Prehospital Early Warning Scores to Predict Mortality in Patients Using Ambulances

IMPORTANCE

Early warning scores (EWSs) are designed for in-hospital use but are widely used in the prehospital field, especially in select groups of patients potentially at high risk. To be useful for paramedics in daily prehospital clinical practice, evaluations are needed of the predictive value of EWSs based on first measured vital signs on scene in large cohorts covering unselected patients using ambulance services.

OBJECTIVE

To validate EWSs' ability to predict mortality and intensive care unit (ICU) stay in an unselected cohort of adult patients who used ambulances.

DESIGN, SETTING, AND PARTICIPANTS

This prognostic study conducted a validation based on a cohort of adult patients (aged ≥18 years) who used ambulances in the North Denmark Region from July 1, 2016, to December 31, 2020. EWSs (National Early Warning Score 2 [NEWS2], modified NEWS score without temperature [mNEWS], Quick Sepsis Related Organ Failure Assessment [qSOFA], Rapid Emergency Triage and Treatment System [RETTS], and Danish Emergency Process Triage [DEPT]) were calculated using first vital signs measured by ambulance personnel. Data were analyzed from September 2022 through May 2023.

MAIN OUTCOMES AND MEASURES

The primary outcome was 30-day-mortality. Secondary outcomes were 1-day-mortality and ICU admission. Discrimination was assessed using area under the receiver operating characteristic curve (AUROC) and area under the precision recall curve (AUPRC).

RESULTS

There were 107 569 unique patients (52 650 females [48.9%]; median [IQR] age, 65 [45-77] years) from the entire cohort of 219 323 patients who used ambulance services, among whom 119 992 patients (54.7%) had called the Danish national emergency number. NEWS2, mNEWS, RETTS, and DEPT performed similarly concerning 30-day mortality (AUROC range, 0.67 [95% CI, 0.66-0.68] for DEPT to 0.68 [95% CI, 0.68-0.69] for mNEWS), while qSOFA had lower performance (AUROC, 0.59 [95% CI, 0.59-0.60]; P vs other scores < .001). All EWSs had low AUPRCs, ranging from 0.09 (95% CI, 0.09-0.09) for qSOFA to 0.14 (95% CI, 0.13-0.14) for mNEWS.. Concerning 1-day mortality and ICU admission NEWS2, mNEWS, RETTS, and DEPT performed similarly, with AUROCs ranging from 0.72 (95% CI, 0.71-0.73) for RETTS to 0.75 (95% CI, 0.74-0.76) for DEPT in 1-day mortality and 0.66 (95% CI, 0.65-0.67) for RETTS to 0.68 (95% CI, 0.67-0.69) for mNEWS in ICU admission, and all EWSs had low AUPRCs. These ranged from 0.02 (95% CI, 0.02-0.03) for qSOFA to 0.04 (95% CI, 0.04-0.04) for DEPT in 1-day mortality and 0.03 (95% CI, 0.03-0.03) for qSOFA to 0.05 (95% CI, 0.04-0.05) for DEPT in ICU admission.

CONCLUSIONS AND RELEVANCE

This study found that EWSs in daily clinical use in emergency medical settings performed moderately in the prehospital field among unselected patients who used ambulances when assessed based on initial measurements of vital signs. These findings suggest the need of appropriate triage and early identification of patients at low and high risk with new and better EWSs also suitable for prehospital use.

Sickle cell bone disease and response to intravenous bisphosphonates in children

Children with sickle cell disease (SCD) have the potential for extensive and early-onset bone morbidity. This study reports on the diversity of bone morbidity seen in children with SCD followed at three tertiary centers. IV bisphosphonates were effective for bone pain analgesia and did not trigger sickle cell complications.

INTRODUCTION

To evaluate bone morbidity and the response to intravenous (IV) bisphosphonate therapy in children with SCD.

METHODS

We conducted a retrospective review of patient records from 2003 to 2019 at three Canadian pediatric tertiary care centers. Radiographs, magnetic resonance images, and computed tomography scans were reviewed for the presence of avascular necrosis (AVN), bone infarcts, and myositis. IV bisphosphonates were offered for bone pain management. Bone mineral density was assessed by dual-energy X-ray absorptiometry (DXA).

RESULTS

Forty-six children (20 girls, 43%) had bone morbidity at a mean age of 11.8 years (SD 3.9) including AVN of the femoral (17/46, 37%) and humeral (8/46, 17%) heads, H-shaped vertebral body deformities due to endplate infarcts (35/46, 76%), and non-vertebral body skeletal infarcts (15/46, 32%). Five children (5/26, 19%) had myositis overlying areas of AVN or bone infarcts visualized on magnetic resonance imaging. Twenty-three children (8/23 girls) received IV bisphosphonate therapy. They all reported significant or complete resolution of bone pain. There were no reports of sickle cell hemolytic crises, pain crises, or stroke attributed to IV bisphosphonate therapy.

CONCLUSION

Children with SCD have the potential for extensive and early-onset bone morbidity. In this series, IV bisphosphonates were effective for bone pain analgesia and did not trigger sickle cell complications.

Inter-domain horizontal gene transfer of nickel-binding superoxide dismutase

The ability of aerobic microorganisms to regulate internal and external concentrations of the reactive oxygen species (ROS) superoxide directly influences the health and viability of cells. Superoxide dismutases (SODs) are the primary regulatory enzymes that are used by microorganisms to degrade superoxide. SOD is not one, but three separate, non-homologous enzymes that perform the same function. Thus, the evolutionary history of genes encoding for different SOD enzymes is one of convergent evolution, which reflects environmental selection brought about by an oxygenated atmosphere, changes in metal availability, and opportunistic horizontal gene transfer (HGT). In this study, we examine the phylogenetic history of the protein sequence encoding for the nickel-binding metalloform of the SOD enzyme (SodN). The genomic potential to produce SodN is widespread among bacteria, including Actinobacteriota (Actinobacteria), Chloroflexota (Chloroflexi), Cyanobacteria, Proteobacteria, Patescibacteria, and others. The gene is also present in many archaea, with Thermoplasmatota and Nanoarchaeota representing the vast majority of archaeal sodN diversity. A comparison of organismal and SodN protein phylogenetic trees reveals several instances of HGT, including multiple inter-domain transfers of the sodN gene from the bacterial domain to the archaeal domain. Nearly half of the archaeal members with sodN live in the photic zone of the marine water column. The sodN gene is widespread and characterized by apparent vertical gene transfer in some sediment- or soil-associated lineages within the Actinobacteriota and Chloroflexota phyla, suggesting the ancestral sodN likely originated in one of these clades before expanding its taxonomic and biogeographic distribution to additional microbial groups in the surface ocean in response to decreasing iron availability. In addition to decreasing iron quotas, nickel-binding SOD has the added benefit of withstanding high reactant and product ROS concentrations without damaging the enzyme, making it particularly well suited for the modern surface ocean.

Risk of anticholinergic burden in adults with intellectual disabilities: a Scottish retrospective cohort study of n = 17 220

BACKGROUND

Several drugs have anticholinergic side effects that are associated with adverse health outcomes. Anticholinergic burden studies in adults with intellectual disabilities (ID) have focused exclusively on older adults. This study investigates anticholinergic burden and its associations in adults with ID of all ages (17-94 years).

METHODS

Adults with ID (n = 4 305), each with three general population age-sex-neighbourhood-matched controls (n = 12 915), were linked to their prescribed medications with anticholinergic effects between 2009 and 2017. Analyses were undertaken using logistic regression models.

RESULTS

Adults with ID were more likely to be prescribed any anticholinergic medicines, odds ratio (OR) = 1.49 (1.38-1.59), especially 'very strong' risk medicines, OR = 2.59 (2.39-2.81); 48.5% had very high total anticholinergic burden (3+) compared with 35.4% of the general population, OR = 1.77 (1.64-1.90). This group difference was greater for males, OR = 2.02 (1.84-2.22), than females, OR = 1.48 (1.33-1.65). Adults with ID had significantly higher odds of having very high total anticholinergic burden up to 75 years old, with the greatest group effect occurring in younger ages, 17-24-year-olds, OR = 3.05 (2.39-3.89), and the extent of the difference decreased as age increased. The main effect of neighbourhood deprivation showed greater group differences with increasing affluence of neighbourhood. Results examining only the ID group showed that very high total anticholinergic burden was greatest for females, OR = 1.21 (1.07-1.37), and those over age 55, and extent of neighbourhood deprivation was not significant.

CONCLUSIONS

Adults with ID are at higher risk of anticholinergic burden than the general population, especially young adults. Overall anticholinergic burden increased with age, but burden was high across all ages in the ID group. Very high total anticholinergic burden is prevalent across all types of neighbourhoods for the adults with ID, in contrast to the steeper gradient seen in the general population. Adults with ID have increased likelihood of unintended adverse effects, regardless of potential confounds, so clinicians undertaking medication reviews need to consider anticholinergic side effects and cumulative burden across concomitant medications, including in young adults with ID, not just older adults, and particularly women.

Phanerozoic radiation of ammonia oxidizing bacteria

The modern nitrogen cycle consists of a web of microbially mediated redox transformations. Among the most crucial reactions in this cycle is the oxidation of ammonia to nitrite, an obligately aerobic process performed by a limited number of lineages of bacteria (AOB) and archaea (AOA). As this process has an absolute requirement for O2, the timing of its evolution-especially as it relates to the Great Oxygenation Event ~ 2.3 billion years ago-remains contested and is pivotal to our understanding of nutrient cycles. To estimate the antiquity of bacterial ammonia oxidation, we performed phylogenetic and molecular clock analyses of AOB. Surprisingly, bacterial ammonia oxidation appears quite young, with crown group clades having originated during Neoproterozoic time (or later) with major radiations occurring during Paleozoic time. These results place the evolution of AOB broadly coincident with the pervasive oxygenation of the deep ocean. The late evolution AOB challenges earlier interpretations of the ancient nitrogen isotope record, predicts a more substantial role for AOA during Precambrian time, and may have implications for understanding of the size and structure of the biogeochemical nitrogen cycle through geologic time.

Dental attendance, restoration and extractions in adults with intellectual disabilities compared with the general population: a record linkage study

BACKGROUND

Oral health may be poorer in adults with intellectual disabilities (IDs) who rely on carer support and medications with increased dental risks.

METHODS

Record linkage study of dental outcomes, and associations with anticholinergic (e.g. antipsychotics) and sugar-containing liquid medication, in adults with IDs compared with age-sex-neighbourhood deprivation-matched general population controls.

RESULTS

A total of 2933/4305 (68.1%) with IDs and 7761/12 915 (60.1%) without IDs attended dental care: odds ratio (OR) = 1.42 [1.32, 1.53]; 1359 (31.6%) with IDs versus 5233 (40.5%) without IDs had restorations: OR = 0.68 [0.63, 0.73]; and 567 (13.2%) with IDs versus 2048 (15.9%) without IDs had dental extractions: OR = 0.80 [0.73, 0.89]. Group differences for attendance were greatest in younger ages, and restoration/extractions differences were greatest in older ages. Adults with IDs were more likely prescribed with anticholinergics (2493 (57.9%) vs. 6235 (48.3%): OR = 1.49 [1.39, 1.59]) and sugar-containing liquids (1641 (38.1%) vs. 2315 (17.9%): OR = 2.89 [2.67, 3.12]).

CONCLUSION

Carers support dental appointments, but dentists may be less likely to restore teeth, possibly extracting multiple teeth at individual appointments instead.

Oral health of adults with intellectual disabilities: a systematic review

BACKGROUND

There have been several past reports that adults with intellectual disabilities experience poor oral health (tooth loss, periodontal health and untreated dental caries). Loss of a functional dentition has serious consequences, including problems with chewing, swallowing, nutrition, speech, temporomandibular joint osteoarthritis and pain and systemic health conditions. Poor oral health is largely preventable through proactive oral care support. In recent years, social care provision for adults has changed, with deinstitutionalisation and home-based personalised care now being the typical provision in high income countries. Hence, oral health inequalities might be reducing. However, there is limited recent evidence-synthesis on the topic. We aimed to address this.

METHOD

PROSPERO registration number: CRD42018089880. We conducted a preferred reporting items for systematic reviews and meta-analyses systematic review of publications since 2008. Four databases were searched with a clear search strategy, strict inclusion criteria for selection of papers, double scoring (two raters), systematic data extraction and quality appraisal of included papers.

RESULTS

A total of 33/3958 retrieved articles were included, of which 14 were drawn from dental service users and 10 from Special Olympic athletes, therefore not necessarily being representative of the wider population with intellectual disabilities. Despite this limitation, adults with intellectual disabilities were still shown to experience poor oral health. High levels of poor oral hygiene and gingivitis were found, with many also affected by periodontitis and untreated dental decay. There is clear unmet need relating to both periodontal (gum) and tooth health, leading to tooth loss.

CONCLUSIONS

Despite reports in the past of poor oral health amongst adults with intellectual disabilities, and despite it being preventable, there remains a high burden of poor oral health. This highlights the need to raise awareness, and for polices on effective daily oral care, and appropriate service provision. The importance of oral health and its possible negative sequelae needs to be elevated amongst carers and professionals.

Rapidly forming, slowly evolving, spatial patterns from quasi-cycle Mexican Hat coupling

Alattice-indexed familyof stochasticprocesses hasquasi-cycle oscillationsif itsotherwise-damped oscillations are sustained by noise. Such a family performs the reaction part of a discrete stochastic reaction-diffusion system when we insert a local Mexican Hat-type, difference of Gaussians, coupling on a one-dimensional and on a two-dimensional lattice. Quasi-cycles are a proposed mech-anism for the production of neural oscillations, and Mexican Hat coupling is ubiquitous in the brain. Thus this combination might provide insight into the function of neural oscillations in the brain. Im-portantly, we study this system only in the transient case, on time intervals before saturation occurs. In one dimension, for weak coupling, we find that the phases of the coupled quasi-cycles synchronize (es-tablish a relatively constant relationship, or phase lock) rapidly at coupling strengths lower than those required to produce spatial patterns of their amplitudes. In two dimensions the amplitude patterns form more quickly, but there remain parameter regimes in which phase synchronization patterns form with-out being accompanied by clear amplitude patterns. At higher coupling strengths we find patterns both of phase synchronization and of amplitude (resembling Turing patterns) corresponding to the patterns of phase synchronization. Specific properties of these patterns are controlled by the parameters of the reaction and of the Mexican Hat coupling.

Automated DXA-based finite element analysis for hip fracture risk stratification: a cross-sectional study

Fracture risk indices (FRIs) generated from DXA-based finite element analysis were associated with hip fracture independent of FRAX score computed with femoral neck bone mineral density (BMD). Prospective studies are warranted to determine whether FRIs represent an improvement over BMD for predicting incident hip fractures.

INTRODUCTION

The study aims to examine the association between prior hip fracture and FRIs derived from automated finite element analysis (FEA) of DXA hip scans. Femoral neck, intertrochanteric, and subtrochanteric FRIs were calculated as the von Mises stress induced by a sideways fall divided by the bone yield stress over the specified region of interest (ROI).

METHODS

Using the Manitoba Bone Mineral Density Database, we selected women age ≥ 65 years with femoral neck T-scores below - 1 and no osteoporosis treatment. From this population, we identified 324 older women with hip fracture before DXA testing and a random sample of 658 non-fracture controls. FRIs were derived from the anonymized DXA scans. Logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs) for the associations between FRIs (per SD increase) and hip fracture.

RESULTS

After adjusting for FRAX score (hip fracture with BMD), femoral neck FRI (OR 1.36, 95% CI 1.13, 1.64), intertrochanteric FRI (OR 1.81, 95% CI 1.44, 2.27), and subtrochanteric FRI (OR 2.09, 95% CI 1.68, 2.60) were associated with hip fracture. Intertrochanteric and subtrochanteric FRIs gave significantly higher c-statistics (all P ≤ 0.05) than femoral neck BMD. Subgroup analyses showed that all FRIs were more strongly associated with hip fracture in women who were younger and had higher body mass index (BMI) or non-osteoporotic BMD (all P _interaction < 0.1).

CONCLUSIONS

FRIs derived from DXA-based FEA were independently associated with prior hip fracture, suggesting that they could potentially improve hip fracture risk assessment.

Microbial diversity and iron oxidation at Okuoku-hachikurou Onsen, a Japanese hot spring analog of Precambrian iron formations

Banded iron formations (BIFs) are rock deposits common in the Archean and Paleoproterozoic (and regionally Neoproterozoic) sedimentary successions. Multiple hypotheses for their deposition exist, principally invoking the precipitation of iron via the metabolic activities of oxygenic, photoferrotrophic, and/or aerobic iron-oxidizing bacteria. Some isolated environments support chemistry and mineralogy analogous to processes involved in BIF deposition, and their study can aid in untangling the factors that lead to iron precipitation. One such process analog system occurs at Okuoku-hachikurou (OHK) Onsen in Akita Prefecture, Japan. OHK is an iron- and CO₂ -rich, circumneutral hot spring that produces a range of precipitated mineral textures containing fine laminae of aragonite and iron oxides that resemble BIF fabrics. Here, we have performed 16S rRNA gene amplicon sequencing of microbial communities across the range of microenvironments in OHK to describe the microbial diversity present and to gain insight into the cycling of iron, oxygen, and carbon in this ecosystem. These analyses suggest that productivity at OHK is based on aerobic iron-oxidizing Gallionellaceae. In contrast to other BIF analog sites, Cyanobacteria, anoxygenic phototrophs, and iron-reducing micro-organisms are present at only low abundances. These observations support a hypothesis where low growth yields and the high stoichiometry of iron oxidized per carbon fixed by aerobic iron-oxidizing chemoautotrophs like Gallionellaceae result in accumulation of iron oxide phases without stoichiometric buildup of organic matter. This system supports little dissimilatory iron reduction, further setting OHK apart from other process analog sites where iron oxidation is primarily driven by phototrophic organisms. This positions OHK as a study area where the controls on primary productivity in iron-rich environments can be further elucidated. When compared with geological data, the metabolisms and mineralogy at OHK are most similar to specific BIF occurrences deposited after the Great Oxygenation Event, and generally discordant with those that accumulated before it.

Musculoskeletal health in newly diagnosed children with Crohn's disease

We evaluated the impact of Crohn's disease on muscle and bone strength, mass, density, and geometry in children with newly diagnosed CD and found profound muscle and bone deficits; nevertheless, the prevalence of vertebral fractures at this time point was low.

INTRODUCTION

Crohn's disease (CD) is an inflammatory condition of the gastrointestinal tract that can affect the musculoskeletal system. The objective of this study was to determine the prevalence of vertebral fractures and the impact of CD on muscle and bone mass, strength, density, and geometry in children with newly diagnosed CD.

METHODS

Seventy-three children (26 girls) aged 7.0 to 17.7 years were examined within 35 days following CD diagnosis by lateral spine radiograph for vertebral fractures and by jumping mechanography for muscle strength. Bone and muscle mass, density, and geometry were assessed by dual-energy x-ray absorptiometry and peripheral quantitative computed tomography (pQCT).

RESULTS

Disease activity was moderate to severe in 66 (90%) patients. Mean height (Z-score -0.3, standard deviation (SD) 1.1, p = 0.02), weight (Z-score -0.8, SD 1.3, p < 0.01), body mass index (Z-score -1.0, SD 1.3, p < 0.01), lumbar spine areal bone mineral density (BMD; Z-score -1.1, SD 1.0, p < 0.01), total body bone mineral content (Z-score -1.5, SD 1.0, p < 0.01), and total body lean mass (Z-score -2.5, SD 1.1, p < 0.01) were all low for age and gender. pQCT showed reduced trabecular volumetric BMD at the tibial metaphysis, expansion of the bone marrow cavity and thin cortices at the diaphysis, and low calf muscle cross-sectional area. Jumping mechanography demonstrated low muscle power. Only one patient had a vertebral fracture.

CONCLUSIONS

Children with newly diagnosed CD have profound muscle and bone deficits; nevertheless, the prevalence of vertebral fractures at this time point was low.

Molecular diagnosis in children with fractures but no extraskeletal signs of osteogenesis imperfecta

In 26 of 94 individuals (28%) below 21 years of age who had a significant fracture history but did not have extraskeletal features of osteogenesis imperfecta (OI), we detected disease-causing mutations in OI-associated genes.

INTRODUCTION

In children who have mild bone fragility but do not have extraskeletal features of OI, it can be difficult to establish a diagnosis on clinical grounds. Here, we assessed the diagnostic yield of genetic testing in this context, by sequencing a panel of genes that are associated with OI.

METHODS

DNA sequence analysis was performed on 94 individuals below 21 years of age who had a significant fracture history but had white sclera and no signs of dentinogenesis imperfecta.

RESULTS

Disease-causing variants were detected in 28% of individuals and affected 5 different genes. Twelve individuals had mutations in COL1A1 or COL1A2, 8 in LRP5, 4 in BMP1, and 2 in PLS3.

CONCLUSIONS

DNA sequence analysis of currently known OI-associated genes identified disease-causing variants in more than a quarter of individuals with a significant fracture history but without extraskeletal manifestations of OI.

Unified principles of thalamo-cortical processing: the neural switch

It has been reported that cross-frequency interactions may play an important role in local processing within thalamus and neocortex, as well as information transfer between subcortical and cortico-cortical brain regions. Strong commonalities in rhythmic network properties have been observed across recording techniques and task demands, but strong neuroscientific theories to situate such observations within a unified framework with direct relevance to explain neuropathologies remain scarce. Based on a comprehensive review of animal and human literature, we probe and introduce a neurophysiological framework to explain how coordinated cross-frequency and interregional oscillatory cortical dynamics underlie typical and atypical brain activation, and the formation of distributed functional ensembles supporting cortical networks underpinning perception and cognition. We propose that local regional activation by an external stimulus via a sensory pathway entails (1) attenuated alpha (8-14 Hz) and increased theta (4-8 Hz) and gamma (30-50 Hz) oscillatory activity, and (2) increased interactions among theta and gamma rhythms. These local dynamics also mediate the integration of activated neural populations into large-scale functional assemblies through neuronal synchronization. This comprehensive perspective into the animal and human literature indicates a further thinking beyond synchrony and connectivity and the readiness for more hypothesis-driven research and modeling toward unified principles of thalamo-cortical processing. We further introduced such a possible framework: "The ATG switch". We also discussed evidence that alpha-theta-gamma dynamics emerging from thalamocortical interactions may be implicated and disrupted in numerous neurological and neuropsychiatric conditions.

The time to and determinants of first fractures in boys with Duchenne muscular dystrophy

Boys with vertebral fractures (VF) identified through routine spine radiographs had milder, less symptomatic, and fewer VF compared to those diagnosed with VF following consultation for back pain. Spontaneous (i.e., medication-unassisted) reshaping of fractured vertebral bodies was absent. Long bone fractures were present even before Duchenne muscular dystrophy (DMD) diagnosis in some boys.

INTRODUCTION

The objective of the study was to determine the time to and characteristics of first fractures in Duchenne muscular dystrophy.

METHODS

This study was a retrospective longitudinal study of 30 boys with DMD <18 years. Boys were classified into four groups according to their first fracture: those with VF identified on routine lateral spine radiographs, those with VF diagnosed following consultation for back pain, those with long bone fractures, and those without fractures.

RESULTS

Compared to boys diagnosed with VF as their initial fracture following consultation for back pain, those with VF surveillance radiographs had shorter durations of glucocorticoid (GC) therapy at the time of VF diagnosis (median 1.6 versus 5.3 years, p < 0.01), higher areal (mean ± standard deviation -1.4 ± 0.7 versus -3.1 ± 0.8, p = 0.01), and volumetric (-0.3 ± 0.5 versus -2.6 ± 0.8, p < 0.01) lumbar spine bone mineral density Z-scores, as well as fewer VF (median 1.4 versus 5.2 per person, p < 0.01) and a lower median spinal deformity index (median 1.5 versus 9.5, p < 0.01). Vertebral body reshaping following VF was not observed. Ten boys sustained a long bone fracture as their first fracture at a mean age of 8.9 ± 4.0 years; four of these boys later sustained a total of 27 incident VF.

CONCLUSIONS

Routine lateral spine radiographs led to detection of VF in their earlier stages, vertebral body reshaping following VF was absent, and VF were frequent after the first long bone fracture. These results support the inclusion of a lateral spine radiograph starting at the time of GC initiation as part of routine bone health monitoring in DMD.

Crown group Oxyphotobacteria postdate the rise of oxygen

The rise of oxygen ca. 2.3 billion years ago (Ga) is the most distinct environmental transition in Earth history. This event was enabled by the evolution of oxygenic photosynthesis in the ancestors of Cyanobacteria. However, long-standing questions concern the evolutionary timing of this metabolism, with conflicting answers spanning more than one billion years. Recently, knowledge of the Cyanobacteria phylum has expanded with the discovery of non-photosynthetic members, including a closely related sister group termed Melainabacteria, with the known oxygenic phototrophs restricted to a clade recently designated Oxyphotobacteria. By integrating genomic data from the Melainabacteria, cross-calibrated Bayesian relaxed molecular clock analyses show that crown group Oxyphotobacteria evolved ca. 2.0 billion years ago (Ga), well after the rise of atmospheric dioxygen. We further estimate the divergence between Oxyphotobacteria and Melainabacteria ca. 2.5-2.6 Ga, which-if oxygenic photosynthesis is an evolutionary synapomorphy of the Oxyphotobacteria-marks an upper limit for the origin of oxygenic photosynthesis. Together, these results are consistent with the hypothesis that oxygenic photosynthesis evolved relatively close in time to the rise of oxygen.

The management of osteoporosis in children

This article reviews the manifestations and risk factors associated with osteoporosis in childhood, the definition of osteoporosis and recommendations for monitoring and prevention. As well, this article discusses when a child should be considered a candidate for osteoporosis therapy, which agents should be prescribed, duration of therapy and side effects. There has been significant progress in our understanding of risk factors and the natural history of osteoporosis in children over the past number of years. This knowledge has fostered the development of logical approaches to the diagnosis, monitoring, and optimal timing of osteoporosis intervention in this setting. Current management strategies are predicated upon monitoring at-risk children to identify and then treat earlier rather than later signs of osteoporosis in those with limited potential for spontaneous recovery. On the other hand, trials addressing the prevention of the first-ever fracture are still needed for children who have both a high likelihood of developing fractures and less potential for recovery. This review focuses on the evidence that shapes the current approach to diagnosis, monitoring, and treatment of osteoporosis in childhood, with emphasis on the key pediatric-specific biological principles that are pivotal to the overall approach and on the main questions with which clinicians struggle on a daily basis. The scope of this article is to review the manifestations of and risk factors for primary and secondary osteoporosis in children, to discuss the definition of pediatric osteoporosis, and to summarize recommendations for monitoring and prevention of bone fragility. As well, this article reviews when a child is a candidate for osteoporosis therapy, which agents and doses should be prescribed, the duration of therapy, how the response to therapy is adjudicated, and the short- and long-term side effects. With this information, the bone health clinician will be poised to diagnose osteoporosis in children and to identify when children need osteoporosis therapy and the clinical outcomes that gauge efficacy and safety of treatment.

Skeletal findings in the first 12 months following initiation of glucocorticoid therapy for pediatric nephrotic syndrome

Incident vertebral fractures and lumbar spine bone mineral density (BMD) were assessed in the 12 months following glucocorticoid initiation in 65 children with nephrotic syndrome. The incidence of vertebral fractures was low at 12 months (6 %) and most patients demonstrated recovery in BMD Z-scores by this time point.

INTRODUCTION

Vertebral fracture (VF) incidence following glucocorticoid (GC) initiation has not been previously reported in pediatric nephrotic syndrome.

METHODS

VF was assessed on radiographs (Genant method); lumbar spine bone mineral density (LS BMD) was evaluated by dual-energy X-ray absorptiometry.

RESULTS

Sixty-five children were followed to 12 months post-GC initiation (median age, 5.4 years; range, 2.3-17.9). Three of 54 children with radiographs (6 %; 95 % confidence interval (CI), 2-15 %) had incident VF at 1 year. The mean LS BMD Z-score was below the healthy average at baseline (mean ± standard deviation (SD), -0.5 ± 1.1; p = 0.001) and at 3 months (-0.6 ± 1.1; p < 0.001), but not at 6 months (-0.3 ± 1.3; p = 0.066) or 12 months (-0.3 ± 1.2; p = 0.066). Mixed effect modeling showed a significant increase in LS BMD Z-scores between 3 and 12 months (0.22 SD; 95 % CI, 0.08 to 0.36; p = 0.003). A subgroup (N = 16; 25 %) had LS BMD Z-scores that were ≤-1.0 at 12 months. In these children, each additional 1,000 mg/m(2) of GC received in the first 3 months was associated with a decrease in LS BMD Z-score by 0.39 at 12 months (95 % CI, -0.71 to -0.07; p = 0.017).

CONCLUSIONS

The incidence of VF at 1 year was low and LS BMD Z-scores improved by 12 months in the majority. Twenty-five percent of children had LS BMD Z-scores ≤-1.0 at 12 months. In these children, LS BMD Z-scores were inversely associated with early GC exposure, despite similar GC exposure compared to the rest of the cohort.

The development of bone mineral lateralization in the arms

Bone mineral content (BMC) is known to be greater in the dominant arm after the age of 8 years. We studied a group of children and found that BMC sidedness gradually increased up to the age of 6 years and then remained stable into late adolescence.

INTRODUCTION

Bone mineral content (BMC) exhibits sidedness in the arms after the age of 8 years, but it is not known whether BMC is greater in the dominant arm from birth or whether lateralization develops in early childhood. To address this, we examined bone mineral status in relation to handedness and age.

METHODS

Subjects (N = 158) were children recently initiating glucocorticoids for underlying disease (leukemia 43 %, rheumatic conditions 39 %, nephrotic syndrome 18 %). Handedness was determined by questionnaire and BMC by dual-energy X-ray absorptiometry.

RESULTS

Median age was 7.2 years (range, 1.5 to 17.0 years), 49 % was male, and the spine BMD Z-score was -0.9 (SD, 1.3). By linear regression, BMC sidedness in the arms was significantly related to age (r = 0.294, p = 0.0005). Breakpoint analysis revealed two lines with a knot at 6.0 years (95 % CI, 4.5-7.5 years). The formula for the first line was: dominant:nondominant arm BMC ratio = 0.029 × age [in years] + 0.850 (r = 0.323, p = 0.017). The slope of the second line was not different from 0 (p = 0.332), while the slopes for the two lines were significantly different (p = 0.027).

CONCLUSIONS

These results show that arm BMC sidedness in this patient group develops up to age 6 years and then remains stable into late adolescence. This temporal profile is consistent with mechanical stimulation of the skeleton in response to asymmetrical muscle use as handedness becomes manifest.

The use of intravenous bisphosphonate therapy to treat vertebral fractures due to osteoporosis among boys with Duchenne muscular dystrophy

The impact of intravenous bisphosphonate treatment to treat painful vertebral fractures in boys with DMD has not been documented. In this retrospective observational study of seven boys, 2 years of intravenous bisphosphonate therapy was associated with back pain improvement and stabilization or increases in the height ratios of fractured vertebrae.

INTRODUCTION

Boys with Duchenne muscular dystrophy (DMD) are at risk for vertebral fractures. We studied the impact of intravenous bisphosphonate therapy for the treatment of painful vertebral fractures in DMD.

METHODS

This was a retrospective observational study in seven boys with DMD (median 11.6 years, range 8.5 to 14.3) treated with intravenous pamidronate (9 mg/kg/year) or zoledronic acid (0.1 mg/kg/year) for painful vertebral fractures.

RESULTS

At baseline, 27 vertebral fractures were evident in the seven boys. After 2 years of bisphosphonate therapy, 17 of the fractures had an increase in the most severely affected vertebral height ratio, 10 vertebrae stabilized, and none showed a decrease in height ratio. Back pain resolved completely (N = 3) or improved (N = 4). The median change in lumbar spine volumetric bone mineral density Z-score was 0.5 standard deviations (interquartile range, -0.3 to 1.7). Two boys had three incident vertebral fractures in previously normal vertebral bodies that developed over the observation period. There was a decline in the trabecular bone formation rate on trans-iliac bone biopsy but no evidence of osteomalacia. First-dose side effects included fever and malaise (N = 4), hypocalcemia (N = 2), and vomiting (N = 1); there were no side effects with subsequent infusions.

CONCLUSIONS

Intravenous bisphosphonate therapy was associated with improvements in back pain and stabilization to improvement in vertebral height ratios of previously fractured vertebral bodies. At the same time, such therapy does not appear to completely prevent the development of new vertebral fractures in this context.

Anatomical distribution of vertebral fractures: comparison of pediatric and adult spines

SUMMARY

We compared the distribution of vertebral fractures in adults and children and found that fractures occurred in different locations in the two age groups. This likely relates to the different shape of the immature spine.

INTRODUCTION

We hypothesized that the anatomical distribution of vertebral fractures (VF) would be different in children compared to adults.

METHODS

We compared the distribution of VF defined using the Genant semi-quantitative method (GSQ method) in adults (N = 221; 545 fractures) and in children early in the course of glucocorticoid therapy (N = 44; 94 fractures).

RESULTS

The average age in the adult cohort was 62.9 years (standard deviation (SD), 13.4 years), 26% was male, the mean lumbar spine Z-score was -1.0 (SD, 1.5), and the corresponding T-score was -2.4 (SD, 1.4). The pediatric cohort median age was 7.7 years (range, 2.1-16.6 years), the mean lumbar spine Z-score was -1.7 (SD, 1.5), 52% was male, and disease categories were acute lymphoblastic leukemia (66%), rheumatological conditions (21%), and nephrotic syndrome (14%). The VF distribution was biphasic in both populations, but the peaks differed in location. In adults, the peaks were at T7/T8 and at T12/L1. In children, the focus was higher in the thoracic spine, at T6/T7, and lower in the lumbar spine, at L1/L2. When children were assessed in two age-defined sub-groups, a biphasic VF distribution was seen in both, but the upward shift of the thoracic focus to T6 was observed only in the older group, with the highest rates of fracture present between ages 7 and 10 years.

CONCLUSIONS

These results suggest that the anatomical distribution of VF differs between children and adults, perhaps relating to the different shape of the immature spine, notably the changing ratio of kyphosis to lordosis.

Skeletal findings in children recently initiating glucocorticoids for the treatment of nephrotic syndrome

SUMMARY

Eighty children with nephrotic syndrome underwent lumbar spine densitometry and vertebral morphometry soon after glucocorticoid initiation. We found an inverse relationship between glucocorticoid exposure and spine areal bone mineral density (BMD) Z-score and a low rate of vertebral deformities (8%).

INTRODUCTION

Vertebral fractures are an under-recognized complication of childhood glucocorticoid-treated illnesses. Our goal was to study the relationships among glucocorticoid exposure, lumbar spine areal BMD (LS BMD), and vertebral shape in glucocorticoid-treated children with new-onset nephrotic syndrome.

METHODS

Lateral thoracolumbar spine radiography and LS BMD were performed in 80 children with nephrotic syndrome (median age 4.4 years; 46 boys) within the first 37 days of glucocorticoid therapy. Genant semiquantitative grading was used as the primary method for vertebral morphometry; the algorithm-based qualitative (ABQ) method was used for secondary vertebral deformity analysis.

RESULTS

Six of the 78 children with usable radiographs (8%; 95% confidence interval 4 to 16%) manifested a single Genant grade 1 deformity each. All deformities were mild anterior wedging (two at each of T6, T7, and T8). Four of the 78 children (5%; 95% confidence interval 2 to 13%) showed one ABQ sign of fracture each (loss of endplate parallelism; two children at T6 and two at T8). Two of the children with ABQ signs also had a Genant grade 1 deformity in the same vertebral body. None of the children with a Genant or ABQ deformity reported back pain. An inverse relationship was identified between LS BMD Z-score and glucocorticoid exposure.

CONCLUSIONS

Although we identified an inverse relationship between steroid exposure and LS BMD soon after glucocorticoid initiation for childhood nephrotic syndrome, there was only a low rate of vertebral deformities. The clinical significance of these findings requires further study.

Alendronate for the treatment of pediatric osteogenesis imperfecta: a randomized placebo-controlled study

CONTEXT

Information on the use of oral bisphosphonate agents to treat pediatric osteogenesis imperfecta (OI) is limited.

OBJECTIVE

The objective of the investigation was to study the efficacy and safety of daily oral alendronate (ALN) in children with OI.

DESIGN AND PARTICIPANTS

We conducted a multicenter, double-blind, randomized, placebo-controlled study. One hundred thirty-nine children (aged 4-19 yr) with type I, III, or IV OI were randomized to either placebo (n = 30) or ALN (n = 109) for 2 yr. ALN doses were 5 mg/d in children less than 40 kg and 10 mg/d for those 40 kg and greater.

MAIN OUTCOME MEASURES

Spine areal bone mineral density (BMD) z-score, urinary N-telopeptide of collagen type I, extremity fracture incidence, vertebral area, iliac cortical width, bone pain, physical activity, and safety parameters were measured.

RESULTS

ALN increased spine areal BMD by 51% vs. a 12% increase with placebo (P < 0.001); the mean spine areal BMD z-score increased significantly from -4.6 to -3.3 (P < 0.001) with ALN, whereas the change in the placebo group (from -4.6 to -4.5) was insignificant. Urinary N-telopeptide of collagen type I decreased by 62% in the ALN-treated group, compared with 32% with placebo (P < 0.001). Long-bone fracture incidence, average midline vertebral height, iliac cortical width, bone pain, and physical activity were similar between groups. The incidences of clinical and laboratory adverse experiences were also similar between the treatment and placebo groups.

CONCLUSIONS

Oral ALN for 2 yr in pediatric patients with OI significantly decreased bone turnover and increased spine areal BMD but was not associated with improved fracture outcomes.

Prevalent vertebral fractures among children initiating glucocorticoid therapy for the treatment of rheumatic disorders

OBJECTIVE

Vertebral fractures are an under-recognized problem in children with inflammatory disorders. We studied spine health among 134 children (87 girls) with rheumatic conditions (median age 10 years) within 30 days of initiating glucocorticoid therapy.

METHODS

Children were categorized as follows: juvenile dermatomyositis (n = 30), juvenile idiopathic arthritis (n = 28), systemic lupus erythematosus and related conditions (n = 26), systemic arthritis (n = 22), systemic vasculitis (n = 16), and other conditions (n = 12). Thoracolumbar spine radiograph and dual x-ray absorptiometry for lumbar spine (L-spine) areal bone mineral density (BMD) were performed within 30 days of glucocorticoid initiation. Genant semiquantitative grading was used for vertebral morphometry. Second metacarpal morphometry was carried out on a hand radiograph. Clinical factors including disease and physical activity, calcium and vitamin D intake, cumulative glucocorticoid dose, underlying diagnosis, L-spine BMD Z score, and back pain were analyzed for association with vertebral fracture.

RESULTS

Thirteen vertebral fractures were noted in 9 children (7%). Of these, 6 patients had a single vertebral fracture and 3 had 2-3 fractures. Fractures were clustered in the mid-thoracic region (69%). Three vertebral fractures (23%) were moderate (grade 2); the others were mild (grade 1). For the entire cohort, mean +/- SD L-spine BMD Z score was significantly different from zero (-0.55 +/- 1.2, P < 0.001) despite a mean height Z score that was similar to the healthy average (0.02 +/- 1.0, P = 0.825). Back pain was highly associated with increased odds for fracture (odds ratio 10.6 [95% confidence interval 2.1-53.8], P = 0.004).

CONCLUSION

In pediatric rheumatic conditions, vertebral fractures can be present prior to prolonged glucocorticoid exposure.

Iliac bone histomorphometry in children with newly diagnosed inflammatory bowel disease

Children with inflammatory bowel disease (IBD) manifest low bone mass; the cause remains unclear. We performed transilial bone biopsies in 20 IBD children at diagnosis and found a mild cortical bone deficit and slow bone turnover. It is possible that low mechanical stimulation due to inadequate muscle mass contributes to the bone deficit.

INTRODUCTION

Children with newly diagnosed IBD can have low bone mineral density and disturbed bone metabolism, but the tissue level characteristics of the bone involvement in pediatric IBD have not been elucidated.

METHODS

In the present study, we evaluated the skeletal status, including static histomorphometry on transiliac bone samples, in 20 patients (age range 8.4 to 17.7 years, 12 boys) with newly diagnosed IBD and compared results to published normative data.

RESULTS

Despite normal height (mean Z-score 0.04, SD 1.2), areal bone mineral density at the lumbar spine was moderately low (mean age- and sex-specific Z-score -0.8, SD 1.1). Total body bone mineral content and lean mass were low for age and sex as well (mean Z-scores -1.2, SD 0.9 and -2.0, SD 0.9, respectively). Biochemical bone markers indicated low bone formation and resorption activity. Bone histomorphometry revealed a slightly low cortical width (mean 23%, SD 25%, below the result expected for age) but a normal amount of trabecular bone. The percentage of trabecular bone surface covered by osteoid or osteoclasts was low, suggesting that both bone formation and bone resorption were suppressed.

CONCLUSIONS

Our results indicate that young patients manifest a mild cortical bone deficit at the iliac crest and slow trabecular bone turnover even at diagnosis, in the setting of IBD.

Single-dose pharmacokinetics and tolerability of alendronate 35- and 70-milligram tablets in children and adolescents with osteogenesis imperfecta type I

CONTEXT

Alendronate (ALN) is a bisphosphonate compound that can be administered orally and has potential use in pediatric osteoporotic conditions.

OBJECTIVE

The objective was to evaluate the pharmacokinetics and single-dose tolerability of ALN in children with osteogenesis imperfecta.

DESIGN

ALN was administered iv and orally in a two-period, randomized crossover study, with doses separated by a 2-wk washout and follow-up carried out within 2 wk after the last ALN dose.

SETTING

The study was conducted at the pediatric metabolic bone research unit at the Shriners Hospital for Children, Montréal, Canada.

PATIENTS

Twenty-four children (aged 4-16 yr; eight girls) with osteogenesis imperfecta type I participated.

INTERVENTIONS

All patients received iv ALN at a dose of 125 mug. In addition, patients weighing less than 40 kg received an oral dose of ALN 35 mg, whereas those weighing 40 kg or more received ALN 70 mg orally.

MAIN OUTCOME MEASURES

Total urinary excretion and oral bioavailability of ALN, blood and urine safety parameters, and adverse events were the main outcome measures.

RESULTS

The total urinary excretion of ALN after the iv dose was similar for both weight groups. The mean oral bioavailability (95% confidence interval) was 0.43% (0.28, 0.64%) for patients weighing less than 40 kg and 0.56% (0.36, 0.87%) for patients weighing 40 kg or more. Eighteen patients reported a total of 44 clinical adverse experiences, none of which were serious. The most common adverse experiences were mild to moderate headache (n = 7), nausea (n = 7), fever (n = 5), and abdominal pain (n = 6). Eighty percent of the adverse experiences (35 of 44) occurred within 48 h of medication administration, 91% (40 of 44) lasted less than 24 h, and 84% (37 of 44) were reported after oral dosing. Laboratory safety monitoring revealed a marginal decrease in absolute lymphocyte count and serum alkaline phosphatase after the study compared with baseline for both weight categories.

CONCLUSIONS

The mean oral bioavailability of 35- and 70-mg ALN tablets was less than 0.6%, comparable to adult studies. Adverse experiences from single-dose ALN were minor, and the drug was generally well-tolerated.

Osteopathia striata with cranial sclerosis: clinical, radiological, and bone histological findings in an adolescent girl

Osteopathia striata with cranial sclerosis (OS-CS) is a rare skeletal dysplasia characterized by linear striations of the long bones, osteosclerosis of the cranium, and extra-skeletal anomalies. We provide a comprehensive description of the skeletal phenotype in a French-Canadian girl with a moderate to severe form of sporadic OS-CS. Multiple medical problems, including anal stenosis and the Pierre-Robin sequence, were evident in the first few years of life. At 14 years, she was fully mobile, with normal intellect and stature. She suffered chronic lower extremity pain in the absence of fractures, as well as severe headaches, unilateral facial paralysis, and bilateral mixed hearing loss. Biochemical indices of bone and mineral metabolism were within normal limits. Bone densitometry showed increased areal bone mineral density in the skull, trunk, and pelvis, but not in the upper and lower extremities. An iliac bone biopsy specimen revealed an increased amount of trabecular bone. Trabeculae were abnormally thick, but there was no evidence of disturbed bone remodeling. In a cranial bone specimen, multiple layers of periosteal bone were found that covered a compact cortical compartment containing tightly packed haversian canals. Bone lamellation was normal in both the iliac and skull samples. Osteoclast differentiation studies showed that peripheral blood osteoclast precursors from this patient formed functional osteoclasts in vitro. Thus, studies of bone metabolism did not explain why bone mass is increased in most skeletal areas of this patient. Cranial histology points to exuberant periosteal bone formation as a potential cause of the cranial sclerosis.

Resolution of severe, adolescent-onset hypophosphatemic rickets following resection of an FGF-23-producing tumour of the distal ulna

Oncogenic hypophosphatemic osteomalacia (OHO) is an uncommon hypophosphatemic syndrome characterized by bone pain, proximal muscle weakness and rickets. It has been postulated that OHO results from overproduction of a humoral phosphaturic factor by an occult tumour. Recently, some OHO tumours have been shown to elaborate fibroblast growth factor-23 (FGF-23), which causes renal phosphate wasting when administered to mice. The purpose of this study was to undertake detailed investigations to confirm the diagnosis of OHO in a pediatric patient and to document the biochemical, radiographic and bone histological phenotype before and after tumour removal. We describe an 11-year-old, previously healthy girl with significant pain and functional disability associated with hypophosphatemic rickets. Circulating 1,25-(OH)(2) vitamin D was very low (14 pM; N: 40-140) while the FGF-23 serum level was markedly elevated [359.5 reference units (RU)/ml, N: 33-105]. An iliac bone biopsy revealed severe osteomalacia, but periosteocytic lesions, as are typical for X-linked hypophosphatemic rickets, were not seen. Sequence analyses of the PHEX and FGF23 genes were normal. A radiographic skeletal survey revealed a small exostosis of the left, distal ulnar metaphysis. A tumour was subsequently removed from this site and the pathology was consistent with benign, fibro-osseous tissue. Serum FGF-23 was normal when measured at 7 h post-operatively, while serum phosphate reached the low-normal range at 16 days following surgery. An iliac bone biopsy taken 5 months after the operation showed improvement, but not yet resolution, of the osteomalacia. Biochemical parameters of bone and mineral metabolism suggested that complete resolution of the osteomalacia was not achieved until 12 months following surgery. One year after tumour removal, the patient was pain-free and had resumed a normal level of activity. The rapid normalization of FGF-23 levels following removal of a benign tumour and the subsequent improvement in the biochemical and histological parameters of bone and mineral metabolism suggest that FGF-23 played a key role in this girl's disease.

Genetic changes in the RNA components of RNase MRP and RNase P in Schmid metaphyseal chondrodysplasia

BACKGROUND

The Schmid type of metaphyseal chondrodysplasia (MCDS) is generally due to mutations in COL10A1 encoding for type X collagen of cartilage.

METHODS

We performed a study on the genes coding for the RNA components of RNase MRP (MRPR) and RNase P (H1RNA) among 20 patients with diagnosis of MCDS and no mutations in COL10A1.

RESULTS

Two patients were found to be homozygous for a base substitution G for A at nucleotide 70 of RMRP, which is the major mutation causing cartilage-hair hypoplasia. No pathogenic mutations were detected in H1RNA.

CONCLUSION

Cartilage-hair hypoplasia diagnosis should be considered in patients with metaphyseal chondrodysplasia even in the absence of any extra-skeletal manifestations if no mutation in COL10A1 can be found and the family history is compatible with autosomal recessive inheritance. Correct diagnosis is important for genetic counselling and for proper follow up of the patients.

Osteogenesis imperfecta type VII maps to the short arm of chromosome 3

We have identified a novel form of autosomal recessive osteogenesis imperfecta (OI) in a small First Nations community from northern Quebec. Mutation screening of the COL1A1/COL1A2 genes revealed no detectable mutations, and type I collagen protein analyses were also normal. By linkage analysis, we mapped this unique autosomal recessive variant of osteogenesis imperfecta to chromosome 3p22-24.1. Based on the assumption of a founder effect, genome-wide screening was performed on a DNA sample pooled from seven affected individuals. Familial as well as historical recombinations identified within an extended haplotype of 19 markers localized the disease between markers D3S2324 and D3S1561, separated by <5 cM. Based on chromosomal localization to 3p22-24.1, the transforming growth factor-beta receptor 2 gene and the parathyroid hormone/parathyroid hormone-related peptide receptor were tested, but were excluded as being associated with the phenotype. This study excludes type I collagen mutations in the pathogenesis of the disease and assigns this form of OI to a locus other than the ones containing the type I collagen genes.

Osteogenesis imperfecta type VII: an autosomal recessive form of brittle bone disease

Osteogenesis imperfecta (OI) is a heritable disease of bone with low bone mass and bone fragility. The disease is generally classified into four types based on clinical features and disease severity, although recently fifth and sixth forms have also been reported. Most forms of OI are autosomal dominant. Rarely, autosomal recessive disease has been described. We report the clinical, radiological, and histological features of four children (age 3.9-8.6 years at last follow-up; all girls) and four adults (age 28-33 years; two women) with a novel form of autosomal recessive OI living in an isolated First Nations community in northern Quebec. In keeping with the established numeric classification for OI forms, we have called this form of the disease OI type VII. The phenotype is moderate to severe, characterized by fractures at birth, bluish sclerae, early deformity of the lower extremities, coxa vara, and osteopenia. Rhizomelia is a prominent clinical feature. Histomorphometric analyses of iliac crest bone samples revealed findings similar to OI type I, with decreased cortical width and trabecular number, increased bone turnover, and preservation of the birefringent pattern of lamellar bone. The disease has subsequently been localized to chromosome 3p22-24.1, which is outside the loci for type I collagen genes. The underlying genetic basis for the disease remains to be determined.

Transient spatial attention modulates distinct components of the auditory ERP

We recorded ERPs to pairs of externally presented tones, T1 and T2, in the absence of attentional cues to determine whether attention is momentarily sustained at the location of a behaviourally relevant sound, and what effect this focusing of attention might have on the neural response to target stimuli. ERPs to T2 were more negative when the preceding T1 was presented on the same side of fixation than when T1 was presented on the opposite side of fixation. This negative difference consisted of an early, parietal phase and a later, frontocentral phase. These results confirm and extend previously reported effects of transient spatial attention on auditory ERPs, and they demonstrate that transient spatial attention has a distinct and robust effect on the early stages of stimulus processing in the auditory system.

Thirty-three novel COL1A1 and COL1A2 mutations in patients with osteogenesis imperfecta types I-IV

Osteogenesis imperfecta (OI) is a heritable disease of bone characterized by low bone mass and bone fragility. Six different types of OI have been described to date, based on clinical phenotype and histological findings. The genetic defect in many patients with OI types I-IV is due to mutations in the genes encoding type I collagen, while patients with OI types V and VI show no evidence of mutations in the COL1A1/COL1A2 genes. Here we report thirty-three novel mutations in patients with types I-IV OI. Sixteen mutations were in COL1A1 and seventeen were in COL1A2. Most mutations resulted in substitutions for glycine: one of these, a doublet GG>CC transversion, created a unique Gly-->Pro missense mutation in the triple helical domain of COL1A2. Two rare triple helical Gly-->Glu substitutions in COL1A2 are also described. In addition, there were six single-base deletion mutations resulting in frameshifts, seven splice junction mutations, and a 9-bp triple helix insertion associated with a severe (OI II) phenotype. The variety of mutations described in the COL1A1/COL1A2 genes giving rise to an OI phenotype is in accordance with the clinical heterogeneity of the disease. Hum Mutat 17:434, 2001.

On asymmetries in cross-modal spatial attention orienting

In a previous study, Ward (1994) reported that spatially uninformative visual cues orient auditory attention but that spatially uninformative auditory cues fail to orient visual attention. This cross-modal asymmetry is consistent with other intersensory perceptual phenomena that are dominated by the visual modality (e.g., ventriloquism). However, Spence and Driver (1997) found exactly the opposite asymmetry under different experimental conditions and with a different task. In spite of the several differences between the two studies, Spence and Driver (see also Driver & Spence, 1998) argued that Ward's findings might have arisen from response-priming effects, and that the cross-modal asymmetry they themselves reported, in which auditory cues affect responses to visual targets but not vice versa, is in fact the correct result. The present study investigated cross-modal interactions in stimulus-driven spatial attention orienting under Ward's complex cue environment conditions using an experimental procedure that eliminates response-priming artifacts. The results demonstrate that the cross-modal asymmetry reported by Ward (1994) does occur when the cue environment is complex. We argue that strategic effects in cross-modal stimulus-driven orienting of attention are responsible for the opposite asymmetries found by Ward and by Spence and Driver (1997).

Stochastic resonance enhances the electrosensory information available to paddlefish for prey capture

Recent behavior experiments have demonstrated that paddlefish can make use of stochastic resonance while feeding on Daphnia plankton. Here we calculate the information content of the noisy Daphnia signal at the paddlefish rostrum using an exact statistical treatment of threshold stochastic resonance as a minimal neural model. These calculations compare well with experimentally obtained data on paddlefish strikes at Daphnia prey.

Stochastic resonance in a statistical model of a time-integrating detector

We study an optimal nonparametric regression model for a threshold detector exposed to a noisy, subthreshold signal. The problem of recovering the signal is similar to that faced by neurons in nervous systems, although our model is intended to be normative rather than realistic. In our approach, the time-integrating activity of the neuron is modeled by kernel regression. Several aspects of the performance of the model are studied, including the existence of an optimal amount of noise (stochastic resonance). We construct a sequential, data-driven procedure for estimating the subthreshold signal. The performance of our model for threshold data is compared with kernel estimation for fully observed data. Finally, we discuss differences between our estimator and the best estimator for a constant signal.

Involuntary listening aids seeing: evidence from human electrophysiology

It is well known that sensory events of one modality can influence judgments of sensory events in other modalities. For example, people respond more quickly to a target appearing at the location of a previous cue than to a target appearing at another location, even when the two stimuli are from different modalities. Such cross-modal interactions suggest that involuntary spatial attention mechanisms are not entirely modality-specific. In the present study, event-related brain potentials (ERPs) were recorded to elucidate the neural basis and timing of involuntary, cross-modal spatial attention effects. We found that orienting spatial attention to an irrelevant sound modulates the ERP to a subsequent visual target over modality-specific, extrastriate visual cortex, but only after the initial stages of sensory processing are completed. These findings are consistent with the proposal that involuntary spatial attention orienting to auditory and visual stimuli involves shared, or at least linked, brain mechanisms.

Constrained scaling: the effect of learned psychophysical scales on idiosyncratic response bias

We report seven experiments in which subjects were trained to respond with numbers to the loudness of 1000-Hz pure tones according to power functions with exponents of 0.60, 0.30, and 0.90. Subjects were then presented with stimuli from other continua (65-Hz pure tones or 565-nm lights varying in amplitude) and were asked to judge the subjective magnitude of these stimuli on the same numerical scale. Stimuli from the training continuum were presented, with feedback, on every other trial in order to maintain the trained scale. Except for the 0.90 scale, subjects readily learned the predetermined scales and were able to use them to judge the non-training stimuli with group results consistent with those usually reported. Also, in contrast to the usual magnitude estimation results, these results produced extremely low levels of intersubject variability. We argue that such learned scales can be used as "rulers" for measuring perceived magnitudes, according to a common unit.

An event-related brain potential study of inhibition of return

Event-related brain potentials (ERPs) were recorded during two spatial-cuing experiments using nonpredictive cues. Our primary goal was to determine the electrophysiological consequences of inhibition of return (IOR). At long (> 500 msec) cue-target intervals, subjects responded more slowly to targets that appeared at or near the cued location, relative to targets that appeared on the opposite side of fixation from the cue. This behavioral IOR effect was associated with cue-validity effects on several components of the target-elicited ERP waveforms. The earliest such effect was a smaller occipital P1 on valid-cue trials, which we interpret as a P1 reduction. The P2 component was also smaller on valid-cue trials, indicating that nonpredictive spatial cues influence multiple stages of information processing at long cue-target intervals. Both of these effects were observed when sensory interactions between cue and target were likely to be negligible, indicating that they were not caused by sensory refractoriness. A different effect of cue validity, the posterior negative difference, was found when sensory interactions were likely to be greatest, indicating that it could arise from sensory refractoriness.

Statistical analysis of stochastic resonance in a simple setting

A subthreshold signal may be detected if noise is added to the data. We study a simple model, consisting of a constant signal to which at uniformly spaced times independent and identically distributed noise variables with known distribution are added. A detector records the times at which the noisy signal exceeds a threshold. There is an optimal noise level, called stochastic resonance. We explore the detectability of the signal in a system with one or more detectors, with different thresholds. We use a statistical detectability measure, the asymptotic variance of the best estimator of the signal from the thresholded data, or equivalently, the Fisher information in the data. In particular, we determine optimal configurations of detectors, varying the distances between the thresholds and the signal, as well as the noise level. The approach generalizes to nonconstant signals.

Memory for psychophysical scaling judgments

In three experiments, we examined memory for responses and stimuli experienced in a single direct psychophysical scaling session in which subjects made absolute magnitude estimations of the loudnesses of pure tones. Recall of scaling responses was found to be accurate for the softest and loudest stimuli, but systematically greater than actual judgments for the intermediate stimulus amplitudes, yielding distorted psychophysical functions for the recall data which nonetheless had the same power function exponent as that for the judged stimuli. Also, memory for the range of stimulus amplitudes was fairly accurate, but subjects could not distinguish between judged and nonjudged amplitudes within that range. The results are consistent with the role of extreme stimuli as anchors for judgment, and indicate that memories for these stimuli and responses made to them can be expected to influence future scaling judgments. These results also are consistent with the uncertainty hypothesis of mnemophysics.

Metaphors and the mental lexicon

In two experiments we investigate the possibility that lexicalization can account for the distinction between literal and metaphorical language. In both experiments, sentence contexts were presented with the final word missing. When subjects signaled they understood the context, two possible final words were presented and subjects were required to decide which was more appropriate. Semantic decision times over five different types of stimuli investigating literal and metaphorical word usage were consistent with a modified class inclusion model in which both the lexicalized meaning of words and the context in which they are presented make essential contributions to understanding.

Effects of cGMP and the nitric oxide donors glyceryl trinitrate and sodium nitroprusside on contractions in vitro of isolated myometrial tissue from pregnant women

The purpose of this study was to determine the relaxant effects in vitro of two nitric oxide donors, glyceryl trinitrate and sodium nitroprusside, which are currently available for use in vivo, on contractions of non-labouring myometrium from pregnant women. Since nitric oxide also mediates relaxation by increasing the concentration of cGMP, sensitivity to 8-bromo-cGMP (a cGMP analogue) was also determined. The effects of the K(+)-channel opener lemakalim and of the Ca(2+)-channel blocker nifedipine were studied for comparison. After the addition of glyceryl trinitrate (0.1-100 mumol l-1), sodium nitroprusside (0.1-100 mumol l-1) or 8-bromo-cGMP (0.001-3 mmol l-1), the spontaneous rhythmic contractility of myometrial strips was inhibited in a concentration-dependent manner: the maximum inhibition produced by the highest tested concentration of each drug was 40 +/- 7%, 53 +/- 8% and 39 +/- 8% of the original degree of contraction, respectively. Myometrial contractions were completely abolished by lemakalim and by nifedipine and verapamil at concentrations of > or = 10(-5) mol l-1. The nitric oxide donors, glyceryl trinitrate and sodium nitroprusside, attenuate myometrial contractions and are therefore useful as tocolytic agents. However, at equimolar concentrations in vitro, the ability of glyceryl trinitrate and sodium nitroprusside to attenuate myometrial contractions is less than that of lemakalin, nifedipine and verapamil. Controlled trials are required to determine the side-effects and clinical efficacy of each of these agents in vivo.

Attention cueing aids auditory intensity resolution

Intensity resolution of pure tones in a one-interval forced-choice paradigm was measured for experienced musicians under fixed- and uncertain-frequency conditions, and under uncertain-frequency conditions with informative cues as to target frequency. The uncertain frequency effect for intensity resolution, when present, was reduced or removed by frequency cueing, both with auditory stimulus cues and with visually presented information cues. Also, intensity resolution performance improved over the course of the experiment, both for fixed- and for uncertain-frequency conditions, as had been found previously. Analysis of the individual data indicated that across-experiment learning was unrelated to the ability to use the auditory stimulus cue, and that multiple-band learning was incompatible with the use of the visual information cue. The results are consistent with the idea that the single-band listening observed in fixed-frequency conditions was induced in most listeners by the auditory stimulus cue, but that some listeners chose to use the visual information cue to single-band listen while others ignored it and used multiple-band listening in that condition.

Intensity resolution and subjective magnitude in psychophysical scaling

Several successful theories of psychophysical judgment imply that exponents of power functions in scaling tasks should covary with measures of intensity resolution such as d' in the same tasks, whereas the prevailing metatheory of ideal psychophysical scaling asserts the independence of the two. In a direct test of this relationship, three prominent psychophysical scaling paradigms were studied: category judgment without an identification function, absolute magnitude estimation, and cross-modality matching with light intensity as the response continuum. Separate groups of subjects for each scaling paradigm made repeated judgments of the loudnesses of the pure tones that constituted each of two stimulus ensembles. The narrow- and wide-range ensembles shared six identical stimulus intensities in the middle of each set. Intensity resolution, as measured by d'-like distances, of these physically identical stimuli was significantly worse for the wide-range set for all three methods. Exponents of power functions fitted to geometric mean responses, and in magnitude estimation and cross-modality matching the geometric mean responses themselves, were also significantly smaller in the wide-range condition. The variation of power function exponents, and of psychophysical scale values, for stimulus intensities that were identical in the two stimulus sets with the intensities of other members of the ensembles is inconsistent with the metatheory on which modern psychophysical scaling practice is based, although it is consistent with other useful approaches to measurement of psychological magnitudes.

Pure feedback effects in absolute identification

To reveal the pure effects of trial-by-trial feedback on judgmental accuracy and sequential dependencies independent of global anchoring effects and other influences, we presented subjects with sequences consisting alternately (within an experimental session) of short runs of trials with feedback (feedback sequences) and without feedback (no-feedback sequences). In Experiments 1 and 2 (absolute identification of sound intensity and sound frequency, respectively), judgmental accuracy was the same in the feedback and the no-feedback sequences, contrary to previous results. Also, in the feedback sequences, the dependency of the current response on the immediately preceding stimulus was larger than that in the no-feedback sequences, while the dependency on the previous response was larger in the no-feedback sequences. In Experiment 3 (absolute identification of sound frequency), we attempted to separate the effects of the number of response categories on sequential dependencies from the effects of the number of stimuli. The results showed that the number of response categories had a larger effect than the number of stimuli on most aspects of performance, but that both affected sequential dependencies. These results are generally consistent with a theory of absolute identification in which feedback affects judgmental accuracy by improving long-term memory for judgmental anchors, while feedback affects sequential dependencies by altering response biases.

Supramodal and modality-specific mechanisms for stimulus-driven shifts of auditory and visual attention

Two experiments are described in which visual and/or auditory location precues preceded visual or auditory targets. Observers were required to judge the location of the targets. Conditions were such that involuntary, stimulus-driven attention shifts were the only ones likely to occur and give rise to cueing effects. It was found that visual precues affected response time to localize both visual targets and auditory targets but auditory precues affected only the time to localize auditory targets. Moreover, when visual and auditory cues conflicted, visual cues dominated in the visual task but were dominated by auditory cues in the auditory task. These results imply that involuntary stimulus-driven attention shifts might be controlled by a modality-specific mechanism for visual tasks, whereas stimulus-driven shifts of auditory attention are controlled by a supramodal mechanism. This asymmetry in attention control is consistent with the idea that attentional dominance in a multimodal experimental task depends on the relative performance possible in the modalities involved; in this case visual localization is more precise than auditory and so auditory cues may be ineffective in cueing visual location, while visual cues are effective in both modalities.

Where the action is: Weber fractions as a function of sound pressure at low frequencies

Weber fractions for sound intensity were measured for 70-, 100-, 200-, 1000-, and 10,000-Hz tone pulses at sound-pressure levels (SPLs) ranging from just above individual listeners' absolute thresholds to near their highest tolerable SPLs, using a two-alternative forced-choice adaptive staircase technique governed by a 1-up, 3-down rule. Results for four listeners with normal hearing and varying experience, despite individual differences in absolute values, showed Weber fractions that declined as sound pressure increased above threshold and asymptoted at intermediate SPLs. A power function with a negative exponent describes the data of the individual listeners better than a logarithmic function does. The absolute value of the exponent of the power function, which measures the curvature of the function, was largest at 70 Hz and declined with increasing frequency, similar to how exponents of power functions relating loudness judgments or simple reaction time to stimulus intensity differ with sound frequency.

Expression of epidermal growth factor receptor in human glioblastoma multiforme

The expression of epidermal growth factor receptor was determined in a series of 88 patients with glioblastoma multiforme using a monoclonal antibody to the receptor. Positive staining was seen in 17 patients but this did not have prognostic significance when compared with known clinical prognostic factors using a computer model. The significance of receptor expression in these tumours is discussed.