Tracking the emergence of an organized use of space: A direct comparison of the spatial patterning within Middle and Upper Paleolithic open-air sites

Although the 'organization of space' is said to be one of the defining characteristics of modern human behavior, the identification and documentation of such organization has proven to be elusive, especially as rendered in artifact patterning. Without directly comparing artifact patterns within multiple sites, there is no benchmark with which to conclude one site to be more or less 'organized' than another. We can objectively identify patterns within the distribution of archaeological materials, but the decision of whether that patterning constitutes as 'organized' is entirely subjective without a comparative model. In this paper, I present the results of a study in which the spatial distribution of artifacts within nine Middle and Upper Paleolithic sites in France are directly compared to one another, and discernible changes in patterning can be identified. The differences in spatial patterning between the Middle and Upper Paleolithic sites suggest that the organization of space likely became increasingly formalized into and throughout the Upper Paleolithic alongside other cultural norms of behavior. Though more sites are needed to thoroughly document this phenomenon, this study suggests that direct comparisons of spatial patterning have the potential to yield more objective results on the question of spatial organization.

Reducing Stress after Trauma (ReSeT): study protocol for a randomized, controlled trial of an online psychoeducational program and video therapy sessions for children hospitalized after trauma

BACKGROUND

Post-traumatic stress symptoms develop in a quarter to half of injured children affecting their longer-term psychologic and physical health. Evidence-based care exists for post-traumatic stress; however, it is not readily available in some communities. We have developed an eHealth program consisting of online, interactive educational modules and telehealth therapist support based in trauma-focused cognitive behavioral therapy, the Reducing Stress after Trauma (ReSeT) program. We hypothesize that children with post-traumatic stress who participate in ReSeT will have fewer symptoms compared to the usual care control group.

METHODS

This is a randomized controlled trial to test the effectiveness of the ReSeT intervention in reducing symptoms of post-traumatic stress compared to a usual care control group. One hundred and six children ages 8-17 years, who were admitted to hospital following an injury, with post-traumatic stress symptoms at 4 weeks post-injury, will be recruited and randomized from the four participating trauma centers. The outcomes compared across groups will be post-traumatic stress symptoms at 10 weeks (primary outcome) controlling for baseline symptoms and at 6 months post-randomization (secondary outcome).

DISCUSSION

ReSeT is an evidence-based program designed to reduce post-traumatic stress symptoms among injured children using an eHealth platform. Currently, the American College of Surgeons standards suggest that trauma programs identify and treat patients at high risk for mental health needs in the trauma system. If effectiveness is demonstrated, ReSeT could help increase access to evidence-based care for children with post-traumatic stress within the trauma system.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04838977. 8 April 2021.

Changing Healthcare and School Needs in the First Year After Traumatic Brain Injury

OBJECTIVE

To examine children's unmet and unrecognized healthcare and school needs following traumatic brain injury (TBI).

SETTING

Two pediatric trauma centers.

PARTICIPANTS

Children with all severity of TBI aged 4 to 15 years.

DESIGN

Prospective cohort.

MAIN MEASURES

Caregivers provided child health and school service use 3 and 12 months postinjury. Unmet and unrecognized needs were categorized compared with norms on standardized physical, cognitive, socioemotional health, or academic competence measures in conjunction with caregiver report of needs and services. Modified Poisson models examined child and family predictors of unmet and unrecognized needs.

RESULTS

Of 322 children, 28% had unmet or unrecognized healthcare or school needs at 3 months, decreasing to 24% at 12 months. Unmet healthcare needs changed from primarily physical (79%) at 3 months to cognitive (47%) and/or socioemotional needs (68%) at 12 months. At 3 months, low social capital, preexisting psychological diagnoses, and 6 to 11 years of age predicted higher healthcare needs and severe TBI predicted higher school needs. Twelve months postinjury, prior inpatient rehabilitation, low income, and preexisting psychological diagnoses were associated with higher healthcare needs; family function was important for school and healthcare needs.

CONCLUSIONS

Targeted interventions to provide family supports may increase children's access to services.

As Time Goes by: Understanding Child and Family Factors Shaping Behavioral Outcomes After Traumatic Brain Injury

Objective: To model pre-injury child and family factors associated with the trajectory of internalizing and externalizing behavior problems across the first 3 years in children with pediatric traumatic brain injury (TBI) relative to children with orthopedic injuries (OI). Parent-reported emotional symptoms and conduct problems were expected to have unique and shared predictors. We hypothesized that TBI, female sex, greater pre-injury executive dysfunction, adjustment problems, lower income, and family dysfunction would be associated with less favorable outcomes. Methods: In a prospective longitudinal cohort study, we examined the level of behavior problems at 12 months after injury and rate of change from pre-injury to 12 months and from 12 to 36 months in children ages 4-15 years with mild to severe TBI relative to children with OI. A structural equation model framework incorporated injury characteristics, child demographic variables, as well as pre-injury child reserve and family attributes. Internalizing and externalizing behavior problems were indexed using the parent-rated Emotional Symptoms and Conduct Problems scales from the Strengths and Difficulties questionnaire. Results: The analysis cohort of 534 children [64% boys, M (SD) 8.8 (4.3) years of age] included 395 with mild to severe TBI and 139 with OI. Behavior ratings were higher after TBI than OI but did not differ by TBI severity. TBI, higher pre-injury executive dysfunction, and lower income predicted the level and trajectory of both Emotional Symptoms and Conduct Problems at 12 months. Female sex and poorer family functioning were vulnerability factors associated with greater increase and change in Emotional Symptoms by 12 months after injury; unique predictors of Conduct Problems included younger age and prior emotional/behavioral problems. Across the long-term follow-up from 12 to 36 months, Emotional Symptoms increased significantly and Conduct Problems stabilized. TBI was not a significant predictor of change during the chronic stage of recovery. Conclusions: After TBI, Emotional Symptoms and Conduct Problem scores were elevated, had different trajectories of change, increased or stayed elevated from 12 to 36 months after TBI, and did not return to pre-injury levels across the 3 year follow-up. These findings highlight the importance of addressing behavioral problems after TBI across an extended time frame.

Trajectories of Children's Executive Function After Traumatic Brain Injury

IMPORTANCE

Executive functions are critical for school and social success. Although these functions are adversely affected by pediatric traumatic brain injury (TBI), recovery patterns are not well established.

OBJECTIVE

To examine 3-year trajectories of selected children's executive functions after TBI.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study was conducted from January 22, 2013, to September 30, 2015, with 3-year follow-up at the level I pediatric trauma centers Primary Children's Hospital in Salt Lake City, Utah and Children's Memorial Hermann Hospital in Houston, Texas. Study participants included children aged 2 to 15 years with TBI or orthopedic injury (OI) who were treated at the participating hospitals. Children were consecutively recruited and stratified by injury severity and age group. A total of 625 children consented and completed a baseline survey; 559 (89%) children completed at least 1 follow-up and composed the analysis cohort. It was hypothesized that recovery would differ by injury severity, age at injury, and sex. Data analyses were performed from June to October 2019.

MAIN OUTCOMES AND MEASURES

Growth curve models examined the pattern of change in the Emotional Control, Inhibit, Working Memory, and Plan-Organize subscales of the Behavior Rating Inventory of Executive Function (BRIEF) or BRIEF-Preschool. For all BRIEF subscales, higher scores indicate worse symptoms, and a score of 65 or greater represents clinical impairment.

RESULTS

A total of 559 children (mean [SD] age, 8.6 [4.4] years; 356 boys [64%], 328 non-Hispanic White children [59%]) were included in the study: 155 (28%) children had mild TBI, 162 (29%) had complicated mild or moderate TBI, 90 (16%) had severe TBI, and 152 (27%) had OI. Growth curve trajectories varied by BRIEF subscale and injury severity. Overall, children with TBI did not return to their preinjury baseline, with a stepwise worsening of each outcome at 36 months by TBI severity compared with OI. Among children with severe TBI, trajectories accelerated fastest, indicating increased problems, from injury to 12 months for the Emotional Control (9.0 points; 95% CI, 6.0-11.9 points), Inhibit (3.6 points; 95% CI, 1.6-5.6 points), and Working Memory (7.0 points; 95% CI, 4.1-9.9 points) subscales. Their trajectories plateaued, with a secondary acceleration before 36 months for the Emotional Control and Working Memory subscales. Children with mild TBI had worse 36-month scores on all subscales except Inhibit compared with OI. Recovery patterns were similar for boys and girls.

CONCLUSIONS AND RELEVANCE

In this longitudinal cohort study of children with TBI, trajectory analysis revealed that some children worsen after a recovery plateau, suggesting a need for longitudinal reassessment beyond 1 year postinjury.

Latent Class Analysis to Classify Injury Severity in Pediatric Traumatic Brain Injury

Heterogeneity of injury severity among children with traumatic brain injury (TBI) classified by the Glasgow Coma Scale (GCS) makes comparisons across research cohorts, enrollment in clinical trials, and clinical predictions of outcomes difficult. The present study uses latent class analysis (LCA) to distinguish severity subgroups from a prospective cohort of 433 children 2.5-15 years of age with TBI who were recruited from two level 1 pediatric trauma centers. Indicator variables available within 48 h post-injury including emergency department (ED) GCS, hospital motor GCS, Abbreviated Injury Score (AIS), Rotterdam Score, hypotension in the ED, and pre-hospital loss of consciousness, intubation, seizures, and sedation were evaluated to define subgroups. To understand whether latent class subgroups were predictive of clinically meaningful outcomes, the Pediatric Injury Functional Outcome Scale (PIFOS) at 6 and 12 months, and the Behavior Rating Inventory of Executive Function at 12 months, were compared across subgroups. Then, outcomes were examined by GCS (primary) and AIS (secondary) classification alone to assess whether LCA provided improved outcome prediction. LCA identified four distinct increasing severity subgroups (1-4). Unlike GCS classification, mean outcome differences on PIFOS at 6 months showed decreasing function across classes. PIFOS differences relative to the lowest latent class (LC1) were: LC2 2.27 (0.83, 3.72), LC3 3.99 (1.88, 6.10), and LC4 11.2 (7.04, 15.4). Differences in 12 month outcomes were seen between the most and least severely injured groups. Differences in outcomes in relation to AIS were restricted to the most and less severely injured at both time points. This study distinguished four latent classes that are clinically meaningful, distinguished a more homogenous severe injury group, and separated children by 6-month functional outcomes better than GCS alone. Systematic reporting of these variables would allow comparisons across research cohorts, potentially improve clinical predictions, and increase sensitivity to treatment effects in clinical trials.

Factors influencing the survival of implant-supported ceramic-ceramic prostheses: A randomized, controlled clinical trial

OBJECTIVE

The goals of this research are: (1) to determine the clinical survival of ceramic-ceramic 3-unit implant supported fixed dental prostheses (FDPs) compared with control metal-ceramic and; (2) to analyze the effects of design parameters such as connector height, radius of curvature of gingival embrasure, and occlusal veneer thickness.

MATERIALS AND METHODS

This randomized, controlled clinical trial enrolled 96 participants with 129 3-unit implant-supported FDPs. Participants were randomized to receive different design combinations to include FDP material, thickness of occlusal veneer ceramic, radius of curvature of gingival embrasure and connector height. Participants were recalled for 6 months, 1year and yearly thereafter for the next 5 years. FDPs were examined for evidence of fracture and radiographs were made to assess viability of implants. Fractographic analyses and Kaplan Meier survival analysis was used to analyze the data.

RESULTS

27 FDPs, representing 21%, exhibited chipping fractures of the veneer during the 5-year observation period. There was no statistically significant effect of type of material, veneer thickness, radius of curvature of gingival embrasure and connector height on occurrence of fracture. Fractographic and occlusal analyses reveal that fractures originated from the occlusal surface and that occlusion was the most important factor in determining survival. Stresses calculated at failure demonstrated lower values compared with in vitro data.

CONCLUSION

Implant-supported ceramic-ceramic prosthesis is a viable alternative to metal-ceramic. Survival analysis for both materials were comparable and design parameters employed in this study did not affect survival as long as zirconia was used as the core material.

Persistent Postconcussion Symptoms After Injury

: media-1vid110.1542/5828371885001PEDS-VA_2018-0939Video Abstract OBJECTIVES: We examined whether preinjury, demographic, and family factors influenced vulnerability to postconcussion symptoms (PCSs) persisting the year after mild traumatic brain injury (mTBI).

METHODS

Children with mTBI (n = 119), complicated mild traumatic brain injury (cmTBI) (n = 110), or orthopedic injury (OI) (n = 118), recruited from emergency departments, were enrolled in a prospective, longitudinal cohort study. Caregivers completed retrospective surveys to characterize preinjury demographic, child, and family characteristics. PCSs were assessed using a validated rating scale. With multivariable general linear models adjusted for preinjury symptoms, we examined predictors of PCSs 3, 6, and 12 months after injury in children ages 4 to 8, 9 to 12, and 13 to 15 years at injury. With logistic regression, we examined predictors of chronic PCSs 1 year after traumatic brain injury.

RESULTS

Postinjury somatic, emotional, cognitive, and fatigue PCSs were similar in the mTBI and cmTBI groups and significantly elevated compared with the OI group. PCS trajectories varied with age and sex. Adolescents had elevated PCSs that improved; young children had lower initial symptoms and less change. Despite similar preinjury PCSs, girls had elevated symptoms across all time points compared with boys. PCS vulnerability factors included female sex, adolescence, preinjury mood problems, lower income, and family discord. Social capital was a protective factor. PCSs persisted in 25% to 31% of the traumatic brain injury group and 18% of the OI group at 1 year postinjury. The odds of chronic PCSs were almost twice as high in girls as in boys and were >4 times higher in young children with cmTBI than in those with mTBI.

CONCLUSIONS

A significant minority of children with mTBI and OI have PCSs that persisted 1 year after injury.

Longitudinal Developmental Outcomes after Traumatic Brain Injury in Young Children: Are Infants More Vulnerable Than Toddlers?

Children under 4 years of age have the highest incidence of traumatic brain injury (TBI) among the non-elderly and may be at high risk of poor developmental outcomes. We prospectively enrolled a cohort of children injured before 31 months old with TBI or orthopedic injury (OI), from 2013 to 2015 at two pediatric level 1 trauma centers to study very young children's developmental outcomes after injury. We used Ages & Stages-3 and Ages & Stages: Social-Emotional screening tools to measure children's development at pre-injury and 3 and 12 months post-injury. The cohort included 123 children with TBI categorized as mild (n = 48), complicated-mild or moderate (n = 54), and severe (n = 21) and 45 children with OI. Generalized linear models examined effects of injury severity and age at injury controlling for pre-injury ratings. Children with mild or complicated-mild/moderate TBI generally remained on developmental track. Compared to OI, children with severe TBI tended to have a negative developmental trajectory with decrements in communication (-7.07; 95% confidence interval [CI], -13.7, -0.48), gross motor (-15.2; 95% CI, -21.1, -9.19), problem solving (-11.6; 95% CI, -17.9, -5.29), personal-social (-16.8; 95% CI, -22.8, -10.8), and social-emotional (21.0; 95% CI, 7.32, 34.7) domains 12 months post-injury. Developmental effects from TBI differed by age at injury: Infants had more difficulties than older children in communication and problem-solving domains. Despite low developmental scores in 28% of the cohort, only 5% were receiving Early Childhood Intervention (ECI) services 12 months after injury. Early age at injury is a vulnerability factor after TBI. Young age and severe injury should prompt evaluation for ECI.

A homoleptic chromium(iii) carboxylate

Structurally characterized chromium(iii) carboxylates form clusters with a variety of bridging groups introduced from aqueous reaction conditions. The first homoleptic monomeric chromium(iii) carboxylate has been prepared using an anhydrous salt metathesis synthetic route. The carboxylate groups coordinate the chromium in a bidentate chelate yielding an aliphatic soluble complex. The complex was characterized by a variety of methods including high energy X-ray diffraction, FD-MS, IR and Raman spectroscopy, complemented by DFT modeling.

Cognitive Development One Year After Infantile Critical Pertussis

OBJECTIVES

Pertussis can cause life-threatening illness in infants. Data regarding neurodevelopment after pertussis remain scant. The aim of this study was to assess cognitive development of infants with critical pertussis 1 year after PICU discharge.

DESIGN

Prospective cohort study.

SETTING

Eight hospitals comprising the Eunice Kennedy Shriver National Institute for Child Health and Human Development Collaborative Pediatric Critical Care Research Network and 18 additional sites across the United States.

PATIENTS

Eligible patients had laboratory confirmation of pertussis infection, were less than 1 year old, and were admitted to the PICU for at least 24 hours.

INTERVENTIONS

The Mullen Scales of Early Learning was administered at a 1-year follow-up visit. Functional status was determined by examination and parental interview.

MEASUREMENTS AND MAIN RESULTS

Of 196 eligible patients, 111 (57%) completed the Mullen Scales of Early Learning. The mean scores for visual reception, receptive language, and expressive language domains were significantly lower than the norms (p < 0.001), but not fine and gross motor domains. Forty-one patients (37%) had abnormal scores in at least one domain and 10 (9%) had an Early Learning Composite score 2 or more SDs below the population norms. Older age (p < 0.003) and Hispanic ethnicity (p < 0.008) were associated with lower mean Early Learning Composite score, but presenting symptoms and PICU course were not.

CONCLUSIONS

Infants who survive critical pertussis often have neurodevelopmental deficits. These infants may benefit from routine neurodevelopmental screening.

Randomized clinical study of wear of enamel antagonists against polished monolithic zirconia crowns

OBJECTIVES

To test the hypothesis that there is no difference in the in vivo maximum wear of enamel opposing monolithic zirconia crowns, enamel opposing porcelain fused to metal crowns and enamel opposing enamel.

METHODS

Thirty patients needing single crowns were randomized to receive either a monolithic zirconia or metal-ceramic crown. Two non-restored opposing teeth in the same quadrants were identified to serve as enamel controls. After cementation, quadrants were scanned for baseline data. Polyvinylsiloxane impressions were obtained and poured in white stone. Patients were recalled at six-months and one-year for re-impression. Stone models were scanned using a tabletop laserscanner to determine maximum wear. Statistical analysis was performed using Mann-Whitney U to determine any significant differences between the wear of enamel against zirconia and metal-ceramic crowns.

RESULTS

Sixteen zirconia and 14 metal-ceramic crowns were delivered. There were no statistical differences in mean wear of crown types (p=0.165); enamel antagonists (p=0.235) and enamel controls (p=0.843) after one year.

CONCLUSION

Monolithic zirconia exhibited comparable wear of enamel compared with metal-ceramic crowns and control enamel after one year.

SIGNIFICANCE

This study is clinically significant because the use of polished monolithic zirconia demonstrated comparable wear of opposing enamel to metal-ceramic and enamel antagonists.

Psychosocial and Executive Function Recovery Trajectories One Year after Pediatric Traumatic Brain Injury: The Influence of Age and Injury Severity

Time since traumatic brain injury (TBI) and developmental stage at injury may affect the trajectory of outcomes associated with adjustment and school success. We prospectively enrolled a cohort of 519 children with either TBI or orthopedic injury (OI) age 2.5-15 years to examine children's psychosocial and executive function outcomes at 3- and 12-months post-injury. Outcome measures included the Child Behavior Checklist (CBCL), Strengths and Difficulties Questionnaire (SDQ), and Behavior Rating Inventory of Executive Function (BRIEF) ratings. Controlling for pre-injury ratings and using the OI group as the reference, children with TBI, regardless of age or injury severity, had affective, anxiety, and attention-deficit/hyperactivity disorder (ADHD) problems on the CBCL. Symptom trajectories differed both by injury severity and age at injury. Children with mild and complicated mild TBI had a decreasing anxiety trajectory, whereas children with severe TBI had increasing symptoms. Children 6-11 years of age had high ADHD and affective scores; however, the youngest children had increasing symptoms over time. On the SDQ, peer relationships and prosocial behaviors were not significantly affected by TBI but were associated with family environment. Children with severe TBI had the worst executive function scores; however, mild and complicated mild/moderate TBI groups had clinically important working memory deficits. Hispanic ethnicity and strong social capital were positively associated with multiple outcomes. Children's recovery trajectories differed by injury severity, time since injury, and developmental stage when injured. Schools need to reassess children's skills over time as new problems in behavior and learning may emerge.

Novel Testing for Corrosion of Glass-Ceramics for Dental Applications

The effects of pH cycling immersion on the corrosion of glass-based ceramic materials were investigated by examining the silicon release level in the immersion solution and the surface morphology of the ceramic after immersion. The hypothesis that pH cycling causes more surface degradation than constant immersion was tested. An inductively coupled plasma atomic emission spectrometer was used for Si ion concentration determination and scanning electron microscopy for surface morphology analyses. Two pH cycling sequences (pH 2, 7, 10 and pH 10, 2, 7) were employed in this study. Glass-ceramic disks were immersed in each pH solution for 3 d, then cycled for 27 d. The silicon release levels during the pH cycling were significantly higher than those in the constant pH immersion. The silicon levels for both cycling sequences were around 47 and 2 times higher than that in constant pH conditions for 2 and 10, respectively. The morphology of the ceramic treated with cycling was also significantly degraded as compared with the ceramic immersed in the constant pH solution. Thus, the severity of glass-ceramic degradation depends not only on the pH of the immersed solution but also on the pH of the previous solution. Since the pH of the oral environment can vary depending on the diet and buffering capacity of saliva, materials testing in constant pH immersion might underestimate the in vivo corrosion. New mechanisms were proposed to account for the effect of pH cycling on glass-ceramic corrosion.

Therapeutic Hypothermia after In-Hospital Cardiac Arrest in Children

BACKGROUND

Targeted temperature management is recommended for comatose adults and children after out-of-hospital cardiac arrest; however, data on temperature management after in-hospital cardiac arrest are limited.

METHODS

In a trial conducted at 37 children's hospitals, we compared two temperature interventions in children who had had in-hospital cardiac arrest. Within 6 hours after the return of circulation, comatose children older than 48 hours and younger than 18 years of age were randomly assigned to therapeutic hypothermia (target temperature, 33.0°C) or therapeutic normothermia (target temperature, 36.8°C). The primary efficacy outcome, survival at 12 months after cardiac arrest with a score of 70 or higher on the Vineland Adaptive Behavior Scales, second edition (VABS-II, on which scores range from 20 to 160, with higher scores indicating better function), was evaluated among patients who had had a VABS-II score of at least 70 before the cardiac arrest.

RESULTS

The trial was terminated because of futility after 329 patients had undergone randomization. Among the 257 patients who had a VABS-II score of at least 70 before cardiac arrest and who could be evaluated, the rate of the primary efficacy outcome did not differ significantly between the hypothermia group and the normothermia group (36% [48 of 133 patients] and 39% [48 of 124 patients], respectively; relative risk, 0.92; 95% confidence interval [CI], 0.67 to 1.27; P=0.63). Among 317 patients who could be evaluated for change in neurobehavioral function, the change in VABS-II score from baseline to 12 months did not differ significantly between the groups (P=0.70). Among 327 patients who could be evaluated for 1-year survival, the rate of 1-year survival did not differ significantly between the hypothermia group and the normothermia group (49% [81 of 166 patients] and 46% [74 of 161 patients], respectively; relative risk, 1.07; 95% CI, 0.85 to 1.34; P=0.56). The incidences of blood-product use, infection, and serious adverse events, as well as 28-day mortality, did not differ significantly between groups.

CONCLUSIONS

Among comatose children who survived in-hospital cardiac arrest, therapeutic hypothermia, as compared with therapeutic normothermia, did not confer a significant benefit in survival with a favorable functional outcome at 1 year. (Funded by the National Heart, Lung, and Blood Institute; THAPCA-IH ClinicalTrials.gov number, NCT00880087 .).

Therapeutic hypothermia after out-of-hospital cardiac arrest in children

BACKGROUND

Therapeutic hypothermia is recommended for comatose adults after witnessed out-of-hospital cardiac arrest, but data about this intervention in children are limited.

METHODS

We conducted this trial of two targeted temperature interventions at 38 children's hospitals involving children who remained unconscious after out-of-hospital cardiac arrest. Within 6 hours after the return of circulation, comatose patients who were older than 2 days and younger than 18 years of age were randomly assigned to therapeutic hypothermia (target temperature, 33.0°C) or therapeutic normothermia (target temperature, 36.8°C). The primary efficacy outcome, survival at 12 months after cardiac arrest with a Vineland Adaptive Behavior Scales, second edition (VABS-II), score of 70 or higher (on a scale from 20 to 160, with higher scores indicating better function), was evaluated among patients with a VABS-II score of at least 70 before cardiac arrest.

RESULTS

A total of 295 patients underwent randomization. Among the 260 patients with data that could be evaluated and who had a VABS-II score of at least 70 before cardiac arrest, there was no significant difference in the primary outcome between the hypothermia group and the normothermia group (20% vs. 12%; relative likelihood, 1.54; 95% confidence interval [CI], 0.86 to 2.76; P=0.14). Among all the patients with data that could be evaluated, the change in the VABS-II score from baseline to 12 months was not significantly different (P=0.13) and 1-year survival was similar (38% in the hypothermia group vs. 29% in the normothermia group; relative likelihood, 1.29; 95% CI, 0.93 to 1.79; P=0.13). The groups had similar incidences of infection and serious arrhythmias, as well as similar use of blood products and 28-day mortality.

CONCLUSIONS

In comatose children who survived out-of-hospital cardiac arrest, therapeutic hypothermia, as compared with therapeutic normothermia, did not confer a significant benefit in survival with a good functional outcome at 1 year. (Funded by the National Heart, Lung, and Blood Institute and others; THAPCA-OH ClinicalTrials.gov number, NCT00878644.).

'Fire at will': the emergence of habitual fire use 350,000 years ago

The use of fire is central to human survival and to the processes of becoming human. The earliest evidence for hominin use of fire dates to more than a million years ago. However, only when fire use became a regular part of human behavioral adaptations could its benefits be fully realized and its evolutionary consequences fully expressed. It remains an open question when the use of fire shifted from occasional and opportunistic to habitual and planned. Understanding the time frame of this 'technological mutation' will help explain aspects of our anatomical evolution and encephalization over the last million years. It will also provide an important perspective on hominin dispersals out of Africa and the colonization of temperate environments, as well as the origins of social developments such as the formation of provisioned base camps. Frequencies of burnt flints from a 16-m-deep sequence of archaeological deposits at Tabun Cave, Israel, together with data from the broader Levantine archaeological record, demonstrate that regular or habitual fire use developed in the region between 350,000-320,000 years ago. While hominins may have used fire occasionally, perhaps opportunistically, for some million years, we argue here that it only became a consistent element in behavioral adaptations during the second part of the Middle Pleistocene.

Recurrent and high-frequency use of the emergency department by pediatric patients

OBJECTIVES

The authors sought to describe the epidemiology of and risk factors for recurrent and high-frequency use of the emergency department (ED) by children.

METHODS

This was a retrospective cohort study using a database of children aged 0 to 17 years, inclusive, presenting to 22 EDs of the Pediatric Emergency Care Applied Research Network (PECARN) during 2007, with 12-month follow-up after each index visit. ED diagnoses for each visit were categorized as trauma, acute medical, or chronic medical conditions. Recurrent visits were defined as any repeat visit; high-frequency use was defined as four or more recurrent visits. Generalized estimating equations (GEEs) were used to measure the strength of associations between patient and visit characteristics and recurrent ED use.

RESULTS

A total of 695,188 unique children had at least one ED visit each in 2007, with 455,588 recurrent ED visits in the 12 months following the index visits. Sixty-four percent of patients had no recurrent visits, 20% had one, 8% had two, 4% had three, and 4% had four or more recurrent visits. Acute medical diagnoses accounted for most visits regardless of the number of recurrent visits. As the number of recurrent visits per patient rose, chronic diseases were increasingly represented, with asthma being the most common ED diagnosis. Trauma-related diagnoses were more common among patients without recurrent visits than among those with high-frequency recurrent visits (28% vs. 9%; p<0.001). High-frequency recurrent visits were more often within the highest severity score classifications. In multivariable analysis, recurrent visits were associated with younger age, black or Hispanic race or ethnicity, and public health insurance.

CONCLUSIONS

Risk factors for recurrent ED use by children include age, race and ethnicity, and insurance status. Although asthma plays an important role in recurrent ED use, acute illnesses account for the majority of recurrent ED visits.

Rationale, timeline, study design, and protocol overview of the therapeutic hypothermia after pediatric cardiac arrest trials

OBJECTIVE

To describe the rationale, timeline, study design, and protocol overview of the Therapeutic Hypothermia after Pediatric Cardiac Arrest trials.

DESIGN

Multicenter randomized controlled trials.

SETTING

Pediatric intensive care and cardiac ICUs in the United States and Canada.

PATIENTS

Children from 48 hours to 18 years old, who have return of circulation after cardiac arrest, who meet trial eligibility criteria, and whose guardians provide written consent.

INTERVENTIONS

Therapeutic hypothermia or therapeutic normothermia.

MEASUREMENTS AND MAIN RESULTS

From concept inception in 2002 until trial initiation in 2009, 7 years were required to plan and operationalize the Therapeutic Hypothermia after Pediatric Cardiac Arrest trials. Two National Institute of Child Health and Human Development clinical trial planning grants (R21 and R34) supported feasibility assessment and protocol development. Two clinical research networks, Pediatric Emergency Care Applied Research Network and Collaborative Pediatric Critical Care Research Network, provided infrastructure resources. Two National Heart Lung Blood Institute U01 awards provided funding to conduct separate trials of in-hospital and out-of-hospital cardiac arrest. A pilot vanguard phase that included half the clinical sites began on March 9, 2009, and this was followed by full trial funding through 2015.

CONCLUSIONS

Over a decade will have been required to plan, design, operationalize, and conduct the Therapeutic Hypothermia after Pediatric Cardiac Arrest trials. Details described in this report, such as participation of clinical research networks and clinical trial planning grants utilization, may be of utility for individuals who are planning investigator-initiated, federally supported clinical trials.

Social comparisons, health and well-being

Health and well-being are socially determined. One of the ways in which this comes about is via social comparisons with other individuals in the same personal, geographic or social networks, with the comparisons referring either to income or other aspects of economic and social life. The existence of such comparison effects with respect to income may help to explain the social gradient in health.

Early oxygenation and ventilation measurements after pediatric cardiac arrest: lack of association with outcome

OBJECTIVES

To explore oxygenation and ventilation status early after cardiac arrest in infants and children. We hypothesize that hyperoxia is common and associated with worse outcome after pediatric cardiac arrest.

DESIGN

Retrospective cohort study.

SETTING

Fifteen hospitals within the Pediatric Emergency Care Applied Research Network.

PATIENTS

Children who suffered a cardiac arrest event and survived for at least 6 hours after return of circulation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Analysis of 195 events revealed that abnormalities in oxygenation and ventilation are common during the initial 6 hours after pediatric cardiac arrest. Hyperoxia was frequent, affecting 54% of patients. Normoxia was documented in 34% and hypoxia in 22% of patients. These percentages account for a 10% overlap of patients who had both hyperoxia and hypoxia. Ventilation status was more evenly distributed with hyperventilation observed in 38%, normoventilation in 29%, and hypoventilation in 46%, with a 13% overlap of patients who had both hyperventilation and hypoventilation. Derangements in both oxygenation and ventilation were common early after cardiac arrest such that both normoxia and normocarbia were documented in only 25 patients (13%). Neither oxygenation nor ventilation status was associated with outcome. After controlling for potential confounders, arrest location and rhythm were significantly associated with worse outcome; however, hyperoxia was not (odds ratio for good outcome, 1.02 [0.46, 2.84]; p = 0.96).

CONCLUSIONS

Despite recent resuscitation guidelines that advocate maintenance of normoxia and normoventilation after pediatric cardiac arrest, this is uncommonly achieved in practice. Although we did not demonstrate an association between hyperoxia and worse outcome, the small proportion of patients kept within normal ranges limited our power. Preclinical data suggesting potential harm with hyperoxia remain compelling, and further investigation, including prospective, large studies involving robust recording of physiological derangements, is necessary to further advance our understanding of this important topic.

Surface degradation of dental ceramics as a function of environmental pH

We tested the hypotheses that glass-ceramic veneers and overglazes degrade by ion exchange in an acidic environment, and that they degrade by breakdown of the silica network in a basic environment. Disk specimens of glass-ceramic veneer and glaze were fabricated and immersed in pH 2, 7, or 10 buffer solutions, for 1, 3, 5, 10, 15, and 30 days. Each specimen was placed in a shaker bath containing de-ionized distilled water at 80°C. Concentrations of Al(3+), Ca(2+), Zn(2+), Li(2+), and Si(4+) were analyzed by means of inductively coupled plasma atomic emission spectrometry (ICP/AES). Statistical analyses were performed by factorial ANOVA. Significant differences occurred among leached ion concentrations as a function of material type, solution pH, and exposure time. A substantial release of Si occurred at pH 10 over time, leading to a breakdown of the glass phase. At pH 2, dissolution was controlled by an ionic exchange mechanism. We conclude that ceramic veneers and glazes may be susceptible to considerable degradation in low- and high-pH buffer solutions.

Fatal and near-fatal asthma in children: the critical care perspective

OBJECTIVE

To characterize the clinical course, therapies, and outcomes of children with fatal and near-fatal asthma admitted to pediatric intensive care units (PICUs).

STUDY DESIGN

This was a retrospective chart abstraction across the 8 tertiary care PICUs of the Collaborative Pediatric Critical Care Research Network (CPCCRN). Inclusion criteria were children (aged 1-18 years) admitted between 2005 and 2009 (inclusive) for asthma who received ventilation (near-fatal) or died (fatal). Data collected included medications, ventilator strategies, concomitant therapies, demographic information, and risk variables.

RESULTS

Of the 261 eligible children, 33 (13%) had no previous history of asthma, 218 (84%) survived with no known complications, and 32 (12%) had complications. Eleven (4%) died, 10 of whom had experienced cardiac arrest before admission. Patients intubated outside the PICU had a shorter duration of ventilation (median, 25 hours vs 84 hours; P < .001). African-Americans were disproportionately represented among the intubated children and had a shorter duration of intubation. Barotrauma occurred in 15 children (6%) before admission. Pharmacologic therapy was highly variable, with similar outcomes.

CONCLUSION

Of the children ventilated in the CPCCRN PICUs, 96% survived to hospital discharge. Most of the children who died experienced cardiac arrest before admission. Intubation outside the PICU was correlated with shorter duration of ventilation. Complications of barotrauma and neuromyopathy were uncommon. Practice patterns varied widely among the CPCCRN sites.

Comparing least-squares and quantile regression approaches to analyzing median hospital charges

BACKGROUND

Emergency department (ED) and hospital charges obtained from administrative data sets are useful descriptors of injury severity and the burden to EDs and the health care system. However, charges are typically positively skewed due to costly procedures, long hospital stays, and complicated or prolonged treatment for few patients. The median is not affected by extreme observations and is useful in describing and comparing distributions of hospital charges. A least-squares analysis employing a log transformation is one approach for estimating median hospital charges, corresponding confidence intervals (CIs), and differences between groups; however, this method requires certain distributional properties. An alternate method is quantile regression, which allows estimation and inference related to the median without making distributional assumptions.

OBJECTIVES

The objective was to compare the log-transformation least-squares method to the quantile regression approach for estimating median hospital charges, differences in median charges between groups, and associated CIs.

METHODS

The authors performed simulations using repeated sampling of observed statewide ED and hospital charges and charges randomly generated from a hypothetical lognormal distribution. The median and 95% CI and the multiplicative difference between the median charges of two groups were estimated using both least-squares and quantile regression methods. Performance of the two methods was evaluated.

RESULTS

In contrast to least squares, quantile regression produced estimates that were unbiased and had smaller mean square errors in simulations of observed ED and hospital charges. Both methods performed well in simulations of hypothetical charges that met least-squares method assumptions. When the data did not follow the assumed distribution, least-squares estimates were often biased, and the associated CIs had lower than expected coverage as sample size increased.

CONCLUSIONS

Quantile regression analyses of hospital charges provide unbiased estimates even when lognormal and equal variance assumptions are violated. These methods may be particularly useful in describing and analyzing hospital charges from administrative data sets.

Expanding CEP290 mutational spectrum in ciliopathies

Ciliopathies are an expanding group of rare conditions characterized by multiorgan involvement, that are caused by mutations in genes encoding for proteins of the primary cilium or its apparatus. Among these genes, CEP290 bears an intriguing allelic spectrum, being commonly mutated in Joubert syndrome and related disorders (JSRD), Meckel syndrome (MKS), Senior-Loken syndrome and isolated Leber congenital amaurosis (LCA). Although these conditions are recessively inherited, in a subset of patients only one CEP290 mutation could be detected. To assess whether genomic rearrangements involving the CEP290 gene could represent a possible mutational mechanism in these cases, exon dosage analysis on genomic DNA was performed in two groups of CEP290 heterozygous patients, including five JSRD/MKS cases and four LCA, respectively. In one JSRD patient, we identified a large heterozygous deletion encompassing CEP290 C-terminus that resulted in marked reduction of mRNA expression. No copy number alterations were identified in the remaining probands. The present work expands the CEP290 genotypic spectrum to include multiexon deletions. Although this mechanism does not appear to be frequent, screening for genomic rearrangements should be considered in patients in whom a single CEP290 mutated allele was identified.

Model studies of hydrogen atom addition and abstraction processes involving ortho-, meta-, and para-benzynes

H-atom addition and abstraction processes involving ortho-, meta-, and para-benzyne have been investigated by multiconfigurational self-consistent field methods. The H(A) + H(B)...H(C) reaction (where r(BC) is adjusted to mimic the appropriate singlet-triplet energy gap) is shown to effectively model H-atom addition to benzyne. The doublet multiconfiguration wave functions are shown to mix the "singlet" and "triplet" valence bond structures of H(B)...H(C) along the reaction coordinate; however, the extent of mixing is dependent on the singlet-triplet energy gap (DeltaE(ST)) of the H(B)...H(C) diradical. Early in the reaction, the ground-state wave function is essentially the "singlet" VB function, yet it gains significant "triplet" VB character along the reaction coordinate that allows H(A)-H(B) bond formation. Conversely, the wave function of the first excited state is predominantly the "triplet" VB configuration early in the reaction coordinate, but gains "singlet" VB character when the H-atom is close to a radical center. As a result, the potential energy surface (PES) for H-atom addition to triplet H(B)...H(C) diradical is repulsive! The H3 model predicts, in agreement with the actual calculations on benzyne, that the singlet diradical electrons are not coupled strongly enough to give rise to an activation barrier associated with C-H bond formation. Moreover, this model predicts that the PES for H-atom addition to triplet benzyne will be characterized by a repulsive curve early in the reaction coordinate, followed by a potential avoided crossing with the (pi)1(sigma*)1 state of the phenyl radical. In contrast to H-atom addition, large activation barriers characterize the abstraction process in both the singlet ground state and first triplet state. In the ground state, this barrier results from the weakly avoided crossing of the dominant VB configurations in the ground-state singlet (S0) and first excited singlet (S1) because of the large energy gap between S0 and S1 early in the reaction coordinate. Because the S1 state is best described as the combination of the triplet X-H bond and the triplet H(B)...H(C) spin couplings, the activation barrier along the S0 abstraction PES will have much less dependence on the DeltaE(ST) of H(B)...H(C) than previously speculated. For similar reasons, the T1 potential surface is quite comparable to the S0 PES.

Pulp capping with a modified bioglass formula (#A68-modified)

PURPOSE

To evaluate a modified Bioglass (Formula #68 (MBF68) when used as a pulp capping agent.

MATERIALS AND METHODS

After exposure, the pulps were contaminated with saliva for 60s, rinsed, dried and treated with Consepsis, acting as a hemostatic and bactericidal agent. After drying the Consepsis, the MFB68, having been pre-mixed in sterile saline, was carefully deposited over the pulp exposure, covered with polycarboxylate cement and restored with the ProBond bonding resin system. A calcium hydroxide group was used as control.

RESULTS

There was no evidence of mummification, the incidence of properly positioned dentin bridge formation was higher and the incidence of extruded dentin bridge formation was reduced.

A sol-gel derived bioactive fibrous mesh

Nonwoven sheets of bioactive fibers were produced using a sol-gel process. A high velocity spray process was used to prepare fibers of two compositions in the SiO(2)-CaO-P(2)O(5) ternary system. Both discontinuous fibers and dispersed fibers were evaluated. Viscosity and pH of the sol were the two primary processing variables studied. The formation of hydroxy carbonate apatite (HCA) on the surface of the fibers was used to evaluate the kinetics of the bioactivity in a simulated body fluid (SBF). Diffuse reflection infrared fourier transform spectroscopic (DRIFTS) analysis confirmed the presence of HCA (P-O). A homogenous layer of HCA, as observed with SEM (scanning electron microscopy), typically formed after 3-h immersion in the SBF. The concentration of HCA formed was greater for samples richer in silica. The new bioactive fiber sheets produced by this process are chemically more stable than powders or monoliths prepared from similar precursors. Potential applications are as scaffold for both mineralized and nonmineralized structural tissues.

Novel sol-gel bioactive fibers

Bioactive fibers were produced using a sol-gel method. The rheological properties of two different sol compositions prepared from a mixture of TEOS, phosphorous alkoxide and calcium nitrate, or calcium chloride in a water-ethanol solution, are reported. The sols were extruded through a spinneret to produce continuous 10 microm-diameter fibers. Discontinuous fibers and fibrous mats were prepared by air-spraying the multicomponent sols. The sol-gel fibers were converted to the bioactive fibers by three different thermal treatments at either 600 degrees, 700 degrees, or 900 degrees C for 3 h. SEM, BET, EDX, and FTIR were used to characterize the morphology and structure of the fibers. The BET measured surface area of the fibers sintered at 900 degrees C was 0 m(2)/gm compared to a value of 200 m(2)/gm for a typical sol-gel-derived particle of similar composition. Both the continuous and discontinuous fibers exhibited in vitro bioactivity in a simulated body fluid.

UDFT and MCSCF descriptions of the photochemical Bergman cyclization of enediynes

Several singlet and triplet potential energy surfaces (PES) for the Bergman cyclization of cis-1,5-hexadiyne-3-ene (1a) have been computed by UDFT, CI, CASCI, CASSCF, and CASMP2 methods. It is found that the first six excited states of 1a can be qualitatively described as linear combinations of the configurations of weakly interacting ethylene and acetylene units. Although the symmetry relaxation from C2nu to C2 makes cyclization of the 13B state Woodward-Hoffmann allowed, it also increases the probability of competing cis-trans isomerization. Hydrogen atom abstraction is another plausible pathway because the terminal alkyne carbons possess a large radical character. In view of the competing processes, we conclude that the Bergman cyclization along the 13B path is unlikely despite its exothermicity (Delta = -42 kcal/mol). Calculations on cyclic analogues of 1a lead to similar conclusions. A less exothermic, but more plausible pathway for photochemical cyclization lies on the 2(1)A PES (Delta = -18 kcal/mol). Compared to the 1(1)A(1) and 1(3)B states, the 2(1)A state has less in-plane electron repulsion which may facilitate cyclization. The resulting p-benzyne intermediate has an unusual electronic structure combining singlet carbene and open-shell diradical features. Deactivation of the 2(1)A state of 1a is a competing pathway.

Effectiveness of metal surface treatments in controlling microleakage of the acrylic resin-metal framework interface

STATEMENT OF PROBLEM

Microleakage at the junction between the metal alloy and acrylic resin in a removable partial denture may result in discoloration, fluid percolation, and acrylic resin deterioration. The junction between a metal alloy and acrylic resin is an area of clinical concern. Failure of a removable partial denture may be linked to this interface. Enhancing resistance to microleakage at this interface may improve the long-term union between the 2 materials.

PURPOSE

This investigation was designed to determine the effects of various metal surface treatment protocols on microleakage and bond strength between the metal alloy and acrylic resin used in the fabrication of a removable partial denture.

MATERIAL AND METHODS

Ninety-six nickel-chromium-beryllium alloy specimens were randomly divided into 8 groups. After adaptation of baseplate wax, each specimen was invested. Subsequent to wax removal, each specimen was divided into a control half and an experimental half. Air abrasion, tinplating/oxidation, and silanation were evaluated individually and in all combinations. Heat-polymerized acrylic resin was processed against all specimens before storage in distilled water at 37 degrees C for 72 hours. Each specimen then was thermocycled in distilled water (3000 cycles) before immersion in sodium fluorescein dye for 24 hours. Counting grids that exhibited dye penetration under ultraviolet light exposure allowed assessment of microleakage.

RESULTS

Air abrasion resulted in a significant decrease in microleakage when used individually and in all combinations (P<0.05). All experimental combinations that did not involve air abrasion demonstrated no significant reduction in measured microleakage between the experimental and control sides. Tukey's pair-wise comparison of the difference in the mean number of squares exhibiting microleakage between the control and treated sites for each experimental group revealed a significant difference, based on the involvement of air abrasion. Groups involving air abrasion did not differ significantly from each other (P<0.05). In addition, no significant difference was detected between groups not involving air abrasion (P<0.05).

CONCLUSION

Air abrasion, alone and in combination with tinplating/oxidation and with silanation, resulted in a significant reduction in microleakage between the metal alloy and acrylic resin.

Chronic insulin effects on insulin signalling and GLUT4 endocytosis are reversed by metformin

Decreases in insulin-responsive glucose transport and associated levels of cell surface GLUT4 occur in rat adipocytes maintained in culture for 20 h under hyperinsulinaemic and hyperglycaemic conditions. We have investigated whether this defect is due to reduced signalling from the insulin receptor, GLUT4 expression or impaired GLUT4 trafficking. The effects of chronic insulin treatment on glucose transport and GLUT4 trafficking were ameliorated by inclusion of metformin in the culture medium. In comparison with the ic insulin treatment attenuated changes in signalling processes leading to glucose transport. These included insulin receptor tyrosine phosphorylation, phosphoinositide 3-kinase activity and Akt activity, which were all reduced by 60-70%. Inclusion of metformin in the culture medium prevented the effects of the chronic insulin treatment on these signalling processes. In comparison with cells maintained in culture without insulin, the total expression of GLUT4 protein was not significantly altered by chronic insulin treatment, although the level of GLUT1 expression was increased. Trafficking rate constants for wortmannin-induced cell-surface loss of GLUT4 and GLUT1 were assessed by 2-N-4-(1-azi-2, 2,2-trifluoroethyl)benzoyl-1,3-bis(D-mannose-4-yloxy)-2-propyla min e (ATB-BMPA) photolabelling. In comparison with cells acutely treated with insulin, chronic insulin treatment resulted in a doubling of the rate constants for GLUT4 endocytosis. These results suggest that the GLUT4 endocytosis process is very sensitive to the perturbations in signalling that occur under hyperinsulinaemic and hyperglycaemic conditions, and that the resulting elevation of endocytosis accounts for the reduced levels of net GLUT4 translocation observed.

An investigation of bioactive glass powders by sol-gel processing

Bioactive glass powders, with a composition of SiO 2-CaO-P 2O 5, have been successfully synthesized via a sol-gel process at considerably lower temperatures than required for conventional melting methods. Bioactive glass powders made via conventional methods form an interfacial bond with bone when they are implanted. Bonding is correlated with the formation of a surface hydroxyapatite layer. This study examined the formation of a hydroxyapatite layer in Tris-buffered solution as a function of SiO 2 content of sol-gel derived powders. A FT-IRRS technique was used to monitor the formation of the hydroxyapatite on the surface of the powders. X-ray diffraction analysis and BET were also used to characterize the chemical and physical properties of the sol-gel derived bioactive powders. It was discovered that: (a) the rate of hydroxyapatite formation decreased with increasing SiO 2 content for powders whose SiO 2 content was less than 90 mol%; (b) a hydroxyapatite film does not form for the powders whose SiO 2 content is more than 90 mol%; (c) the SiO 2 limit, beyond which the powders lost their bioactivity, was much higher for bioactive glass powders made through sol-gel process (90%) than those made by conventional melting methods (60%). These results indicate that it is possible to significantly expand the bioactive composition range through microstructural control made possible by sol-gel processing techniques.

Dietary fiber differentially alters cellular fatty acid-binding protein expression in exfoliated colonocytes during tumor development

We investigated the utility of noninvasive technology utilizing feces containing exfoliated colonocytes to determine whether changes in fecal fatty acid-binding proteins have predictive value in monitoring the neoplastic process. Ninety male Sprague-Dawley rats were randomly divided into four groups in a 2 x 2 factorial design, with two dietary fiber sources (wheat bran or oat bran) and two treatment groups (injection with a carcinogen, azoxymethane, or saline). Fresh fecal samples were collected at Week 16 postinjection, and tumor frequency was determined at Week 36 of the study. Semiquantitative "mimic" reverse transcriptase polymerase chain reaction was used to quantitate the expression of liver fatty acid-binding protein (L-FABP), intestinal fatty acid-binding protein (i-FABP), and acyl CoA-binding protein (ACBP) mRNA in fecal samples to establish their prognostic value. Rats fed wheat bran diets had a lower incidence of tumors (p < 0.05). There was no effect of carcinogen injection or tumor incidence on the expression of L-FABP, i-FABP, or ACBP mRNA, L-FABP and i-FABP mRNA expression were significantly higher (p < 0.05) in feces from animals fed a wheat bran diet than in feces from animals fed an oat bran diet. In contrast, the expression of ACBP mRNA was significantly lower (p < 0.05) in animals fed a wheat bran diet than in animals fed an oat bran diet. Wheat bran also increased (p < 0.05) the total excretion of L-FABP, i-FABP, and ACBP over a 48-hour period. These data suggest that exfoliated colonocyte fatty acid-binding protein mRNA status may provide insight into the mechanisms by which diet influences colonic physiology.

Cyclic anhydride ring opening reactions: theory and application

The development of a zero net shrinkage dental restorative material based upon a polymer-bioactive-glass composite requires a second-phase material that expands. This study details the mechanisms of organic cyclic anhydride ring expansion via hydrolysis. Six cyclic anhydrides were used to represent potential side groups, each of which could be an expanding phase or component. Maleic, 4META, tetrahydrophthalic, norbornene, itaconic, and succinic anhydrides were modeled using the Austin method (AM1), a semi-empirical molecular orbital method. The reaction pathways were determined for the anhydride ring opening reaction to form an acid for each case. The activation barriers (Ea) for the ring openings were found from the transition state geometries wherein only one imaginary eigen value in the vibration spectrum existed (a true saddle point). In each case the reaction pathway included the hydrogen bonding of a H2O molecule to the ring, weakening of the C-O bridging bonds of the ring, and, finally, the dissociation of the H2O, forming two carboxyl groups and opening the ring. The activation for the ring openings are +34.3, +36.9, +40.6, +43.1, +45.9, and +47.7 kcal/mol, respectively. The volumetric expansion of the anhydrides was estimated based upon the dilation of C-O-C atomic distances. The dimensional change was found to be 24.0%, 24.0%, 19.1%, 20.3%, 20.8%, and 17.9% for the anhydride rings, respectively. Finally, it was found that a linear correlation exists between the cyclic anhydride C-O asymmetric rocking (as-v) vibration and the activation energy (Ea) for hydrolysis to an acid. This may be used as an experimental indicator of a cyclic anhydride's activity.

Effect of insulin on GLUT4 cell surface content and turnover rate in human skeletal muscle as measured by the exofacial bis-mannose photolabeling technique

Insulin-stimulated glucose transport across the skeletal muscle cell membrane is a major regulatory step in postprandial glucose disposal. To estimate the total molar concentration of GLUT4 as well as the turnover rate of GLUT4 in human vastus lateralis muscles at the cell surface in the basal state and after insulin exposure, we have applied the sensitive exofacial bis-mannose photolabeling technique on in vitro incubated human skeletal muscle strips from healthy subjects. In addition, we have measured 3-O-methylglucose transport in other muscle strips prepared from the same surgically removed human skeletal muscle biopsies to compare glucose transport with cell surface level of GLUT4. Maximal in vitro insulin stimulation (2,400 pmol/l) resulted in a twofold increase compared with basal in both surface GLUT4 content (0.38 +/- 0.05 vs. 0.19 +/- 0.03 pmol/g wet muscle wt, P < 0.005) and 3-O-methylglucose transport (1.24 +/- 0.13 vs. 0.63 +/- 0.08 pmol x ml(-1) x h(-1), P < 0.005). The insulin-induced increment in 3-O-methylglucose transport was strongly correlated with the insulin-induced increase in cell surface GLUT4 content (r2 = 0.91; P < 0.005). The calculated turnover rate of human skeletal muscle GLUT4 amounted to approximately 8 x 10(4) min(-1) at 35 degrees C and was unaffected by insulin. In conclusion, maximal in vitro insulin stimulation of vastus lateralis muscle strips from healthy subjects resulted in a twofold rise in glucose transport as well as in cell surface content, whereas the turnover rate of GLUT4 was unaffected by insulin under the chosen experimental conditions.

Molecular orbital models of ring expansion mechanisms in the silica-carbon monoxide system

The development of a zero net shrinkage dental restorative material based upon a polymer-bioactive glass composite requires a second-phase material that expands. This study details the mechanisms of silica ring expansion by reaction with carbon monoxide. Carbon monoxide was used as a model adduct to represent potentially active sites on the polymer phase of the dental restorative. Silica rings were used to model the bioactive-glass phase of the composite. The 3-, 4-, 5-, and 6-"member" silica rings have been modeled using the Austin Method (AM1) semi-empirical molecular orbital calculations. The reaction pathways were determined for carbon monoxide (CO) reaction addition to each of the rings. The activation barriers (Ea) for the ring expansions were determined from the transition state geometries wherein only one imaginary eigenvalue in the vibration spectrum existed (a true saddle point). In each case the reaction pathway included the hydrogen bonding of CO with a silicon, exothermic pentacoordinate bonding to silicon by the CO and weakening of the Si-O bridging bonds of the ring, and, finally, the incorporation of CO into the ring, forming a silica-carbonate ring. The activation for the ring expansions are +4.3, +6.1, +7.0, and -2.9 Kcal/mol for 3-, 4-, 5-, and 6-"member" silica rings, respectively. The volumetric expansion of the silica was estimated based upon the dilation of adjacent silicon-silicon atomic distances. The dimensional change was calculated to be 3.9%, 21.3%, 19.4%, and 24.2% for 3-, 4-, 5-, and 6-membered silica-carbonate rings, respectively.

Clinical use of a bioactive glass particulate in the treatment of human osseous defects

The dental practitioner has a wide choice of materials available for use in bone grafting procedures. A bioactive glass particulate possesses many favorable qualities not often found in other materials, including the ability to remain where placed even with adjacent suctioning; hemostasis; and incorporation into the host bone without the fibrous encapsulation encountered with most other synthetic materials. It is also quick and easy to prepare. This article reviews clinical experiences with PerioGlas in the setting of private practice periodontics, in which this material was used as the grafting material for periodontal defects, apicoectomies, cysts, and ridge augmentation and maintenance procedures, as well as for implant repairs. Several cases detail the advantages of this grafting material.

Using 45S5 bioglass cones as endosseous ridge maintenance implants to prevent alveolar ridge resorption: a 5-year evaluation

Bioglass cones acting as space fillers after removal of tooth roots delay the resorption of alveolar ridges. In 1987, 242 implants in 29 patients with a mean postimplantation interval of 19.9 months were reported by the authors. Bioglass cones had been fitted snugly at least 2 mm below the alveolar crest, and dentures were placed no sooner than 6 weeks following tooth removal; 2.9% had been lost and 3.7% developed dehiscences. The present report on 168 implants in 20 recalled patients (mean postimplantation interval of 63.2 months) revealed a loss of 14.3% of the implants and 7.7% of the implants requiring recontouring. Literature indicates highest survival rates for implants in the anterior mandible; however, the present data demonstrate a statistically significant retention rate in the anterior maxilla. With this high rate of Bioglass cone retention (85.7%) after 5 years, their placement into fresh sockets to maintain the alveolar ridge is recommended.

Identification of SNAP receptors in rat adipose cell membrane fractions and in SNARE complexes co-immunoprecipitated with epitope-tagged N-ethylmaleimide-sensitive fusion protein

The vesicle-associated membrane proteins [VAMPs; vesicle SNAP receptors (v-SNAREs)] present on GLUT4-enriched vesicles prepared from rat adipose cells [Cain, Trimble and Lienhard (1992) J. Biol. Chem. 267, 11681-11684] have been identified as synaptobrevin 2 (VAMP 2) and cellubrevin (VAMP 3) by using isoform-specific antisera. Additional antisera identify syntaxins 2 and 4 as the predominant target membrane SNAP receptors (t-SNAREs) in the plasma membranes (PM), with syntaxin 3 at one-twentieth the level. Syntaxins 2 and 4 are enriched 5-10-fold in PM compared with low-density microsomes (LDM). Insulin treatment results in an 11-fold increase in immunodetectable GLUT4 in PM and smaller (approx. 2-fold) increases in VAMP 2 and VAMP 3, whereas the subcellular distributions of the syntaxins are not altered by insulin treatment. To determine which of the SNAP receptors (SNAREs) in PM might participate in SNARE complexes with proteins from GLUT4 vesicles, complexes were immunoprecipitated with anti-myc antibody from solubilized membranes after the addition of myc-epitope-tagged N-ethylmaleimide-sensitive fusion protein (NSF) and recombinant alpha-soluble NSF attachment protein (alpha-SNAP). These complexes contain VAMPs 2 and 3 and syntaxin 4, but not syntaxins 2 or 3. Complex formation requires ATP and is disrupted by ATP hydrolysis. When all membrane fractions are prepared from basal cells, few or no VAMPs and no syntaxin 4 are immunoprecipitated in SNARE complexes obtained from LDM alone (or from immunoisolated GLUT4 vesicles). The content of syntaxin 4 depends on the presence of PM, and participation of VAMPs 2 and 3 is enhanced 4-6-fold by the addition of solubilized GLUT4 vesicles to PM. The latter increase is greater than can be explained by the 2-fold higher levels of VAMPs added to the reaction mixture. When all membrane fractions are prepared from insulin-stimulated cells, SNARE complexes formed from PM alone contain similar levels of syntaxin 4 but 5-6-fold higher levels of VAMPs 2 and 3 compared with PM alone from basal cells. Addition of GLUT4 vesicle proteins to PM from insulin-treated cells results in a further 2-fold increase in VAMP 2 recovered in SNARE complexes. Therefore the VAMPs in PM of insulin-treated but not basal cells, and in GLUT4-vesicles from cells in either condition, are in a form that readily forms a SNARE complex with PM t-SNAREs and NSF. Insulin seems to activate PM and/or GLUT4 vesicles so as to increase the efficiency of SNARE complex formation.

Autonomy and death

In this Article, Professor Clark explores the contours of the current debate over physician-assisted death. She beings by focusing on the legal issues raised by statutory attempts to either legalize or criminalize physician-assisted death, with particular emphasis on the constitutional questions that are currently before the United States Supreme Court. She then examines physician-assisted death from both medical and societal perspectives. Professor Clark uses a thought experiment in which assisted death is facilitated by persons other than physicians, and in doing so, questions whether physicians are the proper persons in whom to rest power over assisted death. She points out the irony in a process that would set up physicians as protectors of individual autonomy, and ultimately concludes that by deferring to the medical profession in this process, we risk losing the very autonomy that assisted death is designed to effectuate.

Decreased tyrosine transport in fibroblasts from schizophrenics: implications for membrane pathology

Two independent studies reported recently have shown a significant decrease in Vmax of tyrosine transport in fibroblasts grown from schizophrenics' skin compared with controls. It has also been shown that tyrosine transport into the brain is decreased in schizophrenics compared with controls. In view of the importance of these findings in elucidating the biochemical mechanism(s) associated with schizophrenia, we have studied the kinetics of tyrosine transport and the levels of monoamine oxidase (MAO) activity in fibroblasts grown from the skins of schizophrenics and unrelated control subjects. Using the Lineweaver-Burk plot, the Eadie Hostee plot and the Hanes plot we have calculated the Km and Vmax for tyrosine transport. We have found a significant decrease in the Km and Vmax values for tyrosine transport in schizophrenics compared with control fibroblast samples. No changes were observed in the levels of MAO. Using Lineweaver-Burk plot (1/S Versus 1/V) it has been shown that the tyrosine transport inhibition is uncompetitive. This finding proposes that the inhibition is in the substrate transport protein complex, which may be taking place during the transit of the substrate through the cell membrane. From the observed findings and from the literature evidence we suggest that the altered metabolism of phospholipids in schizophrenics, such as deficiency of arachidonic acid and docosahexaenoic acid, may be contributing to this observed phenomena.

A study of enzymes involved in catecholamine metabolism in parents of patients with schizophrenia

The concentrations of serum homovanillic acid (HVA), norepinephrine (NE), tyrosine (Tyr), phenylalanine (Phe) and tryptophan (Trp), and the activities of serum dopamine-beta-hydroxylase (DBH), platelet monoamine oxidase (MAO), and erythrocyte catechol-O-methyl transferase (COMT) were measured in 68 healthy parents who had schizophrenic offspring. The results show a significant correlation between the parents of schizophrenic patients in serum HVA (r=0.38, n=34, p<0.05), NE (r=0.40, n=33, p<0.02), Phe (r=0.44, n=34, p<0.0l), Tyr (r=0.43, n = 34, p <0.02) and DBH activity (r=0.51, n = 30, p <0.005), but do not show a significant correlation in erythrocyte COMT (r=0.01, n=27), platelet MAO (r=0.04, n=23) or serum Trp (r=0.10, n=34). There were no significant correlations in these measurements between randomly matched parents. The present study suggests that both parental sides of schizophrenic patients are likely to have similar alleles associated with the catecholamine pathway, and their ill offspring may possess a double dose of the schizophrenogenic alleles.

Analysis of the structural features of the C-terminus of GLUT1 that are required for transport catalytic activity

C-terminally truncated and mutated forms of GLUT1 have been constructed to determine the minimum structure at the C-terminus required for glucose transport activity and ligand binding at the outer and inner binding sites. Four truncated mutants have been constructed (CTD24 to CTD27) in which 24 to 27 amino acids are deleted. In addition, point substitutions of R468-->L, F467-->L and G466-->E have been produced. Chinese hamster ovary clones which were transfected with these mutant GLUT1s were shown, by Western blotting and cell-surface carbohydrate labelling, to have expression levels which were comparable with the wild-type clone. Wild-type levels of 2-deoxy-D-glucose transport activity were retained only in the clone transfected with the construct in which 24 amino acids were deleted (CTD24). The CTD25, CTD26 and CTD27 clones showed markedly reduced transport activity. From a kinetic comparison of the CTD24 and CTD26 clones it was found that the reduced transport was mainly associated with a reduced Vmax. value for 2-deoxy-D-glucose uptake but with a slight lowering of the Km. These data establish that the 24 amino acids at the C-terminus of GLUT1 are not required for the transport catalysis. However, the point mutations of F467L and G466E (26 and 27 residues from the C-terminus) did not significantly perturb the kinetics of 2-deoxy-D-glucose transport. The substitution of R468L produced a slight, but significant, lowering of the Km. The ability of the truncated GLUt1s to bind the exofacial ligand, 2-N-4-(1-zai-2,2,2-trifluoroethyl)benzoyl-1,3-bis-(D-mannos- 4-yl-oxy) -2-propylamine (ATB-BMPA), and the endofacial ligand, cytochalasin B, were assessed by photolabelling procedures. The ability to bind ATB-BMPA was retained only in the CTD24 truncated mutant and was reduced to levels comparable with those of the non-transfected clone in the other mutant clones. Cytochalasin B labelling was unimpaired in all four mutated GLUT1s. These data establish that a minimum structure at the C-terminus of GLUT1, which is required for the conformational change to expose the exofacial site, includes amino acids at positions Phe-467 and Arg-468; however, these amino acids are not individually essential.