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OBJECTIVE: We sought to determine whether thoracic electrical impedance tomography (EIT) could characterize pulmonary function in amyotrophic lateral sclerosis (ALS) patients, including those with facial weakness. Thoracic EIT is a noninvasive, technology in which a multi-electrode belt is placed across the chest, producing real-time impedance imaging of the chest during breathing. METHODS: We enrolled 32 ALS patients and 32 age- and sex-matched healthy controls (HCs) without underlying lung disease. All participants had EIT measurements performed simultaneously with standard pulmonary function tests (PFTs), including slow and forced vital capacity (SVC and FVC) in upright and supine positions and maximal inspiratory and expiratory pressures (MIPs and MEPs, respectively). Intraclass correlation coefficients (ICCs) were calculated to assess the immediate reproducibility of EIT measurements and Pearson's correlations were used to explore the relationships between EIT and PFT values. RESULTS: Data from 30 ALS patients and 27 HCs were analyzed. Immediate upright SVC reproducibility was very high (ICC 0.98). Correlations were generally strongest between EIT and spirometry measures, with R values ranging from 0.64 to 0.82 (p < 0.001) in the ALS cohort. There were less robust correlations between EIT values and both MIPs and MEPs in the ALS patients, with R values ranging from 0.33 to 0.44. There was no significant difference for patients with and without facial weakness. There were no reported adverse events. CONCLUSION: EIT-based pulmonary measures hold the promise of providing an alternative approach for lung function assessment in ALS patients. Based on these early results, further development and study of this technology are warranted.
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Esclerose Lateral Amiotrófica , Impedância Elétrica , Testes de Função Respiratória , Humanos , Esclerose Lateral Amiotrófica/fisiopatologia , Esclerose Lateral Amiotrófica/diagnóstico por imagem , Esclerose Lateral Amiotrófica/diagnóstico , Feminino , Masculino , Pessoa de Meia-Idade , Testes de Função Respiratória/métodos , Idoso , Tomografia/métodos , Adulto , Reprodutibilidade dos Testes , Capacidade Vital/fisiologia , Pulmão/fisiopatologia , Pulmão/diagnóstico por imagemRESUMO
Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is an important therapy for patients with T-cell lymphomas, including cutaneous T-cell lymphoma (CTCL), adult T-cell lymphoma (ATL), and peripheral T-cell lymphoma (PTCL). Mogamulizumab is an anti-CCR4 antibody that has been associated with an increased risk of transplant-related complications in retrospective analyses of ATL, particularly when administered within 50 days before transplantation. This post hoc analysis of 3 clinical trials examined safety and outcome data for 32 patients with CTCL (n = 23), ATL (n = 7), or PTCL (n = 2) who underwent allo-HSCT after mogamulizumab treatment. Overall, 22 patients (69%) were known to have graft-versus-host disease (GVHD), 8 patients (25%) did not report GVHD, and 2 patients (6%) had unknown GVHD status. Fourteen patients with known GVHD underwent transplantation between 50 and 365 days after their last dose of mogamulizumab, while 2 underwent transplantation within 50 days after treatment. Based on this limited evidence, GVHD was not associated with the time interval from last mogamulizumab dose to transplantation.
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Anticorpos Monoclonais Humanizados , Doença Enxerto-Hospedeiro , Transplante de Células-Tronco Hematopoéticas , Transplante Homólogo , Humanos , Anticorpos Monoclonais Humanizados/efeitos adversos , Anticorpos Monoclonais Humanizados/administração & dosagem , Anticorpos Monoclonais Humanizados/uso terapêutico , Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Estudos Retrospectivos , Pessoa de Meia-Idade , Masculino , Feminino , Adulto , Doença Enxerto-Hospedeiro/etiologia , Doença Enxerto-Hospedeiro/prevenção & controle , Idoso , Linfoma de Células T/terapia , Resultado do TratamentoRESUMO
ABSTRACT: Transfusion-associated circulatory overload (TACO) is the leading cause of transfusion-related deaths in the United States, accounting for more than 30% of fatalities reported to the Food and Drug Administration between 2016 and 2020. However, TACO is widely considered to be an underdiagnosed and underreported complication of blood transfusions, and its exact incidence is unknown. One of the reasons for this is a lack of recognition of TACO and its signs and symptoms, especially as the definition of TACO has been updated twice since 2018 without full dissemination to nurses, who are responsible for bedside care of patients during and following blood transfusions. This article seeks to bridge this gap by discussing the updated definitions and signs and symptoms of TACO, as well as the management of this treatable blood transfusion reaction.
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Reação Transfusional , Humanos , Fatores de Risco , Transfusão de Sangue , IncidênciaRESUMO
Hypermobile Ehlers-Danlos syndrome (hEDS) is a common disorder in children and adolescents that negatively impacts health-related quality of life (HRQOL). It can include chronic pain, fatigue, autonomic dysfunction, and mood problems. The objective of this study was to examine levels of agreement between children and parents in the setting of hEDS and HRQOL. Individuals with hEDS, ages 10-20 years, and their parents were recruited to complete a series of surveys. Instruments included pediatric quality of life generic and multidimensional fatigue scales, Functional Disability Index, Pain-Frequency-Severity-Duration scale, Brief Illness Perception Questionnaire, and Herth Hope Index. Agreement on each measure was evaluated using statistical calculations. Thirty-six parent-child dyads completed the surveys. There were no significant differences between the means of parent and child scores. There was moderate to strong agreement on all survey scores. However, the proportion of dyads with disagreement was relatively high for each individual score. Eighteen dyads disagreed on at least half of the surveys. Body mass index centile and child perception of cognitive fatigue most strongly predicted disagreement in total HRQOL score. Proxy-reporters for children and adolescents with hEDS may agree with their child on average. However, due to significant frequency of clinically important disagreement, information from both children and their parents should be sought whenever possible.
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BACKGROUND: Ovarian sex cord-stromal tumors (OSCTs) are rare ovarian tumors that can develop from sex cord, stromal cells, or both. OSCTs can be benign or malignant. Bilateral and/or unilateral ovarian fibromas, a type of OSCT of the stromal cells, have been reported in individuals diagnosed with nevoid basal cell carcinoma syndrome (NBCCS). Calcified ovarian fibromas have been reported in 15-25% of individuals diagnosed with NBCCS while 75% of those cases occur bilaterally. The average age at diagnosis of OSCT/ovarian fibromas in patients with NBCSS is in the second to third decade compared with age 50 in the general population. Ovarian tumors are rare in pediatric populations. METHODS: The patient is a 5-year-old female diagnosed with bilateral ovarian fibromas at age 4. Multigene panel for the patient and subsequent targeted molecular evaluation of parents were completed. Histological evaluations on the surgically resected ovaries were performed for microscopic characterization of fibromas. RESULTS: Germline testing identified de novo heterozygous novel likely pathogenic variants in PTCH1 gene, exon 12 deletion, and an SMARCA4 splicing variant c.2002-1G > A. Microscopic examination of bilateral tumors was consistent with an ovarian fibroma. CONCLUSIONS: To our knowledge, this is the first report of bilateral benign ovarian fibroma in a child with a diagnosis of nevoid basal cell carcinoma syndrome (NBCCS) with a potential predisposition to Rhabdoid Tumor Predisposition Syndrome (RTPS).
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Síndrome do Nevo Basocelular , Fibroma , Neoplasias Ovarianas , Síndrome do Nevo Basocelular/genética , Criança , Pré-Escolar , DNA Helicases/genética , Feminino , Fibroma/complicações , Fibroma/diagnóstico , Fibroma/genética , Células Germinativas , Humanos , Pessoa de Meia-Idade , Proteínas Nucleares/genética , Neoplasias Ovarianas/diagnóstico , Neoplasias Ovarianas/genética , Fatores de Transcrição/genéticaRESUMO
Spiritual care is a critical aspect of end-of-life care that is often undervalued and underaddressed by hospice health care teams. The purpose of this quality improvement project was to determine if the implementation of an evidence-based spiritual care protocol changed practices regarding the initial assessment of spiritual needs, frequency of reassessment of needs, the inclusion of spiritual interventions, and staff perspectives on spiritual care. The preimplementation and postimplementation data evaluation displayed increased compliance with spiritual needs assessment within 5 days of admission, increased reassessment intervals, an increase in the percentage of interactions that included spiritual interventions, and improved staff perspectives on spiritual care. The findings of the study support implementation of a spiritual care protocol in hospice patients.
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Cuidados Paliativos na Terminalidade da Vida , Hospitais para Doentes Terminais , Terapias Espirituais , Assistência Terminal , Cuidados Paliativos na Terminalidade da Vida/métodos , Humanos , Espiritualidade , Assistência Terminal/métodosRESUMO
Many pediatric oncology patients and their families may benefit from genetic counseling and testing; however, identifying the best timing and delivery method for these referrals is sometimes a challenge. The goal of this study was to understand how and when caregivers prefer to receive information about genetic counseling and testing. A total of 56 surveys completed by caregivers at The Johns Hopkins Hospital Pediatric Oncology unit in Baltimore, Maryland were analyzed. A sizeable subset of respondents was interested in receiving information about the availability of genetic counseling from an oncology doctor or nurse, but not a genetic counselor (n=13/55, 24%). Most respondents preferred to be informed about genetic services at diagnosis (n=28/54, 52%) or within 1 to 2 months of diagnosis (n=14/54, 26%). In conclusion, patients and their families may benefit from prompt and early recognition of the risk of cancer predisposition syndromes, preferably within the first 2 months following diagnosis. Oncology professionals are an important source of information, and can introduce the availability of genetic counseling services and motivate families to undergo genetic testing, though alternative communication methods such as brochures may also be useful.
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Aconselhamento Genético , Neoplasias , Criança , Aconselhamento Genético/psicologia , Testes Genéticos , Humanos , Oncologia , Neoplasias/diagnóstico , Neoplasias/genética , Inquéritos e QuestionáriosRESUMO
Here, we report the draft genome sequences of four aerobic gaseous alkane-oxidizing bacteria isolated from soil by enrichment culture using isobutane (2-methylpropane) as the sole carbon and energy source. The sequences all reveal microorganisms with multiple alkane-oxidizing monooxygenases, including soluble di-iron monooxygenases (SDIMOs), copper-containing monooxygenases (CuMMOs), and alkane hydroxylases (AHs).
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OBJECTIVE: To determine how the method of presenting testing options and a provider recommendation can influence a decision about genetic testing for inherited cancer predispositions. METHODS: An online hypothetical vignette study was completed by 454 healthy volunteers. Participants were randomized to receive one of two survey versions which differed by genetic testing choice presentation. One group was shown three options simultaneously (no test, 5-gene or 15-gene), and a second group received the 15-gene option after choosing between the no test and 5-gene options. A preference-based provider recommendation was also incorporated. We examined the effect of these interventions on test selection. RESULTS: Participants in the simultaneous group were more likely to choose a genetic test than those in the sequential group (OR: 2.35, p=0.003). This effect was no longer observed when individuals who had selected no-test in the sequential group were told about the 15-gene test (OR: 1.03 p=0.932). Incorporating a provider recommendation into the hypothetical scenario led to more preference-consistent choices (χ2 = 8.53, p < 0.0035,). CONCLUSIONS: A larger menu of testing choices led to higher testing uptake. A preference-based clinician recommendation resulted in more preference-consistent choices. PRACTICE IMPLICATIONS: The structuring of testing options and preference-sensitive recommendations appear to facilitate informed testing decisions.
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Testes Genéticos , Neoplasias , Humanos , Neoplasias/diagnóstico , Neoplasias/genética , Inquéritos e QuestionáriosRESUMO
Implementation and adherence to consensus statement criteria for referral of pediatric cancer patients for genetic evaluation are critical to identify the 5% to 10% with a genetic cancer predisposition syndrome. The authors implemented a Plan-Do-Study-Act quality improvement initiative aimed at increasing referrals of at-risk patients. Retrospective chart review was followed by educational intervention-with impact assessed over a 9-month prospective chart review. Referral rate improved >2-fold and there was an improvement in documented oncologic history to at least a third-degree relative. The integration of quality improvement can be an effective tool to improve the referral of patients with an elevated risk for a cancer predisposition syndrome.
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Neoplasias/genética , Criança , Predisposição Genética para Doença , Testes Genéticos , Humanos , Oncologia , Mutação , Estudos RetrospectivosRESUMO
BACKGROUND: Medical treatment informed by Precision Medicine is becoming a standard practice for many diseases, and patients are curious about the consequences of genomic variants in their genome. However, most medical students' understanding of Precision Medicine derives from classroom lectures. This format does little to foster an understanding for the potential and limitations of Precision Medicine. To close this gap, we implemented a hands-on Precision Medicine training program utilizing exome sequencing to prepare a clinical genetic report of cadavers studied in the anatomy lab. The program reinforces Precision Medicine related learning objectives for the Genetics curriculum. METHODS: Pre-embalmed blood samples and embalmed tissue were obtained from cadavers (donors) used in the anatomy lab. DNA was isolated and sequenced and illustrative genetic reports provided to the students. The reports were used to facilitate discussion with students on the implications of pathogenic genomic variants and the potential correlation of these variants in each "donor" with any anatomical anomalies identified during cadaver dissection. RESULTS: In 75% of cases, analysis of whole exome sequencing data identified a variant associated with increased risk for a disease/abnormal condition noted in the donor's cause of death or in the students' anatomical findings. This provided students with real-world examples of the potential relationship between genomic variants and disease risk. Our students also noted that diseases associated with 92% of the pathogenic variants identified were not related to the anatomical findings, demonstrating the limitations of Precision Medicine. CONCLUSION: With this study, we have established protocols and classroom procedures incorporating hands-on Precision Medicine training in the medical student curriculum and a template for other medical educators interested in enhancing their Precision Medicine training program. The program engaged students in discovering variants that were associated with the pathophysiology of the cadaver they were studying, which led to more exposure and understanding of the potential risks and benefits of genomic medicine.
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Anatomia , Educação de Graduação em Medicina , Estudantes de Medicina , Anatomia/educação , Cadáver , Currículo , Humanos , Medicina de Precisão , Análise de Sequência de DNARESUMO
OBJECTIVE: Pulmonary function tests (PFTs) are important for assessing respiratory function in amyotrophic lateral sclerosis (ALS) patients. However, weakness of oral and glottal closure, due to concomitant bulbar dysfunction, may result in unreliable PFT values stemming from leakage of air around the breathing tube and through the glottis. In this study, we assessed whether standard thoracic electrical impedance tomography (EIT) could serve as a surrogate measure for PFTs. APPROACH: Thoracic EIT was performed simultaneously with standard PFTs on seven ALS patients without clinical bulbar weakness (six men and one woman, mean age of 63 years) and ten healthy volunteers (seven men and three women, mean age of 57 years). A raw impedance metric along with more standard EIT measures were computed and correlated with the normalized forced vital capacity (FVC). Additionally, test/re-test metrics and EIT images were analyzed. MAIN RESULTS: The impedance metric was found to be robust and sensitive to lung activity. We also identified qualitative EIT differences between healthy volunteers and ALS patients, with the ALS images showing greater heterogeneity. Significant correlations with FVC were found for both impedance and EIT metrics in ALS patients (r2 = 0.89) and for the impedance metric only in healthy volunteers (r2 = 0.49). SIGNIFICANCE: This suggests that EIT, using our novel impedance metric, has the potential to serve as an alternative technology to standard PFTs for assessing pulmonary function in patients with ALS, offering new metrics of disease status for those with bulbar weakness.
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Esclerose Lateral Amiotrófica/fisiopatologia , Testes de Função Respiratória/métodos , Estudos de Casos e Controles , Impedância Elétrica , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
The incidence of melanoma continues to increase worldwide. In the United States, melanoma is the fifth most common cancer in men and the sixth most common cancer in women. The risk factors contributing to melanoma have largely remained unchanged, but there is a new focus on modifiable risk factors including sun exposure and ultraviolet light. A large public initiative supported by the Centers for Disease Control focuses on educating the public on the risks of sun exposure and indoor tanning. Early detection and resection of melanoma lesions is necessary to prevent metastasis and reduce medical costs.
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Melanoma/epidemiologia , Neoplasias Cutâneas/epidemiologia , Raios Ultravioleta/efeitos adversos , Humanos , Melanoma/etiologia , Fatores de Risco , Neoplasias Cutâneas/etiologia , Banho de Sol , Luz Solar/efeitos adversos , Estados Unidos/epidemiologiaRESUMO
Hypermobile Ehlers-Danlos syndrome (hEDS) is a hereditary disorder of connective tissue, often presenting with complex symptoms can include chronic pain, fatigue, and dysautonomia. Factors influencing functional disability in the pediatric hEDS population are incompletely studied. This study's aims were to assess factors that affect quality of life in children and adolescents with hEDS. Individuals with hEDS between the ages 12-20 years and matched parents were recruited through retrospective chart review at two genetics clinics. Participants completed a questionnaire that included the Pediatric Quality of Life Inventory (PedsQL™), PedsQL Multidimentional Fatigue Scale, Functional Disability Inventory, Pain-Frequency-Severity-Duration Scale, the Brief Illness Perception Questionnaire, measures of anxiety and depression, and helpful interventions. Survey responses were completed for 47 children and adolescents with hEDS/hypermobility spectrum disorder (81% female, mean age 16 years), some by the affected individual, some by their parent, and some by both. Clinical data derived from chart review were compared statistically to survey responses. All outcomes correlated moderately to strongly with each other. Using multiple regression, general fatigue and pain scores were the best predictors of the PedsQL total score. Additionally, presence of any psychiatric diagnosis was correlated with a lower PedsQL score. Current management guidelines recommend early intervention to prevent disability from deconditioning; these results may help identify target interventions in this vulnerable population.
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Síndrome de Ehlers-Danlos/patologia , Instabilidade Articular/patologia , Qualidade de Vida , Adolescente , Adulto , Criança , Síndrome de Ehlers-Danlos/genética , Feminino , Humanos , Instabilidade Articular/genética , Masculino , Estudos Retrospectivos , Inquéritos e Questionários , Adulto JovemRESUMO
The objective of this study was to explore the factors contributing to quality of life in pediatric patients with non-vascular Ehlers-Danlos syndromes (EDS). Data were analyzed on 41 children with a diagnosis of non-vascular EDS from the de-identified data available from the National Institute on Aging (NIA) study of heritable disorders of connective tissue. Children under age 19 years were seen as part of a long-term evaluation project from 2003 to 2013 on a larger natural history of patients with heritable disorders of connective tissue. Data collected included medical history, physical examination findings, diagnostic study results, and responses on validated questionnaires. We reviewed a sub-cohort of children with a diagnosis of non-vascular EDS and explored pain severity and interference via the Brief Pain Inventory, and sleep quality via the Pittsburgh Sleep Quality Index. Pain severity had a strong correlation with pain interference, and both were similar to other disorders that include chronic pain reported in the literature. Sleep quality did not correlate with pain severity or interference, but all patients had poor sleep quality in comparison to historical controls. We conclude that pain and sleep are significant issues in the pediatric non-vascular EDS population, and future research may be directed toward these issues.
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Síndrome de Ehlers-Danlos/epidemiologia , Medição da Dor , Qualidade de Vida , Sono , Adolescente , Criança , Síndrome de Ehlers-Danlos/complicações , Síndrome de Ehlers-Danlos/diagnóstico , Feminino , Humanos , Masculino , Inquéritos e QuestionáriosRESUMO
Caregivers of children with autism spectrum disorder (ASD) may find it difficult to feel a sense of control and to cope with the overall physical and emotional demands of caring for their child. While caregivers are able to successfully cope with a high level of stress, there are limits to their resources and abilities to cope over time. Genetic counselors working with affected families may be able to help parents more effectively manage stress related to the disorder. Few short-term interventions have been reported in genetic counseling yet implementation of evidence-based examples may be achievable. This study aimed to assess the feasibility of a coping effectiveness training (CET) intervention designed to enhance coping self-efficacy (CSE) among caregivers of children with ASD, with the eventual goal of translating this intervention into genetic counseling practice. A randomized treatment-control design was used to investigate the feasibility of an intervention using CET among caregivers of children with ASD. The primary outcome was the feasibility of the intervention; the secondary outcome was improvements in CSE in the intervention group as compared to the control group. Caregivers were recruited and randomized into the treatment (n=15) or control (n=13) groups. Of these, 22 completed the study (retention: 78.6%). The intervention was highly feasible; most caregivers found the CET helpful, practical, useful, and relatively easy to attend. The treatment group demonstrated significantly increased CSE from pre-intervention to post-intervention (p=0.02). Between group differences were not significant when comparing the pre-post changes. We provide preliminary evidence that CET may be beneficial to caregivers of children with ASD. The results of this feasibility study support development of a phase II study of this intervention in a larger cohort, aimed to be implemented into a genetic counseling setting.
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Transtorno do Espectro Autista/psicologia , Transtorno do Espectro Autista/terapia , Cuidadores/psicologia , Aconselhamento Genético/métodos , Pais/educação , Adaptação Psicológica , Adulto , Criança , Pré-Escolar , Estudos de Coortes , Estudos de Viabilidade , Feminino , Humanos , Masculino , Pais/psicologia , Autoeficácia , Apoio SocialRESUMO
Pseudomonas mendocina KR1 oxidizes the gasoline oxygenate methyl tertiary butyl ether (MTBE) to tertiary butyl alcohol (TBA) during growth on C5 -C8 n-alkanes. We have further explored oxidation of ether oxygenates by this strain to help identify the enzyme that catalyses these reactions. High levels of MTBE-oxidizing activity occurred in resting cells grown on C5 -C8 n-alkanes. Lower activities occurred in cells grown on longer-chain n-alkanes (C9 -C11 ) and 1°-alcohols (C5 -C10 ). N-octane-grown cells also oxidized tertiary amyl methyl ether (TAME) to tertiary amyl alcohol (TAA), but did not oxidize ethyl tertiary butyl ether (ETBE), TBA or TAA. A 39 kDa polypeptide in whole cell extracts of n-octane-grown cells strongly cross-reacted with an anti-AlkB polyclonal antiserum in an SDS-PAGE/immunoblot. This polypeptide was absent or less abundant in cells grown on dextrose, dextrose plus dicyclopropylketone or 1-octanol. N-octane-grown cells of Pseudomonas aeruginosa strains KSLA-473 and ATCC 17423 oxidized MTBE and TAME but not ETBE. N-hexadecane-grown cells of these strains and strain PAO1 did not oxidize any of the oxygenates tested. Our results indicate ether oxygenate-degrading activity in alkane-utilizing pseudomonads is consistently observed with close homologues of the GPo1 non-haem-iron alkane hydroxylases but is otherwise not a consistent catalytic feature of these diverse enzymes.
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This study examined the prevalence, predictors, and outcomes of spanking and verbal punishment in 2,573 low-income White, African American, and Mexican American toddlers at ages 1, 2, and 3. Both spanking and verbal punishment varied by maternal race/ethnicity. Child fussiness at age 1 predicted spanking and verbal punishment at all 3 ages. Cross-lagged path analyses indicated that spanking (but not verbal punishment) at age 1 predicted child aggressive behavior problems at age 2 and lower Bayley mental development scores at age 3. Neither child aggressive behavior problems nor Bayley scores predicted later spanking or verbal punishment. In some instances, maternal race/ethnicity and/or emotional responsiveness moderated the effects of spanking and verbal punishment on child outcomes.
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Adaptação Psicológica , Educação Infantil/etnologia , Educação Infantil/psicologia , Relações Mãe-Filho/etnologia , Punição/psicologia , Negro ou Afro-Americano/psicologia , Negro ou Afro-Americano/estatística & dados numéricos , Fatores Etários , Agressão , Comportamento Infantil/etnologia , Comportamento Infantil/psicologia , Transtornos do Comportamento Infantil/etnologia , Desenvolvimento Infantil , Pré-Escolar , Comparação Transcultural , Feminino , Humanos , Lactente , Entrevistas como Assunto , Masculino , Comportamento Materno/etnologia , Americanos Mexicanos/psicologia , Americanos Mexicanos/estatística & dados numéricos , Pobreza/etnologia , Pobreza/psicologia , Fatores Socioeconômicos , Estados Unidos , População Branca/psicologia , População Branca/estatística & dados numéricosRESUMO
Carbon isotopic enrichment factors (epsilonC) measured during cometabolic biodegradation of methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), and tert-amyl methyl ether (TAME) by Pseudonocardia tetrahydrofuranoxydans strain K1 were -2.3 +/- 0.2 per thousand, -1.7 +/- 0.2 per thousand, and -1.7 +/- 0.3 per thousand, respectively. The measured carbon apparent kinetic isotope effect was 1.01 for all compounds, consistent with the expected kinetic isotope effects for both oxidation of the methoxy (or ethoxy) group and enzymatic SN1 biodegradation mechanisms. Significantly, delta13C measurements of the tert-butyl alcohol and tert-amyl alcohol products indicated that the tert-butyl and tert-amyl groups do not participate in the reaction and confirmed that ether biodegradation by strain K1 involves oxidation of the methoxy (or ethoxy) group. Measured hydrogen isotopic enrichment factors (epsilonH) were -100 +/- 10 per thousand, -73 +/- 7 per thousand, and -72 +/- 20 per thousand for MTBE, ETBE, and TAME respectively. Previous results reported for aerobic biodegradation of MTBE by Methylibium petroleiphilum PM1 and Methylibium R8 showed smaller epsilonH values (-35 per thousand and -42 per thousand, respectively). Plots of Delta2H/Delta13C show different slopes for strain K1 compared with strains PM1 and R8, suggesting that different mechanisms are utilized by K1 and PM1/R8 during aerobic MTBE biodegradation.