bluuebunny/crossref_metadata_2025 huggingface dataset:
Are We There Yet? Distance to Care and Relative Supply Among Pediatric Medical Subspecialties
Authors: Mayer Michelle L.
Published: December 2006

OBJECTIVE. The objective of this study was to describe geographic proximity, quantify variation in supply, and estimate pediatric population increments that are needed to support providers across pediatric subspecialties.

METHODS. Data from the American Board of Pediatrics and the Claritas Pop-Facts Database were used to calculate subspecialty-specific straight-line distances between each zip code and the nearest board-certified subspecialist. These data sources also were used to estimate the percentage of hospital referral regions with providers and calculate physician-to-population ratios for each of 16 pediatric medical subspecialties. Coefficients of variation for the ratios were used to assess intraspecialty variation in supply across markets. Estimates of the pediatric population that is needed to support an initial or additional physician in a market were generated using subspecialty-specific ordered logit analyses.

RESULTS. The population-weighted average distance to a subspecialist ranged from 15 miles for neonatology to 78 miles for pediatric sports medicine. For most pediatric subspecialties, more than two thirds of children live within 40 miles of a certified physician. For 7 of 16 of pediatric subspecialties, fewer than one half of hospital referral regions have a provider. Coefficients of variation vary across subspecialties and are lowest for neonatology at 76% and greatest for pediatric sports medicine at 287%. Pediatric population thresholds likewise vary with a tendency toward lower thresholds for procedural specialties, such as cardiology and critical care medicine.

CONCLUSIONS. The practice locations of pediatric subspecialists parallel the geographic distribution of children in the United States, yet many hospital referral regions lack pediatric subspecialists and coefficients of variation vary widely across subspecialties. These findings suggest that either the supply of pediatric subspecialists is inadequate, pediatric subspecialists are distributed inequitably, or the market for pediatric subspecialists is larger than the hospital referral regions. Furthermore, population thresholds for many cognitive pediatric subspecialties are high; the extent to which high thresholds reflect low disease prevalence versus other factors, such as inadequate reimbursement, is not established.
Patterns of Inhaled Antiinflammatory Medication Use in Young Underserved Children With Asthma
Authors: Butz Arlene M. , Tsoukleris Mona , Donithan Michele , Hsu Van Doren , Mudd Kim , Zuckerman Ilene H. , Bollinger Mary E.
Published: December 2006

BACKGROUND. Asthma guidelines advocate inhaled corticosteroids as the cornerstone treatment of persistent asthma, yet several studies report underuse of inhaled corticosteroids in children with persistent asthma. Moreover, few studies use objective pharmacy data as a measure of drug availability of asthma medications. We examined factors associated with the use of inhaled corticosteroids in young underserved children with persistent asthma using pharmacy records as their source of asthma medications.

METHODS. This was a cross-sectional analysis of questionnaire and pharmacy record data over a 12-month period from participants enrolled in a randomized clinical trial of a nebulizer educational intervention.

RESULTS. Although exposure to ≥1 inhaled corticosteroids refill was high at 72%, 1 of 5 children with persistent asthma had either no medication or only short-acting β agonist fills for 12 months. Only 20% of children obtained ≥6 inhaled corticosteroids fills over 12 months. Obtaining ≥3 inhaled corticosteroids fills over 12 months was significantly associated with an increase in short-acting β agonist fills and receiving specialty care in the regression models while controlling for child age, asthma severity, number of emergency department visits, having an asthma action plan, and seeking preventive care for the child's asthma.

CONCLUSIONS. Overreliance on short-acting β agonist and underuse of inhaled corticosteroid medications was common in this group of young children with persistent asthma. Only one fifth of children obtained sufficient controller medication fills.
3-Methylcrotonyl-CoA Carboxylase Deficiency: Metabolic Decompensation in a Noncompliant Child Detected Through Newborn Screening
Authors: Ficicioglu Can , Payan Irma
Published: December 2006

We report a 19-month-old girl with a 3-methylcrotonyl-coenzyme A carboxylase deficiency that was detected through newborn screening. She was treated for the first 12 months but was lost to follow-up after the initial year. Her parents did not comply with the recommendations for management during periods of illness or for regular medical evaluations. During an acute illness, she presented with severe acidosis, hypoglycemia, and a low plasma carnitine level at 19 months of age. This report highlights the importance of more extensive follow-up plans to improve parental compliance.
Higher Survival Rates Among Younger Patients After Pediatric Intensive Care Unit Cardiac Arrests
Authors: Meaney Peter A. , Nadkarni Vinay M. , Cook E. Francis , Testa Marcia , Helfaer Mark , Kaye William , Larkin G. Luke , Berg Robert A. ,   for the American Heart Association National Registry of Cardiopulmonary Resuscitation Investigators
Published: December 2006

BACKGROUND. Age is an important determinant of outcome from adult cardiac arrests but has not been identified previously as an important factor in pediatric cardiac arrests except among premature infants. Chest compressions can result in more effective blood flow during cardiac arrest in an infant than an older child or adult because of increased chest wall compliance. We, therefore, hypothesized that survival from cardiac arrest would be better among infants than older children.

METHODS. We evaluated 464 pediatric ICU arrests from the National Registry of Cardiopulmonary Resuscitation from 2000 to 2002. NICU cardiac arrests were excluded. Data from each arrest include >200 variables describing facility, patient, prearrest, arrest intervention, outcome, and quality improvement data. Age was categorized as newborn (<1 month; N = 62), infant (1 month to <1 year; N = 105), younger child (1 year to <8 years; N = 90), and older child (8 years to <21 years; N = 207). Multivariable logistic regression was performed to examine the association between age and survival.

RESULTS. Overall survival was 22%, with 27% of newborns, 36% of infants, 19% of younger children and 16% of older children surviving to hospital discharge. Newborns and infants demonstrated double and triple the odds of surviving to hospital discharge from a cardiac arrest in an intensive care setting when compared with older children. When potential confounders were controlled, newborns increased their advantage to almost fivefold, while infants maintained their survival advantage to older children.

CONCLUSIONS. Survival from pediatric ICU cardiac arrest is age dependent. Newborns and infants have better survival rates even after adjusting for potential confounding variables.
Acute Brain Herniation From Lead Toxicity
Authors: Berkowitz Sheldon , Tarrago Rod
Published: December 2006

A 4-year-old black boy was admitted to the hospital with vomiting, low-grade fever, and dehydration that were thought to be caused by viral gastroenteritis. He proceeded over the next 12 hours to rapidly deteriorate with brain herniation leading to brain death. The ultimate cause of death was found to be acute lead intoxication from a swallowed foreign body.
To What Extent Is the Protective Effect of Breastfeeding on Future Overweight Explained by Decreased Maternal Feeding Restriction?
Authors: Taveras Elsie M. , Rifas-Shiman Sheryl L. , Scanlon Kelley S. , Grummer-Strawn Laurence M. , Sherry Bettylou , Gillman Matthew W.
Published: December 2006

OBJECTIVE. Previous studies have found that breastfeeding may protect infants against future overweight. One proposed mechanism is that breastfeeding, as opposed to bottle feeding, promotes maternal feeding styles that are less controlling and more responsive to infant cues of hunger and satiety, thereby allowing infants greater self-regulation of energy intake. The objective of this study was to determine the extent to which the protective effect of breastfeeding on future overweight is explained by decreased maternal feeding restriction.

PATIENTS AND METHODS. We studied 1012 mother-infant pairs in Project Viva, an ongoing prospective cohort study of pregnant mothers and their children. The main exposure was breastfeeding duration, assessed at 1 year postpartum. At 3 years of age, the main outcomes were age- and gender-specific BMI z score and the sum of subscapular and triceps skinfold thicknesses, with overweight defined as a BMI ≥95th percentile. We defined maternal restriction of infant’s access to food as strongly agreeing or agreeing, with the following question from the Child Feeding Questionnaire: “I have to be careful not to feed my child too much.” To examine the association between breastfeeding duration and our outcomes, we used multivariate linear and logistic models, adjusting for several potential confounders. In subsequent models, we also adjusted for maternal restriction of infant’s access to food.

RESULTS. The mean duration of breastfeeding was 6.5 months, and 12% of women strongly agreed or agreed with the restriction question. At age 3, mean for BMI z score was 0.47. Each 3-month increment in breastfeeding duration was associated with a reduction of 0.045 BMI z score. After adjusting for maternal restriction, the estimate was −0.039, a 13% attenuation.

CONCLUSION. The protective effect of breastfeeding on future overweight seems to be explained only partially by decreased maternal feeding restriction.
A Fast Procedure for the Detection of Defects in Toll-like Receptor Signaling
Authors: von Bernuth Horst , Ku Cheng-Lung , Rodriguez-Gallego Carlos , Zhang Shenying , Garty Ben-Zion , Maródi László , Chapel Helen , Chrabieh Maya , Miller Richard L. , Picard Capucine , Puel Anne , Casanova Jean-Laurent
Published: December 2006

OBJECTIVES. Inborn defects in Toll-like receptor signaling are recently described primary immunodeficiencies that predispose affected children to life-threatening infections. Patients with interleukin-1 receptor-associated kinase-4 deficiency are prone to invasive pneumococcal disease, and patients with UNC-93B deficiency are prone to herpes simplex virus encephalitis. These genetic disorders are underdiagnosed, partly because diagnosis currently requires expensive and time-consuming techniques available at only a few specialized centers worldwide. We, therefore, aimed to develop a cheap and fast test for the detection of defects in Toll-like receptor signaling.

PATIENTS AND METHODS. We used flow cytometry to evaluate the cleavage of membrane-bound L-selectin on granulocytes in 38 healthy controls and in 7 patients with genetically defined Toll-like receptor signaling defects (5 patients with interleukin-1 receptor-associated kinase-4 deficiency and 2 patients with UNC-93B deficiency), on activation with various Toll-like receptor agonists.

RESULTS. Impaired L-selectin shedding was observed with granulocytes from all of the interleukin-1 receptor-associated kinase-4-deficient patients on activation with agonists of Toll-like receptors 1/2, 2/6, 4, 7, and 8 and with granulocytes from all of the UNC-93B-deficient patients on activation with agonists of Toll-like receptors 7 and 8. All of the healthy controls responded to these stimuli.

CONCLUSIONS. The assessment of membrane-bound L-selectin cleavage on granulocytes by flow cytometry may prove useful for the detection of primary immunodeficiencies in the Toll-like receptor pathway, such as interleukin-1 receptor-associated kinase-4 deficiency and UNC-93B deficiency. This procedure is cheap and rapid. It may, therefore, be suitable for routine testing worldwide in children with invasive pneumococcal disease and in patients with herpes simplex encephalitis.
Asthma as a Barrier to Children's Physical Activity: Implications for Body Mass Index and Mental Health
Authors: Glazebrook Cristine , McPherson Amy C. , Macdonald Ian A. , Swift Judy A. , Ramsay Christopher , Newbould Rachel , Smyth Alan
Published: December 2006

OBJECTIVES. The purpose of this work was to identify barriers to physical activity in children with asthma and to compare their customary activity levels, BMI and emotional well-being with that of children with other medical conditions. It was hypothesized that children with asthma would have higher BMI and lower levels of customary activity.

PATIENTS AND METHODS. We studied children aged 7 to 14 years attending hospital outpatient clinics for either asthma (asthma group: n = 56) or for otorhinolaryngology or dermatological conditions (nonasthma group: n = 61). In this cross-sectional survey, children's weight and height were recorded and their BMI classified according to International Obesity Task Force classification of obesity. Child mental health was assessed by the parent-rated Strengths and Difficulties Questionnaire. The child-rated Physical Activity Questionnaire assessed total sedentary and physical activities during the previous 24 hours.

RESULTS. The asthma group had a higher mean BMI (20.78 vs 18.82) and higher rates of obesity (21.4% vs 6.6%). Children with asthma reported fewer physical activities than the nonasthma group (median 4 per day vs 6 per day) but comparable levels of sedentary activities. Asthma was the strongest predictor of lower activity scores, followed by younger age. The asthma group had higher levels of emotional difficulties and, within this group, more active children had better mental health. More parents in the asthma group identified the child's health as a barrier to exercise (60.7% vs 11%). The same was true of children (66.1% vs 11.5%).

CONCLUSIONS. We found that children attending a hospital clinic for asthma were more likely to be obese and were significantly less active than a comparison group with other medical conditions. Asthma was identified as a barrier to exercise by parents and children. Strategies to promote exercise within pediatric asthma care are needed to protect both mental and physical health.
A National Survey of Pediatrician Knowledge and Attitudes Regarding Human Papillomavirus Vaccination
Authors: Daley Matthew F. , Liddon Nicole , Crane Lori A. , Beaty Brenda L. , Barrow Jennifer , Babbel Christine , Markowitz Lauri E. , Dunne Eileen F. , Stokley Shannon , Dickinson L. Miriam , Berman Stephen , Kempe Allison
Published: December 2006

OBJECTIVE. A human papillomavirus vaccine was licensed in June 2006. The vaccine is quadrivalent, protecting against 2 human papillomavirus strains that cause cervical cancer and 2 that cause genital warts. The objective of this study was to determine physician characteristics, knowledge, and attitudes associated with an intention to recommend human papillomavirus vaccination.

METHODS. Between August and October 2005, a cross-sectional survey was administered to a national network of 431 pediatricians. The network was developed from a random sample of American Academy of Pediatrics members and was designed to be representative of the organization’s membership with respect to urban/rural location, practice type, and region. The survey was conducted before human papillomavirus vaccine licensure and therefore focused on a candidate quadrivalent human papillomavirus vaccine and a range of potential vaccination recommendations. The main outcome measure was intention to recommend a quadrivalent human papillomavirus vaccine to young adolescent (10- to 12-year-old) females.

RESULTS. Survey response rate was 68%. If endorsed by national health organizations, 46% of respondents would recommend vaccination for 10- to 12-year-old females, 77% for 13- to 15-year-old females, and 89% for 16- to 18-year-old females. Corresponding rates for males were 37%, 67%, and 82%, respectively. Whereas 60% of respondents thought that parents would be concerned that human papillomavirus vaccination may encourage risky sexual behaviors, 11% reported that they themselves had this concern. Respondents who believed that other new adolescent immunization recommendations (eg, meningococcal, pertussis) would facilitate human papillomavirus vaccine implementation were more likely to intend to recommend vaccination.

CONCLUSIONS. Although a national sample of pediatricians expressed a high level of acceptance of human papillomavirus vaccination in older adolescent females, fewer than one half anticipated giving human papillomavirus vaccine to younger female patients. Provider concerns about parental vaccine acceptance will need to be addressed to optimize human papillomavirus vaccination implementation.
Preventable Newborn Readmissions Since Passage of the Newborns’ and Mothers’ Health Protection Act
Authors: Paul Ian M. , Lehman Erik B. , Hollenbeak Christopher S. , Maisels M. Jeffrey
Published: December 2006

BACKGROUND. Congress passed the Newborns’ and Mothers’ Health Protection Act in 1996, reversing the trend of shorter newborn nursery lengths of stay. Hope existed that morbidities would lessen for this vulnerable population, but some reports indicate that the timeliness and quality of postdischarge care may have worsened in recent years.

OBJECTIVE. Our goal was to determine risk factors for the potentially preventable readmissions because of jaundice, dehydration, or feeding difficulties in the first 10 days of life in Pennsylvania since passage of the Newborns’ and Mothers’ Health Protection Act.

PATIENTS AND METHODS. Birth records from 407826 newborns ≥35 weeks’ gestation from 1998 to 2002 were merged with clinical discharge records. A total of 2540 newborns rehospitalized for jaundice, dehydration, or feeding difficulties in the first 10 days of life were then compared with 5080 control infants. Predictors of readmission were identified by using multiple logistic regression analysis.

RESULTS. An unadjusted comparison of baseline characteristics revealed numerous predictors of readmission. Subsequent adjusted analysis revealed that Asian mothers, those 30 years of age or older, nonsmokers, and first-time mothers were more likely to have a readmitted newborn, as were those with diabetes and pregnancy-induced hypertension. For neonates, female gender and delivery via cesarean section were protective for readmission, whereas vacuum-assisted delivery, gestational age <37 weeks, and nursery length of stay <72 hours were predictors of readmission in the first 10 days of life.

CONCLUSIONS. Although readmissions for jaundice, dehydration, and feeding difficulties may be less common for some minority groups and Medicaid recipients in the era of the Newborns’ and Mothers’ Health Protection Act compared with nonminorities or privately insured patients, several predictors of newborn readmission have established associations with inexperienced parenting and/or breastfeeding difficulty. This is one indication that this well-intentioned legislation and current practice may not be sufficiently protecting the health of newborns and suggests that additional support for mothers and newborns during the vulnerable postdelivery period may be indicated.
Do Antireflux Operations Decrease the Rate of Reflux-Related Hospitalizations in Children?
Authors: Goldin Adam B. , Sawin Robert , Seidel Kristy D. , Flum David R.
Published: December 2006

OBJECTIVE. Gastroesophageal reflux disease is extremely common in the pediatric population, and antireflux procedures are performed with increasing frequency. The objective of this study was to determine whether pediatric antireflux procedures are associated with a decreased rate of reflux-related hospitalizations.

METHODS. A study was conducted of pediatric patients who were undergoing antireflux procedures using data that were derived from the Washington State Comprehensive Hospital Abstract Reporting System and Vital Records. Patients were identified by a search of all records (1987–2001) for procedure codes that pertained to antireflux procedures in patients who were younger than 19 years. The number of hospitalizations for and rates of reflux-related events per patient-year before and after an antireflux procedure was calculated, and factors that were associated with higher antireflux procedure rates were examined.

RESULTS. A total of 1142 patients underwent antireflux procedures. The rate of reflux-related events declined sharply with age both before and after an antireflux procedure. The cohort was divided into 3 groups on the basis of age at first antireflux procedure (<1 year, 1–3 years, or 4–19 years), and the calculations of incidence rate ratios before to after an antireflux procedure were done within the same age strata. Results suggest an overall benefit of antireflux procedures in young children. For antireflux procedures that were performed in children who were older than 4 years, the benefit is less clear. Developmental delay was significantly associated with higher rates of reflux-related events among patients who underwent an antireflux procedure after age 4.

CONCLUSIONS. The rate of reflux-related events was lower after an antireflux operation for children who underwent an antireflux procedure before age 4. Older children, however, were hospitalized at equal rates before and after an antireflux procedure, and older children with developmental delay were hospitalized at greater rates after an antireflux procedure. These findings highlight the need to clarify the subjective and objective indications for antireflux procedures in infants and children.
Artifacts on Electroencephalograms May Influence the Amplitude-Integrated EEG Classification: A Qualitative Analysis in Neonatal Encephalopathy
Authors: Hagmann Cornelia Franziska , Robertson Nicola Jayne , Azzopardi Denis
Published: December 2006

This is a case report and a descriptive study demonstrating that artifacts are common during long-term recording of amplitude-integrated electroencephalograms and may lead to erroneous classification of the amplitude-integrated electroencephalogram trace. Artifacts occurred in 12% of 200 hours of recording time sampled from a representative sample of 20 infants with neonatal encephalopathy. Artifacts derived from electrical or movement interference occurred with similar frequency; both types of artifacts influenced the voltage and width of the amplitude-integrated electroencephalogram band. This is important knowledge especially if amplitude-integrated electroencephalogram is used as a selection tool for neuroprotection intervention studies.
Guidelines for Monitoring and Management of Pediatric Patients During and After Sedation for Diagnostic and Therapeutic Procedures: An Update
Authors:   American Academy of Pediatrics,   American Academy of Pediatric Dentistry, Coté Charles J. , Wilson Stephen ,   the Work Group on Sedation
Published: December 2006

The safe sedation of children for procedures requires a systematic approach that includes the following: no administration of sedating medication without the safety net of medical supervision; careful presedation evaluation for underlying medical or surgical conditions that would place the child at increased risk from sedating medications; appropriate fasting for elective procedures and a balance between depth of sedation and risk for those who are unable to fast because of the urgent nature of the procedure; a focused airway examination for large tonsils or anatomic airway abnormalities that might increase the potential for airway obstruction; a clear understanding of the pharmacokinetic and pharmacodynamic effects of the medications used for sedation, as well as an appreciation for drug interactions; appropriate training and skills in airway management to allow rescue of the patient; age- and size-appropriate equipment for airway management and venous access; appropriate medications and reversal agents; sufficient numbers of people to carry out the procedure and monitor the patient; appropriate physiologic monitoring during and after the procedure; a properly equipped and staffed recovery area; recovery to presedation level of consciousness before discharge from medical supervision; and appropriate discharge instructions. This report was developed through a collaborative effort of the American Academy of Pediatrics and the American Academy of Pediatric Dentistry to offer pediatric providers updated information and guidance in delivering safe sedation to children.
The Teen Driver
Authors:   Committee on Injury, Violence, and Poison Prevention,   Committee on Adolescence
Published: December 2006

Motor vehicle–related injuries to adolescents continue to be of paramount importance to society. Since the original policy statement on the teenaged driver was published in 1996, there have been substantial changes in many state laws and much new research on this topic. There is a need to provide pediatricians with up-to-date information and materials to facilitate appropriate counseling and anticipatory guidance. This statement describes why teenagers are at greater risk of motor vehicle–related injuries, suggests topics suitable for office-based counseling, describes innovative programs, and proposes preventive interventions for pediatricians, parents, legislators, educators, and other child advocates.
Electron beam-induced surface modification and nano-engineering of carbon nanotubes: Single-walled and multiwalled
Authors: Gupta S. , Patel R.J. , Giedd R.E.
Published: December 2006

Influence of low and medium energy electron beam (E-beam) irradiation on the single-walled (SW) and multiwalled (MW) carbon nanotube films grown by microwave chemical vapor deposition are investigated. These films were subjected to electron beam energy of 50 keV from scanning electron microscope for 2.5, 5.5, 8.0, and 15 h and 100, 200, and 300 keV from transmission electron microscope electron gun for a few minutes to approximately 2 h continuously. To assess the surface modifications/structural degradation, the films were analyzed prior to and post-irradiation using x-ray diffraction and micro-Raman spectroscopy in addition to in situ monitoring by scanning and high-resolution transmission electron microscopy. A minimal increase in intertube or interplanar spacing (i.e., d002) for MW nanotubes ranging from 3.25–3.29 Å (∼3%) can be analogized to change in c-axis of graphite lattice due to thermal effects measured using x-ray diffraction. Resonance Raman spectroscopy revealed that irradiation generated defects in the lattice evaluated through variation of: the intensity of radial breathing mode (RBM), intensity ratio of D to G band (ID/IG), position of D and G bands and their harmonics (D* and G*). The increase in the defect-induced D band intensity, quenching of RBM intensity, and only a slight increase in G band intensity are some of the implications. The MW nanotubes tend to reach a state of saturation for prolonged exposures, while SW transforming semiconducting to quasi-metallic character. Softening of the q = 0 selection rule is suggested as a possible way to explain these results. It is also suggestive that knock-on collision may not be the primary cause of structural degradation, rather a local gradual reorganization, i.e., sp2+δ ⇔ sp2+δ, sp2 C seems quite possible. Experiments showed that with extended exposures, both kinds of nanotubes displayed various local structural instabilities including pinching, graphitization/amorphization, and forming intra-molecular junction (IMJ) within the area of electron beam focus possibly through amorphous carbon aggregates. They also displayed curling and closure forming nano-ring and helix-like structures while mending their dangling bonds. High-resolution transmission electron microscopy electrons corroborated these conclusions. Manufacturing of nanoscale structures “nano-engineering” of carbon-based systems is tentatively ascribed to irradiation-induced solid-state phase transformation, in contrast to conventional nanotube synthesis from the gas phase.
Particle size, uniformity, and mesostructure control of magnetic core/mesoporous silica shell nanocomposite spheres
Authors: Zhao Wenru , Shi Jianlin , Chen Hangrong , Zhang Lingxia
Published: December 2006

Well-structured and monodisperse nanocomposite spheres with a magnetic core/mesoporous silica shell structure (MCMS) were obtained. The effects on the structure and morphology of the MCMS spheres were investigated under various synthesis conditions, including reaction time, quantity of silicate sources of tetraethoxysilane (TEOS) and n-octadecyltrimethoxysilane (C18TMS), ratio of TEOS/C18TMS, and ratio of H2O/EtOH in the starting solution. The particle size of the MCMS spheres and pore diameter are tunable in a certain range with 100% yield. A synthesis mechanism of the mesoporous silica shell was proposed that proceeds via three main stages. The silica shell proved to be effective on protecting the cores from leaching out in acidic conditions.
Analysis of local deformation in indented Ensis Siliqua mollusk shells using Raman spectroscopy
Authors: Scurr David J. , Eichhorn Stephen J.
Published: December 2006

The local deformation surrounding an indented area of Ensis siliqua mollusk shell is characterized using a Raman spectroscopic technique, the findings of which are related to the material’s mechanical function. Microhardness indentation of four directional planes is used to show the marked anisotropy of the structure, where the outer and inner layers of the shell are found to have a significantly higher microhardness value of 4.82 ± 0.02 GPa, compared with transverse and longitudinal cross-sectional values of 3.00 ± 0.07 GPa. This difference is related to the crossed lamellar microstructure of the shell, which is oriented to provide the maximum resistance to external attack from predators. Nanoindentation of the material shows no such anisotropy, giving mean hardness and modulus values for the four directional planes of 3.86 ± 0.10 GPa and 82.4 ± 2.7 GPa respectively, thereby clarifying the prominent role of microstructure in such materials. Scanning electron microscopy of indented samples shows that plastic deformation and delamination occur to different extents, depending on the orientation of the structure and local microstructural features such as prismatic layers. A Raman spectroscopic technique has been used to map relative deformation in the vicinity of the indents, showing that the amount of plastic or permanent deformation can be quantified, and that material delamination can be distinguished from other forms of deformation such as local cracking. These experimental methods are repeated using samples of non-biogenic aragonite, which act as an analogous material for comparison with the shell. It is proposed that the analysis of microhardness indents using Raman spectroscopy could be applied to other biomaterials exhibiting anisotropy.
Influence of Ta content on the physical properties of SrBi2Ta2O9 ferroelectric thin films
Authors: Hsu Fan-Yi , Leu Ching-Chich , Chien Chao-Hsin , Hu Chen-Ti
Published: December 2006

We have investigated the effect that the Ta content has on the ferroelectric properties of strontium bismuth tantalate (SBT) thin films synthesized using metalorganic decomposition (MOD) and spin coating techniques. The physical properties of these SBT samples were strongly dependent upon the Ta ratio. Polarization measurements revealed that Ta-deficient SBT exhibited a relatively low coercive field (2Ec ∼ 87 kV/cm) and a high remanent polarization (2Pr ∼ 15 μC/cm2). The value of 2Pr decreased as the Ta ratio in SBT increased. The improved ferroelectric properties of the Ta-deficient SBT samples may have resulted from the uniformly well-grown bismuth-layered-structured (BLS) phases of the films and their highly preferential orientation along the a and b axes. We suggest that the incorporation of Ta vacancies plays an important role in enhancing the crystallinities and microstructures of Ta-deficient SBT films.
New sharp indentation method of measuring the elastic–plastic properties of compliant and soft materials using the substrate effect
Authors: Zhao Manhong , Chen Xi , Ogasawara Nagahisa , Razvan Anghel Constantin , Chiba Norimasa , Lee Dongyun , Gan Yong X.
Published: December 2006

We propose a new theory with the potential for measuring the elastoplastic properties of compliant and soft materials using one sharp indentation test. The method makes use of the substrate effect, which is usually intended to be avoided during indentation tests. For indentation on a compliant and soft specimen of finite thickness bonded to a stiff and hard testing platform (or a compliant/soft thin film deposited on a stiff/hard substrate), the presence of the substrate significantly enhances the loading curvature which, theoretically, enables the determination of the material power-law elastic-plastic properties by using just one conical indentation test. Extensive finite element simulations are carried out to correlate the indentation characteristics with material properties. Based on these relationships, an effective reverse analysis algorithm is established to extract the material elastoplastic properties. By utilizing the substrate effect, the new technique has the potential to identify plastic materials with indistinguishable indentation behaviors in bulk forms. The error sensitivity and uniqueness of the solution are carefully investigated. Validity and application range of the proposed theory are discussed. In the limit where the substrate is taken to be rigid, the fundamental research is one of the first steps toward understanding the substrate effect during indentation on thin films deposited on deformable substrates.
Antibody Targeting of Stem Cells to Infarcted Myocardium
Authors: Lee Randall J. , Fang Qizhi , Davol Pamela A. , Gu Yiping , Sievers Richard E. , Grabert Ryan C. , Gall Jonathan M. , Tsang Eric , Yee Michael S. , Fok Hubert , Huang Ngan F. , Padbury James F. , Larrick James W. , Lum Lawrence G.
Published: December 2006

Hematopoietic stem cell (HSC) therapy for myocardial repair is limited by the number of stem cells that migrate to, engraft in, and proliferate at sites of injured myocardium. To alleviate this limitation, we studied whether a strategy using a bispecific antibody (BiAb) could target human stem cells specifically to injured myocardium and preserve myocardial function. Using a xenogeneic rat model whereby ischemic injury was induced by transient ligation of the left anterior descending artery (LAD), we determined the ability of a bispecific antibody to target human CD34+ cells to specific antigens expressed in ischemic injured myocardium. A bispecific antibody comprising an anti-CD45 antibody recognizing the common leukocyte antigen found on HSCs and an antibody recognizing myosin light chain, an organ-specific injury antigen expressed by infarcted myocardium, was prepared by chemical conjugation. CD34+ cells armed and unarmed with this BiAb were injected intravenously in rats 2 days postmyocardial injury. Immunohistochemistry studies showed that the armed CD34+ cells specifically localized to the infarcted region of the heart, colocalized with troponin T-stained cells, and colocalization with vascular structures. Compared to unarmed CD34+ cells, the bispecific antibody improved delivery of the stem cells to injured myocardium, and such targeted delivery was correlated with improved myocardial function 5 weeks after infarction (p < .01). Bispecific antibody targeting offers a unique means to improve the delivery of stem cells to facilitate organ repair and a tool to study stem cell biology.
Bone Morphogenetic Protein-4 Enhances Cardiomyocyte Differentiation of Cynomolgus Monkey ESCs in Knockout Serum Replacement Medium
Authors: Hosseinkhani Mohsen , Hosseinkhani Hossein , Khademhosseini Ali , Bolland Fiona , Kobayashi Hisatoshi , Gonzalez Susanna Prat
Published: December 2006

Despite extensive research in the differentiation of rodent ESCs into cardiomyocytes, there have been few studies of this process in primates. In this study, we examined the role of bone morphogenic protein-4 (BMP-4) to induce cardiomyocyte differentiation of cynomolgus monkey ESCs. To study the role of BMP-4, EBs were formed and cultured in Knockout Serum Replacement (KSR) medium containing BMP-4 for 8 days and subsequently seeded in gelatin-coated dishes for 20 days. It was found that ESCs differentiated into cardiomyocytes upon stimulation with BMP-4 in KSR medium, which resulted in a large fraction of beating EBs (∼16%) and the upregulation of cardiac-specific proteins in a dose and time-dependent manner. In contrast, the addition of BMP-4 in FBS-containing medium resulted in a lower fraction of beating EBs (∼6%). BMP-4 acted principally between mesendodermal and mesoderm progenitors and subsequently enhanced their expression. Ultrastructural observation revealed that beating EBs contained mature cardiomyocytes with sarcomeric structures. In addition, immunostaining, reverse transcription-polymerase chain reaction, and Western blotting for cardiac markers confirmed the increased differentiation of cardiomyocytes in these cultures. Moreover, electrophysiological studies demonstrated that the differentiated cardiomyocytes were electrically activated. These findings may be useful in developing effective culture conditions to differentiate cynomolgus monkey ESCs into cardiomyocytes for studying developmental biology and for regenerative medicine.
Synovial Stem Cells Are Regionally Specified According to Local Microenvironments After Implantation for Cartilage Regeneration
Authors: Koga Hideyuki , Muneta Takeshi , Ju Young-Jin , Nagase Tsuyoshi , Nimura Akimoto , Mochizuki Tomoyuki , Ichinose Shizuko , von der Mark Klaus , Sekiya Ichiro
Published: December 2006

We previously demonstrated that synovium-derived MSCs had greater in vitro chondrogenic ability than other mesenchymal tissues, suggesting a superior cell source for cartilage regeneration. Here, we transplanted undifferentiated synovium-derived MSCs into a full-thickness articular cartilage defect of adult rabbits and defined the cellular events to elucidate the mechanisms that govern multilineage differentiation of MSCs. Full-thickness osteochondral defects were created in the knee; the defects were filled with 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate-labeled MSCs and covered with periosteum. After 4 weeks, although the cell density decreased, transplanted MSCs produced a great amount of cartilage matrix extensively. The periosteum became thinner, and chondroprogenitors in the periosteum produced a small amount of cartilage matrix. In the deeper zone, transplanted MSCs progressed to the hypertrophic chondrocyte-like cells. In the deep zone, some transplanted cells differentiated into bone cells and were replaced with host cells thereafter. In the next phase, the border between bone and cartilage moved upwards. In addition, integrations between native cartilage and regenerated tissue were improved. Chondrocyte-like cells derived from the transplanted MSCs still remained at least after 24 weeks. Histological scores of the MSC group improved continuously and were always better than those of two other control groups. Immunohistological analyses and transmission electron microscopy confirmed that the MSCs produced abundant cartilage matrix. We demonstrated that transplanted synovium-derived MSCs were altered over a time course according to the microenvironments. Our results will advance MSC-based therapeutic strategies for cartilage injury and provide the clues for the mechanisms that govern multilineage differentiation of MSCs.
Enhanced Green Fluorescent Protein Is a Nearly Ideal Long-Term Expression Tracer for Hematopoietic Stem Cells, Whereas DsRed-Express Fluorescent Protein Is Not
Authors: Tao Wen , Evans Barbara-Graham , Yao Jing , Cooper Scott , Cornetta Kenneth , Ballas Christopher B. , Hangoc Giao , Broxmeyer Hal E.
Published: December 2006

Validated gene transfer and expression tracers are essential for elucidating functions of mammalian genes. Here, we have determined the suitability and unintended side effects of enhanced green fluorescent protein (EGFP) and DsRed-Express fluorescent protein as expression tracers in long-term hematopoietic stem cells (HSCs). Retrovirally transduced mouse bone marrow cells expressing either EGFP or DsRed-Express in single or mixed dual-color cell populations were clearly discerned by flow cytometry and fluorescence microscopy. The results from in vivo competitive repopulation assays demonstrated that EGFP-expressing HSCs were maintained nearly throughout the lifespan of the transplanted mice and retained long-term multilineage repopulating potential. All mice assessed at 15 months post-transplantation were EGFP positive, and, on average, 24% total peripheral white blood cells expressed EGFP. Most EGFP-expressing recipient mice lived at least 22 months. In contrast, Discosoma sp. red fluorescent protein (DsRed)-expressing donor cells dramatically declined in transplant-recipient mice over time, particularly in the competitive setting, in which mixed EGFP- and DsRed-expressing cells were cotransplanted. Moreover, under in vitro culture condition favoring preservation of HSCs, purified EGFP-expressing cells grew robustly, whereas DsRed-expressing cells did not. Therefore, EGFP has no detectable deteriorative effects on HSCs, and is nearly an ideal long-term expression tracer for hematopoietic cells; however, DsRed-Express fluorescent protein is not suitable for these cells.
Racial Disparity in Hypertensive Disorders of Pregnancy in New York State: A 10-Year Longitudinal Population-Based Study
Authors: Tanaka Masako , Jaamaa Gundegmaa , Kaiser Michelle , Hills Elaine , Soim Aida , Zhu Motao , Shcherbatykh Ivan Y. , Samelson Renee , Bell Erin , Zdeb Michael , McNutt Louise-Anne
Published: December 2006

Objectives. We studied trends of hypertensive disorders of pregnancy by residential socioeconomic status (SES) and racial/ethnic subgroups in New York State over a 10-year period.

Methods. We merged New York State discharge data for 2.5 million women hospitalized with delivery from 1993 through 2002 with 2000 US Census data.

Results. Rates of diagnoses for all hypertensive disorders combined and for preeclampsia individually were highest among Black women across all regions and neighborhood poverty levels. Although hospitalization rates for preeclampsia decreased over time for most groups, differences in rates between White and Black women increased over the 10-year period. The proportion of women living in poor areas remained relatively constant over the same period. Black and Hispanic women were more likely than White women to have a form of diabetes and were at higher risk of preeclampsia; preeclampsia rates were higher in these groups both with and without diabetes than in corresponding groups of White women.

Conclusions. An increasing trend of racial/ethnic disparity in maternal hypertension rates occurred in New York State during the past decade. This trend was persistent after stratification according to SES and other risk factors. Additional research is needed to understand the factors contributing to this growing disparity.
Impact of California’s Proposition 36 on the Drug Treatment System: Treatment Capacity and Displacement
Authors: Hser Yih-Ing , Teruya Cheryl , Brown Alison H. , Huang David , Evans Elizabeth , Anglin M. Douglas
Published: December 2006

Objectives. California’s Proposition 36 offers nonviolent drug offenders community-based treatment as an alternative to incarceration or probation without treatment. We examined how treatment capacity changed to accommodate Proposition 36 clients and whether displacement of other clients was an unintended consequence.

Methods. Treatment admissions were compared for the year before and 2 years after the law was enacted. Surveys of county administrators and treatment providers were conducted in Kern, Riverside, Sacramento, San Diego, and San Francisco counties.

Results. The number of Proposition 36 offenders admitted to treatment continued to increase in the state (approximately 32000 in Year 1 and 48000 in Year 2) and in the 5 counties; total treatment admissions stabilized in Year 2 after increasing in Year 1. Voluntary clients decreased by 8000 each year statewide, but the change varied across counties. One third of treatment providers reported decreased treatment availability for non–Proposition 36 clients in Year 2.

Conclusion. Despite expanded treatment capacity (mostly in outpatient treatment), indirect evidence suggests that displacement of voluntary clients may have occurred in part because of the demand for treatment by Proposition 36 clients.
Multilevel Community-Based Intervention to Increase Access to Sterile Syringes Among Injection Drug Users Through Pharmacy Sales in New York City
Authors: Fuller Crystal M. , Galea Sandro , Caceres Wendy , Blaney Shannon , Sisco Sarah , Vlahov David
Published: December 2006

Objectives. Research has indicated that there is minimal use of pharmacies among injection drug users (IDUs) in specific neighborhoods and among Black and Hispanic IDUs. We developed a community-based participatory research partnership to determine whether a multilevel intervention would increase sterile syringe access through a new policy allowing nonprescription syringe sales in pharmacies.

Methods. We targeted Harlem, NY (using the South Bronx for comparison), and disseminated informational material at community forums, pharmacist training programs, and counseling or outreach programs for IDUs. We compared cross-sectional samples in 3 target populations (pre- and postintervention): community members (attitudes and opinions), pharmacists (opinions and practices), and IDUs (risk behaviors).

Results. Among community members (N = 1496) and pharmacists (N = 131), negative opinions of IDU syringe sales decreased in Harlem whereas there was either no change or an increase in negative opinions in the comparison community. Although pharmacy use by IDUs (N=728) increased in both communities, pharmacy use increased significantly among Black IDUs in Harlem, but not in the comparison community; syringe reuse significantly decreased in Harlem, but not in the comparison community.

Conclusions. Targeting the individual and the social environment through a multilevel community-based intervention reduced high-risk behavior, particularly among Black IDUs.
Prevalence of Posttraumatic Stress Disorder in a Coastal Fishing Village in Tamil Nadu, India, After the December 2004 Tsunami
Authors: Kumar M. Suresh , Murhekar Manoj V. , Hutin Yvan , Subramanian Thilakavathi , Ramachandran Vidya , Gupte Mohan D.
Published: December 2006

Two months after the December 2004 tsunami in Tamil Nadu, India, we surveyed adults aged 18 years or older in a severely affected coastal village using structured interviews and the Harvard Trauma Questionnaire. The prevalence of posttraumatic stress disorder was 12.7% (95% confidence interval [CI]=9.4%, 17.1%), and odds of posttraumatic stress disorder were higher among individuals with no household incomes, women, and those injured during the tsunami.

In addition to promoting feelings of safety, interventions aimed toward populations affected by the December 2004 tsunami need to focus on income-generating activities. Also, there is a need to target initiatives toward women and those individuals injured during the tsunami, given that these groups are more likely to experience posttraumatic stress disorder.
Associations Between Family Support, Family Intimacy, and Neighborhood Violence and Physical Activity in Urban Adolescent Girls
Authors: Kuo JoAnn , Voorhees Carolyn C. , Haythornthwaite Jennifer A. , Young Deborah Rohm
Published: December 2006

We examined the association between various dimensions of the family environment, including family intimacy and involvement in activities, family support for physical activity, and neighborhood violence (perceived and objective) and physical activity among urban, predominantly African American, ninth-grade girls in Balti-more, Md. Greater family intimacy (P = .05) and support (P = .01), but not neighborhood violence, was associated with physical activity. Family factors, including family intimacy and support, are potential targets in physical activity interventions for urban high-school girls.