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1.
São Paulo; s.n; s.n; 2022. 80 p. tab, graf.
Thesis in Portuguese | LILACS | ID: biblio-1415544

ABSTRACT

O objetivo deste trabalho foi preparar e caracterizar nanocarreadores via auto-organização a partir da pectina de citros e lisozima para o encapsulamento da ß-lactose. Foram estudadas três condições de interação entre os biopolímeros variando a razão molar pectina/lisozima (3:1, 2:1, 1:1, 1:2 e 1:3), o pH e o tempo de aquecimento. A confirmação da interação foi determinada por espectroscopia no infravermelho por transformada de Fourier (FTIR) e por calorimetria de varredura diferencial (DSC). Os espectros de infravermelho evidenciaram que ligações de hidrogênio foram as principais forças envolvidas na formação dos nanocarreadores e sugeriram a ausência de ß-lactose livre na superfície das nanopartículas. Os termogramas evidenciaram que as nanopartículas formadas na presença de ß-lactose têm maior estabilidade térmica do que as nanopartículas sem ß-lactose. Para ambas as formulações estudadas, na presença e na ausência de ß-lactose, a formação das nanopartículas ocorreu entre os valores de pKa e ponto isoelétrico (pI) da pectina e lisozima, respectivamente, sendo a melhor razão de interação pectina/lisozima 1:2, em pH 10, a 80 ºC por 30 min. As nanopartículas foram formadas via auto-organização e todos as partículas apresentaram distribuição de tamanho homogênea, formato esférico, diâmetro inferior a 100 nm e carga superficial negativa. A morfologia e o tamanho das partículas pouco alteraram com a incorporação da -lactose. A eficiência de encapsulação (EE) da ß-lactose foi superior a 96% para as concentrações estudadas. Ensaios preliminares in vitro, em células epiteliais de câncer de cólon (HCT-116), evidenciaram que as nanopartículas formadas são capazes de adentrar no meio intracelular, possivelmente, por via endocitose


This work aimed to prepare and characterize nanocarriers via self-assembly using citrus pectin and lysozyme for ß-lactose encapsulation. Three interaction conditions between the biopolymers were studied, varying the pectin/lysozyme molar ratio (3:1, 2:1, 1:1, 1:2 and 1:3), pH and heating time. Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) determined the interaction's confirmation. The infrared spectra showed that hydrogen bonds were the main forces involved in the formation of nanocarriers and suggested the absence of free ß-lactose on the surface of the nanoparticles. The thermograms showed that nanoparticles formed in the presence of ß-lactose have greater thermal stability than nanoparticles without ß-lactose. For both formulations studied, in the presence and absence of lactose, the formation of nanoparticles occurred between the pKa and isoelectric point (pI) values of pectin and lysozyme, respectively, with the best pectin/lysozyme interaction molar ratio 1:2, at pH 10, at 80 °C for 30 min. Nanoparticles were formed via self-assembly, and all particles presented homogeneous size distribution, spherical shape, diameter less than 100 nm, and negative surface charge. The morphology and size of the particles changed little with the incorporation of ß-lactose. The encapsulation efficiency (EE) of ß-lactose was higher than 96% for the concentrations studied. Preliminary in vitro assays in colon cancer epithelial cells (HCT-116) showed that the nanoparticles formed are capable of entering the intracellular medium, possibly via endocytosis


Subject(s)
Muramidase/analysis , Pectins/analysis , Biopolymers/adverse effects , Calorimetry , Calorimetry, Differential Scanning/methods , Spectroscopy, Fourier Transform Infrared/methods , Colonic Neoplasms , Nanoparticles , Hydrogen-Ion Concentration , Lactose
2.
São Paulo; s.n; s.n; 2021. 123 p. tab, graf, ilus.
Thesis in Portuguese | LILACS | ID: biblio-1380006

ABSTRACT

Diante das exigências crescentes das agências regulatórias do mundo todo quanto à redução/eliminação de ácidos graxos trans nos alimentos industrializados, bem como da conscientização do consumidor sobre a relação entre alimentação e saúde, o desenvolvimento de alternativas mais saudáveis aos óleos parcialmente hidrogenados e a outras fontes lipídicas com alto grau de saturaçã o se faz necessário. O oleogel, um sistema composto por um óleo preso em uma rede tridimensional formada por um agente estruturante, se apresenta como uma solução promissora. Dentre os diversos agentes estruturantes, as ceras vegetais se destacam por sua excelente capacidade de gelificação de óleos. Contudo, apresentam uma desvantagem sob o aspecto sensorial, pois podem conferir cerosidade e sabor residual desagradável aos alimentos. Com o objetivo de viabilizar o uso das ceras como agentes estruturantes em oleogéis face ao seu excelente desempenho tecnológico, este projeto propõe o estudo e a aplicação de oleogéis à base de óleo de soja (SBO) estruturado com ceras de farelo de arroz (RBW) a 2 e 4 % (m/m) ou carnaúba (CBW) a 3 e 6% (m/m), isoladamente. As matérias-primas foram caracterizadas e o comportamento de gelificação de cada cera foi avaliado por análises de textura por penetração de cone, estabilidade à perda de óleo por centrifugação, energia coesiva por parâmetro de solubilidade de Hansen (HSP) e comportamento de cristalização e fusão por calorimetria exploratória diferencial (DSC). Os resultados mostraram que ambas as ceras são capazes de formar oleogéis estruturalmente estáveis, contudo, o oleogel com 2% de RBW apresentou maior firmeza a 20 °C (190,4 gf/cm2) do que o oleogel com 6% de CBW a 5 °C (186,1 gf/cm2). Ao final de 5 dias, a capacidade de retenção de óleo do oleogel preparado com RBW foi de 100% às concentrações de 2 e 4% (m/m), contra 61 e 99,3% do oleogel elaborado com CBW às concentrações de 3 e 6% (m/m), respectivamente. Esses resultados podem ser explicados pela diferença entre as energias coesivas, ou seja, do grau de interação molecular entre o solvente e o soluto de cada oleogel. De acordo com os resultados de distância, que prevê se o gel formado será forte, fraco ou se não haverá formação de gel, o soluto CBW apresentou menor interação com o óleo (3,3 MPa1/2) do que o soluto RBW (3,7 MPa1/2). Os oleogéis foram aplicados como ingredientes em diferentes formulações de cream cheese, que foram analisados quanto a diferentes parâmetros de textura e esses resultados foram comparados a uma referência comercial. Nenhuma das amostras produzidas obteve resultados de textura estatisticamente iguais aos do cream cheese comercial (CC), o que pode ser explicado pelas diferenças de formulação e processamento dos produtos. Face aos resultados para textura e estabilidade à perda de óleo dos oleogéis de RBW, este agente estruturante apresenta ria maior potencial de aplicação, porém o oleogel CBW6 obteve alta capacidade de retenção de óleo (99,3%) e quando aplicado na formulação de cream cheese (CCBW6) apresentou resultados de firmeza e espalhabilidade mais próximos da amostra de referência, feita com gordura do leite (CMF)


Given the growing demands of regulatory agencies around the world regarding the reduction/elimination of trans fatty acids in processed foods, as well as consumer awareness about the relationship between food and health, the development of healthier alternatives to partially hydrogenated oils and others lipid sources with a high degree of saturation are necessary. Oleogel, a system composed of an oil trapped in a three-dimensional network formed by a structuring agent, presents itself as a promising solution. Among the various structuring agents, vegetable waxes stand out for their excellent oil gelling capacity. However, they have a sensory disadvantage, as they can give waxy and unpleasant aftertaste to foods. Aiming at enabling the use of waxes as structuring agents in oleogels in view of their excellent technological performance, this study proposes the evaluation and application of oleogels based on soybean oil (SBO) structured with rice bran wax (RBW) at 2 and 4% (m/m) or carnauba (CBW) at 3 and 6% (m/m). The raw materials were characterized and the gelling behavior of each wax was evaluated by analysis of texture by cone penetration, stability to oil loss by centrifugation, cohesive energy by Hansen solubility parameter (HSP) and crystallization and melting behavior. by differential scanning calorimetry (DSC). The results showed that both waxes are able to form structurally stable oleogels, however, oleogel with 2% RBW showed greater firmness at 20 °C (190.4 gf/cm2) than oleogel with 6% CBW at 5° C (186.1 gf/cm2). At the end of 5 days, the oil retention capacity of oleogel prepared with RBW was 100% at concentrations of 2 and 4% (m/m), against 61 and 99.3% of oleogel prepared with CBW at concentrations of 3 and 6% (m/m), respectively. These results can be explained by the difference between the cohesive energies, that is, the degree of molecular interaction between the solvent and the solute of each oleogel. According to the distance results, which predicts if the formed gel will be strong, weak or if there will be no gel formation, the CBW solute showed less interaction with the oil (3.3 MPa1/2) than the RBW solute (3 ,7 MPa1/2). Oleogels were applied as ingredients in different cream cheese formulations, which were analyzed for different texture parameters and these results were compared to a commercial reference. None of the samples produced had texture results statistically equal to those of commercial cream cheese (CC), which can be explained by the differences in formulation and processing of the products. Given the results for texture and oil binding capacity of RBW oleogels, this structuring agent would present greater application potential, but CBW6 oleogel obtained high oil biding capacity (99.3%) and when applied in cream cheese formulation (CCBW6) showed firmness and spreadability results closer to the reference sample, made with milk fat (CMF)


Subject(s)
Chemistry, Pharmaceutical , Industrialized Foods , Food/adverse effects , Vegetables , Waxes/pharmacology , Soybean Oil/classification , Calorimetry/methods , Calorimetry, Differential Scanning/methods
3.
São Paulo; s.n; s.n; 2021. 199 p. tab, graf, ilus.
Thesis in Portuguese | LILACS | ID: biblio-1380756

ABSTRACT

O achocolatado em pó é um dos derivados do cacau com maior inserção econômica e cultural em diversos países. O objetivo deste estudo foi avaliar a adição de ingredientes diferenciados nesse tipo de produto, como modificadores reológicos e fruta, bem como à alteração no tipo de cacau utilizado, ocasionando mudanças sensoriais e nutricionais positivas ao produto. O fruto sugerido neste estudo foi o cupuaçu (Theoboroma grandiflorum), fruto típico da região Norte, que apresenta excelente qualidade nutricional. Foram desenvolvidas 7 formulações de achocolatado por método convencional após simples mistura (padrão, com cacau alcalino, com cacau orgânico, com polpa de cupuaçu, com amido pré-gelatinizado, com amido pré-gelatinizado + polpa de cupuaçu, com goma guar, com goma guar + polpa de cupuaçu) e 4 formulações processadas por spray dryer após a simples mistura (padrão, com polpa de cupuaçu, com amido pré-gelatinizado, com amido + polpa de cupuaçu). Todas as formulações foram avaliadas quanto à composição nutricional, calorimetria exploratória de varredura (DSC), análises físico-químicas, reológica, quantificação dos compostos fenólicos e avaliação da capacidade antioxidante por métodos in vitro. Em seguida foi realizada análise sensorial com as formulações: padrão, com polpa de cupuaçu e com amido + polpa de cupuaçu. O achocolatado padrão apresentou tempo de mistura de 38 min, o que foi utilizado como parâmetro para as demais formulações. Os achocolatados que continham polpa de cupuaçu apresentaram maior teor proteico (14,5 a 16,3 g/100g) quando comparados com o padrão (13,6 g/100g). Todos os achocolatados apresentaram umidade entre 1,2% e 3,7%, e atividade de água entre 0,13 e 0,57, considerados microbiologicamente estáveis, sendo bom para a vida útil do produto. Os achocolatados obtiveram tempo de molhabilidade entre 07:15 min e 15:06 min; solubilidade de 1,56 IR% a 7,44 IR%; tamanho de partícula variando entre 0,216 mm e 0,347 mm (partículas finas). O uso do spray dryer não teve impacto significativo nas características físicas das formulações, assim como a utilização dos diferentes tipos de cacau não afetou a composição nutricional e qualidade física dos achocolatados. Houve aumento (p< 0,05) para o tempo de molhabilidade e solubilidade do achocolatado com cacau orgânico em comparação com o padrão (13:30 e 9:33 min; 2,64 e 1,56 IR%, respectivamente). A transição vítrea variou entre 35,2 a 35,7 mW enquanto o ponto de carbonização ficou entre 237,4 a 243,6 mW, indicando que a adição dos agentes espessantes e/ou do cupuaçu não interferiu (p<0,05) na análise térmica dos achocolatados. Todos os achocolatados diluídos em leite apresentaram-se como pseudoplásticos, com aumento de viscosidade nas menores temperaturas, conforme esperado. O achocolatado com cacau orgânico apresentou o maior teor de compostos fenólicos (8,27 mg AG g-1) enquanto observou-se redução no conteúdo de fenólicos nos produtos processados por spray dryer. Os achocolatados apresentaram capacidade antioxidante entre 31,76 µMETrolox/g e 75,62 µMETrolox/g, pelo método do DPPH. A adição do cupuaçu levou ao aumento da capacidade de sequestro de radicais DPPH quando comprados com o padrão (p<0,05). Não foi observada diferença significativa pelo método FRAP. A avaliação sensorial obteve aceitação situada na região positiva da escala (5 a 7). Os achocolatados formulados apresentam formulações adequadas a sua comercialização, com agregação de valor nutricional e econômico


The chocolate powdered is a cocoa-derived with greater economic and cultural integration in several countries. The objective of this study was to evaluate the addition of different ingredients in this type of product, such as rheological modifiers and fruit, as well as the change in the type of cocoa used, causing positive sensory and nutritional changes to the product. The fruit suggested in this study was cupuassu (Theoboroma grandiflorum), a typical fruit from the northern region, which has excellent nutritional quality. Seven powdered chocolate formulations were developed by conventional method after simple mixing (standard, with alkaline cocoa, with organic cocoa, with cupuassu pulp, pre-gelatinized starch, pre-gelatinized starch + cupuassu pulp, guar gum, with guar gum + cupuassu pulp) and 4 formulations processed by spray dryer after simple mixing (standard, with cupuassu pulp, pre-gelatinized starch, starch + cupuassu pulp). All formulations were evaluated for nutritional composition, differential scanning calorimetry (DSC), physicochemical, rheological analyzes, quantification of phenolic compounds and antioxidant capacity evaluation by in vitro methods. Then, sensory analysis was performed with the formulations: standard, with cupuassu pulp and starch + cupuassu pulp. The standard powdered chocolate had a mixing time of 38 min, which was used as parameter for the other formulations. The powdered chocolate containing cupuassu pulp had higher protein content (14.5 to 16.3 g / 100g) when compared to the standard (13.6 g / 100g). All powdered chocolate presented humidity between 1.2% and 3.7%, and water activity between 0.13 and 0.57, considered microbiologically stable, wich is good for the shelf life of the product. The powdered chocolate obtained wettability time between 07:15 min and 15:06 min; solubility from 1.56 IR% to 7.44 IR%; particle size ranging from 0.216 mm to 0.347 mm (fine particles). The use of the spray dryer had no significant impact on the physical characteristics of the formulations, as well as the use of different types of cocoa did not affect the nutritional composition and physical quality of the powdered chocolate. There was an increase (p <0.05) for the time of wettability and solubility in chocolate powdered formulated with organic cocoa when compared to the standard (9:33 and 13:30 min; IR 2.64 and 1.56%, respectively). The glass transition ranged from 35.2 to 35.7 mW while the carbonization point ranged from 237.4 to 243.6 mW, indicating that the addition of thickening agents and / or cupuassu did not interfere (p <0.05) in the thermal analysis of powdered chocolate. All powdered chocolate when diluted in milk presented as pseudoplastics, with viscosity increase at lower temperatures, as expected. Chocolate powdered with organic cocoa presented the highest content of phenolic compounds (8.27 mg AG g-1) whereas there was a reduction in phenolic content in products processed by spray dryer. The powdered chocolates presented antioxidant capacity between 31.76 µMETrolox / g and 75.62 µMETrolox / g, by the DPPH method. The addition of cupuassu led to increased ability to sequester DPPH radicals when compared to the standard (p <0.05). No significant difference was observed by the FRAP method. Sensory evaluation was accepted in the positive region of the scale (5 to 7). The formulated powdered chocolates have appropriate formulations for marketing, with added nutritional and economic value


Subject(s)
Chocolate/analysis , Food Ingredients/analysis , Fruit/classification , Powders , In Vitro Techniques/methods , Cacao/anatomy & histology , Calorimetry/methods , Phenolic Compounds , Antioxidants/adverse effects , Nutritive Value
4.
Belo Horizonte; s.n; 2020. 83 p. ilus, tab.
Thesis in Portuguese | BBO, LILACS | ID: biblio-1253965

ABSTRACT

As características geométricas e técnicas de fabricação das limas endodônticas afetam o desempenho clínico e sua resistência à fratura, flexibilidade e outras propriedades. Um parâmetro muito explorado na Endodontia é a utilização de tratamentos térmicos, que promovem um aumento na resistência à fadiga e flexibilidade destes materiais. Neste estudo pretendeu-se avaliar o efeito de diferentes processos de tratamento térmico/usinagem nas propriedades físicas, flexibilidade, resistência torcional e à fadiga flexural dos instrumentos Prodesign Logic (PDL), verificando se a sequência de processamento dos instrumentos levaria a comportamentos mecânicos diferentes. Este sistema é fabricado a partir de um método inovador que envolve a realização do tratamento térmico para obtenção de memória de forma no fio NiTi anteriormente à usinagem. A hipótese nula a ser testada é que o momento de aplicação dos procedimentos de tratamento térmico e usinagem não afetariam as propriedades físicas e mecânicas de instrumentos endodônticos de NiTi. Para grupos de comparação, foram utilizados protótipos de instrumentos com as mesmas características geométricas e dimensionais, sendo um grupo de instrumentos sem tratamento térmico aplicado (SEP) e outro com o tratamento térmico realizado de forma convencional, após a usinagem do instrumento (HTP). Foram realizadas caracterização física e microestrutural com ensaios de calorimetria exploratória diferencial (DSC) e testes de difratometria de Raios-X (DRX), além de ensaios mecânicos divididos em testes de torção, dobramento em 45 e resistência à fadiga flexural. Os resultados mostraram que macroscopicamente não houve nenhuma alteração importante nas características dos três grupos de instrumentos, exceto mudanças de cor devido a diferentes sequências de processamento. Os resultados de DSC mostraram que à temperatura ambiente a liga é principalmente austenítica no grupo SEP e que após o tratamento térmico realizado nos grupos PDL e HTP, houve uma mudança nas temperaturas de transformação, com um aumento da temperatura de Af e predominância da liga NiTi em fase R. Os resultados de XDR confirmaram os achados do DSC. As diferenças nos parâmetros medidos entre diferentes tipos de instrumentos nos ensaios de resistência torcional, dobramento a 45º e fadiga flexural foi sempre considerada com um nível de significância de 95%. Os resultados para os ensaios de flexão mostraram que o grupo HTP mostrou-se o mais flexível, com os mais baixos valores de momento de dobramento, seguido por PDL e SEP. Nos resultados dos ensaios de torção foi possível observar que SEP apresentou valores mais altos de torque seguido por PDL e HTP (p<.05). Os ensaios de resistência à fadiga mostraram valores médios de NCF maiores para HTP, seguido por PDL e SEP. Entretanto, um pior comportamento do PDL só seria evidenciado clinicamente se os instrumentos fossem usados um número de vezes maior do que o recomendado pelo fabricante. Pode-se concluir que alterar o processo de fabricação dos instrumentos endodônticos, invertendo-se as etapas de usinagem e tratamento térmico, levou, de fato, a uma mudança no comportamento mecânico de instrumentos Prodesign Logic em relação aos prótótipos.


The geometric characteristics and manufacturing techniques of endodontic instruments affect clinical performance, fracture resistance, flexibility and other properties. A parameter widely explored in Endodontics is the use of heat treatments, which promote an increase in the resistance to fatigue and flexibility of these materials. This study aimed to evaluate the effect of different heat treatment / machining processes on the physical properties, flexibility, torsional strength and flexural fatigue of Prodesign Logic (PDL) instruments, verifying whether the processing sequence of the instruments would lead to different mechanical behaviors. This system is manufactured using an innovative method that involves performing thermal treatment to obtain shape memory in the NiTi wire prior to machining. The null hypothesis to be tested is that the moment of application of the heat treatment and machining procedures would not affect the physical and mechanical properties of NiTi endodontic instruments. For comparison groups, instrument prototypes with the same geometric and dimensional characteristics were used, being one group of instruments without thermal treatment applied (SEP) and another with thermal treatment carried out in a conventional manner, after machining the instrument (HTP). Physical and microstructural characterization were performed with differential scanning calorimetry (DSC) tests and X-ray diffractometry (XRD) tests, in addition to mechanical tests divided into torsion tests, 45° bending and resistance to flexural fatigue. The results showed that macroscopically there were no major change in the characteristics of the three groups of instruments, except for color changes due to different processing sequences. The DSC results showed that at room temperature the alloy is mainly austenitic in the SEP group and that after the heat treatment carried out in the PDL and HTP groups, there was a change in the transformation temperatures, with an increase in the Af temperature and predominance of the NiTi alloy in phase R. The XRD results confirmed the DSC findings. Differences in the parameters measured between different types of instruments in the tests of torsional resistance, bending at 45º and flexural fatigue were always considered with a significance level of 95%. The results for the flexibility tests showed that the HTP group proved to be the most flexible, with the lowest values, followed by PDL and SEP. In the results of the torsion tests it was possible to observe that SEP presented higher values of torque followed by PDL and HTP (p <.05). Fatigue resistance tests showed higher mean NCF values for HTP, followed by PDL and SEP. However, a worse behavior of the PDL would only be evidenced clinically if the instruments were used several times greater than that recommended by the manufacturer. It can be concluded that changing the manufacturing process of endodontic instruments, inverting the machining and heat treatment steps, led, in fact, to a change in the mechanical behavior of Prodesign Logic instruments in relation to the prototypes.


Subject(s)
Calorimetry , Dental Instruments , Endodontics/instrumentation , Tensile Strength , Pliability
5.
Biomedical and Environmental Sciences ; (12): 566-572, 2020.
Article in English | WPRIM | ID: wpr-828978

ABSTRACT

Objective@#This study aimed to measure the basal energy expenditure (BEE) of Chinese healthy adults and establish an accurate predictive equation for this population.@*Methods@#In total, 470 Chinese healthy adults had their BEE measured using the Cosmed K4b portable metabolic system. Multiple linear regression analysis was applied to develop new optimal equations for predicting BEE. The bias, accuracy rate, concordance correlation coefficient (CCC), and root mean square error (RMSE) were used to evaluate the accuracy of the predictive equations.@*Results@#There was a significant difference in BEE between males and females, with 5,954 kJ/d and 5,089 kJ/d, respectively. People living in rural areas expended significantly higher BEE (5,885 kJ/d) than those in urban areas (5,279 kJ/d). Previous equations developed by Henry, Schofield, Harris-Benedict (H-B), and Liu overestimated the BEE of Chinese healthy adults. The new equations derived from the present study displayed the smallest average bias and RMSE from the measured basal energy expenditure (mBEE). The CCC of the new equations was higher than other predictive equations, but it was lower than 0.8. There was no significant difference in the accuracy rate among all predictive equations.@*Conclusions@#Sex and regional differences in BEE were observed in Chinese healthy adults. Neither the widely used previous predictive equations nor the one derived in the present study were accurate enough for estimating the BEE of Chinese healthy adults. Further study is required to develop more accurate equations for predicting the BEE of Chinese healthy adults aged between 20-45 years.


Subject(s)
Adult , Female , Humans , Male , Young Adult , Basal Metabolism , Calorimetry , Methods , China
6.
Int. j. high dilution res ; 19(3): 18-26, 2020.
Article in English | LILACS, HomeoIndex | ID: biblio-1146524

ABSTRACT

Background:High and ultra-low doses of HgCl2modulate α-amylase starch interaction through two different binding sites of the enzyme. Mercurius corrosivus at ultra-high dilution (UHD) is reported to have a long duration of action for 30-60 days.Objectives:(i) To see whether the mother tincture and UHDs of mercuric chloride could directly act on α-amylase without intervention of its substrate starch. (ii) To see whether the MT and UHDs produce longer binding interaction with α-amylase than the control.Methods:Mercuric chloride MT (0.15 M) or Merc corθ and its three UHDs, 30, 200, 1000 cH called potencies were in 90% ethanol. Blank 90% ethanol and deionised and distilled (DD) water were used as controls. All ethanol based ligands were diluted with DD water to reduce EtOH content to 0.09%. Using an ITC instrument each ligand was injected once at 10 µl into15µM α-amylase at 250C and the reaction was observed for 33.3 min. Results:While Merccorθ produced endothermic reaction, all other ligands did exothermic reaction. All ligands sustained heat change for the entire period of observation (33.3 min). Conclusions:Merc corθ and potencies produced exactly the opposite reaction at the protein binding sites. Merc cor200 cH and 1000 cH produced highest heat change (6 micro cal/sec) during interaction with α-amylase.(AU)


Subject(s)
Calorimetry , High Potencies , Homeopathy , Mercuric Chloride
7.
Braz. arch. biol. technol ; 63: e20190339, 2020. graf
Article in English | LILACS | ID: biblio-1132187

ABSTRACT

Abstract Conventional orthodontic treatment with the use of stainless steel may be detrimental to oral health by promoting demineralizing lesions appearance and increasing adhesion and formation of bacterial biofilm, inducing the development of cavities. An alternative that has been researched to reduce the side effects of orthodontic treatment is the coating of materials with antimicrobial nanoparticles. Nanometric- sized particles increase their surface area and contact with the microbial membrane, consequently intensifying their bacteriostatic and bactericidal effect. In this work, hydrothermal synthesis, a "green" process was used to attach silver nanoparticles (AgNPs) to the surface of two different brands of orthodontic wires. The coated materials were analyzed for their physicochemical properties by scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC), which showed the distribution of AgNPs along the wires without modifying their properties. In the microbiological test, one of the brands showed a statistically significant difference in microbial adhesion and biofilm formation by Staphylococcus aureus and Streptococcus mutans. Results lead to the conclusion that antimicrobial orthodontic wires coated with silver nanoparticles through hydrothermal synthesis is a promising material for the improvement of orthodontic treatment.


Subject(s)
Orthodontic Wires , Staphylococcus aureus/drug effects , Streptococcus mutans/drug effects , Metal Nanoparticles , Anti-Bacterial Agents/pharmacology , Silver , Bacterial Adhesion , Calorimetry , Microscopy, Electron, Scanning , Dental Plaque
8.
Bol. latinoam. Caribe plantas med. aromát ; 17(6): 566-574, nov. 2018. tab, ilus
Article in English | LILACS | ID: biblio-1007336

ABSTRACT

The composition of the essential oil obtained by hydrodistillation from Minthostachys mollis Griseb (Lamiaceae) aerial parts was determined by GC and GC/MS. Menthone (13.2%), pulegone (12.4%), cis-dihydrocarvone (9.8%) and carvacrol acetate (8.8%) were the main essential oil components. The cytotoxic activity of the essential oil was in vitro measured using the MTT colorimetric assay. IC50 values were calculated on healthy non-tumor cells (HEK-293) and three human cancer cell lines (T24, DU-145 and MCF-7). In such latter cells, the estimated values were around 0.2 mg/mL. In addition, the antioxidant activity was determined by interaction with the stable free radical 2,2"-diphenyl-1-picrylhydrazyl. The essential oil was almost devoid of antioxidant activity indicating that its anti-proliferative action relies on other unknown mechanism.


La composición del aceite esencial obtenido por hidrodestilación a partir de partes aéreas de Minthostachys mollis Griseb (Lamiaceae) se determinó mediante GC y GC/MS. Mentona (13.2%), pulegona (12.4%), junto con cis-dihidrocarvona (9.8%) y acetato de carvacrol (8.8%) fueron los principales componentes del aceite esencial. La actividad citotóxica del aceite esencial se midió in vitro utilizando el ensayo colorimétrico MTT tanto en células sanas no tumorales (HEK-293) como en tres líneas celulares de cáncer humano (T24, DU-145 y MCF-7). Los valores de IC50 calculados fueron de alrededor de 0.2 mg/mL. Además, se determinó la actividad antioxidante por su interacción con el radical libre 2,2"-difenil-1-picrilhidrazilo. El aceite esencial tiene baja actividad antioxidante, lo que indica que su acción antiproliferativa depende de otro mecanismo desconocido.


Subject(s)
Oils, Volatile/pharmacology , Lamiaceae , Cell Line, Tumor/drug effects , Antioxidants/pharmacology , Peru , Picrates , Terpenes/analysis , Biological Assay , Biphenyl Compounds , Calorimetry , Oils, Volatile/chemistry , Cell Survival/drug effects , Free Radical Scavengers , Gas Chromatography-Mass Spectrometry , Antioxidants/chemistry
9.
Pesqui. bras. odontopediatria clín. integr ; 17(1): e2833, 13/01/2017. tab, graf
Article in English | LILACS, BBO | ID: biblio-914291

ABSTRACT

Objective: To evaluate the influence of four different photoinitiators on the polymerization kinetics and marginal microleakage in class V restorations using photopolymerizable dental composites. Material and Methods: Four photopolymerizable dental composites based on Bis-GMA (14.5 wt %), UDMA (6.5 wt %) and silanized filler particles (79 wt %) containing different photoinitiators were formulated. Camphorquinone (CQ)/amine, phenyl-propanedione (PPD), monoacylphosphine oxide (Lucirin® TPO) and bisacylphosphine oxide (Irgacure® 819) were used as photoinitiators. Sixteen intact human third molars were selected and divided into four groups. All teeth received class V cavity preparations in their buccal and lingual surfaces and were submitted to a dye leakage test. Data were independently analyzed for both enamel and dentin, and the results were assessed by a Kruskal-Walis test. The polymerization reactions of the four composites were evaluated by differential scanning calorimeter coupled with photocalorimeter accessory. Results: Lucirin® TPO presented the highest scores for microleakage in enamel, whereas the other photoinitiators have not demonstrated statistical differences. The lowest scores were obtained for PPD in dentin while the highest scores have been achieved by Irgacure® 819 and Lucirin® TPO. Photocalorimetric measurements demonstrated a correlation between polymerization reaction rate and marginal leakage, showing that faster reactions cause greater marginal leakage. Conclusion: Marginal microleakage scores in photopolymerizable dental composites can be greatly influenced by different types of photoinitiators through their distinct reaction rates.


Subject(s)
Humans , Composite Resins/chemistry , Dental Materials , Photoinitiators, Dental/chemistry , Polymerization , Molar , Brazil , Calorimetry/methods , Statistics, Nonparametric
10.
Acta odontol. latinoam ; 30(1): 33-38, 2017. ilus, tab, graf
Article in English | LILACS | ID: biblio-907405

ABSTRACT

The aim of this study was to analyze in vitro temperature changeson the outer surface of the dental root during mechanical fillingremoval procedures.Thirty recently extracted single­rooted lower premolars were cuttransversally at 16 mm from the apex in order to standardizesample length. Endodontic treatment was performed on them. Thefilling material was subsequently removed using Gates Glidden(G1, G2, G3); Peeso (P1, P2, P3) and PostecPlus FRC (FRC)reamers while temperatures were measured on the outer surfaceusing a digital device with thermocouple at 0, 2, 4, 6, 8, 10 and 15seconds. Temperatures were compared using repeated measuresANOVA followed by pairwise comparison with Tukey’s test.All reamers caused significant temperature variation betweendifferent times (p<0.05). Pairwise comparisons indicated thattemperature increased with time for all reamers (p<0.05).Significant differences in temperature were found betweendifferent reamers after 0, 2, 4, 6, 8, 10 and 15 seconds (p<0.05)...


El objetivo del presente trabajo fue estudiar los cambios térmicosin vitro en la superficie externa de la raíz del diente, generadosdurante los procedimientos de desobturación mecánica.Se utilizaron 30 premolares inferiores unirradiculares reciente ­mente extraídos, que fueron seccionados transversalmente a16 mm del ápice para estandardizar la longitud de lasmuestras. Se realizó luego su tratamiento endodóntico. Lasmediciones de temperatura fueron realizadas mediante undispositivo digital con termocupla, en la superficie externa adiferentes tiempos (t = 0, 2, 4, 6, 8, 10 y 15 segundos), durantela desobturación con fresas de Gates Glidden (G1, G2, G3);de Peeso (P1, P2, P3) y la correspondiente a PostecPlus FRC(FRC). Los registros de temperatura fueron comparadosmediante pruebas de ANOVA de medidas repetidas, seguidaspor comparaciones entre pares mediante la prueba de Tukey.Con todas las fresas se encontró una variación significativa dela temperatura entre los diferentes tiempos (p<0.05). Las compa ­raciones entre pares indicaron que la temperatura se incrementócon el tiempo en todas las fresas (p<0.05). Se detectarondiferencias significativas de temperatura entre diferentes fresasdespués de 0, 2, 4, 6, 8, 10 y 15 segundos (p<0.05)...


Subject(s)
Humans , Dental Instruments , Root Canal Preparation/instrumentation , Transition Temperature , Tooth Root/physiology , Analysis of Variance , Calorimetry/methods , In Vitro Techniques , Data Interpretation, Statistical
11.
Rev. Assoc. Med. Bras. (1992, Impr.) ; 62(7): 672-679, Oct. 2016. tab
Article in English | LILACS | ID: biblio-829513

ABSTRACT

Summary Patients on intensive care present systemic, metabolic, and hormonal alterations that may adversely affect their nutritional condition and lead to fast and important depletion of lean mass and malnutrition. Several factors and medical conditions can influence the energy expenditure (EE) of critically ill patients, such as age, gender, surgery, serious infections, medications, ventilation modality, and organ dysfunction. Clinical conditions that can present with EE change include acute kidney injury, a complex disorder commonly seen in critically ill patients with manifestations that can range from minimum elevations in serum creatinine to renal failure requiring dialysis. The nutritional needs of this population are therefore complex, and determining the resting energy expenditure is essential to adjust the nutritional supply and to plan a proper diet, ensuring that energy requirements are met and avoiding complications associated with overfeeding and underfeeding. Several evaluation methods of EE in this population have been described, but all of them have limitations. Such methods include direct calorimetry, doubly labeled water, indirect calorimetry (IC), various predictive equations, and, more recently, the rule of thumb (kcal/kg of body weight). Currently, IC is considered the gold standard.


Resumo Os pacientes em cuidados intensivos apresentam alterações sistêmicas, metabólicas e hormonais, que podem afetar adversamente a condição nutricional e levar à rápida e importante depleção da massa magra e desnutrição. Vários fatores e situações clínicas podem exercer influência sobre o gasto energético (GE) de pacientes críticos, como idade, sexo, cirurgias, infecções graves, medicamentos, modalidade ventilatória e disfunção de órgãos. Dentre as condições clínicas que podem cursar com alteração do GE, encontra-se a lesão renal aguda (LRA), distúrbio complexo comumente observado em pacientes críticos, com manifestações que podem variar de mínimas elevações na creatinina sérica até insuficiência renal com necessidade dialítica. Dessa forma, essa população crítica apresenta necessidades nutricionais complexas e a determinação do gasto energético de repouso (GER) torna-se essencial para o ajuste da oferta nutricional e para o planejamento de uma nutrição adequada, assegurando que as necessidades energéticas sejam atingidas e evitando as complicações associadas à hiper ou hipoalimentação. Diversos métodos de avaliação do GE nessa população foram descritos, mas todos apresentam limitações. Dentre eles, destacam-se a calorimetria direta, a água duplamente marcada, a calorimetria indireta (CI), diversas equações preditivas e, mais atualmente, a regra de bolso (kcal/kg de peso). Atualmente, a CI é eleita o método padrão-ouro.


Subject(s)
Humans , Male , Female , Rest/physiology , Calorimetry/methods , Critical Illness , Energy Metabolism/physiology , Algorithms , Predictive Value of Tests , Acute Kidney Injury/metabolism , Nutritional Requirements
12.
Braz. j. pharm. sci ; 52(3): 443-446, July-Sept. 2016. tab, graf
Article in English | LILACS | ID: biblio-828257

ABSTRACT

ABSTRACT The interaction between 6-shogaol, a pharmacologically active ginger constituent, and human serum albumin (HSA), the main in vivo drug transporter, was investigated using isothermal titration calorimetry (ITC). The value of the binding constant, Ka (5.02 ± 1.37 × 104 M−1) obtained for the 6-shogaol-HSA system suggested intermediate affinity. Analysis of the ITC data revealed feasibility of the binding reaction due to favorable enthalpy and entropy changes. The values of the thermodynamic parameters suggested involvement of van der Waals forces, hydrogen bonds and hydrophobic interactions in the 6-shogaol-HSA complex formation.


Subject(s)
Thermodynamics , Zingiber officinale/anatomy & histology , Biological Products/pharmacokinetics , Calorimetry , Serum Albumin/analysis
13.
Biosci. j. (Online) ; 31(3): 841-849, may./jun. 2015.
Article in Portuguese | LILACS | ID: biblio-963892

ABSTRACT

Objetivou-se com este trabalho mensurar a respirometria e a emissão de metano entérico por ovinos alimentados com o capim-elefante cortado aos 56, 84 e 112 dias de crescimento. Foram utilizados 18 carneiros adultos sem raça definida, com peso médio de 34,7 ± 6 kg alojados em gaiolas de estudo de metabolismo. A mensuração dos gases foi realizada através de uma câmara respirométrica de fluxo aberto. O delineamento experimental utilizado foi inteiramente casualizado, com seis repetições, e as médias foram comparadas pelo teste SNK (P<0,05). Os animais alimentados com o capim colhido após 56 dias de rebrotação consumiram mais oxigênio e produziram mais dióxido de carbono e metano. As produções de calor variaram 87,19 a 143,57 Kcal/kg 0,75/dia. O coeficiente respiratório foi semelhante entre os tratamentos, com valor médio de 0,98. A produção de metano variou entre 11,74 e 22,51 g/dia, havendo redução com o aumento da idade da planta forrageira. Quando expressa em g/kg0,75/dia, a produção deste gás foi superior para animais que receberam o capim-elefante-verde cortado aos 56 dias de idade (1,53 g/kg 0,75/dia). A emissão de metano (g) por quilo de matéria seca (MS) e de fibra insolúvel em detergente neutro (FDN) consumido para o capim colhido mais novo (56 dias) foi superior à do capim colhido no estádio mais avanço de maturação (112 dias). Porém, as emissões de metano em gramas por quilo de MS digestível (27,2 g/kg) e FDN digestível (44,4 g/kg) foram semelhantes para os capins colhidos nas diferentes idades de corte. A emissão diária de metano (g/kg 0,75/dia) foi maior em animais alimentados com a planta forrageira colhida mais nova, enquanto que se expressa em gramas por quilo de MS ou FDN digestível a emissão deste gás não sofreu influência do capim-elefante no momento do corte.


The aim of this work was to determinate the respirometry and enteric methane emission from sheep fed fresh elephant grass cut at 56, 84 and 112 days of regrowth. Eighteen crossbred sheep (34.7 ± 6 kg) individually housed in metabolic crates were used in this experiment. The gases measurements were accomplished with an open circuit respirometric chamber. The experimental design was completely randomized with three treatments (grass regowth age) and six repetitions (sheep). The data were subjected to ANOVA and means were compared by SNK test (P<0.05). The animals fed with elephant grass harvested at 56 days of regrowth had higher oxygen uptake and carbon dioxide and methane emissions. Heat production ranged from 87.19 to 143.57 Kcal/kg 0.75/day. The respiratory quotients were similar (P>0.05) among treatments, averaging 0.98. Methane emissions ranged from 11.74 to 22.51 g/day. When expressed in g/kg 0.75/day, methane emissions were higher for sheep fed fresh elephant grass with 56 days of regrowth (1.53 g/kg 0.75/day). Methane emissions expressed in g/kg of dry matter (DM) intake or neutral detergent fiber (NDF) intake were higher (P<0.05) for the grass harvested with 56 days of regrowth compared to the grass harvested in more advanced stage of maturity (112 days). However, methane emissions in g/kg of digestible DM (27.2 g/kg) and digestible NDF (44.4 g/kg) were similar among treatments. While daily methane emissions (g/kg 0.75/day) were higher in sheep fed fresh elephant grass harvested with 56 days of regrowth, it was not affected by regrowth age when expressed as g/kg of digestible DM or digestible NDF.


Subject(s)
Ruminants , Calorimetry , Sheep , Pennisetum , Greenhouse Gases , Methane
14.
Dental press j. orthod. (Impr.) ; 20(2): 42-48, Mar-Apr/2015. tab, graf
Article in English | LILACS | ID: lil-745852

ABSTRACT

OBJECTIVE: To compare the visual analogue scale (VAS) and the simplified Q-sort method used to investigate the highest level of agreement among dentists, orthodontists and laypeople when assessing smile and dental attractiveness. MATERIAL AND METHODS: An album containing 258 photos of 86 individuals with their lips at rest, a slight and broad smile, was assessed by 25 dentists (general clinicians and various specialties), 23 orthodontists and 27 laypeople with regard to smile and dental attractiveness. To this end, both VAS and simplified Q-sort method were used. Agreements were calculated by intraclass correlation coefficient (ICC). RESULTS: For the single measurement between the VAS method and the simplified Q-sort method, all simplified Q-sort rates were higher in all groups. The simplified Q-sort method results ranged between 0.42 and 0.49 while those of the VAS method varied between 0.37 and 0.42. The simplified Q-sort method also presented higher mean measurement values (0.95 and 0.96) in comparison to VAS (0.94 and 0.95). CONCLUSIONS: Both scales may be considered reliable for evaluating smile and dental attractiveness; however, the simplified Q-Sort method presented slightly higher values than the VAS method. .


OBJETIVO: comparar a escala visual analógica (EVA) e o método Q-sort simplificado quanto à maior concordância nas avaliações entre cirurgiões-dentistas, ortodontistas e leigos em atratividade dentária e do sorriso. MÉTODOS: 258 fotografias, provenientes de 86 indivíduos, fotografados com os lábios em repouso, sorriso leve e sorriso amplo, foram avaliadas quanto à atratividade dentária e do sorriso por meio da EVA e do Q-sort simplificado por 25 cirurgiões-dentistas (clínicos gerais e especialidades diversas), 23 Ortodontistas e 27 leigos. As concordâncias foram calculadas pelo Coeficiente de Correlação Intraclasse (ICC). RESULTADOS: para medida única entre a EVA e o método Q-sort simplificado, todas as taxas do Q-sort simplificado foram maiores em todos os grupos. O resultado do Q-sort simplificado variou entre 0,42 e 0,49, e da EVA entre 0,37 e 0,42. O Q-sort simplificado também apresentou valores de medida média superiores (0,95 e 0,96) em relação à EVA (0,94 e 0,95). CONCLUSÃO: pode-se considerar que ambas as escalas são confiáveis para avaliação da atratividade dentária e do sorriso; porém, o método Q-sort simplificado apresentou valores ligeiramente maiores que os da EVA. .


Subject(s)
Humans , Immunoglobulin E/physiology , B-Lymphocytes/immunology , Calorimetry , Crystallography, X-Ray , Fluorescence Resonance Energy Transfer , Hypersensitivity/immunology , Immunoglobulin E/chemistry , Protein Structure, Tertiary , Receptors, IgE/chemistry , Surface Plasmon Resonance
15.
Chinese Journal of Biotechnology ; (12): 1141-1150, 2015.
Article in Chinese | WPRIM | ID: wpr-240569

ABSTRACT

Gene expression exhibits temporal and spatial patterns to response environmental changes and growth cycle. Gene expression is under strict control at different levels among which control at transcription level is the predominant mode, especially in prokaryotes. In this review, we summarized the new developments of methods used in transcriptional studies, including modifications and improvements of the classic methods, such as gel-shift assay, DNA foot printing, and in vivo reporter system. In addition, we introduced examples to apply new methods, such as surface plasmon resonance (SPR) and isothermal titration calorimetry (ITC) to characterize protein-DNA, ligand-protein, and ligand-protein-DNA interactions. The collection of these methods and their application could guide and accelerate relevant studies.


Subject(s)
Calorimetry , DNA Footprinting , Gene Expression , Ligands , Proteins , Surface Plasmon Resonance , Transcription, Genetic
16.
China Journal of Chinese Materia Medica ; (24): 889-893, 2015.
Article in Chinese | WPRIM | ID: wpr-330215

ABSTRACT

To reveal the characterization of interaction between Chinese and western medicinal injections, isothermal titration calorimetry (ITC) was applied to evaluating the interaction of Yiqi Fumai injection (YQFM, as mode drug) with epinephrine hydrochloride injection (YS) and 5% glucose injection (5% GS). The diversification of Gibbs free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) were determined to judge the reaction types of colliquefaction procedures of different injections. Meanwhile, the fingerprints of YQFM before and after combined with the various injections were compared to validate the results. This work demonstrated that during the titration procedure of YQFM and YS, [ΔH] > T [ΔS] , that was to say the reaction was enthalpy-driving. And the reactive profile indicated that a great deal of heat gave out during the procedure. Obviously, chemical reactions happened and the internal component changed. On the other side, the reaction of YQFM combined with 5% GS was entropy-driving, because [ΔH] < T [ΔS]. The reactive profile showed there was only a little heat released. So non-chemical reactions happened and the major ingredients did not change. ITC could be applied to the evaluation on compatibility of other kinds of Chinese and western medicinal injection combination.


Subject(s)
Calorimetry , Drug Interactions , Drugs, Chinese Herbal , Chemistry , Pharmacology , Entropy , Epinephrine , Chemistry , Pharmacology , Glucose , Chemistry , Pharmacology , Injections , Thermodynamics
17.
The Korean Journal of Sports Medicine ; : 29-33, 2015.
Article in Korean | WPRIM | ID: wpr-181095

ABSTRACT

Calculating the estimated resting metabolic rate (RMR) in severely obese patients is useful, but there is controversy concerning the effectiveness of available predictive equations using body weight. This study compared the accuracy of four commonly used RMR predictive equations to measured RMR. We evaluated the efficacy of RMR equations against indirect calorimetry in forth female obese subjects. The subjects had their RMR measured by indirect calorimetry and compared to the most commonly used prediction equations (Harris-Benedict, Owen, and Mifflin-St Jeor, World Health Organization/Food and Agriculture Organization/United Nations University [WHO/FAU/UNU]). The results shows that Owen and Mifflin-St Jeor equations significantly under-estimated to our measured RMR. However, the WHO/FAO/UNU Equation was the most accurately predictive RMR values (1,543.6+/-110.3 vs. 1,484.3+/-218.3) compared to measured RMR. As based on data, we suggest that WHO/FAO/UNU equation and Harris-Benedicts equation would be most reasonable and useful for Korean obese women.


Subject(s)
Female , Humans , Agriculture , Body Weight , Calorimetry , Calorimetry, Indirect , Obesity , Predictive Value of Tests , Global Health , World Health Organization
18.
Neotrop. ichthyol ; 12(4): 783-794, Oct-Dec/2014. tab, graf
Article in English | LILACS | ID: lil-732614

ABSTRACT

The variation in energy in the muscles of the most representative fish species from three Neotropical Reservoirs was investigated to determine the effect of the reproductive process on the amount of energy allocated and a possible relationship between the general welfare of the species and their caloric content. Significant differences were detected between the sexes and among the stages of gonad maturity. In general, the variation in energy in the muscles indicate to be a function of the reproductive cycle. In most examined species, females presented the highest caloric values, reflecting physiological differences in their use of energy, relative to the reproductive process. However, there was no significant correlation between caloric values and the condition factor of any species. Significant differences in the caloric content and condition factor were identified in each species belonging different trophic groups, indicating an effect of food quality on the amount of energy stored in the muscles. We conclude that the analyzed species presented a similar pattern of variation in energy, but that this was not reflected in their condition. In addition, an effect of reproduction and feeding habit on energy allocation was observed in both sexes.


Foi investigada a variação da energia nos músculos das espécies de peixes mais representativas de três reservatórios neotropicais, para determinar o efeito do processo reprodutivo na quantidade de energia alocada e uma possível relação entre o bem-estar geral das espécies e seu conteúdo calórico. Foram detectadas diferenças significativas entre os sexos e os estádios de maturidade gonadal. Em geral, a variação da energia nos músculos demonstra ser dependente do ciclo reprodutivo. Na maioria das espécies estudadas, as fêmeas apresentaram os maiores valores calóricos, refletindo as diferenças fisiológicas no uso de sua energia, em relação ao processo reprodutivo. No entanto, não houve correlação significativa entre os valores calóricos e o fator de condição as espécies estudadas. Diferenças significativas do conteúdo calórico e no fator de condição foram identificadas em cada espécie pertencente aos diferentes grupos trófcos, indicando um efeito de qualidade alimentar sobre a quantidade de energia armazenada nos músculos. Conclui-se que as espécies analisadas apresentaram um padrão semelhante de variação de energia, mas que isso não se refletiu em sua condição. Além disso, um efeito da reprodução e hábito alimentar, sobre a alocação de energia, foi observado em ambos os sexos.


Subject(s)
Animals , Energy Intake/physiology , Muscles/physiology , Fishes/physiology , Calorimetry/veterinary
19.
Arq. bras. med. vet. zootec ; 65(6): 1752-1758, Dec. 2013. graf, tab
Article in English | LILACS | ID: lil-696858

ABSTRACT

The accuracy of two different methods in measuring the ammonia nitrogen (N-NH3) concentration in rumen fluid were evaluated: a catalyzed indophenol colorimetric reaction (CICR) and the Kjeldahl distillation (KD). Five buffered standard solutions containing volatile fatty acids, true protein, and known ammonia concentrations (0, 3, 6, 12, and 24 N-NH3 mg/dL) were used to simulate rumen fluid. Different ratios (10:1, 7.5:1, 5:1, 2.5:1, 1:1, 1:2.5, 1:5, 1:7.5, and 1:10) of a potassium hydroxide solution (KOH, 2 mol/L) to standard solutions were evaluated by the KD method. The accuracy of each method was evaluated by adjusting a simple linear regression model of the estimated N-NH3 concentrations on the N-NH3 concentrations in the standard solutions. When the KD method was used, N-NH3 was observed to be released from the deamination of true protein (P<0.05), and an incomplete recovery of N-NH3 was observed (P<0.05), except for 7.5:1 and 5:1 ratios of KOH solution to standard solutions (P>0.05). The estimates of the N-NH3 concentration obtained by the CICR method were found to be accurate (P>0.05). After the accuracy evaluation, ninety-three samples of rumen fluid were evaluated by the CICR and KD methods (using the 5:1 ratio of KOH solution to rumen fluid sample), assuming that the CICR estimates would be accurate. The N-NH3 concentrations obtained by the two methods were observed to be different (P<0.05) but strongly correlated (r = 0.9701). Thus, it was concluded that the estimates obtained by the Kjeldahl distillation using a 5:1 ratio of KOH solution to rumen fluid sample can be adjusted to avoid biases. Furthermore, a model to adjust the N-NH3 concentration is suggested.


Avaliou-se a exatidão de dois métodos para mensuração da concentração de nitrogênio amoniacal (N-NH3) em fluido ruminal: reação colorimétrica catalisada por indofenol (RCCI) e destilação de Kjeldahl (DK). Cinco soluções-tampão contendo ácidos graxos voláteis, proteína verdadeira e concentrações conhecidas de amônia (0, 3, 6, 12 e 24 N-NH3mg/dL) foram utilizadas para simular o fluido ruminal. Diferentes relações (10:1; 7,5:1; 5:1; 2,5:1; 1:1; 1:2,5; 1:5; 1:7,5 e 1:10) entre a solução de hidróxido de potássio (KOH, 2 mol/L) e as soluções-padrão foram avaliadas no método DK. A exatidão de cada método foi avaliada por intermédio do ajustamento de um modelo de regressão linear simples das concentrações estimadas de N-NH3sobre as concentrações reais de N-NH3nas soluções-padrão. Com a utilização da DK observou-se que N-NH3foi liberada a partir da deaminação de proteína verdadeira (P<0,05). Adicionalmente, a utilização da DK promoveu recuperação incompleta da N-NH3(P<0,05), com exceção das razões entre a solução de KOH e as soluções-padrão de de 7,5:1 e de 5:1 (P>0,05). As estimativas de concentração de amônia obtidas por intermédio do método de RCCI foram exatas (P>0,05). Após a avaliação da exatidão, noventa e três amostras de fluido ruminal foram avaliadas por intermédio dos métodos de RCCI e de DK (neste caso usando a razão entre solução de KOH e fluido ruminal de 5:1). Nesta avaliação assumiu-se que as estimativas obtidas com a RCCI seriam exatas. Observou-se que as concentrações de N-NH3obtidas pelos dois métodos foram diferentes (P<0,05), mas fortemente correlacionadas (r = 0,9701). Concluiu-se que as estimativas obtidas com a DK utilizando-se razão entre a solução de KOH e a amostra de fluido ruminal de 5:1 poderiam ser ajustadas para correções de vieses Um modelo para realização desse ajustamento foi sugerido.


Subject(s)
Animals , Cattle , Ammonia/analysis , Calorimetry/methods , Distillation/methods , Ruminants
20.
Acta Pharmaceutica Sinica ; (12): 1590-1594, 2013.
Article in Chinese | WPRIM | ID: wpr-298039

ABSTRACT

The study is aimed to investigate the effect of lamivudine on growth and metabolism of three intestinal characteristic bacteria (namely, Bifidobacterium adolescentis, Escherichia coli and Shigella dysenteriae). The growth condition of the three bacteria was quantitatively evaluated by microcalorimetry with four characteristic parameters of the thermal power-time curves, including the growth rate constant (k), thermal power (p), time to peak (t) and calorific value (Q). The results showed that the IC50 value of lamivudine on B. adolescentis was 200 microg x mL(-1), and the IC50 values of lamivudine on S. dysenteriae and E. coli were higher than 3 000 microg x mL(-1) and 6 000 microg x mL(1), respectively. Therefore, lamivudine made different inhibitory effects on the three bacteria, in which the B. adolescentis was most susceptible to lamivudine. This work showed that taking lamivudine chronically is likely to affect the balance of good flora in the intestinal tract, and might increase endotoxin release, leading to inflammation and disease progression in hepatopathy.


Subject(s)
Anti-Bacterial Agents , Pharmacology , Bifidobacterium , Calorimetry , Escherichia coli , Lamivudine , Pharmacology , Shigella dysenteriae
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