RESUMEN
The northeast of Madagascar is as diverse as it is threatened. The area bordering the Analanjirofo and SAVA regions contains six protected areas and at least 22 lemur species. Many applied research and conservation programs have been established in the region with the aim of ensuring both wildlife and people thrive in the long term. While most of the remaining humid evergreen forest of northeast Madagascar is formally protected, the local human population depends heavily on the land, and unsustainable natural resource use threatens this biodiversity hotspot. Drawing from our collective experiences managing conservation activities and research programs in northeast Madagascar, we discuss the major threats to the region and advocate for eight conservation activities that help reduce threats and protect the environment, providing specific examples from our own programs. These include (1) empowering local conservation actors, (2) ensuring effectively protected habitat, (3) expanding reforestation, (4) establishing and continuing long-term research and monitoring, (5) reducing food insecurity, (6) supporting environmental education, (7) promoting sustainable livelihoods, and (8) expanding community health initiatives. Lastly, we provide a list of actions that individuals can take to join us in supporting and promoting lemur conservation.
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Lemur , Lemuridae , Humanos , Animales , Madagascar , Conservación de los Recursos Naturales , Ecosistema , BiodiversidadRESUMEN
BACKGROUND: Neuromuscular blockade is required to control excessive muscle contractions during electroconvulsive therapy (ECT). In a crossover, assessor-blinded, prospective randomized study, we studied the minimum effective dose (MED) of succinylcholine and rocuronium for ECT. The MED was the lowest dose to provide a predefined qualitative measure of acceptable control of muscle strength during induced convulsions. METHODS: Succinylcholine (0.8 mg kg) or rocuronium (0.4 mg kg) was randomly administered in 227 ECT sessions to 45 patients. The dose was incrementally increased or decreased by 10% based on 2 psychiatrists' (blinded to treatment) assessment of "acceptable" or "not acceptable" control of evoked muscle contractions (sufficient versus insufficient or excessive paralysis). The neuromuscular transmission was monitored quantitatively until full recovery. RESULTS: In our study, the MEDs of succinylcholine and rocuronium to produce acceptable ECT conditions in 50% of patients (MED50ECT) were 0.85 mg kg (95% confidence interval [CI], 0.77-0.94) and 0.41 mg kg (95% CI, 0.36-0.46) and in 90% of patients (MED90ECT) were 1.06 mg kg (95% CI, 1.0-1.27) and 0.57 mg kg (95% CI, 0.5-0.6), respectively. Nadir twitch height for acceptable muscle activity was 0% (0-4) and 4% (0-30; P < 0.001), respectively, and the time to recovery of the neuromuscular transmission was 9.7 ± 3.5 and 19.5 ± 5.7 minutes, respectively. CONCLUSIONS: A twitch suppression of >90% is needed for control of motor contractions during ECT. The initial ECT dose of succinylcholine should be selected based on each patient's preprocedural condition, ranging between 0.77 and 1.27 mg kg to produce acceptable muscle blockade in 50% to 90% of patients. Rocuronium-neostigmine combination is a safe alternative if appropriately dosed (0.36-0.6 mg kg) and monitored.
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Androstanoles/administración & dosificación , Terapia Electroconvulsiva/métodos , Fármacos Neuromusculares Despolarizantes/administración & dosificación , Fármacos Neuromusculares no Despolarizantes/administración & dosificación , Succinilcolina/administración & dosificación , Adulto , Anciano , Anciano de 80 o más Años , Estudios Cruzados , Relación Dosis-Respuesta a Droga , Femenino , Humanos , Masculino , Persona de Mediana Edad , Contracción Muscular/efectos de los fármacos , Contracción Muscular/fisiología , Estudios Prospectivos , Rocuronio , Método Simple Ciego , Resultado del Tratamiento , Adulto JovenRESUMEN
PURPOSE: Little is known about the use of electroconvulsive therapy (ECT) for adolescent psychiatric patients in China. This study examined the frequency of ECT and the demographic and clinical correlates of adolescent psychiatric patients hospitalized in a tertiary psychiatric hospital in China. METHODS: This was a retrospective chart review of 954 inpatients aged between 13 and 17 years treated over a period of 8 years (2007-2013). Sociodemographic and clinical data were collected from the electronic chart management system for discharged patients. RESULTS: The rate of ECT use was 42.6% in the whole sample (46.5% for patients with schizophrenia, 41.8% for major depressive disorder, 57.8% for bipolar disorders, and 23.9% for other diagnoses). Use of ECT was independently and positively associated with older age, high aggression risk at time of admission, and use of antipsychotics and antidepressants. Compared with patients with schizophrenia, those with other psychiatric diagnoses were less likely to receive ECT. The above significant correlates explained 32% of the variance of ECT use (P < 0.001). Limitations of this study included the lack of data regarding the efficacy and side effects of ECT. Furthermore, the high rate of ECT applied only to 1 setting which limits the ability to extrapolate the implications of the results to other populations. CONCLUSIONS: The use of ECT was exceedingly high in adolescent patients treated in a tertiary clinical centre in China. It is unlikely that such a high rate of ECT use is found across China or that such practice reflects standard of care for psychiatrically ill adolescents. The underlying reasons for the high use of ECT at this center warrant urgent investigations.
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Psiquiatría del Adolescente/métodos , Terapia Electroconvulsiva/métodos , Trastornos Mentales/terapia , Adolescente , Pueblo Asiatico , Trastorno Bipolar/terapia , China/epidemiología , Trastorno Depresivo Mayor/terapia , Terapia Electroconvulsiva/tendencias , Femenino , Hospitalización/estadística & datos numéricos , Humanos , Masculino , Trastornos Mentales/epidemiología , Trastornos Mentales/psicología , Psicotrópicos/uso terapéutico , Estudios Retrospectivos , Riesgo , Esquizofrenia/epidemiología , Esquizofrenia/terapia , Factores Socioeconómicos , Suicidio/estadística & datos numéricosRESUMEN
BACKGROUND: Electroconvulsive therapy (ECT) continues to be an effective treatment option for patients who fail to respond to pharmacological interventions, are unable to tolerate medications, and show a suboptimal response to behavioral and psychotherapeutic treatments. However, risks for cognitive impairment may contribute to some patients' refusal of ECT. METHODS: The present study examined galantamine as a pharmacological intervention to reduce cognitive adverse effects from ECT. Thirty-nine inpatients diagnosed with major depressive disorder; bipolar disorder, depressed type; or schizoaffective disorder, depressed type and admitted for ECT were randomized to galantamine or placebo. Study drugs were initiated 24 to 48 hours before starting ECT and continued throughout the course of ECT. A neuropsychological test battery was administered at baseline and 24 to 48 hours after completing a course of ECT treatments. Depression severity was monitored using the 17-item Hamilton Rating Scale for Depression and Clinical Global Impression Scale at baseline, weekly, and end point. Self-rated adverse effects were monitored weekly. RESULTS: Thirty participants (12 patients in the galantamine group, 18 patients in the placebo group) had both pretreatment and posttreatment neuropsychological ratings. Those in the galantamine group scored significantly higher at discharge for delayed memory (t28 = 2.44, P < 0.05). Hierarchical regressions examined if treatment condition predicted changes in delayed memory scores from baseline to discharge. Inclusion of the treatment condition in the final model made a significant incremental improvement in prediction (ΔR = 0.12, F1,27 change = 4.65, P < 0.05; ß = 0.37, t = 2.16, P < 0.05). Galantamine was well tolerated with no clinically significant bradycardia or prolonged paralysis when administered with ECT. CONCLUSIONS: Galantamine may be protective against impairment in retention of new learning. Galantamine exhibited minimal adverse effects and was safe when administered during ECT. The present findings require replication by future researchers using larger samples before broad conclusions can be drawn.
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Amnesia Anterógrada/etiología , Amnesia Anterógrada/prevención & control , Terapia Electroconvulsiva/efectos adversos , Galantamina/uso terapéutico , Nootrópicos/uso terapéutico , Afecto/fisiología , Cognición/fisiología , Estudios de Cohortes , Trastorno Depresivo Mayor/psicología , Trastorno Depresivo Mayor/terapia , Método Doble Ciego , Femenino , Galantamina/efectos adversos , Humanos , Pacientes Internos , Masculino , Persona de Mediana Edad , Pruebas Neuropsicológicas , Nootrópicos/efectos adversos , Escalas de Valoración Psiquiátrica , Trastornos Psicóticos/psicología , Trastornos Psicóticos/terapiaRESUMEN
BACKGROUND: Expressive writing and motivational interviewing are well-known approaches to help patients cope with stressful life events. Although these methods are often applied by human counselors, it is less well understood if an automated artificial intelligence approach can benefit patients. Providing an automated method would help expose a wider range of people to the possible benefits of motivational interviewing, with lower cost and more adaptability to sudden events like the COVID-19 pandemic. OBJECTIVE: This study presents an automated writing system and evaluates possible outcomes among participants with respect to behavior related to the COVID-19 pandemic. METHODS: We developed a rule-based dialogue system for "Expressive Interviewing" to elicit writing from participants on the subject of how COVID-19 has impacted their lives. The system prompts participants to describe their life experiences and emotions and provides topic-specific prompts in response to participants' use of topical keywords. In May 2021 and June 2021, we recruited participants (N=151) via Prolific to complete either the Expressive Interviewing task or a control task. We surveyed participants immediately before the intervention, immediately after the intervention, and again 2 weeks after the intervention. We measured participants' self-reported stress, general mental health, COVID-19-related health behavior, and social behavior. RESULTS: Participants generally wrote long responses during the task (53.3 words per response). In aggregate, task participants experienced a significant decrease in stress in the short term (~23% decrease, P<.001) and a slight difference in social activity compared with the control group (P=.03). No significant differences in short-term or long-term outcomes were detected between participant subgroups (eg, male versus female participants) except for some within-condition differences by ethnicity (eg, higher social activity among African American people participating in Expressive Interviewing vs participants of other ethnicities). For short-term effects, participants showed different outcomes based on their writing. Using more anxiety-related words was correlated with a greater short-term decrease in stress (r=-0.264, P<.001), and using more positive emotion words was correlated with a more meaningful experience (r=0.243, P=.001). As for long-term effects, writing with more lexical diversity was correlated with an increase in social activity (r=0.266, P<.001). CONCLUSIONS: Expressive Interviewing participants exhibited short-term, but not long-term, positive changes in mental health, and some linguistic metrics of writing style were correlated with positive change in behavior. Although there were no significant long-term effects observed, the positive short-term effects suggest that the Expressive Interviewing intervention could be used in cases in which a patient lacks access to traditional therapy and needs a short-term solution. TRIAL REGISTRATION: Clincaltrials.gov NCT05949840; https://www.clinicaltrials.gov/study/NCT05949840.
RESUMEN
The mechanical properties of carbon nanotubes such as low density, high stiffness, and exceptional strength make them ideal candidates for reinforcement material in a wide range of high-performance composites. Molecular dynamics simulations are used to predict the tensile response of fibers composed of aligned carbon nanotubes with intermolecular bonds of interstitial carbon atoms. The effects of bond density and carbon nanotube length distribution on fiber strength and stiffness are investigated. The interstitial carbon bonds significantly increase load transfer between the carbon nanotubes over that obtained with van der Waals forces. The simulation results indicate that fibers with tensile strengths to 60 GPa could be produced by employing interstitial cross-link atoms. The elastic modulus of the fibers is also increased by the bonds.
RESUMEN
When pyrimidine-functionalized carbon nanotubes were incubated with single-stranded DNA ligase, formations of macroscopic aggregates were observed. Wet-cell transmission electron microscopy imaging revealed that the nanotubes were radially bound to form a 3D latticelike structure. These structures were not observed in control reactions lacking ligase or adenosine triphosphate. Raman spectroscopy analysis revealed no spectra indicative of carbon nanotubes in ligase-unamended controls; however, spectra were observed in radial breathing mode and in the G and G' bands in reactions containing ligase. Furthermore, the addition of deoxyribonuclease to the ligated reactions dispersed the aggregates, and a reduction in Raman spectral intensity was observed.
Asunto(s)
ADN Ligasas/metabolismo , ADN/química , Nanotubos de Carbono/química , Nanotubos de Carbono/ultraestructura , ADN/metabolismo , Microscopía Electrónica de Transmisión , Nanotecnología , Espectrometría Raman , TemperaturaRESUMEN
The purpose of this study was to quantify the concentrations of crude protein, fat, ash, neutral detergent fiber, acid detergent fiber, lignin, nonstructural carbohydrates, and gross energy in plant foods consumed by wild black and white ruffed lemurs (Varecia variegata). Calcium, phosphorous, magnesium, potassium, sodium, iron, zinc, copper, manganese, molybdenum, and selenium concentrations were also determined. A total of 122 samples from 33 plant families and more than 60 species were collected and analyzed for their nutritional content. The specific nutrient needs of black and white ruffed lemurs are unknown, but quantifying the nutritional composition of the foods they consume in the wild will help nutritionists and veterinarians formulate more appropriate diets for captive ruffed lemurs. This information will also supply information on how man-induced habitat changes affect the nutritional composition of foods consumed by free-ranging lemurs.
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Fenómenos Fisiológicos Nutricionales de los Animales , Dieta , Análisis de los Alimentos , Lemur/fisiología , Plantas/química , Animales , Química Analítica , Madagascar , Oligoelementos/análisisRESUMEN
This retrospective population-based study assessed the long-term risk of repeat reported occupational injury or illness incidents among Veterans Health Administration (VHA) nursing employees. Using fiscal year (FY) 2002 as the start date for the longitudinal surveillance of incidents, descriptive analyses included all VHA nursing employees (N = 25,697) who reported an initial (index) incident that occurred between FY 2002 and FY 2005. Adjusted for total administrative loss rates (e.g., attrition, disability, retirements), approximately half of the "surviving" index cases reported repeat incidents during an ensuing 3-year period. This total increased to approximately two thirds during a 6-year period. Compared to their nurse counterparts, practical nurses and nursing assistants had higher cumulative probabilities of multiple reported repeat occupational injury or illness incidents. Study findings suggest that reported levels of repeat occupational injury or illness incidents represent a complex interplay between environmental factors (e.g., location) and nursing staff demographics (e.g., level of education).
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Accidentes de Trabajo/estadística & datos numéricos , Personal de Enfermería en Hospital , Enfermedades Profesionales/etiología , Salud Laboral , Adulto , Escolaridad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Enfermedades Profesionales/epidemiología , Recurrencia , Sistema de Registros , Estudios Retrospectivos , Riesgo , Ausencia por Enfermedad/estadística & datos numéricos , Estados Unidos/epidemiología , United States Department of Veterans AffairsRESUMEN
Environmental education programs are critically important for raising awareness about global and local environmental concerns, by providing the knowledge, tools, and means for young and old generations to cope with current challenges. Of the greatest importance is the implementation of environmental education programs in biodiversity hotspots where environmental crises are high and resources to fund mitigation programs are low. Madagascar is one such priority hotspot, featuring intensive wildlife-human conflicts due to shrinking natural environments. The Duke Lemur Center-SAVA Conservation Initiative has been conducting environmental education activities in the SAVA region, northeastern Madagascar, since 2011. These activities have been aimed at increasing awareness of local and global environmental issues and at stimulating the involvement of local school students. Our initiatives have predominantly supported teacher trainings to provide teachers with environmental education content, examples, and recommendations on how to integrate activities into their regular curricula, commonly referred to as a "cascade approach". Due to logistical hurdles, including high teacher turnover rates, however, these interventions have not been monitored to assess their efficacy. Thus, to better inform current and future interventions, we designed and implemented classroom-based surveys to gather baseline data on the basic knowledge of SAVA students and their perceptions of the environment. We identify informational gaps in surveyed schools, including those located in large towns vs. villages, and those with trained vs. untrained teachers. Based on these results, we make recommendations for future environmental education efforts in the region, including activities that could address real-life environmental problems and decision-making solutions.
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Conservación de los Recursos Naturales , Ciencia Ambiental/educación , Humanos , Madagascar , Maestros , Instituciones Académicas , Estudiantes , Encuestas y Cuestionarios , Vida SilvestreRESUMEN
BACKGROUND: In spite of its global importance, the interaction between depression and chronic comorbid diseases remains incompletely understood with regard to prevalence, severity of disease, and potential causative factors mediating this interaction. OBJECTIVE: The authors sought to compare overall medical costs in nondepressed and depressed individuals. METHOD: Insurance claims for 618,780 patients were examined for total annual non-mental health cost of care in 11 chronic diseases. In each disease cohort, median annual non-mental health cost was calculated for individuals with and without depression. RESULTS: Patients with depression had higher median per-patient annual non-mental health costs than patients without depression in all 11 diseases studied. There was a higher-than-random comorbidity between depression and all 11 chronic comorbid diseases. CONCLUSION: Even when controlling for number of chronic comorbid diseases, depressed patients had significantly higher costs than non-depressed patients, in a magnitude consistent across 11 chronic comorbid diseases.
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Depresión/economía , Costos de la Atención en Salud , Adulto , Estudios de Casos y Controles , Enfermedad Crónica/economía , Costo de Enfermedad , Estudios Transversales , Femenino , Humanos , Masculino , Estados UnidosRESUMEN
OBJECTIVES: The purpose of this study was to: (1) assess the effectiveness of galantamine in the prevention of cognitive impairments during ECT treatment and (2) to explore the safety and tolerability of galantamine during ECT treatment. METHODS: Nine consecutive ECT patients were given galantamine 4 mg bid throughout the course of their ECT treatments followed by a second cohort of eight consecutive ECT patients who did not receive galantamine. Objective measures of cognitive functioning and depression severity were performed pre-ECT and post-ECT. Subjective ratings of depression, confusion, and side effects were obtained weekly. RESULTS: The two groups were similar in age, gender and admission Global Assessment Functioning (GAF) scores. There were no significant between group differences found with regards to mean seizure duration, energy administered to induce seizures, blood pressure, or heart rate during and post-ECT treatment. None of the patients discontinued galantamine due to side effects and there were no severe adverse drug reactions. Patients receiving galantamine performed significantly better on delayed memory and abstract reasoning following ECT. The galantamine group showed a greater but non-significant mood improvement (repeated measure ANOVA). CONCLUSIONS: Our data support the hypothesis that galantamine may reduce cognitive impairment during ECT, especially with regards to new learning. In addition, galantamine may also enhance the antidepressant action of ECT. Galantamine was both safe and well tolerated during ECT.
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Inhibidores de la Colinesterasa/farmacología , Trastornos del Conocimiento/etiología , Trastornos del Conocimiento/prevención & control , Trastorno Depresivo Mayor/terapia , Terapia Electroconvulsiva/efectos adversos , Galantamina/farmacología , Inhibidores de la Colinesterasa/administración & dosificación , Trastornos del Conocimiento/diagnóstico , Trastorno Depresivo Mayor/diagnóstico , Trastorno Depresivo Mayor/psicología , Femenino , Galantamina/administración & dosificación , Paro Cardíaco/inducido químicamente , Humanos , Masculino , Persona de Mediana Edad , Fármacos Neuromusculares Despolarizantes/efectos adversos , Pruebas Neuropsicológicas , Proyectos Piloto , Índice de Severidad de la Enfermedad , Succinilcolina/efectos adversosRESUMEN
OBJECTIVE: To describe 2 cases of encephalitis with neuropsychiatric symptoms including catatonia, compounded by neuroleptic use for delirious agitation culminating in malignant catatonia responsive to electroconvulsive therapy (ECT). BACKGROUND: Neuropsychiatric symptoms including catatonia can be manifestations of limbic encephalitis and encephalitides of unidentified etiology, including encephalitis lethargica. Catatonic features are often difficult to appraise in this context. This can easily lead to the use of neuroleptics, which may precipitate worsening of catatonia. METHOD: Medical, neurologic, and psychiatric histories, physical examination findings, results of laboratory, imaging and neurophysiologic investigations, and treatment response with medications and ECT were recorded. RESULTS: Both patients showed significant improvement with ECT. CONCLUSIONS: Malignant catatonia can complicate encephalitis lethargica and idiopathic limbic encephalitis, which already carry high mortality rates. When neuroleptics are used for agitation in cases of encephalitis, physicians must be wary of precipitating malignant catatonia and neuroleptics should be discontinued when such a danger emerges. Although lorazepam is helpful in treating catatonia, it may not suffice, as in the cases presented. ECT deserves serious consideration early in the course of malignant catatonia and for catatonia nested in encephalopathy secondary to encephalitis, unresolved with lorazepam.
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Catatonia/terapia , Terapia Electroconvulsiva , Encefalitis/terapia , Adulto , Catatonia/etiología , Líquido Cefalorraquídeo/citología , Resistencia a Medicamentos , Quimioterapia Combinada , Electroencefalografía , Encefalitis/etiología , Femenino , Estudios de Seguimiento , Humanos , Linfocitosis/líquido cefalorraquídeo , Escala del Estado Mental , Examen Neurológico , Agitación Psicomotora/etiología , Agitación Psicomotora/terapia , Psicotrópicos/uso terapéuticoAsunto(s)
Antidepresivos/uso terapéutico , Aneurisma de la Aorta Abdominal/psicología , Trastorno Depresivo Mayor/diagnóstico , Trastorno Depresivo/diagnóstico , Terapia Electroconvulsiva , Anciano , Terapia Combinada , Trastorno Depresivo/terapia , Trastorno Depresivo Mayor/complicaciones , Trastorno Depresivo Mayor/terapia , Diagnóstico Diferencial , Fatiga/psicología , Bloqueo Cardíaco/psicología , Humanos , Masculino , Psicoterapia , Tomografía Computarizada por Rayos XRESUMEN
Many patients with Huntington's disease (HD) develop psychiatric symptoms such as depression and psychosis. For severe symptoms, electroconvulsive therapy (ECT) can be a valuable treatment. In this case series, we identified seven patients with HD who received ECT at Massachusetts General Hospital in the past 20 years. In all cases, ECT was well tolerated and produced improvement in psychiatric and behavioral symptoms. Our case series supports the hypothesis of a positive risk-benefit ratio for ECT in patients with HD and severe depression or psychosis.
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Trastorno Depresivo/terapia , Terapia Electroconvulsiva , Enfermedad de Huntington/psicología , Trastornos Psicóticos/terapia , Adulto , Trastorno Depresivo/complicaciones , Trastorno Depresivo/psicología , Femenino , Humanos , Enfermedad de Huntington/complicaciones , Masculino , Persona de Mediana Edad , Trastornos Psicóticos/complicaciones , Trastornos Psicóticos/psicología , Estudios Retrospectivos , Resultado del Tratamiento , Adulto JovenAsunto(s)
Anestesia General/efectos adversos , Trastorno Bipolar/terapia , Terapia Electroconvulsiva/efectos adversos , Esclerosis Múltiple Recurrente-Remitente/fisiopatología , Seguridad , Corticoesteroides/efectos adversos , Corticoesteroides/uso terapéutico , Adulto , Encéfalo/patología , Comorbilidad , Trastorno Depresivo Mayor/terapia , Femenino , Humanos , Imagen por Resonancia Magnética , Esclerosis Múltiple Recurrente-Remitente/diagnóstico , Esclerosis Múltiple Recurrente-Remitente/tratamiento farmacológico , Esclerosis Múltiple Recurrente-Remitente/psicología , Médula Espinal/patología , Resultado del TratamientoRESUMEN
Electroconvulsive therapy (ECT) is a treatment for affective catatonia and requires multiple general anesthetics. Morbid obesity is an increasingly prevalent condition that may complicate the standard anesthetic management of a patient undergoing ECT. We report the successful airway management of a morbidly obese ECT patient via elective tracheostomy.
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Catatonia/terapia , Depresión/terapia , Terapia Electroconvulsiva , Obesidad Mórbida/complicaciones , Traqueostomía/métodos , Catatonia/complicaciones , Humanos , Masculino , Persona de Mediana EdadRESUMEN
We performed tight-binding molecular dynamics on single-walled carbon nanotubes with and without a variety of defects to study their effect on the nanotube modulus and failure through bond rupture. For a pristine (5,5) nanotube, Young's modulus was calculated to be approximately 1.1 TPa, and brittle rupture occurred at a strain of 17% under quasistatic loading. The predicted modulus is consistent with values from experimentally derived thermal vibration and pull test measurements. The defects studied consist of moving or removing one or two carbon atoms, and correspond to a 1.4% defect density. The occurrence of a Stone-Wales defect does not significantly affect Young's modulus, but failure occurs at 15% strain. The occurrence of a pair of separated vacancy defects lowers Young's modulus by approximately 160 GPa and the critical or rupture strain to 13%. These defects apparently act independently, since one of these defects alone was independently determined to lower Young's modulus by approximately 90 GPa, also with a critical strain of 13%. When the pair of vacancy defects adjacent, however, Young's modulus is lowered by only approximately 100 GPa, but with a lower critical strain of 11%. In all cases, there is noticeable strain softening, for instance, leading to an approximately 250 GPa drop in the apparent secant modulus at 10% strain. When a chiral (10,5) nanotube with a vacancy defect was subjected to tensile strain, failure occurred through a continuous spiral-tearing mechanism that maintained a high level of stress (2.5 GPa) even as the nanotube unraveled. Since the statistical likelihood of defects occurring near each other increases with nanotube length, these studies may have important implications for interpreting the experimental distribution of moduli and critical strains.
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BACKGROUND: Intraperitoneal (IP) cefazolin and ceftazidime are recommended as empiric treatment for peritoneal dialysis (PD)-associated peritonitis. Human peritoneal mesothelial cells (HPMCs) may be affected by high IP cefazolin and ceftazidime concentrations. Peritoneal dialysate cancer antigen-125 (CA-125) appearance rate can be used to measure HPMC damage. OBJECTIVE: To determine whether IP cefazolin and ceftazidime increase peritoneal CA-125 appearance rate. METHODS: The study consisted of 2 phases. In phase I, no antibiotic was administered, and in phase II, patients received IP cefazolin and ceftazidime (15 mg/kg rounded to nearest 100 mg). Phase II occurred immediately after phase I. Each phase used a 4-hour dwell time with 2 L of dextrose 2.5% dialysate. Dialysate samples were collected at 0, 0.5, 1, 2, and 4 hours during each phase. Samples were assayed for CA-125, and CA-125 appearance rate was calculated. RESULTS: Thirteen patients were recruited (7 men; aged 44.0 +/-16.0 y). The mean +/- SD (range) CA-125 dialysate concentration after phases I and II were 6.6 +/- 3.7 U/mL (2.3-15.0) and 6.4 +/-3.8 U/mL (1.6-13.8), respectively (p = 0.46). The CA-125 appearance rate after phases I and II were 51.9 +/- 31.3 U/min/1.73 m(2) (13.8-113.0) and 50.5 +/- 32.9 U/min/1.73 m(2) (11.0-104.0), respectively (p = 0.57). The slopes of the regression lines of CA-125 appearance rate were not significantly different between phases I and II. CONCLUSIONS: These findings demonstrate that concurrently administered IP cefazolin and ceftazidime have no effect on HPMC release of CA-125 in non-infected PD patients.