetoxymethyl ester, into the heart has confirmed the competitive inhibition of the Ca2+ activation by Mg2+, previously seen in vitro. In the absence of a recognized second Ca2+ binding site on the myofibril, with appropriate binding properties, the bound ATP is proposed as the second activating Ca2+-binding site. As ATP, free or bound to protein, can bind either Mg2+ or Ca2+, this leads to competitive inhibition by Mg2+. Published physico-chemical studies on skeletal muscle have shown that CaATP is potentially a more effective substrate than MgATP for cross-bridge formation. The above considerations allow calculation of the observed variation of fractional activation by Ca2+ as a function of [Mg2+] and in turn reveal simple Michaelis-Menten kinetics for the activation of the ATPase by sub-millimolar [Mg2+]. Furthermore the ability of bound ATP to bind either cation, and the much better promotion of cross-bridge formation by CaATP binding, give rise to the observed variation of the Hill coefficient for Ca2+ activation with altered [Mg2+]. The inclusion of CaADP within the initiating cross-bridge and replacement by MgADP during the second cycle is consistent with the observed fall in the rate of the myofibril ATPase that occurs after two phosphates are released. The similarity of the kinetics of the cardiac sarcoplasmic reticulum ATPase to those of the myofibril, in particular the positive co-operativity of both Mg2+ inhibition and Ca2+ activation, leads to the conclusion that this ATPase also has an initiation step that utilizes CaATP. The first-order activation by sub-millimolar [Mg2+], similar to that of the myofibril, may be explained by Mg2+ involvement in the phosphate-release step of the ATPase. The inhibition of both the myofibril and sarcoplasmic reticulum Ca2+ transporting ATPases by Mg2+ offers an explanation for the specific requirement for phosphocreatine (PCr) for full activity of both enzymes in situ and its effect on their apparent affinities for ATP. This explanation is based on the slow diffusion of Mg2+ within the myofibril and on the contrast of PCr with both ATP and phosphoenolpyruvate, in that PCr does not bind Mg2+ under physiological conditions, whereas both the other two bind it more tightly than the products of their hydrolysis do. The switch to supply of energy by diffusion of MgATP into the myofibril when depletion of PCr raises [ATP]/[PCr] greatly, e.g. during anoxia, results in a local [Mg2+] increase, which inhibits the ATPase. It is possible that mechanisms similar to those described above occur in skeletal muscle but the Ca2+ co-operativity involved would be masked by the presence of two Ca2+ binding sites on each troponin.

Herpesviruses use bidirectional fast-axonal transport to spread in sensory neurons

Alpha herpesviruses infect the vertebrate nervous system resulting in either mild recurrent lesions in mucosal epithelia or fatal encephalitis. Movement of virions within the nervous system is a critical factor in the outcome of infection; however, the dynamics of individual virion transport have never been assessed. Here we visualized and tracked individual viral capsids as they moved in axons away from infected neuronal cell bodies in culture. The observed movement was compatible with fast axonal flow mediated by multiple microtubule motors. Capsids accumulated at axon terminals, suggesting that spread from infected neurons required cell contact.

Combretastatin-A4 disrupts neovascular development in non-neoplastic tissue

Combretastatin-A4 phosphate (cis-CA-4) is a tubulin-binding agent currently undergoing clinical trials as an anti-tumour drug. We have investigated whether CA-4 functions as a tumour-specific anti-vascular agent using the hyperplastic thyroid as a novel in vivo model of neovascularization. CA-4 elicited pathological changes in normal tissue, manifested as the induction of multiple, discrete intravascular thrombi. These vascular-damaging effects indicate that CA-4P does not function as a tumour-specific agent but targets neovasculature irrespective of the primary angiogenic stimulus.