Exercise Stress Test in The Assessment of Brugada Syndrome Patients

Abstract Brugada syndrome (BS) is a genetic channelopathy, clinically characterized by an increased risk of sudden cardiac death. The diagnosis requires a typical electrocardiographic pattern, and data on risk stratification are limited in the literature. The aim of this study was to conduct a review on the importance of exercise stress test (EST) in risk stratification in BS. Articles were searched in the PubMed, Scielo and Google Scholar databases. From the 200 articles retrieved, eight were included, with a total of 712 patients (95% men) aged between 35 and 60 years. Severe symptoms and ventricular arrhythmias were reported by 256 patients before the EST, with syncope being reported in 70% of cases. The reviewed articles suggest that the EST is a safe method that can help in the diagnosis and risk stratification for malignant arrhythmias in patients with BS. Potential predictors of poor prognosis were: augmentation in ST-segment elevation > 0.5 mV in V1, V2 or V3 in early recovery; J-point elevation in lead > 2mm in aVR in late recovery; heart rate reduction < 40% from maximum heart rate in late recovery and occurrence of ventricular extrasystoles in early recovery.

Capacidade Preditiva dos Parâmetros do Teste de Esforço Cardiopulmonar em Pacientes com Insuficiência Cardíaca em Terapia de Ressincronização Cardíaca / Predictive Ability of Cardiopulmonary Exercise Test Parameters in Heart Failure Patients with Cardiac Resynchronization Therapy

Resumo Fundamento Há evidências sugerindo que um corte do pico de consumo de oxigênio (pVO2) de 10ml/kg/min fornece uma estratificação de risco mais precisa em pacientes com Terapia de Ressincronização Cardíaca (TRC). Objetivo Comparar o poder prognóstico de vários parâmetros do teste cardiopulmonar de exercício (TCPE) nesta população e avaliar a capacidade discriminativa dos valores de corte de pVO2 recomendados pelas diretrizes. Métodos Avaliação prospectiva de uma série consecutiva de pacientes com insuficiência cardíaca (IC) com fração de ejeção do ventrículo esquerdo ≤40%. O desfecho primário foi um composto de morte cardíaca e transplante cardíaco urgente (TC) nos primeiros 24 meses de acompanhamento, e foi analisado por vários parâmetros do TCPE para a maior área sob a curva (AUC) no grupo TRC. Uma análise de sobrevida foi realizada para avaliar a estratificação de risco fornecida por vários pontos de corte diferentes. Valores de p < 0,05 foram considerados significativos. Resultados Um total de 450 pacientes com IC, dos quais 114 possuíam aparelho de TRC. Esses pacientes apresentaram um perfil de risco basal mais alto, mas não houve diferença em relação ao desfecho primário (13,2% vs 11,6%, p = 0,660). A pressão expiratória de dióxido de carbono no limiar anaeróbico (PETCO2AT) teve o maior valor de AUC, que foi significativamente maior do que o de pVO2 no grupo TRC (0,951 vs 0,778, p = 0,046). O valor de corte de pVO2 atualmente recomendado forneceu uma estratificação de risco precisa nesse cenário (p <0,001), e o valor de corte sugerido de 10 ml/min/kg não melhorou a discriminação de risco em pacientes com dispositivos (p = 0,772). Conclusão A PETCO2AT pode superar o poder prognóstico do pVO2 para eventos adversos em pacientes com TRC. O ponto de corte de pVO2 recomendado pelas diretrizes atuais pode estratificar precisamente o risco dessa população.

Abstract Background There is evidence suggesting that a peak oxygen uptake (pVO2) cut-off of 10ml/kg/min provides a more precise risk stratification in cardiac resynchronization therapy (CRT) patients. Objective To compare the prognostic power of several cardiopulmonary exercise testing (CPET) parameters in this population and assess the discriminative ability of the guideline-recommended pVO2cut-off values. Methods Prospective evaluation of consecutive heart failure (HF) patients with left ventricular ejection fraction ≤40%. The primary endpoint was a composite of cardiac death and urgent heart transplantation (HT) in the first 24 follow-up months, and was analysed by several CPET parameters for the highest area under the curve (AUC) in the CRT group. A survival analysis was performed to evaluate the risk stratification provided by several different cut-offs. p values <0.05 were considered significant. Results A total of 450 HF patients, of which 114 had a CRT device. These patients had a higher baseline risk profile, but there was no difference regarding the primary outcome (13.2% vs 11.6%, p =0.660). End-tidal carbon dioxide pressure at anaerobic threshold (PETCO2AT)had the highest AUC value, which was significantly higher than that of pVO2in the CRT group (0.951 vs 0.778, p =0.046). The currently recommended pVO2cut-off provided accurate risk stratification in this setting (p <0.001), and the suggested cut-off value of 10 ml/min/kg did not improve risk discrimination in device patients (p =0.772). Conclusion PETCO2ATmay outperform pVO2's prognostic power for adverse events in CRT patients. The current guideline-recommended pVO2 cut-off can precisely risk-stratify this population.

Determinantes da capacidade funcional em pacientes com doença de chagas / Determinants of functional capacity in patients with chagas disease

Resumo Fundamento: A doença de Chagas leva à redução da capacidade funcional. Entretanto, o estágio em que o comprometimento funcional é detectável permanece obscuro. Objetivos: O presente estudo teve como objetivo comparar a capacidade funcional de pacientes em diferentes estágios da doença de Chagas e de indivíduos saudáveis e verificar os determinantes do consumo de oxigênio de pico (VO2pico). Métodos: Em um estudo transversal, foram selecionados 160 indivíduos, 35 saudáveis e 125 com doença de Chagas. No grupo chagásico, 61 (49%) estavam na forma indeterminada da doença, 45 (36%) com cardiomiopatia chagásica (CC) e função cardíaca preservada e 19 (15%) com disfunção cardíaca e CC dilatada. Os dados foram analisados por meio de análise de regressão univariada e multivariada. A significância estatística foi fixada em 5%. Resultados: Pacientes na forma indeterminada da doença apresentaram capacidade funcional semelhante a indivíduos saudáveis (p> 0,05). Pacientes com ChC e função cardíaca preservada apresentaram VO2pico menor que os pacientes na forma indeterminada (p <0,05), mas apresentaram valores de VO2pico semelhantes ao ChC dilatado (p = 0,46). A idade, sexo masculino, classe funcional da NYHA, pressão arterial diastólica, razão entre a velocidade do fluxo transmitral diastólico precoce e a velocidade anular mitral diastólica precoce, a fração de ejeção do ventrículo esquerdo (FEVE) e o diâmetro diastólico final do ventrículo esquerdo foram associados à capacidade funcional. Porém, apenas idade, sexo masculino, FEVE e classe funcional da NYHA permaneceram associados ao VO2pico no modelo final (R2 ajustado = 0,60). Conclusão: Pacientes com CC apresentam menor capacidade funcional do que pacientes na forma indeterminada. FEVE, idade, sexo masculino e classe funcional da NYHA foram determinantes do VO2pico em pacientes com doença de Chagas.

Abstract Background: Chagas disease leads to reduced functional capacity. However, the stage at which functional impairment is detectable remains unclear. Objectives: The present study was addressed to compare the functional capacity of patients at different stages of Chagas disease and healthy individuals and to verify the determinants of peak oxygen uptake (VO2peak). Methods: In a cross-sectional study, 160 individuals were selected, 35 healthy and 125 with Chagas disease. In the Chagasic group, 61 (49%) were in the indeterminate form of the disease, 45 (36%) with Chagas cardiomyopathy (ChC) and preserved cardiac function and 19 (15%) with cardiac dysfunction and dilated ChC. The data were analyzed using univariate and multivariate regression analysis. Statistical significance was set at 5%. Results: Patients in the indeterminate form of disease showed similar functional capacity to healthy individuals (p>0.05). Patients with ChC and preserved cardiac function had lower VO2peak than patients in the indeterminate form (p<0.05), but showed similar VO2peak values than dilated ChC (p=0.46). The age, male sex, NYHA functional class, diastolic blood pressure, ratio of the early diastolic transmitral flow velocity to early diastolic mitral annular velocity, left ventricular ejection fraction (LVEF) and left ventricular end-diastolic diameter were associated with functional capacity. However, only age, male sex, LVEF and NYHA functional class, remained associated with VO2peak in the final model (adjusted R2=0.60). Conclusion: Patients with ChC had lower functional capacity than patients in the indeterminate form. LVEF, age, male sex and NYHA functional class were determinants with VO2peak in patients with Chagas disease.

Intensidade de Exercício durante o Teste de Caminhada de 6 Minutos em Pacientes com Doença Arterial Periférica / Exercise Intensity during 6-Minute Walk Test in Patients with Peripheral Artery Disease

Resumo Fundamento a caminhada não supervisionada em solo tem sido indicada para pacientes com doença arterial periférica (DAP) sintomática. No entanto, a magnitude do esforço exigido por essa atividade e as características dos pacientes que a praticam com mais intensidade não estão claras. Objetivos determinar se a caminhada em solo excede o limiar ventilatório (LV), um reconhecido marcador de intensidade de exercício, em pacientes com DAP sintomática. Métodos Foram recrutados 70 pacientes (61,4% do sexo masculino e com idade entre 40 e 85 anos) com DAP sintomática. Os pacientes realizaram um teste ergométrico em esteira para definir o LV. Em seguida, foram submetidos ao teste de caminhada de 6 minutos para determinar o alcance do LV durante deambulação no solo. Realizou-se regressão logística múltipla para identificar preditores de LV durante o teste de caminhada de 6 minutos, e o valor de p<0,05 foi considerado significativo para todas as análises. Resultados Ao todo, 60% dos pacientes atingiram o LV durante o teste de caminhada de 6 minutos. Mulheres (OR = 0,18 e IC95% = 0,05 a 0,64) e pacientes com mais aptidão cardiorrespiratória (OR = 0,56 e IC 95% = 0,40 a 0,77) tiveram menor probabilidade de chegar ao LV durante a caminhada em solo em comparação a homens e pacientes com menos aptidão cardiorrespiratória, respectivamente. Conclusão Mais da metade dos pacientes com DAP sintomática alcançou o LV durante o teste de caminhada de 6 minutos. Mulheres e pacientes com mais aptidão cardiorrespiratória têm menos probabilidade de chegar ao LV durante o teste de caminhada de 6 minutos, o que indica que a caminhada no solo pode ser mais intensa para esse grupo. Isso deve ser considerado ao se prescreverem exercícios de caminhada em solo para esses pacientes. (Arq Bras Cardiol. 2020; 114(3):486-492)

Abstract Background Non-supervised ground walking has been recommended for patients with symptomatic peripheral artery disease (PAD). However, the magnitude of the effort required by this activity and the characteristics of patients whose ground walking is more intense are unclear. Objectives To determine whether ground walking exceeds the ventilatory threshold (VT), a recognized marker of exercise intensity, in patients with symptomatic PAD. Methods Seventy patients (61.4% male and aged 40 to 85 years old) with symptomatic PAD were recruited. Patients performed a graded treadmill test for VT determination. Then, they were submitted to a 6-minute walk test so the achievement of VT during ground ambulation could be identified. Multiple logistic regression was conducted to identify predictors of VT achievement during the 6-minute walk test. The significance level was set at p < 0.05 for all analyses. Results Sixty percent of patients achieved VT during the 6-minute walk test. Women (OR = 0.18 and 95%CI = 0.05 to 0.64) and patients with higher cardiorespiratory fitness (OR = 0.56 and 95%CI = 0.40 to 0.77) were less likely to achieve VT during ground walking compared to men and patients with lower cardiorespiratory fitness, respectively. Conclusion More than half of patients with symptomatic PAD achieved VT during the 6-minute walk test. Women and patients with higher cardiorespiratory fitness are less likely to achieve VT during the 6-minute walk test, which indicates that ground walking may be more intense for this group. This should be considered when prescribing ground walking exercise for these patients. (Arq Bras Cardiol. 2020; 114(3):486-492)

Test-Retest Reliability of Non-Invasive Cardiac Output Measurement during Exercise in Healthy Volunteers in Daily Clinical Routine / Confiabilidade Teste-Reteste de Medição Não-Invasiva de Débito Cardíaco durante Exercício em Voluntários Saudáveis sob Condições Clínicas de Rotina

Abstract Background: Thoracic bioreactance (TB), a noninvasive method for the measurement of cardiac output (CO), shows good test-retest reliability in healthy adults examined under research and resting conditions. Objective: In this study, we evaluate the test-retest reliability of CO and cardiac power (CPO) output assessment during exercise assessed by TB in healthy adults under routine clinical conditions. Methods: 25 test persons performed a symptom-limited graded cycling test in an outpatient office on two different days separated by one week. Cardiorespiratory (power output, VO2peak) and hemodynamic parameters (heart rate, stroke volume, CO, mean arterial pressure, CPO) were measured at rest and continuously under exercise using a spiroergometric system and bioreactance cardiograph (NICOM, Cheetah Medical). Results: After 8 participants were excluded due to measurement errors (outliers), there was no systematic bias in all parameters under all conditions (effect size: 0.2-0.6). We found that all noninvasively measured CO showed acceptable test-retest-reliability (intraclass correlation coefficient: 0.59-0.98; typical error: 0.3-1.8). Moreover, peak CPO showed better reliability (intraclass correlation coefficient: 0.80-0.85; effect size: 0.9-1.1) then the TB CO, thanks only to the superior reliability of MAP (intraclass correlation coefficient: 0.59-0.98; effect size: 0.3-1.8). Conclusion: Our findings preclude the clinical use of TB in healthy subject population when outliers are not identified.

Resumo Fundamento: A biorreatância torácica (BT), um método não invasivo destinado à medição do débito cardíaco (DC), mostra boa confiabilidade teste-reteste em adultos saudáveis examinados em condições de pesquisa e repouso. Objetivo: No presente estudo, avaliamos a confiabilidade teste-reteste da avaliação do DC e trabalho cardíaco (TC) durante exercício, avaliado por BT em adultos saudáveis sob condições clínicas de rotina. Métodos: 25 indivíduos realizaram teste ergométrico gradual sintoma-limitante em ambiente ambulatorial em dois dias diferentes, com intervalo de uma semana. Parâmetros cardiorrespiratórios (trabalho cardíaco, VO2máx) e hemodinâmicos (frequência cardíaca, volume sistólico, DC, pressão arterial média, TC) foram medidos em repouso e continuamente sob exercício utilizando sistema espiroergométrico e cardiógrafo de biorreatância (NICOM, Cheetah Medical). Resultados: Após 8 participantes terem sido excluídos devido a erros de medição (outliers), não houve viés sistemático em nenhum dos parâmetros em todas as condições (tamanho do efeito: 0,2-0,6). Observamos que todos os débitos cardíacos medidos de forma não invasiva apresentaram níveis aceitáveis de confiabilidade teste-reteste (coeficiente de correlação intraclasse: 0,59-0,98; erro típico: 0,3-1,8). Além disso, TC máximo apresentou melhor confiabilidade (coeficiente de correlação intraclasse: 0,80-0,85; tamanho do efeito: 0,9-1,1), seguido do DC pela BT, graças apenas à confiabilidade superior da PAM (coeficiente de correlação intraclasse: 0,59-0,98; tamanho do efeito: 0,3-1,8). Conclusão: Nossos achados impedem o uso clínico da BT em indivíduos saudáveis quando outliers não forem identificados.

Use of adverse outcome pathways in chemical toxicity testing: potential advantages and limitations

Amid revolutionary changes in toxicity assessment brought about by increasing regulation of chemicals, adverse outcome pathways (AOPs) have emerged as a useful framework to assess adverse effect of chemicals using molecular level effect, which aid in setting environmental regulation policies. AOPs are biological maps that describe mechanisms linking molecular initiating event to adverse outcomes (AOs) at an individual level. Each AOP consists of a molecular initiating event, key events, and an AO. AOPs use molecular markers to predict endpoints currently used in risk assessment, promote alternatives to animal model-based test methods, and provide scientific explanations for the effects of chemical exposures. Moreover, AOPs enhance certainty in interpreting existing and new information. The application of AOPs in chemical toxicity testing will help shift the existing paradigm of chemical management based on apical endpoints toward active application of in silico and in vitro data.

Use of adverse outcome pathways in chemical toxicity testing: potential advantages and limitations

Amid revolutionary changes in toxicity assessment brought about by increasing regulation of chemicals, adverse outcome pathways (AOPs) have emerged as a useful framework to assess adverse effect of chemicals using molecular level effect, which aid in setting environmental regulation policies. AOPs are biological maps that describe mechanisms linking molecular initiating event to adverse outcomes (AOs) at an individual level. Each AOP consists of a molecular initiating event, key events, and an AO. AOPs use molecular markers to predict endpoints currently used in risk assessment, promote alternatives to animal model-based test methods, and provide scientific explanations for the effects of chemical exposures. Moreover, AOPs enhance certainty in interpreting existing and new information. The application of AOPs in chemical toxicity testing will help shift the existing paradigm of chemical management based on apical endpoints toward active application of in silico and in vitro data.

A review of ANO1-based calcium activated chloride channel modulators / 药学学报

Calcium-activated chloride channel (CaCC) is an anion channel, widely distributed in the human body, taking a part in cell functions including secretion, heart muscle repolarization, nerve signal transmission and several physiological activities. The anoctamin 1 (ANO1) protein is the molecular basis of CaCC and the modification of ANO1 protein will produce a variety of pharmacological effects, such as analgesia, treating dysentery and asthma, even tumor proliferation and migration inhibition. In the past decade, many methods in screening of ANO1 regulators have been developed. Although a series of the ANO1-based CaCC regulatory molecules have been identified, the pharmacological effects of these molecules are not consistent. In this review, we introduce ANO1 protein regulators from many aspects including bio-test methods, structure-activity relationships, and the potential applications.

Seed quality test methods of Marsdenia tenacissima / 中草药

Objective: To optimize the testing methods for seed quality of Marsdenia tenacissima, and provide basis for establishing seed quality standard of M. tenacissima. Methods: The seed quality of M. tenacissima from different producing areas was measured based on the International Seed Testing Protocol made up by ISTA and Rules for Agricultural Seed Testing issued by China. Results: The samples weight of M. tenacissima were at least 900 g for purity analysis and were at least 90 g for testing. The 1 000-seed weight was determined by 500-seed method, and the water content was carried out by higher temperature (133 ± 2)℃ for 6 h. After soaking in water for 24 h, M. tenacissima seeds were cultured in wet sand at 30℃ for 1-8 d under illumination for germination testing. Seed viability was tested by TTC method in 35℃ for 3 h. Conclusion: The seed testing methods for quality items of M. tenacissima have been initially established.

Study on seed quality test and quality standard of Lonicera macranthoides / 中国中药杂志

Referring to the rules for agricultural seed testing (GB/T 3543-1995) issued by China, the test of sampling, purity, thousand seed weight, moisture, viability, relative conductivity and germination rate had been studied for seed quality test methods of Lonicera macranthoides. The seed quality from 38 different collection areas was measured to establish quality classification standard by K-means clustering. The results showed that at least 7.5 g seeds should be sampled, and passed 20-mesh sieve for purity analysis.The 500-seed method used to measure thousand seed weight. The moisture was determined by crushed seeds dried in high temperature (130±2) ℃ for 3 h.The viability determined by 25 ℃ 0.1% TTC stained 5h in dark. 1.0 g seeds soaked in 50 ml ultra pure water in 25 ℃ for 12 hours to determine the relative conductivity. The seed by 4 ℃stratification for 80 days were cultured on paper at 15 ℃. Quality of the seeds from different areas was divided into three grades. The primary seed quality classification standard was established.The I grade and II grade were recommend use in production.

Testing methods for seed quality of Bletilla striata / 中国中药杂志

In order to provide a basis for establishing seed testing rules and seed quality standard of Bletilla striata, the seed quality of B.striata from different producing area was measured referring to the Rules for Agricultural Seed Testing(GB/T 3543-1995).The results showed that the seeds of B.striata passed through 20-mesh sieve for purity analysis.The weight of seeds was measured by 1000-seed method and the water content was measured at the higher temperature (133±2) ℃ for 3 hours.The seeds were cultured on the wet filter paper at 30 ℃ for 4-20 days in light for germination testing.The method of testing seed viability was that seeds were dipped into 1% TTC solution for 7 hours at temperature of 40 ℃.

Comparison between the 6-minute walk tests performed in patients with chronic obstructive pulmonary disease at different altitudes / Comparação entre os testes de caminhada de 6 minutos realizados em pacientes com doença pulmonar obstrutiva crônica em diferentes altitudes

Objective To evaluate the influence of the altitude on the 6-minute walking test in patients with moderate to severe pulmonary disease. Methods Twenty-nine patients performed the 6-minute walk test at a pulmonary rehabilitation clinic in Santo André (above sea level), in São Paulo State, and at the Enseada Beach, in Guarujá (at sea level), also in São Paulo State. Of these 29 patients, 8 did the test both on hard sand and on asphalt to analyze if there were differences in performance during the tests. Data such as heart rate, oxygen saturation, test distance, and Borg scale were compared. Results We found no statistical difference in relation to oxygen saturation at rest before the beginning of the walking test in Santo André 94.67±2.26% and at sea level 95.56±2% (p=0.71). The minimum saturation measured during the test was 87.27±6.54% in Santo André and 89.10±5.41% in Guarujá (p=0.098). There were no differences in the performed distance between the different kinds of terrains; the distance on sand was 387.75±5.02m and on asphalt it was 375.00±6.54m (p=0.654). Regarding oxygen saturation during walking, the pulse oximetry on sand was 95.12±1.80% and on asphalt it was 96.87±1.64% (p=1.05). Conclusion Altitude did not affect the performance of the walking test in patients with moderate to severe pulmonary disease and the results were similar in both cases, on sand and on asphalt. .

Objetivo Avaliar a influência da altitude no teste de caminhada de 6 minutos em pacientes com doença pulmonar moderada a grave. Métodos Vinte e nove pacientes realizaram o teste de caminhada de 6 minutos em um ambulatório de reabilitação pulmonar, na cidade de Santo André (acima do nível do mar), em São Paulo, e na praia da Enseada no Guarujá (ao nível do mar), também em São Paulo. Destes, oito pacientes realizaram tanto na areia batida como no asfalto, para avaliar a existência de alguma alteração no desempenho durante o teste. Dados como frequência cardíaca, saturação de oxigênio, distância do teste e escala de Borg foram comparados. Resultados Não encontramos diferença estatística em relação à saturação de oxigênio em repouso antes do início do teste de caminhada em Santo André 94,67±2,26% e ao nível do mar 95,56±2% (p=0,71). A saturação mínima obtida durante os testes foi de 87,27±6,54%, em Santo André, e de 89,10±5,41%, no Guarujá (p=0,098). Não houve diferença na distância percorrida e nos diferentes tipos de piso; a distância na areia foi de 387,75±5,02m e 375,00±40,88m no asfalto (p=0,654). Quanto à saturação durante a caminhada, a oximetria de pulso na areia foi de 95,12±1,80% e no asfalto foi de 96,87±1,64% (p=1,05), ou seja, o teste foi reprodutível em ambos os solos. Conclusão A altitude não influenciou o desempenho do teste de caminhada realizado por pacientes com doença pulmonar moderada a grave, sendo reprodutível tanto acima quanto ao nível do mar, mesmo ...

Research progress on Pasteurella pneumotropica / 中国实验动物学报

Pasteurella pneumotropica is an opportunistic and zoonotic pathogen .It mainly infects rodents , especial-ly immunodeficient or immunosuppressied animals , and causes inflammation and abscesses .It is one of the highest positive rate infection pathogens in laboratory animals .The contamination and asymptomatic infections of Infection of P.pneumo-tropica could significantly interfere in vary experiments .This review will deal with P.pneumotropica epidemiology, detection and identification methods , molecular typing and control and so on .

Glucose metabolism in preterm infants and its test / 临床儿科杂志

Because of their physiological and anatomical immaturity, premature infants are prone to disorders of glucose metabolism. In the ifrst week after birth, infants have the greater risk of abnormal glucose metabolism. Compared with term infants, the glucose/insulin homeostasis of preterm infants is very different. This article reviewed the characteristics of glycometabolism in premature infant and the methods of glucose test.

A trial of competition-oriented test methods in histology and embryologytest / 中华医学教育探索杂志

The examination of Histology and Embryology was reformed by trying competition-oriented test based on an exam system which is supported by attitude assessment and achievement in learning process.The students welcome the system for its advantages such as the original and various forms,its inspiration of enthusiasm and innovation and its humanism.The system contained processional assessment and final assessment as well.Yet the practiser should increase the rate of written examination to keep the fairness.

Métodos de extração de fósforo e potássio no solo sob sistema plantio direto / Soil phosphorus and potassium extractant in soils under no tillage

A análise de fósforo e potássio no solo, nos Estados do Rio Grande do Sul e de Santa Catarina, é realizada com a solução de Mehlich-1, e os estudos de seleção de métodos de análise para esses elementos foram feitos apenas para o sistema de cultivo convencional. Neste trabalho, a solução de Mehlich-1 foi comparada com a solução de Mehlich-3 e com o método da resina de troca iônica para análise de fósforo e potássio, em solos sob plantio direto, com experimentos de resposta das culturas à adubação fosfatada e potássica instalados no Rio Grande do Sul. As quantidades de fósforo extraídas pelos métodos da resina e Mehlich-3 foram maiores com a solução de Mehlich-1, independentemente da profundidade de amostragem. As quantidades de fósforo extraídas pelos métodos apresentaram alto grau de associação entre si. Para o potássio as quantidades extraídas foram semelhantes entre as metodologias estudadas, com alto grau de associação entre si, independentemente da profundidade de amostragem. As metodologias estudadas são eficientes na extração de fósforo e potássio no solo, em sistema plantio direto. Porém, devido às menores quantidades de P extraído pela solução de Mehlich-1, os erros em laboratório podem ser maiores pela menor amplitude de extração.

The current soil test method used to evaluate soil phosphorus and potassium available to the plants in soils from Rio Grande do Sul e Santa Catarina state is the Mehlich-1 solution. The soil test methods studies for these nutrients were conducted based on the conventional soil tillage. The aim of this work was to compare the soil phosphorus and potassium amounts extracted by the Mehlich-1 solution and the nutrients amounts extracted by the Mehlich-3 solution, and resin membrane in soils from the Rio Grande do Sul state, under no tillage soil system and nutrients crop response. The phosphorus amounts extracted by the resin method and by the Mehlich-3 solution were higher than that those extracted by the Mehlich-1 solution in both of them sampling depth. The correlation coefficients among the phosphorus amounts extracted by the methods were high association degree. The potassium amounts extracted by the methods were similar, and the correlation coefficients among the potassium amounts extracted by the methods were high association degree in all soil sampling depth. The soil testing methods that have studied in this work are efficient for soil phosphorus and potassium extraction in soils under no tillage; however, the lowest soil phosphorus amounts extracted by the Mehlich-1 solution, increase the laboratory errors.

Phenotypic detection and occurrence of extended-spectrum beta-lactamases in clinical isolates of Klebsiella pneumoniae and Escherichia coli at a tertiary Hospital in Trinidad & Tobago

The incidence and distribution of ESBL producing microorganisms such as E. coli and K. pneumoniae have been demonstrated and varies in different health care facilities and as well as other countries This study was carried out to determine the frequency of occurrence and the antimicrobial susceptibility pattern of ESBL producing E. coli and K. pneumoniae species from clinical isolates at a tertiary hospital in Trinidad & Tobago. Standard microbiological procedures and automated MicroScan System was used to identify, screen for putative ESBL production and determine antimicrobial susceptibility of 1,118 clinical isolates of Enterobacteriaceae species at the microbiology laboratory of the Eric Williams Medical Science Complex, Trinidad & Tobago over a 36 months period. All ESBL producing isolates flagged by the automated system were further confirmed by E-test method. The E-test confirmed a 15.2 percent ESBL rate among the K. pneumoniae isolates and 9.3 percent among the E. coli isolates. There was also a 1.8 percent rate of ESBL production in K. pneumoniae and 0.2 percent in E. coli isolates from specimens received from community health facilities into the laboratory. Isolates recovered from the intensive care unit of the hospital had 2.1 percent E. coli and 8.2 percent K. pneumoniae ESBL producers. Although all ESBL positive isolates were completely susceptible to imipenem and meropenem; and all positive K. pneumoniae isolates were susceptible to amikacin, there was a low susceptibility of ESBL positive E. coli to the aminoglycosides. However, susceptibility of these ESBL producing isolates to the fluoroquinolones varied. There is a high rate of ESBL production among isolates of E. coli and K. pneumoniae at this hospital that is linked to the extensive inappropriate use of third generation cephalosporins in the country. Further molecular studies are needed to characterize the types of these ESBL prevailing in the country.