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1.
J Craniomaxillofac Surg ; 51(9): 528-535, 2023 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-37460350

RESUMEN

INTRODUCTION: The aim of this study was to investigate the orthodontic treatment needs (OTN) of children with RS treated with the TPP in infancy compared to age- and sex-matched controls. METHODS: The aim of this study was to investigate the orthodontic treatment needs (OTN) of children with RS treated with the TPP in infancy compared to age- and sex-matched controls. RESULTS: In 21 children with RS (n = 23; 19 non-syndromic, 4 syndromic; average age 9.9 years) showed high OTN, which was significantly higher than in controls (n = 21). The latter of 9 controls had minor OTN, followed by 8 participants with borderline OTN. Regarding the intraoral picture, patients with RS had an increased open bite tendency. Without considering the presence of a cleft palate, 16 children with RS had high or very high OTN, compared to 4 of controls. CONCLUSIONS: Patients with RS have significantly higher OTN than healthy controls, independent of cleft occurrence. RS is associated with dental anomalies and special skeletal growth patterns, both increasing malocclusion and negatively affecting dentoalveolar growth. This should raise awareness for identifying these needs and provide a comprehensive orthodontic treatment, where functional rehabilitation should be favored over aesthetic results.

2.
AJNR Am J Neuroradiol ; 44(5): 589-594, 2023 05.
Artículo en Inglés | MEDLINE | ID: mdl-36997289

RESUMEN

BACKGROUND AND PURPOSE: Orbital compartment syndrome is a sight-threatening emergency caused by rising pressure inside the orbit. It is usually diagnosed clinically, but imaging might help when clinical findings are inconclusive. This study aimed to systematically evaluate imaging features of orbital compartment syndrome. MATERIALS AND METHODS: This retrospective study included patients from 2 trauma centers. Proptosis, optic nerve length, posterior globe angle, morphology of the extraocular muscles, fracture patterns, active bleeding, and superior ophthalmic vein caliber were assessed on pretreatment CT. Etiology, clinical findings, and visual outcome were obtained from patient records. RESULTS: Twenty-nine cases of orbital compartment syndrome were included; most were secondary to traumatic hematoma. Pathologies occurred in the extraconal space in all patients, whereas intraconal abnormalities occurred in 59% (17/29), and subperiosteal hematoma in 34% (10/29). We observed proptosis (affected orbit: mean, 24.4 [SD, 3.1] mm versus contralateral: 17.7 [SD, 3.1] mm; P < .01) as well as stretching of the optic nerve (mean, 32.0 [SD, 2.5] mm versus 25.8 [SD, 3.4] mm; P < .01). The posterior globe angle was decreased (mean, 128.7° [SD, 18.9°] versus 146.9° [SD, 6.4°]; P < .01). In 69% (20/29), the superior ophthalmic was vein smaller in the affected orbit. No significant differences were detected regarding the size and shape of extraocular muscles. CONCLUSIONS: Orbital compartment syndrome is characterized by proptosis and optic nerve stretching. In some cases, the posterior globe is deformed. Orbital compartment syndrome can be caused by an expanding pathology anywhere within the orbit with or without direct contact to the optic nerve, confirming the pathophysiologic concept of a compartment mechanism.


Asunto(s)
Síndromes Compartimentales , Exoftalmia , Humanos , Órbita/diagnóstico por imagen , Estudios Retrospectivos , Tomografía Computarizada por Rayos X/efectos adversos , Exoftalmia/etiología , Exoftalmia/complicaciones , Síndromes Compartimentales/etiología , Síndromes Compartimentales/complicaciones , Hematoma/diagnóstico por imagen
3.
Int J Oral Maxillofac Surg ; 51(2): 182-190, 2022 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33933334

RESUMEN

Computer-aided microvascular mandible reconstruction is an increasingly common procedure in oral and maxillofacial surgery. The aim of this retrospective single-centre study was to evaluate the rate and specifics of hardware removal after fibula free flap (FFF) fixation with a patient-specific reconstruction plate. The study included patients who underwent hardware removal between April 2017 and October 2019. Statistical analyses were performed regarding the different indications for plate removal (dental implantation versus complication) and the surgical approach (intraoral versus extraoral). Plate removal was performed in 29 of 98 patients (29.6%) after FFF fixation with a patient-specific reconstruction plate. Plate removal was done prior to dental implantation in 58.6% of cases and due to complications in 41.4%. Complications seen between reconstructive surgery and plate removal were less frequent in the dental rehabilitation group (8/17 vs 12/12; P=0.002). Within this group, 35.3% of plates were removed intraorally, and the majority of partial plate removals were performed in the patients with plate removal for dental rehabilitation (72.7% vs 27.3%). Hospitalization was shorter with an intraoral approach (1.7 days vs 4.0 days, P=0.052). The removal of patient-specific reconstruction plates prior to dental implantation is often partial and can be performed intraorally. The use of patient-specific miniplates for fixation of FFF might facilitate later dental rehabilitation.


Asunto(s)
Colgajos Tisulares Libres , Reconstrucción Mandibular , Procedimientos de Cirugía Plástica , Placas Óseas , Trasplante Óseo , Peroné/cirugía , Humanos , Mandíbula/cirugía , Estudios Retrospectivos
4.
Int J Oral Maxillofac Surg ; 48(9): 1156-1162, 2019 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-30792087

RESUMEN

Studies evaluating plate-related complications in patient-specific versus conventional fixation systems in free flap surgery are lacking. This was a retrospective study of 128 osseous free flaps with a minimum follow-up of 12 months. Wound healing disorders, plate exposure, fixation failure, and subtotal osseous union were recorded and evaluated statistically by univariate and regression analysis. Complication rates were as follows: wound healing disorders 33.6% (computer-aided design and computer-aided manufacturing (CAD/CAM) vs. conventional: 35.1% vs. 33.0%); plate exposure 21.9% (29.7% vs. 18.7%); fixation failure 7.0% (8.1% vs. 6.6%); subtotal osseous union 36.7% (45.9% vs. 33.0%). Radiotherapy (P<0.001) and more than two segments (P=0.026) were independent variables for the overall complication rate and were negatively correlated with the dental implantation rate. The time between diagnosis and ablative surgery was increased by 11.0days in the CAD/CAM group (34.2±16.2days vs. 23.2±12.0 days; P=0.002). Rates of dental rehabilitation were not significantly different (35.1% vs. 44.0%, P=0.358). On average, 3.2±1.7 dental implants were placed into flap segments. Plate-related complications were increased with radiotherapy and multisegment flaps. There was a non-significant trend towards increased complications with patient-specific plates in comparison to conventional reconstruction plates.


Asunto(s)
Colgajos Tisulares Libres , Placas Óseas , Diseño Asistido por Computadora , Peroné , Humanos , Estudios Retrospectivos
5.
Int J Oral Maxillofac Surg ; 47(5): 676-682, 2018 May.
Artículo en Inglés | MEDLINE | ID: mdl-29275838

RESUMEN

Free flap surgery is essential for the aesthetic and functional reconstruction of various parts of the body. The aim of this study was to compare current concepts of perioperative flap management between ENT, craniomaxillofacial, and plastic surgeons. A European survey was conducted among 570 surgical departments, covering all aspects of free flap surgery. Focus was placed on antibiotic and antithrombotic drug use, aspects of osseous reconstruction, and flap monitoring strategies. One hundred and seventy-two medical units participated. A broad spectrum of anticoagulant regimens and a trend towards prolonged antibiotic prophylaxis were found. Fixation with (CAD/CAM) reconstruction plates was more popular than monocortical locking with miniplates in the mandible. Visual assessment and Doppler systems were reported to be the most common monitoring modalities. The flap loss rate was stated to be higher after osseous reconstruction. Only a few differences in perioperative flap management were identified between the different surgical fields, and osseous reconstruction appears to be the most challenging.


Asunto(s)
Colgajos Tisulares Libres/estadística & datos numéricos , Cirugía Ortognática , Otolaringología , Pautas de la Práctica en Medicina/estadística & datos numéricos , Cirugía Plástica , Profilaxis Antibiótica , Anticoagulantes/uso terapéutico , Diseño Asistido por Computadora , Diagnóstico por Imagen , Europa (Continente) , Supervivencia de Injerto , Humanos , Fijadores Internos , Encuestas y Cuestionarios
6.
J Craniomaxillofac Surg ; 43(9): 1769-75, 2015 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-26330301

RESUMEN

In the current therapy of head and neck defects, surgical reconstruction with the aid of pedicle or free flaps is common practice. Suitable single flaps are available to solve most reconstructive challenges. However, reconstruction can become a problem in extensive mandibular defects, as they are often caused by large primary tumors or osteoradionecrosis. These composite defects often lead to large intraoral or extraoral fistulas due to the involvement of mucosa, skin, mandible and soft tissue. These issues call for a double flap approach in order to achieve adequate reconstruction. Therefore, we developed a surgical sandwich technique as presented in this study. The procedure features the acquisition and use of two vascular flaps which can be freely combined according to their desired features (for example being of high tissue volume or osteomyocutaneous). In our study we included 11 patients (ten male, one female) with a mean age of 57 years. Seven of the patients had defects due to osteoradionecrosis and four due to tumor resection. A sandwich technique was performed in a single operation in eight patients, whereas for three patients several operations were necessary. The flaps used included: fibula free flap (FFF); anterolateral thigh (ALT); radial forearm flap (RFF); deltopectoral flap (DPF) and tensor fascia lata (TFL). The following combinations were used: FFF and ALT (three cases), FFF and RFF (two), FFF and DPF (three), ALT and TFL (two), and two ALT flaps (one). The sandwich technique proved suitable for complex reconstructions and led to desirable esthetic and functional results. The flexibility in combining different free or pedicle flaps made it possible to address various defect situations and consequently offer satisfactory surgical reconstruction for complex cases.


Asunto(s)
Neoplasias de Cabeza y Cuello/cirugía , Reconstrucción Mandibular/métodos , Osteorradionecrosis/cirugía , Colgajos Quirúrgicos , Adulto , Anciano , Femenino , Neoplasias de Cabeza y Cuello/complicaciones , Humanos , Masculino , Microvasos/cirugía , Persona de Mediana Edad , Osteorradionecrosis/complicaciones , Complicaciones Posoperatorias/cirugía , Estudios Retrospectivos , Colgajos Quirúrgicos/irrigación sanguínea , Resultado del Tratamiento
7.
J Eur Acad Dermatol Venereol ; 29(6): 1082-90, 2015 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-25243910

RESUMEN

BACKGROUND: Secukinumab is a fully human anti-interleukin-17A monoclonal antibody. OBJECTIVE: Determine the efficacy, safety and usability of secukinumab administered via autoinjector/pen. METHODS: This phase III trial randomized subjects with moderate to severe plaque psoriasis to secukinumab 300 mg, 150 mg or placebo self-injection once weekly to Week 4, then every 4 weeks. Co-primary end points at Week 12 were ≥75% improvement in Psoriasis Area and Severity Index (PASI 75) and clear/almost clear skin by investigator's global assessment 2011 modified version (IGA mod 2011 0/1). Secondary end points included autoinjector usability, assessed by successful, hazard-free self-injection and subject-reported acceptability on Self-Injection Assessment Questionnaire. RESULTS: Week 12 PASI 75 and IGA mod 2011 0/1 responses were superior with secukinumab 300 mg (86.7% and 73.3%, respectively) and 150 mg (71.7% and 53.3%, respectively) vs. placebo (3.3% and 0%, respectively) (P < 0.0001 for all). All subjects successfully self-administered treatment at Week 1, without critical use-related hazards. Subject acceptability of autoinjector was high throughout 12 weeks. Adverse events were higher with secukinumab (300 mg, 70.0%; 150 mg, 63.9%) vs. placebo (54.1%), with differences largely driven by mild/moderate nasopharyngitis. CONCLUSION: Secukinumab delivered by autoinjector/pen is efficacious, well-tolerated and associated with high usability in moderate to severe plaque psoriasis.


Asunto(s)
Anticuerpos Monoclonales/administración & dosificación , Fármacos Dermatológicos/administración & dosificación , Psoriasis/tratamiento farmacológico , Jeringas , Adulto , Anticuerpos Monoclonales/efectos adversos , Anticuerpos Monoclonales Humanizados , Fármacos Dermatológicos/efectos adversos , Método Doble Ciego , Diseño de Equipo , Femenino , Cefalea/inducido químicamente , Humanos , Inyecciones Subcutáneas , Interleucina-17/antagonistas & inhibidores , Masculino , Persona de Mediana Edad , Nasofaringitis/inducido químicamente , Satisfacción del Paciente , Prurito/inducido químicamente , Autoadministración/instrumentación , Autoeficacia , Índice de Severidad de la Enfermedad , Resultado del Tratamiento
8.
Neonatology ; 105(4): 332-6, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-24931325

RESUMEN

Caffeine, a methylxanthine and nonspecific inhibitor of adenosine receptors, is an example of a drug that has been in use for more than 40 years. It is one of the most commonly prescribed drugs in neonatal medicine. However, until 2006, it had only a few relatively small and short-term studies supporting its use. It is thanks to the efforts of Barbara Schmidt and the Caffeine for Apnea of Prematurity (CAP) Trial Group that we now have high-quality and reliable data not only on short-term but also long-term outcomes of caffeine use for apnea of prematurity. CAP was an international, multicenter, placebo-controlled randomized trial designed to determine whether survival without neurodevelopmental disability at a corrected age of 18 months is improved if apnea of prematurity is managed without methylxanthines in infants at a high risk of apneic attacks. CAP was kept simple and pragmatic in order to allow for maximum generalizability and applicability. Infants with birth weights of 500-1,250 g were enrolled during the first 10 days of life if their clinicians considered them to be candidates for methylxanthine therapy. The most frequent indication for therapy reported in CAP was treatment of documented apnea, followed by the facilitation of the removal of an endotracheal tube. Only about 20% of the neonatologists in the trial started caffeine for the prevention of apnea and the findings of CAP cannot automatically be extrapolated to an exclusive prophylactic indication. However, recent data suggest that the administration of prophylactic methylxanthine by neonatologists is now common practice.


Asunto(s)
Apnea/tratamiento farmacológico , Cafeína/uso terapéutico , Enfermedades del Prematuro/tratamiento farmacológico , Recien Nacido Prematuro , Pulmón/efectos de los fármacos , Fármacos del Sistema Respiratorio/uso terapéutico , Animales , Apnea/diagnóstico , Apnea/economía , Apnea/fisiopatología , Peso al Nacer , Cafeína/economía , Análisis Costo-Beneficio , Costos de los Medicamentos , Edad Gestacional , Humanos , Recién Nacido , Enfermedades del Prematuro/diagnóstico , Enfermedades del Prematuro/economía , Enfermedades del Prematuro/fisiopatología , Recién Nacido de muy Bajo Peso , Pulmón/fisiopatología , Fármacos del Sistema Respiratorio/economía , Resultado del Tratamiento
9.
Biomed Res Int ; 2014: 373286, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-24822198

RESUMEN

INTRODUCTION: Auricular reconstruction is a great challenge in facial plastic surgery. With the advances in surgical techniques and biotechnology, different options are available for consideration. The aim of this paper is to review the knowledge about the various techniques for total auricular reconstruction based on the literature and our experience. METHODS: Approximately 179 articles published from 1980 to 2013 were identified, and 59 articles were included. We have focused on the current status of total auricular reconstruction based on our personal experience and on papers of particular interest, published within the period of review. We have also included a prospective view on the tissue engineering of cartilage. RESULTS: Most surgeons still practice total auricular reconstruction by employing techniques developed by Brent, Nagata, and Firmin with autologous rib cartilage. Within the last years, alloplastic frameworks for reconstruction have become well established. Choosing the reconstruction techniques depends mainly on the surgeon's preference and experience. Prosthetic reconstruction is still reserved for special conditions, even though the material is constantly improving. Tissue engineering has a growing potential for clinical applicability. CONCLUSION: Auricular reconstruction still receives attention of plastic/maxillofacial surgeons and otolaryngologists. Even though clinical applicability lags behind initial expectations, the development of tissue-engineered constructs continues its potential development.


Asunto(s)
Pabellón Auricular/cirugía , Procedimientos de Cirugía Plástica , Ingeniería de Tejidos , Pabellón Auricular/anatomía & histología , Pabellón Auricular/lesiones , Pabellón Auricular/fisiología , Femenino , Humanos , Masculino
10.
Int J Oral Maxillofac Surg ; 40(1): 94-102, 2011 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-21084173

RESUMEN

The aim of this study was to compare a combination of a locking system with self-tapping (ST-L) or self-drilling-tapping (SDT-L) screws with a combination of conventional miniplates with self-tapping (ST) and self-forming (SF) screws. A standardized osteotomy and osteosynthesis with one of the above mentioned systems was performed in 24 sheep. Callus formation was measured with the help of CT scans assisted by a navigation system. Specimens of each osteotomy gap were taken and examined histologically. The best results were observed when self-tapping screws and the Mini-Locking-System (ST-L) were applied. The slowest healing was seen in animals treated with miniplates and SF screws. After 8 weeks an increase in bone formation could be observed in the ST, SF, SDT-L systems. The results after 8 weeks were comparable with those achieved by the ST-L system after 4 weeks. The improved stability of the osteosynthesis with the ST-L system resulted in early ossification of the osteotomy gap and the smallest amount of callus formation.


Asunto(s)
Placas Óseas , Tornillos Óseos , Mandíbula/cirugía , Aleaciones/química , Animales , Materiales Biocompatibles/química , Fenómenos Biomecánicos , Callo Óseo/diagnóstico por imagen , Callo Óseo/patología , Callo Óseo/fisiología , Diseño de Equipo , Falla de Equipo , Fluoresceínas , Colorantes Fluorescentes , Mandíbula/diagnóstico por imagen , Mandíbula/patología , Osteogénesis/fisiología , Osteotomía/instrumentación , Fenoles , Ovinos , Sulfóxidos , Propiedades de Superficie , Factores de Tiempo , Titanio/química , Tomografía Computarizada por Rayos X , Torque , Xilenos
12.
Plant Biol (Stuttg) ; 11(5): 643-9, 2009 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-19689771

RESUMEN

Long-term nitrogen deposition into forest ecosystems has turned many forests in Central Europe and North America from N-limited to N-saturated systems, with consequences for climate as well as air and groundwater quality. However, complete quantification of processes that convert the N deposited and contributed to ecosystem N cycling is scarce. In this study, we provide the first complete quantification of external and internal N fluxes in an old-growth spruce forest, the Höglwald, Bavaria, Germany, exposed to high chronic N deposition. In this forest, N cycling is dominated by high rates of mineralisation of soil organic matter, nitrification and immobilisation of ammonium and nitrate into microbial biomass. The amount of ammonium available is sufficient to cover the entire N demand of the spruce trees. The data demonstrate the existence of a highly dynamic internal N cycle within the soil, driven by growth and death of the microbial biomass, which turns over approximately seven times each year. Although input and output fluxes are of high environmental significance, they are low compared to the internal fluxes mediated by microbial activity.


Asunto(s)
Ecosistema , Nitrógeno/metabolismo , Picea/metabolismo , Biomasa , Alemania , Suelo/análisis , Microbiología del Suelo
13.
J Infect Dis ; 179(3): 714-6, 1999 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-9952384

RESUMEN

Previous studies on macrophages have shown that Toxoplasma gondii alters the metabolism of arachidonic acid with subsequent inability to generate leukotrienes (LT)s. LTB4 and LTC4 were analyzed in cerebrospinal fluid of 3 groups of human immunodeficiency virus (HIV) type 1-seropositive patients: with toxoplasmic encephalitis (TE) (n=10), with herpes simplex encephalitis (n=5), and without encephalitis (n=10) and in HIV-1-seronegative controls without inflammatory diseases (n=30) by specific immunoassays and gas chromatography-mass spectrometry. In HIV-1-seropositive subjects with TE, LTB4 and LTC4 were below the detection limit (<5.0 pg/mL) and thus significantly decreased (P<.01) compared with HIV-1-seropositive patients with herpes simplex encephalitis (LTB4, 148.5+/-47.6 pg/mL; LTC4, 116.4+/-36.9 pg/mL) and in those without encephalitis (LTB4, 46.1+/-16.8 pg/mL; LTC4, 48.3+/-21.3 pg/mL), and in controls (LTB4, 43.6+/-21.2; LTC4, 45.2+/-18.9 pg/mL). These results point to an essential role of inhibition of 5-lipoxygenase with subsequent failure of LT release as an important mechanism for the survival of T. gondii in vivo.


Asunto(s)
Encefalitis/parasitología , Seropositividad para VIH/líquido cefalorraquídeo , Leucotrieno B4/líquido cefalorraquídeo , Leucotrieno C4/líquido cefalorraquídeo , Toxoplasmosis Cerebral/líquido cefalorraquídeo , Toxoplasmosis Cerebral/complicaciones , Adulto , Anciano , Encefalitis/líquido cefalorraquídeo , Encefalitis/complicaciones , Encefalitis/virología , Encefalitis Viral/líquido cefalorraquídeo , Encefalitis Viral/complicaciones , Cromatografía de Gases y Espectrometría de Masas , Seropositividad para VIH/complicaciones , VIH-1 , Herpes Simple/líquido cefalorraquídeo , Herpes Simple/complicaciones , Humanos , Persona de Mediana Edad
14.
J Cancer Educ ; 11(4): 196-202, 1996.
Artículo en Inglés | MEDLINE | ID: mdl-8989632

RESUMEN

BACKGROUND: With the identification of the breast cancer susceptibility genes BRCA1 and BRCA2, clinical testing for detection of the mutated genes may be available in the near future. Primary care physicians increasingly serve as full-service providers and gatekeepers and must be aware of presymptomatic testing in order to counsel their patients appropriately. To address this educational need, a new module was incorporated into the genetics course taken by first-year medical students at the Medical College of Virginia. METHODS: The module used small groups, led by genetics faculty and members of the Virginia Breast Cancer Foundation, for discussion of case examples. The medical students' knowledge of and attitudes toward cancer and predictive genetic testing were assessed by a pretest and a posttest. RESULTS: After the module, knowledge scores increased by 27%, and significant changes were seen in the students' attitudes toward issues such as the regulation of testing availability and the psychological effect of testing. Most students consistently felt that predictive genetic testing is beneficial, that they would have the testing themselves, that genetic counseling should be required for testing, and that insurers' access to genetic testing results should be limited. Overall, the module was received favorably by all participants. CONCLUSIONS: Small-group discussion of relevant case examples increases knowledge and awareness of issues regarding presymptomatic genetic testing for breast cancer.


Asunto(s)
Neoplasias de la Mama/diagnóstico , Educación de Pregrado en Medicina , Pruebas Genéticas , Neoplasias de la Mama/prevención & control , Evaluación Educacional , Femenino , Conocimientos, Actitudes y Práctica en Salud , Humanos , Evaluación de Programas y Proyectos de Salud , Estadísticas no Paramétricas , Virginia
15.
Radiat Environ Biophys ; 32(2): 137-50, 1993.
Artículo en Inglés | MEDLINE | ID: mdl-8337358

RESUMEN

The amount of Chernobyl-derived 137Cs transferred to the soil by stemflow, throughfall (precipitation under the tree crown), and leaf-fall from three beeches was investigated as a function of time in the growing seasons of 1991 and 1992. Up to 70 Bq/week was deposited with the stemflow, mainly in dissolved form (< 0.45 micron) rather than in particulate form (> 0.45 micron). The ratio of dissolved radiocesium to particulate radiocesium was about 10 in the stemflow. It varied considerably with time, but since these variations followed the same pattern for all three trees, they indicated a common cause to be responsible for the fractionation of radiocesium (e.g. meterological conditions for bark weathering). A significant correlation was observed for the amount of dissolved 137Cs (in Bq) and the amount of stemflow (in liters). The 137Cs concentration in the stemflow (in Bq/1), however, decreased with increasing stemflow intensity (in Bq/week). For particulate radiocesium such correlations were not detected. Up to 5 Bq/m2 per week was deposited with the throughfall from the canopy, mainly in particulate form (ratio dissolved radiocesium to particulate radiocesium = 0.34). The mean total annual amounts of 137Cs deposited to the ground (dissolved+particulate) for the three trees were: stemflow: 1991 600 Bq; 1992 460 Bq; throughfall: 1991 and 1992 approximately 100 Bq/m2 each; leaffall: 1992 approximately 10 Bq/m2. The data indicate that at present a substantial amount of the radiocesium in the leaves derives already from root uptake.


Asunto(s)
Accidentes , Radioisótopos de Cesio , Reactores Nucleares , Ceniza Radiactiva , Contaminantes Radiactivos del Suelo , Árboles , Alemania , Ucrania
16.
Sci Total Environ ; 78: 77-87, 1989 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-2717928

RESUMEN

The time dependence of the specific activity of Chernobyl-derived 134Cs, 137Cs and 106Ru was determined in vegetation and soil samples from an old spruce stand within a period of 600 days after the beginning of the radioactive fallout. The results show that 70% of the total activity of radiocesium and 60% of radioruthenium deposited in the spruce stand were retained initially in the canopy. They were removed from the needles and twigs as a result of weathering (rain, wind, litter fall) and transferred to the forest floor, but only rather slowly (half-lives in the canopy: radiocesium, 90 days for the period 0-130 days, 230 days for the period 130-600 days; radioruthenium, 95 days for the period 0-200 days). The transfer of radiocesium and ruthenium to the forest floor by litter-fall was small when compared with that of weathering by rain or wind (radiocesium 7%, radioruthenium 8%, with respect to the total activity deposited in the canopy). The total deposition of radiocesium and ruthenium in the spruce stand was higher by 20 and 24%, respectively, than that observed in nearby grassland. The deposition velocity of radiocesium in the spruce stand was estimated at 5.5 mm s-1, higher by a factor of 10 than the figure for grassland. Similar values were found for radioruthenium.


Asunto(s)
Accidentes , Radioisótopos de Cesio/análisis , Reactores Nucleares , Plantas/análisis , Radioisótopos de Rutenio/análisis , Alemania Oriental , Humanos , Árboles , Ucrania , Tiempo (Meteorología)
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