RESUMO
BACKGROUND: The bispectral index (BIS) monitor is a quantitative electroencephalographic (EEG) device that is widely used to assess the hypnotic component of anaesthesia, especially when neuromuscular blocking drugs are used. It has been shown that the BIS is sensitive to changes in electromyogram (EMG) activity in anaesthetized patients. A single study using an earlier version of the BIS showed that decreased EMG activity caused the BIS to decrease even in awake subjects, to levels that suggested deep sedation and anaesthesia. METHODS: We administered suxamethonium and rocuronium to 10 volunteers who were fully awake, to determine whether the BIS decreased in response to neuromuscular block alone. An isolated forearm technique was used for communication during the experiment. Two versions of the BIS monitor were used, both of which are in current use. Sugammadex was used to antagonise the neuromuscular block attributable to rocuronium. RESULTS: The BIS decreased after the onset of neuromuscular block in both monitors, to values as low as 44 and 47, and did not return to pre-test levels until after the return of movement. The BIS showed a two-stage decrease, with an immediate reduction to values around 80, and then several minutes later, a sharp decrease to lower values. In some subjects, there were periods where the BIS was <60 for several minutes. The response was similar for both suxamethonium and rocuronium. Neither monitor was consistently superior in reporting the true state of awareness. CONCLUSIONS: These results suggest that the BIS monitor requires muscle activity, in addition to an awake EEG, in order to generate values indicating that the subject is awake. Consequently, BIS may be an unreliable indicator of awareness in patients who have received neuromuscular blocking drugs. CLINICAL TRIAL REGISTRY NUMBER: ACTRN12613000587707.
Assuntos
Eletroencefalografia/efeitos dos fármacos , Bloqueio Neuromuscular , Adulto , Androstanóis/farmacologia , Cognição/efeitos dos fármacos , Eletromiografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Rocurônio , Succinilcolina/farmacologia , Voluntários , VigíliaRESUMO
BACKGROUND: Surveillance is an acknowledged method to decrease nosocomial infections, such as surgical site infections (SSIs). Electronic healthcare records create the opportunity for automated surveillance. While approaches for different types of surgeries and indicators already exist, there are very few for obstetrics and gynaecology. AIM: To analyse the sensitivity and workload reduction of semi-automated surveillance in obstetrics and gynaecology. METHODS: In this retrospective, single-centre study at a 1438-bed tertiary care hospital in Germany, semi-automated SSI surveillance using the indicators 'antibiotic prescription', 'microbiological data' and 'administrative data' (diagnosis codes, readmission, post-hospitalization care) was compared with manual analysis and categorization of all patient files. Breast surgeries (BSs) conducted in 2018 and caesarean sections (CSs) that met the inclusion criteria between May 2013 and December 2019 were included. Indicators were analysed for sensitivity, number of analysed procedures needed to identify one case, and potential workload reduction in detecting SSIs in comparison with the control group. FINDINGS: The reference standard showed nine SSIs in 416 BSs (2.2%). Sensitivities for the indicators 'antibiotic prescription', 'diagnosis code', 'microbiological sample taken', and the combination 'diagnosis code or microbiological sample' were 100%, 88.9%, 66.7% and 100%, respectively. The reference standard showed 54 SSIs in 3438 CSs (1.6%). Sensitivities for the indicators 'collection of microbiological samples', 'diagnosis codes', 'readmission/post-hospitalization care', and the combination of all indicators were 38.9%, 27.8%, 85.2% and 94.4%, respectively. CONCLUSIONS: Semi-automated surveillance systems may reduce workload by maintaining high sensitivity depending on the type of surgery, local circumstances and thorough digitalization.
Assuntos
Infecção Hospitalar , Ginecologia , Gravidez , Feminino , Humanos , Estudos Retrospectivos , Controle de Infecções , Infecção Hospitalar/microbiologia , Infecção da Ferida Cirúrgica/epidemiologia , Infecção da Ferida Cirúrgica/prevenção & controle , Infecção da Ferida Cirúrgica/diagnóstico , Antibacterianos/uso terapêuticoRESUMO
BACKGROUND: The aim of the present study was to determine whether regular exercise training (ET) is effective at promoting the mobilization of CPCs and improving their functional activity in patients with recently acquired myocardial infarction (STEMI). Regular physical training has been shown to improve myocardial perfusion and cardiovascular function. This may be related in part to a mobilization of bone marrow-derived circulating progenitor cells (CPCs) as well as an enhanced vascularisation. METHODS: 37 patients with STEMI were randomly assigned to an ET group or a non-ET group (controls). Two weeks after STEMI, three weeks after regular ET and three months after ET, BNP levels, exercise echocardiography and exercise spiroergometry were evaluated. The number of CD34+/CD45+ and CD133+/CD45+ CPCs was measured by flow cytometry analysis. The migration capacity of the CPCs was determined with a boyden chamber and the clonogenic capacity by CFU-assay. RESULTS: In the ET-group the number and migration capacity of CPCs increased significantly after regular exercise training. The BNP level decreased significantly from 121 +/- 94 to 75 +/- 47 pg/ml (p<0.001) after the ET period, the left ventricular ejection fraction raised in parallel at peak exercise, and the cardiorespiratory condition improved as demonstrated by an increase of VO2max (from 1641 +/- 522 to 1842 +/- 724 ml/min, p<0.02). These three effects persist till three months after the ET period. CONCLUSIONS: Regular physical activity appears to predispose the mobilization and enhanced functional activity of CPCs, a phenomenon which might lead to an improved cardiac function in patients with recently acquired acute myocardial infarction.
Assuntos
Células da Medula Óssea/metabolismo , Terapia por Exercício/métodos , Exercício Físico/fisiologia , Mobilização de Células-Tronco Hematopoéticas/métodos , Infarto do Miocárdio/reabilitação , Antígeno AC133 , Idoso , Antígenos CD/sangue , Antígenos CD34/sangue , Células da Medula Óssea/citologia , Movimento Celular/fisiologia , Terapia Combinada , Ecocardiografia sob Estresse , Feminino , Citometria de Fluxo , Glicoproteínas/sangue , Células-Tronco Hematopoéticas , Humanos , Antígenos Comuns de Leucócito/sangue , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/sangue , Infarto do Miocárdio/fisiopatologia , Peptídeo Natriurético Encefálico/sangue , Peptídeos/sangue , Estudos Prospectivos , EspirometriaRESUMO
In the advent of affordable photo- and soft-lithography using polydimethylsiloxane (PDMS), low cost multi-step microfabrication methods have become available to a broad scientific community today. Although these methods are frequently applied for microfluidic prototype production in academic and industrial settings, fast design iterations and rapid prototyping within a few minutes with a high degree of flexibility are nearly impossible. To reduce microfluidic concept-to-chip time and costs, a number of alternative rapid prototyping techniques have recently been introduced including CNC micromachining, 3D printing and plotting out of numeric CAD designs as well as micro-structuring of thin PDMS sheets and pressure sensitive adhesives. Although micro-structuring of pressure sensitive adhesives promises high design flexibility, rapid fabrication and simple biochip assembly, most adhesives are toxic for living biological systems. Since an appropriate bio-interface and proper biology-material interaction is key for any cell chip and organ-on-a-chip system, only a limited number of medical-grade materials are available for microfluidic prototyping. In this study, we have characterized four functional biomedical-grade pressure sensitive adhesives for rapid prototyping (e.g. less than 1 hour) applications including structuring precision, physical and optical properties as well as biocompatibilities. While similar biocompatibility was found for all four adhesives, significant differences in cutting behavior, bonding strength to glass and polymers as well as gas permeability was observed. Practical applications included stability testing of multilayered, membrane-integrated organ-on-a-chip devices under standard cell culture conditions (e.g. 2-3 weeks at 37 °C and 100% humidity) and a shear-impact up to 5 dynes/cm2. Additionally, time- and shear-dependent uptake of non-toxic fluorescently labelled nanoparticles on human endothelial cells are demonstrated using micro-structured adhesive-bonded devices. Our results show that (a) both simple and complex microdevices can be designed, fabricated and tested in less than 1 hour, (b) these microdevices are stable for weeks even under physiological shear force conditions and (c) can be used to maintain cell monolayers as well as 3D cell culture systems.
Assuntos
Dispositivos Lab-On-A-Chip , Microfluídica/instrumentação , Impressão Tridimensional/instrumentação , Adesivos/química , Materiais Biocompatíveis/química , Simulação por Computador , Dimetilpolisiloxanos/química , Células Endoteliais/efeitos dos fármacos , Desenho de Equipamento , Células Endoteliais da Veia Umbilical Humana , Humanos , Teste de Materiais , Microtecnologia , Oxigênio/química , Permeabilidade , Polímeros , Estresse Mecânico , Resistência à TraçãoRESUMO
Intensification and expansion of agricultural production since the 1970s have increased soil erosion problems in south-central Chile. Quantitative information on soil loss is needed for erosion risk assessment and to establish the effectiveness of improved land management practices. Since information from traditional sources, such as erosion plots, is limited, attention has been directed to the use of environmental radionuclides for documenting erosion rates. Cs-137 has been successfully utilised for this purpose, but only provides information on medium-term erosion rates. There is also a need to document event-related soil erosion. This paper outlines the basis for using (7)Be measurements to document short-term erosion and reports its successful use for quantifying the erosion that occurred within an arable field, as a result of a period of heavy rainfall (400mm in 27 days) occurring in May 2005. The study field had been under a no-till, no-burning system for 18 years, but immediately prior to the period of heavy rainfall the harvest residues were burnt. The erosion recorded therefore reflected both the extreme nature of the rainfall and the effects of the burning in increasing surface runoff and erosion. The sampled area corresponded to that used previously by the authors to document the medium-term erosion rates associated with both conventional tillage and the subsequent switch to a no-till system. Comparisons between the erosion documented for the period of heavy rainfall in 2005 with these medium-term erosion rates permits some tentative conclusions regarding the importance of extreme events and the impact of burning in increasing the erosion associated with the no-till system.
Assuntos
Berílio/análise , Chuva , SoloRESUMO
The transfer factor (TF) of radiocaesium from soil-to-Swiss chard (Beta vulgaris var. cicla L.) was studied in two different characteristic allophanic soils (umbric andosol and dystric fluvisol) of the Lake Region, an important agricultural region situated in central-south Chile. To investigate especially the time dependence and the effect of K-fertilisation on the TF, field experiments were conducted. Plots of 7.6 m2 were labelled with 100 kBq 134Cs m(-2) at Santa Rosa Experiment Station close to the city of Valdivia characterised by a temperate climate and high precipitation rates. The variation in time of the radiocaesium TF soil-to-Swiss chard was observed during two consecutive years after soil contamination by sequential harvests and radiocaesium analyses of the plants. The TFs showed no significant ageing effect, but a pronounced seasonal decrease with effective half-lives of about 140 and 160 days for the umbric andosol without and with K-fertilisation, respectively, and of 50 and 60 days for the dystric fluvisol without and with K-fertilisation, respectively. The effect of K-fertilisation on the absolute values of the TF was determined by the ratio between the median TF values obtained for corresponding dates without and with use of K-fertiliser. A ratio of TF(without K)/TF(with K) = 1.8 for the umbric andosol and TF(without K)/TF(with K) = 2.9 for the dystric fluvisol was obtained, indicating a reduction of the TF by applying 90 kg K ha(-1). The maximal values of the TF to chard predicted by the equation characterising the seasonal decrease of the TF at the beginning of the harvest periods are 0.19 for the umbric andosol and 0.11 for the dystric fluvisol, both values for soil treated with common K-fertilisation.
Assuntos
Beta vulgaris/metabolismo , Radioisótopos de Césio/farmacocinética , Estações do Ano , Solo/análise , Transporte Biológico , Chile , Fertilizantes , Meia-Vida , Potássio/metabolismoRESUMO
Four groups, each of 25 male and 25 female weanling rats, were given dietary levels of 0, 0.1, 0.5 and 2.5 ppm MeHgCl for 2 years. Observations were made on behaviour, growth, food intake, haematology, serum enzymes, urinalysis, microsomal liver enzymes, organ weights and histology with special reference to the nervous system, histochemistry of the kidneys and cerebellum and on tissue Hg concentrations. Significant findings included a slight growth reduction in females at 2.5 ppm, increased relative kidney weight at 2.5 ppm and histochemical changes in kidney enzymes at 2.5 ppm. No effect was seen on the nature or incidence of pathological lesions or tumours at any level. From the results obtained in the short-term, reproduction and long-term studies, the no-toxic effect level for rats appears to be between 0.1 and 0.5 ppm MeHgCl in the diet. Exposure of the Dutch population does not appear to present a health hazard at the moment because the mean intake of total Hg is still far below the intake deemed to be safe.
Assuntos
Compostos de Metilmercúrio/toxicidade , Animais , Peso Corporal/efeitos dos fármacos , Dieta , Feminino , Isoenzimas , Rim/enzimologia , L-Lactato Desidrogenase/metabolismo , Masculino , Compostos de Metilmercúrio/sangue , Compostos de Metilmercúrio/metabolismo , Microssomos Hepáticos/enzimologia , Tamanho do Órgão/efeitos dos fármacos , Ratos , Fatores de TempoRESUMO
In the range-finding test, 6 groups of 4 male and 4 female weanling rats were given dietary levels of 0, 0.1,0.5, 2.5, 12.5 and 250 ppm methylmercury chloride (MeHgCl) for 2 weeks. Signs of central nervous system toxicity, weight loss and high mortality appeared at 250 ppm but not at lower levels. No haematological changes were observed at 0.1-12.5 ppm. The relative weights of the liver in females on 2.5 and 12.5 ppm and of the kidneys in females on 12.5 ppm were significantly increased; the effects in males were less marked. Total mercury concentration in the kidneys increased proportionally with increasing dietary levels of MeHgCl. In the short-term test, 5 groups of 15 male and 10 female weanling rats were given dietary levels of 0, 0.1, 0.5, 2.5 and 25 ppm MeHgCl for 12 weeks. Toxic signs, weight loss and restricted food intake were observed at 25 ppm starting from week 9 onwards. Haematological, serum enzyme and urinalysis changes were seen at 25 ppm. Liver microsomal enzyme activity was increased non-significantly and liver glycogen was depressed at 25 ppm. Organ weight changes were evident at 25 ppm and histological changes seen in the spleen, kidneys, brain, spinal cord and peripheral nerves were confined to the 25 ppm level. Histochemical changes in kidney enzymes occured at 2.5 and 25 ppm. Hg concentrations in blood, hair, kidneys, liver and brain were higher at 12 weeks than 6 weeks and generally increased with increasing MeHgCl level in the diet.
Assuntos
Compostos de Metilmercúrio/toxicidade , Animais , Peso Corporal/efeitos dos fármacos , Dieta , Comportamento Alimentar/efeitos dos fármacos , Feminino , Glicogênio/metabolismo , Crescimento/efeitos dos fármacos , Hemoglobinas/metabolismo , Masculino , Compostos de Metilmercúrio/metabolismo , Microssomos Hepáticos/metabolismo , Tamanho do Órgão/efeitos dos fármacos , RatosRESUMO
A reproduction study over 3 generations of rats was carried out in which groups of 20 female and 10 male rats received in the diet 0, 0.1, 0.5 and 2.5 ppm MeHgCl. The parameters studied included growth, food intake, haematology, serum and urinalysis, organ weights and reproductive performance, No effect was exerted on fertility index, lactation index or on the 21-day body weights of pups but the viability index was impaired at 2.5 ppm in the F1 and F2 generations. Weight gain reductions observed at 12 weeks for the 2.5 ppm level were not accompanied by reductions in food intake. At 6 months, Fla females on 2.5 ppm showed a reduced leucocyte count whilst P males on 0.5 and 2.5 ppm showed an increase in neutrophils and a decrease in lymphocytes. The relative weights of the kidneys, heart, spleen brain and thyroid were increased at 2.5 ppm and in some cases the increases of kidney weights were inconsistently seen at the 0.1 and 0.5 ppm levels. No significant histological changes were seen at any level. In a special 7-week study involving the F3a generation, weanling rats obtained from the four different F2a groups, each comprising 20 females and 10 males, were all transferred to diets containing 25 ppm MeHgCl. Toxicity signs were evident at 7 weeks. No evidence was obtained of increased susceptibility to the toxicity of MeHgCl in successive generations.
Assuntos
Comportamento Alimentar/efeitos dos fármacos , Compostos de Metilmercúrio/toxicidade , Reprodução/efeitos dos fármacos , Anormalidades Induzidas por Medicamentos/etiologia , Animais , Comportamento Animal/efeitos dos fármacos , Peso Corporal/efeitos dos fármacos , Feminino , Masculino , Compostos de Metilmercúrio/farmacologia , Tamanho do Órgão/efeitos dos fármacos , Gravidez , Ratos , Fatores de TempoRESUMO
BACKGROUND: Adenoid cystic carcinomas (ACC) seem to have a better response to fast neutron irradiation than to photon beam therapy because of the higher relative biological effectiveness of neutron radiation. METHODS: Between 1986 and 1995, 72 patients with ACC of the salivary glands were treated in Münster with fast neutrons. The median age was 54 years. All the patients had either recurrent or macroscopic rest tumor prior to neutron therapy. The median total dose was 15.03 Gy. Median follow-up was 50 months. RESULTS: 39.1% of the patients achieved a complete remission and 48.6% a partial remission. The survival probability was 86% after one year, 73% after two years and 53% after five years. The recurrence-free survival was 83% after one year, 71% after two years and 45% after five years. CONCLUSION: Neutron beam therapy seems to have been an effective treatment in these selected patients.
Assuntos
Carcinoma Adenoide Cístico/radioterapia , Nêutrons Rápidos/uso terapêutico , Neoplasias das Glândulas Salivares/radioterapia , Adolescente , Adulto , Idoso , Carcinoma Adenoide Cístico/diagnóstico , Carcinoma Adenoide Cístico/mortalidade , Carcinoma Adenoide Cístico/patologia , Intervalo Livre de Doença , Feminino , Seguimentos , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Dosagem Radioterapêutica , Estudos Retrospectivos , Neoplasias das Glândulas Salivares/diagnóstico , Neoplasias das Glândulas Salivares/mortalidade , Neoplasias das Glândulas Salivares/patologia , Taxa de Sobrevida , Fatores de Tempo , Tomografia Computadorizada por Raios XRESUMO
A thin-layer chromatographic method is described for the analysis of aflatoxins in animal liver. Liver samples are extracted with chloroform and phosphoric acid. After filtration, an aliquot is evaporated and defatted by liquid-liquid partitioning. The extract is submitted to silica gel minicolumn cleanup and the final extract is concentrated and submitted to two-dimensional thin-layer chromatography (TLC). The identity of aflatoxins B1 and M1 is confirmed with trifluoroacetic acid (TFA) carried out on the thin-layer plate used for quantitation of these aflatoxins. The method permits the detection and confirmation of aflatoxins in liver in concentrations as low as 0.05 micrograms/kg. Average recoveries for aflatoxin M1 and aflatoxin B1 at spiking levels of 0.2 micrograms/kg were found to be 65% and 85%, respectively. With this method, 73 samples of bovine liver, 70 samples of porcine liver, and 56 samples of chicken liver taken from different slaughterhouses were investigated. In one sample of bovine liver, aflatoxins B1, B2, and M1 could be detected in concentrations of 0.10, 0.03, and 0.08 micrograms/kg, respectively.
Assuntos
Aflatoxinas/análise , Fígado/química , Aflatoxina B1 , Aflatoxina M1 , Animais , Cromatografia em Camada Fina/métodos , Indicadores e Reagentes , Solventes , Ácido TrifluoracéticoRESUMO
Whole blood and urine from 23 patients ingesting ammonium nitrate daily in amounts varying from 2 . 5-9 g were analysed for volatile N-nitrosamines. By contrast with reports in the literature N-nitrosodimethylamine and N-nitrosodiethylamine were not found in blood (limit of detection 0 . 1 micrograms/kg) but a trace of N-nitrosopyrrolidine was found in the blood of one subject. Small amounts of N-nitrosomorpholine in some blood samples and in one blank were believed to be formed during the analysis since morpholine had been added to the samples to indicate artefactual nitrosamine formation. Traces of N-nitrosodimethylamine (0 . 1 microgram/kg) were found in six of the 23 urine samples.
Assuntos
Nitratos/metabolismo , Nitrosaminas/isolamento & purificação , Adolescente , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Nitratos/administração & dosagem , Nitrosaminas/sangue , Nitrosaminas/urina , VolatilizaçãoRESUMO
AIMS AND BACKGROUND: Radiotherapy with fast neutrons offers radiobiological advantages in the treatment of hypoxic and slowly proliferating tumors. Tumors recurring in pre-irradiated areas of the head and neck usually exhibit a low radiation sensitivity that seems to promise little success for a repeated irradiation with photons. In such a situation, radiotherapy with fast neutrons may offer an alternative treatment option. To evaluate the question, the Muenster patients were retrospectively analyzed. METHODS: During the period July 1986 to January 1994, 26 patients with local-regional recurrences of pre-irradiated head and neck tumors were treated with fast neutrons at our department. RESULTS: Median survival calculated by the Kaplan-Meier method was 7.4 months. The 1-year survival probability was 29.3% and the 2-year survival probability 5.9%. The objective tumor remission (complete + partial) was 50%. A subjective improvement of symptoms was reported by 42.3% of all patients. CONCLUSIONS: Despite relatively unfavorable survival rates produced by the therapy, good remission rates and thereby a good palliative effect can be attained with a short treatment time and tolerable side effects.
Assuntos
Nêutrons Rápidos/uso terapêutico , Neoplasias de Cabeça e Pescoço/radioterapia , Recidiva Local de Neoplasia/radioterapia , Cuidados Paliativos/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Intervalo Livre de Doença , Nêutrons Rápidos/efeitos adversos , Feminino , Neoplasias de Cabeça e Pescoço/patologia , Humanos , Metástase Linfática , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Radioterapia/efeitos adversos , Radioterapia/métodos , Estudos Retrospectivos , Análise de Sobrevida , Resultado do TratamentoRESUMO
The purpose of this prospective was study to investigate the course of patients after obliteration of bleeding esophageal varices by endoscopic sclerotherapy and to outline prognostic factors. Sixty-seven patients (45 men, 22 women, mean age: 53.3 +/- 14 years) were followed for a mean of 14 +/- 8 months median = 15 months-range: 1-33 months) from the time of obliteration. Etiology of portal hypertension was portal vein thrombosis in 3 patients and cirrhosis in 64, 44 of whom (65 p. 100) were due to alcoholism (Child-Pugh's class: A: 8 p. 100, B: 42 p. 100, C: 50 p. 100). Recurrence of varices was observed in 23 patients within 1.4 to 25 months (median: 6.6 months). The recurrence rate increased in a linear fashion with time. Reobliteration was achieved in one to three sessions of sclerotherapy. More than one bleeding episodes was observed more often, before sclerotherapy (p less than 0.05) and esophageal stenosis was seen less often during treatment (p less than 0.05) than in patients without recurrence. Variceal bleeding occurred in 14 patients (21 p. 100) within 0.1 to 23 months (median = 5.6), 6 of whom (43 p. 100) died. In the subgroup of alcoholic cirrhosis, absence of withdrawal was associated with a higher risk of rebleeding (p = 0.04). Fifteen patients (22 p. 100) died within 1 to 26 months (median = 12.3). They had a higher mean age (p less than 0.01) and a lower blood fibrinogen (p less than 0.05) than survivors.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Varizes Esofágicas e Gástricas/terapia , Soluções Esclerosantes/uso terapêutico , Estenose Esofágica/induzido quimicamente , Esofagoscopia , Feminino , Hemorragia Gastrointestinal/terapia , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Recidiva , Soluções Esclerosantes/efeitos adversosRESUMO
An attempt was made to show if and to what extent the 137Cs transfer from soil to plants (grass) in forest clearings and grassland is related closely enough to different soil parameters to make it worthwhile to develop mathematical models for the prediction of transfer coefficients for certain plants and sites based solely on soil parameters. For this reason 62 soil samples from 0- to 5-cm in depth as well as from 5- to 10-cm in depth were measured for worldwide 137Cs fallout and analyzed for exchangeable potassium content, total potassium content, clay fraction, potential exchange capacity, pH value and carbon content. For both ecosystems, large variations of the transfer coefficients were observed: between 0.01 and 0.1 for grassland and 0.05 and 6 for forest clearings . Correlations, such as has been found between soil parameters, specific activities of the plants and transfer coefficients can in principle be integrated into different calculations for the estimation of radiation burden.
Assuntos
Radioisótopos de Césio/metabolismo , Plantas/metabolismo , Cinza Radioativa , Poluentes Radioativos do Solo , Poluentes do Solo , Solo/análiseRESUMO
The time dependency of nuclear test 137Cs in soil, prairie plants, and milk was observed on pastures of seven dairy farms in the 10th Region, Chile, from 1982 to 1997, without any appreciable deposition of radioactive fallout after 1983. Whereas the 137Cs concentration in the soil decreased at a rate close to that of the radionuclide's physical decay during the whole observation period, the rate of decrease of the 137Cs concentration in the prairie plants and in the milk, having been very rapid between 1982-1990, became slower between 1991-1997. The effective half-lives of the concentration in plants were found to be 5.6 y and 12 y during the first and second observation periods, respectively. Similar half-lives of 5.5 y and 13 y were found for the concentration decline in milk during each period. These data clearly demonstrate a reduction in the long-term decrease of the 137Cs plant uptake, and consequently in the decrease of the 137Cs concentration in milk, resulting from a decline of 137Cs availability for prairie plants in the Hapludand soils over the whole 15-y observation period.
Assuntos
Radioisótopos de Césio/análise , Cinza Radioativa , Poluentes Radioativos do Solo/análise , Animais , Chile , Meia-Vida , Leite/química , Plantas/químicaRESUMO
Soil, prairie plants, and milk samples were collected at 39 dairy farms in the 9th and 10th Region in Southern Chile (38 degrees 44'-41 degrees 08' S) between 1982 and 1990. 137Cs concentrations found in soil, plant, and milk samples ranged from 3.8-17.1 Bq kg-1 for soil, from < 0.3-20 Bq kg-1 dry mass for plants, and from 0.10-0.71 Bq kg-1 for milk. Cesium concentration levels resulting from soil sample measurements exhibit a close similarity with corresponding values found in soils from Central Europe before 1986. The concentration ratio prairie plants:soil ranged from 0.05-0.62, 0.52-5.0, and < 0.02-0.40 corresponding to Dystrandepts, Placandepts, and Palehumults soil groups, respectively. At seven selected dairy farms in the vicinity of Valdivia city (10th Region), soil, prairie plant, and milk samples were taken yearly during the grazing period between 1982 and 1990. Results obtained from soil samples taken after April 1986 show no significant increase of the 137Cs concentration. Concentrations in plants and milk for 137Cs decreased during the observation time. 134Cs (as an indicator of Chernobyl fallout) was not found in soil, plant, or milk samples during 1986-1990.
Assuntos
Radioisótopos de Césio/análise , Contaminação Radioativa de Alimentos/análise , Leite/química , Plantas/química , Cinza Radioativa , Poluentes Radioativos do Solo/análise , Animais , ChileRESUMO
In order to detect characteristic regional differences or temporal changes of 129I concentrations in the biosphere, thyroids from humans, grazing livestock, and herbivorous wildlife species (reindeer and roedeer) were collected in various areas of the world which are not affected by reprocessing plants. For reasons of comparison, all samples were analyzed for their 129I:127I atom ratios. Human and bovine thyroids taken from the 10th region in Southern Chile (39 degrees-41 degrees South) indicated values of the 129I:127I atom ratio between 1.1 x 10(-9) and 2.0 x 10(-9) and between 1.2 x 10(-10) and 9 x 10(-9), respectively. They showed no significant increase in the concentration of biospheric 129I in comparison with that established in the pre-nuclear age. Atom ratios found in human thyroids collected in Lower Saxony (Federal Republic of Germany), which is a region not directly affected by reprocessing plants, exhibited 129I:127I values between 8 x 10(-9) and 6 x 10(-8) from February 1988 to September 1990. Thyroid glands of reindeer and roedeer as well as heather, moss, and lichen were taken from the Vilhelmina, Heby, and Gävle communes in Sweden and analyzed for 129I and 127I. All three communes were found to be seriously contaminated by fallout from the Chernobyl accident. Highest 129I:127I atom ratios between 3.5 x 10(-7) and 1 x 10(-6) were found in the Gävle commune (approximately 150 km northwest of Stockholm) where the highest 137Cs ground deposition (70-80 kBq m-2) was measured. Two soil samples taken from Krasnaya Gora and Mirny locations in Russia (approximately 200 km northeast of Chernobyl) exhibited ratios of about 1 x 10(-6). These locations showed a 137Cs ground deposition of 370 and 1,300 kBq m-2, respectively.