RESUMO
Acremonium strictum Elicitor Subtilisin (AsES) is a fungal elicitor that activates innate immunity, conferring disease resistance in strawberry (Fragaria × ananassa Duch.), Arabidopsis and other plant species. The aim of the present work was to evaluate the involvement of the ethylene (ET) signalling pathway in AsES-mediated immune response in strawberry. Ethylene production and expression of the genes responsible for ET synthesis, perception and response were measured after AsES treatment. ROS (H2 O2 ) accumulation and immunity induced by AsES were studied after ET perception was blocked by 1-methylcyclopropene (1-MCP). Biochemical and molecular results showed that AsES induced a marked increase in local and systemic biosynthesis of ET, both in a biphasic manner. Blocking of ET perception by 1-MCP prior to AsES induction reduced production of ROS (H2 O2 ) and prevented AsES from eliciting defence against fungal pathogens having different lifestyles, such as Botrytis cinerea (necrotrophic) and Colletotrichum acutatum (hemibiotrophic). These findings contribute to elucidate the mode of action of the novel elicitor subtilase, AsES, specifically regarding the role of ET signalling in the activation of plant innate immunity, in addition to the multitude of processes regulated by ET in plants.
Assuntos
Etilenos , Fragaria , Transdução de Sinais , Subtilisina , Etilenos/metabolismo , Fragaria/efeitos dos fármacos , Fragaria/imunologia , Fragaria/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Hypocreales/química , Transdução de Sinais/efeitos dos fármacos , Subtilisina/farmacologiaRESUMO
TITLE: Hemicerebelitis por chikungunya asociado a estado epiléptico refractario en edad pediátrica.
Assuntos
Doenças Cerebelares/etiologia , Febre de Chikungunya/complicações , Estado Epiléptico/etiologia , Doença Aguda , Anticorpos Antivirais/sangue , Anticorpos Antivirais/líquido cefalorraquidiano , Anticonvulsivantes/uso terapêutico , Transtorno do Deficit de Atenção com Hiperatividade/etiologia , Transtornos de Deficit da Atenção e do Comportamento Disruptivo/etiologia , Dano Encefálico Crônico/etiologia , Doenças Cerebelares/diagnóstico por imagem , Febre de Chikungunya/sangue , Febre de Chikungunya/líquido cefalorraquidiano , Vírus Chikungunya/imunologia , Pré-Escolar , Resistência a Medicamentos , Disartria/etiologia , Humanos , Imunoglobulina M/sangue , Imunoglobulina M/líquido cefalorraquidiano , Imageamento por Ressonância Magnética , Masculino , Neuroimagem , Paresia/etiologia , Fenobarbital/uso terapêutico , Estado Epiléptico/tratamento farmacológicoRESUMO
There are very few studies which have considered perception temporality when relating perceived intensity and hedonic responses in relation to body mass index (BMI; kg/cm2). The aim of the present study was to determine the relationship between BMI with the dynamic perception and liking of bitter tasting solutions. For this purpose, two different categories of bitter products were applied: 6-n-propilthiouracil (PROP) solutions (0.010, 0.032 and 0.060â¯mmol/L) and commercial beverages (coffee, yerba mate infusion and grapefruit juice). The proposed methodology to evaluate perception and hedonic response was based on the measurement of reaction-time (R-T) and multiple-sip time-intensity (T-I) registers in people with a high BMI (25â¯<â¯BMIâ¯<â¯30; overweight group) and a normal BMI (<25; normal-weight control group). The multiple-sip evaluation to describe perception of PROP solutions and liking of beverages was used as a more ecologically valid laboratory methodology to simulate a situation of usual consumption. In this sense, working with a multiple-sip design helped confirm that bitter taste has a cumulative effect since in every case the sip effect was significant when evaluating the maximum intensity; this effect was more important as the bitterness increased. Regarding the body weight group comparisons, the normal BMI group perceived bitter taste more intensely and the time to react to it was shorter (faster reaction) for both PROP solutions and the three beverages. Interestingly, even though the high BMI group rated the bitter taste as less intense, they had a lower level of acceptance than normal BMI. This result suggests that the hedonic rather than the sensory component might be playing a crucial role in the perception of bitter taste in individuals with high BMI.
Assuntos
Índice de Massa Corporal , Preferências Alimentares , Obesidade/parasitologia , Tempo de Reação , Percepção Gustatória , Paladar , Adolescente , Adulto , Café , Feminino , Sucos de Frutas e Vegetais , Humanos , Ilex paraguariensis , Masculino , Pessoa de Meia-Idade , Obesidade/fisiopatologia , Filosofia , Propiltiouracila/administração & dosagem , Fatores de Tempo , Adulto JovemRESUMO
Induced systemic resistance (ISR) is one of the indirect mechanisms of growth promotion exerted by plant growth-promoting bacteria, and can be mediated by ethylene (ET). We assessed ET production and the expression of related genes in the Azospirillum-strawberry plant interaction. Ethylene production was evaluated by gas chromatography in plants inoculated or not with A. brasilense REC3. Also, plants were treated with AgNO3 , an inhibitor of ET biosynthesis; with 1-aminocyclopropane-1-carboxylic acid (ACC), a precursor of ET biosynthesis; and with indole acetic acid (IAA). Plant dry biomass and the growth index were determined to assess the growth-promoting effect of A. brasilense REC3 in strawberry plants. Quantitative real time PCR (qRT-PCR) was performed to analyse relative expression of the genes Faetr1, Faers1 and Faein4, which encode ET receptors; Factr1 and Faein2, involved in the ET signalling pathway; Faacs1 encoding ACC synthase; Faaco1 encoding ACC oxidase; and Faaux1 and Faami1 for IAA synthesis enzymes. Results showed that ET acts as a rapid and transient signal in the first 12 h post-treatment. A. brasilense REC3-inoculated plants had a significantly higher growth index compared to control plants. Modulation of the genes Faetr1, Faers1, Faein4, Factr1, Faein2 and Faaco1 indicated activation of ET synthesis and signalling pathways. The up-regulation of Faaux1 and Faami1 involved in IAA synthesis suggested that inoculation with A. brasilense REC3 induces production of this auxin, modulating ET signalling. Ethylene production and up-regulation of genes associated with ET signalling in strawberry plants inoculated with A. brasilense REC3 support the priming activation characteristic of ISR. This type of resistance and the activation of systemic acquired resistance previously observed in this interaction indicate that both are present in strawberry plants, could act synergistically and increase protection against pathogens.
Assuntos
Azospirillum brasilense/metabolismo , Etilenos/metabolismo , Fragaria/microbiologia , Aminoácidos Cíclicos/farmacologia , Biomassa , Etilenos/antagonistas & inibidores , Fragaria/crescimento & desenvolvimento , Fragaria/metabolismo , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Ácidos Indolacéticos/farmacologia , Proteínas de Plantas/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Receptores de Superfície Celular/metabolismo , Nitrato de Prata/farmacologiaRESUMO
K-12 Escherichia coli cells grown in static media containing a critical phosphate (Pi) concentration ≥25 mM maintained a high polyphosphate (polyP) level in stationary phase, impairing biofilm formation, a phenomenon that is triggered by polyP degradation. Pi concentration in human urine fluctuates according to health state. Here, the influence of environmental Pi concentration on the occurrence of virulence traits in uropathogenic E. coli (UPEC) isolated from acute prostatitis patients was evaluated. After a first screening, 3 isolates were selected according to differential biofilm formation profiles depending on media Pi concentration. For each isolate, biofilm positive and negative conditions were established. Regardless of the isolate, biofilm formation capacity was accompanied with curli and cellulose production and expression of some key virulence factors associated with adhesion. When the selected isolates were grown in their non-biofilm-forming condition, low concentrations of nalidixic acid and ciprofloxacin induced biofilm formation. Interestingly, similar to laboratory strains, polyP degradation induced biofilm formation in the selected isolates. Data demonstrated the complexity of UPEC responses to environmental Pi and the importance of polyP metabolism in the virulence of clinical isolates.
Assuntos
Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Infecções por Escherichia coli/microbiologia , Fosfatos/metabolismo , Prostatite/microbiologia , Escherichia coli Uropatogênica/efeitos dos fármacos , Escherichia coli Uropatogênica/fisiologia , Adulto , Idoso , Antibacterianos/metabolismo , Proteínas de Bactérias/metabolismo , Celulose/metabolismo , Ciprofloxacina/metabolismo , Humanos , Masculino , Pessoa de Meia-Idade , Ácido Nalidíxico/metabolismo , Fenótipo , Escherichia coli Uropatogênica/isolamento & purificação , Virulência/efeitos dos fármacos , Fatores de Virulência/metabolismoRESUMO
The plant growth-promoting strain REC3 of Azospirillum brasilense, isolated from strawberry roots, prompts growth promotion and systemic protection against anthracnose disease in this crop. Hence, we hypothesised that A. brasilense REC3 can induce different physiological, structural and molecular responses in strawberry plants. Therefore, the aim of this work was to study these traits activated in Azospirillum-colonised strawberry plants, which have not been assessed until now. Healthy, in vitro micropropagated plants were root-inoculated with REC3 under hydroponic conditions; root and leaf tissues were sampled at different times, and oxidative burst, phenolic compound content, malondialdehyde (MDA) concentration, callose deposition, cell wall fortification and gene expression were evaluated. Azospirillum inoculation enhanced levels of soluble phenolic compounds after 12 h post-inoculation (hpi), while amounts of cell wall bound phenolics were similar in inoculated and control plants. Other early responses activated by REC3 (at 24 hpi) were a decline of lipid peroxidation and up-regulation of strawberry genes involved in defence (FaPR1), bacterial recognition (FaFLS2) and H2O2 depuration (FaCAT and FaAPXc). The last may explain the apparent absence of oxidative burst in leaves after bacterial inoculation. Also, REC3 inoculation induced delayed structural responses such as callose deposition and cell wall fortification (at 72 hpi). Results showed that A. brasilense REC3 is capable of exerting beneficial effects on strawberry plants, reinforcing their physiological and cellular characteristics, which in turns contribute to improve plant performance.
Assuntos
Azospirillum brasilense , Biomassa , Resistência à Doença , Fragaria/microbiologia , Expressão Gênica , Peroxidação de Lipídeos , Fenóis/metabolismo , Parede Celular/metabolismo , Resistência à Doença/genética , Fragaria/crescimento & desenvolvimento , Fragaria/fisiologia , Genes de Plantas , Glucanos/metabolismo , Peróxido de Hidrogênio/metabolismo , Malondialdeído/metabolismo , Dados de Sequência Molecular , Oxirredução , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Simbiose , Regulação para CimaRESUMO
Apple consumers' expectations in Argentina and France were studied by comment analysis of open-ended questions. In an on-line survey consumers stated: attributes which defined quality in an apple; visual, flavor and texture characteristics they liked/did not like to find in an apple. Influence of country, consumption frequency and cultivar knowledge were analyzed by contingency tables, Chi-square per cell tests and Multiple Factor Analysis. Consumers' quality expectations were not the same in both countries. Argentineans and French consumers agreed that quality apples should be juicy (most used term in both countries), tasty, firm and fresh. However, for Argentineans quality was more related to visual characteristics, whereas for French it was driven by flavor. Argentineans used more words but French were more specific, particularly for flavour description. Moreover, frequency of consumption, varieties knowledge and the number of terms given were highly related. Frequent consumers knew more varieties and were more prolific in relation to flavour. Less frequent consumers knew fewer apple varieties and gave more words in the visual category. The use of comment analysis allowed identifying the terms that consumers used in their day to day life to describe apples, finding separately likes and dislikes, in spite of the different languages.
Assuntos
Comportamento do Consumidor , Comparação Transcultural , Preferências Alimentares , Qualidade dos Alimentos , Frutas , Malus , Adolescente , Adulto , Idoso , Argentina , Coleta de Dados , Feminino , França , Humanos , Idioma , Masculino , Pessoa de Meia-Idade , Especificidade da Espécie , Inquéritos e Questionários , Paladar , Terminologia como Assunto , Visão Ocular , Adulto JovemRESUMO
Desde 1987 se describieron diferentes formas clínicas de enfermedad periodontal y gingivitis en pacientes VIH/SIDA. OBJETIVO: Determinar la presencia de enfermedad periodontal en mujeres VIH/SIDA que acudieron al Centro de Atención a Pacientes con Enfermedades Infectocontagiosas (CAPEI/UCV) durante el periodo 2008-2010. MATERIALES Y METODOS: Estudio prospectivo y transversal de 55 mujeres VIH/SIDA, entre 17-57 años de edad, todas bajo terapia antirretroviral, previo consentimiento informado, se evaluaron clínicamente. Se establecieron rangos inmunológicos de acuerdo al valor en sangre de CD4 por mm 3: sin inmunodeficiencia 500 cel/mm3, moderada: 200-499 cel/mm 3 severa:< 200 cel/mm 3. A cada paciente se le aplicó el índice periodontal de Russell (IP-R). Se consideraron los valores 1 y 2 como gingivitis, y 6-8 como periodontitis. RESULTADOS: De acuerdo al status inmunológico 10 (1,8%) sin inmunosupresión, 15 (27,8%) inmunosupresión moderada y 30 (54,4 %) con inmunosupresión severa. El valor 6 del IP-R se observó en 25 mujeres (43,6 %), seguido del valor 8 en 19 mujeres (34,5 %), y 11 ( 20 %) valor 2. Se apreció una media de 4,36 para las mujeres sin inmunosupresión; inmunosupresión moderada un discreto aumento a 4,71; inmunosupresión severa, se observó la máxima expresión numérica de 5,47. El análisis de varianza demostró una dependencia o asociación estadísticamente significativa (p < 0,05). CONCLUSIÓN: Se observó una fuerte asociación entre el deterioro del sistema inmune y el estado periodontal de las mujeres estudiadas
Since 1987 were described different clinical forms of periodontal disease and gingivitis in HIV/AIDS patients. OBJECTIVE: To determine the presence of periodontal disease in HIV/AIDS women who attended Centro de Atención a Pacientes con Enfermedades Infectocontagiosas de la Universidad Central de Venezuela (CAPEI/UCV) during the period 2008-2010. MATERIALS AND METHODS: Prospective cross-sectional study of 55 women HIV/AIDS among 17-57 years of age, all under prior informed consent, antiretroviral therapy were evaluated clinically. Settled immunological ranges according to the value in of CD4 blood by 3 mm: without immunodeficiency 500 cel/mm3, mild: 200-499 cel/mm 3 severe: 200 cel/mm 3. Periodontal index of Russell (IP-R) was applied to each patient. We considered the values 1 and 2 as gingivitis and periodontitis 6-8. RESULTS: According to the status immune 10 (1.8%) without immunosuppression, 15 (27.8%) immunosuppression moderate and 30 (54.4%) with severe immunosuppression. The 6 IP-r value was observed in 25 women (43.6%), followed by the value 8 19 women (34.5%), and 11 (20%) value 2. Will appreciate an average of 4.36 for women without immunosuppression; immunosuppression moderate discreet increased to 4,71; severe immunosuppression, note the maximum numerical expression of 5.47. Analysis of variance showed a unit or statistically significant Association (p 0,05). CONCLUSION: There was a strong association between the deterioration of the immune system and the periodontal status of the women studied
Assuntos
Humanos , Feminino , Síndrome da Imunodeficiência Adquirida , HIV , Doenças Periodontais , Mulheres , OdontologiaRESUMO
INTRODUCTION: Guillain-Barre syndrome (GBS) is an acute polyradiculoneuropathy with, in most cases, an autoimmune aetiology. It manifests as a flaccid motor paralysis, of a distal ascending type, accompanied by areflexia with or without sensory alterations. AIM: To determine the clinical and therapeutic epidemiological profile of patients diagnosed as suffering from GBS who were attended at the Benjamin Bloom Children's Hospital in El Salvador, between 1st January 1997 and 31st December 2004. PATIENTS AND METHODS: We performed an observation-based, descriptive, cross-sectional study that included 414 cases. The following data were evaluated: age distribution, sex, age, history of infections, clinical manifestations, results of the lumbar puncture, electrophysiological studies and treatment that was received. RESULTS: A predominance of males was observed, together with a more frequent presentation in school-age children. The number of cases increased in the third quarter of each of the years included in the study. The most prevalent event in the history of infections was acute respiratory infection. And the most frequent clinical presentation was ascending weakness. Albuminocytological dissociation was detected in 88% of patients who had undergone lumbar puncture. Acute inflammatory demyelinating polyneuropathy predominated in 88.3% of cases. Sixty per cent of patients had to be admitted to the intensive care unit. In most cases treatment consisted in intravenous administration of immunoglobulin. Complications occurred in 30.5% of cases and the mortality rate was 2.9%. CONCLUSIONS: GBS occurs predominantly in the rainiest season of the year, which is related to an increase in the number of infections in the upper respiratory tract and gastroenteric infections that give rise to a predisposition to present secular outbreaks of the disease.
Assuntos
Síndrome de Guillain-Barré/epidemiologia , Síndrome de Guillain-Barré/fisiopatologia , Hospitais Pediátricos , Adulto , Criança , Pré-Escolar , Estudos Transversais , El Salvador/epidemiologia , Feminino , Síndrome de Guillain-Barré/diagnóstico , Síndrome de Guillain-Barré/terapia , Humanos , Masculino , Prognóstico , Chuva , Estações do AnoRESUMO
A review of the dynamic properties of nanostructured ferromagnetic materials at microwave frequencies (1-40 GHz) is presented. Since some confusion has recently appeared between giant magnetoimpedance (GMI) and ferromagnetic resonance (FMR), a detailed analysis is made in order to establish their differences. A brief review of a novel microwave absorption mode, the low-field microwave absorption (LFA) is then presented, together with a discussion about its similarities with GMI. Recent results on high-frequency measurements on nanogranular thin films and FMR in nanowire arrays are finally addressed.
RESUMO
Degenerate oligonucleotide primers, designed based on conserved regions of several serine-threonine kinases (STK) previously cloned in tomato and Arabidopsis, were used to isolate STK candidates in wild and cultivated strawberries. Seven distinct classes of STKs were identified from three related wild species, i.e., Fragaria vesca, Fragaria chiloensis, and Potentilla tucumanensis, and seven different Fragaria x ananassa cultivars. Alignment of the deduced amino acid sequences and the Pto R protein from tomato revealed the presence of characteristic subdomains and conservation of the plant STK consensus and other residues that are crucial for Pto function. Based on identity scores and clustering in phylogenetic trees, five groups were recognized as Pto-like kinases. Strawberry Pto-like clones presented sequences that were clearly identified as the activation segments contained in the Pto, and some of them showed residues previously identified as being required for binding to AvrPto. Some of the non-Pto-like kinases presented a high degree of identity and grouped together with B-lectin receptor kinases that are also involved in disease resistance. Statistical studies carried out to evaluate departure from the neutral theory and nonsynonymous/synonymous substitutions suggest that the evolution of STK-encoding sequences in strawberries is subjected mainly to a purifying selection process. These results represent the first report of Pto-like STKs in strawberry.
Assuntos
Produtos Agrícolas/genética , Fragaria/enzimologia , Fragaria/genética , Variação Genética/genética , Imunidade Inata/genética , Doenças das Plantas/genética , Proteínas Serina-Treonina Quinases/genética , Sequência de Aminoácidos , Sequência Conservada , Produtos Agrícolas/enzimologia , DNA de Plantas/genética , DNA de Plantas/isolamento & purificação , Evolução Molecular , Dados de Sequência Molecular , Filogenia , Proteínas Serina-Treonina Quinases/metabolismo , Alinhamento de SequênciaRESUMO
In this work, a simplified method is used to estimate the growth of Staphylococcus aureus in a pasteurized meat product left for several hours at environmental temperatures (diurnal time) in warm climates of different cities in Argentina. Hourly temperature data for a warm January (the hottest month of the year) day, and literature data on the kinetics of S. aureus growth inoculated in a pasteurized meat product were used for calculations. As shown by results, if a cooked meat product is left exposed to environmental temperature at diurnal time, predictions made when using a constant temperature value (i.e. average daily) may not be accurate. Growth estimations in contaminated food left under ambient conditions during diurnal time, should consider the changing environmental temperature for correct results.
En este trabajo se utiliza un método simplificado para predecir el crecimiento de Staphylococcus aureus en un producto cárnico pasteurizado dejado por varias horas a temperatura ambiente diurna en zonas de clima cálido. En la predicción, se utilizaron datos de la temperatura horaria para un día caluroso típico de enero (mes más caliente del año) en varias ciudades de la Argentina y datos de la literatura sobre tiempos de generación y tiempo lag de la bacteria inoculada en un producto cárnico pasteurizado. Los resultados indicaron que cuando el producto se deja a temperatura ambiente diurna durante varias horas, no se debe utilizar para la predicción un valor de temperatura promedio (ej.: temperatura media diaria), sino que hay que tener en cuenta la evolución de este parámetro a lo largo del período considerado.
Assuntos
Animais , Bovinos , Produtos da Carne/microbiologia , Staphylococcus aureus/crescimento & desenvolvimento , Temperatura , Altitude , Argentina , Clima , Culinária , Conservação de Alimentos , Modelos Biológicos , Saúde da População UrbanaRESUMO
In this work, a simplified method is used to estimate the growth of Staphylococcus aureus in a pasteurized meat product left for several hours at environmental temperatures (diurnal time) in warm climates of different cities in Argentina. Hourly temperature data for a warm January (the hottest month of the year) day, and literature data on the kinetics of S. aureus growth inoculated in a pasteurized meat product were used for calculations. As shown by results, if a cooked meat product is left exposed to environmental temperature at diurnal time, predictions made when using a constant temperature value (i.e. average daily) may not be accurate. Growth estimations in contaminated food left under ambient conditions during diurnal time, should consider the changing environmental temperature for correct results.
Assuntos
Produtos da Carne/microbiologia , Staphylococcus aureus/crescimento & desenvolvimento , Temperatura , Altitude , Animais , Argentina , Bovinos , Clima , Culinária , Conservação de Alimentos , Modelos Biológicos , Saúde da População UrbanaAssuntos
Humanos , Trombose Venosa , Polimorfismo Genético , Prevalência , Hipotireoidismo , Hipertireoidismo , TireoiditeAssuntos
Humanos , Polimorfismo Genético , Trombose Venosa , Hipertireoidismo , Hipotireoidismo , Prevalência , TireoiditeRESUMO
One-step room-temperature synthesis of nanocrystalline Mn3O4 hausmannite, without heating posttreatment, was carried out from a simple dissolution of manganese(II) acetate in a mixture of N,N'-dimethylformamide (DMF) and water. Homogeneous nanocrystals like rods were obtained, with an average width and length of 6.6+/-1.2 nm and 17.4+/-4.1 nm, respectively, and a preferential growth along the 001 direction. Magnetization measurements on a powdered sample showed ferrimagnetic behavior at low temperatures. Under zero-field cooling (ZFC) measurement at 100 Oe, the observed blocking temperature (T(B)) was 37 K.
RESUMO
The preparation of nanostructures using porous anodic aluminum oxide (AAO) as templates involves the introduction of dissolved materials into the pores of the membranes; one way to determine which materials are preferred to fill the pores involves the measurement of the contact angles (theta) of different solvents or test liquids on the AAOs. Thus, we present measurements of contact angles of nine solvents on four different AAO sheets by tensiometric and goniometric methods. From the solvents tested, we found dimethyl sulfoxide (DMSO) and N,N(')-dimethylformamide (DMF) to interact with the AAOs, the polarity of the solvents and the surfaces being the driving force.
RESUMO
The full conformational space of N-acetyl-l-cysteine-N-methylamide was explored by ab initio (RHF/ 6-31G(d)) and DFT (B3LYP/6-31G(d)) computations. Multidimensional conformational analysis predicts 81 structures in N-acetyl-l-cysteine-N-methylamide, but only 47 relaxed structures were previously determined at the RHF/3-21G level of theory. These structures were now optimized using RHF/6-31G(d) and B3LYP/6-31G(d) approaches. Seven conformational migrations were observed when recalculated at higher level of theory. Besides these major changes, only smaller conformational shifts were operative for the remaining stationary points. The exploration of the whole conformational space of N-acetyl-l-cysteine-N-methylamide, including the transition-state structures allowing the conformational interconversion among the low-energy forms, was analyzed in this study. Our results offer new insights into the influence of polar side chains on the conformational preferences of peptide structures.
Assuntos
Acetilcisteína/análogos & derivados , Amidas/química , Biologia Computacional , Acetilcisteína/química , Conformação MolecularRESUMO
Thirty-six two-week-old healthy Holstein-Friesian calves weighing between 52 and 58 kg were divided at random into three groups of 12; group A calves were given a single oral bolus containing 2.5 g sulphathiazole and 1 g trimethoprim in a sustained-release formulation; group B received the same doses of the drugs but the trimethoprim was not in a sustained-release formulation; group C received a bolus containing 2.5 g sulphathiazole and 0.5 g conventional trimethoprim. Blood samples were collected at intervals for two days, the serum was separated and the composite antibacterial activity profiles of the mixture were analysed by an agar-diffusion microbiological method. The mean maximum activities in the serum of the three groups were 23.4 microg/ml in group A, 9.25 microg/ml in group B and 8.01 microg/ml in group C. The mean areas under the curves of the serum activity time curves were 838 microg/ml/hour in group A, 216 microg/ml/hour in group B and 182 microg/ml/hour in group C.